I'm working on a project about controlling Brush-less DC Motor using PI(Proportional Integral) Close Loop Speed Control Method.
3 Phases Motor is driven by 6 MOSFETs, Rotor speed is sensed and feedback to the control IC, this IC will compare the reference speed (target speed) with the sensed speed and adjust the control of the 6 MOSFETs.
Schematic is as below:
Calculation and controlling can be done inside the IC itself, but I want to know what signal the PI Close Loop Speed Control will control to archive the target speed? Eg: when rotor speed is lower than ref speed, the controller will increase the Duty cycle of PWM or will it increase the phase switching frequency?
Thank you all for reading.