WO2023176348A1

WO2023176348A1 - Circuit protection device

Info

Publication number: WO2023176348A1
Application number: PCT/JP2023/006494
Authority: WO
Inventors: 友廣三輪; 昌明北川
Original assignee: 株式会社デンソー
Priority date: 2022-03-18
Filing date: 2023-02-22
Publication date: 2023-09-21
Also published as: JP2023137585A

Abstract

A circuit protection device (20) for protecting monitoring circuits (22) that monitor the voltage of a power source unit (1) is provided with: overvoltage protection elements (212) that are connected between a plurality of detection lines (M) connecting between the power source unit and the monitoring circuits and that undergo a short-circuit failure when an overvoltage has been applied; circuit protection elements (211) that are provided to each of the detection lines and cut off the electrical connection between the power source unit and the monitoring circuits when a current at or above a predetermined current value flows on the detection lines; and impedances (25) that are provided to at least one of the detection lines and are arranged at locations that are between the power source unit and the circuit protection elements. In the event of overvoltage, the overvoltage protection elements undergo a short-circuit failure and maintain a short-circuit state between detection lines, the circuit protection elements cut off the electrical connection between the power source unit and the monitoring circuits due to a short-circuit current flowing between the detection lines via the overvoltage protection elements; and the impedances suppress the generation of a discharge current when the short-circuit current causes the circuit protection elements to cut off the electrical connection between the power source unit and the monitoring circuits.

Description

circuit protection device

Cross-reference of related applications

This application is based on Japanese Application No. 2022-043847 filed on March 18, 2022, and the contents thereof are incorporated herein.

It relates to a circuit protection device that protects a monitoring circuit that monitors the voltage of a power supply unit.

For example, a hybrid vehicle or an electric vehicle is equipped with an assembled battery in which a large number of battery cells are connected in series as a power source, and a driving electric motor is driven by the voltage generated by the power source. As in Patent Document 1, this type of power supply section is connected to a monitoring circuit that monitors the voltage in order to prevent heat generation, burnout, deterioration, etc. due to voltage abnormality, and a monitoring circuit is installed between the power supply section and the monitoring circuit. A circuit protection device is provided to protect the circuit.

Here, the power supply section and the monitoring circuit are electrically connected by multiple detection lines for voltage detection, and overvoltage may occur in the power supply section due to the influence of peripheral devices, or large current may flow in the detection line. Otherwise, the monitoring circuit may be destroyed. Therefore, it is necessary to provide a circuit protection device between the power supply section and the monitoring circuit to protect the monitoring circuit.

The circuit protection device of Patent Document 1 includes an overvoltage protection element (for example, a Zener diode), and a circuit protection element (e.g., fuse) that is installed in each of the plurality of detection lines and cuts off the electrical connection between the power supply and the monitoring circuit when a current exceeding a predetermined current value flows through the detection line. Equipped with. When an overvoltage occurs in the power supply, the overvoltage protection element maintains a short circuit between multiple detection lines, and the circuit protection element cuts off the electrical connection between the power supply and the monitoring circuit. The monitoring circuit can be appropriately protected from overvoltages generated in the parts.

Japanese Patent Application Publication No. 2014-7883

In the circuit protection device of Patent Document 1, a discharge current may flow due to arc discharge or the like at a location where the electrical connection between the power supply section and the monitoring circuit is interrupted by a circuit protection element such as a fuse.

In view of the above, an object of the present disclosure is to provide a circuit protection device that can suppress discharge current when a circuit protection element is cut off.

The present disclosure provides a circuit protection device that protects a monitoring circuit that monitors the voltage of a power supply unit. This circuit protection device includes an overvoltage protection element that is connected between a plurality of detection lines for voltage detection that connects the power supply section and the monitoring circuit, and that causes a short-circuit failure when an overvoltage is applied; a circuit protection element that is provided in each of the detection lines and interrupts electrical connection between the power supply section and the monitoring circuit when a current of a predetermined current value or more flows through the detection line; and at least one of the detection lines. and an impedance disposed at a position between the power supply section and the circuit protection element. The overvoltage protection element is configured to cause a short-circuit failure and maintain a short-circuit state between the plurality of detection lines when an overvoltage occurs in the power supply section. The circuit protection element is configured to cut off electrical connection between the power supply unit and the monitoring circuit by a short circuit current flowing between the detection lines via the overvoltage protection element when an overvoltage occurs in the power supply unit. configured to do so. The impedance is configured to suppress generation of discharge current when the circuit protection element interrupts electrical connection between the power supply section and the monitoring circuit due to the short circuit current.

