Inductive measuring device and inductive measuring method

Abstract

The inductance measuring device (10) includes: a power conversion unit (2) that applies voltage to an AC motor (11); a voltage command generation unit (1) that generates a voltage command for the power conversion unit; and an inductance calculation unit (4) that calculates the inductance of the AC motor based on a first current flowing through the AC motor when a first voltage is applied to the AC motor and a second current flowing through the AC motor when a second voltage is applied to the AC motor after the first voltage is applied. The voltage command generation unit generates the first d-axis voltage command and the first q-axis voltage command based on a first voltage command indicating the first voltage and a predetermined voltage division reference, such that there are multiple first d-axis voltage commands indicating the voltage of the d-axis of the rotating coordinate system and a first q-axis voltage command indicating the voltage of the q-axis, and in the case of a 0 voltage command, the 0 voltage command is executed before the non-0 voltage command. Based on the multiple first d-axis voltage commands and the first q-axis voltage commands generated, the power conversion unit is instructed multiple times to apply voltage to the AC motor.

Description

Technical Field

[0001] This invention relates to an inductance measuring device and a method for measuring the inductance of an AC motor. Background Technology

[0002] In the control of AC motors, information such as the inductance of the AC motor is used as control parameters. Therefore, control parameters need to be obtained before starting the control of the AC motor. Patent Document 1 discloses a control device for a rotating motor capable of measuring the inductance of the rotating motor.

[0003] The control device described in Patent Document 1 measures the inductance after repeatedly applying multiple voltage commands to make the d-axis current or q-axis current the target current.

[0004] Specifically, in the control device described in Patent Document 1, a first voltage command (measurement preparation voltage command) is repeatedly given to the voltage application unit to raise the shaft current of the rotating motor to the measurement point. Then, a second voltage command (measurement voltage command) is given to generate a small current change, and the inductance is calculated based on the amount of current change and the voltage.

[0005] Patent Document 1: Japanese Patent No. 5634620 Summary of the Invention

[0006] In the technology described in Patent Document 1, a voltage is applied to an arbitrary vector direction of the rotating coordinate system, and the inductance of each axis is measured individually by detecting the current of each of the d-axis and q-axis. However, when measuring the inductance while both the d-axis and q-axis are energized by applying voltages, the measurement accuracy of the d-axis current and q-axis current may deteriorate depending on the method of voltage application.

[0007] Here, as a comparative example, we use Figure 2 and Figure 3 The control actions that cause the measurement accuracy of d-axis and q-axis currents to deteriorate are explained. Figure 2 This diagram illustrates an example of voltage commands for the d-axis and q-axis in a proportional control operation. Figure 3 This is a graph illustrating an example of how voltage and current change over time when a proportional control action is executed. Furthermore, in the following description, the d-axis and q-axis may sometimes be collectively referred to as the dq-axis or d-axis q-axis.

[0008] When measuring inductance with both the d-axis and q-axis energized, voltage commands need to be applied simultaneously to both axes as voltage vectors. However, when the power conversion unit driving the AC motor is given multiple voltage commands to cause the shaft current to rise in stages, the number of non-zero voltage commands in the d-axis and q-axis may differ. For example, the voltage command used to boost the current of the d- and q-axis axes to the measurement point may be different. Figure 2 In the case of the voltage vector shown, such as Figure 3 As shown, regarding the d-axis current I d If two non-zero voltage commands are given, the measurement point will be reached, regarding the q-axis current I. q If four non-zero voltage commands are given, the measurement point will be reached. Therefore, as... Figure 3 As shown, a voltage is generated in the d-axis with a waiting time, and a current I is generated in the q-axis. q The actual time point at which the measurement is performed, and the d-axis current I. d The value represented by the white circle (○) becomes lower than the value of the original measurement point represented by the black circle (●). Therefore, the measured value of the d-axis current contains an error relative to the originally desired target value, which is the reason for the deterioration of the inductance measurement accuracy.

[0009] The present invention was made in view of the above circumstances, and its object is to provide an inductance measuring device capable of measuring the inductance of an AC motor with high precision.

[0010] To solve the above problems and achieve the objective, the inductance measuring device of the present invention is characterized by comprising: a power conversion unit that applies voltage to an AC motor; a voltage command generation unit that generates a voltage command for the power conversion unit; and an inductance calculation unit that calculates the inductance of the AC motor based on a first current flowing through the AC motor when a first voltage is applied to the AC motor and a second current flowing through the AC motor when a second voltage is applied to the AC motor after the first voltage is applied. The voltage command generation unit generates the first d-axis voltage command and the first q-axis voltage command, which are of equal quantity, based on the first voltage command indicating the first voltage and a predetermined voltage division reference. Furthermore, when a 0 voltage command is included, the 0 voltage command is executed before non-0 voltage commands. Based on the generated multiple first d-axis voltage commands and first q-axis voltage commands, the power conversion unit is repeatedly instructed to apply voltage to the AC motor.

[0011] The effects of the invention

[0012] The inductance measuring device of the present invention achieves the effect of measuring the inductance of AC motors with high precision. Attached Figure Description

[0013] Figure 1 This is a diagram illustrating a structural example of the inductance measuring device according to Embodiment 1.

[0014] Figure 2 This is a diagram illustrating an example of voltage commands for the d-axis and q-axis in a proportional control operation.

[0015] Figure 3 This is a diagram illustrating an example of how voltage and current change over time when a proportional control action is executed.

[0016] Figure 4 This is a diagram representing a stable inductor.

[0017] Figure 5 This is a diagram representing differential inductance.

[0018] Figure 6 This is a flowchart illustrating an example of the inductance measurement operation of the inductance measurement device according to Embodiment 1.

[0019] Figure 7 This is a diagram illustrating an example of a method for dividing a first voltage vector command executed by the voltage command generation unit of the inductance measuring device according to Embodiment 1.

[0020] Figure 8 This is a diagram illustrating an example of the operation of the inductance measuring device according to Embodiment 1, which applies voltage to an AC motor and increases the current to a first measuring point.

[0021] Figure 9 This is a diagram illustrating an example of the operation of the inductance measuring device according to Embodiment 1, which applies voltage to an AC motor and increases the current to a second measuring point.

[0022] Figure 10 This is a diagram illustrating an example of a method for dividing a first voltage vector command executed by the voltage command generation unit of the inductance measuring device according to Embodiment 2.

[0023] Figure 11 This is a diagram illustrating an example of the operation of the inductance measuring device according to Embodiment 2, which applies voltage to an AC motor and raises the current to a first measuring point.

[0024] Figure 12 This is a flowchart illustrating an example of the inductance measurement operation of the inductance measurement device according to Embodiment 4.

