Hi guys, So I signed up for this power electronics course that Klaus linked to a week or so ago. (from coursera and CU). I wanted to check my homework so I made an LTspice file. (I?ve changed it a bit so as not to give HW answer.)
I?ve got a question. If you look at the simulation there is this rather l arge turn on transient. Transient has a period of ~1.3 mS (~770 Hz) and a Q of maybe 4 or 5. If I put in my LCR numbers (100uH, 100uF, 8 ohms) I get a frequency of ~1.6 kHz and a Q R/(omega *L) of 8. So the numbers are close... but a bit off.
So is this transient behavior important... or when you build a real one doe s the controller take care of it by changing the duty cycle? (To get a better guesstimate of the transient behavior I might ?guess? that the inductor counts a bit more here.. like maybe 2*L 'cause it?s on all the time.)
Thanks, George H.
LT spice
Version 4 SHEET 1 880 1108 WIRE -112 96 -272 96 WIRE 0 96 -32 96 WIRE 144 96 0 96 WIRE 272 144 64 144 WIRE 368 144 272 144 WIRE 272 176 272 144 WIRE 368 176 368 144 WIRE -128 224 -160 224 WIRE 0 224 0 96 WIRE 0 224 -48 224 WIRE 64 224 64 144 WIRE 144 224 144 96 WIRE -272 256 -272 96 WIRE -272 272 -272 256 WIRE -160 272 -160 224 WIRE 272 288 272 240 WIRE 368 288 368 256 WIRE 368 288 272 288 WIRE -64 304 -64 272 WIRE 80 304 80 272 WIRE 368 336 368 288 WIRE -272 384 -272 352 WIRE -112 448 -112 272 WIRE 128 448 128 272 WIRE 128 448 -112 448 WIRE -112 480 -112 448 WIRE -112 592 -112 560 FLAG -272 256 +V FLAG -272 384 0 FLAG -64 304 0 FLAG 80 304 0 FLAG -112 592 0 FLAG 368 336 0 FLAG -160 272 0 SYMBOL voltage -272 256 R0 WINDOW 123 0 0 Left 2 WINDOW 39 24 124 Left 2 SYMATTR SpiceLine Rser=10m SYMATTR InstName V1 SYMATTR Value 15 SYMBOL sw 160 224 M270 WINDOW 3 -80 -1 Left 2 SYMATTR Value MYSW SYMATTR InstName S1 SYMBOL sw -32 224 M270 SYMATTR InstName S2 SYMATTR Value MYSW SYMBOL voltage -112 464 R0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V3 SYMATTR Value PULSE(-5 5 0 1u 1u 9u 20u) SYMBOL res 352 160 R0 SYMATTR InstName R1 SYMATTR Value 8 SYMBOL ind -128 112 R270 WINDOW 0 32 56 VTop 2 WINDOW 3 5 56 VBottom 2 SYMATTR InstName L1 SYMATTR Value 100µ SYMBOL cap 256 176 R0 SYMATTR InstName C2 SYMATTR Value 100µ TEXT -760 536 Left 2 !.tran 0 10m 0m 100n startup TEXT -816 488 Left 2 !.model MYSW SW(Ron=0.01 Roff=10Meg Vt=0.0) TEXT 232 424 Left 2 ;Boost\nGH 10/2013