Performance evaluation of a dc motor fed from an asymmetrical single-phase bridge

Lack of simple methods for predicting some of the losses in a machine in service has limited the theoretical work on additional losses in DC motors with armature current ripple to the prediction of additional copper losses. The additional core losses of a machine fed from the asymmetrical single-phase bridge are predicted from equivalent circuits which contain elements for the core. A method is developed for predicting the additional ‘skin effect’ losses in armature conductors. It is proposed that, by the use of generalised charts developed, the derating of a ‘standard’ bridge-fed DC motor at a specified operating condition can be estimated from look-up tables of additional losses measured on a standard machine.