This paper, aiming at the large time-delay system, firstly introduces the design and parameter tuning methods of ZN-PID and IMC-PID controller. Then it derives the parameter expression of IMC-PID respectively based on one order Pade approximation and all-pole approximation. At last it does the simulation both in model match and mismatch cases and analyzes the frequency domain characteristic of the control system. The simulation results show that the IMC-PID controller, especially suitable for the model mismatch, outperforms the traditional PID in regulation, robustness and anti-interference. Moreover, the step response characteristic and stability of the all-pole approximation is better than one order Pade approximation when coping with the time-delay. http://www.sj-ce.org/paperInfo.aspx?ID=1190
