JP2007236017A - Battery system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery system that can prevent the life of a battery from being shortened even if voltage application is continued. <P>SOLUTION: The battery system comprises: a battery module C to which a plurality of unit cells are connected in series; a charging switch S1 that is arranged between a charging terminal 11 fed with power from the outside and a positive electrode of the battery module; a diode D2 whose cathode is connected to a discharging terminal 12 that feeds power to the outside; and a discharging switch S2 that is arranged between an anode of the diode and the positive electrode of the battery module. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a battery system in which a plurality of secondary batteries are connected in series, and more particularly to a technique for extending the life of a secondary battery.

  FIG. 4 is a diagram illustrating a configuration of a conventional battery system 10 and illustrates an example of a system in which the battery system 10 is used as an uninterruptible power supply (UPS). In this system, power is supplied from the charging circuit 2 a to the application 30 through the power line 4 and the battery system 10. The application 3a includes, for example, an inverter and a target device (load) to which power is supplied from the inverter.

  The charging terminal 11 of the battery system 10 is connected to the charging circuit 2a via the power supply line 4, and the common terminal 13 is grounded. The discharging terminal 12 of the battery system 10 is connected to the constant voltage source 2 b and the application 30. The battery system 10 includes a charging switch S1, a discharging switch S2, and a battery module C. One terminal of the charging switch S1 is connected to the charging terminal 11, and the other terminal is connected to the positive electrode of the battery module C.

One terminal of the discharge switch S2 is connected to the discharge terminal 12, and the other terminal is connected to the positive electrode of the battery module C. The battery module C is composed of n (n is a positive integer) single cells C _{1 to} C _n connected in series, and each single cell is composed of a lithium ion secondary battery. As described above, the positive electrode of the battery module C is connected to the other terminal of the charging switch S1 and the other terminal of the discharging switch S2, and the negative electrode is connected to the common terminal 13.

In the conventional battery system 10 configured as described above, the charging switch S1 is configured such that one or more voltages of the n unit cells C _{1 to} C _n constituting the battery module C have a lower limit value (for example, 2 .5V), the battery module C is charged by the charging circuit 2a. Then, when the voltage of the battery module C reaches an upper limit value (for example, 4.3 V), the charging switch S1 is turned off.

  The constant voltage source 2b converts an AC voltage of an AC power source (not shown) into a DC voltage and outputs a constant DC voltage. The discharge switch S2 is normally turned on by a control signal from the application 30 when power is supplied from the constant voltage source 2b to the application 30. Thereby, even if the power supply from the constant voltage source 2b to the application 30 is stopped, the power is supplied from the battery system 10 to the application 30.

As a related technique, Patent Document 1 discloses an overcharge / overdischarge prevention device capable of preventing overcharge and overdischarge of a non-aqueous secondary battery. The overcharge / overdischarge prevention device includes voltage detection means for detecting a voltage between both ends of each battery, and switch means provided in series with the battery between the charge terminals and between the discharge terminals. When the voltage of each battery exceeds a predetermined value, the switch means is turned off based on the individual output of the voltage detection means to cut off the charging current. When each battery becomes equal to or less than a predetermined value during discharging, the switch means is turned off based on the output of the voltage detecting means to cut off the discharge current.
JP 2003-134676 A

  However, in the conventional battery system described above, since the discharge switch S2 is normally turned on, the voltage from the constant voltage source 2b is continuously applied to the battery module C. As a characteristic of a lithium ion secondary battery, there is a problem that if a voltage is continuously applied, a very weak current continues to flow and the battery life is shortened.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a battery system capable of preventing the battery life from being shortened even when voltage application is continued.

  In order to solve the above problem, the invention according to claim 1 is provided between a battery module in which a plurality of single cells are connected in series, a charging terminal to which power is supplied from the outside, and a positive electrode of the battery module. A charging switch that is opened and closed based on the voltage of each of the plurality of single cells, a diode having a cathode connected to a discharging terminal that supplies power to the outside, and an anode of the diode and a positive electrode of the battery module And a discharge switch provided.

