Power Electronic

INTRODUCTION

Power natural philosophy partially begins to power engineering and partially to natural philosophy engineering. Power engineering is principally involved with generation, transmission distribution and utilization of electrical energy at higher potency. natural philosophy engineering is target-hunting by distortionless production, transmission and reception of knowledge and signals of a really low power level.

Power physical science could be a subject that considerations the applications of electronic principles into things that area unit rated at power instead of signal levels.

Few Power Electronics Applications

 

Telecommunication	Battery chargers
Commercial	Elevators, Light dimmers
Aerospace	Satellite power supply
Industrial	Compressors, industrial lasers
Residential	Air-conditioning, cooking, dryers and fans

Advantages of Power Electronics

• Fast dynamic response
• Long life and less maintenance
• Small size and less weight
• High reliability
• Higher efficiency due to low loss

Disadvantages of Power Electronics

 

• It has a low overload capacity
• In Load circuit, the performance of load is influenced.
• A tendency to generate harmonics.
• Regeneration of power is difficult.
• AC to DC and AC to AC converters operate at low input powers factor under certain operating conditions.

Power electronic systems

 

1. Main unit (switching unit).
2. Control unit (PWM unit).
3. Feed back unit.

1.Main unit [Power electronic circuit]

This unit is major a part of any power electronic circuit. it’s changed a part of the ability electronic circuit. This section does all necessary variety of conversion like (AC to AC, AC-DC, DC-AC and DC-DC conversion)

• AC-AC converter – AC voltage regulator, cyclo-converter matrix converter.
• AC-DC converter – Phase control rectifier, SMPS
• DC-AC converter – Inverters
• DC-DC converter – Choppers

2.Control unit (PWM unit)

Control unit is answerable for generating PWM pulse (or) alternative sort pulse. the supported demand of load the management unit generates the PWM signals for the switch circuit. Recent years several kinds of management algorithms area unit developed to supply optimized output for the load.

3.Feedback unit

Satisfying the load demand is final aim of any power natural philosophy unit. The load may well be any kind R, RL load, RC load, motor etc.

In order to produce constant (or) optimal output to load, a part of the output voltage (or) current is feedback to the control unit.

S/L NO.	Name of the device	Type of conversion
1.	AC-DC converter (phase controlled rectifier)	constant AC voltage to variable DC output voltage
2.	Diode Rectifier	variable AC input to fixed DC voltage
3.	DC-AC converters (inverter)	fixed AC to variable ac
4.	DC-DC converters (choppers)	fixed DC input to controllable DC output voltages
5.	Static switches	A device that transfers electrical source to another source without interruption.
6.	AC-AC converters (a) AC voltage controllers (b) Cyclo-converters	fixed AC input to variable AC output voltage. fixed AC voltage to variable AC voltage. Convert input power at one frequency to output power at the different frequency.

Classification of various semiconductor devices

Based on (i) turn-ON and turn-OFF characteristics. (ii) the degree of controllable, power semiconductor devices can be classified as follows. (iii) gate signal requirements.

1. Thyristor: Controlled turn-on by a gate signal. After thyristor is ON, they remain latched in the state due to an internal action of gate losses control. Turning off can be achieved by the power circuit.

Ratings: 6000 V, 3500 A, 1 kHz

2. Diodes: Uncontrolled rectifying devices ON and OFF states are controlled by the power supply.

Ratings: 3000 V, 3500 A, 1 kHz.

3. Controllable switches: These can be turned-ON and turned-OFF by the application of control signals.

Example: BJT, MOSFET, GTO, SITH, IGBT, SIT, MCT.

3.Feedback unit

Satisfying the load demand is final aim of any power natural philosophy unit. The load may well be any kind R, RL load, RC load, motor etc.

Table: voltage, current and frequency rating of the power semiconductor device

SL NO.	Name of the device	Voltage, current and frequency rating
1.	MOSFET	1000 V, 50 A, 100 kHz
2.	BJT	1200 V, 400 A, 10 kHz
3.	MCT	600 V, 60 A, 20 kHz
4.	IGBT	1200 V, 400 A, 20 kHz
5.	GTO	4000 V, 3000 A, 10 kHz