Inductance measurement device and inductance measurement method

Abstract

An inductance measurement device (10) comprises: a power conversion unit (2) that applies voltage to an AC machine (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 machine on the basis of a first current flowing through the AC machine when a first voltage is applied to the AC machine and a second current flowing through the AC machine when a second voltage is applied to the AC machine after the first voltage is applied. The voltage command generation unit generates, on the basis of a first voltage command for commanding the first voltage and a predetermined voltage division reference, a plurality of and the same number of first d-axis voltage commands and first q-axis voltage commands of a rotation coordinate system, the first d-axis voltage commands and the first q-axis voltage commands being for commanding a d-axis voltage and a q-axis voltage, respectively, such that if a zero-voltage command is included, the zero voltage command is executed before a non-zero voltage command. On the basis of the generated plurality of first d-axis voltage commands and the first q-axis voltage commands, commands for voltage application to the AC machine is given a plurality of times to the power conversion unit.

Description

Inductance measuring device and inductance measuring method

[0001] The present disclosure relates to an inductance measurement device and an inductance measurement method for measuring the inductance of an AC machine.

[0002] In controlling an AC machine, information such as the inductance of the AC machine is used as a control parameter. Therefore, it is necessary to acquire the control parameters before starting control of the AC machine. Patent Literature 1 discloses a control device for a rotating machine that can measure the inductance of the rotating machine.

[0003] The control device described in Patent Document 1 repeatedly applies a plurality of voltage commands so that the d-axis current or the q-axis current becomes a target current, and then measures the inductance.

[0004] Specifically, in the control device described in Patent Document 1, a first voltage command (measurement preparation voltage command) is issued to the voltage application section multiple times to raise the shaft current of the rotating machine to the measurement point, and then a second voltage command (measurement voltage command) is issued to generate a minute current change, and the inductance is calculated from the current change and voltage.

[0005] Patent No. 5634620

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

[0007] Here, as a comparative example, a control operation in which the measurement accuracy of the d-axis current and the q-axis current deteriorates will be described with reference to Figures 2 and 3. Figure 2 shows an example of voltage commands for the d-axis and q-axis in the control operation of the comparative example, and Figure 3 shows an example of time variations in voltage and current when the control operation of the comparative example is executed. In the following description, the d-axis and q-axis may be collectively referred to as the dq-axis or the d-axis-q-axis.

[0008] When measuring the inductance when current is applied to both the d-axis and q-axis, it is necessary to simultaneously apply voltage to the d-axis and q-axis as a voltage command, using the voltage vector. However, when voltage commands are applied multiple times to the power conversion means that drives the AC machine and the axis current increases stepwise, if the number of non-zero voltage commands differs between the d-axis and the q-axis, for example, if the voltage commands for increasing the current on the d-axis and q-axis to the measurement point are voltage vectors as shown in Figure 2, the d-axis current I d When a non-zero voltage command is given twice, the measurement point is reached and the q-axis current I q For the q-axis current I, the measurement point is reached when a non-zero voltage command is given four times. Therefore, as shown in FIG. 3, a voltage application waiting time occurs on the d-axis, and the q-axis current I q When the measurement point is reached and the actual measurement is performed, the d-axis current I d The value indicated by the white circle (○) will be lower than the value at the original measurement point indicated by the black circle (●). Therefore, the measured value of the d-axis current will contain an error compared to the target value that we originally wanted to raise, which will be a factor in deteriorating the inductance measurement accuracy.

[0009] The present disclosure has been made in view of the above, and has an object to provide an inductance measuring device that can measure the inductance of an AC machine with high accuracy.

[0010] In order to solve the above-mentioned problems and achieve the object, an inductance measurement device according to the present disclosure includes a power conversion unit that applies a voltage to an AC machine, 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 machine based on a first current that flows through the AC machine when a first voltage is applied to the AC machine and a second current that flows through the AC machine when a second voltage is applied to the AC machine after the first voltage is applied, wherein the voltage command generation unit generates a first d-axis voltage command that commands a voltage on the d-axis of a rotating coordinate system and a first q-axis voltage command that commands a voltage on the q-axis based on a first voltage command that commands the first voltage and a predetermined voltage division standard, the voltage command generation unit generating a plurality of equal first d-axis voltage commands that command a voltage on the d-axis and a first q-axis voltage command that command a voltage on the q-axis, such that if a zero voltage command is included, the zero voltage command is executed before a non-zero voltage command, and further commands the power conversion unit to apply voltages to the AC machine a plurality of times based on the generated plurality of first d-axis voltage commands and first q-axis voltage commands.

[0011] The inductance measuring device according to the present disclosure has the effect of being able to measure the inductance of an AC machine with high accuracy.

[0012] FIG. 1 is a diagram showing an example of the configuration of an inductance measuring device according to a first embodiment; FIG. 2 is a diagram showing an example of voltage commands on the d-axis and q-axis in a control operation of a comparative example; FIG. 3 is a diagram showing an example of time changes in voltage and current when a control operation of a comparative example is being executed; FIG. 4 is a diagram showing steady-state inductance; FIG. 5 is a diagram showing differential inductance;

[0013] An inductance measuring device and an inductance measuring method according to embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0014] In the embodiments described below, the components of each phase of a 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 d-axis and q-axis. The d-axis is a reference direction in the rotating coordinate system, and is set, for example, to the direction of the field in the rotating coordinate system of a synchronous machine with a field, or to the maximum or minimum direction of the inductance in the rotating coordinate system of a reluctance-type synchronous machine without a field. These reference directions are referred to as θ e The reference direction θ e can be detected using known techniques, for example, the technique disclosed in Japanese Patent No. 4271397.

