Class D series resonant converter controlled with FPGA-based delta-sigma modulator

A 1st order 1-bit delta-sigma modulator to control a Class D series resonant converter is built with an FPGA. The target reference and the feedback gain are freely chosen. A Class D series resonant converter designed at an operating frequency of 200 [kHz] was built and driven by the FPGA-based delta-sigma modulator. Maintaining zero-current switching (ZCS) operation, the output voltage and power were changed from 0.945 [V], 89.1 [mW] to 8.22 [V], 6.75 [W] in the circuit experiments fed by 20.0 [V] dc-voltage source. The measured power conversion efficiency was from 71.8 [%] to 83.0 [%]. These performances have also been confirmed with MATLAB simulink simulator. In the frequency domain, no specific component was found except the switching frequency and its 2nd harmonic in the observed output voltage.