JP3379298B2 - Device for determining the life of sealed lead-acid batteries - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a life determining device for a sealed lead acid battery which is float-charged or trickle-charged.

[0002]

2. Description of the Related Art As a method for determining the life of a sealed lead-acid battery that has been conventionally flow-charged or trickle-charged,
The most common method has been to measure the specific gravity of the electrolyte. However, since the specific gravity of the electrolytic solution cannot be directly measured in the completely sealed sealed lead acid battery, a method of measuring the specific gravity of the electrolytic solution by installing a lead dioxide electrode for measuring the specific gravity of the electrolytic solution in a battery case (Japanese Patent Laid-Open No. 61- 294771), a method for detecting the elongation of the anode plate (JP-A-2-152170), and a method for measuring impedance (JP-A-4-198783).
Have been proposed.

However, among the above-mentioned methods of determining the life, the method of installing the electrode for measuring the specific gravity of the electrolytic solution in the battery case requires that the battery be processed, and the lead dioxide electrode is regularly charged. It is not practical because of the need. In addition, the method of detecting the elongation of the anode plate has the problems that it is necessary to process the battery in the same manner and that it is difficult to detect the elongation of all the anode plates, resulting in lack of reliability. It was

The most reliable method for determining the life is to measure the discharge capacity. However, in order to perform the discharge test, it is necessary to stop the operation of the equipment, and the discharge test requires a lot of labor and time. The point to do was not practical.

In order to solve this problem, it is possible to discharge the battery under an actual load. However, in the actual load discharge test, the time for backing up the equipment until the recovery charge is completed after discharging becomes longer than the rated value. There was a problem that the equipment could not be operated during that period.

Attempts have been made to estimate the discharge capacity from short-time discharge (Journal of the Institute of Electrical Engineers of Japan, 87, No. 5, V).
OL. 107-D, P606), it took a considerable discharge time of 1 hour or more at 0.1 C discharge to accurately estimate the discharge capacity.

Further, in the method of measuring impedance,
The correlation between discharge capacity and impedance is not always good,
When the discharge duration is estimated from the impedance, a considerably large error may occur, and the life judgment may be erroneous.

As a method of solving this point, there is a method of measuring impedance and performing a discharge test for a very short time.
This method uses the measured impedance value and very short time (5
The discharge capacity is estimated from the measured value of the discharge voltage (about a minute), and the result is more accurate than the estimation from either the impedance or the short-time discharge voltage (Journal of the Institute of Electrical Equipment, 1993, No). .12, VO
L. 13, P1247).

[0009]

However, in the above method of estimating the capacity from the impedance and the short-time discharge voltage, the impedance measurement accuracy becomes a problem. If the impedance measurement accuracy is poor, the discharge capacity estimation accuracy will naturally be poor, and there is a possibility of erroneous life determination.

Generally, the impedance of a sealed lead acid battery is obtained by measuring an AC voltage component contained in a terminal voltage when an alternating current of a constant amplitude is energized. It is difficult to measure accurately because it is easily affected by.

In the case of the stationary sealed battery of 2 V, 200 Ah, the impedance value is 1 mΩ or less at a frequency of about 10 Hz, and the AC voltage component appearing in the terminal voltage when an AC current of ± 2 A is applied is ± 2 mV or less. It has a very small value and is easily affected by noise. It is enough to increase the value of the energizing current, but the size of the element of the alternating current energizing part is increased,
It is difficult to increase the heat generation, power consumption, and cost.

In some cases, the ripple current may flow through the sealed lead-acid battery due to the float charge, and the ripple voltage may be included in the terminal voltage during measurement, resulting in an error. In an actual measurement of a system using an inverter as a load, there is an example in which a ripple voltage having a frequency of 50 Hz or 60 Hz is included in the terminal voltage of the sealed lead-acid battery as much as 10 mV during float charging. In this case, if the P-P value of the AC voltage component included in the terminal voltage of the sealed lead-acid battery is simply divided by the applied current to obtain the impedance value, a large error will occur.

Another problem is that the impedance and the short-time discharge voltage measurement value change depending on the temperature, which deteriorates the estimation accuracy of the discharge capacity.

