Claims
- 1. A centrifuge comprising:a basket arranged to receive materials; a motor interconnected to said basket; and, a motor controller coupled to said motor, said motor controller comprising: at least one power cell coupled to a main power supply and arranged to control a voltage applied to said motor, wherein said voltage adjusts the rotational speed of said motor, a first contactor coupling said at least one power cell to said motor, said first contactor switchable between a first state wherein an electrical connection is made between said at least one power cell and said motor, and a second state wherein an electrical connection is broken between said at least one power cell and said motor, and, a logic control module coupled to both said at least one power cell and said first contactor, said logic control module arranged to control said at least one power cell and said first contactor to selectively apply power to said motor during at least acceleration operations of said motor.
- 2. A centrifuge according to claim 1, wherein said voltage is a three phase voltage, and said motor controller further comprises three power cells, one power cell arranged to control an associated one phase of said three phase voltage.
- 3. A centrifuge according to claim 1, wherein said power cells comprise silicone controlled rectifiers.
- 4. A centrifuge according to claim 1, wherein said motor controller communicates with said at least one power cell to produce a voltage ramp-up to accelerate said basket.
- 5. A centrifuge according to claim 1, wherein said motor controller adjusts the speed of rotation of said basket by selectively turning on and off said at least one power cell.
- 6. A centrifuge according to claim 1, further comprising a speed determining device coupled to said logic control module.
- 7. A centrifuge according to claim 6, wherein said speed determining device comprises a tachometer.
- 8. A centrifuge according to claim 7, wherein said tachometer further comprises a magnetic pickup positioned to sense the speed and direction of a toothed gear mounted on a shaft of said motor.
- 9. A centrifuge according to claim 8, wherein said magnetic pickup is mounted on said motor.
- 10. A centrifuge according to claim 7, wherein said tachometer sends speed control data to a tachometer control unit, said tachometer control unit sending information to said logic control module.
- 11. A centrifuge according to claim 10, wherein said speed control data is transmitted as a pulsed speed signal.
- 12. A centrifuge according to claim 1, wherein said motor controller controls the speed of rotation of said basket by selectively turning on and off said at least one power cell.
- 13. A centrifuge according to claim 1, wherein said first contactor comprises a mechanical contactor.
- 14. A centrifuge according to claim 1, wherein said motor controller further comprises a second contactor coupling said at least one power cell to said motor, said second contactor switchable between a first state wherein an electrical connection is made between said at least one power cell and said motor, and a second state wherein an electrical connection is broken between said at least one power cell and said motor, said second contactor arranged such that, when said voltage is applied to said motor through said second contactor, the rotation of said motor is opposite the rotation of said motor when said voltage is applied to said motor through said first contactor.
- 15. A centrifuge according to claim 14, wherein said logic control module turns off said voltage at said at least one power cell prior to switching either said first or second contactors.
- 16. A centrifuge according to claim 1, further comprising a second contactor coupling said at least one power cell to said motor, said second contactor switchable between a first state wherein an electrical connection is made between said at least one power cell and said motor, and a second state wherein an electrical connection is broken between said at least one power cell and said motor wherein said motor comprises high speed windings and low speed windings, said first contactor connected to said low speed windings and said second contactor connected to said high speed windings.
- 17. A centrifuge according to claim 1, further comprising voltage suppression device.
- 18. A centrifuge according to claim 17, wherein said voltage suppression device comprises at least one varistor.
- 19. A centrifuge according to claim 17, wherein said voltage suppression device is arranged between said main power supply and said at least one power cells.
- 20. A centrifuge according to claim 1, wherein said motor controller integrates with a programmable logic control module programmed to control the cycling of said centrifuge.
- 21. A motor controller for a centrifuge machine comprising:a first power cell having an input coupled to a main power supply and an output, wherein said first power cell is switchable between an on state where power is supplied to said output, and an off state where no power is supplied to said output; a first contactor connected between the output of said first power cell and first windings of a motor, said first contactor switchable between a first state, wherein an electrical connection is made between said first power cell and said motor, and a second state wherein an electrical connection is broken between said first power cell and said motor; and, a logic control module coupled to both said first power cell and said first contactor, said logic control module arranged to interface with the controls of said centrifuge machine, said first contactor and said first power cell to selectively apply power to said motor at least during acceleration operations of said motor.
- 22. A motor controller for a centrifuge machine according to claim 21, further comprising second and third power cells, wherein said power supply comprises a three phase power supply and each of said first, second and third power cells couple a respective phase of said three phase power supply to said first contactor.
- 23. A motor controller for a centrifuge machine according to claim 21, wherein said first power cell comprises two silicone controlled rectifiers.
- 24. A motor controller for a centrifuge machine according to claim 23, wherein said logic control module controls the amount of power said first power cell supplies to said motor by varying the rate at which said logic control module switches said first power cell between said on and off states.
