JP2003132960A - Method for detecting charged state of storage battery used for power supply system, and method for deciding degradation of storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply system comprising an independent power source such as a fuel cell and a storage battery, in which the charged state of the storage battery is accurately detected, and the degradation of the storage battery is accurately decided, based on the acquired charged state value. SOLUTION: A method for detecting the charged state of a storage battery is provided which uses a power supply system that supplies power to a load 3 by implementing a fuel cell 1 of an independent power source and a storage battery 7, and supplies an output to the load 3 while charging the storage battery 7 if the power consumption of the load 3 is less than a specific output which is set to be an output value or less of the fuel cell 1, while the storage battery 7 compensates the output to the load 3 if the power consumption of the load 3 exceeds the specific output. When the power consumption of the load 3 is less than the specific output of the fuel cell 1, charging/discharging of the storage battery 7 is suspended for a prescribed period so that the storage battery is opened in terms of circuit. During this period, an open-circuit voltage value of the storage battery is measured, and based on the relationship between an OCV value and an SOC value of the storage battery, the SOC of the storage battery is detected from the measured open-circuit voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage battery charge state detection method and a deterioration determination method in a power supply system using a storage battery and an independent power source such as a fuel cell.

[0002]

2. Description of the Related Art In recent years, fuel cell power generation systems have attracted attention from the viewpoint of efficient energy use. However, when attempting to generate power using only the fuel cell, the output response of the fuel cell is poor with respect to fluctuations in external load, so a storage battery is installed side by side with the power generation system, and this storage battery stores excess power of the fuel cell. A system for supplying a power shortage has been proposed. As a storage battery used in such a system, a lead storage battery, which has excellent economical efficiency, has a track record of reliability and safety, and has a established recycling system, is suitable.

In the conventional fuel cell power generation system, as shown in FIG. 4, D is provided between the output of the fuel cell 41 and the storage battery 42.
It has been proposed to provide a charger 43 configured by a C-DC converter or the like and capable of controlling the output from the fuel cell 41. When the output of the fuel cell 41 has a surplus with respect to the power consumption of the load 44, a part of the output from the fuel cell 41 is connected to the load 44 via the power conversion device 45, and The surplus output of 41 is stored in the storage battery 42 via the charger 43.

Further, the power consumption of the load 44 is the fuel cell 4
When the output exceeds the specific output set to be less than the maximum output of 1, the output from the storage battery 42 is supplied to the load 44 via the power conversion device 45. In such a power generation system, in order to efficiently store the surplus power of the fuel cell 41 in the storage battery 42, it is necessary to control the state of charge of the storage battery 42 (hereinafter referred to as SOC) in a low state of less than 100%. is there. This is because if the SOC of the storage battery 42 is constantly controlled to be close to 100%, the storage battery 42 will not be able to store surplus power and will be overcharged, which will shorten the life of the storage battery 42.

SO of a storage battery in such a system
The method of detecting C includes a method of detecting from the open circuit voltage of the storage battery (hereinafter referred to as OCV), a method of detecting from the internal resistance of the storage battery, and a detection from the amount of charge / discharge electricity obtained by integrating the charging / discharging current of the storage battery over time. Method is used.

Particularly, when a lead storage battery or a lithium secondary battery is used as the storage battery, the SOC of the storage battery and the OCV of the storage battery
Since there is a strong correlation with the above, the above method becomes an effective means when these storage batteries are used.
The above method is also an effective method, but by detecting an increase in internal resistance due to a decrease in sulfuric acid concentration of the electrolytic solution, secular change of the storage battery (decrease in electrolytic solution, deterioration of electrode grid and active material) (Changes in etc.) change the values, so it is necessary to correct them in some way. Further, in order to accurately measure the OCV of a storage battery, it is necessary to leave the storage battery in a non-loaded state after charging / discharging, but in the conventional fuel cell power generation system, the storage battery is constantly charged / discharged, and It is difficult to see the OCV of.

Further, in the above-mentioned method, if the SOC of the storage battery before accumulating the charging / discharging current is accurately grasped, it becomes possible to detect the SOC of the storage battery after that. However, when detecting the amount of charge and discharge electricity of the storage battery, a detector capable of performing accurate measurement in a wide measurement range is required in order to accurately detect the numerical value. At present, it is relatively easy to detect the problem of the accuracy of the detector, that is, the large value of the current and voltage, but it is difficult to detect the small value accurately, so It is difficult to detect SOC for a long time without error by only integrating.

Regarding the determination of the deterioration state of the lead acid battery,
Although there is a method of making a determination based on the discharge voltage value, an OCV value, and a measurement based on the internal resistance value of the storage battery, it is difficult to accurately determine the deterioration state of the storage battery only by these methods as in the case of detecting the SOC described above. Met.

