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Electric Machines
Published in Patrick Hossay, Automotive Innovation, 2019
Placing an iron core in our coil can allow us to shape the magnetic force more effectively. So far, our magnetic fields have traveled entirely through air. But air is not a great conductor of MMF. In fact, it has a very high reluctance. Providing a low-reluctance conductor for magnetic flux allows us to potentially shape or concentrate the magnetic field. In fact, the ability of iron to support a magnetic field, called permeability, is roughly 1,000 times better than air. Consequently, far less of it will be lost as leakage to the surrounding air. The force produced is proportional to the flux density we can produce. Double the density and you double the force. Of course, there is a limit. Any given magnetic conductor has a maximum amount of magnetic flux it can accommodate until saturation. At this point, all the atomic dipoles in the material are lined up and no further increase in the field is possible; after that increasing the magnetic field results only in lost energy. When the core is saturated, the reluctance of the material goes up very quickly. This is typically not a major factor, as a motor’s core is typically sized to suit its purpose and operate below saturation; but it is the primary reason a larger power demand generally requires a physically larger motor.
AC Null Measurements
Published in Robert B. Northrop, Introduction to Instrumentation and Measurements, 2018
Most practical inductors are made from one or more turns of a conductor such as copper, wound as a solenoid on either an air core or a ferromagnetic core made from ferrite ceramic or laminated iron. If the coil is wound around a ferromagnetic ring or doughnut, it is called a toroidal inductor. The use of ferromagnetic cores concentrates the magnetic flux and produces a higher inductance than would be attainable with an air core and the same coil geometry. Because the conductor used to wind an inductor has a finite resistance, the simplest, LF equivalent circuit of a practical inductor is a resistor in series with a pure inductance. At very high frequencies, the small, stray capacitance between adjacent turns of the inductor’s coil produces a complex, distributed-parameter, RLC circuit. If the coil is wound with several layers of turns, capacitance between the layers, as well as between adjacent turns, and between the inner turns to the core produces a very complex equivalent circuit of the inductor at very high frequencies.
Fundamentals of Electronics and Mechanics
Published in Ferat Sahin, Pushkin Kachroo, Practical and Experimental Robotics, 2017
An inductor is an electronic component composed of a coil of wire. The magnetic properties of a coil come into effect. When a voltage is applied, a current starts flowing in the coil and a magnetic field is created as shown in Figure 1.3. While the field is building, the coil resists the flow of the current. Once the field is built, current flows normally. When the voltage is removed, the magnetic field around the coil keeps the current flowing until the field collapses. Thus, the inductor can store energy in its magnetic field, and resist any change in the amount of current flowing through it. The unit of inductance is the Henry (H). In order to increase the inductance, we can use core materials like Soft iron, Silicon iron, etc. The most common type of inductor is the Bar Coil type. The others are surface mount inductors, Toroids (ring-shaped core), thin film inductors, and transformers. The choice of inductor depends on the space availability, frequency range of operation, and certainly power requirements.
Inductance calculations for coils with an iron core of arbitrary axial position
Published in Electromagnetics, 2019
Yuanzhe Zhu, Baichao Chen, Yao Luo, Runhang Zhu
Circular coil is a basic component in most electrical equipment such as power transformers, reactors, and power filters, and it also plays an important part in some popular researches like wireless power transmission and non-destructive evaluation. In most cases, an iron core is used to improve the performance and decrease the size of circular coils because its high permeability is helpful for increasing the inductance of coils. Compared with those of closed path or narrow air gap, the cylindrical cores of finite length won’t be saturated when coils carry high currents, which is more suitable for situations where constant inductance is required (Luo and Chen 2013; Rodriguez et al. 2016; Tytko and Dziczkowski 2015, 2017).
Range extension for electromagnetic detection of subsea power and telecommunication cables
Published in Journal of Marine Engineering & Technology, 2022
T. Szyrowski, A. Khan, R. Pemberton, S. K. Sharma, Y. Singh, R. Polvara
The coil size and number of turns play a key role in the coil’s sensitivity. For this reason, air searching coils become very large and difficult to use. The miniaturisation problem is often overcome by incorporating a ferromagnetic material as the coil’s core. The core concentrates the magnetic flux inside the coil. The relative permeability of modern ferromagnetic materials often exceeds the ratio of and largely increases the coil’s sensitivity.
An arbitrary-order differentiator design paradigm with adaptive gains
Published in International Journal of Control, 2018
Markus Reichhartinger, Sarah Spurgeon
An electric current through the coil generates a magnetic field. The objective is to adjust this current such that the ball is levitated at a desired constant position r. It is well known that the dynamics can be modelled by