As a key control component in hydraulic servo system, servo valve is widely used in industrial automation, aerospace, precision machine tools and other fields. Its function is to convert electric signal into hydraulic output and realize accurate control of actuator. However, in the actual operation process, the servo valve often resonates due to improper system design or external disturbance. Resonance will not only affect the control accuracy of the system, but also cause the fatigue damage of the mechanical structure and even lead to the failure of the whole system. Therefore, how to effectively avoid the resonance problem of servo valve is one of the key technologies to ensure the stability and reliability of the system.
First, the cause analysis of servo valve resonance
The resonance of servo valve mainly comes from the coupling between dynamic response in hydraulic system and external excitation. Specific reasons include:
1. Improper matching between the valve and the actuator: When the dynamic response characteristics of the servo valve do not match the inertia of the hydraulic cylinder or motor, it is easy to form resonance at a specific frequency.
2. There are elastic elements in the system, such as the compressibility of pipelines and hydraulic oil, which will introduce additional elastic links, thus generating vibration under high-frequency excitation.
3. The parameter setting of feedback control system is unreasonable: the proportional gain of PID controller is too high and the integration time is too short, which may cause system oscillation.
4. External disturbance excitation: The natural frequency of the system may be excited by load change, mechanical shock or vibration of other power equipment.
Second, measures to prevent servo valve resonance
In order to avoid the resonance phenomenon of servo valve, we can start with system design, component selection, control strategy and so on:
1. Optimize the system structure design
The dynamic characteristics of the whole system should be considered in the system design stage. For example, shortening the length of hydraulic pipeline to reduce the elastic influence, choosing a more rigid installation structure, and rationally arranging the positions of actuator and servo valve to reduce the flexible links in mechanical transmission chain.
2. Select the appropriate servo valve and actuator.
According to the working frequency and response requirements, select the servo valve with appropriate bandwidth and ensure that it does not overlap with the natural frequency of the actuator. At the same time, the selection of actuators with high responsiveness and good damping characteristics is helpful to suppress the occurrence of resonance.
3. Set the controller parameters reasonably.
Advanced control algorithms, such as feedforward control, adaptive control and fuzzy control, can improve the robustness of the system. In addition, fine tuning of PID controller, appropriate reduction of proportional gain and introduction of differential link can effectively suppress the oscillation caused by high frequency response.
4. Add damping device
Adding hydraulic damper or mechanical damper to the system is a simple and effective method to suppress resonance. By absorbing the excess energy of the system, the oscillation amplitude of the system is reduced.
5. Analyze and simulate the system frequency.
Before the formal operation of the system, modal analysis and resonance frequency prediction are carried out by using simulation software (such as MATLAB/Simulink, AMESim, etc.), which is helpful to find the potential resonance risk in advance and take corresponding preventive measures.
III. Conclusion
To sum up, the root of servo valve resonance problem lies in the mismatch between system dynamic characteristics and external excitation. By optimizing the system structure, reasonable selection, scientific parameter adjustment and introducing damping measures, resonance can be avoided to a great extent. At the same time, with the help of modern simulation technology and advanced control strategy, the stability and reliability of the system can also be effectively improved. In engineering practice, the dynamic performance of servo valve and its system should be taken as the key consideration, so as to ensure the long-term stable operation of the equipment and improve the overall control accuracy and production efficiency.