A high voltage circuit relay stick detection circuit and method

Abstract

The application discloses a high-voltage loop relay sticking detection circuit and method, wherein a first branch and a second branch are added to the high-voltage loop, the sticking of a pre-charging relay and a main positive relay can be accurately judged and distinguished, the whole circuit is simple in design, easy to realize, high in accuracy and low in cost, and thus more accurate sticking detection of the main positive relay and the pre-charging relay is realized on the basis of lower cost.

Description

Technical Field

[0001] This application relates to the field of electric vehicle technology, and more specifically, to a high-voltage circuit relay adhesion detection circuit and method. Background Technology

[0002] As a key component of electric vehicles, the power battery's first step in providing power output is energization. This involves first closing the main negative relay, then closing the pre-charge relay to connect the pre-charge resistor to the high-voltage circuit, and finally closing the main positive relay to safely connect the entire high-voltage circuit. Therefore, the proper functioning of the pre-charge relay and the main positive relay plays a crucial role in the entire energization process.

[0003] In existing technologies, voltage methods are generally used to detect adhesion in pre-charge relays and main positive relays. However, this method can only detect whether the main positive relay or the pre-charge relay is stuck, but it cannot distinguish whether the adhesion is in the main positive relay or the pre-charge relay. To clearly distinguish between the two, it is necessary to disassemble the relays to confirm their actual condition, which is labor-intensive, resource-intensive, and time-consuming. Alternatively, some companies use pre-charge relays with auxiliary contacts, which can clearly indicate when the pre-charge relay is stuck. However, these relays require special manufacturing and are often more expensive.

[0004] Therefore, how to achieve more accurate detection of adhesion between the main positive relay and the pre-charge relay at a lower cost is a technical problem that needs to be solved. Summary of the Invention

[0005] This invention provides a high-voltage circuit relay adhesion detection circuit and method to achieve more accurate adhesion detection of the main positive relay and the pre-charge relay at a lower cost.

[0006] In a first aspect, a high-voltage circuit relay adhesion detection circuit is provided, the circuit comprising:

[0007] The high-voltage circuit includes the power battery, main positive relay, pre-charge relay, pre-charge resistor, and main negative relay;

[0008] The first branch is in an on or off state, and is used to connect the load terminal of the main positive relay and the power supply terminal of the main negative relay when it is in the on state.

[0009] The second branch, which is in an on or off state, is used to introduce a preset voltage injection signal into the pre-charge resistor when it is in the on state.

[0010] The main positive relay is connected to the positive terminal of the power battery. The pre-charge relay and the pre-charge resistor are connected in series and then in parallel with the main positive relay. The first end of the first branch is connected to the load terminal of the main positive relay. The second end of the first branch and the power supply terminal of the main negative relay are connected to the negative terminal of the power battery. The first end of the second branch is connected between the pre-charge relay and the pre-charge resistor. The second end of the second branch is the input terminal of the preset voltage injection signal.

[0011] In some embodiments, the first branch includes a first switch and a first resistor connected in series, one end of the first switch being the first end of the first branch, the other end of the first switch being connected to one end of the first resistor, and the other end of the first resistor being the second end of the first branch.

[0012] In some embodiments, the resistance value of the first resistor is not less than three times the resistance value of the pre-charge resistor.

[0013] In some embodiments, the second branch includes a second switch, one end of which is a first end of the second branch, and the other end of which is a second end of the second branch.

[0014] In a second aspect, a method for detecting relay adhesion in a high-voltage circuit is provided, applied to the high-voltage relay adhesion detection circuit described in the first aspect, the method comprising:

[0015] In response to the adhesion detection command, the main positive relay, the pre-charge relay, the main negative relay, the first branch and the second branch are disconnected, and the first voltage at both ends of the first branch is obtained;

[0016] Based on the first voltage, determine whether at least one of the main positive relay and the precharge relay is stuck together;

[0017] If at least one of the main positive relay and the pre-charge relay sticks together, the first branch is closed, and a second voltage is obtained across the pre-charge resistor;

[0018] Based on the second voltage, determine whether the pre-charge relay is stuck and whether the main positive relay is not stuck;

[0019] If the pre-charge relay is not stuck and the main positive relay is not stuck, close the second branch and obtain the third voltage across the pre-charge resistor;

[0020] The third voltage indicates that the main positive relay is stuck and the pre-charge relay is not stuck, or that both the main positive relay and the pre-charge relay are stuck.

