CA2059055C - High voltage converter - Google Patents
High voltage converterInfo
- Publication number
- CA2059055C CA2059055C CA002059055A CA2059055A CA2059055C CA 2059055 C CA2059055 C CA 2059055C CA 002059055 A CA002059055 A CA 002059055A CA 2059055 A CA2059055 A CA 2059055A CA 2059055 C CA2059055 C CA 2059055C
- Authority
- CA
- Canada
- Prior art keywords
- high voltage
- circuit means
- power
- voltage converter
- switch
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M19/00—Current supply arrangements for telephone systems
- H04M19/02—Current supply arrangements for telephone systems providing ringing current or supervisory tones, e.g. dialling tone or busy tone
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
Abstract
High voltage converters are disclosed. The converters include at least a pair of transistor switches provided on the secondary windings of a flyback transformer.
The transistor switches are controlled to be conducting, variably conducting and non-conducting so that the power flow between the transformer and a load can be controlled.
Various configurations of a connection switch network are also disclosed.
The transistor switches are controlled to be conducting, variably conducting and non-conducting so that the power flow between the transformer and a load can be controlled.
Various configurations of a connection switch network are also disclosed.
Description
HIG~ VOLTAGE ~NV ~k . ~:K
FIELD OF THE IN V~N~ oN
-The present invention relates to a high voltage converter for providing a load with an AC power of the desired waveform in which charging and discharging of the power to and from the load is controlled. More specifi-cally, the invention is directed to the high voltage converter used in a system where controlled DC power, AC
power and a combination of both are required for its operation. As one of the preferred embodiments, the system to which the present invention can be applied is the telephone system where controlled DC and/or AC voltage higher than a DC source voltage provided in the system is required for certain telephony functions.
BACKGROUND OF THE lN V~N~l~loN
In the field of telephony, it has historically been considered to be too costly to provide high voltage signalling, such as ringing and coin telephone control, on a per-line basis. Instead, these functions have usually been provided by common generators. Each generator serves a number of lines, being switched onto each line when required, by a relay on the line circuit. However, this approach does have drawbacks, as will be described below, and does not easily extend to other forms of high voltage signalling, such as message waiting. As further requirements, to reduce impulse noise while ringing, the relay movement should be timed to coincide with a "zero crossing" of the ringing AC waveform. Also, party lines may require "selective ringing", involving: (a) providing the ringing voltage to one or other side of the line, relative to ground; (b) superimposing either a negative or a positive DC voltage onto the AC ringing voltage; (c) ringing at different frequencies. Due to the burden of providing the correct type of signal to each line as required, without overloading the generators when traffic is high, there can be significant time delay in providing signalling operations, so it is not possible to guarantee a desirable "immediate ring" feature. For message waiting signalling it is essential that the voltage be applied and removed slowly, in order to avoid solln~ing the subscriber's ringers. Also, the maximum current delivered to each line should be limited for safety reasons not to exceed a few milliamperes. These special requirements are additional to those providing ringing or coin operation, further increasing the cost.
Electronic techniques for supplying DC and AC
power to a telephone line or other load line are well known.
One reason for using electronic means for supplying DC power is to reduce heat dissipation within the line circuit. Heat dissipation can be further reduced by adjusting the voltage of the DC supply in accordance with the line resistance.
Since line resistances differ, preferably this is done by providing efficient power conversion for each line individually.
U.S. Patent No. 4,761,812, issued Aug. 1988 (Hollis el al), teaches a constant power telephone line circuit. It comprises a flyback switching power converter having a switching transistor circuit, a transformer having a primary winding coupled to the switching transistor circuit and device for discharging energy stored in the core such that the power output is a constant power pulse. U.S.
Patent No. 4,674,119, issued June 16, 1987 (Chea, Jr.), describes a wide band high voltage amplifier for telephony.
It also uses a flyback generator with a capacitor storage element coupled across the line and an error signal controls the energy transfer from the flyback converter to the line.
U.S. Patent No. 4,056, 689, issued Nov. 1, 1977 (Freimanis), on the other hand, describes a communication line interface circuit including a floating current source supplying a constant current substantially independent of loop length.
The line interface circuit is provided with circuitry for line supervision and the detection of dial pulse signalling.
A need therefore exists for an efficient power converter not only for the telephone system but also for systems where precise control of power flow into and out of a load is required. For example, such converters are useful in the field of motor control of computer tape drives, and of read/write heads in computer disk drives, which are required to have rapid starting, stopping, and reversing characteristics.
In telephony, the converter should be able to supply DC power of an adjustable voltage for providing balanced line feed for the idle, addressing and transmission states of the line. It should also be able to supply AC
power of a desired waveform at voltages higher than the DC
source voltage. A voltage higher than a DC source is used if, for example, it should happen that the DC source voltage typically from a battery is unusually low. A voltage lower than the DC source might be used when the line resistance is less than the normal maximum. The converter can alterna-tively supply signalling power to one or the other side, or both sides, of the line, when the situation requires voltages higher than or of the opposite polarity from that of the DC source. These situations include ringing, coin telephone signalling and control, and message-waiting signalling.
OBJECTS OF THE lNv~NllON
It is therefore an object of the present invention to provide a high voltage converter which is able to control the flow of the power to and from the load.
It is another object of the present invention to provide a high voltage converter which is able to connect selectively on demand a line driver circuit or a high voltage circuit to the load.
It is still a further object of the present invention to provide a high voltage converter which includes a connection switch network in a more efficient switch configuration.
SUMMARY OF THE lNv~NllON
Briefly stated, the present invention relates to a high voltage converter for providing a power to a load by load connection lines from a DC voltage source. The converter comprises a line driver circuit means to be connected to the DC voltage source for providing a line drive output and high voltage circuit means to be connected to the DC voltage source for providing a high voltage output. It further includes connection switch means for selectively connecting the line driver circuit means and the ~ high voltage circuit means to the load con~Pction lines for providing the line drive output, the high voltage output or a combination thereof. The high voltage circuit means in turn comprises a flyback transformer which has a primary winding and two secon~Ary windings. The high voltage circuit means further includes a primary transistor switch connected to the primary winding for supplying the pulsed power thereto from the DC voltage source in a controlled pulsing manner and a secon~Ary transistor switch and diode combination connected to each of the two secondary windings for controlling the flow of the power generated therein as the result of the power supplied to the primary winding.
Each of the secondary transistor switches is turned on or off in-a controlled manner so that a high voltage output of a specific waveform is produced.
BRIEF DESCRIPTION OF THE DRAWINGS
For a more complete underst~n~ing of the present invention and for further objects and advantages thereof, reference may now be made to the following description, _ 5 taken in conjunction with the accompanying drawings, in which:
Figure 1 is a schematic block diagram of the high voltage converter according to one embodiment of the invention;
Figure 2 shows diagrams of voltage-current characteristics of some typical loads;
Figure 3 is a schematic circuit diagram of the high voltage circuit means according to one embodiment of the invention;
Figure 4 is a block diagram of the power control circuit according to one embodiment of the invention;
Figure 5 is a schematic circuit diagram of the high voltage circuit means according to another embodiment of the invention;
Figure 6 is a circuit diagram of the overcurrent detector circuit;
Figure 7 is a circuit diagram of the power switching control circuit according to one embodiment of the invention;
Figure 8 shows power switching control circuit ouL~uL signals; and Figures 9a and 9b are schematic block diagrams showing switch configurations according to two embodiments of the invention.
DETATT~D DESCRIPTION OF THE ~KKED EMBODIMENTS
Figure 1 shows in a schematic block diagram the high voltage converter system according to one embodiment of the present invention. In the figure a load 10 is supplied with a controlled power by load connection lines which may be four lines in simplex configuration in other embodiments.
A line driver circuit means 12 provides various controlled DC power or AC of a desired waveform, or a combination of both to its output terminals which are connected to a current and voltage sensing network 14 via co~ection switch network 16 consisting of a plurality of switches Sl, S2, S3.... . A high voltage circuit means 18 produces a high voltage output either in AC or DC or both which is sent to the connection switch network 16. By specifically configuring the connection switch network, the high voltage output can be supplied to the load through any of the load connection lines either directly or by way of the line driver circuit means 12. A power control circuit means 20 is under control of a program load and command 22 and is responsive to the sensing output of the current and voltage sensing network 14 to generate control signals for the high voltage circuit means 18 and the connection switch network 16. A battery or other DC power source 24 provides not only the operating power for various circuits and networks but also the power which is supplied to the load directly or the power which is to be converted by the high voltage circuit means before being supplied to the load. The connection switch network 16 can be constructed from mechAn;cal switches, solid-state switches or a combination of these.
