A Weighted Hybrid Modulation Strategy of Single-Phase Full Bridge Inverter for Reducing Common-Mode Interference

The unipolar modulation is widely applied to the single-phase full bridge inverter for its superior performance in the output harmonic characteristics. However, it will bring serious common-mode interference so that a common-mode filter is required. Due to the nonideal factors of the practical operation condition, the actual performance of the designed common-mode filter is often inferior to that of the ideal case, which further brings EMI problems. To improve the performance of the common-mode filter, the parameters should be redesigned, and tested in an iterative way until it adapts to the practical operation condition, which is time-consuming and also increase the cost since the hardware should be changed to modify the parameters. To address this problem, a novel weighted hybrid modulation is proposed to improve the performance of the common-mode filter without replacing the hardware of the common-mode filter. The proposed weighted hybrid modulation strategy blends the bipolar into unipolar modulation and compromises the merits of both. By improving the common-mode noise, the EMI can be easily reduced to the standard level. The double Fourier analysis method is conducted to analyze the characteristics of the proposed modulation strategy. Both simulation and experimental results are presented to prove the effectiveness of the proposed method.