Patents by Inventor Koetsu Fujita

Koetsu Fujita has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 6320775
    Abstract: A power conversion apparatus is provided which includes a power converter including a plurality of semiconductor switching elements which operate to perform power conversion, thereby to generate polyphase alternating current, an ac load circuit connected to an ac output side of the power converter, and a zero-phase power supply device connected to the ac load circuit. In this apparatus, the power converter, ac load circuit, and the zero-phase power supply device are connected in the form of a loop, so that voltage and current of the zero-phase power supply device provide zero-phase-sequence components when viewed from the ac output side of the power converter through the ac load circuit. The power converter performs time-sharing operations to supply and receive electric power to and from the ac load circuit, and supply and receive zero-phase-sequence power to and from the zero-phase power supply device.
    Type: Grant
    Filed: September 20, 2000
    Date of Patent: November 20, 2001
    Assignee: Fuji Electric Co., Ltd.
    Inventors: Junichi Ito, Koetsu Fujita
  • Patent number: 6137704
    Abstract: A power conversion apparatus is provided which includes a power converter including a plurality of semiconductor switching elements which operate to perform power conversion, thereby to generate polyphase alternating current, an ac load circuit connected to an ac output side of the power converter, and a zero-phase power supply device connected to the ac load circuit. In this apparatus, the power converter, ac load circuit, and the zero-phase power supply device are connected in the form of a loop, so that voltage and current of the zero-phase power supply device provide zero-phase-sequence components when viewed from the ac output side of the power converter through the ac load circuit. The power converter performs time-sharing operations to supply and receive electric power to and from the ac load circuit, and supply and receive zero-phase-sequence power to and from the zero-phase power supply device.
    Type: Grant
    Filed: June 3, 1998
    Date of Patent: October 24, 2000
    Assignee: Fuji Electric Co., Ltd.
    Inventors: Junichi Ito, Koetsu Fujita
  • Patent number: 6066928
    Abstract: An electric system for an electric vehicle includes a voltage type inverter that receives dc input voltage from a dc input circuit, and generates variable ac voltage of a variable frequency, and an ac motor including a plurality of windings each of which has one end connected to an ac output terminal of the voltage type inverter, the other ends of the windings being connected together to provide a neutral point of motor windings. A variable-voltage energy storage element is connected between the neutral point and a connecting point provided in the dc input circuit, and an on-vehicle dc power supply is connected to the opposite ends of the energy storage element or input terminals of the dc input circuit. The inverter performs switching operations in a zero-voltage vector mode, to operate as a chopper, so that power is transferred between the variable-voltage energy storage element, and the dc input side of the inverter.
    Type: Grant
    Filed: December 15, 1998
    Date of Patent: May 23, 2000
    Assignee: Fuji Electric Co., Ltd.
    Inventors: Shigenori Kinoshita, Koetsu Fujita, Junichi Ito
  • Patent number: 5991183
    Abstract: A polyphase voltage type converter is provided in which ac switches are provided between a power supply and a diode bridge, and reactors that are star-connected are connected to input terminals of the diode bridge. The ac switches are turned on and off so that non-continuous current flows through each of the reactors, whereby input current is formed into a sinusoidal waveform even with a dc voltage lower than that of a conventional converter.
    Type: Grant
    Filed: November 10, 1998
    Date of Patent: November 23, 1999
    Assignee: Fuji Electric Co., Ltd.
    Inventors: Junichi Itoh, Koetsu Fujita
  • Patent number: 5656911
    Abstract: A driving device controls a permanent-magnet synchronous motor having a permanent magnet in its rotor using a voltage-type inverter supplying drive power for the synchronous motor, makes the torque of the synchronous motor and the d-axis current flowing in the synchronous motor in the direction of the magnetic flux generated by the permanent magnet approach their own command values, and performs weakening field control by decreasing the d-axis current. To perform the above described control without complicated d-axis current command value operations or temperature amendments to motor constants, the driving device includes a proportional controller for outputting a d-axis signal proportional to the deviation between a d-axis current detection value and a d-axis current command value for the motor.
    Type: Grant
    Filed: December 20, 1995
    Date of Patent: August 12, 1997
    Assignees: Fuji Electric Company, Nissan Motor Company
    Inventors: Tomoharu Nakayama, Koetsu Fujita, Shigenori Kinoshita, Takao Yanase, Masahiko Hanazawa, Shinichiro Kitada, Toshio Kikuchi, Takeshi Aso
  • Patent number: 5466998
    Abstract: In an electric system for an electric vehicle, DC power of a main battery is converted into AC power by an inverter which has a power regenerative function. At startup, the system charges an input smoothing capacitor on the DC side of the inverter through an initial charging circuit with an initial charging switch and resistor. A main circuit switch that can stop current is connected between the main battery and the inverter. A rheostatic braking circuit with a rheostatic braking switch and a braking resistor is connected to the DC input side of the inverter for rheostatic breaking when required. Rheostatic braking takes over after regenerative braking when the main battery loses its power absorption capability, with the main circuit switch off. Semiconductors can be used as switches, and can be placed on a cooling body or modularized. Low-noise wires can be used to reduce noise.
    Type: Grant
    Filed: March 18, 1994
    Date of Patent: November 14, 1995
    Assignee: Fuji Electric Co., Ltd.
    Inventors: Shigenori Kinoshita, Takao Yanase, Koetsu Fujita
  • Patent number: 4849621
    Abstract: A non-contact, non-electromagnetic, compact, lightweight rotating body rotational-position detecting apparatus in which a disk or ring-shaped light source is spaced from a light receiving plate having thereon a region of photovoltaic material, by a shield plate which is coupled to the rotating body. The shield plate has a light-passing aperture therein so that the area of the photovoltaic material which is exposed to the light source varies with the angular position of the rotating body. The light source, photovoltaic regions, light shield and the shaft carrying the light shield and coupled to the rotating body are coaxial, the voltage produced across the load coupled to each of the photovoltaic regions being a function of the angle of rotation of the rotating body, thus indicating the angular position of the rotating body at any moment.
    Type: Grant
    Filed: March 14, 1988
    Date of Patent: July 18, 1989
    Assignee: Fuji Electric Co., Ltd.
    Inventors: Takao Yanase, Koetsu Fujita