I have done this before, but always looking for a better way. The application is: I have 3 AC inverters operating in open loop vector mode. I know the answer, but is cost related. Using encoders, or servos would be my way to. However it is what it is. I need to ramp 3 VFD's. One will always run a the speed set point the other 2 (followers) will be at an adjustable %, plus or minus, of the speed setpoint. I also have adjustmnet for the Accel and Decel time. I calculate the ramp rate base on the speed set point and the accel/decel times on a time base of 100ms. The problem I have always had is the followers do not get to 0 speed at the same time the main does. I have a solution I am working on and will share at a later date. This post is already long. I am just looking for ideas to see how they compare to mine.
Thanks
Thanks