JP2014053993A - Motor controller and electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor controller which can update a motor resistance constant precisely, and to provide an electric power steering device having the motor controller.SOLUTION: In an electric power steering device, the d-axis command current is set based on a setting map for setting a larger d-axis command current as the rotation angular speed increases. An update switching set value ωα is set in a range of the rotation angular speed ω when the d-axis command current has a value smaller than a set value on the setting map, and in the range of high rpm range of the rotation angular speed ω of the motor. When the rotation angular speed ω of the motor is less than the update switching set value ωα, the motor resistance constant R is updated. When the rotation angular speed ω of the motor goes above the update switching set value ωα, a back electromotive voltage constant Ke is updated.

Description

  The present invention relates to a motor control device and an electric power steering device having the motor control device.

As a motor control device used for an electric power steering device, for example, the technology of Patent Literature 1 and the technology of Patent Literature 2 are known.
In the motor control devices described in Patent Document 1 and Patent Document 2, the motor is controlled by an inverter. A PWM (Pulse Width Modulation) signal is formed based on the d-axis command voltage Vdobj and the q-axis command voltage Vqobj. The d-axis command voltage Vdobj and the q-axis command voltage Vqobj are calculated by an equation including a d-axis command current idobj, a q-axis command current iqobj, a motor resistance constant R, and a constant Φ.

JP 2010-252484 A JP 2010-130707 A

  By the way, a technique using an equation including a d-axis command current idobj, a q-axis command current iqobj, a motor resistance constant R, and a counter electromotive voltage constant Ke is known instead of the above equation. A technique for updating the motor resistance constant R and the counter electromotive voltage constant Ke during driving of the motor is also known. According to this technique, the d-axis command voltage Vdobj and the q-axis command voltage Vqobj can be calculated more accurately than when the values of the motor resistance constant R and the counter electromotive voltage constant Ke are fixed values. However, the motor resistance constant R may not be updated accurately. At this time, each of the d-axis command voltage Vdoj and the q-axis command voltage Vqobj deviates from the target value. As a result, problems such as torque ripple are not solved, and the steering feeling of the electric power steering apparatus is reduced.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a motor control device capable of accurately updating a motor resistance constant in a motor control device that updates a motor resistance constant R and a counter electromotive voltage constant. An object is to provide an electric power steering apparatus having the apparatus and its motor control apparatus.

  (1) A motor control device according to claim 1 calculates a d-axis command voltage and a q-axis command voltage using a d-axis command current, a q-axis command current, a motor resistance constant, and a counter electromotive voltage constant, In the motor control device that controls the motor based on the d-axis command voltage and the q-axis command voltage, the d-axis command current sets the d-axis command current to a larger value as the rotational angular velocity of the motor increases. An update switching set value for switching between the update of the motor resistance constant and the update of the counter electromotive voltage constant is set based on a setting map, and the d-axis command current is set to a setting value in the setting map. The motor resistance constant when the rotational angular velocity of the motor is less than the update switching set value and is set within the range of the rotational angular velocity when the motor is at a small value and within the high rotational range of the motor. Updating the angular velocity of the motor when the higher the update switch setting value, and updates the counter electromotive voltage constant.

The motor resistance constant and the counter electromotive voltage constant have a mutually affecting relationship.
That is, the motor resistance constant changes depending on the magnitude of the back electromotive force constant. Further, the back electromotive voltage constant varies depending on the magnitude of the motor resistance constant. For this reason, it is not preferable to update the motor resistance constant and the counter electromotive voltage constant at the same time.

  Therefore, in the present technology, when the rotational angular velocity of the motor is less than the update switching set value, the motor resistance constant is updated. When the motor rotation angular velocity is greater than or equal to the update switching set value, the back electromotive force constant is updated. As a result, the motor resistance constant and the counter electromotive voltage constant can be accurately updated.

  Further, in the present technology, the update switching set value is set within the range of the rotational angular velocity when the d-axis command current is smaller than the set value and within the high rotational range of the rotational angular velocity of the motor. As a result, the motor resistance constant can be accurately updated.

  (2) The motor control device according to claim 2 calculates a d-axis command voltage and a q-axis command voltage using a d-axis command current, a q-axis command current, a motor resistance constant, and a counter electromotive voltage constant, In the motor control device that controls the motor based on the d-axis command voltage and the q-axis command voltage, the d-axis command current sets the d-axis command current to a larger value as the rotational angular velocity of the motor increases. A first update switching setting value for switching between updating of the motor resistance constant and updating of the counter electromotive voltage constant and a second value larger than the first update switching setting value are set based on a setting map. An update switching set value is set within the range of the rotational angular velocity when the d-axis command current is smaller than the set value in the setting map and within the high rotation range of the motor. When the rotation angular velocity is smaller than the first update switching setting value from a value larger than the first update switching setting value, the motor resistance constant is updated, and the rotation angular velocity of the motor is When the rotational angular velocity becomes larger than the second update switching setting value from a value smaller than the second updating switching setting value, the counter electromotive voltage constant is updated.

