A finished lithium battery protection status leakage current measurement system

Abstract

The present invention provides a leakage current measurement system for the protection state of finished lithium batteries in the technical field of lithium battery testing equipment, which includes a control module, a DAC module, a constant current source for charge and discharge and a short-circuit control module, a charge and discharge path selection module, a current acquisition module, an ADC module, and a host computer; the control module is respectively connected to the DAC module, the constant current source for charge and discharge and the short-circuit control module, the charge and discharge path selection module, the current acquisition module, the ADC module, and the host computer; the input end of the constant current source for charge and discharge and the short-circuit control module is connected to the output end of the DAC module, and the output end is connected to the input end of the charge and discharge path selection module; the input end of the current acquisition module is connected to the output end of the charge and discharge path selection module, and the output end is connected to the input end of the ADC module and the input end of the constant current source for charge and discharge and the short-circuit control module; the output end of the DAC module is connected to the input end of the ADC module. The advantages of the present invention are as follows: it can accurately measure the leakage current in the protection state of finished lithium batteries.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery testing equipment, and particularly to a leakage current measurement system for the protection state of finished lithium batteries. Background Art

[0002] A finished lithium battery is a product obtained by encapsulating a battery cell and a battery cell protection board. After the production of the finished lithium battery, a series of tests need to be carried out, and overcurrent protection during charging, overcurrent protection during discharging, and short-circuit protection are among the test items.

[0003] Traditionally, only the current values when the finished lithium battery triggers overcurrent protection during charging, overcurrent protection during discharging, and short-circuit protection are tested, and the corresponding leakage current values are not tested. It is only a simple judgment whether the leakage current values when triggering overcurrent protection during charging, overcurrent protection during discharging, and short-circuit protection exceed the set current threshold. However, the leakage current value is directly related to the service life of the finished lithium battery, and an excessive leakage current value may even cause the risk of damage to the finished lithium battery. In the context of more refined classification of the quality of finished lithium batteries, it is necessary to accurately measure the corresponding leakage current magnitude when the finished lithium battery triggers overcurrent protection during charging, overcurrent protection during discharging, and short-circuit protection.

[0004] Therefore, how to provide a leakage current measurement system for the protection state of finished lithium batteries to accurately measure the leakage current in the protection state of finished lithium batteries has become an urgent technical problem to be solved. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a leakage current measurement system for the protection state of finished lithium batteries to accurately measure the leakage current in the protection state of finished lithium batteries.

[0006] The present invention is implemented as follows: A leakage current measurement system for the protection state of finished lithium batteries includes a control module, a DAC module, a constant current source for charge and discharge and a short-circuit control module, a charge and discharge path selection module, a current acquisition module, an ADC module, and a host computer;

[0007] The control module is respectively connected to the DAC module, the constant current source for charge and discharge and the short-circuit control module, the charge and discharge path selection module, the current acquisition module, the ADC module, and the host computer; the input end of the constant current source for charge and discharge and the short-circuit control module is connected to the output end of the DAC module, and the output end is connected to the input end of the charge and discharge path selection module; the input end of the current acquisition module is connected to the output end of the charge and discharge path selection module, and the output end is connected to the input end of the ADC module and the input end of the constant current source for charge and discharge and the short-circuit control module; the output end of the DAC module is connected to the input end of the ADC module.

[0008] Further, the control module includes an MCU, an Ethernet interface, and a peripheral circuit;

[0009] The MCU is respectively connected to the Ethernet interface, the peripheral circuit, the DAC module, the charge and discharge constant current source and short - circuit control module, the charge and discharge path selection module, the current acquisition module, and the ADC module; the Ethernet interface is connected to the host computer.

[0010] Further, the DAC module includes a DAC chip N1, a resistor TR1, a capacitor TC6, a capacitor TC7, and a capacitor TC8;

[0011] Pin 3 and pin 7 of the DAC chip N1 are connected to the charge and discharge constant current source and short - circuit control module, pins 12, 13, and 14 are respectively connected to pins 83, 84, and 82 of the MCU, pin 15 is connected to the resistor TR1 and the capacitor TC8, and pins 9, 10, and 16 are grounded; after the capacitor TC6 and the capacitor TC7 are connected in parallel, one end is connected to pin 1 of the DAC chip N1 and the ADC module, and the other end is grounded.

[0012] Further, the charge and discharge constant current source and short - circuit control module includes an operational amplifier U2A, an operational amplifier U2B, an operational amplifier U3, an operational amplifier U4A, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a resistor R17, a resistor R18, a resistor R19, a resistor R20, a resistor R21, a resistor R22, a resistor R23, a resistor R24, a resistor R25, a resistor R27, a resistor R44, a resistor R62, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, a MOS transistor Q1, a MOS transistor Q2, a MOS transistor Q3, a MOS transistor Q4, a MOS transistor Q5, a MOS transistor Q6, a MOS transistor Q8, a diode D1, an optocoupler U1, and a gate driver chip U10;

[0013] Pins 1 and 4 of the operational amplifier U3 are connected to the current acquisition module, pin 6 is connected to the resistor R15 and grounded, and pin 7 is connected to the resistor R6, the resistor R13, and the capacitor C2;

[0014] One end of the resistor R2 is connected to the DAC module, and the other end is connected to the capacitor C1 and the pin 3 of the operational amplifier U2A; the pin 2 of the operational amplifier U2A is connected to the resistor R6, the capacitor C2 and the resistor R11, the pin 1 is connected to the resistor R4, the pin 4 is connected to the pin 6 of the gate driver chip U10, and the pin 8 is connected to the pins 1 and 8 of the gate driver chip U10; the pins 2 and 4 of the gate driver chip U10 are both connected to the pin 63 of the MCU; one end of the capacitor C3 is connected to the resistor R11, and the other end is connected to the resistor R4, the drain of the MOS transistor Q3, the output end of the diode D1 and the pin 1 of the optocoupler U1; one end of the resistor R8 is connected to the gate of the MOS transistor Q3 and the pin 92 of the MCU, and the other end is connected to the source of the MOS transistor Q3 and grounded; the pin 2 of the optocoupler U1 is connected to the input end of the diode D1 and grounded, and the pin 3 is connected to the resistor R1 and the resistor R3; the gate of the MOS transistor Q1 is connected to the resistor R1 and the resistor R5, the source is connected to the resistor R5 and the resistor R9, and the drain is connected to the drain of the MOS transistor Q2; the gate of the MOS transistor Q2 is connected to the resistor R3 and the resistor R7, the source is connected to the resistor R7 and the resistor R10; the resistor R9 is connected to the resistor R10 and the charge and discharge path selection module;

[0015] The pin 6 of the operational amplifier U2B is connected to the resistor R12 and the resistor R13, and the pin 7 is connected to the resistor R12, the resistor R44 and the capacitor C5; the pin 1 of the operational amplifier U4A is connected to the resistor R16, the pin 2 is connected to the resistor R44, the resistor R14 and the capacitor C5, the pin 3 is connected to the resistor R20 and the capacitor C6, the pin 4 is connected to the pin 6 of the gate driver chip U10, and the pin 8 is connected to the pins 1 and 8 of the gate driver chip U10; the resistor R14 is connected to the capacitor C4; the resistor R20 is connected to the DAC module;

[0016] The gate of the MOS transistor Q8 is connected to the resistor R27 and the pin 91 of the MCU, the source is connected to the resistor R27 and grounded, and the drain is connected to the resistor R16, the resistor R17, the resistor R18 and the capacitor C4; the gate of the MOS transistor Q4 is connected to the resistor R17 and the resistor R21, the source is connected to the resistor R21 and the resistor R62, and the drain is connected to the drain of the MOS transistor Q5, the drain of the MOS transistor Q6 and the charge and discharge path selection module; the gate of the MOS transistor Q5 is connected to the resistor R18 and the resistor R22, the source is connected to the resistor R22 and the resistor R24; the gate of the MOS transistor Q6 is connected to the resistor R19 and the resistor R23, the source is connected to the resistor R23 and the resistor R25; the resistor R62 is connected to the resistor R24 and the resistor R25; the resistor R19 is connected to the pins 5 and 7 of the gate driver chip U10.

