Motor control device

Abstract

To derive an error of an actual value of a rotational angle of a rotator and a detection value without requiring a rotation of the rotator to both of a positive rotational direction and an inverse rotational direction.SOLUTION: A control device 10 is functioned as a command voltage derivation part 23 that introduces a d-shaft voltage command value Vd* and a q-shaft voltage command value Vq* when a rotator 101 is rotated by a power supplied to a motor 100 by a vector control, a three-phase / two-phase conversion part 27 that introduces a d-shaft current Id and a q-shaft current Iq when the rotator 101 is rotated, and an error derivation part 33 that derives a shaft-phase deviation Δθ as a rotational angle difference, which is an error of an actual value of a rotational angle of the rotator 101 and a rotational angle detection value θ, on the basis of rotational angle related information obtained by the rotational angle detection value θ, the respective voltage command values Vd* and Vq*, and the respective currents Id and Iq.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a motor control device that controls a brushless motor. [Background technology]

[0002] Patent Document 1 discloses a method for estimating a magnetic pole position error, which is a difference between a magnetic pole position indicated by an encoder provided in a permanent magnet motor and an actual value of the magnetic pole position. In this method, a first d-axis current, which is a d-axis current, a first q-axis current, which is a q-axis current, and a first d-axis voltage, which is a d-axis voltage, are derived by rotating a rotor of a permanent magnet motor in a forward direction. Then, a second d-axis current, which is a d-axis current, a second q-axis current, which is a q-axis current, and a second d-axis voltage, which is a d-axis voltage, are derived by rotating the rotor in a reverse direction. Then, a magnetic pole position error is derived based on the first d-axis current, the first q-axis current, and the first d-axis current derived when the rotor is rotated in the forward direction and the second d-axis current, the second q-axis current, and the second d-axis current derived when the rotor is rotated in the reverse direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-95023 A Summary of the Invention [Problem to be solved by the invention]

[0004] When deriving a magnetic pole position error by the method disclosed in Patent Document 1, it is necessary to rotate the rotor in both the forward direction and the reverse direction. [Means for solving the problem]

[0005] The motor control device for solving the above problem is a motor control device equipped with a detector that detects the rotation angle of a rotor, and rotates the rotor by supplying power to a brushless motor through vector control using a rotation angle detection value, which is the rotation angle of the rotor detected by the detector. The motor control device includes a command voltage derivation unit that derives a d-axis voltage command value that is a command value of a voltage component in a d-axis direction on a rotating coordinate of the vector control while the rotor is rotating, and a q-axis voltage command value that is a command value of a voltage component in a q-axis direction on the rotating coordinate, a current derivation unit that derives a d-axis current that is a current component in the d-axis direction and a q-axis current that is a current component in the q-axis direction while the rotor is rotating, and an error derivation unit that derives a rotation angle difference that is an error between an actual value of the rotation angle of the rotor and the rotation angle detection value, based on rotation angle-related information that is information obtained from the rotation angle detection value, the d-axis voltage command value, the q-axis voltage command value, and the d-axis current and the q-axis current.

[0006] A motor control device for solving the above problem is a motor control device equipped with a detector for detecting a rotation angle of a rotor, and a device for rotating the rotor by supplying power to a brushless motor by vector control using a rotation angle detection value that is the rotation angle of the rotor detected by the detector. The motor control device includes a command voltage derivation unit that derives a d-axis voltage command value that is a command value of a voltage component in the d-axis direction on a rotation coordinate system of the vector control, an AC voltage superposition unit that superposes a high-frequency AC voltage on the d-axis voltage command value, a high-frequency current extraction unit that extracts a high-frequency current that is a current component corresponding to the AC voltage from a q-axis current that is a current component in the q-axis direction on the rotation coordinate system, and an error derivation unit that derives a rotation angle difference that is an error between an actual value of the rotation angle of the rotor and the rotation angle detection value based on rotation angle-related information that is information obtained from the rotation angle detection value and the high-frequency current. Effect of the Invention

[0007] The above motor control device can advantageously derive the error between the actual value and the detected value of the rotor rotation angle without necessarily requiring the rotor to rotate in both the forward and reverse directions. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a configuration diagram showing a motor control device according to a first embodiment and a brushless motor controlled by the motor control device. [Diagram 2] FIG. 2 is a diagram showing an example of the relationship between an estimated d-axis, an estimated q-axis, an actual d-axis, and an actual q-axis on a rotating coordinate system of vector control. [Diagram 3] FIG. 3 is a diagram showing an example of the relationship between the detected value of the rotation angle of the rotor included in the brushless motor of FIG. 1 and the axial phase deviation. [Figure 4] FIG. 4 is a configuration diagram showing a motor control device according to the second embodiment and a brushless motor controlled by the motor control device. [Diagram 5] FIG. 5 is a diagram showing the relationship between the axial phase deviation and the high-frequency current. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (First embodiment) A first embodiment of a motor control device will be described below with reference to FIGS. 1 illustrates a brushless motor 100 and a motor control device 10 applied to the brushless motor 100. Hereinafter, the brushless motor 100 will be simply referred to as the "motor 100." The motor control device 10 will be simply referred to as the "control device 10."

