Inductance measurement device and inductance measurement method

Abstract

An inductance measurement device (1) for measuring the inductance of a plurality of sets of multiphase AC machines (2) is provided with: a voltage application means (10) for applying a voltage to the plurality of sets of multiphase AC machines (2) by using one of a plurality of sets of windings as a self-measurement set and using a set of windings other than the self-measurement set as an interference measurement set; applying a measurement voltage based on the measurement voltage command value and not driving the multi-group multi-phase AC machine (2) to the self-measurement group; a voltage application means (20) that applies, to the interference measurement group, an interference measurement voltage that does not drive the multi-group multi-phase AC machine (2) on the basis of an interference measurement voltage command value for controlling the current of the interference measurement group to zero; and an inductance calculation means (30) for calculating the self-inductance of the self-test group and the mutual inductance from the self-test group to the interference measurement group on the basis of the current of the self-test group and the interference measurement voltage command value.

Description

Technical Field

[0001] This invention relates to an inductance measuring device and an inductance measuring method. Background Technology

[0002] Multiphase AC motors with multiple independent winding groups within a single motor offer several advantages. For example, by multiplying identical winding groups, they can handle larger capacities and torques, enabling individual control of each winding group and reducing motor harmonics. Furthermore, multiplying the windings in orthogonal directions allows each winding group to form the stator of a multi-axis actuator, resulting in a multi-degree-of-freedom actuator structure that directly drives multiple axes. Due to these advantages, multiphase AC motors are expected to contribute to the high output and miniaturization of industrial equipment.

[0003] It is known that in multi-phase AC motors like the one described above, magnetic coupling occurs between winding groups, affecting each other. Specifically, the following problems exist: control performance deteriorates due to inter-group interference caused by magnetic coupling, leading to reduced control response and current ripple. These problems can be eliminated by pre-calculating the mutual inductance related to the interfering magnetic flux through measurement, and then using this mutual inductance to neutralize the magnetic interference between winding groups within the controller that controls the multi-phase AC motor.

[0004] Even when the mutual inductance is calculated through prior analysis, the values ​​may not always be consistent due to manufacturing errors in the actual AC motor. In particular, in motors with multiple windings in orthogonal directions, which function as multi-degree-of-freedom actuators, manufacturing errors in the coils that cause phase shifts can lead to interference with other windings, such as leakage flux from one winding group. Therefore, the interference flux may sometimes be uneven. Consequently, the mutual inductance Mzθ from one winding group z to another winding group θ and its opposite Mθz may not always be consistent. It is preferable to be able to measure the interference inductance when voltages are applied to each winding group separately.

[0005] The applicant disclosed the following method: by applying a high-frequency rotating voltage having a fundamental frequency that is sufficiently higher than the synchronous rotation frequency of the synchronous motor, the self-inductance is measured while suppressing the rotation and vibration of the synchronous motor (for example, see Patent Document 1).

[0006] In addition, the following method is disclosed: the stator flux on the dq coordinate axis is estimated based on the equivalent value of the stator current, the equivalent value of the stator voltage and the electric angular velocity of the driven dual three-phase synchronous motor, and the inductance is calculated and identified based on the stator flux and the stator current (for example, see Patent Document 2).

[0007] Patent Document 1: Japanese Patent No. 5523584

[0008] Patent Document 2: Japanese Patent Application Publication No. 2020-184868 Summary of the Invention

[0009] Patent Document 1 discloses a technology that can measure self-inductance without rotating the synchronous motor, but it does not disclose an application to multi-phase AC motors. Therefore, it uses a voltage command value set by itself as the voltage value used in inductance calculation, and thus does not address the situation of measuring the mutual inductance of winding groups without applied voltage in multi-phase AC motors.

[0010] On the other hand, the technology disclosed in Patent Document 2 enables mutual inductance measurement of a dual-winding PMSM (Permanent Magnet Synchronous Motor) as a multi-phase AC motor without setting up a voltage detector by utilizing its voltage command value in drive control. However, since it utilizes the electric angular velocity of the rotor, the prerequisite is that the AC motor is in a rotating drive state.

[0011] If the inductance is measured while the AC motor is rotating, there are limitations on the timing of the measurement. Therefore, a technique is sought to measure the mutual inductance of multiple multiphase AC motors without rotating the AC motor.

[0012] The present invention discloses a technique for solving the above-mentioned problems, and its object is to provide an inductance measuring device that can measure the mutual inductance of multiple sets of multiphase AC motors without rotating the AC motor.

[0013] The inductance measuring device of the present invention measures the inductance of a multi-phase AC motor having multiple multi-phase winding groups, wherein, The inductance measuring device has a voltage application unit for applying voltage and a current detection unit for detecting current for each of the multiple winding groups, and the inductance measuring device also has an inductance calculation unit for calculating inductance. One of the multiple winding groups is designated as the self-test group, and the winding groups other than the self-test group are designated as the interferometric measurement group. The voltage application unit of the self-test group applies a measurement voltage to the self-test group based on the measurement voltage command value without driving the multi-phase AC motors. The voltage application unit of the interferometric measurement group has a current controller. The voltage application unit of the interferometric measurement group applies an interferometric measurement voltage based on an interferometric measurement voltage command value that controls the current of the interferometric measurement group to 0, without driving the multiple sets of multiphase AC motors. The inductance calculation unit calculates the self-inductance of the self-test group and the mutual inductance from the self-test group to the interferometric measurement group based on the current detected by the current detection unit of the self-test group and the voltage command value for interferometric measurement.