The circuit protection device of the present disclosure includes impedance in at least one of the detection lines. The impedance is arranged at a position between the power supply section and the circuit protection element. Impedance is a concept that includes resistance and reactance (inductive reactance and capacitive reactance), and specific configurations include impedance elements such as resistors, inductors, and capacitors, and wiring that functions as impedance. . When a short-circuit current interrupts the electrical connection between the power supply and the monitoring circuit, the circuit protection element can reduce the electric field (i.e. potential difference) at the point where a discharge may occur due to the voltage drop in the impedance. Therefore, generation of discharge current can be suppressed. Since the possibility of the monitoring circuit being destroyed by the discharge current generated in the broken circuit protection element can be reduced, it is possible to provide the circuit protection unit 20 that can protect the monitoring circuit 22 more reliably than before.

The above objects and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. The drawing is
FIG. 1 is an overall diagram of a power supply system including a circuit protection device according to a first embodiment, FIG. 2 is a diagram showing main parts of a battery monitoring device including a circuit protection device according to the first embodiment, FIG. 3 is a diagram illustrating the functions of the circuit protection device according to the first embodiment, FIG. 4 is a diagram showing main parts of a battery monitoring device including a circuit protection device according to a modification, FIG. 5 is a diagram showing main parts of a battery monitoring device including a circuit protection device according to a second embodiment.

(First embodiment)
In the first embodiment, the circuit protection device of the present disclosure is applied to a power supply system installed in a hybrid vehicle or an electric vehicle. As shown in FIG. 1, the power supply system of this embodiment includes an assembled battery 1 and a battery monitoring device 2 as main components. Note that in each of the following embodiments, parts that are the same or equivalent to each other are given the same reference numerals in the drawings.

The assembled battery 1 mainly supplies power to a traveling electric motor (not shown) and various electric loads mounted on the vehicle, and constitutes a power supply section of the present disclosure. The assembled battery 1 of the present embodiment has a plurality of battery cells 10 made of secondary batteries such as lithium ion batteries connected in series, and includes a plurality of battery blocks B1 grouped into a predetermined number of adjacent battery cells 10. It is configured as a series connection of ~Bn.

The battery monitoring device 2 is a device that monitors the assembled battery 1 by detecting various states such as the voltage of the assembled battery 1, and monitors each battery cell 10 of the assembled battery 1 via a detection line M for voltage detection, etc. Connected to both terminals.

The battery monitoring device 2 of this embodiment includes a circuit protection section 20, a plurality of monitoring circuits 22, a control section 23, and an insulating section 24 as main components.

The circuit protection unit 20 is a circuit protection device that protects the monitoring circuit 22 from the assembled battery 1, and includes a circuit protection element 211, an overvoltage protection element 212, and an impedance element 25. The circuit protection element 211 and the overvoltage protection element 212 are provided on the same circuit board 21, and the impedance element 25 is provided outside the circuit board 21. Note that, as described later, the impedance element 25 may be provided on the circuit board 21.

The circuit protection element 211 is provided in each detection line M, and is an element that interrupts electrical connection between the assembled battery 1 side and the monitoring circuit 22 when a current exceeding a predetermined current value flows through the detection line M. . Further, the overvoltage protection element 212 is an element that is connected between each detection line M and maintains the voltage applied to the monitoring circuit 22 at a constant voltage. The overvoltage protection element 212 is composed of an element that causes a short-circuit failure when an overvoltage is applied.

The impedance element 25 is provided on at least one of the detection lines M, and is arranged at a position between the power supply section and the circuit protection element 211. In this embodiment, each detection line M is provided with an impedance element 25, respectively.

Details of the circuit protection element 211, overvoltage protection element 212, and impedance element 25 in the circuit protection section 20 will be described later.

