Active cell balancing circuit for a battery pack

Abstract

An active cell balancing circuit (100) for a battery pack (105) including a plurality of battery cells (110) is provided. The active cell balancing circuit includes a plurality of transformers (T1, T2,..., Tn) each having a primary winding and a secondary winding, wherein the secondary winding is coupled to the plurality of battery cells; a plurality of transformer controllers (130) each coupled to the plurality of transformers to provide an input signal to the primary winding; and a balancing controller (115) coupled to the plurality of transformer controllers and the plurality of transformers to detect a current or a voltage at one or more of the primary windings and to output a control signal to cause the transformer controllers to generate the input signal provided to the primary winding. The balancing controller selectively outputs the control signal based on the detected current or voltage to charge one or more of the plurality of battery cells.

Description

Cross-reference to related applications

[0001] This application claims priority to U.S. Nonprovisional Patent Application No. 19 / 061,497, filed February 24, 2025, and U.S. Provisional Patent Application No. 63 / 557,199, filed February 23, 2024, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0002] This disclosure relates in general to balancing cells contained in a battery pack, and more specifically to pack-to-cell active cell balancing in a battery pack. Summary of the Invention

[0003] According to one or more examples, an active cell balancing circuit for a battery pack comprising multiple battery cells is provided. The active cell balancing circuit may include: multiple transformers, each having a primary winding and a secondary winding, wherein the secondary winding is coupled to multiple battery cells; multiple transformer controllers, each coupled to the multiple transformers to provide an input signal to the primary winding; and a balancing controller, coupled to the multiple transformer controllers and the multiple transformers, to detect current or voltage at one or more of the primary windings and output a control signal to cause the transformer controllers to generate the input signal provided to the primary winding. The balancing controller may selectively output the control signal based on the detected current or voltage to charge one or more of the multiple battery cells. The active cell balancing circuit may include a switching converter coupled to the balancing controller and a first battery cell among the multiple battery cells. The battery cells may be connected in series. The active cell balancing circuit may include multiple reverse current protection circuits, each coupled between a terminal of one of the multiple battery cells and a secondary winding of a transformer, to limit current flow between the battery cells and the transformer. The primary windings of the transformers can be coupled together and can be coupled to a balance controller. The active cell balancing circuit may include multiple overcurrent protection circuits, each coupled between the primary windings of multiple transformers and the balance controller. The transformer controller may be a pulse width modulation (PWM) controller. The balance controller can adjust the control signal based on the voltage level difference between the battery cells. The balance controller can store historical charging data to predict future charging behavior of the battery cells. The active cell balancing circuit may include a temperature sensor coupled to the balance controller to monitor the operating temperature of the battery cells and adjust the control signal accordingly. The transformers may operate in resonant mode to enhance power transfer efficiency. The balance controller may include a diagnostic module for detecting faulty battery cells based on abnormal current or voltage measurements.

[0004] According to one or more examples, an active cell balancing circuit is provided for multiple battery pack modules, each comprising multiple battery cells. The active cell balancing circuit may include: a main switch converter coupled to a first battery pack module among the multiple battery pack modules; multiple main transformers, each having a primary winding and a secondary winding, wherein the secondary windings are coupled to the multiple battery pack modules to provide corresponding supply voltages; a power output circuit coupled to the primary winding of the main transformers; multiple rectifier circuits coupled to the secondary windings of the main transformers to output rectified supply voltages; a main transformer controller coupled to the main transformers to provide a main input signal to the primary windings; and a main balancing controller coupled to the main transformer controller and the main transformers to collect information related to the current or voltage at the primary windings and output a main control signal to control the main transformer controller. The main balancing controller may selectively output the main control signal based on the information to charge one or more battery cells. The main transformer controller may be a pulse width modulation (PWM) controller. The active cell balancing circuit may include a main rectifier circuit for rectifying the supply voltage for distribution to the battery pack modules. The active cell balancing circuit may include multiple overcurrent protection circuits coupled between the primary winding of the main transformer and the power output circuit. The main balancing controller may communicate with the balancing controllers of each battery pack module to synchronize charge balance across multiple modules. The multiple transformers may include isolation transformers for electrically isolating each battery pack module from the power output circuit. The multiple battery cells may include lithium-ion cells arranged in a series configuration. The main balancing controller may implement a pre-programmed charge balancing algorithm based on a predefined voltage threshold for each battery cell. Attached Figure Description

[0005] Figure 1 Block diagrams of active cell balancing circuits for battery packs comprising multiple battery cells are shown, according to various examples.

