Test equipment and test method

Abstract

To make it possible to easily analyze characteristics of a winding to be tested in a shorter time.SOLUTION: A test device 1 includes: a capacitor Cs for impulse voltage application whose one end is connected to an external terminal T2; a switch SW and a current limiting resistor Rs connected in series between the other end of the capacitor Cs for impulse voltage application and an external terminal T1; and a parameter calculation unit 5. The parameter calculation unit 5 calculates at least one of a value of an equivalent capacitor Cd, a value of an equivalent inductor Ld, and a value of an equivalent resistor Rd, by performing a regression analysis using a measured value of a voltage Vcd during an analysis 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 resistor Rd related to a winding 11 starts.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Conventionally, an impulse winding test device is known for measuring the characteristics of windings of rotating machines such as electric motors and generators. This device 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 composed of the winding and the internal circuit of the test device, based on the voltage change when an impulse voltage is applied to the winding under test (see Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 4508211 [Overview of the project] [Problems that the invention aims to solve]

[0004] Conventional impulse winding test devices, such as those described in Patent Document 1, can calculate 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. However, they cannot calculate each parameter individually. Therefore, for example, when comparing LC or RC values ​​between multiple windings or measuring the change over time of a single winding, it is not possible to determine which of the inductance, capacitance, and resistance parameters differ or which parameter has changed over time, making it difficult to analyze the characteristics of the winding.

[0005] Furthermore, most conventional impulse winding test devices are equipped with a reverse current prevention diode to prevent current from flowing back from the winding to the internal circuit of the impulse winding test device after an impulse voltage has been applied to the winding under test. Such impulse winding test devices calculate the LC and RC values ​​using the waveform of the resonance phenomenon based on the winding under test that occurs after the internal circuit of the impulse winding test device and the winding under test are electrically isolated by the reverse current prevention diode after the impulse voltage has been applied. Therefore, it is necessary to measure the resonance waveform after the internal circuit of the impulse winding test device and the winding under test are electrically isolated by the reverse current prevention diode, which presents the challenge of long measurement times.

[0006] This invention has been made in view of the above-mentioned problems, and aims to enable the analysis of the characteristics of a winding under test in a shorter time and more easily. [Means for solving the problem]

[0007] A test apparatus according to a representative embodiment of the present invention comprises: 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 applying capacitor having one end connected to the second external terminal; a switch connected between the other end of the impulse voltage applying capacitor and the first external terminal; a current limiting resistor connected in series with the switch between the other end of the impulse voltage applying capacitor and the first external terminal; an instruction input unit that receives a test start instruction; a voltage measuring unit that measures a voltage between the first external terminal and the second external terminal; a storage unit that stores measurement value information including the measured value of the voltage measured by the voltage measuring unit; 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 between the first external terminal and the second external terminal in series with the equivalent inductor, a parameter calculation unit that calculates at least one of the value of the equivalent inductor, the value of the equivalent capacitor, and the value of the equivalent resistor based on the measurement value information stored in the storage unit; wherein the instruction input unit turns on the switch in response to the test start instruction, and the parameter calculation unit performs regression analysis using measured values of the voltage in a predetermined period from when the switch is turned on to when resonance based on the equivalent inductor, the equivalent capacitor, and the equivalent resistor of the winding starts among the measurement value information stored in the storage unit, thereby calculating at least one of the value of the equivalent capacitor, the value of the equivalent inductor, and the value of the equivalent resistor. [Advantages of the Invention]

[0008] According to the test apparatus of the present invention, it is possible to analyze the characteristics of the winding to be tested more easily in a shorter time. [Brief Description of Drawings]

[0009] [Figure 1] It is a diagram showing the configuration of the test apparatus according to Embodiment 1. [Figure 2] It is a diagram showing an equivalent circuit when a winding to be tested is connected to the test apparatus according to the first embodiment. [Figure 3] It is a diagram showing an example of characteristics of a voltage Vcd across both ends of the winding when an impulse voltage is applied between external terminals in a state where the winding is connected to the test apparatus according to the first embodiment. [Figure 4] It is a diagram showing an equivalent circuit of the test apparatus according to the first embodiment during an analysis period Ta. [Figure 5] It is a diagram showing an example of a display screen of the test apparatus according to the first embodiment. [Figure 6] It is a flowchart showing the flow of a winding analysis method using the test apparatus according to the first embodiment. [Figure 7] It is a diagram showing a configuration of a test apparatus according to the second embodiment. [Figure 8] It is a diagram showing an example of an equivalent circuit based on an impulse voltage generation circuit and the winding when a switch is turned on in the test apparatus according to the second embodiment. [Figure 9] It is a diagram showing an example of an equivalent circuit based on an impulse voltage generation circuit and the winding after a switch is turned on (t>0) in the test apparatus according to the second embodiment. [Figure 10] It is a flowchart showing the flow of a winding analysis method using the test apparatus according to the second embodiment. [Figure 11] It is a diagram showing a configuration of a test apparatus according to the third embodiment. [Figure 12] It is a diagram showing an example of an error between a theoretical waveform and a measured waveform of the voltage Vcd when the initial value Vcd|t=0 of the voltage Vcd is changed. [Figure 13] It is a diagram showing an example of an equivalent inductor Ld when the initial value Vcd|t=0 of the voltage Vcd is changed. [Figure 14] It is a diagram showing an example of an equivalent capacitor Cd when the initial value Vcd|t=0 of the voltage Vcd is changed. [Figure 15] It is a diagram showing an example of an equivalent resistor Rd when the initial value Vcd|t=0 of the voltage Vcd is changed. [Figure 16] This flowchart shows the flow of the winding analysis method using the test apparatus according to Embodiment 3. [Modes for carrying out the invention]

[0010] 1. Overview of the Embodiment First, a general overview of a typical embodiment of the invention disclosed in this application will be provided. In the following description, as an example, reference numerals on the drawings corresponding to the components of the invention are indicated in parentheses.

[0011] [1] A test apparatus (1, 1A, 1B) according to a typical embodiment of the present invention comprises: a first external terminal (T1) to which one terminal of the 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) with 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; an instruction input unit (3) for receiving instructions to start the test; a voltage measurement unit (4) for measuring the voltage (Vcd) between the first external terminal and the second external terminal; a storage unit (8) for storing measurement value information (81) including the measured voltage measured by the voltage measurement unit; and the winding, an equivalent inductor (Ld) connected between the first external terminal and the second external terminal, and the first external terminal and the The device includes a parameter calculation unit (5, 5A, 5B) that calculates at least one of the equivalent inductor value, the equivalent capacitor value, and the equivalent resistance value, which are equivalently represented by an equivalent capacitor (Cd) connected to a second external terminal and an equivalent resistance (Rd) connected in series with the inductor between the first external terminal and the second external terminal, based on the measured value information stored in the storage unit. The instruction input unit turns on the switch in response to the instruction to start the test, and the parameter calculation unit calculates at least one of the equivalent capacitor value, the equivalent inductor value, and the equivalent resistance value by performing regression analysis using the measured voltage values ​​from the measured value information stored in the storage unit during a predetermined period (Ta) from when the switch is turned on until resonance based on the equivalent inductor, equivalent capacitor, and equivalent resistance of the winding starts.

[0012] [2] The test apparatus described in [1] above may further include a rectifier element (D) connected in series with the switch and the current limiting resistor between the other end of the impulse voltage application capacitor and the first external terminal, which allows current to pass from the impulse voltage application capacitor side to the first external terminal side and blocks current from the first external terminal side to the impulse voltage application capacitor side.

[0013] [3] In the test apparatus described in [1] or [2] above, the parameter calculation unit may detect the maximum point (Pmax) where the voltage is at its maximum and the minimum point (Pmin) where the voltage is at its minimum after the switch is turned on, and the period between the maximum point and the minimum point may be defined as the predetermined period (Ta).

[0014] [4] In the test apparatus (1) described in any of [1] to [3] above, the parameter calculation unit (5) performs regression analysis using the measured voltage values ​​during the predetermined period to calculate the coefficients of the equation for the transient response of the voltage in the equivalent circuit (20) composed of the equivalent inductor, the equivalent capacitor, the equivalent resistance, the impulse voltage application capacitor, and the current limiting resistor, and calculates the value of the equivalent capacitor, the value of the equivalent inductor, and the equivalent resistance based on the calculated coefficients. value You may calculate this.

[0015] [5] In the test apparatus described in [4] above, the transient response equation may be an equation obtained by integrating multiple times with respect to time the differential equation representing the temporal change of the voltage in the equivalent circuit.

[0016] [6] In the test apparatus described in [5] above, the transient response equation is an equation obtained by integrating the differential equation three times with respect to time, where Ld is the value of the equivalent inductor, Cd is the value of the equivalent capacitor, Rd is the value of the equivalent resistance, Cs is the value of the impulse voltage application capacitor, Rs is the value of the current limiting resistor, Vcd is the voltage between the first external terminal and the second external terminal, and t is the time, the equation obtained by integrating three times may be expressed as equation (2) described later.

[0017] [7] In the test apparatus described in [5] above, the transient response equation is an equation obtained by integrating the differential equation twice with respect to time, where Ld is the value of the equivalent inductor, Cd is the value of the equivalent capacitor, Rd is the value of the equivalent resistance, Cs is the value of the impulse voltage application capacitor, Rs is the value of the current limiting resistor, Vcd is the voltage between the first external terminal and the second external terminal, and t is the time, the equation obtained by integrating twice may be expressed as equation (11) described later.

[0018] [8] The test apparatus (1) described in any of [4] to [7] above may further include a waveform generation unit (6) that generates a theoretical waveform (310) of the voltage by numerically integrating using the transient response equation to which the equivalent capacitor value, the equivalent inductor value, and the equivalent resistance value calculated by the parameter calculation unit are applied, and a display unit (7) that displays the theoretical waveform generated by the waveform generation unit and the measured waveform (300) of the voltage measured by the voltage measurement unit.

