Patents by Inventor Yasuhiko Kokami
Yasuhiko Kokami 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).
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Patent number: 11575319Abstract: A DC-DC converter includes a high-side switch coupled between a first power supply and an output terminal, a low-side switch coupled between a second power supply and the output terminal, an inductor coupled to the output terminal, and a reverse current monitoring circuit that determines that a reverse current from the inductor to the output terminal occurs when the output terminal becomes a high voltage during a state in which the high-side switch and the low-side switch are in a dead time.Type: GrantFiled: December 30, 2020Date of Patent: February 7, 2023Assignee: RENESAS ELECTRONICS CORPORATIONInventors: Masayuki Ida, Yasuhiko Kokami, Hideyuki Tajima, Hiroyuki Inoue, Noboru Inomata
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Publication number: 20210249958Abstract: A DC-DC converter includes a high-side switch coupled between a first power supply and an output terminal, a low-side switch coupled between a second power supply and the output terminal, an inductor coupled to the output terminal, and a reverse current monitoring circuit that determines that a reverse current from the inductor to the output terminal occurs when the output terminal becomes a high voltage during a state in which the high-side switch and the low-side switch are in a dead time.Type: ApplicationFiled: December 30, 2020Publication date: August 12, 2021Inventors: Masayuki IDA, Yasuhiko KOKAMI, Hideyuki TAJIMA, Hiroyuki INOUE, Noboru INOMATA
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Patent number: 10302681Abstract: According to one embodiment, a current detection circuit (12) includes: a detection resistor (Rs) provided between a solenoid valve (106) and a solenoid driver (11); an amplification unit (121) configured to amplify a detected voltage of the detection resistor (Rs); an AD converter (122) that is driven by a reference voltage (Vref) generated based on a reference current (Iref) and configured to convert an output voltage from the amplification unit (121) into a digital value and output the digital value as a detected current value (D1); and a correction unit configured to perform a correction on the detected current value (D1).Type: GrantFiled: January 9, 2017Date of Patent: May 28, 2019Assignee: RENESAS ELECTRONICS CORPORATIONInventors: Masanori Otsuka, Wataru Saito, Yoshitaka Jingu, Yasuhiko Kokami, Satoshi Kondo, Junya Horishima
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Publication number: 20170212154Abstract: According to one embodiment, a current detection circuit (12) includes: a detection resistor (Rs) provided between a solenoid valve (106) and a solenoid driver (11); an amplification unit (121) configured to amplify a detected voltage of the detection resistor (Rs); an AD converter (122) that is driven by a reference voltage (Vref) generated based on a reference current (Iref) and configured to convert an output voltage from the amplification unit (121) into a digital value and output the digital value as a detected current value (D1); and a correction unit configured to perform a correction on the detected current value (D1).Type: ApplicationFiled: January 9, 2017Publication date: July 27, 2017Applicant: Renesas Electronics CorporationInventors: Masanori OTSUKA, Wataru SAITO, Yoshitaka JINGU, Yasuhiko KOKAMI, Satoshi KONDO, Junya HORISHIMA
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Patent number: 8569983Abstract: This invention provides a motor driving apparatus that made it possible to reduce torque ripples including those attributed to load variation of the motor and an associated method for control of motor revolution. An output stage to a multiphase DC motor is comprised of power elements to supply output voltages to multiphase coils and a predriver to supply drive voltages to the power elements. A resistor means detects a current flowing through the power elements. A supply current detector detects a voltage signal produced across the resistor means as a supply current, using a high-speed ADC and a moving average filter. An output controller generates a PWM signal with a frequency lower than the frequency of the high-speed ADC so that the current detected by the supply current detector conforms to a current signal indicating a motor revolving speed and transfers the PWM signal to the output stage.Type: GrantFiled: March 9, 2011Date of Patent: October 29, 2013Assignee: Renesas Electronics CorporationInventors: Minoru Kurosawa, Yasuhiko Kokami
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Patent number: 8362727Abstract: A control technology for a synchronous motor for suppressing rotational pulsation caused by variation in individuals without making a control algorithm complex is provided. In a motor drive system which is a control device for a synchronous motor, in order to suppress the pulsation component of N times as high as the AC frequency for driving the synchronous motor, a controller in which the phase property of the disturbance response of the controller with respect to the pulsation frequency is within ±45° is arranged. Therefore, the torque pulsation component generated from distortion in induction voltage or variation between phases is suppressed.Type: GrantFiled: December 8, 2010Date of Patent: January 29, 2013Assignee: Renesas Electronics CorporationInventors: Yoshitaka Iwaji, Yasuhiko Kokami, Minoru Kurosawa, Junnosuke Nakatsugawa
