Simple Voltage Balancing Approach for CHB Multilevel Inverter Considering Low Harmonic Content Based on a Hybrid Optimal Modulation Strategy

This paper presents an effective hybrid optimal modulation technique for a cascaded H-bridge (CHB) multilevel inverter. The introduced method is generalized optimal pulsewidth modulation, which can be extended to any m-level CHB multilevel inverter operating at any switching frequency. The presented hybrid optimal modulation strategy includes the pattern exchange and optimal modulation techniques. In the optimal modulation technique, the hybrid interior-point algorithm, which is more flexible and efficient than conventional optimization techniques, is applied. The proposed hybrid optimal modulation strategy yields balanced units´ output fundamental voltages, and low total harmonic distortion without the need for additional stabilizers. The performance of the proposed modulation strategy is verified by simulation studies and experimental results using a five-level CHB single-phase multilevel inverter.