With finite the analysis uses yuan of method finite electromotor of yuan of law analysis asynchronous

35mm) silicon steel piece magnetize a curve 2, finite yuan of law is finite the fundamental of yuan of law is a kind of numerical value that with changing minute of principle and analyse assign interpolation to be a foundation computational method, the electromagnetism field problem that asks place slants namely melt into of issue of the cost side differential equation to it equivalent change minute of problem namely the extreme value problem of so-called float function. Get thereby high-ranking nonlinear equation group. Seek solution equation form finally, get the approximate solution that treats the electromagnetism field problem that beg namely. To use finite yuan of law solution equation (3) , must decide an appropriate functional above all. According to the extreme value principle of the function in calculus, can prove (the proof is omitted) functional. (5) with type (4) equal in value, namely afore-mentioned slanting the equivalence of the problem that decide solution of differential equation changes for the condition minute of problem. The condition changes minute of problem is as equivalent as its slant issue of the cost side differential equation is compared, want on attrib border problem handy much, and on such foundation ability undertakes analyse divides interpolation. According to the structure of electric machinery, the distributinging situation of the magnetic field when rotor position is different is different, the symmetry of magnetic field of structure of our make the most of, narrow its beg solution area. the affirmatory area that seek solution, analyse is divided into finite a triangular unit, analyse time-sharing, the commutative face of different medium must be the edge of triangular unit, density of cent of crucial part analyse is a few bigger, avoid to appear too pointed too blunt triangle yuan, in order to assure calculative precision. 2.

1 analyse divides interpolation to divide issue area analyse into a certain number of triangle unit, its acme is I, j, m, assume a function with type (6) comes approximate: A(x, the coefficient A in Y)=a+bx+cy (6) type, b, the independent equation that C can establish by 3 couplet will decide. Value of function of false fixed position is worth Ai for acme, aj, am, a value Ai of 3 acme, aj, am and its coordinate (X1, y1) , (X2, y2) , (X3, y3) era enters type (6) , the simultaneous equations that seek solution, get coefficient A, b, c, enter result era type (6) , have to arrive X, y and the elemental combination that go against coefficient matrix are new positional function, can write into 　 　 (the linear function that it is the position only in 7) type, and the area of Δ delegate triangle. Can obtain through the circular displacement of suffix, can prove type (7) it is a triangle of 3 acme inside insert function. 2.

2 finite yuan beg minimum to be worth functional type (5) in nonlinear the disperse below the circumstance, the same method that basically uses according to linear problem place undertakes. Assume the disperse of D of the region that seek solution of the problem becomes the limited unit that a group of each other do not overlap, emphasize a consideration an unit, inside individual unit, magnetic potential A can use formula (7) express, have the aid of is changed at this generation, w (A) become finite finite yuan of variable common function, what need thereby seek dinky value course simple is (the E0 in 8) type -- the total unit that analyse of the area that seek solution divides counts 　 　 L0 -- the total node that analyse of the area that seek solution divides is counted namely 　 of 　 of 　 of 　 of 　 of 　 of the  in type, criterion equation (8) turn short lineup into type: SA=J (10) the A in type -- J of 　 of 　 of vector of value of node magnetic potential -- current density lists vector, s of each 　 that it is 　 -- unit coefficient matrix, include following reluctivity the function that υ is A value, and still related to magnetic field. As a result of the saturation of iron magnetism material, reason equation (8) group of dispute linear equation, to the unit in air medium, the reluctivity of magnetization curve computation that presses its material and place frequency to fall. For applicable computer computation, undertake section interpolation, the magnetization curve of actual measurement, if pursue 1 show. The function Hi(i=1 that begins to take Bi of on the curve 25 node and correspondence from curvilinear turning, 2, ... , 25) , form Lagrange multinomial by B and H. Get thereby 2.

The 3 Newtonian iterative method that seek form of equation of Jie Fei linear set the accurate solution that A seeks for place, a(k) states one forbids truly but it is the estimation cost that approximates A appropriately however. A(k)=A- Δ A(k) (11) spreads out each heft of W(A) gradient A(k) around multivariate Taylor is progressional (12) if skip Taylor exceeds binomial in progression each an equation (12) offerred computational A(k) to be opposite the type of methodological Δ A=-P-1V (13) of the deviation of A, p nods the Jacobi matrix of Newtonian iteration, its element V is W(A) the gradient that is in in A(k) assumes by some group of initial value of magnetic potential A(k) A(0) comes out to construct now iteration method, use formula (13) computation this initial value is right the deviation of A, the magnetic potential that increases the deviation that this calculates original estimation next goes up, in order to make better estimation value, a(k+1)=A(k)+ Δ A, and repeat this process, 　 of such iteration format A(k+1)=A(k)-[P(k)]-1V(k) produced convergence to be listed at the Newtonian iteration foreword of A. 3, method of analyse of specific computation devoir is right model Y112M, rated power 4kW 4 extremely three-phase asynchronous electromotor, with its geometrical parameter is calculated on 486PC microcomputer. If its computation flow pursues 2, get this electromotor to distributing in the magnetic field when starting, if pursue 3 show and the magnetic field when empty running distributings, if pursue 4 show. Graph 2 computation flow chart pursues the magnetic field when electromotor of 3 three-phase asynchronous starts distributings graph the magnetic field when empty running of electromotor of 4 three-phase asynchronous distributings 4, as a result analysis and test and verify start empty running of moving a slight-pause mark used to set off items in a series from electromotor two kinds of operating mode part distributinging graph of earning magnetic field, apparently different. In starting instant, frequency of rotor electric current is equal to frequency of stator power source. Effect of rotor collect skin is distinct, enter the magnetic flux of rotor through air gap, cannot reach rotor yoke ministry, can cross in groovy surface ministry only. And electromotor is when empty running, slippery difference is very little, frequency of rotor electric current is very low, crowded spread effect very small. Because of magnetic flux of this air gap by alveolar cross enter rotor yoke ministry, distributing even. Confirm electromotor runs a state actually. We still were calculated this electromotor starting torsion and rotate speed character, input electric current and rotate speed character, computational value and into laboratory of guild regulations plasticity characteristic curve is accorded with, if pursue 5 show. Can see, with finite yuan of law analysis computation is accurate and reliable. Graph 5 characteristic curves 1, rotate speed of 1 ′ torsion is characteristic; 2, 2 ′ input character of voltaic rotate speed; -- computation is worth - - - measured value CNC Milling