Relay state detection circuit, detection method, and battery management system

Abstract

A relay state detection circuit, a detection method, and a battery management system. The circuit comprises a power battery pack (1), a plurality of relays (2), a voltage collector (3), a plurality of voltage division circuits (4), and a controller (5); the plurality of relays (2) are sequentially connected in series between a positive electrode and a negative electrode of the power battery pack (1); two ends of each relay (2) are each provided with a detection point; and the controller (5) is electrically connected to the voltage collector (3), and is configured to: receive voltage values of first voltage ends (401) of the voltage division circuits (4) collected by the voltage collector (3), obtain voltage values of the detection points at the two ends of a relay under detection on the basis of the voltage values of the first voltage ends (401) of the voltage division circuits (4) connected to the detection points at the two ends of the relay under detection and voltage values of reference voltage ends (UVREF), and determine the state of the relay under detection on the basis of the voltage values of the detection points at the two ends of the relay under detection. At least one of the detection points at the two ends of the relay under detection is in a power-on state.

Description

Relay status detection circuit and detection method, battery management system

[0001] This application claims priority to Chinese patent application No. 202410829937.3, filed on June 25, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates to the field of battery management system technology, and in particular to a relay state detection circuit and detection method, and a battery management system. Background Technology

[0003] With the iteration and upgrading of new energy technologies, the development of electric vehicles is becoming increasingly mature and their applications are becoming more widespread. For example, passenger cars, logistics vehicles, communication vehicles, and special vehicles are gradually adopting power batteries as the main power supply system. Correspondingly, the safety requirements for power batteries are becoming increasingly stringent. As the control unit for the energy output of the power battery, the Battery Management System (BMS) needs to monitor the working status of the high-voltage relays and related high-voltage devices of the power battery. Summary of the Invention

[0004] This disclosure provides a relay status detection circuit and detection method, a battery management system, and a relay status detection circuit voltage acquisition unit and multiple voltage divider circuits to detect the opening and closing of the relay in real time, thereby reducing costs.

[0005] In a first aspect, a relay state detection circuit is provided. The relay state detection circuit includes: a power battery pack, multiple relays, a voltage acquisition unit, multiple voltage divider circuits, and a controller; the multiple relays are connected in series between the positive and negative terminals of the power battery pack; each of the multiple relays has a detection point at both ends; the first voltage terminal of each of the multiple voltage divider circuits is electrically connected to the voltage acquisition terminal of the voltage acquisition unit; the second voltage terminal of the voltage divider circuit is electrically connected to a detection point, and the third voltage terminal of the voltage divider circuit is electrically connected to a reference voltage terminal; the voltage acquisition unit is configured to acquire the voltage value of the first voltage terminal of the voltage divider circuit.

[0006] The controller is electrically connected to the voltage acquisition unit. The controller is configured to: receive the voltage value at the first voltage terminal of the voltage divider circuit acquired by the voltage acquisition unit; and, based on the voltage values ​​at the first voltage terminal of the voltage divider circuit connected to the detection points at both ends of the relay under test and the voltage value at the reference voltage terminal, obtain the voltage values ​​at the detection points at both ends of the relay under test; and determine the state of the relay under test based on the voltage values ​​at the detection points at both ends of the relay under test. The state of the relay under test includes the relay under test being open and the relay under test being closed. The relay under test is one of multiple relays, and at least one of the detection points at both ends of the relay under test is in an energized state.

[0007] Secondly, a detection method for a relay status detection circuit is provided. This detection method is applied to the aforementioned relay status detection circuit.

[0008] The method includes: receiving the voltage value of the first voltage terminal of the voltage divider circuit acquired by a voltage acquisition device; obtaining the voltage values ​​of the detection points at both ends of the relay under test based on the voltage values ​​of the first voltage terminal of the voltage divider circuit connected to the detection points at both ends of the relay under test and the voltage value of the reference voltage terminal; and determining the state of the relay under test based on the voltage values ​​of the detection points at both ends of the relay under test. The state of the relay under test includes the relay under test being open and the relay under test being closed. The relay under test is one of multiple relays, and at least one of the detection points at both ends of the relay under test is in an energized state.

[0009] Thirdly, a battery management system is provided. This battery management system includes the aforementioned relay state detection circuit. Attached Figure Description

[0010] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure, and are not intended to unduly limit this disclosure.

[0011] Figure 1 is a schematic diagram of a relay state detection circuit in the related art;

[0012] Figure 2 is a block diagram of a relay state detection circuit according to some embodiments;

[0013] Figure 3 is a circuit diagram of a relay state detection circuit according to some embodiments;

[0014] Figure 4 is a circuit diagram of another relay state detection circuit according to some embodiments;

[0015] Figure 5 is a circuit diagram of another relay state detection circuit according to some embodiments;

[0016] Figure 6 is a circuit diagram of another relay state detection circuit according to some embodiments;

[0017] Figure 7 is a circuit diagram of yet another relay state detection circuit according to some embodiments;

[0018] Figure 8 is a flowchart of a method for detecting multiple voltage divider circuits according to some embodiments;

[0019] Figure 9 is a circuit diagram of another relay state detection circuit according to some embodiments;

[0020] Figure 10 is a circuit diagram of yet another relay state detection circuit according to some embodiments;

[0021] Figure 11 is a flowchart of a relay state detection circuit detection method according to some embodiments;

[0022] Figure 12 is a flowchart of a first relay state detection circuit detection method according to some embodiments;

[0023] Figure 13 is a flowchart of a second relay state detection circuit detection method according to some embodiments;

[0024] Figure 14 is a flowchart of a third relay state detection circuit detection method according to some embodiments;

[0025] Figure 15 is a flowchart of a fourth relay state detection circuit detection method according to some embodiments;

[0026] Figure 16 is a flowchart of a fifth relay state detection circuit detection method according to some embodiments;

[0027] Figure 17 is a block diagram of a battery management control system according to some embodiments. Detailed Implementation

[0028] To enable those skilled in the art to better understand the technical solutions of this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings.

[0029] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this disclosure 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 this disclosure described herein can be implemented in orders other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this disclosure as detailed in the appended claims.

[0030] Currently, in the high-voltage relay circuit of a power battery, the battery management system cannot determine which specific high-voltage relay is malfunctioning, leading to problems such as failure to complete high-voltage power-on or damage to the battery pack, or completing the high-voltage power-on process but failing to identify the current status of the high-voltage relay. These malfunctions of high-voltage relays and devices introduce safety risks into vehicle use and maintenance.

[0031] For example, relay status detection circuits in related technologies can diagnose the fault conditions of relays and devices, ensuring that the power battery pack completes the high-voltage power-on process when all relays and devices are functioning normally. However, while detecting relay sticking, it is necessary to prioritize closing the corresponding relay that can form a loop, which still carries the risk of abnormal high voltage application. Furthermore, the voltage acquisition circuit used in complex high-voltage topologies significantly reduces the insulation resistance of the circuit loop and can lead to unpredictable potentials between originally separated test points, introducing other problems and reducing system safety. Here, relay sticking refers to the phenomenon where relay contacts stick together and cannot be properly separated during switching operations.

[0032] Furthermore, as shown in Figure 1, multiple resistors are placed between the relays, and the closure of the relays is detected by measuring the voltage across these resistors. Although this detection circuit can detect relays, it uses a large number of electronic components, resulting in higher costs.

[0033] Based on this, some embodiments of this disclosure provide a relay status detection circuit. As shown in FIG2, the relay status detection circuit 100 includes: a power battery pack 1, multiple relays 2, a voltage acquisition unit 3, multiple voltage divider circuits 4, and a controller 5.

[0034] Multiple relays 2 are connected in series between the positive and negative terminals of the power battery pack 1; each of the two ends of the relay 2 has a detection point. That is, for two adjacent relays 2, the connection point of the two relays shares a detection point because the potential at that location is the same.

[0035] The first voltage terminal 401 of the voltage divider circuit 4 is electrically connected to the voltage acquisition terminal U of the voltage acquisition device 3; the second voltage terminal 402 of the voltage divider circuit 4 is electrically connected to a detection point; and the third voltage terminal 403 of the voltage divider circuit 4 is electrically connected to the reference voltage terminal UVREF.

[0036] Voltage acquisition unit 3 is configured to acquire the voltage value of the first voltage terminal 401 of voltage divider circuit 4.

[0037] In other words, each detection point corresponds to a voltage divider circuit, and the voltage at the detection point is calculated from the voltage at the first voltage terminal of the voltage divider circuit. Related technologies connect a detection circuit across the relay terminals to determine whether the relay is closed; the more relays there are, the more detection circuits are required. Some embodiments of this disclosure have simpler detection circuits than those in related technologies, using a voltage divider circuit and a voltage acquisition device to detect the relay, resulting in lower costs and facilitating further promotion.

[0038] Furthermore, in related technologies, each relay has a detection circuit connected to both ends, and all the detection circuits form a large loop, which can easily lead to a decrease in insulation resistance. However, some embodiments of this disclosure connect a detection point to a voltage divider circuit, thus avoiding the problem of decreased insulation resistance.

[0039] In some embodiments, a single detection point may correspond to multiple voltage divider circuits to prevent damage to the voltage divider circuits. This way, if one voltage divider circuit fails, a backup voltage divider circuit can be used for detection.

[0040] Controller 5 is electrically connected to voltage acquisition unit 3. The controller is configured to: receive the voltage value of the first voltage terminal 401 of the voltage divider circuit 4 acquired by the voltage acquisition unit 3; and, based on the voltage value of the first voltage terminal 401 of the voltage divider circuit 4 connected to the detection points at both ends of the relay under test and the voltage value of the reference voltage terminal UVREF, obtain the voltage values ​​of the detection points at both ends of the relay under test; and determine the state of the relay under test based on the voltage values ​​of the detection points at both ends of the relay under test. For example, the controller determines whether the relay under test is closed based on whether the voltage values ​​of the detection points at both ends of the relay under test are equal.

