Testing equipment and testing method

Abstract

To enable analyzing a change in characteristic of a winding of a test object even in the case that magnetic saturation has occurred.SOLUTION: A test device 1 has: an impulse voltage application-purpose capacitor Cs with one end connected to an external terminal T2; a switch SW and current limit resistor R that are connected in series between the other end of the impulse voltage application-purpose capacitor Cs and an external terminal T1; a measurement unit 4 that measures a voltage Vcd between the external terminal T1 and external terminal T2, and a voltage Vcs between both ends of the impulse voltage application-purpose capacitor; and a parameter calculation unit 5. The parameter calculation unit 5 is configured to calculate a time-variant change in at least one value of an equivalent inductor Ld, equivalent capacitor Cd and equivalent resistor Rd representing equivalently a winding 11 on the basis of measurement values of the voltage Vcd and voltage Vcs measured by the measurement unit 4.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a test device and a test method, and more particularly to a test device and a test method for measuring the characteristics of windings of products and components configured with windings (coils), such as rotating machines such as electric motors and generators, and transformers. [Background technology]

[0002] Conventionally, as a test device for measuring the characteristics of windings of rotating machines such as electric motors and generators, an impulse winding test device is known that calculates the multiplication value LC (LC value) of inductance L and capacitance C and the multiplication value RC (RC value) of resistance R and capacitance C in an equivalent circuit formed by the winding under test and the internal circuit of the test device based on the change in voltage when an impulse voltage is applied to the winding (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4508211 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional impulse winding testing devices, such as those described in Patent Document 1, can calculate the LC and RC values, which are the multiplication values ​​of each parameter (inductance L, capacitance C, and resistance R) related to the winding under test, but cannot calculate each parameter individually.

[0005] Generally, when magnetic saturation occurs in the winding under test, parameters such as the inductance of the winding change. However, conventional impulse winding test devices cannot accurately calculate the winding parameters when magnetic saturation occurs.

[0006] The present invention has been made in view of the above-mentioned problems, and aims to make it possible to analyze changes in the characteristics of a winding under test even when magnetic saturation occurs. [Means for solving the problem]

[0007] a switch connected between the other end of the impulse voltage application capacitor and the first external terminal; a current limiting resistor connected in series with the switch between the other end of the impulse voltage application capacitor and the first external terminal; an instruction input unit that turns on the switch in response to an instruction to start a test; a measurement unit that measures a first voltage between the first external terminal and the second external terminal and a second voltage across the impulse voltage application capacitor; and a test device that measures a change over time in at least one value of the equivalent inductor, the equivalent capacitor, and the equivalent resistance when the winding is equivalently represented by an inductor connected between the first external terminal and the second external terminal, a capacitor connected between the first external terminal and the second external terminal, and a resistor connected in series with the equivalent inductor between the first external terminal and the second external terminal, The device has a parameter calculation unit that performs calculations based on measured values ​​of the first voltage and the second voltage measured by the measurement unit, and a memory unit that stores measurement information including the measured values ​​of the first voltage and the second voltage measured by the measurement unit and the value of the equivalent capacitor, wherein the parameter calculation unit calculates the value of at least one of the equivalent inductor and the equivalent resistance per unit time by performing regression analysis based on an equation for the transient response of the first voltage and an equation for the transient response of the second voltage in an equivalent circuit formed by the equivalent inductor, the equivalent capacitor, and the equivalent resistance of the winding, the impulse voltage application capacitor, and the current limiting resistor for the predetermined period, using the measured values ​​of the first voltage and the measured value of the second voltage per unit time stored in the memory unit during a predetermined period from when the switch is turned on until when resonance based on the equivalent inductor, the equivalent capacitor, and the equivalent resistance of the winding starts. [Effects of the Invention]

[0008] The test device according to the present invention makes it possible to analyze changes in the characteristics of the winding under test even when magnetic saturation occurs. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing a configuration of a test device according to an embodiment of the present invention; [Figure 2] FIG. 10 is a diagram showing an equivalent circuit when a winding to be tested is connected to a test device. [Figure 3] FIG. 10 is a diagram showing an example of the characteristics of the voltage Vcd across the winding when an impulse voltage is applied between the external terminals with the winding connected to a test device. [Figure 4] FIG. 10 is a diagram for explaining a method for calculating an equivalent capacitance Cd of a winding. [Figure 5] FIG. 10 is a diagram showing an example of the analysis results of the equivalent capacitor Cd of the windings obtained by a test device. [Figure 6] FIG. 10 is a diagram showing an example of the analysis results of the equivalent capacitor Cd of the windings obtained by a test device. [Figure 7] FIG. 10 is a diagram showing an example of the analysis results of the equivalent capacitor Cd of the windings obtained by a test device. [Figure 8] 10 is a diagram showing an example of the analysis results of the equivalent inductor Ld and the equivalent resistance Rd of the windings obtained by a test device when no magnetic saturation occurs in the windings. FIG. [Figure 9] 10 is a diagram showing an example of the analysis results of the equivalent inductor Ld and the equivalent resistance Rd of the windings obtained by a test device when no magnetic saturation occurs in the windings. FIG. [Figure 10] 10 is a diagram showing an example of the analysis results of the equivalent inductor Ld and the equivalent resistance Rd of the windings obtained by a test device when no magnetic saturation occurs in the windings. FIG. [Figure 11] 10 is a diagram showing an example of the analysis results of the equivalent inductor Ld and the equivalent resistance Rd of the windings obtained by a test device when magnetic saturation occurs in the windings. FIG. [Figure 12]10 is a diagram showing an example of the analysis results of the equivalent inductor Ld and the equivalent resistance Rd of the windings obtained by a test device when magnetic saturation occurs in the windings. FIG. [Figure 13] 10 is a diagram showing an example of the analysis results of the equivalent inductor Ld and the equivalent resistance Rd of the windings obtained by a test device when magnetic saturation occurs in the windings. FIG. [Figure 14] 10 is a diagram showing an example of waveforms in which the values ​​of the equivalent inductor Ld and the equivalent resistance Rd of the winding calculated by the test device are expressed in another format. FIG. [Figure 15] 10 is a diagram showing an example of waveforms in which the values ​​of the equivalent inductor Ld and the equivalent resistance Rd of the winding calculated by the test device are expressed in another format. FIG. [Figure 16] FIG. 2 is a diagram illustrating an example of a display screen of a test device. [Figure 17] 10 is a flowchart showing the flow of a winding analysis method using a test device. DETAILED DESCRIPTION OF THE INVENTION

[0010] 1. Overview of the embodiment First, a typical embodiment of the invention disclosed in this application will be outlined. In the following description, for example, reference numerals in the drawings corresponding to components of the invention are written in parentheses.

[0011] [1] A test device (1) according to a representative embodiment of the present invention comprises a first external terminal (T1) to which one terminal of a winding (11) to be tested is connected, a second external terminal (T2) to which the other terminal of the winding is connected, an impulse voltage application capacitor (Cs) having one end connected to the second external terminal, a switch (SW) connected between the other end of the impulse voltage application capacitor and the first external terminal, a current limiting resistor (Rs) connected in series with the switch between the other end of the impulse voltage application capacitor and the first external terminal, and a switch (SW) connected in response to a command to start a test. a command input unit (3) that turns on the switch in response to the command; a measurement unit (4) that measures a first voltage (Vcd) between the first external terminal and the second external terminal and a second voltage (Vcs) across the impulse voltage application capacitor; and when the winding is equivalently represented by an equivalent inductor (Ld) connected between the first external terminal and the second external terminal, an equivalent capacitor (Cd) connected between the first external terminal and the second external terminal, and an equivalent resistance (Rd) connected in series with the equivalent inductor between the first external terminal and the second external terminal, a parameter calculation unit (5) that calculates a change over time in a value of at least one of the equivalent inductor, the equivalent capacitor, and the equivalent resistance based on the measured values ​​of the first voltage and the second voltage measured by the measurement unit; and a storage unit that stores measurement value information including the measured values ​​of the first voltage and the second voltage measured by the measurement unit, and a value of the equivalent capacitor, wherein the parameter calculation unit performs a regression analysis based on an equation for a transient response of the first voltage and an equation for a transient response of the second voltage in an equivalent circuit formed by the equivalent inductor, the equivalent capacitor, and the equivalent resistance of the winding, the impulse voltage application capacitor, and the current limiting resistor, for the predetermined period, using the measured values ​​of the first voltage (Vcd) and the second voltage (Vcs) per unit time during a predetermined period (Ta) from when the switch is turned on until when resonance based on the equivalent inductor, the equivalent capacitor, and the equivalent resistance of the winding, which are stored in the storage unit, and the value of the equivalent capacitor,The value of at least one of the equivalent inductor and the equivalent resistance is calculated for each unit time.