An object of the present invention is to measure the impedance of a sealed lead acid battery accurately without being affected by ripple voltage and temperature, and to accurately estimate the discharge capacity together with the measured short-term discharge voltage. An object of the present invention is to provide a life determining device for a storage battery.

[0015]

A life determining device for a sealed lead-acid battery according to the present invention solves the above problems by the means described below.

Controlled by the current / discharge control unit, the AC current conducting unit transfers to the battery under test at a constant amplitude and a constant frequency, and
An alternating current whose cycle is an integral multiple of 100 ms is supplied for a predetermined period. Further, the battery under test is discharged to the discharging load for a predetermined time. The AC voltage component in the battery voltage is amplified by the AC voltage amplitude unit having a filter characteristic that allows only the same frequency component as the frequency of the AC current supplied to the battery to be measured. The impedance value calculation unit calculates the internal impedance value of the battery based on the output of the AC voltage amplification unit, and the calculation result is displayed on the display unit. The DC voltage component when the measured battery is discharged for a predetermined time is measured by the DC voltage measuring unit, and the battery ambient temperature is measured by the temperature detecting unit. The capacity estimation unit estimates and calculates the capacity of the measured battery from the impedance value of the measured battery obtained above, the DC voltage value at the time of discharging for a predetermined time, and the ambient temperature value, and displays the result on the display unit. .

The impedance value calculating section Fourier transforms the voltage response waveform of the output of the AC voltage amplifying section, obtains the amplitude of the AC voltage component having the same frequency component as the energizing current from the Fourier transformed value, and obtains the impedance value from this amplitude. calculate.

It is preferable that the alternating current conducting section has a period of the alternating current to be an integral multiple of 100 ms. In many cases, the ripple voltage is generated by a load such as an inverter. In that case, the ripple voltage is the commercial frequency, that is, 50
Or, it focuses on the fact that it becomes an integral multiple of 60 Hz. That is, when the Fourier transform is performed, a frequency component that is an integral multiple of the fundamental wave of the input waveform has a removing effect. Therefore, the greatest common divisor 10 Hz of the commercial frequency 50 or 60 Hz, that is, the period 1
10Hz if the input waveform cycle is set to an integral multiple of 00ms
The ripple voltage that is an integral multiple of can be removed. Therefore, if the cycle of the energizing current is an integral multiple of 100 ms, 50
Alternatively, a ripple voltage component that is an integral multiple of 60 Hz can be removed by Fourier transform.

Further, the impedance value calculating unit calculates the internal impedance value of the battery to be measured from the average voltage response waveform of the output of the AC voltage amplifying unit after a predetermined period after the start of the application of the alternating current to the battery to be measured. It should be set to. Specifically, an average voltage response waveform (for one cycle) is obtained from the voltage response waveforms when a plurality of cycles are energized, and the internal impedance value is calculated from this average voltage response waveform. This is to further reduce the effects of ripple voltage and noise, and by averaging the voltage response waveforms, frequency components other than integer multiples of the energization frequency are reduced, enabling more accurate measurement. Become.

In the life determining apparatus for a sealed lead-acid battery according to the present invention, the internal impedance of the battery and the short-time discharge voltage are measured together, and the battery discharge capacity is accurately estimated from these measured values. Then, by correcting the temperature based on the result of measuring the ambient temperature of the battery, the accuracy of estimating the discharge capacity can be improved. Further, in impedance measurement, the AC voltage amplification unit is provided with a filter characteristic that allows only a frequency component having the same frequency as that of the AC current to be passed, so that measurement error due to ripple voltage and noise is reduced. Further, the voltage response waveform of the output of the AC voltage amplification unit is Fourier-transformed, and the impedance value is calculated by obtaining the amplitude of the AC voltage component having the same frequency component as the energized current from the Fourier-transformed value. By reducing ripple voltage or noise that cannot be sufficiently removed by characteristics, impedance is measured with higher accuracy and battery capacity is estimated.

