A battery balancing system and an electric vehicle

Abstract

This application relates to the field of battery balancing technology, and provides a battery balancing system and an electric vehicle. The battery balancing system includes N battery packs to be balanced, a magnetic core, N inductor windings, a half-bridge drive circuit, and N switching device groups. Each inductor winding corresponds to one battery pack, and each inductor winding is wound on the magnetic core, with each inductor winding including a center tap. The half-bridge drive circuit is configured to generate an alternating drive signal. The first and second switching devices in the same switching device group are configured to alternately turn on and off under the control of the alternating drive signal. The N inductor windings are magnetically coupled through the magnetic core. The voltage difference between the battery packs drives the current change in each inductor winding, and energy transfer between the battery packs occurs through magnetic coupling. The battery balancing system of this application only requires a magnetic core, inductor windings, a half-bridge drive circuit, and switching device groups to achieve active balancing, reducing costs.

Description

Technical Field

[0001] This application belongs to the field of battery balancing technology, and in particular relates to a battery balancing system and an electric vehicle. Background Technology

[0002] Currently, to reduce energy loss during battery equalization, battery equalization systems typically employ active equalization. However, current active equalization methods are costly because they require a controller for equalization control and an analog front-end chip for acquiring battery data. Summary of the Invention

[0003] In view of this, embodiments of this application provide a battery balancing system and an electric vehicle to solve the technical problem of high cost of active balancing methods in the prior art.

[0004] In a first aspect, embodiments of this application provide a battery balancing system, including N battery packs to be balanced, a magnetic core, N inductor windings, a half-bridge drive circuit, and N groups of switching devices; N is greater than or equal to 2; Each of the inductor windings corresponds to one of the battery packs, and each of the inductor windings is wound on the magnetic core. Each inductor winding includes a center tap. The half-bridge drive circuit is configured to generate alternating drive signals; Each of the switching device groups includes a first switching device and a second switching device, wherein the first switching device and the second switching device in the same switching device group are configured to alternately turn on and off under the control of the alternating drive signal; The positive terminal of each battery pack is connected to the first end of the corresponding inductor winding through the corresponding first switching device, the negative terminal of each battery pack is connected to the second end of the corresponding inductor winding through the corresponding second switching device, and the center tap of each inductor winding is connected between the positive and negative terminals of the corresponding battery pack. The N inductor windings are magnetically coupled through the magnetic core. The voltage difference between each battery pack drives the current change in each inductor winding, and energy transfer between the battery packs is achieved through the magnetic coupling.

[0005] Optionally, the system further includes a protection circuit connected to the half-bridge drive circuit; The protection circuit is configured as follows: The current of each of the switching devices, the voltage of each of the battery packs, and the temperature of the system are detected. If, based on the current of each of the switching devices, the voltage of each of the battery packs, and the temperature of the system, it is determined that the system experiences overcurrent, overvoltage, or overtemperature, then the half-bridge drive circuit is controlled to stop operating.

[0006] Optionally, the magnetic core is a toroidal magnetic core.

[0007] Optionally, the system further includes N bias resistors, each bias resistor being connected to a corresponding first switching device or second switching device; The bias resistor is used to provide a bias voltage for the corresponding group of switching devices.

[0008] Optionally, the system further includes N filter resistors, each of which is connected to a corresponding first switching device or second switching device; The filter capacitor is used to provide filtered current to the corresponding switching device.

[0009] Optionally, the absolute value of the difference between the duty cycle of the half-bridge drive circuit and 0.5 is less than a first preset threshold.

[0010] Optionally, the center tap of each inductor winding is connected to the positive terminal of the corresponding battery pack via a first connecting conductor, and the center tap of each inductor winding is connected to the negative terminal of the corresponding battery pack via a second connecting conductor. The cross-sectional areas of the first connecting conductor and the second connecting conductor are both greater than a preset area threshold.

[0011] Optionally, the number of turns of the inductor winding is greater than a second preset threshold.

[0012] Optionally, each of the first switching devices and each of the second switching devices are field-effect transistors with an on-resistance less than a preset resistance threshold.

[0013] In a second aspect, embodiments of this application provide an electric vehicle, the electric vehicle including a battery balancing system as described in any of the first aspects.

[0014] The battery balancing system provided in this application has the following beneficial effects: The battery balancing system provided in this application includes N battery packs to be balanced, a magnetic core, N inductor windings, a half-bridge drive circuit, and N switching device groups; N is greater than or equal to 2; each inductor winding corresponds to one battery pack, and each inductor winding is wound on the magnetic core, with each inductor winding including a center tap; the half-bridge drive circuit is configured to generate an alternating drive signal; each switching device group includes a first switching device and a second switching device, and the first and second switching devices in the same switching device group are configured to alternately turn on and off under the control of the alternating drive signal; the positive terminal of each battery pack is connected to the first end of the corresponding inductor winding through the corresponding first switching device, and the negative terminal of each battery pack is connected to the second end of the corresponding inductor winding through the corresponding second switching device; the center tap of each inductor winding is connected between the positive and negative terminals of the corresponding battery pack; the N inductor windings are magnetically coupled through the magnetic core, and the voltage difference between the battery packs drives the current change in each inductor winding, and energy transfer between the battery packs is achieved through magnetic coupling. The battery balancing system of this application only requires N battery packs to be balanced, one magnetic core, N inductor windings, a half-bridge drive circuit, and N switching device groups to achieve active balancing. It eliminates the need for a controller for balancing control and an analog front-end chip for collecting battery data, thus reducing the cost of active balancing. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the structure of a battery balancing system provided in an embodiment of this application; Figure 2 This is a schematic diagram of the structure of an electric vehicle provided in an embodiment of this application. Detailed Implementation

[0017] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments. The components of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0018] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this application, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0019] In traditional battery balancing technologies, active balancing methods rely on microcontroller units and analog front-end chips to work together to complete battery voltage acquisition and balancing control algorithm execution. The complexity of the system architecture mainly stems from the configuration requirements of multiple self-excited switching isolated power supplies and the necessary switch matrix design to achieve simultaneous balancing of multiple battery packs. This leads to a significant increase in the number of components, resulting in increased manufacturing costs, larger physical size, and potential fault points.

[0020] For example, in the scenario of balancing high-voltage battery packs in electric vehicles, when a battery pack consisting of multiple series-connected lithium batteries needs to be balanced in real time, the existing system must periodically collect the voltage data of each individual battery cell through a microcontroller unit and frequently switch the switching matrix composed of metal oxide semiconductor field-effect transistors based on algorithm decisions. Furthermore, in order to isolate the potential differences between different battery packs, multiple sets of optocouplers and isolation transformers need to be deployed, which results in limited circuit board layout space, extended signal transmission paths, and suppressed balancing response speed.

[0021] If the above problems are not effectively resolved, the redundancy of the components in the battery equalization system will continue to accumulate, leading to increased difficulty in cost control, difficulty in meeting the installation requirements of compact equipment in terms of physical size, and potential reduction in system reliability due to signal switching delays and increased isolation components. This will restrict the application of battery management technology in space-constrained and cost-sensitive fields.

