1 / 21

UNITRONICS

UNITRONICS. D. P. roportional. I. ntegral. erivative. 1 /13. PID – What's our goal? . The PID function uses system feedback to continuously control a dynamic process. The purpose of PID control is to keep a process running as close as possible to a desired Set Point.

khuyen
Download Presentation

UNITRONICS

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. UNITRONICS D P roportional I ntegral erivative 1/13

  2. PID – What's our goal? The PID function uses system feedback to continuously control a dynamic process. The purpose of PID control is to keep a process running as close as possible to a desired Set Point.

  3. ON – OFF control • Switches the power ON and OFF (0% - 100%) • Pros: • Easy to understand, easy to perform. • Cons: • Not precise. In some systems "waves" of over and undershoots can reach 10-20% of PV. • In some fast systems is impossible of all.

  4. What's PID? Mathematical process, which is calculating in each moment the energy need by the system to achieve the goal in the best way.

  5. What's PID? PID means: Proportional + Integral + Derivative control CV = CV (P) + CV(I) + CV(D)

  6. What's PID? • Proportional control is leading. • The control can be: • P control only • PI control • PD control • Full PID control

  7. Proportional control A band around SP is defined – in percents of PV range. Out of proportional band CV is always 100% and no calculations are done. Proportional error is 100% on the border of PB. Proportional error is 0% at SP. P-control outputs CV(P) value that is in: Direct linear proportion to the size of the Error value.

  8. Proportional control • Simple – easy to understand, easy to program even in ladder • Cons: • Never reach Set point!

  9. Integral control The integral time you set is the amount of time, as calculated by the controller, required to bring the process to Set Point. According to the delay, Integral action adds value to this, calculated by Proportional action. Integral value is accumulated with the time.

  10. Integral action CV = CV(P) + CV(I) On set point – CV(P) = 0  CV = CV(I)

  11. Derivative action Derivative action responds to the rate and direction of change in the Error. This means that a fast change in error causes a strong response from the controller.

  12. PID control in Vision • Functional block. • Many PID loops can be controlled simultaneously. • Fully independent loops. • Large scale of inputs and outputs. • Integrated in full system logic.

  13. PID control in Vision Advanced control functions: • Ramp and soak. • Full step programmer. • Bumpless control. • Cascade control.

  14. PID control in Vision • Configurating FB PID: • With one scan condition (mostly Power up SB2) • On subroutine, which is always scanned (recommended Main routine!)

  15. PID parameters Let's open configuration block:

  16. Why Autotune? Each system has its own set of P, I, D and St values. Finding "manually" these parameters needs experience and time. Autotune learns the system and calculates the optimal parameters for it.

  17. Autotune – how it works? Autotune runs ON-Off cycles According to the "wave" of overshoot, the base PID parameters are calculated . Number of cycles 1 ~ 3 is set in Autotune module. More cycles – more precise result, but longer process.

  18. Autotune – how it works?

  19. FB PID – Advanced functions • Pause Integral and Derivative action • Read & Force integral Error • Read Control components

  20. PID Server • PID server is ideal tool for understanding, learning and debug PID process! • You can use it: • To view process. • To Log it. • To Autotune it – up op to 8 cycles. • It's part of VisiLogic or independent tool. FREE Of Charge

  21. UNITRONICS Thank You 21/13

More Related