The reluctance motor is a type of synchronous machine. It has wound field coils of a DC motor for stator windings and has no coils or magnets in its rotor. It can be seen that both the stator and rotor have salient poles; hence, the machine is a doubly salient machine.
The Switched Reluctance Motor (SRM) is and electric motor which runs by reluctance torque. It has wound field coils as in a DC motor for the stator windings. The rotor however has no magnets or coils attached. The rotor of the motor becomes aligned as soon as the opposite poles of the stator become energized. In order to achieve a full rotation of the motor, the windings must be energized in the correct sequence. For example, if the poles a1 and a2 are energized then the rotor will align itself with these poles.
Once this has occurred it is possible for the stator poles to be de-energized before the stator poles of b1 and b2 energized. The rotor is now positioned at the stator poles b. This sequence continues through before arriving back at the start. This sequence can also be reversed to achieve motion in the opposite direction. This sequence can be found to be unstable while in operation.
A much more stable system can be found by using the following sequence, firstly the stator poles a1 and a2 are energised. The stator poles of b1 and b2 are then energised which pulls the rotor so that it is positioned between the stator poles of a and b. following this the stator poles of a are de-energised and the rotor continues on to be aligned with the stator poles b, this sequence continues through bc, c and ca before a full rotation has occurred. This sequence can also be reversed to achieve motion in the opposite direction.
Shaft position information is provided using an 8-slot disk connected to the rotor shaft and three opto- couplers mounted to the stator housing as shown in figure The opto- couplers are nominally located 300 apart from each other along the circumference of the disk. This configuration and geometry produces the output waveforms. This configuration generates an opto- coupler edge for every 7.50 of mechanical rotation. For every 450of mechanical rotation the signal pattern repeats, corresponding to one electrical cycle of the SRM, of which there are 8 per shaft revolution.
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| SRM |
The Switched Reluctance Motor (SRM) is and electric motor which runs by reluctance torque. It has wound field coils as in a DC motor for the stator windings. The rotor however has no magnets or coils attached. The rotor of the motor becomes aligned as soon as the opposite poles of the stator become energized. In order to achieve a full rotation of the motor, the windings must be energized in the correct sequence. For example, if the poles a1 and a2 are energized then the rotor will align itself with these poles.
Once this has occurred it is possible for the stator poles to be de-energized before the stator poles of b1 and b2 energized. The rotor is now positioned at the stator poles b. This sequence continues through before arriving back at the start. This sequence can also be reversed to achieve motion in the opposite direction. This sequence can be found to be unstable while in operation.
A much more stable system can be found by using the following sequence, firstly the stator poles a1 and a2 are energised. The stator poles of b1 and b2 are then energised which pulls the rotor so that it is positioned between the stator poles of a and b. following this the stator poles of a are de-energised and the rotor continues on to be aligned with the stator poles b, this sequence continues through bc, c and ca before a full rotation has occurred. This sequence can also be reversed to achieve motion in the opposite direction.
Shaft position information is provided using an 8-slot disk connected to the rotor shaft and three opto- couplers mounted to the stator housing as shown in figure The opto- couplers are nominally located 300 apart from each other along the circumference of the disk. This configuration and geometry produces the output waveforms. This configuration generates an opto- coupler edge for every 7.50 of mechanical rotation. For every 450of mechanical rotation the signal pattern repeats, corresponding to one electrical cycle of the SRM, of which there are 8 per shaft revolution.
