EE362L_Spring07_Test - EE362L Test 1 Feb 14 2007 Three equally-weighted problems Name Y Show all your work on the three test sheets A correct

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Unformatted text preview: EE362L, Test 1, Feb. 14, 2007. Three equally-weighted problems. Name: Y Show all your work on the three test sheets. A correct answer by itself, without supporting work, gets no " credit. Each problem is worth four points. One sheet of notes is permitted. Do not unstaple. Problem 1. Determine the rms value of the stairstep time-domain voltage waveform shown below; a 2_a 3 51 3 0 OzzzzT 424 Page 2 of 4 EE362L, Test 1, Feb. 14, 2007. Three equally-weighted problems. Name: Y Show all your work on the three test sheets. A correct answer by itself, without supporting work, gets no credit. Each problem is worth four points. One sheet of notes is permitted. Do not unstaple. Problem 2. An automobile is inside the box shown below, and the box has two wires connected to the “outside world.” The volta e agd current waveforms for the wires are 100 0 a? vim" ‘ ' v(t) = 100 sin(a)t + 10°) + 20 saga); — 100°) Volts (W 5%) + ‘ v(t) i(t)—> i(t) = 2sin(a)t — 20°) + 4sin(3a)t + 40°) + 3 sin(5a)t) Amperes Zézo“ awn“ 310” Use the power expression for Fourier series to determine the average power Pm,g that flows into the box from the outside world. 0’ 91 15> ‘ My _ avg. 3’ ygs‘ Jim. 4'“ ZVKRW$$K 9k.) KW \ : Ji ‘00.; Lac,(yo°—-(-u§)+ 20'4’1044001‘4Q] w i 00 C0 430‘”) +~ W W (44’0") :- QM wane ==~ 5’6 W Page 3 of 4 EE362L, Test 1, Feb. 14, 2007. Three equally-weighted problems. Name: é I Show all your work on the three test sheets. A correct answer by itself, without supporting work, gets no credit. Each problem is worth four points. One sheet of notes is permitted. Do not unstaple. Problem 3. The FFT of the ENS wall outlet .9 . ge is shown. The horizontal “span” is lkHz, and the “center fre ” ' 500H The vert'cal scal is lOdB r d'vision.‘ \ .y- , > ‘, Note —make sure that you show adequate marks and values on the figure to justify your answers. a) Which two harmonics (above the fundamental) are the largest? b) Estimate the magnitudes of each of those harmonics — express your answers in percent of the fundamental. c) Use the results of part b) to estimate the total harmonic distortion (THD) of the ENS wall outlet voltage. a) Silva 23: 7% V) 5'31 Lemma. {"7 36 dawn) 'Ffitim Hm... . p ‘1», mi Lama/lama. is» 4'0 din clam; WW, “W i. V db V : IDdblza (“0 1220103”, 3 5' bani? V3... } 3L, ' ’36 96» infirm 0.052 @158?“ W“WMMM \o) 934%“li ' ’ «NM/“pm r f1?” EE362L, Tes@ Mar. 28, 2007. Four equally—weighted problems. Name: K p Z Show all you ork on the test sheets. A correct answer by itself, without supporting work, gets no credit. Each problem is worth five oints. One sheet of notes is permitted. Do not unstaple. Problem 1. A DBR is plugged into a 60Hz wall output and is operating in steady state. The AC current has triangular pulses, is half-wave symmetric, varies between iSA, and has zero average value. The average voltage on the capacitor is 160V. C is very large and has very low ripple voltage. The load power is constant. Determine the average power delivered to~the load. Explain your reasoning. Hint: use the DC side. + “'5 lei; «a P Constant power load Puléés Nae, Fagfiim, iac Amperes 1/60 Hz = 16.67 msec “£7 Ila 6%(5V’ 9“") +‘lmasa Au. All Wit—w \oecwse *wlme {Q CffiNfiflfi'fiNW‘ ‘3; WW M) d; Zn 2,. M) Page 2 of 5 EE3 62L, TesMar. 