3. IGBT
(Insulated Gate Bipolar Transistor)
What does word stand for…..
Combination of BJT and MOSFET
Lab Symbol
Detailed description of symbol
{[(HOW)}
6. Working And Operation
Controlling factor: Gate Voltage
Called as voltage-controlled BJT
Input current zero at gate; as
insulated
Input is MOSFET characteristics
Output is BJT characteristics
Threshold Voltage
7. Working And Operation
npnp structure Thyristor
Parasitic transistor and resistence
no effect under normal operation
Max collector current
Parasitic transistor activates
Thus parasitic thyristor activates
Latch up condition dominates
i.e. IGBT will remain on
Cannot controlled by gate
voltage
8. How do IGBT LOOK like….
1RGT10075M12
5EMK80N
Internal Structure
Made in Italy
Made in China
A Dissectional view of
IGBT
• All of the IGBT’s related to any model do have the simplified
circuit drawn on it.
9. Importance & Advantages of IGBT
in Electrical & Electronics world
Combine features of MOSFET & BJT under single device
High current & High voltage Switching Applications, provides safe
gateway
Low on state voltage drop (MOSFET part) & High on state current
density; so smaller chip size & low cost manufacturing & production
Low voltage drop at input gate; so easily controlled compared to
thyristors & BJT’s.
High density current conduction provides excellent forward & reverse
blocking capabalites.
It can be used in every electronic and electrical circuits where high
switch repletion is need.
10. Applications of IGBT’s in Electrical &
Electronics World
Switch
Mode
Power Supplies
(SMPS)
Safe controlling to work with high
voltage or high current.
11. Uninterruptible Power
Supplies (UPS)
Old UPS gives audible irritating sound
IGBT use in UPS gives it high dynamic
range and low noise.
Ex: China company HOMAGE UPS
14. Switching Characteristics of IGBT’s
IGBT Switching Test Time Circuit
Switching Characteristics similar to Power
Mosfet
Difference is; tailing collector current due to
stored charge in N (negative) Drift region
Tail current increases turn off loss
Also increase the dead time between the
two devices in half-bridge circuit
Operates at -15V at gate to switch off
15. Turn off speed limited of IGBT (How)
Lifetime stored charge or minority carriers in N(-ve) drift-region
Base is parasitic PNP transistor
No External means to sweep the minority carriers from N(-ve) drift region
To improve Switching time N(+ve) buffer layer helps
16. References:
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Abdus Sattar 1XYS Corporation
Text book: Electronic Device and
Circuits by Floyd