Efficient high-frequency soft-switched power converter with signal processor control

DC/AC high-power, high-density converter structures and topologies are evaluated. The direct DC-low frequency-AC structure with the dual active bridge (DAB) topology is selected together with insulated gate bipolar transistor (IGBT) switches at 100 kHz, 20 kVA. A novel control strategy for the DAB and series-loaded resonant converters is introduced. It gives the possibility of fixed-frequency, zero voltage switching in the entire converter output V-I-plane. Design equations are presented. A method for comparing topologies by mapping stress levels in the output V-I plane is demonstrated. Experimental results from a small-scale model are shown, with good correspondence to simulation waveforms. The converter will be driven by an IBM PC/MS Windows based control system, of which the core is a 32-b digital signal processor connected to a programmable gate array holding all switch control circuitry.<
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