Multi-battery pack equalization circuit and battery pack series-parallel equalization system

Abstract

The utility model provides a multi-battery pack equalization circuit and a battery pack series-parallel equalization system. The multi-battery pack equalization circuit comprises a plurality of equalization sub-circuits, each equalization sub-circuit comprises a battery cell module, an equalization transformer, a primary side electronic switch tube, an equalization positive end switch, an equalization negative end switch, an output rectifier diode and an output capacitor, and the plurality of battery packs are connected in series and / or in parallel; the first end of the secondary side of the equalization transformer is connected with the anode of the output rectifier diode, and the cathode of the output rectifier diode is connected with the first end of the output capacitor. As the equalization loop is separated from the external charging and discharging loop of the battery cell module, the battery cell modules which are mutually equalized can be equalized no matter in a standing state or a charging and discharging state, and the battery cell equalization circuit has the advantages of high equalization efficiency and good flexibility.

Description

Technical Field

[0001] The present disclosure relates to the field of battery technology, and in particular to a multi-battery pack balancing circuit and a battery pack series-parallel balancing system. Background Art

[0002] Lithium-ion batteries, as a clean energy source, are widely used in various fields. This brings with it varying demands for battery voltage platforms and capacities. In particular, in high-voltage, high-capacity applications, single batteries struggle to meet these demands and face high maintenance costs. Therefore, multi-battery systems have become a viable solution to these challenges. However, individual differences between cells can lead to imbalance during use, shortening their lifespan. Therefore, to maintain these differences within a safe range, multi-battery systems require balancing management.

[0003] Existing technologies often use active balancing methods that transfer power from high-voltage batteries to low-voltage batteries. For example, the currently published Chinese invention patent application: A Battery Array Balancing Circuit and Balancing Method (Patent No. CN108134426A) provides a balancing method that controls the switching tubes inside the single cells to select different power paths. It first stores part of the power of the high-voltage battery in an external energy storage element, and then transfers the power on the energy storage element to the low-voltage battery. The external energy storage element is used as a medium to transfer the energy of the high-voltage battery to the low-voltage battery, thereby achieving battery power balancing.

[0004] However, traditional balancing methods target battery cells rather than battery packs. Once a battery array is formed, it is difficult to change the number of cells in series or parallel. While the battery array can theoretically be expanded infinitely, each cell corresponds to a balancing module, each consisting of multiple switching transistors. Furthermore, balancing management of the battery system often relies on an external controller and balancing modules, resulting in limited flexibility. Utility Model Content

[0005] The purpose of the present disclosure is to overcome the deficiencies in the prior art and to provide a multi-battery pack balancing circuit and a battery pack series-parallel balancing system that effectively improve the balancing flexibility between battery modules.

[0006] The purpose of this disclosure is achieved through the following technical solutions:

[0007] A multi-battery pack balancing circuit comprises: a plurality of balancing sub-circuits; each of the balancing sub-circuits comprises a cell module, a balancing transformer, a primary-side electronic switch tube, a balancing positive-end switch, a balancing negative-end switch, an output rectifier diode and an output capacitor, wherein the plurality of battery packs are connected in series and / or in parallel with each other; the positive electrode of the cell module is connected to the second end of the primary side of the balancing transformer, the first end of the primary side of the balancing transformer is connected to the first end of the primary-side electronic switch tube, the second end of the primary-side electronic switch tube is connected to the negative electrode of the cell module, and the control end of the primary-side electronic switch tube is used to be connected to the first PWM control end of the balancing controller; the first end of the secondary side of the balancing transformer is connected to the positive electrode of the output rectifier diode, and the negative electrode of the output rectifier diode is connected to the output The first end of the capacitor is connected, the first end of the output capacitor is also connected to the first end of the output capacitor of other balancing sub-circuits, the second end of the output capacitor is connected to the second end of the secondary side of the balancing transformer, and the second end of the output capacitor is also connected to the second end of the output capacitor of other balancing sub-circuits; the positive pole of the battery cell module is also connected to the first end of the balancing positive end switch, the second end of the balancing positive end switch is connected to the first end of the output capacitor, and the control end of the balancing positive end switch is used to be connected to the positive end switch control end of the balancing controller; the negative pole of the battery cell module is also connected to the first end of the balancing negative end switch, the second end of the balancing negative end switch is connected to the second end of the output capacitor, and the control end of the balancing negative end switch is used to be connected to the negative end switch control end of the balancing controller.

