topic Re: 3 phase brushless motor using "zero crossing phase comparator" in S12ZVM in S12 / MagniV Microcontrollers

3 phase brushless motor using "zero crossing phase comparator" in S12ZVM

ryoishiyama — Sun, 11 Feb 2018 07:52:02 GMT

　I would like to see application notes or information conforming thereto that drives a 3 phase brushless motor using "zero crossing phase comparator" in S12ZVM.
In An 4704, ADC 0 or ADC 1 is used for zero cross detection of BEMF, but I would like to use "zero crossing phase comparator".
Will you show application notes as a hint or information similar to that?

Re: 3 phase brushless motor using "zero crossing phase comparator" in S12ZVM

pachamatej — Wed, 14 Feb 2018 10:00:31 GMT

Hello,

I'm afraid there is no application note on that.

The phase comparators are not designed to detect the BEMF zerocrossing. There is no interrupt flag, which would do the magic. We don't recommend it, however if you are still likely to try it, the hint would be to periodically look for a change to the GDUSTAT register (the phase status bits). Such approach would be high CPU load demanding - just checking periodically for the change for a relatively long period of time. Therefore, we prefer to do it using software calculation. Using this software calculation is not too much CPU load demanding since it is synchronized with ADC sampling and it also gives you a certain level of flexibility.

Regards

Matej

Re: 3 phase brushless motor using "zero crossing phase comparator" in S12ZVM

ryoishiyama — Sat, 17 Feb 2018 11:40:58 GMT

Hello,

Thank you for useful technical information.
As you advised, I would like to drive the motor using the ADC and its interrupts.
I think the S12ZVM is a very useful microcomputer.

Best regards

Ryo