[0022] In response, this application proposes a battery balancing system, comprising N battery packs to be balanced, a magnetic core, N inductor windings, a half-bridge drive circuit, and N groups of switching devices; where N is greater than or equal to 2. Each of the inductor windings corresponds to one of the battery packs, and each of the inductor windings is wound on the magnetic core. Each of the inductor windings includes a center tap. The half-bridge drive circuit is configured to generate an alternating drive signal; each switching device group includes a first switching device and a second switching device, the first switching device and the second switching device in the same switching device group are configured to alternately turn on and off under the control of the alternating drive signal; the positive terminal of each battery pack is connected to the first end of the corresponding inductor winding through the corresponding first switching device, the negative terminal of each battery pack is connected to the second end of the corresponding inductor winding through the corresponding second switching device, and the center tap of each inductor winding is connected between the positive and negative terminals of the corresponding battery pack; The N inductor windings are magnetically coupled through the magnetic core. The voltage difference between each battery pack drives the current change in each inductor winding, and energy transfer between the battery packs is achieved through the magnetic coupling.

[0023] For ease of understanding, the following explains some key terms in this embodiment: Battery balancing system: This system is designed to manage the voltage or state of charge differences between multiple battery packs. Through energy transfer mechanisms, it brings each battery pack to a relatively consistent state, thereby extending the overall lifespan of the battery pack and improving its performance.

[0024] Magnetic core: This is a device made of magnetic material used to concentrate and guide magnetic flux. In this system, multiple inductor windings are wound around this magnetic core to achieve magnetic coupling between them.

[0025] Inductor winding: This inductor winding is a coil formed by winding wire around a magnetic core, possessing inductive characteristics. Each inductor winding corresponds to one battery pack and plays a crucial role in energy transfer. Each inductor winding includes a center tap, which allows the inductor winding to connect to the battery pack during charging and discharging.

[0026] Half-bridge drive circuit: This is a common power electronic circuit, typically consisting of two switching devices (such as MOSFETs or IGBTs) connected in series, used to generate an alternating drive signal. This signal is used to control the on and off states of other switching devices, thereby achieving energy conversion and transfer.

[0027] Switching device group: Each switching device group contains two switching devices, such as transistors or field-effect transistors. These switching devices are alternately turned on and off under the control of an alternating drive signal to control the direction of current flow and energy transfer.

[0028] Magnetic coupling: This refers to the magnetic field generated when the current in one inductor winding changes, which passes through the magnetic core and induces an electromotive force in other inductor windings wound on the same magnetic core, thereby realizing the non-contact transfer of energy between different inductor windings.

[0029] Energy transfer: This energy transfer refers to the transfer of energy from a higher voltage battery pack to a lower voltage battery pack through a magnetic coupling mechanism, in order to achieve balance between battery packs.

[0030] This embodiment provides a battery balancing system, which includes N battery packs to be balanced, a magnetic core, N inductor windings, a half-bridge drive circuit, and N switching device groups. Here, N is set to an integer greater than or equal to 2.

[0031] Specifically, each inductor winding is configured to correspond to one battery pack. These inductor windings are all wound on the magnetic core to ensure magnetic coupling between them. Each inductor winding includes a center tap, which provides flexibility in connecting the inductor winding to the battery pack. For example, the inductor winding can be formed using a two-wire parallel winding method, where the two wires are connected in the middle to form the center tap, or a center tap can be formed by leaving a center lead during the winding process.

[0032] This half-bridge drive circuit is configured to generate an alternating drive signal. This alternating drive signal can be a square wave signal, the frequency of which and its duty cycle can be adjusted according to actual equalization requirements. For example, the half-bridge drive circuit can consist of two power switching devices (such as MOSFETs) and a driver chip, generating the required alternating drive signal by controlling the input signal to the driver chip.

[0033] Each switching device group includes a first switching device and a second switching device. The first and second switching devices within the same switching device group are configured to alternately turn on and off under the control of an alternating drive signal. For example, when the alternating drive signal is high, the first switching device is on, and the second switching device is off; when the alternating drive signal is low, the first switching device is off, and the second switching device is on. These switching devices can be bipolar transistors, field-effect transistors, or other types of semiconductor switching devices.

[0034] In terms of connection, the positive terminal of each battery pack is connected to the first end of the corresponding inductor winding via a corresponding first switching device. Simultaneously, the negative terminal of each battery pack is connected to the second end of the corresponding inductor winding via a corresponding second switching device. The center tap of each inductor winding is connected between the positive and negative terminals of the corresponding battery pack. For example, the center tap can be connected to the midpoint of the battery pack, or connected between the two ends of the battery pack via a voltage divider resistor network. This connection method allows the inductor winding to form a circuit with the battery pack, enabling charging and discharging of energy under the control of the switching devices.

[0035] The N inductor windings are magnetically coupled through the magnetic core. When the voltage of one battery pack is higher than that of the others, the current change in its corresponding inductor winding is induced in the other inductor windings through the magnetic core. Thus, the voltage difference between the battery packs drives the current change in each inductor winding, and energy transfer occurs between the battery packs through this magnetic coupling. For example, when the voltage of one battery pack is higher, its corresponding inductor winding stores energy during conduction and transfers this energy to the inductor windings of other battery packs with lower voltages through the magnetic core during turn-off, thereby achieving energy balance.

[0036] The following example will provide a more detailed explanation of the above technical solution: Suppose there is a battery pack for an electric vehicle containing three battery groups (N=3) to be balanced, labeled as battery group A, battery group B, and battery group C. At a certain moment, the voltage of battery group A is 3.8V, the voltage of battery group B is 3.6V, and the voltage of battery group C is 3.5V. At this time, the system needs to balance these three battery groups to make their voltages converge.

[0037] The battery balancing system is activated. The half-bridge drive circuit in the system begins to generate an alternating drive signal with a frequency of 100kHz and a duty cycle close to 0.5. This signal is sent to three groups of switching devices, which control the first and second switching devices corresponding to battery packs A, B, and C to alternately turn on and off.

[0038] Taking battery pack A as an example, when the alternating drive signal turns on the first switching device corresponding to battery pack A, the positive terminal of battery pack A is connected to the first end of its corresponding inductor winding through the first switching device. Simultaneously, the center tap of the inductor winding is connected between the positive and negative terminals of battery pack A. At this time, current flows from battery pack A to the inductor winding, and the inductor winding begins to store energy. Because the voltage of battery pack A is relatively high, the energy stored in its inductor winding is also relatively large.

[0039] When the alternating drive signal is reversed, causing the first switching device corresponding to battery pack A to turn off and the second switching device to turn on, the energy stored in the inductor winding begins to be released. Since all three inductor windings are wound on the same magnetic core, the change in magnetic flux generated when the inductor winding of battery pack A releases energy will be induced in the inductor windings of battery packs B and C through the magnetic core.

[0040] Specifically, the energy released from the inductor winding of battery pack A is transferred to the inductor windings of battery packs B and C, which have lower voltages, through a magnetic coupling mechanism. This energy is induced in the inductor windings of battery packs B and C, and then transmitted to battery packs B and C through their corresponding switching devices and center taps, causing their voltages to gradually increase.