[0012] [2] In the test apparatus described in [1] above, when the value of the equivalent inductor is Ld, the value of the equivalent capacitor is Cd, the value of the equivalent resistance is Rd, the value of the impulse voltage application capacitor is Cs, the value of the current limiting resistor is Rs, the first voltage is Vcd, the second voltage is Vcs, and time is t, an equation for the transient response of the first voltage may be expressed by equation (9) described later, and an equation for the transient response of the second voltage may be expressed by equation (10) described later.

[0013] [3] In the test device described in [1] or [2] above, the parameter calculation unit may calculate a value of the equivalent capacitor based on a measurement value of the first voltage and a measurement value of the second voltage during a first period (Tb) during which the current flowing through the equivalent inductor can be considered to be zero during the period during which the first voltage is rising immediately after the switch is turned on, and store the value in the memory unit.

[0014] [4] In the test apparatus described in [3] above, the parameter calculation unit may calculate the value of the equivalent capacitor based on a relational expression between the change in charge of the equivalent capacitor per unit time (h) (Qd) and the change in the first voltage per unit time (Vd), which is represented by the measured value of the first voltage and the measured value of the second voltage per unit time (h).

[0015] [5] In the test apparatus described in [4] above, when the measurement value of the second voltage at time a in the first period is Vcs|t=a, the measurement value of the first voltage at the time a is Vcd|t=a, the measurement value of the second voltage at time a+h which is earlier than the time a by the unit time h is Vcs|t=a+h, the measurement value of the first voltage at the time a+h is Vcd|t=a+h, the value of the current limiting resistor is Rs, and the value of the equivalent capacitor is Cd, the parameter calculation unit may calculate the value of the equivalent capacitor for each unit time based on the following equation (8).

[0016] [6] In the test apparatus described in any one of [3] to [5] above, the measurement unit may sample the first voltage and the second voltage every unit time (h), and the parameter calculation unit may acquire sampling data including the measurement values ​​of the first voltage and the measurement values ​​of the second voltage sampled by the measurement unit, and calculate the value of the equivalent capacitor for each data pair, each set consisting of the sampling data of two adjacent sampling points.

[0017] [7] In the test device described in any of [3] to [6] above, the first period (Tb) may be a period during which the first voltage is rising, excluding a predetermined period (Tx1) immediately after the switch is turned on and a predetermined period (Tx2) immediately before the first voltage reaches its maximum value.

[0018] [8] In the test apparatus described in [7] above, the first period (Tb) may be the period from the time when the measured value of the first voltage becomes α(0≦α<100)% of the maximum value of the first voltage to the time when the measured value of the first voltage becomes β(α<β≦100)% of the maximum value of the first voltage.

[0019] [9] The test device described in any one of [1] to [8] above may further include a waveform generation unit (6) that generates waveform data showing the temporal change in value of at least one of the equivalent capacitor, the equivalent inductor, and the equivalent resistance calculated by the parameter calculation unit, and a display unit (7) that displays a waveform based on the waveform data.

[0020]

[10] In the test device described in [9] above, the display unit may display a waveform indicating a change over time in the reciprocal (1 / Ld) of the value of the equivalent inductor.

[0021]

[11] In the test apparatus described in [9] or

[10] above, the display unit may display a waveform showing the temporal change in the value (Rd / Ld) obtained by dividing the value of the equivalent resistance by the value of the equivalent inductor.

[0022]

[12] A method according to a representative embodiment of the present invention is a testing method using a testing device (1) including a first external terminal (T1) to which one terminal of a winding (11) under test is connected, a second external terminal (T2) to which the other terminal of the winding is connected, an impulse voltage application capacitor (Cs) having one end connected to the second external terminal, a switch (SW) connected between the other end of the impulse voltage application capacitor and the first external terminal, and a current limiting resistor (Rs) connected in series with the switch between the other end of the impulse voltage application capacitor and the first external terminal. The test method includes a first step (S4) of turning on the switch, a second step (S5) of measuring a first voltage (Vcd) between the first external terminal and the second external terminal and a second voltage (Vcs) across the impulse voltage application capacitor, and a third step (S6) of calculating, based on the measured value of the first voltage and the measured value of the second voltage measured in the second step, a change over time in the value of at least one of an equivalent inductor (Ld) connected between the first external terminal and the second external terminal, an equivalent capacitor (Cd) connected between the first external terminal and the second external terminal, and an equivalent resistance (Rd) connected in series with the equivalent inductor between the first external terminal and the second external terminal. The third step includes steps (S7, S8), and the third step calculates the value per unit time of at least one of the equivalent inductor and the equivalent resistance by performing regression analysis based on an equation for the transient response of the first voltage and an equation for the transient response of the second voltage in an equivalent circuit formed by the equivalent inductor, the equivalent capacitor, and the equivalent resistance of the winding, the impulse voltage application capacitor, and the current limiting resistor for the predetermined period, using measured values ​​of the first voltage and the second voltage per unit time during a predetermined period from when the switch is turned on until resonance based on the equivalent inductor, the equivalent capacitor, and the equivalent resistance of the winding starts, and the value of the equivalent capacitor stored in the test device.

[0023] 2. Specific examples of embodiments Specific examples of embodiments of the present invention will be described below with reference to the drawings.

[0024] FIG. 1 is a diagram showing the configuration of a test device 1 according to an embodiment of the present invention. 1 is an apparatus for measuring the characteristics of windings (coils) that constitute electrical equipment such as rotating machines, such as electric motors and generators, and transformers. For example, the test apparatus 1 is an impulse winding test apparatus that calculates the values ​​of inductors, capacitors, and resistors, which are parameters related to the windings under test, based on the change in voltage when an impulse voltage is applied to the windings under test.

[0025] As shown in FIG. 1, the test device 1 has external terminals T1 and T2, an impulse voltage generating circuit 2, an instruction input unit 3, a measurement unit 4, a parameter calculation unit 5, a waveform generation unit 6, a display unit 7, and a storage unit 8.

[0026] The external terminals T1 and T2 are terminals for connecting the winding 11 as a device under test (DUT). For example, one terminal of the winding 11 is connected to the external terminal T1, and the other terminal of the winding 11 is connected to the external terminal T2.

[0027] The impulse voltage generating circuit 2 is a circuit for applying a desired impulse voltage to the test target winding 11 connected between external terminals T1 and T2. The impulse voltage generating circuit 2 includes, for example, an impulse voltage application capacitor Cs, a switch SW, a current limiting resistor Rs, and a rectifying element D.

[0028] The impulse voltage application capacitor Cs is a capacitor that stores an electric charge for generating an impulse voltage E. One end of the impulse voltage application capacitor Cs is connected to the external terminal T2.

[0029] The switch SW is an element for switching whether or not to output the impulse voltage E. The switch SW is realized by a semiconductor element such as a power transistor or a thyristor. The switch SW is connected between the other end of the impulse voltage application capacitor Cs and the external terminal T1.

[0030] The current limiting resistor Rs is an element for limiting the current that flows from the external terminal T1 to the test target winding 11 when the impulse voltage application capacitor Cs is discharged. The current limiting resistor Rs is connected in series with the switch SW between the other end of the impulse voltage application capacitor Cs and the external terminal T1.

[0031] The rectifying element D is an element that passes current from the impulse voltage application capacitor Cs side to the external terminal T1 side and blocks current from the external terminal T1 side to the impulse voltage application capacitor Cs side. The rectifying element D is, for example, a diode. In the following description, the rectifying element D is also referred to as a "reverse current prevention diode D."

[0032] The blocking diode D is connected in series with the switch SW and the current limiting resistor Rs between the other end of the impulse voltage application capacitor Cs and the external terminal T1. For example, the anode electrode of the blocking diode D is connected to one end of the current limiting resistor Rs, and the cathode electrode of the blocking diode D is connected to the external terminal T1.

[0033] In response to an instruction from the instruction input unit 3, the impulse voltage generating circuit 2 outputs an impulse voltage E between one end of the current limiting resistor Rs and the external terminal T2 via the switch SW. For example, first, the impulse voltage generation circuit 2 charges the impulse voltage application capacitor Cs with a DC power supply (not shown) so that the voltage of the impulse voltage application capacitor Cs becomes the impulse voltage E. Next, the impulse voltage generation circuit 2 turns on the switch SW in response to an instruction from the instruction input unit 3. As a result, the charge stored in the impulse voltage application capacitor Cs is discharged through the current limiting resistor Rs and the backflow prevention diode D, and a voltage Vcd is generated between the external terminals T1 and T2.