[0014] The effects of the invention

[0015] According to the present invention, the mutual inductance of multiple sets of multiphase AC motors can be measured without rotating the AC motor. Attached Figure Description

[0016] Figure 1 This is a block diagram showing the structure of the inductance measuring device for the multi-phase AC motors involved in Embodiment 1.

[0017] Figure 2 This is a block diagram showing the structure of the inductance measuring device for the dual-group three-phase synchronous motor according to Embodiment 1.

[0018] Figure 3 This is a block diagram showing the structure of the voltage command generation unit in the interferometric measurement group according to Embodiment 1.

[0019] Figure 4 This is a block diagram showing the structure of the inductor operation unit according to Embodiment 1.

[0020] Figure 5 This is a flowchart illustrating the operation of the inductance measuring device for the dual-group three-phase synchronous motor involved in Embodiment 1.

[0021] Figure 6 This is a schematic diagram illustrating a structural example of a dual-group three-phase synchronous motor that is the object of measurement for an inductance measuring device according to embodiments 1 and 2.

[0022] Figure 7A This is a schematic diagram illustrating a structural example of a direct-acting rotary actuator that is the object of measurement in an inductance measuring device according to embodiments 1 and 2.

[0023] Figure 7B Viewed from the side Figure 7A An enlarged view of the stator winding assembly of a direct-acting rotary actuator.

[0024] Figure 8 This is a diagram illustrating an example of the hardware structure of the inductance measuring device according to embodiments 1 to 3. Detailed Implementation

[0025] Hereinafter, this embodiment will be described with reference to the accompanying drawings. Furthermore, in each drawing, the same reference numerals denote the same or equivalent parts.

[0026] Implementation Method 1

[0027] Hereinafter, the inductance measuring device of the multi-phase AC motor according to Embodiment 1 will be described with reference to the accompanying drawings.

[0028] <Structure of Inductance Measuring Device 1>

[0029] Figure 1 This is a block diagram illustrating the structure of the inductance measuring device for the multi-phase AC motors according to Embodiment 1. The inductance measuring device 1 measures the inductance of the multi-phase AC motors 2. The inductance measuring device 1 includes: a self-test group voltage application unit 10, which applies voltage to the self-test group; an interferometric measurement group voltage application unit 20, which applies voltage to the interferometric measurement group; and an inductance calculation unit 30. Here, if the number of winding groups is set to n (n is a natural number greater than or equal to 2), then there are n-1 interferometric measurement groups, denoted as interferometric measurement group voltage application units 20_1 to 20_n-1.

[0030] In Implementation 1, taking a dual-group three-phase synchronous motor as an example, the multi-group multiphase AC motor 2 is described. Therefore, there is one inductance measuring device 1, one self-test group, and one interferometric measurement group. Figure 2 This is a block diagram illustrating the structure of the inductance measuring device for the dual-group three-phase synchronous motor according to Embodiment 1. The first group of the dual-group three-phase synchronous motor 2A is designated as the self-test group, and the self-test group voltage application unit 10 is connected to the first group. The second group of the dual-group three-phase synchronous motor 2A is designated as the interferometric measurement group, and the interferometric measurement group voltage application unit 20 is connected to the second group.

[0031] Furthermore, in the following, values ​​related to the self-test group are denoted by the suffix _s, and values ​​related to the interferometric measurement group are denoted by the suffix _m. Additionally, values ​​related to the first group are denoted by the suffix _1, values ​​related to the second group by the suffix _2, values ​​related to the interference generated from the first group to the second group when a voltage is applied to the first group by the suffix _21, and values ​​related to the interference generated from the second group to the first group when a voltage is applied to the second group by the suffix _12.

[0032] Furthermore, the two axes in the fixed coordinate system are designated as the α-axis and β-axis, and the two axes in the rotating coordinate system are designated as the d-axis and q-axis. The d-axis is the reference direction in the rotating coordinate system. For example, in a synchronous machine with excitation, it is set as the direction of its excitation, and in a synchronous machine without excitation, such as a reluctance synchronous machine, it is set as the direction of its maximum or minimum inductance, etc.

[0033] exist Figure 2 In the self-test group voltage application unit 10, there is a voltage command generation unit 11, a power converter 12, and a current detector 13. The interferometric measurement group voltage application unit 20 has a voltage command generation unit 21, a power converter 22, and a current detector 23.

[0034] <Operation of the self-test group voltage application unit 10>

[0035] First, the operation of the self-test group voltage application unit 10 will be explained.

[0036] In the voltage command generation unit 11 of the self-test group voltage application unit 10, the measurement voltage command value V is generated. u_s、V v_s、V w_s, these measurement voltage command values ​​only aid in inductance measurement and do not drive the dual-group three-phase synchronous motor 2A. The voltage command generation unit 11 generates the measurement voltage command value V u_s、V v_s、V The w_s output is sent to the power converter 12. Additionally, in three-phase generalization, it is recorded as the measurement voltage command value V. uvw_s.

[0037] Here, the voltage command value V is used for measurement when generating the voltage command angular frequency ωh, the effective value of the voltage command for each phase Vh_s, and the phase difference between each phase of a three-phase AC voltage of 120°. The case of uvw_s will be explained. At this time, the setting values ​​of the measurement voltage command input to the voltage command generation unit 11 are the voltage command angular frequency ωh and the voltage command effective value Vh_s.

[0038] To avoid driving the dual-group three-phase synchronous motor 2A, the voltage command angular frequency ωh is set to an angular frequency that is sufficiently high to drive the dual-group three-phase synchronous motor 2A. The voltage command V used for measurement is... uvw_s is set to high-frequency rotating voltage. The voltage command angular frequency ωh should be as high as possible compared to the rated angular frequency. For example, it is sufficient to set it to be greater than or equal to 10 times. However, if the dual three-phase synchronous motor 2A is not driven due to the relationship with other parameters such as inertia, it can also be around 3 or 4 times.

