JP2021164358A - Secondary battery, and rush current handling circuit - Google Patents

Abstract

To provide a secondary battery capable of suppressing rush current at starting.SOLUTION: A secondary battery 100 equipped on a vehicle 200 includes a starter for starting an internal combustion engine, and a key switch 300 for outputting a contact signal at starting the starter 201. The secondary battery includes a rechargeable battery 101, an interface 400, a first switch element 103, a resister 104 connected to the first switch element in parallel, and a second switch element 105 connected in series to the resister. The interface acquires the contact signal. The first switch element forms a closed circuit to disconnect the rechargeable battery from the starter for a predetermined period after acquiring the contact signal, and connect the rechargeable battery to the starter after elapsing a predetermined period. The second switch element forms a closed circuit for connecting the resister, the rechargeable battery and the starter for a predetermined period after acquiring the contact signal.SELECTED DRAWING: Figure 3

Description

Embodiments of the present invention relate to a secondary battery and an inrush current compatible circuit.

In order to start an internal combustion engine including a gasoline engine and a diesel engine, it is necessary to apply a physical external force to forcibly rotate the engine. This is called cranking. For example, in a vehicle, a starter motor (starter motor) is rotated to crank the engine. Cranking energy comes from the in-vehicle battery. The situation is the same for ships and other mobiles.

High-performance secondary batteries, such as lithium-ion batteries, are about to replace the lead batteries used in many existing vehicles. However, when this type of secondary battery is used, it has been found that the inrush current at the time of starting is remarkably large.

"Battery, Rechargeable, Sealed, 6T Lithium-ion", [online], [Search on February 27, 2nd year of Reiwa], Internet, <URL: https://quicksearch.dla.mil/qsDocDetails.aspx?ident_number= 281967>

The inrush current at start-up must be within the specified range. In the existing technology, a circuit breaker is used or a large-capacity semiconductor switch (FET, etc.) is used to break the circuit to prevent the inrush current. However, since the inrush current changes according to the capacity and size of the secondary battery, it is necessary to select or manufacture a circuit breaker accordingly. Since the parts that can be used are limited, the resistance value due to the line length may be used by routing the wiring. For this reason, the size of the device has increased and the cost has increased.
Therefore, an object of the present invention is to provide a secondary battery capable of suppressing an inrush current at the time of starting, and a circuit corresponding to the inrush current.

According to the embodiment, the secondary battery can be mounted on a mobile body including a starter for starting an internal combustion engine and a key switch for outputting a contact signal when the starter is started. The secondary battery includes a storage battery, an interface, a first switch element, a resistor connected in parallel to the first switch element, and a second switch element connected in series with the resistor. The interface acquires the contact signal. The first switch element disconnects the storage battery from the starter for a predetermined period after the contact signal is acquired, and forms a closed circuit for connecting the storage battery and the starter after the predetermined period elapses. The second switch element forms a closed circuit that connects the resistor, the storage battery, and the starter only for the above-mentioned predetermined period after the contact signal is acquired.

FIG. 1A is a graph for explaining the inrush current at the time of starting the starter. FIG. 1B is a graph for explaining the inrush current at the time of starting the starter. FIG. 2 is a schematic view showing an example of the secondary battery according to the embodiment. FIG. 3 is a circuit diagram showing an example of the secondary battery according to the embodiment. FIG. 4 is a diagram showing a state of the secondary battery shown in FIG. 3 after 1 second has elapsed from the operation of the key switch 300. FIG. 5 is a timing chart for explaining the operation of the secondary battery 100 according to the embodiment. FIG. 6 is a graph showing an example of the current value flowing through the starter 201 from the operation of the key switch 300. FIG. 7 is a circuit diagram showing a conventional secondary battery for comparison. FIG. 8 is a timing chart showing the operation of the existing secondary battery. FIG. 9 is a graph showing an example of the current value at the time of starting flowing through the existing secondary battery.

1A and 1B are graphs for explaining the inrush current at the start of the starter. In each graph, the vertical axis shows the current value per rotation speed and the voltage. The horizontal axis indicates time [seconds (sec)]. The dotted line indicates the upper limit of the current defined by the standard.

