JP2007166697A - Charging type power supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charging type power supply device that can drive an electric apparatus for a long time, and can prevent the lowering of a voltage even if a large current flows into the electric apparatus. <P>SOLUTION: The charging type power supply device 1 comprises a main power supply secondary battery 2, a backup secondary battery 3 that can discharge a large current, and a control means connected to these secondary batteries. The control means has a function that detects that a voltage of the main power supply secondary battery has been lowered to a reference voltage or lower when discharging electricity to the electric apparatus from the main power supply secondary battery, and discharges electricity to the electric apparatus by switching the main power supply secondary battery to the backup secondary battery on the basis of the detection result. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an improvement of a rechargeable power supply device mounted on a device.

  Various electric devices such as mobile phones, notebook personal computers, electrically assisted bicycles, and electric motorcycles have built-in rechargeable power supply devices. Rechargeable power supply devices used in these electrical devices are mainly nickel metal hydride secondary batteries and lithium ion secondary batteries, which are high-capacity batteries that take advantage of high energy density and long-time equipment. Drive is possible.

  By the way, various electric devices usually have a large current flowing at startup. For example, a large current flows at startup in a personal computer. In the case of an electric vehicle, a large current flows in a short time of several seconds after starting. For this reason, a large current is discharged from the rechargeable power supply device mounted on these electric devices. In a rechargeable power supply device having a normal secondary battery, if a large current is discharged, the effect of the internal impedance is generated, and the voltage drop of the battery voltage becomes large, and there is a risk that it becomes impossible to discharge below the overdischarge voltage. There is.

  For this reason, Patent Document 1 discloses a nonaqueous electrolyte secondary battery capable of discharging a large current. By incorporating this secondary battery into the rechargeable power supply device, it is possible to prevent a voltage drop even if a large current flows through the electrical equipment.

However, since the capacity of the nonaqueous electrolyte secondary battery capable of discharging a large current is smaller than that of a normal nonaqueous electrolyte secondary battery, the drive time is limited depending on the type of electric equipment to be mounted.
JP-A-2005-123183

  SUMMARY OF THE INVENTION An object of the present invention is to provide a rechargeable power supply device that can drive an electric device for a long time and can prevent a voltage drop even when a large current flows through the electric device.

According to the present invention, comprising a secondary battery for a main power source, a backup secondary battery capable of discharging a large current, and a control means connected to these secondary batteries,
The control means detects that the voltage of the secondary battery is equal to or lower than a reference voltage when discharging from the main power supply secondary battery to an electrical device, and based on the detection result, the main power supply secondary battery. There is provided a rechargeable power supply device having a function of switching from a secondary battery to the backup secondary battery to discharge the electric device.

  The present invention makes it possible to drive an electric device for a long time, prevent a voltage drop even when a large current flows through the electric device, and achieve continuous driving of the electric device with high reliability and high performance. A rechargeable power supply device can be provided.

  Hereinafter, a rechargeable power supply device according to an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic diagram illustrating a rechargeable power supply device according to an embodiment. The rechargeable power supply device 1 according to the embodiment includes a secondary battery 2 having a large capacity, a backup secondary battery 3 capable of discharging a large current, a controller 4, and first and second switch FETs 5 and 6. I have.

  The main line L1 and the auxiliary line L2 are connected in parallel to each other by two bus lines L3 and L4. The electric device 11 is connected to one end of the main line L1.

  The main power supply secondary battery 2 is connected to the main line L1. The first switch FET 5 is connected to the main line L1 located between the main power source secondary battery 2 and the intersection of the bus line L3 on the electric equipment 11 side. The backup secondary battery 3 is connected to the auxiliary line L2. The second switch FET 6 is connected to the auxiliary line L2 located between the backup secondary battery 3 and the intersection of the bus line L3. Depending on the voltage of the backup secondary battery 3, a booster circuit (not shown) may be connected to the auxiliary line L2 located between the backup secondary battery 3 and the second switch FET 6. .

