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Name of Experiment: application of power amplifier in dynamic characteristics test of direct drive water hydraulic valve of voice coil motor

Research Direction：dynamic characteristics of direct drive water hydraulic valves

Experiment Contents: the closed-loop controller of direct drive valve is designed by mathematical model and simulation software MATLAB-Simulink, and the dynamic characteristics and steady-state characteristics of the system are analyzed.

Experiment Objective：the closed-loop control system of direct drive valve based on LabVIEW was built by NI multifunctional IO equipment, and the dynamic characteristics and steady-state characteristics of direct drive valve were experimentally studied.

Experiment Equipment: signal generator, power amplifier, voice coil motor direct drive valve, force sensor, displacement sensor, position regulator

Experiment Process：

（1）Open-loop test of direct drive water hydraulic valve for voice coil motor

The open-loop test is mainly to set different step voltages of the voice coil motor, observe the steady-state value of spool displacement, and then compare it with the simulation steady-state value to verify the accuracy of the model or the gap between the theoretical model and the actual model.

（2）Design of PID closed-loop control system based on Simulink

The control system is composed of position loop and current loop, and the NI equipment based on LabVIEW is the core, which mainly completes the data acquisition and control algorithm of current and position closed-loop system. By making full use of the rich IO functions of LabVIEW, the signal can be detected stably, which is convenient for the realization of the control system.

（3）Experimental study on PID direct drive valve control based on LabVIEW

The closed-loop PID of the direct drive valve of voice coil motor is realized by writing LabVIEW control program on the desktop, and completing the realization of PID control algorithm, the output of control quantity and the acquisition of feedback signal of current sensor and displacement sensor with multi-function IO device NI-6341. Then NI-6341 gives the PID control to the linear power amplifier to complete the transformation of the control signal to the power drive signal, which is used to drive the voice coil motor.

Experiment Result：

（1）The steady-state numerical comparison between the test and simulation is shown in the figure. It can be seen from the figure that the simulation model can well describe the trend of spool displacement variation, and the maximum deviation is about 5% of the total stroke of the spool. The source of deviation caused by model prediction data and test data is: in practice, when the compression of the reset spring is between 1 mm and 3mm, its stiffness coefficient is 23N/mm, 26.3N/mm, 24.5N/mm, respectively, while the stiffness coefficient of the spring in the simulation is set as a constant 23N/mm.

（2）It can be seen from the comparison curve that the step curve in the test has a large lag in the adjustment time, and the displacement in the simulation is fast in the rising stage, and the displacement overshoot of the simulation response result is larger than that of the test result. By analyzing the reasons, the deviation should come from the damping effect caused by the leakage of the hydraulic valve and the damping effect caused by the dynamic flow change in the closed chamber, which is not considered in the simulation model. These two damping effects make the overall dynamic response of the direct drive valve not as good as in the simulation.

The performance of the amplifier in the experiment：amplify the voltage and drive the click direct drive valve