A Hybrid Boundary Conduction Modulation for a Single-Phase H-bridge Inverter to Alleviate Zero-Crossing Distortion and Enable Reactive Power Capability

摘要

Boundary conduction mode (BCM) featuring zero-voltage switching has caught researchers' eyes recently. In single-phase full-bridge inverter with one leg operating in high switching frequency and one leg in line frequency, it is easy to achieve high conversion efficiency for low-power applications. However, severe distortion will be introduced during zero-voltage crossing area due to too low switching frequency around this area, and reactive power generation is not allowed under this modulation scheme due to zero-voltage crossing issue. This article proposes a hybrid BCM strategy for a single-phase full-bridge inverter to both alleviate voltage zero-crossing distortion and enable reactive power generation by reshaping the triangular waveform of inductor current into quadrangle waveform through rearranging the driving signals during voltage zero-crossing area. This alleviates zero-crossing distortion by avoiding too low switching frequency and enables reactive power generation by employing the hybrid BCM around voltage zero-crossing area. High efficiency can be maintained by combining the proposed hybrid BCM employed only for a small portion of zero-crossing area and the conventional BCM for the rest. The principle of operation, theoretical analysis, and simulation results are presented in this article. A 300-W microinverter prototype was built to verify the feasibility and effectiveness of the proposed hybrid BCM scheme.