The power control circuit means may include a combination of digital and analog hardware, operated by a digital controller which may be implemented using computer architecture with stored program software.
In various areas, a high voltage converter may involve driving reactive loads in both negative and positive polarities, such that power must at some times be delivered to the load, but at other times must be discharged from the load. To cover all situations requires that the converter is able to operate in four distinct modes, or "guadrants", and is able to switch moderately quickly from any mode to any other mode. The four operating quadrants will here be called active source, passive source, active sink, and passive sink. They are shown on a voltage-current diagram in Figure 2. In the figure, a graph 30 indicates the voltage-current characteristics of a standard load impedance in the telephone system as an example and chosen to be equivalent to 5 ringers in parallel, being driven by a voltage that is controlled to vary sinusoidally with time, superimposed on a DC voltage component.
A telephone ringer draws an AC component of current but not a DC component. The evident elliptical shape of the voltage-current curve indicates that the load impP~AnçD in this example includes a reactive component.
Owing to the existence of a DC component of voltage but not of current, the operating characteristic in this example enters three but not all of the quadrants. However, in cases where the load has a higher reactance or there is no DC superimposition, the operation of the high voltage converter could enter into all four quadrants in turn, as shown by a graph 32.
Figure 3 illustrates schematically the high voltage circuit means according to one embodiment of the invention. For operation in the active source and active sink quadrants, transistor Ql is switched on and off at a periodic high frequency by a pulsing control signal PCD.
While Ql is conducting, energy is transferred from the battery or other DC source to transformer T1. When Ql turns off, Tl supplies energy to a reservoir capacitor Cl by the known principles of a flyback power converter. Tl is provided with two secondary w;n~;~gs, and correspondingly two rectifying diodes Dl, D2. The high voltage circuit means is provided with two "grounding switches" consisting of transistors Q2 and Q3 with associated driver circuits.
By selecting which of Q2 or Q3 is to be conducting by means of control signals PG and NG, the voltage provided to the load 30 may be chosen to be of either polarity. To minimize power losses, the transistor selected to conduct is made to be as fully conducting as is reasonably possible. The ouL~uL power is controlled by varying the "ON" duty cycle of Ql. Control signals applied to the Q2 and Q3 driver circuits turn Q2 and Q3 on and off in desired manner so that reguired turns-on/off durations, timings, waveforms of the ouL~uL, etc. can be controlled.
It should therefore be noted that unlike known DC
converters, the high ~oltage circuit means of Figure 3 utilizes the same transistors Q2 and Q3 for discharging power from the load in the operation of passive source or passive sink quadrants. In these operations, since no power is required to be taken from the battery, Ql is held non-conducting. By making selected Q2 or Q3 conduct in a controlled manner, power can be discharged at the rate needed at any time to maintain the desired instantaneous voltage across the load of various impedance values.
In the field of telephony, the line driver circuit means 12 provides a variety of controlled DC power or normal voice or information carrying tone AC signal power at its output terminals. Ordinarily, the line driver circuit means contains multiple of ICs, e.g. op amps etc., and therefore the terminals VEE and VCC are provided for their operation. The terminal VCC is supplied with the regular operating power from the DC power supply 24.
Various switch configurations of the connection switch means 16 can be chosen so that the terminal VEE is suppl~ ed with power either from the DC power source or the high voltage circuit means as a need for increased voltage or desired waveforms could arise.
The connections provided via the connection switch means determine the operating modes that can be provided. Table 1 below shows how the switches Sl through S8 shown in Figure 1 allow various telephony operating modes to be provided. In the table, LDC and HVC stand for the line driver circuit and the high voltage circuit, e.g.
the means shown in Figur~ 1 by 12 and 18, respectively. Of course, there are many other possible combinations of these switches which are appropriate for other applications.
205~055 g # S l S2 S3 S4 SS S6 S7 S8 HVC TFT FPHONY APPLICATION
STATUS
C X C C - - inactive Loop ~dle or DC feed (LDC on Tip,Rin~) 2 - C C C - - active Loop Idle or DC feed (LDC on Tip,Rin~) 3 C C X - - - inactive Ground Start (Tip open. LDC on Rin~) 4 C - - C C -active Sign~ ng on Tip (HVC on Tip, LDC on Rin~) S X - C -active Coin sig~iling on Tip (HVC on Tip, Rin~ oPen) 6 C - C - C - -active Signalling on Ring (HVC on Rin~, LDC on Tip) 7 X - C C - -active Simplex Coin sign~lling (HVC on both Tip & Rins~
8 X - - - C Cactive Sign~lling on Ti~
(HVC on Tip, Gn~ on Rin~) 9 X - C C -active Signalling on R ng (HVC on Rin~, Gnd on Tip) Definition of symbols:
- ~ open 20 C - closed X = status uni~ G- lant (a "don't care" state).
When Sl is closed, the battery negative lead is connected to the negative supply point VEE of the line driver circuit means. In this situation, either S2 should be open, or if it is closed, the high voltage circuit means must be inactive. Sl may be opened, and S2 closed, to supply power to the loop via the high voltage circuit means.
The usual reason for doing this is to provide a voltage different from that of the battery. The high voltage circuit means may be designed so that when inactive, it presents a high imp~AncD at its output terminals. This 3 5 will be assumed to be the case.
Figure 4 is a block circuit diagram of the power control circuit means 20 which includes a reference control circuit 40, a summing circuit 42, low-pass filter 43, and a power swit~h; ng control circuit 44. Like numerals are used in the figure to indicate like elements shown in Figure 1.
The reference control circuit 40 generates a smooth analog reference voltage Vref that is a replica (on a reduced scale) of the loop powering voltage or signalling voltage that is to be generated. The summing circuit 42 generates a voltage difference between Vref and a fraction k of the output voltage Vout of the high voltage circuit means, which is filtered by the low-pass filter to create an error voltage Verr. The low-pass filter is provided to remove high-frequency noise. The reference control circuit 40 can be made of hard-wired circuit or computer-type architecture, operated by stored program coding.
In addition to the Vout signal, the current and voltage sensing network 14 produces signals indicative of other conditions of the power supplied to the load, e.g.
differential current etc. In telephony, the common mode current can be sensed here also. The high voltage circuit means can be provided with an overcurrent detector which generates an overcurrent trip signal 50 whose message 52 can be sent to the reference control circuits 40.
The power switch;~g control circuit 44 determines in which quadrant of operation the power converter is required to be at any time, and applies control voltages to the transistor switches Ql, Q2, Q3 of the high voltage circuit means in such a way as to reduce the error voltage.
Table 2 below illustrates, in terms of six different operating situations, how the four quadrants can be identified by the sign of Vref and by the sign and magnitude of Verr. They define whether Ql should be pulsed, and which of Q2 or Q3 should be turned on, and whether the status of Ql or Q3 should be highly conductive, or conducting in a controlled manner in proportion to the magnitude of the error. The pulse duration applied to Ql must never exceed a defined maximum value, in order to allow sufficient time for flyback, when the energy transferred into transformer Tl during the "on" period of Ql is transferred to the load. For small errors, optional but preferred "hold zones" are defined in Table 2. The purpose of the hold zones is to avoid problems caused by finite turn-off times and finite turn-on times in switches Q2 and Q3. Otherwise, when a transition into an active quadrant occurs, there is a risk that the high-speed switching of Ql starts while, for a short time (1) both Q2 and Q3 are conducting simultaneously, and (2) neither Q2 nor Q3 is conducting. Problem (1) would cause a short circuit and problem (2) an open circuit, in either case with risk of hardware damage.