A plurality of monitoring circuits 22 are provided corresponding to each of the battery blocks B1 to Bn of the assembled battery 1, and are circuits that monitor the block voltages of the battery blocks B1 to Bn and the cell voltages of the battery cells 10 in the assembled battery 1. The monitoring circuit 22 of this embodiment is configured to output a signal indicating the voltage state of the assembled battery 1 and the like to the control section 23 via the insulating section 24.

The control unit 23 is composed of a microcomputer consisting of a CPU, ROM, RAM, EEPROM (registered trademark), etc., and its peripheral equipment, and performs control processing of each monitoring circuit 22 according to a control program stored in a storage means such as a ROM. It is configured to execute various processes such as a process for determining whether the voltage of the assembled battery 1 is abnormal.

The insulating section 24 is a signal transmitting means that transmits signals in both directions while insulating each monitoring circuit 22 and the control section 23, and is composed of, for example, a photocoupler.

Next, details of the circuit protection unit 20 of this embodiment will be explained using the main part configuration diagram shown in FIG. 2. For convenience of explanation, FIG. 2 shows one battery block Bi among the plurality of battery blocks B1 to Bn, the monitoring circuit 22 that monitors the battery block Bi, and the circuit protection unit 20 that protects the monitoring circuit 22. Illustrated.

The overvoltage protection element 212 of this embodiment is an element that prevents overvoltage generated in the battery block Bi from being applied to the monitoring circuit 22, and is an element that prevents overvoltage generated in the battery block Bi from being applied to the monitoring circuit 22. At this time, the detection lines connected to both terminals of the battery cell 10 are maintained in a short-circuited state (conductive state).

In this embodiment, the overvoltage protection element 212 is composed of a Zener diode ZD, and as shown in FIG. 2, the Zener diodes ZD1 to ZDn are connected between each detection line M1 to Mn+1.

The Zener diode ZD of this embodiment has a breakdown voltage (for example, several times the full charge voltage of the battery cell 10) set in consideration of the voltage of the battery cell 10 and the withstand voltage of the monitoring circuit 22. Note that each of the Zener diodes ZD1 to ZDn has a cathode connected to a detection line connected to a high potential terminal of the battery cell 10 among a pair of detection lines connected to both terminals of the battery cell 10, and a low potential The anode is connected to the detection line connected to the side terminal.

Furthermore, this embodiment employs a Zener diode ZD that has a structure that causes a short-circuit failure when an overvoltage is applied. Specifically, for example, the Zener diode ZD includes a PN junction type IC chip, a pair of lead frames that sandwich the IC chip at one end, and a resin exterior part that covers part of the IC chip and the lead frame. may be configured. Note that if the Zener diode ZD has a structure in which the IC chip and the lead frame are bonded with a wire, there is a possibility that the wire will break and an open failure will occur when an overvoltage is applied. For this reason, it is preferable to employ a Zener diode ZD having a structure in which the IC chip is directly sandwiched between a pair of lead frames.

Subsequently, when an overvoltage occurs, the circuit protection element 211 of this embodiment protects both terminals of the battery cell 10 where the overcurrent has occurred and the monitoring circuit 22 due to the short circuit current flowing between the detection line M via the overvoltage protection element 212. It is configured to interrupt electrical connection between. That is, the circuit protection element 211 uses an element that is broken by a short circuit current flowing between the detection lines M via the overvoltage protection element 212 when an overvoltage occurs.

Specifically, in this embodiment, the circuit protection element 211 is configured with a fuse F that ruptures when a current higher than the rated current flows, and as shown in FIG. 2, fuses F1 to Fn+1 are connected to each detection line. Provided at M1 to Mn+1.

The fuse F of this embodiment is configured to be ruptured by a large current flowing through the detection line M when the Zener diode ZD is short-circuited due to overvoltage. In other words, the rated current of the fuse F is set based on the large current flowing through the detection line M when the Zener diode ZD is short-circuited due to overvoltage. Note that if the resistance component of the fuse F is large, it will affect the accuracy of voltage monitoring in the monitoring circuit 22, so it is desirable to select a fuse F with a small resistance value.