[0034] The instruction input unit 3 is a functional unit that receives instructions for the test apparatus 1. The instruction input unit 3 is realized by, for example, an input interface device such as an operation button or a touch panel that receives user operations on the test apparatus 1, and program processing by a CPU. When the user inputs test conditions such as the value of the impulse voltage E and the sampling frequency of the measuring unit 4 described below, the instruction input unit 3 stores these input values ​​in the memory unit 8, thereby setting the test conditions in the test apparatus 1. Furthermore, the instruction input unit 3 turns on the switch SW of the impulse voltage generating circuit 2 in response to the user's input of an instruction to start a test.

[0035] The measurement unit 4 is a functional unit that measures physical quantities such as voltage when a voltage is applied to the winding 11 connected between the external terminals T1 and T2. Specifically, the measurement unit 4 measures the voltage Vcd (first voltage) between the external terminals T1 and T2 and the voltage Vcs (second voltage) across the impulse voltage application capacitor Cs. For example, the measurement unit 4 measures the voltage Vcs between the external terminal T2 and a node connecting the switch SW and the current limiting resistor Rs.

[0036] For example, the measurement unit 4 includes a known voltage detection circuit and current detection circuit, and an A / D conversion circuit that samples the voltage and current detected by the voltage detection circuit and current detection circuit at a predetermined sampling period and converts them into digital signals.

[0037] The measurement unit 4 stores measurement value information 81 including the measurement values ​​of the voltage Vcd and the voltage Vcs in the storage unit 8. For example, the measurement unit 4 samples the voltage Vcd and the voltage Vcs at a predetermined sampling period to obtain time-series data of the measurement values ​​(sampling data) of the voltage Vcd and the voltage Vcs, and stores the data in the storage unit 8 as measurement value information 81.

[0038] The method for measuring the voltage Vcs by the measurement unit 4 is not limited to a method in which the voltage between the external terminal T2 and the node connecting the switch SW and the current-limiting resistor Rs is directly measured using a voltage detection circuit. For example, the measurement unit 4 may detect the current flowing through the external terminal T1, i.e., the current Irs flowing through the current-limiting resistor Rs, using a current detection circuit, and calculate the measured value of the voltage Vcs based on the measured value of the current Irs and the measured value of the voltage Vcd (Vcs = Vcd + Rs × Irs). Alternatively, the measurement unit 4 may measure the voltage Vrs across the current-limiting resistor Rs using a voltage detection circuit, and calculate the measured value of the voltage Vcs based on the measured value of the voltage Vrs and the measured value of the voltage Vcd (Vcs = Vcd + Vrs).

[0039] The parameter calculation unit 5 is a functional unit that calculates the values ​​of the equivalent capacitor Cd, equivalent inductor Ld, and equivalent resistance Rd as parameters related to the test target winding 11. The waveform generation unit 6 is a functional unit that generates data of various waveforms that indicate characteristics such as voltage and current related to the test target winding 11. The detailed functions of the parameter calculation unit 5 and the waveform generation unit 6 will be described later.

[0040] The storage unit 8 is a functional unit for storing programs and various parameters for the test device 1 to function as an impulse winding test device, test results of the winding 11 to be tested, and the like.

[0041] Here, the parameter calculation unit 5, waveform generation unit 6, and storage unit 8 are realized, for example, by a program processing device. The program processing device is, for example, a microcontroller having a configuration in which a processor such as a CPU, various storage devices such as RAM and ROM, and peripheral circuits such as a counter (timer), an A / D conversion circuit, a D / A conversion circuit, a clock generation circuit, and an input / output I / F circuit are connected to each other via a bus or a dedicated line. For example, in the program processing device, the CPU executes various arithmetic processes in accordance with programs stored in memory, stores the results of the arithmetic processes in a storage device such as RAM, and controls the peripheral circuits such as the counter and the input / output interface circuit, thereby realizing the parameter calculation unit 5, waveform generation unit 6, and storage unit 8 described above.

[0042] The display unit 7 is a functional unit that displays information for setting test conditions, information on test results, etc. The display unit 7 is realized by, for example, a display device such as a liquid crystal display.

[0043] As described above, the test apparatus 1 analyzes the characteristics of the test target winding 11 and calculates parameters related to the winding 11. Specifically, the test apparatus 1 calculates the values ​​of the equivalent inductor Ld, the equivalent capacitor Cd, and the equivalent resistance Rd, which are parameters related to the winding 11, based on the transient response characteristics of the voltage Vcd between the external terminals T1 and T2 and the voltage Vcs across the impulse voltage application capacitor Cs when an impulse voltage E is applied to the winding 11 connected between the external terminals T1 and T2.

[0044] FIG. 2 is a diagram showing an equivalent circuit when test device 1 is connected to winding 11 under test. FIG. 3 is a diagram showing an example of the characteristics of the voltage Vcd across the winding 11 when an impulse voltage is applied between the external terminals T1 and T2 with the winding 11 connected to the test apparatus 1. In FIG.

[0045] 3, the horizontal axis represents time (μs) and the vertical axis represents voltage (V). The waveform indicated by reference numeral 110 shows the change over time in voltage Vcd after the impulse voltage application capacitor Cs is charged so that the impulse voltage E becomes 1000 V and the switch SW is turned on.

[0046] 2, the winding 11 is equivalently represented by an equivalent inductor Ld, an equivalent capacitor Cd, and an equivalent resistance Rd. Specifically, when the winding 11 side is viewed from the external terminals T1 and T2, the circuit is equivalently represented by an equivalent inductor Ld connected between the external terminals T1 and T2, an equivalent capacitor Cd connected between the external terminals T1 and T2, and an equivalent resistance Rd connected in series with the equivalent inductor Ld between the external terminals T1 and T2.

[0047] As shown in FIG. 3, when the switch SW of the impulse voltage generating circuit 2 is turned on, the charge in the impulse voltage application capacitor Cs moves through the current limiting resistor Rs and the backflow prevention diode D, and the equivalent capacitor Cd of the winding 11 is charged.

[0048] When switch SW is turned on at time t=0s, immediately after switch SW is turned on, due to the properties of equivalent inductor Ld, current does not flow through the equivalent inductor Ld of winding 11, but instead flows into equivalent capacitor Cd. As a result, voltage Vcd between external terminals T1 and T2 rises to about 1000 V, which is the charging voltage (impulse voltage E) of impulse voltage application capacitor Cs. However, the degree to which voltage Vcd rises varies depending on the properties of winding 11.

[0049] After that, current begins to flow through the equivalent inductor Ld via the equivalent resistance Rd, causing the voltage Vcd to drop. When the voltage Vcd drops to approximately -1000 V, the reverse current prevention diode D electrically isolates the impulse voltage generating circuit 2 from the circuit on the winding 11 side. As a result, around time t = 10 μs in Figure 3, the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd of the winding 11 begin to resonate, causing the voltage Vcd to undergo damped oscillation. After that, the voltage Vcd finally reaches 0 V. However, the extent and time at which the voltage Vcd drops varies greatly depending on the characteristics of the winding 11.

[0050] As shown in FIG. 3, the test apparatus 1 according to the first embodiment defines an analysis period as a predetermined period Ta from when the switch SW is turned on until resonance by the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd on the winding side begins, and calculates the change over time in the value of at least one of the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd based on the measured values ​​of the voltages Vcd and Vcs during the analysis period Ta and equations for the transient responses of the voltages Vcd and Vcs based on the equivalent circuit during the analysis period Ta.

[0051] Conventional impulse winding testing machines (measurement devices) use equations and measured values ​​of the voltage Vcd at resonance due to the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd of the winding 11, and are therefore only able to calculate the multiplication value of each parameter, such as the LC value and RC value. In contrast, the test device 1 according to this embodiment performs calculations based on equations for the transient response of the voltages Vcd and Vcs in the equivalent circuit before resonance begins. This makes it possible to individually calculate the changes over time in the values ​​of the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd, as will be described later, and also enables the analysis to be completed in a shorter time. A specific method for calculating each parameter related to the winding 11 using the test device 1 will be described below.

[0052] (1) Calculation method for equivalent capacitor Cd First, a method for calculating the equivalent capacitance Cd of the winding 11 will be described. The test device 1 according to this embodiment calculates the value of the equivalent capacitor Cd per unit time based on the measured value of the voltage Vcd during the period in which the current flowing through the equivalent inductor Ld is negligible, during the period in which the voltage Vcd is rising immediately after the switch SW is turned on, and stores the value in the memory unit 8 as analysis result information 83.

[0053] FIG. 4 is a diagram for explaining a method for calculating the equivalent capacitance Cd of the winding 11. In FIG. 4, the waveform labeled 110A is an enlarged version of the portion of range A in the waveform 110 of the voltage Vcd shown in FIG.

[0054] As described above, when the switch SW is turned on while the impulse voltage application capacitor Cs is charged, immediately after the switch SW is turned on, the voltage Vcd rises from 0 V to a maximum value Vmax (e.g., 980 V) as shown by reference numeral 110A in FIG. 4.

