Battery characteristic measurement device

Abstract

To provide a battery characteristic measurement device that can measure battery characteristics in a power supply circuit including a plurality of batteries that can be connected in series while suppressing manufacturing costs.SOLUTION: A battery characteristic measurement device 100 for measuring characteristics of batteries 20 in a power supply circuit 200 which includes the plurality of batteries 20, selects the batteries from the plurality of batteries 20 and can connect the selected batteries 20 in series, comprises an AC current generator 10, and measures the AC impedance of the power supply circuit 200 from the output voltage of the power supply circuit 200 in a state where the AC current is applied from the AC current generator 10 to the selected batteries 20 while switching the batteries 20 selected in the power supply circuit 200.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a battery characteristic measuring device. [Background technology]

[0002] A battery control device is disclosed that controls a power storage system having multiple storage batteries connected in series and a bypass circuit that bypasses each of the storage batteries, and that executes a first process that reduces the difference in the remaining charge amounts until charging is complete among the multiple storage batteries by preferentially bypassing the storage batteries that have a lower remaining charge amount until charging is complete compared to the other storage batteries using the bypass circuit, and a second process that completes the charging of the multiple storage batteries after the first process.

[0003] Also disclosed is a charging control device including an AC power source, a battery module composed of n battery cells connected in series to the AC power source, n LC circuits connected in parallel to the n battery cells in a one-to-one relationship and having mutually different resonance frequencies f01 to f0n, and a charging control unit that detects the cell voltages of the battery cells and adjusts the frequency of the AC current from the AC power source based on the detected cell voltages (Patent Document 2). Here, the LC circuit has a combined resistance value determined so that the resonance frequencies f01 to f0n satisfy a predetermined formula, and the charging control unit identifies at least one battery cell including a battery cell having the highest cell voltage from the cell voltages, determines the resonance frequency of the LC circuit corresponding to the identified battery cell, and controls so that an AC current having the same frequency as the determined resonance frequency is output from the AC power source.

[0004] Patent document 3 discloses a battery monitoring device that includes a monitoring current supply unit that supplies current to some or all of the battery cells to be measured in a battery pack and to a detection resistor connected in series to the battery cells to be measured, an application unit that simultaneously applies to the monitoring current supply unit a signal generated by a drive signal generation unit by superimposing multiple different single-frequency signals, and a plurality of lock-in detection units provided for each of the multiple single frequencies, which feed back and input signals generated in the detection resistor and the battery cell to be measured when applied from the application unit to the monitoring current supply unit, and which input each of the multiple single-frequency signals generated by the drive signal generation unit and mix them using a mixer to perform lock-in detection, and a measurement unit that measures the impedance at each of the multiple single frequencies based on the detection results of the multiple lock-in detection units. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2022-141453 A [Patent Document 2] JP 2019-009902 A [Patent Document 3] JP 2023-031578 A Summary of the Invention [Problem to be solved by the invention]

[0006] In order to measure the individual impedance and voltage of multiple batteries (battery cells) that can be connected in series, it is necessary to provide a measuring device such as a sensor for each battery (battery cell). Therefore, there is a technical problem that the manufacturing cost of the measuring device increases as the number of batteries (battery cells) that can be directly connected increases. [Means for solving the problem]

[0007] One aspect of the present invention is a battery characteristic measuring device that includes a plurality of batteries, selects one of the plurality of batteries, and measures the characteristics of the battery for a power supply circuit to which the selected battery can be connected in series, the battery characteristic measuring device including an AC current generator, and switches the battery selected in the power supply circuit, measuring the AC impedance of the power supply circuit from the output voltage of the power supply circuit when an AC current is flowing from the AC current generator to the selected battery.

[0008] Here, it is preferable to sequentially switch the batteries selected in the power supply circuit and measure the AC impedance of the power supply circuit from the output voltage of the power supply circuit when AC current is flowing from the AC current generator to the selected battery.

[0009] It is also preferable that the AC current generator includes an LCR resonant circuit, passes an AC current having a damped oscillatory waveform through the power supply circuit, and measures the real impedance of the power supply circuit.

[0010] It is also preferable to measure the battery voltage of each of the batteries individually. Effect of the Invention

[0011] According to the present invention, it is possible to provide a battery characteristic measuring device that makes it possible to measure the battery characteristics of a power supply circuit including a plurality of batteries that can be connected in series while suppressing manufacturing costs. [Brief description of the drawings]

[0012] [Figure 1] 1 is a diagram showing a configuration of a battery characteristic measuring device in an embodiment of the present invention. [Diagram 2] 3A to 3C are diagrams illustrating various states of a power supply circuit according to an embodiment of the present invention. [Diagram 3] FIG. 11 is a diagram showing a configuration of another example of a battery characteristic measuring device in an embodiment of the present invention. [Figure 4]4 is a diagram showing an example of a damped oscillation waveform output from a battery characteristic measuring device in an embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] 1, a battery characteristic measuring device 100 in an embodiment of the present invention includes an AC current generating device 10, a voltage measuring device 12, and a current measuring device 14. The battery characteristic measuring device 100 is connected to a power supply circuit 200 when in use.