[0017] Further, the charge and discharge path selection module includes a relay K1, a relay K2, a relay K3, a diode D2, a diode D3, a diode D4, a MOS transistor Q7, a MOS transistor Q9, a MOS transistor Q15, a resistor R26, a resistor R31, and a resistor R63;

[0018] Pin 1 of the relay K1 is connected to the input end of the diode D2 and the drain of the MOS transistor Q15. Pins 2 and 3 are connected to the charge and discharge constant current source and the short - circuit control module. Pin 4 is connected to pin 3 of the relay K2. Pin 5 is connected to the output end of the diode D2. The gate of the MOS transistor Q15 is connected to the resistor R63 and pin 78 of the MCU. The source is connected to the resistor R63 and grounded;

[0019] Pin 1 of the relay K2 is connected to the input end of the diode D3 and the drain of the MOS transistor Q7. Pin 4 is connected to the current acquisition module. Pin 5 is connected to the output end of the diode D3. The gate of the MOS transistor Q7 is connected to the resistor R26 and pin 77 of the MCU. The source is connected to the resistor R26 and grounded;

[0020] Pin 1 of the relay K3 is connected to the input end of the diode D4 and the drain of the MOS transistor Q9. Pins 3 and 4 are connected to the current acquisition module. Pin 5 is connected to the output end of the diode D4. The gate of the MOS transistor Q9 is connected to the resistor R31 and pin 76 of the MCU. The source is connected to the resistor R31 and grounded.

[0021] Further, the current acquisition module includes a resistor R33, a resistor R34, a resistor R35, a resistor R37, a resistor R38, a resistor R39, a resistor R40, a resistor R42, a resistor R43, a resistor R45, a resistor R46, a resistor R47, a resistor R48, a resistor R49, a resistor R50, a resistor R51, a resistor R52, a resistor R53, a resistor R54, a resistor R55, a resistor R56, a resistor R57, a resistor R58, a resistor R59, a resistor R64, a resistor R66, a resistor R67, a resistor R68, a resistor R69, a resistor R70, a resistor R71, a resistor R72, an operational amplifier U5A, an operational amplifier U5B, an operational amplifier U6, an operational amplifier U8A, an operational amplifier U8B, a capacitor C26, a capacitor C27, a capacitor C29, a capacitor C31, a capacitor C32, a capacitor C34, a capacitor C35, a capacitor C36, a capacitor C38, a capacitor C39, a relay K4, a relay K5, a relay K7, a relay K8, a diode D5, a diode D6, a diode D7, a diode D8, a diode D9, a MOS transistor Q10, a MOS transistor Q11, a MOS transistor Q12, a MOS transistor Q13, a MOS transistor Q14, an opto-relay K6, a sampling resistor R28, a sampling resistor R60, a sampling resistor R61, and a multiplexer U9;

[0022] Pin 5 of the operational amplifier U5B is connected to the resistor R33 and the capacitor C27, and pins 6 and 7 are connected to the resistor R35, the capacitor C26, and the ADC module; One end of the resistor R34 is connected to the resistor R33 and the capacitor C26, and the other end is connected to the resistor R40, pin 7 of the operational amplifier U6, and the charge and discharge constant current source and short - circuit control module;

[0023] Pin 1 of the operational amplifier U6 is connected to the resistor R37, the capacitor C29, and the capacitor C31, pin 2 is connected to pin 8 of the multiplexer U9, pin 3 is connected to the resistors R51, R52, R53, R54, R55, R56, R57, and R58, pin 4 is connected to the resistor R42, the capacitor C31, and the capacitor C35, and pin 6 is connected to the resistors R35, R49, and pin 7 of the operational amplifier U8B; Pins 4, 5, 6, 7, 12, 11, 10, 9 of the multiplexer U9 are respectively connected to the resistors R51, R52, R53, R54, R55, R56, R57, and R58;

[0024] Pin 5 of the operational amplifier U8B is connected to resistor R39 and capacitor C32, and pin 6 is connected to resistor R40 and resistor R45; pins 1 and 2 of the operational amplifier U8A are connected to resistor R39, and pin 3 is connected to resistor R38, resistor R43 and capacitor C34; capacitor C34 is connected to resistor R43 and grounded;

[0025] Pins 1 and 2 of the operational amplifier U5A are connected to resistor R50, capacitor C36 and the ADC module, and pin 3 is connected to resistor R48 and capacitor C38; resistor R48 is connected to resistor R49 and capacitor C36;

[0026] Pin 1 of the relay K4 is connected to the output terminal of the diode D5, pin 2 is connected to resistor R42, pin 3 is connected to resistor R37, pin 4 is connected to pin 2 of the relay K8, pin 5 is connected to pin 3 of the sampling resistor R28, pin 6 is connected to pin 2 of the sampling resistor R60 and pin 2 of the sampling resistor R61, pin 7 is connected to pin 2 of the sampling resistor R28, and pin 8 is connected to the input terminal of the diode D5 and the drain of the MOS transistor Q10; the source of the MOS transistor Q10 is connected to resistor R47 and grounded, and the gate is connected to resistor R46 and capacitor R47; resistor R46 is connected to pin 75 of the MCU; pin 1 of the sampling resistor R28 is connected to the charge and discharge path selection module, and pin 4 is connected to resistor R30;

[0027] Pin 1 of the opto-relay K6 is connected to resistor R59 and the output terminal of the diode D6, pin 2 is connected to the input terminal of the diode D6 and the drain of the MOS transistor Q11, pin 3 is connected to pin 4 of the relay K7 and the charge and discharge path selection module, and pin 4 is connected to pin 6 of the relay K7 and the charge and discharge path selection module; one end of the resistor R64 is connected to resistor R66 and the gate of the MOS transistor Q11, and the other end is connected to pin 73 of the MCU; resistor R66 is connected to the source of the MOS transistor Q11 and grounded;

[0028] Pin 1 of the relay K7 is connected to the output terminal of the diode D7, pin 2 is connected to pin 2 of the relay K5, pin 3 is connected to pin 3 of the relay K5, and pin 8 is connected to the input terminal of the diode D7 and the drain of the MOS transistor Q13; one end of the resistor R67 is connected to resistor R69 and the gate of the MOS transistor Q13, and the other end is connected to pin 72 of the MCU; resistor R69 is connected to the source of the MOS transistor Q13 and grounded;

[0029] Pin 1 of the relay K5 is connected to the output terminal of the diode D8 and the capacitor C39, pin 4 is connected to pin 1 of the sampling resistor R61, pin 5 is connected to pin 1 of the sampling resistor R60, pin 6 is connected to pin 4 of the sampling resistor R61, pin 7 is connected to pin 4 of the sampling resistor R60, and pin 8 is connected to the input terminal of the diode D8 and the drain of the MOS transistor Q12; One end of the resistor R68 is connected to the resistor R71 and the gate of the MOS transistor Q12, and the other end is connected to pin 74 of the MCU; The resistor R71 is connected to the source of the MOS transistor Q12 and grounded;

[0030] Pin 1 of the relay K8 is connected to the output terminal of the diode D9, pin 2 is connected to pin 4 of the relay K4, pin 3 is connected to pin 6 of the relay K4, pin 4 is connected to pin 2 of the sampling resistor R60, pin 5 is connected to pin 2 of the sampling resistor R61, pin 6 is connected to pin 3 of the sampling resistor R60, pin 7 is connected to pin 3 of the sampling resistor R61, and pin 8 is connected to the input terminal of the diode D9 and the drain of the MOS transistor Q14; One end of the resistor R70 is connected to the resistor R72 and the gate of the MOS transistor Q14, and the other end is connected to pin 71 of the MCU; The resistor R72 is connected to the source of the MOS transistor Q14 and grounded.

