Abstract: A rear wheel steering system includes a rack shaft, a neutral position locking apparatus that restricts the movement of the rack shaft in a rack axis direction, and a pin-driving device that drives a restriction pin. The neutral position locking apparatus has the restriction pin and a pin-receiving portion formed in the rack shaft. The restriction pin has a first pin-sidewall portion slanted with respect to a pin axis and a second pin-sidewall portion parallel to the pin axis. The pin-receiving portion has a first shaft-sidewall portion that contacts the first pin-sidewall portion when the position of the rack shaft in the rack axis direction is at a neutral position, and a second shaft-sidewall portion that contacts the second pin-sidewall portion when the position of the rack shaft in the rack axis direction is at a restriction position different from the neutral position.

Abstract: An auxiliary power supply device that can always supply stable auxiliary power at the time of using an auxiliary power source and an electric power steering device employing the auxiliary power supply device are provided. In the auxiliary power supply device including a discharge circuit selectively constituting a state where a motor is supplied with power from only a battery and a state where the motor is supplied with power from a power source in which an auxiliary power source is connected in series to the battery by PWM control, when the power consumption of the battery is greater than an upper limit, a control circuit is provided which controls the power consumption to return to the upper limit by performing an electric power feedback control using a duty as an amount of operation at the time of turning on and off switching elements by a PWM control on the basis of the difference.

Abstract: In an electric power steering apparatus of the invention, a control circuit determines a command value of drive voltage supplied to a motor drive circuit based on an actual current through a motor and a target current. When the command value exceeds the previous value having a lower limit equivalent to a limit value representing the limit of the power supply from a battery, the control circuit controls the amount of discharge from the auxiliary power supply according to a difference between the command value and the previous value by increasing or decreasing a duty of switching devices. Thus, the power steering apparatus can save the energy of the auxiliary power supply for efficiently using the auxiliary power supply.

Abstract: In an electric power steering apparatus of the invention, a control circuit determines a command value of drive voltage supplied to a motor drive circuit based on an actual current through a motor and a target current. When the command value exceeds the previous value having a lower limit equivalent to a limit value representing the limit of the power supply from a battery, the control circuit controls the amount of discharge from the auxiliary power supply according to a difference between the command value and the previous value by increasing or decreasing a duty of switching devices. Thus, the power steering apparatus can save the energy of the auxiliary power supply for efficiently using the auxiliary power supply.

Abstract: An auxiliary power supply device that can always supply stable auxiliary power at the time of using an auxiliary power source and an electric power steering device employing the auxiliary power supply device are provided. In the auxiliary power supply device 1 including a discharge circuit 15 selectively constituting a state where a motor 5 is supplied with power from only a battery 7 and a state where the motor 5 is supplied with power from a power source in which an auxiliary power source 10 is connected in series to the battery 7 by PWM control, when the power consumption of the battery 7 is greater than an upper limit, a control circuit 20 is provided which controls the power consumption to return to the upper limit by performing an electric power feedback control using a duty as an amount of operation at the time of turning on and off switching elements 12 and 13 by a PWM control on the basis of the difference.

Abstract: A current sensor of a motor controller detects the current applied to a motor drive circuit and thus a phase where a failure cannot be detected would occur without taking any measures. However, an abnormal current monitor section contained in a microcomputer receives a voltage signal of an average value of the currents detected in the current sensor by allowing a signal to pass through a first LPF having a cutoff frequency sufficiently lower than the frequency of a PWM signal. Therefore, whether or not the value is within a predetermined normal range is checked, whereby whether or not some failure containing a failure of the current sensor occurs can be easily determined about every phase.

Abstract: An electric power steering system includes: a band-stop filter 15a having a transfer function G1(s) for suppressing resonance, and a phase compensator 15b having a transfer function G2(s). The above function G1(s) is represented by an expression G1(s)=(s2+2?11?1+?12)/(s2+2?12?1+?12), where s is a Laplace operator, ?11 is a damping coefficient, ?12 is a damping coefficient, and ?1 is an angular frequency. On the other hand, the above function G2(s) is represented by an expression G2(s)=(s2+2?21?2+?22)/(s2+2?22?2+?22),where s is a Laplace operator, ?21 is a damping coefficient, ?22 is a damping coefficient, and ?1 is an angular frequency. Furthermore, the above damping coefficients ?21, ?22 satisfy an expression ?2124 ?22?1.Thus, a filter such as a phase compensator may attain a design freedom while preventing the increase of arithmetic load, whereby both the suppression of resonance and a good assist response in a normal steering speed region, for example, may be achieved.

