PPPS for repurposed refrigerated spaces where the refrig is too big/cold/aggressive, and assuming we can't get it by adjusting valves etc:
I'm going to have to deliver the refrig in a series of pulses to minimise temp overshoot (actually undershoot).
I will need to approximate the pulse size (due to delay in response time).
I'm trying not to short-cycle the gear.
So, I will deliver a pulse as required, and the duration of the pulse is some reciprocal of the temp rise time: fast rise, bigger pulse.
I will impose a minimum pulse value (since a pulse below a certain value provides no refrigeration)
and probably a max value to keep things toned down through door openings etc.
And I will impose a minimum pulse to pulse time to avoid short cycling.
An alternative to this is to have the pulses at set intervals, with the pulse width proportional to the the temperature error (actual temp (PV) minus setpoint (SV)).