The impedance element 25 of this embodiment is provided on at least one of the detection lines M, and is arranged at a position between the assembled battery 1 and the circuit protection element 211. The impedance element 25 is configured such that when an overvoltage occurs, a short circuit current flows between the detection line M via the overvoltage protection element 212, and the circuit protection element 211 is connected between both terminals of the battery cell 10 where the overcurrent has occurred and the monitoring circuit 22. It is configured to suppress generation of discharge current in the circuit protection element 211 when the electrical connection of the circuit protection element 211 is interrupted. For example, the impedance element 25 is configured such that when an overvoltage occurs, a short circuit current flows between the detection line M via the overvoltage protection element 212, and the circuit protection element 211 connects both terminals of the battery cell 10 where the overcurrent has occurred and the monitoring circuit 22. The electrical characteristics such as resistance value and inductance are designed to suppress generation of discharge current in the circuit protection element 211 when the electrical connection between the elements is interrupted.

As shown in FIG. 2, in this embodiment, an inductor L is exemplarily used as the impedance element 25, and inductors L1 to Ln+1 are arranged in all of the detection lines M1 to Mn+1, respectively. Specifically, the inductors L1 to Ln+1 are designed to have inductances that suppress generation of discharge current in the ruptured fuses when the corresponding fuses F1 to Fn+1 are ruptured. The inductances of the inductors L1 to Ln+1 are designed based on an experimental method, for example, by setting them based on inductances that do not allow arc current to flow, which were determined by actually rupturing one of the fuses F1 to Fn+1. be able to.

Next, the action of the circuit protection section 20 when an overvoltage occurs in the assembled battery 1 will be explained. When an overvoltage occurs in the assembled battery 1 and a voltage exceeding the breakdown voltage is applied to the Zener diodes ZD1 to ZDn, a large current (short circuit current) is generated in the closed circuit formed between the assembled battery 1 and the Zener diodes ZD1 to ZDn. flows.

At this time, if the Zener diodes ZD1 to ZDn are short-circuited, a large current (short circuit current) continues to flow through the closed circuit formed between the assembled battery 1 and the Zener diodes ZD1 to ZDn, and the electrical connection is interrupted. According to this, since no overvoltage is applied to the monitoring circuit 22 side, the monitoring circuit 22 is appropriately protected from the overvoltage generated in the assembled battery 1.

For example, if an overvoltage occurs in the battery cell 10 having the second highest potential in the battery block Bi shown in FIG. 2, and a voltage exceeding the breakdown voltage is applied to the Zener diode ZD2, as shown by the arrow in FIG. A large current (short circuit current) flows through a closed circuit formed by the battery cell 10, the detection lines M2 and M3, and the Zener diode ZD2.

At this time, as shown in FIG. 3(a), if the Zener diodes ZD1 to ZDn are short-circuited, a large current (short-circuit current) continues to flow through the closed circuit formed between the battery cell 101 and the Zener diode ZD2. At this time, an electromotive force is generated in the inductor L2 as a counter electromotive force in a direction that prevents the short circuit current. As shown in FIG. 3(b), when a short circuit current flows through fuse F2, as shown in FIG. 3(c), when fuse F2 is ruptured, electrical connection between battery cell 10 and monitoring circuit 22 is established. is blocked. At this time, an electromotive force is generated in the inductor L2 as a back electromotive force in a direction that causes the short circuit current to continue flowing. Furthermore, the potential difference between the blown fuses F2 increases, and the electric field also increases.

In the fuse F2 whose electrical connection is cut off due to rupture, a discharge current may flow due to arc discharge or the like, as shown by the arrow in FIG. 3(d). At this time, an electromotive force that obstructs the discharge current is generated in the inductor L2 as a back electromotive force. The inductor L2 is designed to have an inductance that suppresses generation of discharge current in the fuse F2 when the corresponding fuse F2 is ruptured. Therefore, due to the back electromotive force generated in the inductor L2, the potential difference between the blown fuses F2 can be reduced, the electric field can be reduced, and the generation of discharge current can be suppressed.

As explained above, the circuit protection unit 20 of this embodiment includes the overvoltage protection element 212, the circuit protection element 211, and the impedance element 25. The overvoltage protection element 212 is constituted by an element that causes a short-circuit failure when an overvoltage is applied. When an overvoltage occurs in the assembled battery 1, the overvoltage protection element 212 causes a short-circuit failure and maintains a short-circuit state between each detection line M. The circuit protection element 211 is broken by a short circuit current flowing between each detection line M via the overvoltage protection element 212 when an overvoltage occurs in the assembled battery 1 . As a result, when overvoltage occurs in the assembled battery 1, the overvoltage protection element 212 maintains the short circuit between each detection line M, and the circuit protection element 211 maintains the electrical connection between the assembled battery 1 and the monitoring circuit 22. Since the physical connection is cut off, the monitoring circuit 22 can be appropriately protected from overvoltage generated in the assembled battery 1.

