Motor control device, electric actuator, and electric power steering device

Abstract

To provide a motor controller, an electric actuator, and an electric power steering device that can accurately avoid the duty saturation of a motor.SOLUTION: A motor controller comprises: a voltage command value calculation unit for calculating a voltage command value for the voltage applied to a motor based on a current command value; a duty calculation unit for calculating the duty of the voltage command value to an available supply voltage, based on the voltage command value calculated by the voltage command value calculation unit and the available supply voltage to a drive circuit of the motor; and a voltage command value suppression unit for suppressing the voltage command value calculated by the voltage command value calculation unit based on the duty calculated by the duty calculation unit.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] BACKGROUND ART Conventionally, permanent magnet type synchronous motors (brushless DC motors) have been widely used as drive sources for electric power steering devices, for example. In this type of motor vector control, if the duty (= control voltage / available supply voltage) exceeds 100%, the control voltage will be limited by the available supply voltage (VR voltage), causing the three-phase control voltage to have a nonlinear waveform, resulting in problems such as abnormal motor noise and vibration. Therefore, as a technique for suppressing abnormal motor noise due to duty saturation, for example, the technique described in Patent Document 1 is known. This technique calculates the current value at which the duty becomes 100% from the motor voltage equation, and limits this in the dimension of the current command value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6662504 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology described in Patent Document 1 limits the maximum duty usage rate by limiting the current command value, but there is a problem in that the limit value of the current command value contains errors due to dynamic changes in the motor state, environmental changes such as temperature, and manufacturing variations, which deteriorates the accuracy of limiting the maximum duty usage rate. There are three main reasons for this: (1) Although the motor voltage equation is a differential equation, the differential term is ignored. In other words, the current value is solved as an algebraic equation, so dynamic characteristics are ignored. (2) To remove noise, the power supply voltage (VR voltage) and the motor rotation angular velocity used as input signals are processed through a low-pass filter (LPF), which causes a phase delay. (3) Since the motor constants used as design constants are subject to temperature changes and manufacturing variations, it is difficult to match the design values ​​with the actual values.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a motor control device, an electric actuator, and an electric power steering device that can accurately avoid duty saturation of a motor. [Means for solving the problem]

[0006] In order to solve the above problem, one aspect of the present invention provides a motor control device that drives and controls a motor, and includes: a voltage command value calculation unit that calculates a voltage command value of a voltage to be applied to the motor based on a current command value; a duty calculation unit that calculates a duty of the voltage command value with respect to a voltage that can be supplied to a drive circuit of the motor based on the voltage command value calculated by the voltage command value calculation unit and the voltage that can be supplied to the drive circuit of the motor; and a voltage command value suppression unit that suppresses the voltage command value calculated by the voltage command value calculation unit based on the duty calculated by the duty calculation unit.

[0007] Furthermore, in the above motor control device, when the duty calculated by the duty calculation unit exceeds 100%, the voltage command value suppression unit may suppress the voltage command value so that the duty becomes 100%.

[0008] Furthermore, in the above motor control device, the voltage command value suppression unit may include a suppression gain calculation unit that calculates a suppression gain of the voltage command value based on the duty calculated by the duty calculation unit, and a multiplication unit that multiplies the suppression gain calculated by the suppression gain calculation unit by the voltage command value.

[0009] In the motor control device, the suppression gain calculation section may calculate, as the suppression gain, an inverse number of the duty calculated by the duty calculation section. Furthermore, in the above motor control device, the suppression gain calculation unit may include a q-axis suppression gain calculation unit that calculates the suppression gain for the q-axis, and a d-axis suppression gain calculation unit that calculates the suppression gain for the d-axis, and the d-axis suppression gain calculation unit may output the suppression gain for the d-axis with a delay of one sample period.

[0010] Moreover, the motor control device may further include a filter processing unit that performs low-pass filtering on the voltage command value calculated by the voltage command value calculation unit, and the multiplication unit may multiply the suppression gain by the low-pass filtering. Furthermore, in the above motor control device, the voltage command value calculation unit may include at least an integrator, and the above motor control device may further include a second multiplication unit that multiplies the integrator by the suppression gain calculated by the suppression gain calculation unit.

[0011] Furthermore, one aspect of the motor control method of the present invention is a motor control method for driving and controlling a motor, comprising the steps of: calculating a voltage command value for a voltage to be applied to the motor based on a current command value; calculating a duty of the voltage command value with respect to a voltage that can be supplied to a drive circuit of the motor based on the voltage command value and the voltage that can be supplied to the drive circuit of the motor; and suppressing the voltage command value based on the duty.