[0039] The power converter 12, for example, uses PWM (Pulse Width Modulation) with a triangular wave as the carrier wave to transmit the measured voltage command V. u_s、V v_s、V w_s is transformed into the measurement voltages Vu_s, Vv_s, and Vw_s. That is, it functions as a voltage applicator, which follows the measurement voltage command V. u_s、V v_s、V The alternating voltage w_s is applied to the stator winding of the first group of the self-test group of the dual-group three-phase synchronous motor 2A. Furthermore, when referring to all three phases, it is denoted as the measuring voltage Vuvw_s.

[0040] The current detector 13 detects the three-phase current values ​​Iu_s, Iv_s, and Iw_s of the self-test group of the dual-group three-phase synchronous motor 2A and outputs them to the inductance calculation unit 30. Furthermore, when referring to all three phases, the three-phase current value is recorded as Iuvw_s.

[0041] <Structure and Operation of Voltage Application Unit 20 in Interferometric Measurement Group>

[0042] Figure 3 This is a block diagram illustrating the structure of the voltage command generation unit 21 in the interferometric measurement group voltage application unit 20 according to Embodiment 1. The voltage command generation unit 21 includes a coordinate transformer 24 that transforms a 3-axis structure into a 2-axis structure, a current controller 25, and a coordinate transformer 26 that transforms a 2-axis structure into a 3-axis structure.

[0043] Next, the operation of the voltage application unit 20 of the interferometric measurement group will be explained.

[0044] The current detector 23 detects the three-phase current values ​​Iu_m, Iv_m, and Iw_m of the interferometric measurement group of the dual-group three-phase synchronous motor 2A and outputs them to the coordinate transformer 24 of the voltage command generation unit 21. Furthermore, when referring to all three phases collectively, these are recorded as the three-phase current detection value Iuvw_m.

[0045] Input the three-phase current detection value Iuvw_m into the coordinate transformer 24, and transform the three-phase current detection value Iuvw_m into the current detection values ​​Iα_m and Iβ_m on the αβ axis of the stationary coordinate system through coordinate transformation.

[0046] The α-axis current detection value Iα_m and the β-axis current detection value Iβ_m, transformed by the coordinate transformer 24, are input to the current controller 25 via subtractors. The α-axis current command value I is input to the positive side of the subtractor to which the α-axis current detection value Iα_m is input. α_m, inputs the β-axis current command value I to the positive side of the subtractor that receives the β-axis current detection value Iβ_m. β_m. Here, the α-axis current command value I α_m and β axis current command values ​​I β_m is 0.

[0047] The current controller 25 pairs ensure that the α-axis current detection value Iα_m matches the α-axis current command value I. α_m is consistent, and the β-axis current detection value Iβ_m is consistent with the β-axis current command value I. β_m consistent voltage command value V α_m、V β_m is used for calculation. The current controller 25 transmits the α-axis voltage command value V. α_m and β-axis voltage command value V β_m is output to coordinate transformer 26.

[0048] Here, the current response angular frequency of the current controller 25 is set to be higher than the voltage command V measured in the self-test group. u_s、V v_s、V The voltage command angular frequency ωh used in the calculation of w_s is sufficiently high. The current response angular frequency is preferably set to be at least 2 to 3 times higher than the voltage command angular frequency ωh.

[0049] Accompanied by the measurement voltage command value V of the self-test group The applied voltage uvw_s generates an interference voltage with a voltage command angular frequency ωh in the interferometric measurement group, which is associated with the flux change of the interference flux from the self-test group. However, by controlling the current controller 25 to make the current value of the αβ axis zero, a voltage command is output to make the current zero to resist these interference voltages. At this time, by setting the response of the current controller 25 to be sufficiently high than the voltage command angular frequency ωh, it is possible to operate in a way that sufficiently attenuates the component of the voltage command angular frequency ωh of the current on the αβ axis. Therefore, the voltage command value Vα_m output from the current controller 25 at this time... Vβ_m The component of the voltage command angular frequency ωh can be used as the voltage when the current is 0, that is, the voltage in the open circuit state.

[0050] The α-axis voltage command value V input to coordinate transformer 26 α_m and β-axis voltage command value V β_m is transformed from a 2-axis stationary coordinate system into a three-phase voltage command value V through coordinate transformation. u_m、V v_m、V w_m is output to the inductor operation unit 30 and the power converter 22. Furthermore, in the case of three-phase operation, it is denoted as the three-phase voltage command value V. uvw_m. This is the three-phase voltage command value V. uvw_m is the voltage command value used for interferometry.

[0051] Like power converter 12, power converter 22 converts the three-phase voltage command value V using, for example, a PWM method with a triangular wave as the carrier wave. uvw_m is transformed into voltages Vu_m, Vv_m, and Vw_m. That is, it functions as a voltage applicator, which will follow the three-phase voltage command value V. u_m、V v_m、V An alternating voltage w_m is applied to the stator windings of the second group (interferometric measurement group) of the 2A dual-group three-phase synchronous motor. Furthermore, when referring to all three phases collectively, it is denoted as voltage Vuvw_m. This voltage Vuvw_m is the voltage used for interferometry.

[0052] <Structure and Operation of Inductor Operation Unit 30>

[0053] Figure 4 This is a block diagram showing the structure of the inductance calculation unit 30 according to Embodiment 1. The inductance calculation unit 30 includes a coordinate transformer 31 that transforms a 3-axis system into a 2-axis system, a fundamental component extractor 32, an inductance calculator 33, and an RMS value calculator 34.