[0015] First Embodiment. Fig. 1 is a diagram showing an example of the configuration of an inductance measurement device 10 according to a first embodiment. The inductance measurement 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 conversion unit 5. The inductance measurement device 10 measures inductance to be used as a control parameter for an AC machine 11, such as an AC electric motor. Although not shown in Fig. 1, the AC machine 11 is assumed to be connected to a load machine. The hardware configuration of the inductance measurement device 10 is similar to that of a power conversion device that supplies three-phase AC power to the AC machine 11 to drive it. The function of measuring the inductance of the AC machine 11, which is realized by the inductance measurement device 10, may be included in the functions of the power conversion device that drives the AC machine 11.

[0016] The voltage command generating unit 1 generates voltage commands (V d * , V q * ) and then convert them into (V d * , V q * ) corresponding to the three-phase voltage command (V u * , V v * , V w * ) and outputs them to the power conversion unit 2. The voltage command generation unit 1 also generates voltage commands (V d * , V q * ) to the inductance calculation unit 4. The power conversion unit 2 generates three-phase AC voltages commanded by the voltage command input from the voltage command generation unit 1 and applies them to the AC machine 11. The current detection unit 3 detects the currents (I u , I v , I w The coordinate conversion unit 5 converts the three-phase current detected by the current detection unit 3 into a d-axis current (I d ) and q-axis current (I q) and outputs it to the inductance calculation unit 4. The inductance calculation unit 4 calculates the inductance of the AC machine 11 based on the d-axis voltage command and the q-axis voltage command input from the voltage command generation unit 1 and the d-axis current and the q-axis current input from the coordinate conversion unit 5.

[0017] In the inductance measurement device 10, the inductance calculation unit 4 calculates the inductance of the AC machine 11 based on the measured values ​​of the currents on each axis when both the d-axis and q-axis are energized. At this time, the voltage command generation unit 1 outputs three-phase voltage commands corresponding to the d-axis and q-axis voltage commands to the power conversion unit 2 multiple times to increase the currents on each axis to the measurement points. Furthermore, when increasing the currents on each axis to the measurement points and measuring them, a voltage is applied that can avoid a deterioration in the current measurement accuracy.

[0018] Next, the detailed operation of the inductance measuring device 10 according to this embodiment will be described.

[0019] In the following, the inductance of the AC machine 11 measured by the inductance measurement device 10 will be defined using two types of definitions shown in the following equations (1) and (2). Equation (1) is the origin gradient of the magnetic flux and current, and will be referred to as the steady-state inductance L. Equation (2) is the gradient of the local magnetic flux change and current change, and will be referred to as the differential inductance L'. These are shown in Figures 4 and 5. Figure 4 shows the steady-state inductance L, and Figure 5 shows the differential inductance L'.

[0020]

[0021]

[0022] From equations (1) and (2), the steady-state inductance L and the differential inductance L' have the relationship of equation (3).

[0023]

[0024] A flowchart of the operation of measuring inductance by the inductance measuring device 10 is shown in Fig. 6. Fig. 6 is a flowchart showing an example of the inductance measuring operation of the inductance measuring device 10 according to the first embodiment.

[0025] When measuring inductance, the inductance measuring device 10 first generates a first voltage vector command V1 which commands a measurement preparation voltage, which is a first voltage. * Based on this, the first divided voltage vector command V * [n1] (n1 = 1, 2, ...) is generated (step S11). Specifically, the voltage command generating unit 1 generates a measurement preparation voltage vector command V1 * Based on this, one or more first divided voltage vector commands V * Generate [n1] (n1 = 1, 2, ...).

[0026] The AC machine 11 is connected to a load machine, and it is desirable to be able to measure the inductance without causing vibration or noise. To do this, it is necessary to raise the current to the target measurement point by applying a voltage for an extremely short time. Therefore, the voltage vector command V * In many cases, V1 is a large voltage that exceeds the range of voltage that can be output by the inductance measurement device 10. For this reason, in the inductance measurement device 10, V1 * Based on this, one or more first divided voltage vector commands V * [n1] (n1 = 1, 2, ...) is generated and divided into multiple voltage applications. This reduces the magnitude of each voltage vector, making it possible to apply such a large voltage. Furthermore, multiple voltage applications cause the current to rise stepwise to the measurement point, and by measuring the current at each step of the rise and monitoring to see if an excessive current is flowing, it is possible to protect the inductance measurement device 10 and the AC machine 11.

[0027] The voltage command generator 1 generates a first divided voltage vector command V1 * The operation of generating [n1] (n1=1, 2, . . . ) will be described in detail later.

[0028] The inductance measuring device 10 then calculates a first divided voltage vector command V * Specifically, the voltage command generating unit 1 applies one or more first divided voltage vector commands (V * [1], V1 *[2], V1 * [3], ...) are sequentially applied to the power conversion unit 2. The power conversion unit 2 applies to the AC machine 11 voltages commanded by each of the one or more first divided voltage vector commands.

[0029] The operations in steps S11 and S12 will be described in detail using a specific example.

[0030] The voltage command generating unit 1 has a reference direction θ e and the first voltage vector command V * The first voltage vector command V1 is set. * is a voltage vector command for supplying a first current vector I1, which is a target current, to the AC machine 11. The target current is a current when the AC machine 11 outputs torque to the load machine. This first voltage vector command V1 * is set by the user via a UI (User Interface) not shown in FIG. 1 before the inductance measuring device 10 starts the inductance measurement operation, for example.

[0031] First voltage vector command V * The size of |V1 * |, reference direction θ e First voltage vector command V1 * The phase of θ v1 * , the voltage command generator 1 generates a first voltage vector command V * Any voltage division reference V st According to this, the size is V st A plurality of first divided voltage vector commands V1 that are the same in phase and are * [n1] (n1 = 1, 2, ...). Note that FIG. 7 shows the first voltage vector command V1 generated by the voltage command generating unit 1 of the inductance measuring device 10 according to the first embodiment. * 7 is a diagram showing an example of a division method of θ v is the first voltage vector command V * Phase θ v1 * That is, θ v = θ v1* The voltage division reference V st is the first voltage division criterion.

