Short circuit detection device and short circuit detection method

Abstract

To detect a short circuit generated in a detection target object without rapidly sampling a measurement signal of the detection target object.SOLUTION: A short-circuit detector 100 for detecting a short circuit generated in a detection target object 1 charges the detection target object 1 until the voltage of the detection target object 1 reaches a predetermined voltage value V1, with a current I controlled to be constant, and measures a signal generated in the detection target object 1. The short-circuit detector 100 includes: a maximum value holding circuit 140A for holding the peak of a measurement signal Vmi and outputting a first holding signal Vh1 showing the peak of the held measurement signal Vmi; and a change holding circuit 140B for holding the peak of a differential signal showing the difference between the measurement signal Vmi and the first holding signal Vh1 and outputting a second holding signal Vh2 showing the peak of the held differential signal. The short-circuit detector 100 further has a processing unit 200 for determining whether there is a change in the measurement signal Vmi on the basis of the second holding signal Vh1 output from the change holding circuit 140B.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a short circuit detection device and a short circuit detection method. [Background technology]

[0002] Patent Document 1 discloses an inspection device that determines whether the object to be detected is a defective secondary battery in which foreign matter has been mixed in the positive electrode composite by charging the secondary battery to a predetermined voltage that is equal to or greater than the withstand voltage and measuring the voltage drop of the secondary battery after leaving it for a predetermined period of time. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-251538 Summary of the Invention [Problem to be solved by the invention]

[0004] The above-described inspection device is configured to measure the voltage drop of the charged object to be detected when the object is left for a predetermined period of time, and therefore it is necessary to leave the object for a predetermined period of time, which takes time to detect self-discharge (insulation failure) due to an internal short circuit caused by a foreign object contained in the object to be detected.

[0005] To accurately detect short-term short circuits, such as internal short circuits caused by foreign matter contamination, momentary insulation failure, and insulation deterioration, high-speed sampling is required. However, achieving this requires an expensive device configuration. Furthermore, since such short-term short circuits depend on the individual state of the object to be detected, there is a problem in that it is unknown when they will occur.

[0006] The present invention has been made in light of these problems, and has as its object to detect a short-term short circuit that occurs in an object to be detected without high-speed sampling of the measurement signal of the object to be detected. [Means for solving the problem]

[0007] According to one aspect of the present invention, a short-circuit detection device for detecting a short circuit occurring in a detection object includes a supplying means for charging the detection object with a constant current controlled current until the voltage of the detection object reaches a predetermined voltage value, and a measuring means for measuring a signal generated in the detection object by the supplying means. The short-circuit detection device further includes a first holding circuit for holding a peak of a measurement signal generated by the measuring means and outputting a first holding signal indicative of the held peak of the measurement signal, and a second holding circuit for holding a peak of a differential signal indicative of the difference between the measurement signal and the first holding signal and outputting a second holding signal indicative of the held peak of the differential signal. The short-circuit detection device also includes a determining means for determining whether or not the measurement signal fluctuates based on the second holding signal output from the second holding circuit. [Effects of the Invention]

[0008] According to this aspect, a hold signal having a magnitude of the difference between the hold signal at the peak of the measurement signal and the measurement signal can be obtained, so that both a temporary rise and a temporary fall of the measurement signal caused by a short-term short circuit can be detected. Therefore, since fluctuations can be obtained even by slow sampling of the measurement signal, a short-term short circuit occurring in the object to be detected can be detected without high-speed sampling of the measurement signal of the object to be detected. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram showing the functional configuration of a short circuit detection device according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a circuit diagram showing an example of the configuration of a current measuring unit and a fluctuation detecting circuit in the short circuit detecting device. [Figure 3] FIG. 3 is a circuit diagram showing an example of the configuration of a peak hold circuit in the fluctuation detection circuit. [Figure 4] FIG. 4 is a diagram for explaining the operation of the fluctuation detection circuit. [Figure 5] FIG. 5 is a diagram showing an example of detecting fluctuations in the measurement signal during the charging period. [Figure 6] FIG. 6 is a diagram showing an example of changing the time rate of change of the voltage generated in the detection object during the charging period. [Figure 7] FIG. 7 is a flowchart showing an example of a processing procedure of the short circuit detection method according to the first embodiment. [Figure 8] FIG. 8 is a flowchart showing the short circuit detection process in the short circuit detection method. [Figure 9] FIG. 9 is a block diagram showing the functional configuration of a short circuit detection device according to the second embodiment of the present invention. [Figure 10] FIG. 10 is a diagram showing an example of detecting fluctuations in the measurement signal during the charging period. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0011] (First embodiment) FIG. 1 is a block diagram showing the functional configuration of a short circuit detection device 100 according to the first embodiment.

[0012] The short circuit detection device 100 is a device for detecting a short circuit that occurs in the detection object 1. The short circuit here includes not only a steady short circuit, but also a short-term short circuit such as a momentary insulation failure or insulation deterioration caused by an abnormality that occurs in the detection object 1.

[0013] Causes of short-term short circuits include, for example, the inclusion of metallic foreign matter in the electrodes that make up the battery, the occurrence of contamination, burrs between the battery electrodes and the battery exterior, cracks that occur in multilayer ceramic capacitors, and abnormalities such as micro-short circuits between board patterns.

[0014] In this way, the short circuit detection device 100 detects a short circuit caused by the above-mentioned abnormality occurring in the detection object 1. The short circuit detection device 100 is used, for example, to measure or test the detection object 1 by supplying (applying) a DC electrical signal to the detection object 1.

[0015] The short circuit detection device 100 in the first embodiment supplies a DC voltage to the object 1 to measure the insulation resistance R of the object 1 to be detected based on the magnitude of the leakage current output from the negative electrode (-) of the object 1 to be detected.

[0016] The object to be detected 1 is an object having at least a capacitance C, and when a DC electrical signal is supplied to the object, an abnormality occurs in the object, causing a temporary fluctuation in the voltage signal generated in the object or the current signal flowing through the object.

[0017] Hereinafter, the rise and fall of the electrical signal from a standard level will be referred to as a "temporary rise," and the fall and rise of the electrical signal from a standard level will be referred to as a "temporary fall." These temporary fluctuations will also be simply referred to as "fluctuations."

[0018] An example of the detection object 1 is a secondary battery. A secondary battery is a storage battery configured to be chargeable and dischargeable, and is an electricity storage device including a capacitor-type electricity storage element such as an electric double layer capacitor. The secondary battery may be a battery pack in which multiple cells are connected in parallel, series, or series-parallel, or may be a single cell.

[0019] Examples of secondary batteries include lead acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries, metal lithium batteries, lithium ion batteries, lithium ion polymer batteries, all-solid-state lithium ion batteries, sodium ion batteries, etc. In addition, aqueous solution-based electric double layer capacitors, wastewater solution-based electric double layer capacitors, etc. can also be used as secondary batteries.

[0020] The detection object 1 in the first embodiment is a lithium ion battery before liquid is poured in. A lithium ion battery has an insulation resistance R and a capacitance C, and is represented by an equivalent circuit in which these are connected in parallel.

[0021] In the first embodiment, the positive electrode (+) of the detection object 1 is connected to the connection terminal 101 of the short-circuit detection device 100, and the negative electrode (-) of the detection object 1 is connected to the connection terminal 102 of the short-circuit detection device 100.

