WO2000070736A1 - Method and apparatus for converting a dc voltage to an ac voltage - Google Patents

Method and apparatus for converting a dc voltage to an ac voltage Download PDF

Info

Publication number
WO2000070736A1
WO2000070736A1 PCT/US2000/012921 US0012921W WO0070736A1 WO 2000070736 A1 WO2000070736 A1 WO 2000070736A1 US 0012921 W US0012921 W US 0012921W WO 0070736 A1 WO0070736 A1 WO 0070736A1
Authority
WO
WIPO (PCT)
Prior art keywords
power
inverter
power supply
output
load
Prior art date
Application number
PCT/US2000/012921
Other languages
French (fr)
Other versions
WO2000070736A9 (en
Inventor
David E. Reilly
Original Assignee
American Power Conversion, Inc.
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by American Power Conversion, Inc. filed Critical American Power Conversion, Inc.
Priority to EP00930608A priority Critical patent/EP1186094B1/en
Priority to DE2000622346 priority patent/DE60022346T2/en
Priority to AT00930608T priority patent/ATE303668T1/en
Priority to JP2000619079A priority patent/JP4651824B2/en
Priority to AU48400/00A priority patent/AU770941B2/en
Priority to CA 2373762 priority patent/CA2373762C/en
Publication of WO2000070736A1 publication Critical patent/WO2000070736A1/en
Publication of WO2000070736A9 publication Critical patent/WO2000070736A9/en

Links

Classifications

    • 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
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5383—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a self-oscillating arrangement
    • H02M7/53832—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a self-oscillating arrangement in a push-pull arrangement
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J9/00—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting
    • H02J9/04—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source
    • H02J9/06—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems
    • H02J9/062—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems for AC powered loads
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Definitions