[0041] This process occurs alternately at high frequency. In each cycle, energy is stored from the higher-voltage battery pack (e.g., battery pack A) through its corresponding inductor winding, and then distributed to the lower-voltage battery packs (e.g., battery packs B and C) through magnetic coupling of the core. Over time, the voltage of battery pack A gradually decreases, while the voltages of battery packs B and C gradually increase until the voltages of the three battery packs reach a relatively balanced state. Throughout this process, energy is transferred directly between the battery packs, avoiding the energy loss through resistance in traditional balancing methods.

[0042] The aforementioned battery balancing system achieves energy transfer between multiple battery packs through magnetic coupling using a single magnetic core and N inductor windings. Compared to existing technologies that require independent isolated power supplies or complex switching matrices and MCU algorithms for each battery pack, this system significantly simplifies the hardware structure and control logic. For example, existing technologies may require multiple self-excited switching isolated power supplies to achieve simultaneous balancing of multiple battery strings, resulting in large size and high cost. This system, by sharing a single magnetic core and half-bridge drive circuit, effectively reduces system complexity and cost. Furthermore, this system avoids reliance on an MCU working with a front-end AFE chip for voltage acquisition and complex algorithm processing, further reducing implementation difficulty and cost. Direct energy transfer via magnetic coupling also reduces energy loss and improves balancing efficiency. Therefore, while achieving battery balancing, this system effectively solves the problems of high cost, large size, and complex structure in existing technologies, providing a more efficient, economical, and compact battery balancing solution.

[0043] In some other embodiments, this application proposes a battery balancing system that achieves energy transfer between battery packs through magnetic coupling. However, in actual operation, due to various factors such as battery pack status, external environment, or device failure, the system may face abnormal situations such as overcurrent, overvoltage, or overtemperature. If these abnormal situations are not detected and handled in time, they may lead to damage to system components or even safety hazards, affecting the stability and reliability of the system.

[0044] In this regard, this application further proposes that the aforementioned battery balancing system also includes a protection circuit connected to the half-bridge drive circuit. This protection circuit is configured to detect the current of each switching device, the voltage of each battery pack, and the system temperature; if, based on the detected current of each switching device, the voltage of each battery pack, and the system temperature, it is determined that the system exhibits overcurrent, overvoltage, or overtemperature phenomena, then the half-bridge drive circuit is controlled to stop operating.

[0045] A protection circuit is an electronic circuit used to monitor the operating status of a system and take corresponding measures to prevent system damage or ensure safety when abnormalities are detected. This protection circuit can be implemented using a microcontroller (MCU) or digital signal processor (DSP) as its core, in conjunction with an analog front-end (AFE) circuit. The AFE is responsible for acquiring, amplifying, and filtering analog signals such as current, voltage, and temperature, and then sending the processed signals to the MCU / DSP for digitization and analysis. Alternatively, the protection circuit can also use a dedicated protection integrated circuit (IC). These ICs typically integrate multiple protection functions, enabling them to independently or collaboratively monitor system parameters and output control signals in case of abnormalities.

[0046] Monitoring the current of each switching device, the voltage of each battery pack, and the system temperature are fundamental data sources for protection circuits to determine anomalies. By acquiring these key parameters in real time, the protection circuit can gain a comprehensive understanding of the system's operating status. For current sensing, a sampling resistor can be connected in series in the current path of the switching device to measure the voltage drop across the resistor to obtain the current value; alternatively, a Hall effect sensor can be used for non-contact current measurement. For voltage sensing, a voltage divider resistor network can be used to reduce the battery pack voltage to a range acceptable to the analog-to-digital converter (ADC) before sampling; alternatively, an isolation amplifier can be used to measure the high-voltage side voltage. For temperature sensing, thermistors (NTC / PTC), thermocouples, or integrated temperature sensors can be used to measure the temperature of critical system components (such as the magnetic core, switching devices, and battery pack surfaces).

[0047] The core logic of a protection circuit is to determine whether a system is experiencing overcurrent, overvoltage, or overtemperature. This involves comparing detected data with preset thresholds to identify potential faults. This can be implemented through microcontroller programming, comparing real-time acquired current, voltage, and temperature values ​​with preset upper / lower threshold values. For example, if the current of any switching device exceeds a preset maximum current threshold, it is considered an overcurrent; if the voltage of any battery pack exceeds a preset maximum voltage threshold or falls below a preset minimum voltage threshold, it is considered an overvoltage; if the temperature at any monitoring point in the system exceeds a preset maximum temperature threshold, it is considered an overtemperature. Alternatively, a hardware comparator circuit can be used to compare the detected analog signal with a reference voltage. When the signal exceeds a preset range, the comparator outputs a high or low level to indicate an anomaly.

[0048] Stopping the half-bridge drive circuit is a direct protective measure taken by the protection circuit after detecting an anomaly. By stopping the operation of the half-bridge drive circuit, energy transmission and switching actions can be immediately interrupted, thereby preventing further deterioration of the fault. The protection circuit can directly send a low-level signal to the enable pin of the half-bridge drive circuit to put it into a shutdown state. Alternatively, the protection circuit can cut off the power supply to the half-bridge drive circuit.

[0049] The solution proposed in this application continuously monitors key parameters during the operation of the battery balancing system via a protection circuit, including the current of each switching device, the voltage of each battery pack, and the system temperature. These parameters are important indicators of the system's health and operating status. Once the protection circuit detects that any parameter exceeds the preset safe operating range (e.g., overcurrent in a switching device, overvoltage or undervoltage in a battery pack, or excessively high system temperature), the protection circuit immediately determines that an abnormality has occurred in the system, such as overcurrent, overvoltage, or overtemperature. After confirming the abnormality, the protection circuit quickly sends a control command to the half-bridge drive circuit, causing it to stop generating alternating drive signals. This will cause the first and second switching devices in each switching device group to stop alternating on and off, thereby interrupting the energy transfer process between battery packs. This rapid response mechanism effectively prevents further damage to the switching devices, inductor windings, magnetic cores, and battery packs caused by abnormal conditions, significantly improving the overall safety and operational reliability of the battery balancing system.

[0050] The following example illustrates this: the protection circuit can employ a dedicated Battery Management Unit (BMU) chip, such as TI's BQ769x0 series, or a high-performance microcontroller (such as STMicroelectronics' STM32F4 series). This microcontroller uses multiple analog-to-digital converter (ADC) channels to collect real-time data on the current of each first and second switching device (voltage drop obtained through a series low-resistance sampling resistor), the voltage of each battery pack (through a voltage divider network or isolated sampling chip), and the temperature of several key points within the system (through NTC thermistors or digital temperature sensors). The firmware running inside the microcontroller continuously compares this collected data with preset safety thresholds. For example, if the peak current of any switching device continuously exceeds a preset value for a certain period, or the voltage of any battery pack exceeds a preset upper limit, or the temperature of the system's main control chip exceeds a preset upper limit, the microcontroller immediately pulls down the enable (EN) pin connected to the half-bridge drive circuit, or stops outputting PWM control signals, thereby forcing the half-bridge drive circuit to stop operating.

[0051] Through the above technical solutions, the battery balancing system can effectively cope with abnormal situations such as overcurrent, overvoltage, or overtemperature that may occur during operation. The introduction of protection circuits enables the system to take timely protective measures when potential risks are detected, interrupting energy transmission, thereby avoiding damage to system components, extending the service life of the equipment, and significantly improving the safety and reliability of the system, ensuring the stable and balanced operation of the battery pack under various operating conditions.