Power Converter Situations (Inset~ Functions of Power Switching Control Circuit No Sign ot Sign (M~yll ) auadrant NG (a2) PCD (a1) PG (a3) R~ ~nc6~ of Error #
Negathe Negative Passive Varlable 202 Negative Positive (small) Hold ........................................... Highly C~
Active Conducting 3 Negative Positive Sink Var. pulse 4 Positive Negative Active Var. pulse Highly ............................................... C~' J
FIELD OF THE IN V~N~ oN
-The present invention relates to a high voltage converter for providing a load with an AC power of the desired waveform in which charging and discharging of the power to and from the load is controlled. More specifi-cally, the invention is directed to the high voltage converter used in a system where controlled DC power, AC
power and a combination of both are required for its operation. As one of the preferred embodiments, the system to which the present invention can be applied is the telephone system where controlled DC and/or AC voltage higher than a DC source voltage provided in the system is required for certain telephony functions.
BACKGROUND OF THE lN V~N~l~loN
In the field of telephony, it has historically been considered to be too costly to provide high voltage signalling, such as ringing and coin telephone control, on a per-line basis. Instead, these functions have usually been provided by common generators. Each generator serves a number of lines, being switched onto each line when required, by a relay on the line circuit. However, this approach does have drawbacks, as will be described below, and does not easily extend to other forms of high voltage signalling, such as message waiting. As further requirements, to reduce impulse noise while ringing, the relay movement should be timed to coincide with a "zero crossing" of the ringing AC waveform. Also, party lines may require "selective ringing", involving: (a) providing the ringing voltage to one or other side of the line, relative to ground; (b) superimposing either a negative or a positive DC voltage onto the AC ringing voltage; (c) ringing at different frequencies. Due to the burden of providing the correct type of signal to each line as required, without overloading the generators when traffic is high, there can be significant time delay in providing signalling operations, so it is not possible to guarantee a desirable "immediate ring" feature. For message waiting signalling it is essential that the voltage be applied and removed slowly, in order to avoid solln~ing the subscriber's ringers. Also, the maximum current delivered to each line should be limited for safety reasons not to exceed a few milliamperes. These special requirements are additional to those providing ringing or coin operation, further increasing the cost.
Electronic techniques for supplying DC and AC
power to a telephone line or other load line are well known.
One reason for using electronic means for supplying DC power is to reduce heat dissipation within the line circuit. Heat dissipation can be further reduced by adjusting the voltage of the DC supply in accordance with the line resistance.
Since line resistances differ, preferably this is done by providing efficient power conversion for each line individually.
U.S. Patent No. 4,761,812, issued Aug. 1988 (Hollis el al), teaches a constant power telephone line circuit. It comprises a flyback switching power converter having a switching transistor circuit, a transformer having a primary winding coupled to the switching transistor circuit and device for discharging energy stored in the core such that the power output is a constant power pulse. U.S.
Patent No. 4,674,119, issued June 16, 1987 (Chea, Jr.), describes a wide band high voltage amplifier for telephony.
It also uses a flyback generator with a capacitor storage element coupled across the line and an error signal controls the energy transfer from the flyback converter to the line.
U.S. Patent No. 4,056, 689, issued Nov. 1, 1977 (Freimanis), on the other hand, describes a communication line interface circuit including a floating current source supplying a constant current substantially independent of loop length.
The line interface circuit is provided with circuitry for line supervision and the detection of dial pulse signalling.
A need therefore exists for an efficient power converter not only for the telephone system but also for systems where precise control of power flow into and out of a load is required. For example, such converters are useful in the field of motor control of computer tape drives, and of read/write heads in computer disk drives, which are required to have rapid starting, stopping, and reversing characteristics.
In telephony, the converter should be able to supply DC power of an adjustable voltage for providing balanced line feed for the idle, addressing and transmission states of the line. It should also be able to supply AC
power of a desired waveform at voltages higher than the DC
source voltage. A voltage higher than a DC source is used if, for example, it should happen that the DC source voltage typically from a battery is unusually low. A voltage lower than the DC source might be used when the line resistance is less than the normal maximum. The converter can alterna-tively supply signalling power to one or the other side, or both sides, of the line, when the situation requires voltages higher than or of the opposite polarity from that of the DC source. These situations include ringing, coin telephone signalling and control, and message-waiting signalling.
OBJECTS OF THE lNv~NllON
It is therefore an object of the present invention to provide a high voltage converter which is able to control the flow of the power to and from the load.
It is another object of the present invention to provide a high voltage converter which is able to connect selectively on demand a line driver circuit or a high voltage circuit to the load.
It is still a further object of the present invention to provide a high voltage converter which includes a connection switch network in a more efficient switch configuration.
SUMMARY OF THE lNv~NllON
Briefly stated, the present invention relates to a high voltage converter for providing a power to a load by load connection lines from a DC voltage source. The converter comprises a line driver circuit means to be connected to the DC voltage source for providing a line drive output and high voltage circuit means to be connected to the DC voltage source for providing a high voltage output. It further includes connection switch means for selectively connecting the line driver circuit means and the ~ high voltage circuit means to the load con~Pction lines for providing the line drive output, the high voltage output or a combination thereof. The high voltage circuit means in turn comprises a flyback transformer which has a primary winding and two secon~Ary windings. The high voltage circuit means further includes a primary transistor switch connected to the primary winding for supplying the pulsed power thereto from the DC voltage source in a controlled pulsing manner and a secon~Ary transistor switch and diode combination connected to each of the two secondary windings for controlling the flow of the power generated therein as the result of the power supplied to the primary winding.
Each of the secondary transistor switches is turned on or off in-a controlled manner so that a high voltage output of a specific waveform is produced.
BRIEF DESCRIPTION OF THE DRAWINGS
For a more complete underst~n~ing of the present invention and for further objects and advantages thereof, reference may now be made to the following description, _ 5 taken in conjunction with the accompanying drawings, in which:
Figure 1 is a schematic block diagram of the high voltage converter according to one embodiment of the invention;
Figure 2 shows diagrams of voltage-current characteristics of some typical loads;
Figure 3 is a schematic circuit diagram of the high voltage circuit means according to one embodiment of the invention;
Figure 4 is a block diagram of the power control circuit according to one embodiment of the invention;
Figure 5 is a schematic circuit diagram of the high voltage circuit means according to another embodiment of the invention;
Figure 6 is a circuit diagram of the overcurrent detector circuit;
Figure 7 is a circuit diagram of the power switching control circuit according to one embodiment of the invention;
Figure 8 shows power switching control circuit ouL~uL signals; and Figures 9a and 9b are schematic block diagrams showing switch configurations according to two embodiments of the invention.
DETATT~D DESCRIPTION OF THE ~KKED EMBODIMENTS
Figure 1 shows in a schematic block diagram the high voltage converter system according to one embodiment of the present invention. In the figure a load 10 is supplied with a controlled power by load connection lines which may be four lines in simplex configuration in other embodiments.
A line driver circuit means 12 provides various controlled DC power or AC of a desired waveform, or a combination of both to its output terminals which are connected to a current and voltage sensing network 14 via co~ection switch network 16 consisting of a plurality of switches Sl, S2, S3.... . A high voltage circuit means 18 produces a high voltage output either in AC or DC or both which is sent to the connection switch network 16. By specifically configuring the connection switch network, the high voltage output can be supplied to the load through any of the load connection lines either directly or by way of the line driver circuit means 12. A power control circuit means 20 is under control of a program load and command 22 and is responsive to the sensing output of the current and voltage sensing network 14 to generate control signals for the high voltage circuit means 18 and the connection switch network 16. A battery or other DC power source 24 provides not only the operating power for various circuits and networks but also the power which is supplied to the load directly or the power which is to be converted by the high voltage circuit means before being supplied to the load. The connection switch network 16 can be constructed from mechAn;cal switches, solid-state switches or a combination of these.
The power control circuit means may include a combination of digital and analog hardware, operated by a digital controller which may be implemented using computer architecture with stored program software.
In various areas, a high voltage converter may involve driving reactive loads in both negative and positive polarities, such that power must at some times be delivered to the load, but at other times must be discharged from the load. To cover all situations requires that the converter is able to operate in four distinct modes, or "guadrants", and is able to switch moderately quickly from any mode to any other mode. The four operating quadrants will here be called active source, passive source, active sink, and passive sink. They are shown on a voltage-current diagram in Figure 2. In the figure, a graph 30 indicates the voltage-current characteristics of a standard load impedance in the telephone system as an example and chosen to be equivalent to 5 ringers in parallel, being driven by a voltage that is controlled to vary sinusoidally with time, superimposed on a DC voltage component.