[0055] Here, if the current flowing through the current limiting resistor Rs of the impulse voltage generating circuit 2 to the external terminal T1 is Irs, the current flowing through the equivalent capacitor Cd of the winding 11 is Icd, and the current flowing through the equivalent inductor Ld through the equivalent resistance Rd of the winding 11 is Ild, then Irs = Icd + Ild.

[0056] As described above, immediately after switch SW is turned on, no current flows through equivalent inductor Ld of winding 11, so Ild can be considered to be 0. If Ild is considered to be 0, current Icd flowing through equivalent capacitor Cd can be considered to be equal to current Irs flowing from current-limiting resistor Rs to external terminal T1, and equivalent inductor Ld and equivalent resistance Rd can be ignored in the equivalent circuit shown in FIG.

[0057] Therefore, the parameter calculation unit 5 calculates the value of the equivalent capacitor Cd based on the measured values ​​of the voltage Vcd and the voltage Vcs during the analysis period Tb during which the current Ild flowing through the equivalent inductor Ld can be considered to be zero during the period when the voltage Vcd is rising immediately after the switch SW is turned on.

[0058] Here, the analysis period Tb for the equivalent capacitor Cd is preferably set to a period during which the voltage Vcd is rising, excluding a predetermined period Tx1 immediately after the switch SW is turned on and a predetermined period Tx2 immediately before the voltage Vcd reaches its maximum value Vmax, as shown in FIG. 4.

[0059] For example, the analysis period Tb is the period from time tα when the measured value of voltage Vcd is α (0≦α<100)% of the maximum value Vmax of voltage Vcd to time tβ when the measured value of voltage Vcd is β (α<β≦100)% of the maximum value Vmax of voltage Vcd, where α=25% and β=75%, for example.

[0060] Period Tx1 includes a period in which it is unclear whether switch SW has been turned on, and is a period in which, immediately after switch SW is turned on, ringing due to parasitic capacitance and parasitic inductance and waveform distortion due to the influence of a control circuit (not shown) are likely to occur. Period Tx2, on the other hand, is a period in which, as with period Tx1, the precondition Ild = 0 is no longer met because current gradually begins to flow through equivalent inductor Ld of winding 11, and is also a period in which ringing due to parasitic capacitance and parasitic inductance is likely to occur.

[0061] Therefore, by using the period Tb excluding such periods Tx1 and Tx2 as the analysis period for the equivalent capacitor Cd, it is possible to reduce the influence of the above-mentioned ringing and the like on the analysis results for the equivalent capacitor Cd.

[0062] The method for calculating the equivalent capacitance Cd will be described in detail below. If the voltage Vcs at time t=a in the analysis period Tb is Vcs|t=a and the voltage Vcd at time t=a is Vcd|t=a, then the current Icd at time t=a is expressed by the following equation (1) since Irs=Icd.

[0063]

number

[0064] If the voltage Vcs at time t=a+h (h is unit time) during the analysis period Tb is Vcs|t=a+h and the voltage Vcd at time t=a+h is Vcd|t=a+h, then since Irs=Icd, the current Icd at time t=a+h can be expressed by the following equation (2).

[0065] Here, the unit time h is, for example, a time corresponding to the sampling period of the A / D conversion circuit that constitutes the measuring unit 4 described above.

[0066]

number

[0067] Here, the average value Iave of the current Icd during the period from time t=a to time t=a+h is expressed by the following equation (3).

[0068]

number

[0069] The amount of change Qd in charge due to the current flowing into the equivalent capacitor Cd of the winding 11 during the period from time t=a to time t=a+h is expressed by the following equation (4) using the average value Iave of the current Icd.

[0070]

number

[0071] Furthermore, the amount of change Vd in the voltage across the equivalent capacitor Cd during the period from time t=a to time t=a+h is expressed by the following equation (5).

[0072]

number

[0073] The relationship between the amount of change Vd in voltage and the amount of change Qd in charge in the equivalent capacitor Cd is expressed by the following equation (6).

[0074]

number

[0075] Here, by substituting the formulas (4) and (5) into the formula (6) above, the following formula (7) is obtained.

[0076]

number

[0077] As can be seen from the above equations (6) and (7), the value of the equivalent capacitor Cd is expressed by the amount of change in the charge of the equivalent capacitor Cd and the amount of change in the voltage Vcd of the equivalent capacitor Cd per unit time h.

[0078] Here, by substituting the above equations (1) to (3) into the above equation (7) and solving for Cd, the equivalent capacitor Cd can be expressed by the following equation (8).

[0079]

number

[0080] As can be seen from the above equation (8), the equivalent capacitor Cd can be expressed by the voltages Vcd and Vcs at two sampling points (times) in the analysis period Tb and the current limiting resistor Rs.

[0081] Therefore, the parameter calculation unit 5 calculates the value of the equivalent capacitor Cd per unit time based on the relational expression (the above-mentioned expression (8)) between the change Qd in the charge of the equivalent capacitor Cd and the change Vd in the voltage Vcd per unit time h, which is represented by the measured value of the voltage Vcd and the measured value of the voltage Vcs per unit time h.

[0082] Specifically, the parameter calculation unit 5 calculates the value of the equivalent capacitor Cd by substituting the measurement value Vcs|t=a of the voltage Vcs and the measurement value Vcd|t=a of the Vcd at time t=a of the analysis period Tb, the measurement value Vcs|t=a+h of the voltage Vcs and the measurement value Vcd|t=a+h of the Vcd at time t=a+h of the analysis period Tb, and the known value of the current limiting resistance Rs into the above equation (8).

[0083] The parameter calculation unit 5 calculates multiple values ​​of the equivalent capacitor Cd using multiple sampling data of the voltages Vcd and Vcs during the analysis period Tb. Specifically, the parameter calculation unit 5 acquires sampling data including the measurement values ​​of the voltages Vcd and Vcs sampled by the measurement unit 4, and calculates the value of the equivalent capacitor Cd for each data pair, each set consisting of sampling data from two adjacent sampling points.

[0084] For example, suppose that the measurement unit 4 samples the voltages Vcs and Vcd every unit time h during the analysis period Tb from time tα to time tβ shown in Fig. 4, and acquires 21 pairs of sampling data. In this case, the parameter calculation unit 5 calculates 20 pairs of values ​​of the equivalent capacitor Cd by substituting a total of 20 pairs of data, each pair consisting of sampling data from two adjacent sampling points, into the above equation (8). This makes it possible to know the change over time in the equivalent capacitor Cd during the analysis period Tb.

[0085] The parameter calculation unit 5 may calculate a value (fixed value) of one equivalent capacitor Cd by calculating the average or median of the multiple (20 in the above example) equivalent capacitor Cd values ​​calculated for each of the above-mentioned data pairs. Here, the method for calculating the average value of the equivalent capacitor Cd is not particularly limited, and various methods such as the arithmetic mean or trimmed mean can be used.

[0086] The parameter calculation unit 5 stores the time-series data of the equivalent capacitor Cd calculated by the above-mentioned method, the average value of the equivalent capacitor Cd, and the like in the storage unit 8 as analysis result information 83.

[0087] 5 to 7 are diagrams showing examples of the analysis results of the equivalent capacitor Cd of the winding 11 by the test device 1. FIG.

[0088] 5 to 7 show a waveform 120 of the voltage Vcd, a waveform 121 of the current Icd, and a waveform 122 of the value of the equivalent capacitor Cd when the impulse voltage application capacitor Cs is charged to 100 V and then the switch SW is turned on to apply a voltage to the winding 11 under test.

[0089] After the switch SW is turned on at time t=0, during an analysis period Tb in which the current Ild flowing through the equivalent inductor Ld of the winding 11 can be considered to be 0, the voltage Vcd of the equivalent capacitor Cd increases linearly as shown in Fig. 5, while the current Icd flowing through the equivalent capacitor Cd decreases while oscillating as shown in Fig. 6. At this time, the value of the equivalent capacitor Cd during the analysis period Tb fluctuates but is more stable than in other periods, as shown in Fig. 7.

[0090] (2) Calculation method for equivalent inductor Ld and equivalent resistance Rd Next, a method for calculating the equivalent inductor Ld and the equivalent resistance Rd of the winding 11 will be described.

[0091] The parameter calculation unit 5 uses the measurement values ​​(measurement value information 81) of the voltages Vcd and Vcs per unit time during a predetermined period from when the switch SW is turned on until resonance based on the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd of the winding 11 starts, which are stored in the storage unit 8, and the value of the equivalent capacitor Cd (analysis result information 83) stored in the storage unit 8, to calculate at least one value per unit time of the equivalent inductor Ld and the equivalent resistance Rd by performing regression analysis based on an equation for the transient response of the voltage Vcd and an equation for the transient response of the voltage Vcs, which are based on an equivalent circuit formed by the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd of the winding 11, the impulse voltage application capacitor Cs, and the current limiting resistor Rs, during the predetermined period.