[0010] <Motor configuration> The motor 100 includes a rotor 101 provided with a permanent magnet. The motor 100 is an embedded magnet type synchronous motor in which the permanent magnet is embedded inside the rotor 101. The rotor 101 has salient poles. The motor 100 includes a U-phase coil 105, a V-phase coil 106, and a W-phase coil 107. The motor 100 is used, for example, as a power source for an electric cylinder that discharges brake fluid in an on-vehicle brake device.

[0011] <Control device> The control device 10 is equipped with a rotation angle sensor 120 that detects the rotation angle of the rotor 101. This rotation angle sensor 120 corresponds to a "detector." Examples of the rotation angle sensor 120 include a resolver and an encoder. The rotation angle of the rotor 101 detected by the rotation angle sensor 120 is referred to as a "rotation angle detection value θ."

[0012] The control device 10 rotates the rotor 101 by supplying power to the motor 100 through vector control using the rotation angle detection value θ. The vector control is a control that adjusts a current component in the direction of the d-axis and a current component in the direction of the q-axis on the rotation coordinate system of the vector control. The d-axis is a control axis that extends in the direction of the magnetic flux axis of the permanent magnet. The q-axis is a control axis that extends in the torque direction and is perpendicular to the d-axis.

[0013] FIG. 2 shows a rotating coordinate system. In the rotating coordinate system, a control axis estimated to be the d-axis is called the "estimated d-axis," and a control axis estimated to be the q-axis is called the "estimated q-axis." On the other hand, in the rotating coordinate system, an actual d-axis is called the "real d-axis," and an actual q-axis is called the "real q-axis." The phase difference between the direction of the estimated d-axis and the direction of the actual d-axis is called the "axis phase deviation Δθ."

[0014] As shown in FIG. 1, the control device 10 rotates the rotor 101 by inputting signals based on a command value for a current component in the d-axis direction and a command value for a current component in the q-axis direction to a plurality of coils 105-107.

[0015] The control device 10 includes an inverter 11 and an electronic control device 20 . <Inverter> The inverter 11 has a plurality of switching elements that are operated by power supplied from a power source. The inverter 11 generates a U-phase signal, a V-phase signal, and a W-phase signal by turning on / off the switching elements based on a command from the electronic control device 20, i.e., a U-phase voltage command value VU*, a V-phase voltage command value VV*, and a W-phase voltage command value VW*, which will be described later. Specifically, the inverter 11 generates a U-phase signal based on the U-phase voltage command value VU*, and inputs the U-phase signal to a U-phase coil 105. The inverter 11 generates a V-phase signal based on a V-phase voltage command value VV*, and inputs the V-phase signal to a V-phase coil 106. The inverter 11 generates a W-phase signal based on a W-phase voltage command value VW*, and inputs the W-phase signal to a W-phase coil 107.

[0016] The U-phase voltage command value VU* is a command value for a voltage to be applied to the U-phase coil 105. The V-phase voltage command value VV* is a command value for a voltage to be applied to the V-phase coil 106. The W-phase voltage command value VW* is a command value for a voltage to be applied to the W-phase coil 107.

[0017] <Electronic control device> The electronic control device 20 has an execution device and a storage device. An example of the execution device is a CPU. The storage device stores a control program executed by the execution device. The execution device executes the control program, causing the electronic control device 20 to derive a U-phase voltage command value VU*, a V-phase voltage command value VV*, and a W-phase voltage command value VW*.

[0018] <Functional configuration of electronic control unit> The electronic control device 20 functions as a plurality of functional units for driving the motor 100 as a result of the execution device executing the control program. The plurality of functional units include, for example, a command current derivation unit 21, a command voltage derivation unit 23, a two-phase / three-phase conversion unit 25, a three-phase / two-phase conversion unit 27, an error derivation unit 29, a learning unit 31, and a rotation angle detection value correction unit 33.

[0019] The command current derivation unit 21 derives a d-axis current command value Id* and a q-axis current command value Iq* based on the torque command value TR*. The torque command value TR* is a command value for the output torque of the motor 100. The d-axis current command value Id* is a command value for the current component in the estimated d-axis direction. The q-axis current command value Iq* is a command value for the current component in the estimated q-axis direction.

[0020] The command voltage derivation unit 23 derives a d-axis voltage command value Vd* and a q-axis voltage command value Vq*. The d-axis voltage command value Vd* is a command value of a voltage component in the direction of the estimated d-axis. The q-axis voltage command value Vq* is a command value of a voltage component in the direction of the estimated q-axis. For example, the command voltage derivation unit 23 derives the d-axis voltage command value Vd* by feedback control based on the d-axis current command value Id* and the d-axis current Id. The command voltage derivation unit 23 derives the q-axis voltage command value Vq* by feedback control based on the q-axis current command value Iq* and the q-axis current Iq. Of the current vectors generated on the rotating coordinate system, the current component in the direction of the estimated d-axis is the d-axis current Id, and the current component in the direction of the estimated q-axis is the q-axis current Iq.

