BESC - beefed up VESC motor controller for high power ebikes

TilmanBaumann said:

The benefit of winding it like that is lower phase current per driver only?
Naively I would think that a six pole motor can be hooked up to a three phase driver by hooking up the phases in parallel. Is that so?
Sorry for those questions, I just wondered if I understood that right?

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Lower total phase current per controller.
Think of the power curve and smoothness of a 6 cylinder engine vs a 3 cylinder. you get similar effects from 6 phases vs 3 phases.
Yes you can, just be sure you are connecting the correct phases to each other.

For a small motor...like say an 80mm outrunner, there's not much point in it other than to mess with 6 phases, but for larger motors where controller costs start climbing in cost rapidly, there is. Ever look at what a 40kw controller costs? They are NOT cheap...something like $1200. Now look at the cost of 2 20kw controllers. You can probably buy 2 20kw controllers for a little more than half the cost of a single 40kw controller. Go higher...to like 80kw...and do that math again. Those big controllers get expensive really fast!

Yes I know, I bought one recently. [emoji16]
HyPer-Drive X144, nice part.

VESC wasn't quite there yet for me.

However, the price scales more with current than with voltage. I think a lot of he high cost people see, are somewhat self inflicted and avoidable with higher voltage systems.
Either criminal way, that stuff gets expensive fast. [emoji23]

TilmanBaumann said:

Yes I know, I bought one recently. [emoji16]
HyPer-Drive X144, nice part.

VESC wasn't quite there yet for me.

However, the price scales more with current than with voltage. I think a lot of he high cost people see, are somewhat self inflicted and avoidable with higher voltage systems.
Either criminal way, that stuff gets expensive fast. [emoji23]

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I went and googled for that controller...the cheap one started at $4300!!! Holy FAQ! It better be a nice part for that price.

Current vs voltage: A single 300 volt mosfet costs a few dollars and can handle 20 or 30 amps at 300 volts. While to get 300 amps you need 10 of those mosfets in parallel. And then in a BLDC controller, multiply that by 3. So of course the price scales with current handling.

Voltage only gets you so far. If the controller can't keep up with the higher commutation speeds created by higher voltage you are unable to maintain sync with the motor and the system stops working. eRPM is a big show stopper. One of the nice things about the VESC projects is they can all do around 100K eRPM...which covers a ton of voltages on most any motor...assuming you can get a higher voltage VESC. I have 150v controllers, but that doesn't mean anything when the motor runs at 70,000 eRPM at 130 volts and the controller can only do 50,000 eRPM. I need the amperage, voltage and the eRPM and NOT break the bank.

What's more, outrunners for the cost, size and weight outperform just about every inrunner. With one exception...lots of magnets which means lots of pole pairs and therefore more eRPM from the motor. For the cost of an inrunner, I can buy an outrunner that is smaller, lighter and 2-3X more powerful. This is highly compelling and means that I'll probably choose an outrunner over an inrunner 99% of the time and then need more eRPM in the controller to run the motor.

Thank you. Very good explanation of the trade-offs. Especially at the motor side.
And don't worry I didn't pay so much, more like ~2k. https://evshop.eu/en/controllers/63-controller-hyper-drive-sme-acx144.html

Any new development on this controller?

@galp

Still thinking about that open source? I'd like to spin this design for my personal motorcycle conversion project.

Goals for now are

Get BESC to do 300+ A phase current and fit it in "industry standard" extruded aluminum enclosure. I'll also try to make it cheaper. This time I'll go with separate power stage and control stage.

I'll publish latest schematics and layout and you can work from there. I don't think you would gain much if you got actual PCB files. You'll have to delete most routing if you want to move anything anyway.

Schematics would be great! No worries about the PCB files since my goals were to increase max current and lower cost of BOM/build as well.

Were you thinking about running those current sensors in parallel? Allegro has documentation on doing that to increase the total amount of current that can be measured.

