What is Electric Motor ?

7.5 kW/kg. This yokeless axial flux motor offers a shorter flux path, keeping the magnets further from the axis. The design allows zero winding overhang; 100 percent of

the windings are active. This is enhanced with the use of rectangular-section copper wire. The motors can be stacked to work in parallel. Instabilities are minimized by

ensuring that the two rotor discs put equal and opposing forces onto the stator disc. The rotors are connected directly to one another via a shaft ring, cancelling out the

magnetic forces.[80]

Magnax motors range in size from .15–5.4 metres (5.9 in–17 ft 8.6 in) in diameter.[80]

Servo motor

A servomotor is a motor, very often sold as a complete module, which is used within a position-control or speed-control feedback control system. Servomotors are used

in applications such as machine tools, pen plotters, and other process systems. Motors intended for use in a servomechanism must have well-documented

characteristics for speed, torque, and power. The speed vs. torque curve is quite important and is high ratio for a servo motor. Dynamic response characteristics such

as winding inductance and rotor inertia are also important; these factors limit the overall performance of the servomechanism loop. Large, powerful, but slow-

responding servo loops may use conventional AC or DC motors and drive systems with position or speed feedback on the motor. As dynamic response requirements

increase, more specialized motor designs such as coreless motors are used. AC motors' superior power density and acceleration characteristics compared to that of

DC motors tends to favor permanent magnet synchronous, BLDC, induction, and SRM drive applications.[79]

A servo system differs from some stepper motor applications in that the position feedback is continuous while the motor is running. A stepper system inherently

operates open-loop—relying on the motor not to "miss steps" for short term accuracy—with any feedback such as a "home" switch or position encoder being external to

the motor system.[81] For instance, when a typical dot matrix computer printer starts up, its controller makes the print head stepper motor drive to its left-hand limit,

where a position sensor defines home position and stops stepping. As long as power is on, a bidirectional counter in the printer's microprocessor keeps track of print-

head position.

Stepper motor

Stepper motors are a type of motor frequently used when precise rotations are required. In a stepper motor an internal rotor

containing permanent magnets or a magnetically soft rotor with salient poles is controlled by a set of external magnets that are

switched electronically. A stepper motor may also be thought of as a cross between a DC electric motor and a rotary solenoid.

As each coil is energized in turn, the rotor aligns itself with the magnetic field produced by the energized field winding. Unlike a

synchronous motor, in its application, the stepper motor may not rotate continuously; instead, it "steps"—starts and then quickly

stops again—from one position to the next as field windings are energized and de-energized in sequence. Depending on the