To summarize the above briefly, noise and ripple voltage components are present in an actual device, so that components other than the measurement frequency must be removed in order to accurately measure impedance. The AC voltage component may be measured through a filter that passes the measurement frequency component, but the accuracy is poor. Therefore, in the present invention, the voltage response waveform is Fourier-transformed to obtain the magnitude of only the measurement frequency component to improve the accuracy. Further, if the average value of the voltage response waveform is Fourier-transformed and the magnitude of only the measurement frequency component is obtained, it is possible to remove other than the measurement frequency, and the accuracy can be improved.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view showing an embodiment of the present invention, in which 1 is a sealed lead acid battery for determining the life, 2 is an alternating current energizing section that outputs an alternating current with a constant amplitude , a constant frequency and a cycle of an integral multiple of 100 ms. Is. The battery 1 to be measured is connected to the alternating current conducting part 2 through the contacts of the relay 3,
An alternating current when measuring the internal impedance of the battery 1 is supplied from the alternating current supply unit 2. The terminal voltage of the battery under test 1 becomes an input to the AC voltage amplifying section 4, and the AC voltage component generated in the terminal voltage of the battery under test 1 at the time of impedance measurement is an alternating current having a filter characteristic that passes only the same frequency component as the energized current. The voltage is amplified by the voltage amplifier 4.

Reference numeral 5 is a load resistance for a discharge test, and this load resistance is connected to the battery 1 to be measured through a contact of a relay 6. The terminal voltage of the battery 1 is also input to the DC voltage measuring unit 7, and the DC voltage of the battery during short-time discharge is measured by the DC voltage measuring unit 7. The DC voltage measuring unit 7 measures the DC voltage component of the output of the battery 1 and converts the measured value into a predetermined signal. Reference numeral 8 is a thermocouple for detecting a change in the ambient temperature of the battery 1, and the thermocouple 8 is connected to the temperature detection unit 9. The temperature detector 9 detects the ambient temperature of the battery 1 from the output of the thermocouple 8 and converts the detected temperature into a predetermined signal.

Reference numeral 10 is an alternating current conducting section 2 and relays 3 and 6.
The control unit has a microprocessor for controlling operations such as the above, and is a communication / discharge control unit for controlling energization of an alternating current to the battery 1 and discharging from the battery 1 to the load resistor 5.

The output of the AC voltage amplifying unit 4 is the impedance value calculating unit 1 realized by using a microprocessor.
1 is connected to the A / D conversion input. The impedance value calculation unit 11 performs a Fourier transform on the voltage response waveform of the output of the AC voltage amplification unit 4, and calculates the impedance value from the value obtained by the Fourier transform. Specifically, the impedance value is calculated from the average voltage response waveform of the output of the AC voltage amplification unit 4 after a predetermined period after the AC current starts to be supplied to the battery 1.

The outputs of the DC voltage measuring unit 7, the temperature detecting unit 9 and the impedance value calculating unit 11 are input to the capacity estimating unit 12 realized by using a microprocessor. The outputs of the DC voltage measuring unit 7 and the temperature detecting unit 9 are
It is used after being A / D converted by an A / D converter provided in the corresponding input section of the capacity estimation section 12. The respective outputs of the impedance value calculation unit 11 and the capacity estimation unit 12 are input to the display unit 13 having an LED segment as a display unit, and the calculated impedance value and the estimated capacity value of the battery 1 are displayed on the display unit 13. In the present embodiment, the impedance calculation display unit is composed of the impedance value calculation unit 11 and the display unit 13, and the capacity estimation display unit is the capacity estimation unit 12
And a display unit 13. In reality, the impedance value calculation unit 11 and the capacitance estimation unit 12 are realized by using a common microprocessor.

