Electric leakage detection method

Abstract

According to this disclosure, a technique is provided that enables detailed determination of leakage points at low cost and with ease. The leakage detection method disclosed herein includes: a total voltage measurement step, which measures the total voltage (V) of the potential difference between an open positive terminal (14a) capable of being connected to an external device and an open negative terminal (16a) capable of being connected to an external device. t The leakage voltage measurement process measures the leakage voltage (V) as the potential difference between the reference terminal (total negative terminal 16a) and the leakage point (third single cell 10C). L ); and the process of determining the leakage point, by calculating the leakage voltage (V) L ) relative to the total voltage (V t The ratio (V) L / V t This allows us to determine the location of the leakage. From this, we can deduce the number of individual cells present between the reference terminal and the leakage location, and pinpoint the exact location of the leakage.

Description

Technical Field

[0001] This invention relates to a leakage current detection method. More specifically, it relates to a leakage current detection method for detecting leakage points in a power supply unit consisting of multiple electrically connected power sources. Background Technology

[0002] Power sources such as secondary batteries and generators are sometimes used as power supply units formed by connecting multiple of them. These power supply units have very high output voltages and are therefore insulated from the ground wire for safety reasons. However, depending on the usage, leakage may occur due to power supply failure, the introduction of foreign objects (moisture, metal fragments, etc.), or other reasons that could cause the ground wire to become conductive with the power source. In such cases, it is necessary to identify the leakage point as early as possible for component replacement, removal of foreign objects, and other repairs. Therefore, leakage detection technology exists that uses the resistance of the insulation components of the power supply unit to detect leakage.

[0003] For example, Patent Document 1 discloses a leakage current detection circuit for electric vehicles. In Patent Document 1, a battery pack (power supply unit) having multiple secondary batteries (power sources) is used as the object of inspection. Furthermore, this leakage current detection circuit includes: a first leakage current detection switch connected to the high-voltage side of the battery pack; a second leakage current detection switch connected to the low-voltage side; a control circuit that alternately switches the first and second leakage current detection switches on and off; a leakage current detection resistor connected to the battery pack via the first and second leakage current detection switches, with its midpoint connected to ground; a voltage detection circuit that detects the leakage current voltage of the leakage current detection resistor compared to the high-voltage side and low-voltage side of ground; and an arithmetic circuit that calculates the output of the voltage detection circuit to detect leakage current. This leakage current detection circuit detects the first leakage current voltage when the first leakage current detection switch is on and the second leakage current detection switch is off. Additionally, the leakage current detection circuit detects the second leakage current voltage when the first leakage current detection switch is off and the second leakage current detection switch is on. Moreover, the operation circuit of the leakage current detection circuit detects the leakage resistance based on the first leakage voltage, the second leakage voltage, and the total voltage of the battery pack.

[0004] Another example of a leakage current detection circuit is disclosed in Patent Document 2. This Patent Document 2 also examines a battery pack. This leakage current detection circuit includes multiple circuit blocks, a resistor voltage detection circuit, a control circuit, and a leakage current identification circuit. The connection points between the multiple circuit blocks and multiple battery cells are connected, and these connection points are connected to ground via a series circuit of a measuring resistor and a switching element. The resistor voltage detection circuit detects the voltage of the measuring resistor in the circuit block. Furthermore, the control circuit controls the switching elements of each circuit block. Moreover, the leakage current identification circuit detects leakage current based on the detected voltage of the resistor voltage detection circuit. The leakage current detection circuit with the above structure sequentially switches the switching elements of the multiple circuit blocks on and off, detecting the circuit block in which the voltage of the measuring resistor is detected in the resistor voltage detection circuit. Thus, it is possible to identify the battery cell where leakage current has occurred.

[0005] Patent Document 1: Japanese Application Publication No. 2007-327856

[0006] Patent Document 2: Japanese Application Publication No. 2007-149561

[0007] However, the existing leakage current detection technologies mentioned above still have room for improvement, and efforts are being made to find a technology that can determine the leakage location in a low-cost, simple, and detailed manner.

[0008] For example, since only one voltage detection circuit is used, the technology described in Patent Document 1 can detect leakage at low cost and with ease. However, in the technology described in Patent Document 1, it is difficult to determine which part of the multiple secondary batteries (power sources) is leaking. Specifically, in the technology described in Patent Document 1, leakage is determined to have occurred if the calculated leakage resistance is less than a predetermined threshold. However, the technology described in Patent Document 1 does not perform detailed determination of the leakage location. Therefore, it is difficult to determine the leakage location that needs repair using only the technology described in Patent Document 1. That is, the technology described in Patent Document 1 requires the use of additional techniques to determine the detailed leakage location.

[0009] On the other hand, in the technology described in Patent Document 2, the on / off state of circuit blocks connected between multiple battery cells is switched sequentially, and leakage current is detected. This allows the leakage location to be determined on a per-battery-cell basis (multiple batteries connected in series). However, to determine the leakage location in detail for a given power level using this leakage detection technology, leakage detection circuit blocks need to be installed in multiple (e.g., around 100) power sources. Therefore, the technology described in Patent Document 2 also leads to increased complexity and cost of the leakage detection circuit. Summary of the Invention

[0010] This invention was made to solve the above-mentioned problems, and its purpose is to provide a technique that can determine the leakage point in detail at low cost and easily.

[0011] To achieve the above objectives, a leakage current detection method disclosed herein is provided.

[0012] The leakage current detection method disclosed herein detects leakage points in a power supply unit electrically connected to multiple power sources. This leakage current detection method includes: a leakage voltage measurement step, which calculates the leakage voltage V, which is the potential difference between a reference terminal connected to a predetermined location in the power supply unit and the leakage point. L The process of determining the leakage point is based on the leakage voltage V. L To determine the location of the leakage.

[0013] The leakage current detection method disclosed here focuses on the leakage current voltage V, which is the potential difference between a reference terminal connected at any location in the power supply unit and the leakage point. L The method. Specifically, when leakage occurs in a power supply unit with a typical structure at a location far from the reference terminal, the leakage voltage V is high because there are many power sources between the reference terminal and the leakage point. L The voltage increases. On the other hand, when leakage occurs at a location far from the reference terminal, the leakage voltage V increases because the amount of power present between the reference terminal and the leakage point is small. L It becomes lower. Therefore, by calculating the leakage voltage V... L This allows for the easy determination of the leakage point by inferring the amount of power present between the reference terminal and the leakage point. Furthermore, the leakage detection method disclosed herein detects the leakage point solely by measuring the potential difference (leakage voltage V) between the reference terminal and the leakage point. L By using this method, the location of the leakage current can be determined, thus eliminating the need to install leakage detection circuits at multiple power sources. As described above, the leakage detection method disclosed herein allows for the detailed and cost-effective determination of the leakage location.

[0014] Based on one form of the leakage current detection method disclosed here, a reference potential difference acquisition step is also included. In the above-mentioned reference potential difference acquisition step, a reference potential difference V is obtained, which is the potential difference between a first terminal connected to a predetermined position in the power supply unit and a second terminal connected to a position with a potential different from that of the first terminal. S In the leakage voltage measurement process, either the first terminal or the second terminal is selected as the reference terminal, and the leakage voltage V, which is the potential difference between the reference terminal and the leakage point, is calculated. L The process of determining the leakage point is based on the leakage voltage V. L Relative to the reference potential difference V S The ratio (V) L / VS The location of the leakage current is determined by [the method described]. In this configuration, the amount of power present between the connected first and second terminals is constant. Therefore, the reference potential difference V between the first and second terminals is [defined]. S It is not easily affected by leakage or charging conditions. Therefore, by calculating the leakage voltage V... L The potential difference V with reference S The ratio (V) L / V S This allows for a more accurate determination of the amount of power present between the reference terminal and the leakage point.

