On Sat, Dec 22, 2012 at 6:17 PM, Steve Stallings <[email protected]>wrote:
> Why is a bare H-bridge > driven with PWM not equivalent to voltage mode? I thought > the duty cycle of a PWM drive was effectively integrated > by the inductance of the motor such that the percent duty > cycle was equivalent to percentage of bus voltage on the > H-bridge as far as the motor was concerned. > > They are exactly the same and your thought is correct. The only differences: In a digital pwm control there is a z^-1 delay (= linear phase shift increasing w/ freq.) In an analog pwm controller w/ a voltage compared to a ramp the delay approaches z^0.5. There is no such delay in an linear amplifier (z^0) The motor resistance and inductance form a pole in either an analog linear voltage amp or a pwm'ed one. Stephen Dubovsky ------------------------------------------------------------------------------ LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial Remotely access PCs and mobile devices and provide instant support Improve your efficiency, and focus on delivering more value-add services Discover what IT Professionals Know. Rescue delivers http://p.sf.net/sfu/logmein_12329d2d _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
