Battery's internal impedance measuring device

Abstract

To measure battery performance by a simple method.SOLUTION: A control unit 16 causes a damping vibration circuit 12 to generate a damping vibration current by controlling a switch SW. The control unit 16 acquires a damping vibration signal related to the time waveform of the damping vibration current from a signal detector 14 and obtains a real part of impedance of a battery 10. The control unit 16 acquires each sample value at a plurality of sample times obtained by operation of a calibration mode from the time waveform indicated by the damping vibration signal, and obtains the real part of impedance of the battery 10 on the basis of each sample value. The control unit 16 operating in the calibration mode causes the damping vibration circuit 12 to generate the damping vibration current by controlling the switch SW. The control unit 16 acquires a damping vibration signal for calibration related to the time waveform of the damping vibration current and obtains a plurality of positions on the time axis at which the time waveform indicated by the damping vibration signal for calibration becomes maximum, or a plurality of positions on the time axis at which the same becomes minimum, as the plurality of sample times.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an apparatus for measuring the internal impedance of a battery, and more particularly to an apparatus for measuring the real part of the internal impedance of a battery. [Background technology]

[0002] Electric vehicles, such as hybrid vehicles and electric vehicles, that run on battery power are widely used. For electric vehicles, charging devices connected to a power supply network provided by a power supply company or the like are provided at service stations, parking lots, etc. The batteries of the electric vehicles are charged by the charging devices.

[0003] Furthermore, battery-powered electric devices such as forklifts and transport vehicles are used in factories, offices, event venues, etc. To use multiple electric devices in various locations within the premises of a factory, office, etc., a charging system has been developed in which a charging device is connected to key points in a locally constructed power supply network.

[0004] Regarding electric vehicles and charging systems, a technology is known for controlling a plurality of charging devices connected to a power supply network. In this technology, a control device acquires information indicating the charging state of a battery from each charging device, and the control device controls each charging device according to the charging state of the battery in each charging device. Patent Document 1 describes a distributed power system using such a technology. This distributed power system includes a plurality of power conversion units (charging devices) and a control unit (control device) that controls each power conversion unit. A battery is connected to each power conversion unit. The control unit acquires the SOC (State Of Charge) of the battery from each of the plurality of power conversion units, and controls charging and discharging of each power conversion unit according to the SOC. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-116428 A [Patent Document 2] JP 2018-179652 A [Patent Document 3] JP 2001-235525 A Summary of the Invention [Problem to be solved by the invention]

[0006] Generally, the performance of a battery deteriorates with use. Therefore, a system is conceivable in which a charging device measures the degree of deterioration of a battery, and a control device collects information on the degree of deterioration of the battery measured by each charging device. For example, as described in Patent Documents 2 and 3, the degree of deterioration of a battery can be measured by measuring the change in impedance with respect to the change in frequency. However, it is necessary to sweep the frequency of the signal voltage applied to the battery over a wide range, which can make the measurement difficult.

[0007] An object of the present invention is to measure the performance of a battery in a simple manner. [Means for solving the problem]

[0008] The battery internal impedance measuring device according to the present invention comprises a damped oscillation circuit connected to a battery to be measured, a drive circuit for electrically oscillating the damped oscillation circuit, and a control unit, the control unit operates in a measurement mode or a calibration mode, the measurement mode is a mode in which the drive circuit is controlled to electrically oscillate the damped oscillation circuit, a damped oscillation signal related to a time waveform of an electrical physical quantity in the damped oscillation circuit is obtained, and a real part of the impedance of the battery is calculated based on the damped oscillation signal, and the calibration mode is a mode in which the drive circuit is controlled to electrically oscillate the damped oscillation circuit, a damped oscillation signal for calibration related to a time waveform of an electrical physical quantity in the damped oscillation circuit is obtained, and a plurality of sample times on a time axis are calculated from the time waveform indicated by the damped oscillation signal for calibration, and the control unit, when operating in the measurement mode, obtains each sample value at a plurality of the sample times from the time waveform indicated by the damped oscillation signal, and calculates the real part of the impedance of the battery based on each sample value.

[0009] Preferably, when operating in the calibration mode, the control unit determines, as the multiple sample times, multiple positions on the time axis where the time waveform indicated by the calibration damped oscillation signal is at a maximum, or multiple positions on the time axis where the time waveform indicated by the calibration damped oscillation signal is at a minimum.

