JP2021001765A - Electrostatic capacitance measurement device, deterioration diagnosis device, electrostatic capacitance measurement method, deterioration diagnosis method, and electrostatic capacitance measurement program - Google Patents

Abstract

To readily calculate an electrostatic capacitance of a capacitor.SOLUTION: An electrostatic capacitance measurement device (10) comprises: an input unit (110) that inputs a voltage measurement value of a capacitor (2), and a current measurement value of the capacitor (2); a voltage change rate measurement unit (120) that measures a first voltage change rate of a voltage of the capacitor (2) at a prescribed time from the voltage measurement value of the capacitor (2); and a calculation unit (130) that calculates an electrostatic capacitance of the capacitor (2) from at least the voltage measurement value, current measurement value, and first voltage change rate at the prescribed time.SELECTED DRAWING: Figure 1

Description

The present invention relates to a capacitance measuring device, a deterioration diagnostic device, a capacitance measuring method, a deterioration diagnostic method, and a capacitance measuring program.

A capacitance measuring device for measuring the capacitance of a capacitor is known as a prior art. For example, Patent Document 1 discloses a device including a measuring device for measuring a characteristic value such as a capacitance of a capacitor. The device stores the characteristic values of the capacitors measured by the measuring instrument in the database.

Japanese Unexamined Patent Publication No. 2004-37258 (published on February 5, 2004)

Patent Document 1 does not disclose details of a method for measuring the capacitance of a capacitor. Therefore, the apparatus disclosed in Patent Document 1 has room for further improvement in the method of measuring the capacitance of the capacitor. One aspect of the present invention is to easily calculate the capacitance of a capacitor.

In order to solve the above-mentioned problems, the capacitance measuring device according to one aspect of the present invention is an input for inputting a voltage measurement value of a voltage applied to a capacitor and a current measurement value of a current flowing through the capacitor. A voltage change rate measuring unit that measures the first voltage change rate of the voltage applied to the capacitor at a predetermined time point from the voltage measurement value input by the input unit and the input unit, and the input unit. With reference to the voltage measurement value and the current measurement value, at least from the voltage measurement value and the current measurement value at the predetermined time point, and the first voltage change rate measured by the voltage change rate measuring unit. It is provided with a calculation unit for calculating the capacitance of the capacitor.

According to the above configuration, the capacitance of the capacitor can be easily calculated by using the measured voltage value, the measured current value, and the voltage change rate of the capacitor. Therefore, a capacitance measuring device for measuring the capacitance of a capacitor can be realized at low cost.

The voltage change rate measuring unit measures the first voltage change rate at two time points as the predetermined time points, and the calculating unit measures the voltage measured value and the current measured value at the two time points. The capacitance of the capacitor may be calculated from the first voltage change rate at the two time points measured by the voltage change rate measuring unit. According to the above configuration, the capacitance of the capacitor can be easily calculated by referring to each value for calculating the capacitance of the capacitor at two time points.

The period between the two time points may be less than or equal to a predetermined period. According to the above configuration, for example, the period between the two time points is set to be equal to or less than a predetermined period so that the change of each value for calculating the capacitance of the capacitor becomes small at the two time points. As a result, the accuracy of calculating the capacitance of the capacitor can be improved.

The capacitance measuring device further includes a current change rate measuring unit for measuring the current change rate of the current flowing through the capacitor at a predetermined time point from the current measured value input by the input unit, and further includes a voltage change measuring unit. The rate measuring unit further measures the second voltage change rate, which is a value obtained by differentiating the first voltage change rate, and the calculating unit further measures the voltage measured value and the current measured value at the predetermined time point, and the said. In addition to the first voltage change rate measured by the voltage change rate measuring unit, the second voltage change rate measured by the voltage change rate measuring unit, and the current change rate measuring unit measured by the current change rate measuring unit. The electrostatic capacity of the capacitor may be calculated from the current change rate.

According to the above configuration, the capacitance of the capacitor is calculated using the second voltage change rate, which is the differentiated value of the first voltage change rate. For example, when the second voltage change rate is obtained by approximation, more information is used than when the first voltage change rate is obtained. Therefore, by calculating the capacitance of the capacitor using the second voltage change rate, the accuracy of calculating the capacitance of the capacitor can be improved.

