Patents by Inventor Shigehisa Aoyagi
Shigehisa Aoyagi 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: 8710781Abstract: In a power conversion device that includes a PWM converting means for generating a PWM pulse by comparing three-phase voltage commands with a triangular wave carrier signal, a power converter for converting between a DC voltage and a three-phase AC voltage by driving a switching element according to the PWM pulse, a current detecting means for detecting a pulsed current flowing through a DC bus conductor of a main circuit, and a voltage command correcting means for correcting three-phase voltage commands, which corrects the three-phase voltage commands so that a line voltage value between the maximum phase and an intermediate phase and a line voltage value between the intermediate phase and the minimum phase are each equal to or larger than a predetermined value, the maximum phase, intermediate phase, and minimum phase being determined in correspondence to momentary values of the three-phase voltage commands arranged in descending order, if the voltage command is outside an allowable upper limit or lower limiType: GrantFiled: February 17, 2010Date of Patent: April 29, 2014Assignee: Hitachi Industrial Equipment Systems Co., Ltd.Inventors: Yoichiro Arakawa, Koichiro Nagata, Yuusuke Arao, Shigehisa Aoyagi
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Publication number: 20140077738Abstract: A position sensor-less driving method is provided that can drive rotation speed/torque control of a permanent magnet motor using an inverter with an ideal sinusoidal current with the minimum number of switching, and can drive at a speed as low as an extremely low speed region close to zero speed. A neutral point potential of a permanent magnet motor is detected in synchronization with PWM waveform of the inverter. A rotor position of the permanent magnet motor is estimated from change of the neutral point potential. When the neutral point potential is detected, timing of each phase of the PWM waveform is shifted to generate three or four types of switch states of which output voltage of the inverter is not zero vector, and neutral point potentials in at least two types of switch states among them are sampled, whereby rotor position of the three-phase synchronous motor is estimated.Type: ApplicationFiled: May 13, 2011Publication date: March 20, 2014Applicant: Hitachi, Ltd.Inventors: Yoshitaka Iwaji, Shigehisa Aoyagi, Ryoichi Takahata, Kazuaki Tobari
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Publication number: 20130272899Abstract: A drive system of a synchronous electrical motor includes a synchronous electrical motor; a power converter that is connected to the motor with a plurality of switching elements; a controller that outputs a voltage instruction to the power converter; a voltage detection unit for open phases upon application of respective positive and negative pulse voltages between respective two phases out of three-phase windings of the motor; an induced voltage difference for calculating an induced voltage difference that is a difference between an induced voltage detected by the voltage detection unit at each of the open phases upon application of the positive voltage pulse between the corresponding two phases and an induced voltage detected by the voltage detection unit at the open phase upon application of the negative voltage pulse between the two phases.Type: ApplicationFiled: April 9, 2013Publication date: October 17, 2013Applicant: HITACHI AUTOMOTIVE SYSTEMS, LTD.Inventors: Ryoichi TAKAHATA, Yoshitaka IWAJI, Shigehisa AOYAGI, Kazuaki TOBARI
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Publication number: 20130243625Abstract: A synchronous electric motor drive system capable of driving at speeds near zero is provided. An energization mode determination unit switches six energization modes successively based on a terminal potential detected of the de-energized phase of a three-phase synchronous electric motor or on a stator winding wire connection point potential (neutral point potential) detected of the three-phase synchronous transmission unit. A voltage command correction unit corrects by a correction amount ?V an applied voltage command destined for the synchronous electric motor to supply the synchronous electric motor with a repeated waveform of a positive pulse, negative pulse, and zero voltage as a line voltage waveform of the energized phases in each of the six energization modes, the positive pulse voltage being polarized to cause the synchronous electric motor to generate a forward rotation torque, the negative pulse voltage causing the synchronous electric motor to generate a reverse rotation torque.Type: ApplicationFiled: July 26, 2011Publication date: September 19, 2013Applicants: Hitachi Car Engineering Co., Ltd., Hitachi Automotive Systems, Ltd.Inventors: Yoshitaka Iwaji, Shigehisa Aoyagi, Kazuaki Tobari, Ryoichi Takahata
