Hybrid Coding Control of Electro-hydraulic Pressure Servo System Using Array Digital Valves

doi:10.3901/JME.2024.04.143

Abstract

Abstract: Aiming at the technical requirements for highly reliable electro-hydraulic pressure servo control of variable-speed helicopter friction clutch transmission system, an array digital valves-controlled electro-hydraulic pressure servo structure is proposed based on A-type half-bridge hydraulic resistance and parallel digital hydraulic technology. Firstly, based on an in-depth analysis of the working principle of the system, its mathematical model is established, and the output flow characteristics of the equal coded array digital valves are revealed. Then, to improve the pressure control accuracy and the service life of the digital valves, a hybrid coding control strategy that integrates nonlinear PNM(pulse number modulation) coding, asymmetric differential PWM(pulse width modulation), signal buffer allocation, and signal cyclic allocation technology is proposed. Experimental results show that when the hybrid coding control strategy is adopted, the maximum and average errors are reduced by 47.6% and 87.9% respectively compared to the PNM coding controller, and the standard deviation of switching times is reduced from 31.6 to 2.5 compared to the differential PWM controller. Therefore, the proposed hybrid coding control strategy can obtain a better balance between the pressure control accuracy and the uniformity of the switching times among the digital valves.

Key words: array digital valves, pressure servo control, PNM coding, differential PWM, hybrid coding control

CLC Number:

TH137

GAO Qiang, LI Linfei, ZHU Yuchuan. Hybrid Coding Control of Electro-hydraulic Pressure Servo System Using Array Digital Valves[J]. Journal of Mechanical Engineering, 2024, 60(4): 143-154.

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