Patents by Inventor CaoMinh Ta
CaoMinh Ta 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: 8285451Abstract: Disclosed herein is a method for controlling an electric power steering system, wherein a motor is controlled by vector control and driven by a current command value calculated on the basis of a parameter such as a steering torque to provide a steering assist power to a vehicle steering system, and further wherein the current command value is limited on the basis of desired output characteristics and a desired angular speed during a field-weakening control and a non-field-weakening control of the vector control.Type: GrantFiled: March 17, 2006Date of Patent: October 9, 2012Assignee: NSK Ltd.Inventors: CaoMinh Ta, ChunHao Jiang, Hideyuki Kobayashi
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Publication number: 20090234538Abstract: Disclosed herein is a method for controlling an electric power steering system, wherein a motor is controlled by vector control and driven by a current command value calculated on the basis of a parameter such as a steering torque to provide a steering assist power to a vehicle steering system, and further wherein the current command value is limited on the basis of desired output characteristics and a desired angular speed during a field-weakening control and a non-field-weakening control of the vector control.Type: ApplicationFiled: March 17, 2006Publication date: September 17, 2009Applicant: NSK LTD.Inventors: CaoMinh Ta, ChunHao Jiang, Hideyuki Kobayashi
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Patent number: 7574294Abstract: A control apparatus of an electric power steering apparatus is provided in which a nonlinear element of a motor model of-the electric power steering apparatus is compensated beforehand to linearize the motor model and the back electromotive force of the motor is computed to compensate the back electromotive force for a control loop, and conduct back electromotive force compensation with no lag in order to realize a control apparatus of an electric power steering apparatus with less control error, stable controllability, small motor output torque ripple, good wheel steering feeling, and less motor noise.Type: GrantFiled: May 14, 2004Date of Patent: August 11, 2009Assignees: NSK Ltd., NSK Steering Systems Co., Ltd.Inventors: CaoMinh Ta, ChunHao Jiang, Shuji Endo
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Patent number: 7548035Abstract: The invention relates to a control apparatus of an electric power steering apparatus structured such as to apply a steering assist force generated by a n-phase motor to a steering system of a vehicle, the control apparatus is provided with at least (n?1) numbers of current detecting means for detecting a current Im in each of phases of the motor, a current command value calculating means for outputting a current command value Imref in each of the phases, and n numbers of current control means, and the control apparatus executes a current control of each of the phases by the current control means having the current command value Imref in each of the phases and the current Im in each of the phases as an input.Type: GrantFiled: November 24, 2004Date of Patent: June 16, 2009Assignees: NSK Ltd., NSK Steering Systems Co., Ltd.Inventors: Shuji Endo, Yuho Aoki, Hideyuki Kobayashi, CaoMinh Ta
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Patent number: 7499780Abstract: A control apparatus of an electric power steering apparatus is provided in which a nonlinear element of a motor model of-the electric power steering apparatus is compensated beforehand to linearize the motor model and the back electromotive force of the motor is computed to compensate the back electromotive force for a control loop, and conduct back electromotive force compensation with no lag in order to realize a control apparatus of an electric power steering apparatus with less control error, stable controllability, small motor output torque ripple, good wheel steering feeling, and less motor noise.Type: GrantFiled: May 14, 2004Date of Patent: March 3, 2009Assignees: NSK Ltd., NSK Steering Systems Co., Ltd.Inventors: CaoMinh Ta, ChunHao Jiang, Shuji Endo
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Patent number: 7463006Abstract: The invention provides a drive control device for the motor as well as an electric power steering apparatus using the motor and the drive control device. Respective phase current command values are calculated on the basis of vector control. Pseudo-vector control for controlling respective phases separately is used as current feedback control.Type: GrantFiled: September 25, 2007Date of Patent: December 9, 2008Assignee: NSK Ltd.Inventors: CaoMinh Ta, Shuji Endo
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Patent number: 7443131Abstract: A control device for electric power steering apparatus, in which when torque ripples at the time of the rotation of a motor is reduced by simple arithmetic, smooth and safe assist limitation is performed without deteriorating steering feeling, is provided. For this reason, in the control device for electric power steering apparatus adopting a vector control system for applying an assist force of a motor to a steering system, a phase delay according to an angular velocity is obtained, a corrected electric angle is calculated by adding the phase delay to an electric angle, and generation of a current command value in the vector control is compensated based on the corrected electric angle.Type: GrantFiled: December 12, 2004Date of Patent: October 28, 2008Assignees: NSK Ltd., NSK Steering Systems Co., Ltd.Inventors: CaoMinh Ta, Hideyuki Kobayashi, Shuji Endo
