Simplified Zero-Voltage-Transition Circuits Applied to Bidirectional Poles: Concept and Synthesis Methodology

This paper proposes the concept and the synthesis methodology of simplified zero-voltage-transition (ZVT) circuits applied to bidirectional pulsewidth modulation poles. The main goal of simplified ZVT circuits is to make possible the use of conventional modulation schemes to accomplish better converter performance and to eliminate the synchronous-switching requirements imposed by ZVT integrated multipole topologies. To derive the simplified ZVT circuits, a synthesis methodology is proposed based on the generalization of the ZVT technique, where the restrictions to achieve the zero-voltage switching for the main converter switches are identified. Thereafter, a set of simplified semiconductor switches composed by only one high-frequency switch is defined to be used in the simplified ZVT auxiliary circuits. Thus, using the proposed synthesis methodology, any simplified ZVT topology can be derived, whether or not they have appeared in a previous publication. In order to validate the proposed approach, experimental results for a three-phase ZVT inverter, employing the minimum-loss space vector modulation and operating at 1.5 kW and 20 kHz are presented. The prototype presented an efficiency of 98% at full load representing an improvement of 0.5% when compared to its hard-switched counterpart and 1.8% when compared to an integrated ZVT topology.