Hello everyone and thanks in advance for your support :)
I'm developing a unconventional Sensorless BLDC motor (See attached pictures)
Have I overlooked some setting that might allow my design to hit it's target RPM?
I have limited access to resources like laminated stators as many do for prototyping. So do to design size, weight constraints and material resources I'm using what I have on hand and is readily available online and that I'm able to fabricate using only basic hand tools and a drill press. I purchased the above subject kit and have had encouraging success but I'm unable to hit my target RPM's of approximately 4-5k. I'm no expert and have no prior technical training in this area, but lets not let that keep me from exploring the possibilities... :)
I have two plywood discs that face each other one housing the 1/2" x 1/2" cylinder N52 rare earth magnets (12 originally now 6) and the other 26 gauge copper magnet wire coils (9 w/air core) and about 350 turns each. With 12 (mag) and 9 (coils) I was able to get a little better than 1400+ RPM and I increased that by another 300+ RPM to about 1700+ by tweaking the "Advanced Tab" 'Field Weakening' set to (-0.3) and 'SVM Modulation' set to 2.00.
I then tried adding steel cores (I had a length of 1/2" dia. grounding rod) to the coils and found that that decreased the speed to about 450 RPM, I now know that only laminated electric or transformer steel must be used, but again I'm trying to watch the overall weight and air cores would be my first choice.
I then removed the iron cores and repositioned the magnets placing 2 same poles next to each other then alternating the poled pairs i.e, NN, SS, NN, SS, NN, SS. This actually did spin during identification but at about 45% it failed to identify the motor. I then bridged the poled pairs with a piece of transformer steel laminate thinking the bridge might merge the two poles together into one pole, didn't help :( I'm thinking the size of magnet area vs coil area might be the issue or the fact that it was sensing double like kind poles next to each other???
I then removed every other magnet leaving just six figuring this would speed up the sequencing and it did :) Now I achieved 2100+ RPM and with advanced tab tweaking I got it up to 2400+ (see pics), but still far from my target.
Outside of a conventional BLDC stator/magnet configuration, anyone have any expert advice or suggestions?
Are there any resources that that give examples of motor stator and magnet configurations for speed?
I'm also in need of an individual to help me design the PCB that will be needed to drive this design to maintain defined speed and other requirements not discussed here. Anyone???
Thanks, Bruce