Abstract: In the water temperature constant temperature control of gas water heaters, there is output temperature fluctuation or overshoot, and the control is not ideal. This paper proposes a composite controller based on reality: expert PID controller. Through the theoretical analysis and mathematical modeling of the gas water heater, the first-order inertial system with hysteresis is obtained. Expert intelligent control is a kind of control algorithm combining practical control experience and theory. By extracting the characteristics of control objects, learning and reasoning, etc., a better control algorithm is obtained, which is combined with PID to obtain a composite control. The composite controller can eliminate or weaken the hysteresis to achieve a fast and stable temperature. The control algorithm and the control object model are simulated in Python, which saves the time for experimenting on the real machine and speeds up the tuning of the algorithm.

Key words: Expert algorithm, PID algorithm, Mathematical model, Python