JP2017108484A - Power storage state adjustment device, battery pack, load system and power storage state adjustment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage state adjustment device capable of shortening the time required for cell balance processing.SOLUTION: The present invention relates to a power storage state adjustment device 100 configured to adjust a power storage state during charge/discharge of a battery pack 10 in which multiple storage batteries B1-B4 are connected in series. The power storage state adjustment device comprises: multiple current adders 21a-21d that are connected in parallel to the multiple storage batteries; and multiple current subtracters 22a-22d that are connected in parallel with the multiple storage batteries. The power storage state adjustment device further comprises: multiple voltage sensors VS1-VS4 for measuring voltages of the multiple storage batteries; and a control circuit 40 for controlling the multiple current adders and the multiple current subtracters in such a manner that the voltages of the multiple storage batteries are balanced during the charge/discharge of the battery pack, based on measurements of the multiple voltage sensors.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a storage state adjustment device, a battery pack, a load system, and a storage state adjustment method.

  In recent years, technology for charging / discharging an assembled battery in which a plurality of storage batteries are connected in series has been actively developed.

  For example, Patent Literature 1 discloses a cell balance process for adjusting a charging current and a discharging current in order to make the cell voltage (battery voltage) of each storage battery the same (cell balance) during charging and discharging of the assembled battery. .

  However, the technique disclosed in Patent Document 1 has room for improvement with respect to shortening the time required for cell balance processing.

  The present invention is a storage state adjustment device for adjusting a storage state during charging / discharging of an assembled battery in which a plurality of storage batteries are connected in series, and a plurality of current adders connected in parallel to each of the plurality of storage batteries; And a plurality of current subtractors connected in parallel to each of the plurality of storage batteries.

  According to the present invention, the time required for the cell balance process can be shortened.

It is a figure which shows schematic structure of the battery pack of one Embodiment. It is a circuit diagram of the assembled battery, current addition circuit, and current subtraction circuit in the battery pack. It is a figure which shows the time change of the cell voltage of storage battery B1-B4 at the time of charging / discharging. It is a flowchart for demonstrating an electrical storage state adjustment process. It is a circuit diagram of the assembled battery, the current addition circuit, and the current subtraction circuit of Modification 1. It is a circuit diagram of the assembled battery, the current addition circuit, and the current subtraction circuit of Modification 2. FIG. 11 is a circuit diagram of an assembled battery, a current addition circuit, and a current subtraction circuit according to Modification 3.

  Below, the battery pack 1 of one Embodiment of this invention is demonstrated with reference to drawings.

  As shown in FIG. 1, the battery pack 1 includes an assembled battery 10, a current addition circuit 20A, a current subtraction circuit 20B, a voltage detection means 30, a control circuit 40, a charger / load connection detection unit 50, and the like.

  The assembled battery 10 includes a plurality of (for example, four) storage batteries B1 to B4 (also called secondary batteries or batteries) connected in series. The positive electrode of the storage battery B1 is connected to the P + terminal, and the negative electrode of the storage battery B4 is connected to the P− terminal. The P + terminal and the P terminal are connected to a charger and a load.

  The current adder circuit 20A includes a plurality of (for example, four) current adders 21a to 21d connected in parallel to each of the plurality of (for example, four) storage batteries B1 to B4.

  As shown in FIG. 2, each current adder includes a plurality (for example, two) of variable constant current circuits 21-1 and 21-2. In FIG. 2, the two variable constant current circuits 21-1 and 21-2 are illustrated as if they are connected in parallel only to the storage battery B <b> 1, but actually, each of the storage batteries B <b> 2 to B <b> 4 is also illustrated. Connected in parallel. Here, only two variable constant current circuits 21-1 and 21-2 of the current adder 20a are representatively illustrated.

  The variable constant current circuit 21-1 includes a flyback transformer FBT including a primary side coil L1, a secondary side coil L2, and a diode D, a drain connected to one end of the primary side coil L1, and a source connected to one end of the resistor R1. Transistor TR1 (for example, FET), an output terminal is connected to the gate of the transistor TR1, a positive input terminal is connected to the positive electrode of the variable current source AE1, and a negative input terminal is connected to the source of the transistor TR1. And an operational amplifier OA1.

