Controlling 3 phase BLDC Motors without Hall Effect Sensors

One of the necessary evils of motor control has been Hall Effect Sensors to detect rotational position and speed. They work, but they tend to be the least reliable part of the motor - a blessing and a curse. They overheat and die. Connectors and wires to them break. They add cost. Is there some way to do without them? I suspect there several alternatives, such as optical sensing, but Hall Effect sensors seem to work OK, despite many problems, and they are widely accepted. Is there a better way?

There may be. Texas Instruments describes a new scheme they call "InstaSPIN". In a nutshell, this technique uses back EMF from the phase windings. It turns out there is enough information in the back EMF with which to do some clever computing to derive angular position and velocity of the rotor - and hence derive phase timing for the motor power. It actually learns how to control any 3 phase BLDC motor in a few seconds of operation, using their adaptive software. Warning, this is pretty deep technically, but TI is absolutely credible and this should be taken seriously by those who design motor controllers. Here's the technical video describing the technique:

https://www.youtube.com/watch?v=szgVUfyX8JM

This may be old news for those in the know, but it seems new and possibly revolutionary to me. :lol:

some info / discussion
https://endless-sphere.com/forums/search.php?keywords=instaspin&terms=all&author=&sc=1&sf=all&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search

Also, you may wish to look up "sensorless" as there are many controllers that work that way, too.

Amberwolf, what about RC ESC? It seems to me many of the sensorless controllers operates in Zero Crossing. Time delta assumes cosntant velocity - but is there ever realy constant velocity? Acceleration, braking, oh yeah and standstill. Not much back emf there. Hence the rolling start by pedal.

What other options are there that uses insta-spin? I remember Zomibess did some tests, but did he ver get it working? Is there any products ready to buy over the counter that uses insta-spin - and if so does it work so well as TI claims?

OP mentioned optical sensors as an option to hall sensors. I have seen those for RC motors, and I think there was one for Astro inrunners as well. Are those optical sensors more robust then hall sensors? Or just another way of reaching the same stator info? And do they work well for all kinds of motors, like DD hubs as well? I don't know how big a problem hall sensors really are, it seems people that are monitoring their motor temps are less likely to have problems with halls, is that observation correct?

If I am mixing up things here, it is because this subject is hard to grasp for a non EE guy. But it seems well worth digging into to get a better understadning of motor controllers.

Today i open my magic pie 2 and move out the hall sensors en intern controller.
Now Only use the 3 phase wiring to a non hall extern controller.....runs crazy whit a peak of 45 A :lol: alsmost the dubbel of watts compare to the gm intern controller.