[0052] In some other embodiments, this application proposes a battery balancing system comprising N battery packs to be balanced, a magnetic core, N inductor windings, a half-bridge drive circuit, and N groups of switching devices, where N is greater than or equal to 2. Each inductor winding corresponds to one battery pack and is wound on the magnetic core, including a center tap. The half-bridge drive circuit is configured to generate an alternating drive signal. Each group of switching devices includes a first switching device and a second switching device, which are alternately turned on and off under the control of the alternating drive signal. The positive terminal of each battery pack is connected to the first end of the corresponding inductor winding through the corresponding first switching device, and the negative terminal is connected to the second end of the corresponding inductor winding through the corresponding second switching device. The center tap of the inductor winding is connected between the positive and negative terminals of the corresponding battery pack. The N inductor windings are magnetically coupled through the magnetic core. The voltage difference between the battery packs drives the current change in the inductor windings, and energy transfer is achieved through magnetic coupling.

[0053] In some embodiments described above in this application, the battery balancing system achieves magnetic coupling between multiple inductor windings through a magnetic core, thereby enabling energy transfer between battery packs. However, in practical applications, the shape and structure of the magnetic core have a significant impact on magnetic coupling efficiency, electromagnetic interference, and overall system performance. An unsuitable magnetic core may lead to increased energy loss or decreased system stability.

[0054] In this regard, this application further proposes that the magnetic core in the aforementioned battery balancing system is a toroidal magnetic core. A toroidal magnetic core is a closed magnetic circuit structure characterized by magnetic flux being primarily concentrated within the core, with minimal external magnetic field leakage. Toroidal magnetic cores are typically made of materials such as ferrite, permalloy, or amorphous alloys, and inductor windings are formed by uniformly winding wires around their surface. The advantages of toroidal magnetic cores lie in their high permeability and low leakage flux, effectively improving magnetic coupling efficiency and reducing electromagnetic interference. Besides toroidal magnetic cores, the core can also be an E-type core, a can-shaped core, or a U-type core, etc. These cores also have advantages in specific applications; for example, E-type cores are easier to wind and assemble, but their leakage flux is typically greater than that of toroidal cores.

[0055] The battery balancing system of this application utilizes N inductor windings wound on a toroidal magnetic core. An alternating drive signal generated by a half-bridge drive circuit controls N groups of switching devices to alternately turn on and off, creating a loop between each battery pack and its corresponding inductor winding. When a battery pack has a higher voltage, its corresponding inductor winding generates magnetic flux in the toroidal magnetic core. This flux couples to other inductor windings through the toroidal magnetic core. Due to the closed magnetic circuit characteristic of the toroidal magnetic core, the magnetic flux can be efficiently transferred between the inductor windings, thereby driving the inductor windings of other battery packs to generate induced electromotive force, achieving energy transfer from the high-voltage battery pack to the low-voltage battery pack. The low leakage magnetic field characteristic of the toroidal magnetic core ensures efficient utilization of magnetic energy, reduces unnecessary energy loss, and lowers electromagnetic radiation generated during system operation, thus maintaining the electromagnetic compatibility within the system.

[0056] As a specific implementation, the battery balancing system can employ a toroidal core made of manganese-zinc ferrite material. This toroidal core features high permeability and low loss, making it suitable for high-frequency switching applications. N inductor windings can be uniformly wound around the outer surface of the toroidal core, ensuring tight and symmetrical magnetic coupling between the windings. For example, multi-strand enameled wire can be used for winding to reduce losses caused by the skin effect and proximity effect. The center tap of each inductor winding can be achieved by using a double-wire parallel winding followed by a center tap to ensure the symmetry of the windings. The half-bridge drive circuit can use a PWM controller to drive MOSFET switching devices, and its operating frequency can be set in the range of tens of kHz to hundreds of kHz to fully utilize the excellent high-frequency performance of the toroidal core.

[0057] By employing a toroidal magnetic core, the battery balancing system of this application significantly improves the magnetic coupling efficiency between inductor windings, ensuring efficient and rapid energy transfer between battery packs. The inherent closed magnetic circuit structure of the toroidal magnetic core effectively suppresses magnetic flux leakage, thereby reducing electromagnetic interference generated during system operation and improving the system's electromagnetic compatibility. Furthermore, toroidal magnetic cores typically have a small size and high power density, contributing to a compact design of the battery balancing system and reducing overall system energy loss, thus improving the overall performance and reliability of battery balancing.

[0058] In some embodiments described above, a battery balancing system is proposed. This system achieves energy transfer between battery packs through magnetic coupling and utilizes a half-bridge drive circuit to control switching devices to alternately turn on and off, thereby driving current changes in the inductor winding. However, in practical applications, to ensure that these switching devices can stably and reliably alternately turn on and off under the control of alternating drive signals, and to maintain their performance in the on or off states, appropriate operating conditions need to be provided for them.

[0059] In this regard, this application further proposes that the system also includes N bias resistors, each bias resistor being connected to a corresponding first switching device or second switching device; the bias resistors are used to provide a bias voltage to the corresponding group of switching devices.

[0060] The bias resistor, as mentioned above, is a resistor used to provide the voltage or current required for a stable operating point of active devices (such as transistors and field-effect transistors) in a circuit. Its function is to ensure that the switching device can quickly and accurately transition from the off state to the saturation state, or from the saturation state to the off state, when receiving a drive signal. This avoids the device operating in an unstable linear region, reduces switching losses, and improves the overall efficiency and reliability of the system. The bias resistor can be a standalone resistor element or a resistor network integrated within the drive circuit module. For example, a voltage divider resistor network can be used to generate the required bias voltage, or a series resistor can be used to limit the bias current.

[0061] The bias resistor is connected to the corresponding first or second switching device, typically by connecting it to the control terminal of the switching device (e.g., the gate of a field-effect transistor or the base of a bipolar transistor) to establish a stable DC bias level. This connection method ensures that the switching device remains in the expected on or off state even when there is no drive signal or the drive signal is in a specific state, preventing false triggering or incomplete turn-off.

[0062] The solution proposed in this application introduces N bias resistors into the battery balancing system and connects them to corresponding first or second switching devices, thereby providing stable bias voltages for these switching devices. When the half-bridge drive circuit generates an alternating drive signal, these bias voltages work in conjunction with the drive signal to ensure that the first and second switching devices can be precisely and reliably switched on and off alternately. For example, for a field-effect transistor (FET), the bias resistors can ensure that its gate-source voltage is in a clearly defined off-bias state before the drive signal arrives, or provide sufficient gate voltage to fully turn it on when the drive signal is on. This precise control is crucial for maintaining stable current changes in the inductor windings, thereby ensuring efficient magnetic coupling of the N inductor windings through the magnetic core and achieving effective energy transfer between the various battery packs. By providing stable biases for the switching devices, it is possible to effectively avoid the switching devices operating in uncertain regions, reduce switching losses, improve energy conversion efficiency, and enhance the stability and reliability of the entire battery balancing system.