[0022] The short circuit detection device 100 includes a power supply unit 110, a voltage measurement unit 120, a current measurement unit 130, a fluctuation detection circuit 140, an AD converter 150, a processing unit 200, a display unit 210, and an operation reception unit 220. The power supply unit 110 and the processing unit 200 constitute a supply means that charges the detection object 1 with a current controlled to maintain a predetermined current value until the voltage of the detection object 1 reaches a predetermined voltage value. Hereinafter, the predetermined voltage value is referred to as V1, and the predetermined current value is referred to as I1.

[0023] The power supply unit 110 is a circuit that generates an electric signal and supplies the electric signal to the detection target 1, and constitutes a part of the supply means described above. The power supply unit 110 has, as its functions, a current limiter 10, a constant current source 11, a constant voltage source 12, and a switch unit 13.

[0024] The current limiter 10 is connected to the output terminal of the constant voltage source 12. The current limiter 10 limits the current supplied from the constant voltage source 12 to the object 1 to be detected in accordance with an instruction from the processing unit 200.

[0025] The constant current source 11 constitutes a constant current supply means that supplies a current I controlled to maintain a current value I1, i.e., a constant current controlled current, to the object of detection 1. The constant current source 11 charges the object of detection 1 by supplying a constant DC current to the positive electrode (+) of the object of detection 1 via a connection terminal 101 of the short circuit detection device 100.

[0026] Constant voltage source 12 constitutes a constant voltage supply means that supplies a voltage V controlled to maintain a voltage value V1 to object to be detected 1. Constant voltage source 12 supplies a constant DC voltage between the positive and negative electrodes of object to be detected 1 via connection terminal 101 in order to detect leakage current of object to be detected 1.

[0027] The switch unit 13 switches the power source connectable to the object of detection 1 between the current limiter 10 and the constant voltage source 12. In accordance with a command from the processing unit 200, the switch unit 13 connects the positive electrode (+) of the object of detection 1 to the constant current source 11, and switches the power source connected to the object of detection 1 from the constant current source 11 to the constant voltage source 12 via the current limiter 10 after charging of the object of detection 1 is completed.

[0028] The voltage measurement unit 120 constitutes a measurement means for measuring the magnitude of a signal generated in the detection object 1. In particular, the voltage measurement unit 120 constitutes a voltage measurement means for measuring the magnitude of a voltage generated in the detection object 1.

[0029] The voltage measurement unit 120 in the first embodiment measures the magnitude of the voltage generated between the positive electrode (+) and the negative electrode (-) of the object to be detected 1 as a signal indicating the magnitude of the voltage generated in the object to be detected 1. The current measurement unit 130 then outputs to the AD converter 150 a voltage detection signal Vv obtained by filtering the measurement signal indicating the magnitude of the measured voltage.

[0030] The current measuring unit 130 constitutes a measuring means for measuring the magnitude of a signal generated in the detection target 1. In particular, the current measuring unit 130 constitutes a current measuring means for measuring the magnitude of a current flowing through the detection target 1 as a signal generated in the detection target 1.

[0031] The current measuring unit 130 in the first embodiment measures the magnitude of the leakage current output from the negative electrode (-) of the object to be detected 1 as a signal indicating the magnitude of the current flowing through the object to be detected 1. Then, the current measuring unit 130 outputs a current detection signal Vi indicating the magnitude of the measured current to the AD converter 150.

[0032] For example, the magnitude of the leakage current is about milliamperes (mA) when the detection object 1 is being charged by the constant current source 11. On the other hand, when the voltage of the detection object 1 is controlled by the constant voltage source 12 to maintain a voltage value V1, the magnitude of the leakage current is about nanoamperes (nA) or microamperes (μA).

[0033] The current measuring unit 130 is configured by, for example, an IV conversion circuit that converts an input current into a voltage. The current measuring unit 130 also generates a measurement signal Vmi that indicates the magnitude of the current output from the negative electrode (-) of the detection object 1, and outputs the generated measurement signal Vmi to the fluctuation detection circuit 140.

[0034] The fluctuation detection circuit 140 detects fluctuations in the measurement signal Vmi caused by a short circuit occurring in the detection object 1. The fluctuation detection circuit 140 in the first embodiment detects temporary fluctuations in the measurement signal Vmi caused by a short circuit caused by the inclusion of a foreign substance in the detection object 1.

[0035] The fluctuation detection circuit 140 generates, as fluctuation detection signals indicating the detected fluctuation, a first hold signal Vh1 that holds the peak of the measurement signal Vmi, and a second hold signal Vh2 that holds the peak of the difference between the measurement signal Vmi and the first hold signal Vh1. The fluctuation detection circuit 140 outputs the generated fluctuation detection signals to the AD converter 150. An example configuration of the fluctuation detection circuit 140 will be described later with reference to FIG. 2.

[0036] The AD converter 150 samples the voltage detection signal Vv at a predetermined cycle and outputs voltage measurement data generated by the sampling to the processing unit 200. The AD converter 150 samples the current detection signal Vi from the current measuring unit 130 at a predetermined cycle and outputs current measurement data generated by the sampling to the processing unit 200.

[0037] Similarly, the AD converter 150 samples the fluctuation detection signal from the fluctuation detection circuit 140 at a predetermined cycle, and outputs fluctuation detection data generated by the sampling to the processing unit 200 .

[0038] The processing unit 200 constitutes a part of the supply means described above. In this supply means, the processing unit 200 constitutes a control means that charges the detection target 1 with the constant current source 11 and then controls the constant voltage source 12 so that the voltage of the detection target 1 is maintained at a predetermined voltage value V1.

[0039] The processing unit 200 is a computer configured with a processor, a ROM (Read Only Memory), a RAM (Random Access Memory), a mass storage device, an input / output interface, and a bus interconnecting these components. Examples of the processor include a CPU (Central Processing Unit) or an MPU (Micro Processor Unit). Examples of the mass storage device include an HDD (Hard Disk Drive) or an SSD (Solid State Drive).

[0040] The processing unit 200 controls the current limiter 10 , the constant current source 11 , the constant voltage source 12 , and the switch unit 13 that constitute the power supply unit 110 .

[0041] In the first embodiment, the processing unit 200 acquires a voltage detection signal Vv indicating a voltage value of the detection object 1 from the voltage measurement unit 120 via the AD converter 150. Furthermore, the processing unit 200 acquires a current detection signal Vi indicating a current value of the detection object 1 from the current measurement unit 130 via the AD converter 150. Then, the processing unit 200 controls the operation of the power supply unit 110 based on the voltage detection signal Vv and the current detection signal Vi.

[0042] The processing unit 200 controls the connection of the switch unit 13 so as to connect the constant current source 11 to the positive electrode (+) of the detection object 1. Thereafter, the processing unit 200 controls the driving of the constant current source 11 based on the current detection signal Vi so as to maintain a constant current I that is charged from the constant current source 11 to the detection object 1. That is, the processing unit 200 in the first embodiment performs constant current control using the constant current source 11.

[0043] At this time, the processing unit 200 determines whether or not the voltage generated between the positive electrode (+) and the negative electrode (-) of the detection object 1 has reached the voltage value V1 based on the voltage detection signal Vv.

