I must be doing it wrong, foc before I fried my fs4.20 was soo much better then bldc on my fs4.12. Much more torque, smooth, and quiet.
@RedBaron I was literally penning this topic when yours popped up. When I first used focboxes I set up with foc because focbox. Previous to that I had been strictly bldc and I just preferred the feel of bldc so switched back. I have run sensors once and they broke after 50 miles so sensorless all the way now. When the sensor pcb failed on the motor it somehow took the vesc with it so never again will I risk that. I get very minimal cogging and only on hill starts but it literally just requires either a small hip flick or more throttle input. I would not change the sound of screaming sk3 motors for the world though and without changing anything on the throttle curve you get this silly mid range power band that is fully addictive.
BLDC for me
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I just cut my sensor wires off, lol. Bldc for me too.
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I’m in the middle of setting up a build now with gears so it will be interesting to see the difference with a more direct torque transfer.
I could only get my pre-fix FLesc 4.20 to run in FOC mode and only halfway decent. Im really looking forward to configuring BLDC on my cheapFOCers if its as punchy as yall are saying. While I’m not too concerned about having to rebuild my FOCers (being that i know how to build them) if the sensors go out. Im not sure I can just ‘be without’ sensors 
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That’s what I was thinking, I love just standing and smoothly starting with no effort at all. Sensors all the way
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Ive never had that, the FLESC 4.20 never ‘started nice’ not without a considerable amount of feathering of the throttle. But it was definitely not ‘cogging’.
Oh weird, maybe that’s just because it can’t run foc as well, I have focbox’s, always had smooth start
It was nice to not have to hump the air to get moving but a flick of the throttle would make it fault out lol. Its alright, i have melted it down into 2 MTU’s and 2 DRV8302’s for some extra FOCers solid 25 bucks worth of IC’s right there!
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Oof haha yeah good move
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anyone has a video/gif of the motor phase wires of FOC vs BLDC?
(animation of oscilloscope is ok)
Bldc is wild you guys. It’s almost too much powa!!! Felt like I was riding lightning.
Summary of the comparison, assuming a motor controller implements both correctly.
Trapezoidal Control
- Higher electrical power output and torque before the motor controller overheats
- Less CPU intensive, meaning more resources for other tasks
- Less emitted EMI
- Smoother current control response
- No tuning required, even for BEMF integration (too bad the vesc isnt smart enough for that)
- Good tracking
- Torque Ripple, and as a result, more noise and lower efficiency; this makes little difference at high speed.
- Poorer dynamic load response
- Stuttering and inefficient startups, partially alleviated with sensors, but basically needs a decent kickstart.
Field-Oriented Control
- Higher efficiency, less noise and torque ripple.
- Smooth startup, even in sensorless.
- Servo control
- Reverts to trapezoidal control at high speeds but with increased heat generation.
- More CPU intensive
- Less electrical power throughput before motor controller overheats.
- Increased EMI
- Algorithm is more sensitive to disturbances at low speed.
But the vesc has its own quirks, FOC has poor tracking and torque generation at low speeds, BLDC requires tuning for whatever reason, but is more rugged to disturbances. Sensorless BLDC at low speed doesnt seem to work at all.
If designing a motor controller from scratch, BLDC has significnatly less rigorous hardware requirements, enabling low cost.
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Ah yes, the small hip flick. So much preferred in my opinion than sensors, which is one more part that can fail.
Once you master the hip flick, sensors are just a creature comfort but are wholly unneeded.
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Do you hold the brake and flick the hip or just flick the hip?
flick? I must have been doing this wrong. Last time I tried to get going on a board without sensors they banned me from the school grounds for “sexual misconduct”… hindsight, I probably shouldn’t have also said “get it you little bastard”.
Real talk though, yall are making me itch for some sweet punchy torque from BLDC… Curious, if I programmed an MTU before removing it from a board, and transplant it on another will it work ?
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Release the brake simultaneously as you flick your weight forward and pull the throttle. Once you get the wheel turning almost any amount, the power takes over.
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Let’s peel this one more layer.
Are we talking dual drives or single? The difference in power/tq in a dual drive bldc and foc might be more negligible then a single drive bldc vs Foc.
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