Patents by Inventor Sanshiro Obara

Sanshiro Obara 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).

  • Patent number: 6072288
    Abstract: A control apparatus of an electric motor vehicle includes a device for operating an initial magnetic pole location based on three phase magnetic pole location signal pulses of a permanent magnet electric motor upon starting the electric motor vehicle, a device for operating a magnetic pole phase of the permanent magnet electric motor on the basis of the initial magnetic pole location, a rotation pulse of the permanent magnet electric motor, and a correction value which are operated with the rise and fall of the three phase magnetic pole location signal pulse after the starting, a device for determining a current to be supplied into the permanent magnet electric motor based on the magnetic pole phase and a torque reference value, and a device for correcting the magnetic pole phase when a predetermined one of the three phase magnetic pole location signal pulses rises or falls.
    Type: Grant
    Filed: February 24, 1998
    Date of Patent: June 6, 2000
    Assignee: Hitachi, Ltd.
    Inventors: Katsuyuki Izumisawa, Sanshiro Obara, Toshisada Mitsui
  • Patent number: 6008617
    Abstract: A motor control device for an AC motor driven by a power converter with a maximum output frequency more than 500 Hz has a digital arithmetic unit which performs current-feed back control of the AC motor up to a maximum output frequency of the power converter, and outputs an AC voltage command to the power converter. The digital arithmetic unit includes a voltage control signal calculating unit for calculating a vector sum of the d-axis current deviation from a first subtracting unit and the q-axis current deviation from a second subtracting unit based on the d-axis and q-axis phases from a phase calculating unit as well as for calculating a d-axis voltage control signal and a q-axis voltage control signal according to the calculated vector sum, and performs current integration control for the d-axis and q-axis using the calculated vector sum as an input value. The AC voltage command is calculated based on the d-axis voltage control signal and the q-axis voltage control signals.
    Type: Grant
    Filed: November 24, 1998
    Date of Patent: December 28, 1999
    Assignee: Hitachi, Ltd.
    Inventors: Satoru Kaneko, Ryoso Masaki, Sanshiro Obara, Yuusuke Takamoto
  • Patent number: 5994870
    Abstract: A power corresponding to an A/C voltage command id1* is applied in the d-axis direction of rotational coordinates of a stopped synchronous motor via a current control unit, a three-phase converting unit, and a power converter. Further, by using "an amplitude value of a current iq' in the q-axis direction of the rotational coordinates generated in response to the A/C voltage command id1*" which is fed back and detected via a current detector and a dq converting unit, a field pole position estimation value .theta. is converged. The field pole position is estimated by using the converged field pole position estimation value .theta. as a true value of the field pole position .theta. of the synchronous motor.
    Type: Grant
    Filed: February 13, 1998
    Date of Patent: November 30, 1999
    Assignee: Hitachi, Ltd.
    Inventors: Satoru Kaneko, Ryoso Masaki, Yuusuke Takamoto, Taizou Miyazaki, Sanshiro Obara
  • Patent number: 5994881
    Abstract: A control apparatus for a synchronous generator system has: a voltage instruction generator for generating voltage instructions (V.sub.u *, V.sub.v *, V.sub.w *) based on an output power reference (P*) of the synchronous generator, currents (I.sub.u, I.sub.v) flowing through the synchronous generator and position information (.theta..sub.0, .omega..sub.r) of magnetic poles of the synchronous generator; a zero crossing point detector for detecting a point that the voltage (V.sub.u) of the synchronous generator passes through zero volt.; and a magnetic pole position calculator for calculating the information (.theta..sub.0, .omega..sub.r) on the position of magnetic poles of the synchronous generator on the basis of the voltage instruction (V.sub.u *) and the power reference (P*) when the synchronous generator is under the generation mode, and on the basis of an output signal of the zero crossing point detector when the synchronous generator is under the stand-by mode.
    Type: Grant
    Filed: October 7, 1997
    Date of Patent: November 30, 1999
    Assignee: Hitachi, Ltd.
    Inventors: Taizou Miyazaki, Ryoso Masaki, Satoru Kaneko, Kazuyoshi Sasazawa, Sanshiro Obara, Nobunori Matsudaira
  • Patent number: 5920161
    Abstract: In a driving system comprising a permanent magnet type synchronous machine, an electric power converter for the synchronous machine and a driving controller for driving the electric power converter, the driving controller comprises a current command generator for generating a d-axis current command and a q-axis current command of the synchronous machine, a d, q-axis current control uni for generating AC voltage command values Vu*, Vv* and Vw* based on the d-, q-axis currents from the synchronous machines, and a PWM control unit for generating driving signals for the electric power converter based on the AC voltage command values. A phase generator generates a phase signal from zero-cross point information of the AC voltage command values and a phase difference angle .delta. between induced voltage and terminal voltage of the synchronous machine; and a magnet temperature compensating unit generates a phase signal from zero-cross point information of the AC voltage command values and a phase difference angle .
