Current harmonics reduction method of electrolytic capacitor-less diode rectifier using inverter-controlled IPM motor

This paper proposes a current harmonic reduction method to improve the input current waveform in electrolytic capacitor-less single-phase to three-phase power converters. Typically, the back EMF of an IPM motor is not sinusoidal and contains harmonics caused by the rotor structure; therefore, it causes harmonic distortion in the motor control system and generates harmonics in the input current. In this study, the cause of the input current harmonics induced in the back EMF and the d-q axis current controller are analyzed. Furthermore, this paper proposes a control method to reduce the current harmonic distortion. In the proposed method, the d-q axis voltage references are compensated to reduce the input current harmonics. The d-q axis compensation voltages are obtained by a feed-forward controller. The maximum power factor obtained by the proposed method is 98.0[%]. The experimental results confirm that the proposed control method conforms to the EN61000-3-2 guideline.