Power Electronics System
Power Electronics Introduction:
Power Electronics is the study of electronic circuits used to convert and control the flow of electrical power.
[In other words]
Power Electronics deals with the applications of solid state electronic devices in the control and conversion of electric power.
Power Electronics can be described as an area where anything from a few watts to over several thousand watts are controlled by modern semiconductor control elements which consume only few micro watts to milliwatts in most areas.
Power Electronics embraces the studies of:-
It deals with both rotating and static equipment for the generation, transmission, distribution and utilisation of vast quantities of electrical power.
It deals with the study of semiconductor devices and circuits for the processing of information at lower power levels.
In deals with the stability and response characteristics of closed loop system.
Power Electronics deals with the use of electronics for control and conversion of large amount of electrical power.
Representation of Power Electronic System:-
The Block diagram of Power Electronics System is given below.
- The main power source may be either AC or DC based on the application
- The output of the power electronic circuit may be variable ac or dc, or it may be variable voltage and frequency based on the requirement. It is also known as power electronics conversion circuit. It can be described as a group of electrical and electronic components arranged to form an electric power from one form to another.
- The feedback component measures a parameter of the load(say for example speed) and compares it with the command signal
- The difference between these two signals, through the digital circuit controls the instant of turn on of the semiconductor device.
- The load circuit can be controlled over a wide range with the adjustment of the command signal.
- In between Power Electronic circuit to load, the Filter is added in most of the applications.
- A filter is necessary to prevent any harmonics generated by the converter from being feedback to the mains or from being radiated into space.
Advantages of Power Electronics System:-
- High efficiency due to low loss in power semiconductor devices.
- High reliability of power electronic converter system.
- Long life and less maintenance due to absence of any moving parts.
- Flexibility in operation
- Fast dynamic response compared to electromechanical converter system.
- Small size and less weight, thus low installation cost.
Disadvantages of Power Electronics System:-
- Circuits in power electronics system have a tendency to generate harmonics in the supply system as well as the load circuit.
- AC to DC and AC to AC converter operate at low input power factor under certain operating condition.
- Regeneration of power is difficult in power electronic converter system.
- Power Electronic controllers have low overhead capacity
Power Electronics Applications:
Typical power electronics applications include electronic ballasts, high voltage DC transmission systems (HVDC systems), power conditioners, UPS systems, power supplies, motor drives, power factor correction, rectifier, electric vehicles etc. With computer systems, telecom products and electronic consumer appliances which require many power electronic sub-systems, the power electronics industry has become an important topic in the electronics industry and the information technology area.