TW201528635A - Protection circuit and battery set - Google Patents

Abstract

The present invention aims to, in an event of abnormal battery units, ensure the overall safety of the circuit and prevent overall shutdown of the circuit to supply the needed power. A protection circuit (1) is in parallel connection with multiple battery stacks (3) which are cascaded with multiple battery units (2), characterized in that each battery stack (2) is assembled with a protection element (5) having a heat generation resistor (14) and a fusible conductor (13) forming a part of charging or discharging current path and being blown out due to the heat of the heat generation resistor (14) or self-generated heat.

Description

Protection circuit, battery pack

The present invention relates to a protection circuit for preventing overcurrent or overvoltage of a battery pack by using a protective element provided with a heating resistor and a fuse element on a substrate.

In recent years, HEV (Hybrid Electric Vehicle) or EV (Electric Vehicle) using batteries and motors has rapidly spread. As a power source of HEV or EV, a lithium ion secondary battery is gradually used from the viewpoint of energy density and output characteristics. In automotive applications, high voltage and high current are required. Therefore, a dedicated unit capable of withstanding high voltage and large current has been developed, but in consideration of manufacturing cost, in most cases, a plurality of battery cells are connected in series and in parallel, and a common unit is used to secure a required voltage and current.

Although the lithium ion secondary battery has excellent characteristics, it is indispensable for the management of charge and discharge characteristics. If the abnormal battery unit is subjected to general treatment, there is a possibility of fire or explosion. Therefore, if there are multiple battery cells, the voltage balance between the cells is very important. If the abnormal cells are included, it will affect other normal cells, and there is a problem that normal charging and discharging cannot be performed.

In order to avoid the above-mentioned situation, most battery systems using lithium ion secondary batteries are equipped with a fuse element connected to a charge and discharge path and a power management system (BMS: Battery Management System) that manages the battery as a whole. The BMS manages the charge and discharge state (voltage, capacity, etc.) of each battery unit, and if an abnormality is detected, the fuse element is externally used using a FET switch or the like. The device transmits a signal to interrupt the output portion of the circuit to avoid the trouble of fire caused by abnormal heat generation.

In recent years, not only the aforementioned state of charge (SOC), but also the battery system management based on the consideration of the battery system's capacity deterioration (SOH: State of Health) and battery life (State of Life). It has also received increasing attention.

Patent Document 1: Japanese Patent No. 4207877

However, in a high-speed moving car, there is a case where a rapid driving force is lowered or an emergency stop is caused, and battery management in an emergency state is also required. For example, even if an abnormality of the battery system occurs during running, in order to avoid danger, it is preferable to continuously supply the driving force for moving to a repair factory or a safe place, or the driving force for warning lamps and air conditioners.

Further, in the battery system in which an abnormality occurs, since the abnormal battery unit exists on the circuit, the possibility of being reused due to some electrical abnormality, malfunction, or the like cannot be completely eliminated. Although the car will be inspected regularly, and the defective battery unit can be replaced at this time, the abnormal battery unit must exist on the circuit during the period before the periodic inspection. If possible, if you can remove it from the circuit, you can get better security.

Furthermore, in the case of HEV or EV use, in addition to the abnormality of the battery system itself, in the event of an emergency such as accident or flooding, it is necessary to interrupt the circuit in order to prevent secondary damage caused by the battery system. Moreover, if the use of the electric power tool is compared with the case where some of the battery cells are abnormal, that is, they are completely undriven, it is preferable to drive even if the output is slightly lowered.

Accordingly, an object of the present invention is to provide a protection element and a battery pack that can supply a required power in a situation in which an abnormality occurs in a battery unit or the like, and the entire circuit is safe and the entire circuit is prevented from being cut off.

In order to solve the above problems, the protection circuit of the present invention has a plurality of battery stacks connected in parallel, and the plurality of battery stacks are connected in series with a plurality of battery cells, wherein a protective element is assembled in the battery stack, and the protection component is provided with heat. A resistor, a fusible conductor that is part of a current path that constitutes a charge or discharge and that is blown by heat of the heat generating resistor or self-heating.