  When only one update switching setting value is set, when the rotational angular velocity of the motor changes back and forth across the update switching setting value, the update of the back electromotive force constant and the update of the motor resistance constant R are continuously performed. There is a risk of switching. In contrast, when the first update switching setting value and the second update switching setting value are set as described above, the update of the back electromotive force constant and the update of the motor resistance constant are continuously switched. Is suppressed.

  (3) The motor control device according to claim 3 is the motor control device according to claim 1 or 2, wherein the high rotational speed range of the motor is a rotational angular velocity at which the motor torque of the motor is smaller than a maximum rating. It has the structure of being a range. In this configuration, the update switching set value is set in a rotational angular velocity range in which the motor torque of the motor is smaller than the maximum rating in the motor torque characteristic graph.

  (4) The motor control device according to claim 4 is the motor control device according to any one of claims 1 to 3, wherein the rotational angular velocity of the motor is less than the update switching set value or a first update switching. When the condition that the q-axis command current is larger than the set current value is satisfied in addition to the condition that the motor resistance constant is less than the set value, the motor resistance constant is updated.

  In updating the motor resistance constant, the larger the value of the q-axis command current, the smaller the difference (that is, error) between the calculated motor resistance constant and the actual motor resistance constant. For this reason, according to this configuration, the motor resistance constant can be updated more accurately than when the q-axis command current is smaller than the set current value.

  (5) An electric power steering apparatus according to a fifth aspect includes the motor control apparatus according to any one of the first to fourth aspects. Since the motor control device can accurately calculate the d-axis command voltage and the q-axis command voltage, the steering feeling of the electric power steering device is improved. That is, according to this configuration, an electric power steering device with high steering feeling can be provided.

The schematic diagram which shows typically the electric power steering apparatus of embodiment. The figure explaining a dq axis coordinate system. The block diagram which shows the motor control apparatus of embodiment. The figure which shows an example of the setting map for setting d-axis command electric current. The flowchart of the PWM signal formation process which the motor control apparatus of embodiment performs. The flowchart of the constant update process which the motor control apparatus of embodiment performs. The figure which shows the switching setting range of an update switching setting value about the motor control apparatus of embodiment. FIG. 8A and FIG. 8B are diagrams showing temporal changes in rotational angular velocity, motor resistance constant, and counter electromotive voltage constant.

An electric power steering apparatus according to an embodiment will be described with reference to FIG.
The electric power steering device 1 includes a steering angle transmission mechanism 10 that transmits the rotation of the steering wheel 2 to the steered wheels 3, and a steering angle transmission mechanism that assists the operation of the steering wheel 2 (hereinafter referred to as "assist force"). 10 is provided with an EPS actuator 20 applied to the motor 10 and a motor control device 30 that controls the EPS actuator 20. The electric power steering apparatus 1 is provided with a plurality of sensors that detect the operating state of these apparatuses.

  The steering angle transmission mechanism 10 includes a steering shaft 11, a rack and pinion mechanism 12 that transmits the rotation of the steering shaft 11 to the rack shaft 13, a rack shaft 13 that operates the tie rod 14, and a tie rod 14 that operates the knuckle arm 15. Is provided.

  The EPS actuator 20 includes a motor 21 and a speed reduction mechanism 22 that decelerates the rotation of the motor 21. The rotation of the motor 21 is decelerated by the speed reduction mechanism 22 and transmitted to the steering shaft 11. At this time, the motor torque applied from the motor 21 to the steering shaft 11 acts as an assist force.

  The motor 21 is configured by a brushless motor. The motor 21 includes a rotor 21a (see FIG. 2) configured by permanent magnets and a stator 21b configured by three-phase windings (u phase, v layer, w phase). Further, a position sensor 33 (see FIG. 3) for detecting the position of the rotor 21a (hereinafter referred to as “rotor angle θ”) is attached to the motor 21. The position sensor 33 is configured by, for example, a resolver, a hall element, or an optical element.

The steering angle transmission mechanism 10 operates as follows.
When the steering wheel 2 is operated, an assist force is applied to the steering shaft 11 and the steering shaft 11 rotates. The rotational motion of the steering shaft 11 is converted into a linear motion of the rack shaft 13 by the rack and pinion mechanism 12. The rack shaft 13 moves the knuckle arm 15 via the tie rod 14 attached to the end of the rack shaft 13 to change the steering angle of the steered wheels 3.

