Motor control device
The motor control device addresses torque ripple vibrations in systems like electric power steering by using a disturbance observer to estimate and compensate for disturbances, enhancing motor responsiveness and reducing vibrations for a smoother operation.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2022-03-16
- Publication Date
- 2026-04-01
AI Technical Summary
Existing motor control systems, such as electric power steering systems, struggle to effectively suppress torque ripple vibrations, which are transmitted to the steering wheel, and this issue is not adequately addressed by conventional torque derivative control methods.
A motor control device that includes a disturbance observer unit to estimate and compensate for disturbances based on motor rotation information, adjusting parameters to suppress vibrations with specific frequency characteristics, and a compensator to improve motor responsiveness and reduce torque fluctuations.
The device effectively suppresses torque ripple vibrations and improves motor responsiveness, providing a smoother steering experience by precisely compensating for disturbances across a wide frequency range and reducing torque fluctuations.
Smart Images
Figure 0007838633000001 
Figure 0007838633000002 
Figure 0007838633000003
Abstract
Description
[Technical Field]
[0001] This invention relates to a motor control device. [Background technology]
[0002] Conventionally, electric power steering systems exist. An electric power steering system (hereinafter referred to as "EPS") assists steering the steering wheel by applying motor torque to the steering mechanism. The EPS control unit calculates a target current value according to the steering torque applied to the steering wheel and controls the power supply to the motor based on the calculated target current value. As a result, the motor generates torque corresponding to the steering torque.
[0003] In EPS (Electric Power Steering), vibrations caused by torque ripple in the motor or reducer are easily transmitted to the steering wheel. Therefore, torque derivative control, such as that described in Patent Document 1, is employed. The control device calculates a torque derivative value by differentiating the steering torque detected by the torque sensor, and corrects the target current value according to the calculated torque derivative value. This suppresses vibrations caused by torque ripple. [Prior art documents] [Patent Documents]
[0004] [Patent Document 1] Japanese Patent Publication No. 2004-224129 [Overview of the project] [Problems that the invention aims to solve]
[0005] While torque differential control can certainly suppress vibrations caused by torque ripple, it may not be able to suppress these vibrations to the required level. Therefore, a more appropriate method for suppressing torque ripple vibrations is needed. Furthermore, motors are used as drive sources for various mechanical devices, not just electric power steering systems. These mechanical devices also require reduced torque ripple vibrations. [Means for solving the problem]
[0006] A motor control device according to one aspect of the present disclosure controls a motor of a mechanical device. The motor control device includes a command value calculation unit configured to calculate a command value for controlling the motor, and a disturbance observer unit configured to estimate disturbances applied to the mechanical device based on the command value and rotation information of the motor, and to correct the command value based on the estimated disturbance. The disturbance observer unit has parameters that are adjusted to compensate for the effects of disturbances having a specific frequency to be suppressed. The disturbance applied to the mechanical device after the effects of the disturbance have been compensated is the post-compensated disturbance, and the parameters are adjusted so that the disturbance after compensation has frequency characteristics corresponding to the anti-resonance characteristics of the mechanical device. The disturbance observer unit is configured to change the values of the parameters in accordance with the rotation information of the motor. [Brief explanation of the drawing]
[0007] [Figure 1] A diagram illustrating the configuration of one embodiment of a motor control device. [Figure 2] Block diagram of the motor control device shown in Figure 1. [Figure 3] A graph showing the frequency characteristics of the disturbance. [Modes for carrying out the invention]
[0008] <First Embodiment> A motor control device 11 according to the first embodiment will be described. As shown in Figure 1, the motor control device 11 controls the motor 12. The motor 12 generates torque to drive the mechanical device 13 on which the motor 12 is mounted. The motor 12 is, for example, a three-phase brushless motor. The motor 12 has a rotation angle sensor 12A. The rotation angle sensor 12A detects the rotation angle θ of the motor 12. The rotation angle θ of the motor 12 is the rotation information of the motor 12.
[0009] The motor control device 11 includes a microcomputer 21, an inverter 22, and a current sensor 23. The processing circuit, the microcomputer 21, includes a command value calculation unit 31 and a feedback calculation unit 32. These calculation units are functional parts realized by the CPU (Central Processing Unit) of the microcomputer 21 executing a control program. The microcomputer 21 includes memory for storing the control program. The memory includes computer-readable media such as RAM (Random Access Memory) and ROM (Read Only Memory). However, while each calculation unit may be implemented by software, at least some of the calculation units may be implemented by hardware circuits such as logic circuits.
[0010] The command value calculation unit 31 calculates a state variable S that indicates the state of the machine device 13, for example. sv Based on this, the current command value I for motor 12 * The feedback calculation unit 32 calculates the current command value I calculated by the command value calculation unit 31. * The difference between the current command value I and the value of the motor 12 current Im detected through the current sensor 23 is calculated. The feedback calculation unit 32 calculates the difference between the current command value I * A drive signal is generated for the inverter 22 so as to eliminate the difference between the value of the motor 12's current Im and the value of the motor 12's current Im.
