| Long-stator permanent magnet linear synchronous motors(PMLSM) have advantages of small mover mass, good reliability and modular stators design taking efficiency, controllability and safety life cycle into account. So they have broad prospects in high-speed and long-stroke applications of drive system. There are many types of combinated topologies, the subject of this paper is continuous-stator multi-segment PMLSM. Because its secondary and modular segment are finite, the multi-segment PMLSM with two aspects of disconnected longitudinal ends has different electromagnetic characteristics from conventional linear motor. This paper discusses the mechanism of two types of longitudinal end effects and explores equivalent methods of magnetic field and magnetic circuit analysis. Further, electromagnetic parameters and electromagnetic force fluctuation are analyzed. Finally operation characteristics are summarized and optimized measures are proposed, so accurate motor mathematical model canbe achieved and their application scopes canbe widened.First, electromagnetic programs of modular style, segment lengths and pole/slot combinations are analyzed with motion and drive mode. On this basis, considering large copper loss in long-stator PMLSM, the studies of electrical and magnetic load match for maximum motor constants are carried out, and the calculation methods for different pole/slot combination are presented. These studies will provide a reference for determination of main design size. And then motor constants testing validate the analysis results, and they are sensitive parameters to reflect motor magnetic saturation. Subsequently, the problems of special shaped PM magnetization characteristics, half-opened domain and regional magnetic field calculaton are solved. The dynamic behaviors of magnetic field in pass-through section are described by variation of airgap magnetic energy storage. Investigation of basic electromagnetic calculation will lay theoretical foundation for two types of longitudinal end effects analysis.In this paper the longitudinal end effects of PM and modular stators are discussed respectively. Firstly, modeling of PM longitudinal end effects is established, and then the corrected factors of magnetic field calculation are analyzed by boundary condition method. The analytical results of magnetic field indicate that the PM end effects can give rise to two mechanisms, uneven airgap magnetic field and partial saturation. Choosing a reasonable size of edge poles and extended mover yoke can suppress these effects. Further, simplified unloaded equivalent magnetic circuit model is studied. The calculated methods of flux leakage coefficients are revised and their sensitivity analyses are accomplished. The dynamic flux analysis model is proposed and the typical kZth harmonics of PM flux are analyzed. Finally the analysis results are verified based on back EMF and flux calculation.As for longitudinal end effects induced by modular stator, influence of unexciting stator iron core on edge magnetic field are focused on, and inductance characteristics of one modular stator are examined with different boundary condition. The results show that the path of leakage magnetic field at the ends in slotted linear motor are restricted, and end magnetic fields are less affected by the length of extra iron core; Self-inductances of end coils in the first and end segments for concentrated-windings motor are less than that in middle coils. Subsequently the testing of asymmetrical phase characteristics are carried out, and the non-associated and associated factors of asymmetrical current state are obtained. Further, inductances in pass-through section are discussed by analytical and finite element method. The relationship between combinational size and inductance parameters are explored. The calculated results indicate that accurate parameterized analysis of phase inductance can be achieved by magnetic field energy perturbation method and simplified "compensated electromagnetic energy storage of end coils" methods. Researches on equivalent magnetic circuit model and associated parameters are helpful for exact expression of electromagnetic relationship. They are also important steps and foundation for static and dynamic characteristics analysis. At the same time the establishment of design criteria is instructive to design process.Based on regional and end effects magnetic field analysis, the calculation and testing method of key parameters are studied. Firstly d, q-axis and its coupling inductance characteristics depending on current and mover position are obtained by harmonic coefficients of self-and mutual inductance waveforms. The coupling inductance testing based on sine-wave source and the operations of differentiation on recorded data are proposed. It is noted that coupling inductance of the first, middle and end segments are dfferent for concentrated-windings linear motor. The peak to peak value of coupling inductance waveform in first segment is maximum, while that in the middle segment is minimum. And then the speed and load characteristics of regional iron losses are evaluated by Bertotti model. Further iron losses involved dynamic behavior and the length ratio are analyzed. To extend the applications of motor model, the relationship between parameters and basic assembled size are established. On this basis, the dynamic simulation model of multi-segment PMLSM considering iron loss is built and analyzed.Two types of longitudinal end effects are important source of electromagnetic force fluctuation for multi-segment PMLSM. Firstly the uniform analytical model is proposed to analyze the frequency characteristics for PM linear synchronous motor, and then thrust ripple characteristics are analyzed by EMF and current method. Furthermore, the corresponding modulation methods of edge magnetic field are proposed. The splitting edge magnets and unequal pole-arc coefficients method are effective to suppress the specific electromagnetic force fluctuation. The non-ideal electromagnetic conditions for multi-segment PM linear synchronous motor includes: the diverse of long-stroke mechanical air gap status and the errors of adjacent stator winding current in pass-through section. The detent force and thrust ripple characteristics are discussed with non-ideal electromagnetic conditions. The analysis results indicate that the amplitude of electromagnetic force fluctuation increases with non-ideal electromagnetic condition, and the fundamental frequency have changed to2p times obviously. The bias of current amplitude has impacts on mean thrust and thrust fluctuation, while phase difference only affects fluctuation. These analyzes will lay theoretical and technical foundation for development of the novel and reliable linear motor system. |
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