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PALESTINE POLYTECHNIC UNIVERSITY (PPU) POWER ELECTRONICS Dr. Sameer Khader Spring

PALESTINE POLYTECHNIC UNIVERSITY (PPU) POWER ELECTRONICS Dr. Sameer Khader Spring 2003 / 2004 2005/2006. Rectifier Classification. Chapter 3-A : Single Phase Rectifiers. Chapter 3-B Three-Phase Rectifiers. Power Electronics Chapter 3 Uncontrolled Rectifiers. Un controlled

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PALESTINE POLYTECHNIC UNIVERSITY (PPU) POWER ELECTRONICS Dr. Sameer Khader Spring

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  1. PALESTINE POLYTECHNIC UNIVERSITY (PPU) POWER ELECTRONICS Dr. Sameer Khader Spring 2003 / 2004 2005/2006

  2. Rectifier Classification Chapter 3-A : Single Phase Rectifiers Chapter 3-B Three-Phase Rectifiers

  3. Power Electronics Chapter 3 Uncontrolled Rectifiers Un controlled Rectifiers Single-Phase Rectifiers Three-Phase rectifiers (1F) Half-Wave Full-Wave (3F-Half) (3F-Full)

  4. Power Electronics Chapter 3 : A Single –Phase Uncontrolled Rectifiers Single-Phase Rectifiers Half-Wave “HW” Full Wave “FW” A: s1_1 (HF) Bridge circuit Center tape (FW) (FW-C)

  5. Power Electronics Chapter 3 : B Three –Phase Uncontrolled Rectifiers Three-Phase Rectifiers Half-Wave “HW” Full Wave “FW” A: s1_1 (1F-Half) (1F-Full)

  6. Three-Phase Half Wave Uncontrolled I- With Resistive Load Principle of operation : 1-Each diode must conduct for 120 dg while the anode voltage is maximum positive comparing with the other anode voltages . 2- Each phase voltage is connect to the load for the time of 120 dg. 3-The source ( phase) current is unsymmetrical because it’s flow only during the positive half cycles . Ic Conclusion : (Math equations) 1- Low ripples , comparing with single-phase rectifier 2- Relatively acceptable efficiency and TUF 74 % 3-There is a dc component in the source current (heavy saturated transformer) 4- The output ripples are three-times the supply frequency . 5- The diode inverse voltage is 1.731 Vm . Vout Vdiode PIV (R-L load) (D1 faield)

  7. II- Three Phase Rectifier with R-L Load The existing of inductance in the rectification circuit ( supply transformer & load inductance), leads to: 1- Voltage reduction in the average output voltage; 2- Current deformation of the output & phase current 3- Increasing the harmonic specter, therefore , increasing the harmonic losses . The output voltage : The load current In every commutation interval, two diodes operate together for angle  Which called overlapping angle . The load currents III- Three Phase Rectifier with failed diode The load voltage The diode voltage The output voltage

  8. The mathematical equations of HW – Three Phase Rectifier 6 - The source current: 1- The average voltage & current : 2- The RMS voltage & current: 7 - The diode average current : 8 - The diode rms current : 3 - The output average & AC power: 4 - The rectification efficiency: 7 - The Form factor : 8- The Ripple Factor : 5- The transformer utility factor: . 9- Diode PIV : where

  9. Three-Phase Full Wave Uncontrolled I- With Resistive Load Principle of operation : 1-Each diode from anode group will conduct for 120 dg while the anode voltage is maximum positive comparing with the other anode voltages . And one diode from cathode group also conduct for 120 dg, while the cathode voltage is maximum negative . 2- Each diodes group is connect to the load for a time of 60 dg. 3-The source ( phase) current is symmetrical, therefore no saturation effect 4- the supply voltage connected to the load is line voltage . 1- Low ripples , comparing with another circuits (4% ripples), therefore no need of filter 2- Extremely high efficiency efficiency and TUF > 96% 3-There is no dc component in the source current , therefore minimized losses 4- The output ripples are with six-times the supply frequency . 5- The diode inverse voltage is 1.731 Vm . 6- the phase rms current is 81% of the load rms value . 7- This circuit find widespread applications in wide range of the power specter . Conclusion : (Math equations) (R-L load)

