Dc drives

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Dc drives

  1. 1. DC Drive Systems Pekik Argo Dahono
  2. 2. DC Drive System
  3. 3. Block Diagram of DC Drives ~ Tl (s ) Ed ( s ) α (s) _ _ vD (s ) I a (s ) Te (s)ωr (s ) + + 1 + 1 ω (s ) ∑ Gω (s ) Ed ∑ Ra + sLa Kφ ∑ sJ _ _ Ea (s ) Kφ ω (s ) = (ω G ω ( s ) Ed / JLa ) ω ref ( s ) ( ) o s + sα + ω + ωo Gω ( s ) Ed / JLa 2 2 o ωo / JLa ~ − ( s 2 + sα + ωo + ωo Gω ( s ) Ed / JLa 2 ) Ed ( s ) − (s + α ) / J ( s + sα + ω + ωo Gω ( s ) Ed / JLa 2 2 o ) Tl ( s )
  4. 4. Single-Quadrant DC-DC Converter • The switching device is MOSFET for low-power, IGBT for medium power, and GTO for high power applications. • Single-quadrant is adequate when fast speed reversal and regenerative braking are not required. • Carrier signal is unipolar.
  5. 5. Two-Quadrant DC-DC Converter • Regenerative braking is possible. • If the source cannot accept the regenerated energy, the energy can be absorbed by a resistor that is connected in the dc side. • Carrier signal is unipolar. • This system is suitable for electric vehicles.
  6. 6. Four-Quadrant • Both output voltage and current are bidirectional. • Two splitting capacitors are required. • Carrier signal must be bipolar.
  7. 7. Four-Quadrant DC-DC Converter D1 D3 S1 vo S3 Suitable for robotic and machine M toolsEd S2 S4 D2 D4 S1 S2 S3 S4 Vo ON OFF ON OFF 0 ON OFF OFF ON Ed OFF ON ON OFF -Ed ON OFF ON OFF 0
  8. 8. Operating Principles of DC-DC Converters id iL di L R v D = Ri L + L + vo S L dt voEd D vD 0 ≤ t < TON vD = Ed di L id R iL E d = Ri L + L + vo dt S L vo TON ≤ t < TsEd D vD vD = 0 di L 0 = Ri L + L + vo TON vD = E d = αE d dt Ts
  9. 9. Operating Principles Ed Ed T vo vD vD = ON Ed vD Ts 0 0 TON α1Ts α 2Ts TON Ts TsE d − vo E d − vo vL vL −vo − vo iL 0 iL id v D = αE d v D ≠ αE d Continuous mode Discontinuous mode
  10. 10. Continuous Conduction Mode• The converter can be modeled as a variable dc voltage source or as a dc voltage amplifier.• The gain of amplifier is equal to the dc voltage source and the input signal is equal to the duty factor signal or equal to reference signal (if the amplitude of the carrier signal is equal to unity).• In single-quadrant chopper, both output voltage and current cannot be negative.• In two-quadrant chopper, the output voltage cannot be negative but the output current is bidirectional.• In four-quadrant chopper, both output voltage and current are bidirectional.• Nonidealities of amplifier can be represented as disturbance signal.
  11. 11. Single-Phase Fully-Controlled AC-DC Converter io vs is T1 T3 Ld ωt is vo + α iovs vo R 0 π 2π ωt T1 & T 4 T2 &T3 T2 T4 2 2 vo = cos α π
  12. 12. Three-Phase AC-DC Converter α vun vvn vwn 0 π 2π ωt vd ωt iu 3 2 vd = Vll cos α π
  13. 13. Four-Quadrant AC-DC ConverterConverter can be operated in either circulating or noncirculating current modes.
  14. 14. Continuous Conduction Mode• Under continuous conduction mode, the converter can be considered as a variable dc voltage source.• The output of dc voltage source is proportional to the cosinus of firing angle.• In fully controlled rectifiers, the output voltage is bidirectional but the output current is unidirectional.• In four-quadrant rectifier, both output voltage and current are bidirectional.
  15. 15. Current/Torque Controlled DC Drive Systems
  16. 16. Advantages Current-Controlled DC Drives• Short-circuit protection can be done inherently.• The design of speed controller is easy• The response is faster• The torque is proportional to the armature current.
  17. 17. Current-Controlled DC Drives
  18. 18. Block diagram of DC drive using current-controlled converter ~ Tl (s ) Ed ( s ) α (s) _ _ vD (s ) I a (s ) Te (s)ωr (s ) + + 1 + 1 ω (s ) ∑ Gω (s ) Ed ∑ Ra + sLa Kφ ∑ sJ _ _ Ea (s ) Kφ Voltage-controlled Current-Controlled
