Patents by Inventor Yoshitaka Iwaji
Yoshitaka Iwaji 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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Publication number: 20130088099Abstract: To provide a linear generator according to the present invention where a load onto a supporting mechanism and the ripple of force are reduced, the pitch of a magnetic pole is narrowed and a high frequency is acquired, the linear generator according to the present invention is provided with plural magnetic poles arranged with the magnets arranged on a mover held between the plural magnetic poles, a core that continuously connects the magnetic poles which hold the magnets of the mover between them, winding integrally wound onto the plural magnetic poles and the mover configured by a row of magnets in which the magnetic poles of the magnets are alternately arranged or a row of magnets in which the polarity of magnets is alternately arranged and magnetic materials, the magnetic pole arranged with the magnets held between the magnetic poles and the magnetic pole provided with the core that continuously connects the magnetic poles which hold the magnets are arranged in a longitudinal direction of the mover by pluraType: ApplicationFiled: June 9, 2010Publication date: April 11, 2013Applicant: Hitachi, Ltd.Inventors: Yasuaki Aoyama, Yoshitaka Iwaji
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Patent number: 8410735Abstract: A torque ripple suppression control device for a permanent magnet motor includes a current command conversion unit that outputs a current command value, a position detector that detects a rotational position of the permanent magnet motor, a current detection unit that detects a current at the permanent magnet motor, an induced voltage coefficient setting unit that outputs an information signal related to an induced voltage coefficient for an induced voltage at the permanent magnet motor, a torque ripple suppression operation unit that outputs a current correction command value for the permanent magnet motor, a current control operation unit that outputs a voltage command value based upon addition results obtained by adding together the current command value and the current correction command value and the current detection value, and a power converter that outputs a voltage with which the permanent magnet motor is to be driven.Type: GrantFiled: January 19, 2011Date of Patent: April 2, 2013Assignee: Kokusan Denki Co., Ltd.Inventors: Kazuaki Tobari, Yoshitaka Iwaji, Junnosuke Nakatsugawa, Rikio Yoshikawa, Masamichi Yagai
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Publication number: 20130057193Abstract: In sequentially selecting and driving two phases of the three-phase stator windings of a synchronous motor, detect a speed electromotive voltage of a de-energized phase, relate the speed electromotive voltage to rotor position information beforehand, then count rotor position information backward based on the detected the speed electromotive voltage to estimate rotor position; and then detect rotation speed from the change rate of the rotor position information so as to achieve highly accurate position and speed control.Type: ApplicationFiled: July 26, 2012Publication date: March 7, 2013Applicant: Hitachi Automotive Systems, Ltd.Inventors: Yoshitaka Iwaji, Shigehisa Aoyagi, Kazuaki Tobari, Ryoichi Takahata, Masaki Hano
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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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Publication number: 20120146567Abstract: To prevent demagnetization of a permanent magnet synchronous rotating machine, a rotating machine control device according to the present invention is a rotating machine control device comprising: a power converter having a switch part on each of a positive side and a negative side for each phase; and short circuit detection unit for detecting a short circuit of the switch part, wherein a command to turn on positive-side switches and negative-side switches of a plurality of phases of the switch part is issued in the case where the short circuit detection unit detects the short circuit.Type: ApplicationFiled: December 12, 2011Publication date: June 14, 2012Applicant: Hitachi, Ltd.Inventors: Yoshitaka IWAJI, Daigo Kaneko, Kento Mochizuki, Takeshi Shinomiya, Daisuke Kori, Seikichi Masuda
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Publication number: 20120038301Abstract: Provided is an AC motor in a three-phase unbalanced state such as a claw-teeth type AC motor (108), which is reduced in magnetic flux pulsations and torque pulsations. Among the current command values of individual phases to be intrinsically given to an inverter (106) for feeding three-phase alternating currents of variable voltages/frequencies to the electric motor, a current command of an intermediate phase (a V-phase) having a smaller magnetic resistance of a stator core than those of other phases is subjected to a reducing correction by a correction unit (102) on the basis of the correction amount calculated by a current correction amount calculating unit (103), and the unbalanced three-phase alternating currents are fed to the AC motor (108), so that magnetic flux pulsations of a secondary electric angle and torque pulsations of the same order are reduced.Type: ApplicationFiled: April 16, 2009Publication date: February 16, 2012Applicant: Hitachi LtdInventors: Norihisa Iwasaki, Junnosuke Nakatsugawa, Yoshitaka Iwaji
