新型Z源不对称三电平逆变器及中点电位控制方法研究

为克服单Z源中点箝位型NPC(neutral point clamped)三电平逆变器主电路所需器件多、硬件成本高的缺点,提出了一种新型Z源不对称三电平逆变器拓扑结构,该拓扑不需要箝位二极管,同时保持了Z源三电平逆变器的固有优势。根据其特有的上、下直通状态插入规律以及对中点电位的影响,提出一种最优空间矢量脉宽调制SVPWM(space vector pulse width modulation)控制策略,通过调节上、下直通时间,在实现直流升压的同时有效抑制了中点电位的偏移,且最大程度减小了直通动作产生的开关损耗。通过MATLAB/Simulink仿真,验证了该方法的可行性和有效性。

Research on Novel Z-source Asymmetric Three-level Inverter and Neutral-point Potential Control Method

The main circuit of a single Z-source neutral-point-clamped(NPC) three-level inverter requires numerous elements, which results in higher hardware cost. To overcome these disadvantages, a novel topological structure of Z-source asymmetric three-level inverter is proposed, which does not need any clamp diode while maintaining the inherent advantages of Z-source three-level inverters. According to its unique insertion laws of upper and lower shoot-through states as well as its influence on the neutral-point potential, a kind of optimal space vector pulse width modulation(SVPWM) control strategy is proposed. By adjusting the upper and lower shoot-through time, the novel inverter not only maintains the desired boosted DC output voltage, but also effectively restrains the offset of neutral-point potential; meanwhile, the switching loss resulting from the shoot-through action is reduced to a maximum extent. Through simulations in MATLAB/Simulink, the feasibility and effectiveness of the proposed method is verified.