[0012] An electric actuator according to one aspect of the present invention includes any one of the motor control devices described above and the motor that is driven and controlled by the motor control device. Furthermore, an electric power steering device according to one aspect of the present invention includes any of the motor control devices described above and the motor that is driven and controlled by the motor control device, and applies a steering assist force to the steering system of the vehicle by the motor. [Effects of the Invention]

[0013] According to one aspect of the present invention, the current duty is calculated and fed back to suppress the voltage command value (control voltage), thereby making it possible to accurately avoid motor duty saturation without being affected by dynamic changes in the motor's state, environmental changes such as temperature, or manufacturing variations. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a configuration example showing an outline of an electric power steering device. [Figure 2] FIG. 2 is a block diagram illustrating an example of the functional configuration of the control unit. [Figure 3] FIG. 3 is a control block diagram of the current control unit in the first embodiment. [Figure 4] FIG. 4 shows an example of multiplication of the control voltage suppression gain in the PID controller. [Figure 5] FIG. 5 shows an example of multiplication of the control voltage suppression gain in the EMF disturbance suppressor. [Figure 6] FIG. 6 is an explanatory diagram of the dq-axis control voltages Vd_0 and Vq_0. [Figure 7] FIG. 7 is an explanatory diagram of a method for suppressing the q-axis control voltage. [Figure 8] FIG. 8 is an explanatory diagram of a method for suppressing the d-axis control voltage. [Figure 9] FIG. 9 shows an example of the dq-axis control voltages and duties before and after suppression. [Figure 10] FIG. 10 is a control block diagram of the current control unit in the second embodiment. [Figure 11] FIG. 11 is a diagram showing the conditions under which the simulation was performed. [Figure 12] FIG. 12 is an enlarged view of the three-phase control voltages. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The scope of the present invention is not limited to the following embodiments, and can be arbitrarily modified within the scope of the technical concept of the present invention.

[0016] (First embodiment) A first embodiment of the present invention will be described below. FIG. 1 is a diagram showing an example of the configuration of an electric power steering device 100 equipped with a motor control device according to this embodiment. A column shaft 2 of a steering handle (steering wheel) 1 is connected to a tie rod 6 of a steered wheel (not shown) via a reduction gear 3, universal joints 4A and 4B, and a pinion rack mechanism 5. A torque sensor 10 that detects the steering torque of the steering handle 1 is provided on the column shaft 2. A motor 20 that assists the steering force of the steering handle 1 is also connected to the column shaft 2 via the reduction gear 3.

[0017] The control unit (ECU) 30 operates by receiving power from a battery 14, which is an on-board power source. The negative terminal of the battery 14 is grounded, and the positive terminal thereof is connected to the ECU 30 via an ignition switch 11 that starts the engine, and is also connected directly to the ECU 30 without going through the ignition switch 11. The ECU 30 may be, for example, a computer including a processor and peripheral components such as a storage device, etc. The processor may be, for example, a CPU (Central Processing Unit) or an MPU (Micro-Processing Unit). The storage device may include any of a semiconductor storage device, a magnetic storage device, and an optical storage device. The storage device may include a register, a cache memory, a memory such as a ROM (Read Only Memory) used as a main memory, and a RAM (Random Access Memory). The ECU 30 realizes the function of a motor control device by the processor executing a predetermined program. The motor 20 and the ECU 30 together constitute an electric actuator.

[0018] The ECU 30 may be configured by dedicated hardware for executing each of the information processes described below. For example, the ECU 30 may include a functional logic circuit configured in a general-purpose semiconductor integrated circuit, or may include a programmable logic device (PLD) such as a field-programmable gate array (FPGA).

[0019] The ECU 30 receives as input the steering torque Th detected by the torque sensor 10 and the vehicle speed Vh detected by the vehicle speed sensor 12. Then, the ECU 30 calculates a steering assist command value of the assist command using an assist map or the like based on the steering torque Th and the vehicle speed Vh, and controls the drive current supplied to the motor 20 based on the calculated steering assist command value. Here, the motor 20 is a permanent magnet synchronous motor. The motor 20 can be, for example, a three-phase brushless motor. The reduction gear 3 can be, for example, a worm gear. In this case, the torque generated by the motor 20 is transmitted to a worm wheel via a worm inside the reduction gear 3, causing the worm wheel to rotate. As a result, the reduction gear 3 increases the torque generated by the motor 20 and applies an auxiliary steering torque to the column shaft 2.

[0020] An example of the functional configuration of the control unit (ECU) 30 will be described with reference to FIG. As shown in FIG. 2, the ECU 30 includes a basic current command value calculation unit 31a, a current command value calculation unit 31b, subtractors 32a and 32b, a current control unit 33, a two-phase / three-phase conversion unit 34, a PWM control unit 35, an inverter (INV) 36, a three-phase / two-phase conversion unit 37, and an angular velocity conversion unit 38.

[0021] The basic current command value calculation unit 31a calculates a current command value Iref to be applied to the motor 20 based on the steering torque Th and the vehicle speed Vh. The current command value calculation unit 31b calculates the current command value Iref and the VR voltage V R (voltage that can be supplied from the battery 14 to the inverter 36) and the rotational angular velocity ω of the motor 20 E Based on this, the q-axis current command value I to be applied to the motor 20 is calculated. q * and the d-axis current command value I d * Calculate the following. Here, the current command value calculation unit 31b calculates the maximum value of the three-phase motor current when the maximum value of the system current I max The dq-axis current command value I is limited so that an overcurrent exceeding d * , I q * Calculate the following.