[0019] [9] In the test apparatus (1A, 1B) described in [1] or [2] above, the parameter calculation unit (5A, 5B) calculates the initial value of the voltage (Vcd| during the predetermined period. t=0 ) is the charging voltage of the impulse voltage application capacitor ( Vcs ) to the impulse voltage application capacitor ( CsThe parameter calculation unit calculates the value of the equivalent capacitor based on an equation showing the relationship between the impulse voltage application capacitor and the equivalent capacitor, assuming that the voltage divided by the equivalent capacitor (Cd) matches the value of the equivalent capacitor, and based on the measured value information stored in the memory unit. The parameter calculation unit then calculates the coefficients of the equation for the transient response of the voltage in the equivalent circuit (22) composed of the equivalent inductor and the equivalent resistance, the impulse voltage application capacitor and the current limiting resistor, by performing regression analysis using the measured voltage values ​​over a predetermined period. Based on the calculated coefficients and the initial value of the voltage, the parameter calculation unit may calculate the value of the equivalent inductor and the value of the equivalent resistance.

[0020]

[10] The test apparatus (1B) described in [9] above further comprises a waveform generation unit (6) that generates a theoretical waveform of the voltage by numerically integrating using the transient response equation to which the equivalent capacitor value, the equivalent inductor value, and the equivalent resistance value calculated by the parameter calculation unit (5B) are applied, and an error calculation unit (9) that calculates the error between the theoretical waveform generated by the waveform generation unit and the measured waveform of the voltage measured by the voltage measurement unit, wherein the parameter calculation unit may use the equivalent capacitor value, the equivalent inductor value, and the equivalent resistance value that minimize the error as the winding analysis result.

[0021]

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

[10] above, the transient response equation may be an equation obtained by integrating with respect to time the differential equation representing the time change of the voltage of the equivalent circuit.

[0022]

[12] In the test apparatus described in

[11] 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 voltage between the first external terminal and the second external terminal is Vcd, and time is t, the equation for the transient response is an equation obtained by integrating the differential equation from time t=0 to time t=a (a>0), and may be expressed as equation (21) or equation (22) described later.

[0023]

[13] A typical embodiment of the present invention is a test method using a test apparatus (1) comprising a first external terminal (T1) to which one terminal of the 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) with 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 the voltage between the first external terminal and the second external terminal, and a third step (S5~S7, S7A, S8A) of calculating the value of the equivalent inductor, the value of the equivalent capacitor, and the value of the equivalent resistance, 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, based on the measured voltage values ​​measured in the second step. The third step is characterized by including a step (S6, S7, S7A, S8A) of calculating at least one of the equivalent inductor value, the equivalent capacitor value, and the equivalent resistance value by performing a regression analysis using the measured voltage during a predetermined period (Ta) from when the switch is turned on until resonance based on the inductor, capacitor, and resistor of the winding begins.

[0024] 2. Specific Examples of Embodiments Hereinafter, specific examples of embodiments of the present invention will be described with reference to the figures. In the following description, common components in each embodiment will be denoted by the same reference numerals, and repeated descriptions will be omitted.

[0025] <Embodiment 1> Figure 1 shows the configuration of the test apparatus 1 according to Embodiment 1. The test apparatus 1 shown in Figure 1 is a device for measuring the characteristics of windings (coils) that make up rotating machinery such as electric motors and generators, and electrical equipment such as transformers. For example, test apparatus 1 is an impulse winding test apparatus that calculates at least one value of the equivalent inductance, equivalent capacitor, and equivalent resistance, which are parameters related to the winding under test, based on the voltage change when an impulse voltage is applied to the winding under test.

[0026] As shown in Figure 1, the test apparatus 1 includes external terminals T1 and T2, an impulse voltage generation circuit 2, an instruction input unit 3, a voltage measurement unit 4, a parameter calculation unit 5, a waveform generation unit 6, a display unit 7, and a storage unit 8.

[0027] External terminals T1 and T2 are terminals for connecting the winding 11 as the test object (DUT). For example, one terminal of the winding 11 is connected to external terminal T1, and the other terminal of the winding 11 is connected to external terminal T2.

[0028] The impulse voltage generation circuit 2 is a circuit for applying a desired impulse voltage to the winding 11 under test, which is connected between external terminals T1 and T2. The impulse voltage generation circuit 2 includes, for example, an impulse voltage application capacitor Cs, a switch SW, and a current limiting resistor Rs.

[0029] The impulse voltage application capacitor Cs is a capacitor that charges to generate the impulse voltage E. One end of the impulse voltage application capacitor Cs is connected to the external terminal T2.

[0030] A switch SW is an element used to switch the output of an impulse voltage E on or off. A switch SW is implemented using a semiconductor element such as a power transistor or thyristor. The switch SW is connected between the other end of the impulse voltage application capacitor Cs and the external terminal T1.

[0031] The current-limiting resistor Rs is a component that limits the current flowing from the external terminal T1 to the winding 11 under test when the impulse voltage application capacitor Cs is discharged. The current-limiting resistor Rs is connected in series with a switch SW between the other end of the impulse voltage application capacitor Cs and the external terminal T1.

[0032] The rectifier element D is a component that allows current to pass from the impulse voltage application capacitor Cs to the external terminal T1, and blocks current from the external terminal T1 to the impulse voltage application capacitor Cs. The rectifier element D is, for example, a diode. In the following explanation, the rectifier element D will also be referred to as a "reverse current prevention diode D".

[0033] The reverse current blocking diode D is connected in series with a switch SW and a 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 reverse current blocking diode D is connected to one end of the current limiting resistor Rs, and the cathode electrode of the reverse current blocking diode D is connected to the external terminal T1.

[0034] The impulse voltage generation circuit 2 outputs an impulse voltage E via a switch SW between one end of the current limiting resistor Rs and the external terminal T2, in response to an instruction from the instruction input unit 3. For example, first, the impulse voltage application capacitor Cs is charged by a DC power supply (not shown) so that its voltage becomes the impulse voltage E. Next, the switch SW is turned on 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 reverse current prevention diode D, and a voltage Vcd is generated between the external terminals T1 and T2.

[0035] The instruction input unit 3 is a functional unit that receives instructions for the test device 1. The instruction input unit 3 is implemented by, for example, an input interface device such as an operation button or touch panel that accepts user operation of the test device 1, and program processing by a CPU. When the user inputs test conditions such as the value of the impulse voltage E or the sampling frequency (described later), the instruction input unit 3 stores these input values ​​in the storage unit 8, thereby setting the test conditions for the test device 1. In addition, the instruction input unit 3 turns on the switch SW of the impulse voltage generation circuit 2 in response to the user's input of an instruction to start the test.

[0036] The voltage measurement unit 4 is a functional unit that measures the voltage (inter-terminal voltage) Vcd between external terminals T1 and T2. The voltage measurement unit 4 stores measurement information 81, including the measured voltage Vcd, in the storage unit 8.

[0037] Specifically, the voltage measurement unit 4 acquires measured values ​​of voltage Vcd by sampling the voltage Vcd at a predetermined sampling period. The voltage measurement unit 4 is configured to include, for example, a resistive voltage divider circuit that divides the voltage Vcd between external terminals T1 and T2, and an A / D conversion circuit that converts the voltage divided by the resistive voltage divider circuit into a digital signal at a predetermined sampling period. The voltage measurement unit 4 acquires time-series data of measured values ​​(sampling data) of voltage Vcd by sampling the voltage Vcd at a predetermined sampling period, and stores this data as measured value information 81 in the storage unit 8.

[0038] The parameter calculation unit 5 is a functional unit that calculates the values ​​of equivalent capacitor, equivalent inductor, and equivalent resistance as parameters for the winding 11 under test. The waveform generation unit 6 is a functional unit that generates data for various waveforms that show the voltage, current, and other characteristics of the winding 11 under test. The detailed functions of the parameter calculation unit 5 and the waveform generation unit 6 will be described later.

[0039] The memory 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, as well as test results of the winding 11 under test. In addition to the measurement value information 81 mentioned above, the memory unit 8 stores, for example, mathematical formula information 82, analysis result information 83, measurement waveform data 84, and theoretical waveform data 85, which will be described later.

[0040] The parameter calculation unit 5, waveform generation unit 6, and storage unit 8 described above are implemented, for example, by a program processing unit. Specifically, in a program processing unit (e.g., 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 counters (timers), A / D conversion circuits, D / A conversion circuits, clock generation circuits, and input / output interface circuits are connected to each other via buses or dedicated lines, the above-mentioned functional blocks are realized by the processor executing various arithmetic processes according to the program stored in memory and controlling peripheral circuits such as A / D conversion circuits and input / output interface circuits based on the processing results.

[0041] The display unit 7 is a functional unit that displays information for setting test conditions, test results, and so on. The display unit 7 is implemented by a display device such as a liquid crystal display.

[0042] Test apparatus 1 analyzes the characteristics of the winding 11 under test by calculating at least one value of the equivalent inductor, equivalent capacitor, and equivalent resistance, which are parameters related to the winding 11, based on the transient response characteristics of the voltage Vcd between external terminals T1 and T2 when an impulse voltage E is applied to the winding 11 connected between external terminals T1 and T2.

[0043] The following describes the specific calculation methods for each parameter related to the winding 11 being tested using the test apparatus 1.

[0044] Figure 2 shows the equivalent circuit when the winding 11 to be tested is connected to the test apparatus 1 according to Embodiment 1. Figure 3 shows an example of the characteristics of the voltage Vcd across both ends of the winding 11 when an impulse voltage is applied between external terminals T1 and T2 while the winding 11 is connected to the test apparatus 1 according to Embodiment 1.

[0045] In Figure 3, the horizontal axis represents elapsed time [μs] and the vertical axis represents voltage [V]. Figure 3 shows the time change of voltage Vcd after the switch SW is turned on, when the capacitor for applying the impulse voltage is charged so that the impulse voltage E is 1000V.

[0046] As shown in Figure 2, the circuit when viewed from the external terminals T1 and T2 towards the winding 11 can be equivalently represented by an equivalent inductor Ld connected between external terminals T1 and T2, an equivalent capacitor Cd connected between external terminals T1 and T2, and an equivalent resistor Rd connected in series with the equivalent inductor Ld between external terminals T1 and T2.

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

[0048] When the switch SW is turned on at time t=0s, no current flows through the equivalent inductor Ld on the winding 11 immediately after the switch SW is turned on. Therefore, the voltage Vcd between the external terminals T1 and T2 rises to approximately 1000V, which is the charging voltage (impulse voltage E) of the impulse voltage application capacitor Cs. However, the extent to which the voltage Vcd rises varies depending on the characteristics of the winding 11.