In order to solve the above-mentioned problems, the deterioration diagnosis device according to one aspect of the present invention includes an input unit for inputting a voltage measurement value of a voltage applied to the capacitor and a current measurement value of a current flowing through the capacitor. , The voltage change rate measuring unit that measures the voltage change rate of the voltage applied to the capacitor at a predetermined time from the voltage measured value input by the input unit, and the voltage measured value input by the input unit. And the electrostatic capacity of the capacitor from at least the voltage measurement value and the current measurement value at the predetermined time point, the voltage change rate measured by the voltage change rate measuring unit, and the current measurement value. And the calculation unit that calculates the admittance of the leakage current, the amount of decrease in the capacitance of the capacitor calculated by the calculation unit from the initial value, and the leakage current of the capacitor calculated by the calculation unit in the admittance. It includes an amount of increase from the initial value and a result output unit that outputs the result of the deterioration diagnosis of the capacitor.

According to the above configuration, for each of a wide variety of capacitors, the deterioration diagnosis of the capacitor can be easily performed without constructing a database for diagnosing the characteristics of the capacitor which is a reference for diagnosis and the deterioration of the capacitor. Therefore, as compared with the case of constructing the database, it is possible to realize a deterioration diagnosis device for performing deterioration diagnosis of a capacitor at a low cost.

The result output unit may further output the result of life prediction of the capacitor from the decrease amount and the increase amount. According to the above configuration, in addition to the result of the deterioration diagnosis of the capacitor, the result of the life prediction of the capacitor can be confirmed.

In order to solve the above problems, the electrostatic capacity measuring method according to one aspect of the present invention includes a voltage measuring step of measuring a voltage applied to a capacitor as a voltage measured value and a current measuring value of the current flowing through the capacitor. The voltage change rate measuring step for measuring the voltage change rate of the voltage applied to the capacitor at a predetermined time point from the voltage measured value measured in the voltage measuring step, and the voltage change rate measuring step. With reference to the voltage measurement value and the current measurement value measured in each of the measurement step and the current measurement step, at least the voltage measurement value and the current measurement value at the predetermined time point, and the voltage change rate measurement. It includes a calculation step of calculating the capacitance of the capacitor from the voltage change rate measured in the step.

In order to solve the above problems, the deterioration diagnosis method according to one aspect of the present invention includes a voltage measuring step of measuring the voltage applied to the capacitor as a voltage measurement value and measuring the current flowing through the capacitor as a current measurement value. A voltage change rate measuring step for measuring the voltage change rate of the voltage applied to the capacitor at a predetermined time point from the voltage measured value measured in the voltage measuring step, and the voltage measuring step. With reference to the voltage measurement value and the current measurement value measured in each of the current measurement steps, at least the voltage measurement value and the current measurement value at the predetermined time point, and the voltage change rate measurement step. The calculation step of calculating the admittance of the capacitance and the leakage current of the capacitor from the measured voltage change rate, and the amount of decrease in the capacitance of the capacitor calculated in the calculation step from the initial value. And the result output step of outputting the result of the deterioration diagnosis of the capacitor from the amount of increase from the initial value in the admittance of the leakage current of the capacitor calculated in the calculation step.

In order to solve the above-mentioned problems, the capacitance measurement program according to one aspect of the present invention is a capacitance measurement program for operating a computer as the capacitance measurement device, and the input unit, the said. It may be for making a computer function as a voltage change rate measuring unit and the calculation unit.

According to one aspect of the present invention, the capacitance of the capacitor can be easily calculated.

It is a block diagram which shows the structure of the vehicle which includes the capacitance measuring apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the equivalent circuit with respect to the capacitor provided in the power conversion device provided in the vehicle shown in FIG. It is a graph which shows the measurement result of the voltage and the current of a capacitor in the experimental example concerning the processing of the calculation part of the capacitance measuring apparatus included in the vehicle shown in FIG. It is a graph which shows the calculation result of the admittance of the capacitance and the leakage current of a capacitor in the experimental example concerning the processing of a calculation part. From the graph shown in FIG. 4, the horizontal axis is changed from time to an electric field. It is a block diagram which shows the structure of the product inspection apparatus which includes the capacitance measuring apparatus which concerns on Embodiment 1 of this invention. It is a block diagram which shows the structure of the vehicle which includes the capacitance measuring apparatus which concerns on Embodiment 2 of this invention.

[Embodiment 1]
(Configuration of Capacitance Measuring Device 10)
The configuration of the capacitance measuring device 10 will be described with reference to FIG. FIG. 1 is a block diagram showing a configuration of a vehicle V1 including the capacitance measuring device 10 according to the first embodiment of the present invention. A vehicle V1 such as an HEV (Hybrid Electric Vehicle) or an EV (Electric Vehicle) is provided with a power conversion device E1 as shown in FIG.

The power conversion device E1 is a device that converts power between direct current and alternating current. The power conversion device E1 includes a deterioration diagnosis device 1, a capacitor 2, a voltmeter 3, an ammeter 4, and a storage unit 5. The deterioration diagnosis device 1 is connected to a capacitor 2, a voltmeter 3, an ammeter 4, and a storage unit 5. The capacitor 2 is connected in parallel with the voltmeter 3 and is connected in series with the ammeter 4. The voltmeter 3 and the ammeter 4 may be outside the power conversion device E1 and may be provided in the vehicle V1.