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Publication number: 20120007528Abstract: The present invention relates to an AC motor control device and, particularly, to provide an AC control device capable of simply setting a state quantity of an AC motor non-linearly variable, in accordance with the motor driving state and using the setting in motor control, the present invention can be achieved by including a state quantity calculating unit (13, 13a, 13b, 13c) for calculating a state quantity corresponding to a coil interlinkage flux which is an internal quantity of the motor, calculating a setting value of the coil interlinkage flux defined on one axis out of two axes, that is, d and q axes, with a function formula using a current defined on the same one of the axes and a function formula using a state variable defined on the other one of the axes.Type: ApplicationFiled: February 26, 2010Publication date: January 12, 2012Inventors: Junnosuke Nakatsugawa, Yoshitaka Iwaji, Norihisa Iwasaki, Hirokazu Nagura
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Publication number: 20110298308Abstract: Provided is a small size and lightweight linear motor having small thrust ripples, in which the magnetic attraction working between an armature and a mover is canceled out and therefore is small. A thrust generation mechanism comprises a stator (3) and a mover (5). The mover (5) includes permanent magnets (4) installed in a row so that the magnetic poles at the front and backsides of the magnets are alternately reversed along the traveling direction. The stator (3) includes upper and lower pole teeth (6), (7) having a plurality of magnetic poles (2) and arranged so as to sandwich the permanent magnets (4) of the mover (5), cores for connecting the pole teeth, and a winding (1) wound around a set of a plurality of the cores. Thrust ripples are reduced by adjusting the magnetic pole pitch (Pc) of the magnetic poles (2).Type: ApplicationFiled: March 13, 2009Publication date: December 8, 2011Inventors: Yasuaki Aoyama, Yoshitaka Iwaji
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Patent number: 8044618Abstract: It is attained by being provided with a motor constant calculation unit for calculating electric constants of a motor, and by correcting setting values of electric constants defined on one of the axes of two orthogonal axes, by a functional expression using a state variable defined on the same axis, and by correcting them by a functional expression using a state variable defined on the other axis.Type: GrantFiled: November 25, 2008Date of Patent: October 25, 2011Assignee: Hitachi, Ltd.Inventors: Junnosuke Nakatsugawa, Yoshitaka Iwaji, Kazuaki Tobari, Kiyoshi Sakamoto
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Publication number: 20110241449Abstract: A thrust generation mechanism comprising magnetic pole teeth which are arranged so as to sandwich and hold permanent magnets disposed on movers, cores which serially connect the magnetic pole teeth which sandwich and hold the magnets, armature winding wires which are collectively wound around the cores, and the movers having the magnets arranged such that the different magnetic poles thereof alternately face the front side and the rear side. The magnetic pole teeth which are arranged so as to sandwich and hold the permanent magnets and the armature iron cores which have cores serially connecting the magnetic pole teeth which hold the magnets are arranged in the longitudinal direction of the movers, and armature iron cores have a common winding wire.Type: ApplicationFiled: December 10, 2009Publication date: October 6, 2011Inventors: Yasuaki Aoyama, Yoshitaka Iwaji
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Publication number: 20110234133Abstract: The present invention relates to a drive apparatus and drive method for switching an energization mode when a voltage of a non-energized phase of a brushless motor crosses a threshold. In threshold learning, first, the brushless motor is stopped at an initial position. The brushless motor is then rotated by performing phase energization based on the energization mode from the stopped state. The voltage of the non-energized phase at an angular position of switching the energization mode is detected from a maximum value or a minimum value of the voltage of the non-energized phase during the rotation, and the threshold is learned based on the detected voltage. Alternatively, the brushless motor is positioned at the angular position of switching the energization mode by maintaining one energization mode, and then the energization mode is switched to the next energization mode.Type: ApplicationFiled: March 21, 2011Publication date: September 29, 2011Inventors: Masaki Hano, Yoshitaka Iwaji, Shigehisa Aoyagi
