| Title |
Optimization of a PI Controller Design for an Oil Cooler System with a Variable Rotating Speed Compressor |
| Authors |
Taeeun Kwon ; Taeyoung Jeong ; Seokkwon Jeong |
| DOI |
http://dx.doi.org/10.6110/KJACR.2016.28.12.502 |
| Keywords |
최적 PI 제어기 ; 오일쿨러 ; 가변속 압축기 ; 절대 오차 시간곱 적분 ; 온도제어 Optimized PI controller ; Oil cooler ; Variable rotating speed compressor ; ITAE(Integral of Time-weighted Absolute Error) ; Temperature control |
| Abstract |
An optimized PI controller design method is presented to promote the control performance of an oil cooler system for high precision machine tools. First, a transfer function model of the oil cooler system with a variable rotating speed compressor was obtained by the perturbation method as the first order system with a negligible dead time. Then, the closed-loop control system was described as the second order system with a zero. Its dynamic behaviors are mostly governed by characteristic parameters, the damping ratio, and the natural frequency which is incorporated in PI gains. Next, an optimum integral of the time-weighted absolute error (ITAE) criterion was applied to the second order system. The characteristic parameters can be determined by the given design specifications, percent overshoots and settling times and comparisons with the ITAE criterion. Hence, the PI gains were plainly identified in a deterministic way. Finally, the PI gains were fine-tuned to obtain desirable dynamics in real systems, considering the zero effect and parameter variations. The validity of the proposed method was proven by computer simulations and real experiments for selected cases. |