Three-phase AC-to-AC series-resonant power converter with a reduced number of thyristors

Power pulse modulation with internal frequencies of tens of kHz and suited for multikilowatt power levels is applied to a series-resonant converter (SRC) system for generating synthesized multiphase bipolar waveforms with reversible power flow and low distortion. The high pulse frequency allows the application of the principle of modulation and demodulation for fast system response. The use of an SRC for power transfer and control obtains natural current commutation of the thyristors and the prevention of excessive stresses on components. Switches with bidirectional current conduction and voltage blocking ability are required. The conventional series-resonant AC-AC converter applies a total for 24 antiparallel thyristors. An alternative circuit configuration for the series-resonant AC-AC converter with only 12 thyristors is presented. Use of the converter results in a higher efficiency and lower costs