A main negative relay adhesion detection circuit

Abstract

This utility model relates to the field of new energy vehicle technology and discloses a main and negative relay adhesion detection circuit, including a high-voltage system, an AFE circuit, and a main and negative relay adhesion diagnostic circuit. The high-voltage system includes multiple battery modules, a main positive relay, a pre-charge relay, a pre-charge resistor, a main negative relay, a vehicle high-voltage load, and a fuse. The AFE circuit includes a power input positive terminal, a power input negative terminal, a reference power supply, and a U1 voltage acquisition port. The main and negative relay adhesion diagnostic circuit includes a voltage divider resistor I, a voltage divider resistor II, a switch, and a diode, which are connected in series. After powering on the battery management system, if the main and negative relays are adhered, the voltage at the U1 voltage acquisition port is the voltage divided by the two resistors from the reference power supply; if the main and negative relays are not adhered, the voltage at the U1 voltage acquisition port is the reference power supply voltage, thus distinguishing whether the main and negative relays are adhered.

Description

Technical Field

[0001] This utility model relates to the field of new energy vehicle technology, specifically to a main and negative relay adhesion detection circuit. Background Technology

[0002] With the rapid development of the electric vehicle industry, the importance of the high-voltage section of electric vehicles is receiving increasing attention. The normal operation of the relays in the high-voltage charging and discharging circuit directly affects the safety of the entire vehicle. Therefore, it is necessary to detect the fault status of the relays to ensure that the power battery can be supplied with high voltage or charged when the relays are in normal working condition, and to prevent the power battery from malfunctioning when the relays fail, thus eliminating unsafe factors in the high-voltage charging and discharging process.

[0003] As the power source for the entire vehicle, the power battery system's most basic high-voltage relay arrangement includes main positive relays, main negative relays, and pre-charge relays. The main purpose of high-voltage relay control is to ensure the normal power-on and power-off operation of the battery system. The high-voltage relays close to energize the vehicle when it starts and disconnect to de-energize it when the vehicle is parked and turned off.

[0004] Existing methods for detecting main and negative relay sticking include the cross-voltage acquisition method, the auxiliary contact feedback method, and the current monitoring method. The cross-voltage acquisition method compares the voltage difference across the relay. If the main and negative relays are not controlled to conduct, but a voltage is acquired at the rear of the main and negative relays, the relay is considered to be stuck. However, this circuit is prone to false voltage. The auxiliary contact feedback method uses a relay with auxiliary contacts and indirectly judges the sticking of the main contacts by detecting the status of the auxiliary contacts. However, it requires dedicated relay hardware, which increases costs, and the auxiliary contacts themselves may also fail. The current monitoring method continuously monitors the circuit current through a current sensor. If the current continues to flow after the control signal is disconnected, it is judged to be stuck. However, it may be misjudged due to leakage current or load fluctuations.

[0005] Therefore, this utility model proposes a main negative relay adhesion detection circuit to overcome the shortcomings of the prior art. Utility Model Content

[0006] The purpose of this utility model is to provide a main and negative relay adhesion detection circuit to solve the following technical problems: the cross voltage acquisition method is prone to false voltage, the auxiliary contact feedback method requires dedicated relay hardware, which increases costs, the auxiliary contact itself may also fail, and the current monitoring method is prone to misjudgment due to leakage current or load fluctuation.

[0007] The purpose of this utility model can be achieved through the following technical solution: a main negative relay adhesion detection circuit, comprising: a high voltage system, an AFE circuit, and a main negative relay adhesion diagnostic circuit, characterized in that the high voltage system comprises multiple battery modules, a main positive relay, a precharge relay, a precharge resistor, a main negative relay, a vehicle high voltage load, and a fuse. The AFE circuit includes a positive power input terminal, a negative power input terminal, a reference power supply, and a U1 voltage acquisition port; The main negative relay adhesion diagnostic circuit includes voltage divider resistor one, voltage divider resistor two, a switch, and a diode; The voltage divider resistor one, the voltage divider resistor two, the switch, and the diode are connected in series in sequence. One end of the voltage divider resistor one is connected to the reference power supply, and the negative terminal of the diode is connected to one end of the main negative relay.