As the capacitor 2, for example, a film capacitor is preferably used. A film capacitor is constructed by depositing metal on a plastic film and winding it. Compared with ceramic capacitors and electrolytic capacitors, film capacitors have the characteristics of being able to handle high voltages, having good high-frequency characteristics, and having less dielectric loss.

For this reason, film capacitors are widely used in electronic applications, in-vehicle applications, and industrial applications. As described above, by using the film capacitor as the capacitor 2 of the power conversion device E1 included in the vehicle V1, it is possible to cope with a high voltage, improve the high frequency characteristics, and reduce the dielectric loss.

The voltmeter 3 measures the voltage applied to the capacitor 2 as a voltage measurement value (voltage measurement step). The voltmeter 3 provides the voltage measurement value obtained by the measurement to the deterioration diagnosis device 1. The ammeter 4 measures the current flowing through the capacitor 2 as a current measurement value (current measurement step). The ammeter 4 provides the deterioration diagnosis device 1 with the current measurement value obtained by the measurement.

The deterioration diagnosis device 1 is a device that performs deterioration diagnosis of the capacitor 2. When the deterioration diagnosis device 1 is provided in the vehicle V1, the deterioration diagnosis device 1 performs deterioration diagnosis of the capacitor 2 during the operation of the vehicle V1. The deterioration diagnosis device 1 may be provided in an industrial machine other than the vehicle V1. The deterioration diagnosis device 1 includes a capacitance measuring device 10 and a result output unit 140. The capacitance measuring device 10 is a device for measuring the capacitance of the capacitor 2. The capacitance measuring device 10 includes an input unit 110, a voltage change rate measuring unit 120, and a calculating unit 130.

The input unit 110 inputs the voltage measurement value provided by the voltmeter 3 to the deterioration diagnosis device 1 and the current measurement value provided by the ammeter 4 to the deterioration diagnosis device 1. In other words, the input unit 110 inputs a voltage measurement value of the voltage applied to the capacitor 2 and a current measurement value of the current flowing through the capacitor 2. The input unit 110 stores the input voltage measurement value and current measurement value in the storage unit 5.

The voltage change rate measuring unit 120 measures the first voltage change rate (voltage change rate) of the voltage applied to the capacitor 2 at a predetermined time point from the voltage measured value input by the input unit 110 (voltage change rate measurement). Process). The first voltage change rate is, for example, a value obtained by first-order differentiation of the voltage applied to the capacitor 2 at a predetermined time point. At this time, the voltage change rate measuring unit 120 refers to the voltage measured value stored in the storage unit 5. The voltage change rate measuring unit 120 stores the measured first voltage change rate in the storage unit 5. The predetermined time point is appropriately determined by the user who uses the deterioration diagnosis device 1. Details of the predetermined time point will be described later.

The calculation unit 130 refers to the voltage measurement value and the current measurement value input by the input unit 110. Further, the calculation unit 130 uses the voltage measurement value and the current measurement value at the predetermined time point, the first voltage change rate measured by the voltage change rate measurement unit 120, and the admittance of the capacitance and the leakage current of the capacitor 2. Is calculated. At this time, the calculation unit 130 refers to the voltage measurement value, the current measurement value, and the first voltage change rate stored in the storage unit 5. The calculation unit 130 stores the calculated admittance of the capacitance and leakage current of the capacitor 2 in the storage unit 5.

In the second embodiment described later, the calculation unit 130A includes a second voltage change rate and a current change rate in addition to the voltage measurement value and the current measurement value at the predetermined time point and the first voltage change rate. From ,, the admittance of the capacitance and the leakage current of the capacitor 2 is calculated.

Therefore, the calculation unit according to one aspect of the present invention includes at least the voltage measurement value and the current measurement value at the predetermined time point, the first voltage change rate measured by the voltage change rate measurement unit 120, and the capacitor 2. Calculate the admittance of capacitance and leakage current (calculation process). According to the above configuration, the capacitance of the capacitor 2 can be easily calculated by using the voltage measurement value, the current measurement value, and the first voltage change rate of the capacitor 2. Therefore, the capacitance measuring device 10 for measuring the capacitance of the capacitor 2 can be realized at low cost.

(Details of processing of calculation unit 130)
In the calculation process of the admittance of the capacitance and the leakage current of the capacitor 2 in the calculation unit 130, the equivalent circuit shown in FIG. 2 is considered for the capacitor 2 which is the target of the deterioration diagnosis. FIG. 2 is a diagram showing an equivalent circuit for a capacitor 2 provided in the power conversion device E1 included in the vehicle V1 shown in FIG. As shown in FIG. 2, consider a case where a current I is passed through the capacitor 2 from the outside of the capacitor 2.

