Abstract: A power steering system includes an EPS and a HPS. At normal times, an assist force required by a steering system is computed based on a steering torque and a vehicle speed, and the required assist force is generated by the EPS and the HPS. The torsional stiffness of a torsion bar of the HPS is equal to or substantially equal to the torsional stiffness of a torsion bar of the EPS. Therefore, even if the EPS malfunctions, it is possible to gain the steering feel similar to that when the EPS is operating properly.

Abstract: A rotation angle detecting device includes a resolver that outputs three-phase signals based on a rotation angle of a rotary shaft, and an R/D converter that acquires the three-phase output signals via signal lines corresponding to the respective phases. The R/D converter determines the rotation angle of the rotary shaft on the basis of the three-phase output signals. The R/D converter includes switching elements that change the potential of the first-phase signal line and the potential of the second-phase signal line, respectively.

Abstract: An electric power steering apparatus includes a power supply and a power supply management unit that controls an operation of the power supply. The power supply includes a main power supply, an auxiliary power supply connected in series to the main power supply, a boost circuit that charges the auxiliary power supply by boosting an output voltage of the main power supply and applying the boosted output voltage to the auxiliary power supply, and a voltage sensor that detects an output voltage of the auxiliary power supply. When a reduction amount per unit time of the output voltage detected by the voltage sensor exceeds a voltage reduction amount over a predetermined time, the power supply management unit determines that an abnormality has occurred in an output destination of the power supply.

Abstract: A torque detecting device and an electric power steering system are provided. A torque sensor includes a first rotor that is fixed to an input shaft and that has a predetermined shaft angle multiplier, and a second rotor that is fixed to an output shaft and that has a shaft angle multiplier different from that of the first rotor. In first to fourth output coils arranged on a stator that is arranged around outer peripheries of the first and second rotors, electric signals having different phases are generated on the basis of a variation of a gap between the stator and the first and second rotors. A twist angle of a torsion bar is calculated on the basis of the electric signals, and a torque that acts between the input shaft and the output shaft is calculated on the basis of the twist angle.

Abstract: Three-phase resolver signals that are output from a resolver upon reception of an excitation signal are captured by a microcomputer. The microcomputer computes a rotation angle of an electric motor on the basis of the three-phase resolver signals. The ratio between an excitation period of the excitation signal and a capturing period of each of the three-phase resolver signals is set to 8:5. A computation period of the rotation angle is set to half of the least common multiple of the excitation period of the excitation signal and the capturing period of each resolver signal.

Abstract: A power steering system includes an EPS and a HPS. At normal times, an assist force required by a steering system is computed based on a steering torque and a vehicle speed, and the required assist force is generated by the EPS and the HPS. The torsional stiffness of a torsion bar of the HPS is equal to or substantially equal to the torsional stiffness of a torsion bar of the EPS. Therefore, even if the EPS malfunctions, it is possible to gain the steering feel similar to that when the EPS is operating properly.

Abstract: A rotation angle detecting device includes a resolver that outputs three-phase signals based on a rotation angle of a rotary shaft, and an R/D converter that acquires the three-phase output signals via signal lines corresponding to the respective phases. The R/D converter determines the rotation angle of the rotary shaft on the basis of the three-phase output signals. The R/D converter includes switching elements that change the potential of the first-phase signal line and the potential of the second-phase signal line, respectively.

Abstract: A torque detecting device and an electric power steering system are provided. A torque sensor includes a first rotor that is fixed to an input shaft and that has a predetermined shaft angle multiplier, and a second rotor that is fixed to an output shaft and that has a shaft angle multiplier different from that of the first rotor. In first to fourth output coils arranged on a stator that is arranged around outer peripheries of the first and second rotors, electric signals having different phases are generated on the basis of a variation of a gap between the stator and the first and second rotors. A twist angle of a torsion bar is calculated on the basis of the electric signals, and a torque that acts between the input shaft and the output shaft is calculated on the basis of the twist angle.

Abstract: A resolver according to the invention includes a stator provided with a plurality of teeth, and first to third phase output coils wound around the teeth. When voltages induced in the first to third phase output coils change based on rotation of a rotor, voltage signals corresponding to an electrical angle of the rotor are output from the output coils. One of the first to third phase output coils is wound around each of the teeth. With respect to each of the phases, the distribution of the numbers of turns of each phase output coils, among the first to third phase output coils, is set to a sinusoidal distribution with respect to the electrical angle of the rotor.

Abstract: In an electric power steering system, an ECU 11 includes two independent microcomputers 17a, 17b that serve as motor control signal generators, and the microcomputers 17a, 17b perform the same current feedback computation. Switching arms 20a, 20b that constitute a driving circuit 18 operate independently of each other, based on motor control signals generated by the corresponding microcomputers 17a, 17b. Each of the microcomputers 17a, 17b determines whether an absolute value of a current deviation of an actual current I (I1, I2) from a current command value exceeds a predetermined threshold value. If the current deviation exceeds the threshold value, it is determined that an abnormality occurs in the system.

Abstract: A rotation angle detection device includes a rotation angle sensor and detection means. Each of sensor signals of the rotation angle sensor has a composite waveform of an nth multiple angle component corresponding to a multiple of the number of phases, and an mth multiple angle component corresponding to a non-multiple of the number of phases. The detection means subtracts an average value of the respective sensor values from the respective sensor values, and extracts values of the mth multiple angle components from the respective sensor values to detect an electric angle having a multiplication factor of angle of m, and converts m mechanical angle estimated values which are estimated based on the electric angle into values of the nth multiple angle component, and compares the converted values with the average value to detect a mechanical angle with one mechanical rotation of a detection target as one cycle.

