JP2012186877A - Battery state detector for photovoltaic generation battery system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photovoltaic generation battery system capable of achieving high precision and deterioration determination, and to provide a state detector therefor.SOLUTION: The present invention is a photovoltaic generation battery system that charges energy supplied from a solar cell panel into a charging lead battery and an auxiliary battery and supplies electric power to a load. Reception of electric power from the solar cell panel and supply of electric power to a load are implemented by an incidental battery and its excess and shortage are compensated for by charging and discharging the lead battery.

Description

  The present invention relates to a battery system that mainly uses electric energy converted from solar energy and a state detection device thereof.

  The power supply system using solar cells as the main energy source is highly expected as an independent power source for remote islands that do not have a large-scale electrical energy supply source such as hydroelectric power generation and thermal power generation.

  However, the above-described solar energy may be affected by periodic or unexpected fluctuations in the natural environment and may not be able to supply stable electrical energy. When the amount of sunshine decreases or disappears, such as in cloudy weather, rainy weather, and nighttime, the amount of power generated by a solar cell is significantly reduced or disappears compared to the time of sunshine. In order to mitigate the influence of this fluctuation, it is common to use a solar battery panel connected to a battery system. When rain or nighttime sunshine energy is not sufficiently supplied, electric energy is supplied from the battery system to the load. In such a battery system, an inexpensive lead battery is often used.

  On sunny days with plenty of sunshine energy, the lead battery is charged with the electric energy generated by the solar cells during the daylight hours. If sunny days continue, the lead battery will be full, but if you are not blessed with sunshine for a long period of time, the lead battery will be short of electricity and cause a power short. Therefore, it is important to manage power consumption in accordance with the remaining capacity SOC of the lead battery. The amount of load can be adjusted depending on the SOC level. Also, in electronic devices such as computers, it is desirable to save data on a hard disk or the like before a power short circuit occurs. For this reason, the SOC. It is important to know accurately. In addition, when the capacity of the lead battery is reduced due to deterioration of the service life, there is a problem that the amount of power that can be used is reduced. If the lead battery has deteriorated to the standard level, replace it with a new one. For this reason, it is desirable to accurately determine the deterioration of lead batteries. In addition, with respect to deterioration such as sulfation that can be expected to recover to some extent when recovery processing is performed, appropriate detection and implementation of recovery processing are desired.

  As described above, although there is a strong demand for accurately determining the remaining capacity SOC and the deterioration state of the lead battery system, it has not been sufficiently achieved in the past. In general, as a method of obtaining the remaining capacity of the lead battery, a method is used in which the fully charged state of the lead battery that has not deteriorated is set to SOC 100% and the discharged state is set to SOC 0%, and the space between them is divided at equal intervals by an electric quantity. However, in the case of a system using solar cells, the supplied electric energy largely fluctuates due to sunlight, so that it is difficult to charge with a constant current value or power value even on a clear day. Furthermore, since the daylight hours of the day fluctuate depending on the weather and season, it is difficult to charge the battery at a certain time every day.

  Conventionally, as a method for estimating the SOC of a battery, the SOC is set to 100% after full charge and the charge / discharge current in use is integrated to obtain a real-time SOC (hereinafter referred to as integrated SOC). In this case, as a condition for full charge, the determination condition is that a certain time elapses during CV charging or that the charging current becomes a certain value or less. Alternatively, a method of reducing the charging current stepwise, such as multi-stage charging, and determining based on the battery voltage has been used. However, in the case of sunlight, the charging time does not become constant due to problems such as sunshine hours, so that there is a problem that the SOC does not become constant when charging is completed at sunset.

  Also, the load varies greatly depending on the equipment used depending on the time of day. Therefore, the discharge current has changed greatly, and it has been difficult to accurately estimate the SOC from the discharge voltage of the battery. In addition, in order to obtain a real-time battery SOC (hereinafter referred to as integrated SOC), current integration is performed based on the SOC value reset at the time of full charge. However, there is a problem that current integration accuracy decreases if the current fluctuation of charge / discharge is large. there were.

