Power electronics overview

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here you can see in a glance what we study in power electronics field

here you can see in a glance what we study in power electronics field

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  • 1. 04/15/14 “IN THE NAME OF ALLAH THE MOST MERCIFULAND THE MOST BENEFICIAL”
  • 2. 04/15/14 POWER ELECTRONICS Presented By: Engr.Tafseer Ahmed BS in Electrical (Electronics) Engineering CIIT, Abbottabad a.tafseer@gmail.com
  • 3. 04/15/14 What is Power Electronics Power electronics deals with the applications of power semiconductor devices such as Thyristor and transistors for the conversion and control of electrical energy at high power levels.
  • 4. 04/15/1404/15/14 4 Relationship of Power Electronics
  • 5. 04/15/14 Elements of Power Electronics • Analogue circuits • Control Systems • Power Systems • Electronics Devices • Electric Machines • Numerical Simulation
  • 6. 04/15/14 POWER ELECTRONICS MAIN AREAS • As the technology for the power semiconductor devices and integrated circuit develops, the potential for applications of power electronics become wider. The power semiconductor devices or power electronic converter fall generally into four categories : • Thyristor Devices • AC to DC Converter (Controlled Rectifier) • DC to DC Converter (DC Chopper) • AC to AC Converter (AC voltage regulator) • DC to AC Converter (Inverter)
  • 7. 04/15/14 Diagram Block of Converters
  • 8. 04/15/14 • AC to DC Converters: An AC to DC converter circuit can convert AC voltage into a DC voltage. The DC output voltage can be controlled by varying the firing angle of the thyristors. The AC input voltage could be a single phase or three phase. • AC to AC Converters: This converters can convert from a fixed ac input voltage into variable AC output voltage. The output voltage is controlled by varying firing angle of TRIAC. These type converters are known as AC voltage regulators. • DC to DC Converters : These converters can converte a fixed DC input voltage into variable DC voltage or vice versa. The DC output voltage is controlled by varying of duty cycle. • DC to AC Converters: These converters can convert a constant DC input voltage into a variable AC voltage with variable frequency.
  • 9. 04/15/14 9
  • 10. 04/15/14 10
  • 11. 04/15/14 11
  • 12. 04/15/14 12
  • 13. 04/15/14 1.Uncontrolled turn on and off (Power Diode) 2.Controlled turn on uncontrolled turn off (Thyristors) 3.Controlled turn on and off characteristic (Power Transistor, BJT, MOSFET, GTO, IGBT) 4.Continuous gate signal requirement (BJT, MOSFET, IGBT) 5.Pulse gate requirement (SCR(Silicon-Controlled Rectifier) , GTO) 6.Bidirectional current capability (TRIAC) 7.Undirectionalcurrent capability (SCR, GTO, BJT, MOSFET, IGBT) POWER ELECTRONIC SWITCHING DEVICES
  • 14. 04/15/14 COMMONLY USED DEVICES • Power Diodes • Power Transistors • Thyristor Family • SCR( Silicon Controlled Rectifier) • SCS( Silicon controlled Switch) • GTO( Gate Turnoff Thyristor ) • The DIAC • The TRIAC • MCT( The MOS-Controlled Thyristor)
  • 15. 04/15/14 Devices Along with Symbols & Characteristics
  • 16. 04/15/1404/15/14 16 Power Ratings of Devices
  • 17. 04/15/1404/15/14 17 Ratings of Power Devices
  • 18. 04/15/1404/15/14 18 Applications of Power Devices
  • 19. 04/15/1404/15/14 19 Control Characteristics of Devices
  • 20. 04/15/1404/15/14 20 Control Characteristics of Devices
  • 21. 04/15/1404/15/14 21 Uncontrolled Rectifiers (AC to DC) ( ) 2 m o average V V π =
