Kabushiki Kaisha Yaskawa Denki

Kazuhiko Hiramatsu

Hideaki Iura

Mitsujiro Sawamura

Hajime Takahashi

Tadashi Sadohara

A power conversion apparatus includes a power converter, a voltage detector, a current detector, a detection voltage adjustor, and a controller. The power converter is configured to convert power from a power source into alternating-current power and is configured to output the alternating-current power to a power system. The voltage detector is configured to detect a voltage of the power system. The current detector is configured to detect a direct-current component of a current between the power converter and the power system. The detection voltage adjustor is configured to add a bias corresponding to the direct-current component to the voltage detected by the voltage detector, so as to generate a voltage detection signal, and is configured to output the voltage detection signal. The controller is configured to control the power converter to output an alternating-current voltage corresponding to the voltage detection signal.

Power conversion apparatus

A voltage type inverter apparatus comprising a voltage correcting portion. The voltage correcting portion corrects a given voltage instruction based on a value generated by passing a direct current bus voltage detected value through a first degree delay filter. In decelerating a speed of the alternating current motor, the speed is decelerated in an overexcited state by multiplying the given voltage instruction by a set gain. Simultaneously, a time constant of the first degree delay filter is made larger than a time constant in a normal control state.

Method of decelerating alternating current motor and inverter apparatus

There is provided an inverter capable of reducing a speed in a short period of time without generating an overcurrent even in a case of an alternating current motor which is easy to be saturated magnetically. A frequency of driving a motor is calculated by using a detecting value constituted by passing a direct current bus line voltage through a first filter portion, a voltage command is corrected by using a detecting value passing through a second filter portion, by making a time constant of the second filter portion larger than a time constant of the first filter portion in reducing a speed, the motor is brought into an overexcited state and loss is brought about in the motor.

Inverter apparatus and method of reducing speed of alternating current motor

Charging time of a capacitor is shortened while avoiding erroneous firing due to distortion of a power supply voltage and sustaining an inrush current at a constant level. In the charge control method of a capacitor in a thyristor converter comprising a thyristor for rectifying an AC voltage, a CPU delivering an on/off control signal to a thyristor driver for driving the thyristor, a voltage detection sensor for measuring the AC voltage and the capacitor charging voltage, and the capacitor connected with a DC circuit, the AC voltage and the capacitor charging voltage are measured by means of the voltage detection sensor, differential voltage between the firing phase voltage of the thyristor and the capacitor charging voltage is determined, and the thyristor is fired only when the firing phase voltage of the thyristor becomes lower than a specified voltage determined from the differential voltage.

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Fukuoka, Japan

Kazuhiko Hiramatsu