[0010] Preferably, the drive circuit includes a switch connected to the damped oscillation circuit, and the damped oscillation circuit oscillates electrically when the switch is turned on in a pulsating manner under the control of the control unit.

[0011] Preferably, the damped oscillation circuit includes a resonant inductor and a capacitive element connected in series, and the electrical physical quantity is a current flowing through the resonant inductor and the capacitive element.

[0012] Preferably, the battery, the resonant inductor and the capacitive element are connected in series to form a resonant circuit.

[0013] Desirably, the device includes a coupled inductor coupled to the resonant inductor and an electronic circuit connected to the coupled inductor, the electronic circuit generating the damped oscillation signal based on a voltage appearing in the coupled inductor, and the control unit acquiring sample values ​​at three or more of the sample times from the damped oscillation signal and compensating for DC offset components contained in the damped oscillation signal based on the sample values. Effect of the Invention

[0014] According to the present invention, the performance of a battery can be measured in a simple manner. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram showing a configuration of a battery internal impedance measuring device. [Diagram 2] FIG. 4 is a diagram showing an outline of a time waveform of a damped oscillation signal. [Diagram 3] FIG. 2 is a diagram conceptually showing a first processing example for determining each sample time. [Figure 4] FIG. 13 is a diagram conceptually showing a second processing example for determining each sample time. [Diagram 5] 13 is a flowchart of a process executed by a control unit. [Figure 6A] FIG. 13 is a diagram showing experimental results regarding the real part of impedance. [Figure 6B] FIG. 13 is a diagram showing experimental results regarding the real part of impedance. [Figure 7] FIG. 2 is a diagram illustrating a configuration of a battery management system. [Figure 8] FIG. 1 is a diagram showing a configuration of a battery internal impedance measuring system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The embodiments of the present invention will be described with reference to the drawings. The same components shown in multiple drawings are given the same reference numerals to simplify the description. In the specification and drawings of this application, alphabetical reference numerals indicating circuit elements are also used as reference numerals indicating the element constants of the circuit elements to simplify the description.

[0017] 1 shows the configuration of a battery internal impedance measuring device 100 according to an embodiment of the present invention. The battery internal impedance measuring device 100 includes a damped oscillation circuit 12, a switch SW, a signal detector 14, a control unit 16, and a memory 18. The positive and negative electrodes of a battery 10 to be measured are connected to the damped oscillation circuit 12. The battery 10 is a secondary battery that can be repeatedly charged and discharged, such as a lead-acid battery or a lithium-ion battery.

[0018] The battery internal impedance measuring device 100 passes a damped oscillating current through the battery 10 to be measured, and measures the real part of the internal impedance of the battery 10 based on the value of the damped oscillating current. Here, the real part of the internal impedance of the battery 10 refers to the value of the real part when the internal impedance of the battery 10 is expressed as a complex number. Hereinafter, the real part of the internal impedance of the battery 10 will be simply referred to as the impedance real part of the battery 10. In order to pass a damped oscillating current through the battery 10, the damped oscillation circuit 12 is configured with a resonant circuit P including a resonant inductor L1 and a capacitive element C0.

[0019] The damped oscillation circuit 12 includes a resonance inductor L1, a capacitive element C0, a resistor R0, and a coupled inductor L2. The resonance inductor L1 and the coupled inductor L2 may be formed of a winding. A capacitor, a varicap diode, or the like may be used for the capacitive element C0. The resistor R0 may be a resistive element having a predetermined resistance value, or may be a semiconductor device having a predetermined resistance value. The resistor R0 may be replaced by a loss component included in the capacitive element C0.

[0020] The resonance inductor L1 and the capacitive element C0 are connected in series, and the switch SW is connected in series to the capacitive element C0. The resistor R0 is connected in parallel to the capacitive element C0. The terminal of the resonance inductor L1 opposite to the terminal on the capacitive element C0 side is connected to the positive electrode of the battery 10. The terminal of the switch SW opposite to the capacitive element C0 is connected to the negative electrode of the battery 10. The coupled inductor L2 is coupled to the resonance inductor L1. One end of the coupled inductor L2 is grounded, and the other end is connected to the signal detector 14.