[0041] Here, the state of the relay under test includes both closed and open states. The relay under test is one of multiple relays, and at least one of the detection points at both ends of the relay under test is energized.

[0042] For example, the relay under test is the first relay. At this time, the detection point corresponding to the first terminal of the first relay is connected to the positive terminal of the power battery pack 1. That is, one detection point in the first relay is in a powered-on state. The second voltage terminal 402 of a voltage divider circuit is electrically connected to this detection point, and the first voltage terminal 401 of the voltage divider circuit is electrically connected to the voltage acquisition terminal U of the voltage acquisition device 3. The voltage acquisition device 3 acquires the voltage value of the first voltage terminal 401 of the voltage divider circuit in real time and transmits this voltage value to the controller 5. Here, the first relay can be understood as the relay closest to the positive terminal of the power battery pack 1 among the multiple relays in Figure 2.

[0043] If the voltage value of the first voltage terminal 401 is UX, the voltage value of the reference voltage terminal UVREF is UVREF, the resistance between the first and second voltage terminals in the voltage divider circuit is RX, and the resistance between the first and third voltage terminals in the voltage divider circuit is RY, then the current of the voltage divider circuit is I = (UX - UVREF) / RY, and the voltage between the second and third voltage terminals of the voltage divider circuit is U = I × (RX + RY), that is, U = (UX - UVREF) × (RX + RY) / RY, thus the voltage value of the detection point can be obtained.

[0044] Similarly, the controller can calculate the voltage value of the other detection point of the first relay, and determine whether the first relay is closed by comparing whether the voltage values ​​of the two detection points are equal; if the voltage values ​​of the two detection points are the same, the first relay is closed; if the voltage values ​​of the two detection points are different, the first relay is open.

[0045] Based on the above solutions, some embodiments of this disclosure provide a relay status detection circuit. This detection circuit can obtain the voltage value of the first voltage terminal of the voltage divider circuit in real time through multiple voltage divider circuits and a voltage acquisition device. The controller can calculate the voltage value of each detection point using the voltage value of the first voltage terminal of the voltage divider circuit, the resistance value of the voltage divider circuit, and the voltage value of the reference voltage terminal. The controller determines whether the relay is closed by comparing the voltage values ​​at both ends of the relay to see if they are the same. Compared with detection circuits in related technologies, the circuits of some embodiments of this disclosure can achieve voltage detection without an isolating switch, and the test voltage at each test point can be reused multiple times, reducing costs by more than 50%.

[0046] Furthermore, compared to related technologies that require sampling the voltage at each test point to obtain the status of each relay, some embodiments of this disclosure allow the voltage at each test point to be used multiple times, avoiding multiple samplings of a single test point and significantly reducing the impact of the circuit on the system insulation.

[0047] In some embodiments, as shown in FIG3, the plurality of relays 2 include at least one of a first relay S1 and a second relay S2. For example, the relay state detection circuit 100 includes a first relay S1, or the relay state detection circuit 100 includes a second relay S2, or the relay state detection circuit 100 includes both a first relay S1 and a second relay S2.

[0048] The first terminal of the first relay S1 is electrically connected to the positive terminal of the power battery pack 1; the first terminal of the first relay S1 is provided with a first detection point A, and the second terminal of the first relay S1 is provided with a second detection point C.

[0049] The first terminal of the second relay S2 is electrically connected to the negative terminal of the power battery pack 1; the first terminal of the second relay S2 is provided with a third detection point B, and the second terminal of the second relay S2 is provided with a fourth detection point D.

[0050] The reference voltage terminal UVREF includes: a first reference voltage terminal UVREF1 and a second reference voltage terminal UVREF2. The first reference voltage terminal UVREF1 is electrically connected to the ground terminal of the voltage acquisition unit 3; the second reference voltage terminal UVREF2 is electrically connected to the power supply terminal of the voltage acquisition unit 3.

[0051] In other words, the first reference voltage terminal UVREF1 can be understood as the ground terminal.

[0052] The voltage of the second reference voltage terminal UVREF2 is provided by an external power supply. One end of the external power supply is electrically connected to the second reference voltage terminal UVREF2, and the other end is electrically connected to the first reference voltage terminal UVREF1.

[0053] The plurality of voltage divider circuits 4 include at least one of a first voltage divider circuit 41, a third voltage divider circuit 43, a fourth voltage divider circuit 44, and a second voltage divider circuit 42.

[0054] The first voltage terminal of the first voltage divider circuit 41 is electrically connected to the first voltage acquisition terminal U1 of the voltage acquisition device 3, the second voltage terminal of the first voltage divider circuit 41 is electrically connected to the second detection point C, and the third voltage terminal of the first voltage divider circuit 41 is electrically connected to the second reference voltage terminal UVREF2. As can be seen from Figure 3, the first voltage divider circuit is connected to the second detection point C through detection point C1. C1 and C can be regarded as a detection point, but they are separated in the figure for ease of drawing.

[0055] The first voltage terminal of the second voltage divider circuit 42 is electrically connected to the second voltage acquisition terminal U2 of the voltage acquisition unit 3; the second voltage terminal of the second voltage divider circuit 42 is electrically connected to the fourth detection point D; and the third voltage terminal of the second voltage divider circuit 42 is electrically connected to the second reference voltage terminal UVREF2. As can be seen from Figure 3, the second voltage divider circuit is connected to the fourth detection point D through detection point D1. D1 and D can be regarded as a detection point, but they are separated in the figure for ease of drawing.

[0056] The first voltage terminal of the third voltage divider circuit 43 is electrically connected to the third voltage acquisition terminal U3 of the voltage acquisition unit 3; the second voltage terminal of the third voltage divider circuit 43 is electrically connected to the second detection point C; the third voltage terminal of the third voltage divider circuit 43 is electrically connected to the first reference voltage terminal UVREF1; and it is also electrically connected to the third detection point B. As can be seen from Figure 3, the first voltage divider circuit is connected to the second detection point C through detection point C2. C1, C2, and C can be regarded as a detection point, but they are separated in the figure for ease of drawing.

[0057] The first voltage terminal of the fourth voltage divider circuit 44 is electrically connected to the fourth voltage acquisition terminal U4 of the voltage acquisition device 3; the second voltage terminal of the fourth voltage divider circuit 44 is electrically connected to the first detection point A; the third voltage terminal of the fourth voltage divider circuit 44 is electrically connected to the first reference voltage terminal UVREF1 and also electrically connected to the third detection point B.

[0058] If the solution in some embodiments of this disclosure only has a first relay S1, then the voltage divider circuit needs to use a first voltage divider circuit 41, a third voltage divider circuit 43, and a fourth voltage divider circuit 44; if the solution in some embodiments of this disclosure only has a second relay S2, then the voltage divider circuit needs to use a second voltage divider circuit 42; if the solution in some embodiments of this disclosure has both a first relay S1 and a second relay S2, then the voltage divider circuit needs to use a first voltage divider circuit 41, a second voltage divider circuit 42, a third voltage divider circuit 43, and a fourth voltage divider circuit 44.

[0059] The first voltage divider circuit 41 includes: a first resistor R1 and a second resistor R2. The first end of the first resistor R1 is electrically connected to the second detection point C, and the second end of the first resistor R1 is electrically connected to the first voltage acquisition terminal U1 of the voltage acquisition device 3; the first end of the second resistor R2 is electrically connected to the second end of the first resistor R1, and the second end of the second resistor R2 is electrically connected to the second reference voltage terminal UVREF2.

[0060] According to the first voltage divider circuit 41, the voltage value of the second detection point C can be obtained as (U1-UVREF2)×(R1+R2) / R2+UVREF2.

[0061] The second voltage divider circuit 42 includes a third resistor R3 and a fourth resistor R4. The first end of the third resistor R3 is electrically connected to the fourth detection point D, and the second end of the third resistor R3 is electrically connected to the second voltage acquisition terminal U2 of the voltage acquisition unit 3. The first end of the fourth resistor R4 is electrically connected to the second end of the third resistor R3, and the second end of the fourth resistor R4 is electrically connected to the second reference voltage terminal UVREF2.

[0062] According to the second voltage divider circuit 42, the voltage value of the fourth detection point D can be obtained as (U2-UVREF2)×(R3+R4) / R4+UVREF2.

[0063] The third voltage divider circuit 43 includes a fifth resistor R5 and a sixth resistor R6. The first end of the fifth resistor R5 is electrically connected to the second detection point C, and the second end of the fifth resistor R5 is electrically connected to the third voltage acquisition terminal U3 of the voltage acquisition device 3; the first end of the sixth resistor R6 is electrically connected to the second end of the fifth resistor R5, and the second end of the sixth resistor R6 is electrically connected to the first reference voltage terminal UVREF1.

[0064] According to the third voltage divider circuit 43, the voltage value at the second detection point C can be obtained as U3×(R5+R6) / R6. Since UVREF1 is equivalent to the ground terminal, it can be regarded as 0V.

[0065] The fourth voltage divider circuit 44 includes a seventh resistor R7 and an eighth resistor R8. The first end of the seventh resistor R7 is electrically connected to the first detection point A, and the second end of the seventh resistor R7 is electrically connected to the fourth voltage acquisition terminal U4 of the voltage acquisition unit 3; the first end of the eighth resistor R8 is electrically connected to the second end of the seventh resistor R7, and the second end of the eighth resistor R8 is electrically connected to the first reference voltage terminal UVREF1.

[0066] According to the fourth voltage divider circuit 44, the voltage value at the first detection point A can be obtained as U4×(R7+R8) / R8. Since UVREF1 is equivalent to the ground terminal, it can be regarded as 0V.