Let us know when you have those schematics published somewhere. I would much appreciate it

I was thinking about LEM HTFS 400. https://www.lem.com/sites/default/files/products_datasheets/htfs_400-p_sp7.pdf
It is ~17€ on Farnell. Quite a lot but not necessarily unaffordable especially if we this is going to be 18 FET design with 400 A peak current.

I'd start by making capacitor bank cheaper by removing aluminum caps and finding more affordable film caps. You can't save anything on FETs, they are the best / cheapest for their performance. You could save some by replacing gate drivers with non-isolated ones but I wouldn't recommend it (400A ). Eliminating screw mount terminals and instead soldering wires directly on PCB would also save some BOM cost.

I'm sure I'll find ways to cut costs without sacrificing performance. I intend to keep the isolated drivers but I may switch to through hole FETs for better thermal management. Really appreciate your work here. You and @marcos have been paving the way for higher powered VESC based designs.

@galp are you running the standard firmware for the VESC 6 or did you have to make some modifications?

I had to modify parameters for hardware, that's all.

Wonderful! Looking forward to the schematics. Even just listing the part numbers of the ICs specific your design would be valuable.

Edit: Never mind. I see you have done this on your thread in the VESC forums.

This should be the latest: https://github.com/galpavlin/BESC/blob/master/besc%20proj.pdf

Awesome! I will enjoy reading through this. Good luck on your next version. I may start my own similar design soon. It seems like all distributors are out of stock of the MOSFETs you are using though. I won't be able to make a prototype for a while unless I switch to something else.

shaman said:

I'm sure I'll find ways to cut costs without sacrificing performance. I intend to keep the isolated drivers but I may switch to through hole FETs for better thermal management. Really appreciate your work here. You and @marcos have been paving the way for higher powered VESC based designs.

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Yes please! If something is likely to die in a controller, it's the mosfets. Making them easily replaceable is a good thing. SMD components are far harder to replace than are through hole components. There's lots of good options in TO-220.

ElectricGod said:

Making them easily replaceable is a good thing. SMD components are far harder to replace

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Using through hole FETs have been typical in my designs so far. I'm finding it hard to find through hole FETs with as good of Rds(on) as the SMD FETs used in this design though. The best through hole 150V FET I can find are these https://www.mouser.com/ProductDetail/Infineon-IR/IRFP4568PBF?qs=sGAEpiMZZMshyDBzk1%2FWi5%252BqVgN3%252BWS8LHPsOJRni0k%3D

Rds(on) of 4.8mOhms. Id(silicone limited) of 171A. Total gate charge of 151 nC.
There's a TO-247 FET out there with slightly lower Rds(on) but it only has an Id(silicone limited) of 100A.

TilmanBaumann said:

The benefit of winding it like that is lower phase current per driver only?

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-Much cheaper controller cost despite having to run 2. I regularly run 16kw peak input using a pair of controllers that cost me a total of $158 plus shipping.
-One failure and you can still ride home on just one controller running half of the motor.
-More turns of copper on each tooth for a given Kv results in higher motor inductance than the same Kv wound for 3 phase, which makes the motor easier to drive and controllers more reliable.

shaman said:

ElectricGod said:

Making them easily replaceable is a good thing. SMD components are far harder to replace

Click to expand...

Using through hole FETs have been typical in my designs so far. I'm finding it hard to find through hole FETs with as good of Rds(on) as the SMD FETs used in this design though. The best through hole 150V FET I can find are these https://www.mouser.com/ProductDetail/Infineon-IR/IRFP4568PBF?qs=sGAEpiMZZMshyDBzk1%2FWi5%252BqVgN3%252BWS8LHPsOJRni0k%3D

Rds(on) of 4.8mOhms. Id(silicone limited) of 171A. Total gate charge of 151 nC.
There's a TO-247 FET out there with slightly lower Rds(on) but it only has an Id(silicone limited) of 100A.

