JP5050542B2 - Electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power steering device for securing steering performance in ordinary steering, while reducing limit cycle vibration and noise when keeping steering without impairing a steering feeling, by controlling validation/invalidation of feedforward control and feedback control by a parameter, based on a rotating speed of a detected motor or a rotating speed of a steering wheel. <P>SOLUTION: This electric power steering device is provided with a motor rotation detecting means for detecting the rotating speed of the motor, and a parameter control means for changing the parameter of a feedforward control means and a feedback control means, and controls the motor by changing the parameter of the feedforward control means and the feedback control means in response to the motor rotating speed. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a control device for an electric power steering device in which a steering assist force by a motor is applied to a steering device of a vehicle, and more particularly to an electric power steering device with a good steering feeling with less steering vibration and noise.

  Various control units are mounted on the vehicle, and the control unit is also provided in the electric power steering device that biases the vehicle steering device with the auxiliary load by the rotational force of the motor. The motor is driven by this control unit. The driving force of the motor is biased to the steering shaft or the rack shaft by a transmission mechanism such as a gear or a belt via a speed reducer.

  Here, the general configuration of the electric power steering apparatus will be described with reference to FIG. Coupled to the tie rod 6. The column shaft 2 is provided with a torque sensor 10 that detects the steering torque of the steering handle 1, and a motor 20 that assists the steering force of the steering handle 1 is coupled to the column shaft 2 via the reduction gear 3. ing. A power is supplied from the battery 14 to the control unit 30 that controls the power steering device, and an ignition signal is input through the ignition key 11. The control unit 30 detects the steering torque T and the vehicle speed detected by the torque sensor 10. An assist command steering assist command value I is calculated based on the vehicle speed V detected by the sensor 12, and a current supplied to the motor 20 is controlled based on the calculated steering assist command value I.

  The control unit 30 is mainly composed of a CPU (including MPU and MCU). FIG. 11 shows general functions executed by a program inside the CPU.

  The function and operation of the control unit 30 will be described with reference to FIG. 11. The torque T detected by the torque sensor 10 and the vehicle speed V detected by the vehicle speed sensor 12 are input to the assist map 301 and the steering assist command value is calculated. Calculated. Further, the compensation value calculated by the compensation value control unit 310, for example, the convergence calculated by the convergence control unit 311, the inertia compensation value obtained by the inertia compensation unit 312, and obtained by the self-aligning torque (SAT) estimation unit 313. The compensation value obtained by adding the obtained SAT value by the addition units 315 and 316 is added to the steering assist command value by the addition unit 302 to determine the torque command value Tref. Based on the torque command value Tref, the current command value calculation unit 303 determines the current command value Iref and inputs it to the subtraction unit 304.

  On the other hand, the motor current Im supplied to the motor 20 is detected by the current detector 307, and a deviation ΔI = (Iref−Im) from the current command value Iref is calculated.

  The deviation ΔI is input to the proportional term 321 that is the proportional gain Kp and the integral term 322 that is the integral gain Ki that constitute the PI control unit 320. The voltage command value Vref is output by addition.

  The voltage command value Vref is input to the PWM control unit 305 and outputs a PWM signal to the inverter circuit 306, whereby the motor current Im is supplied to the motor 20 based on the PWM signal.

  Here, the gain Gi related to the proportional integral of the PI control unit 320 is expressed by an equation as shown in Equation 1.

つまり、偏差ΔＩが小さい値であっても、ゲインＧｉが無限大になるために、ハンドル保舵時やゆっくりした操舵時にも電圧指令値Ｖｒｅｆは大きな値として出力され、以下のような問題が発生する。

That is, even if the deviation ΔI is a small value, the gain Gi becomes infinite, so that the voltage command value Vref is output as a large value even during steering of the steering wheel or during slow steering, causing the following problems. To do.