[0067] When detecting the first relay, the controller 5 receives the voltage value of the first voltage terminal of the third voltage divider circuit 43 and the voltage value of the first voltage terminal of the fourth voltage divider circuit 44 collected by the voltage collector 3; based on the voltage value of the first voltage terminal of the third voltage divider circuit 43 and the voltage value of the reference voltage terminal, the voltage value of the second detection point C of the first relay S1 is obtained, which is U3×(R5+R6) / R6.

[0068] Based on the voltage value at the first voltage terminal and the voltage value at the reference voltage terminal of the fourth voltage divider circuit 44, the voltage value at the first detection point A of the first relay S1 is obtained, which is U4×(R7+R8) / R8.

[0069] The controller 5 determines whether the voltage values ​​of U3×(R5+R6) / R6 and U4×(R7+R8) / R8 are equal, and thus determines whether the first relay S1 is closed. If the voltage values ​​of U3×(R5+R6) / R6 and U4×(R7+R8) / R8 are equal, the first relay S1 is closed; if the voltage values ​​of U3×(R5+R6) / R6 and U4×(R7+R8) / R8 are not equal, the first relay S1 is open.

[0070] In some embodiments, as shown in FIG4, the plurality of relays 2 further include: a plurality of external relays 21.

[0071] The multiple voltage divider circuits 4 also include a voltage divider circuit connected to the external relays 21; the multiple external relays 21 are connected in series and between the first relay S1 and the second relay S2; the first voltage terminal of the voltage divider circuit connected to the external relays 21 is electrically connected to the voltage acquisition terminal U of the voltage acquisition device 3, the second voltage terminal 402 of the voltage divider circuit connected to the external relays 21 is electrically connected to the detection point of the external relays 21, and the third voltage terminal of the voltage divider circuit connected to the external relays 21 is electrically connected to the second reference voltage terminal UVREF2. In other words, when the circuit also includes external relays 21, the controller needs to detect them one by one.

[0072] As shown in Figure 4, the plurality of outer relays 21 include: a fourth relay S4; the plurality of outer relays 21 also include: at least one of a third relay S3 and a fifth relay S5.

[0073] In other words, the multiple outer relays 21 can be the fourth relay S4 and the third relay S3, or the fourth relay S4 and the fifth relay S5, or the third relay S3, the fourth relay S4 and the fifth relay S5.

[0074] In some embodiments, the fourth relay S4 is a charging relay. Depending on the application scenario and requirements, charging relays can be classified into various types, including pre-charge relays, fast-charge relays, and ordinary charging relays.

[0075] The first terminal of the third relay S3 is electrically connected to the second terminal of the first relay S1, and the second terminal of the third relay S3 is provided with a fifth detection point E; the first terminal of the fourth relay S4 is electrically connected to the second terminal of the second relay S2, and the second terminal of the fourth relay S4 is provided with a sixth detection point F; the first terminal of the fifth relay S5 is electrically connected to the second terminal of the third relay S3, and the second terminal of the fifth relay S5 is electrically connected to the second terminal of the fourth relay S4.

[0076] The multiple voltage divider circuits also include at least one of a fifth voltage divider circuit 45 and a sixth voltage divider circuit 46.

[0077] In other words, the multiple voltage divider circuits also include a fifth voltage divider circuit 45, or a sixth voltage divider circuit 46, or both the fifth voltage divider circuit 45 and the sixth voltage divider circuit 46. The specific configuration of the multiple voltage divider circuits needs to be used in conjunction with relays.

[0078] The first voltage terminal of the fifth voltage divider circuit 45 is electrically connected to the fifth voltage acquisition terminal U5 of the voltage acquisition unit 3; the second voltage terminal of the fifth voltage divider circuit 45 is electrically connected to the fifth detection point E; and the third voltage terminal of the fifth voltage divider circuit 45 is electrically connected to the second reference voltage terminal UVREF2.

[0079] The first voltage terminal of the sixth voltage divider circuit 46 is electrically connected to the sixth voltage acquisition terminal U6 of the voltage acquisition unit 3; the second voltage terminal of the sixth voltage divider circuit 46 is electrically connected to the sixth detection point F; and the third voltage terminal of the sixth voltage divider circuit 46 is electrically connected to the second reference voltage terminal UVREF2.

[0080] As shown in Figure 4, the fifth voltage divider circuit is connected to the fifth detection point E through detection point E1. E1 and E can be considered as one detection point, but they are separated in the figure for ease of drawing. As shown in Figure 4, the sixth voltage divider circuit is connected to the sixth detection point F through detection point F1. F1 and F can be considered as one detection point, but they are separated in the figure for ease of drawing.

[0081] In some embodiments, as shown in FIG4, the fifth voltage divider circuit 45 includes a ninth resistor R9 and a tenth resistor R10.

[0082] The first terminal of the ninth resistor R9 is electrically connected to the fifth detection point E, and the second terminal of the ninth resistor R9 is electrically connected to the fifth voltage acquisition terminal U5 of the voltage acquisition device 3. The first terminal of the tenth resistor R10 is electrically connected to the second terminal of the ninth resistor R9, and the second terminal of the tenth resistor R10 is electrically connected to the second reference voltage terminal UVREF2.

[0083] According to the fifth voltage divider circuit 45, the voltage value of the fifth detection point E can be obtained as (U5-UVREF2)×(R9+R10) / R10+UVREF2.

[0084] The sixth voltage divider circuit 46 includes: the eleventh resistor R11 and the twelfth resistor R12.

[0085] The first end of the eleventh resistor R11 is electrically connected to the sixth detection point F, and the second end of the eleventh resistor R11 is electrically connected to the sixth voltage acquisition terminal U6 of the voltage acquisition device 3. The first end of the twelfth resistor R12 is electrically connected to the second end of the eleventh resistor R11, and the second end of the twelfth resistor R12 is electrically connected to the second reference voltage terminal UVREF2.

[0086] According to the sixth voltage divider circuit 46, the voltage value of the sixth detection point F can be obtained as (U6-UVREF2)×(R11+R12) / R12+UVREF2.

[0087] When testing the third relay S3, the voltage values ​​of the second detection point C and the fifth detection point E are required. The controller 5 receives the voltage value of the first voltage terminal of the fifth voltage divider circuit 45 collected by the voltage acquisition unit 3; based on the voltage value of the first voltage terminal of the fifth voltage divider circuit 45 and the voltage value of the reference voltage terminal, the voltage value of the fifth detection point E of the third relay S3 is obtained, which is (U5-UVREF2)×(R9+R10) / R10+UVREF2.

[0088] Based on the voltage value at the first voltage terminal and the voltage value at the reference voltage terminal of the first voltage divider circuit 41, the voltage value at the second detection point C of the first relay S1 is obtained, which is (U1-UVREF2)×(R1+R2) / R2+UVREF2.

[0089] Controller 5 determines whether the voltage values ​​of (U5-UVREF2)×(R9+R10) / R10+UVREF2 and (U1-UVREF2)×(R1+R2) / R2+UVREF2 are equal, thereby determining whether the third relay S3 is closed.

[0090] If the voltage values ​​of (U5-UVREF2)×(R9+R10) / R10+UVREF2 and (U1-UVREF2)×(R1+R2) / R2+UVREF2 are equal, then the third relay S3 is closed; if the voltage values ​​of (U5-UVREF2)×(R9+R10) / R10+UVREF2 and (U1-UVREF2)×(R1+R2) / R2+UVREF2 are not equal, then the third relay S3 is open.

[0091] When detecting the fourth relay S4, the voltage values ​​of the fourth detection point D and the sixth detection point F are required. The controller 5 receives the voltage value of the first voltage terminal of the second voltage divider circuit 42 collected by the voltage collector 3; based on the voltage value of the first voltage terminal of the second voltage divider circuit 42 and the voltage value of the reference voltage terminal, the voltage value of the fourth detection point D of the fourth relay S4 is obtained, which is (U2-UVREF2)×(R3+R4) / R4+UVREF2.

[0092] Based on the voltage value of the first voltage terminal and the voltage value of the reference voltage terminal of the sixth voltage divider circuit 46, the voltage value of the sixth detection point F of the fourth relay S4 is obtained, which is (U6-UVREF2)×(R11+R12) / R12+UVREF2.

[0093] Controller 5 determines whether the voltage values ​​of (U2-UVREF2)×(R3+R4) / R4+UVREF2 and (U6-UVREF2)×(R11+R12) / R12+UVREF2 are equal, thereby determining whether the fourth relay S4 is closed.

[0094] If the voltage values ​​of (U2-UVREF2)×(R3+R4) / R4+UVREF2 and (U6-UVREF2)×(R11+R12) / R12+UVREF2 are equal, then the fourth relay S4 is closed; if the voltage values ​​of (U2-UVREF2)×(R3+R4) / R4+UVREF2 and (U6-UVREF2)×(R11+R12) / R12+UVREF2 are not equal, then the fourth relay S4 is open.

[0095] When testing the fifth relay S5, the voltage values ​​of the fifth detection point E and the sixth detection point F are required. The controller 5 receives the voltage value of the first voltage terminal of the fifth voltage divider circuit 45 collected by the voltage acquisition unit 3; based on the voltage value of the first voltage terminal of the fifth voltage divider circuit 45 and the voltage value of the reference voltage terminal, the voltage value of the fifth detection point E of the fifth relay S5 is obtained, which is (U5-UVREF2)×(R9+R10) / R10+UVREF2.

[0096] Based on the voltage value at the first voltage terminal and the voltage value at the reference voltage terminal of the sixth voltage divider circuit 46, the voltage value at the sixth detection point F of the fifth relay S5 is obtained, which is (U6-UVREF2)×(R11+R12) / R12+UVREF2.

