Digital gain-scheduled control of a high frequency parallel resonant DC-DC converter

The nonresonant-coupled parallel resonant converter is discussed and a reference classical analog controller is designed and simulated. Based on the strong relationship observed between low-frequency converter gain and operating point, a band-limited gain-scheduled digital controller is proposed, designed, and simulated, showing 5:1 improved worst-case control bandwidth as compared with the analog controller. A prototype is designed and built which experimentally validates the simulation results with good correlation. The effect of digital modulator resolution is discussed.