[0015] Based on one embodiment of the leakage current detection method disclosed herein, a leakage current detection circuit is used, which includes: a reference potential difference detection unit connected between a first terminal and a second terminal, and detecting the reference potential difference V. S The leakage voltage detection unit is connected to the first terminal and the second terminal respectively, and is connected to the ground wire at the midpoint. It detects the first ground voltage V, which is equivalent to the potential difference between the first terminal via the ground wire and the leakage point. g( t 1) And the second grounding voltage V, which is equivalent to the potential difference between the second terminal of the ground wire and the leakage point. g( t 2) By using the leakage current detection circuit with the above structure, the first ground voltage V can be accurately detected. g( t 1) Second grounding voltage V g( t 2) and reference potential difference V S As a result, it is possible to calculate the leakage voltage V based on accurate detection results. L .

[0016] Based on one embodiment of the leakage current detection method disclosed herein, the leakage current voltage detection unit includes: a first switch connected to a first terminal side; a first voltage detection resistor disposed between the first switch and a midpoint; a second switch connected to a second terminal side; and a second voltage detection resistor disposed between the second switch and the midpoint. According to this structure, the leakage current voltage detection unit can more accurately detect the first ground voltage V. g( t 1) Second grounding voltage V g( t 2) .

[0017] Based on one form of the leakage current detection method disclosed here, the power supply unit includes: a main positive terminal, which is an open positive terminal capable of being connected to an external device; and a main negative terminal, which is an open negative terminal capable of being connected to an external device. A first terminal is connected to the main positive terminal, and a second terminal is connected to the main negative terminal. The total voltage V of the power supply unit, which is the potential difference between the main positive terminal and the main negative terminal, is used as the basis for this. t As the reference potential difference V S Therefore, it is easier to pinpoint the location of the leakage.

[0018] Based on one form of the leakage current detection method disclosed here, the leakage current voltage measurement step includes: a first measurement step in which a leakage current voltage detection unit, which changes the state of the first switch to on and the second switch to off, measures the first grounding voltage V. g( t 1) The first total voltage V is measured by the reference potential difference detection unit. t( t 1) The second measurement step involves a leakage voltage detection unit that changes the state of the first switch to open and the second switch to open to detect the second grounding voltage V. g ( t 2) The second total voltage V is measured by the reference potential difference detection unit. t( t 2) ; and the leakage voltage calculation process, based on the first grounding voltage V g( t 1) First total voltage V t( t 1) Second grounding voltage V g( t 2) and the second total voltage V t( t 2) To calculate the leakage voltage V L Therefore, a more accurate leakage voltage V can be obtained. L .

[0019] Based on one form of the leakage current detection method disclosed here, the leakage current voltage V is calculated using the main negative terminal as the reference terminal based on the following equations (1) and (2). L The first ground voltage V is synthesized as follows: g( t 1) Second grounding voltage V g( t 2) To calculate the leakage voltage V L It can accurately detect leakage voltage V regardless of changes in the total voltage accompanying charging and discharging. L .

[0020] [Formula 1]

[0021] V L (t)=kV t (t) (1)

[0022] [Formula 2]

[0023]

[0024] Based on one form of the leakage current detection method disclosed herein, the leakage current voltage V is calculated using the main positive terminal as the reference terminal based on the following equations (1)' and (2). L When the positive terminal is used as the reference terminal, by using the following formulas (1)' and (2), the leakage voltage V can be accurately detected without being affected by changes in the total voltage accompanying charging and discharging. L .

[0025] [Formula 3]

[0026] V L (t)=(1-k)V t (t) (1)'

[0027] [Formula 4]

[0028]

[0029] Based on one embodiment of the leakage current detection method disclosed herein, the power supply unit includes multiple connecting parts that electrically connect two adjacent power supplies. A first terminal is connected to one of these connecting parts, and a second terminal is connected to a connecting part different from the one connected to the first terminal. Even in a configuration that does not utilize a total positive terminal and a total negative terminal as in this embodiment, the first ground voltage V can still be detected. g(t1) Second grounding voltage V g(t2) and reference potential difference V S Furthermore, the leakage voltage V can be appropriately calculated based on these detection results. L .

[0030] Based on one form of the leakage current detection method disclosed here, the leakage current voltage V when the second terminal is used as the reference terminal is calculated based on the following equations (3) and (4). L In configurations where the main positive and main negative terminals are not used, the accurate leakage voltage V can be calculated based on the following formula. L .

[0031] [Formula 5]

[0032] V L (t)=kVs(t) (3)

[0033] [Formula 6]

[0034]

[0035] Furthermore, as another aspect of the technology disclosed herein, a leakage current detection circuit is provided for detecting leakage points in a power supply unit electrically connected to multiple power sources. The leakage current detection circuit disclosed herein includes: a reference terminal connected to a predetermined position in the power supply unit; and a leakage voltage detection unit that calculates a leakage voltage V, which is the potential difference between the reference terminal and the leakage point. L ; and the leakage location determination part, based on the leakage voltage V L To determine the location of the leakage current, the leakage detection circuit of this structure detects the potential difference (leakage voltage V) between the reference terminal and the leakage location. L By using this method, the location of the leakage current can be determined. As a result, it is not necessary to install leakage detection circuits at all multiple power sources. Therefore, based on the leakage detection circuit disclosed herein, the location of the leakage current can be determined in detail at low cost and with ease. Attached Figure Description

[0036] Figure 1 This is a perspective view schematically illustrating an example of the structure of a battery pack.

[0037] Figure 2 It is a schematic representation Figure 1 A 3D diagram of a single cell in the image.

[0038] Figure 3 This is a circuit diagram showing a leakage current detection circuit used to implement the leakage current detection method according to the first and second embodiments.

[0039] Figure 4 This is a circuit diagram showing a leakage current detection circuit used to implement the leakage current detection method according to the third embodiment.

[0040] Figure 5 This is a circuit diagram showing a leakage current detection circuit used to implement the leakage current detection method according to the fourth embodiment.

[0041] Figure 6 Yes Figure 5 The diagram illustrates the conductive path of the leakage current detection circuit at the first moment.

[0042] Figure 7 Yes Figure 5 The schematic diagram illustrates the conductive path of the leakage current detection circuit at the second moment.

[0043] Explanation of reference numerals in the attached figures

[0044] 1… Battery pack; 10A~10N… Single cell; 12… Battery box; 13a, 13b… Constraint plates; 13c… Bridging component; 14… Positive terminal; 14a… Total positive terminal; 15… Connecting component; 16… Negative terminal; 16a… Total negative terminal; 17… Buffer plate; 20… Leakage voltage detection unit; 30… Leakage detection resistor; 31… Midpoint; 32… First switch; 33… Second switch; 34… First voltage detection resistor; 35… Second voltage detection resistor; 36… First voltage divider resistor; 37… Second voltage divider resistor; 40… Voltage detection unit; 42… Differential operation circuit; 50… Reference potential difference detection unit; 100… Leakage detection circuit. Detailed Implementation

[0045] The following describes implementations of the technology disclosed herein. Furthermore, matters not specifically mentioned in this specification and necessary for implementing the technology disclosed herein (e.g., detailed construction of the power supply unit, components for constructing the leakage current detection circuit, etc.) can be understood as design matters for those skilled in the art based on prior art. The technology disclosed herein can be implemented based on the content disclosed in this specification and common technical knowledge in the field. Furthermore, the expression "A to B" indicating a range in this specification includes the meaning of A or more and B or less, and includes the meanings of "preferably greater than A" and "preferably less than B".

