Download meepe 102 advanced power semiconductor devices

M.TECH DEGREE EXAMINATION
First Semester
Model Question Paper - II
Branch: Electrical and Electronics Engineering
Specialization: Power Electronics
MEEPE 102 ADVANCED POWER SEMICONDUCTOR DEVICES
Time: Three hours
(2013 Admissions)
(Answer all Questions)
Max. Marks: 100
1(a)Explain the term Safe Operating Area associated with power devices.
(5)
(b)Explain the forward and reverse characteristics of a Power diode.
(5)
(c)Draw and explain the reverse recovery characteristics of a Power diode.Also derive the expressions
for reverse recovery time and peak inverse current.
(15)
OR
2 (a)Explain the construction and principle of operation of a Schottky diode.
(10)
(b) Explain the EMI phenomenon due to switching.What are the different methods to reduce it. (15 )
3(a)Explain the phenomenon of secondary breakdown in transistors.
(5)
(b)What are the advantages and disadvantages of Power Darlingtons.
(5)
(c) The various parameters of a transistor circuit
areVCC=220V,VCE(sat)=2V,ICS=80A,td=0.4µs,tr=1µs,tn=50 µs, ts=3µs,tf=2µs,to=40µs and
fs=5kHz.Thecollector-to-emitter leakage current is ICEO=2mA. Determine the power loss due to collector
current (a) during ton = td + tr , (b)during conduction period tn, (c) during turn off toff = ts + tf , (d) during off
time to and (e) total average power losses PT , (f) Plot the instantaneous power due to collector current
Pc(t).
(15)
OR
4 (a)Explain the Two-transistor model of Thyristor
(10)
(b)Explain the gate and switching characteristics of an SCR
(10)
(c)Compare BJT and Thyristor
(5)
5 (a)Explain the construction of a power MOSFET
(10)
(b)Draw and explain the static and switching characteristics of power MOSFET
(10)
(c) Explain the basic structure of an MCT
(5)
OR
6 (a)Explain the basic structure of an IGBT
(10)
(b)Draw and explain the static and switching characteristics of IGBT
(10)
(c)Explain the basic principle of operation of a GTO
(5)
7 (a)Explain the overvoltage,overcurrent and gate protection schemes for thyristors.
(20)
(b)A thyristor is controlling the power in a load resistance connected in series.The supply voltage is
240V dc and the specified limits for di/dt and dv/dt for the SCR are 50A/µs and 300V/µs respectively.
Determine the values of the di/dt inductance and the snubber circuit parameters Rs and Cs.
(5)
OR
8 (a) Explain the electrical analogy of thermal components in an SCR
(10)
(b) Discuss the thermal equivalent circuit in transient heat transfer and the transient thermal
impedance.
(15)