[0054] Next, the operation of the inductor operation unit 30 will be explained.

[0055] Input the three-phase current detection value Iuvw_s of the self-test group and the three-phase voltage command value V of the interferometric measurement group into the inductance calculation unit 30. uvw_m, voltage command angular frequency ωh, and voltage command effective value Vh_s.

[0056] First, the three-phase current detection value Iuvw_s of the self-test group and the scanning phase angle ε are input to the coordinate transformer 31. The coordinate transformer 31 transforms the coordinates of the three-phase current detection value Iuvw_s into the current of the γδ axis, which rotates with the scanning phase angle ε and is based on the scanning phase angle ε. The reference direction, i.e., the γ axis current detection value Iγ_s(ε), is then calculated and output.

[0057] The fundamental component extractor 32 is input with the γ-axis current detection value Iγ_s(ε) and the voltage command angular frequency ωh. The fundamental component extractor 32 extracts the component Iγh_s(ε) containing the same frequency as the voltage command angular frequency ωh from the γ-axis current detection value Iγ_s(ε). This fundamental component extraction can be performed using any known technique, such as a bandpass filter. The fundamental component extractor 32 outputs the high-frequency component Iγh_s(ε) of the γ-axis current.

[0058] Input the three-phase voltage command value V of the interferometric measurement group into the effective value calculator 34. uvw_m. Effective value calculator for 34 pairs of three-phase voltage command values ​​V The effective value of the voltage command V of uvw_m h_m is calculated and the result is output to the inductance calculator 33. Furthermore, in Figure 4According to the three-phase voltage command value V The example given is uvw_m, which calculates the effective value of the voltage command. However, it can also be based on the αβ axis voltage command value V of the interferometric measurement group. α_m、V β_m is a structure for calculating the effective value of voltage commands.

[0059] Input the high-frequency component of the γ-axis current Iγh_s(ε), the voltage command angular frequency ωh, the set value of the effective value of the voltage command for measurement Vh_s, and the effective value of the voltage command V into the inductance calculator 33. h_m. The inductance calculator 33 uses the following formula (1) to calculate the γ-axis inductance Lγ_s(ε) of the self-test group of the dual-group three-phase synchronous motor 2A.

[0060]

Equation 1

[0061] Additionally, input the high-frequency component of the γ-axis current Iγh_s(ε) and the substitute value of the effective value of the interference voltage at this time, i.e., V, into the inductance calculator 33. h_m, therefore, the γ-axis interference inductance Mγ_m(ε) of the interferometric measurement group of the dual-group three-phase synchronous motor 2A from the self-test group can be calculated using the following formula (2) based on these values ​​and the voltage command angular frequency ωh.

[0062]

Equation 2

[0063] The above processing is one processing when the scanning phase angle ε is used. However, while changing the scanning phase angle ε from 0 [rad] to π [rad], the same processing is repeated. The γ-axis inductance Lγ_s(ε) (0≤ε≤π) of the self-test group and the γ-axis interference inductance Mγ_m(ε) (0≤ε≤π) from the self-test group to the interferometric measurement group are calculated in the inductance calculator 33 when the scanning phase angle ε is used.

[0064] Then, find the minimum and maximum values ​​of Lγ_s(ε), and define one of the maximum and minimum values ​​as the inductance Ld_s of the reference d-axis, and the other as the inductance Lq_s of the reference q-axis.

[0065] In addition, the minimum and maximum values ​​of the γ-axis interference inductance Mγ_s(ε) are determined. One of the maximum and minimum values ​​is defined as the interference inductance Md_s of the reference d-axis, and the other is defined as the interference inductance Mq_s of the reference q-axis.

[0066] Here, the number of groups is 2. The first group is designated as the self-test group, and the second group is designated as the interferometric measurement group. Therefore, the measured self-inductance is the self-inductance of the first group, and the mutual inductance is the mutual inductance from the first group to the second group. Thus, Ld_s=Ld_1, Lq_s=Lq_1, Md_m=Md_21, Mq_m=Mq_21 are defined.

[0067] <Flowchart of Inductance Measurement Operation>

[0068] Next, use Figure 5 The flowchart illustrates the process of inductance measurement operation using the inductance measurement device 1 in Embodiment 1.

[0069] First, in step ST1, the power converter 12 of the self-test group voltage application unit 10 will follow the measurement voltage command value V. The voltage Vuvw_s used for measuring uvw_s is applied to the first winding group, i.e., the self-test group, of the 2A dual-group three-phase synchronous motor. The frequency of the voltage applied to the self-test group is sufficiently high compared to the rated electrical angular frequency of the drive motor, so that the motor will not be driven even if the measuring voltage Vuvw_s is applied to the self-test group.

[0070] Next, in step ST2, the current detection value Iuvw_s is obtained by the current detector 13 of the self-test group voltage application unit 10, and the current detection value Iuvw_m is obtained by the current detector 23 of the interferometric measurement group voltage application unit 20.

[0071] Next, in step ST3, the power converter 22 of the interferometric measurement group voltage application unit 20 will follow the three-phase voltage command value V. The voltage Vuvw_m of uvw_m is applied to the second winding group of the 2A dual-group three-phase synchronous motor, i.e., the interferometric measurement group.