[0006] Figure 2 An active cell balancing circuit for multiple battery pack modules, each comprising multiple battery cells, is shown according to various examples. Detailed Implementation

[0007] Reference will now be made to the various examples illustrated in the accompanying drawings, in which the same reference numerals always denote the same elements. These examples may be presented in various forms, and are not limited to those described herein.

[0008] Batteries are energy storage devices used to provide energy in a variety of applications, including but not limited to portable electronic devices, automobiles, energy storage systems, solar panels, telecommunications, and large battery power systems. Multiple battery cells can be included in a battery pack to provide energy to a load that varies depending on the application. As the battery pack provides energy to the load, the charge of each individual battery cell can decrease at different rates. If the charge of the individual battery cells remains unbalanced, the capacity of the battery pack may decrease over time. One method of balancing the charge levels of battery cells is called passive balancing, which dissipates the charge of battery cells with charge levels higher than the lowest charge level among the battery cells in the pack. For example, a battery cell can be coupled to a resistor, which dissipates the additional charge as heat. By dissipating the additional charge, the charge levels of multiple cells are reduced to the lowest charge level among the multiple battery cells. While passive balancing can balance the charge levels of battery cells, the additional charge is wasted as heat. Active balancing is more efficient than passive balancing and transfers charge from battery cells with higher charge levels to battery cells with lower charge levels. However, additional circuitry is required to control charge transfer from higher-charge cells to lower-charge cells. Therefore, a circuit is needed to balance the charge of the battery cells in a battery pack in an efficient manner without requiring complex control circuitry.

[0009] Figure 1 A block diagram of an active cell balancing circuit 100 for a battery pack 105 comprising multiple battery cells 110 is shown, according to various examples. Figure 1 The battery pack 105 includes a plurality of (“n”) battery cells 110 having voltages V1, V2, V3, ..., Vn. The plurality of battery cells 110 are coupled in series, with the first battery cell having voltage V1 coupled to a balance controller (BC) 115 via a switch converter (SC) 120. The last battery cell having voltage Vn is also coupled to the balance controller BC 115. The active cell balancing circuit 100 may include a plurality of transformers (T1, T2, T3, ..., Tn) 125 corresponding to the plurality of battery cells 110. The plurality of transformers T1...Tn 125 each have a primary winding and a secondary winding, with the secondary winding of the respective transformer T1...Tn 125 coupled to the corresponding battery cell 110 having voltages V1...Vn. For example, the secondary winding of transformer T1 is coupled to the battery cell having voltage V1, the secondary winding of transformer T2 is coupled to the battery cell having voltage V2, and so on.

[0010] The active cell balancing circuit 100 may include multiple transformer controllers (C1, C2, C3, ..., Cn) 130, which correspond to multiple transformers T1...Tn 125 and are respectively coupled to the primary windings of the multiple transformers T1...Tn 125. The transformer controllers C1...Cn 130 may provide input signals to the primary windings of the multiple transformers T1...Tn 125 respectively to turn the transformers T1...Tn 125 on and off. According to various examples, the transformer controllers C1...Cn 130 may be pulse width modulation (PWM) controllers that control the pulse width of the input signals provided to the primary windings of the multiple transformers T1...Tn 125.

[0011] The balance controller BC 115 can detect the current or voltage at one or more primary windings of multiple transformers T1…Tn 125, and can selectively output control signals to cause multiple transformer controllers C1…Cn 130 to generate output signals respectively provided to turn on or off the primary windings of multiple transformers T1…Tn 125. The input signal provided to the primary windings of one or more transformers T1…Tn 125 generates a voltage in the corresponding secondary winding, which charges the corresponding battery cell coupled to the secondary winding. For example, the balance controller BC 115 can output a control signal to transformer controller C2, which causes transformer controller C2 to generate an input signal to turn on transformer T2. The input signal provided to the primary winding of transformer T2 generates a voltage in the secondary winding of transformer T2, which charges the battery cell with voltage V2. By selectively outputting control signals based on detected current or voltage, the balance controller BC 115 can balance the charge level of battery cell 110 by increasing the charge level of battery cell 110 that has a lower charge level relative to other battery cells 110.

[0012] According to various examples, the active cell balancing circuit 100 may include multiple reverse current protection circuits (RC1, RC2, RC3, ..., RCn) 135, which are respectively coupled between the positive and negative terminals of multiple battery cells 110 and the secondary windings of multiple transformers T1...Tn 125. The reverse current protection circuits RC1...RCn 135 can limit the current flow between the multiple battery cells 110 and the secondary windings of the corresponding transformers. The reverse current protection circuits RC1...RCn 135 can also rectify the voltage generated at the secondary windings of the corresponding transformers T1...Tn 125. According to various examples, the active cell balancing circuit 100 may include multiple overcurrent protection circuits (OC1, OC2, OC3, ..., OCn) 140, which are respectively coupled between the primary windings of multiple transformers T1...Tn 125 and the balancing controller BC 115 to limit the current supplied to the balancing controller BC 115, thereby reducing the chance of damage.

