Active cell balancing

Abstract

A system includes a first battery (204), a second battery (202), an integrated circuit (330), a capacitor (320), and an inductor (318). The first battery (204) has a first battery terminal and a second battery terminal. The second battery (202) has a third battery terminal and a fourth battery terminal. The second battery terminal is coupled to the third battery terminal. The integrated circuit (330) includes a first transistor (316), a second transistor (314), a third transistor (312), and a fourth transistor (310). The first transistor (316) is coupled between the first battery terminal and a capacitor terminal. The second transistor (314) is coupled between the capacitor terminal and the second battery terminal. The third transistor (312) is coupled between the third battery terminal and an inductor terminal. The fourth transistor (310) is coupled between the inductor terminal and the fourth battery terminal. The capacitor (320) and the inductor (318) are coupled in series. The capacitor (320) is coupled to the capacitor terminal, and the inductor (318) is coupled to the inductor terminal.

Description

BACKGROUND OF THE INVENTION

[0001] A high-voltage energy storage system may include a number of energy storage cells, such as batteries, connected in series. The capacity of the stacked cells may vary due to internal factors (e.g., internal impedance) or external factors (e.g., temperature). This variation in capacity may result in differences in charging and discharging of the cells, which may lead to charge imbalance across the entire cell stack and limit the energy capacity of the system. SUMMARY OF THE INVENTION

[0002] In one example, an integrated circuit (IC) includes a first transistor, a second transistor, a third transistor, a fourth transistor, and a control circuit. The first transistor is coupled between a first battery terminal and a capacitor terminal. The first transistor has a first transistor control terminal. The second transistor is coupled between the capacitor terminal and a second battery terminal. The second transistor has a second transistor control terminal. The third transistor is coupled between a third battery terminal and an inductor terminal. The third transistor has a third transistor control terminal. The third battery terminal is coupled to the second battery terminal. The fourth transistor is coupled between the inductor terminal and a fourth battery terminal. The fourth transistor has a fourth transistor control terminal. The control circuit has a control input and first, second, third, and fourth control outputs. The first control output is coupled to the first transistor control terminal, the second control output is coupled to the second transistor control terminal, the third control output is coupled to the third transistor control terminal, and the fourth control output is coupled to the fourth transistor control terminal.

[0003] In another example, a method includes connecting a capacitor and an inductor between a first battery terminal and a second battery terminal of a first battery cell to store a first voltage across the capacitor. The capacitor terminal of the capacitor is connected to the first battery terminal, and the inductor terminal of the inductor is connected to the second battery terminal. The method further includes disconnecting the inductor terminal from the second battery terminal, connecting the inductor terminal to the first battery terminal to store a first voltage across the inductor, and disconnecting the capacitor terminal from the first battery terminal. The method further includes connecting the capacitor terminal to a third battery terminal of a second battery cell to transfer charge from the first battery cell to the second battery cell at a rate based on the first voltage and the inductance of the inductor.

[0004] In another example, a system includes a first battery, a second battery, an integrated circuit, a capacitor, and an inductor. The first battery has a first battery terminal and a second battery terminal. The second battery has a third battery terminal and a fourth battery terminal. The second battery terminal is coupled to the third battery terminal. The integrated circuit includes a first transistor, a second transistor, a third transistor, and a fourth transistor. The first transistor is coupled between the first battery terminal and the capacitor terminal. The second transistor is coupled between the capacitor terminal and the second battery terminal. The third transistor is coupled between the third battery terminal and the inductor terminal. The fourth transistor is coupled between the inductor terminal and the fourth battery terminal. The capacitor and the inductor are coupled in series. The capacitor is coupled to the capacitor terminal, and the inductor is coupled to the inductor terminal.

[0005] In yet another example, a battery assembly includes a first battery module, a second battery module, a first transistor, a second transistor, a third transistor, a fourth transistor, and a control circuit. The first battery module includes a first module terminal, a second module terminal, a first battery, and a second battery. The first battery and the second battery are coupled in series between the first module terminal and the second module terminal. The second battery module includes a third module terminal, a fourth module terminal, a third battery, and a fourth battery. The third battery and the fourth battery are coupled in series between the third module terminal and the fourth module terminal. The third module terminal is coupled to the second module terminal. The first transistor is coupled between the first module terminal and the first resonant component terminal. The first transistor has a first transistor control terminal. The second transistor is coupled between the first resonant component terminal and the second module terminal. The second transistor has a second transistor control terminal. The third transistor is coupled between the third module terminal and the second resonant component terminal. The third transistor has a third transistor control terminal. The fourth transistor is coupled between the second resonant component terminal and the fourth module terminal. The fourth transistor has a fourth transistor control terminal. The control circuit has a control input and first, second, third, and fourth control outputs. The first control output is coupled to the first transistor control terminal. The second control output is coupled to the second transistor control terminal. The third control output is coupled to the third transistor control terminal. The fourth control output is coupled to the fourth transistor control terminal. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1A and 1B illustrates an example of charge redistribution in a battery module that includes active cell balancing.

[0007] Figure 2 is a block diagram of an example battery module that includes active cell balancing.

[0008] Figure 3 is Figure 2 a schematic diagram of an example of an active cell balancing circuit of

[0009] Figure 4 is Figure 3 a graph of example signals in an active cell balancing circuit, illustrating charge transfer between battery cells.

[0010] Figure 5 and 6 is a schematic diagram of an example active cell balancing circuit with input filtering.

[0011] Figure 7 is illustrative of Figure 2 an example block diagram of charge transfer from one battery cell to two battery cells in a battery module of

[0012] Figure 8 is illustrative of Figure 2 an example block diagram of multiple simultaneous charge transfers between battery cells of a battery module of

[0013] Figure 9A and 9B illustrate charge transfer examples across Figure 2 six battery cells in a battery module of

[0014] Figure 10A and 10B illustrate charge transfer examples across Figure 2 three battery cells in a battery module of

[0015] Figure 11A and 11B illustrate examples of simultaneous charge transfer across Figure 2 three battery cells and two battery cells in a battery module of

[0016] Figure 12A and 12B illustrate another example of simultaneous charge transfer across Figure 2 three battery cells and two battery cells in a battery module of

[0017] Figure 13 is a block diagram of an example of a part of an active cell balancing circuit that includes multiple active cell balancing integrated circuits coupled in series.

[0018] Figure 14 is a schematic diagram of an active cell balancing circuit that includes a disconnect switch between LC circuits.

[0019] Figure 15 is a schematic diagram of an active cell balancing circuit configured for two-phase operation.

[0020] Figure 16 is a flowchart of an example method for active cell balancing.

[0021] Figure 17 It is a schematic diagram of another example of an active cell balancing circuit.

[0022] Figure 18A and 18B illustrates an example of an active cell balancing circuit that uses Figure 17 to simultaneously transfer charge between battery cells.

[0023] Figure 19 is a schematic diagram of an example of an active cell balancing circuit that includes a disconnect switch Figure 17 of

[0024] Figure 20 is a block diagram of an example of an active cell balancing circuit that includes a parallel capacitor network Figure 17 of

[0025] Figure 21 is a schematic diagram of an active cell balancing circuit configured for two-phase operation based on Figure 17 of

[0026] Figure 22 It is a schematic diagram of another example of an active cell balancing circuit.

[0027] Figure 23 is a schematic diagram of an example of an active cell balancing circuit that includes a disconnect switch Figure 22 of

[0028] Figure 24 is a schematic diagram of an active cell balancing circuit configured for two-phase operation based on Figure 22 of

[0029] Figure 25 It is a schematic diagram of another example of an active cell balancing circuit.

[0030] Figure 26 is a schematic diagram of an example of an active cell balancing circuit that includes a disconnect switch Figure 25 of

[0031] Figure 27 is a schematic diagram of an active cell balancing circuit configured for two-phase operation based on Figure 25 of

[0032] Figure 28 is a block diagram of a battery assembly that includes balancing across battery modules. Detailed Description

[0033] A high-voltage battery module includes a plurality of low-voltage battery cells coupled in series. The series connection of the low-voltage battery cells limits the capacity of the battery module to the capacity of the weakest low-voltage battery cell. For example, when the battery pack discharges, the weakest cell discharges at the highest rate and has the lowest state of charge (SOC). When the SOC of this cell reaches its lowest allowable value (e.g., the lowest value allowed by the battery manager coupled to the cell), the battery module can be disconnected and the charge stored in the other battery cells of the battery pack is not used. Similarly, when the battery module is charged, charging can be stopped when the battery cell with the smallest capacity is fully charged, leaving the stronger cells partially charged.

[0034] Active cell balancing is a technique for managing the SOC of battery cells in a battery module. Active cell balancing redistributes charge across the cells of the battery module to reduce the charge differences between the battery cells. For example, an active balancing circuit can transfer charge from a battery cell with a higher SOC to a battery cell with a lower SOC. Figure 1A and 1B illustrates an example of charge redistribution in a battery module that includes active cell balancing. In Figure 1A , battery cells 102 and 104 are being charged. Battery cell 102 is weaker than battery cell 104. For example, battery cell 102 charges and discharges faster than battery cell 104. The active balancing circuit system moves charge from battery cell 102 to battery cell 104 during charging to allow both battery cell 102 and battery cell 104 to be fully charged. Without active balancing, 102 could be fully charged before battery cell 104, and charging could stop before battery cell 104 is fully charged. Thus, the active balancing circuit system increases the total charge stored in the battery module.

[0035] In Figure 1B , battery cells 102 and 104 are discharging. Battery cell 102 discharges faster than battery cell 104. The active balancing circuit system moves charge from battery cell 104 to battery cell 102 during discharging to allow both battery cell 102 and battery cell 104 to discharge to the same extent. Without active balancing, battery cell 102 could discharge before battery cell 104, and the battery module could be disconnected before battery cell 104 discharges (e.g., the discharge of the battery module is interrupted). Thus, the active balancing circuit system increases the total charge provided by the battery module.

[0036] Figure 2 is a block diagram of an example battery module 200 that can perform active cell balancing. Battery module 200 includes a plurality of battery cells. Battery cells 202 and 204 are in Figure 2Shown in the figure, but the battery module 200 may include more than two battery cells. The battery module 200 also includes an active cell balancing circuit 206 and a battery manager circuit 208. The active cell balancing circuit 206 and the battery manager circuit 208 are coupled to the battery cell 202 and the battery cell 204. The battery manager circuit 208 monitors the voltages of the battery cell 202 and the battery cell 204 and the current flowing from the battery cell 202 and the battery cell 204 to determine the SOC of the battery cell 202 and the battery cell 204. The battery manager circuit 208 may include measurement circuitry (e.g., an analog-to-digital converter, sampling circuitry, sensing circuitry, etc.) to measure the voltages and currents of the battery cell 202 and the battery cell 204. The battery manager circuit 208 may include a microcontroller or other computing circuitry configured to determine the SOC based on the current and voltage measurements.

