EE362L_Fall09_Tests

EE362L_Fall09_Tests - KI: EE362L, Fall 09, Test 1. Two...

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Unformatted text preview: KI: EE362L, Fall 09, Test 1. Two Problems. Name: Spa/Wis flfl- ,, Y, Show all work on these pages. One sheet of notes permitted. Do not unstaple. m Problem 1. A 120V ‘ 0Hz wall outlet voltage powers a lossless DBR, which in turn :1 / W supplies power to a laptop computer. The computer draws a constant 25W. Suppose that there is a sudden outage of AC voltage. The DBR capacitor continues to supply 25W to the computer, but when capacitor voltage Vdc falls to W, the computer shuts off. Thailapsed time is known as ride-through capability. / 00 Assuming negligible voltage ripple on the capacitor, how many uF are needed to provide 15 —-—-——-.., seconds of ride-through capability? , §+o£m€ 64/625? [/12 ‘/’£€ bet/‘62? Mme/£5 +Ae, pow/m. WED/a ktha cave-famL 60 we? IM‘C/ Z. 2 / J2 C(mG "'” VMW) : Gaga" i7 EE362L, Fall 09, Test 1. Two Problems. Name: K E Y Show all work on these pages. One sheet of notes permitted. Do not unstaple. Prbblem 1. A 120Vrms2 6QHZ wall outlet voltage powers a lossless DBR, which in turn supplies power to a laptop computer. The computer draws a constant 35W. Suppose that there is a sudden outage of AC voltage. The DBR capacitor continues to supply 35W to the computer, but when capacitor voltage Vdc falls to 100V, the computer shuts off. The elapsed time is known as ride-through capability. Assuming negligible voltage ripple on the capacitor, how many uF are needed to provide 15 seconds of ride-through capability? ‘ Z , z. m mam ~ ‘Lz:C(me;<- "WV/WM) W filo/e +ka 9PM!th _ a (390.9 .mm him—231.5003?“ EE362L, Fall 09, Test 1. Two Problems. Name: K Y Show all work on these pages. One sheet of notes permitted. Do not unstaple. Problem 1. A 120Vrms,‘60Hz wall outlet voltage powers a lossless DBR, which in turn supplies power to a laptopicomputer. The computer draws a constant 35W. Suppose that there is a sudden outage of AC voltage. The DBR capacitor continues to supply 35W to the computer, but when capacitor voltage Vdc falls to 80V, the computer shuts off. The elapsed time is known as ride-through capability. WW Assuming negligible voltage ripple on the capacitor, how many uF are needed to provide 15 seconds of ride-through capability? " KEY Problem 2. A common mistake is to assume that the negative terminal of the DC bus of a rectifier is at zero potential with respect to the building neutral. Consider a rectifier operated directly from a 120Vrms, 60Hz wall outlet. The load is resistive, and there is no DC capacitor. Analyze the rectifier circuit and determine the voltage waveform of point b with respect to point n. Explain your reasoning very clearly, and neatly sketch the Vbn waveform. { A . game. ,, ng‘fi hwy/meet; “Far swam, 99 Vbn) 3'” VW 3 v6 EE362L, Fall 09, Test 2, Oct. 14, 2009. Name: 2 One sheet of notes permitted. To receive full credit, you must show your work. . 