Our lab previously purchased several BLDC motors with 21 pole pairs and 36 stators. These motors did not come with hall sensors, and previous lab members produced a pcb containing such sensors. They based the spacing on the hall sensors on the number of stators, so the sensors are 40° apart (80° total span). I've been assembling the hall pcbs to motors trying to find the "sweet spot" to get decent performance, but didn't get great results. Came to find that none of our motor/hall assemblies work well. So I dug into it a bit and found references saying the hall spacing is based on the number of poles, not stators. They report the spacing is based on the electrical angle of the phase voltage, which makes sense.
They say the spacing is 120°/PP, where PP = number of pole pairs. This calcs a spacing of ~5.7° between each sensor. Due to the 3 phase, the spacing can also be a multiple of 4. So a spacing of ~45.7° is also acceptable.
I did some observations of phase vs hall signal on an oscope and can clearly see if I align one phase to the hall the other phases don't line up accordingly. So I'm here to see if anyone can provide helpful feedback. This is my first time working with BLDC motors so it's hard for me to make an independent judgement. Let me know if you have any thoughts or if I can provide more info, and a big thank you in advance!
They say the spacing is 120°/PP, where PP = number of pole pairs. This calcs a spacing of ~5.7° between each sensor. Due to the 3 phase, the spacing can also be a multiple of 4. So a spacing of ~45.7° is also acceptable.
I did some observations of phase vs hall signal on an oscope and can clearly see if I align one phase to the hall the other phases don't line up accordingly. So I'm here to see if anyone can provide helpful feedback. This is my first time working with BLDC motors so it's hard for me to make an independent judgement. Let me know if you have any thoughts or if I can provide more info, and a big thank you in advance!
