多电平最优空间矢量PWM控制方法的研究

空间矢量PWM控制方法已在常规二电平板式逆变器广泛应用，而由于电平数增多，采用常规的空间矢量调制方法从数以百计千计的矢量中选取合适的矢量非常困难，因此多电平变流器的控制只用于电平数目较低如三电平、四电平或五电平。该文提供了一种新型的用于多电平变流器的多电平最优空间矢量PWM控制方案（MOSV PWM）。这种控制方法基于空间矢量PWM控制的思想，从三相参考电压得到8个待选空间矢量和参考电压矢量，然后选择与参考电压矢量最近的空间矢量。这种方法微机执行时间短且执行时间与电平数目无关，不受电平数目增加的影响，还可以与最优开关频率PWM法同时使用以提高调制系数。采用异步电动机调速系统对这一方法进行了验证。

INVESTIGATION ON MULTILEVEL OPTIMAL SPACE VECTOR PWM CONTROL TECHNIQUE

Space vector PWM technique has found a wide application in conventional two level bridge inverters, however it has found few applications in multilevel converters except for the low number of levels for example three ,four or five levels, because it becomes very difficult to choose the appropriate vector from hundreds or thousands of vectors with the increase of the number of levels by means of conventional space vector modulation techniques. This paper presents a novel Multilevel Optimal Space Vector PWM (MOSV PWM)control scheme for multilevel converters. The proposed control technique, based on space vector control theory , generates eight space vectors to be chosen and the reference space vector from the three phase voltage reference signals, and then chooses the space vector nearest to the reference space vector . The MOSV PWM technique requires constant execution time independent of the number of the voltage levels and can be applied in combination with SFO PWM technique to increase the modulation index. By means of a sensor less induction motor speed regulation system the proposed technique is verified by simulation results.