JP2014088138A - Electric power steering device - Google Patents

Abstract

Provided is a technique capable of suppressing noise / abnormal noise and vibration due to feedback responsiveness adjustment while suppressing output of an assist torque contrary to a driver's steering intention from an electric motor.
A target current calculation unit that sets a target current to be supplied to an electric motor based on a steering torque, a motor drive unit that drives the electric motor by supplying current, and a target current calculation unit. A feedback processing unit 42 that performs feedback control so that the target current set by and the actual current supplied to the electric motor 110 match, and a gain correction unit 43 that changes the feedback gain of the feedback processing unit 42 according to the vehicle speed; When the relationship between the steering torque and the actual current is a predetermined relationship, an output prohibition determination unit that suppresses the current supplied to the electric motor 110 by the motor drive unit 32, and a predetermined relationship according to the vehicle speed And an index setting unit for setting.
[Selection] Figure 4

Description

  The present invention relates to an electric power steering apparatus.

In recent years, there has been proposed an electric power steering device that includes an electric motor in a steering system of a vehicle and assists a driver's steering force with the power of the electric motor.
In such an electric power steering device, for example, in order to prevent an assist torque that is against the driver's steering intention from being output from the electric motor based on the magnitude and direction of the steering torque input from the steering wheel. It has been proposed to have the following functions. That is, an output prohibition region for prohibiting the operation of the electric motor is set on a two-dimensional coordinate or the like according to the steering torque and the actual current supplied to the electric motor. If the duration belonging to the region is equal to or longer than a predetermined time, the current supplied to the electric motor is set to zero (for example, see Patent Document 1).

  In the electric power steering device, the steering torque applied to the steering wheel of the vehicle by the driver's operation is detected, and the target current to the electric motor necessary for obtaining the assist torque according to the detected steering torque is set. Is done. Then, the electric motor is feedback-driven based on the deviation between the target current and the actual current so that the set target current and the actual current that actually flows through the electric motor match.

JP 2000-190861 A

In a system that feedback-drives based on the deviation between the target current and the actual current of the electric motor, it is desirable that the responsiveness in this system is high in order to cause the assist torque generated by the electric motor to quickly follow the steering torque. However, when the responsiveness of the system is high, the current to be supplied to the electric motor becomes large when the steering wheel is turned to the limit in the stop state, so-called stationary, and the ripple fluctuation range becomes large. May occur or noise or abnormal noise may occur. For this reason, it is conceivable that the responsiveness in the system is lowered only under the situation where the stationary operation is performed, but in such a case, the steering torque and the actual current are likely to enter the above-described output prohibition region, and the driver's steering intention is reduced. Despite the fact that the assist torque is output from the electric motor, the current supplied to the electric motor may be set to zero if the assist torque that is against the driver's steering intention is output from the electric motor. There is.
The present invention provides an electric power steering device capable of suppressing noise / abnormal noise and vibration due to feedback response adjustment while suppressing output of an assist torque against the driver's steering intention from the electric motor. The purpose is to do.

  For this purpose, the present invention provides an electric motor that applies a steering assist force to a steering wheel provided in a vehicle, and a target current setting that sets a target current to be supplied to the electric motor based on a steering torque of the steering wheel. Feedback, so that the target current set by the target current setting means and the actual current supplied to the electric motor coincide with each other, the drive means for driving the electric motor by supplying current to the electric motor The relationship between the steering torque and the actual current is a predetermined relationship, the feedback control unit performing the control, the changing unit changing the feedback gain of the feedback control unit according to the vehicle speed that is the moving speed of the vehicle. Suppression means for suppressing current supplied to the electric motor by the driving means in a certain case, and Setting means for setting the predetermined relationship according to the speed of an electric power steering apparatus comprising: a.

Here, the changing means may make the feedback gain smaller when the vehicle speed is low than when the vehicle speed is high.
In addition, the suppression means is configured to supply the electric motor when the steering torque and the actual current belong to a predetermined area formed based on the range of the steering torque and the range of the actual current. It is preferable to suppress the supplied current.
Further, the setting means may make the predetermined region smaller when the vehicle speed is low than when the vehicle speed is high.