  Recent electric power steering devices have increased capacity (increased current), but a digital filter or the like of a control device mainly composed of a CPU cannot fully cope with the increased current. For example, since the resolution remains 10 bits, the resolution becomes relatively coarse as the current increases. That is, if the current feedback control is configured digitally, it is necessary to A / D convert the motor current Im and digitize it. However, the digitized motor current Im includes a quantization error due to A / D conversion. Therefore, the motor current Im cannot be controlled with an accuracy higher than the resolution of A / D conversion, and if feedback control is performed with a signal including a quantization error, the output current causes limit cycle vibration. As a result, vibration and noise occur in a steering state (steering state) in which the steering handle 1 is fixed. Further, such limit cycle vibration is amplified by a feedback gain that makes the gain when the deviation ΔI at the time of steering or slow steering small is infinite, resulting in vibration and noise of the steering handle 1 to the driver. There is a problem that causes discomfort.

  In addition to the above, in the current control of the control unit 30, integral control (I control), proportional integral control (PI control) and proportional integral derivative control (PID control) are generally used. However, in the current control including the integral term, since the gain is infinite in the steady state as described above, the vibration and noise are felt when the steering state is the steady state of the electric power steering apparatus or when the steering is slowly performed. As a result, there is a problem that the driver's steering wheel is uncomfortable.

  As means for solving such a problem, for example, a control device for an electric power steering apparatus disclosed in Japanese Patent Application Laid-Open No. 2001-315657 (Patent Document 1) calculates a disturbance voltage acting on a motor from a current value with respect to an applied voltage, and this disturbance. A voltage that compensates for the voltage is applied to the motor so that there is no pulsation of current due to disturbance and a comfortable steering feeling can be obtained. That is, a control device for an electric power steering device that assists a steering torque generated in a steering wheel shaft by a driver with a motor, and includes target current determining means for determining a target current value to be passed through the motor, a target current value and a current motor current A first current controller that outputs a first signal based on a difference from a current value, and outputs a second signal corresponding to a disturbance voltage generated in the motor from a voltage applied to the motor and a current value of the motor. Disturbance voltage calculating means for adding the first signal and the second signal and outputting a voltage reference signal corresponding to the voltage to be applied to the motor.

  In addition, the electric power steering apparatus disclosed in Japanese Patent Laid-Open No. 2003-170855 (Patent Document 2) raises the input resolution by raising the input of a digital filter having a zero point to a power, and the change in input is smaller than a predetermined value. By using an input value that passes through a predetermined pulse transfer function, a change in the input signal is suppressed. As a result, noise when the signal is differentiated is also suppressed, and control sound can be reduced and smooth steering feeling can be obtained. In other words, the motor that provides the steering assist force to the steering mechanism is controlled based on the current control value calculated from the steering assist command value calculated by the calculation means based on the steering torque and the vehicle speed and the current value of the motor. In the electric power steering apparatus, the current control function for controlling the motor current based on the detected steering torque includes a plurality of LSB filters, and the digital filter having a zero point among the LSB filters increases the input by a power of two. The power input is set, and when the absolute value of the difference between the current value of the power input and the previous sampling is larger than the predetermined value, the power input is used for the input of the digital filter having a zero, and the current power input When the absolute value of the difference between the value and the value before one sampling is less than the predetermined value, The filter function is provided to use the value through the can multiply inputting a predetermined pulse transfer function.

  In addition, the electric power steering apparatus disclosed in Japanese Patent No. 3705545 (Patent Document 3) increases the feedforward control gain of the feedforward control unit when the vehicle speed is high, and decreases the gain when the vehicle speed is low. Similarly, the gain of the feedback control is increased when the vehicle speed is fast, and is decreased when the vehicle speed is slow. This suppresses the occurrence of overshoots and natural vibrations that are likely to occur at low vehicle speeds and increases stability, and at high vehicle speeds, it improves high-speed response and improves operability, converging vibrations. It improves the performance and enables stable operation. That is, a steering torque detecting means for detecting a steering torque of the steering system, a motor for giving a steering assist force to the steering system, a motor current detecting means for detecting a driving current of the motor, and a steering torque detected by the steering torque detecting means. Target current setting means for setting a target current for driving the motor based on the feedback control, and feedback control for performing feedback control according to a deviation between the target current set by the target current setting means and the motor drive current detected by the motor current detection means And a feedforward control unit that performs feedforward control according to the target current, the gain of the feedforward control of the feedforward control unit is increased as the vehicle speed increases.