[0092] The parameter calculation unit 5 determines the above-mentioned predetermined period, i.e., the analysis period for the equivalent inductor Ld and the equivalent resistance Rd, as the period Ta from when the switch SW is turned on to when resonance based on the equivalent inductor Ld, the equivalent capacitor Cd, and the equivalent resistance Rd of the winding 11 starts (see FIG. 3).

[0093] More preferably, the parameter calculation unit 5 determines the analysis period as a period from a predetermined time after the voltage Vcd reaches its maximum value Vmax after the switch SW is turned on to a predetermined time before the voltage Vcd reaches its minimum value. For example, as shown in Fig. 3, the period Tc for analyzing the equivalent inductor Ld and the equivalent resistance Rd is determined as a period from a time t1 when the voltage Vcd reaches 90% of its positive peak value to a time t2 when the voltage Vcd reaches 90% of its negative peak value.

[0094] By excluding the period up to time t1 from the analysis period, the period in which voltage Vcd rises immediately after switch SW is turned on is excluded, thereby reducing the impact of ringing of voltage Vcd due to parasitic capacitance and parasitic inductance on the analysis results of equivalent inductor Ld and equivalent resistance Rd. Similarly, by excluding the period from time t2 to the point at which rectifier D cuts off the current from the analysis period, the impact on the analysis results of equivalent inductor Ld and equivalent resistance Rd can be reduced.

[0095] The parameter calculation unit 5 calculates the temporal changes in the values ​​of the equivalent inductor Ld and the equivalent resistance Rd by performing a regression analysis based on the equations of the transient response of the voltages Vcd and Vcs using the measured values ​​of the voltages Vcd and Vcs during the analysis period Tc. The method for calculating the equivalent inductor Ld and the equivalent resistance Rd will be described in detail below.

[0096] 2, when the time elapsed since the switch SW was turned on is t, the equation for the transient response of the voltage Vcd during the analysis period Tc is expressed by the following equation (9): Furthermore, the equation for the transient response of the voltage Vcs during the analysis period Tc is expressed by the following equation (10):

[0097]

number

[0098]

number

[0099] The following formulas (11) and (12) can be derived from the above formulas (9) and (10). The following formula (11) is a formula obtained by dividing the above formula (9) into a term including Ld, a term including Rd, and other terms. The following formula (12) is a formula obtained by subtracting the above formula (9) from the above formula (10) into a term including Ld, a term including Rd, and other terms.

[0100]

number

[0101]

number

[0102] Here, as shown in the following equations (13) to (18), if some of the terms in the above equations (11) and (12) are replaced with a, b, c, d, e, and f, respectively, the above equations (11) and (12) can be expressed by the following equations (19) and (20), respectively.

[0103]

number

[0104]

number

[0105]

number

[0106]

number

[0107]

number

[0108]

number

[0109]

number

[0110]

number

[0111] Here, by solving the above equations (19) and (20) for Ld and Rd, respectively, the equivalent inductor Ld and the equivalent resistance Rd can be expressed by the following equations (21) and (22), respectively.

[0112]

number

[0113]

number

[0114] As can be seen from the above equations (21) and (22), the values ​​of a to f can be found at any time (sampling point) of the waveforms of the voltages Vcd and Vcs, and therefore it is possible to calculate the values ​​of the equivalent inductor Ld and the equivalent resistance Rd at any time (sampling point) of the waveforms of the voltages Vcd and Vcs. Specifically, the parameter calculation unit 5 calculates the values ​​of the equivalent inductor Ld and the equivalent resistance Rd using the following method.

[0115] The parameter calculation unit 5 calculates a to f based on the measured values ​​of the voltages Vcd and Vcs and the above equations (13) to (18), and calculates the values ​​of the equivalent inductor Ld and the equivalent resistance Rd based on the calculated a to f and equations (21) and (22). For example, first, the parameter calculation unit 5 determines an analysis period Tc. For example, as shown in Fig. 3, the parameter calculation unit 5 detects a sampling point (time) t1 at which the voltage Vcd reaches 90% of its positive peak value (maximum value Vmax) and a sampling point (time) t2 at which the voltage Vcd reaches 90% of its negative peak value (minimum value Vmin). The parameter calculation unit 5 determines the period between the sampling points t1 and t2 as the analysis period Tc, and sets the time when the switch SW is turned on as t=0.

[0116] Next, the parameter calculation unit 5 performs a known smoothing process on the time series data of the measured values ​​of the voltage Vcd and the voltage Vcs during the analysis period Tc. For example, the parameter calculation unit 5 calculates the moving averages of the time series data of the measured values ​​of the voltages Vcd and Vcs during the analysis period Tc, respectively, to obtain the smoothed measured values ​​of the voltages Vcd and Vcs.

[0117] Next, the parameter calculation unit 5 uses the measured values ​​of the smoothed voltages Vcd and Vcs to calculate TIFF0007796553000023.tif13170. For example, the parameter calculation unit 5 uses the measurement values ​​of Vcd and Vcs at two adjacent sampling points to calculate a value obtained by first differentiating Vcs with respect to time t, a value obtained by second differentiating Vcs with respect to time t, a value obtained by third differentiating Vcs with respect to time t, a value obtained by first differentiating Vcd with respect to time t, a value obtained by second differentiating Vcd with respect to time t, and a value obtained by third differentiating Vcd with respect to time t.

[0118] Here, the values ​​of the impulse voltage application capacitor Cs and the current limiting resistor Rs are known, and the value of the equivalent capacitor Cd of the winding 11 is estimated by the above-mentioned method and stored in the storage unit 8.

[0119] The parameter calculation unit 5 uses the values ​​of the impulse voltage application capacitor Cs, the current limiting resistor Rs, and the equivalent capacitor Cd stored in the storage unit 8, and the calculated TIFF0007796553000024.tif13170 into the above equations (13) to (18), thereby calculating a, b, c, d, e, and f at any time (sampling point).

[0120] Next, the parameter calculation unit 5 calculates the values ​​of the equivalent inductor Ld and the equivalent resistance Rd by substituting the calculated values ​​of a, b, c, d, e, and f into the above equations (21) and (22).

[0121] The parameter calculation unit 5 performs the above calculations for each sampling point (unit time) in the analysis period Tc to calculate the values ​​of the equivalent inductor Ld and the equivalent resistance Rd for each unit time (sampling point).The parameter calculation unit 5 stores the calculated values ​​of the equivalent inductor Ld and the equivalent resistance Rd for each unit time in the storage unit 8 as analysis result information 83. This makes it possible to calculate the temporal changes in the equivalent inductor Ld and the equivalent resistance Rd during the analysis period Tc.

[0122] Here, information required to calculate the equivalent capacitor Cd, the equivalent inductor Ld, and the equivalent resistance Rd may be stored in advance in the storage unit 8. For example, the information of the above formula (8), the above formulas (13) to (18), the above formula (21), and the above formula (22), the value of the current limiting resistor Rs, and the value of the impulse voltage application capacitor Cs may be stored in advance in the storage unit 8 as formula information 82. In addition, the value of the impulse voltage E set by the user at the start of the test is also stored in the storage unit 8 as formula information 82.

[0123] The parameter calculation unit 5 can calculate the values ​​of the equivalent capacitor Cd, equivalent inductor Ld, and equivalent resistance Rd of the winding 11 by reading out the mathematical formula information 82 and the measurement value information 81 stored in the memory unit 8 and performing the above-mentioned calculations.

[0124] 8 to 10 are diagrams showing an example of the analysis results of the equivalent inductor Ld and the equivalent resistance Rd of the winding 11 by the test apparatus 1 when no magnetic saturation occurs in the winding 11. FIG. 11 to 13 are diagrams showing an example of the analysis results of the equivalent inductor Ld and the equivalent resistance Rd of the winding 11 by the test device 1 when magnetic saturation occurs in the winding 11. FIG.

[0125] 8 to 10 show waveforms 210 of voltage Vcd, 211 of equivalent inductor Ld, and 212 of equivalent resistance Rd when impulse voltage application capacitor Cs is charged to 100 V, and then switch SW is turned on at time t=0 to apply voltage to winding 11 under test, and no magnetic saturation occurs in winding 11.

[0126] 11 to 13 show waveforms 220 of voltage Vcd, 221 of equivalent inductor Ld, and 222 of equivalent resistance Rd when magnetic saturation occurs in winding 11 by charging impulse voltage application capacitor Cs to 300 V and then turning on switch SW at time t=0 to apply voltage to winding 11 under test.