A telephone ringer draws an AC component of current but not a DC component. The evident elliptical shape of the voltage-current curve indicates that the load impP~AnçD in this example includes a reactive component.
Owing to the existence of a DC component of voltage but not of current, the operating characteristic in this example enters three but not all of the quadrants. However, in cases where the load has a higher reactance or there is no DC superimposition, the operation of the high voltage converter could enter into all four quadrants in turn, as shown by a graph 32.
Figure 3 illustrates schematically the high voltage circuit means according to one embodiment of the invention. For operation in the active source and active sink quadrants, transistor Ql is switched on and off at a periodic high frequency by a pulsing control signal PCD.
While Ql is conducting, energy is transferred from the battery or other DC source to transformer T1. When Ql turns off, Tl supplies energy to a reservoir capacitor Cl by the known principles of a flyback power converter. Tl is provided with two secondary w;n~;~gs, and correspondingly two rectifying diodes Dl, D2. The high voltage circuit means is provided with two "grounding switches" consisting of transistors Q2 and Q3 with associated driver circuits.
By selecting which of Q2 or Q3 is to be conducting by means of control signals PG and NG, the voltage provided to the load 30 may be chosen to be of either polarity. To minimize power losses, the transistor selected to conduct is made to be as fully conducting as is reasonably possible. The ouL~uL power is controlled by varying the "ON" duty cycle of Ql. Control signals applied to the Q2 and Q3 driver circuits turn Q2 and Q3 on and off in desired manner so that reguired turns-on/off durations, timings, waveforms of the ouL~uL, etc. can be controlled.
It should therefore be noted that unlike known DC
converters, the high ~oltage circuit means of Figure 3 utilizes the same transistors Q2 and Q3 for discharging power from the load in the operation of passive source or passive sink quadrants. In these operations, since no power is required to be taken from the battery, Ql is held non-conducting. By making selected Q2 or Q3 conduct in a controlled manner, power can be discharged at the rate needed at any time to maintain the desired instantaneous voltage across the load of various impedance values.
In the field of telephony, the line driver circuit means 12 provides a variety of controlled DC power or normal voice or information carrying tone AC signal power at its output terminals. Ordinarily, the line driver circuit means contains multiple of ICs, e.g. op amps etc., and therefore the terminals VEE and VCC are provided for their operation. The terminal VCC is supplied with the regular operating power from the DC power supply 24.
Various switch configurations of the connection switch means 16 can be chosen so that the terminal VEE is suppl~ ed with power either from the DC power source or the high voltage circuit means as a need for increased voltage or desired waveforms could arise.
The connections provided via the connection switch means determine the operating modes that can be provided. Table 1 below shows how the switches Sl through S8 shown in Figure 1 allow various telephony operating modes to be provided. In the table, LDC and HVC stand for the line driver circuit and the high voltage circuit, e.g.
the means shown in Figur~ 1 by 12 and 18, respectively. Of course, there are many other possible combinations of these switches which are appropriate for other applications.
205~055 g # S l S2 S3 S4 SS S6 S7 S8 HVC TFT FPHONY APPLICATION
STATUS
C X C C - - inactive Loop ~dle or DC feed (LDC on Tip,Rin~) 2 - C C C - - active Loop Idle or DC feed (LDC on Tip,Rin~) 3 C C X - - - inactive Ground Start (Tip open. LDC on Rin~) 4 C - - C C -active Sign~ ng on Tip (HVC on Tip, LDC on Rin~) S X - C -active Coin sig~iling on Tip (HVC on Tip, Rin~ oPen) 6 C - C - C - -active Signalling on Ring (HVC on Rin~, LDC on Tip) 7 X - C C - -active Simplex Coin sign~lling (HVC on both Tip & Rins~
8 X - - - C Cactive Sign~lling on Ti~
(HVC on Tip, Gn~ on Rin~) 9 X - C C -active Signalling on R ng (HVC on Rin~, Gnd on Tip) Definition of symbols:
- ~ open 20 C - closed X = status uni~ G- lant (a "don't care" state).
When Sl is closed, the battery negative lead is connected to the negative supply point VEE of the line driver circuit means. In this situation, either S2 should be open, or if it is closed, the high voltage circuit means must be inactive. Sl may be opened, and S2 closed, to supply power to the loop via the high voltage circuit means.
The usual reason for doing this is to provide a voltage different from that of the battery. The high voltage circuit means may be designed so that when inactive, it presents a high imp~AncD at its output terminals. This 3 5 will be assumed to be the case.
Figure 4 is a block circuit diagram of the power control circuit means 20 which includes a reference control circuit 40, a summing circuit 42, low-pass filter 43, and a power swit~h; ng control circuit 44. Like numerals are used in the figure to indicate like elements shown in Figure 1.
The reference control circuit 40 generates a smooth analog reference voltage Vref that is a replica (on a reduced scale) of the loop powering voltage or signalling voltage that is to be generated. The summing circuit 42 generates a voltage difference between Vref and a fraction k of the output voltage Vout of the high voltage circuit means, which is filtered by the low-pass filter to create an error voltage Verr. The low-pass filter is provided to remove high-frequency noise. The reference control circuit 40 can be made of hard-wired circuit or computer-type architecture, operated by stored program coding.
In addition to the Vout signal, the current and voltage sensing network 14 produces signals indicative of other conditions of the power supplied to the load, e.g.
differential current etc. In telephony, the common mode current can be sensed here also. The high voltage circuit means can be provided with an overcurrent detector which generates an overcurrent trip signal 50 whose message 52 can be sent to the reference control circuits 40.
The power switch;~g control circuit 44 determines in which quadrant of operation the power converter is required to be at any time, and applies control voltages to the transistor switches Ql, Q2, Q3 of the high voltage circuit means in such a way as to reduce the error voltage.
Table 2 below illustrates, in terms of six different operating situations, how the four quadrants can be identified by the sign of Vref and by the sign and magnitude of Verr. They define whether Ql should be pulsed, and which of Q2 or Q3 should be turned on, and whether the status of Ql or Q3 should be highly conductive, or conducting in a controlled manner in proportion to the magnitude of the error. The pulse duration applied to Ql must never exceed a defined maximum value, in order to allow sufficient time for flyback, when the energy transferred into transformer Tl during the "on" period of Ql is transferred to the load. For small errors, optional but preferred "hold zones" are defined in Table 2. The purpose of the hold zones is to avoid problems caused by finite turn-off times and finite turn-on times in switches Q2 and Q3. Otherwise, when a transition into an active quadrant occurs, there is a risk that the high-speed switching of Ql starts while, for a short time (1) both Q2 and Q3 are conducting simultaneously, and (2) neither Q2 nor Q3 is conducting. Problem (1) would cause a short circuit and problem (2) an open circuit, in either case with risk of hardware damage.
Power Converter Situations (Inset~ Functions of Power Switching Control Circuit No Sign ot Sign (M~yll ) auadrant NG (a2) PCD (a1) PG (a3) R~ ~nc6~ of Error #
Negathe Negative Passive Varlable 202 Negative Positive (small) Hold ........................................... Highly C~
Active Conducting 3 Negative Positive Sink Var. pulse 4 Positive Negative Active Var. pulse Highly ............................................... C~' J
5 Positive Negative (small) Hold 6 Positive Positive Passive Variable CfF C~:
In the field of telephony as one of the preferred embodiments of the invention, for supplying controlled DC
power to the telephone line, the specific function of the reference control circuit in steady conditions, such as in the "idle" state and at other times, may be to provide a constant reference voltage. This may not be the case during or following transient changes. Also, in many situations the reference control circuit must provide a time-varying reference voltage. For example, Integrated Services Digital 205~055 ~ 12 Network (ISDN) operation may require the application of time-varying (ramped) "sealing current" power to the loop.
In the case of high-voltage signalling, it is usually required that the reference control circuit provides a time-varying reference voltage.