[0044] When the voltage of the object to be detected 1 reaches a voltage value V1, the processing unit 200 controls the connection of the switch unit 13 to switch the power supply connected to the object to be detected 1 from the constant current source 11 to the current limiter 10 connected to the constant voltage source 12.

[0045] Thereafter, the processing unit 200 controls the driving of the constant voltage source 12 based on the voltage detection signal Vv so that the voltage generated between the two electrodes of the detection object 1 maintains the voltage value V1. That is, the processing unit 200 in the first embodiment performs constant voltage control using the constant voltage source 12.

[0046] In addition, the processing unit 200 executes a short circuit detection process to detect a short circuit occurring in the detection object 1. When the processing unit 200 receives a request signal requesting execution of the short circuit detection process from the operation receiving unit 220, for example, the processing unit 200 executes the short circuit detection process.

[0047] In the above-described short circuit detection process, the processing unit 200 outputs a supply command signal to supply a voltage of a voltage value V1 to the detection object 1. Then, upon receiving the supply command signal, the processing unit 200 controls the operation of the power supply unit 110 so as to charge the detection object 1 with a current I and continue to supply a voltage of a voltage value V1 to the detection object 1.

[0048] With power being supplied from the power supply unit 110 to the detection object 1, the processing unit 200 acquires voltage measurement data, current measurement data, and fluctuation detection data from the AD converter 150. Then, the processing unit 200 determines whether or not a short circuit has occurred due to an abnormality that may occur in the detection object 1, based on the fluctuation detection data.

[0049] Furthermore, the processing unit 200 calculates the physical quantity of the detection object 1 based on the acquired current measurement data or voltage measurement data. For example, the physical quantity of the detection object 1 may be the leakage current of the detection object 1 and the insulation resistance R of the detection object 1. The processing unit 200 outputs the determination result or calculation result indicating the presence or absence of a short circuit to the display unit 210.

[0050] The display unit 210 generates and displays image data representing the determination result or calculation result output from the processing unit 200. For example, the display unit 25 is configured by an LED display, a liquid crystal panel, a touch panel, or the like.

[0051] The operation reception unit 220 receives an input operation from the user and outputs an operation signal indicating the received input operation to the processing unit 200. The operation reception unit 220 is configured by, for example, a push button provided near the screen of the display unit 210, a touch sensor built into a touch panel, or a keyboard and a mouse.

[0052] For example, the operation receiving unit 220 receives a user operation to press an execution button for short circuit detection processing, thereby outputting the above-mentioned short circuit detection request to the processing unit 200. As a result, the short circuit detection device 100 executes the short circuit detection processing.

[0053] Next, the configuration of the fluctuation detection circuit 140 will be described with reference to FIGS.

[0054] FIG. 2 is a circuit diagram showing an example of the circuit configuration of the current measuring unit 130 and the fluctuation detecting circuit 140 in the first embodiment.

[0055] The current measuring unit 130 includes an IV conversion circuit 131 and a filter circuit 132 .

[0056] The IV conversion circuit 131 converts into a voltage signal a current signal of the detection object 1 input from the connection terminal 102 of the short circuit detection device 100. The converted voltage signal changes in proportion to the magnitude of the current signal, for example.

[0057] The IV conversion circuit 131 outputs the converted voltage signal to the fluctuation detection circuit 140 as a measurement signal Vmi indicating the magnitude of the current flowing through the detection object 1. That is, the measurement signal Vmi is generated by the current measurement unit 130. The IV conversion circuit 131 also outputs the converted voltage signal to the filter circuit 132.

[0058] The filter circuit 132 removes noise components from the voltage signal output from the IV conversion circuit 131. The filter circuit 132 is configured with, for example, a low-pass filter (LPF). The filter circuit 132 outputs the voltage signal from which the high-frequency components have been removed to the AD converter 150 as the above-mentioned current detection signal Vi.

[0059] The fluctuation detection circuit 140 includes a maximum value holding circuit 140A and a fluctuation holding circuit 140B.

[0060] The maximum value holding circuit 140A constitutes a first holding circuit that holds a peak indicating the maximum value of the measurement signal Vmi generated by the current measuring unit 130. The maximum value holding circuit 140A outputs a first held signal Vh1 indicating the peak of the held measurement signal Vmi to the AD converter 150 and the fluctuation holding circuit 140B. The maximum value holding circuit 140A is constituted by a peak hold circuit 141.

[0061] The fluctuation holding circuit 140B holds the fluctuation of the measurement signal Vmi output from the IV conversion circuit 131. In the first embodiment, the fluctuation holding circuit 140B constitutes a second holding circuit that holds the peak of a differential signal indicating the difference between the measurement signal Vmi and the first held signal Vh1. The fluctuation holding circuit 140B outputs a second held signal Vh2 that indicates the peak of the held differential signal.

[0062] The fluctuation holding circuit 140B includes a subtraction circuit 142 and a peak hold circuit 143.

[0063] The subtraction circuit 142 generates a differential signal by subtracting the measurement signal Vmi from the first hold signal Vh1. The subtraction circuit 142 outputs the generated differential signal to the peak hold circuit 143.

[0064] The peak hold circuit 143 holds the peak of the differential signal output from the subtraction circuit 142. The peak hold circuit 143 outputs a second hold signal Vh2 indicating the peak of the differential signal to the AD converter 150 as the fluctuation detection signal described above.

[0065] FIG. 3 is a circuit diagram showing an example of the circuit configuration of the peak hold circuits 141 and 143. As shown in FIG.

[0066] The peak hold circuits 141 and 143 in the first embodiment have a general circuit configuration, and include operational amplifiers 41 and 42, diodes 43 and 44, resistive elements 45 to 47, capacitive elements 48 and 49, and a reset switch 50.

[0067] The reset switch 50 is a switch for resetting the potential held in the capacitive element 49, and is controlled by, for example, the processing unit 200. The reset switch 50 is temporarily switched from a cut-off state to a conducting state when, for example, charging of the detection target 1 is completed.

[0068] Next, the operation of the fluctuation detection circuit 140 in the first embodiment will be described with reference to FIGS.

[0069] FIG. 4 is a diagram for explaining the relationship between the fluctuation of the measurement signal Vmi output from the IV conversion circuit 131 and the fluctuation detection data (Dh1, Dh2) output from the AD converter 150. As shown in FIG.

[0070] 4(a) shows an example of sampling processing of the measurement signal Vmi input to the fluctuation detection circuit 140. For ease of understanding, FIG. 4(a) assumes that the measurement signal Vmi temporarily rises or falls by 1 [V] from a reference voltage of 1 [V], and that the period of temporary fluctuation of the measurement signal Vmi is shorter than the sampling period Tp. In this example, the voltage of the measurement signal Vmi at sampling points Sp1 to Sp5 is 1 [V].

[0071] FIG. 4(b) shows voltage values ​​of the measurement data Dm, the first held data Dh1, and the second held data Dh2 at the sampling times Sp1 to Sp5.

[0072] The measurement data Dm and the fluctuation detection data (Dh1, Dh2) are data obtained by converting the measurement signal Vmi, the first held signal Vh1, and the second held signal Vh2 into digital signals by the AD converter 150. In the example shown in FIG. 4(b), for ease of understanding, the peak hold circuits 141 and 143 are reset immediately after the sampling times Sp1 to Sp5.

