Relay sticking detection circuit and battery management system

Abstract

The application discloses a kind of relay sticking detection circuits and battery management system.Circuit includes: the input end of first voltage division filter module is connected vehicle battery pack, the first end and the second end of first voltage division filter module are connected the first end of relay switch, the output end of first voltage division filter module is connected the first input end of hysteresis comparison module;The input end of second voltage division filter module is connected vehicle battery pack, the first end and the second end of second voltage division filter module are connected the second end of relay switch, the third end of second voltage division filter module is connected ground signal, the output end of second voltage division filter module is connected the second input end of hysteresis comparison module, the first end of hysteresis comparison module is connected the first end of relay switch;The input end of isolation module is connected the output end of hysteresis comparison module, the output end of isolation module is connected processing unit.By the technical scheme of the application, a small volume, low cost, structure and diagnostic strategy are simple sticking detection circuit.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobile battery management, and in particular to a relay sticking detection circuit and a battery management system. BACKGROUND

[0002] One of the main factors affecting the safety of the power battery of an electric vehicle is the sticking problem of the relay on the charging or discharging circuit of the power battery. If the relay sticks, it is easy to cause over-discharge, over-temperature and other problems of the power battery, and in severe cases, even cause fire, explosion and other serious accidents, which seriously threaten personal safety.

[0003] In related technologies, the detection of relay sticking usually needs to detect the branch selection unit, the high-voltage side ADC (Analog to Digital Converter) acquisition chip and the isolation chip to transmit the detection signal to the low-voltage side MCU (Multi Control Unit), which occupies a large space and has high production cost, and the diagnosis strategy is complicated. SUMMARY

[0004] The present application provides a relay sticking detection circuit and a battery management system to realize a relay sticking detection circuit with small size, low cost and simple structure and diagnosis strategy.

[0005] According to an aspect of the present application, a relay sticking detection circuit is provided, comprising: a first voltage division filtering module, a second voltage division filtering module, a hysteresis comparison module, an isolation module and a processing unit.

[0006] The input end of the first voltage division filtering module is connected to a vehicle battery pack, the first end and the second end of the first voltage division filtering module are connected to the first end of a relay switch, and the output end of the first voltage division filtering module is connected to the first input end of the hysteresis comparison module.

[0007] The input end of the second voltage division filtering module is connected to the vehicle battery pack, the first end and the second end of the second voltage division filtering module are connected to the second end and the first end of the relay switch respectively, the third end of the second voltage division filtering module is connected to a ground signal, the output end of the second voltage division filtering module is connected to the second input end of the hysteresis comparison module, and the first end of the hysteresis comparison module is connected to the first end of the relay switch.

[0008] The input end of the isolation module is connected to the output end of the hysteresis comparison module, the first end of the isolation module is connected to a first power supply, the second end and the third end of the isolation module are connected to the ground signal, the output end of the isolation module is connected to the processing unit, and the processing unit is used to determine the sticking state of the relay switch according to the working state of the isolation module.

[0009] Optionally, the hysteresis comparison module comprises a comparator, a first resistor and a first capacitor;

[0010] The first input terminal of the comparator is the first input terminal of the hysteresis comparison module, the second input terminal of the comparator is the second input terminal of the hysteresis comparison module, and the output terminal of the comparator is the output terminal of the hysteresis comparison module.

[0011] The first terminal of the first resistor is connected to the first input terminal of the comparator, the second terminal of the first resistor is connected to the output terminal of the comparator, the second terminal of the first resistor is connected to the first capacitor, and the second terminal of the first capacitor is the first terminal of the hysteresis comparison module.

[0012] Optionally, the isolation module comprises an optocoupler isolation switch, a second resistor and a third resistor.

[0013] The first terminal of the second resistor is the input terminal of the isolation module, and the second terminal of the second resistor is connected to the first terminal of the optocoupler isolation switch.

[0014] The second terminal and the third terminal of the optocoupler isolation switch are the second terminal and the third terminal of the isolation module, and the fourth terminal of the optocoupler isolation switch is the output terminal of the isolation module.