In both DC powering and high-voltage signalling, the reference control circuit may be required to make adjustments to the reference voltage in response to changes in the line currents - either the loop (differential) current, or the longitll~;n~l (common mode) current, or to the ~u~e..~ in one or the other of the load connection lines. The purpose of such adjustments may include limiting the current in accordance with a defined st~n~rd of operation, reducing heat dissipation within the line circuit, reducing potential hazard to personnel, or reducing any risk of damage to the components of high voltage circuit means due to overcurrent caused by abnormal loop conditions, such as ground faults or lightning. In an event that the high voltage circuit means shuts down entirely due to an overcurrent, one of the functions of the reference control circuit would be to analyze the sensing data in relation to the function being performed, then either re-enable the high voltage circuit means, or leave it disabled.
Figure 5 shows another embodiment of the high voltage circuit means. Transistors Ql, Q2 and Q3 are power-switc-h ing MOS transistors. In addition to the other essential circuit elements already shown in Figure 3, elements Rl, R2, Q4, Q5 and Q6 provide level shifting between the control signal levels provided by the power switch control circuit, and levels close to battery negative voltage. Additionally, they are able to drive Ql on and off at high speeds, as required for efficient power conversion.
Owing to level inversion by Q4, the required logical control signal is not PCD as in Figure 3, but the inverse, here labelled PCDB. In this example, Q2 is driven directly by the control signals from the power switch control circuit.
Typically, the levels of these signals would be less than _ 13 1 V (off) and up to about 10 V (on), so that Q2 can be a power MOS transistor of a standard type, yet have a low resistance to current flow when fully "on".
Unlike Q2, Q3 is required to be able to control conduction at negative voltages. However, for convenience Q3 is chosen to be of similar type to Q2, (n-channel MOS), and is arranged to control negative voltages by grounding its drain contact instead of the source contact as for Q2.
This means that the control gate of Q3 must follow close to the high negative voltage that can exist on the source contact of Q3. Elements R3, R4 and Q7 provide level shifting to control the gate voltage of Q3 under all conditions, when driven by control signal PGB, the inverted form of PG. In an alternative embodiment, high voltages on the control gate of Q3 could be avoided by choosing Q3 to be a p-channel MOS, with its source grounded. If, in addition, - Q3 were chosen to be normally-on (depletion type) MOS, its gate could be driven directly by positive control signals.
Also shown in Figure 5 is resistor R5, which has low ohmic value (typically about 1 ohm) and a detector circuit 60, which monitors the voltage drop across R5 to provide fast detection of excessive current in either polarity. This could be caused by sudden changes in the line conditions, either being normal conditions (e.g.
ringing answer) or abnormal conditions (e.g. line surges).
By arranging that the power switch control circuit then turns off Ql, Q2 and Q3, the high voltage circuit means can be disabled within a very short time, preventing possible damage to the components of the high voltage circuit means.
Figure 6 is a practical implementation of the detector circuit 60. It consists of R6 and Q8, which respond to one polarity of excessive current, (causing positive voltage input to the detector) and R7 and Q9, which respond to the opposite polarity of current. The result is that an excessive current in either polarity through R5 causes a warning current in one polarity to appear at the detector output point, labelled oC.
Figure 7 shows a possible implementation of the power switching control circuit. Elements Rl to R3, Cl and Al within the shaded boundary 70 provide the functions of the summing circuit 42 and low-pass filter 43 in Figure 4, producing the error voltage Verr. Elements R4, R5 and A2 generate -Verr (inverted error). Amplifiers A3 and A4 operate as comparators, generating digital signals SR and SE, respectively, defining the sign of the reference and the sign of the error. Amplifiers A5 and A6 operate as fast comparators, respectively, comparing Verr and -Verr against a periodic voltage ramp Vrmp, and thereby producing pulse-width modulated digital signals PWA and PWB. According to the status of SR, one or other of logical AND gates Gl or G2 is enabled to pass signal PCDB. G4 also receives a logically-unconditional (clock) signal DM, which constrains the pulse width to a chosen maximum value. This ensures that Ql in the high voltage circuit means is always switched off for a sufficient time to complete the flyback portion of its switching cycle, for every required voltage and load imp~nr~ combination Also in Figure 7, gate G5, together with switch SWl, resistor network 72 and differential amplifier 74, provide the voltage levels of NG to control the required states of Q2, namely being loff'l, or "on" with a conduction proportional to Verr, or "on" in a heavily-conducting state.
Similarly, gate G6, together with switch SW2, resistor network 76 and differential amplifier 78 provide the required levels of PGB, controlling the states of Q3.
In Figure 8 it can be seen that the ramp Vrmp commences at a voltage that is offset from the comparator reference Vdcref by a small amount. When the error magnitude is smaller than this amount, no pulse is produced at PCDB. This aids in creating the "hold zones" shown in Figure 5.
Referring back to Figure 7, the reference voltage Vdeltal should be set to a level more negative than Vdcref, so that for small error magnitudes, the NG level is clamped _ 15 at VDC-. Similarly, the reference voltage Vdelta2 should be set to a level that is more positive than Vdcref, so that for small error magnitudes the PGB level is clamped at VDC+.
This clamping of NG and PGB at small error magnitude, together with the offset in the ramp voltage as mentioned above, may incidentally cause the formation of hold zones in the passive quadrants. However, the purpose of the offsets is to ensure that for sufficiently small errors, the discharge of energy from the load can be effectively prevented.
Figure 8 further illustrates the formation of PWA
and PWB from both smaller and larger examples of the error voltage, respectively labelled Verr(l) and Verr(2) and the form of the control signals NG, PCDB and PGB, for the large and small error examples Verr(l) and Verr(2).
Figures 9a and 9b illustrate possible implement-ations of the connection switches network. In both figures, Sl is a solid-state switch, providing the same functions as Sl in Figure 1. In general, solid-state switches are convenient when the closed-circuit resistance is not required to be very low. Kl and K2 are metallic relays. In Figure 9a, a symmetrical configuration of Kl and K2 provides signalling functions 1, 2, 3, 4, 5, and 7 as listed in Table 1, but excludes normal coin signalling, listed as number 6, because it is not possible to open-circuit the Ring lead while the high voltage circuit means is active. In Figure 9b, relays Kl and K2 are connected in an offset manner, that provides the functions 1, 2, 3, 4, 5, and 6, but not the alternate form of coin signalling, listed as number 7.
The optional functions of S7 and S8 in Figure 1, - listed as applications 8 and 9 in Table 1, are not provided in either of the above configurations. Table 3 shows the available operating modes and corresponding switch and relay states for both configurations.
----- Figure 9a ---- ---- Figure 9b ----# S 1 K 1 K2 HVC S 1 K 1 K2 HVC TELEPHONY APPLICATION
C - - inactive C - - inactive Loop Idle or DC feed (LDC on Tip,Rin~) 2 - - - active - - - active Loop Idle or DC feed (LDC on Tip,Rin~) 3 C E - inactive C E - inactive Ground Start (Tip open, LDC on Rin~) 4 C E - active C E - active Signqlling on Tip (HVC on Tip, LDC on Rin~) -- Not available-- C E E active Coin signqlling on Tip (HVC on Tip, Rin~ open) 6 C - E active C - E ac~ive Signqlli~g on Ring (HVC on Rin~, LDC on Tip) 7 C E E acti ve -- Not available -- Simple~c Coin sign, lling (HVC on both Tip & Rin~) Definition of symbols:
- - switch S 1 open, or relay Kn not energized C - switch Sl closed E ~ relay Kn energized
In the field of telephony as one of the preferred embodiments of the invention, for supplying controlled DC
power to the telephone line, the specific function of the reference control circuit in steady conditions, such as in the "idle" state and at other times, may be to provide a constant reference voltage. This may not be the case during or following transient changes. Also, in many situations the reference control circuit must provide a time-varying reference voltage. For example, Integrated Services Digital 205~055 ~ 12 Network (ISDN) operation may require the application of time-varying (ramped) "sealing current" power to the loop.
In the case of high-voltage signalling, it is usually required that the reference control circuit provides a time-varying reference voltage.
In both DC powering and high-voltage signalling, the reference control circuit may be required to make adjustments to the reference voltage in response to changes in the line currents - either the loop (differential) current, or the longitll~;n~l (common mode) current, or to the ~u~e..~ in one or the other of the load connection lines. The purpose of such adjustments may include limiting the current in accordance with a defined st~n~rd of operation, reducing heat dissipation within the line circuit, reducing potential hazard to personnel, or reducing any risk of damage to the components of high voltage circuit means due to overcurrent caused by abnormal loop conditions, such as ground faults or lightning. In an event that the high voltage circuit means shuts down entirely due to an overcurrent, one of the functions of the reference control circuit would be to analyze the sensing data in relation to the function being performed, then either re-enable the high voltage circuit means, or leave it disabled.
