1 (a)
Give symbol and characteristics features of the following devices:

(i) SCR

(ii) GTO

(iii) TRIAC

(iv) IGBT

(v) SIT

(i) SCR

(ii) GTO

(iii) TRIAC

(iv) IGBT

(v) SIT

10 M

1 (b)
Briefly explain any five types of power electronic circuits.

10 M

2 (a)
What is the need for isolation of gate-drive circuits? Discuss the different methods of providing isolation of gate-drive circuits from power circuit.

10 M

2 (b)
Discuss the switching limits of power transistors.

10 M

3 (a)
With a neat diagram, explain the two-transistor model of a thyristor. Also derive an expression for the anode current in terms of transistor parameters ?

_{1}and ?_{2}.
8 M

3 (b)
what is the need of dv/dt and dv/dt protect on? Explain in how protection is provided.

4 M

3 (c)
With a neat circuit diagram and waveforms, explain UJT relaxation oscillator.

8 M

4 (a)
With the necessary circuit diagram waveforms and equations, explain the operation of single-phase full converter with R-L load.

10 M

4 (b)
Explain single-phase semiconverter with a neat circuit diagram, waveforms and equations.

10 M

5 (a)
What is commutation? Explain complementary communication with relevant circuit diagram and waveforms.

10 M

5 (b)
For the auxiliary commutation circuit. Calculate the value of the commutation capcitor and inductor for the following data:

V

V

_{dc}=30V, I_{L(max)}=15A , I_{off}of SCRI=20?sec.
4 M

5 (c)
With a neat circuit diagram and waveforms, explain the external pulse commutation.

6 M

6 (a)
With neat diagrams, waveforms of equations, discuss ON-OFF control and phase control of AC voltage controllers.

12 M

6 (b)
A single-phase full-wave AC voltage controller has a resistive load 20? and the input voltage is 100 V (rms), 60 Hz. The delay angles of thyristors T

Determine : (i) The rms outpur voltage : (ii) The input power factor : (iii) The average current of thyristors

(iv) The rms current of thyristors.

_{1}and T_{2}are : ?_{2}=?_{2}=?=?/2,Determine : (i) The rms outpur voltage : (ii) The input power factor : (iii) The average current of thyristors

(iv) The rms current of thyristors.

8 M

7 (a)
What is chopper? How they are classified? Briefly explain

10 M

7 (b)
With a neat circuit diagram and waveform explain impulse commulated chopper.

10 M

8 (a)
Explain single-phase half -bridge inverter with R load, with necessary circuit diagram and waveforms. Derive the equation for rms output voltage.

12 M

8 (b)
Explain the performance of inverters.

8 M

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