[0011] The inverter 22 operates based on the drive signal generated by the feedback operation unit 32. The inverter 22 has a plurality of switching elements. When these switching elements switch based on the drive signal, power corresponding to the current command value I * is generated. The power generated by the inverter 22 is supplied to the motor 12 via a power supply path composed of a bus bar or a cable or the like. Thereby, the motor 12 generates torque corresponding to the current command value I * .
[0012] <Disturbance observer> As shown in the block diagram of FIG. 2, the motor control device 11 has a disturbance observer unit 33. The disturbance observer unit 33 is provided to estimate the disturbance T ld applied to the plant P that is the control target and compensate for the influence of the disturbance T ld . Compensating for the influence of the disturbance means reducing the influence of the disturbance in the control of the system affected by the disturbance, considering the characteristics of the disturbance. The disturbance T ld is a non-linear torque. The disturbance T ld is, for example, the torque ripple of the motor 12. The torque ripple is a disturbance that occurs periodically according to the rotation of the motor 12.
[0013] The control system of the motor 12 is a feedback control system that determines the current command value I sv for the motor 12 based on the state variable S * of the mechanical device 13. When current is supplied from the inverter 22 to the motor 12 according to the current command value I * , the motor 12 rotates at a predetermined angular velocity ω m . Therefore, from the current command value I * for the motor 12 to the angular velocity ω m of the motor 12 are the control targets in the feedback control system. The angular velocity ω m of the motor is the rotation information of the motor 12. The plant P includes the mechanical device 13.
[0014] If the inertia number of the mechanical device 13 is "1" and the mechanical device 13 and the motor 12 are considered to be coupled via an elastic element, the controlled object can be considered as a two-inertia system in which two moments of inertia are coupled by an elastic element. In this case, the controlled object has a frequency characteristic that includes one pair of resonant and anti-resonant characteristics.
[0015] Furthermore, if the inertia number of the mechanical device 13 is "2" and the mechanical device 13 and the motor 12 are considered to be coupled via an elastic element, the controlled object can be considered as a three-inertia system in which three moments of inertia are coupled by an elastic element. In this case, the controlled object has a frequency characteristic that includes two pairs of resonant and anti-resonant characteristics.
[0016] The disturbance observer unit 33 sets the current command value I, which is the target value of plant P. * The output of plant P is then taken in. An example of the output of plant P is the angular velocity ω of motor 12. m Angular velocity ω m This is obtained by differentiating the rotation angle θ of the motor 12 detected by the rotation angle sensor 12A. The disturbance observer unit 33 receives the current command value I * and the angular velocity ω of motor 12 m Based on the disturbance T ld The disturbance observer unit 33 estimates the disturbance T having a frequency to be suppressed. ld First correction value I to cancel out c1 Perform the calculation.
[0017] The disturbance observer unit 33 includes an estimator 33A, a multiplier 33B, and a subtractor 33C. The disturbance observer unit 33 may be composed of hardware circuits such as logic circuits. The disturbance observer unit 33 is also called a disturbance observer circuit. Alternatively, the disturbance observer unit 33 may be a functional part realized by the execution of a control program by the CPU of a computer.
[0018] The estimator 33A has a nominal plant Pn, a first observer gain L1, and a second observer gain L2. The nominal plant Pn is a model that simulates the controlled plant P. The estimator 33A determines the angular velocity ω of the motor 12 obtained as the output of plant P, as shown in equation (1) below. m And the estimated angular velocity ω of motor 12 obtained as the output of nominal plant Pn m Calculate the difference Δω from ^. "^" indicates that it is an estimated value.
[0019] Δω=ω m -ω m ^ …(1) The estimator 33A determines the angular velocity ω of the motor 12, as shown in equation (2) below. m And the estimated angular velocity ω of motor 12 m By multiplying the difference Δω with ^ by the second observer gain L2, the estimated disturbance T is obtained. ld The derivative of ^, dT ld Perform the operation ^.
[0020] dT ld ^=Δω·L2 …(2) Furthermore, the estimator 33A estimates the disturbance T. ld The derivative of ^, dT ld Estimated disturbance T by integrating ^ ld Calculate ^. The nominal plant Pn is the estimated disturbance T. ld The angular velocity ω is calculated using the value obtained by multiplying the difference Δω by the first observer gain L1, and the viscosity coefficient C of the motor 12. m Estimated value of ω m Perform the operation ^.
[0021] The multiplier 33B calculates the estimated disturbance T calculated by the estimator 33A. ld The derivative of ^, dT ld By multiplying ^ by the gain β, the first correction value I is obtained. c1 The first correction value I is calculated. c1 is a disturbance T ld This is the current value required to cancel out the vibrations caused by [the current].
