A control strategy for direct-drive permanent-magnet wind-power generator using back-to-back PWM converter

Since variable-speed generation has a higher energy capturing and converting efficiency than the fixed-speed system, new proposals for wind power system utilize variable-speed generators are introduced, among which permanent-magnet synchronous generator(PMSG) is an attractive choice. This paper describes a sensorless vector control strategy for a direct-driven PMSG, which is connected to the power network through a fully controlled back-to-back PWM converter. The generator side converter is controlled to obtain maximum power from the incident wind and the grid-side inverter is to maintain DC-link voltage constant and regulate the power factor of the windmill. An experimental prototype, which represents a 3.7 kW variable speed generation system, is carried out to verify the control method, and experimental results are given to illustrate the performance of the system.