[0097] Controller 5 determines whether the voltage values ​​of (U5-UVREF2)×(R9+R10) / R10+UVREF2 and (U6-UVREF2)×(R11+R12) / R12+UVREF2 are equal, thereby determining whether the fifth relay S5 is closed.

[0098] If the voltage values ​​of (U5-UVREF2)×(R9+R10) / R10+UVREF2 and (U6-UVREF2)×(R11+R12) / R12+UVREF2 are equal, then the fifth relay S5 is closed; if the voltage values ​​of (U5-UVREF2)×(R9+R10) / R10+UVREF2 and (U6-UVREF2)×(R11+R12) / R12+UVREF2 are not equal, then the fifth relay S5 is open.

[0099] It should be noted that R1 to R12 in the above formula refer to the resistance values ​​of the first to twelfth resistors, U1 to U6 in the above formula refer to the voltage values ​​of the first voltage terminals of the multiple voltage divider circuits collected by the first to sixth voltage acquisition terminals of the voltage acquisition device, and UVREF2 in the above formula refers to the voltage value of the second reference voltage terminal.

[0100] In some embodiments, as shown in FIG5, the relay state detection circuit 100 further includes a charging gun 6.

[0101] The first output terminal of the charging gun 6 is electrically connected to one end of one of the multiple outer relays, and the second output terminal of the charging gun 6 is electrically connected to one end of another of the multiple outer relays.

[0102] The charging gun 6 is configured to energize the detection points of some of the external relays. Furthermore, the charging gun can charge the power battery pack.

[0103] As shown in Figure 6, when the outer relays include: the third relay S3, the fourth relay S4 and the fifth relay S5, the relay status detection circuit also includes: at least two power-on circuits 7.

[0104] The first end of the power-on circuit 7 is electrically connected to the positive terminal of the power battery pack 1. The second end of one of the power-on circuits 7 is electrically connected to the fourth detection point D. The second ends of the remaining power-on circuits are electrically connected to the detection points between two adjacent outer relays.

[0105] The power-on circuit is configured to power on the detection point of the second relay S2 or the detection point of some of the outer relays.

[0106] In other words, at least one of the two power-on circuits 7 needs to be located at the connection between the second and fourth relays, and the other power-on circuit needs to be located at the connection between the third and fifth relays.

[0107] For example, if the relay status detection circuit 100 includes 4 external relays, the relay status detection circuit 100 requires at least 3 power-on circuits; if the relay status detection circuit 100 includes N external relays, when N is an odd number, the relay status detection circuit 100 requires at least (N+1) / 2 power-on circuits; when N is an even number, the relay status detection circuit 100 requires at least N / 2+1 power-on circuits.

[0108] During controller testing, at least one of the test points at both ends of the relay under test must be energized. The first terminal of the first relay S1 is electrically connected to the positive terminal of the power battery pack and is already energized, thus meeting the testing conditions. The second relay S2 requires an energizing circuit to connect the fourth test point to the positive terminal of the power battery pack. With the first relay disconnected, the third relay requires another energizing circuit to connect the fifth test point to the positive terminal of the power battery pack. Furthermore, since the third relay is connected to the fifth relay, connecting the fifth test point to the positive terminal of the power battery pack through another energizing circuit also satisfies the testing conditions for the fifth relay.

[0109] If the relay status detection circuit 100 includes a third relay S3 and a fourth relay S4, or if the relay status detection circuit 100 includes a fifth relay S5 and a fourth relay S4, then at least one power-on circuit is required. The first end of the power-on circuit 7 is electrically connected to the positive terminal of the power battery pack 1, and the second end of the power-on circuit 7 is electrically connected to the detection point between two adjacent outer relays 21.

[0110] In this way, the detection point between the third relay S3 and the fourth relay S4 can be connected, or the detection point between the fifth relay S5 and the fourth relay S4 can be connected. In this case, the power-on circuit 7 is configured to power on the detection point of the outer relay 21.

[0111] As shown in Figure 6, the multiple outer relays 21 include: a third relay S3, a fourth relay S4, and a fifth relay S5.

[0112] At least two power-on circuits 7 include: a first power-on circuit 71 and a second power-on circuit 72.

[0113] The first terminal of the first power-on circuit 71 is electrically connected to the positive terminal of the power battery pack 1, and the second terminal of the first power-on circuit 71 is electrically connected to the second terminal of the third relay S3.

[0114] The first terminal of the second power-on circuit 72 is electrically connected to the positive terminal of the power battery pack 1, and the second terminal of the second power-on circuit 72 is electrically connected to the second terminal of the second relay S2.

[0115] The first power-on circuit 71 includes a thirteenth resistor R13 and a first switch K1. The first end of the thirteenth resistor R13 is electrically connected to the positive terminal of the power battery pack 1; the first end of the first switch K1 is electrically connected to the second end of the thirteenth resistor R13, and the second end of the first switch K1 is electrically connected to the second end of the third relay S3.

[0116] The second power-on circuit 72 includes: a fourteenth resistor R14 and a second switch K2. The first end of the fourteenth resistor R14 is electrically connected to the positive terminal of the power battery pack 1; the first end of the second switch K2 is electrically connected to the second end of the fourteenth resistor R14, and the second end of the second switch K2 is electrically connected to the second end of the second relay S2.

[0117] In this case, controller 5 is also configured to control the opening and closing of the first switch K1 and the second switch K2.

[0118] When the first switch K1 is closed, the detection point connected to the first power-on circuit is in a powered-on state; when the second switch K2 is closed, the detection point connected to the second power-on circuit is in a powered-on state.

[0119] In summary, there are three ways to power on the device. The first way is to power it through the battery pack, which is applicable to the first relay mentioned above.

[0120] The second method is to power on the second detection point C and the sixth detection point F through the charging gun when the first relay is off. This method is applicable to the third relay S3, the fourth relay S4 and the fifth relay S5.

[0121] The third method is to power on via the power-on circuit. When at least one of the first and second relays is disconnected, and when the charging gun has no output voltage, the controller powers on the detection points of the second relay S2, the third relay S3, the fourth relay S4, and the fifth relay S5 by closing the first and second switches.

[0122] In some embodiments, as shown in FIG6, the relay state detection circuit further includes a third switch K3. The first terminal of the third switch K3 is electrically connected to the first terminal of the seventh resistor R7, and the second terminal of the third switch K3 is electrically connected to the positive terminal of the power battery pack 1.

[0123] When controller 5 turns on the third switch K3, controller 5 can calculate the voltage across the power battery pack using the fourth voltage divider circuit. Since the negative terminal of the power battery pack is connected to the first reference voltage terminal UVREF1, the voltage across the power battery pack is the voltage at the first detection point A.

[0124] In some embodiments, as shown in FIG6, the relay state detection circuit 100 is provided with a motor 8.

[0125] The first end of the motor 8 is electrically connected to the second end of the first relay S1, the second end of the motor 8 is electrically connected to the second end of the third relay S3, and the third end of the motor 8 is electrically connected to the second end of the second relay S2.

[0126] In some embodiments of this disclosure, the motor is the load of the relay status detection circuit, and when the relay is closed, the power battery pack 1 supplies power to the motor 8.

[0127] In some embodiments, as shown in FIG7, the relay state detection circuit 100 further includes a seventh voltage divider circuit 47.

[0128] The first voltage terminal of the seventh voltage divider circuit 47 is electrically connected to the seventh voltage acquisition terminal U7 of the voltage acquisition unit 3; the second voltage terminal of the seventh voltage divider circuit 47 is electrically connected to the fourth detection point D; and the third voltage terminal of the seventh voltage divider circuit 47 is electrically connected to the second reference voltage terminal UVREF2. As shown in Figure 7, the second voltage divider circuit is connected to the fourth detection point D through detection point D2. D2 and D can be considered as a single detection point, but they are separated in the figure for ease of diagramming.

[0129] The seventh voltage divider circuit 47 includes a fifteenth resistor R15 and a sixteenth resistor R16. The first end of the fifteenth resistor R15 is electrically connected to the fourth detection point D, and the second end of the fifteenth resistor R15 is electrically connected to the seventh voltage acquisition terminal U7 of the voltage acquisition unit 3. The first end of the sixteenth resistor R16 is electrically connected to the second end of the fifteenth resistor R15, and the second end of the sixteenth resistor R16 is electrically connected to the second reference voltage terminal UVREF2.

[0130] According to the seventh voltage divider circuit 47, the voltage value of the fourth detection point D can be obtained as (U7-UVREF2)×(R15+R16) / R16+UVREF2.

[0131] In other words, in some embodiments of this disclosure, the voltage value of the fourth detection point D can be obtained through both the second voltage divider circuit 42 and the seventh voltage divider circuit 47. It can be determined first whether the voltage values ​​of detection points D1 and D2 are the same, and then whether the second relay is closed. This improves the accuracy and stability of the determination.

[0132] Similarly, in some embodiments of this disclosure, the voltage value of the second detection point C can be obtained through both the first voltage divider circuit 41 and the third voltage divider circuit 43. It can be determined first whether the voltage values ​​of detection points C1 and C2 are the same, and then it can be determined whether the first relay S1 is closed. This determination process can be seen in Figure 8, and includes steps S101 to S109:

[0133] In step S101, the controller controls the third switch to close.

[0134] In step S102, the voltage acquisition device acquires the voltage values ​​of the first voltage acquisition terminal U1, the third voltage acquisition terminal U3, and the fourth voltage acquisition terminal U4.

[0135] In step S103, the controller receives the voltage values ​​from the first voltage acquisition terminal U1, the third voltage acquisition terminal U3, and the fourth voltage acquisition terminal U4, and calculates the voltage values ​​of the first detection point A, detection point C1, and detection point C2.