[0049] Subsequently, current begins to flow through the equivalent inductor Ld via the equivalent resistor Rd, causing the voltage Vcd to decrease. When the voltage Vcd drops to approximately -1000V, the reverse current blocking diode D electrically isolates the impulse voltage generation circuit 2 from the circuit on the winding 11 side. As a result, around time t=10μs in Figure 3, resonance begins in the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistor Rd on the winding 11 side, causing the voltage Vcd to undergo damped oscillation. After that, the voltage Vcd eventually becomes 0V. However, the degree and timing of the voltage Vcd decrease vary considerably depending on the characteristics of the winding 11.

[0050] As described above, conventional impulse winding test equipment calculated the LC and RC values, which are the multiplicative values ​​of the parameters related to the winding under test, based on the measured voltage Vcd during the resonance period Tx due to the equivalent inductance, equivalent capacitor, and equivalent resistance on the winding side.

[0051] In contrast, the test apparatus 1 according to Embodiment 1, as shown in Figure 3, uses a predetermined period Ta as the analysis period, which is 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. Based on the measured voltage Vcd during the analysis period Ta and the transient response equation of the voltage Vcd based on the equivalent circuit during the analysis period Ta, it calculates the respective values ​​of the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd.

[0052] Figure 4 shows the equivalent circuit of the test apparatus 1 according to Embodiment 1 during the analysis period Ta.

[0053] Figure 4 shows the equivalent circuit 20, consisting of the impulse voltage generation circuit 2 and winding 11, during the analysis period Ta, i.e., the period when the switch SW is ON and forward current flows through the reverse current blocking diode D. Note that the switch SW and the reverse current blocking diode D are not shown in Figure 4.

[0054] Ignoring the on-resistance of switch SW, the on-resistance of reverse current blocking diode D, and the forward voltage drop, the impulse voltage generation circuit 2 during the period when switch SW is on and forward current flows through reverse current blocking diode D can be equivalently represented by a current limiting resistor Rs and an impulse voltage application capacitor Cs connected in series between external terminals T1 and T2, as shown in Figure 4.

[0055] In the equivalent circuit 20 shown in Figure 4, the equation representing the temporal change (transient response) of the voltage Vcd between external terminals T1 and T2 after the switch SW is turned on is given by the following equation (1).

[0056]

number

[0057] Assuming that the transient response of voltage Vcd during the analysis period Ta shown in Figure 3 is represented by equation (1) above, regression analysis (e.g., least squares method) is performed based on the measured values ​​of voltage Vcd during the analysis period Ta, and the coefficients of each term in equation (1) above can be calculated to derive the respective values ​​of the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd for the winding 11 under inspection.

[0058] On the other hand, if the observed waveform (measured value) of voltage Vcd contains noise components, the above equation (1) includes a third derivative term, so even if general smoothing is applied to the measured value of voltage Vcd, it may not be possible to sufficiently remove the noise components.

[0059] Therefore, the test apparatus 1 according to Embodiment 1 may use an equation obtained by integrating equation (1) above multiple times with respect to time t as the equation for the transient response of voltage Vcd to calculate the respective values ​​of the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd.

[0060] Here, as an example, we will explain the case where we use the equation obtained by integrating equation (1) three times with respect to time t.

[0061] By integrating equation (1) three times with respect to time t and determining the integration constant using the initial conditions, equation (2) is obtained. Furthermore, as shown in equations (3) through (7) below, the coefficients of each term in equation (2) are replaced with V, W, X, Y, and Z, respectively.

[0062]

number

[0063]

number

[0064]

number

[0065]

number

[0066]

number

[0067]

number

[0068] Since equation (2) does not have a differential term, smoothing is not required for the measured voltage Vcd. Furthermore, because equation (2) has an integral term, the influence of noise can be suppressed. Moreover, since equation (2) has more coefficients than equation (1), it is easier to identify the parameters (Ld, Cd, Rd).

[0069] The method for calculating the parameters (circuit constants) using the above formula (2) is as follows. First, the parameter calculation unit 5 of the test apparatus 1 determines the analysis range Ta. For example, as shown in Figure 3, the parameter calculation unit 5 detects the maximum point Pmax, where the voltage Vcd is at its maximum, and the minimum point Pmin, where the voltage Vcd is at its minimum, after the switch SW is turned on. The parameter calculation unit 5 defines the period between the maximum point Pmax and the minimum point Pmin as the analysis period Ta, and sets the time when the switch SW was turned on as t=0.

[0070] Here, the maximum point Pmax and the minimum point Pmin may be the maximum and minimum points of the measurement waveform based on the time-series data of the voltage Vcd measured by the voltage measurement unit 4, or they may be the maximum and minimum points of the smoothed waveform after smoothing processing has been performed on the time-series data of the voltage Vcd measured by the voltage measurement unit 4.

[0071] Next, the parameter calculation unit 5 uses the measured voltage Vcd data during the analysis period Ta to perform the following: Each of TIFF0007914929000008.tif10169 is calculated. In addition, the parameter calculation unit 5 calculates t and t based on the sampling period of the voltage measurement unit 4. 2 The parameter calculation unit 5 uses these calculated values ​​to create a normal equation using a known regression analysis method (e.g., least squares method), and then calculates the coefficients V to Z of each term in equation (2) by performing calculations such as inverse matrix analysis and LU decomposition.

[0072] Next, the parameter calculation unit 5 calculates the values ​​of the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd based on the calculated coefficients V to Z and the above equations (3) to (7).

[0073] First, the method for calculating the equivalent inductor Ld is as follows: For example, from equation (6) above, the value of the equivalent inductor Ld is expressed by the following equation (8).

[0074]

number

[0075] Here, the impulse voltage E is a known value because it is set before performing the test using the test apparatus 1. Similarly, the impulse voltage application capacitor Cs is also a known value because it is set during the design of the test apparatus 1. Therefore, the parameter calculation unit 5 calculates the value of the equivalent inductor Ld by substituting the values ​​of Cs, E, and Y into equation (8) above.

[0076] Next, the method for calculating the equivalent resistance Rd is as follows: For example, from equation (7) above, the value of the equivalent resistance Rd is expressed by the following equation (9).

[0077]

number

[0078] The parameter calculation unit 5 calculates the value of the equivalent resistance Rd by substituting the previously determined values ​​of Ld and Z into the above equation (9).

[0079] Finally, the method for calculating the equivalent capacitor value Cd is as follows: The value of the equivalent capacitor Cd may be calculated using any one or a combination of equations (3), (4), and (5) relating to the coefficients V, X, and Z. On the other hand, equations (3) to (5) include the value of the current limiting resistor Rs. Although the value of the current limiting resistor Rs itself is known, as mentioned above, in reality, the impulse voltage generation circuit 2 has a switch SW and a reverse current prevention diode D connected in series with the current limiting resistor Rs, and therefore, not only the current limiting resistor Rs but also their on-resistance and forward voltage drop exist between the equivalent capacitor Cd and the external terminal T1.

[0080] Therefore, the voltage Vcd measured by test apparatus 1 is affected by the on-resistance of the current limiting resistor Rs, the switch SW, and the reverse current prevention diode D. Consequently, if the value of the equivalent capacitor Cd is calculated by directly substituting the known value of the current limiting resistor Rs into equations (3), (4), and (5), the estimated value of the equivalent capacitor Cd will include an error component based on the on-resistance and other factors mentioned above.

[0081] Therefore, in order to minimize the influence of errors based on the on-resistance, etc., the test apparatus 1 according to Embodiment 1 may use equation (4) for the coefficient W that minimizes the influence of the estimation error of the current limiting resistor Rs within the measurement specification range. For example, from equation (4) above, the value of the equivalent capacitor Cd is expressed by the following equation (10).

[0082]

number

[0083] The parameter calculation unit 5 may calculate the value of the equivalent capacitor Cd by substituting the previously determined Ld, Rd, and W values ​​and the known Cs, E, and Rs values ​​into the above equation (10).

[0084] The parameter calculation unit 5 stores the calculated equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd values ​​for the winding 11 under inspection in the storage unit 8 as analysis result information 83.

[0085] Here, the information necessary for the above calculation by the parameter calculation unit 5 can be stored in the storage unit 8 in advance. For example, the program for calculating the coefficients V, W, X, Y, and Z from the measured voltage Vcd, the information for equations (3) to (7) above, the value of the current limiting resistor Rs, and the value of the capacitor Cs for applying the impulse voltage can be stored in the storage unit 8 in advance as mathematical 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 a result, the parameter calculation unit 5 can use the mathematical formula information 82 stored in the memory unit 8 and the value of the impulse voltage E set at the start of the test to calculate the respective values ​​of the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd through the calculation described above.

[0086] In the above explanation, the parameter calculation unit 5 provided an example of how it calculates the values ​​of the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd based on equation (2), which is obtained by integrating equation (1) three times. However, it is not limited to this, and the values ​​of the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd may also be calculated based on an equation obtained by integrating equation (1) twice. The following describes how to calculate the values ​​of the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd using the equation obtained by integrating twice.

[0087] By integrating equation (1) above twice with respect to time t and determining the integration constant using the initial conditions, equation (11) is obtained. Furthermore, as shown in equations (12) to (16) below, the coefficients of each term in equation (11) are replaced with V, W, X, Y, and Z, respectively.

[0088]

number

[0089]

number

[0090]

number

[0091]

number

[0092]

number

[0093]

number

[0094] Equation (11) above has one differential term and multiple integral terms, which helps to suppress the effects of noise. Comparing the coefficients of each term in equation (2) when the integral is performed three times with the coefficients of each term in equation (11) when the integral is performed twice, only "Z" is different.

[0095] The method for calculating the parameters (circuit constants) using the above formula (11) is as follows. First, the parameter calculation unit 5 of the test apparatus 1 determines the analysis range Ta. The method for determining the analysis range Ta is the same as when using equation (2) described above.

[0096] Next, the parameter calculation unit 5 uses the measured voltage Vcd data during the analysis period Ta to perform the following: The parameter calculation unit 5 calculates TIFF0007914929000018.tif12169. The parameter calculation unit 5 also calculates t based on the sampling period of the voltage measurement unit 4. Using these calculated values, the parameter calculation unit 5 creates a normal equation using a known regression analysis method and calculates the coefficients V to Z of each term in equation (11) by performing calculations such as inverse matrix analysis and LU decomposition.

