Hitachi Koki Co., Ltd.

Nobuharu Kido

Masahiro Inaniwa

Shinji Watanabe

Noriyasu Matsufuji

Yoshinori Tobita

Takahiro Fujimaki

Yoshitaka Niinai

Osamu Kawanobe

Satoshi Numata

Koji Unno

A centrifugal apparatus is disclosed which includes a rotor, a motor, a speed signal generator, including a disc having alternate reflective and non-reflective stripes, for generating a rotating speed signal of the rotor, a microprocessor (mpu), an analog processing circuit. The rotating speed of the rotor is judged by both the microprocessor and the analog processing circuit including a F/V converter and a voltage comparator independently, so that an overspeed condition is prevented. The mpu may further detect a motor rotating speed and compare the variation in the rotating speed signal of the rotor and the rotating speed of the motor. If the difference exceeds a reference, the mpu stops the rotor. Another disc of which reflective strip is replaced by a non reflective strip may be provided to the rotor and a pulse compensation circuit for compensating the lack of the pulse in the rotating speed signal is also provided. This type of the disc is provided to distinguish the types of these rotors. The pulse compensation circuit detects the lack of the pulse and then, generates and adds a pulse to the rotating speed signal.

Centrifugal apparatus with protection

A power control apparatus for controlling power supplied to an electric motor rotating a rotor employed in a centrifuge is provided. The power control apparatus includes first and second inverters and a smoothing capacitor disposed between the first and second inverters. In a motor power mode, the first inverter charges the smoothing capacitor with power supplied by an AC power supply, while the second inverter charges, in a motor braking mode, the smoothing capacitor with power regenerated by the motor during a braking operation for returning the regenerated power back to the AC power supply through the first inverter. An reactor is arranged between the AC power supply and the first inverter for reducing harmonic components contained in the current supplied from or back to the AC power supply.

Motor control system for centrifugal machine

A centrifugal apparatus includes a rotor having a marker for generating an index signal, a motor for rotating the rotor, first and second detectors for detecting the index signal with rotation of the rotor to generate first and second detection signals, an input terminal for receiving supply power, a drive circuit for generating a drive signal from the supply power according to the first detection signal, and first and second switch circuits for controlling the supply of the drive signal to the motor. First and second judging portions are used to detect whether the first and second detection signals are respectfully generated within a given condition. The first judging portion operates the first switch circuit to stop the drive signal from being supplied to the motor when the first detection signal is not generated within the given condition, while said second judging portion operates the second switch circuit to stop the drive signal from being supplied to the motor when the second detection signal is not generated within the given condition. The first and second detectors, judging portions, and switch circuits, respectively, independently operate to provide double feedback loops, so that an overspeed or the like is prevented.

Centrifugal apparatus with overspeed protection

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Hitachinaka, Japan

Nobuharu Kido