Pid tuning for analog dimming for led driver

[edwin.sun]

Hi,

Really fascinating pid tuner.

I am trying to tune a pid controller used to constant current led driver to control led brightness (you change voltage/dac to accomplish current setpoint) (so control variable is the voltage or dac and process output is the measured current).

I have tried application however I get gains and integral are quite high that system becomes unstable.

I don’t know if this pid tuner is inherently designed for a slower system like temperature control (as I am passing in impulse of change from voltage to another) or if I am passing in the wrong values. I am open to any guidance as I am learning more into control theory.

For example, here is an example of the impulse. In this snippet. with dac value = 42000 (dac value ranges from 0-65535) with SP =585 (ma) and second column reads the measured current (ma).
0, 0, 0.000000, 0.200000, 0.000000, 42000
0, 0, 0.000000, 0.200000, 0.000000, 42000
0, 0, 0.000000, 0.200000, 0.000000, 42000
585, 0, 0.000000, 0.200000, 0.000000, 42000
585, 0, 0.000000, 0.200000, 0.000000, 37500
585, 38, 0.000000, 0.200000, 0.000000, 37500
585, 666, 0.000000, 0.200000, 0.000000, 37500

Sincerely,
Edwin

[pidtuner]

It is likely that you are passing the wrong values, you need to pass exactly what comes in and what comes out of the PID block. Refer to this guide for more details:
https://github.com/pidtuner/pidtuner.github.io/blob/master/assets/doc/PID%20Tuner.pdf

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