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For permanent magnet linear synchronous motor (PMLSM), the end effect not only changes the distribution of the end magnetic field, but also causes the pulsating magnetic field in the air gap between the primary and the secondary components. In this paper, the existence of the pulsating magnetic field is proved and the characteristics of the pulsating magnetic field are analyzed through the finite element analysis. On the base of that, the influence of the pulsating magnetic field on the detent force is studied, of which the result shows that the pulsating magnetic field generates the pulsating magnetic force, which is a part of the detent force. The amplitude of the pulsating magnetic force is closely related to the length of the primary component. By adjusting the length of the primary component, the pulsating magnetic field can be effectively suppressed. Moreover, the results of simulation and theoretical analysis prove that with the increase of primary component length, the influence of pulsating magnetic field is becoming weaker and weaker. Finally, a prototype is made to test the detent force characteristics, which verifies the research theory in this article. [ABSTRACT FROM AUTHOR]

A segmental permanent magnet linear synchronous motor (S-PMLSM) with noninteger pole number, which has low detent force and high thrust, is presented in this article. For the S-PMLSM, the noninteger pole structure makes up for the defect that the conventional integer pole structure cannot suppress the third and its times harmonics in the detent force, thereby further reducing the thrust ripple rate of the motor. Special winding arrangement is adopted for noninteger pole structure, of which the winding factor is relatively high. Another advantage of the noninteger pole structure is the decoupling between the detent force and the cogging force. When designing cogging parameters and structures, it is not limited by the requirement of the detent force, which enlarges the range of cogging parameters and finally helps to improve the motor thrust. In this article, 18-slot 24-pole and 18-slot 19.2-pole S-PMLSMs, representing integer and noninteger pole structures, respectively, are selected as samples for comparative analysis. The results show that the later removes almost all detent force while giving higher thrust than the former. The simulation and experimental results validate the research theory. [ABSTRACT FROM AUTHOR]

A novel flux switching permanent magnet linear motor (FSPMLM), which has the advantages of high thrust density [the ratio of average thrust to permanent magnet (PM) volume] and low cost for long-stroke application, is proposed and investigated in this article. The topology of the novel FSPMLM with 12 slots is introduced and the basic operating principle is analyzed first. The optimal geometric parameters are selected by using the layered orthogonal optimization method. Then the electromagnetic performance of the motor is investigated by the analytical method based on the equivalent magnetic network model (MNM). Finally, a scheme of setting auxiliary teeth in the primary component is adopted to suppress the unbalance of the three phase flux linkages. [ABSTRACT FROM AUTHOR]

Modularization design has been widely used to reduce the detent force of permanent magnet linear synchronous motor (PMLSM). For modular PMLSM, ideally, unit motors are independent of each other and the detent force of the whole motor is the sum of that for unit motors; thus, the whole motor's detent force can be suppressed by adjusting the phase difference among the unit motors’ detent forces. But actually, there is coupling effect between adjacent unit motors, which has adverse effect on the detent force suppression. The coupling effect changes the magnetic field distribution, which is often neglected in current research. Hence, this paper carries out the research on magnetic field analysis and flux barrier design for modular PMLSM considering the coupling effect: the influence of the coupling effect on the air gap magnetic field is clarified through magnetic field analysis; the coupling force is isolated by finite element analysis, and then the effects of key parameters are discussed; the whole motor's detent force model considering the coupling effect is established, and an optimal design method of adjusting the flux barrier length is presented to suppress the detent force. Finally, a prototype is made to test the detent force characteristics with different flux barrier lengths, which verifies the research theory in this paper. The research results in this paper can provide guidance and reference for the design of modular PMLSMs. [ABSTRACT FROM AUTHOR]

Conventionally, for a tubular permanent magnet synchronous linear motor (TPMSLM), adopting a modular structure can effectively reduce the detent force; however, the thrust density is sacrificed via the large proportion of the flux barrier to the total primary component volume. To overcome this disadvantage, this paper proposes a novel modular TPMSLM, in which the unit primary component adopts the large slot structure containing several coils. Focusing on this motor, research on the flux linkage characteristic is performed to obtain the design principle, and then the detent force is analyzed and suppressed by reasonable design of end teeth. First, the flux linkage characteristics of the unit motor and the whole motor are investigated. Variation rule of the coil flux linkage affected by the end tooth is discussed, and the principle of realizing three-phase balance for the whole motor flux linkage is elaborated. Moreover, the principle of the detent force suppression is verified and the detent force is further suppressed through the end tooth design. Finally, a prototype is developed. The back electromotive force and the detent force were tested, which verified the effectiveness of the novel modular TPMSLM proposed. [ABSTRACT FROM AUTHOR]

This paper focuses on the thrust ripple of a permanent magnet linear synchronous motor (PMLSM). The PMLSMs with the North–South (NS) and consequent (C) poles are compared first. Then two magnetic regulating structures whose widths are τ and τ/3 (τ is the pole pitch) are proposed and set on the primaries, forming Modulars I and II structures, respectively. The effects that the modular structures exerting on the detent force and voltage harmonics are expounded. At last the modular primaries are selectively applied to the PMLSMs with different poles: the modular I whose magnetic regulating structure employs magnetic permeable material is applied to the C-pole PMLSM, and thus the thrust ripple caused by the voltage harmonics is suppressed remarkably. Whereas the magnetic regulating structure of the modular II which is nonmagnetic is used for the NS-pole PMLSM, helping to reduce the detent force and improve the average thrust. [ABSTRACT FROM AUTHOR]

To overcome the disadvantage that the detent force of the permanent magnet linear synchronous motor (PMLSM) with short primary is large, a scheme of the modular PMLSM with flux barriers is proposed in this paper. First, the detent force model is established and verified. The phase-angle characteristics of the harmonics in the detent force waveforms are analyzed. Then, the design principles of the scheme with different sectional combinations are analyzed, and two series of the combinations are demonstrated. The detent force and thrust characteristics of these combinations are subsequently compared. In addition, to improve the thrust density, the auxiliary teeth set at the ends of the sectional primary cores are proposed. Finally, the corresponding conclusions obtained by comparing the modular motors with the traditional motor are presented. [ABSTRACT FROM AUTHOR]

The implications of the end effect for flux linkage and thrust ripple in a slot-less long-stator permanent magnet linear synchronous motor (LSPMLSM), are analyzed in this paper. Since it is affected by the end effect, the air-gap magnetic field density under the end permanent magnet is different from that under the non-end permanent magnet, leading to asymmetry in the thrust ripple. For this reason, we establish a dynamic permanent magnet flux linkage model, which proves that the end effect leads to sub-harmonics in the permanent magnet flux linkage. The motor's magnetic field distribution in the left and right parts is symmetrical. A thrust model taking into account the flux linkage sub-harmonics is established, from which the amplitude and period of the thrust ripple caused by the end effect can be calculated. There is no detent force for the slot-less LSPMLSM, and the end effect is the primary origin of the motor thrust ripple. In order to suppress the end effect, a method of increasing the end iron length is proposed, as a result of which the sub-harmonics in the flux linkage and the motor thrust ripple are effectively suppressed. Experimental and simulation results verify the results of this paper. [ABSTRACT FROM AUTHOR]