In this case, the current I is the current measured by the ammeter 4. Further, a leakage current I2 is generated in the capacitor 2. The current obtained by subtracting the leakage current I2 from the current I is defined as the current I1. That is, the current I is equal to the sum of the current I1 and the current I2. Here, the capacitance of the capacitor 2 is C, and the admittance of the leakage current I2 of the capacitor 2 is Y. The admittance Y is a parallel admittance with the capacitor 2, and is an admittance of the leakage current I2.

Further, there are two time points, that is, a time point (t-a second) that is a second backward from a certain point (t second) and a time point (t + a second) that is a second forward from a certain point (t second). Consider the case of a time point. In this case, the calculation unit 130 measures the voltage measurement value V (ta), the current measurement value I (ta), and the current measurement value I (ta) in ta seconds in order to calculate the capacitance C and the admittance Y of the capacitor 2. The first voltage change rate dV (ta) / dt is used.

Further, the calculation unit 130 uses the voltage measurement value V (t + a) at t + a seconds, the current measurement value I (t + a), and the first voltage change rate dV (t + a) / dt. At this time, the voltage change rate measuring unit 120 measures the first voltage change rates dV (ta) / dt and dV (t + a) / dt at the two time points as the predetermined time points. When the calculation unit 130 uses these values, simultaneous equations including the following equations (1) and (2) can be obtained from the equivalent circuit shown in FIG.

The simultaneous equations are regarded as quadratic linear simultaneous equations, and the voltage measurement value and the first voltage change rate at the two time points are regarded as the coefficients of the simultaneous equations. Further, the current measurement values at the two time points are regarded as known variables, and the capacitance and the attitude of the capacitor 2 are regarded as unknown variables. As a result, the following equation (3) is obtained.

When the simultaneous equations are constructed in this way, as shown in the following equation (4), the calculation unit 130 performs a simple 2-by-2 inverse matrix calculation, and the capacitance of the capacitor 2 at a certain time point (t seconds). Capacitance C and admittance Y can be calculated. That is, the calculation unit 130 performs the calculation processing of the formulas (1) to (4) to calculate the capacitance C and the admittance Y of the capacitor 2 at a certain time point (t seconds).

As described above, the calculation unit 130 includes the voltage measurement value and the current measurement value at the two time points, the first voltage change rate at the two time points measured by the voltage change rate measurement unit 120, and the capacitor 2. The admittance Y of the capacitance C and the leakage current I2 is calculated. According to the configuration, the capacitance C of the capacitor 2 and the leakage current I2 are referred to at each of the values for calculating the admittance Y of the capacitance C and the leakage current I2 at the two time points. The admittance Y can be easily calculated.

Further, the period (2a seconds) between the time point (t-a seconds) and the time point (t + a seconds) is preferably a predetermined period or less. In other words, the period between the two time points is preferably not more than a predetermined period. According to the configuration, for example, between the two time points, the change in each value for calculating the admittance Y of the capacitance C and the leakage current I2 of the capacitor 2 becomes small at the two time points. The period is set to be less than or equal to the predetermined period. As a result, the accuracy of calculating the admittance Y of the capacitance C of the capacitor 2 and the leakage current I2 can be improved.

The result output unit 140 refers from the storage unit 5 to the admittance Y of the capacitance C of the capacitor 2 and the leakage current I2 calculated by the calculation unit 130. The result output unit 140 outputs the result of the deterioration diagnosis of the capacitor 2 from the amount of decrease from the initial value in the capacitance C of the capacitor 2 and the amount of increase in the admittance Y of the leakage current I2 of the capacitor 2 from the initial value. (Result output process).

According to the above configuration, deterioration diagnosis of the capacitor 2 can be easily performed for each of a wide variety of capacitors 2 without constructing a database for diagnosing the characteristics of the capacitor 2 as a reference for diagnosis and the deterioration of the capacitor 2. be able to. Therefore, as compared with the case of constructing the database, the deterioration diagnosis device 1 for performing the deterioration diagnosis of the capacitor 2 can be realized at low cost.

Further, the result output unit 140 is the result of life prediction of the capacitor 2 from the amount of decrease from the initial value in the capacitance C of the capacitor 2 and the amount of increase in the admittance Y of the leakage current I2 of the capacitor 2 from the initial value. May be output further. According to the above configuration, in addition to the result of the deterioration diagnosis of the capacitor 2, the result of the life prediction of the capacitor 2 can be confirmed. In addition to this, it is possible to easily predict the life of the capacitor 2 without constructing a database for predicting the life of the capacitor 2.

