What Is Stepping Motor?
A stepping motor operates using electrical impulses to coordinate its movements. In the case of this motor, the spindle moves in a sequence of steps commanded by the pulses. This type of motor can be inexpensive to operate, comes in three different types of setups and provides the user with several advantages over other, more complex types of engines.
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How It Works
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The electrical impulses do the work in driving a stepping motor. First, applied pulses determine the rotation of the motor shaft. That causes a chain reaction. The speed of the motor shaft then drives the frequency of the input pulses, which in turn influences the length of rotation for the input pulses. All of these pulses work together to generate the motor's power.
The Open Loop
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The open loop is one of the reasons those that use the stepping motor like it. An open loop operation means that the user doesn't need any feedback information from the engine about its position during use. Because of this, users can save money on sensors and other devices like optical encoders. If you're monitoring the engine, all you need to keep track of are the pulses.
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Variable Reluctance
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The Variable Reluctance Stepping Motor is the oldest type of stepper motor. It looks like two wheels, with one large wheel housing a smaller wheel. The larger wheel is the stator, and when the stator is energized by the pulses it serves as a magnet for the rotor, which is inside of the stator and made of iron. The teeth of the rotor are attracted to the stator, which prompts the motor to start running.
Permanent Magnet
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The Permanent Magnet Stepping Motor employs permanent magnets and a toothless rotor. The rotor in this engine is magnetized at the north and south end and runs parallel to the rotor shaft. Because of this, the PM motor generates more magnetic force and more torque than the Variable Reluctance motor. A PM motor is also called a "tin can" or "canstock" motor and moves at anywhere from 24 to 48 steps per revolution.
Hybrid
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The Hybrid Stepping Motor is the most expensive of the three, but is also considered the best performing motor. The engine can move at 100 to 400 steps per revolution. The reason it's a hybrid is that it is a combination of the VR and PM motors. The Hybrid uses the toothed rotor from the VR motor and a magnet surrounding the engine shaft. These two forces combine for a stepping motor with more torque and power.
Uses
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Stepping motors have several applications. They are used primarily in devices where movement is necessary, or when the motor's angle, rotation and speed must be expertly controlled. For these reasons, stepping motors are primarily used in office equipment like printers, hard disk drives and fax machines. Stepping motors can also be found in medical equipment and automobiles.
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- Photo Credit Image by Flickr.com, courtesy of R11
