Patents by Inventor Katsumi Ishikawa

Katsumi Ishikawa 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: 7880174
    Abstract: An object of the present invention is to reduce the conducting loss of an existing conversion circuit while suppressing its noise. The present invention is typically a circuit arrangement includes at least one switching device and a free-wheel diode connected in parallel with the switching device. The free-wheel diode is formed by connecting a silicon PiN diode in parallel with a Schottky barrier diode that uses a semiconductor material having a wider band gap than silicon as a base material. The silicon PiN diode and Schottky barrier diode are separate chips.
    Type: Grant
    Filed: February 12, 2008
    Date of Patent: February 1, 2011
    Assignee: Hitachi, Ltd.
    Inventors: Haruka Shimizu, Katsumi Ishikawa, Masahiro Nagasu, Dai Tsugawa
  • Publication number: 20100327837
    Abstract: The following problem associated with a semiconductor device of silicon or the like having low band gap is solved by temperature estimation using voltage drop in such a semiconductor device having low accuracy and this complicates a circuit for temperature detection suitable for practical use or a configuration for implementing a detection system. A power converter provided with an inverter circuit includes a semiconductor device whose band gap is larger than that of silicon and which has a range in which the temperature coefficient of voltage drop during conduction is positive. The power converter further includes a measurement condition setting circuit. This circuit adjusts the timing of the following measurement values used for temperature estimation at a device temperature estimation circuit to each other so that a measurement value of a voltage measurement circuit and a measurement value of a current measurement circuit become data obtained by measurement at the same time.
    Type: Application
    Filed: June 18, 2010
    Publication date: December 30, 2010
    Inventors: Dai TSUGAWA, Katsumi Ishikawa
  • Patent number: 7847555
    Abstract: A magnet which includes ferromagnetic powder to be mainly a mother phase containing iron or cobalt. The ferromagnetic powder is provided with a high-resistance layer which has a resistance higher than or equal to ten times as high as a resistance of the mother phase and a Vickers hardness lower than a Vickers hardness of the mother phase. The high-resistance layer is being formed partially or entirely on the surface of the ferromagnetic powder.
    Type: Grant
    Filed: March 18, 2008
    Date of Patent: December 7, 2010
    Assignee: Hitachi, Ltd.
    Inventors: Matahiro Komuro, Yuichi Satsu, Takao Imagawa, Katsumi Ishikawa, Takeyuki Itabashi
  • Patent number: 7830109
    Abstract: A movable member is moved in a preset direction in a linear motor. A characteristic-change position-detecting unit detects a position where the magnetic characteristic of the magnets has abruptly changed. The position detected is used as an origin-setting reference position. A reference position for the absolute position of the magnetic linear encoder is set based on the reference position.
    Type: Grant
    Filed: March 27, 2008
    Date of Patent: November 9, 2010
    Assignee: Wako Giken Co., Ltd
    Inventors: Toshihiko Sasaki, Kazuo Watanabe, Katsumi Ishikawa
  • Publication number: 20100265746
    Abstract: The invention provides a switching circuit of a power semiconductor device having connected in parallel SiC diodes with a small recovery current, capable of significantly reducing turn-on loss and recovery loss without increasing the noise in the MHz band, and contributing to reducing the loss and noise of inverters. The present invention provides a switching circuit and an inverter circuit of a power semiconductor device comprising a module combining Si-IGBT and SiC diodes, wherein an on-gate resistance is set smaller than an off-gate resistance.
    Type: Application
    Filed: April 15, 2010
    Publication date: October 21, 2010
    Inventors: Katsumi ISHIKAWA, Kazutoshi OGAWA, Masahiro NAGASU
  • Patent number: 7806991
    Abstract: A lamellar high resistance layer having resistivity ten times or higher than that of a mother phase containing iron or cobalt is formed and an oxygen content is controlled to 10 to 10000 ppm so that the reliability and residual magnetic flux density are increased.
    Type: Grant
    Filed: December 20, 2006
    Date of Patent: October 5, 2010
    Assignee: Hitachi, Ltd.
    Inventors: Matahiro Komuro, Yuichi Satsu, Takao Imagawa, Katsumi Ishikawa, Takeyuki Itabashi, Yuzo Kozono
  • Publication number: 20100244092
    Abstract: A power semiconductor apparatus which is provided with a first power semiconductor device using Si as a base substance and a second power semiconductor device using a semiconductor having an energy bandgap wider than the energy bandgap of Si as a base substance, and includes a first insulated metal substrate on which the first power semiconductor device is mounted, a first heat dissipation metal base on which the first insulated metal substrate is mounted, a second insulated metal substrate on which the second power semiconductor device is mounted, and a second heat dissipation metal base on which the second insulated metal substrate is mounted.
    Type: Application
    Filed: February 18, 2010
    Publication date: September 30, 2010
    Inventors: Katsumi ISHIKAWA, Kazutoshi Ogawa
  • Patent number: 7786631
    Abstract: A position-data converter and a motor-drive control device are connected. The position-data converter receives two-phase, sine-wave analog signals da and db from two first magnetic detectors, respectively, and converts these signals da and db to position data. On receiving a positioning instruction, the motor-drive control device calculates the value of current, from the current position signal generated by the position-data converter. The permanent magnets incorporated in a linear motor are used as components of a linear scale, as well.
