Abstract: In a rotation angle detecting device, a first magnetic sensor and a second magnetic sensor are disposed at an interval of an electrical angle of 120 degrees around a rotation center axis of a rotor. An output signal of the first magnetic sensor is expressed by V1=sin ?, and an output signal of the second magnetic sensor is expressed by V2=sin(?+120). A determination device determines whether both the magnetic sensors are normal, or there is a failure in at least one of the magnetic sensors, based on whether an expression of L?V12+V22+V1·V2?0.75?U is satisfied, where L is a lower limit and U is an upper limit.

Abstract: In an electric power steering system, a low-pass filter executes a low-pass filtering process on a detected steering torque value detected by a torque sensor. A steering torque deviation computing unit computes a deviation ?T between a detected steering torque value T* obtained through the low-pass filtering process and the detected steering torque value detected by the torque sensor. A PI control unit generates a vibration compensation value used to lead the detected steering torque value to the steering torque value obtained through the low-pass filtering process, by executing PI computation on the steering torque deviation computed by the steering torque deviation computing unit.

Abstract: An electric power steering system calculates a motor resistance Rm using a resistance map, and calculates an estimated inducted voltage based on a motor current and a motor voltage. If the estimated induced voltage is determined as being equal to or smaller than a determination value that is set in accordance with the current level, the electric power steering system calculates a motor resistance (estimated motor resistance Rma) and updates the resistance map based on the estimated motor resistance Rma.

Abstract: A motor control device has characteristic information that indicates a correlation between a rotation speed and a current of a motor. The motor control device sets a rotation speed characteristic value that is a reference value of the rotation speed of the motor and a current characteristic value that is a reference value of the current of the motor on the basis of the characteristic information. The motor control device calculates an estimated rotation speed on the basis of a measured value of a voltage that is applied to the motor, a measured value of the current, the current characteristic value, a voltage characteristic value, the rotation speed characteristic value and a counter-electromotive force constant.

Abstract: A motor is driven by the ?-axis current of a ?? coordinate system that is an imaginary rotating coordinate system. A command current value preparation unit sets the ?-axis command current value based on the command steering torque and the detected steering torque. The command current value preparation unit includes a command current increase/decrease amount calculation unit and an addition unit. The command current increase/decrease amount calculation unit calculates the current increase/decrease amount for the command current value based on the sign of the command steering torque and the deviation of the detected steering torque from the command steering torque. The current increase/decrease amount calculated by the command current increase/decrease amount calculation unit is added to the immediately preceding value of the command current value by the addition unit. Thus, the command current value in the present calculation cycle is calculated.

Abstract: A current increase-decrease amount (?I?*) computed by a command current increase-decrease amount computing unit is added to an immediately preceding value (I?*(n?1)) of a command current value (I?*) in an adder. The command current value (I?*) obtained by the adder is given to a high/low limit limiter. The high/low limit limiter limits the command current value (I?*), obtained by the adder, to a value between a low limit value (?min (?min?0)) and a high limit value (?max (?max>?min)). A high limit value setting unit obtains the high limit value (?max) corresponding to the vehicle speed detected by the vehicle speed sensor, from a vehicle speed-vs.-high limit value map set by a map creating/updating unit, and sets the obtained high limit value (?max) in the high/low limit limiter.

Abstract: A motor control unit controls a motor including a rotor and a stator facing the rotor. A current drive unit drives the motor at an axis current value of a rotating coordinate system that rotates in accordance with a control angle that is a rotational angle used in a control. An addition angle calculation unit calculates an addition angle to be added to the control angle. A control angle calculation unit obtains, at every predetermined calculation cycle, a present value of the control angle by adding the addition angle that is calculated by the addition angle calculation unit to an immediately preceding value of the control angle. A torque detection unit detects a torque that is other than a motor torque and that is applied to a drive target driven by the motor. A command torque setting unit sets a command torque to be applied to the drive target.

Abstract: When the estimated motor temperature becomes equal to or higher than the first predetermined temperature, an addition angle correction unit temporarily decreases the absolute value of the addition angle output from an addition angle limiter at time intervals. The addition angle correction unit makes the time interval shorter as the estimated motor temperature increases. When the time interval becomes equal to or shorter than the predetermined threshold, that is, when the estimated motor temperature becomes equal to or higher than the second predetermined temperature that is higher than the first predetermined temperature, the addition angle correction unit notifies a command current value changing unit of a current stop command. Thus, the ?-axis command current value is changed to 0, and therefore the steering mode is shifted to the manual steer mode.

Abstract: A motor controller controls a motor including a rotor and a stator opposed to the rotor. The motor controller includes an electric current driving unit which drives the motor with an axis electric current value defined in a rotating coordinate system defined with respect to a control angle that is a rotation angle for control, a control angle computing unit which computes a current value of the control angle by adding an addition angle to a previous value of the control angle in each predetermined computing cycle, and an addition angle computing unit which computes the addition angle according to a torque to be generated by the motor or a response of the motor to the axis electric current value.

Abstract: A motor control unit controls a motor including a rotor and a stator facing the rotor. A current drive unit drives the motor at an axis current value of a rotating coordinate system that rotates in accordance with a control angle that is a rotational angle used in a control. An addition angle calculation unit calculates an addition angle to be added to the control angle. A control angle calculation unit obtains, at every predetermined calculation cycle, a present value of the control angle by adding the addition angle that is calculated by the addition angle calculation unit to an immediately preceding value of the control angle. An angular speed calculation unit calculates an angular speed of the rotor. An addition angle correction unit corrects the addition angle based on the angular speed calculated by the angular speed calculation unit. A filtering unit filters the angular speed calculated by the angular speed calculation unit.

