Screw decanter centrifuge having a speed-torque controller
First Claim
1. A screw decanter centrifuge, comprising:
- a cylindrical bowl rotatable in one direction;
a main drive motor coupled to said bowl for rotatably driving said bowl;
a screw conveyor disposed concentrically in said bowl and being rotatable in the same direction as said bowl at a differential rotation speed from said bowl, said differential rotation speed being changed in response to a carrying torque of said screw conveyor; and
an induction type screw conveyor motor for driving said screw conveyor, said induction type screws conveyor motor having a shaft connected directly to a shaft of said screw conveyor, and said induction type screw conveyor motor being controlled by a spaced-torque controller;
wherein said speed-torque controller includes;
a speed controller for calculating said differential rotation speed based on rotations indicated by an induction motor tachometer for detecting a speed of said induction type screw conveyor motor, and on rotations indicated by a bowl tachometer for detecting a speed of said bowl; and
a vector control inverter for independently controlling an exciting current and a torque current of said induction type screw conveyor motor based on a speed command value outputted from said speed controller and an actual speed of said induction type screw conveyor motor outputted from said induction motor tachometer.
1 Assignment
0 Petitions
Accused Products
Abstract
A screw decanter centrifuge including a cylindrical bowl rotatable in one direction, a main drive motor coupled to the bowl for rotatably driving the bowl, a screw conveyor which is disposed concentrically in the bowl and which is rotatable in the same direction as the bowl at a differential rotation speed from the bowl, and an induction type screw conveyor motor for driving the screw conveyor. The differential rotation speed is changed in response to a carrying torque of the screw conveyor. An induction type screw conveyor motor is provided for driving the screw conveyor. The induction type screw conveyor motor has a shaft connected directly to, or coupled to, a shaft of the screw conveyor, and the induction type screw conveyor motor is controlled by a speed-torque controller. The speed-torque controller includes a speed controller for calculating the differential rotation speed based on rotations indicated by an induction motor tachometer for detecting a speed of the induction type screw conveyor motor, and on rotations indicated by a bowl tachometer for detecting a speed of the bowl. The speed-torque controller further includes a vector control inverter for independently controlling an exciting current and a torque current of the induction type screw conveyor motor based on a speed command value outputted from the speed controller and an actual speed of the induction type screw conveyor motor outputted from the induction motor tachometer.
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Citations
4 Claims
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1. A screw decanter centrifuge, comprising:
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a cylindrical bowl rotatable in one direction; a main drive motor coupled to said bowl for rotatably driving said bowl; a screw conveyor disposed concentrically in said bowl and being rotatable in the same direction as said bowl at a differential rotation speed from said bowl, said differential rotation speed being changed in response to a carrying torque of said screw conveyor; and an induction type screw conveyor motor for driving said screw conveyor, said induction type screws conveyor motor having a shaft connected directly to a shaft of said screw conveyor, and said induction type screw conveyor motor being controlled by a spaced-torque controller; wherein said speed-torque controller includes; a speed controller for calculating said differential rotation speed based on rotations indicated by an induction motor tachometer for detecting a speed of said induction type screw conveyor motor, and on rotations indicated by a bowl tachometer for detecting a speed of said bowl; and a vector control inverter for independently controlling an exciting current and a torque current of said induction type screw conveyor motor based on a speed command value outputted from said speed controller and an actual speed of said induction type screw conveyor motor outputted from said induction motor tachometer. - View Dependent Claims (2)
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3. A screw decanter centrifuge, comprising:
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a cylindrical bowl rotatable in one direction; a main drive motor coupled to said bowl for rotatably driving said bowl; a screw conveyor disposed concentrically in said bowl and being rotatable in the same direction as said bowl at a differential rotation speed from said bowl, said differential rotation speed being changed in response to a carrying torque of said screw conveyor; and an induction type screw conveyor motor for driving said screw conveyor, said induction type screw conveyor motor having a shaft coupled to a shaft of said screw conveyor through a flexural coupling, and said induction type screw conveyor motor being controlled by a speed-torque controller; wherein said speed-torque controller includes; a speed controller for calculating said differential rotation speed based on rotations indicated by an induction motor tachometer for detecting a speed of said induction type screw conveyor motor, and on rotations indicated by a bowl tachometer for detecting a speed of said bowl; and a vector control inverter for independently controlling an exciting current and a torque current of said induction type screw conveyor motor based on a speed command value outputted from said speed controller and an actual speed of said induction type screw conveyor motor outputted from said induction motor tachometer. - View Dependent Claims (4)
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Specification