CN207717931U - A kind of tester for protecting plate of lithium cell - Google Patents

Abstract

The utility model is related to a kind of tester for protecting plate of lithium cell, including Master control chip, fictitious load operating circuit, voltage detecting circuit, super-charge super-discharge protection analog voltage circuit, lithium battery group analog circuit and operating voltage switching circuit；Protection board and tester are attached by the fictitious load operating circuit, and provide detection voltage for voltage detecting circuit；The voltage detection signal of fictitious load operating circuit is delivered to Master control chip by the voltage detecting circuit；The super-charge super-discharge protection analog voltage circuit provides protection board super-charge super-discharge protection analog voltage V1；The lithium battery group analog circuit offer protection board, which is often gone here and there, works normally standby voltage V0；Voltage switching between Master control chip control operating voltage the switching circuit V1 and V0.The utility model can once test the defencive function of the overcharging or overdischarging of protection board, and operation is simplified, and test process full-automation carries out, and rapidly and efficiently saves the time.

Description

A lithium battery protection board tester

technical field

The utility model relates to a lithium battery protection board tester, in particular to an overcharge and overdischarge tester for a multi-string lithium battery pack protection board.

Background technique

Lithium battery packs have the advantages of high specific energy, long service life, high power tolerance, low self-discharge rate, light weight, high and low temperature adaptability, and environmental protection, and are widely used in various technical fields. However, due to the tenderness of the battery cell, in order to avoid irreparable damage caused by overcharging or over-discharging of the lithium battery pack during charging and discharging, it must be used with the lithium battery pack protection board, so it is necessary to overcharge and protect the lithium battery pack protection board. The over-discharge protection function is strictly controlled and tested. The overcharge or overdischarge test of the traditional multi-string lithium battery pack protection board is mostly manually tested one by one. The method has a heavy workload, cumbersome operation, and deviation and inconsistency in the test results. The multi-string lithium battery pack protection board tester on the market cannot meet the full automation of the test process, and cannot realize the test of different types of multi-string lithium battery pack protection boards.

Utility model content

In order to overcome the deficiencies of the prior art, the purpose of this utility model is to provide a multi-string lithium battery pack protection board tester, which can test the overcharge or over-discharge protection function of the multi-string lithium battery pack protection board at one time.

The technical scheme that the utility model solves its technical problem adopts is:

A lithium battery protection board tester, characterized in that it includes a main control chip, an analog load operating circuit, a voltage detection circuit, an overcharge and overdischarge protection analog voltage circuit, a lithium battery pack analog circuit, and an operating voltage switching circuit; The load working circuit connects the protection board with the tester, and provides detection voltage for the voltage detection circuit; the voltage detection circuit transmits the voltage detection signal of the analog load working circuit to the main control chip; the overcharge and overdischarge protection analog voltage The circuit provides the overcharge and overdischarge protection analog voltage V1 of the protection board for the working voltage switching circuit; the lithium battery pack analog circuit provides the normal working standby voltage V0 of each string of the protection board to realize the normal operation of the internal modules of the protection board, and the inside of the protection board The module controls the working state of the charging MOS tube and the discharging MOS tube; the lithium battery pack analog circuit simultaneously transmits the normal working standby voltage V0 of each string of the protection board to the working voltage switching circuit; the main control chip controls the operating voltage switching circuit Working state: the working voltage switching circuit realizes voltage switching between the overcharge and overdischarge protection analog voltage V1 of the protection board and the normal working standby voltage V0 of each string of the protection board.

As an improvement of the above technical solution, it also includes a display module, which is connected to the main control chip; the display module includes an analog current LED display, a qualified string number LED display and a calibration voltage LED display; the analog current The LED display screen is used to display the analog current, which is the operating current of the simulated load working circuit; the qualified string number LED display screen is used to display the number of strings currently being tested and the protection completed by the protection board processed by the main control chip The number of qualified strings tested by the board, and the working status of the tester is indicated; the calibration voltage LED display is used to display the overcharge and overdischarge protection analog voltage V1 of the protection board provided by the overcharge and overdischarge protection analog voltage circuit; when the protection When the board is in standby, the calibration voltage LED display is used to display the normal working standby voltage V0 of the first string of the protection board provided by the simulation circuit of the lithium battery pack.

