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R.N.G.P.I.T, Bardoli �Electrical Engineering Department

Subject: Electrical Machine-II

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Prepared By:

Dr. Shaikh Mohammed Suhel

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Prepared By:

  • Name: Dr. Shaikh Mohammed Suhel

(Assistant Professor RNGPIT, Surat)

  • Former Assistant Professor in SCET, SNPIT&RC, VIT
  • Qualification: PhD (Power- Electronics & Drives, NIT, Surat), M.Tech (Industrial Electronics, NIT-Surat), Gate, B.E. (Electrical Engineering., VNSGU-Surat).
  • Experience: 13 Years.

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CH: Special Machine

  • This Lecture contain
  • Theory of Switched reluctance motor

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  • By Dr. Shaikh Mohammed Suhel

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  • Switch Reluctance Motor:

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  • The switch reluctance motor (SRM) have similar principle as a variable reluctance stepper motor
  • Unlike a conventional synchronous motor, both the rotor and stator of a SRM motor have salient pole.

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  • Switch Reluctance Motor:

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  • The stator carries coin on each pole, the coil on opposite poles being connected in series.
  • The eight stator coil shown in figure are grouped to form four phases which are independently energized from a four phase converter.
  • The laminated rotor has no winding or magnet and is therefore cheap to manufacture and extremely robust.

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  • Working:

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  • Usually arrangement is to energize stator coil sequentially with a single pulse of current at high speed.
  • The motor rotates in clockwise direction when the stator phase are energized in the Sequence switching A, B C, D, A…

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A

A’

B

B’

C

C’

D

D’

1

2

3

4

5

6

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  • VR Stepper Motor:
  • It rotates in steps
  • It is designed first and foremost for open loop operation

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  • Its rotor poles are made of ferromagnetic material
  • It is capable of half step and micro stepping operation.
  • Has Low Power Rating
  • Has Lower efficiency

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  • SR Motor:
  • It is meant for continuous operation
  • Close loop operation is essential for its optimal working
  • Its rotor poles are also made of ferromagnetic material
  • It is not designed for this purpose
  • Has Power rating upto 75kW
  • Has higher overall efficiency

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  • The features of the SRM motor mainly include:

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  • It operates with a DC supply once used with an inverter.
  • Control of one phase is independent of the other phases.
  • The unutilized energy fed to the motor can be retrieved by using the feedback diodes. This improves efficiency.
  • Close loop control is essential to optimize the switching angle of the applied coil voltages.

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  • The advantages of SRM motor are as follows:

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  • Higher efficiency. More power per unit weight and volume
  • Vary robust because rotor has no winding or slip rings
  • Can run at very high speed
  • Has versatile and flexible drive features, four quadrant operation is possible

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  • The disadvantages of the SRM Motor are as follows:

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  • Relatively unproven
  • Noisy and not well suited for smooth torque production
  • The SRM motor applications are as follows:

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  • General purpose industrial drives, electric vehicle
  • Traction
  • Domestic appliances like food processors, vacuum cleaners, washing machine etc.
  • Office and business equipment

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End

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THANK YOU