Further, in the battery pack of the present invention, a plurality of battery stacks are connected in parallel, and the plurality of battery stacks are connected in series with a plurality of battery cells, wherein a protective element is provided in the battery stack, and the protective component is provided with a heating resistor, a fusible conductor that is part of a current path constituting charging or discharging and is blown by heat of the heating resistor or self-heating; the protective element of the plurality of battery stacks is individually controlled for each battery stack, whereby only The battery stack with the battery cells that generate the anomalies is removed from the circuit.

According to the present invention, in the case where an abnormality occurs in a part of the battery cells, the battery stack can be removed from the charging and discharging path by blowing the protective element of the battery stack in which the battery unit is assembled, and supplied by the remaining battery stack electric power.

Further, according to the present invention, as the protective element, a protective element including a heat generating resistor and a soluble conductor constituting one of the current paths of charging or discharging and being blown by heat of the heating resistor or self-heating is used. The fuse is blown and the stack of cells can be irreversibly blocked from the circuit.

Furthermore, according to the present invention, it is also possible to set a trigger for heating the heating resistor in addition to the overvoltage, and the battery stack can be blocked from the current path depending on the machine side driven by the battery.

1‧‧‧Protection circuit

2‧‧‧ battery unit

3‧‧‧Battery stacking

5‧‧‧Protection components

6‧‧‧Detection components

7‧‧‧BMS control components

11‧‧‧Insert substrate

12‧‧‧ electrodes

13‧‧‧Solid conductor

14‧‧‧heating resistor

15‧‧‧Insulating components

16‧‧‧heating body extraction electrode

17‧‧‧ Flux

18‧‧‧Heating body electrode

19‧‧‧Cover components

20‧‧‧Battery Pack

25‧‧‧Charging device

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view showing a battery pack in which a protective circuit to which the present invention is applied is formed.

2A is a cross-sectional view showing the configuration of a protective element, and FIG. 2B is a plan view showing the configuration of the protective element.

Figure 3 is a circuit diagram of a protection element.

Fig. 4 is a view showing a configuration example of a battery stack.

Fig. 5 is a view showing another configuration example of the battery stack.

Fig. 6 is a view showing another configuration example of the battery stack.

Fig. 7 is a view showing another configuration example of the battery stack.

Fig. 8 is a view showing another configuration example of the battery stack.

Hereinafter, the protection circuit and the battery pack to which the present invention is applied will be described in detail with reference to the drawings. The present invention is not limited to the embodiments described below, and various modifications can be made without departing from the spirit and scope of the invention. Moreover, the drawings are shown in a schematic manner, and there are cases where the ratio of each size is different from the reality. The specific dimensions and the like should be judged by the following instructions. Further, the drawings naturally contain portions having different dimensional relationships or ratios from each other.

(protect the circuit)

As shown in FIG. 1, the protection circuit 1 to which the present invention is applied has a plurality of battery stacks 3 in which a plurality of battery cells 2 are connected in series, and each battery stack 3 is connected in parallel with each other. Each of the battery stacks 3 is respectively provided with a protection element 5, a detection element 6 for detecting an abnormal voltage of each battery unit 2, and a charge and discharge in the control battery stack 3, and driving the protection element 5 according to the detection result of the detection element 6. BMS control element 7.

Further, each of the battery stacks 3 includes a switch 8 for switching between the charging mode and the discharge mode, a charging diode 9 for discharging a charging current in the charging mode, and a discharge diode 10 for discharging a discharge current in the discharge mode.

(Composition of protective components)

The protective element 5 is formed by a fuse element having a function of blocking a current path by a signal from the control element 7 in order to safely block the output of the battery stack 3, and the fuse element constituting a part of the current path is blown. The current path of the battery stack 3 is irreversibly blocked.

