Patents by Inventor Kimihiro Hoshi

Kimihiro Hoshi 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: 6271708
    Abstract: In a gate circuit having a turn-off gate circuit composed of: OFF gate power source Eoff of which one terminal is connected to the emitter of semiconductor switching element 81, and switch SWoff that connects the other terminal of OFF gate power source Eoff and the gate of semiconductor switching element S1 via resistor Rg, the gate circuit is provided with second switch SWoff2 that connects the other terminal of OFF gate power source Eoff and the gate of semiconductor switching element S1. By closing second switch SWoff2 at the timing at which the turn-off operation is completed, it will connect to OFF gate power source Eoff without passing through a resistor.
    Type: Grant
    Filed: August 5, 1999
    Date of Patent: August 7, 2001
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Kimihiro Hoshi, Takeo Kanai
  • Patent number: 6268990
    Abstract: A semiconductor protection device is used to suppress a surge voltage to a preset value or less, the surge voltage being caused at each turn-OFF time of 50 Hz to 20 kHz of a main IGBT functioning as a switch of a power converting system. The semiconductor protection device includes a protection IGBT for forming a bypass connected in parallel with the main IGBT and an electric field sensing element connected in a reverse direction between the collector of the main IGBT and the gate of the protection IGBT. When the surge voltage exceeds a preset value which is a breakdown voltage of the electric field sensing element, the protection IGBT is turned ON so as to cause a current generated by energy of the surge voltage to be bypassed.
    Type: Grant
    Filed: June 24, 1999
    Date of Patent: July 31, 2001
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Tsuneo Ogura, Kimihiro Hoshi
  • Patent number: 6111454
    Abstract: A semiconductor device comprises a voltage-driven switching element having a cathode and an anode, in which a voltage is to be applied between the cathode and anode, a power-supply circuit connected between the cathode and anode of the voltage-driven switching element and comprising capacitors, resistors and a reverse current-low preventing diode, for generating an intermediate voltage, a charging switching element for charging a gate of the voltage-driven switching element, using the intermediate voltage generated by the power-supply circuit, a discharging switching element for discharging the gate of the voltage-driven switching element, and a photovoltaic element for generating a photovoltaic power to control to drive the charging switching element and the discharging switching element.
    Type: Grant
    Filed: March 31, 1999
    Date of Patent: August 29, 2000
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Takashi Shinohe, Masakazu Yamaguchi, Kimihiro Hoshi
  • Patent number: 5910738
    Abstract: A semiconductor device includes a voltage-driven switching element having a cathode and an anode, in which a voltage is to be applied between the cathode and anode, a power-supply circuit connected between the cathode and anode of the voltage-driven switching element and comprising capacitors, resistors and a reverse current-low preventing diode, for generating an intermediate voltage, a charging switching element for charging a gate of the voltage-driven switching element, using the intermediate voltage generated by the power-supply circuit, a discharging switching element for discharging the gate of the voltage-driven switching element, and a photovoltaic element for generating a photovoltaic power to control to drive the charging switching element and the discharging switching element.
    Type: Grant
    Filed: April 5, 1996
    Date of Patent: June 8, 1999
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Takashi Shinohe, Masakazu Yamaguchi, Kimihiro Hoshi
  • Patent number: 5841647
    Abstract: A power conversion system including, a series circuit of an upper arm and a lower arm connected between a positive terminal and a negative terminal of a DC power source. Each of the upper and lower arms is composed of a power device having a large dv/dt withstand value and a first snubber circuit connected in parallel with the power device. Each of the first snubber circuits is composed of at least a first capacitor having a fixed capacitance. The power conversion system further includes two second snubber circuits, each composed of a series circuit of a second diode and a second capacitor, connected in parallel with one of the upper and lower arms, and a second resistor connected between a connecting point of the second diode and the second capacitor and one of the negative and positive terminals of the DC power source, respectively.
    Type: Grant
    Filed: October 3, 1997
    Date of Patent: November 24, 1998
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Kimihiro Hoshi