Characteristic analysis of pump controlled motor speed servo in the hydraulic hoister

Abstract

To imitate the real hydraulic hoist used in mines and enhance its control performance, a pump controlled motor speed servo (PCMSS) is presented. Mathematic models of PCMSS with and without a position loop are established and their dynamic characteristics are studied by simulation and experiments. Results indicate that PCMSS without a position loop is susceptible to interrupt and uncontrollable only depending on the external motor speed closed-loop, whereas PCMSS with a position loop can achieve high stability and speed precision relying on the internal position closed-loop in the pump and the external speed closed-loop. Therefore, to achieve higher performances for PCMSS, the displacement of a variable delivery pump should be independently adjusted while motor speed is fed back and controlled in closed-loop. Based on this theory, two electrohydraulic servo control schemes are proposed for automation reform of traditional hydraulic hoisters.