The changing means maximizes the feedback gain when the vehicle speed is equal to or higher than a predetermined first vehicle speed, and the setting means when the vehicle speed is equal to or higher than the first vehicle speed. It is advisable to make the predetermined area the smallest.
The changing means minimizes the feedback gain when the vehicle speed is equal to or lower than a predetermined second vehicle speed, and the setting means is configured to reduce the feedback gain when the vehicle speed is equal to or lower than the second vehicle speed. The predetermined area may be maximized.

  According to the present invention, it is possible to suppress noise / abnormal noise and vibration due to feedback responsiveness adjustment while suppressing output of assist torque against the driver's steering intention from the electric motor.

It is a figure showing the schematic structure of the electric power steering device concerning an embodiment. It is a schematic block diagram of a control apparatus. It is a schematic block diagram of a target current calculation part. It is a schematic block diagram of a control part. It is a figure which shows the correlation of a vehicle speed and a feedback gain. It is a schematic block diagram of a prohibition signal output part. It is a figure which illustrates the parameter | index which an parameter | index setting part sets. It is a flowchart which shows the procedure of the output prohibition determination process which an output prohibition determination part performs. It is a figure which illustrates the relationship between steering torque and an actual current.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a diagram illustrating a schematic configuration of an electric power steering apparatus 100 according to an embodiment.
Electric power steering device 100 (hereinafter, also simply referred to as “steering device 100”) is a steering device for arbitrarily changing the traveling direction of a vehicle, and in this embodiment, an automobile as an example of the vehicle. The structure applied to is illustrated.

  The steering apparatus 100 includes a wheel-like steering wheel 101 that is operated by a driver to change the traveling direction of the automobile, and a steering shaft 102 that is provided integrally with the steering wheel 101. . The steering device 100 includes an upper connecting shaft 103 connected to the steering shaft 102 via a universal joint 103a, and a lower connecting shaft 108 connected to the upper connecting shaft 103 via a universal joint 103b. . The lower connecting shaft 108 rotates in conjunction with the rotation of the steering wheel 101.

  Steering device 100 includes tie rods 104 connected to left and right front wheels 150 as rolling wheels, and rack shaft 105 connected to tie rods 104. Further, the steering device 100 includes a pinion 106 a that constitutes a rack and pinion mechanism together with rack teeth 105 a formed on the rack shaft 105. The pinion 106 a is formed at the lower end portion of the pinion shaft 106.

  The steering device 100 also has a steering gear box 107 that houses the pinion shaft 106. The pinion shaft 106 is connected to the lower connection shaft 108 via a torsion bar (not shown) in the steering gear box 107. A torque sensor 109 that detects the steering torque T of the steering wheel 101 based on the relative angle between the lower connecting shaft 108 and the pinion shaft 106 is provided inside the steering gear box 107.

  The steering device 100 includes an electric motor 110 supported by the steering gear box 107, and a speed reducing mechanism 111 that decelerates the driving force of the electric motor 110 and transmits it to the pinion shaft 106. Electric motor 110 according to the present embodiment is a three-phase brushless motor. The speed reduction mechanism 111 includes, for example, a worm wheel (not shown) fixed to the pinion shaft 106, a worm gear (not shown) fixed to the output shaft of the electric motor 110, and the like.

  In addition, the steering device 100 includes a control device 10 that controls the operation of the electric motor 110. The control device 10 receives the output value of the torque sensor 109 described above, the output value of the vehicle speed sensor 170 that detects the vehicle speed Vc, which is the moving speed of the automobile, and the like.

  The steering device 100 configured as described above detects the steering torque T applied to the steering wheel 101 by the torque sensor 109, drives the electric motor 110 in accordance with the detected torque, and generates torque generated by the electric motor 110. Is transmitted to the pinion shaft 106. Thereby, the torque generated by the electric motor 110 assists the driver's steering force applied to the steering wheel 101.

