Steering control apparatus

Patent metadata

Field	Value
Publication number	US-9975571-B2
Application number	US-201715612653-A
Country	US
Kind code	B2
Filing date	Jun 2, 2017
Priority date	Jun 10, 2016
Publication date	May 22, 2018
Grant date	May 22, 2018

Abstract

Using an update amount, an update amount calculating circuit manipulates a phase-control angle so as to perform feedback control such that a steering torque corresponds to a target torque. The steering torque is obtained by reducing a steering torque in magnitude by a predetermined value. The phase-control angle is used to convert a current command value to a value of a fixed coordinate system, for example. Using a guard value, a guard processing circuit performs a guard process on a current command value set by a command value setting circuit, so that the current command value becomes the current command value. The guard value is used to determine an appropriate range for a variation in the current command value in accordance with an amount by which the steering torque exceeds in magnitude the target torque.

First claim

What is claimed is:

1. A steering control apparatus for controlling a steering device to assist a driver in steering a vehicle, the steering device including a synchronous motor to generate an assist torque, and a power converting circuit to apply a voltage to the synchronous motor,
the steering control apparatus comprising:
a current control circuit to manipulate a voltage to be applied to the synchronous motor from the power converting circuit so as to adjust a current flowing through the synchronous motor to a current command value;
a phase-control angle manipulating circuit to manipulate a phase-control angle so as to perform feedback control such that a detection value of a steering torque corresponds to a target torque, the phase-control angle determining a phase of the current command value, the steering torque being a torque input to a steering shaft of the steering device;
a command value setting circuit to increase an absolute value of the current command value on condition that an amount by which the detection value exceeds in magnitude the target torque is equal to or greater than a threshold value, and reduce the absolute value of the current command value on condition that the exceeding amount is smaller than the threshold value; and
a guard processing circuit to perform a guard process on the current command value set by the command value setting circuit, in a manner that does not permit a reduction in the absolute value of the current command value, the guard process being performed on condition that the exceeding amount is equal to or greater than the threshold value.

2. The steering control apparatus according to claim 1 , wherein
a preceding value of the current command value subjected to the guard process is increased in magnitude by a specified amount so as to obtain a lower limit guard value, and
the guard processing circuit is configured to perform the guard process such that the current command value is equal to or greater in magnitude than the lower limit guard value, the guard process being performed on condition that the exceeding amount is equal to or greater than the threshold value.

3. The steering control apparatus according to claim 1 , wherein
the command value setting circuit is configured to reduce the current command value when at least one of a temperature of the synchronous motor and a temperature of the power converting circuit is determined to be equal to or higher than a specified temperature, and
the guard processing circuit is configured to, when at least one of the temperature of the synchronous motor and the temperature of the power converting circuit is equal to or higher than the specified temperature, perform the guard process on the current command value in a manner that permits a reduction in the magnitude of the current command value if the exceeding amount is equal to or greater than the threshold value.

4. The steering control apparatus according to claim 3 , wherein
the guard processing circuit is configured to, when at least one of the temperature of the synchronous motor and the temperature of the power converting circuit is determined to be equal to or higher than the specified temperature, perform the guard process on the current command value in a manner that reduces the magnitude of the current command value if the exceeding amount is equal to or greater than the threshold value.

5. The steering control apparatus according to claim 1 , wherein
the guard processing circuit is configured to perform the guard process on the current command value set by the command value setting circuit, in a manner that does not permit an increase in the absolute value of the current command value, the guard process being performed on condition that the exceeding amount is smaller than the threshold value.

6. The steering control apparatus according to claim 1 , wherein
the guard process is a variation guard process, and
the guard processing circuit is configured to carry out an absolute value guard process such that the current command value subjected to the variation guard process is between upper and lower limits inclusive.

7. The steering control apparatus according to claim 1 , wherein
the guard processing circuit is configured to determine whether a speed of the vehicle is equal to or higher than a vehicle speed threshold value before performing the guard process, and
the guard processing circuit is configured to permit only a reduction in the current command value when the speed of the vehicle is equal to or higher than the vehicle speed threshold value, and perform the guard process when the speed of the vehicle is lower than the vehicle speed threshold value.

Assignees

• Jtekt Corp

Inventors

• Anraku Koji

Classifications

• B62D5/0484

  for reaction to failures, e.g. limp home · CPC title

• B62D5/0496

  by using a temperature sensor · CPC title

• B62D5/049

  detecting sensor failures · CPC title

• B62D5/0463 Primary

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

• B62D5/0487

  detecting motor faults (B62D5/0496 takes precedence) · CPC title