Influence of Magnetic Losses on Maximum Power Limits of Synchronous Permanent Magnet Drives in Flux-weakening Mode

The aim of this paper is to present the structure of a new synchronous machine with stator ferrite permanent magnets and a salient passive rotor (a robust and low-cost technology) which, when supplied with current by a threephase bridge converter, produces continuous torque. This feature serves to place our machine on a par with the best synchronous machines available (e.g. high-energy rotor magnets with flux concentration). Furthermore, the electrical characteristics of this machine make it possible to apply the well-known flux weakening technique, which enhances the performance of the entire energy-conversion system. In theory, an operating area at constant power with unlimited speed can be obtained merely by taking into account the ohmic tension drops in the coils. Experimental results demonstrate that taking both magnetic losses and windage losses into account is necessary in order to identify the maximum mechanical output power characteristics.