Power
electronics is a subject or a field which combines the knowledge of Power
(Electric Power), Electronics and Control System to process and control the
flow of electric power by supplying voltages and currents in the form optimally
suited for user load. 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 i.e. to control the output voltage and output power. So power
electronics may be defined as the subject of applications of solid state power
semiconductor devices for the control and conversion of electric power. The
basic block diagram of power electronics is shown in fig 1 below.
Fig
1: Basic block diagram of Power Electronics
Power electronics refers to control & conversion of electrical power by power semiconductor devices where these devices operate as switch. Power electronics uses new switches circuit topologies to make smaller lower weight & higher efficiency power supplier from 1W to MW levels. Power electronics is defined as a subject that deals with the apparatus and equipment working on the principle of electronics but rated at power level rather than signal level.
Example: Semiconductor power switches such as thyristors, GTOs, etc.
The
main goal of power electronics is to convert the electrical energy from one
form to another form and also to control the flow of energy from an electrical
source to an electrical load with highest efficiency, high availability and
high reliability with the lowest cost, smallest size and light weight. Power
electronics deals with the study and design of Thyristorised power controllers
for variety of applications like Heat Control, Light Illumination Control and
Motor control – AC/DC motor drives used in industries. Today power electronics
systems are widely spread for adapting energy to the load in many different
cases in industries, transportation and household, e.g.
- · Power supply and electrical transmission e.g. high voltage DC lines (HVDC)
- · Electric drives in electric cars, trams, locomotives and many other cases
- · Electric drives in conveying devices, rolling mills, machine tools and others
- · Power supply for welding, electroplating and electrolysis
- · Power supply for consumer goods, e.g. switching mode power supply for computers, TV and many more other products, furthermore light dimming, speed control of fans, vacuum cleaners and many others electric appliances.
The
main task of power electronics is to convert and control the electric power,
i.e. for the control of electric power or power conditioning, the conversion of
electrical power from one form to another form is necessary and the switching
characteristics of power devices permits these conditions. The static power
converters perform these functions of power conversions. A converter may be
considered as a switching matrix. The four main forms of conversions are:
Ø AC to DC Conversion (Rectification)
Ø AC to AC Conversion (Phase
Controlled Rectifiers)
Ø DC to DC Conversions (DC Choppers)
Ø DC to AC Conversions (Inverters)
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