A torque sensor 31 and a vehicle speed sensor 32 are attached to the electric power steering apparatus 1.
The torque sensor 31 outputs a signal (hereinafter referred to as “steering torque τ”) corresponding to the magnitude of torque applied to the steering shaft 11 by operation of the steering wheel 2. The vehicle speed sensor 32 outputs a signal corresponding to the rotational angular velocity of the steered wheels 3 (hereinafter referred to as “vehicle speed v”).

  The motor control device 30 sets the d-axis command current idobj and the q-axis command current iqobj based on the steering torque τ and the vehicle speed v. Further, the motor control device 30 forms the d-axis command voltage Vdojj and the q-axis command voltage Vqobj using the d-axis command current idobj and the q-axis command current iqobj, and coordinates the d-axis command voltage Vdojj and the q-axis command voltage Vqobj. Convert. Further, the motor control device 30 forms a PWM signal for controlling the motor 21 and controls the motor 21 based on the PWM signal.

FIG. 2 shows the relationship between the three-phase coordinate system of the motor 21 and the dq axis coordinate system.
The d-axis is an axis along the magnetic flux direction of the rotor 21a of the motor 21.
The q axis is an axis along the direction of the motor torque Tm generated by the motor 21.

  The q axis is orthogonal to the d axis. That is, the d axis and the q axis constitute an orthogonal coordinate system. The dq axis coordinate system rotates in synchronization with the rotor 21a. The rotor angle θ of the rotor 21a is defined as an angle with respect to the three-phase coordinates. For example, the rotor angle θ is an angle set with the u-phase direction as a reference axis, as shown in FIG.

The configuration of the motor control device 30 will be described below.
The motor control device 30 includes a first circuit group 40 that forms a PWM signal. The first circuit group 40 includes a target current setting circuit 41, a motor voltage formation circuit 42, a first coordinate conversion circuit 43, a PWM signal formation circuit 44, and a motor drive circuit 45.

  The motor control device 30 further includes a second circuit group 50 for updating the motor resistance constant R and the counter electromotive voltage constant Ke. The second circuit group 50 includes a second coordinate conversion circuit 51, an update circuit 52, and a storage unit 53 that stores a motor resistance constant R and a counter electromotive voltage constant Ke.

  The motor control device 30 further calculates an angle calculation circuit 61 that calculates the position of the rotor 21 a based on the output signal from the position sensor 33, and calculates the rotational angular velocity ω of the motor 21 based on the output from the angle calculation circuit 61. And a rotational angular velocity calculation circuit 62.

Each element of the motor control device 30 will be described.
The target current setting circuit 41 sets the d-axis command current idobj and the q-axis command current iqobj based on the steering torque τ and the vehicle speed v or the rotational angular velocity ω.

In setting the d-axis command current idobj, a setting map using the rotational angular velocity ω of the motor 21 as a parameter is used.
In setting the q-axis command current iqobj, a setting map using the steering torque τ and the vehicle speed v as parameters is used.

FIG. 4 shows an example of a setting map used for setting the d-axis command current idobj.
The setting map used for setting the d-axis command current idobj is a setting map for performing the flux-weakening control.

The d-axis command current idobj is set as follows.
The d-axis command current idobj is substantially “0” when the rotational angular velocity ω of the motor 21 is small. Where the rotational angular velocity ω of the motor 21 is in the vicinity of the first set value ω1, the d-axis command current idobj gradually increases as the rotational angular velocity ω of the motor 21 increases. Where the rotational angular velocity ω of the motor 21 is in the vicinity of the second set value ω2, the d-axis command current idobj increases steeply as the rotational angular velocity ω of the motor 21 increases. In a range where the rotational angular velocity ω of the motor 21 is larger than the third set value ω3, the d-axis command current idobj is gradually increased as the rotational angular velocity ω of the motor 21 increases.

  The motor voltage forming circuit 42 (see FIG. 3) uses the d-axis command current idobj and the q-axis command current iqobj to calculate the d-axis command voltage Vdobj and the q-axis based on the following formulas (1) and (2). The command voltage Vqobj is calculated.

“Vdobj” indicates a d-axis command voltage.
“Vqobj” indicates a q-axis command voltage.
“Idobj” indicates a d-axis command current.
“Iqobj” indicates a q-axis command current.
“Ld” indicates d-axis self-inductance.
“Lq” indicates q-axis self-inductance.
“R” indicates a motor resistance constant.
“Ke” represents a back electromotive force constant.
“Ω” indicates the rotational angular velocity of the motor 21.
“P” indicates a differential operator (d / dt).

The d-axis self inductance Ld and the q-axis self inductance Lq are constants.
As the motor resistance constant R, a value stored as the motor resistance constant R in the storage unit 53 is used.