The initial value of the capacitance C of the capacitor 2 is determined as the rated value of the capacitor 2. Further, the initial value of the admittance Y of the capacitor 2 is determined by the rated value of the leakage current I2 of the capacitor 2. Therefore, even if there are various types of capacitors 2, the initial values of the capacitance C and admittance Y of the capacitors 2 are determined by the rated values. Therefore, the deterioration diagnosis and the life prediction of the capacitor 2 can be easily performed from the amount of decrease from the initial value in the capacitance C and the amount of increase from the initial value in admittance Y.

In the result output unit 140, the ratio of the amount of decrease from the initial value in the capacitance C of the capacitor 2 and the ratio of the amount of increase in the admittance Y of the leakage current I2 of the capacitor 2 from the initial value, and so on. The result of deterioration diagnosis and the result of life prediction may be output. The ratio of the amount of decrease in the capacitance C from the initial value is the ratio of the amount of decrease when the initial value is 100%. The ratio of the amount of increase from the initial value in admittance Y is the ratio of the amount of increase when the initial value is 100%.

In the result output unit 140, if the ratio of the amount of decrease from the initial value in the capacitance C is equal to or greater than the first predetermined value and the proportion of the amount of increase from the initial value in admittance Y is equal to or greater than the second predetermined value. , The result of the deterioration diagnosis may be output assuming that the capacitor 2 is deteriorated. The result output unit 140 may sequentially output the result of the deterioration diagnosis of the capacitor 2 and the result of the life prediction during the operation of the vehicle V1.

(Experimental example)
Next, an experimental example relating to the processing of the calculation unit 130 will be described with reference to FIGS. 3 to 5. In this experimental example, a high voltage was applied to the capacitor using a high voltage DC power supply, and the voltage and current of the capacitor were measured. As the capacitor to be evaluated, a film capacitor in which aluminum is vapor-deposited on a polypropylene film having an electrode area of 1 m ² and a thickness of 4 μm and wound is used. The voltage and current were measured with a logger, and the measured data were calculated as spreadsheet software, for example, using a spreadsheet to calculate the capacitance and admittance.

FIG. 3 is a graph showing the measurement results of the voltage and current of the capacitor 2 in the experimental example relating to the processing of the calculation unit 130 of the capacitance measuring device 10 included in the vehicle V1 shown in FIG. In FIG. 3, the horizontal axis is time [seconds], the vertical axis on the left side is voltage [V], and the vertical axis on the right side is current [A]. Further, VN indicates a voltage and IN indicates a current.

FIG. 4 is a graph showing the calculation results of the admittance Y of the capacitance C of the capacitor 2 and the leakage current I2 in the experimental example relating to the processing of the calculation unit 130. Specifically, the graph G1 is a graph showing the calculation result of the capacitance C of the capacitor 2, and the graph G2 is a graph showing the calculation result of the admittance Y of the leakage current I2 of the capacitor 2.

In graph G1, the horizontal axis is time [seconds] and the vertical axis is capacitance [F]. In graph G2, the horizontal axis is time [seconds] and the vertical axis is admittance [S]. Graph G1 and graph G2 are graphs created by calculation using the above-mentioned equations (1) to (4).

FIG. 5 is a graph in which the horizontal axis is changed from time to an electric field from the graph shown in FIG. Specifically, the graph G3 is a graph in which the horizontal axis is changed from time to an electric field from the graph G1, and the graph G4 is a graph in which the horizontal axis is changed from time to an electric field from the graph G2. In the graph G3, the horizontal axis is the electric field [V / μm], and the vertical axis is the capacitance [F]. In the graph G4, the horizontal axis is the electric field [V / μm] and the vertical axis is the admittance [S].

The change from time to electric field is made using the relationship between time and electric field. The voltage of the graph shown in FIG. 3 is divided by the thickness of the polypropylene film (4 μm) to obtain the electric field of the graph shown in FIG. Therefore, the relationship between time and electric field can be obtained from the graph shown in FIG. 3 and the thickness of the polypropylene film. The electric field shown in FIG. 5 causes stress on the capacitor.

The result output unit 140 outputs the result of the deterioration diagnosis of the capacitor 2 and the result of the life prediction with reference to the graph as shown in FIG. That is, the result output unit 140 refers to the relationship between the electric field of the capacitor 2 and the capacitance C and the relationship between the electric field of the capacitor 2 and the admittance Y, and determines the result of deterioration diagnosis of the capacitor 2 and the life prediction. Output the result.

Capacitance and admittance can be calculated from a simple voltage waveform and current waveform as shown in FIG. 3, and deterioration diagnosis and life prediction of a capacitor can be easily performed by the amount of decrease in capacitance and the amount of increase in admittance. be able to.

