JP7735938B2 - Motor control device, electric actuator, and electric power steering device - Google Patents

Description

The present invention relates to a motor control device, an electric actuator, and an electric power steering device.

Conventionally, measures against various disturbances (noise) have been required in motor control.
Known examples of disturbances include voltage noise, current detection noise, angle detection noise, torque disturbance, etc. Regarding torque disturbances, measures are required to deal with torque disturbances that the motor itself has and torque disturbances that are transmitted from the outside.
Known torque disturbances inherent in the motor itself include cogging torque, torque ripple due to armature reaction, Coulomb friction, etc. Known torque disturbances transmitted from the outside include reverse input torque from devices and systems connected to the motor shaft, mechanical resonance, and self-aligning torque.
For example, Patent Document 1 proposes a motor control device equipped with a disturbance observer that suppresses only torque disturbances.

JP 2016-163370 A

However, if various suppression functions corresponding to each of the various disturbances are provided, the configuration becomes complicated, and there is a risk that the suppression functions may interfere with each other.
Therefore, an object of the present invention is to accurately suppress various disturbances while avoiding a complicated configuration.

To solve the above problem, one aspect of the motor control device according to the present invention includes a command value calculation unit that calculates a voltage command value based on the difference between a current command value and an actual current value; a rotation speed estimation unit that estimates the rotation speed of the motor based on the actual current value and the rotation angle of the motor; a torque disturbance estimation unit that estimates a torque disturbance based on the actual current value and the estimated rotation speed of the motor; and a torque disturbance suppression unit that calculates a suppression value to be added to the current command value to suppress the estimated torque disturbance.

With this motor control device, the rotation speed estimator can obtain a smooth estimated signal, enabling highly accurate estimation and suppression of torque disturbances. It has also been confirmed that the various disturbances described above can be simultaneously suppressed by feedback control via the rotation speed estimator, torque disturbance estimator, and torque disturbance suppressor.
The motor control device preferably further comprises a high-pass filter that acts on the suppression value before it is added to the current command value. The high-pass filter removes DC components of torque disturbances, thereby realizing a function similar to a notch filter that suppresses disturbances of a specific frequency.

Preferably, the motor control device further comprises a band setting unit that sets a control band by acting on the current command value before the suppression value is added. The band setting unit suppresses noise contained in the current command value and improves current tracking.
In the motor control device, the command value calculation unit preferably has a PID control unit that calculates the voltage command value by PID control based on the difference value, whereby a highly accurate voltage command value can be obtained for causing an actual current to flow through the motor in accordance with the current command value.

Preferably, the command value calculation unit having a PID control unit further includes a low-pass filter that acts on the output of the PID control unit, and a delay element that positively feeds back the voltage command value from the output side of the low-pass filter to the input side with a delay. Since current detection noise contained in the actual current value is cut by the low-pass filter, the accuracy of noise suppression is further improved.
In order to solve the above problem, one aspect of the electric actuator according to the present invention includes any one of the motor control devices described above, and a motor to which a voltage controlled by the motor control device is applied.

With such an electric actuator, various disturbances are suppressed by the control of the motor control device, so that an actual current flows through the motor in accordance with the current command value, thereby obtaining a desired output.
In order to solve the above problem, one aspect of an electric power steering device according to the present invention includes any of the motor control devices described above, a motor to which a voltage controlled by the motor control device is applied, and a power steering mechanism driven by the motor.
According to such an electric power steering device, an actual current flows to the motor in accordance with the current command value, and a desired output is obtained, so that the steering assist accuracy is high.

The present invention makes it possible to accurately suppress various disturbances while avoiding a complex configuration.

