Precise temperature tracking control for refrigeration systems using fuzzy self-tuning PID parameters

Industrial refrigeration systems are complex control plants characterized by strong nonlinearity, significant time delays and susceptibility to random load disturbances. Conventional PID controllers with fixed parameters often encounter difficulties in maintaining stable temperatures when operating points shift or under the influence of external disturbances, such as heat load fluctuations. This paper proposes a Fuzzy Self-Tuning PID controller design for cold storage temperature control. The fuzzy algorithm is employed to tune the three parameters (Kp,Ki,Kd) and $K_d$ online, based on the error and the rate of change of the temperature error. Simulation results in MATLAB/Simulink demonstrate that the proposed controller achieves faster response times, reduced overshoot, and significantly better disturbance rejection capability compared to the traditional PID controller.