[0127] In Figures 8 to 13, the horizontal axis represents the number of samples (sampling points) taken by the measuring unit 4 per unit time h, i.e., the elapsed time. In Figures 8 and 11, the vertical axis represents voltage (V). In Figures 9 and 12, the vertical axis represents inductance (H). In Figures 10 and 13, the vertical axis represents resistance (Ω).

[0128] When magnetic saturation does not occur in winding 11, the value of equivalent inductor Ld is stable at approximately 1 mH, as shown in Figure 9. Furthermore, as shown in Figure 10, the value of equivalent resistance Rd varies, but averages approximately 43 Ω. Note that, in order to further reduce the variation in equivalent resistance Rd, other known smoothing processes may be performed instead of performing moving average processing on the time-series data of the measured values ​​of voltages Vcd and Vcs as described above.

[0129] 12 and 13, when magnetic saturation occurs in winding 11, the values ​​of equivalent inductor Ld and equivalent resistance Rd fluctuate more significantly than when magnetic saturation does not occur, and diverge at some sampling points. When magnetic saturation occurs in winding 11, the average value of equivalent inductor Ld is about one-tenth of when magnetic saturation does not occur, and the average value of equivalent resistance Rd is 20 to 30 Ω.

[0130] As mentioned above, when magnetic saturation occurs, the values ​​of the equivalent inductor Ld and the equivalent resistance Rd may diverge at some sampling points. Therefore, the waveforms of the equivalent inductor Ld and the equivalent resistance Rd may be expressed in a different format.

[0131] 14 and 15 are diagrams showing examples of waveforms in which the values ​​of the equivalent inductor Ld and the equivalent resistance Rd of the winding 11 measured by the test apparatus 1 are expressed in a different format.

[0132] Fig. 14 shows a waveform 230 indicating the temporal change in "1 / Ld," which is the reciprocal of the value of the equivalent inductor Ld. Fig. 15 shows a waveform 231 indicating the temporal change in "Rd / Ld," which is the value obtained by dividing the value of the equivalent resistance Rd by the value of the equivalent inductor Ld. In Fig. 14, the horizontal axis represents the sampling point (elapsed time) per unit time h by the measuring unit 4, and the vertical axis represents 1 / Ld [1 / H]. In Fig. 15, the horizontal axis represents the sampling point (elapsed time) per unit time h by the measuring unit 4, and the vertical axis represents Rd / Ld [Ω / H].

[0133] As shown in FIGS. 14 and 15, by expressing the equivalent inductor Ld and the equivalent resistance Rd using waveforms in different formats, the waveforms do not diverge even when magnetic saturation occurs, making it easier for the user to analyze the characteristics of the winding 11.

[0134] In addition to the function of individually calculating the values ​​of the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd for the winding 11 under test described above, the test apparatus 1 also has a waveform display function of displaying waveforms that show the temporal changes in the calculated equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd. The waveform display function will be described in detail below.

[0135] 1, the waveform generating unit 6 generates waveform data 84 indicating a change over time in the value of at least one of the equivalent capacitor Cd, the equivalent inductor Ld, and the equivalent resistance Rd calculated by the parameter calculating unit 5. For example, the waveform generating unit 6 generates waveform data 84 indicating a change over time in, for example, Vcd, Icd, Cd, Ld, and Rd based on the analysis result information 83 and the measurement value information 81 stored in the storage unit 8, and stores the waveform data 84 in the storage unit 8.

[0136] The display unit 7 displays a waveform based on the waveform data 84 generated by the waveform generating unit 6 on the screen.

[0137] FIG. 16 is a diagram showing an example of the display screen of the test device 1. As shown in FIG. As shown in FIG. 16, the test device 1 is provided with a display 70 as one means for realizing the function of the display unit 7. The test device 1 displays information for setting test conditions, information on test results, etc. on the screen of the display 70. For example, the display 70 is equipped with a touch panel, and some of the functions of the instruction input unit 3 are realized by the display 70. For example, the user can set test conditions, etc. by touching the screen of the display 70.

[0138] The test device 1 may also have various physical buttons as means for realizing some of the functions of the instruction input unit 3. For example, as shown in Fig. 16, the test device 1 may have a power button 30 for starting the test device 1, a start button 31 for starting a test, a stop button 32 for stopping a test, and the like.

[0139] For example, when a user operates the instruction input unit 3 to instruct display of the waveform of a specific physical quantity, the display unit 7 reads out waveform data 84 of the physical quantity specified by the user from the storage unit 8 and displays it on the display 70. For example, at least one of the waveforms 120-122, 210-212, 220-222, 230, and 231 shown in the above-mentioned FIGS. 5 to 15 is displayed on the display 70. Note that FIG. 16 shows a case where a waveform 300 of the voltage Vcd is displayed on the display 70.

[0140] The display unit 7 may simultaneously display a plurality of waveforms. For example, the waveforms of the equivalent capacitor Cd, the equivalent inductor Ld, and the equivalent resistance Rd may be displayed side by side in the vertical or horizontal direction of the screen of the display 70.

[0141] Furthermore, as described above, the display unit 7 may display the measured waveform on the display 70 in response to a user's operation of the instruction input unit 3, or may display the measured waveform on the display 70 after calculating the parameters (Ld, Cd, Rd) of the winding 11 under test, regardless of whether or not there is an instruction from the user.

[0142] Next, the flow of a method for analyzing the winding 11 under test using the test device 1 will be described.

[0143] FIG. 17 is a flowchart showing the flow of a method for analyzing winding 11 using test device 1 according to this embodiment.

[0144] For example, after the user operates the power button 30 to start up the test device 1, the user touches the display 70 serving as the instruction input unit 3 to set test conditions and the like in the test device 1 (step S1). For example, the user sets the value of the impulse voltage E, the sampling period (sampling frequency) for measuring the voltages Vcd and Vcs, and the like in the test device 1.

[0145] In the initial state after the test device 1 is started, the switch SW of the impulse voltage generating circuit 2 is in the OFF state.

[0146] Next, the user connects the winding 11 to be tested between the external terminals T1 and T2 of the test device 1 (step S2). Note that the winding 11 may be connected to the test device 1 before step S1.

[0147] Next, the test device 1 determines whether or not a command to execute a test has been input by the user (step S3). For example, if the start button 31 has not been operated by the user (step S3: NO), the test device 1 waits until the start button 31 is operated.

[0148] When the start button 31 is operated (step S3: YES), the test apparatus 1 outputs an impulse voltage E between one end of the current limiting resistor Rs and the external terminal T2 via the switch SW (step S4). Specifically, in response to an instruction from the instruction input unit 3, the impulse voltage generation circuit 2 charges the impulse voltage application capacitor Cs with a DC power supply (not shown) so that the voltage of the impulse voltage application capacitor becomes the impulse voltage E set in step S1. Next, the impulse voltage generation circuit 2 turns on the switch SW. As a result, a voltage is applied between the external terminals T1 and T2.

[0149] Furthermore, the test apparatus 1 starts measuring the voltage Vcd between the external terminals T1 and T2 and the voltage Vcs of the impulse voltage application capacitor Cs (step S5), for example, simultaneously with step S4. Specifically, as described above, the measurement unit 4 measures the voltage Vcd between the external terminals T1 and T2 and the voltage Vcs across the impulse voltage application capacitor Cs based on the sampling period set in step S1, and stores the time-series data of the measurement values ​​of the voltages Vcd and Vcs in the storage unit 8 as measurement value information 81.

[0150] As described above, instead of measuring the voltage Vcs of the impulse voltage application capacitor Cs, the measurement unit 4 may measure the current Irs flowing through the current limiting resistor Rs or the voltage Vrs of the current limiting resistor Rs, and calculate the measurement value of the voltage Vcs based on the measurement value.

[0151] Next, the parameter calculation unit 5 determines, using the above-described method, an analysis period Tb for analyzing the equivalent capacitor Cd of the winding 11 and an analysis period Tc for analyzing the values ​​of the equivalent inductor Ld and the equivalent resistance Rd (step S6).

[0152] Next, the parameter calculation unit 5 calculates the value of the equivalent capacitor Cd for the winding 11 using the measurement values ​​of the voltages Vcd and Vcs during the analysis period Tb set in step S6 and the formula information 82 stored in the memory unit 8 using the above-mentioned method (step S7).

[0153] Next, the parameter calculation unit 5 uses the measured values ​​of the voltages Vcd and Vcs during the analysis period Tc set in step S6 and the formula information 82 stored in the memory unit 8 to calculate the value of the equivalent inductor Ld and the value of the equivalent resistance Rd for the winding 11 using the method described above (step S8).