[0025] Figure 13 This diagram shows an example of the hardware for implementing the inductance measuring device according to embodiments 1 to 6. Detailed Implementation

[0026] The inductance measuring device and inductance measuring method according to embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0027] In the embodiments described below, the components of each phase of the three-phase AC are represented as U-phase, V-phase, and W-phase, and the two axes in the rotating coordinate system are represented as the d-axis and q-axis. The d-axis is a reference direction in the rotating coordinate system; for example, in the rotating coordinate system of a synchronous machine with excitation, it is set as the direction of its excitation, and in the rotating coordinate system of a reluctance synchronous machine without excitation, it is set as the direction of its maximum or minimum inductance, etc. These reference directions are set as θ. e Reference direction θ e It is possible to perform detection using known technologies, such as those disclosed in Japanese Patent No. 4271397.

[0028] Implementation Method 1

[0029] Figure 1 This diagram illustrates a structural example of the inductance measuring device 10 according to Embodiment 1. The inductance measuring device 10 includes a voltage command generation unit 1, a power conversion unit 2, a current detection unit 3, an inductance calculation unit 4, and a coordinate transformation unit 5. The inductance measuring device 10 measures inductance, which is used as a control parameter for an AC motor 11, such as an AC motor. Although in Figure 1 The description is omitted, but the AC motor 11 is connected to the load device. Furthermore, the hardware structure of the inductance measuring device 10 is the same as that of the power conversion device that supplies three-phase AC power to the AC motor 11 to drive the AC motor 11. The inductance measurement function of the AC motor 11 implemented by the inductance measuring device 10 can also be included in the functions of the power conversion device that drives the AC motor 11.

[0030] Voltage command generation unit 1 generates voltage commands (V) for the d-axis and q-axis of the rotating coordinate system, respectively. d * V q * ), and generate (V) by performing a rotational coordinate transformation on them. d * V q * The corresponding three-phase voltage command (V) u * V v * V w * The voltage command generation unit 1 outputs the voltage commands (V) for the d-axis and q-axis of the rotating coordinate system to the power conversion unit 2. Additionally, the voltage command generation unit 1 outputs the voltage commands (V) for the d-axis and q-axis of the rotating coordinate system to the power conversion unit 2. d * V q* The output is sent to the inductor calculation unit 4. The power conversion unit 2 generates the three-phase AC voltage indicated by the voltage command input from the voltage command generation unit 1 and applies it to the AC motor 11. The current detection unit 3 detects the current (I) flowing from the power conversion unit 2 to the AC motor 11 for each of the three phases. u I v I w The coordinate transformation unit 5 transforms the three-phase current detected by the current detection unit 3 into the d-axis current (I) of the rotating coordinate system. d ) and q-axis current (I q The output is then sent to the inductance calculation unit 4. The inductance calculation unit 4 calculates the inductance of the AC motor 11 based on the voltage commands for the d-axis and q-axis input from the voltage command generation unit 1, and the current for the d-axis and q-axis input from the coordinate transformation unit 5.

[0031] In the inductance measuring device 10, the inductance calculation unit 4 calculates the inductance of the AC motor 11 based on the measured values ​​of the current of each axis when both the d-axis and q-axis are energized. At this time, the voltage command generation unit 1 outputs multiple three-phase voltage commands corresponding to the voltage commands of the d-axis and q-axis to the power conversion unit 2, raising the current of each axis to the measurement point. In addition, when measuring the current of each axis to the measurement point, a voltage is applied to avoid deterioration in the measurement accuracy of the current.

[0032] Next, the detailed operation of the inductance measuring device 10 according to this embodiment will be explained.

[0033] Below, the inductance of the AC motor 11 measured by the inductance measuring device 10 is defined using two terms: (1) and (2). Equation (1) represents the slope of the magnetic flux and current at the origin, called the steady inductance L. Equation (2) represents the slope of the local magnetic flux change and current change, called the differential inductance L'. If these inductances are shown in a diagram, then... Figure 4 and Figure 5 As shown. Figure 4 This is a diagram representing the stable inductance L. Figure 5 This is a diagram representing the differential inductance L'.

[0034] [Mathematical Expression 1]

[0035]

[0036] [Mathematical Expression 2]

[0037]

[0038] According to equations (1) and (2), there is a relationship (3) between the stable inductance L and the differential inductance L'.

[0039] [Mathematical Expression 3]

[0040]

[0041] exist Figure 6 The flowchart shows the operation of the inductance measuring device 10 measuring the inductance. Furthermore, Figure 6 This is a flowchart illustrating an example of the inductance measurement operation of the inductance measuring device 10 according to Embodiment 1.

[0042] In the case of measuring inductance, the inductance measuring device 10 first uses a first voltage vector command V1, which indicates a first voltage, i.e., measures the voltage to be used. * Generate the first segmented voltage vector instruction V1 * [n1] (n1=1, 2, ...) (step S11). Specifically, the voltage command generation unit 1 is based on the voltage vector command V1 for measurement preparation. * Generate a voltage vector instruction V1 that is greater than or equal to a first segmentation voltage vector. * [n1] (n1=1, 2,...).

[0043] The AC motor 11 is connected to the load device, preferably capable of measuring inductance without vibration or noise. However, this requires applying voltage for an extremely short time to boost the current to the target measurement point. Therefore, in most cases, the voltage vector command V1... * This is a large voltage exceeding the range of voltages that the inductance measuring device 10 can output. Therefore, in the inductance measuring device 10, based on V1... * Generate a first segmented voltage vector instruction V1 that is greater than or equal to one. * [n1] (n1=1, 2, ...), the voltage is applied in multiple stages. As a result, the magnitude of each voltage vector becomes smaller, enabling the application of large voltages as described above. In addition, by applying voltage multiple times, the current rises to the measurement point in stages, and current measurement is performed in each stage of the rise to monitor whether excessive current is flowing, thereby protecting the inductance measuring device 10 and the AC motor 11.

[0044] The first segmented voltage vector command V1 will be generated by the voltage command generation unit 1. * Describe the details of the actions of [n1] (n1=1, 2, ...).

[0045] Next, the inductance measuring device 10 applies the first segmented voltage vector command V1. * [n1] (Step S12). Specifically, the voltage command generation unit 1 will generate a first segmented voltage vector command (V1) that is greater than or equal to one generated in step S11. * [1], V1 * [2], V1 *[3], ...) are sequentially applied to the power conversion unit 2. The power conversion unit 2 applies a voltage greater than or equal to that indicated by each of the first segmented voltage vector commands to the AC motor 11.

[0046] Specific examples are used to illustrate the details of the actions in steps S11 and S12.

[0047] The reference direction θ is set in the voltage command generation unit 1. e and the first voltage vector command V1 * First voltage vector command V1 * This is a voltage vector command used to apply the target current, i.e., the first current vector I1, to the AC motor 11. The target current is the current when the AC motor 11 outputs torque to the load device. This first voltage vector command V1 * For example, before the inductance measuring device 10 starts the inductance measurement operation, via... Figure 1 The UI (User Interface) is omitted from the description and is set by the user.

