On 17 January 2011 05:20, Kirk Wallace <kwall...@wallacecompany.com> wrote: > I'm a little confused about the bldc comps. My study of bldc so far > indicates that the top and bottom of three half-bridges need to to be > controlled, so I though the comps would need six outputs instead of the > three (3 digital top, 3 PWM bottom). What am I missing?
The currently-released bldc_hall and the half-released bldc_sine are aimed specifically at controlling the Mesa card three-phase PWM generator. The input is three float amplitudes, the output is 6 bit-level PWM signals. Except in the case of the 7i39 where the output is three bit-level PWM signals and on-board cleverness does the rest. The not-yet-released bldc (no suffix) component provides the output as three or six float or bit signals for either 6-step (trapezoidal) or sinusoidal drive. It does not (as yet) output any PWM signals directly, though that is something I have considered adding. With trapezoidal drive there are no adjacent steps where the high and low side driver states both change, so there is no danger of shoot-through with non-synchronised PWM signals, so in 6-step mode you could use ordinary pwmgens on the low-side drivers enabled from the bldc comp in hTB6 (hall input, 6 bit outputs, forced trapezoidal) or qBT6 (encoder input, 6 bit outputs, forced trapezoidal) modes. -- atp "Torque wrenches are for the obedience of fools and the guidance of wise men" ------------------------------------------------------------------------------ Special Offer-- Download ArcSight Logger for FREE (a $49 USD value)! Finally, a world-class log management solution at an even better price-free! Download using promo code Free_Logger_4_Dev2Dev. Offer expires February 28th, so secure your free ArcSight Logger TODAY! http://p.sf.net/sfu/arcsight-sfd2d _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