Specifically, as shown in FIG. 2A and FIG. 2B, the protective element 5 includes an insulating substrate 11, a heating resistor 14 laminated on the insulating substrate 11 and covered with the insulating member 15, and electrodes 12 formed at both ends of the insulating substrate 11. (A1), 12 (A2), the heating element extraction electrode 16 laminated on the insulating member 15 so as to overlap the heating resistor 14, and both ends of which are connected to the electrodes 12 (A1), 12 (A2) and connected at the center The fusible conductor 13 of the electrode 16 is taken out from the heating element.

The square insulating substrate 11 is formed of an insulating member such as alumina, glass ceramic, mullite, or zirconia. Further, a material for a printed wiring board such as a glass epoxy substrate or a phenolic substrate may be used, but it is necessary to pay attention to the temperature at which the fuse is blown.

The heating resistor 14 is a conductive member having a high electric resistance value and generating heat when energized, and is made of, for example, W, Mo, Ru or the like. The alloy or the composition, the powder of the compound, the resin binder, and the like are mixed by a screen printing technique to form a paste, and a pattern is formed on the insulating substrate 11 and baked.

The insulating member 15 is disposed so as to cover the heating resistor 14, and the heating element extraction electrode 16 is disposed to face the heating resistor 14 via the insulating member 15. In order to efficiently transfer the heat of the heating resistor 14 to the fusible conductor, the heating resistor 14 and the insulating substrate 11 are provided. The insulating member 15 may be laminated between them.

One end of the heating element extraction electrode 16 is connected to the heating element electrode 18 (P1). Further, the other end of the heating resistor 14 is connected to the other heating element electrode 18 (P2).

The fusible conductor 13 is made of a low-melting-point metal which is rapidly melted by the heat generation of the heating resistor 14 or the self-heating of the fusible conductor 13, and a Pb-free solder containing, for example, Sn as a main component can be preferably used. Further, the meltable conductor 13 may be a laminate of a low melting point metal and a high melting point metal such as Ag, Cu or an alloy containing the like as a main component.

When the protective element 5 is reflowed by laminating the high melting point metal and the low melting point metal, the reflow temperature exceeds the melting temperature of the low melting point metal layer, and even if the low melting point metal layer is melted, the fusible conductor 13 does not become Fuse. The meltable conductor 13 may be formed by forming a low melting point metal into a high melting point metal by a plating technique, and may be formed by using other well-known layering techniques or film formation techniques. Further, the fusible conductor 13 can be connected to the heat generating body lead electrode 16 and the electrodes 12 (A1), 12 (A2) using the low melting point metal solder constituting the outer layer.

Further, in order to prevent oxidation of the low-melting-point metal layer 13b of the outer layer, the protective element 5 may be coated with the flux 17 on substantially the entire surface of the soluble conductor 13. Further, the protective member 5 may be placed on the insulating substrate 11 in order to protect the inside.

The protective element 5 to which the present invention is applied has the circuit configuration shown in FIG. In other words, the protective element 5 is constituted by a circuit including a fusible conductor 13 that is connected in series through the heat generating body lead-out electrode 16 and a heating resistor 14 that fuses the meltable conductor 13 by heat conduction through the connection point through the soluble conductor 13. Further, in the protective element 5, for example, the fusible conductor 13 is connected in series to the charge and discharge current path, and the heating resistor 14 is connected to the BMS control element 7. One of the two electrodes 12 of the protection element 5 is connected to A1 and the other is connected to A2. Moreover, the heating element extracting electrode 16 is connected to The heating body electrode 18 is connected to P1, and the other heating element electrode 18 is connected to P2.

(BMS control element 7 / detection element 6)

The detecting element 6 detects the voltage of each of the battery cells 2. The BMS control element 7 energizes the heating element electrode 18 in accordance with the detection result of the detecting element 6, and fuses the fusible conductor 13 of the protection element 5.

Further, even if the protective element 5 is overcurrent due to an abnormality of the battery unit 2, the soluble conductor 13 can be blown by its own heat to interrupt the current path. Alternatively, the protection element 5 detects an overcurrent by the detecting element 6 and causes the heating resistor 14 to generate heat by the BMS control element 7, so that the fusible conductor 13 can be blown.

