Advanced Topology, Modulation, and Control for Achieving High-Performance Solar Microinverters

Abstract

Solar microinverter systems are classified into two-stage and single-stage topologies. Two-stage designs are constrained by the poor performance of the second-stage full bridge inverter (FBI), while single-stage dual active bridge (DAB) microinverters suffer from the lack of active power decoupling (APD).

Chapter 2 proposes a DAB+FBI topology with an active auxiliary branch, achieving zero-voltage turn-on switching, fixed frequency, and continuous conduction mode (CCM) FBI operation. Simulations show a 60% loss reduction and 98.14% peak efficiency.

Chapter 3 introduces an APD modulation that reuses the primary-side DC-blocking capacitor as a decoupling capacitor with a large-signal control loop, cutting capacitor volume by 75% and input current ripple by 96%.

Chapter 4 develops a synergistic modulation extending APD to non-unity power factor. With an inner phase shift, secondary current is optimized, reducing RMS current by 27% and improving efficiency by 4.5%, reaching 93.8% full-load efficiency.

Overall, the proposed topologies and modulation strategies enhance efficiency, power density, and MPPT accuracy, advancing high-performance solar microinverter systems.