High-power density radial-flux permanent-magnet sinusoidal three-phase three-slot four-pole electrical generator

摘要

Compared with conventional electrical machines, permanent-magnet (PM) machines experience higher efficiency, higher power-to-weight ratio and simpler construction. In this paper, a new three-slot three-phase four-pole rare-earth radial-flux PM variable-speed electrical generator is proposed, designed using Finite Element Technique (FET) and is investigated. In this topology, the soft magnetic material of the rotor is placed at the pole faces of the rectangular high-energy magnets. An air-gap flux density distribution very close to sinusoidal is achieved by curving the faces of the rotor soft magnetic pieces. The steady-state characteristics at different rotational speeds and loading conditions are addressed and compared. Basically, slotted PM electrical machines suffer from cogging torque. The cogging torque of this generator is predicted and compared to the rated value of the machine. The windings, located at flat slots, have short ends which therefore adds further improvements on the efficiency, power-to-weight ratio, operational performance and cost of active material. The obtained output operational performance characteristics of this generator along with the acceptable peak value of the cogging torque demonstrate the success of the topology and the effectiveness of the design methodology.