JP4456584B2 - Method and system for measuring DC internal resistance value of electric double layer capacitor - Google Patents

Description

  The present invention relates to a method and a system for measuring a DC internal resistance value of an electric double layer capacitor.

  Storage batteries and electric double layer capacitors have been put to practical use as power storage devices. In these storage batteries and electric double layer capacitors, high and low internal resistance values are considered as one guideline for performance. Therefore, it is preferable that the internal resistance value of the power storage device can be measured with high accuracy, but since the power storage device stores and discharges charges, the resistance value cannot be easily measured like a fixed resistor.

  Conventionally, an AC four-terminal method using a frequency of 1 [kHz] is known as a method for measuring an AC internal resistance value of a storage battery having a DC electromotive voltage. In connection with this AC four-terminal method, a method for short-time charging of a capacitor of a high-pass filter (filter with a capacitor and a resistor) that removes the DC component of the inter-terminal voltage of the storage battery is disclosed in JP-A-11-118891. Is disclosed.

  On the other hand, regarding the test method of the electric double layer capacitor, the measurement method of the AC internal resistance value and the DC internal resistance value is the standard “EIAJ RC-2377” of the Japan Electronic Machinery Manufacturers Association standard. Method "and" 3.4.2 DC resistance method ".

  FIG. 5 shows an AC resistance measurement circuit 2 defined in the EIAJ standard. This AC resistance method measurement circuit 2 has an AC ammeter with an oscillator 4 having a frequency of 1 [kHz] and an AC current output of 1 [mA] to 10 [mA] with respect to an electric double layer capacitor Cx as a test capacitor. 6 and an AC voltmeter 8 is connected between terminals of the electric double layer capacitor Cx.

In this case, when the AC voltage measured by the AC voltmeter 8 is U [Vrms] and the AC current measured by the AC ammeter 6 is I [Arms], the AC internal resistance value Ra [Ω of the electric double layer capacitor Cx ] Is calculated by the following equation (1).
Ra = U ÷ I (1)

  FIG. 6 shows a DC resistance measurement circuit 12 defined in the EIAJ standard. In the DC resistance method measurement circuit 12, a common contact 15a of the changeover switch 15 is connected to one end side of the electric double layer capacitor Cx, and a constant current is provided between one fixed contact 15b and the other end side of the electric double layer capacitor Cx. A constant voltage power supply 16 is connected, a series circuit of a DC ammeter 18 and a constant current discharger 20 is connected between the other fixed contact 15c and the other end of the electric double layer capacitor Cx, and further the electric double layer capacitor Cx The DC voltmeter 22 is connected between these terminals.

  In such a configuration, the changeover switch 15 is set to the constant current / constant voltage power supply 16 side, the electric double layer capacitor Cx is charged to a predetermined voltage (rated voltage) E, and then the predetermined voltage E is applied for 30 minutes to continue charging.

  After charging for 30 minutes, the changeover switch 15 is set to the constant current discharger 20 side, and the electric double layer capacitor Cx is discharged at a constant current by the constant current discharger 20, and the terminal voltage of the electric double layer capacitor Cx at this time Is measured by a DC voltmeter 22 and recorded.

  FIG. 7 shows an enlarged view of the vicinity of the predetermined voltage E of the voltage characteristic 24 between the terminals of the electric double layer capacitor Cx measured by the DC voltmeter 22. Actually, the direct-current voltmeter 22 measures from a voltage 0 [V] (not shown) to a predetermined voltage E [V].