[0032] Here, the voltage division reference V st is set within the range of voltages that can be output by the inductance measuring device 10. For example, the voltage division reference V is set based on the rated voltage of the power conversion unit 2 and the rated voltage of the AC machine 11. st The rated voltage here is the voltage taking into consideration the wiring of the power conversion unit 2 and the AC machine 11. If the rated voltage is determined by the effective phase voltage value, the effective phase voltage value = magnitude of the voltage vector × 1 / √3, so √3 × rated voltage is set to V. st If the rated voltage is determined by the effective value of the line voltage, then the effective value of the line voltage = the magnitude of the voltage vector, so the rated voltage can be set to V st Just set it to

[0033] A first voltage vector command V1 corresponding to the first voltage command * In the dividing operation of (1), the voltage command generating unit 1 first generates a first divided voltage vector command V1 * [n1] Determine the size of each |V1 * |V st The quotient and remainder of the division by k1 (k1: integer) and V 1k Let |V1 * If the number of divisions of | is n1, then |V1 * |=k1×V st +V 1k Therefore, n1 = k1 + 1. First divided voltage vector command V1 * Size of [n1] | V1 * |[n1] is expressed by the following equation (4).

[0034]

[0035] The voltage command generator 1 then generates a first voltage vector command V * Phase θ v1 * Using V1 * [n1] is separated into a d-axis component and a q-axis component, and multiple d-axis voltage commands V 1d* [n1] = |V1 * |[n1] × cosθ v1 * and q-axis voltage command V 1q * [n1] = |V1 * |[n1] × sinθ v1 * By dividing in this way, the number of voltage commands for both the d and q axes becomes n1, and all voltage commands become non-zero.

[0036] The voltage command generator 1 generates the divided d-axis voltage command V 1d * [n1] and the q-axis voltage command V 1q * [n1], the reference direction θ e dq-three-phase coordinate transformation is performed based on the three-phase voltage command V u * , V v * and V w * Then, the voltage command generator 1 generates the generated three-phase voltage command V u * , V v * and V w * is output to the power conversion unit 2.

[0037] The power conversion unit 2 converts a three-phase voltage command V u * , V v * and V w * According to this, the voltage vector V * [n1] is applied to the AC machine 11.

[0038] In this way, the inductance measuring device 10 receives the first voltage vector command V * Divide the d-axis voltage command V 1d * [n1] and the q-axis voltage command V 1q * [n1] is generated, and the d-axis and q-axis voltage commands are repeatedly executed multiple times to apply a voltage to the AC machine 11. As a result, the d-axis current I 1dand q-axis current I 1q is changed as shown in Fig. 8 and is raised to the measurement point. Fig. 8 is a diagram showing an example of the operation of the inductance measurement device 10 according to the first embodiment, in which the inductance measurement device 10 applies a voltage to the AC machine 11 and raises the current to the first measurement point. Figs. 7 and 8 show the operation of the inductance measurement device 10 when the first voltage vector command V1 * 10 shows an example in which the above is executed four times.

[0039] 6, the inductance measuring device 10 next detects a first current vector I1 (step S13). Specifically, the current detecting unit 3 detects the first current vector I1. The first current vector I1 is determined by the first voltage vector command V1. * All d-axis voltage commands V obtained by dividing 1d * [n1] and the q-axis voltage command V 1q * This is the current vector at the time when [n1] is executed and the application of the measurement preparation voltage to the AC machine 11 is completed.

[0040] Next, the inductance measuring device 10 generates a second voltage vector command V2 that commands a measurement voltage, which is a second voltage. * Based on this, the second divided voltage vector command V * [n2] (n2 = 1, 2, ...) is generated (step S14), and the second divided voltage vector command V2 * [n2] is applied (step S15). Then, the inductance measurement device 10 detects the second current vector I2 (step S16). These steps S14 to S16 are the same processes as the above-mentioned steps S11 to S13. Second voltage vector command V2 * is the first voltage vector command V * Similarly, it is assumed that the value is set in advance.

[0041] Here, the second voltage vector command V * Regarding the first voltage vector command V * The voltage application should be performed so that a current that is changed by the amount of change ΔI used for inductance calculation from the current I1 at the time of application completion flows. *can be set arbitrarily. * | is the voltage division reference V st The following value may be set so that the voltage application is completed in one time. However, since the inductance of the AC machine 11 is large, V st If the voltage applied is not enough to cause a change in current, V st A value exceeding the first voltage vector command V * Similarly to the case of * If division is not necessary, the voltage command generator 1 generates the second voltage vector command V * V2 * Set it to [1].

[0042] A second voltage vector command V2 corresponding to the second voltage command * 9 shows an example of the case where the inductance measuring device 10 according to the first embodiment applies a voltage to the AC machine 11 to increase the current to the second measurement point. In steps S14 to S16, as shown in FIG. 9, the first voltage vector command V1 * The first current vector I (I 1d , I 1q ) is conducting, a second current vector I2 (I 2d , I 2q ) is changed to a state where it is conducting, causing a current change ΔI=I2-I1.

[0043] After detecting the second current vector I2 in step S16, the inductance measurement device 10 calculates the inductance of the AC machine 11 (step S17). Specifically, the inductance calculation unit 4 calculates the inductance of the AC machine 11 based on the second voltage vector command V2 * and the current change ΔI, the inductance is calculated. The calculated inductance is stored, for example, in a storage unit not shown in FIG. 1 so that it can be referenced when necessary, such as when driving the AC machine 11. The inductance measuring device 10 may display the inductance calculation result on a display device to notify the outside. Details of the inductance calculation process by the inductance calculation unit 4 will be described later.

[0044] When applying voltages as described in this embodiment, the number of divisions of the voltage vector commands for the d and q axes is the same, and therefore, as shown in Figures 7, 8, and 9, non-zero voltages are applied to the d and q axes the same number of times. This makes it possible for the d and q axes to simultaneously reach their target currents when the voltage application is completed, and prevents the current of one of the axes from dropping after the target current is reached.

