Relay adhesion detection circuit and method

Abstract

The invention discloses a relay adhesion detection circuit and method. The relay adhesion detection circuit comprises a positive relay and a negative relay which are coupled between a battery and a load, the pre-charging relay and the pre-charging resistor are connected in series and are coupled between the positive electrode of the battery and a load; the detection circuit is provided with a first end, a second end and a third end, the first end is coupled between the anode relay and the load, the second end is coupled between the cathode relay and the load, the third end is coupled to the cathode of the battery, a path from the first end to the third end is provided with a first detection point, and a path from the second end to the third end is provided with a second detection point; the sampling unit is provided with a first sampling end, a second sampling end and a third sampling end, the first sampling end is coupled to the first detection point to read the voltage of the first detection point, the second sampling end is coupled to the second detection point to read the voltage of the second detection point, and the third sampling end is coupled to the negative electrode of the battery to read the voltage of the negative electrode of the battery; dynamic upper and lower high-voltage process detection and static detection are both considered, and positive and negative relays can be detected at the same time.

Description

Technical Field

[0001] The present application relates to the field of relays, and in particular to a relay adhesion detection circuit and method. Background Art

[0002] At present, the new energy industry is developing rapidly, and the safety and efficiency of BMS (Battery Management System) have always been the concern of many manufacturers. BMS controls the on / off and closing of the high-voltage circuit through relays. When the relays are used for a long time, there are problems such as poor contact and material aging. Or under abnormal conditions such as frequent switching under load, over-temperature and over-current, the negative relay contacts may not be completely separated, resulting in short circuit or overload, and may even cause safety accidents such as electric shock and fire. Therefore, in order to ensure the safety of the high-voltage circuit, it is necessary to accurately detect the adhesion of the battery negative relay.

[0003] At present, the relay adhesion detection circuit generally includes positive relays, pre-charge relays and negative relays, etc. The BMS collects the voltage of the negative relay contact before and after the high voltage is powered on to determine whether there is a contact adhesion fault. Some battery packs have high voltages, the discharge circuit is damaged, or the power is turned on and off continuously, which will cause the relay adhesion detection to be low in accuracy and poor in safety. One existing solution is to connect a Hall sensor or a shunt resistor in series with the negative relay or switch contact to determine whether the current meets expectations. This solution has a high device cost. Another solution is to connect a comparator or other logic circuit at both ends of the negative relay or switch contact, and use the above logic circuit to determine the state of the negative relay contact. This solution also has a high device cost and a single application scenario, and cannot detect adhesion faults during the high voltage and low voltage processes. Therefore, there is an urgent need for a relay adhesion detection solution with a lower cost and more comprehensive detection methods. Summary of the invention

[0004] The embodiments of the present application provide a relay adhesion detection circuit and method to reduce the cost of the relay adhesion detection circuit and improve the relay adhesion detection method.

[0005] In order to solve the above technical problems, the embodiments of the present application disclose the following technical solutions:

[0006] On the one hand, a relay adhesion detection circuit is provided, comprising: a positive relay coupled between a positive electrode of a battery and a load; a negative relay coupled between a negative electrode of the battery and a load; a pre-charge relay and a pre-charge resistor, wherein the pre-charge relay and the pre-charge resistor are connected in series and coupled between the positive electrode of the battery and the load; a detection circuit having a first end, a second end and a third end, wherein the first end is coupled between the positive electrode relay and the load, the second end is coupled between the negative electrode relay and the load, the third end is coupled to the negative electrode of the battery, the path from the first end to the third end has a first detection point, and the path from the second end to the third end has a second detection point; a sampling unit having a first sampling end, a second sampling end and a third sampling end, wherein the first sampling end is coupled to the first detection point, the second sampling end is coupled to the second detection point, and the third sampling end is coupled to the negative electrode of the battery, and the sampling unit reads the voltage of the first detection point through the first sampling end, reads the voltage of the second detection point through the second sampling end, and reads the voltage of the negative electrode of the battery through the third sampling end.

[0007] Furthermore, the sampling unit also has a first output terminal, the first output terminal outputs a first reference voltage, and a first reference voltage dividing resistor is coupled between the first output terminal and the second detection point.

