Force Ripple Reduction Methods for Tubular Permanent Magnet Linear Machines

Document Type : Article


1 School of Electrical and Computer Engineering, University of Hormozgan, Bandar-Abbas, Iran

2 School of Electrical Engineering, Sharif University of Technology, Tehran, Iran


This paper presents some novel force ripple reducing techniques for tubular permanentmagnet
linear machines (TPMLMs) with the square-shaped cross section. These methods are very
straightforward, so their implementation in TPMLMs with the square cross section is easy. An
analytical form of machine parameters such as the thrust force is obtained by solving the analytical
field. A modular configuration for permanent-magnet pole is used to reduce teeth cogging
force. Furthermore, the manufacturing cost of TPMLMs can be reduced by using modular pole
permanent-magnet. In this method, the width of permanent-magnets (PMs) is calculated by using
Fourier analysis and a sensitivity analysis has been conducted to identify the robustness of this
technique. Additional stator side methods are used to decrease the end face cogging force. Moreover,
the stator teeth shifting method is proposed to reduce the electromagnetic force ripples. Also,
the produced electromagnetic force of the machine is increased by using a delay in the power supply.
3 -D non-linear finite-element analyses and experimental tests are performed to investigate
the effectiveness and performance of proposed techniques.


Main Subjects