Low-Speed Direct Drive Permanent-Magnet Synchronous Motor

The drives in low speed are often used in the aspect of autocontrol and the production of industry and agriculture, which were actualize by the system of motor and retarder or the permanent magnet inductor motor before, but both of them have many disadvantages. After the configuration of the fractional-slot winding is put forward, fractional-slot winding permanent magnet synchronous motor is use more and more in the low speed drives. This paper will introduce this special configuration in detail.Fractional-slot winding and integer-slot winding are the two important forms of motor winding. This paper will compare them in the configuration and the inductance of the winding in order to understand the configuration of fraction-slot winding. Fraction-slot winding also have the symmetry problem, that is to say, not all the fraction-slot windings are symmetry, this paper will tell you the symmetry condition, which is helpful for the design of the fraction-slot motors. The fraction-slot windings which pitch is 1 are very important, they were widely used in middle and small size motors and permanent magnet ac servo motors, this paper will introduce this winding in detail and then gave the common pole-slot match and many parameters of this windings for the analysis in future. The winding layout of fraction-slot motors is more complex than integer-slot motors in 60°phase belts, this paper will introduce two methods to solve the problem of winding layout.There are not only odd harmonics but also many even harmonics and fraction harmonics, this paper will gave the expression to identify the harmonics of fraction-slot motors and the winding factor. Cogging torque is an important problem in designing the high performance permanent magnet machines. This paper will analyze it with analytical solution and introduce some methods to reduce it.Ansoft is a common software in the designing and analysis of permanent magnet machines, this paper will use the Rmxprt which is a part of Ansoft to design motors and gain the steady parameters and performance. Then this paper will creat two-dimensional model and analyze it in Maxwell which is another part of Ansoft. At last we can get magnetic field distribution and all kinds of performance curves, which will show that the electric machine design is feasible. At last, a prototype is manufactured and a load experiment is carried out to validate its performance.