[0008] Furthermore, the detection circuit also includes a first voltage-dividing resistor and a first detection resistor, one end of the first voltage-dividing resistor is the first end of the detection circuit, and the other end is the first detection point, and the two ends of the first detection resistor are respectively coupled to the first detection point and the negative electrode of the battery.

[0009] Furthermore, the detection circuit also includes a second voltage-dividing resistor and a second detection resistor, one end of the second voltage-dividing resistor is the second end of the detection circuit, and the other end is the second detection point, and the two ends of the second detection resistor are respectively coupled to the second detection point and the negative electrode of the battery.

[0010] Furthermore, the sampling unit also has a second output terminal and a third output terminal, the second output terminal outputs a second reference voltage, and the third output terminal outputs a control signal; a protection switch is coupled between the second detection resistor and the negative electrode of the battery, and the protection switch is controlled by the control signal output by the sampling unit; a transistor and a diode are coupled between the second sampling terminal and the third sampling terminal, the base of the transistor is coupled to the second output terminal, and the overcurrent of the sampling unit is introduced from the second sampling terminal to the negative electrode of the battery, the positive electrode of the diode is coupled to the third sampling terminal, and the negative electrode is coupled to the second sampling terminal.

[0011] In each of the above relay adhesion detection circuits, the load has an equivalent high-voltage resistor and an equivalent high-voltage capacitor, and the equivalent high-voltage resistor and the equivalent high-voltage capacitor are coupled in parallel.

[0012] On the other hand, a relay adhesion detection method is also provided, which is applied to the relay adhesion detection circuit as described in any of the above technical solutions, and the detection method at least includes: the sampling unit samples the voltages of the first detection point, the second detection point and the negative electrode of the battery; the sampling unit calculates the outer side voltages of the positive relay and the negative relay according to the voltages of the first detection point, the second detection point and the negative electrode of the battery; upper high voltage process detection: the sampling unit determines whether a adhesion fault occurs according to the outer side voltages of the positive relay and the negative relay; lower high voltage process detection: the sampling unit determines whether a adhesion fault occurs according to the changing trend of the outer side voltages of the positive relay and the negative relay; wherein the outer side of the positive relay is the side where the positive relay is coupled to the load, and the outer side of the negative relay is the side where the negative relay is coupled to the load.

[0013] Furthermore, the above method also includes: static detection: the sampling unit sets a preset value according to the first reference voltage and the parameters of the detection circuit; the sampling unit determines whether a adhesion fault occurs according to the difference between the voltage of the second detection point and the preset value.

[0014] Furthermore, the upper high-voltage process detection includes: if the outer voltage of the positive pole relay is close to or equal to the positive pole voltage of the battery, it is judged that the positive pole relay has a adhesion fault; otherwise, the pre-charge relay is closed; if the outer voltage of the negative pole relay is close to or equal to zero, it is judged that the negative pole relay has a adhesion fault; otherwise, the negative pole relay is closed; the lower high-voltage process detection includes: if the outer voltage of the negative pole relay is zero, and the outer voltage of the positive pole relay gradually decreases, it is judged that the negative pole relay has a adhesion fault; if the outer voltage of the negative pole relay is greater than zero and gradually increases, it is judged that the positive pole relay has a adhesion fault; if the outer voltage of the positive pole relay is the positive pole voltage of the battery, and the outer voltage of the negative pole relay is zero, it is judged that both the positive pole relay and the negative pole relay have adhesion faults.

[0015] Furthermore, the preset value includes a first preset value and a second preset value, and the sampling unit judges whether a sticking fault occurs based on the difference between the voltage of the second detection point and the preset value, including: if the voltage of the second detection point is less than the voltage of the first preset value, it is judged that the negative pole relay is disconnected; if the voltage of the second detection point is less than the voltage of the second preset value, it is judged that a sticking fault occurs in the negative pole relay; wherein, the first preset value is the voltage of the second detection point when the negative pole relay is normally disconnected, and the first preset value is the voltage of the second detection point when the negative pole relay is normally closed.