[0073] As shown in FIG. 4(b), when the measurement signal Vmi remains unchanged at 1 [V], the second held data Dh2 becomes 0 [V] at the sampling points Sp1 and Sp3.

[0074] In contrast, if the measurement signal Vmi temporarily rises or falls from 1 [V] during the sampling period Tp, the second retained data Dh2 will be 1 [V] at sampling points Sp4 and Sp5. Also, if the measurement signal Vmi temporarily rises and falls from 1 [V] during the sampling period Tp, the second retained data Dh2 will be 2 [V] at sampling point Sp2.

[0075] In this way, when the measurement signal Vmi temporarily fluctuates, the second held data Dh2 indicates a value greater than 0 V. In other words, the second held data Dh2 is data indicating whether or not the measurement signal Vmi fluctuates. Naturally, the same applies to the second held signal Vh2.

[0076] Therefore, the processing unit 200 shown in FIG. 1 can determine whether or not there is a short circuit caused by an abnormality occurring in the detection object 1, based on the second retained data Dh2 indicating whether or not there is a fluctuation in the measurement signal Vmi.

[0077] In detail, when the second retained data Dh2 exceeds the threshold value of 0 [V], the processing unit 200 determines that a short circuit has occurred in the detection object 1. On the other hand, when the second retained data Dh2 is 0 V, the processing unit 200 determines that a short circuit has not occurred in the detection object 1.

[0078] In other words, the processing unit 200 determines that a short circuit has occurred in the object to be detected 1 if the second retained data Dh2 exceeds a predetermined threshold, and determines that a short circuit has not occurred in the object to be detected 1 if the second retained data Dh2 does not exceed the predetermined threshold.

[0079] 4(b), when the first retained data Dh1 indicates 2 [V], this means that the measurement signal Vmi has temporarily increased. Therefore, by using the first retained data Dh1 in addition to the second retained data Dh2, it is possible to determine whether the fluctuation in the measurement signal Vmi is a temporary increase.

[0080] Specifically, when the processing unit 200 determines that a short circuit has occurred in the object to be detected 1 based on the second retained data Dh2, and the first retained data Dh1 indicates a value greater than the voltage value V1 indicating 1 [V], it determines that the measurement signal Vmi has temporarily increased.

[0081] On the other hand, when it is determined that a short circuit has occurred in the object to be detected 1 based on the second retained data Dh2, and the first retained data Dh1 shows the same value as the measurement data Dm, the processing unit 200 determines that the measurement signal Vmi has temporarily decreased.

[0082] In this way, when the processing unit 200 determines that a short circuit has occurred in the object to be detected 1 based on the second retained data Dh2, it can use the first retained data Dh1 to determine whether the measurement signal Vmi has temporarily increased or decreased.

[0083] FIG. 5 is a time chart for explaining a method for detecting fluctuations in the measurement signal Vmi during the charging period Tc of the detection target 1. In FIG.

[0084] In Fig. 5(a), the solid line indicates the time change in the voltage generated between the positive and negative electrodes of the object to be detected 1, and the dotted line indicates the time change in the leakage current output from the negative electrode (-) of the object to be detected 1. Fig. 5(b) shows the time change in the first hold signal Vh1, and Fig. 5(c) shows the time change in the second hold signal Vh2. The horizontal axis in Figs. 5(a) to 5(c) is a common time axis and indicates the elapsed time from the point in time when charging of the object to be detected 1 began.

[0085] 5(a), the voltage of the detection object 1 increases over time as a result of the supply of current I, which is controlled to be kept constant at a current value I1, from constant current source 11 during the charging period Tc, and reaches a voltage value V1 at switching time T1. The voltage of the detection object 1 is then controlled by constant voltage source 12 during the steady period Ts to be kept constant.

[0086] 5(a), the leakage current of the detection object 1 is controlled by the constant current source 11 during the charging period Tc so that the current I is maintained constant at a current value I1. When the control of the power supply to the detection object 1 switches from constant current control to constant voltage control at the switching time T1, the leakage current of the detection object 1 during the steady period Ts decreases below the current value I1 and is controlled to be maintained constant at a specific current value.

[0087] In the example shown in Figure 5(a), temporary fluctuations in the electrical signal occur during the charging period Tc and the steady-state period Ts. The voltage fluctuations shown by the solid lines and the current fluctuations shown by the dotted lines follow Ohm's law, so the directions of the fluctuations are opposite to each other. In this example, constant current control is performed using constant current source 11 during the charging period Tc, and constant voltage control is performed using constant voltage source 12 during the steady-state period Ts.

[0088] Therefore, during the charging period Tc, constant current control is performed so that the leakage current value of the detection object 1 is constant, so that current fluctuations of the detection object 1 are smaller than voltage fluctuations. On the other hand, during the steady-state period Ts, constant voltage control is performed so that the voltage value of the detection object 1 is constant, so that voltage fluctuations of the detection object 1 are smaller than current fluctuations.

[0089] 5(a), when a temporary drop in the voltage of the detection object 1 occurs during a fluctuation period Tv within a sampling period Tp during a charging period Tc, a temporary increase in the leakage current of the detection object 1 occurs. Therefore, the measurement signal Vmi temporarily drops in the same manner as the temporary drop in the voltage of the detection object 1. Note that the polarity of the measurement signal Vmi in the first embodiment is inverted by the IV conversion circuit 131 as shown in FIG.

[0090] At this time, as shown in FIG. 5(b), the first hold signal Vh1 rises from the point at which the measurement signal Vmi temporarily rises, and then indicates +1 [V].

[0091] On the other hand, as shown in FIG. 5(c), the second hold signal Vh2, which indicates the peak of the difference signal (Vh1-Vmi) obtained by subtracting the measurement signal Vmi from the first hold signal Vh1, continues to indicate +0.1 [V].

[0092] Therefore, even if a fluctuation occurs in the measurement signal Vmi during the sampling period Tp, the second hold signal Vh2 continues to indicate +0.1 [V], so that the voltage fluctuation of the detection target 1 can be detected correctly.

[0093] That is, in the fluctuation detection circuit 140 of the first embodiment, even if the fluctuation period Tv of the measurement signal Vmi caused by a short circuit in the detection object 1 is shorter than the sampling period Tp, it is possible to detect the fluctuation of the measurement signal Vmi without shortening the sampling period Tp. Therefore, it is possible to determine whether or not a short circuit may occur in the detection object 1 while a voltage is being supplied to the detection object 1.

[0094] In this way, by providing the short circuit detection device 100 with the fluctuation detection circuit 140, fluctuations in the measurement signal Vmi can be detected not only during the steady-state period Ts in which the voltage of the object to be detected 1 is controlled to maintain the voltage value V1, but also during the charging period Tc in which the current of the object to be detected 1 is being charged with a current I controlled to maintain the current value I1.

[0095] Therefore, it is possible to detect fluctuations in the measurement signal Vmi even if the charging period Tc of the detection object 1 is changed as needed. Therefore, the short circuit detection device 100 of the first embodiment is configured to be able to change the magnitude of the current value I1 supplied to the detection object 1 during the charging period Tc.

[0096] Although the method for detecting the fluctuation of the measurement signal Vmi during the charging period Tc has been described above, the fluctuation of the measurement signal Vmi during the steady period Ts can also be detected in the same way.

