Improving the DC-Link Utilization of Nine-Switch Boost Inverter Suitable for Six-Phase Induction Motor

Nowadays, multiphase induction drives are used in electric vehicle applications to improve reliability and efficiency. These induction motors are controlled by using a multiphase voltage-source inverter (VSI). As the number of phases increases, the number of switching devices used in multiphase VSI also increases, which results in a reduction of the system efficiency and an increase in the cost. Among these multiphase drives, the six-phase drive is used more frequently in electric vehicular industries. A conventional six-phase VSI requires 12 switches to drive the six-phase machine. Also, conventional six-phase VSI requires more dc-link voltage than the boost six-phase VSI to drive the six-phase machine. In order to overcome the problems associated with the conventional six-phase VSI-controlled six-phase induction drives, this article proposes a nine-switch boost inverter (NSBI) for six-phase induction drive applications. The proposed NSBI has a single-input dc voltage source, and it provides six-phase ac output voltages. These six-phase output voltages are regulated by using modified nonsinusoidal pulsewidth modulation (MNSPWM) technique. The proposed NSBI with a six-phase induction motor is simulated using MATLAB/Simulink and validated using a field-programmable gate array (FPGA)-controlled hardware prototype. The verification of the proposed system during load-torque variations and winding-failure conditions is carried out.