[0031] Further, the ADC module includes an ADC chip U7, a resistor R36, a resistor R41, a capacitor C28, a capacitor C30, and a capacitor C33;

[0032] Pin 1 of the ADC chip U7 is connected to the resistor R36, the capacitor C28, and the capacitor C30, pin 2 is connected to the resistor R41, the capacitor C30, and the capacitor C33, pins 5 and 6 are connected to pins 85 and 86 of the MMCU, pin 7 is grounded, and pin 8 is connected to the DAC module.

[0033] The advantages of the present invention are as follows:

[0034] By setting up the charge and discharge constant current source and the short - circuit control module, the functions of charge and discharge and short - circuit are provided, enabling the finished lithium battery to enter the charging over - current protection state, discharging over - current protection state or short - circuit protection state; by setting that the MOS transistors Q1, Q2, Q3, Q4, Q5, Q6 and Q8 of the charge and discharge constant current source and the short - circuit control module are all NPN - type MOS transistors, that is, the short - circuit test of the finished lithium battery is carried out through the NPN - type MOS transistors (linear adjustment and short - circuit switch through MOS transistors), avoiding the problems of relay adhesion and reduced service life existing in the electrified switching of mechanical relays. After the finished lithium battery enters the corresponding protection state, the resistance value of the sampling resistor can be increased without triggering the recovery of the finished lithium battery from the protection state; by setting up the combination of the relay and the operational amplifier, the measurement current range can be flexibly switched, improving the signal - to - noise ratio of the current signal acquisition; using the PID regulation method for the charge and discharge constant current loop makes the measured charge and discharge current more stable. Using the relay alone to switch the charge and discharge loop can accurately measure the leakage current value of the finished lithium battery in different protection states, and finally achieve the accurate measurement of the leakage current of the finished lithium battery in the protection state. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will be further described below with reference to the accompanying drawings in conjunction with embodiments.

[0036] Figure 1 It is a circuit principle block diagram of a leakage current measurement system for the protection state of a finished lithium battery according to the present invention.

[0037] Figure 2 It is a circuit diagram of the MCU of the present invention.

[0038] Figure 3 It is a circuit diagram of the Ethernet interface of the present invention.

[0039] Figure 4 It is a circuit diagram of the peripheral circuit of the present invention.

[0040] Figure 5 It is a circuit diagram of the DAC module of the present invention.

[0041] Figure 6 It is a circuit diagram of the charge and discharge constant current source and the short - circuit control module of the present invention.

[0042] Figure 7 It is a circuit diagram of the charge and discharge path selection module of the present invention.

[0043] Figure 8 It is a circuit diagram of the current acquisition module of the present invention.

[0044] Figure 9 It is a circuit diagram of the ADC module of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0045] Please refer to Figures 1 to 9 As shown, a preferred embodiment of a leakage current measurement system for the protection state of a finished lithium battery according to the present invention includes a control module, a DAC module, a constant current source for charge and discharge and a short - circuit control module, a charge - discharge path selection module, a current acquisition module, an ADC module, and a host computer;

[0046] The control module conducts data transmission and interaction with the host computer through an Ethernet interface, and the user issues commands to the MCU through the host computer; the DAC module and the MCU accurately output a voltage quantity to the constant current source for charge and discharge and the short - circuit control module, and provide the reference voltage internally provided by the DAC chip N1 to the ADC module for use as a reference voltage; the constant current source for charge and discharge and the short - circuit control module is used to convert the voltage quantity transmitted by the DAC module into a current quantity through proportional, integral, and derivative control (abbreviated as PID control adjustment circuit), conduct constant current source control for charge and discharge, and implement the short - circuit test function of the finished lithium battery through the switch of the NPN - type MOS tube; the charge - discharge path selection module is used to switch the current working state to a charging state, a discharging state, or a disconnection mode; the current acquisition module is used to collect and process current signals, and transmit the collected current signals to the constant current source for charge and discharge and the short - circuit control module during the over - current protection of the charge and discharge of the finished lithium battery for PID control adjustment, so as to form a current value matching the set value in the electrical circuit, filter the collected value and then transmit it to the ADC module for analog - to - digital conversion. When the finished lithium battery enters the protection state, through the control of the control module, the current acquisition circuit is switched to collect the leakage current in the protection state, collect the leakage current in the corresponding protection state, filter the corresponding collected value and then transmit it to the ADC module for analog - to - digital conversion; the ADC module is used to convert the current signal from analog to digital and then transmit it to the MCU;

[0047] The control module is respectively connected to the DAC module, the constant current source for charge and discharge and the short - circuit control module, the charge - discharge path selection module, the current acquisition module, the ADC module, and the host computer; the input end of the constant current source for charge and discharge and the short - circuit control module is connected to the output end of the DAC module, and the output end is connected to the input end of the charge - discharge path selection module; the input end of the current acquisition module is connected to the output end of the charge - discharge path selection module, and the output end is connected to the input end of the ADC module and the input end of the constant current source for charge and discharge and the short - circuit control module; the output end of the DAC module is connected to the input end of the ADC module.

[0048] The control module includes an MCU, an Ethernet interface, and a peripheral circuit; the MCU is used to control the level output of the DAC module, enable control over the charge and discharge constant current source and short - circuit control module, control the charge and discharge path selection module to select the current working state as the charging state, discharging state, or disconnect mode, control the switching of the current acquisition function of the current acquisition module and the signal amplification gain of the acquisition circuit, process the digital signal transmitted from the ADC module and transmit it to the upper computer, and conduct information interaction with the upper computer. The preferred model is the ARM microprocessor TM4C1294;

[0049] The MCU is respectively connected to the Ethernet interface, the peripheral circuit, the DAC module, the charge and discharge constant current source and short - circuit control module, the charge and discharge path selection module, the current acquisition module, and the ADC module; the Ethernet interface is connected to the upper computer.

[0050] The DAC module includes a DAC chip N1, a resistor TR1, a capacitor TC6, a capacitor TC7, and a capacitor TC8; the preferred model of the DAC chip N1 is AD5689;

[0051] Pin 3 and pin 7 of the DAC chip N1 are connected to the charge and discharge constant current source and short - circuit control module, pins 12, 13, and 14 are respectively connected to pins 83, 84, and 82 of the MCU, pin 15 is connected to the resistor TR1 and the capacitor TC8, and pins 9, 10, and 16 are grounded; after the capacitor TC6 and the capacitor TC7 are connected in parallel, one end is connected to pin 1 of the DAC chip N1 and the ADC module, and the other end is grounded.