  • Embodiments of the present invention are directed generally to a method and an apparatus for converting a DC voltage to an AC voltage. More specifically, embodiments of the present invention are directed to methods and apparatus for converting DC voltages to AC voltages using resonant bridge inverter circuits in devices such as uninterruptible power supplies. Background of the Invention
  • UPSs uninterruptible power supplies
  • Fig. 1 shows a typical prior art UPS 10 used to provide regulated uninterrupted power.
  • the UPS 10 includes an input filter/surge protector 12, a transfer switch 14, a controller 16, a battery 18, a battery charger 19, an inverter 20, and a DC-DC converter 23.
  • the UPS also includes an input 24 for coupling to an AC power source and an outlet 26 for coupling to a load.
  • the UPS 10 operates as follows.
  • the filter/surge protector 12 receives input AC power from the AC power source through the input 24, filters the input AC power and provides filtered AC power to the transfer switch and the battery charger.
  • the transfer switch 14 receives the AC power from the filter/surge protector 12 and also receives AC power from the inverter 20.
  • the controller 16 determines whether the AC power available from the filter/surge protector is within predetermined tolerances, and if so, controls the transfer switch to provide the AC power from the filter/surge protector to the outlet 26. If the AC power from the rectifier is not within the predetermined tolerances, which may occur because of "brown out,” “high line,” or “black out” conditions, or due to power surges, then the controller controls the transfer switch to provide the AC power from the inverter 20.
  • the DC-DC converter 23 is an optional component that converts the output of the battery to a voltage that is compatible with the inverter. Depending on the particular inverter and battery used the inverter may be operatively coupled to the battery either directly or through a DC-DC converter.
  • the inverter 20 of the prior art UPS 10 receives DC power from the DC-DC converter 23, converts the DC voltage to AC voltage, and regulates the AC voltage to predetermined specifications.
  • the inverter 20 provides the regulated AC voltage to the transfer switch.
  • the UPS 10 can provide power to the load during brief power source "dropouts" or for extended power outages.
  • a typical prior art inverter circuit 100 is shown in Fig. 2 coupled to a DC voltage source 18a and coupled to a typical load 126 comprising a load resistor 128 and a load capacitor 130.
  • the DC voltage source 18a may be a battery, or may include a battery 18 coupled to a DC-DC converter 23 and a capacitor 25 as shown in Fig. 2 A.
  • Typical loads have a capacitive component due to the presence of an EMI filter in the load.
  • the inverter circuit 100 includes four switches SI, S2, S3 and S4.
  • Each of the switches is implemented using power MOSFET devices which consist of a transistor 106, 112, 118, 124 having an intrinsic diode 104, 110, 116, and 122.
  • Each of the transistors 106, 112, 118 and 124 has a gate, respectively 107, 109, 111 and 113.
  • each of the switches SI - S4 can be controlled using a control signal input to its gate.
  • Fig. 3 provides timing waveforms for the switches to generate an output AC voltage waveform Vout (also shown in Fig. 3) across the capacitor 130 and the resistor 128.
  • a major drawback of the prior art inverter circuit 100 is that for loads having a capacitive component, a significant amount of power is dissipated as the load capacitance is charged and discharged during each half-cycle of the AC waveform. This power is absorbed by the switches SI, S2, S3, S4, which typically requires the switches to be mounted to relatively large heat sinks. The power dissipation issue becomes greater for high voltage systems, wherein the energy required to charge the load capacitance is greater. The dissipation of power in the switches dramatically reduces the efficiency of the inverter, and accordingly, reduces the run-time of the battery 18 in the UPS 10. Temperature rise of the switches also becomes a large concern.
  • the present invention features an uninterruptible power supply for providing AC power to a load.
  • the uninterruptible power supply includes an input to receive AC power from an AC power source, an output that provides AC power, a DC voltage source that provides DC power, the DC voltage source having an energy storage device, and an inverter operatively coupled to the DC voltage source to receive DC power and to provide AC power.
  • the inverter includes first and second output nodes to provide AC power to the load, first and second input nodes to receive DC power from the DC voltage source, a resonant element having a first terminal and a second terminal, the second terminal being electrically coupled to the first output node, a first switch electrically coupled between the first terminal of the resonant element and the first input node, and a set of switches operatively coupled between the first and second output nodes and the first and second input nodes and controlled to generate AC power from the DC power.
  • the uninterruptible power supply further includes a transfer switch constructed and arranged to select either the AC line or inverter power source as an output power source for the uninterruptible power supply.
  • the set of switches in the inverter can include a second switch electrically coupled between the second output node and the second input node, a third switch electrically coupled between the second output node and the first input node, a fourth switch electrically coupled between the first output node and the first input node, and a fifth switch electrically coupled between the first output node and the second input node.
  • the inverter can further include a sixth switch electrically coupled between the first terminal of the resonant element and the second input node.
  • the resonant element in the inverter may include an inductor.
  • Each of the switches may include a transistor.
  • the energy storage device can include a battery.
  • the transfer switch can be constructed and arranged to receive the AC power from the input and to receive the AC power from the inverter and to provide one of the AC power from the input and the AC power from the inverter to the load.
  • the present invention features an uninterruptible power supply for providing AC power to a load having a capacitive element.
  • the uninterruptible power supply includes an input to receive AC power from an AC power source, an output that provides AC power, a voltage source that provides DC power, the voltage source having an energy storage device, an inverter operatively coupled to the voltage source to receive DC power and having an output to provide AC power.
  • the inverter includes means for charging the capacitive element by supplying electrical current from the inverter to the load through a resonant element, means for supplying load current from the inverter after the capacitive element has been charged to a predetermined voltage, means for discharging the capacitive element through the resonant element, and means for transferring energy from the resonant element to the energy storage device.
  • the uninterruptible power supply further includes a transfer switch constructed and arranged to select one of the AC power source and the voltage source as an output power source for the uninterruptible power supply.
  • the present invention features a method of supplying an uninterruptible AC voltage to a load having a capacitive element using an uninterruptible power supply having a DC voltage source with an energy storage device.
  • the method includes steps of charging the capacitive element by supplying electrical current from the DC voltage source to the load through a resonant element in the uninterruptible power supply, supplying load current from the DC voltage source to the load after the capacitive element has been charged to a predetermined voltage, discharging the capacitive element through the resonant element, and transferring energy from the resonant element to the energy storage device in the DC voltage source.
  • the method can further include steps of receiving an AC voltage from an AC power source, selecting one of the AC power source and the DC voltage source as an output power source for the uninterruptible power supply.
  • Fig. 1 is a block diagram of a typical uninterruptible power supply
  • Fig. 2 shows a schematic diagram of a typical prior art inverter circuit
  • Fig. 2A shows a block diagram of a voltage source used with the inverter circuit of Fig. 2.
  • FIG. 3 shows timing waveforms for the inverter circuit shown in Fig. 2;
  • Fig. 4 shows a schematic diagram of an inverter circuit in accordance with one embodiment of the present invention
  • Fig. 5 shows timing waveforms for the inverter circuit shown in Fig. 4;
  • Fig. 6 illustrates a current path through the inverter of Fig. 4 during a charging mode of the inverter corresponding to a starting point of the positive half cycle of the output voltage waveform;
  • Fig. 7 illustrates a current path through the inverter of Fig. 4 during a positive half cycle of the output voltage waveform;
  • Fig. 8 illustrates a current path through the inverter of Fig. 4 during a discharging mode of the inverter at the end of the positive half cycle of the output voltage waveform; and Fig. 9 illustrates a current path through the inverter during an energy recovery mode of the inverter.
  • the inverter 200 includes MOSFET switches SI, S2, S3 and S4 of the prior art inverter 100 and includes two additional MOSFET switches S5 and S6 and an inductor 140.
  • the switches S5 and S6 are similar to switches SI - S4 and include a transistor 134, 138 having an intrinsic diode 132, 136.
  • Each of the transistors 134 and 138 has a gate 115 and 117 that is used to control the state of the transistor.
  • the switches SI - S6 are implemented using part no. IRF640 available from International Rectifier of El Segundo, CA. For 220 VAC applications, the switches may be implemented using part no. IRF730 also available from International Rectifier.
  • the inductor 140 in the 120 VAC embodiment, is implemented using a 1.5 mH inductor having a very high Bsat value to be able to withstand high peak currents without saturating. In one embodiment, the inductor is made from an El lamination structure of M-19, 18.5 mil steel having a large air gap between the E and I laminations.
  • inductors may be used with embodiments of the present invention depending upon the peak switch current and physical size of the inductor desired.
  • the transition time or time required to charge or discharge the load capacitance, should also be considered to prevent the transition time from becoming either too short or too long. If the transition time is too long, then the pulse width of the output waveform may become too long. If the transition time is too short, the peak switch currents become greater.
  • Fig. 5 provides a timing diagram of the operation of the switches SI - S6 of the inverter 200 and also provides the output voltage waveform across the load 126.
  • the switch is turned on (conducting state) and when the corresponding waveform is in the low state the switch is turned off (non-conducting state).
  • the switches are shown as being implemented using NMOS devices.
  • NMOS complementary metal-oxide-semiconductor
  • a control signal having a positive state is supplied to the gate of the device to turn the device on (conducting), while a control signal having a low state is supplied to the gate to turn the device off (non-conducting).
  • the timing diagram of each of the switches also represents the state of the control signal provided to the gate of the corresponding transistor.
  • the control signals may be provided from, for example, controller 16 of the UPS of Fig. 1 when the inverter is used in a UPS.
  • the control signals may be supplied using timing logic circuits residing within the inverter itself as is known in the art.
  • switches S4 and S5 are turned on and switches SI, S2, S3 and S6 are turned off creating a current path through the inverter 200 in the direction of arrows 150 as shown in Fig. 6. Only the components of the inverter 200 in the current path created during the first time period are shown in Fig. 6. As shown in Fig. 6, with switches S4 and S5 turned on, the inductor 140 and the load 126 are connected in series across the voltage source 18a. During the first period, the output voltage across the load Vout rises in a resonant manner from zero volts to the voltage of the voltage source 18a.
  • the output voltage Vout is prevented from rising beyond the voltage of the voltage source by the diode 104 (Fig. 7) of switch SI.
  • the diode 104 will conduct current to limit the output voltage Vout to the voltage of the voltage source.
  • switch SI is turned on and switch S5 is turned off.
  • Switches SI and S4 remain on for a second period from time tl to time t2, during which time, the load is coupled across the voltage source 18a.
  • Fig. 7 shows the current path through the inverter during the second time period. As shown in Fig, 7, load current during the second period follows arrows 154.
  • the energy that was stored in the inductor during the first time period causes the voltage across the inductor to reverse and energy in the inductor is released to a storage device in the voltage source, such as a battery or a capacitor, through a current that follows a path along arrow 156 through diode 104 of switch 1 and diode 136 of switch 6.
  • a storage device in the voltage source such as a battery or a capacitor
  • current from the energy stored in the inductor may also follow a path through the load.
  • switch S6 is turned off, and all switches remain off during a fourth time period from t3 until t4.
  • the current path through the inverter 200 during the fourth time period follows arrows 160 shown in Fig. 9.
  • the energy in the inductor 140 freewheels into the voltage source 18a through diodes 110 and 132 of S2 and S5, and the voltage across the load typically remains at zero.
  • the time from t3 until t4 is normally chosen to be long enough to permit all of the inductor energy to be transferred to the voltage source 18a.
  • switches SI and S3 are turned on to maintain a low impedance across the load to prevent any external energy from charging the output to a non-zero voltage. This is referred to as the "clamp" period.
  • all switches are again turned off and remain off for a sixth time period until time t6.
  • the negative half cycle of the AC waveform is created.
  • the negative half cycle is created in substantially the same manner as the positive half cycle described above, except that switch S3 is substituted for switch S4, switch S6 is substituted for S5 and switch S2 is substituted for SI .
  • the positive and negative half cycles then continue to be generated in an alternating manner to create an AC output voltage waveform.
  • the first time period from tO to tl is approximately 130 microseconds
  • the second time period from tl to t2 is approximately 4 milliseconds
  • the third time period from t2 to t3 is approximately 130 microseconds
  • the fourth time period from t3 to t4 is approximately 100 microseconds
  • the time period from time t4 to t5 is approximately 4.2 milliseconds
  • the time period from t5 to t6 is approximately 10 microseconds.
  • the negative half cycle of the waveform is symmetric with the positive half cycle, and accordingly, the rise time, fall time and duration of the negative half cycle are approximately equal to those of the positive half cycle.
  • switches SI and S3 are turned on to clamp the output to a low impedance.
  • switches S2 and S4 are turned on rather than switches SI and S3.
  • switches SI and S3 are turned on, however, switches S2 and S4 could be turned on in place of switches S 1 and S3.
  • the inverter 200 is used in the manner described above, to create an output AC voltage having the waveform shown in Fig. 5 from an input DC voltage using a resonance circuit.
  • the use of the resonance circuit allows the load capacitance to be charged and discharged with only a minimum power loss.
  • the only power losses incurred in the inverter 200 are due to characteristics of inverter components including the ESR of the inductor and due to series resistance of each of the switches when in the on state.
  • inverters in accordance with embodiments of the present invention do not require bulky heat sinks like inverters of the prior art, and are more efficient than inverters of the prior art.
  • the improved efficiency of inverters in accordance with embodiments of the present invention make them particularly desirable for use in uninterruptible power supplies, wherein they can extend the operating time of a UPS in battery mode, reduce the size and weight of the UPS and reduce electromagnetic emissions from the UPS.
  • inverters are described as being used with uninterruptible power supplies, for example, in place of the inverter 20 in the UPS 10 of Fig. 1.
  • inverters of the present invention may also be used with other types of uninterruptible power supplies.
  • the inverters may be used with UPSs in which an input AC voltage is converted to a DC voltage and one of the converted DC voltage and a DC voltage provided from a battery-powered DC voltage source is provided to an input of the inverter to create the AC output voltage of the UPS.
  • inverters in accordance with embodiments of the present invention may also be used in systems and devices other than uninterruptible power supplies.
  • MOSFET devices are used as the switches SI - S6.
  • each of the switches SI - S6 need not be implemented using the same type of switch.
  • an inductor is used as a resonant element in inverter circuits.
  • other devices having a complex impedance may be used in place of the inductor, however, it is desirable that any such device be primarily inductive in nature.
  • energy is returned from the inductor to the voltage source after the load capacitance has been discharged.
  • the voltage source may include a battery that receives the energy from the inductor, or the voltage source may include a storage device other than a battery, such as a capacitor, coupled in parallel across the voltage source that receives the energy.

