JP2011121383A - Electric power steering control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a vibration extracting filter and a control gain variable to optimize the disturbance vibration inhibiting effect, and to sufficiently lower a disturbance vibration component such as torque ripple and cogging torque generated by a motor. <P>SOLUTION: An electric power steering control device includes an assist map 20 calculating a target current It based on a detected steering torque signal Tsp showing steering torque, a current control means 3 controlling the current flowing in the motor 5 based on the target current It, the vibration extracting filter 8 outputting a vibration component signal by filter-processing a steering torque signal Tsr, a BPF gain 9 calculating a disturbance compensation command Trc based on the vibration component signal, and a BPF frequency map 15 correcting the filter frequency of the vibration extracting filter 8 based on the rotational speed of the motor 5, and the assist map 20 performs processing with a signal added with the disturbance compensation command Trc onto the steering torque signal Tsr being a new steering torque signal. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electric power steering control device that assists a steering torque of a driver of an automobile, and more particularly to a device that suppresses vibration due to disturbance or the like.

  In the conventional electric power steering device, assist torque is determined approximately proportional to the steering torque, and a large torque proportional gain, which is the proportional relationship, is set large, thereby reducing the steering torque of the vehicle driver and providing an appropriate steering fee. Giving a ring is done.

  In addition, the electric power steering device suppresses torque ripples and cogging torque generated by the motor, pulsations generated in synchronization with gear teeth, and vibrations (disturbance vibrations) such as shimmy vibrations. There is a demand for improving the ring (vibration feeling).

  A conventional electric power steering control device is, for example, as described in Patent Document 1. This includes a band pass filter (BPF) and a phase compensator, extracts vibration components due to disturbances with the BPF, further improves the phase characteristics by the phase compensator, and adds the gain multiplied to the target current. By feeding back, the effect of suppressing disturbance is enhanced. At this time, the center frequency, the phase compensation amount, and the gain of the BPF can be made variable according to the vehicle speed so that the characteristics can be matched to the vehicle characteristics.

  Another conventional electric power steering apparatus is disclosed in, for example, Patent Document 2. This also extracts the vibration component by the BPF and suppresses the disturbance by feeding back the vibration component. The frequency of the BPF is made variable according to the vehicle speed.

JP 2009-512278 A Japanese Patent No. 4229929

  In the conventional electric power steering apparatus as described in Patent Document 2, when the frequency of the BPF is made variable, the disturbance vibration frequency estimated by the vehicle speed is included in the BPF passband, and the phase shift is caused. It is only set so that disturbance vibrations are extracted without being generated, and is not configured to optimize the frequency of the BPF in order to suppress the disturbance vibrations. Therefore, there is a problem that the disturbance vibration suppressing effect cannot be expected.

  Further, in the conventional electric power steering apparatus as described in Patent Document 1, when the BPF and the gain are made variable according to the steering angular speed, the motor rotation speed, etc., how to calculate the frequency of disturbance vibration, There is no intention about how the disturbance vibration suppression effect can be improved by making the BPF or gain variable with respect to the frequency, and nothing is described about it. Therefore, even in Patent Document 1, there is a problem that the disturbance vibration suppressing effect cannot be expected. Further, in Patent Document 1, since the frequency of the BPF is only set so as to simply extract the disturbance vibration, it is necessary to newly add a phase compensator in order to improve the phase characteristics. There was also a point.

  The present invention has been made to solve such a problem. The vibration extraction filter and the control gain are made variable so as to optimize the disturbance vibration suppression effect, and the torque ripple generated by the motor, the cogging torque, etc. An object of the present invention is to obtain an electric power steering control device capable of sufficiently reducing the disturbance vibration component of the motor.

  The present invention provides an assist map for calculating a target current based on a detected steering torque signal indicating a steering torque applied to a steering wheel, a current control means for controlling a current flowing through a motor based on the target current, and the steering A vibration extraction filter that outputs a vibration component signal by filtering a torque signal or a rotation angle or rotation speed of the motor, a vibration suppression control gain that calculates a disturbance compensation command based on the vibration component signal, and the motor or Filter frequency correction means for correcting the filter frequency of the vibration extraction filter based on the rotation speed of the steering wheel, and newly adding a signal obtained by adding or subtracting the disturbance compensation command to the steering torque signal or the target current As the steering torque signal or target current, An electric power steering control apparatus characterized by performing the processing by the strike map or the current control unit.

  The present invention provides an assist map for calculating a target current based on a detected steering torque signal indicating a steering torque applied to a steering wheel, a current control means for controlling a current flowing through a motor based on the target current, and the steering A vibration extraction filter that outputs a vibration component signal by filtering a torque signal or a rotation angle or rotation speed of the motor, a vibration suppression control gain that calculates a disturbance compensation command based on the vibration component signal, and the motor or Filter frequency correction means for correcting the filter frequency of the vibration extraction filter based on the rotation speed of the steering wheel, and newly adding a signal obtained by adding or subtracting the disturbance compensation command to the steering torque signal or the target current As the steering torque signal or target current, Since the electric power steering control device is characterized in that the process is performed by a stmap or the current control means, the vibration extraction filter and the control gain are varied to optimize the disturbance vibration suppression effect, and the motor is generated. It is possible to sufficiently reduce disturbance vibration components such as torque ripple and cogging torque.