As an improvement of the above technical solution, the display module is located on the panel of the tester; the panel is also provided with a protection board connection module and an operation button module; the protection board connection module includes a B-socket, a 3.81 connector and a C -/P-socket, the simulated load working circuit forms a loop with B-socket, C-/P-socket, B-wire of the protection board, and C-/P- wire of the protection board, and the simulation circuit of the lithium battery pack The working voltage switching circuit is connected to the 3.81 connector, thereby realizing the connection between the lithium battery pack analog circuit and the protection board; the operation button module includes a calibration button, a stop button, a start button and a current recovery button, and the calibration button is used for To calibrate the overcharge and overdischarge protection analog voltage V1 of the protection board provided by the overcharge and overdischarge protection analog voltage circuit, the stop button is the button for the protection board test to stop, and the start button is the button for the protection board test to start, so The above-mentioned current recovery button is used to restore the working current of the analog load working circuit.

As an improvement of the above technical solution, the tester panel includes a standard voltage input positive socket and a standard voltage input negative socket, and the standard voltage input positive socket and the standard voltage input negative socket are connected to an external power supply, which can additionally provide overcharge and overdischarge protection for the protection board Analog voltage V1; the panel of the tester is also provided with a power connection socket, a power button and a test start socket, and the power connection socket is connected with the mains through a wire rod, and the power button is the switch button of the tester test, so The test start socket is used to connect an external switch connector, and the test start socket and the start button are both starting components for the test work of the protection board.

As an improvement of the above technical solution, it includes two sets of the same main control chip, analog load working circuit, voltage detection circuit, overcharge and overdischarge protection analog voltage circuit, lithium battery pack analog circuit, working voltage switching circuit, display module, protection board Connection module, operation button module, standard voltage input positive socket, standard voltage input negative socket and test start socket.

As an improvement of the above technical solution, the analog load working circuit includes an analog load power supply BT1, a resistor RF, a C-/P- socket, a switch S1, a C-/P- wire of the protection board, a charging MOS tube of the protection board, a protection The discharge MOS tube of the board, the B-wire of the protection board, the switch S2 and the B-socket, the positive pole of the analog load power supply BT1 is connected to the first end of the switch S1 through the resistor RF, the C-/P-socket 83, and the switch S1 The second end is connected to the first end of the switch S2 through the C-/P- wire of the protection board, the charging MOS tube of the protection board, the discharge MOS tube of the protection board, and the B- wire of the protection board, and the second end of the switch S2 is connected to the B - The socket 81 is connected to the negative pole of the analog load power supply BT1.

As an improvement of the above technical solution, the voltage detection circuit includes a comparator, the positive input terminal of the comparator is connected between the resistor RF and the C-/P- socket of the analog load working circuit, and the negative input terminal of the comparator is connected through the resistor RF R70 is connected with a power supply VCC, and the output terminal of the comparator is connected with the I/O port of the single-chip microcomputer through the resistor RJ1.

As an improvement of the above technical solution, the overcharge and overdischarge protection analog voltage circuit includes an LM317 circuit, which provides an overdischarge protection analog voltage of 2.75V and an overcharge protection analog voltage of 4.25V for the working voltage switching circuit.

As an improvement of the above technical solution, the analog circuit of the lithium battery pack is externally connected to the analog power supply VCC, and the analog power supply VCC is divided into 28 groups of power supply sources in series through resistors. The voltage of the 28 groups of power supply sources is the same and equal to the normal operation of each string of the protection board. Standby voltage V0; at the same time, the normal working standby voltage V0 of each string of the protection board is sent to the 3.81 connector through the working voltage switching circuit.

