Method of adjusting electronic expansion valve of air-conditioner
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Solution Overview
Problem
The existing PID control methods for electronic expansion valves in air conditioners are not responsive enough to varied air conditioner capacities and working conditions, leading to suboptimal energy efficiency ratios due to fixed proportional, integral, and derivative terms.
Innovation Solution
The method adjusts the integral coefficient of the PID algorithm based on outdoor ambient temperature and compressor running frequency, using different coefficients for high-temperature and low-temperature states, and varying frequencies to stabilize and improve the control of the electronic expansion valve opening, thereby optimizing energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed PID coefficients are used for electronic expansion valve control, then the control algorithm is simple, but the control accuracy deteriorates under varied air conditioner capacities and working conditions
Solution Approach 1:
The patent applies dynamics by making the integral coefficient variable rather than fixed. The coefficient dynamically adjusts based on outdoor ambient temperature and compressor running frequency, allowing the control algorithm to adapt to varied air conditioner capacities and working conditions while maintaining simplicity in the adjustment logic.
Solution Approach 2:
The patent changes the parameter of the integral coefficient based on operating conditions. By selecting different integral coefficient values according to outdoor temperature ranges and compressor frequency ranges, the system optimizes control accuracy for different working conditions without requiring a completely complex control algorithm.
2Speed
If a larger integral coefficient is used in PID algorithm, then the response speed improves, but the fluctuation of exhaust temperature and oscillation of valve opening amount increase
Solution Approach 1:
The patent uses dynamics by making the integral coefficient variable based on operating conditions. Under high-temperature states or low-frequency operation, a smaller integral coefficient is selected to reduce fluctuations and improve stability. Under non-high-temperature states or higher frequencies, a larger coefficient improves response speed, creating an optimal balance dynamically.
Solution Approach 2:
The patent changes the integral coefficient parameter according to outdoor temperature and compressor frequency. This parameter adaptation allows the system to achieve fast response when needed while maintaining temperature stability under conditions where large fluctuations would be harmful.
3Stability of the object's composition
If a smaller integral coefficient is used in PID algorithm, then the temperature stability improves, but the response speed deteriorates
Solution Approach 1:
The patent applies dynamics by selecting the integral coefficient based on real-time operating conditions. Rather than using a consistently small coefficient that would slow response, the system dynamically switches between smaller coefficients (for stability under high-temperature/low-frequency conditions) and larger coefficients (for faster response under other conditions).
Data Source
Figure 1
AI summary
Provided is a control method on electronic expansion valve in air conditioner, which comprises: obtaining a real-time running frequency of compressor, a real-time exhaust temperature and a real-time outdoor environment temperature as the compressor running; if the air conditioner working in cooling mode, using a first set rule or a second set rule to obtain an integral coefficient in which the selection is based on the comparison of the real-time outdoor environment temperature and a first set outdoor environment temperature; if the air conditioner working in heating mode, using a first set rule or a third set rule to obtain an integral coefficient in which the selection is based on the comparison of the real-time outdoor environment temperature and a second set outdoor environment temperature; performing a PID control on the electronic expansion valve by using an error of the difference between real-time exhaust temperature and a set target exhaust temperature. The method realizes an accurate and stable control on opening amount of electronic expansion valve in air conditioner.