CA2543461A1 - System and methods for charging batteries - Google Patents

Abstract

A high frequency battery charger includes a converter, drive logic, and control logic. The converter transforms a DC voltage into a high frequency AC
voltage. The drive logic controls a conversion of the high frequency AC
voltage through a train of pulses. The control logic adjusts the output of the converter to maximize a charging cycle of a battery. The method of transforming an AC input into a direct current output used to charge a rechargeable battery includes transforming an AC input into a first DC output;
transforming the first DC output into a high frequency AC output; transforming the high frequency AC output into a second DC output; and passing a charging current to an external load when the load is correctly connected to an output.

Description

SYSTEM AND METHOD FOR CHARGING BATTERIES
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional Application No.
601514,407 associated with attorney docket number 12188 / 6, filed October 23, 2003, the disclosure of which is incorporated herein by reference.
FIELD OF THE INVENTION
(0002] This invention relates to a system and a method that charges a battery, and more particularly, to a system and method that charges and monitors a rechargeable battery.
BACKGROUND

[0003] A battery can deliver can -ent to a load such as an engine, a light, or a radio for a considerable length of time. As long as the potential difference between its terminals remains close to a nominal value and a sufficient current is generated, current will flow to the load. As the current flows, the battery's capacity to drive the load becomes diminished and may eventually become exhausted.

[0004] To replenish this loss, a battery may be connected to a source that provides both positive and negative charges to its electrodes. It is these charges that establish the potential difference and the current needed to drive the load. The charges are transported from one terminal to the other in a direction that is opposite to the bias of the terminals. One device that accomplishes this transport is an automobile battery charger.

[0005] A known automobile battery charger converts 120-volts, 60-Hz AC-line, to a 12-volt DC output through a power transformer, a bridge rectifier-, and a filter.
The power transformer consists of two separate windings that are magnetically coupled to each other.
The first winding is connected to the 120-volt AC-line, and the second winding is connected to the bridge rectifier. Through a selection of an appropriate turn ratio, the AC-line voltage is stepped down to a 12-volts AC-line output. The bridge rectifier convents this stepped down AC-line output to a rectified output that is not always suitable for charging batteries.

By eliminating the time varying magnitudes of the rectified output through a filter, the output of the battery charger is stabilized and is suitable for charging a battery.

[0006) Conceptually, the described battery charger is relatively simple and can be made inexpensively. The large size of the power transformer needed in many battery chargers can make the battery chargers very heavy. Other battery chargers may not provide a reliable charge or a reliable charge termination. Overcharging a battery can reduce a battery's life and lead to the emission of dangerous cowosives. If battery terminals are insulated by sulfates, some battery chargers will not deliver sufficient current to charge the battery. In this condition, the battery becomes an open circuit.
SUMMARY

[0007] The present invention is defined by the following claims. This description summarizes some aspects of the present embodiments and should not be used to limit the claims.

[0008] A high frequency battery charger comprises a converter, drive logic, and control logic. The converter transforms a DC voltage into a high frequency AC voltage.
The drive logic controls a conversion of the high frequency AC voltage by producing a train of pulses.
The control logic. adjusts the output of the converter to maximize a charging cycle of a battery.

(0009] A method of transforming an AC input into a direct current output used to charge a rechargeable battery comprises transforming an AC-line input into a first DC
output;
transforming the first DC output into a high frequency AC output; transforming the high frequency AC output into a second DC output; and passing a charging current to a load when the load is correctly connected to an output of a charging connector.

[0010) Further aspects and advantages of the invention are described below in conjunction with the present embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a block diagram of an exemplary high frequency battery charger coupled to a battery.

[0012] Figure 2 is a block diagram of a second exemplary high frequency battery charger coupled to a battery.

[0013] Figure 3 is a block diagram of a third exemplary high frequency battery charger.

[0014] Figure 4 is a schematic of an exemplary converter of Figure 3.

[0015] Figure 5 is a schematic of an exemplary first sensor and drive logic of Figure 3.

(0016] Figure 6 is a schematic of an exemplary synchronous converter of Figure 3.

[0017] Figure 7 is a schematic of an exemplary output of Figure 3.

[0018] Figure 8 is a schematic of an exemplary regulator of Figure 3.

(0019) Figure 9 is a partial schematic of an exemplary second sensor of Figure 3.

[0020] Figure 10 is a second partial_schematic of an exemplary second sensor and a delay of Figure 3 coupled to a processor.

[0021) Figure 11 is schematic of an exemplary isolator of Figure 3.

(0022] Figure 12 is a schematic of an exemplary display driver and visual output of Figure 3.

[0023] Figure 13 is a partial exemplary flow diagram of the states of an exemplary high frequency battery charger.

[0024] Figure 14 is a pauial exemplary flow diagram of the states of an exemplary high frequency battery charger.

[0025) Figure 15 is a partial exemplary flow diagram of the states of an exemplary high frequency battery charger.
[002G] Figure 16 is an exemplary state diagram of an exemplary high frequency battery charger.
[0027] Figure 17 illustrates a second exemplary synchronous converter of figure 3.
[0028] Figure 18 illustrates a third exemplary synchronous converter of figure 3.
[0029) Figure 19 illustrates a second exemplary output of figure 3.