  19. 19. Block DiagramsI a (s) = Gc ( s ) Ed sLa + Ra + Gc ( s ) Ed I a (s) − ref 1 sLa + Ra + Gc ( s ) Ed [ ~ Ea ( s ) + Ed ( s ) ] Gω ( s ) KΦ 1 ω (s) = ωr (s) − Tl ( s ) sJ + Gω ( s ) KΦ sJ + Gω ( s ) KΦ
  20. 20. Current-Controlled DC-DC Converters• Hysteresis current controller• Carrier based current controller• Predictive controller
  21. 21. Hysteresis current controller IF ia > ia + h THEN S1 = OFF AND S2 = ON ref IF ia < ia − h THEN S1 = ON AND S2 = OFF ref
  22. 22. Simulated Result
  23. 23. Analysis 0 → TON dia ~ vD = Ed ia : −h → hv D = Ra ia + La + ea dt 2h = (1 − α )Ed T ON ~ Laia = ia + ia 2hLa ~ TON =v =v +v D D D (1 − α )Ed 0 → TOFFv D = Ra i a + e a = α E d ~ vD = 0 ia : h → −h ~ ~~ ~ d ia d ia − αE dv D = Ra ia + La ≈ La − 2h = La TOFF dt dt 2hLa TOFF =~ia = 1 ~ ∫ v D dt = 1 ∫ (v D − v D )dt αE d La La Ts = TON + TOFF f s = 1 / Ts = Ed (1 − α )α 2hLa
  24. 24. Carrier based current controller S1 Ia Ra La Ed S2 ea Ia + ref Current Regulator − ~ Current Ea ( s ) + Ed ( s ) controller _ α (s ) vD (s ) I a (s ) I a (s ) + ref + 1 ∑ Gω (s) Ed ∑ Ra + sLa _
  25. 25. Simulated Result
  26. 26. Predictive current controller v D − ea Δia = Ts La v D − ea ia (k + 1) − i (k ) = Ts La v D = αE d = [ La ia (k + 1) − ia (k ) ref ]+ ea Ts α= [ La ia (k + 1) − ia (k ) ea ref + ] Ts E d Ed
  27. 27. SimulationLimiterSpeedcontroller Current controller One-quadrant dc drive system
  28. 28. Simulation result The current cannot be negative
  29. 29. SimulationLimiterSpeedcontroller Current controller Two-quadrant dc drive system
  30. 30. Simulation Result
  31. 31. SimulationFour-quadrant dc drive system
  32. 32. Simulation Result
  33. 33. Simulation Result
  34. 34. Block Diagram of DC Drives Using AC-DC Converter AC source cosα α Converter and −1 cos DC output pulse gate generator 6 fLs I o − α + cosα cos −1 3 2 Vll cos π Vo 6 fLs I o − cosα + 3 2 Vll π Vo
  35. 35. Current-Controlled Rectifier AC source Io R L ref +Io cosα α Converter and Current cos−1 E Controller pulse gate generator − Ns − ref +Io Current cosα + 1 Io 3 2 Vll Controller π sL + R − − 6 fLs
  36. 36. Four-Quadrant AC-DC Converter Converter1 Converter 2 ia io 0 *ia + Current α1 + α 2 = π cos−1 controller −
  37. 37. Simulation
  38. 38. Simulation Result
  39. 39. Simulation
  40. 40. Simulated Result
  41. 41. Simulated Result
  42. 42. DC Drive Considerations• The input power factor is decreased when the speed is reduced.• The input current is rich in harmonics. The dominant harmonics are 5th and 7th order when three-phase six- pulse rectifier is used.• The converter generates notches in the input voltage.• Additional losses due to current ripple.• Separate fan must be provided when operating speed is low.• The dc motor cannot be operated under stalled conditions for a long time.• Comutator and brushes make the dc drive cannot be designed for very high speeds.
  43. 43. The End
  44. 44. TugasRancanglah pengendali kecepatan motor arus searah penguatan bebas (data ambil di literatur) 4-kuadran sebagai berikut:1) Konverter dc-dc 4-kuadran dengan pengendali arus hysteresis dan pengendali kecepatan PI.2) Konverter dc-dc 4-kuadran dengan pengendali arus hysteresis dan pengendali kecepatan IP.3) Konverter dc-dc 4-kuadran dengan pengendali arus PI dan pengendali kecepatan PI.4) Konverter dc-dc 4-kuadran dengan pengendali arus PI dan pengendali kecepatan IP.5) Konverter thyristor ac-dc 4-kuadran dengan pengendali arus PI dan pengendali kecepatan PI.6) Konverter thyristor ac-dc 4-kuadran dengan pengendali arus PI dan pengendali kecepatan IP.

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