Switching‐angle‐based hybrid modulation method of full wind speed and low carrier wave ratio for direct‐drive permanent‐magnet wind power generation system

Abstract

A switching‐angle‐based hybrid modulation method of full wind speed and low carrier wave ratio for direct‐drive permanent‐magnet wind power generation system is proposed here, which order to improve the control performance of wind turbines in the full wind speed range. The combination manner of the proposed method is based on the harmonic distortion rate of the stator current, a modulation mode with a higher carrier wave ratio is adopted within the maximum switching frequency allowed by the system, the switching angle from optimized synchronous modulation also is introduced. In order to solve the problem of current impact caused by switching different modulation modes, the switching strategy between different modulation modes is developed from the perspective of harmonic current. And the sectors are redivided for the problem of sudden change in carrier wave ratio during switching, which improve the control effect of permanent‐magnet synchronous wind generator when changing the modulations modes. Finally, the feasibility and correctness of the proposed method are verified by theoretical analysis and simulation.