[0022] Subtractor 33C controls the current command value I * From the first correction value I c1 By subtracting the disturbance T, ld Current command value I compensated for the effects * Perform the calculation. Disturbance T is detected by the disturbance observer unit 33 ld The disturbance T applied to the machine 13 after the effects of the disturbance T have been compensated for. ld Compensated disturbance T last That's what they say.
[0023] Compensated disturbance T last This can be expressed by the following equation (3). T last =T ld -β·dT ld ^={Js 2 +(-L2·β+L1·J)s+L2}·T ld / {Js 2 +(-L2·C+L1·J)s+L2}·Js …(3) However, "J" is the inertia coefficient modeling the moment of inertia of the mechanical device 13. "C" is the viscosity coefficient modeling the friction of the mechanical device 13. "s" is the Laplace operator. "L1" is the first observer gain. "L2" is the second observer gain. "β" is the gain.
[0024] As shown in the graph in Figure 3, the compensated disturbance T last It has a notch, which is a spike-shaped dip, in its frequency response. Compensated disturbance T last It has frequency characteristics that correspond to the anti-resonance characteristics of plant P.
[0025] The first observer gain L1 is expressed by the following equation (4). L1 = 2·ω·α …(4) However, "ω" is the frequency, and "α" is the first parameter.
[0026] The second observer gain L2 is expressed by the following equation (5). L2 = J·ω 2 …(5) However, "J" is the inertia coefficient that models the moment of inertia of the mechanical device 13, and "ω" is the frequency.
[0027] The gain β is expressed by the following equation (6). β = α / ω·2·γ …(6) However, "α" is the first parameter, "ω" is the frequency, and "γ" is the second parameter. The second parameter γ is a value less than or equal to "1", and can be set in increments of, for example, "0.1".
[0028] The value of frequency ω is the disturbance T that should be suppressed. ld The frequency is set to T. ld The frequency of is, for example, the disturbance T ld The center frequency f of the notch c That is the case. Furthermore, by adjusting the value of the first observer gain L1, the disturbance T ld The width of the notch in W n It is possible to adjust this. By adjusting the value of the first parameter α in equation (4), it is possible to adjust the value of the first observer gain L1.
[0029] Furthermore, by adjusting the value of the gain β, the disturbance T can be controlled. ld The depth of the notch in D n This can be adjusted. By adjusting the value of the second parameter γ in equation (6), the value of the gain β can be adjusted.
[0030] The first observer gain L1 and gain β are determined by the disturbance T having a specific frequency to be suppressed. ld These are parameters adjusted to suppress vibrations caused by the first observer gain L1 and gain β. ld The transmission ratio can be adjusted. The value of the first observer gain L1 and the gain β are set to the compensated disturbance T lastThe compensated disturbance T is adjusted to have a frequency response corresponding to the anti-resonance characteristics of plant P. last When this is input to plant P, a disturbance T with a specific frequency to be suppressed occurs. ld Theoretically, it is possible to set the amplitude of the vibration of the mechanical device 13 caused by this to "0".
[0031] By substituting equations (4), (5), and (6) into equation (3) above, we obtain equation (7). T last ={s 2 +2·ω·α·(1-γ)·s+ω 2}·T ld / {s 2 +2·ω·α·s+ω 2}…(7) When the value of the second term "2·ω·α·(1-γ)·s" inside the curly braces in the numerator of equation (7) is "0", the disturbance T having a specific frequency to be suppressed is ld The transmission ratio to plant P becomes "0". Therefore, by setting the value of the second parameter γ to "1", the disturbance T with a specific frequency to be suppressed is suppressed. ld The vibrations caused by this can be canceled out. Furthermore, by adjusting the value of the second parameter γ in increments of, for example, 0.1 between 0 and 1, the disturbance T with a specific frequency to be suppressed can be controlled. ld It is possible to adjust the transfer rate to plant P. The smaller the value of the second term "2·ω·α·(1-γ)·s" in the curly braces in the numerator of equation (7), the more the disturbance T with a specific frequency that is to be suppressed is controlled. ld The transfer rate to plant P decreases.
[0032] Note that the second term in curly braces in the numerator of equation (7), "2·ω·α·(1-γ)·s", corresponds to the second term in curly braces in the numerator of equation (3), "(-L2·β+L1·J)s". Adjusting the value of the second parameter γ is also equivalent to adjusting the value of the gain β.
