CN-115771429-B - Pre-charging circuit, control method thereof, battery management system and electric automobile

CN115771429BCN 115771429 BCN115771429 BCN 115771429BCN-115771429-B

Abstract

The invention discloses a precharge circuit and a control method thereof, a battery management system and an electric automobile, wherein the circuit comprises a capacitor; the device comprises a power battery, a pre-charging inductor, a pre-charging switch, a switch control module and a switch control module, wherein the positive electrode of the power battery is connected with the first end of a capacitor, the first end of the pre-charging inductor is connected with the first end of the capacitor, the second end of the pre-charging inductor is connected with the second end of the capacitor, the pre-charging switch is connected in series between the negative electrode of the power battery and the first end of the pre-charging inductor, the input end of the switch control module is connected with the negative electrode of the power battery, the output end of the switch control module is connected with the pre-charging switch and is used for acquiring a circuit signal in a pre-charging circuit, comparing the circuit signal with a reference signal to obtain a voltage value comparison result, and controlling the on-off of the pre-charging switch according to the voltage value comparison result and a clock signal. According to the embodiment provided by the invention, the precharge efficiency, the safety and the energy conservation of the battery system can be improved.

Inventors

OUYANG WENBIN
XIONG BENBO

Assignees

欣旺达电动汽车电池有限公司

Dates

Publication Date: 20260508
Application Date: 20221209

Claims (10)

1. A precharge circuit, comprising: A capacitor; The positive electrode of the power battery is connected with the first end of the capacitor; a pre-charge inductor, wherein a first end of the pre-charge inductor is connected with a first end of the capacitor, and a second end of the pre-charge inductor is connected with a second end of the capacitor; the pre-charging switch is connected in series between the negative electrode of the power battery and the first end of the pre-charging inductor; The power battery control device comprises a power battery, a switch control module, a power battery, a voltage control module and a control module, wherein the input end of the switch control module is connected with the negative electrode of the power battery, the output end of the switch control module is connected with the pre-charging switch, the switch control module is used for acquiring a circuit signal in the pre-charging circuit, comparing the circuit signal with a reference signal to obtain a voltage value comparison result, controlling the on-off of the pre-charging switch according to the voltage value comparison result and a clock signal, the reference signal is output by a reference signal source in the switch control module, the voltage value of the reference signal is the maximum voltage threshold allowed to pass through in the pre-charging circuit, and when the voltage value comparison result is that the voltage value of the circuit signal is smaller than the voltage threshold of the reference signal and the clock signal is at a low level, the pre-charging switch is controlled to be turned on to form a first current loop which can be pre-charged by the power battery, and when the voltage value comparison result is that the voltage value of the circuit signal is larger than the voltage threshold of the reference signal, the pre-charging switch is controlled to be turned off.
2. The precharge circuit of claim 1, wherein the switch control module comprises: the signal detection amplifying module is connected in series between the negative electrode of the power battery and the pre-charging switch and is used for acquiring the circuit signal, amplifying the circuit signal and outputting an amplified signal; The non-inverting input end of the comparator is connected with the output end of the signal detection amplifying module, the inverting input end of the comparator is connected with a reference signal source and is used for receiving and comparing the amplified signal with the reference signal and outputting a voltage value comparison result; And the two logic input ends of the NOR logic module are respectively connected with the output end of the comparator and the output end of the clock generation module, and the output end of the NOR logic module is connected with the pre-charging switch and is used for controlling the on-off of the pre-charging switch according to the voltage value comparison result and the clock signal.
3. The pre-charge circuit of claim 1 further comprising a battery pack master negative switch connected between a negative electrode of the power battery and a second end of the capacitor.
4. The precharge circuit of claim 1 further comprising a first freewheel protection module connected between the first end of the precharge inductor and the first end of the capacitor, the first freewheel protection module operable to freewheel a first current flowing from the first end of the precharge inductor to the first end of the capacitor.
5. The pre-charge circuit of claim 4, further comprising a second freewheel protection module coupled between the pre-charge switch and the first end of the pre-charge inductor, the second freewheel protection module operable to freewheel a second current flowing from the first end of the pre-charge inductor to the pre-charge switch.
6. The precharge circuit of claim 2 wherein said signal sense amplification module comprises a current sense resistor connected in series between a negative electrode of said power cell and said precharge switch and a signal amplifier connected in parallel with said current sense resistor.
7. A control method of a precharge circuit, applied to the precharge circuit of claim 1, comprising: acquiring a circuit signal in the pre-charging circuit; comparing the circuit signal with a reference signal to obtain a voltage value comparison result; And controlling the on-off of the pre-charging switch according to a voltage value comparison result and a clock signal, wherein the pre-charging switch is controlled to be turned on to form a first current loop for pre-charging the capacitor by releasing energy of the power battery under the condition that the voltage value of the circuit signal is smaller than the voltage threshold of the reference signal and the clock signal is at a low level, and the pre-charging switch is controlled to be turned off to form a second current loop for pre-charging the capacitor by pre-charging inductive energy release under the condition that the voltage value of the circuit signal is larger than the voltage threshold of the reference signal.
8. The method of claim 7, further comprising a battery pack master negative switch coupled between the negative electrode of the power battery and the second terminal of the capacitor, the method further comprising: And under the condition that the voltage values at the two ends of the capacitor are equal to the voltage value of the power battery, closing the main negative switch of the battery pack to finish the active pre-charging treatment.
9. A battery management system, comprising a precharge circuit according to any one of claims 1 to 6.
10. An electric vehicle comprising the battery management system according to claim 9.

