Electric automobile insulation impedance detection method

Abstract

The invention relates to an insulation impedance detection method for an electric automobile, and directly calculating the insulation resistance value of the positive and negative poles of the power battery of the electric vehicle on the vehicle body. The original detection circuit is connected with a resistor between a positive bus and a negative bus of the power battery pack, the insulation performance of the vehicle body is reduced by the access of the detection device, and the self-discharge rate of the battery can be increased.; a high-voltage isolating switch is adopted for controlling the positive and negative bus ends of the power battery, the detection resistor is not introduced when the insulation detection is not carried out, and adverse effects on the vehicle body are avoided.The electric automobile insulation impedance detection method is simple to operate and can accurately and effectively detect the insulation resistance.

Description

technical field [0001] The invention relates to an impedance detection method, in particular to an electric vehicle insulation impedance detection method. Background technique [0002] Electric vehicles are complex mechatronic products, many of which include power batteries, motors, chargers, energy recovery devices, auxiliary battery charging devices, etc. will involve high-voltage electrical insulation problems. The working conditions of electric vehicles are relatively harsh. Vibration, corrosion of acid and alkali gases, changes in temperature and humidity may cause rapid aging of power cables and other insulating materials or even damage to insulation, greatly reducing the insulation strength of equipment and endangering personal safety. The insulation performance of the DC system directly affects the reliability of the DC circuit. If two-point grounding occurs in the DC system, it may cause serious consequences. At present, the main insulation resistance measurement m...

AI Technical Summary

Problems solved by technology

Among them, the megohmmeter measurement method needs to generate a high-voltage excitation, which will bring additional safety hazards when the battery is working

For the AC signal injection method, because of the complex load and working conditions of the power battery in electric vehicles, there will be a lot of noise and spikes at both ends of the battery, which will greatly interfere with the acquisition of the injected signal, and finally make the measurement of the insulation resistance fluctuate greatly. , and the measurement error is large

In addition, when using the auxiliary level method to measure insulation resistance, because the insulation resistance value is generally large, the current value is very small, making it difficult to measure

Another more serious problem is that the internal resistance of the auxiliary level is milliohm level, so that the negative pole of the DC high-voltage battery in the system is equivalent to being directly connected to the body ground, which greatly increases the danger of the positive pole.

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