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M.E. (Control System Engg.) El-1: Advance Drives & Controls
(REVISED) [Time: Three Hours]
[Max.Marks: 80]
 Please check whether you have got the right question paper.  N.B 1) Solve two questions from each Section. 2) Assume suitable data if necessary. 3) Mathematical treatment is required wherever necessary. Section A Q.1 a)
Explain dual converter control scheme of DC separately excited motor with two fully controlled rectifiers.  b)
A 2 pole separately excited DC motor has the ratings of 220V, 100 A & 950 rpm. Resistance of armature is 0.2
. The motor has two field coils which are normally connected in parallel. It is used to drive a load whose torque is expressed as
 
 N-m where N is motor speed in rpm, speeds below & above rated are obtained by armature voltage control & by connecting the two field winding in series respectively- i)
Calculate the motor armature current & speed when the armature voltage is reduced to 90 V. ii)
Calculate the motor speed & current when filed coils are connected in series. 10 10 Q.2 a)
Explain regenerative braking & plugging or reverse voltage braking of an induction motor.  b)
Explain with neat sketches speed torque curve of DC motors for various methods of speed control. 10 10 Q.3 a)
Explain with neat diagram, the operation of brushless dc (or trapezoidal PMAC) motor
drive fed from a current regulated voltage source inverter with it’s voltage current &
torque waveforms.  b)
Explain self controlled synchronous motor drive employing load computed thyristor inverter with closed loop speed control scheme. 10 10
Section B
Q.4 a)
Explain the torque versus stepping rate characteristics of stepper motor. What are main
features of stepper motors which are responsible for it’s wide spread use.
Explain unipolar and bipolar drive curits for stapper motors. 10 10
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Q.5 a)
Why is it necessary to operate a solar panel near the maximum power points? Draw I-V & P-V characteristics of solar panel. Which motors are suitable for pump drives?  b)
Explain with neat circuit diagram the operation of dc drive with chopper control for an electric vehicle. What are the advantage of electrical vehicle over the internal combustion vehicles? 10 10 Q.6 a)
For electric traction drive the relationship between principle quantities involved in traction mechanics by using Trapezoidal & quadrilateral diagram.  b)
Explain important feature of traction drives explain PWM voltage source inverter squirrel cage induction motor drive with neat circuit diagram for D.C traction employing  poly phase A.C motors. 10 10
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