JP4186218B2 - Secondary battery pack - Google Patents

Description

  The present invention relates to a secondary battery pack that is used as a backup power source for various electronic devices and includes a chargeable / dischargeable lithium ion secondary battery.

  Generally, an uninterruptible power supply that requires a backup power supply has a DC or AC voltage required for the load from the main power supply part of the power supply body as an electronic device when the input voltage from the commercial AC power supply is normally generated. And the secondary battery is charged via the main power supply unit. On the other hand, when the input voltage is significantly reduced or a power failure occurs, the secondary battery as a backup power supply continues to supply power from the main power supply unit to the load. It is like that. As the secondary battery used here, a lead-acid battery has been conventionally used because it is mainly inexpensive and the charge / discharge management is simple.

  4 and 5 are block diagrams showing a schematic configuration of a conventional uninterruptible power supply. In each of these drawings, 1 is a power supply circuit as a main power supply unit to which an AC input voltage Vi from a commercial power supply (not shown) is applied, for example, and this power supply circuit 1 is supplied with an AC or DC output voltage Vo. One to a plurality of loads 3 are connected. Reference numeral 4 denotes a lead storage battery serving as a backup power source for supplying power to the load 3 when the input voltage Vi is lowered or a power failure occurs. The power supply circuit 1 includes a charging circuit 5 that charges the lead storage battery 4 when the input voltage Vi is normal, and a discharge circuit 6 that discharges the lead storage battery 4 and supplies power to the load 3 when the input voltage Vi decreases or when a power failure occurs. Each is incorporated. Here, FIG. 4 shows an example in which the lead storage battery 4 is housed in the main body case 7 which is the main body power supply together with the power supply circuit 1, and FIG. 5 shows the lead storage battery 4 configured separately from the power supply circuit 1. An example is shown.

  The power supply circuit 1 includes an AC / AC converter 11 that converts the AC input voltage Vi into a required AC output voltage Vo to the load 3, and AC / DC conversion that converts the AC input voltage Vi into a DC voltage that is stepped up or down. A DC / DC converter 13 for converting the DC voltage obtained by the unit 12 and the DC voltage obtained by the AC / DC converter 12 into a required DC output voltage Vo to the load 3 is appropriately incorporated.

  By the way, the uninterruptible power supply equipped with the lead storage battery 4 must secure a large battery storage space, and is extremely heavy, and also has various problems due to the use of lead in terms of environment. In order to eliminate such drawbacks, for example, Patent Document 1 proposes an uninterruptible power supply apparatus using a lithium ion secondary battery as a backup power source instead of a lead storage battery. The lithium ion secondary battery here is composed of a battery module in which a plurality of battery cells are connected in series, and a battery protection circuit for preventing overcharge and overdischarge is also incorporated.

Another Patent Document 2 discloses a packaged secondary battery pack that includes an overdischarge protection circuit and an overcharge protection circuit and incorporates a lithium ion secondary battery.
JP 2002-58170 A Japanese Patent No. 2618879

  In the prior art shown in FIGS. 4 and 5, the power supply circuit 1 including the charging circuit 5 and the discharging circuit 6 is designed in advance on the power supply body side in accordance with the specifications of the lead storage battery 4 as a backup power supply. Therefore, when this lead storage battery 4 is replaced with a lithium ion secondary battery shown in Patent Documents 1 and 2, the power supply circuit 1 on the power supply body side must be redesigned, and the existing power supply circuit 1 is used as it is. It was impossible.

  Specifically, for example, when the power supply circuit 1 is designed in accordance with the lead storage battery 4 that is optimally charged with a direct current of 27 V, the supply voltage from the charging circuit 5 to the lead storage battery 4 is the optimum charge of the lead storage battery 4. The voltage is set to 27V. However, when the same power supply voltage as that of the lead storage battery 4 is applied to the lithium ion secondary battery having the same capacity, the life is remarkably reduced (that is, the optimum charging voltage is lower than that of the lead storage battery 4).

  Furthermore, in order to prevent the self-discharge of the lead storage battery 4, the charging circuit 5 needs to be fully charged at all times. However, the lithium ion secondary battery does not self-discharge so much and the supply voltage is continuously supplied from the charging circuit 5. If it is, the life will be shortened. For this reason, when a lithium secondary battery having the same capacity is used in place of the lead storage battery 4 in combination with a high power supply voltage from the charging circuit 5, the maintainability as an uninterruptible power supply device is not guaranteed at all.

