Highly efficient AC-DC converter for small wind power generators

Abstract

A highly efficient AC-DC converter for small wind power generation systems using a brushless DC generator (BLDCG) is presented in this paper. The market standard AC-DC converter for a BLDCG consists of a three-phase diode rectifier and a boost DC-DC converter, which has an IGBT and a fast recovery diode (FRD). This kind of two-stage solution basically suffers from a large amount of conduction loss and the efficiency greatly decreases under a light load, or at a low current, because of the switching devices with a P-N junction. In order to overcome this low efficiency, especially at a low current, a three-phase bridgeless converter consisting of three upper side FRDs and three lower side Super Junction FETs is presented. In the overall operating speed region, including the cut-in speed, the efficiency of the proposed converter is improved by up to 99%. Such a remarkable result is validated and compared with conventional solutions by calculating the power loss based on I-V curves and the switching loss data of the adopted commercial switches and the current waveforms obtained through PSIM simulations.