  In addition, when there is a shortage of sunshine over a long period of time, the amount of charged electricity is insufficient and sulfation occurs. In this case, full charge is performed under certain conditions, and the subsequent state of charge is changed to OCV. You can check the occurrence of sulfation if you check it. However, there has been no example of applying such a function to a lead battery for photovoltaic power generation. This is because it is difficult to complete full charge under certain conditions. It is known that sulfation recovers by performing a deeper discharge or deeper charge than usual after detection, but unless it is based on such detection, sulfation of lead batteries cannot be suppressed, and a healthy lead battery is bothered deeply Exposure to discharge and overcharge wastes power and adversely affects the lifespan. Further, if the sulfation is not resolved even after the sulfation elimination process, it is desirable to display that the battery should be replaced. However, such a detection function has not been achieved in the past.

  On the other hand, in order to accurately determine the remaining capacity of the battery, Patent Document 1 discloses a method in which the battery is divided into a plurality of blocks, the discharge is performed for each block, and the remaining capacity is determined by the number of battery blocks that have not yet been discharged. Proposed. This utilizes the fact that it is difficult to estimate the SOC during charging or discharging when detecting the SOC of the battery, but it is easy to detect in the charging completed state or discharging completed state. However, in the circuit shown, only the discharge load is switched, and the charging circuits are connected in parallel, so that a battery that has been deeply discharged and a battery that has not been discharged are charged in parallel. Naturally, the discharged battery is preferentially charged, but the battery connected to the load is also reduced in voltage depending on the amount of current consumed by the load, and is charged by the power from the solar cell panel. For this reason, a battery that is not connected to a load does not always receive power for sufficient charging. Therefore, it is not always fully charged under certain conditions at sunset on a sunny day. It is difficult to estimate an accurate SOC if it is unknown how much the battery being charged has been charged. In other words, even when there is sufficient sunshine, the charging is not completed under a stable and constant condition, so the SOC estimation accuracy decreases. Further, since the electric power generated by the solar cell directly enters the battery, the fluctuation of the charging current is large, and there is a problem that sufficient accuracy cannot be secured even if the SOC during charging is calculated by integrating the amount of electricity. Furthermore, the method for determining the deterioration of the battery is not mentioned. Therefore, when the battery is deteriorated, it is difficult to accurately estimate the SOC.

  Patent Document 2 describes a method related to SOC and deterioration estimation of a vehicle battery that is repeatedly charged and discharged in a relatively high SOC region. The SOC is estimated by using the charge / discharge current, voltage, and temperature of the battery to determine the polarization. However, the deterioration of the deterioration is judged to include the SOC and the deterioration of the SOC and the deterioration of the battery. Are not distinguished. When the battery is deteriorated, it is determined as a decrease in SOC, and the deterioration determination is not substantially performed. In this method, full charge is not performed and deep discharge is not performed. 100% or SOC 0% cannot be reset, and in principle, accurate SOC estimation is difficult. The SOC is a level at which 50% and 70% can be distinguished. This level is sufficient when used for controlling a hybrid vehicle, but it cannot be said that the accuracy is sufficient for solar use. Again, there is no specific description about detecting battery deterioration.

  Patent Document 3 adopts a method in which a battery block is divided into a plurality of blocks and refresh charging is performed with a constant current and a constant voltage for each block. In this configuration, power is exchanged between the blocks, and a specific block is refresh-charged at regular time intervals. The purpose of this configuration is to extend battery life. In this method, the battery block that is refresh-charged is in a state close to 100% SOC, so that this block can be reset to 100% SOC. However, there is no specific description about this. At this time, if no load period is provided and the OCV is checked, sulfation or the like can be detected, but there is no description of providing the no load period. Further, depending on the circuit configuration, it is possible to alleviate fluctuations in the charge / discharge current of some battery blocks and improve the current integration accuracy, but there is no description touching on this matter. Therefore, although Patent Document 3 has a similar structure, the main point of the invention is to extend the life of the battery, and the battery SOC detection and life deterioration determination are not particularly performed. That is, there is no function for accurately detecting the SOC of the battery, and no deterioration determination is performed. The only similar point is the part where the battery is divided into a plurality of blocks and power is transferred between the blocks, and the battery is refreshed and charged. This is described in Patent Document 4 described later and is known at the time of filing of this patent. It can be judged that there was. Therefore, new technology with common contents cannot be found.