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Patent number: 8436563Abstract: If magnitude relations between the output terminal voltage based on a DC negative terminal of the inverter and a threshold voltage that is a fixed value are compared, polarity thereof is changed at a predetermined rotor phase. The magnitude relation, for example, is detected by an inexpensive and simple apparatus such as a level shift circuit and a NOT circuit. The rotor phase of the permanent magnet synchronous motor is inferred on the basis of changes in the magnitude relation and if it is differentiated, a rotation speed is inferred. If the inferred values of the rotor phase and rotation speed are fed back to synchronous operation or vector control, the free-running permanent magnet synchronous motor is restarted.Type: GrantFiled: June 30, 2010Date of Patent: May 7, 2013Assignee: Hitachi, Ltd.Inventors: Satoshi Sumita, Kazuaki Tobari, Shigehisa Aoyagi, Daisuke Maeda
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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: 8305019Abstract: When output voltage V1 of an electric power converter reaches a prescribed voltage V1*ref, a difference between V1 and V1*ref is integrated to correct a commanded torque to ?o* (?*=?o*+??).Type: GrantFiled: February 18, 2010Date of Patent: November 6, 2012Assignee: Hitachi Car Engineering Co., Ltd.Inventors: Kazuaki Tobari, Shigehisa Aoyagi, Kentaro Oi
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Patent number: 8106619Abstract: In a calculation for estimating axis error in a permanent magnet motor, a d-axis commanded voltage value is added to the product of three signals, which are a q-axis detected current value or commanded current value, an inductance value, and an estimated speed value, and then the resulting value is divided by the product of a commanded speed value ?r* and induced voltage constant Ke* or an arctangent calculation is performed in the same way, instead of using a resistance setting.Type: GrantFiled: December 9, 2008Date of Patent: January 31, 2012Assignees: Hitachi Industrial Equipment Systems Co. Ltd., Hitachi Car Engineering Co., Ltd.Inventors: Kazuaki Tobari, Shigehisa Aoyagi
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Publication number: 20110292700Abstract: In a power conversion device that includes a PWM converting means for generating a PWM pulse by comparing three-phase voltage commands with a triangular wave carrier signal, a power converter for converting between a DC voltage and a three-phase AC voltage by driving a switching element according to the PWM pulse, a current detecting means for detecting a pulsed current flowing through a DC bus conductor of a main circuit, and a voltage command correcting means for correcting three-phase voltage commands, which corrects the three-phase voltage commands so that a line voltage value between the maximum phase and an intermediate phase and a line voltage value between the intermediate phase and the minimum phase are each equal to or larger than a predetermined value, the maximum phase, intermediate phase, and minimum phase being determined in correspondence to momentary values of the three-phase voltage commands arranged in descending order, if the voltage command is outside an allowable upper limit or lower limiType: ApplicationFiled: February 17, 2010Publication date: December 1, 2011Inventors: Yoichiro Arakawa, Koichiro Nagata, Yuusuke Arao, Shigehisa Aoyagi
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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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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: 20110006715Abstract: If magnitude relations between the output terminal voltage based on a DC negative terminal of the inverter and a threshold voltage that is a fixed value are compared, polarity thereof is changed at a predetermined rotor phase. The magnitude relation, for example, is detected by an inexpensive and simple apparatus such as a level shift circuit and a NOT circuit. The rotor phase of the permanent magnet synchronous motor is inferred on the basis of changes in the magnitude relation and if it is differentiated, a rotation speed is inferred. If the inferred values of the rotor phase and rotation speed are fed back to synchronous operation or vector control, the free-running permanent magnet synchronous motor is restarted.Type: ApplicationFiled: June 30, 2010Publication date: January 13, 2011Applicant: Hitachi, Ltd.Inventors: Satoshi SUMITA, Kazuaki Tobari, Shigehisa Aoyagi, Daisuke Maeda
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Patent number: 7821223Abstract: In a system in which current is detected in an inexpensive manner or in a system in which a position detector is omitted, the present invention provides a high-efficiency vector controller for a permanent magnet motor that can minimize current at the same torque even when there is setting error (R?R*) in resistance. Even when a current value commanded for the d-axis is set to zero, a virtual inductance value calculated from a detected q-axis current value is used for output voltage value calculation and phase error estimation calculation; so even if there is setting error (R?R*) in resistance, current can be minimized at the same torque and thereby the present invention can provide a high-efficiency vector controller for a permanent magnet motor.Type: GrantFiled: June 28, 2007Date of Patent: October 26, 2010Assignees: Hitachi, Ltd., Hitachi Car Engineering Co., LtdInventors: Kazuaki Tobari, Tsunehiro Endo, Kiyoshi Sakamoto, Daisuke Maeda, Shigehisa Aoyagi
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Publication number: 20100231148Abstract: When output voltage V1 of an electric power converter reaches a prescribed voltage V1*ref, a difference between V1 and V1*ref is integrated to correct a commanded torque to ?o* (?*=?o*+??).Type: ApplicationFiled: February 18, 2010Publication date: September 16, 2010Applicant: Hitachi Car Engineering Co., Ltd.Inventors: Kazuaki TOBARI, Shigehisa Aoyagi, Kentaro Ol