[0052] The constant current source for charge and discharge and the short - circuit control module includes an operational amplifier U2A, an operational amplifier U2B, an operational amplifier U3, an operational amplifier U4A, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a resistor R17, a resistor R18, a resistor R19, a resistor R20, a resistor R21, a resistor R22, a resistor R23, a resistor R24, a resistor R25, a resistor R27, a resistor R44, a resistor R62, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, a MOS transistor Q1, a MOS transistor Q2, a MOS transistor Q3, a MOS transistor Q4, a MOS transistor Q5, a MOS transistor Q6, a MOS transistor Q8, a diode D1, an optocoupler U1, and a gate driver chip U10; the gate driver chip U10 performs switching actions on the MOS transistors, greatly improving the short - circuit response speed, and the model is preferably UCC27424; by using the method of multiple MOS in parallel, the power that the MOS transistors in the charge and discharge loop can withstand is increased; the model of the optocoupler U1 is preferably SFH6156;

[0053] Pin 1 and pin 4 of the operational amplifier U3 are connected to the current acquisition module, pin 6 is connected to the resistor R15 and grounded, and pin 7 is connected to the resistor R6, the resistor R13, and the capacitor C2;

[0054] One end of the resistor R2 is connected to the DAC module, and the other end is connected to the capacitor C1 and pin 3 of the operational amplifier U2A; pin 2 of the operational amplifier U2A is connected to the resistor R6, the capacitor C2, and the resistor R11, pin 1 is connected to the resistor R4, pin 4 is connected to pin 6 of the gate driver chip U10, and pin 8 is connected to pin 1 and pin 8 of the gate driver chip U10; pins 2 and 4 of the gate driver chip U10 are both connected to pin 63 of the MCU; one end of the capacitor C3 is connected to the resistor R11, and the other end is connected to the resistor R4, the drain of the MOS transistor Q3, the output end of the diode D1, and pin 1 of the optocoupler U1; one end of the resistor R8 is connected to the gate of the MOS transistor Q3 and pin 92 of the MCU, and the other end is connected to the source of the MOS transistor Q3 and grounded; pin 2 of the optocoupler U1 is connected to the input end of the diode D1 and grounded, and pin 3 is connected to the resistor R1 and the resistor R3; the gate of the MOS transistor Q1 is connected to the resistor R1 and the resistor R5, the source is connected to the resistor R5 and the resistor R9, and the drain is connected to the drain of the MOS transistor Q2; the gate of the MOS transistor Q2 is connected to the resistor R3 and the resistor R7, the source is connected to the resistor R7 and the resistor R10; the resistor R9, the resistor R10, and the charge and discharge path selection module are connected;

[0055] Pin 6 of the operational amplifier U2B is connected to resistor R12 and resistor R13, and pin 7 is connected to resistor R12, resistor R44, and capacitor C5; pin 1 of the operational amplifier U4A is connected to resistor R16, pin 2 is connected to resistor R44, resistor R14, and capacitor C5, pin 3 is connected to resistor R20 and capacitor C6, pin 4 is connected to pin 6 of the gate driver chip U10, and pin 8 is connected to pins 1 and 8 of the gate driver chip U10; resistor R14 is connected to capacitor C4; resistor R20 is connected to the DAC module;

[0056] The gate of the MOS transistor Q8 is connected to resistor R27 and pin 91 of the MCU, the source is connected to resistor R27 and grounded, and the drain is connected to resistor R16, resistor R17, resistor R18, and capacitor C4; the gate of the MOS transistor Q4 is connected to resistor R17 and resistor R21, the source is connected to resistor R21 and resistor R62, and the drain is connected to the drain of the MOS transistor Q5, the drain of the MOS transistor Q6, and the charge and discharge path selection module; the gate of the MOS transistor Q5 is connected to resistor R18 and resistor R22, the source is connected to resistor R22 and resistor R24; the gate of the MOS transistor Q6 is connected to resistor R19 and resistor R23, the source is connected to resistor R23 and resistor R25; resistor R62 is connected to resistor R24 and resistor R25; resistor R19 is connected to pins 5 and 7 of the gate driver chip U10.

[0057] The charge and discharge path selection module includes a relay K1, a relay K2, a relay K3, a diode D2, a diode D3, a diode D4, a MOS transistor Q7, a MOS transistor Q9, a MOS transistor Q15, a resistor R26, a resistor R31, and a resistor R63;

[0058] Pin 1 of the relay K1 is connected to the input end of the diode D2 and the drain of the MOS transistor Q15, pins 2 and 3 are connected to the charge and discharge constant current source and short - circuit control module, pin 4 is connected to pin 3 of the relay K2, and pin 5 is connected to the output end of the diode D2; the gate of the MOS transistor Q15 is connected to resistor R63 and pin 78 of the MCU, and the source is connected to resistor R63 and grounded;

[0059] Pin 1 of the relay K2 is connected to the input end of the diode D3 and the drain of the MOS transistor Q7, pin 4 is connected to the current acquisition module, and pin 5 is connected to the output end of the diode D3; the gate of the MOS transistor Q7 is connected to resistor R26 and pin 77 of the MCU, and the source is connected to resistor R26 and grounded;

[0060] Pin 1 of the relay K3 is connected to the input end of the diode D4 and the drain of the MOS transistor Q9. Pins 3 and 4 are connected to the current acquisition module. Pin 5 is connected to the output end of the diode D4. The gate of the MOS transistor Q9 is connected to the resistor R31 and pin 76 of the MCU, and the source is connected to the resistor R31 and grounded.

[0061] The current acquisition module includes a resistor R33, a resistor R34, a resistor R35, a resistor R37, a resistor R38, a resistor R39, a resistor R40, a resistor R42, a resistor R43, a resistor R45, a resistor R46, a resistor R47, a resistor R48, a resistor R49, a resistor R50, a resistor R51, a resistor R52, a resistor R53, a resistor R54, a resistor R55, a resistor R56, a resistor R57, a resistor R58, a resistor R59, a resistor R64, a resistor R66, a resistor R67, a resistor R68, a resistor R69, a resistor R70, a resistor R71, a resistor R72, an operational amplifier U5A, an operational amplifier U5B, an operational amplifier U6, an operational amplifier U8A, an operational amplifier U8B, a capacitor C26, a capacitor C27, a capacitor C29, a capacitor C31, a capacitor C32, a capacitor C34, a capacitor C35, a capacitor C36, a capacitor C38, a capacitor C39, a relay K4, a relay K5, a relay K7, a relay K8, a diode D5, a diode D6, a diode D7, a diode D8, a diode D9, a MOS transistor Q10, a MOS transistor Q11, a MOS transistor Q12, a MOS transistor Q13, a MOS transistor Q14, an opto-relay K6, a sampling resistor R28, a sampling resistor R60, a sampling resistor R61, and a multiplexer switch U9. The models of the relay K4, relay K5, relay K7, and relay K8 are preferably MAX308. The opto-relay K6 is used to eliminate the influence caused by the jitter of the relay K7. The MOS transistors Q1 to Q15 are all NPN-type MOS transistors. The models of the operational amplifiers U3 and U6 are preferably AD8421. The models of the operational amplifiers U2A, U2B, U4A, U5A, U5B, U8A, and U8B are all OPA2188. The model of the opto-relay K6 is preferably AQY212S. The relays K1, K2, and K3 use mechanical relays with relatively large power, and the model is preferably G2RL-1-E-CN-DC24. The relays K4, K5, K7, and K8 use mechanical relays with relatively small power, and the model is preferably HFD4 / 12-SR.