[0072] Accompanied by the measurement voltage command value V of the self-test group The applied voltage uvw_s generates an interference voltage with a voltage command angular frequency ωh in the interferometric measurement group, which is associated with the flux change of the interference magnetic flux from the self-test group. In the voltage command generation unit 21 of the interferometric measurement group voltage application unit 20, the three-phase voltage command value V is generated based on the αβ axis current after coordinate transformation of the current detection value Iuvw_m. `uvw_m` outputs a voltage command to counteract the interference voltage and reduce the current along the αβ axis to zero. Additionally, it generates the three-phase voltage command value V. The current response angular frequency of the uvw_m current controller 25 is set to be higher than the voltage command V measured in the self-test group. u_s、V v_s、V The voltage command angular frequency ωh used in the calculation of w_s is sufficiently high, even if the voltage V The uvw_m is applied to the second winding group of the dual-group three-phase synchronous motor 2A, which is the interferometric measurement group, and does not drive the motor.

[0073] Next, in step ST4, the three-phase current detection value Iuvw_s of the self-test group and the three-phase voltage command value V of the interferometric measurement group are input to the inductance calculation unit 30. uvw_m, voltage command angular frequency ωh, and voltage command effective value Vh_s, and set the scanning phase angle ε for calculating the γ-axis inductance Lγ_s(ε) of the self-test group and the γ-axis interference inductance Mγ_m(ε) from the self-test group of the interferometric group.

[0074] Next, in step ST5, the γ-axis inductance Lγ_s(ε) of the self-test group and the γ-axis interference inductance Mγ_m(ε) from the self-test group to the interferometric measurement group are calculated when the phase angle ε is used for scanning.

[0075] Next, in step ST6, to change the scanning phase angle ε from 0 [rad] to π [rad], the calculations of the γ-axis inductance Lγ_s(ε) of the self-test group and the γ-axis interference inductance Mγ_m(ε) from the self-test group to the interferometric group are performed, and it is determined whether the scanning phase angle ε has reached π [rad]. Steps ST4 to ST6 are repeated until the scanning phase angle ε reaches π [rad].

[0076] In step ST6, if it is determined that the calculation of the γ-axis inductance Lγ_s(ε) of the self-test group and the γ-axis interference inductance Mγ_m(ε) from the self-test group to the interferometric measurement group has been performed until the phase angle ε of the scan reaches π[rad], then proceed to step ST7.

[0077] In step ST7, the inductance Ld_s of the d-axis and the inductance Lq_s of the q-axis are determined based on the minimum and maximum values ​​of the γ-axis inductance Lγ_s(ε) of the self-test group. The interference inductance Md_s of the d-axis and the interference inductance Mq_s of the q-axis are determined based on the minimum and maximum values ​​of the γ-axis interference inductance Mγ_s(ε).

[0078] Here, the number of groups is 2, so it is defined as Ld_s=Ld_1, Lq_s=Lq_1, Md_m=Md_21, Mq_m=Mq_21.

[0079] Therefore, it is possible to calculate the self-inductance of the self-test group and the interference inductance from the self-test group to the interferometric measurement group together.

[0080] Furthermore, this explanation assumes that the self-test group of the dual-group three-phase synchronous motor 2A has saliency, and describes the determination of the maximum and minimum inductance caused by its saliency. However, in the absence of saliency, Lγ_s(ε) does not have maximum and minimum peak values, and Ld_s = Lq_s. As mentioned above, if it is known in advance that the self-test group of the dual-group three-phase synchronous motor 2A has no saliency or is so small as to be negligible, it is also possible to omit the process of changing the scanning phase angle ε from 0 [rad] to π [rad], and only perform the process at any point of the scanning phase angle ε [rad] to make Lγ_s = Ld_s = Lq_s, thereby omitting the repeated execution of steps ST4 to ST6.

[0081] The same applies to the interferometric measurement group of the aforementioned dual-group three-phase synchronous motor 2A. If it is known beforehand that the interferometric measurement group of the dual-group three-phase synchronous motor 2A has no salient polarity, or that its polarity is so small as to be negligible, the process of changing the scanning phase angle ε from 0 [rad] to π [rad] can be omitted. Instead, the process can be performed only at any point of the scanning phase angle ε [rad], making Mγ_s=Md_m=Md_m, thereby omitting the repeated execution of steps ST4 to ST6.

[0082] Furthermore, this example illustrates the measurement of the self-inductance of the first group and the interference inductance from the first group to the second group by defining the first group as the self-test group and the second group as the interferometric measurement group. However, by defining the second group as the self-test group and the first group as the interferometric measurement group, it is possible to independently determine the self-inductance Ld_m=Ld_2, Lq_m=Lq_2 of the second group and the interference inductance Md_s=Md_12, Mq_s=Mq_12 of the second group from the interference inductance from the first group to the second group.

[0083] Furthermore, this explanation uses a motor with two winding groups (2 winding groups) as an example. However, in motors with three or more winding groups, the method used is as follows: Figure 1 The diagram illustrates how a certain group is designated as the self-test group, and all other windings are designated as interferometric measurement groups. This allows for the calculation of self-inductance and interference inductance from the self-test group to all other interferometric measurement groups. Furthermore, by sequentially assigning each winding group to a self-test group and repeating this process, the interference inductance from each winding group to other winding groups outside the current group can be calculated individually. In other words, this can be achieved as long as the following method is followed... Figure 5The process can be as follows: after measuring the inductance by using one winding group from the multiple winding groups as a self-test group and the other winding groups as interferometric measurement groups, one other winding group from the multiple winding groups other than the one already selected as a self-test group is selected as an updated self-test group, and the winding groups other than the updated self-test group are selected as updated interferometric measurement groups to measure the inductance. This process of updating and measuring is performed sequentially by making all the winding groups self-test groups.