In addition, since the electric power steering apparatus disclosed in Japanese Patent Application Laid-Open No. 2006-27412 (Patent Document 4) uses a current controller with a finite steady-state gain, there is a deviation during steering of the steering wheel or during slow steering. Since the output torque due to is not increased, the steering feeling is improved without feeling vibration or noise through the steering wheel. That is, an output value of the torque sensor includes a motor that applies a steering assist force to the steering system of the vehicle, a torque sensor that detects a steering force that acts on the steering wheel, and a current detector that detects a current of the motor. In the electric power steering apparatus that feedback-controls the motor based on the output of the current controller that receives the deviation between the current command value Iref determined based on the current and the motor current Im, the gain of the current controller is finite. To be.
JP 2001-315657 A JP 2003-170855 A Japanese Patent No. 3705545 JP 2006-27412 A

  However, since the devices of Patent Documents 1 to 4 described above all perform feedback control (integration control) of current, there is a problem that current limit cycle vibration cannot be eliminated. Further, although vibration and noise during steering of the steering wheel are improved, there is a problem that vibration and noise of the steering wheel are generated. Furthermore, the conventional system has a problem that it cannot fully cope with the increase in capacity and current.

  The present invention has been made under the circumstances described above, and an object of the present invention is to determine whether the feedforward control and the feedback control are valid / invalid based on the detected number of rotations of the motor or the rotational speed of the handle. By controlling by switching, electric power steering that reduces limit cycle vibration and noise during steering without compromising normal steering feeling, can handle high currents, and ensures steering performance. To provide an apparatus.

The present invention includes a feedback control unit that performs feedback control based on a deviation between a current command value determined based on a steering torque and a motor current, and a feedforward control unit that performs feedforward control based on the current command value. The present invention relates to an electric power steering apparatus that controls a motor by applying a steering assist force to a steering system, and the object of the present invention is to detect the motor rotation speed or the steering wheel rotation speed, and to detect it by the steering detection means. And a comparison switching means for comparing the feedforward control means and the feedback control means to enable / disable by comparing the motor rotation speed or the handle rotational speed with a predetermined value, and the motor rotation by the comparison switching means. When the number or the handle rotation speed is determined to be equal to or greater than the threshold 1, The feedforward control unit is disabled, the feedback control unit is enabled, and the feed rate control unit determines that the feed rate control unit determines that the motor rotation speed or the handle rotation speed is less than or equal to a threshold value 2 (<threshold value 1). This is achieved by enabling the forward control means and disabling the feedback control means. The comparison switching means makes the motor rotation speed or the handle rotation speed smaller than the threshold value 1 and more than the threshold value 2. Is determined to be greater than the threshold value 3 by enabling the feedforward control means and the feedback control means, or by the comparison switching means. The feedforward control means is invalidated Both enable the feedback control means, and if the comparison switching means determines that the motor rotation speed or the handle rotation speed is smaller than the threshold 3, enable the feedforward control means. This is achieved more effectively by disabling the feedback control means .

