Patents by Inventor Toshiaki Okuyama
Toshiaki Okuyama 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: 7869232Abstract: An electric power converter apparatus having a function of converting a power source voltage into an AC voltage having an arbitrary frequency and maintaining an output voltage constant even on the power source variation, in which the electric power converter apparatus decreases the output voltage when the output voltage drops to equal to or less than a predetermined value, afterward, increases the output voltage in response to a predetermined rate of change when the power source voltage rises.Type: GrantFiled: August 22, 2007Date of Patent: January 11, 2011Assignee: Hitachi, Ltd.Inventors: Koichiro Nagata, Toshiaki Okuyama, Shigetoshi Okamatsu, Koichi Miyazaki
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Patent number: 7671558Abstract: The present invention provides an induction motor controller which includes: a circuit for generating a d-axis current reference signal from a d-axis current command value and a periodically varying periodic signal; a d-axis current controller for controlling a d-axis motor current flowing through an induction motor to be controlled to match the d-axis current reference signal; parameter determining means for calculating and determining a motor parameter of the induction motor based on a deviation of the d-axis motor current from the d-axis current reference signal, and controlling a voltage applied to the induction motor using a compensation voltage calculated from the calculated and determined motor parameter, in which a control parameter for controlling the induction motor is set based on the calculated and determined motor parameter.Type: GrantFiled: August 23, 2007Date of Patent: March 2, 2010Assignee: Hitachi Industrial Equipment Systems Co., Ltd.Inventors: Kouki Yamamoto, Toshiaki Okuyama, Hiroyuki Tomita, Yoshitaka Iwaji, Koichiro Nagata
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Patent number: 7545116Abstract: An object of the present invention is to provide a driver for an induction motor which performs an operation at an acceleration suitable for the magnitude of a load and is excellent in efficiency, without an acceleration failure. The driver for an induction motor includes a slip frequency estimate value arithmetic operation section 15 for arithmetically operating a slip frequency ?s^ of an induction motor 12, and a maximum torque generation slip arithmetic operation section 16 for arithmetically operating a slip frequency ?smax at which a maximum torque is generated. When the slip frequency ?s^ exceeds a predetermined value ?smaxTH (=0.9 ?smax, etc.) corresponding to the slip frequency ?smax at which the maximum torque is generated, a speed change rate arithmetic operation section 17 and a speed change rate correcting section 18 reduce a rate of increase in a speed command ?r*.Type: GrantFiled: January 25, 2007Date of Patent: June 9, 2009Assignee: Hitachi Industrial Equipment Systems Co., Ltd.Inventors: Koichiro Nagata, Toshiaki Okuyama, Kouki Yamamoto, Hiroyuki Tomita
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Publication number: 20080169783Abstract: The present invention provides an induction motor controller which includes: a circuit for generating a d-axis current reference signal from a d-axis current command value and a periodically varying periodic signal; a d-axis current controller for controlling a d-axis motor current flowing through an induction motor to be controlled to match the d-axis current reference signal; parameter determining means for calculating and determining a motor parameter of the induction motor based on a deviation of the d-axis motor current from the d-axis current reference signal, and controlling a voltage applied to the induction motor using a compensation voltage calculated from the calculated and determined motor parameter, in which a control parameter for controlling the induction motor is set based on the calculated and determined motor parameter.Type: ApplicationFiled: August 23, 2007Publication date: July 17, 2008Inventors: KOUKI YAMAMOTO, Toshiaki Okuyama, Hiroyuki Tomita, Yoshitaka Iwaji, Koichiro Nagata
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Publication number: 20080088291Abstract: An electric power converter apparatus having a function of converting a power source voltage into an AC voltage having an arbitrary frequency and maintaining an output voltage constant even on the power source variation, in which the electric power converter apparatus decreases the output voltage when the output voltage drops to equal to or less than a predetermined value, afterward, increases the output voltage in response to a predetermined rate of change when the power source voltage rises.Type: ApplicationFiled: August 22, 2007Publication date: April 17, 2008Inventors: Koichiro Nagata, Toshiaki Okuyama, Shigetoshi Okamatsu, Koichi Miyazaki