As the back electromotive voltage constant Ke, a value stored in the storage unit 53 as the back electromotive voltage constant Ke is used.
As the rotation angular velocity ω of the motor 21, a value output from the rotation angular velocity calculation circuit 62 is used.

  The first coordinate conversion circuit 43 performs a coordinate conversion process of the d-axis command voltage Vdojj and the q-axis command voltage Vqobj calculated by the motor voltage forming circuit 42, and a voltage corresponding to the three phases of the motor 21, that is, the u-phase command voltage. Vu, v-phase command voltage Vv, and w-phase command voltage Vw are formed.

The PWM signal forming circuit 44 forms a PWM signal based on the u-phase command voltage Vu, the v-phase command voltage Vv, and the w-phase command voltage Vw.
The motor drive circuit 45 supplies power to the motor 21 based on the PWM signal. The motor drive circuit 45 is configured by an inverter circuit including a switching element such as a power MOSFET (Power-Metal-Oxide-Semiconductor Field-Effect Transistor) and an IGBT (Insulated Gate Bipolar Transistor).

The motor drive circuit 45 and the motor 21 are connected by three wires 21c, 21d, and 21e.
A u-phase current sensor 34 for detecting a current flowing in the u-phase winding (hereinafter referred to as “u-phase current iu”) is attached to the wiring 21c connected to the u-phase.

A v-phase current sensor 35 for detecting a current flowing in the v-phase winding (hereinafter referred to as “v-phase current iv”) is attached to the wiring 21d connected to the v-phase.
The second coordinate conversion circuit 51 calculates the w-phase current iw based on the u-phase current iu and the v-phase current iv. The second coordinate conversion circuit 51 performs coordinate conversion processing of the u-phase current iu, the v-phase current iv, and the w-phase current iw, and is referred to as a d-axis current of the motor 21 (hereinafter referred to as “d-axis measurement current id”). ) And a q-axis current (hereinafter referred to as “q-axis measurement current iq”).

  The update circuit 52 is a circuit for sequentially updating the motor resistance constant R and the counter electromotive voltage constant Ke stored in the storage unit 53 to values corresponding to the motor state. Specifically, the motor resistance constant R and the counter electromotive voltage constant Ke are updated as follows.

When the first condition is satisfied, the motor resistance constant R is updated based on the equation (3).
The first condition is that both (A) the rotational angular velocity ω of the motor 21 is less than the update switching set value ωα and (B) the q-axis command current iqobj is larger than the set current value iα ((A ) And (B)).

When the second condition is satisfied, the back electromotive force constant Ke is updated based on the equation (4).
The second condition is that (C) the rotational angular velocity ω of the motor 21 is equal to or higher than the update switching set value ωα.

“Vdobj” indicates a d-axis command voltage.
“Vqobj” indicates a q-axis command voltage.
“Id” indicates a d-axis measurement current.
“Iq” indicates the q-axis measurement current.
“Ld” indicates d-axis self-inductance.
“Lq” indicates q-axis self-inductance.
“R” indicates a motor resistance constant.
“Ke” represents a back electromotive force constant.
“Ω” indicates the rotational angular velocity of the motor 21.
“P” indicates a differential operator (d / dt).

  The storage unit 53 stores the motor resistance constant R and the counter electromotive voltage constant Ke calculated by the update circuit 52. The motor resistance constant R and the counter electromotive voltage constant Ke stored in the storage unit 53 are referred to by the motor voltage forming circuit 42 when calculating the d-axis command voltage Vdobj and the q-axis command voltage Vqobj.

Next, the operation of the motor control device 30 will be described.
FIG. 5 shows the procedure of the PWM signal forming process executed by the motor control device 30.
In the PWM signal forming process, a PWM signal is formed.

  In step S110, the motor control device 30 acquires the steering torque τ and the vehicle speed v. Here, “acquisition” indicates that the motor control device 30 temporarily stores the steering torque τ and the vehicle speed v input to the motor control device 30.

  In step S120, the q-axis command current iqobj is set by comparing the steering torque τ and the vehicle speed v with the setting map for the q-axis command current iqobj. Further, the d-axis command current idobj is set by checking the rotational angular velocity ω of the motor 21 against the setting map for the d-axis command current idobj.

  In step S130, the d-axis command voltage Vdobj and the q-axis command voltage Vqobj are calculated based on the above formulas (1) and (2) using the d-axis command current idobj and the q-axis command current iqobj. Here, values stored in the storage unit 53 are used as the motor resistance constant R and the counter electromotive voltage constant Ke.

  In step S140, coordinate conversion processing of the d-axis command voltage Vdojj and the q-axis command voltage Vqobj calculated in step 130 is performed to form the u-phase command voltage Vu, the v-phase command voltage Vv, and the w-phase command voltage Vw. .