[0084] As described above, according to Embodiment 1, the inductance measuring device for measuring the inductance of multiple multiphase AC motors includes a voltage application unit for applying voltage and a current detection unit for detecting current for each of the multiple winding groups, and an inductance calculation unit for calculating the inductance. Furthermore, one of the multiple winding groups is designated as a self-test group, and the other winding groups are designated as interferometric measurement groups. The voltage application unit for the self-test group applies a measurement voltage based on a measurement voltage command value without driving the multiple multiphase AC motors. The voltage application unit for the interferometric measurement group has a current controller that applies an interferometric measurement voltage based on an interferometric measurement voltage command value that controls the current of the interferometric measurement group to 0 without driving the multiple multiphase AC motors. The inductance calculation unit calculates the self-inductance of the self-test group and the mutual inductance from the self-test group to the interferometric measurement group based on the current detected by the current detection unit of the self-test group and the interferometric measurement voltage command value. This structure allows for the measurement of self-inductance by applying a voltage command value to the self-test group that, without driving multiple multiphase AC motors, only facilitates inductance measurement. Simultaneously, by controlling the current in the interferometric measurement group to zero, the interference voltage generated in the interferometric measurement group can be obtained, thus enabling the acquisition of interference inductance. Furthermore, it has the following effect: the structure of a conventional AC motor control device, including a power converter but without a voltage detector, can be applied to an inductance measurement device capable of measuring interference inductance.

[0085] Furthermore, since the voltage command angular frequency used to generate the measurement voltage command value is set to a value that is sufficiently high as the drive angular frequency of the multi-phase AC motor, inductance measurement can be performed without driving the multi-phase AC motor.

[0086] Furthermore, since the response angular frequency of the current controller in the voltage application unit of the interferometric measurement group is set to a value that is sufficiently higher than the voltage command angular frequency, inductance measurement can be performed without driving multiple multiphase AC motors, and the angular frequency set value component of the interferometric measurement voltage value can be controlled to 0, thereby improving the accuracy of inductance calculation.

[0087] Furthermore, by repeatedly assigning the self-test group to each winding group in sequence, the interference inductance from one winding group to other winding groups can be calculated individually for each winding group in all winding groups. This has the effect of measuring the interference inductance of each winding group even when the interference inductance between a certain winding group and other winding groups are different.

[0088] Implementation Method 2

[0089] The inductance measuring device for the multi-phase AC motor according to Embodiment 2 will be described below. In Embodiment 2, unlike Embodiment 1, the inductance measuring device 1 applies voltage k times (k is a natural number greater than or equal to 2) while changing the effective value of the voltage command Vh_s in a manner that makes the effective value of the self-test current detection value Iuvw_s different each time. Furthermore, the same inductance calculation as in Embodiment 1 is performed for each voltage application. Since Embodiment 2 also uses the structure of the inductance measuring device 1 for the dual-phase three-phase synchronous motor 2A of Embodiment 1, the description is omitted.

[0090] Furthermore, in this embodiment 2, in Figure 5 In step ST5, when the inductor calculator 33 of the inductor calculation unit 30 calculates the γ-axis inductance Lγ_s(ε) of the self-test group and the γ-axis interference inductance Mγ_m(ε) of the interferometric group from the self-test group at the scanning phase angle ε, it also calculates the d-axis current Id_s and the q-axis current Iq_s based on the γ-axis current high-frequency component Iγh_s(ε) extracted by the fundamental component extractor 32.

[0091] For example, when the maximum value of the γ-axis inductance Lγ_s(ε) of the self-test group is used as the d-axis and the d-axis inductance Ld_s is defined, the d-axis current Id_s becomes the minimum value of the high-frequency component Iγh_s(ε) of the γ-axis current. Similarly, when the minimum value of the γ-axis inductance Lγ_s(ε) of the self-test group is used as the d-axis and the d-axis inductance Ld_s is defined, the d-axis current Id_s becomes the maximum value of the high-frequency component Iγh_s(ε) of the γ-axis current.

[0092] Furthermore, the q-axis current Iq_s is the value of the other axis. That is, when the d-axis current Id_s is the minimum value of the high-frequency component Iγh_s(ε) of the γ-axis current, the q-axis current Iq_s becomes the maximum value of the high-frequency component Iγh_s(ε) of the γ-axis current, and when the d-axis current Id_s is the maximum value of the high-frequency component Iγh_s(ε) of the γ-axis current, the q-axis current Iq_s becomes the minimum value of the high-frequency component Iγh_s(ε) of the γ-axis current.

[0093] In this way, the d-axis current Id_s(k), q-axis current Iq_s(k), and their corresponding d-axis inductance Ld_s(k), q-axis inductance Lq_s(k) of the self-test group, as well as the d-axis interference inductance Md_s(k) and q-axis interference inductance Mq_s(k) of the interferometric measurement group from the self-test group can be obtained by applying voltage multiple times (k times).

[0094] Furthermore, by applying the least squares method and other methods to derive functional relationships for multiple measurement points such as d-axis current Id_s(k) and d-axis inductance Ld_s(k), q-axis current Iq_s(k) and q-axis inductance Lq_s(k), d-axis current Id_s(k) and d-axis interference inductance Md_s(k), and q-axis current Iq_s(k) and q-axis interference inductance Mq_s(k), the variation characteristics of each inductance value due to magnetic saturation accompanying the change of each current value can be determined.

[0095] If, as in Implementation Method 1, it is known in advance that the windings of the self-test group and the interferometric measurement group have no salient polarity or are so small as to be negligible, the process of changing the scanning phase angle ε from 0 [rad] to π [rad] can be omitted. Instead, the process is performed only at any single point of the scanning phase angle ε [rad], and only L_s(k)=Ld_s(k)=Lq_s(k), I_s(k)=Id_s(k)=Iq_s(k), and M_s(k)=Md_s(k)=Mq_s(k) are calculated, thereby omitting repeated execution. Figure 5 The process of steps ST4 to ST6.

