VESC and HobbyStar 56112

Report your hardware problems here. Include as many details as possible with pictures to get the best possible help and feedback.
skipper762
Posts: 9
Joined: 13 May 2017, 06:08

VESC and HobbyStar 56112

Postby skipper762 » 13 May 2017, 06:30

Hi Guys,

I am trying to get the VESC to run with a HobbyStar 56112 -3Y motor
http://www.rcjuice.com/hobbystar-56112-4-pole-brushless-sensorless-motor-1-5-scale.html

These are 540KV motors (Don't worry these aren't going on an electric skateboard).

When I connect them to the VESC the BLDC detector cannot find the settings for the motor, I have tried a huge number of different settings (about 2 hours worth). During the testing the motor spins up and down and idles smoothly (I guess like it should).

With the default settings I can get the motor to run fast (2000 ish RPM) , but with no torque (I can stop the bear motor shaft with my fingers).

I have tried with multiple VESCs and motors

What am I doing wrong? Does anyone have any pointers on how I can get the motors to run with better? I really want to use the VESCs as i like the high custom-ability of them.


Cheers,
Nick :D

rew
Posts: 904
Joined: 25 Mar 2016, 12:29
Location: Delft, Netherlands.

Re: VESC and HobbyStar 56112

Postby rew » 13 May 2017, 09:44

Those "product photos" with a sterile background are great for viewing the product. But you lose your sense of scale. that's a MUCH bigger motor than I thought from the picture.

If you convert the 540KV (580? ) to SI units, you get 540/60 = 9 rotations per second. A rotation is 2PI radians, so that's 56 rad/sec per volt.

This in turn means that the motor will produce 1/56 = 17.7mNm torque per A.

So if you set "1A" motor current, that 17mNm will spin up the motor just fine to the max RPM. (30k RPM!), but you'll easily stop it with your fingers as 17mNm is not that much. (ok. they specify 1.9 idle amps, so 2A will spin it up all the way, 1A won't. So sue me).

So you need to better specify what you are doing to get it to spin, as you say at 2000 RPM.

What duty cycle are you seeing for 2000RPM? What happens if you set that dutycycle using the BLDC_tool controls and THEN try to stop the motor?

Did you run the "detect parameters" procedure in the BLDC configuration tab? Most motors spin with the default settings, but work slightly better when running with their own detected parameters.

skipper762
Posts: 9
Joined: 13 May 2017, 06:08

Re: VESC and HobbyStar 56112

Postby skipper762 » 15 May 2017, 02:17

Thanks for your reply,

I can't get the motor to run faster than 5000 rpm (measured with eternal RPM meter) at this speed the duty cycle is ~40%.

I setting the duty cycle to 40% using BLDC tools results in 2000rpm (measured) rotation and an actual duty cycle of ~18%. At this point i am thoroughly confused.

One point to note is that the ERPM reading from BLDC tools matches the measured reading, i thought it shouldn't as it should be multiplied by the number of motor poles. I.E RMP(measured) * poles = ERPM

I have tried running the detect params but to no avails just about every setting i have tried as resulted in "bad result".

skipper762
Posts: 9
Joined: 13 May 2017, 06:08

Re: VESC and HobbyStar 56112

Postby skipper762 » 27 May 2017, 04:04

All right I got it, it's taken me an embarrassing amount of time.

I had forgotten to set the voltage cutoff start/end variables so none of the detection or running was working properly.

Thank you for your help @rew

rew
Posts: 904
Joined: 25 Mar 2016, 12:29
Location: Delft, Netherlands.

Re: VESC and HobbyStar 56112

Postby rew » 27 May 2017, 07:30

You're welcome, but... could you expand a bit more on what was wrong? I want to learn from your mistakes so that I don't have to make them myself. :-)

skipper762
Posts: 9
Joined: 13 May 2017, 06:08

Re: VESC and HobbyStar 56112

Postby skipper762 » 27 May 2017, 07:40

So I had set the battery upper and lower limits but not the battery cut off start and finish.

The motor would spin up but never reach max speed. The autodetect would also not work.

Does that explain it?


Return to “Hardware Problems”

Who is online

Users browsing this forum: Bing [Bot] and 2 guests