28, 2007. Four equally-weighted problems. Name: ” ‘1~ 7 Show all you I ork on the test sheets. A correct answer by itself, without supporting work, gets no credit. “ Each problem is worth five points. One sheet of notes is permitted. Do not unstaple. Problem 2. Measured solar radiation data, sun zenith angles, and incidence angles for our fixed panels for Feb. 16 are shown in the table. A. Estimate the incident power (per square meter of surface area) on our panels at Use A ¢ 5 m i (fix/H-131) (Bali {9&7 2 Pincident = DH + W ' Cos<flincident> W/ m COS sun mafil B. Repeat part A, but assume that the panels are unbolted and then directed toward the sun so that the incident power is l'naXirnized. , Mama. E :2. 0) Feb. 16 Global Diffuse Zenith Incidence Horizontal Horizonta Angle Angle Time W/m2 W/m2 de rees de rees I mm mm Using 45" tilt, 190° azimuth l i .es “ -a (pa + Water, _. mew/M1 We GW-fi r A mm m ,, llama» a. H» W ’ vu-MIHWMWmvp-mmrvmww~3bw~wmwr¢vmw‘--v “mm/MW van-«matum W "mm-4W Oié‘l’fi’ m ................ WWWMWW”MNMW W W “W wwww ,, x . n m 1,7 I , l l. «a A pom-l6 sail ‘ 57 + E40-3'l .0,33¢i:3%w/M2 «M A» X E), 0.5!; fl , \K H H . i t: Clé’pwclrw 5W ' l, [\59W/1 Page 3 of 5 $5? + 67;" 60 oOfiM 3:7? fiqOW/j’ha n n. , r: l0li9 W/M " 33' .. EE362L, [email protected] 28, 2007. Four equally-weighted problems. Name: K \g “/‘Y Show all your work on the test sheets. A correct answer by itself, without supportin work, gets no credit. ‘ Each problem is worth five points. One sheet of notes is permitted. Do not unstaple. Problem 3. The I-V curve for one of our solar panel pairs at one particular sun/sky/orientation condition is given below. 6.0 23 ===EIQIIIIII 45 III-l-E!-I-I 40 --------!--I J A M5 III-IIII-s-I Hfi an III-I-I-INI- %9/ :25 III-Innunnuqr 20 III-III-I-Ifl .5 III-I-I-lmfim .0 Innlgaii-Inm i\ 05 EEiIIII-I-Ifll 0.0 3393/: 7 A 2051. V - volts 36. 5/ .y. “Mm. "MM A. If a 209 load resistor is connected diva“) the panel air: how muclTpo will the resistor absorb? Hint: use a load line for the > :5 é WM... B. If a boost converter is connected betweenfitlfé‘p‘anelpa‘ir'and’tfiloadfifesi‘stor, what duty cycle D will cause the panel pair voltage to drop to 24V? Hint: the equivalent resistance at the input of the boost converter is Requiv = Rload . (1 — D)2 ' Razélfijv W .561... a , "54*!" X . 0 i 2 3, :fi ,2 a (1 V) “* a 4’ H) W mm 1“ 0.4616) M 7 "x .510. m “ Mg“... m. . _ 3 hwwwflnwwwm... Page 4 of 5 .ri’W EE3 62L, Tes@}Mm. 28, 2007. Four equally-weighted problems. Name: l 17 Show all your work on the test sheets. A correct answer by itself, without supporting work, gets no credit. ' Each problem is worth five points. One sheet of notes is permitted. Do not unstaple. Problem 3. The I-V curve for one of our solar panel pairs at one particular sun/sky/orientation condition is given below. PV Station, Bright Sun _ I”? a . QJW) Mill (L 9 4 SE EEEEI-Ill-IIII 5D ————=!-!-IIIII 45 III-I-Ihfl!--II 4D III-IIIIIhu-I- M5 III-Inl-Iuns-I Ho III-I-II-IINI- h5 III-IIII-I-Iu- 20 III-I-II-I-III .5 III-II-IIIIIIH V,1l 1D III-IIIIIIIIIM-wtflg’ 05 gig-Ingaaaafimmn m on ufiIi-I-II-I-Iflfl O 2 4 6 8 1012141618 20 22 24 26 28 30 32 34 36!