An Active Filtering Method Based on Low Frequency Electromagnetic Interference Cancellation for Motor Drive System of Electric Vehicle

Aiming at the problem that the low-frequency conducted electromagnetic interference of the high-voltage DC power supply of the electric vehicle motor drive system is difficult to suppress, a design method of a current sensing and voltage compensation active filter is proposed. The filter is composed of a current detection probe, RF transformer, an amplifier circuit and a current injection probe. The filter can generate compensation current to cancel the electromagnetic noise on the DC high voltage power lines. The lumped parameter models of current probe, RF transformer, and amplifier are formulated, which are integrated to compose the equivalent circuit model of the proposed active filter system. The accuracy of the model is verified in comparison with the test results. Simulation and experiments are conducted to validate that the designed filter can realize an insertion loss greater than 40dB in the frequency band of 10kHz-500kHz.