The dc voltage of the bi-directional tandem type Z-source NPC three-level inverter is divided through voltage-divider capacitor. As a result, the neutral-point(NP) potential should be kept balance. However, the NP potential balancing methods, applied to the Z-source NPC three-level inverter, have the following disadvantages: 1)unsuitable for the bi-directional converter; 2)due to the interaction between the NP potential balance and Z-source boosting as well as low boosting ability of the traditional SVPWM modulation, it is difficult to obtain the NP potential balance. In order to solve the problems, by extending the shoot-through offset, the boosting ability of the advanced SVPWM modulation is improved. What is more, combining the dynamic balance factor with Z-source boosting, the NP potential balancing methods for the bi-directional Z-source NPC three-level inverter is proposed. The simulation results indicate that compared with the traditional SVPWM modulation, the boosting ability of the novel topology is improved based on the advanced SVPWM modulation. In addition, the NP potential is obtain balance in following 3 operations, including inverter, rectifier and low power factor operation.
