Lecture Notes: IGBT Working Logic, Features, and Applications

Introduction to IGBT

• IGBT: Insulated Gate Bipolar Transistor
• Combines features of MOSFET and BJT
• Used extensively in power electronics for switching purposes
  • Common in UPSs (Uninterruptible Power Supplies)

Basic Features

• Insulated Gate: High input impedance (like MOSFET)
  • Operates on gate voltage
• Bipolar: Current flow due to both types of charge carriers (like BJT)
  • Handles large currents and voltages
• Voltage-Controlled Device: Small voltage signals control large currents

IGBT Structure

• Three Pins: Gate (G), Collector (C), Emitter (E)
  • Symbol and pin configuration may vary
• Combines MOSFET (Gate) and BJT (Collector, Emitter) features
• Working Principle: Similar to MOSFET
  • Trigger voltage at Gate controls large current between Collector and Emitter

Advantages and Disadvantages

Advantages

• High voltage and current carrying capabilities
• Very high input impedance
• Switches high currents with low voltage
• Voltage-controlled, low input current and losses
• Higher power gain than BJT and MOSFET
• Higher switching speed than BJT

Disadvantages

• Lower switching speed than MOSFET
• Locking problem due to PNPN structure (like a thyristor)
• More costly than BJT and MOSFET

Applications of IGBT

• SMPS (Switched Mode Power Supply): Powers sensitive equipment like medical devices and computers
• UPS (Uninterruptible Power Supply): Provides power during outages by converting DC from batteries to AC
• Inverter Circuits: Used in power conversion for various applications
• Solar Inverters: Convert and store energy from solar panels for household use

Conclusion

• IGBTs combine the best features of MOSFETs and BJTs
• Have diverse applications in power electronics
• Important for systems that require efficient switching and power conversion

Hope you found this session useful. See you in the next lesson!