Low speed and startup torque (BBSHD ebike)

General topics and discussions about the VESC and its development.
[phpBB Debug] PHP Warning: in file [ROOT]/vendor/twig/twig/lib/Twig/Extension/Core.php on line 1236: count(): Parameter must be an array or an object that implements Countable
amund7
Posts: 10
Joined: 10 Jul 2017, 08:05
Location: Oslo, Norway
Contact:

Low speed and startup torque (BBSHD ebike)

Postby amund7 » 10 Jul 2017, 08:19

Hi,

I put a VESC 4.12 on my Bafang BBSHD (crank drive), as the original controller died.

It runs pretty good in BLDC mode, with 'stock' settings for the BBSHD, that is 30 battery amps. I am running hall sensored.

Except on steep first-gear climbs, where I couldn't possibly pedal alone. Then duty cycle starts going down, until there is almost no help from the motor. It starts strong but goes down.

It is NOT temperature, I am logging everything, and the temp sometimes reaches 80 degrees (temp limit start), but I have plenty of examples of the same on 60-70 degrees as well.

I found the 'mimimum RPM' setting, and after seeing the source code (for current control) I understand that only BELOW 'min rpm' will it start reducing the duty cycle and therefore the amperage and torque. So I set the min RPM to 1, but still the same thing happens.


What else, except min RPM, amp limits and temperatures could pull the duty cycle down from 95%?

I am working on a USB wired raspberry PI that will give some good detailed graphs, I will post them soon, but what I can already see from jerky logs off VESC Monitor/bluetooth is that the duty cycle goes way down, less than 50%, battery and motor amps are far from the limits, and the temperatures as well. So I can't figure out what's reducing the duty cycle ?

Sorry for the long post.

TL;DR: Vesc reduces duty cycle on slow hills, why? It's not temperature, lower RPM limit or amps.

rew
Posts: 943
Joined: 25 Mar 2016, 12:29
Location: Delft, Netherlands.
[phpBB Debug] PHP Warning: in file [ROOT]/vendor/twig/twig/lib/Twig/Extension/Core.php on line 1236: count(): Parameter must be an array or an object that implements Countable

Re: Low speed and startup torque (BBSHD ebike)

Postby rew » 10 Jul 2017, 08:53


amund7
Posts: 10
Joined: 10 Jul 2017, 08:05
Location: Oslo, Norway
Contact:

Re: Low speed and startup torque (BBSHD ebike)

Postby amund7 » 10 Jul 2017, 09:12


devin
Posts: 255
Joined: 08 May 2017, 01:55
Location: San Francisco, California, US
[phpBB Debug] PHP Warning: in file [ROOT]/vendor/twig/twig/lib/Twig/Extension/Core.php on line 1236: count(): Parameter must be an array or an object that implements Countable

Re: Low speed and startup torque (BBSHD ebike)

Postby devin » 10 Jul 2017, 13:05


rew
Posts: 943
Joined: 25 Mar 2016, 12:29
Location: Delft, Netherlands.
[phpBB Debug] PHP Warning: in file [ROOT]/vendor/twig/twig/lib/Twig/Extension/Core.php on line 1236: count(): Parameter must be an array or an object that implements Countable

Re: Low speed and startup torque (BBSHD ebike)

Postby rew » 10 Jul 2017, 17:17


amund7
Posts: 10
Joined: 10 Jul 2017, 08:05
Location: Oslo, Norway
Contact:

Re: Low speed and startup torque (BBSHD ebike)

Postby amund7 » 14 Jul 2017, 06:35

Thank you all for very educating posts!

I have the raspberry pi logger/monitor up and running, which writes 50hz CSV files. And I learned was very embarrassing - in all my back and forth with settings I had set the min RPM to 150 ??? and max motor amps to 40. I don't know when or why I did those, but those combined are probably causing my issues, will test again with new settings today.

Motor amps, how can I guesstimate the sane max for my motor? I am thinking that as long as I am still missing the low-end torque the original controller had, I am well below the original motor amps?

devin
Posts: 255
Joined: 08 May 2017, 01:55
Location: San Francisco, California, US
[phpBB Debug] PHP Warning: in file [ROOT]/vendor/twig/twig/lib/Twig/Extension/Core.php on line 1236: count(): Parameter must be an array or an object that implements Countable

Re: Low speed and startup torque (BBSHD ebike)

Postby devin » 14 Jul 2017, 13:34



[phpBB Debug] PHP Warning: in file [ROOT]/vendor/twig/twig/lib/Twig/Extension/Core.php on line 1236: count(): Parameter must be an array or an object that implements Countable
[phpBB Debug] PHP Warning: in file [ROOT]/vendor/twig/twig/lib/Twig/Extension/Core.php on line 1236: count(): Parameter must be an array or an object that implements Countable

Return to “General”

Who is online

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