As shown in FIG. 1A, if no countermeasure is taken, a peak current exceeding the standard will be generated when the starter is started. This peak current causes an inrush current in the battery and the mounted moving body (for example, a vehicle), so that the protection circuit interrupts the circuit (upper limit of 2000A).

As shown in FIG. 1B, it is possible to suppress the inrush current at the time of starting by changing the specifications of the FET of the protection circuit provided in the battery. However, it is difficult in reality because it deviates from the specifications defined as the standard. It is desirable to be able to suppress the inrush current without changing the specifications. In the following, technologies that can solve such needs will be described.

FIG. 2 is a schematic view showing an example of the secondary battery according to the embodiment. In the embodiment, the secondary battery 100 is mounted on a vehicle 200 that obtains a driving force by an internal combustion engine (engine). When the key switch (ignition switch (IGN)) 300 installed near the steering wheel of the vehicle 200 is operated, the electric power of the secondary battery 100 is supplied to the starter to start the engine. At that time, the contact signal (starter information) is supplied from the key switch 300 to the secondary battery 100 via the interface 400.

That is, the secondary battery 100 according to the embodiment includes not only a power terminal but also an interface for acquiring at least a signal from the outside. It is possible to control the operation of the secondary battery 100 by giving, for example, a contact signal from the interface.

FIG. 3 is a circuit diagram showing an example of the secondary battery according to the embodiment. FIG. 3 shows a state in a predetermined period (1 second) after the contact signal is given. The vehicle 200 shown in FIG. 3 includes a key switch 300, a starter 201 for starting an engine, a capacitor 202 for stabilizing the operation of the starter 201, and various electrical components 203. The key switch 300 is connected to the interface 400 of the secondary battery 100.

The secondary battery 100 includes, for example, a lithium ion type storage battery 101 and a charging circuit 102 for charging the storage battery 101. The storage battery 101 is connected to a FET (Field Effect Transistor) type FET switch 103 that can withstand a large amount of electric power. The FET switch 103 shall have characteristics within the range specified in the standard. Further, the FET switch 103 is connected in series with the storage battery 101 to form a discharge circuit.

The charging circuit 102 includes a resistor 104 connected in parallel to the FET switch 103, and a FET switch 105 connected in series with the resistor 104. The FET switch 105 turns on the resistor 104 for the predetermined period (1 second) after the contact signal is acquired from the key switch 300. As a result, a closed circuit for connecting the storage battery 101, the starter 201, and the resistor 104 is formed only for one second from the operation of the key switch 300.

Both the FET switch 103 and the FET switch 105 can acquire the contact signal from the key switch 300 via the interface 400.

As shown in FIG. 3, the FET switch 103 is turned off and the FET switch 105 is turned on until one second has elapsed after the key switch 300 is operated. As a result, the resistor 104 is interposed in the power supply system from the storage battery 101 to the starter 201.

FIG. 4 is a diagram showing a state of the secondary battery shown in FIG. 3 after 1 second has elapsed from the operation of the key switch 300. As shown in FIG. 4, when 1 second has elapsed from the operation of the key switch 300, the FET switch 103 is turned on and the FET switch 105 is turned off. As a result, the resistor 104 is disconnected from the power supply system from the storage battery 101 to the starter 201.

FIG. 5 is a timing chart for explaining the operation of the secondary battery 100 according to the embodiment. When the key switch 300 (IGN) is operated, the FET switch 105 is turned on and the FET switch 103 is turned off. Therefore, the resistance value of the resistor 104 avoids the inrush current (for example, 2000A) at the initial stage of startup. After this state continues for 1 second, the FET switch 105 is turned off and the FET switch 103 is turned on. As a result, the current from the storage battery 101 to the starter 201 is stable at, for example, 600 A. The engine can be started by continuing this state for about 30 seconds, for example.

FIG. 6 is a graph showing an example of the current value flowing through the starter 201 from the operation of the key switch 300. According to the embodiment, the current value can be suppressed to less than 2000A from the turning on of the key switch 300 to the starting of the engine. Of course, the inrush current is sufficiently suppressed.