  The invention according to claim 2 is provided with a plurality of battery units to which each charging terminal and discharging terminal are connected in common, and each of the plurality of battery units has a plurality of single cells connected in series. And a charging switch provided between a charging terminal to which power is supplied from the outside and the positive electrode of the battery module, and opened and closed based on the voltage of each of the plurality of single cells, and for discharging to supply power to the outside A diode having a cathode connected to the terminal, and a discharging switch provided between the anode of the diode and the positive electrode of the battery module, and the plurality of charging switches respectively provided in the plurality of battery units are exclusively A control circuit for sequentially turning on is provided.

  According to the first aspect of the present invention, the diode is reverse-biased when the discharging switch is turned on, so that no external voltage is applied to the battery module. Therefore, since a weak current does not continue to flow through the battery module, the battery life can be prevented from being shortened.

  According to the second aspect of the present invention, since the charging switches of the plurality of battery units are sequentially turned on sequentially, the charging current does not flow simultaneously to the battery modules included in each battery unit. Therefore, the power supply capacity of the external power supply that supplies power to the battery system can be reduced.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, constituent elements that are the same as or equivalent to those in the conventional battery system described in the background art section are denoted by the same reference numerals as those used in the background art section.

  FIG. 1 is a diagram illustrating a configuration of a battery system 1 according to a first embodiment of the present invention, and illustrates an example of a system in which the battery system 1 is used as an uninterruptible power supply device.

  In this system, power is supplied from the constant voltage circuit 2 to the application 3 a via the power supply line 4. The application 3a includes, for example, an inverter and a target device (load) to which power is supplied from the inverter. The battery system 1 a is connected to the power line 4.

The charging terminal 11 and the discharging terminal 12 of the battery system 1a are connected to the power supply line 4, and the common terminal 13 is grounded. The battery system 1a includes a charging diode D1, a charging switch S1, a discharging diode D2, a discharging switch S2, a battery module C, voltage detection units 14 _{1 to} 14 _n and a voltage monitoring unit 15.

  The anode of the charging diode D1 is connected to the charging terminal 11, and the cathode is connected to one terminal of the charging switch S1. The other terminal of the charging switch S1 is connected to the positive electrode of the battery module C. The on / off of the charging switch S1 is controlled by a control signal from the voltage monitoring unit 15. Note that the charging diode D1 is not necessarily provided and is an option.

  The cathode of the discharge diode D2 is connected to the discharge terminal 12, and the anode is connected to one terminal of the discharge switch S2. The other terminal of the discharge switch S2 is connected to the positive electrode of the battery module C. The on / off of the discharge switch S2 is controlled by a control signal from the application 3.

The battery module C is composed of n (n is a positive integer) single cells C _{1 to} C _n connected in series, and each single cell is composed of a lithium ion secondary battery. As described above, the positive electrode of the battery module C is connected to the other terminal of the charging switch S1 and the other terminal of the discharging switch S2, and the negative electrode is connected to the common terminal 13.

Voltage detectors 14 _{1 to} 14 _n are connected to both ends of the single cells C _{1 to} C _n , respectively. The voltage detection units 14 _{1 to} 14 _n detect the voltages at both ends of the single cells C _{1 to} C _n , and send them to the voltage monitoring unit 15. The voltage monitoring unit 15 turns off the charging switch S1 when any of the plurality of voltages detected by the voltage detection units 14 _{1 to} 14 _n reaches an upper limit value (for example, 4.3 V), and sets the lower limit value (for example, When the voltage reaches 2.5V), the charging switch S1 is turned on.

Next, operation | movement of the battery system 1a which concerns on Example 1 of this invention comprised as mentioned above is demonstrated. In this battery system 1a, the voltage monitoring unit 15 is sent from the voltage detector 14 ₁ to 14 _n, it monitors the voltage across the unit cell C ₁ -C _n. When one or more of the voltages sent from the voltage detection units 14 _{1 to} 14 _n reach a lower limit value (for example, 2.5 V), the charging switch S1 is turned on.