It is a block diagram which shows the structure of the electric power steering control apparatus which concerns on Embodiment 1 of this invention. It is explanatory drawing which showed the frequency characteristic of the vibration extraction filter in the electric power steering control apparatus which concerns on Embodiment 1 of this invention with the graph. It is the input-output characteristic figure which showed the BPF frequency map in the electric power steering control apparatus which concerns on Embodiment 1 of this invention. FIG. 3 is an input / output characteristic diagram showing a BPF gain map in the electric power steering control device according to the first embodiment of the present invention. It is an example of the disturbance transmission characteristic in the electric power steering control device according to the first embodiment of the present invention (when the disturbance vibration is 60 Hz), and is an explanatory diagram showing the effect of suppressing the disturbance vibration according to the present invention. It is an example of the disturbance transmission characteristic in the electric power steering control device according to the first embodiment of the present invention (when the disturbance vibration is 30 Hz), and is an explanatory diagram showing the effect of suppressing the disturbance vibration according to the present invention. It is explanatory drawing showing the open-loop circuit transfer function (when disturbance vibration is 30 Hz) in the electric power steering control device according to Embodiment 1 of the present invention. It is an example of the disturbance transmission characteristic in the electric power steering control device according to the first embodiment of the present invention, and is an explanatory diagram showing the effect of suppressing disturbance vibration according to the present invention. It is a block diagram which shows the structure of the electric power steering control apparatus which concerns on Embodiment 2 of this invention. It is the input-output characteristic figure which showed the BPF frequency map in the electric power steering control apparatus which concerns on Embodiment 2 of this invention. It is the input-output characteristic figure which showed the BPF gain map in the electric power steering control apparatus which concerns on Embodiment 2 of this invention. It is the input-output characteristic figure which showed the HPF frequency map in the electric power steering control apparatus which concerns on Embodiment 2 of this invention. It is the input-output characteristic figure which showed the HPF gain map in the electric power steering control apparatus which concerns on Embodiment 2 of this invention. (A) It is an example of the disturbance transmission characteristic in Embodiment 2 of this invention, is explanatory drawing showing the suppression effect of the disturbance vibration by this invention (when disturbance vibration is 30 Hz), (b) Implementation of this invention It is explanatory drawing showing the open-loop circuit transfer function in the form 2 of (when disturbance vibration is 30 Hz). It is an example of the disturbance transmission characteristic in Embodiment 2 of this invention, and is explanatory drawing showing the suppression effect of the disturbance vibration by this invention. It is a block diagram which shows the structure of the electric power steering control apparatus which concerns on Embodiment 3 of this invention. It is a block diagram which shows the structure of the electric power steering control apparatus which concerns on Embodiment 4 of this invention. It is a flowchart which shows operation | movement of the switchback detection part in the electric power steering control apparatus which concerns on Embodiment 4 of this invention. It is the wave form diagram which showed an example of the weighting factor in the electric power steering control apparatus which concerns on Embodiment 4 of this invention.

Embodiment 1 FIG.
1 is a block diagram showing a configuration of an electric power steering control apparatus according to Embodiment 1 of the present invention. A detailed description of the electric power steering device itself is omitted here, but it may be of a well-known configuration. For example, those described in Patent Documents 1 and 2 can be referred to.

  In FIG. 1, 1 is a torque sensor, 2 is a phase compensator, 3 is current control means, 4 is a drive circuit, 5 is a motor, 6 is current detection means, 7 is rotational speed detection means, 8 is a vibration extraction filter, 9 Is a vibration suppression control gain (BPF gain), 10 is an adder, 14 is a low pass filter (LPF), 15 is a BPF frequency map, 16 is a BPF gain map, 19 is a saturation means, and 20 is an assist map.

The operation will be described.
A steering torque τ0 applied to the steering wheel by the driver when the driver steers is detected by a torque sensor 1 using a known torsion bar or the like, and based on an output from the torque sensor 1, a phase compensator is detected. 2 advances the phase in the vicinity of the oscillation frequency so as to obtain a stability margin against oscillation vibration that tends to occur when the feedback gain is increased by the assist map 20, and obtains the steering torque signal Tsp. Next, a disturbance compensation command Trc, which will be described later, is added to the steering torque signal Tsp by the adder 10 to correct the steering torque signal. Based on the corrected steering torque signal, the motor 5 The target current It given to is calculated. Note that the vehicle speed Vx, which is a signal for detecting the vehicle speed, is also input to the assist map 20, and the input / output characteristics of the assist map 20 are changed by the vehicle speed Vx. In this way, the target current It output from the assist map 20 is given to the motor 5 via the current control means 3 and the drive circuit 4, and the rotation speed of the motor 5 is detected by the rotation speed detection means 7. In addition, the structure of the rotational speed detection means 7 is not specifically limited, A well-known thing may be used. The current control means 3 and the drive circuit 4 will be described later. In the above description, the steering torque signal is corrected by the disturbance compensation command Trc. However, the present invention is not limited to this, and the target current It may be corrected.

  Next, a part related to generation of the disturbance compensation command Trc will be described. By filtering the steering torque signal Tsp from the phase compensator 2 by the vibration extraction filter 8 having the input / output characteristics shown in FIG. 2, components other than disturbance vibration such as steering components and noise components are reduced from the steering torque signal Tsp. Then, the disturbance vibration component is generally extracted and the vibration component signal Sb is output. As will be described later, depending on the setting of the filter frequency, the phase of the disturbance vibration component can be simultaneously corrected. Further, the object to be filtered in the vibration extraction filter 8 may be the rotation angle or the rotation speed of the motor 5 instead of the steering torque signal Tsp. The configuration of the vibration extraction filter 8 will be described later. Next, the BPF compensation command Tb is calculated by multiplying the vibration component signal Sb by a BPF gain (Kbpf) 9 that is a vibration suppression control gain. A saturation process is performed on the BPF compensation command Tb by the saturation means 19 to generate a disturbance compensation command Trc. The center frequency of the BPF that is the vibration extraction filter 8 and the BPF gain 9 are configured to be variable according to the rotational speed of the motor as follows.

