JP5125216B2 - Electric power steering device - Google Patents

Description

  The present invention includes a steering torque detecting means for detecting a steering torque input from a steering wheel to a steering mechanism for turning steered wheels, an electric motor for generating a steering assist torque applied to a steering shaft of the steering mechanism, The present invention relates to an electric power steering apparatus including a steering assist force control unit that calculates a current command value based on a steering torque detected by a steering torque detection unit and drives and controls the electric motor.

Conventionally, in a vehicle such as a passenger car or a truck, a steering assisting force is applied to a steering mechanism by driving an electric motor according to a steering torque by which the driver steers the steering wheel as a steering device, thereby reducing the steering force of the driver. Electric power steering devices are widespread.
By the way, in a vehicle in which a steering wheel, that is, a steered wheel also serves as a driving wheel for driving, such as a front engine front wheel drive (FF) vehicle and a four wheel drive (4WD) vehicle, layout restrictions in the engine room are large. It is difficult to establish equal rigidity on the left and right of the differential device that distributes the torque output from the engine to the left and right wheels. For example, due to the arrangement of the engine and the transmission, the difference between the left and right shaft lengths of the drive shaft connected to the differential device is large, and the left and right joint bending angles may differ. For this reason, the vehicle travel is disturbed, the steering steering force and the steering holding force are changed, or the driver is forced to perform a difficult and complicated steering operation.

  Specifically, due to the unbalance of the driving force transmitted to the steered wheels, the phenomenon that the steering wheel is taken at the time of acceleration and start, that is, the change of the driving force is large and the vehicle speed change amount is large, that is, the so-called torque steer occurs. There is. Also, during braking, the driving path is disturbed during sudden braking with large changes in braking force and large vehicle deceleration due to unbalanced braking force transmitted to the wheels and forces from various directions on the tire and suspension. There is a problem that a phenomenon that causes vehicle deflection, that is, a vehicle single flow occurs during braking.

Therefore, conventionally, in order to effectively suppress the torque steer that occurs in a vehicle in which the steered wheels and the drive wheels are combined, the longitudinal acceleration α is calculated, and the longitudinal acceleration α exceeds the positive lower limit α ₀ , When there is a possibility of occurrence of torque steer, an assist correction amount A that increases with an increase in the longitudinal acceleration α is calculated, and the assist correction amount A is used to calculate a target value for drive control of the steering assist motor. There has been known an electric power steering device in which the target assisting force is corrected to be increased (see, for example, Patent Document 1).
Japanese Patent Laying-Open No. 2006-213085 (first page, FIG. 3)

  However, in the conventional example described in Patent Document 1, since the assist correction amount A is determined only by the acceleration α, the assist correction amount is obtained even in a state where the torque steer during acceleration does not actually occur. There is an unresolved problem that A is determined and the driver feels uncomfortable, and there is an unresolved problem that no consideration is given to the vehicle flow during braking.

  Accordingly, the present invention has been made paying attention to the unsolved problems of the above-described conventional example, and provides an electric power steering device capable of optimally suppressing acceleration torque steer and vehicle fragmentation during deceleration. It is aimed.

In order to achieve the above object, an electric power steering apparatus according to a first aspect of the present invention includes a steering torque detecting means for detecting a steering torque input to a steering mechanism for turning steered wheels, and a steering assist torque applied to the steering mechanism. An electric power steering apparatus comprising: an electric motor that generates a power; and a steering assist force control unit that calculates a current command value based on a steering torque detected by at least the steering torque detection unit and controls driving of the electric motor. A self-aligning torque estimating means for estimating a self-aligning torque input to the steering mechanism from the steered wheel side, and a front-rear acceleration / deceleration detecting means for detecting a vehicle longitudinal acceleration / deceleration, and the steering assist force control The means is the self-aligning torque estimated by the self-aligning torque estimating means. Comprising a steering assist force correction means for correcting the steering assist force generated by the electric motor to suppress unstable behavior of the vehicle caused at the time of acceleration and deceleration based on the acceleration detected by finely the longitudinal acceleration detecting means, said The steering assist force correcting means is configured to increase the correction amount for correcting the steering assist force as the self-aligning torque increases .

The electric power steering apparatus according to claim 2 is the invention according to claim 1, before Symbol steering assist force correction means, so as to increase the correction amount for correcting the steering assist force as the longitudinal acceleration is greater It is characterized by being configured.

Furthermore, the electric power steering apparatus according to claim 3 is configured such that, in the invention according to claim 1 or 2 , the steering assist force correcting means corrects the steering assist force by correcting the current command value. It is characterized by being.
Still further, according to a fourth aspect of the present invention, there is provided the electric power steering apparatus according to the third aspect of the invention, wherein the steering assist force correcting means sets a correction amount that increases the current command value when the vehicle is accelerated. It is characterized by being.

According to a fifth aspect of the present invention, in the electric power steering apparatus according to the third or fourth aspect of the invention, the steering assist force correcting means sets a correction amount that reduces the current command value when the vehicle decelerates. It is characterized by being composed.
Furthermore, the electric power steering apparatus according to claim 6, in the invention according to any one of claims 1 to 5, wherein the steering assist force correction means, the steering torque of the correction amount detected by said steering torque detecting means It is characterized by being configured to change in accordance with the above.

Furthermore, the electric power steering apparatus according to claim 7 is the invention according to any one of claims 1 to 5, comprising a steering angle detection means for detecting a steering angle of the steering mechanism, the steering assist force correction The means is configured to change the correction amount in accordance with the steering angle detected by the steering angle detection means.

  According to the present invention, the electric motor generates the unstable behavior of the vehicle that occurs during acceleration / deceleration based on the self-aligning torque detected by the self-aligning torque detecting means and the acceleration / deceleration detected by the acceleration / deceleration detecting means. Since the steering assist force to be corrected is corrected, it is possible to appropriately suppress the torque steer that occurs during acceleration including when the vehicle starts, and to appropriately suppress the vehicle single flow during braking that occurs during braking of the vehicle. can get.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an overall configuration diagram showing a first embodiment when the present invention is applied to a front engine front wheel drive vehicle. In the figure, reference numeral 1 denotes a battery mounted on a normal vehicle. The battery voltage Vb output from the battery 1 is input to the control device 3 as steering assist force control means via the fuse 2. The control device 3 drives and controls the electric motor 5 that generates a steering assist force for the steering system.

Here, the electric motor 5 is constituted by, for example, a brushless motor driven by three-phase alternating current, and operates as a steering assist force generation motor that generates a steering assist force with respect to the steering device 10.
The steering device 10 has a steering shaft 12 on which a steering wheel 11 is mounted. The steering shaft 12 is connected to a steering gear mechanism 13 of, for example, a rack and pinion type, and the steering gear mechanism 13 is connected to a connecting mechanism 14 such as a tie rod. The left and right steered wheels 15 to which driving force from an engine (not shown) is transmitted are connected.