Thereby, a voltage is applied to the battery module C from the constant voltage circuit 2 through the charging terminal 11, the charging diode D1, and the charging switch S1, and the battery module C is charged. As a result, overdischarge of the battery module C is prevented. On the other hand, the voltage monitoring unit 15 turns off the charging switch S1 when one or more of the voltages sent from the voltage detection units 14 _{1 to} 14 _n reach an upper limit value (for example, 4.3 V). Thereby, overcharging of the battery module C is prevented.

  The discharge switch S2 is normally turned on by a control signal from the application 3a when power is supplied from the constant voltage circuit 2 to the application 3a. As a result, when the power supply from the constant voltage circuit 2 to the application 3a is stopped, the power is supplied from the battery module C to the application 3a via the discharge switch S2, the discharge diode D2, and the discharge terminal 12. As a result, even if the power supply from the constant voltage circuit 2 is stopped, the application 3a can continue to operate because the power is supplied from the battery system 1a.

  According to the above configuration, since the discharge diode D2 is reverse-biased when the discharge switch S2 is turned on, the voltage from the constant voltage circuit 2 is not applied to the battery module C. Therefore, since a weak current does not continue to flow through the battery module C, the problem that the battery life is shortened can be solved.

  The battery system 1b according to the second embodiment of the present invention is a battery system 1 that includes the battery system 1a according to the first embodiment as one battery unit and includes a plurality of the battery units.

  FIG. 2 is a diagram illustrating a configuration of the battery system 1 according to the second embodiment of the present invention, and illustrates an example of a system in which the battery system 1b is used as an uninterruptible power supply. The battery system 1b is composed of three battery units, a first battery unit 20a, a second battery unit 20b, and a third battery unit 20c.

  In addition, although Example 2 demonstrates the battery system 1b which consists of three battery units, the number of the battery units which comprise the battery system 1b is not restricted to three, and if it is two or more, it is arbitrary.

The first battery unit 20a, the charge diode D1, charging switches S1, discharging diode D2, the discharge switch S2, the battery consists of a plurality of single cells Ca ₁ to CA _n module Ca, voltage detector 14a ₁ to 14A _n And a master voltage monitoring unit 15a. The first battery unit 20a is the same as the battery system according to the first embodiment, except that the voltage monitoring unit 15 of the first embodiment is changed to a master voltage monitoring unit 15a.

The battery module Ca and the voltage detection section 14a ₁ to 14A _n respectively correspond to the battery module C and the voltage detection unit 14 ₁ to 14 _n in the first embodiment.

Master voltage monitoring unit 15a corresponds to the control circuit of the present invention, a plurality of voltage detected by the voltage detecting unit 14a ₁ to 14A _n, from the signal and a slave voltage monitoring unit 15c is sent from the slave voltage monitoring unit 15b Based on the transmitted signal, control is performed to exclusively turn on the charging switch S1, the charging switch S3, and the charging switch S5. Details of the master voltage monitoring unit 15a will be described later.

The second battery unit 20b includes a charging diode D3, a charging switch S3, a discharging diode D4, a discharging switch S4, a battery module Cb including a plurality of single cells Cb _{1 to} Cb _n , and voltage detection units 14b _{1 to} 14b _n. And a slave voltage monitoring unit 15b. The second battery unit 20b is the same as the battery system according to the first embodiment, except that the voltage monitoring unit 15 of the first embodiment is changed to a slave voltage monitoring unit 15b.

The charging diode D3, the charging switch S3, the discharging diode D4, the discharging switch S4, the battery module Cb, and the voltage detection units 14b _{1 to} 14b _n are the charging diode D1, the charging switch S1, This corresponds to the discharge diode D2, the discharge switch S2, the battery module C, and the voltage detection units 14 _{1 to} 14 _n , respectively.

The slave voltage monitoring unit 15b outputs a signal for turning on the charging switch S1 when any of the plurality of voltages detected by the voltage detection units 14b _{1 to} 14b _n reaches a lower limit value (for example, 2.5 V). A signal for turning off the charging switch S1 is generated and sent to the master voltage monitoring unit 15a when the upper limit value (for example, 4.3 V) is reached.