1 is a configuration diagram schematically illustrating an embodiment of an electric power steering device. FIG. 2 is a functional block diagram illustrating an example of a functional configuration of a control unit. FIG. 2 is a functional block diagram showing an example of a functional configuration of a voltage command value calculation unit. FIG. 2 is a block diagram showing a specific functional configuration of a rotation speed estimation unit. FIG. 4 is a diagram showing an approximation of a transfer function in the control system shown in FIG. 3 . 10 is a graph showing simulation verification results for a torque disturbance of 1 Hz when the cutoff frequency ω _HPF is 0 Hz. 10 is a graph showing simulation verification results for a 10 Hz torque disturbance when the cutoff frequency ω _HPF is 0 Hz. 10 is a graph showing simulation verification results for a torque disturbance of 100 Hz when the cutoff frequency ω _HPF is 0 Hz. 10 is a graph showing the correspondence relationship between the frequency of torque disturbance and the suppression effect when the cutoff frequency ω _HPF is 0 Hz. 10 is a graph showing simulation verification results for a torque disturbance of 1 Hz when the cutoff frequency ω _HPF is 5 Hz. 10 is a graph showing simulation verification results for a 10 Hz torque disturbance when the cutoff frequency ω _HPF is 5 Hz. 10 is a graph showing simulation verification results for a torque disturbance of 100 Hz when the cutoff frequency ω _HPF is 5 Hz. 10 is a graph showing the correspondence relationship between the frequency of torque disturbance and the suppression effect when the cutoff frequency ω _HPF is 5 Hz. 10 is a graph showing transfer characteristics with respect to voltage noise. 10 is a graph showing transfer characteristics for current detection noise. 10 is a graph showing transfer characteristics for angle detection noise.

Embodiments of the present invention will be described below with reference to the drawings. However, to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art, more detailed descriptions than necessary may be omitted. For example, detailed descriptions of matters that are already well known or duplicate descriptions of substantially identical configurations may be omitted. Furthermore, elements shown in earlier-described figures may be referenced as appropriate in the descriptions of later figures.

In this specification, embodiments of the present disclosure will be described using as an example an electric actuator that supplies power from a power source to a three-phase motor with three-phase (A, B, and C) windings. However, the scope of the present disclosure also includes electric actuators that supply power from a power source to an n-phase motor with n-phase (n is an integer equal to or greater than 4) windings, such as four or five phases.

FIG. 1 is a schematic diagram showing the configuration of an embodiment of an electric power steering device.
The electric power steering device 100 of this embodiment is equipped with a steering mechanism having a steering wheel 1, a column shaft 2, a reduction gear 3, universal joints 4A and 4B, a pinion-rack mechanism 5, and a tie rod 6 for the steered wheels. The electric power steering device 100 also includes a torque sensor 10, a motor 20, a control unit 30, an ignition key 11, a vehicle speed sensor 12, and a battery 14. The combination of the motor 20 and the control unit 30 corresponds to one embodiment of the electric actuator of the present invention, and the control unit 30 corresponds to one embodiment of the motor control device of the present invention. The steering mechanism is driven by the motor 20.

A column shaft 2 of the steering wheel 1 is connected to a tie rod 6 of the steered wheels via a reduction gear 3, universal joints 4A and 4B, and a pinion rack mechanism 5. A torque sensor 10 that detects the steering torque of the steering wheel 1 is provided on the column shaft 2, and a motor 20 that assists the steering force of the steering wheel 1 is connected to the column shaft 2 via the reduction gear 3.
The torque sensor 10 detects the steering torque Th transmitted from the steering wheel 1 due to the driver's steering operation.

A control unit (ECU) 30 that controls the power steering device 100 is supplied with power from a battery 14, which is a power source, and also receives an ignition key signal from an ignition key 11. The control unit 30 calculates a steering assist torque using an assist map or the like based on the steering torque Th detected by the torque sensor 10 and the vehicle speed Vh detected by the vehicle speed sensor 12.
Then, the control unit 30 controls the current I supplied to the motor 20 so as to generate the calculated assist torque. A voltage controlled by the control unit 30 is applied to the motor 20, and the current I is controlled by the controlled voltage. The assist torque generated by driving the motor 20 is applied to the steering system as an assist force for the driver's steering operation (steering assist force), allowing the driver to operate the steering wheel with less force.