[0048] In the first voltage vector command V1 * Size is represented by |V1 * | indicates that the direction is relative to the reference direction θ e First voltage vector command V1 * The phase is represented by θ v1 * In the case of representation, such as Figure 7 As shown, the voltage command generation unit 1 generates the voltage command according to an arbitrary voltage division reference V. st The first voltage vector command V1 * Divide into sizes less than or equal to V st And multiple first segmented voltage vector commands V1 with the same phase * [n1] (n1 = 1, 2, ...). Furthermore, Figure 7 This refers to the first voltage vector command V1 executed by the voltage command generation unit 1 of the inductance measuring device 10 according to Embodiment 1. * A diagram illustrating an example of a segmentation method. In Figure 7 θ v Equivalent to the first voltage vector command V1 * phase θ v1 * That is, θ v =θ v1 * The voltage segmentation reference V used in this embodiment st Set as the first voltage division reference.

[0049] Here, the voltage division reference V stThe voltage can be set within the range that the inductance measuring device 10 can output. For example, the voltage division reference V can be set based on the rated voltage of the power conversion unit 2 and the rated voltage of the AC motor 11. st That's sufficient. Furthermore, the rated voltage mentioned here takes into account the wiring of the power conversion unit 2 and the AC motor 11. If the rated voltage is specified by the effective value of the phase voltage, then the effective value of the phase voltage = the magnitude of the voltage vector × 1 / √3. Therefore, √3 × rated voltage is set to V. st That's fine. If the rated voltage is specified by the effective value of the line-to-line voltage, then the effective value of the line-to-line voltage equals the magnitude of the voltage vector; therefore, the rated voltage is set to V. st That's all.

[0050] In the first voltage vector command V1, which is equivalent to the first voltage command, * In the segmentation operation, firstly, the voltage command generation unit 1 determines the first segmentation voltage vector command V1 to be generated. * [n1] represents their respective sizes. If |V1 * | Divide by V st The quotient and remainder obtained are denoted as k1 (k1: an integer) and V, respectively. 1k , will | V1 * Let the number of partitions of | be n1, then |V1 * | = k1 × V st +V 1k Therefore, n1 = k1 + 1. First segmented voltage vector command V1 * Size of [n1] | V1 * | [n1] is represented by the following formula (4).

[0051] [Mathematical Expression 4]

[0052]

[0053] Next, the voltage command generation unit 1 uses the first voltage vector command V1 * phase θ v1 * V1 * [n1] is separated into d-axis and q-axis components, and multiple d-axis voltage commands V are obtained. 1d * [n1] = |V1 * | [n1] × cosθ v1 * and q-axis voltage command V 1q * [n1] = |V1 * | [n1] × sinθ v1 *By dividing the data in the manner described above, the number of voltage commands for each of the d and q axes is n1, and all voltage commands are non-zero.

[0054] Voltage command generation unit 1 generates voltage commands V for the segmented d-axis. 1d * [n1] and q-axis voltage command V 1q * [n1], based on the reference direction θ e Perform dq-three-phase coordinate transformation to generate three-phase voltage command V u * V v * and V w * Then, the voltage command generation unit 1 generates the three-phase voltage command V. u * V v * and V w * Output to power conversion unit 2.

[0055] Power conversion unit 2 follows the three-phase voltage command V u * V v * and V w * , the voltage vector V1 * [n1] is applied to the AC motor 11.

[0056] As described above, the inductance measuring device 10 sends a first voltage vector command V1. * The d-axis voltage command V is generated by segmentation. 1d * [n1] and q-axis voltage command V 1q * [n1], repeatedly executes the voltage command for the dq axis, thereby applying voltage to the AC motor 11. As a result, the d-axis current I... 1d and q-axis current I 1q like Figure 8 The change shown is raised to the measurement point. Furthermore, Figure 8 This is a diagram illustrating an example of the operation of the inductance measuring device 10 according to Embodiment 1, which applies voltage to the AC motor 11 and raises the current to the first measuring point. Figure 7 and Figure 8 The inductance measuring device 10 shows the first voltage vector command V1. * An example of a scenario where the execution is divided into four parts.

[0057] Return to Figure 6Next, the inductance measuring device 10 detects the first current vector I1 (step S13). Specifically, the current detection unit 3 detects the first current vector I1. The first current vector I1 is the result of executing the first voltage vector command V1. * All d-axis voltage commands V obtained by segmentation 1d * [n1] and q-axis voltage command V 1q * [n1], the current vector at the time point for which the voltage to be applied to the AC motor 11 is measured is completed.

[0058] Next, the inductance measuring device 10 is based on the second voltage vector command V2, which indicates the second voltage, i.e., the voltage to be measured. * Generate second segmented voltage vector instruction V2 * [n2] (n2=1, 2, ...) (step S14), apply the second segmented voltage vector command V2 * [n2] (Step S15). Then, the inductance measuring device 10 detects the second current vector I2 (Step S16). Steps S14 to S16 are the same as steps S11 to S13. (The first voltage vector command V1 is also mentioned.) * Similarly, the second voltage vector command V2 * It is pre-set.

[0059] Here, regarding the second voltage vector command V2 * As long as voltage can be applied to flow through the first voltage vector command V1 * The current I1 applied at the completion time point is the change in current ΔI after the change in inductance is used for inductance calculation; therefore, its magnitude is |V2|. * | Can be configured arbitrarily. | V2 * | Can be set to be less than or equal to the voltage divider reference V st The value is achieved by applying a voltage, but due to the large inductance of the AC motor 11, applying V... st When a voltage does not cause a sufficient change in current, a voltage exceeding V is specified. st The value, and the first voltage vector command V1 * The same conditions are used to divide the data and generate multiple second-divided voltage vector commands V2. * [n2]. Furthermore, when segmentation is not required, the voltage command generation unit 1 will generate the second voltage vector command V2. * Set as V2 * [1]

[0060] exist Figure 9 The diagram shows the second voltage vector command V2, which is equivalent to the second voltage command. *Example in the case of being divided into two. Figure 9 This is a diagram showing an example of the operation in which the inductance measurement device 10 according to Embodiment 1 applies a voltage to the AC motor 11 to increase the current to the second measurement point. In steps S14 to S16, as Figure 9 shown, from the state where the first current vector I1 (I * 、I 1d 、I 1q )flows after the first voltage vector command V1 is applied, it further changes to the state where the second current vector I2 (I 2d 、I 2q )flows, and a current change ΔI = I2 - I1 occurs.

[0061] After the inductance measurement device 10 detects the second current vector I2 in step S16, it calculates the inductance of the AC motor 11 (step S17). Specifically, the inductance calculation unit 4 calculates the inductance based on the second voltage vector command V2 * and the current change ΔI. The calculated inductance is stored, for example, in the storage unit whose description is omitted in Figure 1 , and can be viewed when necessary, such as when driving the AC motor 11. The inductance measurement device 10 can also display the operation result of the inductance on the display device and notify it to the outside. The details of the inductance calculation process executed by the inductance calculation unit 4 will be described later.

