Power battery relay state diagnosis detection circuit and diagnosis method

Abstract

The invention discloses a power battery relay state diagnosis detection circuit and a diagnosis method, and relates to the technical field of electric vehicle electronic control. Comprising a first high-voltage acquisition loop, a second high-voltage acquisition loop, a control unit and a function connection module, a first end of the first high-voltage acquisition loop is connected with a high-side anode of the battery pack, a second end of the first high-voltage acquisition loop is connected with a low-side cathode of the battery pack, and a third end of the first high-voltage acquisition loop is connected with the control unit; the first end of the second high-voltage acquisition loop is connected with the second ends of the main positive relay and the pre-charging relay, the second end of the second high-voltage acquisition loop is connected with the first end of the main negative relay, the third end of the second high-voltage acquisition loop is connected with the first end of the function connection module, and the fourth end of the second high-voltage acquisition loop is connected with the control unit; the second end of the function connection module is connected with the second end of the main negative relay. The function connection module is arranged, the arrangement of a high-voltage acquisition loop is reduced, the circuit structure is simple, and the diagnosis logic is convenient.

Description

Technical Field

[0001] The present invention relates to the technical field of electric vehicle electronic control, and more specifically, to a power battery relay state diagnosis and detection circuit and a diagnosis method. Background Art

[0002] Since relays with auxiliary contacts are expensive and the false alarm rate of diagnosis through auxiliary contacts is relatively high, most enterprises choose relays without auxiliary contacts. The adhesion detection methods of relays without auxiliary contacts are similar, and the disconnection or conduction state is identified by detecting the voltages at the front and rear ends of the relay. The detection of battery high voltage and the relay adhesion detection function are usually combined. The more relays there are, the more circuits for collecting high voltage are required, and the detection circuit and diagnosis logic are more complex. The detection circuit for the relay on the high side (between the power supply and the load) is relatively simple, but the detection circuit for the relay on the low side (between the load and the ground terminal) is a difficult point. The most important thing in the design of the detection circuit for the low-side relay of the battery management system is how to raise or lower the voltage at the front end of the relay so as to judge its state by comparing the front and rear voltages. For the high-side multi-relay system detection, a general solution requires designing a high-voltage detection circuit for each high-voltage point collected or implementing it through a matrix switch. There are many detection circuits and the diagnosis logic is complex. In the prior art for the low side, an additional power supply is generally introduced to detect the voltage of the low-side circuit to realize the diagnosis of the low-side relay state. However, injecting additional voltage requires adding circuit components, resulting in increased cost and complex circuit. Another prior art uses a combination of an insulation detection circuit and a voltage division circuit (with a switch). By combining the opening and closing of the switch to obtain the front and rear voltages and comparing them with the preset voltage to judge the relay state. This method is affected by the insulation detection time and is not friendly to the real-time power-on of the vehicle. At the same time, it is greatly affected by the load X / Y capacitance and is prone to false alarms, and its reliability needs to be verified. Summary of the Invention

[0003] In view of this, the present invention provides a power battery relay state diagnosis and detection circuit and a diagnosis method to solve the problems raised in the background art and achieve simple diagnosis of the high- and low-side relay states with low cost and high reliability.

[0004] To achieve the above object, the present invention adopts the following technical solutions: On the one hand, a power battery relay state diagnosis and detection circuit is provided, including a first high-voltage acquisition circuit, a second high-voltage acquisition circuit, a control unit, and a functional connection module; wherein, the first end of the first high-voltage acquisition circuit is connected to the high-side positive electrode of the battery pack, the second end of the first high-voltage acquisition circuit is connected to the low-side negative electrode of the battery pack, and the third end of the first high-voltage acquisition circuit is connected to the control unit; the first end of the second high-voltage acquisition circuit is connected to the second ends of the main positive relay and the pre-charge relay, the second end of the second high-voltage acquisition circuit is connected to the first end of the main negative relay, the third end of the second high-voltage acquisition circuit is connected to the first end of the functional connection module, and the fourth end of the second high-voltage acquisition circuit is connected to the control unit; the second end of the functional connection module is connected to the second end of the main negative relay.

