Research Of Mathematical Model Of Salient-Pole Synchronous Motor Based On Magnetic Network Method

At present, the concentrative parameter method of electric and magnetic circuit is widely used for electric machine design in our country. Because of its lower calculation accuracy, it cannot meet the requirements of modern electric machine design. The Equivalent Magnetic Circuit Network (EMCN) Method is based on electromagnetic field analysis, and avoids many coarse formulas. Therefore, the calculation accuracy and reliability are higher than that of conventional method which includes many coarse assumptions and empirical formulas and also spend much less calculation time than FEM. EMCN can be used in analysis and calculation of steady-state condition and performance of electric machine to improve the design level of machine in our country . The Equivalent Magnetic Circuit Network (EMCN) Method is based on combination between conventional EMCM (Equivalent Magnetic Circuit Method) and FEM ( Finite element method ). The conventional Magnet circuit Method transfer the field in electrical machine into magnetic circuit to analyze and calculate the parameters and performance of electrical machine and the FEM splits the magnetic field into many elements according to the different flux distribution in the machine. While the EMCN model is set up by use of flux-tube method, in this method, the segment in which the relatively flux density is even considered to be an element, the magnetic permeance of each element can be caculated by use of traditional method. Finally the magnetic permeance network can be set up by connecting each of nodes of permeance, according to the analogic method as electric circuit, then the parameters and performance can be obtained. EMCN can transfer the area in machine into several elements, each node and mesh are fixed and irrelevant to the rotor rotation. Only the values of permeances are related to motor rotation, but all the relations of the permeances are fixed. So, only the permeance value should be calculated again when the dynamic performance is considered. There are few elements in EMCN, the mesh time can be reduced greatly and calculation time is much less than FEM time. EMCN considers the influence of the different flux distribution and leakage flux in different section of electric machine. The calculation accuracy is greater than conventional EMCM. EMCN method possess the advantages of conventional EMCM and FEM method. So the method has many advantages in calculating special field such as 3D field and highly saturated field, moreover, the calculation results meet the requirements of engineering. This paper analyzes and calculates the salient synchronous motor with 1100kW rated output power and 22 poles. The calculation results are compared with the results of 2D FEM and conventional EMCM. The comparison shows that the calculation results of this method is more accuracy than EMCM , and in some complicated conditions such as the number of the slot per pole and phase of the motor is not integer or the the shape of motor is irregular the calculation results of EMCN is also more accuracy than FEM. The results are also meet the requirements of engineering.