[0097] Next, the operation of the processing unit 200 will be described with reference to FIG.

[0098] The processing unit 200 in the first embodiment constitutes a current control means that controls the current supplied to the detection object 1 by the power supply unit 110 to be constant based on the difference between an upper limit value for limiting the current I to a current value I1 and the current detection signal Vi. The upper limit value is stored in the internal memory of the processing unit 200 by the operation receiving unit 220 in accordance with, for example, a user operation.

[0099] 1 so that the rate of increase per unit time of the voltage generated in the detection object 1 during the charging period Tc is a different value. That is, the processing unit 200 can change the magnitude of the current value I1 of the current I supplied from the constant current source 11 to the detection object 1 so that the rate of increase per unit time of the voltage generated in the detection object 1 becomes larger or smaller.

[0100] 1, the processing unit 200 acquires from an internal memory an upper limit value of the current supplied from the constant current source 11 to the detection object 1. For example, the upper limit value is determined according to the sampling period Tp of the measurement signal Vmi.

[0101] FIG. 6 is a diagram showing a change in voltage generated between the two electrodes (positive and negative electrodes) of the detection object 1 due to an electric signal supplied from the power supply unit 110. In FIG.

[0102] In Fig. 6, the voltage characteristics of the detection object 1 shown in Fig. 5 are shown by a dashed line. Furthermore, in Fig. 6, the voltage characteristics of the detection object 1 when the upper limit value for limiting the current I to the current value I1 is increased relative to the measurement conditions in Fig. 5 are shown by a dashed line, and the voltage characteristics of the detection object 1 when the upper limit value is decreased are shown by a solid line.

[0103] As shown in FIG. 6, the processing unit 200 can change the time rate of change of the voltage generated between the two electrodes of the detection target 1 during the charging period Tc.

[0104] In this way, by reducing the current value I1 supplied from the constant current source 11 to the detection object 1, the rate of increase per unit time of the voltage generated in the detection object 1 can be reduced.

[0105] It is also possible to estimate the time rate of change of the voltage generated in the detection object 1 based on the upper limit value for maintaining the current I at the current value I1. In this case, the actual measured value, estimated value, or representative value of the capacitance C of the detection object 1 is known, and the time rate of change ΔV is calculated by the following equation using the upper limit value Imax and the capacitance C. ΔV=Imax / C

[0106] The processing unit 200 can detect voltage fluctuations caused by a short circuit in the object to be detected 1 by comparing the estimated value of the time rate of change ΔV based on the upper limit value Imax with the actual measured value of the time rate of change ΔV of the voltage detection signal Vv.

[0107] As a specific example, a table showing the relationship between the upper limit value Imax and the time rate of change ΔV of voltage is stored in advance in the internal memory of the processing unit 200. When the processing unit 200 acquires the upper limit value Imax selected by a user operation, it reads from the internal memory an estimated value of the time rate of change ΔV corresponding to that upper limit value. Thereafter, the processing unit 200 determines that a voltage fluctuation has occurred when the time rate of change ΔV of the voltage detection signal Vv deviates from the estimated value by a predetermined value or more.

[0108] Next, the operation of the short circuit detection device 100 will be described with reference to FIGS.

[0109] 7 is a flowchart showing a short circuit detection method by the short circuit detection device 100. First, the processing unit 200 constituting the short circuit detection device 100 outputs the above-mentioned supply command signal to the processing unit 200 in accordance with, for example, an input operation by the user.

[0110] In step S1, the processing unit 200 drives the constant current source 11 and the constant voltage source 12 upon receiving a supply command signal.

[0111] In step S2, the processing unit 200 further acquires the upper limit of the current to be supplied to the detection target 1 from the internal memory.

[0112] In step S3, the processing unit 200 sets the connection of the switch unit 13 to the constant current source 11, and supplies a current I from the constant current source 11 to the detection object 1 so that the current value becomes a current value I1. As a result, the processing unit 200 charges the detection object 1 with a constant current having a current value I1.

[0113] At this time, the processing unit 200 controls the operation of the constant current source 11 in accordance with the difference between the current detection signal Vi and the upper limit value for limiting the current I to the current value I1. Therefore, the power supply unit 110 functions as the constant current source 11.

[0114] In step S4, the current measuring unit 130 measures a signal generated in the detection object 1 by the power supply unit 110 functioning as the constant current source 11. In the first embodiment, the current measuring unit 130 measures the magnitude of the current output from the negative electrode (-) of the detection object 1. Then, the current measuring unit 130 generates a measurement signal Vmi indicating the magnitude of the leakage current.

[0115] In step S5, the short circuit detection device 100 executes a fluctuation detection process to detect fluctuations in the signal occurring in the detection object 1. A specific example of the fluctuation detection process will be described later with reference to FIG.

[0116] In step S6, when the voltage generated across the detection object 1 reaches the voltage value V1, the processing unit 200 switches the connection of the switch unit 13 to the constant voltage source 12, and applies the voltage value V1 from the constant voltage source 12 to the detection object 1 so that the voltage generated across the detection object 1 is maintained constant. At this time, the processing unit 200 controls the operation of the power supply unit 110 in accordance with the voltage detection signal Vv. Therefore, the power supply unit 110 functions as the constant voltage source 12.

[0117] In step S7, the current measuring unit 130 measures a signal generated in the detection object 1 by the power supply unit 110 functioning as the constant voltage source 12. In the first embodiment, the current measuring unit 130 measures the magnitude of the current output from the negative electrode (-) of the detection object 1. Then, the current measuring unit 130 generates a measurement signal Vmi indicating the magnitude of the leakage current.

[0118] In step S8, the short circuit detection device 100 executes a fluctuation detection process to detect fluctuations in the signal occurring in the detection object 1. A specific example of the fluctuation detection process will be described later with reference to FIG.

[0119] In step S9, the processing unit 200 determines whether or not there is a fluctuation in the measurement signal Vmi due to a short circuit in the detection object 1, based on the fluctuation detection signal generated by executing the fluctuation detection processes in steps S5 and S8. If there is a fluctuation in the measurement signal Vmi, the processing unit 200 determines that a short circuit has occurred, and if there is no fluctuation in the measurement signal Vmi, it determines that a short circuit has not occurred.

[0120] At the same time, the processing unit 200 measures the physical quantity of the detection object 1 based on a signal generated in the detection object 1. In the first embodiment, the processing unit 200 calculates the leakage current or insulation resistance R of the detection object 1 based on a current detection signal Vi indicating the magnitude of the current output from the negative electrode (-) of the detection object 1. For example, the insulation resistance R is found based on the calculated leakage current and the voltage value between the positive and negative electrodes of the detection object 1.

[0121] When the process of step S9 is completed, the series of process steps related to the short circuit detection method is completed. In this way, the presence or absence of a short circuit that may occur in the detection object 1 can be detected while measuring the physical quantity of the detection object 1.

[0122] FIG. 8 is a flowchart showing an example of a processing procedure for the fluctuation detection processing executed in steps S5 and S8.

[0123] In step S51, the fluctuation detection circuit 140 holds the peak of the measurement signal Vmi, which indicates the magnitude of the current flowing through the detection object 1, from the IV conversion circuit 131. Then, the fluctuation detection circuit 140 generates a first hold signal Vh1 indicating the held peak value.