As an improvement of the above technical solution, the working voltage switching circuit includes 28 groups of voltage switching circuits, each group of voltage switching circuits includes a triode, the emitter of the triode is grounded, and the base is connected to the I/O port of the single-chip microcomputer through a resistor. The collector is connected to a relay, and the relay is driven by the power supply VDD to realize the voltage switching between the overcharge and overdischarge protection analog voltage V1 of the protection board and the normal working standby voltage V0 of each string of the protection board.

The beneficial effects of the utility model are: a multi-string lithium battery pack protection board tester of the utility model can test the overcharge or over-discharge protection function of the multi-string lithium battery pack protection board at one time, and at the same time, the tester has strong compatibility , support the test of the mainstream multi-string lithium battery pack protection board in the market, and support the test of the lithium iron phosphate battery pack protection board; the operation process is simplified and one-key operation, the test process is fully automated, fast, efficient and time-saving;

There is a display module on the panel of the tester, and the test results are accurate and clear; there is also a standard voltage input socket on the panel, which can be connected to an external power supply to simulate the protection voltage of overcharge or overdischarge, and meet the protection voltage requirements of different specifications and parameters. Lithium battery pack protection board test; the tester includes two sets of the same circuit structure and operation panel, which can independently test two multi-series lithium battery pack protection boards at the same time.

Description of drawings

The specific embodiment of the utility model is further described below in conjunction with accompanying drawing:

Fig. 1 is a working principle block diagram of the present utility model;

Fig. 2 is the circuit schematic diagram of the analog load working circuit of the present utility model;

Fig. 3 is the circuit schematic diagram of the voltage detection circuit of the present utility model;

Fig. 4 is the circuit schematic diagram of the overcharge and overdischarge protection analog voltage circuit of the present utility model;

Fig. 5 is the circuit schematic diagram of the lithium battery pack simulation circuit of the present utility model;

Fig. 6 is a schematic circuit diagram of a working voltage switching circuit of the present invention;

Fig. 7 is the circuit schematic diagram of main control chip and display circuit of the present utility model;

Fig. 8 is a schematic diagram of the structure of the front panel of the utility model;

Fig. 9 is a structural schematic diagram of the back panel of the present invention.

Detailed ways

In order to enable those skilled in the art to better understand the solution of the utility model, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiment is only a part of the utility model Examples, but not all examples. Based on the embodiments of the present utility model, all other embodiments obtained by persons of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

Referring to Fig. 1, a lithium battery protection board tester is characterized in that it includes a main control chip 1, an analog load working circuit 2, a voltage detection circuit 3, an overcharge and overdischarge protection analog voltage circuit 4, and a lithium battery pack analog circuit 5 and working voltage switching circuit 6; the main control chip 1 is a single-chip microcomputer; the analog load working circuit 2 connects the protection board with the tester, and provides detection voltage for the voltage detection circuit 3; the voltage detection circuit 3 simulates The voltage detection signal of the load working circuit 2 is sent to the main control chip 1; the overcharge and overdischarge protection analog voltage circuit 4 provides the protection board overcharge and overdischarge protection analog voltage V1 for the working voltage switching circuit 6; the lithium battery pack analog The circuit 5 provides the normal working standby voltage V0 of each string of the protection board to realize the normal operation of the internal module of the protection board, and the internal module of the protection board controls the working state of the charging MOS tube and the discharging MOS tube; the lithium battery pack analog circuit 5 simultaneously The normal working standby voltage V0 of each string of the protection board is sent to the working voltage switching circuit 6; the main control chip 1 controls the working state of the working voltage switching circuit 6; the working voltage switching circuit 6 realizes the overcharge and overdischarge protection simulation of the protection board The voltage switching between the voltage V1 and the normal working standby voltage V0 of each string of protection boards; a display module 7 is also included, and the display module 7 is connected to the main control chip 1 .

