JP2020169887A - Deterioration diagnosis device and deterioration diagnosis method for storage battery - Google Patents

Abstract

To provide a deterioration diagnosis method for storage batteries that estimates internal states of the storage batteries even in specific use environments and enables deterioration diagnosis.SOLUTION: A deterioration diagnosis method for a storage battery includes: a recording step of recording battery voltage and battery current at a predetermined time after starting a device; a capacity calculation step of calculating a DC error and a differential capacity from waveforms of the battery voltage and the battery current before and after when the storage battery switches from discharging to charging; a correction step of subtracting the DC error from the battery current to find a correction value of the battery current; and an internal resistance calculation step of calculating DC internal resistance from the waveforms of the battery voltage before and after when the storage battery switches from discharging to charging and the correction value. The deterioration diagnosis method further includes a diagnosis step of performing deterioration diagnosis using the differential capacity and the DC internal resistance.SELECTED DRAWING: Figure 2

Description

The present invention relates to, for example, a deterioration diagnosis device and a deterioration diagnosis method for a storage battery mounted on a railway vehicle, an uninterruptible power supply, or the like.

In recent years, storage batteries such as lithium-ion batteries have begun to be adopted in automobiles and railway vehicles instead of conventional lead batteries. This storage battery is expected to have a much longer life than a lead battery, but the life when actually used in a railway vehicle, for example, has not been known so far.

It is known that such a storage battery shortens the usage time and the output due to a decrease in capacity and an increase in internal resistance by repeating charging and discharging, and the storage battery deteriorated by long-term use is replaced. There is a need to. Therefore, it was necessary to carry out regular deterioration diagnosis after mounting on the vehicle and plan battery replacement at an appropriate timing.

Conventional methods for diagnosing deterioration of a storage battery include, as described in Patent Document 1, for example, a measurement step for measuring a battery temperature, current, and voltage during charging or discharging of a secondary battery, and the measured battery. An estimation step of estimating the internal resistance value of the battery using the temperature, current, and voltage data and the data showing the relationship between the open circuit voltage of the positive and negative active materials held in advance and the charge amount. The calculation step of calculating the reaction resistance component, the ohmic resistance component, and the diffusion resistance component from the estimated internal resistance, the internal resistance value, and the temperature of the reaction resistance component, the ohmic resistance component, and the diffusion resistance component, respectively. A battery performance estimation method having a correction step of correcting and correcting to a total value is known.

Japanese Unexamined Patent Publication No. 2014-149280

The conventional evaluation method for storage batteries described above is intended for use in electric vehicles, hybrid vehicles, hybrid motorcycles, etc., and enables accurate deterioration diagnosis in consideration of the influence of battery temperature during use. there were. However, in recent years, vehicles equipped with storage batteries in railway vehicles have been put into practical use, and the deterioration diagnosis method for storage batteries used in conventional electric vehicles is not suitable as a deterioration diagnosis method for storage batteries installed in railway vehicles. was there.

This is due to the usage environment of the storage battery in the control circuit of the railway vehicle. Specifically, the usage environment of the storage battery in the control circuit of the railway vehicle is as follows. (1) Since the battery starts discharging before the vehicle data recording system starts, the data before the start of discharging is not recorded. (2) After the vehicle starts, power is supplied from the overhead wire and the battery is constantly charged and discharged. It does not include the energized state, (3) Normally, only a shallow discharge of about 10% is performed, and a deep discharge of several tens of percent order is not performed except in an abnormal situation such as an overhead wire power failure. (4) Control circuit load The discharge waveform to and the charge waveform from the vehicle rectifier are monotonous and have little fluctuation. (5) The DC error of the battery current sensor cannot be ignored. Here, the conventional storage battery deterioration diagnosis method has a problem that the charge / discharge cycle is complicated depending on the usage situation, including the non-energized state, and the conventional diagnosis method cannot be simply adopted for the railway vehicle. It was. Further, in the conventional method for diagnosing deterioration of a storage battery, it is necessary to deeply discharge the storage battery in order to obtain a charge / discharge curve, and as shown in (3), usually only a shallow discharge is performed and the deep discharge is performed. In the case of a control circuit of a railroad vehicle, which rarely becomes a discharge, there is a problem that the diagnosis cannot be made by the conventional deterioration diagnosis method.

Therefore, an object of the present invention has been made to solve the above-mentioned problems, and a storage battery deterioration diagnosis device capable of estimating the internal state of the storage battery and diagnosing deterioration even in the above-mentioned usage environment. The purpose is to provide a deterioration diagnosis method.