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The best TO-220 mosfet at 150v is the AOT2500
In TO-247...well I assumed you were going with TO-220...but in TO-247 that's possibly the IXFK300N20X3 which is a 200v, 300A, 4 mOhm mosfet.

As you probably know, higher voltage almost always means higher Rds. The irony is, go back 5-8 years and Rds under 5 mOhms was epically good at 48v. Now we expect 2.5 to 3.5 mOhms at 100v. Mosfets have come a long way!

John in CR said:

TilmanBaumann said:

The benefit of winding it like that is lower phase current per driver only?

Click to expand...

-Much cheaper controller cost despite having to run 2. I regularly run 16kw peak input using a pair of controllers that cost me a total of $158 plus shipping.
-One failure and you can still ride home on just one controller running half of the motor.
-More turns of copper on each tooth for a given Kv results in higher motor inductance than the same Kv wound for 3 phase, which makes the motor easier to drive and controllers more reliable.

Click to expand...

Hi buddy!

FYI...my next build WILL be using one of the those fantastic 6 phase hubbies. I recently acquired a 100 pound scooter in near perfect condition for $90. So far I have been wondering what I'd do with those 2 hub monsters I have. Now I know where one will go. It's a perfect match for this machine!

Is that 16kw per controller or total for both controllers? I thought the hub monsters could do 40kw MAX total between BOTH controllers.

You and I are on the same trek...looking for that epic 150v controller that can do FOC and run these motors properly at 32S.

I've never found a $79 controller that will handle 16kw peak. I've also never run a HubMonster at 40kw. 30kw is the max I've used and never more the 17kw peak input without cooling mods. If you run much more than 100A per controller battery side, then you need to watch the heat. With my ventilated cooling approach I run at 150A/controller without any temperature worries, but I do have mountains to contend with and if I want to run hard to show up motos I don't want to have to worry about heat. Getting to max power is all about getting to a high enough voltage, because there's no getting around current limits, but rpm limits are still unexplored by anyone.

Get the motor out of the wheel, so you can gear it down, along with a pair of truly high voltage controllers, and then 40-50kw is perfectly reasonable with a ventilated motor that has centrifugal blades on the exhaust side. It would take over 200V for iron core losses to get to 1000W. While I wouldn't want to cruise continuously at that rpm and heat generation with my simple cooling, out of the wheel with some ducting and a filter on the intake, it's reasonable, especially since Miles' spreadsheet predicts 96% efficiency while making 127Nm of torque at 200V at 244A. HubMonster will actually do a bit better than his spreadsheet predicts, as I erred on the conservative side with my measurements, which others have proven with their own slightly better measurements. That was with cheapie controllers, and I'm seeing improved range with my PV controllers pushing one of my HubMonsters, so sine wave means true limits are higher do to improved efficiency.

I have finalized plans for future work. It goes something like this:

• 24 TO-220 FETS

• Three low side shunts (phase current monitoring (hall) is expensive @400A)

• Two configurations of HW:
  • 100V/350A peak phase (20S) with IRF135B203 mosfets (1.8€ per piece)
  • 150V/250A peak phase(30S)

• Cost effective (BOM under 100€ for 20S version)

• Standard extruded aluminum housing

• I'll design everything in KiCad because what's the point of opensource project if you need 8k licence just to open files.

galp said:

I'll design everything in KiCad because what's the point of opensource project if you need 8k licence just to open files

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galp said:

24 TO-220 FETS

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Perfect!

galp said:

Three low side shunts (phase current monitoring (hall) is expensive @400A)

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What shunts do you have in mind for this?

I declare this project open source.

Take a look at schematic draft here: https://github.com/galpavlin/BESC-G2/blob/master/besc%20g2.pdf
Other design files are also available in the repository.

shaman said:

What shunts do you have in mind for this?

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I'll be using two 200u shunts in parallel and INA240 amplifier. It has low offset voltage, low drift and survives up to -8V common mode voltage. https://github.com/galpavlin/BESC-G2/blob/master/datasheet/shunt.pdf