Eastern Mediterranean University
Eastern Mediterranean University
Department of Electrical and Electronic Engineering
EE 442 FINAL EXAM
Date : 1 / 7 / 2002 ANSWER ALL FOUR QUESTIONS
Duration : 2 hrs. EACH QUESTION IS 25 PTS.
1-) A single-phase fully-controlled bridge converter supplies power to a resistive load with resistance RL = 10 ( from a 240 V rms 50 Hz AC source , as shown below.
a) Sketch the output voltage vo ( take ( = 90(), and find its average value as a function of the firing angle ( ( show all the steps in your derivation).(15pts)
b) Sketch the current iT1 through T1 and find its rms value for ( = 90(. (10pts)
2-) Below is shown a step-down dc-dc converter with an LC filter at its output. Diode D is ideal. Switch S is operated with duty ratio k = 0.4 at the switching frequency fs = 10 kHz. Assume that the output voltage vo = Va is constant and also the output current io = Ia is constant. Given that Va = kVs , Vs = 100 V, L = 250 (H and C = 100 (F
a) Find the minimum and maximum values of the inductor current iL
for Ia = 10A. Show all your calculations. (15pts)
b) Sketch the source current is , and find its average value.(10pts)
3-) The single-phase full-bridge inverter shown below is operated in the quasi-square-wave
( QSW ) mode ( phase displacement control ) at the frequency f = 50 Hz , with phase
shift ( between half-bridge output voltages vao and vbo . The load is an R-L load with
R=5 ( and L = 10 mH.
a) For (= ( / 2 sketch vo and find its rms value. (7pts)
b) For ( = 2( / 3 find the rms values of load current harmonic components with
orders n = 1, 3 , 5, 7.( i.e. find Ion,rms , n=1,3,5,7) (8pts)
c) Find approximately the total harmonic distortion (THD) of io using the results in
part (b).(10pts)
[pic]
4-) The three-phase half-bridge inverter shown below feeds a balanced (-connected resistive load, and is operated in the square-wave mode (pole voltages are square waves) at frequency f s .
a) Sketch line current ia (show all important current and time values) and find its rms value .(12pts)
b) Find the total average power supplied to the load (take R= 10().(13pts)
USEFUL INFORMATION :
1-) THD of a periodic waveform x (t):
[pic] Xn = n’th harmonic amplitude
2-) Fourier series of a quasi-square-wave
x
A
[pic]
-(/2 (/2
-(/2 (/2 (t
-A
-----------------------
[pic]
[pic]
[pic]
................
................
In order to avoid copyright disputes, this page is only a partial summary.
To fulfill the demand for quickly locating and searching documents.
It is intelligent file search solution for home and business.
Related searches
- eastern illinois university online degrees
- eastern michigan university high school
- eastern illinois university degrees
- eastern illinois university majors
- eastern michigan university gpa requirement
- eastern michigan university grade scale
- eastern michigan university application
- eastern michigan university graduate apply
- eastern michigan university graduate program
- eastern michigan university graduate admissions
- eastern michigan university admission office
- eastern michigan university apply