The method for diagnosing deterioration of a storage battery according to the present invention includes a recording step of recording the battery voltage and the battery current for a predetermined time after the device is started, and DC from the waveforms of the battery voltage and the battery current before and after the storage battery is switched from discharging to charging. A capacity calculation step for calculating the error and the differential capacity, a correction step for obtaining a correction value for the battery current by subtracting the DC error from the battery current, and the battery voltage and the correction before and after the storage battery switches from discharging to charging. It is characterized by including an internal resistance calculation step of calculating a DC internal resistance from a value waveform, and a diagnostic step of performing deterioration diagnosis using the differential capacitance and the DC internal resistance.

Further, in the storage battery deterioration diagnosis method according to the present invention, in the capacity calculation step, the charging side interval of a predetermined time interval in the charging period and the switching time of switching from discharging to charging are calculated from the switching time of switching from discharging to charging. It is preferable to calculate the DC error and the differential capacitance using the discharge side interval of a predetermined time interval in the discharge time calculated from.

Further, in the method for diagnosing deterioration of a storage battery according to the present invention, in the internal resistance calculation step, the charging side time and the discharging side time are determined so that the amount of charge obtained by integrating the correction values becomes substantially equal before and after switching from discharging to charging. It is preferable to calculate the DC internal resistance using the corrected values of the respective voltage values and currents in the charging side time and the discharging side time.

Further, in the storage battery deterioration diagnosis method according to the present invention, it is preferable that the capacity calculation step and the internal resistance calculation step use only the data at the time when the transient response of the data recorded in the recording step has converged. is there.

Further, the storage battery deterioration diagnosis device according to the present invention includes a control circuit in which the storage battery is connected without a power conversion device, a charging device unit of the control circuit and a main circuit for supplying power to the storage battery, and the charging. In a deterioration diagnosis device for a storage battery of a railway vehicle provided with a main power supply unit of a main circuit that supplies power to the device unit, a battery state acquisition unit that acquires the voltage and current of the storage battery and an activated state of the charging device unit or the above Of the vehicle state acquisition unit that acquires the activation state of the main power supply unit, the waveform recording unit that records the waveforms obtained by the battery state acquisition unit and the vehicle state acquisition unit, and the waveform recorded by the waveform recording unit. Before and after the storage battery switches from discharging to charging, the DC error and the differential capacity are calculated from the waveform extraction unit that extracts the period during which the transient response of the voltage of the storage battery is converging and the waveform extracted by the waveform extraction unit. The differential capacity calculation unit, the correction unit that subtracts the DC error from the current of the storage battery to obtain the correction value of the current of the storage battery, and the correction waveform obtained by converting the current of the storage battery into the correction value among the extracted waveforms. It is characterized by including an internal resistance calculation unit that calculates the DC internal resistance from the above, and a diagnostic unit that performs deterioration diagnosis using the differential capacitance and the DC internal resistance.

According to the features of the present invention, deterioration diagnosis of a storage battery used in a device such as a control circuit of a railroad vehicle or an uninterruptible power supply can be performed by a data recording system or an arithmetic system, and thus a special test for deterioration diagnosis can be performed. And equipment is not required, and the cost can be suppressed without installing an expensive current sensor with a small DC error for deterioration diagnosis.

FIG. 6 is a schematic diagram of a circuit configuration of a railway vehicle equipped with a storage battery according to an embodiment of the present invention. The flowchart which shows the deterioration diagnosis method of the storage battery which concerns on embodiment of this invention. Graph of current voltage waveform used in capacity calculation process. The figure which shows the equivalent circuit of the storage battery which concerns on embodiment of this invention. The figure which shows an example of the battery equivalent circuit for transient response convergence judgment. Graph of current voltage waveform used in internal resistance calculation process. The figure which shows the structural example of the deterioration diagnosis apparatus which concerns on this embodiment.

Hereinafter, preferred embodiments for carrying out the present invention will be described with reference to the drawings. It should be noted that the following embodiments do not limit the invention according to each claim, and not all combinations of features described in the embodiments are essential for the means for solving the invention. ..

FIG. 1 is a schematic diagram of a circuit configuration of a railroad vehicle equipped with a storage battery according to an embodiment of the present invention, and FIG. 2 is a flowchart showing a deterioration diagnosis method for the storage battery according to the embodiment of the present invention. Is a graph of a current-voltage waveform used in the capacitance calculation process, FIG. 4 is a diagram showing an equivalent circuit of a storage battery according to an embodiment of the present invention, and FIG. 5 is a diagram of a battery equivalent circuit for determining transient response convergence. FIG. 6 is a diagram showing an example, FIG. 6 is a graph of a current-voltage waveform used in the internal resistance calculation step, and FIG. 7 is a diagram showing a configuration example of a deterioration diagnosis device according to the present embodiment.

