MS student Jason Paximadas with Advisor A. Banerjee

Modern, megawatt-scale wind turbines present unique challenges to power electronics design. Unlike double-fed induction-generator based systems, high power density permanent magnet synchronous machine (PMSG) wind turbines prevent the designer from building partially rated power electronics. As deployment of wind turbines expands, so too has the need for reliable, low-cost rectifiers for PMSG-based wind turbines. Previous work on this project has demonstrated how a PMSG-based wind turbine can be tied to a dc grid with reduced active switch rating. This research investigates how this architecture can be extended to tie to an ac-grid. The proposed system is shown in Figure 1 and consists of two power paths. The first processes the majority of the power with diodes and low-frequency switches. The second processes the rest of the power with high-frequency switches. Each power path drives one end of an open-winding transformer which ties the system to the grid. The goal is to show how this composite architecture provides better reliability and efficiency than a conventional back-to-back architecture without significant drawbacks. A bench-top model (Figure 2) has been constructed that models the proposed composite inverter architecture. The model verified our equations for the power sharing between the paths. It also demonstrated the inverter’s dynamic performance and the efficacy of the chosen modulation scheme. Our current goal for the bench-top model is to verify design equations that bound the energy-storage requirements of the dc-link capacitors that must be placed on each dc bus. This research is funded by Advanced Research Projects Energy, U.S. DOE.

Figure 1: System with two power paths tieing system to the grid.

Figure 2: Bench-top model with proposed composite inverter architecture.