[0021] The resonance inductor L1, the capacitive element C0, and the resistor R0 constitute a resonance circuit P having a loss. The switch SW is controlled to be on or off by the control unit 16. When the switch SW is turned on in a pulsed manner, a damped oscillatory current Ia flows through the battery 10 and the resonance circuit P. Here, the switch SW being turned on in a pulsed manner refers to the switch SW being turned from off to on, remaining on for a predetermined time, and then being turned from on to off.

[0022] As the damped oscillation current Ia flows through the resonance inductor L1, a damped oscillation voltage Ea corresponding to the damped oscillation current Ia appears in the coupled inductor L2. The damped oscillation voltage Ea is output to the signal detector 14. The signal detector 14 adjusts the level of the damped oscillation voltage Ea by amplifying it or the like to generate a damped oscillation signal, and outputs the damped oscillation signal to the control unit 16. The signal detector 14 may convert the damped oscillation voltage Ea into a digital signal to generate the damped oscillation signal as a digital signal. The control unit 16 stores the damped oscillation signal of a predetermined time length, for example, a predetermined j period (j is an integer equal to or greater than 2), in the memory 18, and calculates the impedance real part of the battery 10 based on the damped oscillation signal stored in the memory 18.

[0023] The control unit 16 may include a processor that executes a program. The control unit 16 operates in either a measurement mode or a calibration mode. The measurement mode is an operation mode for determining the real part of the impedance of the battery 10. The calibration mode is an operation mode for determining constants used in the measurement mode.

[0024] The process of the control unit 16 determining the real part of the impedance of the battery 10 through the operation in the measurement mode will be described. Fig. 2 shows an outline of the time waveform of the damped oscillation signal Va. The damped oscillation signal Va is approximately expressed as (Equation 1).

[0025] (Number 1) Va=k·W·Vb·exp[-Rhf·t / (2Lr)]·sin(2πfr·t)

[0026] Here, k is the gain of the signal detector 14, W is the turns ratio of the winding constituting the coupled inductor L2 to the winding constituting the resonant inductor L1, Vb is the output voltage of the battery 10, Rhf is the real part of the impedance of the battery 10, t is the elapsed time from time t0 when the switch SW is turned on in a pulsed manner, Lr is the self-inductance of the resonant inductor L1, and fr is the resonant frequency of the resonant circuit P. (Equation 1) is derived from the fact that the time constant when the maximum values ​​of the damped oscillatory current Ia and the damped oscillatory voltage Ea decay is determined according to the real part of the impedance of the battery 10.

[0027] The control unit 16 stores the damped oscillation signal Va output from the signal detector 14 over j periods in the memory 18. The control unit 16 refers to the damped oscillation signal Va stored in the memory 18, and extracts the values ​​of the damped oscillation signal Va at sample times t1 and t2 after time 0 when the damped oscillation voltage Ea appears in the coupled inductor L2 as sample values ​​Vph1 and Vph2. Here, the sample times t1 and t2 are the times when the damped oscillation signal Va becomes maximum. The control unit 16 determines the sample times t1 and t2 by operating in the calibration mode before operating in the measurement mode.

[0028] The control unit 16 obtains the real part Rhf of the impedance of the battery 10 according to (Equation 2).

[0029] (Number 2) Rhf=ln(Vph2 / Vph1)·ar-br

[0030] Here, ln denotes the natural logarithm. The constants ar and br are determined in advance based on the characteristics of the circuit that is configured with the resonance inductor L1, the coupled inductor L2, the capacitive element C0, and the resistor R0.

[0031] The signal detector 14 may extract a sample value of the damped oscillation voltage Ea at a timing controlled by the control unit 16, convert the sample value into a digital value, and output the digital value to the control unit 16. In this case, the control unit 16 causes the signal detector 14 to output the value of the damped oscillation voltage Ea as a sample value Vph1 at sample time t1. The control unit 16 also causes the signal detector 14 to output the value of the damped oscillation voltage Ea as a sample value Vph2 at sample time t2.

[0032] The control unit 16 may also transmit the sample values ​​Vph1 and Vph2 of the damped oscillation signal to another computer directly or via a telecommunication line such as the Internet. In this case, the other computer calculates the real part of the impedance of the battery 10 based on the sample values ​​Vph1 and Vph2.

