Optimum design and performance calculations of highly magnetically saturated d.c. machines for large-scale production

The paper describes a computer program to predict the performance of a highly magnetically saturated, uncompensated, direct-current machine. The program is used in conjunction with other programs to design cost-optimised machines. A review of analysis and synthesis techniques used in the optimisation process is included. The performance calculations determine the main- and leakage-flux distribution in the machine under all load conditions, with full allowance for saturation. It is applicable to machines with few slots per pole, as allowance is made for inactive conductors and the stepped armature-m.m.f. pattern. Tapered teeth are represented effectively by equivalent rectangular teeth, the dimensions of which depend on the flux density. A practical method of representing the gradient of flux density in a changing section in the region of the pole and yoke is presented. A comparison of predicted and test data of machines, with different numbers of slots and frame sizes, are included to support the theory.