[0136] In step S104, the controller determines whether the voltage values ​​of the first detection point A and the detection point C1 are equal.

[0137] If yes, proceed to step S105; otherwise, proceed to step S107.

[0138] In step S105, the controller determines whether the voltage values ​​of the first detection point A and the detection point C2 are equal.

[0139] If yes, proceed to step S106; otherwise, proceed to step S107.

[0140] In step S106, the first relay S1 is closed.

[0141] In step S107, the first relay S1 is disconnected.

[0142] In step S108, the results of the two judgments are different.

[0143] In other words, when the voltage values ​​at detection point C1 and detection point C2 are different, it is impossible to determine which one is faulty, and no action is taken.

[0144] In step S109, the state of the first relay is uncertain.

[0145] Similarly, two voltage divider circuits can be set up for other detection points to perform dual judgment. Subsequent embodiments will not be elaborated further.

[0146] In some embodiments, as shown in FIG9, when the relay state detection circuit 100 does not include the second relay S2, the second switch K2 should be connected to the detection point F. In this case, the controller 5 determines the state of the fourth relay S4 as follows:

[0147] The controller 5 first determines whether the charging gun has an output. If the charging gun has an output, it collects the voltage value of the sixth voltage acquisition terminal U6 and determines whether the sixth voltage acquisition terminal U6 is equal to (UVREF2-UVREF1)×R11 / (R11+R12). If they are equal, it proves that the fourth relay S4 is closed or stuck. Otherwise, it proves that the fourth relay S4 is not closed or stuck.

[0148] If the charging gun has no output, close the second switch K2 and determine whether the sixth voltage acquisition terminal U6 is equal to (UVREF2-UVREF1)×R11 / (R11+R12). If they are equal, it proves that the fourth relay S4 is closed or stuck. Otherwise, it proves that the fourth relay S4 is not closed or stuck.

[0149] In some embodiments, as shown in FIG10, when the relay state detection circuit 100 does not include the first relay S1, the fourth relay S4 should be in the position shown in FIG10. In this case, the controller 5 determines the adhesion mode of the fourth relay S4 as follows:

[0150] The controller 5 first collects the voltage values ​​of the first voltage acquisition terminal U1 and the fourth voltage acquisition terminal U4, and then calculates the voltage value of the second detection point C according to the formula (U1-UVREF2)×(R1+R2) / R2+UVREF2, and calculates the voltage value of the first detection point A according to the formula U4×(R7+R8) / R8.

[0151] C: (U1-UVREF2)×(R1+R2) / R2+UVREF2.

[0152] A: U4×(R7+R8) / R8.

[0153] The controller 5 determines whether the voltage value at the second detection point C is equal to the voltage value at the first detection point A. If they are equal, it proves that the fourth relay S4 is stuck; otherwise, it proves that the fourth relay S4 is not stuck.

[0154] It should be noted that Figures 9 and 10 are only two embodiments. The outer relay may include any one of the third relay S3 and the fifth relay S5, or may include the third relay S3 and the fifth relay S5, or may include multiple other outer relays; and the relay state detection circuit 100 may include any one of the first relay S1 and the second relay S2, or may include the first relay S1 and the second relay S2. This disclosure does not limit this.

[0155] As shown in Figure 11, some embodiments of this disclosure provide a detection method for a relay state detection circuit, which is applied to the aforementioned relay state detection circuit. The method includes the following steps S1 to S3:

[0156] In step S1, the controller 5 receives the voltage value of the first voltage terminal of the voltage divider circuit 4 collected by the voltage collector 3.

[0157] In step S2, the controller 5 obtains the voltage values ​​of the detection points at both ends of the relay under test based on the voltage values ​​of the first voltage terminal and the reference voltage terminal of the voltage divider circuit connected to the detection points at both ends of the relay under test.

[0158] In step S3, the controller 5 determines the state of the relay under test based on the voltage values ​​at the detection points at both ends of the relay under test.

[0159] Here, the state of the relay under test includes both closed and open states. The relay under test is one of multiple relays, and at least one of the detection points at both ends of the relay under test is energized.

[0160] In some embodiments, as shown in FIG12, when the relay to be tested is the first relay S1, the method includes steps S11 to S16:

[0161] In step S11, the third switch is closed by the controller.

[0162] In step S12, U3 and U4 are collected by a voltage acquisition device.

[0163] The controller 5 receives the voltage value of the first voltage terminal of the third voltage divider circuit 43 and the voltage value of the first voltage terminal of the fourth voltage divider circuit 44 from the voltage acquisition unit 3.

[0164] In step S13, the controller receives U3 and U4 and calculates the voltage values ​​of the first detection point A and the second detection point C.

[0165] The controller 5 obtains the voltage value of the second detection point C of the first relay S1 based on the voltage value of the first voltage terminal of the third voltage divider circuit 43 and the voltage value of the reference voltage terminal. The controller 5 obtains the voltage value of the first detection point A of the first relay S1 based on the voltage value of the first voltage terminal of the fourth voltage divider circuit 44 and the voltage value of the reference voltage terminal.

[0166] A: U4×(R7+R8) / R8.

[0167] C: U3×(R5+R6) / R6.

[0168] In step S14, the controller determines whether the voltage values ​​of the first detection point A and the second detection point C are equal.

[0169] The controller determines whether the first relay S1 is closed based on whether the voltage values ​​at the detection points across the two ends of the first relay S1 are equal. If they are equal, the process proceeds to step S15; otherwise, it proceeds to step S16.

[0170] The controller determines whether U4×(R7+R8) / R8 is equal to U3×(R5+R6) / R6.

[0171] In step S15, it is determined that the first relay S1 is closed.

[0172] In step S16, it is determined that the first relay S1 is disconnected.

[0173] In some embodiments, as shown in FIG13, when the relay to be tested is the second relay S2, the method includes steps S21 to S26:

[0174] In step S21, the second switch is closed by the controller.

[0175] In step S22, U2 is acquired by voltage acquisition device 3.

[0176] The voltage value at the first voltage terminal of the second voltage divider circuit 42 is collected by the voltage acquisition device 3.

[0177] In step S23, the controller receives U2 and calculates the voltage value of the fourth detection point D.

[0178] The voltage value of the fourth detection point D of the second relay S2 is obtained based on the voltage value of the first voltage terminal of the second voltage divider circuit 42 and the voltage value of the second reference voltage terminal UVREF2.

[0179] D: (U2-UVREF2)×(R3+R4) / R4+UVREF2. Based on the closing of the second switch, the actual voltage value of the first detection point A is calculated as: (U2-UVREF2)×(R3+R4+R14) / R4+UVREF2.

[0180] Preset formula: (UVREF2-UVREF2×R4 / (R3+R4))×(R3+R4+R14) / R4+UVREF2.

[0181] In step S24, the controller determines whether the voltage value of the fourth detection point D and the preset formula are equal.

[0182] The controller obtains the voltage value of the fourth detection point D of the second relay S2 according to a preset formula; it determines whether the second relay S2 is closed based on whether the voltage values ​​of the detection points at both ends of the second relay S2 are equal. If they are equal, the process proceeds to step S25; otherwise, it proceeds to step S26.

[0183] The controller determines whether (U2-UVREF2)×(R3+R4+R14) / R4+UVREF2 is equal to (UVREF2-UVREF2×R4 / (R3+R4))×(R3+R4+R14) / R4+UVREF2.

[0184] The preset formula is the voltage value at the fourth detection point D, assuming the second relay is closed.

[0185] In step S25, it is determined that the second relay S2 is closed.

[0186] In step S26, it is determined that the second relay S2 is disconnected.

[0187] As shown in Figures 14 to 16, the relay status detection circuit includes multiple relays, including an outer relay; the relay under test is an outer relay; one detection point of the outer relay is electrically connected to a voltage divider circuit, and the other detection point of the outer relay is electrically connected to another voltage divider circuit.

[0188] In some examples, as shown in Figure 14, when the relay under test is the third relay S3, the method includes steps S301 to S313:

[0189] In step S301, the controller determines whether the first relay is closed.

[0190] If yes, proceed to step S302; otherwise, proceed to step S303.

[0191] In step S302, U1 and U5 are collected by voltage acquisition device 3.

[0192] The voltage values ​​at the first voltage terminal of the first voltage divider circuit and the first voltage terminal of the fifth voltage divider circuit are collected by voltage acquisition device 3.

[0193] In step S303, the controller determines whether the charging gun is outputting voltage.

[0194] If yes, proceed to step S302; otherwise, proceed to step S308.

[0195] In step S304, the controller receives U1 and U5 and calculates the voltage values ​​of the second detection point C and the fifth detection point E.

[0196] The controller obtains the voltage value of one detection point of the outer relay, namely the voltage value of the second detection point C, based on the voltage value of the first voltage terminal and the voltage value of the second reference voltage terminal UVREF2 of a voltage divider circuit electrically connected to one detection point of the outer relay; and obtains the voltage value of another detection point of the outer relay, namely the voltage value of the fifth detection point E, based on the voltage value of the first voltage terminal and the voltage value of the second reference voltage terminal UVREF2 of a voltage divider circuit electrically connected to another detection point of the outer relay.

[0197] C: (U1-UVREF2)×(R1+R2) / R2+UVREF2.

[0198] E: (U5-UVREF2)×(R9+R10) / R10+UVREF2.

[0199] In step S305, the controller determines whether the voltage values ​​of the second detection point C and the fifth detection point E are equal.

[0200] The controller determines whether the third relay is closed based on whether the voltage values ​​at the detection points at both ends of the third relay are equal. If yes, proceed to step S306; otherwise, proceed to step S307.