The third battery unit 20c, the charging diode D5, charging switch S5, discharging diode D6, the discharge switch S6, composed of a plurality of single cells Cc ₁ to CC _n battery module Cc, the voltage detecting unit 14c ₁ ~14c _n And a slave voltage monitoring unit 15c. The third battery unit 20c is the same as the battery system according to the first embodiment except that the voltage monitoring unit 15 according to the first embodiment is changed to a slave voltage monitoring unit 15c.

The charging diode D5, charging switch S5, discharging diode D6, the discharge switch S6, the battery module Cc and the voltage detection unit 14c ₁ ~14c _n is charge diode D1, charge switch S1 of Example 1, This corresponds to the discharge diode D2, the discharge switch S2, the battery module C, and the voltage detection units 14 _{1 to} 14 _n , respectively.

Slave voltage monitoring unit 15c is configured to generate a signal for turning on the charging switch S5 if any of the plurality of voltage detected by the voltage detecting unit 14c ₁ ~14c _n becomes the lower limit, the upper limit In this case, a signal for turning off the charging switch S5 is generated and sent to the master voltage monitoring unit 15a.

Next, operation | movement of the battery system 1b which concerns on Example 2 of this invention comprised as mentioned above is demonstrated. In this battery system 1b, the master voltage monitoring unit 15a of the first battery unit 20a includes a voltage detecting unit 14a ₁ to 14A _n in the detected voltage of the unit cell Ca ₁ -C _n a, slave voltage of the second battery unit 20b The signal sent from the monitoring unit 15b and the signal sent from the slave voltage monitoring unit 15c of the third battery unit 20c are monitored in a time division manner.

  That is, as shown in FIG. 3, the master voltage monitoring unit 15a monitors the voltage of the battery module Ca of the first battery unit 20a in the period T1, and the voltage of the battery module Cb of the second battery unit 20b in the period T2. In the period T3, the voltage of the battery module Cc of the third battery unit 20c is monitored.

Specifically, in the period T1, the master voltage monitoring unit 15a of the first battery unit 20a has a case where one or more of the voltages sent from the voltage detection units 14 _{1 to} 14 _n become the lower limit value. Then, the charging switch S1 is turned on. Thereby, a voltage is applied from the constant voltage circuit 2 to the battery module Ca through the charging terminal 11a, the charging diode D1, and the charging switch S1, and the battery module Ca is charged. As a result, overdischarge of the battery module Ca is prevented.

On the other hand, the master voltage monitoring unit 15a turns off the charging switch S1 when one or more of the voltages sent from the voltage detection units 14 _{1 to} 14 _n reach an upper limit value. Thereby, overcharging of the battery module C is prevented.

In the period T2, the master voltage monitoring unit 15a of the first battery unit 20a receives signals transmitted from the slave voltage monitoring unit 15b of the second battery unit 20b from the voltage detection units 14b _{1 to} 14b _n. When one or more of the voltages indicates the lower limit value, the charging switch S3 is turned on. Thereby, a voltage is applied from the constant voltage circuit 2 to the battery module Cb via the charging terminal 11b, the charging diode D3, and the charging switch S3, and the battery module Cb is charged. As a result, overdischarge of the battery module Cb is prevented.

On the other hand, the master voltage monitoring unit 15a determines that one or more of the voltages transmitted from the voltage detection units 14b _{1 to} 14b _n has reached the upper limit value from the signal transmitted from the slave voltage monitoring unit 15b. In the case shown, the charging switch S3 is turned off. Thereby, overcharging of the battery module Cb is prevented.

In the period T3, the master voltage monitoring unit 15a of the first battery unit 20a receives a signal transmitted from the slave voltage monitoring unit 15c of the third battery unit 20c from the voltage detection units 14c _{1 to} 14b _n. When one or more of the voltages indicates a lower limit value, the charging switch S5 is turned on. Thereby, a voltage is applied from the constant voltage circuit 2 to the battery module Cc via the charging terminal 11c, the charging diode D5, and the charging switch S5, and the battery module Cc is charged. As a result, overdischarge of the battery module Cc is prevented.