- 25. A motor controller for a centrifuge machine according to claim 21, further comprising:a second contactor connected between said first power cell and second windings of said motor, said second contactor switchable between a first state, wherein an electrical connection is made between said first power cell and said motor, and a second state wherein an electrical connection is broken between said first power cell and said motor, said second contactor further coupled to said logic control module, wherein said logic control module is further arranged to control said first and second contactors to selectively supply power to a select one of said first and second windings of said motor.
- 26. A motor controller for a centrifuge machine according to claim 25, wherein said first windings are low speed windings, said second windings are high speed windings.
- 27. A motor controller for a centrifuge machine according to claim 25, wherein said logic control module switches said first power cell to said off state prior to switching either said first or second contactors.
- 28. A motor controller for a centrifuge machine according to claim 21, further comprising:a second contactor connected between said first power cell and said first windings of said motor, said second contactor switchable between a first state, wherein an electrical connection is made between said first power cell and said motor, and a second state wherein an electrical connection is broken between said first power cell and said motor, said second contactor further coupled to said logic control module, wherein said second contactor is arranged to supply power to said motor such that said motor rotates in a direction opposite of the direction said motor rotates when powered through said first contactor.
- 29. A motor controller for a centrifuge machine according to claim 21, wherein said logic control module supplies power through said first power cell to said motor during acceleration operations of said motor, and said main power supply does not supply power to said motor through said first power cell during full speed operations of said motor.
- 30. A motor controller for a centrifuge machine according to claim 21, wherein said logic control module supplies power to said motor while said motor is rotating at a speed less than the maximum rated speed of said motor.
- 31. A motor controller for a centrifuge machine according to claim 21, further comprising a speed determinative device connected to a first input of said logic control module.
- 32. A motor controller for a centrifuge machine according to claim 31, wherein said speed determinative device comprises a tachometer.
- 33. A motor controller for a centrifuge machine according to claim 31, wherein said logic control module is programmable to maintain the rotation speed of said motor to within a speed band range during at least a portion of a load cycle.
- 34. A motor controller for a centrifuge machine according to claim 21, wherein said first contactor comprises a mechanical contactor.
- 35. A motor controller for a centrifuge machine according to claim 21, further comprising a voltage suppression device arranged to prevent voltage spikes from reaching said first power cell.
- 36. A motor controller for a centrifuge machine according to claim 35, wherein said voltage suppression device comprises a varistor.
- 37. A motor controller for a centrifuge machine according to claim 21, further comprising a current sensing device connected to said logic control module.
- 38. A motor controller for controlling a three phase, 2-speed AC motor, comprising:three power cells, each of said three power cells connected to a different one phase of a three phase power supply; a first contactor connected between each of said three power cells and first windings of said 2-speed AC motor, said first contactor switchable between a first state wherein an electrical connection is made between said at three power cells and said 2-speed AC motor, and a second state wherein an electrical connection is broken between said three power cells and said 2-speed AC motor, said first contactor arranged to bias said 2-speed AC motor to operate in a first direction; a second contactor connected between each of said three power cells and said first windings of said 2-speed AC motor, said second contactor switchable between a first state wherein an electrical connection is made between said at three power cells and said 2-speed AC motor, and a second state wherein an electrical connection is broken between said three power cells and said 2-speed AC motor, said second contactor arranged to bias said 2-speed AC motor to operate in a second direction; a third contactor connected between each of said three power cells and second windings of said 2-speed AC motor, said third contactor switchable between a first state wherein an electrical connection is made between said at three power cells and said 2-speed AC motor, and a second state wherein an electrical connection is broken between said three power cells and said 2-speed AC motor, said third contactor arranged to bias said 2-speed AC motor to operate in said first direction; a logic control module connected to said three power cells and said first, second and third contactors, said logic control module arranged to control said three power cells to control the amount of power said three power cells supply to said motor, said logic control module further arranged to control said contactors to selectively control the speed and direction of said motor; and, a speed determining device coupled to said logic control module, said speed determining device arranged to provide data concerning the rotational speed of said 2-speed AC motor to said logic control module.
- 39. A motor controller for controlling a three phase, 2-speed AC motor according to claim 38, further comprising a fourth contactor in series between said first and second contactors, and said motor, said fourth contactor coupled to said logic controller and arranged to tie said first windings of said motor together when said third contactor is in a first state and power is supplied to said second windings through said third contactor.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional Application No. 60/197,240 filed Apr. 14, 2000 that is incorporated herein by reference.
US Referenced Citations (25)
Foreign Referenced Citations (5)
Number |
Date |
Country |
SU 921008 |
Apr 1982 |
DE |
2133233 |
Jul 1984 |
DE |
1055971 |
Jan 1967 |
GB |
2133233 |
Jul 1984 |
GB |
WO 8700770 |
Feb 1987 |
WO |
Non-Patent Literature Citations (1)
Entry |
Baldor Motors and Drives; Multipurpose Soft Starter Sizes 8 to 840 AMP; Instillation & Operating Manual; 9/99. |
Provisional Applications (1)
|
Number |
Date |
Country |
|
60/197240 |
Apr 2000 |
US |