Motor control devices, electric actuator products and electric power steering devices

Abstract

This motor control device comprises: a current command value calculation unit (41) that calculates a current command value for driving a motor; a current value detection unit (48) that detects current flowing in the motor; a current control unit (52) that outputs a first voltage command value in accordance with the deviation between a current detection value, which is the detection value of the current detected by the current value detection unit (48), and the current command value; a voltage disturbance suppression unit (53) that calculates a second voltage command value by adding the output of a delay element (55) to the first voltage command value, and that inputs the second voltage command value into the delay element (55); and a driving circuit (47) for driving the motor on the basis of the second voltage command value.

Description

[Technical field]

[0001] The present invention relates to a motor control device, an electric actuator product, and an electric power steering device. [Background technology]

[0002] The following Patent Document 1 describes a technology that estimates the back electromotive force based on a back electromotive force constant and a motor rotation speed, and compensates for the back electromotive force by adding a correction value that offsets the back electromotive force to a voltage command value (hereinafter, this may be referred to as "feedforward-type back electromotive force compensation"). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-175834 A Summary of the Invention [Problem to be solved by the invention]

[0004] Feedforward-type back EMF compensation has the problem of low robustness against disturbance factors such as variations due to individual differences in the motor used, temperature changes, and changes in physical properties due to aging. An object of the present invention is to provide a motor control device that has improved robustness against disturbance factors such as variations due to individual differences in the motors used, temperature changes, and changes in physical properties due to aging. [Means for solving the problem]

[0005] In order to achieve the above object, a motor control device according to one aspect of the present invention includes a current command value calculation unit that calculates a current command value for driving a motor, a current value detection unit that detects a current flowing through the motor, and a current detection value that is a detection value of the current detected by the current value detection unit, and outputs a first voltage command value in accordance with a deviation between the current command value and the current detection value. It has the characteristics of proportional control, integral control and differential control for deviation. A current control unit; It is placed after the current control section and responds to the input signal input in the previous control period of the current control section. Control period of current control section minutes Given a delay of The input signal is output as a delayed signal in the current control period of the current control section. The output of the delay element is The first voltage command value The voltage disturbance suppression unit calculates a second voltage command value by adding the voltage disturbance suppression unit and inputs the second voltage command value to a delay element, and a drive circuit drives the motor based on the second voltage command value.

[0006] According to another aspect of the present invention, there is provided an electric actuator product including the motor control device described above and a motor controlled by the motor control device. According to yet another aspect of the present invention, there is provided an electric power steering device including the motor control device described above and a motor controlled by the motor control device, the electric power steering device applying a steering assist force to a steering system of a vehicle by the motor. Effect of the Invention

[0007] According to the present invention, it is possible to provide a motor control device that has improved robustness against disturbance factors such as variations due to individual differences in the motors used, temperature changes, and changes in physical properties due to aging. [Brief description of the drawings]

[0008] [Figure 1] 1 is a configuration diagram showing an overview of an example of an electric power steering device according to an embodiment; [Diagram 2] 2 is a block diagram showing an example of a functional configuration of a steering assist function by a controller shown in FIG. 1. [Diagram 3] FIG. 2 is a block diagram showing a first example of a system in which a motor is driven based on a current command value, expressed using a transfer function. [Figure 4] 4(a) and (b) are Bode plots of an example of frequency characteristics when the numerator of the common term of the transfer function of the system of FIG. 3 is set to 1. [Diagram 5] 4(a) and (b) are Bode plots of an example of the control filter 52 of FIG. 3. [Figure 6] 4(a) and (b) are Bode plots of an example of a transfer function in which the transfer functions of delay element 56 and filter 54 are removed from the numerator of the common term of the transfer function of the system of FIG. [Figure 7] 13A and 13B are Bode diagrams of an example of a transfer function of a component in which a disturbance voltage Δv affects a motor current i. [Figure 8] 13(a) and 13(b) are Bode plots showing simulation results of a comparative example. [Figure 9] 13(a) and 13(b) are Bode plots showing simulation results of the embodiment. [Figure 10] FIG. 11 is a block diagram showing a second example of a system in which a motor is driven based on a current command value, expressed by a transfer function. [Figure 11] FIG. 11 is a block diagram showing a third example of a system in which a motor is driven based on a current command value, expressed by a transfer function. [Figure 12] 1 is a configuration diagram showing an overview of an example of a linear motion table device using a motor control device of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the drawings. The embodiments of the present invention described below are merely examples of devices and methods for embodying the technical idea of ​​the present invention, and the technical idea of ​​the present invention does not limit the configuration, arrangement, etc. of the components to those described below. The technical idea of ​​the present invention can be modified in various ways within the technical scope defined by the claims.