[0033] <Disturbance T ldRegarding the change in frequency> According to the motor control device 11, it is possible to compensate for the influence of the disturbance T having a specific frequency. However, in the motor control device 11, the following is a concern. ld That is, due to the change in the angular velocity ω of the motor 12
[0034] the frequency of the disturbance T m may change. Therefore, when the values of the parameters of the disturbance observer unit 33 are fixed to values specific to a specific frequency, there is a possibility that the influence of the disturbance T ld cannot be appropriately compensated. The parameters are the gain β, the first observer gain L1, and the second observer gain L2. ld Therefore, the disturbance observer unit 33 changes the value of the gain β, the value of the first observer gain L1, and the value of the second observer gain L2 in accordance with the change in the angular velocity ω of the motor 12
[0035] and thus the change in the frequency of the disturbance T m In this case, the gain β is represented by the following equation (8). The first observer gain L1 is represented by the following equation (9). The second observer gain L2 is represented by the following equation (10). ld β = α / ω(t) · 2 · γ …(8)
[0036] L1 = 2 · ω(t) · α …(9) L2 = J · ω(t) 0]…(10) 2 where “t” is time. “ω(t)” is the frequency at time t and can change over time. “α” is the first parameter. “γ” is the second parameter. “J” is the inertia coefficient modeling the moment of inertia of the mechanical device 13. From equations (8) to (10), the following can be understood. That is, the angular velocity ω of the motor 12
[0037] m When it changes, the value of the frequency ω(t) changes. When the value of the frequency ω(t) changes, the values of the gain β, the first observer gain L1, and the second observer gain L2 change according to the change. Thus, the angular velocity ω of the motor 12 m causes the values of the parameters (β, L1, L2) of the disturbance observer unit 33 to change accordingly.
[0038] The disturbance observer unit 33 has a function of calculating the frequency of the disturbance T m based on the angular velocity ω of the motor 12. There is a correlation between the angular velocity ω ld of the motor 12 and the frequency of the disturbance T m . The disturbance observer unit 33 calculates the frequency of the disturbance T ld based on the phase relationship between the angular velocity ω m of the motor 12 and the frequency of the disturbance T ld . The disturbance observer unit 33 calculates the frequency of the disturbance T m corresponding to the angular velocity ω ld of the motor 12. For example, the disturbance observer unit 33 stores a map defining the relationship between the angular velocity ω m of the motor 12 and the frequency of the disturbance T ld . The disturbance observer unit 33 uses the map to calculate the frequency of the disturbance T m corresponding to the angular velocity ω ld of the motor 12.
[0039] The estimator 33A sets the values of the first observer gain L1 and the second observer gain L2 using the calculated frequency of the disturbance T ld . The estimator 33A estimates the differential value dT ld ^ of the disturbance T ld ^ using the first observer gain L1 and the second observer gain L2 having values corresponding to the calculated frequency of the disturbance T ld .
[0040] The multiplier 33B sets the value of the gain β using the calculated frequency of the disturbance T ld . The multiplier 33B uses the calculated frequency of the disturbance T ldThe estimated disturbance T, calculated by estimator 33A, has a gain β that has a value corresponding to the frequency. ld The derivative of ^, dT ld By multiplying by ^, the first correction value I c1 Perform the calculation.
[0041] Thus, the disturbance observer unit 33 detects the angular velocity ω of the motor 12. m The disturbance T changes in response to the change. ld The frequency of is calculated. In addition, the disturbance observer unit 33 calculates the disturbance T ld The values of the gain β, the first observer gain L1, and the second observer gain L2 are changed in accordance with the change in frequency. This allows for a wider frequency range of disturbances T. ld The effect can be compensated for. That is, as shown by the arrow X in the graph of Figure 3, the disturbance T can be removed. ld Center frequency f c Even if the center frequency f f changes, c Disturbance T having ld It can be removed precisely.
[0042] However, disturbance T ld When the parameter values of the disturbance observer unit 33 are changed in accordance with the change in the frequency of disturbance T, ld Other situations may arise that are different from the above. For example, the angular velocity ω of motor 12. m This is slower, and the angular velocity ω of motor 12 per unit time m This is a situation where the amount of change is larger. Under these circumstances, the disturbance T ld This is caused by changing the parameter values of the disturbance observer unit 33 in response to changes in the frequency of the disturbance T. ld There is a risk of torque fluctuations in motor 12 occurring other than those suppressing the above.
[0043] Therefore, disturbance T ld In order to suppress torque fluctuations of the motor 12 caused by changes in the parameter values of the disturbance observer unit 33 in response to changes in the frequency, the first observer gain L1 may be set as shown in equation (11) below.
[0044] L1=2·ω(t)·α-(dω(t) / dt) / ω(t) …(11) The second term on the right-hand side of equation (11), "(dω(t) / dt) / ω(t)", is a correction term for the first observer gain L1. The correction term is the disturbance T ld The setting is based on the perspective of suppressing torque fluctuations of the motor 12 caused by changes in the parameter values of the disturbance observer unit 33 in response to changes in the frequency of the disturbance T. ld When the frequency does not change, that is, the angular velocity ω of motor 12 m When is constant, the value of the correction term is "0". Disturbance T ld When the frequency changes, that is, the angular velocity ω of motor 12 m When this changes, the correction term becomes a value other than "0", thereby correcting the value of the first observer gain L1.