[0008] In one embodiment, the balancing sub-circuit further includes a balancing current-sensing resistor, and the second end of the primary-side electronic switch tube is connected to the negative electrode of the battery module through the balancing current-sensing resistor.

[0009] In one embodiment, the balancing sub-circuit further includes a first feedback resistor and a second feedback resistor, the first end of the inductive side of the balancing transformer is connected to the first end of the first feedback resistor, the second end of the inductive side of the balancing transformer is connected to the negative electrode of the battery cell module, the second end of the first feedback resistor is connected to the negative electrode of the battery cell module through the second feedback resistor, and the second end of the first feedback resistor is used to connect to the balancing feedback detection end of the balancing controller.

[0010] In one embodiment, the balancing sub-circuit further includes a feedback diode, the first end of the inductive side of the balancing transformer is connected to the anode of the feedback diode, and the cathode of the feedback diode is connected to the first end of the first feedback resistor.

[0011] In one embodiment, the balancing sub-circuit further includes an absorption resistor and an absorption capacitor, the first end of the secondary side of the balancing transformer is connected to the first end of the absorption resistor, and the second end of the absorption resistor is connected to the cathode of the output rectifier diode through the absorption capacitor.

[0012] In one embodiment, the balanced positive-end switch includes a first positive-end electronic switch tube and a second positive-end electronic switch tube, the positive pole of the battery cell module is connected to the second end of the first positive-end electronic switch tube, the first end of the first positive-end electronic switch tube is connected to the first end of the second positive-end electronic switch tube, and the second end of the second positive-end electronic switch tube is connected to the first end of the output capacitor.

[0013] In one embodiment, the balanced negative-end switch includes a first negative-end electronic switch tube and a second negative-end electronic switch tube, the negative pole of the battery cell module is connected to the second end of the first negative-end electronic switch tube, the first end of the first negative-end electronic switch tube is connected to the first end of the second negative-end electronic switch tube, and the second end of the second negative-end electronic switch tube is connected to the second end of the output capacitor.

[0014] In one embodiment, the balancing sub-circuit further includes a clamping resistor and a clamping capacitor, the positive electrode of the battery cell module is connected to the first end of the clamping resistor and the first end of the clamping capacitor, respectively, and the second end of the clamping resistor and the second end of the clamping capacitor are both connected to the first end of the primary-side electronic switch tube.

[0015] In one embodiment, the balancing sub-circuit further includes a clamping diode, the first end of the primary-side electronic switch tube is connected to the anode of the clamping diode, and the cathode of the clamping diode is connected to the second end of the clamping resistor.

[0016] A battery pack series-parallel balancing system includes the multi-battery pack balancing circuit described in any one of the above embodiments.

[0017] Compared with the prior art, the present disclosure has at least the following advantages:

[0018] During balancing, the positive and negative balancing switches corresponding to the high-voltage battery packs in the two target balanced battery packs are closed, while the positive and negative balancing switches corresponding to the low-voltage battery packs in the two target balanced battery packs are turned on. By controlling the on / off control of the primary-side electronic switches corresponding to the high-voltage battery packs in the two target balanced battery packs, the low-voltage battery packs in the two target balanced battery packs simultaneously receive electrical energy from the secondary side of the transformer of the high-voltage battery packs in the two target balanced battery packs through their corresponding positive and negative balancing switches. Furthermore, because the balancing circuit is separated from the battery packs' external charge and discharge circuits, balancing can be performed between mutually balanced battery packs regardless of whether they are in a static or charging / discharging state, resulting in high balancing efficiency and flexibility. Furthermore, the balancing circuits of the two target balanced battery packs are connected via a transformer. Due to the transformer's isolation, the selection of the two target battery packs is not affected by their location in the battery system, enabling balancing between any two battery packs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0020] Figure 1 is a circuit diagram of a multi-battery pack balancing circuit in one embodiment;

[0021] Figure 2 for Figure 1 The circuit diagram of the balancing sub-circuit in the multi-battery pack balancing circuit is shown. DETAILED DESCRIPTION

[0022] To facilitate understanding of the present disclosure, a more comprehensive description of the present disclosure will be provided below with reference to the accompanying drawings. The accompanying drawings illustrate preferred embodiments of the present disclosure. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the disclosure.