[0021] In some embodiments, the first branch includes a first switch and a first resistor connected in series. The step of determining whether the pre-charge relay is stuck and the main positive relay is not stuck based on the second voltage specifically involves:

[0022] If U t1 =E*Rpre / (Rpre+R1), then the precharge relay is stuck and the main positive relay is not stuck;

[0023] If U t1 If ≠E*Rpre / (Rpre+R1), then the precharge relay does not stick and the main positive relay does not stick.

[0024] Among them, U t1 The second voltage is E, the voltage of the power battery is E, Rpre is the resistance value of the pre-charge resistor, and R1 is the resistance value of the first resistor.

[0025] In some embodiments, the third voltage determines that the main positive relay is stuck and the pre-charge relay is not stuck, or that both the main positive relay and the pre-charge relay are stuck, specifically:

[0026] If the third voltage is equal to the preset voltage injection signal, then it is determined that the main positive relay is stuck and the precharge relay is not stuck.

[0027] If the third voltage is zero, it is determined that both the main positive relay and the precharge relay are stuck together.

[0028] In some embodiments, determining whether at least one of the main positive relay and the precharge relay is stuck together based on the first voltage specifically involves:

[0029] If the first voltage is not equal to zero and the difference between the voltage of the power battery and the first voltage is less than a preset difference, then it is determined that at least one of the main positive relay and the precharge relay is stuck together.

[0030] If the first voltage is equal to zero, it is determined that neither the main positive relay nor the precharge relay has stuck together.

[0031] By applying the above technical solutions, adding a first branch and a second branch to the high-voltage circuit, it is possible to accurately determine and distinguish whether the pre-charge relay and the main positive relay are stuck together. The entire circuit design is simple, easy to implement, highly accurate, and low in cost, thus achieving more accurate detection of sticking between the main positive relay and the pre-charge relay at a lower cost. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 A schematic diagram of a high-voltage circuit relay adhesion detection circuit according to an embodiment of the present invention is shown.

[0034] Figure 2 A flowchart illustrating a high-voltage circuit relay adhesion detection method proposed in an embodiment of the present invention is shown.

[0035] Figure 3 The equivalent circuit diagram after closing the first branch is shown in an embodiment of the present invention;

[0036] Figure 4 This invention illustrates the principle that, in an embodiment of the invention, the pre-charge relay sticks together after the first branch is closed, while the main positive relay does not stick together.

[0037] Figure 5 This invention illustrates the principle that, in an embodiment of the invention, the main positive relay sticks after the first branch is closed, while the pre-charge relay does not stick.

[0038] Figure 6 This diagram illustrates the principle that, in an embodiment of the present invention, the main positive relay and the precharge relay both stick together after the first branch is closed.

[0039] Figure 7 This invention illustrates the principle that, in an embodiment of the invention, after closing the first and second branches, the main positive relay becomes stuck together while the pre-charge relay does not.

[0040] Figure 8 This diagram illustrates the principle that, in an embodiment of the present invention, after the first and second branches are closed, both the main positive relay and the precharge relay become stuck together. Detailed Implementation

[0041] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0042] This application provides a high-voltage circuit relay adhesion detection circuit, such as... Figure 1 As shown, the circuit includes:

[0043] The high-voltage circuit includes the power battery E and the main positive relay S. pos Precharge relay S pre Pre-charge resistor R pre and main negative relay S neg ;

[0044] The first branch 10 is in an on or off state, and is used to connect the main positive relay S when it is in the on state. pos The load end and the main negative relay S neg The power supply terminal;

[0045] The second branch 20 is in an on or off state, and is used to introduce a preset voltage injection signal into the pre-charge resistor R when it is in the on state. pre ;

[0046] Among them, the main positive relay S pos The power supply terminal is connected to the positive terminal of the power battery E, and the pre-charge relay S pre and pre-charge resistor R pre After being connected in series with the main positive relay S pos In parallel, the first terminal of the first branch 10 is connected to the main positive relay S. pos The load end, the second terminal of the first branch 10 and the main negative relay S neg The power supply terminals are connected to the negative terminal of the power battery E, and the first terminal of the second branch 20 is connected to the pre-charge relay S. pre and pre-charge resistor R pre Between them, the second end of the second branch 20 is the input end of the preset voltage injection signal.