Abstract: Three-phase resolver signals that are output from a resolver upon reception of an excitation signal are captured by a microcomputer. The microcomputer computes a rotation angle of an electric motor on the basis of the three-phase resolver signals. The ratio between an excitation period of the excitation signal and a capturing period of each of the three-phase resolver signals is set to 8:5. A computation period of the rotation angle is set to half of the least common multiple of the excitation period of the excitation signal and the capturing period of each resolver signal.

Abstract: An electric power steering apparatus includes a power supply and a power supply management unit that controls an operation of the power supply. The power supply includes a main power supply, an auxiliary power supply connected in series to the main power supply, a boost circuit that charges the auxiliary power supply by boosting an output voltage of the main power supply and applying the boosted output voltage to the auxiliary power supply, and a voltage sensor that detects an output voltage of the auxiliary power supply. When a reduction amount per unit time of the output voltage detected by the voltage sensor exceeds a voltage reduction amount over a predetermined time, the power supply management unit determines that an abnormality has occurred in an output destination of the power supply.

Abstract: When a failed Hall IC cannot be identified through determination as to whether any of output voltages falls outside a predetermined output range and determination as to whether any of the output voltages has steeply varied, a microcomputer determines whether the directions of steering torques converted from the output voltages are the same. Then, when the directions of the converted steering torques are the same, the average of these output voltages is used to calculate a temporary torque, and then power assist control is continued, that is, specifically, assisting force applied to a steering system is slowly and gradually decreased, on the basis of the temporary torque.

Abstract: In an electric power steering system, an ECU 11 that controls the operation of the system includes three independent microcomputers 18u, 18v, 18w that perform phase current feedback control with respect to the corresponding phases, so that sinusoidal current is applied to each phase of the motor 12 as a non-connected motor. Also, each of the microcomputers 18u, 18v, 18w monitors a deviation of an actual current value from a phase current command value, with respect to each of two phases other than the corresponding phase, and determines that an abnormality occurs in the phase in question when the deviation exceeds a predetermined threshold value. When two of the microcomputers 18u, 18v, 18w determine that the abnormality occurs in the remaining one phase, the ECU 11 confirms the determination that the phase in question is in an abnormal condition.

Abstract: In an electric power steering system, an ECU 11 that controls the operation of the system includes three independent microcomputers 18u, 18v, 18w that perform phase current feedback control with respect to the corresponding phases, so that sinusoidal current is applied to each phase of the motor 12 as a non-connected motor. Also, each of the microcomputers 18u, 18v, 18w monitors a deviation of an actual current value from a phase current command value, with respect to each of two phases other than the corresponding phase, and determines that an abnormality occurs in the phase in question when the deviation exceeds a predetermined threshold value. When two of the microcomputers 18u, 18v, 18w determine that the abnormality occurs in the remaining one phase, the ECU 11 confirms the determination that the phase in question is in an abnormal condition.

Abstract: In an electric power steering system, an ECU 11 includes two independent microcomputers 17a, 17b that serve as motor control signal generators, and the microcomputers 17a, 17b perform the same current feedback computation. Switching arms 20a, 20b that constitute a driving circuit 18 operate independently of each other, based on motor control signals generated by the corresponding microcomputers 17a, 17b. Each of the microcomputers 17a, 17b determines whether an absolute value of a current deviation of an actual current I (I1, I2) from a current command value exceeds a predetermined threshold value. If the current deviation exceeds the threshold value, it is determined that an abnormality occurs in the system.

Abstract: When a failed Hall IC cannot be identified through determination as to whether any of output voltages falls outside a predetermined output range and determination as to whether any of the output voltages has steeply varied, a microcomputer determines whether the directions of steering torques converted from the output voltages are the same. Then, when the directions of the converted steering torques are the same, the average of these output voltages is used to calculate a temporary torque, and then power assist control is continued, that is, specifically, assisting force applied to a steering system is slowly and gradually decreased, on the basis of the temporary torque.

Abstract: In a resolver and an electric power steering apparatus that uses the resolver, one ends of resolver coils that are provided at regular intervals with respect to the rotation center of a resolver rotor are electrically connected at one connection point, and the voltage at the connection point is maintained at a predetermined reference voltage. If at least one of the condition that the square sum Fs does not satisfy the condition F1<Fs<F2 (the square sum Fs is not within a predetermined first range) and the condition that the sum Fa does not satisfy the condition |Fa|<F3 (the sum Fa is not within a predetermined second range) is satisfied, the ECU determines that an abnormality has occurred in the resolver.

Abstract: A steering angle ?t detected by the torque sensor is read at S900. Then, an electrical angle ?m corresponding to a motor rotational angle is read at S902. At S908 through S922, motor rotational numbers are calculated based on ?t, ?m and the rotational number of a handle, and a correct rotational number of the handle is calculated from the motor rotational number which is the nearest to an integer of all of the calculated motor rotational numbers. Thereafter, an absolute steering angle which is not influenced by various errors is calculated based on the calculated rotational number of the handle and the steering angle ?t detected by the torque sensor.