The quality of the steering feel is determined by the amount of assist torque generated from the steering torque Th output by steering and the vehicle speed Vh. Furthermore, the performance of the electric power steering device is greatly affected by the accuracy with which the current I required to generate the assist torque is passed to the motor 20.

The control unit 30 may be, for example, a computer including a processor and peripheral components such as a storage device. The processor may be, for example, a CPU (Central Processing Unit) or an MPU (Micro-Processing Unit).
The storage device may include any of semiconductor storage devices, magnetic storage devices, and optical storage devices. The storage device may include memories such as registers, cache memories, and memory used as main storage devices, such as ROMs (Read Only Memory) and RAMs (Random Access Memory).

The control unit 30 may be configured with dedicated hardware, which will be described below, for executing each information processing.
For example, the control unit 30 may include a functional logic circuit configured in a general-purpose semiconductor integrated circuit, or may include a programmable logic device (PLD) such as a field-programmable gate array (FPGA).

FIG. 2 is a functional block diagram showing an example of the functional configuration of the control unit 30.
The control unit 30 includes a current command value calculation unit 40, a voltage command value calculation unit 45, a two-phase/three-phase conversion unit 46, a PWM (Pulse Width Modulation) control unit 47, an inverter 48, and a three-phase/two-phase conversion unit 49, and drives the motor 20 by vector control. The motor 20 is, for example, a three-phase motor.
The functions of the current command value calculation unit 40, the voltage command value calculation unit 45, the two-phase/three-phase conversion unit 46, the PWM control unit 47, and the three-phase/two-phase conversion unit 49 are realized, for example, by the processor of the control unit 30 executing a computer program stored in a storage device.

The current command value calculation unit 40 calculates current command values Iq0 and Id0 that indicate the currents of the d and q axes that should be passed to the motor 20 based on the steering torque Th and the vehicle speed Vh.
On the other hand, the currents ia, ib, ic flowing in each phase of the motor 20 are detected by current sensors 60, 61, 62 provided in each layer, and the detected currents ia, ib, ic are converted into actual current values id, iq of the dq2 axes by the three-phase/two-phase conversion unit 49 and fed back.

The current command values Iq0, Id0 are input to the voltage command value calculation unit 45, and the fed-back actual current values id, iq are also input. The voltage command value calculation unit 45 calculates voltage command values vq, vd such that the difference between the current command values Iq0, Id0 and the actual current values id, iq is zero. The two-phase/three-phase conversion unit 46 converts the voltage command values vd, vq into three-phase voltage command values va, vb, vc.

The PWM control unit 47 generates PWM-controlled gate signals based on the three-phase voltage command values va, vb, and vc. The inverter 48 is driven by the gate signals generated by the PWM control unit 47 and applies voltages indicated by the three-phase voltage command values va, vb, and vc to each phase of the motor 20. As a result, currents indicated by the current command values Iq0 and Id0 are supplied to the motor 20.

The resolver 63 detects the motor angle (rotation angle) θ of the motor 20, and the detected motor angle θ is fed back to the current command value calculation unit 40 and used for vector control. A motor rotation angle sensor may be used instead of the resolver 63. Note that the rotation angular velocity ω of the motor 20 calculated based on changes in the motor angle θ may be input to the current command value calculation unit 40 together with the motor angle θ or instead of the motor angle θ.

Fig. 3 is a functional block diagram showing an example of the functional configuration of the voltage command value calculation unit 45. Fig. 3 also shows a model of the motor 20. Fig. 3 shows the control function of the q axis as a representative, but the voltage command value calculation unit 45 also has a similar control function for the d axis.
The function of the motor 20 is represented by a model having electrical characteristics 21, a torque constant _KT , mechanical characteristics 23, an integral element 24, and an EMF (back electromotive force) coefficient _KE .