  The rotational speed detection signal ωm detected by the rotational speed detection means 7 is filtered by a low-pass filter (LPF) 14 that removes vibration components to obtain a rotational speed signal Sn. Based on the rotational speed signal Sn, the disturbance frequency conversion means 23 calculates the disturbance frequency signal fd. Next, the disturbance frequency signal fd is input to the BPF frequency map 15 and the BPF gain map 16, and the BPF center frequency fbpf and the BPF gain Kbpf are calculated according to the characteristics shown in FIGS. The calculated value fbpf obtained from the BPF frequency map 15 is set as the center frequency fbpf of the vibration extraction filter 8. Further, the calculated value BPF gain Kbpf obtained from the BPF gain map 16 is multiplied by the vibration component signal Sb as the BPF gain 9 to calculate the BPF compensation command Tb.

  The BPF frequency map 15 can be said to be filter frequency correction means for correcting the center frequency (filter frequency) of the vibration extraction filter 8 based on the disturbance frequency. The BPF gain map 16 can be said to be control gain correction means for correcting the BPF gain 9 that is a vibration suppression control gain based on the disturbance frequency.

  As described above, in the present embodiment, the disturbance frequency is calculated from the rotation speed and is simply set as the filter frequency, or the vibration extraction filter is configured to pass the disturbance frequency without phase shift. Rather, the filter frequency can be set by correcting the calculated disturbance frequency. Moreover, the disturbance vibration suppression effect can be optimized by using the degree of freedom by this correction, as will be described later.

  Note that the disturbance frequency on the horizontal axis in FIGS. 3 and 4 is the frequency of disturbance vibration. It is known that the frequency of disturbance vibration such as torque ripple, cogging torque and gear pulsation is proportional to the rotational speed of the motor (or the rotational speed of the steering wheel). Therefore, if the rotational speed signal Sn is multiplied by a gain by a conversion constant, a disturbance frequency (ripple frequency) is obtained. This processing is performed by the disturbance frequency conversion means 23. However, if there is an error in this proportional relationship, it cannot be converted by a gain multiplication by a simple constant. In that case, the error may be corrected using a separately prepared map or the like.

  The disturbance frequency conversion process can be included in the BPF frequency map 15 and the BPF gain map 16 without providing the disturbance frequency conversion means 23 as shown in FIG. For example, the horizontal axis of these maps may be converted into the rotation speed signal Sn in advance. However, when a map is used for the disturbance frequency conversion means 23, it is necessary to perform an equivalent conversion from a two-stage map to a single stage.

  BPF has a steep characteristic as shown by a thick line in FIG. It is preferable to use a BPF having a steep characteristic as shown by a thick line rather than a normal multiple root type BPF as shown by a thin line in FIG. 2 because the influence on frequencies other than the center frequency can be suppressed. Note that the vibration extraction filter 8 of the present embodiment is composed of a vibration extraction filter that uses this BPF in two stages in series. When written as an expression, the following expression is obtained. Since there are two steps, the square brackets are squared.

  Here, ζ may be set in a range of approximately 0.05 to 1, and ζ = 0.2 in FIG. When ζ = 1, a normal double root type BPF composed of LPF and HPF is obtained. K1 is provided to correct the decrease in gain at the center frequency fbpf, and the gain (Magnitude) may be set to 0 dB at the center frequency as shown in FIG.

  Next, a part related to current control will be described. The current detection means 6 detects the current Id given to the motor 5 by the drive circuit 4. Next, the target current It calculated by the assist map 20 by the current control means 3 and the current Id detected by the current detection means 6 are controlled to coincide with each other. For example, as a voltage command signal Sv such as a PWM signal, For example, the signal is output to the drive circuit 4 composed of an H-bridge circuit or an inverter circuit, whereby the drive circuit 4 outputs a drive current corresponding to the PWM signal to the motor 5. Thereby, the motor 5 generates assist torque that assists the steering force of the steering shaft by the driver.

  The blocks constituting the control device shown in FIG. 1 are not all configured by hardware, but the output torque signal τ0 of the torque sensor 1, the signal ωm detected by the rotation speed detecting means 7, and the current detection. The configuration from the current Id detected by the means 6 to the calculation of the target current It or the configuration up to the voltage command signal Sv is configured by software using a microcomputer (computer). The microcomputer consists of a well-known central processing unit (CPU), read-only memory (ROM), random access memory (RAM), interface (IF), etc. And a predetermined control operation is performed by executing software, for example, by temporarily storing the calculation result in the RAM.

  As described above, in the present embodiment, the BPF frequency map 15 can be used to set the BPF center frequency with a value corrected from the disturbance frequency (ripple frequency). For example, as shown in FIG. 3, when the disturbance frequency is 60 Hz, the BPF center frequency is set to 80 Hz. In FIG. 5, the effect of suppressing the disturbance vibration according to the present embodiment is expressed by disturbance transfer characteristics. In the case where the BPF center frequency is set equal to the disturbance frequency to 60 Hz as in the prior art (thin broken line fbpf = 60 [Hz] in the figure), this is not reduced because there is no disturbance compensation command. It can be understood that the disturbance suppression effect at 60 Hz is improved in the characteristic proposed in (bold solid line fbpf = 80 [Hz] in the figure). This is because, as shown in FIG. 2, there is a phase advance effect on the lower frequency side than the center frequency of the BPF. If this effect is used, a phase advance compensator is newly added in series with the BPF as in Patent Document 1. The best effect can be obtained with a light calculation load. Further, here, referring to the disturbance transfer characteristics, the BPF center frequency is set so that the region where the maximum effect is obtained, that is, the place where the disturbance transfer characteristics take the minimum value substantially coincides with the disturbance frequency. The characteristics including the effect can be optimized, and as a result, the optimum disturbance suppressing effect is obtained.

  Note that the disturbance transmission characteristic as shown in FIG. 5 is from disturbance torque applied to a steering shaft (not shown) on which the motor 5 is mounted to torque on the steering wheel gripped by the driver, that is, torque felt by the driver. It is a frequency characteristic which shows the gain of transmission. This characteristic varies depending on the mechanism and motor of the electric power steering apparatus, but generally has a tendency as shown in this figure.