[0045] In addition, the d-axis voltage command V 1d * [n1] and the q-axis voltage command V 1q * By using [n1], the currents reached by each voltage application are low, and the inductance is large, resulting in a long time constant. This allows the current to drop gradually from the completion of each voltage application to the next voltage application, allowing the current to rise appropriately with each voltage application.

[0046] Furthermore, since the n1 voltage applications do not include a 0 voltage command, it is possible to determine a measurement point midway through the n1 voltage applications. * [m1], V1 * [m1] is the first voltage command, V1 * [m1+1] is regarded as the second voltage command and the inductance is calculated. * [m1+1] is the first voltage command, V1 * [m1+2] is regarded as the second voltage command and inductance calculation is performed, V1 * This is repeated until the application of I is completed. In this way, it is possible to obtain the effect of simultaneously measuring not only the inductance due to the current vector I at the measurement point, but also the inductance due to the current vector on the way to I.

[0047] Next, the details of the inductance calculation process performed by the inductance calculation unit 4 will be described.

[0048] The inductance calculation unit 4 calculates the inductance on the d-axis and q-axis. If the voltage on one of the d- and q-axes is v, the current is i, the winding resistance is R, and the armature flux linkage is φ, the voltage equations for the d- and q-axes when the AC machine 11 is not rotating are expressed by equations (5) and (6), ignoring terms related to the rotational speed.

[0049]

[0050]

[0051] From equations (5) and (6), the magnetic flux change dφ is dφ = (v - Ri) dt. Also, the d-axis current change di d The change in q-axis magnetic flux due to q / di d and the q-axis current change di q The d-axis magnetic flux change due to d / di q If we assume that the magnetic flux change due to the interference between the d and q axes is sufficiently smaller than the magnetic flux change caused by the current change in each of the d and q axes and can be ignored, then the differential inductance L' can be calculated as shown in equations (7) and (8) in combination with the above equation (2).

[0052]

[0053]

[0054] When calculating the inductance of the AC machine 11 by applying a voltage using the inductance measuring device 10 according to this embodiment, the voltage vector command V * The magnetic flux change Δφ caused by [n2] (n2 = 1, 2, ...) is expressed as t s Then, the equations (9) and (10) are obtained.

[0055]

[0056]

[0057] Here, in particular, when measuring inductance when the current I1 is increased to a high current, the voltage corresponding to the resistance drop of RI1 in equations (9) and (10) is a sufficiently small value compared to V2, so approximate calculations such as equations (11) to (16) shown below can also be used.

[0058] If the resistance drop at the time of application of each voltage vector command is omitted and only the resistance drop at the time of application of the final voltage vector command is considered, calculations may be performed using equations (11) and (12), which are equivalent to the case where all voltage vector commands before division are applied by a single voltage application.

[0059]

[0060]

[0061] However, V 2d * and V 2q * is the dq axis voltage command before division, I 1d [n2] and I 1q [n2] is the current when the final voltage vector command is applied.

[0062] Alternatively, calculations may be performed as in equations (13) and (14), in which the resistance drop is entirely omitted.

[0063]

[0064]

[0065] Since equations (13) and (14) are equivalent to the case where all voltage vector command values ​​before division are applied in one voltage application, calculations may be performed as in equations (15) and (16).

[0066]

[0067]

[0068] According to the calculation formulas (11) to (16), the number of current measurement points can be reduced.

[0069] Furthermore, the differential inductance L' can be calculated from the magnetic flux change amount obtained from any of equations (9) to (16) and the current change amount ΔI during that time, as shown in equations (17) and (18).

[0070]

[0071]

[0072] Furthermore, because of the relationship in equation (3), it is possible to calculate the steady-state inductance L from the measurement results of the differential inductance L'. There are various possible actual calculation methods, but one method with a light calculation load is to define an approximate function of L(I) and express L(I) as the equation L'(I). For example, if L(I) is approximated by a linear function related to current, it can be expressed as L(I) = aI + b. Therefore, from equation (3), L'(I) = aI + (aI + b) = 2aI + b, and it can be seen that L(I) is a function with the same intercept as L'(I) and a slope of 1 / 2.

[0073] Although a linear function has been used as an example of an approximate function, calculations can also be performed assuming any function such as a higher-order function or a logarithmic function.

[0074] L'(I) as a function of current can be calculated as an approximate function using a method such as the least squares method if there are measurement results of L'(I1) for each of a plurality of I1.

[0075] Measurement of multiple L'(I1) can be performed by, for example, measuring multiple |V1 * | and multiple |V1 * A plurality of first voltage vector commands V1 according to | * Then, L' for a plurality of I1's can be measured according to the first embodiment using the above formula.

[0076] Alternatively, as described above, in inductance measurement by the inductance measuring device 10 according to this embodiment, since the n1 voltage applications do not include a 0 voltage command, it is possible to set the measurement point midway through the n1 voltage applications. Therefore, if the inductance for each current up to I1 is measured simultaneously, rather than just the inductance at a single point due to I1 at the measurement point, multiple L'(I) can be obtained.

[0077] Furthermore, according to the inductance calculation method using the inductance measuring device 10 of this embodiment, the application time t s Since the time may be set to an extremely short time, it is possible to perform inductance measurement while minimizing vibration and noise of the AC machine 11.

[0078] As described above, the inductance measuring device 10 according to this embodiment receives the first voltage vector command V1 * The voltage division reference V st The first divided voltage vector command V * [n1] is generated, and then separated into a d-axis component and a q-axis component to generate voltage commands for the d-axis and q-axis, respectively. This makes the number of voltage commands for the d-axis and the number of voltage commands for the q-axis the same, preventing a deterioration in the inductance measurement accuracy due to the measured current value on one axis dropping below the actual value.

[0079] Second Embodiment Next, a second embodiment will be described. The configuration of the inductance measuring device according to the second embodiment is the same as that of the first embodiment (see FIG. 1), but the inductance measurement operation is partially different from that of the first embodiment. In this embodiment, the differences from the first embodiment will be described.