Furthermore, when the circuit protection element 211 interrupts the electrical connection between the assembled battery 1 and the monitoring circuit 22, the voltage drop of the impedance element 25 reduces the potential difference at the broken part of the broken circuit protection element 211. Since the electric field in the space between the broken parts can be reduced, generation of discharge current in the broken circuit protection element 211 can be suppressed. Since the possibility that the monitoring circuit 22 will be destroyed by the discharge current generated in the broken circuit protection element 211 can be reduced, it is possible to provide the circuit protection unit 20 that can protect the monitoring circuit 22 more reliably than before.

Further, the impedance element 25 is an inductor L1 to Ln+1, and has an inductance that suppresses generation of discharge current when the circuit protection element 211 interrupts the electrical connection between the assembled battery 1 and the monitoring circuit 22. can be designed. Furthermore, the inductors L1 to Ln+1 are not provided on the circuit board 21 on which the circuit protection element 211 and the overvoltage protection element 212 are provided, and are provided between the assembled battery 1 and the circuit board 21 outside the circuit board 21. It is set in. Therefore, the circuit protection unit 20 according to this embodiment can be realized by simply adding the inductor L to the circuit board 21 on which the circuit protection element 211 and the overvoltage protection element 212 are provided as in the conventional case.

In this embodiment, since the overvoltage protection element 212 is configured with a Zener diode ZD that causes a short circuit failure when an overvoltage is applied, a short circuit that flows between each detection line M occurs when the Zener diode ZD causes a short circuit failure. Any circuit protection element 211 that interrupts each detection line M with current can be used. Therefore, the number of choices for the circuit protection element 211 increases, and selection of the circuit protection element 211 becomes easy.

(Modified example)
As shown in FIG. 4, the circuit protection element 211, the overvoltage protection element 212, and the inductor L may all be provided on the same circuit board 21. Even if the inductor L is provided on the circuit board 21 as in the circuit protection section 20 shown in FIG. 4, a discharge current will occur in the broken circuit protection element 211 as in the circuit protection section 20 shown in FIG. It is possible to provide the circuit protection unit 20 that can suppress the noise and protect the monitoring circuit 22 more reliably than before. By simply installing the circuit board 21 including the circuit protection element 211, the overvoltage protection element 212, and the inductor L in a power supply system including the monitoring circuit 22 and the power supply unit, a power supply system including the circuit protection device according to the present application can be created. realizable.

Further, the inductor L may be provided at least on the highest detection line M1, which is the highest potential side of the detection lines M, and the lowest detection line Mn+1, which is the lowest potential side. That is, the circuit protection unit 20 only needs to include at least the inductor L1 and the inductor Ln+1 as the inductor L.

For example, in FIG. 1, if the wiring members connecting each of the battery blocks B1 to Bn to each other become disconnected, an overvoltage is generated at the disconnected location, and the fuse provided in the detection line is ruptured. For example, if the connection member connecting battery block B1 and battery block B2 comes off, fuse Fn+1 provided on the lowest detection line Mn+1 of battery block B1 and the fuse provided on the highest detection line M1 of battery block B2 F1 breaks. Then, in the battery block B1, the fuses are ruptured in a chain from the lowest detection line Mn+1 to the highest detection line M1. In the battery block B2, the fuses are ruptured in a chain from the highest detection line M1 to the lowest detection line Mn+1. The overvoltage increases as the chain of fuse ruptures progresses. Eventually, in the battery block B1, the overvoltage generated in the highest detection line M1 becomes the largest, and the fuse F1 ruptures. Therefore, by providing the inductor L1 in the uppermost detection line M1, generation of discharge current can be suppressed. Furthermore, in the battery block B2, the overvoltage generated in the lowest detection line Mn+1 eventually becomes the largest, and the fuse Fn+1 breaks. Therefore, by providing the inductor Ln+1 on the lowest detection line Mn+1, generation of discharge current can be suppressed. When only inductor L1 and inductor Ln+1 are provided, for example, in the power supply system of a hybrid vehicle or an electric vehicle, the voltage charged in the smoothing capacitor connected in parallel to the battery pack 1 and the final By calculating the path current from the path resistance of the current path, the inductance of the inductor L1 and the inductor Ln+1 can be designed.

