Patents by Inventor Kenichi Akita
Kenichi Akita 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: 11598791Abstract: Magnetic sensors each disposed to face each of current paths for each of windings with 2n phases (n is a multiple of three) in an AC rotating machine are included, and when each of a DC component and an AC component in a d-axis sum current and a q-axis sum current obtained by performing a dq-transformation into a two-axis coordinate system on 2n detection currents on the assumption that all current amplitudes of the windings are the same is represented collectively with each of terms expressed by sine functions with different phases to one another, each of the current paths at each of 2n current path arrangement positions is arranged to have a positional relationship where error components are reduced by cancellation among coefficients included at least in one of the terms or by cancellation among values of the terms.Type: GrantFiled: April 22, 2020Date of Patent: March 7, 2023Assignee: Mitsubishi Electric CorporationInventors: Akira Furukawa, Kenichi Akita, Daisuke Sasaki
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Patent number: 11296535Abstract: The control device for an electric motor according to this application provides a battery voltage detecting part for detecting a battery voltage at the time of driving a motor driven by a battery, and a minimum voltage holding part for keeping the battery voltage above the predetermined voltage by reducing the consumption current of the electric motor when the battery voltage detected by the battery voltage detecting part falls below a predetermined voltage during driving of the electric motor, so that it is possible to suppress a reduction in battery voltage during driving at low cost, and it is possible to keep the battery voltage above the predetermined voltage.Type: GrantFiled: December 14, 2016Date of Patent: April 5, 2022Assignee: Mitsubishi Electric CorporationInventors: Nobuaki Yoshioka, Kenichi Akita, Mitsunori Tabata
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Patent number: 11181558Abstract: Magnetic sensors each disposed to face each of current paths for each of windings with 2n phases (n is a multiple of three) in an AC rotating machine are included, and when each of a DC component and an AC component in a d-axis sum current and a q-axis sum current obtained by performing a dq-transformation into a two-axis coordinate system on 2n detection currents on the assumption that all current amplitudes of the windings are the same is represented collectively with each of terms expressed by sine functions with different phases, each of the current paths at each of 2n current path arrangement positions is arranged to have a positional relationship where error components are reduced by cancellation among coefficients included at least in one of the term or by cancellation among values of the terms.Type: GrantFiled: April 22, 2020Date of Patent: November 23, 2021Assignee: Mitsubishi Electric CorporationInventors: Akira Furukawa, Kenichi Akita, Daisuke Sasaki
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Publication number: 20200400720Abstract: Magnetic sensors each disposed to face each of current paths for each of windings with 2n phases (n is a multiple of three) in an AC rotating machine are included, and when each of a DC component and an AC component in a d-axis sum current and a q-axis sum current obtained by performing a dq-transformation into a two-axis coordinate system on 2n detection currents on the assumption that all current amplitudes of the windings are the same is represented collectively with each of terms expressed by sine functions with different phases to one another, each of the current paths at each of 2n current path arrangement positions is arranged to have a positional relationship where error components are reduced by cancellation among coefficients included at least in one of the terms or by cancellation among values of the terms.Type: ApplicationFiled: April 22, 2020Publication date: December 24, 2020Applicant: Mitsubishi Electric CorporationInventors: Akira FURUKAWA, Kenichi AKITA, Daisuke SASAKI
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Publication number: 20200400722Abstract: Magnetic sensors each disposed to face each of current paths for each of windings with 2n phases (n is a multiple of three) in an AC rotating machine are included, and when each of a DC component and an AC component in a d-axis sum current and a q-axis sum current obtained by performing a dq-transformation into a two-axis coordinate system on 2n detection currents on the assumption that all current amplitudes of the windings are the same is represented collectively with each of terms expressed by sine functions with different phases, each of the current paths at each of 2n current path arrangement positions is arranged to have a positional relationship where error components are reduced by cancellation among coefficients included at least in one of the term or by cancellation among values of the terms.Type: ApplicationFiled: April 22, 2020Publication date: December 24, 2020Applicant: Mitsubishi Electric CorporationInventors: Akira Furukawa, Kenichi Akita, Daisuke Sasaki
