I'm experimenting with the flywheel and have a problem. Instead of tapping stored energy from the flywheel intermittently (charge - discharge, charge - discharge), I want to maintain the charge under load by using a motor and a generator instead of the conventional motor/generator. I need a motor control circuit that senses the rotational speed of the flywheel (inductive pickup, reed switch,??) and, when neccessary, energizes the motor to keep it spinning at a preset velocity (approx. 900rpm).
I have no problem with the mechanics of it. Any guidance will be appreciated.
I was under the impression that the system had been realized. I've read NASA pages on the web claiming that friction losses could be reduced by using magnetic bearings. I'm not exactly sure what that means but, I believe it is an attempt to suspend or levitate the shaft in the bearings...lots of luck.
That stuff is way over my head. I'm thinking in simpler terms. The flywheel in my design is just a mechanical assist to the generator. When I was a kid, some of the wind up toys were powered by a spring and a flywheel. Energy cranked into the spring was transfered to the flywheel/gear which powered the toy. The flywheel also added a degree of stability like a Gyro. An object in motion wants to stay in motion. My flywheel is used to assist this and hopefully add stability in maintaining a constant frequency of 60hz (+ - 0) @ 900rpm for an 8 pole genny. That's where the circuitry comes into play by monitoring and maintaining the speed of the flywheel.
I realize there may be some fine points of the law that I haven't taken into account but, I haven't made it that far yet.
The energy stored in a flywheel is proportional to its speed. If you declare the flywheel shall run at constant speed then you are also declaring the flywheel energy shall be constant.
To maintain constant energy you must put in exactly what you take out. The actual amount of energy stored in the flywheel becomes irrelevant so you may as well make it really small, such flywheels are more commonly known as shafts.
I am a welder by trade. I've built this genny from fab shop scrap, magnets scrounged from discarded magnetrons, bearings from ebay and a hardened precision shaft from McMaster-Carr. The flywheel I mentioned was laser cut from 3/8" steel plate and doubles as the rotor to which the magnetron magnets are mounted. I chose the heavy rotor thinking that it would help to counter reactance when a load was placed on the genny but, having read your post, I realize now that I may have been thinking wrong. The circuit I need would have to sense the reduction in frequency and speed up the motor to compensate as well as sense an increase in frequency and slow the motor down. Holding to 60hz is my main concern.
I've started to look at the PIC's but, it's going to take a little time to learn the code well enough to program.
To store a lot of energy in the flywheel, it needs to spin really fast. Like 10000s of RPM. So it needs to be in a vacuum chamber to reduce drag, and it needs to be real stong to keep from flying apart. There is an optimal aspect ratio for the thing... it cant be too wide or the centrifugal force is too great, cant bee too skinny or it doesnt have enough rotational inertia to store the energy. I guess you already know about the NASA magnetic bearings from outer space. Those are probably real expensive. KE=1/2 x M x V^2
It would help if you said what you were really trying to do. A flywheel isn't going to buy you much unless you have loads with high peaks and you accept that the frequency will drop some as energy is taken from the flywheel to meet those peaks.
If you have 60Hz ac in and want 60Hz ac out then use a transformer. Motor generator sets are generally only used when you want to change frequency.
You haven't said anything about what motor you have or are thinking of or about what kind of power you are talking about. Many motor applications require the motor to run at approximately constant speed. The more precise the speed and the more variable the load the harder it gets.
Well, actually, this part is fairly common - they do levitate, but there's still friction, albeit very much less than mechanical bearings.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
It's not like legislation - it's more like "the law of conservation of momentum" or something like that, in the same class as "the law of gravity" and so on. :-)
I was making a joke before, because what you're describing is perpetual motion.
I've went this far, I may as well fill the bucket and brace for impact.
I came up with this Idea during the 4 hurricane hits in Florida a few years ago. During that time, there was no power, period. We barely had food and water. People were literally fighting at the pumps over the last few drops of gasoline. So much for gas driven gennies. We lost all perishable foods from the fridge and freezers. The only powered device that remained was a battery operated transistor radio. That's when the Idea crossed my mind....what about a battery operated generator, not so much as to power the entire residence but, to keep certain neccessities going for as long as possible. I remember one guy that had a chest freezer full of meat. After it thawed, he smoked all of it and passed it out to anyone that came by.
I brought the Idea to the group back then and was severely bashed stating that all it would be was an expensive battery discharger. Granted, that it will be but, it could make the difference in an emergency situation.
I believe Jasen said, "you get out what you put in!", an hour, several hours...a day. I don't know, haven't completed the prototype yet. The dc motor I have at present draws 10 amps, too much for a frugal application. I added the flywheel in the mix thinking that once I got the rotor up to operating speed, there would be enough inertia that the motor would not have to labor as hard trying to maintain op speed and I could use a smaller motor drawing less amperage.
We have battery operated everythings in this time. An uninterrupterable power supply is a stab in the same direction. I would not be suprized to find that someone has already built something similar and I just haven't run across it yet.
I don't see how it would be looked at as getting something for nothing. It would transform stored dc into ac to be used in a period of time, until the battery dies or is replaced.
You can't get any more energy out than you've put in, period. For battery backup, the most efficient way is to run your stuff right off the batteries. Maybe an inverter, but you will not ever get any more energy out of the system than you put into it - that's just the way this 4-D slice of the Universe works today.
Use a big freezer and fill up the bottom with milk jugs of water. Move them to the top after power fails. Use in the fridge also - as it melts you get cool food and fresh water.
Otherwise, solar and gas powered generators are your options.
Flywheel UPS systems are available off the shelf (so to speak, probably a bit heavy to go an an actual shelf!) e.g.
formatting link
formatting link
If you don't let the speed of the flywheel change, you can;t get any energy out of it. Normally flywheel systems will use the generator off the flywheel to power an inverter that actually provides output.
I recall motor generator sets with a flywheel and gas/diesel engine where the flywheel kept the generator running and started the engine on power failure. But AFAIK these are quite common.
If all you want is to run a fridge, a 100W generator attached to an exercise bike might work. Some of the newer energy-star fridges run on less than 100W.
Now the challenge is to find enough people to pedal at a rate of 100W. It can be done, but not for very long. (At least, if the readouts on the exercise bikes at 24 Hour Fitness are any guide.) Maybe pedal into a bank of deep-cycle batteries, with inverter... now we're talking big capital cost $$$...
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.