[0023] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly attached to the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this disclosure pertains. The terms used herein in the specification of this disclosure are intended only to describe specific embodiments and are not intended to limit this disclosure. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0025] The present disclosure relates to a multi-battery pack balancing circuit. In one embodiment, the multi-battery pack balancing circuit includes multiple balancing sub-circuits; each of the balancing sub-circuits includes a cell module, a balancing transformer, a primary-side electronic switch tube, a balancing positive-end switch, a balancing negative-end switch, an output rectifier diode, and an output capacitor, wherein the multiple battery packs are connected in series and / or in parallel with each other; the positive electrode of the cell module is connected to the second end of the primary side of the balancing transformer, the first end of the primary side of the balancing transformer is connected to the first end of the primary-side electronic switch tube, the second end of the primary-side electronic switch tube is connected to the negative electrode of the cell module, and the control end of the primary-side electronic switch tube is used to be connected to the first PWM control end of the balancing controller; the first end of the secondary side of the balancing transformer is connected to the positive electrode of the output rectifier diode, and the negative electrode of the output rectifier diode is connected to the negative electrode of the cell module. The first end of the output capacitor is connected, and the first end of the output capacitor is also connected to the first end of the output capacitor of other balancing sub-circuits. The second end of the output capacitor is connected to the second end of the secondary side of the balancing transformer, and the second end of the output capacitor is also connected to the second end of the output capacitor of other balancing sub-circuits; the positive pole of the battery cell module is also connected to the first end of the balancing positive end switch, and the second end of the balancing positive end switch is connected to the first end of the output capacitor, and the control end of the balancing positive end switch is used to be connected to the positive end switch control end of the balancing controller; the negative pole of the battery cell module is also connected to the first end of the balancing negative end switch, and the second end of the balancing negative end switch is connected to the second end of the output capacitor, and the control end of the balancing negative end switch is used to be connected to the negative end switch control end of the balancing controller. During balancing, the balancing positive and negative switches corresponding to the high-voltage battery packs in the two target balancing battery packs are closed, while the balancing positive and negative switches corresponding to the low-voltage battery packs in the two target balancing battery packs are turned on. By controlling the on / off of the primary-side electronic switches corresponding to the high-voltage battery packs in the two target balancing battery packs, the electrical energy output from the secondary side of the high-voltage battery pack transformer is transmitted to the low-voltage battery pack via the balancing positive and negative switches of the low-voltage battery pack. Moreover, since the balancing circuit is separated from the external charge and discharge circuits of the cell module, balancing can be performed between mutually balanced cell modules regardless of whether they are in a static state or in a charge and discharge state, which has the advantages of high balancing efficiency and good flexibility. In addition, the balancing circuits of the two target balancing cell modules are connected through a transformer. Due to the isolation effect of the transformer, the selection of the two target cell modules is not affected by the location of the cell modules in the battery system, thus achieving balancing between any two cell modules.

[0026] See also Figure 1 , which is a circuit diagram of a multi-battery pack balancing circuit according to an embodiment of the present disclosure.

[0027] The multi-battery pack balancing circuit 10 of one embodiment includes multiple balancing sub-circuits. Figure 2 Each balancing subcircuit includes a cell module, a balancing transformer T1, a primary-side electronic switch Q1, a balancing positive-end switch, a balancing negative-end switch, an output rectifier diode D2, and an output capacitor C2. Multiple battery packs are connected in series and / or in parallel. The positive electrode P+ of the cell module is connected to the second terminal of the primary side of the balancing transformer T1. The first terminal of the primary side of the balancing transformer T1 is connected to the first terminal of the primary-side electronic switch Q1. The second terminal of the primary-side electronic switch Q1 is connected to the negative electrode P- of the cell module. The control terminal of the primary-side electronic switch Q1 is used to connect to the first PWM control terminal of the balancing controller. The first terminal of the secondary side of the balancing transformer T1 is connected to the positive electrode of the output rectifier diode D2, and the negative electrode of the output rectifier diode D2 is connected to the first terminal of the output capacitor C2. The first terminal of the output capacitor C2 is also connected to the first terminal of the output capacitor C2 of another balancing sub-circuit. The second terminal of the output capacitor C2 is connected to the second terminal of the secondary side of the balancing transformer T1, and the second terminal of the output capacitor C2 is also connected to the second terminal of the output capacitor C2 of another balancing sub-circuit. The positive terminal P+ of the cell module is also connected to the first terminal of the balancing positive switch, the second terminal of the balancing positive switch is connected to the first terminal of the output capacitor C2, and the control terminal of the balancing positive switch is used to connect to the positive switch control terminal of the balancing controller. The negative terminal P- of the cell module is also connected to the first terminal of the balancing negative switch, the second terminal of the balancing negative switch is connected to the second terminal of the output capacitor C2, and the control terminal of the balancing negative switch is used to connect to the negative switch control terminal of the balancing controller.