[0013] Figure 2 An active cell balancing circuit 200 for multiple battery pack modules 205, each comprising multiple battery cells 210, is shown according to various examples. Figure 1 An active cell balancing circuit 100 is illustrated for a single battery module 105 having multiple battery cells 110. In contrast, Figure 2 An active cell balancing circuit 200 is shown for multiple battery pack modules 205, each of which includes multiple battery cells 210. Specifically, Figure 2 Includes three battery pack modules 205 (although any number of modules can be used), each of which includes [missing information - likely related to battery pack modules]. Figure 1 The same component described in a single module example. Figure 2 In this designation, the reference numerals for each component have been modified to indicate the module in which they reside. For example, the battery cell 210 of module 2 is indicated as having voltages V2-1, V2-2, V2-3, ..., V2-n. Similarly, the multiple transformers 215 of module 2 are indicated as T2-1, T2-2, T2-3, ..., T2-n. A similar naming convention is used for the multiple transformer controllers (C2-1, C2-2, ..., C2-n) 220, the reverse current protection circuit (RC2-1, RC2-2, ..., RC2-n) 225, the overcurrent protection circuit (OC2-1, OC2-2, ..., OC2-n) 230, the switching converter (SC1, SC2, SC3) 235, and the balance controller (BC1, BC2, BC3) 240. This will not be repeated here. Figure 2 In Figure 1 Detailed discussion of the components shown is omitted to avoid redundancy.

[0014] Figure 2 The active cell balancing circuit 200 includes a main switch converter (MSC) 245 coupled to a first battery pack module 1 among multiple battery pack modules 205. The MSC 245 can be coupled to a switch converter SC1 of module 1 and can regulate the voltage received from SC1 to output a regulated voltage to a power output circuit (PS) 250. The active cell balancing circuit 200 may also include multiple main transformers (MT1, MT2, MT3) 255, each having a secondary winding and a primary winding. The secondary winding is coupled to the multiple battery pack modules 205, and the primary winding is coupled to the power output circuit PS 250 to provide a supply voltage to the battery pack modules 205. The active cell balancing circuit 200 may include multiple rectifier circuits (R1, R2, R3) 260, which are coupled between the secondary windings of the multiple main transformers MT1, MT2, MT3 255 to rectify the corresponding supply voltages. The rectified supply voltage can be provided to the primary windings of multiple transformers T1-1……T1-n, T2-1……T2-n, T3-1……T3-n 215 via the corresponding overcurrent protection circuits (OC1-1……OC1-n, OC2-1……OC2-n, OC31……OC3-n) 230.

[0015] Figure 2 The active cell balancing 200 may include a main transformer controller (MTC) 265, which is coupled to module 3 of multiple battery pack modules 205. The MTC 265 can provide a main input signal to control the power output from the power output circuit PS250 to the multiple main transformers MT1, MT2, MT3 255. According to various examples, the MTC 265 may be a PWM controller that adjusts the pulse width of the supply voltage signal provided to the primary windings of the main transformers MT1, MT2, MT3 255. Additionally, Figure 2The active cell balancing circuit 200 may include a main balancing controller (MBC) 270 coupled to an MTC 265 and multiple main transformers MT1, MT2, and MT3 255 to detect current or voltage at one or more primary windings of the primary windings of the multiple main transformers MT1, MT2, and MT3 255, and output a main control signal to cause the MTC 265 to generate a main input signal, which controls the supply voltage provided by the power output circuit PS 250 to the primary windings of the main transformers MT1, MT2, and MT3 255. The MBC 270 may selectively output the main control signal based on the detected current or voltage at one or more primary windings of the multiple main transformers MT1, MT2, and MT3 255 to charge one or more of the multiple battery cells 210.

[0016] Various examples have been disclosed herein in conjunction with the foregoing description and accompanying drawings. It should be understood that describing and illustrating each combination and sub-combination of these examples literally would be an undue repetition. Therefore, all examples can be combined in any manner or combination, and this specification (including the accompanying drawings) should be construed as constituting a complete written description of all combinations and sub-combinations of the examples described herein, as well as the ways and processes of preparing and using them, and should support the claims for any such combinations or sub-combinations.

[0017] Those skilled in the art will understand that the examples described herein are not limited to those specifically shown and described above. Furthermore, unless the contrary is mentioned above, it should be noted that all figures are not drawn to scale. Various modifications and variations are possible in accordance with the above teachings.

