Novel Random-Harmonic Elimination PWM Technique for Single-Switch Three-Phase AC-DC Buck Converter

A novel PWM technique for single-switch three-phase AC-DC buck converter is proposed to reject input voltage fluctuation, obtain high quality output voltage and realize open-loop operation mode. By controlling the duty cycle of the switch which tracks the change of input voltage, the energy supplied by AC mains and the energy consumed in load can keep invariable in every switching cycle. So the output DC voltage maintains at a constant value and random-harmonic voltage contained in input stage is eliminated. Based on the principle of energy conservation, the system operation is analyzed and the control strategy is introduced in detail both in discontinuous conduction mode (DCM) and continuous conduction mode (CCM). Experimental results are provided to show its validity and feasibility