[0046] <First Implementation>

[0047] The first embodiment of the leakage current detection method disclosed herein will be described below.

[0048] 1. Power Supply Unit

[0049] The leakage current detection method disclosed herein detects leakage points in a power supply unit formed by electrically connecting multiple power sources. In this specification, "power source" refers to a device capable of supplying (discharging) power to an external source. Examples of such power sources include secondary batteries such as lithium-ion batteries, nickel-metal hydride batteries, and nickel-cadmium batteries; primary batteries such as manganese dry batteries and alkaline dry batteries; capacitors such as double-layer capacitors; and power generation components such as fuel cells and solar cells. Furthermore, in this specification, a unit formed by connecting these multiple power sources is referred to as a "power supply unit." An example of such a power supply unit is a battery pack formed by electrically connecting multiple secondary batteries. Additionally, in this specification, each secondary battery constituting a battery pack is referred to as a "single cell."

[0050] The following describes an implementation method that uses battery packs as the inspection target. However, the following description is not intended to limit the inspection target of the leakage current detection method disclosed herein to battery packs. Figure 1 A perspective view schematically illustrating an example of the structure of a battery pack. Figure 2 It is a schematic representation Figure 1 The figures show a three-dimensional view of a single cell. Furthermore, in these figures, reference numeral X indicates the width direction (of the single cell), reference numeral Y indicates the arrangement direction (of the single cell), and reference numeral Z indicates the height direction (of the single cell). Additionally, in the arrangement direction Y, U indicates the upstream side, and D indicates the downstream side. These directions are provided for ease of explanation and are not intended to limit the technology disclosed herein.

[0051] Figure 1 The battery pack (power unit) 1 shown includes multiple (N) individual batteries (power sources) of 10A to 10N. Each individual battery 10A to 10N has a battery case 12 that serves as a flat, square container (see reference). Figure 2 The battery case 12 is formed of a metal material with a specified rigidity, such as aluminum. Although not shown in the diagram, the battery case 12 houses the electrodes and electrolyte, which serve as the site for the charging and discharging reactions. A positive terminal 14 and a negative terminal 16 are mounted on the upper surface 12a of the battery case 12. Although not shown in the diagram, the positive terminal 14 is electrically connected to the positive electrode of the electrodes inside the battery case 12. The upper end of the positive terminal 14 protrudes from the outside of the battery case 12. On the other hand, the negative terminal 16 is electrically connected to the negative electrode of the electrodes inside the battery case 12. The upper end of the negative terminal 16 protrudes from the outside of the battery case 12. Furthermore, the single cell is not limited to a square battery with the above-described structure. That is, the single cell can be a cylindrical battery with a cylindrical battery case, or a laminated battery in which electrodes are sealed within a resin laminate.

[0052] like Figure 1 As shown, in this battery pack 1, multiple individual cells 10A to 10N are arranged adjacent to each other along a predetermined arrangement direction Y. Specifically, each individual cell 10A to 10N is positioned along the long side 12b of the battery box 12 (refer to...). Figure 2 The cells are arranged opposite each other. Furthermore, these individual cells 10A to 10N are constrained along the arrangement direction Y. Specifically, in this group of cells 1, a constraint plate 13a is disposed at the upstream end U in the arrangement direction X. On the other hand, a constraint plate 13b is disposed at the downstream end D. Moreover, the pair of constraint plates 13a and 13b are bridged by a bridging member 13c. Therefore, the individual cells 10A to 10N disposed between the constraint plates 13a and 13b are constrained along the arrangement direction Y with a predetermined constraint pressure. Furthermore, in Figure 1 In the battery pack 1 shown, a buffer plate 17 is inserted between adjacent individual cells. This allows the long side 12b of the battery compartment 12 (see reference 12b) to be exposed. Figure 2The applied constraint pressure becomes uniform. Furthermore, the construction related to the constraint of a single cell is not limited to the techniques disclosed herein and can be appropriately modified according to the construction of the battery pack.

[0053] in addition, Figure 1 The battery pack 1 shown includes multiple connecting members 15 that electrically connect two adjacent individual cells. Specifically, the individual cells 10A to 10N are arranged with their orientations alternating, such that the positive terminal 14 and negative terminal 16 are close to each other between two adjacent individual cells. Furthermore, the positive terminal 14 of one individual cell is electrically connected to the negative terminal 16 of another individual cell via the connecting members 15. Thus, the individual cells 10A to 10N constituting the battery pack 1 can be connected in series. Here, the positive terminal 14 of the nth individual cell 10N, located at the downstream end D in the arrangement direction Y, is not connected to the adjacent individual cell 10N-1. This positive terminal 14 of the nth individual cell 10N becomes an open general positive terminal 14a that can be connected to an external device (vehicle, etc.). Similarly, the negative terminal 16 of the first individual cell 10A, located at the upstream end U in the arrangement direction Y, is not connected to the adjacent individual cell 10B. The negative terminal 16 of the first single cell 10A becomes an open total negative terminal 16a that can be connected to external devices.

[0054] Furthermore, the number of individual cells constituting the battery pack is not particularly limited and can be appropriately varied depending on the required performance of the battery pack (output voltage, installation space, etc.). Although details will be described later, according to the technology disclosed herein, even in battery packs (power supply units) with a large number of individual cells (power sources), the accurate leakage point can be easily determined. Therefore, the technology disclosed herein is particularly suitable for determining the leakage point of battery packs with multiple individual cells. For example, the technology disclosed herein can be applied to battery packs with 50 or more (more preferably 75 or more, further preferably 90 or more, and particularly preferably 100 or more) individual cells. In this way, even in the case of a large number of individual cells, the accurate leakage point can be determined without setting up a complex leakage detection circuit. On the other hand, the upper limit of the number of individual cells constituting the battery pack is not particularly limited and can be 200 or less, or 150 or less.

[0055] 2. Structure of the leakage current detection circuit

[0056] Next, the leakage current detection circuit used to implement the leakage current detection method according to the first embodiment will be described. Figure 3 This is a circuit diagram illustrating a leakage current detection circuit for implementing the leakage current detection methods according to the first and second embodiments. Furthermore, for ease of explanation, in... Figure 3The example illustrates a state where leakage occurs in the third single cell 10C (the third single cell 10C is connected to ground). Furthermore, although details will be described later, the leakage detection method disclosed herein requires connecting a reference terminal at a specified location on the power supply unit. In this embodiment, the first terminal T1 is connected to the total positive terminal 14a of the battery pack 1. Additionally, the second terminal T2 is connected to the total negative terminal 16a. Moreover, in this embodiment, the second terminal T2 is selected as the reference terminal.

[0057] Figure 3 The leakage current detection circuit 100 shown includes a leakage current voltage detection unit 20 and a reference potential difference detection unit 50. Each of them will be described below.