[0022] 3-phase motor current I a , I b and I c are detected by the current sensors 22a, 22b, and 22c, respectively. The detected three-phase motor currents I a , I b and I c is converted into the dq-axis current I by the three-phase / two-phase conversion unit 37. d , I q is converted to The subtractors 32a and 32b subtract the fed back current I q , I d is the q-axis current command value I q * and the d-axis current command value I d * By subtracting from each, the q-axis deviation current ΔI q and d-axis deviation current ΔI d Calculate the q-axis deviation current ΔI q and d-axis deviation current ΔI d is input to the current control unit 33.

[0023] The current control unit 33 controls the q-axis deviation current ΔI q and d-axis deviation current ΔI d The control voltage (voltage command value) V q , V dThe two-phase / three-phase converter 34 calculates the dq-axis control voltage V d , V q The three-phase control voltage V a , V b and V c Convert to. The PWM control unit 35 controls the three-phase control voltage V a , V b and V c A PWM-controlled gate signal is generated based on the

[0024] The inverter 36 is a drive circuit for the motor 20. The inverter 36 is driven by a gate signal generated by the PWM control unit 35, and the q-axis deviation current ΔI q and d-axis deviation current ΔI d A current is supplied so that Further, a resolver (or a motor rotation angle sensor) 21 detects a motor angle (rotation angle) θ of the motor 20. An angular velocity conversion unit 38 converts the rotation angular velocity ω of the motor 20 based on the change in the motor angle θ. E The motor angle θ and rotational angular velocity ω are calculated. E is used for motor vector control.

[0025] In motor vector control, if the maximum duty (= control voltage / supplyable voltage) usage rate does not reach 100%, the following two problems will occur. [1] If it is less than 100%, the motor and ECU capabilities will not be fully utilized. [2] If it exceeds 100%, the control voltage will be limited by the supplyable voltage (VR voltage), causing the three-phase control voltage to have a nonlinear waveform, resulting in problems with motor operating noise and vibration.

[0026] Therefore, in this embodiment, in order to make the maximum duty usage rate 100%, the current duty is calculated in real time, and this is fed back to constantly correct the control voltage. Specifically, the current control unit 33 calculates the current duty, and if the calculated duty exceeds 100%, the dq-axis control voltage V d, V q Correct (suppress)

[0027] The design concept will be explained below. The following four methods are available to achieve a maximum duty utilization rate of 100% and suppress overcurrent. [Method 1: Duty calculation] dq axis control voltage V d ,V q [V] and VR voltage V R Based on [V], the current duty usage rate Duty[-] is calculated using the following formula. Duty=√(V d 2 +V q 2 ) / (A·V R ) ………(1) Here, the coefficient A above is A=1 / √3 when third harmonic compensation is performed, and A=1 / 2 when third harmonic compensation is not performed. Third harmonic compensation is a process that makes duty saturation less likely to occur by superimposing the third harmonic on the voltage applied to the motor to flatten the peak of the applied voltage waveform.

[0028] [Method 2: dq axis control voltage suppression] First, the control voltage suppression gain G is calculated based on the duty calculated in the means 1. Here, when the duty is 100% or more, the reciprocal of the duty is calculated as the control voltage suppression gain G as shown in the following equation. G=1 / Duty ………(2) On the other hand, when the duty is less than 100%, the control voltage suppression gain G=1.

[0029] Then, this control voltage suppression gain G is used to directly control the dq axis control voltage V d ,V q Suppress. Specifically, the control voltage suppression gain G is calculated by dividing the dq-axis control voltage V d ,V qBy multiplying by , the dq axis control voltage is suppressed. This makes it possible to make the duty 100% when the duty is 100% or more. Also, the dq axis control voltage V d ,V q As a countermeasure for winding up of the integrator in the PID controller that calculates the voltage, the integrator is also multiplied by the control voltage suppression gain G.

[0030] [Method 3: Calculation of d-axis current command value] The motor voltage equation and the circular condition for the dq-axis voltages are expressed by the following two formulas.

[0031]

number

[0032] Here, the above equations (3) and (4) are simultaneously set to obtain (V d ,V q Eliminating (and solving for the d-axis current) gives the following equation:

[0033]

number

[0034] The above equation (5) is the d-axis current command value Iref in the 100% duty region. d0 The calculation formula is as follows. Next, the system maximum current I max and q-axis current I q and the limit value Iref of the d-axis current command value. dLim is calculated as follows: Iref dLim =√(I max 2 -I q 2 ) ………(6)

[0035] And the limit value Iref of the d-axis current command value dLim and the d-axis current command value Iref d0The smaller one is used as the d-axis current command value Iref d Let's say. At this time, Iref d0 >Iref dLim If so, the d-axis current command value Iref d The reason why LPF processing is necessary is that when the combined value of the d-axis current and the q-axis current exceeds the circular condition, oscillation occurs. In order to mitigate this oscillation, Iref d0 >Iref dLim Only in this case, LPF processing is performed.