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Patent number: 7332888Abstract: A motor driving apparatus includes: a current instruction calculator, for calculating a current instruction value based on a deviation between a speed instruction value and an estimated speed value; a current controller, for controlling an output current based on the current instruction value; a frequency instruction calculator, for calculating a frequency instruction value based on an output voltage instruction value or an output voltage detection value, wherein, when an induction motor is to be activated, the current instruction value and the frequency instruction value are calculated directly using the speed instruction value, and an output current and an output frequency are controlled in accordance with the current instruction value and the frequency instruction value.Type: GrantFiled: February 23, 2006Date of Patent: February 19, 2008Assignee: Hitachi, Ltd.Inventors: Koichiro Nagata, Toshiaki Okuyama, Haruo Nemoto, Toshio Katayama
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Publication number: 20070210741Abstract: An object of the present invention is to provide a driver for an induction motor which performs an operation at an acceleration suitable for the magnitude of a load and is excellent in efficiency, without an acceleration failure. The driver for an induction motor includes a slip frequency estimate value arithmetic operation section 15 for arithmetically operating a slip frequency ?s? of an induction motor 12, and a maximum torque generation slip arithmetic operation section 16 for arithmetically operating a slip frequency ?smax at which a maximum torque is generated. When the slip frequency ?s? exceeds a predetermined value ?smaxTH(=0.96?smax, etc.) corresponding to the slip frequency ?smax at which the maximum torque is generated, a speed change rate arithmetic operation section 17 and a speed change rate correcting section 18 reduce a rate of increase in a speed command ?r*.Type: ApplicationFiled: January 25, 2007Publication date: September 13, 2007Inventors: Koichiro Nagata, Toshiaki Okuyama, Kouki Yamamoto, Hiroyuki Tomita
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Publication number: 20060192521Abstract: A motor driving apparatus includes: a current instruction calculator, for calculating a current instruction value based on a deviation between a speed instruction value and an estimated speed value; a current controller, for controlling an output current based on the current instruction value; a frequency instruction calculator, for calculating a frequency instruction value based on an output voltage instruction value or an output voltage detection value, wherein, when an induction motor is to be activated, the current instruction value and the frequency instruction value are calculated directly using the speed instruction value, and an output current and an output frequency are controlled in accordance with the current instruction value and the frequency instruction value.Type: ApplicationFiled: February 23, 2006Publication date: August 31, 2006Inventors: Koichiro Nagata, Toshiaki Okuyama, Haruo Nemoto, Toshio Katayama
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Patent number: 6844700Abstract: An inverter apparatus for converting a DC power converted from an input AC power to an output AC power of a variable frequency and a variable electric power to drive an induction motor at a variable speed. The inverter apparatus includes a rectifying unit, a filter capacitor, an inverter unit having an input connected across the filter capacitor, an input current detector and a gate circuitry for driving the inverter unit. An excitation current detection unit detects an excitation current of the induction motor from an output signal of the input current detector, a gate signal for driving the gate circuitry and a reference phase command. A setting unit sets a limitation level of the excitation current, a torque boost voltage command unit produces a torque boost voltage command, and a torque boost voltage compensation unit changes the torque boost voltage command so that the detected excitation current value is smaller than or equal to the limitation level.Type: GrantFiled: July 8, 2003Date of Patent: January 18, 2005Assignee: Hitachi, Ltd.Inventors: Keijiro Sakai, Toshiaki Okuyama, Kinya Nakatsu, Hiroyuki Tomita, Junji Kato, Teiichi Furukawa
