The MK-APF active power filter employs an external current transformer (CT) to continuously monitor the load current. Through internal DSP calculations, it extracts the harmonic components from the load current. Subsequently, these extracted harmonics are transmitted to the internal IGBT via PWM signals. This control mechanism prompts the inverter to generate a current of equivalent magnitude and opposite direction to the load harmonics. This current is then injected into the power grid to compensate for the harmonic currents, effectively achieving the filtering function.