Version 4.1 SHEET 1 2388 1232 WIRE 384 -368 352 -368 WIRE 496 -368 464 -368 WIRE 688 -368 560 -368 WIRE -768 -352 -800 -352 WIRE -496 -352 -768 -352 WIRE -368 -352 -416 -352 WIRE -240 -352 -368 -352 WIRE -160 -352 -240 -352 WIRE 80 -352 -160 -352 WIRE 80 -336 80 -352 WIRE -800 -288 -800 -352 WIRE -368 -288 -368 -352 WIRE -240 -288 -240 -352 WIRE 80 -224 80 -256 WIRE 144 -224 144 -256 WIRE 144 -224 80 -224 WIRE 192 -224 144 -224 WIRE 352 -224 352 -368 WIRE 352 -224 272 -224 WIRE 400 -224 352 -224 WIRE 1376 -224 992 -224 WIRE 688 -208 688 -368 WIRE 688 -208 576 -208 WIRE 736 -208 688 -208 WIRE 80 -176 80 -224 WIRE 1616 -160 1568 -160 WIRE 1744 -160 1616 -160 WIRE 576 -144 576 -208 WIRE 992 -144 992 -224 WIRE 400 -128 352 -128 WIRE 1568 -128 1568 -160 WIRE 352 -96 352 -128 WIRE -800 -16 -800 -208 WIRE -512 -16 -800 -16 WIRE -368 -16 -368 -224 WIRE -368 -16 -512 -16 WIRE -240 -16 -240 -208 WIRE -240 -16 -368 -16 WIRE 80 16 80 -96 WIRE 352 16 352 -16 WIRE 352 16 80 16 WIRE 576 16 576 -64 WIRE 576 16 352 16 WIRE 848 16 576 16 WIRE 992 16 992 -64 WIRE 992 16 848 16 WIRE 1568 16 1568 -48 WIRE -512 32 -512 -16 WIRE 848 32 848 16 WIRE 336 368 304 368 WIRE 448 368 416 368 WIRE 640 368 512 368 WIRE -768 384 -800 384 WIRE -672 384 -768 384 WIRE -448 384 -592 384 WIRE -352 384 -448 384 WIRE -224 384 -352 384 WIRE -208 384 -224 384 WIRE 32 384 -208 384 WIRE 32 400 32 384 WIRE -800 448 -800 384 WIRE -448 448 -448 384 WIRE -224 448 -224 384 WIRE -352 464 -352 384 WIRE 1360 464 944 464 WIRE 32 512 32 480 WIRE 96 512 96 480 WIRE 96 512 32 512 WIRE 144 512 96 512 WIRE 304 512 304 368 WIRE 304 512 224 512 WIRE 352 512 304 512 WIRE 944 512 944 464 WIRE 640 528 640 368 WIRE 640 528 528 528 WIRE 688 528 640 528 WIRE 1552 544 1504 544 WIRE 1680 544 1552 544 WIRE 32 560 32 512 WIRE 1504 576 1504 544 WIRE 528 592 528 528 WIRE -352 608 -352 544 WIRE 352 608 304 608 WIRE 304 640 304 608 WIRE -800 720 -800 528 WIRE -560 720 -800 720 WIRE -448 720 -448 512 WIRE -448 720 -560 720 WIRE -352 720 -352 672 WIRE -352 720 -448 720 WIRE -224 720 -224 528 WIRE -224 720 -352 720 WIRE 1504 720 1504 656 WIRE -560 752 -560 720 WIRE 32 752 32 640 WIRE 304 752 304 720 WIRE 304 752 32 752 WIRE 528 752 528 672 WIRE 528 752 304 752 WIRE 864 752 528 752 WIRE 944 752 944 592 WIRE 944 752 864 752 WIRE 864 768 864 752 FLAG -160 -352 power_supply_out_dev FLAG 848 32 0 FLAG -512 32 0 FLAG -768 -352 Vin FLAG 736 -208 error_dev FLAG 1376 -224 power_trafo_pri_dev FLAG 144 -256 pot_divided_dev FLAG 400 -224 inv FLAG 400 -128 non_inv FLAG -208 384 power_supply_out-1 FLAG 864 768 0 FLAG -560 752 0 FLAG -768 384 Vin-1 FLAG 688 528 error-1 FLAG 96 480 pot_divided-1 FLAG 352 512 inv-1 FLAG 352 608 non_inv-1 FLAG 1616 -160 power_trafo_sec_dev FLAG 1568 16 0 FLAG 1360 464 power_trafo_pri-1 FLAG 1552 544 power_trafo_sec-improved FLAG 1504 720 0 SYMBOL ind -400 -368 R90 WINDOW 0 5 56 VBottom 2 WINDOW 3 32 56 VTop 2 WINDOW 39 60 56 VTop 2 SYMATTR InstName L1 SYMATTR Value 100µ SYMATTR SpiceLine Rser=1m SYMBOL cap -384 -288 R0 WINDOW 39 -24 82 Left 2 SYMATTR SpiceLine Rser=20m SYMATTR InstName C1 SYMATTR Value 100µ SYMBOL res -256 -304 R0 SYMATTR InstName R1 SYMATTR Value 10R SYMBOL res 96 -352 M0 SYMATTR InstName R3 SYMATTR Value 9.5k SYMBOL res 96 -192 M0 SYMATTR InstName R4 SYMATTR Value 2.5k SYMBOL res 176 -240 M90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R5 SYMATTR Value 2k SYMBOL cap 496 -384 M90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C3 SYMATTR Value 100n SYMBOL res 368 -384 M90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R6 SYMATTR Value 2k SYMBOL voltage -800 -304 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V2 SYMATTR Value ac 1. SYMBOL bv 992 -160 M0 WINDOW 3 -90 113 Left 2 SYMATTR Value V=8.2*V(error_dev) SYMATTR InstName B1 SYMBOL bv 576 -160 M0 WINDOW 3 -195 111 Left 2 SYMATTR Value V=1E6*(V(non_inv)-V(inv)) SYMATTR InstName B2 SYMBOL res 368 -112 M0 SYMATTR InstName R7 SYMATTR Value 1m SYMBOL ind -576 368 R90 WINDOW 0 5 56 VBottom 2 WINDOW 3 32 56 VTop 2 WINDOW 39 60 56 VTop 2 SYMATTR InstName L2 SYMATTR Value 100µ SYMATTR SpiceLine Rser=1m SYMBOL cap -464 448 R0 WINDOW 39 -33 82 Left 2 SYMATTR SpiceLine Rser=20m SYMATTR InstName C2 SYMATTR Value 100µ SYMBOL res -240 432 R0 SYMATTR InstName R2 SYMATTR Value 10R SYMBOL res 48 384 M0 SYMATTR InstName R8 SYMATTR Value 9.5k SYMBOL res 48 544 M0 SYMATTR InstName R9 SYMATTR Value 2.5k SYMBOL res 128 496 M90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R10 SYMATTR Value 2k SYMBOL cap 448 352 M90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C4 SYMATTR Value 47n SYMBOL res 320 352 M90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R11 SYMATTR Value 4k SYMBOL voltage -800 432 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V1 SYMATTR Value ac 1. SYMBOL bv 944 496 M0 WINDOW 3 -90 113 Left 2 SYMATTR Value V=8.2*V(error-1) SYMATTR InstName B3 SYMBOL bv 528 576 M0 WINDOW 3 -195 111 Left 2 SYMATTR Value V=1E6*(V(non_inv-1)-V(inv-1)) SYMATTR InstName B4 SYMBOL res 320 624 M0 SYMATTR InstName R12 SYMATTR Value 1m SYMBOL bv 1568 -144 M0 WINDOW 3 -90 113 Left 2 SYMATTR Value V=0.6666*V(power_trafo_pri_dev) SYMATTR InstName B5 SYMBOL cap -368 608 R0 SYMATTR InstName C5 SYMATTR Value 330µ SYMBOL res -368 448 R0 SYMATTR InstName R13 SYMATTR Value 1R SYMBOL bv 1504 560 M0 WINDOW 3 -90 113 Left 2 SYMATTR Value V=0.6666*V(power_trafo_pri-1) SYMATTR InstName B6 TEXT 1280 -440 Right 2 ;this voltage gain of 24.5/3=8.2 is from\nhalf the input voltage divided by\nthe peak to peak sawtooth Voltage\nwe take half the input voltage as a half bridge\nonly puts half the input voltage\nacross the power tranformer primary. TEXT -344 -1376 Left 5 ;UC2526 half bridge, control loop response. TEXT -1024 976 Left 2 !.ac dec 100 10 100k TEXT 376 -1216 Left 2 ;firstly we have to add realistic ESR to the output capacitors, I have put this in as 20 m Ohms.\nthen running this sim as is shows two problems.\nthe peak in the response of the LC filter which could cause ringing or oscillations at 750hz\nrequires to be damped.\nthe loop does not have enough bandwidth, this will make the power supply respond slowly to transients, \nso the resulting output voltage transients will be larger and last longer. \nfor the damping \n...in parrallel with the output capacitor, add a larger capacitor with a resistor in series\nthe convention is to add 3 times the present value of C, \nthe additional R in series is the impedance of the inductor at the 750hz resonant freq, this is 0.22R\nadding this has removed the peaky response of the LC filter.\nin order to increase the bandwidth of the control loop increase the output R and C impedances by a factor of 10\n \nNow check that hte control loop is stable, so that it won't oscillate or ring.\nthat is check what the phase is when the gain goes through 0db, this is called the phase margin, this should be at least 25 degrees.\nif the phase goes through zero then check how much below 0dbs the gain is at this point, this is called the phase margin.\nfor this example the phase margin is about 26 degrees, you would not want it to be any less than this.\nthere is no gain margin as the phase does not go through 0 degrees. TEXT -688 -488 Left 4 ;LC filter and load TEXT -64 -496 Left 4 ;potential divider and error amp TEXT 840 -568 Left 4 ;supply volts\n/p-p sawtooth Volts TEXT -88 -608 Left 5 ;Development control loop TEXT -104 160 Left 5 ;Improved control loop TEXT -672 248 Left 4 ;LC filter and load TEXT -8 232 Left 4 ;potential divider and error amp TEXT 872 192 Left 4 ;supply volts\n/p-p sawtooth Volts TEXT 1272 320 Right 2 ;this voltage gain of 5 is from\nthe input voltage divided by\nthe peak to peak sawtooth Voltage TEXT -680 -1144 Left 2 ;click on run\nclick on "power_trafo_sec_dev".\nclick on "power_trafo_sec-improved". TEXT -696 -1200 Left 4 ;Instructions TEXT 376 -1264 Left 4 ;Calculations LINE Normal 528 -304 528 -304 2 LINE Normal 480 432 480 432 2 RECTANGLE Normal -144 80 -688 -464 3 RECTANGLE Normal 720 80 0 -464 3 RECTANGLE Normal 1344 64 832 -464 3 RECTANGLE Normal -144 800 -720 272 3 RECTANGLE Normal 672 800 -32 256 3 RECTANGLE Normal 1344 800 800 256 3 RECTANGLE Normal 1760 96 -880 -608 1 RECTANGLE Normal 1760 864 -880 160 1