Here, the predetermined time point is appropriately determined by the user who uses the deterioration diagnosis device 1 as described above. For example, suppose the user assumes that the electric field as stress on the capacitor is 450 V / μm. In this case, since the thickness of the polypropylene film is 4 μm, the voltage VN at which the electric field is 450 V is 450 × 4 = 1800 V.

As shown in FIG. 3, the time for the voltage VN to reach 1800 V is 16 seconds. Therefore, the user determines the time point when the user moves backward from 16 seconds by a seconds (16-a seconds) and the time point when the user moves forward by a seconds from 16 seconds (16 + a seconds) as the predetermined time points. In the second embodiment described later, the user determines the time point of 16 seconds as the predetermined time point.

(Modification example)
Next, a modified example of the application of the deterioration diagnosis device 1 will be described with reference to FIG. FIG. 6 is a block diagram showing a configuration of a product inspection device A1 including the capacitance measuring device 10 according to the first embodiment of the present invention. The product inspection device A1 is a device that inspects the vehicle V2 as a product. The product inspection device A1 inspects the performance of the capacitor 2 provided in the power conversion device E2 included in the vehicle V2, for example.

The vehicle V2 is different from the vehicle V1 in that the power conversion device E1 is changed to the power conversion device E2. The power conversion device E2 is different from the power conversion device E1 in that it does not include the deterioration diagnosis device 1. The voltmeter 3, the ammeter 4, and the storage unit 5 may be provided in the power conversion device E2.

As shown in FIG. 6, the product inspection device A1 includes a deterioration diagnosis device 1, a voltmeter 3, an ammeter 4, and a storage unit 5. The capacitor 2 provided in the power conversion device E2 included in the vehicle V2 is connected to the deterioration diagnosis device 1, the voltmeter 3 and the ammeter 4 provided in the product inspection device A1.

When the deterioration diagnosis device 1 is provided in the product inspection device A1, when the product inspection device A1 inspects the vehicle V2, the deterioration diagnosis device 1 performs the deterioration diagnosis of the capacitor 2 provided in the vehicle V2. The deterioration diagnosis device 1 may be provided in a product inspection device that inspects an industrial machine other than the vehicle V2. In this case, the deterioration diagnosis of the capacitor 2 provided in the other industrial machine is performed. Do.

That is, the deterioration diagnosis device 1 may be provided in the product inspection device instead of the vehicle as a product. Therefore, the present invention is not limited in the scope of application to the deterioration diagnosis device provided in the vehicle V1 as a product including the condenser 2, and the deterioration diagnosis provided in the product inspection device A1 for inspecting the vehicle V2 as a product. It also applies to devices.

[Embodiment 2]
Embodiment 2 of the present invention will be described with reference to FIG. For convenience of explanation, the same reference numerals will be added to the members having the same functions as the members described in the first embodiment, and the description will not be repeated. FIG. 7 is a block diagram showing a configuration of a vehicle V3 including the capacitance measuring device 10A according to the second embodiment of the present invention.

As shown in FIG. 7, the vehicle V3 is different from the vehicle V1 in that the capacitance measuring device 10 is changed to the capacitance measuring device 10A. As a result, in the vehicle V3, the deterioration diagnosis device 1 is changed to the deterioration diagnosis device 1A and the power conversion device E1 is changed to the power conversion device E3 as compared with the vehicle V1.

In the capacitance measuring device 10A, the voltage change rate measuring unit 120 is changed to the voltage change rate measuring unit 120A and the calculating unit 130 is changed to the calculating unit 130A as compared with the capacitance measuring device 10. The difference is that the current change rate measuring unit 150 is provided.

The voltage change rate measuring unit 120A further measures the second voltage change rate, which is a differentiated value of the first voltage change rate, in addition to the first voltage change rate measuring unit. The second voltage change rate is, for example, a value obtained by second-order differentiation of the voltage applied to the capacitor 2 at the predetermined time point, and a value obtained by first-order differentiation of the first voltage change rate. At this time, the voltage change rate measuring unit 120A refers to the first voltage change rate stored in the storage unit 5. The voltage change rate measuring unit 120A stores the measured second voltage change rate in the storage unit 5.

The current change rate measuring unit 150 measures the current change rate of the current flowing through the capacitor 2 at the predetermined time point from the current measured value input by the input unit 110. The current change rate is, for example, a value obtained by first-order differentiation of the current flowing through the capacitor 2 at the predetermined time point. At this time, the current change rate measuring unit 150 refers to the current measured value stored in the storage unit 5. The current change rate measuring unit 150 stores the measured current change rate in the storage unit 5.

