Rp p1 p2 001 lpm p2 d 20u lp p2 d 4m ls 0 s1 1m k lp

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Unformatted text preview: nction to Vin+NVout Current ramps down in Lm ΔI = -NVyΔt/Ll Lm rings with Cd Flyback Phase 4: Off (DCM),Commutation (CCM) Phase 4: Off/Commutation Diode clamps junction to Vin+NVout Vin+NVout across Ll Current ramps up in Ll ΔI = (Vin+NVout)Δt/Ll Secondary current ramps downn by same amount Flyback SPICE Waveforms Zoom of Commutation Phase I(Dls) 33A -i(s1) I(Lpl) 27A 21A 15A 9A 3A -3A I(Lpm) 16.2A 16.0A 15.8A 15.6A 15.4A 15.2A 15.0A 14.8A V(d) 500V 450V 400V 350V 300V 250V 200V 150V 100V 50V 0V 100V 80V 60V 40V 20V 0V -20V -40V -60V -80V -100V 11.900µs V(s1) 11.925µs 11.950µs 11.975µs 12.000µs 12.025µs 12.050µs 12.075µs 12.100µs 12.125µs 12.150µs 12.175µs SPICE of Flyback in CCM V(d) 440V 400V 360V 320V 280V 240V 200V 160V 120V 80V 40V 0V -i(vin) 13A I(D1) 12A 11A 10A 9A 8A 7A 6A 5A 4A 3A 2A 1A 0A -1A I(Lm) 11.7A 11.4A 11.1A 10.8A 10.5A 10.2A 9.9A 9.6A 9.3A 9.0A V(sa) 120V 100V 80V 60V 40V 20V 0V -20V -40V -60V -80V -100V 4.9µs 5.1µs 5.3µs 5.5µs 5.7µs 5.9µs 6.1µs 6.3µs 6.5µs 6.7µs 6.9µs 7.1µs 7.3µs 7.5µs 7.7µs 7.9µs 8.1µs 8.3µs 8.5µs 8.7µs 8.9µs 9.1µs 9.3µs 9.5µs 9.7µs 9.9µs 10.1µs SPICE Deck * test of lossless single-switch flyback converter! ! .param Vin=170 Vout=80! .param Cr=10n! .param Tcy=10u Tw=2u Ncy=3! .model D1 D(Ron=0.01 Roff=1000k Vfwd=0.4)! ! VIN IN 0 {Vin}! VOUT OUT 0 {Vout}! ! * Transformer ! LPL IN P1 1u! RP P1 P2 0.01! LPM P2 D 20u! LP P2 D 4m! LS 0 S1 1m! K LP LS 1 ! ! * switch! S1 D 0 G 0 SW1! .model SW1 SW(Ron=.01 Roff=1000k Vt=5)! DS1 0 D D1! ! * Output diode! DLS S1 OUT D1! ! * recovery! DR1 D CRP D1! VR CRP 0 450! ! * pulse! VG G 0 PULSE(0 15 0 10n 10n {Tw} {Tcy} {Ncy})! ! .ic v(CRN) 0! .ic v(D) 160! .ic I(LP) 0! .ic I(LPM) 0! ! .tran {Tcy*Ncy}! ! Forward Converter Forward Converter With Lm and Ll Forward Converter Operation Phases 1. Primary current ramps in LL (secondary shorted) 2.  Primary and secondary conduct (Vin across primary) 3.  Secondary current switches (secondary shorted) 4.  Recovery of LM energy (-Vin across recovery wdg) 5.  Off Forward Phase Vin across primary winding Secondary conducts Energy stored in Lm Recovery Phase -Vin across recovery winding Energy in Lm returned to supply Forward Converter SPICE V(d) 500V 400V 300V 200V 100V 0V -i(s1) 15A 12A 9A 6A 3A 0A I(Lsx) 14A I(Lp) -i(ls) 6A -2A V(s1) 180V 90V 0V -90V -180V V(r) 360V 165V -30V I(Lr) 1.5A 0.7A -0.1A I(Lpm) 1.5A 0.7A -0.1A 9.9µs 10.5µs 11.1µs 11.7µs 12.3µs 12.9µs 13.5µs 14.1µs 14.7µs 15.3µs 15.9µs 16.5µs 17.1µs 17.7µs 18.3µs 18.9µs 19.5µs Forward Converter – Zoom of Commutation V(d) 500V 400V 300V 200V 100V 0V 15A 12A 9A 6A 3A 0A 14A -i(s1) I(Lsx) I(Lp) -i(ls) 6A -2A V(s1) 180V 90V 0V -90V -180V V(r) 360V...
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