Referring to Fig. 2, the analog load working circuit 2 includes an analog load power supply BT1, a resistor RF, a C-/P- socket 83, a switch S1, a C-/P- wire of a protection board, a charging MOS tube of a protection board, and a protection board The discharge MOS tube, the B-wire of the protection board, the switch S2, and the B-socket 81; the positive pole of the analog load power supply BT1 is connected to the first end of the switch S1 through the resistor RF and the C-/P-socket 83, and the second end of the switch S1 Connect the first end of the switch S2 through the C-/P- wire of the protection board, the charging MOS tube of the protection board, the discharge MOS tube of the protection board, and the B-wire of the protection board, and the second end of the switch S2 is through the B- socket 81 is connected to the negative pole of the analog load power supply BT1; the analog load working circuit 2 can simulate the real charging and discharging state of the protection board, and the internal module of the protection board controls the switching status of the charging MOS tube and the discharging MOS tube to avoid overcharging or overdischarging the protection board. irreparable damage.

With reference to Fig. 3, described voltage detection circuit 3 comprises a comparator, and the positive pole input terminal of comparator is connected between the resistance RF of analog load operating circuit 2 and C-/P- socket 83, and the negative pole input terminal of comparator is passed resistance R70 is connected with a power supply VCC, and the output terminal of the comparator is connected with the I/O port of the single-chip microcomputer through the resistance RJ1; the voltage detection circuit 3 sends the voltage detection signal of the analog load working circuit 2 to the single-chip microcomputer; the voltage detection circuit 3 During normal operation, the input terminal is low potential 0V before overcharge and overdischarge protection, and the input terminal is high level 5V after overcharge and overdischarge protection, which is equal to the voltage of the analog load power supply BT1.

With reference to Fig. 4, the core of described overcharge and overdischarge protection analog voltage circuit 4 is LM317 circuit, provides the overcharge protection analog voltage of 2.75V and the overcharge protection analog voltage of 4.25V for working voltage switching circuit 6; Over-discharge protection The analog voltage V1 can also be connected to an external power supply through the standard voltage input socket on the back panel, so as to realize any value adjustment of V1, and the protection board compatible with various over-charge and over-discharge voltage specifications completes the over-charge or over-discharge protection function test.

Referring to Figure 5, the lithium battery pack simulation circuit 5 is externally connected to the analog power supply VCC, and the analog power supply VCC is divided into 28 groups of power supply sources in series through resistors, and the voltage of the 28 groups of power supply sources is the same as 3.3V, which is equal to the normal The working standby voltage V0; the 28 groups of power supplies are also connected to the 28 groups of relays of the working voltage switching circuit 6, and connected to the 3.81 connector 82 via the relays.

With reference to Fig. 6, described working voltage switching circuit 6 comprises 28 groups of voltage switching circuits, each group of voltage switching circuits comprises a triode, the emitter of the triode is grounded, and the base is connected to the I/O port of the single-chip microcomputer through a resistor, and the set The electrodes are connected to the group of relays, and the relays are driven by the power supply VDD to control the on-off of V0, so as to realize the voltage switching between the overcharge and over-discharge protection analog voltage V1 of the protection board and the normal working standby voltage V0 of each string of the protection board; the triode When the protection board is in a normal standby state, it is in a non-conducting state, and V0 is sent to the 3.81 connector 82 through the relay; when working, the single-chip microcomputer outputs a conduction voltage to each triode one by one, and after the triode is turned on, the corresponding relays are controlled to work one by one, and then the protection board is realized. The overcharge and overdischarge functions of each string are tested one by one.

Referring to FIG. 7 , the I/O port of the single-chip microcomputer is connected with a voltage detection circuit 2 , an operating voltage switching circuit 6 and a display module 7 ; The single-chip microcomputer receives the voltage detection signal of the analog load working circuit 2 delivered by the voltage detection circuit 2, and the single-chip microcomputer processes the information and sends it to the LED display screen 72 for qualified string numbers for display, and the value of the qualified string numbers increases one by one; the single-chip microcomputer also controls the working voltage switching circuit 6 Transistor conduction state, so as to realize the voltage switching between the overcharge and overdischarge protection analog voltage V1 of the protection board and the normal working standby voltage V0 of each string of the protection board; the I/O port of the single-chip microcomputer is connected with the stop button 92, the start button 93 and the The current recovery button 94 corresponds to the normal operation of the button. After the main control chip 1 detects the action, it drives the corresponding functions of the tester to work, and then controls the working state of the tester.