[0036] [Means 4: q-axis current command value limit] The q-axis current command value is limited taking into account the circular condition of the dq-axis current. First, the d-axis current command value Iref derived in the means 3 d and the system maximum current I max and the limit value Iref of the q-axis current command value. qLim Calculate. Iref qLim =√(I max 2 -Iref d 2 ) ………(7) And the limit value Iref of the q-axis current command value qLim and the current command value Iref, and the smaller one is used as the q-axis current command value Iref q Let's say. By limiting the dq-axis current command value as described above, the maximum value of the three-phase motor current is the system maximum current I max can be prevented from exceeding.

[0037] 3 is a control block diagram for realizing the above means 1 to 4. This Fig. 3 shows a control block diagram of the current command value calculation unit 31b, subtractors 32a and 32b, and current control unit 33 in Fig. 2.

[0038] The d-axis current command value calculation unit 41 realizes the above-mentioned means 3. As shown in FIG. 3, the d-axis current command value calculation unit 41 calculates the rotational angular velocity ω E [radE / s], VR voltage V R[V] and q-axis current I q Enter [A] and set the d-axis current command value Iref d The d-axis current command value calculation unit 41 calculates the calculated d-axis current command value Iref d is output to the q-axis current command value limiting unit 42 and the control band setting unit 44. The q-axis current command value limiting unit 42 realizes the above-mentioned means 4. As shown in FIG. 3, the q-axis current command value limiting unit 42 limits the current command value Iref [A] and the d-axis current command value Iref d Enter [A] and set the q-axis current command value Iref q The q-axis current command value limiting unit 42 calculates the calculated q-axis current command value Iref q to the control band setting unit 43. The control band setting units 43 and 44 set the control bands, respectively, and the dq-axis current command value Iref d , Iref q The dq-axis current command value I d * , I q * Output.

[0039] The q-axis deviation current ΔIq calculated by the subtractor 32a is input to a current controller (PID controller) 46, which outputs a q-axis control voltage. The PID controller 46 includes an integrator 46a, a comparator 46b, and a differentiator 46c. As shown in FIG. 4, the integrator 46a also includes a multiplier 46d that multiplies the q-axis deviation current ΔIq by a control voltage suppression gain G output from a control voltage suppressor 60 (described later). The output of the PID controller 46 is input to an EMF disturbance suppressor 47.

[0040] When the motor 20 rotates, a back electromotive force (EMF) is generated, and if this acts as a disturbance and enters the current control feedback loop, the PID controller 46 will no longer be able to flow the actual current according to the current command value, which is its original role, and the current deviation will increase. Therefore, the EMF disturbance suppressor 47 suppresses the EMF to reduce the current deviation.

[0041] The EMF disturbance suppressor 47 is a disturbance suppression unit that suppresses EMF disturbances using the simplest feedback method and reduces current deviation. As shown in Fig. 3, for example, the EMF disturbance suppressor 47 includes a delay device 47a and a low-pass filter (LPF) 47b, and performs LPF processing on the output of the PID controller 46 without any external input, and feeds back the LPF output with a delay to the output of the PID controller 46. The EMF disturbance suppressor 47 can approximately set the sensitivity function of voltage noise to "0" while suppressing current detection noise. As shown in FIG. 5, the LPF 47b includes a multiplier 47c that multiplies the LPF 47b by a control voltage suppression gain G output from a control voltage suppressor 60, which will be described later.

[0042] The output of the EMF disturbance suppressor 47 is input to an LR converter 48. The LR converter 48 is a characteristic conversion unit that converts the motor electrical characteristic LR into the desired motor electrical characteristic L0R0 to stabilize the control system. The LR converter 48 can be configured with a first- or second-order filter. The q-axis control voltage V output from the LR converter 48 q is input to the control voltage suppressor 60. The current controller (PID controller) 50, EMF disturbance suppressor 51, and LR converter 52 on the d-axis side have the same configuration as the current controller (PID controller) 46, EMF disturbance suppressor 47, and LR converter 48 on the q-axis side, and therefore will not be described here.

[0043] The control voltage suppressor 60 includes a duty calculation unit 61 and a suppression gain calculation unit 62 . The duty calculation unit 61 realizes the above-mentioned means 1. As shown in FIG. 3, the duty calculation unit 61 calculates the dq-axis control voltage V d ,V q [V] and VR voltage V R Input [V] and calculate the current duty (Duty) [-].

[0044] The suppression gain calculation unit 62 realizes the above-mentioned means 2. The suppression gain calculation unit 62 receives the duty calculated by the duty calculation unit 61, and outputs a control voltage suppression gain G[-] to the LPFs 47a and 51a in the EMF disturbance suppressors 47 and 51 and the integrators 46a and 50a in the PID controllers 46 and 50, as shown in FIG. In other words, by applying the control voltage suppression gain G to the LPF processing in the EMF disturbance suppressors 47 and 51, the dq-axis control voltage V d ,V q In addition, as a countermeasure against windup, the integrators 46a and 50a in the PID controllers 46 and 50 are also multiplied by the control voltage suppression gain G.