An actual current is generated when a voltage is input to the electrical characteristic 21 of the motor 20. The voltage value input to the electrical characteristic 21 includes voltage noise. The gain of the electrical characteristic 21 is expressed as 1/(Ls+R) where L is an inductance [H] and R is a resistance [Ω]. The actual current is detected by current sensors 60, 61, and 62, and the detected value includes current detection noise.
A torque constant K _T [Nm/A] acts on the actual current to generate a motor torque.

The angular velocity of the motor 20 is generated by inputting the motor torque to the mechanical characteristic 23. The gain of the mechanical characteristic 23 is expressed as 1/(Js+D) where J is the inertia [kgm ² ] and D is the viscosity [Nm/(rad/s)].
The angular velocity of the motor 20 passes through an integral element 24 to become a motor angle θ. The motor angle θ is detected by a resolver 63 (or a motor rotation angle sensor), and the detected value contains angle detection noise.

The EMF coefficient K _E [V/(rad/s)] acts on the angular velocity to generate a back electromotive force, which is reflected in the input of the electrical characteristic 21 .
The voltage command value calculation unit 45 includes a control band setting unit 70, a PID (Proportional Integral Differential) control unit 71, a low-pass filter 72, a first delay element 73, a second delay element 75, and a disturbance suppression unit 76.

The control band setting unit 70 receives the current command value Iq0 and applies a gain _Gref to the current command value, thereby setting a control band for current control of the motor 20 by the control unit 30. The control band setting unit 70 applies a gain Gref to the current command value Iq0 before a suppression value, which will be described later, is added. The gain _Gref of the control band setting unit 70 is expressed as follows:
G _ref =ω _ref /(s+ω _ref )
however,
s: Laplace operator ω _ref [rad/s]: current control band.

The PID control unit 71 receives a difference value Δq between the current command value Iq0 and the q-axis actual current value iq, and calculates a voltage command value vq by PID control based on the difference value Δq. The gain G _PID in the PID control unit 71 is expressed as follows:
G _PID = {ω _c L+(R/2)}[1+{ω _c /(2s)}+{s/(2ω _c )}]
however,
s: Laplace operator ω _c [rad/s]: disturbance suppression band L [H]: inductance of the motor R [Ω]: resistance of the motor.

The low-pass filter 72 acts on the voltage command value vq, which is the output of the PID control unit 71, to cut current detection noise contained in the q-axis actual current value iq. The gain G _LPF of the low-pass filter 72 is expressed as follows:
G _LPF = ω _LPF / (s+ω _LPF )
however,
s: Laplace operator ω _LPF [rad/s]: Cutoff frequency.

The first delay element 73 functions as a back electromotive force suppressor by feedback with a delay. The gain G _dly in the first delay element 73 is expressed as follows:
G _dly = e ^-Tdly・s
however,
Tdly [μs]: Expressed as the current control period.

The second delay element 75 represents a delay in the feedback loop. The gain G _DLY of the second delay element 75 is expressed as follows:
G _DLY = e ^-TDLY・s
however,
TDLY [μs]: represents the calculation time from current detection by the current sensors 60, 61, 62 to reflection of the duty in the output of the inverter 48.

The disturbance suppression unit 76 calculates a suppression value to be added to the current command value Iq0 to suppress control disturbances, based on the q-axis actual current value iq and the motor angle θ. The disturbance suppression unit 76 includes a rotation speed estimator 80, a torque disturbance estimator 81, a torque disturbance suppression unit 82, and a high-pass filter 83.
The rotation speed estimator 80 estimates the rotation speed of the motor 20 from the q-axis actual current value iq and the motor angle θ. The rotation speed estimator 80 provides a smooth estimated rotation speed value.

