Integrating Flywheel PID

My main reason for asking this question is to address the PID loop for our flywheel.

For some context, flyWheelPID is part of a PID class I use for all my different controllers. The calculate simply returns the correction with the different kP, kI and kD parameters. in the second line of the void, rpm is being divided by 4200 since that’s the top speed of the flywheel and then multiplied by 12000 to get the voltage for the desired voltage. I was wondering if this approach was correct, or if there was a better way to do it,