In this case, an auxiliary line 27 is drawn by extending the time-varying linear portion of the inter-terminal voltage characteristic 24, and a voltage drop ΔV2 [V] obtained from the intersection A of the auxiliary line 27 and the time axis 28 at the start of discharge. Read. Here, when the discharge current read by the DC ammeter 18 is I [A], the DC internal resistance value Rd [Ω] of the electric double layer capacitor Cx is calculated by the following equation (2). The voltage drop ΔV1 is a voltage that instantaneously drops at the start of discharge.
Rd = ΔV2 ÷ I (2)

JP-A-11-118891 Electric double layer capacitor test method, EIAJ RC-2377, P1-P6, established in April 2000, published by Japan Electronic Machinery Association

  As described above, in EIAJ RC-2377, an AC resistance method and a DC resistance method are defined as methods for measuring the internal resistance value of an electric double layer capacitor. In general, the AC resistance method is characterized in that the time required for measurement is short and the internal resistance value can be measured relatively easily and accurately.

  By the way, although the alternating current value passed through the electric double layer capacitor by the AC resistance method is 1 to 10 [mA], in the case of the electric double layer capacitor for high output use, it is actually a condition of several amperes to several tens of amperes. In many cases, measurement conditions and use conditions are greatly different.

  Furthermore, the internal resistance value is measured from the amount of change in voltage and current in a short time of 1 [kHz] in the AC resistance method and about 1 millisecond in time conversion. Actually, the measurement conditions and the use conditions are greatly different from each other because they are often used in a long charge / discharge cycle of several seconds.

  Actually, even if an electric double layer capacitor for high power use is measured by the above-described AC resistance method and DC resistance method and the measurement results are compared, they do not agree.

  Reflecting the ability of electric double layer capacitors for high output applications is the DC internal resistance value measured by the DC resistance method close to actual use conditions, and measuring the internal resistance value of electric double layer capacitors for high output applications We found that the AC resistance method was not appropriate. That is, the DC resistance method is appropriate as a method for measuring the internal resistance value of the electric double layer capacitor.

  However, in the DC resistance method defined in EIAJ-2377, as described with reference to FIGS. 6 and 7, the voltage between the terminals of the electric double layer capacitor Cx is measured, but the electric double layer capacitor Cx is Since the internal resistance value is very small, the voltage drop ΔV2 is extremely small with respect to the predetermined voltage (rated voltage) E. As a result, there is a problem that the measurement is performed in a narrow range during the full scale of the DC voltmeter 22 and cannot be accurately measured. For example, it is more accurate to measure a change of 1 volt at 2 [V] full scale than to measure a change of 1 volt at 100 [V] full scale.

  Further, a high-pass filter disclosed in Japanese Patent Application Laid-Open No. 11-118891 that blocks the DC component of the voltage between the terminals of the storage battery in connection with the AC four-terminal method is a capacitor / resistor filter (a capacitor is connected to the storage battery). The filter is connected between the AC voltmeter and a resistor is connected between the input side of the AC voltmeter and the ground, and the cutoff frequency is close to 1 [kHz]. The problem that voltage fluctuation over a long time of about 10 seconds from the start of discharge necessary for measurement of the DC internal resistance value of the multilayer capacitor cannot be measured with high accuracy is not solved.

  The present invention has been made in view of such problems, and a method for measuring the DC internal resistance value of an electric double layer capacitor, which can measure the DC resistance value of the electric double layer capacitor with high accuracy, and its The purpose is to provide a system.

  The method for measuring a direct current internal resistance value of an electric double layer capacitor according to the present invention includes the following features (1) to (3).

  (1) After charging the electric double layer capacitor and the DC blocking capacitor, each of which is electrically connected to one end, to a predetermined voltage, opening the other end of the DC blocking capacitor; A constant current discharger is connected to the one end, and when the electric double layer capacitor is discharged at a constant current, the time change of the voltage due to the discharge of the electric double layer capacitor appearing at the open end of the DC blocking capacitor is measured by a DC voltmeter. A step of measuring, and extending a linear portion of a time change in voltage due to the discharge of the electric double layer capacitor measured by the DC voltmeter, drawing an auxiliary line, and a time at the start of discharging the auxiliary line and the electric double layer capacitor Read the voltage drop calculated from the intersection with the shaft, and calculate the DC internal resistance value of the electric double layer capacitor as follows: “DC internal resistance value = drop Characterized by a step of determining a pressure ÷ constant current discharge value. "

