Inroduction

POWER ELECTRONICS

Power electronics is a subject which deals with electricity as well as electronics. Electrical engineering is mainly concerned with generation, transmission, distribution & utilization of electrical energy. Electronics engineering on the other hand is guided by distortion less production, transmission and reception of data signals of very low power level , of the order of few watts.

The power engineering is based mainly on electromagnetic principles that are rated at power level rather than signal level. It may also defined as a subject which deals with the apparatus & working equipment on the principle of electronics but rated at power level rather than signal level.

Applications of power electronics :

1. In commercial such as advertising, heating, unintereupted power supply, elevators, light dimmers and flashers.

2. In aerospace such as space shuttle power supplies, satillites power supplies, aircraft power system.

3. In industries such as blowers, fans, pumps, compressors, industrial lasers , rolling mills, cement mills, welding.

4. In residential such as air conditioning, cooking, lighting, refrigerators, personal computers, electronic door openers, dryers, vaccum cleaners, washing & sewing machines, light dimmers, food mixers.

5. In transportation such as battery charges, traction control of electric vechiles, electric locomotives, street cars, trolley buses, subways, automotive electronics.

6. In Utility systems such as High voltage DC transmission (HVDC), excitation system, VAR compensation, static circuit breakers, fans and boiler feed pumps.

Advantages of power electronics :

1. High efficiency due to low loss in power semiconductor drives.

2. High reliability of power electronic converter systems.

3. Long life and less maintanence due to absence of moving parts.

4. Fast dynamic response.

5. The cost of converter equipment is less.

Disadvantages of power electronics :

1. It generates harmonics in the supply system.

2. The converters operates at low power factor. To improve the power factor we need some special measures.

3. Power electronics controller cost is high when it operates at high load capacity.

4. Regeneration of power is difficult in power electronic converter system.