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 controller 50 includes a virtual limitation torque calculation section 51 and electric motor rotational speed control sections 52 and 53. Variable horsepower control tables 52r and 53r are provided in the electric motor rotational speed control sections 52 and 53, and limit values q1*limit and q2*limit for a virtual displacement of the variable horsepower control tables 52r and 53r are changed such that a charge state of a power storage device 170 and a charge state of another power storage device 270 become equal to each other.

A storage battery (21) is configured of a plurality of cells (22A) to (22N) series-connected to each other. A battery controller (27) receives power supplied from a lead battery (31). The battery controller (27) executes balancing control that reduces variation in cell voltages (VcA) to (VcN) of the plurality of cells (22A) to (22N). The battery controller (27) executes the balancing control in a time range during which a voltage of the lead battery (31) becomes equal to or more than a predetermined given voltage value (V1) and a charging rate of the storage battery (21) becomes equal to or more than a predetermined given charging rate value (SOC1) after a key switch (16) is switched from an on state to an off state.

A mobile apparatus includes a main frame, an operating arm connected to the main frame, drive means configured to drive displacing means of the mobile apparatus, such as one or more wheels or tracks, drive means configured to drive the operating arm and a control system, connected to operating instruments for a driver, for controlling the drive means. The drive means for the displacing means includes an electric motor such that the drive of the displacing means is substantially electrical.

It becomes possible to prevent deterioration of an electric storage device due to overdischarge of the electric storage device and engine stalling due to insufficient assist or disabled assist when a charge amount of the electric storage device falls, ensure that work is continuously conducted, suppress an operator from feeling discomfort in operation, and ensure favorable operability. A pump target output power computing section (21) computes present pump demanded power on the basis of work related information, limits the present pump demanded power in response to a degree of reduction of a state of charge of an electric storage device (12a) when the state of charge is lower than a preset threshold, and computes the limited present pump demanded power as present pump target output power. A pump flow rate limiting command value computing section (22) computes a pump flow rate limiting command value on the basis of the present pump target output power in such a manner that output power of a hydraulic pump (9) does not exceed the pump target output power.

A mobile mining machine includes a plurality of traction elements, a plurality of motors, a power source in electrical communication with the plurality of motors, and an energy storage system in electrical communication with the plurality of motors and the power source. Each of the motors is coupled to an associated one of the plurality of traction elements. Each of the motors is driven by the associated traction element in a first mode, and drives the associated traction element in a second mode. The energy storage system includes a shaft, a rotor secured to the shaft, a stator extending around the rotor, and a flywheel coupled to the shaft for rotation therewith. In the first mode, rotation of the motors causes rotation of the flywheel to store kinetic energy. In the second mode, rotation of the rotor and the flywheel discharges kinetic energy to drive the motors.

A main controller 28 performs automatic stop control to stop an engine in a case where a preset automatic stop condition is satisfied, and includes a power source control processing section 283 controlling power supplied from a capacitor to an electric or electronic facility 70. The power source control processing section 283 estimates a charge amount by which the capacitor 40 is charged by the alternator 41 while an engine 9 is in operation, estimates an electric discharge amount corresponding to power supplied from the capacitor 40 to the electric or electronic facility 70 while the engine 9 is stopped under the automatic stop control, and stops supply of power from the capacitor 40 to the electric or electronic facility 70 when the electric discharge amount is determined to be larger than the charge amount while the engine 9 is stopped under the automatic stop control. This allows reliable suppression of degradation of the capacitor while the engine is under the automatic stop control.

A relay (25) connects and disconnects an electrical circuit to which an inverter (16) and an electricity storage device (19) are connected. A BCU (22) controls the electricity storage device (19). An HC (27) controls an electric motor (15), the inverter (16) and the BCU (22). The HC (27) and the BCU (22) respectively have FET switches (30, 31) for controlling supply and stop of the excitation current in the relay (25). When the electricity storage device (19) is determined to be in an abnormal state, the BCU (22) transmits an abnormal signal to the HC (27), and when a predetermined time has elapsed, turns off (opens) the first FET switch (30) of the BCU (22). The HC (27) executes stop processing based upon the abnormal signal received from the BCU (22) and then turns off (opens) the second FET switch (31) of the HC (27).

A power supply system can be used for an electric motor that drives a hydraulic pump in a demolition robot. The system provides a DC current from a source of power, controls and monitors the voltage level (VDCnom) of the DC current, can be activated, and supplies a pre-determined load current (I.sub.L) from the source of power to the electric motor. In order to offer improved operational availability and flexibility, the load current (I.sub.L) can be constituted by a DC current, and the electric motor can be a DC motor.

The present disclosure relates to a power distribution architecture for an off-road vehicle. The power distribution architecture includes a work circuit and a propel circuit and is configured for facilitating bi-directional power exchange between the work circuit and the propel circuit.

A hydraulic energy regeneration system for a work machine for boosting a pressure of a return hydraulic fluid of a hydraulic cylinder and regenerating the hydraulic fluid, prevents a bottom pressure from reaching an overload relief set pressure and suppresses a changeover shock to ensure favorable operability. The hydraulic energy regeneration system for the work machine, includes: a communication pressure boost passage that can boost a pressure of a discharge-side hydraulic fluid by communicating a discharge side and a suction side of the hydraulic cylinder with each other during an own weight fall of a driven body; a communication pressure boost valve that is disposed in the communication pressure boost passage and that can regulate one of or both of a pressure and a flow rate of the communication pressure boost passage; a reuse-side line and a reuse control valve or a regeneration-side line and a regeneration control valve that can regenerate a hydraulic fluid discharged from the hydraulic cylinder during the own weight fall of the driven body; and a controller. The controller is configured to reduce an opening degree of the communication pressure boost valve in response to an increase of the discharge-side pressure of the hydraulic cylinder right after the discharge-side pressure reaches a preset high load set pressure, and gradually reduces the opening degree of the communication pressure boost valve with passage of time.