ZVS Turn-on Triangular Current Mode (TCM) Control for Three-Phase Two-Level Converters With Reactive Power Control

Abstract

High switching frequency operation in power converters leads to a significant reduction in size at the cost of increased switching losses. Thus, soft switching techniques become necessary to reduce the losses. WBG devices have the benefit of low turn-off losses, but the turnon losses are still significant. Triangular Current Mode (TCM) control can achieve zero voltage switching (ZVS) turn-on without adding extra resonant components or active devices to the converter. For three-phase operation, soft switching, sinusoidal currents, and phase synchronization are achieved by operating the phases in a combination of Discontinuous Conduction Mode (DCM), TCM and clamped mode. This method is extended to reactive power cases in this paper. The proposed scheme can achieve full ZVS turn-on for all the three phases. The phases still operate in a combination of DCM+TCM+Clamped modes of operation. The proposed algorithms are tested and validated on a GaN converter, achieving 99% efficiency at 700 VA with a power density of 110 W/in 3 .