[0033] The process of the control unit 16 determining sample times t1 and t2 by the operation in the calibration mode will be described. After the switch SW is turned on in a pulsed manner, the control unit 16 acquires the signal output from the signal detector 14 over i periods as a calibration damped oscillation signal and stores it in the memory 18. Here, i is an integer equal to or greater than 2, and may be the same as the integer j. The control unit 16 refers to the calibration damped oscillation signal stored in the memory 18 and determines two sample times t1 and t2 at which the calibration damped oscillation signal becomes maximum after time t0.

[0034] Fig. 3 conceptually illustrates a first processing example in which the control unit 16 determines sample times t1 and t2. In the example illustrated in Fig. 3, sample time t1 is the time at which the calibration damped vibration signal becomes maximum for the first time after time t0. Sample time t2 is the time at which the calibration damped vibration signal becomes maximum for the fifth time after time t0. Note that sample times t1 and t2 may be any two times at which the calibration damped vibration signal becomes maximum after time t0.

[0035] The control unit 16 searches for the calibration damped oscillation signal stored in the memory 18 to find the first maximum point time after time t0, and obtains the maximum point time as the sample time t1. The control unit 16 also searches for the calibration damped oscillation signal stored in the memory 18 to find the fifth maximum point time after time t0, and obtains the maximum point time as the sample time t2.

[0036] 4 conceptually shows a second processing example in which the control unit 16 determines the sample times t1 and t2. The control unit 16 extracts M1 values ​​at different times from the damped oscillation signal for calibration stored in the memory 18 within a time range including the time at which the first maximum value appears. Here, M1 is an integer equal to or greater than 3. The control unit 16 calculates an interpolation function f(x) for interpolating M1 points on the time waveform of the damped oscillation signal for calibration as f(x)=Σa k x k In other words, the control unit 16 calculates the coefficients a1 to a2 based on the M1 sets of time and the values ​​of the calibration damped vibration signal. M1 Perform the process to obtain the value.

[0037] Similarly, the control unit 16 extracts M2 values ​​at different times within a time range including the time at which the fifth maximum value appears from the damped vibration signal for calibration stored in the memory 18. Here, M2 is an integer equal to or greater than 3. The control unit 16 calculates an interpolation function f(x) for interpolating M2 points on the time waveform of the damped vibration signal for calibration as f(x)=Σa k x kIn other words, the control unit 16 calculates the coefficients a1 to a2 based on the M2 sets of time and the values ​​of the calibration damped vibration signal. M2 As in the first processing example, in the second processing example, the sample times t1 and t2 may be any two times that are maximum after the time t0.

[0038] The signal detector 14 may be an electronic circuit including an amplifier. In this case, the damped oscillation signal output from the signal detector 14 to the control unit 16 may contain a DC offset component. The control unit 16 may obtain the DC offset component by the following process and execute a DC offset compensation process to remove the DC offset component from the damped oscillation signal.

[0039] The control unit 16 executes the operation of the calibration mode in advance, and obtains three sample times t1, t2, and t3 at which the calibration damped oscillation signal is at a maximum. The control unit 16 turns on the switch SW in a pulsed manner to electrically oscillate the damped oscillation circuit 12, and obtains sample values ​​Vph1 to Pph3 of the damped oscillation signal for each of the sample times t1 to t3. The control unit 16 obtains the DC offset component Vofs based on the following (Equation 3).

[0040] (Number 3) Vofs = (Vph1 Vph3 - Vph2 2 ) / (Vph1+Vph2-2Vph2)

[0041] The control unit 16 obtains the real part Rhf of the impedance of the battery 10 from (Equation 4) or (Equation 5).

[0042] (Number 4) Rhf = [(Vph2-Vofs) / (Vph1-Vofs)] (Number 5) Rhf = [(Vph3-Vofs) / (Vph2-Vofs)]

[0043] (Equation 4) and (Equation 5) can be obtained by eliminating ar and br using an equation in which Vph1-Vofs and Vph2-Vofs are substituted for Vph1 and Vph2 in (Equation 2), and an equation in which Vph2-Vofs and Vph3-Vofs are substituted for Vph1 and Vph2, respectively. (Equation 3) can be obtained by solving (Equation 4) and (Equation 5) for Vofs.