  In step S150, a PWM signal is formed based on u-phase command voltage Vu, v-phase command voltage Vv, and w-phase command voltage Vw calculated in step S140. The PWM signal is output to the motor drive circuit 45.

FIG. 6 shows a procedure of constant update processing executed by the motor control device 30.
In the constant update process, the motor resistance constant R and the counter electromotive voltage constant Ke are updated.
In step S210, the motor control device 30 acquires the rotational angular velocity ω of the motor 21. Here, “acquisition” indicates that the motor control device 30 temporarily stores the rotational angular velocity ω input to the motor control device 30.

  In step S220, it is determined whether or not the rotational angular velocity ω of the motor 21 is less than the update switching setting value ωα. When the determination in step S220 is affirmative, that is, when the rotational angular velocity ω of the motor 21 is less than the update switching setting value ωα, the process proceeds to step S230. In step S230, it is determined whether or not the q-axis command current iqobj is larger than the set current value iα. Here, when the q-axis command current iqobj is larger than the set current value iα, the motor resistance constant R is calculated, and the value of the motor resistance constant R stored in the storage unit 53 is changed to a newly calculated value. (In other words, calculation and update of the motor resistance constant R). On the other hand, when the determination in step S230 is negative, that is, when the q-axis command current iqobj is equal to or less than the set current value iα, the motor resistance constant R is not updated.

  When the determination is negative in step S220, that is, when the rotational angular velocity ω of the motor 21 is equal to or higher than the update switching set value ωα, the process proceeds to step S250. In step S250, the counter electromotive voltage constant Ke is calculated, and the value of the counter electromotive voltage constant Ke stored in the storage unit 53 is updated to the newly calculated value (that is, the counter electromotive voltage constant Ke is calculated and updated). ).

As described above, the motor resistance constant R and the counter electromotive voltage constant Ke of the motor 21 are updated. The reason for this update is as follows.
The magnitude of the motor resistance constant R varies depending on the ambient temperature of the motor 21 and the like. For this reason, the motor resistance constant R of the actual motor 21 may deviate from the value stored in the storage unit 53. For this reason, in order to make the motor resistance constant R memorize | stored in the memory | storage part 53 into the value close | similar to the actual motor resistance constant R, the value of the motor resistance constant R is updated.

  When the q-axis command current iqobj of the motor 21 is large, the calculation error in the above equation (3) becomes small. It is also done when big.

  The magnitude of the back electromotive voltage constant Ke varies depending on the magnitude of the rotational angular velocity ω of the motor 21. Therefore, the d-axis command voltage Vdobj and the q-axis command voltage Vqobj are calculated by the above equations (1) and (2), assuming that the back electromotive voltage constant Ke is a fixed value regardless of the rotational angular velocity ω of the motor 21. In this case, the calculation accuracy of the d-axis command voltage Vdobj and the q-axis command voltage Vqobj may be reduced. In order to suppress a decrease in the calculation accuracy of the d-axis command voltage Vdobj and the q-axis command voltage Vqobj, when the d-axis command voltage Vdoj and the q-axis command voltage Vqobj are calculated, the rotation angular velocity ω of the motor 21 at the time of the calculation is handled. It is preferable to use the counter electromotive voltage constant Ke.

  Further, the counter electromotive voltage constant Ke is substantially constant when the rotational angular velocity ω of the motor 21 is small, but varies greatly when the rotational angular velocity ω of the motor 21 is large. That is, when the rotational angular velocity ω of the motor 21 is large, there is a possibility that a large divergence occurs between the value of the counter electromotive voltage constant Ke stored in the storage unit 53 and the value of the actual counter electromotive voltage constant Ke. For this reason, it is preferable to periodically update the counter electromotive voltage constant Ke when the rotational angular velocity ω of the motor 21 is large. For this reason, the counter electromotive voltage constant Ke is updated when the rotational angular velocity ω is a large value.

  By the way, as shown in the above equations (3) and (4), the equation indicating the motor resistance constant R includes the back electromotive force constant Ke. The equation indicating the back electromotive force constant Ke includes a motor resistance constant R. For this reason, the motor resistance constant R and the counter electromotive voltage constant Ke interfere with each other, and when one becomes unstable, the other becomes unstable. Therefore, as shown in the constant update process, the motor resistance constant R and the counter electromotive voltage constant Ke are not updated at the same time. That is, with the rotational angular speed ω of the motor 21 as a parameter, the update switching set value ωα is used as a boundary, and only the motor resistance constant R is updated in the range below the update switching set value ωα, and the back electromotive force is raised in the range above the update switching set value ωα. Only the voltage constant Ke is updated.

That is, the update switching set value ωα is a value for setting a boundary between the update of the motor resistance constant R and the update of the counter electromotive voltage constant Ke.
The update switching setting value ωα is set within a predetermined setting range (hereinafter referred to as “switching setting range RA”) at the rotational angular velocity ω of the motor 21.