[0063] The following is a specific example illustrating this implementation. In this case, the first and second switching devices can be N-channel enhancement-mode field-effect transistors (MOSFETs). The bias resistor can be configured as a gate resistor, connected in series between the output of the half-bridge drive circuit and the gate of the MOSFET. This limits the gate current and forms an RC network with the gate capacitance to control the switching speed and suppress oscillation. Furthermore, a pull-down resistor can be provided, connected between the gate and source of the MOSFET, to ensure that the gate voltage is quickly pulled down when the drive signal stops or is at a low level, reliably turning off the MOSFET and avoiding false turn-on caused by the floating gate effect.

[0064] The above technical solution provides stable bias conditions for the switching devices in the battery balancing system, thereby ensuring reliable switching of the switching devices under the control of alternating drive signals. This effectively avoids problems such as malfunction, incomplete conduction, or turn-off caused by improper bias of the switching devices, significantly improving the stability and efficiency of energy transfer in the battery balancing system, and thus extending the service life of the battery pack.

[0065] In some of the above embodiments, the battery equalization system controls the switching device group to rapidly alternate between conduction and cutoff via a half-bridge drive circuit to achieve energy transfer between battery packs. However, this high-speed switching operation inevitably generates high-frequency noise, voltage spikes, and current ripples. These electromagnetic interferences may affect the stable operation of the switching devices, reduce system efficiency, and even interfere with other sensitive circuits, thereby affecting the reliability and performance of the entire battery equalization system.

[0066] In this regard, this application further proposes that the system also includes N filter resistors, each of which is connected to a corresponding first or second switching device; the filter capacitor is used to provide filtered current to the corresponding switching device.

[0067] The filter resistor is a resistive element used to limit current, attenuate high-frequency noise, or as part of a filter network. Each filter resistor is configured to be connected to a corresponding first or second switching device. This connection can be in a series path to limit current or provide damping, or it can be part of a more complex filter network. These resistors can be conventional carbon film resistors, metal film resistors, or wire-wound resistors, and their resistance value and power rating are selected based on the specific circuit design and the expected filtering effect. The filter capacitor is a capacitive element used to smooth voltage or current waveforms and bypass high-frequency noise. Its main function is to provide filtered current to the corresponding switching device, that is, to absorb high-frequency components and transient spikes in the current by storing and releasing charge, thereby making the current flowing through the switching device more stable. The filter capacitor can be a ceramic capacitor, an electrolytic capacitor, or a film capacitor, etc., and the specific selection depends on the required capacitance value, withstand voltage, equivalent series resistance (ESR), and operating frequency range.

[0068] This application's solution aims to optimize the operating environment of switching devices in a battery equalization system by introducing N filter resistors and the filter capacitor. During battery equalization, the alternating drive signal generated by the half-bridge drive circuit causes the first and second switching devices to rapidly alternate between turning on and off. This rapid switching causes drastic changes in the current in the circuit, resulting in high-frequency harmonics and transient voltage / current spikes. The N filter resistors, connected to the corresponding first or second switching device, can limit transient current, suppress oscillations, or provide specific impedance, laying the foundation for subsequent filtering stages. The filter capacitor, through its charging and discharging characteristics, effectively absorbs these high-frequency noises and transient spikes, bypassing high-frequency components, thereby ensuring a smoother and more stable current flowing through the switching devices. The synergistic effect of the filter resistors and filter capacitors forms an effective filtering network, significantly reducing electromagnetic interference generated by switching operations, providing a "clean" power supply environment for the switching devices, and thus improving the operational stability and reliability of the switching devices.

[0069] In one specific implementation, each filter resistor can be connected in series in the gate drive path of the corresponding first or second switching device to limit the gate current and suppress ringing of the drive signal. Simultaneously, the filter capacitor can be connected in parallel at the power input terminal of the corresponding first or second switching device, for example, between the drain and source of the switching device, or between the DC bus supplying power to the switching device and ground. For instance, a 10-ohm surface-mount resistor can be used as the filter resistor, connected in series in the gate drive line of the MOSFET switching device; and the filter capacitor can be a 0.1 microfarad ceramic capacitor, connected in parallel adjacent to the power supply pin of the MOSFET to filter high-frequency noise, and can be used in conjunction with a 10 microfarad electrolytic capacitor to further smooth lower-frequency current ripple.

[0070] Through the above technical solution, the introduction of N filter resistors and the filter capacitor during energy transfer in the battery equalization system effectively suppresses high-frequency noise and transient current spikes generated by the rapid switching of the first and second switching devices. This significantly improves the current quality supplied to the switching devices, making it more stable, thereby enhancing the operating stability and reliability of the switching devices and reducing the impact of electromagnetic interference on other sensitive circuits within the system. Furthermore, by providing filtered current, the losses of the switching devices under non-ideal current conditions can be reduced, thereby improving the overall operating efficiency and lifespan of the battery equalization system.

[0071] In some other embodiments, this application proposes a battery balancing system, which includes N battery packs to be balanced, a magnetic core, N inductor windings, a half-bridge drive circuit, and N groups of switching devices. N is greater than or equal to 2. Each inductor winding corresponds to one battery pack and is wound on the magnetic core, with each inductor winding including a center tap. The half-bridge drive circuit is configured to generate an alternating drive signal, and the first and second switching devices in each group of switching devices are alternately turned on and off under the control of the alternating drive signal. The positive terminal of each battery pack is connected to the first end of the corresponding inductor winding via the corresponding first switching device, and the negative terminal is connected to the second end of the corresponding inductor winding via the corresponding second switching device. The center tap of each inductor winding is connected between the positive and negative terminals of the corresponding battery pack. The N inductor windings are magnetically coupled through the magnetic core. The voltage difference between the battery packs drives the current change in each inductor winding, and energy transfer between the battery packs is achieved through magnetic coupling.

[0072] In some embodiments described above, a battery balancing system is proposed. This system generates an alternating drive signal through a half-bridge drive circuit to control the switching device group to alternately turn on and off, thereby realizing energy transfer between battery packs. However, in actual operation, if the duty cycle control of the half-bridge drive circuit is inaccurate, it may lead to problems such as core bias, decreased energy transfer efficiency, and reduced system stability, affecting the battery balancing effect.

[0073] In response, this application further proposes that the absolute value of the difference between the duty cycle of the half-bridge drive circuit and 0.5 is less than a first preset threshold. The duty cycle of the half-bridge drive circuit refers to the ratio of the on-time of a switching device to one switching cycle in the half-bridge drive circuit. Ideally, to achieve symmetrical energy transfer and avoid core saturation, the duty cycle of the half-bridge drive circuit is typically expected to be close to 0.5 (i.e., 50%). This duty cycle can be adjusted by the pulse width of the control signal, for example, through precise control using a pulse width modulation (PWM) controller or a dedicated drive chip. The absolute value of the difference from 0.5 measures the degree to which the duty cycle of the half-bridge drive circuit deviates from the ideal value of 0.5. The use of the absolute value ensures that the degree of deviation can be accurately quantified regardless of whether the duty cycle is greater than or less than 0.5. For example, when the duty cycle is 0.48 or 0.52, the absolute value of the difference from 0.5 is 0.02. The first preset threshold is a pre-set maximum allowable value for limiting the degree of deviation of the duty cycle. This threshold can be set according to the system's requirements for equalization accuracy, efficiency, core saturation risk, and cost. For example, the first preset threshold can be set to 0.01, 0.02, or 0.05 to ensure that the duty cycle deviation is within an acceptable range. This threshold is usually determined through experimental testing, simulation analysis, or a comprehensive evaluation based on core material properties, switching device parameters, etc.

