Hot Water Temperature Control Using Learned Feedforward Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing hot water supply apparatuses face challenges in achieving optimal responsiveness and stability in temperature control due to issues with integral control, such as phase delay-induced hunting and reduced responsiveness with low control gains, and limitations in the controllability of both feedback and feedforward control systems.
Innovation Solution
The implementation of a hot water supply apparatus that includes a heat exchanger, temperature detectors, a flow rate detector, and a control apparatus with a learning unit, feedforward control unit, feedback control unit, and addition unit, which learns a conversion factor between temperature and heat quantity, and uses this factor to calculate requested heat quantity generations for both feedforward and feedback control, thereby improving control accuracy and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If integral control gain is increased to improve responsiveness to set temperature changes, then control responsiveness is improved, but hunting occurs due to phase delay
Solution Approach 1:
The feedforward control unit calculates required heat quantity generation in advance based on the temperature difference between set temperature and inlet water temperature, and the flow rate. This preliminary action allows the system to proactively adjust the heater output before temperature deviations occur, improving responsiveness without causing hunting by avoiding reactive integral control adjustments.
2Stability of the object's composition
If integral control gain is decreased to prevent hunting, then temperature stability is improved, but control responsiveness to set temperature changes is lowered
Solution Approach 1:
The feedback control unit continuously monitors the actual tapping water temperature and compares it with the set temperature. Based on the temperature deviation, it calculates a correction value that is added to the feedforward control output. This feedback mechanism ensures temperature stability by correcting any deviations while maintaining responsiveness through the combined control strategy.
3Speed
If feedforward control is optimized for responsiveness, then control responsiveness is improved, but controllability of the overall control system is reduced
Solution Approach 1:
The control system dynamically adjusts the balance between feedforward and feedback control based on operating conditions. The feedforward control provides baseline responsiveness, while the feedback control dynamically corrects deviations. This dynamic combination allows the system to maintain both responsiveness and controllability across varying flow rates and temperature setpoints.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the responsiveness and stability of hot water temperature control by making the combination of feedforward and feedback control highly functional, allowing for improved accuracy and reduced reliance on integral control, which is difficult to adjust due to phase delays.
Implementation Method 1
a heat exchanger configured to heat passing water by means of a heat quantity generated by a heat source mechanism
Data Source
AI summary
A conversion factor learning unit successively updates a temperature conversion factor by learning a performance ratio of an output heat quantity with respect to an input scale number corresponding to a requested heat quantity generation to a hot water supply apparatus. The temperature conversion factor learned by the conversion factor learning unit is reflected in arithmetic operation of an FF scale number by a feedforward control unit and arithmetic operation of the FB scale number by the feedback control unit. An integral control in the feedback control unit is preferably turned off.