| Summary: | 碩士 === 國立清華大學 === 電機工程學系 === 100 === Due to the merits of high power density, high efficiency, and easy control of BLDC machines, a BLDC generator is rather suitable for application of small wind power generation systems. However, the commutation current ripples caused by conventional BLDC machine controls may result in torque ripples and vibration noise. Hence, the main motivation of this thesis is focused on solving the above problem through proper power converter design.
Basically, the major contributions of this thesis may be summarized as follows. First, a novel three-phase AC/DC converter, which contains only a single active switch, is proposed to integrate with the BLDC generator, so that the generator inductance can be fully used and the input/output currents become more smooth to reduce EMI. Second, to achieve a better performance, a simple control strategy which requires only one current sensor is presented to reduce the commutation torque ripples. The control strategy does not require any torque observer and calculation of commutation time as the existing paper. Third, the mathematical model of the proposed converter is derived for understanding the fundamental characteristics of the converter and used for the design of the closed-loop control. Finally, a 200W prototype is constructed for verifying the effectiveness of the proposed converter. Experimental results show that the resulting generator commutation current ripple can be reduced by 49% as compared with a conventional converter.
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