Temperature control: the trend is showing an increasing trend. How should the PID be adjusted?

By reducing P and increasing I, temperature regulation can also be used to increase D appropriately

The forward and reverse action of your regulator isn’t reversed, is it? If it isn’t reversed, then adjust it as mentioned above.

First, determine whether the direction of action of your regulator is correct. Then, try to adjust the PID parameters when the process is stable (for example, when material intake and output are stable), as this reduces interference factors and makes it easier to set the PID parameters. First, look at the curve; when overshoot is high, reduce P ； Looking at the curve further ahead, since there are more oscillations, reduce the integration time. For temperature control, differential control should be used, with the differential time being increased gradually. It’s better to adjust the PID values one by one, as this makes it easier to make judgments. It’s not possible to tune PID parameters properly that quickly, because it’s often difficult to determine exactly what the interfering factors are; patience is required, along with gradual analysis and summarization.

The original poster didn’t describe it clearly, so I can only guess. ““The trend is becoming more and more pronounced” – is it moving further and further away from the set value? In that case, I think no negative feedback has been established; it’s positive feedback. Let’s try changing the positive and negative actions of the regulator and see...

I’m sorry, what I meant is that the positive and negative values are becoming larger and larger.

The temperature has a large capacity lag, so the PID needs to include a derivative term. Add a dot to the derivative

This post was last edited by ybcity on 2015-6-2 06:25. Analyze the control loops and regulatory elements; use smaller loops for adjustments wherever possible, as this can reduce the likelihood of large fluctuations in the system. Reduce the magnitude of each adjustment and increase the frequency of adjustments; once stability is achieved, gradually reduce the frequency of adjustments

Hello, isn’t it the case that \"the smaller the P-value, the stronger its regulatory effect (the greater the adjustment magnitude on MV); if this effect is too strong, it can cause the system to over-activate or under-activate, leading to frequent fluctuations, and as a result PV experiences frequent changes, or even becomes unstable\"? Why is there overshoot? Why should P be reduced?