Design Of A Linear Vernier Permanent Magnet Machine With High Thrust Force

Numerically-controlled machine tools(NC machine tools)have been widely used in various industrial applications such as aerospace,instrumentations and precise processing industry,whose developments,to some extent,depend on the progress of NC machine tools especially high-performance ones.For NC machine tools,the higher detent precision is the key requirement and tendency of its development,which drives the servo system to adopt the more direct,simpler and faster-response linear machine instead of the complex transmission structure consisting of rotational motor,ball bearings and lead screw.At the same time,with the upgrading of manufacture industry,servo systems in NC machine tools are required to exhibit higher thrust force(torque)density and lower thrust force ripple,which can eventually reflect the requirements for servo electrical machines in the systems.In large power and thrust(torque)applications,the combination machine of high-speed motors and mechanical speed reduction installations suffers from efficiency reduction and noise increase,etc.The vernier permanent-magnet machine,which belongs to an novel machine topology that works based on magnetic field modulation principle,has the inherent characteristic of higher thrust force density while lower thrust force ripple.Hence,linear vernier machine is quite appropriate to be used as the servo motor in NC machine tools and has a broad application prospect in manufacturing industry.In this thesis,a linear vernier permanent-magnet machine with high thrust force density and low thrust force ripple is designed considering working principle,influential parameters and requirements of performances.Firstly,the history of the linear machine is briefly introduced,and the development and research status quo of vernier permanent-magnet machine is reviewed.The linear vernier permanent-magnet machine is a combination of linear structure and vernier permanent-magnet machine working based on magnetic-field-modulation principle.The development and research hotspots of the linear vernier permanent-magnet machine are reviewed.Then,some key issues of design of linear vernier permanent-magnet machine are discussed including combination of poles and slots number,the improvement of thrust force density,end effect and thrust force ripple and power factor.The discussions will be the guideline for the design of linear vernier permanent-magnet machine.Then,the structures and characters of the linear machine especially the linear vernier permanent-magnet machine are highlighted.And based on its working principle,five linear vernier permanent-magnet machines of different structures are designed and their performances are compared including thrust force density.The comparison finds that the linear vernier machine with the surface-mounted permanent magnets that has no split teeth(S-LVPMM)has the highest thrust force density and it is selected and further optimized to obtain a linear vernier machine with the Halbach-array permanent magnets and modular primary(H-LVPMM).And the electro-magnetic performances of the two machines including thrust force,thrust force ripple under both no-loading and loading conditions and power factor will be analyzed and compared.Finally,considering the initial constraints for the servo machine,the cooling system and bracing structure of the H-LVPMM are designed.And its integrated performances including electro-magnetic are properties,temperature and mechanical stress are analyzed and summarized.