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Publication number: 20090322262Abstract: A motor control system includes a power converter, a vector controller for controlling the power converter, an axial error estimating operation for estimating an axial error which is a deviation between the phase estimation value and phase value of the motor, and a rotational speed estimating computing unit 5 for performing control so as to equalize the estimation value to a command of the axial error, a motor constant identification computing unit. The motor constant identification computing unit identifies a motor constant with a q-axis voltage component and a rotational speed identified value or a rotational speed command to reflect the identified motor constant in the vector controller.Type: ApplicationFiled: June 24, 2009Publication date: December 31, 2009Applicant: Hitachi, Ltd.Inventors: Kazuaki Tobari, Shigehisa Aoyagi, Satoshi Sumita
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Publication number: 20090146592Abstract: In a calculation for estimating axis error in a permanent magnet motor, a d-axis commanded voltage value is added to the product of three signals, which are a q-axis detected current value or commanded current value, an inductance value, and an estimated speed value, and then the resulting value is divided by the product of a commanded speed value ?r* and induced voltage constant Ke* or an arctangent calculation is performed in the same way, instead of using a resistance setting.Type: ApplicationFiled: December 9, 2008Publication date: June 11, 2009Inventors: Kazuaki TOBARI, Shigehisa AOYAGI
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Publication number: 20090058331Abstract: 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: ApplicationFiled: August 18, 2008Publication date: March 5, 2009Inventors: Shigehisa Aoyagi, Yoshitaka Iwaji, Kazuaki Tobari, Kiyoshi Sakamoto, Donsheng Li
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Patent number: 7388341Abstract: A vector control system for a permanent magnet synchronous motor, using a current control equivalent output value, a frequency instruction value, a current detection value, an inference phase error value, and a motor constant, identifies a motor resistance equivalent or a resistance setting error equivalent. Next, the vector control unit, using the identified value, corrects a set value R* equivalent of a voltage instruction calculation unit and a n inference phase error calculation unit. Thereby, a vector control system for a permanent magnet synchronous motor can realize a robust control characteristic for changing of a resistance constant of a motor in a low rotation speed area under position sensor-less control. Further, a vector control system for a permanent magnet synchronous motor can be applied in common in a system performing inexpensive current detection.Type: GrantFiled: August 17, 2005Date of Patent: June 17, 2008Assignee: Hitachi, Ltd.Inventors: Kazuaki Tobari, Kiyoshi Sakamoto, Tsunehiro Endo, Yoshitaka Iwaji, Yukio Kawabata, Shigehisa Aoyagi
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Publication number: 20080048606Abstract: In a system in which current is detected in an inexpensive manner or in a system in which a position detector is omitted, the present invention provides a high-efficiency vector controller for a permanent magnet motor that can minimize current at the same torque even when there is setting error (R?R*) in resistance. Even when a current value commanded for the d-axis is set to zero, a virtual inductance value calculated from a detected q-axis current value is used for output voltage value calculation and phase error estimation calculation; so even if there is setting error (R?R*) in resistance, current can be minimized at the same torque and thereby the present invention can provide a high-efficiency vector controller for a permanent magnet motor.Type: ApplicationFiled: June 28, 2007Publication date: February 28, 2008Inventors: Kazuaki Tobari, Terutaka Endo, Kiyoshi Sakamoto, Daisuke Maeda, Shigehisa Aoyagi
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Patent number: 7332882Abstract: A voltage detector is connected to a connection terminal connected to one phase of an AC output of an inverter through a diode. A removable charge power supply is connected to said connection terminal and another connection terminal. A charge-power-supply connection judging circuit judges whether the charge power supply is or isn't connected, based on a charge power supply voltage detected by a voltage detector. A mode change control circuit outputs switch signal by the result of said judgment. By receiving this switch signal, the inverter controller switches the operation of the inverter between the Motor Drive mode or the Battery Charge mode. Thereby, a motor drive device detects a connecting status of an external charge power supply and steadily switches the operation of the inverter between the Motor Drive mode or the Battery Charge mode.Type: GrantFiled: July 27, 2006Date of Patent: February 19, 2008Assignee: Hitachi, Ltd.Inventors: Shigehisa Aoyagi, Tsunehiro Endo, Hidefumi Shirahama, Yoshiki Ito