Gene Heskett wrote: > On Wednesday 06 February 2008, Alex Joni wrote: > >>>These introduce a 50 ms delay in >>>the feedback signal. Is this acceptable? I think, probably not. >>> My question is this. Do I need to install encoders on the motors? >>> Questions, thoughts, comments welcome. >> >>50msec is waay too much, but reading the >>http://www.amci.com/pdfs/accessories/RD141S_rev_1.0.pdf >>I can't find it... are you sure it wasn't 50ns ? >> > > I doubt if its that fast. With a 5khz carrier, I'd assume it takes a full > cycle to come up with an angle and then convert, and the angle will take .2 > milliseconds if its done in a single full cycle of the carrier. > > Or do I not understand how these work? I've studied the Analog Devices units. They have a tracking PLL that attempts to track the velocity of the resolver. So, it doesn't quite do a complete conversion from scratch every cycle (or half-cycle) of the sensor excitation. It is more like it generates an estimate of position from the PLL and then refines the error. Also, using the AD chip, you can set the frequency to whatever you want. My guess is that AMTI clunker has a PIC micro with A/D in it, and not much else, and costs them $15 to make. I didn't see what Stuart had to pay for them. But, if that 50 ms lag is correct, they are of VERY limited usefulness.
Jon ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