[0010] (composition) 1 is a schematic diagram showing an example of an electric power steering device according to an embodiment. A steering shaft (steering shaft, handle shaft) 2 of a steering wheel (steering handle) 1 is connected to steered wheels 8L, 8R via reduction gears (worm gears) 3 constituting a reduction mechanism, universal joints 4a and 4b, a pinion rack mechanism 5, and tie rods 6a and 6b, and further via hub units 7a and 7b.

[0011] The pinion rack mechanism 5 has a pinion 5a connected to a pinion shaft to which steering force is transmitted from the universal joint 4b, and a rack 5b that meshes with this pinion 5a. The rotational motion transmitted to the pinion 5a is converted into linear motion in the vehicle width direction by the rack 5b. The steering shaft 2 is provided with a torque sensor 10 for detecting a steering torque Th. The steering shaft 2 is also provided with a steering angle sensor 14 for detecting a steering angle θh of the steering wheel 1.

[0012] In addition, a motor 20 that assists the steering force of the steering wheel 1 is connected to the steering shaft 2 via a reduction gear 3. A controller 30 that controls an electric power steering (EPS) device is supplied with power from a battery 13 and receives an ignition key signal via an ignition (IGN) key 11. The means for applying the steering assist force is not limited to a motor, and various types of actuators can be used.

[0013] The controller 30 is an electronic control unit (ECU: Electronic Control Unit) that calculates a current command value of an assist control command based on the steering torque Th detected by the torque sensor 10, the vehicle speed Vh detected by the vehicle speed sensor 12, and the steering angle θh detected by the steering angle sensor 14, and controls the current supplied to the motor 20 using a voltage control command value Vref that has been subjected to compensation, etc., for the current command value. Incidentally, the steering angle sensor 14 is not essential, and the steering angle θh may be calculated by adding the torsion angle of the torsion bar of the torque sensor 10 to the rotation angle obtained from a rotation angle sensor that detects the rotation angle of the rotating shaft of the motor 20. Also, instead of the steering angle θh, the turning angle of the steered wheels 8L, 8R may be used. For example, the turning angle may be detected by detecting the displacement amount of the rack 5b.

[0014] The controller 30 may be, for example, a computer including a processor and peripheral components such as a storage device, etc. The processor may be, for example, a CPU (Central Processing Unit) or an MPU (Micro-Processing Unit). The storage device may include any one of a semiconductor storage device, a magnetic storage device, and an optical storage device. The storage device may include a register, a cache memory, a memory such as a ROM (Read Only Memory) and a RAM (Random Access Memory) used as a main memory device. The functions of the controller 30 described below are realized, for example, by the processor of the controller 30 executing a computer program stored in a storage device.

[0015] The controller 30 may be formed of dedicated hardware for executing each of the information processes described below. For example, the controller 30 may include a functional logic circuit configured in a general-purpose semiconductor integrated circuit. For example, the controller 30 may include a programmable logic device (PLD) such as a field programmable gate array (FPGA).

[0016] Next, an example of the functional configuration of the steering assist function by the controller 30 will be described with reference to FIG. The steering torque Th and the vehicle speed Vh are input to a current command value calculation unit 41 that calculates a current command value Iref0. The current command value calculation unit 41 calculates the current command value Iref0, which is a control target value of the current supplied to the motor 20, based on the input steering torque Th and vehicle speed Vh, using an assist map or the like.

[0017] The adder 42A adds the compensation signal CM from the compensation signal generation unit 44 to the current command value Iref0 to calculate the current command value Iref=Iref0+CM, and inputs the current command value Iref to the current limiting unit 43. The addition of the compensation signal CM compensates for the characteristics of the steering system, improving the convergence and inertia characteristics, etc. The compensation signal generation unit 44 calculates the compensation signal CM by adding the convergence 44-1, inertia 44-2, and self-aligning torque (SAT) 44-3 using adders 44-4 and 44-5. A current command value Irefm, the maximum current of which has been limited by a current limiting section 43, is input to a subtractor 42B, which calculates a deviation ΔI (=Irefm-Im) from the fed-back motor current value Im, and the deviation ΔI is input to a PI (proportional-integral) control section 45 for improving the characteristics of the steering operation. A voltage control command value Vref, the characteristics of which have been improved by the PI control section 45, is input to a PWM control section 46, and the motor 20 is PWM-driven via an inverter 47 as a drive section. The current value Im of the motor 20 is detected by a motor current detector 48, and is fed back to the subtractor 42B.

