A Soft Mode Transition Method for Dual-Active-Bridge Microinverters with Adaptive Mode Boundary Conditions

作者：Minseok Kim, Suyong Chae · 发表于：2026 International Power Electronics Conference (IPEC-Nagasaki 2026 - ECCE Asia) · 年份：2026 · DOI：10.23919/IPEC-Nagasaki2026-EC64663.2026.11596698

This paper proposes a soft mode transition method for a dual-active-bridge (DAB) microinverter to extend practical zero-voltage switching (ZVS). As the AC grid voltage varies, a single modulation mode cannot maintain ZVS over the entire operating range. Under such conditions, mode transitions are required but mismatched initial secondary side currents between modes lead to transient current oscillations. To address this problem, this paper presents a mode transition method that determines the transition boundary based on the voltage conversion ratio and aligns the secondary side current during mode changes. A simple switching-time adjustment with a short secondary side freewheeling interval enables a smooth current transition. The proposed method mitigates transient oscillations during mode transitions. Its effectiveness is validated through simulations and experimental results obtained from a 350-W microinverter prototype.