[0005] Preferably, the first high-voltage acquisition circuit includes a first voltage-dividing resistor R1, a first opto-coupler switch K1, a second voltage-dividing resistor R2, and a first acquisition module; the first end of the first voltage-dividing resistor R1 is connected to the high-side positive electrode of the battery pack and the first ends of the main positive relay and the pre-charge relay, the second end of the first voltage-dividing resistor R1 is sequentially connected to the low-side negative electrode of the battery pack through the first opto-coupler switch K1 and the second voltage-dividing resistor R2, the connection point between the first opto-coupler switch K1 and the second voltage-dividing resistor R2 is the third end of the first high-voltage acquisition circuit, and the third end of the first high-voltage acquisition circuit is connected to the control unit through the first acquisition module.

[0006] Preferably, the second high-voltage acquisition circuit includes a third voltage-dividing resistor R3, a second opto-coupler switch K2, a fourth voltage-dividing resistor R4, and a second acquisition module; the first end of the third voltage-dividing resistor R3 is the first end of the second high-voltage acquisition circuit, the second end of the third voltage-dividing resistor R3 is sequentially connected to the main negative relay through the second opto-coupler switch K2 and the fourth voltage-dividing resistor R4, the third end of the third voltage-dividing resistor R3 is connected to the first end of the functional connection module, the connection point between the second opto-coupler switch K2 and the fourth voltage-dividing resistor R4 is the third end of the second high-voltage acquisition circuit, and the third end of the second high-voltage acquisition circuit is connected to the control unit through the second acquisition module.

[0007] Preferably, the first acquisition module is used to measure the voltage of the connection node between the first opto-coupler switch K1 and the second voltage-dividing resistor R2 after the first opto-coupler switch K1 is turned on, and calculate the total voltage U1 of the battery pack according to the voltage between the first opto-coupler switch K1 and the second voltage-dividing resistor R2 based on the voltage division principle.

[0008] Preferably, a diode Z1 is further included between the functional connection module and the main negative relay. The positive electrode of the diode Z1 is connected to the second end of the functional connection module, and the negative electrode of the diode Z1 is connected to the second end of the main negative relay.

[0009] Preferably, the functional connection module is a voltage-dividing resistor or an opto-coupler switch.

[0010] On the other hand, a method for diagnosing and detecting the state of a power battery relay is provided, which uses the above-mentioned power battery relay state diagnosis and detection circuit for detection. The specific steps are as follows:

[0011] When the control unit controls the first opto-coupler switch K1, the second opto-coupler switch K2, and the functional connection module to be all turned on, and the main positive relay S1, the pre-charge relay S2, and the main negative relay S3 are all turned off, the first acquisition module acquires the voltage U1 of the PACK+ point to the ground, and the second acquisition module acquires the voltage U2 of the LINK+ point to the ground;

[0012] When U2 and U1 are in the first threshold interval, it is determined that the main positive relay S1 or the pre-charge relay S2 is turned off. When U2 and U1 are in the second threshold interval, it is determined that the main positive relay S1 or the pre-charge relay S2 is stuck or closed, and the relay is in a fault state, and the process of closing the high-voltage circuit is stopped;

[0013] The control unit controls the pre-charge relay S2 to be closed. The second acquisition module acquires the voltage U3 of the LINK+ to the ground, and the first acquisition module acquires the voltage U4 of the PACK+ to the ground;

[0014] When U3 and U4 are in the third threshold interval, it is determined that the main negative relay S3 is turned off. When U3 is in the fourth threshold interval, it is determined that the main negative relay S3 is stuck or closed, and the relay is in a fault state, and the process of closing the high-voltage circuit is stopped.

[0015] Preferably, it further includes that when the control unit controls the first opto-coupler switch K1 and the second opto-coupler switch K2 to be both turned on, and the third opto-coupler switch K3 to be turned off, and the main positive relay S1, the pre-charge relay S2, and the main negative relay S3 are all turned off, the first acquisition module acquires the voltage U1 of the PACK+ point to the ground, and the second acquisition module acquires the voltage U2 of the LINK+ point to the ground.

[0016] Through the above technical solutions, compared with the prior art, the present invention discloses a power battery relay state diagnosis and detection circuit and a diagnosis method, which have the following beneficial technical effects:

[0017] (1) A functional connection module is provided, reducing one high-voltage acquisition circuit, using fewer components, and greatly reducing costs;

[0018] (2) The influence of the high-voltage system capacitance is greatly reduced through the optocoupler switch and the unidirectional diode. The circuit structure is simple, the system cost is greatly reduced, and the diagnostic logic is simple and straightforward.