[0044] In the above, there has been shown a process of obtaining each sample time based on a local maximum value of the time waveform of the damped oscillation current for calibration flowing through the damped oscillation circuit 12. Each sample time may be obtained based on a local minimum value of the time waveform of the damped oscillation current for calibration flowing through the damped oscillation circuit 12.

[0045] In this way, the control unit 16 operates in either the calibration mode or the measurement mode. The control unit 16 operating in the calibration mode controls the switch SW as a drive circuit to electrically oscillate the damped oscillation circuit 12. Here, electrically oscillating the damped oscillation circuit 12 means fluctuating the value of the voltage or current, which is an electrical physical quantity appearing in the damped oscillation circuit 12, with time. The control unit 16 operating in the calibration mode further acquires a calibration damped oscillation signal related to the time waveform of the current, which is an electrical physical quantity in the damped oscillation circuit 12, and obtains a plurality of sample times on the time axis from the time waveform indicated by the calibration damped oscillation signal. The control unit 16 may operate in the calibration mode in advance before operating in the measurement mode, and obtain a plurality of sample times in advance.

[0046] When operating in the calibration mode, the control unit 16 determines, as multiple sample times, multiple positions on the time axis where the time waveform indicated by the calibration damped oscillation signal is at a maximum, or multiple positions on the time axis where the time waveform indicated by the calibration damped oscillation signal is at a minimum.

[0047] The control unit 16 operating in the measurement mode controls the switch SW as a drive circuit to electrically oscillate the damped oscillation circuit 12. The control unit 16 further acquires a damped oscillation signal relating to the time waveform of the current, which is an electrical physical quantity, in the damped oscillation circuit 12, and calculates the real part of the impedance of the battery 10 based on the damped oscillation signal.

[0048] When operating in the measurement mode, the control unit 16 acquires each sample value at multiple sample times obtained by operation in the calibration mode from the time waveform indicated by the damped oscillation signal, and calculates the real part of the impedance of the battery 10 based on each sample value.

[0049] The battery internal impedance measuring device 100 according to the embodiment of the present invention includes a coupled inductor L2 coupled to the resonance inductor L1, and a signal detector 14 as an electronic circuit connected to the coupled inductor L2. The signal detector 14 generates a damped oscillation signal based on the voltage appearing in the coupled inductor L2, and the control unit 16 may obtain each sample value at three or more sample times from the damped oscillation signal, and compensate for a DC offset component included in the damped oscillation signal based on each sample value.

[0050] The maximum point time at which a maximum value appears in the time waveform of the electrical physical quantity in the damped oscillation circuit 12 varies depending on the relationship between the variation in inductance of the resonance inductor L1, the variation in capacitance of the capacitive element C0, the internal impedance of the battery 10 to be measured, etc. In general, the maximum point time is constant for the same battery, but the maximum point time varies depending on the battery when the battery is different. Therefore, if the sample time t1 and the sample time t2 are constant, the sample times t1 and t2 will not be the times at which the damped oscillation signal becomes maximum due to the variation in the characteristics of the battery 10, and an error will occur in the measurement of the real part of the impedance of the battery 10.

[0051] Therefore, when the battery 10 to be measured is changed, the control unit 16 operates in a calibration mode before operating in the measurement mode, and obtains a plurality of sample times in advance, in the above example, sample times t1 and t2. As a result, even if the battery 10 to be measured is changed, a plurality of maximum values ​​at which the damped oscillation signal becomes maximum can be obtained. Furthermore, even if the battery 10 to be measured is changed, the change in the values ​​of ar and br in (Equation 2) is small. Therefore, according to the battery internal impedance measuring device 100 according to the embodiment of the present invention, even if the battery 10 to be measured is changed, the operation is performed in the calibration mode, and the impedance real part can be obtained with high accuracy.

