Fully Digital BCM ZVS Hybrid Control for a Single-Phase Islanded Mode DC/AC Inverter

This article proposes a method for implementing a single-phase islanded mode DC/AC inverter with a combination of unipolar modulation and bipolar modulation without detection of high-frequency current under boundary conduction mode (BCM). The strategy proposed in this article does not require sampling the zero-crossing and boundary values of high-frequency currents. Instead, a feedforward voltage and current double closed-loop is introduced to control the switch of the high-frequency switching leg. The control strategy in this article can operate stably for loads with arbitrary power factors, and there is no need to adjust the control strategy and parameters. The modulation strategy adopts a combination of unipolar and bipolar methods to improve the output voltage total harmonic distortion of nonunit power factor loads. A 300 W single-phase inverter prototype was established to verify the feasibility and effectiveness of the control strategy.