A Small-signal analysis and PI controller design for a five-level modified quasi-Z-source H-bridge inverter

Abstract

This paper presents a single-phase five-level inverter topology using a modified quasi-Z-source network (Five-level Modified Quasi-Z-source H-bridge Inverter – 5L-MqZS-HBI), which combines two quasi-Z-source networks with an H-bridge inverter. 5L-MqZS-HBI is designed to reduce the number of inductors, improve overall efficiency, and enhance voltage gain while maintaining the ability to generate multilevel output voltages, making it suitable for applications requiring high-quality, high-voltage outputs with low harmonic distortion under low input voltage conditions. A small-signal analysis is performed considering parasitic elements of inductors and capacitors to establish the relationships between capacitor voltage, inductor current, and control parameter, so the system transfer function is derived to design a PI controller that ensures stable output voltage despite changes in input voltage or load. The paper also presents detailed operating states, evaluates controller performance, efficiency, and THD, and confirms the analysis through PSIM, MATLAB simulations and laboratory experiments.