Desigh Of High Resolution Electro-hydraulic Servo System Based On PMSM

Electro-hydraulic servo system, as a mechanical-electric-hydraulic hybridcontrol system, has the advantages of high efficiency, large output power, fastresponse, and high power density, and widely applies in modern civil and militaryfields. The research studies PMSM-based electro-hydraulic servo system, whichadjusts the speed of the servo motor to control the dosing pump speed, and thenrealizes speed control and pressure control function. It overwhelms the commonhigh-cost, inefficient pump control electro-hydraulic system and valve controlelectro-hydraulic system by low cost, high control precision, wide speed range,energy saving effect and high degree of automation. For two major problemsaffecting the electro-hydraulic servo system performance, load parameter variationand pressure pulsation, new solutions are put forward. Experiments are conducted toverify the effectiveness of the methods.This paper describes the overall scheme of the software and hardware system tobuild the electro-hydraulic servo system platform. It studies the flux oriented vectorcontrol algorithm for PMSM, and builds an SVPWM simulation model. Solidfoundation is laid for high performance electro-hydraulic servo system.Hydraulic system is a nonlinear system, with changing system parameter thataffects the performance of the pressure control performance. For this issue, theobject is studied, then a parameter identification method is proposed to identify themain parameter characterizing the system performance. With the identificationresult, a self-tuning PID controller is designed, thus the nonlinear load is equival entto linear load, improving system dynamic performance and steady-state performance.The method is effective and easy to implement, conducive to intelligent industrialautomation implementation.The electro-hydraulic system’s main parameters are measured, then controllersfor current loop, speed loop, pressure loop are respectively designed. Theelectro-hydraulic system is designed with appropriate bandwidth, high steady-stateaccuracy and good dynamic performance with good robustness against externaldisturbance, to achieve the purpose of flow control and pressure control and goodsteady and transient performance.In addition, when the electro-hydraulic servo system is running at pressurecontrol mode, pressure pulsation is difficult to avoid, impacting pressure holdingaccuracy and system stability. To solve this problem, this paper proposes a signalinjection method to proactively compensate for the inherent pressure pulsation, andreduce pressure ripples. Experiments proves that this method can effectively reducepressure pulsation and improve control accuracy.