  Further, as described above, the BPF gain map 16 is used to set the BPF gain Kbpf that is the vibration suppression control gain, so that the gain can be corrected to an appropriate value according to the disturbance frequency. For example, as shown in FIGS. 6 and 7, when the disturbance frequency is around 30 Hz, the gain can be reduced, and a stability margin against oscillation vibration at the oscillation frequency of the control loop by the assist map 20 can be secured. If the BPF gain Kbpf is set to a large value equal to 20 Hz (thick solid line fbpf = 33 [Hz], Kbpf = 1.3 in FIGS. 6 and 7), Kbpf = 1 as shown in FIG. It can be seen that a large gain of .3 has a greater disturbance suppression effect, but in the open loop circuit transfer function shown in FIG. 7, the phase margin, which is a general stability margin index, is greatly reduced, and oscillation oscillation is reduced. It can be seen that it may occur. On the other hand, the proposed characteristics (thin solid line fbpf = 33 [Hz], Kbpf = 0.6) are more phase margin than the original characteristics without the disturbance compensation command (thin thick dotted line: no disturbance compensation command (Trc = 0)). Is slightly reduced, but is within an acceptable range as a stability margin.

  Therefore, it is desirable to reduce the BPF gain Kbpf near 30 Hz, as shown in FIG. On the other hand, in the vicinity of 60 Hz, the above-described phase advance effect can be expected even for the oscillation frequency (in the vicinity of 45 Hz in FIG. 7), so that the BPF gain Kbpf can be made larger than the disturbance frequency near 30 Hz. The suppression effect can be improved as much as possible. Thus, by appropriately setting the gain for each frequency using the BPF gain map 16, disturbance vibration can be effectively reduced while being compatible with other vibrations such as oscillation vibration.

  FIG. 8 shows the overall image of the disturbance suppression effect realized by this embodiment in the disturbance transfer characteristics. In FIG. 8, the thickest broken line indicates the disturbance transfer characteristic according to the present embodiment. Curves connecting points at each frequency of the characteristics obtained by setting the optimum filter frequency and vibration suppression control gain for each frequency of disturbance frequency (the thickest broken line in the figure: with disturbance compensation command) However, it becomes the disturbance transfer characteristic with respect to the target disturbance by control of this Embodiment. With the above-described configuration, since the BPF gain and the center frequency are optimized for each frequency, a high disturbance suppressing effect can be obtained.

  As described above, according to the first embodiment, vibration (disturbance vibration) due to disturbance such as torque ripple generated by the motor, cogging torque, and pulsation generated in synchronization with gear teeth is suppressed, and the driver's Feeling can be improved.

  In the above example, the disturbance frequency signal is calculated based on the rotational speed of the motor 5, but the same effect can be obtained by using the steering angular speed of the steering wheel instead. This is because there is almost no difference in phase characteristics at a low frequency corresponding to the steering frequency between them, and only the steering frequency is required for calculating the disturbance frequency.

  Although the compensation command is added to the steering torque signal Tsp, the same effect can be obtained by adding it to the target current. However, in that case, it is necessary to correct the compensation command with a gain corresponding to the assist map.

  The saturation process 19 has an effect of reducing the influence on steering by removing a large steering component not related to the vibration component.

  As described above, the electric power steering control device according to this embodiment includes the assist map 20 that calculates the target current It based on the steering torque signal Tsp obtained by detecting the steering torque τ0 applied to the steering wheel by the driver, Based on the target current It, the current control means 3 for controlling the current flowing through the motor 5 and the vibration extraction filter for outputting the vibration component signal Sb by filtering the steering torque signal Tsp or the rotation angle or rotation speed of the motor 5 8, a BPF gain 9 that calculates a BPF compensation command Tb that is a disturbance compensation command based on the vibration component signal Sb, and a filter frequency that corrects the filter frequency of the vibration extraction filter 8 based on the rotational speed of the motor 5 or the steering wheel. And a BPF frequency map 15 as a correction means. Adding or subtracting the signal disturbance compensation command Trc with respect to the torque signal Tsp or target current It, as a new steering torque signal Tsp or target current It, and to perform the processing by the assist map 20 or the current control means. As a result, a value obtained by correcting the disturbance frequency converted from the rotational speed using a correction means such as the BPF frequency map 15 is used as a filter frequency, and the filter frequency is optimized so that the disturbance transfer characteristic is optimized at this time. Can be optimized, so that the effect of suppressing disturbance can be improved. In addition, since the phase characteristic of the vibration extraction filter 8 can be used, the suppression effect can be improved without newly providing a position complementary award device.

  Further, if the BPF frequency map 15 serving as the filter frequency correction means sets the filter frequency so that the portion where the disturbance transfer characteristic takes the minimum value substantially matches the disturbance frequency, the above effect is optimized, The disturbance suppression effect is optimized.

  Further, according to the present embodiment, since the BPF gain map 16 is further provided as a control gain correction means for correcting the BPF gain 9 that is a vibration suppression control gain based on the rotational speed of the motor 5 or the steering wheel. By appropriately setting the gain for each frequency, disturbance vibrations can be effectively reduced while being compatible with other vibrations such as oscillation vibrations.

  Further, according to the present embodiment, the BPF gain map 16 is corrected so as to reduce the BPF gain 9 that is the vibration suppression control gain in the vicinity of the oscillation frequency of the control loop based on the assist map 20. By properly setting the gain, it is possible to optimize the effect that the disturbance vibration can be effectively reduced while being compatible with other vibrations such as oscillation vibration, and the disturbance suppression effect is optimized. .