[0080] The inductance measuring device 10 according to the second embodiment uses the first divided voltage vector command V * Generation process of [n1] (step S11 in FIG. 6), second divided voltage vector command V2 * The process of generating [n2] (step S14 in FIG. 6) differs from that of the first embodiment. *Generation of [n1] and second divided voltage vector command V2 * Therefore, in this embodiment, the first divided voltage vector command V1 * An example of a process for generating [n1] will be explained, and the second divided voltage vector command V2 * The process for generating [n2] will not be described.

[0081] The voltage command generator 1 generates a first divided voltage vector command V * When generating [n1], first, the voltage vector command V1 * is separated into the d-axis component and the q-axis component, and the d-axis voltage command V 1d * and q-axis voltage command V 1q * Ask for.

[0082] Next, the voltage command generating unit 1 divides the voltage commands for each axis in the same procedure as in the first embodiment. Specifically, the voltage command generating unit 1 divides the voltage commands for each axis by a voltage division reference V stdq According to this, the d-axis voltage command V 1d * and q-axis voltage command V 1q * are divided into a plurality of first d-axis divided voltage commands V 1d * [n 1d ](n 1d = 1, 2, ...) and a plurality of first q-axis divided voltage commands V 1q * [n 1q ](n 1q = 1, 2, ...) is calculated. stdq is the second voltage division criterion.

[0083] Here, the voltage division reference V stdq may be set within the range of the d-axis voltage that the inductance measuring device 10 can output. For example, it may be set to 1 / √2× the rated voltage of the power conversion unit 2 or 1 / √2× the rated voltage of the AC machine 11. By setting it in this way, the d-axis voltage after division becomes the maximum value V stdqEven if the voltage vector is taken as above, the magnitude of the combined voltage vector will not exceed the rated voltage. As in the first embodiment, the rated voltage here is a voltage that takes into consideration the wiring of the power conversion unit 2 and the AC machine 11.

[0084] d-axis voltage command V 1d * Size of |V 1d * |V stdq The quotient and remainder when divided by k are respectively 1d (k 1d : an integer) and V 1kd Then, the first d-axis divided voltage command V 1d * [n 1d ] is expressed by the following formula (19): 1d = k 1d It's +1.

[0085]

[0086] In addition, the q-axis voltage command V 1q * Size of |V 1q * |V stdq The quotient and remainder when divided by k are respectively 1ｑ (k 1q : an integer) and V 1kq Then, the first q-axis divided voltage command V 1q * [n 1q ] is expressed by the following formula (20): 1q = k 1q It's +1.

[0087]

[0088] Next, the voltage command generating unit 1 calculates n 1d and 1q Here, we compare n 1d <n 1q The following will be explained using the case of

[0089] n 1d <n 1q In this case, the first d-axis divided voltage command V 1d * [n 1d ] is the first q-axis divided voltage command V1q * [n 1q ], the voltage command generating unit 1 calculates the missing n 1q -n 1d Add 0 voltage command to the number of 1q Specifically, the voltage command generator 1 adds a zero voltage command to the first half of the d-axis voltage vector command to generate a new first d-axis divided voltage command V 1dd * [n 1ｑ ](n 1q = 1, 2, ...).

[0090]

[0091] Here, n 1d <n 1q The case of n 1d >n 1q In the case of V 1q * [n 1q ] is subjected to the same processing to add a zero voltage command, and a new q-axis voltage command V 1qq * [n 1d ](n 1d = 1, 2, ...) and 1d = n 1q In this case, the voltage command generating unit 1 does not perform the process of adding a zero voltage command.

[0092] d-axis divided voltage command V 1dd * [n 1q ] and the q-axis divided voltage command V 1q * [n 1q ], as shown in FIGS. 10 and 11, on the d axis, first, the 0 voltage command (V 1dd * [1], V 1dd * [2]) is applied, and then V 1d * [n 1d ]corresponding to V 1dd * [n 1q]. Therefore, the timing of voltage application completion is synchronized between the d and q axes, and the target current is reached simultaneously on the d and q axes at the time of voltage application completion. Therefore, as in the first embodiment, it is possible to prevent a deterioration in the inductance measurement accuracy due to the current measurement value on one axis dropping below the actual value.

[0093] Third Embodiment Next, a third embodiment will be described. The configuration of the inductance measuring device according to the third embodiment is the same as that of the first embodiment (see FIG. 1). In this embodiment, differences from the first embodiment will be described.

[0094] Before executing the operation shown in the flowchart of FIG. 6 described in the first embodiment, the voltage command generating unit 1 according to the third embodiment executes the first voltage vector command to calculate the magnitude |V1 of the first voltage vector command based on the current target value |I1| to be reached. * Calculate |.

[0095] The voltage command generator 1 determines the magnitude |V1 of the first voltage vector command. * When calculating |, first calculate the effective value φ of the interlinkage magnetic flux created by the inductance. r Here, the rated voltage of the AC machine 11 is V r [Vrms], rated current is I r [Arms], field is φ f [Wb], rated frequency is f r If the frequency is [Hz], the effective value of the flux linkage created by the inductance is φ, assuming that during rated operation a terminal voltage equivalent to the rated voltage is applied, the rated current flows, and the motor is driven at the rated frequency. r can be calculated as in equation (22).

[0096]

[0097] In the case of a reluctance AC machine without a field magnet, φ f = 0 and use equation (22). The voltage command generator 1 converts the inductance calculated according to equation (23) into the rated inductance L r It is stipulated that:

[0098]

[0099] Then, the voltage command generator 1 calculates the rated inductance L r and the current target value |I1|, the magnitude |V1 of the first voltage vector command is calculated as shown in equation (24). * Calculate |.

[0100]

[0101] The voltage command generator 1 determines the magnitude |V1 of the first voltage vector command. * After calculating |, this |V1 * | is used to perform the inductance measurement described in the first embodiment (steps S11 to S17 shown in FIG. 6).

