WHAT IS POWER ELECTRONICS

The aim of power electronics is to optimize the power efficiency, minimal size, minimal weight and meeting the requirements for user loads by modifying the voltages and currents. Fig.1 shows a block diagram of a power electronic system. Power processors, depending on the application, the output of the load may have the following forms

DC: Regulated or adjustable magnitude.
AC: Constant frequency and adjustable magnitude or adjustable frequency and adjustable magnitude.

Figure 1: Block Diagram of a Power Electronic System

Power conversions (converters) consist of four different conversion functions as shown in Figure 2 and described in below.

AC-DC (rectification)

Possibly control DC voltage and AC current

Examples: Diode rectifiers and thyristor rectifiers.

DC-DC (conversion)

Modify and control voltage magnitude.

Examples: Buck and Boost Converters.

DC-AC (inversion)

Single and three-phase converters and different modulations schemes.

AC-AC (conversion)

Cycloconverter, Matrix Converter, AC choppers

Figure 2: a Power Electronic System with Four Possible Conversions

Power electronics can be used in different categories such as:

1. Switch-mode (dc) power supplies and uninterruptible power supplies

2. Energy conservation

3. Process control and factory automation

4. Transportation

Power electronics are widely used in modern days in applications where power processing is required such as:

Residential: Refrigeration and freezers, Air conditioning, Cooking, Lighting and Electronics.

Commercial: Uninterruptible power supplies (UPS), Heating, ventilating, and air conditioning, Lighting, and Computers and office equipment.

Industrial: Pump, Compressors, Machine tools, Welding and Induction heating.

Transportation: Battery chargers for electric vehicles, Cars, Buses, Subways and automotive electronics including engine controls.

Utility systems: High-voltage dc transmission (HVDC), Static VAR compensation (SVC), Supplemental energy sources (wind, photovoltaic), fuel cells, Energy storage systems and Induced-draft fans and boiler feed water pumps.

Aerospace: Space shuttle power supply systems, Satellite power systems and Aircraft power systems.

Telecommunications: Battery chargers and Power supplies (dc and UPS).

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