Abstract: A hybrid work machine includes: an engine configured to drive a hydraulic pump as a hydraulic source of a hydraulic actuator; an engine-assist motor generator attached to the engine; an electric motor for use in a part of a driving system of the work machine; an electricity storage device configured to store generated power of the motor generator; a power converter disposed between the electric motor and DC buses; and a buck-boost converter disposed between the DC buses and the electricity storage device, and configured to perform power transfer between the DC buses and the electricity storage device by raising and lowering a voltage of the DC buses, the hybrid work machine, further comprises: a controller configured to temporarily raise the voltage of the DC buses when a torque required for the electric motor exceeds a torque outputtable at the voltage of the DC buses connected to the power converter.

Abstract: The controller estimates torque output by the motor and controls the current supplied to the motor in such a manner that a torque estimate of the motor obtained by the estimation corresponds to the torque command value. A torque estimation calculator 120 estimates the torque output by the motor. A phase error command calculator 125 calculates a command value of a phase error from the deviation between the torque estimate and a torque command value. A speed estimation calculator 130 outputs a speed estimate in such a manner that a phase error estimate corresponds to the command value of the phase error.

Abstract: A hybrid work machine includes: an engine configured to drive a hydraulic pump as a hydraulic source of a hydraulic actuator; an engine-assist motor generator attached to the engine; an electric motor for use in a part of a driving system of the work machine; an electricity storage device configured to store generated power of the motor generator; a power converter disposed between the electric motor and DC buses; and a buck-boost converter disposed between the DC buses and the electricity storage device, and configured to perform power transfer between the DC buses and the electricity storage device by raising and lowering a voltage of the DC buses, the hybrid work machine, further comprises: a controller configured to temporarily raise the voltage of the DC buses when a torque required for the electric motor exceeds a torque outputtable at the voltage of the DC buses connected to the power converter.

Abstract: The controller estimates torque output by the motor and controls the current supplied to the motor in such a manner that a torque estimate of the motor obtained by the estimation corresponds to the torque command value. A torque estimation calculator 120 estimates the torque output by the motor. A phase error command calculator 125 calculates a command value of a phase error from the deviation between the torque estimate and a torque command value. A speed estimation calculator 130 outputs a speed estimate in such a manner that a phase error estimate corresponds to the command value of the phase error.