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Patent number: 8258732Abstract: A drive system of a permanent magnet motor is constituted of a mode switching trigger generator which monitors a state of a permanent magnet motor and issues a mode switching trigger, a conduction mode determining unit which receives the mode switching trigger and switches the mode of the permanent magnet motor, and a PWM generator which outputs a PWM signal to an inverter in accordance with the output of the conduction mode determining unit. The mode switching trigger is generated on condition that the speed electromotive force of the permanent magnet motor exceeds a constant or variable threshold value.Type: GrantFiled: February 6, 2009Date of Patent: September 4, 2012Assignee: Renesas Electronics CorporationInventors: Yoshitaka Iwaji, Yasuhiko Kokami, Minoru Kurosawa
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Patent number: 8232751Abstract: A position sensorless drive method capable of driving a permanent magnet motor by an ideal sine-wave current and enabling the driving from an extremely low-speed range in the vicinity of zero-speed is provided. A neutral-point potential of the permanent magnet motor is detected in synchronization with a PWM waveform of an inverter. The position of a rotor of the permanent magnet motor is estimated from the variation of the neutral-point potential. Since the neutral-point potential is varied in accordance with the magnetic circuit characteristics of an individual permanent magnet motor, the position can be detected regardless of the presence of saliency of the permanent magnet motor.Type: GrantFiled: August 26, 2009Date of Patent: July 31, 2012Assignee: Renesas Electronics CorporationInventors: Yoshitaka Iwaji, Yasuhiko Kokami, Minoru Kurosawa
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Patent number: 8004349Abstract: High-accuracy overcurrent detection is performed, while a loss resulting from the current detection is significantly reduced. A switch section outputs the voltage between the both terminals of a current detection resistor using an AND signal between an output signal from a hysteresis comparator and an output signal from a pre-driver. The voltage is filtered by an electrostatic capacitor element and a resistor, and inputted to a comparator. The comparator makes a comparison between the signals inputted to the two input terminals thereof, and outputs the result of the comparison to a digital filter. When an overcurrent begins to flow in a power supply unit, the levels of the voltages inputted to the two input terminals of the comparator are inverted so that the comparator outputs an inversion signal to the digital filter. The digital filter outputs a detection signal to an overcurrent detection circuit when an arbitrary time has elapsed.Type: GrantFiled: November 19, 2010Date of Patent: August 23, 2011Assignee: Renesas Electronics CorporationInventors: Osamu Yamashita, Yasuhiko Kokami, Masahiro Ishihara, Toshiyuki Tsunoda
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Publication number: 20110156625Abstract: This invention provides a motor driving apparatus that made it possible to reduce torque ripples including those attributed to load variation of the motor and an associated method for control of motor revolution. An output stage to a multiphase DC motor is comprised of power elements to supply output voltages to multiphase coils and a predriver to supply drive voltages to the power elements. A resistor means detects a current flowing through the power elements. A supply current detector detects a voltage signal produced across the resistor means as a supply current, using a high-speed ADC and a moving average filter. An output controller generates a PWM signal with a frequency lower than the frequency of the high-speed ADC so that the current detected by the supply current detector conforms to a current signal indicating a motor revolving speed and transfers the PWM signal to the output stage.Type: ApplicationFiled: March 9, 2011Publication date: June 30, 2011Applicant: RENESAS ELECTRONICS CORPORATIONInventors: Minoru KUROSAWA, Yasuhiko KOKAMI
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Publication number: 20110074324Abstract: A control technology for a synchronous motor for suppressing rotational pulsation caused by variation in individuals without making a control algorithm complex is provided. In a motor drive system which is a control device for a synchronous motor, in order to suppress the pulsation component of N times as high as the AC frequency for driving the synchronous motor, a controller in which the phase property of the disturbance response of the controller with respect to the pulsation frequency is within ±45° is arranged. Therefore, the torque pulsation component generated from distortion in induction voltage or variation between phases is suppressed.Type: ApplicationFiled: December 8, 2010Publication date: March 31, 2011Applicant: Renesas Electronics CorporationInventors: Yoshitaka Iwaji, Yasuhiko Kokami, Minoru Kurosawa, Junnosuke Nakatsugawa