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Patent number: 7345442Abstract: Distortions of motor voltage and current and a torque ripple of the motor are generated by dead band compensation for preventing an arm short circuit of an inverter, and a feeling of physical disorder is given in a handle operation. Therefore, the distortions of the motor voltage and current and the torque ripple of the motor are improved by using the dead band compensation for estimating the voltage distortion on the basis of a model current generated from a current command value such that no feeling of physical disorder is given in the handle operation of an electric power steering apparatus.Type: GrantFiled: September 1, 2004Date of Patent: March 18, 2008Assignees: NSK Ltd., NSK Steering Systems Co., Ltd.Inventors: CaoMinh Ta, Hiroaki Takase, Hideyuki Kobayashi
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Patent number: 7339346Abstract: The invention provides a motor for a brushless DC motor, which has small torque ripple even if a trapezoidal wave current is supplied and has a small size and reduced motor noise, and a drive control device for the motor as well as an electric power steering apparatus using the motor and the drive control device. Respective phase current command values are calculated on the basis of vector control. Pseudo-vector control for controlling respective phases separately is used as current feedback control.Type: GrantFiled: November 27, 2003Date of Patent: March 4, 2008Assignee: NSK Ltd.Inventors: CaoMinh Ta, Shuji Endo
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Publication number: 20080018278Abstract: The invention provides a motor for a brushless DC motor, which has small torque ripple even if a trapezoidal wave current is supplied and has a small size and reduced motor noise. Respective phase current command values are calculated on the basis of vector control. Pseudo-vector control for controlling respective phases separately is used as current feedback control.Type: ApplicationFiled: September 25, 2007Publication date: January 24, 2008Applicant: NSK Ltd.Inventors: CaoMinh TA, Shuji Endo
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Publication number: 20080018277Abstract: The invention provides a drive control device for the motor as well as an electric power steering apparatus using the motor and the drive control device. Respective phase current command values are calculated on the basis of vector control. Pseudo-vector control for controlling respective phases separately is used as current feedback control.Type: ApplicationFiled: September 25, 2007Publication date: January 24, 2008Applicant: NSK Ltd.Inventors: CaoMinh TA, Shuji Endo
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Publication number: 20070158132Abstract: A control device for electric power steering apparatus, in which when torque ripples at the time of the rotation of a motor is reduced by simple arithmetic, smooth and safe assist limitation is performed without deteriorating steering feeling, is provided. For this reason, in the control device for electric power steering apparatus adopting a vector control system for applying an assist force of a motor to a steering system, a phase delay according to an angular velocity is obtained, a corrected electric angle is calculated by adding the phase delay to an electric angle, and generation of a current command value in the vector control is compensated based on the corrected electric angle.Type: ApplicationFiled: December 12, 2004Publication date: July 12, 2007Inventors: CaoMinh Ta, Hideyuki Kobayashi, Shuji Endo
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Publication number: 20070090782Abstract: The invention relates to a control apparatus of an electric power steering apparatus structured such as to apply a steering assist force generated by a n-phase motor to a steering system of a vehicle, the control apparatus is provided with at least (n?1) numbers of current detecting means for detecting a current Im in each of phases of the motor, a current command value calculating means for outputting a current command value Imref in each of the phases, and n numbers of current control means, and the control apparatus executes a current control of each of the phases by the current control means having the current command value Imref in each of the phases and the current Im in each of the phases as an input.Type: ApplicationFiled: November 24, 2004Publication date: April 26, 2007Inventors: Shuji Endo, Yuho Aoki, Hideyuki Kobayashi, CaoMinh Ta
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Patent number: 7187154Abstract: The present invention provides a motor drive apparatus capable of calculating an angular velocity and a rotation angle accurately in the entire rotation velocity range of a motor using a cheap Hall sensor having an inferior accuracy without using an expensive resolver having a high accuracy. The present invention includes a first angular velocity calculating means for calculating the angular velocity based on the back-EMF of the motor when it rotates at low speeds and a second angular velocity calculating means for calculating the angular velocity based on a signal from the Hall sensor when it rotates at high speeds. According to the present invention, the angular velocity and rotation angle can be calculated accurately in the entire rotation speed range using the Hall sensor under hybrid usage.Type: GrantFiled: April 27, 2005Date of Patent: March 6, 2007Assignees: NSK Ltd., NSK Steering Systems Co., Ltd.Inventors: CaoMinh Ta, Shuji Endo, Hideyuki Kobayashi, Masahide Saito