[0102] In this way, before starting to measure the inductance, the magnitude |V1 of the first voltage vector command is calculated according to equation (24). * By calculating |, it is possible to know the approximate value of the magnitude of the voltage vector command required for each current when the inductance is unknown, and the first voltage vector command V1 required to reach the target current I1 can be calculated. * This can reduce the number of adjustment steps, and also prevent excessive current that could destroy the device from flowing.

[0103] The magnitude of the first voltage vector command |V1 * The calculation of | may be performed outside the voltage command generation unit 1. For example, a voltage command calculation unit may be separately provided, and the voltage command calculation unit may calculate the magnitude |V1 of the first voltage vector command. * | and output it to the voltage command generating unit 1.

[0104] Also, the magnitude of the first voltage vector command |V1 * After the calculation of |, the inductance is measured by the method described in the first embodiment, but the inductance may be measured by the method described in the second embodiment.

[0105] Fourth Embodiment Next, a fourth embodiment will be described. The configuration of the inductance measuring device according to the fourth embodiment is the same as that of the first embodiment (see FIG. 1). In this embodiment, differences from the first embodiment will be described.

[0106] FIG. 12 is a flowchart showing an example of an inductance measurement operation of the inductance measurement device 10 according to the fourth embodiment.

[0107] 12 , the inductance measuring device 10 according to the fourth embodiment first applies a fixing voltage to the d-axis (step S21). Specifically, the voltage command generating unit 1 generates a voltage command instructing application of a fixing voltage to the d-axis and outputs the voltage command to the power converting unit 2. In accordance with the voltage command from the voltage command generating unit 1, the power converting unit 2 applies a DC voltage to the AC machine 11 as a fixing voltage in the d-axis direction at sufficiently long time intervals.

[0108] Next, the inductance measuring device 10 performs a reflux operation of the current of the AC machine 11 (step S22). Specifically, the gate voltage of the power module in the power conversion unit 2 is cut off to set the current flowing through the AC machine 11 to zero.

[0109] Next, the inductance measuring device 10 performs an operation of measuring the inductance of the AC machine 11 (step S23). In this step S23, the inductance of the AC machine 11 is measured by the method described in the first embodiment, that is, the method shown in steps S11 to S17 in Fig. 6. Note that the inductance may also be measured by the method described in the second embodiment.

[0110] Next, the inductance measuring device 10 performs a return operation of the current of the AC machine 11, similar to step S22, to set the current flowing through the AC machine 11 to zero (step S24). This return operation can instantly set the current of the AC machine 11 to zero, thereby further suppressing vibration and noise in the drive unit of the AC machine 11.

[0111] Next, the inductance measuring device 10 applies a reverse voltage command (step S25). Specifically, the voltage command generating unit 1 generates a voltage vector command that commands a voltage in the reverse direction to that during inductance measurement, and outputs the voltage to the power converting unit 2. The power converting unit 2 then applies the commanded voltage to the AC machine 11. The voltage vector command V output by the voltage command generating unit 1 in step S25 is inv * is V inv *= -V1 * -V2 * By this process, even if the vibration and noise of the shaft cannot be sufficiently suppressed by setting the current to 0 during the return operation, a driving force in the opposite direction to that during inductance measurement is generated, thereby making it possible to further suppress the vibration and noise.

[0112] Next, the inductance measuring device 10 performs a reflux operation similar to steps S22 and S24 (step S26).

[0113] According to the fourth embodiment described above, it is possible to further suppress vibration and noise of the AC machine 11 compared to the first to third embodiments, and to perform inductance measurement more accurately.

[0114] 12, the processes other than step S23 may be selected as appropriate depending on the status of the AC machine 11 and the devices connected to the AC machine 11. For example, steps S21 and S22 may be omitted if it is clear that the drive unit of the AC machine 11 is fixed before the start of measurement. Steps S24 to S26 may be omitted if the AC machine 11 is difficult to drive, for example, if the inertia of the rotating shaft is large in the case of a rotary machine, or if the mass of the mover is large in the case of a direct current motor.

[0115] Fifth Embodiment Next, a fifth embodiment will be described. The configuration of the inductance measuring device according to the fifth embodiment is the same as that of the first embodiment (see FIG. 1). In this embodiment, differences from the first embodiment will be described.

[0116] In the fifth embodiment, a case will be described in which only one of the d-axis inductance and the q-axis inductance is measured when current is applied to both the d-axis and q-axis by any of the methods described in the first to fourth embodiments. In the fifth embodiment, the second voltage vector command V2 * Phase θ v2 * The setting method is different.

[0117] When only measuring the d-axis inductance, the inductance measuring device 10 according to the fifth embodiment measures the θ v2 *= 0 [deg], and when only measuring the q-axis inductance, θ v2 * In other words, the current is changed only in the d-axis direction or only in the q-axis direction, and the d-axis inductance or the q-axis inductance is measured.

[0118] In the derivation of the above equations (5) and (6), the d-axis current change di d The change in q-axis magnetic flux due to q / di d , and the q-axis current change di q The d-axis magnetic flux change due to d / di q The magnetic flux change due to the interference between the d and q axes is assumed to be negligible because it is sufficiently smaller than the magnetic flux change caused by the current change in each of the d and q axes. However, for example, if you want to measure inductance more accurately to compare with the results of magnetic field analysis, you can make the current change only in the d-axis direction or only in the q-axis direction, thereby eliminating the influence of the magnetic flux change due to the interference between the d and q axes and making it possible to perform a more accurate inductance calculation.

[0119] Sixth Embodiment Next, a sixth embodiment will be described. The configuration of the inductance measuring device according to the sixth embodiment is the same as that of the first embodiment (see FIG. 1). In this embodiment, differences from the first embodiment will be described.