[0062] Pin 5 of the operational amplifier U5B is connected to resistor R33 and capacitor C27, and pins 6 and 7 are connected to resistor R35, capacitor C26, and the ADC module; one end of resistor R34 is connected to resistor R33 and capacitor C26, and the other end is connected to resistor R40, pin 7 of operational amplifier U6, and the charge and discharge constant current source and short - circuit control module;

[0063] Pin 1 of the operational amplifier U6 is connected to resistor R37, capacitor C29, and capacitor C31, pin 2 is connected to pin 8 of the multiplexer switch U9, pin 3 is connected to resistor R51, resistor R52, resistor R53, resistor R54, resistor R55, resistor R56, resistor R57, and resistor R58, pin 4 is connected to resistor R42, capacitor C31, and capacitor C35, pin 6 is connected to resistor R35, resistor R49, and pin 7 of operational amplifier U8B; pins 4, 5, 6, 7, 12, 11, 10, 9 of the multiplexer switch U9 are respectively connected to resistor R51, resistor R52, resistor R53, resistor R54, resistor R55, resistor R56, resistor R57, and resistor R58;

[0064] Pin 5 of the operational amplifier U8B is connected to resistor R39 and capacitor C32, and pin 6 is connected to resistor R40 and resistor R45; pins 1 and 2 of the operational amplifier U8A are connected to resistor R39, and pin 3 is connected to resistor R38, resistor R43, and capacitor C34; capacitor C34 is connected to resistor R43 and grounded;

[0065] Pins 1 and 2 of the operational amplifier U5A are connected to resistor R50, capacitor C36, and the ADC module, and pin 3 is connected to resistor R48 and capacitor C38; resistor R48 is connected to resistor R49 and capacitor C36;

[0066] Pin 1 of the relay K4 is connected to the output end of diode D5, pin 2 is connected to resistor R42, pin 3 is connected to resistor R37, pin 4 is connected to pin 2 of relay K8, pin 5 is connected to pin 3 of the sampling resistor R28, pin 6 is connected to pin 2 of the sampling resistor R60 and pin 2 of the sampling resistor R61, pin 7 is connected to pin 2 of the sampling resistor R28, pin 8 is connected to the input end of diode D5 and the drain of the MOS transistor Q10; the source of the MOS transistor Q10 is connected to resistor R47 and grounded, and the gate is connected to resistor R46 and capacitor R47; resistor R46 is connected to pin 75 of the MCU; pin 1 of the sampling resistor R28 is connected to the charge and discharge path selection module, and pin 4 is connected to resistor R30;

[0067] Pin 1 of the opto-relay K6 is connected to the output terminal of the resistor R59 and the diode D6, pin 2 is connected to the input terminal of the diode D6 and the drain of the MOS transistor Q11, pin 3 is connected to pin 4 of the relay K7 and the charge and discharge path selection module, and pin 4 is connected to pin 6 of the relay K7 and the charge and discharge path selection module; One end of the resistor R64 is connected to the resistor R66 and the gate of the MOS transistor Q11, and the other end is connected to pin 73 of the MCU; The resistor R66 is connected to the source of the MOS transistor Q11 and grounded;

[0068] Pin 1 of the relay K7 is connected to the output terminal of the diode D7, pin 2 is connected to pin 2 of the relay K5, pin 3 is connected to pin 3 of the relay K5, and pin 8 is connected to the input terminal of the diode D7 and the drain of the MOS transistor Q13; One end of the resistor R67 is connected to the resistor R69 and the gate of the MOS transistor Q13, and the other end is connected to pin 72 of the MCU; The resistor R69 is connected to the source of the MOS transistor Q13 and grounded;

[0069] Pin 1 of the relay K5 is connected to the output terminal of the diode D8 and the capacitor C39, pin 4 is connected to pin 1 of the sampling resistor R61, pin 5 is connected to pin 1 of the sampling resistor R60, pin 6 is connected to pin 4 of the sampling resistor R61, pin 7 is connected to pin 4 of the sampling resistor R60, and pin 8 is connected to the input terminal of the diode D8 and the drain of the MOS transistor Q12; One end of the resistor R68 is connected to the resistor R71 and the gate of the MOS transistor Q12, and the other end is connected to pin 74 of the MCU; The resistor R71 is connected to the source of the MOS transistor Q12 and grounded;

[0070] Pin 1 of the relay K8 is connected to the output terminal of the diode D9, pin 2 is connected to pin 4 of the relay K4, pin 3 is connected to pin 6 of the relay K4, pin 4 is connected to pin 2 of the sampling resistor R60, pin 5 is connected to pin 2 of the sampling resistor R61, pin 6 is connected to pin 3 of the sampling resistor R60, pin 7 is connected to pin 3 of the sampling resistor R61, and pin 8 is connected to the input terminal of the diode D9 and the drain of the MOS transistor Q14; One end of the resistor R70 is connected to the resistor R72 and the gate of the MOS transistor Q14, and the other end is connected to pin 71 of the MCU; The resistor R72 is connected to the source of the MOS transistor Q14 and grounded.

[0071] The ADC module includes an ADC chip U7, a resistor R36, a resistor R41, a capacitor C28, a capacitor C30, and a capacitor C33; The model of the ADC chip U7 is preferably ADS1252;

[0072] Pin 1 of the ADC chip U7 is connected to resistor R36, capacitor C28, and capacitor C30; pin 2 is connected to resistor R41, capacitor C30, and capacitor C33; pins 5 and 6 are connected to pins 85 and 86 of the MMCU; pin 7 is grounded; and pin 8 is connected to the DAC module.

[0073] Working principle of the present invention:

[0074] The host computer sends a test instruction carrying test parameters to the MCU; the test parameters include the current value of overcurrent protection during charging, the current value of overcurrent protection during discharging, and the protection trigger time when the overcurrent protection during charging, overcurrent protection during discharging, and short - circuit protection of the finished lithium battery reach the protection value.

[0075] The following separately elaborates on the preliminary actions of the three protection states, and the leakage current sampling action is elaborated uniformly. During the test, the positive and negative electrodes of the finished lithium battery are respectively connected to PACK + and PACK -.

[0076] Constant - current charging action before leakage current test in the over - current protection state during charging:

[0077] Based on the test instruction sent by the host computer, the MCU sets pins 76, 77, 78, and 91 of the MCU to high level and pin 92 to low level, thereby controlling relays K1, K2, and K3 in the charge - discharge path selection module to be in the normally - open contact state, forming a charging test circuit; controlling MOS transistor Q8 to be in the conducting state, closing the constant - current discharging circuit, and controlling MOS transistor Q3 to be in the cut - off state, opening the constant - current charging circuit. Then, the MCU sets the DAC module according to the charging current value information carried in the test instruction, making the DAC module output a corresponding voltage value. Through the cooperation of the charge - discharge constant - current source and the short - circuit control module and the current acquisition module, after obtaining the corresponding signal through operational amplifier U3, the voltage value set by the DAC module through the network number CHG_ISET and the PID adjustment module composed of operational amplifier U2A linearly adjust optocoupler U1. The output side of optocoupler U1 linearly adjusts the conduction degree of MOS transistors Q1 and Q2 through independent power supplies V1 + and V1 -, controlling the current value flowing from the front - stage power supplies P + and P - of the charger into the finished lithium battery until the current value in the circuit is constant at the set current value.