[0021] The two-phase / three-phase conversion unit 25 converts the d-axis voltage command value Vd* and the q-axis voltage command value Vq* into a U-phase voltage command value VU*, a V-phase voltage command value VV*, and a W-phase voltage command value VW* based on the rotation angle of the rotor 101. The two-phase / three-phase conversion unit 25 adopts a rotation angle correction value θc derived by a rotation angle detection value correction unit 33 (described later) or a rotation angle detection value θ as the rotation angle of the rotor 101. For example, when the learning of the rotation angle correction value θc is insufficient, the two-phase / three-phase conversion unit 25 adopts the rotation angle detection value θ as the rotation angle of the rotor 101. Also, for example, when the learning of the rotation angle correction value θc becomes sufficient, the two-phase / three-phase conversion unit 25 adopts the rotation angle correction value θc as the rotation angle of the rotor 101.

[0022] The two-phase / three-phase converter 25 may always use the rotation angle correction value θc as the rotation angle of the rotor 101. As described above, in this embodiment, the multiple voltage command values ​​VU*, VV*, VW* are each derived based on the rotation angle correction value θc or the rotation angle detection value θ. Then, the motor 100 is driven by operating the inverter 11 based on these multiple voltage command values ​​VU*, VV*, VW*. The rotation angle correction value θc is a value according to the rotation angle detection value θ. Therefore, the two-phase / three-phase conversion unit 25 and the inverter 11 constitute an example of a "control unit 35" that controls power supply to the motor 100 by vector control using the rotation angle detection value θ.

[0023] The three-phase / two-phase conversion unit 27 converts the U-phase current IU, the V-phase current IV, and the W-phase current IW into a d-axis current Id and a q-axis current Iq based on the rotation angle of the rotor 101. In this embodiment, the three-phase / two-phase conversion unit 27 corresponds to a "current derivation unit" that derives the d-axis current Id and the q-axis current Iq.

[0024] The three-phase / two-phase conversion unit 27 adopts the rotation angle correction value θc derived by a rotation angle detection value correction unit 33 (described later) or the rotation angle detection value θ as the rotation angle of the rotor 101. For example, when the learning of the rotation angle correction value θc is insufficient, the three-phase / two-phase conversion unit 27 adopts the rotation angle detection value θ as the rotation angle of the rotor 101. Also, for example, when the learning of the rotation angle correction value θc becomes sufficient, the three-phase / two-phase conversion unit 27 adopts the rotation angle correction value θc as the rotation angle of the rotor 101.

[0025] The three-phase / two-phase converter 27 may always use the rotation angle correction value θc as the rotation angle of the rotor 101. The error derivation unit 29 derives an axial phase deviation Δθ between the direction of the actual d-axis and the direction of the estimated d-axis. In this embodiment, vector control is performed using the rotation angle detection value θ. Therefore, the axial phase deviation Δθ corresponds to a "rotation angle difference" that is an error between the rotation angle detection value θ and the actual value of the rotation angle.

[0026] The error derivation unit 29 derives the shaft phase deviation Δθ as a rotation angle difference by the extended induced voltage method. In this case, the error derivation unit 29 derives the shaft phase deviation Δθ based on rotation angle related information obtained from the rotation angle detection value θ, the d-axis voltage command value Vd*, the q-axis voltage command value Vq*, the d-axis current Id, and the q-axis current Iq.

[0027] When the rotor 101 rotates due to the power supply to the motor 100 by vector control, an induced voltage Em is generated as shown in FIG. 2. The induced voltage Em is a voltage component in the direction of the actual q-axis. The component of the induced voltage Em in the direction of the estimated d-axis is "Em·sinΔθ". The component of the induced voltage Em in the direction of the estimated q-axis is "Em·cosΔθ". Therefore, the d-axis voltage command value Vd* can be expressed by the following relational expression (D1), and the q-axis voltage command value Vq* can be expressed by the following relational expression (D2). In the relational expressions (D1) and (D2), "R" is the winding resistance, "Ld" is the inductance in the direction of the d-axis, "Lq" is the inductance in the direction of the q-axis, and "ωe" is the estimated angular velocity. The estimated angular velocity ωe is derived based on the rotation angle detection value θ. Therefore, in this embodiment, the estimated angular velocity ωe corresponds to "rotation angle related information".

[0028]

number

[0029]

number

[0030] The learning unit 31 learns the relationship between the rotation angle detection value θ and the shaft phase deviation Δθ based on the shaft phase deviation Δθ. Hereinafter, the relationship between the rotation angle detection value θ and the shaft phase deviation Δθ learned by the learning unit 31 will be referred to as the "rotation angle relationship." The learning process of the rotation angle relationship by the learning unit 31 will be described later.

