Maglev: Magnetic Fields

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.INTRODUCTION

Magnetic levitation is the latest in transportation technology and has been the interest of many countries around the world. The idea has been around since 1904 when Robert Goddard, an American Rocket scientist, created a theory that trains could be lifted off the tracks by the use of electromagnetic rails. Many assumptions and ideas were brought about throughout the following years, but it was not until the 1970’s that Japan and Germany showed interest in it and began researching and designing.

The motion of the Maglev train is based purely on magnetism and magnetic fields. This magnetic field is produced by using high-powered electromagnets. By using magnetic fields, the Maglev train can be levitated above its track, or guideway, and propelled forward. Wheels, contact with the track, and moving parts are eliminated on the Maglev train, allowing the Maglev train to essentially move on air without friction. [pic]

FIGURE[1]
BASIC PRINCIPLE OF MAGLEV TRAIN

Maglev can be used for both low and high speed transportation. The low speed Maglev is used for short distance travel. Birmingham, England used this low speed transportation between the years of 1984 and 1995. However, engineers are more interested in creating the high-speed Maglev vehicles. The higher speed vehicle can travel at speeds of nearly 343mph or 552 km/h. Magnetic Levitation mainly uses two different types of suspension, which are Electromagnetic Suspension and Electrodynamic Suspension. However, a third suspension system (Intuctrack) has recently been developed and is in the research and design phase. These suspension systems are what keep the train levitated off the track.

PROPULSION SYSTEM

ELECTRODYNAMIC PROPULSION IS THE BASIS OF THE MOVEMENT IN A MAGLEV SYSTEM. THE BASIC PRINCIPLE THAT ELECTROMAGNETIC PROPULSION FOLLOWS IS THAT “OPPOSITE POLES ATTRACT EACH OTHER AND LIKE POLES REPEL EACH OTHER”. THIS MEANING THAT THE NORTH POLE OF A MAGNET WILL REPEL THE NORTH POLE OF A MAGNET WHILE IT ATTRACTS THE SOUTH POLE OF A MAGNET. LIKEWISE, THE SOUTH POLE OF A MAGNET WILL ATTRACT THE NORTH POLE AND REPEL THE SOUTH POLE OF A MAGNET. IT IS IMPORTANT TO REALIZE THESE THREE MAJOR COMPONENTS OF THIS PROPULSION SYSTEM. THEY ARE: • A large electrical power source

• Metal coils that line the entire guideway
• Guidance magnets used for alignment
The Maglev system does not run by using a conventional engine or fossil fuels. The interaction between the electromagnets and guideway is the actual motor of the Maglev system. To understand how Maglev works without a motor, we will first introduce the basics of a traditional motor. A motor normally has two main parts, a stator and a rotor. The outer part of the motor is stationary and is called the stator. The stator contains the primary windings of the motor. The polarity in the stator is able to rapidly change from north and south. The inner part of the motor is known as the rotor, which rotates because of the outer stator. The secondary windings are located within the rotor. A current is applied to the secondary wingings of the rotor from a voltage in the stator that is caused by a magnetic force in the primary windings. As a result, the rotor is able to rotate. Now that we have an understanding of how motors work, we can describe how Maglev uses a variation on the basic ideas of a motor. Although not an actual motor, the Maglev’s propulsion system uses an electric synchronous motor or a linear synchronous motor. The Maglev system works in the same general way the compact motor does, except it is linear, “meaning it is stretched as far as the track goes”. The stators of the Maglev system are usually in the guiderails, whereas the rotors are located within the electromagnetic system on the train. The sections of track that contain the stators are known as stator packs. This linear motor is essential to any Maglev system. The picture...
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