New wide input voltage range three-phase unity power factor rectifier formed by integration of a three-switch buck-derived front-end and a DC/DC boost converter output stage

A new three-phase unity power factor rectifier with a three-switch buck-derived input stage and a DC/DC boost converter output stage is presented. This system has a wide input voltage range and a continuous sinusoidal time behavior of the input currents lying in phase with the input voltages which is also guaranteed in case of a failure in one phase of the mains. The input currents are controlled using a switching state sequence showing minimum switching losses. A multi-loop system control is realized by an outer output voltage controller and an inner-loop buck+boost inductor current controller. Furthermore active damping of the input filter resonance is provided. For increasing the output power of the system a parallel connection of two interleaved units is proposed. There, a low input current ripple is achieved, and the cut-off frequency of the input filter can be shifted to higher frequencies (resulting in improved control dynamics and a more compact design downsizing of the inductors and of the input filter)