Star-C - A New Converter Topology

Abstract: Power electronics is today used almost everywhere. The development of power electronics hardware is fast, pushing the performance limits. Still the conventional two level converter is the most commonly used converter on the market. The output voltage of the conventional two level converter is generated as pulses. The pulses are generated with semiconductor switches with short switching times to keep the switching losses at an acceptable level. The big voltage steps combined with the short switching times cause very high voltage derivatives. Such derivatives generates high amounts of electro magnetic-emissions that may cause EMC-problems. In this thesis two alternatives, with lower harmonic content, are investigated: multilevel converters and the new StarC converter. Multilevel converters synthesizes the output voltage with pulses, much like the two level converter, but the DC-voltage is divided into more than two levels which results in smaller voltage steps and thereby reduced harmonic content. The StarC converter synthesizes the output voltage by charging output capacitors with high frequency current pulses generated with a resonance link. The output voltage from the StarC converter is close to sinusoidal with very low harmonic content. The investigated converters are simulated and compared in terms of total harmonic distortion, efficiency, current ripple and cost. The simulated application is traction of a car, with a motor model provided by Volvo used in the simulations.