Figure 5 shows another embodiment of the high voltage circuit means. Transistors Ql, Q2 and Q3 are power-switc-h ing MOS transistors. In addition to the other essential circuit elements already shown in Figure 3, elements Rl, R2, Q4, Q5 and Q6 provide level shifting between the control signal levels provided by the power switch control circuit, and levels close to battery negative voltage. Additionally, they are able to drive Ql on and off at high speeds, as required for efficient power conversion.
Owing to level inversion by Q4, the required logical control signal is not PCD as in Figure 3, but the inverse, here labelled PCDB. In this example, Q2 is driven directly by the control signals from the power switch control circuit.
Typically, the levels of these signals would be less than _ 13 1 V (off) and up to about 10 V (on), so that Q2 can be a power MOS transistor of a standard type, yet have a low resistance to current flow when fully "on".
Unlike Q2, Q3 is required to be able to control conduction at negative voltages. However, for convenience Q3 is chosen to be of similar type to Q2, (n-channel MOS), and is arranged to control negative voltages by grounding its drain contact instead of the source contact as for Q2.
This means that the control gate of Q3 must follow close to the high negative voltage that can exist on the source contact of Q3. Elements R3, R4 and Q7 provide level shifting to control the gate voltage of Q3 under all conditions, when driven by control signal PGB, the inverted form of PG. In an alternative embodiment, high voltages on the control gate of Q3 could be avoided by choosing Q3 to be a p-channel MOS, with its source grounded. If, in addition, - Q3 were chosen to be normally-on (depletion type) MOS, its gate could be driven directly by positive control signals.
Also shown in Figure 5 is resistor R5, which has low ohmic value (typically about 1 ohm) and a detector circuit 60, which monitors the voltage drop across R5 to provide fast detection of excessive current in either polarity. This could be caused by sudden changes in the line conditions, either being normal conditions (e.g.
ringing answer) or abnormal conditions (e.g. line surges).
By arranging that the power switch control circuit then turns off Ql, Q2 and Q3, the high voltage circuit means can be disabled within a very short time, preventing possible damage to the components of the high voltage circuit means.
Figure 6 is a practical implementation of the detector circuit 60. It consists of R6 and Q8, which respond to one polarity of excessive current, (causing positive voltage input to the detector) and R7 and Q9, which respond to the opposite polarity of current. The result is that an excessive current in either polarity through R5 causes a warning current in one polarity to appear at the detector output point, labelled oC.
Figure 7 shows a possible implementation of the power switching control circuit. Elements Rl to R3, Cl and Al within the shaded boundary 70 provide the functions of the summing circuit 42 and low-pass filter 43 in Figure 4, producing the error voltage Verr. Elements R4, R5 and A2 generate -Verr (inverted error). Amplifiers A3 and A4 operate as comparators, generating digital signals SR and SE, respectively, defining the sign of the reference and the sign of the error. Amplifiers A5 and A6 operate as fast comparators, respectively, comparing Verr and -Verr against a periodic voltage ramp Vrmp, and thereby producing pulse-width modulated digital signals PWA and PWB. According to the status of SR, one or other of logical AND gates Gl or G2 is enabled to pass signal PCDB. G4 also receives a logically-unconditional (clock) signal DM, which constrains the pulse width to a chosen maximum value. This ensures that Ql in the high voltage circuit means is always switched off for a sufficient time to complete the flyback portion of its switching cycle, for every required voltage and load imp~nr~ combination Also in Figure 7, gate G5, together with switch SWl, resistor network 72 and differential amplifier 74, provide the voltage levels of NG to control the required states of Q2, namely being loff'l, or "on" with a conduction proportional to Verr, or "on" in a heavily-conducting state.
Similarly, gate G6, together with switch SW2, resistor network 76 and differential amplifier 78 provide the required levels of PGB, controlling the states of Q3.
In Figure 8 it can be seen that the ramp Vrmp commences at a voltage that is offset from the comparator reference Vdcref by a small amount. When the error magnitude is smaller than this amount, no pulse is produced at PCDB. This aids in creating the "hold zones" shown in Figure 5.
Referring back to Figure 7, the reference voltage Vdeltal should be set to a level more negative than Vdcref, so that for small error magnitudes, the NG level is clamped _ 15 at VDC-. Similarly, the reference voltage Vdelta2 should be set to a level that is more positive than Vdcref, so that for small error magnitudes the PGB level is clamped at VDC+.
This clamping of NG and PGB at small error magnitude, together with the offset in the ramp voltage as mentioned above, may incidentally cause the formation of hold zones in the passive quadrants. However, the purpose of the offsets is to ensure that for sufficiently small errors, the discharge of energy from the load can be effectively prevented.
Figure 8 further illustrates the formation of PWA
and PWB from both smaller and larger examples of the error voltage, respectively labelled Verr(l) and Verr(2) and the form of the control signals NG, PCDB and PGB, for the large and small error examples Verr(l) and Verr(2).
Figures 9a and 9b illustrate possible implement-ations of the connection switches network. In both figures, Sl is a solid-state switch, providing the same functions as Sl in Figure 1. In general, solid-state switches are convenient when the closed-circuit resistance is not required to be very low. Kl and K2 are metallic relays. In Figure 9a, a symmetrical configuration of Kl and K2 provides signalling functions 1, 2, 3, 4, 5, and 7 as listed in Table 1, but excludes normal coin signalling, listed as number 6, because it is not possible to open-circuit the Ring lead while the high voltage circuit means is active. In Figure 9b, relays Kl and K2 are connected in an offset manner, that provides the functions 1, 2, 3, 4, 5, and 6, but not the alternate form of coin signalling, listed as number 7.
The optional functions of S7 and S8 in Figure 1, - listed as applications 8 and 9 in Table 1, are not provided in either of the above configurations. Table 3 shows the available operating modes and corresponding switch and relay states for both configurations.
----- Figure 9a ---- ---- Figure 9b ----# S 1 K 1 K2 HVC S 1 K 1 K2 HVC TELEPHONY APPLICATION
C - - inactive C - - inactive Loop Idle or DC feed (LDC on Tip,Rin~) 2 - - - active - - - active Loop Idle or DC feed (LDC on Tip,Rin~) 3 C E - inactive C E - inactive Ground Start (Tip open, LDC on Rin~) 4 C E - active C E - active Signqlling on Tip (HVC on Tip, LDC on Rin~) -- Not available-- C E E active Coin signqlling on Tip (HVC on Tip, Rin~ open) 6 C - E active C - E ac~ive Signqlli~g on Ring (HVC on Rin~, LDC on Tip) 7 C E E acti ve -- Not available -- Simple~c Coin sign, lling (HVC on both Tip & Rin~) Definition of symbols:
- - switch S 1 open, or relay Kn not energized C - switch Sl closed E ~ relay Kn energized
Claims (15)
1. A high voltage converter for providing a power to a load from a DC voltage source, by load connection lines comprising:
line driver circuit means to be connected to the said DC voltage source for providing a line drive output;
high voltage circuit means to be connected to the said DC voltage source for providing a high voltage output; and connection switch means for selectively connecting the said line driver circuit means and the said high voltage circuit means to the said load connection lines for providing the said line drive output, the said high voltage output or a combination thereof, the said high voltage circuit means in turn comprising:
a flyback transformer having a primary winding and two secondary windings;
a primary transistor switch connected to the said primary winding for supplying the pulsed power thereto from the said DC voltage source in a controlled pulsing manner;
a secondary transistor switch and diode combination connected to each of the said two secondary windings for controlling the flow of the power generated therein as the result of the power supplied to the said primary winding; and each of the said secondary transistor switches is turned on and off in a controlled manner so that a high voltage output of a specific waveform is produced.
line driver circuit means to be connected to the said DC voltage source for providing a line drive output;
high voltage circuit means to be connected to the said DC voltage source for providing a high voltage output; and connection switch means for selectively connecting the said line driver circuit means and the said high voltage circuit means to the said load connection lines for providing the said line drive output, the said high voltage output or a combination thereof, the said high voltage circuit means in turn comprising:
a flyback transformer having a primary winding and two secondary windings;
a primary transistor switch connected to the said primary winding for supplying the pulsed power thereto from the said DC voltage source in a controlled pulsing manner;
a secondary transistor switch and diode combination connected to each of the said two secondary windings for controlling the flow of the power generated therein as the result of the power supplied to the said primary winding; and each of the said secondary transistor switches is turned on and off in a controlled manner so that a high voltage output of a specific waveform is produced.
