A control strategy for sinusoidal supply side convertors

Recent activity by legislative bodies and standards authorities within the European Community is causing an increased awareness of the problems associated with current harmonics and the resulting supply waveform distortion. As one of the main causes of this supply waveform distortion is nonlinear loads, such as 6-pulse rectifying equipment, alternative power conversion techniques, that draw continuous current from the network, need to be considered. This paper presents recent work in the development of a sinusoidal line side convertor for use with a variable speed AC drive. The paper will outline the power circuits and control system required for such a rectifier. A full explanation is provided of the strategy employed to achieve closed loop regulation of DC link voltage, a sinusoidal current waveform, full four quadrant power flow to the supply and the desired power factor. Measurements, taken from tests run on production equipment, will be used to demonstrate the performance of this rectifier