An example of the switching setting range RA will be described with reference to FIG.
The update switching setting value ωα is set within a switching setting range RA that satisfies the following conditions.
The upper limit of the switching setting range RA is set to the rotational angular velocity ωβ when the d-axis command current idobj is at the set value β in the setting map for setting the d-axis command current idobj.

The set value β is set as follows.
The condition is that the counter electromotive voltage constant Ke calculated when the d-axis command current idobj is “0” and the counter electromotive voltage constant Ke calculated when the d-axis command current idobj is set to the set value X are the same value within the error range. The range of the set value X is obtained. The upper limit value of the set value X range is set to the set value β. This indicates that the update switching setting value ωα is set within the range of the rotational angular velocity ω (d-axis small current range) in which the d-axis command current idobj is set to a small value.

  The lower limit value of the switching setting range RA of the update switching setting value ωα is the vicinity where the motor torque Tm starts to decrease with an increase in the rotational angular velocity ω in the torque characteristic graph showing the relationship between the motor torque Tm and the rotational angular velocity ω of the motor 21. (Hereinafter, this value is referred to as “rotational angular velocity ωγ”). This indicates that the update switching set value ωα is set in the high rotation range of the motor 21.

  That is, the switching setting range RA of the update switching setting value ωα is a range of the rotational angular velocity ω (d-axis small current range) in which the d-axis command current idobj is set to a small value, and the rotational angular velocity ω of the motor 21 is high. The area (high rotation area) is set.

The reason why the switching setting range RA of the update switching setting value ωα is limited as described above will be described with reference to FIG.
FIG. 8 shows that the manner in which the motor resistance constant R is updated and the manner in which the back electromotive force constant Ke is updated differ depending on how the update switching set value ωα is set.

  FIG. 8A shows how the updated values of the motor resistance constant R and the counter electromotive voltage constant Ke change when the update switching set value ωα is set to exceed the upper limit of the switching setting range RA. FIG. 8B shows how the motor resistance constant R and the counter electromotive voltage constant Ke are changed when the update switching set value ωα is set within the switching setting range RA.

Common items in FIG. 8A and FIG. 8B are as follows.
From time t0 to time t1, the rotational angular velocity ω of the motor 21 is greater than the update switching setting value ωα. In this time zone, since the rotational angular velocity ω of the motor 21 is larger than the update switching setting value ωα, the counter electromotive voltage constant Ke is periodically updated. On the other hand, the motor resistance constant R is not updated. For this reason, in the time zone from time t0 to time t1, the value of the motor resistance constant R is a constant value.

  When the time exceeds the time t1, the rotation angular speed ω of the motor 21 is smaller than the update switching setting value ωα, and the updated constant is switched. That is, the motor resistance constant R is periodically updated. On the other hand, the counter electromotive voltage constant Ke is not updated.

  By the way, as shown in FIG. 8A, when the update switching setting value ωα is set to exceed the upper limit of the switching setting range RA, the d-axis command current idobj is larger than a value near “0”. , The value of the counter electromotive voltage constant Ke stored in the storage unit 53 by the update process is used as the counter electromotive voltage constant Ke for calculating the update of the motor resistance constant R.

  On the other hand, as shown in FIG. 8B, when the update switching setting value ωα is set within the switching setting range RA, the update processing is performed when the d-axis command current idobj is a value near “0”. The value of the counter electromotive voltage constant Ke stored in the storage unit 53 is used as the counter electromotive voltage constant Ke for calculating the update of the motor resistance constant R.

The difference depending on whether or not the update switching setting value ωα is set within the switching setting range RA results in the following difference in operation.
According to the equation (3), in order to accurately calculate the motor resistance constant R, it is preferable to calculate the motor resistance constant R when the d-axis command current idobj can be regarded as “0”. Therefore, in order to accurately calculate the motor resistance constant R based on the above equation (3), the back electromotive force constant Ke when the d-axis command current idobj is “0” or near “0” is used. Is preferred. However, as shown in FIG. 8A, when the update switching setting value ωα is set to exceed the upper limit of the switching setting range RA, the d-axis command current idobj is set to a value larger than a value near “0”. At some point, the constants to be updated are switched. For this reason, the back electromotive force constant Ke that has been updated and stored in the storage unit 53 when the d-axis command current idobj is larger than a value near “0” is used to update the motor resistance constant R thereafter. Is used as the value of the back electromotive force constant Ke. For this reason, when the update switching setting value ωα is set to exceed the upper limit of the switching setting range RA, the motor resistance constant R obtained by updating may deviate from the actual motor resistance constant R. .

