Introduction and semiconductor switches
Introduction to Power Electronics
Compiled by Engr. Raymond Paiton
What is Power Electronics?
Refers to solid-state electronic devices used for the conversion and control of electric power.
Integrates Electric Power, Electronics, and Control to manage power flow efficiently.
Functions of Power Electronics
Efficient control and conversion of electrical energy which includes:
Rectification: Converts AC to DC (e.g., from power sources like batteries, solar panels).
Inversion: Converts DC to AC for various applications.
Different applications include:
AC sources: single and three-phase AC to DC
DC loads: such as heaters, lamps, and motors.
Applications of Power Electronics
Commercial/Industrial Applications
Use in systems like:
Heating systems
Air conditioners
Refrigeration and lighting
Computers and office equipment
Uninterruptible Power Supplies (UPS)
Elevators
Domestic Applications
Essential in:
Cooking equipment
Lighting
Air conditioning
Refrigerators & freezers
Entertainment equipment
Personal computers
Aerospace Applications
Power systems for:
Satellites
Aircraft
Space shuttle power supply systems
Telecommunications
Used in:
Battery chargers
DC and UPS power supplies
Mobile phone battery chargers
Transportation
Applies in:
Electric vehicle traction control
Battery chargers
Electric locomotives and streetcars
Automotive electronic systems, including engine control.
Importance of Power Electronics
Fossil fuels continue to be the primary energy source (over 85%).
There’s a necessity to:
Use energy efficiently to address global warming.
Improve energy conversion efficiencies to minimize losses (e.g., saving energy in motor drives and chargers).
Integrate renewable energy sources into existing systems.
Efficiency Insights
Focus on improving efficiencies at front-end systems:
Example: Why work on motor efficiency when most losses are in the converter?
A push for higher efficiency circuits leads to saving significant power losses.
Power Loss Equations and Concepts
Basic formulas:
Pin = Pout + Ploss
Efficiency (n) calculated as: n = Pout / Pin
Pout = n * (Pin - Ploss)
Example calculations using efficiency values to highlight power losses.
Power Electronic Switches and Devices
Key components: Diodes, Transistors, Thyristors
Types of semiconductors used:
Silicon
Silicon Carbide (SiC)
Gallium Nitride (GaN)
Power Semiconductor Devices
Classifications:
General-Purpose: BJT, SCR, MOSFET
High-speed devices: IGBT, Schottky Diodes, and Triac.
Used mainly as on/off switches in power control circuits.
Power Electronic Topologies
Illustrates configurations to control power flow, using feedback and control signals for maintaining stability.
Components like MOSFETs and capacitors are key in different configurations.
Power Diodes Overview
Diode Characteristics
Diodes known for forward voltage drop, reverse bias current, forward recovery characteristics.
Different types include:
Fast Recovery Diodes, General-purpose Diodes, Schottky Diodes.
Diode Types and Characteristics
General-purpose Diodes: Used for rectification and protection.
Fast Recovery Diodes (FRD): Lower heat generation with a reduced reverse recovery time.
Schottky Barrier Diodes (SBD): Notable for low forward voltages and minimal recovery time but with high leakage current.
Series and Parallel Configuration of Diodes
In Series: Increases reverse blocking capabilities but may lead to uneven voltage sharing due to manufacturing tolerances.
In Parallel: Allows for increased current carrying capacity but requires careful balancing to prevent uneven current sharing.
Conclusions
Efficient design and deployment of power electronic circuits are essential for modern electrical systems, impacting everything from consumer electronics to large-scale industrial operations.