Abstract

Embodiments of the present invention are directed to an uninterruptible power supply for providing AC power to a load. In embodiments of the present invention, the uninterruptible power supply includes an input to receive AC power from an AC power source, an output that provides AC power, a DC voltage source that provides DC power, the DC voltage source having an energy storage device, an inverter (200) operatively coupled to the DC voltage source to receive DC power and to provide AC power. The inverter includes first and second output nodes to provide AC power to the load (126), first and second input nodes to receive DC power from the DC voltage source (18a), a resonant element (140) having a first terminal and a second terminal, the second terminal being electrically coupled to the first output node, a first switch (134) electrically coupled between the first terminal of the resonant element and the first input node, and a set of switches (106, 112, 118, 124) operatively coupled between the first and second output nodes and the first and second input nodes and controlled to generate AC power from the DC power. The uninterruptible power supply further includes a transfer switch constructed and arranged to select one of the AC power source and the DC voltage source as an output power source for the uninterruptible power supply.

Description

METHOD AND APPARATUS FOR CONVERTING A DC VOLTAGE TO AN AC VOLTAGE
Field of the Invention Embodiments of the present invention are directed generally to a method and an apparatus for converting a DC voltage to an AC voltage. More specifically, embodiments of the present invention are directed to methods and apparatus for converting DC voltages to AC voltages using resonant bridge inverter circuits in devices such as uninterruptible power supplies. Background of the Invention
The use of uninterruptible power supplies (UPSs) having battery back-up systems to provide regulated, uninterrupted power for sensitive and/or critical loads, such as computer systems, and other data processing systems is well known. Fig. 1 shows a typical prior art UPS 10 used to provide regulated uninterrupted power. The UPS 10 includes an input filter/surge protector 12, a transfer switch 14, a controller 16, a battery 18, a battery charger 19, an inverter 20, and a DC-DC converter 23. The UPS also includes an input 24 for coupling to an AC power source and an outlet 26 for coupling to a load.
The UPS 10 operates as follows. The filter/surge protector 12 receives input AC power from the AC power source through the input 24, filters the input AC power and provides filtered AC power to the transfer switch and the battery charger. The transfer switch 14 receives the AC power from the filter/surge protector 12 and also receives AC power from the inverter 20. The controller 16 determines whether the AC power available from the filter/surge protector is within predetermined tolerances, and if so, controls the transfer switch to provide the AC power from the filter/surge protector to the outlet 26. If the AC power from the rectifier is not within the predetermined tolerances, which may occur because of "brown out," "high line," or "black out" conditions, or due to power surges, then the controller controls the transfer switch to provide the AC power from the inverter 20. The DC-DC converter 23 is an optional component that converts the output of the battery to a voltage that is compatible with the inverter. Depending on the particular inverter and battery used the inverter may be operatively coupled to the battery either directly or through a DC-DC converter.
The inverter 20 of the prior art UPS 10 receives DC power from the DC-DC converter 23, converts the DC voltage to AC voltage, and regulates the AC voltage to predetermined specifications. The inverter 20 provides the regulated AC voltage to the transfer switch. Depending on the capacity of the battery and the power requirements of the load, the UPS 10 can provide power to the load during brief power source "dropouts" or for extended power outages.
In typical medium power, low cost inverters, such as inverter 20 of UPS 10, the waveform of the AC voltage has a rectangular shape rather than a sinusoidal shape. A typical prior art inverter circuit 100 is shown in Fig. 2 coupled to a DC voltage source 18a and coupled to a typical load 126 comprising a load resistor 128 and a load capacitor 130. The DC voltage source 18a may be a battery, or may include a battery 18 coupled to a DC-DC converter 23 and a capacitor 25 as shown in Fig. 2 A. Typical loads have a capacitive component due to the presence of an EMI filter in the load. The inverter circuit 100 includes four switches SI, S2, S3 and S4. Each of the switches is implemented using power MOSFET devices which consist of a transistor 106, 112, 118, 124 having an intrinsic diode 104, 110, 116, and 122. Each of the transistors 106, 112, 118 and 124 has a gate, respectively 107, 109, 111 and 113. As understood by those skilled in the art, each of the switches SI - S4 can be controlled using a control signal input to its gate. Fig. 3 provides timing waveforms for the switches to generate an output AC voltage waveform Vout (also shown in Fig. 3) across the capacitor 130 and the resistor 128.
A major drawback of the prior art inverter circuit 100 is that for loads having a capacitive component, a significant amount of power is dissipated as the load capacitance is charged and discharged during each half-cycle of the AC waveform. This power is absorbed by the switches SI, S2, S3, S4, which typically requires the switches to be mounted to relatively large heat sinks. The power dissipation issue becomes greater for high voltage systems, wherein the energy required to charge the load capacitance is greater. The dissipation of power in the switches dramatically reduces the efficiency of the inverter, and accordingly, reduces the run-time of the battery 18 in the UPS 10. Temperature rise of the switches also becomes a large concern.
Summary of the Invention In embodiments of the present invention, the problems associated with power dissipation in an inverter due to capacitor charging are eliminated by providing a resonant circuit in the inverter to charge and discharge the capacitor.
In one general aspect, the present invention features an uninterruptible power supply for providing AC power to a load. The uninterruptible power supply includes an input to receive AC power from an AC power source, an output that provides AC power, a DC voltage source that provides DC power, the DC voltage source having an energy storage device, and an inverter operatively coupled to the DC voltage source to receive DC power and to provide AC power. The inverter includes first and second output nodes to provide AC power to the load, first and second input nodes to receive DC power from the DC voltage source, a resonant element having a first terminal and a second terminal, the second terminal being electrically coupled to the first output node, a first switch electrically coupled between the first terminal of the resonant element and the first input node, and a set of switches operatively coupled between the first and second output nodes and the first and second input nodes and controlled to generate AC power from the DC power. The uninterruptible power supply further includes a transfer switch constructed and arranged to select either the AC line or inverter power source as an output power source for the uninterruptible power supply.
The set of switches in the inverter can include a second switch electrically coupled between the second output node and the second input node, a third switch electrically coupled between the second output node and the first input node, a fourth switch electrically coupled between the first output node and the first input node, and a fifth switch electrically coupled between the first output node and the second input node. The inverter can further include a sixth switch electrically coupled between the first terminal of the resonant element and the second input node. The resonant element in the inverter may include an inductor. Each of the switches may include a transistor. The energy storage device can include a battery. The transfer switch can be constructed and arranged to receive the AC power from the input and to receive the AC power from the inverter and to provide one of the AC power from the input and the AC power from the inverter to the load. In another general aspect, the present invention features an uninterruptible power supply for providing AC power to a load having a capacitive element. The uninterruptible power supply includes an input to receive AC power from an AC power source, an output that provides AC power, a voltage source that provides DC power, the voltage source having an energy storage device, an inverter operatively coupled to the voltage source to receive DC power and having an output to provide AC power. The inverter includes means for charging the capacitive element by supplying electrical current from the inverter to the load through a resonant element, means for supplying load current from the inverter after the capacitive element has been charged to a predetermined voltage, means for discharging the capacitive element through the resonant element, and means for transferring energy from the resonant element to the energy storage device. The uninterruptible power supply further includes a transfer switch constructed and arranged to select one of the AC power source and the voltage source as an output power source for the uninterruptible power supply.
In another general aspect, the present invention features a method of supplying an uninterruptible AC voltage to a load having a capacitive element using an uninterruptible power supply having a DC voltage source with an energy storage device. The method includes steps of charging the capacitive element by supplying electrical current from the DC voltage source to the load through a resonant element in the uninterruptible power supply, supplying load current from the DC voltage source to the load after the capacitive element has been charged to a predetermined voltage, discharging the capacitive element through the resonant element, and transferring energy from the resonant element to the energy storage device in the DC voltage source. The method can further include steps of receiving an AC voltage from an AC power source, selecting one of the AC power source and the DC voltage source as an output power source for the uninterruptible power supply.
Brief Description of the Drawings For a better understanding of the present invention, reference is made to the drawings which are incorporated herein by reference and in which:
Fig. 1 is a block diagram of a typical uninterruptible power supply; Fig. 2 shows a schematic diagram of a typical prior art inverter circuit; Fig. 2A shows a block diagram of a voltage source used with the inverter circuit of Fig. 2.
Fig. 3 shows timing waveforms for the inverter circuit shown in Fig. 2; Fig. 4 shows a schematic diagram of an inverter circuit in accordance with one embodiment of the present invention;
Fig. 5 shows timing waveforms for the inverter circuit shown in Fig. 4; Fig. 6 illustrates a current path through the inverter of Fig. 4 during a charging mode of the inverter corresponding to a starting point of the positive half cycle of the output voltage waveform; Fig. 7 illustrates a current path through the inverter of Fig. 4 during a positive half cycle of the output voltage waveform;
Fig. 8 illustrates a current path through the inverter of Fig. 4 during a discharging mode of the inverter at the end of the positive half cycle of the output voltage waveform; and Fig. 9 illustrates a current path through the inverter during an energy recovery mode of the inverter.