[0008] As a preferred embodiment of this utility model: the positive power input terminal and the negative power input terminal are respectively connected to the positive and negative terminals of the lowest series module of the high voltage system.

[0009] As a preferred embodiment of this utility model: multiple battery modules and the fuse are connected in series to form a high-voltage system, and one end of the main positive relay and the precharge relay are both connected to the positive terminal of the battery modules connected in series. The high-voltage load includes a capacitor and a drive motor. The other end of the pre-charge relay is connected in series with the pre-charge resistor, then connected in parallel with one end of the main positive relay, the capacitor, and the drive motor, and finally connected to the other end of the main positive relay.

[0010] As a preferred embodiment of this utility model: one end of the main negative relay is connected to the negative terminal of the battery module connected in series, and the other end of the main negative relay is connected to the other end of the capacitor and the drive motor connected in parallel, and is connected to the negative terminal of the diode in the main negative relay adhesion diagnostic circuit.

[0011] As a preferred embodiment of this utility model: the reference power supply is connected to one end of the voltage divider resistor in the main negative relay adhesion diagnostic circuit.

[0012] As a preferred embodiment of this utility model: the U1 voltage acquisition port is connected to the main negative relay adhesion diagnosis circuit.

[0013] The beneficial effects of this utility model are: This invention sets up a reference power supply with the negative terminal of the PACK as the reference ground. A voltage divider circuit is formed by voltage divider resistors 1 and 2 and the negative terminal. The voltage at the sampling point U1 is the voltage after the reference power supply is divided. After the battery management system is powered on, if the main negative relay is stuck, the voltage at the U1 voltage sampling port is the voltage divided by the two resistors of the reference power supply. When the main negative relay is not stuck, the voltage at the U1 voltage sampling port is the reference power supply voltage. In this way, the sticking of the main negative relay can be distinguished by the different sampling voltages at the U1 voltage sampling port. This circuit is simple, does not require isolation, is low in cost, and has reliable detection. Attached Figure Description

[0014] The present invention will be further described below with reference to the accompanying drawings.

[0015] Figure 1 This is the circuit diagram of this utility model.

[0016] Figure descriptions: 1. High-voltage system; 2. AFE circuit; 3. Main negative relay adhesion diagnostic circuit; S1, switch; S2, main positive relay; S3, pre-charge relay; S4, main negative relay; C1, high-voltage load; C2, capacitor; R1, voltage divider resistor one; R2, voltage divider resistor two; R3, pre-charge resistor; D1, diode; F, fuse; M, drive motor; VBAT, positive power input; GND, negative power input; Vcom, reference power supply; GPIO1, U1 voltage acquisition port. Detailed Implementation

[0017] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0018] Please see Figure 1 As shown, this utility model is a main negative relay adhesion detection circuit, including a high voltage system 1, an AFE circuit 2, and a main negative relay adhesion diagnosis circuit 3. The high voltage system 1 includes multiple battery modules, a main positive relay S2, a precharge relay S3, a precharge resistor R3, a main negative relay S4, and a vehicle high voltage load C1. Multiple battery modules are connected in series to form a high-voltage system 1. One end of the main positive relay S2 and the pre-charge relay S3 are both connected to the positive terminal of the series-connected battery modules. The high-voltage load C1 includes capacitor C2 and drive motor M. The other end of the pre-charge relay S3 is connected in series with the pre-charge resistor R3, and then connected in parallel with one end of the main positive relay S2, capacitor C2, and drive motor M. One end of the main negative relay S4 is connected to the negative terminal of the series-connected battery modules. The other end of the main negative relay S4 is connected in parallel with capacitor C2 and drive motor M, and then connected to the negative terminal of diode D1 in the main negative relay adhesion diagnostic circuit 3.

