A novel three-phase AC to DC power convertor is proposed to achieve sinusoidal current waveform and unity power factor at the input, and to simplify the control of all switches. In addition, the new convertor has both step-up and step-down capability and no current sensor is required for the current control. The steady-state analysis such as DC model, harmonic analysis of the input current and some design considerations are presented. Finally, some experimental results are given for demonstration.