Dynamic Performance Improvement of Singlephase DC-AC Converter with Non-linear Digital Predictive Control

Abstract

Single-phase voltage source inverter (VSI) still suffers a long settling time, and significant voltage overshoot/undershoot under the sudden output current change such as the impact load application. This paper first built the system differential equation to model and analyzed this comprehensive large signal dynamic process. And then presents a hardware-efficient digital control algorithm, as the improved capacitor charge balance control (CBC), forces the inductor current and capacitor voltage reach the target value by accurately tracking the predicted optimal trajectory during the transient process. A linear PI regulator is also employed under the steady-state. For the given main circuit parameters and detected load step change, the detailed mathematical derivation and design procedure are provided to guide the implementation. Finally, simulation and experimental results verify single-phase VSI attain the significant settling time reduction and minimized voltage variations. Fast load adjustment can be achieved without the consideration of control bandwidth limitation, like the conventional linear regulator under wide load range operation.