[0047] The steps for adhesion detection in the high-voltage circuit relay adhesion detection circuit of this application embodiment are as follows:

[0048] Step 1: Disconnect the main positive relay S pos Precharge relay S pre Main negative relay S neg First branch road 10 and second branch road 20.

[0049] Step 2, detect T link+ and T pack- If the voltage U1 between the two batteries is ≠ 0 and U1 is close to the power battery voltage E, then the main positive relay S is determined to be the positive relay. pos and precharge relay S pre At least one of them becomes stuck together, and step three is performed. If U1 = 0, then the main positive relay S pos and precharge relay S pre No adhesion was found; adhesion testing is now complete.

[0050] Step 3: Connect the first branch 10 and check the pre-charge resistor R. pre The second voltage across the terminals is U t1 At this time, the pre-charge resistor and the first branch 10 are connected in series. If U t1 For pre-charge resistor R pre The voltage drop across this series circuit determines the precharge relay S. pre Adhesion occurred and the main positive relay S pos No adhesion occurred. At this point, the specific adhesion situation has been identified, and the adhesion detection is complete; if U t1 Not the pre-charge resistor R pre The voltage drop across the series circuit, and U t1 If ≈0, then the precharge relay S is determined. pre No adhesion occurred and the main positive relay S pos Adhesion occurs, or the pre-charged relay S pre and main positive relay S pos All of them adhered together, proceed to step four.

[0051] Step 4: Connect the second branch 20 and input the preset voltage injection signal V. inj , if U t2 =V inj Then determine the precharge relay S pre No adhesion occurred and the main positive relay S pos Adhesion occurs, adhesion detection ends; if U t2 =0, then the precharge relay S is determined. pre and main positive relay S pos All adhesions occurred, and the adhesion test is now complete.

[0052] To ensure the reliability of the first branch, in some embodiments of this application, such as... Figure 1 As shown, the first branch 10 includes a first switch S1 and a first resistor R1 connected in series. One end of the first switch S1 is the first end of the first branch 10, and the other end of the first switch S1 is connected to one end of the first resistor R1. The other end of the first resistor R1 is the second end of the first branch 10.

[0053] To improve the safety of the power battery and high-voltage circuit, in some embodiments of this application, the resistance value of the first resistor R1 is not less than the pre-charge resistance R. pre Three times the resistance value.

[0054] To ensure the reliability of the second branch, in some embodiments of this application, such as... Figure 1 As shown, the second branch 20 includes a second switch S2, one end of which is the first end of the second branch 20, and the other end of which is the second end of the second branch S2.

[0055] By applying the above technical solutions, adding a first branch and a second branch to the high-voltage circuit, it is possible to accurately determine and distinguish whether the pre-charge relay and the main positive relay are stuck together. The entire circuit design is simple, easy to implement, highly accurate, and low in cost, solving the current difficulty in distinguishing between the sticking of the pre-charge relay and the sticking of the main positive relay.

[0056] This application also provides a method for detecting relay adhesion in a high-voltage circuit, applied in the high-voltage relay adhesion detection circuit described above. Figure 2 As shown, the method includes the following steps:

[0057] Step S101: In response to the adhesion detection command, disconnect the main positive relay, the pre-charge relay, the main negative relay, the first branch and the second branch, and obtain the first voltage at both ends of the first branch.

[0058] In this embodiment, the adhesion detection command can be user-inputted, automatically triggered before the high-voltage circuit is powered on, or triggered when other specified preset conditions are met. After detecting the adhesion detection command, the main positive relay, pre-charge relay, main negative relay, first branch, and second branch are disconnected, and then the first voltage across the first branch is obtained, such as... Figure 1 As shown, the first voltage is T. link+ and T pack- The voltage between them.

[0059] Step S102: Determine whether at least one of the main positive relay and the precharge relay is stuck together based on the first voltage.

[0060] In this embodiment, the magnitude of the first voltage can be used to determine whether at least one of the main positive relay and the pre-charge relay is stuck together. Specifically, the sticking together of at least one of the main positive relay and the pre-charge relay can be divided into three cases: (1) the main positive relay is stuck together and the pre-charge relay is not stuck together; (2) the pre-charge relay is stuck together and the main positive relay is not stuck together; (3) both the main positive relay and the pre-charge relay are stuck together.