(0030] Figure 20 illustrates a partial second exemplary drive circuit of figure 3.
DETAILED DESCRIPTION OF THE PRESENT EMBODIMENTS
[0031] The present system and method provide a highly efficient charging technology that maintains the charging levels of a battery within a desired range. The system and method may provide high frequency mufti-stage charging to ensure that a battery reaches and sustains its full charge level. Depending on the battery type or a user's selection, a charging cycle of the system and method may be automatically terminated based on a monitoring of a battery voltage, a voltage change versus time, a temperature change versus time, a temperature change, a threshold current draw at a full charging voltage, a charge time, or any other metric or combination of.metrics.
[0032] In some systems and methods, a sensor prevents the charging technology from over charging a battery or passing a charging current when a battery's terminals are hooked up in a reverse polarity or are shorted together. The charging technology may provide spark ,, resistance even when the battery terminals are hooked up incourectly. In some systems and methods, the charging technology provides a pulse charge that may break up contaminants, chemicals, or sulfate layers that may build up on a battery's electrodes.
[0033] Figure 1 illustrates an exemplary high frequency battery charger 100.
In this illustration, a battery voltage is continuously or periodically monitored and a charging current continuously or periodically sensed by an electric sensor 102. A
current source 106 sources a charging current that charges and replenishes the battery 110 under the control of control logic 104. A temperature sensor 108 monitors battery 110 temperature and/or circuit temperatures.
[0034) In the exemplary high frequency battery charger 100, a charging voltage or current may be adjusted to maximize a battery's 110 charge level. The exemplary high frequency battery charger 100 may provide a bulls charge in which a maximum safe amperage is sourced to the battery 110. In a bulls mode, the. exemplary high frequency battery charger 100 may increase its charging voltage until the battery voltage reaches a predetermined or nearly a fully charged level. When the battery voltage reaches a desired level, the current source I06 may source an absorption or acceptance charge that maintains a relatively high fixed voltage until the charging current tapers off to a predetermined threshold. A float or trickle charge reduces the constant cuurent applied to the battery 110 to provide maintenance without boiling off electrolyte. An equalization charge provides a continuous high voltage or a series of fast rising pulse charges that may equalize the balance between battery cells. An equalization charge may reverse the build up of some contaminants such as sulfides that may build up on a battery's electrodes.
[0035] Because one of the most difficult parts of the charging process may be to correctly determine the termination of a charge, the exemplary high frequency battery charger 100 may use one or more systems or methods to terminate a charging cycle or sustain an equalization charge. Depending on an automatic or manual selection, the battery charge may automatically terminate a charging cycle based on the monitoring of a battery voltage, a voltage change versus time, a temperature change versus time, a temperature change, a threshold current draw at a predetermined or full charging voltage, a charge time, or any other metric or combination of metrics. Por example, a termination may occur when a battery reaches a desired threshold voltage or an absolute temperature, when the battery voltage reaches a peak or falls within a voltage range after reaching that peak, when a battery's temperature changes with respect to time exceeds a programmable tlu-eshold or when time lapses. In addition, a secondary termination process may also be used to back-up the primary termination process. The secondary temnination may comprise any metric or combination of metrics including those described above.
(003G] rigure 2 illustrates a second exemplary high frequency battery charger 200. The second exemplary high frequency battery charger 200 provides a programmable current control l OG, one or more switches 210, an interface 204, a display 20G, and a meter 208.
The switches 210 may be used to activate the exemplary high frequency battery charger 200 or select a charge mode, such as a bulk charge, an absorption charge, a float charge, an equalization charge, or a start charge that is capable of delivering a sufficient charging current to start a vehicle. When coupled to a communication application, the switches 210 may include an electronic or electromechanical device that controls the routing of signals through a parallel or a serial bus 212. In this exemplary high frequency battery charger 200, the bus 212 allows for the transfer of data between devices. One or more s~~itches 210 may also control diagnostics, a selection of a display mode, a selection of predetermined charging cun-ents (e.g., a two amp, ten amp, or another amperage) and/or a selection of a battery type.
[0037] A computer readable medium such as software may provide access to the controller 104 and its memory allowing a user or a device to receive or transfer information from a remote location. The interface 204 may allow a user or a remote or local device to request a service, initiate a diagnostic, program a charging interval or cycle, receive information relating to the battery or to the charging process, or process a request to display results. The meter 208 shown interconnected to the bus 212 preferably indicates and/or stores a characteristic of the battery or the charging process in a memory coupled to or resident to the controller 104. The controller 104 may record the current flowing through the battery 110 overtime, the charging voltage, the battery's 110 temperature, the ambient temperature, or any other recordable characteristic. This information may be exchanged or shared with any device that may interface the bus 212, including a vehicle interface or a communication link or a printer.
[0038] Because the programmable current control 106, electric sensor 102, and control logic 104 (e.g., the control circuits) of figure 2 are stable and predictable in time and temperature, the temperature sensor 108 shown in figure 2 may measure the temperature of the battery 110, an ambient temperature, and/or a temperature of the control cwcults.
Temperature parameters may be used to adjust the operation of the exemplary high frequency battery charger 200, including a selection of a charging curl-ent or a voltage level to maintain circuit stability andlor maximize a battery's 110 charge level.
[0039] Figure 3 illustrates a third exemplary high frequency battery charger 300. The third exemplary high frequency battery charger 300 converts electric power from an alternating current (AC) source 302 to a direct current (DC). A converter 304 transforms a uniform periodic input that varies in time into a block-like waveform that changes in time between a positive going state and a negative going state. Drive logic 310 controls the state of the block-like waveform. A high output from the drive logic 310 generates a positive going pulse; a pulse that is then stepped down by a transformer that links the output of the converter 304 to the synchronous converter 306.
[0040] A first current sensor 308 interconnected to the source 302 and the drive logic 310 senses high current conditions. When a high threshold current level is exceeded, the drive logic shuts down and the charging stops.
[0041] During normal operation, a transformer steps down the high frequency block-like waveform to a predefined amplitude. Using a pair of switches, the synchronous converter 306 transforms the block-like waveform into a desired DC voltage and charging current level.
[0042] A second sensor 326 senses the desired DC voltage or current flow at the output 312. A measurement of the voltage or current at the output connector 316 allows the control logic 328 to monitor and control the charging process and ensure that the battery is not under or over charged.
[0043] If a defective battery is connected to the output connector 316, the control logic may 328 detect the defective battery by monitoring the output at the battery connector 316 through the second sensor 326. If a defective battery is detected, some exemplary high frequency battery chargers disable output current flow to minimize the risk of injury. Other exemplary high frequency battery chargers select a modified float or trickle charge that passes only a safe charging current for a predetermined period of time. If a low battery voltage persists, the battery is/maybe considered defective, and the charge cycle is/may be terminated. In some exemplary high frequency battery chargers, the control logic 328 may issue an audio or visual warning when a defective battery is detected.
[0044] A spark resistant protection from a reverse hook-up or shorted output is provided through a third sensor 338. When battery-charging terminals are hooked-up in a reverse polarity or are shorted together, the third sensor 328 senses the condition and notifies the control logic 328. Once notified, the control logic 328 may shutoff the output 312, which resists or prevents sparking.
[0045] The exemplary high frequency battery charger 300 may not pass a charging current until the output of a regulator 314 exceeds a voltage threshold and the control logic 328 senses a correct polarity and a threshold battery voltage. When these conditions are met, a soft start delay may be initiated through the delay logic 330. Once the delay lapses, a signal from the isolator 332 may initiate the charging process by waking up the drive logic 310.
[0046] An interface 334 provides a point of connection between the control logic and any other entity, any other device such as a remote or local computer or a remote or local terminal or a vehicle control module or computer, or a remote user. A visual output 336 provides data or information in a visual form. An outlet 338 provides an ancillary source of power to one or more external loads.
[0047] Figure 4 illustrates an exemplary converter. The exemplary converter 404 uses a two-stage power conversion topology to scales the 120 V (rms) 60-Hz AC-line into a higher voltage square wave. The AC-line is fed through a fuse, transient suppressor, and LC line filters. The transient suppressor reduces voltage spikes. The LC line filters dampen interference.
[0048] A full wave diode rectifier converts the input AC-line voltage into a rectified output. Variations in the rectified output are reduced by a capacitor C1. The DC voltage across capacitor C 1 is transformed into a high frequency square wave. The high frequency square wave is generated and scaled by the drive logic 410 that completes current paths to selected primary windings of a first transformer Tl.
[0049] As shown in figure 5, a pair of switches Q 1 and Q2 connected to nodes B and C, respectively, provides current paths under the control of a pulse width modulator U 1. The pulse width modulator varies the duration of a train of pulses that control switches Q1 and Q2.