  According to the invention having the feature (1), of the electric double layer capacitor and the DC blocking capacitor charged to a predetermined voltage, the other end of the DC blocking capacitor is opened, and the electric double layer capacitor is discharged at a constant current. The time variation of the voltage due to the discharge of the electric double layer capacitor that appears at the open end of the DC blocking capacitor is measured with a DC voltmeter, so the high voltage determined by the input resistance of the DC blocking capacitor and the DC voltmeter The cut-off frequency is extremely low, and long-time voltage changes can be accurately measured in a range close to the full scale of the DC voltmeter.

  (2) In this case, a film capacitor with a small leakage current is preferable as the DC blocking capacitor.

  According to the invention having the feature (2), the DC resistance value can be measured with higher accuracy.

  (3) In the above feature (1) or (2), in the step of measuring the time change of the voltage due to the discharge of the electric double layer capacitor appearing at the open end of the DC blocking capacitor with the DC voltmeter, A voltage follower is inserted between a capacitor and the DC voltmeter, and a voltage appearing at an output terminal of the voltage follower is measured by the DC voltmeter.

  According to the invention having the feature (3), since the input resistance value of the DC voltmeter can be further increased, the DC resistance value can be measured with higher accuracy. In addition, the value of the DC blocking capacitor can be reduced.

  The measurement system for the DC internal resistance value of the electric double layer capacitor according to the present invention has the following features (4) to (7).

(4) A system for measuring the DC internal resistance value of an electric double layer capacitor, the constant current constant voltage power source for charging the electric double layer capacitor to a predetermined voltage, and the electric double layer capacitor charged to a predetermined voltage. A constant current discharger that discharges by current, a first fixed contact is connected to the constant current constant voltage power source, a second fixed contact is connected to the constant current discharger, and a common contact is connected to the electric double layer capacitor A first switch to be connected; a DC blocking capacitor having one end electrically connected to a connection point of the electric double layer capacitor and the first switch; and one end connected to the other end of the DC blocking capacitor; A series circuit of a second switch and a resistor, the other end of which is connected to a reference voltage;
A DC voltmeter connected to the other end of the DC blocking capacitor; and a control means, wherein the control means closes the second switch, and sets the first switch to the constant current constant voltage power source side. The electric double layer capacitor is charged to the predetermined voltage, and after the DC blocking capacitor is charged from the reference voltage to the predetermined voltage, the second switch is opened to connect the other end of the DC blocking capacitor. When the electric double layer capacitor is discharged at a constant current by switching the first switch to the constant current discharger side, the voltage due to the discharge of the electric double layer capacitor appearing at the open end of the DC blocking capacitor is opened. The time change was measured with a DC voltmeter, and the voltage change with time due to the discharge of the electric double layer capacitor was measured with the DC voltmeter. The auxiliary line is extended, the voltage drop obtained from the intersection of the auxiliary line and the time axis at the start of discharge of the electric double layer capacitor is read, and the DC internal resistance value of the electric double layer capacitor is expressed as `` DC internal resistance value = voltage drop / constant current discharge value ”.

  According to the invention having the feature (4), of the electric double layer capacitor and the DC blocking capacitor charged to a predetermined voltage, the other end of the DC blocking capacitor is opened, and the electric double layer capacitor is discharged at a constant current. The time variation of the voltage due to the discharge of the electric double layer capacitor that appears at the open end of the DC blocking capacitor is measured with a DC voltmeter, so the high frequency cutoff frequency due to the input resistance of the DC blocking capacitor and DC voltmeter Is extremely low, and long-term voltage changes can be accurately measured in a range close to the full scale of a DC voltmeter.

