RC Motor Issues

[dirttorpedo]

So I finally got around to setting up my Kepler Drive commuter this weekend and I think I killed 2 VESCs. I'm using an FOCBOX and a Turnigy 6354 260kv. I plugged in one phase wire and as soon as I got the second one in the motor started twitching and suddenly stopped. In BLDC Tool I'm getting detection fails on some things and not others. I can see in ADC programming that my throttle is working properly, it's just not powering the motor.

Now the really dumb part. I tested the the phases on the FOCBOX and the middle one tests like there's a bad FET. I ASSumed the controller was the issue since I picked it up on ES. I tested the phases and I plugged in a second FOCBOX. This time the motor made a high pitched whine for a second when the second phase was plugged in. I pulled it out quick but not quick enough. Now it's behaving the same as the first FBOX.

So I'm pretty sure the motor has a short somewhere, even though it's brand new, but I'm not positive. How do I test this? How easy is it to take apart? Is it just the little c-clip on the shaft? And while I'm at it, does anyone know if there anyone around doing VESC repairs?

 

[district9prawn]

Why are the phases being driven while you are hooking up the motor? Throttle settings?

Even if the motor is faulty or a mosfet has failed in short circuit, you wouldn't expect things to blow until you drive the gates by giving some throttle or running motor detection.

To test phases try running constant current through two terminals and measuring the voltage to get the phase to phase resistance.

 

[dirttorpedo]

Why are the phases being driven while you are hooking up the motor? Throttle settings?

Even if the motor is faulty or a mosfet has failed in short circuit, you wouldn't expect things to blow until you drive the gates by giving some throttle or running motor detection.

That's exactly what I can't get my head around. I plugged in my battery and the phases and got twitching on the first controller, the weird noise on the second controller. I didn't have a throttle plugged in when the damage occurred. Didn't get a chance to run motor detect until after. As far as I know both FOCBOXes were brand new with default settings. I was pretty much just plugging in to set it up and make sure the throttle setup worked. I didn't get as far as plugging in the throttle because upon plugging the phases in I knew something was wrong.

The middle phase has no resistance to +/-, same as my trail bike controller when I blew a FET a few weeks ago. I figured what the hell and plugged the throttle into the ADC inputs afterwards and BLDC shows the throttle working through the controller. I have no idea how I would have blown a FET simply plugging in phases other than a short somewhere. I pulled apart my motor and there doesn't seem to be any issue that I can see. I have a cheap ESC and a servo tester coming from HK as my next step.

 

[amberwolf]

A controller should not do anything at all until you command it to, but some FOC controllers do, by continuously sending "random" (not really) "noise" pulses to the phases to get feedback from teh motor coils to determine motor position and rotation speed.

For example, Incememed's SFOC5 controller: When I first started beta testing it, this was a severe problem on my heavy SB Cruiser trike, in that it would actually move the trike back and forth just sitting there, without me on it, a tiny amount. With me on it, vibrations would shake the trike from teh low frequency components of these pulses, as if I had an internal combustion engine idling on there instead of an electric motor, when the trike was just sitting still, not moving. There was also a loud "hiss" from the high-frequency components of the pulses, that was very annoying, and could be heard over other noises as I rode the trike. (I even got a video of the issue with the noise still audible over a helicopter flying overhead!).

This has been fixed, since then, but if there is something wrong with your motor(s), like a short between phases/etc., then even just these positioning pulses could damage the controller if it doesn't have sufficient protections against that sort of thing.

 

[dirttorpedo]

I had a chance to test my motor this weekend with a $10 ESC and a servo tester from HK. The motor is working just fine. I'm still not sure how the heck I killed those FOCBOXes but at least I can get a commuter going. I have a cheap 6FET controller on the way but I'm seriously considering wiring the servo to take a throttle and just using the ESC as my controller.

Anyway, thanks for your help guys.

 

[dustNbone]

Might be a good idea to disconnect supply power while connecting/disconnecting phase wires?