IEEE TRANSACTIONS ON MAGNETICS, VOL. 50, NO. 11, NOVEMBER 2014 8600404 Analytical and Experimental Modeling and Simulation of a Magnetic Braking System for Pipeline Oil Applications Ricardo F. Pinheiro Filho, Andrés O. Salazar, Francisco E. C. Souza, and Paulo L. B. da Silva Federal University of Rio Grande do Norte, Natal 59072-970, Brazil This paper presents a study on the braking effect of the electromagnetic forces produced by eddy currents induced in nonmagnetic materials. The purpose of this paper analyzes the behavior of a moving device within ducts when a constant magnetic field is applied on its inner surface, causing induction of eddy currents in pipeline walls, and verifies how the interaction effects of these currents with the field that induced them might be significant on the device movement. Index Terms— Analytical models, eddy currents, electromagnetic devices, pipelines. I. I NTRODUCTION T HE eddy currents induction effect is a problem in electro- magnetic devices. But, the brake effect associated to this currents interaction with magnetic fields through Lorentz force opens a larger range of applications [1], [2]. Magnetic brakes are widely used in drive systems powered by electric machines, bullet trains, and automotive systems. Currently, eddy currents has been also applied in many systems, metal detectors, and most varied sensors, as in the case of verifying the integrity of oil and gas pipelines. The velocity of the pipeline instrumented gadgets (PIGs) should to be maintained between 1 and 5 m/s. However, this movement is only provided by the fluid pressure behind the device and its velocity control is hampered by obstacles formed by material deposition along the line. This leads to interruptions in PIG travel and a later shot caused by pressure increase when the device is stopped by an obstacle. This shot becomes a problem for monitoring the integrity of the pipes because of the speed increment, above acceptable limits for proper operation of the sensors instruments. This paper deals with an analysis of a brake system to be embedded in PIGs with purposes to get control of its velocity through the pipes. The braking effect and control of the velocity of a small vehicle that moves over a nonmagnetic surface will be stud- ied by development of analytical models, simulations pro- vided by engineering support software using finite element method (FEM), and experimental prototype testing. The pro- posed PIG braking system, formed by an arrangement of electromagnets is illustrated in Fig. 1, the mechanical structure of the experimental prototype is shown in Fig. 3, and the analytical modeling will be performed from its parameters, which are specified in Table I and illustrated in Fig. 2. II. SYSTEM DESCRIPTION The system developed for this paper is a small-scale vehicle that runs over a steel flat bar used as rail, having an embedded Manuscript received March 5, 2014; accepted May 26, 2014. Date of current version November 18, 2014. Corresponding author: R. F. P. Filho (e-mail: ricfilho@gmail.com). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TMAG.2014.2328520 Fig. 1. Mechanical structure arrangement proposed to the PIG brake system. electromagnet with E-shaped core. The vehicle that runs over the rail and simulation model are implemented to emulate the interaction of one of the electromagnetic units with the inner surface of the pipeline in which the proposed system will shift. The steel rail is a flat bar with low reluctance that will be used as a guide shift for the vehicle, carrying the elec- tromagnet, which will interact with a nonmagnetic (and low resistivity) copper plate positioned between electromagnet poles and the guide plate, as shown in Figs. 2 and 3. This steel flat bar will attract the field generated by the electromagnet, thereby reducing the system reluctance and leading a greater amount of flux lines through the conducting plate, increasing the flux intensity therethrough and the field skin depth, and reducing the skin effect which minimizes the induced currents. Thus, the system and its skin effect nonlinear phenomenon can be approximated by a simpler model. III. MODELING AND SIMULATION ANALYSIS Figs. 3 and 4 show the full system arrangement, which is driven by gravity load on the braking train (  P). The magnetic flux moving over the metallic surface induces eddy currents, 0018-9464 © 2014 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.