[0028] In this embodiment, during balancing, the positive and negative balancing switches corresponding to the high-voltage battery packs in the two target balancing battery packs are closed, while the positive and negative balancing switches corresponding to the low-voltage battery packs in the two target balancing battery packs are closed. By controlling the on / off control of the primary-side electronic switches Q1 corresponding to the high-voltage battery packs in the two target balancing battery packs, the power output from the secondary side of the transformer of the high-voltage battery pack is transmitted to the low-voltage battery pack via the positive and negative balancing switches of the low-voltage battery packs. Furthermore, because the balancing circuit is separated from the external charge and discharge circuits of the battery packs, balancing can be performed between the mutually balancing battery packs, regardless of whether they are in a static state or in a charge or discharge state. This provides the advantages of high balancing efficiency and excellent flexibility. Furthermore, the balancing circuits of the two target balancing battery packs are connected via a transformer. Due to the isolation provided by the transformer, the selection of the two target battery packs is not affected by their location in the battery system, enabling balancing between any two battery packs. Moreover, during balancing, the balancing positive switch and the balancing negative switch of the low-voltage battery pack are continuously turned on, which is equivalent to the positive and negative poles of the low-voltage battery pack cells being directly connected to the output end of the high-voltage battery pack switching power supply, and the energy output by the transformer is directly used to charge the low-voltage battery pack.

[0029] In another embodiment, each of the battery packs includes the multi-battery pack balancing circuit, that is, each battery pack includes a cell module and a balancing circuit.

[0030] In another embodiment, the primary-side electronic switch tube Q1 is an N-type MOS tube, the first end of the primary-side electronic switch tube Q1 is the drain of the N-type MOS tube, the second end of the primary-side electronic switch tube Q1 is the source of the N-type MOS tube, and the control end of the primary-side electronic switch tube Q1 is the gate of the N-type MOS tube.

[0031] In one embodiment, see Figure 2 The balancing sub-circuit further includes a balancing current-sensing resistor R2, through which the second end of the primary-side electronic switch Q1 is connected to the negative electrode P- of the cell module. In this embodiment, the balancing current-sensing resistor R2 is connected in series with the second end of the primary-side electronic switch Q1. The balancing current-sensing resistor R2 serves as a resistor for detecting the current between the second end of the primary-side electronic switch Q1 and the negative electrode P- of the cell module. Specifically, the current-sensing end of the balancing controller is connected in parallel across the balancing current-sensing resistor R2. By collecting the voltage across the balancing current-sensing resistor R2, the current output by the high-voltage battery pack in the two target balanced battery packs during the balancing process can be determined.

[0032] In one embodiment, see Figure 2The balancing subcircuit also includes a low-voltage battery current-sensing resistor R6. The negative electrode of the cell module is connected to the first terminal of the balancing negative-end switch via the low-voltage battery current-sensing resistor R6. The detection terminal of the low-voltage battery current-sensing resistor R6 is connected to the low-voltage feedback terminal of the balancing controller. The low-voltage battery current-sensing resistor R6 is used to detect the balancing current output by the low-voltage battery packs in the two target balancing battery packs during the balancing process.

[0033] In one embodiment, see Figure 2 The balancing sub-circuit also includes a first feedback resistor R5 and a second feedback resistor R4. The first end of the sensing side of the balancing transformer T1 is connected to the first end of the first feedback resistor R5, and the second end of the sensing side of the balancing transformer T1 is connected to the negative electrode of the cell module. The second end of the first feedback resistor R5 is connected to the negative electrode of the cell module through the second feedback resistor R4. The second end of the first feedback resistor R5 is used to connect to the balanced feedback detection terminal of the balancing controller. In this embodiment, the first feedback resistor R5 and the second feedback resistor R4 are connected in series on the sensing side of the balancing transformer T1. The sensing side of the balancing transformer T1 serves as the feedback side for balanced electric energy. The first feedback resistor R5 and the second feedback resistor R4 form a voltage divider feedback circuit, which facilitates proportional feedback detection of the output voltage of the sensing side of the balancing transformer T1, thereby improving the detection accuracy of the balanced voltage and current of the cell module.