}; 38 4O "'“°"‘°' 3mm“l 0.61544- A. If a 40!) load resistor is connectedflglingqtjxgfio.thepanelpair:howm‘uchupgwer will the resistor absorb? Hint: use a load line for the resistOr “Xi? Y f:- W B. If a boost converter is connec ed betweenthepanelpair‘andwthealoadresist , what duty cycle D will cause the panel pair voltage to drop tO‘Z'ZW? Hint: the equivalent resistance at the input of the boost converter is Requiv = Rload ° (1 _ D)2 ' 0'0)?“ 2 (24% ON I ll 2 ‘”' (9'12. .- M v (Q LDAD 4' '“ mm.“ “mum.-. ..w....,.....m»~ Page 4 of 5 i \ I » EE362L, Test£2c, ar. 28, 2007. Four equally-weighted problems. Name: K E )7 Show all you ’“rk on the test sheets. A correct answer by itself, without supporting work, gets no credit. Each problem is worth five points. One sheet of notes is permitted. Do not unstaple. Problem 3. The I-V curve for one of our solar panel pairs at one particular sun/sky/orientation condition is given below. III-III... is: III-I-I-I-I-I III-I-I-I-I- 0 2 4 6 810121416182022242628303234363840 V-volts 33.5V) 33 A“ A. If a 109 load resistor is connected directly to the panel pair, how much power will the resistor absorb? Hint: use a load line for the resistor. P :R (3a 5577/ 0 z: I I Z W B. If a boost converter is connected between the panel pair and the load resistor, what duty cycle D will cause the panel pair voltage to drop to 24V? Hint: the equivalent resistance at the input of the boost converter is Requiv = Rload ° (1 " D)2' (me2 W? Page 4 of 5 EE3 62L, Tesar. 28, 2007. Four equally-weighted problems. Name: K 2 (p l (I Show all you work on the test sheets. A correct answer by itself, without supporting work, gets no credit. ‘ Each problem is worth five points. One sheet of notes is permitted. Do not unstaple. Problem 3. The I-V curve for one of our solar panel pairs at one particular sun/sky/orientation condition is given below. 50 - 11:. 4:5 ‘35-” a 4.0 - I _/.~“)‘SV w 35 I 3 I g 30 .I......... 3. Pr MM” A _' 2.5 0 2 4 6 810121416182022242628303234363840 V-volts A. If an 89 load resistor is connecte 1rectly to the pan’e'l'pair,“'h’dW‘ffiuchpewergwill the resistor absorb? Hint: use a load line for the resistor. F v; S V) (3 5:? 192:, l 2 “mt—“w.” a» _ B. If a boost converter is connected between the panel pair and the what duty cycle D will cause the panel pair voltage to drop to 24V? Hint: the equivalent resistance at the input of the boost converter is Requiv = Rload ° (1 _ D)2 ' “I? 3 (f3 J3) 2.... f H) O .‘7‘? 9'” Page 4 of 5 Show all your work on the test sheets. A correct answer by itself, without supporting work, gets no credit. : Each problem is worth five points. One sheet of notes is permitted. Do not unstaple. 131336214, Teséa/[ar- 28, 2007. Four equally-weighted problems. Name: I (z, I '7 Problem 4. Much can be learned from the inductor current of a DC-DC converter. Consider the current waveform for a boost converter inductor L, as shown below. . L stoin Closch 45—1” \1 3W EE362L, Test 3a,. April 25, 2007. Four equally-weighted problems. Name: K S Show all your work on the test sheets. A correct answer by itself, without supporting work, gets no credit. Each problem is worth five points. One sheet of notes is permitted. Do not unstaple. Problem 1. The output filter of your inverter is shown below. Assume that the voltage on the inverter side has a 10Vrms, 40kHz component. How many rms volts of 40kHz appear across the 10 “F output capacitor? Note — no load is attached. lOOuH Au + vw+ N Inverter F Output side V . 