Next, the control device 10 will be described.
FIG. 2 is a schematic configuration diagram of the control device 10.
The control device 10 is an arithmetic and logic circuit composed of a CPU, ROM, RAM, backup RAM, and the like.
The control device 10 includes a torque signal Td obtained by converting the steering torque T detected by the torque sensor 109 described above into an output signal, and a vehicle speed signal obtained by converting the vehicle speed Vc detected by the vehicle speed sensor 170 into an output signal. v or the like is input.
Then, the control device 10 calculates a target auxiliary torque based on the torque signal Td, the vehicle speed signal v, and the like, and sets a target current setting that calculates a target current It necessary for the electric motor 110 to supply the target auxiliary torque. A target current calculation unit 20 as an example of a unit and a control unit 30 that performs feedback control based on the target current It calculated by the target current calculation unit 20 are included.

Next, the target current calculation unit 20 will be described in detail.
FIG. 3 is a schematic configuration diagram of the target current calculation unit 20.
The target current calculation unit 20 includes a base current calculation unit 21 that calculates a base current that serves as a reference for setting the target current, an inertia compensation current calculation unit 22 that calculates a current for canceling the inertia moment of the electric motor 110, and And a damper compensation current calculation unit 23 for calculating a current for limiting the rotation of the motor. The target current calculation unit 20 includes a target current determination unit 25 that determines the target current It based on values calculated by the base current calculation unit 21, the inertia compensation current calculation unit 22, and the damper compensation current calculation unit 23. ing.

  The target current calculation unit 20 receives a torque signal Td, a vehicle speed signal v, a rotation speed signal Nms obtained by converting the rotation speed Nm of the electric motor 110 into an output signal, and the like. The rotational speed signal Nms is, for example, a sensor configured to detect a rotational position of a rotor (rotor) of the electric motor 110 that is a three-phase brushless motor (for example, a rotor configured by a resolver, a rotary encoder, or the like that detects the rotational position of the rotor). It can be exemplified that the value obtained by differentiating the rotation angle of the electric motor 110 detected by the position detection circuit) is converted into an output signal.

  The base current calculation unit 21 calculates the base current Ib based on the torque signal Ts obtained by phase compensation of the torque signal Td by the phase compensation unit 26, the vehicle speed signal v from the vehicle speed sensor 170, and the like. That is, the base current calculation unit 21 calculates the base current Ib according to the phase-compensated steering torque T and the vehicle speed Vc. The base current calculation unit 21 is, for example, a phase-compensated steering torque T (torque signal Ts), vehicle speed Vc (vehicle speed signal v), and base current that are created in advance based on empirical rules and stored in the ROM. The base current Ib is calculated by substituting the steering torque T (torque signal Ts) and the vehicle speed Vc (vehicle speed signal v) into the map showing the correspondence with Ib.

  The inertia compensation current calculation unit 22 calculates an inertia compensation current Is for canceling out the moment of inertia of the electric motor 110 and the system based on the torque signal Td and the vehicle speed signal v. That is, the inertia compensation current calculation unit 22 calculates the inertia compensation current Is according to the steering torque T (torque signal Td) and the vehicle speed Vc (vehicle speed signal v). Note that the inertia compensation current calculation unit 22 generates, for example, the steering torque T (torque signal Td), the vehicle speed Vc (vehicle speed signal v), and the inertia compensation current Is, which are previously created based on empirical rules and stored in the ROM. The inertia compensation current Is is calculated by substituting the steering torque T (torque signal Td) and the vehicle speed Vc (vehicle speed signal v) into the map showing the correspondence between the two.

  The damper compensation current calculation unit 23 calculates a damper compensation current Id that limits the rotation of the electric motor 110 based on the torque signal Td, the vehicle speed signal v, and the rotation speed signal Nms of the electric motor 110. That is, the damper compensation current calculation unit 23 calculates the damper compensation current Id corresponding to the steering torque T (torque signal Td), the vehicle speed Vc (vehicle speed signal v), and the rotational speed Nm (rotational speed signal Nms) of the electric motor 110. calculate. For example, the damper compensation current calculation unit 23 is prepared based on an empirical rule and stored in the ROM in advance, such as steering torque T (torque signal Td), vehicle speed Vc (vehicle speed signal v), and rotation speed Nm (rotation). Damper by substituting steering torque T (torque signal Td), vehicle speed Vc (vehicle speed signal v), and rotational speed Nm (rotational speed signal Nms) into a map showing the correspondence between speed signal Nms) and damper compensation current Id. A compensation current Id is calculated.

