Charging current limiting circuit for parallel operation of battery pack

Abstract

The utility model relates to the technical field of electronic circuits, and particularly discloses a charging current-limiting circuit for parallel operation of a battery pack, which comprises a battery module, a discharging MOS (Metal Oxide Semiconductor) tube, a charging MOS tube, a switch module, an MCU (Microprogrammed Control Unit) control module, an AFE module and a charging current-limiting module, the positive electrode of the battery module is connected in series with the discharging MOS tube and the charging MOS tube, and the switch module is connected in parallel with the charging MOS tube; the signal control end of the MCU control module is connected with the input end of the AFE module. The output end of the AFE module is connected with the controlled end of the discharging MOS tube and the controlled end of the charging MOS tube. The logic control end of the MCU control module is connected with the input end of the charging current-limiting module, and the output end of the charging current-limiting module is connected with the controlled end of the switch module; according to the utility model, the requirement of charging current limiting in a parallel operation function use scene can be met, the capacity of the battery pack can be utilized to the maximum extent, the service life of the battery pack can be prolonged, and the use safety can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of electronic circuits, in particular to a charging current limiting circuit for parallel connection of battery packs. Background Art

[0002] At present, in order to facilitate capacity expansion, low-voltage household energy storage systems often encounter the situation of multiple battery packs being used in parallel, which may range from 2 to 15 groups. Since the actual capacity parameters of each battery pack are different, in practical applications, it is inevitable that the voltages of each battery pack are uneven. If there is no protection strategy and the systems are directly connected in parallel, the two battery packs will charge each other. At this time, the charging current is uncontrollable, and there will be a great risk of damage to the battery pack or even explosion due to excessive charging current, which will reduce the life of the battery pack and pose a safety hazard. Utility Model Content

[0003] In response to the above-mentioned problems of uncontrollable charging current, reduced battery pack life and potential safety hazards, the utility model provides a charging current limiting circuit for parallel connection of battery packs, which can solve the demand for charging current limiting when the parallel function is used, so that the capacity of the battery pack can be utilized to the maximum extent, while extending the service life of the battery pack and improving its safety of use.

[0004] In order to solve the above technical problems, the specific solutions provided by the utility model are as follows:

[0005] A charging current limiting circuit for parallel connection of a battery pack, comprising a battery module, a discharge MOS tube, a charging MOS tube, a switch module, an MCU control module, an AFE module and a charging current limiting module;

[0006] The positive electrode of the battery module is connected in series with the discharge MOS tube and the charge MOS tube, and the switch module is connected in parallel with the charge MOS tube;

[0007] The signal control end of the MCU control module is connected to the input end of the AFE module, and the output end of the AFE module is connected to the controlled ends of the discharge MOS tube and the charge MOS tube;

[0008] The logic control end of the MCU control module is connected to the input end of the charging current limiting module, and the output end of the charging current limiting module is connected to the controlled end of the switch module.

[0009] In some embodiments, the switch module includes a first electronic switch tube, a first resistor, a first diode, a first capacitor, a second capacitor and a first inductor;

[0010] The first end of the first electronic switch tube is connected to the first end of the first diode and the first end of the first inductor, and the second end of the first inductor is connected to the first end of the charging MOS tube;

[0011] The second end of the first electronic switch tube is connected to the first end of the first resistor, and the second end of the first resistor is connected to the second end of the charging MOS tube;

[0012] The first end of the first capacitor is connected to the second end of the first inductor, the first end of the second capacitor is connected to the second end of the first resistor, and the second ends of the first capacitor and the second capacitor are connected to the second end of the first diode, so as to cooperate with the charging current limiting module to achieve the purpose of charging current limitation and solve the need for charging current limitation in the use scenario of the parallel function.

[0013] In some embodiments, the charging current limiting module includes a DC-DC power supply unit, a PWM pulse width modulation unit and a BUCK unit;

[0014] The input end of the DC-DC power supply unit is connected to the logic control end of the MCU control module, the output end of the DC-DC power supply unit is connected to the input end of the PWM pulse width modulation unit, the output end of the PWM pulse width modulation unit is connected to the input end of the BUCK unit, the output end of the BUCK unit is connected to the controlled end of the switch module, the DC-DC power supply unit is used to output a stable voltage to the PWM pulse width modulation unit and the BUCK unit, the PWM pulse width modulation unit outputs a modulated PWM waveform, and the BUCK unit is used to control the conduction and disconnection of the switch module, thereby achieving the purpose of completing the charging current limitation.