[0016] The above-mentioned technical solutions have at least the following advantages or beneficial effects: the relay adhesion detection circuit connects the detection circuit through the outer end points of the positive pole relay and the negative pole relay, which is safer than the detection circuit that performs detection at both ends of the relay in the prior art; the relay adhesion detection method is combined with the detection circuit, which can be compatible with dynamic detection and static detection, and can simultaneously detect adhesion faults of both the positive pole relay and the negative pole relay. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The technical solutions and other beneficial effects of the present invention will be made apparent by describing in detail the specific embodiments of the present invention in conjunction with the accompanying drawings.

[0018] Figure 1 It is a module block diagram of the first embodiment;

[0019] Figure 2 is a circuit diagram of Embodiment 2;

[0020] Figure 3 This is a circuit diagram of Example 3. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and beneficial effects of this application clearer, the following further describes this application in detail in conjunction with the accompanying drawings and specific implementation methods. It should be understood that the specific implementation methods described in this specification are only for explaining the present invention, and are not intended to limit this application.

[0022] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" refers to two or more, unless otherwise clearly and specifically defined.

[0023] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0025] During the process of high voltage on new energy vehicles, the positive relay, negative relay and pre-charge relay work together in a certain sequence to ensure safe and stable access to the high voltage system. Applying high voltage is the process of switching from a power-off state to a working state. Generally, the positive relay controls the connection between the positive pole of the high-voltage battery and the high-voltage bus, and the negative relay controls the connection between the negative pole of the high-voltage battery and the high-voltage bus. The pre-charge relay gradually increases the voltage of the high-voltage bus through the pre-charge resistor to avoid instantaneous large current shocks. When the high voltage is reduced, the negative relay is generally disconnected first to cut off the connection between the negative pole of the high-voltage battery and the high-voltage bus to reduce the risk of arcing and contact erosion. In the process of lowering the high voltage, after disconnecting the positive relay, the BMS generally detects the voltage of the high-voltage bus through a voltage sensor. If the high-voltage bus voltage does not drop to the expected value after the main circuit is disconnected, the BMS will determine whether the relay is sticking or malfunctioning. If the high-voltage bus voltage has not completely dropped to a safe value, the pre-charge relay is closed and the discharge circuit (usually a high-power resistor) is connected to quickly consume the residual charge in energy storage devices such as capacitors to reduce the high-voltage bus voltage to a safe range. When the high-voltage bus voltage drops to a safe value, the pre-charge relay is disconnected, all high-voltage relays are in a disconnected state, and the high-voltage battery is completely isolated from the load.

[0026] Embodiment 1 provided in the present application can detect adhesion faults of the positive pole relay and the negative pole relay by judging the voltage outside the relay during the above-mentioned upper high voltage process and lower high voltage process.

[0027] Figure 1 is a module block diagram of the first embodiment, such as Figure 1 As shown, the relay adhesion detection circuit includes a positive relay K1 coupled between the positive electrode of the battery 3 and the load 4, and a negative relay K3 coupled between the negative electrode of the battery 3 and the load 4; the pre-charge relay K2 and the pre-charge resistor R1 are connected in series and coupled between the positive electrode of the battery 3 and the load 4; the detection circuit 1 has a first end, a second end and a third end, wherein the first end is coupled between the positive relay K1 and the load 4, the second end is coupled between the negative relay K3 and the load 4, and the third end is coupled to the negative electrode of the battery 3, and the path from the first end to the third end has a first detection point A, and the path from the second end to the third end has a second detection point B; the sampling unit 2 has a first sampling end, a second sampling end and a third sampling end, wherein the first sampling end is coupled to the first detection point A, the second sampling end is coupled to the second detection point B, and the third sampling end is coupled to the negative electrode of the battery, and the sampling unit 2 reads the voltage of the first detection point A through the first sampling end, reads the voltage of the second detection point B through the second sampling end, and reads the voltage of the negative electrode of the battery through the third sampling end. In this embodiment, the load 4 has an equivalent high-voltage resistor R and an equivalent high-voltage capacitor connected in parallel. In the description of the process of increasing and decreasing the high voltage of the above-mentioned new energy vehicle, in this embodiment, during the process of increasing the high voltage, the pre-charge relay K2 is closed first, and the positive relay K1 and the negative relay K2 are closed in sequence. When the load works normally, the pre-charge relay K2 is disconnected. During the process of decreasing the high voltage, the negative relay K3 is disconnected first and then the positive relay K1. In addition, in the embodiment of the present application, the outer sides of the positive relay K1 and the negative relay K3 are each coupled to one end of the load, wherein the outer side of the positive relay K1 is marked as D, and the outer side of the negative relay K3 is marked as C, the voltage of the positive pole of the battery 3 is Battery+, and the voltage of the negative pole is Battery-.