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Patent number: 10840844Abstract: To provide a controller for a rotary electric machine capable of suppressing occurrence of an angle interval when the rotary electric machine cannot output torque, even if the ON angle interval of the switching devices is set smaller than 120 degrees in the rectangular wave control. A controller for a rotary electric machine performs a rectangular wave control to a rotary electric machine which has 2 groups of three-phase windings, with a phase difference between groups; and switches a first control mode and a second control mode according to a switching condition; wherein the first control mode is a mode which sets an ON angle interval to an angle within a range from 120 degrees to 180 degrees; and wherein the second control mode is a mode which sets the ON angle interval to an angle within a range from 90 degrees to 120 degrees.Type: GrantFiled: April 16, 2019Date of Patent: November 17, 2020Assignee: Mitsubishi Electric CorporationInventors: Kenichi Akita, Masahiko Fujita, Norio Matsumoto, Toshiyuki Yoshizawa, Mitsunori Tabata
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Publication number: 20190379235Abstract: The control device for an electric motor according to this application provides a battery voltage detecting part for detecting a battery voltage at the time of driving a motor driven by a battery, and a minimum voltage holding part for keeping the battery voltage above the predetermined voltage by reducing the consumption current of the electric motor when the battery voltage detected by the battery voltage detecting part falls below a predetermined voltage during driving of the electric motor, so that it is possible to suppress a reduction in battery voltage during driving at low cost, and it is possible to keep the battery voltage above the predetermined voltage.Type: ApplicationFiled: December 14, 2016Publication date: December 12, 2019Applicant: Mitsubishi Electric CorporationInventors: Nobuaki YOSHIOKA, Kenichi AKITA, Mitsunori TABATA
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Publication number: 20190372499Abstract: To provide a controller for a rotary electric machine capable of suppressing occurrence of an angle interval when the rotary electric machine cannot output torque, even if the ON angle interval of the switching devices is set smaller than 120 degrees in the rectangular wave control. A controller for a rotary electric machine performs a rectangular wave control to a rotary electric machine which has 2 groups of three-phase windings, with a phase difference between groups; and switches a first control mode and a second control mode according to a switching condition; wherein the first control mode is a mode which sets an ON angle interval to an angle within a range from 120 degrees to 180 degrees; and wherein the second control mode is a mode which sets the ON angle interval to an angle within a range from 90 degrees to 120 degrees.Type: ApplicationFiled: April 16, 2019Publication date: December 5, 2019Applicant: Mitsubishi Electric CorporationInventors: Kenichi AKITA, Masahiko Fujita, Norio Matsumoto, Toshiyuki Yoshizawa, Mitsunori Tabata
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Patent number: 10498272Abstract: A field circuit includes a positive pole side switching element which is for controlling field current that flows in a field winding and a negative pole side switching element which is for interrupting the field current; a field circuit control section includes a field high-speed interruption determination block and a field current interruption speed control block; and at the time of interrupting the field current at a high speed, the field current is interrupted immediately by turning OFF both switching elements of the positive pole side and the negative pole side and interruption speed of the field current is controlled by intermittently driving the negative pole side switching element.Type: GrantFiled: November 2, 2017Date of Patent: December 3, 2019Assignee: Mitsubishi Electric CorporationInventors: Takanori Matsunaga, Ryo Nakamura, Kenichi Akita
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Publication number: 20180351493Abstract: A field circuit includes a positive pole side switching element which is for controlling field current that flows in a field winding and a negative pole side switching element which is for interrupting the field current; a field circuit control section includes a field high-speed interruption determination block and a field current interruption speed control block; and at the time of interrupting the field current at a high speed, the field current is interrupted immediately by turning OFF both switching elements of the positive pole side and the negative pole side and interruption speed of the field current is controlled by intermittently driving the negative pole side switching element.Type: ApplicationFiled: November 2, 2017Publication date: December 6, 2018Applicant: Mitsubishi Electric CorporationInventors: Takanori MATSUNAGA, Ryo NAKAMURA, Kenichi AKITA