  The target current determination unit 25 includes the base current Ib calculated by the base current calculation unit 21, the inertia compensation current Is calculated by the inertia compensation current calculation unit 22, and the damper compensation calculated by the damper compensation current calculation unit 23. A target current It is determined based on the current Id. The target current determination unit 25, for example, previously creates a compensation current Ic obtained by adding the inertia compensation current Is to the base current Ib and subtracting the damper compensation current Id based on an empirical rule, and stores it in the ROM. The target current It is calculated by substituting it into a map showing the correspondence between the compensation current Ic and the target current It.

Next, the control unit 30 will be described in detail.
FIG. 4 is a schematic configuration diagram of the control unit 30.
The control unit 30 detects a motor drive control unit 31 that controls the operation of the electric motor 110, a motor drive unit 32 as an example of a drive unit that drives the electric motor 110, and an actual current Im that actually flows through the electric motor 110. A motor current detection unit 33 that performs the operation, and a prohibition signal output unit 34 that outputs an output prohibition signal for prohibiting the motor drive unit 32 from driving the electric motor 110.

  The motor drive control unit 31 is based on a deviation between the target current It finally determined by the target current calculation unit 20 and the actual current Im supplied to the electric motor 110 detected by the motor current detection unit 33. A feedback (F / B) control unit 40 that performs feedback control, and a PWM signal generation unit 60 that generates a PWM (pulse width modulation) signal for PWM driving the electric motor 110.

The feedback control unit 40 includes a deviation calculating unit 41 for obtaining a deviation between the target current It finally determined by the target current calculating unit 20 and the actual current Im detected by the motor current detecting unit 33, and the deviation is A feedback (F / B) processing unit 42 as an example of feedback control means for performing feedback processing so as to be zero is provided.
The feedback (F / B) processing unit 42 performs feedback control so that the target current It and the actual current Im coincide with each other. For example, the feedback gain G is applied to the deviation calculated by the deviation calculating unit 41. Multiply

The feedback control unit 40 includes a gain correction unit 43 that corrects the feedback gain G of the feedback (F / B) processing unit 42. The gain correction unit 43 corrects the feedback gain G according to the vehicle speed Vc. The gain correction unit 43 functions as an example of a changing unit that changes the feedback gain G in accordance with the vehicle speed Vc.
FIG. 5 is a diagram showing a correlation between the vehicle speed Vc and the feedback gain G.
For example, the gain correction unit 43 assigns the feedback gain G by substituting the vehicle speed Vc into a map that is created in advance and stored in the ROM and that shows the correspondence between the vehicle speed Vc and the feedback gain G as shown in FIG. calculate. In the map shown in FIG. 5, when the vehicle speed Vc is equal to or higher than the first vehicle speed V1, a value obtained by multiplying the feedback gain G by 1 is the corrected feedback gain G, and the vehicle speed Vc is the second vehicle speed V2 (V2 <V V1) or less, the feedback gain G is correlated with α (α <1) so that the corrected feedback gain G is obtained. Further, the feedback gain G is correlated so as to gradually increase from α × G to 1 × G from the second vehicle speed V2 to the first vehicle speed V1.

In other words, when the vehicle speed Vc is smaller than the first vehicle speed V1, the gain correction unit 43 corrects the value to be smaller than a predetermined feedback gain G, and until the second vehicle speed V2, the vehicle speed Vc is corrected. As feedback becomes smaller, the feedback gain G is corrected so as to gradually become smaller. When the vehicle speed Vc is equal to or lower than the second vehicle speed V2, a value obtained by multiplying a predetermined feedback gain G by α is set as a corrected feedback gain G.
It can be exemplified that the first vehicle speed V1 is 30 km / h, the second vehicle speed V2 is 10 km / h, and α is 0.3.