[0058] (1) Leakage voltage detection unit

[0059] The leakage voltage detection unit 20 detects the leakage voltage V, which serves as the potential difference between the reference terminal and the leakage point. L .exist Figure 3 In the illustrated configuration, the second terminal T2, connected to the main negative terminal 16a, is used as the reference terminal. In this case, the potential difference between the main negative terminal 16a and the third single cell 10C becomes the leakage voltage V. L Detect the leakage voltage V. L The leakage voltage detection unit 20 includes a leakage detection resistor 30 and a voltage detection unit 40.

[0060] The leakage current detection resistor 30 is connected to the first terminal T1 and the second terminal T2, respectively. Furthermore, the leakage current detection resistor 30 is connected to the ground wire at its midpoint 31. That is, when leakage occurs in the battery pack 1, the midpoint 31 of the leakage current detection resistor 30 is connected to the leakage point via the ground wire. Moreover, the leakage voltage detection unit 20 is configured to detect the first ground voltage V. g( t 1) Second grounding voltage V g( t 2) The first grounding voltage V here g( t 1) It is the potential difference between the first terminal T1 (general positive terminal 14a) of the ground wire and the leakage point. Additionally, the second grounding voltage V... g( t 2) It is the potential difference between the second terminal T2 (total negative terminal 16a) of the ground wire and the leakage point. The leakage detection resistor 30 of the leakage voltage detection unit 20 is provided with two switching elements consisting of a first switch 32 and a second switch 33, and four resistors consisting of a first voltage detection resistor 34, a second voltage detection resistor 35, a first voltage divider resistor 36, and a second voltage divider resistor 37.

[0061] The first switch 32 is a switching element connected at a position closer to the first terminal T1 than the midpoint 31. On the other hand, the second switch 33 is a switching element connected at a position closer to the second terminal T2 than the midpoint 31. The construction of these switching elements is not particularly limited; semiconductor switching elements such as transistors and FETs, or mechanical switches such as relays, can be used. Although not shown in the figures, the first switch 32 and the second switch 33 are connected to a control unit that controls the operation of the leakage current detection circuit 100. Furthermore, the first switch 32 and the second switch 33 are configured to switch on and off based on signals from the control unit. Although details will be described later, the control unit of the leakage current detection circuit 100 controls the operation of each switching element so that when the first switch 32 is turned on, the second switch 33 is turned off, and when the second switch 33 is turned on, the first switch 32 is turned off.

[0062] Next, the four resistors disposed in the leakage current detection resistor 30 will be described. The first voltage detection resistor 34 is disposed between the first switch 32 and the intermediate point 31. The second voltage detection resistor 35 is disposed between the second switch 33 and the intermediate point 31. Furthermore, the first voltage divider resistor 36 is disposed between the first terminal T1 (total positive terminal 14a) and the first switch 32. And the second voltage divider resistor 37 is disposed between the second terminal T2 (total negative terminal 16a) and the second switch 33. In addition, in Figure 3 In the leakage current detection circuit 100 shown, the first voltage detection resistor 34 and the second voltage detection resistor 35 are set to the same resistance Ra. Additionally, the first voltage divider resistor 36 and the second voltage divider resistor 37 are set to the same resistance Rb. However, the aforementioned resistors can also be different resistors.

[0063] Next, the voltage detection unit 40 is connected to the leakage current detection resistor 30 via the differential operation circuit 42. Specifically, the voltage detection unit 40 is connected to the leakage current detection resistor 30 at a first connection point 38 between the first switch 32 and the first voltage detection resistor 34, and at a second connection point 39 between the second switch 33 and the second voltage detection resistor 35. Furthermore, the voltage detection unit 40 detects the first ground voltage V based on the voltage input from the leakage current detection resistor 30. g( t 1) Second grounding voltage V g( t 2) Although details will be described later, by switching the first switch 32 and the second switch 33 of the leakage detection resistor 30 on and off, the first ground voltage V, which is the potential difference between the first terminal T1 (total positive terminal 14a) of the ground wire and the leakage point, is detected. g( t 1)The second grounding voltage V, which is the potential difference between the second terminal T2 (total negative terminal 16a) of the ground wire and the leakage point. g( t 2) Furthermore, it is possible to utilize this first grounding voltage V g( t 1) Second grounding voltage V g( t 2) To calculate the leakage voltage V L .

[0064] In addition, Figure 3 In the circuit shown, the aforementioned first grounding voltage V g( t 1) The voltage is input to the voltage detection unit 40 under the condition of voltage division by the first voltage divider resistor 36 and the first voltage detection resistor 34. Similarly, the second ground voltage V is input. g( t 2) The voltage is input to the voltage detection unit 40 via the differential operation circuit 42 when the voltage is divided by the second voltage divider resistor 37 and the second voltage detection resistor 35. By setting the voltage divider resistor in this way, the voltage input to the voltage detection unit 40 can be adjusted. Specifically, by making the resistance of the voltage divider resistor greater than the resistance of the voltage detection resistor, the input voltage to the voltage detection unit 40 can be reduced. As a result, the input voltage to the components constituting the voltage detection unit 40 (such as a power amplifier) ​​is reduced to a few volts, avoiding the direct input of a high voltage of hundreds of volts from the battery pack 1. Consequently, the structural components of the voltage detection unit 40 can use general signal processing components, thus further reducing the cost required for detecting leakage current.

[0065] (2) Reference Potential Difference Detection Unit

[0066] Although details will be described later, the leakage current detection method involved in this embodiment is based on the leakage current voltage V. L Relative to the reference potential difference V S The ratio (V) L / V S This is used to determine the location of the leakage. Therefore, in Figure 3 The leakage current detection circuit 100 shown is equipped with a detection reference potential difference V. S The reference potential difference detection unit 50 is connected between the first terminal T1 and the second terminal T2 and detects the reference potential difference V. S The circuit. For example... Figure 3 As shown, in the first embodiment, the reference potential difference detection unit 50 is connected between the first terminal T1, which is connected to the general positive terminal 14a, and the second terminal T2, which is connected to the general negative terminal 16a. Therefore, the reference potential difference V detected by the reference potential difference detection unit 50 is... SThe total voltage V of battery pack 1 is the sum of the voltages of each individual cell from 10A to 10N. t Furthermore, the specific structure of the reference potential difference detection unit 50 is not particularly limited, and conventionally known voltage detection units can be used without particular restriction. Also, the reference potential difference detection unit 50 is connected to the control unit (not shown) in the same manner as the leakage voltage detection unit 20, preferably controlling the measurement of the total voltage V. t (reference potential difference V) S The timing of ( ).

[0067] (3) Determining the location of leakage current

[0068] Furthermore, the leakage current detection circuit 100 according to this embodiment includes the ability to perform leakage current detection based on leakage current voltage V. L The leakage location determination unit is used to determine the leakage location. Furthermore, although not shown in the figure, the leakage location determination unit is connected to the voltage detection unit 40 and the reference potential difference detection unit 50 described above, and is configured to perform the leakage detection method described below based on information (typically voltage) transmitted from these units.

[0069] 3. Leakage current detection method

[0070] The following is a reference. Figure 3 The leakage current detection circuit 100 shown herein will be used to illustrate an example of the leakage current detection method disclosed herein. Specifically, the leakage current detection method disclosed herein is based on the leakage current voltage V. L The location of the leakage current is determined. The leakage current detection method described in the first embodiment aims to more accurately detect leakage current based on the leakage voltage V. L Determine the leakage point and calculate the leakage voltage V. L Relative to the reference potential difference V S The ratio (V) L / V S ), and based on that ratio (V) L / V S The leakage detection method of this first embodiment includes a reference potential difference acquisition step, a leakage voltage measurement step, and a leakage location determination step. Each step will be described below.