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Patent number: 9780694Abstract: Provided is a power converter capable of reliably turning OFF a switching element before turn-OFF of a diode even with a fluctuation in rpm so as not to generate a backflow of a current. The power converter includes a diode ON-interval monitoring unit (18) configured to measure a change rate of a diode ON detection interval signal. When a diode ON detection interval change rate signal (S20) exhibits a decrease on a negative side and is smaller than a predetermined value (an absolute value thereof exceeds a predetermined value), an OFF-timing of the switching element is advanced by a predetermined value or larger, to thereby reliably turn OFF the switching element before the turn-OFF of the diode even with the fluctuation in rpm.Type: GrantFiled: April 7, 2014Date of Patent: October 3, 2017Assignee: Mitsubishi Electric CorporationInventors: Junji Tada, Kenichi Akita, Katsuya Tsujimoto, Keiichi Komurasaki
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Patent number: 9755557Abstract: A field current limiting section includes a field current limitation instructing section for, when a field current limitation determining section determines that a determination value has reached a predetermined determination threshold value, generating a field current limiting instruction to a field current control section so as to limit field current to be equal to or smaller than a predetermined permissible value during a predetermined field current limitation time Tlim. A field current limitation releasing section outputs a field current limitation releasing instruction to the field current limiting section so as to release limitation of the field current during a predetermined field current limitation release time TC. When having received the field current limitation releasing instruction from the field current limitation releasing section, the field current limiting section releases limitation of the field current during the predetermined field current limitation release time.Type: GrantFiled: September 19, 2012Date of Patent: September 5, 2017Assignee: Mitsubishi Electric CorporationInventors: Kenichi Akita, Masato Mori, Mitsunori Tabata
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Publication number: 20170005593Abstract: Provided is a power converter capable of reliably turning OFF a switching element before turn-OFF of a diode even with a fluctuation in rpm so as not to generate a backflow of a current. The power converter includes a diode ON-interval monitoring unit (18) configured to measure a change rate of a diode ON detection interval signal. When a diode ON detection interval change rate signal (S20) exhibits a decrease on a negative side and is smaller than a predetermined value (an absolute value thereof exceeds a predetermined value), an OFF-timing of the switching element is advanced by a predetermined value or larger, to thereby reliably turn OFF the switching element before the turn-OFF of the diode even with the fluctuation in rpm.Type: ApplicationFiled: April 7, 2014Publication date: January 5, 2017Applicant: Mitsubishi Electric CorporationInventors: Junji TADA, Kenichi AKITA, Katsuya TSUJIMOTO, Keiichi KOMURASAKI
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Patent number: 9533580Abstract: Provided are a power converter for a vehicle generator-motor and a method for controlling a vehicle generator-motor, which is used for a field winding type vehicle generator-motor configured to perform control in accordance with an external operating command in which a power converter is connected to a rotating electrical machine including a field winding and an armature winding. When the generator-motor shifts from a driving state to another operating mode, a method of stopping a driving mode is switched in accordance with an operating mode to be shifted, to thereby shift the operating mode promptly without generating an unintended power generation, an excess power generation, and an excess torque fluctuation.Type: GrantFiled: March 7, 2012Date of Patent: January 3, 2017Assignee: Mitsubishi Electric CorporationInventors: Mitsunori Tabata, Masato Mori, Kenichi Akita
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Patent number: 9444380Abstract: A control section is configured to, when it is detected that a voltage of a B-terminal of a power generator has exceeded a first predetermined voltage value, turn on all switching elements of a negative arm of a bridge circuit connected to one set of armature windings and turn off all switching elements of a positive arm, and reduce a field current flowing in a field winding. The control section is configured to thereafter turn off all the turned-on switching elements when a predetermined condition is satisfied.Type: GrantFiled: December 15, 2011Date of Patent: September 13, 2016Assignee: Mitsubishi Electric CorporationInventors: Mitsunori Tabata, Masato Mori, Kenji Nakajima, Kenichi Akita