[0045] Thus, the disturbance observer unit 33 detects the angular velocity ω of the motor 12. m Disturbance T associated with changes ld The value of the first observer gain L1 is corrected according to the change in the frequency of the disturbance T. ld Disturbance T is caused by changing the parameter values of the disturbance observer unit 33 in response to changes in frequency. ld This allows for the suppression of torque fluctuations of motor 12 other than suppressing disturbance T. ld Even if the parameter values of the disturbance observer unit 33 are changed in accordance with the change in the frequency of disturbance T, ld The impact can be appropriately compensated for.
[0046] <Effects of the First Embodiment> The first embodiment provides the following effects: (1-1) The disturbance observer unit 33 uses the nominal plant Pn, which is a model that simulates plant P, to observe disturbance T ld We estimate the disturbance T ld Based on the current command value I *The disturbance observer unit 33 corrects the disturbance T having a specific frequency to be suppressed. ld It has parameters that are adjusted to suppress vibrations caused by a specific frequency T. ld Only the effect of can be compensated. The parameter is the compensated disturbance T. last The compensated disturbance T is adjusted to have a frequency response corresponding to the anti-resonance characteristics of plant P. last By inputting this into plant P, vibrations generated in plant P can be suppressed or canceled out.
[0047] (1-2) The disturbance observer unit 33 controls the current command value I * and the angular velocity ω of motor 12 m Based on this, disturbance T is applied to the mechanical device 13. ld This is estimated. Unlike when the rotation angle θ of motor 12 is used, there is no need to calculate the midpoint of motor 12. The midpoint of motor 12 is the rotation angle θ of motor 12 that corresponds to the reference operating state of the mechanical device 13. For this reason, the motor control device 11 does not need to have a function to calculate the midpoint of motor 12.
[0048] (1-3) The disturbance observer unit 33 estimates the disturbance T ld The derivative of ^, dT ld By multiplying ^ by the gain β, the current command value I is obtained. * The first correction value I for c1 The derivative value dT is calculated. ld Since we only need to multiply ^ by the gain β, the first correction value I c1 It can be easily calculated.
[0049] (1-4) Disturbance T ld Post-compensated disturbance T is added to Plant P after its effects have been compensated. last It has the transfer characteristics represented by the following equation (A). This is based on the previous equation (3). {Js 2 +(-L2·β+L1·J)s+L2} / {Js2 +(-L2·C+L1·J)s+L2}·Js …(A) When the value of the second term "(-L2·β+L1·J)s" in the numerator of equation (A) is "0", the disturbance T on plant P is ld The transmission ratio of T is theoretically "0". Therefore, the value of the gain β of the disturbance observer unit 33 is adjusted so that the value of the second term in the numerator of equation (A) is "0" or a value closer to "0". By adjusting the value of the gain β, the disturbance T can be controlled more appropriately. ld It can be suppressed.
[0050] (1-5) The disturbance observer unit 33 measures the angular velocity ω of the motor 12. m And consequently, external disturbance T ld The values of the gain β, the first observer gain L1, and the second observer gain L2 are changed in accordance with the change in frequency. This allows for a wider frequency range of disturbances T. ld The effect of can be compensated for. That is, the disturbance T can be removed. ld Center frequency f c Even if the center frequency f f changes, c Disturbance T having ld It can be removed precisely.
[0051] (1-6) The disturbance observer unit 33 measures the angular velocity ω of the motor 12. m When the value changes, the value of the first observer gain L1 is corrected in order to suppress torque fluctuations of the motor 12 caused by changes in the parameter value. The disturbance observer unit 33 adjusts the angular velocity ω of the motor 12. m Disturbance T associated with changes ld The value of the first observer gain L1 is corrected according to the change in the frequency of the disturbance T. ld Disturbance T is caused by changing the parameter values of the disturbance observer unit 33 in response to changes in frequency. ld This allows for the suppression of torque fluctuations of motor 12 other than suppressing disturbance T. ld Even if the parameter values of the disturbance observer unit 33 are changed in accordance with the change in the frequency of disturbance T, ldThe impact can be appropriately compensated for.
[0052] <Second Embodiment> A motor control device 11 according to a second embodiment will now be described. This embodiment basically has the same configuration as the first embodiment shown in Figures 1 to 3 above. Therefore, the same reference numerals are used for the same components and components as in the first embodiment, and their detailed descriptions are omitted.