[0052] FIG. 5 shows a flowchart of the process executed by the control unit 16. However, in this flowchart, the sample times t1 and t2 are simply written as times t1 and t2 for simplicity. The control unit 16 judges whether or not an operation for starting the operation of the calibration mode has been performed in the battery internal impedance measuring device 100 (S101). When the control unit 16 judges that an operation for starting the operation of the calibration mode has not been performed, it judges whether or not the sample times t1 and t2 have been stored in the memory 18 (S102). When the sample times t1 and t2 have been stored in the memory 18, the control unit 16 acquires a damped oscillation signal. That is, the switch SW is turned on in a pulsed manner to generate a damped oscillation current Ia and a damped oscillation voltage Ea in the damped oscillation circuit 12, and the damped oscillation signal is output from the signal detector 14 to the control unit 16. The control unit 16 acquires sample values ​​Vph1 and Vph2 at the sample times t1 and t2 from the damped oscillation signal (S103). The control unit 16 obtains the real part of the impedance of the battery 10 according to (Equation 2) (S104).

[0053] When the control unit 16 determines in step S101 that no operation has been performed to start the calibration mode operation, or when it determines in step S102 that the sample times t1 and t2 have not been stored in the memory 18, it causes the damped oscillation circuit 12 to generate a damped oscillation current Ia and a damped oscillation voltage Ea, and causes the signal detector 14 to output a damped oscillation signal for calibration to the control unit 16. The control unit 16 determines the sample times t1 and t2 from the damped oscillation signal for calibration (S105), and causes the memory 18 to store the sample times t1 and t2 (S106).

[0054] According to the process shown in the flowchart of FIG. 5, when the sample times t1 and t2 are previously obtained and stored in the memory 18, the impedance real part of the battery 10 is obtained without obtaining the sample times t1 and t2 again. On the other hand, when the sample times t1 and t2 are not stored in the memory 18, the operation of the calibration mode is executed (S105 and S106). As a result, the sample times t1 and t2 are obtained according to the characteristics of the battery 10 to be measured and the current measurement conditions (temperature, humidity, etc.), and the impedance real part is obtained based on the sample times t1 and t2. Therefore, the variation of the sample times t1 and t2 caused by the characteristic variation of each battery 10 is suppressed, and the measurement accuracy of the impedance real part is improved. Also, when the sample times t1 and t2 have already been obtained, the same sample times t1 and t2 are subsequently obtained. This reduces the processing load when obtaining the impedance real part.

[0055] After the impedance real part of the battery 10 is obtained in step S104, the control unit 16 may obtain the deterioration degree of the battery 10 according to the impedance real part. The deterioration degree is a numerical representation of the degree of deterioration of the battery 10. In this case, the control unit 16 stores in advance deterioration degree information that associates the impedance real part of the battery 10 with the deterioration degree. The deterioration degree information may be generated by the control unit 16 by acquiring data that associates the impedance real part with the deterioration degree for a plurality of various batteries and performing machine learning using the acquired data as teacher data. The control unit 16 obtains the deterioration degree based on the impedance real part obtained in step S104 and the deterioration degree information.

[0056] When the battery internal impedance measuring device 100 is mounted on an electric vehicle such as an electric vehicle or a hybrid vehicle, CCA (Cold Cranking Ampere) may be used as the deterioration level of the battery 10. CCA is defined as the output current of a battery that can make the output voltage of the battery equal to or higher than a specified voltage when the battery is placed at a specified temperature for a specified time. The larger the CCA, the smaller the drop in output voltage during cranking and the better the battery performance. When the CCA as the deterioration level falls below a predetermined threshold, the control unit 16 may execute a deterioration display process, such as displaying in the vehicle cabin that the battery 10 has deteriorated.

[0057] The degree of deterioration of a battery may be expressed as the state of charge (SOH), which is defined as the percentage, ratio, or proportion of the current fully charged capacity (Ah) to the initial fully charged capacity (Ah).

[0058] 6A and 6B show the results of the experiment. The horizontal axis indicates the output voltage of the battery 10, and the vertical axis indicates the impedance real part. The impedance real part was repeatedly calculated using sample times t1 and t2 previously calculated by the operation in the calibration mode. FIG. 6A shows the results of an experiment in which the impedance real part was repeatedly calculated while discharging the charged battery 10. FIG. 6B shows the results of an experiment in which the impedance real part was repeatedly calculated while charging the battery 10. FIG. 6A and 6B show that the impedance real part of the battery 10 increases as the output voltage Vb of the battery 10 decreases. Compared to a certain number of experiments, N, the impedance real part is larger in the N+1th experiment, and compared to a certain number of experiments, N+1, the impedance real part is larger in the N+2th experiment, and the characteristics of the battery 10 are lost. That is, it is shown that the impedance real part increases as the frequency of the electrical load (charging and discharging) applied to the battery 10 increases.

