Electric power steering apparatus
First Claim
1. An electric power steering apparatus for a vehicle, comprising:
- a steering torque sensor for detecting a steering torque of a steering system of the vehicle and generating a steering torque signal corresponding to the detected steering torque;
an electric motor for applying a steering assist force to the steering system;
a motor current sensor for detecting a motor current flowing in said electric motor and generating a motor current signal corresponding to the detected motor current; and
a control unit for controlling operation of said electric motor on the basis of at least the steering torque, said control unit includinga target current setting section for setting, on the basis of said steering torque signal, a target current to be supplied to said electric motor and generating a target current signal corresponding to the target current,a proportional plus integral control section for achieving proportional plus integral control action about an offset between said target current signal and said motor current signal so as to effect compensation of said offset, andan overshoot diminishing section operatively connected to said proportional plus integral control section for controlling at least one of a proportional sensitivity and an integral gain of said proportional plus integral control section so as to diminish overshoot occurring in the motor current, wherein said overshoot diminishing section changes said proportional sensitivity and/or said integral gain of said proportional plus integral control section on the basis of said motor current signal supplied from said motor current sensor.
1 Assignment
0 Petitions
Accused Products
Abstract
An electric power steering apparatus includes a proportional plus integral control section incorporated in a control unit for achieving proportional plus integral control action of an offset between a target motor current to be supplied to an electric motor and a motor current actually flowing in the electric motor, and an overshoot diminishing section for controlling at least one of proportional sensitivity and integral gain of the proportional plus integral control section so as to diminish overshoot of the motor current occurring when the steering wheel is quickly turned until it reaches a steering lock position. With this arrangement, semiconductor devices used in the control unit for driving the electric motor are protected against damage caused when subjected to an overload resulting from the overshoot of the motor current.
49 Citations
10 Claims
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1. An electric power steering apparatus for a vehicle, comprising:
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a steering torque sensor for detecting a steering torque of a steering system of the vehicle and generating a steering torque signal corresponding to the detected steering torque; an electric motor for applying a steering assist force to the steering system; a motor current sensor for detecting a motor current flowing in said electric motor and generating a motor current signal corresponding to the detected motor current; and a control unit for controlling operation of said electric motor on the basis of at least the steering torque, said control unit including a target current setting section for setting, on the basis of said steering torque signal, a target current to be supplied to said electric motor and generating a target current signal corresponding to the target current, a proportional plus integral control section for achieving proportional plus integral control action about an offset between said target current signal and said motor current signal so as to effect compensation of said offset, and an overshoot diminishing section operatively connected to said proportional plus integral control section for controlling at least one of a proportional sensitivity and an integral gain of said proportional plus integral control section so as to diminish overshoot occurring in the motor current, wherein said overshoot diminishing section changes said proportional sensitivity and/or said integral gain of said proportional plus integral control section on the basis of said motor current signal supplied from said motor current sensor. - View Dependent Claims (2, 3)
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4. An electric power steering apparatus for a vehicle, comprising:
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a steering torque sensor for detecting a steering torque of a steering system of the vehicle and generating a steering torque signal corresponding to the detected steering torque; an electric motor for applying a steering assist force to the steering system; a motor current sensor for detecting a motor current flowing in said electric motor and generating a motor current signal corresponding to the detected motor current; and a control unit for controlling operation of said electric motor on the basis of at least the steering torque, said control unit including a target current setting section for setting, on the basis of said steering torque signal, a target current to be supplied to said electric motor and generating a target current signal corresponding to the target current, a proportional plus integral control section for achieving proportional plus integral control action about an offset between said target current signal and said motor current signal so as to effect compensation of said offset, and an overshoot diminishing section operatively connected to said proportional plus integral control section for controlling at least one of a proportional sensitivity and an integral gain of said proportional plus integral control section so as to diminish overshoot occurring in the motor current, wherein said overshoot diminishing section changes said proportional sensitivity and/or said integral gain of said proportional plus integral control section on the basis of said offset between said target current signal and said motor current signal. - View Dependent Claims (5)
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6. An electric power steering apparatus for a vehicle, comprising:
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a steering torque sensor for detecting a steering torque of a steering system of the vehicle and generating a steering torque signal corresponding to the detected steering torque; an electric motor for applying a steering assist force to the steering system; a motor current sensor for detecting a motor current flowing in said electric motor and generating a motor current signal corresponding to the detected motor current; and a control unit for controlling operation of said electric motor on the basis of at least the steering torque, said control unit including a target current setting section for setting, on the basis of said steering torque signal, a target current to be supplied to said electric motor and generating a target current signal corresponding to the target current, a proportional plus integral control section for achieving proportional plus integral control action about an offset between said target current signal and said motor current signal so as to effect compensation of said offset, and an overshoot diminishing section operatively connected to said proportional plus integral control section for controlling at least one of a proportional sensitivity and an integral gain of said proportional plus integral control section so as to diminish overshoot occurring in the motor current, wherein said overshoot diminishing section includes an overshoot estimating part for estimating the occurrence of said overshoot on the basis of one of said motor current signal and said offset between said target current signal and said motor current signal, and a proportional and integral coefficient setting part for setting a proportional coefficient and an integral coefficient corresponding to the output from said overshoot estimating part in order to control said proportional sensitivity and/or said integral gain of said proportional plus integral control section. - View Dependent Claims (7, 8, 9, 10)
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Specification