The steering shaft 12 is connected to the electric motor 5 via a speed reduction mechanism 16 composed of, for example, a worm gear, and the steering assist force generated by the electric motor 5 is transmitted to the steering shaft 12 via the speed reduction mechanism 16. The
The steering shaft 12 is provided with a steering torque sensor 17 for detecting the steering torque T input to the steering wheel 11, and the electric motor 5 has a rotation angle sensor 18 for detecting the motor rotation angle θm. The steering torque T detected by the steering torque sensor 17 and the motor rotation angle θm detected by the rotation angle sensor 18 are input to the control device 3.

Here, the steering torque sensor 17 detects the steering torque applied to the steering wheel 11 and transmitted to the steering shaft 12, and for example, a torsion bar in which the steering torque is inserted between an input shaft and an output shaft (not shown). The torsional angular displacement is converted into an electrical signal, and the torsional angular displacement is detected with a magnetic signal and converted into an electrical signal.
Furthermore, the vehicle speed Vx detected by the vehicle speed sensor 19 that detects the vehicle speed Vx of the vehicle is input to the control device 3.

  As shown in FIG. 2, the control device 3 includes a current command value calculation unit 21 that calculates a steering assist current command value Iref as a current command value based on the steering torque T and the vehicle speed V, and a rotation angle sensor of the electric motor 5. A motor rotation information calculation unit 22 that calculates an electrical angle θe, a motor angular velocity ωm, and a motor angular acceleration αm based on the motor rotation angle θm detected in 18, and a steering auxiliary current command value Iref calculated by the current command value calculation unit 21. From the steering auxiliary force correction unit 23 as a steering auxiliary force correction unit that calculates the steering auxiliary current correction value Iref ′ by correcting the vehicle so as to suppress the unstable behavior of the vehicle that occurs during acceleration / deceleration. Based on the command value compensator 24 for compensating the steering assist current correction value Iref ′ to be output, and the d-q based on the compensated current command value Iref ″ compensated by the command value compensator 24. A dq-axis current command value calculation unit 25 that calculates a current command value, calculates a three-phase current command value Iaref, Ibref, and Icref by performing two-phase / three-phase conversion on the calculated dq-axis current command value; A motor current control unit that forms and outputs motor currents Iu to Iw for driving and controlling the electric motor 5 based on the three-phase current command values Iaref, Ibref and Icref calculated by the dq-axis current command value calculation unit 25. 26.

The steering assist current command value calculation unit 21 calculates a steering assist current command value Iref based on the steering torque T and the vehicle speed Vx with reference to the steering assist current command value calculation map shown in FIG.
As shown in FIG. 3, this steering assist torque command value calculation map is a parabolic curve having the steering torque T on the horizontal axis, the steering assist current command value Iref on the vertical axis, and the vehicle speed Vx as a parameter. The steering assist torque command value Iref is maintained at “0” while the steering torque T is between “0” and a set value Ts1 in the vicinity thereof, and the steering torque T is set at the set value Ts1. When it exceeds, initially, the steering assist command value Iref increases relatively gently with respect to the increase of the steering torque T, but when the steering torque T further increases, the steering assist torque command value Iref increases steeply with respect to the increase. The characteristic curve is set so that the inclination becomes smaller as the vehicle speed increases.

  The motor rotation information calculation unit 22 differentiates the motor rotation angle θm detected by the rotation angle sensor 18 and the electric angle conversion unit 30 that converts the motor rotation angle θm detected by the rotation angle sensor 18 into the electric angle θe. An angular velocity calculation unit 31 that calculates the motor angular velocity ωm and an angular acceleration calculation unit 32 that calculates the motor angular acceleration αm by differentiating the motor angular velocity ωm calculated by the angular velocity calculation unit 31 are provided.

  The steering assist force correction unit 23 includes a self-aligning torque estimation unit (hereinafter referred to as a SAT estimation unit) 41 as a self-aligning torque detection unit, a front-rear acceleration / deceleration detection unit 42 as a front-rear acceleration / deceleration detection unit, and an acceleration / deceleration correction gain. A calculation unit 43, a multiplier 44, an absolute value conversion circuit 45 that calculates an absolute value of the steering torque T detected by the steering torque sensor 17, a steering torque correction gain calculation unit 46, a multiplier 47, a limiter 48, and an adder 49 are provided. ing.

The SAT estimation unit 41 estimates the self-aligning torque SAT input to the steered wheels 15. The principle of calculating the self-aligning torque SAT will be described with reference to FIG. 4 showing the state of torque generated between the road surface and the steering.
That is, when the driver steers the steering wheel 11, the steering torque T is generated, and the electric motor 5 generates the assist torque Tm according to the steering torque T. As a result, the steered wheels 15 are steered and a self-aligning torque SAT is generated as a reaction force.

Further, at that time, torque serving as a steering resistance of the steering wheel 11 is generated by the inertia J and friction (static friction) Fr of the electric motor 5. Considering the balance of these forces, the following equation of motion can be obtained:
J ・ αm + Fr ・ sign (ωm) + SAT = Tm + T (1)
Here, when the above equation (1) is Laplace transformed with the initial value zero and the self-aligning torque SAT is solved, the following equation (2) is obtained.

SAT (s) = Tm (s) + T (s) − J · αm (s) − Fr · sign (ωm (s)) (2)
As can be seen from the above equation (2), the inertia J and static friction Fr of the electric motor 12 are obtained in advance as constants, so that the self-aligning torque is obtained from the motor angular velocity ωm, rotational angular acceleration αm, assist torque Tm, and steering torque T SAT can be detected. Here, since the assist torque Tm is proportional to the steering assist current command value Iref, the steering assist current command value Iref is applied instead of the assist torque Tm.
The longitudinal acceleration / deceleration detector 42 differentiates the vehicle speed Vx detected by the vehicle speed sensor 19 to calculate the longitudinal acceleration / deceleration αx in the vehicle longitudinal direction.

  The acceleration / deceleration correction gain calculation unit 43 calculates the acceleration / deceleration correction gain Gα by referring to the acceleration / deceleration correction gain calculation map shown in FIG. 5 based on the longitudinal acceleration / deceleration αx detected by the longitudinal acceleration / deceleration detection unit 42. The acceleration / deceleration correction gain Gα is supplied from the SAT estimation unit 41 to the multiplier 44 to which the self-aligning torque SAT is input. As shown in FIG. 5, this acceleration / deceleration correction gain calculation map maintains the acceleration / deceleration correction gain Gα “0” between the longitudinal acceleration / deceleration αx from 0 to a predetermined positive value + α1 representing acceleration, When the acceleration / deceleration αx exceeds a predetermined value + α1, the acceleration / deceleration correction gain Gα increases according to the characteristic line L1 according to the increase of the longitudinal acceleration / deceleration αx, and conversely, the predetermined value of the negative value representing the deceleration from 0 to the longitudinal acceleration / deceleration αx. The acceleration / deceleration correction gain Gα is maintained at “0” until −α2, and when the longitudinal acceleration / deceleration αx exceeds a predetermined value −α2, the acceleration / deceleration according to the characteristic line L2 increases as the negative value of the longitudinal acceleration / deceleration αx increases. The correction gain Gα is set so as to increase steeply in the negative direction. Here, the characteristic curve L1 represents a phenomenon in which the steering wheel is taken at the time of acceleration and start, that is, a so-called torque steer during acceleration, in which the change of the driving force is large and the amount of change in the vehicle speed is large due to the imbalance of the driving force transmitted to the steered wheels. The characteristic curve L2 is set to a value corresponding to the steering shaft 12 from the steered wheel 15 side of the steering mechanism 10 by applying unbalanced braking force transmitted to the wheel during deceleration and forces from various directions to the tire and suspension. This is set to a value that can suppress the phenomenon of causing vehicle deflection that disturbs the traveling path, that is, the vehicle half-flow during braking, at the time of sudden braking in which a torque that tries to twist is generated and the braking force changes greatly and the vehicle deceleration is large. Note that FIG. 5 illustrates the case where the characteristic curves L1 and L2 are set according to the torque steering during acceleration and the vehicle flow during deceleration depending on whether the acceleration / deceleration αx represents acceleration or deceleration. The same characteristic curve may be applied when acceleration / deceleration αx represents acceleration and when it represents deceleration.

  The steering torque correction gain calculation unit 46 refers to the steering torque correction gain calculation map shown in FIG. 6 on the basis of the absolute value | T | of the steering torque T input from the absolute value conversion circuit 45, and the steering torque correction gain Gt. And the steering torque correction gain Gt is supplied to the multiplier 47 to which the multiplication output of the multiplier 44 is input. In this steering angle correction gain calculation map, as shown in FIG. 6, when the absolute value | T | of the steering torque T is between “0” and a predetermined value T1, the steering torque correction gain Gt is set to “1”. When the absolute value | T | of the steering torque T exceeds the predetermined value T1, the absolute value | T | of the steering torque T decreases relatively steeply as the absolute value | T | After that, the characteristic line L3 is set so that the steering torque correction gain Gt becomes “0” regardless of the increase of the steering torque absolute value | T |.

  The limiter 48 calculates the steering assist force correction value As by limiting the multiplication output output from the multiplier 47 to be within a predetermined range between the positive and negative maximum values. Then, the steering assist force correction value As output from the limiter 48 is supplied to an adder 49 connected to the output side of the steering assist command value calculation unit 21, and the steering assist current command value Iref is corrected to assist steering assist. A current correction value Iref ′ is calculated.

The command value compensation unit 24 is based on the convergence compensation unit 51 that compensates the convergence of the yaw rate based on the motor angular velocity ωm calculated by the angular velocity calculation unit 31, and the motor angular acceleration αm calculated by the angular acceleration calculation unit 32. And at least an inertia compensator 52 that compensates for the torque equivalent generated by the inertia of the electric motor 12 to prevent deterioration of the feeling of inertia or control responsiveness.
Here, the convergence compensation unit 51 receives the vehicle speed V detected by the vehicle speed sensor 19 and the motor angular velocity ωm calculated by the angular velocity calculation unit 31, and the steering wheel 1 swings to improve the yaw convergence of the vehicle. A convergence compensation value Ic is calculated by multiplying the motor angular velocity ωm by a convergence control gain Kv that is changed according to the vehicle speed Vx so as to apply a brake to the turning operation.

  Then, the inertia compensation value Ii calculated by the inertia compensation unit 52 and the convergence compensation value Ic calculated by the convergence compensation unit 51 are added by the adder 53 to calculate a command compensation value Icom, and this command compensation value Icom is added to the steering assist current correction value Iref ′ output from the steering assist force correction unit 23 by the adder 54 to calculate the compensated current command value Iref ″, and this compensated current command value Iref ″ is calculated as d−q. It is output to the shaft current command value calculation unit 25.

  The dq-axis current command value calculation unit 25 includes a d-axis target current calculation unit 61 that calculates a d-axis target current Idref based on the post-compensation steering assist torque command value Iref ″ and the motor angular velocity ωm, and a motor rotation. The d-axis EMF component ed (θ) and q-axis EMF of the dq-axis induced voltage model EMF (Electro Magnetic Force) based on the electrical angle θe and the motor angular velocity ωm input from the electrical angle conversion unit 30 of the information calculation unit 22. An induced voltage model calculation unit 62 for calculating the component eq (θ), a d-axis EMF component ed (θ) output from the induced voltage model calculation unit 62, a q-axis EMF component eq (θ), and a d-axis target current calculation Q-axis for calculating the q-axis target current Iqref based on the d-axis target current Idref output from the unit 61, the compensated steering assist current command value Iref ″, and the motor angular velocity ωm The three-phase current command values Iaref and Ibref are obtained by combining the standard current calculation unit 63, the d-axis target current Idref output from the d-axis target current calculation unit 61, and the q-axis target current Iqref output from the q-axis target current calculation unit 63. And a two-phase / three-phase converter 64 for converting to Icref.

  The motor current control unit 26 includes a motor current detection unit 70 that detects motor currents Ia, Ib, and Ic supplied to the three-phase coil of the electric motor 12, and a two-phase / 3 of the dq-axis current command value calculation unit 25. Subtraction to obtain respective phase current deviations ΔIa, ΔIb, and ΔIc by individually subtracting motor currents Ia, Ib, and Ic detected by motor current detection unit 70 from current command values Iaref, Ibref, and Icref input from phase conversion unit 64. 71a, 71b and 71c and a current control unit 72 for calculating the voltage command values Va, Vb and Vc by performing proportional-integral control on the obtained phase current deviations ΔIa, ΔIb and ΔIc, and the current control unit 72 and the like. The pulse width modulation (PWM) is performed by calculating the duty ratio of each phase of the electric motor 5 by performing duty calculation based on the output voltage command values Va, Vb and Vc. A pulse width modulation control unit 73 that forms an inverter control signal consisting of a signal, and three-phase motor currents Ia, Ib, and Ic based on the inverter control signal output from the pulse width modulation control unit 73 to form the electric motor 5 And an inverter 74 for outputting to the output.

Next, the operation of the above embodiment will be described.
Assume that the vehicle is stopped with the steering wheel 11 in a neutral position in a straight traveling state. When the steering wheel 11 is not steered in this state, the steering torque T detected by the steering torque sensor 17 is “0”, and the vehicle speed Vx is also “0”. When the steering assist current command value calculation map is referred to at 21 based on the steering torque T and the vehicle speed Vx, the steering assist current command value Iref becomes “0”.

