# reluctance motor

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## reluctance motor

[ri′lək·təns ‚mōd·ər]
(electricity)
A synchronous motor, similar in construction to an induction motor, in which the member carrying the secondary circuit has salient poles but no direct-current excitation; it starts as an induction motor but operates normally at synchronous speed.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

## Reluctance motor

An alternating current motor with a stator winding like that of an induction motor, and a rotor that has projecting or salient poles of ferromagnetic material. When connected to an alternating-current source, the stator winding produces a rotating magnetic field, with a speed of 4&pgr;f/p radians per second (120f/p revolutions per minute), where f is the frequency of the source and p the number of magnetic poles produced by the winding. When the rotor is running at the same speed as the stator field, its iron poles tend to align themselves with the poles of that field, producing torque. If a mechanical load is applied to the shaft of the motor, the rotor poles lag farther behind the stator-field poles, and increased torque is developed to match that of the mechanical load. This torque is given by the equation below,

where &phgr; is the flux per pole, determined largely by the applied voltage. The quantity dR/dδ is the rate of change of magnetic reluctance per pole with respect to δ, the angle of lag in mechanical radians. This quantity typically varies as sin pδ. Here, pδ = 2δe, where δe is the lag angle in electrical radians. Therefore, at constant torque load the rotor runs in synchronism with the stator field, with the rotor poles lagging the field poles by a constant angle. See Electrical degree

This phenomenon develops torque only at synchronous speed, and thus no starting torque is produced. For that reason, induction-motor rotor bars are usually built into the pole faces, and the motor starts as an induction motor. When the rotor speed approaches that of the magnetic field, the pole pieces lock in step with the magnetic poles of the field, and the rotor runs at synchronous speed.

Single-phase reluctance motors may be started by the methods used for single-phase induction motors, such as capacitor, split-phase, or shaded-pole starting. See Alternating-current motor, Electric rotating machinery, Induction motor, Motor, Synchronous motor

McGraw-Hill Concise Encyclopedia of Engineering. © 2002 by The McGraw-Hill Companies, Inc.
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References in periodicals archive ?
Saghaeian Nejad, "Optimal four quadrant speed control of switched reluctance motor with torque ripple reduction based on EM-MOPSO," The 6th Power Electronics, Drive Systems & Technologies Conference (PEDSTC2015), Tehran, 2015, pp.
Switched reluctance motor (SRM) has achieved good performance due to its remarkable advantages: high starting torque, wide operating speed range, and high efficiency.
Switched reluctance motor has numerous industrial applications because of its advantages like simple and robust construction, high reliability, and high efficiency operation over a wide range of speeds etc.
Krishnamurthy, "Comparative study of interior permanent magnet, induction, and switched reluctance motor drives for EV and HEV applications," IEEE Transactions on Transportation Electrification, Vol.
Bayir, "Design and implementation of switched reluctance motor driver for industrial controller", in Fourth Int.
"d-q Analysis of a Variable Speed Doubly ac excited reluctance motor." Electric Machines & Power Systems 19 (2): 125-138.
This method was applied to the speed control of a switched reluctance motor with good control effect [7].
Miller, "Vibration modes and acoustic noise in a four-phase switched reluctance motor," IEEE Transactions on Industry Applications, vol.
Design and analysis of rolled rotor switched reluctance motor. Journal of Electrical Engineering & Technology, 2006, Vol.1, No.4, pp.
ABB says up to 15% lower energy use, a significant reduction in motor maintenance costs and a drop in audible noise has been achieved with the installation of an ABB synchronous reluctance motor and drive (SynRM) package on a twin extruder application.

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