Anti-loss-of-assistance for electric motor
First Claim
1. A method of operating an electric power steering system installed on a vehicle, the electric power steering system comprising an electric motor and a controller that receives a desired assist torque value and supplies a pulse-width modulation duty cycle to the electric motor, the method comprising the steps of:
- determining a value of electrical resistance of a wiring harness and at least one connector disposed to provide electrical power from a power source to the controller;
determining a value of steering assistance torque available from the motor based on the determined electrical resistance of the wiring harness and the at least one connector;
controlling the electric motor to achieve a nominal value of power steering assist torque when the value of steering assistance torque available from the motor is sufficient to achieve the nominal value of power steering assist torque; and
controlling the electric motor to achieve a reduced value of power steering assist torque less than the nominal value when the value of steering assistance torque available from the motor is not sufficient to achieve the nominal value of power steering assist torque.
1 Assignment
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Accused Products
Abstract
A method of operating an electric power steering system installed on a vehicle. The electric power steering system includes a controller that receives a desired assist torque value and supplies a pulse-width modulation duty cycle to an electric motor. The method includes the step of controlling the electric motor to achieve a nominal value of power steering assist torque when the electrical power available to the motor is sufficient to achieve the nominal value of power steering assist torque. The method further includes the step of controlling the electric motor to achieve a reduced value of power steering assist torque less than the nominal value when the electrical power available to the motor is not sufficient to achieve the nominal value of power steering assist torque.
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Citations
20 Claims
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1. A method of operating an electric power steering system installed on a vehicle, the electric power steering system comprising an electric motor and a controller that receives a desired assist torque value and supplies a pulse-width modulation duty cycle to the electric motor, the method comprising the steps of:
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determining a value of electrical resistance of a wiring harness and at least one connector disposed to provide electrical power from a power source to the controller; determining a value of steering assistance torque available from the motor based on the determined electrical resistance of the wiring harness and the at least one connector; controlling the electric motor to achieve a nominal value of power steering assist torque when the value of steering assistance torque available from the motor is sufficient to achieve the nominal value of power steering assist torque; and controlling the electric motor to achieve a reduced value of power steering assist torque less than the nominal value when the value of steering assistance torque available from the motor is not sufficient to achieve the nominal value of power steering assist torque. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A controller for an electric power steering system that includes an electric motor;
- the controller programmed to;
receive a desired assist torque value; supply a pulse-width modulation duty cycle to the electric motor; determine a value of electrical resistance of a wiring harness and at least one connector disposed to provide electrical power from a power source to the controller; determine a value of steering assistance torque available from the motor based on the determined electrical resistance of the wiring harness and the at least one connector; control the electric motor to achieve a nominal value of power steering assist torque when the value of steering assistance torque available from the motor is sufficient to achieve the nominal value of power steering assist torque; and control the electric motor to achieve a reduced value of power steering assist torque less than the nominal value when the value of steering assistance torque available from the motor is not sufficient to achieve the nominal value of power steering assist torque. - View Dependent Claims (9, 10, 11, 12, 13)
- the controller programmed to;
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14. A method of operating a system comprising an electric motor and a controller that receives a desired assist torque value and supplies a pulse-width modulation duty cycle to the electric motor, the method comprising the steps of:
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determining a value of electrical resistance of a wiring harness and at least one connector disposed to provide electrical power from a power source to the controller; determining a value of steering assistance torque available from the motor based on the determined electrical resistance of the wiring harness and the at least one connector; controlling the electric motor to achieve a nominal value of assist torque when the value of steering assistance torque available from the motor is sufficient to achieve the nominal value of assist torque; and controlling the electric motor to achieve a reduced value of assist torque less than the nominal value when the value of steering assistance torque available from the motor is not sufficient to achieve the nominal value of assist torque. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification