Sunday, July 12, 2009

Linear Motor and Linear Stepper Motors

What is a Linear Motor?

Author: Alexis Gibrault

A linear motor is-simply speaking-an electric motor that uses a linear force mechanism to generate the power needed for a said application. In contrast to a rotational electric motor (found in automobiles, appliances, and commonly-used electrical equipment), a linear motor generates its energy output through exclusively linear scientific principles; i.e. there is no torque or rotation to produce accelerated force through the electrical current magnetic field relationship. Linear motors are used for a variety of purposes, which include high velocity trains, military weaponry, spacecraft exploration, robotic technologies, medical advancement, and automated engineering systems whose job is to produce mass amounts of a specified product.

There are two basic types of linear motors: low-acceleration and high-acceleration. Low-acceleration motors are typically used for applications in which endurance is favored over high bursts of electromechanical power or energy. These types of linear motors are engineered for Maglev trains, automated applications systems, etc. High-acceleration motors are the more common of the two, and produce higher velocity outputs for shorter amounts of time; such as used in firearms, military equipment, spacecraft propulsion, and the like. Low-acceleration linear motors are designed to accelerate an object up to a continuous stabile speed, while high-acceleration linear motors will accelerate an object up to a very high speed and then release the object. Typically, the low-acceleration linear motor will be engineered with one winding system on one side of the motor and magnets on the other side to create the electromagnetic repulsion necessary for successful application force; this is called linear synchronous design. The high-acceleration linear motor will generally be constructed of a three-phase winding on one side and a conductor plate on the other side of the motor to meet the intended engineering objective; this is called linear induction design.

Linear motors offer a number of advantages in this ever-evolving technological world. Whether the high power application your company or organization requires necessitates a low- or high-accelerated lateral motor system, linear motors assure faster acceleration and higher velocities as well as higher success rates in automated accuracy, repeatability, and long-term reliability.

About the Author:

Alexis Gibrault has written a number of informative articles on linear motors, types, and uses, as well as discussions on other facets of technology engineering. For more information on linear motors and examples of, please visit: Airex Corporation Linear Motors

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Linear Stepper Motors Technology

Author: Gordon Petten

A linear induction motor is made up of an inductor which is made of individual cores with a concentrated polyphase. Linear motors can be directly substituted for ball screw drives, hydraulic drives, pneumatic drives, or cam drives.

A linear induction motor is basically what is referred to by experts as a "rotating squirrel cage" induction motor. The difference is that the motor is opened out flat. Instead of producing rotary torque from a cylindrical machine it produces linear force from a flat machine. The shape and the way it produces motion is changed, however it is still the same as its cylindrical counterpart. There are no moving parts, however and most experts don't like that. It does have a silent operation and reduced maintenance as well as a compact size, which appeals many engineers. There is also a universal agreement that it has an ease of control and installation. These are all important considerations when thinking about what type of device you want to create. The linear induction motor thrusts ratio varies depending mainly on the size and rating. Speeds of the linear induction motor vary from zero to many meters per second. Speed can be controlled. Stopping, starting and reversing are all easy. Linear induction motors are improving constantly and with improved control, lower life cycle cost, reduced maintenance and higher performance they are becoming the choice of the experts. Linear motors are simple to control and easy to use. They have a fast response and high acceleration. Their speed is not dependant on contact friction so it is easier to pick up speed quickly.

Stepper motors are a special kind of motor that moves in discrete steps. When one set of windings is energized the motor moves a step in one direction and when another set of windings is energized the motor moves a step in the other direction. The advantage of stepper motors that the position of the motor is "known". Zero position can be determined, if the original position is known.

Stepping motors come in a wide range of angular resolution and the coarsest motors typically turn 90 degrees per step. High resolution permanent magnet motors are only able to handle about 18 degrees less than that. With the right controller stepper motors can be run in half-steps, which is amazing.

The main complaint about the stepper motor is that it usually draws more power than a standard DC motor and maneuvering is also difficult.

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Linear Motors and Stepper Motors

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