[0015] The first terminal of the third resistor is connected to the fourth terminal of the optocoupler isolation switch, and the second terminal of the third resistor is the first terminal of the isolation module.

[0016] Optionally, the first voltage division filtering module comprises a first voltage division unit and a first filtering unit.

[0017] The first terminal of the first voltage division unit is the input terminal of the first voltage division filtering module, and the second terminal of the first voltage division unit is the first terminal of the first voltage division filtering unit.

[0018] The first terminal of the first filtering unit is connected to the third terminal of the first voltage division unit, the second terminal of the first filtering unit is the output terminal of the first voltage division filtering unit, and the third terminal of the first filtering unit is the second terminal of the first voltage division filtering unit.

[0019] Optionally, the first voltage division unit comprises a fourth resistor and a fifth resistor.

[0020] The first terminal of the fourth resistor is the first terminal of the first voltage division unit, and the second terminal of the fourth resistor is the third terminal of the first voltage division unit.

[0021] The first end of the fifth resistor is connected to the second end of the fourth resistor, and the second end of the fifth resistor serves as the second end of the first voltage division unit.

[0022] Optionally, the first filter unit comprises a sixth resistor and a second capacitor.

[0023] The first end of the sixth resistor serves as the first end of the first filter unit, and the second end of the sixth resistor serves as the second end of the first filter unit.

[0024] The first end of the second capacitor is connected to the second end of the sixth resistor, and the second end of the second capacitor serves as the third end of the first filter unit.

[0025] Optionally, the second voltage division filter module comprises a second voltage division unit and a second filter unit.

[0026] The first end of the second voltage division unit serves as the input end of the second voltage division filter module, the second end of the second voltage division unit serves as the first end of the second voltage division filter module, and the fourth end of the second voltage division unit serves as the third end of the second voltage division filter module.

[0027] The first end of the second filter unit is connected to the third end of the second voltage division unit, the second end of the second filter unit serves as the output end of the second voltage division filter unit, and the third end of the second filter unit serves as the second end of the second voltage division filter unit.

[0028] Optionally, the second voltage division unit comprises a seventh resistor, an eighth resistor and a ninth resistor.

[0029] The first end of the seventh resistor serves as the first end of the second voltage division unit, and the second end of the seventh resistor serves as the third end of the second voltage division unit.

[0030] The first end of the eighth resistor is connected to the second end of the seventh resistor, and the second end of the eighth resistor serves as the second end of the second voltage division unit.

[0031] The first end of the ninth resistor is connected to the second end of the seventh resistor, and the second end of the ninth resistor serves as the fourth end of the second voltage division unit.

[0032] The resistance value of the ninth resistor is greater than the resistance value of the fifth resistor in the first voltage division unit of the relay sticking detection circuit, and the resistance value of the eighth resistor is less than the resistance value of the fifth resistor.

[0033] Optionally, the second filter unit comprises a tenth resistor and a third capacitor.

[0034] The first end of the tenth resistor is the first end of the second filter unit, and the second end of the tenth resistor is the second end of the second filter unit.

[0035] The first end of the third capacitor is connected to the second end of the tenth resistor, and the second end of the third capacitor is the third end of the second filter unit.

[0036] According to another aspect of the present application, a battery management system is provided, comprising the relay sticking detection circuit according to the above aspect.

[0037] The technical scheme of the embodiment of the present application, by setting the relay sticking detection circuit comprising a first voltage division filter module, a second voltage division filter module, a hysteresis comparison module, an isolation module and a processing unit, the input end of the first voltage division filter module is connected to the vehicle battery pack, the first end and the second end of the first voltage division filter module are connected to the first end of the relay switch, and the output end of the first voltage division filter module is connected to the first input end of the hysteresis comparison module; the input end of the second voltage division filter module is connected to the vehicle battery pack, the first end and the second end of the second voltage division filter module are connected to the second end of the relay switch, the third end of the second voltage division filter module is connected to the ground signal, the output end of the second voltage division filter module is connected to the second input end of the hysteresis comparison module, and the first end of the hysteresis comparison module is connected to the first end of the relay switch; the input end of the isolation module is connected to the output end of the hysteresis comparison module, the first end of the isolation module is connected to the first power supply, the second end and the third end of the isolation module are connected to the ground signal, and the output end of the isolation module is connected to the processing unit, and the processing unit is used to determine the sticking state of the relay switch according to the working state of the isolation module; accordingly, a relay sticking detection circuit with small size, low cost, simple structure and diagnosis strategy is realized.