As shown in FIG. 1, the simulated circuit configuration of the railway vehicle equipped with the storage battery according to the present embodiment includes a main circuit including an overhead wire or a generator, and a control circuit and a service device branched from the charging device portion of the auxiliary power supply device. It consists of an auxiliary circuit. The storage battery is connected to the control circuit for backup, and is usually composed of DC100V or DC24V.

Next, a method of diagnosing deterioration of the storage battery of the railway vehicle equipped with the storage battery according to the present embodiment will be described. As shown in FIG. 2, the deterioration diagnosis method of the storage battery of the railway vehicle equipped with the storage battery according to the present embodiment measures the waveforms of the battery current and the battery voltage for a predetermined time (for example, about 30 minutes) after the start of the railway vehicle. Recording step (S101), capacity calculation step (S102) for calculating DC error and differential capacity from waveforms of battery voltage and battery current before and after the storage battery switches from discharging to charging, and capacity calculation step for battery current (S102). The correction step (S103) for obtaining the correction value of the battery current by subtracting the DC current error calculated in step 2, and the DC voltage from the waveform of the correction value obtained in the correction step (S103) and the battery voltage before and after the storage battery is switched from discharging to charging. A diagnostic step of diagnosing deterioration of the storage battery using the internal resistance calculation step (S104) for calculating the internal resistance, the differential capacitance obtained in the capacitance calculation step (S102), and the DC internal resistance obtained in the internal resistance calculation step (S104). (S105) and.

In the recording step (S101), the waveforms of the current and voltage for a predetermined time (for example, about 30 minutes) after the start of the railway vehicle are recorded. In the recording step (S101), various conventionally known recording means can be adopted, and for example, a hard disk of a computer, an SSD, or the like is preferably used. Further, the current value and the voltage value of the storage battery are measured over time using various ammeters and voltmeters. Further, the recording time in the recording step (S101) is not limited to about 30 minutes, and a period other than the period without data recording immediately after the orbit can be sufficiently recorded, and the transient response described later can be appropriately excluded. If so, the setting can be changed as appropriate.

In the capacity calculation step (S102), as shown in FIG. 3, the switching time ct for switching from discharging to charging is specified from the battery current value. Next, the charging side intervals tb1 and tb2 at predetermined time intervals in the charging period calculated from the switching time ct, and the discharging side intervals ta1 and ta2 at predetermined time intervals in the discharging period calculated from the switching time ct. Determine. Here, the charging side intervals tb1 and tb2 and the discharging side intervals ta1 and ta2 use the data at the time when the transient response has converged, and the other intervals are rejected. Thereafter, the charging-side spacing tb1, tb2 and discharge side interval ta1, the charging-side voltage difference corresponding to ta2 [Delta] V _b, the charging-side time difference Delta] t _b, the discharge-side voltage difference [Delta] V _a and current voltage waveforms in FIG. 3 the discharge side time difference Delta] t _a Read from the graph of. Further, the charges at the charging side intervals tb1 and tb2 and the discharging side intervals ta1 and ta2 are integrated to obtain the charging side charge difference Δq _b and the discharging side charge difference Δq _a .

In the capacity calculation step (S102), it is preferable to calculate the DC error and the differential capacity using the battery equivalent circuit as shown in FIG. Specifically, the DC error I _ofs is calculated using the following mathematical formula 1, and the differential capacitance C is calculated using the following mathematical formula 2.

Here, various determination methods can be applied as a determination method for determining that the transient response has converged, but it is preferable to use, for example, the battery equivalent circuit shown in FIG. Specifically, in FIG. 5, although a two-stage series (i = 2) for the purpose of explanation, _{C i} and _{R i (i = 1,2,3, ···} ) series number of stages of the battery type It may be changed to suit. Opening the C _i in this circuit (capacitance zero) Tosureba match the configuration of FIG. That is, R = R ₀ + R ₁ + R ₂ . Incidentally, R _i and C _i is not a parameter identification of interest may in numerical value in advance calculated (fixed value during operation). This allows more simplified approach to identify all R _i and C _i.

Next, since the steady-state value of the transient response estimated voltage when the current value I continues for a sufficiently long time is (R ₀ + R ₁ + R ₂ ) × I, the ratio γ of this to the current value is used to determine the transient response. Make a convergence test. The relational expression of the voltage _Vri of each parallel circuit is expressed by the following equation 3.

This formula 3 is discretized at the sample time T (s), and then formula 4 is obtained. Although this formula 4 was obtained by applying a simple Euler method, various conventionally known methods may be applied.