Embodiment 2. FIG.
FIG. 9 is a block diagram showing a configuration of an electric power steering control apparatus according to Embodiment 2 of the present invention. The configuration of the present embodiment shown in FIG. 9 is the same as that of the first embodiment shown in FIG. 1, but further includes a high-pass filter (HPF) 11, lead compensation gain 12, HPF frequency map 17, and HPF gain map. 18 and the adder 13 are added, and the configuration is the same as that of the first embodiment except for these additional portions. Accordingly, the same components are denoted by the same reference numerals, and description thereof is omitted here. In addition, since operations other than those described below are the same as those in the first embodiment, description thereof is also omitted here. These additional portions 11, 12, 13, 17, and 18 are referred to as HPF compensation blocks. However, in the present embodiment, the BPF frequency map 15 and the BPF gain map 16 are changed as shown in FIGS.

  By filtering the steering torque signal Tsp by the high-pass filter 11, a steering component, a noise component, and the like are reduced from the steering torque signal Tsp, and a advance component signal Sh that gives a phase advance effect to the steering torque signal Tsp is output. The configuration method of the high-pass filter 11 may be a normal one represented by s / (s + 2 · π · fhpf), and in this embodiment, two stages are provided in series.

  An HPF compensation command Th is calculated by multiplying the advance component signal Sh filtered by the high pass filter 11 by an HPF gain (Khpf) 12 that is an advance compensation gain. Next, the adder 13 adds the BPF compensation command Tb obtained by multiplying the vibration component signal Sb output from the vibration extraction filter 8 by the BPF gain 9 as described in the first embodiment to the HPF compensation command Th. Is saturated by the saturation means 19 to generate a disturbance compensation command Trc. The HPF filter frequency (cutoff frequency) and HPF gain are configured to be variable based on the rotational speed of the motor as follows.

  The disturbance frequency signal fd from the disturbance frequency conversion means 23 is input to the HPF frequency map 17 and the HPF gain map 18, and the HPF cutoff frequency fhpf and the HPF gain Khpf are respectively shown in accordance with the characteristics shown in FIGS. Is calculated. The calculated HPF cutoff frequency fhpf is set as the cutoff frequency fhpf of the high-pass filter 11. Further, the calculated HPF gain Khpf is multiplied by the advance component signal Sh as the HPF gain to calculate the HPF compensation command Th. The HPF frequency map 17 can be said to be a high-pass filter frequency correction unit that corrects the cutoff frequency of the high-pass filter 11 based on the disturbance frequency. Further, the HPF gain map 18 can be said to be advance compensation gain correction means for correcting the HPF gain (Khpf) 9 as the advance compensation gain based on the disturbance frequency.

  The disturbance frequency on the horizontal axis in FIGS. 12 and 13 is the frequency of disturbance vibration, and the frequency of disturbance vibration such as torque ripple, cogging torque, and gear pulsation may be proportional to the rotational speed of the motor. Are known. Therefore, if the rotational speed signal Sn is multiplied by a gain by a conversion constant, a disturbance frequency (ripple frequency) is obtained. This processing is performed by the disturbance frequency conversion means 23. However, if there is an error in this proportional relationship, it cannot be converted by gain multiplication by a simple constant. In that case, the error may be corrected using a separate map or the like. Further, this conversion process can be included in the HPF frequency map 17 and the HPF gain map 18 without providing the disturbance frequency conversion means 23 as shown in FIG. For example, the horizontal axis of these maps may be converted into the rotation speed signal Sn in advance.

  Note that the high-pass filter 11 is generally required to have a HPF characteristic, that is, a characteristic that lowers the gain characteristic in the low frequency range, and can provide low-frequency elimination and a phase advance effect. For example, the differential or the differential slightly subjected to LPF, or the HPF subjected to phase compensation may be used.

  According to the present embodiment, the following effects can be obtained.

  In the case where there is no HPF compensation block as in the first embodiment, the BPF gain cannot be increased because the phase margin of the open loop circuit transfer function is reduced, and a sufficient disturbance suppression effect cannot be obtained. 14 is a disturbance transmission characteristic as shown by a thin solid line (fbpf = 33 [Hz], Kbpf = 0.6, no HPF compensation) in FIG. 14A, but according to the present embodiment, the thin line is thin. As shown by the broken line (fbpf = 33 [Hz], Kbpf = 1.3, with HPF compensation), a sufficient disturbance suppressing effect can be obtained. This is because the phase advance effect is obtained by the HPF compensation block, so that a sufficient phase margin can be secured even if the BPF gain is increased more than twice as in the open-loop circuit transfer function shown in FIG. Because. That is, it is possible to sufficiently obtain the disturbance suppressing effect while reducing the influence of the assist map 20 on the stability of the control loop and suppressing the oscillation.

  FIG. 14A is an example of disturbance transmission characteristics in the present embodiment, and shows the effect of suppressing disturbance vibration according to the present invention. It represents the case when the disturbance vibration is 30 Hz. FIG. 14B shows an open-loop circuit transfer function in the present embodiment. It represents the case when the disturbance vibration is 30 Hz.

  Further, as another effect of the HPF compensation block, there is a disturbance suppressing effect in itself. For example, as shown in FIG. 11, the BPF gain of the present embodiment is intentionally set small in the vicinity of the disturbance frequency of 60 Hz, so that the disturbance suppressing effect by the BPF is not expected. On the other hand, the HPF gain shown in FIG. 13 has a large value around the disturbance frequency of 60 Hz, and aims at the disturbance suppressing effect by the HPF compensation block. The effect is shown in FIG. 15 as disturbance transfer characteristics. In FIG. 15, the thickest broken line indicates the disturbance transfer characteristic according to the present embodiment. According to the disturbance transfer characteristics shown in FIG. 15, the thin and thick broken line (no disturbance compensation command (no disturbance compensation command), which is a characteristic when the disturbance compensation command is invalidated in the vicinity of 60 Hz of the dark thin broken line (when dealing with 60 Hz disturbance) in the figure. It can be seen that it is sufficiently reduced as compared with Trc = 0)). Compared with FIG. 8 showing the effect of the first embodiment having a configuration without an HPF compensation block, an improvement in suppression effect of about −3 dB can be seen. This indicates that the disturbance suppression effect can be improved by the phase advance effect by the HPF compensation block.