[0038] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present application, nor is it intended to limit the scope of the present application. Other features of the present application will become apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0040] Figure 1 is a structural schematic diagram of a relay sticking detection circuit provided by the embodiment of the present application;

[0041] Figure 2This is a schematic diagram of the isolation module in another relay adhesion detection circuit provided in this embodiment of the invention;

[0042] Figure 3 This is a schematic diagram of the structure of some modules in another relay adhesion detection circuit provided in an embodiment of the present invention;

[0043] Figure 4 This is a schematic diagram illustrating the working principle of the hysteresis comparator provided in an embodiment of the present invention;

[0044] Figure 5 This is a simulation diagram of the hysteresis comparator provided in this invention. Detailed Implementation

[0045] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0046] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0047] Figure 1 This is a schematic diagram of a relay adhesion detection circuit provided in an embodiment of the present invention. (Reference) Figure 1 The relay adhesion detection circuit includes: a first voltage divider filter module 10, a second voltage divider filter module 20, a hysteresis comparison module 30, an isolation module 40, and a processing unit 50;

[0048] The input terminal of the first voltage divider filter module 10 is connected to the vehicle battery pack, the first and second terminals of the first voltage divider filter module 10 are connected to the first terminal of the relay switch S, and the output terminal of the first voltage divider filter module 10 is connected to the first input terminal of the hysteresis comparison module 30.

[0049] The input end of the second voltage division filtering module 20 is connected with the vehicle battery pack, the first end and the second end of the second voltage division filtering module 20 are respectively connected with the second end and the first end of the relay switch S, the third end of the second voltage division filtering module 20 is connected with the ground signal, and the output end of the second voltage division filtering module 20 is connected with the second input end of the hysteresis comparison module 30, and the first end of the hysteresis comparison module 30 is connected with the first end of the relay switch S.

[0050] The input end of the isolation module 40 is connected with the output end of the hysteresis comparison module 30, the first end of the isolation module 40 is connected with the first power supply (5V), the second end and the third end of the isolation module 40 are connected with the ground signal, and the output end of the isolation module 40 is connected with the processing unit 50, and the processing unit 50 is used for determining the sticking state of the relay switch according to the working state of the isolation module 40.

[0051] Specifically, the voltage between the two ends of the vehicle battery pack is denoted as U. The input end of the first voltage division filtering module 10 and the input end of the second voltage division filtering module 20 can be connected with the positive electrode of the vehicle battery pack, and the negative electrode of the vehicle battery pack and the first end of the relay switch S can be connected with the ground signal. The ground signal can be a reference ground or a real ground. The first voltage division filtering module 10 and the second voltage division filtering module 20 both have voltage division and filtering functions, which can be realized by using voltage division resistors for voltage division and RC circuits for filtering. The hysteresis comparison module 30 can include a hysteresis comparator, the isolation module 40 can include an optical coupling isolation, and the processing unit 50 can include an MCU.

[0052] The technical scheme of the embodiment of the application, the first voltage division filtering module 10 and the second voltage division filtering module 20 respectively constitute voltage division networks and filter the signals of the first input end and the second input end of the hysteresis comparison module 30. The hysteresis comparison module 30 controls the working state of the isolation module 40 by comparing the voltages of the first input end and the second input end, for example, controls the working state of the isolation module 40 to be on or the working state to be off. The processing unit 50 determines whether the relay switch S is stuck according to the working state of the isolation module 40, that is, determines whether the relay switch S is not completely closed when it is closed or not completely opened when it is opened. For example, if the working state of the isolation module 40 is on, the processing unit 50 determines that the relay switch S is in the closed state, and if the working state of the isolation module 40 is off, the processing unit 50 determines that the relay switch S is not stuck. As can be seen, the relay sticking detection circuit provided by the embodiment of the application does not need to transmit the detection signal to the low-voltage side MCU by using the detection branch selection unit, the high-voltage side ADC acquisition chip and the isolation chip, and each module can be composed of conventional simple components, so that the relay sticking detection circuit is small in size, low in cost and simple in structure and diagnosis strategy.