2. The high voltage converter, according to claim 1, further comprising:
power control circuit means for providing control signals to the said transistor switches.
power control circuit means for providing control signals to the said transistor switches.
3. The high voltage converter, according to claim 2, wherein one of the said control signals is a high frequency pulsing signal and is applied to the said primary transistor switch to turn the same to conducting so that the said pulsed power is supplied to the said primary winding in the controlled pulsing manner.
4. The high voltage converter, according to claim 3, wherein the others of the said control signals are applied to the said secondary transistor switches so as to control the flow of power between the said high voltage circuit means and the said load connection lines.
5. The high voltage converter, according to claim 4, wherein:
the said secondary transistor switches are each controlled by the said control signals in such a manner that when one is conducting, the other is non-conducting.
the said secondary transistor switches are each controlled by the said control signals in such a manner that when one is conducting, the other is non-conducting.
6. The high voltage converter, according to claim 5, wherein:
the conduction of the said conducting secondary transistor switch is variable.
the conduction of the said conducting secondary transistor switch is variable.
7. The high voltage converter, according to claim 4, wherein:
the said line drive circuit means is connected to the said connection switch means which in turn is connected to the load connection line;
the said power control circuit means further provides switch control signals; and the said connection switch means comprise a plurality of on/off switches operative in response to the said switch control signals.
the said line drive circuit means is connected to the said connection switch means which in turn is connected to the load connection line;
the said power control circuit means further provides switch control signals; and the said connection switch means comprise a plurality of on/off switches operative in response to the said switch control signals.
8. The high voltage converter, according to claim 7, wherein the said primary transistor switch and the said primary winding are connected in series to the said DC
voltage source, and the said secondary transistor switches and diodes and the said secondary windings are connected in a loop.
voltage source, and the said secondary transistor switches and diodes and the said secondary windings are connected in a loop.
9. The high voltage converter, according to claim 8, wherein a capacitor is provided between a point connecting the said two secondary windings and one of the two polarities of the said DC voltage source, the said point being further connected to the said connection switch means for providing the said high voltage output thereto.
10. The high voltage converter according to claim 9, wherein the said high voltage circuit means further comprises an overcurrent detection means for detecting an overcurrent which may flow out of the said DC voltage source.
11. The high voltage converter, according to claim 10, further comprising a programmable load and command means connected to the said power control circuit means for providing programmed reference signals and the said power control circuit means further comprise error detecting means for generating error signals in response to the said high voltage output with respect to the said programmed reference signals.
12. The high voltage converter, according to claim 7, wherein the said connection switch means comprise at least two sets of metallic relay switches and a solid-state switch, all operative in response to the said switch control signals.
13. The high voltage converter, according to claim 12, wherein the said two sets of metallic relay switches are arranged in an offset manner.
14. The high voltage converter, according to claim 6, further comprising a programmable load and command means connected to the said power control circuit means for providing programmed reference signals and the said power control circuit means further comprise error detecting means for generating error signals in response to the said high voltage output with respect to the said programmed reference signals.
15. The high voltage converter, according to claim 13, further comprising a programmable load and command means connected to the said power control circuit means for providing programmed reference signals and the said power control circuit means further comprise error detecting means for generating error signals in response to the said high voltage output with respect to the said programmed reference signals.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/648,776 US5103387A (en) | 1991-01-31 | 1991-01-31 | High voltage converter |
| US07/648,776 | 1991-01-31 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2059055A1 CA2059055A1 (en) | 1992-08-01 |
| CA2059055C true CA2059055C (en) | 1997-02-04 |
Family
ID=24602191
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002059055A Expired - Fee Related CA2059055C (en) | 1991-01-31 | 1992-01-08 | High voltage converter |
Country Status (2)
| Country | Link |
|---|---|
| US (2) | US5103387A (en) |
| CA (1) | CA2059055C (en) |
Families Citing this family (54)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5511118A (en) * | 1991-01-31 | 1996-04-23 | Northern Telecom Limited | Method of providing d.c. feed to a telephone line |
| US5321596A (en) * | 1991-03-25 | 1994-06-14 | Raynet Corporation | DC/DC/AC power supply for a subscriber interphase unit |
| US5521977A (en) * | 1993-10-29 | 1996-05-28 | Teltrend Inc. | High density telephone network interface unit |
| CN1049747C (en) * | 1994-02-23 | 2000-02-23 | 西铁城时计株式会社 | AC driving device |
| US5809068A (en) * | 1994-05-20 | 1998-09-15 | Multi-Tech Systems, Inc. | PCMCIA modem |
| US5539820A (en) * | 1994-10-06 | 1996-07-23 | Northern Telecom Limited | Protection of active telephone line interface circuits |
| US5619567A (en) * | 1994-10-31 | 1997-04-08 | Advanced Micro Devices | Variable DC feed characteristic in a subscriber line interface circuit |
| US5636274A (en) * | 1995-01-13 | 1997-06-03 | Harris Corp. | Switch controller and method |
| US5960075A (en) * | 1995-02-16 | 1999-09-28 | Northern Telecom Limited | Switchmode power converters for telephone subscriber line interface circuits |
| US5740241A (en) * | 1995-05-12 | 1998-04-14 | Carrier Access Corporation | T1 channel bank control process and apparatus |
| US5638440A (en) * | 1995-06-07 | 1997-06-10 | Advanced Micro Devices, Inc. | Protection circuit for telephone systems |
| US5636273A (en) * | 1995-06-07 | 1997-06-03 | Advanced Micro Devices Inc | Integrated ring detection circuit and power cross detection circuit with persistence timers |
| JP2845181B2 (en) * | 1995-09-22 | 1999-01-13 | 日本電気株式会社 | Subscriber circuit |
| US5721774A (en) * | 1995-12-15 | 1998-02-24 | Lucent Technologies Inc. | Longitudinally balanced, dual voltage line-feed circuit |
| US5663878A (en) * | 1996-03-21 | 1997-09-02 | Unitrode Corporation | Apparatus and method for generating a low frequency AC signal |
| US5854839A (en) * | 1996-05-10 | 1998-12-29 | Lucent Technologies Inc. | Dual voltage, self-monitoring line circuit |
| DE19623827C1 (en) * | 1996-06-14 | 1998-01-08 | Siemens Ag | Electronic speech circuitry |
| KR19990071636A (en) * | 1996-09-26 | 1999-09-27 | 요트.게.아. 롤페즈 | Power management methods for feeder circuits, remote communication devices and multiple direct current tilts |
| US6700975B1 (en) | 1996-11-08 | 2004-03-02 | Telefonaktiebolaget Lm Ericsson (Publ) | Subscriber line interface circuit |
| SE507920C2 (en) * | 1996-11-08 | 1998-07-27 | Ericsson Telefon Ab L M | line circuit |
| US7269034B2 (en) | 1997-01-24 | 2007-09-11 | Synqor, Inc. | High efficiency power converter |
