On Thursday 15 October 2020 17:17:59 Thaddeus Waldner wrote: > The reactance and inductance questions are above my pay grade and I’d > be happy to hear someone explain it. :) I use these for robotics class > in place of the old BJT L298, which are optimistically rated for 2 > amps but have more than 2v drop at much less than that current. > > Maybe I don’t understand your comment but I’m pretty sure that a 50% > duty cycle PWM waveform will run the motor at half-voltage.
What I had in mind was a quicker than hal's logic can do it, as hals direction reversal by controlling the inA and inB inputs will be plenty slow enough to have it oscillate possibly uncontrollably. This may not be the ideal device, we'll have to see once they arrive, which could be as early as Monday. What I have in mind is basically a 400 watt or more, class D audio amplifier. Maybe I've gone looking using the wrong search terms. Yes and with very similar pricing, a dual 2kw is $25. I'm thinking... > You command the direction with INa and INb according to the Truth > Table. The PWM signal will then switch either the A or B low-side > FETs, depending on the INa/INb configuration. > > > It would appear that when enabled, and lets say with a pwm frequency > > near the top of the 10khz range, that a 50% duty cycle pwm waveform > > would be the equ of a balanced, at rest servo, so my first question > > is how much additional inductance in series with the motors leakage > > reactance will be needed to protect the chip from the current surges > > at the pwm waveforms transition points? > > > > My hal file will obviously need to stage an initial enable at the > > 50% duty points, then let the pid output thru. > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