As described above, the protective element 5 and the fusible conductor 13 are blown by the heat of the heating resistor 14 or by self-heating, so that the current path can be irreversibly blocked without any influence of abnormal operation of the circuit. Therefore, the function as a protection element can be surely realized. Further, the protective element 5 is operated only by an overcurrent as in the case of a protective element of a fuse type, and can be operated by an abnormal voltage or other factors as described later, and can respond to various events. Further, the protection element 5 maintains the power of the current path in the blocking state without the need for the protection element of the electrical switching method, and can reliably maintain the blocking state.

(Battery)

The battery stack 3 is connected in series with a battery unit 2 that needs to be protected from the influence of overcharge and overdischarge conditions, and constitutes a battery pack 20 that is connected in parallel with the other battery stacks 3 through the positive terminal 3a and the negative terminal 3b. The battery pack 20 is detachably connected to the charging device 25, and the charging voltage from the charging device 25 is applied. The battery pack 20 that is charged by the charging device 25 can operate the electronic device, the EV, or the like by supplying electric power to an electronic device or an EV that operates in a battery.

In addition, the battery pack 20, as shown in FIG. 1, has a battery stack 3 in parallel. A protective element 5 is provided in one part of the current path. The protective element 5 is connected to a BMS control element (not shown) that integrally controls charging and discharging of the entire battery pack 20, and forcibly blocks the entire charge and discharge path of the battery pack 20.

According to this battery pack 20, since a plurality of battery stacks 3 are connected in parallel, the conventional battery unit 2 can be used to constitute a battery requiring a large current and a high voltage HEV or EV. At this time, according to the battery pack 20, in a case where an abnormality occurs in a part of the battery cells 2, the battery stack 3 can be removed from the charge and discharge path by blowing the protective element 5 of the battery stack 3 in which the abnormal battery unit is assembled. And supplying power by the remaining battery stack 3.

Therefore, the battery pack 20 can supply a driving force for moving to a repair factory or a safe place or a driving force for a warning light or an air conditioner even when an abnormality of the battery system occurs during running.

(Configuration example 1 of protection element)

Next, the arrangement of the protective elements 5 in each of the battery stacks 3 will be described. Each battery stack 3, as shown in Figure 4, can be provided with a protective element 5 at the output of the current path. In the battery stack 3 shown in FIG. 4, after the detecting element 6 detects the abnormal voltage of each of the battery cells 2, the heating element electrode 18 of the protective element 5 is energized by the BMS control element 7. Thereby, in the battery stack 3, the heat-generating resistor 14 of the protective element 5 is heated, and the meltable conductor 13 is blown and removed from the current path of the battery pack 20. Therefore, the battery pack 20 can prevent charging and discharging of the battery stack 3, and prevent abnormal heat generation or the like from being prevented. Further, the battery pack 20 can supply a driving force for moving to a repair factory or a safe place or a driving force for a warning light or an air conditioner even when an abnormality of the battery system occurs during driving of the EV or the HEV.

(Configuration Example 2 of Protection Element)

Further, as shown in FIG. 5, each of the battery stacks 3 may be connected between the battery cells 2. According to the battery stack 3 shown in FIG. 5, the protective element 5 near the battery unit 2 where the abnormality is generated can be blown, and the charging and discharging of the abnormal battery unit 2 can be surely prevented, and the abnormal unit can be suppressed. The influence of other battery cells 2 adjacent to it.

Further, as shown in the figure, each battery stack 3 is provided with one protective element 5 for one battery unit 2, and the battery unit 2 and the protective element 5 may be alternately connected. According to the above configuration, the protection element 5 that is close to the abnormal unit can also be blown.

(Configuration Example 3 of Protection Element)

Further, as shown in FIG. 6, each of the battery stacks 3 may be connected to the protective element 5 before and after each of the battery cells 2. The battery stack 3 shown in FIG. 6 can physically separate the abnormal unit from the current path of the battery stack 3 by blowing the protective element 5 connected to the battery unit 2 before the abnormality occurs. Therefore, according to the battery stack 3, charging and discharging of the abnormal battery unit 2 can be more reliably prevented, and the influence on the other battery cells 2 adjacent to the abnormal unit can be surely suppressed.