Next, the operation of this embodiment will be described. First,
When measuring the internal impedance of the battery 1 to be measured, after the contact of the relay 3 is turned ON by the communication / discharge control unit 10, an interrupt is applied at a constant cycle, and the AC current conducting unit 2
Is controlled to have a constant amplitude , a constant frequency, and a period of 10
An alternating current of an integral multiple of 0 ms is applied to the battery 1 for a predetermined period. The AC voltage amplifying unit 4 measures only the same frequency component as the frequency of the AC current conducted by the built-in filter, amplifies this frequency component, and outputs it. Then, the output voltage of the AC voltage amplification unit 4 is A / D converted by an A / D converter (not shown) built in the input unit of the impedance value calculation unit 11. A
The / D-converted AC voltage components are sequentially stored in a memory (not shown) built in the impedance value calculation unit 11. When the energization of the alternating current for a predetermined number of cycles or for a predetermined period is completed, the communication / discharge control unit 10 turns on the contact of the relay 3.
As the FF, the operation of the AC current supply unit 2 is terminated. The impedance value calculation unit 11 then calculates the internal impedance of the battery 1 and stores the calculation result in a built-in memory (not shown). Then, the impedance value calculation unit 11 sets the impedance value stored in the memory to L
The ED segment is displayed on the display unit 13 having display means. At the same time, the impedance value calculation unit 11
Outputs the impedance value stored in the memory to the capacitance estimating unit 12 as an impedance value signal.

When the impedance value calculation unit 11 calculates the impedance, the voltage response waveform output from the AC voltage amplification unit 4 is A / D-converted, then Fourier-transformed by the microprocessor, and the AC-transformed AC voltage is obtained. The amplitude of the AC voltage component having the same frequency component as the energizing AC current is obtained from the component, and the impedance value is calculated from this amplitude. As a result, the ripple voltage or noise that is not sufficiently removed by the filter characteristics of the AC voltage amplifier 4 can be reduced, and the impedance value can be calculated with higher accuracy. The specific impedance value is
It is obtained by dividing the amplitude value of the AC voltage component of the measurement frequency obtained by Fourier transform by the value of the energizing current.

Further, in the apparatus of the present invention, a short-time discharge test of the battery 1 to be measured is performed. When performing a short-time discharge test, the conduction / discharge control unit 10 turns on the contact of the relay 6 for a predetermined time (for example, 30 seconds), and causes a short-time discharge current to flow from the battery 1 to the load resistor 5. This discharge time may be the time until the discharge voltage is determined, and may be set according to the magnitude of the load resistance. Then, the battery voltage at the time of discharging is measured by the DC voltage measuring unit 7, and the battery voltage signal output from the DC voltage measuring unit 7 is input to the A / D conversion input unit of the capacity estimating unit 12. The capacity estimation unit 12 stores the battery voltage measured by the DC voltage measurement unit 7 as a discharge voltage in a memory (not shown). Further, an ambient temperature signal indicating the ambient temperature value of the battery 1 detected by the thermocouple 8 and the temperature detecting unit 9 is input to the A / D conversion input unit of the capacity estimating unit 12, and the ambient temperature value of the battery 1 is the capacity. It is stored in a memory (not shown) of the estimation unit 12.

The capacity estimating unit 12 A / D-converts the impedance value of the battery 1 to be measured, the battery voltage signal at the time of short-term discharge, and the ambient temperature signal, which are stored in the memory. Is used to estimate the discharge capacity by the microprocessor. Specifically, the impedance value and the short-time discharge voltage value are temperature-corrected with the ambient temperature of the battery 1, and the discharge capacity is estimated and calculated using the LE value.
The calculation result is displayed on the display unit 13 having the D segment as the display means. This estimation calculation of the discharge capacity is performed by the journal of the Institute of Electrical Equipment, "1993, N
o. 12, VOL. 13, P1247 ”may be used.

In the present embodiment, the cycle of the AC current supplied to the battery 1 by the AC current supply unit 2 is set to an integral multiple of 100 ms. The reason is as described in the section of means for solving the problem.
Will be explained. That is, the reason why the cycle of the alternating current is an integral multiple of 100 ms is that the ripple voltage is often generated in a load such as an inverter. In that case, the ripple voltage is an integral multiple of the commercial frequency, that is, 50 or 60 Hz. It focuses on that. FIG. 2 shows an error when the amplitude of the fundamental wave component is calculated by Fourier transforming a waveform in which a high frequency component having a frequency of 10 Hz to 60 Hz is superimposed when the amplitude is 100 as the waveform to be Fourier transformed. Is a plot of. As shown,
The error is 0% for frequencies that are integer multiples of the fundamental wave component, and there is no influence of the fundamental wave component.
The 0 Hz component can also be removed. That is, when the Fourier transform is performed, since the frequency component that is an integral multiple of the fundamental wave of the input waveform has a removing effect, the maximum common divisor 10 Hz of the commercial frequency 50 or 60 Hz, that is, the input waveform cycle is set to an integral multiple of the cycle 100 ms. For example, the ripple voltage that is an integral multiple of 10 Hz can be removed. Therefore, the cycle of the energizing AC current is 1
If it is an integral multiple of 00 ms, the ripple voltage component of an integral multiple of 50 or 60 Hz can be removed by Fourier transform.

