Brushless motors

Hi. Would I be correct in thinking that it is only possible to drive 2 brushless dc motors using this board as they are similar to stepper motors?


piborg's picture

Probably not, but you may be able to drive one.

In order to drive a BLDC correctly you really need three outputs with the ability to set power levels, such as PWM.
Each output on the ZeroBorg has only one side PWM controlled, not both.
This means there are four controllable power levels, you would want three of these to drive a single BLDC.

You would probably be better off looking for a board which is actually designed with BLDCs in mind.

Thanks, that makes more sense now. I really appreciate your quick response and comprehensive answer as always. I will probably get some brushed motors for this project.

I am wondering it be possible to drive 4 BLDC with this approach though:

1. Connect each of the 4 PWM controlled ZeroBorg outputs to the ESCs' BEC/servo connector. To prevent the ESCs from supplying 5v to ZeroBorg a BEC of "Optio" type could be used I think (I'm only interested in the PWM signal)

2. Connect the remaining ESCs +/- power inputs to the ZeroBorg two pin screw terminal labelled V+ / GND.

Your thoughts would be very appreciated! :)

piborg's picture

That should work with the ESCs driving the BLDC motors directly.

I do not believe it would be necessary to use an opto-isolated ESC, but it would prevent the possibility of a miss-wiring causing damage.

You will want to stick with either +ve or -ve power values to the ZeroBorg on each motor.
This is because the PWM signal will change side depending on the direction used.

That's great, worth considering. Thanks for the heads up!

When you say stick with either +ve or -ve I think you mean when commanding the Zeroborg via its Python library?

If sourcing power via the pin screw terminal labelled V+ / GND, is it still limited to 1.5A as with the other terminals? Or would it be 5A (after which the fuse blows)?

Thanks for the continued support, much appreciated.

piborg's picture

The actual limit will depend on how the battery is connected in that case.

If the battery is also connected to the V+ and GND screw terminals then the current will be limited to what the wires / battery / motor are rated for.
In effect the ESCs are connected in parallel to the battery this way and they are not really loading the motor outputs, just using them as a signal input.

If the battery is connected via the 9V connectors I would suggest staying within 5 amps as a safe limit.
This is because the V+ track on the PCB has to handle all of the power from the battery.

Thanks for highlighting the option of connecting the battery in parallel like that. It's obvious now that you mentioned it. I should have enough knowledge to attempt this build now, thanks again!

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