[0124] In step S52, the fluctuation detection circuit 140 generates a differential signal by subtracting the measurement signal Vmi from the first held signal Vh1.

[0125] In step S53, the fluctuation detection circuit 140 holds the peak of the generated differential signal. The fluctuation detection circuit 140 then generates a second hold signal Vh2 that indicates the held peak value. As shown in FIG. 4, the second hold signal Vh2 indicates 0 [V], which is the reference level, if no temporary fluctuation occurs in the measurement signal Vmi, and indicates a value higher than the reference level if a temporary fluctuation occurs.

[0126] In step S54, the fluctuation detection circuit 140 outputs the second hold signal Vh2 as a fluctuation detection signal indicating whether or not there is a fluctuation in the measurement signal Vmi.

[0127] When the process of step S54 is completed, the series of processing procedures for the fluctuation detection processing executed in steps S5 and S8 is completed, and the process returns to the processing procedures of the short circuit detection method shown in FIG.

[0128] Next, the effects of the first embodiment will be described.

[0129] In the first embodiment, the short circuit detection device 100 is a device for detecting a short circuit occurring in the detection object 1. This short circuit detection device 100 includes a power supply unit 110 (supply means) that charges the detection object 1 with a current I that is controlled to be constant current until the voltage of the detection object 1 reaches a voltage value V1 that corresponds to a predetermined voltage value, and a current measurement unit 130 (measurement means) that measures the current that flows through the detection object 1 as a signal generated in the detection object 1 by the power supply unit 110.

[0130] The short-circuit detection device 100 further includes a maximum value holding circuit 140A (first holding circuit) that holds the peak of the measurement signal Vmi generated by the current measurement unit 130 and outputs a first held signal Vh1 that indicates the peak of the held measurement signal Vmi. The short-circuit detection device 100 also includes a fluctuation holding circuit 140B (second holding circuit) that holds the peak of a differential signal that indicates the difference between the measurement signal Vmi and the first held signal Vh1 and outputs a second held signal Vh2 that indicates the peak of the held differential signal.

[0131] The short circuit detection device 100 also includes a processing unit 200 (determination means) that determines whether or not there is a fluctuation in the measurement signal Vmi due to a short circuit in the detection object 1 based on the second held signal Vh2 output from the fluctuation holding circuit 140B.

[0132] According to this configuration, by using the maximum value holding circuit 140A and the fluctuation holding circuit 140B, it is possible to detect fluctuations in the measurement signal Vmi, and therefore it is possible to detect both temporary increases and decreases in the measurement signal Vmi due to a short-term short circuit caused by the inclusion of foreign matter, etc. Therefore, it is possible to detect a short circuit caused by an abnormality occurring in the detection object 1 without high-speed sampling of the measurement signal Vmi of the detection object 1.

[0133] In particular, even if the period during which the measurement signal Vmi temporarily fluctuates is shorter than the sampling period Tp, the fluctuation can be accurately detected. Therefore, there is little need to replace the AD converter 150, the processing unit 200, etc. with high-precision circuits so that the sampling period Tp falls within the fluctuation period Tv of the measurement signal Vmi, and therefore the production cost can be reduced while maintaining the detection accuracy of the short-circuit detection device 100.

[0134] Furthermore, since there is little need to consider the fluctuation period Tv of the measurement signal Vmi, it is possible to change the magnitude of the current value I1 supplied from the constant current source 11 of the power supply unit 110 to the detection object 1 as needed. For example, it is possible to shorten the charging period Tc by increasing the current value I1.

[0135] Furthermore, when the processing unit 200 in the first embodiment determines based on the second hold signal Vh2 that there is a fluctuation in the measurement signal Vmi, it determines based on the first hold signal Vh1 whether the fluctuation in the measurement signal Vmi is a temporary increase or a temporary decrease. With this configuration, the fluctuation pattern of the measurement signal Vmi is identified, making it easier to identify the cause of the fluctuation.

[0136] Note that if the object to be detected 1 is shorted from start to finish, it is not possible to detect a short circuit using only the first hold signal Vh1 indicating the peak of the measurement signal Vmi and the second hold signal Vh2 indicating the peak of the differential signal between the measurement signal Vmi, because there is no fluctuation in the measurement signal Vmi. However, by determining whether the magnitude of the first hold signal Vh1 indicating the peak of the measurement signal Vmi is close to 0, it is possible to determine whether the object to be detected 1 is shorted from start to finish, so it is possible to detect a short circuit even if the object to be detected 1 is shorted from start to finish. In this way, by combining the first hold signal Vh1 and the second hold signal Vh2, it is possible to determine whether the object to be detected 1 is shorted from start to finish of the detection process.

[0137] The fluctuation holding circuit 140B in the first embodiment has a subtraction circuit 142 that outputs a differential signal obtained by subtracting the measurement signal Vmi from the first held signal Vh1, and a peak hold circuit 143 that holds the peak of the differential signal output from the subtraction circuit 142.

[0138] According to this configuration, by configuring the fluctuation holding circuit 140B with the subtraction circuit 142 and the peak hold circuit 143, the fluctuation holding circuit 140B can be realized with a simple configuration and at low cost.

[0139] The power supply unit 110 (supply means) in the first embodiment includes a constant current source 11 (constant current means) that supplies a constant current controlled current I to the object to be detected 1, and a constant voltage source 12 (constant voltage means) that supplies a voltage V of a predetermined voltage value V1 to the object to be detected 1. The processing unit 200 further includes, as supply means, a control means that charges the object to be detected 1 with the constant current source 11 and then causes the constant voltage source 12 to maintain the voltage value V1 of the object to be detected 1.

[0140] According to this configuration, either the predetermined current value I1 or the voltage value V1 is controlled to be kept constant, making it easier to extract fluctuations in the measurement signal Vmi and improving the accuracy of detecting short-term short circuits.

[0141] The measurement signal Vmi in the first embodiment is generated by the current measurement unit 130 and indicates the magnitude of the current flowing through the detection target 1.

[0142] For example, when constant voltage control is performed on the detection object 1 during the steady period Ts, as shown in Fig. 5(a), the fluctuation of the measurement signal Vmi, which indicates the magnitude of the current flowing through the detection object 1, becomes larger than the measurement signal Vmv, which indicates the magnitude of the voltage between the two electrodes of the detection object 1. Therefore, temporary fluctuations caused by a short circuit can be detected with high accuracy.

[0143] Furthermore, when the measurement signal Vmi is used, temporary fluctuations occur in the measurement signal Vmi at a constant signal level, as shown by the dashed line in Fig. 5(a). In contrast, when the measurement signal Vmv indicating the voltage of the detection target 1 measured by the voltage measurement unit 120 is used, temporary fluctuations occur while the signal level is rising at a constant rate, as shown by the solid line in Fig. 5(a), and the temporary fluctuations are partially obscured by the voltage rise.

[0144] Therefore, when a constant current is simply supplied to the object to be detected 1 without performing constant current control during the charging period Tc, temporary fluctuations can be detected more accurately by using the measurement signal Vmi than by using the measurement signal Vmv.

[0145] Furthermore, the processing unit 200 in the first embodiment can set the current value I1 to different values ​​so that the rate of increase per unit time of the voltage generated in the detection object 1 by the constant current source 11 changes.