  At this time, since the electric motor 5 is also stopped, the motor angular velocity ωm and the motor angular acceleration αm calculated by the motor rotation information calculation unit 22 are both “0”. Since T is “0”, the steering torque correction gain Gt calculated by the steering torque correction gain calculation unit 46 is “1”, but the self-aligning torque SAT estimated by the SAT estimation unit 41 is also “0”. Since the vehicle is stopped, the longitudinal acceleration / deceleration αx detected by the longitudinal acceleration / deceleration detecting unit 42 is also “0”, and the acceleration / deceleration correction gain Gα calculated by the acceleration / deceleration correction gain calculating unit 43 is also Since it is “0”, the steering assist force correction value As is “0”, and the steering assist current correction value Iref ′ is also “0”.

Since the motor angular velocity ωm and the motor angular acceleration αm are also “0” in the command value compensation unit 24, the convergence compensation value Ic calculated by the convergence compensation unit 51 and the inertia compensation value Ii calculated by the inertia compensation unit 52 are also obtained. Since it is “0”, the command compensation value Icom is also “0”, and the post-compensation steering assist current command value Iref ″ output from the adder 54 is also “0”.
For this reason, the three-phase current command values Iaref, Ibref, and Icref calculated by the dq-axis current command value calculation unit 25 are also zero, and the electric motor 5 is stopped, so that it is detected by the motor current detection unit 70. Since the motor currents Ia, Ib and Ic are also “0”, the current deviations ΔIa, ΔIb and ΔIc output from the subtracters 71a, 71b and 71c are also “0”, so that the voltage output from the current control unit 72 is The command values Va, Vb and Vc are also “0”, the output of the inverter control signal from the pulse width modulation circuit 73 is stopped, and the inverter 74 is stopped, so that the motor currents Ia, Ib supplied to the electric motor 5 are stopped. And Ic continue to be “0”, and the electric motor 5 continues to be stopped.

When the vehicle is stopped and the steering wheel 11 is steered to perform a so-called stationary operation, the steering torque T detected by the steering torque sensor 17 correspondingly becomes a relatively large value. The steering assist current command value Iref calculated by the value calculator 21 increases rapidly according to the steering torque T.
At this time, in the steering assist force correcting unit 23, the motor angular velocity ωm and the motor angular acceleration αm are both “0” in the SAT estimating unit 41, but the steering assist current command value Iref corresponding to the steering torque T and the assist torque Tm Therefore, the self-aligning torque SAT calculated by the equation (2) is an added value of the steering torque T and the steering assist current value Iref. However, since the vehicle is stopped and the vehicle speed Vx detected by the vehicle speed sensor 19 is “0”, the longitudinal acceleration / deceleration αx detected by the longitudinal acceleration / deceleration detector 42 is also “0”. Since the acceleration / deceleration correction gain Gα calculated by the speed correction gain calculation unit 43 maintains “0”, the multiplication output of the multiplier 44 becomes “0”, and the absolute value | T | Therefore, the steering torque correction gain Gt also becomes a small value, the multiplication output of the multiplier 47 becomes “0”, and the steering assist force correction value As maintains “0”.

  For this reason, the steering assist current command value Iref calculated by the steering assist current command value calculation unit 21 is supplied to the adder 54 as it is, and since the electric motor 5 is stopped even in this state, the motor angular velocity ωm and the motor angular acceleration αm. Also continues to “0”, the convergence compensation value Ic calculated by the convergence compensation unit 51 of the command value compensation unit 24 and the inertia compensation value Ii calculated by the inertia compensation unit 52 also maintain “0”. The compensation value Icom is also “0”.

Therefore, the steering assist current command value Iref is supplied as it is from the adder 54 to the dq axis current command value calculation unit 25, and the dq axis current command value calculation unit 25 responds to the steering assist current command value Iref. Three-phase current command values Iaref, Ibref and Icref are output to the motor current control unit 26.
Accordingly, the three-phase current command values Iaref, Ibref and Icref are output as current deviations ΔIa, ΔIb and ΔIc as they are from the subtracters 71a, 71b and 71c, and the voltage command values Varef, Vbref after the PI is controlled by the current control unit 72. And Vcref are converted to Vcref and supplied to the pulse width modulation circuit 73, an inverter control signal is output from the pulse width modulation circuit 73, and this is supplied to the inverter 74. Electric currents Ia, Ib and Ic are output, and the electric motor 5 is rotationally driven to generate a steering assist force corresponding to the steering torque T.

  The steering assist force generated by the electric motor 5 is transmitted to the steering shaft 12 to which the steering force from the steering wheel 11 is transmitted via the speed reduction mechanism 16, whereby the steering force and the steering assist force are transmitted to the steering gear mechanism. 13 is converted into a linear motion in the vehicle width direction, and the left and right steered wheels 15 are steered via the coupling mechanism 14, and the steered wheels 15 can be steered with light steering torque.

  When the electric motor 5 is driven and controlled, the motor angular velocity ωm and the motor angular acceleration αm calculated by the motor rotation information calculation unit 22 are increased, whereby the command value compensation unit 24 performs the convergence compensation value Ic and the inertia. The compensation value Ii is calculated, and these are added to calculate the command compensation value Icom, which is supplied to the adder 54, and is added to the steering assist current correction value Iref ′ to be compensated steering assist current command value Iref. By calculating “”, command value compensation processing is performed.

As described above, when the vehicle is stopped, the torque steering during acceleration that occurs during acceleration does not occur, and the vehicle flow during braking that occurs during deceleration does not occur, and the steering assist force correction calculated by the steering assist force correction unit 23 is performed. The value As also remains zero.
However, when the vehicle is started from a stopped state and accelerated in a straight traveling state, for example, the vehicle is a front engine front wheel drive vehicle in this acceleration state, and the driving force is caused by the unbalance of the driving force transmitted to the steered wheels. As a result, the phenomenon that the steering wheel 11 is taken, that is, the so-called acceleration torque steer occurs.

Thus, torque steer is generated when the vehicle starts running at a relatively large acceleration in a straight traveling state, and the disturbance disturbance turning torque at this time is obtained from the steered wheel 15 to the coupling mechanism 14 such as a tie rod, the steering gear mechanism, and the like. 13 is transmitted to the steering shaft 12 as reverse input torque.
Since the reverse input torque transmitted to the steering shaft 12 tries to rotate the steering wheel 11, when the driver holds the steering wheel 11 to prevent this, the steering torque sensor 17 detects the reverse input torque. Thus, the steering assist current command value calculation unit 21 calculates the steering assist current command value Iref corresponding to the reverse input torque.