[0074] The solution in this application utilizes the aforementioned battery balancing system. A half-bridge drive circuit generates an alternating drive signal, controlling the first and second switching devices in each switching device group to alternately turn on and off. This drives current changes in each inductor winding and achieves energy transfer between battery packs through magnetic coupling via the magnetic core. To ensure energy transfer efficiency and system stability, this application further limits the absolute value of the difference between the duty cycle of the half-bridge drive circuit and 0.5 to less than a first preset threshold. When the duty cycle of the half-bridge drive circuit is precisely controlled close to 0.5, it ensures that the current flowing through the inductor winding is essentially symmetrical in both forward and reverse magnetization during each switching cycle. This symmetry helps prevent DC bias in the magnetic core, thus avoiding core saturation. Core saturation causes a sharp drop in inductance, preventing the inductor winding from effectively storing and releasing energy, thereby reducing energy transfer efficiency and potentially damaging the switching devices. By limiting the deviation of the duty cycle within the first preset threshold, the system can maintain the normal operating state of the magnetic core, ensuring the effective energy conversion capability of the inductor winding, thereby achieving efficient and stable energy balancing between battery packs. This precise duty cycle control enables the system to minimize losses and improve balancing speed and accuracy during energy transfer.

[0075] In one specific implementation, the duty cycle of the half-bridge drive circuit can be precisely controlled by a microcontroller (MCU). This MCU can integrate a pulse width modulation (PWM) module to generate a drive signal with a specific duty cycle. For example, the MCU can dynamically adjust the duty cycle of the PWM signal using a closed-loop control algorithm based on parameters such as battery voltage and current detected in real time by the system. To ensure that the absolute value of the difference between the duty cycle and 0.5 is less than a first preset threshold, the MCU can periodically measure the actual output duty cycle and compare it to 0.5. If the measured duty cycle deviates from 0.5 by an absolute value exceeding the first preset threshold, the MCU can immediately adjust the PWM output to correct the duty cycle. Alternatively, a dedicated half-bridge drive chip can be used, which integrates duty cycle control and protection mechanisms to automatically maintain the duty cycle within a range close to 0.5 and provide overcurrent and undervoltage protection functions. For example, a drive chip with adaptive dead-time control and duty cycle correction functions can be used to ensure the accuracy and symmetry of the drive signal.

[0076] By limiting the absolute value of the difference between the duty cycle of the half-bridge drive circuit and 0.5 to within a first preset threshold, DC bias of the magnetic core during long-term operation can be effectively avoided, thus preventing core saturation. This not only significantly improves the energy storage and release efficiency of the inductor winding and reduces energy loss during transmission, but also extends the service life of the magnetic core and switching devices. Simultaneously, precise duty cycle control ensures a more balanced and stable energy transfer between battery packs, improving the reliability and balancing accuracy of the entire battery balancing system, thereby optimizing the overall performance and lifespan of the battery pack.

[0077] In some embodiments described above, a battery balancing system is proposed. This system achieves energy transfer between battery packs through magnetic coupling, wherein the center tap of each inductor winding is connected between the positive and negative terminals of the corresponding battery pack. However, in actual operation, when there is a large voltage difference between battery packs for energy transfer, the current flowing through the center tap connecting conductor may be large. If the current-carrying capacity of the connecting conductor is insufficient, it may lead to excessive connection resistance, thereby increasing energy loss and localized heating, affecting balancing efficiency and system stability.

[0078] In this regard, this application further proposes that the center tap of each inductor winding is connected to the positive terminal of the corresponding battery pack through a first connecting conductor, and the center tap of each inductor winding is connected to the negative terminal of the corresponding battery pack through a second connecting conductor, wherein the cross-sectional area of ​​the first connecting conductor and the cross-sectional area of ​​the second connecting conductor are both greater than a preset area threshold.

[0079] The first and second connecting conductors are the physical media used to establish an electrical connection between the center tap of the inductor winding and the positive and negative terminals of the battery pack. They can be in the form of wires, copper traces on a printed circuit board (PCB), or copper busbars. Their main function is to carry the current flowing from the center tap to the battery pack or from the battery pack to the center tap, ensuring efficient energy transfer. The phrase "cross-sectional area greater than the preset area threshold" refers to the cross-sectional area of ​​the connecting conductors, which directly determines the conductor's current-carrying capacity and resistance. As the conductor's cross-sectional area increases, its resistance decreases, thereby reducing the voltage drop and heat generated when current flows. The preset area threshold is a minimum cross-sectional area value determined based on factors such as the system's maximum expected current, allowable temperature rise, and efficiency requirements. This feature aims to ensure that the connecting conductors have sufficient current-carrying capacity to handle the large currents that may occur during battery equalization and effectively reduce energy loss.

[0080] The proposed solution utilizes a first and second connecting conductor, both with cross-sectional areas larger than a preset threshold, to connect the center tap of each inductor winding to the corresponding positive and negative terminals of the battery pack. During battery balancing system operation, when the half-bridge drive circuit generates an alternating drive signal to control the switching device group to alternately turn on and off, the current in the inductor winding changes and magnetically couples through the magnetic core, thereby achieving energy transfer between battery packs. During this energy transfer process, the center tap, as the midpoint of the inductor winding, needs to carry the balancing current through its connecting conductor to the positive and negative terminals of the battery pack. By increasing the cross-sectional area of ​​the first and second connecting conductors, the equivalent resistance of these connection paths can be significantly reduced. This reduction in resistance directly leads to a substantial decrease in voltage drop and power loss (I²R loss) on the connecting conductors under the same current. This not only reduces energy loss during transmission and improves energy transfer efficiency but also effectively suppresses the temperature rise of the connecting conductors due to high current, thus ensuring system stability and reliability. This design ensures that the connection path does not become a bottleneck during high-current energy transfer between battery packs, thereby optimizing overall balancing performance.

[0081] In one specific implementation, the center tap of each inductor winding can be connected to the positive and negative terminals of the corresponding battery pack via multi-stranded copper wire as the first and second connecting conductors, respectively. The total cross-sectional area of ​​these multi-stranded copper wires can be designed to be much larger than the minimum current-carrying cross-sectional area allowed by the system under maximum equalization current. Alternatively, when implemented on a printed circuit board, the copper traces connecting the center tap to the positive and negative terminals of the battery pack can be designed as multi-layered parallel wide traces to ensure that their total effective cross-sectional area meets the requirement of being greater than a preset area threshold.

[0082] Through the above technical solution, since the cross-sectional areas of both the first and second connecting conductors are greater than a preset area threshold, the path resistance between the center tap of the connecting inductor winding and the positive and negative terminals of the battery pack is significantly reduced. This effectively reduces energy loss and heat generation on the connecting conductors during battery equalization, especially during high-current energy transfer. Therefore, the battery equalization system of this application can transfer energy with higher efficiency, reduce the temperature rise during system operation, and thus improve the overall efficiency of battery equalization and the long-term operational stability and reliability of the system.