[0201] The controller determines whether (U1-UVREF2)×(R1+R2) / R2+UVREF2 is equal to (U5-UVREF2)×(R9+R10) / R10+UVREF2.

[0202] In step S306, it is determined that the third relay is closed.

[0203] In step S307, it is determined that the third relay is disconnected.

[0204] In step S308, the first switch is closed by the controller.

[0205] The fifth detection point is powered on via the first power-on circuit.

[0206] In step S309, U1 and U5 are collected by voltage acquisition device 3.

[0207] Voltage acquisition unit 3 acquires the voltage value of the first voltage terminal of the first voltage divider circuit and the voltage value of the first voltage terminal of the fifth voltage divider circuit.

[0208] In step S310, the controller receives U1 and U5 and calculates the voltage values ​​of the second detection point C and the fifth detection point E.

[0209] The controller obtains the voltage value of one detection point of the outer relay, namely the voltage value of the second detection point C, based on the voltage value of the first voltage terminal and the voltage value of the second reference voltage terminal UVREF2 of a voltage divider circuit electrically connected to one detection point of the outer relay; and obtains the voltage value of the other detection point of the outer relay, namely the voltage value of the fifth detection point E, based on the voltage value of the first voltage terminal and the voltage value of the second reference voltage terminal UVREF2 of a voltage divider circuit electrically connected to the other detection point of the outer relay.

[0210] C: (U1-UVREF2)×(R1+R2+R13) / R2+UVREF2.

[0211] E: (U5-UVREF2)×(R9+R10+R13) / R10+UVREF2.

[0212] In step S311, the controller determines whether the voltage values ​​of the second detection point C and the fifth detection point E are equal.

[0213] The controller determines whether the third relay is closed based on whether the voltage values ​​at the detection points at both ends of the third relay are equal. If yes, proceed to step S312; otherwise, proceed to step S313.

[0214] The controller determines whether (U1-UVREF2)×(R1+R2+R13) / R2+UVREF2 is equal to (U5-UVREF2)×(R9+R10+R13) / R10+UVREF2.

[0215] In step S312, it is determined that the third relay is closed.

[0216] In step S313, it is determined that the third relay is disconnected.

[0217] In some examples, as shown in Figure 15, when the relay under test is the fourth relay S4, the method includes steps S401 to S413:

[0218] In step S401, the controller determines whether the charging gun outputs voltage.

[0219] If yes, proceed to step S402; otherwise, proceed to step S403.

[0220] In step S402, U2 and U6 are acquired by voltage acquisition device 3.

[0221] Voltage acquisition unit 3 acquires the voltage value of the first voltage terminal of the second voltage divider circuit and the voltage value of the first voltage terminal of the sixth voltage divider circuit.

[0222] In step S403, the controller determines whether the second relay is closed.

[0223] If yes, proceed to step S402; otherwise, proceed to step S408.

[0224] In step S404, the controller receives U2 and U6 and calculates the voltage values ​​of the fourth detection point D and the sixth detection point F.

[0225] The controller obtains the voltage value of one detection point of the outer relay, namely the voltage value of the fourth detection point D, based on the voltage value of the first voltage terminal and the voltage value of the second reference voltage terminal UVREF2 of a voltage divider circuit electrically connected to one detection point of the outer relay; and obtains the voltage value of the other detection point of the outer relay, namely the voltage value of the sixth detection point F, based on the voltage value of the first voltage terminal and the voltage value of the second reference voltage terminal UVREF2 of a voltage divider circuit electrically connected to the other detection point of the outer relay.

[0226] D: (U2-UVREF2)×(R3+R4) / R4+UVREF2.

[0227] F: (U6-UVREF2)×(R11+R12) / R12+UVREF2.

[0228] In step S405, the controller determines whether the voltage values ​​of the fourth detection point D and the sixth detection point F are equal.

[0229] The controller determines whether the fourth relay is closed based on whether the voltage values ​​at the detection points across the two ends of the fourth relay are equal. If yes, proceed to step S406; otherwise, proceed to step S407.

[0230] The controller determines whether (U2-UVREF2)×(R3+R4) / R4+UVREF2 is equal to (U6-UVREF2)*(R11+R12) / R12+UVREF2.

[0231] In step S406, it is determined that the fourth relay is closed.

[0232] In step S407, it is determined that the fourth relay is disconnected.

[0233] In step S408, the second switch is closed by the controller.

[0234] The fourth detection point is powered on via the second power-on circuit.

[0235] In step S409, U2 and U6 are acquired by voltage acquisition device 3.

[0236] Voltage acquisition unit 3 acquires the voltage value of the first voltage terminal of the second voltage divider circuit and the voltage value of the first voltage terminal of the sixth voltage divider circuit.

[0237] In step S410, the controller receives U2 and U6 and calculates the voltage values ​​of the fourth detection point D and the sixth detection point F.

[0238] The controller obtains the voltage value of one detection point of the outer relay, namely the voltage value of the fourth detection point D, based on the voltage value of the first voltage terminal and the voltage value of the second reference voltage terminal UVREF2 of a voltage divider circuit electrically connected to one detection point of the outer relay; and obtains the voltage value of the other detection point of the outer relay, namely the voltage value of the sixth detection point F, based on the voltage value of the first voltage terminal and the voltage value of the second reference voltage terminal UVREF2 of a voltage divider circuit electrically connected to the other detection point of the outer relay.

[0239] D: (U2-UVREF2)×(R3+R4+R14) / R4+UVREF2.

[0240] F: (U6-UVREF2)×(R11+R12+R14) / R12+UVREF2.

[0241] In step S411, the controller determines whether the voltage values ​​of the fourth detection point D and the sixth detection point F are equal.

[0242] The controller determines whether the fourth relay is closed based on whether the voltage values ​​at the detection points across the two ends of the fourth relay are equal. If yes, proceed to step S412; otherwise, proceed to step S413.

[0243] The controller determines whether (U2-UVREF2)×(R3+R4+R14) / R4+UVREF2 is equal to (U6-UVREF2)×(R11+R12+R14) / R12+UVREF2.

[0244] In step S412, it is determined that the fourth relay is closed.

[0245] In step S413, it is determined that the fourth relay is disconnected.

[0246] In some examples, as shown in Figure 16, when the relay under test is the fifth relay S5, the method includes steps S501 to S520:

[0247] In step S501, the controller determines whether the charging gun is outputting voltage.

[0248] If yes, proceed to step S502; otherwise, proceed to step S503.

[0249] In step S502, voltage acquisition device 3 acquires U5 and U6.

[0250] The voltage values ​​at the first voltage terminals of the fifth voltage divider circuit and the sixth voltage divider circuit are collected by voltage acquisition device 3.

[0251] In step S503, the controller determines whether the second and fourth relays are closed.

[0252] If yes, proceed to step S502; otherwise, proceed to step S508.

[0253] In step S504, the controller receives U5 and U6 and calculates the voltage values ​​of the fifth detection point E and the sixth detection point F.

[0254] The controller obtains the voltage value of one detection point of the outer relay, namely the voltage value of the fifth detection point E, based on the voltage value of the first voltage terminal and the voltage value of the second reference voltage terminal UVREF2 of a voltage divider circuit electrically connected to one detection point of the outer relay; and obtains the voltage value of the other detection point of the outer relay, namely the voltage value of the sixth detection point F, based on the voltage value of the first voltage terminal and the voltage value of the second reference voltage terminal UVREF2 of a voltage divider circuit electrically connected to the other detection point of the outer relay.

[0255] E: (U5-UVREF2)×(R9+R10) / R10+UVREF2.

[0256] F: (U6-UVREF2)×(R11+R12) / R12+UVREF2.

[0257] In step S505, the controller determines whether the voltage values ​​of the fifth detection point E and the sixth detection point F are equal.

[0258] The controller determines whether the fifth relay is closed based on whether the voltage values ​​at the detection points across the two ends of the fifth relay are equal. If yes, proceed to step S506; otherwise, proceed to step S507.

[0259] The controller determines whether (U5-UVREF2)×(R9+R10) / R10+UVREF2 is equal to (U6-UVREF2)×(R11+R12) / R12+UVREF2.

[0260] In step S506, it is determined that the fifth relay is closed.

[0261] In step S507, it is determined that the fifth relay is disconnected.

[0262] In step S508, the controller determines whether the fourth relay is closed.

[0263] If yes, proceed to step S509; otherwise, proceed to step S515.

[0264] In step S509, the second switch is closed by the controller.

[0265] The fourth detection point is powered on via the second power-on circuit.

[0266] In step S510, U2 and U5 are acquired by voltage acquisition device 3.

[0267] The voltage values ​​at the first voltage terminal of the second voltage divider circuit and the first voltage terminal of the fifth voltage divider circuit are collected by voltage acquisition device 3.

[0268] In step S511, the controller receives U2 and U5 and calculates the voltage values ​​of the fourth detection point D and the fifth detection point E.

[0269] The controller obtains the voltage value of one detection point of the outer relay, namely the voltage value of the fourth detection point D, based on the voltage value of the first voltage terminal and the voltage value of the second reference voltage terminal UVREF2 of a voltage divider circuit electrically connected to one detection point of the outer relay; and obtains the voltage value of the other detection point of the outer relay, namely the voltage value of the fifth detection point E, based on the voltage value of the first voltage terminal and the voltage value of the second reference voltage terminal UVREF2 of a voltage divider circuit electrically connected to the other detection point of the outer relay.

[0270] D: (U2-UVREF2)×(R3+R4+R14) / R4+UVREF2.

[0271] E: (U5-UVREF2)×(R9+R10+R14) / R10+UVREF2.

[0272] In step S512, the controller determines whether the voltage values ​​of the fourth detection point D and the fifth detection point E are equal.