[0037] Based on the SOC of the battery cell 202 and the battery cell 204, the battery manager circuit 208 may generate an active balance control signal (AB_CTL). The AB_CTL may specify transferring charge from the battery cell 202 to the battery cell 204 if the SOC of the battery cell 202 is greater than the SOC of the battery cell 204, or may specify transferring charge from the battery cell 204 to the battery cell 202 if the SOC of the battery cell 204 is greater than the SOC of the battery cell 202. For example, the AB_CTL may specify the rate and duration of charge transfer between the battery cell 202 and the battery cell 204 based on the SOC of the battery cell 202 and the battery cell 204.

[0038] The active cell balancing circuit 206 receives the AB_CTL and transfers charge between the battery cell 202 and the battery cell 204 based on the balancing parameters specified by the AB_CTL (e.g., charge transfer source, charge transfer destination, charge transfer rate and charge transfer duration, start transfer, stop transfer, and / or other parameters). As mentioned above, the battery module 200 may include more than two battery cells, and the active cell balancing circuit 206 may transfer charge between any of the battery cells of the battery module 200.

[0039] Figure 3 is a schematic diagram of an example of the active cell balancing circuit 206 (or a part thereof for 2 adjacent battery cells). Figure 3Also shown are adjacent battery cells 202 and 204 coupled to the active cell balancing circuit 206. The active cell balancing circuit 206 includes a half-bridge circuit 302, a half-bridge circuit 304, an inductor-capacitor (LC) circuit 306, and a control circuit 308. The half-bridge circuit 302 is coupled in parallel with the battery cell 202 and includes a first battery terminal coupled to the first terminal of the battery cell 202 and a second battery terminal coupled to the second terminal of the battery cell 202. Similarly, the half-bridge circuit 304 is coupled in parallel with the battery cell 204 and includes a first battery terminal coupled to the first terminal of the battery cell 204 and a second battery terminal coupled to the second terminal of the battery cell 204.

[0040] Each half-bridge circuit includes a pair of transistors. The transistors can be n-channel field effect transistors (NFETs). The half-bridge circuit 302 includes transistors 310 and 312. The first terminal (e.g., source) of the transistor 310 is coupled to the second battery terminal, and the second terminal (e.g., drain) of the transistor 310 is coupled to the switching node 332. The capacitor 322 represents the drain-to-source capacitance of the transistor 310. The first terminal (e.g., source) of the transistor 312 is coupled to the switching node 332, and the second terminal (e.g., drain) of the transistor 312 is coupled to the first battery terminal. The capacitor 324 represents the drain-to-source capacitance of the transistor 312.

[0041] The half-bridge circuit 304 includes transistors 314 and 316 and a switching node 334. The first terminal (e.g., source) of the transistor 314 is coupled to the first terminal of the battery cell 204, and the second terminal (e.g., drain) of the transistor 314 is coupled to the switching node 334. The capacitor 326 represents the drain-to-source capacitance of the transistor 314. The first terminal (e.g., source) of the transistor 316 is coupled to the switching node 334, and the second terminal (e.g., drain) of the transistor 316 is coupled to the second terminal of the battery cell 204. The capacitor 328 represents the drain-to-source capacitance of the transistor 316.

[0042] The LC circuit 306 is coupled between the switching node 332 and the switching node 334. The LC circuit 306 includes an inductor 318 and a capacitor 320 coupled in series. The capacitor 320 capacitively couples the half-bridge circuit 302 and the half-bridge circuit 304. The capacitance of the capacitor 320 and the inductance of the inductor 318 can be relatively small. For example, in some embodiments of the active cell balancing circuit 206, the inductance of the inductor 318 can be 50 nanohenries, and the capacitance of the capacitor 320 can be 3 microfarads. The voltage across the transistor 310, the transistor 312, the transistor 314, the transistor 316, the inductor 318, or the capacitor 320 can be limited to approximately the voltage of a single battery cell. Thus, the rated voltage of these components can be relatively low.

[0043] The control circuit 308 receives AB_CTL provided by the battery manager circuit 208 ( Figure 2 ), and generates drive signals for controlling transistors 310, 312, 314, and 316. The control circuit 308 generates drive signals C1, C2, and and provides the drive signals at an output of the control circuit 308, the output being coupled to the control inputs (e.g., gates) of transistors 310, 312, 314, and 316. may be an inverted version of C1, where there is a dead time interval between the edges of C1 and , and C2 and may be phase-shifted versions of C1 and . By controlling the switching of transistors 310, 312, 314, and 316 by taking advantage of a selected phase shift between the drive signals provided to the half-bridge circuit 302 and the half-bridge circuit 304, the active cell balancing circuit 206 can transfer charge from the battery cell 202 to the battery cell 204, or from the battery cell 204 to the battery cell 202. In some instances, the drive signals C1, C2, and may each have a duty cycle of 50%. In some instances, when the imbalance between the cell voltages is high, the duty cycle may deviate from 50% to improve efficiency. In some instances, discontinuous conduction mode (DCM) operation may also be performed in extreme cases of voltage imbalance between the battery cells to reduce losses.

[0044] In some instances of the active cell balancing circuit 206, the control circuit 308 may be distributed across the half-bridge circuits. For example, a portion of the control circuit 308 that generates the control signals C1 and may be disposed in a first sub-circuit having the half-bridge circuit 302, and a portion of the control circuit 308 that generates the control signals C2 and may be disposed in a second sub-circuit having the half-bridge circuit 304. In the case where the control circuit 308 is distributed across the half-bridge circuits, each portion of the control circuit 308 may receive transfer parameters (e.g., source, sink, and current) via AB_CTL and adjust the phase of the generated control signals to maintain a specified current.

[0045] The half-bridge circuit 302, the half-bridge circuit 304, and the control circuit 308 may be incorporated into an integrated circuit 330. Some instances of the integrated circuit 330 may also include an inductor 318. Instances of the integrated circuit 330 may include any number of half-bridge circuits (e.g., the half-bridge circuit 302, the half-bridge circuit 304) coupled in series, and a control circuit 308 configured to control the half-bridge circuits.

[0046] Figure 4 is a graph of the signals in the active cell balancing circuit 206, illustrating the transfer of charge from battery cell 202 to battery cell 204 during the switching cycles of half-bridge circuits 302 and 304. During interval 402, the control circuit 308 provides and in a first state to turn on transistors 310 and 314, and provides C1 and C2 in a second state to turn off transistors 312 and 316. The voltage across transistors 310 and 314 is zero or near zero. The current i B,AC1 is negative.

[0047] During interval 404, the control circuit 308 provides in a first state to turn on transistor 314, and provides C1 and C2 ( transitioning from the second state to the first state) to turn off transistors 310, 312, and 316. Transistor 312 can be turned off in a zero-voltage switching condition. The voltage across transistor 310 increases.

[0048] During interval 406, after the voltage across transistor 310 has risen to a selected value, the control circuit 308 can provide C1 in a first state to turn on transistor 312. The current i B,AC1 flows through transistor 312 due to the battery voltage across inductor 318. In this configuration, transistors 310 and 316 are off, and transistors 312 and transistor 314 are on to provide a path for current flow. As described above, capacitor 320 can provide capacitive isolation between adjacent battery cells and can have a relatively low voltage tolerance (e.g., 5 volts). The voltage across capacitor 320 can be the average of the voltage v1 across battery cell 202 and the voltage v2 across battery cell 204. The voltage across inductor 318 has a polarity opposite to that of the voltage across capacitor 320 (such that the total voltage is zero since the switching nodes 334 and 332 are shorted together through transistors 314 and 312), causing the current flowing through inductor 318 (i B,AC1 ) to increase (ramp up), and the ramp rate can be determined by the inductance of inductor 318. The duration of interval 406 can determine the amount by which the current increases before it stops increasing and the amount of charge transfer.

[0049] During interval 408, after the current flowing into inductor 318 has increased to a selected value, the control circuit 308 can provide in a second state to turn off transistor 314. In this configuration, transistors 310, 314, and 316 are off, and transistor 312 is on. The voltage across transistor 314 increases.

[0050] In interval 410, after the voltage across transistor 314 has increased to a selected value, control circuit 308 can provide C2 in a first state to turn on transistor 316 in a zero-voltage switching situation. In this configuration, transistors 310 and 314 are off, and transistors 312 and 316 are on. The voltage across inductor 318 is zero, and the current (i B,AC1 ) through the inductor remains at (or near) the selected value. In interval 410 (the power transfer interval), charge is transferred from LC circuit 306 to battery cell 204. Thus, the charge transferred from battery cell 202 to LC circuit 306 is transferred to battery cell 204.

[0051] In interval 412, control circuit 308 can provide C1 in a second state to turn off transistor 312. The voltage across transistor 310 drops.

[0052] In interval 414, after the voltage across transistor 310 has dropped to a selected value, control circuit 308 can provide in a first state to turn on transistor 310 in a zero-voltage switching situation. The current i B,AC1 decreases and becomes negative.

[0053] In interval 416, when the current flowing through inductor 318 has dropped to a selected value, control circuit 308 can provide C2 in a second state to turn off transistor 316. The voltage across transistor 314 drops.

[0054] In interval 418, when the voltage across transistor 314 has dropped to a selected value, control circuit 308 can provide in a first state to turn on transistor 314 in a zero-voltage switching situation. In interval 418, active cell balancing circuit 206 is in the same state as interval 402 for performing successive power transfer cycles.

[0055] In Figure 4 , inductor 318 and capacitor 320 can form a resonant circuit and support soft switching, and the switching nodes (332 and 334) can commutate without discharging capacitors 322, 324, 326, and 328. This arrangement can accelerate the switching and allow the half-bridge circuits 302 and 304 to operate at a higher switching frequency, which in turn allows the devices of half-bridge circuits 302 and 304 to be made smaller. The increased switching frequency can also shorten the time that capacitor 320 blocks the DC voltage, which in turn can reduce the size of capacitor 320.

[0056] Although Figure 4Illustrate the transfer of charge from battery cell 202 to battery cell 204, but can be achieved by exchanging Figure 4 the timings of signals C1 and C1 in Figure 4 and the timings of signals C2 and C2 in

[0057] Figure 5 is a schematic hierarchical diagram of an example of an active cell balancing circuit 206 that includes an input filter. In Figure 5 the example, the active cell balancing circuit 206 includes half - bridge circuits 302, 304, 502, and 504 and LC circuits 306, 520, and 522. The active cell balancing circuit 206 can include any number of half - bridge circuits, where each half - bridge circuit is coupled to an adjacent half - bridge circuit through an LC circuit (e.g., an example of LC circuit 306). All the half - bridge circuits can be similar or identical, and all the LC circuits can be similar or identical. The half - bridge circuits 302, 304, 502, and 504 are respectively coupled to battery cells 202, 204, 508, and 510 via conductors represented as Z interconnect of.

