A new multi-level AC-DC power electronic converter for applications in PMG-based WECSs

This paper presents the development and performance evaluation of new multi-level ac-dc power electronic converter (PEC) for applications in permanent magnet generator (PMG)-based wind energy conversion systems (WECSs). In order to feed the multi-level ac-dc PEC from one 3φ supply, it is built by using modified H-bridge cells. Each of the modified H-bridge cells is constructed from forward and backward half-bridges. The forward half-bridge conducts the current to the output side of level n, while the backward half-bridge conducts the current from level n to level n + 1. The developed multi-level ac-dc PEC is operated by switching signals generated by the sinusoidal level-shifted pulse width modulation (LSPWM) switching strategy. The multi-level ac-dc PEC is implemented for evaluating its performance, when used as a generator-side PEC in a PMG-based WECS. Performance results demonstrate reduced harmonic distortion in the input ac currents, improved power transfer from the PMG to the dc link, and reduced pulsations in the PMG electromagnetic torque.