[0053] In the embodiment of the present application, the first voltage division filter module 10, the second voltage division filter module 20, the hysteresis comparison module 30 and the isolation module 40 can have various structures, which are described below as examples, but not as a limitation of the present application.

[0054] Figure 2 is another structure diagram of the isolation module 40 in the relay sticking detection circuit provided by the embodiment of the present application. Referring to Figure 2 Optionally, the isolation module 40 includes an optocoupler isolation switch U2, a second resistor R2 and a third resistor R3.

[0055] The first end of the second resistor R2 is the input end of the isolation module 40, and the second end of the second resistor R2 is connected to the first end of the optocoupler isolation switch U2.

[0056] The second end and the third end of the optocoupler isolation switch U2 are the second end and the third end of the isolation module 40, and the fourth end of the optocoupler isolation switch U2 is the output end of the isolation module 40.

[0057] The first end of the third resistor R3 is connected to the fourth end of the optocoupler isolation switch U2, and the second end of the third resistor R3 is the first end of the isolation module 40.

[0058] For example, the second end of the optocoupler isolation switch U2 can be the cathode of the light-emitting diode in the internal structure of the optocoupler isolation switch U2, and the third end of the optocoupler isolation switch U2 can be one of the ends of the switching element in the internal structure of the optocoupler isolation switch U2. For example, if the optocoupler isolation switch U2 is in an off state, the optocoupler isolation switch U2 outputs a high level to the MCU, and the MCU can determine that the relay switch S is not stuck. If the optocoupler isolation switch U2 is on, the optocoupler isolation switch U2 outputs a low level to the MCU, and the MCU can determine that the relay switch S is in a closed state.

[0059] Figure 3 is another structure diagram of part of the modules in the relay sticking detection circuit provided by the embodiment of the present application. Referring to Figure 3 Optionally, the hysteresis comparison module 30 includes a comparator U1, a first resistor R1 and a first capacitor C1.

[0060] The first input end of the comparator U1 is the first input end of the hysteresis comparison module 30, the second input end of the comparator U1 is the second input end of the hysteresis comparison module 30, and the output end of the comparator U1 is the output end of the hysteresis comparison module 30.

[0061] The first end of the first resistor R1 is connected to the first input end of the comparator U1, the second end of the first resistor R1 is connected to the output end of the comparator, the second end of the first resistor R1 is connected to the first capacitor C1, and the second end of the first capacitor C1 is the first end of the hysteresis comparison module 30.

[0062] Specifically, the first input end of the comparator can be the in-phase input end "+", and the second input end of the comparator U1 can be the reverse input end "-". The comparator U1 and the first resistor R1 constitute a hysteresis comparator. Compared with a common comparator, the hysteresis comparator can widen the voltage threshold range by adjusting the first resistor R1, and when the input voltage changes, as long as the voltage change amount does not exceed the voltage threshold range, the output will not jump.

[0063] Exemplarily, Figure 4 is a working principle diagram of the hysteresis comparator provided by the embodiment of the application, the reference voltage is 12V, the input voltage is a 24V triangular wave, the reverse input end and the output end are connected to a double-channel oscilloscope, and the simulation result is as shown in Figure 5 , that is Figure 5 is a working simulation diagram of the hysteresis comparator provided by the embodiment of the application.

