The Key Technique Research Of A MW Level High-speed Permanent Magnet Wind Generator Which Based On Plate Structure

With the rapid development of economic and improved the living standardsof people, the energy demand of the world is growing. The energy consumptionwill certainly lead to environmental pollution, great consumption of energy willrestrict the development of economy and the progress of human. Wind powerrelay on clean, abundant, renewable and other advantages attract more and moreattentions, and the development level of wind power generator is directly relatedto the utilization of wind energy, now direct-drive permanent magnet windgenerators and double-fed induction generator become the main market models.Riding through low voltage capability of permanent magnetic isstrong, but also it has high reliability. But it costs high because of the price ofthe permanent magnet； the cost of double-fed induction generator is low,because its failure rate of high speed gear box, and it has no collector ring andbrush, so it reduce the reliability of the system； In addition, the aircraft lowvoltage crossing ability is low, with great risk of electricity from the grid. Thispaper presents a high-speed permanent magnet wind generator, the models andthe direct-drive permanent magnet wind generator has the same electricalcharacteristics, and low cost. It has no collector ring and brush compared withthe double-fed induction generator, so it has high system reliability, and goodequipment replacement. Therefore, directly replacing asynchronous doubly-fedby the same fan center high permanent magnet wind generator, without the needfor replacement of supporting facilities, which greatly reduce the cost and savetime to replace the generator, and the type of low voltage of the motor crossingability is strong, there is a lower risk of interconnection； Because of thepermanent magnet fan asynchronous doubly-fed fan power density is relativelyhigh, so the volume of the former is1.5times of the latter while they have thesame capacity. The2.1MW motor than the1.5MW asynchronous doublyfed wind generator weight300Kg.Therefore, at present some wind powergenerating factory will regard it as the important developing object in the future. In order to solve the asynchronous doubly-fed fan low voltage across theproblem of low capacity, we need to design a high speed permanent magnetwind generator with mechanical displacement, in this case by an ElectricalMachinery Factory independent research and development projects as a platform,designing a power of2100kW, high-speed permanent magnet wind turbinerotating speed is1800RPM.According to an ABB product, we design and research a high speedpermanent magnet wind turbine generator. The first design of the rotorstructure, which adopts the lamination structure, pole shoe structure can greatlyreduce the eddy current loss, alleviate the burden relative to the motor cooling;magnetic bridge design for the vertical structure, and the magnetic bridge of theconventional motor for horizontal structure, vertical wind so generated whenthe motor works, into the stator cooling hole, improve the heat dissipationcapability of a motor, and the magnetic bridge is arranged at the lateral side inround chamfer angle, which can reduce the wind friction loss; magnet motor byway of blocks, in order to ensure the mechanical strength of the rotor, the needto increase several reinforcing ribs； On the rotor magnetic circuit structureanalysis of several forms, permanent magnet wind turbine generator complexwork environment, permanent magnetic working point high based on thecharacteristics of magnetic circuit design, determine the structure of rotor. Andthen design the stator armature windings, based on the analysis of thefundamental magnetic flux harmonic minimization, maximization, determinethe armature windings with double short distributed windings, calculate thefundamental distribution factor； Finally carries on the design of the machinestructure size, first give motor general design principles, based on thedetermination of main dimensions and air gap motor design length, according tothe design principles for determining the size of permanent magnet.Because the permanent magnet synchronous motor itself possesscharacteristic, compared with asynchronous doubly-fed motor, its existing whenan unpowered cogging torque, the cogging torque can cause the torqueripple, thus affecting the vibration and noise of motor, the motor air gap ofthe research8mm, and the motor air gap in general is3-5mm, so the design cangreatly reduce because of tooth, groove gap between different motor causedby vibration, noise and harmonic interference； a permanent magnet is divided into four block and non-uniform air-gap to cut down the cogging torque ofthe motor, at the same time,using permanent magnet block method can reducedegree of difficulty of installing permanent magnets, But the permanentmagnet block will affect the mechanical characteristics of rotor structure,required in the fourth chapter of the rotor in the super rotation analysis ofcontact stress, ensure the safety of the motor； through the finite elementsimulation analysis,determine the cogging torque are reduced by using abovetwo ways； Using a combination of electromagnetic and magnetic methods tocalculate the key parameters of the motor, including arc coefficient, magneticflux leakage coefficient of the motor, calculating the working point ofpermanent magnet, analyzing of no-load voltage waveform distortion rate；Making an research on permanent magnets for anti-demagnetization, using thesteady-state current to check demagnetization of permanent magnets, usingAnsoft software for three-phase armature winding short circuitsimulation to determine the safety of permanent magnets in the extremesituation； At the same time, making a comparative simulation analysis betweenthis topic designs motor and the conventional structure, contrasting the eddycurrent loss situation, we can get plate structure of the motor rotor eddy currentloss is decreased obviously.Analyzing the rotor structure by the finite element simulation software(ANSYS), determining the stress, strain of rotor’s stiffeners at2400rpm,determine whether the stress within in the range of material’s yield strength.This needs to carry on the comparative analysis of different circumstances. First,maintain a single block, the rotor magnet size premise of strengthening rib totalsize constant, in different magnetic steel blocks (reinforcement of differentnumber), namely the single stiffener size on the contact stress analysis, finallydraws the five stiffeners dimensions were2mm,3mm,2mm,3mm and2mmmeet mechanical strength, better size.Testing the developed prototype before delivery, verifying it conform to therequirements of the industry as well as the design purpose.