FIG. 4 is a block diagram showing a specific functional configuration of the rotation speed estimation unit 80.
The functional blocks shown in FIG. 4 correspond to the following formulas (1) and (2).
however,
z = Ce ^λs
λ: characteristic root j [kgm ² ]: inertia of motor under control d [Nm/(rad/s)]: viscosity of motor under control k _T [Nm/A]: torque constant of motor under control k: stiffness of motor under control i: actual q-axis current value x ₁ : motor angle.
That is, the q-axis actual current value i and the motor angle _x1 are input to the rotation speed estimator 80, and the rotation speed estimator 80 outputs an estimated rotation speed value _x2 (added with ^). The first block 51, the second block 52, and the third block 53 of the rotation speed estimator 80 correspond to the first term, the second term, and the third term of equation (1), respectively. The fourth block 54 of the rotation speed estimator 80 corresponds to the second term of equation (2). The rotation speed estimated value _x2 (added with ^) is input to the first block 51, the motor angle _x1 is input to the second block 52 and the fourth block 54, and the q-axis actual current value i is input to the third block 53. The outputs of the first block 51, the second block 52, and the third block 53 are added together and input to the integral element 55. The outputs of the integral element 55 and the fourth block 54 are added together to obtain the estimated rotation speed value _x2 (added with ^).

Returning to FIG. 3, the description will continue.
The transfer function Gω in the rotation speed estimation unit 80 is expressed by the matrix T in the following equation (3).
however,
ω _est [rad/s]: Estimated rotation speed value ω _obs [rad/s]: Cutoff angular frequency in rotation speed estimation

The torque disturbance estimator 81 estimates the torque disturbance based on the q-axis actual current value iq and the estimated rotation speed value. The transfer function G _TRQ in the torque disturbance estimator 81 is expressed by the matrix T in the following equation (4).
where Δτ _est is an estimated torque disturbance value.

The torque disturbance suppression unit 82 calculates a suppression value to be added to the current command value iq in order to suppress the estimated torque disturbance. The gain G _cmp in the torque disturbance suppression unit 82 is expressed by the following equation (5).
where ω _c is the disturbance suppression band.

The high-pass filter 83 acts on the suppression value before it is added to the current command value Iq0 to remove the DC component of the torque disturbance. The high-pass filter 83 functions like a notch filter, suppressing disturbances of a specific frequency. The gain G _HPF of the high-pass filter 83 is expressed as G _HPF = s/(s + ω _HPF ) using the cutoff frequency ω _HPF .
The disturbance suppression unit 76 can accurately suppress torque disturbances by estimating the torque disturbances, and can also suppress voltage noise, current detection noise, and angle detection noise.

FIG. 5 is a diagram showing an approximation of the transfer function in the control system shown in FIG.
The transfer function in the control system is roughly divided into a characteristic compensation portion of the disturbance suppression unit 76, a loop transfer function portion of the current control system, and a sensitivity function portion. The characteristic compensation portion of the disturbance suppression unit 76 represents characteristic compensation of the mechanical system in the disturbance suppression unit 76, and includes a portion corresponding to the mechanical system on the actual machine side and a portion corresponding to the mechanical system on the control side. The mechanical system on the actual machine side refers to the actual mechanical characteristics of the motor 20, and the mechanical system on the control side refers to the mechanical characteristics set on the control side for control.

The open-loop transfer function portion of the current control system includes the actual portion of the motor 20 and the main control portion from the PID control unit 71 to the second delay element 75 .
The sensitivity function portion is approximately zero for the voltage noise Δv, has first-order high-pass filter characteristics for the current detection noise Δi and the torque disturbance Δτ, and has second-order high-pass filter characteristics for the angle detection noise Δθ. Therefore, it can be seen that the control system shown in Figure 3 can suppress all of the various types of noise by the disturbance suppression unit 76.

6 to 8 are graphs showing simulation verification results of the disturbance suppression unit 76 when the cutoff frequency ω _HPF is 0 Hz.
FIG. 6 shows the simulation verification results for a torque disturbance of 1 Hz, FIG. 7 shows the simulation verification results for a torque disturbance of 10 Hz, and FIG. 8 shows the simulation verification results for a torque disturbance of 100 Hz.
The horizontal axis of each of the graphs shown in FIGS. 6 to 8 indicates time.