[0059] 7 shows the configuration of a battery management system 102 according to a first application embodiment. The battery management system 102 includes a plurality of battery measuring devices 30, a telecommunication line 40, a storage computer 34, and a battery management device 32. Each battery measuring device 30 includes the above-described battery internal impedance measuring device 100. The telecommunication line 40 is a communication line available to the general public, such as the Internet. The storage computer 34 may be configured by one or more computers connected to the telecommunication line 40.

[0060] Each battery measuring device 30 measures the impedance real part of the battery 10 connected thereto, and transmits impedance measurement data in which a battery ID (IDentification) for identifying the battery 10 is associated with the impedance real part to a storage computer 34 via an electric communication line 40. The storage computer 34 stores the impedance measurement data transmitted from each battery measuring device 30. In the battery management device 32, an ID is designated by a user. That is, a battery ID is input to the battery management device 32. The battery management device 32 refers to the storage computer 34 via the electric communication line 40, and acquires the impedance measurement data associated with the ID.

[0061] The battery management system 102 reduces the user's workload in managing multiple batteries 10, even when multiple batteries 10 are distributed, such as when the batteries 10 are installed in multiple automobiles or in each home.

[0062] 8 shows the configuration of a battery internal impedance measuring system 104 according to a second application embodiment. The battery internal impedance measuring system 104 measures the impedance real part for each of n batteries B1 to Bn connected in series. The battery internal impedance measuring system 104 includes a measuring unit 36, a control unit 16, and a memory 18. The measuring unit 36 ​​includes a damped oscillation circuit 12 and a signal detector 14 corresponding to each of the batteries B1 to Bn.

[0063] A damped oscillation circuit 12 shown in Fig. 1 is connected to both ends of each of the batteries B1 to Bn. A signal detector 14 is individually connected to each of the damped oscillation circuits 12. The control unit 16 obtains the real part of the impedance of each of the batteries B1 to Bn by the same process as that executed by the control unit 16 according to the above embodiment. The batteries B1 to Bn may be in an unloaded state or may be supplying power to a load circuit.

[0064] According to the battery internal impedance measuring system 104, the impedance real part is obtained for each of the batteries B0 to Bn individually, regardless of whether the batteries B0 to Bn are unloaded or not. Furthermore, during measurement, each battery does not need to be removed from the damped oscillation circuit 12. This facilitates the operation of obtaining the impedance real part for each of the batteries B1 to Bn.

[0065] [Configuration of the present invention] Configuration 1: The device includes a damped oscillatory circuit connected to a battery to be measured, a drive circuit for electrically oscillating the damped oscillatory circuit, and a control unit, The control unit is Operates in measurement or calibration mode, The measurement mode is a mode in which the drive circuit is controlled to electrically oscillate the damped oscillation circuit, a damped oscillation signal relating to a time waveform of an electrical physical quantity in the damped oscillation circuit is obtained, and a real part of the impedance of the battery is calculated based on the damped oscillation signal; The calibration mode includes: A mode in which the drive circuit is controlled to electrically oscillate the damped oscillation circuit, a calibration damped oscillation signal related to a time waveform of an electrical physical quantity in the damped oscillation circuit is obtained, and a plurality of sample times on a time axis are obtained from the time waveform indicated by the calibration damped oscillation signal, The battery internal impedance measuring device is characterized in that, when operating in the measurement mode, the control unit acquires each sample value at a plurality of the sample times from the time waveform indicated by the damped oscillation signal, and calculates a real part of the impedance of the battery based on each sample value. Configuration 2: The battery internal impedance measuring device according to configuration 1, When operating in the calibration mode, the control unit: A battery internal impedance measuring device characterized in that a plurality of positions on a time axis at which the time waveform indicated by the calibration damped oscillation signal is at a maximum, or a plurality of positions on a time axis at which the time waveform indicated by the calibration damped oscillation signal is at a minimum, are obtained as the plurality of sample times. Configuration 3: The battery internal impedance measuring device according to configuration 1 or 2, The drive circuit includes: a switch connected to the damped oscillatory circuit; The device for measuring internal impedance of a battery, wherein the switch is turned on in a pulsating manner under the control of the control unit, thereby causing the damped oscillation circuit to oscillate electrically. Configuration 4: An internal impedance measuring device according to any one of configurations 1 to 3, The damped oscillatory circuit includes: A resonant inductor and a capacitive element are connected in series, The battery internal impedance measuring device is characterized in that the electrical physical quantity is a current flowing through the resonant inductor and the capacitive element. Configuration 5: The battery internal impedance measuring device according to configuration 4, The battery internal impedance measuring device is characterized in that the battery, the resonance inductor and the capacitive element are connected in series to form a resonance circuit. Configuration 6: The battery internal impedance measuring device according to configuration 4 or 5, a coupled inductor coupled to the resonant inductor; an electronic circuit connected to the coupled inductor; The electronic circuit includes: generating the damped oscillatory signal based on a voltage across the coupled inductor; The control unit is A battery internal impedance measuring device characterized by acquiring sample values ​​at three or more sample times from the damped oscillation signal, and compensating for a DC offset component contained in the damped oscillation signal based on the sample values. [Explanation of symbols]

