AC small signal modeling, analysis and control of quasi-Z-Source Converter

This paper addresses the ac small signal modeling of the quasi-Z-Source Converter (qZSC). The linearized control/disturbance-to-system-variable transfer functions of the voltage-fed type quasi-Z-source network are derived, indicating the existence of right half plane (RHP) zero, which could impose limitation on controller design. Analysis on the dynamics introduced by the shoot-through state of the quasi-Z-source network is presented based on the ac small signal model, which is compared with the detailed circuit model for validation. Considering system dynamic characteristics, the qZSC design guidelines for passive component sizing is investigated by parameter sweeping of the small signal model based transfer functions. As another application of the ac small signal modeling, a PI compensator with feed forward control loop is developed for the qZSC in stand-alone operation. Experimental result is provided to validate the effectiveness of the closed-loop control.