  The variable constant current circuit 21-2 includes a current mirror circuit CMC including two transistors TR2 and TR3 (for example, FETs) whose gates are connected to each other, a drain connected to the source of the transistor TR2, and a source connected to one end of the resistor R2. The connected transistor TR4 (eg, FET), the output terminal is connected to the gate of the transistor TR4, the positive input terminal is connected to the positive electrode of the variable current source AE2, and the negative input terminal is connected to the source of the transistor TR4. Operational amplifier OA.

  Note that FETs (eg, MOSFETs or junction FETs) are used as the transistors TR1 to TR4, but bipolar transistors may be used.

  The current subtracting circuit 20B includes a plurality of (for example, four) current subtractors 22a to 22d connected in parallel to the plurality of storage batteries B1 to B4.

  Each current subtractor includes a resistor R and a switch SW for connecting and blocking both ends of the storage battery corresponding to both ends of the resistor R. Here, a relay is used as the switch SW, but a transistor may be used.

  The voltage detection circuit 30 includes a plurality (for example, four) of voltage sensors VS1 to VS4 that measure cell voltages (battery voltages) of the storage batteries B1 to B4.

  The control circuit 40 controls the plurality of current adders 21a to 21d and the plurality of current subtractors 22a to 22d based on outputs (measured values) of the plurality of voltage sensors VS1 to VS4.

  More specifically, as shown in FIG. 3, the control circuit 40 measures each voltage sensor at a predetermined time t <b> 1 during charging / discharging of the assembled battery 10 (the charging start time of the assembled battery 10 is set to time 0). And a preset difference ΔV of the balance voltage BV, and based on the difference ΔV, a current addition / subtraction value and a current addition / subtraction time for the corresponding storage battery are calculated and output to the corresponding current adder or current subtractor.

  Specifically, when the difference ΔV in the voltage sensor corresponding to a certain storage battery is positive, the control circuit 40 calculates the difference ΔV by subtracting the current subtraction value (−ΔI / Δt) × the current subtraction time (t2−t1) ×. It converts into the resistance value of resistance R, and supplies a current subtraction value to the current subtracter corresponding to the storage battery during the current subtraction time. That is, the control circuit 40 performs current subtraction with respect to the storage battery by the current subtraction value by connecting the both poles of the storage battery and both ends of the resistor R by turning on the switch SW from time t1 and turning on the switch SW.

  On the other hand, when the difference ΔV in the voltage sensor corresponding to a certain storage battery is negative, the control circuit 40 calculates a current addition value (+ ΔI / Δt) with respect to the difference ΔV and supplies the current adder corresponding to the storage battery to the current adder. Output during subtraction time. In other words, the control circuit 40 uses the current addition value as the pulse amplitude, the current subtraction time as the pulse width, the time t1 as the rise timing, and the pulse signal having the time t2 as the fall timing as the drive signal as two drive constant currents. Output to the variable current sources AE1 and AE2 of the circuits 21-1 and 21-2. At this time, the variable current sources AE1 and AE2 are turned on during the current subtraction time, and current can be added to the storage battery using the current addition value.

  As described above, since the current subtraction value by the resistor R of the current subtractor is constant, the current addition time by the variable constant current circuit of the current adder is matched with the current subtraction time (t2-t1) by the resistor R. The cell voltages of the plurality of storage batteries can be substantially matched with the balance voltage BV at the same time t2.

  As can be seen from the above description, the control circuit 40 includes a plurality of current adders 21 a to 21 d and a plurality of current subtractors so that the cell voltages of the plurality of storage batteries are balanced (substantially coincident) during charging / discharging of the assembled battery 10. 22a to 22d are controlled.

  In addition, the balance time t2 in which the cell voltage of a some storage battery balances becomes late, so that the balance voltage BV is large.

  Here, a detection signal or a non-detection signal from the charger / load connection detection unit 50 is transmitted to the control circuit 40. The charger / load connection detection unit 50 detects whether or not a charger or a load is connected to the battery pack 1 based on a change in voltage between the P + terminal and the P− terminal. That is, when the voltage change between the P + terminal and the P− terminal is large, it is possible to detect whether or not the charger is connected, and when it is small, it is possible to detect whether or not the load is connected.