[0028] Figure 2 Schematic diagram of the circuit of the second embodiment. Figure 2 As shown, in this embodiment, based on the first embodiment, the sampling unit 2 further has a first output terminal, the first output terminal outputs a first reference voltage VREF1, and a first reference voltage dividing resistor R13 is coupled between the first output terminal and the second detection point B. The detection circuit 1 also includes a first dividing resistor R11 and a first detection resistor R21 and a second dividing resistor R12 and a second detection resistor R22, one end of the first dividing resistor R11 is the first end of the detection circuit 1, and the other end is the first detection point A, and the two ends of the first detection resistor R21 are respectively coupled to the first detection point A and the negative electrode of the battery 3; one end of the second dividing resistor R12 is the second end of the detection circuit 1, and the other end is the second detection point B, and the two ends of the second detection resistor R22 are respectively coupled to the second detection point B and the negative electrode of the battery 3.

[0029] Figure 3 Schematic diagram of the circuit of the third embodiment. Figure 3 As shown, in this embodiment, on the basis of the second embodiment, the sampling unit 2 further has a second output terminal and a third output terminal, the second output terminal outputs a second reference voltage VREF2, and the third output terminal outputs a control signal Ctrl; a protection switch S1 is coupled between the second voltage-dividing resistor R12 and the negative electrode of the battery 3, and the protection switch S1 is controlled by the control signal Ctrl output by the sampling unit 2; a transistor and a diode are coupled between the second sampling terminal and the third sampling terminal, the base of the transistor is coupled to the second output terminal, and the overcurrent of the sampling unit 2 is introduced from the second sampling terminal to the negative electrode of the battery 3, the positive electrode of the diode is coupled to the third sampling terminal, and the negative electrode is coupled to the second sampling terminal; wherein, the overcurrent is a high current generated by the voltage or overvoltage of the battery 3 when the negative electrode relay K3 is not adhered but the positive electrode relay K1 is adhered during the low-voltage process.

[0030] The relay adhesion detection method provided in the embodiment of the present application at least includes: the sampling unit 2 samples the voltages of the first detection point A, the second detection point B and the negative electrode of the battery 3; the sampling unit 2 calculates the outer voltages of the positive relay K1 and the negative relay K3 according to the voltages of the first detection point A, the second detection point B and the negative electrode of the battery 3; upper high-voltage process detection: the sampling unit 2 determines whether an adhesion fault occurs according to the outer voltages of the positive relay K1 and the negative relay K3; lower high-voltage process detection: the sampling unit 2 determines whether an adhesion fault occurs according to the changing trend of the outer voltages of the positive relay K1 and the negative relay K3.

[0031] Taking the second or third embodiment as an example, during the high voltage application process, after the sampling unit 2 collects the voltage of the first detection point A and the voltage Battery- of the negative electrode of the battery 3, the voltage of the outer point D of the positive relay K1 can be calculated by the voltage dividing ratio of the first voltage dividing resistor R11 and the first detection resistor R21 according to the parameters of the first voltage dividing resistor R11 and the first detection resistor R21; if the positive relay K1 has no adhesion fault, the pre-charge relay K2 is closed, and after the sampling unit 2 collects the voltage of the second detection point B and the voltage Battery- of the negative electrode of the battery 3, the voltage of the outer point C of the negative relay K3 can be calculated. If the negative relay K3 is normal and has no adhesion fault, the voltage of point C VC=VB / (R12 / R22+R13), wherein VB is the voltage of the second detection point B collected by the sampling unit 2, and the voltage of point C is calculated by the second detection resistor R22 and the first reference voltage dividing resistor R13. If the voltage of point C is close to 0V, it is determined that the negative relay K3 has a contact adhesion fault. During the high voltage process, the negative relay K3 is disconnected first. If both the positive relay K1 and the negative relay K3 have no adhesion fault, the equivalent high voltage capacitor forms a loop with the first voltage-dividing resistor R11, the sampling unit 2, and the second voltage-dividing resistor R12. The potential at point C is lower than the negative voltage of the battery 3 and is a negative value. Therefore, the sampling unit 2 can judge the adhesion fault according to the value of the voltage at point C; specifically, it includes: if the outer voltage of the negative relay K3 is zero, and the outer voltage of the positive relay K1 gradually decreases, it is judged that the negative relay K3 has an adhesion fault; if the outer voltage of the negative relay K3 is greater than zero and gradually increases, it is judged that the positive relay K1 has an adhesion fault; if the outer voltage of the positive relay K1 is the positive voltage of the battery 3, and the outer voltage of the negative relay K3 is zero, it is judged that both the positive relay K1 and the negative relay K3 have adhesion faults.