[0058] The active cell balancing circuit 206 also includes an input filter circuit 506. The input filter circuit 506 includes capacitors 512, 514, 516, and 518. Capacitor 512 is coupled between the battery terminals of half - bridge circuit 504. Capacitor 514 is coupled between the battery terminals of half - bridge circuit 502. Capacitor 516 is coupled between the battery terminals of half - bridge circuit 304. Capacitor 518 is coupled between the battery terminals of half - bridge circuit 302. Generally, the input filter circuit 506 includes capacitors that are coupled between the battery terminals of each half - bridge circuit of the active cell balancing circuit 206. Each capacitor of the input filter circuit 506 blocks the DC voltage of a single battery cell. When transferring charge between two battery cells (e.g., from battery cell 202 to battery cell 510), the equivalent capacitance of the input filter circuit 506 is C / (j - 1), where C is the capacitance of each capacitor of the input filter circuit 506, and j is the number of capacitors of the input filter circuit 506 connected in series between the two battery cells (e.g., when transferring charge from battery cell 202 to battery cell 508, j = 3).

[0059] Figure 6 is similar to Figure 5 but is a schematic hierarchical diagram of an example of an active cell balancing circuit 206 that includes different input filtering. In Figure 6In [the circuit], the active cell balancing circuit 206 includes an input filter circuit 606 instead of the input filter circuit 506. The input filter circuit 606 includes capacitors 612, 614, 616, and 618. Capacitor 612 is coupled across battery cells 510, 508, 204, and 202. Capacitor 614 is coupled across battery cells 508, 204, and 202. Capacitor 616 is coupled across battery cells 204 and 202. Capacitor 618 is coupled across battery cell 202. Each of the capacitors blocks the DC voltage of the series-connected batteries across which it is connected. When transferring charge between two battery cells, the equivalent capacitance of the input filter circuit 606 is C (the capacitance of one capacitor of the input filter circuit 606). Thus, the input filter circuit 606 can reduce the AC signal path capacitance between battery cells relative to the input filter circuit 506.

[0060] In an example of the active cell balancing circuit 206, the current transferred from one battery cell to another can be modeled as:

[0061]

[0062] where:

[0063] V is the battery voltage;

[0064] L is the inductance of an inductor such as inductor 318;

[0065] is the phase shift between the driver signals (e.g., C1 and C1) driving the half-bridge circuit; and

[0066] fsw is the switching frequency.

[0067] Thus, the phase shift generated by the control circuit 308 to provide a selected charge transfer between battery cells can be determined as:

[0068]

[0069] Figure 7 is a block diagram illustrating an example of charge transfer from one battery cell to two battery cells in the battery module 200. In Figure 7 the battery module 200 includes battery cells 202, 204, and 508 respectively coupled to half-bridge circuits 302, 304, and 502, and LC circuits 306 and 520 coupled to the half-bridge circuits. The half-bridge circuit 502 can be the same as the half-bridge circuit 302, and the LC circuit 520 can be the same as the LC circuit 306. In Figure 7In an example, charge can be transferred from battery cell 202 to battery cell 204 and battery cell 508 simultaneously. The drive signals provided to half-bridge circuits 302, 304, and 502 cause 70% of the charge provided by battery cell 202 to be directed to battery cell 204, and 30% of the charge provided by battery cell 202 to be directed to battery cell 508. The amount of charge directed to each of battery cell 204 and battery cell 508 is determined by the phases of drive signals C1, C2, and C3 provided by control circuit 308 to half-bridge circuits 302, 304, and 502. Control circuit 308 can determine the phase shift applied to C2 (relative to C1) as:

[0070]

[0071] where I 1A specifies that the total current flowing from battery cell 202 to battery cell 204 and battery cell 508 is 1 ampere.

[0072] Control circuit 308 can determine the phase shift applied to C3 (relative to C2) as:

[0073]

[0074] where I 0.3A specifies that the current flowing from battery cell 202 to battery cell 508 is 0.3 amperes. In some examples, control circuit 308 can be coupled to a current sensor that senses the amount of current flowing between the two half-bridges. Control circuit 308 can set the phase shifts of the switches of the two half-bridges based on the sensed current to provide closed-loop control of the current.

[0075] Figure 8 is a block diagram illustrating an example of multiple charge transfers between battery cells of battery module 200. In Figure 8 battery module 200 includes battery cells 202, 204, 802, 804, 806, 818, 820, 822, and 824, half-bridge circuits 302, 304, 808, 810, 812, 826, 828, 830, and 832 coupled to the battery cells, and LC circuits 306, 814, 816, 834, 836, and 838 coupled to the half-bridge circuits. Half-bridge circuits 808, 810, 812, 826, 828, 830, and 832 can be the same as half-bridge circuit 302, and LC circuits 814, 816, 834, 836, and 838 can be the same as LC circuit 306. Battery module 200 can also include batteries, half-bridge circuits, and LC circuits not shown. In Figure 8Among them, charge is transferred from battery cell 202 to battery cell 204, from battery cell 802 to battery cell 806, and from battery cell 824 to battery cell 818. Multiple charge transfers can occur simultaneously. The control circuit 308 controls the transfer by setting the phase of the drive signal provided to the half-bridge circuit. In Figure 8 Among them, the drive signal provided to the half-bridge circuit 304 is shifted to the right (delayed) relative to the drive signal provided to the half-bridge circuit 302 to transfer charge from battery cell 202 to battery cell 204.

[0076] In the charge transfer to battery cell 806, the drive signal provided to the half-bridge circuit 810 is shifted to the right (delayed) relative to the drive signal provided to the half-bridge circuit 808. The drive signal provided to the half-bridge circuit 812 is shifted to the right (delayed) relative to the drive signal provided to the half-bridge circuit 810 to transfer charge from battery cell 802 to battery cell 806.

[0077] In the charge transfer to battery cell 818, the drive signal provided to the half-bridge circuit 830 is shifted to the right (delayed) relative to the drive signal provided to the half-bridge circuit 832. The drive signal provided to the half-bridge circuit 828 is shifted to the right (delayed) relative to the drive signal provided to the half-bridge circuit 830. The drive signal provided to the half-bridge circuit 826 is shifted to the right (delayed) relative to the drive signal provided to the half-bridge circuit 828 to transfer charge from battery cell 824 to battery cell 818.

[0078] Figure 9A and 9B illustrate examples of charge transfer across six battery cells in the battery module 200. In Figure 9A Among them, the battery module 200 includes battery cells 202, 204, 906, 908, 910, and 912 respectively coupled to half-bridge circuits 302, 304, 914, 916, 918, and 920. LC circuits 306, 922, 924, 926, and 928 are coupled to the half-bridge circuits. The half-bridge circuits 914, 916, 918, and 920 can be the same as the half-bridge circuit 302, and the LC circuits 922, 924, 926, and 928 can be the same as the LC circuit 306. In Figure 9A Among them, charge is transferred from battery cell 202 to battery cell 912. Figure 9BDescribe the switches in half - bridge circuits 302, 304, 914, 916, 918, and 920 (e.g., the control circuit 308 provides drive signals to half - bridge circuits 302, 304, 914, 916, 918, and 920). The switch in half - bridge circuit 304 is delayed (has a phase shift) relative to the switch in half - bridge circuit 302. The switch in half - bridge circuit 914 is delayed (has a phase shift) relative to the switch in half - bridge circuit 304. The switch in half - bridge circuit 916 is delayed (has a phase shift) relative to the switch in half - bridge circuit 914. The switch in half - bridge circuit 918 is delayed (has a phase shift) relative to the switch in half - bridge circuit 916. The switch in half - bridge circuit 920 is delayed (has a phase shift) relative to the switch in half - bridge circuit 918. An equal phase shift can be applied across the half - bridge circuits. For example, the phase shift between the switches of half - bridge circuit 302 and half - bridge circuit 304 is the same as the phase shifts between the switches of half - bridge circuit 304 and half - bridge circuit 914, half - bridge circuit 914 and half - bridge circuit 916, half - bridge circuit 916 and half - bridge circuit 918, and half - bridge circuit 918 and half - bridge circuit 920.

[0079] With this switch arrangement, charge can be transferred from battery cell 202 to battery cell 204, from battery cell 204 to battery cell 906, from battery cell 906 to battery cell 908, from battery cell 908 to battery cell 910, and from battery cell 910 to battery cell 912, which causes a net charge transfer from battery cell 202 to battery cell 912. Multiple charge transfers can occur simultaneously. This switch arrangement can also reduce the total inductance between a pair of half - bridge circuits through which charge transfer occurs. For example, for the charge transfer from battery cell 202 to battery cell 204 through half - bridge circuits 302 and 304, current flows through LC circuit 306 (and inductor 318) but not through other LC circuits. Additionally, for the charge transfer from battery cell 910 to battery cell 912, current flows through LC circuit 928 (and the inductor corresponding to inductor 318) but not through other LC circuits. By limiting the total inductance, during the phase shift of the switches between several pairs of half - bridges (e.g., at Figure 4Within the interval 406), the slew rate of the inductor current can also increase, which can also extend the duration of the power transfer interval 410 within each cycle and improve the efficiency of charge transfer. On the other hand, if the intermediate half-bridge between the half-bridges 302 and 920 does not switch, the current flowing from the half-bridge 302 to the half-bridge 920 may experience the combined inductance of the LC circuits 306, 922, 924, 926, and 928. As the total inductance increases, the slew rate of the inductor current during the phase shift of the switch between the half-bridges 302 and 920 can decrease, which shortens the duration of the power transfer interval 410 within each cycle and reduces the efficiency of charge transfer. Since the slew rate of the inductor current decreases, the switching frequency can also be reduced to provide a longer time, which can increase the size of the capacitors in the LC circuits between the half-bridge circuits.

[0080] Figure 10A and 10B An example illustrating charge transfer between three battery cells in the battery module 200. In Figure 10A , the battery module 200 is the same as the battery module shown in Figure 9A . In Figure 10A , charge is transferred from the battery cell 202 to the battery cell 906. Figure 10B An example illustrating switches in the half-bridge circuits 302, 304, 914, 916, 918, and 920 (e.g., the control circuit 308 provides drive signals to the half-bridge circuits 302, 304, 914, 916, 918, and 920). The switches in the half-bridge circuit 304 are delayed (phase shifted) relative to the switches in the half-bridge circuit 302. The switches in the half-bridge circuit 914 are delayed (phase shifted) relative to the switches in the half-bridge circuit 304. The switches in the half-bridge circuits 916, 918, and 920 are in the same phase as the switches in the half-bridge circuit 914. With this switching, charge is transferred from the battery cell 202 to the battery cell 906, and little or no charge is transferred from the battery cell 202 to the battery cells 204, 908, 910, or 912.

[0081] Figure 11A and 11B An example illustrating charge transfer across three battery cells and two battery cells in the battery module 200. In Figure 11A , the battery module 200 is the same as the battery module shown in Figure 9A . In Figure 11A , charge is transferred from the battery cell 202 to the battery cell 906, and from the battery cell 910 to the battery cell 908. Multiple charge transfers can occur simultaneously. Figure 11BDescribe the switches in half - bridge circuits 302, 304, 914, 916, 918, and 920 (e.g., the control circuit 308 provides drive signals to the half - bridge circuits 302, 304, 914, 916, 918, and 920). The switch in half - bridge circuit 304 is delayed (a phase shift occurs) relative to the switch in half - bridge circuit 302. The switch in half - bridge circuit 914 is delayed (a phase shift occurs) relative to the switch in half - bridge circuit 304. The switch in half - bridge circuit 916 is in the same phase as the switch in half - bridge circuit 914. The switches in half - bridge circuits 918 and 920 are in the same phase as the switch in half - bridge circuit 304. Using such switches, charge is transferred from battery cell 202 to battery cell 906, and little or no charge is transferred from battery cell 202 to battery cell 204. Charge is also transferred from battery cell 910 to battery cell 908, and no charge is transferred to or from battery cell 912.