10M . . . 3N1 Side | (no load 1s attached 1n this problem) .I N. IMpeo/AA/Le. (JINW'Q/(A) ‘3- W , V3,, a + 9: — MI I 6 JW' d(WL'W¢) 4‘15» -.-,- wc _. wl _, I VIM erzuL’C fl wZLC-d ’ l~wZLC /~— [ZWX40000)2(lOOXlD'6)(10)“ng : ’ :eQOlém 1~éaz Vow :‘ V35»! Xéo'mbm> it- iovfiwry Check QSJSL .: 03‘??? :3: ~30. 0 role/M . u — ,m: m (a gut-00”” a "01,4"7 f} ..................................... WWWWWWWWWW WWW 2 W W 50m 00 I024 Vm / EE362L, Test 3a, April 25, 2007. Four equally-weighted problems. Name: K \ Show all your work on the test sheets. A correct answer by itself, without supporting work, gets no credit. ‘ Each problem is worth five points. One sheet of notes is permitted. Do not unstaple. Problem 2. The figure shown below is taken from the lab document. The approx. 2 us time between the two vertical bars is the delay time between the moment that the 12V driver output “goes high” and the actual “turn on” of the MOSFET (which occurs when VGS z 4V). The MOSFET gate capacitance C is a few nC, and the series gate firing resistor R is 12000. Suppose you want to double the Zus delay time to add more blanking. Estimate the new series gate firing resistance needed to do this. Hint —— in the early portion of the VGS rising curve, its slope is Vfinal 12 = —-— Volts per second. Give good reasons for your answer! 1 RC actual MOSFET turn on ,. , ~ " Pag'63 ofs L. I 00 Z” w 6052“ EE362L, Test 3a, April 25, 2007. Four equally-weighted problems. Name: EE- 1 Show all your work on the test sheets. A correct answer by itself, without supportlng work, gets no credit; Each problem is worth five points. One sheet of notes is permitted. Do not unstaple. Problem 3. Your PWM circuit uses a 24V supply, a series resistor, and a comparator to operate two daisy- chained'optoisolators for the A+, A— firing circuits. ' PWM Control Circuit VF - LED forward Voltage Suppose that you daisy chain five optisolators (instead of two) in series, with each one operating at the circled point shown on the curve (1.6V LED voltage, 15mA LED current). What value of series resistance (in ohms) is needed to do this? , (—7 ’5 714 :4 a +; I (94v K: 24~ (I.e)(4)__ war; 0,0/5" ” 0.0/5 " elk (was, R: (Rat-«(@ff), gal—«7,5, (QIO/Sw M M 0%” vaM/mw) £00m Ofioe/ Page 4 of 5 EE362L, Test 3a, April 25, 2007. Four equally-weighted problems. Name: K E 2 Show all your work on the test sheets. A correct answer by itself, without supporting work, gets no credit. ' Each problem is worth five points. One sheet of notes is permitted. Do not unstaple. Problem 4. Show me how familiar you are with H-bridge connections. Use your pencil to neatly “Wire up” only the requested portions of the H-bridge. Leave out the fuses. The requested portions are 0 Draw in the input filter capacitor. 0 Draw in the output filter inductor and capacitor. 