A novel isolated three-port converter with ZVS range extension and power decoupling

Abstract

This paper proposes a fixed-frequency isolated three-port converter (ITPC)that simultaneously realizes topology-level power decoupling, RMS-current minimization, and wide-range zero-voltage-switching (ZVS) extension. The main novelty is the coordinated use of an LC-resonant decoupling network, a switch-controlled-capacitor (SCC)-based equivalent-impedance regulator, and auxiliary-current injection. In contrast to existing three-port converters in which decoupling and ZVS extension are usually treated separately, the proposed ZVSRE-ITPC uses the SCC not only for power regulation but also to shift the ZVS boundary under the optimized modulation strategy. By matching the resonant frequency of each LC tank to the switching frequency, the direct power-transfer path between ports 2 and 3 is eliminated. An root-mean-square-current-minimized optimized modulation strategy (RMS-OMS) is further derived using the Karush–Kuhn–Tucker framework. Under the prototype parameters, the SCC reduces the critical ZVS power-transfer boundary of port 3%–14.63% of the original boundary, and the auxiliary inductor enables port 1 ZVS over the investigated operating range. A laboratory prototype verifies the power decoupling, RMS-OMS, dynamic transient response, efficiency improvement, and ZVS range extension.