[0082] Figure 12A and 12B Describe another example of charge transfer across three battery cells and two battery cells in battery module 200. In Figure 12A , battery module 200 is the same as the battery module shown in Figure 9A . In Figure 12A , charge is transferred from battery cell 202 to battery cell 906, and from battery cell 908 to battery cell 910. Multiple charge transfers can occur simultaneously. Figure 12B Describe the switches in half - bridge circuits 302, 304, 914, 916, 918, and 920 (e.g., the control circuit 308 provides drive signals to the half - bridge circuits 302, 304, 914, 916, 918, and 920). The switch in half - bridge circuit 304 is delayed (a phase shift occurs) relative to the switch in half - bridge circuit 302. The switch in half - bridge circuit 914 is delayed (a phase shift occurs) relative to the switch in half - bridge circuit 304. The switch in half - bridge circuit 916 is in the same phase as the switch in half - bridge circuit 914. The switches in half - bridge circuits 918 and 920 are in the same phase and are delayed (a phase shift occurs) relative to the switch in half - bridge circuit 916. Using such switches, charge is transferred from battery cell 202 to battery cell 906, and little or no charge is transferred from battery cell 202 to battery cell 204. Charge is also transferred from battery cell 908 to battery cell 910, and no charge is transferred to or from battery cell 912.

[0083] Figure 13 is a block diagram that is part of an example of battery module 200. In Figure 13In [description], the battery module 200 includes a plurality of integrated circuits 330. Each integrated circuit 330 may include a plurality of half-bridge circuits (half-bridge circuits 302, 304, etc.). Each half-bridge circuit is coupled to a battery cell (e.g., battery cells 202, 204, etc.) and an LC circuit (e.g., an instance of LC circuit 306). Each integrated circuit 330 may provide a synchronization signal (labeled SYNC in Figure 13 ) to a successive integrated circuit 330. The synchronization signal enables synchronization of the timing (phasing) of the driver signals generated by the control circuit 308 of each integrated circuit 330. The battery manager circuit 208 may be coupled to each battery cell and to each integrated circuit 330 for measuring battery cell parameters and transmitting cell balancing parameters. Thus, the active cell balancing circuit 206 may set the phase of the driver signals generated in each integrated circuit 330 to transfer charge between batteries coupled to different instances of the integrated circuit 330.

[0084] Figure 14 is a schematic diagram of an example active cell balancing circuit that includes a disconnect switch coupled between LC circuits. In Figure 14 , the active cell balancing circuit includes half-bridge circuits 1400 and 1402, and a transistor 1404. In some instances, the active cell balancing circuit may include more than two half-bridge circuits. The half-bridge circuits 1400 and 1402 may be the same as the half-bridge circuit 302. The LC circuits 1406 and 1408 may be the same as the LC circuit 306. The transistor 1404 is coupled between the switching node of the half-bridge circuit 1400 and the capacitor terminal of the active cell balancing circuit. For example, the first current terminal (e.g., source) of the transistor 1404 is coupled to the first capacitor terminal of the active cell balancing circuit, and the second current terminal (e.g., drain) of the transistor 1404 is coupled to the switching node of the half-bridge circuit 1400. The LC circuit 1408 is coupled between the transistor 1404 and the switching node of the half-bridge circuit 1402. The LC circuit 1406 is coupled to the transistor 1404 and the switching node of the half-bridge circuit 1400. The active cell balancing circuit may include any number of instances of the transistor 1404. For example, the active cell balancing circuit may include one instance of the transistor 1404 coupled to the switching node of each half-bridge circuit, or one instance of the transistor 1404 coupled to the switching node of every second half-bridge circuit, or one instance of the transistor 1404 coupled to the switching node of every fourth half-bridge circuit, every tenth half-bridge circuit, etc. The half-bridge circuits, the transistor 1404, and the control circuit 308 may be included in the integrated circuit 330.

[0085] The transistor 1404 may be configured as a unidirectional switch or a bidirectional switch. In some instances, the transistor 1404 allows reduction of the number of half-bridge circuits that switch during charge transfer. For example, in Figure 10AIn [the circuit], even if no charge is transferred to battery cells 908, 910, and 912, the half-bridge circuits 916, 918, and 920 still switch. In an example of an active balancing circuit including transistor 1404 between half-bridge circuit 914 and half-bridge circuit 916, transistor 1404 can be turned off, and the half-bridge circuits 916, 918, and 920 do not need to switch. The control circuit 308 includes an output coupled to the control terminal of transistor 1404. The control circuit 308 provides a control signal C based on AB_CTL D to control the turning on and off of transistor 1404.

[0086] In some examples, transistor 1404 can be coupled between the switching node of a half-bridge circuit and an LC circuit. For example, the first current terminal of transistor 1404 can be coupled to the switching node of 1400, and the second current terminal of transistor 1404 can be coupled to both LC circuits 1406 and 1408 (e.g., the second current terminal of transistor 1404 can be coupled to the connection point of LC circuits 1406 and 1408). In such examples, an instance of transistor 1404 can be coupled to the switching node of each half-bridge circuit. The transistor 1404 of a selected half-bridge circuit can be turned off, and multiple transistors of the selected half-bridge circuit can be turned off, such that charge transfer can occur between the half-bridge circuits on both sides of the selected half-bridge circuit while the selected half-bridge circuit remains idle (not switching).

[0087] Figure 15 is a schematic diagram of an example active cell balancing circuit configured for two-phase operation. In Figure 15 the active cell balancing circuit, half-bridge circuits 302 and 304 and LC circuits 306 and 1508 are configured to operate in a first phase (e.g., transfer charge between battery cells 202 and 204). Half-bridge circuits 1502 and 1504 and LC circuits 1506 and 1508 are configured to operate in a second phase (e.g., transfer charge between battery cells 202 and 204). Half-bridge circuits 302 and 1502 are coupled in parallel to battery cell 202. Half-bridge circuits 304 and 1504 are coupled in parallel to battery cell 204. The active cell balancing circuit can include any number of half-bridge circuits coupled in series in each phase. Half-bridge circuits 1502 and 1504 can be the same as half-bridge circuit 302, and LC circuits 1506, 1508, and 1510 can be the same as LC circuit 306.

[0088] The control circuit 308 is coupled to the half-bridge circuits 302, 304, 1502, and 1504 and generates drive signals C1, C1, C2, C2, C1', C1', C2', and C2' for controlling the switches of the half-bridge circuits. The switches of the half-bridge circuits 1502 and 1504 can be 180° out of phase with the switches of the half-bridge circuits 302 and 304, respectively. The half-bridge circuits and the control circuit 308 can be incorporated into the integrated circuit 330.

[0089] Two-phase operation reduces the current stress on the transistors of the half-bridge circuit, reduces the dc current ripple, and increases the circuit area only slightly compared to a single-phase implementation. Although Figure 15 not shown, the active balancing circuit can include the input filter circuit 506 or the input filter circuit 606. Since the operating phases of the two phases are 180° out of phase, two-phase operation can reduce the AC component in the current flowing through the input filter.

[0090] Figure 16 is a flowchart of an example method 1600 for active cell balancing. Although depicted sequentially for convenience, at least some of the actions shown can be performed in a different order and / or in parallel. Additionally, some implementations may perform only some of the actions shown. The operations of the method 1600 can be performed by an example of the active cell balancing circuit 206.

[0091] In block 1602, the capacitor 320 and the inductor 318 are connected between the first terminal (e.g., the positive terminal) and the second terminal (e.g., the negative terminal) of the battery cell 202 by turning on the transistors 310 and 314. Connecting the capacitor 320 and the inductor 318 between the first and second battery terminals of the battery cell 202 provides a first voltage (e.g., the voltage v1 of the battery cell 202) across the capacitor 320. The capacitor terminal of the capacitor 320 is coupled to the first terminal of the battery cell 202 through the transistor 314, and the inductor terminal of the inductor 318 is coupled to the second terminal of the battery cell 202 through the transistor 310. The operation of block 1602 can be performed during Figure 4 the interval 402.

[0092] In block 1604, the inductor terminal is disconnected from the second battery terminal of the battery cell 202 by turning off the transistor 310. The operation of block 1604 can be performed during Figure 4 the interval 404.

[0093] In block 1606, the inductor terminal is connected to the first battery terminal of the battery cell 202 by turning on the transistor 312, and the voltage across the capacitor 320 is provided across the inductor 318. The operation of block 1606 can be performed during Figure 4during interval 406.

[0094] In block 1608, the capacitor terminal is disconnected from the first battery terminal of battery cell 202 by turning off transistor 314. The operation of block 1608 can be performed during Figure 4 interval 408.

[0095] In block 1610, the capacitor terminal is connected to the battery terminal (e.g., the positive terminal) of battery cell 204 by turning on transistor 316. Connecting the capacitor terminal to the third battery terminal of battery cell 204 transfers the charge from capacitor 320 (e.g., the charge from battery cell 202 stored on capacitor 320 in block 1602) to battery cell 204. The charge transfer rate can be based on the first voltage and the inductance of inductor 318. The operation of block 1610 can be performed during Figure 4 interval 410.

[0096] In method 1600, control circuit 308 can determine a delay interval and apply the delay interval relative to the connection of the inductor terminal to the first battery terminal to connect the capacitor terminal to the third battery terminal. The delay interval can be determined based on the target amount of charge to be transferred from battery cell 202 to battery cell 204.

[0097] Figure 17 is a schematic diagram of another active cell balancing circuit 1706. The active cell balancing circuit 1706 includes half-bridge circuits 302, 304, 502, and 504 respectively coupled to battery cells 202, 204, 508, and 510. Examples of the active cell balancing circuit 1706 can include any number of half-bridge circuits coupled in series. The half-bridge circuits can be included in integrated circuit 330. The active cell balancing circuit 1706 is similar to the active cell balancing circuit 206, but the arrangement of the inductors in the active cell balancing circuit 1706 is different from the arrangement of the inductors in the active cell balancing circuit 206. In the active cell balancing circuit 206, the inductor and the capacitor are in series. In the active cell balancing circuit 1706, the capacitors are in series, and the inductor is coupled between the switching node of the half-bridge circuit and the series capacitors. Thus, in the active cell balancing circuit 1706, the path between two half-bridge circuits separated by any number of battery cells and half-bridge circuits can include only capacitors and two inductors. This arrangement can reduce the losses caused by the inductors and facilitate power transfer over longer distances (e.g., between battery cells separated by a large number of battery cells). In some examples, the inductors used in the active cell balancing circuit 1706 can have half the inductance of the inductors used in the active cell balancing circuit 206. Although Figure 17Although not shown in the figure, the active cell balancing circuit 1706 may further include an input filter circuit 506 or an input filter circuit 606.

