Maximum RPM consideration.

alanlai1 · ‎2005-04-12

Posted on April 12, 2005 at 10:39

alanlai1 · ‎2011-05-17

Posted on May 17, 2011 at 10:18

Recently, we visited a customer, and promoted ST7MC for customer RF control model-plane application.

Customer implied the application need to rotate the motor 30000 rpm; do we have any limitation in high speed rotation? Can we still use back-EMF to sense the position? / Hall sensor? Which one is better? Should I have some other things to concern in this case?

Thanks for your suggestion~

gaetano · ‎2011-05-17

Posted on May 17, 2011 at 10:18

Hello,

simply speaking, at 30000 rpm, a one pair pole motor have a step duration of 333us (when driven in 6 step mode).

Using ST sampling method, with a PWM of 50KHz, you have 16 samples for BEMF detection: a value that can be considered acceptable. Otherwise, with the alternative sampling method (during PWM ON time) you can sample at higher frequency (tipical at 1MHz).

So, regarding the speed you are reaching, from theoretical point of view, not particular problems should occur.

Best regards,

Tanio