[0062] In the case of voltage application described in this embodiment, the number of divisions of the voltage vector commands for the d-axis and q-axis is the same. Therefore, as Figure 7 、 Figure 8 and Figure 9 shown, non-zero voltages are applied to the d-axis and q-axis the same number of times, and at the time point when the voltage application is completed, the d-axis and q-axis can reach the target current simultaneously, and it is possible to prevent the current of one axis from decreasing after reaching the target current.

[0063] In addition, by using the d-axis voltage command V 1d * [n1]and the q-axis voltage command V 1q * [n1], the currents reached by each voltage application are respectively low values, and the inductance is a large value, so the time constant becomes large. As a result, the current decrease from the completion of each voltage application to the next voltage application becomes gentle, and the current can be appropriately increased by each voltage application.

[0064] Moreover, since the 0-voltage command is not included in the n1 voltage applications, it is also possible to specify the middle of the n1 voltage applications as the measurement point. If an integer m1 where 1 < m1 < n1 is used to represent the intermediate voltage command as V1 * [m1], then V1* [m1] is regarded as the first voltage command, and V1 is... * [m1+1] is treated as the second voltage command and inductance calculation is performed. Next, V1 * [m1+1] is regarded as the first voltage command, and V1 is... * [m1+2] is treated as the second voltage command and inductance calculation is performed until V1. * The operation is repeated until the application is complete. As a result, the following effect is obtained: not only can the inductance obtained based on the current vector I1 at a single point be measured, but the inductance obtained based on the current vector along the route up to I1 can also be measured simultaneously.

[0065] Next, the details of the inductor calculation process performed by the inductor calculation unit 4 will be explained.

[0066] The inductance calculation unit 4 calculates the inductance on the dq axis. If the voltage of one axis of the dq axis is set as v, the current is set as i, the winding resistance is set as R, and the armature linkage flux is set as Φ, then ignoring the terms related to the rotational speed, the voltage equations of the dq axis when the AC motor 11 is not rotating become equations (5) and (6).

[0067] [Mathematical Expression 5]

[0068]

[0069] [Mathematical Expression 6]

[0070]

[0071] According to equations (5) and (6), the change in magnetic flux dΦ is dΦ = (v - Ri)dt. Furthermore, if the change in d-axis current di... d The resulting change in q-axis magnetic flux is dΦ q / di d and the change in q-axis current di q The resulting d-axis magnetic flux change, i.e., dΦ d / di q The change in magnetic flux caused by the interference between the d and q axes is much smaller than the change in magnetic flux caused by the change in current of each of the d and q axes, and can be ignored. Therefore, in conjunction with the above equation (2), the differential inductance L' can be calculated as shown in equations (7) and (8).

[0072] [Mathematical Expression 7]

[0073]

[0074] [Mathematical Expression 8]

[0075]

[0076] When the inductance of the AC motor 11 is calculated using the voltage applied by the inductance measuring device 10 according to this embodiment, if one control processing cycle is set to t... s Then, by voltage vector command V2 * The magnetic flux change ΔΦ generated by [n2](n2=1、2、…) is shown in Equation (9) and Equation (10).

[0077] [Mathematical Expression 9]

[0078]

[0079] [Mathematical Expression 10]

[0080]

[0081] Here, in particular, in the measurement of inductance when the current I1 is increased to a high current, the voltage of the resistance voltage drop of RI1 becomes a relatively small value compared to V2. Therefore, equations (9) and (10) can also be approximated by equations (11) to (16) as shown below.

[0082] If the voltage drop across each resistor is omitted when each voltage vector command is applied, and only the voltage drop across the resistor when the last voltage vector command is applied is considered, then the calculation can also be performed based on equations (11) and (12), which are equivalent to the case of applying all voltage vector commands before the segmentation through a single voltage application.

[0083] [Mathematical Expression 11]

[0084]

[0085] [Mathematical Expression 12]

[0086]

[0087] Among them, V 2d * and V 2q * For the dq axis voltage command before splitting, I 1d [n2] and I 1q [n2] is the current when the last voltage vector command is applied.

[0088] Alternatively, the calculation can be performed as shown in equations (13) and (14) with all resistance voltage drops omitted.

[0089] [Mathematical Expression 13]

[0090]

[0091] [Mathematical Expression 14]

[0092]

[0093] Equations (13) and (14) are equivalent to the case where all voltage vector command values ​​before the split are applied by applying a single voltage, and therefore can also be calculated as shown in equations (15) and (16).

[0094] [Mathematical Expression 15]

[0095]

[0096] [Mathematical Expression 16]

[0097]

[0098] According to the calculation formulas (11) to (16), the number of current measurement points can be reduced.

[0099] In addition, by calculating the change in magnetic flux and the change in current ΔI between any of the formulas (9) to (16), the differential inductance L' can be calculated as in formulas (17) and (18).

[0100] [Mathematical Expression 17]

[0101]

[0102] [Mathematical Expression 18]

[0103]

[0104] Furthermore, due to the existence of equation (3), the stable inductance L can be obtained from the measurement result of the differential inductance L'. Various methods can be conceived for practical calculation, but as a method with a light computational load, the method of defining an approximate function of L(I) and expressing L(I) through the formula of L'(I) is given. For example, if L(I) is approximated by a linear function related to the current, it can be expressed as L(I) = aI + b. Therefore, according to equation (3), it becomes L'(I) = a·I + (aI + b) = 2aI + b, and L(I) is a function with the same intercept and a slope of 1 / 2 relative to L'(I).

[0105] The first-order function was used as an example to illustrate the approximation function, but calculations can also be performed using arbitrary functions such as higher-order functions or logarithmic functions.

[0106] If there are measurement results for each L'(I1) corresponding to multiple I1, then L'(I) as a function of current can be obtained as an approximate function using methods such as the least squares method.

[0107] Regarding the measurement of multiple L'(I1), for example, preparing multiple |V1 * |, used with multiple | V1 * | Corresponding to multiple first voltage vector commands V1 * According to Implementation Method 1, L' corresponding to multiple I1 can be measured.

[0108] Alternatively, as described above, in the inductance measurement performed by the inductance measurement device 10 according to this embodiment, the n1th voltage application does not include a 0 voltage instruction, so the midpoint of the n1th voltage application can also be defined as the measurement point. Therefore, if not only the inductance of a point obtained based on I1 is measured, but also the inductance of each current up to I1 is measured simultaneously, multiple L'(I) can be obtained.

[0109] Furthermore, according to the inductance calculation method of the inductance measuring device 10 according to this embodiment, the application time t of each voltage vector command can be calculated. s The time is set to an extremely short duration, thus enabling inductance measurement while minimizing the vibration and noise of the AC motor 11.