(0050] As shown in figures 5 and 6, a high cuu-ent sensor comprised of a second transformer T2, a pair of switches QS and Q6, and the pulse width modulator UI
shuts off switches Q I and Q2 when a high current condition is sensed. Through a selection of an appropriate turn ratio (Nl/N2), the rectified voltage is electrically isolated from the pulse width modulator UI and stepped dov<m to bias switch Q6. When a sufficient bias is reached, switches QS and Q6 are turned on pulling a dead time control (DTC) input of the pulse width modulator U 1 high. This shuts down the output of the exemplary high frequency battery charger 300.
(0051] During a normal charging operation, the first transformer T1 steps down the high frequency square wave to a selected amplitude. The first transformer T1 bridging figures 4 and 6 provide electrical isolation between the high voltage circuits shown in figures 4 and 5 and the low voltage circuits shown in figures 5 - 12.
(0052] A pair of switches Q I O l and Q 102 shown in figure 6 transforms the stepped down square .wave into a desired charging current and DC voltage level. A line filter L101 cormected to node G dampens line interference. A tap, node P, supplies power to a five-volt regulator U3 (figure 8) that supplies power to digital circuitry and other external loads when needed.
[0053] If a battery or load is correctly connected to the exemplary high frequency battery charger 300, charging current will flow through switches Q103 and Q104 shown in figure 7 to the battery or the load. A second sensor, that may be comprised of a processor, senses the output voltage of the battery or current flow into the battery at the battery terminals Bat +
and Bat -. The processor, which may include an on-chip analog-to-digital conveuter, monitors and controls the charging current and voltage to ensure that the battery is not under or over charged. In some exemplary battery chargers, the processor comprises a microprocessor or a signal processor, in other exemplary battery chargers, the processor comprises a device that controls high-speed data manipulations.
(0054] If a vehicle's alternator is charging a battery, the processor may disable current flow tlwough switches Q 103 and Q I 04 and monitor the charging voltage and/or current generated by the alternator. If a low cun-ent or a low voltage condition is detected, the processor may issue an audio or visual warning that may be stored in a memory.
The memory may be coupled to the processor or coupled to a controller resident to a vehicle.
(0055] If a defective battery is connected to the exemplary high frequency battery charger 300, the processor may monitor the charging cycle at the battery connectors Bat +
and Bat -. Differential amplifier U4A shown in figure 10 compares a scaled charging r~
voltage sourced through node H to a scaled battery voltage sourced through node J. If the scaled charging voltage exceeds the scaled battery voltage, a potentially defective battery may be detected. Some exemplary high frequency battery chargers disable output cun~ent flow when a defective battery is detected to minimize the risk of injuring a user. Other exemplary high frequency battery chargers select a modified float or trickle charge mode that passes only a safe charging cun-ent for a predetermined period of time.
If a low voltage persists at the battery connector Bat + and Bat -, the load may be considered defective, and the processor may terminate the charging cycle.
[0056] A termination signal may be generated when a low or a high voltage load is detected, cables are connected in a reverse polarity, upon completion of a charging cycle, upon a user's command, and under many other conditions. A charging cycle terminates when an active low termination signal is received at node M. The termination signal turns off switches Q I O5, Q 107, Q 103, and Q I 04, which disable the charging voltage and current.
[0057] A pair of switches Q 106 and Q 109 shown in figure 9 and the processor shown in figure 10 provides spark resistant protection from a reverse polarity connection. When the battery terminals are hooked-up in reverse polarity, a negative bias turns switch Q106 off and a positive bias turns switch Q 109 on. The negative battery sense is pulled high by its direct connection to the negative battery terminal. When the negative battery sense is pulled high, a termination signal turns on switch Q 105 and turns off switches Q 103 and Q 104 of figure 7 shutting down the exemplary high frequency battery charger 300.
Similarly, a short circuit at the battery connector Bat + and Bat - disables the charging cuurent and prevents sparking.