[0034] In another embodiment, the primary side first end, the secondary side first end and the inductive side first end of the balancing transformer are like-named ends, and the primary side second end, the secondary side second end and the inductive side second end of the balancing transformer are different-named ends.

[0035] Furthermore, the balancing subcircuit also includes a feedback diode D3. The first end of the sensing side of the balancing transformer T1 is connected to the anode of the feedback diode D3, and the cathode of the feedback diode D3 is connected to the first end of the first feedback resistor R5. In this embodiment, when the primary-side electronic switch Q1 is on, the feedback diode D3 is reverse biased, so that the electrical energy output by the battery module is stored in the primary side of the balancing transformer T1. When the primary-side electronic switch Q1 is off, the sensing side of the balancing transformer T1 receives feedback, facilitating monitoring of the balancing operation status.

[0036] In another embodiment, the output rectifier diode D2 functions similarly to the feedback diode D3. When the primary-side electronic switch Q1 is on, the output rectifier diode D2 is also reverse-biased. When the primary-side electronic switch Q1 is off, the output rectifier diode D2 is forward-biased, facilitating the output of electrical energy from the primary side of the balancing transformer T1 to the output capacitor C2. Furthermore, this energy is transmitted to the load (i.e., the low-voltage battery pack in the target balancing battery pack) via the output capacitor, while simultaneously charging the output capacitor. In the next cycle, the output rectifier diode D2 is reverse-biased, and the output current is provided by the output capacitor, resulting in a DC power supply.

[0037] In one embodiment, see Figure 2 The balancing subcircuit further includes an absorption resistor R3 and an absorption capacitor C3. The first end of the secondary side of the balancing transformer T1 is connected to the first end of the absorption resistor R3, and the second end of the absorption resistor R3 is connected to the cathode of the output rectifier diode D2 via the absorption capacitor C3. In this embodiment, the absorption resistor R3 and the absorption capacitor C3 are connected in series to form an absorption circuit for the secondary side of the balancing transformer T1, which absorbs pulses, improves output stability, and reduces radiation.

[0038] In one embodiment, see Figure 2 The balanced positive-end switch includes a first positive-end electronic switch tube Q2 and a second positive-end electronic switch tube Q3. The positive electrode P+ of the battery cell module is connected to the second end of the first positive-end electronic switch tube Q2, the first end of the first positive-end electronic switch tube Q2 is connected to the first end of the second positive-end electronic switch tube Q3, and the second end of the second positive-end electronic switch tube Q3 is connected to the first end of the output capacitor C2. In this embodiment, the first positive-end electronic switch tube Q2 and the second positive-end electronic switch tube Q3 are P-type MOS transistors. The first end of the first positive-end electronic switch tube Q2 and the first end of the second positive-end electronic switch tube Q3 serve as drains of the P-type MOS transistors, the second end of the first positive-end electronic switch tube Q2 and the second end of the second positive-end electronic switch tube Q3 serve as sources of the P-type MOS transistors, and the control end of the first positive-end electronic switch tube Q2 and the control end of the second positive-end electronic switch tube Q3 serve as gates of the P-type MOS transistors. By connecting the first positive-end electronic switch tube Q2 and the second positive-end electronic switch tube Q3 in reverse series, it is convenient to perform charge and discharge balance control on the positive end of the battery cell module.

[0039] In one embodiment, see Figure 2The balanced negative-end switch includes a first negative-end electronic switch tube Q4 and a second negative-end electronic switch tube Q5. The negative electrode P- of the battery cell module is connected to the second end of the first negative-end electronic switch tube Q4, the first end of the first negative-end electronic switch tube Q4 is connected to the first end of the second negative-end electronic switch tube Q5, and the second end of the second negative-end electronic switch tube Q5 is connected to the second end of the output capacitor C2. In this embodiment, the first negative-end electronic switch tube Q4 and the second negative-end electronic switch tube Q5 are P-type MOS tubes. The first end of the first negative-end electronic switch tube Q4 and the first end of the second negative-end electronic switch tube Q5 serve as the drain of the P-type MOS tube, the second end of the first negative-end electronic switch tube Q4 and the second end of the second negative-end electronic switch tube Q5 serve as the source of the P-type MOS tube, and the control end of the first negative-end electronic switch tube Q4 and the control end of the second negative-end electronic switch tube Q5 serve as the gate of the P-type MOS tube. By connecting the first negative-end electronic switch tube Q4 and the second negative-end electronic switch tube Q5 in reverse series, it is convenient to perform charge and discharge balance control on the negative end of the battery cell module.