  The PWM signal generation unit 60 generates a PWM signal for driving the electric motor 110 by PWM (pulse width modulation) based on the output value from the feedback control unit 40, and outputs the generated PWM signal 60a.

The motor drive unit 32 is a so-called inverter, and includes, for example, six independent transistors (FETs) as switching elements. Three of the six transistors are a positive line of a power source, an electric coil of each phase, The other three transistors are connected to the electric coil of each phase and the negative side (ground) line of the power source. Then, the driving of the electric motor 110 is controlled by driving the gates of two transistors selected from the six and switching the transistors.
The motor current detection unit 33 detects the value of the actual current Im flowing through the electric motor 110 from the voltage generated at both ends of the shunt resistor connected to the motor drive unit 32.

Next, the prohibition signal output unit 34 will be described in detail.
FIG. 6 is a schematic configuration diagram of the prohibition signal output unit 34.
The prohibition signal output unit 34 determines whether or not to prohibit the output of the electric motor 110 based on the steering torque T of the steering wheel 101 and the actual current Im of the electric motor 110. An output prohibition determination unit 341 that outputs an output prohibition signal to the drive unit 32, and an index setting unit 342 as an example of a setting unit that sets an index when the output prohibition determination unit 341 determines according to the vehicle speed Vc. Have. The output prohibition determination unit 341 functions as an example of a suppression unit that suppresses the current supplied to the electric motor 110 by the motor driving unit 32.

  The output prohibition determination unit 341 is configured to prohibit the motor drive unit 32 from supplying current to the electric motor 110 when the relationship between the steering torque T and the actual current Im is a predetermined correspondence. Output prohibition signal. More specifically, the output prohibition determination unit 341 includes a torque signal Td, an output signal from the motor current detection unit 33, information indicating the direction of current from the target current calculation unit 20 (such as a sign of the target current It), and the like. Based on these, the steering torque T and the actual current Im of the electric motor 110 are grasped, and the index setting unit 342 is set so that the grasped steering torque T and the actual current Im output an output prohibition signal. If it belongs to the area continuously for a predetermined time, an output prohibition signal is output to the motor drive unit 32. Then, the motor drive unit 32 that has acquired the output prohibition signal turns off all the transistors to set the current supplied to the electric motor 110 to zero.

The index setting unit 342 has a plurality of indices, and selects and sets an optimum index from the plurality of indices according to the vehicle speed Vc.
FIG. 7 is a diagram illustrating an index set by the index setting unit 342.
In the index shown in FIG. 7, an output prohibition region for prohibiting the output of the electric motor 110 is set on a two-dimensional coordinate determined from the steering torque T and the actual current Im.
The index setting unit 342 has a plurality of indices. The index shown in FIG. 7A is an index set when the vehicle speed Vc is equal to or higher than the first vehicle speed V1, and the index shown in FIG. 7B is the second vehicle speed when the vehicle speed Vc is described above. This is an index set when V2 or less. As shown in FIGS. 7A and 7B, the output prohibition region in the index when the vehicle speed Vc is equal to or lower than the second vehicle speed V2 is the output in the index when the vehicle speed Vc is equal to or higher than the first vehicle speed V1. It is narrower than the prohibited area. That is, the steering torque T and the actual current Im that belong in the output prohibition region in the index when the vehicle speed Vc is equal to or higher than the first vehicle speed V1 do not belong in the output prohibition region in the index when the vehicle speed Vc is equal to or lower than the second vehicle speed V2. An area exists.

  In FIG. 7, as an index set by the index setting unit 342, an index when the vehicle speed Vc is equal to or higher than the first vehicle speed V1 and an index when the vehicle speed Vc is equal to or lower than the second vehicle speed V2 are illustrated. However, the index from the second vehicle speed V2 to the first vehicle speed V1 is that the output prohibited area in the index is between the output prohibited area shown in FIG. 7 (b) and the output prohibited area shown in FIG. 7 (a). Is set. That is, it is determined that the region from the output prohibition region in the index at the second vehicle speed V2 or less to the output prohibition region in the index at the first vehicle speed V1 or more gradually increases.

