hw7_problem_472_S11 - Spring 2011 EEE472/591 – Power...

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Unformatted text preview: Spring 2011 EEE472/591 – Power Electronics and Power Management Homework 7 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. Critical DC load Fuel cell 100 V 2V dc at 100 A 110 V AC Power Power Electronic for processors. 60 Hz converter (note: very low output voltage) (a) 110 V AC Power Power 220 V AC 60 Hz Electronic 400 Hz Single phase converter Three phase (c) Power Power Electronic 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 Power Variable magnitude ac 60 Hz 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 . idc + + is 155 sin 2 50t V A 5 mH + B v Bn v An 200 V + n For EACH of the two cases, ˆ (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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