[0018] The controller 30 may perform vector control by calculating a q-axis current command value, which is a torque generating component, and a d-axis current command value, which is a magnetic field generating component, as the current command value Iref, and generating a voltage command value based on the deviation between the q-axis motor current detection value and the q-axis current command value and the deviation between the d-axis motor current detection value and the d-axis current command value.

[0019] 3 is a block diagram expressing, by a transfer function, a system in which the motor 20 is driven by the current command value Iref. The current command value Iref is input to a subtractor 51 via a control filter (Gref(s)) 50, and the subtractor 51 calculates the deviation between the output of the control filter 50 and the current value Im of the motor 20 detected by the motor current detector 48. A control filter (A(s)) 52 calculates a first voltage command value according to the deviation between the output of the control filter 50 and the current value Im of the motor 20, and inputs it to an adder 53. The control filter 52 is an example of a "current control unit" recited in the claims.

[0020] The adder 53 adds the output of the adder 53 delayed by the delay element (Gdly) 55 to the first voltage command value and integrates the first voltage command value to calculate the second voltage command value. The adder 53 is an example of a “voltage disturbance suppression unit” recited in the claims. The delay element 55 may be, for example, a delay element that provides a delay corresponding to a control period of current control of the motor current of the motor 20 by the controller 30. For example, the adder 53 calculates the second voltage command value by adding the output value of the adder 53 in the previous cycle of the current control to the first voltage command value in the current cycle.

[0021] The output of the adder 53 is passed through a filter (G LPF The first voltage command value is input to a delay element 55 and a delay element (GDLY) 56 via a filter 54. That is, the filter 54 is a filter that reduces noise in the sum of the first voltage command value and the output of the delay element 55. The filter 54 may be, for example, a low-pass filter. If the detection noise of the current value Im of the motor 20 detected by the motor current detector 48 can be ignored, the filter 54 may be omitted.

[0022] The delay element 56 may be a delay element that provides a delay equivalent to the hardware delay of the controller 30. For example, the delay by the delay element 56 may be a delay from when the motor current detector 48 detects the current value Im of the motor 20 until the PWM control unit 46 outputs PWM using this detected current value Im. The motor's back electromotive force EMF is subtracted from the output from the delay element 56 by a calculation unit 57, and a disturbance voltage ΔV is added to the output from the delay element 56. The calculation unit 57 models the effect of the back electromotive force EMF actually generated in the motor on the output from the delay element 56 (control voltage).

[0023] The calculation result of the calculation unit 57 is converted into a motor current i by being divided by the impedance E(s)=L s+R of the motor 20 in an electrical characteristics unit (1 / E(s)) 58 of the motor 20. Note that the constants L and R are the inductance value and resistance value of the motor 20, respectively. The motor current i is converted to a torque τ by multiplying it by a torque coefficient (Kt) 59. The torque τ is converted to a motor rotation angle θ by a mechanical characteristic section (1 / M(s)) 61. The denominator of the transfer function of the mechanical characteristic section 61 is, for example, M(s)=Js 2 +(D+G CF )s+K, with constants J, D, and G CF , K are the moment of inertia, viscosity coefficient, Coulomb friction coefficient, and spring constant of the motor, respectively.

[0024] The back electromotive force generator (s·Ke) 62 generates a back electromotive force EMF having the same magnitude as the product of the time derivative of the motor rotation angle θ (ie, the motor rotation speed) and the back electromotive force constant Ke. The motor current i is detected by the motor current detector 48 and fed back to the subtractor 51, but due to the current detection error Δi being mixed in the adder 60, the motor current Im is fed back as i+Δi.

[0025] The transfer function with the current command value Iref, the disturbance voltage Δv, the current detection error Δi, the disturbance torque Δτ, and the disturbance angle Δθ of the motor rotation angle as inputs and the motor current i as output is given by the following equation (1).