[0071] (1) Process of obtaining reference potential difference

[0072] The leakage current detection method according to the first embodiment includes obtaining a reference potential difference V, which serves as the potential difference between the first terminal and the second terminal T2. S The process of obtaining the reference potential difference. As described above, in this embodiment, the first terminal T1 is connected to the total positive terminal 14a of the battery pack 1, and the second terminal T2 is connected to the total negative terminal 16a. Therefore, the reference potential difference V measured by the reference potential difference detection unit 50 is...S The total voltage V of battery pack 1 t Furthermore, in the leakage current detection method according to this embodiment, the first total voltage V measured at different times t1 and t2 in the leakage current voltage measurement process described later is used. t( t 1) Second total voltage V t( t 2) When using battery group 1, which has a relatively small variation in total voltage, as the measurement object, the first total voltage V can also be used. t( t 1) With the second total voltage V t( t 2) Either of them is considered as the "reference potential difference V". S Additionally, the first total voltage V can be... t( t 1) With the second total voltage V t( t 2) The average value is considered as the "reference potential difference V". S ", can also be different from the first total voltage V t( t 1) With the second total voltage V t( t 2) The total voltage detected at the right moment is considered as the "reference potential difference V". S Furthermore, although details will be described later, the reference potential difference V... S The potential difference between the first terminal T1 and the second terminal T2 can be arbitrarily set, and is not limited to the total voltage V of the battery pack. t .

[0073] (2) Leakage voltage measurement procedure

[0074] In the leakage voltage measurement process, the leakage voltage V is calculated as the potential difference between the reference terminal connected to a specified position of the power supply unit and the leakage point. L When the first terminal and the second terminal T2 are connected to the power supply unit (battery pack 1) as in this embodiment, either the first terminal T1 or the second terminal T2 is preferably selected as the reference terminal. For convenience, the following explanation will use the case where the second terminal T2, which is connected to the main negative terminal 16a, is used as the reference terminal.

[0075] In this leakage voltage measurement process, the leakage voltage is measured from the leakage point through the leakage resistance R. L The generated voltage is used to calculate the leakage voltage V based on the measured voltage. L For example, in Figure 3 In the leakage current detection circuit 100 shown, the grounding voltage measured by the leakage current voltage detection unit 20 and the reference potential difference V measured by the reference potential difference detection unit 50 are used as the basis for the detection.S (Total voltage of the battery pack V) t To calculate the leakage voltage V L The following describes the specific procedures for measuring leakage voltage.

[0076] In this leakage voltage measurement process, initially, a first measurement process is performed at the first moment t1 when the first switch 32 is turned on and the second switch 33 is turned off, measuring the voltage input to the voltage detection unit 40. At this time, if there is a leakage point in the battery pack 1, the leakage point (the third single cell 10C) and the first terminal T1 are connected via the ground wire and the leakage resistor R. L The circuit is turned on, and the first ground voltage V is measured by the voltage detection unit 40. g( t 1) Furthermore, in the first measurement step of this embodiment, after measuring the first grounding voltage V... g( t 1) At the appropriate time, the reference potential difference detection unit 50 measures the first total voltage V. t( t 1) .

[0077] In this process, the next step is to measure the voltage input to the voltage detection unit 40 at the second time t2 when the first switch 32 is turned off and the second switch 33 is turned on. At this time, if there is a leakage point in the battery pack 1, the leakage point (the third single cell 10C) and the second terminal T2 are connected via the ground wire and the leakage resistor R. L The circuit is turned on, and the second ground voltage V is measured by the voltage detection unit 40. g( t 2) Furthermore, in the second measurement step of this embodiment, after measuring the second grounding voltage V... g( t 2) At the appropriate time, the reference potential difference detection unit 50 measures the second total voltage V. t( t 2) .

[0078] Furthermore, in the leakage voltage measurement process of this embodiment, the measurement is performed based on the first grounding voltage V. g( t 1) First total voltage V t( t 1) Second grounding voltage V g( t 2) and the second total voltage V t( t 2) To calculate the leakage voltage V L The process of calculating leakage voltage.

[0079] In this leakage voltage calculation process, the leakage resistance R can initially be calculated based on the following equation (5). LFurthermore, in the formula, "Ra" is the resistance of the first voltage sensing resistor 34 and the second voltage sensing resistor 35, and "Rb" is the resistance of the first voltage divider resistor 36 and the second voltage divider resistor 37.

[0080] [Formula 7]

[0081]

[0082] Next, in this process, the leakage voltage V is calculated based on the following equations (1) and (2). L As mentioned above, the leakage voltage V L This is the potential difference between the reference terminal (the second terminal T2 connected to the main negative terminal 16a) and the leakage point. On the other hand, the reference potential difference V in this embodiment... S Total voltage V t This is the potential difference between the positive terminal 14a and the negative terminal 16a. Therefore, the leakage voltage V L With total voltage V t The relationship can be expressed as shown in equation (1) below. Furthermore, in equation (1) below, "k" represents the leakage voltage V. L Relative to the total voltage V t The ratio (V) L / V t ), which is a value in the range of 0 to 1.

[0083] [Formula 8]

[0084] V L (t)=kV t (t) (1)

[0085] Furthermore, the "k" in equation (1) above can be calculated using the following equation (2). In this embodiment, the first ground voltage V, based on the first terminal T1, is measured at different times. t( t 1) and the second ground voltage V based on the second terminal T2 t( t 2) These grounding voltages are synthesized using equation (2). This reduces the impact of charging / discharging, leakage current, and other factors on the total voltage V. t Leakage voltage V L The influence of changes in voltage can be investigated, thus enabling accurate calculation of the leakage voltage V. L Relative to the total voltage V t The ratio (k = V) L / V t ).

[0086] [Formula 9]

[0087]

[0088] (3) Procedure for determining leakage points

[0089] In this process, based on the leakage voltage V L To determine the location of the leakage current. Furthermore, in the leakage current location determination process of this embodiment, the leakage voltage V is calculated. L Relative to the reference potential difference V S The ratio (V) L / V S ), and based on that ratio (V) L / V S This is used to determine the leakage point. For example, in this embodiment, the total voltage V of the battery pack is used. t As the reference potential difference V S Therefore, the leakage voltage V can be calculated using the above formula (2). L Relative to the total voltage V t The ratio k (=V) L / V t It can be based on the leakage voltage V. L Relative to the total voltage V t The ratio k easily and accurately determines the potential from the reference terminal to the leakage point. For example, in a battery pack consisting of 96 3.7V batteries connected in series (total voltage V... t In approximately 355V, the leakage voltage V when the main negative terminal is used as the reference terminal. L At 100V, V L / V S It is 0.28. In this case, it becomes 96 × (V) L / V S = 27.04. Based on this calculation result, it can be determined that leakage occurred in the vicinity of the 27th single cell as observed from the total negative terminal connected to the reference terminal (second terminal T2) (e.g., single cell body, connecting parts, etc.).

[0090] As described above, in the leakage current detection method according to this embodiment, based on the leakage current voltage V... L The leakage point is determined by inferring the number of individual cells present between the reference terminal and the leakage point. Furthermore, the leakage detection method in this embodiment only measures the first ground voltage V. t( t 1) Second grounding voltage V t( t 2) The leakage point can be identified, thus eliminating the need to install leakage detection circuits for all individual cells ranging from 10A to 10N. As described above, the leakage detection method according to this embodiment enables detailed identification of the leakage point at low cost and with ease.