[0058] The exemplary high frequency battery charger 300 may not pass a charging current until the output of a regulator 314 exceeds a low voltage threshold and the processor senses a correct polarity and a threshold battery voltage. When these conditions are met, a signal from an opto-isolator U2 shown in figure 11 initiates the charging process by providing a reference voltage to the pulse width modulator Ul shown in figure 5. The reference voltage may control and regulate the pulse width modulator U1, including the duration of the pulse width and frequency of the output that drive switches Q
1 and Q2. A
visual display illustrated by the drivers Ul - U4 and light emitting diodes Dl - D15 shown in figure 12 transform data or information from the exemplary battery charger into a visual format. The display may show images, graphics, icons, menus, and dialog boxes that can be selected by a user's touch or a relative or absolute pointing device at a local or remote location.
(0059] As shown in figures 13 - 16, an exemplary battery charging method is illustrated through a seguence that may be translated into a computer readable or a storable medium such as a memory, programmed within a device such as one or more integrated circuits, or processed by a controller, a computer, a server, or a server cluster. If the method is performed by code or software, the code or software may reside in a memory resident to or interfaced to the control logic 328 of figure 3, a communication interface, or any other type of non-volatile or volatile memory interfaced or resident to the high frequency battery charger. The memory may include an ordered listing of executable instructions for implementing logical functions. A logical function may be implemented through digital circuitry, through source code, or through analog circuitry. The code or software may be embodied in any computer-readable or signal-bearing medium, for use by, or in connection with an instruction executable system, apparatus, or device. Such a system may include a computer-based system, a processor-containing system, or another system that may selectively fetch instructions from an instruction executable system, apparatus, or device that may also execute instructions.

[0060) A "computer-readable medium," "machine-readable medium," "propagated-signal" medium, and/or "signal-bearing medium" may comprise any means that contains, stores, communicates, propagates, or transports code or software for use by or in connection with an instruction executable system, apparatus, or device. The machine-readable medium may selectively be, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or propagation medium. A
non-exhaustive list of examples of a machine-readable medium would include: an electrical connection having one or more wires, a portable magnetic or optical disk, a volatile memory such as a Random Access Memory "RAM," a Read-Only Memory "ROM," an Erasable Programmable Read-Only Memory (EPROM or Flash memory), or an optical fiber (optical). A machine-readable medium may also include a tangible medium upon which code or software is printed, as the code or software may be translated into a high-level language that may be compiled through a scanner, and/or interpreted or otherwise processed. The processed medium may then be stored in a computer and/or machine memory.
(0061] The computer readable medium may program a device to perform mufti-stage charging, spark resistance, break-up contaminants or chemicals that build up on electrodes, perform diagnostics, and perform fault detection. Like the exemplary high frequency battery chargers described above, the present battery charging method may be used on a deep-cycle, lead-acid, calcium lead, and automotive or marine batteries including a gel electrolyte battery.
[0062] At act 1302 the exemplary battery charging method commences by detecting the state of a switch. In the exemplary battery charging method, a switch is a control device or an automated system used to control the execution of the exemplary battery charging method. In figures 13 - 16, the switches control diagnostics (switch 0), a selection of a display mode (switch 1), a selection of charging current (e.g., a two amp, ten amp, or an engine start condition; switch 2), and an identification of a battery type (switch 3).

(0063] At act 1304, test diagnostics commence. Test automation software resident to a memory within or coupled to a control logic performs various hardware and software tests.
If a problem is found, the software may alert the user through an audio or visual warning, often accompanied by a diagnostic message.
[0064] At act 1308, the exemplary method determines if a timer generated an interrupt. If an interrupt was received, the exemplary method suspends its current operations and transfers control to an interrupt handler that directs the exemplary method to act 1310.
(0065) At act 1310, a system that generates a continuous train of pulses is reset, before returning to act 1306.
[0066) At act 1312 the exemplary method determines if an inten~upt that bypasses and takes priority over interrupt requests generated by software and other such devices was generated. If a nonmaslcable interrupt is generated, the exemplary method suspends its current operations and transfers controller to an interrupt handler that directs the exemplary method to act I 314.
(0067] At act 1314 and 1316, the exemplary method measures and writes a battery voltage to a memory and resets a charging time.
[0068) At act 1318, an autopolling process determines the status of a first switch. If a first switch is actuated, a user may customize a display or an interface to their personal or desired specification at act 1320.
[0069] At act 1322, an autopolling process determines the status of a second switch. If a second switch is actuated, a user may select a maximum charge rate or program a charge sequence that may include a bulls charge, an absorption charge, a float charge, an equalization charge, or a start charge mode at act 1324. At act 1326, the exemplary method sets a state variable to 0.
[0070] At act I 328, an autopolling process determines the status of a third switch. If a third sv~itch is actuated, a user may identify a battery type. At act 1332, the exemplary method sets a state variable to 0.