Further, in the present embodiment, the impedance calculation section 11 starts the energization of the alternating current to the battery 1 to be measured, and then, after the alternating current of a predetermined period (specifically, 8 cycles) is energized. The voltage response waveform data output from the AC voltage amplifying unit 4 is read from the above-mentioned memory (not shown), an average voltage response waveform is obtained based on the read data, and an impedance value is calculated from this average voltage response waveform. ing. After the start of energization, not using the data for a predetermined period takes time until the voltage response waveform of the battery stabilizes, and it takes time until the voltage response waveform of the AC voltage amplifying unit having the filter characteristic stabilizes. This is because it costs. This predetermined period may be the shortest time until the voltage response waveform stabilizes. By using the average voltage response waveform in this way, the influence of ripple voltage and noise can be further suppressed. This will be described with reference to FIG. In this example, a case is assumed in which a ripple voltage having the same amplitude as the fundamental frequency is superimposed at a frequency 4.2 times the frequency of the energizing alternating current, and an average of 16 cycles is taken. As shown in the figure, the ripple voltage component is superimposed on the input waveform a, but the ripple voltage component is reduced in the waveform b which is integrated and averaged 16 times.

Further, as in the case of FIG. 2, the fundamental frequency of the alternating current is 10 Hz, and the waveform obtained by superimposing the harmonics of the frequency of 10 Hz to 60 Ha is used as the input waveform. The error characteristic when the amplitude of the basic component is obtained is shown in FIG. As shown in FIG. 4, the error is small even at frequencies other than integral multiples of the fundamental frequency, and the influence of ripple voltage and noise can be reduced.

Next, the actual operating conditions in this embodiment will be shown. The sealed lead-acid battery whose life is to be judged is rated at 2V, 2
It is a stationary sealed lead acid battery of 00Ah. The AC current applied when measuring the impedance of this battery had a frequency of 10 Hz,
It is ± 2 A, and this AC current is supplied for 25 cycles, and the voltage response waveform data of 9 cycles to 25 cycles are integrated and averaged to perform Fourier transform to calculate the impedance value. The upper limit of impedance measurement is 2.5 mΩ, and the number of sampling points of the voltage response waveform data is 128 points per cycle. The short-time discharge is performed at a discharge current of about 46 A for 30 seconds.

Next, the results of actual measurement of the ripple voltage characteristic, which is one of the features of the present invention, will be shown. The objects to be measured were two shunt resistors having resistance values of 1 mΩ and 0.333 mΩ, respectively. 10nV, 50Hz as ripple voltage
Fig. 5 shows the results of 100 measurements with the ripple voltage of Fig.
Shown in. As shown in the figure, the maximum error and the standard deviation of the error were almost the same regardless of the presence or absence of the ripple voltage, and the influence of the presence of the ripple voltage did not appear in the measured value. Therefore, it can be determined that the ripple voltage does not affect the measured impedance value.

[0036]

As described above, according to the life determining apparatus for a sealed lead-acid battery according to the present invention, calculation of the internal impedance of the target battery and measurement of the short-time discharge battery are performed together, and the impedance value and Since the discharge capacity of the battery is estimated based on the value obtained by correcting the discharge voltage value with the measured ambient temperature of the battery, the discharge capacity can be accurately estimated and the life of the battery can be satisfactorily determined.

Further, according to the present invention, the amplified output of the alternating voltage between the battery terminals when the alternating current is applied to the battery is Fourier transformed, and the amplitude of the alternating voltage having the same frequency component as the applied current is obtained from the converted value. Since the impedance value is calculated, the influence of the ripple voltage and noise can be reduced, the impedance value can be calculated with high accuracy, and the battery capacity can be estimated. As a result, the reliability of battery life determination can be improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

FIG. 2 is a characteristic curve diagram showing an error between a harmonic frequency of a fundamental wave and an amplitude of a fundamental wave component after Fourier transform.

