I am designing a control strategy for an AC(induction) 3-phase motor fan in an HVAC air handling unit for pressure control inside the ductwork.
The plan is to use a PID algorithm for the pressure control, by varying the fan speed, however I am quite confused if it'll work on start-up.
If the (Setpoint-Measured pressure) is high enough on start-up, which should always be, the output fan speed will be at 100% at start. This means that the system will start the motor with a 100% motor speed(high frequency). I was wondering if starting the motor with a high frequency AC would provide enough torque in order for the motor to start moving.
So my question is if the PID algorithm is sufficient or do I need to provide a slow acceleration at start-up(starting from 50Hz) and then switching to PID when the fan is accelerated enough.