  (5) In the above feature (4), the DC blocking capacitor and the DC ammeter are further inserted, an input terminal is connected to the other end of the DC blocking capacitor, and an output terminal is connected to the DC blocking capacitor. By providing the voltage follower connected to the DC voltmeter, the input resistance value of the DC voltmeter can be further increased, so that the DC resistance value can be measured with higher accuracy. In addition, the value of the DC blocking capacitor can be reduced.

  (6) In the above feature (4) or (5), the electric double layer capacitor is further inserted between the electric double layer capacitor and one end of the DC blocking capacitor, and input terminals are respectively connected between the terminals of the electric double layer capacitor. Is connected, and the output terminal is provided with a differential amplifier connected to one end of the DC blocking capacitor, so that the in-phase component appearing between the terminals of the electric double layer capacitor can be removed, so that the DC resistance value can be measured more accurately. be able to.

  (7) In the above feature (5) or (6), the DC blocking capacitor is a film capacitor, the second switch is a junction FET, and the voltage follower is a junction FET input. The DC resistance value of the multilayer capacitor can be measured with higher accuracy.

  According to the present invention, the DC resistance value of the electric double layer capacitor can be measured with high accuracy.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings to be referred to below, components corresponding to those shown in FIG. 6 are given the same reference numerals and detailed description thereof is omitted. Moreover, in order to avoid complexity, it demonstrates with reference to the said FIG. 6, FIG. 7 as needed.

  FIG. 1 shows the configuration of a DC internal resistance measurement system 32 for an electric double layer capacitor according to this embodiment.

  This measurement system 32 is a system obtained by improving the DC resistance method described with reference to FIGS. 6 and 7 so that the DC resistance value of the electric double layer capacitor Cx can be measured more accurately and easily.

  This measurement system 32 basically includes a DC resistance method measurement circuit 12a, a DC voltmeter 22, and a DC resistance method measurement circuit 12a, each having a configuration in which the DC voltmeter 22 is substantially separated from the DC resistance method measurement circuit 12 shown in FIG. And an interface circuit 25 disposed between the DC voltmeter 22 and a DC resistance method measuring circuit 12a, the DC voltmeter 22, and a control device 26 for controlling the operation of the interface circuit 25. The control device 26 includes a microcomputer. The microcomputer includes a ROM (read only memory) in which a program and the like are stored, and a CPU having a control, calculation, and determination function by executing the program stored in the ROM. (Central processing unit), RAM (random access memory), input / output interfaces such as an A / D converter and a D / A converter, a clock, a counter, a timer, and the like.

  The DC resistance method measurement circuit 12a includes a constant current constant voltage power supply 16 that charges the electric double layer capacitor Cx to a predetermined voltage (for example, a rated voltage) E, and a constant current value of the electric double layer capacitor Cx that is charged to the predetermined voltage E. A constant current discharger 20 that discharges at I, a DC ammeter 18 that measures a constant current value I, a first fixed contact 14b connected to a constant current constant voltage power supply 16, and a second fixed contact 14c connected to a DC ammeter. 18 and a constant current discharger 20 connected to a series circuit, a third fixed contact 14d is grounded through a discharge resistor 48, and a common contact 14a is composed of a first switch 14 connected to an electric double layer capacitor Cx. Yes. The first switch 14 is in a default state in which the common contact 14a and the third fixed contact 14d are connected when no signal is supplied to the switching control terminal 14e. The first switch 14 includes a mechanical switch or a multiplexer with an electronic switch using a power transistor (MOSFET).

  The interface circuit 25 includes a differential amplifier 29 having a gain of 1 to amplify the voltage across the electric double layer capacitor Cx, a voltage follower 30 connected to the input side of the DC voltmeter 22, and an output side of the differential amplifier 29. And a DC blocking capacitor 34 inserted between the input side of the voltage follower 30 and a DC blocking capacitor charging path switch circuit 42 connected between the input side of the voltage follower 30 and the ground. The

  The DC blocking capacitor charging path switch circuit 42 includes a second switch 36, a resistor 38 that limits a charging current, and a reference voltage generator 40 that generates a reference voltage Er. The second switch 36 is a switch using a junction FET, and has a drain terminal connected to the coupling point 50, a source terminal connected to the resistor 38, and a gate terminal connected to the control device 26.