[0273] The controller determines whether the fifth relay is closed based on whether the voltage values ​​at the detection points across the two ends of the fifth relay are equal. If yes, proceed to step S513; otherwise, proceed to step S514.

[0274] The controller determines whether (U2-UVREF2)×(R3+R4+R14) / R4+UVREF2 is equal to (U5-UVREF2)×(R9+R10+R14) / R10+UVREF2.

[0275] In step S513, it is determined that the fifth relay is closed.

[0276] In step S514, it is determined that the fifth relay is disconnected.

[0277] In step S515, the first switch is closed by the controller.

[0278] In step S516, voltage acquisition device 3 acquires U5 and U6.

[0279] The voltage values ​​at the first voltage terminals of the fifth voltage divider circuit and the sixth voltage divider circuit are collected by voltage acquisition device 3.

[0280] In step S517, the controller receives U5 and U6 and calculates the voltage values ​​of the fifth detection point E and the sixth detection point F.

[0281] The controller obtains the voltage value of one detection point of the outer relay, namely the voltage value of the fifth detection point E, based on the voltage value of the first voltage terminal and the voltage value of the second reference voltage terminal UVREF2 of a voltage divider circuit electrically connected to one detection point of the outer relay; and obtains the voltage value of the other detection point of the outer relay, namely the voltage value of the sixth detection point F, based on the voltage value of the first voltage terminal and the voltage value of the second reference voltage terminal UVREF2 of a voltage divider circuit electrically connected to the other detection point of the outer relay.

[0282] E: (U5-UVREF2)×(R9+R10+R13) / R10+UVREF2.

[0283] F: (U6-UVREF2)×(R11+R12+R13) / R12+UVREF2.

[0284] In step S518, the controller determines whether the voltage values ​​of the fifth detection point E and the sixth detection point F are equal.

[0285] The controller determines whether the fifth relay is closed based on whether the voltage values ​​at the detection points across the two ends of the fifth relay are equal. If yes, proceed to step S519; otherwise, proceed to step S520.

[0286] The controller determines whether (U5-UVREF2)×(R9+R10+R13) / R10+UVREF2 is equal to (U6-UVREF2)×(R11+R12+R13) / R12+UVREF2.

[0287] In step S519, it is determined that the fifth relay is closed.

[0288] In step S520, it is determined that the fifth relay is disconnected.

[0289] It should be noted that U1 to U6 mentioned in Figures 12 to 16 are voltage values ​​obtained by the voltage acquisition terminals of the voltage acquisition device.

[0290] Some embodiments of this disclosure also provide a battery management system 200, as shown in FIG17, which includes the above-described relay state detection circuit 100.

[0291] In summary, according to functional safety requirements, the battery management system 200 needs to identify unexpected high voltage drops or rises, and the circuit needs to avoid single-point failures. The implementation process of this disclosure is as follows: The process for identifying unexpected high voltage drops is as follows: close the third switch K3, and according to the schemes in Figures 12 and 13 above, collect the voltage of the power battery pack, the voltage between the second check point C and the fourth detection point D, and the closing status of the first relay S1 and the second relay S2. Here, the state of the second relay S2 is determined using the second voltage divider circuit and a preset formula, and the voltage between the second check point C and the fourth detection point D is calculated using the voltage of the second voltage divider circuit.

[0292] When the first relay S1 and the second relay S2 are simultaneously open (open), or the voltage between the second check point C and the fourth detection point D is not equal to the voltage between the power battery pack, the system is considered to be in a low-voltage state. When the failure of at least one of the voltage acquisition unit and the voltage divider circuit causes the failure of any one of the circuits of the first relay S1 and the second relay S2, if it is detected that either the first relay S1 or the second relay S2 is not closed, it can be determined that the high-voltage state is determined by whether the voltage between the second check point C and the fourth detection point D is equal to the voltage between the power battery pack. If they are not equal, it proves that the system has been in a low-voltage state.

[0293] This approach enables two monitoring schemes for high-voltage status, avoiding false high-voltage reports caused by circuit faults and establishing a process for identifying unexpected high-voltage drops. Similarly, to prevent erroneous high-voltage reporting, it requires simultaneous detection of the first relay S1 and the second relay S2 being closed (or stuck), and the voltage between the second checkpoint C and the fourth detection point D being equal to that of the power battery pack. Only then is high-voltage status identified, preventing erroneous system identification. Furthermore, all detection circuits are independent of each other, meeting functional safety requirements. In other words, this circuit possesses a functional safety level of C or higher, enabling monitoring of abnormal high-voltage rises or unexpected high-voltage drops.

[0294] The above are merely specific embodiments of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any changes or substitutions within the technical scope disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A relay status detection circuit, comprising: Power battery pack (1); Multiple relays (2) are connected in series between the positive and negative terminals of the power battery pack (1); each of the multiple relays (2) has a detection point at both ends; Voltage acquisition device (3); Multiple voltage divider circuits (4) are provided, wherein the first voltage terminal (401) of any one of the multiple voltage divider circuits (4) is electrically connected to the voltage acquisition terminal (U) of the voltage acquisition device (3); the second voltage terminal (402) of the voltage divider circuit (4) is electrically connected to the detection point, and the third voltage terminal (403) of the voltage divider circuit (4) is electrically connected to the reference voltage terminal; the voltage acquisition device (3) is configured to acquire the voltage value of the first voltage terminal (401) of the voltage divider circuit. as well as A controller (5) is electrically connected to the voltage acquisition unit (3). The controller (5) is configured to: receive the voltage value of the first voltage terminal (401) of the voltage divider circuit (4) acquired by the voltage acquisition unit (3), and obtain the voltage value of the detection points at both ends of the relay under test based on the voltage value of the first voltage terminal (401) of the voltage divider circuit (4) connected to the detection points at both ends of the relay under test and the voltage value of the reference voltage terminal (UVREF), and determine the state of the relay under test based on the voltage value of the detection points at both ends of the relay under test. The state of the relay under test includes the relay under test being open and the relay under test being closed; the relay under test is one of the plurality of relays (2), and at least one of the detection points at both ends of the relay under test is in an energized state.

2. The relay state detection circuit according to claim 1, wherein, The plurality of relays (2) includes at least one of the following: A first relay (S1) is provided with a first terminal connected to the positive terminal of the power battery pack (1). A first detection point (A) is provided at the first terminal of the first relay (S1), and a second detection point (C) is provided at the second terminal of the first relay (S1). as well as The second relay (S2) has its first end electrically connected to the negative terminal of the power battery pack (1); the first end of the second relay (S2) is provided with a third detection point (B), and the second end of the second relay (S2) is provided with a fourth detection point (D). The reference voltage terminal (UVREF) includes: The first reference voltage terminal (UVREF1) is electrically connected to the ground terminal of the voltage acquisition unit (3); as well as The second reference voltage terminal (UVREF2) is electrically connected to the power supply terminal of the voltage acquisition unit (3).

3. The relay state detection circuit according to claim 2, wherein, The plurality of voltage divider circuits (4) include at least one of the following: a first voltage divider circuit (41), a third voltage divider circuit (43), a fourth voltage divider circuit (44), and a second voltage divider circuit (42); The first voltage terminal of the first voltage divider circuit (41) is electrically connected to the first voltage acquisition terminal (U1) of the voltage acquisition device (3), the second voltage terminal of the first voltage divider circuit (41) is electrically connected to the second detection point (C), and the third voltage terminal of the first voltage divider circuit (41) is electrically connected to the second reference voltage terminal (UVREF2). The first voltage terminal of the second voltage divider circuit (42) is electrically connected to the second voltage acquisition terminal (U2) of the voltage acquisition device (3); the second voltage terminal of the second voltage divider circuit (42) is electrically connected to the fourth detection point (D); and the third voltage terminal of the second voltage divider circuit (42) is electrically connected to the second reference voltage terminal (UVREF2). The first voltage terminal of the third voltage divider circuit (43) is electrically connected to the third voltage acquisition terminal (U3) of the voltage acquisition device (3); the second voltage terminal of the third voltage divider circuit (43) is electrically connected to the second detection point (C); and the third voltage terminal of the third voltage divider circuit (43) is electrically connected to the first reference voltage terminal (UVREF1) and the third detection point (B). The first voltage terminal of the fourth voltage divider circuit (44) is electrically connected to the fourth voltage acquisition terminal (U4) of the voltage acquisition device (3); the second voltage terminal of the fourth voltage divider circuit (44) is electrically connected to the first detection point (A); and the third voltage terminal of the fourth voltage divider circuit (44) is electrically connected to the first reference voltage terminal (UVREF1) and the third detection point (B).

4. The relay state detection circuit according to claim 3, wherein, The first voltage divider circuit (41) includes: A first resistor (R1) is connected, with its first end electrically connected to the second detection point (C) and its second end electrically connected to the first voltage acquisition terminal (U1) of the voltage acquisition device (3); and The second resistor (R2) has its first end electrically connected to the second end of the first resistor (R1), and its second end electrically connected to the second reference voltage terminal (UVREF2). The second voltage divider circuit (42) includes: The third resistor (R3) has its first end electrically connected to the fourth detection point (D), and its second end electrically connected to the second voltage acquisition terminal (U2) of the voltage acquisition device (3); and The fourth resistor (R4) has its first end electrically connected to the second end of the third resistor (R3), and its second end electrically connected to the second reference voltage terminal (UVREF2). The third voltage divider circuit (43) includes: The fifth resistor (R5), the first end of which is electrically connected to the second detection point (C), and the second end of which is electrically connected to the third voltage acquisition terminal (U3) of the voltage acquisition device (3); and The sixth resistor (R6) has its first end electrically connected to the second end of the fifth resistor (R5), and its second end electrically connected to the first reference voltage terminal (UVREF1). The fourth voltage divider circuit (44) includes: The seventh resistor (R7) has its first end electrically connected to the first detection point (A) and its second end electrically connected to the fourth voltage acquisition terminal (U4) of the voltage acquisition device (3); and The eighth resistor (R8) has its first end electrically connected to the second end of the seventh resistor (R7), and its second end electrically connected to the first reference voltage terminal (UVREF1).