When the SOC of the storage battery cannot be accurately detected, the SOC of the storage battery deviates from the proper range and the storage battery is deteriorated due to overcharging or insufficient charging causes a decrease in capacity, which causes the power generation system to function. There is a problem that it causes trouble. Further, when the deterioration of the storage battery cannot be accurately determined, appropriate maintenance and inspection such as replacement of the storage battery is not performed, resulting in a problem that the reliability of the power generation system is reduced.

[0010]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned problems, and in an electric power supply system having a storage battery attached to an independent power source such as a fuel cell, the SOC detection and deterioration determination of the storage battery can be performed accurately. It is intended to provide a method of doing well.

[0011]

In order to solve the above-mentioned problems, the invention according to claim 1 of the present invention comprises an independent power source and a storage battery to supply electric power to an external load, When the power consumption is less than the specific output set below the output value of the independent power supply, the independent power supply supplies the output to the external load while charging the storage battery, and when the power consumption exceeds the specific output. In the method for detecting the SOC of a storage battery used in a power supply system that supplements the output from the storage battery to an external load, the charging / discharging of the storage battery is stopped for a predetermined period at a time when the power consumption of the external load is less than the specific output, The OCV value of the storage battery is measured within a predetermined period, and the SOC of the storage battery used in the power supply system is detected based on the relationship between the OCV value of the storage battery and the SOC value of the storage battery. Shows a charging state detecting method of the battery used in the power supply system according to.

According to a second aspect of the present invention, an independent power source and a storage battery are provided to supply power to an external load, and the power consumption of the external load is set to an output value of the independent power source or less. When it is less than a specific output, the independent power source supplies an output to an external load while charging the storage battery, and when the power consumption of the external load exceeds the specific output, the output from the storage battery is supplemented to the external load. Along with, the SOC of the storage battery is controlled to be charged at less than 100%, the SOC is charged to 100% at predetermined time intervals, and a state of charge detection method for the storage battery used in a power supply system for overcharging is further provided. The SOC of the storage battery is obtained by integrating the charge / discharge electricity amount of the storage battery, and after the overcharge, the S
1 shows a method for detecting the state of charge of a storage battery used in a power supply system, which is characterized by setting an OC value to 100.

According to a third aspect of the present invention, an independent power source and a storage battery are provided to supply power to an external load, and the power consumption of the external load is set to an output value of the independent power source or less. When it is less than a specific output, the independent power source supplies an output to an external load while charging the storage battery, and when the power consumption of the external load exceeds the specific output, the output from the storage battery is supplemented to the external load. At the same time, a method for determining deterioration of a storage battery used in a power supply system, wherein the SOC of the storage battery is controlled to be less than 100%, the SOC is charged to 100% at predetermined time intervals, and further overcharged. When the power consumption of the load is less than the specific output, charging / discharging of the storage battery is stopped for a predetermined period, the OCV value of the storage battery is measured within the predetermined period, and the OCV value of the storage battery and the storage of electricity are stored. The first, which was determined from the relationship between the SOC value of
It is shown that the deterioration state of the storage battery is determined by comparing the SOC value of the storage battery and the second SOC value provided by integrating the charging / discharging current of the storage battery.

The invention according to claim 4 of the present invention is characterized in that a fuel cell is used as an independent power source in the method for detecting the state of charge of a storage battery used in the power supply system according to the structure of claim 1 or 2. It is a thing.

Further, the invention according to claim 5 of the present invention is characterized in that a fuel cell is used as an independent power source in a method for judging deterioration of a storage battery used in a power supply system according to the structure of claim 3. Is.

[0016]

1 is a block diagram showing the configuration of a power supply system to which the present invention can be applied.

The output of the fuel cell 1 as a stand-alone power source is connected to a power converter 2 (DC-AC converter) to supply the load 3 with necessary power. As the power conversion device 2, a DC-AC converter or a DC-DC converter is used according to the output required by the load 3.

A part of the output of the fuel cell 1 is connected to the fuel cell 1 via the backflow prevention diode 4, the charge control switch 5 and the charge quantity detecting means 6. When the power consumption of the load 3 is smaller than the specific output set to be less than the maximum output of the fuel cell 1, that is, when the output of the fuel cell 1 has a surplus or when the SOC of the storage battery 7 is increased, charging is performed. The control switch 5 is closed and a part of the output of the fuel cell 1 is charged in the storage battery 7. At this time, the charge electricity amount flowing from the fuel cell 1 to the storage battery 7 is detected by the charge electricity amount detecting means 6, and the information thereof is sent to the first SOC detecting means 8.

