Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. It only takes a minute to sign up.
Sign up to join this community
I'm trying to figure out how to control the speed of a 400-watt, 3000RPM, 48V BLDC with Hall sensors with a Raspberry Pi 3. I've been able to find information where people will us an ESC like this between their rPi and the motor but these seem to always be connected to small motors like airplane motors and not the one like what I have. But then I've also seen controllers like this and then also little boards like this.
I would appreciate any direction someone might be able to provide. Thanks!
I recommend not to control the motor directly through the Raspberries' own PWM ports because that requires tight real-time and 400W isn't forgiving if something fails with that.
It might be doable, 50 rps is just at the border of what you could do with a realtime process and one CPU core dedicated to that. Don't even think to use a Raspberry Zero, B+ or similar single-core board for that, you would need multicore.
OR you put a dedicated motor controller IC on a custom hat (I guess there are some you could simply buy) and control that one with any Raspberry or other small Linux box. That is the way I recommend.
I would tend to use an ESC of some form independent of the pi rather than trying to do the speed control itself on the pi. The board you linked to will convert a PWM signal and a digital signal to speed and direction control, and give feedback as pulse per revolution, which would allow higher level control by the pi, or you could use a serial ESC and have that loop on the ESC too. (You could do the same with the hobby ESC and connect a hall sensor to the pi for second loop control, but the hobby ESC won't be as precise and a sensored ESC can be).
What's best depends on other requirements - you won't get vector control or precise low speed operation from a cheap pre-built ESC. You can get higher voltage ESCs, but I've built mine own rather than buying them, as they tend to get more expensive, and at those sort of prices you'd be better off with an odrive. If using something like the ESC board you linked to, you'll probably need to level shift both ways to convert your PWM to the 0-5V range, or you could use a digital potentiometer or DAC instead. Instead, I've tended to create such signals from arduino nano clone and connected that via USB through an isolator, and run any PID on the arduino instead, but that's because I assume I'm going to blow thing up.
I've done this for 480W motors with a simple Arduino + three half bridge based ESC, and serial control of that from pi.
I made my own sensor-ed BLDC controller from arduino ( 16Mgh single core ) and 3 power bridges. I've tested to over 7000 RPM and I'm sure it can manage a lot more then that. I'm sure the 1Ghz single core of a RPi0 is more then capable of handling your brushless motor even with the burden of may other operating system tasks.
