Application of Three-level Converters to Wind Power Systems with Permanent-magnet Synchronous Generators

This paper presents the design and implementation of a power control system for variable-speed, permanent-magnet synchronous generators. In this system, a three-phase, full-bridge rectifier and a single-phase, three-level inverter are proposed to convert the three-phase varying voltage and frequency generated by wind to single-phase source with constant voltage and frequency. Specifically, the output power of the overall system is adjusted by detecting the dc-link voltage as well as output voltage and current of inverter. A novel three-level dc/dc power converter is designed to charge and discharge the battery set, while fixed-voltage control method is used to supply load power when wind speed is low. The single-phase, three-level inverter operated under voltage-controlled mode by using new two-axis amplitude-lock-loop technique algorithm can provide a single-phase source with fast response, stable and low harmonic distortion power to load. The performance of the system is simulated by Matlab/Simulink. Then, a low-cost, 16-bit digital signal processor (DSP, TMS320LF2407A) is used to implement the control functions of the generation system. The experimental results for a 750 W generation system show that the output voltage and frequency can be held at 110/220 V and 60 Hz, respectively, when the speed varies from 200 to 450 rpm. The feasibility of the generation system is verified experimentally.