[0078] Constant - current charging action before leakage current test in the over - current protection state during discharging:

[0079] Based on the test instructions sent by the host computer, the MCU sets the pins 76, 77, and 92 of the MCU to high level, and sets the pins 78 and 91 to low level, so as to control the relays K2 and K3 in the charge and discharge path selection module to be on the normally open contacts, and the relay K1 to be on the normally closed contact, forming a discharge test circuit. Control the MOS transistor Q3 to be in the conducting state, close the constant current charging circuit, control the MOS transistor Q8 to be in the cut-off state, and turn on the constant current charge and discharge circuit. Since the flow directions of the charging and discharging currents are opposite, a signal reverse circuit composed of the resistor R12, the resistor R13, and the operational amplifier U2B is added. Then, the MCU sets the DAC module according to the discharge current value information carried in the test instructions, makes it output the corresponding voltage value. Through the cooperation of the charge and discharge constant current source and the short-circuit control module and the current acquisition module, after obtaining the corresponding signal through the operational amplifier U3, the DAC module linearly adjusts the conduction degrees of the MOS transistors Q4 and Q5 through the voltage value set by the network number DIS_ISET and the PID adjustment module composed of the operational amplifier U2B and the operational amplifier U4A, and controls the discharge current value of the finished lithium battery until the current value in the circuit is constant at the set current value.

[0080] Short-circuit action on the finished lithium battery before the leakage current test in the short-circuit protection state:

[0081] Based on the test instructions sent by the host computer, the MCU sets the pins 76 and 77 of the MCU to high level, and sets the pins 78, 91, and 92 to low level, so as to control the charge and discharge path selection relays K2 and K3 to be on the normally open contacts, and the relay K1 to be on the normally closed contact, and control the MOS transistors Q3 and Q8 to be in the cut-off state, and turn on the short-circuit test circuit. Then, the MCU controls the pin 64 to be in the high level state, and this high level signal controls the MOS transistor Q6 through the gate drive chip U10, making it quickly enter the fully saturated state from the cut-off state, and then controlling it to perform a short-circuit process on the finished lithium battery.

[0082] Description of the leakage current measurement after the finished lithium battery enters the corresponding protection state:

[0083] The current acquisition module converts the corresponding current value in the loop into a corresponding voltage value and then transmits it to the ADC module. The MCU obtains the current value collected in the loop from the ADC module in real time. When the magnitude of the charging current value of the loop reaches the charging overcurrent protection trigger value of the finished lithium battery and the protection trigger time meets the conditions, the finished lithium battery enters the charging overcurrent protection state, and then actively turns off the MOS tube inside the finished lithium battery. At this time, the current value in the loop will rapidly decrease due to the closing of the MOS of the finished lithium battery. Finally, the current value in the loop only remains the leakage current value after the finished lithium battery enters the charging overcurrent protection state. Because the current that initially causes the finished lithium battery to enter the charging overcurrent protection state is relatively large, generally at the ampere level, the selected sampling resistor R28 is a relatively small value, generally about 1 milliohm. When the finished lithium battery enters the charging overcurrent protection, the magnitude of the current value existing in the loop will decrease to microamps, and some will even decrease to the order of nanoamps. Therefore, under the condition of the original sampling resistor R28, it is very difficult to accurately collect the current value of this order of magnitude. So it is necessary to switch the sampling resistor to convert the current signal into a larger voltage signal for better signal-to-noise ratio in subsequent sampling. However, during the process of switching the sampling resistor, the finished lithium battery cannot be restored from the charging overcurrent protection state. Therefore, the finished lithium battery should not be affected by signal jitter during the process of switching the sampling resistor and the sampling point of the sampling signal. Therefore, an optocoupler relay K6 is added to the current sampling module. When the current value collected by the current acquisition module is the current value flowing through the sampling resistor R28, the MCU starts to make corresponding actions according to the current value transmitted back by the ADC module. When the detected current value is already lower than the minimum value that can be collected by the current measurement gear, the MCU module switches the multiplexer switch U9 by controlling the level states of pins 93, 94, 95, and 96. The operational amplifier U6 realizes the sampling gain of current acquisition according to the feedback resistor provided by the switching of the multiplexer switch U9, and then switches the current gear. When it is switched to the state of the minimum current value that can be collected under the condition of the sampling resistor R28, if the transmitted back current value is still lower than the minimum value of the gear, the MCU controls pin 73 to be in a high level state, making the optocoupler relay K6 in a conducting state. Because the optocoupler relay K6 does not have the mechanical jitter problem of a mechanical relay, the electrical shock generated by the mechanical jitter caused by the switching of the mechanical relay used for subsequent sampling resistor switching can be eliminated on the optocoupler relay K6, avoiding this shock from being transmitted to the measured finished lithium battery and causing it to recover from the protection state.

[0084] When the opto-coupler relay K6 is in the conducting state, the MCU controls pins 75, 72, and 71 to be at high level and pin 74 to be at low level, switches the sampling resistor of the current acquisition module from sampling resistor R28 to a sampling resistor R60 with a larger resistance value. After the switching is completed, the MCU controls pin 76 to be in a low level state, causing the relay K3 to switch to the normally closed state. When all these mechanical relays have completed the switching, the MCU controls pin 73 to be in a low level state, causing the opto-coupler relay K6 to be in the off state. Therefore, after the switching is completed, the current loop flows through the sampling resistor R60 via the network number P-_CONNECT and PACK-. The sampling point of the current acquisition module also switches to the sampling resistor R60, enabling the MCU at this time to control the loop gain of the operational amplifier U6 by switching the state of the multiplexer switch U9, thereby controlling the current sampling gear. If the loop current value at this time is still lower than the minimum current sampling value in the state of the sampling resistor R60, the sampling resistor is switched to sampling R61. The MCU controls pin 73 to be in a high level state, causing the opto-coupler relay K6 to be in the conducting state, and performs mechanical jitter elimination processing caused during the subsequent mechanical relay switching process to prevent these signals from accidentally triggering the recovery action of the finished lithium battery. The MCU controls pins 75, 72, and 74 to be at high level and pin 71 to be at low level, switches the sampling resistor of the current acquisition module from sampling resistor R60 to a sampling resistor R61 with a larger resistance value. When all these mechanical relays have completed the switching, the MCU controls pin 73 to be in a low level state, causing the opto-coupler relay K6 to be in the off state. Therefore, after the switching is completed, the current loop flows through the sampling resistor R61 via the network number P-_CONNECT and PACK-. The sampling point of the current acquisition module also switches to the sampling resistor R61, and the MCU controls the loop gain of the operational amplifier U6 by switching the state of the multiplexer switch U9, thereby controlling the current sampling gear and collecting the magnitude of the leakage current value in the loop at this moment. In the current acquisition module, through the combination of the operational amplifier U8 and the operational amplifier U6, a bias elevation process is performed on the current acquisition value, so that the leakage current values in different current directions under different test conditions can be directly obtained.

