| The induction motor is the important power supply of industry and agriculture, but some time the rated power could not match with load, so the energy waste was making. Based on the existing problem the idea of designing multi-power induction motor was performed. The multi-power induction motor can change its output power according to the loading variation, and it can do some help for energy saving.The realized programme was proposed firstly in this paper, and the different output powers can be changed through altering the connection of stator windings in order to adapt to the different requests of loadings. According to the theory of electromagnetic field the 2-D mathematical model of multi-power induction motor was established. Then the starting parameters and running parameters, such as starting torque and starting current and efficiency and so on, were calculated using finite element method (FEM), the calculation results then compared with experimental results. According to the theory of time-step finite element method, the equations of time-step FEM coupling field and circuit in the solution region were established, and the starting performances at different rated loadings of multi-power induction motor were simulated and analyzed. In addition, based on the theory of heat transfer, the two-dimensional steady thermal field model is developed and the corresponding functional equation and equations of variation are derived. Then the stator windings heat conductivity and the coefficient of heat transfer of air gap and frame were calculated. The stator thermal field solving region of whole-slot and tooth is established. Based on the correlated thermal parameters calculated and analysis of electromagnetic field, the temperature distribution of the solving region is obtained, and the unindirectional coupler of electromagnetic field and temperature field was implemented. Finally, taking a small asynchronous motor for example, the stator... |
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