Compare variable reluctance and permanent magnet motors.
Variable reluctance Motor
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Permanent magnet motors
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The rotor is not magnetised
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The rotor is magnetised
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High torque to inertia ratio
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Low torque to inertia ratio
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High rates of acceleration
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Low rates of acceleration
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The dynamic response is fast
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Very low dynamic response
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Maximum stepping rate can be as high as 1200 pulses per second
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Maximum stepping rate can be as low as 300 pulses per second
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If can be manufactured for large number of poles
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If can be manufactured for large number of poles due to difficulties in construction.
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Very small step angle is possible
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The step angles are high in the range of 300 to 900
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It does not have a detent torque
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It main advantage is the presence of a detent torque
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The rotor has salient pole construction
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The rotor has mostly smooth cylindrical type of construction.
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