Sinusoidal line current rectification with a 100kHZ B-SIT step-up converter

A step-up converter circuit for the sinusoidal line current rectification at a unity power factor is described. A Bipolar-Static-Induction-Transitor (B-SIT) with extremely fast switching times is utilized. The gate drive and the snubber circuits are presented. A new way to achieve current hysteresis control without noise problems for switching frequencies up to 100 kHz is developed. Measured overall efficiency and the transistor losses are presented. At 1 kw dc output, the total transistor switching and conduction losses are 9 watts at about 100 kHz switching frequency. The overall rectification efficiency is in a 97–98.5% range. Justification for the use of step-up converters is given. Component selection and the stability in the feedback loop is analyzed. The converter is especially advantageous for single phase in — three phase out, variable frequency ac motor drives in lower horsepower applications.