The calculation unit 130A refers to the voltage measurement value and the current measurement value input by the input unit 110. Further, the calculation unit 130A measures the voltage change rate measuring unit 120A in addition to the voltage measurement value and the current measurement value at the predetermined time point and the first voltage change rate measured by the voltage change rate measurement unit 120A. The admitance of the capacitance and the leakage current of the capacitor 2 is calculated from the second voltage change rate and the current change rate measured by the current change rate measuring unit 150.

At this time, the calculation unit 130A refers to the voltage measurement value, the current measurement value, the first voltage change rate, the second voltage change rate, and the current change rate stored in the storage unit 5. The calculation unit 130A stores the calculated admittance of the capacitance and leakage current of the capacitor 2 in the storage unit 5.

(Details of processing of calculation unit 130A)
In the calculation process of the admittance of the capacitance and the leakage current of the capacitor 2 in the calculation unit 130A, the equivalent circuit shown in FIG. 2 is considered as in the calculation process of the calculation unit 130. Here, consider a case where a certain time point (t seconds) is set as the predetermined time point. In this case, the calculation unit 130A uses the following values in order to calculate the capacitance C and the admittance Y of the capacitor 2.

Specifically, the calculation unit 130A has a voltage measurement value V (t) in t seconds, a current measurement value I (t), a first voltage change rate dV (t) / dt, and a second voltage change rate d ² V. (T) / dt ² and the current change rate dI (t) / dt are used. When the calculation unit 130A uses these values, a simultaneous equation consisting of the following equations (5) and (6) can be obtained from the equivalent circuit shown in FIG.

Further, the following equation (7) can be obtained from the above equations (5) and (6). Then, the following equation (8) can be obtained from the equation (7).

Further, the voltage measurement value, the current measurement value, the first voltage change rate, the second voltage change rate, and the current change rate of the capacitor 2 are obtained by AD (Analog-Digital) conversion of the analog signal in a sampling cycle of Δt seconds. Be done. The calculation of these values is done by digital signal processing. Therefore, the processing of the time derivative of voltage and current is replaced with the following equations (9) and (10) by applying the difference method.

In the above equations (9) and (10), the voltage and current at a time point (t + Δt seconds) advanced by a predetermined minute time (Δt seconds) from a certain time point (t seconds) are defined as Vi and Ii, respectively. Let the voltage and current at the time point (t seconds) be Vj and Ij, respectively. Further, let Vk be the voltage at a time point (t−Δt seconds) that is set back by a predetermined minute time (Δt seconds) from a certain time point (t seconds).

In this way, the calculation unit 130A can calculate the capacitance C and the admittance Y of the capacitor 2 at a certain time point (t seconds). That is, the calculation unit 130A performs the calculation processing of the formulas (5) to (10), and calculates the capacitance C and the admittance Y of the capacitor 2 at a certain time point (t seconds).

According to the above configuration, the admittance Y of the capacitance C of the capacitor 2 and the leakage current I2 is calculated by using the second voltage change rate which is a differentiated value of the first voltage change rate. For example, when the second voltage change rate is obtained by approximation, more information is used than when the first voltage change rate is obtained. Therefore, by calculating the capacitance and admittance Y of the capacitor 2 using the second voltage change rate, the accuracy of calculating the capacitance and admittance Y of the capacitor 2 can be improved.

[Example of realization by software]
The control blocks of the deterioration diagnostic devices 1 and 1A (particularly the input unit 110, the voltage change rate measurement units 120 and 120A, the calculation units 130 and 130A, the result output unit 140 and the current change rate measurement unit 150) are integrated circuits (IC chips). It may be realized by a logic circuit (hardware) formed in the above, or it may be realized by software.

In the latter case, the deterioration diagnostic devices 1 and 1A include a computer that executes a program instruction, which is software that realizes each function. The computer includes, for example, one or more processors and a computer-readable recording medium that stores the program. Then, in the computer, the object of the present invention is achieved by the processor reading the program from the recording medium and executing the program. As the processor, for example, a CPU (Central Processing Unit) can be used. As the recording medium, a "non-temporary tangible medium", for example, a ROM (Read Only Memory) or the like, a tape, a disk, a card, a semiconductor memory, a programmable logic circuit, or the like can be used. Further, a RAM (Random Access Memory) or the like for expanding the program may be further provided. Further, the program may be supplied to the computer via an arbitrary transmission medium (communication network, broadcast wave, etc.) capable of transmitting the program. It should be noted that one aspect of the present invention can also be realized in the form of a data signal embedded in a carrier wave, in which the program is embodied by electronic transmission.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the embodiments obtained by appropriately combining the technical means disclosed in the different embodiments. Is also included in the technical scope of the present invention.

