Crane, and crane control method
AssigneeMitsui Engineering & Shipbuilding Co., Ltd.
InventorsKatsunori Ishii, Koji Ohi, Hiroshi Kubo
Life of this patent
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Abstract
Provided is a crane which can suppress deformation and vibration of a crane structure in travel and stop of the crane. Inverters are installed respectively in travel devices which are arranged on the opposite sides with a gap in a transverse direction. Each of the inverters independently measures a torque generated in a motors to which the inverter is connected and reduces the rotation speed in the command from a controller to the motor such that the greater the measured torque is, the greater a ratio of reduction is.
Claims14
A crane including travel devices which are arranged on opposite sides with a gap in a transverse direction crossing a travel direction and a crane structure which is supported by the travel devices, the travel devices each including a travel wheel, a motor which transmits power to the travel wheel, an inverter which is connected to the motor and which controls a rotation speed of the motor, and a controller which gives a command of the rotation speed to the motor via the inverter, wherein
- each of the inverters includes a torque measurement unit which measures a torque generated in the motor to which the inverter is connected and a control unit which reduces the rotation speed in the command from the controller to the motor such that the greater a value of the torque obtained by the torque measurement unit is, the greater a ratio of reduction with respect to the rotation speed in the command is,
- a control of each of the control units is performed within a range in which a ratio of the torque measured by the torque measurement unit is greater than 0% and less than 150% with respect to a rated torque of the motor to which the inverter is connected, and
- the inverters independently perform measurement with the torque measurement units and the control with the control units.
A method of controlling a crane including travel devices which are arranged on opposite sides with a gap in a transverse direction crossing a travel direction and a crane structure which is supported by the travel devices, the travel devices each including a travel wheel, a motor which transmits power to the travel wheel, an inverter which is connected to the motor and which controls a rotation speed of the motor, and a controller which gives a command of the rotation speed to the motor via the inverter, comprising:
- causing each of the inverters to independently measure a torque generated in the motor to which the inverter is connected and reduce the rotation speed in the command from the controller to the motor such that the greater the measured torque is, the greater a ratio of reduction with respect to the rotation speed in the command is, so as to reduce misalignment in the travel direction between the travel devices arranged on the opposite sides,
- wherein the reduction of the rotation speed in the command is effected by the inverters within a range in which a ratio of the torque measured by the torque measurement unit is greater than 0% and less than 150% with respect to a rated torque of the motor to which the inverter is connected.
Dependencies are inferred from the claim text.