Here, in Equation 4, n represents a value at time t = nT, and the calculation is started with the initial value of _{Vri at} t = 0 being 0, and the value _{Vri (n)} at the current time t = nT is obtained. .. From here, the ratio γ is given by the following mathematical formula 5.

When this ratio γ satisfies the condition of the following equation 6, it can be determined that the transient response has converged.

Here, the smaller Δγ is, the more precise the convergence test can be performed. However, since it takes time to converge, it is preferable to adjust Δγ when first calculating the new storage battery. Is.

In the correction step (S103), the observed value I of the battery current is the sum of the correction value I'and the DC error I _ofs , so the DC error I _ofs is subtracted from the observed value I to obtain the current correction value I'. ..

In the internal resistance calculation step (S104), as shown in FIG. 6, when the DC internal resistance is calculated from the waveforms of the battery voltage and the correction value before and after the storage battery switches from discharging to charging using the correction value I'and the battery voltage. Suitable.

Specifically, the period in which the transient response is converged is obtained by the same method as in the capacitance calculation step (S102) described above, and the charge amount obtained by integrating the current correction value is switched from the period in which the transient response is converged. The charge side time tb and the discharge side time ta that are substantially equal before and after the time tc are obtained. After that, the charging side voltage value V _b , the charging side current value I ′ _b , the discharging side voltage value V _a, and the discharging side current value I ′ _a corresponding to the charging side time tb and the discharging side time ta are set as the current voltage waveform in FIG. Read from the graph of.

Next, the DC internal resistance R is calculated by the mathematical formula 7 using these values.

After that, if the open circuit voltage at time tb is obtained from Equation 8, the open circuit voltage can be continuously estimated based on the integration of the current I', and the battery capacity can also be estimated from this.

Next, in the diagnostic step (S105), it is determined whether or not the obtained differential capacitance C and the DC internal resistance R do not exceed a predetermined threshold value. This threshold value can be appropriately determined according to the situation of the storage battery used. For example, since the differential capacitance C and the DC internal resistance R are affected by the charge rate and temperature of the storage battery, a judgment threshold value different for each charge rate and temperature is determined and held in advance in the deterioration diagnosis, and this is used. This makes it possible to make a practical deterioration judgment.

By performing the deterioration diagnosis of the storage battery in this way, the usage environment of the storage battery is (1) the battery starts discharging before the data recording system of the vehicle starts, so that the data before the start of discharging is not recorded. 2) After the vehicle is started, power is supplied from the overhead wire and it is constantly charged and discharged, so it does not include a non-energized state. (3) Normally, only a shallow discharge of about 10% is performed, except when there is an abnormality such as an overhead wire power failure. Deep discharge on the order of several tens of percent is not performed, (4) the discharge waveform to the control circuit load and the charge waveform from the vehicle rectifier are monotonous and have little fluctuation, (5) DC error of the battery current sensor. Even if it cannot be ignored, it is possible to appropriately diagnose the deterioration of the storage battery. In addition, if these deterioration diagnoses can be performed by the data recording system or arithmetic system provided in the railway vehicle, no special test or device for deterioration diagnosis is required, and DC error is required for deterioration diagnosis. The cost can be suppressed without installing an expensive current sensor with a small amount of data.

Further, the storage battery deterioration diagnosis method according to the present embodiment can be realized by using the storage battery deterioration diagnosis device as shown in FIG. 7. Specifically, a control circuit in which the storage battery is connected without a power conversion device, a charging device unit of the control circuit and a main circuit that supplies power to the storage battery, and a main unit that supplies power to the charging device unit. It is preferable to use a deterioration diagnosis device for a storage battery of a railway vehicle provided with a main power supply unit of the circuit.

Here, the battery state acquisition unit acquires the voltage and current of the storage battery, the vehicle state acquisition unit acquires the activation state of the charging device unit or the activation state of the main power supply unit, and the waveform recording unit acquires the battery state acquisition unit. The waveform obtained by the vehicle state acquisition unit is recorded, and the waveform extraction unit collects the transient response of the voltage of the storage battery before and after the storage battery switches from discharging to charging among the waveforms recorded by the waveform recording unit. The differential capacity calculation unit calculates the DC error and differential capacity from the waveform extracted by the waveform extraction unit, and the correction unit subtracts the DC error from the current of the storage battery to obtain the correction value of the current of the storage battery. The internal resistance calculation unit calculates the DC internal resistance from the corrected waveform obtained by converting the current of the storage battery into the correction value from the extracted waveform, and the diagnostic unit uses the calculated differential capacitance and DC internal resistance to deteriorate. Make a diagnosis.

