Novel Improvement Strategy for the Thrust of Linear Induction Motor Using Modified Ladder Slits

五电平PWM逆变器具有许多优点，例如能够以接近正弦的电流波形操作电机或静止无功补偿器（SVC）。由于这些原因，对申请的实际审议才刚刚开始，人们对此很感兴趣。在应用的讨论中，还期望更大容量的逆变器。为了提高开关器件的容量，提出了五电平PWM逆变器并联的技术和控制方法。然而，在高功率应用中，载波应与调制正弦波同步。此外，每个三相波形应该以每个半波的双边对称以及水平轴对称来构建。此外，对于均流电抗器，禁止应用低阶谐波。为了改善三相五电平逆变器并联系统的谐波特性，设计并讨论了各种调制策略。

The five-level PWM inverters have many advantages such as an ability to operate the motor or the static var compensator (SVC) with nearly sinusoidal currenl waveforms. For these reasons, actual consideration of applications have just begun with great interest. In the discussion of applications, still larger capacity inverters are also expected. In order to increase the capacities of switching device, a certain technique and controlling methods are proposed for the parallel connections of the five-level PWM inverters. In high-power applications, however, the carriers should be synchronized to modulating sinusoidal waves. In addition, each three phase waveform should be built in a bilateral symmetry for each half-wave as well as the horizontal axis symmetry. Moreover, for the current sharing reactor, lower order harrnonic application is prohibited. To improve the harmonic characteristic of the parallel connected three phase five-level inverters, various modulation strategies are devised and discussed.