The Z-source inverter has gained popularity as a single-stage buck-boost inverter topology among many researchers. However, its boosting capability could be limited and therefore it may not be suitable for some applications requiring very high boost demanding of cascading other dc-dc boost converters. This could lose the efficiency and demand more sensing for controlling the added new stages. This paper is proposing a new family of extended boost quasi ZSI to fill the research gap left in the development of ZSI. These new topologies can be operated with same modulation methods that were developed for original ZSI. Also they have the same number of active switches as original ZSI preserving the singlestage nature of ZSI. Proposed topologies are analyzed in the steady state and their performances are validated using simulated results obtained in Matlab/Simulink. Furthermore they are experimentally validated with results obtained from a prototype developed in the laboratory. Index Terms-DC-AC power conversion, Inverters, Z-source inverter

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This paper presents new gating techniques to improve the efficiency of zero-voltage zero-current switching (ZVZCS) full-bridge DC-DC converter for battery charging in electric vehicles. The converter is assisted by a passive auxiliary circuit to extend the zero voltage switching range. The uncontrolled auxiliary circuit current increases the conduction losses of the converter when gated with conventional phase-shift modulation (PSM) technique. The controlled auxiliary circuit current with the proposed pulse-width modulation (PWM) gating techniques increases the efficiency of the converter especially at light-load conditions compared to PSM. In this paper, the steadystate analysis of the converter auxiliary circuit with the PWM gating techniques is presented. A comparative loss analysis with PWM and PSM gating techniques is also given. A 1.2-kW, 100-kHz converter is implemented on ORCAD-Pspice and the simulation results are presented to validate the improvement in efficiency of the converter with the proposed PWM gating techniques.