| US6377681B1 (en) * | 1998-04-01 | 2002-04-23 | National Semiconductor Corporation | Signal line driving circuit with self-controlled power dissipation |
| WO1999053627A1 (en) | 1998-04-10 | 1999-10-21 | Chrimar Systems, Inc. Doing Business As Cms Technologies | System for communicating with electronic equipment on a network |
| US6480510B1 (en) | 1998-07-28 | 2002-11-12 | Serconet Ltd. | Local area network of serial intelligent cells |
| US6115469A (en) * | 1998-08-25 | 2000-09-05 | Unitrode Corporation | Telephone line ring signal and DC power generator |
| AU6139199A (en) * | 1998-09-11 | 2000-04-03 | Spectrx, Inc. | Multi-modal optical tissue diagnostic system |
| US6748078B1 (en) * | 1998-12-18 | 2004-06-08 | Lucent Technologies Inc. | System and method for allocating overhead voltage in the transmission of pots and XDSL signals |
| EP1017220B1 (en) * | 1998-12-31 | 2007-05-02 | STMicroelectronics S.r.l. | Circuit for ringing signal generation for subscriber circuits |
| US6873702B1 (en) | 1998-12-31 | 2005-03-29 | Stmicroelectronics S.R.L. | Telephone subscriber system |
| DE29901322U1 (en) * | 1999-01-28 | 1999-07-08 | Melcher Ag | Voltage converter |
| US6956826B1 (en) | 1999-07-07 | 2005-10-18 | Serconet Ltd. | Local area network for distributing data communication, sensing and control signals |
| US6690677B1 (en) | 1999-07-20 | 2004-02-10 | Serconet Ltd. | Network for telephony and data communication |
| US6549616B1 (en) | 2000-03-20 | 2003-04-15 | Serconet Ltd. | Telephone outlet for implementing a local area network over telephone lines and a local area network using such outlets |
| DE10045015B4 (en) * | 2000-09-12 | 2006-01-05 | Infineon Technologies Ag | Device and method for controlling a SLIC supply voltage |
| US7450712B1 (en) * | 2000-10-21 | 2008-11-11 | Silicon Laboratories, Inc. | Low voltage sensing and control of battery referenced transistors in subscriber loop applications |
| US20050220293A1 (en) * | 2000-10-25 | 2005-10-06 | Hein Jerrell P | Subscriber loop interface circuitry with tracking battery supply |
| US20030072436A1 (en) * | 2001-10-15 | 2003-04-17 | Eckhoff Christopher D. | Subscriber line interface circuitry with modified DC feed |
| CA2360117A1 (en) * | 2001-10-24 | 2003-04-24 | Catena Networks Canada Inc. | The application of pots ringing signals without interfering with dsl signals |
| US6947554B2 (en) * | 2001-11-08 | 2005-09-20 | Motorola, Inc. | Least mean power consumption in telecommunications systems |
| US6639779B2 (en) * | 2001-12-19 | 2003-10-28 | Oneac Corporation | Frequency selective transient voltage protector |
| US7206405B2 (en) * | 2002-03-06 | 2007-04-17 | Intersil Americas Inc. | Enhanced high voltage interface for partitioned subscriber line interface circuit |
| US7003103B2 (en) * | 2002-03-06 | 2006-02-21 | Intersil Americas Inc. | Mode-dependent, multiple bias-driven battery switch for subscriber line interface circuit |
| US7050577B2 (en) * | 2002-03-06 | 2006-05-23 | Intersil Americas Inc. | Programmable subscriber line circuit partitioned into high voltage interface and digital control subsections |
| US7116778B2 (en) * | 2002-09-30 | 2006-10-03 | Silicon Laboratories, Inc. | Adaptive linefeed control for varying load on a subscriber loop |
| US20040064053A1 (en) * | 2002-09-30 | 2004-04-01 | Chang Sung K. | Diagnostic fluorescence and reflectance |
| IL154234A (en) | 2003-01-30 | 2010-12-30 | Mosaid Technologies Inc | Method and system for providing dc power on local telephone lines |
| US7027590B2 (en) * | 2003-04-28 | 2006-04-11 | Lucent Technologies Inc. | Dynamic allocation of overhead voltage to support simultaneous transmission of signals on a telecommunication line |
| IL159838A0 (en) | 2004-01-13 | 2004-06-20 | Yehuda Binder | Information device |
| US7342388B2 (en) * | 2006-06-23 | 2008-03-11 | Winbond Electronics Corporation | Low ripple line-state dependent PWM DCDC converter controllers and methods for SLIC switching load regulation |
| US8036344B2 (en) * | 2007-03-26 | 2011-10-11 | Tyco Safety Products Canada Ltd. | Alarm system providing multiple network routing, interface module and method |
| DE102010039875A1 (en) * | 2010-08-27 | 2012-03-01 | Robert Bosch Gmbh | Method and device for operating a starter of a vehicle |
| CN102902219B (en) * | 2011-07-29 | 2017-01-25 | 富泰华工业（深圳）有限公司 | Electronic device and telephone switchboard |
| US9673692B2 (en) * | 2013-03-15 | 2017-06-06 | Nxp Usa, Inc. | Application of normally closed power semiconductor devices |
| US10199950B1 (en) | 2013-07-02 | 2019-02-05 | Vlt, Inc. | Power distribution architecture with series-connected bus converter |
Family Cites Families (22)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH586983A5 (en) * | 1974-12-23 | 1977-04-15 | Ibm | |
| CH604454A5 (en) * | 1976-12-10 | 1978-09-15 | Siemens Ag Albis | Telephone call signal circuit |
| US4056689A (en) * | 1977-01-05 | 1977-11-01 | Bell Telephone Laboratories, Incorporated | Telephone subscriber line circuit |
| GB1583634A (en) * | 1977-03-02 | 1981-01-28 | Int Standard Electric Corp | Subscriber line/trunk circuit |
| US4315106A (en) * | 1979-11-28 | 1982-02-09 | International Telephone And Telegraph Corporation | Apparatus for regulating current supplied to a telephone line signal of the type employed in digital telephone systems |
| GB2065418B (en) * | 1979-12-06 | 1984-02-15 | Standard Telephones Cables Ltd | Telephone line feed |
| US4317963A (en) * | 1980-09-22 | 1982-03-02 | International Telephone And Telegraph Corporation | Subscriber line interface circuit utilizing impedance synthesizer and shared voltage source for loop current regulation control |
| US4355209A (en) * | 1980-12-29 | 1982-10-19 | Gte Automatic Electric Labs Inc. | Programmable line circuit |
| CA1157175A (en) * | 1981-02-20 | 1983-11-15 | Mitel Corporation | Power saving line circuit |
| US4431868A (en) * | 1981-07-09 | 1984-02-14 | International Telephone And Telegraph Corporation | Solid state telephone line interface circuit with ringing capability |
| US4399499A (en) * | 1981-12-18 | 1983-08-16 | Gte Automatic Electric Labs Inc. | Bi-lateral four quadrant power converter |
| US4419542A (en) * | 1982-05-17 | 1983-12-06 | Bell Telephone Laboratories, Incorporated | Battery feed circuit |
| US4674119A (en) * | 1984-04-10 | 1987-06-16 | Itt Corporation | Wide-band high voltage amplifier for telephone exchange subscriber line interface utilizing low voltage control circuitry |
| US4716514A (en) * | 1984-12-13 | 1987-12-29 | Unitrode Corporation | Synchronous power rectifier |
| CA1247708A (en) * | 1985-10-28 | 1988-12-28 | Stanley D. Rosenbaum | Amplifier with double rail output |
| US4761812A (en) * | 1985-12-10 | 1988-08-02 | U.S. Holding Company, Inc. | Constant power telephone line circuit |
| AU589718B2 (en) * | 1985-12-20 | 1989-10-19 | Alcatel N.V. | Line circuit |
| CA1258930A (en) * | 1986-12-24 | 1989-08-29 | Reinhard Rosch | Active impedance line feed circuit |
| JPS6469264A (en) * | 1987-09-10 | 1989-03-15 | Motorola Japan | Dc/dc converter |
| US4882664A (en) * | 1988-06-08 | 1989-11-21 | Rane Corporation | Synchronous modulation circuit |
| US4945465A (en) * | 1988-09-15 | 1990-07-31 | U.S. Philips Corporation | Switched-mode power supply circuit |
| US5113426A (en) * | 1989-01-19 | 1992-05-12 | Fujitsu Limited | Ground fault detector |
-
1991
- 1991-01-31 US US07/648,776 patent/US5103387A/en not_active Expired - Fee Related
-
1992
- 1992-01-08 CA CA002059055A patent/CA2059055C/en not_active Expired - Fee Related
- 1992-04-02 US US07/862,478 patent/US5323461A/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| CA2059055A1 (en) | 1992-08-01 |
| US5323461A (en) | 1994-06-21 |
| US5103387A (en) | 1992-04-07 |
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| Date | Code | Title | Description |
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| EEER | Examination request | ||
| MKLA | Lapsed |