[0083] In other embodiments, this application proposes a battery balancing system that uses N inductor windings magnetically coupled on a magnetic core and utilizes a half-bridge drive circuit and N switching device groups to achieve energy transfer between battery packs. However, in practical applications, if the number of turns of the inductor windings is not properly designed, the inductance may be too small, resulting in the inductor being unable to effectively store and release sufficient energy in each switching cycle. This affects the efficiency of energy transfer and the balancing speed, and may even cause the switching devices to experience excessive current stress.

[0084] In this regard, this application further proposes that the number of coil turns of the inductor winding is greater than a second preset threshold.

[0085] The number of turns in an inductor winding refers to the number of conductor coils wound around the magnetic core. The number of turns is one of the key parameters determining the inductance value of an inductor winding; all other things being equal, the more turns, the greater the inductance. The number of turns can be increased in several ways. For example, it can be directly increased by increasing the number of turns of the wire wound around the magnetic core; or, within a limited magnetic core volume, the effective number of turns can be increased by selecting thinner wires, using multi-strand winding, or optimizing the winding structure (such as tight winding or layered winding). The second preset threshold is a pre-set value used to limit the lower limit of the inductor winding's number of turns. This threshold is set to ensure that the inductor winding has sufficient inductance to meet the requirements of the battery balancing system for energy storage, transmission efficiency, and system stability. The second preset threshold can be determined based on various methods. For example, it can be precisely calculated through theoretical calculations, simulation modeling, or empirical formulas based on parameters such as the voltage range of the battery pack, the equalization current requirement, the switching frequency, the characteristics of the magnetic core material, and the desired energy transfer efficiency. Alternatively, it can be determined by experimentally testing the system performance under different numbers of turns, such as equalization speed, efficiency, temperature rise, and stress of the switching devices, thereby selecting an optimal empirical value as the second preset threshold.

[0086] The solution in this application ensures that each inductor winding has a sufficiently large inductance by designing the number of coil turns to be greater than a second preset threshold. Under the control of the alternating drive signal generated by the half-bridge drive circuit, the first and second switching devices alternately turn on and off, enabling the inductor winding to store and release energy during charging and discharging. A sufficiently large inductance effectively limits the ripple of the inductor current, keeping the current change rate within a controllable range, thereby reducing the current surge experienced by the switching devices during turn-on and turn-off, and lowering switching losses. Simultaneously, a larger inductance also means that the inductor winding can store more energy in each switching cycle, which is crucial for achieving efficient energy transfer. Through magnetic coupling, this energy stored in the inductor can be transferred between different battery packs, thereby achieving voltage equalization between battery packs. When the number of coil turns of the inductor winding meets the condition of being greater than the second preset threshold, the system can ensure that the inductor winding provides stable energy storage and transmission capabilities over a wide voltage range and under different equalization requirements, thereby optimizing the efficiency and reliability of the entire equalization process.

[0087] One specific implementation example is as follows: The inductor winding can be made by winding enameled copper wire on a toroidal magnetic core. For example, if the second preset threshold is determined to be 15 turns according to the system design requirements, then the number of turns of each inductor winding can be designed to be 20 turns. During the winding process, layered winding or tight winding can be used to ensure that the required number of turns is achieved within the limited magnetic core window area and to maintain good coupling characteristics. For example, a two-wire parallel winding method can be used, with the two wires serving as the first and second ends of the inductor winding, and the middle tap serving as the center tap.

[0088] By designing the number of turns of the inductor winding to be greater than a second preset threshold, the battery balancing system of this application can ensure that the inductor winding has sufficient inductance. This helps to effectively limit the ripple of the inductor current, reduce the current stress on the switching devices, thereby reducing switching losses and improving the overall efficiency of the system. Simultaneously, sufficient inductance allows the inductor winding to store and transfer more energy in each switching cycle, thereby accelerating the energy transfer speed between battery packs and shortening the balancing time. Furthermore, a larger inductance also helps to improve system stability, reducing resonance or oscillation phenomena caused by insufficient inductance, thus making the battery balancing system more reliable and efficient.

[0089] In some other embodiments, this application proposes a battery balancing system, including N battery packs to be balanced, a magnetic core, N inductor windings, a half-bridge drive circuit, and N groups of switching devices. N is greater than or equal to 2. Each inductor winding corresponds to one battery pack, and each inductor winding is wound on the magnetic core, with each inductor winding including a center tap. The half-bridge drive circuit is configured to generate an alternating drive signal. Each group of switching devices includes a first switching device and a second switching device, and the first and second switching devices in the same group are configured to alternately turn on and off under the control of the alternating drive signal. The positive terminal of each battery pack is connected to the first end of the corresponding inductor winding through the corresponding first switching device, and the negative terminal of each battery pack is connected to the second end of the corresponding inductor winding through the corresponding second switching device. The center tap of each inductor winding is connected between the positive and negative terminals of the corresponding battery pack. The N inductor windings are magnetically coupled through the magnetic core, and the voltage difference between the battery packs drives the current change in each inductor winding, thereby transferring energy between the battery packs through magnetic coupling. However, in practical applications, switching devices will generate certain power losses when in the conducting state, especially under high current or long-term operating conditions. These losses will cause the switching devices to heat up, thereby affecting the overall efficiency and reliability of the system, and may even shorten the service life of the devices.

[0090] To address this, this application further proposes that each of the first and second switching devices be field-effect transistors (FETs) with an on-resistance less than a preset resistance threshold. A field-effect transistor (FET) is a voltage-controlled device that controls its conduction or cutoff by applying a voltage to its gate, thereby controlling the flow of current. Common FET types include metal-oxide-semiconductor field-effect transistors (MOSFETs), junction field-effect transistors (JFETs), and FETs made of wide-bandgap semiconductor materials (such as silicon carbide (SiC) or gallium nitride (GaN). These devices are widely used in power management and switching circuits due to their high switching speed and low drive power. On-resistance refers to the resistance value presented by the main current path of the FET (e.g., between the drain and source of a MOSFET) when it is fully turned on. When current flows through the on-resistance, power loss in the form of I²R is generated and converted into heat. Designing or selecting the on-resistance to be less than a preset resistance threshold aims to minimize this conduction loss, thereby reducing device heating and improving energy conversion efficiency. For example, the equivalent on-resistance can be reduced by selecting low on-resistance MOSFETs with advanced technology or by using multiple MOSFETs in parallel.

[0091] The solution proposed in this application effectively solves the aforementioned problems by configuring each first and second switching device in the battery equalization system as a field-effect transistor (FET) with an on-resistance less than a preset resistance threshold. During battery equalization, the half-bridge drive circuit generates an alternating drive signal to control the first and second switching devices in each switching device group to alternately turn on and off, thereby achieving energy storage and release in N inductor windings and magnetic coupling through the magnetic core, ultimately completing the energy transfer between the battery packs. When these switching devices use FETs with extremely low on-resistance, the heat generated by the current flowing through the switching devices during their on-state is significantly reduced. This is because power loss is proportional to the square of the current and the on-resistance; reducing the on-resistance directly and significantly reduces power loss. Therefore, the system's energy loss is minimized throughout the entire energy transfer cycle, thereby improving the efficiency of battery equalization. Simultaneously, due to the reduced heat generation of the switching devices themselves, the system's heat dissipation requirements are also reduced, which helps simplify system design and improve the system's stability and reliability during long-term operation. This low-loss switching characteristic enables the battery balancing system to maintain a low temperature rise under high-power or high-frequency operating environments, ensuring continuous optimization of system performance.