  Next, a storage state adjustment process (also referred to as a cell balance process) using the storage state adjustment apparatus 100 of the present embodiment will be described with reference to FIG. The flowchart of FIG. 4 is based on the processing algorithm of the control circuit 40. This storage state adjustment process is started when a charger or a load (device) is connected to the battery pack 1. Here, the flow when connected to a charger (during charging) will be described as an example, but the same flow is established when connected to a load (during discharging). Note that the device as a load includes any device that consumes electric power (energy) stored in the assembled battery 10.

  In the first step S1, the cell voltages V1 to V4 (see FIG. 3) of the four storage batteries BAT1 to BAT4 at time t1 (the time when charging is started is time 0) are acquired.

  In the next step S2, differences ΔV1 to ΔV4 between the obtained cell voltages V1 to V4 of the four storage batteries and the balance voltage BV are calculated.

  In the next step S3, current addition / subtraction values and current addition / subtraction times (t2-t1) for the four storage batteries are calculated based on the calculated ΔV1 to ΔV4.

  In the next step S4, based on the current addition / subtraction value (+ ΔI / Δt or −ΔI / Δt) and the current subtraction time (t2-t1) for each storage battery, the current adder or current subtracter corresponding to the storage battery is controlled. . When step S4 is executed, the flow ends.

  The storage state adjustment device 100 of the present embodiment described above is a storage state adjustment device that adjusts the storage state during charging / discharging of the battery pack 10 in which a plurality of storage batteries BAT1 to BAT4 are connected in series, and includes a plurality of storage batteries. A plurality of current adders 21a to 21d connected in parallel to each other and a plurality of current subtractors 22a to 22d connected in parallel to each of the plurality of storage batteries are provided.

  In this case, since the current can be individually added to or subtracted from the plurality of storage batteries, the voltages (cell voltages) of the plurality of storage batteries can be balanced at high speed.

  As a result, the time required for the cell balance process can be shortened.

  In addition, the storage state adjustment device 100 is charging / discharging the assembled battery 10 based on a plurality of (for example, four) voltage sensors VS1 to VS4 that measure the voltages of the plurality of storage batteries and the measurement values of the plurality of voltage sensors. It is preferable to further include a control circuit 40 that controls the plurality of current adders and the plurality of current subtractors so that the voltages of the plurality of storage batteries are balanced.

  In this case, the cell balance process can be performed in any short time zone during charging and discharging of the assembled battery 10.

  In addition, during charging / discharging of the battery pack 10, the control circuit 40 turns on only the corresponding current adder for a part of the plurality of storage batteries and handles the other part of the plurality of storage batteries. It is preferable to turn on only the current subtractor.

  In this case, the current addition for a part of the plurality of storage batteries and the current subtraction for the other part of the plurality of storage batteries can be performed in parallel, and the time required for the cell balance process can be reliably shortened.

  Moreover, the voltage of a part of the plurality of storage batteries is lower than a predetermined voltage (for example, the balance voltage BV) between the maximum voltage and the minimum voltage among the voltages of the plurality of storage batteries, and the other part of the voltages of the plurality of storage batteries is When the voltage exceeds a predetermined voltage (for example, the balance voltage BV), the time required for the cell balance process can be more reliably reduced.

  Further, when each current adder includes two variable constant current circuits 21-1 and 21-2, current addition can be performed at a higher speed for the corresponding storage battery.

  In short, the current adder preferably includes at least one variable constant current circuit. The current subtractor may include at least one variable constant current circuit.

  Moreover, since the battery pack 1 of this embodiment is provided with the assembled battery 10 in which the some storage battery was connected in series, and the electrical storage state adjustment apparatus 100 which adjusts the electrical storage state of this assembled battery 10, charging / discharging Can be performed stably at high speed.

  Moreover, according to the load system provided with the battery pack 1, the charger connected to the battery pack 1, and the load connected to the battery pack 1, a load system capable of constantly ensuring stable power can be provided.

  Further, from the first viewpoint, the power storage state adjustment method of the present embodiment adjusts the power storage state during charging / discharging of the assembled battery 10 in which a plurality of (for example, four) storage batteries BAT1 to BAT4 are connected in series. A state adjustment method, a step of connecting a plurality of storage batteries and a plurality of current adders in parallel, a step of connecting a plurality of storage batteries and a plurality of current subtractors in parallel, and measuring a voltage of each of the plurality of storage batteries And a step of controlling the plurality of current adders and the plurality of current subtractors based on the measurement result in the step of measuring.

