Analysis and Implementation of a Hybrid High-Power-Factor Three-Phase Unidirectional Rectifier

This paper describes the conception and analysis of a unidirectional hybrid three-phase rectifier suitable for medium- and high-power applications. The rectifier is composed of a single-switch diode bridge boost-type rectifier in parallel with a pulsewidth modulation (PWM) three-phase unidirectional boost rectifier. The objective is to obtain a structure capable of providing sinusoidal input currents with low harmonic distortion and dc output voltage regulation. The diode rectifier operates at low frequency and has a higher output power rating. Therefore, the PWM unidirectional rectifier is designed to operate with a small power rating and at a high switching frequency. The total harmonic distortion of the proposed structure varies between 0% and 32%, depending only on the amount of power processed by the PWM three-phase unidirectional rectifier. The rectifier topology conception, principle of operation, control scheme, and simulation and experimental results of a 20-kW laboratory prototype are also presented in this paper.