Series resonant AC-power interface with an optimal power factor and enhanced conversion ratio

Abstract

A method of power pulse modulation with internal frequencies of tens of kHz which is also suitable for multikilowatt power levels is applied to a series-resonant converter system for generating synthesized multiphase bipolar waveforms with reversible power flow. The power circuitry of the converter is provided with one single high-frequency resonant link in the direct energy path. Natural current commutation of the thyristors is obtained by the use of a series-resonant circuit for power transfer and control. Consequently, switching losses can be reduced to a minimum without compromising the reliability of the solid-state components. Test results of a converter system generating three-phase sinusoidal waveforms demonstrate the significant aspects of this improved series-resonant power processor and indicate the possibilities of fast-acting DC and AC converter systems with reversible power flow.