Patents by Inventor Yasutami Kito

Yasutami Kito 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: 5241255
    Abstract: A control system for an electric motor includes a detector associated with a regenerated power absorbing circuit for monitoring operation of the regenerated power absorbing circuit for detecting an abnormal condition thereof. The control circuit is responsive to detection of abnormality in the regenerated power absorbing circuit for controlling operation of an inverter in a fail-safe mode.
    Type: Grant
    Filed: October 24, 1988
    Date of Patent: August 31, 1993
    Assignee: Otis Elevator Company
    Inventors: Kenji Oshima, Yasutami Kito
  • Patent number: 5130617
    Abstract: An inverter control device for controlling an induction motor that drives elevators, has two induction motor coils that are electrically separate with inverters connected to each coil, and a control device that controls these two inverters with the same current command. The preferred structure is one where one control system outputs one current command to two inverters, the inverter control device has two separate control systems that divide one current command and output each half to the respective inverter and one carrier circuit that modulates each control system at the same timing, or two separate converters are connected to the power element of the respective inverters.
    Type: Grant
    Filed: January 2, 1991
    Date of Patent: July 14, 1992
    Assignee: Otis Elevator Company
    Inventors: Kenji Oshima, Yasutami Kito
  • Patent number: 5070426
    Abstract: A clipper circuit includes an auxiliary diode connected between a capacitor and diode, themselves forming a clipper circuit. The auxiliary diode thus forms an auxiliary clipper circuit taking the capacitor as a common capacitor. The clipper circuit diodes shunt current from the capacitor into first and second currents through the diodes. This obviates the necessity for a snubber circuit and power source clipper circuit as employed in the prior art.
    Type: Grant
    Filed: February 28, 1990
    Date of Patent: December 3, 1991
    Assignee: Otis Elevator Company
    Inventors: Masao Iwasa, Yasutami Kito
  • Patent number: 4995478
    Abstract: An elevator starting compensation device for performing starting compensation with addition of a load detection signal and a torque command signal comprising a speed command circuit, an automatic speed regulator amplifier for outputting the torque command signal, and a load detecting element for detecting load of a passenger cage, characterized in that it further includes a static frictional torque compensating element inputting a load detection signal and travel (lifting and lowering) signal and outputting a static frictional torque compensation signal predetermined according to the magnitude of the sensed passenger load, the torque compensation signal being added to the torque command signal so that start-up of actual speed is not delayed with respect to the speed command.
    Type: Grant
    Filed: April 20, 1989
    Date of Patent: February 26, 1991
    Assignee: Otis Elevator Company
    Inventors: Kenji Oshima, Yasutami Kito
  • Patent number: 4994951
    Abstract: The present invention is achieved with a control unit for a PWM inverter for comparing (8) a voltage command signal (7) with the fundamental of the inverter's output voltage waveform and for comparing (11) the result with a carrier signal (10) and using that result to keep the output voltage waveform equal to the voltage command signal. The use of the output's fundamental for feedback eliminates the prior art need to use slight delays in the inverter's switching stage thereby removing the prior art torque ripple and consequent vibration problems particularly at low speed and furthermore enables smoother stopping and starting control using variable speed ranges of several hundred to one.
    Type: Grant
    Filed: April 20, 1989
    Date of Patent: February 19, 1991
    Assignee: Otis Elevator Company
    Inventors: Masao Iwasa, Yasutami Kito
  • Patent number: 4987320
    Abstract: A multiphase multiplier circuit employs analog switches, each of which is duty controlled for multiplying input voltage signal with a multiplier determined depending on the duty cycle ON/OFF period. The multiphase multiplier circuit further includes means for multiplying a reference voltage signal by a desired factor for deriving the difference between the product and the factor for controlling duty cycles of the analog switches.
    Type: Grant
    Filed: May 22, 1989
    Date of Patent: January 22, 1991
    Assignee: Otis Elevator Company
    Inventors: Kenji Oshima, Yasutami Kito
  • Patent number: 4982816
    Abstract: In an elevator provided with an inverter driven induction motor, output torque is determined by direct current of an inverter, slip frequency is determined from the thusly determined torque, the gap between an open-loop dictated speed pattern and the actual speed is compensated by the slip calculated during acceleration and constant speed movement, so that the open-loop control may be improved in terms of stop position precision.