  At this time, in the steering assist force correcting unit 23, the steering wheel 11 is in a steered state held by the driver, and the electric motor 5 does not rotate. Since the motor angular velocity ωm and the motor angular acceleration αm are maintained at “0”, the steering torque T detected by the steering torque sensor 17 in the SAT estimation unit 41 and the steering auxiliary current command value calculated by the steering auxiliary current command value calculation unit 21. A value obtained by adding the value Iref is estimated as the self-aligning torque SAT. For this reason, the self-aligning torque SAT estimated by the SAT estimating unit 41 is supplied to the multiplier 44. At this time, since the vehicle is in an accelerating state, the longitudinal acceleration / deceleration αx detected by the longitudinal acceleration / deceleration detecting unit 42 increases in the positive direction, and the acceleration / deceleration correction calculated by the acceleration / deceleration correction gain calculating unit 43 accordingly. The gain Gα increases from “0”, and a multiplier output obtained by multiplying the self-aligning torque SAT by the acceleration / deceleration correction gain Gα is obtained from the multiplier 44.

  On the other hand, since the steering torque T detected by the steering torque sensor 17 is only a reverse input torque due to torque steer and is a relatively small value, the steering torque correction gain Gt calculated by the steering torque correction gain calculator 46 is The multiplication output of the multiplier 44 is output from the multiplier 47 as it is, and is output to the adder 49 through the limiter 48 as the steering assist force correction value As.

Therefore, a value obtained by adding the steering assist force correction value As to the steering assist current command value Iref calculated by the steering assist current command value calculation unit 21 by the adder 49 is supplied to the adder 54 as the steering assist current correction value Iref ′. Is done.
At this time, since the electric motor 5 continues to be in the rotation stop state, the motor angular velocity ωm and the motor angular acceleration αm calculated by the motor rotation information calculation unit 22 continue to be “0”, so that the command value compensation unit 24 The command compensation value Icom continues to “0”, and the steering assist current correction value Iref ′ is supplied as it is to the dq axis current command value calculation unit 25 as the compensated steering assist current command value Iref ″. The shaft current command value calculation unit 25 calculates three-phase current command values Iaref, Ibref, and Icref that cause the electric motor 5 to generate a steering assist force that cancels the reverse input torque caused by torque steer.

  For this reason, the motor current control unit 26 outputs motor currents Ia, Ib, and Ic corresponding to the three-phase current command values Iaref, Ibref, and Icref to the electric motor 5, and the electric motor 5 performs reverse input torque due to torque steer. A steering assist force that cancels out is generated, and this steering assist force is transmitted to the steering shaft 12 via the speed reduction mechanism 16 to cancel the reverse input torque caused by the torque steer during acceleration.

  Further, when the vehicle starts while steering the steering wheel 11 at a relatively large longitudinal acceleration / deceleration αx, torque steer during acceleration occurs as in the case described above, but the steering wheel 11 is steered. As a result, when the absolute value | T | of the steering torque T detected by the steering torque sensor 17 exceeds the predetermined value T1, the steering torque correction gain calculation unit 46 responds to an increase in the absolute value | T | When the steering torque correction gain Gt calculated in step 1 is decreased from “1”, the multiplication output output from the multiplier 47 is relatively decreased at the start in the straight traveling, and the steering assist force correction value As is decreased, the electric motor 5 is driven and controlled based on the steering assist current command value Iref calculated by the steering assist current command value calculation unit 21. And generating a steering assisting force corresponding to the steering torque T by the electric motor 5, it is possible to perform light steering.

  At this time, when the electric motor 5 is rotationally driven, the motor angular velocity ωm and the motor angular angular velocity αm calculated by the motor rotation information calculating unit 22 are increased from “0”, so that the convergence compensation unit 51 performs the motor angular velocity. The convergence compensation value Ic is calculated based on ωm, and the inertia compensation value Ii is calculated based on the motor angular acceleration αm by the inertia compensation unit 52. These are added by the adder 53 and added as the command correction value Icom. And is added to the steering assist current correction value Iref ′ output from the adder 49 to calculate a compensated steering assist current command value Iref ″, which is supplied to the dq axis current command value calculation unit 25. Therefore, the dq-axis current command value calculation unit 25 calculates the three-phase current command values Iaref, Ibref and Icref corresponding to the compensated current command value Iref ″. It is, the electric motor 5 by the motor current control unit 26 on the basis of these controlled driven to generate optimum steering assist force.

  On the other hand, when the vehicle is in a slow start state where the vehicle travels straight at a relatively small longitudinal acceleration / deceleration αx, torque steer during acceleration hardly occurs, and the steering torque T detected by the steering torque sensor 17 is substantially “0”. The steering assist current command value Iref calculated by the steering assist current command value calculation unit 21 is substantially “0”. In the steering assist force correcting unit 23, the front / rear acceleration / deceleration αx detected by the front / rear acceleration / deceleration detecting unit 42 is smaller than the predetermined value α1, and therefore the acceleration / deceleration correction gain calculated by the acceleration / deceleration correction gain calculating unit 43 is used. Even if Gα becomes “0” and the self-aligning torque SAT larger than “0” is output from the SAT estimation unit 41, the multiplication output output from the multiplier 44 becomes “0” and is output from the limiter 48. The steering assist force correction value As is also “0”, and the three-phase current command values Iaref, Ibref and Icref calculated by the dq-axis current command value calculation unit 25 are substantially “0”, so that the motor current The drive of the electric motor 5 by the control unit 26 is stopped.

  The occurrence of acceleration torque steer occurs not only at the time of starting but also at the time of acceleration with a large longitudinal acceleration / deceleration, and even at this acceleration, when the longitudinal acceleration / deceleration is a positive value representing acceleration as in the above-described starting, Similarly to the above, the steering assist force correction value As is calculated based on the self-aligning torque SAT estimated by the SAT estimation unit 41, and the steering assist current command value calculation unit 21 calculates the steering assist force correction value As. By correcting the steering assist current command value Iref, it is possible to cancel the reverse input torque due to torque steer and obtain good steering characteristics.

In addition, when the vehicle is running straight, for example, when the vehicle is in a braking state with a relatively large braking force, the braking force is caused by unbalanced braking force transmitted to the wheels and forces from various directions to the tire and suspension. During sudden braking with a large change and large deceleration, a phenomenon that causes vehicle deflection that disturbs the traveling path, that is, a vehicle flow during braking occurs.
In this case as well, when the vehicle is traveling straight ahead, the braking force applied to the wheels of the vehicle is increased when the braking force applied to the wheels of the vehicle is increased by depressing the brake pedal. Torque to twist the steering shaft 12 from the steered wheel 15 side of the steering mechanism 10 due to unbalanced braking force and force from various directions applied to the tire and suspension to cause the vehicle to unilaterally flow in one direction left and right. In particular, during steering, the steering force becomes a load, and the torque twisted from the steered wheel 15 side and the suspension side is transmitted to the steering shaft 12 via the coupling mechanism 14 such as a tie rod and the steering gear mechanism 13. Is done.