    Type: Grant
    Filed: March 27, 2008
    Date of Patent: August 31, 2010
    Assignee: Wako Giken Co., Ltd
    Inventors: Toshihiko Sasaki, Kazuo Watanabe, Katsumi Ishikawa
  • Patent number: 7783396
    Abstract: In a conventional hybrid scheme used to mount a rechargeable battery in a motor vehicle, store into the battery the electric power that has been obtained via a regenerative brake, and utilize the power during acceleration of the vehicle, when a temperature rise of the battery due to charging or discharging causes a temperature of the battery to stay outside a defined range, it has been absolutely necessary to stop the battery charge or discharge, and fuel efficiency has decreased. This invention predicts a charge level and temperature of a rechargeable battery from the cruising input/output power requirements calculated from route information and historical records of cruising, prevents a stoppage of the battery by calculating chronological engine output and brake control data for the temperature to stay within a defined range, and hence improves fuel efficiency.
    Type: Grant
    Filed: January 16, 2008
    Date of Patent: August 24, 2010
    Assignee: Hitachi, Ltd.
    Inventors: Hiroshi Arita, Katsumi Ishikawa, Sunao Funakoshi, Masahiro Nagasu
  • Publication number: 20100207450
    Abstract: The invention provides a switching circuit and a power converter having a built-in power source for a conduction control terminal even if they have a single-arm structure. In the switching circuit having a switching device and a conduction control terminal power source capacitor, a negative terminal of the capacitor is connected to a reference voltage terminal of a main power source and to the gate terminal selectively through a half-bridge circuit and a positive terminal of the capacitor is selectively connected to a positive terminal of the main power source and to a source terminal of the switching device through a half-bridge circuit. The capacitor is charged when the positive terminal is connected to the main power source and discharges when the negative terminal is connected to the gate terminal and the positive terminal is connected to the source terminal and applies voltage to the gate terminal of the switching device.
    Type: Application
    Filed: February 17, 2010
    Publication date: August 19, 2010
    Inventors: Kazutoshi OGAWA, Katsumi Ishikawa
  • Patent number: 7746614
    Abstract: A drive circuit that controls a switching device ON/OFF and a soft cutoff command circuit that gradually decreases the gate terminal voltage of the switching device when short circuit of the switching device is detected. Additionally, an ON-pulse retention command circuit retains the output of the drive circuit ON when the gate terminal voltage is judged to have exceeded a specified value by a gate voltage judgment comparator that detects the gate terminal voltage of the switching device.
    Type: Grant
    Filed: January 23, 2009
    Date of Patent: June 29, 2010
    Assignee: Hitachi, Ltd.
    Inventors: Katsumi Ishikawa, Masataka Sasaki, Koichi Suda
  • Patent number: 7737761
    Abstract: A subject of the present invention is to reduce noise caused by ringing or the like while reducing turn-on power loss of the element and reverse recovery loss of the diode in a switching circuit of a power semiconductor element to which a SiC diode having small recovery current is connected in parallel. A means for solving the problem is to detect gate voltage and/or collector voltage of the power semiconductor switching element and change gate drive voltage in several stages based on the detected value.
    Type: Grant
    Filed: January 24, 2008
    Date of Patent: June 15, 2010
    Assignee: Hitachi, Ltd.
    Inventors: Katsumi Ishikawa, Masahiro Nagasu, Dai Tsugawa
  • Patent number: 7696650
    Abstract: A level shifting circuit, satisfying a requirement of a high tolerated dV/dt level, and a highly reliable inverter circuit, wherein a set pulse signal and a reset pulse signal, both of which are level-shifted to a potential side taking as reference a reference potential of a gate control terminal of a switching terminal, are obtained differentially and integrated, and, in case these pulse signals equal or exceed stipulated integrated values, are transmitted as regular control signals controlling the on/off state.
    Type: Grant
    Filed: September 4, 2008
    Date of Patent: April 13, 2010
    Assignee: Hitachi, Ltd.
    Inventors: Katsumi Ishikawa, Hideki Miyazaki, Koichi Suda, Katsunori Suzuki
  • Patent number: 7675727
    Abstract: A collector voltage of a power management semiconductor device is detected by a first comparator, and when the detected collector voltage exceeds a first reference voltage, the first comparator outputs a first detection signal. Furthermore, a gate voltage of the power management semiconductor device is detected by a second comparator, and when the detected gate voltage exceeds a second reference voltage, the second comparator outputs a second detection signal. The second reference voltage is a minimum gate voltage for feeding a rated power to the power management semiconductor device or over, and less than a line power voltage of a drive circuit of the power management semiconductor device. When both the first detection signal and second detection signal are being outputted, the gate voltage is reduced by a gate voltage reduction means so as to protect the power management semiconductor device from overcurrent and overvoltage.