[0015] In some embodiments, the DC-DC power supply unit includes a power switch circuit and a step-down circuit, the controlled end of the power switch circuit is connected to the logic control end of the MCU control module, the first end of the power switch circuit is connected to the power supply, the second end of the power switch circuit is connected to the input end of the step-down circuit, the output end of the step-down circuit is connected to the input end of the PWM pulse width modulation unit, the power switch circuit is turned on under the control of the output signal of the logic control end of the MCU control module, and the step-down voltage is used to output a stable voltage.

[0016] In some embodiments, the power switch circuit includes a second electronic switch tube and a third electronic switch tube, the controlled end of the second electronic switch tube is connected to the logic control end of the MCU control module, the first end of the second electronic switch tube is connected to the controlled end of the third electronic switch tube, and the second end of the second electronic switch tube is grounded;

[0017] The first end of the third electronic switch tube is connected to a power supply, and the second end of the third electronic switch tube is connected to an input end of the step-down circuit.

[0018] In some embodiments, the second electronic switch tube and the third electronic switch tube are both MOS tubes. Using MOS tubes in power switch circuits has the advantages of great design flexibility, low power consumption, stable performance, etc.

[0019] In some embodiments, the PWM pulse width modulation unit includes a TL494 chip, the second pin of the TL494 chip is connected to a second resistor and a third resistor, the fourteenth pin of the TL494 chip is used to output voltage and passes through the second resistor and the third resistor respectively, so that the second pin of the TL494 chip obtains a reference voltage to achieve modulation and output of the PWM waveform.

[0020] In some embodiments, the BUCK unit includes an input signal switch circuit, a driver chip, a first output signal switch circuit, a second output signal switch circuit, and a detection resistor;

[0021] The controlled end of the input signal switch circuit is connected to the ninth pin of the TL494 chip, the first end of the input signal switch circuit is connected to the input end of the driver chip, the first output end of the driver chip is connected to the controlled end of the first output signal switch circuit, the second output end of the driver chip is connected to the controlled end of the second output signal switch circuit, the first end of the detection resistor is connected to the first end of the first output signal switch circuit and the first pin of the PWM pulse width modulation unit, and the reference voltage is combined with the charging current flowing through the detection resistor to modulate the PWM waveform, so as to limit the positive charging current of the battery module to a set value.

[0022] In some embodiments, the first output signal switching circuit includes a fourth electronic switch tube, a controlled end of the fourth electronic switch tube is connected to the first output end of the driver chip, and the second output signal switching circuit includes a fifth electronic switch tube, a controlled end of the fifth electronic switch tube is connected to the second output end of the driver chip, and the fourth electronic switch tube and the fifth electronic switch tube are connected in parallel.

[0023] In some implementations, the driver chip is of type IR4427, and the IR4427 driver chip is a common-phase driver chip, so that the TL494 chip is used to provide the IR4427 driver chip to indirectly control the operation of the fourth electronic switch tube and the fifth electronic switch tube.

[0024] Compared with the prior art, the beneficial effect of the utility model is that: the utility model provides a charging current limiting circuit for parallel connection of battery packs, which controls the charging current of the battery pack after parallel connection by setting a charging current limiting module, so that the charging current is limited within a certain range, which can not only maximize the capacity of the entire battery pack, but also extend the service life of the battery pack and improve the safety of use. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of a charging current limiting circuit for parallel connection of battery packs provided in the first embodiment of the utility model;

[0026] Figure 2 This is a schematic diagram of the parallel application provided in the first embodiment of the present utility model;

[0027] Figure 3 This is a schematic diagram of the switch module provided in the second embodiment of the present utility model;

[0028] Figure 4 This is a schematic diagram of a charging current limiting module provided in Embodiment 3 of the present utility model;