[0098] Inductors are coupled to the switching nodes of each half - bridge circuit. The first terminal of inductor 1702 is coupled to the switching node of half - bridge circuit 302. The first terminal of inductor 1705 is coupled to the switching node of half - bridge circuit 304. The first terminal of inductor 1710 is coupled to the switching node of half - bridge circuit 502. The first terminal of inductor 1714 is coupled to the switching node of 510. Capacitors are coupled between inductors that are coupled to the switching nodes of successive half - bridge circuits. Capacitor 1704 is coupled between the second terminal of inductor 1702 and the second terminal of inductor 1705. Capacitor 1708 is coupled between the second terminal of inductor 1705 and the second terminal of inductor 1710. Capacitor 1712 is coupled between the second terminal of inductor 1710 and the second terminal of another inductor (e.g., inductor 1714).

[0099] The control circuit 308 is coupled to half - bridge circuits 302, 304, 502, and 504. The control circuit 308 generates drive signals for controlling the switches in the half - bridge circuits. The half - bridge switches for transferring charge between two batteries can be the same as Figure 4 those described in. In the active cell balancing circuit 206 (e.g., as Figure 5 shown), when charge is to be transferred between any two battery cells, the control circuit 308 causes all the half - bridge circuits to switch (see, for example, Figure 10A and 10B ). In the active cell balancing circuit 1706, since only two inductors are in series between a pair of half - bridge circuits, only the half - bridge circuit for transferring charge needs to be switched, and the intermediate half - bridge between this pair does not need to be switched. For example, to transfer charge from battery cell 202 to battery cell 508, the control circuit 308 can cause half - bridge circuit 302 and half - bridge circuit 502 to switch according to Figure 4 the timing of, and half - bridge circuit 304, half - bridge circuit 504, and any other half - bridge circuits of the active cell balancing circuit 1706 do not switch. As discussed above with respect to Figure 9A , the intermediate half - bridge can be switched (and the switches are phase - shifted equally) to reduce the total inductance along the current path between a pair of half - bridges participating in charge transfer. By limiting the number of inductors between any pair of half - bridge active cell balancing circuits 1706 to two, this arrangement can be omitted.

[0100] Figure 18A and 18B illustrate examples of using the active cell balancing circuit 1706 to transfer charge between different pairs of battery cells in a battery module. InFigure 18A In [description], the battery module includes battery cells 202, 204, 906, 908, 910, and 912 coupled to half - bridge circuits 302, 304, 914, 916, 918, and 920. The half - bridge circuits 914, 916, 918, and 920 may be the same as the half - bridge circuit 302. One of the inductors 1702, 1705, 1710, 1716, 1720, or 1714 is coupled to the switching node of each half - bridge circuit, and one of the capacitors 1704, 1708, 1712, 1718, or 1722 is coupled between adjacent inductors. In Figure 18A In [description], charge is transferred from battery cell 204 to battery cell 202, and from battery cell 910 to battery cell 912. Multiple charge transfers may occur simultaneously. Figure 18B Illustrate the switches in the half - bridge circuits 302, 304, 918, and 920 (e.g., the control circuit 308 provides drive signals to the half - bridge circuits 302, 304, 914, 916, 918, and 920). The switches in the half - bridge circuit 302 are delayed (phase - shifted) relative to the switches in the half - bridge circuit 304. The switches in the half - bridge circuit 920 are delayed (phase - shifted) relative to the switches in the half - bridge circuit 918. The switches in the half - bridge circuit 918 may be in the same phase as the switches in the half - bridge circuit 304. The half - bridge circuits 914 and 916 are idle (no switching occurs). With this switching, charge is transferred from battery cell 204 to battery cell 202, and from battery cell 910 to battery cell 912. No charge is transferred to or from battery cell 906 or battery cell 908. In some instances, the half - bridge circuits coupled to sinking battery cells may switch in - phase, and the phase shift applied to the half - bridge circuits coupled to sourcing battery cells may be adjusted to transfer charge.

[0101] In the active cell - balancing circuit 1706, as the number of capacitors serially coupled between the sourcing half - bridge circuit and the sinking half - bridge circuit increases, the capacitance decreases, and the resonant frequency of the LC network formed by the inductor and the capacitor increases. In some instances, the control circuit 308 may switch the half - bridge circuits at a fixed switching frequency. If the switching frequency is higher than the resonant frequency of the LC network, the active cell - balancing circuit 1706 transfers power. Thus, the number of capacitors serially coupled between the sourcing half - bridge circuit and the sinking half - bridge circuit can be limited such that the switching frequency can be kept higher than the resonant frequency of the LC network.

[0102] Figure 19 Is a schematic diagram of an active cell - balancing circuit that includes a disconnect switch coupled between capacitors. The disconnect switch can be opened to reduce the number of serially - coupled capacitors. Figure 19The half-bridge circuits and disconnect switches are similar to those Figure 14 shown. In Figure 19 , the active cell balancing circuit includes half-bridge circuits 1400 and 1402, inductors 1902 and 1906, capacitors 1904 and 1908, and transistor 1404. In some examples, the active cell balancing circuit may include more than two half-bridge circuits. The first terminal of inductor 1902 is coupled to the switching node of half-bridge circuit 1402, and the first terminal of inductor 1906 is coupled to the switching node of half-bridge circuit 1400. Transistor 1404 is coupled between the second terminal of inductor 1906 and capacitor 1904. Capacitor 1904 is coupled between transistor 1404 and the second terminal of inductor 1902. Capacitor 1908 is coupled to the second terminal of inductor 1906.

[0103] The active cell balancing circuit may include any number of instances of transistor 1404. For example, the active cell balancing circuit may include one instance of transistor 1404 for each half-bridge circuit, or one instance of transistor 1404 for every second half-bridge circuit, or one instance of transistor 1404 for every fourth half-bridge circuit, every tenth half-bridge circuit, etc. The half-bridge circuits, transistor 1404, and control circuit 308 may be included in integrated circuit 330.

[0104] Control circuit 308 includes an output coupled to the control terminal of transistor 1404. Control circuit 308 provides control signal C D based on AB_CTL to control the turning on and off of transistor 1404. Transistor 1404 allows the number of several series-coupled capacitors (e.g., capacitors 1904 and 1908) to be controlled.

[0105] In some examples, half-bridge 1400 may be a first set of M half-bridges coupled together by M-1 instances of capacitors, and half-bridge 1402 may be another set of M half-bridges coupled by M-1 instances of capacitors, similar to Figure 18A shown. By enabling or disabling transistor 1404, the total number of capacitors in the current conduction path between a pair of half-bridges experiencing charge transfer can be limited to M-1, which can set an upper limit on the resonant frequency to be lower than the switching frequency. Additionally, if no charge is to be transferred between the first set of M half-bridges and the second set of M half-bridges, transistor 1404 can be disabled, which can avoid switching all the intermediate half-bridges between the first set of M half-bridges and the second set of M half-bridges.

[0106] Figure 20 is a block diagram of an example of active cell balancing circuit 1706 that includes parallel capacitor network 2002. In Figure 20In it, the active cell balancing circuit 1706 includes n half-bridge circuits 2004 and inductors 2006 coupled to the switching nodes of each half-bridge circuit. The parallel capacitor network 2002 includes a first group of capacitors 2008, a second group of capacitors 2010, a third group of capacitors 2012, and a fourth group of capacitors 2014. The first group of capacitors 2008 is coupled to the inductor as shown in Figure 17 . The first group of capacitors 2008 may include capacitors for each half-bridge circuit. The second group of capacitors 2010 is coupled in parallel with the first group of capacitors 2008. The second group of capacitors 2010 may include capacitors coupled in parallel with m capacitors in the first group of capacitors 2008. The third group of capacitors 2012 is coupled in parallel with the second group of capacitors 2010 and the first group of capacitors 2008. The third group of capacitors 2012 may include capacitors coupled in parallel with 2m capacitors in the first group of capacitors 2008. The fourth group of capacitors 2014 may include capacitors coupled in parallel with n capacitors in the first group of capacitors 2008. Other examples of the parallel capacitor network 2002 may include different numbers of parallel capacitor tiers, and the capacitors in each tier may span different numbers of capacitors in the first group of capacitors 2008.

[0107] The parallel capacitor network 2002 increases the capacitance between two half-bridge circuits, which reduces the resonant frequency of the LC network formed by the parallel capacitor network 2002 and the inductor 2006, and enables power transfer between half-bridge circuits that may be separated by too small a capacitance using only the first group of capacitors 2008.

[0108] Figure 21 is a schematic diagram of an example active cell balancing circuit configured for two-phase operation. Figure 21 The active cell balancing circuit of Figure 15 is similar to the active cell balancing circuit of Figure 21 , but uses the LC arrangement of the active cell balancing circuit 1706 instead of the LC arrangement of the LC circuit 306. In the active cell balancing circuit of Figure 21 , the half-bridge circuits 302 and 304, the inductors 1702 and 1705, and the capacitors 1704 and 1708 are configured to function as the first phase. The half-bridge circuits 1502 and 1504, the inductors 2102 and 2106, and the capacitors 2104 and 2108 are configured to function as the second phase. The half-bridge circuits 302 and 1502 are coupled in parallel with the battery cell 202. The half-bridge circuits 304 and 1504 are coupled in parallel with the battery cell 204. The active cell balancing circuit may include any number of half-bridge circuits coupled in series in each phase. In Figure 21 , an input filter circuit 506 is also shown. Some examples may include an input filter circuit 606 instead of the input filter circuit 506.

[0109] The control circuit 308 is coupled to the half-bridge circuits 302, 304, 1502, and 1504 and generates drive signals C1, C1, C2, C2, C1', C1', C2', and C2' for controlling the switches of the half-bridge circuits. The switches of the half-bridge circuits 1502 and 1504 can be 180° out of phase with the switches of the half-bridge circuits 302 and 304. The half-bridge circuits and the control circuit 308 can be incorporated into the integrated circuit 330.

[0110] Two-phase operation reduces the current stress on the transistors of the half-bridge circuit and increases the circuit area only slightly compared to a single-phase implementation. Since the operating phases of the two phases are 180° out of phase, two-phase operation can reduce the AC component of the current flowing in the input filter.

[0111] Figure 22 is a schematic diagram of another example active cell balancing circuit 2206. The active cell balancing circuit 2206 includes half-bridge circuits 302, 304, 502, and 504 respectively coupled to battery cells 202, 204, 508, and 510. Examples of the active cell balancing circuit 2206 can include any number of half-bridge circuits coupled in series. The half-bridge circuits can be included in the integrated circuit 330. The active cell balancing circuit 2206 is similar to the active cell balancing circuit 1706, but the inductors and capacitors have been swapped relative to the active cell balancing circuit 1706. In the active cell balancing circuit 2206, the inductors are coupled in series, and the capacitors are coupled between the switching nodes of the half-bridge circuits and the series inductors. Thus, in the active cell balancing circuit 2206, the path between the two half-bridge circuits includes only inductors and two capacitors, which can reduce the capacitance reduction caused by the series-coupled capacitors and the resulting increase in the resonant frequency. The active cell balancing circuit 2206 can also include an input filter circuit 506 or an input filter circuit 606. In Figure 22 is shown an active cell balancing circuit 2206 including an input filter circuit 506.

