Single switch three-phase ac to dc converter with reduced voltage stress and current total harmonic distortion

A three-phase ac/dc converter with low-voltage stress and current total harmonic distortion (THD) for micro-scale wind turbines is proposed in this study. A coupled inductor and buffering capacitors are integrated in the proposed converter to reduce the voltage stresses on the main switch and diodes. Moreover, the discontinuous conduction mode power factor correction technique is adopted to reduce the generator current THD. Corresponding operation principles of the proposed converter are also analysed and illustrated. A prototype with rated output power 200 W was constructed for evaluating the validity and performance of the proposed converter. From the experimental results, it can be seen that the voltage stress of all the active switches and diodes is reduced to half of the output voltage. Owing to the reduced voltage stress, the generator current THD and converter efficiency are both improved with respect to the conventional three-phase single switch ac/dc converter. The efficiency is improved to about 92% which is 10% higher than the conventional single switch rectifier and the current THD is reduced by 2-6%.