Pulse Energy Modulation for a Single-Phase Bridge Inverter With Active Power Decoupling Capability

Single-phase voltage-source bridge inverters are widely used in energy storage systems (ESS) and distributed energy resources to transfer dc power to grid-side ac power. The most popular modulation strategy for controlling the ac output of bridge inverters is known as carrier-based pulsewidth modulation (PWM), which varies the duty cycle of the inverter switches at a high switching frequency to achieve a target average line-frequency output voltage or current. Regarding most carrier-based PWM techniques only enable the bridge inverters to operate under continuous conduction mode (CCM) due to the nonlinearity of discontinuous conduction mode (DCM), a pulse energy modulation (PEM) technique is proposed in this article to control single-phase bridge inverters based on energy packets, enabling the inverter to operate under both DCM and CCM and switch between them seamlessly. A single-phase bridge inverter with voltage boosting and power decoupling capabilities is examined as a case study. Small-signal analyses have been conducted for the inverter system with both L-filter and LCL-filter, and the resonant spike of LCL-filter is attenuated in PEM. Simulation and experimental results verify the feasibility of PEM on the investigated single-phase bridge inverter under both DCM and CCM.