Power battery pre-charging control circuit with protection function and automobile

Abstract

The utility model discloses a power battery pre-charging control circuit with a protection function and an automobile, the control circuit comprises a pre-charging resistor R1, a pre-charging relay K3 and a control unit used for controlling the pre-charging relay K3, and the pre-charging resistor R1 and the pre-charging relay K3 are connected in series to form a main pre-charging loop; the circuit is characterized in that a temperature sensor T1 is arranged on the pre-charging resistor R1, and the output end of the temperature sensor T1 is connected to the control unit; the output end of the control unit is connected to the pre-charging relay K1 and is used for controlling the opening and closing of the pre-charging relay K3; the output end of the control unit is connected to the reminding module and used for sending out a pre-charging temperature reminding signal. The pre-charging relay has the advantages that the pre-charging resistor temperature sensor is added, the state of the pre-charging relay can be monitored at any time, the pre-charging relay is prohibited from working under the condition of abnormal temperature, the stability of the pre-charging resistor is ensured, and the failure risk of the pre-charging resistor is reduced.

Description

Technical Field

[0001] The utility model relates to the field of new energy vehicle charging, and particularly relates to a pre-charge control circuit and an automobile for a power battery with a protection function. Background Art

[0002] Currently, in the drive system of an electric vehicle, the power battery is generally connected to the motor controller, and there is a capacitor with a relatively large capacity (generally 500uF - 2000uF) in the high-voltage component controller. If the capacitor is in a zero state before power-on, that is, there is no energy in the capacitor, then at the moment when the circuit is closed, it is equivalent to a direct short circuit, and the current is extremely large. If such a large current is not limited, it will cause huge impacts and damage to the battery and the relay. Therefore, a pre-charge circuit must be added to the power supply system of the electric vehicle to reduce the inrush current during power-on and protect the motor controller, the battery, and the main relay.

[0003] The pre-charge circuit of the prior art is as Figure 1 shown. The pre-charge circuit consists of a pre-charge relay and a pre-charge resistor. The pre-charge relay and the pre-charge resistor are connected in series and then connected in parallel across the two ends of the positive relay of the battery module. Its control method is to judge the voltage during pre-charging. Before pre-charging starts, the pre-charge relay and the main negative relay are closed to start pre-charging. When the pre-charge voltage reaches more than 95% of the battery voltage, the main positive relay is closed to complete pre-charging. During the pre-charge process, the pre-charge time and the pre-charge current are generally limited to protect the pre-charge resistor. If the pre-charge current or the pre-charge time is greater than the set threshold, the current pre-charge process will be terminated after a period of time when this current is detected, and the next pre-charge request will be executed again. The problems of this control method are as follows:

[0004] 1. If the load has a short circuit or a small resistive load due to a fault, such as the capacitor being broken down, etc., it will cause UC to never rise during the pre-charge process. At this time, the current is too large, the heat generated by the pre-charge resistor increases, the resistor will be burned out, and at the same time, the pre-charge process fails, the main relay cannot be turned on, and the vehicle high voltage cannot work properly;

[0005] 2. If repeated pre-charging is carried out again under certain specific circumstances after the pre-charge fails, it will also cause the temperature of the pre-charge resistor to continuously increase, resulting in the resistor being fused and damaged. At the same time, the pre-charge process fails, the main relay cannot be turned on, and the vehicle high voltage cannot work properly. Content of the Utility Model

[0006] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a pre-charge control circuit and an automobile for a power battery with a protection function, so as to realize a pre-charge circuit with a protection function and ensure the reliable and stable operation of the pre-charge circuit.

[0007] To achieve the above object, the technical solution adopted by the present utility model is as follows: A pre-charge control circuit for a power battery with a protection function, the control circuit includes a pre-charge resistor R1, a pre-charge relay K3, and a control unit for controlling the pre-charge relay K3. The pre-charge resistor R1 and the pre-charge relay K3 are connected in series to form a main pre-charge circuit; a temperature sensor T1 is provided on the pre-charge resistor R1, and its output terminal is connected to the control unit; the output terminal of the control unit is connected to the pre-charge relay K1 for controlling the opening and closing of the pre-charge relay K3; the output terminal of the control unit is connected to a reminder module for sending a pre-charge temperature reminder signal.