    Type: Grant
    Filed: May 26, 1998
    Date of Patent: July 6, 1999
    Assignee: Hitachi, Ltd.
    Inventors: Sanshiro Obara, Kazuyoshi Sasazawa, Nobunori Matsudaira
  • Patent number: 5914582
    Abstract: A permanent magnet synchronous motor controller includes an inverter for supplying an alternating current power converted from a direct current power to a three-phase permanent magnet synchronous motor, having a pair of switching elements for each of said three phases of the motor; a smoothing capacitor for smoothing the direct current power connected to the inverter in parallel; and a control unit for controlling the motor by ON-OFF controlling each of the switching elements of the inverter, which further including a short circuit transition processing portion for changing control to 3-phase short circuit after performing precursory ON-OFF control of each of the switching elements so as to avoid occurrence of over current at an initial period of performing the 3-phase short circuit while the motor is being rotated.
    Type: Grant
    Filed: January 23, 1998
    Date of Patent: June 22, 1999
    Assignee: Hitachi, Ltd.
    Inventors: Yuusuke Takamoto, Ryoso Masaki, Hiroshi Katada, Sanshiro Obara
  • Patent number: 5877601
    Abstract: In an electric vehicle having a synchronous motor as the driving source, a control system and a control method for the electric vehicle can prevent over current in the main circuit or over charging of the battery at the re-closing of an opened inverter relay and is always capable of operating the power-train system in a better condition. A control method for an electric vehicle having an inverter for supplying a direct current electric power from a battery to the synchronous motor, a smoothing capacitor, connected to the inverter in parallel for smoothing the direct current electric power, an inverter control circuit and an inverter relay for connecting and disconnecting the inverter and the smoothing capacitor to and from the battery. The inverter is controlled so as to prevent current from flowing into or flowing out of the inverter until the re-closing operation of the inverter relay is completed when the opened inverter relay is re-closed.
    Type: Grant
    Filed: April 25, 1997
    Date of Patent: March 2, 1999
    Assignee: Hitachi, Ltd.
    Inventors: Sanshiro Obara, Hiroshi Katada, Nobunori Matsudaira, Eiichi Ohtsu, Ryoso Masaki
  • Patent number: 5877607
    Abstract: In a controller for an electric vehicle, a voltage current phase difference calculating circuit calculates a vector phase .theta..sub.c from a voltage command value and the primary current of an alternating current motor. The vector phase .theta..sub.c is input to a second voltage command circuit which calculates a second d-axis voltage command value and a second q-axis voltage command value using the vector phase .theta..sub.c and d-axis and q-axis current differences. By correcting the voltage command value using the second d-axis and second q-axis voltage command values, the stability of the current control system is improved. By controlling the electric vehicle using such a system, a stable current control can be attained even when the electric vehicle is driven under a regenerative running state or a weak magnetic field control state.
    Type: Grant
    Filed: August 30, 1996
    Date of Patent: March 2, 1999
    Assignee: Hitachi, Ltd.
    Inventors: Ryoso Masaki, Yuusuke Takamoto, Taizou Miyazaki, Satoru Kaneko, Sanshiro Obara
  • Patent number: 5841263
    Abstract: In a method and apparatus for motor control in an electric vehicle, current feedback control from an AC motor is performed using a digital arithmetic unit. The motor control equipment includes a power converter having a maximum output frequency of at least 500 Hz for driving the AC motor, and the digital arithmetic unit outputs an AC voltage command to the power converter based on current feedback from the AC motor up to the maximum output frequency of the power converter. The digital arithmetic unit includes a first subtractor for calculating the deviation between a detected value and a command value for the d-axis current, and a second subtractor for calculating the deviation between a detected value and a command value for the q-axis current. A phase calculator calculates a d-axis phase corresponding to the resistance and reactance components of the impedance of the d-axis, and a q-axis phase corresponding to the resistance components of the impedance of the q-axis.
    Type: Grant
    Filed: May 20, 1997
    Date of Patent: November 24, 1998
    Assignee: Hitachi, Ltd.
    Inventors: Satoru Kaneko, Ryoso Masaki, Sanshiro Obara, Yuusuke Takamoto
  • Patent number: 5726890
    Abstract: An electric vehicle control unit capable of position control so that the vehicle can be held in its stop position without vibration, even if an operator does not keep the brake pressed. The control circuit of the electric vehicle comprises a speed/torque instruction generation circuit, a position control selection circuit, a position instruction generation circuit and a motor control circuit. When the vehicle stops, control of the motor is changed from speed or torque control to position control.
