Techniques for minimizing the input current distortion of current-controlled single-phase boost rectifiers

Techniques for minimizing the input current distortion of current-controlled single-phase boost rectifiers are described. The switching patterns of several boost rectifiers are examined to identify the nature of their input current waveforms. This analysis is used to examine the low-frequency current distortion levels, and hence the power quality, associated with the rectifiers. A PWM (pulse width modulation) strategy that selectively switches between positive unipolar PWM and negative unipolar PWM, called phase-adjusted unipolar PWM, is shown to produce the lowest current distortion levels. A novel two-switch asymmetrical half-bridge rectifier is presented that draws an input current at a unity fundamental power factor and with the same low distortion as obtained with the four-switch H-bridge rectifier. The operation of the various rectifiers is examined with reference to theoretical predictions, circuit simulations, and experimental results. This analysis is used to compare the performances of the various rectifier switching patterns.>