North South University
Dept. of Electrical and Computer Engineering
Mid Examination: Spring 2022
12 March 2022
EEE 312 (Power Electronics)
Sec: 1
Full Marks: 30
Time: 60 minutes
Answer ALL the THREE questions. All questions are of equal value.
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1. Draw the two-transistor model of an SCR and find the expression of anode current in
terms of the parameters of the transistors. Define latching and holding currents.
2. With neat drawing, briefly describe the operation of GTO and TRIAC. Define SCR
commutation and name the best method for it.
3. Draw circuit diagram of a half-wave controlled rectifier and draw the wave shapes of
output voltage and current for R-L load with sinusoidal input. Design a single-phase,
half-wave AC to DC converter circuit to produce an average voltage of 80 V to a 100 Ω
resistive load from a source of 200 V. If the load is a 200 W light bulb, what will
happen to the bulb?
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Attention: Follow the following Instructions for Answer Submission
1. Answer should be brief, specific and must demonstrate your understanding on the
topic (not just copy from any media). Mark will be deducted for copying from others
and late submission.
2. Use only black ball point pen and A4 size white offset paper for writing and sketch.
Don’t submit any typed copy, only Scan copy of your own hand-written answers will
be accepted. Submit it to this classroom drive as PDF (after scanning) in a single file.
3. Write Spring 2022 Mid Exam, your Name, ID No., Course Code, Course Title,
Section on the 1st page of your script.
4. Put page numbers at the bottom right of each page. Try to minimize your number of
pages.
5. Submit the scan copy of your answer to this Google Classroom within time. Write
your Student ID as the File name.
6. It is mandatory to preserve your hard copy for future submission.