  The present invention has been made paying attention to the above problems, and an object of the present invention is to provide a secondary battery pack that can be used as a backup power source for various electronic devices without any problems with existing electronic devices. .

  Another object of the present invention is to provide a secondary battery pack that can extend the life of the lithium ion secondary battery as much as possible by supplying power in accordance with the self-discharge characteristics of the lithium ion secondary battery. There is.

  In the invention according to claim 1, the step-up / step-down unit provided in the secondary battery pack sets the power supply voltage applied from the electronic device to the lithium ion secondary battery to an optimum voltage for charging the lithium ion secondary battery. Step up or down. As described above, the lithium ion secondary battery can be charged with an optimum voltage by simply attaching the secondary battery pack to various electronic devices without any modification in the electronic device.

According to the first aspect of the present invention, when the full charge detection unit provided in the secondary battery pack detects the full charge of the lithium ion secondary battery, the power supply to the lithium ion secondary battery is stopped to perform self-discharge. Let In this way, the life of the lithium ion secondary battery mounted in the secondary battery pack is extended as much as possible by supplying the minimum necessary power to the lithium ion secondary battery that does not need to be constantly supplied. It becomes possible.

Furthermore, in the invention according to claim 1, when the terminal voltage of the lithium ion secondary battery is reduced to a required value corresponding to the backup time guaranteed as an electronic device, for example, until the full charge detection unit detects full charge, Power is supplied to the lithium ion secondary battery. By doing so, the power supply to the electronic device can be continued for a certain period of time during discharging regardless of the state of charge of the lithium ion secondary battery.

In the invention according to claim 1, it is possible to supply power to the load without going through the electronic device by directly connecting the discharge terminal provided in the secondary battery pack to an arbitrary load.

  According to the first aspect of the present invention, it is possible to provide a secondary battery pack that can be used without any problem as a backup power source for various electronic devices without any modification to existing electronic devices.

According to the invention of claim 1 , it is possible to extend the life of the lithium ion secondary battery as much as possible by supplying power according to the self-discharge characteristics of the dilithium ion secondary battery.

Furthermore, according to the first aspect of the present invention, the power supply to the load can be continued for a certain time during the discharge, regardless of the state of charge of the lithium ion secondary battery.

According to the invention of claim 1 , it is possible to directly supply power to the load without going through the electronic device.

  Hereinafter, a preferred embodiment of a secondary battery pack according to the present invention will be described with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the part which is common in FIG.4 and FIG.5 shown in a prior art example, and description of the overlapping part is abbreviate | omitted as much as possible.

  FIG. 1 shows an example in which a novel secondary battery pack 21 according to the present invention is mounted on a power supply circuit 1 (corresponding to an electronic device) of an uninterruptible power supply. In the figure, reference numeral 21 denotes a secondary battery pack attached to the apparatus as a backup power source. Here, in addition to the lithium ion secondary battery 22, an overdischarge protection circuit 23 for preventing overdischarge of the lithium ion battery 22, An overcharge protection circuit 24 for preventing charging is incorporated together. Reference numeral 31 denotes a novel voltage exchange unit according to the present invention, and the voltage exchange unit 31 is integrated into the secondary battery pack 21 together with the lithium ion secondary battery 22.

  The power supply circuit 1 includes an AC / AC conversion unit 11, an AC / DC conversion unit 12, and a DC / DC conversion unit 13, respectively, and a lead storage battery when the input voltage Vi is normal, as shown in the conventional example. Charging circuit 5 for charging 4 and discharging circuit 6 for discharging lead storage battery 4 to supply power 3 to the load when input voltage Vi is reduced or when a power failure occurs. Here, the internal function of the power supply circuit 1 is not changed at all regardless of what secondary battery pack 21 is attached to the power supply circuit 1 by the functions built in the voltage conversion unit 31. Attention.

  The voltage conversion unit 31 is provided as an independent module inside the secondary battery pack 21. In the example shown in FIG. 1, the voltage conversion unit 31 is incorporated in a box-shaped secondary battery pack 21 independent of the main body case 7, but as shown in FIG. A space for storing the battery pack 21 may be provided so that the secondary battery pack 21 can be stored inside the main body case 7. Thus, the secondary battery pack 21 according to the present embodiment can adopt an optimal arrangement according to the size and shape of the main body case 7.