(Second embodiment)
As shown in the configuration diagram of FIG. 5, in the circuit protection unit 20 according to the second embodiment, the impedance element 25 is configured with a resistor R instead of an inductor L. This is different from the circuit protection unit 20 according to the embodiment. Note that descriptions of parts similar to or equivalent to those in the first embodiment will be omitted or simplified.

As shown in FIG. 5, in this embodiment, a resistor R is exemplarily used as the impedance element 25, and resistors R1 to Rn+1 are arranged in all of the detection lines M1 to Mn+1, respectively. Specifically, the resistors R1 to Rn+1 are designed to have resistance values that suppress generation of discharge current in the ruptured fuses when the corresponding fuses F1 to Fn+1 are ruptured. The resistance values of the resistors R1 to Rn+1 can be designed based on an experimental method, similar to the inductance of the inductors L1 to Ln+1 according to the first embodiment.

Similarly to the first embodiment, for example, when an overvoltage occurs in the battery cell 10 having the second highest potential of the battery block Bi shown in FIG. 5 and a voltage exceeding the breakdown voltage is applied to the Zener diode ZD2, the battery A short circuit current flows through the closed circuit formed by the cell 10, the detection lines M2, M3, and the Zener diode ZD2. When the Zener diodes ZD1 to ZDn are short-circuited and the fuse F2 is ruptured, the electrical connection between the battery cell 10 and the monitoring circuit 22 is cut off. In the fuse F2 where the electrical connection is cut off, a discharge current may flow due to arc discharge or the like. Resistor R2 is designed to have a resistance value that suppresses generation of discharge current in fuse F2. Therefore, the resistor R2 can reduce the potential difference between the blown fuses F2, reduce the electric field, and suppress the generation of discharge current.

Even if the impedance element 25 is configured with a resistor R as in the present embodiment, the effect is that it is possible to suppress the generation of discharge current in the fuse F whose electrical connection is cut off, as in the first embodiment. play. Furthermore, the resistors R1 to Rn+1 are not provided on the circuit board 21 where the circuit protection element 211 and the overvoltage protection element 212 are provided, and are provided between the assembled battery 1 and the circuit board 21 outside the circuit board 21. is provided in between. Therefore, the circuit protection unit 20 according to the present embodiment can be realized by simply adding the resistor R to the circuit board 21 on which the circuit protection element 211 and the overvoltage protection element 212 are provided as in the conventional case.

Note that, similar to the circuit protection unit 20 shown in FIG. 4, the circuit protection element 211, the overvoltage protection element 212, and the resistor R may all be provided on the same circuit board 21. Even in this case, like the circuit protection unit 20 shown in FIG. 4, the circuit protection unit 20 can suppress generation of discharge current in the broken circuit protection element 211, and can protect the monitoring circuit 22 more reliably than before. can be provided. A power supply system equipped with a circuit protection device according to the present application can be obtained by simply installing a circuit board 21 equipped with a circuit protection element 211, an overvoltage protection element 212, and a resistor R in a power supply system equipped with a monitoring circuit 22 and a power supply section. can be realized.

Further, the resistor R may be provided at least on either the highest detection line M1 or the lowest detection line Mn+1. That is, the circuit protection unit 20 only needs to include at least one of the resistor R1 and the resistor Rn+1 as the resistor R.

For example, in FIG. 1, if the wiring member connecting battery block B1 and battery block B2 comes off, as described above, in battery block B1, the overvoltage generated in the highest detection line M1 will eventually become the highest. becomes larger, and the fuse F1 is ruptured. In battery block B2, the overvoltage generated on the lowest detection line Mn+1 becomes the largest, and fuse Fn+1 breaks. Therefore, by providing at least one of the resistor R1 and the resistor Rn+1, the generation of discharge current can be suppressed. When only one of the resistor R1 and the resistor Rn+1 is provided, for example, in the power supply system of a hybrid vehicle or electric vehicle, the voltage charged in the smoothing capacitor connected in parallel to the assembled battery 1 and the fuse are connected in a chain. The resistance value of resistor R1 or resistor Rn+1 can be designed by calculating the path current from the path resistance of the final current path after the current path is broken.