  Patent Document 4 clearly discloses a method of dividing a series battery mounted on an electric vehicle into a plurality of blocks and using the power of other blocks to perform equal charge or refresh charge of a specific block. . The frequency of performing uniform charging or refresh charging is performed by detecting that the voltage variation of the battery exceeds a certain time interval or a certain level, and does not detect battery deterioration or sulfation. Also, processing to match the SOC between blocks using the fact that the SOC after equalization is 100% to 0% is performed, but after the equalization, equalization is performed for the purpose of compressing the SOC variation between blocks. There is no description of performing SOC management by integrating electric quantity with reference to the SOC at the time.

  The equalization process is performed in a state where the IG of the vehicle is OFF and there is no current flowing in and out of the battery from the outside. This is a technique that cannot be used in a solar system or the like to which a load is continuously applied. In the case of sunlight, there is no time period during which the system pauses. Therefore, when refresh charging is performed by moving power between blocks, it is necessary to make a judgment based on the state of the battery. In other words, it is important to perform near the sunset when the amount of power stored in the entire system is the largest, but Patent Document 4 does not have such description.

  Further, after refresh charging, no load period is provided, OCV is not obtained, and battery sulfation or capacity deterioration is not detected. As described above, Patent Document 4 focuses on equalization between battery blocks or refresh charging, and SOC detection and deterioration detection are not performed.

JP-A-56-121338 Japanese Patent Laid-Open No. 2003-331931 JP 2009-261076 A JP-A-10-066267

  When trying to determine the SOC and life deterioration of the battery with such a conventional configuration, it is difficult to complete the charging of the lead battery under certain conditions, so it is difficult to reset the SOC to the reference point when the charging is completed Met. Some have been charged under certain conditions such as refresh charging, but the purpose is to refresh the battery to the last, and it is not the one that resets the SOC as a reference point for SOC integration. Furthermore, when resetting the SOC to the reference point, there is no configuration that measures OCV or CCV to determine battery sulfation, capacity degradation, or the like.

  Further, in order to obtain the normal SOC with high accuracy, it is necessary to reset the SOC obtained by integration about once a day. This is to eliminate the accumulated error of the current detector. However, for this purpose, it is desirable to correct the SOC by measuring the OCV and CCV once a day under certain conditions, but none have been implemented.

  In addition, when performing current integration, a large charge / discharge current as in the case of photovoltaic power generation causes an increase in integration error. However, there has been no conventional technique that positively smoothes the current and improves the current integration accuracy.

  In order to solve the above-described problems, an invention according to claim 1 of the present invention includes a solar cell panel that converts solar energy into electric energy, a power conversion device that has an input connected to the solar cell panel, and its power. An auxiliary battery connected to the output of the converter, a bidirectional power converter connected to the auxiliary battery via one terminal, a lead battery connected to the other terminal of the bidirectional power converter, It comprises a load connected to the auxiliary battery, a state detection device, and a display unit for displaying information on the state detection device.

  The entire system constituted by these is driven mainly by the power supplied from the solar cell panel, and there is no power transfer outside the system.

  The electric power generated by the solar panel is supplied to the secondary battery via the power converter. The secondary battery is composed of a lithium ion battery or the like, and uses a battery that has a smaller storage capacity than the main lead storage battery and that can input and output a large charge / discharge current in the normal operating temperature range. The capacity may be about 0.2 to 0.05 times that of the lead battery. In general, a lithium ion battery can take a larger charge / discharge current per capacity than a lead battery at room temperature. Although the secondary battery can be constituted by a lead battery, since it takes a long time to be used at a low SOC, it takes a long time for processing such as refresh charging, which is not desirable.

  The load is directly supplied with power from the auxiliary battery, but receives power from the solar battery panel via a power converter and from the lead battery via a bidirectional power converter.

  The state detection device directly receives power from the subordinate battery device, and measures the voltage, temperature, charge / discharge current of the lead battery, the voltage, temperature, charge / discharge current of the auxiliary battery, the power conversion device, and the bidirectional Means for controlling the power converter and means for controlling the load.

  Next, these basic operations will be described. At the beginning of the day and at midnight, a load current with an average rate of 1/75 to 1/100 C (relative to the capacity of the lead battery) flows into the load. Prioritize discharge of the auxiliary battery, and discharge the lead battery when the capacity of the auxiliary battery reaches the lower limit. At this time, the amount of electric power to be discharged is approximately equal to the amount of electric power consumed by the load, and the bidirectional power converter is adjusted so that the SOC of the auxiliary battery does not increase or decrease. In this state, even if the load greatly fluctuates, the auxiliary battery buffers so that fluctuations in the power supplied from the lead battery through the bidirectional power converter are alleviated.