  However, the steering torque sensor 17 detects a torque corresponding to the force that twists the steering shaft 12 from the steered wheel 15 side, and drives the electric motor 5 based on this detected torque. A steering assist force is generated in a direction to reduce the torque transmitted from the side. In other words, the steering assist force of the electric power steering device promotes the vehicle single flow during braking.

  Therefore, when the front / rear acceleration / deceleration detecting unit 42 in the steering assist force correcting unit 23 detects a negative acceleration / deceleration αx exceeding a relatively large predetermined value −α2 representing the deceleration, and the vehicle one-way flow during braking occurs. The steering assist current command value calculation unit 21 detects the torsion torque transmitted from the steered wheel 15 side to the steering shaft 12 via the coupling mechanism 14 such as a tie rod and the steering gear mechanism 13 by the steering torque sensor 17. A steering assist current command value Iref that cancels the torsional torque is calculated.

  On the other hand, in the steering assist force correcting unit 23, the front / rear acceleration / deceleration detecting unit 42 detects a negative acceleration / deceleration αx exceeding a relatively large predetermined value −α2 representing the deceleration. , A negative acceleration / deceleration correction gain −Gα smaller than “0” is calculated, and this acceleration / deceleration correction gain −Gα is supplied to the multiplier 44, whereby the multiplication output of the multiplier 44 is − The sign of the self-aligning torque SAT is inverted as Gα × SAT.

  In this braking state, in order to suppress the vehicle single flow during braking, the steering state is maintained, and the absolute value | T | of the steering torque T detected by the steering torque sensor 17 is a relatively small value. The steering torque correction gain Gt calculated by the gain calculation unit 46 becomes a value in the vicinity of “1”, and this steering torque correction gain Gt is supplied to the multiplier 47, so that the multiplication output of the multiplier 44 −Gα × SAT. The multiplication output −Gα × Gt × SAT is multiplied by the steering torque correction gain Gt and supplied to the limiter 48. When the multiplication output −Gα × Gt × SAT is a value within a predetermined range by the limiter 48, the output is output as it is. When the maximum value is exceeded, it is suppressed to the positive and negative maximum values and is output to the adder 49 as the steering assist force correction value As.

Therefore, the steering assist force correction value As is subtracted from the steering assist current command value Iref calculated by the steering assist current command value calculation unit 21, and the steering according to the steering torque T generated by the electric motor 5 is performed. It is possible to suppress the vehicle fragment flow at the time of braking by suppressing the auxiliary force from acting in the direction of promoting the vehicle fragment flow at the time of braking.
Suppression of the vehicle flow at the time of braking that occurs at the time of sudden braking increases the steering assist force correction value As as the self-aligning torque SAT estimated by the SAT estimation unit 41 increases, and the front / rear acceleration / deceleration detection unit 42 The acceleration / deceleration correction gain Gα becomes a larger negative value as the absolute value of the negative value representing the deceleration of the detected longitudinal acceleration / deceleration αx becomes larger, and the steering assist force correction value As becomes larger, which occurs during sudden braking. As the vehicle piece flow increases, the steering assist force correction value As increases, the steering assistance current correction value Iref ′ obtained by correcting the steering assistance current command value Iref decreases, and the vehicle piece flow can be reliably suppressed.

  In addition, when the absolute value | T | of the steering torque T is close to zero, the steering torque correction gain Gt is set to “1”. The effect of suppressing the vehicle single flow can be maximized, and the steering assist force correction value As is suppressed to be small during steering when the steering wheel 11 is being steered. Steering performance change can be suppressed and optimal steering assist control can be performed in accordance with the state of occurrence of vehicle single flow during braking.

Next, a second embodiment of the present invention will be described with reference to FIGS.
In the second embodiment, instead of calculating the steering torque correction gain Gt according to the steering torque in the first embodiment described above, the steering angle of the steering device 10 is detected and the steering angle is adjusted. The correction gain is calculated.
That is, in the second embodiment, as shown in FIG. 7, in the configuration of FIG. 2 in the first embodiment described above, the absolute value converting circuit 45 for converting the steering torque T into an absolute value and the absolute value of the steering torque | The steering torque correction gain calculation means 46 for calculating the steering torque correction gain Gt based on T | is omitted, and instead of these, a steering angle detection unit 81 for detecting the steering angle φ of the steering shaft 12 and the steering angle detection unit Based on the absolute value conversion circuit 82 that converts the steering angle φ detected in 81 into an absolute value and the absolute value | φ | of the steering angle φ output from the absolute value conversion circuit 82, the calculation of the steering angle correction gain shown in FIG. A steering angle correction gain calculation unit 83 that calculates a steering angle correction gain Gφ with reference to the map is provided, and the steering angle correction gain Gφ calculated by the steering angle correction gain calculation unit 83 is supplied to the multiplier 48. Has the same configuration as FIG. 2 described above with the exception of bets, the same reference numerals are given to the corresponding parts in FIG. 2, and detailed description thereof will be omitted this.

  Here, in the steering angle correction gain calculation map, as shown in FIG. 8, the steering angle correction gain Gφ is set to “1” when the absolute value | φ | of the steering angle φ is between “0” and the predetermined value φ1. If the absolute value | φ | of the steering angle φ exceeds the predetermined value φ1, the absolute value | φ | of the steering angle φ decreases rapidly as the absolute value | φ | of the steering angle φ increases, and the steering angle absolute value | φ | After that, the characteristic line L4 is set so that the steering angle correction gain Gφ becomes “0” regardless of the increase of the steering angle absolute value | φ |.

  According to the second embodiment, since the SAT estimation unit 41 and the acceleration / deceleration correction gain calculation unit 43 have the same configuration as that of the first embodiment described above, the self-aligning torque estimated by the SAT estimation unit 41 As the SAT increases, the steering assist force correction value As increases. Similarly, as the absolute value of the acceleration / deceleration detected by the acceleration / deceleration detector 42 increases, the steering assist force correction value As increases. In addition to the effect of suppressing the torque steer and stabilizing the vehicle flow at the time of braking, the steering angle correction gain calculation unit 83 performs FIG. 8 according to the absolute value | φ | of the steering angle φ of the steering shaft 12. Since the steering angle correction gain Gφ is calculated with reference to the steering angle correction gain calculation map, it is accurately determined whether or not the vehicle is traveling straight on the basis of the steering angle φ. The optimum steering angle correction gain Gφ can be calculated depending on whether or not the vehicle is running straight, and the steering assist force correction value As is set optimally according to the running state of the vehicle. It is possible to perform good suppression control that eliminates the unstable behavior of the vehicle.