[0097] Next, the parameter calculation unit 5 calculates the values ​​of the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd based on the calculated coefficients V to Z and the above equations (12) to (16).

[0098] First, the method for calculating the equivalent inductor Ld is as follows: For example, from equation (15) above, the value of the equivalent inductor Ld is expressed by the following equation (17).

[0099]

number

[0100] As mentioned above, the values ​​of the impulse voltage E and the impulse voltage application capacitor Cs are known. Therefore, the parameter calculation unit 5 calculates the value of the equivalent inductor Ld by substituting the values ​​of Cs, E, and Y into equation (17) above.

[0101] Next, the method for calculating the equivalent resistance Rd is as follows: For example, from equation (16) above, the value of the equivalent resistance Rd is expressed by the following equation (18).

[0102]

number

[0103] The parameter calculation unit 5 calculates the equivalent resistance Rd by substituting the previously determined Ld and Z values ​​into the above equation (18).

[0104] With respect to the equivalent capacitor Cd, the parameter calculation unit 5 can calculate it using any of the above equations (12) to (14), similar to the case where equation (2), obtained by integrating three times as described above, is used.

[0105] As explained above, the parameter calculation unit 15 can determine the values ​​of the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd not only based on equation (2), which is obtained by integrating equation (1) three times with respect to time t, but also based on equation (11), which is obtained by integrating equation (1) twice with respect to time t.

[0106] The test apparatus 1 according to this embodiment has a function to individually calculate the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd values ​​for the winding 11 to be inspected, as described above, and also a function to display the theoretical waveform of the voltage Vcd based on the calculated equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd values. This function will be described in detail below.

[0107] In the test apparatus 1 shown in Figure 1, the waveform generation unit 6 generates a measurement waveform showing the temporal change of voltage Vcd based on the time-series data (measurement information 81) of the voltage measurement unit 4, and stores it in the storage unit 8 as measurement waveform data 84.

[0108] Furthermore, the waveform generation unit 6 generates a theoretical waveform showing the temporal change of voltage Vcd in the equivalent circuit 20 by numerically integrating using the transient response equation (equation (1)) based on the respective values ​​of the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd calculated by the parameter calculation unit 5 (analysis result information 83), and stores it in the storage unit 8 as theoretical waveform data 85.

[0109] The display unit 7 displays a waveform related to the voltage Vcd on the screen based on the measured waveform data 84 and theoretical waveform data 85 generated by the waveform generation unit 6.

[0110] Figure 5 shows an example of the display screen of the test apparatus 1 according to Embodiment 1. As shown in Figure 5, the test apparatus 1 is equipped with a display 70 as one means of realizing the function of a display unit 7. The test apparatus 1 displays information for setting test conditions and test result information on the screen of the display 70. For example, the display 70 is equipped with a touch panel, and some 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.

[0111] Furthermore, the test device 1 may have various physical buttons as means for realizing some of the functions of the instruction input unit 3. For example, as shown in Figure 5, the test device 1 may have a start button (power button) 30 for starting the test device 1, a start button 31 for starting the test, a stop button 32 for stopping the test, etc.

[0112] The display unit 7 displays the measured waveform 300 and theoretical waveform 310 of the voltage Vcd on the screen of the display 70 based on the measured waveform data 84 and theoretical waveform data 85 stored in the storage unit 8. For example, as shown in Figure 5, the display unit 7 displays the measured waveform 300 and theoretical waveform 310 of the voltage Vcd together on the screen of the display 70. For example, the display unit 7 may display the measured waveform 300 and theoretical waveform 310 superimposed as shown in Figure 5, or it may display them side by side in the vertical or horizontal direction on the screen of the display 70.

[0113] Furthermore, the display unit 7 may promptly display the measured waveform 300 and the theoretical waveform 310 on the display 70 after calculating the parameters (Ld, Cd, Rd), or it may display the measured waveform 300 and the theoretical waveform 310 on the display 70 in response to the user's operation of the instruction input unit 3. Alternatively, the display unit 7 may display only one of the measured waveform 300 or the theoretical waveform 310 on the display 70.

[0114] Next, we will explain the procedure for analyzing the winding 11 to be tested using the test apparatus 1 according to Embodiment 1.

[0115] Figure 6 is a flowchart showing the flow of the analysis method for the winding 11 using the test apparatus 1 according to Embodiment 1.

[0116] For example, after the user activates the test device 1 by operating the start button 30, the user sets the test conditions etc. on the test device 1 by touching the display 70 which serves as the instruction input unit 3 (step S1). For example, the user sets the value of the impulse voltage E and the sampling period (sampling frequency) for measuring the voltage Vcd on the test device 1.

[0117] Note that in the initial state after the test device 1 is started, the switch SW of the impulse voltage generation circuit 2 is in the OFF state.

[0118] Next, the user connects the winding 11 to be tested between the external terminals T1 and T2 of the test device 1 (step S 2). Note that the connection of the winding 11 to the test apparatus 1 may be performed before step S1.

[0119] Next, the test device 1 determines whether or not a test execution instruction has been entered 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.

[0120] If the start button 31 is operated (step S3: YES), the test device 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 the 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 Vcd is applied between the external terminals T1 and T2.

[0121] Furthermore, the test apparatus 1 starts measuring the voltage Vcd between external terminals T1 and T2 simultaneously with, for example, step S4 (step S5). Specifically, as described above, the voltage measurement unit 4 measures the voltage Vcd between external terminals T1 and T2 based on the sampling period set in step S1, and stores the time-series data of the measured voltage Vcd as measured value information 81 in the storage unit 8.

[0122] Next, the parameter calculation unit 5 determines the analysis range Ta (step S6). Specifically, the parameter calculation unit 5 detects the maximum point Pmax and minimum point Pmin of the voltage Vcd based on the time-series data of the measured voltage Vcd obtained in step S5 using the method described above, and defines the period between the maximum point Pmax and the minimum point Pmin as the analysis period Ta.

[0123] Next, the parameter calculation unit 5 uses the measured voltage Vcd within the analysis period Ta set in step S6 and the mathematical formula information 82 stored in the storage unit 8 to calculate the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd for the winding 11 using the method described above (step S7).

[0124] Next, the waveform generation unit 6 generates measured waveform data 84 based on the measured voltage Vcd obtained in step S5 using the method described above, and also generates theoretical waveform data 85 using the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd values ​​for the winding 11 calculated in step S7 (step S8).

[0125] Next, the display unit 7 performs step S 8 Based on the measured waveform data 84 and theoretical waveform data 85 generated in the test apparatus 1, the measured waveform 300 and theoretical waveform 310 are displayed superimposed on the screen of the display 70 of the test apparatus 1 (step S9).

[0126] Furthermore, the waveform data generation process (step S8) and the waveform display process (step S9) described above may be executed only when, for example, the user operates the test device 1 and the instruction input unit 3 receives an instruction from the user to display the waveform.

[0127] As described above, the test apparatus 1 according to Embodiment 1 has a parameter calculation unit 5 that calculates the value of the equivalent inductor Ld, the value of the equivalent capacitor Cd, and the value of the equivalent resistance Rd when the winding 11 to be inspected, connected between external terminals T1 and T2, is equivalently represented by an equivalent inductor Ld connected between external terminals T1 and T2, an equivalent capacitor Cd connected between external terminals T1 and T2, and an equivalent resistance Rd connected in series with the equivalent inductor Ld between external terminals T1 and T2, based on the measured value of the voltage Vcd between external terminals T1 and T2 measured by the voltage measurement unit 4.

[0128] The parameter calculation unit 5 calculates at least one value of the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd by performing regression analysis using the measured voltage Vcd values ​​from the measured value information 81 stored in the storage unit 8 during a predetermined period (analysis period Ta) from when the switch SW is turned on until resonance based on the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd on the winding 11 side begins.

[0129] According to this, instead of using the measured voltage Vcd (measured waveform) after resonance has started based on the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd on the winding 11 side, as in conventional impulse winding testers, the measured voltage Vcd before the above resonance starts is used, so the analysis process of the winding 11 can be started more quickly.

[0130] Furthermore, as described above, conventional impulse winding testers use the equation and measured values ​​of the voltage Vcd at resonance, which is determined by the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd on the winding 11 side. Therefore, they can only calculate the multiplicative value of each parameter, such as the LC value and RC value. In contrast, the test apparatus 1 according to Embodiment 1 performs calculations based on the equation of the transient response of the voltage Vcd in the equivalent circuit before resonance begins, so it can calculate the values ​​of the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd individually.

[0131] Thus, according to the test apparatus 1 of Embodiment 1, it is possible to analyze the characteristics of the winding under test in a shorter time and more easily.

[0132] Furthermore, in the test apparatus 1 according to Embodiment 1, the parameter calculation unit 5 detects the maximum point Pmax, where the voltage Vcd is at its maximum, and the minimum point Pmin, where the voltage Vcd is at its minimum, after the switch SW is turned on, and defines the period between the maximum point Pmax and the minimum point Pmin as the analysis period Ta. According to this, the analysis period Ta to which the transient response equation based on the equivalent circuit 20 can be applied can be easily determined.

[0133] Furthermore, the test apparatus 1 may also have a reverse current prevention diode D as a rectifier element, which is connected in series with a switch SW and a current limiting resistor Rs between the other end of the impulse voltage application capacitor Cs and the external terminal T1, allowing current to flow from the impulse voltage application capacitor Cs side to the external terminal T1 side and blocking current from the external terminal T1 side to the impulse voltage application capacitor Cs side. According to this, it becomes possible to clearly separate the analysis period Ta by the test apparatus 1 from the resonance period Tx due to the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd on the winding 11 side. Therefore, by observing the measured waveform of the voltage Vcd, the user can easily determine at what timing the resonance due to the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd began.