Detailed Description One embodiment of an inverter 200 in accordance with the present mvention will now be described with reference to Fig. 4 which shows a schematic diagram of the inverter 200 coupled to the voltage source 18a and the load 126. The inverter 200 includes MOSFET switches SI, S2, S3 and S4 of the prior art inverter 100 and includes two additional MOSFET switches S5 and S6 and an inductor 140. In one embodiment, the switches S5 and S6 are similar to switches SI - S4 and include a transistor 134, 138 having an intrinsic diode 132, 136. Each of the transistors 134 and 138 has a gate 115 and 117 that is used to control the state of the transistor.
In one embodiment that provides an output of 120 VAC, 400 VA, 25 amps peak current to the load from an input to the inverter of approximately 170 VDC, the switches SI - S6 are implemented using part no. IRF640 available from International Rectifier of El Segundo, CA. For 220 VAC applications, the switches may be implemented using part no. IRF730 also available from International Rectifier. The inductor 140, in the 120 VAC embodiment, is implemented using a 1.5 mH inductor having a very high Bsat value to be able to withstand high peak currents without saturating. In one embodiment, the inductor is made from an El lamination structure of M-19, 18.5 mil steel having a large air gap between the E and I laminations. Other values of inductors may be used with embodiments of the present invention depending upon the peak switch current and physical size of the inductor desired. In selecting an inductor for use, the transition time, or time required to charge or discharge the load capacitance, should also be considered to prevent the transition time from becoming either too short or too long. If the transition time is too long, then the pulse width of the output waveform may become too long. If the transition time is too short, the peak switch currents become greater.
The operation of the inverter 200 to provide AC power to the load will now be described with reference to Figs 5 - 9. Fig. 5 provides a timing diagram of the operation of the switches SI - S6 of the inverter 200 and also provides the output voltage waveform across the load 126. In the timing diagram of Fig. 5, for each of the switches SI - S6, when the corresponding waveform is in the high state, the switch is turned on (conducting state) and when the corresponding waveform is in the low state the switch is turned off (non-conducting state).
In the inverter 200, the switches are shown as being implemented using NMOS devices. As known by those skilled in the art, for an NMOS device, a control signal having a positive state is supplied to the gate of the device to turn the device on (conducting), while a control signal having a low state is supplied to the gate to turn the device off (non-conducting). Accordingly, the timing diagram of each of the switches also represents the state of the control signal provided to the gate of the corresponding transistor. In embodiments of the present invention, the control signals may be provided from, for example, controller 16 of the UPS of Fig. 1 when the inverter is used in a UPS. Alternatively, the control signals may be supplied using timing logic circuits residing within the inverter itself as is known in the art. During a first time period from tO to tl in Fig. 5, switches S4 and S5 are turned on and switches SI, S2, S3 and S6 are turned off creating a current path through the inverter 200 in the direction of arrows 150 as shown in Fig. 6. Only the components of the inverter 200 in the current path created during the first time period are shown in Fig. 6. As shown in Fig. 6, with switches S4 and S5 turned on, the inductor 140 and the load 126 are connected in series across the voltage source 18a. During the first period, the output voltage across the load Vout rises in a resonant manner from zero volts to the voltage of the voltage source 18a. The output voltage Vout is prevented from rising beyond the voltage of the voltage source by the diode 104 (Fig. 7) of switch SI. The diode 104 will conduct current to limit the output voltage Vout to the voltage of the voltage source. Once the output voltage Vout reaches the voltage of the voltage source (or shortly thereafter), at time tl, switch SI is turned on and switch S5 is turned off. Switches SI and S4 remain on for a second period from time tl to time t2, during which time, the load is coupled across the voltage source 18a. Fig. 7 shows the current path through the inverter during the second time period. As shown in Fig, 7, load current during the second period follows arrows 154. Also during the second time period, the energy that was stored in the inductor during the first time period causes the voltage across the inductor to reverse and energy in the inductor is released to a storage device in the voltage source, such as a battery or a capacitor, through a current that follows a path along arrow 156 through diode 104 of switch 1 and diode 136 of switch 6. In addition, depending upon the load impedance, current from the energy stored in the inductor may also follow a path through the load.
During a third time period from time t2 to time t3, the voltage across the load is returned to zero. At time t2, switches SI and S4 are turned off to disconnect the load from the voltage source and switch S6 is turned on to place the inductor effectively across the load as shown in Fig. 8. During the third time period, energy stored in the load capacitor 130 is transferred to the inductor 140, and the voltage across the load decreases to zero. The output voltage Vout is prevented from going negative by diode 110 (Fig. 9) of switch S2. The diode 110 will conduct current to limit the output voltage to zero.
At time t3 switch S6 is turned off, and all switches remain off during a fourth time period from t3 until t4. The current path through the inverter 200 during the fourth time period follows arrows 160 shown in Fig. 9. During the fourth time period, the energy in the inductor 140 freewheels into the voltage source 18a through diodes 110 and 132 of S2 and S5, and the voltage across the load typically remains at zero. The time from t3 until t4 is normally chosen to be long enough to permit all of the inductor energy to be transferred to the voltage source 18a.
During a fifth time period from t4 to t5, switches SI and S3 are turned on to maintain a low impedance across the load to prevent any external energy from charging the output to a non-zero voltage. This is referred to as the "clamp" period. At time t5, all switches are again turned off and remain off for a sixth time period until time t6.
Beginning at time t6, and continuing until time t9 the negative half cycle of the AC waveform is created. The negative half cycle is created in substantially the same manner as the positive half cycle described above, except that switch S3 is substituted for switch S4, switch S6 is substituted for S5 and switch S2 is substituted for SI . The positive and negative half cycles then continue to be generated in an alternating manner to create an AC output voltage waveform.
In one embodiment of the present invention, in an inverter designed to generate 60 Hz voltage waveforms, the first time period from tO to tl is approximately 130 microseconds, the second time period from tl to t2 is approximately 4 milliseconds, the third time period from t2 to t3 is approximately 130 microseconds, the fourth time period from t3 to t4 is approximately 100 microseconds, the time period from time t4 to t5 is approximately 4.2 milliseconds, and the time period from t5 to t6 is approximately 10 microseconds. In this embodiment, the negative half cycle of the waveform is symmetric with the positive half cycle, and accordingly, the rise time, fall time and duration of the negative half cycle are approximately equal to those of the positive half cycle. In embodiments described above, during the clamp period from t4 to t5 after a positive half cycle and during the clamp period from tlO to tl 1 after a negative half cycle, switches SI and S3 are turned on to clamp the output to a low impedance. In another embodiment of the present invention, during the clamp period from t4 to t5 following a positive half cycle, switches S2 and S4 are turned on rather than switches SI and S3. In this embodiment, as in the previously described embodiments, during the clamp period from tlO to tl 1, switches SI and S3 are turned on, however, switches S2 and S4 could be turned on in place of switches S 1 and S3. Turning on S2 instead of SI after the positive half cycle is beneficial in that the voltage drop across S2 is lowered, and since switch S2 is in the energy recovery path for inductor 140, the lower voltage drop increases circuit efficiency. In embodiments of the present invention, the inverter 200, is used in the manner described above, to create an output AC voltage having the waveform shown in Fig. 5 from an input DC voltage using a resonance circuit. The use of the resonance circuit allows the load capacitance to be charged and discharged with only a minimum power loss. The only power losses incurred in the inverter 200 are due to characteristics of inverter components including the ESR of the inductor and due to series resistance of each of the switches when in the on state. Thus, inverters in accordance with embodiments of the present invention, do not require bulky heat sinks like inverters of the prior art, and are more efficient than inverters of the prior art. The improved efficiency of inverters in accordance with embodiments of the present invention make them particularly desirable for use in uninterruptible power supplies, wherein they can extend the operating time of a UPS in battery mode, reduce the size and weight of the UPS and reduce electromagnetic emissions from the UPS.
In embodiments of the present invention described above, inverters are described as being used with uninterruptible power supplies, for example, in place of the inverter 20 in the UPS 10 of Fig. 1. As understood by those skilled in the art, inverters of the present invention may also be used with other types of uninterruptible power supplies. For example, the inverters may be used with UPSs in which an input AC voltage is converted to a DC voltage and one of the converted DC voltage and a DC voltage provided from a battery-powered DC voltage source is provided to an input of the inverter to create the AC output voltage of the UPS. In addition, as understood by those skilled in the art, inverters in accordance with embodiments of the present invention may also be used in systems and devices other than uninterruptible power supplies. In the inverter 200 described above, MOSFET devices are used as the switches SI - S6.
As understood by those skilled in the art, a number of other electrical or mechanical switches, such as IGBT's with integral rectifiers, or bipolar transistors having a diode across the C-E junction, may be used to provide the functionality of the switches. Further, in embodiments of the present invention, each of the switches SI - S6 need not be implemented using the same type of switch.
In embodiments of the invention discussed above, an inductor is used as a resonant element in inverter circuits. As understood by one skilled in the art, other devices having a complex impedance may be used in place of the inductor, however, it is desirable that any such device be primarily inductive in nature. In the embodiments of the present invention described above, energy is returned from the inductor to the voltage source after the load capacitance has been discharged. As understood by those skilled in the art, the voltage source may include a battery that receives the energy from the inductor, or the voltage source may include a storage device other than a battery, such as a capacitor, coupled in parallel across the voltage source that receives the energy.
Having thus described at least one illustrative embodiment of the invention, various alterations, modifications and improvements will readily occur to those skilled in the art. Such alterations, modifications and improvements are intended to be within the scope and spirit of the invention. Accordingly, the foregoing description is by way of example only and is not intended as limiting. The invention's limit is defined only in the following claims and the equivalents thereto.
What is claimed is:

