The Design And Analysis For 18/12 Pole External Rotor Doubly Salient Permanent Magnet Wheel Motor

In recent years, with the continuous improvement of people’s living standard, Automobile demand is developing very rapidly. According to relevant data of China Automobile Industry Association, in 2015 China auto sales reached Twenty-four million five hundred and ninety-seven thousand and six hundred units. The contradiction between the development of automobile industry and energy and environment is becoming more and more serious. Traditional car is mainly fuel vehicles, energy consumption direct cause environmental pollution and it is also the main cause of global oil crisis. under the pressure of environmental protection and energy crisis, governments, research institutions and automobile manufacturers have to invest a lot of manpower and financial resources to develop new high-performance and environmentally friendly zero-emission electric vehicles. However, as one of the key technologies in the research of electric vehicle, the wheel motor technology is expected to become the main force of electric vehicles in the future.based on the rotor type, Wheel motor drive system is mainly divided into two kinds of structure: External rotor motor and outer rotor motor. External rotor motor is usually a low speed external motor, the maximum speed of it reach 1000-1500 r/min, it have not reduction gear, The speed of the wheel is the same as the motor; While the inner rotor motor is usually a high-speed internal rotor motor, and equipped with fixed transmission ratio of gear reducer. in order to obtain high power density, the speed of the motor is up to 10000 r/min.Based on the standard of reference for automobile wheel hub and a large number of documents, the paper designed an excellent outer rotor 18/12 pole doubly salient permanent magnet wheel motor. Doubly salient permanent magnet motor is developed on the basis of the switch reluctance motor, it obstains the advantages of switched reluctance motor and permanent magnet motor, Compared with the former two kinds of motor, its characteristic has the relative superiority, therefore, it has a broad space for development.This article first introduces the research background and development status and trend of automobile motor, which focuses on the research status of doubly salient permanent magnet motor, and points out key points of the research on wheel hub motor, such as motor ontology design, rotational pulsation suppression, weak magnetic control. And this paper simply describes the operating principle and mathematical model of switched reluctance motor, based on it,the paper introduced the mathematical model of doubly salient permanent magnet motor and operating principle. Then taking a Honda car as an example, this paper introduces the selection of motor rating data, the selection of pole number and the number of phase, the selection of the stator size, the selection of the rotor size, the selection of the size of the permanent magnet,the selection of various parts of the motor. Next, this paper focuses on the finite element analysis of the motor. It mainly includes no-load analysis and load analysis. No-load analysis mainly includes the lines of magnetic force analysis., magnetic field intensity analysis and magnetic chain analysis. It also verify the rationality of the motor design through the no-load analysis and it derives the turn-on sequence and the conduction interval of the switch tube of the drive circuit through flux linkage analysis.The load analysis mainly includes the analysis of the torque and mechanical characteristics. Through the torque analysis, the method of reducing the rotation pulse is analyzed. The suitable operating speed range of the electric vehicle drive motor is obtained through the analysis of mechanical characteristics. Next,compared 18/12 pole and 12/8 pole doubly salient permanent magnet motor in the ontology structure, power density and rotation pulse,It shows the performance superiority of 18/12 pole doubly salient permanent magnet motor. Finally, this paper summarized the process of the designed motor, And the part which does not involve in the process of the design is given a simple outlook. It pave the way for future research of the motor.