Design And Research On Outer Rotor Permanent Magnet Synchronous Generator For Base Station

With the development of communication industry in our country and the increase in the number of communication base stations and power equipment,the emergency power supply generator of base station has been widely used.Due to the limitation of the space of the base station,the generator has the characteristics of small volume,high efficiency and easy maintenance.Under this background,the outer rotor type permanent magnet generator with fractional-slot concentrated winding is gradually applied in the communication base station.Outer rotor type permanent magnet generator with fractional-slot concentrated winding has characteristics of high power density,high efficiency,light weight,convenient maintenance.Due to the fact that the magnetic motive force harmonics generated by the fractional slot concentrated winding are higher than that of the integral slot,the eddy current loss of the permanent magnet can not be ignored;The communication equipment has a higher requirement on the inherent voltage regulation of the generator.In this paper,the two problems of the eddy current loss of permanent magnet and the inherent voltage regulation rate of the outer rotor type permanent magnet generator with fractional-slot concentrated winding are studied.Research on eddy current loss of permanent magnet: Firstly,the cause of eddy current loss of permanent magnets is analyzed from the change of air gap permeance,stator magnetic motive force space harmonics and stator current time harmonics.Secondly,the finite element method of eddy current loss of permanent magnets is studied.At last,the influence of slot/pole combination,air gap length,pole arc coefficient and slot openings on the eddy current loss are analyzed.Research on generator inherent voltage regulation rate: The equivalent magnetic circuit of quadrature and direct axes method is used to calculate the reactance parameters,and the influence of air gap and length of permanent magnet magnetization direction on the inherent voltage regulation of the generator is studied from the point of improving the saliency ratio.The magnetic material is added between permanent magnets in the rotor,which can obviously improve the saliency ratio.A 6.5kW outer rotor permanent magnet synchronous generator was designed.Three kinds of slot/pole combinations are analyzed from three aspects: the eddy current loss of permanent magnets,the amounts of effective material and the cogging torque,and choose one kind of slot/pole combination with magnetic material added between permanent magnets to reduce the inherent voltage regulation rate.The output voltage of the generator is simulated by an external circuit to verify the rationality of the design.