[0134] Furthermore, the parameter calculation unit 5 performs regression analysis using the measured values ​​of voltage Vcd over a predetermined period (analysis period Ta) to calculate the coefficients of the equation for the transient response of voltage Vcd in the equivalent circuit (see Figure 4) composed of an equivalent inductor Ld, an equivalent capacitor Cd, an equivalent resistance Rd, an impulse voltage application capacitor Cs, and a current limiting resistor Rs. Based on the calculated coefficients, it determines the value of the equivalent capacitor Cd, the value of the equivalent inductor Ld, and the equivalent resistance Rd value Calculate. This allows for more accurate calculation of the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd.

[0135] Furthermore, the transient response equation of the equivalent circuit 20 used in the analysis of the winding 11 described above by the test apparatus 1 may be an equation obtained by integrating multiple times the differential equation (equation (1)) that represents the temporal change of the voltage Vcd in the equivalent circuit 20.

[0136] As described above, equation (1), which represents the transient response of the voltage Vcd in the equivalent circuit 20, includes a third derivative term. Therefore, if equation (1) is used as is, there is a possibility that noise components included in the waveform of the measured voltage Vcd will be amplified. In contrast, the test apparatus 1 according to Embodiment 1 uses an equation obtained by integrating equation (1) multiple times, thereby reducing the derivative term and suppressing the influence of noise components included in the waveform of the measured voltage Vcd.

[0137] For example, by using equation (11), which is obtained by integrating equation (1) twice, the differential term can be reduced, so the voltage V cd Noise components included in the measured value can be effectively suppressed. Furthermore, by using equation (2), which is obtained by integrating equation (1) three times, the derivative term can be further reduced, so the voltage V cd This allows for more effective suppression of noise components included in the measured values.

[0138] It is also possible to use the formula obtained by integrating the above formula (1) once.

[0139] Furthermore, the test apparatus 1 according to Embodiment 1 includes a waveform generation unit 6 that generates a theoretical waveform of voltage Vcd by numerically integrating using the transient response equation based on the value of the equivalent capacitor Cd, the equivalent inductor Ld, and the equivalent resistance Rd on the winding 11 side calculated by the parameter calculation unit 5, and a display unit 7 that displays the theoretical waveform 310 generated by the waveform generation unit 6 and the measured waveform 300 of voltage Vcd measured by the voltage measurement unit 4.

[0140] According to this, the user can visually compare the measured waveform 300 that was actually measured with the theoretical waveform 310 obtained by analysis, making it easy to determine whether the parameters related to the winding 11 (equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd) obtained by the analysis of the test apparatus 1 are appropriate values.

[0141] <Embodiment 2> Figure 7 shows the configuration of the test apparatus 1A according to Embodiment 2.

[0142] Generally, if the winding under test has a core, the iron loss in the core will cause significant attenuation of the waveform. Furthermore, applying a high voltage to the winding will cause magnetic saturation in the core, leading to large changes in parameters such as the winding's inductance and increased nonlinearity.

[0143] Conventional impulse winding test devices, as described above, calculate LC and RC values ​​using the waveform of the resonance phenomenon after the internal circuit of the impulse winding test device and the winding under test are electrically separated by a reverse current prevention diode. Therefore, if the waveform is attenuated, the error in parameter calculation becomes large. Also, if magnetic saturation occurs, the nonlinearity of the parameters becomes stronger, and the obtained parameters may not be appropriate values.

[0144] Furthermore, if the coil under test has a complex configuration, ringing or large localized fluctuations may occur in the response waveform, resulting in inappropriate values ​​for the winding parameters. In such cases, the winding parameters may become negative or deviate significantly from the actual parameter values.

[0145] Therefore, the test apparatus 1A according to Embodiment 2 reduces the number of unknowns in regression analysis by using a simpler equivalent circuit during an analysis period with low attenuation, thereby avoiding errors arising from the small amplitude of the waveform, and making it difficult to calculate inappropriate values ​​as parameters related to the winding.

[0146] The test apparatus 1A shown in Figure 7 differs from the test apparatus 1 of Embodiment 1 in that it calculates the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd of the winding 11 under test using a simpler method, but is otherwise the same as the test apparatus 1 of Embodiment 1.

[0147] As shown in Figure 7, the test apparatus 1A has a parameter calculation unit 5A instead of the parameter calculation unit 5 according to Embodiment 1.

[0148] The parameter calculation unit 5A calculates the initial value of the voltage Vcd during a predetermined period (analysis period Ta) Vcd| t=0 Assuming that the charging voltage Vcs (=E) of the impulse voltage application capacitor Cs is equal to the voltage obtained by dividing the voltage between the impulse voltage application capacitor Cs and the equivalent capacitor Cd, the value of the equivalent capacitor Cd is calculated based on the equation showing the relationship between the impulse voltage application capacitor Cs and the equivalent capacitor Cd, and the measured value information 81 stored in the memory unit 8.

[0149] Figure 8 shows an example of an equivalent circuit based on the impulse voltage generation circuit 2 and winding 11 when the switch SW is turned on in the test apparatus 1A according to Embodiment 2.

[0150] In the equivalent circuit 21 shown in Figure 8, the current limiting resistor Rs is set to zero (Rs=0), and the on-resistance of the switch SW and the on-resistance of the reverse current prevention diode D are ignored.

[0151] In Embodiment 2, it is assumed that when the switch SW is turned on, i.e., at time t=0, the impulse voltage generation circuit 2 and the winding 11 are represented by an equivalent circuit 21 in which the impulse voltage application capacitor Cs and the equivalent capacitor Cd are connected in parallel with external terminals T1 and T2 in between, as shown in Figure 8.

[0152] Also, the value of the voltage Vcd at time t=0 is the initial value of the voltage Vcd| t=0 Assume that the voltage Vcd is at its maximum value Vmax at time t=0. Then, the initial value of the voltage Vcd| t=0 Assume that (=Vmax) is equal to the voltage obtained by dividing the charging voltage Vcs of the impulse voltage application capacitor Cs by the impulse voltage application capacitor Cs and the equivalent capacitor Cd.

[0153] Based on the above assumption, in the equivalent circuit 21, the following formula ( 19 ) holds. Here, let the initial value of the voltage Vcs of the impulse voltage applying capacitor Cs be Vcs| t=0 , which is assumed to be the charging voltage E (Vcs| t=0 =E).

[0154]

Math

[0155] The parameter calculation unit 5A calculates the value of the equivalent capacitor Cd by substituting the value of the initial value Vcd| t=0 of the voltage Vcd based on the measured value information 81, the value of the impulse voltage applying capacitor Cs, and the initial value Vcs| t=0 (=E) of the voltage Vcs into the above formula (19).

[0156] Note that the value (Vmax) of the initial value Vcd| t=0 of the voltage Vcd based on the measured value information 81 may be, for example, the voltage (actually measured value) at the maximum point Pmax of the time-series data of the voltage Vcd during the period from when the switch SW is turned on until resonance based on the equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistor Rd of the winding 11 starts, or may be the voltage at the maximum point of the smoothed waveform obtained after performing smoothing processing (for example, smoothing processing using a moving average window) on the time-series data of the voltage Vcd.

[0157] Next, the parameter calculation unit 5A assumes that after the switch SW is turned on (t>0), the impulse voltage generating circuit 2 and the winding 11 are represented by an equivalent circuit 22 configured by the equivalent inductor Ld, the equivalent resistor Rd, the impulse voltage applying capacitor Cs, and the current limiting resistor Rs.

[0158] FIG. 9 is a diagram showing an example of the equivalent circuit 22 based on the impulse voltage generating circuit 2 and the winding 11 after the switch SW is turned on (t>0) in the test apparatus 1A according to the second embodiment.

[0159] Note that the switch SW and reverse current blocking diode D are not shown in Figure 9.

[0160] Ignoring the on-resistance of the switch SW, the on-resistance of the reverse current blocking diode D, and the forward voltage drop, the impulse voltage generation circuit 2 during the period when forward current flows through the reverse current blocking diode D after the switch SW is turned on (t>0) can be equivalently represented by a current limiting resistor Rs and an impulse voltage application capacitor Cs connected in series between external terminals T1 and T2, as shown in Figure 9. Furthermore, the circuit on the winding 11 side after the switch SW is turned on (t>0) can be equivalently represented by an equivalent resistance Rd and an equivalent inductor Ld connected in series between external terminals T1 and T2.

[0161] Therefore, in Embodiment 2, the equivalent circuit 22 after the switch SW is turned on (t>0) is the equivalent circuit 20 in Embodiment 1 (see Figure 4) with the equivalent capacitor Cd removed.

[0162] In the equivalent circuit 22, the equation representing the temporal change (transient response) of the voltage Vcd between external terminals T1 and T2 after the switch SW is turned on is given by equation (20) below.

[0163]

number

[0164] The parameter calculation unit 5A performs regression analysis using the measured voltage Vcd over a predetermined period (analysis period Ta) to calculate the coefficients of the transient response equation of voltage Vcd over the predetermined period (equation (20) above), and the calculated coefficients are used to calculate the initial value of voltage Vcd| t=0 Based on this, the equivalent inductor Ld and equivalent resistance Rd are calculated.

[0165] For example, the parameter calculation unit 5A uses a known regression analysis method (e.g., least squares method) to create a normal equation using the time-series data of voltage Vcd during the analysis period Ta stored in the storage unit 8 as measurement information 81, and then calculates the coefficients of each term in equation (20) by performing calculations such as inverse matrix analysis or LU decomposition. Next, the parameter calculation unit 5A calculates the values ​​of the equivalent inductor Ld and the equivalent resistance Rd based on the calculated coefficients and the values ​​of Cs and Rs that are previously stored in the storage unit 8.

[0166] Furthermore, since equation (20) above includes the second derivative, noise included in the measurement result of voltage Vcd is easily amplified. In other words, the second derivative is strongly affected by local waveform changes such as ringing due to parasitic capacitance and parasitic inductance that do not appear in the equivalent circuit 22, so the estimated value of the constant by the least squares method may easily fluctuate.

[0167] Therefore, in order to further improve the calculation accuracy of the equivalent inductor Ld and equivalent resistance Rd, the parameter calculation unit 5A may perform regression analysis based on the equation obtained by integrating the above equation (20) to calculate the equivalent inductor Ld and equivalent resistance Rd.

[0168] For example, parameter calculation Part 5 A may also determine the values ​​of the equivalent inductor Ld and the equivalent resistance Rd based on the following equation (21), which is obtained by performing a definite integral of the above equation (20) once with respect to time t from time t=0 to time t=a.