[0071] At act 1334, the exemplary method determines if a battery voltage exceeds a predetermined tlu-eshold. In this exemplary method, if the battery voltage is less than about one volt, the exemplary method returns to act 1306.
[0072] At act 1336, the exemplary method determines if a state has been set.
If a state has been set, the exemplary method determines the status of the battery at act 1402.
[0073] At act 1402, the exemplary method determines if a battery voltage lies within a predetermined tl-u-eshold. In this exemplary method, the processor determines if a battery's voltage is greater than about one volt but less than about seventeen volts. If the battery voltage lies within that threshold, the exemplary method disables the charging current at act 1404, clears the state variable at act 1406, and the exemplary method returns to act 1306.
[0074] At act 1408, the exemplary method determines if the state variable has been set to 0. If the state variable has been set to 0, the exemplary method determines if an engine coupled to the battery has been started at act 1410. If the engine has been started, at act 1412 the exemplary method sets the state variable to 16 at act 1412 and the exemplary method returns to act 1306. If the engine has not been started, the exemplary method sets charge rate variables at act 1414, sets the state variable to 1 at act 1416, and returns to act 1306.
[0075] At act 1418, the exemplary method determines if the state variable has been set to 1. If the state variable has been set to l, the exemplary method initializes the ramp charging values at act 1420, sets the state variable to 2 at act 1422, and returns to act 1306.
[0076] At act,1424, the exemplary method determines if the state variable has been set to 2. If the state variable has been set to a 2, the exemplary method passes a charging current to the battery at act 1426, sets the state variable to 3 at act 1428, and returns to act 1306.
[0077] At act 1430, the exemplary method determines if the state variable has been set to 3. If the state variable has been set to 3, the exemplary method determines if the battery voltage has exceeded a predetermined threshold. At act 1432, the predetermined threshold is about nine volts.

[0078] If the predetermined threshold has been exceeded, at act 1434 the exemplary method sets the state variable to 4 and the exemplary method returns to act 1306. If the predetermined threshold has not been exceeded, the exemplary method determines if a charging time has exceeded a predetermined charging interval at act 1436.
[0079] At act 1436, the predetermined timing interval is about five minutes.
If the predetermined charging interval has been exceeded, the exemplary method sets the state variable to 8 at act 1438 and returns to act 1306. If the predetermined charging interval has not been exceeded, the exemplary method returns to act 1306.
[0080) At act 1440, the exemplary method determines if the state variable has been set to 4. If the state variable has been set to 4, the exemplary method determines if the battery voltage has exceeded a predetermined threshold. At act 1442, the predetermined threshold is about twelve volts.
(0081] If the predetermined tlueshold has been exceeded, at act 1444 the exemplary method sets the state variable to 5 and the exemplary method returns to act 1306. If the predetermined threshold has not been exceeded, the exemplary method determines if the time has exceeded a predetermined charging interval at act 1436.
[0082] At act 1436, the predetermined timing interval is about four hours. If the predetermined charging interval has been exceeded, the exemplary method sets the state variable to 8 at act 1448 and returns to act 1306. If the predetermined charging interval has not been exceeded, the exemplary method returns to act 1306.
[0083] At act 1502, the exemplary method determines if the state variable has been set to 5. If the state variable has been set to 5, the exemplary method determines if a charging time has exceeded a predeteumined charging interval at act 1504.
[0084] At act 1504, the predetermined timing interval is about five minutes.
If the predetermined charging interval has been exceeded, the exemplary method determines if the initial charging voltage has exceeded a predetermined threshold at act 1506.
At act 1506 the predetermined threshold is about 12.2 volts.

[0085] At act 1508, the exemplary method determines if the battery voltage has exceeded a predetermined threshold. At act 1508 the predetermined threshold is about 14.2 volts. If the battery voltage has exceeded about 14.2 volts, the state variable is set to 9 and the exemplary method returns to act 1306. If the battery voltage has not exceeded about 14.2 volts at act 1508, the exemplary method returns to act 1306.
[0086) If the charging time has not exceed five minutes at act 1504 or the initial charging voltage has not exceed about 12.2 volts at act 1512, the exemplary method determines if the charging voltage exceeds a predetermined threshold at act 1512. At act 1512, the predetermined threshold is about 14.2 volts. If the battery voltage has exceeded about 14.2 volts, the state variable is set to 14 and the exemplary method returns to act 1306. If the battery voltage has not exceeded about 14.2 volts, the state variable is set to 11 and the exemplary method returns to act 1306.
[0087) At act 1518, the exemplary method determines if the state variable has been set to 8. If the state variable has been set to 8, the exemplary method aborts the charging method at act 1520, displays a message at act 1520, clears the state variable at act 1524, and returns to act 1306.
[0088] At act 1526 the exemplary method determines if the state variable has been set to 9. If the state variable has been set to 9, the exemplary method initiates a desulfating method at act 1528.
[0089] At act 1528 the exemplary method determines if a charging time exceeded a predetermined charging interval. At act 1528 the predetermined timing interval is about five minutes.
[0090] If the predetermined charging interval has been exceeded, the exemplary method determines if the battery voltage has exceeded a predetermined threshold. At act 1532 the predetermined threshold is about 14.2 volts. If the battery voltage has exceeded about 14.2 volts, the state variable is set to 0 and the exemplary method returns to act 1306. If the battery voltage has not exceeded about 14.2 volts at act 1532 the exemplary method determines if a charging time exceeded a predetermined charging interval. At act 1536 the predetermined timing interval is about ten hours.
[0091) If the charging time exceeds about ten hours at act 1536, the state variable is set to 8 at act 1538 and the exemplary method returns to act 1306. If the charging time did not exceed about ten hours at act 1536, the exemplary method returns to act 1306.
[0092) At act 1540 the exemplary method determines if the state variable has been set to 11. If the state variable has been set to 11, the exemplary method monitors a rate of change of the battery's voltage over time at act 1542.
[0093) At act 1544 the exemplary method determines if a charging time exceeds a maximum charging interval. If the predetermined charging interval has exceeded a maximum threshold at act 1554, the exemplary method sets the state variable to 8 and returns to act 1306.
(0094) At act 1548, the exemplary method determines if the battery voltage exceeds a maximum threshold. If the battery voltage does not exceed a maximum threshold, the exemplary method sets the state variable to 12, and the exemplary method returns to act 1306. If the battery voltage exceeds a maximum threshold, the exemplary method determines if the battery maintains a constant voltage at act 1550. If the battery maintains a constant voltage at act 1550, the exemplary method returns to act 1306. If the battery does not maintain a constant voltage, the state variable is set to 12, and the exemplary method returns to act 1306.
[0095] At act 1554 the exemplary method determines if the state variable has been set to 12. If the state variable has been set to 12, the exemplary method monitors the rate of change of the battery's current over time at act 1556.
[0096) At act 1558 the exemplary method determines if the battery can drive a constant current or a minimum current. If the battery can drive a constant or a minimum current at act 1558, the exemplary method sets the state variable to 13 at act 1546 and returns to act 1306.