Further, in each of the above embodiments, an example was explained in which the circuit protection element 211 is composed of the fuse F, but the circuit protection element 211 is not limited to the fuse F, and any element that can perform the same function as the fuse F can be used as the circuit protection element 211. It can be adopted as For example, a resistance element that is ruptured by a short circuit current flowing between the detection lines M via the overvoltage protection element 212 when an overvoltage occurs may be used as the circuit protection element 211. Note that the resistance element serving as the circuit protection element 211 is desirably configured with a low resistance element having a low resistance value in order to suppress the influence on the voltage detection performance in the monitoring circuit 22.

In each of the above embodiments, an example in which the overvoltage protection element 212 is formed of a Zener diode ZD has been described. However, the overvoltage protection element 212 is not limited to the Zener diode ZD. 212.

In each of the above embodiments, a circuit protection device using a resistor or an inductor is used as an impedance. However, the present invention is not limited thereto. As the impedance, an impedance element other than a resistor or an inductor (for example, a capacitor) may be used, or a wiring that functions as an impedance or the like may be used. In addition, as for the specific examples of impedance illustrated above, only the same type of impedance may be used, or a plurality of types may be used in combination. For example, the circuit protection device may include both an inductor and a resistor as impedance.

In each of the above embodiments, an example has been described in which the circuit protection device of the present disclosure is applied to the monitoring circuit 22 related to the voltage of the assembled battery 1 mounted on a vehicle, but the circuit protection device is not limited to this, and may be used for other purposes. It can be applied to a monitoring circuit related to the voltage of a power supply section. Note that the power supply section is not limited to a battery, and may be any power source that can supply power to various electrical loads.

According to each of the above embodiments, the following effects can be obtained.

The circuit protection unit 20 functions as a circuit protection device that protects the monitoring circuit 22 that monitors the voltage of the power supply unit (for example, the assembled battery 1). The circuit protection unit 20 is connected between a plurality of detection lines M for voltage detection connecting between the power supply unit and the monitoring circuit 22, and includes an overvoltage protection element 212, a circuit protection element 211, and an impedance element 25. Be prepared. The overvoltage protection element 212 is an element that causes a short-circuit failure when an overvoltage is applied, and is configured to cause a short-circuit failure and maintain a short-circuited state between the plurality of detection lines M when an overvoltage occurs in the power supply section. Ru. The circuit protection element 211 is provided in each of the plurality of detection lines M, and is an element that interrupts electrical connection between the power supply section and the monitoring circuit 22 when a current of a predetermined current value or more flows through the detection line M. When an overvoltage occurs in the power supply section, a short circuit current flows between the detection lines via the overvoltage protection element 212 to interrupt the electrical connection between the power supply section and the monitoring circuit 22.

The impedance element 25 is provided in at least one of the detection lines M, and is arranged at a position between the power supply section and the circuit protection element 211, so that the circuit protection element 211 is connected between the power supply section and the monitoring circuit 22 due to a short circuit current. The structure is configured to suppress the generation of discharge current when the electrical connection is interrupted.

The impedance element 25 is an element that makes it difficult for current to flow, and specific examples include a resistor R and an inductor L. When the circuit protection element 211 interrupts the electrical connection between the power supply section and the monitoring circuit 22 due to a short circuit current, a discharge occurs in the circuit protection element 211 that has cut off the electrical connection due to the voltage drop of the impedance element 25. Since it is possible to reduce the electric field (that is, potential difference) at a location where it is likely to occur, it is possible to suppress the occurrence of discharge current such as arc discharge. Since the possibility of the monitoring circuit 22 being destroyed by the discharge current can be reduced, it is possible to provide the circuit protection unit 20 that can protect the monitoring circuit 22 more reliably than before.

The impedance element 25 is an inductor L (more specifically, Inductors L1 to Ln+1) may also be used.

It is preferable that the inductor L is provided at least on the highest detection line M1, which is the highest potential side of the detection lines M, and the lowest detection line Mn+1, which is the lowest potential side.