[0066] 10, B1 to Bn batteries, 12 damped oscillation circuit, 14 signal detector, 16 control unit, 18 memory, 30 battery measurement device, 32 battery management device, 34 storage computer, 40 telecommunication line, 36 measurement unit, 100 battery internal impedance measurement device, 102 battery management system, 104 battery internal impedance measurement system, L1 resonance inductor, L2 coupling inductor, C0 capacitive element, R0 resistor, P resonance circuit, SW switch.

Claims

1. The device includes a damped oscillatory circuit connected to a battery to be measured, a drive circuit for electrically oscillating the damped oscillatory circuit, and a control unit, The control unit is Operates in measurement or calibration mode, The measurement mode is a mode in which the drive circuit is controlled to electrically oscillate the damped oscillation circuit, a damped oscillation signal relating to a time waveform of an electrical physical quantity in the damped oscillation circuit is obtained, and a real part of the impedance of the battery is calculated based on the damped oscillation signal; The calibration mode includes: A mode in which the drive circuit is controlled to electrically oscillate the damped oscillation circuit, a calibration damped oscillation signal related to a time waveform of an electrical physical quantity in the damped oscillation circuit is obtained, and a plurality of sample times on a time axis are obtained from the time waveform indicated by the calibration damped oscillation signal, The battery internal impedance measuring device is characterized in that, when operating in the measurement mode, the control unit acquires each sample value at a plurality of the sample times from the time waveform indicated by the damped oscillation signal, and calculates a real part of the impedance of the battery based on each sample value.

2. 2. The battery internal impedance measuring device according to claim 1, When operating in the calibration mode, the control unit: A battery internal impedance measuring device characterized in that a plurality of positions on a time axis at which the time waveform indicated by the calibration damped oscillation signal is at a maximum, or a plurality of positions on a time axis at which the time waveform indicated by the calibration damped oscillation signal is at a minimum, are obtained as the plurality of sample times.

3. 3. The battery internal impedance measuring device according to claim 1, The drive circuit includes: a switch connected to the damped oscillatory circuit; The device for measuring internal impedance of a battery, wherein the switch is turned on in a pulsating manner under the control of the control unit, thereby causing the damped oscillation circuit to oscillate electrically.

4. 3. The internal impedance measuring device according to claim 1, The damped oscillatory circuit includes: A resonant inductor and a capacitive element are connected in series, The battery internal impedance measuring device, wherein the electrical physical quantity is a current flowing through the resonant inductor and the capacitive element.

5. 5. The battery internal impedance measuring device according to claim 4, The battery internal impedance measuring device is characterized in that the battery, the resonance inductor and the capacitive element are connected in series to form a resonance circuit.

6. 5. The battery internal impedance measuring device according to claim 4, a coupled inductor coupled to the resonant inductor; an electronic circuit connected to the coupled inductor; The electronic circuit includes: generating the damped oscillatory signal based on a voltage across the coupled inductor; The control unit is A battery internal impedance measuring device characterized in that each sample value at three or more of the sample times is obtained from the damped oscillation signal, and a DC offset component contained in the damped oscillation signal is compensated for based on each sample value.

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