[0031] The rotation angle detection value correction unit 33 derives a rotation angle correction value θc by correcting the rotation angle detection value θ using the rotation angle relationship. For example, the rotation angle detection value correction unit 33 derives a shaft phase deviation Δθ corresponding to the rotation angle detection value θ based on the rotation angle relationship. Then, the rotation angle detection value correction unit 33 derives the sum of the rotation angle detection value θ and the shaft phase deviation Δθ as the rotation angle correction value θc.

[0032] <Learning process for rotation angle relationships> The learning process of the rotation angle relationship will be described with reference to Fig. 3. Fig. 3 shows an example of the relationship between the rotation angle detection value θ and the axial phase deviation Δθ when the rotor 101 is rotated by power supply to the motor 100 by vector control.

[0033] The learning unit 31 rotates the rotor 101 so that the detected rotation angle value θ changes by "2·m·π", thereby acquiring the transition of the axial phase deviation Δθ with respect to the change in the detected rotation angle value θ as shown in FIG. 3. Then, the learning unit 31 learns the rotation angle relationship. Here, "m" is a positive number equal to or greater than 1. The example shown in FIG. 3 is the relationship between the detected rotation angle value θ and the axial phase deviation Δθ when "m" is 1.

[0034] The learning unit 31 performs a Fourier series expansion of the axial phase deviation Δθ for each rotation angle detection value θ. For example, the learning unit 31 derives Fourier coefficients up to the second order of the period of the rotation angle detection value θ. That is, the learning unit 31 performs a Fourier series expansion of the relationship between the rotation angle detection value θ and the axial phase deviation Δθ in an interval that is an integer multiple of the period of the rotation angle detection value θ. Calculation formulas (D4) and (D5) for deriving the Fourier coefficients are shown below. In the calculation formulas (D4) and (D5), "f(θ)" is the axial phase deviation Δθ. "Z" is the integral value of the rotation angle detection value θ. "n" is a positive number equal to or greater than 0, and is desirably set to an order that matches the error characteristics of the sensor (i.e., the detector 120).

[0035]

number

[0036] Then, the rotation angle detection value correction unit 33 can derive the axial phase deviation Δθ corresponding to the rotation angle detection value θ at that time by using the following relational expression (D6).

[0037]

number

[0038] The electronic control device 20 sets the direction of the estimated d-axis and the direction of the estimated q-axis according to the rotation angle detection value θ. When there is no deviation between the actual value of the rotation angle and the rotation angle detection value θ, the direction of the estimated d-axis coincides with the direction of the actual d-axis, and the direction of the estimated q-axis coincides with the direction of the actual q-axis. However, in reality, due to an assembly error of the rotation angle sensor 120, etc., there occurs some deviation between the actual value of the rotation angle and the rotation angle detection value θ. Therefore, as shown in FIG. 2, for example, an axis phase deviation Δθ, which is an error between the direction of the estimated d-axis and the direction of the actual d-axis, occurs as a rotation angle difference, which is an error between the actual value of the rotation angle and the rotation angle detection value θ.

[0039] When the rotor 101 rotates as described above, an induced voltage Em is generated. Therefore, the electronic control device 20 derives the axis phase deviation Δθ as the rotation angle difference by substituting the estimated angular velocity ωe, the d-axis voltage command value Vd*, the q-axis voltage command value Vq*, the d-axis current Id, and the q-axis current Iq into the above relational expression (D3).

[0040] The electronic control device 20 derives the shaft phase deviation Δθ by utilizing the fact that an induced voltage Em is generated when the rotor 101 is rotated. Therefore, in order to derive the shaft phase deviation Δθ, the electronic control device 20 does not need to use both a parameter obtained by rotating the rotor 101 in the forward direction and a parameter obtained by rotating the rotor 101 in the reverse direction. Therefore, the motor control device 10 can derive the error between the actual value and the detected value of the rotation angle without necessarily rotating the rotor 101 in both the forward and reverse directions.

[0041] In this embodiment, the shaft phase deviation Δθ is derived when the motor rotation speed Nmt is equal to or higher than a reference rotation speed in order to generate a relatively large induced voltage Em. Therefore, the electronic control device 20 can accurately derive the shaft phase deviation Δθ.

[0042] In this embodiment, the following effects can be further obtained. (1-1) The electronic control unit 20 performs vector control using the rotation angle detection value θ. In addition, the electronic control unit 20 derives the shaft phase deviation Δθ using the rotation angle detection value θ.

[0043] Another method of deriving the rotation angle correction value θc is to derive the rotation angle correction value θc from the deviation between the actual value of the rotation angle obtained by sensorless vector control and the rotation angle detection value θ. The sensorless vector control is a control method in which the actual value of the rotation angle is estimated without using the rotation angle detection value θ by performing feedback control so that the shaft phase deviation Δθ becomes a predetermined value, and the motor 100 is driven by vector control using the actual value of the rotation angle. The predetermined value is preferably 0 (zero).

