reluctance motor
GROUP 4 JULY 26, 2013
EE 4101 ENGR. KENNETH F. FAJILAN
Reluctance Motor
Introduction
A reluctance motor is a type of electric motor that induces non-permanent magnetic poles on the ferromagnetic rotor. Torque is generated through the phenomenon of magnetic reluctance.
There are various types of reluctance motor:
Synchronous reluctance
Synchronous reluctance motors have an equal number of stator and rotor poles. The projections on the rotor are arranged to introduce internal flux “barriers“, holes which direct the magnetic flux along the so-called direct axis. Typical pole numbers are 4 and 6.
As the rotor is operating at synchronous speed and there are no current-conducting parts in the rotor, rotor losses are minimal compared to those of an induction motor.
Once started at synchronous speed, the motor can operate with sinusoidal voltage. Speed control requires a variable-frequency drive.
Switched reluctance or variable reluctance motor
The switched reluctance motor (SRM) is a form of stepper motor that uses fewer poles. The SRM has the lowest construction cost of any industrial electric motor because of its simple structure. Common uses for an SRM include applications where the rotor must be held stationary for long periods and in potentially environments such as mining because it does not have a mechanical commutator.
The phase windings in a SRM are electrically isolated from each other, resulting in higher fault tolerance than inverter-driven AC induction motors. The optimal drive waveform is not a pure sinusoid, due to the non-linear torque relative to rotor displacement, and the highly position-dependent inductance of the stator phase windings.
Variable reluctance stepping motor
The variable-reluctance (VR) stepper motor differs from the PM stepper in that it has no permanent-magnet rotor and no residual torque to hold the rotor at one position when turned off. When the stator coils are energized, the rotor teeth will align with the energized
EE 4101 ENGR. KENNETH F. FAJILAN
Reluctance Motor
Introduction
A reluctance motor is a type of electric motor that induces non-permanent magnetic poles on the ferromagnetic rotor. Torque is generated through the phenomenon of magnetic reluctance.
There are various types of reluctance motor:
Synchronous reluctance
Synchronous reluctance motors have an equal number of stator and rotor poles. The projections on the rotor are arranged to introduce internal flux “barriers“, holes which direct the magnetic flux along the so-called direct axis. Typical pole numbers are 4 and 6.
As the rotor is operating at synchronous speed and there are no current-conducting parts in the rotor, rotor losses are minimal compared to those of an induction motor.
Once started at synchronous speed, the motor can operate with sinusoidal voltage. Speed control requires a variable-frequency drive.
Switched reluctance or variable reluctance motor
The switched reluctance motor (SRM) is a form of stepper motor that uses fewer poles. The SRM has the lowest construction cost of any industrial electric motor because of its simple structure. Common uses for an SRM include applications where the rotor must be held stationary for long periods and in potentially environments such as mining because it does not have a mechanical commutator.
The phase windings in a SRM are electrically isolated from each other, resulting in higher fault tolerance than inverter-driven AC induction motors. The optimal drive waveform is not a pure sinusoid, due to the non-linear torque relative to rotor displacement, and the highly position-dependent inductance of the stator phase windings.
Variable reluctance stepping motor
The variable-reluctance (VR) stepper motor differs from the PM stepper in that it has no permanent-magnet rotor and no residual torque to hold the rotor at one position when turned off. When the stator coils are energized, the rotor teeth will align with the energized