The overvoltage protection element 212 and the circuit protection element 211 may be provided on the same circuit board 21, and the inductor L may be provided outside the circuit board 21. This configuration can be easily realized by adding an inductor L to the conventional circuit board 21 including the overvoltage protection element 212 and the circuit protection element 211. Further, the overvoltage protection element 212, the circuit protection element 211, and the inductor L may be provided on the same circuit board 21. By simply installing the circuit board 21 in a power supply system that includes the monitoring circuit 22 and the power supply unit, a power supply system that includes the circuit protection device according to the present application can be realized. Furthermore, the inductor L may be provided both on the circuit board 21 and outside the circuit board.

The impedance element 25 is a resistor R (more specifically may be resistors R1 to Rn+1).

It is preferable that the resistor R is provided at least on either the highest detection line M1 or the lowest detection line Mn+1.

The overvoltage protection element 212 and the circuit protection element 211 may be provided on the same circuit board 21, and the resistor R may be provided outside the circuit board 21. This configuration can be easily realized by adding the resistor R to the conventional circuit board 21 including the overvoltage protection element 212 and the circuit protection element 211. Further, the overvoltage protection element 212, the circuit protection element 211, and the resistor R may be provided on the same circuit board 21. By simply installing the circuit board 21 in a power supply system that includes the monitoring circuit 22 and the power supply unit, a power supply system that includes the circuit protection device according to the present application can be realized. Furthermore, the resistor R may be provided both on the circuit board 21 and outside the circuit board.

The control unit and the method described in the present disclosure are implemented by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. may be done. Alternatively, the controller and techniques described in this disclosure may be implemented by a dedicated computer provided by a processor configured with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described in the present disclosure may be implemented using a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. It may be implemented by one or more dedicated computers configured. The computer program may also be stored as instructions executed by a computer on a computer-readable non-transitory tangible storage medium.

Although the present disclosure has been described based on examples, it is understood that the present disclosure is not limited to the examples or structures. The present disclosure also includes various modifications and equivalent modifications. In addition, various combinations and configurations, as well as other combinations and configurations that include only one, more, or fewer elements, are within the scope and scope of the present disclosure.

Claims

A circuit protection device that protects a monitoring circuit (22) that monitors the voltage of a power supply unit (1),
an overvoltage protection element (212) connected between a plurality of detection lines (M) for voltage detection connecting the power supply unit and the monitoring circuit, and causing a short-circuit failure when an overvoltage is applied;
a circuit protection element (211) provided in each of the plurality of detection lines, which interrupts electrical connection between the power supply section and the monitoring circuit when a current of a predetermined current value or more flows through the detection line;
an impedance (25) provided in at least one of the detection lines and located at a position between the power supply unit and the circuit protection element;
The overvoltage protection element is configured to cause a short-circuit failure and maintain a short-circuit state between the plurality of detection lines when an overvoltage occurs in the power supply section,
The circuit protection element is configured to cut off electrical connection between the power supply unit and the monitoring circuit by a short circuit current flowing between the detection lines via the overvoltage protection element when an overvoltage occurs in the power supply unit. configured to
The impedance is a circuit protection device (20 ).
The impedance is an inductor (L1 to Ln+1) having an inductance that suppresses generation of discharge current when the circuit protection element interrupts the electrical connection between the power supply section and the monitoring circuit due to the short circuit current. A circuit protection device according to claim 1.
The overvoltage protection element and the circuit protection element are provided on the same circuit board (21),
The inductor is provided outside the circuit board or on the circuit board, and is connected to at least the highest detection line (M1) which is the highest potential side of the detection lines and the lowest detection line (Mn+1) which is the lowest potential side of the detection lines. ) The circuit protection device according to claim 2.
The impedance is a resistor (R1 to Rn+1) having a resistance value that suppresses generation of a discharge current when the circuit protection element interrupts the electrical connection between the power supply section and the monitoring circuit due to the short circuit current. ) The circuit protection device according to claim 1.
The overvoltage protection element and the circuit protection element are provided on the same circuit board (21),
The resistor is provided outside the circuit board or on the circuit board, and is connected to at least the highest detection line (M1) which is the highest potential side of the detection lines or the lowest detection line (M1) which is the lowest potential side of the detection lines. 5. The circuit protection device according to claim 4, wherein the circuit protection device is provided on either one of Mn+1).