[0169]

number

[0170] By rearranging equation (21) above, it can be expressed by the following equation (22).

[0171]

number

[0172] The parameter calculation unit 5A uses a known regression analysis method (e.g., least squares method) to create a normal equation (e.g., a system of linear equations) using the time-series data of voltage Vcd during the analysis period Ta stored in the storage unit 8 as measurement information 81, and calculates the coefficients of equation (22) by performing calculations such as inverse matrix or LU decomposition. Next, the parameter calculation unit 5 A Based on the calculated coefficients and the values ​​of Cs and Rs stored in the memory unit 8 beforehand, the equivalent inductor Ld and equivalent resistance Rd are calculated.

[0173] The parameter calculation unit 5A stores the respective values ​​of the equivalent capacitor Cd, equivalent inductor Ld, and equivalent resistance Rd, calculated by the method described above, in the storage unit 8 as analysis result information 83A.

[0174] Similar to Embodiment 1, the information necessary for the above calculation by the parameter calculation unit 5A can be stored in the storage unit 8 in advance. For example, the calculation formula for calculating the coefficients of equation (20), equation (21), or equation (22) from the measured voltage Vcd, the value of the current limiting resistor Rs, and the value of the impulse voltage application capacitor Cs can be stored in the storage unit 8 in advance as mathematical formula information 82A. As a result, the parameter calculation unit 5A can use the measured value information 81, formula information 82, and the value of the impulse voltage E set at the start of the test, all stored in the memory unit 8, to calculate the respective values ​​of the equivalent capacitor Cd, equivalent inductor Ld, and equivalent resistor Rd through the calculations described above.

[0175] In the test apparatus 1A according to Embodiment 2, the waveform generation unit 6 generates a measurement waveform 300 showing the temporal change of voltage Vcd based on time-series data (measurement information 81) of the measured voltage Vcd measured by the voltage measurement unit 4, similar to the test apparatus 1 according to Embodiment 1, and stores it in the storage unit 8 as measurement waveform data 84. Furthermore, the waveform generation unit 6 generates a theoretical waveform 310 showing the temporal change of voltage Vcd in the equivalent circuit 22 by numerically integrating using the transient response equation (equation (20) above) based on the respective values ​​of the equivalent capacitor Cd, equivalent inductor Ld, and equivalent resistance Rd calculated by the parameter calculation unit 5A (analysis result information 83A), and stores it in the storage unit 8 as theoretical waveform data 85.

[0176] Similar to the test apparatus 1 according to Embodiment 1, the display unit 7 displays the measured waveform 300 and theoretical waveform 310 of voltage Vcd on the display 70 screen based on the measured waveform data 84 and theoretical waveform data 85 stored in the storage unit 8.

[0177] Next, we will explain the procedure for analyzing the winding 11 to be tested using the test apparatus 1A according to Embodiment 2.

[0178] Figure 10 is a flowchart showing the flow of the analysis method for the winding 11 using the test apparatus 1A according to Embodiment 2.

[0179] In the flowchart shown in Figure 10, the processes from step S1 to step S6 are the same as in the flowchart according to Embodiment 1 (Figure 6).

[0180] After step S6, the parameter calculation unit 5A calculates the initial value of the voltage Vcd at time t=0 in the analysis period Ta set in step S6 using the method described above. t=0 Using (=Vmax) and the mathematical formula information 82A stored in the memory unit 8, the equivalent capacitor Cd for the winding 11 is calculated (step S7A).

[0181] Next, the parameter calculation unit 5A calculates the equivalent inductor Ld and equivalent resistance Rd for the winding 11 using the method described above, with respect to the time-series data of the measured voltage Vcd from time t=0 onwards in the analysis period Ta set in step S6 and the mathematical formula information 82A stored in the storage unit 8 (step S8A).

[0182] Next, the waveform generation unit 6 generates measured waveform data 84 based on the measured voltage Vcd obtained in step S5 using the method described above, and also generates theoretical waveform data 85 using the equivalent capacitor Cd, equivalent inductor Ld, and equivalent resistance Rd values ​​for the winding 11 calculated in steps S7A and S8A (step S9A).

[0183] Next, the display unit 7 displays, for example, the measured waveform 300 and the theoretical waveform 310 superimposed on the screen of the display 70 of the test apparatus 1, based on the measured waveform data 84 and theoretical waveform data 85 generated in step S9A (step S10A).

[0184] In addition, similar to the test apparatus 1 according to Embodiment 1, the waveform data generation process (step S9A) and the waveform display process (step S10A) described above may be executed only when, for example, the instruction input unit 3 receives an instruction from the user to display the waveform.

[0185] The above describes the embodiments. 2 Test apparatus 1 related to this A In this process, the parameter calculation unit 5A calculates the value of the equivalent capacitor Cd based on the equation (equation (19) above) that shows the relationship between the impulse voltage application capacitor Cs and the equivalent capacitor Cd, assuming that the initial value Vcd|t=0 of the voltage Vcd during a predetermined period (analysis period Ta) is equal to the voltage obtained by dividing the charging voltage Vcs of the impulse voltage application capacitor Cs by the impulse voltage application capacitor Cs and the equivalent capacitor Cd, and the measured value information 81 stored in the storage unit 8. According to this, the equivalent capacitor Cd, which is one of the parameters related to the winding 11 under test, can be calculated without performing complex calculations. Furthermore, even if the value of Vcd|t=0 is calculated to deviate from the optimal value due to waveform ringing or the like, since equation (20) does not include Cd, the calculated constants Ld and Rd are less likely to be inappropriate even if the value of Vcd|t=0 is calculated to deviate from the optimal value.

[0186] Furthermore, the parameter calculation unit 5A performs regression analysis using the measured voltage Vcd over a predetermined period (analysis period Ta) to determine the equivalent inductor L d The coefficients of the transient response equation for the voltage Vcd in the equivalent circuit 22, which is composed of the equivalent resistance Rd, the impulse voltage application capacitor Cs, and the current limiting resistor Rs (for example, equation (20) or (22) above), are calculated, and the calculated coefficients are compared with the initial voltage Vcd| t=0 Based on this, the equivalent inductor Ld and equivalent resistance Rd are calculated.

[0187] According to this method, a simpler equivalent circuit is used compared to conventional technology, thus reducing the number of unknowns (equivalent capacitor Cd) by one and lowering the order of the transient response equation (differential equation) in the regression analysis. As a result, even when magnetic saturation occurs or the configuration of the coil under test is complex, it becomes less likely that inappropriate values ​​will be calculated for the equivalent inductor Ld and equivalent resistance Rd.

[0188] Furthermore, the parameter calculation unit 5A may perform regression analysis based on the equation obtained by integrating equation (20) (equation (21) or (22)), as described above. This allows for the removal of the second derivative term included in equation (20), thereby suppressing the influence of noise corresponding to the second derivative value included in the measured voltage Vcd. As for the first derivative term, for example, the influence of noise corresponding to the first derivative value included in the voltage Vcd can be suppressed by performing the smoothing process described above on the measured voltage Vcd (time-series data). In this way, by performing regression analysis based on the equation obtained by integrating equation (20), it becomes possible to calculate the equivalent inductor Ld and equivalent resistance Rd with higher accuracy.

[0189] In Embodiment 2, the transient response equation used in the regression analysis is not limited to equations (21) and (22) obtained by integrating the differential equation representing the temporal change in the voltage Vcd of the equivalent circuit 22 with respect to time, but is instead limited to equations (21) and (22) obtained by definitely integrating equation (20) once with respect to time t from time t=0 to time t=a. For example, the parameter calculation unit 5A may calculate the equivalent inductor Ld and equivalent resistance Rd by performing a regression analysis based on an equation obtained by definitely integrating equation (20) twice with respect to time t from time t=0 to time t=a.

[0190] Furthermore, as described above, the test apparatus 1A according to Embodiment 2 displays the measured waveform 300 and theoretical waveform 310 of the voltage Vcd on the display 70 screen based on the measured waveform data 84 and theoretical waveform data 85. This makes it easy for users to compare measured waveforms with theoretical waveforms, thus making it easier to determine whether the obtained analysis results (parameters) are appropriate.

[0191] <Embodiment 3> Figure 11 shows the configuration of the test apparatus 1B according to Embodiment 3.

[0192] The test apparatus 1B according to Embodiment 3 has an initial value of voltage Vcd| t=0This device differs from the test apparatus 1A of Embodiment 2 in that it calculates multiple data pairs of equivalent inductor Ld, equivalent capacitor Cd, and equivalent resistance Rd by changing the value of , calculates the error between the theoretical waveform and the measured waveform based on each data pair, and uses the data pair corresponding to the theoretical waveform with the smallest error as the analysis result for the winding 11 under test. In other respects, it is the same as the test apparatus 1A.

[0193] As shown in Figure 11, the test apparatus 1B has a parameter calculation unit 5B instead of the parameter calculation unit 5A according to Embodiment 2, and further has an error calculation unit 9.

[0194] In addition to the functions of the parameter calculation unit 5A according to Embodiment 2, the parameter calculation unit 5B has the function of calculating multiple data pairs including equivalent capacitor Cd, equivalent inductor Ld, and equivalent resistance Rd.

[0195] Specifically, the parameter calculation unit 5B calculates the initial value of the voltage Vcd| t=0 Change the initial value of the changed voltage Vcd to multiple different values, Vcd| t=0 For each, the values ​​of the equivalent capacitor Cd, the equivalent inductor Ld, and the equivalent resistance Rd are calculated. For example, the parameter calculation unit 5B calculates the initial values ​​of n different voltages Vcd (where n is an integer of 2 or more) Vcd| t=0 Set the parameters and calculate n sets of data pairs including equivalent capacitor Cd, equivalent inductor Ld, and equivalent resistance Rd.

[0196] The value of the voltage Vcd at time t=0 when the switch SW is turned on (initial value) Vcd| t=0 When this is set to "Vmax", the parameter calculation unit 5B increases or decreases Vmax by a predetermined percentage (hereinafter also referred to as the "correction rate"), for example, to obtain the voltage Vcd value (initial value) Vcd| t=0 Set it to multiple different values.

