STUPIDSID
1(a)
Explain the different types of power electronic converter circuits with neat circuit diagram and input and output waveforms. Also mention its application.
8 M
1(b)
Write the symbol and characteristic features of the following devices:
i) BJT ii) TRIAC iii) GTO iv) MOSFET.
i) BJT ii) TRIAC iii) GTO iv) MOSFET.
8 M
1(c)
Discuss the peripheral effects of power electronic converters. Also write the remedies.
4 M
2(a)
For the circuit shown in Fig. Q2(a), BJT is specified to have β in the rang of 12 to 75. If Vcc = 40 V, Rc=1.5 Ω, VB = 6 V, VCE(sat)=1.2 V and VBE(sat) = 1.6 V and Rb=0.7 Ω. Calculate : i) Overdrive factor ODF ii) Forced Bf iii) Total power dissipational (PT).
7 M
2(b)
With the transient model of MOSFET explain swiching characteristics.
6 M
2(c)
What is the need for isolation for gate drive circuits? Discuss the different methods of providing isolation of gate drive circuits from power circuits?
7 M
3(a)
Explain the V-1 characterists of SCR by clearly indicating different states on characteristics. Also explain different modes of operation.
6 M
3(b)
With two transistor analogy of a thyristor obtain the equation for anode current.
6 M
3(c)
An SCR employs an R-triggering as shown in Fig. Q3(c) With Ig(min) = 0.1 mA and Vg(min) = 0.5 V. The diode is silicon and the peak amplitude of the input voltage is 24 volts. Determine the triggering angle α for R = 100 kω and Rmin = 10kω.
4 M
3(d)
A SCR has a di/dt = 50A/μsec and dv/dt = 150 V/μsec. It operates on a 100 V, calculate the snubber circuit elements using approximate expressions.
4 M
4(a)
With necessary circuit and waveforms explain the principle of operation of single phase semiconverter. Also derive an expression for the average output voltage.
6 M
4(b)
With neat circuit diagram explain the opetating principle of dual converter with and without circulating current.
8 M
4(c)
A single phase half wave controlled rectifier is used to supply power to 10 ω load from 230V, 50Hz supply at a firing angle of 30°: . Calculate (i) average output voltage (ii) effective output voltage (iii) average load current.
6 M
5(a)
What is the necessary condition for successful commutation of SCR? Compare between forced and natural commutation.
6 M
5(b)
With necessary circuit waveforms explain the working of complementary commutation. Also perform circuit analysis.
8 M
5(c)
For the impulse commutated thyristor of circuit Fig.Q5(c), determine the turn-off time of the circuit, if Vs = 200 V, R = 10 ω C= 5 μF and Vc (t=0) = Vs. Also derive te equations used.
6 M
6(a)
With the help of neat circuit and relevant waveforms explain the working of ON-OFF control, for single phase AC voltage controller with resistive load. Also derive an expression for RMS output voltage.
8 M
6(b)
A 1 ϕ half wave ac voltage controller has an input voltage of 120 V, 60 Hz and a load resistance of 10 Ω. The firing angle of thyristor is 60°. Find
i) RMS output voltage ii) Input power factor iii) Average input current.
i) RMS output voltage ii) Input power factor iii) Average input current.
8 M
6(c)
What is the problem caused by sharp single pulse triggering in a 1 ϕ AC voltage controller when the load is inductive? How can this be solved?
4 M
7(a)
Briefly explain the clalssification of choppers with circuit, waveforms and quadrant diagrams.
8 M
7(b)
For the chopper shown in below Fig. Q7(b), DC source voltage is 200 V, load resistanace is 20 ω . Consider the voltage drop of 4 V across chopper when it is ON. For a duty cycle of 0.3, calculate (i) Average and rms value of output voltage.
4 M
7(c)
Explain the operation of step down chopper with RL load. Also derive an expression of peak-peak output ripple currrent.
8 M
8(a)
Explain the principle of single phase half bridge inverter with suitable circuit and waveforms.
10 M
8(b)
Explain the performance parameters of inverter.
4 M
8(c)
Explain principle of working of variable DC link inverter. Also mention advantage and disadvantages.
6 M
More question papers from Power Electronics