Z-source Inverter Control Method

This paper focuses on the research of control strategies for the recently presented Z-source inverter.Traditional three-phase inverters are based on two basic topologies-----the currentsource and the voltage source. Either voltage source inverter (VSI) or current source inverter (CSI) has their conceptual and theoretical limitations, thus resulting in high cost as well as low efficiency in many applications. The Z-source inverter overcomes the problems and limitations of traditional VSI and CSI and provides a novel powerconversion concept. Two typical applications of Z-source inverter-----for fuel cellapplication and for adjustable speed drives are adopted to illuminate these new characteristics.Sinusoidal pulse width modulation (SPWM) and space vector pulse width modulation (SVPWM) techniques are widely used in traditional inverters for low THD, constant switching frequency, convenient realizations etc.This paper presents several SPWM and SVPWM control methods for Z-source inverter based on systematic analysis of traditional SPWM and SVPWM control strategies and unique working characteristics of Z-source inverter. Traditional SPWM and SVPWM control methods are modified for Z-source and the DSP realizations are presented in this thesis. Validity and feasibility are validated by simulation and experimental results. Switching voltage stress, current stress and the choice of L and C parameters in the Z network with different control methods are analyzed. These researches present the theoretical basis for the choice among different control methods.