[0045] 3, the PID controllers 46 and 50 correspond to the voltage command value calculation unit, the duty calculation unit 61 corresponds to the duty calculation unit, the suppression gain calculation unit 62 corresponds to the suppression gain calculation unit, the multiplier 47c corresponds to the multiplication unit, and the suppression gain calculation unit 62 and the multiplication unit 47c correspond to the voltage command value suppression unit. Also, the LRF 47b corresponds to the filter processing unit, the integrators 46a and 50a correspond to the integrators, and the multiplier 46d corresponds to the second multiplication unit.

[0046] As described above, the motor control device in this embodiment controls the dq-axis control voltage V d , V q and the VR voltage V R Based on this, the duty of the control voltage relative to the available supply voltage is calculated, and the dq axis control voltage V d , V q Suppress. In this way, the motor control device of this embodiment calculates the current duty and feeds back the calculated current duty to constantly correct the control voltage. By using a feedback structure for the control voltage as described above, it is possible to reduce the influence of changes in the motor state, environmental changes such as temperature, and manufacturing variations, and to accurately adjust the dq-axis control voltage V d , V qThis allows the maximum duty usage rate to be accurately limited, preventing the duty from exceeding 100%. As a result, the occurrence of abnormal motor noise and vibration can be appropriately suppressed.

[0047] Furthermore, when the current duty is 100% or more, the motor control device of this embodiment adjusts the dq-axis control voltage V so that the duty becomes 100%. d , V q Specifically, the reciprocal (1 / Duty) of the calculated current duty (Duty) is calculated as the control voltage suppression gain G, and the calculated control voltage suppression gain G is used to suppress the dq-axis control voltage V d , V q can be multiplied by In this way, the maximum duty utilization rate can be set to 100%, so that the capabilities of the motor 20 and the ECU 30 can be utilized to the fullest extent.

[0048] In addition, the motor control device in this embodiment controls the dq-axis control voltage V d , V q When suppressing the dq-axis control voltage V, the control voltage suppression gain G is multiplied by the LPF processing in the EMF disturbance suppressors 47 and 51. d , V q can be suppressed. Furthermore, the motor control device in this embodiment multiplies the control voltage suppression gain G by the integrators 46a, 50a in the PID controllers 46, 50, so that the windup of the integrators 46a, 50a can be appropriately suppressed, thereby achieving stabilization of the system.

[0049] As described above, the motor control device in this embodiment suppresses the voltage command value (control voltage) using a feedback structure that is less susceptible to the effects of dynamic state changes in the motor, environmental changes such as temperature, and manufacturing variations, and therefore can accurately avoid motor duty saturation.

[0050] (Second embodiment) Next, a second embodiment of the present invention will be described. In the first embodiment described above, the d-axis control voltage V d and q-axis control voltage V q In this embodiment, the control voltage suppression gain G that maximizes the tracking ability in the 100% duty region is not common to the d-axis side and the q-axis side, but has different weights, and therefore the dq-axis control voltage V d ,V q An example of suppressing this will be described.

[0051] Hereinafter, a method for maximizing the rolling tracking performance in the 100% duty region will be described with reference to FIGS. [Means 1] Prepare a dq axis controller for the control voltage suppressor and calculate the current d axis control voltage V d_0 and q-axis control voltage V q_0 Here, the dq-axis controller may include a PID controller, an EMF disturbance suppressor, and an LR converter. The PID controller may have a configuration similar to that of the PID controllers 46 and 50 in FIG. 3, the EMF disturbance suppressor may have a configuration similar to that of the EMF disturbance suppressors 47 and 51 in FIG. 3, and the LR converter may have a configuration similar to that of the LR converters 48 and 52 in FIG. 3.

[0052] Figure 6 shows the d-axis control voltage V calculated by the dq-axis controller. d_0 and q-axis control voltage V q_0 dq-axis control voltage V d_0 , V q_0 The composite values ​​are indicated by white circles in the figure. In FIG. 6, the dotted circle indicates the area where the duty is 100%, and on the circumference, √(V d 2 +V q 2 )=A·V R This becomes:

[0053] [Means 2] The dq-axis control voltage V calculated in the method 1d_0 , V q_0 Using this, the control voltage suppression gain G for the q axis q Calculate the control voltage suppression gain G q is calculated so that the composite value of the dq-axis control voltages is on the circumference of a 100% duty, as shown by the arrow in FIG. 7(a). And this control voltage suppression gain G q As shown by the arrow α in Fig. 7(a), first, the q-axis control voltage V q_0 The q-axis control voltage after suppression is V shown by the dotted arrow in Figure 7(a). q_1 As a result, the combined value of the dq-axis control voltage is V d_0 ,V q_1 This results in a composite value that approaches the 100% duty circle (shown by the dotted line).

[0054] If the duty is 100% or less, the q-axis current I q is the q-axis current command value Iref q Therefore, the q-axis current I q is the q-axis current command value Iref shown by the dashed line in Fig. 7(b). q is limited by. This q-axis current I q By using the [Means 3: Calculation of d-axis current command value] process of the design concept explained in the first embodiment, the d-axis current command value Iref d Calculate.

