Abstract: In a rotation angle detection device, each of an angular interval between a first magnetic sensor and a second magnetic sensor and an angular interval between the second magnetic sensor and a third magnetic sensor is 60° in electrical angle. When two magnetic sensors including the second magnetic sensor among the three magnetic sensors are operating properly, if the two properly operating magnetic sensors including the second magnetic sensor sense one and the same magnetic pole for a prescribed number of multiple consecutive sampling periods, the rotation angle is computed based on the output signals from the two magnetic sensors. When only the second magnetic sensor malfunctions, if the first and the third magnetic sensors sense one and the same magnetic pole for the prescribed number of multiple consecutive sampling periods, the rotation angle is computed based on the output signals from the two properly operating magnetic sensors.

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: An electric power steering system includes a motor that applies assist force to a steering system, and updates a motor resistance (Rm) that is a value indicating a resistance of the motor. Specifically, the motor resistance (Rm) is updated on the basis of the fact that an induced voltage (EX) of the motor is smaller than a first determination value (GA). In addition, when the induced voltage (EX) is smaller than or equal to a second determination value (GB), a divided value that is obtained by dividing a motor voltage (Vm) by a motor current (Im) is set as a new motor resistance (Rm).

Abstract: A command current setting portion has a target value corrector that calculates d-axis and q-axis current command values idc, iqc that are to be supplied to an open-loop controller, based on d-axis and q-axis current target values id*, iq*. When d-axis and q-axis voltage target value vd*, vq* calculated from the d-axis and q-axis current target values id*, iq* by the motor circuit equations exceed a voltage limit, this target value corrector 26 corrects the d-axis and q-axis current target values id*, iq* by the field weakening control such that d-axis and q-axis voltages vd, vq and d-axis and q-axis currents id, iq satisfy ?(vd2+vq2)?Vlim and ?(id2+iq2)?Ilim respectively. The d-axis and q-axis current command values idc, iqc are obtained by this correction.

Abstract: A motor is driven based on an axis current value in a rotating coordinate system that rotates in accordance with a control angle that is a rotational angle used in a control. The control angle is calculated by adding an addition angle to an immediately preceding value of the control angle in each predetermined calculation cycle. A command steering torque is set based on a predetermined steering angle-torque characteristic. The addition angle is calculated based on the deviation of a detected steering torque from a command steering torque. The addition angle based on the deviation is changed when a predetermined condition is satisfied.

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: A steering assist operation is performed, which includes a motor control unit that controls a motor, and the steering assist operation does not require a rotational angle sensor. 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, which is calculated by a control angle calculation unit. The control angle calculation unit obtains, at every predetermined calculation cycle, a present value of the control angle by adding an addition angle to an immediately preceding value of the control angle. An addition angle calculation unit calculates the addition angle to be added to the control angle through a proportional-integral control based on a torque deviation from a command torque set by a command torque setting unit.

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: Angular widths of respective magnetic poles of a detection rotor are stored and divisions are set for respective magnetic pole pairs. Based on output signals from first and second magnetic sensors, a rotation angle computation unit computes first and second rotation angles that are rotation angles within the corresponding division. Based on the angular widths, the rotation angle computation unit identifies the magnetic pole sensed by the first magnetic sensor and computes a first absolute rotation angle using the first rotation angle. Based on the identified magnetic pole and the second rotation angle, the rotation angle computation unit computes a second absolute rotation angle. The rotation angle of the detection rotor is computed based on the first and second absolute angles.

Abstract: A motor control device of the present invention includes: target electric current value setting units (15 and 16) that set target electric current values that should be supplied to a motor (1), basic voltage value computing units (511, 521, 51a, and 52a) that compute basic voltage values for driving the motor, a rotation angle speed computing unit (23) that computes a rotation angle speed of the motor, correction value computing units (50, 512, 515, 516, 522, 525, and 526) that compute correction values for correcting the basic voltage values based on motor electric current values and a rotation angle speed of the motor, correcting units (513 and 523) that obtain voltage command values by correcting the basic voltage values by the correction values computed by the correction value computing units, and a driving unit (13) that drives the motor by using voltage command values.

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 low speed region position estimating portion is designed to be suitable for when the motor is operating in a low speed region, and estimates a low speed estimated rotational position ?^L. A high speed region position estimating portion is designed to be suitable for when the motor is operating in a high speed region, and estimates a high speed estimated rotational position ?^H. A dividing portion obtains a divided estimated rotational position ?^M by internally dividing the low speed estimated rotational position ?^L and the high speed estimated rotational position ?^H. A rotation speed calculating portion obtains a rotation speed ? of a rotor based on an output signal from a steering sensor. The rotational position of the rotor is then obtained by selecting one of i) the low speed estimated rotational position ?^L, the high speed estimated rotational position ?^H, or the divided estimated rotational position ?^M, based on that rotation speed ?.

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: An electric power steering system includes a motor that applies assist force to a steering system, and updates a motor resistance (Rm) that is a value indicating a resistance of the motor. Specifically, the motor resistance (Rm) is updated on the basis of the fact that an induced voltage (EX) of the motor is smaller than a first determination value (GA). In addition, when the induced voltage (EX) is smaller than or equal to a second determination value (GB), a divided value that is obtained by dividing a motor voltage (Vm) by a motor current (Im) is set as a new motor resistance (Rm).

Abstract: A motor control device includes: a motor-current detection unit; a rotational-angular-speed calculation unit for calculating a rotational angular speed of a motor; a rotational-angle-change-amount calculation unit for multiplying the rotational angular speed by a predetermined time so as to calculate a motor-rotational-angle change amount within a predetermined time; a basic-drive-value calculation unit for calculating a basic drive value for driving the motor; a correction-value calculation unit for calculating a correction value for correcting the basic drive value based on the motor current and the motor-rotational-angle change amount; a correction unit for evaluating the motor drive value by correcting the basic drive value by the correction value; and a drive unit for driving the motor by using the motor drive value evaluated by the correction unit.

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 device for controlling a d-axis current and a q-axis current on dq coordinates to control a motor, includes a q-axis current command value setting unit which sets a q-axis current command value, an upper limit/lower limit setting unit which sets an upper limit and a lower limit of the q-axis current, a comparing unit which compares the q-axis current command value set by the q-axis current command value setting unit and the upper limit and the lower limit set by the upper limit/lower limit setting unit, a q-axis current command value limiting unit which puts a limit on the q-axis current command value in accordance with a comparison result by the comparing unit, and a d-axis current command value setting unit which sets a d-axis current command value on the basis of the q-axis current command value limited by the q-axis current command value limiting unit.

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 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.