PIDE vs PID in CLX for speed control?

[Paul351W]

I have an application using an eddy current coupling to transmit torque from an AC motor to a brake module. The coupling is needed so the AC motor can be disconnected from the drive line for inertia reasons during stop tests.

Due to the eddy coupling characteristics, there will be a large speed delta between input and output when load is applied. The operator wants to maintain output speed while load is applied, so I will have to ramp up the input speed as the coupling begins to slip under load.

Question is: which would be better for this application, a ladder logic PID instruction, or the function block PIDE instruction? All I've ever used the PIDE for is some pressure control, and that was mostly feed-forward activated.

 

[rdrast]

In almost all circumstances, I prefer the PID instruction. The PIDE is overly complicated, and has occasional issues.

Eddy current? Wow... it's been a long time.

 

[Paul351W]

Yeah, they had the coupling in use on a similar test previously so they decided to use it again.

I wasn't sure if the alternative PID formula that the PIDE uses would provide better performance or not, as I've never seen any comparisons between the two on the same circuit. It would save me adding a function block routine to the program if I just used the regular PID...

 

[kamenges]

I don't think the algorithm at the heart of the PIDE is any better or worse than that in the PID. The PIDE just gives you alot more bells and whistles. I think they tried to make one instruction that could do everything. So, as rdrast said, she be a complicated beast.

Keith