[0091] Furthermore, in the first embodiment, based on the leakage voltage V L Relative to the reference potential difference V S The ratio (V) L / V S To determine the location of the leakage current, the reference potential difference V is present. S The number of 10A to 10N power supplies used in the detection between the first terminal T1 and the second terminal T2 is constant. Therefore, the reference potential difference V S It is less affected by leakage points and can accurately reflect the charging and discharging status of power supply unit 1. Therefore, by calculating the leakage voltage V... L Relative to the reference potential difference V S The ratio (V) L / V S This allows for a more accurate determination of the amount of power present between the reference terminal and the leakage point.

[0092] <Second Implementation>

[0093] The first embodiment of the leakage current detection method disclosed herein has been described above. Furthermore, the above embodiment is not intended to limit the leakage current detection method disclosed herein, and various modifications are possible.

[0094] For example, in the first embodiment described above, the second terminal T2, which is connected to the main negative terminal 16a, is used as the reference terminal. However, the reference terminal can be either the first terminal or the second terminal without particular limitation. That is, in Figure 3 In the circuit shown, even when the first terminal T1 connected to the main positive terminal 14a is used as the reference terminal, it is possible to perform operation based on the leakage voltage V. L Potential difference V from the reference S The ratio (V) L / V S The location of leakage current is determined. In the first embodiment, equations (1) and (2) are calculation formulas when the second terminal T2, connected to the main negative terminal 16a, is used as the reference terminal. When the first terminal T1, connected to the main positive terminal 14a, is used as the reference terminal, equations (1)' and (2) below are preferably used, for example. Therefore, the accurate leakage current voltage V can be calculated. L And perform based on leakage voltage V L Potential difference V from the reference S The ratio (V) L / V S Determining the location of leakage current.

[0095] [Formula 10]

[0096] V L(t)=(1-k)V t (t) (1)'

[0097] [Formula 11]

[0098]

[0099] <Third Implementation Method>

[0100] Furthermore, in the embodiments described above, the first terminal is connected to the main positive terminal, and the second terminal is connected to the main negative terminal. However, the first terminal and the second terminal are not particularly limited as long as they are connected to positions with different potentials in the power supply unit. Hereinafter, a method of connecting the first terminal and the second terminal to positions different from the main positive terminal and the main negative terminal will be described. Figure 4 This is a circuit diagram showing a leakage current detection circuit used to implement the leakage current detection method according to the third embodiment. Furthermore, in Figure 4 The example illustrates a case where a battery pack 1, consisting of six individual cells of 10A to 10F, was inspected and a leakage current was observed at the main positive terminal 14a.

[0101] like Figure 4 As shown, in the third embodiment, the first terminal T1 is connected to a connecting member that connects the fourth single cell 10D and the fifth single cell 10E. Additionally, the second terminal T2 is connected to a connecting member that connects the second single cell 10B and the third single cell 10C. That is, in this embodiment, the third single cell 10C and the fourth single cell 10D are positioned between the first terminal T1 and the second terminal T2. In this case, during the reference potential difference acquisition process, the sum of the voltages of the two single cells 10C and 10D is measured as the reference potential difference V. S Furthermore, although the diagram is omitted, a connection is made between the first terminal T1 and the second terminal T2. Figure 3 The reference potential difference detection unit has the same structure as the reference numeral 50 in the attached figure. Therefore, the reference potential difference V can be measured. S (The sum of the voltages of a single cell at 10C and 10D).

[0102] in addition, Figure 4 The leakage voltage detection unit 20 shown is equipped with a first ground voltage V. g( t 1) The first terminal circuit 60 and the detection of the second ground voltage V g( t 2)The second terminal circuit 70 is provided. The first terminal circuit 60 includes a first switch 64, a first voltage detection resistor 62, a first voltage divider resistor 66, and a first voltage detection unit 68. Conversely, the second terminal circuit 70 includes a second switch 72, a first voltage detection resistor 74, a first voltage divider resistor 76, and a second voltage detection unit 78. Furthermore, the first terminal circuit 60 and the second terminal circuit 70 are connected at a connection point 80, which is connected to ground.

[0103] In the leakage voltage measurement process of the third embodiment, initially, at the first moment t1 when the first switch 64 is turned on and the second switch 72 is turned off, the voltage input to the first voltage detection unit 68 is measured. At this time, if there is a leakage point in the battery pack 1, the leakage point (general positive terminal 14a) and the first terminal T1 are connected via the ground wire and the leakage resistor R. L To measure the first ground voltage V by conducting the circuit. g( t 1) Furthermore, in this embodiment, at the first timing t1, the reference potential difference V between the first terminal T1 and the second terminal T2 is measured. S And use it as the first reference potential difference V S( t 1) .

[0104] Next, at the second timing t2 when the first switch 64 is turned off and the second switch 72 is turned on, the voltage input to the second voltage detection unit 78 is measured. At this time, if there is a leakage point in the battery pack 1, the leakage point (general positive terminal 14a) and the second terminal T2 are connected via the ground wire and the leakage resistor R. L To measure the second ground voltage V by conducting the circuit. g( t 2) Furthermore, in this embodiment, the reference potential difference V is measured again at the second time t2. S And use it as the second reference potential difference V S( t 2) .

[0105] Furthermore, in the leakage voltage measurement process of the third embodiment, the leakage voltage V is calculated based on the following equations (3) and (4). L In this embodiment, the second terminal T2, connected between the second single cell 10B and the third single cell 10C, is used as the reference terminal. Therefore, the leakage voltage V L This becomes the potential difference between the second terminal T2 and the leakage point (general positive terminal 14a). At this time, the leakage voltage V L Potential difference V from the reference S The relationship can be expressed as shown in equation (3) below. Furthermore, in equation (3) below, "k" represents the leakage voltage V. LRelative to the reference potential difference V S The ratio (V) L / V S ).

[0106] [Formula 12]

[0107] V L (t)=kVs(t) (3)

[0108] [Formula 13]

[0109]

[0110] Furthermore, the leakage voltage V calculated in this embodiment L Relative to the reference potential difference V S The ratio (k = V) L / V S The value of "k" is within the range of -1 to 2. For example, when leakage occurs at the location of the positive terminal 14a as viewed from the reference terminal (second terminal T2), the aforementioned "k" is a positive value. On the other hand, when leakage occurs at the location of the negative terminal 16a as viewed from the reference terminal, the aforementioned "k" is a negative value. Therefore, in this embodiment, it is also possible to base the value on the leakage voltage V. L Relative to the reference potential difference V S The ratio (k = V) L / V S This determines the potential from the reference terminal to the leakage point.

[0111] <Fourth Implementation>

[0112] Furthermore, the leakage current detection method disclosed here only needs to be based on the leakage current voltage V L To determine the location of the leakage current, it is sufficient; it is not limited to using a specific circuit or calculation method. In other words, even when using... Figure 3 , Figure 4 The leakage current detection circuit shown has different constructions and uses formulas different from those in (1) to (4) above, as long as it can detect the leakage current voltage V. L This also allows for the implementation of the leakage current detection method disclosed here. The following is a reference... Figure 5 The side can detect leakage voltage V L Another example of a leakage current detection circuit will be illustrated. Furthermore, in Figure 5 The example illustrates a case where a battery pack 1 with six individual cells 10A to 10F is inspected, and leakage occurs in the connection between the fourth individual cell 10D and the fifth individual cell 10E.