On the other hand, the master voltage monitoring unit 15a that the signal sent from the slave voltage monitoring unit 15c is, one or more of the voltages sent from the voltage detecting unit 14c ₁ ~14c _n becomes the upper limit value In the case shown, the charging switch S5 is turned off. Thereby, overcharging of the battery module Cc is prevented.

  In the period T1 to T3, the discharge switch S2, the discharge switch S4, and the discharge switch S6 are normally supplied with a control signal from the application 3b when power is supplied from the constant voltage circuit 2 to the application 3b. Is turned on.

  Therefore, when power supply from the constant voltage circuit 2 to the application 3b is stopped, power is supplied from the battery module Ca to the application 3b via the discharge switch S2, the discharge diode D2, and the discharge terminal 12a. Power is supplied from the battery module Cb to the application 3b via the discharge switch S4, the discharge diode D4, and the discharge terminal 12b, and the discharge switch S6, the discharge diode D6, and the discharge terminal 12c are further supplied from the battery module Cc. Through this, power is supplied to the application 3b. As a result, even if the power supply from the constant voltage circuit 2 is stopped, the application 3b can continue to operate because the power is supplied from the battery system 1.

  According to the above configuration, in the first battery unit 20a, the discharge diode D2 is reverse-biased when the discharge switch S2 is on, so that the voltage from the constant voltage circuit 2 is applied to the battery module Ca. It will not be done. Therefore, since a weak current does not continue to flow through the battery module Ca, the problem that the life of the single cells constituting the battery module Ca is shortened can be solved. The same applies to the second battery unit 20b and the third battery unit 20c.

  Further, according to the above configuration, the charging switch S1 of the first battery unit 20a, the charging switch S3 of the second battery unit 20b, and the charging switch S5 of the third battery unit 20c are as shown in FIG. Since the transistors are sequentially turned on exclusively, the charging current does not flow through the battery module Ca, the battery module Cb, and the battery module Cc at the same time. Therefore, the power supply capacity of the constant voltage circuit 2 can be reduced.

  The battery system according to the present invention can be used for a wireless power failure power supply device.

It is a figure which shows the structure of the battery system which concerns on Example 1 of this invention. It is a figure which shows the structure of the battery system which concerns on Example 2 of this invention. It is a timing chart which shows operation | movement of the battery system which concerns on Example 2 of this invention. It is a figure which shows the structure of the conventional battery system.

Explanation of symbols

1 cell system 2 constant voltage circuit 3 Application 4 power lines 11, 11a, 11b, 11c charging terminals 12, 12a, 12b, 12c discharging terminals 13, 13a, 13b, 13c common terminal 14 ₁ ~14 _n, 14a ₁ ~ _{14a n, 14b 1 ~14b n,} 14c 1 ~14c n voltage detector 15 voltage monitoring unit 15a master voltage monitoring unit 15b, 15c slave voltage monitoring unit _{C 1 ~C n, Ca 1 ~Ca} n, Cb 1 ~Cb n , Cb _{1 to} Cb _n Battery modules D1, D3, D5 Charging diodes D2, D4, D6 Discharging diodes S1, S3, S5 Charging switches S2, S4, S6 Discharging switches

Claims (3)

A battery module in which a plurality of single cells are connected in series;
A charging switch provided between a charging terminal to which power is supplied from the outside and a positive electrode of the battery module, and opened and closed based on a voltage of each of the plurality of single cells;
A diode having a cathode connected to a discharging terminal for supplying power to the outside;
A discharge switch provided between the anode of the diode and the positive electrode of the battery module;
A battery system comprising: A plurality of battery units each having a charging terminal and a discharging terminal connected in common,
Each of the plurality of battery units is
A battery module in which a plurality of single cells are connected in series;
A charging switch provided between a charging terminal to which power is supplied from the outside and a positive electrode of the battery module, and opened and closed based on a voltage of each of the plurality of single cells;
A diode having a cathode connected to a discharging terminal for supplying power to the outside;
A discharge switch provided between the anode of the diode and the positive electrode of the battery module;
A control circuit for sequentially and sequentially turning on a plurality of charging switches respectively provided in the plurality of battery units;
A battery system comprising: The battery system according to claim 1, wherein the single cell includes a lithium ion secondary battery.

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