  In this case, since the current can be individually added to or subtracted from the plurality of storage batteries, the voltages (cell voltages) of the plurality of storage batteries can be balanced at high speed.

  As a result, the time required for the cell balance process can be shortened.

  In the controlling step, it is preferable to control the plurality of current adders and the plurality of current subtractors so that the voltages of the plurality of storage batteries are balanced.

  In this case, the cell balance process can be performed in any short time zone during charging and discharging of the assembled battery 10.

  Further, in the control step, during charging / discharging of the assembled battery 10, only the current adder corresponding to a part of the plurality of storage batteries is turned ON and the other part of the plurality of storage batteries is supported. It is preferable to turn on only the current subtractor.

  In this case, the current addition for a part of the plurality of storage batteries and the current subtraction for the other part of the plurality of storage batteries can be performed in parallel, and the time required for the cell balance process can be reliably shortened.

  Further, from the second viewpoint, the power storage state adjustment method according to the present embodiment adjusts the power storage state during charging / discharging of the assembled battery 10 in which a plurality of (for example, four) storage batteries BAT1 to BAT4 are connected in series. A state adjustment method that adds a current to a part of a plurality of storage batteries and measures a voltage of each of the plurality of storage batteries and a measurement result in the measurement step. Subtracting the current from a portion of

  In this case, since currents can be individually added to or subtracted from the plurality of storage batteries, the voltages (cell voltages) of the plurality of storage batteries can be balanced (matched) at high speed.

  Moreover, the voltage of a part of the plurality of storage batteries is lower than a predetermined voltage (for example, the balance voltage BV) between the maximum voltage and the minimum voltage among the voltages of the plurality of storage batteries, and the other part of the voltages of the plurality of storage batteries is When the voltage exceeds a predetermined voltage (for example, the balance voltage BV), the time required for the cell balance process can be more reliably reduced.

  In the above embodiment, the current adder includes the two variable constant current circuits 21-1 and 21-2. However, the current adder has a variable constant current as in the current adder of Modification 1 shown in FIG. Only the circuit 21-2 may be provided, or only the variable constant current circuit 21-1 may be provided as in the current adder shown in FIG. 6, or the current adder shown in FIG. As described above, only the variable constant current circuit 21-2 ′ obtained by simplifying the variable constant current circuit 21-2 may be provided.

  In the above-described embodiment, each current subtractor includes a single resistor. However, at least one current subtractor may include, for example, a resistor circuit or a variable resistor that can switch a resistance value.

  Moreover, in the said embodiment, the number of the storage batteries which comprise an assembled battery, the number of the current adders and current subtractors connected in parallel with each storage battery, and the number of voltage sensors can be changed suitably.

  Below, the thought process which the inventors came to invent the said embodiment and each modification is demonstrated.

  2. Description of the Related Art Conventionally, a cell balance method that improves the charging efficiency of a power storage module (battery pack) including an assembled battery in which a plurality of storage battery cells are connected in series is known.

  However, as an important need for a storage battery, there is a drawback in that the energy stored in the storage module cannot be used efficiently due to variations in capacity between storage battery cells.

  As a countermeasure for this problem, there is a method of controlling a cell balance current between a plurality of storage battery cells of a power storage module.

  For example, Japanese Patent No. 4931354 discloses a circuit that balances cells for the purpose of setting the cell voltages of a plurality of storage batteries connected in series in a power storage module to the same voltage during charging.

  Patent Document 1 discloses a cell balance method that adjusts a charging current for the purpose of setting the cell voltages of a plurality of storage batteries connected in series in a power storage module to the same voltage during charging.

  Japanese Patent Laid-Open No. 2013-223320 discloses a cell balance method for adjusting the charging current in order to reduce the cell voltage of a plurality of storage batteries connected in series in a power storage module by using a transformer. It is disclosed.

  Japanese Patent Application Laid-Open No. 2005-151720 discloses a cell balance method for adjusting a charging current for the purpose of performing cell balancing of cell voltages of a plurality of storage batteries connected in series in a power storage module by using a constant current circuit. Is disclosed.

  However, these methods for controlling the cell balance current have room for improvement with respect to rapid cell balance.

