Nonstationary Magnetic Fielddistribution in Yoke of DC Machines and its Particularities

ABSTRACT

Eddy currents in the quadrature axis of O.C. machines, which arise in nonstationary conditions, affect the performance of the machine considerably. The nonlminated yoke of O.C. machine carry eddy currents, and the quadrature axis components of their M.M.F's are very important in analysing machine performance. For example the importance of these M.F.F. components in performance of the machine is evident from the fact that the normal commutation of machine may be severely disturbed due to their damping action on the magnetic field in the zone of commutation. But the yoke of D.C. machines due to its position in the magnetic circuit does not distribute its flux symmetrically in its radial section. This phenomenon, which is not considered in the publications, may perceptibly change the mathematical model, describing the effects of quadrature axis M.M.F. on the machine performance. But its mathematical consideration should be rational and easy in programming for computer analysis. In the present article the above mentioned task is performed.