Quote:
Originally Posted by efoote868
Well, if you're still in the planning stage, you need to first figure out what you want as the end product, and then you can begin to fill in the details of how to get the end product.
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FRC is an "Engineering Competition". I know your quadcopter is not for FRC but the same though process apply.
Quote:
Originally Posted by tilky
thanks for the pointer about the diode. finally, any suggestions about specific mosfets to buy (don't forget, will be operating at 5v)? and do i need to use resistors at any point, whether from the PWM signal etc.
oh, and is a "snubber diode" a specific type of diode or will any type do?
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The answers to these questions are not rocket science but to properly address them (and the interactions between these choices) would require more than a few posts on a forum like this. If you were in the Houston area, I could help you out. Otherwise, there may be a hacker/maker space near you with someone who has hands-on experience doing this. If you are feeling adventurous, you might consider reading application notes from MOSFET manufacturers such as Fairchild, Infineon, Vishay and others. If you really want to get into it, there are books such as the one by Mohan that are classics in the power electronics field (
http://www.barnesandnoble.com/w/powe...an/1101194755). Unfortunately, quite a bit of the advice you have been given in this thread will likely cause the release of a lot of "magic smoke" and lead you to waste time and money.
Quote:
Originally Posted by nuttle
Bottom line is there's a ton of stuff already done for this particular application and you probably want to at least start with what is readily available and in widespread use. The underlying technology is similar, but you most likely do not want to try to build your own controller -- lots of optimization has already been done, just as for motors for this application.
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Quote:
Originally Posted by efoote868
If I were to approach this problem, I might start by looking at what's available to the average consumer / near hobbyist level.
Controlling a brushless DC motor is not trivial, which is to say that as a hobbyist you wouldn't build one from scratch as you might an H-bridge or other brushed DC motor controller.
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Even though I design large motor controllers for industrial applications in my day job, I would still buy a ready made one for a project like yours since it would be very difficult for me to beat the price. You have more than enough challenges to overcome in other areas of your project.
Quote:
Originally Posted by Andrew Schreiber
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I think these are the ones that several of my co-workers use for their electric airplanes and helicopter.