0 Draw in all the l6—gauge (or l4-gauge) wires that are attached to the A+ and A" terminal blocks. ' Show the terminations of both ends of these wires. When wires cross, make it clear if connections are made at the crossings or not. Do not use colors. If you need to re-draw, use the duplicate figure at the bottom of the page, and then cross out the top figure. IAIN6L I H “'Bfliciccja wwmacrf'iws 4m A" 35an g5. green/M Duplicate figure, if needed EE362L Final Exam, May 10, 2007, Name: Z , Page 1 of 10 10 multiple choice questions. Four 8.5xl 1” note sheets permitted (both sides). No laptop computers. Show all work on these pages. You must show sufficient reasoning, equations, and steps to justify your answer. Circle the correct answer. If you believe that the correct answer is not among them, then choose “Other” and write in your answer. No partial credit. Do not unstaple. Problem 1. A variable resistor is connected to the output of an ideal DC-DC boost converter. Vin = 40V, Vout = 100V, f = SOkHz, L = lOOuH. Vin and Vout are held constant. The variable resistor ohm value is initially low enough that the converter is operating in continuous conduction. Slowly the load resistor ohms are increased until the converter reaches the continuous/discontinuous boundary. At what resistance does this occur? (10 accuracy) 9 “'5’ “‘7’ out , .L... z W + V+ w in}; ) ij Ou+ V. out wwwwwwwwwwwww _ MW... in W ‘ fl . w ‘ ‘ - (t—n fik .. flew 424/ (Egg If] M Hm EWING/412g all“: wwmmg/dflac Wampum, (Harem )1” lactkfi like A” ZIW:(Y%Q>(DT> . v 1m: VENLDT ; 204A S0 IOULT 2 (lab): N z 0.41;; 0,76% Eiwwn R " it?» W illfiifil F va-vn-mww--..—.mmmm..wwwnm mm... .../..M...-.-«m Ck“ k" PIN : VIN “T'in :i (40) (2‘4) :3 (A) Post-t YT ”‘ (“9052' 9600 EE362L Final Exam, May 10, 2007, ' Page 2 of 10 km ~ Problem 2. The periodic voltage waveform shown is applied across a 100 resistor. The period of the waveform is T seconds. For the first period, v(t) = t2 , and the waveform keeps repeating. If the average power to the resistor is 100W, determine T (in seconds). (0.1 second accuracy) 2 T v(t) = t 2 ‘ ‘ Z \ vm :- 737) am» 0 0 T 2T 3T EE362L Final Exam, May 10, 2007, ‘4‘: Y Page 3 of 10 Problem 3. The series circuit shown has been operating in stead -statemfwomr’_amlg_n~ time. v(t) =12(sin1000t+ 2) volts, R = 100, L = lOmH, C = lOOpF. A DC voltmeter is connected across the capacitor with the polarity shown. What voltage will the meter read? (0.1 volt accuracy) I A 5MV€I< pearl-{ow rko b {4M + - ., , \ ‘ Va) w w Wk 1000 Ami/96¢ C" m «+1»! AN cl —15.0 volts 12.0 volts I 15.0 volts Other ‘ n lg 7716, Flvefifije. Will/(€15 Come «fi'fiom ‘on, DC H _._/ ‘ . n V w (3 J . {Mm outta/$0 “New C "5 Open «W NO (“WWW HOW?" REV/0 yl 1‘5 4- 5404+ C)”, ;;\/ Tér’C IS AN p/mu 54:31, [ WWW We, QN‘IL‘llfle, (24V affirm/29 M19049 (.1 26M m macs-4;; W?“ 1,14% EE362L Final Exam, May 10, 2007, K E Y Page 4 of 10 Problem 4. A bridge rectifier module is used to charge a battery. Starting from zero, Vp is very slowly increased with a variac until the “fast-blow” fuse blows. At what Vp does this occur? (assume that the fuse blows instantaneously when 5A is reached) (0.1 volt accuracy) 0.20 H . 