(Configuration Example 4 of Protection Element)

Further, as shown in FIG. 7, each of the battery stacks 3 may be connected to the protective element 5 between the switch 8 and the charging diode 9. The battery stack 3 shown in Fig. 7 can be physically separated from the current path of the charging mode by blowing the protective element 5 connected between the switch 8 and the charging diode 9. Therefore, according to the battery stack 3, charging of the battery unit 2 that generates an abnormality can be prevented, and discharge can also be performed by the switch 8.

(Configuration Example 5 of Protection Element)

Further, as shown in FIG. 8, each of the battery stacks 3 may be connected to the protection element 5 in the current path of the charging mode and the discharging mode. The battery stack 3 shown in FIG. 8 is in phase with the battery stack 3 shown in FIG. Similarly, the protective element 5 is removed from the current path of the battery pack 20 by blowing it. Therefore, the battery pack 20 can prevent charging and discharging of the battery stack 3, and prevent abnormal heat generation or the like from being prevented.

(Drive trigger of BMS control element 7)

In addition, in the above, the protection element 5 is blown off by detecting the abnormal voltage of the battery unit 2 in the battery stack 3, and the battery stack 3 is cut off from the current path, but as a trigger for blowing the protection element 5, Various settings are made depending on the machine side on which the battery pack 20 is mounted.

For example, when the battery pack 20 is mounted on an EV or an HEV or mounted on a power tool, in addition to the abnormality of the battery unit 2, an impact due to an accident or a temperature rise due to a flood, a fire, or the like may occur. An instruction is sent to the BMS control element 7, and the protection element 5 of each battery stack 3 is blown to block the current path. Further, in the case where the battery unit 2 is particularly deteriorated compared to the other battery unit 2, the protective element 5 may be blown off from the current path in order to suppress the influence of the battery unit 2. Moreover, when the battery pack 20 is used as a household power source, a fire, a collapse due to a large-scale earthquake, or a flood caused by a tsunami, the protective element 5 of each battery stack 3 is blown. The current path can also be interrupted.

1‧‧‧Protection circuit

2‧‧‧ battery unit

3‧‧‧Battery stacking

3a‧‧‧positive terminal

3b‧‧‧Negative terminal

5‧‧‧Protection components

6‧‧‧Detection components

7‧‧‧BMS control components

8‧‧‧ switch

9‧‧‧Charging diode

10‧‧‧Discharge diode

20‧‧‧Battery Pack

25‧‧‧Charging device

Claims (7)

A protection circuit is a battery stack in which a plurality of battery cells are connected in series and is connected in parallel. The battery element is assembled with a protection component, and the protection component is provided with a heating resistor and a charging or discharging device. A fusible conductor that is part of the current path and is blown by the heat of the heating resistor or self-heating. The protection circuit of claim 1, wherein the protection component of each of the battery stacks is connected between the battery cells. The protection circuit of claim 2, wherein the protection element of each battery stack is interactively connected to the battery unit. The protection circuit of claim 3, wherein the protection element is connected before the battery unit of each battery stack. The protection circuit of any one of claims 1 to 4, wherein each of the battery stacks has a switch for switching charging or discharging, and the protection element is connected to a branching path of charging of the switch. The protection circuit of any one of claims 1 to 4, wherein a protection element, a control element for driving the protection element, and an abnormal voltage for detecting the battery unit are respectively assembled in each of the battery stacks Measuring component. A battery pack is a battery stack in which a plurality of battery cells are connected in series and is connected in parallel. The battery pack is assembled with a protection component, and the protection component is provided with a heating resistor and a charging or discharging device. One part of the current path and melted by the heat of the heating resistor or self-heating The breakable fusible conductor; the protective element of the plurality of battery stacks is individually controlled for each battery stack, whereby only the battery stack having the battery cells that generate the abnormality is removed from the circuit.