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Power Electronics

Power Electronics. UNIT-III PHASE CONTROLLED CONVERTERS Prof. V. N. Bhonge Dept. of Electronics & Telecomm Shri Sant Gajanan Maharaj College of Engg, Shegaon – 444203 vnbhonge@rediffmail.com. SSGMCE Shegaon. Unit II PHASE CONTROLLED CONVERTERS

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Power Electronics

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  1. Power Electronics UNIT-III PHASE CONTROLLED CONVERTERS Prof. V. N. Bhonge Dept. of Electronics & Telecomm Shri Sant Gajanan Maharaj College of Engg, Shegaon – 444203 vnbhonge@rediffmail.com

  2. SSGMCE Shegaon Unit II PHASE CONTROLLED CONVERTERS Principle of phase control, half wave controlled rectifier, half controlled bridge & fully controlled bridge rectifier for resistive and RL load, derivation for output voltage and current, effect of free wheeling diode, single phase dual converters. Three phase half controlled bridge and fully controlled bridge rectifier. Prof. V. N. Bhonge Dept. of E & TC

  3. Phase-Control Converters Single-Phase Three-Phase Semiconverter Semiconverter Full converter Full converter Dual converter Dual converter Prof. V. N. Bhonge Dept. of E & TC

  4. Semiconverter ..is a one-quadrant converter and it has one polarity Full converter ..is a two-quadrant converter and the polarity of its output can be either positive or negative. However the output current of full converter has one polarity only Dual converter ..can operate in four quadrants ; both the output voltage and current can be either positive or negative Prof. V. N. Bhonge Dept. of E & TC

  5. CONTROLLED RECTIFIER Phase controlled rectifier circuits Prof. V. N. Bhonge Dept. of E & TC

  6. Prof. V. N. Bhonge Dept. of E & TC

  7. Prof. V. N. Bhonge Dept. of E & TC

  8. Single-phase Half-wave Converter With R Load Prof. V. N. Bhonge Dept. of E & TC

  9. Single-Quadrant Operation Prof. V. N. Bhonge Dept. of E & TC

  10. Waveforms: Prof. V. N. Bhonge Dept. of E & TC

  11. Average Output Voltage Maximum Output Voltage Normalizing Output Voltage RMS Output Voltage

  12. Average Dc voltage & RMS across resistance load Prof. V. N. Bhonge Dept. of E & TC

  13. If the converter has a purely resistive load of R and the delay angle is , determine (a) the rectification efficiency (b) the form factor FF (c) the ripple factor RF and (d) the peak inverse voltage PIV of thyristor T1 Example: Prof. V. N. Bhonge Dept. of E & TC

  14. Solution: (a) the rectification efficiency Prof. V. N. Bhonge Dept. of E & TC

  15. (b) the form factor FF (c) the ripple factor RF (d) the peak inverse voltage PIV of thyristor T1 Prof. V. N. Bhonge Dept. of E & TC

  16. Example Design a circuit to produce an average voltage of 40V across 100 load resistor from a 120Vrms 60 Hz ac source. Determine the power absorbed by the resistor and the power factor. Briefly describe what happen if the circuit is replaced by diode to produce the same average output. Prof. V. N. Bhonge Dept. of E & TC

  17. Example (Cont)… Solution In such that to achieved 40V average voltage, the delay angle must be • If an uncontrolled diode is used, the average voltage would be • That means, some reducing average resistor to the design must be made. A series resistor or inductor could be added to an uncontrolled rectifier, while controlled rectifier has advantage of not altering the load or introducing the losses

  18. Controlled, Half-wave converter with R-L load Prof. V. N. Bhonge Dept. of E & TC

  19. The analysis of the circuit is very much similar to that of uncontrolled rectifier. Con…. Prof. V. N. Bhonge Dept. of E & TC

  20. Cont…. Prof. V. N. Bhonge Dept. of E & TC

  21. Controlledfull-waverectifiers with R Load Prof. V. N. Bhonge Dept. of E & TC

  22. Thepowerdeliveredtotheload Thermscurrentinsourceisthesameasthermscurrentin theload. Prof. V. N. Bhonge Dept. of E & TC

  23. Single-PhaseFull Converter with RL Load Rectification Mode Inversion Mode Prof. V. N. Bhonge Dept. of E & TC

  24. Operation : vs is positive is is positive power flows from vs to the load vs is negative is is positive power flows from load to vs Prof. V. N. Bhonge Dept. of E & TC