[0055] [Means 3] The suppressed q-axis control voltage V calculated in the above means 2 q_1 and the d-axis control voltage before suppression V d_0 and are used to calculate the control voltage suppression gain G for the d axis. d Calculate the control voltage suppression gain G d is calculated so that the composite value of the dq-axis control voltages is on the circumference of a 100% duty, as shown by the arrow in FIG. 8(a).

[0056] And this control voltage suppression gain G d As shown by the arrow β in Fig. 8(a), the d-axis control voltage V d_0The d-axis control voltage after suppression is V shown by the dotted arrow in Figure 8(a). d_1 As a result, the combined value of the dq axis control voltage is V d_1 ,V q_1 This results in a composite value that approaches the 100% duty circle (the circle indicated by the dotted line). In this way, the d-axis control voltage V d_0 Suppress. If the duty is 100% or less, the d-axis current I d is the d-axis current command value Iref d Therefore, the d-axis current I d is the d-axis current command value Iref shown by the dashed line in Fig. 8(b). d is limited by.

[0057] By repeating the above steps 1 to 3, the composite value of the dq-axis control voltages can be brought closer to the circumference of the 100% duty, and ultimately the duty can be made 100%. In addition, when the duty is 100% or less, the dq-axis current I d ,I q is the dq axis current command value Iref d ,Iref q can be made to follow. Therefore, the above makes it possible to obtain the necessary transfer rate in the 100% duty region (black dots in FIG. 8(b)).

[0058] Next, the behavior of the dq-axis control voltage and duty cycle due to this function will be analyzed. The dq-axis control voltage before suppression is V d_0 ,V q_0 Then, Duty0 can be expressed by the following equation. Duty0=√(V d_0 2 +V q_0 2 ) / (A·V R )………(8) Then, the dq-axis control voltage V after suppression d_1 ,V q_1 can be expressed by the following equation:

[0059]

number

[0060] In other words, the weight w that suppresses the dq axis control voltage q , w d is expressed as follows:

[0061]

number

[0062] In addition, the dq-axis control voltage V d_1 ,V q_1 Duty1 can be calculated from the following formula:

[0063]

number

[0064] For example, as shown in Fig. 9(a), the d-axis control voltage V d_0 is 12[V], the q-axis control voltage before suppression V q_0 is 8[V], and the VR voltage A·V R When the voltage is 10[V], Duty0 is 1.44. After that, by suppressing the dq-axis control voltage using this function, the duty will transition as shown in Figure 9(b) as Duty1 = 1.06, Figure 9(c) as Duty2 = 1.01, and finally as shown in Figure 9(d) as Duty3 = 1.00, i.e., a duty of 100%.

[0065] 10 is a control block diagram for realizing the above means 1 to 3. In this Fig. 10, a control block diagram of the current control unit 33 in Fig. 2 is shown. In Fig. 10, the dq-axis controller 70A realizes means 1, the q-axis controller 70B realizes means 2, and the d-axis controller 70C realizes means 3. In Fig. 10, parts having the same configuration as in Fig. 3 are given the same reference numerals as in Fig. 3, and descriptions thereof will be omitted here.

[0066] The dq-axis controller 70A includes a PID controller 71, an EMF disturbance suppressor 72, and an LR converter 73. The PID controller 71 may have a configuration similar to that of the PID controllers 46 and 50, the EMF disturbance suppressor 72 may have a configuration similar to that of the EMF disturbance suppressors 47 and 51, and the LR converter 73 may have a configuration similar to that of the LR converters 48 and 52.

[0067] The q-axis controller 70B has the same configuration as the q-axis controller shown in Fig. 3. However, the duty calculation unit 61 calculates the dq-axis control voltage V d_0 , V q_0 3 in that it uses the following as an input. The d-axis controller 70C has a configuration in which a control voltage suppression unit 80 is added to the configuration on the d-axis side shown in Fig. 3. The control voltage suppression unit 80 includes a duty calculation unit 81, a suppression gain calculation unit 82, and a delay unit 83. The duty calculation unit 81 calculates the duty using the same calculation method as the duty calculation unit 61 provided in the q-axis controller 70B. The suppression gain calculation unit 82 calculates the control voltage suppression gain G d Calculate. The delay unit 83 delays the control voltage suppression gain G calculated by the suppression gain calculation unit 82. d The control voltage suppression gain G d_1 Output as

[0068] In FIG. 10, the suppression gain calculation unit 62 corresponds to the q-axis suppression gain calculation unit, and the suppression gain calculation unit 82 and delay unit 83 correspond to the d-axis suppression gain calculation unit.

[0069] The processing procedure in the control block diagram shown in FIG. 10 is as follows. (Step 1) The dq-axis controller 70A for the control voltage suppressor controls the dq-axis control voltage V d_0 ,V q_0 Calculate. (Step 2) The duty calculation unit 61 of the q-axis controller 70B calculates the dq-axis control voltage V d_0 ,V q_0 and VR voltage V R Based on this, the duty utilization rate Duty_q is calculated.