[0019] (3) The anti-interference ability of the system is enhanced, and the detection reliability of the system is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0021] Figure 1 It is the circuit structure diagram in Embodiment 1 of the present invention;

[0022] Figure 2 It is the specific circuit diagram in Embodiment 1 of the present invention;

[0023] Figure 3 It is the specific circuit diagram in Embodiment 2 of the present invention.

[0024] Among them, 1 is the first high-voltage acquisition circuit, 2 is the control unit, 3 is the second high-voltage acquisition circuit, and 4 is the functional connection module. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0026] Embodiment 1

[0027] The embodiment of the present invention discloses a power battery relay state diagnosis and detection circuit, as Figure 1As shown in the figure, it includes a first high-voltage acquisition circuit 1, a second high-voltage acquisition circuit 3, a control unit 2, and a functional connection module 4. Among them, the first end of the first high-voltage acquisition circuit 1 is connected to the high-side positive electrode of the battery pack, the second end of the first high-voltage acquisition circuit 1 is connected to the low-side negative electrode of the battery pack, and the third end of the first high-voltage acquisition circuit 1 is connected to the control unit 2. The first end of the second high-voltage acquisition circuit 3 is connected to the second ends of the main positive relay and the pre-charge relay, the second end of the second high-voltage acquisition circuit 3 is connected to the first end of the main negative relay, the third end of the second high-voltage acquisition circuit 3 is connected to the first end of the functional connection module 4, and the fourth end of the second high-voltage acquisition circuit 3 is connected to the control unit 2. The second end of the functional connection module 4 is connected to the second end of the main negative relay.

[0028] Further, as Figure 2 shown in the figure, the first high-voltage acquisition circuit 1 includes a first voltage-dividing resistor R1, a first opto-coupler switch K1, a second voltage-dividing resistor R2, and a first acquisition module. The first end of the first voltage-dividing resistor R1 is the first end of the first high-voltage acquisition circuit 1. The first end of the first voltage-dividing resistor R1 is connected to the high-side positive electrode of the battery pack and the first ends of the main positive relay S1 and the pre-charge relay S2. The second end of the first voltage-dividing resistor R1 is sequentially connected to the low-side negative electrode of the battery pack through the first opto-coupler switch K1 and the second voltage-dividing resistor R2. The second end of the second voltage-dividing resistor R2 is the second end of the first high-voltage acquisition circuit 1. The connection point between the first opto-coupler switch K1 and the second voltage-dividing resistor R2 is the third end of the first high-voltage acquisition circuit. The third end of the first high-voltage acquisition circuit is connected to the control unit through the first acquisition module.

[0029] Further, the second high-voltage acquisition circuit 3 includes a third voltage-dividing resistor R3, a second opto-coupler switch K2, a fourth voltage-dividing resistor R4, and a second acquisition module. The first end of the third voltage-dividing resistor R3 is the first end of the second high-voltage acquisition circuit 3. The second end of the third voltage-dividing resistor R3 is sequentially connected to the main negative relay S3 through the second opto-coupler switch K2 and the fourth voltage-dividing resistor R4. The third end of the third voltage-dividing resistor R3 is connected to the first end of the functional connection module 4. The connection point between the second opto-coupler switch K2 and the fourth voltage-dividing resistor R4 is the third end of the second high-voltage acquisition circuit 3. The third end of the second high-voltage acquisition circuit 3 is connected to the control unit 2 through the second acquisition module.

[0030] Further, the first acquisition module is used to measure the voltage of the connection node between the first opto-coupler switch K1 and the second voltage-dividing resistor R2 after the first opto-coupler switch K1 is turned on, and calculate the total voltage U1 of the battery pack according to the voltage between the first opto-coupler switch K1 and the second voltage-dividing resistor R2 based on the voltage division principle.

[0031] Further, a diode Z1 is also included between the functional connection module 4 and the main negative relay S3. This diode serves as a protection device for the detection circuit to prevent surge at the load end from damaging related devices of the detection circuit and can also play a voltage division role. The positive electrode of the diode Z1 is connected to the second end of the functional connection module 4, and the negative electrode of the diode Z1 is connected to the second end of the main negative relay S3. In this embodiment, the functional connection module 4 is a voltage dividing resistor, specifically Figure 2 in

[0032] the functional connection module is the fifth voltage dividing resistor R5.