[0096] In summary, according to Embodiment 2, the same effect as Embodiment 1 is achieved. Furthermore, while varying the effective value of the voltage command Vh_s, k (k≥2) voltage applications are performed, and the d-axis current Id_s(k), q-axis current Iq_s(n) and their corresponding self-test group's d-axis inductance Ld_s(k), q-axis inductance Lq_s(k), and the interference inductance from the self-test group in the interferometric measurement group, namely the d-axis interference inductance Md_s(k) and q-axis interference inductance Mq_s(k), are determined. This provides the ability to determine the variation characteristics of each inductance value due to magnetic saturation accompanying the changes in each current value.

[0097] Implementation Method 3

[0098] Hereinafter, in Embodiment 3, the measurement object of the inductance measuring device for multiple sets of multiphase AC motors described in Embodiments 1 and 2 will be described using the accompanying drawings.

[0099] Figure 6 This is an example of a multi-phase AC motor 2, and is a schematic diagram showing the structure of a dual-phase three-phase synchronous motor. Figure 6In this dual-group three-phase synchronous motor 2A, a permanent magnet 102 is provided around the mover 101, and two stator winding groups 103A and 103B are formed in two layers radially separated from the permanent magnet 102. Power is supplied to the stator winding groups 103A and 103B from independent power converters to drive the dual-group three-phase synchronous motor 2A. Furthermore, in Figure 6 In the diagram, the cross-sections of stator winding groups 103A and 103B are shown.

[0100] When measuring the inductance of the dual-group three-phase synchronous motor 2A, for example, stator winding group 103A is used as the self-test group (first group), and stator winding group 103B is used as the interferometric measurement group (second group). Voltage is applied to stator winding group 103A from the self-test group voltage application unit 10, and voltage is applied to stator winding group 103B from the interferometric measurement group voltage application unit 20. As a result, the inductance measuring device 1 can obtain the self-inductance and mutual inductance with high accuracy without rotating the dual-group three-phase synchronous motor 2A.

[0101] Figure 7A as well as Figure 7B This is another example of a multi-phase AC motor 2, and is a schematic diagram showing the structure of a direct-acting rotary actuator 2B as one of the multi-degree-of-freedom actuators. Figure 7A In the direct-acting rotary actuator 2B, a permanent magnet 102 is provided around the mover 101, and two stator winding groups 103 and 104 are formed in two layers radially separated from the permanent magnet 102. Power is supplied to the stator winding groups 103 and 104 from independent power converters to drive the direct-acting rotary actuator 2B. Furthermore, in Figure 7A In the diagram, the cross-sections of stator winding groups 103 and 104 are shown.

[0102] Stator winding group 103 is a z-axis stator winding group that generates a traveling magnetic field in the direct z-direction of the mover 101. On the other hand, stator winding group 104 is an θ-axis stator winding group that generates a rotating magnetic field in the rotation θ-direction of the mover 101. Figure 7B This is an enlarged view of stator winding groups 103 and 104 from the side. Stator winding group 103 is configured with multiple phase windings arranged along the z-axis, and stator winding group 104 is as follows... Figure 7B The configuration shown is that multiple windings are arranged in the θ direction.

[0103] If the inductance measuring device 1 described in Embodiment 1 or 2 is applied, self-inductance and mutual inductance can be obtained with high precision without activating the direct-acting rotary actuator 2B. In this case, for example, self-inductance and mutual inductance can be obtained by setting the stator winding group 103 as the self-test group (i.e., the first group), the stator winding group 104 as the interferometric measurement group (i.e., the second group), applying voltage to the stator winding group 103 from the self-test group voltage application unit 10, applying voltage to the stator winding group 104 from the interferometric measurement group voltage application unit 20, or by the reverse setting.

[0104] As described above, the inductance measuring device 1 according to embodiment 1 or 2 above can obtain self-inductance and mutual inductance with high precision without operating the actuator with a high degree of freedom.

[0105] In addition, although Figure 6 An example of a dual-group three-phase synchronous motor 2A is shown, but if the winding groups are further stacked in the circumferential direction, it is of course possible to apply the inductance measuring device 1 to multi-group multiphase AC motors with more than 2 winding groups.

[0106] As described above, according to Embodiment 3, the same effects as Embodiments 1 and 2 are achieved.

[0107] Figure 8 This is a diagram illustrating an example of the hardware structure of the inductance measuring device 1 in embodiments 1 to 3 described above. For example... Figure 8 As shown, the inductance measuring device 1 has, for example, a processor 1000 and a storage device 1100 as a processing circuit.

[0108] The processor 1000 may include a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit), an IC, a FPGA (Field Programmable Gate Array), various logic circuits, and various signal processing circuits. Furthermore, the processor 1000 may include processors of the same or different types, each performing its respective processing task. The storage device 1100 includes RAM (Random Access Memory) configured to allow data to be read and written by the processor 1000, and ROM (Read Only Memory) configured to allow data to be read by the processor 1000. The processor 1000 executes programs input from the storage device 1100, such as the ROM.

[0109] In this invention, various exemplary implementation methods and embodiments are described. However, the various features, schemes and functions described in one or more implementation methods are not limited to specific implementation methods and can be applied to implementation methods individually or in various combinations.

[0110] Therefore, numerous variations not illustrated are contemplated within the scope of the technology disclosed in this specification. For example, these include variations of at least one structural element, additions, omissions, and extraction of at least one structural element combined with structural elements from other embodiments.

