Current Electric water heater There are three types of electric water heaters: quick heating type, instant heating type and water storage type. The quick heating type and water storage type electric water heaters still adjust the ratio of hot and cold water through the water mixing valve to adjust the bath temperature to suit their own. The instantaneous electric water heater does not mix cold water, and the principle of achieving constant temperature is: an infrared water flow sensor is set at the water inlet of the instantaneous electric water heater heating system to detect the water flow entering the heating system, which is converted into an electrical signal and input to the computer chip processor of the control system, and a temperature detection sensor is set at the water outlet, The detected temperature data results will also be input to the main board processor. After calculation by the processor, the heating system will be controlled according to the results, and the heating power will be adjusted to achieve a constant outlet water temperature.

At present, most of the temperature control technologies use feedback closed-loop control technology, which is relatively simple to establish mathematical model and requires less hardware resources. This kind of feedback control can meet the requirements in situations where the external environment is relatively constant and the real-time requirement is not high. However, for the variable use environment of water heater and the pure lag heating system and signal acquisition system, this kind of feedback closed-loop control cannot achieve good control effect.

At present, the domestic market can realize real constant temperature control Instant electric water heater There are few products, on the one hand, because the domestic technology is not yet mature; On the other hand, domestic Instant water heater The overall industrial chain product quality of the industry still needs to be improved. The accuracy and reliability of temperature and flow sensors, electronic components and PCB processing technology are all bottlenecks that restrict the realization of constant temperature control of domestic instantaneous electric water heaters.

There are also some integrations in China Intelligent thermostatic water heater The manufacturer introduced instant intelligent constant temperature hot water, which is mainly to set temperature sensors at the inlet and outlet of the water heater, calculate the output power through some classical algorithms such as PID or fuzzy algorithm, and realize stepless power regulation of the heating system by controlling silicon controlled by CPU. In fact, whether it is fuzzy control or PID control, its temperature control principle is a process in which the temperature gradually approaches the set value. It takes a long time to reach the set temperature, during which the temperature will fluctuate in a large range. Once the water pressure fluctuates, it will take a long time to reach the set water temperature, so it is impossible to achieve true constant temperature when using. Therefore, in addition to accurate temperature detection and power control, the detection and control of water flow is also crucial, so as to achieve true constant temperature.