[0110] As described above, the inductance measuring device 10 according to this embodiment is based on a predetermined voltage division reference V. st The first voltage vector command V1 will be given to indicate the voltage to be measured. * The first segmented voltage vector command V1 is generated by segmentation. * [n1] is further separated into d-axis and q-axis components to generate voltage commands for each axis. Thus, the number of voltage commands for the d-axis is the same as the number of voltage commands for the q-axis, preventing a decrease in inductance measurement accuracy caused by a current measurement value for one axis being lower than its original value.

[0111] Implementation Method 2

[0112] Next, Embodiment 2 will be described. The structure of the inductance measuring device involved in Embodiment 2 is the same as that in Embodiment 1 (see [reference]). Figure 1 The inductance measurement process differs from that in Embodiment 1. The differences from Embodiment 1 will be described in this embodiment.

[0113] The difference between the inductance measuring device 10 in Embodiment 2 and Embodiment 1 lies in the first segmented voltage vector command V1 described in Embodiment 1. * The generation process of [n1] ( Figure 6 Step S11), Second Segmented Voltage Vector Command V2 * The generation process of [n2] ( Figure 6 Step S14). First segmented voltage vector command V1 *[n1] generation and second segmentation voltage vector command V2 * The generation of [n2] is performed using the same operation. Therefore, in this embodiment, the first segmented voltage vector command V1 is generated. * An example of the processing of [n1] will be used to illustrate the generation of the second segmented voltage vector instruction V2. * The treatment of [n2] is omitted.

[0114] Voltage command generation unit 1 generates the first segmented voltage vector command V1 * In the case of [n1], firstly, the voltage vector command V1 is... * Separate the components into d-axis and q-axis components, and calculate the d-axis voltage command V. 1d * and q-axis voltage command V 1q * .

[0115] Next, the voltage command generation unit 1 divides the voltage commands for each axis using the same process as in Embodiment 1. Specifically, the voltage command generation unit 1 divides the voltage commands for each axis according to the voltage division reference V common to the d-axis and q-axis. stdq The voltage command V for the d-axis is respectively applied. 1d * and q-axis voltage command V 1q * Perform segmentation and calculate multiple first d-axis segmentation voltage commands V. 1d * [n] 1d ] (n 1d =1, 2, ...) and multiple first q-axis segmented voltage commands V 1q * [n] 1q ] (n 1q =1, 2, ...). Furthermore, the voltage segmentation reference V used in this embodiment... stdq Set as the second voltage division reference.

[0116] Here, the voltage division reference V stdq The voltage can be set within the range of the dq-axis voltage that the inductance measuring device 10 can output. For example, it can be set to 1 / √2 of the rated voltage of the power conversion unit 2 and 1 / √2 of the rated voltage of the AC motor 11. By setting it in this way, even if the divided dq-axis voltages take the maximum value V, the voltage can be controlled to be within the range of the rated voltage of the power conversion unit 2 and the rated voltage of the AC motor 11. stdq The magnitude of the synthesized voltage vector will not exceed the rated voltage. Furthermore, the rated voltage referred to here, as in Embodiment 1, includes the wiring of the power conversion unit 2 and the AC motor 11.

[0117] If the d-axis voltage command V is... 1d *Size | V 1d * | Divide by V stdq Let the quotient and remainder be k respectively. 1d (k) 1d (integer) and V 1kd Then the first d-axis segmented voltage command V 1d * [n] 1d [This is represented by the following formula (19).] 1d =k 1d +1.

[0118] [Mathematical Expression 19]

[0119]

[0120] Additionally, if the q-axis voltage command V is... 1q * Size | V 1q * | Divide by V stdq Let the quotient and remainder be k respectively. 1q (k) 1q (integer) and V 1kq Then the first q-axis segmented voltage command V 1q * [n] 1q [This is represented by the following formula (20).] 1q =k 1q +1.

[0121] [Mathematical Expression 20]

[0122]

[0123] Next, voltage command generation unit 1 pairs n 1d and n 1q Comparison. Here, n 1d <n 1q Let's take the case of [example] as an example to illustrate.

[0124] In n 1d <n 1q In this case, the first d-axis segmentation voltage command V 1d * [n] 1d [and the first q-axis split voltage command V] 1q * [n] 1q Since the number is insufficient, the voltage command generation unit 1 adds an insufficient amount of n. 1q -n 1d The number is increased to n by a zero voltage command. 1qSpecifically, the voltage command generation unit 1 adds a 0 voltage command to the first half of the voltage vector command on the d-axis, generating a new first d-axis segmented voltage command V as shown in equation (21). 1dd * [n] 1q ] (n 1q =1, 2, ...).

[0125] [Mathematical Expression 21]

[0126]

[0127] Here, n 1d <n 1q The case of n was used as an example for illustration, but 1d >n 1q In the case of V 1q * [n] 1q Perform the same processing and append a 0 voltage command to generate a new q-axis voltage command V. 1qq * [n] 1d ] (n 1d =1, 2, ...). Additionally, in n 1d =n 1q In the case of voltage command generation unit 1, the voltage command generation unit 1 does not perform the processing of adding a 0 voltage command.

[0128] Based on the use of d-axis segmented voltage command V 1dd * [n] 1q ] and q-axis split voltage command V 1q * [n] 1q The voltage applied, such as Figure 10 and Figure 11 As shown, in the d-axis, an insufficient number of 0 voltage commands (V) are initially applied. 1dd * [1], V 1dd * [2]), then, according to the equivalent of V 1d * [n] 1d V 1dd * [n] 1q A voltage is applied. Therefore, the timing of voltage application completion between the d and q axes is consistent, and the d and q axes simultaneously reach the target current at the point where voltage application is completed. Therefore, similar to Embodiment 1, it is possible to prevent a decrease in inductance measurement accuracy caused by a current measurement value of one axis being lower than its original value.

[0129] Implementation Method 3

[0130] Next, Embodiment 3 will be described. The structure of the inductance measuring device involved in Embodiment 3 is the same as that in Embodiment 1 (see [reference]). Figure 1 In this embodiment, the parts that differ from those in Embodiment 1 will be described.

[0131] The voltage command generation unit 1 involved in Embodiment 3 is the same as that described in Embodiment 1. Figure 6 Before the action shown in the flowchart, the target current value |I1| desired to be achieved based on the execution of the first voltage vector command is related to the magnitude of the first voltage vector command |V1. * | Perform calculations.

[0132] Voltage command generation unit 1 determines the magnitude of the first voltage vector command |V1 * In the case of performing the calculation, firstly, the effective value Φ of the linkage magnetic flux formed by the inductor. r Perform the calculation. Here, if the rated voltage of AC motor 11 is set to V... r [Vrms], set the rated current to I r [Arms], set the excitation to Φ f [Wb], Set the rated frequency to f r [Hz] is considered as the rated current flowing through the inductor when a terminal voltage equivalent to the rated voltage is applied during rated operation, and the inductor drives at the rated frequency. The effective value Φ of the linkage magnetic flux formed by the inductor is... r It can be calculated in the manner of equation (22).

