VESC 6 voltage/design limits?

General topics and discussions about the VESC and its development.
MatthiasU
Posts: 2
Joined: 30 May 2017, 09:09

VESC 6 voltage/design limits?

Postby MatthiasU » 30 May 2017, 09:31

What's the maximum number of cells you can safely use with the VESC? (Specifically Vesc 6)

My current Ebike has 14s; I want to replace the controller because it only has a binary brake/regen input which doesn't work at low speed; plus I want to add features like theft protection (electronic wheel lock, not just shorting the motor).

If 14s is too much for safe regen braking on a stock Vesc, what's the limiting component?

JTAG
Posts: 11
Joined: 05 Apr 2016, 13:08
Location: Leeuwarden

Re: VESC 6 voltage/design limits?

Postby JTAG » 30 May 2017, 10:10

12S is currently the advised max. What prevent us from designing higher voltage VESC's easily is the DRV that is limited to 60V. In the future (in about 3 months? isch) when the VESC framework is a bit more hardware independent we might be able to design a higher voltage.

MatthiasU
Posts: 2
Joined: 30 May 2017, 09:09

Re: VESC 6 voltage/design limits?

Postby MatthiasU » 31 May 2017, 07:43

Thank you. I should be able to support that effort, either financially or by doing some actual work (both coding and hardware).

lizardmech
Posts: 171
Joined: 19 Jan 2016, 10:54
Location: Australia

Re: VESC 6 voltage/design limits?

Postby lizardmech » 31 May 2017, 09:16

I have a custom one running up to 80V. The two biggest issues are always current sense and a suitable voltage converter. Hall based current sense are slow while high end isolated solutions use delta sigma modulators or differential analogue outputs. At the moment I use LM5161 buck converters which work well and support up to 100V. I haven't been able to find a nice compact solution that has a wide input range such as 30v-200v, all the ICs for small chargers and USB adapters usually have 70v UVLO and only support flyback. Anyone know of an IC with a very wide input range that can deliver 1A current and supports buck or flybuck designs?

User avatar
TheFallen
Posts: 67
Joined: 26 Oct 2016, 10:49
Location: UK
Contact:

Re: VESC 6 voltage/design limits?

Postby TheFallen » 05 Jun 2017, 13:09

Problem with wide input ranges is minimum 'off' times. Converting 5W (5V @ 1A) at 30V vs 200V requires 15 times longer 'on' time so it'll be really inefficient at anything other than the design voltage.

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

Re: VESC 6 voltage/design limits?

Postby rew » 06 Jun 2017, 06:12

Why 15 times and not 8 times?

User avatar
TheFallen
Posts: 67
Joined: 26 Oct 2016, 10:49
Location: UK
Contact:

Re: VESC 6 voltage/design limits?

Postby TheFallen » 06 Jun 2017, 06:50

Yeh, sorry, closer to 8 than 15, but either way the massive difference in input voltages kinda kills efficiency.

lizardmech
Posts: 171
Joined: 19 Jan 2016, 10:54
Location: Australia

Re: VESC 6 voltage/design limits?

Postby lizardmech » 06 Jun 2017, 08:03

Efficiency doesn't bother me that much, lower voltages would mainly be for testing, having 80V minimum voltage is just annoying if you trying to configure it or testing various settings. 80V+ DC power supplies aren't common even if you have a 120v battery pack in an ebike you probably don't want to have to remove it every time you want to run the controller on a desk.

Jackl
Posts: 10
Joined: 12 Mar 2017, 22:23

Re: VESC 6 voltage/design limits?

Postby Jackl » 19 Jun 2017, 19:27

Why not hook up a bench powersupply to supply the low voltage rails during tests/programming on the desk?

Requires a spare power supply of course, but there are quite cheap ones on the market...


Return to “General”

Who is online

Users browsing this forum: No registered users and 1 guest