[0070] (Step 3) When the Duty_q calculated by the Duty calculation unit 61 is 100% or more, the suppression gain calculation unit 62 calculates the control voltage suppression gain G for the q axis, which is 1 / Duty. q Calculate. On the other hand, if the Duty_q calculated by the Duty calculation unit 61 is less than 100%, the suppression gain calculation unit 62 calculates the q-axis control voltage suppression gain G q is set to "1". (Step 4) The control voltage suppression gain G calculated in step 3 q is multiplied by the LPF 47b in the EMF disturbance suppressor 47 of the q-axis controller 70B and the integrator 46a in the PID controller 46. As a result, the q-axis control voltage V q_0 is suppressed, and the suppressed q-axis control voltage V q_1 Let's say.

[0071] (Step 5) The duty calculation unit 81 of the d-axis controller 70C calculates the q-axis control voltage V q_1 and the d-axis control voltage V output from the LR converter 52 of the d-axis controller 70C. d_0 and VR voltage V R Based on this, the duty utilization rate Duty_d is calculated. (Step 6) When the Duty_d calculated by the Duty calculation unit 81 is 100% or more, the suppression gain calculation unit 82 calculates the control voltage suppression gain G for the d axis, which is 1 / Duty. d Calculate. On the other hand, if the duty factor calculated by the duty factor calculation unit 81 is less than 100%, the suppression gain calculation unit 82 calculates the control voltage suppression gain G d is set to "1".

[0072] (Step 7) The delay circuit 82 delays the control voltage suppression gain G d is held for only one sample, and the control voltage suppression gain G d_1 Output as (Step 8) The control voltage suppression gain G calculated in step 7 d_1 is multiplied by the LPF 51b in the EMF disturbance suppressor 51 of the d-axis controller 70C and the integrator 50a in the PID controller 50. As a result, the d-axis control voltage V d_0 is suppressed, and the d-axis control voltage V d_1 Let's say. As a result, the dq-axis control voltages are suppressed so that the duty usage rate does not exceed 100%. Thereafter, steps 1 to 8 are repeated.

[0073] 11 and 12 are graphs showing the results of simulation verification performed to confirm the effects of this embodiment. The horizontal axis of each graph shown in Fig. 11 and Fig. 12 indicates time [s]. In the simulation verification, as shown by the two-dot chain line in Fig. 11(b), the maximum system current I max A current command value Iref fixed at (45A) was used, and an external torque was linearly applied to the motor shaft while the motor was rotating at high speed with no load. The simulation verification was terminated when the motor torque and external torque were balanced and the motor came to a standstill. In this simulation verification, the maximum d-axis current was set to 40[A] and the supply voltage (VR voltage) to 13.6[V].

[0074] In this case, the d-axis current command value calculation unit 41 calculates the d-axis current command value Iref with an upper limit of 40 [A] as shown by the dashed line in FIG. 11(a). d is calculated, and the q-axis current command value limiting unit 42 calculates the d-axis current command value Iref d and the current command value Iref, the q-axis current command value Iref is calculated as shown by the dashed line in FIG. 11(b). q Then, the current control unit 33 calculates the dq-axis current command value Iref d , Irefq At this time, the current control unit 33 calculates the dq-axis control voltages so that the duty usage rate becomes 100%. As a result, the d-axis current I d [A], the q-axis current I shown by the solid line in Fig. 11(b) q [A] is generated. Also, the rotation speed [rpm] shown in Figure 11(c) is generated. The q-axis current I in Fig. 11(b) q 11(c) and the time series waveform of the rotation speed in FIG. 11(d), it is clear that the NT characteristics are such that the rotation speed changes from high to low as the load changes from low to high. In this characteristic, the supply voltage (VR voltage) and three-phase control voltage were checked to confirm that the motor was producing maximum output.

[0075] Specifically, the supply voltage (VR voltage) and three-phase control voltage were checked in the following three regions. [1] Low load / high rotation speed range (5A, around 9400rpm) t1=0.4sec [2] Medium load / medium rotation speed range (23A, around 4000rpm) t2 = 0.87sec [3] High load / low rotation speed range (44A, around 1800rpm) t3=1.34sec

[0076] The results are shown in Figures 12(a) to 12(c), where Figure 12(a) shows the supply voltage (VR voltage) and three-phase control voltage in the low load / high rotation speed region, Figure 12(b) shows the medium load / medium rotation speed region, and Figure 12(c) shows the high load / low rotation speed region. In Figures 12(a) to 12(c), the thick solid lines indicate the VR voltage V R The thin solid line indicates the A-phase control voltage, the dotted line indicates the B-phase control voltage, and the dashed line indicates the C-phase control voltage. As is clear from Figures 12(a) to 12(c), the maximum value of the three-phase control voltage overlaps with the supply voltage (VR voltage), meaning that the duty cycle is 100%, confirming that the operation is as intended.

