Analysis of Cooling System and Its Influence on Magnetic Flux Density in a Motor

Abstract: After Michael Faraday invented the magnetism theory in 1821, the application of the permanent magnet machine was rapidly developed. The permanent magnet synchronous machine is one of the popular applications of electromagnetic theory, which is implemented in most electric vehicles nowadays. Since then, the trend of renewable electricity increased in order to reduce emission and electric vehicle popularity increased significantly. However, designing a motor that is able to rotate very fast for electric vehicle implementation is tricky. The cooling part is one of the important parts in order to achieve maximum performance of the motor.  The power produced by the motor is related to the total induced voltage of the motor, while the magnetic flux is one of the key factors in order to achieve higher induced voltage. On the other hand, the magnetic flux is inversely proportional with the temperature, the magnetic flux density decreases as the temperature increases. In order to design a motor for electrical vehicle, cooling system design is one of the important thing to consider. The motor and cooling system design was built and studied using Comsol software, with the Finite Element Method (FEM) method used to analyse the model. Two cooling systems implemented in COMSOL Multiphysics were the water cooling and air cooling system. The air cooling is represented by a fan located above the motor, the flow of the air analyzed using a turbulence flow physics. The water cooling system designed as a pipe goes around the motor as a helix, the water flow inside the pipe analyzed as a laminar flow. The simulation also involves the heat transfer physics in solid and fluid considering the convection and conduction heat transfer. The result of the simulation showed the temperature distribution in the motor after two cooling systems implemented, the water and air cooling. The cooling system helps to reduce the temperature around the magnet in order to increase the torque of the motor by providing high magnetic flux and induced voltage in the stator winding. The temperature around the magnet decreased significantly after both cooling systems were implemented, in result the performance of the motor remained high. However, the simulated model is modified from the comsol tutorial model which does not really describe a permanent magnet machine.