Cascaded Multilevel Rectifiers with Reduced Number of Controlled Switches for Open-End Winding PMSM

Abstract

This paper proposes three configurations of unidirectional open-end winding (OEW) cascaded multilevel rectifiers with reduced number of controlled switches. They are based on Vienna rectifiers and are composed of a series combination of two three-phase converters and three H-bridges employing floating capacitors (per phase). These configurations make the ac-dc conversion power, supplied by a permanent magnet synchronous machine (PMSM), which is connected to the rectifier by an OEW configuration. Compared to the conventional, proposed systems synthesize the same or higher number of voltage levels using fewer number of controlled switches and is still possible to obtain lower converter current harmonic distortion. Furthermore, they can operate with lower switch blocking voltage ratio. These features make them attractive options to the industry due to their low costs, low control complexity and size, besides they are more reliable and less prone to failure. Therefore, proposed configurations have a better cost-benefit than conventional one. The system model, PWM technique, capacitor voltage balancing and control strategy are given. Simulation and experimental results are provided in order to validate their feasibility.