Rate my site. Not bad. Answers: Results Archive. There is a zip error in the archive, after downloading it becomes Jones Mark A. Juds University of Iowa Secs. Judd Judd Consulting Associates Secs. King H. Kokal Dana Corporation Sec. Krause Magnetics International, Inc. Miller Software and motor designer Secs. Payne Windamatics Systems, Inc. Richards University of Missouri Secs. Setbacken Karl H. Schultz Renco Encoders, Inc.
Stupak Jr. Chris A. Swenski Oersted Technology Corporation Sec. Walters Oberg Industries Sec. There was information available from a variety of sources.
There were many capable people in the field who could contribute, and there was historical data from many sources. The intent of this book is to cover the operating theory, practical design approaches, and manufacturing methods for the most common motors now in use.
We have tried to meet this intent by including as much information as possible. The universe of motor information is huge, although most of the information is old.
It became apparent that much information would have to be left out. We tried to include the basics along with that information we felt was most necessary and useful to those designing, manufacturing, and using motors. This is not a design course or a highly theoretical text but a place where people can go to get practical answers.
We are setting up a section at our Web site, www. This page intentionally left blank. Included among them are Dr. Cyril G. Veinott, Professor Philip H. Trickey, Dr. Ben Kuo, Dr. Duane Hanselman, and those authors who have contributed to this handbook.
There is, however, one person of whom I must make special mention. He is Dr. This man never ceases to amaze me. He is always willing to help out selflessly with projects of this type. I have taught many motor design courses with him. When a student asks questions of him, he can start at the lowest level of understanding necessary and develop in a very understandable way a logical and reasonable answer to the question.
His ability to communicate and teach is truly amazing. He has been very helpful in the preparation of this book.
I also need to acknowledge the dedication of my secretary, Kristina Wodzinski. Without her tireless effort this work would not have been completed. Juds Earl F. Richards William H. Yeadon Electric motors convert electrical energy into mechanical energy by utilizing the properties of electromagnetic energy conversion. The different types of motors operate in different ways and have different methods of calculating the performance, but all utilize some arrangement of magnetic fields. Understanding the concepts of electromagnetics and the systems of units that are employed is essential to understanding electric motor operation.
The first part of this chapter covers the concepts and units and shows how forces are developed. Nonlinearity of magnetic materials and uses of magnetic materials are explained. Energy and coenergy concepts are used to explain forces, motion, and activation.
Finally, this chapter explains how motor torque is developed using these concepts. These systems are briefly described as follows. Meter, kilogram, second. Centimeter, gram, second. Juds, Eaton Corporation. CGS with electric quantities in esu and magnetic quantities in emu.
Rationalized mks. Rationalized cgs. The rationalized mks and the rationalized cgs systems of units are the most widely used.
These systems are defined in more detail in the following subsections. In this system, the flux density B is defined first before H is defined , and is based on the force between two current-carrying wires. A distinction is made between B and H in empty free space, and the treatment of magnetization is based on amperian currents equivalent surface currents. No distinction is made between B and H in empty free space, and the treatment of magnetization is based on magnetic poles.
The unit emu is equivalent to an erg per oersted and is understood to mean the electromagnetic unit of magnetic moment. This material was called Magnes for the district of Magnesia, and is a naturally magnetic form of magnetite Fe3O4 , more commonly known as lodestone.
If any tiny compass needles are placed around the bar magnet, they will line up to reveal the magnetic field shape of the bar magnet. Connecting lines along the direction of the compass needles show that the magnetic field lines emerge from one pole of the bar magnet and enter the opposite pole of the bar magnet. These magnetic field lines do not stop or end, but pass through the magnet to form closed curves or loops. By convention, the magnetic field lines emerge from the north magnetic pole and enter through the south magnetic pole.
Two permanent magnets will attract or repel each other in an effort to minimize the length of the magnetic field lines, which is why like poles repel and opposite poles attract. Hans Oersted discovered in that a compass needle is deflected by an electric current, and for the first time showed that electricity and magnetism are related. The magnetic field around a current-carrying wire can be examined by placing many tiny compass needles on a plane perpendicular to the axis of the wire.