[0008] The reminder module includes an in-vehicle human-machine interaction module, and the reminder is sent through the in-vehicle human-machine interaction module.

[0009] The control unit is a battery management system BMS.

[0010] The pre-charge control circuit further includes a relay K1 and a resistor R2. The relay K1 and the resistor R2 are connected in series and then connected in parallel across both ends of the main pre-charge circuit; the output terminal of the control unit is connected to the relay K1 for driving the opening and closing of the relay K1.

[0011] A temperature sensor T2 is provided on the resistor R2, and the output terminal of the temperature sensor T1 is connected to the control unit.

[0012] A current-limiting resistor R3 is connected between the main pre-charge circuit and the positive electrode of the power battery, and a relay K4 is connected in parallel across both ends of the current-limiting resistor R3; the output terminal of the control unit is connected to the relay K4 for controlling its opening and closing state.

[0013] The control circuit further includes a current sensor, which is used to collect the current signal during the operation of the pre-charge circuit, and its output terminal is connected to the control unit.

[0014] A new energy electric vehicle includes the pre-charge control circuit described above.

[0015] The advantages of the present utility model are as follows: A pre-charge resistor temperature sensor is added, which can monitor the state of the pre-charge relay at any time, prohibit operation in case of abnormal temperature, ensure the stability of the pre-charge resistor, and reduce the risk of its failure; A standby circuit is provided, which can greatly improve the stability of the pre-charge circuit and avoid the risk of being unable to charge or discharge at high voltage due to the inoperability of the pre-charge circuit; The circuit structure is simple, only adding basic components such as relays, resistors, and temperature sensors on the basis of the original pre-charge circuit, with low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The following briefly describes the content expressed in each drawing of the present invention specification and the marks in the drawings:

[0017] Figure 1 is the schematic diagram of the pre-charge circuit in the prior art;

[0018] Figure 2 is the schematic diagram of the present invention with temperature monitoring added;

[0019] Figure 3 is the structural schematic diagram of the pre-charge circuit of the present invention.

[0020] The markings in the above figures are: 1. Temperature sensor corresponding to the pre-charge resistor R1; 2. Temperature sensor corresponding to the pre-charge resistor R2. Specific embodiments

[0021] The following further describes in detail the specific embodiments of the present invention by describing the optimal embodiments with reference to the accompanying drawings.

[0022] This solution mainly redesigns the defects existing in the pre-charge circuit of the prior art to implement a new pre-charge control circuit with protection function and redundant replacement function, avoiding the potential safety hazards of the pre-charge circuit and defects such as the inability to complete pre-charge caused by pre-charge circuit failures. The specific solution is introduced as follows:

[0023] Embodiment 1:

[0024] As Figure 2 shown, a power battery pre-charge control circuit with a protection function, the control circuit includes a pre-charge resistor R1, a pre-charge relay K3, and a control unit for controlling the pre-charge relay K3. The pre-charge resistor R1 and the pre-charge relay K3 are connected in series to form a main pre-charge circuit; a temperature sensor T1 is provided on the pre-charge resistor R1, and its output end is connected to the control unit; the output end of the control unit is connected to the pre-charge relay K1 for controlling the opening and closing of the pre-charge relay K3; the output end of the control unit is connected to a reminder module for sending a pre-charge temperature reminder signal.

[0025] The pre-charge relay K3 and the pre-charge resistor R1 are connected in series to form the main pre-charge circuit. One end of the main pre-charge circuit is connected to the positive electrode of the battery module, and the other end is connected to the circuit between the positive electrode relay (main positive relay) of the battery module and the high-voltage electrical appliance. A temperature sensor T1 is provided on the pre-charge resistor R1. The temperature sensor T1 can be a surface-mounted temperature sensor, which can collect the temperature data of the pre-charge resistor R1. The temperature data is sent to the control unit. The control unit used is the battery management system BMS, that is, the battery management system BMS or its control unit BCU is used to realize the monitoring and control of the temperature. The output end of the BMS is connected to the relay K3, which is used for the control of pre-charging and the disconnection control of the pre-charge relay K3 when the temperature is abnormal, etc. The output end of the control unit is connected to the reminder module, which is used to send a reminder signal through the reminder module when the pre-charge temperature is abnormal. The reminder module includes an in-vehicle human-machine interaction module, and the reminder is sent through the in-vehicle human-machine interaction module. The human-machine interaction module includes in-vehicle components such as an in-vehicle instrument and an in-vehicle display screen.