    Type: Grant
    Filed: November 9, 2007
    Date of Patent: March 9, 2010
    Assignee: Hitachi, Ltd.
    Inventors: Masataka Sasaki, Katsumi Ishikawa, Ryuichi Saito, Koichi Suda, Katsuaki Takahashi
  • Patent number: 7671465
    Abstract: A power semiconductor module having an increased reliability against thermal fatigue includes a power semiconductor element, a lower-side electrode connected to the lower side of the element, a first insulating substrate connected to the upper side of the lower-side electrode and having metallic foils bonded on both surfaces thereof, an upper-side electrode connected to the upper side of the power semiconductor element, a second insulating substrate connected to the upper side of the upper-side electrode and having metallic foils bonded on both surfaces thereof, a first heat spreader connected to the lower side of the first insulating substrate, and a second heat spreader connected to the upper side of the second insulating substrate. The power semiconductor element and the first and second insulating substrates are sealed with a resin.
    Type: Grant
    Filed: January 25, 2007
    Date of Patent: March 2, 2010
    Assignee: Hitachi, Ltd.
    Inventors: Sunao Funakoshi, Katsumi Ishikawa, Tasao Soga
  • Publication number: 20090321924
    Abstract: A power semiconductor module includes: a power semiconductor device; a first heat dissipation plate; a second heat dissipation plate; a first channel; a second channel; a first channel wall; a second channel wall; a first refrigerant outlet provided on the first channel wall in a position corresponding to the power semiconductor device; a second refrigerant outlet provided on the second channel wall in a position corresponding to the power semiconductor device; first pin fins provided on at least one of the first heat dissipation plate and the second heat dissipation plate so as to be arranged radially around at least one of the first refrigerant outlet and the second refrigerant outlet; and second pin fins arranged in a staggered manner or in a tessellated manner around the first pin fins that are arranged radially.
    Type: Application
    Filed: June 29, 2009
    Publication date: December 31, 2009
    Applicant: Hitachi, Ltd.
    Inventors: Sunao Funakoshi, Katsumi Ishikawa
  • Patent number: 7631892
    Abstract: An airbag is disclosed wherein a lower deployment portion, right deployment portion, and left deployment portion are folded on the occupant side of a central deployment portion in an optional order. The upper deployment portion is folded to be located on the most occupant side and upper side of the folded deployment portions.
    Type: Grant
    Filed: February 25, 2005
    Date of Patent: December 15, 2009
    Assignee: Nihon Plast Co., Ltd.
    Inventors: Katsumi Ishikawa, Norimasa Goto
  • Patent number: 7570085
    Abstract: A gate driver circuit of a voltage drive type power semiconductor switching device capable of speeding up di/dt and dv/dt even during large-current driving to thereby reduce the switching loss is disclosed. This power semiconductor switching device gate driving circuit includes a drive circuit which applies a drive signal to the gate electrode of the power semiconductor switching device and a measurement unit for measuring a flow current of the power semiconductor switching device. Based on a detected value of the flow current of the power semiconductor switching device, the gate is made variable in mirror voltage thereof.
    Type: Grant
    Filed: January 19, 2007
    Date of Patent: August 4, 2009
    Assignee: Hitachi, Ltd.
    Inventors: Katsumi Ishikawa, Yutaka Sato, Masahiro Nagasu, Seiji Ishida
  • Patent number: 7564294
    Abstract: To provide a highly reliable inverter apparatus which discriminates long-cycle noise generated by the isolated signal transmission element from short-cycle dv/dt noise and induction noise. A low pass filter, band pass filter, and a switching means are provided between the input section of the gate drive circuit of the voltage-drive type power semiconductor switching element and the isolated signal transmission means that transmits the output of the control circuit; and an abnormal signal discriminating circuit is also provided which turns on and off the switching means according to the output of the band pass filter thereby eliminating long-cycle noise derived from the isolated signal transmission element, short-cycle dv/dt noise, and induction noise; and also outputs alarm signals.
    Type: Grant
    Filed: December 21, 2007
    Date of Patent: July 21, 2009
    Assignee: Hitachi, Ltd.
    Inventors: Katsumi Ishikawa, Hideki Miyazaki, Koichi Suda
  • Publication number: 20090168471
    Abstract: A circuit device includes at least one switching element and a free wheeling diode connected in parallel to the switching element. The free wheeling diode is made up of a Schottky barrier diode using a semiconductor material having a band gap larger than silicon as its base material and also a silicon PiN diode, which are connected in parallel. The Schottky barrier diode and the silicon PiN diode are provided in the form of separate chips. A circuit system is also provided wherein a diode having a Schottky junction of a compound semiconductor as a rectification element built therein is combined, and a relationship, R2>4L/C, with impedance R (resistance), L (inductance), and C (capacitance) determined by a closed circuit between a power source and a positive or negative terminal when the current of the diode becomes zero during recovery operation, is satisfied.
    Type: Application
    Filed: December 23, 2008
    Publication date: July 2, 2009
    Inventors: Dai Tsugawa, Katsumi Ishikawa, Masahiro Nagasu, Haruka Shimizu