  Thus, according to the second embodiment, vibration (disturbance vibration) due to disturbance such as torque ripple and cogging torque generated by the motor 5 and pulsation generated in synchronization with gear teeth is suppressed, and the driver The feeling can be greatly improved.

  According to the second embodiment, the high-pass filter 11 that outputs the advance component signal that gives the low frequency removal effect and the phase advance effect to the steering torque signal Tsp or the rotation angle or rotation speed of the motor 5, and the advance component signal And a lead compensation gain 12 for calculating a lead compensation command based on the above, and a value obtained by adding the lead compensation command Th to the disturbance compensation command Trc as a new disturbance compensation command. Therefore, the variable BPF gain can be increased, and the disturbance suppressing effect can be improved. Moreover, the disturbance suppression effect can be improved also by HPF itself.

  In the present embodiment, the HPF frequency map 17 which is high-pass filter frequency correction means for correcting the filter frequency of the high-pass filter 11 based on the rotational speed of the motor 5 or the steering wheel, and the rotational speed of the motor 5 or the steering wheel. Since the HPF gain map 18 which is a lead compensation gain correction means for correcting the HPF gain 9 which is the lead compensation gain is provided based on the HPF, the HPF can be optimized in cooperation with the BPF for each frequency. The disturbance suppressing effect can be improved.

Embodiment 3 FIG.
FIG. 16 is a block diagram showing a configuration of a control apparatus according to Embodiment 3 of the present invention. In FIG. 16, 7b is a rotation angle detecting means, 22 is an angle HPF, 24 is a differentiating means, and 30 is a subtractor.

  In the above-described second embodiment, the control process for applying the vibration extraction filter 8 and the high-pass filter 11 to suppress the disturbance vibration is described with respect to the steering torque signal Tsp. The vibration extraction filter 8 and the high-pass filter 11 are applied to the signal based on the rotation angle or the rotation speed.

  The difference between the present embodiment and the second embodiment is that, in this embodiment, a rotation angle detection means 7b is provided instead of the rotation speed detection means 7 of FIG. The rotation signal Sf output from the angle HPF 22 provided at the subsequent stage of the rotation angle detection means 7b, instead of the steering torque signal Tsp, at the point where the differentiation means 24 is inserted in the previous stage, and the vibration extraction filter 8 and the high-pass filter 11. And a subtracter 30 in place of the adder 10 in FIG.

  Therefore, in the present embodiment, the signal input to the vibration extraction filter 8 and the high-pass filter 11 is changed from the steering torque signal Tsp to the rotation signal Sf, and means for generating the rotation signal Sf (that is, rotation angle detection) Except for providing the means 7b and the angle HPF22), replacing the adder 10 with the subtractor 30, and providing the differentiating means 24 for obtaining the rotational speed, the steering torque is the same as that of the second embodiment. Except for the operation of subtracting the disturbance compensation command Trc from the signal Tsp and the following operation, the same operation as in the second embodiment is performed. However, the magnitudes of the BPF gain (vibration suppression control gain) 9 and the HPF gain (lead compensation gain) 12 are changed by the change in the signal level due to the change in the steering torque signal Tsp to the rotation angle or rotation speed signal. And

  The changed part will be described. The rotation angle detection means 7b detects the rotation angle of the motor 5 and outputs a rotation angle signal θm. The differentiating means 24 performs an operation such as differentiation or approximate differentiation on the rotation angle signal θm, and calculates the rotation speed detection signal ωm. This is input to the LPF 14. Further, the rotation angle signal θm is subjected to high-pass filter processing having a high-frequency pass characteristic at the angle HPF 22 to generate a rotation signal Sf. This rotation signal Sf is input to the vibration extraction filter 8 and the high-pass filter 11. The processing from the processing by the LPF 14, the vibration extraction filter 8 and the high-pass filter 11 to the calculation of the disturbance compensation command Trc is the same as that in the second embodiment. However, as described above, the magnitudes of the BPF gain 9 and the HPF gain 12 are changed by the change in the signal level due to the change of the signal.

  The angle HPF 22 may be a normal one represented by s / (s + 2 · π · fc). fc may be about 5 to 20 Hz.

  In the electric power steering, the rotation angle of the motor 5 and the steering torque τ0 have the same response characteristics except for the low frequency. However, the sign is reversed. This is because there is a relationship of steering torque τ 0 = Kts · (θh−θm) where the elastic coefficient of the torque sensor 1 is Kts. Here, θh is the rotation angle of the steering wheel. Since θh hardly responds at a frequency higher than about 5 to 20 Hz, it becomes a value close to zero. Therefore, the steering torque signal Tsp and the rotation angle signal θm of the motor 5 are substantially in opposite signs and have a gain multiplication relationship except for low frequencies. The characteristics of the low frequency are different, and the rotation angle has a relatively large response, but this is a steering component and hardly includes disturbance vibration components. Therefore, it is sufficient to reduce the low frequency at the angle HPF. .

  Therefore, in the present embodiment, the magnitudes of the BPF gain 9 and the HPF gain 12 are approximately multiplied by Kts, and the adder 10 of the second embodiment is changed to the subtractor 30 to change the steering torque signal Tsp. By changing so that the disturbance compensation command Trc is subtracted from the control, the same control as in the second embodiment can be realized.

  Therefore, according to the third embodiment, the same effects as those of the first and second embodiments can be obtained. Therefore, torque ripple and cogging torque generated by the motor 5, pulsation generated in synchronization with gear teeth, etc. The vibration (disturbance vibration) due to the external disturbance can be suppressed, and the driver's feeling can be greatly improved.

