Electromagnetic Field Study And Parameter Calculation Of Slit Solid Rotor Asynchronous Motor

Solid rotor asynchronous motor is with simple manufacture,low cost and high reliability.It is applicable to the field of high speed drive.However,its power factor and efficiency are low,which can be improved by slotting in axial direction on the surface of the solid rotor.After slotting in axial direction on the surface of the solid rotor,the solid rotor is with better electrical and electromagnetic property.Calculation of three-dimensional non-linear vortex field is the fundamental method to analyze the performance of slotted solid rotor asynchronous motor.In the previous scientific research and exploration,the three-dimensional field is usually simplified into two-dimensional field to simplify the workload of calculation,so that the factors,such as the current at the end of the rotor,etc.are ignored,therefore,the calculation results are with relatively large deviation.The present article uses three-dimensional finite element method to analyze the magnetic field of this motor.The factors such as core saturation and end effect can be fully considered,which provides a basis for the design optimization of the motor.After slotting in axial direction on the surface of the solid rotor,in rotor teeth,there is not only the magnetic field distributing along the tangent direction,but also the magnetic field distributing along the radial direction.Therefore,it is quite difficult to accurately calculate the rotor parameters of this motor.In previous studies,the homogeneous medium whose axial slotting area is equivalent to anisotropy is used for replacement for calculation,so that the results are with relatively large deviation for the difference of the magnetic fields distributing in rotor teeth and yoke.The present article starts from the actual distribution of the internal magnetic field of slotted solid rotor,it uses unit magnetic impedance method and analytical method to calculate the rotor impedance,current,electric potential and loss of slotted solid rotor asynchronous motor,respectively.The parameters of the slotting with different axial directions on the surface of solid rotor and asynchronous motor solid rotor surface will affect the eddy current distribution in the solid rotor so that the operating performance of solid rotor asynchronous motor will be affected.To determine the best slotting parameters of slotted solid rotor,three-dimensional finite element method is used to analyze the different depth,width and quantity to obtain the effect law of different parameters of the slots on the surface of solid rotor on the power factor and output torque of slotted solid rotor asynchronous motor.The present article analyzes the magnetic field distribution of solid rotor asynchronous motor with no load and locked-rotor and calculates the values of counter emf and torque,etc.though three-dimensional finite element method.By the comprising to the testing results of the sample machine,and by using three-dimensional finite element method to analyze solid rotor asynchronous motor,more accurate calculation results can be obtained.