Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Power electronic drives ppt

49,559 views

Published on

Published in: Education
  • Be the first to comment

Power electronic drives ppt

  1. 1. ELECTRICAL DRIVES: An Application of Power Electronics
  2. 2. CONTENTS Power Electronic Systems Modern Electrical Drive Systems Power Electronic Converters in Electrical Drives :: DC and AC Drives Modeling and Control of Electrical Drives
  3. 3. Power Electronic Systems What is Power Electronics ? A field of Electrical Engineering that deals with the application of power semiconductor devices for the control and conversion of electric power Input Source - AC - DC - unregulated Reference sensors Power Electronics Power Electronics Converters Converters Load Load Output - AC - DC Controller Controller POWER ELECTRONIC CONVERTERS – the heart of power a power electronics system
  4. 4. Power Electronic Systems Why Power Electronics ? Input Source - AC - DC - unregulated Reference sensors Power Electronics Power Electronics Converters Converters IDEALLY LOSSLESS !! Load IDEALLY LOSSLESS Load Output - AC - DC Controller Controller
  5. 5. Power Electronic Systems Why Power Electronics ? Other factors: • Improvements in power semiconductors fabrication • Power Integrated Module (PIM), Intelligent Power Modules (IPM) • Decline cost in power semiconductor • Advancement in semiconductor fabrication • ASICs • Faster and cheaper to implement complex algorithm • FPGA • DSPs
  6. 6. Power Electronic Systems Some Applications of Power Electronics : Typically used in systems requiring efficient control and conversion of electric energy: Domestic and Commercial Applications Industrial Applications Telecommunications Transportation Generation, Transmission and Distribution of electrical energy Power rating of < 1 W (portable equipment) Tens or hundreds Watts (Power supplies for computers /office equipment) kW to MW : drives Hundreds of MW in DC transmission system (HVDC)
  7. 7. Modern Electrical Drive Systems Classic Electrical Drive for Variable Speed Application : • Bulky • Inefficient • inflexible
  8. 8. Modern Electrical Drive Systems Typical Modern Electric Drive Systems Electric Motor Power Electronic Converters Electric Energy - Unregulated - POWER IN Electric Energy - Regulated - Power Power Electronic Electronic Converters Converters Moto Moto rr feedback Reference Controller Controller Electric Energy Mechanical Energy Load Load
  9. 9. Modern Electrical Drive Systems Example on VSD application Variable Speed Drives Constant speed valve Supply motor pump Power out Power In Power loss Mainly in valve
  10. 10. Modern Electrical Drive Systems Example on VSD application Variable Speed Drives Constant speed valve Supply motor Supply pump PEC Power out Power In motor pump Power out Power In Power loss Mainly in valve Power loss
  11. 11. Modern Electrical Drive Systems Example on VSD application Variable Speed Drives Constant speed valve Supply motor Supply pump PEC Power out Power In motor pump Power out Power In Power loss Mainly in valve Power loss
  12. 12. Modern Electrical Drive Systems Example on VSD application Electric motor consumes more than half of electrical energy in the US Fixed speed Variable speed Improvements in energy utilization in electric motors give large impact to the overall energy consumption HOW ? Replacing fixed speed drives with variable speed drives Using the high efficiency motors Improves the existing power converter–based drive systems
  13. 13. Modern Electrical Drive Systems Overview of AC and DC drives DC drives: Electrical drives that use DC motors as the prime mover Regular maintenance, heavy, expensive, speed limit Easy control, decouple control of torque and flux AC drives: Electrical drives that use AC motors as the prime mover Less maintenance, light, less expensive, high speed Coupling between torque and flux – variable spatial angle between rotor and stator flux
  14. 14. Modern Electrical Drive Systems Overview of AC and DC drives Before semiconductor devices were introduced (<1950) • AC motors for fixed speed applications • DC motors for variable speed applications After semiconductor devices were introduced (1960s) • Variable frequency sources available – AC motors in variable speed applications • Coupling between flux and torque control • Application limited to medium performance applications – fans, blowers, compressors – scalar control • High performance applications dominated by DC motors – tractions, elevators, servos, etc
  15. 15. Modern Electrical Drive Systems Overview of AC and DC drives After vector control drives were introduced (1980s) • AC motors used in high performance applications – elevators, tractions, servos • AC motors favorable than DC motors – however control is complex hence expensive • Cost of microprocessor/semiconductors decreasing –predicted 30 years ago AC motors would take over DC motors
