Outer-rotor type permanent magnet reluctance generator with high power and low toque ripple

摘要

This paper presents an outer-rotor type permanent magnet reluctance generator (PMRG) for a small-scale windturbine and micro-hydroelectric power generation. First, this paper describes a PMRG using ferrite magnets. Residual magnetic flux density of the ferrite magnet is about three times lower than the rare-earth magnet, but the cost is about 10 times lower. It is demonstrated that the proposed PMRG with ferrite magnets has almost the same output power as that using rare-earth magnets by employing an outer-rotor structure. Next, a method for reducing torque ripple of the PMRG by stacking two rotors is proposed. One rotor is shifted by 180º in electrical angle from the other rotor. In addition, the rotor pole-tips are chamfered so that the toque waveform consists of only odd harmonics. In such a structure, the torque ripple can be almost cancelled. A trial two-stacked outer-rotor PMRG demonstrates that the maximum output power is 777 W, the efficiency at the point is 84.5%, and torque ripple is very low.