[0154] Next, the waveform generating unit 6 generates waveform data 84 using the above-described method based on the measured values ​​of the voltages Vcd and Vcs acquired in step S5 and the values ​​of the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd for the winding 11 calculated in steps S7 and S8 (step S9).

[0155] Next, the display unit 7 displays a waveform on the screen of the display 70 of the test device 1 based on the waveform data 84 generated in step S9 (step S10).

[0156] The waveform data generation process (step S9) and waveform display process (step S10) described above may be performed, for example, only when the user operates the test device 1 and the instruction input unit 3 receives an instruction to display the waveform from the user.

[0157] As described above, the test apparatus 1 according to this embodiment has a parameter calculation unit 5 that calculates the change over time in the value of at least one of the equivalent inductor Ld, the equivalent capacitor Cd, and the equivalent resistance Rd when the winding 11 under test, which is connected between the external terminals T1 and T2, is equivalently represented by an equivalent inductor Ld connected between the external terminals T1 and T2, an equivalent capacitor Cd connected between the external terminals T1 and T2, and an equivalent resistance Rd connected in series with the equivalent inductor Ld between the external terminals T1 and T2, based on the measured values ​​of the voltage Vcd between the external terminals T1 and T2 and the voltage Vcs across the impulse voltage application capacitor Cs measured by the measurement unit 4.

[0158] Specifically, the parameter calculation unit 5 uses measured values ​​of the voltage Vcd and the voltage Vcs during the period (analysis period Tc) from when the switch SW is turned on until resonance based on the equivalent inductor Ld, the equivalent capacitor Cd, and the equivalent resistance Rd of the winding 11 starts, to perform regression analysis based on an equation for the transient response of the voltage Vcd and the voltage Vcs in an equivalent circuit formed by the equivalent inductor Ld, the equivalent capacitor Cd, and the equivalent resistance Rd of the winding 11, the impulse voltage application capacitor Cs, and the current limiting resistor Rs for the winding 11 during the analysis period Tc, thereby calculating at least one value per unit time of the value of the equivalent inductor Ld and the value of the equivalent resistance Rd of the winding 11.

[0159] The test apparatus 1 having such a configuration measures not only the transient response of the voltage Vcd as in conventional test apparatuses, but also the transient response of the voltage Vcs across the impulse voltage application capacitor Cs to calculate the values ​​of the equivalent inductor Ld and the equivalent resistance Rd, so that the values ​​of the equivalent inductor Ld and the equivalent resistance Rd can be calculated for each sampling point (unit time) of measurement by the measurement unit 4. In other words, the test apparatus 1 can calculate the changes over time in the values ​​of the equivalent inductor Ld and the equivalent resistance Rd. This allows the user to analyze changes in the characteristics of the winding 11 under test when magnetic saturation occurs in the winding 11.

[0160] In the test apparatus 1, the equation for the transient response of the voltage Vcd as the first voltage is expressed by the above equation (9), and the equation for the transient response of the voltage Vcs as the second voltage is expressed by the above equation (10). This makes it possible to more accurately and easily calculate the values ​​of the equivalent inductor Ld and the equivalent resistance Rd per unit time.

[0161] In addition, the parameter calculation unit 5 calculates the value of the equivalent capacitor Cd based on the measured values ​​of the voltage Vcd and the voltage Vcs during the first period (analysis period Tb) during which the current flowing through the equivalent inductor Ld can be considered to be zero during the period during which the voltage Vcd rises after the switch SW is turned on. According to this, the value of the equivalent capacitor Cd can be easily calculated using a simple equation based on an equivalent circuit that ignores the equivalent inductor Ld and the equivalent resistance Rd.

[0162] Furthermore, the parameter calculation unit 5 calculates the value of the equivalent capacitor Cd based on a relational expression between the amount of change in the charge of the equivalent capacitor Cd over unit time h and the amount of change in the voltage Vcd over unit time h, which is expressed by the measured value of the voltage Vcd and the measured value of the voltage Vcs over unit time h. More specifically, the parameter calculation unit 5 calculates the value of the equivalent capacitor Cd based on the above equation (8). This allows the value of the equivalent capacitor Cd to be calculated accurately using a simpler equation.

[0163] In addition, the parameter calculation unit 5 acquires sampling data including the measurement values ​​of the voltage Vcd and the voltage Vcs sampled by the measurement unit 4 every unit time h, and calculates the value of the equivalent capacitor Cd for each data pair consisting of sampling data from two adjacent sampling points. This allows the value of the equivalent capacitor Cd to be obtained for each unit time h, making it possible to calculate the change in the value of the equivalent capacitor Cd over time. In addition, by calculating the average or median value of the equivalent capacitor Cd for each unit time h, it is possible to estimate the value (fixed value) of the equivalent capacitor Cd of the winding 11.

[0164] In this way, the test device 1 according to this embodiment makes it possible to accurately calculate parameters relating to the winding under test even when magnetic saturation occurs.

[0165] The analysis period Tb for the equivalent capacitor Cd is the period immediately after the switch SW is turned on. This allows the value of the equivalent capacitor Cd to be obtained before the equivalent inductor Ld and the equivalent resistance Rd are calculated, so that the subsequent analysis process for the equivalent inductor Ld and the equivalent resistance Rd can be performed quickly.

[0166] Furthermore, the parameter calculation unit 5 sets the analysis period Tb for the equivalent capacitor Cd to a period during which the voltage Vcd is rising, excluding a predetermined period Tx1 immediately after the switch SW is turned on and a predetermined period Tx2 immediately before the voltage Vcd reaches its maximum value Vmax, as shown in FIG. 4.

[0167] As described above, this makes it possible to suppress the effects of ringing caused by parasitic capacitance and parasitic inductance, waveform distortion caused by the influence of a control circuit (not shown), and the like, and therefore makes it possible to calculate each parameter related to winding 11 with higher accuracy.

[0168] Furthermore, by setting the analysis period Tb as the period from time tα when the measured value of the voltage Vcd becomes α(0≦α<100)% of the maximum value Vmax of the voltage Vcd to time tβ when the measured value of the voltage Vcd becomes β(α<β≦100)% of the maximum value Vmax of the voltage Vcd, as shown in FIG. 4, the parameter calculation unit 5 can easily determine the analysis period Tb.

[0169] Furthermore, in the test apparatus 1 according to this embodiment, the display unit 7 displays a waveform showing the change over time in the value of at least one of the equivalent capacitor Cd, the equivalent inductor Ld, and the equivalent resistance Rd for the winding 11 under test calculated by the parameter calculation unit 5.

[0170] This makes it easy for the user to determine whether magnetic saturation has occurred and to analyze changes in the equivalent capacitor Cd, equivalent inductor Ld, and equivalent resistance Rd caused by magnetic saturation.

[0171] Furthermore, when displaying waveforms relating to each calculated parameter, the display unit 7 can display not only waveforms showing the temporal changes in the values ​​of the equivalent inductor Ld and the equivalent resistance Rd, but also waveforms showing the temporal changes in the values ​​of the equivalent inductor Ld and the equivalent resistance Rd as waveforms in other formats. For example, as described above, it is possible to display a waveform showing the temporal change in the reciprocal (1 / Ld) of the value of the equivalent inductor Ld, or a waveform showing the temporal change in the value (Rd / Ld) obtained by dividing the value of the equivalent resistance Rd by the value of the equivalent inductor Ld. This allows the user to analyze the characteristics of the winding 11 more easily, since even if there is a period in which the values ​​of the equivalent inductor Ld and the equivalent resistance Rd diverge due to the occurrence of magnetic saturation, the waveforms can be changed and displayed so that the values ​​do not diverge, as shown in FIGS. 14 and 15.

[0172] <<Extension of Embodiment>> The invention made by the inventor of the present application has been specifically described above based on an embodiment, but it goes without saying that the present invention is not limited thereto and can be modified in various ways without departing from the spirit of the invention.

[0173] For example, in the above embodiment, the value of the equivalent capacitor Cd is calculated using the above-mentioned method and stored in the memory unit 8, and the values ​​of the equivalent inductor Ld and the equivalent resistance Rd are calculated using the value of the equivalent capacitor C stored in the memory unit 8, but this is not limited to this. For example, if it is known that the value of the equivalent capacitor Cd of the winding 11 under test is sufficiently smaller than the value of the impulse voltage application capacitor Cs, the value of the equivalent capacitor Cd can be assumed to be Cd = Cs / 100, and the assumed value can be stored in advance in the storage unit 8. For example, a user can input the value of the equivalent capacitor Cd by operating the instruction input unit 3, and the parameter calculation unit 5 can store the value input by the user in the storage unit 8. The parameter calculation unit 5 can then use the value of the equivalent capacitor stored in the storage unit 8 to calculate the values ​​of the equivalent inductor Ld and the equivalent resistance Rd using the method described above. This eliminates the need for the test apparatus 1 to analyze the equivalent capacitor Cd, and the analysis of the winding 11 can be completed in a shorter time.