[0040] In another embodiment, after two battery packs receive a balancing instruction sent by the master battery pack: for the high-voltage battery pack in the two target balancing battery packs, a control voltage is output through the positive switch control terminal and the negative switch control terminal of the balancing controller, so that the first positive electronic switch tube Q2, the second positive electronic switch tube Q3, the first negative electronic switch tube Q4, and the second negative electronic switch tube Q5 are turned off. At the same time, the balancing controller outputs a PWM drive signal to the primary-side electronic switch tube Q1. When the primary-side electronic switch tube Q1 is turned on, the battery charges the primary coil and stores energy. Since the output rectifier diode D2 and the feedback diode D3 are reverse biased, no current flows through the secondary coil. When the primary-side electronic switch Q1 is turned off, the polarity of the primary coil is reversed, the output rectifier diode D2 and the feedback diode D3 are forward biased, and the energy stored in the primary is output to the load through the output rectifier diode D2, that is, to the high-voltage battery pack in the two target balanced battery packs, while charging the output capacitor C2. On the other side, the transformer output voltage is fed back to the balancing controller through the feedback diode D3, the first feedback resistor R5, and the second feedback resistor R4. When the primary-side electronic switch Q1 is turned on again, the output rectifier diode D2 is reverse biased, the primary coil stores energy, the secondary coil has no current, and the energy required by the load is provided by the output capacitor C2, and the cycle continues. During the switching process, the balancing controller detects the current and output voltage through the balancing current detection resistor R2, the feedback diode D3, the first feedback resistor R5, and the second feedback resistor R4. According to the above values, it adjusts the duty cycle of the PWM signal driven by the primary-side electronic switch Q1, thereby adjusting the voltage and current at the output end.

[0041] For the low-voltage battery packs in the two target balancing battery packs, the primary-side electronic switch tube Q1 of the low-voltage battery packs in the two target balancing battery packs is turned off, that is, the switching power supply circuit portion of the low-voltage battery packs in the two target balancing battery packs is inoperative. The positive and negative switch control terminals of the balancing controllers corresponding to the low-voltage battery packs in the two target balancing battery packs output a control voltage, causing the first positive electronic switch tube Q2, the second positive electronic switch tube Q3, the first negative electronic switch tube Q4, and the second negative electronic switch tube Q5 of the low-voltage battery packs in the two target balancing battery packs to conduct. At this time, the total positive electrode of the battery cells is connected to the positive terminal of the secondary output coil of the high-voltage battery pack in the two target balancing battery packs via the balancing positive line, and the total negative electrode of the battery cells is connected to the negative terminal of the secondary output coil of the high-voltage battery pack in the two target balancing battery packs via the balancing negative line. At this time, because the output voltage of the high-voltage battery pack in the two target balancing battery packs is greater than that of the low-voltage battery pack in the two target balancing battery packs, electrical energy is transferred from the high-voltage battery pack in the two target balancing battery packs to the low-voltage battery pack in the two target balancing battery packs. For other non-target cell modules in the battery system, the above-mentioned switch MOS tubes remain in the closed state, so that only two target cell modules to be balanced form a conductive loop on the balancing loop.

[0042] In one embodiment, see Figure 2 The balancing sub-circuit further includes a clamping resistor R1 and a clamping capacitor C1. The positive electrode P+ of the cell module is connected to the first end of the clamping resistor R1 and the first end of the clamping capacitor C1, respectively. The second end of the clamping resistor R1 and the second end of the clamping capacitor C1 are both connected to the first end of the primary-side electronic switch Q1. In this embodiment, the clamping resistor R1 and the clamping capacitor C1 are simultaneously connected in parallel on the primary side of the balancing transformer T1. The clamping resistor R1 and the clamping capacitor C1 are connected in parallel to form a clamping circuit on the primary side of the balancing transformer T1 to absorb the leakage inductance of the primary side of the balancing transformer T1, thereby reducing the peak voltage across the drain and source of the primary-side electronic switch Q1 during the switching process, thereby effectively protecting the primary-side electronic switch Q1 and ensuring the normal operation of the primary-side electronic switch Q1. The balancing subcircuit also includes a clamping diode D1. The first end of the primary-side electronic switch Q1 is connected to the anode of the clamping diode D1, and the cathode of the clamping diode D1 is connected to the second end of the clamping resistor R1. In this embodiment, the clamping diode D1 is connected in series between the first end of the primary side of the balancing transformer T1 and the clamping capacitor C1. This allows the clamping resistor R1, the clamping capacitor C1, and the clamping diode D1 to form an RCD clamping circuit, further effectively protecting the primary-side electronic switch Q1.