Claims

1. An uninterruptible power supply for providing AC power to a load, the uninterruptible power supply comprising: an input to receive AC power from an AC power source; an output that provides AC power; a DC voltage source that provides DC power, the DC voltage source having an energy storage device; an inverter operatively coupled to the DC voltage source to receive DC power and to provide AC power, the inverter including: first and second output nodes to provide AC power to the load; first and second input nodes to receive DC power from the DC voltage source; a resonant element having a first terminal and a second terminal, the second terminal being electrically coupled to the first output node; a first switch electrically coupled between the first terminal of the resonant element and the first input node; and a set of switches operatively coupled between the first and second output nodes and the first and second input nodes and controlled to generate AC power from the DC power; and a transfer switch constructed and arranged to select one of the AC power source and the
DC voltage source as an output power source for the uninterruptible power supply.
2. The uninterruptible power supply of claim 1, wherein the set of switches includes: a second switch electrically coupled between the second output node and the second input node; a third switch electrically coupled between the second output node and the first input node; a fourth switch electrically coupled between the first output node and the first input node; and a fifth switch electrically coupled between the first output node and the second input node.
3. The uninterruptible power supply of claim 2, wherein the inverter further includes: a sixth switch electrically coupled between the first terminal of the resonant element and the second input node.
4. The uninterruptible power supply of claim 3, wherein the resonant element includes an inductor.
5. The uninterruptible power supply of claim 4, wherein each of the switches includes a transistor.
6. The uninterruptible power supply of claim 5, wherein the energy storage device includes a battery.
7. The uninterruptible power supply of claim 6, wherein the transfer switch is constructed and arranged to receive the AC power from the input and to receive the AC power from the inverter and to provide one of the AC power from the input and the AC power from the inverter to the load.
8. The uninterruptible power supply of claim 1, wherein the resonant element includes an inductor.
9. The uninterruptible power supply of claim 1, wherein each of the switches includes a transistor.
10. The uninterruptible power supply of claim 1, wherein the energy storage device includes a battery.
11. The uninterruptible power supply of claim 1 , wherein the transfer switch is constructed and arranged to receive the AC power from the input and to receive the AC power from the inverter and to provide one of the AC power from the input and the AC power from the output of the inverter to the load.
12. An uninterruptible power supply for providing AC power to a load having a capacitive element, the uninterruptible power supply comprising: an input to receive AC power from an AC power source; an output that provides AC power; a voltage source that provides DC power, the voltage source having an energy storage device; an inverter operatively coupled to the voltage source to receive DC power and having an output to provide AC power, the inverter including: means for charging the capacitive element by supplying electrical current from the inverter to the load through a resonant element; means for supplying load current from the inverter after the capacitive element has been charged to a predetermined voltage; means for discharging the capacitive element through the resonant element; and means for transferring energy from the resonant element to the energy storage device; and a transfer switch constructed and arranged to select one of the AC power source and the voltage source as an output power source for the uninterruptible power supply.
13. The uninterruptible power supply of claim 12, wherein the energy storage device includes a battery.
14. The uninterruptible power supply of claim 13, wherein the resonant element includes an inductor.
15. The uninterruptible power supply of claim 14, wherein the transfer switch is constructed and arranged to receive the AC power from the input and to receive the AC power from the output of the inverter and to provide one of the AC power from the input and the AC power from the output of the inverter to the load.
16. The uninterruptible power supply of claim 12, wherein the resonant element includes an inductor.
17. The uninterruptible power supply of claim 12, wherein the transfer switch is constructed and arranged to receive the AC power from the input and to receive the AC power from the output of the inverter and to provide one of the AC power from the input and the AC power from the output of the inverter to the load.
18. A method of supplying an uninterruptible AC voltage to a load having a capacitive element using an uninterruptible power supply having a DC voltage source with an energy storage device, the method comprising steps of: charging the capacitive element by supplying electrical current from the DC voltage source to the load through a resonant element in the uninterruptible power supply; supplying load current from the DC voltage source to the load after the capacitive element has been charged to a predetermined voltage; discharging the capacitive element through the resonant element; and transferring energy from the resonant element to the energy storage device in the DC voltage source.
19. The method of claim 18, further comprising steps of: receiving an AC voltage from an AC power source; selecting one of the AC power source and the DC voltage source as an output power source for the uninterruptible power supply.
20. The method of claim 18, wherein the resonant element includes an inductor.
PCT/US2000/012921 1999-05-13 2000-05-11 Method and apparatus for converting a dc voltage to an ac voltage WO2000070736A1 (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
EP00930608A EP1186094B1 (en) 1999-05-13 2000-05-11 Method and apparatus for converting a dc voltage to an ac voltage
DE2000622346 DE60022346T2 (en) 1999-05-13 2000-05-11 METHOD AND DEVICE FOR CONVERTING AN EQUIVALENT VOLTAGE INTO AN ALTERNATING VOLTAGE
AT00930608T ATE303668T1 (en) 1999-05-13 2000-05-11 METHOD AND DEVICE FOR CONVERTING A DC VOLTAGE INTO AN AC VOLTAGE
JP2000619079A JP4651824B2 (en) 1999-05-13 2000-05-11 Method and apparatus for converting DC voltage to AC voltage
AU48400/00A AU770941B2 (en) 1999-05-13 2000-05-11 Method and apparatus for converting a DC voltage to an AC voltage
CA 2373762 CA2373762C (en) 1999-05-13 2000-05-11 Method and apparatus for converting a dc voltage to an ac voltage

