1 / 28

Wireless Power Transmission

Wireless Power Transmission. ECE 445: Senior Design Fall 2008 Project 7 Carl Westerby and Derek Runge. Purpose: Wirelessly transmit power from outlet to portable devices in a conference room Benefits Eliminates power cords going to the table (safety hazard)

cicily
Download Presentation

Wireless Power Transmission

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Wireless Power Transmission ECE 445: Senior Design Fall 2008 Project 7 Carl Westerby and Derek Runge

  2. Purpose: Wirelessly transmit power from outlet to portable devices in a conference room Benefits Eliminates power cords going to the table (safety hazard) A step towards portable devices that do not need to plug into the wall to charge Eliminates necessity of power bricks due to DC output Introduction

  3. Features • Provides steady DC output voltages for laptop and cell phone • Designed to operate off of a wall outlet for ease of installation • Coils can be hidden in the ceiling and under a table for aesthetics • Automated frequency tuning to adjust for different table to ceiling heights and room environments

  4. System Block Diagram

  5. Wall Voltage to DC Source

  6. Challenges and Solutions • Challenges • Filtering 60Hz can be difficult with small voltage and current ripple • 170V and 1A are relatively high voltage and current requirements • Solutions • Large capacitances and inductances used to help decrease voltage and current ripple • Special 200V capacitors were ordered from DigiKey and an inductor was wound with 20AWG wire

  7. Performance at 50W output

  8. Current Sensing Circuit

  9. Challenges and Solutions • Challenges • High common mode voltage for an Op-Amp • High input voltage requirements • Finding resistors that would give a gain to make the output range from 0 to approximately 5V • Solutions • Many circuits found online to overcome common mode problems using a zener diode and p-type transistors • High voltage current sensing Op-amp ordered from Linear Technologies • Calculations followed by trial and error iterations

  10. Efficiency Table/Graph

  11. PIC Microcontroller, DAC, and VCO

  12. Challenges and Solutions • Challenges • PIC PWM module is not fast enough for our purposes and the frequency is not variable once set • Parallel DACs with voltage output are hard to find • RNG pin and capacitance for VCO have large influence on min and max frequency of the VCO • Solutions • Digital output pins used to output a 10 bit parallel data word • Dan Block helped us find a DAC that would work for our needs • Many trial and error iterations before finding a good match

  13. Performance VCO Output at 3.308 MHz

  14. Gate Drivers and H-Bridge Inverter

  15. Challenges and Solutions • Challenges • Finding devices with specified current and voltage blocking ratings that can switch fast enough • Soldering the n-type transistors to anything • Voltage source isolation • Solutions • Asking professor Krein about fast MOSFETs and gate drivers • Creating a PCB and learning to use the reflow oven • Potential solutions for isolation are transformer, bootstrap capacitors, multiple supplies, PICs, DACs, VCOs and drivers

  16. Performance

  17. Coils • 100 turns, 20AWG wire, 1m diameter • Top Coil • Inductance: 28.85 mH • Series Resistance: 12.5Ω • Bottom Coil • Inductance: 28.15 mH • Series Resistance: 11.25Ω

  18. Coil Safety *See Reference 1 Based on a resonant frequency of around 4MHz our power density falls far below the safety limit of 180/f2.

  19. Challenges and Solutions • Challenges • Making sure that the coils could handle the current pulled through them • Winding the coils • Testing the coils • High impedance of the coils at a high frequency • Solutions • Finding the ratings for the American Wire Gauge standards • Breaking our backs and ruining our knees forever • Using a waveform generator • Use our finished circuit on

  20. Performance

  21. Rectifier and Filter

  22. Problems and Solutions • Problems • Finding a fast enough diode • Solutions • Increase current through diode • Use Schottky Diodes for faster response

  23. Performance of Filter

  24. Buck Converter

  25. Problems and Solutions • Problems • Low efficiencies • Low Output Powers • Solutions • Add a heat sink • Find a converter that can handle more current or build our own

  26. Performance 6.2Ω was not at 5V (3V)

  27. Conclusion • It is much harder to transmit power wirelessly than it originally seemed • Working at high frequencies and relatively high power makes finding parts quite a task • When you’re stuck, ask someone! People are almost always willing to help. • Someday wireless power may be an industry standard and you will not have to plug in portable devices ever again

  28. Reference 1. Dorf, Richard C. Sensors, Nanoscience, Biomedical Engineering, and Instruments. http://books.google.com/books?id=mYDxYh6ZtJAC&pg= PT287&lpg=PT287&dq=IEEE+C95.6&source=bl&ots=_S kvk7arve&sig=mrFiM4EcGPjxTnVpIa9xf6y- kUQ#PPT175,M1. CRC Press: 2006.

More Related