[0064] Referring to Figure 5 , the dashed curve is a 24V triangular wave input waveform, and the solid curve is a hysteresis comparator output waveform. It is not difficult to see from the waveform measurement that the threshold voltage of the hysteresis comparator is UTL (lower threshold voltage) = 8.856 and UTH (upper threshold voltage) = 15.209, that is, when the input voltage value increases to 8.856V, the comparator output jumps from high to low; when the input voltage decreases to 15.209V, the comparator output jumps from low to high. The output jump range is widened from 12V to ΔU, that is, [UTL, UTH], and as long as the interference near the jump voltage value does not exceed ΔU after the output state is converted, the output voltage value will be stable. Therefore, the technical scheme of the embodiment of the application adopts the hysteresis comparator to reduce the misjudgment caused by the input end voltage fluctuation, and improves the anti-interference ability of the circuit and the reliability of the sticking diagnosis.

[0065] As an embodiment of the application, optionally, the first voltage division filtering module 10 comprises a first voltage division unit and a first filtering unit, the first voltage division unit constitutes a voltage division network of the first input end of the hysteresis comparison module 30, and the first filtering unit filters the signal of the first input end of the hysteresis comparison module 30;

[0066] The first end of the first voltage division unit is the input end of the first voltage division filtering module 10, and the second end of the first voltage division unit is the first end of the first voltage division filtering unit.

[0067] The first end of the first filter unit is connected with the third end of the first voltage division unit, the second end of the first filter unit is the output end of the first voltage division filter unit, and the third end of the first filter unit is the second end of the first voltage division filter unit.

[0068] With reference to the foregoing Figure 3 Optionally, the first voltage division unit comprises a fourth resistor R4 and a fifth resistor R5.

[0069] The first end of the fourth resistor R4 is the first end of the first voltage division unit, and the second end of the fourth resistor R4 is the third end of the first voltage division unit.

[0070] The first end of the fifth resistor R5 is connected with the second end of the fourth resistor R4, and the second end of the fifth resistor R5 is the second end of the first voltage division unit.

[0071] With reference to the foregoing Figure 3 Optionally, the first filter unit comprises a sixth resistor R6 and a second capacitor C2.

[0072] The first end of the sixth resistor R6 is the first end of the first filter unit, and the second end of the sixth resistor R6 is the second end of the first filter unit.

[0073] The first end of the second capacitor C2 is connected with the second end of the sixth resistor R6, and the second end of the second capacitor C2 is the third end of the first filter unit.

[0074] As an embodiment of the present application, optionally, the second voltage division filter module 20 comprises a second voltage division unit and a second filter unit, the second voltage division unit constitutes a voltage division network of the second input end of the hysteresis comparison module 30, and the second filter unit filters the signal of the second input end of the hysteresis comparison module 30.

[0075] The first end of the second voltage division unit is the input end of the second voltage division filter module 20, the second end of the second voltage division unit is the first end of the second voltage division filter module 20, and the fourth end of the second voltage division unit is the third end of the second voltage division filter module 20.

[0076] The first end of the second filter unit is connected with the third end of the second voltage division unit, the second end of the second filter unit is the output end of the second voltage division filter unit, and the third end of the second filter unit is the second end of the second voltage division filter unit.

[0077] With reference to the foregoing Figure 3 Optionally, the second voltage division unit comprises a seventh resistor R7, an eighth resistor R8 and a ninth resistor R9.

[0078] The first end of the seventh resistor R7 is the first end of the second voltage division unit, and the second end of the seventh resistor R7 is the third end of the second voltage division unit.

[0079] The first end of the eighth resistor R8 is connected to the second end of the seventh resistor R7, and the second end of the eighth resistor R8 is the second end of the second voltage division unit;

[0080] The first end of the ninth resistor R9 is connected to the second end of the seventh resistor R7, and the second end of the ninth resistor R9 is the fourth end of the second voltage division unit;

[0081] The resistance value of the ninth resistor R9 is greater than the resistance value of the fifth resistor R5 in the first voltage division unit of the relay sticking detection circuit, and the resistance value of the eighth resistor R8 is less than the resistance value of the fifth resistor R5.

[0082] Continuing to refer to Figure 3 Optionally, the second filtering unit comprises a tenth resistor R10 and a third capacitor C3.