[0032] The relay adhesion detection method provided in the embodiment of the present application also includes static detection, and the static detection is that the sampling unit 2 sets a preset value according to the first reference voltage VREF1 and the parameters of the detection circuit 1; the sampling unit 2 determines whether an adhesion fault occurs according to the difference between the voltage of the second detection point B and the preset value. The preset value includes a first preset value and a second preset value, and the sampling unit 2 determines whether an adhesion fault occurs according to the difference between the voltage of the second detection point B and the preset value, including: if the voltage of the second detection point B is less than the voltage of the first preset value, it is determined that the negative relay K3 is disconnected; if the voltage of the second detection point B is less than the voltage of the second preset value, it is determined that the negative relay K3 has an adhesion fault; wherein, the first preset value is the voltage of the second detection point B when the negative relay K3 is normally disconnected, and the first preset value is the voltage of the second detection point B when the negative relay K3 is normally closed. Taking the second embodiment or the third embodiment as an example, the first preset value and the second preset value are explained as follows: the static detection includes two circuit states before the upper high voltage and after the lower high voltage. When the negative electrode relay K3 is disconnected, the second detection resistor R22, the first voltage-dividing resistor R11 and the first detection resistor R21 are connected to the negative electrode of the battery 3, that is, the series circuit of the second detection resistor R22, the equivalent high-voltage resistor R, the first voltage-dividing resistor R11 and the first detection resistor R21 is connected in parallel with the second voltage-dividing resistor R12, and the first reference voltage VR The EF1 voltage-dividing resistors jointly divide the first reference voltage VREF1, and the first preset value is set to VREF1*(R12 / / (R22+R+R11+R21)) / (R13+R12 / / (R22+R+R11+R21)); when the negative pole relay K3 is closed, the second voltage-dividing resistor R12 is connected in parallel with the second detection resistor R22, and the second preset value is set to Battery+*(R12 / / R22) / (R13+R12 / / R22).

[0033] The introduction provided in the above steps is only used to help understand the method, structure and core idea of ​​the present invention. For ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also belong to the scope of protection of the claims of the present invention.

Claims

1. A relay adhesion detection circuit, characterized in that: include: A positive relay coupled between the positive terminal of the battery and the load; A negative relay coupled between the negative terminal of the battery and the load; A pre-charging relay and a pre-charging resistor, wherein the pre-charging relay and the pre-charging resistor are connected in series and coupled between the positive electrode of the battery and the load; A detection circuit having a first end, a second end and a third end, wherein the first end is coupled between the positive relay and the load, the second end is coupled between the negative relay and the load, the third end is coupled to the negative electrode of the battery, a path from the first end to the third end has a first detection point, and a path from the second end to the third end has a second detection point; The sampling unit has a first sampling terminal, a second sampling terminal and a third sampling terminal, wherein the first sampling terminal is coupled to the first detection point, the second sampling terminal is coupled to the second detection point, and the third sampling terminal is coupled to the negative electrode of the battery. The sampling unit reads the voltage of the first detection point through the first sampling terminal, reads the voltage of the second detection point through the second sampling terminal, and reads the voltage of the negative electrode of the battery through the third sampling terminal.

2. The relay adhesion detection circuit according to claim 1, characterized in that: The sampling unit also has a first output terminal. The first output terminal outputs a first reference voltage, and a first reference voltage dividing resistor is coupled between the first output terminal and the second detection point.

