Research On Starting Performance Of Line Start Permanent Magnet Synchronous Motor

Compared to induction motors, permanent magnet motors have advantages of high power factor, high efficiency, small size and wide operating range, because of rich reserves of rare earth resources in our nation, the development conditions of rare earth permanent magnet motor are sufficient, so in recent years, permanent magnet motors has been developed enough to replace induction motor. Different with induction motor, permanent magnet synchronous motor can not be started by itself, it needs to be controlled by drive circuit before running smoothly; however, line-start permanent magnet synchronous motor not only inherits the advantages of permanent magnet synchronous motor in the steady-state operation, and because of the presence of the rotor winding, it has the ability of self-starting just like induction motor. Therefore, this kind of motors do not need the expensive motor drives and sensors for precise control applications, and has been gradually promoted and applied in the industry field, more and more attention has been paid by research experts and scholars. But what’s different with the induction motor is that the rotor of self-starting permanent magnet synchronous motor has start winding and permanent magnets simultaneously, on the one hand, the rotor design space is limited; on the other hand, it also makes the motor more complicated. To obtain optimum starting performance, we need to study the starting performance of this motor thoroughly.Firstly, the starting process of line-start permanent magnet synchronous motor is analyzed theoretically, and affects of different parameters of slot number, slot type and slot depth to starting performance of motor are studied; moreover, starting performance change rules of motor in the different rotor slot parameter are concluded.Secondly, motor starting performance in different materials on the squirrel cage were studied primarily from a single squirrel cage materials and composite structures cage: in single squirrel cage material part, starting performance by using cast aluminum, aluminum, brass, bronze and copper is analyzed; composite structure cage part mainly study starting performance under various combinations of aluminum and copper; in the end, optimal solution and conclusion are reached.Thirdly, optimal motor starting performance of squirrel-cage design under different power is studied on the basis of the 18.5k W motor. 11 k W, 15 k W and 22 k W motor models are established respectively, and the squirrel cages of these three types of power are optimized; after that, the relationship between the squirrel cage design parameters and motor power is summed up and corresponding empirical formulas are concluded.Fourthly, different starting methods for permanent magnet synchronous motors are studied, mainly starting performance of solid rotor and conductive sleeve type are analyzed, taking into account the added squirrel cage solid rotor and a conductive sleeve plus squirrel cage motor starting performance; and further, starting performance of single solid rotor and single conductive sleeve type is concluded.Finally, 7.5k W line start permanent magnet synchronous motor is tested and analyzed by FEM. simulation analysis is conducted on the motor and relative starting performance parameters and curves are achieved; after that, the cage of the motor is optimized according to the former conclusion about cage optimization, meanwhile, no load starting and load starting simulation are analyzed, by comparing with original case, we come to the conclusion that starting performance of new design case is improved; then No load experiment and load experiment are mainly conducted on the motor, by comparing simulation results with experiment results, the correctness of experiment results is verified.