Total harmonic distortion reduction add-on unit for three-phase diode rectifiers

An active add-on option for 208 VLL/60 Hz passive three-phase rectifiers is presented. The active optional circuit is implemented as 'centretapped ' full-bridge stage and guarantees low-harmonic input currents and unity power factor. The active unit is able to operate for a wide frequency range and therefore applicable for high-(e.g. >100 kW) and low-power applications. Some basic considerations such as principle operation, duty cycles, voltage/current stress of switches and design of inductors are discussed and additionally supported by simulation results. Applicability of emerging wide bandgap power devices such as silicon carbide MOSFETs, which improve converter efficiency and power density, is furthermore briefly discussed.