    Type: Grant
    Filed: September 6, 1995
    Date of Patent: March 10, 1998
    Assignee: Hitachi, Ltd.
    Inventors: Yuusuke Takamoto, Ryoso Masaki, Sanshiro Obara, Satoru Kaneko
  • Patent number: 5677604
    Abstract: This invention aims to realize a superior control system for electric automobile, wherein the current can be accurately controlled according to the state of the automobile and yet high driving performance and charging performance can be achieved. When in the drive mode of the automobile, the system detects the current for drive using the current detector, controls the current of the inverter, and drives the induction motor. When in the charge mode, the system detects the current for charge using the current detector, controls the inverter, and charges the battery with the current from an external power supply. The intensity of the current differs by several times when driving and when charging, but the current detection range of the current detector for drive is wider than the current detection range of the current detector for charge. Therefore, the system detects higher current very accurately when driving and detects lower current very accurately when charging.
    Type: Grant
    Filed: April 8, 1994
    Date of Patent: October 14, 1997
    Assignee: Hitachi, Ltd.
    Inventors: Ryoso Masaki, Nobuyoshi Mutoh, Satoru Kaneko, Sanshiro Obara
  • Patent number: 5661380
    Abstract: The present invention provides a protection apparatus in a control system for an electric vehicle which is capable of performing back-up driving by using a back-up control method, without using output from sensors even if the sensor in the control system for ordinary driving is failed. When at least one of the current sensor, the speed sensor and the accelerator sensor is detected to be abnormal, a back-up control voltage v1 is output as an abnormal signal from a running back-up control circuit. As a result, the running back-up control circuit sets the limiter of the output of the current control circuit to zero and switches the control signal to the inverter from vector control to V/f voltage control.
    Type: Grant
    Filed: November 7, 1995
    Date of Patent: August 26, 1997
    Assignees: Hitachi, Ltd., Hitachi Car Engineering Co., Ltd.
    Inventors: Sanshiro Obara, Shigeyuki Yoshihara, Hiroyuki Yamada, Nobunori Matsudaira
  • Patent number: 5659235
    Abstract: In an electric vehicle drive controller, a drive controller has a controlling means which incorporates means for calculating a magnetic flux command from a basic torque command, for calculating a torque current command, exciting current command and slip frequency, and for operating vector calculation, and drives the motor. Voltage or power density of the power source is input to a correction coefficient calculating means and then input to a magnetic flux generating means by a correction coefficient to correct a magnetic flux. A magnetic flux generating means calculates the magnetic flux command by limiting and correcting the magnetic flux command according to the basic torque command and rotating speed, and determines a control variable for the magnetic flux command in correspondence to the motor rotating speed and torque command.
    Type: Grant
    Filed: February 22, 1996
    Date of Patent: August 19, 1997
    Assignees: Hitachi, Ltd., Hitachi Car Engineering Co., Ltd.
    Inventors: Hiroyuki Yamada, Nobunori Matsudaira, Sanshiro Obara
  • Patent number: 5650700
    Abstract: An electric vehicle torque controller has a torque calculating unit and an actual torque detecting unit. The calculated torque is compared with the actual torque to generate a torque compensation value, which is converted to a torque current signal. The torque current signal is used to generate a slip frequency, which is added to an output of an angular speed detector and used to set a secondary magnetic flux value. A secondary magnetic flux signal is generated according to the secondary magnetic flux value and the torque current signal. A secondary magnetic flux estimating unit generates an estimated secondary magnetic flux value, which is used to determine the exciting current. Primary motor current is controlled in response to the exciting current, the torque current, motor speed and slip value.
    Type: Grant
    Filed: April 20, 1995
    Date of Patent: July 22, 1997
    Assignee: Hitachi, Ltd.
    Inventors: Nobuyoshi Mutoh, Taizou Miyazaki, Ryoso Masaki, Tsutomu Ohmae, Sanshiro Obara
  • Patent number: 5631819
    Abstract: The invention provides an electric power converter system which uses a standard low-priced control processor and is suitable for improving the voltage utilization factor in the output voltage. D-axis and q-axis voltage commands and a rotation angle .theta. defining a voltage command vector on a rotating coordinate system are input to a voltage calculation circuit. The voltage command vector is transformed in a rotating coordinate transformation unit into a .alpha. axis and .beta. axis voltage commands to be defined relative to stationary coordinate system. A judgment unit determines which section contains the voltage command vector, from among three sections on the stationary coordinate system having one axis thereof (.alpha.-axis for example) coinciding with one axis of the three phases. A three phase voltage generation unit then selects a method of calculation on the basis of a result of the section determination, and calculates three phase voltage command values respectively utilizing the .alpha.
