A tuning method based on performance optimization within stability region for the cascade loop controller of high-precision temperature control systems

The fluid precision temperature control system is essential for reducing optical errors and improving wafer stage positioning in semiconductor manufacturing. Temperature control strategies are key to system precision but face challenges due to large inertia, time delays, and disturbances. Cascade control strategies are widely applied due to their effectiveness in addressing inertia and time delay; however, parameter tuning for cascade controllers still lacks effective methods. Existing tuning methods frequently lead to overly aggressive parameters that cause oscillations, and it is difficult to determine an appropriate parameter search range, rendering optimization inefficient. Therefore, this paper proposes a disturbance-suppression-based objective function to design controllers that avoid oscillations. It also introduces a method for calculating the stability region of the cascade controller, revealing the impact of the inner loop controller on the stability region of outer loop controller, providing a suitable search range for optimization algorithms. Experiments demonstrate that the proposed tuning method based on performance optimization within the stability region not only prevents oscillations and improves temperature control precision but also establishes a search range for optimization algorithms, avoiding instability and improving solution speed and accuracy. This method is important for the development of precision temperature control systems and optimization-based tuning methods.