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Research Activities in Power Electronics at UCF PowerPoint Presentation
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Research Activities in Power Electronics at UCF

Research Activities in Power Electronics at UCF

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Research Activities in Power Electronics at UCF

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  1. Research Activities in Power Electronics at UCF Presentation at Princess Sumaya University for Technology Florida Power Electronics Center Orlando, Florida USA

  2. Outline of topics • About Florida Power Electronics Center • Single-Stage PFC Converters • Low Voltage DC-DC converters • Inverters • Generalized Analysis of DC-DC • Converters

  3. WELCOME TO FLORIDA Orlando Area

  4. FloridaPower Electronics Center Dr.Issa Batarseh – Director Dr.Wenkai Wu – Asst Director Power Factor Correction (PFC) Circuits - NASA Soft-Switching DC-DC Converters - I-4 Florida Initiative Low voltage AC-DC and DC-DC Converters - NSF Dynamic Modeling and Control - NSF Electromagnetic Interference and Compatibility - NSF Inverter Application / Photovoltaic Cell – Industry & I-4 High Frequency AC DPS – NSF & I-4 Maximum Power Point Tracking System Smart Electronic Load

  5. Multidisciplinary Research Group Topologies and Converter System Dr. Issa Batarseh Magnetics Dr. Thomas Wu Power Devices Dr.J J Liou Modeling and Control Dr.Zhihua Qu Packaging Dr.Louis Chow

  6. FloridaPEC - Team Peter Kornetzky Shiguo Luo Joy Mazumdar Wenkai Wu Khalid Rustom Wei Gu Duy Bui Wei Hong Shailesh Anthony Jia Luo Songqrian Deng Christopher Iannello Abdelhalim M Alsharqawi JaberA.Abu Qahouq Jay Vaidya Shilba Reedy

  7. Power Conversion TV sets Medical equipment AC/DC converter power supply Telecommunication device, and other industrial equipment Computer ~ Converter AC Source DC Load

  8. Single-Stage PFC Converters

  9. Definition of Power Factor For linear load: For nonlinear load :

  10. Special Case --Distortion factor, where --Displacement factor

  11. Typical Line Current Waveform Without PFC Line current is zero when vl(t) < vc(t). PF  0.67 THD >110%

  12. PFC Approaches i) Passive PFC converter ii) Active two-stage PFC converter iii) Active single-stage PFC converter

  13. Three Basic PFC Approaches Passive PFC converter Active two stage PFC converter Active single stage PFC converter

  14. Special Family--Single-stage PFC AC/DC Converter PFC stage and DC/DC stage share the same switch Single Loop

  15. Prior Art Advantage Simple Least component count Disadvantage Inherent Low efficiency High DC Bus Voltage Stress Turn off spike (a) Boost/flyback combination DCM+DCM (Redl, 1994) Advantage No turn off spike Low voltage rated capacitor Disadvantage Inherent Low efficiency High DC Bus Voltage Stress (b) Boost/forward combination DCM+DCM (Russian circuit, 1992)

  16. Rough DC power 1 DC/DC cell eff. 2 Final DC output power 12 PFC cell eff. 1 Ac input Conventional Energy transfer concept

  17. Direct transferpower (1-k)1 1-k DC/DC cell eff. 2 DC output power k12 +(1-k) 1 DC power k1 PFC cell eff. 1 Ac input k New energy transfer concept k12+(1-k) 1>12

  18. New Concept • Flyboost PFC cell + Flyback DC/DC cell • Single active switch + single controller

  19. Operation mode • Flyback mode: |Vin| < Vcs – n1 * Vo • Boost mode: |Vin| > Vcs – n1 * Vo

  20. Simulation results Operation waveform in one line cycle Trace 1 Current through flyback winding Trace 2 Rectified input current Trace 3 DC/DC stage current

  21. Apply to other topologies

  22. Experimental Results • Measured Power Factor vs. line voltage • Measured Efficiency vs. line voltage • Measured storage capacitor voltage (Vs) vs. line voltage • Line voltage and line current at line voltage=110V AC. Trace A: Line voltage (100V/div, 5ms/div); Trace B: Line current (measured after auxiliary line filter;1A/div; 5ms/div). The measured Power Factor is 99.4%

  23. Special application Bi-Flyback Converter • Inegrate Bifred and Flyboost topologies • Two flyback transformers, single switch • Single DC bus capacitor

  24. Soft switching application

  25. Developed prototype

  26. Waveforms Line Voltage Input voltage: 110V Output watts 150W Line Current Line Voltage Input voltage: 220V Output watts 150W Line Current