  On the other hand, when the update switching setting value ωα is set within the switching setting range RA as shown in FIG. 8B, the update target is set when the d-axis command current idobj is in the vicinity of “0”. The constant of is switched. For this reason, when the d-axis command current idobj is in the vicinity of “0”, the back electromotive voltage constant Ke that is updated and stored in the storage unit 53 is the back electromotive voltage constant for updating the motor resistance constant R thereafter. Used as the value of Ke. For this reason, when the update switching setting value ωα is set within the switching setting range RA, the motor resistance constant R obtained by updating is prevented from deviating from the actual motor resistance constant R. That is, the motor resistance constant R is accurately updated.

  For the reasons described above, when the update switching setting value ωα is set within the switching setting range RA, compared to the case where the update switching setting value ωα is set to exceed the upper limit of the switching setting range RA, The motor resistance constant R is accurately updated.

The reason why the lower limit value of the switching setting range RA of the update switching setting value ωα is set as described above is as follows.
Although it is possible to set the lower limit value of the switching setting range RA of the update switching setting value ωα to a value smaller than the lower limit of the switching setting range RA shown above, the switching setting range RA of the updating switching setting value ωα If the lower limit value is made too small, the opportunity to update the motor resistance constant R decreases. For this reason, the lower limit value of the switching setting range RA of the update switching setting value ωα is as shown in the above in the characteristic graph of the motor torque Tm and the rotational angular velocity ω of the motor 21 with respect to the increase of the rotational angular velocity ω of the motor 21 Thus, it is set to a value (rotational angular velocity ωγ) in the vicinity where the motor torque Tm starts to decrease.

According to the present embodiment, the following effects can be achieved.
(1) In the present embodiment, in the setting map for the d-axis command current iobjj, within the range of the rotational angular velocity ω when the d-axis command current iobjj is smaller than the set value β and within the high rotation range of the motor 21. In addition, an update switching set value ωα is set. When the rotational angular velocity ω of the motor 21 is less than the update switching set value ωα, the motor resistance constant R is updated. When the rotational angular velocity ω of the motor 21 is equal to or higher than the update switching set value ωα, the counter electromotive voltage constant Ke is updated.

  In the present technology, the update of the motor resistance constant R and the update of the counter electromotive voltage constant Ke are performed based on whether or not the rotational angular velocity ω of the motor 21 is smaller than the update switching set value ωα. Thereby, the motor resistance constant R and the counter electromotive voltage constant Ke can be accurately updated.

  Further, according to the present technology, the update switching setting value ωα is set within the range of the rotational angular velocity ω and the high rotation range of the motor 21 when the d-axis command current idobj is a small value in the setting map of the d-axis command current idobj. Set. Thereby, the motor resistance constant R is accurately updated.

  (2) In the present embodiment, the high rotation range of the rotation angular velocity ω of the motor 21 is a rotation angular velocity range in which the motor torque Tm of the motor 21 is smaller than the maximum rating in the torque characteristic graph of the motor 21. In the case of this configuration, the update switching set value ωα is set in a rotational angular velocity range in which the motor torque Tm of the motor 21 is smaller than the maximum rating.

  (3) In the present embodiment, as the update condition of the motor resistance constant R, in addition to the condition that the rotational angular velocity ω of the motor 21 is less than the update switching set value ωα, the q-axis command current iqobj is greater than the set current value iα. Add the condition that it is large.

  According to the update process of the motor resistance constant R, the difference (that is, the error) between the calculated motor resistance constant R and the actual motor resistance constant R becomes smaller as the value of the q-axis command current iqobj is larger. Therefore, the motor resistance constant R can be updated more accurately than when the q-axis command current iqobj is smaller than the set current value iα.

  (4) The electric power steering device 1 of the present embodiment includes the motor control device 30 having the above configuration. Since the motor control device 30 accurately calculates the d-axis command voltage Vdobj and the q-axis command voltage Vqobj, the steering feeling of the electric power steering device 1 is improved. That is, according to this configuration, it is possible to provide the electric power steering apparatus 1 having a high steering feeling.

(Modification)
The embodiment according to the present technology is not limited to the embodiment exemplified in the above embodiment. For example, the present invention can be modified as shown below. Further, the following modified examples are not applied only to the above embodiment.

  In the above embodiment, only one update switching setting value ωα is set in the switching setting range RA. However, two update switching setting values ωα are set in the switching setting range RA as follows (hereinafter referred to as the first update switching setting). The value ωα1 and the second update switching setting value ωα2) can also be set.

  The second update switching setting value ωα2 is set to a value larger than the first update switching setting value ωα1. The first update switching setting value ωα1 is a setting value for switching between the update of the back electromotive force constant Ke and the motor resistance constant R in the process in which the rotational angular velocity ω of the motor 21 decreases. The second update switching setting value ωα2 is a setting value for switching between updating the back electromotive force constant Ke and updating the motor resistance constant R in the process of increasing the rotational angular velocity ω of the motor 21.

This has the following effects.
When only one update switching setting value ωα is set in the switching setting range RA, when the rotational angular velocity ω of the motor 21 changes back and forth across the update switching setting value ωα, the update of the back electromotive force constant Ke and the motor There is a possibility that a situation in which the update of the resistance constant R is continuously switched (hereinafter referred to as “switching chattering phenomenon”) may occur. On the other hand, when the first update switching setting value ωα1 and the second update switching setting value ωα2 are set in the switching setting range RA as described above, the occurrence of the switching chattering phenomenon is suppressed.

  In the above embodiment, the present technology is applied to a three-phase brushless motor, but the application of the present technology is not limited to this type of motor. That is, the present technology can be applied to the motor 21 having a structure that can be controlled by the d-axis command current idobj and the q-axis command current iqobj.

  In the above embodiment, the present technology is applied to the column-type electric power steering device 1, but the present technology can also be applied to the pinion type and rack assist type electric power steering device 1. Also in this case, the effect according to the effect of the embodiment can be obtained by adopting the configuration according to the embodiment.

  DESCRIPTION OF SYMBOLS 1 ... Electric power steering device, 2 ... Steering wheel, 3 ... Steering wheel, 10 ... Steering angle transmission mechanism, 11 ... Steering shaft, 12 ... Rack and pinion mechanism, 13 ... Rack shaft, 14 ... Tie rod, 15 ... Knuckle arm, DESCRIPTION OF SYMBOLS 20 ... EPS actuator, 21 ... Motor, 21a ... Rotor, 21b ... Stator, 21c, 21d, 21e ... Wiring, 22 ... Deceleration mechanism, 30 ... Motor controller, 31 ... Torque sensor, 32 ... Vehicle speed sensor, 33 ... Position sensor 34 ... u-phase current sensor, 35 ... v-phase current sensor, 40 ... first circuit group, 41 ... target current setting circuit, 42 ... motor voltage forming circuit, 43 ... first coordinate conversion circuit, 44 ... PWM signal forming circuit 45 ... Motor drive circuit, 50 ... second circuit group, 51 ... second coordinate conversion circuit, 52 ... update circuit, 53 ... storage unit, 6 ... angle calculation circuit, 62 ... rotational angular velocity calculating circuit.

Claims (5)

A d-axis command voltage and a q-axis command voltage are calculated using a d-axis command current, a q-axis command current, a motor resistance constant, and a counter electromotive voltage constant, and the motor is based on the d-axis command voltage and the q-axis command voltage. In a motor control device for controlling
The d-axis command current is set based on a setting map for setting the d-axis command current to a large value as the rotational angular velocity of the motor increases.
The range of the rotational angular velocity when the update switch setting value for switching between the update of the motor resistance constant and the update of the counter electromotive voltage constant is a value smaller than the set value in the setting map. Within the high rotation range of the motor,
When the rotational angular velocity of the motor is less than the update switching set value, the motor resistance constant is updated,
The motor control device, wherein the counter electromotive voltage constant is updated when the rotational angular velocity of the motor is equal to or greater than the update switching set value. A d-axis command voltage and a q-axis command voltage are calculated using a d-axis command current, a q-axis command current, a motor resistance constant, and a counter electromotive voltage constant, and the motor is based on the d-axis command voltage and the q-axis command voltage. In a motor control device for controlling
The d-axis command current is set based on a setting map for setting the d-axis command current to a large value as the rotational angular velocity of the motor increases.
A first update switching setting value for switching between updating of the motor resistance constant and updating of the counter electromotive voltage constant and a second update switching setting value larger than the first update switching setting value are the d in the setting map. Is set within the range of the rotational angular velocity when the axis command current is smaller than the set value and within the high rotation range of the motor,
When the rotational angular velocity of the motor becomes a value smaller than the first update switching setting value from a value larger than the first update switching setting value, the motor resistance constant is updated,
The counter electromotive voltage constant is updated when the rotational angular velocity of the motor changes from a value smaller than the second update switching setting value to a value larger than the second update switching setting value. Motor control device. The motor control device according to claim 1 or 2,
The motor control device characterized in that the high rotation range of the motor is a rotation angular velocity range in which the motor torque of the motor is smaller than a maximum rating. In the motor control device according to any one of claims 1 to 3,
When the condition that the q-axis command current is larger than the set current value is satisfied in addition to the condition that the rotational angular velocity of the motor is less than the update switch setting value or less than the first update switch setting value, the motor resistance constant The motor control apparatus characterized by updating.   An electric power steering device having the motor control device according to any one of claims 1 to 4.