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Reg No.: Name:

APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
SIXTH SEMESTER B.TECH DEGREE EXAMINATION(S), DECEMBER 2019

Course Code: EE308
Course Name: Electric Drives

Max. Marks: 100 Duration: 3 Hours
PARTA
Answer all questions, each ೮೮111055 marks. Marks
1 What are the functions of power modulator in an electric drive? (5)
2

A single phase fully controlled converter is used to control a DC separately (5)
excited motor of 20017, 900rpm,100A with armature resistance of 0.06Q. AC
source voltage is 210V, 50Hz. Determine firing angle for rated motor torque and
700rpm.

3 With detailed analysis explain how chopper helps to control a separately excited (5)

DC motor drive in motoring mode

4 How speed of the induction motor can be controlled using stator frequency (5)
control.
5 Differentiate VSI fed induction motor drive with CSI fed induction motor drive (5 )
6 Explain field orientation control of induction motors. (5)
7 Explain in detail about the different types of PM synchronous motor? (5)
8 Explain how speed control can be done in a set of multiple synchronous motors (5)
PART B
Answer any two full questions, each carries10 marks.
9 9) Illustrate four quadrant operation of drive considering hoist as an example (6)
b) Draw the Torque — Speed characteristics of the following loads (4)

(1) Centrifugal pump (14) Traction load
10 a) With the help of block diagram explain in detail about the closed loop speed (5)
control of DC motor
b) Draw the armature voltage and armature current waveforms of 3 phase semi- (5)
converter-fed DC motor drive for a=60°.
11 a) Give one application of dual converter for speed control of DC motor. (5)
b) A 220V, 1500rpm, 504 separately exited motor with armature resistance of (5)

0.5Q is fed from a circulating current mode dual converter with a source voltage

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