[0053] The mechanical device 13 may be an electric power steering device. In this case, the motor 12 is an assist motor. The assist motor generates an assist torque that is applied to the steering mechanism of the vehicle. The assist torque is a torque that assists in steering the steering wheel. The steering mechanism includes a steering shaft connected to the steering wheel and a steering shaft that steers the steering wheels of the vehicle. The assist torque is applied to the steering shaft or the steering shaft. The command value calculation unit 31 calculates the steering torque T detected by the torque sensor. h The current command value I for the assist motor is determined accordingly. * The steering torque T is calculated. h This is the torque applied to the steering wheel. Steering torque T h S is a state variable that indicates the steering state of the steering device. sv That is the case.
[0054] The mechanical device 13 may be a steer-by-wire steering system. In this case, the motor 12 is a reaction motor or a steering motor. The reaction motor generates a steering reaction torque applied to the steering shaft of the vehicle. The steering reaction torque is a torque in the opposite direction to the steering direction of the steering wheel. The command value calculation unit 31 calculates the steering torque T detected by the torque sensor. h The current command value I for the reaction motor is determined accordingly. * The steering motor generates steering torque to steer the steering wheels of the vehicle. The command value calculation unit 31 calculates the current command value I for the steering motor according to the steering angle of the steering wheel. *The steering angle is calculated based on the rotation angle θ of the motor 12, for example, detected by the rotation angle sensor 12A. Steering torque T h And the steering angle is a state variable S that indicates the steering state of the steering device. sv That is the case.
[0055] If the motor 12 is an assist motor or a reaction motor, the motor control device 11 may be configured as follows. In other words, as shown by the dashed line in Figure 2, the motor control device 11 has a compensator 34 and a multiplier 35. The compensator 34 receives the steering torque T detected by the torque sensor. h The torque derivative is calculated by differentiating it, and the disturbance T is measured according to the calculated torque derivative. ld Compensation amount dT to compensate for the effect ca The multiplier 35 calculates the compensation amount dT. ca By multiplying by the gain β, the second correction value I is obtained. c2 The second correction value I is calculated. c2 This is the current value. Subtractor 33C is the second correction value I c2 Current command value I * This is added to the steering torque T. h The motor torque's responsiveness to changes is improved. As a result, a smoother steering feel is achieved. It also has the effect of suppressing disturbances such as reverse input vibrations from the steering wheels or brake vibrations generated during braking.
[0056] The compensator 34 is represented by the following equation (12). Equation (12) is a second-order differential equation. α2(t)·{(σ 2 / σt 2 )·x0(t)}+α1(t)·{(σ / σt)·x0(t)}+α0(t) 2 ·x0(t)=T d (t) …(12) However, "α2" is the first coefficient. The first coefficient is the coefficient of the second derivative term, which is the first term on the left side of equation (12). "α1" is the second coefficient. The second coefficient is the coefficient of the first derivative term, which is the second term on the left side of equation (12). "α0" is the third coefficient. "t" is time. "x0(t)" is the input to the compensator 34, and here it is the steering torque T h It is. "T d " is the output of compensator 34, and here the compensation amount dT ca That is the case.
[0057] Angular velocity ω of motor 12 m Disturbance T associated with changes ld To accommodate the change in frequency, the first coefficient α2, the second coefficient α1, and the third coefficient α0 are set as shown in equations (13) to (15).
[0058] α²(t) = 1 / ω(t) 2 …(13) α1(t) = 2·α / ω(t) …(14) α0(t)=1 …(15) However, "t" is time. "ω(t)" is the frequency at time t, which can change over time. "α" is the first parameter.
[0059] Angular velocity ω of motor 12 m Disturbance T due to changes ld When the value of the frequency ω(t) changes, the values of the first coefficient α2 and the second coefficient α1 change accordingly. As a result, the compensator 34 can detect disturbances T over a wider frequency range. ld The impact can be compensated for.
[0060] However, disturbance T ld The disturbance T is caused by changing the values of the first coefficient α2 and the second coefficient α1 in response to the change in frequency. ld There is a risk of torque fluctuations in motor 12 occurring other than those suppressing the above.
[0061] Therefore, disturbance T ldIn order to suppress torque fluctuations of the motor 12 caused by changes in the value of the first coefficient α2 and the second coefficient α1 in response to changes in the frequency, the second coefficient α1 may be set as shown in equation (16).
[0062] α1(t)=2·α / ω(t)-α2(t)·(dω(t) / dt) / ω(t) …(16) Here, "t" is time. "ω(t)" is the frequency at time t, which can change over time. "α" is the first parameter. "α2(t)" is the first coefficient of the compensator 34 at time t.
[0063] The second term on the right-hand side of equation (16), "α2(t)·(dω(t) / dt) / ω(t)", is the correction term for the second coefficient α1 of the compensator 34. The correction term is the disturbance T ld The setting is based on the perspective of suppressing torque fluctuations of the motor 12, which are caused by changes in the values of the first coefficient α2 and the second coefficient α1 of the compensator 34 in response to changes in the frequency of the disturbance T. ld When the frequency does not change, that is, the angular velocity ω of motor 12 m When is constant, the value of the correction term is "0". Disturbance T ld When the frequency changes, that is, the angular velocity ω of motor 12 m When this changes, the correction term becomes a value other than "0", thereby correcting the value of the second coefficient α1.