[0174] Furthermore, in the above embodiment, the unit time h is described as a time corresponding to one sampling period by the measurement unit 4, but this is not limited to this. For example, the unit time h may be a time based on a sampling period, such as two sampling periods or three sampling periods.

[0175] In the above embodiment, the average value Iave of the current Icd during the period from time t=a to time t=a+h is set to the average value of the current Icd at two sampling points (see equation (3)), but this is not limiting. For example, the average value Iave may be set to the average value of the current Icd at three or more sampling points.

[0176] Furthermore, in the above embodiment, the test apparatus 1 is illustrated as including a backflow prevention diode D, but the test apparatus 1 does not have to include a backflow prevention diode D. Furthermore, if the test apparatus 1 is not required to have a waveform display function, the test apparatus 1 does not have to include the waveform generating unit 6 and the display unit 7.

[0177] Furthermore, the above-described flowcharts are merely examples for explaining the operation, and are not intended to be limiting. That is, the steps shown in each diagram of the flowchart are specific examples, and the present invention is not limited to these flows. For example, the order of some processes may be changed, other processes may be inserted between processes, or some processes may be performed in parallel. [Explanation of symbols]

[0178] 1...Test equipment, 2...Impulse voltage generating circuit, 3...Instruction input section, 4...Measurement section, 5...Parameter calculation section, 6...Waveform generation section, 7...Display section, 8...Memory section, 81...Measurement value information, 82...Formula information, 83...Analysis result information, 84...Waveform data, Cs...Capacitor for applying impulse voltage, Cd...Equivalent capacitor of winding 11, Ld...Equivalent inductor of winding 11, Rd...Equivalent resistance of winding 11, Rs...Current limiting resistor, D...Rectifier element (diode for preventing reverse current), E...Impulse voltage, Ta, Tb, Tc...Analysis period, Vmax...Maximum value of voltage Vcd, Vmin...Minimum value of voltage Vcd, T1...External terminal (first external terminal), T2...External terminal (second external terminal), 70...Display.

Claims

1. a first external terminal to which one terminal of a winding under test is connected, and a second external terminal to which the other terminal of the winding is connected; an impulse voltage applying capacitor, one end of which is connected to the second external terminal; a switch connected between the other end of the impulse voltage application capacitor and the first external terminal; a current limiting resistor connected in series with the switch between the other end of the impulse voltage application capacitor and the first external terminal; an instruction input unit that turns on the switch in response to an instruction to start a test; a measuring unit that measures a first voltage between the first external terminal and the second external terminal and a second voltage across the impulse voltage application capacitor; a parameter calculation unit that calculates, when the winding is equivalently represented by an equivalent inductor connected between the first external terminal and the second external terminal, an equivalent capacitor connected between the first external terminal and the second external terminal, and an equivalent resistor connected in series with the equivalent inductor between the first external terminal and the second external terminal, a change over time in a value of at least one of the equivalent inductor and the equivalent resistance based on the measured value of the first voltage and the measured value of the second voltage measured by the measurement unit; a storage unit configured to store measurement value information including a measurement value of the first voltage and a measurement value of the second voltage measured by the measurement unit, and a value of the equivalent capacitor; The parameter calculation unit Using the measured values ​​of the first voltage and the second voltage for each unit time during a predetermined period from when the switch is turned on until resonance based on the equivalent inductor, the equivalent capacitor, and the equivalent resistance of the winding starts, which are stored in the storage unit, and the value of the equivalent capacitor stored in the storage unit, a regression analysis is performed based on an equation for the transient response of the first voltage and an equation for the transient response of the second voltage in an equivalent circuit formed by the equivalent inductor, the equivalent capacitor, and the equivalent resistance of the winding, the impulse voltage application capacitor, and the current limiting resistor during the predetermined period, thereby calculating the value for each unit time of at least one of the equivalent inductor and the equivalent resistance. Test equipment.

2. 2. The test device according to claim 1, When the value of the equivalent inductor is Ld, the value of the equivalent capacitor is Cd, the value of the equivalent resistance is Rd, the value of the impulse voltage application capacitor is Cs, the value of the current limiting resistor is Rs, the first voltage is Vcd, the second voltage is Vcs, and time is t, an equation of the transient response of the first voltage is expressed by the following equation (1), and an equation of the transient response of the second voltage is expressed by the following equation (2). Test equipment. [Equation 1] [Equation 2]

3. 3. The test device according to claim 1, The parameter calculation unit a value of the equivalent capacitor is calculated based on the measured value of the first voltage and the measured value of the second voltage during a first period during which the current flowing through the equivalent inductor can be considered to be zero within a period during which the first voltage is rising immediately after the switch is turned on, and the calculated value is stored in the storage unit; Test equipment.

4. 4. The test device according to claim 3, The parameter calculation unit calculates a value of the equivalent capacitor based on a relational expression between an amount of change in charge of the equivalent capacitor in the unit time and an amount of change in the first voltage in the unit time, the amount of change being represented by the measured value of the first voltage and the measured value of the second voltage in the unit time. Test equipment.

5. 5. The test device according to claim 4, When the measurement value of the second voltage at time a in the first period is Vcs|t=a, the measurement value of the first voltage at the time a is Vcd|t=a, the measurement value of the second voltage at time a+h which is earlier than the time a by the unit time h is Vcs|t=a+h, the measurement value of the first voltage at the time a+h is Vcd|t=a+h, the value of the current limiting resistor is Rs, and the value of the equivalent capacitor is Cd, The parameter calculation unit calculates the value of the equivalent capacitor per unit time based on the following equation (3): Test equipment. [Equation 3]

6. 6. The test device according to claim 3, the measurement unit samples the first voltage and the second voltage for each unit time; The parameter calculation unit acquires sampling data including the measurement value of the first voltage and the measurement value of the second voltage sampled by the measurement unit, and calculates the value of the equivalent capacitor for each data pair, which is a set of the sampling data at two adjacent sampling points. Test equipment.

7. 7. The test device according to claim 3, The first period is a period during which the first voltage is rising, excluding a predetermined period immediately after the switch is turned on and a predetermined period immediately before the first voltage reaches its maximum value. Test equipment.

8. 8. The test device according to claim 7, The first period is a period from a time when the measured value of the first voltage becomes α (0≦α<100)% of the maximum value of the first voltage to a time when the measured value of the first voltage becomes β (α<β≦100)% of the maximum value of the first voltage. Test equipment.

9. 9. The test device according to claim 1, The apparatus further includes a waveform generating unit that generates waveform data indicating a change over time in the value of at least one of the equivalent capacitor, the equivalent inductor, and the equivalent resistance calculated by the parameter calculating unit, and a display unit that displays a waveform based on the waveform data. Test equipment.

10. 10. The test device according to claim 9, The display unit displays a waveform showing a change over time in the reciprocal of the value of the equivalent inductor. Test equipment.

11. 11. The test device according to claim 9 or 10, The display unit displays a waveform showing a change over time in a value obtained by dividing the value of the equivalent resistance by the value of the equivalent inductor. Test equipment.

12. A test method using a test device including: a first external terminal to which one terminal of a winding to be tested is connected; a second external terminal to which the other terminal of the winding is connected; an impulse voltage application capacitor having one end connected to the second external terminal; a switch connected between the other end of the impulse voltage application capacitor and the first external terminal; and a current limiting resistor connected in series with the switch between the other end of the impulse voltage application capacitor and the first external terminal, a first step of turning on the switch; a second step of measuring a first voltage between the first external terminal and the second external terminal and a second voltage across the impulse voltage application capacitor; a third step of calculating, based on the measured value of the first voltage and the measured value of the second voltage measured in the second step, a change over time in at least one of an equivalent inductor connected between the first external terminal and the second external terminal, an equivalent capacitor connected between the first external terminal and the second external terminal, and an equivalent resistor connected in series with the equivalent inductor between the first external terminal and the second external terminal, when the winding is equivalently represented by the equivalent inductor and the equivalent capacitor connected between the first external terminal and the second external terminal, The third step is Using the measured values ​​of the first voltage and the second voltage for each unit time during a predetermined period from when the switch is turned on until resonance based on the equivalent inductor, the equivalent capacitor, and the equivalent resistance of the winding starts, and the value of the equivalent capacitor stored in the test device, a regression analysis is performed based on an equation for the transient response of the first voltage and an equation for the transient response of the second voltage in an equivalent circuit formed by the equivalent inductor, the equivalent capacitor, and the equivalent resistance of the winding, the impulse voltage application capacitor, and the current limiting resistor during the predetermined period, thereby calculating the value for each unit time of at least one of the equivalent inductor and the equivalent resistance. Test method.

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