Referring to Fig. 8, described display module 7 comprises analog current LED display screen 71, qualified serial number LED display screen 72 and calibration voltage LED display screen 73; Described analog current LED display screen 71 is used for displaying analog current, and described analog current For simulating the operating current of the load working circuit 2, the qualified string number LED display screen 72 is used to display the number of strings currently being tested by the protection board processed by the main control chip 1 and the number of qualified strings that have completed the protection board test, and to test The working status of the instrument is indicated; when working, the blue LED light of the qualified string number LED display 72 will always flash, and when the work is over, the qualified string number LED display screen 72 is always bright red LED light; the calibration voltage LED display The screen 73 is used to display the overcharge and overdischarge protection analog voltage circuit 4 or the protection board overcharge and overdischarge protection analog voltage V1 provided by the external power supply input of the standard voltage input socket on the back panel; when the protection board is on standby, the calibration voltage LED display screen 73 is used to display the first string of normal working standby voltage V0 of the protection board provided by the lithium battery pack analog circuit 5; the display module 7 is located in the middle of the front panel of the tester, which is convenient for the user to observe the test results; the analog current The LED display screen 71 , the qualified string number LED display screen 72 and the calibration voltage LED display screen 73 are sequentially arranged in horizontal rows on the display module 7 . The front panel of the tester also includes a protection board connection module 8 and an operation button module 9; the protection board connection module 8 includes a B-socket 81, a 3.81 connector 82 and a C-/P-socket 83, and the simulated load The working circuit 2 forms a loop with the B-socket 81, the C-/P-socket 83, the B-wire of the protection board, and the C-/P- wire of the protection board, and the lithium battery pack simulation circuit 5 is connected to the voltage switching circuit 6 Finally, the 3.81 connector 82 is connected to the protection board through the signal connection line; the protection board connection module 8 is located at the lower position of the front panel of the tester, and the B-socket 81, 3.81 connector 82 and C-/P -The sockets 83 are arranged horizontally on the protection board connection module 8 in turn; the B-socket 81 is connected to the B-wire of the protection board, and the 3.81 connector 82 connects the tester and the protection board through a signal line, and the C- The /P-socket 83 is connected to the C-/P-wire of the protection board. The operation button module 9 includes a calibration button 91, a stop button 92, a start button 93 and a current recovery button 94, and the calibration button 91 is provided for the input of the overcharge and overdischarge protection analog voltage circuit 4 or the standard voltage socket on the back panel. The overcharge and overdischarge protection analog voltage V1 of the protection board is calibrated; press the calibration button 91, and the value of the protection analog voltage will be displayed on the analog voltage LED display 73; the stop button 92 provides live operation of the multi-string lithium battery pack protection board When the test encounters an unexpected and unpredictable emergency, press the button and the tester will stop working immediately and cut off all test actions to ensure the safety of people, machines and products; the start button 93 is to start protection Board overcharge and overdischarge protection function test button, after the protection board is correctly connected to the tester, press this button to start the overcharge and overdischarge function test of each string of the protection board; the current recovery button 94 is used to restore the analog load working circuit 2 working current; the natural state of the current recovery button 94 is a normally closed switch, after the analog current LED display 71 shows no current after connecting the protection board, press this button to cut off the protection board C-/P- wire and C- The connection between the /P-socket 83 disconnects the analog load working circuit 2, and provides the analog operating current for the protection board; the operation button module 9 is located on both sides of the front panel of the tester, and the calibration button 91 and the stop button 92 , the start button 93 and the current recovery button 94 are sequentially arranged in vertical rows on the operation button module 9 .