  27. Waveforms for the main switch Vds Id

  28. Efficiency and Power Factor 200KHz/28V@5.35A

  29. Improved Results

  30. Key Features • Higher efficiency due to soft switching operation of the main switch. • Low DC bus voltage make commercially available capacitor can be used as the energy storage part • Higher efficiency due to direct energy transfer in Flyback mode • Higher power density due to high frequency operation, which also benefit from soft switching

  31. Powering Future Generation of Microprocessors and ICsLow-Voltage High-Current Fast-Transient On-Board Voltage Regulator Modules(VRMs)

  32. Structure

  33. The Main Power Supply Requirements(Challenges) • 1. High output current slew rate (> 50A/s). • 2. Low output voltage ripple and overshoot during transient (< 2% of the nominal output voltage). • 3. High efficiency • 4. High power density. • 5. High VRM input current slew rate (<0.1A/s). • 6. Packaging, thermal design, and EMC.

  34. Pentium 4Voltage and Current Specs

  35. Current and Voltage Roadmap Year1999200020012002200320042005 Vmax 1.8 1.8 1.5 1.5 1.5 1.2 1.2 Vmin 1.5 1.5 1.2 1.2 1.2 0.9 0.9 W 90 100 115 130 140 150 160 Imin(A) 50 56 77 87 93 125 133 Imax(A) 60 67 96 108 117 167 178 Lately, there are news about even lower voltages and higher currents expectations in the future (APEC’2001, March 2001)

  36. Interleaving Technique for Multi-phase Converters

  37. Why Voltage-Mode Hysteretic Control and Interleave Technique? Effective &simple to apply The Voltage-Mode Hysteretic Control Tracks the output voltage (ripple) and keeps it within the required limits. Near instantaneous response to load transients. No feedback loop compensation is needed. No limitations on the switches conduction time Circuit simplicity • The Interleave Technique • High frequency output voltage ripple with lower switching frequency • Ripple cancellation • Current division between the phases • Fast transient response which is limited by the feedback control loop +

  38. Initial Experimental PrototypeWaveformsPreliminary Results Phase 1 Drive Signal Input Voltage =12V Output Voltage =1.5V Output Current =30A Switching Frequency/Phase =400KHz Output Ripple Frequency =800KHz Phase 2 Drive Signal Phase 1 Inductor Current Phase 2 Inductor Current Total Current Output Voltage

  39. Initial Experimental Results Three-Phase VRM Control Two-Phase VRM Control Four-Phase VRM Control

  40. Transient Cancellation Control Method for Future Generation of Microprocessors The idea of the transient cancellation control scheme is to create a deliberate undershoot before an expected overshoot and vice versa to cancel the expected large overshoot to keep the output voltage within the allowable output voltage deviation limit. Ideal Output-Voltage Waveforms at High-to-Low Load Transient without the Transient Cancellation Controller Ideal Output-Voltage Waveforms at High-to-Low Load Transient with the Transient Cancellation Controller

  41. Future Look on VRMs and their Control Methods • To satisfy future strict powering requirements of microprocessors especially the tight allowable voltage deviation (20mV), may have to be one or more of the following: • 1) Proactive instead of reactive, i.e, to be able to take a response action before the load transients occur instead of after. • 2) Future VRM controllers may need to be able to ‘learn’ the load behavior and/or apply advanced response techniques to reduce the VRM output voltage overshoots/undershoots and to have fast transient response. • 3) Methods such as fuzzy logic and neural networks may be applied to make the VRM controller ‘smart’. • 4) Advanced Topology techniques that have naturally the voltage deviation reduction (cancellation)

  42. Generalized Analysis of Soft-Switching DC-DC Converters

  43. Conventional DC-DC Converters(Hard-Switching) Boost Buck Buck-Boost Cuk Zeta Sepic

  44. Switching-Cell Sharing All the Conventional DC-DC Converters shares the same switching-cell With different orientation of the cell in a specific converter The Conventional DC-DC Switching-Cell

  45. Analyzed Soft-Switching Cells

  46. Zero-Voltage-Switching Quasi-Resonant ZVS-QRC Switching-Cell ZVS-QRC Cell Basic Switching-Waveforms

  47. Zero-Voltage-Transition PWM ZVT-PWM Switching-Cell ZCT-PWM Cell Basic Switching-Waveforms

  48. ZVT-PWM Family ZVT-PWM Buck ZVT-PWM Boost ZCT-PWM Buck-Boost ZCT-PWM Cuk ZVT-PWM Zeta ZVT-PWM Sepic

  49. The Generalized Transformation Table Single Generalized Transformation Table is complete and applies to all cells

  50. Generalized Gain Equation Generalized gain ( ): By using the normalized parameters: