Power Electronics

  Introduction to power electronics:

            Power Electronics is a field which combines Power (electric power), Electronics and Control systems. 
Power engineering deals with the static and rotating power equipment for the generation, transmission 
and distribution of electric power. Electronics deals with the study of solid state semiconductor power 
devices and circuits for Power conversion to meet the desired control objectives (to control the output 
voltage and output power). Power electronics may be defined as the subject of applications of solid state 
power semiconductor devices (Thyristors) for the control and conversion of electric power. Power 
electronics deals with the study and design of Thyristorised power controllers for variety of application 
like Heat control, Light/Illumination control and Motor control - AC/DC motor drives used in industries, 
High voltage power supplies, Vehicle propulsion systems, High voltage direct current (HVDC) 
transmission. 
Power Electronics refers to the process of controlling the flow of current and voltage and converting it to 
a form that is suitable for user loads. The most desirable power electronic system is one whose efficiency    and reliability is 100%.
                   

     Power electronic applications 

  1.  Commercial applications  Heating                 Systems Ventilating, Air Conditioners,           Central Refrigeration, 

      Lighting, Computers and Office                     equipments, Uninterruptible Power              Supplies (UPS), Elevators, and 

        Emergency Lamps 

2.Domestic applications .Cooking                        Equipments, Lighting, Heating, Air                Conditioners, Refrigerators & 

    Freezers, Personal Computers,                       Entertainment Equipments, UPS

  3. Industrial applications .Pumps,                        compressors, blowers and fans                      Machine  tools, arc furnaces,                           induction 

        furnaces, lighting control circuits,                   industrial lasers, induction heating,               welding equipments 

  4. Aerospace applications .Space shuttle           power supply systems, satellite power          systems, aircraft power 

          systems. 

     5. Telecommunications Battery                          chargers,         power supplies (DC and          UPS), mobile         cell phone battery 

       chargers 

6. Transportation  .Traction control of               electric vehicles, battery chargers for           electric vehicles, electric 

      locomotives, street cars, trolley buses,          automobile electronics including                    engine controls 

7.Utility systems . High voltage DC                      transmission (HVDC), static VAR                    compensation (SVC), Alternative 

      energy sources (wind, photovoltaic),           fuel cells, energy storage systems,                induced draft fans and boiler feed 

     water pumps 

    Types of power electronic                                converters 

1. Rectifiers (AC to DC converters): These converters convert constant ac voltage to variable dc 

output voltage.

2. Choppers (DC to DC converters): Dc chopper converts fixed dc voltage to a controllable dc 

output voltage.

3. Inverters (DC to AC converters): An inverter converts fixed dc voltage to a variable ac output 

voltage.

4. AC voltage controllers: These converters converts fixed ac voltage to a variable ac output voltage 

at same frequency.

5. Cycloconverters: These circuits convert input power at one frequency to output power at a 

different frequency through one stage conversion.