Research on Segmented Primary Consequent-Pole Permanent Magnet Linear Synchronous Motor with Symmetric and Periodic End Force

The end force of North-South permanent magnet linear synchronous motor (NS-PMLSM) fluctuates symmetrically with a period of one pole. Different from it, the end force’s fluctuation cycle of the consequent-pole permanent magnet linear synchronous motor (CP-PMLSM) is usually two poles and asymmetrical. Especially, within two half cycles, the end force presents complex asymmetric characteristics. In this paper, a piecewise function model of the end force of CP-PMLSM is established. Then a primary segmented design method for adjusting the period, symmetry and phase of the end force waveform is proposed. The two-segment and grouped four-segment modular distances are combined and matched to eliminate the odd-numbered harmonics of the end force and suppress the thrust ripple. A slotless primary core experimental platform and a slotted CP-PMLSM prototype are manufactured and tested to verify the theoretical analysis and simulation results.

Rotor Position Recognition Technology of Permanent Magnet Linear Synchronous Motor Based on Sliding Mode Observer

Position sensorless control system of permanent magnet linear synchronous motor has some advantages: simple structure, easy maintenance, high efficiency, good speed performance, etc. This paper designed a position sensorless control system of permanent magnet linear synchronous motor based on sliding mode observer, namely taking advantage of a sensorless algorithm to estimate the pole position and speed. Firstly, the principle of sliding mode control and basic conditions which need to achieve are analyzed. And then, a sliding mode observer of the permanent magnet linear synchronous motor sensorless control system is designed. The related simulation model is built to study the effect of sliding mode observer for rotor position accuracy. The simulation model is implemented to build models of permanent magnet linear synchronous motor vector control system based on sliding mode observer and simulate the control performance of position sensorless control. In the last part, the feasibility of the design scheme is verified by analysis of simulation results.

End Effect Analysis of a Slot-Less Long-Stator Permanent Magnet Linear Synchronous Motor

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.