The present invention also provides feedback control means for performing feedback control based on a deviation between a current command value determined based on a steering torque and a motor current, and feedforward control for performing feedforward control based on the current command value. The above-mentioned object of the present invention is to provide a steering detection means for detecting the motor rotation speed or the steering wheel rotation speed, and the steering detection means. An output adjustment unit that continuously changes the validity / invalidity of the feedforward control means and the feedback control means based on the motor rotation speed or the handle rotation speed detected in step S, and the motor rotation speed or the handle When it is determined that the rotation speed is equal to or greater than the threshold value 1, the output adjustment unit When the feedforward control means is continuously disabled and the feedback control means is continuously enabled, and the motor rotation speed or the handle rotation speed is determined to be equal to or less than a threshold value 2 (<threshold value 1), This is achieved by continuously enabling the feedforward control means and continuously disabling the feedback control means by the output adjustment unit .

The object of the present invention is to provide the feedforward control means and the feedforward control means when the motor rotational speed or the handle rotational speed is determined to be smaller than the threshold value 1 and larger than the threshold value 2. This is achieved more effectively by enabling the feedback control means continuously .

  According to the electric power steering device of the present invention, based on the detected rotation speed of the motor or the rotation speed of the handle, when the rotation speed of the motor or the rotation speed of the handle is close to zero, only the feedforward control is enabled. Since the feedforward control and the feedback control are enabled / disabled by parameters or switching so that only the feedback control is enabled when the motor speed or the rotation speed of the handle is large. Reduces limit cycle vibration and noise during steering without compromising steering feeling and reduces the cost of components by eliminating the need for high-performance and expensive hardware associated with high currents be able to.

  The electric power steering apparatus according to the present invention is in the state of steering or is steered based on the number of rotations of the motor or the rotation speed of the handle detected by the steering detection means (motor rotation number detection means or handle rotation speed detection means). It is determined whether it is in a state. Based on the determination result, validity / invalidity of the feedforward control means and the feedback control means is controlled by the parameter control means or the switching means. In other words, if it is determined that the steering handle is in the steered state (the motor speed is close to zero or the handle speed is close to zero) based on the motor speed or the handle speed, the feed Enable forward control and disable feedback control. Further, when it is determined that the steering handle is in a steering state and the motor rotation speed or the rotation speed of the steering wheel is sufficiently high, the feedforward control is disabled and the feedback control is enabled. . In addition, when it is determined that the steering handle is in a steering state and the rotational speed of the motor or the rotational speed of the steering wheel is gradually increased, the feedforward control is gradually disabled and the feedback control is performed. By gradually enabling it, the limit cycle vibration and noise at the time of steering are reduced to improve the steering feeling of the steering wheel, and the steering performance at the time of normal steering is also ensured.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration example of the present invention, and shows an example in which the steering detection means is a motor rotation number detection means.

  The electric power steering apparatus of the present invention includes a feedforward control means 51 that performs feedforward control for improving responsiveness based on the current command value Iref, a motor command Im detected by the current command value Iref and the current detection unit 38, and Feedback control means 52 for performing feedback control based on a deviation ΔI = (Iref−Im), a rotation speed detection means 53 for detecting a motor rotation speed rs from an input signal of a rotation angle detection section of the motor, and the rotation speed detection Parameter control means 50 is provided for controlling the validity / invalidity of the feedforward control and the feedback control by changing the parameters of the feedforward control means 51 and the feedback control means 52 according to the motor rotation speed rs from the means 53.

  Further, the output from the feedforward control means 51 whose validity / invalidity is controlled by the parameters set by the parameter control means 50 and the output from the feedback control means 52 are added by the adder 55 and then the motor current. Im is input to the motor 20. The motor current Im is detected by the current detection unit 38 and input to the subtraction unit 54, and a deviation ΔI between the current command value Iref and the motor current Im is input to the feedback control unit 52.

  In such a configuration, an example of the operation will be described with reference to the flowchart of FIG.

