Battery active equalization circuit of electric vehicle and electric vehicle

Abstract

The utility model provides a battery active equalization circuit of an electric vehicle and the electric vehicle, the circuit comprises N control circuits, and each control circuit comprises a battery module and an equalization circuit; the DCDC chip is used for acquiring the voltage of the battery system and converting the voltage of the battery system into PWM waves; the amplified PWM waves push the transformer to work; when the PWM wave is at a high level, the transformer stores energy; when the PWM wave is at a low level, the primary side passes through active clamping follow current, and the secondary side outputs a current signal to charge a battery through a rectifier diode; after a current signal is established, the output current sampling resistor converts the current signal into a voltage signal and transmits the voltage signal to the isolation operational amplifier; and the isolation operational amplifier amplifies the voltage signal to obtain an amplified voltage signal, and transmits the amplified voltage signal to the DCDC chip, so that the DCDC chip processes the amplified voltage signal to generate an amplified feedback signal, and adjusts the output PWM wave according to the amplified feedback signal.

Description

Active battery balancing circuit for electric vehicles and electric vehicles Technical Field

[0001] This utility model relates to the field of electric vehicle technology, and in particular to an active battery balancing circuit for electric vehicles and electric vehicles. Background Technology

[0002] In recent years, with the increasingly widespread application of lithium-ion batteries in two-wheeled electric vehicles, battery safety issues have become increasingly prominent. Because of slight inconsistencies in battery production, these variations, along with current unevenness, temperature differences, and internal resistance variations, gradually increase voltage differences after the batteries are assembled into a battery pack. Since individual battery cells have relatively low voltages—for example, the rated voltage of a single lithium iron phosphate cell is 3.2V, while that of a ternary lithium battery is 3.7V—if an electric vehicle's system voltage requirement is 74V, 20 ternary lithium batteries would need to be connected in series, while 23 lithium iron phosphate batteries would require 23. In such a large battery system, any inconsistency in individual cell voltages will reduce the overall usable energy, leading to overcharging, over-discharging, and even battery explosions and fires.

[0003] Currently, the common technology is passive equalization, which uses a resistor discharge method: a resistor and a controllable switch (usually a MOSFET) are connected to each battery string. When the BMS detects a large difference in the voltage of individual cells in the battery system, equalization is activated, opening the resistor corresponding to the cell with the higher voltage than the average voltage to discharge it; when all voltage differences are less than a set value (usually 20mV), equalization is turned off.

[0004] However, the above method has the following drawbacks: 1) This balancing method is energy-consuming and will cause energy waste; 2) During the balancing process, the resistor will generate a lot of heat, which will accumulate and have a negative impact on the battery and the BMS PCBA; 3) When only one string of voltage is low, all the remaining normal cells need to be discharged, which results in low balancing efficiency; 4) The balancing current is small. Summary of the Invention

[0005] In view of this, the purpose of this utility model is to provide an active battery balancing circuit for electric vehicles and an electric vehicle, which uses an active balancing method to balance the battery, achieving a maximum balancing current of 1A, with high efficiency and fast speed; the balancing method uses energy replenishment, resulting in less heat and less energy loss.

[0006] In a first aspect, this utility model embodiment provides an active battery balancing circuit for an electric vehicle. The circuit includes N control circuits, each control circuit including a battery module and a balancing circuit. The battery module includes N batteries connected in parallel. The balancing circuit includes a DC-DC chip, an input filter capacitor, an active clamp, a transformer, a rectifier diode, an output filter capacitor, an output current sampling resistor, and an isolation operational amplifier.

[0007] The DC-DC chip is used to acquire the battery system voltage, convert the battery system voltage into a PWM wave, amplify the PWM wave to obtain an amplified PWM wave, and drive the transformer to work through the amplified PWM wave.

[0008] The transformer is used to store energy when the PWM wave is high; when the PWM wave is low, the primary side is used for active clamping freewheeling, and the secondary side is used to charge the battery by outputting a current signal through a rectifier diode.

[0009] The output current sampling resistor is used to convert the current signal into a voltage signal and transmit it to the isolation operational amplifier after the current signal is established.

[0010] The isolated operational amplifier is used to amplify the voltage signal to obtain an amplified voltage signal, and then transmit the amplified voltage signal to the DC-DC chip, so that the DC-DC chip processes the amplified voltage signal to generate an amplified feedback signal, and adjusts the output PWM wave according to the amplified feedback signal.

[0011] Furthermore, the DC-DC chip includes a MOSFET;

[0012] The MOS transistor is used to amplify the PWM wave to obtain the amplified PWM wave.

[0013] Furthermore, the DC-DC chip is used to receive the amplified voltage signal sent by the isolated operational amplifier via the FB pin.

[0014] Furthermore, the DC-DC chip is used to process the amplified voltage signal through an internal error amplifier to obtain a feedback signal; and to amplify the feedback signal to obtain the amplified feedback signal.

[0015] Furthermore, the DC-DC chip is used to adjust the output PWM wave according to the amplified feedback signal through an internal PWM generator.