[0043] In one embodiment, the present disclosure also relates to a battery module series-parallel balancing system, including the multi-battery module balancing circuit described in any of the above embodiments. In this embodiment, the multi-battery module balancing circuit includes multiple balancing sub-circuits; each of the balancing sub-circuits includes a battery module, a balancing transformer, a primary-side electronic switch tube, a balancing positive-end switch, a balancing negative-end switch, an output rectifier diode, and an output capacitor, wherein the multiple battery modules are connected in series and / or in parallel with each other; the positive electrode of the battery module is connected to the second end of the primary side of the balancing transformer, the first end of the primary side of the balancing transformer is connected to the first end of the primary-side electronic switch tube, the second end of the primary-side electronic switch tube is connected to the negative electrode of the battery module, and the control end of the primary-side electronic switch tube is used to be connected to the first PWM control end of the balancing controller; the first end of the secondary side of the balancing transformer is connected to the positive electrode of the output rectifier diode, and the negative electrode of the output rectifier diode is connected to the negative electrode of the battery module. The first end of the output capacitor is connected, and the first end of the output capacitor is also connected to the first end of the output capacitor of other balancing sub-circuits. The second end of the output capacitor is connected to the second end of the secondary side of the balancing transformer, and the second end of the output capacitor is also connected to the second end of the output capacitor of other balancing sub-circuits; the positive pole of the battery cell module is also connected to the first end of the balancing positive end switch, and the second end of the balancing positive end switch is connected to the first end of the output capacitor, and the control end of the balancing positive end switch is used to be connected to the positive end switch control end of the balancing controller; the negative pole of the battery cell module is also connected to the first end of the balancing negative end switch, and the second end of the balancing negative end switch is connected to the second end of the output capacitor, and the control end of the balancing negative end switch is used to be connected to the negative end switch control end of the balancing controller. During balancing, the positive and negative balancing switches corresponding to the high-voltage battery packs in the two target balancing battery packs are closed, while the positive and negative balancing switches corresponding to the low-voltage battery packs in the two target balancing battery packs are turned on. By controlling the on / off control of the primary-side electronic switches corresponding to the high-voltage battery packs in the two target balancing battery packs, the electrical energy in the high-voltage battery packs in the two target balancing battery packs is stored in the corresponding output capacitors. The low-voltage battery packs in the two target balancing battery packs then receive the electrical energy from the output capacitors corresponding to the high-voltage battery packs in the two target balancing battery packs via their corresponding positive and negative balancing switches. Furthermore, because the balancing circuit is separated from the external charge and discharge circuits of the cell modules, balancing can be performed between mutually balanced cell modules, regardless of whether they are in a static state or in a charge or discharge state. This provides the advantages of high balancing efficiency and excellent flexibility. Furthermore, the balancing circuits of the two target balancing cell modules are connected via a transformer. Due to the isolation provided by the transformer, the selection of the two target cell modules is not affected by their location in the battery system, enabling balancing between any two cell modules.