  10. II- FW Rectifier with R-L load Load current Output voltage Phase current Phase current The output average voltage:

  11. Mathematical Modeling of FW – Three Phase Rectifier 6 - The source current: 1- The average voltage & current : 2- The RMS voltage & current: 7 - The diode average current : 8 - The diode rms current : 3 - The output average & AC power: 4 - The rectification efficiency: 7 - The Form factor : 5- The transformer utility factor: . 9- The Ripple Factor : 10- Diode PIV : where

  12. Single Phase Half-Wave Circuit Supply voltage Output voltage Without C (Math equations) Conclusion : Output voltage With C 1- High ripples , therefore large value of capacitor is required 2- Poor efficiency and TUF ~28%--31% 3- Dc component in the source current ( heavy saturated transformer ) 4- The output ripples have the same frequency equals the source frequency . Load current with C

  13. Single phase Uncontrolled Bridge rectifiers 1-Electrical circuit without filtering capacitor 1-Electrical circuit with filtering capacitor (Math equations) 1- Low ripples , therefore small value of capacitor is required 2- Relatively high efficiency and TUF 81 % 3- No dc component in the source current ( no-saturation Effect in the transformer 4- The output ripples have twice frequency with respect to the source . Conclusion :

  14. The mathematical equations of FW Bridge Rectifier - The transformer utility factor: 1- The main parameters : * rectification output parameters : - Average output voltage & current: where - for FW- bridge….. - for FW- center tape - The RMS voltage: - The ripple factor: - The harmonic factor - The output average & AC power: ; HF= 1.11 - The rectification efficiency:

  15. The mathematical equations of HW Rectifier - The transformer utility factor: 1- The main parameters : * rectification output parameters : - Average output voltage & current: where apparent power source current - The RMS voltage: - The form factor : ; FF= 1.57 - The ripple factor: - The harmonic factor - The output average & AC power: - The rectification efficiency:

  16. Single-Phase Rectifier – Center Tap Conclusion : (Math equations) 1- Low ripples , therefore small value of capacitor is required 2- Relatively high efficiency and low TUF ~ 57% 3- No dc component in the source current ( no-saturation Effect in the transformer 4- The output ripples have twice frequency with respect to the source . 5- The diode PIV voltage is twice the supply voltage (Additional Circuits)

  17. Mathematical Equations of FW Rectifier – Center Tap - The transformer utility factor: 1- The main parameters : * rectification output parameters : - Average output voltage & current: where - for FW- center tape - The form factor : - The RMS voltage: ; FF= 1.11 - The ripple factor: - The harmonic factor - The output average & AC power: - The rectification efficiency:

  18. Additional Circuits Without stabilizer With stabilizer

  19. Thyristor and Triac Circuits Load Triac voltage Thyristor voltage 150.0 V 200.0 V A: scr1_1 A: r2_2 50.00 V 100.0 V -50.00 V 0.000 V -150.0 V -100.0 V Triac current -250.0 V 20.00ms 35.00ms 50.00ms 65.00ms -200.0 V 35.00ms 50.00ms 65.00ms 80.00ms Load curent 2.250 A A: r2[i] 2.500 A A: r2[i] 1.750 A 1.500 A 1.250 A 0.500 A 0.750 A -0.500 A Capacitor voltage 0.250 A -1.500 A -0.250 A -2.500 A 20.00ms 35.00ms 50.00ms 65.00ms 35.00ms 50.00ms 65.00ms 80.00ms Capacitor voltage 2.500 V A: r1_2 1.500 V A: d1_k -2.500 V 0.500 V -7.500 V -0.500 V -12.50 V 40.00ms 55.00ms 70.00ms 85.00ms -1.500 V 35.00ms 50.00ms 65.00ms 80.00ms

  20. Triac firing circuits UJT needles 5.000 V A: q1_3 3.000 V 1.000 V -1.000 V -3.000 V -5.000 V 6.000ms 8.000ms 10.00ms 12.00ms Load voltage 12.50 V A: q1_2 7.500 V 2.500 V -2.500 V -7.500 V -12.50 V 5.000ms 15.00ms 25.00ms 35.00ms . Pulse generator 12.50 V A: q1_3 Capacitor voltage 7.500 V 2.500 V -2.500 V -7.500 V 25.00 V -12.50 V Load voltage A: c1_2 0.000ms 10.00ms 20.00ms 30.00ms 15.00 V 5.000 V 12.50 V -5.000 V A: q1_2 7.500 V -15.00 V 2.500 V -25.00 V -2.500 V 0.000ms 5.000ms 10.00ms 15.00ms -7.500 V -12.50 V 0.000ms 10.00ms 20.00ms 30.00ms

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