A Unified Digital State-Feedback Control Strategy With Explicit Decoupling for a Hybrid Multiport DC–AC Converter in Standalone PV-HESS Applications

This paper presents a hybrid multiport DC–AC conversion system for standalone AC power supply, consisting of a multiport DC–DC stage cascaded with a single-phase voltage-source inverter (VSI). The multiport DC–DC stage interfaces a photovoltaic (PV) module, a battery bank, and a supercapacitor bank, while the VSI directly supplies off-grid AC loads. Unlike conventional approaches that employ separate controllers for the DC–DC and DC–AC stages, this work proposes a unified digital state-feedback control strategy with explicit decoupling networks. This framework enables fully independent and simultaneous regulation of all four ports (PV voltage, battery current, supercapacitor current, and AC output voltage) while effectively mitigating the strong cross-coupling among the DC ports and between the DC–DC and DC–AC stages. The proposed controller is supported by a comprehensive small-signal model of the hybrid system and is validated through PSIM simulations and experimental results from a laboratory prototype. The results demonstrate fast inner-loop dynamics, negligible cross-coupling under reference changes, and robust operation across multiple power-flow modes.