Study On Torque Calculation And Mechanical Properties For Squirrel Cage Asynchronous Magnetic Coupling

In order to realize non-contact connection and power transmission, the rolling magnetic field of asynchronous magnetic coupling is motivated by permanent magnet excitation. Then, the induction current to transmit torque is induced in the course of cutting magnetic field by the squirrel cage conducting bars. What’s more, aiming to decrease energy consumption of the prime motor, the stepless speed adjustment can be achieved by adjusting air gap contact area. In a word, the advantages of asynchronous magnetic coupling can be concluded, such as light load starting, inherent overload protection, high transmission efficiency, energy conservation and so on. It opens up a new avenue of studying magnetic transmission technology.A novel Squirrel Cage Asynchronous Magnetic Coupling (SCAMC) is proposed in this thesis. The two-dimensional field boundary conditions is obtained in magnetic scalar potential method and theory of electromagnetic induction here to establish the air gap flux density and induced current analysis model of SCAMC. Not only is the amplitude and period of the air-gap flux density waveform described intuitively, but also the change laws on the induction current among each squirrel cage conducting bar is revealed in detail. Especially for the law changing with space phase and electrical degree.Based on the armature reaction magnetic potential of SCAMC, the equivalent magnetic circuit method and the relationship of energy flow are adopted here to establish and calculate the analysis model of SCAMC’s electromagnetic torque. What’s more, based on the cogging torque model and finite element software, the permanent magnet and squirrel cage rotor structure sizes’impact on the amplitude and fluctuation of SCAMC’s electromagnetic torque is analyzed in detail. In order to optimize the magnetic circuit structure, a method of selecting the number ratio between permanent magnet pole pairs P and squirrel cage rotor slot Z is put forward.In order to establish the stable operation and optimum efficiency conditions, mechanical properties and efficiency characteristic of SCAMC are studied in detail. In order to lay the foundation for the SCAMC’s prototype design, the design and verification of SCAMC’s structure is finished as well.According to the principle of constant magnetic energy, a size conversion method of increasing the size of width and decreasing the size of magnetizing direction is put forward to optimize permanent magnet size. To verify the method, FEM is adopted here to compare the performance index about before-and-after the size conversion. A prototype of37kw SCAMC is designed and tested, which proves that the theory and technology in this thesis is efficient and reliable.