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US09/311,043 US6404658B1 (en) 1999-05-13 1999-05-13 Method and apparatus for converting a DC voltage to an AC voltage
US09/311,043 1999-05-13

Publications (2)

Publication Number Publication Date
WO2000070736A1 true WO2000070736A1 (en) 2000-11-23
WO2000070736A9 WO2000070736A9 (en) 2002-04-18

Family

ID=23205147

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2000/012921 WO2000070736A1 (en) 1999-05-13 2000-05-11 Method and apparatus for converting a dc voltage to an ac voltage

Country Status (9)

Country Link
US (4) US6404658B1 (en)
EP (2) EP1186094B1 (en)
JP (1) JP4651824B2 (en)
AT (1) ATE303668T1 (en)
AU (1) AU770941B2 (en)
CA (1) CA2373762C (en)
DE (1) DE60022346T2 (en)
ES (1) ES2430370T3 (en)
WO (1) WO2000070736A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7755872B2 (en) 2006-09-14 2010-07-13 Schweitzer Engineering Laboratories, Inc. System, method and device to preserve protection communication active during a bypass operation

Families Citing this family (58)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6404658B1 (en) * 1999-05-13 2002-06-11 American Power Conversion Method and apparatus for converting a DC voltage to an AC voltage
DE10002583A1 (en) * 2000-01-21 2001-08-09 Piller Gmbh Device for the uninterruptible power supply of an electrical load with alternating current
US6593796B1 (en) * 2000-09-20 2003-07-15 Sipex Corporation Method and apparatus for powering multiple AC loads using overlapping H-bridge circuits
SE523486C2 (en) * 2001-07-16 2004-04-20 Abb Ab Converter and method of controlling a converter
JP3829846B2 (en) * 2001-10-03 2006-10-04 三菱電機株式会社 Uninterruptible power system
US6898094B2 (en) * 2001-11-19 2005-05-24 Kone Corporation DC/DC bridge control unit for controlling a direct-current load
US6787259B2 (en) * 2002-09-12 2004-09-07 Metallic Power, Inc. Secondary power source for use in a back-up power system
US7281540B2 (en) 2002-12-20 2007-10-16 R.J. Reynolds Tobacco Company Equipment and methods for manufacturing cigarettes
US7612472B2 (en) 2004-01-23 2009-11-03 American Power Conversion Corporation Method and apparatus for monitoring energy storage devices
US7446433B2 (en) * 2004-01-23 2008-11-04 American Power Conversion Corporation Methods and apparatus for providing uninterruptible power
US7379305B2 (en) 2004-01-23 2008-05-27 American Power Conversion Corporation Modular UPS
DE102004018502B3 (en) * 2004-04-14 2006-01-12 Phoenix Contact Gmbh & Co. Kg Device for uninterruptible power supply
US7274112B2 (en) * 2004-08-31 2007-09-25 American Power Conversion Corporation Method and apparatus for providing uninterruptible power
US7939968B2 (en) * 2004-08-31 2011-05-10 American Power Conversion Corporation Method and apparatus for providing uninterruptible power
US7456518B2 (en) 2004-08-31 2008-11-25 American Power Conversion Corporation Method and apparatus for providing uninterruptible power
US7737580B2 (en) * 2004-08-31 2010-06-15 American Power Conversion Corporation Method and apparatus for providing uninterruptible power
US7400493B2 (en) * 2004-11-01 2008-07-15 Server Technology, Inc. Circuit breaking link status detection and reporting circuit
US7151678B2 (en) * 2004-12-15 2006-12-19 Motorola, Inc. Power system with redundant power supply apparatus
CN101199108B (en) * 2005-01-28 2010-06-09 皇家飞利浦电子股份有限公司 Method and inverter for converting a DC voltage into a 3-phase AC output
US7274975B2 (en) * 2005-06-06 2007-09-25 Gridpoint, Inc. Optimized energy management system
US7511451B2 (en) * 2005-07-07 2009-03-31 Gerald Pierce Electrical energy source
CA2620828A1 (en) * 2005-09-19 2007-03-29 Schweitzer Engineering Laboratories, Inc. Method and apparatus for routing data streams among intelligent electronic devices
US8672732B2 (en) * 2006-01-19 2014-03-18 Schneider Electric It Corporation Cooling system and method
US8103389B2 (en) 2006-05-18 2012-01-24 Gridpoint, Inc. Modular energy control system
US8415928B2 (en) * 2006-06-30 2013-04-09 System General Corp. Power circuit
CN1908843B (en) * 2006-08-07 2015-05-20 崇贸科技股份有限公司 AC/DC power circuit
US7550873B2 (en) * 2007-01-28 2009-06-23 Ming Jiang Uninterruptible power supply for home/office networking and communication system
WO2008144375A2 (en) 2007-05-15 2008-11-27 American Power Conversion Corporation Methods and systems for managing facility power and cooling
US8116105B2 (en) * 2008-02-07 2012-02-14 American Power Conversion Corporation Systems and methods for uninterruptible power supply control
US7881079B2 (en) * 2008-03-24 2011-02-01 American Power Conversion Corporation UPS frequency converter and line conditioner
US8212402B2 (en) 2009-01-27 2012-07-03 American Power Conversion Corporation System and method for limiting losses in an uninterruptible power supply
US8040695B2 (en) * 2009-03-13 2011-10-18 American Power Conversion Corporation Method for portioning output current of a DC-DC converter
US8228046B2 (en) * 2009-06-16 2012-07-24 American Power Conversion Corporation Apparatus and method for operating an uninterruptible power supply
US8488350B2 (en) * 2009-09-25 2013-07-16 Astec International Limited DC-AC inverters
US8503201B2 (en) * 2009-12-03 2013-08-06 Schneider Electric It Corporation Transient clamping circuitry for voltage converter
US8698354B2 (en) 2010-11-05 2014-04-15 Schneider Electric It Corporation System and method for bidirectional DC-AC power conversion
US8853887B2 (en) 2010-11-12 2014-10-07 Schneider Electric It Corporation Static bypass switch with built in transfer switch capabilities
WO2012092606A2 (en) * 2010-12-30 2012-07-05 Innovolt, Inc. Line cord a ride-through functionality for momentary disturbances
US8878389B2 (en) 2011-01-11 2014-11-04 Schneider Electric It Corporation Method and apparatus for providing uninterruptible power
US8803361B2 (en) 2011-01-19 2014-08-12 Schneider Electric It Corporation Apparatus and method for providing uninterruptible power
CA2833384C (en) 2011-04-18 2019-08-20 Innovolt, Inc. Voltage sag corrector using a variable duty cycle boost converter
US8884464B2 (en) 2011-08-29 2014-11-11 Schneider Electric It Corporation Twin boost converter with integrated charger for UPS system
AU2011383606A1 (en) 2011-12-22 2014-07-17 Schneider Electric It Corporation System and method for prediction of temperature values in an electronics system
AU2011384046A1 (en) 2011-12-22 2014-07-17 Schneider Electric It Corporation Analysis of effect of transient events on temperature in a data center
FR2987954B1 (en) * 2012-03-07 2016-02-05 Valeo Equip Electr Moteur METHOD FOR CONTROLLING A POWER BRIDGE, STEERING DEVICE, POWER BRIDGE AND CORRESPONDING ROTATING ELECTRICAL MACHINE SYSTEM
US10459464B2 (en) 2012-09-03 2019-10-29 Schneider Electric It Corporation Method and apparatus for controlling distribution of power
CN103078395B (en) * 2013-01-07 2015-03-04 无锡必创传感科技有限公司 Power supply dynamic route managing circuit
WO2016028566A1 (en) 2014-08-20 2016-02-25 R. J. Reynolds Tobacco Company Seam-sealing adhesive application apparatus and associated method
US10345348B2 (en) * 2014-11-04 2019-07-09 Stmicroelectronics S.R.L. Detection circuit for an active discharge circuit of an X-capacitor, related active discharge circuit, integrated circuit and method
DE102015001890C5 (en) 2015-02-14 2021-11-25 HARTING Customised Solutions GmbH & Co. KG Emergency light
US9893604B2 (en) 2015-07-21 2018-02-13 Robert W. Horst Circuit with low DC bias storage capacitors for high density power conversion
US10211750B2 (en) 2016-02-12 2019-02-19 Schneider Electric It Corporation Apparatus and method for low frequency power inverter
TWI604678B (en) * 2016-09-07 2017-11-01 國立暨南國際大學 Radio transmission system
CN110249499A (en) * 2016-12-15 2019-09-17 万喻 Low emissivity uninterruptible power supply
GB201719104D0 (en) * 2017-11-17 2018-01-03 Hofmeir Magnetics Ltd Pulsed electromagnetic field therapy device
US11863062B2 (en) * 2018-04-27 2024-01-02 Raytheon Company Capacitor discharge circuit
US11011926B2 (en) * 2018-07-03 2021-05-18 Schneider Electric It Corporation Adaptive charger
US11777414B2 (en) 2021-07-02 2023-10-03 Schneider Electric It Corporation Interleaved power conversion systems and methods