[0061] To reliably determine whether at least one of the main positive relay and the pre-charge relay is stuck together, in some embodiments of this application, the determination of whether at least one of the main positive relay and the pre-charge relay is stuck together is based on the first voltage, specifically as follows:

[0062] If the first voltage is not equal to zero and the difference between the voltage of the power battery and the first voltage is less than a preset difference, then it is determined that at least one of the main positive relay and the precharge relay is stuck together.

[0063] If the first voltage is equal to zero, it is determined that neither the main positive relay nor the precharge relay has stuck together.

[0064] In this embodiment, as Figure 1 As shown, if the main positive relay S pos and precharge relay S pre If at least one of the components becomes stuck, the first voltage is not equal to zero and is close to the voltage of the power battery E. Therefore, if the first voltage is not equal to zero and the difference between the voltage of the power battery E and the first voltage is less than a preset difference, then the main positive relay S is determined to be stuck. pos and precharge relay S pre At least one of them is adhered, wherein the preset difference can be flexibly set according to actual needs by those skilled in the art.

[0065] If the main positive relay S pos and precharge relay S pre If no adhesion occurs, then the first voltage is zero. Therefore, if the first voltage is equal to zero, then the main positive relay S is determined. pos and precharge relay S pre No adhesion occurred.

[0066] Understandably, if it has been determined that neither the main positive relay nor the pre-charge relay has stuck together, then the sticking detection is considered complete.

[0067] Step S103: If at least one of the main positive relay and the pre-charge relay sticks together, close the first branch and obtain the second voltage across the pre-charge resistor.

[0068] In this embodiment, if at least one of the main positive relay and the pre-charge relay becomes stuck together, to further distinguish the specific sticking situation, it is necessary to close the first branch and then obtain the second voltage across the pre-charge resistor. In the specific application scenario of this application, such as... Figure 3 The diagram shown is the equivalent circuit after closing the first branch. After closing the first branch, the pre-charge resistor R... pre The second voltage across the terminals is U t1 .

[0069] Step S104: Determine whether the pre-charge relay is stuck and the main positive relay is not stuck based on the second voltage.

[0070] In this embodiment, based on the magnitude of the second voltage, it can be determined whether the pre-charge relay is stuck and the main positive relay is not stuck, thus determining two situations: (1) the pre-charge relay is stuck and the main positive relay is not stuck; (2) the main positive relay is stuck and the pre-charge relay is not stuck, or both the main positive relay and the pre-charge relay are stuck.

[0071] To reliably determine whether the pre-charge relay is stuck and the main positive relay is not stuck, in some embodiments of this application, the first branch includes a first switch and a first resistor connected in series. The determination of whether the pre-charge relay is stuck and the main positive relay is not stuck based on the second voltage specifically involves:

[0072] If U t1 =E*Rpre / (Rpre+R1), then the precharge relay is stuck and the main positive relay is not stuck;

[0073] If U t1 If ≠E*Rpre / (Rpre+R1), then the precharge relay does not stick and the main positive relay does not stick.

[0074] Among them, U t1 The second voltage is E, the voltage of the power battery is E, Rpre is the resistance value of the pre-charge resistor, and R1 is the resistance value of the first resistor.

[0075] In this embodiment, as Figure 1 As shown, the first branch 10 includes a first switch S1 and a first resistor R1 connected in series. One end of the first switch S1 is the first end of the first branch 10, and the other end of the first switch S1 is connected to one end of the first resistor R1. The other end of the first resistor R1 is the second end of the first branch 10. Optionally, the first resistor can also be replaced by multiple resistors connected in series.

[0076] like Figure 4 As shown, if U t1 =E*Rpre / (Rpre+R1), then there exists a precharge relay S. pre Adhesion occurred and the main positive relay S pos No adhesion occurred. At this point, the specific adhesion situation has been identified, and the adhesion detection is complete.

[0077] like Figure 5 As shown, if the main positive relay S pos If adhesion occurs but the precharge relay does not, then U t1 ≠E*Rpre / (Rpre+R1), and U t1 ≈0. For example... Figure 6 As shown, if the main positive relay S pos and precharge relay S pre If all of them adhere, then U t1 ≠E*Rpre / (Rpre+R1), and U t1 ≈0. Therefore, if U t1 If ≠E*Rpre / (Rpre+R1), then there is no sticking of the precharge relay and the main positive relay is not sticking.