[0085] In summary, the advantages of the present invention are as follows:

[0086] By setting up a constant current source for charge and discharge and a short - circuit control module, functions of charge and discharge and short - circuit are provided, enabling the finished lithium battery to enter the over - current protection state during charging, over - current protection state during discharging or short - circuit protection state; by setting that MOS transistors Q1, Q2, Q3, Q4, Q5, Q6 and Q8 of the constant current source for charge and discharge and the short - circuit control module are all NPN - type MOS transistors, that is, a short - circuit test is performed on the finished lithium battery through NPN - type MOS transistors (linear adjustment and short - circuit switch are performed through MOS transistors), avoiding the problems of relay adhesion and reduced service life existing in the charged switching of mechanical relays. After the finished lithium battery enters the corresponding protection state, the resistance value of the sampling resistor can be increased without triggering the recovery of the finished lithium battery from the protection state; by setting up a combination of a relay and an operational amplifier, the measurement current range can be flexibly switched, improving the signal - to - noise ratio of current signal acquisition; the PID regulation method is used for the charge - discharge constant current loop to make the measured charge - discharge current more stable, and the relay is used alone for switching the charge - discharge loop, enabling accurate measurement of the leakage current value of the finished lithium battery in different protection states, and finally realizing accurate measurement of the leakage current of the finished lithium battery in the protection state.

[0087] Although the specific embodiments of the present invention have been described above, those skilled in the art of this technology should understand that the specific embodiments we described are illustrative rather than used to limit the scope of the present invention. Equivalent modifications and changes made by those skilled in the art in accordance with the spirit of the present invention should all be covered by the scope protected by the claims of the present invention.

Claims

1. A finished lithium battery protection state leakage current measurement system, characterized in that: It includes a control module, a DAC module, a charge and discharge constant current source and short - circuit control module, a charge and discharge path selection module, a current acquisition module, an ADC module, and a host computer; The control module is respectively connected to the DAC module, the charge and discharge constant current source and short - circuit control module, the charge and discharge path selection module, the current acquisition module, the ADC module, and the host computer; The input end of the charge and discharge constant current source and short - circuit control module is connected to the output end of the DAC module, and the output end is connected to the input end of the charge and discharge path selection module; The input end of the current acquisition module is connected to the output end of the charge and discharge path selection module, and the output end is connected to the input end of the ADC module and the input end of the charge and discharge constant current source and short - circuit control module; The output end of the DAC module is connected to the input end of the ADC module; The control module includes an MCU, an Ethernet interface, and a peripheral circuit; The MCU is respectively connected to the Ethernet interface, the peripheral circuit, the DAC module, the charge and discharge constant current source and short - circuit control module, the charge and discharge path selection module, the current acquisition module, and the ADC module; The Ethernet interface is connected to the host computer; The DAC module includes a DAC chip N1, a resistor TR1, a capacitor TC6, a capacitor TC7, and a capacitor TC8; Pins 3 and 7 of the DAC chip N1 are connected to the charge and discharge constant current source and short - circuit control module, pins 12, 13, and 14 are respectively connected to pins 83, 84, and 82 of the MCU, pin 15 is connected to the resistor TR1 and the capacitor TC8, and pins 9, 10, and 16 are grounded; After the capacitor TC6 and the capacitor TC7 are connected in parallel, one end is connected to pin 1 of the DAC chip N1 and the ADC module, and the other end is grounded.

2. The finished lithium battery protection state leakage current measurement system according to claim 1, characterized in that: The charge and discharge constant current source and short - circuit control module includes an operational amplifier U2A, an operational amplifier U2B, an operational amplifier U3, an operational amplifier U4A, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a resistor R17, a resistor R18, a resistor R19, a resistor R20, a resistor R21, a resistor R22, a resistor R23, a resistor R24, a resistor R25, a resistor R27, a resistor R44, a resistor R62, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, a MOS transistor Q1, a MOS transistor Q2, a MOS transistor Q3, a MOS transistor Q4, a MOS transistor Q5, a MOS transistor Q6, a MOS transistor Q8, a diode D1, an optocoupler U1, and a gate driver chip U10; Pins 1 and 4 of the operational amplifier U3 are connected to the current acquisition module, pin 6 is connected to the resistor R15 and grounded, and pin 7 is connected to the resistor R6, the resistor R13, and the capacitor C2; One end of the resistor R2 is connected to the DAC module, and the other end is connected to the capacitor C1 and pin 3 of the operational amplifier U2A; pin 2 of the operational amplifier U2A is connected to the resistor R6, the capacitor C2, and the resistor R11, pin 1 is connected to the resistor R4, pin 4 is connected to pin 6 of the gate driver chip U10, and pin 8 is connected to pins 1 and 8 of the gate driver chip U10; pins 2 and 4 of the gate driver chip U10 are both connected to pin 63 of the MCU; one end of the capacitor C3 is connected to the resistor R11, and the other end is connected to the resistor R4, the drain of the MOS transistor Q3, the output end of the diode D1, and pin 1 of the optocoupler U1; one end of the resistor R8 is connected to the gate of the MOS transistor Q3 and pin 92 of the MCU, and the other end is connected to the source of the MOS transistor Q3 and grounded; pin 2 of the optocoupler U1 is connected to the input end of the diode D1 and grounded, and pin 3 is connected to the resistor R1 and the resistor R3; the gate of the MOS transistor Q1 is connected to the resistor R1 and the resistor R5, the source is connected to the resistor R5 and the resistor R9, and the drain is connected to the drain of the MOS transistor Q2; the gate of the MOS transistor Q2 is connected to the resistor R3 and the resistor R7, the source is connected to the resistor R7 and the resistor R10; the resistor R9 is connected to the resistor R10 and the charge and discharge path selection module; Pin 6 of the operational amplifier U2B is connected to the resistor R12 and the resistor R13, and pin 7 is connected to the resistor R12, the resistor R44, and the capacitor C5; pin 1 of the operational amplifier U4A is connected to the resistor R16, pin 2 is connected to the resistor R44, the resistor R14, and the capacitor C5, pin 3 is connected to the resistor R20 and the capacitor C6, pin 4 is connected to pin 6 of the gate driver chip U10, and pin 8 is connected to pins 1 and 8 of the gate driver chip U10; the resistor R14 is connected to the capacitor C4; the resistor R20 is connected to the DAC module; The gate of the MOS transistor Q8 is connected to the resistor R27 and pin 91 of the MCU, the source is connected to the resistor R27 and grounded, and the drain is connected to the resistor R16, the resistor R17, the resistor R18, and the capacitor C4; the gate of the MOS transistor Q4 is connected to the resistor R17 and the resistor R21, the source is connected to the resistor R21 and the resistor R62, and the drain is connected to the drain of the MOS transistor Q5, the drain of the MOS transistor Q6, and the charge and discharge path selection module; the gate of the MOS transistor Q5 is connected to the resistor R18 and the resistor R22, the source is connected to the resistor R22 and the resistor R24; the gate of the MOS transistor Q6 is connected to the resistor R19 and the resistor R23, the source is connected to the resistor R23 and the resistor R25; the resistor R62 is connected to the resistor R24 and the resistor R25; the resistor R19 is connected to pins 5 and 7 of the gate driver chip U10.

3. The finished lithium battery protection state leakage current measurement system according to claim 1, characterized in that: The charge and discharge path selection module includes a relay K1, a relay K2, a relay K3, a diode D2, a diode D3, a diode D4, a MOS transistor Q7, a MOS transistor Q9, a MOS transistor Q15, a resistor R26, a resistor R31, and a resistor R63; The pin 1 of the relay K1 is connected to the input terminal of the diode D2 and the drain of the MOS transistor Q15, the pins 2 and 3 are connected to the charge and discharge constant current source and the short - circuit control module, the pin 4 is connected to the pin 3 of the relay K2, and the pin 5 is connected to the output terminal of the diode D2; the gate of the MOS transistor Q15 is connected to the resistor R63 and the pin 78 of the MCU, and the source is connected to the resistor R63 and grounded; The pin 1 of the relay K2 is connected to the input terminal of the diode D3 and the drain of the MOS transistor Q7, the pin 4 is connected to the current acquisition module, and the pin 5 is connected to the output terminal of the diode D3; the gate of the MOS transistor Q7 is connected to the resistor R26 and the pin 77 of the MCU, and the source is connected to the resistor R26 and grounded; The pin 1 of the relay K3 is connected to the input terminal of the diode D4 and the drain of the MOS transistor Q9, the pins 3 and 4 are connected to the current acquisition module, and the pin 5 is connected to the output terminal of the diode D4; the gate of the MOS transistor Q9 is connected to the resistor R31 and the pin 76 of the MCU, and the source is connected to the resistor R31 and grounded.