The output of the storage battery 7 is connected to the input of the power conversion device 2 through the discharge electricity amount detecting means 9 and the discharge control switch 10, the power consumption of the load 3 increases, and the output exceeds the specific output of the fuel cell 1. When the fuel cell 1 alone cannot follow the load 3, the discharge control switch 10 is closed and power is supplied from the storage battery 7 to the load 3 through the power converter 2. At this time, the discharge electricity amount flowing from the storage battery 7 to the power conversion device 2 is detected by the discharge electricity amount detecting means 9, and the information thereof is sent to the first SOC detecting means 8.

In the SOC detecting method for the storage battery used in the power supply system according to the first embodiment of the present invention, when the power consumption of the load 3 is equal to or lower than the specific output of the fuel cell 1,
Charging and discharging from the fuel cell 1 to the storage battery 7 is stopped for a predetermined period. In the example shown in FIG. 1, the charge control switch 5 and the discharge control switch 10 are opened. The OCV detecting means 11 detects the OCV of the storage battery 7 within this predetermined period.

The SOC is detected by the first SOC detecting means 8 by comparing this OCV value with a preset OCV-SOC relationship as shown in FIG. In such an SOC detection method, since the storage battery is intentionally opened in a period in which power supply from the storage battery is not required, an accurate OCV value can be obtained and the SOC detection accuracy can be improved. Further, at the timing when the storage battery 7 is opened, the fuel cell 1 has surplus electric power with respect to the load 3, so that stable supply of electric power from the fuel cell 1 to the load 3 can be performed.

Here, the period during which the storage battery is held in the open circuit state can be set, for example, between a few seconds and a few hundred seconds, as illustrated in FIG. Further, in FIG. 2, the rated capacity is 48 Ah at a nominal voltage of 12 V and a 10-hour rate discharge.
This is an example of a control valve type lead-acid storage battery of which the storage battery temperature is 25 ° C, but depending on the type and temperature of the storage battery, the OCV-
Since the SOC correlation changes, it is preferable to detect the storage battery temperature and correct the SOC value based on this temperature data.

Next, in the second embodiment of the present invention, SOC detection is performed by measuring the amount of charge and discharge electricity of the storage battery. The SOC of the storage battery 7 is detected by the second SOC detecting means 12 from the values of the charge electricity quantity and the discharge electricity quantity obtained by the charge electricity quantity detecting means 6 and the discharge electricity quantity detecting means 9.
To detect.

In the power supply system to which the present invention is applied, the SOC of the storage battery 7 is usually controlled to less than 100% in order to store the surplus power of the fuel cell 1 efficiently, but the SOC is always 100%. If it is controlled to be less than 1, the capacity deterioration of the storage battery 7 progresses. In particular, when a lead storage battery is used as the storage battery 7, lead sulfate, which is a discharge product, accumulates in the storage battery active material.

Although the accumulation of lead sulfate is eliminated by charging at a predetermined time interval, if the SOC is kept below 100%, the accumulated lead sulfate is fixed and the capacity does not recover even by charging. Therefore, the SOC of the storage battery 7 is raised to around 100% at a predetermined time interval,
Further, refresh charging is performed so that the storage battery capacity is overcharged.

In the present invention, the SOC value is reset to 100 after the refresh charge, which is the overcharge, and the integration of the charge / discharge electric quantity is restarted. According to the method of the present invention as described above, the accumulated error of the charge / discharge electric quantity measurement is eliminated every time refresh charging is performed, so that accurate SOC detection can be performed.

According to these aspects of the invention, since the SOC of the storage battery used in the power supply system can be accurately detected, the storage battery will not be overcharged or will fall into insufficient charge and the capacity will not be reduced, and the power supply The system can be operated stably.

The deterioration of the storage battery used in the power supply system according to the third embodiment of the present invention is determined by the SOC value detected by the above-described first embodiment (hereinafter referred to as the first S value).
Similarly to the OC value), the SOC value detected by the second embodiment described above (hereinafter referred to as the second SOC value).
Using.

The inventors of the present invention measure the OCV value of the storage battery, and determine the difference between the first SOC value detected from the OCV value and the second SOC value detected from the charge / discharge electricity of the storage battery. That is, it was found that the first SOC minus the second SOC (hereinafter referred to as ΔSOC) is closely related to the degree of capacity deterioration of the storage battery. In FIG. 3, the storage battery is the above-mentioned 12V4.
Control valve type lead-acid battery of 8Ah, storage battery temperature 25
It is a figure which shows the relationship of the discharge capacity (displaying the percentage with respect to initial discharge capacity)-(DELTA) SOC of a storage battery in the case of (degreeC).

