looking for info on controlling brushless motors

[deltatechx]

I've been doing some research online and have found some vague information on brushless motors. All of the ESCs that I've seen have a three wire control input but none have any information about what kind of signal input it takes to run the motor. I saw something about 1 ms, 1.5 ms, and 2 ms signals on wikipedia but no real specifics.

I'm not building an r/c vehicle. I'm wanting to use a brushless motor as a starting motor for a turbine engine I'm building and basically want to be able to hold a button down to spin up the turbine for ignition. Eventually the entire startup of the turbine will be controlled by a Basic Stamp microcontroller.

While stumbling around with google, I saw brushless motors being used on electric bikes with regenerative breaking capability. Would I be able to use this with a 1/8th scale Feigao 540XL - 7XL motor, basically having it act as the starter motor and then as an alternator while the engine is running. Also, what would be the maximum rpm the motor could physically handle and what would be the optimal rpm for using the motor as an alternator? The turbine engines I've seen on the internet run up towards 100,000 rpm and higher, I'm guessing the motor wouldn't be able to handle that so I'd need to use reduction gears. Any help would be greatly appreciated. Schematics for a custom ESC with regenerative breaking would be awesome.

If you have any questions, suggestions, or info please feel free to post.

Thanx in advance :wave:

[deltatechx]

ok, for right now what I need to know is how to trigger the ESC to drive the brushless motor. I know the brushless motor connects directly to the ESC, what I don't know is if connecting the main power to the ESC starts the motor or if a signal is required to the three pin connector (I also know the three pin connector connects to a programming card to program the ESC). To start with I'm just going to use a centrifugal clutch so the motor spins the turbine and then disengages whenever the turbine spools up under its own power. I'll worry about using the brushless motor as an alternator later in the project.

I already have the turbo, the lubrication components are in the mail, and a local shop is fabricating the combustion chamber and flame tube. I'd rather spend the money on the motor and ESC rather than purchasing a leaf blower to start the turbine. Any help on this would be greatly appreciated.

Thanx

[aconsola]

ok, for right now what I need to know is how to trigger the ESC to drive the brushless motor.

The thin three pin connector that goes to the ESC is usually connected to a radio receiver, the input signal being generated by the radio control handset/transmitter.

The wire is most commonly black/red/white with black/red being -/+ supplied by the esc to provide power to the receiver unit. The white wire is the signal wire which would control the function of the esc.


instead of a radio control set you could use something like this to provide the input signal to the esc until you can build your own into the overall design of your project:
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXVK79&P=7

hope that helped.

[deltatechx]

Thank you, that'll work perfectly for now.

[kufman]

The signal on the white wire is a 1 to 2ms (or there abouts) wide pulse that repeats every 20ms (50Hz). Not everyone follows the same convention in regards to direction. Some use the increasing pulse width to indicate more throttle and some use the opposite.