[0033] On the other hand, a method for diagnosing the state of a power battery relay is provided, which uses a circuit for diagnosing the state of a power battery relay for detection. The specific steps are as follows:

[0034] S1. When the control unit controls the first opto-coupler switch K1, the second opto-coupler switch K2, and the functional connection module to be all turned on, and the main positive relay S1, the pre-charge relay S2, and the main negative relay S3 are all turned off, the first acquisition module acquires the voltage U1 of the PACK+ point with respect to the ground, and the second acquisition module acquires the voltage U2 of the LINK+ point with respect to the ground;

[0035] S2. When U2 and U1 are within the first threshold range, it is determined that the main positive relay S1 or the pre-charge relay S2 is turned off. When U2 and U1 are within the second threshold range, it is determined that the main positive relay S1 or the pre-charge relay S2 is stuck or closed, and the relay is in a fault state, and the process of closing the high-voltage circuit is stopped;

[0036] S3. The control unit controls the pre-charge relay S2 to be closed. The second acquisition module acquires the voltage U3 of the LINK+ with respect to the ground, and the first acquisition module acquires the voltage U4 of the PACK+ with respect to the ground;

[0037] S4. When U3 and U4 are within the third threshold range, it is determined that the main negative relay S3 is turned off. When U3 is within the fourth threshold range, it is determined that the main negative relay S3 is stuck or closed, and the relay is in a fault state, and the process of closing the high-voltage circuit is stopped.

[0038] Further, in step S2, the first threshold range is when U2 ≤ 5% * U1, the second threshold range is U2 ≥ 95% * U1, in step S4, the third threshold range is U3 ≥ 95% * U4, and the fourth threshold range is U3 ≤ UREF. The specific magnitude of the preset reference voltage UREF can be set according to the actual situation, and it can be set to 30% * the total voltage, or alternatively, it can also be set to 40% * the total voltage. The specific magnitude of the reference voltage is not specifically limited herein and is selected according to the specific system parameter requirements.

[0039] Embodiment 2

[0040] In this embodiment, only the setting of the functional connection module is different from that in Embodiment 1, and the rest of the connection relationships are the same. In Embodiment 2, the functional connection module 4 is set as an opto-coupler switch, as Figure 3 shown. For occasions with high requirements for high-low voltage isolation, this solution can be implemented. The first end of the third opto-coupler switch K3 is connected to the third end of the third voltage-dividing resistor R3, and the second end of the third opto-coupler switch K3 is connected to the second end of the low-side main negative relay S3.

[0041] Based on the same technical concept, the steps of the power battery relay state diagnosis and detection method in this embodiment are as follows:

[0042] S1. When the control unit controls the first opto-coupler switch K1 and the second opto-coupler switch K2 to be both turned on, and the third opto-coupler switch K3 is turned off, and the main positive relay S1, the pre-charge relay S2, and the main negative relay S3 are all turned off, the first acquisition module acquires the voltage U1 of the PACK+ point to the ground, and the second acquisition module acquires the voltage U2 of the LINK+ point to the ground;

[0043] S2. When U2 and U1 are in the first threshold range, it is determined that the main positive relay S1 or the pre-charge relay S2 is turned off. When U2 and U1 are in the second threshold range, it is determined that the main positive relay S1 or the pre-charge relay S2 is stuck or closed, and the relay is in a fault state, and the process of closing the high-voltage circuit is stopped;

[0044] S3. The control unit controls the pre-charge relay S2 to be closed, the third opto-coupler switch K3 to be closed, the second acquisition module acquires the voltage U3 of the LINK+ to the ground, and the first acquisition module acquires the voltage U4 of the PACK+ to the ground;

[0045] S4. When U3 and U4 are in the third threshold range, it is determined that the main negative relay is turned off; then the third opto-coupler switch K3 is turned off. When U3 is in the fourth threshold range, it is determined that the main negative relay S3 is stuck or closed, and the relay is in a fault state, and the process of closing the high-voltage circuit is stopped.

[0046] In the present specification, the various embodiments are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the various embodiments, reference can be made to each other. For the apparatuses disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple. For the relevant parts, reference can be made to the description in the method part.