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Publication number: 20070029959Abstract: Distortions of motor voltage and current and a torque ripple of the motor are generated by dead band compensation for preventing an arm short circuit of an inverter, and a feeling of physical disorder is given in a handle operation. Therefore, the distortions of the motor voltage and current and the torque ripple of the motor are improved by using the dead band compensation for estimating the voltage distortion on the basis of a model current generated from a current command value such that no feeling of physical disorder is given in the handle operation of an electric power steering apparatus.Type: ApplicationFiled: September 1, 2004Publication date: February 8, 2007Inventors: CaoMinh Ta, Hiroaki Takase, Hideyuki Kobayashi
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Publication number: 20070007072Abstract: A control apparatus of an electric power steering apparatus is provided in which a nonlinear element of a motor model of-the electric power steering apparatus is compensated beforehand to linearize the motor model and the back electromotive force of the motor is computed to compensate the back electromotive force for a control loop, and conduct back electromotive force compensation with no lag in order to realize a control apparatus of an electric power steering apparatus with less control error, stable controllability, small motor output torque ripple, good wheel steering feeling, and less motor noise.Type: ApplicationFiled: May 14, 2004Publication date: January 11, 2007Inventors: CaoMinh Ta, ChunHao Jiang, Shuji Endo
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Publication number: 20060176005Abstract: In order to precisely control rotation of a motor, it is necessary to precisely detect a position of a rotor. Even if an inexpensive position detecting sensor having relatively low precision such as a Hall sensor is used, it is possible to provide a motor drive control apparatus capable of precisely detecting the position of the rotor by calculating an electrical angle of the rotor (rotor position) by calculating a back-EMF from a detected voltage, detected motor current, a motor winding resistance value and an inductance value, and by periodically correcting a calculation error of the calculated electrical angle. If such a motor drive control apparatus is used, it is possible to provide an inexpensive electric power steering apparatus having excellent steering feeling.Type: ApplicationFiled: April 1, 2004Publication date: August 10, 2006Inventors: CaoMinh Ta, ChunHao Jiang, Hideyuki Kobayashi
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Publication number: 20060145652Abstract: The present invention provides a motor drive apparatus and an electric power steering apparatus using the same, in which the motor can be vector controlled even if a motor position detection sensor such as a hole sensor which cannot output a precise and detailed rotation angle signal when the motor rotates at low speed, field weakening control can reliably be carried out even if there exists detection error of a motor position detection sensor or the like, and motor output having small torque ripple can be expected.Type: ApplicationFiled: December 11, 2003Publication date: July 6, 2006Inventors: CaoMinh Ta, ChunHao Jiang, Shuji Endo
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Publication number: 20060071628Abstract: The invention provides a motor for a brushless DC motor, which has small torque ripple even if a trapezoidal wave current is supplied and has a small size and reduced motor noise, and a drive control device for the motor as well as an electric power steering device using the motor and the drive control device. Respective phase current command values are calculated on the basis of vector control. Pseudo-vector control for controlling respective phases separately is used as current feedback control.Type: ApplicationFiled: November 27, 2003Publication date: April 6, 2006Inventors: CaoMinh Ta, Shuji Endo
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Publication number: 20050242765Abstract: The present invention provides a motor drive apparatus capable of calculating an angular velocity and a rotation angle accurately in the entire rotation velocity range of a motor using a cheap Hall sensor having an inferior accuracy without using an expensive resolver having a high accuracy. The present invention includes a first angular velocity calculating means for calculating the angular velocity based on the back-EMF of the motor when it rotates at low speeds and a second angular velocity calculating means for calculating the angular velocity based on a signal from the Hall sensor when it rotates at high speeds. According to the present invention, the angular velocity and rotation angle can be calculated accurately in the entire rotation speed range using the Hall sensor under hybrid usage.Type: ApplicationFiled: April 27, 2005Publication date: November 3, 2005Inventors: CaoMinh Ta, Shuji Endo, Hideyuki Kobayashi, Masahide Saito