With the development of the electric vehicle, the charging pile of the electric vehicle has started to be extended and applied. For electric vehicles, the battery management system detects the battery through the precision shunt, and will prompt the owner to charge the charging pile when the battery is found to be insufficient. The frequent problem of charging piles is the phenomenon of electric leakage, which is very unsafe for both the charging pile and the electric vehicle. In order to provide better safety, the charging pile needs to carry out electric leakage detection on the following points.

Firstly. capacitance of charging pile leak current.
Capacitor dielectric can not be absolutely conductive, when capacitance plus DC voltage, the capacitor will have leakage current. If the leakage current is too large, the capacitor will heat damage, and may affect the precision resistor, also lead to resistance damage. Except for electrolytic capacitance, the leakage current of other capacitors is very small, so the insulation performance is expressed by the parameters of insulation resistance, while the electrolytic capacitance is characterized by leakage current because of its large leakage current.
 
It is observed that the charge current changes greatly with the application of rated DC operating voltage to the capacitor, and decreases with time, and the final current is called leakage current when a certain terminal value is reached.
 
Secondly. charging pile semiconductor element leakage current
The PN junction flows through a tiny current at the cutoff. D-S forward bias, G-S reverse bias, conducting channel open, D to S current flow. But in fact, due to the existence of free electrons, the free electrons are attached to SIO2 and N, resulting in leakage current of D-S.    

 
Thirdly, power supply of charging pile leakage current.
In order to reduce interference in switching power supply, EMI filter circuit must be provided according to national standard. Due to the relationship of EMI circuit, there is a small current to the ground after the switch power supply is connected to the electric supply, which is called leakage current. If not grounded, the housing of the computer will have 110 volt voltage on the ground, will feel numb by hand, and will also have an impact on the operation of the computer.
 
 
Fourthly, leakage current of charging pile filter\
The development of electric vehicles using precision shunts have reached a new stage. People have always paid attention to the internal safety problems of electric vehicles, in which leakage current fault is a problem that must be solved by various design manufacturers. For the traditional AC type leakage protection, the current technology is relatively mature.