Converts the motor’s PWM output signal to a smooth sine wave with low residual ripple voltage, preventing damage to the motor’s winding insulation. Reduce the phenomenon of resonance caused by distributed capacitance and distributed inductance due to the length of the cable, eliminate the motor overvoltage caused by high dv/dt, eliminate the premature damage of the motor caused by eddy current loss, and the filter reduces the audible noise of the motor.