[0029] Figure 5 This is a schematic diagram of a DC-DC power supply unit provided in Embodiment 3 of the present utility model;

[0030] Figure 6 This is a schematic diagram of a PWM pulse width modulation unit provided in Embodiment 4 of the present utility model;

[0031] Figure 7 This is a schematic diagram of the BUCK unit provided in the fourth embodiment of the present utility model;

[0032] 10- switch module;

[0033] 20-MCU control module;

[0034] 30-AFE module;

[0035] 40 - charging current limiting module; 41 - DC-DC power supply unit; 410 - power switch circuit; 411 - step-down circuit; 42 - PWM pulse width modulation unit; 43 - BUCK unit. DETAILED DESCRIPTION

[0036] The preferred embodiments of the present application are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present application can be more easily understood by those skilled in the art, thereby making a clearer definition of the protection scope of the present application.

[0037] The following description is based on the illustrated specific embodiments of the present application, which should not be considered as limiting other specific embodiments of the present application that are not described in detail herein.

[0038] For example, a charging current limiting circuit for parallel connection of a battery pack includes a battery module, a discharge MOS tube, a charge MOS tube, a switch module, an MCU control module, an AFE module and a charging current limiting module; the positive electrode of the battery module is connected in series with the discharge MOS tube and the charge MOS tube, and the switch module is connected in parallel with the charge MOS tube; the signal control end of the MCU control module is connected to the input end of the AFE module, and the output end of the AFE module is connected to the controlled ends of the discharge MOS tube and the charge MOS tube; the logic control end of the MCU control module is connected to the input end of the charge current limiting module, and the output end of the charge current limiting module is connected to the controlled end of the switch module.

[0039] The present embodiment provides a charging current limiting circuit for parallel connection of battery packs. By setting a charging current limiting module, the charging current of the battery pack after parallel connection is controlled so that the charging current is limited within a certain range. This can not only maximize the capacity of the entire battery pack, but also extend the service life of the battery pack and improve the safety of use.

[0040] Embodiment 1:

[0041] like Figure 1 and Figure 2 As shown, a charging current limiting circuit for parallel connection of battery packs is used to limit the charging current of the battery module when the battery packs are connected in parallel, including a battery module, a discharge MOS tube M1, a charging MOS tube M2, a switch module 10, an MCU control module 20, an AFE module 30 and a charging current limiting module 40.

[0042] Among them, the positive electrode of the battery module is connected in series with the discharge MOS tube M1 and the charging MOS tube M2, and the switch module 10 is connected in parallel with the charging MOS tube M2; the signal control end of the MCU control module 20 is connected to the input end of the AFE module 30, and the output end of the AFE module 30 is connected to the controlled ends of the discharge MOS tube M1 and the charging MOS tube M2; the logic control end of the MCU control module 20 is connected to the input end of the charging current limiting module 40, and the output end of the charging current limiting module 40 is connected to the controlled end of the switch module 10.

[0043] During parallel operation, different battery packs are connected. For ease of understanding, it is assumed here that battery pack 1 and battery pack 2 are operated in parallel, and battery pack 1 and battery pack 2 are two lithium-ion battery packs of the same type and with the same number of strings of low voltage and high voltage respectively. After the user performs the parallel operation, the high-voltage battery 2 can charge the low-voltage battery pack 1 within the set current.

[0044] Specifically, switch devices S1 and S2 are provided between battery pack 1 and battery pack 2. Before parallel operation, the MCU control module 20 in battery pack 1 sends an instruction to the AFE module 30, and the discharge MOS tube M1 is turned off by the AFE module 30. Similarly, the discharge MOS tube M4 in battery pack 2 is turned off. By turning off the discharge MOS tube M1 and the discharge MOS tube M4, it is prevented that the direct parallel operation in the unclosed state will cause the large current impact of charging and discharging of the two battery packs to damage the battery module. After closing the switch devices S1 and S2, the MCU control module 20 in battery pack 1 sends an instruction to the charging current limiting module 40 to turn on the current limiting mode, and then sends an instruction to the AFE module 30, and the discharge MOS tube M1 is turned on by the AFE module 30. Similarly, the discharge MOS tube M4 in battery pack 2 is turned on. At this time, the charging current limiting module 40 controls the switch module 10 to switch frequently, and cooperates with other devices in the switch module 10 to achieve the purpose of limiting the charging current to the set value.