[0044] However, when the rotation angle correction value θc is to be derived from the deviation, the rotation angle correction value θc cannot be derived unless the sensorless vector control is performed. This is because the actual value of the rotation angle cannot be derived unless the feedback control is performed so that the shaft phase deviation Δθ becomes a predetermined value. In addition, when the motor rotation speed Nmt is less than the reference rotation speed, the induced voltage Em is not so large, so that it is difficult to say that the derivation accuracy of the shaft phase deviation Δθ is high, and the control accuracy of the sensorless vector control is low. From the above, when the electronic control device 20 controls the motor 100, it is necessary to switch between the sensorless vector control and the vector control using the rotation angle detection value θ according to the motor rotation speed Nmt. Therefore, when the rotation angle correction value θc is to be derived from the deviation between the actual value of the rotation angle obtained from the sensorless vector control and the rotation angle detection value θ, the control becomes complicated due to the switching between the sensorless vector control and the vector control using the rotation angle detection value θ.

[0045] In this regard, in vector control using the detected rotation angle θ, the detected rotation angle θ or the rotation angle correction value θc is used to control the motor 100, while the detected rotation angle θ is input to error derivation unit 29, which is a part separate from the control of the motor 100, to derive the axial phase deviation Δθ. Therefore, the electronic control device 20 does not need to switch between controls as described above. Therefore, the motor control device 10 can increase the correction accuracy of the detected rotation angle θ while suppressing the complication of control.

[0046] (1-2) The electronic control unit 20 learns the above-mentioned rotation angle relationship, which is the relationship between the rotation angle detected value θ and the shaft phase deviation Δθ. The electronic control unit 20 derives the shaft phase deviation Δθ corresponding to the current rotation angle detected value θ based on the rotation angle relationship. Then, the electronic control unit 20 corrects the rotation angle detected value θ using this shaft phase deviation Δθ. Therefore, the electronic control unit 20 can improve the correction accuracy of the rotation angle detected value θ.

[0047] (1-3) For example, the electronic control device 20 learns the above rotation angle relationship by expanding, into a Fourier series, the axial phase deviation Δθ for each rotation angle detection value θ when the rotor 101 is rotated so that the rotation angle detection value θ changes by "2·m·π", that is, in an interval that is an integer multiple of the period of the rotation angle detection value θ. The electronic control device 20 can improve the learning accuracy of the rotation angle relationship by learning the above rotation angle relationship using the Fourier series expansion in this way. By using the Fourier series expansion to learn the rotation angle relationship, the information on the rotation angle relationship is in the form of a function of each order component. This makes it less susceptible to the influence of noise components even if some of the rotation angle detection values ​​θ during learning are included. In addition, by having the information on the rotation angle relationship in a functional form, the amount of data on the rotation angle relationship stored in the electronic control device 20 can be reduced compared to the case where information on the axial phase deviation Δθ is individually stored for each point of the rotation angle detection value θ. The electronic control device 20 then corrects the rotation angle detection value θ using such a rotation angle relationship, thereby improving the correction accuracy of the rotation angle detection value θ.

[0048] Second embodiment A second embodiment of a motor control device will be described with reference to Figures 4 and 5. Note that the second embodiment differs from the first embodiment in, for example, the method of deriving the shaft phase deviation. In the following description, the differences from the first embodiment will be mainly described, and the same reference numerals will be used to designate the same members as in the first embodiment, and duplicated description will be omitted.

[0049] 4 illustrates a brushless motor 100 and a motor control device 10A. Hereinafter, the motor control device 10A will be simply referred to as the "control device 10A." The control device 10A includes an inverter 11 and an electronic control device 20A.

[0050] <Electronic control device> Like the electronic control device 20, the electronic control device 20A has an execution device and a storage device.

[0051] <Functional configuration of electronic control unit> The electronic control device 20A functions as a plurality of functional units for driving the motor 100 by the execution device executing the control program in the storage device. The plurality of functional units include, for example, a command current derivation unit 21, a command voltage derivation unit 23, a two-phase / three-phase conversion unit 25, a three-phase / two-phase conversion unit 27, an AC voltage generation unit 41, an addition unit 43, a high-frequency current extraction unit 45, an error derivation unit 29A, and a rotation angle detection value correction unit 33A. The command current derivation unit 21, the command voltage derivation unit 23, the two-phase / three-phase conversion unit 25, and the three-phase / two-phase conversion unit 27 are the same as those in the first embodiment, and therefore detailed description thereof will be omitted.

