Calculation of armature fields and reactances for the design of double disc alternators

Double disc machines with hybrid excitation use permanent magnets to provide the bulk of the excitation and an excitation coil for output voltage adjustment. Finite element modeling techniques are used to find the unsaturated synchronous reactances of the machines and to model all the fields on load. A magnetostatic approach is used, and it is shown that the method gives results which compare well with experimental data taken from a prototype machine