[0044] The above-described embodiments merely represent several implementation methods of the present disclosure. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the scope of the present disclosure, all of which fall within the scope of protection of the present disclosure. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A multi-battery pack balancing circuit, characterized in that: include: multiple equalization sub-circuits; Each of the balancing sub-circuits includes a cell module, a balancing transformer, a primary-side electronic switch tube, a balancing positive-end switch, a balancing negative-end switch, an output rectifier diode, and an output capacitor, wherein multiple battery packs are connected in series and / or in parallel. The positive electrode of the battery cell module is connected to the second end of the primary side of the balancing transformer, the first end of the primary side of the balancing transformer is connected to the first end of the primary side electronic switch tube, the second end of the primary side electronic switch tube is connected to the negative electrode of the battery cell module, and the control end of the primary side electronic switch tube is used to be connected to the first PWM control end of the balancing controller; the first end of the secondary side of the balancing transformer is connected to the positive electrode of the output rectifier diode, the negative electrode of the output rectifier diode is connected to the first end of the output capacitor, the first end of the output capacitor is also connected to the first end of the output capacitor of other balancing sub-circuits, the second end of the output capacitor is connected to the second end of the secondary side of the balancing transformer, and the second end of the output capacitor is also connected to the second end of the output capacitor of other balancing sub-circuits; The positive pole of the battery cell module is also connected to the first end of the balanced positive end switch, the second end of the balanced positive end switch is connected to the first end of the output capacitor, and the control end of the balanced positive end switch is used to be connected to the positive end switch control end of the balanced controller; the negative pole of the battery cell module is also connected to the first end of the balanced negative end switch, the second end of the balanced negative end switch is connected to the second end of the output capacitor, and the control end of the balanced negative end switch is used to be connected to the negative end switch control end of the balanced controller.

2. The multi-battery pack balancing circuit according to claim 1, characterized in that: The balancing sub-circuit further includes a balancing current-sensing resistor, and the second end of the primary-side electronic switch tube is connected to the negative electrode of the battery module through the balancing current-sensing resistor.

3. The multi-battery pack balancing circuit according to claim 1, characterized in that: The balancing sub-circuit also includes a first feedback resistor and a second feedback resistor. The first end of the inductive side of the balancing transformer is connected to the first end of the first feedback resistor, the second end of the inductive side of the balancing transformer is connected to the negative electrode of the battery cell module, the second end of the first feedback resistor is connected to the negative electrode of the battery cell module through the second feedback resistor, and the second end of the first feedback resistor is used to be connected to the balancing feedback detection end of the balancing controller.

4. The multi-battery pack balancing circuit according to claim 3, characterized in that: The balancing sub-circuit further includes a feedback diode. The first end of the inductive side of the balancing transformer is connected to the anode of the feedback diode, and the cathode of the feedback diode is connected to the first end of the first feedback resistor.

5. The multi-battery pack balancing circuit according to claim 1, characterized in that: The balancing subcircuit further includes an absorption resistor and an absorption capacitor. The first end of the secondary side of the balancing transformer is connected to the first end of the absorption resistor, and the second end of the absorption resistor is connected to the cathode of the output rectifier diode through the absorption capacitor.

6. The multi-battery pack balancing circuit according to claim 1, characterized in that: The balanced positive-end switch includes a first positive-end electronic switch tube and a second positive-end electronic switch tube. The positive pole of the battery cell module is connected to the second end of the first positive-end electronic switch tube, the first end of the first positive-end electronic switch tube is connected to the first end of the second positive-end electronic switch tube, and the second end of the second positive-end electronic switch tube is connected to the first end of the output capacitor.

7. The multi-battery pack balancing circuit according to claim 1, characterized in that: The balanced negative-end switch includes a first negative-end electronic switch tube and a second negative-end electronic switch tube. The negative pole of the battery cell module is connected to the second end of the first negative-end electronic switch tube, the first end of the first negative-end electronic switch tube is connected to the first end of the second negative-end electronic switch tube, and the second end of the second negative-end electronic switch tube is connected to the second end of the output capacitor.

8. The multi-battery pack balancing circuit according to claim 1, characterized in that: The balancing sub-circuit also includes a clamping resistor and a clamping capacitor. The positive electrode of the battery cell module is connected to the first end of the clamping resistor and the first end of the clamping capacitor, respectively. The second end of the clamping resistor and the second end of the clamping capacitor are both connected to the first end of the primary-side electronic switch tube.

9. The multi-battery pack balancing circuit according to claim 8, characterized in that: The balancing sub-circuit also includes a clamping diode, the first end of the primary-side electronic switch tube is connected to the positive electrode of the clamping diode, and the negative electrode of the clamping diode is connected to the second end of the clamping resistor; and / or, the balancing sub-circuit also includes a low-voltage battery current-sensing resistor, the negative electrode of the battery cell module is connected to the first end of the balancing negative-end switch through the low-voltage battery current-sensing resistor, and the detection end of the low-voltage battery current-sensing resistor is connected to the low-voltage feedback end of the balancing controller.

10. A battery pack series-parallel balancing system, characterized in that: The multi-battery pack balancing circuit comprises the multi-battery pack balancing circuit according to any one of claims 1 to 9.

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