[0078] Step S105: If the pre-charge relay is not stuck and the main positive relay is not stuck, close the second branch and obtain the third voltage across the pre-charge resistor.

[0079] In this embodiment, if the specific adhesion situation is still not distinguished after closing the first branch, the second branch needs to be closed, and a preset voltage injection signal is introduced from the second branch. The voltage across the pre-charge resistor changes from the second voltage to the third voltage, and the third voltage is obtained for further judgment.

[0080] Step S106: Determine, based on the third voltage, that the main positive relay is stuck and the pre-charge relay is not stuck, or that both the main positive relay and the pre-charge relay are stuck.

[0081] In this embodiment, it is necessary to further distinguish between case (1) where the main positive relay is stuck and the precharge relay is not stuck and case (2) where both the main positive relay and the precharge relay are stuck. Case (1) and case (2) can be determined based on the magnitude of the third voltage.

[0082] To reliably determine whether the main positive relay is stuck and the pre-charge relay is not stuck, or whether both the main positive relay and the pre-charge relay are stuck, in some embodiments of this application, the sticking of the main positive relay and the pre-charge relay are determined based on the third voltage, specifically as follows:

[0083] If the third voltage is equal to the preset voltage injection signal, then it is determined that the main positive relay is stuck and the precharge relay is not stuck.

[0084] If the third voltage is zero, it is determined that both the main positive relay and the precharge relay are stuck together.

[0085] In this embodiment, as Figure 7 As shown, the main positive relay S pos Adhesion occurred and the pre-charged relay S pre No adhesion occurred; at this time, the third voltage U t2 Equal to the preset voltage injection signal V inj Therefore, if the third voltage is equal to the preset voltage injection signal, it is determined that the main positive relay is stuck and the pre-charge relay is not stuck, and the sticking detection ends.

[0086] like Figure 8 As shown, the main positive relay S pos and precharge relay S pre All of them stick together. At this time, the third voltage U t2Since the third voltage is zero, it is determined that both the main positive relay and the precharge relay are stuck together.

[0087] By applying the above technical solutions, adding a first branch and a second branch to the high-voltage circuit, it is possible to accurately determine and distinguish whether the pre-charge relay and the main positive relay are stuck together. The entire circuit design is simple, easy to implement, highly accurate, and low in cost, solving the current difficulty in distinguishing between the sticking of the pre-charge relay and the sticking of the main positive relay.

[0088] To further illustrate the technical concept of this invention, the technical solution of this invention will now be described in conjunction with specific application scenarios.

[0089] This application provides a method for detecting relay adhesion in high-voltage circuits, applicable to, for example... Figure 1 In the high-voltage circuit relay adhesion detection circuit shown, the method includes the following steps:

[0090] Step 1: Disconnect the main positive relay S pos Precharge relay S pre Main negative relay S neg First switch S1 and second switch S2.

[0091] Step 2, detect T link+ and T pack- If the voltage U1 between the two batteries is ≠ 0 and U1 is close to the power battery voltage E, then the main positive relay S is determined to be the positive relay. pos and precharge relay S pre At least one of them becomes stuck together, and step three is performed. If U1 = 0, then the main positive relay S pos and precharge relay S pre No adhesion was found; adhesion testing is now complete.

[0092] Step 3, close the first switch S1, the equivalent circuit is as follows Figure 3 As shown. Detect the pre-charge resistance R. pre The second voltage across the terminals is U t1 , if U t1 =E*Rpre / (Rpre+R1), then the precharge relay S is determined. pre Adhesion occurred and the main positive relay S pos No adhesion occurred (e.g.) Figure 4 As shown), at this point, the specific adhesion situation has been identified, and the adhesion detection is complete; if U t1 ≠E*Rpre / (Rpre+R1), and U t1 If ≈0, then the precharge relay S is determined. pre No adhesion occurred and the main positive relay S pos Adhesion occurs (e.g.) Figure 5(as shown), or pre-charge relay S pre and main positive relay S pos All of them adhered (e.g.) Figure 6 (As shown), proceed to step four.

[0093] Step 4: Close the second switch S2 and input the preset voltage injection signal V. inj , if U t2 =V inj Then determine the precharge relay S pre No adhesion occurred and the main positive relay S pos Adhesion occurs (e.g.) Figure 7 (As shown), adhesion detection ends; if U t2 =0, then the precharge relay S is determined. pre and main positive relay S pos All of them adhered (e.g.) Figure 8 As shown in the image, the adhesion detection is complete.

