[SOLVED] PI value to duty cycle

[ashugtiwari]

Hello All,
Im currently working on DC motor control project and have designed one PI controller to control its speed and current. The PI controller takes the difference between actual and reference speed and finds the error and then using simple z-domain PI controller calculations I generate PI value. Now, the question is how to convert the PI value into the % duty cycle value for controlling DC motor speed?

Please reply. Thanks for answers.

Ashutosh

 

[ashugtiwari]

I found the answer.
The PI calculations should be done in one of the format like Q15 i.e. 16 bit integer format, so all the input and output values are in same format. Then output of PI can be scaled to PWM resolution easily by a simple scalar multiplier.