pid controller block parameter

hello, my name is Nitin. I am undergraduate student. I am trying to design ac(100) to dc(200) converter using 4 IGBT connected in bridge. That boost converter is working but when I am taking feedback from output and compared with reference Voltage and given to PID(proportional and Integral) to get the output voltage regulated to 200. It is taking time to regulate as well as it is not even regulating to 200V. I want to know how to adjust the value of PID. I have read all the study material still not able to solve the problem. specification are.. vin=100,50hz vout=200 capacitor value Cout =10000uf inductor value Lin =69uH resistor Rout =10ohm. Vref= 0.5 PWM frequency =4khz right now PID values are P= 0.65,I=2,D=.001,N=100.. please help...............I don't know how to add .mdl file over here that's why I have given all the specification.

[Ryan G]

Are you able to use the 'tune' button in the PID block? Does your system linearize well? This can significantly simplify the process.

[nitin]

thanks for reply.... sir, whenever I am trying to tune the model it is giving me error and that is

The plant model in the PID loop linearizes to zero, and therefore cannot be used in PID controller design. This problem occurs when one or more blocks in the PID loop have zero gain or the feedback loop is not physically closed. Click "Continue" to launch the PID Tuner and obtain a new plant model in the "Obtain plant model" dialog. Click "Cancel" to return to the PID Controller block dialog. For more information, see the Simulink Control Design documentation.

and when I am clicking on continue button it is adjusting the value of P=0 and I = -1. after auto tuning also the output is not coming. should I sent u .mdl file so that it will be easy for you to help me. sorry but I don't know how to add .mdl file over here.

thanks once again....... I am very much new to Simulink ... please help.... nitin

[Ishu J]

hello sir, I have the same doubt while tuning PID controller. Also in my simulink i have two controllers so how to tune those?

Answer 1

[Arkadiy Turevskiy]

Hello Nitin,

PID Tuner works by linearizing the model. It then uses the linearized model to come up with the gains. It is very common to run into zero linearization issue when working with electrical systems like you are doing. Often this happens when pwm is used.

Often times this problems can be solved by linearizing the model at a different operating point than the default one (by default the model is linearized at simulation time 0). This and other suggestions are explained in detail in the documentation here.

You may also find this video and this webinar useful.

HTH.

Arkadiy