[0016] Furthermore, the active clamp includes diode D2 and diode D1.

[0017] Furthermore, N is a positive integer.

[0018] Furthermore, the battery system voltage is VCC.

[0019] Secondly, embodiments of this utility model provide an electric vehicle, including the battery active balancing circuit of the electric vehicle as described above.

[0020] This utility model embodiment provides an active battery balancing circuit for an electric vehicle and an electric vehicle. The circuit includes N control circuits, each including a battery module and an balancing circuit. The battery module includes N batteries connected in parallel. The balancing circuit includes a DC-DC chip, an input filter capacitor, an active clamp, a transformer, a rectifier diode, an output filter capacitor, an output current sampling resistor, and an isolation operational amplifier. The DC-DC chip acquires the battery system voltage and converts it into a PWM wave. The PWM wave is amplified to obtain an amplified PWM wave, which drives the transformer. When the PWM wave is high, the transformer stores energy; when the PWM wave is low, the transformer stores energy. The primary side uses an active clamp freewheeling current, while the secondary side charges the battery by outputting a current signal through a rectifier diode. Once the current signal is established, the output current sampling resistor converts the current signal into a voltage signal and sends it to an isolated operational amplifier. The isolated operational amplifier amplifies the voltage signal and sends it to a DC-DC chip, which processes the amplified voltage signal to generate an amplified feedback signal. The output PWM wave is then adjusted based on the amplified feedback signal. Active balancing is used to balance the battery, achieving a maximum balancing current of 1A, which is efficient and fast. The battery is balanced using a supplementary energy method, resulting in low heat generation and minimal energy loss.

[0021] Other features and advantages of this invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objectives and other advantages of this invention are realized and obtained through the structures particularly pointed out in the description, claims, and drawings.

[0022] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 is a schematic diagram of the active battery balancing circuit of the electric vehicle provided in Embodiment 1 of this utility model;

[0025] Figure 2 is a schematic diagram of the control circuit structure provided in Embodiment 1 of this utility model;

[0026] Figure 3 is a schematic diagram of the active battery balancing circuit structure of the electric vehicle provided in Embodiment 2 of this utility model. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0028] To facilitate understanding of this embodiment, the following is a detailed description of the embodiment of this utility model.

[0029] Example 1:

[0030] Figure 1 is a schematic diagram of the active battery balancing circuit of an electric vehicle provided in Embodiment 1 of this utility model.

[0031] Referring to Figure 1, the circuit includes N control circuits, where N is a positive integer. When N = 1, the circuit includes 1 control circuit; when N = 2, the circuit includes 2 control circuits; and when N = 3, the circuit includes 3 control circuits.

[0032] Referring to Figure 2, the control circuit includes a battery module and an equalization circuit. The battery module includes N batteries connected in parallel. The equalization circuit includes a DC-DC chip U1, an input filter capacitor C1, an active clamp, a transformer T1, a rectifier diode D3, an output filter capacitor, an output current sampling resistor R4, and an isolation operational amplifier U4. The active clamp includes diodes D2 and D1, and the output filter capacitors include C2 and C3.

[0033] The DC-DC chip is used to obtain the battery system voltage, convert the battery system voltage into a PWM wave, amplify the PWM wave to obtain an amplified PWM wave, and drive the transformer to work through the amplified PWM wave.

[0034] The transformer is used to store energy when the PWM wave is high; when the PWM wave is low, the primary side provides active clamping freewheeling current, and the secondary side charges the battery by outputting a current signal through a rectifier diode.

[0035] The output current sampling resistor is used to convert the current signal into a voltage signal after the current signal is established and transmit it to the isolation operational amplifier.

[0036] An isolation operational amplifier is used to amplify a voltage signal, obtain an amplified voltage signal, and then transmit the amplified voltage signal to a DC-DC chip. The DC-DC chip processes the amplified voltage signal and generates an amplified feedback signal, which is used to adjust the output PWM wave.

[0037] Referring to Figure 3, the circuit includes three control circuits. The input terminal VCC of each control circuit is connected in parallel, and the output terminal of each control circuit is connected in series. For example, if the battery pack has 30 cells, then 10 copies of the above circuit are needed.

[0038] Furthermore, DC-DC chips include MOSFETs;

[0039] MOSFETs are used to amplify PWM waves to obtain amplified PWM waves.

[0040] Furthermore, the DC-DC chip is used to receive the amplified voltage signal sent by the isolated operational amplifier via the FB pin.

[0041] Furthermore, the DC-DC chip is used to process the amplified voltage signal through an internal error amplifier to obtain a feedback signal; the feedback signal is then amplified to obtain an amplified feedback signal.

[0042] Furthermore, the DC-DC chip is used to adjust the output PWM wave based on the amplified feedback signal through an internal PWM generator.

[0043] Specifically, the error amplifier inside the DC-DC chip amplifies the feedback signal and sends it to the PWM generator. The PWM generator adjusts the output PWM to stabilize the output current.

