Hi Kirk, The answer is below. Mariss, puts a lot into the public domain. That way it's prior art if anyone tries to patent it.
------------------------------- The drive generates a reference voltage proportional to speed. This voltage is sensed by an offset/gain circuit that becomes linear (from 0V) at 4 revs a sec and goes non-linear again (clamps at 3.3V) at 6 revs a second. It's output analog ORs with the sine-cosine reference. The sine-cosine reference is always there, it is simply swamped by the ORed full-step morph signal. So big deal, decel to zero instantly. 2 milliseconds later the reference reverts from full-step to sin-cos. Enjoy the 141% torque bump while it lasts for the 2mS. It's all analog.:-) ---------------------------------- Cheers, Peter On 3/05/2012 1:45 AM, Kirk Wallace wrote: > On Wed, 2012-05-02 at 10:19 -0500, Jon Elson wrote: > ... snip >> It just seems to me that when the motor inductance causes the winding >> current to lag >> behind the current command from the microstep sine wave, the current control >> logic will automatically become the same as a full-step drive, with no >> special >> function at all required. But, I admit, I have not extracted the >> schematic of >> the drive to figure out if there is anything extra there. >> >> Jon > > I suspect the magic is in the Xilinx chip programming, so we'll probably > never know what the magic is. I'd like to play with a couple of Pico PWM > amps on one of my Shizuoka steppers and drive them with FPGA PWM. There > would not be any current feedback to work with unless I add a pair of > ADC's though. > > On the other hand it might be more productive to start work on fitting > some brushless motors. -- ----------------------------------------------------------------------------- eStore: http://www.homanndesigns.com/store Web : http://www.homanndesigns.com ModIO - Modbus Interface Unit email : pe...@homanndesigns.com DigiSpeed - Isolated 10Vdc I/F Phone : +61 421 601 665 TurboTaig - Taig Mill Upgrade board ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