This shows that the magnetic field lines around a wire can be envisioned as circles centered on the wire and lying in planes perpendicular to the wire. The direction of the magnetic field around a wire can be determined by using the right-hand rule, as follows see Fig.
The fingers of your right hand curl around the wire to point in the direction of the magnetic field. To summarize: 1. Magnetic field lines emerge from the north magnetic pole of a permanent magnet. Magnetic field lines encircle a current-carrying wire. The right-hand rule is used with current flowing from positive to negative and with the magnetic field lines emerging from the north magnetic pole.
Courtesy of Eaton Corporation. In the electrical analogy, a voltage V provides the electromotive force that pushes an electrical current I through a region. The amount of voltage required per amp is called resistance R. Figure 1. Each turn of the coil is linked to the 10 magnetic flux lines, like links in a chain. Cournetomotive force per unit of magnetic tesy of Eaton Corporation. The permeability can also be obtained graphically from the magnetization curve shown in Fig. All systems obey the first law of thermodynamics, which states that energy is conserved.
This means that energy is neither created nor destroyed. This energy balance is illustrated in the following equation. The input electrical energy can be calculated by integrating the coil voltage and current over time, as follows. As can be seen in Fig. The stored magnet field energy is calculated by integrating Eq.
By inspection of Eq. The stored magnetic field energy can be calculated for linear materials by substituting Eq. The stored magnetic field energy Wf is derived from Eq.
The magnetic coenergy Wco is represented by the area under the curve, and can be derived by starting with Eq. A comparison of Eqs. The mechanical forces and torques produced by electromagnetic actuators are derived using the energy balance from Eq. A graphical representation for the electromechanical energy conversion is shown in Fig. The change in flux path length represents mechanical motion, which implies that there is a change in the mechanical energy.
The change in the magnetization curve from flux path length l1 to l2 reflects a change in the inductance, as described in Eqs. The change in electric energy and the change in stored magnetic field energy are defined as follows. The reluctance actuator shown in Fig. The saturable iron regions of the actuator include the armature, which moves in the x direction, two stationary poles, and a coil core.
The magnetic flux generally remains in the iron regions; however, it must cross air gap 1 and air gap 2 to reach the armature.
Some of the magnetic flux finds alternative air paths which bypass the armature; these flux paths are called leakage flux paths. The first step in constructing an equivalent reluctance model is to identify each iron flux path and each air flux path for the actuator.
By observing the expected paths of the magnetic flux Fig. The coil is shown as an amp-turn NI source in series with the core reluctance Fig.
The x-direction force on the armature can now be determined by calculating the change in the magnetic coenergy as a function of armature displacement in the x-direction. The magnetic coenergy can be calculated for the entire actuator or for just the working air gaps. Magnetic Coenergy Applied to the Entire Actuator. In general, the magnetic coenergy is calculated from Eq. However, the magnetic properties for ferromagnetic materials are normally published in terms of the magnetic flux density B and magnetic field intensity H, as B-H curves.
Therefore, the magnetic coenergy in each of the iron reluctances must be calculated by integrating the area under the B-H curve, as follows. The total magnetic coenergy in the iron is the summation of the iron coenergies. The magnetic coenergy in each of the air reluctances can be calculated from Eq. The total magnetic coenergy in the air is the summation of the air coenergies. Since the armature force is produced across the working air gaps gap 1 and gap 2 , the armature force can be determined by considering the coenergy change in the working gaps alone.
The total magnetic coenergy in the working air gaps is the summation of the air gap coenergies from Eqs. The key equations from these sections are listed here. Therefore, the flux path is very well defined because it has the same geometry as the steel parts. In general, the magnetic flux in the air is perpendicular to the steel surfaces and spreads out into a wide area.
Covering topics ranging from motor energy and efficiency to computer-aided design and equipment selection, this reference. Encyclopedia of 20th-Century Technology. Comprised of essays arranged alphabetically, most on individual objects, artifacts, techniques, and products, this is an up-to-date reference work for all those involved in teaching or researching the history of twentieth-century technology, as well as the serious general reader.
The core of each of the main entries is a. Handbook of Small Electic Motors Contact us Today Email Us: yes yeadoninc. All rights reserved.
Yeadon Engineering Services, P. A complete, definitive source for the design, manufacture, application, and testing of small electric motors less than ten horsepower.
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