[0044] This application employs an active balancing method to balance the batteries, achieving a maximum balancing current of 1A, which is highly efficient and fast. It also uses a replenishment method for balancing, resulting in minimal heat generation and energy loss. Even if only one battery cell has a low voltage, the application can accurately locate that cell and replenish the power to that single cell.

[0045] Furthermore, N is a positive integer.

[0046] Furthermore, the battery system voltage is VCC.

[0047] This utility model embodiment provides an electric vehicle, including the battery active balancing circuit of the electric vehicle as described above.

[0048] This utility model embodiment provides an active battery balancing circuit for an electric vehicle and an electric vehicle. The circuit includes N control circuits, each including a battery module and an balancing circuit. The battery module includes N batteries connected in parallel. The balancing circuit includes a DC-DC chip, an input filter capacitor, an active clamp, a transformer, a rectifier diode, an output filter capacitor, an output current sampling resistor, and an isolation operational amplifier. The DC-DC chip acquires the battery system voltage and converts it into a PWM wave. The PWM wave is amplified to obtain an amplified PWM wave, which drives the transformer. When the PWM wave is high, the transformer stores energy; when the PWM wave is low, the transformer stores energy. The primary side uses an active clamp freewheeling current, while the secondary side charges the battery by outputting a current signal through a rectifier diode. Once the current signal is established, the output current sampling resistor converts the current signal into a voltage signal and sends it to an isolated operational amplifier. The isolated operational amplifier amplifies the voltage signal and sends it to a DC-DC chip, which processes the amplified voltage signal to generate an amplified feedback signal. The output PWM wave is then adjusted based on the amplified feedback signal. Active balancing is used to balance the battery, achieving a maximum balancing current of 1A, which is efficient and fast. The battery is balanced using a supplementary energy method, resulting in low heat generation and minimal energy loss.

[0049] The computer program product provided in this embodiment of the present invention includes a computer-readable storage medium storing program code. The instructions included in the program code can be used to execute the methods described in the preceding method embodiments. For specific implementation details, please refer to the method embodiments, which will not be repeated here.

[0050] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the system and apparatus described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0051] Furthermore, in the description of the embodiments of this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.

[0052] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this utility model, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this utility model. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0053] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0054] Finally, it should be noted that the above-described embodiments are merely specific implementations of this utility model, used to illustrate the technical solution of this utility model, and not to limit it. The protection scope of this utility model is not limited thereto. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the technical scope disclosed in this utility model. These modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model, and should all be covered within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the protection scope of the claims.

Claims

1. A battery active balancing circuit for an electric vehicle, characterized in that, The circuit includes N control circuits, each comprising a battery module and an equalization circuit. The battery module comprises N batteries connected in parallel. The equalization circuit includes a DC-DC chip, an input filter capacitor, an active clamp, a transformer, a rectifier diode, an output filter capacitor, an output current sampling resistor, and an isolation operational amplifier. The DC-DC chip acquires the battery system voltage and converts it into a PWM wave. The PWM wave is amplified to obtain an amplified PWM wave, which drives the transformer. The transformer is used to perform [operation / function] when the PWM wave is high. Energy storage; when the PWM wave is low, the primary side uses an active clamp for freewheeling, and the secondary side uses a rectifier diode to output a current signal to charge the battery; the output current sampling resistor is used to convert the current signal into a voltage signal after the current signal is established, and transmit it to the isolation operational amplifier; the isolation operational amplifier is used to amplify the voltage signal to obtain an amplified voltage signal, and transmit the amplified voltage signal to the DC-DC chip, so that the DC-DC chip processes the amplified voltage signal to generate an amplified feedback signal, and adjusts the output PWM wave according to the amplified feedback signal.

2. The battery active balancing circuit for electric vehicles according to claim 1, characterized in that, The DC-DC chip includes a MOS transistor; the MOS transistor is used to amplify the PWM wave to obtain the amplified PWM wave.

3. The battery active balancing circuit for electric vehicles according to claim 1, characterized in that, The DC-DC chip is used to receive the amplified voltage signal sent by the isolated operational amplifier through the FB pin.

4. The battery active balancing circuit for electric vehicles according to claim 3, characterized in that, The DC-DC chip is used to process the amplified voltage signal through an internal error amplifier to obtain a feedback signal; and to amplify the feedback signal to obtain the amplified feedback signal.

5. The battery active balancing circuit for electric vehicles according to claim 4, characterized in that, The DC-DC chip is used to adjust the output PWM wave according to the amplified feedback signal through an internal PWM generator.

6. The battery active balancing circuit for electric vehicles according to claim 1, characterized in that, The active clamp includes diode D2 and diode D1.

7. The battery active balancing circuit for electric vehicles according to claim 1, characterized in that, N is a positive integer.

8. The battery active balancing circuit for electric vehicles according to claim 1, characterized in that, The battery system voltage is VCC.

9. An electric vehicle, characterized in that, Includes the battery active balancing circuit of the electric vehicle as described in any one of claims 1 to 8.

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