[0197] Here, "Vmax" may be, for example, the measured voltage Vcd at time t=0, or the maximum value of the smoothed waveform obtained by smoothing the measured voltage Vcd.。

[0198] For example, if n=5, parameter calculation unit 5 B Vcd| t=0 Vcd| is changed in 10% increments from -20% to +20% to obtain five initial values. t=0 You may set this. That is, parameter calculation unit 5 B The five initial values ​​Vcd| are "Vmax×(1.00-0.20)", "Vmax×(1.00-0.10)", "Vmax×1.00", "Vmax×(1.00+0.10)", and "Vmax×(1.00+0.20)". t=0 You may set it to that.

[0199] Note that the initial value Vcd| t=0 You can set them to any mutually distinct values, and are not necessarily limited to the examples above. For example, you don't have to change the correction rate at regular intervals (every 10%). Also, the initial value to set is Vcd| t=0 The number is not limited to "5". Also, the correction rate of Vmax is not limited to the above-mentioned range of -20% to +20%.

[0200] The parameter calculation unit 5B calculates the initial value of the voltage Vcd for each set n (where n is an integer greater than or equal to 2) Vcd| t=0 For each case, the equivalent capacitor Cd value, the equivalent inductor Ld value, and the equivalent resistance Rd value are calculated using the same method as the parameter calculation unit 5A according to Embodiment 2, and n sets of analysis result information (data pairs) 83B_1 to 83B_n are stored in the storage unit 8.

[0201] In the example above, the parameter calculation unit 5B calculates 5 different (n=5) Vcd| t=0 For each of these, data pairs including the equivalent capacitor Cd, equivalent inductor Ld, and equivalent resistance Rd are calculated and stored in the storage unit 8 as analysis result information 83B_1 to 83B_5.

[0202] In the following explanation, if we do not distinguish between components with suffixes attached to their reference codes, such as analysis result information 83B_1 to 83B_n, we will use the reference code without the suffix, such as "analysis result information 83B".

[0203] The waveform generation unit 6 sets the initial value of the voltage Vcd to Vcd| t=0 A theoretical waveform of voltage Vcd is generated for each. That is, the waveform generation unit 6 generates a theoretical waveform for each analysis result information 83B_1 to 83B_n using the same method as in Embodiments 1 and 2, and stores it in the storage unit 8 as theoretical waveform data 85B_1 to 85B_n. In the example above, the waveform generation unit 6 generates theoretical waveform data 85B_1 to 85B_5 for each analysis result information 83B_1 to 83B_5.

[0204] The error calculation unit 9 calculates the error between the theoretical waveform of the voltage Vcd generated by the waveform generation unit 6 and the measured waveform of the voltage Vcd measured by the voltage measurement unit 4. t=0 The above error is calculated for each instance.

[0205] For example, the error calculation unit 9 calculates the error (e.g., squared error) between the theoretical waveform data 85B_1 and the measured waveform data 84 at each unit time during the analysis period Ta, and stores the accumulated value of the calculated error as error data 86_1 in the storage unit 8. Similarly, the error calculation unit 9 calculates the error between the theoretical waveform data 85B_n and the measured waveform data 84 at each unit time, and stores the accumulated value of the calculated error as error data 86_n in the storage unit 8.

[0206] The parameter calculation unit 5B uses the values ​​of the equivalent capacitor Cd, equivalent inductor Ld, and equivalent resistance Rd that minimize the error as the analysis results for the winding 11 under test. For example, the parameter calculation unit 5B uses the initial value of the voltage Vcd| t=0Of the data pairs (analysis result information 83B_1 to 83B_n) containing the equivalent capacitor Cd value, equivalent inductor Ld value, and equivalent resistance Rd value calculated for each test, the data pair with the smallest error is used as the analysis result for the winding 11 under test. A detailed explanation follows using Figures 12 to 15.

[0207] Figure 12 shows the initial value of the voltage Vcd| t=0 This figure shows an example of the error between the theoretical and measured waveforms of voltage Vcd when the voltage is changed.

[0208] Figure 13 shows the initial value of the voltage Vcd| t=0 This figure shows an example of the equivalent inductor Ld when the coefficient is changed.

[0209] Figure 14 shows the initial value of the voltage Vcd| t=0 This figure shows an example of the equivalent capacitor Cd when the coefficient is changed.

[0210] Figure 15 shows the initial value of the voltage Vcd| t=0 This figure shows an example of the equivalent resistance Rd when the coefficient is changed.

[0211] In Figures 12 to 15, the horizontal axis represents the initial value of the voltage Vcd| t=0 This represents the correction rate [%]. In Figure 12, the vertical axis represents the sum (integrated value) of the squared error between the theoretical waveform and the measured waveform of the voltage Vcd per unit time over the analysis period Ta. In Figure 13, the vertical axis represents the equivalent inductor Ld, in Figure 14, the vertical axis represents the equivalent capacitor Cd, and in Figure 15, the vertical axis represents the equivalent resistance Rd.

[0212] The graph of reference numeral 201 in Figure 12 shows the initial value of the voltage Vcd Vcd| t=0The reference value is set to "Vmax," and the graph shows the change in error (sum of squared errors) when the above reference value is corrected (changed) by a predetermined correction rate (-50% to +80%). The graph of reference numeral 202 in Figure 13 shows the change in equivalent inductor Ld when the above reference value is corrected (changed) by a predetermined correction rate (-50% to +80%). The graph of reference numeral 203 in Figure 14 shows the change in equivalent capacitor Cd when the above reference value is corrected (changed) by a predetermined correction rate (-50% to +80%). The graph of reference numeral 204 in Figure 15 shows the change in equivalent resistance Rd when the above reference value is corrected (changed) by a predetermined correction rate (-50% to +80%).

[0213] From the graph of reference numeral 201 in Figure 12, the initial value of the voltage Vcd when the correction rate is approximately "-3.3%" is Vcd| t=0 It is understood that the error is minimized in this case.

[0214] Therefore, when the point where the error is minimized (the minimum error point) is defined as "Q", the parameter calculation unit 5B uses a data pair (analysis result information 83B) that includes the value of the equivalent capacitor Cd, the value of the equivalent inductor Ld, and the value of the equivalent resistance Rd at the minimum error point Q as the analysis result of the winding 11 under test.

[0215] In the example described above, the parameter calculation unit 5B uses analysis result information 83B, which includes the equivalent inductor Ld value Ld_q in Figure 13, the equivalent capacitor Cd value Cd_q in Figure 14, and the equivalent resistance Rd value Rd_q in Figure 15, as the analysis result of the winding 11 under test. In this way, the analysis result information 83 selected by the parameter calculation unit 5B is displayed on the display 70 of the display unit 7 as, for example, the analysis result information of the winding 11 under test.

[0216] The display unit 7 may also display at least one of the graphs (201 to 204) shown in Figures 13 to 15 on the display 70.

[0217] Next, we will explain the procedure for analyzing the winding 11 to be tested using the test apparatus 1B according to Embodiment 3.

[0218] Figure 16 is a flowchart showing the flow of the analysis method for the winding 11 using the test apparatus 1B according to Embodiment 3.

[0219] In the flowchart shown in Figure 16, the processes from step S1 to step S9A are the same as those in the flowchart according to Embodiment 2 (Figure 10).

[0220] After step S9A, the error calculation unit 9 calculates the initial value of the voltage Vcd generated in step S9A using the method described above, Vcd| t=0 The error between the theoretical waveform data 85 and the measured waveform data 84 when the value is "Vmax" is calculated and stored in the storage unit 8 as error data 86 (step S10B).

[0221] Next, the parameter calculation unit 5 B The initial value of the voltage Vcd is Vcd| t=0 Step S11B determines whether the process of changing the correction factor to calculate the equivalent capacitor Cd, equivalent inductor Ld, and equivalent resistance Rd, and calculating the error between the measured waveform and the theoretical waveform (steps S8A to S10B) has been performed a predetermined number of times. Here, the predetermined number of times, i.e., the number of times the correction factor has been changed, may be set in advance in the storage unit 8, or it may be set by the user operating the test device 1B before performing the analysis of the winding 11.

[0222] If the above process (steps S8A to S10B) has not been executed a predetermined number of times (step S11B: NO), the parameter calculation unit 5 B The initial value of the voltage Vcd, Vcd|t = 0, is changed according to the correction rate using the method described above (step S12B). Next, the parameter calculation unit 5B, the waveform generation unit 6, and the error calculation unit 9 execute steps S8A to S10B using the initial value of the voltage Vcd, Vcd|t = 0, which was changed in step S12B.

[0223] When the above processing (steps S8A to S10B) has been executed a predetermined number of times (step S11B: YES), the parameter calculation unit 5 B , by the method described above, among the plurality of analysis result information 83B_1 to 83B_n including the equivalent capacitor Cd, equivalent inductor Ld, and equivalent resistor Rd calculated by changing t=0 the initial value Vcd| of the voltage Vcd, selects the analysis result information 83 with the smallest error as the analysis result of the winding 11 to be tested (step S13B).

[0224] Next, the display unit 7 causes the parameter calculation unit 5 in step S13 B to display information related to the selected analysis result information 83 (step S14B). For example, the display unit 7 may cause the parameter calculation unit 5 in step S13 B to display the respective values of the equivalent capacitor Cd, equivalent inductor Ld, and equivalent resistor Rd included in the selected analysis result information 83 on the screen of the display 70.

[0225] Further, for example, similarly to the test apparatus 1 according to the first embodiment, the display unit 7 may cause the parameter calculation unit 5 in step S13 B to display the theoretical waveform based on the selected analysis result information 83 and the measured waveform together on the display 70. Further, the display unit 7 may display at least one of the graphs denoted by reference numerals 201 to 204 in FIGS. 12 to 15 on the display 70.

[0226] Note that the information displayed by the display unit 7 in step S14B may be information specified by the user via the instruction input unit 3, similarly to the test apparatus 1 according to the first embodiment.

