Novel PWM-based control strategy of HF link SMR with sinusoidal line current

Abstract

A novel PWM control strategy is presented, based on the current-mode control approach for a high-frequency (HF) link switch mode rectifier (SMR). This control strategy allows sinusoidal wave shaping of the line current and power-factor correction while ensuring amplitude modulation of the HF transformer waveform in a single power processing stage. The method is based on the sampling of the inductor current during transfer time into several HF transfer cycles using a sampling signal. The sampling signal is introduced to avoid HF transformer saturation and to allow operation at an extremely high frequency (50 k-100 kHz). Power MOSFETs modules (450 V/50 A) which are suitable for operation at frequencies ranging up to hundreds of kHz are used for the experimental set-up. A bridge configuration which is a boost-like convertor is used for the boosting and the inverting stages. The proposed HF link SMR is intended for use in high-frequency link UPS equipment for a power range of 1–5 kVA. Analysis and experimental results show that operation is possible with a sinusoidal line current in phase with the utility voltage and with approximately unity power factor.