[0045] The steps of starting the current limiting mode are as follows: by turning off the charging MOS tube M2 in battery pack one and the charging MOS tube M3 in battery pack two, the MCU control module 20 sends an instruction to the charging current limiting module 40, and the charging current limiting module 40 controls the switch module 10 to switch frequently.

[0046] The current limiting mode can be turned on by sending an instruction through the MCU control module 20, or the current limiting mode can be turned on by the BMS in the battery pack when it completes parallel operation autonomously to prevent the risk of command control failure and failure to enter current limiting.

[0047] A charging current limiting circuit for parallel connection of battery packs is provided in this example. By setting a charging current limiting module 40, the charging current of the battery pack after parallel connection is controlled so that the charging current is limited within a certain range. This can not only maximize the capacity of the entire battery pack, but also extend the service life of the battery pack and improve the safety of use.

[0048] Embodiment 2:

[0049] refer to Figure 3 In this example, the switch module 10 includes a first electronic switch tube Q1, a first resistor R1, a first diode D1, a first capacitor C1, a second capacitor C2 and a first inductor L1. The first end of the first electronic switch tube Q1 is connected to the first end of the first diode D1 and the first end of the first inductor L1, and the second end of the first inductor L1 is connected to the first end of the charging MOS tube M2; the second end of the first electronic switch tube Q1 is connected to the first end of the first resistor R1, and the second end of the first resistor R1 is connected to the second end of the charging MOS tube M2; the first end of the first capacitor C1 is connected to the second end of the first inductor L1, the first end of the second capacitor C2 is connected to the second end of the first resistor R1, and the second ends of the first capacitor C1 and the second capacitor C2 are connected to the second end of the first diode D1.

[0050] The switch module 10 is composed of a first electronic switch tube Q1, a first resistor R1, a first diode D1, a first capacitor C1, a second capacitor C2 and a first inductor L1, and is used to cooperate with the charging current limiting module 40 to achieve the purpose of charging current limitation. Under the action of the charging current limiting module 40, the first electronic switch tube Q1 is frequently switched, and cooperates with the first resistor R1, the first diode D1, the first capacitor C1, the second capacitor C2 and the first inductor L1 to solve the need for charging current limiting in the scenario where the parallel function is used.

[0051] Embodiment three:

[0052] refer to Figure 4 and Figure 5 In this example, the charging current limiting module 40 includes a DC-DC power supply unit 41, a PWM pulse width modulation unit 42 and a BUCK unit 43; the input end of the DC-DC power supply unit 41 is connected to the logic control end of the MCU control module 20, the output end of the DC-DC power supply unit 41 is connected to the input end of the PWM pulse width modulation unit 42, the output end of the PWM pulse width modulation unit 42 is connected to the input end of the BUCK unit 43, and the output end of the BUCK unit 43 is connected to the controlled end of the switch module 10.

[0053] The DC-DC power supply unit 41 is used to output a stable voltage to the PWM pulse width modulation unit 42 and the BUCK unit 43. The PWM pulse width modulation unit 42 outputs a modulated PWM waveform. The BUCK unit 43 is used to control the on and off of the switch module 10, thereby achieving the purpose of limiting the charging current.

[0054] Specifically, the DC-DC power supply unit 41 includes a power switch circuit 410 and a step-down circuit 411. The controlled end of the power switch circuit 410 is connected to the logic control end of the MCU control module 20, the first end of the power switch circuit 410 is connected to the power supply, the second end of the power switch circuit 410 is connected to the input end of the step-down circuit 411, and the output end of the step-down circuit 411 is connected to the input end of the PWM pulse width modulation unit 42. The power switch circuit 410 is turned on under the control of the output signal of the logic control end of the MCU control module 20, and the step-down circuit 411 is used to output a stable voltage.

