Control apparatus and method of motor driven power steering system

Patent metadata

Field	Value
Publication number	US-10414431-B2
Application number	US-201715686585-A
Country	US
Kind code	B2
Filing date	Aug 25, 2017
Priority date	Aug 26, 2016
Publication date	Sep 17, 2019
Grant date	Sep 17, 2019

Abstract

A control apparatus of an MDPS system may include: a current supply unit configured to drive a motor by injecting a preset frequency and magnitude of current to the motor; a torque sensor configured to sense a torque of a steering shaft; a hall sensor fault determination unit configured to determine whether a fault has occurred in a hall sensor; a torque signal processing unit configured to process a signal outputted from the torque sensor and calculate the magnitude of a torque signal; an encoder fault determination unit configured to determine whether a fault has occurred in an encoder, using the torque signal outputted from the torque signal processing unit; and a motor control unit configured to acquire a position of a motor rotor according to the determination results of the hall sensor fault determination unit and the encoder fault determination unit, and control the operation of the motor.

First claim

What is claimed is:

1. A motor driven power steering (MDPS) system for a vehicle, the MDPS system comprising:
a motor configure to drive a steering shaft of the vehicle;
a current supply configured to apply a current to operate the motor;
a torque sensor connected to the steering shaft and configured to output a torque signal according to rotation of the steering shaft, wherein the torque signal comprises a first ripple caused by the current and a second ripple caused by steering effort of a driver of the vehicle;
a hall sensor connected to the motor and configured to output a hall sensor signal according to rotation of the motor;
an encoder connected to the motor and configured to output an encoder signal according to rotation of the motor; and
at least one controller configured to acquire a position of a rotor of the motor using the torque signal, the hall sensor signal and the encoder signal and further configured to control the current supply using the position of the rotor,
wherein, in acquiring the position of the rotor, the controller is configured:
to determine whether the hall sensor is at fault based on at least one of the torque signal and a status value of the hall sensor;
to determine whether the encoder is at fault based on the torque signal;
when it is determined that the hall sensor is at fault and the encoder is normal, to acquire the position of the rotor using the encoder signal;
when it is determined that the encoder is at fault and the hall sensor is normal, to acquire the position of the rotor using the hall sensor signal; and
when it is determined that both of the encoder and the hall sensor are at fault, to calculate a magnitude of the first ripple of the torque signal caused by the current applied to the motor and to estimate the position of the rotor based on the calculated magnitude.

2. The MDPS system of claim 1 , wherein the at least one controller is configured to determine a position value corresponding to the calculated magnitude, and configured to estimate the position of the motor rotor by applying the detected position value to a finally detected position of the rotor.

3. The MDPS system of claim 1 , wherein the at least one controller is configured to determine a fault in the hall sensor; when the status value of the hall sensor corresponds to a preset fault determination value.

4. The MDPS system of claim 1 , wherein the at least one controller is configured to determine a fault in the hall sensor y when the status value of the hall sensor is not changed and a torque sensed by the torque sensor is larger by a preset value than a preset normal range.

5. The MDPS system of claim 1 , wherein the current supply comprises:
a current frequency injection unit configured to inject a current of a preset frequency and magnitude to a d-axis of the motor; and
a motor current control unit configured to couple the current injected by the current frequency injection unit to a current applied to the d-axis of the motor, and configured to perform current vector control to apply a current to the d- and q-axes of the motor.

6. The MDPS system of claim 1 , wherein the at least one controller is configured to determine a fault in the encoder using a lookup table storing magnitude of a torque ripple for an encoder fault.

7. A method for controlling a motor driven power steering (MDPS) system of a vehicle, the method comprising:
receiving, by at least one controller, a torque signal from a torque sensor connected to a steering shaft of the vehicle as the steering shaft rotates,
receiving, by the at least one controller, a hall sensor signal from a hall sensor connected to a motor of the MDPS system as the motor rotates;
receiving, by the at least one controller, an encoder signal from an encoder connected to the motor as the motor rotates;
acquiring, by the at least one controller, a position of a rotor of the motor using the torque signal, the hall sensor signal and the encoder signal; and
controlling, by the at least one controller, a current supplied from a current supply to the motor using the position of the rotor,
wherein the at least one controller determines whether at least one of the hall sensor and the encoder is at fault,
wherein when it is determined that the hall sensor is at fault and the encoder is normal the at least one controller acquires the position of the rotor using the encoder signal,
wherein when it is determined that the encoder is at fault and the hall sensor is normal the at least one controller acquires the position of the rotor using the hall sensor signal,
wherein the torque signal comprises a first ripple caused by the current applied to the motor and a second ripple caused by steering effort of a driver of the vehicle,
wherein when it is determined that both of the encoder and the hall sensor are at fault, in acquiring the position of the rotor, the at least one controller calculates a magnitude of the torque signal generated by the current applied to the motor and estimates the position of the rotor based on the calculated magnitude,
when it is determined that both of the encoder and the hall sensor are at fault, to calculate a magnitude of the first ripple of the torque signal caused by the current applied to the motor and to estimate the position of the rotor based on the calculated magnitude.

Assignees

• Hyundai Mobis Co Ltd

Inventors

• Kim Moon Su
• Yoo Ji Hoon

Classifications

• H02P6/16

  Circuit arrangements for detecting position · CPC title

• B62D5/0484

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

• B62D5/049 Primary

  detecting sensor failures · CPC title

• B60W2510/202

  Steering torque · CPC title

• B62D5/0493

  detecting processor errors, e.g. plausibility of steering direction · CPC title