  Next, when the sun rises, the solar panel starts power generation by sunlight. When the amount of power generation exceeds the amount of power consumed by the load, that amount is preferentially used for charging the lead battery. Lead batteries are charged during sunlight, while the amount of power generated exceeds the load consumption. When the SOC of the lead battery rises and the battery voltage exceeds the set value, CV charging starts. In CV charging, since the charging current is limited, surplus power is generated. The auxiliary battery is charged with this surplus power. When the charging of the auxiliary battery is completed, the output of the power converter connected to the solar cell panel is reduced, the charging of the auxiliary battery is stopped, and the CV charging of the load and the lead battery is performed. In this state, when the CV charging time of the lead battery elapses for a predetermined time or when the charging current decays below a predetermined current value, the lead battery charging is terminated and the output of the power converter connected to the solar cell panel is reduced. The solar panel power is only supplied to the load. The time for performing CV charging is approximately 5 hours. Usually sunset occurs before the 5 hour CV charge ends. In this case, in the present invention, the power of the auxiliary battery is used to continuously supply power to the load and CV charge of the lead battery. As a result, CV charging can be terminated under certain conditions. Further, even when the output of the solar cell panel is reduced due to the shade of the clouds during the sunshine hours, stable CV charging can be continued by supplying power from the auxiliary battery.

  The lead battery is fully charged at sunset because the lead battery SOC is maximized at that time on a clear day. By doing so, the capacity of the auxiliary battery can be kept small. It becomes. The state detection device controls the series of power converters, bidirectional power converters, and loads.

  When the amount of power generated by the solar panel after sunset cannot compensate for the power consumed by the load, the auxiliary battery starts discharging. At this time, as described above, if 5 hours of CV charging of the lead battery is not completed, CV charging power is also supplied by discharging the auxiliary battery. Discharge until the auxiliary battery reaches the lower discharge limit and complete CV charging of the lead battery as much as possible. When CV charging is not completed under predetermined conditions, it is determined that full charging has not been completed. Thereafter, the lead battery is discharged at 0.1 to 0.05 C for a certain period of time, and the power at that time is used to feed the load and charge the auxiliary battery. CCV is measured at the end of discharge. Thereafter, the load is supplied to the load with the auxiliary battery, the lead battery is kept open for 1 hour, and then the OCV is measured. The SOC is obtained by applying the OCV and CCV obtained in this way to the relational expressions of SOC and OCV and SOC and CCV obtained in advance. It is known that the SOC of a lead battery has a high correlation with the OCV, and this makes it possible to estimate the SOC with high accuracy. The reason for discharging for 1 hour after charging is to eliminate the influence of charging polarization. In order to eliminate the charge polarization, it is necessary to leave it for about 3 hours, but in order to eliminate the discharge polarization, it can be left for about 1 hour. If the discharge is not performed at 0.1 to 0.05 C for one hour, the charge polarization remains, and when the OCV is measured after one hour of rest, the accuracy of the obtained SOC is lowered. Similarly, the CCV when discharged for 1 hour at a constant load has a high correlation with the SOC. CCV may also be measured and used to estimate the SOC.

  If it is determined that the battery is fully charged, and the SOC obtained from the OCV and CCV matches the SOC after 1 hour of discharge after full charge and 1 hour of standing, the integrated SOC is reset.

  If they do not match, the SOC. When the SOC is larger than approximately 5% and the SOC obtained from the OCV or CCV is smaller, it is determined as sulfation, and a sulfation alarm is displayed on the display unit. Even in that case, the integrated SOC is reset with the SOC value obtained from OCV to CCV.

  Even when it is not determined that the battery is fully charged, the integrated SOC is reset with the SOC value obtained from the OCV to CCV. However, in this case, sulfation is not judged.

  Thereafter, each time the lead battery is charged / discharged, the amount of electricity is accumulated, and the accumulated SOC value is updated.

  After resetting the integrated SOC, power is supplied to the load while giving priority to discharging the auxiliary battery. When the auxiliary battery reaches the lower limit of the SOC, the lead battery is discharged, and control is performed so that the amount of electricity from the auxiliary battery is zero. The upper and lower limits of the SOC of the auxiliary battery are managed by the upper and lower limits of the voltage of the auxiliary battery and current integration. The amount of electricity remaining in the auxiliary battery has little effect on the overall SOC accuracy. This is because the capacity of the auxiliary battery is about 1/10 of the capacity of the lead battery.