[0146] This configuration makes it possible to reduce the rate of increase per unit time of the voltage occurring in the detection object 1. In this case, as the rate of increase per unit time of the voltage occurring in the detection object 1 decreases, the accuracy of detecting a short circuit can be improved for a detection object 1 that may be prone to an abnormality (foreign matter contamination) that makes the measurement signal Vmi more likely to temporarily fluctuate as the rate of increase per unit time of the voltage occurring in the detection object 1 decreases.

[0147] Conversely, it is also possible to increase the rate of increase per unit time of the voltage generated in the detection object 1. In this case, the charging period Tc can be shortened, and therefore the measurement time can be shortened while maintaining the detection accuracy.

[0148] Moreover, in the first embodiment, the current measuring unit 130 outputs a current detection signal Vi indicating the magnitude of the current flowing through the detection object 1. Furthermore, the processing unit 200 controls the current supplied to the detection object 1 by the constant current source 11 to be constant, based on the difference between the current detection signal Vi output from the current measuring unit 130 and an upper limit value for controlling the current I to the current value I1.

[0149] The upper limit value obtained by the processing unit 200 is changeable.

[0150] According to this configuration, the upper limit for making the current constant to indicate the current value I1 can be changed, so that the current value I1 supplied from the constant current source 11 to the detection object 1 can be changed arbitrarily.

[0151] For example, by increasing the upper limit, the current value I1 increases, and the charging period Tc shortens as shown in the voltage characteristics indicated by the dashed dotted line in Figure 6. Therefore, the tact time required for measurement can be shortened.

[0152] Furthermore, when an object such that the smaller the current value I1 is made, the more likely fluctuations in the measurement signal Vmi are to occur, is used as the detection target 1, it is also possible to reduce the upper limit value. This reduces the current value I1, making it possible to accurately detect fluctuations in the measurement signal Vmi.

[0153] In the first embodiment, the upper limit is determined according to the sampling period Tp of the measurement signal Vmi. For example, if the fluctuation period Tv of the measurement signal Vmi is longer than the sampling period Tp, the upper limit is increased to shorten the charging period Tc, and if the fluctuation period Tv is longer than the sampling period Tp, the upper limit is decreased to improve detection accuracy.

[0154] In addition, in the first embodiment, the short circuit detection method for detecting a short circuit occurring in the object to be detected 1 includes a supply step (S3) of charging the object to be detected 1 with a current I controlled to maintain a predetermined current value I1 until the voltage of the object to be detected 1 reaches a voltage value V1, and measurement steps (S4, S7) of measuring a signal occurring in the object to be detected 1 by the supply step (S3).

[0155] The short circuit detection method further includes a first holding step (S51) of holding the peak of the measurement signal Vmi generated in the measurement steps (S4, S7) and outputting a first holding signal Vh1 indicating the peak of the held measurement signal Vmi, and a second holding step (S52 to S54) of holding the peak of a differential signal indicating the difference between the measurement signal Vmi and the first holding signal Vh1 and outputting a second holding signal Vh2 indicating the peak of the held differential signal.

[0156] The short circuit detection method further includes a determination step (S9) of determining whether or not there is a fluctuation in the measurement signal Vmi due to a short circuit, based on the second hold signal Vh2 output in the second hold step (S52 to S54).

[0157] According to this configuration, by holding the peak of the differential signal indicating the difference between the measurement signal Vmi and the first hold signal Vh1, it is possible to detect both a temporary rise and a temporary fall of the measurement signal Vmi caused by a short circuit caused by the inclusion of a foreign object, etc. Therefore, it is possible to detect a short circuit occurring in the detection object 1.

[0158] As shown in FIG. 5, the short circuit detection device 100 of the first embodiment detects a short circuit using the measurement signal Vmi indicating the magnitude of the leakage current of the object to be detected 1 during the charging period Tc. However, a short circuit may also be detected using the measurement signal Vmv indicating the voltage between the electrodes of the object to be detected 1.

[0159] Second Embodiment Therefore, an embodiment in which a short circuit that may occur in the detection object 1 is detected using a measurement signal Vmv indicating the inter-electrode voltage of the detection object 1 will be briefly described with reference to FIGS.

[0160] FIG. 9 is a block diagram showing the functional configuration of a short circuit detection device 100A according to the second embodiment.

[0161] The short circuit detection device 100A includes a fluctuation detection circuit 240 in addition to the configuration of the first embodiment shown in Fig. 1. Other configurations are the same as or equivalent to the configuration of the short circuit detection device 100, so the same reference numerals are used and redundant explanations will be omitted.

[0162] Similar to the current measuring unit 130, the voltage measuring unit 120 outputs a voltage detection signal Vv from which noise components have been removed by a filter circuit having an LPF, similar to the filter circuit 132 shown in Fig. 2. Furthermore, in order to detect short-term short circuits, the voltage measuring unit 120 in the second embodiment outputs the measurement signal Vmv from which noise components have not been removed by the filter circuit to the fluctuation detection circuit 240.

[0163] The fluctuation detection circuit 240 detects fluctuations in the measurement signal Vmv caused by a short circuit occurring in the detection object 1. The fluctuation detection circuit 240 in the second embodiment detects temporary fluctuations in the measurement signal Vmv caused by a short circuit associated with the inclusion of a foreign substance in the detection object 1.

[0164] The fluctuation detection circuit 240 generates, as fluctuation detection signals indicating the detected fluctuation, a first hold signal Vh3 that holds the peak of the measurement signal Vmv, and a second hold signal Vh4 that holds the peak of the difference between the measurement signal Vmv and the first hold signal Vh3.

[0165] The fluctuation detection circuit 240 outputs the generated first hold signal Vh3 and second hold signal Vh4 to the AD converter 150. The configuration of the fluctuation detection circuit 240 is the same as the configuration shown in FIG.

[0166] FIG. 10 is a diagram showing an example of detecting fluctuations in the measurement signal Vmv during the charging period Tc.

[0167] In Fig. 10(a), the solid line indicates the change over time in the measurement signal Vmv, and the dotted line indicates the change over time in the leakage current output from the object to be detected 1. Fig. 10(b) shows the change over time in the first hold signal Vh3, and Fig. 10(c) shows the change over time in the second hold signal Vh2. The horizontal axis in Figs. 10(a) to 10(c) is a common time axis, and indicates the elapsed time from the point in time when charging of the object to be detected 1 began.

[0168] As shown in FIG. 10(a), if a temporary drop in the voltage of the detection target 1 occurs during a fluctuation period Tv within a sampling period Tp during a charging period Tc, the measurement signal Vmv also temporarily drops.

[0169] At this time, as shown in FIG. 10(b), the first hold signal Vh3 rises until just before the measurement signal Vmv starts to fall, and then indicates +1 [V].

[0170] On the other hand, as shown in FIG. 10(c), the second hold signal Vh4, which indicates the peak of the difference signal (Vh3-Vmv) obtained by subtracting the measurement signal Vmv from the first hold signal Vh1, continues to indicate +0.2 [V].

[0171] Therefore, even if a fluctuation occurs in the measurement signal Vmv during the sampling period Tp, the second hold signal Vh4 continues to indicate +0.2 [V], so that the voltage fluctuation of the detection object 1 can be detected correctly.

