An Investigation in Performance of a Variable-Speed-Displacement Pump-Controlled Motor System

This paper is focused on investigating in the performance of a variable-speed-displacement pump-controlled motor system (VSDPM). As one key performance parameter, VSDPM's rated operating space is investigated through system model and numerical calculation. For comparison and analysis, two other typical systems' rated operating spaces are also calculated. As another key performance parameter, VSDPM's efficiency is studied through experiments. Given that VSDPM's efficiency changes with its displacement, the efficient displacement is first searched. With the efficient displacement, we then measure VSDPM's efficiency over its calculated operating space. Besides, the efficiency of a variable-displacement pump-controlledmotor system (VDPM) is also measured as a contrast. Through comparative analysis, we find that VSDPM can achieve a better efficiency performance at low speed and low torque. Compared to VDPM, its efficiency increment can be up to 11.5%. But VDPM performs better at high speed. Compared to VSDPM, its efficiency increment can be up to 4.8%. Finally, VSDPM's stand-by energy consumption is measured. While at stand-by mode, VSDPM consumes little power which is only 3% of VDPM's consumption.