Abstract
Shaft is an important part of rotor, whose electromagnetic characteristics have an impact on the performance of the motor, especially when large diameter shaft and thin rotor yoke are adopted in the two-pole induction motor. Taking a 3 kW two-pole three-phase induction motor as an example, the two-dimensional electromagnetic field model of the motor is established by using finite element method. Firstly, by analyzing the difference of current, power factor, loss and magnetic field distribution of the motor with different shafts that are made from ferromagnetic and non-ferromagnetic materials. It is determined that the different magnetic saturation degree of rotor yoke is the key factor affecting the performance of motor when different shaft materials are used. Secondly, it is verified that the traditional analytic design method has the inaccurate design problem of the rotor yoke height due to neglecting the specific electromagnetic characteristics of shaft material. Finally, by comparing the differences of motor performance when several common magnetic shaft materials are used in motor shafts, the advantages of various shaft materials in improving motor performance are found. The presented results give guidelines to selecting shaft materials to improve motor performance.
Analytic design method for optimal imaging: coupling three ray sets using two free-form lens profiles