  In this embodiment, a constant current constant voltage power supply 16, a DC ammeter 18, a constant current discharger 20, a differential amplifier 29, a voltage follower 30, a DC voltmeter 22, a reference voltage generator 40, Since the control device 26 is an active circuit, a predetermined DC voltage is applied, but it is not drawn because it becomes complicated.

  The control device 26 can adjust the constant current value and the constant voltage value E of the constant current and constant voltage power supply 16, the discharge constant current value I of the constant current discharger 20, and the reference voltage Er of the reference voltage generator 40, respectively. It is. Further, the control device 26 can measure the time change characteristic of the voltage between the terminals of the electric double layer capacitor Cx represented by the current value I of the DC ammeter 18 and the voltage characteristic of the output of the DC voltmeter 22. Furthermore, the control device 26 can switch the first switch 14 and the second switch 36, respectively.

  As the operational amplifier for the voltage follower 30, a junction type FET input type low power consumption operational amplifier made by New Japan Radio Co., Ltd., model “NJM062” was used.

  As the FET for the second switch 36, a junction type FET manufactured by Toshiba Corporation, model “2SK209” was used.

  As the differential amplifier 29, a differential amplifier manufactured by Linear Technology Corporation, model “LT1990A” was used. Since LT1990A does not support 0 [V] output, it is actually necessary to apply a predetermined voltage to a REF terminal (not shown). For example, when the positive terminal of the reference voltage generator 40 is connected to the REF terminal of the differential amplifier 29, the reference voltage Er can be obtained at the output (coupling point 52). However, the differential amplifier has an output of 0 [V]. In consideration of the fact that compatible ones can be used and the simplicity of the circuit, the output is 0 [V] in the example of FIG.

  As the DC blocking capacitor 34, a non-inductive capacitor using a polypropylene film manufactured by Matsushita Electric Industrial Co., Ltd., model “ECQ-P1H104JZ” was used in parallel with 0.3 [μF].

  Next, the operation of the above-described embodiment will be described in detail based on the flowchart relating to the application program shown in FIG. Unless otherwise specified, the control subject is the control device 26, but it is complicated to refer to it every time, so that reference is made as necessary.

  First, in step S1, initialization is performed in a state where the first switch 14 is connected to the discharge resistor 48 and the second switch 36 is in an on state (closed state). In this state, the electric charge of the electric double layer capacitor Cx is completely discharged through the discharge resistor 48 and the inter-terminal voltage is set to 0 [V]. In the DC blocking capacitor 34, the end on the coupling point 50 side is set to the reference voltage Er, and the coupling point 52 side is set to 0 [V].

  In this initial setting, the constant current constant voltage power supply 16 is set to a predetermined voltage E that is a rated voltage of the electric double layer capacitor Cx. The discharge current I generated by the constant current discharger 20 may depend on the EIAJ standard, but in this embodiment, the discharge current value (for example, the upper limit value, the lower limit value, and the median value) I under actual use conditions is set. . The full scale of the DC ammeter 18 is set to a range (full scale) that is larger than the set discharge current value I and closest to the discharge current value I. However, in this embodiment, the direct current ammeter 18 is for monitoring / confirmation and need not be provided.

