Optimization Design And Analysis Of Dual-rotor Permanent-magnet Fault-tolerant Motor With High Power Density

This paper investigates of a novel kind motor of dual-rotor permanent-magnet fault-tolerant synchronous motor(DRPMSM), which not only owns the advantages of dual-rotor permanent-magnet ynchronous motor with high power density and high efficiency, but also has high fault tolerance. So these characteritics make it more appropriate for using in marine electrical propulsion, aerospace and electric vehicles(EVs). Considering the urgent requirements of electrical drive systems for high power density motors in different fields.The electromagnetic, thermal and mechanical characteristics of DRPMSM are mainly investigated in this paper, as follows:Firstly, the special structure and working principle of dual-rotor permanent-magnet machine are introduced. It can be seen as the synthesis of double motors. In order to bulid the motor models quickly, the designing process of DRPMSM is introduced.Secondly, the cogging torque of motor is analyzed and the optimal pole arc coefficient model is introduced. Towards five different power levels machines, the length to diameter ratio of motors is selected to optimize the highest power density, the effect on electromagnetic characteristic for different power levels machines is given and the principles of choosing the optimal split ratio is obtained.Thirdly, the heat sources of different power levels machines including iron loss, copper loss and permanent magnet loss are calculated. The three-dimensional temperature field models are estabilished. The coefficient of heat transfer for different parts of motor is calculated. The thermal characteristics are researched under natural condition and forced-air cooling condition with different wind speeds, the changing rules are obtained.Fourthly, considering the cantlever structure of stator, there is a strong attraction between stator and rotor. This force will induce deformation of stator. The radial electromagnetic force of different power levels motor is calculated. In addition, the mechanical characteristics are analyzed under no-load and different loads conditions, respectively.Finally, a prototype DRPMSM with rated power of 1k W is manufactured to validate the simulation results. A large number of characteristics for the prototype are tested, which contain the electrical parameters, no-load/ load and thermal experiments. Experimental results were shown to math well with the analytical results, which validated the theory successfully, which can provide a good reference toengineering application.