Claims

1. An active cell balancing circuit for a battery pack comprising multiple battery cells, the active cell balancing circuit comprising: Multiple transformers, each having a primary winding and a secondary winding, wherein the secondary windings are coupled to the multiple battery cells; Multiple transformer controllers, each coupled to the multiple transformers to provide input signals to the primary winding; and A balance controller, coupled to the plurality of transformer controllers and the plurality of transformers, detects current or voltage at one or more of the primary windings and outputs a control signal to cause the transformer controllers to generate the input signal supplied to the primary windings. The balance controller is used to selectively output the control signal based on the detected current or voltage to charge one or more of the plurality of battery cells.

2. The active cell balancing circuit according to claim 1, wherein the active cell balancing circuit includes a switch converter coupled to the balance controller and a first battery cell among the plurality of battery cells, wherein the battery cells are connected in series.

3. The active cell balancing circuit according to claim 1, wherein the active cell balancing circuit includes a plurality of reverse current protection circuits, the plurality of reverse current protection circuits being respectively coupled between the terminals of the plurality of battery cells and the secondary winding of the transformer to limit the current flow between the battery cells and the transformer.

4. The active cell balancing circuit according to claim 1, wherein the primary windings of the transformer are coupled together and coupled to the balancing controller.

5. The active cell balancing circuit according to claim 4, wherein the active cell balancing circuit includes a plurality of overcurrent protection circuits, the plurality of overcurrent protection circuits being respectively coupled between the primary windings of the plurality of transformers and the balancing controller.

6. The active cell balancing circuit according to claim 1, wherein the transformer controller is a pulse width modulation (PWM) controller.

7. The active cell balancing circuit according to claim 1, wherein the balancing controller is used to adjust the control signal based on the voltage level difference between the battery cells.

8. The active cell balancing circuit according to claim 1, wherein the balancing controller is used to store historical charging data to predict the future charging behavior of the battery cell.

9. The active cell balancing circuit according to claim 1, wherein the active cell balancing circuit includes a temperature sensor coupled to the balancing controller to monitor the operating temperature of the battery cell and adjust the control signal accordingly.

10. The active cell balancing circuit of claim 1, wherein the transformer is configured to operate in resonant mode to enhance power transmission efficiency.

11. The active cell balancing circuit according to claim 1, wherein the balancing controller includes a diagnostic module for detecting faulty battery cells based on abnormal current or voltage measurements.

12. The active cell balancing circuit according to claim 1, wherein the active cell balancing circuit includes a communication interface, the communication interface being used to send status data from the balancing controller to a remote monitoring system.

13. An active cell balancing circuit for multiple battery pack modules, each comprising multiple battery cells, the active cell balancing circuit comprising: A main switch converter, the main switch converter being coupled to a first battery pack module among the plurality of battery pack modules; Multiple main transformers, each having a primary winding and a secondary winding, wherein the secondary windings are coupled to the multiple battery modules to provide corresponding power supply voltages; A power output circuit, the power output circuit being coupled to the primary winding of the main transformer; Multiple rectifier circuits are respectively coupled to the secondary winding of the main transformer to output rectified supply voltage; A main transformer controller, coupled to the main transformer, to provide a main input signal to the primary winding; and A main balancing controller, coupled to the main transformer controller and the main transformer, collects information related to the current or voltage at the primary winding and outputs a main control signal to control the main transformer controller. The main balance controller is used to selectively output the main control signal based on the information to charge one or more battery cells.

14. The active cell balancing circuit according to claim 13, wherein the main transformer controller is a pulse width modulation (PWM) controller.

15. The active cell balancing circuit according to claim 13, wherein the active cell balancing circuit includes a main rectifier circuit for rectifying the supply voltage for distribution to the battery pack module.

16. The active cell balancing circuit according to claim 13, wherein the active cell balancing circuit includes a plurality of overcurrent protection circuits, the plurality of overcurrent protection circuits being respectively coupled between the primary winding of the main transformer and the power output circuit.

17. The active cell balancing circuit of claim 13, wherein the main balancing controller is configured to communicate with the balancing controllers of each battery pack module to synchronize charge balance across multiple modules.

18. The active cell balancing circuit of claim 13, wherein the plurality of transformers includes an isolation transformer for electrically isolating each battery module from the power output circuit.

19. The active cell balancing circuit of claim 13, wherein the plurality of battery cells comprises lithium-ion cells arranged in a series configuration.

20. The active cell balancing circuit of claim 13, wherein the main balancing controller is used to implement a pre-programmed charge balancing algorithm based on a predefined voltage threshold for each battery cell.

Images