Xformer_Converters_102213

All four switches on vin across input inductor

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Unformatted text preview: 165V -30V I(Lr) 1.5A 0.7A -0.1A I(Lpm) 1.5A 0.7A -0.1A 14.6µs 14.7µs 14.8µs 14.9µs 15.0µs 15.1µs 15.2µs Using the B-H Curve •  Flyback and Forward converters only use half the B-H curve •  Also, each winding conducts only half the time •  Thus, they require larger magnetic components per unit power than would otherwise be required •  Bridge converters use the whole B-H curve and can e loss: Hysteresis loss conduct much of the cycle B B Area H dB one cycle olume of tegral is oop. (core volume) (area of B–H loop) H Full-Bridge Converter UL UR LL LR Full Bridge Operation 1.  UL and LR on –  Vin across primary –  NVin-Vout across inductor 2.  All off –  Leakage energy returned to supply –  Secondary shorted –  Magnetizing current circulates in secondary 3.  UR and LL on –  -Vin across primary –  NVin-Vout across inductor –  Magnetizing current balanced out 4.  All off (like 2) SPICE Waveforms for Bridge Converter v(l)-v(r) 180V 120V 60V 0V -60V -120V -180V -i(vin) 12A 8A 4A 0A -4A -8A -12A I(Lm) 240mA 160mA 80mA 0mA -80mA -160mA -240mA v(sa)-v(sb) 180V 120V 60V 0V -60V -120V -180V I(D1) 12A I(D2) I(D5) 6A -1A 11.2A 10.8A 10.4A 10.0A 9.6A 9.2A 8.8A 9.5µs I(L1) 10.0µs 10.5µs 11.0µs 11.5µs 12.0µs 12.5µs 13.0µs 13.5µs 14.0µs 14.5µs 15.0µs 15.5µs 16.0µs 16.5µs 17.0µs 17.5µs 18.0µs 18.5µs 19.0µs 19.5µs 20.0µs 20.5µs Current-Fed Bridge Current-Fed Bridge Operation 1.  All four switches on –  Vin across input inductor – current increases –  Primary shorted –  Output open 2.  UR and LL on –  Vin – NVout across input inductor – current decreases –  Vout across secondary –  Current delivered to output 3.  All four switches on (like 1) 4.  UL and LR on (like 2 but) –  -Vout across secondary SPICE Waveforms for Current-Fed Bridge v(l)-v(r) 480V 400V 320V 240V 160V 80V 0V -80V -160V -240V -320V -400V -480V I(L1) 12.0A 11.7A 11.4A 11.1A 10.8A 10.5A 10.2A 9.9A 9.6A 9.3A 9.0A I(Lm) 300mA 250mA 200mA 150mA 100mA 50mA 0mA -50mA -100mA -150mA -200mA -250m...
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This document was uploaded on 04/07/2014.

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