On 06/04/2013 01:00 AM, andy pugh wrote: > On 3 June 2013 20:41, Viesturs Lācis <[email protected]> wrote: > >> Did You try "h" mode? For me it was the toughest to find correct Hall >> pattern. Later on going to "qh" was relatively easy. > > PCW has pointed out to me that some of the Hall patterns are not > actually valid, as they don't follow a progressive sequence. > However, it is a bit late to go changing them now… > > Checking the bldc.N.hall-error pin is a good idea. If that shows > "true" then no matter if the motor is spinning, the hall pattern is > wrong. > > Try 15 first. >
I tried all patterns and found that patterns 3 and 30 are good, just different directions. I found that hall sensors are not aligned. I managed to count encoder offset with my two channel DSO today, rotating motor with a drill and measuring back-emf between two phases, and one encoder channel, triggering on encoder index. Hall should trigger when back-emf measured between two phases crosses zero. And this correlates to the setting I got trying different encoder-offset values yesterday. Strange thing is that when using qi mode with this offset I get very different velocities in different directions. I am changin bldc.n.value to 0.25 and -0.25 in halshow, no PID yet. Now I can see that qi mode is quite good. And I want to use it. I am even thinking of making my own electronics for measuring this offset. There are reasons why I don't want to use hall sensors: 1. hall sensors and encoders both do not fit in the enclosure of my motors 2. less wires 3. hall sensors are not manufacturer aligned 4. more spare inputs on MESA card 5. possibility to use any BLDC motor with simple encoder What reasons are for using hall sensors? As I understand, commutation goes from software, which means there is no difference between qi or qh modes in reaction time. I was planning to spin my 8-pole BLDC motors up to 3000rpm. This means 5ms every electric cycle. When using 1ms servo period, this may be not very nice.. What do you think? I think I will need to try smaller servo periods. I thought all this hostmot2 and bldc on 5i23 + 7i39 commutates in hardware (I think this is possible). I am disappointed a bit. ------------------------------------------------------------------------------ How ServiceNow helps IT people transform IT departments: 1. A cloud service to automate IT design, transition and operations 2. Dashboards that offer high-level views of enterprise services 3. A single system of record for all IT processes http://p.sf.net/sfu/servicenow-d2d-j _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