  First, the rotational speed detection means 53 always detects the rotational speed of the motor 20, and inputs the detected motor rotational speed rs to the parameter control means 50 (step S10). Next, the parameter control means 50 compares the predetermined upper limit threshold value 1 with hysteresis and the motor rotational speed rs (step S11), and determines that the motor rotational speed rs is equal to or higher than the upper limit threshold value 1 Assuming that sufficient steering is being performed, the parameter control means 50 changes the parameters of the control system to enable feedback control (step S15) and disables feedforward control (step S16). . In step S15, the feedback control is enabled, and only the feedback control is performed as in the shaded area AR1 in FIG. 3 (step S19).

  On the other hand, when it is determined in step S11 that the motor rotational speed rs is smaller than the upper limit threshold 1, a predetermined lower limit threshold 2 with hysteresis is compared with the motor rotational speed rs (step S12). When it is determined that the motor rotation speed rs is equal to or lower than the lower limit threshold value 2, the following parameter control is performed (step S14). That is, assuming that the steering wheel is in the steering holding state, the parameter control means 50 invalidates the feedback control by changing the parameter (step S17) and validates the feedforward control (step S18). In step S18, the feedforward control is enabled, and only the feedforward control is performed as in the shaded area AR2 in FIG. 3 (step S20).

  If it is determined in step S12 that the motor rotation speed rs is greater than the lower limit threshold value 2, the motor rotation speed rs is within the upper and lower limit threshold values 1 and 2, and feed that is normal control is performed. Control is performed in a state where both forward control and feedback control are valid (step S21).

  FIG. 3 shows an example of parameter control by the parameter control means 50 when the motor rotational speed rs changes as shown by a solid line. The motor rotational speed rs is larger than the threshold 2 and smaller than the threshold 1 until the time t1. Therefore, both feedforward control and feedback control are effective. Since the motor rotation speed rs is equal to or greater than the threshold value 1 at time points t1 to t2, feedback control is enabled and feedforward control is disabled.

  The feedforward control and the feedback control are both effective at the time points t2 to t3. However, since the motor rotation speed rs is equal to or less than the threshold value 2 at the time points t3 to t4, the feedforward control is enabled and the feedback control is disabled. The state in which forward control and feedback control are effective is shown.

  Next, an embodiment in which the present invention is mounted on a control unit of an electric power steering apparatus and the motor 20 for applying a steering assist force is controlled will be described with reference to the block diagram of FIG.

  The steering torque T from the torque sensor is input to the steering assist command value calculation unit 100 and the differential compensation unit 101. The vehicle speed V from the vehicle speed sensor is input to the gain setting unit 102, the steering assist command value calculation unit 100, the convergence control unit 104, and the inertia compensation unit 105. Further, the steering speed, the steering angle, and the estimated SAT value from the steering angle sensor, the steering speed sensor, and the SAT (self-aligning torque) estimation means are input to the gain setting unit 102.

  The steering assist command value Ia calculated by the steering assist command value calculation unit 100 based on the steering torque T is input to the phase compensation unit 103 and is input to the addition unit 60 as the steering assist command value Ib to stabilize the operation, and is subjected to differential compensation. The steering torque dh whose responsiveness has been improved in the unit 101 is also input to the adding unit 60. The outputs of the convergence control unit 104 and the inertia compensation unit 105 are input to the subtraction unit 63, and the subtraction processing result sk is input to the addition unit 60. In the addition unit 60, the steering assist command value Ib, the steering torque dh, and the subtraction processing result sk. Are added. The steering assist command value Ic, which is the addition result of the adding unit 60, is input to the feedforward control unit 51 and the subtracting unit 61 to improve the response, and the output Ig of the feedforward control unit 51 is output from the switching unit 502. The signal is input to the contact a. The motor current Id detected by the current detection unit 38 and the gain value gs calculated by the gain setting unit 102 are added by the adding unit 62, and the added current value Ie is output, and the steering assist command value is output by the subtracting unit 61. Subtraction processing is performed from Ic. The deviation If obtained by the subtraction unit 61 is input to the feedback control unit 52, and the output Ih of the feedback control unit 52 is input to the contact b of the switching unit 502. The output Ig of the feedforward control unit 51 and the output Ih of the feedback control unit 52 are subjected to addition processing, and the voltage command value Va subjected to the addition processing is input to the PWM control unit 112. The voltage command value Vb subjected to PWM control is applied to the motor 20 via the inverter circuit 111.

