An Improved Pulse Width Modulation Strategy for Cascaded Single-Phase High-Frequency Link Matrix Converter

Single-phase high-frequency link matrix converters (SPHFLMC) are widely used in renewable energy grid integration scenarios due to their advantages of compact size, bidirectional energy flow, high efficiency, and high-frequency isolation. To increase the capacity of the system and reduce the voltage stress on power electronic devices, it is necessary to cascade the SPHFLMC. However, traditional modulation strategies suffer from severe difficulties including high Total Harmonic Distortion (THD) of the output voltage on the AC side and power imbalance between the cascaded modules. To address these issues, this paper proposes an improved Level-Shifted Pulse Width Modulation (LS-PWM) strategy for cascaded SPHFLMC. Firstly, the cascaded matrix converter (MC) modules are decoupled, and the corresponding modulation princi-ples and switching logic are designed. Then, the dwell time of each module is reallocated. Finally, the simulation results indicate that the LS-PWM strategy can significantly reduce the AC-side output line voltage THD while achieving power balance across the modules, when compared with the traditional modulation strategy.