The performance comparison of the SiC and Si Mosfets used in 3-phaze brushless DC motor drivers for electric vehicles

Electric vehicles consist of motor, motor driver and battery systems. Since the battery capacity is limited, the system must work efficiently. The power semiconductors in the motor driver structure are important for the efficiency of this system. This effect varies according to the operating temperature and power ratio of the systemThis study is to reveal which of the SiC (Silicon Carbide) and Si (Silicon) Mosfets used in a Brushless DC Motor driver to be used in the electric vehicle structure is advantageous in terms of performance on the system. While carrying out this study, a simulation program was needed, in which the system should be tested at different powers and different temperatures. After the researches, it was decided on the PSIM application in order to ensure the accuracy of the tests and the results of the experiments to be easily observed. The system was created on this program and the results were compared after the experiments. In the study, the system was used identically, except for the power semiconductors in the structure of the motor drivers. The results were obtained by comparing systems with different Mosfet structures at different loads and different ambient temperatures. As a result of the experiments, while Si and SiC Mosfets were almost not different in the idle state of the engine, differences were observed as the mechanical load and temperature values started to increase. When the temperature conditions are examined, it has been observed that Si Mosfets are heated up to 22% more than SiC Mosfets. During the high current operation of the Mosfets, it was observed that the switching speeds of the Si Mosfets slowed down, while the SiC Mosfets were not affected When compared in terms of power loss, Si Mosfets lost 226% more power than SiC Mosfets due to more heating and slower switching speed. As a result, it has been observed that SiC Mosfets work significantly more efficiently in identical systems than Si Mosfets.