  The rotation angle detection unit 110 connected to the motor 20 includes a resolver, a rotary encoder, and the like. The detected rotation angle θ is input to the angular velocity calculation unit 108, and the calculated angular velocity ω is the motor rotation speed. Input to the detection means 53, the angular acceleration calculation unit 107, and the convergence control unit 104. The motor rotation number detection unit 53 detects the motor rotation number rs based on the input angular velocity ω, and the motor rotation number rs is input to the comparison switching unit 501. The comparison switching unit 501 compares the motor rotation speed rs with the threshold value 1 and the threshold value 2 and outputs a switching signal Sw. The angular velocity ω input to the angular acceleration calculation unit 107 is input to the inertia compensation unit 105 as the angular acceleration α.

  The inertia compensator 105 assists the force equivalent generated by the inertia of the motor, and prevents the inertia or control response from deteriorating. The convergence control unit 104 applies a brake to the movement of the steering wheel to improve the yaw convergence.

  In such a configuration, the feedforward control unit 51 and the feedback control unit 52 are switched by the comparison switching unit 501 and the switching unit 502 in accordance with the rotation speed of the motor 20. That is, when the motor rotation speed rs is equal to or greater than the threshold value 1, the comparison switching means 501 turns on only the contact b of the switching unit 502 by the switching signal Sw, and when the motor rotation speed rs is equal to or less than the threshold value 2, the comparison switching means 501 switches. Only the contact a of the switching unit 502 is turned on by the signal Sw. When the motor rotation speed rs is smaller than the threshold value 1 and larger than the threshold value 2, the contacts a and b are turned on and controlled.

  Next, another embodiment in which the present invention is mounted on an electric power steering apparatus will be described with reference to the block diagram of FIG. 5 corresponding to FIG.

  In the embodiment of FIG. 4, the feedforward control means 51 and the feedback control means 52 are on / off controlled by the switching unit 502 by the switching signal Sw. However, in the embodiment of FIG. In this configuration example, the output adjustment unit 504 gradually (continuously) changes the validity / invalidity of the feedforward control and the feedback control as the motor rotational speed rs increases or decreases.

  According to this example, as shown in FIG. 6, the output Ig from the feedforward control means 51 is gradually invalidated (decreased) and the output Ih of the feedback control means 52 is gradually increased as the motor rotational speed rs increases. To be effective (large). Also by this, it is possible to perform only feedback control when the threshold is 1 or more, perform only feedforward control when the threshold is 2 or less, and perform both feedforward control and feedback control between the thresholds 1 and 2. In this example, an output adjustment unit 504 is provided, and the output synthesis ratio of the output Ig of the feedforward control unit 51 and the output Ih of the feedback control unit is variable. However, the feedforward control unit 51 and the feedback control unit 52 include a motor. It is also possible to output the outputs Ig and Ih with the characteristics shown in FIG. 6 by inputting the rotation speed rs and changing the internal parameters.

  In the above example, the upper and lower thresholds 1 and 2 are used to determine whether the vehicle is in the steered state or in the state where the steering wheel is being steered. It is also possible to control the validity / invalidity of the feedforward control and the feedback control with three threshold values 3. An example will be described with reference to the flowchart of FIG. 7 and the characteristic example of FIG.

  In this example, the control is performed only with the threshold value 3, and when the motor rotational speed rs is equal to or higher than the threshold value 3, the feedforward control is invalidated and the feedback control is validated as shown in FIG. When it becomes smaller (time t10 to t11 in FIG. 8), the feedback control is invalidated and the feedforward control is validated.