  Although the rotation signal Sf is obtained from the angle HPF 22 in the above configuration, the rotation speed detection signal ωm that is the output of the differentiating means 24 may be substituted for the rotation signal Sf. Alternatively, instead of the rotation angle detection means 7b, the rotation speed detection means 7 may be provided, and the rotation speed detection signal ωm that is the output thereof may be used as the rotation signal Sf. This is because the signal obtained by advancing the phase of the rotation angle signal is the rotation speed signal, so that the disturbance vibration suppression effect by this advance can be aimed at. However, in this case, since the signal level changes, the BPF gain map 16 and the HPF gain map 18 are readjusted. As a result, an effect equivalent to that of the above-described configuration in which the rotation signal Sf is obtained from the angle HPF 22 can be obtained.

  Further, in order to reduce high-frequency noise, a signal obtained by subjecting the rotation speed detection signal ωm to low-pass filtering may be used as the rotation signal Sf. In this case, the same effect as the above configuration can be obtained.

  If the HPF compensation block is eliminated, only the effect relating to the vibration extraction filter (BPF) is obtained, and thus the same effect as in the first embodiment is obtained.

Embodiment 4 FIG.
FIG. 17 is a block diagram showing a configuration of an electric power steering control apparatus according to Embodiment 4 of the present invention. The configuration of the present embodiment is a configuration in which a switchback detection unit 21 is added to the above-described second embodiment, and the second embodiment is the same as the second embodiment except for this additional portion and the accompanying change in the BPF gain map and HPF gain map. The configuration is the same as that of the second embodiment except for the operations described below.

  The switching detection unit 21 receives the rotation speed signal Sn output from the LPF 14 and outputs a weighting coefficient w. A method for obtaining the weight coefficient w will be described later. The weighting factor w generated in this way is transferred to the BPF gain map 16 and the HPF gain map 18, where the gain is corrected based on the weighting factor w, and the corrected BPF gain Kbpf and HPF gain Khpf are output. The

  Next, the operation of the return detection unit 21 will be described with reference to FIGS. First, in step S01 in FIG. 18, it is determined whether or not the sign of the rotation speed signal Sn is reversed. If the sign is reversed, a trapezoidal wave as shown in FIG. A value according to the wave is substituted into the weighting factor w. Note that the trapezoidal wave time Tw in FIG. 19 may be set approximately between 0 and 1 second after the time when the sign inversion of the rotational speed signal Sn is detected (turnback). Further, the time required for the rising and falling of the trapezoidal wave is set to a minute time width with respect to the time Tw. As shown in FIG. 19, the trapezoidal wave has w = 0 until the time when Sn sign inversion is detected, the value of w gradually increases from the detected time, and after the rise, w = 1. It becomes. After that, during a predetermined time (<Tw), w = 1 is maintained. After that, the value of w starts to gradually decrease and becomes w = 0 when the falling is completed. On the other hand, if the sign of the rotation speed signal Sn is not reversed in the determination in step S01, zero is substituted for the weighting coefficient w in step S03. Next, in step S04, the weighting coefficient w obtained in step S02 or S03 is output.

  Using the weighting factor w generated in this manner, the BPF gain Kbpf and the HPF gain Khpf are corrected in the BPF gain map 16 and the HPF gain map 18, respectively. For example, the correction is made as follows. In the following formula, k is a value between 0 and 1.

Kbpf (after correction) = (1−k · w) · Kbpf (before correction)
Khpf (after correction) = (1 + k · w) · Khpf (before correction)

  As a result, the corrected BPF gain Kbpf (after correction) and the HPF gain Khpf (after correction) are not corrected from the gain before correction when the weighting coefficient w is zero, and remain as they are. When w is 1, they are multiplied by (1−k · w) and (1 + k · w), respectively. When the weighting factor w is an intermediate value between 0 and 1, the corrected gain is also an intermediate value corresponding to the gain.

  That is, when the reversal of the rotation direction of the steering, which is called turning, is detected, the BPF gain is reduced and the HPF gain is increased only for a certain period.

  As another configuration that performs the same operation, a correction gain map that functions when the weighting coefficient is greater than zero is provided as a correction BPF gain map and a correction HPF gain map, respectively. The gain Kbpf (for correction) and the correction HPF gain Khpf (for correction) are used as the following equation.

Kbpf (after correction) = (1-w) · Kbpf (before correction) + w · Kbpf (for correction)
Khpf (after correction) = (1-w) · Khpf (before correction) + w · Khpf (for correction)

  If Kbpf (for correction) is set smaller than Kbpf (before correction) and Khpf (for correction) is set larger than Khpf (before correction), the same operation as the method described above can be realized.

  Immediately after the turning of the steering, there is a case where characteristic changes such as gears greatly change and specific vibrations are generated. In such a case, according to the configuration as described above, the BPF gain can be reduced only immediately after turning back, so that disturbance vibration is suppressed during normal steering without affecting the vibration during turning. You can get the effect you want.

  Unlike the BPF, the HPF compensation block has an effect of suppressing vibrations in a wide frequency band. Therefore, while reducing the BPF gain, the HPF gain is increased instead to compensate for the disturbance suppressing effect. Therefore, the disturbance suppressing effect is maintained well even immediately after switching.

  Therefore, according to the fourth embodiment, the vibration (disturbance vibration) due to disturbance such as torque ripple and cogging torque generated by the motor and pulsation generated in synchronization with the gear teeth is suppressed, and the driver's feeling is improved. It can be greatly improved.

  As a modification of this embodiment, there is a configuration in which the weighting coefficient w is determined based on the current Id and the rated current Imax of the motor 5. For example, the weighting coefficient w = | Id | / Imax is defined by the relational expression. Then, when the absolute value of the current Id is zero, the weighting factor w is also zero, and when the absolute value of the current Id is the maximum value Imax, the weighting factor w is 1. The weighting factor w is proportional to the absolute value of the current Id.

  Based on this weighting factor w, correction in each gain map is performed by the following equation.

Kbpf (after correction) = w · Kbpf (before correction)
Khpf (after correction) = w · Khpf (before correction)

  According to this, when the absolute value of the current Id is small, the BPF gain and the HPF gain are corrected to be small, and when the absolute value of the current Id is large, the BPF gain and the HPF gain are large.

