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  1. Choppers
  2. Cycloconverters
  3. Inverters
  4. Three-phase controlled converters
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1 Answers

Option 2 : Cycloconverters

Speed control of 3ϕ induction motor:

  • The speed of an induction motor can be controlled by using cyclo converters.
  • There are two ways to control the speed of the motor, one method is by changing the frequency and the second method is by changing the number of poles.
  • In the frequency control method, a cyclo converter is controlled through the timing of its firing pulses to produce an alternating output voltage.
  • The speed control by the second method is uneconomical because under running conditions the number of poles can't be varied and the machine size becomes bulkier.

 Other methods of speed control for a 3ϕ induction motor:

1.) Control From Stator Side:

  • By changing the supply frequency
  • By changing the number of stator poles
  • By changing the supply voltage

2.) Control From Rotor Side:

  • By inserting resistance in the rotor circuit
  • By various ways of cascade connection
  • By injecting EMFs in the rotor circuit
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