A Comparison of an Ac-Servo Motor Driving Variable Rotational Speed and a Variable Displacement Pump-Controlled Systems for Velocity Control

Abstract

In the hydraulic servo control applications, hydraulic valve-controlled systems, which have a problem of low energy efficiency, are used mostly because of the high response characteristics. Hydraulic pump-controlled servo systems have high energy-efficiency. However, the conventional pump-controlled systems, which are altered by displacement via variable displacement pumps, have lower response. This paper aims to investigate the servo performance of the high response and high energy efficiency electro-hydraulic pump-controlled system driven by a variable rotational speed AC servo motor in comparison with the conventional pump-controlled systems which are altered by displacement via variable displacement pumps. For that, the control strategy, adaptive fuzzy sliding-mode controller (AFSMC) is introduced. The AFSMC can not only simplify the fuzzy rule base but also estimate the equivalent control force and online self-tune the rule base through the adaptive strategy. The developed high response variable rotational speed electro-hydraulic pump-controlled system controlled by AFSMC and the conventional variable displacement pump-controlled system (VDPCS) are implemented and verified experimentally for velocity control with various velocity targets and external loading conditions. Furthermore, the energy efficiencies of different experiments are analyzed and compared precisely by the power quality recorder used to measure the electrical power consumed by the AC servo motor.

Valve–pump parallel variable mode control for hydraulic speed regulation of high-power systems

“…[1][2][3] The PC system is more efficient as it avoids the throttling loss, but responds slowly, so it is suitable to some applications requiring high power with a slow response. 1,2,[4][5][6] The valve-pump combination control, which gives full play to advantages of valve control and PC, will make a hydraulic system efficient and offer a rapid response. 7 The combination of control modes has two types: series and parallel.…”