All four switches on vin across input inductor

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

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...
View Full Document

This document was uploaded on 04/07/2014.

Ask a homework question - tutors are online