4. The finished lithium battery protection state leakage current measurement system according to claim 1, characterized in that: The current acquisition module includes a resistor R33, a resistor R34, a resistor R35, a resistor R37, a resistor R38, a resistor R39, a resistor R40, a resistor R42, a resistor R43, a resistor R45, a resistor R46, a resistor R47, a resistor R48, a resistor R49, a resistor R50, a resistor R51, a resistor R52, a resistor R53, a resistor R54, a resistor R55, a resistor R56, a resistor R57, a resistor R58, a resistor R59, a resistor R64, a resistor R66, a resistor R67, a resistor R68, a resistor R69, a resistor R70, a resistor R71, a resistor R72, an operational amplifier U5A, an operational amplifier U5B, an operational amplifier U6, an operational amplifier U8A, an operational amplifier U8B, a capacitor C26, a capacitor C27, a capacitor C29, a capacitor C31, a capacitor C32, a capacitor C34, a capacitor C35, a capacitor C36, a capacitor C38, a capacitor C39, a relay K4, a relay K5, a relay K7, a relay K8, a diode D5, a diode D6, a diode D7, a diode D8, a diode D9, a MOS transistor Q10, a MOS transistor Q11, a MOS transistor Q12, a MOS transistor Q13, a MOS transistor Q14, an opto - relay K6, a sampling resistor R28, a sampling resistor R60, a sampling resistor R61, and a multiplexer U9; Pin 5 of the operational amplifier U5B is connected to resistor R33 and capacitor C27, and pins 6 and 7 are connected to resistor R35, capacitor C26, and the ADC module; one end of resistor R34 is connected to resistor R33 and capacitor C26, and the other end is connected to resistor R40, pin 7 of operational amplifier U6, and the charge and discharge constant current source and short - circuit control module; Pin 1 of the operational amplifier U6 is connected to resistor R37, capacitor C29, and capacitor C31, pin 2 is connected to pin 8 of the multiplexer switch U9, pin 3 is connected to resistor R51, resistor R52, resistor R53, resistor R54, resistor R55, resistor R56, resistor R57, and resistor R58, pin 4 is connected to resistor R42, capacitor C31, and capacitor C35, and pin 6 is connected to resistor R35, resistor R49, and pin 7 of operational amplifier U8B; pins 4, 5, 6, 7, 12, 11, 10, 9 of the multiplexer switch U9 are respectively connected to resistor R51, resistor R52, resistor R53, resistor R54, resistor R55, resistor R56, resistor R57, and resistor R58; Pin 5 of the operational amplifier U8B is connected to resistor R39 and capacitor C32, and pin 6 is connected to resistor R40 and resistor R45; pins 1 and 2 of the operational amplifier U8A are connected to resistor R39, and pin 3 is connected to resistor R38, resistor R43, and capacitor C34; capacitor C34 is connected to resistor R43 and grounded; Pins 1 and 2 of the operational amplifier U5A are connected to resistor R50, capacitor C36, and the ADC module, and pin 3 is connected to resistor R48 and capacitor C38; resistor R48 is connected to resistor R49 and capacitor C36; Pin 1 of the relay K4 is connected to the output end of diode D5, pin 2 is connected to resistor R42, pin 3 is connected to resistor R37, pin 4 is connected to pin 2 of relay K8, pin 5 is connected to pin 3 of the sampling resistor R28, pin 6 is connected to pin 2 of the sampling resistor R60 and pin 2 of the sampling resistor R61, pin 7 is connected to pin 2 of the sampling resistor R28, and pin 8 is connected to the input end of diode D5 and the drain of the MOS transistor Q10; the source of the MOS transistor Q10 is connected to resistor R47 and grounded, and the gate is connected to resistor R46 and capacitor R47; resistor R46 is connected to pin 75 of the MCU; pin 1 of the sampling resistor R28 is connected to the charge and discharge path selection module, and pin 4 is connected to resistor R30; Pin 1 of the opto - relay K6 is connected to resistor R59 and the output end of diode D6, pin 2 is connected to the input end of diode D6 and the drain of the MOS transistor Q11, pin 3 is connected to pin 4 of relay K7 and the charge and discharge path selection module, and pin 4 is connected to pin 6 of relay K7 and the charge and discharge path selection module; one end of resistor R64 is connected to resistor R66 and the gate of the MOS transistor Q11, and the other end is connected to pin 73 of the MCU; resistor R66 is connected to the source of the MOS transistor Q11 and grounded; Pin 1 of the relay K7 is connected to the output terminal of the diode D7, pin 2 is connected to pin 2 of the relay K5, pin 3 is connected to pin 3 of the relay K5, and pin 8 is connected to the input terminal of the diode D7 and the drain of the MOS transistor Q13; One end of the resistor R67 is connected to the resistor R69 and the gate of the MOS transistor Q13, and the other end is connected to pin 72 of the MCU; The resistor R69 is connected to the source of the MOS transistor Q13 and grounded; Pin 1 of the relay K5 is connected to the output terminal of the diode D8 and the capacitor C39, pin 4 is connected to pin 1 of the sampling resistor R61, pin 5 is connected to pin 1 of the sampling resistor R60, pin 6 is connected to pin 4 of the sampling resistor R61, pin 7 is connected to pin 4 of the sampling resistor R60, and pin 8 is connected to the input terminal of the diode D8 and the drain of the MOS transistor Q12; One end of the resistor R68 is connected to the resistor R71 and the gate of the MOS transistor Q12, and the other end is connected to pin 74 of the MCU; The resistor R71 is connected to the source of the MOS transistor Q12 and grounded; Pin 1 of the relay K8 is connected to the output terminal of the diode D9, pin 2 is connected to pin 4 of the relay K4, pin 3 is connected to pin 6 of the relay K4, pin 4 is connected to pin 2 of the sampling resistor R60, pin 5 is connected to pin 2 of the sampling resistor R61, pin 6 is connected to pin 3 of the sampling resistor R60, pin 7 is connected to pin 3 of the sampling resistor R61, and pin 8 is connected to the input terminal of the diode D9 and the drain of the MOS transistor Q14; One end of the resistor R70 is connected to the resistor R72 and the gate of the MOS transistor Q14, and the other end is connected to pin 71 of the MCU; The resistor R72 is connected to the source of the MOS transistor Q14 and grounded.

5. The finished lithium battery protection state leakage current measurement system according to claim 1, characterized in that: The ADC module includes an ADC chip U7, a resistor R36, a resistor R41, a capacitor C28, a capacitor C30, and a capacitor C33; Pin 1 of the ADC chip U7 is connected to the resistor R36, the capacitor C28, and the capacitor C30, pin 2 is connected to the resistor R41, the capacitor C30, and the capacitor C33, pins 5 and 6 are connected to pins 85 and 86 of the MMCU, pin 7 is grounded, and pin 8 is connected to the DAC module.

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