Post on 01-Jan-2016
description
ECE 442 Power Electronics 1
IGBT: Insulated-Gate Bipolar Transistor
• Combination BJT and MOSFET– High Input Impedance (MOSFET)– Low On-state Conduction Losses (BJT)
• High Voltage and Current Ratings
• Symbol
ECE 442 Power Electronics 2
Cross-Sectional View of an IGBT
Metal
Silicon Dioxide
Metal
ECE 442 Power Electronics 3
IGBT Equivalent Circuit for VGE<VT
+
VCCIEPNP
ICPNP
IBPNP
ICNPN
IENPN
IBNPN
Leakage Current
IRBE
Both transistors are OFF
ECE 442 Power Electronics 4
IGBT Equivalent Circuit for VGE>VT
+
VCC
NPN Transistor becomes forward biased at the BE, drawing current from the Base of the PNP transistor.
MOS transistor conducts, drawing current from the Base of the PNP transistor.
PNP transistor turns ON,
RMOD decreases due to carrier injection from the PNP Emitter.
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Channel is Induced When VGE>VT
Induced Channel
electrons
RMOD PNP
RBE
NPN
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IGBT Output Characteristics
Follows an SCR characteristic
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IGBT Transfer Characteristic
ECE 442 Power Electronics 8
IGBT Used as a Switch
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Fairchild FGA25N120AND IGBT
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ECE 442 Power Electronics 15