Although the input filtering of the high-voltage component, the theoretical value of the Y capacitance of HV+ and HV- to PE is the same, due to the tolerance of the Y capacitor itself and the difference of parasitic capacitance in parallel with it, CY1 and CY2 are often unequal, but because the bridge method is that the upper bridge arm and the lower warp arm are not opened and collected at the same time, and the larger the Y capacitance, the greater the impact on the insulation resistance measurement, so we generally calculate the external CY1 and CY2 in the static test in the following way:

Note: The total capacity between the live parts of the B-class voltage and the electric platform does not exceed 0.2J at the maximum working voltage, and the energy stored in the maximum working voltage is not more than 0.2J (GB 18384-2020 in Auto), and the maximum stored power (Q=0.5 × C × U^2) of the positive side capacitance Cy+ or negative side capacitance of the B-class voltage circuit is 0.2J.

For a 1500V energy storage system, the Y capacitor needs to be less than 230nF, and can choose 200nF in this article’s evaluation.