    Type: Grant
    Filed: April 18, 1989
    Date of Patent: January 8, 1991
    Assignee: Otis Elevator Company
    Inventors: Kazuhiko Doi, Yasutami Kito
  • Patent number: 4903187
    Abstract: A star-connected sensing resistor at the A.C. output side of a PWM inverter detects an output voltage across the resistor, a PWM control according to the invention then amplifies the detected voltage, compares the amplified voltage with a sine wave voltage command signal, amplifies the compared output in a P-I amplifier having a definite gain for a D.C. current, compares the P-I amplified output to a carrier and thus provides a PWM output for controlling the inverter.
    Type: Grant
    Filed: April 18, 1989
    Date of Patent: February 20, 1990
    Assignee: Otis Elevator Company
    Inventors: Kazuhiko Doi, Yasutami Kito
  • Patent number: 4902954
    Abstract: An apparatus for controlling an adjustable-speed alternating current motor coupled to drive an elevator cage. The apparatus includes a converter connected to a source of AC power for converting the AC power into DC power, an inverter connected through relatively positive and negative conductors to the converter for inverting the DC power into DC output power having adjustable frequency, voltage magnitude, and current magnitude to drive the motor, and a control circuit for controlling an inverter to drive the motor at an adjustable speed. When a power failure occurs, the control circuit prevents flow of power through the converter to the power source and reduces the current magnitude of the inverter output power to a predetermined minimum limit enough to maintain a synchronous relationship between the inverter and the motor.
    Type: Grant
    Filed: June 6, 1988
    Date of Patent: February 20, 1990
    Inventors: Kenji Oshima, Yasutami Kito
  • Patent number: 4870334
    Abstract: An apparatus for controlling an adjustable-speed electric motor. The actual motor speed is sensed and compared with a commanded motor speed. A speed error signal, which depends on the difference between the actual and desired values of motor speed, is derived and applied to a proportional-plus-integral control circuit which converts it into a first torque command signal. The speed command signal is converted into a second torque command signal proportional to the rate of change of the speed command signal. The second torque command signal is added to the first torque command signal to provide a torque command signal. A control circuit responds to the torque command signal by controlling the operation of the motor in accordance with the torque command signal.
    Type: Grant
    Filed: June 6, 1988
    Date of Patent: September 26, 1989
    Assignee: Otis Elevator Company
    Inventors: Masao Iwasa, Yasutami Kito, Masayuki Mori
  • Patent number: 4734634
    Abstract: When an inverter is disconnected from a rotating motor due to power failure or motor accident, it is necessary to connect the inverter power again to the rotating motor by the inertia force in order to keep the motor rotating. To achieve the above reconnection, the inverter is controlled in accordance with open-loop control method, without use of any motor speed detecting means, thus improving control response speed. In reconnection, the inverter is started at a frequency higher than the rotating motor speed and at a voltage lower than the rated value; when a predetermined time has elapsed after the starting voltage was applied to the motor, only the frequency is decreased; when inverter driving current drops below a predetermined value, the frequency is held and only the voltage is increased until the voltage-to-frequency ratio reaches a predetermined value.
    Type: Grant
    Filed: November 28, 1986
    Date of Patent: March 29, 1988
    Assignee: Kabushiki Kaisha Meidensha
    Inventors: Yasutami Kito, Kuniake Yasukawa
  • Patent number: 4607205
    Abstract: When an inverter is disconnected from a rotating motor due to power failure or motor accident, it is necessary to connect the inverter power again to the motor rotating by the inertia force in order to keep the motor rotating. To achieve the above reconnection, the inverter is controlled in accordance with the open-loop control method, without use of any motor speed detecting means, thus improving control response speed. In reconnection, the inverter is started at a frequency higher than the rotating motor speed and at a voltage lower than the rated value; only the frequency is decreased gradually but increased gradually again when the detected motor driving current reaches zero or the motor regenerated current starts flowing; and the voltage is raised when the detected motor regenerated current reaches its maximum value.
    Type: Grant
    Filed: October 16, 1984
    Date of Patent: August 19, 1986
    Assignee: Kabushiki Kaisha Meidensha
    Inventors: Yasutami Kito, Kuniake Yasukawa