[0014] The power supply circuit 200 includes a plurality of batteries 20 (20-1, 20-2, . . . , 20-n) that can be connected in series with each other. The batteries 20 can be rechargeable secondary batteries (storage batteries), such as lithium ion batteries.

[0015] A first switch SWa (SWa1, Swa2, . . . , SWan) is connected in series to each of the batteries 20 (20-1, 20-2, . . . , 20-n). In addition, a second switch SWb (SWb1, Swb2, . . . , SWbn) is connected in parallel to each of the series-connected circuits of the batteries 20 (20-1, 20-2, . . . , 20-n) and the first switch SWa (SWa1, Swa2, . . . , SWan).

[0016] The state of each battery 20 can be switched by switching the first switch SWa and the second switch SWb. As shown in FIG. 2, for the n-th battery 20-n, the first switch SWan is turned on and the second switch SWbn is turned off, so that the battery 20-n is in a battery output state in which it is connected in series to the positive output terminal T1 and the negative output terminal T2. This state is also a measurement state when performing impedance measurement, which will be described later. In addition, the first switch SWan is turned off and the second switch SWbn is turned on, so that the battery 20-n is in a pass-through state in which it is not connected to the positive output terminal T1 and the negative output terminal T2. Note that a state in which the first switch SWan and the second switch SWbn are turned off at the same time, and a state in which the first switch SWan and the second switch SWbn are turned on at the same time are not permitted. The same applies to the other batteries 20.

[0017] In this way, multiple batteries 20 in the battery output state can be connected in series and discharged or charged from the positive output terminal T1 and the negative output terminal T2 by switching the first switch SWa and the second switch SWb provided in each battery 20. At this time, the battery 20 in the pass-through state is not involved in the discharge or charging from the positive output terminal T1 and the negative output terminal T2.

[0018] The battery characteristic measuring device 100 is connected to both ends of the power supply circuit 200 which constitutes a series module of the battery 20 as described above. The AC current generating device 10 included in the power supply circuit 200 is connected in parallel to the power supply circuit 200. In addition, the voltage measuring device 12 included in the power supply circuit 200 is connected in parallel to the power supply circuit 200. The current measuring device 14 measures the AC current Iac supplied from the AC current generating device 10 to the power supply circuit 200.

[0019] In this embodiment, one voltage measuring device 12 is provided for the entire power supply circuit 200, but it may also be configured such that one voltage measuring device 12 is provided for each group of multiple batteries 20, or for each battery 20.

[0020] In this configuration, when an AC current is applied from the AC current generator 10 to the power supply circuit 200, the current flows only through the battery 20 in the battery output state. Then, the voltage measurement device 12 measures the integrated value of the voltage for the current flowing through the battery in the battery output state.

[0021] As an embodiment, an example in which four battery cells are connected in series to form a module in the power supply circuit 200 will be shown. n The battery output state is indicated as 1, and the pass-through state is indicated as 0. The battery state BST of the four battery cells is expressed by equation (1) using a matrix.

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[0022] Here, three of the four batteries 20 are sequentially switched to the battery output state. That is, the batteries 20 to be in the pass-through state are controlled in order from the first battery 20-1, to the second battery 20-2, to the third battery 20-3, to the fourth battery 20-4. At this time, the battery state matrix BST is expressed by the formula (2).

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[0023] Here, the output voltage V output from the battery 20 in the battery output state to the positive output terminal T1 and the negative output terminal T2 is po is the voltage V of BST and each battery 20 batn It is expressed by the formula (3) using

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[0024] Output voltage V po is expressed by the formula (3), and when an AC current Iac is applied, an AC voltage V acn Therefore, the voltage V measured by the voltage measuring device 12 mes is expressed by equation (4).

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[0025] Here, the DC component, voltage V batn can be separated using a DC cut filter or the like, so the AC component of equation (4) can be expressed by equation (5).

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[0026] The impedance equation is obtained by dividing the equation (5) by the current Iac. Therefore, the impedance of each battery 20 can be obtained by solving the simultaneous equations obtained by dividing the equation (5) by the current Iac.