  The controller 4 is composed of, for example, a microcomputer. The controller 4 is connected to the main line L1 around the main power supply secondary battery 2 through the detection signal lines S1 and S2, and has a function of detecting the voltage of the secondary battery 2. The controller 4 is connected to the first switching FET 5 through the signal line S3, and opens and closes the FET 5. The controller 4 is connected to the second switching FET 6 through a signal line S4, and opens and closes the FET 6. In such a controller 4, the voltage of the secondary battery 2 for main power supply is detected through the detection signal lines S 1 and S 2, and the detected voltage is compared with the reference voltage. The first switching FET 5 is closed, and the second switching FET 6 is opened through the signal line S4. That is, when the voltage of the main power source secondary battery 2 falls below the reference voltage, the secondary battery 2 is switched to the backup secondary battery 3 and connected to the electrical device 11. The reference voltage cannot be generally defined by the voltage of the secondary battery 2 for main power supply, but is preferably set to a voltage that is 80 to 85% lower than the initial voltage of the secondary battery 2 for main power supply.

  The controller 4 has a return function for reconnecting the main power supply secondary battery 2 to the electrical device 11 from the backup secondary battery 3. That is, switching from the main power supply secondary battery 2 to the backup secondary battery 3, the first switch FET 5 is opened through the signal line S 3 after a desired standby time has elapsed, and the first switch FET 5 is opened through the signal line S 4. 2 to close the switch FET 6 and connect the main power supply secondary battery 2 from the backup secondary battery 3 to the electrical device 11. The standby time until the return is made by a timer such as a register of the controller 4, and the standby time is set in consideration of the time during which a large current flows through the electrical device 11, for example.

  As the large-capacity main power source secondary battery 2 and the backup secondary battery 3 capable of discharging a large current, for example, a thin battery having an exterior member made of an aluminum laminate film shown in FIG. 2 is used. Reference numeral 21 in FIG. 4 denotes an outer package member in which a positive electrode and a negative electrode are stacked with a separator sandwiched between them, wound into a spiral shape, and press-molded into a flat electrode group and an electrolytic solution. Reference numeral 22 denotes a positive electrode terminal having one end connected to the positive electrode and the other end extending from one side surface of the exterior member 21. Reference numeral 23 denotes a negative electrode terminal having one end connected to the negative electrode and the other end extending from one side surface of the exterior member 21.

  The secondary battery 2 for main power supply includes, for example, a container such as an exterior member made of an aluminum laminate film, a nonaqueous electrolyte housed in the container, a positive electrode housed in the container, A negative electrode current collector made of copper foil or copper alloy foil is housed and has a negative electrode layer on which a negative electrode layer containing a negative electrode active material made of a carbonaceous material is supported.

  The backup secondary battery 3 preferably has a maximum discharge current of 30 C for 2 minutes. The backup secondary battery 3 preferably has 10C charge, a discharge depth of 100%, and a deterioration at 1000 cycles of 1%. Here, “C” is a unit representing a charge / discharge rate, and a rate that can be calculated in one hour when a constant current charge from complete discharge to full charge (or from full charge to complete discharge) is calculated is expressed as 1C. In the case of 1/10 hour, it is expressed as 10C. Therefore, for example, 10C charging requires 10 times as much current as 1C charging.

  Such a backup secondary battery 3 capable of discharging a large current includes a container such as an exterior member made of, for example, an aluminum laminate film as shown in Patent Document 1 described above, and a nonaqueous electrolyte accommodated in the container. And occludes / releases lithium ions having a particle size distribution with an average particle size of 1 μm or less in a negative electrode current collector made of aluminum foil or aluminum alloy foil and housed in the container and the positive electrode housed in the container. And a negative electrode on which a negative electrode layer containing a material such as lithium titanate as negative electrode active material particles is supported.

  Next, the discharge operation to the electric equipment by the rechargeable power supply device according to the embodiment shown in FIG. 1 will be described.

  The controller 4 opens the first switch FET 5 through the signal line S3, closes the second switch FET 6 through the signal line S4, and connects the main power source secondary battery 2 to the electrical equipment 11 through the main line L1. Then, a predetermined voltage is discharged to the electric device 11 and driven. At this time, the controller 4 detects the voltage of the secondary battery 2 for main power supply through the detection signal lines S1 and S2, and determines whether or not the detected voltage is lower than the reference voltage.