  • 22. 04/15/14 Controlled Rectifier( AC to DC) • AC to DC Converters -Single phase, half wave AC to DC converter Input voltage Output average voltage : rms value of Output voltage : Waveform of single-phase, half wave AC to DC converter α
  • 23. 04/15/14 23 AC-DC Rectifier( Full Wave)
  • 24. 04/15/1404/15/14 24 ( ) (1 cos )m o V V average α π = + 1 sin 2 (( ) ) 22 m rms V V α π α π = − +
  • 25. 04/15/1404/15/14 25 AC-AC (Voltage Regulator) 1/2 ( ) 1 sin 2 22 m o rms V V α π α π    = − + ÷    
  • 26. 04/15/1404/15/14 26 AC to DC Converters Single phase, Full wave AC to DC converter The average output voltage can be found from :
  • 27. 04/15/1404/15/14 27 AC to DC Converters Three-phase, Half wave AC to DC converter If the phase voltage is : van= Vm Sin(wt). The average output voltage for a continuous load current is :
  • 28. 04/15/1404/15/14 28 AC to DC Converters Three-phase, Full Wave AC to DC converter
  • 29. 04/15/1404/15/14 29 DC-DC CONVERTER (DC Chopper) • In many industrial application , DC-DC converter is required to convert a fixed-voltage DC source into a variable-voltage DC source. Like a transformer, DC-DC converter can be used to step down or step up a DC voltage source. • Application : Traction motor control in electric automobiles, trolley cars, marine hoists, forklift trucks, mine haulers, etc • Advantages : High Efficiency and fast dynamic response
  • 30. 04/15/1404/15/14 30 DC-DC CONVERTER (DC Chopper) Principle Of Step-Down Operation When the switch SW is closed for a time t1, the input voltage Vs appears across the load Vo = Vs. If the switch remains off a time t2, the voltage across the load is zero, Vo= 0. The converter switch SW can be implemented by using Transistor, MOSFET, GTO, IGBT, BJT, etc.
  • 31. 04/15/1404/15/14 31 The average output voltage is given by : The average output current is given by : The rms output voltage is given by : = Where : T is the chopping period k = t1/T is the duty cycle f = 1/T is chopping frequency
  • 32. 04/15/1404/15/14 32 STEP UP DC to DC CONVERTER When switch SW is closed for t1, the inductor current rises and energy is stored in the inductor L. If the switch SW is opened for time t2, the energy stored in the inductor is transferred to load through diode D1and the inductor current falls.
  • 33. 04/15/1404/15/14 33 When this DC to DC converter is turned on “switch SW is closed, the voltage across the inductor L is : And this gives the peak-to-peak ripple current in inductor as The average output voltage is :
  • 34. 04/15/1404/15/14 34 Buck – Boost Regulators • Abuck–boostRegulatorprovidesanoutputvoltagethatmaybelessthanorgreaterthantheinputvoltage-hencethename"buck-boost";the outputvoltagepolarityisoppositetothatoftheinputvoltage.thisregulatorisalsoknownasan invertingregulator. • Thecircuitoperationcanbedividedintotwomodes.duringmode1,transistorQ1isturnedonanddiodeDmisreversedbiased.theinputcurrent, whichrisesflowsthroughinductorLandtransistorQ1.Duringmode2,transistorQ1isswitchedoffandthecurrent,whichwasflowingthrough inductorL,wouldflow throughL,C,Dm,andtheload.TheenergystoredininductorLwouldbetransferredtotheloadandtheinductorcurrent wouldfalluntiltransistorQ1isswitchedonagaininthenextcycle.Theequivalentcircuitforthemodesareshowninthenextslide.
  • 35. 04/15/1404/15/14 35
  • 36. 04/15/1404/15/14 36 DC-AC Converter (Inverter) 1( ) 4 0.90 2 s o rms fundamental S V V V π − = =
  • 37. 04/15/14 37
  • 38. 04/15/14 38
  • 39. 04/15/1404/15/14 39 Examples of Some Applications
  • 40. 04/15/14