[0027] 3 shows the configuration of a battery characteristic measuring device 102. The battery characteristic measuring device 102 includes an LCR resonant circuit, instead of the AC current generating device 10, that includes an inductor Lr, a resistor Rr, and a capacitor Cr.

[0028] The inductor Lr and the resistor Rr are connected in series together with the switch SWr. The resistor Rr is connected in parallel with the capacitor Cr. The inductor Lr is provided with a secondary inductor Lsec that is magnetically coupled with the inductor Lr via a mutual inductance M.

[0029] In such an LCR resonant circuit, by turning on the switch SWr, a voltage V having a damped oscillation waveform as shown in FIG. res and can be applied to the power supply circuit 200. res The damped oscillation waveform of 1 The voltage V of peak n1 res (t 1 ), time t 2 The peak voltage of n2 is V res (t 2 ),..., time t n Peak n at V res (t n ) ··· is a decaying waveform.

[0030] The resonant circuit included in the battery characteristic measuring device 102 is not limited to the configuration shown in FIG. 3, and may be a resonant circuit having a damped oscillation waveform voltage V res Any configuration that generates the above may be used.

[0031] Here, the resonant voltage Vres output to the inductor Lsec magnetically coupled to the inductor Lr is expressed by the formula (6). bat indicates the real impedance of the entire battery 20 currently in the battery output state and connected in series.

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[0032] The nth resonance point V res (t n ) is expressed by equation (7).

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[0033] For any peak n=n1, n2 (n1>n2) of the damped oscillation waveform, the resistance R bat is expressed by equation (8).

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[0034] In addition, the output voltage V of the entire series-connected batteries 20 that are currently in the battery output state is bat is expressed by equation (9).

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[0035] Therefore, the batteries 20 in the pass-through state are controlled in order from the first battery 20-1, the second battery 20-2, the third battery 20-3, and the fourth battery 20-4, while the resistance R bat and voltage V batBy measuring the impedances and solving the simultaneous equations, the real impedance R of the internal impedance of each battery 20 is calculated. batn and the output voltage V batn can be calculated.

[0036] [Configuration of the present invention] [Configuration 1] A battery characteristic measuring device including a plurality of batteries, selecting one of the plurality of batteries, and measuring characteristics of the battery for a power supply circuit to which the selected battery can be connected in series, comprising: Equipped with an alternating current generator, A battery characteristic measuring device characterized by: switching the battery selected in the power supply circuit; and measuring the AC impedance of the power supply circuit from the output voltage of the power supply circuit in a state in which an AC current is flowing from the AC current generator to the selected battery. [Configuration 2] The battery characteristic measuring device according to configuration 1, A battery characteristic measuring device characterized by: switching the batteries selected in the power supply circuit in sequence; and measuring the AC impedance of the power supply circuit from the output voltage of the power supply circuit when an AC current is flowing from the AC current generator to the selected battery. [Configuration 3] The battery characteristic measuring device according to configuration 1 or 2, The battery characteristic measuring device is characterized in that the AC current generating device includes an LCR resonant circuit, and flows an AC current having a damped oscillatory waveform through the power supply circuit, thereby measuring the real impedance of the power supply circuit. [Configuration 4] The battery characteristic measuring device according to any one of configurations 1 to 3, A battery characteristic measuring device which measures the battery voltage of each of the batteries individually. [Explanation of symbols]

[0037] 10 AC current generator, 12 voltage measuring device, 14 current measuring device, 20 battery, 100 battery characteristic measuring device, 102 battery characteristic measuring device, 200 power supply circuit.

Claims

1. A battery characteristic measuring device including a plurality of batteries, selecting one of the plurality of batteries, and measuring characteristics of the battery for a power supply circuit to which the selected battery can be connected in series, comprising: Equipped with an alternating current generator, A battery characteristic measuring device characterized by: switching the battery selected in the power supply circuit; and measuring the AC impedance of the power supply circuit from the output voltage of the power supply circuit in a state in which an AC current is flowing from the AC current generator to the selected battery.

2. The battery characteristic measuring device according to claim 1 , A battery characteristic measuring device characterized by: switching the batteries selected in the power supply circuit in sequence; and measuring the AC impedance of the power supply circuit from the output voltage of the power supply circuit when an AC current is flowing from the AC current generator to the selected battery.

3. The battery characteristic measuring device according to claim 1 , The battery characteristic measuring device is characterized in that the AC current generating device includes an LCR resonant circuit, and flows an AC current having a damped oscillatory waveform through the power supply circuit, and measures a real impedance of the power supply circuit.

4. The battery characteristic measuring device according to any one of claims 1 to 3, A battery characteristic measuring device which measures the battery voltage of each of the batteries individually.

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