[0026]

number

[0027] In addition, among the terms on the right side of the above equation (1),

[0028]

number

[0029] In the following description, this part may be referred to as the "input vector." Also, the part that indicates the influence of the physical characteristics of the motor 20 common to each term of the input vector on the right side of the above formula (1)

[0030]

number

[0031] In the following explanation, we may refer to this as the "common term". Also, the part on the right side of the above formula (1) that shows the influence of each term of the input vector

[0032]

number

[0033] In the following explanation, this may be referred to as the "sensitivity vector." Note that in the above formula (1), it is assumed that the effect of the disturbance angle Δθ can be ignored, and the component of the sensitivity vector with respect to the disturbance angle Δθ is set to "0." In this embodiment, the transfer function (GDLY) of the delay element 56 and the transfer function (G LPF The transfer function obtained by removing (s)

[0034]

number

[0035] The transfer function of the component in which the frequency response of has small fluctuation (i.e., has flat frequency characteristics) and the disturbance voltage Δv affects the motor current i is

[0036]

number

[0037] The characteristics of the transfer function of the control filter 52 are set so that it has the characteristics of a high-pass filter (that is, so that it has the characteristics of attenuating low-frequency components). The transfer function of the control filter (A(s)) 52 may be set, for example, as follows:

[0038]

number

[0039] The above formula is an example of a PID (proportional, integral, differential) controller, and the characteristics of the transfer function of the control filter 52 can be appropriately adjusted by changing, for example, parameters Kp, ζ, and ωc. When the transfer function of the control filter 52 is set in this way, the transfer function of the delay element 56 (GDLY) and the transfer function of the filter 54 (G LPF The fluctuation in the frequency response of the transfer function obtained by excluding (s) becomes small, and good response characteristics that are not easily affected by the frequency of the current command value Iref can be realized.

[0040] Furthermore, when vector control is performed, the back electromotive force and the interference term between the d-axis component and the q-axis component can be treated as a low-frequency signal (for example, 10 Hz or less) equivalent to the steering period of the steering wheel 1 on the dq-axis rotating coordinate system. Therefore, the transfer function of the component that affects the motor current i due to the disturbance voltage Δv has the characteristics of a high-pass filter with a cutoff frequency that attenuates low-frequency components, thereby suppressing the effects of the back electromotive force and other disturbance voltages.

[0041] For example, when the numerator of the common term in the transfer function of the above formula (1) is set to 1,

[0042]

number

[0043] When the frequency characteristics shown in FIG. 4(a) and FIG. 4(b) are as shown, the transfer functions (GDLY, G LPF The transfer function obtained by removing (s)

[0044]

number

[0045] In order to reduce the fluctuation in the frequency response, the transfer function A(s) of the control filter 52 is set to have the inverse characteristic to the frequency characteristics exemplified in FIGS. 4(a) and 4(b). 5(a) and 5(b) are Bode plots of an example of the control filter 52 that is set to have the inverse frequency characteristic of the denominator of the common term.

[0046] When the frequency characteristics of the control filter 52 are set as shown in FIG. 5(a) and FIG. 5(b), the transfer functions (GDLY, G LPF The frequency characteristics of the transfer function obtained by excluding (s) are shown in FIG. 6(a) and FIG. 6(b). As shown in FIG. 6(a) and FIG. 6(b), the transfer functions (GDLY, G LPF The fluctuation in the frequency response of the transfer function obtained by excluding (s) is suppressed, realizing a relatively flat frequency characteristic.

[0047] In addition, when the frequency characteristics of the control filter 52 are set as shown in FIG. 5(a) and FIG. 5(b), the transfer function of the component in which the disturbance voltage Δv affects the motor current i is

[0048]

number

[0049] 7(a) and 7(b). The transfer function of the component that the disturbance voltage Δv affects on the motor current i has high-pass filter characteristics, so that the effects on the back electromotive force and other disturbance voltages can be suppressed as described above.

[0050] Next, the effects of the embodiment will be described with reference to Fig. 8(a) and Fig. 8(b) and Fig. 9(a) and Fig. 9(b). Fig. 8(a) and Fig. 8(b) are Bode plots showing the simulation results of the frequency characteristics of the motor current i with respect to the current command value Iref when conventional feedforward type back electromotive force compensation is performed as a comparative example, and Fig. 9(a) and Fig. 9(b) are Bode plots showing the simulation results of the frequency characteristics of the motor current i with respect to the current command value Iref when motor current control is performed by the controller 30 of the embodiment. The solid line indicates the reference frequency characteristics, the dashed line indicates the frequency characteristics at room temperature, the dotted line indicates the frequency characteristics at -40 degrees, and the dashed dotted line indicates the frequency characteristics at 100 degrees.