In the simulation verification shown in Figure 6, a q-axis current command value fixed at 0 [A] was used, as shown by the thin solid line in Figure 6(A), and a 1 Hz torque disturbance [Nm], as shown by the thin solid line in Figure 6(D), was applied as a torque disturbance. The amplitude of the torque disturbance was ±0.21 [Nm]. This torque disturbance generates an actual current [A], as shown by the thick solid line in Figure 6(A), and also generates a rotation speed [rpm], as shown by the thick solid line in Figure 6(B).

The rotation speed estimator 80 of the disturbance suppression unit 76 calculates an estimated rotation value [rpm] as shown by the thin solid line in FIG. 6B, and the estimated value obtained is close to the rotation speed shown by the thick solid line. The torque disturbance estimator 81 calculates an estimated torque disturbance value [Nm] as shown by the thin solid line in FIG. 6D, and the estimated value obtained is close to the torque disturbance shown by the thin solid line in FIG. 6D. The torque disturbance suppression unit 82 calculates a torque disturbance suppression value [A] as shown by the thick solid line in FIG. 6C. Because the cutoff frequency ω _HPF is 0 Hz, the calculated suppression value [A] is output directly from the disturbance suppression unit 76 as shown by the thick solid line in FIG. 6D. As a result, the motor torque after suppression was ±0.01 [Nm], confirming a significant suppression effect of -27 [dB].

In the simulation verification shown in Figure 7, a q-axis current command value fixed at 0 [A] was used, as shown by the thin solid line in Figure 7(A). Furthermore, a 10 Hz torque disturbance [Nm] was applied as shown by the thin solid line in Figure 7(B). The torque disturbance had an amplitude of ±0.21 [Nm]. This torque disturbance generated an actual current [A] as shown by the thick solid line in Figure 7(A). In the simulation verification shown in Figure 7, the motor torque after suppression was ±0.075 [Nm] as shown by the thick solid line in Figure 7(B), confirming a suppression effect of -8 [dB].

In the simulation verification shown in Figure 8, a q-axis current command value fixed at 0 [A] was used, as shown by the thin solid line in Figure 8(A). Furthermore, a 100 Hz torque disturbance [Nm] was applied as shown by the thin solid line in Figure 8(B). The torque disturbance had an amplitude of ±0.21 [Nm]. This torque disturbance generated an actual current [A] as shown by the thick solid line in Figure 8(A). In the simulation verification shown in Figure 8, the motor torque after suppression was ±0.25 [Nm] as shown by the thick solid line in Figure 8(B), an increase of 1.5 [dB].

FIG. 9 is a graph showing the correspondence relationship between the frequency of torque disturbance and the suppression effect when the cutoff frequency ω _HPF is 0 Hz.
The horizontal axis of Fig. 9 is a logarithmic axis showing the frequency of the torque disturbance, and the vertical axis of Fig. 9 shows the amplitude of the motor torque after suppression in the upper graph and the phase in the lower graph. The circled areas shown in the graphs correspond to the simulation verification results shown in Figs. 6 to 8.
From the amplitude graph shown in the upper part of FIG. 9 , it was confirmed that when the graph cutoff frequency ω _HPF is 0 Hz, the amplitude of the motor torque after suppression falls below 0 [dB] in a band of approximately 40 Hz or less, and therefore torque disturbance is suppressed in a band of approximately 40 Hz or less.

10 to 12 are graphs showing simulation verification results of the disturbance suppression unit 76 when the cutoff frequency ω _HPF is 5 Hz.
FIG. 10 shows the simulation verification results for a torque disturbance of 1 Hz, FIG. 11 shows the simulation verification results for a torque disturbance of 10 Hz, and FIG. 12 shows the simulation verification results for a torque disturbance of 100 Hz.
The horizontal axis of each of the graphs shown in FIGS. 10 to 12 indicates time.

In the simulation verification shown in Figure 10, a q-axis current command value fixed at 0 [A] was used, as shown by the thin solid line in Figure 10(A), and a 1 Hz torque disturbance [Nm], as shown by the thin solid line in Figure 10(B), was applied as a torque disturbance. The amplitude of the torque disturbance was ±0.21 [Nm]. This torque disturbance generates an actual current [A], as shown by the thick solid line in Figure 10(A). As shown by the thick solid line in Figure 10(B), the motor torque after suppression was ±0.21 [Nm], with no increase or decrease at 0 [dB].