[0077] In this way, the motor control device in this embodiment calculates the control voltage suppression gain for the q axis and the control voltage suppression gain for the d axis, and outputs the control voltage suppression gain for the d axis with a delay of one sample period. d , V q The weights that suppress the can be changed as shown in the above equations (12) and (13). This allows for maximum tracking performance in the 100% duty region.

[0078] (Variation) In the above embodiments, the motor control device is described as being equipped with the EMF disturbance suppressors 47, 51, but the motor control device does not have to be equipped with the EMF disturbance suppressors 47, 51. In this case, the output of the PID controllers 46, 50 may be directly multiplied by the control voltage suppression gain. When the duty is 100% or more, the dq-axis control voltage V d , V q is only required to be suppressed, and the method of multiplying the control voltage suppression gain is not particularly limited.

[0079] Furthermore, in the above-described embodiments, an electric power steering device 100 that applies a steering assist force to a vehicle steering system using a motor is shown as an application example of the motor control device, but the present invention is not limited to the above. The motor control device in each of the above-described embodiments can be applied to various electric actuator products that drive and control permanent magnet synchronous motors (brushless DC motors). For example, the motor control device in each of the above-described embodiments can also be applied to actuators for preventing railway vibrations, etc.

[0080] The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. In this case, the program itself read from the storage medium realizes the functions of the embodiments. Furthermore, the storage medium on which the program is recorded can constitute the present invention. In addition, not only can the functions of the embodiments be realized by the computer executing the program it has read, but the operating system (OS) running on the computer may also perform some or all of the actual processing based on the instructions of the program, and the functions of the above-mentioned embodiments may be realized through that processing. [Explanation of symbols]

[0081] 100... electric power steering device, 41... d-axis current command value calculation unit, 42... q-axis current command value limiting unit, 43... control band setting unit, 44... control band setting unit, 46... PID controller, 46a... integrator, 46b... comparator, 46c... differentiator, 47... EMF disturbance suppressor, 47a... delay unit, 47b... low-pass filter (LPF), 48... LR converter, 50... PID controller, 50a... integrator, 50b...comparator, 50c...differentiator, 51...EMF disturbance suppressor, 51a...delay device, 51b...low-pass filter (LPF), 52...LR converter, 60...control voltage suppression unit, 61...duty calculation unit, 62...suppression gain calculation unit, 70A...dq-axis controller, 70B...q-axis controller, 70C...d-axis controller, 80...control voltage suppression unit, 81...duty calculation unit, 82...suppression gain calculation unit, 83...delay device

Claims

1. A motor control device that drives and controls a motor, a voltage command value calculation unit that calculates a voltage command value for the motor based on a current command value; a duty calculation unit that calculates a duty of the voltage command value with respect to a voltage that can be supplied to a drive circuit of the motor, based on the voltage command value calculated by the voltage command value calculation unit and the voltage that can be supplied to the drive circuit of the motor; a voltage command value suppression unit that suppresses the voltage command value calculated by the voltage command value calculation unit based on the duty calculated by the duty calculation unit, The voltage command value suppression unit a suppression gain calculation unit that calculates a suppression gain of the voltage command value based on the duty calculated by the duty calculation unit; a multiplication unit that multiplies the suppression gain calculated by the suppression gain calculation unit by the voltage command value.

2. The voltage command value suppression unit 2. The motor control device according to claim 1, wherein, when the duty calculated by the duty calculation unit exceeds 100%, the voltage command value is suppressed so that the duty becomes 100%.

3. The motor control device according to claim 1 , wherein the suppression gain calculation unit calculates the reciprocal of the duty calculated by the duty calculation unit as the suppression gain.

4. The suppression gain calculation unit a q-axis suppression gain calculation unit that calculates the suppression gain for the q-axis; a d-axis suppression gain calculation unit that calculates the suppression gain for the d-axis, The motor control device according to claim 1 , wherein the d-axis suppression gain calculation unit outputs the d-axis suppression gain with a delay of one sample period.

5. a filter processing unit that performs low-pass filtering on the voltage command value calculated by the voltage command value calculation unit, The motor control device according to claim 1 , wherein the multiplier multiplies the suppression gain by the low-pass filter processing.

6. the voltage command value calculation unit includes at least an integrator, The motor control device according to claim 1 , further comprising a second multiplier that multiplies the integrator by the suppression gain calculated by the suppression gain calculator.

7. A motor control method for driving and controlling a motor, comprising: calculating a voltage command value for the motor based on a current command value; calculating a duty of the voltage command value with respect to a voltage that can be supplied to a drive circuit of the motor based on the voltage command value and the voltage that can be supplied to the drive circuit of the motor; suppressing the voltage command value based on the duty, The step of suppressing the voltage command value includes: calculating a suppression gain of the voltage command value based on the duty; multiplying the suppression gain by the voltage command value.

8. The motor control device according to any one of claims 1 to 6, the motor that is driven and controlled by the motor control device; An electric actuator comprising:

9. The motor control device according to any one of claims 1 to 6, the motor that is driven and controlled by the motor control device, An electric power steering device that applies a steering assist force to the steering system of the vehicle by the motor.

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