As described above, since the storage battery deterioration diagnosis device according to the present embodiment particularly has a railway state acquisition unit, it is possible to more accurately determine the timing at which the storage battery switches from discharging to charging. That is, it can be determined that the storage battery switches from discharging to charging at the timing when the main power supply unit and / or the charging device unit starts operating. This makes it possible to reduce the possibility of erroneously estimating the differential capacitance C and the DC internal resistance R using the data at the wrong timing.

In the above-described embodiment, the case where the storage battery is used in a railway vehicle has been described, but the present invention is not limited to the case where it is used in a railway vehicle, and is also applied to applications such as an uninterruptible power supply. It is possible. Further, the storage battery is preferably a lithium ion battery because it has a high coulombic efficiency when the battery is charged and discharged, and the hysteresis property that the open circuit voltage curve differs between the discharge and the charge can be ignored in the charge and discharge. is there. However, any battery that satisfies this premise can be applied not only to a lithium ion battery but also to various batteries.

tk switching time tb1, tb2 Charging side interval ta1, ta2 Discharging side interval ΔV _b Charging side voltage difference Δt _b Charging side time difference ΔV _a Discharging side voltage difference Δt _a Discharging side time difference Δq _b Charging side charge difference Δq _a Discharging side charge difference I _ofs DC error C differential capacity I observed value I'correction value tb charge side time ta discharge side time V _b charge side voltage value _I'b charge side current value V _a discharge-side voltage value _I'a discharge-side current value S101 recording step S102 Capacity calculation process S103 Correction process S104 Internal resistance calculation process S105 Diagnosis process

Claims (5)

A recording process that records the battery voltage and battery current for a predetermined time after the device is started,
A capacity calculation process for calculating the DC error and the differential capacity from the waveforms of the battery voltage and the battery current before and after the storage battery switches from discharging to charging,
A correction step of subtracting the DC error from the battery current to obtain a correction value for the battery current,
It includes an internal resistance calculation step of calculating the DC internal resistance from the waveforms of the battery voltage and the correction value before and after the storage battery switches from discharging to charging.
A method for diagnosing deterioration of a storage battery, which comprises a diagnostic step of performing deterioration diagnosis using the differential capacity and the DC internal resistance. In the method for diagnosing deterioration of a storage battery according to claim 1,
In the capacity calculation step, discharging is performed at a predetermined time interval in the discharging time, counting from the charging side interval of a predetermined time interval in the charging period and the switching time of switching from discharging to charging, counting from the switching time of switching from discharging to charging. A method for diagnosing deterioration of a storage battery, which comprises calculating the DC error and the differential capacity using a side spacing. In the method for diagnosing deterioration of a storage battery according to claim 1 or 2.
In the internal resistance calculation step, the charging side time and the discharging side time are determined so that the amount of charge obtained by integrating the correction values becomes substantially equal before and after switching from discharging to charging, and the charging side time and the discharging side time are set respectively. A method for diagnosing deterioration of a storage battery, which comprises calculating the DC internal resistance using a voltage value and a current correction value. In the method for diagnosing deterioration of a storage battery according to any one of claims 1 to 3.
A method for diagnosing deterioration of a storage battery, wherein the capacity calculation step and the internal resistance calculation step use only data at a time when the transient response of the data recorded in the recording step has converged. A control circuit in which the storage battery is connected without going through a power converter,
A charging device unit of a main circuit that supplies electric power to the control circuit and the storage battery,
In a deterioration diagnosis device for a storage battery of a railway vehicle provided with a main power supply section of a main circuit that supplies electric power to the charging device section.
A battery state acquisition unit that acquires the voltage and current of the storage battery, and
A vehicle state acquisition unit that acquires the activation state of the charging device unit or the activation state of the main power supply unit, and
A waveform recording unit that records the waveforms obtained by the battery state acquisition unit and the vehicle state acquisition unit, and
Of the waveforms recorded by the waveform recording unit, a waveform extraction unit that extracts a period before and after the storage battery switches from discharging to charging and during which the transient response of the voltage of the storage battery converges,
A differential capacity calculation unit that calculates DC error and differential capacity from the waveform extracted by the waveform extraction unit,
A correction unit that subtracts the DC error from the current of the storage battery to obtain a correction value of the current of the storage battery.
Among the extracted waveforms, an internal resistance calculation unit that calculates the DC internal resistance from the correction waveform obtained by converting the current of the storage battery into the correction value is provided.
A deterioration diagnosis device for a storage battery, comprising a diagnostic unit that performs deterioration diagnosis using the differential capacity and the DC internal resistance.

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