BLDC VS FOC, a discussion

I couldn’t find any info on the subject in the search so I figured I’d start it up on this forum.

What are the benefits and disadvantages of BLDC and FOC?

Is it personal preference, performance, or something else that makes you prefer one over the other?

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It has been discussed in the builders forum back then, don’t think anyone started/copy it over tho…

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Only advantage I can see to BLDC is a slightly higher top speed than FOC

FOC is quite, more efficient and way way smoother than bldc.

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BLDC is like having a horn. Your like loud enough to scare people on the sidewalk to move away.

FOC is great too but I get annoyed because people hog the sidewalks and don’t hear you. :sob:

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Lowkey I deal with this at school but at the same time I don’t mind if I get less stares by being quiet lmao

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I like what you’re doing here @RedBaron, a lot of these types of topics are not covered on this forum.

From what I understand, it seems that FOC requires higher quality hardware to run reliably. Some older esc’s could technically run in FOC mode, but were apparently more reliable in BLDC. Perhaps someone with more knowledge can clarify or correct. :v:

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I might be crazy, but sensored foc has less torque than bldc for me. I swear there is a noticeable difference despite identical power consumption and riding style

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You’ve gotten identical power consumption? Its comments like these that have always made me second guess using bldc. I don’t have many hills in my area so I don’t mind pushing to avoid cogging. So if I get a few more mph top end without really losing on my capacity then bldc is a win for me. I also like a loud board because people tend to be more aware of my presence.

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Power consumption when offroading the same terrain is extremely similiar, to the point i would say its the same.

The difference is, with bldc i can do wheelies easier and on foc i cant

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FOC and chains than. Works a charm for me :sweat_smile:

Wheelies are just a matter of settings.
I run FOC with 0.1sec start up ramping and 15% throttle curve. If I push the trigger the front wheels take off easy if you don’t actively push them down.

I personally like sensored FOC for mtb stuff as it just perform better if you start on a hill or roll a bit backwards or similar situations where the wheels are a bit locked due to the terrain.

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I dont change any other settings than the basic vesc setup when i switch between foc and bldc. I assume its the same throttle curves and ramp times

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Is the startup ramping similar to startup boost on BLDC?

What does your curve end up looking like? I assume you are using a 15% exp curve

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Yes it is. The thing I wanted to say is, that the „weak“ parts of FOC can be tuned with the right settings so that the overall performance is better. I can’t do that the other way round with BLDC.

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It’s positive ramping and negative ramping in your ppm settings. It should be same for FOC and bldc.

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I would like to add a video from @rich a while back where he point out some situations where it’s worth comparing FOC and BLDC

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I like BLDC because it makes more noise. Not only can I hear what’s happening down there, but pedestrians can hear me as well.

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@Andy87 Kinda wanna try out FOC for once maybe. I wonder how different my AT Board will ride ?? All I have rode is BLDC but was always worried about damaging the ESC. But that video is very much convincing me too try it out :face_with_monocle::face_with_monocle:
& I also like the sound in BLDC, I like the winding sound too :grin::grin:

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image
FOC

BLDC

close topic

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For competition we all use BLDC. It brings more punchy throttle response and even allow to pass some corners where FOC struggles.
It’s just a pity that the development is now only focus on FOC.
I made a request for that (here : https://vesc-project.com/node/963 ), but I think I’m dreaming.

So now :

  • AT boards = BLDC
  • Street & hybrid boards = FOC

And if you’re still not convi ced, try doing Wheeling in FOC and BLDC. You’ll be amazed by the ease that provide BLDC.

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