    Type: Grant
    Filed: April 16, 1996
    Date of Patent: May 20, 1997
    Assignee: Hitachi, Ltd.
    Inventors: Ryoso Masaki, Takashi Ikimi, Hironori Ohashi, Yuusuke Takamoto, Seiji Ishida, Sanshiro Obara
  • Patent number: 5631796
    Abstract: An electric vehicle control system which maintains good driving performance under normal conditions, and can cut off driving current upon malfunction of a microcomputer before restarting. A setting circuit of a comparing and operating circuit has a set signal fixed to V2 if an accelerator pedal is released. If a microcomputer malfunctions to drive an inverter absent a depression of the accelerator pedal, a current flows from a battery and a battery current sensor generates an output signal n. If this value exceeds V2, a comparator is turned on, which also turns on a transistor to energize a relay and disconnects an inverter drive signal s to break the power supply from an inverter to the ac motor. Upon disconnection, an alarm lamp is lit to issue an alarm to the driver. The disconnection is held by a delay circuit until the power is reset.
    Type: Grant
    Filed: November 3, 1995
    Date of Patent: May 20, 1997
    Assignees: Hitachi, Ltd., Hitachi Automotive Engineering Co. Ltd.
    Inventors: Shigeyuki Yoshihara, Sanshiro Obara, Nobunori Matsudaira, Shotaro Naito
  • Patent number: 5610483
    Abstract: A control equipment for controlling a current to the motor provided in an electric vehicle is disclosed. The control equipment has a motor torque control means for inputting the motor speed No and the motor current, and generating an inverter drive signal to control the torque of the motor, a notch filter for eliminating the mechanical resonance frequency; and a torque command generating means for generating the torque command.The control equipment for an electric vehicle is not influenced by the mechanical vibration of the electric vehicle, can generate the accurate motor torque command, and can execute the stable running control.
    Type: Grant
    Filed: March 17, 1995
    Date of Patent: March 11, 1997
    Assignees: Hitachi Ltd., Hitachi Automotive Engineering Co., Ltd.
    Inventors: Sanshiro Obara, Hiroyuki Yamada, Nobunori Matsudaira, Ryoso Masaki
  • Patent number: 5600215
    Abstract: The invention provides an electric vehicle controller in which the generated motor torque is limited when the voltage of the vehicle battery decreases during running, in order to suppress over-discharge of the battery. A high torque can be obtained for a short period, however, even in the torque limiting period, and over-discharge is prevented by stopping electric power converting means in a final stage of discharge voltage of the battery. According to the invention, during operation of the vehicle, the battery terminal voltage is monitored and compared with a first comparison value V.sub.1. If the battery voltage falls below V.sub.1, a first counter commences measurement of the time period during which this condition continues. If the time period measured by the first counter reaches a preset value t.sub.1, torque limitation is initiated.
    Type: Grant
    Filed: July 7, 1995
    Date of Patent: February 4, 1997
    Assignees: Hitachi, Ltd., Hitachi Automotive Engineering Co., Ltd.
    Inventors: Hiroyuki Yamada, Shotaro Naito, Sanshiro Obara
  • Patent number: 5557181
    Abstract: The invention provides a brake control apparatus for an electric motor vehicle that can control a charging current depending on a charging state of a dc power supply to avoid overcharging it. In regenerative braking, according to the invention, the charging state of a battery is detected by a charging state detector, which sends a detection signal to a control unit. When the state of charge of the battery exceeds a predetermined level, the control unit controls operating parameters of an inverter so that the charging current to the battery is decreased. If, however, insufficient torque results, the control unit turns on an electric load to increase the control torque. If further load absorption is needed, the control unit turns on electric braking means.
    Type: Grant
    Filed: September 20, 1993
    Date of Patent: September 17, 1996
    Assignee: Hitachi, Ltd.
    Inventors: Shotaro Naito, Sanshiro Obara, Nobuyoshi Mutoh
  • Patent number: 5534764
    Abstract: A vehicle control system for driving an electric vehicle having driving force generating means for driving the vehicle, accumulating means for accumulating driving energy for said vehicle, means for supplying the energy of said accumulating means to said driving force generating means, and control means for controlling said supplying means using a torque command generated by said driving force generating means. The control means includes a vehicle model simulating the operation of said vehicle under the torque generated by said driving force generating means and torque command calculating means for calculating said torque command using a value of vehicle model speed calculated by said vehicle model and the rotating speed of said driving force generating means.
    Type: Grant
    Filed: December 7, 1994
    Date of Patent: July 9, 1996
    Assignee: Hitachi, Ltd.
    Inventors: Ryoso Masaki, Nobuyoshi Mutoh, Sanshiro Obara