[0051] Comparing Figures 8(a) and 9(a), it can be seen that when conventional feedforward type back EMF compensation is performed, a decrease in gain occurs in the frequency band of 100 Hz or less due to the influence of a no-pass filter that suppresses the influence of current detection noise, but when motor current control according to the embodiment is performed, the decrease in gain is suppressed in the frequency band of 100 Hz or less. It can also be seen that when the motor current control according to the embodiment is performed, gain changes associated with temperature changes are suppressed in the low frequency band. Also, the higher the temperature, the more the gain fluctuations are suppressed. Electric actuator products and electric power steering devices generate heat by themselves when current is applied, so they are often operated under normal temperature or high temperature conditions rather than under extremely low temperature conditions. The characteristics of the motor current control according to the embodiment are suited to the operating conditions.

[0052] (Variation 1) FIG. 10 is a block diagram showing a second example of a system in which the motor 20 is driven by the current command value Iref, expressed by a transfer function. LPF Instead of the control filter (A(s)) 54, a filter (G LPF (s)) 54a and a filter (G LPF (s)) 54b may be provided separately.

[0053] For example, by placing a filter 54a between the control filter 52 and the adder 53 and placing a filter 54b between the delay element 55 and the adder 53, the first voltage command value in which noise has been reduced by the filter 54a and the output of the delay element 55 in which noise has been reduced by the filter 54b may be added by the adder 53 to calculate the second voltage command value.

[0054] Moreover, a filter 54a may be disposed in front of the control filter 52, and the output of the subtractor 51, in which noise has been reduced by the filter 54a, may be input to the control filter 52. Even in this configuration, noise in the output of the control filter 52 (i.e., the first voltage command value) can be reduced by the filter 54a. Similarly, a filter 54b may be placed in front of the delay element 55, and the output of the adder 53, in which noise has been reduced by the filter 54b, may be input to the delay element 55. Even in this configuration, noise in the output of the delay element 55 can be reduced by the filter 54b.

[0055] (Variation 2) FIG. 11 is a block diagram showing a third example of a system in which the motor 20 is driven by the current command value Iref, expressed by a transfer function. 10, a control filter (A(s)) 52a similar to the control filter 52 may be provided in front of the subtractor 51 (i.e., between the control filter (Gref(s)) 50 and the subtractor 51), and a control filter (A(s)) 52b similar to the control filter 52 may be provided in the feedback path of the current value Im detected by the motor current detector 48 (i.e., between the motor current detector 48 and the subtractor 51). Even with this configuration, the transfer function is equivalent to that of the system shown in FIG.

[0056] Also, the filter (G LPF Instead of the filter (GLPF(s)) 54a, a filter (GLPF(s)) 54a1 that reduces noise in the output of the control filter 52a and a filter (GLPF(s)) 54a2 that reduces noise in the output of the control filter 52b may be provided separately. The filter 54a1 reduces noise in the current command value Iref, and the filter 54a2 reduces noise in the current detection value Im. The connection order of the control filter 50, the control filter 52a, and the filter 54a1 is not limited to that shown in FIG. 11. For example, a filter 54a1 may be provided downstream of the control filter 50 that receives the current command value Iref, and a control filter 52a may be provided downstream of the filter 54a1, with the output of the control filter 52a being input to the subtractor 51.

[0057] In addition, a control filter 50 may be provided downstream of the control filter 52a which receives the current command value Iref, and a filter 54a1 may be provided downstream of the control filter 50, and the output of the filter 54a1 may be input to the subtractor 51. Alternatively, a filter 54a1 may be provided downstream of the control filter 52a which receives the current command value Iref, and a control filter 50 may be provided downstream of the filter 54a1, and the output of the control filter 50 may be input to the subtractor 51.

[0058] In addition, a control filter 50 may be provided downstream of a filter 54a1 that inputs the current command value Iref, and a control filter 52a may be provided downstream of the control filter 50, and the output of the control filter 52a may be input to the subtractor 51. Alternatively, a control filter 52a may be provided downstream of a filter 54a1 that inputs the current command value Iref, and a control filter 50 may be provided downstream of the control filter 52a, and the output of the control filter 50 may be input to the subtractor 51.