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Publication number: 20110204831Abstract: Provided is a drive device for an alternating current motor which performs vector control on sensorless driving of the alternating current motor in an extremely low speed region without applying a harmonic voltage intentionally while maintaining an ideal PWM waveform. A current and a current change rate of the alternating current motor are detected, and a magnetic flux position inside of the alternating current motor is estimated and calculated in consideration of an output voltage of an inverter which causes this current change. The current change rate is generated on the basis of a pulse waveform of the inverter, and hence the magnetic flux position inside of the alternating current motor can be estimated and calculated without applying a harmonic wave intentionally.Type: ApplicationFiled: February 18, 2011Publication date: August 25, 2011Inventors: Yoshitaka Iwaji, Daigo Kaneko, Kouki Yamamoto
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Publication number: 20110175556Abstract: A torque ripple suppression control device for a permanent magnet motor includes a current command conversion unit that outputs a current command value, a position detector that detects a rotational position of the permanent magnet motor, a current detection unit that detects a current at the permanent magnet motor, an induced voltage coefficient setting unit that outputs an information signal related to an induced voltage coefficient for an induced voltage at the permanent magnet motor, a torque ripple suppression operation unit that outputs a current correction command value for the permanent magnet motor, a current control operation unit that outputs a voltage command value based upon addition results obtained by adding together the current command value and the current correction command value and the current detection value, and a power converter that outputs a voltage with which the permanent magnet motor is to be driven.Type: ApplicationFiled: January 19, 2011Publication date: July 21, 2011Inventors: Kazuaki TOBARI, Yoshitaka Iwaji, Junnosuke Nakatsugawa, Rikio Yoshikawa, Masamichi Yagai
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Patent number: 7919941Abstract: A semiconductor power converter includes a power converter for converting direct current to three-phase alternating current or vice versa; a means for detecting a current in an alternating current side of the power converter; a means for providing a current reference in the alternating current side of the power converter; a current controller for calculating a voltage reference in the alternating current side of the power converter to match the current reference and a value of the detected current; and a pulse width modulation means for controlling the power converter through pulse width modulation based on the voltage reference, wherein the current reference is used in place of the value of the detected current for at least one phase current among three phase currents in the alternating current side.Type: GrantFiled: August 18, 2008Date of Patent: April 5, 2011Assignees: Hitachi, Ltd., Hitachi Car Engineering Co., Ltd., Hitachi Industrial Equipment Systems Co., Ltd.Inventors: Shigehisa Aoyagi, Yoshitaka Iwaji, Kazuaki Tobari, Kiyoshi Sakamoto, Donsheng Li
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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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Publication number: 20110050140Abstract: When applying a high frequency voltage which alternates on positive and negative sides to a permanent magnet synchronous motor, a driving system of synchronous motor switches the applied voltage phase by 120 degrees successively and applies resultant voltages to three phases. A pulsating current generated by applying a high frequency voltage is detected at timing of elapse of a predetermined time ?t since an output voltage of at least one phase has changed from a state in which all output voltages of the three phases of a power converter are positive or negative. Current detection is conducted by using a DC resistor or a phase current sensor provided on a DC bus. A magnetic pole estimation unit calculates the rotor magnetic pole position of the permanent magnet synchronous motor on the basis of differences between positive side and negative side change quantities in three-phase currents obtained from detected current values.Type: ApplicationFiled: August 20, 2010Publication date: March 3, 2011Inventors: Toshifumi Sakai, Yoshitaka Iwaji, Kiyoshi Sakamoto, Yoshiyuki Taguchi, Daigo Kaneko
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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: 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