[0055] The power switch circuit 410 includes a second electronic switch tube Q18 and a third electronic switch tube Q17, wherein the controlled end of the second electronic switch tube Q18 is connected to the logic control end of the MCU control module 20, the first end of the second electronic switch tube Q18 is connected to the controlled end of the third electronic switch tube Q17, and the second end of the second electronic switch tube Q18 is grounded; the first end of the third electronic switch tube Q17 is connected to the power supply, and the second end of the third electronic switch tube Q17 is connected to the input end of the step-down circuit 411. Among them, the second electronic switch tube Q18 and the third electronic switch tube Q17 are both MOS tubes, and the use of MOS tubes in the power switch circuit 410 has the advantages of large design flexibility, low power consumption, stable performance, etc.

[0056] The DC-DC power supply unit 41 is responsible for providing a stable power supply for the PWM pulse width modulation unit 42 and the BUCK unit 43. The power switch circuit 410 is used to turn on after the MCU control module 20 outputs a high level. The buck circuit 411 includes a resistor R35, a capacitor C74, a capacitor C75, a chip U1, a diode D30, a resistor R58, a capacitor C58, a diode D28, an inductor L3, a capacitor C76 and a resistor R93, and is used to output a 12V stable voltage.

[0057] Embodiment 4:

[0058] refer to Figure 6 and Figure 7 In this example, the PWM pulse width modulation unit 42 includes a TL494 chip, the second pin of the TL494 chip is connected to the second resistor R115 and the third resistor R132, the fourteenth pin of the TL494 chip is used to output voltage and passes through the second resistor R115 and the third resistor R132 respectively, so that the second pin of the TL494 chip obtains a reference voltage to realize the modulation and output of the PWM waveform.

[0059] The BUCK unit 43 includes an input signal switch circuit, a driver chip U13, a first output signal switch circuit, a second output signal switch circuit and detection resistors R201-R213. The controlled end of the input signal switch circuit is connected to the ninth pin of the TL494 chip, the first end of the input signal switch circuit is connected to the input end of the driver chip U13, the first output end of the driver chip U13 is connected to the controlled end of the first output signal switch circuit, the second output end of the driver chip U13 is connected to the controlled end of the second output signal switch circuit, the first end of the detection resistors R201-R213 is connected to the first end of the first output signal switch circuit and the first pin of the PWM pulse width modulation unit 42, and the reference voltage is combined with the charging current flowing through the detection resistors R201-R213 to modulate the PWM waveform, so as to limit the positive charging current of the battery module to a set value.

[0060] Specifically, in the PWM pulse width modulation unit 42, the TL494 chip integrates all the functions required to construct a pulse width modulation switch circuit, wherein the first pin, the second pin, the fifteenth pin, and the sixteenth pin are connected to two error amplifiers in the chip, the 5V reference voltage output of the fourteenth pin passes through the second resistor R115 and the third resistor R132 respectively, so that the second pin obtains a reference voltage, that is, the set value of the charging current, and the first pin detects the charging current flowing through the detection resistors R201-R213. When the voltage corresponding to the charging current detected by the first pin is greater than the reference voltage of the second pin, the TL494 chip will reduce the duty cycle of the output PWM waveform until the voltages of the first pin and the second pin are equal. It can be seen that the set value of the charging current depends on the resistance value of the third resistor R132. If the voltage detected by the first pin is lower than the reference voltage of the second pin, the TL494 chip will increase the duty cycle of the output PWM waveform until the voltages of the first pin and the second pin are equal. The sixteenth pin is grounded and the fifteenth pin obtains the vref / 2 reference voltage, which means that when the charging current is lower than the set value, the initial duty cycle is 100%. The third pin is the output feedback pin, and the fourth pin is the dead zone voltage setting pin. 0-35V corresponds to 0-49% duty cycle. Grounding represents the lowest duty cycle can be 0%. The fifth and sixth pins are connected to capacitor C79 and resistor R125 to configure the oscillation frequency. The ninth and tenth pins VG output the modulated PWM waveform to limit the positive electrode of the battery module or PACK-input charging current to the set value.