FIG. 7 is a circuit diagram showing a conventional secondary battery for comparison. The existing secondary battery does not have an interface for acquiring a signal from the key switch 300, and cannot acquire a contact signal at the time of starting. The FET switch 105 is turned on only when the storage battery 101 is charged, and is not involved in starting the engine. Although it is the FET switch 500 that is involved in starting the engine, the resistor 104 cannot be connected to the storage battery 101.

As shown in FIG. 8, at the time of starting, the current flowing through the starter 201 flows directly through the FET 500. Therefore, as shown in FIG. 9, the current flowing through the FET switch 500 exceeds the standard value until at least one second has elapsed from the operation of the key switch 300. That is, the inrush current can be suppressed only by changing the specifications of the FET switch 500.

When a lead-acid battery is used, there is no particular problem even if an inrush current is generated due to its characteristics, and a current spike of, for example, 2500 A is allowed. However, when a high-performance storage battery typified by a lithium-ion battery is used, the generation of inrush current is regarded as a problem. In the future, it is hoped that the inrush current can be suppressed when applied to various vehicles.

Therefore, in the embodiment, the contact signal (starter information) can be acquired from the key switch 300, and the on / off timing of the FET switches 103 and 105 is controlled based on the contact signal. That is, from the moment when the power supply to the starter 201 was started until 1 second passed, the FET switch 103 connected in series to the storage battery 101 was turned off, and the FET switch 103 connected in parallel to the storage battery 101 was connected in series. The FET switch 105 is turned on. As a result, the resistor 104 is interposed in the closed circuit, and the inrush current is suppressed by the resistance value. After 1 second has elapsed, the FET switch 103 is turned on, the FET switch 105 is turned off, and the resistor 104 is disconnected from the feeding circuit. As a result, the starter 201 can be driven without loss.

From these facts, according to the embodiment, it becomes possible to provide a secondary battery capable of suppressing the inrush current at the time of starting, and a circuit corresponding to the inrush current.
Although embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. This novel embodiment can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. This embodiment and its modifications are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

100 ... secondary battery, 101 ... storage battery, 102 ... charging circuit, 103 ... FET switch, 104 ... resistor, 105 ... FET switch, 200 ... vehicle, 201 ... starter, 202 ... capacitor, 203 ... electrical equipment, 300 ... key Switch, 400 ... interface, 500 ... FET switch.

Claims (6)

A secondary battery that can be mounted on a moving body including a starter for starting an internal combustion engine and a key switch for outputting a contact signal when the starter is started.
With a storage battery
An interface for acquiring the contact signal and
A first switch element that disconnects the storage battery from the starter for a predetermined period after the contact signal is acquired, and forms a closed circuit that connects the storage battery and the starter after the elapse of the period.
A resistor connected in parallel to the first switch element and
A secondary battery that is connected in series with the resistor and includes a second switch element that forms a closed circuit that connects the resistor, the storage battery, and the starter only for the period after the contact signal is acquired. .. The secondary battery according to claim 1, further comprising the first switch element and comprising a discharge circuit for connecting the storage battery to the starter. The secondary battery according to claim 1, further comprising the second switch element and comprising a charging circuit for charging the storage battery. An interface that acquires the contact signal from a key switch that outputs a contact signal when the starter, which is powered by a storage battery and starts the internal combustion engine, is started.
A first switch element that disconnects the storage battery from the starter for a predetermined period after the contact signal is acquired, and forms a closed circuit that connects the storage battery and the starter after the elapse of the period.
A resistor connected in parallel to the first switch element and
Inrush current compatible, comprising a second switch element that is connected in series with the resistor and forms a closed circuit that connects the resistor, the storage battery, and the starter only for the period after the contact signal is acquired. circuit. The inrush current-corresponding circuit according to claim 4, further comprising a discharge circuit that includes the first switch element and connects the storage battery to the starter. The inrush current-corresponding circuit according to claim 4, further comprising a charging circuit for charging the storage battery, including the second switch element.

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