[0120] In the inductance measuring device 10 according to the sixth embodiment, the first voltage vector command V1 generated by the voltage command generating unit 1 is * The size of |V1 * |V1 |, and a plurality of values ​​|V1 |V2 are set so that current vectors of a plurality of magnitudes in the range from 0 to the rated current of the AC machine 11 can be passed. * |, and the first voltage vector command V * The phase of θ v1 * Then, a plurality of phases ranging from 0 to 90 degrees are expressed as θ v1 * and set these |V1 * | and θ v1 *Inductance measurements are performed for all combinations of

[0121] That is, the voltage command generator 1 determines the magnitude |V1 * | and phase θ v1 * While changing the first voltage vector command V * The voltage command generator 1 repeatedly generates the second voltage vector command V2 * The magnitude and phase of the first voltage vector command V1 generated by the voltage command generator 1 are fixed. * For each of these, the inductance is calculated using the method described in the first embodiment.

[0122] Then, the inductance calculation unit 4 calculates all I 1d and I 1q The inductance measurement results are tabulated to create table data of inductance.

[0123] First voltage vector command V * The size of |V1 * |, a plurality of values ​​are set so that current vectors of a plurality of magnitudes in the range from 0 to the rated current of the AC machine 11 can be passed, and the phase θ v1 * Since a plurality of phases are set in the range of 0 to 90 degrees as * This covers all the voltage vectors that the AC machine 11 can take while it is driving. According to the sixth embodiment, table data covering all the inductances that the AC machine 11 can take while it is driving can be obtained.

[0124] The voltage command generator 1 may generate the first divided voltage vector command and the second divided voltage vector command in the procedure explained in the second embodiment.

[0125] Next, hardware for realizing the inductance measuring device 10 described in the first to sixth embodiments will be described.

[0126] The power conversion unit 2 of the inductance measurement device 10 is realized by, for example, an inverter. The current detection unit 3 of the inductance measurement device 10 is realized by, for example, a current sensor.

[0127] The voltage command generating unit 1, the inductance calculating unit 4, and the coordinate converting unit 5 of the inductance measuring device 10 are realized, for example, by a processor 91 and a memory 92 shown in Fig. 13. Fig. 13 is a diagram showing an example of hardware that realizes the inductance measuring device 10 according to the first to sixth embodiments.

[0128] Examples of the processor 91 include a CPU (Central Processing Unit, also referred to as a central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, or DSP (Digital Signal Processor)) or a system LSI (Large Scale Integration). Examples of the memory 92 include non-volatile or volatile semiconductor memory such as RAM (Random Access Memory), ROM (Read Only Memory), and flash memory, a magnetic disk, etc.

[0129] The voltage command generation unit 1, inductance calculation unit 4, and coordinate conversion unit 5 of the inductance measurement device 10 described in each embodiment are realized by the processor 91 executing a program for realizing each of these units. The program for realizing the voltage command generation unit 1, inductance calculation unit 4, and coordinate conversion unit 5 of the inductance measurement device 10 is stored in advance in the memory 92. The processor 91 reads out and executes this program from the memory 92, thereby operating as the voltage command generation unit 1, inductance calculation unit 4, and coordinate conversion unit 5 of the inductance measurement device 10.

[0130] Although the voltage command generation unit 1, inductance calculation unit 4, and coordinate conversion unit 5 of the inductance measurement device 10 have been described as being implemented using a general-purpose processor 91 and memory 92, these units may also be implemented using dedicated processing circuits. Examples of dedicated processing circuits include a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), and an FPGA (Field Programmable Gate Array). Each unit of the inductance measurement device may also be implemented using a combination of two or more of these processing circuits. Furthermore, the voltage command generation unit 1, inductance calculation unit 4, and coordinate conversion unit 5 of the inductance measurement device 10 may also be implemented using a combination of the processor 91 and memory 92 shown in FIG. 13 and a dedicated processing circuit. For example, the voltage command generation unit 1 and inductance calculation unit 4 may be implemented using the processor 91 and memory 92, and the coordinate conversion unit 5 may be implemented using a dedicated processing circuit.

[0131] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other. It is also possible to omit or modify parts of the configurations as long as they do not deviate from the gist of the invention.

[0132] REFERENCE SIGNS LIST 1 voltage command generation unit, 2 power conversion unit, 3 current detection unit, 4 inductance calculation unit, 5 coordinate conversion unit, 10 inductance measurement device, 11 AC machine

Claims

1. A reactance measurement device comprising: a power conversion unit that applies a voltage to an AC machine; 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 machine based on a first current flowing through the AC machine when a first voltage is applied to the AC machine and a second current flowing through the AC machine when a second voltage is applied to the AC machine after the first voltage application. The voltage command generation unit generates a first voltage command for commanding the first voltage, a first d-axis voltage command for commanding the voltage of the d-axis in the rotating coordinate system, and a first q-axis voltage command for commanding the voltage of the q-axis based on a predetermined voltage division criterion, the number of which is plural and the same, and when including a zero voltage command, the zero voltage command is executed before non-zero voltage commands. Further, based on the plurality of generated first d-axis voltage commands and the first q-axis voltage commands, the voltage application to the AC machine is commanded to the power conversion unit a plurality of times.

2. The reactance measurement device according to claim 1, wherein the voltage division criterion is a first voltage division criterion that is a voltage division criterion having the same phase as the first voltage command or a second voltage division criterion that is a voltage division criterion on the d-axis and the q-axis of the rotating coordinate system.

3. The reactance measurement device according to claim 2, wherein the voltage command generation unit divides the first voltage command into a plurality of first divided voltage commands having the same phase as the first voltage command based on the first voltage division criterion, and separates each of the plurality of first divided voltage commands into a component of the d-axis and a component of the q-axis to generate a plurality of the first d-axis voltage commands and the first q-axis voltage commands.

4. The reactance measurement device according to claim 2 or 3, wherein the voltage command generation unit generates a plurality of and the same number of second d-axis voltage commands for commanding the voltage of the d-axis and second q-axis voltage commands for commanding the voltage of the q-axis based on a second voltage command for commanding the second voltage and the first voltage division criterion. Further, based on the plurality of generated second d-axis voltage commands and the second q-axis voltage commands, the voltage application to the AC machine is commanded to the power conversion unit a plurality of times.