[0052] The AC voltage generating unit 41 generates a high-frequency AC voltage Vdh*. When the AC voltage generating unit 41 generates the AC voltage Vdh*, the adder 43 superimposes the AC voltage Vdh* on the d-axis voltage command value Vd* derived by the command voltage derivation unit 23. That is, the adder 43 corresponds to the "AC voltage superimposition unit". When the AC voltage generating unit 41 generates the AC voltage Vdh*, the two-phase / three-phase conversion unit 25 derives the U-phase voltage command value VU*, the V-phase voltage command value VV*, and the W-phase voltage command value VW* based on the d-axis voltage command value Vd* on which the AC voltage Vdh* is superimposed. On the other hand, when the AC voltage generating unit 41 does not generate the AC voltage Vdh*, the two-phase / three-phase conversion unit 25 derives the U-phase voltage command value VU*, the V-phase voltage command value VV*, and the W-phase voltage command value VW* based on the d-axis voltage command value Vd* on which the AC voltage Vdh* is not superimposed.

[0053] Here, the AC voltage generating unit 41 determines the phase of the AC voltage to be superimposed on the d-axis voltage command value Vd* based on the rotation angle of the rotor 101. At this time, the AC voltage generating unit 41 adopts a rotation angle correction value θc derived by a rotation angle detection value correcting unit 33A described later, or a rotation angle detection value θ, as the rotation angle of the rotor 101. For example, when the learning of the rotation angle correction value θc is insufficient, the AC voltage generating unit 41 adopts the rotation angle detection value θ as the rotation angle of the rotor 101. Also, for example, when the learning of the rotation angle correction value θc becomes sufficient, the AC voltage generating unit 41 adopts the rotation angle correction value θc as the rotation angle of the rotor 101.

[0054] The AC voltage generating unit 41 may always use the rotation angle correction value θc as the rotation angle of the rotor 101. When the AC voltage Vdh* is superimposed on the d-axis voltage command value Vd*, the high-frequency current extraction unit 45 extracts a high-frequency current Iqh, which is a current component corresponding to the AC voltage Vdh*, from the q-axis current Iq. For example, the high-frequency current extraction unit 45 obtains the high-frequency current Iqh by passing the q-axis current Iq through a band-pass filter.

[0055] As described above, the rotor 101 has a saliency. Therefore, the inductance in the q-axis direction may be larger than the inductance in the d-axis direction. In this case, if the direction of the estimated d-axis differs from the direction of the real d-axis, when a voltage vector is generated in the direction of the estimated d-axis, a current vector is generated that is deflected toward the real d-axis side with respect to the voltage vector.

[0056] In more detail, when the estimated d-axis is at an angle to the real d-axis, if power is supplied to the motor 100 so that a voltage vector is generated in the direction of the estimated d-axis, a current vector is generated at an angle toward the real d-axis with respect to the estimated d-axis on the rotating coordinate system. Therefore, when the estimated d-axis is at an angle to the real d-axis, a high-frequency current Iqh, which is a current component in the direction of the estimated q-axis, is generated. The high-frequency current Iqh is a current vector generated in the direction of the estimated q-axis. In other words, the absolute value of the high-frequency current Iqh corresponds to the magnitude of the current component in the direction of the estimated q-axis. In addition, the positive or negative value of the high-frequency current Iqh represents the direction of the current component in the direction of the estimated q-axis, i.e., the positive or negative direction.

[0057] On the other hand, when the direction of the estimated d-axis coincides with the direction of the real d-axis, if power is supplied to the motor 100 so that a voltage vector is generated in the direction of the estimated d-axis, the current vector generated on the rotating coordinate system does not deflect with respect to the estimated d-axis. Therefore, when the estimated d-axis is not tilted with respect to the real d-axis, no current flows in the direction of the estimated q-axis. In other words, the magnitude of the high-frequency current Iqh becomes 0 (zero).

[0058] Fig. 5 shows the transition of the high-frequency current Iqh when the axial phase deviation Δθ between the estimated d-axis and the real d-axis is continuously changed while a voltage vector is generated on the estimated d-axis. As shown in Fig. 5, the positive / negative state of the high-frequency current Iqh and the absolute value of the high-frequency current Iqh change according to the change in the axial phase deviation Δθ.

[0059] Returning to Fig. 4, the error derivation unit 29A derives the axial phase deviation Δθ. In this embodiment, vector control is performed using the detection value of the rotation angle sensor 120. Therefore, the axial phase deviation Δθ corresponds to a rotation angle difference that is an error between the rotation angle detection value θ, which is the detection value of the rotation angle sensor 120, and the actual value of the rotation angle.

[0060] The error derivation unit 29A derives the axial phase deviation Δθ by a disturbance injection method. In this case, the error derivation unit 29A derives the axial phase deviation Δθ based on rotation angle related information, which is information obtained from the rotation angle detection value θ, and the high-frequency current Iqh. Specifically, the error derivation unit 29A derives the axial phase deviation Δθ based on the rotation angle detection value θ, the absolute value of the high-frequency current Iqh, and the positive or negative value of the high-frequency current Iqh by utilizing the relationship between the axial phase deviation Δθ and the high-frequency current Iqh shown in FIG. 5.

