A direct DC-link boost voltage PID-like fuzzy control strategy in Z-source inverter

This paper presents a direct peak dc-link boost voltage PID-like fuzzy controller in Z-source inverter. With this technique a constant peak dc-link voltage can be achieved with an excellent transient performance which enhances the rejection of disturbance, including the input voltage and load current variation, and solves the problem of the local dynamic output feedback stabilization of the serious non-minimum phase system, simplifies the controller design. The small-signal model of the Z-source network and non-minimum phase phenomenon of the control-to-output voltage transfer functions have been discussed in detail. The two zeros (a LHP zero and a RHP zero) of the control-to- peak dc-link voltage transfer function results in the impossible to design a good controller for dc-link voltage with linear strategy. A phase plane is presented to describe the control effort transient response, analyze system stability, and modify the rule matrices of fuzzy controller. The proposed technique was verified on a 20-kW prototype. The experimental results meet the simulation and analysis results very well.