On The Electromagnetic Structure Of Spindle Permanent Magnet Synchronous Machine And Its Flux-Weakening For Wider Speed Range

Based on the requirements of the spindle drive of numerical controlled machine tools and the current situation of the permanent magnet (PM) synchronous motors (PMSM), a novel spindle drive using PMSM is proposed. Studies in-depth on both the motor electromagnetic structure and control method are carried out around the main issue, how to find a rotor structure for realizing the flux-weakening operation of the PMSM with satisfactory speed range.There are nine chapters and they are classified into six parts as follows.The first part, including the contexts of Chapters 1,3,4 and 5, mainly studies the natures and methods of the flux-weakening operation of PMSM and the relationships between the flux-weakening performance and the machine parameters. Chapter 1 presents the flux-weakening problem in details. Chapter 3 investigates the relationships between the variable-speed performance and the parameters of PMSM so as to meet the ideal flux-weakening condition E0=XdIN, and the optimal flux-weakening operation methods are described. Chapter 4 studies the flux-weakening operation of practical PMSM (E0>XdIN), in which the expression for the electromagnetic loading under ideal flux-weakening condition is derived and the relationship between the flux-weakening performances and the salient effect is surveyed, with a graphic method to show the flux-weakening control scheme given. Chapter 5 studies the relationship between the control behavior of PMSM and the salient effect.The second part (chapter 6) explores the PMSM electromagnetic structures suitable for flux-weakening operation. Requirements on the main dimensions and electromagnetic loading of PMSM for flux-weakening operation are discussed. The flux-weakening performance an protection of PM against demagnetization are compared for various kinds of PM rotors of general types and the composite ones. The d- and q-axis inductances ratios are compared for different type of structures of reluctance rotors.The third part (Chapter 7) presents some vital design techniques for the flux-weakening type of PMSM with composite PM rotor, among which are the uniform airgap machine with sinusoidal PM the inductance calculation for large uniform airgap machine, the effective armature length of the PM part of the composite PM rotor, the d- and q-axis saturated inductance calculation by FEM under any armature current and, the calculation of slot leakage inductance of machine with sinusoidal and mixed-phase windings and with more slots of different sizes, the electromagnetic design of composite PM rotor machine and the determination of the length of the two parts, PM and reluctance one of the rotor.The fourth part (Chapter 8) contributes to the development of mathematical model taking the d- and q-axis cross-effects due to saturation into consideration and to the model parameter identification for the PMSM with composite PM rotor.Part five (Chapter 9) describes experimental investigation results of the flux-weakening operation.Part six (Chapter 2) describes in detail the techniques developed during the field calculation by FEM and the automatic mesh generation. It is a fast Delaunay triangulation technique for random complex area and the time consumed is linearly dependent on the required number of elements and is independent on the complexity of the mesh areas.