[0061] When the AC voltage Vdh* is superimposed on the d-axis voltage command value Vd*, the error derivation unit 29A repeatedly executes the process of deriving the axial phase deviation Δθ for each predetermined calculation cycle. The rotation angle detection value correction unit 33A derives the rotation angle correction value θc by correcting the rotation angle detection value θ. For example, the rotation angle detection value correction unit 33A derives the sum of the latest value of the axial phase deviation Δθ derived by the error derivation unit 29A and the rotation angle detection value θ as the rotation angle correction value θc.

[0062] <Actions and Effects of the Present Embodiment> The electronic control device 20A rotates the rotor 101 by supplying power to the motor 100 through vector control. At this time, the electronic control device 20A uses a rotation angle detection value θ as the rotation angle of the rotor 101.

[0063] The electronic control device 20A sets the direction of the estimated d-axis and the direction of the estimated q-axis according to the rotation angle detection value θ. When there is no deviation between the actual value of the rotation angle and the rotation angle detection value θ, the direction of the estimated d-axis coincides with the direction of the actual d-axis, and the direction of the estimated q-axis coincides with the direction of the actual q-axis. However, in reality, due to an assembly error of the rotation angle sensor 120 or the like, there is some deviation between the actual value of the rotation angle and the rotation angle detection value θ. Therefore, an axis phase deviation Δθ, which is an error between the direction of the estimated d-axis and the direction of the actual d-axis, occurs as a rotation angle difference, which is an error between the actual value of the rotation angle and the rotation angle detection value θ.

[0064] The electronic control device 20A superimposes the high-frequency AC voltage Vdh* on the d-axis voltage command value Vd*. In this case, the q-axis current Iq contains a current component corresponding to the AC voltage Vdh*. Therefore, the electronic control device 20A extracts the high-frequency current Iqh, which is the current component corresponding to the AC voltage Vdh*, from the q-axis current Iq. Then, the electronic control device 20A derives the axis phase deviation Δθ based on the rotation angle detection value θ and the high-frequency current Iqh.

[0065] The electronic control device 20A derives the shaft phase deviation Δθ by using the AC voltage Vdh* obtained when the AC voltage Vdh* is superimposed on the d-axis voltage command value Vd*. Therefore, in order to derive the shaft phase deviation Δθ, the electronic control device 20A does not need to use both the parameters obtained by rotating the rotor 101 in the forward direction and the parameters obtained by rotating the rotor 101 in the reverse direction. Therefore, the control device 10A can derive the error between the actual value and the detected value of the rotation angle without necessarily rotating the rotor 101 in both the forward direction and the reverse direction.

[0066] In this embodiment, in addition to the effect (1-1) of the first embodiment, the following effect can be obtained. (2-1) The electronic control device 20A derives the rotation angle correction value θc by correcting the rotation angle detection value θ using the latest value of the shaft phase deviation Δθ. In this case, the electronic control device 20A does not need to have the function of the learning unit 31 as described in the first embodiment. Therefore, the control device 10A can correct the rotation angle detection value θ while suppressing an increase in the calculation load of the electronic control device 20A.

[0067] (Example of change) The above-described embodiments may be modified as follows: The above-described embodiments and the following modifications may be combined with each other to the extent that they are not technically inconsistent.

[0068] In the first embodiment, the electronic control device 20 learns the above rotation angle relationship in a state where the rotor 101 is rotated so that the rotation angle detection value θ changes by 2π. That is, "m" is set to 1, but this is not limited to this. "m" may be set to a positive number equal to or greater than 2. That is, it is sufficient to be able to acquire parameters for a number that is a multiple of 2π.

[0069] In the above first embodiment, the electronic control device 20 may rotate the rotor 101 in both the forward rotation direction and the reverse rotation direction, as long as it can acquire the rotation angle detection value θ and the axial phase deviation Δθ for 2·m·π.

[0070] In the first embodiment, the electronic control unit 20 acquires the transition of the shaft phase deviation Δθ corresponding to the change in the rotation angle detection value θ on the condition that the motor rotation speed Nmt is equal to or greater than the reference rotation speed, but this is not limited to the above. For example, the electronic control unit 20 may acquire the transition of the shaft phase deviation Δθ corresponding to the change in the rotation angle detection value θ when the motor rotation speed Nmt is equal to or greater than the reference rotation speed and the rate of change of the motor rotation speed Nmt is equal to or less than a predetermined rate.

[0071] In the first embodiment, the electronic control unit 20 may learn the rotation angle relationship using a method other than the Fourier series expansion. In the second embodiment, the electronic control unit 20A may have a function as the learning unit 31. In this case, the electronic control unit 20A can learn the rotation angle relationship. Therefore, the electronic control unit 20A can derive the shaft phase deviation Δθ corresponding to the current rotation angle detection value θ based on the rotation angle relationship.

[0072] In the first embodiment, the electronic control unit 20 does not need to have the function of the learning unit 31. In this case, the electronic control unit 20 can derive the rotation angle correction value θc by correcting the rotation angle detection value θ using the latest value of the shaft phase deviation Δθ.