Abstract: An electric power steering system is provided which is capable of providing a favorable steering feeling without using compensation logics such as of inertia compensation and friction compensation. The electric power steering system includes road-noise suppression control means (213) for controlling a steering assist motor (9) in a manner to damp torque transmission in a higher frequency region representing road noises than a frequency region representing road information. A friction value of a steering mechanism (A) is decreased enough to allow the intrinsic vibrations of the steering mechanism (A) to appear. Rotor inertia of the steering assist motor (9) is set to a value small enough to allow the frequencies of the intrinsic vibrations to be present in the frequency region where the torque transmission is damped by the road-noise suppression control means (213).

Abstract: A controller for a brushless motor determines difference between target currents and detected currents in a dq coordinate system and determines a target voltage applied to an armature winding based on a feedback calculation, such as PI (Proportional Integral) calculation, P (Proportional) calculation, or PID (Proportional Integral Derivative) calculation, to decrease the differences.

Abstract: A current sensor of a motor controller detects the current applied to a motor drive circuit and thus a phase where a failure cannot be detected would occur without taking any measures. However, an abnormal current monitor section contained in a microcomputer receives a voltage signal of an average value of the currents detected in the current sensor by allowing a signal to pass through a first LPF having a cutoff frequency sufficiently lower than the frequency of a PWM signal. Therefore, whether or not the value is within a predetermined normal range is checked, whereby whether or not some failure containing a failure of the current sensor occurs can be easily determined about every phase.

Abstract: A controller for a brushless motor generates a rotation force of a rotor by applying a voltage to an armature winding based on a d-axis target voltage Vd*, a q-axis target voltage Vq*, and a detected rotation position of the rotor. The d-axis target voltage Vd* is determined based on a value obtained by correcting a result of a feedback calculation for a d-axis current with a d-axis correction value ??LqIq, and the q-axis target voltage Vq* is determined based on a value obtained by correcting a result of a feedback calculation for a q-axis current with a q-axis correction value ?LdId+??, in which ? stands for a rotation speed of the rotor, Ld stands for a d-axis self-inductance of the armature winding, Lq stands for a q-axis self-inductance of the armature winding, Id stands for the d-axis current, Iq stands for the q-axis current, and ? stands for a value obtained by multiplying a maximum value of magnetic flux linkage of the armature winding in a field system of the rotor by a factor of (3/2)1/2.

Abstract: An electric power steering system is provided which is capable of providing a favorable steering feeling without using compensation logics such as of inertia compensation and friction compensation. The electric power steering system includes road-noise suppression control means (213) for controlling a steering assist motor (9) in a manner to damp torque transmission in a higher frequency region representing road noises than a frequency region representing road information. A friction value of a steering mechanism (A) is decreased enough to allow the intrinsic vibrations of the steering mechanism (A) to appear. Rotor inertia of the steering assist motor (9) is set to a value small enough to allow the frequencies of the intrinsic vibrations to be present in the frequency region where the torque transmission is damped by the road-noise suppression control means (213).

Abstract: An electric power steering system includes: a band-stop filter 15a having a transfer function G1(s) for suppressing resonance, and a phase compensator 15b having a transfer function G2(s). The above function G1(s) is represented by an expression G1(s)=(s2+2?11?1+?12)/(s2+2?12?1+?12), where s: a Laplace operator, ?11: a damping coefficient, ?12: a damping coefficient, and ?1: an angular frequency. On the other hand, the above function G2(s) is represented by an expression G2(s)=(s2+2?21?2+?22)/(s2+2?22?2+?22), where s: a Laplace operator, ?21: a damping coefficient, ?22: a damping coefficient, and ?1: an angular frequency. Furthermore, the above damping coefficients ?21, ?22 satisfy an expression ?2124 ?22?1. Thus, a filter such as a phase compensator may attain a design freedom while preventing the increase of arithmetic load, whereby both the suppression of resonance and a good assist response in a normal steering speed region, for example, may be achieved.

