On Wednesday, March 09, 2011 11:26:57 AM Klemen Dovrtel did opine: > Hello everybody, > > Has anybody ever made a PWM triac control hal module/component or > assemble one from existing hal modules/components? There should be one > input signal for zero cross detector and one output signal to control > the triac gate. > > If not, do you think this can this be easily done using hal? > > Best Regards > Klemen > The two reasons I would not consider using a triac in a servo are:
1 the triac needs a zero crossing of several microseconds duration in order to reliably turn off. 2. you are married to the powerline frequency for updating the firing angle because once fired its going to be on for the rest of that powerline half cycle. That is too slow for decent servo response. One might be able to raise the operating frequency to 400 hz with a motor generator but at 400 hz, I'd question the safety time to get a good shutoff at the zero crossing since the available reset time is much shorter at 400 hz. This is why I'm personally in favor of a pwm driven hexfet controller, you can, with adequate drive, turn one of them on or off in much less than a microsecond thereby reducing the ohmic losses during the transition time, which in turn allows it do so at 15K-50K times a second without excessive heating, bringing real time speed control into the smaller horsepower world. My spindle speed is so stiff I gave up and put an ammeter in so I could see how hard it was working, it cannot be heard to slow before the fuse clears. And this is the controller that came in my micromill, with only the hexfet replaced because it wasn't adequately rated in the first place. This style of controller can be scaled up to 10 or more kw. But it is not a position servo, capable of holding a set position like a real servo can. -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) <http://tinyurl.com/ddg5bz> The world is full of people who have never, since childhood, met an open doorway with an open mind. -- E.B. White ------------------------------------------------------------------------------ Colocation vs. Managed Hosting A question and answer guide to determining the best fit for your organization - today and in the future. http://p.sf.net/sfu/internap-sfd2d _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
