Group Actions
Engagement
  • Author Author: corbin.sl
  • Date Created: Date Created
  • Views 570 views
  • Likes 1 like
  • Comments 4 comments
Related
Recommended

A little bit of wireless power research and a word to other contestants

corbin.sl

Hows it going everyone, I am Shane Corbin.  I am one of the lucky contestants, and I am very excited to to begin.  I am planning on integrating the BQ Tesla wireless power devices, along with a few TI goodies, into a robot that my 7yr old son and I are building.  I have received the wireless power kit and am quite impressed.  I have played with it a bit, and done a little testing, and here's what i've found so far.  The transmitter/receiver seems to be able to continue transmitting power up to at least 10mm. I plan to create some kind of rig to suspend the receiver over the transmitter and do some more exact testing, but while the voltage seems to stay pretty constant right up to the cutoff point, the current seems to taper off to around 50% of the rated output.  Mind you this is using a 5.6ohm resistor for a load and not a 5ohm which would draw the rated output power.  The current through the resistor was around 890mA.  And (very roughly) at a little more than 10 mm gap the output current tapered and cutoff at around 500mA.  Also note my meter is only acurate to +/-5mA tho I think that's a rather negligible amount in this case. 

 

image

In the picture above: power supply left guage is current into the transmitter and right guage is voltage into the transmitter.

The multimeter is current through the 5.6ohm load resistor connected to the output of the receiver.  The oscilliscope which

will be shown below and shows voltage at the output of the receiver.

 

image

This is the voltage output of the receiver with a 5.6ohm load.  Its magnified to a 500mV/div to show voltage ripple.

At 4.91V it has about a 580mV pk-pk ripple or about +/-290mV.  Not bad in my opinion and shouldn't be too hard

to deal with in my design.

 

Hope this is of interest to others and as I said I will try to get some more precise data on gap/voltage/current relationship.

 

 

To close I would just like to say good luck to all the other contestants.  My favorite part of the electronics field is getting to learn something new on a regular basis, and I hope to learn something from this experience and all of you as well.

 

Shane Corbin

Parents

  • I can't speak for others, but I certainly like learning new things all the time.

    You never know when a new bit of information can lead to an epiphany on a problem area.

     

    So post away.  I at least will be here to read and assess what you learn.

     

    By the way, have you isolated the cause of the ripple?

    Also, the inductive coupling should follow a curve at the square of the distance.  As you get further away from the coil, you should see a pretty rapid drop off.

     

    Thanks,

    DAB

  • in reply to DAB

    I haven't had a chance to isolate the source of the ripple.  The load resistor I am using is only rated at 2w and im pushing somewhere around 4 to 4.5w, so I had to make my measurements with a slight bit of haste.  I have a 30ohm load resistor but I am not sure that the load is gonna be significant enough to produce realistic results as I will be pulling pretty close to the rated wattage in the design.  I will keep you updated on what I find.

Comment
  • in reply to DAB

    I haven't had a chance to isolate the source of the ripple.  The load resistor I am using is only rated at 2w and im pushing somewhere around 4 to 4.5w, so I had to make my measurements with a slight bit of haste.  I have a 30ohm load resistor but I am not sure that the load is gonna be significant enough to produce realistic results as I will be pulling pretty close to the rated wattage in the design.  I will keep you updated on what I find.

Children
No Data