In the simulation verification shown in Figure 11, a q-axis current command value fixed at 0 [A] was used, as shown by the thin solid line in Figure 11(A). Furthermore, a 10 Hz torque disturbance [Nm], as shown by the thin solid line in Figure 11(B), was applied as a torque disturbance. The torque disturbance had an amplitude of ±0.21 [Nm]. This torque disturbance generated an actual current [A], as shown by the thick solid line in Figure 11(A). In the simulation verification shown in Figure 11, the motor torque after suppression was ±0.03 [Nm], as shown by the thick solid line in Figure 11(B), confirming a suppression effect of -17 [dB].

In the simulation verification shown in Figure 12, a q-axis current command value fixed at 0 [A] was used, as shown by the thin solid line in Figure 12(A). Furthermore, a 100 Hz torque disturbance [Nm], as shown by the thin solid line in Figure 12(B), was applied as a torque disturbance. The torque disturbance had an amplitude of ±0.21 [Nm]. This torque disturbance generated an actual current [A], as shown by the thick solid line in Figure 12(A). In the simulation verification shown in Figure 12, the motor torque after suppression was ±0.25 [Nm], an increase of 1.5 [dB], as shown by the thick solid line in Figure 12(B).

FIG. 13 is a graph showing the correspondence relationship between the frequency of torque disturbance and the suppression effect when the cutoff frequency ω _HPF is 5 Hz.
The horizontal axis of Fig. 13 is a logarithmic axis showing the frequency of the torque disturbance, and the vertical axis of Fig. 13 shows the amplitude of the motor torque after suppression in the upper graph and the phase in the lower graph. The circled areas shown in the graphs correspond to the simulation verification results shown in Figs. 10 to 12.
13, when the graph cutoff frequency ω _HPF is 5 Hz, the amplitude of the motor torque after suppression falls below 0 [dB] in a band of approximately 50 Hz or less, and the amplitude reaches a minimum value particularly in the vicinity of 10 Hz. In other words, it was confirmed that torque disturbance is suppressed in a specific band around 10 Hz.

FIG. 14 is a graph showing the transfer characteristics with respect to voltage noise.
The horizontal axis in Fig. 14 is a logarithmic axis representing the frequency of the voltage noise, and the vertical axis in Fig. 14 represents the amplitude of the voltage noise in the upper graph and the phase in the lower graph.
In the graph of Figure 14, the transfer characteristics without the disturbance suppression unit 76 are shown by a solid line, and the transfer characteristics with the disturbance suppression unit 76 are shown by a dotted line. It was confirmed that the transfer function for voltage noise has reduced sensitivity over the entire frequency range of voltage noise. Therefore, voltage noise is suppressed by the disturbance suppression unit 76 over the entire frequency range.

FIG. 15 is a graph showing the transfer characteristics for current detection noise.
The horizontal axis in Fig. 15 is a logarithmic axis representing the frequency of the current detection noise, and the vertical axis in Fig. 15 represents the amplitude of the current detection noise in the upper graph and the phase in the lower graph.
15, the transfer characteristics when the disturbance suppression unit 76 is not provided are shown by thin solid lines. Furthermore, the transfer characteristics when the disturbance suppression band _ωc is 1 [Hz] are shown by thick solid lines, and the transfer characteristics when the disturbance suppression band _ωc is 10 [Hz] are shown by thin dotted lines. Furthermore, the transfer characteristics when the disturbance suppression band _ωc is 100 [Hz] are shown by thick dotted lines, and the transfer characteristics when the disturbance suppression band _ωc is 1000 [Hz] are shown by dashed-dotted lines.
15, it was confirmed that the transfer characteristics for the current detection noise are such that the gain is reduced like a high-pass filter characteristic in the region below the disturbance suppression band _ωc . Therefore, the current detection noise is reduced by the disturbance suppression unit 76 like a high-pass filter.

