Control and modulation techniques of Z-source converter

This chapter presents an overview of control and modulation techniques for Z-source converters (ZSCs) used for electric power conversion. ZSCs are categorized into four main categories: DC/DC converters, DC/AC inverters, AC/AC converters, and AC/DC rectifiers. ZSCs are further classified into voltage-fed or current-fed, and non–transformer based or transformer coupled-inductor based. Modulation techniques for traditional three-phase H-bridge topologies (two-level) are classified as sine pulse width modulation and space vector modulation, with several modifications available in the literature. Modulation techniques for three-phase multilevel topologies, matrix topologies, and DC/DC converters with an intermediate H-bridge are also discussed. The impact of modulation strategies on the reliability and harmonics of impedance-source inverters is analyzed. The control strategy of ZSCs is also discussed, with various closed-loop control methods presented in the literature. The chapter concludes that proper modulation and control techniques are necessary to achieve the maximal voltage boost and minimal harmonic distortion, lower semiconductor stress, and minimal number of devices commutation per switching cycle in ZSCs.