[0019] Specifically, the high-voltage load C1 is equivalent to the motor controller in an electric vehicle. When the motor controller is working, the current is large, which will directly lower the voltage of the battery module. Therefore, there is a supercapacitor C2 inside it. When the supercapacitor C2 is de-energized, it is actually in a short-circuit state. If the high voltage is applied and the main and auxiliary relays S4 and the main positive relay S2 are closed directly without pre-charging, it may cause electric shock and burnout.

[0020] The main positive relay S2, precharge relay S3, and precharge resistor R3 form a precharge circuit. The normal power-on logic of the vehicle is to first close the main negative relay S4, and then close the precharge relay S3. At this time, the current will pass through the precharge relay S3 and the precharge resistor R3. Because of the presence of the precharge resistor R3, the current will be reduced, so that the external circuit can stably withstand the high voltage, thereby completing the precharge of the high-voltage load C1. When the high-voltage load C1 is fully charged, its voltage will increase. At this time, it is at a high potential, and the side coming from the battery module is also at a high potential. Under these circumstances, closing the main positive relay S2 will not generate an electric spark because there is no voltage difference, reducing the risk of arcing in the high-voltage system, avoiding instantaneous high current directly impacting the components, and preventing failures caused by overheating or damage.

[0021] AFE circuit 2 includes power input positive terminal VBAT, power input negative terminal GND, reference power supply Vcom, and U1 voltage acquisition port GPIO1; The positive power input VBAT and the negative power input GND are connected to the positive and negative terminals of the lowest series module of the high voltage system 1, respectively. The reference power supply Vcom is connected to one end of the voltage divider resistor R1 in the main negative relay adhesion diagnostic circuit 3. The voltage acquisition port GPIO1 of U1 is connected to the main negative relay adhesion diagnostic circuit 3.

[0022] Specifically, the positive power input VBAT and the negative power input GND are connected to the positive and negative terminals of the lowest series module of the high voltage system 1, respectively, to provide power to the AFE circuit 2. The reference power supply Vcom is generated by internal or external circuitry of the AFE circuit 2 chip and is used to provide the pull-up voltage for the main negative relay adhesion diagnostic circuit 3. The reference power supply Vcom is connected to one end of R1 in the main negative relay adhesion diagnostic circuit 3; The U1 voltage acquisition port GPIO1 is connected to the main negative relay adhesion diagnostic circuit 3 to acquire the voltage at point U1. This circuit does not require an isolation circuit, which is especially convenient for integrated battery management systems.

[0023] The main negative relay adhesion diagnostic circuit 3 includes voltage divider resistor R1, voltage divider resistor R2, switch S1, and diode D1; Voltage divider resistor R1, voltage divider resistor R2, switch S1, and diode D1 are connected in series. One end of voltage divider resistor R1 is connected to the reference power supply Vcom, and the cathode of diode D1 is connected to one end of the main negative relay S4.

[0024] Specifically, in the main and negative relay adhesion diagnostic circuit 3, switch S1 is closed when the main and negative relay S4 adhesion test begins. When the diagnostic process is completed and the main and negative relay S4 is closed, switch S1 is opened, which disconnects the main and negative relay adhesion diagnostic circuit 3 from the high voltage system 1, preventing abnormal high voltage from entering the AFE circuit 2 through the main and negative relay adhesion diagnostic circuit 3, thereby protecting the AFE circuit 2 and preventing it from being damaged. In the main negative relay adhesion diagnostic circuit 3, diode D1 is used to withstand reverse voltage when the power battery is in a high-voltage connection state and the high-voltage load is in operation. If the main negative relay S4 suddenly disconnects due to a fault, and the high-voltage load is not turned off or is delayed in turning off, the power battery voltage will form a loop through the main positive relay S2, the vehicle high-voltage load C1, the main negative relay adhesion diagnostic circuit 3, the AFE circuit 2, and the PACK negative terminal. This will cause high voltage to be generated at both ends of the reference power supply Vcom in the AFE circuit 2, resulting in damage to the chip in the AFE circuit 2. Therefore, diode D1 is added to withstand the reverse voltage.

