Hydraulic multi-poin synchronized lifting system based on PWM

ZHOU Chong-wei， YANG Zi-jian， TANG Guan-rong
（Ningbo Saivs Machinery Co.， Ltd.， Ningbo 315135， China）

Abstract： Aiming at solving the problem of low positioning precision，low reliability，quality and safety on bridge construction，reconstruction and maintenance，a hydraulic multi-point synchronized lifting system based on programmable logic controller（PLC）and pulse width modulation（PWM）was designed. In the system，the on/off frequency of the electromagnetic valve was controlled by the PLC-based pulse signal.The multi-point （hydraulic cylinder） synchronized movements of unbalanced load was realized. After analysis of principle，the method of software and hardware was given. Remote control of the pressure，displacement and breakdown was realized by the controlling of each point movement using KingView. The practice results indicate that the system runs steadily，meets the requirements of field work.
Key words： pulse width modulation（PWM）； hydraulic control； multi-point synchronized lifting system； PLC