Referring to Figure 9, the tester panel includes a standard voltage input positive socket 12 and a standard voltage input negative socket 13, the standard voltage input positive socket 12 and the standard voltage input negative socket 13 are connected to an external power supply, and can simultaneously provide different overcharge and overdischarge voltage specifications The overcharge and overdischarge protection analog voltage V1 of the protection board; the back panel of the tester is also provided with a power connection socket 10, a power button 11 and a test start socket 14, and the power connection socket 10 is located at the lower right side of the back panel, Connect the mains of 220V/50Hz to supply power to the multi-string lithium battery pack protection board tester; the power button 11 is located above the power connection socket 10 to control the working switch state of the tester; the test start socket 14 can be externally connected to other Type switch connectors, such as other types of switch connectors such as foot switches, the test start socket 14 and the start button 93 are the same starting components for the protection board test work; the standard voltage input positive socket 12, the standard voltage input negative socket 13 and the test start socket 14 are arranged in longitudinal rows in the middle of the back panel.

The tester of the utility model includes two sets of the same main control chip 1, an analog load working circuit 2, a voltage detection circuit 3, an overcharge and overdischarge protection analog voltage circuit 4, a lithium battery pack analog circuit 5, an operating voltage switching circuit 6, Display module 7, protection board connection module 8, operation button module 9, standard voltage input positive pole socket 12, standard voltage input negative pole socket 13 and test start socket 14, can test two groups of protection boards at the same time, two groups work independently and mutually Do not interfere.

For the overcharge and overdischarge test of the multi-string lithium battery pack protection board, the power supply connection socket 10 is connected to the mains power of 220V/50Hz, and the power button 11 is pressed. After the tester is turned on, the protection board and the The tester is connected correctly, the B- wire of the protection board is connected to the B- socket 81 through the connecting wire, the serial port of the protection board is connected to the 3.81 connector 82 through the signal line, and the C-/P- wire of the protection board is connected to the C-/P- The socket 83 is connected. After the connection is completed, the internal lithium battery pack analog circuit 5 of the tester provides the normal working standby voltage V0 for each string of the protection board, and then the internal control module of the protection board is powered to drive the charging MOS tube and the discharging MOS tube to open normally, so that the protection board Board B-wire, protection board C-/P-wire, B-socket 81, C-/P-socket 83 form a closed loop, the tester is equipped with an analog load working circuit 2, and the working current passes through C-/P-socket 83 output, through the protection board C-/P-wire input into the inside of the protection board, flow through the charging MOS tube, discharge MOS tube inside the protection board, pass through the protection board B-wire, and finally flow back to the internal simulation load of the tester through the B-socket 81 The working circuit 2 constitutes the closed loop of the internal analog load working circuit 2 of the tester. Simultaneously, the analog current LED display screen 71 of the tester will display the working current of the current internal analog load working circuit 2 of the tester. After the overcharge and overdischarge protection analog voltage V1 provided by the overcharge and overdischarge analog protection voltage circuit 4 or input by the external power supply on the back panel meets the protection board’s overcharge and overdischarge protection voltage protection specification range, press the start button 93, and the working voltage switching circuit 6 The relay switches the normal working standby voltage V0 of each string of the protection board to the overcharge and overdischarge protection analog voltage V1 one by one. Since V1 reaches the overcharge and overdischarge protection voltage of the protection board, the internal control modules of the protection board are immediately shut down respectively. Or the corresponding MOS tube inside the protection board under the over-discharge function makes the analog load working circuit 2 close the output, so that the current and voltage of the C-/P- socket 83 change, and the voltage detection element of the voltage detection circuit 3 detects the C- After the voltage of /P- socket 83 terminal changes, the main control chip 1 processes the protection board that is considered to be switched to the overcharge and overdischarge protection voltage V1. The current overcharge and overdischarge protection function of the string is normal. The discharge tube or discharge MOS tube is closed. When the real external charger or load is connected, the external charger of the lithium battery pack cannot continue to charge the lithium battery pack, and the lithium battery pack cannot discharge the external real load circuit. The series overcharge and overdischarge protection function test is completed, the number of qualified series LED display 82 displays the number "1", and then the main control chip 1 automatically performs the test of the overcharge and overdischarge protection function of the next series of the protection board, otherwise the tester stops the test Working and qualified string number LED display 82 is always red, showing the currently tested qualified string number, and indicating a certain string number with poor overcharge or over-discharge function, for example, in the protection of 13 string specifications board carried out When the charging or over-discharging function is tested, if the LED display screen 82 of the qualified string number displays the number "9" and the red light is on, it indicates that the overcharge or over-discharge protection function of the first 9 strings of the protection board is normal, and at the same time, the 10th string of the protection board is over-discharged. If the charging or over-discharging function is abnormal, test the over-charging or over-discharging protection function of each string of the protection board in turn until the test of all the strings of the entire protection board is completed. Otherwise, the protective board product currently being tested is a defective product.

