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A Low Output Ripple DC to DC converter topology using voltage overlapping technique

Power e Lab HKU. Prepared by Franki Poon www.eee.hku.hk/power_electronics_lab/ 1. A Low Output Ripple DC to DC converter topology using voltage overlapping technique. The Power Electronics Lab., Hong Kong University C. P. Liu N. K. Poon M. H. Pong Speaker C.P.Liu.

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A Low Output Ripple DC to DC converter topology using voltage overlapping technique

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  1. PowereLabHKU Prepared by Franki Poon www.eee.hku.hk/power_electronics_lab/ 1 A Low Output Ripple DC to DC converter topology using voltage overlapping technique The Power Electronics Lab., Hong Kong University C. P. Liu N. K. Poon M. H. Pong Speaker C.P.Liu

  2. PowereLabHKU Ipp L=300nH f1x f1x L=300nH Prepared by Franki Poon www.eee.hku.hk/power_electronics_lab/ 2 Low output ripple solutions – Interleaving Input voltage = 36V Duty cycle = 0.5 Ripple current p-p = 0A !!

  3. Low output ripple solutions – Interleaving PowereLabHKU Ipp L=300nH f1x f1x L=300nH Prepared by Franki Poon www.eee.hku.hk/power_electronics_lab/ 3 Input voltage = 72V Duty cycle = 0.25 Ripple current p-p = 20.833A ??

  4. PowereLabHKU L Ipp f1x L f1x Prepared by Franki Poon www.eee.hku.hk/power_electronics_lab/ 4 Low output ripple solutions – Interleaving Ripple current vs. Input voltage

  5. PowereLabHKU Prepared by Franki Poon www.eee.hku.hk/power_electronics_lab/ 5 Low output ripple solutions – Single phase Ipp f2x L = 266nH Interleave converter Even better than Multi-phase Single phase converter Question: Why 266nH and freq = 2 x f ?

  6. PowereLabHKU Ae Ae Prepared by Franki Poon www.eee.hku.hk/power_electronics_lab/ 6 One inductor reduces resistance 2 1 1 1 Ae Ae 2(1+1+1+1)=8 (1+2+1+2)=6 For same copper loss: N = 4/3 N = 1 For same flux density: L = (16/9 x 300/2) nH L = 300nH

  7. PowereLabHKU Prepared by Franki Poon www.eee.hku.hk/power_electronics_lab/ 7 Ultimate interleaving – 50%+50%  =12

  8. PowereLabHKU Prepared by Franki Poon www.eee.hku.hk/power_electronics_lab/ 8 What if more than 50% ? Vp Vp Vp Pure DC from AC pulse

  9. PowereLabHKU Vp Vp Vp Prepared by Franki Poon www.eee.hku.hk/power_electronics_lab/ 9 No regulation - stupid! Vp Vp Vp Need Amplitude Modulation

  10. PowereLabHKU D D Prepared by Franki Poon www.eee.hku.hk/power_electronics_lab/ 10 Simplest Amplitude Modulator Vp Vp(1-D) Vp Vp(1-D)

  11. PowereLabHKU Va Vo Vb Prepared by Franki Poon www.eee.hku.hk/power_electronics_lab/ 11 World’s first wide range & wide loading output capacitorless DCDC regulator. Va Vb Stupid again! Vo

  12. PowereLabHKU Prepared by Franki Poon www.eee.hku.hk/power_electronics_lab/ 12 World’s first wide stupid DCDC regulator. More components than a already good interleaving converter ! !

  13. PowereLabHKU Prepared by Franki Poon www.eee.hku.hk/power_electronics_lab/ 13 Isolated Overlap VS Isolated Interleave Compare with the more complicated approach

  14. PowereLabHKU Prepared by Franki Poon www.eee.hku.hk/power_electronics_lab/ 14 No perfect DC blocking capacitor Va Va Vb Vb Vo Ripple voltage introduced

  15. PowereLabHKU Va Vb Prepared by Franki Poon www.eee.hku.hk/power_electronics_lab/ 15 Of course an O/P capacitor is needed Vo ICo Resonate current pulse

  16. PowereLabHKU Prepared by Franki Poon www.eee.hku.hk/power_electronics_lab/ 16 Final configuration – add a current source Ls << Lo Va Ls1 Lo Vb ILs1 Ls2 ILs2

  17. PowereLabHKU Va Ls1 Vb Ls2 ILs1 ILs2 Prepared by Franki Poon www.eee.hku.hk/power_electronics_lab/ 17 Overlapping + Sync-Rect Circulating current, becareful.

  18. PowereLabHKU O/P Inductor current 50 nH 0.33 uF 300 nH 100 uF O/P diodes current Gate drive Gate drive 0.33 uF 50 nH 2.5V@15A Efficiency = 88% O/P ripple = 50mV fs = 200kHz Prepared by Franki Poon www.eee.hku.hk/power_electronics_lab/ 18 Overlapping + Active Diode 36V-72V

  19. PowereLabHKU Prepared by Franki Poon www.eee.hku.hk/power_electronics_lab/ 19 Overlapping or Interleaving 2A p-p 20.8A p-p Same O/P Inductor Same 72V I/P voltage Same D=0.5 at 36V I/P 300 nH 300 nH 300 nH

  20. PowereLabHKU Prepared by Franki Poon www.eee.hku.hk/power_electronics_lab/ 20 After all . . . • Good reasons to look for more low output ripple configurations • A simple configuration producing very low output ripple current is proposed • ZVS of primary switches is possible • Output ripple is independent on input voltage • Low stress on MOSFET • Good for low voltage high current applications

  21. Intermediate bus in 48V system 2.8 x 4.5 inches2 500W output 14V, 36A with tight regulation PowereLabHKU Prepared by Franki Poon www.eee.hku.hk/power_electronics_lab/ 21 Potential application

  22. PowereLabHKU Prepared by Franki Poon www.eee.hku.hk/power_electronics_lab/ 22 Thank you

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