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

6. The inductance measuring device according to any one of claims 2 to 5, wherein the first voltage division reference is 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, wherein the first voltage division reference is the rated voltage of the AC machine.

8. The voltage command generation unit separates the first voltage command into a d-axis component and a q-axis component, divides each of the d-axis component of the first voltage command and the q-axis component of the first voltage command based on the second voltage division reference, and when the number of the d-axis components of the first voltage command after division is different from the number of the q-axis components of the first voltage command after division, adds a 0 voltage command to the side with the smaller number to generate the same number of the first d-axis voltage commands and the first q-axis voltage commands. The inductance measuring device according to claim 2, wherein:

9. The voltage command generation unit generates a plurality and the same number of second d-axis voltage commands for commanding the voltage of the d-axis and second q-axis voltage commands for commanding the voltage of the q-axis based on a second voltage command for commanding the second voltage and the second voltage division reference, and further commands the power conversion unit to apply a voltage to the AC machine a plurality of times based on the plurality of generated second d-axis voltage commands and the second q-axis voltage commands. The inductance measuring device according to claim 8, wherein:

10. The voltage command generation unit separates the second voltage command into a d-axis component and a q-axis component, divides each of the d-axis component of the second voltage command and the q-axis component of the second voltage command based on the second voltage division criterion, and when the number of the d-axis components of the second voltage command after division is different from the number of the q-axis components of the second voltage command after division, adds a zero voltage command to the side with the smaller number to generate the same number of the second d-axis voltage commands and the second q-axis voltage commands, and further commands the voltage application to the AC machine to the power conversion unit a plurality of times based on the generated plurality of the second d-axis voltage commands and the second q-axis voltage commands. The inductance measurement device according to claim 9, characterized in that.

11. The voltage command generation unit adds the zero voltage command so that the zero voltage command is executed first. The inductance measurement device according to claim 8 or 10, characterized in that.

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

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

14. When the voltage command generation unit sets the magnitude of the current vector equivalent to the energization current when the first voltage is applied to the AC machine as |I1|, and sets the rated voltage of the AC machine as V r , the rated current as I r , the field flux as φ f , the rated frequency as f r , and the control processing cycle for one time as t s , the inductance measurement device according to any one of claims 1 to 13, wherein the magnitude of the first voltage command is calculated based on the following formulas (1), (2), and (3).

15. After outputting the first voltage command to the power conversion unit, the voltage command generation unit outputs a reverse voltage command for commanding a voltage having the same magnitude as the first voltage and the opposite direction to the power conversion unit to suppress the generation of the driving force of the AC machine. The inductance measurement device according to any one of claims 1 to 14, characterized in that.

16. Before outputting the first voltage command to the power conversion unit, the voltage command generation unit outputs a command for applying a constant DC voltage in the d-axis direction of the AC machine to the power conversion unit to fix the AC machine. The inductance measurement device according to any one of claims 1 to 15, characterized in that.

17. 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 for commanding the second voltage, sets the phase of the second voltage command to 0 deg, and outputs it to the power conversion unit. When the inductance calculation unit calculates the inductance of the q-axis, the voltage command generation unit generates a voltage command for commanding the second voltage, sets the phase of the second voltage command to 90 deg, and outputs it to the power conversion unit, and causes a current change when the applied voltage to the AC machine changes from the first voltage to the second voltage to occur on the axis for which inductance is calculated. The inductance measuring device according to any one of claims 1 to 16, characterized in that 18. The voltage command generation unit generates the first voltage command for controlling the power conversion unit so that a plurality of the first voltages having at least one of magnitude and phase different within a range determined based on the rated current of the AC machine are repeatedly applied to the AC machine. The inductance calculation unit calculates the inductance of the AC machine for each of the plurality of the first voltages applied to the AC machine, and creates table data of the inductance based on the calculation results. The inductance measuring device according to any one of claims 1 to 17, characterized in that 19. An inductance measurement method executed by an inductance measurement device that includes a voltage command generation unit that generates a voltage command for a power conversion unit that applies a voltage to an AC machine, and calculates the inductance of the AC machine based on a first current flowing through the AC machine when a first voltage is applied to the AC machine and a second current flowing through the AC machine when a second voltage is applied to the AC machine after the first voltage application, the method comprising: a first step in which the voltage command generation unit generates a first voltage command for commanding the first voltage and, based on a determined voltage division criterion, a first d-axis voltage command for commanding the voltage of the d-axis in the rotating coordinate system and a first q-axis voltage command for commanding the voltage of the q-axis, the number of the first d-axis voltage commands and the number of the first q-axis voltage commands being plural and the same, and when including a zero voltage command, the zero voltage command being generated so as to be executed before a non-zero voltage command; and a second step in which the voltage command generation unit commands the voltage application to the AC machine to the power conversion unit a plurality of times based on the plurality of generated first d-axis voltage commands and the first q-axis voltage commands. The inductance measurement method is characterized by including the above steps.

20. The voltage division criterion is a first voltage division criterion that is a voltage division criterion having the same phase as the first voltage command or a second voltage division criterion that is a voltage division criterion on the d-axis and the q-axis of the rotating coordinate system. The inductance measurement method according to claim 19 is characterized by this.

21. In the first step, the first voltage command is divided into a plurality of first divided voltage commands having the same phase as the first voltage command based on the first voltage division criterion, and each of the plurality of first divided voltage commands is separated into a component of the d-axis and a component of the q-axis to generate the plurality of first d-axis voltage commands and the first q-axis voltage commands. The inductance measurement method according to claim 20 is characterized by this.

22. In the first step, the first voltage command is separated into a d-axis component and a q-axis component, and each of the d-axis component of the first voltage command and the q-axis component of the first voltage command is divided based on the second voltage division criterion. When the number of the d-axis components of the first voltage command after division is different from the number of the q-axis components of the first voltage command after division, a zero voltage command is added to the side with the smaller number to generate the same number of the first d-axis voltage commands and the first q-axis voltage commands. The inductance measurement method according to claim 20, characterized in that.

Images