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4717998A (en) * 1985-07-22 1988-01-05 Agence Nationale De Valorisation De La Recherche (A.N.V.A.R.) Static device for control of energy-exchange between electrical generating and/or receiving systems
EP0420628A2 (en) * 1989-09-29 1991-04-03 Wisconsin Alumni Research Foundation AC to DC to AC power conversion apparatus with few active switches and input and output control
EP0696831A2 (en) * 1994-08-10 1996-02-14 York Technologies, Inc Modular power supply system

Family Cites Families (47)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3466528A (en) * 1967-08-29 1969-09-09 Park Ohio Industries Inc Inverter for induction heating use
JPS5074738A (en) * 1973-11-07 1975-06-19
JPS5145227A (en) * 1974-10-16 1976-04-17 Hitachi Ltd
US4115704A (en) 1977-04-27 1978-09-19 The United States Of America As Represented By The Secretary Of The Navy Parametric energy coupled uninterruptible power supply
US4305033A (en) 1980-02-11 1981-12-08 Liebert Corporation Polyphase ferroresonant voltage stabilizer having input chokes with non-linear impedance characteristic
US4473756A (en) 1983-05-23 1984-09-25 Caloyeras, Inc. AC Uninterruptible power system
US4517470A (en) 1983-08-22 1985-05-14 Ncr Corporation High frequency inverter
US4827150A (en) 1988-06-08 1989-05-02 Reynal Thomas J Uninterruptible power supply inverter circuit
EP0358191B1 (en) * 1988-09-06 1995-04-05 Kabushiki Kaisha Toshiba PWM-controlled power supply capable of eliminating modulation-frequency signal components from ground potentials
US4939633A (en) 1989-02-03 1990-07-03 General Signal Corporation Inverter power supply system
US4916599A (en) 1989-03-29 1990-04-10 Hyperpower, Inc. Switching power supply
US5010469A (en) 1990-05-09 1991-04-23 Albar Uninterruptible power supply with dual level voltage input
US5251121A (en) 1990-05-23 1993-10-05 Ntc Technology, Inc. Power supplies
CA2056010C (en) * 1990-11-27 1997-05-27 Minoru Maehara Inverter device for stable, high power-factor input current supply
US5513088A (en) 1991-06-14 1996-04-30 Williamson; Floyd Uninterruptable off-line, isolated flyback topology switch-mode power supply
US5175155A (en) 1991-10-07 1992-12-29 Sterling Winthrop Inc. Win 49596-finasteride method of use and compositions
US5680301A (en) 1992-09-02 1997-10-21 Exide Electronics Corporation Series/parallel resonant converter
JP3366058B2 (en) 1992-10-07 2003-01-14 浩 坂本 Power supply
US5347164A (en) 1992-10-08 1994-09-13 Accton Technology Corporation Uninterruptible power supply having a 115V or 230V selectable AC output and power saving
JPH06245530A (en) 1993-02-23 1994-09-02 Matsushita Electric Works Ltd Power device
JP2996065B2 (en) * 1993-07-30 1999-12-27 サンケン電気株式会社 Bridge type inverter device
KR950019786A (en) 1993-12-21 1995-07-24 이헌조 Communication optical fiber
JPH07261701A (en) * 1994-03-20 1995-10-13 Fujitsu Ltd Capacitive load driving circuit and its driving method
JP3382012B2 (en) 1994-04-25 2003-03-04 松下電工株式会社 Self-excited inverter device
US5686797A (en) * 1994-05-24 1997-11-11 Bkl, Inc. Electronluminescent lamp inverter
US5625548A (en) * 1994-08-10 1997-04-29 American Superconductor Corporation Control circuit for cryogenically-cooled power electronics employed in power conversion systems
US5610805A (en) * 1995-01-10 1997-03-11 Cambridge Continuous Power Uninterruptible power supply with a back-up battery coupled across the a.c. input
US5602462A (en) 1995-02-21 1997-02-11 Best Power Technology, Incorporated Uninterruptible power system
CA2168520C (en) 1995-02-22 2003-04-08 Fereydoun Mekanik Inverter/charger circuit for uninterruptible power supplies
US5561595A (en) * 1995-03-24 1996-10-01 Magl Power Inc. Power inverter with input line conditioning
US5557175A (en) * 1995-06-13 1996-09-17 Harris Corporation Battery operated inverter circuit for capacitive loads such as electroluminescent lamps
US5525869A (en) * 1995-06-15 1996-06-11 Harris Corporation Efficient battery operated inverter circuit for capacitive loads such as electroluminescent lamps
JP3351192B2 (en) * 1995-07-12 2002-11-25 富士ゼロックス株式会社 Image reading signal processing device
US5635773A (en) 1995-08-23 1997-06-03 Litton Systems, Inc. High efficiency, no dropout uninterruptable power supply
US5646835A (en) 1995-11-20 1997-07-08 General Electric Company Series resonant converter
US5784270A (en) 1995-12-29 1998-07-21 Valeo Electronique Method of controlling an H-bridge
US5774351A (en) 1996-05-21 1998-06-30 National Science Council Series resonant DC-to-AC inverter system
US5781399A (en) 1996-08-05 1998-07-14 Lanigan; William P. Energy efficient control circuit for solenoid actuated locking device
US5734565A (en) 1996-08-16 1998-03-31 American Superconductor Corporation Reducing switching losses in series connected bridge inverters and amplifiers
JPH1084677A (en) * 1996-09-09 1998-03-31 Nippon Electric Ind Co Ltd Uninterruptible power supply provided with multifunction output
US5715155A (en) 1996-10-28 1998-02-03 Norax Canada Inc. Resonant switching power supply circuit
US6184662B1 (en) * 1997-12-25 2001-02-06 Mitsubishi Denki Kabushiki Kaisha Pulsed power supply device
US6404658B1 (en) * 1999-05-13 2002-06-11 American Power Conversion Method and apparatus for converting a DC voltage to an AC voltage
WO2000079674A1 (en) * 1999-06-22 2000-12-28 Tdk Corporation Switching power supply
US6278245B1 (en) * 2000-03-30 2001-08-21 Philips Electronics North America Corporation Buck-boost function type electronic ballast with bus capacitor current sensing
US6343021B1 (en) * 2000-05-09 2002-01-29 Floyd L. Williamson Universal input/output power supply with inherent near unity power factor
JP2002033651A (en) * 2000-07-17 2002-01-31 Mitsubishi Electric Corp Load capacitance measurement circuit and output buffer

