Machine efficiency optimization using ripple correlation control

It is well known that when DC and field-oriented-controlled induction machines are under-loaded they experience unnecessary losses because of excessive field excitation. Present methods to provide an adaptive flux reference involve extensive calculation based on machine models, or intentionally perturb the rotor flux to obtain gradient information. This paper presents a straightforward and convenient method of optimization based on ripple correlation control. Exact parameter knowledge is not needed and the method has small computational requirements.