Affordable rectifier circuit - Rectifier circuit with just two semiconductor switches

The power grid usually provides alternating or three-phase current. But the energy transition requires conversion to adjustable, electrically isolated direct current for such applications as electrolysis and charging batteries and LED lights. This requires a number of rectifier circuits: Each circuit uses up to 14 or more disengageable semiconductor switches, making the process very expensive. 

The invention from the Bielefeld University of Applied Sciences and Arts is different. It requires just two disengageable semiconductor switches, but can still provide electrically isolated output direct current of selectable magnitude in a pulse-width modulation rectifier. The rectifier circuit consists of three transformers with separated primary-side coils, one secondary part per phase, two primary-side circuits, and three secondary-side circuits. The primary-side circuits are switched alternately at a frequency greater than the supply frequency. The secondary-side circuits are switched at a frequency greater than the primary-side switching frequency. The secondary-side semiconductor switches are interconnected with an inductance, a diode, and a common capacitance to form a boost converter (see figure). Other circuit advantages are the affordable, lightweight transformers and the high level of efficiency.