GATE Electrical – Power Electronics
Module 1: Power Semiconductor Devices
Topic 1: Power Diode – Complete Theory
1. Introduction to Power Electronics
Power Electronics deals with the control and conversion of electrical power using semiconductor switching devices.
It combines:
- Power Engineering
- Electronics
- Control Systems
Main Objective: Efficient conversion of power from one form to another.
2. Power Semiconductor Devices
Power semiconductor devices are electronic switches that handle high voltage and current.
- Power Diode
- SCR (Thyristor)
- MOSFET
- IGBT
- GTO
3. Power Diode
3.1 Definition
A Power Diode is an uncontrolled semiconductor device that allows current to flow in only one direction and blocks current in the reverse direction.
3.2 Construction
Power diode is similar to a PN junction diode but:
- It has a larger junction area
- It can handle high current
- It can withstand high reverse voltage
- It has a thick N- drift region
Structure: P+ – N- – N+
3.3 V-I Characteristics
Forward Bias Region
- Current flows after threshold voltage
- Low forward resistance
Reverse Bias Region
- Small leakage current flows
- Blocks reverse voltage up to breakdown
3.4 Important Parameters
- Forward Voltage Drop (VF)
- Reverse Breakdown Voltage (VBR)
- Reverse Recovery Time (trr)
- Average Forward Current
- Peak Inverse Voltage (PIV)
3.5 Reverse Recovery Time
Reverse recovery time is the time taken by the diode to switch from forward conduction to reverse blocking mode.
This is very important in high frequency applications.
3.6 Types of Power Diodes
- General Purpose Diode
- Fast Recovery Diode
- Schottky Diode
4. Applications
- Rectifiers
- Freewheeling Diodes
- Clipping Circuits
- Snubber Circuits
5. GATE Important Points
- Understand PIV clearly
- Reverse recovery is very important
- Know ideal vs practical diode
- Waveform understanding is key
Shaktimatha Learning – Structured Electrical Engineering Preparation
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