[0047] The foregoing description of the disclosed embodiments enables those skilled in the art to practice or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A power battery relay status diagnosis detection circuit, characterized in that: It includes a first high-voltage acquisition circuit, a second high-voltage acquisition circuit, a control unit, and a functional connection module; wherein, the first end of the first high-voltage acquisition circuit is connected to the positive electrode of the high side of the battery pack, the second end of the first high-voltage acquisition circuit is connected to the negative electrode of the low side of the battery pack, and the third end of the first high-voltage acquisition circuit is connected to the control unit; the first end of the second high-voltage acquisition circuit is connected to the second ends of the main positive relay and the pre-charge relay, the second end of the second high-voltage acquisition circuit is connected to the first end of the main negative relay, the third end of the second high-voltage acquisition circuit is connected to the first end of the functional connection module, and the fourth end of the second high-voltage acquisition circuit is connected to the control unit; the second end of the functional connection module is connected to the second end of the main negative relay.

2. A power battery relay status diagnosis detection circuit according to claim 1, characterized in that: The first high-voltage acquisition circuit includes a first voltage-dividing resistor R1, a first optocoupler switch K1, a second voltage-dividing resistor R2 and a first acquisition module; the first end of the first voltage-dividing resistor R1 is connected to the positive electrode of the high side of the battery pack and the first ends of the main positive relay and the pre-charging relay, the second end of the first voltage-dividing resistor R1 is connected to the negative electrode of the low side of the battery pack through the first optocoupler switch K1 and the second voltage-dividing resistor R2 in sequence, the connection point between the first optocoupler switch K1 and the second voltage-dividing resistor R2 is the third end of the first high-voltage acquisition circuit, and the third end of the first high-voltage acquisition circuit is connected to the control unit through the first acquisition module.

3. A power battery relay status diagnosis detection circuit according to claim 1, characterized in that: The second high-voltage acquisition circuit includes a third voltage-dividing resistor R3, a second optocoupler switch K2, a fourth voltage-dividing resistor R4 and a second acquisition module; the first end of the third voltage-dividing resistor R3 is the first end of the second high-voltage acquisition circuit, the second end of the third voltage-dividing resistor R3 is connected to the main negative relay through the second optocoupler switch K2 and the fourth voltage-dividing resistor R4 in sequence, the third end of the third voltage-dividing resistor R3 is connected to the first end of the functional connection module, the connection point between the second optocoupler switch K2 and the fourth voltage-dividing resistor R4 is the third end of the second high-voltage acquisition circuit, and the third end of the second high-voltage acquisition circuit is connected to the control unit through the second acquisition module.

4. A power battery relay status diagnosis detection circuit according to claim 2, characterized in that: The first acquisition module is used to measure the voltage of the connection node between the first optocoupler switch K1 and the second voltage-dividing resistor R2 after the first optocoupler switch K1 is turned on, and the total voltage U1 of the battery pack is calculated based on the voltage division principle by converting the voltage between the first optocoupler switch K1 and the second voltage-dividing resistor R2.

5. A power battery relay status diagnosis detection circuit according to claim 1, characterized in that: A diode Z1 is further included between the function connection module and the main negative relay, wherein the anode of the diode Z1 is connected to the second end of the function connection module, and the cathode of the diode Z1 is connected to the second end of the main negative relay.

6. A power battery relay status diagnosis detection circuit according to claim 1, characterized in that: The functional connection module is a voltage divider resistor or an optical coupler switch.

7. A power battery relay status diagnosis and detection method, characterized in that: The detection is performed using a power battery relay state diagnosis detection circuit as described in any one of claims 1 to 6, and the specific steps include the following: The control unit controls the first optocoupler switch K1, the second optocoupler switch K2, and the function connection module to be turned on, and the main positive relay S1, the pre-charge relay S2, and the main negative relay S3 are all disconnected. The first acquisition module collects the voltage U1 from the PACK+ point to the ground, and the second acquisition module collects the voltage U2 from the LINK+ point to the ground; When U2 and U1 are in the first threshold interval, it is determined that the main positive relay S1 or the pre-filling relay S2 is disconnected; when U2 and U1 are in the second threshold interval, it is determined that the main positive relay S1 or the pre-filling relay S2 is adhered or closed, the relay is in a fault state, and the closing process of the high-voltage circuit is stopped; The control unit controls the pre-charging relay S2 to close, the second acquisition module acquires the voltage U3 of LINK+ to the ground, and the first acquisition module acquires the voltage U4 of PACK+ to the ground; When U3 and U4 are in the third threshold interval, it is determined that the main negative relay S3 is disconnected. When U3 is in the fourth threshold interval, it is determined that the main negative relay S3 is adhered or closed, the relay is in a fault state, and the closing process of the high-voltage circuit is stopped.

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