PID controller tuning, cannot linearize the plant and error.

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Hi, hope your doing well
need to tune the PID controller but I am facing a lot of errors, like linearizing failors, and this error :
"The Simulink model DABClosedLoop could not be linearized when downsampling unstable poles with large magnitude with a sample time of 1e-07 to 0.0001. Try decreasing the target sampling time."
The Simulink model is attached.
Please help and thanks

Accepted Answer

Zhao Wang
Zhao Wang on 21 Apr 2022
The model would be linearized while lauhcing the PID Tuner from the PID Controller block's parameters dialog. The attached model, is a switching model with PWM signals driving the IGBT/Diodes. Because of the discontinuities in the model, linearization would error out or maybe linearize to zero. As a result, tuning the PID controller is not possible based on this default linearization result.
To workaround this issue, there are two possible approaches:
  1. Use an average-value model to replace the switching circuit model using the same component parameters. This would allow linearization to obtain a meaningful result for controller tuning.
  2. Keep the switching circuit and conduct frequency response estimation to obtain a linear plant model. The frequency response estimation result can then be loaded into the PID Tuner for controller tuning.

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