  Thereafter, in this state, the SOC of the lead battery accumulates the discharge current and sequentially updates the accumulated SOC. As described above, the integrated SOC can be obtained with high accuracy by resetting the SOC value after CV charging of the SOC of the lead battery for a certain time. In addition, deterioration determination such as sulfation can be performed with high accuracy. The SOC is also a value corrected for the influence of sulfation (a value taken into account).

  The invention according to claim 2 of the present invention takes the same form as that of claim 1 in the configuration of the apparatus. If the amount of sunshine during the day is insufficient in terms of operation and sufficient power for charging the lead battery cannot be obtained, charging cannot be completed in a certain charging completion state as shown in claim 1. . When the sunset is reached as it is, it is difficult to determine the SOC by the OCV or CCV. When obtaining SOC by normal current integration, an electric current of ammeter error × 24 hours becomes an error after 1 day. Since the maximum charging current during normal sunshine is equivalent to 0.1C with a lead battery, if an ammeter of this range is used and the accuracy is 1%, the error of one day is 0.1 × 1 × 24 = 2. 4%. Therefore, when the accuracy of about 10% is targeted, it is desirable to reset the SOC in about 24 hours. Therefore, it is desirable to measure the OCV or CCV and reset the integrated SOC even when the full charge is not completed on the day when the sunshine is insufficient. Therefore, if the full charge is not achieved after the sunset time, the auxiliary battery is discharged until the discharge lower limit is reached, and then the lead battery is discharged at 0.1 to 0.05 C for a certain time. At that time, the power is supplied to the load and the auxiliary battery is charged. CCV is measured at the end of discharge. Thereafter, the load is supplied with an auxiliary battery, the lead battery is opened and maintained for 1 hour, and then the OCV is measured. The SOC is obtained by applying the OCV and CCV obtained in this way to the relational expressions of SOC and OCV and SOC and CCV obtained in advance. The accumulated SOC is reset with the obtained SOC. The detection of the sunset time may be determined when the output of the solar cell panel becomes almost zero, or may be determined by a clock in the area where the equipment is installed. By adopting such a configuration, it is possible to reset the accumulated SOC with OCV to CCV within 24 hours, and to correct the current accumulated error. In this case, since the charging is not completed under a certain condition, the battery deterioration determination such as sulfation is not performed.

  The invention according to claim 3 of the present invention has the same configuration as that of claim 1 described above. The operation is the operation of claim 2 when the amount of sunshine during the day is insufficient and sufficient power for charging the lead battery cannot be obtained, but when the non-sunlight continues, the operation of claim 3 It becomes operation. In this case, the SOC of the lead battery may decrease, and eventually a complete discharge state may be reached. In this case, the SOC is obtained with high accuracy immediately before reaching the complete discharge. When the voltage per unit cell of the lead battery reaches approximately 1.85 V, the lead battery is discharged at 0.1 to 0.05 C for 1 hour. At that time, the power is supplied to the load and the auxiliary battery is charged. CCV is measured at the end of discharge. Thereafter, the load is supplied with an auxiliary battery, the lead battery is opened and maintained for 1 hour, and then the OCV is measured. The OCV and CCV obtained in this way are applied to the relational expressions of SOC and OCV and SOC and CCV obtained in advance, and the SOC is obtained. The accumulated SOC is reset with the obtained SOC. As a result, the SOC can be obtained with high accuracy at the end of discharge.

  The invention according to claim 4 of the present invention has the same configuration as that of claim 1 described above.

  After fully charging the lead battery under the conditions described above, constant current discharge and load release were performed, and the SOC obtained from the obtained OCV and CCV was obtained in advance after full charge and constant current discharge and load release were performed. When the estimated SOC value decreases by 5% or more, the sulfation occurrence is displayed on the display unit, the CV charging time is extended at the next full charge, or the power of the lead battery is changed from midnight. Used to charge the auxiliary battery and feed the load, just before sunrise, raise the SOC of the auxiliary battery to discharge the lead battery deeper and eliminate sulfation. The OCV and CCV values obtained by constant current discharge after full charge and release of the load may be recorded in a time series from the beginning of the lead battery and may be determined as sulfation when the value is reduced by 5% with respect to the initial value. With this configuration, the sulfation of the lead battery can be detected, and if it is a mild sulfation, it can be eliminated.