  In the prohibition signal output unit 34 configured in this way, when the steering torque T and the actual current Im grasped by the output prohibition determination unit 341 correspond to the index set by the index setting unit 342 (output prohibition region in this index) When the output prohibition signal is output to the motor drive unit 32, the electric motor 110 is prevented from assisting the driver's steering force so as to be contrary to the driver's steering intention. For example, in the case where an excessive current is supplied to the electric motor 110 due to an abnormality in a device such as the target current calculation unit 20, the driving of the electric motor 110 is stopped.

Hereinafter, output prohibition determination processing performed by the output prohibition determination unit 341 will be described using a flowchart.
FIG. 8 is a flowchart illustrating a procedure of output prohibition determination processing performed by the output prohibition determination unit 341. The output prohibition determination unit 341 executes the output prohibition determination process, for example, periodically (for example, every 1 ms).

The output prohibition determination unit 341 first grasps the actual current Im and the steering torque T of the electric motor 110 at the present time (step (hereinafter simply referred to as “S”) 801). Then, it is grasped which index is set by the index setting unit 342 among the plurality of indices (S802).
Then, the output prohibition determination unit 341 determines whether or not the relationship between the actual current Im and the steering torque T grasped in S801 belongs to a predetermined output prohibition region in the index grasped in S802 ( S803). If it belongs to the output prohibition region (YES in S803), whether or not the actual current Im and the steering torque T continue to belong to the output prohibition region determined to belong in S803 for a predetermined time or more. Is discriminated (S804). If it continues for the specified time or longer (YES in S804), an output prohibition signal is output to the motor drive unit 32 (S805).
On the other hand, if it does not belong to the output prohibition region (NO in S803) and if it has not continued for the specified time (NO in S804), the execution of this process is terminated without outputting the output prohibition signal.

  In the steering device 100 configured as described above, when the vehicle speed Vc is small, feedback control is performed using the feedback gain G corrected to be smaller than the predetermined feedback gain G. When the vehicle speed Vc is low, the ripple fluctuation width of the current flowing through the electric motor becomes small. In particular, even when the steering wheel is turned to the limit in a stopped state such as when entering a garage or parking, feedback control is performed using a feedback gain G having a small value, so that the ripple fluctuation range is small. As a result, it is possible to suppress the occurrence of large vibrations, noise, or abnormal noise in the steering device 100 that performs feedback control. In particular, the smaller the vehicle speed Vc, such as when entering a garage or when parking, the quieter the interior of an automobile equipped with the steering device 100, the vibration and sound of the steering device 100 will resonate inside the vehicle. According to the steering device 100 according to the embodiment, it is possible to suppress vibrations and sounds reverberating in the vehicle.

However, if feedback control is performed using the feedback gain G corrected so as to be smaller than the predetermined feedback gain G, the responsiveness decreases, and the target current It set according to the steering torque T is reduced. Thus, the actual current Im becomes difficult to follow.
FIG. 9 is a diagram illustrating the relationship between the steering torque T and the actual current Im. FIG. 9A is a diagram showing the relationship between the steering torque T and the actual current Im when feedback control is performed using a predetermined feedback gain G, and FIG. It is a figure which shows the relationship between the steering torque T at the time of performing feedback control using the feedback gain G correct | amended by multiplying the feedback gain G which was added, and the actual electric current Im.
As shown in FIG. 9, by reducing the feedback gain G, the responsiveness decreases, and the actual current Im in the steering wheel 101 increasing direction with respect to the steering torque T and the actual current in the switching back direction of the steering wheel 101 are reduced. The difference from Im increases.

  On the other hand, according to the steering device 100 according to the present embodiment, as illustrated in FIG. 7A and FIG. 7B, the output prohibited area varies depending on the vehicle speed Vc, and the vehicle speed Vc is the first. When the vehicle speed Vc is equal to or lower than the vehicle speed V2, in other words, when the feedback gain G is corrected to α times smaller, the output prohibition region in the index is when the vehicle speed Vc is equal to or higher than the first vehicle speed V1, in other words, the feedback gain G is used as it is. It is narrower than the output forbidden area in the indicator. Therefore, by reducing the feedback gain G, the response to the steering torque T is lowered so that the difference between the actual current Im in the steering wheel 101 increasing direction and the actual current Im in the switching back direction is increased. However, it becomes difficult for the steering torque T and the actual current Im to belong to the output prohibited area for a specified time. As a result, it is determined that an assist torque that is contrary to the driver's steering intention is output from the electric motor even though the assist torque in accordance with the driver's steering intention is output from the electric motor. It can be suppressed that no current is supplied to the power source.

