Online optimal flux-weakening control of permanent-magnet brushless AC drives

An enhanced online optimal control strategy, which maximizes the flux-weake ning performance of a brushless ac motor, is described, and applied to moto rs having different rotor topologies: interior (radial or circumferential), inset, and surface-mounted magnet. It enables the maximum inherent power c apability of a brushless ac motor to be achieved independent of any variati on in its parameters,and facilitates maximum efficiency over the entire spe ed range. It also results in good transient dynamic performance, since it i s coupled with feedforward vector control based on optimal current profiles .