| Title |
Auto-tuning of PID Gain by ON/OFF Operation of a Variable Speed Refrigeration System |
| Authors |
Tae Hoon Kim ; Seok Kwon Jeong |
| DOI |
https://doi.org/10.6110/KJACR.2024.36.1.31 |
| Keywords |
자동 튜닝; 다변수 시스템; ON/OFF 운전; PID 제어; VSRS; 가변속 냉동시스템 Auto-tuning; Multi-variable system; ON/OFF operation; Proportional-integral-derivative control; Variable speed refrigeration system |
| Abstract |
Proportional-integral-derivative (PID) controllers are widely used for industrial process control due to their simple design and excellent control performance. PID gains are generally designed based on the transfer function models of plants. However, it is very difficult to obtain a low-dimensional linear approximation model of a variable speed refrigeration system (VSRS) because of its inherent nonlinearity and high-order dynamic characteristics. In addition, obtaining desirable control performance of model-independent PID gain tuning methods is very difficult. Therefore, robust auto-tuning and PID control of a VSRS, which is a multi-variable system with strong inherent nonlinearity, are described in this paper. In particular, the proposed method can be applied to actual systems affected by thermal noise and thermal load with conventional ON/OFF operation. In addition, in the case of a multi-variable system, the operating conditions of the remaining variables were clearly revealed when auto-tuning one variable. The proposed method proved its validity through experiments, and stability and reproducibility were confirmed by analyzing pole position and a Bode diagram. |