[0073] If the absolute value of the shaft phase deviation Δθ is too large, there is a possibility that some abnormality has occurred in the rotation angle sensor 120. Therefore, in the above-described embodiments, the electronic control device 20, 20A may determine whether or not an abnormality has occurred in the rotation angle sensor 120 based on the shaft phase deviation Δθ. In this case, the electronic control device 20, 20A has, as a functional unit, an abnormality determination unit that determines whether or not the rotation angle sensor 120 is abnormal based on the shaft phase deviation Δθ. The abnormality determination unit may determine that the rotation angle sensor 120 is abnormal when the absolute value of the shaft phase deviation Δθ is equal to or greater than a threshold value, and may determine that the rotation angle sensor 120 is not abnormal when the absolute value of the shaft phase deviation Δθ is less than the threshold value.

[0074] In the above embodiments, the electronic control units 20 and 20A may selectively use sensorless vector control and vector control using the rotation angle detection value θ. The electronic control device 20, 20A may be configured as a circuit including one or more processors operating according to a computer program, one or more dedicated hardware circuits such as dedicated hardware for performing at least some of the various processes, or a combination of these. An example of the dedicated hardware is an application specific integrated circuit (ASIC). The processor includes a CPU and memory such as RAM and ROM, and the memory stores program code or instructions configured to cause the CPU to perform processes. The memory, i.e., the storage medium, includes any available medium accessible by a general-purpose or dedicated computer.

[0075] The motor 100 to which the motor control device 10, 10A is applied may be a power source for an actuator other than an on-vehicle brake device. <Other technical ideas> Next, the technical ideas that can be understood from the above embodiment and modified examples will be described.

[0076] [Additional Note 1] It is preferable to include a rotation angle detection value correction unit that corrects the rotation angle detection value based on the rotation angle difference. [Additional Note 2] The device may further include an abnormality determination unit that determines whether or not the detector is abnormal based on the rotation angle difference.

[0077] The term "at least one" used herein means "one or more" of the desired options. As an example, the term "at least one" used herein means "only one option" or "both of two options" if the number of options is two. As another example, the term "at least one" used herein means "only one option" or "any combination of two or more options" if the number of options is three or more. [Explanation of symbols]

[0078] 10, 10A...Control device (motor control device) 11…Inverter 20, 20A...Electronic control device 23...Command voltage derivation section 25...2-phase / 3-phase conversion section 27...3-phase / 2-phase conversion section (an example of a current lead-out section) 29,29A…Error derivation section 31…Learning Department 33, 33A…Rotation angle detection value correction unit 35...Control section 43...Adder unit (an example of an AC voltage superimposing unit) 45...High frequency current extraction section 100...Motor (brushless motor) 101...Rotor 120...Rotation angle sensor (detector)

Claims

1. A motor control device equipped with a detector for detecting a rotation angle of a rotor, the motor control device rotating the rotor by supplying power to a brushless motor through vector control using a rotation angle detection value, which is the rotation angle of the rotor detected by the detector, a command voltage derivation unit that derives a d-axis voltage command value that is a command value of a voltage component in a d-axis direction on a rotating coordinate system of the vector control while the rotor is rotating, and a q-axis voltage command value that is a command value of a voltage component in a q-axis direction on the rotating coordinate system; a current deriving unit that derives a d-axis current, which is a current component in a d-axis direction, and a q-axis current, which is a current component in a q-axis direction, when the rotor is rotating; an error derivation unit that derives a rotation angle difference, which is an error between an actual value of the rotation angle of the rotor and the rotation angle detection value, based on rotation angle-related information that is information obtained from the rotation angle detection value, the d-axis voltage command value, the q-axis voltage command value, and the d-axis current and the q-axis current. Motor control device.

2. A motor control device equipped with a detector for detecting a rotation angle of a rotor, the motor control device rotating the rotor by supplying power to a brushless motor through vector control using a rotation angle detection value, which is the rotation angle of the rotor detected by the detector, a command voltage derivation unit that derives a d-axis voltage command value that is a command value of a voltage component in a d-axis direction on a rotation coordinate system of the vector control; an AC voltage superposition unit that superposes a high-frequency AC voltage on the d-axis voltage command value; a high-frequency current extraction unit that extracts a high-frequency current, which is a current component corresponding to the AC voltage, from a q-axis current, which is a current component in a q-axis direction on the rotating coordinate system; an error derivation unit that derives a rotation angle difference, which is an error between an actual value of the rotation angle of the rotor and the rotation angle detection value, based on rotation angle-related information, which is information obtained from the rotation angle detection value, and the high-frequency current. Motor control device.

3. a learning unit configured to learn the relationship between the rotation angle detection value and the rotation angle difference by expanding the relationship between the rotation angle detection value and the rotation angle difference in a Fourier series in an interval that is an integer multiple of the period of the rotation angle detection value; The motor control device according to claim 1 or 2.

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