Power Electronics

Power electronics is one of the important branches of electronics and electrical engineering. It deals with conversion and control of energy. We know that AC voltage and current of fixed frequency is available from mains. This supply cannot be used always directly. For example computer needs SMPS (Switched Mode Power Supply) for its working. There are numerous applications coming up every day in power electronics. Some of them are mentioned below:

• Uninterruptible power supplies and stand by power supplies (emergency power supplies) for critical loads such as computers, medical equipments etc.
• Power control in resistance welding induction heating, electrolysis, process industry etc.
• Power conversion for HVDC and HVAC transmission systems.
• Speed control of motors which are used in traction drives, textile mills, rolling mills, cranes, lifts, compressors, pumps etc.
• Solid state power compensators, static contactors, transformer tap changers etc.
• High voltage supplies for electrostatic precipitators, and x-ray generators, etc.
• Power supplies for communication systems, telephone exchanges, satellite systems etc.

Advantages and Disadvantages of Power Electronic Controllers

The control and conversion of electric power is performed with the help of power electronic controllers. Thus power electronic systems consist of controllers. The power electronic controllers are also called as power electronic converters. The power electronic controllers have following advantages : 

• Fast dynamic response due to static devices.
• High efficiency of conversion due to low losses in electronic devices.
• Compact size and light weight of the controllers due to electronic devices.
• Increased operating life and reduced maintenance since there are no moving parts.
• Power electronic controllers use digital or microprocessor based control. Hence their operation is highly flexible.
• Since solid state devices are used, the electromagnetic interference and acoustic noise is reduced.

The power electronic controllers have some drawbacks also. They are as follows:

• The power electronic controllers generate harmonics. These harmonics affect the performance of other loads.
• The power factor of some power electronic controllers is very low. Hence power factor correction is necessary to reduce reactive power.
• For very simple conversion requirements, power electronic converters may be costly.

Questionnaire:

• What is power electronics? Explain.