Adaptive reverse current control and voltage equalization strategy for T-type BCM Microinverter

Abstract

This paper proposes a voltage equalization modulation strategy and an adaptive reverse current control method for the single-phase T-type boundary conduction mode (BCM) micro-inverter. The T-type converter uses multi-level technology to solve the problem of high frequency of traditional full-bridge BCM micro-inverter under light load conditions. But it also brings the problem of DC-side capacitor voltage unbalance. The proposed voltage equalization modulation strategy ensures that the converter is balanced at the midpoint of the DC side under BCM operation. The adaptive reverse current control method ensures the realization of zero-voltage switching (ZVS), and zero-current switching (ZCS) can be additionally realized by setting a smaller ZVS margin constraint. This control method also restricts the frequency to avoid various losses and electromagnetic interference caused by excessively high switching frequency under light load conditions. In order to verify the proposed control method and the implementation of ZVS, a single-phase T-type BCM micro-inverter was simulated based on MATLAB / Simulink.