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Patent number: 6841911Abstract: A machine tool provided with an electric motor which can maintain the fixed output power in a wide speed range. The electric motor has a stator having a primary winding, and a rotor having a field magnet and a shaft, said field magnet comprising a first field magnet having different polarity magnetic poles sequentially arranged in a rotating direction and a second field magnet having different polarity magnetic poles sequentially arranged in a rotating direction, and a mechanism for shifting one field magnet in axial and rotating directions with respect to the other field magnet, whereby a composite magnetic field of said first and said second field magnets is changed.Type: GrantFiled: February 27, 2002Date of Patent: January 11, 2005Assignee: Hitachi, Ltd.Inventors: Houng Joong Kim, Toshiaki Okuyama
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Patent number: 6741063Abstract: Induction voltage command Em* is obtained from inverter's primary frequency command &ohgr;1* and torque boost voltage commander produces torque boost voltage command &Dgr;Vz* in accordance with &ohgr;1* while integrator produces reference phase command &thgr;d*. uvw/dq converter detects motor excitation current Id (equivalent of no-load current). Next, deviation of excitation current limitation level command Idmax* and detected Id is inputted to limiter processing unit to produce torque boost voltage compensation value &Dgr;Vc for varying &Dgr;Vz* so that Id is smaller than or equal to Idmax*. Inverted &Dgr;Vz* is set up as a lower limiter value of the limiter processing unit. Next, &Dgr;Vc and &Dgr;Vz* are added to produce final compensated torque boost voltage command &Dgr;Vt* and &Dgr;Vt* and Em* are added to produce q-axis voltage command Vq* of the inverter output voltage.Type: GrantFiled: March 19, 2002Date of Patent: May 25, 2004Assignee: Hitachi, Ltd.Inventors: Keijiro Sakai, Toshiaki Okuyama, Kinya Nakatsu, Hiroyuki Tomita, Junji Kato, Teiichi Furukawa
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Patent number: 6704212Abstract: In calculation 3 phase AC output current Iu, Iv,Iw of an inverter based on the input DC current Idc of the inverter, it is difficult to detect the DC current Idc when the line-to-line voltage pulse width is narrow, thereby the DC current Idc pulse width becomes narrower. The frequency Fc of the carrier wave C is lowered in a phase whose line-to-line voltage is high, thereby the DC current Idc pulse width is set wider. As a result, the current detection is enabled.Type: GrantFiled: August 16, 2002Date of Patent: March 9, 2004Assignees: Hitachi, Ltd., Hitachi Keiyo Engineering & System, Ltd.Inventors: Teiichi Furukawa, Masahiro Hiraga, Hiroyuki Tomita, Seiji Ishida, Toshiaki Okuyama
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Publication number: 20040008005Abstract: An inverter apparatus for converting a DC power converted from an input AC power to an output AC power of a variable frequency and a variable electric power to drive an induction motor at a variable speed. The inverter apparatus includes a rectifying unit, a filter capacitor, an inverter unit having an input connected across the filter capacitor, an input current detector and a gate circuitry for driving the inverter unit. An excitation current detection unit detects an excitation current of the induction motor from an output signal of the input current detector, a gate signal for driving the gate circuitry and a reference phase command. A setting unit sets a limitation level of the excitation current, a torque boost voltage command unit produces a torque boost voltage command, and a torque boost voltage compensation unit changes the torque boost voltage command so that the detected excitation current value is smaller than or equal to the limitation level.Type: ApplicationFiled: July 8, 2003Publication date: January 15, 2004Inventors: Keijiro Sakai, Toshiaki Okuyama, Kinya Nakatsu, Hiroyuki Tomita, Junji Kato, Teiichi Furukawa
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Patent number: 6670786Abstract: If a speed instruction value is less than a predetermined value, the output current of a power-conversion unit is controlled to be larger than a current value in an ordinary no-load operation, or a frequency instruction value is calculated based on a speed instruction value in place of an estimated speed.Type: GrantFiled: December 7, 2001Date of Patent: December 30, 2003Assignee: Hitachi, Ltd.Inventors: Kazuaki Tobari, Toshiaki Okuyama
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Patent number: 6657412Abstract: In detecting an output current of a power converter based on a DC current Idc of the power converter, the pulse width of the DC current Idc becomes narrower when the pulse width of a line voltage is narrower, and its detection becomes difficult. A voltage command correction unit 9 according to the present invention corrects voltage commands such that pulse width of a line voltage becomes zero when the pulse width of the line voltage is less than the minimum pulse width, not to output a line pulse, and an error generated by the correction is integrated. This integrated error is added to the line voltage in the next time, and the integrated pulse width of the line voltage is outputted when the pulse width becomes larger than or equal to the minimum pulse width.Type: GrantFiled: August 30, 2001Date of Patent: December 2, 2003Assignee: Hitachi, Ltd.Inventors: Seiji Ishida, Keijiro Sakai, Toshiaki Okuyama, Hiroshi Fujii, Hiroyuki Tomita, Tatsuo Ando, Yuhachi Takakura, Hideo Kimura