[0094] In addition, the resistance value of resistor R1 can be selected based on the actual voltage of the power battery, and should not be less than the pre-charge resistance R. pre It has three times the resistance value to protect the power battery and high-voltage circuit.

[0095] This solution solves the difficulty of distinguishing between pre-charge relay adhesion and main positive relay adhesion by adding a small number of components. Compared with the prior art, the hardware circuit of this application embodiment has fewer modifications, is easier to implement, has clear logic judgment, low software requirements, low latency, high accuracy, and lower cost compared with other solutions.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A high-voltage circuit relay adhesion detection circuit, characterized in that, The circuit includes: The high-voltage circuit includes the power battery, main positive relay, pre-charge relay, pre-charge resistor, and main negative relay; The first branch is in an on or off state, and is used to connect the load terminal of the main positive relay and the power supply terminal of the main negative relay when it is in the on state; the first branch includes a first switch and a first resistor connected in series, one end of the first switch is the first end of the first branch, the other end of the first switch is connected to one end of the first resistor, and the other end of the first resistor is the second end of the first branch. The second branch, which is either in an on or off state, is used to introduce a preset voltage injection signal into the pre-charge resistor when it is in the on state; the resistance value of the first resistor is not less than three times the resistance value of the pre-charge resistor. The main positive relay is connected to the positive terminal of the power battery. The pre-charge relay and the pre-charge resistor are connected in series and then in parallel with the main positive relay. The first end of the first branch is connected to the load terminal of the main positive relay. The second end of the first branch and the power supply terminal of the main negative relay are connected to the negative terminal of the power battery. The first end of the second branch is connected between the pre-charge relay and the pre-charge resistor. The second end of the second branch is the input terminal of the preset voltage injection signal.

2. The circuit as described in claim 1, characterized in that, The second branch includes a second switch, one end of which is the first end of the second branch, and the other end of which is the second end of the second branch.

3. A method for detecting relay adhesion in a high-voltage circuit, characterized in that, Applied to the high-voltage circuit relay adhesion detection circuit as described in claim 1, the method includes: In response to the adhesion detection command, the main positive relay, the pre-charge relay, the main negative relay, the first branch and the second branch are disconnected, and the first voltage at both ends of the first branch is obtained; Based on the first voltage, determine whether at least one of the main positive relay and the precharge relay is stuck together; If at least one of the main positive relay and the pre-charge relay sticks together, the first branch is closed, and a second voltage is obtained across the pre-charge resistor; Based on the second voltage, determine whether the pre-charge relay is stuck and whether the main positive relay is not stuck; If the pre-charge relay is not stuck and the main positive relay is not stuck, close the second branch and obtain the third voltage across the pre-charge resistor; Based on the third voltage, it is determined that the main positive relay is stuck and the pre-charge relay is not stuck, or that both the main positive relay and the pre-charge relay are stuck. The first branch includes a first switch and a first resistor connected in series. The step of determining whether the pre-charge relay is stuck and whether the main positive relay is not stuck, based on the second voltage, specifically involves: If U t1 = E If Rpre / (Rpre+R1), then the precharge relay is stuck together while the main positive relay is not stuck together. If U t1 ≠E If Rpre / (Rpre+R1), then the precharge relay does not stick and the main positive relay does not stick; Among them, U t1 The second voltage is E, the voltage of the power battery is E, Rpre is the resistance value of the pre-charge resistor, and R1 is the resistance value of the first resistor.

4. The method as described in claim 3, characterized in that, Based on the third voltage, it is determined that the main positive relay is stuck and the pre-charge relay is not stuck, or that both the main positive relay and the pre-charge relay are stuck, specifically: If the third voltage is equal to the preset voltage injection signal, then it is determined that the main positive relay is stuck and the precharge relay is not stuck. If the third voltage is zero, it is determined that both the main positive relay and the precharge relay are stuck together.

5. The method as described in claim 3, characterized in that, Based on the first voltage, it is determined whether at least one of the main positive relay and the pre-charge relay is stuck together. Specifically: If the first voltage is not equal to zero and the difference between the voltage of the power battery and the first voltage is less than a preset difference, then it is determined that at least one of the main positive relay and the precharge relay is stuck together. If the first voltage is equal to zero, it is determined that neither the main positive relay nor the precharge relay has stuck together.

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