FIG. 3 is a characteristic curve diagram showing a change in waveform when a voltage response waveform with respect to an AC input of a battery is integrated and averaged.

FIG. 4 is a characteristic curve diagram showing an error in the amplitude of the fundamental wave component after Fourier transform when the harmonic frequency of the AC input and the voltage response waveform are integrated and averaged.

FIG. 5 is a characteristic explanatory diagram showing an error when a ripple voltage exists.

[Explanation of symbols]

1 Sealed lead acid battery to be measured 2 AC current energizer 3,6 relay contact 4 AC voltage amplifier 5 Discharge load resistance (discharge load section) 7 DC voltage measurement section 8 thermocouple 9 Temperature detector 10 communication / discharge control unit 11 Impedance value calculator 12 Capacity estimation section 13 Display

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-155778 (JP, A) JP-A-4-244981 (JP, A) JP-A-3-180770 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G01R 31/36 H01M 10/42-10/48 H01J ^7/ 00-7/12

Claims (3)

(57) [Claims] 1. A constant amplitude , a constant frequency, and a period of 1
An alternating current conducting part (2) for supplying an alternating current of an integral multiple of 00 ms to the battery under test, and a filter characteristic for passing only a frequency component having the same frequency as the frequency of the alternating current. AC voltage amplification unit (4) that detects a voltage component and amplifies it
An impedance value calculating unit (11) for calculating an impedance value from the output of the AC voltage amplifying unit; a discharging load unit (5) for discharging the battery under test; and the AC current conducting unit to the battery under test. And a discharge / discharge control unit (1) for causing the discharge load unit to discharge the battery under test for a predetermined time.
0), a DC voltage measuring unit (7) for measuring a DC voltage component of the measured battery, and a temperature detection unit (8, 8) for measuring the ambient temperature of the measured battery.
9) and a capacity estimation unit (12) for estimating and calculating the capacity of the measured battery from the impedance value of the measured battery, the DC voltage value when discharging for a certain period of time, and the ambient temperature value, The calculation unit (11) Fourier transforms the voltage response waveform of the output of the AC voltage amplification unit (4),
A life determining device for a sealed lead storage battery, characterized in that an amplitude of an AC voltage component having the same frequency component as that of an energized current is obtained from a Fourier-transformed value, and an impedance value is calculated from the amplitude. 2. A constant amplitude , a constant frequency, and a period of 1
An alternating current conducting part (2) for supplying an alternating current of an integral multiple of 00 ms to the battery under test, and a filter characteristic for passing only a frequency component having the same frequency as the frequency of the alternating current. AC voltage amplification unit (4) that detects a voltage component and amplifies it
And an impedance value calculation display unit (11, 1) for calculating and displaying an impedance value from the output of the AC voltage amplification unit.
3), a discharging load part (5) for discharging the battery to be measured, and energization of the alternating current conducting part to the battery to be measured for a predetermined period, and the discharging load part to the battery to be measured. The discharge / discharge control unit (1
0), a DC voltage measuring unit (7) for measuring a DC voltage component of the measured battery, and a temperature detection unit (8, 8) for measuring the ambient temperature of the measured battery.
9), and a capacity estimation display section (12, 13) for estimating and displaying the capacity of the measured battery from the impedance value of the measured battery, the DC voltage value at the time of discharging for a fixed time, and the ambient temperature value. The impedance value calculating and displaying unit (11, 13) Fourier transforms the voltage response waveform of the output of the AC voltage amplifying unit, and calculates the amplitude of the AC voltage component of the same frequency component as the energized current from the Fourier transformed value. A life determining device for a sealed lead-acid battery, which is characterized by calculating and displaying an impedance value from the amplitude. 3. The impedance value calculation unit (11)
Is a predetermined period after the AC current starts to flow to the battery to be measured.
Subsequent average voltage response waveform of the output of the AC voltage amplifier
It is characterized by calculating and displaying the impedance value from
The life determining device for a sealed lead-acid battery according to claim 1 .