The experimental performance of a multi-level AC-DC power electronic converter for PMG-based WECSs

This paper experimentally tests a new multi-level generator-side ac-dc power electronic converter (PEC) for applications in permanent magnet generator (PMG)-based wind energy conversion systems (WECSs). The tested generator-side PEC is designed as a cascaded H-bridge multi-level PEC, and is fed by one 3φ supply. The used H-bridge cells are modified such that each cell is composed of a forward half-bridge and a backward half-bridge. The forward half-bridge produces a dc voltage, while the backward half-bridge provides a path for the current to flow to the next H-bridge cell (connected in series). The new multi-level ac-dc PEC is implemented for experimental testing as a generator-side ac-dc PEC in a 7.5 kW PMG-based WECS. The tested acdc PEC is operated using switching signals that are generated by the sinusoidal level-shifted pulse width modulation strategy. Experimental test results demonstrate reduced harmonic distortion in input currents, efficient and high quality power transfer from the PMG to the dc link, and high input power factor.