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Motor control system for centrifuge

  • US 5,726,550 A
  • Filed: 07/30/1996
  • Issued: 03/10/1998
  • Est. Priority Date: 08/11/1995
  • Status: Expired due to Term
First Claim
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1. A power control apparatus for controlling power supplied to an electric motor employed in a centrifuge comprising:

  • a bi-directional supply power-converting circuit connected to an a.c. power supply, designed to convert a.c. current into d.c. current and vice versa and to reduce harmonic components contained in the current passing therethrough, said bi-directional supply power-converting circuit functioning as a step-up converter and a step-down converter, the step-up converter increasing a voltage level of the current flowing therethrough during conversion from the d.c. current into the a.c. current, the step-down converter decreasing a voltage level of the current flowing therethrough during conversion from the a.c. current into the d.c. current;

    a bi-directional motor power-convening circuit connected to said bi-directional supply power-converting circuit for providing power to the electric motor in a power running mode of motor operation and also providing power produced by the electric motor in a regenerating mode of motor operation to said bi-directional supply power-converting circuit;

    a d.c. power-converting circuit disposed between said bi-directional supply power-converting circuit and said bi-directional motor power-converting circuit, designed to work as a step-down converter which decreases a voltage level of an output from said bi-directional supply power-converting circuit to said bi-directional motor power-converting circuit and a step-up converter which increases a voltage level of an output from said bi-directional motor power-converting circuit to said bi-directional supply power-converting circuit;

    a motor energizing circuit disposed in parallel to said d.c. power-converting circuit to provide a given level of electric power to the electric motor to activate the electric motor in the regenerating mode; and

    a control circuit controlling operations of said bi-directional supply power-converting circuit, said bi-directional motor power-converting circuit, said d.c. power-converting circuit, and said motor energizing circuit to selectively activate the electric motor in the power running mode and the regenerating mode.

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