  In the above-described embodiment, the case where the control device 3 is configured by hardware has been described. However, the present invention is not limited to this, and the steering assist current command value calculation unit 21 and the motor rotation information are applied by applying a microcomputer. Calculation unit 22, steering assist force correction unit 23, command value compensation unit 24, dq axis current command value calculation unit 25, and subtracters 71 a to 71 c of motor current control unit 26, current control unit 72, pulse width modulation circuit 73 These functions can also be processed by software. As processing in this case, the microcomputer may execute the steering assist control processing shown in FIG.

  Here, as shown in FIG. 9, the steering assist control process is executed as a timer interrupt process every predetermined time (for example, 1 msec). First, in step S1, the steering torque sensor 17, the rotation angle sensor 18, the vehicle speed sensor are executed. 19. Read the detection values of various sensors such as the motor current detection unit 70, and then proceed to step S2 to steer with reference to the steering assist torque command value calculation map shown in FIG. After calculating the auxiliary torque command value Iref, the process proceeds to step S3.

In this step S3, the motor rotation angle θm is differentiated to calculate the motor angular velocity ωm, then the process proceeds to step S4, the motor angular speed ωm is differentiated to calculate the motor angular acceleration αm, and then the process proceeds to step S5. After performing the steering assist force correction value calculation process corresponding to the steering assist force correction unit 23, the process proceeds to step S6.
In step S6, similarly to the convergence compensation unit 51, the motor angular velocity ωm is multiplied by the compensation coefficient Kv set in accordance with the vehicle speed Vx to calculate the convergence compensation value Ic, and then the process proceeds to step S7.

  In step S7, similar to the inertia compensation unit 52, the inertia compensation value Ii is calculated based on the motor angular acceleration αm, and then the process proceeds to step S8 to calculate the steering assist current command value Iref in steps S5 to S7. The steering assist force correction value As, the convergence compensation value Ic, and the inertia compensation value Ii are added to calculate a post-compensation steering assist current command value Iref ″, and then d is added to the steering assist current command compensation value Iref ″ calculated in step S9. The dq-axis command value calculation process similar to that of the -q-axis current command value calculation unit 25 is executed to calculate the d-axis target current Idref and the q-axis target current Iqref, and then the process proceeds to step S10 and the two-phase / 3 A phase conversion process is performed to calculate motor current command values Iaref to Icref.

  Next, the process proceeds to step S11, the motor currents Ia to Ic are subtracted from the motor current command values Iaref to Icref to calculate the current deviations ΔIa to ΔIc, and then the process proceeds to step S12 and PI for the current deviations ΔIa to ΔIc. The control process is performed to calculate the voltage command values Varef to Vcref, and then the process proceeds to step S13, the duty ratio is calculated based on the calculated voltage command values Varef to Vcref, the pulse width modulation process is performed, and the inverter gate signal Then, the process proceeds to step S14, the formed inverter gate signal is output to the inverter 74, the steering assist control process is terminated, and the process returns to a predetermined main program.

  As shown in FIG. 10, the steering assist force correction value calculation process in step S5 is first described in step S21 based on the steering torque T, the steering assist current command value Iref, the motor angular velocity ωm, and the motor angular acceleration αm. The self-aligning torque SAT is calculated by performing the calculation of the equation (2), and then the process proceeds to step S22, the vehicle speed Vx is differentiated to calculate the longitudinal acceleration / deceleration αx, and then the process proceeds to step S23.

  In step S23, the acceleration / deceleration correction gain Gα is calculated based on the longitudinal acceleration / deceleration αx with reference to the above-described acceleration / deceleration correction gain calculation map of FIG. 5, and then the process proceeds to step S24 to determine the absolute value of the steering torque T. The value | T | is calculated, and then the process proceeds to step S25, where the steering torque correction gain Gt is determined by referring to the steering torque correction gain calculation map of FIG. 8 described above based on the absolute value | T | of the steering torque T. After the calculation, the process proceeds to step S26.

  In this step S26, the multiplication value Gα × Gt × SAT is calculated by multiplying the acceleration / deceleration correction gain Gα, the steering torque correction gain Gt, and the self-aligning torque SAT, and then the process proceeds to step S27 to calculate the calculated multiplication value Gα. A limiter process for limiting the value within the range of positive and negative maximum values to xGt * SAT is performed to calculate the steering assist force correction value As, and then the subroutine process ends, and the process proceeds to step S6 in FIG.

  9 and FIG. 10, the process of FIG. 9 corresponds to the steering assist force control means, among which the process of step S2 corresponds to the steering assist current command value calculation unit 21, and the processes of step S3 and step S4. Corresponds to the motor rotation information calculation unit 22, the processing of steps S5 and S8 and the processing of FIG. 10 correspond to the steering assist force correction unit 23, the processing of steps S6 to S8 corresponds to the command value compensation unit 24, The processes of S9 and S10 correspond to the dq-axis current command value calculation unit 25, and the processes of steps S11 to S14 and the inverter 74 correspond to the motor current control unit 26.

  The microcomputer performs the steering assist control process of FIG. 9 and the steering assist force correction value calculation process of FIG. 10 to optimize the torque steer that occurs during acceleration and the vehicle flow during deceleration that occurs during deceleration as in the above-described embodiment. An inverter control signal that generates a steering assist force that can be suppressed to a low speed can be formed. By supplying this inverter control signal to the inverter 74, the torque steer during acceleration that occurs during acceleration and deceleration and the vehicle flow during deceleration that occurs during deceleration are suppressed. Thus, optimal steering assist control can be performed.

  Further, in the steering assist force correction value calculation process corresponding to the steering assist force correction unit 23 in the second embodiment described above, as shown in FIG. 11, in the process of FIG. In step S31, the steering angle φ detected in 81 is read and the absolute value | φ | of the read steering angle φ is calculated, and step S25 is changed to step S31 described above based on the steering angle absolute value | φ |. Referring to the steering angle correction gain calculation map, step S32 is calculated to calculate the steering angle correction gain Gφ, step S26 is changed to step S33 to calculate a multiplication value of Gα × Gφ × SAT, and step S27 is further changed to Gα ×. Except for changing to step S34 for calculating the steering assist force correction value As by performing a limiter process on Gφ × SAT, the same process as in FIG. 10 may be performed.

Furthermore, in the first and second embodiments, the case where the self-aligning torque SAT is estimated based on the motor angular velocity ωm, the motor angular acceleration αm, the steering torque T, and the steering auxiliary current command value Iref has been described. However, the present invention is not limited to this. Instead of the steering assist current command value Iref, the motor currents Ia to Ic detected by the motor current detection unit 70 are three-phase / 2-phase converted to calculate the q-axis current Iq. The motor assist torque Tma calculated by performing the calculation of the following equation (3) based on the q-axis current Iq and the motor angular acceleration αm may be applied.
Tma = Kt · Iq−Jm · α (3)
Here, Kt is the torque constant of the motor, and Jm is the moment of inertia of the rotor portion of the motor.