[0092] The following is a concrete example. In the battery balancing system described above, the first and second switching devices can be specifically selected as N-channel enhancement-mode power MOSFETs. For example, models with low on-resistance characteristics can be selected, such as devices with on-resistance in the range of a few milliohms (e.g., less than 5 milliohms). The gates of these MOSFETs are driven by a half-bridge drive circuit to achieve fast and precise switching action. To ensure that the on-resistance meets the requirements, a specific preset resistance threshold can be set during the design phase based on the battery pack's voltage, current, and expected balancing power, and a MOSFET that meets this threshold can be selected. For example, for a battery balancing system with a rated current of 50A, if the allowable single-channel power consumption of the switching device is 0.5W, then the preset on-resistance threshold can be calculated as 0.5W / (50A)^2 = 0.2 milliohms. In practical applications, multiple low-on-resistance MOSFETs can be used in parallel to further reduce the equivalent on-resistance and meet more stringent power consumption and temperature rise requirements.

[0093] By replacing the first and second switching devices in the battery equalization system with field-effect transistors (FETs) whose on-resistance is less than a preset resistance threshold using the above technical solution, the power loss of the switching devices in the on-state can be significantly reduced. This not only improves the energy conversion efficiency during battery equalization and reduces unnecessary energy waste, but also effectively suppresses the heat generation of the switching devices and lowers the system's operating temperature. Lower operating temperatures help extend the lifespan of the switching devices and even the entire battery equalization system, improving the system's long-term stability and reliability. Furthermore, due to the reduced heat generation, the system's requirements for heat dissipation structures are also reduced, potentially leading to a smaller system size and weight, and lower manufacturing costs.

[0094] The following provides a specific embodiment of a battery balancing system. Please refer to [link / reference]. Figure 1 , Figure 1 This is a schematic diagram of a battery balancing system provided in an embodiment of this application.

[0095] like Figure 1 As shown, the battery balancing system may include two battery packs to be balanced, a magnetic core, two inductor windings (inductor windings composed of L7 and L8, and inductor windings composed of L5 and L6), a half-bridge drive circuit (composed of half-bridge chip, C89, C88, C87, C86, R8, R7, R6, and R5), and two switching device groups (switching device group composed of U7 and U8, and switching device group composed of U5 and U6).

[0096] The specific functions of the battery pack, magnetic core, inductor winding, half-bridge drive circuit, and switching device group to be balanced in the battery balancing system can be found in the relevant descriptions of the above embodiments, and will not be repeated here.

[0097] In other embodiments, this application proposes an electric vehicle; please refer to [link to relevant documentation]. Figure 2 , Figure 2 This is a schematic diagram of the structure of an electric vehicle provided in an embodiment of this application.

[0098] like Figure 2 As shown, the electric vehicle includes the aforementioned battery balancing system. The specific functions of this battery balancing system can be found in [reference needed]. Figure 1 The relevant descriptions of the corresponding embodiments will not be repeated here.

[0099] This application effectively solves the problems of high cost, large size, and complex structure in existing battery balancing systems because it directly integrates a single magnetic core with N inductor windings via magnetic coupling and utilizes the voltage difference between battery packs to drive energy transfer. This avoids the reliance on MCUs and front-end AFE chips for voltage acquisition and complex algorithm processing found in traditional solutions. Specifically, this battery balancing system eliminates the need for multiple self-excited switching isolated power supplies, numerous optocouplers, or isolation transformers, and also eliminates the complex switching logic of the switching matrix, significantly simplifying the hardware structure. For example, in electric vehicle applications, this system only requires a single magnetic core and a half-bridge drive circuit to achieve simultaneous balancing of multiple battery strings, reducing transformer size and cost, as well as the number of MOSFETs and the complexity of the control circuit. Through this technical solution, electric vehicles can achieve efficient battery balancing with a compact structure during operation, avoiding energy loss through resistor dissipation, thereby extending the overall battery pack lifespan and improving vehicle energy efficiency. Compared to existing technologies, this solution effectively overcomes the drawbacks of large size, high cost, and structural redundancy while ensuring balancing performance, providing an economical and reliable battery management solution for electric vehicles.

[0100] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A battery equalization system, characterized by, It includes N battery packs to be balanced, one magnetic core, N inductor windings, a half-bridge drive circuit, and N groups of switching devices; N is greater than or equal to 2; Each of the inductor windings corresponds to one of the battery packs, and each of the inductor windings is wound on the magnetic core. Each inductor winding includes a center tap. The half-bridge drive circuit is configured to generate alternating drive signals; Each of the switching device groups includes a first switching device and a second switching device, wherein the first switching device and the second switching device in the same switching device group are configured to alternately turn on and off under the control of the alternating drive signal; The positive terminal of each battery pack is connected to the first end of the corresponding inductor winding through the corresponding first switching device, the negative terminal of each battery pack is connected to the second end of the corresponding inductor winding through the corresponding second switching device, and the center tap of each inductor winding is connected between the positive and negative terminals of the corresponding battery pack. The N inductor windings are magnetically coupled through the magnetic core. The voltage difference between each battery pack drives the current change in each inductor winding, and energy transfer between the battery packs is achieved through the magnetic coupling.

2. The system of claim 1, wherein, The system also includes a protection circuit connected to the half-bridge drive circuit; The protection circuit is configured as follows: The current of each of the switching devices, the voltage of each of the battery packs, and the temperature of the system are detected. If, based on the current of each of the switching devices, the voltage of each of the battery packs, and the temperature of the system, it is determined that the system experiences overcurrent, overvoltage, or overtemperature, then the half-bridge drive circuit is controlled to stop operating.

3. The system of claim 1, wherein, The magnetic core is a toroidal core.

4. The system of claim 1, wherein, The system also includes N bias resistors, each bias resistor being connected to a corresponding first switching device or second switching device; The bias resistor is used to provide a bias voltage for the corresponding group of switching devices.

5. The system of claim 1, wherein, The system also includes N filter resistors, each of which is connected to a corresponding first or second switching device. The filter capacitor is used to provide filtered current to the corresponding switching device.

6. The system according to claim 1, characterized in that, The absolute value of the difference between the duty cycle of the half-bridge drive circuit and 0.5 is less than the first preset threshold.

7. The system according to claim 1, characterized in that, The center tap of each inductor winding is connected to the positive terminal of the corresponding battery pack via a first connecting conductor, and the center tap of each inductor winding is connected to the negative terminal of the corresponding battery pack via a second connecting conductor. The cross-sectional areas of the first connecting conductor and the second connecting conductor are both greater than a preset area threshold.

8. The system according to claim 1, characterized in that, The number of turns in the inductor winding is greater than a second preset threshold.

9. The system according to claim 1, characterized in that, Each of the first switching devices and each of the second switching devices are field-effect transistors with an on-resistance less than a preset resistance threshold.

10. An electric vehicle, characterized in that, The electric vehicle includes the battery balancing system as described in any one of claims 1 to 9.

Images