Optimized design of wind energy conversion systems with single-phase AC-link

Major concerns in the converter design are the efficiency and the power density. In this paper is presented a comparison of six modular power converter solutions based on single-phase link for offshore wind turbines with permanent magnet synchronous generator. The scheme of the converter module considered is based on three stages: 3AC-AC converter, a single-phase high-frequency transformer and a full-bridge diode rectifier. The conventional 3AC-AC back-to-back converter and the Reduced Matrix Converter are the compared topologies, combining with IGBT with three blocking voltage (1.7kV,3.3kV,6.5kV). Analytical models and numerical simulations are considered in order to evaluate the converter efficiency and the power density as function of AC-link frequency and the number of converter modules. It has been found that the Reduced Matrix Converter topology will lead a higher efficiency and a higher power density when it is used with lower voltage level. Also, the converter solutions based on low blocking voltage IGBTs presents higher efficiency than switch based on high blocking voltage IGBTs, leaving evidence of a deficiency in the technology for higher blocking voltage.