# Linear Motor

A linear motor is an asynchronous electric motor that has been developed so that instead of generating a rotating torque it generates a linear displacement. To get it distributes your stator and its rotor distributed differently.

The most common mode of operation is like a Lorentz actuator. In this mode the applied force is linearly proportional to the electric current and to the magnetic field

Linear motors are divided into two main groups:

• Slow acceleration linear motors used in Sky Train transport, Maglev, etc.
• Quick acceleration linear motors used in weapons such as magnetic cannon and space devices.

In the same category are electromagnetic induction pumps that allow conductive fluids to circulate. The first tests were made with mercury, then with a mixture of sodium and potassium, in view of the circulation of sodium for cooling in some nuclear power plants.

## Types of Linear motors

Linear motors can be classified into four distinct types: linear induction motors, linear synchronous motors, homopolar linear motors and piezo linear motors.

## Induction motor

In the design of linear induction motors, the force is produced by displacing a linear magnetic field acting on conductors in the field. In any driver placed in this field, eddy currents will be induced. The conductors may be, for example, be a winding, winding or simply a piece of metal. These currents of Foucault create an opposite magnetic field, according to determines the law of Lenz. The two opposing magnetic fields will repel each other, creating motion as the magnetic field sweeps the metal.

### Synchronous linear motors

In the synchronous linear motor design, electronic devices are generally used. These devices control the speed of movement of the magnetic field to regulate the movement of the rotor. Linear synchronous motors rarely use switches to reduce costs. For this reason, the rotor often contains permanent magnets, or soft iron. Some examples of such engines are coilguns and motors used in maglev systems.

### Homopolar linear motors

In homopolar linear motors, a high current is passed through a metal sabot by sliding contacts. These contacts are fed from two rails. This action produces a magnetic field that causes the metal to project along the tracks.

### Piezoelectric motors

A piezoelectric motor is a frequent type of motor that uses electricity to produce vibrations in a way that produces a linear or rotary motion.

A mobile recreates a similar effect when it moves due to vibrations when it receives a call.

Piezoelectric motors are very strong in slow movements, but they can also be very fast, have very few parts, do not need lubrication and are very energy efficient. It has the disadvantage that they can not rotate freely when they are stopped.

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Published: March 13, 2017
Last review: March 13, 2017