[0113] First, in the fourth embodiment, the reference potential difference V is also detected. SAnd calculate the leakage voltage V. L Relative to the reference potential difference V S The ratio (V) L / V S Therefore, in the leakage current detection circuit 100B according to the fourth embodiment, the first terminal T1 is connected to the total positive terminal 14a, and the second terminal T2 is connected to the total negative terminal 16a. Furthermore, a reference potential difference detection unit 50 is connected between the first terminal T1 and the second terminal T2. Therefore, in this embodiment, the total voltage V of the battery pack is also detected. t As the reference potential difference V S Furthermore, in this embodiment, the second terminal T2, which is connected to the main negative terminal 16a, is used as the reference terminal.

[0114] The leakage voltage detection unit 20 in the fourth embodiment includes a suspected leakage circuit 90A and a voltage detection circuit 90B. The suspected leakage circuit 90A is a circuit that connects the ground wire to the first terminal T1. A test resistor 91 and a switch 92 are provided in the suspected leakage circuit 90A. The voltage detection circuit 90B is a circuit that connects the ground wire to the second terminal T2 (reference terminal). A voltage detection resistor 93 and a voltage divider resistor 94 are provided in the voltage detection circuit 90B. In addition, a voltage detection unit 95 for detecting the voltage in the voltage detection resistor 93 is also installed in the voltage detection circuit 90B. In the leakage voltage detection unit 20 with the above structure, the suspected leakage circuit 90A, the voltage detection circuit 90B, and the leakage point (the connection member between the fourth single cell 10D and the fifth single cell 10E) are connected via a ground wire.

[0115] The following describes the leakage voltage measurement procedure when the leakage detection circuit 100B with the above structure is used.

[0116] In the leakage voltage measurement process of this embodiment, initially, the switch 92 of the suspected leakage circuit 90A is turned off. Figure 6 The conductive path at the first moment t1 is shown in the diagram. Figure 6 As shown, if leakage occurs in battery pack 1 at the first time t1, the leakage point and the second terminal T2 are connected via the ground wire and the leakage resistor to measure the first ground voltage V. g( t 1) Furthermore, at this first timing t1, the total voltage V of battery pack 1 was also measured. t (reference potential difference V) S ), and take it as the first total voltage V t( t 1) Furthermore, the leakage voltage V at the first moment t1 L (t1) is represented by the following equation (6). In this equation (6), "k" represents the leakage voltage V in the same way as in the first embodiment described above.L Relative to the total voltage V t The ratio (V) L / V t ), which is a value in the range of 0 to 1.

[0117] [Formula 14]

[0118] V L (t1)=kV t (t1) (6)

[0119] In addition, such as Figure 6 As shown, the leakage detection circuit 100B at the first time t1 includes the first to fourth single cells 10A to 10D, and the leakage resistor R. L The closed circuit includes voltage sensing resistor 93 and voltage divider resistor 94. The first ground voltage V at this time... g( t 1) As shown in equation (7) below. Furthermore, in equation (7), Ra is the resistance value of the voltage sensing resistor 93, Rb is the resistance value of the voltage divider resistor 94, and R... L It is the resistance value of the leakage resistance.

[0120] [Formula 15]

[0121]

[0122] In the leakage voltage measurement process of this embodiment, the next step is to turn on the switch 92 of the suspected leakage circuit 90A. Figure 7 The conductive path at the second time t2 is shown in the diagram. Figure 7 As shown, when leakage occurs in battery pack 1, at the second time t2, the leakage point and the second terminal T2 are also connected via the ground wire and the leakage resistor to measure the second ground voltage V. g( t 2) Additionally, at this second time t2, the total voltage V of the battery pack was also measured. t (reference potential difference V) S ), and use it as the second total voltage V t( t 2) Furthermore, the leakage voltage V at the second time t2 is expressed by the following equation (8). L( t 2) .

[0123] [Formula 16]

[0124] V L (t2)=kV t (t2) (8)

[0125] Here, at the second time t2 when switch 92 is turned on, the current i1 flowing from the main positive terminal 14a through the test resistor 91 of the suspected leakage circuit 90A and the current i2 flowing from the leakage point flow through the ground wire to the voltage detection resistor 93 of the voltage detection circuit 90B. Therefore, with the aforementioned first ground voltage V g( t 1) The second ground voltage V measured at the second time t2 is calculated in different sequences. g( t 2) The following discussion concerns the second grounding voltage V. g( t 2) The calculation order will be explained.

[0126] First, as shown in equation (9) below, at the second time t2, the current i3 flowing to the voltage sensing resistor 93 becomes the sum of the current i1 passing through the test resistor 91 and the current i2 flowing from the leakage point.

[0127] [Formula 17]

[0128] i3 = i1 + i2 (9)

[0129] Additionally, the resistance value R based on leakage resistance L The total voltage V of the battery pack at the second time t2 is calculated from the current i2 flowing from the leakage point, the resistance value Rt of the test resistor 91, and the current i1 passing through the test resistor 91. t( t 2) With leakage voltage V L( t 2) The difference (V) t( t 2) -V L( t 2) (Refer to formula (10) below).

[0130] [Formula 18]

[0131] V t (t2)-V L (t2)=-R L i2+R t i1 (10)

[0132] Next, based on the resistance value Ra of the voltage sensing resistor 93, the resistance value Rb of the voltage divider resistor 94, the current i3 flowing to the voltage sensing resistor 93, and the resistance value R of the leakage resistor... L The leakage voltage V at the second time t2 is calculated using the current i2 flowing from the leakage point. L( t 2) (Refer to formula (11) below).

[0133] [Formula 19]

[0134] V L (t2)=(R a +R b i3+R L i2 (11)

[0135] Furthermore, the second ground voltage V at the second timing t2 is calculated based on the resistance value Ra of the voltage sensing resistor 93 and the current i3 flowing into the voltage sensing resistor 93. g( t 2) (Refer to formula (12) below).

[0136] [Formula 20]

[0137] R a i3 = -V g (t2) (12)

[0138] Here, if we substitute the "current i3" derived from the simultaneous equations (9) to (11) into "i3" in equation (12), we obtain the following equation (13). The second grounding voltage V can be calculated using this equation (13). g( t 2) The value of .

[0139] [Formula 21]

[0140]

[0141] Next, we will discuss the calculation of the leakage voltage V in this embodiment. L Relative to the reference potential difference V S (total voltage V) t The ratio (V) L / V t The explanation will proceed in the following order. First, let's represent "Ra+Rb" in the above formulas as "R" and "V" as "R" and "V" as "R" and "Rb ... respectively. g( t 1) / V t( t 1) When “V1” is represented, according to the simultaneous equations of the above equations (6) and (7), the ratio k of the first timing t1 is expressed as follows in equation (14): L / V t ).

[0142] [Formula 22]

[0143]

[0144] On the other hand, when "Ra+Rb" in each formula is represented as "R" and "V" is represented as "V", g( t 2) / Vt( t 2) In the case of “V2”, according to the simultaneous equations of the above equations (8) and (13), the ratio k of the second timing t2 is expressed as follows in equation (15): L / V t ).

[0145] [Formula 23]

[0146]

[0147] Furthermore, by combining equations (14) and (15) above, equation (16) is obtained. The leakage resistance R can be calculated based on equation (16). L .

