Hydraulic drive system for electrically-driven hydraulic work machine

Abstract

A hydraulic drive system for an electrically-driven hydraulic work machine makes it possible to make a rated voltage of various electric equipment such as power storage devices common to one of an electrically-driven hydraulic work machine that is capable of being operated with lower horsepower and to prevent that only a power storage situation of one of the plurality of power storage devices significantly degrades together with operation of the electrically-driven hydraulic work machine and besides, to extend a time period within which each of actuators of the electrically-driven hydraulic work machine can obtain a predetermined speed. Accordingly, a controllerincludes a virtual limitation torque calculation sectionand electric motor rotational speed control sectionsand. Variable horsepower control tablesandare provided in the electric motor rotational speed control sectionsand, and limit values q*limit and q*limit for a virtual displacement of the variable horsepower control tablesandare changed such that a charge state of a power storage deviceand a charge state of another power storage devicebecome equal to each other.