Description

Pre-charging circuit, control method thereof, battery management system and electric automobile Technical Field The present invention relates to the field of charging technologies, and in particular, to a precharge circuit, a control method thereof, a battery management system, and an electric vehicle. Background With the vigorous development of new energy electric vehicles, all manufacturers pay more attention to the safety performance and the energy-saving performance of the battery system of the electric vehicle, and meanwhile, more and more measures are used for improving the system performance and the reliability of the battery system of the electric vehicle, so that a battery charging technology is one of the important technologies. In a conventional battery system, a passive pre-charging scheme is generally adopted, that is, a pre-charging resistor is arranged in a charging circuit, and a bus capacitor is pre-charged through the current limiting effect of the pre-charging resistor. However, when the scheme is adopted for precharging, more heat is generated by the precharge resistor, so that the service life of the precharge resistor is influenced, and the precharge resistor is possibly invalid in heat resistance to cause ignition. In addition, heat dissipated by the pre-charging resistor can damage surrounding components and parts to influence the safety performance of the battery system, power consumption of the battery system can be improved, and the energy-saving performance of the battery system is poor. Disclosure of Invention The present invention aims to solve at least one of the technical problems existing in the prior art. Therefore, the invention provides a pre-charging circuit, a control method thereof, a battery management system and an electric automobile, which can improve pre-charging efficiency, reduce heating value in the pre-charging process, reduce power consumption of a battery system and improve safety and energy conservation of the battery system. The embodiment of the invention provides a pre-charging circuit, which comprises a capacitor, a power battery, a pre-charging inductor, a pre-charging switch and a switch control module, wherein the positive electrode of the power battery is connected with the first end of the capacitor, the first end of the pre-charging inductor is connected with the first end of the capacitor, the second end of the pre-charging inductor is connected with the second end of the capacitor, the pre-charging switch is connected between the negative electrode of the power battery and the first end of the pre-charging inductor in series, the input end of the switch control module is connected with the negative electrode of the power battery, the output end of the switch control module is connected with the pre-charging switch, and the switch control module is used for obtaining a circuit signal in the pre-charging circuit, comparing the circuit signal with a reference signal to obtain a voltage value comparison result and controlling the on-off of the pre-charging switch according to the voltage value comparison result and a clock signal. The pre-charging circuit provided by the first aspect of the invention has the advantages that in the pre-charging circuit, after a circuit signal in the pre-charging circuit is acquired, the switch control module compares the circuit signal with the reference signal to obtain a voltage value comparison result, the on-off of the pre-charging switch is controlled according to the voltage value comparison result and the clock signal, a first current loop for pre-charging the capacitor by the energy released by the power battery is formed under the condition that the pre-charging switch is conducted, and a second current loop for pre-charging the capacitor by the pre-charging inductance energy released by the pre-charging switch is formed under the condition that the pre-charging switch is disconnected. According to the scheme of the embodiment of the invention, the on-off of the pre-charging switch is controlled through the voltage value comparison result and the clock signal, the first current loop and the second current loop are switched through the pre-charging switch, so that the first current loop and the second current loop are alternately pre-charged for the capacitor until the voltage values at the two ends of the capacitor are the same as the voltage values at the two ends of the power battery. According to some embodiments of the invention, the switch control module comprises a signal detection amplifying module, a comparator and an NOT logic module, wherein the signal detection amplifying module is connected in series between the cathode of the power battery and the pre-charging switch and is used for obtaining the circuit signal and amplifying the circuit signal to output an amplified signal, the non-inverting input end of the comparator is connected with the output end of the signal detection amplifying module a