[0112] In the active cell balancing circuit 2206, capacitors are coupled to the switching nodes of each half - bridge circuit. The first terminal of capacitor 2202 is coupled to the switching node of half - bridge circuit 302. The first terminal of capacitor 2205 is coupled to the switching node of half - bridge circuit 304. The first terminal of capacitor 2210 is coupled to the switching node of half - bridge circuit 502. The first terminal of capacitor 2214 is coupled to the switching node of 510. Inductors are coupled between capacitors that are coupled to the switching nodes of successive half - bridge circuits. Inductor 2204 is coupled between the second terminal of 2202 and the second terminal of capacitor 2205. Inductor 2208 is coupled between the second terminal of capacitor 2205 and the second terminal of 2210. Inductor 2212 is coupled between the second terminal of 2210 and the second terminal of another capacitor (e.g., capacitor 2214).

[0113] The control circuit 308 is coupled to half - bridge circuits 302, 304, 502, and 504. The control circuit 308 generates drive signals for controlling the switches in the half - bridge circuits. The half - bridge switches for transferring charge between two batteries can be the same as Figure 4 those described in. In the active cell balancing circuit 2206, as in the active cell balancing circuit 206, when charge is to be transferred between any two battery cells, the control circuit 308 causes all of the half - bridge circuits to switch (see, for example Figure 9A / 9B, 10A / 10B, 11A / 11B, and 12A / 12B).

[0114] Figure 23 is a schematic diagram of an example of the active cell balancing circuit 2206 that includes disconnect switches. The disconnect switches can be opened to reduce the number of inductors coupled in series. Figure 23 The half - bridge circuits and disconnect switches of Figure 14 are similar to those shown in Figure 23 In, the active cell balancing circuit includes half - bridge circuits 1400 and 1402, capacitors 2302 and 2306, inductors 2304 and 2308, and transistor 1404. In some examples, the active cell balancing circuit can include more than two half - bridge circuits, capacitors, and inductors. The first terminal of capacitor 2302 is coupled to the switching node of half - bridge circuit 1402, and the first terminal of capacitor 2306 is coupled to the switching node of half - bridge circuit 1400. Transistor 1404 is coupled between the second terminal of capacitor 2306 and inductor 2304. Inductor 2304 is coupled between transistor 1404 and the second terminal of capacitor 2302. Inductor 2308 is coupled to the second terminal of capacitor 2306.

[0115] The active cell balancing circuit can include any number of instances of transistor 1404. For example, the active cell balancing circuit can include one instance of transistor 1404 for each half - bridge circuit (between each pair of adjacent half - bridge circuits), or one instance of transistor 1404 for every second half - bridge circuit, or one instance of transistor 1404 for every fourth half - bridge circuit, every tenth half - bridge circuit, etc. The half - bridge circuits, transistor 1404, and control circuit 308 can be included in integrated circuit 330.

[0116] Control circuit 308 includes an output coupled to the control terminal of transistor 1404. Control circuit 308 provides control signal C based on AB_CTL D to control the turning on and off of transistor 1404. In some instances, transistor 1404 allows controlling the number of several inductors (e.g., inductors 2304 and 2308) connected in series, and reduces the number of half - bridge circuits where switching occurs during charge transfer, as illustrated in reference Figure 14 as explained.

[0117] Figure 24 is a schematic diagram of an active cell balancing circuit configured for two - phase operation based on active cell balancing circuit 2206. Figure 24 The active cell balancing circuit of Figure 15 is similar to the active cell balancing circuit of Figure 24 but uses the LC arrangement of active cell balancing circuit 2206 instead of the LC arrangement of active cell balancing circuit 206. In the active cell balancing circuit of Figure 24 , input filter circuit 506 is also shown. Some instances can include input filter circuit 606 instead of input filter circuit 506.

[0118] Control circuit 308 is coupled to half - bridge circuits 302, 304, 1502, and 1504, and generates drive signals C1, C1, C2, C2, C1', C1', C2', and C2' to control the switches of the half - bridge circuits. Control circuit 308 can generate drive signals such that the switches of half - bridge circuits 1502 and 1504 can be 180° out of phase with the switches of half - bridge circuits 302 and 304. The half - bridge circuits and control circuit 308 can be incorporated into integrated circuit 330.

[0119] The two-phase operation reduces the current stress on the transistors of the half-bridge circuit and increases the circuit area only slightly compared to the single-phase implementation. Since the operating phases of the two phases are 180° out of phase, the two-phase operation can reduce the AC component of the current flowing in the input filter.

[0120] Figure 25 FIG. 6 is a schematic diagram of another example active cell balancing circuit 2506. The active cell balancing circuit 2506 includes half-bridge circuits 302, 304, 502, and 504 respectively coupled to battery cells 202, 204, 508, and 510. Examples of the active cell balancing circuit 2506 may include any number of half-bridge circuits coupled in series. The half-bridge circuits may be included in an integrated circuit 330. The active cell balancing circuit 2506 is similar to the active cell balancing circuit 2206, but in the active cell balancing circuit 2506, an inductor and a capacitor are serially coupled to the switching node of the half-bridge circuit. Thus, in the active cell balancing circuit 2506, the path between the two half-bridge circuits may include only two inductors and two capacitors. The active cell balancing circuit 2506 may also include an input filter circuit 506 or an input filter circuit 606. In Figure 25 FIG. 7, an active cell balancing circuit 2506 including an input filter circuit 506 is shown.

[0121] Capacitors are coupled to the switching nodes of each half-bridge circuit. The first terminal of capacitor 2202 is coupled to the switching node of half-bridge circuit 302. The first terminal of capacitor 2205 is coupled to the switching node of half-bridge circuit 304. The first terminal of capacitor 2210 is coupled to the switching node of half-bridge circuit 502. The first terminal of capacitor 2214 is coupled to the switching node of 510.

[0122] Inductors are serially coupled to each capacitor. The first terminal of inductor 2504 is coupled to the second terminal of capacitor 2202. The first terminal of inductor 2508 is coupled to the second terminal of capacitor 2205. The first terminal of inductor 2512 is coupled to the second terminal of capacitor 2210. The first terminal of inductor 2516 is coupled to the second terminal of capacitor 2214. The second terminal of inductor 2504 is coupled to the second terminals of inductor 2508, inductor 2512, and inductor 2516.

[0123] The control circuit 308 is coupled to the half-bridge circuits 302, 304, 502, and 504. The control circuit 308 generates drive signals for controlling the switches in the half-bridge circuits. The half-bridge switches for transferring charge between two batteries may be associated with Figure 18Ais the same as the half-bridge switch described in / 18B. In the active cell balancing circuit 2506, as in the active cell balancing circuit 1706, when transferring charge between any two battery cells, the control circuit 308 can cause only the source-type half-bridge circuit and the drain-type half-bridge circuit to switch.

[0124] Figure 26 is a schematic diagram of an example of the active cell balancing circuit 2506 that includes a disconnect switch. The disconnect switch can be opened to isolate a selected set of half-bridge circuits. Figure 26 The half-bridge circuits and the disconnect switch of Figure 14 are similar to those half-bridge circuits and disconnect switch shown in Figure 26 In , the active cell balancing circuit includes half-bridge circuits 1400 and 1402, capacitors 2602 and 2606, inductors 2604 and 2608, and a transistor 1404. In some examples, the active cell balancing circuit can include more than two half-bridge circuits. The first terminal of capacitor 2602 is coupled to the switching node of half-bridge circuit 1402, and the first terminal of capacitor 2606 is coupled to the switching node of half-bridge circuit 1400. Inductor 2604 is coupled in series with capacitor 2602, and inductor 2608 is coupled in series with capacitor 2606. The first terminal of 2608 is coupled to the second terminal of 2602, and the first terminal of inductor 2608 is coupled to the second terminal of capacitor 2606. Transistor 1404 is coupled between the second terminal of 2604 and the second terminal of inductor 2608.

[0125] The active cell balancing circuit 2506 can include any number of instances of transistor 1404. For example, the active cell balancing circuit can include one instance of transistor 1404 for each half-bridge circuit (between each pair of adjacent half-bridge circuits), or one instance of transistor 1404 for every second half-bridge circuit, or one instance of transistor 1404 for every fourth half-bridge circuit, every tenth half-bridge circuit, etc. The half-bridge circuits, transistor 1404, and control circuit 308 can be included in the integrated circuit 330.

[0126] The control circuit 308 includes an output coupled to the control terminal of transistor 1404. The control circuit 308 provides a control signal C D based on AB_CTL to control the turning on and off of transistor 1404. Transistor 1404 allows selective control of the number of half-bridge circuits coupled through the LC circuit.

[0127] Figure 27 is a schematic diagram of an active cell balancing circuit configured for two-phase operation based on the active cell balancing circuit 2506. Figure 27 The active cell balancing circuit of Figure 15is similar to the active cell balancing circuit, but uses the LC arrangement of the active cell balancing circuit 2506 instead of the LC arrangement of the active cell balancing circuit 206. In Figure 24 the active cell balancing circuit, the half-bridge circuits 302 and 304, the capacitors 2202 and 2205, and the inductors 2504 and 2508 are configured to act as the first phase. The half-bridge circuits 1502 and 1504, the capacitors 2702 and 2706, and the inductors 2704 and 2708 are configured to act as the second phase. The half-bridge circuits 302 and 1502 are coupled in parallel with the battery cell 202. The half-bridge circuits 304 and 1504 are coupled in parallel with the battery cell 204. The active cell balancing circuit may include any number of half-bridge circuits coupled in series in each phase. In Figure 27 an input filter circuit 506 is also shown. Some examples may include an input filter circuit 606 instead of the input filter circuit 506.

[0128] The control circuit 308 is coupled to the half-bridge circuits 302, 304, 1502, and 1504 and generates drive signals C1, C1, C2, C2, C1', C1', C2', and C2' for controlling the switches of the half-bridge circuits. The control circuit 308 may generate drive signals such that the switches of the half-bridge circuits 1502 and 1504 may be 180° out of phase with the switches of the half-bridge circuits 302 and 304. The half-bridge circuits and the control circuit 308 may be incorporated into an integrated circuit 330.

[0129] The two-phase operation reduces the current stress on the transistors of the half-bridge circuits and increases the circuit area only slightly compared to the single-phase embodiment. Since the operating phases of the two phases are 180° out of phase, the two-phase operation may reduce the AC component of the current flowing in the input filter.

