Computing the field in permanent-magnet axial-field motors

A closed-form expression is presented for computing the axial field in the coil region of permanent-magnet axial-field motors. This expression, which is based on a two-dimensional approximation of the motor geometry, takes into account the finite slope of the demagnetization curve of the permanent-magnet. It can be used to perform parametric studies of field strength and to test new numerical methods. It is tested using finite element analysis (FEA).<>