Abstract: A motor control unit includes a detected steering torque correction unit that corrects the detected steering torque that is detected by a torque sensor and then subjected to a limitation process by a steering torque limiter. When the absolute value of the detected steering torque is equal to or smaller than a predetermined value, the detected steering torque correction unit corrects the detected steering torque to 0. When the absolute value of the detected steering torque is larger than the predetermined value, the detected steering torque correction unit outputs the detected steering torque without correction. A PI control unit calculates the addition angle based on the deviation of the control torque obtained through correction by the detected steering torque correction unit from the command steering torque.

Abstract: An electric power steering system determines a steering state of a steering wheel on the basis of a current (Im) of a motor applying assist force to a steering system and a steering speed (?s) of the steering wheel. A state where the steering wheel is retained at a position other than a neutral position is a retained state, and a state where the steering wheel is placed at the neutral position is a neutral state. When the steering speed (?s) is lower than a determination value (?a) and the motor current (Im) is larger than a reference value (Ix), it is determined whether the steering state is the neutral state. When the steering speed (?s) is lower than the determination value (?a), the motor current (Im) is larger than the reference value (Ix), and the steering state is determined to be the neutral state at immediately preceding determination, the steering state is determined to be the neutral state.

Abstract: In an electric power steering system, a back electromotive force constant is calculated on the basis of a steering angular velocity and an estimated induced voltage. Then, a rotation angular velocity of a motor is calculated as an estimated rotation angular velocity on the basis of a motor current, a motor voltage, the back electromotive force constant and a motor resistance.

Abstract: An electric power steering system calculates a motor resistance Rm using a resistance map, and calculates an estimated inducted voltage based on a motor current and a motor voltage. If the estimated induced voltage is determined as being equal to or smaller than a determination value that is set in accordance with the current level, the electric power steering system calculates a motor resistance (estimated motor resistance Rma) and updates the resistance map based on the estimated motor resistance Rma.

Abstract: A F/B gain control unit computes a first change component by executing torque feedback control based on a torque deviation using a feedback gain that is computed by a F/B gain variable control unit. The F/B gain variable control unit computes one of two different feedback gains that correspond to a “first computation mode” in which the first change component is used as an addition angle and a “second computation mode” in which a value obtained by correcting the first change component by an estimated motor rotation angular velocity is used as the addition angle, respectively. A feedback gain used in the first computation mode is set such that a response at the feedback gain is higher than that at a feedback gain used in the second computation mode.

Abstract: An ECU that controls a motor includes: a target current value setting unit setting a target current; a voltage detecting unit detecting a detected voltage on the basis of a detection signal from a voltage sensor; a voltage calculation unit calculating an estimated voltage on the basis of a power supply voltage of a battery; and an induced voltage observer calculating an induced voltage generated at the motor using an inter-terminal voltage based on the estimated voltage when the target current is set to a value other than zero; whereas the induced voltage observer calculates the induced voltage using an inter-terminal voltage based on the detected voltage when the target current is set to zero.

Abstract: Rotation angle computation modes include a normal mode and a simple mode. In normal mode, a rotation angle of an input shaft is computed based on output signals from first and second magnetic sensors, which are sampled at two sampling timings. In simple mode, the rotation angle of the input shaft is computed based on the output signals from the first and second magnetic sensors, which are sampled at one sampling timing, and an amplitude ratio between the output signals from the magnetic sensors set in advance. After a power supply is turned on, the rotation angle is computed in the simple mode until a condition that the rotation angle of the input shaft can be computed in the normal mode even if the immediately preceding value of the rotation angle of the input shaft is not present is satisfied. Then, the rotation angle is computed in the normal mode.

Abstract: Sinusoidal signals (S1, S2) having a phase difference of 120° are output from two magnetic sensors in accordance with rotation of an input shaft. A first rotation angle computation unit computes a rotation angle ?(n) on the basis of output signals S1(n), S1(n?1), S2(n), S2(n?1) from the magnetic sensors, which are sampled at two sampling timings. At this time, the first rotation angle computation unit computes the rotation angle ?(n) on the assumption that there are no variations of amplitudes of the output signals (S1, S2) from each one of the two sensors due to temperature changes between the two sampling timings.

Abstract: In a phase difference detector, a first phase difference computation unit computes a value of E(i)·C corresponding to one and the same given magnetic pole sensed by the two magnetic sensors with use of six output signals sampled at three different timings while the two magnetic sensors are sensing the given magnetic pole when a rotary body is rotating. E is an angular width error correction value, and C is a phase difference between two signals. The first phase difference computation unit executes this process until values of E(i)·C corresponding to all the magnetic poles are computed. After that, the first phase difference computation unit computes the phase difference between the output signals with use of the values of E(i)·C corresponding to all the magnetic poles and the number (m) of the magnetic poles.

Abstract: In a rotation angle detection device, when a condition that two sensors among three magnetic sensors sense one and the same magnetic pole for three consecutive sampling periods is satisfied, a rotation angle is computed based on output signals from the two sensors, sampled at three sampling timings. When the output signals sampled at the three sampling timings satisfy a prescribed requirement, an angular width error correction value corresponding to the magnetic pole sensed by the two sensors and amplitudes are computed, and stored in association with the magnetic pole. If the condition is not satisfied, the rotation angle is computed based on the information stored in a memory and the output signals from two sensors among the three magnetic sensors, the two magnetic sensors including one of the three magnetic sensors, which detects the magnetic pole of which the angular width error correction value is stored in the memory.