混合七电平逆变器的变频调速PWM控制策略

该文提出了基于参考电压分解的多电平直接PWM算法,分析并给出了该直接PWM算法在混合七电平逆变器中的应用方法,给出了主逆变器及辅助逆变器开关频率与控制频率的关系;通过仿真对混合七电平逆变器的直流电压平衡问题进行了研究,得到了不会出现直流电压不平衡的PWM开关模式;分析并提出了一种适用于混合七电平逆变器的改进的死区效应补偿方法,研制了一台基于混合七电平逆变器的交流380V变频调速实验样机.实验结果验证了混合七电平直接PWM算法及改进的死区补偿方法的有效性和正确性.

VARIABLE FREQUENCY DRIVE PWM CONTROL STRATEGY FOR HYBRID 7-LEVEL INVERTER

This paper proposes a multilevel direct PWM control strategy based on reference voltage decomposition, analyzes and gives the application of the proposed strategy in hybrid 7-level VSI. Relationship between switching frequency of individual switching component and the control frequency is given. Possible DC voltage unbalance is studied through PSCAD simulation and the appropriate modulation mode is obtained. The dead time effect of hybrid 7-level inverter is analyzed and a modified compensation method is proposed. An experimental drive system based on hybrid 7-level inverter is developed. Various experimental results demonstrate the validity of the proposed PWM control strategy and the modified dead time compensation method.