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Patent number: 6646896Abstract: For use in a system in which a capacitor is connected between an AC machine and an inverter in order to improve the power factor, a controller for an AC machine capable of even when the overvoltage occurs due to the self-excitation between the AC machine and the capacitor, reactivating stably the inverter to continue the running. When the operation of the inverter is stopped and then the inverter is reactivated, the manipulation of starting the switching of the inverter is performed after a DC voltage of the inverter has been decreased to the operating voltage in the running, whereby the reactivation is performed stably without stopping the system.Type: GrantFiled: March 15, 2002Date of Patent: November 11, 2003Assignee: Hitachi, Ltd.Inventors: Yoshitoshi Akita, Toshiaki Okuyama, Koichiro Nagata, Shigetoshi Okamatsu
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Patent number: 6642689Abstract: Filter capacitor voltage “Ecf1” is detected and then after d-axis voltage correction value “dvd”, q-axis voltage correction value “dvq”, q-axis current correction value “diq”, and frequency correction value “d&ohgr;1” have been computed from the AC components of “Ecf1” and the results have been added to the corresponding d-axis voltage command, q-axis voltage command, q-axis current, and frequency command, the DC current of the power converter is controlled. Thus, the AC components included in the DC current are offset and the AC components are suppressed effectively.Type: GrantFiled: September 20, 2001Date of Patent: November 4, 2003Assignee: Hitachi, Ltd.Inventors: Seiji Ishida, Toshiaki Okuyama, Takashi Ogawa, Tetsuo Kojima, Kiyoshi Nakata
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Patent number: 6633495Abstract: The voltage applied to a power converter is detected by a voltage detector, a function generator produces a voltage proportional to this detected voltage, and a high-pass filter detects an AC component superimposed on the voltage. An adder adds a bias voltage to this AC component, and an adder adds the output from the adder and the output from the function generator. The output from the adder is compared with a triangular wave produced from a rectangular wave generator, and a switching element is controlled to make switching operation according to the compared result. When a DC current is decreased by the AC component, a resistance current Ib is increased so that the AC components superimposed on the current and resistance current can be cancelled out.Type: GrantFiled: March 20, 2002Date of Patent: October 14, 2003Assignee: Hitachi, Ltd.Inventors: Seiji Ishda, Toshiaki Okuyama, Tetsuo Kojima, Kiyoshi Nakata, Akira Horie
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Patent number: 6611125Abstract: An electric motor is rotated at a velocity &ohgr;1. After that, during &Dgr;t12 seconds, the 1st acceleration is executed at a rate (&ohgr;2−&ohgr;1)/&Dgr;t12. During this acceleration, the torque &tgr;m is calculated so as to execute the time integration. After the lapse of &Dgr;t12, the integrated result is stored. Next, the velocity is set to be &ohgr;3. After that, during &Dgr;t34 seconds, the 2nd acceleration is executed at a rate (&ohgr;4−&ohgr;3)/&Dgr;t34. At the 2nd acceleration, although the integration-starting and the integration-terminating velocities are each equal to those at the 1st acceleration, the acceleration rate is modified (&ohgr;3=&ohgr;1, &ohgr;4=&ohgr;2, &Dgr;t12≠&Dgr;t34). During this acceleration, the torque &tgr;m is calculated so as to execute the time integration, after the lapse of &Dgr;t34, storing the integrated result. The inertia J is calculated using the 1st and 2nd integrated results.Type: GrantFiled: February 26, 2001Date of Patent: August 26, 2003Assignee: Hitachi, Ltd.Inventors: Koichiro Nagata, Toshiaki Okuyama, Hiroshi Fujii, Shigetoshi Okamatsu
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Publication number: 20030142517Abstract: In calculation 3 phase AC output current Iu, Iv,Iw of an inverter based on the input DC current Idc of the inverter, it is difficult to detect the DC current Idc when the line-to-line voltage pulse width is narrow, thereby the DC current Idc pulse width becomes narrower.Type: ApplicationFiled: August 16, 2002Publication date: July 31, 2003Applicant: Hitachi, Ltd.Inventors: Teiichi Furukawa, Masahiro Hiraga, Hiroyuki Tomita, Seiji Ishida, Toshiaki Okuyama