In the present invention, based on the relationship illustrated in FIG. 3, the deterioration determining means 13 determines the capacity deterioration of the storage battery 7 from the ΔSOC value. More specifically, ΔSOC
When the value deviates from a certain range, the deterioration is judged, or as shown in FIG.
The degree of deterioration is determined based on the relationship between the C value and the storage battery capacity. The deterioration determination display can be performed using a display means such as a lighting lamp or a display. Then, according to such a capacity deterioration determination method, without discharging the storage battery,
The degree of deterioration of the storage battery can be accurately determined, and the user of the power supply system can perform maintenance and inspection work such as replacement of the storage battery based on the determination result.

[0031]

As described above, according to the present invention, since the SOC of the storage battery can be accurately detected in the power supply system in which the independent power source such as the fuel cell and the storage battery are combined, the deterioration of the storage battery can be suppressed. Therefore, the power supply system can be operated stably. Further, since the maintenance / inspection of the power supply system can be facilitated by accurately determining the deterioration state of the storage battery, the present invention is industrially extremely useful.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a power supply system to which the present invention can be applied.

FIG. 2 is a diagram showing a relationship between OCV, which is an open circuit voltage of a storage battery, and SOC.

FIG. 3 is a diagram showing a relationship between a storage battery discharge capacity and ΔSOC.

FIG. 4 is a block diagram showing the configuration of a conventional power supply system using a fuel cell.

[Explanation of symbols]

1,41 Fuel cell 2,45 Power converter 3,44 load 4 Backflow prevention diode 5 Charge control switch 6 Charge amount detection means 7,42 storage battery 8 First SOC detecting means 9 Discharge electricity amount detection means 10 Discharge control switch 11 OCV detection means 12 Second SOC detecting means 13 Deterioration determination means 43 charger

Continued front page    (72) Inventor Hiroyuki Jimbo             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F term (reference) 2G016 CB11 CB12 CB22 CB32 CC02                       CC06 CC07 CC12 CC23 CD09                       CE01 CE03                 5G003 AA05 BA01 DA07 DA18 EA05                       EA08 GB06                 5H030 AA06 AS03 AS18 BB08 BB22                       DD02 DD06 FF41 FF46

Claims (5)

[Claims] 1. An independent power source and a storage battery are provided to supply electric power to an external load, and when the power consumption of the external load is less than a specific output set below an output value of the independent power source, the independent power source is provided. The type power supply supplies an output to an external load while charging the storage battery, and when the power consumption of the external load exceeds the specific output, the charging state of the storage battery used in the power supply system that supplements the output from the storage battery to the external load. In the detection method, when the power consumption of the external load is less than the specific output, the charging and discharging of the storage battery is stopped for a predetermined period, the open circuit voltage value of the storage battery is measured within the predetermined period, and the open circuit voltage of the storage battery is measured. The state of charge of the storage battery used in the power supply system is characterized by detecting the state of charge of the storage battery used in the power supply system based on the relationship between the value and the state of charge value of the storage battery. State detection method. 2. An independent power source and a storage battery are provided to supply power to an external load, and when the power consumption of the external load is less than a specific output set below the output value of the independent power source, the independent power source is provided. The mold power supply supplies an output to an external load while charging the storage battery. When the power consumption of the external load exceeds the specific output, the output from the storage battery to the external load is supplemented and the state of charge of the storage battery is set to 100. A method of detecting the state of charge of a storage battery used in an electric power supply system that performs charge control at less than%, charges the state of charge of the storage battery to 100% at predetermined time intervals, and further performs overcharge, wherein the state of charge of the storage battery is The state of charge of the storage battery used in the power supply system, which is obtained by integrating the amount of charge and discharge electricity of the storage battery and sets the state of charge value to 100 after the overcharge. Detection method. 3. An independent power source and a storage battery are provided to supply electric power to an external load, and when the power consumption of the external load is less than a specific output set below an output value of the independent power source, the independent power source is provided. The mold power supply supplies an output to an external load while charging the storage battery. When the power consumption of the external load exceeds the specific output, the output from the storage battery to the external load is supplemented and the state of charge of the storage battery is set to 100. The charge state is controlled to be less than 1%, and the charge state is set to 1 every predetermined time.
A method for determining the deterioration of a storage battery used in a power supply system that charges up to 00% and further overcharges, wherein charging / discharging of the storage battery is stopped for a predetermined period when the power consumption of the external load is less than the specific output. Then, the open circuit voltage value of the storage battery is measured within the predetermined period, and the first charge state value obtained from the relationship between the open circuit voltage value of the storage battery and the charge state value of the storage battery and the charge / discharge current of the storage battery are integrated. A method for determining deterioration of a storage battery used in an electric power supply system, comprising: determining a deterioration state of the storage battery by comparing a second state-of-charge value provided in the storage battery. 4. The method for detecting the state of charge of a storage battery used in a power supply system according to claim 1, wherein a fuel cell is used as the independent power source. 5. The deterioration determination method for a storage battery used in a power supply system according to claim 3, wherein a fuel cell is used as the independent power source.