A method of controlling an electric power assisted steering (EPS) system comprises the steps: During a first mode of operation of the EPS system driving a motor using two inverter bridges simultaneously, the nominal current that is applied to the motor at any time by each bridge being limited to a first value, and during a fault mode of operation driving the motor using only one of the two inverter bridges whereby the nominal current that is applied to the motor at any time in the fault mode is limited to a second value, the method varying the second value as a function of one or more operating parameters of the EPS system whereby the second value is set higher than the first value when it is deemed safe to do so.

A control apparatus for a steering system includes control circuitry configured to perform an angle control process for controlling, to an angle command value, a convertible angle that is convertible into a rotational angle of the electric motor, a predetermined component calculation process for calculating a predetermined component containing at least one of two components that are a viscosity component and a friction component of the steering system, while using a value of a variable regarding a control quantity of the electric motor as an input, and a relationship change process for changing a relationship of an output from a control unit for the steering system to an input to the control unit, based on the predetermined component calculated through the predetermined component calculation process.

A steering control device configured to control a steering device includes a control unit. The control unit is configured to calculate a torque command value which is a target value of the motor torque based on execution of angle control for adjusting a convertible angle which is able to be converted to a rotation angle of the motor to a target angle; calculate the motor control signal based on the torque command value; and change a control gain which is used for the angle control based on a change of a factor influencing a behavior of a vehicle in response to steering.

An electric power steering system includes an electric motor configured to provide power to a steering mechanism of a vehicle. A controller operates the electric motor in response to an input. A flash memory device is in communication with the controller. A temperature sensor provides an output indicative of a temperature of a part of the electric power steering system. The controller is configured to power down or prevent power up of the flash memory device if the temperature of the electric power steering system is outside of a predetermined temperature range. A method of operating an electric power steering system includes measuring a temperature of the electric power assisted steering system and switching off a flash memory device of the electric power steering system if the temperature of the electric power steering system is outside of a predetermined temperature range.

A steering control device controls a steering device that includes an electric motor. The steering control device includes a control unit configured to control an operation of the steering device by controlling the electric motor. The control unit is configured to calculate a control value for controlling the electric motor, to calculate a predetermined component indicating characteristics of the steering device using a value of a variable associated with the control value as an input, and to determine whether a mechanical abnormality has occurred in the steering device based on the calculated predetermined component.

A steering system steers wheels of a vehicle through a shift of a steering shaft. The steering system includes: an electric motor; transmission device that transmits an output of the electric motor to the steering shaft; and a malfunction detector that detects a malfunction of the transmission device based on a rotational angle of the electric motor and a shift distance of the steering shaft.

Methods for estimation of lost temperature increment after system restart for motor coil temperature estimation in an electric power steering apparatus of a motor vehicle with a power pack including an ECU with a temperature sensor and an electric motor. The methods allow to easily recover the lost heat increment value after restart of the system. Consequently, the estimation of the temperature of the motor coils will start from the correct temperature value. Damage of the motor due to overheat can be prevented. Further a more robust system diagnostics and a more accurate torque signal estimation can be provided.

Control circuits control inverter circuits provided in correspondence to the control circuits by a drive mode selected from a plurality of drive modes. A cooperative drive mode is for controlling a current supply to motor windings by a plurality of systems by using a value acquired from the other control circuit via communication. An independent drive mode is for controlling the current supply to the motor windings by the plurality of systems without using the value acquired from the other control circuit. A one-system drive mode is for controlling the current supply to the motor winding by one system without using the value acquired from the other control circuit. The control circuits set the drive mode to a cooperative drive mode when inter-computer communication is normal. The control circuits set the drive mode to an independent drive mode or a one-system drive mode thereby differentiating an output characteristic of a motor from that in the cooperative drive mode.

A steering control device in a seer-by-wire system calculates a current limit presentation command value so as to convey an output-limited state of a turning device to a driver, calculates a steering torque command value on a basis of a physical quantity corresponding to an output torque of the turning device, and calculates a basic reaction force torque command value being a basic value of a reaction force torque command value so that a detection value of a torque sensor follows a target value that is based on the steering torque command value. The control device controls a current flowing to a reaction-force-use rotary electric machine on a basis of the basic reaction force torque command value and the end presentation command value, and increases an absolute value of the current limit presentation command value when the turning device is in the output-limited state.

A vector-control type electric power steering apparatus that applies an assist torque to a steering mechanism of a vehicle, including: a temperature coefficient calculating section to calculate a temperature coefficient depending on a temperature of a control section including the inverter, wherein a dead time compensation of the inverter is performed by estimating compensation signs of 3-phase current model command values in which the dq-phase current command values are converted into a 3-phase current command value model, calculating a first dead time compensation amount based on an inverter applying voltage, calculating a second dead time compensation amount by multiplying the first dead time compensation amount by the temperature coefficient, and adding 2-phase dead time compensation values in which values multiplied the second dead time compensation amount by the compensation signs are converted into 2-phase values, to dq-phase voltage command values.