[0026] Its working principle is as follows: A temperature sensor is arranged on the surface of the pre-charge resistor to monitor the temperature of the pre-charge resistor. The temperature controller is connected to the BMS controller, and the BMS monitors the surface temperature of the pre-charge resistor. At the beginning of pre-charging, the pre-charge relay and the main negative relay are closed successively, and the battery module starts to discharge and pre-charge the pre-charge capacitor. During the whole process, the BMS will monitor the temperature of the pre-charge relay at any time to determine its stability. When the surface temperature of the pre-charge resistor exceeds the set threshold value, the BMS immediately controls the pre-charge relay to disconnect and stop pre-charging, and reports the pre-charge failure and the over-high temperature of the pre-charge resistor, which plays a role in protecting the pre-charge relay and high-voltage safety, and prompts the pre-charge failure situation of the whole vehicle. When the temperature of the pre-charge relay drops to a safe value, the BMS allows the pre-charge relay to be closed for the next pre-charge. The pre-charge circuit scheme in the above-mentioned Embodiment 1 solves the problem that when the existing battery is pre-charged, if there is an external short circuit or continuous pre-charging, the temperature of the pre-charge resistor rises and burns out. It avoids the pre-charge relay working at an abnormal temperature and increases the service life. Moreover, in terms of logic setting, a safety logic can be further designed that when there are more than 5 consecutive pre-charge failures, the BMS will prohibit the battery module from performing high-voltage pre-charging and report the continuous pre-charge failure fault. This fault needs to be actively cleared by a diagnostic instrument before the high voltage can be pre-charged again. When the battery system has a continuous pre-charge failure fault, it indicates that there is an abnormal situation in the vehicle high-voltage system, and it needs to be detected and repaired at a repair shop. After confirmation, the high voltage can be continued to be applied, which protects the vehicle high-voltage safety and avoids damaging more high-voltage devices.

[0027] Embodiment 2:

[0028] Based on Embodiment 1, this embodiment adds a redundant circuit. The redundant circuit includes a relay K1, a resistor R2, and a temperature sensor provided on the resistor R2. The relay K1 and the resistor R2 are connected in series and then connected in parallel across both ends of the main pre-charge circuit. The main pre-charge circuit refers to the circuit formed by the series connection of the resistor R1 and K3. The output end of the control unit is connected to the relay K1 and is used to drive the relay K1 to open and close. A temperature sensor T2 is provided on the resistor R2, and the output end of the temperature sensor T1 is connected to the control unit. The temperature sensor T2 uses a surface-mounted temperature sensor.

[0029] Its working principle is as follows: After the temperature sensor T1 detects that the temperature of the resistor R1 is abnormal, the control unit controls the relay K3 to open, and at the same time controls the relay K1 to close, so as to switch the pre-charge circuit from the main pre-charge circuit to the standby redundant pre-charge circuit, thus ensuring the sustainable operation of the pre-charge circuit and avoiding the risk that the vehicle becomes unavailable due to the immediate stop of pre-charging after the temperature of the pre-charge circuit is abnormal, which affects the use experience. When switching to the standby redundant pre-charge circuit for pre-charging, K1 is closed. At this time, the working state of the monitoring temperature sensor T2 is monitored, and the temperature of the resistor R2 is obtained. Based on the temperature of the resistor R2, it is judged whether the redundant backup pre-charge circuit is normal. If it is normal, then K1 is disconnected after the pre-charging is completed, and the main positive relay K2 is closed; if the temperature detection of R2 also shows an abnormality greater than the temperature threshold, then K1 is disconnected.

[0030] In another preferred embodiment, the main pre-charge circuit and the positive pole of the power battery are connected through a current-limiting resistor R3, and a relay K4 is arranged in parallel across both ends of the current-limiting resistor R3. The output end of the control unit is connected to the relay K4 and is used to control its opening and closing states. The current sensor is used to collect the current signal during the operation of the pre-charge circuit, and its output end is connected to the control unit. The current sensor uses methods such as mutual inductors or resistor voltage division or sampling resistors to obtain the current of the pre-charge circuit. The setting point can be on the circuit between the resistor R3 and the positive pole of the battery module to monitor its current. Because of the abnormal increase in current resulting in the abnormal temperature of the resistor R1 or R2, after the temperature is abnormal, the resistor R3 can be introduced into the pre-storage circuit to increase the resistance and reduce the circuit current, thereby reducing the heat generation of the pre-charge resistor.