50w m 'zsf-A” 5 0w a. 1in : 48V J 1L Iout 51— I 2v Hvé’ ’* r23 "4' Buck Converter 0.010 7': lQusee 40%? 2%”9 02W 75”“ A b nverter is operating in steady-state and converts 48Vdc to 12Vdc. The switching frequency is OOkH , and the load is 60W. L = IOuH, and C = lOOOuF. Assume that Vout has very low ripple. With regard to your graphs: Assume tlmlheMQSFEZF-wswit Wfifl"*'*¥omwndgax§§wf , so les should 9th include zero (,1. ogflfl L _‘L, -_; Z...) 2, ;: V "LE, ;, ’ 550/4920?» L 5g: -/2 «g W V ) / cw -6- z" i a. S etch onéicycle of the rig ct ‘ M which they occur. Compute the rms value of the current. The reason for this question is that . . 2 2 1 2 1nductors are rated in rms amperes. Use [ms 2 Ian,g +Elpeak_t0_peak . «w mmnmww... Wmmnmwww -— " ' ms. -c/ . , .. . .. ,, or (3,13%é2rl , ow1ng values for min and max currents and the t1mes at b. Sketch the diode current and use your sketch to determine its peak value. The reason for this ( question is that diodes are rated in peak amperes. 0. Assuming that Vout is constant, sketch the capacitor current and use your sketch to determine its (w peak-to-peak magnitude. The reason for this question is that capacitors are often rated in peak-to- : peak amperes. , (1. Use the graph from Part c. to graphically compute the peak—to-peak ripple voltage on the capacitor ( and express it in percent of Vout. The reason for this question is that it is desirable for the load voltage ripple to be less than 1%. ' W all“ W5 40% “my... Iain). M awning , "I? . .. , fififllflfllfififlfifig «mmmmmmwmufiummmmu .. .fiflflaflflflflflfififlflflfl i afllfiflflflfififlflfiflfil . I .. fififlfifi‘flflflflfl ., I V ,. ‘3‘ .Iflflfl flfi‘ ’ V . .fllflflflfllfigfiflfl . :; tin 12.41%? T), uttfi.iu5§§#fi .nxxuwfinnunxuxg. a mu; xxxaut m” .. . ,. . I’lfiflvmrfluni ., Eflflflfihfififlfla‘ a; EwinllflfifififlfifllflIfl-fi‘fl’ fl . l ,. fififl ‘Iflflfl. 3 w m I gflfiflfflq . .fififflflflhfl Efiflflflfllli *5, n «5..., “.Kfifliflflu . Ififlfififl .. *flflfifl“ an figflflflflfiflfifl‘ ,flflflfl Nfiflfififlflfln” . a. .‘ I. . U .figflflfi fig...” Nlflfififi, 3‘ an w . I. .. . . .. r, figflu E afflfifififlgflfifltig‘lfll lg 2, A 33’: 2995\(3MLM ' , , “Iaugtmw , £3323”;fitngxkuuuuxa urn. swung, firmgwnafitnullnnuéufi1h.”an _. y. M .. inguunnnnuutrukuuunfi nag gummy: figy‘wlflnuiunnunwm gaming .Auuunnngaxxuuuna a A ,. _ . V . V V H _ , _ _ V _ . . . .,-wmauuxnuixxmfl.awning, .. H H . . . . in tigexafi autnduaninmux . V q _ p ,, _ . . . unwaninxunuumaui‘xaifin , ._ z.vi«unnatnuuuninulgugfi Illigfifil 2 5 a LL 0 .g W 0. a \0 Am a o 0 ’50 EE362L, Test 3, Nov. 18, 2009. Name: i : Y I 0 ‘EOE Eli/“3) 75V Wallis ‘Wfie‘ (40‘) W 4mg 1. If you are operating with a Vcont connected to the LEFT input and ma = 1”, what w 11 happen if you simultaneously connect Vcont to the RIGHT input? (L-FIQ) becomé; Zvcoy+. 