Indian Journal of Science and Technology

Abstract

We investigate the effectiveness of GaN FETs to reduce the switch losses in the motor driving system for electric wheelchairs. In general, the three phase inverter is used as the circuit topology for the motor driving system, and it has the six power semiconductor switches based on the silicon such as IGBT and MOSFET. As a method for the reduction of the switch loss including the reverse recovery loss, we replaced the MOSFETs with the GaN FETs, because the GaN FETs have the electric performance improvements over their silicon counterparts. To verify the superiority and effectiveness of GaN FETs, the motor driving systems with GaN FETs and MOSFETs were analyzed and compared by the PSIM simulator. In the simulation, the calculated switch loss of a MOSFET and a cascode GaN FET for the 830W motor driving system is 0.327W and 0.074 W, respectively. The GaN FET had the 4.4 times lower switch loss than the Si FET. Therefore, the effectiveness of the GaN FET for reducing the switch loss is proved from the simulation results.
Keywords: Electric Wheelchair, FET (Field Effect Transistor), GaN (Gallium Nitride), Motor Driving System, Rehabilitation