Patents by Inventor Akifumi ARARAGI

Akifumi ARARAGI 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: 10742207
    Abstract: Provided is a switch drive circuit that drives a plurality of switches mutually connected in parallel including a charge unit allowing charge current to flow to the gate of the switch; an off switch connecting between the gate of the switch and the ground; a detection unit detecting whether charge state of the gate of the switch is in a predetermined state; and a changeover unit that changes a state of off switches when the charge units allow the charge current to flow to the gate. The changeover unit changes the state of the off switches to be ON when detection units do not detect the charge state of the gate being in the predetermined state, and to change the state of the off switches to be OFF when detection units detect the charge state of the gate being in the predetermined state.
    Type: Grant
    Filed: June 24, 2019
    Date of Patent: August 11, 2020
    Assignee: DENSO CORPORATION
    Inventor: Akifumi Araragi
  • Patent number: 10715129
    Abstract: A switching element driving device includes a main on switch that is connected to gates of a first and second IGBTs and that, when brought into a conductive state, turns on the first and second IGBTs, diodes each disposed between the main on switch and one of the gates of the first and second IGBTs, the diodes having a forward direction from the main on switch to the gates of the first and second IGBTs, an on sub-switch that is connected to the gate of the second IGBT and that, when brought into the conductive state, turns on the second IGBT, and a control circuit that controls the conductive state and a non-conductive state of the main on switch and the on sub-switch.
    Type: Grant
    Filed: June 24, 2019
    Date of Patent: July 14, 2020
    Assignee: DENSO CORPORATION
    Inventor: Akifumi Araragi
  • Publication number: 20200036297
    Abstract: In a power converter, a control circuit has a speed adjustment resistor that limits a control current to adjust a switching speed of each of first and second switching elements. The speed adjustment resistor has a resistance that varies depending on a voltage at the control electrode of each of the first and second switching elements. A feedback route connects between the control electrode of the first switching element and the control electrode of the second switching element. The feedback route has a resistance that is set to be lower than a value of the resistance of the speed adjustment resistor during a predetermined Miller period of each of the first and second switching elements.
    Type: Application
    Filed: July 30, 2019
    Publication date: January 30, 2020
    Applicant: DENSO CORPORATION
    Inventors: Yuu YAMAHIRA, Tetsuya MATSUOKA, Kazuma FUKUSHIMA, Akifumi ARARAGI, Noriyuki KAKIMOTO, Masakiyo SUMITOMO
  • Publication number: 20200021293
    Abstract: In a signal transmission device having a pulse generator, a RS F/F circuit and a detector, the generator generates a set pulse signal and/or a reset pulse signal when a state of a PWM signal is changed. After the generation of the set pulse signal, the generator continuously generates following pulse signals after elapse of a predetermined period of time counted from the generation of the set pulse signal. The generator adjusts, based on a selector signal, the predetermined period of time counted to a time when the following pulse signal is transmitted at a first time. The detector detects the state of the selector signal based on the predetermined period of time counted from a time when the RS F/F circuit receives the set pulse signal or the reset pulse signal to a time when receiving the following pulse signal at a first time.
    Type: Application
    Filed: July 2, 2019
    Publication date: January 16, 2020
    Applicant: DENSO CORPORATION
    Inventor: Akifumi ARARAGI
  • Patent number: 10530349
    Abstract: In a signal transmission device having a pulse generator, a RS F/F circuit and a detector, the generator generates a set pulse signal and/or a reset pulse signal when a state of a PWM signal is changed. After the generation of the set pulse signal, the generator continuously generates following pulse signals after elapse of a predetermined period of time counted from the generation of the set pulse signal. The generator adjusts, based on a selector signal, the predetermined period of time counted to a time when the following pulse signal is transmitted at a first time. The detector detects the state of the selector signal based on the predetermined period of time counted from a time when the RS F/F circuit receives the set pulse signal or the reset pulse signal to a time when receiving the following pulse signal at a first time.
    Type: Grant
    Filed: July 2, 2019
    Date of Patent: January 7, 2020
    Assignee: DENSO CORPORATION
    Inventor: Akifumi Araragi
  • Publication number: 20200007118
    Abstract: A switching element driving device includes a main on switch that is connected to gates of a first and second IGBTs and that, when brought into a conductive state, turns on the first and second IGBTs, diodes each disposed between the main on switch and one of the gates of the first and second IGBTs, the diodes having a forward direction from the main on switch to the gates of the first and second IGBTs, an on sub-switch that is connected to the gate of the second IGBT and that, when brought into the conductive state, turns on the second IGBT, and a control circuit that controls the conductive state and a non-conductive state of the main on switch and the on sub-switch.
