Quadratic Dynamic Matrix Control for Temperature Difference Regulation in Microwave Heating

Microwave heating has been widely applied in many fields due to its advantages of volumetric heating and rapid heating rates. In many industrial applications, temperature differences during the heating process must be strictly controlled by adjusting microwave power. However, classical control algorithms are difficult to apply effectively. In this paper, based on the quadratic dynamic matrix control (QDMC) algorithm, we propose a method for controlling temperature differences throughout the entire microwave heating process. First, we introduce a QDMC theoretical model, which consists of three steps: the predictive model, rolling optimization, and feedback correction. By integrating the measured temperature into the predictive model, the temperature differences can be constrained through quadratic optimization, thereby adjusting the microwave power. To validate the proposed theoretical model, we developed a practical microwave control system and recorded the temperature characteristics. The results demonstrate that when the maximum temperature difference between two points is set to 20 °C, the maximum temperature difference during the heating process can be controlled to less than 18 °C. This is significantly lower than the value achieved with the PID algorithm. These findings clearly indicate that the proposed temperature difference control algorithm can significantly improve heating uniformity.