[0130] Figure 28 is a block diagram of a battery assembly 2800 including balanced battery modules across a battery. The battery assembly 2800 includes battery modules 28021 and 28022 to 2802 k . Each battery module includes battery cells and an active cell balancing circuit. The battery module 28021 includes m battery cells 28041 to 2804 m , and each battery cell is coupled to an active cell balancing circuit 28061. The active cell balancing circuit 28061 balances the charge between the battery cells 28041 to 2804 m of the battery module 28021. The battery module 28022 is coupled in series with the battery module 28021 and includes m battery cells 2804 m-1 to 2804 2m , and each battery cell is coupled to an active cell balancing circuit 28062. The active cell balancing circuit 28062 balances the battery cells 2804 of the battery module 28022m+1 charges between and 2804 2m The battery module 2802 k is serially coupled to the battery module 28022 and includes m battery cells 2804 n-m to 2804 n and each battery cell is coupled to an active cell balancing circuit 2806 k The active cell balancing circuit 2806 k balances the battery cells 2804 k of the battery module 2802 n-m to 2804 n The active cell balancing circuits 28061, 28062, and 2806 k can be examples of the active cell balancing circuit 206, the active cell balancing circuit 1706, the active cell balancing circuit 2206, the active cell balancing circuit 2506, or any other active cell balancing circuit described herein.

[0131] The battery assembly 2800 further includes a battery module balancing circuit 2807. The battery module balancing circuit 2807 balances the charges between the battery modules 28021 to 2802 k The battery module balancing circuit 2807 includes half - bridge circuits 28081 and 28082 to 2808 k , a control circuit 2814, components 28101 and 28102 to 2810 k , and components 28121 to 2812 k-1 The half - bridge circuits 28081 and 28082 to 2808 k can be the same as the half - bridge circuit 302 with transistors rated at the battery module voltage. The control circuit 2814 is coupled to the half - bridge circuits 28081 and 28082 to 2808 k The control circuit 2814 generates drive signals S1, S1, S2, S2, SK, and SK for controlling the switches of the half - bridge circuit.

[0132] The components 28101 to 2810 k and the components 28121 to 2812 k-1 can be capacitors, inductors, conductors, or combinations thereof (e.g., series combinations) as described herein. In one example, the components 28101 to 2810 k are conductors, and the components 28121 to 2812 k-1 are examples of the LC circuit 306 as in the active cell balancing circuit 206. In such an example, the control circuit 2814 controls the switches of the half - bridge circuit as described for the active cell balancing circuit 206.

[0133] In another example, components 28101 to 2810 k are inductors, and components 28121 to 2812 k-1 are capacitors, as in the active cell balancing circuit 1706. In this example, the control circuit 2814 controls the switches of the half-bridge circuit as described for the active cell balancing circuit 1706.

[0134] In another example, components 28101 to 2810 k are capacitors, and components 28121 to 2812 k-1 are inductors, as in the active cell balancing circuit 2206. In this example, the control circuit 2814 controls the switches of the half-bridge circuit as described for the active cell balancing circuit 2206.

[0135] In another example, components 28101 to 2810 k are capacitors in series with an inductor, and components 28121 to 2812 k-1 are conductors, as in the active cell balancing circuit 2506. In this example, the control circuit 2814 controls the switches of the half-bridge circuit as described for the active cell balancing circuit 2506.

[0136] Various examples of the battery module balancing circuit 2807 may include switches in series with components 28121 to 2812 k-1 and / or a multiphase circuit system as described herein.

[0137] In this specification, the term "coupled" may encompass a connection, communication, or signal path that achieves a functional relationship consistent with this specification. For example, if device A generates a signal to control device B to perform an action, then: (a) in a first example, device A is coupled to device B by a direct connection; or (b) in a second example, device A is coupled to device B through an intermediate component C, provided that the intermediate component C does not change the functional relationship between device A and device B, such that device B is controlled by device A via the control signal generated by device A.

[0138] Furthermore, in this specification, the recitation of "based on" means "at least partially based on". Thus, if X is based on Y, then X may depend on Y and any number of other factors.

[0139] A device "configured to" perform a task or function may be configured (e.g., programmed and / or hardwired) to perform the function when manufactured by the manufacturer, and / or may be configured (or reconfigured) by the user after manufacture to perform the function and / or other additional or alternative functions. The configuration can be achieved through the firmware and / or software programming of the device, through the construction and / or layout of the hardware components and interconnects of the device, or a combination thereof.

[0140] As used herein, the terms "terminal," "node," "interconnect," "pin," and "lead" are used interchangeably. Unless specifically stated to the contrary, these terms are generally used to denote an interconnect or an end thereof between device elements, circuit elements, integrated circuits, devices, or other electronic devices or semiconductor components.

[0141] A circuit or device described herein as including certain components may actually be adapted to be coupled to those components to form the described circuit system or device. For example, a structure described as including one or more semiconductor elements (e.g., transistors), one or more passive elements (e.g., resistors, capacitors, and / or inductors), and / or one or more sources (e.g., voltage sources and / or current sources) may actually include only semiconductor elements within a single physical device (e.g., a semiconductor die and / or an integrated circuit (IC) package), and may be adapted to be coupled to at least some of the passive elements and / or sources to form the described structure during or after manufacture, e.g., by an end user and / or a third party.

[0142] Although the use of specific transistors is described herein, other transistors (or equivalent devices) may actually be used with little or no change to the rest of the circuit system. For example, field effect transistors ("FETs") (e.g., n-channel FETs (NFETs) or p-channel FETs (PFETs)), bipolar junction transistors (BJTs, e.g., NPN transistors or PNP transistors), insulated gate bipolar transistors (IGBTs), and / or junction field effect transistors (JFETs) may be used in place of or in combination with the devices disclosed herein. The transistors may be depletion-mode devices, drain-extension devices, enhancement-mode devices, native transistors, or other types of device-structure transistors. Additionally, the devices may be implemented in or on a silicon substrate (Si), a silicon carbide substrate (SiC), a gallium nitride substrate (GaN), or a gallium arsenide substrate (GaAs).

[0143] Reference may be made in the claims to the control input of a transistor and its current terminals. In the context of an FET, the control input is the gate, and the current terminals are the drain and source. In the context of a BJT, the control input is the base, and the current terminals are the collector and emitter.

[0144] An FET being "on" as referred to herein means that there is a conductive channel in the FET and drain current can flow through the FET. An FET being "off" as referred to herein means that there is no conductive channel and drain current does not flow through the FET. However, an "off" FET may allow current to flow through the body diode of the transistor.

[0145] The circuits described herein can be reconfigured to include additional or different components to provide functionality that is at least partially similar to the functionality available prior to component replacement. Unless otherwise specified, a component shown as a resistor generally represents any one or more elements coupled in series and / or parallel to provide the amount of impedance represented by the shown resistor. For example, a resistor or capacitor shown and described herein as a single component can alternatively be multiple resistors or capacitors coupled in parallel between the same nodes. For example, a resistor or capacitor shown and described herein as a single component can alternatively be multiple resistors or capacitors coupled in series between the same two nodes as the single resistor or capacitor.

[0146] While some of the elements of the described examples are included in an integrated circuit and other elements are external to the integrated circuit, in other example embodiments, additional or fewer features can be incorporated into the integrated circuit. Additionally, some or all of the features described as being external to the integrated circuit can be included in the integrated circuit, and / or some of the features described as being internal to the integrated circuit can be incorporated external to the integrated circuit. As used herein, the term "integrated circuit" means one or more circuits that: (i) are incorporated in / above a semiconductor substrate; (ii) are incorporated in a single semiconductor package; (iii) are incorporated into the same module; and / or (iv) are incorporated in / on the same printed circuit board.

[0147] Within the scope of the claims, modifications can be made in the described embodiments, and other embodiments are possible.

Claims

1. An integrated circuit (IC) comprising: A first transistor coupled between a first battery terminal and a capacitor terminal, the first transistor having a first transistor control terminal; A second transistor coupled between the capacitor terminal and a second battery terminal, the second transistor having a second transistor control terminal; A third transistor coupled between a third battery terminal and an inductor terminal, the third transistor having a third transistor control terminal, the third battery terminal being coupled to the second battery terminal; And A fourth transistor coupled between the inductor terminal and a fourth battery terminal, the fourth transistor having a fourth transistor control terminal; And A control circuit having a control input and first, second, third, and fourth control outputs, wherein the first control output is coupled to the first transistor control terminal, the second control output is coupled to the second transistor control terminal, the third control output is coupled to the third transistor control terminal, and the fourth control output is coupled to the fourth transistor control terminal.

2. The IC of claim 1, wherein the control circuit is configured to, in response to a control signal: During a first part of a first switching cycle, provide a first driver signal having a first state at the first control output and provide a second driver signal having a second state at the second control output; During a second part of the first switching cycle, provide the first driver signal having the second state at the first control output and provide the second driver signal having the first state at the second control output; During a first part of a second switching cycle, provide a third driver signal having a first state at the third control output and provide a fourth driver signal having a second state at the fourth control output; During a second part of the second switching cycle, provide the third driver signal having the second state at the third control output and provide the fourth driver signal having the first state at the fourth control output; And Wherein: The first transistor is enabled in response to the first driver signal having the first state and disabled in response to the first driver signal having the second state; The second transistor is enabled in response to the second driver signal having the first state and disabled in response to the second driver signal having the second state; The third transistor is enabled in response to the third driver signal having the first state and disabled in response to the third driver signal having the second state; and The fourth transistor is disabled in response to the fourth driver signal having the second state and enabled in response to the fourth driver signal having the first state.

3. The IC according to claim 2, wherein the control circuit is configured to, in response to the control signal indicating charge transfer between the first battery terminal and the third battery terminal and between the second battery terminal and the fourth battery terminal, set an interval between a first transition of the first driver signal from the second state to the first state and a second transition of the third driver signal from the second state to the first state, wherein the interval is based on the amount of current to be transferred.

4. The IC according to claim 3, wherein the control circuit is configured to, in response to the control signal indicating the charge transfer from the third battery terminal to the first battery terminal and from the fourth battery terminal to the second battery terminal, provide the second transition of the third driver signal at the interval before the first transition of the first driver signal.

5. The IC according to claim 3, wherein the control circuit is configured to, in response to the control signal indicating the charge transfer from the first battery terminal to the third battery terminal and from the second battery terminal to the fourth battery terminal, provide the second transition of the third driver signal at the interval after the first transition of the first driver signal.

6. The IC according to claim 3, wherein the interval is based on at least one of the following: a voltage difference between the first battery terminal and the third battery terminal, or an inductance of an inductor coupled to the inductor terminal.

7. The IC according to claim 3, wherein the control circuit is configured to: provide the first driver signal and the second driver signal having the second state within a first dead time interval and a second dead time interval of the first switching cycle, wherein the first dead time interval is before the first part of the first switching cycle, and the second dead time interval is after the first part of the first switching cycle; and provide the third driver signal and the fourth driver signal having the second state within a third dead time interval and a fourth dead time interval of the second switching cycle, wherein the third dead time interval is before the first part of the second switching cycle, and the fourth dead time interval is after the first part of the second switching cycle.