    Type: Application
    Filed: June 24, 2019
    Publication date: January 2, 2020
    Applicant: DENSO CORPORATION
    Inventor: Akifumi ARARAGI
  • Publication number: 20200007122
    Abstract: Provided is a switch drive circuit that drives a plurality of switches mutually connected in parallel including a charge unit allowing charge current to flow to the gate of the switch; an off switch connecting between the gate of the switch and the ground; a detection unit detecting whether charge state of the gate of the switch is in a predetermined state; and a changeover unit that changes a state of off switches when the charge units allow the charge current to flow to the gate. The changeover unit changes the state of the off switches to be ON when detection units do not detect the charge state of the gate being in the predetermined state, and to change the state of the off switches to be OFF when detection units detect the charge state of the gate being in the predetermined state.
    Type: Application
    Filed: June 24, 2019
    Publication date: January 2, 2020
    Applicant: DENSO CORPORATION
    Inventor: Akifumi ARARAGI
  • Patent number: 10511302
    Abstract: In a drive circuit, a control switch is electrically connected between a negative voltage source and a reference voltage generator. A drive controller switches a discharge switch and a control switch from an off state to an on state to thereby supply a first negative output voltage to a main control terminal of a target switch. The drive controller switches the discharge switch and the control switch from the on state to the off state to thereby change the first negative output voltage to be supplied to the main control terminal of the target switch to a second negative voltage based on the reference voltage generated by the reference voltage generator. The second negative voltage is more positive than the first negative voltage.
    Type: Grant
    Filed: December 21, 2018
    Date of Patent: December 17, 2019
    Assignee: DENSO CORPORATION
    Inventor: Akifumi Araragi
  • Publication number: 20190310675
    Abstract: In a drive circuit, a reference voltage generator generates a reference voltage that monotonically increases in a direction to pass through the threshold voltage during a voltage at the control terminal being lower than the Miller voltage. A buffer unit supplies the reference voltage output from the reference voltage generator to the control terminal of the switch, and adjusts a first transfer rate of electrical charge to or from the control terminal of the switch during at least part of a Miller period to be higher than a second transfer rate of electrical charge to or from the control terminal of the switch during the voltage at the control terminal of the switch passing through the threshold voltage. The Miller period is a period during which the voltage at the control terminal of the switch is maintained at the Miller voltage.
    Type: Application
    Filed: April 2, 2019
    Publication date: October 10, 2019
    Applicant: DENSO CORPORATION
    Inventor: Akifumi ARARAGI
  • Publication number: 20190310290
    Abstract: In an overcurrent detection circuit for switches parallely connected to each other, sense detectors are respectively provided for the switches. Each of the sense detectors detects a sense voltage of the corresponding one of the switches. The sense voltage of each of the switches is based on a sense current associated with a current flowing through the corresponding one of the switches. A parameter calculator calculates, based on the sense voltages calculated by the respective sense detectors, a determination parameter that is less subject to imbalance between currents flowing through the respective switches. A determiner determines whether a value of the determination parameter is higher than an overcurrent threshold, and determines that there is an overcurrent flowing through at least one of the switches upon determining that the value of the determination parameter is higher than the overcurrent threshold.
    Type: Application
    Filed: March 28, 2019
    Publication date: October 10, 2019
    Applicant: DENSO CORPORATION
    Inventor: Akifumi ARARAGI
  • Publication number: 20190199343
    Abstract: In a drive circuit, a control switch is electrically connected between a negative voltage source and a reference voltage generator. A drive controller switches a discharge switch and a control switch from an off state to an on state to thereby supply a first negative output voltage to a main control terminal of a target switch. The drive controller switches the discharge switch and the control switch from the on state to the off state to thereby change the first negative output voltage to be supplied to the main control terminal of the target switch to a second negative voltage based on the reference voltage generated by the reference voltage generator. The second negative voltage is more positive than the first negative voltage.
    Type: Application
    Filed: December 21, 2018
    Publication date: June 27, 2019
    Applicant: DENSO CORPORATION
    Inventor: Akifumi ARARAGI
  • Publication number: 20180309429
    Abstract: A drive circuit drives a switch that has first and second terminals and a control terminal. The drive circuit includes a discharge path, a capacitor, an AC suppressor and a DC voltage generator. The discharge path connects the control terminal and the second terminal. The capacitor has a high-potential terminal connected to the second terminal side and a low-potential terminal connected to the control terminal side. The AC suppressor has a first end connected to a part of the discharge path between the high-potential terminal the second terminal. The DC voltage generator has a connection terminal connected to a second end of the AC suppressor. The DC voltage generator regulates electric current flowing between the connection terminal and the AC suppressor so as to keep the potential of the part of the discharge path between the high-potential terminal and the second terminal higher than the potential of the low-potential terminal.
    Type: Application
    Filed: April 17, 2018
    Publication date: October 25, 2018
    Applicant: DENSO CORPORATION
    Inventor: Akifumi ARARAGI