Insulation resistance detection method and device based on full-bridge insulation detection circuit

Abstract

The invention relates to the field of power batteries, and provides an insulation resistance detection method and device based on a full-bridge insulation detection circuit. The method comprises the steps: switching on a first switch, switching off a second switch, and collecting the voltage of a first insulation resistor as a first voltage; calculating an estimated voltage as a first estimated voltage according to a first estimation model; switching on the second switch and switching off the first switch, and collecting the voltage of a second insulation resistor as a second voltage; calculating an estimated voltage as a second estimated voltage according to a second estimation model; when the deviation between the first estimated voltage and the first voltage and the deviation between the second estimated voltage and the second voltage are not smaller than preset values at the same time, adjusting the estimated resistance value, repeatedly executing the above steps until the estimated resistance values are smaller than the preset values at the same time, and taking the current estimated resistance values of the first insulation resistor and the second insulation resistor as the resistance values of the first insulation resistor and the second insulation resistor respectively. According to the invention, the accurate value of the insulation resistor can be obtained, and the detection time is greatly shortened.

Description

technical field [0001] The invention relates to the technical field of power batteries, in particular to an insulation resistance detection method and device based on a full-bridge insulation detection circuit. Background technique [0002] The power battery of an electric vehicle needs to meet the power and performance requirements of the electric vehicle. The maximum output voltage and output current of the power battery will reach several hundred volts and tens of amperes respectively. cause great harm to human life. General vehicle collisions, frequent vehicle vibrations, and aging insulation facilities can all cause failure of the insulation resistance of power batteries. [0003] In order to solve the above problems, the insulation resistance value between the power battery and the vehicle chassis must be monitored in real time, and the monitoring must be fast and effective, so that the danger of vehicle insulation damage can be detected in time and dealt with quickly...

AI Technical Summary

Problems solved by technology

Due to the long detection period, before the vehicle is powered on at high voltage (500ms), the insulation resistance in the package cannot be detected, and the insulation resistance of the vehicle can only be detected after the high voltage is powered on.

Therefore, it is impossible to distinguish whether it is the leakage in the high-voltage battery pack or the leakage of the whole vehicle outside the package.

In addition, due to the differences in the capacitance of different vehicles, the time required to wait for the circuit to enter or approach a stable state is also different, and the error in the estimation of the waiting time will affect the calculation accuracy of the insulation resistance

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