[0227] As described above, in the test apparatus 1B according to the third embodiment, the parameter calculation unit 5B changes the initial value Vcd| of the voltage Vcd t=0 to a plurality of mutually different values, and for each changed initial value Vcd| of the voltage Vcd t=0 calculates the value of the equivalent capacitor Cd, the value of the equivalent inductor Ld, and the value of the equivalent resistor Rd. The error calculation unit 9 calculates, for each changed initial value Vcd| of the voltage Vcdt=0 For each step, the error between the theoretical waveform of voltage Vcd and the measured waveform of voltage Vcd is calculated. The parameter calculation unit 5B calculates the initial value of voltage Vcd| t=0 Of the data pairs (analysis result information 83B_1~83B_n) containing the equivalent capacitor Cd value, equivalent inductor Ld value, and equivalent resistance Rd value calculated for each test, the data pair with the smallest error is used as the analysis result for the winding 11 under test.

[0228] According to this method, even when parameters (data pairs) related to the winding 11 under test are calculated using a simpler regression analysis compared to conventional techniques, the data pair that results in the theoretical waveform closest to the measured voltage Vcd is searched for, enabling more accurate analysis of the winding 11.

[0229] Furthermore, the method for calculating the analysis results is not limited to the examples described above. For example, for error data 86_1 to 86_n, approximate quadratic curves can be obtained for each point plotted with the correction rate on the x-axis and the error and Cd, Ld, and Rd on the y-axis. Next, the correction rate that minimizes the error value on the approximate quadratic curve of the error can be found. Then, the correction rate that minimizes the error value can be substituted into the approximate quadratic curves of Cd, Ld, and Rd, and the resulting values ​​of Cd, Ld, and Rd can be used as the analysis results. Alternatively, an approximate value of the correction rate that minimizes the error value can be found using a known recursive algorithm, and the analysis results can be obtained from that approximate value of the correction rate in the same manner as described above.

[0230] <<Extension of the Embodiment>> Although the invention made by the present inventor has been specifically described above based on embodiments, it goes without saying that the present invention is not limited thereto and can be modified in various ways without departing from its essence.

[0231] For example, in the above embodiment, the case in which the test apparatus 1 is equipped with a reverse current prevention diode D was illustrated, but the test apparatus 1 does not necessarily have to be equipped with a reverse current prevention diode D.

[0232] Furthermore, while embodiments 2 and 3 illustrate the case where the timing of turning on the switch SW is set to time t=0 in the analysis period Ta, the invention is not limited to this. For example, when using time-series data obtained by smoothing the time-series data of voltage Vcd measured by the voltage measurement unit 4 using a moving average window for regression analysis, the rising time of the smoothed waveform and the time when the switch SW is turned on may differ. Also, the time when the smoothed waveform reaches its maximum value may differ from the time when the switch SW is turned on.

[0233] In such cases, for example, the calculation may be performed by interpolating from the rising edge time of the smoothed waveform to the time when the smoothed waveform reaches its maximum value, so that the smoothed waveform is Vcd with the correction factor applied at the time the switch SW is turned ON.

[0234] Furthermore, the flowchart described above is merely an example illustrating the operation and is not limited to it. In other words, the steps shown in each diagram of the flowchart are specific examples and are not limited to this flow. For example, the order of some processes may be changed, other processes may be inserted between each process, or some processes may be performed in parallel. [Explanation of Symbols]

[0235] 1, 1A, 1B... Test device, 2... Impulse voltage generation circuit, 3... Instruction input unit, 4... Voltage measurement unit, 5, 5A, 5B... Parameter calculation unit, 6... Waveform generation unit, 7... Display unit, 8... Memory unit, 9... Error calculation unit, 20~22... Equivalent circuit, 81... Measured value information, 82... Formula information, 83, 83B_1~83B_n... Analysis result information, 84... Measured waveform data, 85, 85B_1~85B_n... Theoretical waveform data, 86_1~86_n... Error data, C s...Capacitor for applying impulse voltage, Cd...Equivalent capacitor on winding 11, Ld...Equivalent inductor on winding 11, Rd...Equivalent resistance on winding 11, Rs...Current limiting resistor, D...Rectifier element (reverse current prevention diode), E...Impulse voltage, Ta...Analysis period, Pmax...Maximum point, Pmin...Minimum point, T1...External terminal (1st external terminal), T2...External terminal (2nd external terminal), 70...Display, 300...Measured waveform, 310...Theoretical waveform.

Claims

1. A first external terminal to which one terminal of the winding under test is connected, and a second external terminal to which the other terminal of the winding is connected, A capacitor for applying an impulse voltage, with 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, A current limiting resistor connected in series with the switch is placed between the other end of the impulse voltage application capacitor and the first external terminal. An instruction input unit that receives instructions to start the test, A voltage measuring unit for measuring the voltage between the first external terminal and the second external terminal, A storage unit that stores measurement information including the measured voltage measured by the voltage measuring unit, The winding is represented equivalently 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, and the parameter calculation unit calculates at least one of the values ​​of the equivalent inductor, the equivalent capacitor, and the equivalent resistor based on the measurement information stored in the storage unit. The instruction input unit turns on the switch in response to the instruction to start the test. The parameter calculation unit, By performing a regression analysis on the predetermined period using the measured voltage values ​​from the measurement data stored in the memory unit, during the period from when the switch is turned on until resonance based on the equivalent inductor, equivalent capacitor, and equivalent resistance of the winding begins, at least one of the equivalent capacitor value, the equivalent inductor value, and the equivalent resistance value is calculated. Testing equipment.

2. In the test apparatus described in claim 1, The other end of the impulse voltage application capacitor and the first external terminal are further connected in series with the switch and the current limiting resistor, and the rectifier element allows current to pass from the impulse voltage application capacitor side to the first external terminal side and blocks current from the first external terminal side to the impulse voltage application capacitor side. A test apparatus characterized by the following features.

3. In the test apparatus according to claim 1 or 2, The parameter calculation unit detects the maximum point where the voltage is highest and the minimum point where the voltage is lowest after the switch is turned on, and sets the period between the maximum point and the minimum point as the predetermined period. A test apparatus characterized by the following features.

4. In the test apparatus according to any one of claims 1 to 3, The parameter calculation unit performs regression analysis using the measured voltage values ​​over a predetermined period to calculate the coefficients of the equation for the transient response of the voltage in the equivalent circuit composed of the equivalent inductor, the equivalent capacitor, the equivalent resistance, the impulse voltage application capacitor, and the current limiting resistor. Based on the calculated coefficients, it calculates the value of the equivalent capacitor, the value of the equivalent inductor, and the equivalent resistance. A test apparatus characterized by the following features.

5. In the test apparatus described in claim 4, The transient response equation is obtained by integrating the differential equation representing the time change of the voltage in the equivalent circuit multiple times with respect to time. A test apparatus characterized by the following features.

6. In the test apparatus described in claim 5, The transient response equation is obtained by integrating the differential equation three times with respect to time, 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 voltage between the first external terminal and the second external terminal is Vcd, and time is t, the equation obtained by the three integrations is expressed by the following equation (1). A test apparatus characterized by the following features. [Math 1]

7. In the test apparatus described in claim 5, The transient response equation is obtained by integrating the differential equation twice with respect to time, 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 voltage between the first external terminal and the second external terminal is Vcd, and time is t, the equation obtained by integrating twice is expressed by the following equation (2). A test apparatus characterized by the following features. [Math 2]

8. In the test apparatus according to any one of claims 4 to 7, A waveform generation unit generates a theoretical voltage waveform by numerically integrating using the transient response equation to which the equivalent capacitor value, the equivalent inductor value, and the equivalent resistance value calculated by the parameter calculation unit are applied. The system further includes a display unit that displays the theoretical waveform generated by the waveform generation unit and the measured waveform of the voltage measured by the voltage measurement unit. Testing equipment.

9. In the test apparatus according to claim 1 or 2, The parameter calculation unit calculates the value of the equivalent capacitor based on an equation showing the relationship between the impulse voltage application capacitor and the equivalent capacitor, assuming that the initial value of the voltage during the predetermined period matches the voltage obtained by dividing the charging voltage of the impulse voltage application capacitor by the impulse voltage application capacitor and the equivalent capacitor, and the measured value information stored in the storage unit. The parameter calculation unit performs regression analysis using the measured voltage values ​​over a predetermined period to calculate the coefficients of the equation for the transient response of the voltage in the equivalent circuit composed of the equivalent inductor, the equivalent resistance, the impulse voltage application capacitor, and the current limiting resistor. Based on the calculated coefficients and the initial voltage value, it calculates the values ​​of the equivalent inductor and the equivalent resistance. A test apparatus characterized by the following features.

10. In the test apparatus described in claim 9, A waveform generation unit generates a theoretical voltage waveform by numerically integrating using the transient response equation to which the equivalent capacitor value, the equivalent inductor value, and the equivalent resistance value calculated by the parameter calculation unit are applied. The system further includes an error calculation unit that calculates the error between the theoretical waveform generated by the waveform generation unit and the measured voltage waveform measured by the voltage measurement unit, The parameter calculation unit uses the values ​​of the equivalent capacitor, the equivalent inductor, and the equivalent resistance that minimize the error as the winding analysis results. A test apparatus characterized by the following features.

11. In the test apparatus according to claim 9 or 10, The transient response equation is obtained by integrating the differential equation representing the time change of the voltage in the equivalent circuit with respect to time. A test apparatus characterized by the following features.

12. In the test apparatus according to claim 11, 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 voltage between the first external terminal and the second external terminal is Vcd, and time is t, the transient response equation is obtained by integrating the differential equation from time t=0 to time t=a (a>0). The resulting equation is expressed by the following equation (3). A test apparatus characterized by the following features. [Math 3]

13. A test method using a test apparatus comprising: a first external terminal to which one terminal of the winding under test is connected; a second external terminal to which the other terminal of the winding is connected; an impulse voltage application capacitor with 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, wherein The first step is to turn on the aforementioned switch, A second step of measuring the voltage between the first external terminal and the second external terminal, A third step involves storing measurement information, including the measured voltage, measured in the second step, The fourth step includes calculating at least one of the values ​​of the equivalent inductor, the equivalent capacitor, and the equivalent resistor, 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, based on the measured value information stored in the third step. The fourth step is, The third step includes a step of calculating at least one of the equivalent capacitor value, the equivalent inductor value, and the equivalent resistance value by performing a regression analysis over a predetermined period using the measured voltage values ​​from the stored measured value information in the third step, during the period from when the switch is turned on until resonance based on the equivalent inductor, equivalent capacitor, and equivalent resistance of the winding begins. Test method.

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