Electric power steering apparatus

Patent metadata

Field	Value
Publication number	US-2018354549-A1
Application number	US-201715552323-A
Country	US
Kind code	A1
Filing date	Feb 10, 2017
Priority date	Feb 24, 2016
Publication date	Dec 13, 2018
Grant date	—

Abstract

An electric power steering apparatus that can suppress deterioration of steering feeling by changing a current command value of a normal system in motor control by two systems when an abnormality occurs in any of the systems. The steering apparatus calculates a current command value to a motor having two-system motor windings for each system, comprises a current command value adjusting section that calculates the current command value by using a steering assist command value and a compensation current command value.

First claim

1 - 6 . (canceled)

7 . An electric power steering apparatus that assists and controls a steering system by calculating a current command value to a motor having two-system motor windings for each system and driving said motor based on said current command value, comprising:
a current command value adjusting section that calculates said current command value by using a steering assist command value and a compensation current command value; wherein said current command value adjusting section has a normal-time coefficient used at normal time and an abnormal-time coefficient used at abnormal time that are set to each system, a value obtained by multiplying a value obtained by adding said steering assist command value and said compensation current command value by said normal-time coefficient is said current command value when said two systems are normal, and a value obtained by adding said compensation current command value to a value obtained by multiplying said steering assist command value by said abnormal-time coefficient is said current command value to a normal system of said systems when an abnormality occurs in any of said systems.

8 . The electric power steering apparatus according to claim 7 ,
wherein said electric power steering apparatus further comprises: a steering assist command value calculating section that calculates said steering assist command value; a compensation current command value calculating section that calculates said compensation current command value; and an abnormality detecting section that detects said abnormality and outputs a signal that informs a system where said abnormality occurs when said abnormality occurs in any of said systems; and wherein said current command value adjusting section calculates said current command value based on presence of said signal and content of said signal by using said steering assist command value calculated in said steering assist command value calculating section and said compensation current command value calculated in said compensation current command value calculating section.

9 . The electric power steering apparatus according to claim 7 ,
wherein said normal-time coefficient is more than or equal to 0.3 and less than or equal to 0.7, and said abnormal-time coefficient is more than or equal to 0.3 and less than or equal to 0.7.

10 . The electric power steering apparatus according to claim 8 ,
wherein said normal-time coefficient is more than or equal to 0.3 and less than or equal to 0.7, and said abnormal-time coefficient is more than or equal to 0.3 and less than or equal to 0.7.

11 . An electric power steering apparatus that assists and controls a steering system by calculating a current command value to a motor having two-system motor windings for each system and driving said motor based on said current command value, comprising:
a current command value adjusting section that calculates said current command value by using a steering assist command value and a compensation current command value; wherein said current command value adjusting section has a normal-time coefficient used at normal time and a first abnormal-time coefficient and a second abnormal-time coefficient used at abnormal time that are set to each system, a value obtained by multiplying a value obtained by adding said steering assist command value and said compensation current command value by said normal-time coefficient is said current command value when said two systems are normal, and a value obtained by adding a value obtained by multiplying said steering assist command value by said first abnormal-time coefficient and a value obtained by multiplying said compensation current command value by said second abnormal-time coefficient is said current command value to a normal system of said systems when an abnormality occurs in any of said systems.

12 . The electric power steering apparatus according to claim 11 ,
wherein said electric power steering apparatus further comprises: a steering assist command value calculating section that calculates said steering assist command value; a compensation current command value calculating section that calculates said compensation current command value; and an abnormality detecting section that detects said abnormality and outputs a signal that informs a system where said abnormality occurs when said abnormality occurs in any of said systems; and wherein said current command value adjusting section calculates said current command value based on presence of said signal and content of said signal by using said steering assist command value calculated in said steering assist command value calculating section and said compensation current command value calculated in said compensation current command value calculating section.

13 . The electric power steering apparatus according to claim 11 ,
wherein said normal-time coefficient is more than or equal to 0.3 and less than or equal to 0.7, said first abnormal-time coefficient is more than or equal to 0.3 and less than or equal to 0.7, and said second abnormal-time coefficient is more than or equal to 0.7 and less than or equal to 1.2.

14 . The electric power steering apparatus according to claim 12 ,
wherein said normal-time coefficient is more than or equal to 0.3 and less than or equal to 0.7, said first abnormal-time coefficient is more than or equal to 0.3 and less than or equal to 0.7, and said second abnormal-time coefficient is more than or equal to 0.7 and less than or equal to 1.2.

Assignees

• Nsk Ltd

Inventors

• Tsubaki Takahiro

Classifications

• B62D5/0463 Primary

  calculating assisting torque from the motor based on driver input · CPC title

• B62D5/0481

  monitoring the steering system, e.g. failures · CPC title

• H02P29/028

  the motor continuing operation despite the fault condition, e.g. eliminating, compensating for or remedying the fault · CPC title

• H02P29/0241

  the fault being an overvoltage · CPC title

• H02P29/032

  Preventing damage to the motor, e.g. setting individual current limits for different drive conditions · CPC title