[0061] The first output signal switching circuit includes a fourth electronic switch tube Q32, and the controlled end of the fourth electronic switch tube Q32 is connected to the first output end of the driver chip U13. The second output signal switching circuit includes a fifth electronic switch tube Q36, and the controlled end of the fifth electronic switch tube Q36 is connected to the second output end of the driver chip U13. The fourth electronic switch tube Q32 and the fifth electronic switch tube Q36 are connected in parallel.

[0062] The model of the driver chip is IR4427, and the IR4427 driver chip is a common-phase driver chip, which realizes the operation of indirectly controlling the fourth electronic switch tube and the fifth electronic switch tube by using the TL494 chip to provide the IR4427 driver chip.

[0063] The driver chip I R4427S is a dual-channel, low-voltage, high-speed power MOSFET and IGBT driver. The input and output are controlled in the same direction and can provide a wider control voltage output range. Because the ninth pin and the tenth pin of the TL494 chip, that is, the VG pin output pins, are the emitters of the two triodes, the driving capability of controlling the two MOS high-speed switches is insufficient and cannot guarantee the normal driving of the fourth electronic switch tube Q32 and the fifth electronic switch tube Q36 to be turned on and off, the driver chip I R4427S uses a voltage with stable power supply and output, that is, a stable voltage provided by the DC-DC power supply unit 41 to control the high-frequency switching of the fourth electronic switch tube Q32 and the fifth electronic switch tube Q36. The driver chip I R4427S is a common-phase driver, so when the VG pin of the TL494 chip outputs a high level to the driver chip I When the input ends of the A and B channels of R4427S are connected, the output ends of the A and B channels of the driver chip IR4427S will output a high level that can drive the fourth electronic switch tube Q32 and the fifth electronic switch tube Q36 to work. Similarly, when the VG pin of the TL494 chip outputs a low level, the output ends of the A and B channels of the driver chip I R4427S output a low level, thereby realizing the use of the VG pin of the TL494 chip to provide the driver chip I R4427S with indirect control of the fourth electronic switch tube Q32 and the fifth electronic switch tube Q36, thereby achieving the set working function of the circuit.

[0064] Among them, the diode D31, the MOS tube Q22, the resistor R158, the capacitor C86 and the diode D31 constitute an input signal switch circuit; the resistor R185, the resistor R180, the diode D34, the resistor R188 and the fourth electronic switch tube Q32 constitute a first output signal switch circuit; the resistor R134, the resistor R176, the diode D32, the resistor R192 and the fifth electronic switch tube Q36 constitute a second output signal switch circuit; the BUCK unit 43 also includes an inductor L4, capacitors C87, C88, C90 and C91 that play a filtering role to suppress ripple voltage, and a resistor R186 and a capacitor C92 that can filter out the peak voltage generated by the inductance characteristics, and diodes D35, D36, D37 and D38 that play a freewheeling role when the fourth electronic switch tube Q32 and the fifth electronic switch tube Q36 are turned off.

[0065] In summary, the utility model provides a charging current limiting circuit for parallel connection of battery packs. By setting a charging current limiting module, the charging current of the battery pack after parallel connection is controlled so that the charging current is limited within a certain range. This can not only maximize the capacity of the entire battery pack, but also extend the service life of the battery pack and improve the safety of use.

[0066] The term "module" as used herein may be a software or hardware object executed on the computing system. The different components, modules, engines, and services described herein may be implementation objects on the computing system. The apparatus and methods described herein may be implemented in software or in hardware, and all are within the scope of protection of this application.

[0067] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0068] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

Claims

1. A charging current limiting circuit for parallel connection of battery packs, characterized in that: It comprises a battery module, a discharge MOS tube, a charge MOS tube, a switch module (10), an MCU control module (20), an AFE module (30) and a charge current limiting module (40); The positive electrode of the battery module is connected in series with the discharge MOS tube and the charge MOS tube, and the switch module (10) is connected in parallel with the charge MOS tube; The signal control end of the MCU control module (20) is connected to the input end of the AFE module (30), and the output end of the AFE module (30) is connected to the controlled ends of the discharge MOS tube and the charge MOS tube; The logic control end of the MCU control module (20) is connected to the input end of the charging current limiting module (40), and the output end of the charging current limiting module (40) is connected to the controlled end of the switch module (10).