[0083] The first end of the tenth resistor R10 is the first end of the second filtering unit, and the second end of the tenth resistor R10 is the second end of the second filtering unit.

[0084] The first end of the third capacitor C3 is connected to the second end of the tenth resistor R10, and the second end of the third capacitor C3 is the third end of the second filtering unit.

[0085] The following will be described in combination with Figure 2 and Figure 3 The working principle of the relay sticking detection circuit provided by the embodiment of the application will be described.

[0086] One end of the fourth resistor R4 is connected to the positive bus of the vehicle battery pack, the other end is connected to the fifth resistor R5 connected to the negative bus of the battery pack to form a voltage division network 1, and the seventh resistor R7, the eighth resistor R8 and the ninth resistor R9 are connected to the outside of the relay, i.e. the load end, to form a voltage division network 2; wherein the ninth resistor R9 is much greater than the fifth resistor R5, and the eighth resistor R8 is much smaller than the fifth resistor R5; the input ends of the comparator U1 are filtered by RC circuits, and the output voltage is Uo; a hysteresis comparator is used, the on-off of the optocoupler isolation switch U2 is controlled by comparing the voltages at the same direction and reverse direction input ends of U1, and then the state of the relay is judged.

[0087] When the relay switch S is disconnected, the voltage at point A is The voltage at point B is Since R9 is much greater than R5, U B > U A At this time, the comparator U1 outputs a low level, the optocoupler isolation switch U2 is in an off state, and a high level is output to the MCU, so it can be judged that the relay is not sticking. When the relay switch S is closed, the voltage at point A is The voltage at point B is Since R8 is much smaller than R5, U ′B <U ′ A At this time, the comparator U1 output level is high, the optocoupler isolation switch U2 is turned on, and a low level is output to the MCU, so that it can be judged that the relay is in the closed state. Wherein, U is the voltage between the two ends of the vehicle battery pack;R9 / / R8 is the resistance value when the ninth resistor R9 and the eighth resistor R8 are connected in parallel,

[0088] The technical scheme of the embodiment of the application compares the relay terminal voltage by using the comparator U1 to output high and low levels to control the optocoupler isolation switch U2, directly transmits the detection signal to the low-voltage side MCU to determine whether the relay is stuck, and optimizes the detection strategy;The hysteresis comparator and the port are filtered by the RC circuit, which can reduce the influence of the input port voltage interference and fluctuation, and improve the reliability of the sticking diagnosis;The scheme can save the detection branch selection unit, the high-voltage side ADC acquisition chip and the isolation chip, the circuit is simple, the occupied space is small, and the device cost is low.

[0089] Based on the above embodiment, the embodiment of the application also provides a battery management system, which comprises the relay sticking detection circuit provided by any of the above technical solutions. The relay sticking detection circuit and the battery management system provided by the embodiment of the application belong to the same inventive concept and can achieve the same technical effect, and repeated contents will not be described here.

[0090] The above specific embodiments do not constitute a limitation on the protection scope of the application. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent replacement and improvement within the spirit and principles of the application should be included in the protection scope of the application.