5. The relay state detection circuit according to any one of claims 2 to 4, wherein, The plurality of relays (2) further includes: a plurality of outer relays (21); the plurality of voltage divider circuits (4) further includes a voltage divider circuit connected to any one of the plurality of outer relays (21); The plurality of external relays (21) are connected in series and are connected between the first relay and the second relay; The first voltage terminal of the voltage divider circuit connected to the outer relay (21) is electrically connected to the voltage acquisition terminal of the voltage acquisition device (3), the second voltage terminal of the voltage divider circuit connected to the outer relay (21) is electrically connected to the detection point of the outer relay (21), and the third voltage terminal of the voltage divider circuit connected to the outer relay (21) is electrically connected to the second reference voltage terminal (UVREF2).

6. The relay state detection circuit according to claim 5, wherein, The plurality of outer relays (21) includes: a fourth relay (S4); the plurality of outer relays (21) further includes: at least one of a third relay (S3) and a fifth relay (S5); The first end of the third relay (S3) is electrically connected to the second end of the first relay (S1), and the second end of the third relay (S3) is provided with a fifth detection point (E); The first terminal of the fourth relay (S4) is electrically connected to the second terminal of the second relay (S2), and the second terminal of the fourth relay (S4) is provided with a sixth detection point (F); The first terminal of the fifth relay (S5) is electrically connected to the second terminal of the third relay (S3), and the second terminal of the fifth relay (S5) is electrically connected to the second terminal of the fourth relay (S4).

7. The relay state detection circuit according to claim 6, wherein, The plurality of voltage divider circuits (4) further include at least one of a fifth voltage divider circuit (45) and a sixth voltage divider circuit (46); The first voltage terminal of the fifth voltage divider circuit (45) is electrically connected to the fifth voltage acquisition terminal (U5) of the voltage acquisition device (3); the second voltage terminal of the fifth voltage divider circuit (45) is electrically connected to the fifth detection point (E); and the third voltage terminal of the fifth voltage divider circuit (45) is electrically connected to the second reference voltage terminal (UVREF2). The first voltage terminal of the sixth voltage divider circuit (46) is electrically connected to the sixth voltage acquisition terminal (U6) of the voltage acquisition device (3); the second voltage terminal of the sixth voltage divider circuit (46) is electrically connected to the sixth detection point (F); and the third voltage terminal of the sixth voltage divider circuit (46) is electrically connected to the second reference voltage terminal (UVREF2).

8. The relay state detection circuit according to claim 7, wherein, The fifth voltage divider circuit (45) includes: The ninth resistor (R9), the first end of which is electrically connected to the fifth detection point (E), and the second end of which is electrically connected to the fifth voltage acquisition terminal (U5) of the voltage acquisition device (3); and The tenth resistor (R10) has its first end electrically connected to the second end of the ninth resistor (R9), and its second end electrically connected to the second reference voltage terminal (UVREF2). The sixth voltage divider circuit (46) includes: The eleventh resistor (R11), the first end of which is electrically connected to the sixth detection point (F), and the second end of which is electrically connected to the sixth voltage acquisition terminal (U6) of the voltage acquisition device (3); and The twelfth resistor (R12) has its first end electrically connected to the second end of the eleventh resistor (R11), and its second end electrically connected to the second reference voltage terminal (UVREF2).

9. The relay status detection circuit according to any one of claims 5 to 8, further comprising: The charging gun (6) has a first output terminal electrically connected to one end of one of the plurality of external relays (21), and a second output terminal electrically connected to one end of another of the plurality of external relays (21). The charging gun (6) is configured to energize the detection points of some of the plurality of outer relays (21).

10. The relay status detection circuit according to any one of claims 1 to 9, further comprising: At least one power-on circuit (7), the first end of which is electrically connected to the positive terminal of the power battery pack (1), and the second end of which is electrically connected to the detection point between two adjacent outer relays (21); The plurality of relays (2) includes an outer relay (21), and the power-on circuit (7) is configured to power on the detection point of the outer relay (21).

11. The relay state detection circuit according to claim 10, wherein, The plurality of external relays (21) include: a third relay (S3), a fourth relay (S4), and a fifth relay (S5); The at least one power-on circuit (7) includes: a first power-on circuit (71) and a second power-on circuit (72); The first terminal of the first power-on circuit (71) is electrically connected to the positive terminal of the power battery pack (1), and the second terminal of the first power-on circuit (71) is electrically connected to the second terminal of the third relay (S3). The first power-on circuit (71) includes: The thirteenth resistor (R13), the first end of which is electrically connected to the positive terminal of the power battery pack (1); and The first switch (K1) has its first terminal electrically connected to the second terminal of the thirteenth resistor (R13), and its second terminal is electrically connected to the second terminal of the third relay (S3). The first end of the second power-on circuit (72) is electrically connected to the positive terminal of the power battery pack (1), and the second end of the second power-on circuit (72) is electrically connected to the second end of the second relay (S2). The second power-on circuit (72) includes: The fourteenth resistor (R14), the first end of which is electrically connected to the positive terminal of the power battery pack (1); and The second switch (K2) has its first terminal electrically connected to the second terminal of the fourteenth resistor (R14), and its second terminal electrically connected to the second terminal of the second relay. The controller (5) is also configured to control the opening and closing of the first switch (K1) and the second switch (K2); When the first switch (K1) is closed, the detection point connected to the first power-on circuit (71) is in a powered-on state; When the second switch (K2) is closed, the detection point connected to the second power-on circuit (72) is in a powered-on state.

12. The relay state detection circuit according to claim 11, comprising: The motor (8) has its first end electrically connected to the second end of the first relay (S1), its second end electrically connected to the second end of the third relay (S3), and its third end electrically connected to the second end of the second relay (S2).

13. A detection method for a relay state detection circuit, applied to the relay state detection circuit (100) according to any one of claims 1 to 12; wherein, The method includes: Receive the voltage value of the first voltage terminal of the voltage divider circuit (4) collected by the voltage acquisition device (3); Based on the voltage value at the first voltage terminal of the voltage divider circuit (4) connected to the detection points at both ends of the relay under test and the voltage value at the reference voltage terminal (UVREF), the voltage values ​​at the detection points at both ends of the relay under test are obtained; and The state of the relay under test is determined based on the voltage values ​​at the detection points at both ends of the relay under test. The state of the relay under test includes the relay under test being open and the relay under test being closed. The relay under test is one of the plurality of relays. At least one of the detection points at both ends of the relay under test is in the power-on state.

14. The detection method for the relay state detection circuit according to claim 13, wherein, The relay status detection circuit (100) includes multiple relays (2), including a first relay (S1); the relay to be tested is the first relay; The relay state detection circuit includes a third voltage divider circuit (43) and a fourth voltage divider circuit (44); the method includes: Receive the voltage value of the first voltage terminal of the third voltage divider circuit (43) and the voltage value of the first voltage terminal of the fourth voltage divider circuit (44) collected by the voltage acquisition unit (3); The voltage value of the second detection point (C) of the first relay (S1) is obtained based on the voltage value of the first voltage terminal of the third voltage divider circuit (43) and the voltage value of the reference voltage terminal (UVREF). Based on the voltage value at the first voltage terminal of the fourth voltage divider circuit (44) and the voltage value at the reference voltage terminal (UVREF), the voltage value at the first detection point (A) of the first relay (S1) is obtained; and The state of the first relay (S1) is determined based on the voltage values ​​at the detection points at both ends of the first relay (S1).

15. The detection method for the relay state detection circuit according to claim 13 or 14, wherein, The relay status detection circuit (100) includes a second relay (S2) among its multiple relays (2); the relay to be tested is the second relay (S2); the relay status detection circuit includes a second voltage divider circuit (42) among its multiple voltage divider circuits. Receive the voltage value of the first voltage terminal of the second voltage divider circuit (42) collected by the voltage acquisition device (3); Based on the voltage value of the first voltage terminal of the second voltage divider circuit (42) and the voltage value of the second reference voltage terminal (UVREF2), the voltage value of the fourth detection point (D) of the second relay (S2) is obtained. The voltage value at the third detection point (B) of the second relay (S2) is obtained according to the preset formula; as well as The state of the second relay (S2) is determined based on the voltage values ​​at the detection points at both ends of the second relay (S2).

16. The detection method for the relay state detection circuit according to any one of claims 13 to 15, wherein, The relay status detection circuit (100) includes multiple relays, including an outer relay (21); the relay under test is the outer relay (21); one detection point of the outer relay (21) is electrically connected to one of the multiple voltage divider circuits (4), and another detection point of the outer relay (21) is electrically connected to another of the multiple voltage divider circuits (4); the method includes: Receive the voltage value of the first voltage terminal of the voltage divider circuit (4) collected by the voltage acquisition device (3); The voltage value of a detection point of the outer relay (21) is obtained based on the voltage value of the first voltage terminal and the voltage value of the second reference voltage terminal (UVREF2) of the voltage divider circuit electrically connected to a detection point of the outer relay (21). The voltage value of the other detection point of the outer relay (21) is obtained based on the voltage value of the first voltage terminal of the other voltage divider circuit electrically connected to another detection point of the outer relay (21) and the voltage value of the second reference voltage terminal (UVREF2); and The state of the outer relay (21) is determined based on the voltage values ​​at the detection points at both ends of the outer relay (21).

17. A battery management system, comprising: The relay status detection circuit (100) according to any one of claims 1 to 12.

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