  The invention according to claim 5 of the present invention adopts the same structure as that of claim 1. With this configuration, power for charging is provided by power converted from sunlight by the solar cell panel. Electric power is consumed by the load. In a clear sky with no clouds, the solar panel supplies power that is consistent with the solar altitude, but in reality it is affected by clouds and the output changes at intervals of several tens of seconds even in clear sky. On the load side, power is generally consumed at the maximum load of about 5 times the average load, although it depends on the use situation. The charging current greatly fluctuates due to such fluctuations in load and power generation capacity. In other words, even on a clear day, charging becomes impossible due to the condition of the load and the state of the clouds, and the power generation amount of the solar cell exceeds the consumption amount due to the addition. In order to integrate charging / discharging currents that vary greatly in this way, it is necessary to measure and integrate the currents with high-speed sampling corresponding to the variations. However, since a highly accurate current system generally has a long sampling time, there is a limit to shortening the sampling time. When the current is integrated at a constant accuracy and a constant sampling rate, the smaller the fluctuation, the lower the error. In the present invention, charging power and discharging power are supplied from the sub-battery, and the charging / discharging current of the sub-battery is monitored and averaged in units of several minutes. By charging and discharging the lead battery while changing the setting in units of several minutes using this average current, it becomes possible to charge and discharge with a current with little fluctuation with respect to time. As a result, the current integration accuracy can be improved. At this time, the current monitoring of the sub-battery does not need to grasp the SOC with high accuracy, so high-speed sampling is not necessary. The sub-battery performs rough management of the SOC limit.

  The invention according to claim 6 of the present invention is configured such that the capacity of the auxiliary battery is 1/5 to 1/120 with respect to the capacity of the lead battery. The power storage system of a normally independent photovoltaic power generation system is designed to be able to supply power for 3 to 5 days without sunshine. As a result, the average load is about 1/72 to 1/120 C of the capacity of the lead battery. On the other hand, when a lead battery is fully charged, it takes about 5 hours from the start of CV charging. At that time, the amount of electricity required for charging is about 10% of the capacity. Therefore, if there is an amount of electricity equivalent to 1 / 5C, which is 5/72 for power supply to the load for 5 hours and 1/10 for CV charging, the power supply to the load for 5 hours, CV charging is possible. This calculation is performed when CV charging is performed for 5 hours after sunset. Actually, the CV charging is often started before sunset, and charging after sunset is shorter than 5 hours. Therefore, there are cases where a smaller capacity, about 1/20, can be covered. When the load is concentrated at night, it is possible to perform stable CV charging with an auxiliary battery having a smaller capacity. In order to create no load for 1 hour after constant current discharge, the capacity of about 1/72 to 1/120 can be provided. Therefore, it is desirable to set within the range of 1/5 to 1/120.

  According to the present invention, the lead battery can always be charged under certain conditions on a clear day, so that the accumulated SOC can be accurately reset, and deterioration due to sulfation can be detected by accurately measuring OCV to CCV, and an alarm is issued. And a refresh operation can be performed. In addition, the OCV to CCV is always measured once a day, and the accumulation of ammeter errors is suppressed by measuring the OCV to CCV at the end of discharge. In addition, the charge / discharge current of the lead battery can be averaged with little fluctuation with time, so the accuracy of electric quantity integration is improved, and the battery status of the battery system for photovoltaic power generation that can detect SOC with high accuracy and is highly convenient. Equipment can be provided.

Configuration diagram of a battery system for photovoltaic power generation using the battery state detection device of the present invention Configuration diagram of a conventional solar power battery system used for comparison The figure which shows the time of fine weather day, cloudy day, rainy day and the state of sunshine The figure which shows the daily power consumption pattern of general household The figure which shows the voltage and charge / discharge current of the lead battery of the example and the conventional example with a sunny day SOC 90% start The figure which shows the voltage and charge / discharge current of the lead battery of the example and the conventional example with 70% start on a sunny day Cloudy day Figure showing the voltage and charge / discharge current of the lead battery of Example and conventional example at SOC 90% start The figure which shows the relationship between OCV thru / or CCV and SOC The figure which shows the voltage and charge / discharge current of the lead battery of the example in the rainy day SOC 90% start and the conventional example Figure showing the change in accumulated SOC when the equipment is in operation for 4 days The figure which shows the voltage and charge / discharge current of the lead battery of the example in the rainy day SOC 50% start and the conventional example The figure which showed change of OCV and SOC at the time of SOC reset in full year evaluation A diagram showing the change over time in the charging current of a lead battery during sunshine