Claims

1. A relay sticking detection circuit characterized by comprising: The application relates to a vehicle relay sticking state detection device. The device comprises a first voltage division filter module, a second voltage division filter module, a hysteresis comparison module, an isolation module and a processing unit. The input end of the first voltage division filter module is connected with a vehicle battery pack, the first end and the second end of the first voltage division filter module are connected with the first end of a relay switch, and the output end of the first voltage division filter module is connected with the first input end of the hysteresis comparison module. The input end of the second voltage division filter module is connected with the vehicle battery pack, the first end and the second end of the second voltage division filter module are connected with the second end of the relay switch, the third end of the second voltage division filter module is connected with a ground signal, the output end of the second voltage division filter module is connected with the second input end of the hysteresis comparison module, and the first end of the hysteresis comparison module is connected with the first end of the relay switch. The input end of the isolation module is connected with the output end of the hysteresis comparison module, the first end of the isolation module is connected with a first power supply, the second end and the third end of the isolation module are connected with the ground signal, the output end of the isolation module is connected with the processing unit, and the processing unit is used for determining the sticking state of the relay switch according to the working state of the isolation module. The first voltage division filter module comprises a first voltage division unit, the first voltage division unit comprises a fourth resistor and a fifth resistor, the first end of the fourth resistor is used as the input end of the first voltage division filter module, the second end of the fourth resistor is connected with the first end of the fifth resistor, and the second end of the fifth resistor is used as the first end of the first voltage division filter module. The second voltage division filter module comprises a second voltage division unit, the second voltage division unit comprises a seventh resistor, an eighth resistor and a ninth resistor, the first end of the seventh resistor is used as the input end of the second voltage division filter module, the second end of the seventh resistor is connected with the first end of the eighth resistor and the first end of the ninth resistor, the second end of the eighth resistor is used as the first end of the second voltage division filter module, and the second end of the ninth resistor is used as the third end of the second voltage division filter module. The resistance value of the ninth resistor is much larger than that of the fifth resistor, and the resistance value of the eighth resistor is much smaller than that of the fifth resistor. The first input end of the hysteresis comparison module receives the output voltage of the first voltage division filter module, the second input end of the hysteresis comparison module receives the output voltage of the second voltage division filter module, the hysteresis comparison module is used for comparing the voltages of the first input end and the second input end, and according to the comparison result, a control signal is output to the isolation module, so as to indicate the sticking state of the relay switch through the working state of the isolation module.

2. The relay sticking detection circuit according to claim 1, characterized by, The hysteresis comparison module comprises a comparator, a first resistor and a first capacitor. The first input end of the comparator is used as the first input end of the hysteresis comparison module, the second input end of the comparator is used as the second input end of the hysteresis comparison module, and the output end of the comparator is used as the output end of the hysteresis comparison module. The first end of the first resistor is connected to the first input end of the comparator, the second end of the first resistor is connected to the output end of the comparator, the second end of the first resistor is connected to the first capacitor, and the second end of the first capacitor is the first end of the hysteresis comparison module.

3. The relay sticking detection circuit according to claim 1, characterized by, The isolation module includes an optical coupling isolation switch, a second resistor, and a third resistor. The first end of the second resistor is the input end of the isolation module, and the second end of the second resistor is connected to the first end of the optical coupling isolation switch. The second end and the third end of the optical coupling isolation switch are the second end and the third end of the isolation module, and the fourth end of the optical coupling isolation switch is the output end of the isolation module. The first end of the third resistor is connected to the fourth end of the optical coupling isolation switch, and the second end of the third resistor is the first end of the isolation module.

4. The relay sticking detection circuit according to claim 1, characterized by, The first voltage division filtering module further includes a first filter unit. The first end of the first filter unit is connected to the third end of the first voltage division unit, the second end of the first filter unit is the output end of the first voltage division filtering module, and the third end of the first filter unit is the second end of the first voltage division filtering module.

5. The relay sticking detection circuit according to claim 4, characterized by, The first filter unit includes a sixth resistor and a second capacitor. The first end of the sixth resistor is the first end of the first filter unit, and the second end of the sixth resistor is the second end of the first filter unit. The first end of the second capacitor is connected to the second end of the sixth resistor, and the second end of the second capacitor is the third end of the first filter unit.

6. The relay sticking detection circuit according to claim 1, characterized by, The second voltage division filtering module further includes a second filter unit. The first end of the second filter unit is connected to the third end of the second voltage division unit, the second end of the second filter unit is the output end of the second voltage division filtering module, and the third end of the second filter unit is the second end of the second voltage division filtering module.

7. The relay sticking detection circuit according to claim 6, characterized by, The second filter unit includes a tenth resistor and a third capacitor. The first end of the tenth resistor is the first end of the second filter unit, and the second end of the tenth resistor is the second end of the second filter unit. The first end of the third capacitor is connected to the second end of the tenth resistor, and the second end of the third capacitor is the third end of the second filter unit.

8. A battery management system, characterized by, The relay sticking detection circuit includes the relay sticking detection circuit according to any one of claims 1-7.

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