[0133] [Mathematical Expression 22]

[0134]

[0135] In cases such as reluctance AC motors without excitation, Φ is used. f =0 and can be obtained by using equation (22). The voltage command generation unit 1 defines the inductance calculated as in equation (23) as the rated inductance Lr based on equation (22).

[0136] [Mathematical Expression 23]

[0137]

[0138] Then, the voltage command generation unit 1 uses the rated inductance Lr and the target current value |I1| to determine the magnitude |V1 of the first voltage vector command as in equation (24). * | Perform calculations.

[0139] [Mathematical Expression 24]

[0140]

[0141] Voltage command generation unit 1 determines the magnitude of the first voltage vector command |V1 * | After performing the calculation, use | V1 * | Perform the inductance measurement as described in Implementation Method 1 ( Figure 6 (Steps S11 to S17 are shown).

[0142] As described above, before starting the inductance measurement, the magnitude of the first voltage vector command |V1 is determined according to equation (24). * By performing calculations, a rough estimate of the voltage vector command required for each current can be obtained when the inductance is unknown, thus reducing the first voltage vector command V1 used to achieve the target current I1. * Adjusting the working hours. Additionally, it prevents excessive current from flowing through the device, which could damage it.

[0143] Furthermore, the magnitude of the aforementioned first voltage vector command |V1 * The calculation of | can also be performed outside the voltage command generation unit 1. For example, it can be configured such that a separate voltage command calculation unit is provided, and the voltage command calculation unit calculates the magnitude of the first voltage vector command |V1. * | Perform calculations and output to voltage command generation unit 1.

[0144] Additionally, the size of the first voltage vector command |V1 * After the calculation, the inductance is measured using the method described in Embodiment 1, but the inductance can also be measured using the method described in Embodiment 2.

[0145] Implementation Method 4

[0146] Next, Embodiment 4 will be described. The structure of the inductance measuring device involved in Embodiment 4 is the same as that in Embodiment 1 (see [reference]). Figure 1 In this embodiment, the parts that differ from those in Embodiment 1 will be described.

[0147] Figure 12 This is a flowchart illustrating an example of the inductance measurement operation of the inductance measuring device 10 according to Embodiment 4.

[0148] like Figure 12 As shown, the inductance measuring device 10 according to Embodiment 4 first applies a fixed voltage to the d-axis (step S21). Specifically, the voltage command generation unit 1 generates a voltage command instructing the application of a fixed voltage to the d-axis and outputs it to the power conversion unit 2. The power conversion unit 2 applies a DC voltage as a fixed voltage in the d-axis direction at sufficiently long time intervals according to the voltage command from the voltage command generation unit 1.

[0149] Next, the inductance measuring device 10 performs a freewheeling operation on the current of the AC motor 11 (step S22). Specifically, the gate voltage of the power module in the power conversion unit 2 is cut off, and the current flowing through the AC motor 11 is set to 0.

[0150] Next, the inductance measuring device 10 performs the inductance measurement operation of the AC motor 11 (step S23). In this step S23, the inductance is measured using the method described in Embodiment 1. Figure 6 The inductance of the AC motor 11 is measured using the method shown in steps S11 to S17. Alternatively, the inductance can also be measured using the method described in Embodiment 2.

[0151] Next, in the same manner as in step S22, the inductance measuring device 10 performs a freewheeling operation on the current of the AC motor 11, setting the current flowing through the AC motor 11 to 0 (step S24). This freewheeling operation can immediately set the current of the AC motor 11 to 0, further suppressing the vibration and noise of the drive unit of the AC motor 11.

[0152] Next, the inductance measuring device 10 applies a reverse voltage command (step S25). Specifically, the voltage command generation unit 1 generates a voltage vector command indicating a voltage opposite to the inductance sensing timing and outputs it to the power conversion unit 2, which applies the indicated voltage to the AC motor 11. In this step S25, the voltage vector command V output by the voltage command generation unit 1 is... inv * For V inv * =-V1 * -V2 * This process generates a driving force that is opposite to the timing of the inductive sensing, even when the current is set to 0 through the freewheeling operation, which is still insufficient to suppress shaft vibration and noise. This further suppresses vibration and noise.

[0153] Next, the inductance measuring device 10 performs the same freewheeling operation as in steps S22 and S24 (step S26).

[0154] According to the above embodiment 4, compared with embodiments 1 to 3, the vibration and noise of the AC motor 11 can be further suppressed, and the inductance measurement can be performed more accurately.

[0155] Alternatively, appropriate selections can be made based on the condition of the AC motor 11 and the device connected to the AC motor 11. Figure 12The processes shown are those other than step S23. For example, if it is known that the drive unit of the AC motor 11 has been fixed before the measurement begins, steps S21 and S22 can be omitted. In cases where the AC motor 11 is difficult to drive, for example, if it is a rotary motor, steps S24 to S26 can be omitted if the rotation axis inertia is large, and if it is a linear motor, steps S24 to S26 can be omitted if the mover mass is large.

[0156] Implementation Method 5

[0157] Next, Embodiment 5 will be described. The structure of the inductance measuring device involved in Embodiment 5 is the same as that in Embodiment 1 (see [reference]). Figure 1 In this embodiment, the parts that differ from those in Embodiment 1 will be described.

[0158] In Embodiment 5, the case where, with both the d-axis and q-axis energized using any of the methods described in Embodiments 1-4, only one of the d-axis inductance and q-axis inductance is measured is explained. Compared to Embodiments 1-4, Embodiment 5 uses the second voltage vector command V2... * phase θ v2 * The settings are different.

[0159] The inductance measuring device 10 according to Embodiment 5 is set to θ when only the d-axis inductance is measured. v2 * =0 [deg], set to θ when only measuring q-axis inductance. v2 * =90 [deg]. That is, the current change is generated only in the d-axis direction and only in the q-axis direction to measure the d-axis inductance or q-axis inductance.

[0160] When deriving equations (5) and (6) above, the change in d-axis current di d The resulting change in q-axis magnetic flux is dΦ q / di d and the change in q-axis current di q The resulting d-axis magnetic flux change, i.e., dΦ d / di q The change in magnetic flux caused by the interference between the d and q axes is significantly smaller than the change in magnetic flux caused by the change in current along each of the d and q axes, and can be ignored. However, in cases where more accurate inductance measurements are desired for comparison with results from magnetic field analysis, generating current changes only along the d axis and only along the q axis, thus eliminating the influence of the change in magnetic flux caused by the interference between the d and q axes, allows for more accurate inductance calculations.

[0161] Implementation Method 6

[0162] Next, Embodiment 6 will be described. The structure of the inductance measuring device involved in Embodiment 6 is the same as that in Embodiment 1 (see [reference]). Figure 1 In this embodiment, the parts that differ from those in Embodiment 1 will be described.