2. The charging current limiting circuit for parallel connection of battery packs according to claim 1, characterized in that: The switch module (10) comprises a first electronic switch tube, a first resistor, a first diode, a first capacitor, a second capacitor and a first inductor; The first end of the first electronic switch tube is connected to the first end of the first diode and the first end of the first inductor, and the second end of the first inductor is connected to the first end of the charging MOS tube; The second end of the first electronic switch tube is connected to the first end of the first resistor, and the second end of the first resistor is connected to the second end of the charging MOS tube; The first end of the first capacitor is connected to the second end of the first inductor, the first end of the second capacitor is connected to the second end of the first resistor, and the second ends of the first capacitor and the second capacitor are connected to the second end of the first diode.

3. The charging current limiting circuit for battery pack parallel operation according to claim 1, characterized in that: The charging current limiting module (40) comprises a DC-DC power supply unit (41), a PWM pulse width modulation unit (42) and a BUCK unit (43); The input end of the DC-DC power supply unit (41) is connected to the logic control end of the MCU control module (20), the output end of the DC-DC power supply unit (41) is connected to the input end of the PWM pulse width modulation unit (42), the output end of the PWM pulse width modulation unit (42) is connected to the input end of the BUCK unit (43), and the output end of the BUCK unit (43) is connected to the controlled end of the switch module (10).

4. The charging current limiting circuit for parallel connection of battery packs according to claim 3, characterized in that: The DC-DC power supply unit (41) comprises a power switch circuit (410) and a step-down circuit (411); a controlled end of the power switch circuit (410) is connected to a logic control end of the MCU control module (20); a first end of the power switch circuit (410) is connected to a power source; a second end of the power switch circuit (410) is connected to an input end of the step-down circuit (411); and an output end of the step-down circuit (411) is connected to an input end of the PWM pulse width modulation unit (42).

5. The charging current limiting circuit for parallel connection of battery packs according to claim 4, characterized in that: The power switch circuit (410) comprises a second electronic switch tube and a third electronic switch tube, the controlled end of the second electronic switch tube is connected to the logic control end of the MCU control module (20), the first end of the second electronic switch tube is connected to the controlled end of the third electronic switch tube, and the second end of the second electronic switch tube is grounded; The first end of the third electronic switch tube is connected to a power source, and the second end of the third electronic switch tube is connected to an input end of the step-down circuit (411).

6. The charging current limiting circuit for parallel connection of battery packs according to claim 5, characterized in that: The second electronic switch tube and the third electronic switch tube are both MOS tubes.

7. The charging current limiting circuit for parallel connection of battery packs according to claim 3, characterized in that: The PWM pulse width modulation unit (42) comprises a TL494 chip, a second pin of the TL494 chip is connected to a second resistor and a third resistor, a fourteenth pin of the TL494 chip is used to output a voltage and passes through the second resistor and the third resistor respectively, so that the second pin of the TL494 chip obtains a reference voltage.

8. The charging current limiting circuit for parallel connection of battery packs according to claim 7, characterized in that: The BUCK unit (43) comprises an input signal switch circuit, a driver chip, a first output signal switch circuit, a second output signal switch circuit and a detection resistor; The controlled end of the input signal switch circuit is connected to the ninth pin of the TL494 chip, the first end of the input signal switch circuit is connected to the input end of the driver chip, the first output end of the driver chip is connected to the controlled end of the first output signal switch circuit, the second output end of the driver chip is connected to the controlled end of the second output signal switch circuit, and the first end of the detection resistor is connected to the first end of the first output signal switch circuit and the first pin of the PWM pulse width modulation unit.

9. The charging current limiting circuit for parallel connection of battery packs according to claim 8, characterized in that: The first output signal switching circuit includes a fourth electronic switch tube, a controlled end of the fourth electronic switch tube is connected to the first output end of the driver chip, the second output signal switching circuit includes a fifth electronic switch tube, a controlled end of the fifth electronic switch tube is connected to the second output end of the driver chip, and the fourth electronic switch tube and the fifth electronic switch tube are connected in parallel.

10. The charging current limiting circuit for parallel connection of battery packs according to claim 9, characterized in that: The model of the driver chip is IR4427.

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