  Further, the reference voltage Er of the reference voltage generator 40 is adjusted in order to increase accuracy using a range close to the entire range within a predetermined full scale of the DC voltmeter 22. For example, as shown in FIG. 3, when the voltage change in the range of the voltage E1 to the predetermined voltage E is to be measured by the DC voltmeter 22, the reference voltage Er is set to (E−E1) = + ΔE [V]. Good. That is, when the electric double layer capacitor Cx is discharged later, the voltage at the coupling point 50 between the DC blocking capacitor 34 and the voltage follower 30 becomes negative (−E from the voltage E to the voltage E1 within the time required for measurement). Since −E1) = − ΔE [V] decreases, by setting the voltage at the coupling point 50 to + ΔE [V], the DC voltmeter 22 measures the change voltage from + ΔE [V] to 0 [V]. It will be good. In this case, the predetermined full scale of the DC voltmeter 22 is set to a range larger than + ΔE [V] and closest to + ΔE [V].

  Next, in step S2, the first switch 14 is connected to the constant current constant voltage power supply 16 at time t1. Then, as shown from time t1 to time t2 in FIG. 3, the terminal voltage of the electric double layer capacitor Cx is linearly charged from 0 [V] to a predetermined voltage E [V]. At this time, the terminal on the coupling point 52 side of the DC blocking capacitor 34 is also charged to a predetermined voltage E [V] (Note that, as described above, when the output of the differential amplifier 29 is Er [V]. , E + Er [V]).

  Next, in step S3, the charge continuation state in which the predetermined voltage E is applied to the electric double layer capacitor Cx is maintained for 30 minutes from time t2 to time t10.

  Next, in step S4, the second switch 36 is opened immediately before time t10, and the first switch 14 is connected to the constant current discharger 20 side at time t10. As a result, the electric double layer capacitor Cx starts discharging at a constant current I from time t10.

  In step S5, from the time point t10, until the voltage Er = + ΔE becomes the voltage 0 [V], the time point t11 every 5 seconds from the time point t10 (5 seconds after the time point t10), t12 (time point t10 to 10 After a second), the voltage is measured at t13 (15 seconds after time t10) (actually, the voltage of the DC voltmeter 22 is taken every 10 [ms]).

  In this way, when the measured voltage of the DC voltmeter 22 becomes 0 [V] (time t14), the measurement end setting is performed in step S6.

  That is, after the second switch 36 is turned on (closed), the first switch 14 is connected to the discharge resistor 48 side to prepare for the next measurement. The first switch 14 may remain connected to the constant current discharger 20 side.

  Next, in step S7, the linear portion of the measured time-varying voltage characteristic 24 shown in FIG. 3 is extended to connect, for example, a voltage value at time t11 5 seconds after time t10 and time t12 after 10 seconds. Then, the auxiliary line 27 is drawn, the voltage drop ΔV2 [V] obtained from the intersection A of the auxiliary line 27 and the time axis 28 at the start of discharge is read, and the discharge current read by the DC ammeter 18 is I When [A], the DC internal resistance value Rd [Ω] of the electric double layer capacitor Cx is calculated by the above-described equation (2). The voltage drop ΔV1 is a voltage that instantaneously drops at the start of discharge.

  As described above, according to the embodiment described above, of the electric double layer capacitor Cx and the DC blocking capacitor 34 charged to the predetermined voltage E [V], the other end of the DC blocking capacitor 34 is opened to When the multilayer capacitor Cx is discharged at a constant current value I, the time change of the voltage due to the discharge of the electric double layer capacitor Cx appearing at the open end of the DC blocking capacitor 34 is measured by the controller 26 through the DC voltmeter 22. Therefore, the high cut-off frequency due to the input resistance of the DC blocking capacitor 34 and the DC voltmeter 22 becomes a very low value due to the insertion of the voltage follower 30 of the junction type FET input, and for a long time, for example, 1 second to several seconds The above voltage change can be accurately measured in a range close to the full scale of the DC voltmeter 22.

  Further, since the differential amplifier 29 is inserted between the electric double layer capacitor Cx and one end of the DC blocking capacitor 34, the in-phase component appearing between the terminals of the electric double layer capacitor Cx can be removed, so that the accuracy is improved. DC resistance value can be measured.

