Modeling And Control Of Transmission Systems With Magnetic Gears

Magnetic gear is a new kind of transmission which realize the motionand torque transmission from the driving wheel to the driven wheelthrough the interaction between permanent magnet arrays. Compared withthe traditional mechanical gear, the magnetic gear doesn’t need directtouching between driving wheel to driven wheel, and it also eliminates theneed for complex teeth existing in the traditional mechanical gear. Thisfeature brings some advantages such as low processing costs, lubricationfree, low acoustic noise, easy maintenance, inherent overloadprotection.Magnetic gears have the potential of application in the newenergy industry, chemical factories, military equipment and otherfields.Until now, there have been some application examples in ship drive,electric vehicles, wind power, servo drives and other fields.This paper mainly discusses the modeling and control method ofmagnetic gears. A coaxial-type magnetic gear with a ring for modulatingthe magnetic field, called magnetic modulation magnetic gear（MG），isdiscussed in detail.1. Based on the theories of electromagnetic and motor, the basicstructures and principles of the magnetic modulation MG are discussed.The discussion includes some magnetic field waveforms and harmonic components obtained by finite element analysis (FEA). A devicecombining a motor and a magnetic modulation MG is also introduced.2. The nonlinear fitting method is used for modeling the torque modelof magnetic modulation MG in which the data are from FEA andexperimental results. For applying the model in control system design,some simplification methods of the nonlinear model are proposed. Thestiffness characteristic of MGs are analyzed.3. The PI method and observer pole placement method is applied todesign the controller of the servo transmission system with magneticmodulation MGs. The simplified models of the magnetic gears areincluded in the overall system model. In order to deal with the saturationproblem in the servo control system, some anti-saturation control wereproposed. The simulations results shows the improvement of the dynamicperformances after implementing the anti-saturation techniques.4. The system model of an electric bicycle driven by an electric hubwith a motor and a MG is established. Some complex factors includinghub electro-mechanical characteristics, friction characteristics and loadvariation are considered in it. In MATLAB/SIMULINK software, thedynamic system of the electric bicycle is simulated.5. Some relevant experimental studies are carried out. A transmissionefficiency platform, an electric bicycles experimental device and a servocontrol experiment platform are completed or partially establishedrespectively.