  That is, the rotation speed detection means 53 detects the motor rotation speed detection rs and inputs it to the parameter control means 50 (step S30), and the parameter control means 50 compares the threshold value 3 with the motor rotation speed rs (step S31). . When it is determined that the motor rotation speed rs is equal to or greater than the threshold 3, it is determined that sufficient steering is being performed, and the feedback control is validated (step S34) and the feedforward control is invalidated (step S35). Then, the feedback control becomes valid as shown in FIG. 8 until time t10, and only the feedback control is performed (step S38). If it is determined in step S31 that the motor rotation speed rs is smaller than the threshold value 3 (time point 10 in FIG. 8), the parameter control means 50 disables the feedback control, assuming that the steering wheel is in the steering holding state. At the same time (step S36), feed-forward control is validated (step S37). And feedforward control becomes effective as shown to the time t10-t11 of FIG. 8, and only feedforward control is performed (step S39).

  In the above-described example, the steering detection unit is controlled as the motor rotation number detection unit 53. However, the steering detection unit is the handle rotation speed detection unit, and the parameter control unit similarly performs the control based on the detected rotation speed of the handle. An example of performing the control will be described with reference to FIG.

  FIG. 9 is a block diagram showing another configuration example of the present invention. Moreover, it is a figure shown corresponding to FIG. 1, and attaches | subjects the same code | symbol to the same part, and abbreviate | omits description.

  The electric power steering apparatus according to the present invention includes a handle rotation speed detection means 63 for detecting a handle rotation speed ss from an input signal from a steering angle sensor, and a feedforward control means based on the handle rotation speed ss from the handle rotation speed detection means 63. 51 and a parameter control means 50 for controlling the validity / invalidity of the feedforward control and the feedback control by changing the parameters of the feedback control means 52.

  In such a configuration, the control method performed based on the handle rotational speed ss is detected by the parameter control means 50 as in the method of comparing and determining the motor rotational speed rs and the threshold value in the operation examples in FIGS. Feedforward control and feedback control are performed based on the determination result of the steering wheel rotation speed ss and the threshold value. Similarly, in the example shown in FIG. 6, the same effect can be obtained by replacing the motor rotational speed rs and the handle rotational speed ss. For example, the parameter control means 50 gradually disables (decreases) the output from the feedforward control means 51 and gradually enables (increases) the output of the feedback control means 52 as the detected handle rotational speed ss increases. ), It is also possible to output with characteristics as shown in FIG.

  In addition, although the case where the motor rotation speed rs or the handle rotation speed ss gradually increases has been described as an embodiment, the motor rotation speed rs or the handle rotation speed ss may gradually decrease. However, the same effect can be obtained by setting the parameter control means 50 with a parameter for gradually enabling the feedforward control and gradually disabling the feedback control as in the case of increasing. In addition, the parameters for simultaneously enabling / disabling the feedforward control and the feedback control by comparing the upper and lower thresholds 1 and 2 or one threshold 3 with the motor rotational speed rs or the steering wheel rotational speed ss have been described. Since the feedforward control means 51 and the feedback control means 52 can set parameters separately, a time factor may be included. For example, when the motor rotation speed rs or the steering wheel rotation speed ss rises and exceeds the threshold value 1 or 3, the parameter may be set so that the feedforward control is enabled first and then the feedback control is disabled. Alternatively, when the motor rotation speed or the handle rotation speed ss decreases and exceeds the threshold value 2, the parameter may be set so that the feedforward is invalidated first and the feedback control is validated thereafter. Further, although the resolver and the rotary encoder have been described as an example of the motor rotation angle detection unit 110, the motor rotation speed rs may be calculated using the motor angular velocity calculated from the back electromotive force estimated value.

  Furthermore, although the electric power steering device has been described as an example in the above description, the present invention can also be applied to a motor control device that controls a motor based on a current command value.

