Use of equivalent fields in electrical-machine studies

The terminal behaviour of electrical machines is usually described by means of equivalent circuits. To design machines to meet a specification, the manufacturer needs to be able to relate the internal magnetic field to the circuit parameters. It is not generally possible to obtain a complete solution to the field problems, nor is this necessary. A method is described in which the field is subdivided into regions that are then matched to each other. The individual regions can be identified with circuit parameters and equivalent circuits can be constructed in which the different branches have a clear physical significance in terms of the magnetic field. The method can also be used in the calculation of power and torque.