  On the other hand, when the vehicle speed Vc is equal to or higher than the first vehicle speed V1, the output prohibition region is wider than when the vehicle speed Vc is less than the first vehicle speed V1, and thus assist torque that is contrary to the driver's steering intention is electrically driven. In the case of output from the motor, the current supply to the electric motor can be quickly made zero. Therefore, when the vehicle speed Vc is high, for example, when a situation occurs in which an excessive current is supplied to the electric motor 110 due to an abnormality in a device such as the target current calculation unit 20, the electric motor 110 is quickly driven. Can be stopped. As a result, it is possible to suppress an automobile from causing an accident due to the behavior that is contrary to the driver's steering intention when the vehicle speed Vc is high.

  As described above, according to the steering device 100 according to the present embodiment, it is possible to suppress the output of the assist torque against the driver's steering intention from the electric motor, while reducing noise and noise due to a decrease in feedback responsiveness. Sound and vibration can be suppressed. In particular, when the vehicle speed Vc at which it is dangerous to exhibit a behavior contrary to the driver's steering intention is high, the drive of the electric motor 110 is quickly stopped if an excessive current is supplied to the electric motor 110. In addition, when the vehicle speed Vc at which the sound and vibration are likely to resonate in the vehicle is small, the sound and vibration due to the current ripple fluctuation range can be suppressed.

DESCRIPTION OF SYMBOLS 10 ... Control apparatus, 20 ... Target electric current calculation part, 30 ... Control part, 34 ... Prohibition signal output part, 40 ... Feedback control part, 42 ... Feedback (F / B) processing part, 43 ... Gain correction part,
DESCRIPTION OF SYMBOLS 100 ... Electric power steering apparatus, 110 ... Electric motor, 341 ... Output prohibition determination part, 342 ... Index setting part

Claims (6)

An electric motor for providing a steering assist force to a steering wheel provided in the vehicle;
Target current setting means for setting a target current to be supplied to the electric motor based on a steering torque of the steering wheel;
Drive means for driving the electric motor by supplying current to the electric motor;
Feedback control means for performing feedback control so that the target current set by the target current setting means matches the actual current supplied to the electric motor;
Changing means for changing a feedback gain of the feedback control means according to a vehicle speed which is a moving speed of the vehicle;
Suppression means for suppressing current supplied to the electric motor by the drive means when the relationship between the steering torque and the actual current is a predetermined relation;
Setting means for setting the predetermined relationship according to the vehicle speed;
An electric power steering apparatus comprising:   2. The electric power steering apparatus according to claim 1, wherein the changing unit reduces the feedback gain when the vehicle speed is low than when the vehicle speed is high.   The suppression means supplies the electric motor to the electric motor when the steering torque and the actual current belong to a predetermined region formed based on the range of the steering torque and the range of the actual current. The electric power steering apparatus according to claim 1, wherein current is suppressed.   The electric power steering apparatus according to any one of claims 1 to 3, wherein the setting means reduces the predetermined region when the vehicle speed is low than when the vehicle speed is high. The changing means maximizes the feedback gain when the vehicle speed is equal to or higher than a predetermined first vehicle speed,
5. The electric power steering apparatus according to claim 3, wherein the setting unit minimizes the predetermined area when the vehicle speed is equal to or higher than the first vehicle speed. 6. The changing means minimizes the feedback gain when the vehicle speed is equal to or lower than a predetermined second vehicle speed,
6. The electric power steering apparatus according to claim 3, wherein when the vehicle speed is equal to or lower than the second vehicle speed, the setting unit makes the predetermined region the largest. 7. .

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