  By the way, it is necessary to flow a larger current than usual during high-speed charging / discharging. For example, in order to fully charge a storage battery in 5 minutes, it is necessary to charge / discharge at a rate 12 times as fast as charging a storage battery over 1 hour. The current value needs to flow 12 times as much current, and in order to complete the cell balance rapidly, it is necessary to individually control the individual cell currents constituting the power storage module with a simple circuit.

  Therefore, the inventor has come up with the above-described embodiment and each modification for the purpose of cell balancing at low cost and at high speed.

  DESCRIPTION OF SYMBOLS 1 ... Battery pack, 10 ... Assembly battery, 21a-21d ... Current adder, 22a-22d ... Current subtractor, 40 ... Control circuit, 100 ... Power storage state adjustment apparatus, VS1-VS4 ... Voltage sensor, BAT1-BAT4 ... Storage battery , R: Resistance (resistor).

JP, 2015-1540606, A

Claims (13)

A storage state adjusting device that adjusts a storage state during charging / discharging of a battery pack in which a plurality of storage batteries are connected in series,
A plurality of current adders connected in parallel to each of the plurality of storage batteries;
And a plurality of current subtractors connected in parallel to each of the plurality of storage batteries. A plurality of voltage sensors for measuring the voltage of each of the plurality of storage batteries;
A control circuit for controlling the plurality of current adders and the plurality of current subtractors so that the voltages of the plurality of storage batteries are balanced during charging / discharging of the assembled battery based on measurement values of the plurality of voltage sensors; The power storage state adjusting device according to claim 1, further comprising:   During the charging / discharging of the assembled battery, the control circuit turns on only the current adder corresponding to a part of the plurality of storage batteries and the other part of the plurality of storage batteries. The power storage state adjusting device according to claim 2, wherein only the corresponding current subtractor is turned on. The voltage of a part of the plurality of storage batteries is lower than a predetermined voltage between the maximum voltage and the minimum voltage among the voltages of the plurality of storage batteries,
The other part of the plurality of storage batteries has a voltage that exceeds the predetermined voltage.   The at least one of the said current adder and the said current subtractor contains an at least 1 variable constant current circuit, The electrical storage state adjustment apparatus as described in any one of Claims 1-4 characterized by the above-mentioned.   The said current subtractor contains a resistor, The electrical storage state adjustment apparatus as described in any one of Claims 1-5 characterized by the above-mentioned. An assembled battery in which a plurality of storage batteries are connected in series;
A battery pack provided with the electrical storage state adjustment apparatus as described in any one of Claims 1-6 which adjusts the electrical storage state of the said assembled battery. The battery pack according to claim 7;
A charger connected to the battery pack;
And a load connected to the battery pack. A storage state adjustment method for adjusting a storage state during charging / discharging of an assembled battery in which a plurality of storage batteries are connected in series,
Connecting the plurality of storage batteries and a plurality of current adders in parallel;
Connecting the plurality of storage batteries and a plurality of current subtractors in parallel;
Measuring a voltage of each of the plurality of storage batteries;
And a step of controlling the plurality of current adders and the plurality of current subtractors based on a measurement result in the measuring step.   The power storage state adjustment method according to claim 9, wherein in the controlling step, the plurality of current adders and the plurality of current subtractors are controlled so that voltages of the plurality of storage batteries are balanced.   In the step of controlling, during charging / discharging of the assembled battery, only the current adder corresponding to a part of the plurality of storage batteries is turned ON and the other part of the plurality of storage batteries is supported. The power storage state adjustment method according to claim 9 or 10, wherein only the current subtractor to be turned on is turned on. A storage state adjustment method for adjusting a storage state during charging / discharging of an assembled battery in which a plurality of storage batteries are connected in series,
Measuring a voltage of each of the plurality of storage batteries;
A step of adding a current to a part of the plurality of storage batteries and subtracting a current from the other part of the plurality of storage batteries based on a measurement result in the measuring step. Adjustment method. The voltage of a part of the plurality of storage batteries is lower than a predetermined voltage between the maximum voltage and the minimum voltage among the voltages of the plurality of storage batteries,
The other part of the plurality of storage batteries has a voltage exceeding the predetermined voltage, and the state of charge adjustment method according to claim 11 or 12.

Images