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Patent number: 7915844Abstract: This invention provides a motor driving apparatus that made it possible to reduce torque ripples including those attributed to load variation of the motor and an associated method for control of motor revolution. An output stage to a multiphase DC motor is comprised of power elements to supply output voltages to multiphase coils and a predriver to supply drive voltages to the power elements. A resistor means detects a current flowing through the power elements. A supply current detector detects a voltage signal produced across the resistor means as a supply current, using a high-speed ADC and a moving average filter. An output controller generates a PWM signal with a frequency lower than the frequency of the high-speed ADC so that the current detected by the supply current detector conforms to a current signal indicating a motor revolving speed and transfers the PWM signal to the output stage.Type: GrantFiled: June 12, 2008Date of Patent: March 29, 2011Assignee: Renesas Electronics CorporationInventors: Minoru Kurosawa, Yasuhiko Kokami
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Publication number: 20110063021Abstract: High-accuracy overcurrent detection is performed, while a loss resulting from the current detection is significantly reduced. A switch section outputs the voltage between the both terminals of a current detection resistor using an AND signal between an output signal from a hysteresis comparator and an output signal from a pre-driver. The voltage is filtered by an electrostatic capacitor element and a resistor, and inputted to a comparator. The comparator makes a comparison between the signals inputted to the two input terminals thereof, and outputs the result of the comparison to a digital filter. When an overcurrent begins to flow in a power supply unit, the levels of the voltages inputted to the two input terminals of the comparator are inverted so that the comparator outputs an inversion signal to the digital filter. The digital filter outputs a detection signal to an overcurrent detection circuit when an arbitrary time has elapsed.Type: ApplicationFiled: November 19, 2010Publication date: March 17, 2011Applicant: RENESAS ELECTRONICS CORPORATIONInventors: Osamu YAMASHITA, Yasuhiko KOKAMI, Masahiro ISHIHARA, Toshiyuki TSUNODA
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Patent number: 7859209Abstract: A control technology for a synchronous motor for suppressing rotational pulsation caused by variation in individuals without making a control algorithm complex is provided. In a motor drive system which is a control device for a synchronous motor, in order to suppress the pulsation component of N times as high as the AC frequency for driving the synchronous motor, a controller in which the phase property of the disturbance response of the controller with respect to the pulsation frequency is within ±45° is arranged. Therefore, the torque pulsation component generated from distortion in induction voltage or variation between phases is suppressed.Type: GrantFiled: August 23, 2007Date of Patent: December 28, 2010Assignee: Renesas Electronics CorporationInventors: Yoshitaka Iwaji, Yasuhiko Kokami, Minoru Kurosawa, Junnosuke Nakatsugawa
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Patent number: 7859324Abstract: High-accuracy overcurrent detection is performed, while a loss resulting from the current detection is significantly reduced. A switch section outputs the voltage between the both terminals of a current detection resistor using an AND signal between an output signal from a hysteresis comparator and an output signal from a pre-driver. The voltage is filtered by an electrostatic capacitor element and a resistor, and inputted to a comparator. The comparator makes a comparison between the signals inputted to the two input terminals thereof, and outputs the result of the comparison to a digital filter. When an overcurrent begins to flow in a power supply unit, the levels of the voltages inputted to the two input terminals of the comparator are inverted so that the comparator outputs an inversion signal to the digital filter. The digital filter outputs a detection signal to an overcurrent detection circuit when an arbitrary time has elapsed.Type: GrantFiled: December 23, 2008Date of Patent: December 28, 2010Assignee: Renesas Electronics CorporationInventors: Osamu Yamashita, Yasuhiko Kokami, Masahiro Ishihara, Toshiyuki Tsunoda