  25. 2-Quadrant Operation Prof. V. N. Bhonge Dept. of E & TC

  26. Cont… Prof. V. N. Bhonge Dept. of E & TC

  27. Single-Phase Full Converter (RL-load) Mode 1 = Mode 2 Prof. V. N. Bhonge Dept. of E & TC

  28. Single-Phase Full Converter (RL-load) RMS Current for Thyristor RMS Current for Thyristor RMS Output Current AVG Output Current Prof. V. N. Bhonge Dept. of E & TC

  29. ControlledSingle-phaseconverteroperatingasaninverter：. • Average value of vd is negative for 90o<a<180o. Average power Pdis negative (Pd=VdId) and thus power flows from the dc to the ac side • On the ac side, Pac=VsIs1cosf1 is also negative because f1>90o • Inverter mode of operation is possible because there is a source of energy on the dc side • ac side voltage source provides commutation of current from one pair of thyristors to the others Prof. V. N. Bhonge Dept. of E & TC

  30. Forinverteroperation, powerissuppliedbythedcsource, andpowerisabsorbedbythebridgeandistransferredtotheacsystem. VdcandVomustbenegative For …………rectifieroperation   ………inverteroperation Prof. V. N. Bhonge Dept. of E & TC

  31. Half Controlled Bridge (Semiconverter) a) Symmetrical b) Asymmetrical Prof. V. N. Bhonge Dept. of E & TC

  32. Average and RMS Value of output voltage Prof. V. N. Bhonge Dept. of E & TC

  33. Mode 1 Mode 2 Single-Phase Semiconverter (RL-load) Prof. V. N. Bhonge Dept. of E & TC

  34. RMS Current for Thyristor RMS Current for Thyristor RMS Output Current AVG Output Current Single-Phase Semiconverter (RL-load)

  35. The single-phase semiconverter has an RL load of L = 6.5mH, R = 2.5 Ohm, and E = 10 V. The input voltage is VS = 120 V(rms) at 60 Hz. Determine (a) the load current IL0 at , and the load current IL1 at , (b) the average thyristor current IA (c) the rms thyristor current IR (d) the rms output current Irms and (e) the average output current Idc Problem : Prof. V. N. Bhonge Dept. of E & TC

  36. 3 Phase Controlled Rectifiers • Operate from 3 phase ac supply voltage. • They provide higher dc output voltage. • Higher dc output power. • Higher output voltage ripple frequency. • Filtering requirements are simplified for smoothing out load voltage and load current. Prof. V. N. Bhonge Dept. of E & TC

  37. Extensively used in high power variable speed industrial dc drives. • Three single phase half-wave converters can be connected together to form a three phase half-wave converter. Prof. V. N. Bhonge Dept. of E & TC

  38. Vector Diagram of 3 Phase Supply Voltages Prof. V. N. Bhonge Dept. of E & TC

  39. Prof. V. N. Bhonge Dept. of E & TC

  40. Three-Phase Full Converter ECE 442 Power Electronics Prof. V. N. Bhonge Dept. of E & TC

  41. Waveforms: Prof. V. N. Bhonge Dept. of E & TC

  42. The line-to-neutral voltages are: • Then the line-to-line voltages are: Prof. V. N. Bhonge Dept. of E & TC

  43. The average output voltage is found from: • The rms value of the output voltage is: Prof. V. N. Bhonge Dept. of E & TC

  44. A three-phase bridge gives a six-pulse output voltage. • For high -power applications such as high-voltage dc transmission, a 12 pulse output is generally required to reduce the output ripples and to increase the ripple frequencies. • Two six-pulse bridges can be combined either in series or in parallel to produce a 12-pulse output. Prof. V. N. Bhonge Dept. of E & TC

  45. 3 Phase Half Controlled Bridge Converter (Semi Converter)with Highly Inductive Load & Continuous Ripple free Load Current Prof. V. N. Bhonge Dept. of E & TC

  46. Prof. V. N. Bhonge Dept. of E & TC

  47. Wave forms of 3 Phase Semiconverter for  > 600 Prof. V. N. Bhonge Dept. of E & TC

  48. Prof. V. N. Bhonge Dept. of E & TC

  49. Prof. V. N. Bhonge Dept. of E & TC

  50. Wave forms of 3 Phase Semiconverter for  600 Prof. V. N. Bhonge Dept. of E & TC

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