  When it is determined that the detected voltage is equal to or lower than the reference voltage, that is, when a large current flows through the electric device 11 and a voltage drop of the secondary battery 2 for main power supply is determined, the controller 4 passes the first line through the signal line S3. The switch FET 5 is closed, and the second switch FET 6 is opened through the signal line S4. By opening and closing these FETs 5 and 6, the main power supply secondary battery 2 is switched to the backup secondary battery 3, and the backup secondary battery 3 is connected to the electrical equipment 11 through the bus line L3 and the main line L1. Current discharge is performed. The backup secondary battery 3 can discharge a large current (for example, the maximum discharge current is 30 C for 2 minutes), so even if a large current flows through the electrical equipment 11, it maintains an initial voltage without causing a voltage drop. Then, the electric device 11 is driven.

  That is, as shown in FIG. 3 showing the voltage-current characteristics at 50% discharge, a large-capacity secondary battery for main power source, for example, a high-capacity lithium ion secondary battery: 18650 type / 1600 mAh, (characteristic line A) is discharged. When the current becomes high, the voltage drop becomes large. Particularly when the discharge current becomes 5 A, the voltage measurement becomes impossible due to the rapid voltage drop. In contrast, in a secondary battery capable of discharging a large current, for example, a lithium ion secondary battery having a capacity of 600 mAh and a maximum discharge current of 30 C for 2 minutes (characteristic line B in FIG. 3), the discharge current is 30 A A high voltage almost the same as the voltage at 1 A can be maintained. As a result, even if a large current flows through the electrical device 11 as described above, the electrical device 11 can be driven while maintaining the initial voltage without causing a voltage drop.

  After such a large current discharge to the electrical device 11 by the backup secondary battery 3 (after a desired standby time has elapsed), the controller 4 opens the first switch FET 5 through the signal line S3, and The second switch FET 6 is closed through the signal line S4, and the main power supply secondary battery 2 is connected to the electrical device 11 from the backup secondary battery 3 and returned. That is, the stationary electric device 11 is driven by the main power source secondary battery 2.

  As described above, according to the embodiment, when the secondary battery 2 for high-power main power source, the secondary battery for backup 3 capable of discharging a large current, and the main power source secondary battery 2 are discharged to the electrical device 11, It is detected that the voltage of the secondary battery 2 has fallen below the set voltage, and based on the detection result, the secondary battery for main power supply 2 is switched to the secondary battery for backup 3 and discharged to the electric device 11. The controller 4 having a function of performing the operation enables the electric device 11 to be driven for a long time, and switches to the backup secondary battery 3 even when a large current flows through the electric device 11. The drive of the electric equipment 11 can be continued while preventing the descent. As a result, even when a large current flows through the electrical device 11, it is possible to provide a highly reliable and high-performance rechargeable power supply device 1 that achieves continuous driving of the electrical device 11.

  In addition, after the large current discharge to the electrical device 11 by the backup secondary battery 3 (after a desired standby time has elapsed), the controller 4 removes the main power supply secondary battery 2 from the backup secondary battery 3. By performing the restoration to be connected to the electrical device 11, it is possible to prevent the backup secondary battery 3 having a small capacity from being discharged to the electrical device 11 for an unnecessarily long time. As a result, the electric device 11 can be driven for a longer time.

Schematic which shows the rechargeable power supply device which concerns on embodiment of this invention. The front view which shows the secondary battery integrated in the rechargeable power supply device which concerns on embodiment. The voltage-current characteristic view at the time of discharge of 50% in a secondary battery for a large capacity main power source and a secondary battery capable of discharging a large current.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Rechargeable power supply device, 2 ... Secondary battery for large-capacity main power supply, 3 ... Backup secondary battery capable of discharging a large current, 4 ... Controller, 11 ... Electrical equipment, 21 ... Exterior member, 22 ... Positive electrode Terminal, 23 ... negative electrode terminal.

Claims (3)

A secondary battery for main power supply, a backup secondary battery capable of discharging a large current, and a control means connected to these secondary batteries,
The control means detects that the voltage of the secondary battery is equal to or lower than a reference voltage when discharging from the main power supply secondary battery to an electrical device, and based on the detection result, the main power supply secondary battery. A rechargeable power supply device having a function of switching from a secondary battery to the backup secondary battery to discharge the electrical device.   2. The rechargeable power supply device according to claim 1, wherein the secondary battery for backup capable of discharging a large current has 10 C charge, a discharge depth of 100%, and deterioration at 1000 cycles of 1%.   2. The rechargeable power supply device according to claim 1, wherein the control unit further has a return function for connecting the main power supply secondary battery from the backup secondary battery to an electric device.

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