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

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

3. Power Electronics Chapter 3 Uncontrolled Rectifiers Un controlled Rectifiers Single-Phase Rectifiers Three-Phase rectifiers Half-WaveFull-Wave

4. A: s1_1 Power Electronics Chapter 3 : A Single –Phase Uncontrolled Rectifiers Single-Phase Rectifiers Half-Wave “HW” Full Wave “FW” Bridge circuitCenter tape

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

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. Conclusion : 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. PIV Vout Ic V diode

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 : In every commutation interval, two diodes operate together for angle  Which called overlapping angle. III- Three Phase Rectifier with failed diode The output voltage The load current The load currents The load voltage The diode voltage

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

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. Conclusion : 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.

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

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

12. Single Phase Half-Wave Circuit Supply voltage Output voltage Without C Output voltage With C Load current with C Conclusion : 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.

13. Single phase Uncontrolled Bridge rectifiers 1-Electrical circuit without filtering capacitor 1-Electrical circuit with filtering capacitor Conclusion : 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.

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

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

16. Single-Phase Rectifier – Center Tap Conclusion : 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

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

18. Additional Circuits Without stabilizer With stabilizer

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

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