三电平T型逆变器开关控制策略研究

Switch Control Strategies of Three-level T-type Inverter

多电平逆变器的应用已越来越广泛,并开始从中压高功率场合转向低压场合。近年来提出的三电平T型逆变器由于其适合低压场合工作的特点,受到很多关注。分析了该逆变器常见的开关控制策略M_(1)和M_(2),其中M1开关控制策略来源于NPC逆变器,稳态工作时的驱动逻辑比较复杂;M_(2)开关控制策略在M_(1)的基础上进行了简化,但是其暂态工作过程中会造成相关二极管的反向电流增大。为了解决上述两种开关控制策略的问题,在控制策略M_(2)的基础上对某些特定的开关器件开通、关断时间进行了调整,提出了一种新的开关控制策略M_(3)。对提出的新控制策略进行了仿真分析,结果验证了理论的正确性。

Multi-level inverters are more and more widely used and begin to shift from medium-voltage high-power applications to low-voltage applications. The three-level T-type inverter proposed in recent years has attracted much attention because it is suitable for low-voltage applications. The common switch control strategies M_(1) and M_(2) of the inverter are analyzed. The M_(1) switch control strategy is derived from the neutral-point-clamped(NPC) inverter, and the driving logic is relatively complex during steady-state operation.The M_(2) switch control strategy is simplified on the basis of M_(1). However, during its transient operation, the reverse current of the related diodes increases. In order to solve the problems of the two switch control strategies mentioned above, a new switch control strategy M_(3) is proposed. On the basis of the switch control strategy M_(2), the on-time and off-time of some specific switch devices are adjusted. The proposed new switch control strategy is simulated and analyzed, and the results verify the correctness of the theoretical analysis.