A comparison of output envelope waveforms of the delta-sigma modulated class D series resonant inverter

The output envelope waveforms of the delta-sigma modulated class D series resonant inverter is analyzed, compared, and discussed based on the simulation results with Matlab Simulink simulator. The class D inverter operating at 200 kHz generates 50 Hz envelope waveform through the additional switching legs. Firstly, the relationship between the feed-back gain of the delta-sigma modulator and the output envelope waveforms is clarified. Secondly, the variable parameters are expanded to the loaded Q-factor Q/sub L/. For Q/sub L/ = 10 to 10000, the output waveforms are analyzed. The simulation results show that THD is held under 3 % from Q/sub L/ = 50 to 100. The obtained envelope waveform is highly qualified as an ac power source.