In summary, the above embodiments are only used to illustrate the technical solutions of the present utility model, rather than to limit it; although the utility model has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand; it still The technical solutions recorded in the foregoing embodiments can be modified, or equivalent replacements can be made to many of the technical features, and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention. .

Claims (10)

1. A lithium battery protection board tester, characterized in that: comprise main control chip (1), simulated load working circuit (2), voltage detection circuit (3), overcharge and overdischarge protection analog voltage circuit (4), Lithium battery pack simulation circuit (5) and working voltage switching circuit (6); The simulated load working circuit (2) connects the protection board with the tester, and provides a detection voltage for the voltage detection circuit (3); The voltage detection circuit (3) transmits the voltage detection signal of the analog load working circuit (2) to the main control chip (1); The overcharge and overdischarge protection analog voltage circuit (4) provides the protection board overcharge and overdischarge protection analog voltage V1 for the working voltage switching circuit (6); The lithium battery pack simulation circuit (5) provides the normal working standby voltage V0 of each string of the protection board to realize the normal operation of the internal module of the protection board, and the internal module of the protection board controls the working state of the charging MOS tube and the discharging MOS tube; the described The lithium battery pack simulation circuit (5) simultaneously transmits the normal working standby voltage V0 of each string of the protection board to the working voltage switching circuit (6); The main control chip (1) controls the working state of the working voltage switching circuit (6); The working voltage switching circuit (6) realizes voltage switching between the overcharge and overdischarge protection analog voltage V1 of the protection board and the normal working standby voltage V0 of each string of the protection board. 2. A lithium battery protection board tester according to claim 1, characterized in that: it also includes a display module (7), and the display module (7) is connected to the main control chip (1); the display module (7) comprise analog current LED display screen (71), qualified serial number LED display screen (72) and calibration voltage LED display screen (73); Described analog current LED display screen (71) is used for displaying analog current, described The simulated current is the working current of the simulated load working circuit (2); the qualified string number LED display screen (72) is used to display the number of strings currently being tested and the protection board test completed by the protection board processed by the main control chip (1) The number of qualified strings, and the working status of the tester is indicated; the calibration voltage LED display (73) is used to display the overcharge and overdischarge protection analog voltage of the protection board provided by the overcharge and overdischarge protection analog voltage circuit (4) V1; when the protection board is on standby, the calibration voltage LED display screen (73) is used to display the first string of normal working standby voltage V0 of the protection board provided by the lithium battery pack analog circuit (5). 3. A lithium battery protection board tester according to claim 2, characterized in that: the display module (7) is located on the panel of the tester; the panel is also provided with a protection board connection module (8) and an operation button module (9); the protection board connection module (8) includes a B-socket (81), a 3.81 connector (82) and a C-/P-socket (83), and the analog load working circuit (2 ) the B-socket (81), C-/P-socket (83), the B-wire of the protection board, the C-/P- wire of the protection board constitute a loop, and the lithium battery pack simulation circuit (5) is operated The voltage switching circuit (6) is connected with the 3.81 connector (82), thereby realizing the connection between the lithium battery pack simulation circuit (5) and the protection board; the operation button module (9) includes a calibration button (91), a stop button (92), start button (93) and current recovery button (94), described calibration button (91) is used for the overcharge and overdischarge protection analog voltage V1 of the protection board that overcharge and overdischarge protection analog voltage circuit (4) provides Calibrate, the stop button (92) is the button that the protection board test stops, the start button (93) is the button that the protection board test starts, and the current recovery button (94) is used to restore the simulated load working circuit (2 ) working current. 