An Isolated High-Frequency DC–AC Converter Based on Differential Structure With Ultralow Distortion Output Voltage

With the background of power supplies for high-precision apparatuses, an isolated high-frequency dc-ac converter based on a differential output structure is proposed. It is composed of two phase-shifted full bridges (PSFBs) that share a common half-bridge as the lagging leg on the primary side. Two current-doubler synchronous rectifiers (CDRs) constitute the differential output structure on the secondary side. The ac output is synthesized by the two PSFB-CDRs generating the same dc bias and phase-reversed ac components. Compared with traditional solutions, the new circuit has the potential capability to obtain an ultralow distortion output voltage without using special control or compensations. Moreover, zero voltage switching is realized in the primary circuit within a wide load range, whereas zero current switching is achieved in the secondary circuit. Operation principles are analyzed, and a 1-kW prototype is built to validate the proposed scheme.