High efficiency 18 kW HF link, three-phase, soft commutated DC-AC-AC converter (study of start and stop operations)

Abstract

In this paper, a new DC/AC/AC converter for variable speed AC drives using soft commutation technique is described. It consists of a dual-thyristor voltage inverter connected to cycle-converters. It combines the advantages of a soft commutated converter and those of PWM control (constant commutation frequency, simple control). The discussed converter is realised with IGBTs; it supplies trapezoidal currents to a three-phase 18 kW brushless permanent magnet motor, with 20 kHz chopping output frequency. The paper focuses on the start and stop transients.