[0064] Thus, the compensator 34 measures the angular velocity ω of the motor 12. m Disturbance T associated with changes ld The value of the second coefficient α1 is corrected according to the change in frequency. This corrects the disturbance T ld The disturbance T is caused by changing the values of the coefficients (α1, α2) of the compensator 34 in response to the change in frequency. ld This allows for suppression of torque fluctuations in motor 12 other than those related to suppressing the motor itself.
[0065] <Effects of the second embodiment> The second embodiment provides the following effects in addition to the effects described in sections (1-1) to (1-6) of the first embodiment.
[0066] (2-1) The compensator 34 takes the value of the first coefficient α2, which is the coefficient of the second differential term of the second differential equation representing the compensator 34, and the value of the second coefficient α1, which is the coefficient of the first differential term, as the angular velocity ω of the motor 12. m , and consequently external disturbances T ld It is changed in accordance with the change in frequency. This allows for a wider frequency range of disturbances T ld The effect of can be compensated for. That is, the disturbance T can be removed. ld Center frequency f c Even if the center frequency f f changes, c Disturbance T having ld It can be removed precisely.
[0067] (2-2) The compensator 34 controls the angular velocity ω of the motor 12. m When the value of the first coefficient α2 and the value of the second coefficient α1 change, the value of the second coefficient α1 is corrected in order to suppress torque fluctuations of the motor 12 caused by changes in the values of the first coefficient α2 and the second coefficient α1. The compensator 34 adjusts the angular velocity ω of the motor 12. m Disturbance T associated with changes ld The value of the second coefficient α1 is corrected according to the change in frequency. This corrects the disturbance T ld The disturbance T is caused by changing the values of the coefficients (α1, α2) of the compensator 34 in response to the change in frequency. ld This allows for the suppression of torque fluctuations of motor 12 other than suppressing disturbance T. ld Even if the values of the coefficients (α1, α2) of the compensator 34 are changed in accordance with the change in the frequency of the disturbance T, ld The impact can be appropriately compensated for.
[0068] <Other Embodiments> This embodiment may be implemented with the following modifications. As shown by the dashed line in Figure 2, the disturbance observer unit 33 may have a disturbance feedback controller 33D and an adder 33E. The disturbance feedback controller 33D calculates the estimated disturbance T calculated by the estimator 33A. ld The derivative of ^, dT ld ^ is incorporated, and this incorporated estimated disturbance T ld The derivative of ^, dT ld Based on ^, the third correction value I c3 The third correction value I is calculated. c3 The estimated disturbance T is the difference between the actual motor output and the estimated motor output. ld This is the current value corresponding to ^. Adder 33E is a disturbance. ld The current command value I obtained after the effects of [the specified factor] have been compensated for. * The third correction value I c3 By adding this, the final current command value I * The feedback calculation unit 32 calculates the final current command value I * Based on this, feedback control of the current supplied to motor 12 is performed. In this way, the value of the current supplied to motor 12 is more quickly determined by the current command value I * To follow suit.
[0069] ·When the mechanical device 13 is a vehicle steering device and the motor 12 is an assist motor or a reaction motor, the disturbance observer unit 33 may be configured as follows. That is, when the situation is such that vibrations caused by torque ripple of the motor 12 are unlikely to appear in the steering device, the disturbance observer unit 33 is configured as follows. ld The disturbance compensation control, which compensates for the effects of the vibrations, may be stopped. For example, vibrations caused by torque ripple are easily transmitted to the steering device when the vehicle speed is very low. For this reason, the disturbance observer unit 33 may be configured to stop the disturbance compensation control when the vehicle speed exceeds the vehicle speed threshold. The speed threshold is the criterion for determining whether the vehicle speed is very low. Also, vibrations caused by torque ripple are transmitted to the angular velocity ω of the motor 12. m When the angular velocity ω is extremely low, it is easily transmitted to the steering device. For this reason, the disturbance observer unit 33 detects the angular velocity ω. mThe disturbance compensation control may be stopped when the value exceeds the angular velocity threshold. The angular velocity threshold is the angular velocity ω of the motor 12. m This is the criterion for determining whether it is extremely slow. The angular velocity ω of motor 12. m This reflects the steering speed of the steering wheel.
[0070] The motor control device 11 may have a function to detect its own abnormality, the motor 12's abnormality, or the mechanical device 13's abnormality. In this case, the disturbance observer unit 33 may stop the disturbance compensation control when an abnormality is detected in the motor control device 11, the motor 12, or the mechanical device 13. Performing compensation control when an abnormality is detected in the motor control device 11, the motor 12, or the mechanical device 13 is wasteful.