[0163] The inductance measuring device 10 according to Embodiment 6 uses the first voltage vector command V1 generated by the voltage command generation unit 1. * Set the size to |V1 * | , sets multiple values, such as current vectors of various magnitudes ranging from 0 to the rated current of AC motor 11, as |V1 * Additionally, the first voltage vector command V1 * Let the phase be θ v1 * Multiple phases in the range of 0 to 90 degrees are set as θ. v1 * Regarding these | V1 * | and θ v1 * Inductance was measured for all combinations.

[0164] That is, the voltage command generation unit 1, within the range specified based on the rated current of the AC motor 11, generates a voltage command for the magnitude |V1. * | and phase θ v1 * Make changes while repeatedly generating the first voltage vector command V1. * The first segmented voltage vector command is generated and output to the power conversion unit 2 according to the process described in Embodiment 1. The voltage command generation unit 1 then generates the second voltage vector command V2. * The magnitude and phase are fixed. The inductance calculation unit 4 processes the first voltage vector command V1 generated by the voltage command generation unit 1. * Each of them is calculated using the method described in Implementation 1.

[0165] Then, the inductor operation unit 4 will correspond to all I 1d and I 1q The inductance measurement results are tabulated to create tabular data on inductance.

[0166] The first voltage vector command V1 * Set the size to |V1 * | Set multiple values, such as a current vector of various magnitudes, ranging from 0 to the rated current of the AC motor 11, as the phase θ. v1 *Multiple phases are defined within a range of 0 to 90 degrees, thus multiple first voltage vector commands V1 are derived from all their combinations. * This includes the voltage vectors that are desirable for driving the AC motor 11. According to this embodiment 6, tabular data covering the inductances that are desirable for driving the AC motor 11 can be obtained.

[0167] In addition, the voltage command generation unit 1 can also generate the first segmented voltage vector command and the second segmented voltage vector command using the process described in Embodiment 2.

[0168] Next, the hardware for implementing the inductance measuring device 10 described in embodiments 1 to 6 will be explained.

[0169] The power conversion unit 2 of the inductance measuring device 10 is implemented, for example, by an inverter. The current detection unit 3 of the inductance measuring device 10 is implemented, for example, by a current sensor.

[0170] Furthermore, the voltage command generation unit 1, the inductance calculation unit 4, and the coordinate transformation unit 5 of the inductance measuring device 10 are, for example, composed of... Figure 13 The processor 91 and memory 92 shown are implemented as described. Furthermore... Figure 13 This diagram shows an example of the hardware implementing the inductance measuring device 10 according to embodiments 1 to 6.

[0171] Examples of processor 91 are CPU (Central Processing Unit, also known as central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, DSP (Digital Signal Processor)) or system LSI (Large Scale Integration). Examples of memory 92 are non-volatile or volatile semiconductor memories such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, and disks.

[0172] The voltage command generation unit 1, inductance calculation unit 4, and coordinate transformation unit 5 of the inductance measuring device 10 described in each embodiment are implemented by the processor 91 executing a program for implementing each of the above units. The program for implementing the voltage command generation unit 1, inductance calculation unit 4, and coordinate transformation unit 5 of the inductance measuring device 10 is pre-stored in the memory 92. The processor 91 reads the program from the memory 92 and executes it, thereby operating the voltage command generation unit 1, inductance calculation unit 4, and coordinate transformation unit 5 of the inductance measuring device 10.

[0173] The voltage command generation unit 1, inductance calculation unit 4, and coordinate transformation unit 5 of the inductance measuring device 10 have been described using a general-purpose processor 91 and memory 92. However, these units can also be implemented using dedicated processing circuits. Examples of dedicated processing circuits include single circuits, composite circuits, programmable processors, parallel-programmable processors, ASICs (Application Specific Integrated Circuits), FPGAs (Field Programmable Gate Arrays), etc. It is also possible to combine two or more of the above-described processing circuits to implement the various parts of the inductance measuring device. Furthermore, it is also possible to... Figure 13 The processor 91, memory 92, and dedicated processing circuitry shown combine to implement the voltage command generation unit 1, inductance calculation unit 4, and coordinate transformation unit 5 of the inductance measurement device 10. For example, the voltage command generation unit 1 and inductance calculation unit 4 can be implemented using the processor 91 and memory 92, and the coordinate transformation unit 5 can be implemented using dedicated processing circuitry.

[0174] The structure shown in the above embodiments is an example and can be combined with other known technologies. The embodiments can also be combined with each other. Without departing from the main idea, a part of the structure can be omitted or changed.

[0175] Explanation of the label

[0176] 1 Voltage command generation unit, 2 Power conversion unit, 3 Current detection unit, 4 Inductance calculation unit, 5 Coordinate transformation unit, 10 Inductance measurement device, 11 AC motor.

Claims

1. An inductance measuring device, characterized in that, have: The power conversion unit applies voltage to the AC motor; A voltage command generation unit generates a voltage command for the power conversion unit; and The inductance calculation unit calculates the inductance of the AC motor based on a first current flowing through the AC motor when a first voltage is applied to the AC motor and a second current flowing through the AC motor when a second voltage is applied to the AC motor after the first voltage is applied. The voltage command generation unit generates the first d-axis voltage command and the first q-axis voltage command based on the first voltage command indicating the first voltage and the defined voltage division reference. The first d-axis voltage command and the first q-axis voltage command are generated in a plurality of equal quantities, and when a 0 voltage command is included, the 0 voltage command is executed before the non-0 voltage command. Based on the generated plurality of first d-axis voltage commands and first q-axis voltage commands, the power conversion unit repeatedly instructs the voltage to be applied to the AC motor.

2. The inductance measuring device according to claim 1, characterized in that, The voltage segmentation reference is either the voltage segmentation reference on the same phase as the first voltage command, i.e., the first voltage segmentation reference, or the voltage segmentation reference on the d-axis and q-axis of the rotating coordinate system, i.e., the second voltage segmentation reference.

3. The inductance measuring device according to claim 2, characterized in that, The voltage command generation unit divides the first voltage command into a plurality of first segmented voltage commands having the same phase as the first voltage command based on the first voltage segmentation reference, and separates each of the plurality of first segmented voltage commands into a d-axis component and a q-axis component to generate a plurality of first d-axis voltage commands and first q-axis voltage commands.

4. The inductance measuring device according to claim 2 or 3, characterized in that, The voltage command generation unit generates multiple, equal-number second d-axis voltage commands indicating the voltage of the d-axis and second q-axis voltage commands indicating the voltage of the q-axis based on the first voltage division reference and the second voltage command indicating the second voltage. Furthermore, based on the generated multiple second d-axis voltage commands and second q-axis voltage commands, the power conversion unit repeatedly instructs the power conversion unit to apply voltage to the AC motor.

