Resonant controller based single-phase Z-source inverter with LCL-filter

This paper presents a proportional plus resonant controller based single-phase Z-source inverter with LCL-filter for a utility connected system. Proportional plus integral (PI) control of ac systems has steady state error and can be eliminated by a resonant controller which incorporates model of input signal in its loopgain, by internal model principle. Small distributed generation (DG) system with alternate energy sources requires power conditioning units with low cost, high efficiency and tolerance to wide range of input voltage variation and has to perform various functions such as dc-ac conversion, system control and achieve power quality norms. Z-source inverter is a single-stage topology that can buck or boost output ac voltage. A two-loop control strategy for ac side control with utility current feedback and inductor voltage feedback as inner loop with voltage feed-forward is employed, on input side PID control is employed to regulate Z-source capacitor voltage which gives good transient response, also suppress load and source disturbances effectively. Simulation results are presented to validate proposed control strategy, experimental results are provided to validate the of PID control on dc side of ZSI.