Design And Analysis Of Multi-unit Outer-rotor Permanent Magnet Machines

The ever-advancing time addresses the safe and efficient use of energy and sustainability of our environment.Electric drive system and its related industries have seen rapid development.The electric drive system is a key technology in the fields of electric vehicles,multiple electric aircrafts,and ship drivers,etc.To these applications,improving system output is the most important goal.In addition,there are certain requirements on the system security,which means that the drive system needs to have high reliability.Outer rotor hub motor system avoids bulky mechanical structure while multi-unit motor system boosts electrical integration,both of which have attracted extensive attention in recent years.In this thesis,combining the characteristics of the above two motor types above,the outer rotor multi-unit fault-tolerant interior permanent magnet synchronous motors(MOFTIPMM)with low speed and high torque output are studied for pure electric vehicles(PEVs)wheel drive.The research mainly includes the following aspects:Firstly,the power equation of outer rotor motors deduced.Based on the basic working principle and application requirements,the rated design parameters were determined,and the design flow was clarified.Secondly,5 slot-pole combinations are discussed.Through reasonable scheme selection,the motor can achieve better output and fault tolerance performance.On this basis,a V-shape permanent magnet outer rotor is designed in 24-slot/20-pole design.The differences in inductance,steady-state electromagnetic torque and no-load back EMF are investigated between the VPM and surface-mounted PM(SPM)motor.The advantages and disadvantages of the VPM motor are stated.Then,slot displacement design for stator optimization in fractional-slot concentrated winding(FSCW)is explored.Results cover both single and double layer winding types where the tank electromotive force of the star chart is provided as a solid theoretical support.On this basis,a parametric model of a MOFTIPM motor was built.Taking torque,ripple,and unit permanent magnet torque output as performance indicators,multiple variables are selected to optimize the motor design.Through response surface method(RSM),the sensitivity of the structural parameters under different performance indexes is given.The loss and efficiency of the optimized motor are calculated to verify the design.Finally,the steady-state thermal field of the optimized design is calculated with 3D motor model.The temperature distribution includes the stator,rotor,armature windings and permanent magnets,etc.The results further validate the motor design.