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  • Question

  • In pulse width modulation of chopper


  • Options
  • A. T is kept constant and Ton is varied
  • B. Ton is kept constant T is varied
  • C. both T and Ton are varied
  • D. either T or Ton is varied

  • Correct Answer
  • T is kept constant and Ton is varied 

    • Power Electronics problems

    Search Results

    • 1. As compared to BJT, MOSFET has

    • Options
    • A. lower switching losses and higher conduction losses
    • B. higher switching losses and higher conduction losses
    • C. higher switching losses and lower conduction losses
    • D. lower switching losses and lower conduction losses
      • Discuss
    • 2. In a 3 phase full converter, the firing angle is less than 60°. The instantaneous output voltage

    • Options
    • A. will have positive part only
    • B. will have both positive and negative parts
    • C. may have both positive and negative parts
    • D. will have negative part if load is inductive
      • Discuss
    • 3. A separately excited dc motor is run from a dc source through a chopper. At 600 rpm and rated torque, the duty cycle of chopper is 0.8. At 600 rpm and half the rated torque, the duty cycle is likely to be

    • Options
    • A. 0.9
    • B. 0.8
    • C. 0.75
    • D. 0.6
      • Discuss
    • 4. If 4 quadrant operation is required we need

    • Options
    • A. dual converter
    • B. full converter
    • C. semi converter
    • D. none of the above
      • Discuss
    • 5. In a step down chopper using time ratio control, the input voltage is V and duty cycle is a. The load is purely resistive having resistance R. The average and rms load currents are

    • Options
    • A.
    • B.
    • C.
    • D.
      • Discuss
    • 6. All other parameters remaining the same, a 3 phase bridge inverter with 180° mode of operation

    • Options
    • A. has the same peak thyristor current as in 120° mode of operation
    • B. has higher peak thyristor current than in 120° mode of operation
    • C. has lower peak thyristor current than in 120° mode of operation
    • D. any of the above
      • Discuss
    • 7. A class D chopper

    • Options
    • A. can operate in first quadrant only
    • B. can operate in second quadrant only
    • C. can operate in either first or fourth quadrant
    • D. can operate in all the quadrants
      • Discuss
    • 8. In sinusoidal PWM for inverters the width of different pulses are not the same.

    • Options
    • A. True
    • B. False
      • Discuss
    • 9. When an SCR is in forward blocking mode, the applied voltage

    • Options
    • A. appears across only one junction
    • B. is equally shared by two junctions
    • C. is equally shared by three junctions
    • D. may appear across one or more junctions
      • Discuss
    • 10. In figure, thyristor Th is in off state. When thyristor is turned on, the peak thyristor current can be

    • Options
    • A. 5 A
    • B. 10 A
    • C. 15 A
    • D. 20 A
      • Discuss

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