Electric Vehicle Insulation Detection System and Control Method Based on Adaptive Voltage Compensation and Low Frequency Injection

Abstract

The invention discloses an electric vehicle insulation detection system and control method based on self-adaptive voltage compensation and low-frequency injection. Adapt to voltage compensation, voltage sampling and alarm devices; inject low-frequency voltage signals into the adaptive voltage compensation circuit through the controller, and use the size of the insulation resistance to affect the impedance at both ends of the sampling circuit, so that the partial voltage of the sampling circuit in the circuit is changed, and the control The device obtains the divided voltage value in the sampling circuit through A / D, and uses the divided voltage value to calculate the insulation resistance of the battery pack to the vehicle ground. The self-adaptive voltage compensation of the invention solves the problem of false alarm of insulation failure caused by the voltage of the detection terminal being outside the normal range for a long time caused by the sharp rise or drop of the voltage of the detection terminal when the insulation resistance is suddenly increased by the low-frequency signal injection insulation detection method.

Description

technical field [0001] The invention relates to the field of electric vehicles, in particular to an electric vehicle insulation detection system and a control method. Background technique [0002] At present, batteries for electric vehicles are connected in series and parallel with multiple single cells to meet the demand for strong traction of vehicles. Using multiple series and parallel connections increases the total voltage of the battery pack, which is much higher than the safe human body voltage of 36V. Therefore, the insulation between the body and the battery pack is very important. The detection of insulation resistance is always one of the core contents in the research and development of electric vehicles. The insulation detection methods commonly used by domestic and foreign automobile manufacturers include the balanced bridge method or the high-voltage injection method, but these methods need to use a bridge circuit built with resistors to connect the battery pac...

AI Technical Summary

Problems solved by technology

However, in this method, when the insulation resistance changes suddenly, there is a defect that the detection terminal voltage rises or falls sharply and the detection terminal voltage is outside the normal range for a long time, resulting in false alarms of insulation failure.

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