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Reluctance Motor The reluctance motor is an electric motor in which torque is produced by the tendency of its moveable part to move to a position where.

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Presentation on theme: "Reluctance Motor The reluctance motor is an electric motor in which torque is produced by the tendency of its moveable part to move to a position where."— Presentation transcript:

1 Reluctance Motor The reluctance motor is an electric motor in which torque is produced by the tendency of its moveable part to move to a position where the inductance of the excited winding is maximized.

2 Reluctance Motor The reluctance motor is a type of synchronous machine. It has wound field coils of a DC motor for its stator windings and has no coils or magnets on its rotor. It can be seen that both the stator and rotor have salient poles; hence, the machine is a doubly salient, singly excited machine.

3 Switched Reluctance Motor
In SRM the term “ Switched Reluctance” does not mean that the Reluctance itself is switched, but it refers to the switching of phase current which is essential for the operation of the motor. It has simple mechanical construction and does not require permanent magnet for its operation. The stator and rotor in a SR motor have salient poles. The number of poles presence on the stator depends on the number of phases the motor is designed to operate in. Normally, two stator poles at opposite ends are configured to form one phase. In this configuration, a 3-phase SR motor has 6 stator poles.

4 Switched Reluctance Motor
The number of rotor poles are chosen to be different to the number of stator poles. A 3-phase SR motor with 6 stator poles and 4 rotor poles is 6/4 3-Phase SR motor. SR motor has the phase winding on its stator only. Concentrated windings are used. The windings are inserted onto the stator poles and connected in series to form one phase of the motor. In a 3-Phase SR motor, there are 3 pairs of concentrated windings and each pair of the winding is connected in series to form each phase respectively.

5 Switched Reluctance Motor
The mechanical structure of a 6/4 3-Phase SR motor is shown in Figure 1. Other configurations of SR motor such as 4/2 2-Phase SR motor (with irregular rotor) and 8/6 4-Phase SR motor are shown in Figure 2 and Figure 3.

6 Switched Reluctance Motor
The flux linkage, inductance and torque characteristics of a SR motor vary with the rotor position (i.e. the relative position of the rotor pole with the stator pole). The characteristics are in cyclic nature and repeated at every rotor pole pitch. Figure 4 a shows the rotor pole 'a' is unaligned with stator pole 'A'. Figure 4b shows the same rotor pole in a new unaligned position with the stator pole 'A' after a rotation of 90 degree in clockwise direction. The angle between these two positions is defined as the rotor pole pitch.

7 Switched Reluctance Motor
Fig 4-a Fig 4- b

8 Switched Reluctance Motor
CONSTRUCTION STATOR The stator is made up of silicon steel stampings with inward projection. Most of the motors have even number of poles. These poles carry field coils. The field coils of opposite poles are connected in series so that their mmf are additive. They are Phase windings. The ends of the phase windings are connected to the terminals of motor. These terminals are connected to the output terminals of power semiconductor switching circuitry , whose inputs is a dc supply Long narrow poles tends to produce the best designs by reducing the effects of end winding inductance and resistance.

9 Switched Reluctance Motor
CONSTRUCTION ROTOR The rotor is also made up of silicon steel stampings with outward projected poles. Rotor carries no windings or magnet. Stator poles Rotor poles- 4 The shaft carries a RPS. The turning ON & OFF of the various devices in the semiconductor switching circuitry is influenced by the signals obtained from the RPS because the SRM is normally operated with shaft position feedback in order to suitably excite the required phase windings with respect to precise rotor position.


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