[0059] In addition, the order of arrangement of control filter 52b and filter 54a2 in the feedback path of current value Im is not limited to the order in Figure 11. The current value Im detected by motor current detector 48 may be input to filter 54a2, control filter 52b may be provided subsequent to filter 54a2, and the output of control filter 52b may be input to subtractor 51. In addition, both the control filter (A(s)) and the filter (GLPF(s)) are placed upstream of the subtractor 51 and in the feedback path of the current value Im, but only one of the control filter (A(s)) and the filter (GLPF(s)) may be placed upstream of the subtractor 51 and in the feedback path of the current value Im, and the other filter may be placed downstream of the subtractor 51.

[0060] (Effects of the embodiment) (1) The motor control device of the embodiment includes a current command value calculation unit 41 that calculates a current command value Iref for driving the motor 20, a current value detection unit 48 that detects a current flowing through the motor 20, a control filter 52 that outputs a first voltage command value according to the deviation between a current detection value Im, which is a detection value of the current detected by the current value detection unit 48, and the current command value Iref, an adder 53 that adds the output of a delay element 55 to the first voltage command value to calculate a second voltage command value and inputs the second voltage command value to the delay element 55, and an inverter 47 that drives the motor 20 based on the second voltage command value.

[0061] Conventional feedforward types require a model of motor characteristics such as the back electromotive force constant, but this invention does not use this. As a result, even if the back electromotive force constant changes due to variations due to individual differences in the motors used, temperature changes, changes in physical properties due to aging, etc., the disturbance voltage caused by these changes can be suppressed, improving robustness against disturbance factors. In addition, the motor rotation speed used in conventional feedforward type back EMF compensation is calculated from sampled values ​​of the motor angle, which can result in estimation errors due to the influence of detection errors, detection noise, etc.; however, the present invention does not use the motor rotation speed to suppress disturbance voltage, so it is possible to avoid the influence of detection errors and detection noise in the motor rotation speed.

[0062] When calculating the voltage command value by vector control as described above, the current command value calculation unit 41 may calculate a d-axis current command value and a q-axis current command value. Then, the current detection value Im may be converted into a q-axis motor current detection value and a d-axis motor current detection value. The control filter (current control unit) 52 may calculate a first voltage command value according to the deviation between the q-axis motor current detection value and the q-axis current command value and the deviation between the d-axis motor current detection value and the d-axis current command value.

[0063] (2) The control filter 52 may have high-pass filter characteristics with respect to the disturbance voltage applied to the motor 20. As described above, the back electromotive force and the interference term between the d-axis component and the q-axis component can be treated as a low-frequency signal equivalent to the steering period of the steering wheel 1 on the dq-axis rotating coordinate system. Since the control filter 52 has high-pass filter characteristics with respect to disturbance voltages, the effects of the back electromotive force and other disturbance voltages can be suppressed.

[0064] (Modification) The motor control device according to the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit and scope of the present invention. For example, in the above embodiment, an electric power steering device 10 equipped with the motor control device according to the present invention has been described as an example of an application of the motor control device according to the present invention, but the scope of application of the motor control device according to the present invention is not limited to this, and the motor control device can be applied to various mechanical devices that use a motor control device.

[0065] FIG. 12 is a schematic diagram showing an example of a linear motion table device using a motor control device of the present invention. The linear motion table device includes a feed screw device, a table 71, two linear guides (linear motion guide devices), and a base 74. The feed screw device has a screw shaft 70, a nut 76, and a motor 77, and the screw shaft 70 is inserted into the nut 76. The feed screw mechanism of the feed screw device is a ball screw in which the helical groove of the screw shaft 70 and the helical groove of the nut 76 are in point contact via balls (rolling elements). The motor 77 is coupled to one axial end of the screw shaft 70.

[0066] Each of the two linear guides has a guide rail 72, two sliders (moving bodies) 73, and multiple rolling bodies. In the linear guide, the guide rail 72 and the slider 73 each have a raceway surface that forms a rolling passage for the rolling bodies at a position opposite to each other. Both raceway surfaces extend in the longitudinal direction of the guide rail 72, and the slider 73 moves linearly along the guide rail 72 via the rolling bodies that roll under load in the rolling passage. Linear guides are arranged at both ends of a base 74 in a direction perpendicular to the moving direction Y of a table 71, and a feed screw device is disposed between the two linear guides. A guide rail 72 and a screw shaft 70 are arranged parallel to the moving direction Y of the table 71.

