General theory of induction machines with unlaminated secondary and constant-current excitation

A general theory of induction machines with unlaminated secondary and constant-current excitation is presented, based on a previous treatment of such machines with constant-voltage supply. The results are presented in the form of generalised curves of nondimensional coefficients, which, in conjunction with simple scaling factors, enable the torque/speed characteristic of a given machine to be evaluated. A computational method is described for taking into account saturation in the magnetic circuit and the validity of the treatment is demonstrated by correlation with tests up to high levels of saturation. The results are particularly relevant to modern eddy-current machines such as dynamometers, brakes and couplings.