Unformatted text preview: Spring 2011 EEE472/591 – Power Electronics and Power
Due: Thursday, May 03 Raja Ayyanar Problem 1: (30 points)
Suggest a suitable power electronic converter topology for each of the following applications.
Draw a rough schematic for each.
DC load Fuel cell
2V dc at 100 A
110 V AC Power
Electronic for processors.
converter (note: very low
output voltage) (a) 110 V AC
220 V AC
Electronic 400 Hz
Single phase converter Three phase (c) Power
converter 48 V
battery When the capacity of fuel cell is high, it supplies the load
and charges the battery through the converter. When the
capacity is low, the battery becomes the source and
supplies the critical load through the converter.
(b) (a) 110 V AC Power
Variable magnitude ac
Electronic voltage (0 to 110 V)
converter for light dimmers (60Hz) (d) Problem 2: (30 points)
The figure below shows a unipolar PWM converter with a switching frequency of 50 kHz.
Consider the following two cases:
Case 1: Input current is controlled to be is t 20 sin 2 50t 300 A .
Case 2: Input current is controlled to be is t 20sin 2 50t A .
+ + is
155 sin 2 50t V A 5 mH
+ B v Bn
v An 200 V + n For EACH of the two cases,
(a) Calculate the required control voltages for the two legs, vcA t and vcB t . Assume Vtri 1 V.
(b) Draw the following cycle-by-cycle averaged quantities for the time interval of 0 to 40 ms.
Assume that the operation is in steady state from t = 0. i vAn t , ii vBn t and idc t (c) Draw instantaneous vAn t , vBn t , and vAB t in the time interval of 4.98 ms to 5.02 ms.
Optional Bonus problem (30 points):
Simulate the above unipolar PWM for Case 1 and show simulation plots of the instantaneous
and CCA waveforms of the parameters required in Problem 2b and 2c. ...
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