It is a block diagram which shows the structural example of the control system which concerns on this invention. It is a flowchart which shows the operation example of this invention. It is a figure for demonstrating the operation example of this invention. It is a block diagram which shows the structural example of the electric power steering apparatus which concerns on this invention. It is a block diagram which shows the other structural example of the electric power steering apparatus which concerns on this invention. It is a figure for demonstrating the operation example of this invention. It is a flowchart which shows the operation example of the electric power steering apparatus which concerns on this invention. It is a figure for demonstrating the operation example of this invention. It is a block diagram which shows another structural example of the control system which concerns on this invention. It is a figure which shows schematic structure of a general electric power steering apparatus. It is a block diagram which shows the structural example of the conventional control system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering handle 2 Column shaft 3 Reduction gear 10 Torque sensor 20 Motor 30 Control unit 38 Current detection part 50 Parameter control means 51 Feed forward control means 52 Feedback control means 53 Motor rotation speed detection means 63 Handle rotation speed detection means 100 Steering assistance Command value calculation unit 101 Differential compensation unit 104 Convergence control unit 105 Inertia compensation unit 108 Angular velocity calculation unit 110 Rotation angle detection unit 501 Comparison switching unit 502 Switching unit 504 Output adjustment unit

Claims (5)

The motor is controlled by feedback control means for performing feedback control based on a deviation between the current command value determined based on the steering torque and the motor current, and a feedforward control means for performing feedforward control based on the current command value. In the electric power steering device that applies a steering assist force to the steering system,
Steering detection means for detecting the motor rotation speed or steering wheel rotation speed, and comparing the motor rotation speed or the steering wheel rotation speed detected by the steering detection means with a predetermined value, the feedforward control means and the feedback control. A comparison switching means for switching the validity / invalidity of the means,
When the motor switching speed or the handle rotational speed is determined to be greater than or equal to a threshold value 1 by the comparison switching unit, the feedforward control unit is disabled and the feedback control unit is enabled,
Enabling the feedforward control means and disabling the feedback control means when the comparison switching means determines that the motor rotational speed or the handle rotational speed is equal to or less than a threshold value 2 (<threshold value 1). An electric power steering device. When the comparison switching means determines that the motor rotational speed or the handle rotational speed is smaller than the threshold value 1 and larger than the threshold value 2, the feedforward control means and the feedback control means are enabled. The electric power steering apparatus according to claim 1. When the comparison switching means determines that the motor rotation speed or the steering wheel rotation speed is greater than the threshold 3, the feedforward control means is disabled and the feedback control means is enabled,
When the comparison switching means determines that the motor rotation speed or the handle rotation speed is smaller than the threshold value 3, the feedforward control means is enabled and the feedback control means is disabled. Item 4. The electric power steering device according to Item 1. The motor is controlled by feedback control means for performing feedback control based on a deviation between the current command value determined based on the steering torque and the motor current, and a feedforward control means for performing feedforward control based on the current command value. In the electric power steering device that applies a steering assist force to the steering system,
Steering detection means for detecting the motor rotation speed or steering wheel rotation speed, and validity / invalidity of the feedforward control means and the feedback control means based on the motor rotation speed or the steering wheel rotation speed detected by the steering detection means An output adjustment unit that continuously changes
When the motor rotation speed or the handle rotation speed is determined to be equal to or greater than the threshold value 1, the output adjustment unit continuously disables the feedforward control unit and enables the feedback control unit continuously. ,
When the motor rotation speed or the steering wheel rotation speed is determined to be equal to or less than a threshold value 2 (<threshold value 1), the output adjustment unit continuously enables the feedforward control unit, and the feedback control unit An electric power steering device characterized by being continuously disabled. When it is determined that the motor rotational speed or the handle rotational speed is smaller than the threshold value 1 and larger than the threshold value 2, the output adjustment unit continuously causes the feedforward control means and the feedback control means to The electric power steering apparatus according to claim 4, wherein the electric power steering apparatus is enabled.

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