Yes, at high enough PWM frequency you can pretend the motor is seeing variable voltage DC. his is true for all practical purposes.
This is a quote from the VNH3SP30 data sheet: *The speed of the motor can becontrolled in all possible conditions by the PWMup to 10 kHz. In all cases, a low level state on thePWM pin will turn off both the LSA and LSBswitches. When PWM rises to a high level, LSA orLSB turn on again depending on the input pinstate.* reading the above there is nothing space about 50% duty cycle. It is just roughly half-speed. Me disagreement was that the PWM signal is never used to reverse the voltage applied to the motor My suggestion is just rad the data sheet and don't try to fix problems that don't exist or come up with new solutions Polulu has an Arduino driver for this VNH**** chips that is not great bit does show how to use the chip to go forward and back at different speeds and to apply the "brakes" Not directly usable but you can cut and paste these examples https://github.com/pololu/dual-vnh5019-motor-shield On Sun, Oct 18, 2020 at 3:09 AM Nicklas SB Karlsson <nk@nksb.online> wrote: > > The theory is that if the PWM signal is high the H-Bridge is switched to > > >> say turn the motor clockwise. If the PWM signal is low > >>>> the H-Bridge is switch to turn the motor counter clockwise. Therefore > >> with 50% the motor is first asked to turn one way and then > >>>> the other. That results in the motor essentially being locked in > place. > > > > The above is not the way it works. No one would design anything like > > that. But let's say you did. What would happen? The motor would > > vibrate and slowly rotate and have close to zero torque > > It does work with high enough switching frequency because motor > inductance average out applied voltage to a more or less triangular > current over one switching period. With high enough switching frequency > current ripple is low enough average is more or less equal to analog > voltage and current. > > ... > > Nicklas Karlsson > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
