A power steering apparatus and a control circuit for a power steering apparatus are provided. The power steering apparatus detects an abnormality in the power steering apparatus based on whether there is a periodic change within a predetermined frequency range with respect to the number of rotations of an electric motor, a steering velocity, or a steering torque.

A closed-loop circuit is detected based on a short-circuit failure of a motor control switching element of a motor drive circuit and a cutoff switching element. A motor control device including a motor, a motor drive circuit (10a) that is connected to a power supply device and the motor and controls the output of the motor, and a processing unit for detecting a closed-loop circuit formed by the motor and the motor drive circuit (10a) based on a short-circuit failure of switching elements arranged in the motor drive circuit (10a).

A steering system includes a prioritized torque sensor, a redundant torque sensor, a controller, a first signal line, a second signal line, and a common signal line. Each of the first signal line and the second signal line connects the prioritized torque sensor and the controller. The common signal line connects the redundant torque sensor and the controller. The prioritized torque sensor is configured to transmit, via the first signal line, a first prioritized detection signal. The prioritized torque sensor is configured to transmit, via the second signal line, a second prioritized detection signal. The redundant torque sensor is configured to transmit, via the common signal line, a first redundant detection signal and a second redundant detection signal.

A power relay unit includes a high potential side relay connected so that an anode of a parasitic diode is on a high potential side and a cathode is on a low potential side, and a low potential side relay connected in series with a low potential side of the high potential side relay so that a cathode of a parasitic diode is on a high potential side and an anode is on a low potential side. A relay-to-relay connection line connects an intermediate point between the first high potential side relay and the first low potential side relay and an intermediate point between the second high potential side relay and the second low potential side relay. A control unit controls an on/off operation of the first high potential side relay based on a first supply voltage, a second supply voltage, and a relay intermediate voltage.

A motor control apparatus includes an inverter, a driver, a negative voltage circuit, a voltage dividing circuit, and a detection unit. The inverter includes an upper-arm switching element and a lower-arm switching element to supply a voltage of a node between the upper-arm switching element and the lower-arm switching element to a motor as a phase voltage. The driver applies a first voltage or a second voltage to the upper-arm switching element to control and turn the upper-arm switching element on and off. The negative voltage circuit supplies a voltage lower than the voltage of the node to the driver as the second voltage. The voltage dividing circuit performs voltage division between the negative voltage circuit and a negative power supply. The detection unit outputs a signal based on a voltage resulting from the voltage division by the voltage dividing circuit.

With an object of allowing steering wheel operation to be carried out easily at a normal time and when an abnormality occurs, the invention includes a motor having two windings and a control unit having two control systems that supply control signals to each winding of the motor and when an abnormality occurs in one winding of the motor or in one system inside the control unit, a supply of current to the winding in which the abnormality has occurred is cut to zero, and the motor is driven by a predetermined current necessary at a normal time being supplied to the other winding, while at a time of a normal drive when no abnormality has occurred, the current supply is shared between the two windings, whereby the motor is driven.

A vehicle control system includes a central ECU configured to calculate target outputs of actuators, and relay devices each disposed in a communication path between the central ECU and a corresponding actuator among the actuators. The relay devices include a specific relay device capable of communicating with a specific actuator related to driving control, braking control, or steering control of a vehicle. The specific relay device among the relay devices includes a specific abnormality diagnosis unit configured to diagnose an abnormality in the specific relay device, and a backup calculation unit capable of calculating a control amount of the specific actuator coupled to the specific relay device. A relay device other than the specific relay device among the relay devices does not have a self-diagnosis function.

Technical solutions are described for mitigating braking torque in a motor of a steering system caused by a FET short. For example, an example mitigation system includes a mitigation module that adjusts a motor torque in response to a FET short. The mitigation system further includes a mitigation-enable module that selectively enables and disables the mitigation module based on a handwheel torque signal. Further, the mitigation system includes a damping module that reduces the motor torque based on a motor velocity signal for the motor.

An electric power steering apparatus has a rotation detection device for calculating an absolute angle that includes a sensor section that detects a rotation of a motor and outputs a mechanical angle and a count value. The rotation detection device also includes a signal acquisition unit that obtains the mechanical angle and the count value from the sensor section, and an absolute angle calculator that calculates an absolute angle based on the mechanical angle and the count value. Where one rotation of the motor is divided into indefinite regions and definite regions, the absolute angle calculator uses the count value from the definite regions to calculate the absolute angle.

An electric power steering apparatus has a rotation detection device that can recover from abnormalities in calculating an absolute angle. The rotation detection device includes a signal acquirer that acquires a mechanical angle and a count value from a sensor, and an absolute angle calculator that calculates an absolute angle based on the mechanical angle and the count value. The rotation detection device further includes an abnormality determiner that determines abnormalities in the calculation of the absolute angle. The absolute angle calculator stores an absolute angle hold value prior to the detection of the abnormality the absolute angle. When the abnormality of the absolute angle is resolved, the absolute angle calculator calculates a recovery-time absolute angle, and returns to a normal-time absolute angle calculation.