[0097) At act 1562 the exemplary method determines if a maximum charging time has exceeded a predefined maximum charging time. If the maximum charging time has lapsed and the exemplary method has not previously executed this branch instruction, the exemplary method reduces the charging voltage and increases the predefined maximum charging time by a predetermined time period at act 1564 and 1562. If the exemplary method previously executed the branch instruction at act 1564, the exemplary method sets the state variable to 13 and returns to act 1306.
[0098] If a maximum charging time has not exceeded a predefined maximum charging time at act 1562, the exemplary method returns to act 1306.
[0099] At act 1566 the exemplary method determines if the state variable has been set to 13. If the state variable has been set to 13, the exemplary method initiates an end of charge method at act 1568.
[00100] At act 1570 the exemplary method determines if a charging time exceeded a predetermined charging interval called an end of charge time. If the charging time has exceeded the end of charge time, the exemplary method set the state variable to 14 at act 1572 and returns to act 1306. If the charging time has not exceeded the end of charge time at act 1570, the exemplary method returns to act 1306.
[00101] At act 1574 the exemplary method determines if the state variable has been set to 14. If the state variable has been set to 14, the exemplary method maintains its charging state at act 1576 and returns to act 1306.
[00102] At act 1578 the exemplary method determines if the state variable has been set to 16. If the state variable has been set to 16, the exemplary method initializes an engine start routine at act 1580. At act 1582, the exemplary method initializes a charge. At act 1584, the exemplary method initializes the charge. At act 1584, the exemplary method delivers a high cun-ent output sufficient to start a vehicle. At act 1586, the exemplary method sets the state variable to 17 and returns to act 1306.
[00103] At act 1590 the exemplay method determines if the state variable has been set to 17. If the state variable has been set to 17, the exemplary method determines if the charging tune has exceeded a predetermined charging interval at act 1592. At act 1592, the predetermined charging interval is about fifteen minutes. If the predetermined charging interval has exceeded about fifteen minutes, the exemplary method discontinues charging at act 1594, sets the state variable to 0 and returns to act 1306.
[00104] If the predetermined charging interval has not exceeded about fifteen minutes, the exemplary method determines if the battery drops a predetermined threshold when charging stops at act 1598. At act 1598 the threshold is about one volt. If the battery drops about one volt, the exemplary method sets the state variable to 19 and returns to act 1306. If the battery voltage does not drop about 1 volt, the exemplary method returns to act 1306.
[00105] At act 1602 the exemplary method determines if the state variable has been set to 19. If the state variable has been set to 19, the exemplary method determines if the charging time has exceeded a predetermined charging interval at act 1604. At act 1604, the predetermined charging interval is about eight seconds. If the predetermined charging interval is less than about eight seconds, the exemplary method sets the positive going state of a charging pulse to about eight seconds and then returns to act 1306. If the predetermined charging interval is less than about eight seconds, the exemplary method sets the state variable to 20 and returns to act 1306.
[00106] At act 1610 the exemplary method determines if the state variable has been set to 20. If the state variable has been set to 20, the exemplary method determines if the charging time has exceeded a predetermined charging interval at act 1612. At act 1612, the predetermined charging interval is about two hundred and Forty seconds. If the predetermined charging interval is less than about two hundred and forty seconds, the exemplary method sets the positive going state of a charging pulse to about two hundred and forty seconds and then returns to act 1306. If the predetermined charging interval is less than about two hundred and forty seconds, the exemplary method sets the state variable to 16 and returns to act 1306.
[00107] Figure 17 illustrates a second exemplary synchronous conveuter that may be used with the exemplary systems and methods described above. In this alternative, Q 101 and Q102 are connected across the secondary of transformer Tl and are referenced to ground. When a control signals are supplied to the secondary, such as when the gate of Q 101 is high and the gate of Q 102 is low, current flows through 8102, 8104, and 8106 turning Q 104 on, while Q 102 is turned off. With Q 1 O 1 turned on, current flows through Q101, L101, the center tap, and L101 to node G. Similarly, when the gate of Q102 is driven high, the gate of Q 101 is driven low and current flows through Q 102, L 103, the center tap, and L101 to node G. Lilce the above-described embodiments, node P supplies power to a five-volt regulator U3 (figure 8) that may supply power to digital circuitry and other external loads when needed.
(0010] Figure 18 illustrates a third exemplary synchronous converter that may be used with the exemplary systems and methods described above. In this exemplary alternative, the synchronous converter may sense when the AC source is disconnected from the high frequency battery charger.
[00109] As shown, node X monitors the AC line through an optical isolation.
When an AC source is present Q17 and Q18 are biased on allowing the synchronous rectifier tr ansistors Q 12 - Q 15 to rectify the stepped down voltage. If the AC source is interrupted, Q17 and Q18 are biased off which turns offs the synchronous rectifier transistors Q12 - Q15 regardless of a secondary bias. In figure 18, multiple synchronous rectifier transistors are used which allows the high frequency battery charger to deliver a higher current to an external load. In this configuration, two or more parallel synchronous rectifier switches also may be used in alternative embodiments to deliver more or less current.
[00110] Figure 19 illustrates an alternative exemplary output that may be used with the exemplary systems and methods described above. In this alternative, a transistor Q51 is coupled in parallel to a high current output switch which may be a relay. The relay allows a relatively low power signal received at node M, to route a high-current to an external load, such as a battery. A high resolution output is achieved by connecting the base of transistor Q51 to a pulse width modulated source through node X. The frequency and/or duration of the pulses that drive transistor Q51 may provide a large or unlimited control of the level of charging current delivered to an external load. Although such control may be used in an absorption charge, absolute charge, a float charge, or equalization charge mode as shown, when the emitter of Q51 is coupled to a separate or secondary charge source, the high resolution control may also be used in a bulk charge or start charge mode.