5. The inductance measuring device according to claim 4, characterized in that, The voltage command generation unit divides the second voltage command into a plurality of second segmented voltage commands having the same phase as the second voltage command based on the first voltage segmentation reference, and separates each of the plurality of second segmented voltage commands into a d-axis component and a q-axis component to generate a plurality of second d-axis voltage commands and second q-axis voltage commands.

6. The inductance measuring device according to any one of claims 2 to 5, characterized in that, The first voltage division reference is set as the rated voltage of the power converter constituting the power conversion unit.

7. The inductance measuring device according to any one of claims 2 to 5, characterized in that, Set the first voltage division reference to the rated voltage of the AC motor.

8. The inductance measuring device according to claim 2, characterized in that, The voltage command generation unit separates the first voltage command into a d-axis component and a q-axis component. Based on the second voltage segmentation reference, it segments each of the d-axis component and the q-axis component of the first voltage command. If the number of d-axis components of the segmented first voltage command is different from the number of q-axis components, it adds a 0 voltage command to the side with the smaller number, thereby generating the same number of first d-axis voltage commands and first q-axis voltage commands.

9. The inductance measuring device according to claim 8, characterized in that, The voltage command generation unit generates multiple, equal-number second d-axis voltage commands indicating the voltage of the d-axis and second q-axis voltage commands indicating the voltage of the q-axis based on the second voltage division reference and the second voltage command indicating the second voltage. Furthermore, based on the generated multiple second d-axis voltage commands and second q-axis voltage commands, the power conversion unit repeatedly instructs the power conversion unit to apply voltage to the AC motor.

10. The inductance measuring device according to claim 9, characterized in that, The voltage command generation unit separates the second voltage command into a d-axis component and a q-axis component. Based on the second voltage segmentation reference, it segments each of the d-axis component and the q-axis component of the second voltage command. If the number of d-axis components of the segmented second voltage command is different from the number of q-axis components, it adds a 0 voltage command to the side with the smaller number, generating the same number of second d-axis voltage commands and second q-axis voltage commands. Furthermore, based on the generated multiple second d-axis voltage commands and second q-axis voltage commands, it repeatedly instructs the power conversion unit to apply voltage to the AC motor.

11. The inductance measuring device according to claim 8 or 10, characterized in that, The voltage command generation unit appends the 0 voltage command in such a way that the 0 voltage command is executed first.

12. The inductance measuring device according to any one of claims 8 to 11, characterized in that, The second voltage division reference is set to 1 / √2 times the rated voltage of the power converter constituting the power conversion section.

13. The inductance measuring device according to any one of claims 8 to 11, characterized in that, The second voltage division benchmark is set to 1 / √2 times the rated voltage of the AC motor.

14. The inductance measuring device according to any one of claims 1 to 13, characterized in that, Let the magnitude of the current vector, which is equivalent to the current flowing through the AC motor when the first voltage is applied, be |I1|. The rated voltage of the AC motor is set as V r The rated current is set as I r The excitation is set as Φ f The rated frequency is set as f r The control processing period of one time is set as t s , The voltage command generation unit calculates the magnitude of the first voltage command based on the following equations (1), (2), and (3). [Mathematical Expression 1] [Mathematical Expression 2] [Mathematical Expression 3] 。 15. The inductance measuring device according to any one of claims 1 to 14, characterized in that, After outputting the first voltage command to the power conversion unit, the voltage command generation unit outputs an inverse voltage command indicating a voltage with the same magnitude but opposite direction as the first voltage to the power conversion unit, thereby suppressing the generation of the driving force of the AC motor.

16. The inductance measuring device according to any one of claims 1 to 15, characterized in that, Before outputting the first voltage command to the power conversion unit, the voltage command generation unit outputs a command to apply a constant DC voltage in the direction of the d-axis of the AC motor to the power conversion unit, thereby fixing the AC motor.

17. The inductance measuring device according to any one of claims 1 to 16, characterized in that, The inductance calculation unit calculates the inductance of either the d-axis or the q-axis. When the inductance calculation unit calculates the inductance of the d-axis, the voltage command generation unit generates a voltage command that sets the phase of the second voltage command indicating the second voltage to 0° and outputs it to the power conversion unit. When the inductance calculation unit calculates the inductance of the q-axis, the voltage command generates a voltage command that sets the phase of the second voltage command to 90° and outputs it to the power conversion unit. This generates a current change on the axis to which the applied voltage to the AC motor changes from the first voltage to the second voltage.

18. The inductance measuring device according to any one of claims 1 to 17, characterized in that, The voltage command generation unit generates a first voltage command for controlling the power conversion unit by repeatedly applying a plurality of first voltages, differing in at least one of magnitude and phase, within a range specified based on the rated current of the AC motor. The inductance calculation unit calculates the inductance of the AC motor for each of the plurality of first voltages applied to the AC motor, and creates tabular data of inductance based on the calculation results.

19. An inductance measurement method, performed by an inductance measuring device comprising a voltage command generation unit for generating a voltage command for a power conversion unit, the inductance measuring device calculating the inductance of the AC motor based on a first current flowing through the AC motor when a first voltage is applied to the AC motor and a second current flowing through the AC motor when a second voltage is applied to the AC motor after the first voltage is applied, wherein the power conversion unit applies the voltage to the AC motor. The inductance measurement method is characterized by including: In the first step, the voltage command generation unit generates the first d-axis voltage command and the first q-axis voltage command based on a first voltage command indicating the first voltage and a predefined voltage segmentation reference. The first d-axis voltage command and the first q-axis voltage command are of equal quantity, and in the case of a 0 voltage command, the 0 voltage command is executed before the non-0 voltage commands. In the second step, the voltage command generation unit, based on the generated multiple first d-axis voltage commands and first q-axis voltage commands, repeatedly instructs the power conversion unit to apply voltage to the AC motor.

20. The inductance measurement method according to claim 19, characterized in that, The voltage segmentation reference is either the voltage segmentation reference on the same phase as the first voltage command, i.e., the first voltage segmentation reference, or the voltage segmentation reference on the d-axis and q-axis of the rotating coordinate system, i.e., the second voltage segmentation reference.

21. The inductance measurement method according to claim 20, characterized in that, In the first step, the first voltage command is divided into a plurality of first segmented voltage commands having the same phase as the first voltage command based on the first voltage segmentation reference. Each of the plurality of first segmented voltage commands is separated into a d-axis component and a q-axis component to generate a plurality of first d-axis voltage commands and first q-axis voltage commands.

22. The inductance measurement method according to claim 20, characterized in that, In the first step, the first voltage command is separated into the d-axis component and the q-axis component. Based on the second voltage segmentation reference, each of the d-axis component and the q-axis component of the first voltage command is segmented. If the number of the d-axis components of the segmented first voltage command is different from the number of the q-axis components of the segmented first voltage command, a 0 voltage command is added to the side with the smaller number, generating the same number of the first d-axis voltage commands and the first q-axis voltage commands.

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