| Wind power isanimportant way to solve the problem of energy shortageand environmental pollution. The research about wind generator which is theimportant part of wind power system has important significance to thedevelopment ofwind power industry.C-rotorironless direct-driven permanent magnet wind generator（DDPMWG）without core not only inherite the conventional DDPMWG atlow speed, high efficiency, high reliability, and many other advantages, butalso can better overcome theshortcomings of conventional DDPMWG suchasthe cogging torque, vibration and noise pollution and so on. Besides it hasa lighter structural quality.Butas a new type of structure of generators, atpresent there is few research about it and it is not very comprehensiveas itstill has many deficiencies.This paper is maily for reviewing the meaning and background of windpower and the developmentstatus of direct drive windturbine,includingironlessgeneratorand the general classification ofthem;summaring the general design structure of C-rotor generator and thereasonable scope of performance parameters. It introduces the structure andcharacteristics of C-rotor ironlessDDPMWG in details.According to thestructure characteristics of C-rotor ironlessDDPMWG, RMxprt is adopted todesign a conventional outer rotor DDPMWGto provide the reference forsubsequent research. The generator model is designed by SolidWorks, and thesize ofPM in C-rotor ironless DDPMWGmounted conventional PMon the influence of air-gap flux density and harmonic distortion rate of no-loadvoltage are analyzed by the finite element analysis（FEA）software Maxwell2D.Given thatthe rotor quality of C-rotor ironless DDPMWG mountedconventional PM is too heavy, the paper put forward a method that by usingsegmentedmagnetic steelinstead of the conventional magnetic steel.Firstly,thedifferent reference angle of the first piece PM usingHalbach arraymagnetization formula in cylindrical coordinates which would cause that theadjacent losed magnetic circuit in common or not common PMcaused theinfluence of air-gap flux densityare analyzed;By analyzing magnetizationdirection characteristic of each pole consisted of3pieces of PMs, A newconcept of included angle isproposed whichis very suitable for rectangularPMof C-rotor ironless DDPMWG; the different magnetizing direction of thesegmented PM effected on air gap flux density and the three-phaseshort-circuit characteristics of the generator and the torque under rate powerare analyzed, Finally it compares the quality of the main materials betweenC-rotorironless DDPMWG mounted conventional PM and segmentedPM. |