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Patent number: 9294025Abstract: A field winding rotating electrical machine includes a field current detection section, a field current control section configured to calculate a duty ratio of a current supplied to the field winding based on a field current detection value, to thereby control current supply to the field winding by using a switching element, and a field current correction section configured to estimate a time point when the field current becomes 0 A based on a control state of the field current, to specify the field current detection value at the estimated time point to be a field current correction value, and to subtract the field current correction value from the field current detection value, to thereby calculate the corrected field current value. The field current control section controls the current supply based on the corrected field current value calculated by the field current correction section.Type: GrantFiled: May 15, 2012Date of Patent: March 22, 2016Assignee: Mitsubishi Electric CorporationInventors: Kenichi Akita, Masato Mori, Mitsunori Tabata
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Patent number: 9117849Abstract: A method and apparatus of forming a nonvolatile semiconductor device including forming a first gate insulating film on a main surface of a first semiconductor region, forming a first gate electrode on the first gate insulating film, forming a second gate insulating film, forming a second gate electrode over a first side surface of the first gate electrode, selectively removing the second gate insulating film, etching the second gate insulating film kept between the second gate electrode and a main surface of the first semiconductor region in order to form an etched charge storage layer, introducing first impurities in the first semiconductor region in a self-aligned manner to the second gate electrode in order to form a second semiconductor region, annealing the semiconductor substrate to extend the second semiconductor region to an area under the second gate electrode.Type: GrantFiled: July 8, 2014Date of Patent: August 25, 2015Assignee: Renesas Electronics CorporationInventors: Kenichi Akita, Daisuke Okada, Keisuke Kuwahara, Yasufumi Morimoto, Yasuhiro Shimamoto, Kan Yasui, Tsuyoshi Arigane, Tetsuya Ishimaru
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Patent number: 9065379Abstract: Provided are a low-cost control device and the like for a vehicle generator-motor for minimizing the number of current sensors and the like, and estimating an output torque and a current consumption during drive of the generator-motor. The output torque and the current consumption during the drive of the generator-motor are estimated based on a field current, an rpm, a DC voltage, and a phase of an AC voltage to be supplied of the generator-motor, without providing a current sensor for detecting an input current from a power supply to an inverter device of the generator-motor, and a current sensor for detecting an output current from the inverter device to an armature winding of a rotary electric machine.Type: GrantFiled: October 15, 2013Date of Patent: June 23, 2015Assignee: Mitsubishi Electric CorporationInventors: Mitsunori Tabata, Masato Mori, Kenichi Akita
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Patent number: 9024284Abstract: A superlattice phase change memory capable of increasing a resistance in a low resistance state is provided. The phase change memory includes a first electrode, a second electrode provided on the first electrode, and a phase change memory layer having a superlattice structure between the first electrode and the second electrode, the superlattice structure including to repeatedly formed layers of Sb2Te3 and GeTe. The phase change memory layer having the superlattice structure includes a Sb2Te3 layer containing Zr in contact with the first electrode.Type: GrantFiled: November 27, 2013Date of Patent: May 5, 2015Assignee: Hitachi, Ltd.Inventors: Takasumi Oyanagi, Norikatsu Takaura, Mitsuharu Tai, Masaharu Kinoshita, Takahiro Morikawa, Kenichi Akita, Masahito Kitamura
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Publication number: 20150091534Abstract: A field current limiting section includes a field current limitation instructing section for, when a field current limitation determining section determines that a determination value has reached a predetermined determination threshold value, generating a field current limiting instruction to a field current control section so as to limit field current to be equal to or smaller than a predetermined permissible value during a predetermined field current limitation time Tlim. A field current limitation releasing section outputs a field current limitation releasing instruction to the field current limiting section so as to release limitation of the field current during a predetermined field current limitation release time TC. When having received the field current limitation releasing instruction from the field current limitation releasing section, the field current limiting section releases limitation of the field current during the predetermined field current limitation release time.Type: ApplicationFiled: September 19, 2012Publication date: April 2, 2015Applicant: MITSUBISHI ELECTRIC CORPORATIONInventors: Kenichi Akita, Masato Mori, Mitsunori Tabata