3. The relay adhesion detection circuit according to claim 1, characterized in that: The detection circuit also includes a first voltage-dividing resistor and a first detection resistor, one end of the first voltage-dividing resistor is the first end of the detection circuit, and the other end is the first detection point, and the two ends of the first detection resistor are respectively coupled to the first detection point and the negative electrode of the battery.

4. The relay adhesion detection circuit according to claim 1, characterized in that: The detection circuit also includes a second voltage-dividing resistor and a second detection resistor, one end of the second voltage-dividing resistor is the second end of the detection circuit, and the other end is the second detection point, and the two ends of the second detection resistor are respectively coupled to the second detection point and the negative electrode of the battery.

5. The relay adhesion detection circuit according to claim 4, characterized in that: The sampling unit further has a second output terminal and a third output terminal, the second output terminal outputs a second reference voltage, and the third output terminal outputs a control signal; A protection switch is coupled between the second detection resistor and the negative electrode of the battery, and the protection switch is controlled by a control signal output by the sampling unit; A transistor and a diode are coupled between the second sampling terminal and the third sampling terminal. The base of the transistor is coupled to the second output terminal and guides the overcurrent of the sampling unit from the second sampling terminal to the negative electrode of the battery. The anode of the diode is coupled to the third sampling terminal, and the cathode is coupled to the second sampling terminal.

6. The relay adhesion detection circuit according to claim 1, characterized in that: The load has an equivalent high-voltage resistor and an equivalent high-voltage capacitor, and the equivalent high-voltage resistor and the equivalent high-voltage capacitor are coupled in parallel.

7. A relay adhesion detection method, characterized in that: The relay adhesion detection circuit as claimed in any one of claims 1 to 6 comprises: The sampling unit samples the voltages of the first detection point, the second detection point and the negative electrode of the battery; The sampling unit calculates the outer voltage of the positive relay and the negative relay according to the voltage of the first detection point, the second detection point and the negative electrode of the battery; High voltage process detection: the sampling unit determines whether a sticking fault occurs according to the outer voltages of the positive relay and the negative relay; Lower high voltage process detection: the sampling unit determines whether a sticking fault occurs according to the change trend of the outer voltage of the positive relay and the negative relay; The outer side of the positive relay is the side where the positive relay is coupled to the load, and the outer side of the negative relay is the side where the negative relay is coupled to the load.

8. The relay adhesion detection method according to claim 7, characterized in that: Also includes: Static detection: the sampling unit sets a preset value according to the first reference voltage and the parameters of the detection circuit; The sampling unit determines whether a sticking fault occurs according to a difference between the voltage at the second detection point and the preset value.

9. The relay adhesion detection method according to claim 7, characterized in that: The upper high pressure process detection includes: If the outer voltage of the positive relay is close to or equal to the positive voltage of the battery, it is determined that the positive relay has a sticking fault; otherwise, the pre-charge relay is closed; If the outer voltage of the negative electrode relay is close to or equal to zero, it is determined that the negative electrode relay has a sticking fault; otherwise, the negative electrode relay is closed; The lower high pressure process detection includes: If the outer voltage of the negative relay is zero and the outer voltage of the positive relay gradually decreases, it is determined that a sticking fault occurs in the negative relay; If the outer voltage of the negative relay is greater than zero and gradually increases, it is determined that the positive relay has a sticking fault; If the outer voltage of the positive relay is the positive voltage of the battery, and the outer voltage of the negative relay is zero, it is determined that both the positive relay and the negative relay have adhesion failures.

10. The relay adhesion detection method according to claim 8, characterized in that: The preset value includes a first preset value and a second preset value, The sampling unit determines whether a sticking fault occurs according to the difference between the voltage at the second detection point and the preset value, including: If the voltage at the second detection point is less than the voltage at the first preset value, it is determined that the negative relay is disconnected; If the voltage at the second detection point is less than the voltage of the second preset value, it is determined that a sticking fault occurs to the negative relay; Among them, the first preset value is the voltage of the second detection point when the negative pole relay is normally disconnected, and the first preset value is the voltage of the second detection point when the negative pole relay is normally closed.

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