[0071] The command value calculation unit 31 may be configured as follows: That is, the command value calculation unit 31 uses a state variable S that indicates the state of the machine device 13. sv Based on this, the torque command value is calculated, and the current command value I is calculated based on this calculated torque command value. * The calculation may be performed in this manner. The torque command value is the torque that should be generated by the motor 12. In this case, the estimator 33A calculates the torque command value and the angular velocity ω of the motor 12, which is the output of plant P. m The estimator 33A takes in the torque command value and the angular velocity ω of the motor 12. m Estimated disturbance T based on ld The derivative of ^, dT ld The ^ operator is used. Multiplier 33B calculates the estimated disturbance T. ld The derivative of ^, dT ld The torque correction value is calculated by multiplying ^ by a predetermined gain. The torque correction value is a correction value for the torque command value. The subtractor 33C corrects the torque command value by subtracting the torque correction value from the torque command value. Even in this way, disturbances T having frequencies to be suppressed ld It is possible to compensate for the impact.
[0072] The disturbance observer unit 33 may be configured as follows: The disturbance observer unit 33 calculates the difference between the rotation angle θ of the motor 12 obtained as the output of plant P and the estimated rotation angle of the motor 12 obtained as the output of nominal plant Pn, and based on this calculated difference value, it detects disturbance T ld The effect of this may be compensated for. The rotation angle θ of motor 12 is the rotation information of motor 12.
[0073] The mechanical device 13 is not limited to a vehicle's steering system. The mechanical device 13 may be, for example, a machine tool driven by a motor.
Claims
1. A command value calculation unit configured to calculate command values for controlling the motor of a mechanical device, The system includes a disturbance observer unit configured to estimate disturbances applied to the mechanical device based on the command value and the motor's rotation information, and to correct the command value based on the estimated disturbances, The disturbance observer unit has parameters that are adjusted to compensate for the effects of disturbances having a specific frequency to be suppressed. The disturbance that is applied to the machine after the effects of the aforementioned disturbance have been compensated is the post-compensated disturbance. The parameters are adjusted so that the compensated disturbance has a frequency characteristic corresponding to the anti-resonance characteristics of the mechanical device. The disturbance observer unit is configured to change the value of the parameter in accordance with the rotation information of the motor. The rotational information of the motor is the angular velocity of the motor. The aforementioned parameters include gain, The aforementioned disturbance observer unit is, Based on the command value and the angular velocity of the motor, the derivative of the disturbance is calculated. A motor control device configured to calculate a first correction value for the command value by multiplying the calculated derivative value of the disturbance by the gain.
2. The parameter further includes a first observer gain and a second observer gain, When "J" is the coefficient of inertia of the machine, "C" is the viscosity coefficient of the machine, "s" is the Laplace operator, "L1" is the first observer gain, "L2" is the second observer gain, and "β" is the gain, The aforementioned compensated disturbance is given by the following equation (A): {JS ２ +(-L2・β+L1・J)s+L2} / {Js ２ It has a transfer characteristic represented by +(-L2・C+L1・J)s+L2}・Js …(A), The motor control device according to claim 1, wherein the disturbance observer unit is configured to correct the value of the first observer gain in order to suppress torque fluctuations of the motor caused by changes in the value of the parameter when the angular velocity of the motor changes.
3. The motor control device according to claim 2, wherein the value of the gain "β" is adjusted such that the value of the second term in the numerator of formula (A) is zero or a value close to zero.
4. The aforementioned mechanical device is configured to operate even when torque is applied from an external source. The motor control device further, A compensator configured to calculate a compensation amount for compensating for the effects of the disturbance in accordance with the derivative of the torque applied to the mechanical device from the outside, The device includes a multiplier that calculates a second correction value for the command value by multiplying the compensation amount by the gain, The motor control device according to any one of claims 1 to 3, wherein the compensator is configured to change the value of a first coefficient, which is the coefficient of the second differential term of the second differential equation representing the compensator, and the value of a second coefficient, which is the coefficient of the first differential term, according to the rotation information of the motor.
5. The motor control device according to claim 4, wherein the compensator is configured to correct the value of the second coefficient in order to suppress torque fluctuations of the motor caused by changes in the value of the first coefficient and the value of the second coefficient when the angular velocity of the motor changes.
6. The aforementioned disturbance observer unit is, Based on the command value and the angular velocity of the motor, the derivative of the disturbance is calculated. A motor control device according to any one of claims 1 to 5, configured to calculate a third correction value for the command value based on the calculated differential value of the disturbance.
7. The aforementioned mechanical device is a steering device for a vehicle, The motor control device according to any one of claims 1 to 6, wherein the motor generates torque applied to the steering device.