[00111] In one exemplary embodiment, a processor andlor a pulse width modulator drive the bases of Q51 and Q5. In this embodiment, node Y may be connected to a negative output of the secondary of transformer T1 and node G may be connected to a positive output of the secondary of transformer Tl .
(00112] Figure 20 illustrates a partial alternative exemplary drive circuit that may be used with the exemplary systems and methods described above. In one exemplary embodiment, figure 20 may replace U1, C6, C107, C108, 8121, 8122, R30, R31, C11, QS
and Q6 of figure 5, with node Z coupled to a control circuit or processor and node W
coupled to 8123.
(00113] In this partial alternative drive circuit, a switch QS controls the response time of the drive logic by switching a capacitor Cl 1 into and out of circuit. When there is a need for the high frequency battery charger to respond quickly to current transients or continuous high.current conditions, Q60 is biased off. With Q60 turned off, C11 is removed from the circuit, which lowers the time constant associated with the dead time control (DTC) input of the pulse width modulator Ul. When protection against current spikes, transients and/or other conditions that require a fast response is needed, the dead-time control can be set or pr ogrammed to provide from 0% to about 100% dead time.
[00114] In normal operating conditions, Q60 is biased on bringing C11 in circuit. .
With C 11 in circuit, the dead time control unit provides a small dead time by connectingC 11 to R26. In an exemplary embodiment, Q60 is biased on when the exemplary high frequency battery charger is sourcing or driving a small charging current to an external load. The addition of the capacitor makes the drive logic more stable to current transients. In a low current charging mode, a spark may not be dangerous to a user because the high frequency battery charger may not be sourcing a continuous or a transitory high current.
Thus, there may not be a need to dampen or turn off the output of the high frequency battery charger.
[00115] However, when the high frequency battery charger is sourcing a high current, such as a bulk or starting current, the exemplary drive circuit may require a more responsive dead time control to improve the frequency response of the pulse width modulator Ul and the high frequency battery charger. In high current sourcing conditions, there may be a need to respond more quickly to current variations and current spikes by shutting down the output of the exemplary high frequency battery charger.
[00116] The exemplary systems and methods convert an AC-line voltage to a high frequency square wave, which is then transformed into a desired DC voltage level through a single high frequency transformer. In some alternative exemplary battery chargers two or more high frequency transformers may be used. In some exemplary high frequency battery chargers, the multiple high frequency transformers operate contemporaneously to generate a charging current. In other exemplary high frequency battery chargers, separate high frequency transformers operate exclusively to generate different charging current according to a selected charging mode.
(00117] Many other alternatives are also encompassed within the embodiments.
These embodiments may select between different battery types, detect voltage drops when determining when to initiate an engine start mode; determine and display the charge level or percentage charge level of a battery during a test or a charge mode; determine and display the remaining charge time in a charging cycle; calculate and display the amount of current or charge flowing to the battery (e.g., through a digital current value); have an automatic start and stop charging capability that may be initiated when power is interrupted; have an automatic voltage (e.g. 6 or 12 volts) or battery type detection, have a variable overtime fault detection; compare measured battery voltages in different time intervals to detect battery faults and have a current ramping function to charge a battery quickly. In addition each of the embodiments described above may include ground and output filters or noise filters having cutoff frequencies or pass bands that limit the transmission of radio frequency signals.
(00118] The above-described high frequency battery chargers describe many features and functions. In any one of the above-described exemplary battery chargers, any combination of features and functions may be included within any of the exemplary high frequency battery chargers or methods illustrated in the drawings or described above.
Moreover, while the exemplary high frequency battery chargers have been described in automotive and marine applications, the invention may be used in any other application.
Each application may use separate monitoring cables to monitor a charging current and voltage passed to the load or connect the monitoring cables with the respective charging outputs as shown in figure 7.
[00119] The above-described battery chargers may interface many networks, such as a publicly accessible (e.g., Internet) or a privately accessible network (e.g., WAN, LAN). The battery chargers may also interface one or more in-vehicle data networks. Such networks may include multiple Assembly Line Data linlc (ALDL) buses, Entertainment and Comfort buses (E~r.C), Controller Area Networks (CAN), or a combination of any in-vehicle data network. When connected to an in-vehicle data network, the above-described battery chargers may accept and/or issue commands, monitor vehicle or battery charger functions, and enable vehicle and charger functionality. Moreover, like the equalization charge, the bulls charge mode, the absorption or acceptance charge mode, and the float or trickle charge mode may provide a continuous or analog charge or a series of pulse charges of constant or varying amplitude in some exemplary high frequency battery chargers. Such charges may reverse a buildup of contaminants that may build up on a battery's electrodes.
[00120] The systems and method described above provide highly efficient high frequency battery chargers that maintain the charging levels of a battery within a desired range. The systems and methods provide high frequency mufti-stage charging to ensure that a battery reaches and sustains its full charge level. Depending on the battery type or a user's selection, a charging cycle of the system and method may be automatically terminated. The output of the high frequency charger is protected against short circuits, highly discharged batteries, and defective batteries. The high frequency battery chargers provide a pulse charge that may brealc up contaminants, chemicals, or sulfate layers that may build up on a battery's electrodes.
[00121] While some embodiments of the invention have been described, it should be apparent that many more embodiments and implementations are possible and are within the scope of this invention. It is intended that the foregoing detailed description be regarded as illustrative rather than limiting, and that it be understood that it is the following claims, including all equivalents, that are intended to define the spirit and scope of this invention.