  As shown in FIG. 1 and FIG. 2, the voltage conversion unit 31 in this embodiment is optimal for charging the lithium ion secondary battery 22 with the power supply voltage supplied from the power supply circuit 1 to the lithium ion secondary battery 22. Step-up / step-down unit 32 that steps up or down to an appropriate voltage (optimum charging voltage), a discharge circuit 33 that discharges the lithium ion secondary battery 22 when the input voltage Vi drops or a power failure occurs, and the lithium ion secondary battery 22 is fully charged Is detected, the full-charge detection unit 34 that stops the power supply to the lithium ion secondary battery 22 and self-discharges the lithium ion secondary battery 22, and the terminal voltage of the lithium ion secondary battery 22 reaches the required value. A low voltage detection unit 35 that starts supplying power to the lithium ion secondary battery 22 when it is detected that the voltage has decreased is provided. The configuration of each part will be described in detail below.

  FIG. 3 shows the configuration of the uninterruptible power supply including the secondary battery pack 21 in more detail. In the figure, reference numeral 51 denotes a commercial power source as a supply source of the AC input voltage Vi connected to the input terminals 52 and 52 of the power supply circuit 1, and this input voltage Vi is generated by a filter 53 including a rectifier bridge and a boost chopper circuit. The PFC (power factor correction) circuit 54 is converted to a boosted DC voltage VDC1. That is, the filter 53 and the PFC circuit 54 here correspond to the aforementioned AC / DC converter 12. A DC / DC converter 55 converts the DC voltage VDC1 into one or more DC output voltages Vo1 and Vo2 suitable for the load 3, which corresponds to the DC / DC converter 13. These DC output voltages Vo1 and Vo2 are supplied to the load 3 from an output terminal (not shown) provided in the main body case 7. Note that the number of the DC / DC converter 55 and the DC output voltages Vo1 and Vo2 that can be extracted from the DC / DC converter 55 are not limited to those in the embodiment.

  The DC / DC converter 55 outputs a power supply voltage VCHG for charging the lithium ion secondary battery 22 in addition to the DC output voltages Vo1 and Vo2. On the other hand, a battery converter 56 is connected so as to bypass the DC / DC converter 55 that outputs the power supply voltage VCHG. This is a power supply voltage from the lithium ion secondary battery 22 when the input voltage Vi decreases or when a power failure occurs. Is boosted and the DC voltage VDC2 is supplied to the input side of each DC / DC converter 55. As described above, the power supply circuit 1 shown here functions as an AC / DC unit that converts the AC input voltage Vi into the DC output voltages Vo1 and Vo2, but as an AC / AC unit that supplies an AC output voltage to the load 3. It may be one having the function.

  The secondary battery pack 21 is equipped with a lithium ion secondary battery 22 composed of a plurality of battery cells, detects a voltage generated between the battery cells, and the lithium ion secondary battery 22 A battery protection circuit 61 for monitoring whether or not an overcharged state is reached is incorporated. That is, the battery protection circuit 61 corresponds to the overdischarge protection circuit 23 and the overcharge protection circuit 24. In addition, both ends of the lithium ion secondary battery 22 are connected to the battery connection terminals 62 and 62 of the built-in voltage conversion unit 31, and are connected to the voltage line extending from the lithium ion secondary battery 22 to the battery connection terminals 62 and 62. The fuse 63 that disconnects the lithium ion secondary battery 22 from the voltage conversion unit 31 in the event of an overcurrent, and the lithium ion secondary battery from the voltage conversion unit 31 when the overcharge protection circuit 24 detects overcharge of the lithium ion secondary battery 22. When the first switch element 65 having the diode 64 connected to both ends thereof and the overdischarge protection circuit 23 detects the overdischarge of the lithium ion secondary battery 22 while preventing the current from flowing into the battery 22, the lithium ion secondary battery The current supply from the secondary battery 22 to the voltage conversion unit 31 is blocked, and second switch elements 67 each having a diode 66 connected to both ends thereof are connected.

  In addition to the battery connection terminals 62 and 62 connected to both ends of the lithium ion secondary battery 22, the voltage conversion unit 31 includes main body power supply connection terminals 71 and 71 connected to a voltage line for generating the power supply voltage VCHG of the power supply circuit 1. In addition to the load 3 to which the DC output voltages Vo1 and Vo2 are applied, a discharge terminal 72 to which an arbitrary load 3A is directly connected is provided. The step-up / step-down unit 32 has a function as a charging circuit for charging the lithium ion secondary battery 22, and supplies the power supply voltage VCHG from the DC / DC converter 55 in accordance with the specifications of the lithium ion secondary battery 22. Designed and adjusted to step up or down. Specifically, when it is known in advance that the optimum charging voltage of the lithium ion secondary battery 22 is lower than the power supply voltage VCHG from the DC / DC converter 55, the step-down for stepping down the power supply voltage VCHG to the optimum charging voltage. If a chopper power supply (step-down unit) is incorporated and it is known in advance that the optimum charging voltage of the lithium ion secondary battery 22 is higher than the power supply voltage VCHG from the DC / DC converter 55, the power supply voltage VCHG is A step-up chopper power supply (step-up unit) that boosts the optimum charging voltage is incorporated.