8. The IC according to claim 2, wherein the inductor terminal is a first inductor terminal, the capacitor terminal is a first capacitor terminal, the fourth transistor is coupled between a second capacitor terminal and the fourth battery terminal, the second capacitor terminal is coupled to the first inductor terminal, and the IC further includes: a fifth transistor coupled between a fifth battery terminal and a second inductor terminal, the fifth transistor having a fifth transistor control terminal, wherein the fifth battery terminal is coupled to the fourth battery terminal; and a sixth transistor coupled between the second inductor terminal and a sixth battery terminal, the sixth transistor having a sixth transistor control terminal; The control circuit has a fifth control output and a sixth control output, where the fifth control output is coupled to the fifth transistor control terminal, the sixth control output is coupled to the sixth transistor control terminal, and the control circuit is configured to respond to the control signal: within a first part of a third switching cycle, provide a fifth driver signal having a first state at the fifth control output and provide a sixth driver signal having a second state at the sixth control output; within a second part of the third switching cycle, provide the fifth driver signal having the second state at the fifth control output and provide the sixth driver signal having the first state at the fifth control output; wherein the fifth transistor is enabled in response to the fifth driver signal having the first state and the fifth transistor is disabled in response to the fifth driver signal having the second state; and wherein the sixth transistor is enabled in response to the sixth driver signal having the first state and the sixth transistor is disabled in response to the sixth driver signal having the second state.

9. The IC according to claim 8, wherein the control circuit is configured to respond to the control signal indicating charge transfer between the first battery terminal and the fifth battery terminal and between the second battery terminal and the sixth battery terminal: provide a first transition of the first driver signal from the second state to the first state at a first interval before a second transition of the third driver signal from the second state to the first state; and provide a third transition of the fifth driver signal from the second state to the first state at a second interval after the second transition of the third driver signal from the second state to the first state, wherein the first interval and the second interval are based on the amount of current to be transferred.

10. The IC according to claim 9, wherein the first interval and the second interval are equal.

11. The IC according to claim 8, wherein the control circuit is configured to respond to the control signal indicating charge transfer from the first battery terminal to the fifth battery terminal and from the second battery terminal to the sixth battery terminal: provide a first transition of the first driver signal from the second state to the first state at an interval before a second transition of the fifth driver signal from the second state to the first state, wherein the interval is based on the amount of current to be transferred; and set the third driver signal and the fourth driver signal to the second state within the interval.

12. The IC according to claim 8, further comprising: a seventh transistor coupled between a seventh battery terminal and a third inductor terminal, the seventh transistor having a seventh transistor control terminal, wherein the seventh battery terminal is coupled to the sixth battery terminal; and An eighth transistor, coupled between the third inductor terminal and the eighth battery terminal, the eighth transistor having an eighth transistor control terminal; wherein the control circuit has a seventh control output and an eighth control output, wherein the seventh control output is coupled to the seventh transistor control terminal, the eighth control output is coupled to the eighth transistor control terminal, and the control circuit is configured to respond to the control signal: within a first portion of a fourth switching cycle, provide a seventh driver signal having a first state at the seventh control output and provide an eighth driver signal having a second state at the eighth control output; within a second portion of the fourth switching cycle, provide the seventh driver signal having the second state at the seventh control output and provide the eighth driver signal having the first state at the eighth control output; wherein the seventh transistor is enabled in response to the seventh driver signal having the first state and the seventh transistor is disabled in response to the seventh driver signal having the second state; and wherein the eighth transistor is enabled in response to the eighth driver signal having the first state and the eighth transistor is disabled in response to the eighth driver signal having the second state.

13. The IC according to claim 12, wherein the control circuit is configured to in response to the control signal indicating a first charge transfer between the first battery terminal and the third battery terminal and between the second battery terminal and the fourth battery terminal and a second charge transfer between the fifth battery terminal and the seventh battery terminal and between the sixth battery terminal and the eighth battery terminal: set an interval between a first transition of the first driver signal from the second state to the first state and a second transition of the third driver signal from the second state to the first state, wherein the interval is based on the amount of current to be transferred; and set an interval between a first transition of the fifth driver signal from the second state to the first state and a second transition of the seventh driver signal from the second state to the first state, wherein the interval is based on the amount of current to be transferred.

14. The IC according to claim 2, further comprising: a fifth transistor, coupled between the capacitor terminal and the first transistor and the second transistor, the fifth transistor having a fifth transistor control terminal; wherein the control circuit has a fifth control output coupled to the fifth transistor control terminal.

15. A method, comprising: connecting a capacitor and an inductor between a first battery terminal and a second battery terminal of a first battery cell to provide a first voltage across the capacitor, wherein the capacitor terminal of the capacitor is connected to the first battery terminal and the inductor terminal of the inductor is connected to the second battery terminal; disconnecting the inductor terminal from the second battery terminal; Connect the inductor terminal to the first battery terminal to provide the first voltage across the inductor; Disconnect the capacitor terminal from the first battery terminal; And Connect the capacitor terminal to the third battery terminal of the second battery cell so as to transfer charge from the capacitor to the second battery cell at a rate based on the first voltage and the inductance of the inductor.

16. The method according to claim 15, further comprising: Determine a delay interval based on a target current amount to be transferred from the first battery cell to the second battery cell; And Delay the connection of the capacitor terminal to the third battery terminal by the delay interval relative to the connection of the inductor terminal to the first battery terminal.

17. A system, comprising: A first battery and a second battery, the first battery having a first battery terminal and a second battery terminal, the second battery having a third battery terminal and a fourth battery terminal, the second battery terminal being coupled to the third battery terminal; An integrated circuit, comprising: A first transistor coupled between the first battery terminal and a capacitor terminal; A second transistor coupled between the capacitor terminal and the second battery terminal, A third transistor coupled between the third battery terminal and an inductor terminal, and A fourth transistor coupled between the inductor terminal and the fourth battery terminal, and A capacitor and an inductor coupled in series, the capacitor being coupled to the capacitor terminal and the inductor being coupled to the inductor terminal.

18. The system according to claim 17, wherein: The first transistor has a first transistor control terminal; The second transistor has a second transistor control terminal; The third transistor has a third transistor control terminal; The fourth transistor has a fourth transistor control terminal; and The integrated circuit comprises a control circuit having a control input and first, second, third, and fourth control outputs, wherein the first control output is coupled to the first transistor control terminal, the second control output is coupled to the second transistor control terminal, the third control output is coupled to the third transistor control terminal, and the fourth control output is coupled to the fourth transistor control terminal.

19. The system according to claim 18, wherein the control circuit is configured to respond to a control signal: During a first part of a first switching cycle, provide a first driver signal having a first state at the first control output and a second driver signal having a second state at the second control output; During a second part of the first switching cycle, provide the first driver signal having the second state at the first control output and the second driver signal having the first state at the second control output; During a first portion of a second switching cycle, a third driver signal having a first state is provided at the third control output, and a fourth driver signal having a second state is provided at the fourth control output; During a second portion of the second switching cycle, the third driver signal having the second state is provided at the third control output, and the fourth driver signal having the first state is provided at the fourth control output; and wherein: the first transistor is enabled in response to the first driver signal having the first state and disabled in response to the first driver signal having the second state; the second transistor is enabled in response to the second driver signal having the first state and disabled in response to the second driver signal having the second state; the third transistor is enabled in response to the third driver signal having the first state and disabled in response to the third driver signal having the second state; and the fourth transistor is disabled in response to the fourth driver signal having the second state and enabled in response to the fourth driver signal having the first state.

20. The system of claim 19, wherein: the inductor terminal is a first inductor terminal, the capacitor terminal is a first capacitor terminal, the fourth transistor is coupled between a second capacitor terminal and the fourth battery terminal, and the second capacitor terminal is coupled to the first inductor terminal; the system includes a third battery having a fifth battery terminal and a sixth battery terminal, the fifth battery terminal being coupled to the fourth battery terminal; the integrated circuit further includes: a fifth transistor coupled between the fifth battery terminal and a second inductor terminal, the fifth transistor having a fifth transistor control terminal; and a sixth transistor coupled between the second inductor terminal and the sixth battery terminal, the sixth transistor having a sixth transistor control terminal; and the control circuit has a fifth control output and a sixth control output, wherein the fifth control output is coupled to the fifth transistor control terminal, the sixth control output is coupled to the sixth transistor control terminal, and the control circuit is configured to respond to the control signal: During a first portion of a third switching cycle, a fifth driver signal having a first state is provided at the fifth control output, and a sixth driver signal having a second state is provided at the sixth control output; During a second portion of the third switching cycle, the fifth driver signal having the second state is provided at the fifth control output, and the sixth driver signal having the first state is provided at the fifth control output; the fifth transistor is enabled in response to the fifth driver signal having the first state and disabled in response to the fifth driver signal having the second state; and The sixth transistor is enabled in response to the sixth driver signal having the first state and disabled in response to the sixth driver signal having the second state.

21. The system of claim 20, wherein the control circuit is configured to respond to the control signal indicating charge transfer from the first battery terminal to the fifth battery terminal and from the second battery terminal to the sixth battery terminal: providing a first transition of the first driver signal from the second state to the first state at a first interval before a second transition of the third driver signal from the second state to the first state; and providing a third transition of the fifth driver signal from the second state to the first state at a second interval after the second transition of the third driver signal from the second state to the first state, wherein the first interval and the second interval are based on the amount of current to be transferred.

22. The system of claim 21, wherein the first interval and the second interval are equal.

23. The system of claim 20, wherein the control circuit is configured to respond to the control signal indicating charge transfer from the first battery terminal to the fifth battery terminal and from the second battery terminal to the sixth battery terminal: providing a first transition of the first driver signal from the second state to the first state at an interval before a second transition of the fifth driver signal from the second state to the first state, wherein the interval is based on the amount of current to be transferred; and setting the third driver signal and the fourth driver signal to the second state within the interval.

24. A battery assembly, comprising: a first battery module including a first module terminal and a second module terminal, and a first battery and a second battery serially coupled between the first module terminal and the second module terminal; a second battery module including a third module terminal and a fourth module terminal, and a third battery and a fourth battery serially coupled between the third module terminal and the fourth module terminal, wherein the third module terminal is coupled to the second module terminal; a first transistor coupled between the first module terminal and a first resonant component terminal, the first transistor having a first transistor control terminal; a second transistor coupled between the first resonant component terminal and the second module terminal, the second transistor having a second transistor control terminal; a third transistor coupled between the third module terminal and a second resonant component terminal, the third transistor having a third transistor control terminal; and a fourth transistor coupled between the second resonant component terminal and the fourth module terminal, the fourth transistor having a fourth transistor control terminal; and a control circuit having a control input and first, second, third, and fourth control outputs, wherein the first control output is coupled to the first transistor control terminal, the second The control output is coupled to the control terminal of the second transistor, the third control output is coupled to the control terminal of the third transistor, and the fourth control output is coupled to the control terminal of the fourth transistor.

25. The battery assembly according to claim 24, further comprising: A capacitor and an inductor, serially coupled between the first resonant component terminal and the second resonant component terminal; Or A first inductor, a capacitor, and a second inductor, serially coupled between the first resonant component terminal and the second resonant component terminal; or A first capacitor, an inductor, and a second capacitor, serially coupled between the first resonant component terminal and the second resonant component terminal; or A first capacitor, a first inductor, a second inductor, and a second capacitor, serially coupled between the first resonant component terminal and the second resonant component terminal.

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