[0172] If the configuration simply detects fluctuations in the measurement signal Vmv that measures the voltage between the two electrodes of the object to be detected 1 without using the fluctuation detection circuit 240, it may not be possible to detect fluctuations in the measurement signal Vmv during the charging period Tc.

[0173] For example, if a temporary increase occurs while the voltage of the object to be detected 1 is increasing at a constant rate, it is possible that the voltage of the object to be detected 1 will exceed the peak of the measurement signal Vmv within the sampling period Tp.

[0174] As in the above example, if the period from when a fluctuation in the measurement signal Vmv occurs to when the voltage of the object to be detected 1 exceeds the peak of the fluctuation is shorter than the sampling period Tp, it becomes difficult to correctly detect the voltage fluctuation in the object to be detected 1.

[0175] That is, in the fluctuation detection circuit 240 of the second embodiment, even if the fluctuation period Tv of the measurement signal Vmv caused by a short circuit in the detection object 1 is shorter than the sampling period Tp, it is possible to detect the fluctuation of the measurement signal Vmv without shortening the sampling period Tp. Therefore, it is possible to determine whether or not a short circuit may occur in the detection object 1 while a voltage is being supplied to the detection object 1.

[0176] In this way, by providing the short circuit detection device 100 with the fluctuation detection circuit 240, fluctuations in the measurement signal Vmv can be detected not only during the steady-state period Ts in which the voltage of the object to be detected 1 is controlled to maintain the voltage value V1, but also during the charging period Tc in which the object to be detected 1 is charged with a current I having a current value I1.

[0177] Although the method for detecting the fluctuations in the measurement signal Vmv during the charging period Tc has been described above, the fluctuations in the measurement signal Vmv during the steady period Ts can also be detected in the same way.

[0178] Next, the effects of the second embodiment will be described.

[0179] The short circuit detection device 100A in the second embodiment has the same or equivalent configuration as that in the first embodiment, and this configuration allows the same effects as those in the first embodiment to be obtained.

[0180] Furthermore, the second embodiment uses a measurement signal Vmv that indicates the inter-electrode voltage of the object to be detected 1. During the charging period Tc, the fluctuations in the measurement signal Vmv are not suppressed by constant current control, unlike the fluctuations in the measurement signal Vmi used in the fluctuation detection circuit 140 of the first embodiment. Therefore, the short circuit detection device 100A can detect a short circuit that may occur in the object to be detected 1 with higher accuracy than the first embodiment.

[0181] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

[0182] For example, the circuit configuration of the IV conversion circuit 131 shown in Fig. 2 is merely an example, and is not limited to this, as long as it has the function of converting the input current into a voltage of a magnitude corresponding to the current value. Similarly, the circuit configuration of the subtraction circuit 142 shown in Fig. 2 is merely an example, and is not limited to this.

[0183] Furthermore, the circuit configuration of the peak hold circuits 141 and 143 shown in FIG. 3 is merely an example, and is not limited to this as long as it is a circuit configuration that holds the peak of an electrical signal.

[0184] In the above embodiment, the positive electrode (+) of the object to be detected 1 is connected to the connection terminal 101 of the short-circuit detection device 100, and the negative electrode (-) of the object to be detected 1 is connected to the connection terminal 102 of the short-circuit detection device 100. However, either the positive electrode (+) or the negative electrode (-) of the object to be detected 1 and the exterior of the object to be detected 1 may be connected to the connection terminals 101 and 102 of the short-circuit detection device 100, respectively. [Explanation of symbols]

[0185] 1. Object to be detected 10 Current Limiter 11 Constant current source (constant current supply means) 12 Constant voltage source (constant voltage supply means) 110 Power supply section (supply means) 120 Voltage measurement unit (measurement means, voltage measurement means) 130 Current measurement section (measurement means, current measurement means) 140, 240 Fluctuation detection circuit 140A Maximum value holding circuit (first holding circuit) 140B Fluctuation holding circuit (second holding circuit) 142 Subtraction Circuit 141, 143 Peak hold circuit 150 AD converter 200 Processing section (supply means, determination means)

Claims

1. A short circuit detection device for detecting a short circuit occurring in a detection object, a supply means for charging the object to be detected with a current controlled to a constant current until the voltage of the object to be detected reaches a predetermined voltage value; a measuring means for measuring a signal generated in the object to be detected by the supplying means; a first holding circuit that holds a peak of the measurement signal generated by the measuring means and outputs a first held signal that indicates the held peak of the measurement signal; a second holding circuit that holds a peak of a differential signal indicating a difference between the measurement signal and the first held signal, and outputs a second held signal indicating the peak of the held differential signal; a determination means for determining whether or not the measurement signal fluctuates based on the second hold signal output from the second hold circuit; A short circuit detection device comprising:

2. 2. The short circuit detection device according to claim 1, When it is determined that there is a fluctuation in the measurement signal based on the second hold signal, the determination means determines whether the fluctuation in the measurement signal is a temporary increase or a temporary decrease based on the first hold signal. Short circuit detection device.

3. 3. The short circuit detection device according to claim 2, The second holding circuit a subtraction circuit that outputs the difference signal obtained by subtracting the measurement signal from the first held signal; a peak hold circuit that holds a peak of the difference signal output from the subtraction circuit. Short circuit detection device.

4. 4. The short circuit detection device according to claim 1, The supply means a constant current supply means for supplying the constant current controlled current to the object to be detected; a constant voltage supply means for supplying a constant voltage to the object to be detected; and a control means for controlling the voltage of the object to be detected by the constant voltage supply means so as to maintain the voltage of the object to be detected at the predetermined voltage value after the object to be detected is charged by the constant current supply means. Short circuit detection device.

5. 5. The short circuit detection device according to claim 4, The measurement signal indicates the magnitude of a current flowing through the object to be detected. Short circuit detection device.

6. 6. The short circuit detection device according to claim 5, The measuring means a current measuring means for measuring the magnitude of a current flowing through the object to be detected; and a voltage measuring means for measuring the magnitude of the voltage generated in the detection object. Short circuit detection device.

7. 6. The short circuit detection device according to claim 5, the control means sets the current value of the constant current controlled current to different values ​​so that the rate of increase per unit time of the voltage generated in the object to be detected by the constant current supply means changes. Short circuit detection device.

8. 7. The short circuit detection device according to claim 6, the measuring means outputs a current detection signal indicating the magnitude of the current flowing through the object to be detected; the control means controls the current supplied to the object to be detected by the constant current supply means to be constant based on a difference between the current detection signal and an upper limit value for making the current a predetermined constant current; The upper limit value is variable. Short circuit detection device.

9. 9. The short circuit detection device according to claim 8, the upper limit value is determined according to a sampling period of the measurement signal. Short circuit detection device.

10. A short circuit detection method for detecting a short circuit occurring in a detection object, comprising: a supply step of charging the object to be detected with a current controlled to be constant current until the voltage of the object to be detected reaches a predetermined voltage value; a measuring step of measuring a signal generated in the detection target by the supplying step; a first holding step of holding a peak of the measurement signal generated in the measuring step and outputting a first held signal indicating the held peak of the measurement signal; a second holding step of holding a peak of a differential signal indicating the difference between the measurement signal and the first held signal, and outputting a second held signal indicating the peak of the held differential signal; a determination step of determining whether or not there is a fluctuation in the measurement signal based on the second held signal output in the second holding step, Short circuit detection method.

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