  Further, in order to set / adjust the voltage applied to the lithium ion secondary battery 22 from the boost / buck unit 32 to the optimum charging voltage of the lithium ion secondary battery 22, the input voltage (feed voltage) applied to the voltage conversion unit 31 is adjusted. (VCHG) may be provided, or a means for detecting the terminal voltage of the secondary battery may be provided for a predetermined input voltage.

  The full charge detection unit 34 is connected to both ends of a resistor 74 that detects a charging current supplied from the boost / buck unit 32 to the lithium ion secondary battery 22. The resistor 74 as the current detection element may be composed of other elements. The full charge detection unit 34 here is based on the charging current to the lithium ion secondary battery 22 detected by the resistor 74, and when the lithium ion secondary battery 22 is fully charged, A charge stop signal for stopping the operation is output to the step-up / step-down unit 32. Further, when the low voltage detection unit 35 detects a low voltage state in which the terminal voltage of the lithium ion secondary battery 22 has decreased to a required value due to self-discharge, the low voltage detection unit 35 outputs a charge start signal for starting the operation of the step-up / step-down unit 32. -It outputs to the step-down unit 32. The full charge detection level by the full charge detection unit 34 is configured to be easily variably set according to the specifications of the secondary battery to be used and the power supply circuit 1.

  The discharge circuit 33 bypasses the series circuit composed of the step-up / step-down unit 32 and the resistor 74, and from one battery connection terminal 62, which is the output terminal of the voltage conversion unit 31, to one input terminal of the voltage conversion unit 31. A discharge line 76 is connected to the main body power connection terminal 71 via a diode 75. The diode 75 has a function of preventing the power supply voltage VCHG from the power supply circuit 1 from being directly supplied to the secondary battery pack 21 without passing through the boost / buck unit 32. Preferably, a changeover switch 77 is provided in the middle of the discharge line 76 as switching means for supplying the terminal voltage of the lithium ion secondary battery 22 to either the main body power connection terminal 71 or the discharge terminal 72. Thereby, according to the product (load) to be used, it can be selected whether the electric power supply from the lithium ion secondary battery 22 is via the power supply circuit 1 or not.

  Note that when the power supply voltage VCHG is lower than the optimum charging voltage of the secondary battery and the boost / buck unit 32 performs boosting, the diode 75 from the secondary battery even when the AC input voltage Vi is normally supplied. The current flows into the main body power connection terminal 71 via the, and the mode is not shifted to the mode for charging the secondary battery. Therefore, in this case, it is desirable to connect the cathode of the diode 75 directly to the discharge terminal 72 and separate the charging line and the discharging line separately.

  Next, the operation of the above configuration will be described. When the AC input voltage Vi from the commercial power supply 51 is normally supplied into the power supply circuit 1, the AC input voltage Vi is converted by the filter 53 and the PFC circuit 54. It is converted into a boosted DC voltage VDC1. The DC voltage VDC1 from the PFC circuit 54 is applied to the DC / DC converter 55, and the DC output voltages Vo1 and Vo2 obtained by the DC / DC converter 55 are applied to the load 3 connected to the main body case 7. A power supply voltage VCHG for charging the lithium ion secondary battery 22 is generated from the DC / DC converter 55. The DC output voltages Vo1 and Vo2 and the feeding voltage VCHG are stabilized by a feedback circuit (not shown) built in the DC / DC converter 55.

  On the other hand, when it is desired to supply power to the load 3 for a certain period of time even when the AC input voltage Vi drops or a power failure occurs, the secondary battery pack 21 shown in FIGS. The power supply circuit 1 here is designed with specifications suitable for charging and discharging the lead storage battery 4 in the conventional example. Specifically, the power supply voltage VCHG output from the DC / DC converter 55 is set to 27 VDC which is the optimum charging voltage for the lead storage battery, and when the AC input voltage Vi is applied to the input terminals 52 and 52. The power supply voltage VCHG is always output from the DC / DC converter 55. Therefore, when using the lead storage battery 4 having an optimum charging voltage of 27V DC, both ends of the lead storage battery 4 may be directly connected to the voltage line of the power supply voltage VCHG of the power supply circuit 1.