  Thus, according to this embodiment, the DC resistance value of the electric double layer capacitor Cx can be measured with high accuracy.

  Note that the DC internal resistance value measurement system 32 of the electric double layer capacitor in FIG. 1 can be changed to a measurement system 32A shown in FIG. 4 within a range that satisfies the accuracy. That is, any one of the differential amplifier 29, the voltage follower 30, and the reference voltage generator 40 can be removed from the measurement system 32 of FIG. 1 according to the specification accuracy. In the case of the measurement system 32A in the example of FIG. 4, the measurement range of the DC voltmeter 22 is a range from 0 [V] to −ΔV [V].

  Note that the present invention is not limited to the above-described embodiment, and it is needless to say that various configurations can be adopted based on the contents described in this specification.

1 is a configuration diagram of a measurement system for a DC internal resistance value of an electric double layer capacitor according to an embodiment of the present invention. FIG. It is a flowchart with which it uses for operation | movement description of the example of FIG. It is a time change characteristic view of the voltage between terminals at the time of charge and discharge of an electric double layer capacitor. It is a block diagram of the measurement system of the direct current | flow internal resistance value of the electric double layer capacitor which concerns on other embodiment of this invention. It is a measurement circuit diagram of the alternating current resistance method of an electric double layer capacitor. It is a measurement circuit diagram of the direct current resistance method of an electric double layer capacitor. It is a time change characteristic view of the voltage between terminals at the time of charge and discharge of an electric double layer capacitor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 14 ... 1st switch 16 ... Constant current constant voltage power supply 22 ... DC voltmeter 26 ... Control apparatus 29 ... Differential amplifier 30 ... Voltage follower 34 ... Capacitor for DC blocking 36 ... 2nd switch Cx ... Electric double layer capacitor

Claims (2)

A measurement system for a DC internal resistance value of an electric double layer capacitor,
A constant current constant voltage power source for charging the electric double layer capacitor to a predetermined voltage;
A constant current discharger for discharging the electric double layer capacitor charged to a predetermined voltage with a constant current;
A first switch having a first fixed contact connected to the constant current constant voltage power source, a second fixed contact connected to the constant current discharger, and a common contact connected to the electric double layer capacitor;
Differential amplifiers each having an input terminal connected between terminals of the electric double layer capacitor;
A DC blocking capacitor having one end connected to the output end of the differential amplifier ;
A series circuit of a second switch and a resistor, one end of which is connected to the other end of the DC blocking capacitor and the other end of which is connected to a reference voltage generator for generating a reference voltage ;
A voltage follower having an input end connected to the other end of the DC blocking capacitor ;
A DC voltmeter connected to the output end of the voltage follower ;
Control means,
The control means includes
The second switch is closed, the first switch is set to the constant current constant voltage power source side, the electric double layer capacitor is charged to the predetermined voltage, and the DC blocking capacitor is changed from the reference voltage to the predetermined voltage. The second switch is opened, the other end of the DC blocking capacitor is opened, the first switch is switched to the constant current discharger side, and the electric double layer capacitor is discharged with constant current. The time change of the voltage due to the discharge of the electric double layer capacitor appearing at the open end of the DC blocking capacitor is measured with a DC voltmeter, and the time change of the voltage due to the discharge of the electric double layer capacitor measured with the DC voltmeter An auxiliary line is drawn by extending the straight line, and the intersection of the auxiliary line and the time axis at the start of discharge of the electric double layer capacitor And the DC internal resistance value of the electric double layer capacitor is calculated as “DC internal resistance value = drop voltage ÷ constant current discharge value”. Value measuring system. In the measurement system of the direct current internal resistance value of the electric double layer capacitor according to claim 1 ,
The system for measuring a DC internal resistance value of an electric double layer capacitor, wherein the DC blocking capacitor is a film capacitor, the second switch is a junction FET, and the voltage follower is a junction FET input.

Images