  16. 16. Modern Electrical Drive Systems Overview of AC and DC drives
  17. 17. Power Electronic Converters in ED Systems Converters for Motor Drives (some possible configurations) DC Drives DC Source AC Source DC-AC-DC DC-AC-DC AC-DC AC-DC AC Drives AC-DC-DC AC-DC-DC DC Source AC Source DC-DC DC-DC AC-DC-AC AC-DC-AC Const. DC Variable DC AC-AC AC-AC NCC FCC DC-AC DC-AC DC-DC-AC DC-DC-AC
  18. 18. Power Electronic Converters in ED Systems Converters for Motor Drives Configurations of Power Electronic Converters depend on: Sources available Type of Motors Drive Performance - applications - Braking - Response - Ratings
  19. 19. Power Electronic Converters in ED Systems DC DRIVES Available AC source to control DC motor (brushed) AC-DC AC-DC AC-DC-DC AC-DC-DC Uncontrolled Rectifier Control Controlled Rectifier Single-phase Three-phase Single-phase Three-phase Control DC-DC Switched mode 1-quadrant, 2-quadrant 4-quadrant
  20. 20. Power Electronic Converters in ED Systems DC DRIVES AC-DC AC-DC 400 200 0 + 50Hz 1-phase Vo = Vo 2Vm cos α π Average voltage over 10ms − -200 -400 0.4 0.405 0.41 0.415 0.42 0.425 0.43 0.435 0.44 0.405 0.41 0.415 0.42 0.425 0.43 0.435 0.44 10 5 0 0.4 500 0 50Hz 3-phase + Vo -500 Vo = 3VL −L,m π 0.4 cos α 0.405 0.41 0.415 0.42 0.425 0.43 0.435 0.44 0.405 0.41 0.415 0.42 0.425 0.43 0.435 0.44 30 20 − Average voltage over 3.33 ms 10 0 0.4
  21. 21. Power Electronic Converters in ED Systems DC DRIVES AC-DC AC-DC 2Vm π + 50Hz 1-phase Vo = Vo 2Vm cos α π 90o 90o Average voltage over 10ms − − 180o 180o 2Vm π 3VL −L,m 50Hz 3-phase π + Vo − Vo = 3VL −L,m π cos α Average voltage over 3.33 ms − 3VL −L ,m π
  22. 22. Power Electronic Converters in ED Systems DC DRIVES AC-DC AC-DC ia Vt + 3-phase supply Vt Q2 Q1 − Q3 Q4 - Operation in quadrant 1 and 4 only Ia
  23. 23. Power Electronic Converters in ED Systems DC DRIVES AC-DC AC-DC 3phase supply + 3-phase supply Vt − ω Q2 Q1 Q3 Q4 T
  24. 24. Power Electronic Converters in ED Systems DC DRIVES AC-DC AC-DC R1 F1 3-phase supply + Va F2 R2 ω Q2 Q1 Q3 Q4 - T
  25. 25. Power Electronic Converters in ED Systems DC DRIVES AC-DC AC-DC Cascade control structure with armature reversal (4-quadrant): iD ω ωref + _ Speed Speed controller controller iD,ref + Current Current Controller Controller _ iD,ref iD, Armature Armature reversal reversal Firing Firing Circuit Circuit
  26. 26. Power Electronic Converters in ED Systems DC DRIVES AC-DC-DC AC-DC-DC control
  27. 27. Power Electronic Converters in ED Systems DC DRIVES AC-DC-DC AC-DC-DC DC-DC: Two-quadrant Converter Va + T1 D1 ia Vdc − T2 D2 Q2 Q1 Ia + Va - T1 conducts → va = Vdc
  28. 28. Power Electronic Converters in ED Systems DC DRIVES AC-DC-DC AC-DC-DC DC-DC: Two-quadrant Converter Va + T1 D1 ia Vdc − T2 D2 Q2 Q1 Ia + Va - D2 conducts → va = 0 Va T1 conducts → va = Vdc Eb Quadrant 1 The average voltage is made larger than the back emf
  29. 29. Power Electronic Converters in ED Systems DC DRIVES AC-DC-DC AC-DC-DC DC-DC: Two-quadrant Converter Va + T1 D1 ia Vdc − T2 D2 Q2 Q1 Ia + Va - D1 conducts → va = Vdc
  30. 30. Power Electronic Converters in ED Systems DC DRIVES AC-DC-DC AC-DC-DC DC-DC: Two-quadrant Converter Va + T1 D1 ia Vdc − T2 D2 Q2 Q1 Ia + Va - T2 conducts → va = 0 Va D1 conducts → va = Vdc Eb Quadrant 2 The average voltage is made smallerr than the back emf, thus forcing the current to flow in the reverse direction
  31. 31. Power Electronic Converters in ED Systems DC DRIVES AC-DC-DC AC-DC-DC DC-DC: Two-quadrant Converter 2vtri + vA vc Vdc - 0 vc +
  32. 32. Power Electronic Converters in ED Systems DC DRIVES AC-DC-DC AC-DC-DC DC-DC: Four-quadrant Converter leg A + Q1 leg B D3 D1 + Va − Q3 Vdc − Positive current va = Vdc when Q1 and Q2 are ON Q4 D4 D2 Q2
  33. 33. Power Electronic Converters in ED Systems DC DRIVES AC-DC-DC AC-DC-DC DC-DC: Four-quadrant Converter leg A + Q1 leg B D3 D1 + Va − Q3 Vdc − Q4 D4 Positive current va = Vdc when Q1 and Q2 are ON va = -Vdc when D3 and D4 are ON va = 0 when current freewheels through Q and D D2 Q2
  34. 34. Power Electronic Converters in ED Systems DC DRIVES AC-DC-DC AC-DC-DC DC-DC: Four-quadrant Converter leg A + Q1 leg B D3 D1 + Va − Q3 Vdc − Q4 D4 Positive current va = Vdc when Q1 and Q2 are ON va = -Vdc when D3 and D4 are ON va = 0 when current freewheels through Q and D D2 Q2 Negative current va = Vdc when D1 and D2 are ON
  35. 35. Power Electronic Converters in ED Systems DC DRIVES AC-DC-DC AC-DC-DC DC-DC: Four-quadrant Converter leg A + Q1 leg B D3 D1 + Va − Q3 Vdc − Q4 D4 Positive current D2 Q2 Negative current va = Vdc when Q1 and Q2 are ON va = Vdc when D1 and D2 are ON va = -Vdc when D3 and D4 are ON va = -Vdc when Q3 and Q4 are ON va = 0 when current freewheels through Q and D va = 0 when current freewheels through Q and D

×