  It is known that the magnitude of disturbance such as torque ripple generated by a motor increases depending on the current. Therefore, according to the configuration of such a modified example, since the BPF gain and the HPF gain are increased in a region where the disturbance is large, the effect of suppressing the disturbance is enhanced. On the contrary, in the region where the disturbance is small, the gain is decreased. Therefore, the magnitude of the disturbance compensation command can be minimized. That is, disturbance vibration can be efficiently suppressed while minimizing the compensation command.

  Since the current Id is generally proportional to the steering torque signal due to the tendency of the assist map, when the weighting factor w is calculated, a value obtained by multiplying the steering torque signal by a constant is used instead of the current Id. However, the same effect can be obtained.

  In this embodiment, the steering torque signal is input to the vibration extraction filter 8 and the high-pass filter 11. However, as in the third embodiment, the present embodiment may be configured with the rotation signal Sf. The additional part by is obviously applicable, and the same effect can be obtained.

  As described above, in the present embodiment, the reversal detection unit 21 that detects the reversal of the steering direction and outputs the weighting coefficient w is provided. In the BPF gain map 16 that is the control gain correction means, the weighting coefficient w and the motor Since the BPF gain 9, which is a vibration suppression control gain, is corrected according to the rotation speed of 5, disturbance vibrations can be effectively reduced while being compatible with other vibrations such as switching.

  In the present embodiment, the BPF gain map 16 that is the control gain correction means corrects the BPF gain 9 that is the vibration suppression control gain according to the current and the rotational speed. Accordingly, the gain can be increased and decreased to effectively reduce disturbance vibration.

  Further, in the present embodiment, there is provided a switching detection unit 21 that detects the reversal of the steering direction and outputs the weighting factor w. In the HPF gain map 18 that is the advance compensation gain correction means, the weighting factor w and the motor 5 Since the HPF gain, which is the lead compensation gain, is corrected in accordance with the rotation speed, disturbance vibration can be effectively reduced while being compatible with other vibrations such as turning back.

  Further, in the present embodiment, the HPF gain map 18 that is the advance compensation gain correction means corrects the HPF gain that is the advance compensation gain in accordance with the current and rotation speed of the motor 5, so that disturbance vibration According to the magnitude of the gain, the gain can be increased or decreased to effectively reduce disturbance vibration.

  DESCRIPTION OF SYMBOLS 1 Torque sensor, 2 Phase compensator, 3 Current control means, 4 Drive circuit, 5 Motor, 6 Current detection means, 7 Rotational speed detection means, 7b Rotation angle detection means, 8 Vibration extraction filter, 9 Vibration suppression control gain (BPF) Gain), 10 adder, 11 high pass filter (HPF), 12 lead compensation gain (HPF gain), 13 adder, 14 low pass filter (LPF), 15 BPF frequency map (filter frequency correction means), 16 BPF gain map ( Control gain correction means), 17 HPF frequency map (high pass filter frequency correction means), 18 HPF gain map (advance compensation gain correction means), 19 saturation means, 20 assist map, 21 switching back detection section, 22 angle HPF, 23 disturbance frequency Conversion means, 24 differentiation means, 30 subtractor.

Claims (10)

An assist map for calculating a target current based on a detected steering torque signal indicating a steering torque applied to the steering wheel;
Current control means for controlling the current flowing through the motor based on the target current;
A vibration extraction filter that outputs a vibration component signal by filtering the steering torque signal or the rotation angle or rotation speed of the motor;
A vibration suppression control gain that calculates a disturbance compensation command based on the vibration component signal;
Filter frequency correction means for correcting the filter frequency of the vibration extraction filter based on the rotational speed of the motor or the steering wheel;
Electric power characterized in that processing by the assist map or the current control means is performed using a signal obtained by adding or subtracting the disturbance compensation command to the steering torque signal or the target current as a new steering torque signal or target current. Steering control device. 2. The electric power steering control device according to claim 1, wherein the filter frequency correction unit sets the filter frequency so that a portion where the disturbance transfer characteristic takes a minimum value substantially matches the disturbance frequency. The electric power steering control device according to claim 1, further comprising control gain correction means for correcting the vibration suppression control gain based on a rotation speed of a motor or a steering wheel. The electric power steering control device according to claim 3, wherein the control gain correction unit corrects the vibration suppression control gain to decrease in the vicinity of an oscillation frequency of a control loop based on an assist map. A high-pass filter that outputs a lead component signal that gives a low frequency removal effect and a phase advance effect to the steering torque signal or the rotation angle or rotation speed of the motor;
A lead compensation gain for calculating a lead compensation command based on the lead component signal, and
The electric power steering control device according to claim 1, wherein a value obtained by adding the advance compensation command to the disturbance compensation command is newly set as a disturbance compensation command. High-pass filter frequency correction means for correcting the filter frequency of the high-pass filter based on the rotational speed of the motor or steering wheel;
6. The electric power steering control device according to claim 5, further comprising a lead compensation gain correcting means for correcting the lead compensation gain based on a rotational speed of a motor or a steering wheel. A turn-back detection unit that detects the reversal of the steering direction and outputs a weighting coefficient,
The electric power steering control device according to claim 3, wherein the control gain correction unit corrects the vibration suppression control gain according to the weighting factor and the rotation speed. The electric power steering control device according to claim 3, wherein the control gain correction means corrects the vibration suppression control gain according to the current and the rotation speed. A turn-back detection unit that detects the reversal of the steering direction and outputs a weighting coefficient,
The electric power steering control device according to claim 6, wherein the advance compensation gain correction means corrects the advance compensation gain in accordance with the weighting factor and the rotation speed. The electric power steering control device according to claim 3, wherein the advance compensation gain correction means corrects the advance compensation gain according to the current and the rotation speed.

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