[0148] [Formula 24]

[0149]

[0150] Furthermore, by calculating the leakage resistance R based on the above equation (16) L Substituting the value into equation (14), we obtain the leakage voltage V. L Relative to the reference potential difference V S (total voltage V) t The ratio k (=V) L / V t The real number of ). Moreover, similar to the first to third embodiments described above, as long as the leakage voltage V is determined. L Relative to the reference potential difference V S The ratio (V) L / V S By using a real number, the potential from the reference terminal (second terminal T2) to the leakage point can be easily determined. As described above, even when using... Figure 5 In the case of a leakage current detection circuit 100B with the structure shown, the leakage current voltage V can also be calculated appropriately. L Relative to the reference potential difference V S The ratio V L / V S To accurately pinpoint the location of the leakage.

[0151] <Other Changes>

[0152] In the first to fourth embodiments described above, battery packs are used as examples of power supply units to be inspected. However, the structure of the power supply unit is not limited to the leakage detection method disclosed herein. For example, as described above, the leakage detection method disclosed herein can also be applied to power supply units formed by connecting multiple power generation elements (solar cells, etc.). Furthermore, in the embodiments described above, a power supply unit (battery pack) in which all power sources (single cells) are connected in series is used as the inspection object. However, it is not necessary to connect all the power sources constituting the power supply unit to be inspected in series. For example, the leakage detection method disclosed herein can also be used for a power supply unit having multiple parallel power source groups connected in parallel and each of these parallel power source groups connected in series. In this case, it is easy to determine which parallel power source group has a leakage. As a specific example, the leakage detection method disclosed herein can be applied to the determination of leakage points in power supply units including multiple (preferably 30 or more, more preferably 90 or more) connected in series.

[0153] Furthermore, in the first to fourth embodiments, a reference potential difference V is obtained as the potential difference between the first terminal and the second terminal. S And based on the leakage voltage V L Relative to the reference potential difference V S The ratio (V) L / V S This method can be used to determine the location of the leakage current. However, the leakage current detection method disclosed here only needs to be based on the leakage current voltage V. L To pinpoint the location of the leakage current, the method is limited to using a reference potential difference V. S In this way. Specifically, due to the leakage voltage V L It is the potential difference between the reference terminal and the leakage point, therefore even without calculating the potential difference V relative to the reference terminal... S The ratio (V) L / V S This also allows for the determination of the number of power sources existing between the reference terminal and the leakage point to a certain extent. For example, the voltage of the power source can be calculated based on the state of charge (SOC) at which leakage occurs in the power supply unit, and then converted into the number of power sources existing between the reference terminal and the leakage point. Alternatively, when high-precision location determination is not required, the rated voltage of the power supply unit and the leakage voltage V can be used as a reference. L The ratio is used to determine the location of the leakage.

[0154] The above examples illustrate the specific embodiments of the technology disclosed herein, but these are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations to the embodiments described above.

Claims

1. A leakage current detection method, which is a method for detecting leakage current in a power supply unit electrically connected to multiple power sources, wherein, The leakage current detection method comprises: The leakage voltage measurement process involves measuring the voltage generated from the leakage point and calculating the leakage voltage V based on the measured voltage, which serves as the potential difference between a reference terminal connected to a predetermined position in the power supply unit and the leakage point. L ; The process of determining the leakage point is based on the leakage voltage V. L To determine the location of the leakage current; as well as The reference potential difference acquisition process obtains a reference potential difference V between a first terminal connected to a predetermined position in the power supply unit and a second terminal connected to a position with a potential different from that of the first terminal. S , The leakage voltage measurement process selects either the first terminal or the second terminal as the reference terminal, and calculates the leakage voltage V, which is the potential difference between the reference terminal and the leakage point. L , The process for determining the leakage point is based on the leakage voltage V. L Relative to the reference potential difference V S The ratio (V) L / V S To determine the location of the leakage current.

2. The leakage current detection method according to claim 1, wherein, Use a leakage current detection circuit. This leakage current detection circuit has the following features: A reference potential difference detection unit is connected between the first terminal and the second terminal, and detects the reference potential difference V. S ; and The leakage voltage detection unit is connected to the first terminal and the second terminal respectively, and is connected to the ground wire at the midpoint. It detects a first ground voltage V equivalent to the potential difference between the first terminal via the ground wire and the leakage point. g （ t 1） and a second grounding voltage V, which is equivalent to the potential difference between the second terminal of the ground wire and the leakage point. g （ t 2） .

3. The leakage current detection method according to claim 2, wherein, The leakage voltage detection unit includes: A first switch is connected to the first terminal side; A first voltage sensing resistor is disposed between the first switch and the midpoint; The second switch is connected to the second terminal side; as well as A second voltage sensing resistor is positioned between the second switch and the intermediate point.

4. The leakage current detection method according to claim 3, wherein, The power supply unit includes: The main positive terminal is an open positive terminal that can be connected to external devices; and The main negative terminal is an open negative terminal that can be connected to the external device. The first terminal is connected to the total positive terminal, the second terminal is connected to the total negative terminal, and the total voltage V of the power supply unit, which is the potential difference between the total positive terminal and the total negative terminal, is... t As the reference potential difference V S .

5. The leakage current detection method according to claim 4, wherein, The leakage voltage measurement process includes: In the first measurement step, the leakage voltage detection unit, which turns the first switch on and the second switch off, detects the first ground voltage V. g（ t 1） The first total voltage V is measured by the reference potential difference detection unit. t（ t 1） ; In the second measurement step, the leakage voltage detection unit, which changes the state of the first switch to open and the second switch to close, detects the second ground voltage V. g（ t 2） The second total voltage V is measured by the reference potential difference detection unit. t（ t 2） ; as well as The leakage voltage calculation process is based on the first grounding voltage V. g（ t 1） The first total voltage V t（ t 1） The second grounding voltage V g（ t 2） and the second total voltage V t（ t 2） To calculate the leakage voltage V L .

6. The leakage current detection method according to claim 5, wherein, Based on the following equations (1) and (2): To calculate the leakage voltage V when the total negative terminal is used as the reference terminal. L .

7. The leakage current detection method according to claim 5, wherein, Based on the following equations (1) and (2): To calculate the leakage voltage V when the total positive terminal is used as the reference terminal. L .

8. The leakage current detection method according to claim 3, wherein, The power supply unit has multiple connection components that electrically connect two adjacent power supplies. The first terminal is connected to one of the plurality of connecting parts, and the second terminal is connected to a connecting part different from the connecting part to which the first terminal is connected.

9. The leakage current detection method according to claim 8, wherein, Based on the following equations (3) and (4): To calculate the leakage voltage V when the second terminal is used as the reference terminal. L .

10. A leakage current detection circuit for detecting leakage points in a power supply unit electrically connected to multiple power sources, wherein, The leakage current detection circuit includes: The reference terminal is connected to a designated position in the power supply unit; The leakage voltage detection unit measures the voltage generated from the leakage point and calculates the leakage voltage V, which serves as the potential difference between the reference terminal and the leakage point, based on the measured voltage. L ; The leakage location determination unit is based on the leakage voltage V. L To determine the location of the leakage current; as well as The reference potential difference detection unit acquires a reference potential difference V between a first terminal connected at a predetermined position in the power supply unit and a second terminal connected at a different potential from the first terminal. S , The leakage location determination unit selects either the first terminal or the second terminal as the reference terminal, and calculates the leakage voltage V, which is the potential difference between the reference terminal and the leakage location. L , The leakage location determination unit is based on the leakage voltage V. L Relative to the reference potential difference V S The ratio (V) L / V S To determine the location of the leakage current.

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