Abstract: In a current control system for a cylindrical permanent magnet synchronous motor as the drive source of an electric power steering apparatus, proportional gain Kdp and integral gain Kdi of a d-axis current PI control portion 126 are respectively set to K1·Ld and K1·Rd on the basis of d-axis inductance Ld and d-axis resistance Rd of the motor. Further, proportional gain Kqp and integral gain Kqi of a q-axis current PI control portion 128 are respectively set to K2·Lq and K2·Rq on the basis of q-axis inductance Lq and q-axis resistance Rq of the motor (K1 and K2 are optional coefficients). In this case, both of the d-axis resistance Rd and the q-axis resistance Rq have values resulting from adding the external resistance R? including wiring resistance to the internal resistance R of the motor.

Abstract: An electric power steering system causing an electric motor 6 to generate a steering assist force according to a steering torque, includes: a torque sensor 3 for detecting the steering torque; phase compensation means 15a, 15b acting when a target control value of the electric motor 6 is generated based on an output from the torque sensor 3; and means 15c for varying the characteristic of the phase compensation means depending upon whether a steering mode is steer with driving or steer without driving, whereby a loadless steering feeling due to phase lag is not encountered during driving even if vibrations during steer without driving are suppressed by a phase compensator.

Abstract: An electric power steering system includes: an electric motor 6 for generating a steering assist force; a torque sensor 3 for detecting a steering torque; means 10 for generating a control target value for the electric motor 6 according to the detected steering torque; and means 28 for providing a non-interactive control of the electric motor. The system further includes a filter 12 which acts in the process of generating the control target value for the electric motor based on the steering toque. The filter 12 includes: a phase compensator 13 for decreasing a resonant peak gain of the system; and an LPF 12 for decreasing a second peak at a higher frequency than that of the resonant peak. The system is not degraded in the characteristics thereof even though the system provides a non-interactive control for ensuring followability of motor control.

Abstract: In a hydraulic power steering apparatus, when the relative rotation between input and output shafts which are connected by a torsion bar is converted into the relative rotation between an outer valve element and an inner valve element, the ratio of the relative rotation angle of the latter to the relative rotation angle of the former is varied in accordance with an operating condition of a vehicle. The hydraulic pressure to generate steering assist force is controlled in accordance with the relative rotation angles between both valve elements. The outer valve element is capable of relative coaxial rotation to the input and output shafts, and the inner valve element is formed integrally with the input shaft. A swinging member is supported by first, second and third supporting parts which respectively rotate together with the input shaft, the output shaft or the outer valve element.

Abstract: In a hydraulic power steering apparatus, when the relative rotation between input and output shafts which are connected by a torsion bar is converted into the relative rotation between an outer valve element and an inner valve element, the ratio of the relative rotation angle of the latter to the relative rotation angle of the former is varied in accordance with an operating condition of a vehicle. The hydraulic pressure to generate steering assist force is controlled in accordance with the relative rotation angles between both valve elements. The outer valve element is capable of relative coaxial rotation to the input and output shafts, and the inner valve element is formed integrally with the input shaft. A swinging member is supported by first, second and third supporting parts which respectively rotate together with the input shaft, the output shaft or the outer valve element.

Abstract: An electric power steering device capable of attaining the expected control and control characteristics while using a phase compensator, includes a target current setting unit including a compensation unit having an inertia compensating unit for outputting an inertial compensating current value and a damper control unit for outputting a damper control current value, a compensation unit for outputting a compensation current value, a basic assist current setting unit for outputting a basic assist current value, and a phase compensating unit connected with the downstream stage of the basic assist current setting unit for outputting a target current value by performing a phase compensation of an added current value while receiving no influence from the dead zone or the characteristic break points of an assist table for setting the basic assist current value.

Abstract: In a current control system for a cylindrical permanent magnet synchronous motor as the drive source of an electric power steering apparatus, proportional gain Kdp and integral gain Kdi of a d-axis current PI control portion 126 are respectively set to K1-Ld and K1-Rd on the basis of d-axis inductance Ld and d-axis resistance Rd of the motor. Further, proportional gain Kqp and integral gain Kqi of a q-axis current PI control portion 128 are respectively set to K2·Lq and K2·Rq on the basis of q-axis inductance Lq and q-axis resistance Rq of the motor (K1 and K2 are optional coefficients). In this case, both of the d-axis resistance Rd and the q-axis resistance Rq have values resulting from adding the external resistance R′ including wiring resistance to the internal resistance R of the motor.