Powerng a DC Brushless Motor with a Charged Capacitor

Im afraid you cannt drive the brushless motor with only a capacitor.

do you know what the brush mortor ?

I may be able to help if you supply some more details, but you have some serious hurdles to overcome.

First, what is the current draw of your motor? If you plan on running it for more than a few brief moments you will need way more than that capacitor.

Second, BLDC motors require driver circuits to provide the right timing to the coils inside the motor. Do you have the appropriate driver circuit or do you need a full design of that also? If so you should google BLDC drivers and see what you are getting into.

Good Luck

-Doug

The energy stored in a capacitor = 1/2 C V2 With C in mili of micro farads , how many MVs do you want to store in it ? And also mind it as the capacitor discharges, the voltage will drop

If, as you appear, to not have a clue with regards to energy, energy levels, energy conservation etc., you do have a shock coming up that depending upon the size of the motor (if you don't need a magnifying glass to find it, its too big!), it may turn say just once (if you are lucky, it may not turn at all!) and the capacitor is empty.....

If there is a specific reason behind your question, or a specific use, then perhaps you should tell us the whole story first, but if I was going to try and do what you appear to be trying to do, I would start with a tiny motor and a capacitor about the size of your back garden!!!!!! Then you might get the motor moving for an hour or so!!!

The next problem that you have, is how are you going to charge your capacitor? Using electricity that you need to pay for is not going to be very efficient, so you need a reasonable source of power for nothing.......

But as we do not have the foggiest idea of what you are trying to do, all of these comments are probably totally off base....

Best wishes.

we don't pour cool water on your so higher passions, but your fluent English appeared to act as a countryman's conversation. Lets stopped to talk about the sun's color temperature (you might have to read book temporarily)

Here, at the mere mention of DC or glance at a motor word, you might imagine that can be drived by a battery or a capacitor has enough energy. stream down so much fluent, wonderful words to the top thread to show off. its pity. you seem don't know what is DC motor or AC motor.

no matter how "big, fat" DC power you poured into the motor mentioned by the top poster, the motor would not act at all. until it was burned off.

next you might say, what I pointed out is big motor ,large scale type, as large as back garden, not that toy motor.

he he. not offend, Merry Christmas.

I received an early Christmas present this year. It's a radio controlled model helicopter powered by 4 electrically driven motors and rotors. Power to the motors appears to be supplied by supercapacitors that are charged in a docking station by AA batteries. The supercapacitors store enough energy to keep the model aloft for 5-10 minutes at a time without recharging. These capacitors store a massive amount of energy per unit weight.

Hi welderman,

Do they use PWM circuits, I would think that would be the simplest way if brush type motors with PM stator or are they PM armature with switched stator windings.?

Just curious I expect the whole design should be as light as possible.

Garth,
I guessed wrong; it uses Li-Po batteries charged from the docking station, not supercapacitors. The electronics are encased in a foam body and not accessible to view. I have a friend who has a defective one. If he lets me, I may take it apart and examine the electronics.

The most energy this can store without exploding is 0.128-Joules. There are ways to convert the energy stored in the capacitor to drive the motor, but first you should calculate whether this is even interesting.

The length of time will be somewhat less* than 0.128/2/current seconds. So, unless this is an ultra-low-power motor you won't get as much as a second - which so far as I know is only useful for activities that I would not wish to be associated with.

*I say somewhat less because the conversion will not be 100% efficient, and also no electronic circuit will be capable of using all the stored energy

hi again,

actually, i dont have the details of the motor, its a nokia cellphone's vibration motor, brushless DC.

Actually, if I remember correctly those motors aren't BLDC's, they are just straight PM motors. That makes it much easier to manage. A 1000 MFD 16v cap still won't give you much run time on that motor, but you may be able to get a little.

You may be able to get a LM 317 power controller to work for you. Here is the general description of the power controller chip.

http://en.wikipedia.org/wiki/LM317

You will still need to figure out if the current draw of the motor, both startup and running draw, will be too much for the Cap. I am honestly fairly sceptical that that capacitor will give you the power you need to run that motor for more that a brief moment.

Good Luck

Doug

You appear to be using this site to promote your business ? am I correct?