Modeling and Control of a Zero-Current-Switching DC/AC Current-Source Inverter

Choosing a dc/ac converter is mainly a compromise among three major issues, namely: 1) efficiency; 2) waveform quality; and 3) cost. This paper considers a zero-current-switching (ZCS) current-source inverter (CSI) as a viable choice for many applications. It features low conduction and switching losses, inherent output filtering, capability of withstanding short circuits, and the opportunity to use thyristors. Despite these promising characteristics, this inverter exhibits a nonlinear relationship between the modulation index and the output current. Moreover, the resonant modes that are generated by the load-filter interaction must be damped. Since the previous aspects require a proper control law, a model of the system is very useful for defining and tuning a control structure. Thus, after providing a functional overview of the ZCS dc/ac CSI, this paper formulates a large-signal model and then derives and simplifies the averaged one. Numerical data are used to validate the models that are obtained. An active damping control for a motor drive is defined and tuned by means of the simplified averaged model, and its effectiveness is numerically validated. Experimental results conclude this paper.