RC Car BLDC motor

Thread Starter

zejulios

Joined Sep 11, 2020
3
Hello,

I'm trying to build my own ESC to control my RC car BLDC motor.
I have a PROPDRIVE v2 270KV and Allegro A4963 develop board, I've tried several configurations and settings and none work.
I've managed to make the motor to run smooth, but the start is always dificult, and also speed controlling is not good.
Anyone can give me a help/hint how to tune the controller with this motor?

Thanks!
 

LowQCab

Joined Nov 6, 2012
255
I quite often like to build my own specialized stuff sometimes too,
but in this case you would be far better off to just purchase an appropriate Controller.
This is the one I would recommend ..... https://shop.powerdrives.net/?product=120f3x
It's Bullet Proof, and the software can be tweaked in every way you could imagine.
It's ~$100.oo, which you are going to spend before you're done with your own version.
You can even re-Flash to different software like "BL-Heli" for more tuning options.
 

Thread Starter

zejulios

Joined Sep 11, 2020
3
Hello,
Thanks for the replay.
I want to build this also for other stuff that i might use the same motor.
I can buy a controller but usually this ready made ones in one year change or cannot get the same, cause it was discontinued...
So building my own I can reuse and adapt to my needs...
Maybe an industrial one can do the job, but Im afraid that Ill have the same tweek issues...
 

LowQCab

Joined Nov 6, 2012
255
BLDC 3-Phase Motors, and their drive requirements, probably won't change for another 10 years,
but the means of communication to those "DC to 3-Phase AC" controllers is constantly evolving.
The ESC (Electronic Speed Controller) that I linked to above will automatically recognize
over 6 different Serial Communication Protocols, and new ones keep coming out about every 6 months.
The ancient, ~40 year old, PPM (Pulse Position Modulation)
is still automatically recognized, and fully supported, if that's you thing, but modern RC Transmitters are
now using far more sophisticated Digital Communication Protocols, for very good reasons.

– Plug and Play Firmware
– Up to 12S capable, (~50V Battery)
– Up to 120 A Continuous current (up to 200 A Continuous is available)
– 200 A Burst current ( 60 seconds )
– True 10bit Throttle Resolution
– Virtually no setup time, with simple motor reversing solder tabs
– Auto-detect ProShot or Dshot at any frequency range
– ProShot1000 capable (1Mbs/s)
– Dshot300 to Dshot1200 capable (0.3-1.2Mbs/s)
– Auto PWM, PPM frequency recognition

– Up to 750,000 eRPM
( number of "3-Pole Sets" in your Motor, multiplied by RPM = eRPM ),
( RPM Ramp-Up, and RPM Ramp-Down, Rate Limiters, so you don't break things )

– Auto Timing Advance
– HBM (Hectic Boost Mode) ensures motor will deliver Maximum Torque, outperforming any other ESC
– Telemetry Output = Voltage, Current, RPM, Over-Temp Current Limiting Mode
– Intelligent current sensing
– LED Status Indication on Board
– Digital commands over Proshot or Dshot
– 8-Layer/ 3oz. PCB to ensure minimal trace resistance

Now, the things that you are having difficulties with ....
Start-up, Locked-Rotor, Motor Braking, Breaking Transmission Gears, Over-Heating, short Battery life, etc.,
are all taken care of automatically by the on-board Processor and Firmware.
The non-proprietary, infinitely adjustable, (and completely FREE),
"BL-Heli" Firmware is well known, and respected in the RC world,
and you can tweak everything you can imagine, and quite a few things that you never thought of.
It has Per-Pulse Current Feedback, automatic Phase Advance, and all kinds of features to protect the
Motor, the Battery, and itself, from over-heating, and all sorts of other unusual circumstances.
( I haven't used the proprietary Firmware that this ESC comes with, but it's probably based on "BL-Heli" )
In addition to this, there are probably various ESC Firmwares that are specifically designed for the
special needs of "Ground-Based" RC Vehicles, (as opposed to "Air-Based" RC Vehicles).
( I haven't looked into this because it's a totally different world,
separate from the Airplane/Helicopter/Quad-Copter world ).

Stop trying to re-invent the wheel,
there are hundreds of really sharp people trying to figure out
a better way to do what you are trying to accomplish on your own,
and they've done a beautiful and astounding job of it.
You're not trying to build a simple PWM Fan Speed Controller.
 

Irving

Joined Jan 30, 2016
1,070
Was the PROPDRIVE 270K the original motor for the car or is this all scratch-built? What are your gearbox/axle ratios?

Your biggest problem I suspect is because your motor is sensorless. Its designed for driving propellers where there is relatively little load on the motor to start (just the inertial load of the rotor and prop). Starting a BLDC motor, ensuring it runs in the right direction and keeping it smooth, requires accurate assessment of rotor position & speed. With a sensorless motor that is done by monitoring back-EMF once the motor is turning but start up needs more of a brute force approach - crudely you pulse one or more coils and see what back-EMF you get. However starting a BLDC motor under load, as in a car where there is no movement until substantial current is flowing in the windings, requires a better way of assessing rotor position. This is where, for any substantial vehicle, you need a sensored rotor and a matching controller.
 
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