Design And Parameter Studies Of Soft-start Permanent Magnet Eddy-current Coupling

With the deepening of the permanent-magnet materials, permanent-magnet eddy-current coupling has been developed rapidly. As a kind of advanced transmission device, it has many advantages compared with other kinds of couplings, such as soft-start, shock load tolerance, speed governing, variable torque, misalignment tolerance and so on. But several parameters are analyzed in the research in the recent years, lack of comprehensive study. The forms of conductor plate are few, and the assembly deviations are not mentioned. The thesis mainly researches permanent magnet eddy-current coupling, analyzes multiple parameters comprehensively, and studies the assembly deviations and heat dissipation.This thesis firstly analyzes the domestic and foreign literatures, introduces the operating principle, types and basic structure of the permanent-magnet eddy-current coupling, and illustrates the working process of the PM eddy-current coupling in detail with the analysis of the magnetic circuit and the forming process of the torque. And this thesis designs the structures of the 7.5 kW soft-start of the PM eddy-current coupling, mainly including the design of double linkage mechanism, the selection of torque transmission path and the integral structure.This thesis secondly researches the parameters of permanent-magnet and the conductive disk in detail with ANSOFT software. The parameters of permanent-magnet include PM material, form, duty cycle, quantity, thickness and diameter. The conclusions are that the material is the NdFeB 35, the form of the PM structure is sectors, duty cycle is between 75~80% considering various factors, the quantity is 14, the thickness ranges from 16 mm to 18 mm, the diameter is determined by the torque and other structure space. The parameters of conductive disk are mainly four kinds of different structure types, such as ring conductor plate, bar structure, slotted conductor plate, and slotted plate filled magnetizer. Analyzing the four kinds of structure and comparing respective advantages, the ring conductor plate is selected as the conductor structure. By simulation calculations of the conductor disk thickness and diameter, the conclusions are that the thickness of conductor disk ranges from 4 to 8 mm, the diameter is determined according to the requirements of the assembly deviation and the size of the transmission shaft.Finally the assembly deviations of the PM eddy-current coupling are analyzed, including the axial gaps, radial distances and transverse angles. It can be concluded that the axial gaps can be removed between 2~5mm with no enormous effect on the torque, radial distance deviations have no effect and transverse angles can increase the torque but causes overturning moment in the coupling. The conclusion is that the PM eddy-current coupling can effectively tolerate the assembly deviations. The thermodynamics of coupling is simulated by uniting ANSOFT and ANSYS, concluding the structure of the 7.5 kW coupling itself can meet the cooling requirement. For higher-power couplings, additional cooling devices are needed. This thesis introduces a variety of air cooling devices and water cooling devices.This thesis gets a reliable soft-start PM eddy-current coupling, and its research methods and conclusions can provide foundations for the practical application.