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4717998A (en) * 1985-07-22 1988-01-05 Agence Nationale De Valorisation De La Recherche (A.N.V.A.R.) Static device for control of energy-exchange between electrical generating and/or receiving systems
EP0420628A2 (en) * 1989-09-29 1991-04-03 Wisconsin Alumni Research Foundation AC to DC to AC power conversion apparatus with few active switches and input and output control
EP0696831A2 (en) * 1994-08-10 1996-02-14 York Technologies, Inc Modular power supply system

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7755872B2 (en) 2006-09-14 2010-07-13 Schweitzer Engineering Laboratories, Inc. System, method and device to preserve protection communication active during a bypass operation

Also Published As

Publication number Publication date
AU4840000A (en) 2000-12-05
DE60022346D1 (en) 2005-10-06
EP1605577A2 (en) 2005-12-14
US6404658B1 (en) 2002-06-11
WO2000070736A9 (en) 2002-04-18
JP4651824B2 (en) 2011-03-16
AU770941B2 (en) 2004-03-11
CA2373762A1 (en) 2000-11-23
US20030026113A1 (en) 2003-02-06
US6630751B2 (en) 2003-10-07
EP1186094B1 (en) 2005-08-31
CA2373762C (en) 2008-04-08
US20010033505A1 (en) 2001-10-25
EP1605577B1 (en) 2013-07-17
US6400591B2 (en) 2002-06-04
DE60022346T2 (en) 2006-06-14
US20020030411A1 (en) 2002-03-14
ATE303668T1 (en) 2005-09-15
JP2004500791A (en) 2004-01-08
EP1186094A1 (en) 2002-03-13
US6728119B2 (en) 2004-04-27
ES2430370T3 (en) 2013-11-20
EP1605577A3 (en) 2009-06-24

Similar Documents

Publication Publication Date Title
CA2373762C (en) Method and apparatus for converting a dc voltage to an ac voltage
CN107251398B (en) DC-DC converter
US9024609B2 (en) Circuit and method for providing hold-up time in a DC-DC converter
CN100418293C (en) Capacitively coupled power supply
US11264894B2 (en) Converter and current control system thereof
JPH03107328A (en) Snubber circuit for power converter
EP0588635B1 (en) Gate power supply circuit
Biebach et al. Compact modular power supplies for superconducting inductive storage and for capacitor charging
US6519164B1 (en) Single power stage AC/DC forward converter with power switch voltage clamping function
CN108832710B (en) Charging and discharging balance converter for uninterrupted power supply
US10554119B1 (en) Inverter apparatus with overcurrent protection control
US20230253877A1 (en) Power factor correction and dc-dc multiplexing converter and uninterruptible power supply including the same
WO2020245260A1 (en) Arrangement for generating electrical pulses
JP2004537942A (en) Series power switch bridge with automatic voltage distribution
CN110957900A (en) Clamping circuit for reducing overshoot in power converter
CN214380727U (en) Motor power supply control device and system
CN112910371A (en) Motor power supply control device and system
CN116780476A (en) Control device of switch power supply
JP2893232B2 (en) Boost type uninterruptible power supply
JPH0970174A (en) High-frequency inverter
JP2000092709A (en) Active filter device

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY CA CH CN CR CU CZ DE DK DM DZ EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX NO NZ PL PT RO RU SD SE SG SI SK SL TJ TM TR TT TZ UA UG US UZ VN YU ZA ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GH GM KE LS MW SD SL SZ TZ UG ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE BF BJ CF CG CI CM GA GN GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
ENP Entry into the national phase

Ref country code: JP

Ref document number: 2000 619079

Kind code of ref document: A

Format of ref document f/p: F

ENP Entry into the national phase

Ref document number: 2373762

Country of ref document: CA

Ref country code: CA

Ref document number: 2373762

Kind code of ref document: A

Format of ref document f/p: F

WWE Wipo information: entry into national phase

Ref document number: 48400/00

Country of ref document: AU

WWE Wipo information: entry into national phase

Ref document number: 2000930608

Country of ref document: EP

WWP Wipo information: published in national office

Ref document number: 2000930608

Country of ref document: EP

REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

AK Designated states

Kind code of ref document: C2

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY CA CH CN CR CU CZ DE DK DM DZ EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX NO NZ PL PT RO RU SD SE SG SI SK SL TJ TM TR TT TZ UA UG US UZ VN YU ZA ZW

AL Designated countries for regional patents

Kind code of ref document: C2

Designated state(s): GH GM KE LS MW SD SL SZ TZ UG ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE BF BJ CF CG CI CM GA GN GW ML MR NE SN TD TG

COP Corrected version of pamphlet

Free format text: PAGES 1/10-10/10, DRAWINGS, REPLACED BY NEW PAGES 1/10-10/10; DUE TO LATE TRANSMITTAL BY THE RECEIVING OFFICE

WWG Wipo information: grant in national office

Ref document number: 48400/00

Country of ref document: AU

WWG Wipo information: grant in national office

Ref document number: 2000930608

Country of ref document: EP