Claims (43)

1. A high frequency battery charger, comprising:
a converter that transforms a DC voltage into a high frequency AC voltage;
a drive logic that controls a conversion of the high frequency AC voltage by producing a train of pulses; and control logic that adjusts an output of the converter to maximize a charging cycle of a battery.

2. The high frequency battery charger of claim 1 wherein the converter comprises a high frequency transformer.

3. The high frequency transformer of claim 2 further including a switch for coupling a source to the converter.

4. The high frequency transformer of claim 3 further comprising a second and a third switch that provide a current path to a primary winding, the second and third switch being directly connected to the primary winding.

5. The high frequency battery charger of claim 1 wherein the control logic is programmed to provide a bulk charge, an absorption charge, a maintenance charge, a float mode monitoring and a desulfation charge.

6. The high frequency battery charger of claim 5 wherein the desulfation charge comprise a series of pulse charges that reverses a build up of contaminants on a load's electrodes.

7. The high frequency battery charger of claim 5 wherein the desulfation charge comprise a series of pulse charges or a high charging voltage that reverses a build up of contaminants on a load's electrodes.

8. The high frequency battery charger of claim 1 wherein the high frequency charger includes a sensor that provides spark resistant protection in a reverse polarity connection.

9. The high frequency battery charger of claim 1 further comprising a switch coupled to the control logic for passing a charging current to a load only when the load is correctly connected to output charging connectors.

10. The high frequency battery charger of claim 1 further including a meter that measures a charging current.

11. The high frequency battery charger of claim 1 wherein the converter and driver are optically isolated from the control logic.

12. The high frequency battery charger of claim 1 further comprising a second converter that transforms the high frequency AC voltage into a second DC voltage.

13. The high frequency battery charger of claim 12 wherein the second converter comprises a bridge rectifier.

14. The high frequency battery charger of claim 1 further comprising a display coupled to the control logic.

15. The high frequency battery charger of claim 1 further comprising a sensor that controls the drive logic by monitoring a current flowing through a high frequency transformer.

16. The high frequency battery charger of claim 15 wherein the sensor controls the drive logic by monitoring the current flowing through a primary winding of the high frequency transformer.

17. The high frequency batter charger of claim 15 further comprising a synchronous converter that transforms the high frequency AC voltage into a low frequency direct current.

18. A high frequency charger for charging a battery, comprising:
a first converter that transforms an alternating current into a into a low frequency direct current, and then into a high frequency alternating output current;
a synchronous converter that transforms the high frequency alternating output current to a second low frequency direct current;
a drive logic that controls a transformation of high frequency alternating output current into a second low frequency direct current signal; and a processor that adjusts a level of charging current of the synchronous converter that passes onto a load.

19. The high frequency battery charger of claim 18 wherein the first converter comprises a high frequency transformer.

20. The high frequency transformer of claim 19 further including a switch for coupling the alternating current to the first converter.

21. The high frequency transformer of claim 20 further comprising a second and a third switch that provide a current path to a primary winding of the high frequency transformer, the second and third switch being directly connected to the primary winding.

22. The high frequency battery charger of claim 18 wherein the processor is programmed to provide a bulk charge, an absorption charge.

23. The high frequency battery charger of claim 18 wherein the equalization charge comprise a series of pulse charges that reverses a build up of contaminants on a load's electrodes.

24. The high frequency battery charger of claim 18 wherein the high frequency charger includes a sensor that provides a spark resistant protection in a reverse polarity connection of the load.

25. The high frequency battery charger of claim 18 further comprising a switch coupled to the processor for passing a charging current to the load only when the load is correctly connected to output charging connectors.

26. The high frequency battery charger of claim 18 further including a meter coupled to the processor.

27. The high frequency battery charger of claim 18 wherein the first converter and drive logic are optically isolated from the processor.

28. The high frequency battery charger of claim 18 wherein the first converter comprises a bridge rectifier.

29. The high frequency battery charger of claim 18 further comprising a display coupled to the processor.

30. The high frequency battery charger of claim 18 further comprising a sensor that controls the drive logic by monitoring a current flowing through a high frequency transformer.

31. The high frequency battery charger of claim 30 wherein the sensor controls the drive logic by monitoring the current flowing through a primary winding of the high frequency transformer.

32. The high frequency battery charger of claim 30 wherein the charging current is a pulsating current.

33. The high frequency battery charger of claim 18 further comprising a temperature sensor coupled to the processor, an output of the temperature sensor being used to adjust the level of charging current that passes to the load.

34. The high frequency battery charger of claim 18 further comprising a medium that may be read by the processor to detect a defective battery.

35. A method of transforming an AC input into a direct current output used to charge a rechargeable battery comprising:
transforming an AC input into a first DC output;
transforming the first DC output into a high frequency AC output;
transforming the high frequency AC output into a second DC output; and passing a charging current to a load only when the load is correctly connected to an output of a charging connector.

36. The method of claim 35 wherein the act of transforming the first DC input into a high frequency AC output comprises actuating a plurality switches coupled to a primary of a high frequency transformer.

37. The method of claim 35 further comprising the act of monitoring the charging current with a processor.

38. The method of claim 35 further comprising the act of providing a spark resistance when a load is connected in a reverse polarity.

39. The method of claim 35 wherein the act of passing the charging current comprises passing the charging current onto a battery only when the charging current is below a predetermined threshold.

40. The method of claim 35 wherein the charging current comprises a pulsating current.

41. A high frequency battery charger that responds to an actuation of a switch comprising:
a switch logic configured to display an actuation of a switch; and a processor configured to process data contemporaneously with the actuation of the switch, wherein the processor is configured to enable a single state with each actuation of the switch.

42. The high frequency charger of claim 41 further comprising a battel-y coupled to the processor, wherein the processor compares a first average battery voltage measured during a first predetermined time period to a second average battery voltage measured during a second predetermined time period when detecting a disconnected battery condition.

43. The high frequency battery charger of claim 42 wherein the first predetermined time period comprises about two seconds and the second predetermined time period comprises about one quarter of a second.