FIG. 16 is a graph showing the transfer characteristics for angle detection noise.
The horizontal axis in Fig. 16 is a logarithmic axis representing the frequency of the angle detection noise, and the vertical axis in Fig. 16 represents the amplitude of the angle detection noise in the upper graph and the phase in the lower graph.
16, the transfer characteristics when the disturbance suppression unit 76 is not provided are shown by thin solid lines. Furthermore, the transfer characteristics when the disturbance suppression band _ωc is 1 [Hz] are shown by thick solid lines, and the transfer characteristics when the disturbance suppression band _ωc is 10 [Hz] are shown by thin dotted lines. Furthermore, the transfer characteristics when the disturbance suppression band _ωc is 100 [Hz] are shown by thick dotted lines, and the transfer characteristics when the disturbance suppression band _ωc is 1000 [Hz] are shown by dashed-dotted lines.
16, it was confirmed that the transfer characteristics for the angle detection noise also reduce the gain like a high-pass filter characteristic in the region below the disturbance suppression band _ωc . Therefore, the angle detection noise is also reduced by the disturbance suppression unit 76 like a high-pass filter.

By precisely suppressing various types of noise, an electric actuator equipped with a motor 20 and a control unit 30 can obtain the desired output by allowing an actual current to flow through the motor 20 in accordance with the current command value. Furthermore, in the electric power steering device 100 shown in Figure 1, the motor 20 can obtain the desired output, resulting in high steering assist accuracy.

Note that while the above description shows an example of application to a power steering device, the electric actuator and motor control device of the present invention can be applied to a wide range of fields, including vehicle drive systems and robots. In other words, the embodiments and scope of application of the present invention are not limited to power steering devices.

100... electric power steering device, 1... steering handle, 2... column shaft,
3...reduction gear, 4A, 4B...universal joint, 5...pinion rack mechanism,
6...steered wheel tie rod, 10...torque sensor, 11...ignition key,
12... vehicle speed sensor, 14... battery, 20... motor, 30... control unit,
40...current command value calculation unit, 45...voltage command value calculation unit, 46...two-phase/three-phase conversion unit,
47... PWM control unit, 48... inverter, 49... three-phase/two-phase conversion unit,
60, 61, 62...current sensors, 63...resolver, 70...control band setting unit,
71... PID control unit, 72... low-pass filter, 73... first delay element,
75... second delay element, 76... disturbance suppression unit, 80... rotation speed estimation unit,
81...torque disturbance estimation unit, 82...torque disturbance suppression unit, 83...high-pass filter

Claims (7)

a command value calculation unit that calculates a voltage command value based on a difference between a current command value and an actual current value;
a rotation speed estimation unit that estimates the rotation speed of the motor based on the actual current value and the rotation angle of the motor;
a torque disturbance estimation unit that estimates a torque disturbance based on the actual current value and the estimated rotation speed of the motor;
a torque disturbance suppression unit that calculates a suppression value to be added to the current command value in order to suppress the estimated torque disturbance;
A motor control device comprising: The motor control device of claim 1, further comprising a high-pass filter that acts on the suppression value before it is added to the current command value. The motor control device of claim 1 further comprising a band setting unit that sets a control band by acting on the current command value before the suppression value is added. The motor control device described in claim 1, wherein the command value calculation unit includes a PID control unit that calculates the voltage command value using PID control based on the difference value. The motor control device described in claim 4, wherein the command value calculation unit further includes a low-pass filter that acts on the output of the PID control unit, and a delay element that positively feeds back the voltage command value from the output side to the input side of the low-pass filter with a delay. The motor control device according to any one of claims 1 to 5,
a motor to which a voltage controlled by the motor control device is applied;
An electric actuator equipped with The motor control device according to any one of claims 1 to 5,
a motor to which a voltage controlled by the motor control device is applied;
a power steering mechanism driven by the motor;
An electric power steering device equipped with