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Patent number: 7848044Abstract: The present invention provides a VCM driver realizing low power consumption and high accuracy and a PWM amplifier compensating a dead time distortion. A phase compensator, a ?? modulator receiving an output signal of the phase compensator and converting the output signal to a control code of predetermined bits, a PWM modulator receiving the control code to produce a PWM signal, and an output circuit receiving the PWM signal to drive a voice coil constitute a forward path. A sense amplifier sensing a current of the voice coil, an ADC receiving an output signal of the sense amplifier, a low-pass filter receiving an output signal of the ADC, and a decimation filter receiving an output signal of the low-pass filter constitute a feedback path. An output signal of the decimation filter is fed back to the input side of the phase compensator to form a major feedback loop having a first-order characteristic loop gain.Type: GrantFiled: March 22, 2010Date of Patent: December 7, 2010Assignee: Renesas Electronics CorporationInventors: Yasuhiko Kokami, Hiroshi Kuroiwa
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Patent number: 7847500Abstract: Control technique of a synchronous motor capable of suppressing rotation pulsation caused by individual difference without complicating control algorithm is provided. A pulsation generator superimposing a pulsation component anticipated in advance to a current command for the synchronous motor and a correction current generator superimposing a correction signal substantially having an average value of zero to the current command are provided in a synchronous motor control device. By this configuration, the correction signal suppressing a distortion component is superimposed to a value of the current command with a simplified control configuration. Torque pulsation is suppressed by determining the correction signal from difference between a detection current and a command current.Type: GrantFiled: December 12, 2007Date of Patent: December 7, 2010Assignee: Renesas Technology CorporationInventors: Yoshitaka Iwaji, Junnosuke Nakatsugawa, Yasuhiko Kokami, Minoru Kurosawa
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Publication number: 20100177444Abstract: The present invention provides a VCM driver realizing low power consumption and high accuracy and a PWM amplifier compensating a dead time distortion. A phase compensator, a ?? modulator receiving an output signal of the phase compensator and converting the output signal to a control code of predetermined bits, a PWM modulator receiving the control code to produce a PWM signal, and an output circuit receiving the PWM signal to drive a voice coil constitute a forward path. A sense amplifier sensing a current of the voice coil, an ADC receiving an output signal of the sense amplifier, a low-pass filter receiving an output signal of the ADC, and a decimation filter receiving an output signal of the low-pass filter constitute a feedback path. An output signal of the decimation filter is fed back to the input side of the phase compensator to form a major feedback loop having a first-order characteristic loop gain.Type: ApplicationFiled: March 22, 2010Publication date: July 15, 2010Applicant: RENESAS TECHNOLOGY CORP.Inventors: Yasuhiko Kokami, Hiroshi Kuroiwa
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Patent number: 7750586Abstract: A drive control device of motor capable of starting up even a motor of such a type that the polarity of induced voltage does not switch every 180° of electrical angle or the polarity, positive or negative, does not occur with accuracy without causing a reverse rotation is provided. In a start-up control of motor, the following operation is performed: a current is passed through any coils in two phases, and the polarity of voltage induced in the non-conducting phase is detected. A conducting phase at start-up is determined based on the detected polarity of induced voltage. The average value of induced voltages in non-conducting phase detected with respect to the coils in respective phases is determined. The average value and the detected induced voltages are compared with each other, and relative polarities are determined from the magnitude relation with the average value to determine a conducting phase at start-up.Type: GrantFiled: August 4, 2008Date of Patent: July 6, 2010Assignee: Renesas Technology Corp.Inventors: Minoru Kurosawa, Yasuhiko Kokami
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Patent number: 7723937Abstract: A motor drive control device and motor startup method prevent startup noise and reduce startup time. At startup, a current to which a rotor does not react is passed through two phase coils of a polyphase DC motor in succession, and a voltage polarity induced in a non-conducting phase is detected. A first operation decodes the detected signal, and determines phase coils of the motor through which a current should pass to rotate the rotor and the energization direction. A second operation forms a control signal for passing a current according to the determination to drive the motor, detects a voltage peak induced in the non-conducting phase during the drive, and performs switching control of a conducting phase. In normal operation, the position of the rotor is detected based on a back EMF in each phase, and rotation control is performed.Type: GrantFiled: October 12, 2007Date of Patent: May 25, 2010Assignee: Renesas Technology Corp.Inventors: Minoru Kurosawa, Yasuhiko Kokami