Research On Adjustable-speed Permanent Magnet Coupler Of Axial Flux

The permanent magnet drive technology is consisted of mechanical engineer,materials science, electromagnetism, control and so on. A new product ofadjustable-speed permanent coupler(PMC) appears based on this technology, whichhas characteristics of transfering torque without contacting, damping, overloadprotection, allowing the error of centralization. And it’s widely applied for industrialfield, such as oil/petrifaction, coal mine, metallurgy. PMC is the study object of thispaper, the content is concluded of driving the electromagnetic torque expression,electromagnetic and adjustable speed device design of a novel PMC of bilateralstructure, temperature field analysis, speed regulation based on fans load andparameter optimization of high power, which are theoretical simulation analysis indetail and experimental verification.Firstly, based on PMC of the unilateral structure, the equivalent magneticcircuit and magnetic circuit are built, the electromagnetic torque expression of PMCcan be droved by using the way of ohm law and ampere force formula. And then, thecurve of torque, air length and slip is given. What’s more, taking advantage of finiteanalysis, a unilateral prototype with small torque is designed and manufactured. Theexperiment result is compared with simulation one and analytic formula one, and thedisadvantages of this kind PMC are proposed at last.Secondly, based on researching the unilateral PMC, it has the disadvantages ofhigh leakage flux and obvious skin effect, which lead to its low torque density. Thepaper proposes a novel bilateral structure PMC with magnetic circuit in series andaxial magnetic flux. The magnetic leakage factor and current density are comparedbetween the unilateral and the bilateral. It draws the conclusion that the bilateral onehas higher torque than the unilateral one. Meanwhile, the eddy current loss of thebilateral one is also higher. So the temperature field is analyzed based on thebilateral one at rated load and maximum load, whether permanent magnet materialwould appear the phenomenon of demagnetization.Thirdly, the adjustable speed device is designed for this kind bilateral PMC, sothat it could make squirrel cage induction motor start under load. And then theprototype of bilateral structure has been manufactured and tested. The result istested about the relationship between slip and torque at different air length forproving that the way is correct compared with theoretical value. At last, thesimulation system of fans load with PMC is built, in order to prove the point thatpermanent magnetic coupler has energy-saving effect. Finally, based on the researching of PMC with the bilateral of small torque, thehigher torque prototype used on155kW induction motor that is1000Nm need to beoptimally designed. The structure parameters effected electromagnetic torque areanalyzed, concluding copper, magnet and air length. At last, taking advantage ofmaterial utilization and torque requirements as the goal, the structure parameter withhigher torque density could be designed.