  On the other hand, when a lithium ion secondary battery 22 other than the lead storage battery 4 is used, the optimum charging voltage of the lithium ion secondary battery 22 is approximately DC 24.6V. A supply voltage VCHG of DC 27V is always supplied to the lithium ion secondary battery 22, and the life of the lithium ion secondary battery 22 is significantly reduced. Therefore, in this case, the main body power connection terminals 71 and 71 of the secondary battery pack 21 having the voltage conversion unit 31 are connected to the voltage line of the power supply voltage VCHG of the power circuit 1. In this way, the power supply voltage VCHG from the DC / DC converter 55 is converted to a direct current 24.6 which is the optimum charging voltage of the lithium ion secondary battery 22 by the step-up / step-down unit 32 (in this case, it is only necessary to have a step-down function) 32. This is converted to V, and the stepped-down DC voltage is supplied to the lithium ion secondary battery 22. Therefore, the lithium ion secondary battery 22 can be charged with an optimum voltage by simply incorporating the secondary battery pack 21 without modifying the inside of the power supply circuit 1.

  Further, the full charge detection unit 34 provided in the voltage conversion unit 31 monitors whether or not the lithium ion secondary battery 22 is in a fully charged state by reducing the charging current flowing through the resistor 74. When the fully charged state of the ion secondary battery 22 is detected, a charge stop signal for stopping the operation is output to the step-up / step-down unit 32 including the step-down chopper circuit. As described above, when the lithium ion secondary battery 22 is fully charged, the power supply from the step-up / step-down unit 32 to the lithium ion secondary battery 22 is stopped, so the lithium ion secondary battery 22 is excessively charged. Can be prevented. In this case, the terminal voltage of the lithium ion secondary battery 22 gradually decreases due to self-discharge, but when the terminal voltage decreases to a required value corresponding to the backup guarantee time of the load 3, the voltage conversion unit 31 is now turned on. The low voltage detection unit 35 provided in the inside outputs a charge start signal that causes the boost / buck unit 32 to start its operation. Therefore, even when the AC input voltage Vi drops or a power failure occurs during the self-discharge of the lithium ion secondary battery 22, it is possible to continue supplying power to the load 3 for a length longer than the backup guarantee time.

  When a lithium ion secondary battery 22 having an optimum charging voltage other than DC 24.6 V is used as a secondary battery, a voltage conversion unit 31 including a booster / buck unit 32 of another specification may be attached. That is, it is preferable that a plurality of types of voltage conversion units 31 are prepared according to the specifications (optimum charging voltage, self-discharge characteristics, etc.) of the lithium ion secondary battery 22 to be used.

  When the AC input voltage Vi decreases or a power failure occurs in the state where the voltage conversion unit 31 is incorporated, the power supply voltage VCHG applied from the DC / DC converter 55 to the main body power connection terminal 71 of the voltage conversion unit 31 also decreases. At this time, if the cathode of the diode 75 is connected to the main body power connection terminal 71 by the changeover switch 77, the diode 75 becomes conductive and power is supplied from the lithium ion secondary battery 22 to the battery converter 56 of the power supply circuit 1. . In response to this, the battery converter 56 boosts the power supply voltage from the lithium ion secondary battery 22 to the DC voltage VDC2 at substantially the same level as the DC voltage VDC1 from the PFC circuit 54, and the DC voltage VDC2 is increased to each DC / DC. This is supplied to the input side of the converter 55. Therefore, the load 3 connected to the output side of the DC / DC converter 55 continues to receive power supply from the lithium ion secondary battery 22. If the cathode of the diode 75 is connected to the discharge terminal 72 by the changeover switch 77, power is not supplied to the load 3 connected to the DC / DC converter 55 but to another load 3A connected to the discharge terminal 72. Is supplied. Thus, the combination of the discharge terminal 72 and the changeover switch 77 can selectively supply power from the lithium ion secondary battery 22 to any one of the loads 3 and 3A. However, when the feeding voltage VCHG is lower than the terminal voltage of the lithium ion secondary battery 22, the booster / buck unit 32 has a boosting function, so that the cathode of the diode 75 is directly connected to the discharge terminal 72 as described above. There must be.

