Lecture on IGBTs (Insulated Gate Bipolar Transistors)

Introduction

• Explanation of IGBT name: Derived from “Insulated Gate Bipolar Transistor.”
• Power electronics component combining features of MOSFET and BJT transistors.
• Commonly used for switching purposes in various applications, especially UPSs requiring high switching speeds.

IGBT Fundamentals

• Combination of MOSFET and BJT: Hybrid device
  • Insulated Gate: Refers to MOSFET’s high input impedance, operates on gate terminal voltage.
  • Bipolar: Refers to BJT’s bipolar nature, handles large currents and voltages via small voltage signals.
  • Voltage-controlled device.

Pin Configuration

• Three pins: Gate (G), Collector (C), Emitter (E).
  • Symbolism can vary.
• Shows both MOSFET and BJT features in the pin configuration.
  • Gate pin resembles MOSFET.
  • Collector and Emitter pins resemble BJT.

Working Principle

• Similar to MOSFET: Trigger voltage at Gate controls large current between Collector and Emitter.
• Voltage used for current control.

Advantages and Disadvantages

• Advantages:
  • Higher voltage and current carrying capabilities.
  • Very high input impedance.
  • Can switch high currents using low voltage.
  • Voltage-controlled, low input current and losses.
  • Higher power gain than both BJT and MOSFET.
  • Higher switching speed than a BJT.
• Disadvantages:
  • Lower switching speed than a MOSFET.
  • Potential locking problem due to PNPN structure.
  • More expensive than BJT and MOSFET.

Applications

• Used in both AC and DC circuits
• Important Applications:
  • SMPS (Switched Mode Power Supply): Powers sensitive medical equipment, computers.
  • UPS (Uninterruptible Power Supply): Provides energy during power outages by converting battery DC to AC.
  • Inverter circuits: Enable power conversion in various settings.
  • Solar inverters: Convert and store solar panel energy in batteries for home use.

Conclusion

• Basic structure and applications of IGBTs explained.
• Aim to provide useful and informative content.
• Closing remarks and invitation to future lessons.