[0031] Its working principle is as follows: When the temperature of the main pre-charging circuit R1 is abnormal or when the temperature of the resistor R2 in the redundant backup pre-charging circuit is abnormal, the resistor R3 is activated to intervene in the pre-charging circuit. Under normal circumstances, the relay K4 is closed. When the resistor R3 needs to intervene, the relay K4 is controlled to open, then the resistor R3 is connected to the pre-charging circuit, reducing the current in the entire pre-charging circuit, thereby reducing the heat generation of R1 or R2 and improving the safety and reliability of the pre-charging resistor. When the pre-charging circuit is working normally, K4 is closed; when the temperature of the main pre-charging circuit R1 is abnormal or when the temperature of the resistor R2 in the redundant backup pre-charging circuit is abnormal, the relay K4 is controlled to open.

[0032] This application also provides a new energy electric vehicle, which includes the pre-charging control circuit in the above embodiment. Therefore, this vehicle also has all the advantages and features of this pre-charging control circuit, that is, a pre-charging resistor temperature sensor is added, which can monitor the status of the pre-charging relay at any time and prohibits operation in case of abnormal temperature, ensuring the stability of the pre-charging resistor and reducing the risk of its failure; a backup circuit is provided, which can greatly improve the stability of the pre-charging circuit and avoid the risk of being unable to charge or discharge high voltage due to the inoperability of the pre-charging circuit; the circuit structure is simple, only adding basic components such as relays, resistors, and temperature sensors on the basis of the original pre-charging circuit, with low cost.

[0033] Obviously, the specific implementation of the present invention is not limited by the above methods. As long as various non-substantive improvements are made by adopting the method concept and technical solution of the present invention, they are all within the protection scope of the present invention.

Claims

1. A pre-charge control circuit for a power battery with a protection function, the control circuit includes a pre-charge resistor R1, a pre-charge relay K3, and a control unit for controlling the pre-charge relay K3. The pre-charge resistor R1 and the pre-charge relay K3 are connected in series to form a main pre-charge loop; it is characterized in that: A temperature sensor T1 is provided on the pre-charge resistor R1, and its output terminal is connected to the control unit; the output terminal of the control unit is connected to the pre-charge relay K1 for controlling the opening and closing of the pre-charge relay K3; the output terminal of the control unit is connected to the reminder module for sending a pre-charge temperature reminder signal.

2. The pre-charge control circuit for a power battery with a protection function according to claim 1, wherein: The reminder module includes an in-vehicle human-machine interaction module, and the reminder is sent through the in-vehicle human-machine interaction module.

3. The pre-charge control circuit for a power battery with a protection function according to claim 1, characterized in that: The control unit is a battery management system BMS.

4. The pre-charge control circuit for a power battery with a protection function according to any one of claims 1-3, characterized in that: The pre-charge control circuit further includes a relay K1 and a resistor R2. The relay K1 and the resistor R2 are connected in series and then connected in parallel across both ends of the main pre-charge circuit; the output terminal of the control unit is connected to the relay K1 for driving the opening and closing of the relay K1.

5. The pre-charge control circuit for a power battery with a protection function according to claim 4, characterized in that: A temperature sensor T2 is provided on the resistor R2, and the output terminal of the temperature sensor T1 is connected to the control unit.

6. The pre-charge control circuit for power battery with protection function according to claim 4, characterized in that: A current-limiting resistor R3 is connected between the main pre-charge circuit and the positive electrode of the power battery, and a relay K4 is provided in parallel across both ends of the current-limiting resistor R3; the output terminal of the control unit is connected to the relay K4 for controlling its opening and closing state.

7. The pre-charge control circuit for a power battery with a protection function according to claim 4, characterized in that: The control circuit further includes a current sensor for collecting the current signal during the operation of the pre-charge circuit, and its output terminal is connected to the control unit.

8. A vehicle, characterized in that: The vehicle includes the pre-charge control circuit according to any one of claims 1-7.

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