1, 1A Deterioration diagnosis device 2 Capacitor 10, 10A Capacitance measurement device 110 Input unit 120, 120A Voltage change rate measurement unit 130, 130A Calculation unit 140 Result output unit 150 Current change rate measurement unit

Claims (9)

An input unit for inputting a voltage measurement value of a voltage applied to a capacitor and a current measurement value of a current flowing through the capacitor.
A voltage change rate measuring unit that measures the first voltage change rate of the voltage applied to the capacitor at a predetermined time point from the voltage measured value input by the input unit.
With reference to the voltage measurement value and the current measurement value input by the input unit, at least the voltage measurement value and the current measurement value at the predetermined time point, and the voltage change rate measurement unit measured the first. 1 A capacitance measuring device including a voltage change rate and a calculation unit for calculating the capacitance of the capacitor from. The voltage change rate measuring unit measures the first voltage change rate at two time points as the predetermined time points.
The calculation unit is composed of the voltage measurement value and the current measurement value at the two time points, the first voltage change rate at the two time points measured by the voltage change rate measurement unit, and the capacitor. The capacitance measuring device according to claim 1, wherein the capacitance is calculated. The capacitance measuring device according to claim 2, wherein the period between the two time points is not more than a predetermined period. A current change rate measuring unit for measuring the current change rate of the current flowing through the capacitor at a predetermined time point from the current measured value input by the input unit is further provided.
The voltage change rate measuring unit further measures the second voltage change rate, which is a value obtained by differentiating the first voltage change rate.
The calculation unit
In addition to the voltage measurement value and the current measurement value at the predetermined time point, and the first voltage change rate measured by the voltage change rate measuring unit,
A claim characterized in that the capacitance of the capacitor is calculated from the second voltage change rate measured by the voltage change rate measuring unit and the current change rate measured by the current change rate measuring unit. Item 1. The capacitance measuring device according to Item 1. An input unit for inputting a voltage measurement value of a voltage applied to a capacitor and a current measurement value of a current flowing through the capacitor.
A voltage change rate measuring unit that measures the voltage change rate of the voltage applied to the capacitor at a predetermined time point from the voltage measured value input by the input unit.
With reference to the voltage measurement value and the current measurement value input by the input unit, at least the voltage measurement value and the current measurement value at the predetermined time point, and the voltage measured by the voltage change rate measurement unit. A calculation unit that calculates the admittance of the capacitance and leakage current of the capacitor from the rate of change,
From the amount of decrease in the capacitance of the capacitor calculated by the calculation unit from the initial value and the amount of increase in the leakage current of the capacitor calculated by the calculation unit from the initial value in the admittance of the capacitor. A deterioration diagnosis device including a result output unit that outputs the result of deterioration diagnosis. The deterioration diagnostic apparatus according to claim 5, wherein the result output unit further outputs the result of life prediction of the capacitor from the decrease amount and the increase amount. A voltage measurement process that measures the voltage applied to the capacitor as a voltage measurement value,
A current measurement process that measures the current flowing through the capacitor as a current measurement value, and
A voltage change rate measuring step of measuring the voltage change rate of the voltage applied to the capacitor at a predetermined time point from the voltage measured value measured in the voltage measuring step.
With reference to the voltage measurement value and the current measurement value measured in each of the voltage measurement step and the current measurement step, at least the voltage measurement value and the current measurement value at the predetermined time point, and the voltage change. A capacitance measuring method comprising: a voltage change rate measured in a rate measuring step and a calculation step of calculating the capacitance of the capacitor from the voltage change rate. A voltage measurement process that measures the voltage applied to the capacitor as a voltage measurement value,
A current measurement process that measures the current flowing through the capacitor as a current measurement value, and
A voltage change rate measuring step of measuring the voltage change rate of the voltage applied to the capacitor at a predetermined time point from the voltage measured value measured in the voltage measuring step.
With reference to the voltage measurement value and the current measurement value measured in each of the voltage measurement step and the current measurement step, at least the voltage measurement value and the current measurement value at the predetermined time point, and the voltage change. A calculation step for calculating the admittance of the capacitance and leakage current of the capacitor from the voltage change rate measured in the rate measurement step, and
From the amount of decrease in the capacitance of the capacitor calculated in the calculation step from the initial value and the amount of increase in the leakage current of the capacitor calculated in the calculation step from the initial value in the admittance. A deterioration diagnosis method including a result output process for outputting the result of deterioration diagnosis of a capacitor. The capacitance measurement program for operating a computer as the capacitance measuring device according to claim 1, wherein the capacitance for operating the computer as the input unit, the voltage change rate measuring unit, and the calculating unit. Capacitance measurement program.

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