  In addition, a torque sensor such as a magnetostrictive torque sensor is provided on the torque transmission shaft such as the output shaft of the electric motor 12 and the input / output shaft of the reduction gear 11, and the motor assist torque Tma detected by the torque sensor is applied. It may be.

  Furthermore, in the first and second embodiments, the case where the present invention is applied to a column-type electric power steering apparatus in which the electric motor 5 is connected to the steering shaft 12 via the speed reduction mechanism 16 has been described. The present invention is not limited to this, and a pinion type electric power steering device that connects an electric motor to the steering gear mechanism 13 via a speed reduction mechanism, or a rack type electric power that connects an electric motor to the rack shaft via a reduction gear. The present invention can also be applied to a steering device.

Furthermore, in the first and second embodiments, the case where the present invention is applied to a brushless motor has been described. However, the present invention is not limited to this, and when applied to a motor with a brush, FIG. As shown in FIG. 5, the following (based on the motor current detection value Im output from the motor current detection unit 70 in the angular velocity calculation unit 31 of the motor rotation information calculation unit 22 and the motor terminal voltage Vm output from the terminal voltage detection unit 90) 4) The motor angular velocity ωm is calculated by performing the calculation of equation (4), the dq axis current command value calculation unit 25 is omitted, and the compensated torque command value Iref ″ is directly supplied to the motor current control unit 26. What is necessary is just to change the current control part 26 to the one subtraction part 71, the current control part 72, the pulse width modulation circuit 73, and the inverter 74 to the H bridge circuit 91, respectively.
ωm = (Vm−Im · Rm) / K ₀ (4)
Here, Rm is the motor winding resistance, and K ₀ is the electromotive force constant of the motor.

1 is a diagram illustrating a schematic configuration of an electric power steering apparatus according to a first embodiment of the present invention. It is a block diagram which shows the specific structure of a control apparatus. It is a characteristic diagram which shows the steering assist torque command value calculation map which shows the relationship with the steering assist torque command value which uses vehicle speed as a parameter. It is a schematic diagram with which it uses for description of the self-aligning torque. It is a characteristic diagram which shows the acceleration / deceleration correction gain calculation map showing the relationship between the longitudinal acceleration / deceleration and the acceleration / deceleration correction gain. FIG. 6 is a characteristic diagram showing a steering torque correction gain calculation map representing a relationship between an absolute value of steering torque and a steering torque correction gain. It is a block diagram of a control device showing a 2nd embodiment of the present invention. It is a characteristic diagram which shows the steering angle correction gain calculation map showing the relationship between the steering angle and steering angle correction gain which can be applied to 2nd Embodiment. It is a flowchart which shows an example of the execution steering assistance control processing procedure with a microcomputer. 10 is a flowchart illustrating an example of a steering assist force correction value calculation processing procedure in FIG. 9. 10 is a flowchart showing another example in the steering assist force correction value calculation processing procedure of FIG. 9. It is a block diagram which shows embodiment at the time of applying a motor with a brush.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Battery, 3 ... Control apparatus, 5 ... Electric motor, 10 ... Steering mechanism, 11 ... Steering wheel, 12 ... Steering shaft, 13 ... Steering gear, 14 ... Connection mechanism, 15 ... Steering wheel, 16 ... Deceleration mechanism, 17 DESCRIPTION OF SYMBOLS ... Steering torque sensor, 18 ... Rotation angle sensor, 19 ... Vehicle speed sensor, 21 ... Steering auxiliary current command value calculating part, 22 ... Motor rotation information calculating part, 23 ... Steering auxiliary force correction part, 24 ... Command value compensating part, 25 ... dq-axis current command value calculation unit, 26 ... motor current control unit, 30 ... electric angle conversion unit, 31 ... angular velocity calculation unit, 32 ... angular velocity calculation unit, 41 ... self-aligning torque (SAT) estimation unit, 42: Front / rear acceleration / deceleration detection unit, 43 ... Acceleration / deceleration correction gain calculation unit, 44 ... Multiplier, 45 ... Absolute value conversion circuit, 46 ... Steering torque correction gain calculation unit, 47 ... Multiplier, 8 ... limiter, 49 ... adder, 51 ... convergence compensation unit, 52 ... inertia compensation unit, 53, 54 ... adder, 61 ... d-axis current command value calculation unit, 62 ... induced voltage model calculation unit, 63 ... q Axis current command value calculation unit, 64 ... 2 phase / 3 phase conversion unit, 70 ... Motor current detection unit, 71a to 71c ... Subtraction unit, 72 ... Current control unit, 73 ... Pulse width modulation unit, 74 ... Inverter, 81 ... Steering angle detection unit, 82 ... absolute value circuit, 83 ... steering angle correction gain calculation unit

Claims (7)

Steering torque detection means for detecting steering torque input to the steering mechanism for turning the steered wheels, an electric motor for generating steering assist torque to be applied to the steering mechanism, and at least steering torque detected by the steering torque detection means An electric power steering device comprising a steering assist force control means for calculating a current command value based on the driving control of the electric motor,
A self-aligning torque estimating means for estimating a self-aligning torque input to the steering mechanism from the steered wheel side; a front-rear acceleration / deceleration detecting means for detecting a vehicle longitudinal acceleration / deceleration; Generated by the electric motor so as to suppress the unstable behavior of the vehicle that occurs during acceleration / deceleration based on the self-aligning torque estimated by the self-aligning torque estimating means and the acceleration / deceleration detected by the front / rear acceleration / deceleration detecting means. A steering assist force correcting means for correcting the steering assist force is provided.
The electric power steering apparatus according to claim 1, wherein the steering assist force correcting means is configured to increase a correction amount for correcting the steering assist force as the self-aligning torque increases . 2. The electric power steering apparatus according to claim 1, wherein the steering assist force correcting unit is configured to increase a correction amount for correcting the steering assist force as the front / rear acceleration / deceleration increases . The electric power steering apparatus according to claim 1 or 2, wherein the steering assist force correcting means is configured to correct the steering assist force by correcting the current command value . The electric power steering apparatus according to claim 3 , wherein the steering assist force correcting unit is configured to set a correction amount that increases the current command value when the vehicle is accelerated . The steering assist force correction means, during deceleration of the vehicle, the electric power steering apparatus according to claim 3 or 4, wherein the current command value is configured to set the small Kunar correction amount. The steering assist force correction means, to any one of claims 1 to 5, characterized by being composed of the correction amount so that varied according to the detected steering torque by the steering torque detection means The electric power steering apparatus as described. Steering angle detection means for detecting the steering angle of the steering mechanism is provided, and the steering assist force correction means is configured to change the correction amount according to the steering angle detected by the steering angle detection means . The electric power steering apparatus according to any one of claims 1 to 5, wherein

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