13.6 volt battery 0.30 + VP sin(1207zt) volts / 0| 3% $7)” 0’ Burma ch Clue/lion the, cjerwllg is EE362L Final Exam, May 10, 2007, Page 5 of 10 Problem 5. A 16,000pF capacitor is charged to 40V. At t = 0, the switch closes, connecting the capacitor to a 5000 resistor. How long does it take for the capacitor to give up 2/3 of its stored energy? (0.1 second accuracy) 9““ EE362L Final Exam, May \10, 2007, K Page 6 of 10 Problem 6. Consider the inverter that you built. Assume that you are powering its MOSFET driver chips with 18Vdc instead of 12Vdc. MOSFET tum—on occurs when VGS = 4V, and you need a turn-on‘delay of 2 usec to achieve adequate blanking. The capacitance of the MOSFET gate is ' 5(10‘9) What value of turn-on series resistance should you use in the output of your driver chips? (three digit accuracy) I! v {a rig/r {J wr(+>:-IY(I—-e law-L m —2sec~ 1;,WM ................. zzm:j— C: 4% 7? [3(fl’ a #4E*") 251561 i :=« ( v 6 7; /% 49 '2‘, ID V _ (in Ww e "’z/éaf’cm'o) = 4 / EE362L Final Exam, May 10, 2007, K E. Y Page 7 of 10 Problem 7. The time—domain waveform and FFT of the wall outlet current drawn by a PC are shown. The vertical scale is lOdB per division. If the fundamental current (i.e., 60Hz current) is lArms, what is the rms magnitude of the 11th harmonic? (0.01A accuracy) I l/Wltmoufc '; (VD) hm ~ ‘ _ . ‘ EE362L Final Exam, May 10, 2007, Y Page 8 of 10 Problem 8. Assume that the inverter you built is operated as follows: The DC input voltage to the H-Bridge is 20Vdc The peak value of the 25kHz triangle wave generator chip is 4V You connect a pure 500Hz sinusoidal voltage to the Vcont jack. The peak value is adjustable. Your 5000 Vcont potentionmeter is set to the maximum Your inverter output drives a single high-power 8!) speaker The output of your inverter is a low-distortion SOOHZ sinewave The output filter has no affect on the 500Hz signal What peak value of Vcont will result in 10W average power to the speaker? (0.1 volt accuracy) EE362L Final Exam, May 10, 2007, K E Y Page 9 of 10 Problem 9. An ideal DC-DC buck converter interfaces one of our solar panel pairs to a car battery. The Thevenin equivalent circuit of the battery is shown. Your objective is to charge the battery while holding the solar panels at their maximum power point. At what duty cycle D must the buck converter operate to achieve this? (0.01 accuracy) 0.20 HJF 13.6 volts Cr [4 fink Thevenin equiv. of battery ‘ (0 K Max power point is 28V, 4.6A l l ll‘i‘ 1 ll) .48 I P2044 Jr‘lm bfi‘Hfleéf sin/e) we Me. a"); @Zsz, J» m ' m, VP 9 -— 0,21 751—435 «mo 1’ f w) V993— 0,;er law 2: 0 3'va DZ __ W 3?; WWW w Vp * DZ _, Lag!) _, 02:31? 5.0 Dzw0fl$6 D”0;OSQ¢1 ’5 O D : 0,42% It (0,°r$f)1-4r{i)(—0,0§2i) D: 05%)7Qm “:4 Z, Wm ________ W W MMMMMM - m, M -.— M EE362L Final Exam, May 10, 2007, - K E Y Page 10 of 10 Problem 10. The incident power curve for our panels on April 25, 2007 is shown below. Use the curve, and assume a panel efficiency of 14%, to estimate the kWh of electric energy per square meter that one of our solar panel pairs could have produced on that day if it was max-power loaded. (0.1 kWH/m2 accuracy) Wlm2 15 16 17 18 19 gmt‘ to Oak, 15 (ppwht maiden—#- ...
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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 at Austin.

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EE362L_Spring07_Test - EE362L Test 1 Feb 14 2007 Three equally-weighted problems Name Y Show all your work on the three test sheets A correct

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