Optimized Balance Factor assited Neutral-point Voltage Balance for Three-Level T-Type Inverter

The three-level T-type inverter features multiple-level outputs and low harmonic content, making it suitable for applications with high power and performance requirements. However, due to the inherent defect in the topology of the three-level T-type inverter, this type of inverter is prone to the issue of neutral-point voltage imbalance. Traditional modulation strategies aimed at addressing this issue are often limited in their practical application to resistive loads, leading to the limitations in these strategies. A neutral-point voltage control method based on optimized balance factor is proposed by analyzing the role of basic vectors. This method utilizes the phase current corresponding to the small vector as a correction factor, separating the influence of small vector current on the potential. By combining the correction factor with the balancing factor, the feedback signal is employed in the specific working conditions of the small vector, thereby simplifying the control complexity. According to the results of simulation experiments, the method proposed can restrict the deviation of the neutral-point voltage to within 0.5V less than 6ms, and it is also applicable to resistive and inductive load conditions, demonstrating its correctness and effectiveness.