[0067] In this arrangement, the guide rail 72 is fixed to a base 74. The screw shaft 70 has rolling bearings attached to both axial ends thereof, and a housing 75 is fixed to the outer ring of the rolling bearing, and each housing 75 is fixed to the base 74. In this way, the screw shaft 70 is supported rotatably relative to the base 74. The table 71 is disposed above the two sliders 73 of each linear guide and the nuts 76 of the feed screw devices, and is fixed directly to the sliders 73 and via a bracket to the nuts 76. In other words, the two sliders 73 of each linear guide and the feed screw devices 76 are fixed to one surface of the table 71.

[0068] In this linear motion table, when the motor 77 is driven to operate the feed screw device, the screw shaft 70 rotates and the nut 76 is linearly moved by the ball screw mechanism. Accordingly, the table 71 is linearly moved while being guided by the linear guide. The controller 78 sets a current command value for driving the motor 77, calculates a voltage control command value Vref from the current command value by the same process as the controller 30 in the above embodiment, and controls the current supplied to the motor 20. [Explanation of symbols]

[0069] 1...steering wheel, 2...steering shaft, 3...reduction gear, 4a, 4b...universal joint, 5...pinion rack mechanism, 5a...pinion, 5b...rack, 6a, 6b...tie rod, 7a, 7b...hub unit, 8L, 8R...steered wheels, 10...torque sensor, 11...key, 12...vehicle speed sensor, 13...battery, 14...steering angle sensor, 20...steering assist motor, 20, 77...motor, 30, 78...controller, 41...current command value calculation unit, 42A, 44-4, 44-5, 53...adder, 42B, 51...subtractor, 43...current limiting unit, 44...compensation signal generating unit, 44-1 ...Convergence, 44-2...Inertia, 44-3...Self-aligning torque, 45...(Proportional integral) control unit, 46...PWM control unit, 47...Inverter, 48...Motor current detector, 50, 52, 52a, 52b...Control filter, 53...Voltage disturbance suppression unit, 54, 54a, 54a1, 54a2, 54b...Filter, 55, 56...Delay element, 57...Calculation unit, 58...Electrical characteristic unit, 59...Torque coefficient, 60...Adder, 61...Mechanical characteristic unit, 62...Back electromotive force generation unit, 70...Screw shaft, 71...Table, 72...Guide rail, 73...Slider, 74...Base, 75...Housing, 76...Nut

Claims

1. a current command value calculation unit that calculates a current command value for driving the motor; a current value detection unit that detects a current flowing through the motor; a current control unit that outputs a first voltage command value in response to a deviation between a current command value and a current detection value that is a detection value of the current detected by the current value detection unit, and has characteristics of proportional control, integral control, and differential control with respect to the deviation; a voltage disturbance suppression unit that calculates a second voltage command value by adding an output of a delay element that is disposed downstream of the current control unit, the delay element providing a delay for a control period of the current control unit to an input signal that was input in a previous control period of the current control unit, and outputs the input signal as a delayed signal in a current control period of the current control unit, to the first voltage command value, and inputs the second voltage command value to the delay element; a drive circuit that drives the motor based on the second voltage command value; A motor control device comprising:

2. 2. The motor control device according to claim 1, further comprising a first filter that reduces noise in the second voltage command value.

3. 3. The motor control device according to claim 2, wherein the first filter is a filter that reduces noise in a sum of the first voltage command value and the output of the delay element.

4. 4. The motor control device according to claim 3, wherein an output of the first filter is input to the delay element.

5. the first filter includes a second filter that reduces noise in the first voltage command value and a third filter that reduces noise in an output of the delay element; 3. The motor control device according to claim 2, wherein the voltage disturbance suppression unit calculates the second voltage command value by adding together the first voltage command value, in which noise has been reduced by the second filter, and an output of the delay element, in which noise has been reduced by the third filter.

6. 2. The motor control device according to claim 1, further comprising a filter for reducing noise in the current command value, a filter for reducing noise in the current detection value, and a filter for reducing noise in the output of the delay element, separately provided.

7. 2. The motor control device according to claim 1, wherein the current control unit has a high-pass filter characteristic with respect to a disturbance voltage applied to the motor.

8. A motor control device according to any one of claims 1 to 7, a motor controlled by the motor control device; An electric actuator product comprising:

9. A motor control device according to any one of claims 1 to 7, a motor controlled by the motor control device; and applying a steering assist force to a steering system of a vehicle by the motor.

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