Posted on May 17, 2011 at 10:16 Integral and proportional coefficients are parameters of the regulation.
The regulation is used in order to maintain a predefined speed even with a variable/unknown motor load.
On the ST72141, the regulation is done by software.
That means:
- you need a regulation routine to perform the control
- the integral and proportional parameters are built in your program
The selection of those parameters may be a difficult task, that implie a lot of testing. The parameters will depend on the application (system inertia, reaction time needed...)
this is the way I usually proceed:
- start with a low proportional/integral parameters
- increase the proportional parameter until you reach a good reaction time for your application.
- Avoid a coefficient too high that would create oscillations.
- When you reach a correct value, the error on the speed is usually too big
- then you can increase the integral value to reduce the error.
- again a parameter too high will generate oscillations
Regarding the delay coefficient:
this parameter controls the phase shift between the back-EMF voltage and the current waveform. It therefore controls the efficiency of the motor.
It is indeed a very important parameter! Set it to 16/32 at low speed and decrease this as the speed goes up. An erroneous value at low speed may prevent themotor from running.
I hope it helps!
Max