[0111] Explanation of the label

[0112] 1: Inductance measuring device; 2: Multi-phase AC motor; 2A: Dual-phase three-phase synchronous motor; 2B: Direct-acting rotary actuator; 10: Self-test voltage application unit; 11: Voltage command generation unit; 12: Power converter; 13: Current detector; 20: Interferometric measurement voltage application unit; 21: Voltage command generation unit; 22: Power converter; 23: Current detector; 24: Coordinate transformer; 25: Current controller; 26: Coordinate transformer; 30: Inductance calculation unit; 31: Coordinate transformer; 32: Fundamental component extractor; 33: Inductance calculator; 34: RMS value calculator; 101: Mover; 102: Permanent magnet; 103, 103A, 103B, 104: Stator winding group; 1000: Processor; 1100: Storage device.

Claims

1. An inductance measuring device that measures inductances of a plurality of multiphase alternating current machines each having a plurality of multiphase winding groups, wherein the inductance measuring device having a voltage application unit that applies a voltage and a current detection unit that detects a current, for each of the winding groups, and having an inductance calculation unit that calculates inductances, one of the winding groups being set as a self-measurement group, and the winding groups other than the self-measurement group being set as interference measurement groups, the voltage application unit of the self-measurement group applying a measurement voltage based on a measurement voltage command value and without driving the plurality of multiphase alternating current machines, the voltage application unit of the interference measurement groups having a current controller that applies an interference measurement voltage based on an interference measurement voltage command value that controls a current of the interference measurement groups to zero and without driving the plurality of multiphase alternating current machines, the inductance calculation unit calculating a self-inductance of the self-measurement group and a mutual inductance from the self-measurement group to the interference measurement groups based on the current detected by the current detection unit of the self-measurement group and the interference measurement voltage command value.

2. The inductance measuring device according to claim 1, wherein the measurement voltage is a multiphase alternating current voltage, and a voltage command angular frequency used to generate the measurement voltage command value is set to a value higher than a drivable angular frequency of the plurality of multiphase alternating current machines.

3. The inductance measuring device according to claim 2, wherein a response angular frequency of the current controller is set to a value higher than the voltage command angular frequency.

4. The inductance measuring device according to any one of claims 1 to 3, wherein one of the winding groups other than the self-measurement group is set as a renewed self-measurement group, and the winding groups other than the renewed self-measurement group are set as renewed interference measurement groups, the inductance calculation unit calculates a self-inductance of the renewed self-measurement group and a mutual inductance from the renewed self-measurement group to the renewed interference measurement groups.

5. The inductance measuring device according to any one of claims 1 to 4, wherein the voltage application unit of the self-measurement group changes a voltage command effective value in such a manner that an effective value of a current detected by the current detection unit possessed by the voltage application unit of the self-measurement group differs, generates different measurement voltage command values, and applies different measurement voltages to the self-measurement group based on the different measurement voltage command values, the inductance calculation unit calculates a self-inductance of the self-measurement group and a mutual inductance from the self-measurement group to the interference measurement groups for each of the different current effective values.

6. The inductance measuring device according to any one of claims 1 to 5, wherein The inductance operation unit has a fundamental component extractor that extracts a fundamental component current that is a component of the same frequency as a voltage command angular frequency used to generate the measurement voltage command value from a current detected by the self-test group current detection unit, and an effective value calculator that calculates an effective value of the interference measurement voltage command value, The inductance operation unit operates a self-inductance of the self-test group and a mutual inductance from the self-test group to the interference measurement group based on the fundamental component current, the effective value of the interference measurement voltage command value, the voltage command angular frequency, and a voltage command effective value used to generate the measurement voltage command value.

7. The inductance measurement device according to any one of claims 1 to 6, wherein The multi-group multi-phase alternating current machine that is an object of measurement of inductance is a double-group three-phase synchronous motor.

8. The inductance measurement device according to any one of claims 1 to 6, wherein The multi-group multi-phase alternating current machine that is an object of measurement of inductance is a direct-drive rotary actuator that orthogonally generates magnetic fields generated by 2 of the winding groups.

9. An inductance measurement method that measures inductance of a multi-group multi-phase alternating current machine having a plurality of multi-phase winding groups, wherein one of the plurality of winding groups is set as a self-test group, and the winding groups other than the self-test group are set as interference measurement groups, a measurement voltage based on a measurement voltage command value and not driving the multi-group multi-phase alternating current machine is applied to the self-test group, a current of the self-test group and a current of the interference measurement group are detected, an interference measurement voltage based on an interference measurement voltage command value that controls the current of the interference measurement group to 0 and not driving the multi-group multi-phase alternating current machine is applied to the interference measurement group, a self-inductance of the self-test group and a mutual inductance from the self-test group to the interference measurement group are operated based on the current detected by the self-test group current detection unit and the interference measurement voltage command value.

10. The inductance measurement method according to claim 9, wherein one of the winding groups other than the self-test group is set as an updated self-test group, and the winding groups other than the updated self-test group are set as updated interference measurement groups, a self-inductance of the updated self-test group and a mutual inductance from the updated self-test group to the updated interference measurement group are operated for the updated self-test group and the interference measurement group, the inductance of the multi-group multi-phase alternating current machine is sequentially measured with all of the winding groups being set as the self-test group.

11. The inductance measurement method according to claim 9, wherein a voltage command effective value is changed so that an effective value of a current value of the self-test group is different, different measurement voltage command values are generated, and different measurement voltages are sequentially applied to the self-test group based on the different measurement voltage command values, a self-inductance of the self-test group and a mutual inductance from the self-test group to the interference measurement group are operated for each of the different effective values of the current value.

Images