4. A lithium battery protection board tester according to claim 1, characterized in that: the tester panel includes a standard voltage input positive pole socket (12) and a standard voltage input negative pole socket (13), the standard voltage input positive pole The socket (12) and the standard voltage input negative pole socket (13) are externally connected to the power supply, which can provide the overcharge and overdischarge protection analog voltage V1 of the protection board simultaneously; the panel of the tester is also provided with a power connection socket (10), a power button ( 11) and test start socket (14), described power connection socket (10) links to each other with mains through wire rod, and described power button (11) is the switch button that tester tests, and described test start socket (14) is used for The external switch connector, the test start socket (14) and the start button (93) are both start components of the protection board test work. 5. A lithium battery protection board tester according to claim 4, characterized in that: it includes two groups of identical main control chips (1), simulated load working circuit (2), voltage detection circuit (3), over Charge and over-discharge protection analog voltage circuit (4), lithium battery pack analog circuit (5), working voltage switching circuit (6), display module (7), protection board connection module (8), operation button module (9), standard Voltage input positive pole socket (12), standard voltage input negative pole socket (13) and test start socket (14). 6. A lithium battery protection board tester according to claim 1, characterized in that: said simulated load working circuit (2) includes simulated load power supply BT1, resistor RF, C-/P-socket (83), Switch S1, C-/P-wire of the protection board, charging MOS tube of the protection board, discharge MOS tube of the protection board, B-wire of the protection board, switch S2 and B-socket (81), the analog load power BT1 The positive electrode of the switch S1 is connected to the first end of the switch S1 through the resistor RF and the C-/P- socket 83, and the second end of the switch S1 is connected to the C-/P- wire of the protection board, the charging MOS tube of the protection board, and the discharge MOS of the protection board. The B-wire of the tube and the protection board is connected to the first end of the switch S2, and the second end of the switch S2 is connected to the negative pole of the analog load power supply BT1 through the B-socket 81. 7. A lithium battery protection board tester according to claim 6, characterized in that: the voltage detection circuit (3) includes a comparator, and the positive input terminal of the comparator is connected to the analog load working circuit (2) Between the resistor RF and the C-/P- socket (83), the negative input terminal of the comparator is connected with a power supply VCC through the resistor R70, and the output terminal of the comparator is connected with the I/O port of the single-chip microcomputer through the resistor RJ1. 8. A lithium battery protection board tester according to claim 1, characterized in that: the overcharge and overdischarge protection analog voltage circuit (4) includes an LM317 circuit, which provides 2.75V for the working voltage switching circuit (6) Over-discharge protection analog voltage and 4.25V over-charge protection analog voltage. 9. A lithium battery protection board tester according to claim 3, characterized in that: the lithium battery pack simulation circuit (5) is externally connected to an analog power supply VCC, and the analog power supply VCC is divided into 28 groups of power supply sources in series through resistors, The voltages of the 28 groups of power supplies are the same and equal to the normal working standby voltage V0 of each string of protection boards; at the same time, the normal working standby voltage V0 of each string of protection boards is sent to the 3.81 connector (82) through the working voltage switching circuit (6). 10. A lithium battery protection board tester according to claim 1, characterized in that: the working voltage switching circuit (6) includes 28 groups of voltage switching circuits, each group of voltage switching circuits includes a triode, and the triode The emitter is grounded, the base is connected to the I/O port of the microcontroller through a resistor, and the collector is connected to a relay. The relay is driven by the power supply VDD to realize the overcharge and overdischarge protection analog voltage V1 of the protection board and each string of the protection board. Voltage switching between normal working standby voltage V0.