tostino wrote:So don't think no one cares what your doing.
Yeah.. been reading this thread since the beginning.
JCG wrote::lol: Thanks guys. Things can be lonely on the low energy, high power side of the tracks!
Quick note: I have hooked up a 36V DeWalt "Nano" battery pack in parallel with the capacitor.
The pictures inside the toolbox would be messy, but here's a circuit diagram:
The lamp keeps the charging current to around 3 A max when the switch is open - used when there is a big (initial) difference in the cap and battery voltages, like when the cap is dead and needs charging. Then, I can close the switch and allow fast charge transfer between the two when they are at about the same voltage.
I rode home and back with it like this, the resting voltage is about 33.2 V now, and on the way home I got it to 33.6. Not much swing! Motoring up a longer hill on the way in today called on about 25 A or so for most of the time, but the voltage had only dipped from 33.2 to about 31.9 when I waited at the stoplight at the top of the hill, and it slowly climbed back to 33.2 while I waited there. Interesting stuff - but needs data acquisition and graphs to be discussed properly!
tostino wrote:From the looks of it, just the addition of one battery will increase the usability of your system greatly. I can see the Dewalt providing enough current for a long enough period of time to extend your hybrid pedal/electric range MUCH further than previously, while also retaining the abilities of the bike to regen TONS of current, and not need to always be plugged in to be used.
JCG wrote:Interesting... and here I was thinking about tearing the cap box apart and removing a few of those to get it down to 36 V or so...
Maybe some kind of diode setup between parallel-connected battery (36V) and cap (up to 48 V) with the diodes preventing current going into the battery, but allowing it to come out if the cap voltage drops below 36V? Hmmm...
yanwin wrote:Can i ride it for 3 hours?
JCG wrote:The ride home (in the movies) has some fair downhills, so I expected a net recovery, but right now I don't even know the net elevation change... more work to do!
I put the laptop on my back and rode out to the running track to get some zero slope data. I took a bunch of things but here is the data of me trying to keep a steady 20 kph without any pedaling. Look closely and you can see when I was facing in to the wind around the oval-shaped track.
Regeneration: In industry commercial inverters are used to vary AC motor speeds by intentionally changing the frequency supplied to the motor. If you overspeed the motor, the motor is returning the power back to its power supply. When you use an inverter that has a variable frequency capability, you turn the frequency down and your motor is a generator, returning its power to the controller, until your new reduced speed is reached. Or you can have a over running load, like when you drive your AC motor powered tractor down a hill, and your motor is a generator.
Here is the problem in industry: Most AC inverters cannot return the excess power to the power line. There is a diode bridge that takes AC power and charges a capacitor bank. (There are a very few specialized AC inverters that use a bi-directional bridge of transistors to charge the capacitors or return power to the AC line.) With diodes that is strictly a one way trip. The capacitor bank is connected to the motor via a bridge of transistors or gate turn off SCRs. This bridge is bi-directional. So whenever the motor is a generator, the capacitor bank is charged up and potentially overcharged. Some drives turn off to protect the controller. Some drives switch on a resistor to dump the excess energy. Here we are not really regenerative, although the motor does not know any better.
If you were to replace the capacitor bank with batteries, like some electric cars, you now have the ability to absorb a lot of energy from the motor, and you can easily be regenerative over the entire speed range of the motor, whereas to regenerate with a DC motor you need to do tricks with field windings and still may not be regenerative over the entire speed range.
paultrafalgar wrote:Any news, JCG? Eagerly awaiting developments!
JCG wrote: I have been spending experimental time dealing with a 290 V, 27.5 F capacitor setup (6 modules in series) that is powering an AC motor and have been extracting regen from it by spinning up a cast iron pulley (flywheel) and then slowing it down. As for the bike...
europa81 wrote:Please the combination. I've enjoyed your experiment from the beginning and see a practical use of the Capacitor in efficiently buffering energy from braking to the next boost needed for acceleration.
liveforphysics wrote:Are you working on over-unity with that project? I love that stuff, and I've been a long time magnet motor tinkerer. Any neat photos?