Back emf detection on Prop 1 for ESC ?
T Chap
Posts: 4,260
Has this ever been done ? I am looking to remove a micro that has been programmed for sensorless bldc control using back emf for commutation and drop in my own. I was thinking to keep their 3 high and 3 low n channel mosfets that use a bootstrap driver ic. Their micro blows very easy when a mosfet burns and it has no current limiting. The main question is now can I get motor position into prop 1 without adding sensors, only using back emf.
Comments
No. You'd need Field Oriented Control.
We need the Prop in their arsenal
I did sensorless with the P2 following info from here https://simple-circuit.com/arduino-sensorless-bldc-motor-controller-esc/ with the Universal Motor Driver P2 Add-on Board 64010 rev A. Unreleased because the motor start process is sketchy.
The bottom line is it's hard to limit current when you can't measure phase current. The 64010 board measures input current.
I previously did some work trying to measure BLDC speed by measuring frequency. The problem is the phase voltages have PWM so it needs significant care to detect the commutation frequency. I abandoned that project. With the P2 I used an ADC sampling window exactly equal to the PWM period. And I used a PWM frequency that's significantly higher than the BLDC commutation frequency.
Hello, thanks for the info. I have abandoned trying to look at back emf. Too much work. Changing to halls for this which is zero thought.
Here is a variation of FOC where three Sine signals that are shifted relative to each coil create a smooth, rotating magnetic field within the stator windings.
Video Example #1:
Video Example #2: What the below video doesn't mention is that the motor has about 100 pounds of spring wound inside of it ... this was a project for a portable battery powered sewer pipe reamer