5‘0 744“ gum/0.5 +0 2’0, C/UF @flfl5 Mi? hem/<7 éflwtufl/thfl. 2. If a Vcont input signal is peaking at 1.5V, what gain multiplier do you need to hold ma as close to 1 as possible without exceeding 1? Regarding the PWM Control Circuit: ’\ “WV-Mink come. ea (55 ML 4% $0 34W boast" Wham/ac! Is .3}; :1. $35 ;@ 3. Why do we need two comparators instead of just one? t s, \t 72219 Camp/M I Was M) me, (it I/D, 0N er pr/MK; Van/w ‘lv V770 v 71¢ 0 H; m. (fierwiflmees -’ Vac/Vi“ +0 VTTQL 4. If 1.5nanoF results in a 120kHz triangle wave, how many nanoF will give you approximately a 10kHz triangle wave? J,. F; C; V O M: __———-—— :‘4 I“, ’ —/ I ’5‘ C C, ) 62 Cl@-«{/Q(/D 5. The output has VA and VB signals. If you View VA with respect to the PC board reference, with ma = 0, explain what you will see. Show the min/max values. 71MB W49 It" ch eckomt 9151;?! Z41 * D p0! $.40 VA with Repeat +79 ’IZV was. m o 90 wfth R€6p€c+ +32 0V l+ is ‘73“ O M Z w w I D :0/>p R yo 5 Oman ' E § «350.5 m com 46¢ 39mm .90»... 9:00,»... .cwu 03m: 395?.» ‘ . . J v: I 0N3. no . IIIIIIIIIIIIIII$HHHHW m3«m.m #m mmam E V580” .WWWW. m .35 “3.56 ucu nu 39m .wm .pom . . , . £328 thoo 23¢ .mwmmm 8? m S. 5 moom nN Honegoz coin; 2:26 8.55.0 .5202: 23m .moEoboo—m— $39M “Haemmm EE362L, Test 3, Nov. 18, 2009. Name: 2 Regarding the H-Bridge Circuit: 6. Explain why we need the 1500microF input capacitor. 7%,; CAP provides #46, “pl/(NGIAH Neecgé’oQ ha the load. The. \/ a, gap/Igwmng have, 7100 Muoli kegz’sfmm. 7. WEE tigpefpg': oggfiiso lfigffcaézififz’thfitfofi $263912. M kc Quesh‘zw 6/ ace/9+ til/:5 i ' 5W9 5+;WN9 The, [ Lyric Wfifi-‘i’ filial}? 10%?” 6? QMNQ‘Q O‘VU 7£L(/€/l/ 04/ qu‘ckvféz, 8. If both A+ and A- switches accidently close at the same time, and the lSOOmicroF input capacitor has 100V, and the parasitic inductance of the current path is 1microH, how long will it take for the A+ and A- MOSFET current to reach 30A burnout? 0’»? dj V. _,, MO... .54 , I m. 5‘? .4 ,, W‘ 1’; AAXSM... eeficixee 30A )‘A/ 9. and 10. The series output filter consists of 100 microH and a net 0.2 microF. If the H—bridge is producing 120Vac of 60Hz, and SOVac of 250kHz, how many amperes of 60Hz and 24th ZSDK'H‘Z current are flowing through the filter capacitors? \COV (o o I+1~ \ I 250 KH? z ‘1 0' 93 in” gan—(zww’Y/o‘t) :élSVJL 1 Igzfibow 2x 104’) fi _.L__..,——. , r I ngfiS’ODWWlXW) 3 ' fl ;., r/ ’ r .. “2:, I ’ iljéoi; Sign ' \I"? \4 So 25% " we m¥6§€MWWWWNWwwwmmwmmmmmmwwwmmmmWWMWMmmmmmmmm6T§§ugg駧Umwmwmér§§ufigggévmmmm + + w Bk 188k DD Five luF, 58V in series 1 @@u ,ESBU EE362L, Fall 89 H-Bridge Inverter Prof. Mack Grady Nov. 2, 2009 Fewer fram 12v PNM Centraller Mall Mart Terminalg U? S! C US Qua; 0—6 Gncé IMF VB 8589 VCC IBUF,[email protected] 18m?,[email protected] n,»12,3,~1a . Frcm PNN Controller ” E C:\Program Fi|es\ExpressPCB\H_Bridge_091102.pcb (Silkscreen, Top layer, Bottom layer) ...
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This note was uploaded on 04/03/2012 for the course EE 462 taught by Professor Grady during the Fall '11 term at University of Texas.

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EE362L_Fall09_Tests - KI: EE362L, Fall 09, Test 1. Two...

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