A Novel SVPWM Scheme for Field-Oriented Vector-Controlled PMSM Drive System Fed by Cascaded H-Bridge Inverter

In the motor drive system fed by multilevel inverter, the problems such as the complexity of reference voltage synthesis, high common mode voltage (CMV), and high switching loss are usually the obstacles to the practical application. In order to reduce the computational complexity and improve the performance of permanent magnet synchronous motor (PMSM), a novel space vector pulsewidth modulation scheme, which is practical and independent of level number is proposed for PMSM vector control. First, the space vector plane is redivided, and the coordinates of the nearest three vectors and their duty cycles can be obtained directly by determining the location of reference vector, which simplifies the calculation and does not need any iterative algorithm. Then, the optimal switching state and switching sequence are selected online so as to ensure the minimum switching loss under the premise of minimum CMV. This article provides an original method and new idea for motor drive system fed by multilevel inverter. Finally, the practicability and validity of the proposed method are verified by simulation and experiment.