  As described above, in this embodiment, in the secondary battery pack 21 in which the lithium ion secondary battery 22 that is mounted on the power supply circuit 1 that is an electronic device and charges and discharges with the power supply circuit 1 is mounted, A step-up / step-down unit 32 is provided for stepping up or down the power supply voltage VCHG given from 1 to the lithium ion secondary battery 22 to the optimum charge voltage of the lithium ion secondary battery 22.

  In this case, the step-up / step-down unit 32 provided in the secondary battery pack 21 is optimal for charging the lithium ion secondary battery 22 with the power supply voltage VCHG applied to the lithium ion secondary battery 22 from the power supply circuit 1. Step up or down to a voltage. In this way, the lithium-ion secondary battery 22 can be charged with an optimum voltage by simply attaching the secondary battery pack 21 to various electronic devices such as the power supply circuit 1 and without modifying the electronic device. Can do. Therefore, it is possible to provide the secondary battery pack 21 that can be used without any problem as a backup power source for various electronic devices without any modification to existing electronic devices.

  Further, the secondary battery pack 21 of the present embodiment includes a full charge detection unit 34 that, when detecting the full charge of the lithium ion secondary battery 22, stops power supply to the lithium ion secondary battery 22 and performs self-discharge. ing.

  In this case, when the full charge detection unit 34 provided in the secondary battery pack 21 detects the full charge of the lithium ion secondary battery 22, the power supply to the lithium ion secondary battery 22 is stopped and self-discharge is performed. In this way, by providing the minimum necessary power supply to the lithium ion secondary battery 22 that does not need to be constantly supplied, the life of the lithium ion secondary battery 22 can be extended as much as possible.

  Further, when the secondary battery pack 21 of the present embodiment detects that the terminal voltage of the lithium ion secondary battery 22 has dropped to a required value, the low voltage detection that starts feeding the lithium ion secondary battery 22 Part 35 is provided.

  In this case, when the terminal voltage of the lithium ion secondary battery 22 is lowered to a required value corresponding to the backup time of the load 3 guaranteed as an electronic device, for example, the lithium ion secondary battery 22 is charged until the full charge detection unit 34 detects full charge. Power is supplied to the secondary battery 22. By doing so, the power supply to the load 3 connected to the power supply circuit 1 can be continued for a certain time during the discharge, regardless of the state of charge of the lithium ion secondary battery 22.

  Further, the secondary battery pack 21 of the present embodiment discharges the output voltage from the lithium ion secondary battery 22 to the load 3A different from that connected to the power supply circuit 1 without passing through the power supply circuit 1. A terminal 72 is provided.

  In this way, it is possible to supply power to the load 3A without going through the power supply circuit 1 by directly connecting the discharge terminal 72 provided in the voltage conversion unit 31 to an arbitrary load.

  In addition, this invention is not limited to the said Example, A various deformation | transformation implementation is possible in the range of the summary of this invention. For example, the electronic device that uses the secondary battery pack as a backup power source is not limited to the main power circuit of the uninterruptible power supply shown in this embodiment, and any device can be applied.

It is a block block diagram of the uninterruptible power supply device incorporating the secondary battery pack which shows preferable one Embodiment in this invention. It is a block block diagram of the uninterruptible power supply device which shows the modification of FIG. 1 same as the above. FIG. 3 is a more detailed block diagram of the uninterruptible power supply including the secondary battery pack. It is a block block diagram which shows an example of the uninterruptible power supply device in a prior art example. It is a block block diagram which shows another example of the uninterruptible power supply device in a prior art example.

Explanation of symbols

1 Power supply circuit (electronic device)
3A load
21 Secondary battery pack
22 Lithium ion secondary battery
32 Booster / Buck unit
34 Fully charged detector
35 Low voltage detector
72 Discharge terminal

Claims (1)

In a secondary battery pack equipped with a lithium ion secondary battery mounted on an electronic device and charging / discharging with the electronic device,
A step-up / step-down unit for stepping up or stepping down a power supply voltage supplied from the electronic device to the lithium ion secondary battery to an optimum charging voltage of the lithium ion secondary battery ;
Upon detecting full charge of the lithium ion secondary battery, a full charge detection unit that stops power supply to the lithium ion secondary battery and self-discharges,
When detecting that the terminal voltage of the lithium ion secondary battery has dropped to a required value, a low voltage detection unit for starting power supply to the lithium ion secondary battery,
A discharge terminal for supplying an output voltage from the lithium ion secondary battery to a load without going through the electronic device;
A changeover switch for supplying a terminal voltage of the lithium ion secondary battery to either a main body power supply connection terminal or the discharge terminal;
A secondary battery pack comprising:

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