Adaptive Soft-Switching Control of Active-Clamping Three-Phase Inverters

Energy stored in the resonant inductor is critical to the zero-voltage switching (ZVS) of power semiconductor devices in soft-switching active-clamping three-phase inverters. Traditionally, the soft-switching pulse width modulation (PWM) timing parameters are designed based on the calibrated data table. However, for motor drives or general-purpose ac power supplies, their fundamental output amplitude and frequency may vary, which makes the control of the soft-switching inverter complex. It would be time-consuming and tiring to manually calibrate soft-switching timing control parameters under various operation conditions. In this article, an adaptive soft-switching control of active-clamping three-phase inverters is proposed. The resonant inductor energy storage is adjusted to the optimal value automatically. Principles and implementation of the control are introduced. Parameters design of the adaptive control is discussed. Finally, the proposed method is verified by experiments.