| Summary: | 碩士 === 國立交通大學 === 機械工程系所 === 102 === Designing in-wheel motors for electric vehicles and hybrid electric vehicles has already attracted attention in recent years. The choice of motors for both electric vehicles and hybrids is generally determined by three factors: weight, efficiency and cost. Hence, the permanent magnet brushless motors that have the lightest weight and maximum efficiency are becoming the mainstream of electric vehicle drive systems nowadays. However, based on the cost of rare earth metals of the permanent magnet consideration in the future, reluctance motors without using rare earth metals have become interesting research topics.
Switched reluctance motor (SRM) is gaining widespread interest as a candidate for electric and hybrid electric vehicle due to its simple structure, ruggedness, ability of fault-tolerance, extremely high-speed operation, high power density and low manufacturing cost. However, for vehicle applications, the disadvantages of SRM are the generation of acoustic, vibration and torque ripple. According to the literatures, the dominant source of acoustic noise and vibration are radial force produced by radial motor and axial force produced by axial motor. The unique salient pole structure of stator and rotor and nonlinear inductance contributes the higher torque ripple. This study establishes the computer-aided design process of SRM. By deriving the motor output equation and feasible triangle method, the size of SRM can be roughly decided. Then according to the analytical results of air gap permeance at aligned and unaligned position with equivalent magnetic analysis where the flux linkage curves at aligned and unaligned position can be obtained from. Furthermore, by finding out the product of current and turns which produces the maximum variation of co-energy determine the optimum current and turns. Finally, use the finite element method to verify the performance of motors.
This study also proposed a novel SRM with axial and radial air gap to make the flux flow have both radial and axial directions. The motor is hence called hybrid flux SRM. The purpose is to increase the output torque and reduced acoustic and vibration problem. The rotor of HSRM is composed of radial and axial rotor pole to lower the radial and axial force for reducing acoustic noise and vibration. The stator of HSRM is constructed by several independent C-core stators. The features of this C-cores are wound individually and automatically without complex and expensive winding equipment, low production cost, more space of motor slot and better thermal dissipation. Based on the design process which has been already established, the HSRM is designed and implemented in this study. Finally, the performance of HSRM is compared with the traditional SRM and other motors.
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