[0025] The working principle of this utility model is as follows: After the battery management system is powered on, the switch S1 is closed, and the main negative relay S4 is activated to detect adhesion. By setting a reference power supply Vcom with the negative terminal of the PACK as the reference ground, and using the voltage difference between voltage divider resistors R1 and R2 at sampling point U1, it is determined whether the main negative relay S4 is stuck, as follows: When the main negative relay S4 is not connected: the reference power supply Vcom cannot be grounded through the voltage divider resistor R2, so that the voltage of GPIO1 at the U1 voltage acquisition port is the voltage of the reference power supply Vcom itself (at this time, the circuit does not form a voltage divider loop). When the main negative relay S4 is stuck: the reference power supply Vcom forms a voltage divider circuit with the negative terminal of PACK through voltage divider resistor 1 R1 and voltage divider resistor 2 R2: the voltage of U1 voltage acquisition port GPIO1 is the voltage value of the reference power supply Vcom after being divided by voltage divider resistor 1 R1 and voltage divider resistor 2 R2, which is lower than the reference power supply Vcom voltage.

[0026] After the diagnosis is completed, switch S1 is disconnected, the main negative relay S4 closes normally, and high voltage system 1 is put into operation.

[0027] The above description details one embodiment of the present utility model, but it is merely a preferred embodiment and should not be construed as limiting the scope of the present utility model. All equivalent variations and improvements made within the scope of the present utility model application should still fall within the patent coverage of the present utility model.

Claims

1. A main negative relay sticking detection circuit, comprising a high-voltage system (1), an AFE circuit (2), a main negative relay sticking diagnosis circuit (3), characterized in that, The high-voltage system (1) includes multiple battery modules, a main positive relay (S2), a pre-charge relay (S3), a pre-charge resistor (R3), a main negative relay (S4), a vehicle high-voltage load (C1), and a fuse (F). The AFE circuit (2) includes a positive power input terminal (VBAT), a negative power input terminal (GND), a reference power supply (Vcom), and a U1 voltage acquisition port (GPIO1). The main negative relay adhesion diagnostic circuit (3) includes voltage divider resistor one (R1), voltage divider resistor two (R2), switch (S1), and diode (D1). The voltage divider resistor one (R1), the voltage divider resistor two (R2), the switch (S1), and the diode (D1) are connected in series. One end of the voltage divider resistor one (R1) is connected to the reference power supply (Vcom), and the negative terminal of the diode (D1) is connected to one end of the main negative relay (S4).

2. The main negative relay sticking detection circuit according to claim 1, characterized in that, The positive power input terminal (VBAT) and the negative power input terminal (GND) are respectively connected to the positive and negative terminals of the lowest series module of the high voltage system (1).

3. The main negative relay sticking detection circuit according to claim 1, characterized in that, Multiple battery modules and the fuse (F) are connected in series to form a high-voltage system (1), and one end of the main positive relay (S2) and the precharge relay (S3) are both connected to the positive terminal of the battery modules connected in series. The high-voltage load (C1) includes a capacitor (C2) and a drive motor (M). The other end of the pre-charge relay (S3) is connected in series with the pre-charge resistor (R3), and then connected in parallel with one end of the main positive relay (S2), the capacitor (C2), and the drive motor (M).

4. The main negative relay sticking detection circuit according to claim 3, characterized in that, One end of the main negative relay (S4) is connected to the negative terminal of the battery module connected in series. The other end of the main negative relay (S4) is connected in parallel with the capacitor (C2) and the drive motor (M) and then connected to the negative terminal of the diode (D1) in the main negative relay adhesion diagnostic circuit (3).

5. The main negative relay sticking detection circuit according to claim 2, wherein The reference power supply (Vcom) is connected to one end of the voltage divider resistor (R1) in the main negative relay adhesion diagnostic circuit (3).

6. The main negative relay sticking detection circuit according to claim 2, characterized in that, The U1 voltage acquisition port (GPIO1) is connected to the main negative relay adhesion diagnosis circuit (3).

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