  Hereinafter, a preferred example of an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a preferred configuration of the power supply system of the present invention. In FIG. 1, a solar cell panel 1 is used as an energy conversion unit that converts natural energy into electrical energy. Further, the power line from the solar cell panel 1 is connected to the auxiliary battery 3 via the power converter 2. The auxiliary battery 3 is connected to the load 5 through the DC / AC converter 4. The load 5 is composed of an electronic load device, and in the case of the present embodiment, the load 5 is set so as to consume power in a preset power consumption pattern of a general household. The power consumption pattern is a 24-hour pattern assuming a summer day. Similarly, a lead battery 7 is connected to the auxiliary battery 3 via a bidirectional power converter 6. Charging / discharging current detection shunts 8 are respectively provided on the current lines of the auxiliary battery and the lead battery. The controller 10 is supplied with electric power from the auxiliary battery 3 through a current line, measures the voltage of the auxiliary battery 3 and the lead battery 7, and the charge / discharge current through the shunt 8, and based on these, the power converter 2 Control of the bidirectional power converter 6 and the DC / AC converter 4 and information on display are sent to the display 9. In order to transmit and receive information, these devices are connected by signal lines.

  The lead battery 7 is a seal-type lead battery for cycle use that is generally used in solar light applications, and is constituted by connecting 10 pieces of a model having a nominal voltage of 12 V capacity of 500 Ah in series. Similarly, the auxiliary battery used was a unit in which a lithium ion battery having a nominal voltage of 120 V and 50 Ah was integrated with a safety control circuit. The power converter 2 is composed of a DC / DC converter and can adjust the output power based on a signal from the controller. As the solar cell panel 1, an open-circuit voltage 200 V output 6 kW and a built-in reverse current prevention diode were used. The bidirectional power converter 6 has a built-in DC / DC converter capable of switching polarity in both directions, and receives a signal relating to which direction power is supplied from the outside and how much power is converted. Then, power conversion is performed based on the received signal and power is sent to the auxiliary battery side, or power is sent to the lead battery side. As the DC / AC converter, a general commercial product is used. The DC / AC converter 4 is configured to be able to input an ON / OFF signal from the outside. When the controller issues an OFF signal in order to prevent the auxiliary battery from being overdischarged, the controller accepts the DC / AC conversion. When ON, power is supplied to an external AC appliance. The load is originally composed of home appliances in the home, but in this embodiment, an AC input electronic load device is used so that the load can be consumed as much as possible and the operation can be confirmed. This electronic load device is a method of consuming electric power determined by a 24-hour program, and an ordinary household power consumption pattern is set as a program.

  The controller 10 measures the voltage of the lead battery, the voltage of the auxiliary battery, the shunt 8 for measuring the charge / discharge current of the lead battery, and the voltage of the shunt 8 for measuring the charge / discharge current of the auxiliary battery. A microcomputer is mounted inside, and the voltage signal is converted to digital by the AD converter of the microcomputer, and the digital information is processed inside the microcomputer. A clock function is installed inside the microcomputer, and the time integration of the current is performed, and information on the battery stored in advance, for example, data on the relationship between the battery SOC and OCV, the relationship between the SOC and CCV, etc. The SOC is estimated. Based on these pieces of information, the controller 10 instructs the power converter 2 on the amount of power conversion via the communication line. In accordance with this communication information, the power converter 2 adjusts the amount of power flowing from the solar cell panel to the auxiliary battery. Similarly, the bidirectional power converter 6 receives information on the conversion direction and the amount of converted power from the controller, and charges or discharges the lead battery according to this information. The DC / AC converter supplies power to the load while receiving power from the auxiliary battery according to the ON / OFF instruction information of the controller. The display unit 9 displays information from the controller 10. The contents to be displayed are the SOC and deterioration state of the battery, whether the lead battery is currently being charged, discharged or opened, the SOC of the auxiliary battery, and the like. In addition, the balance of the amount of power generation and discharge per day, the change with time of SOC, the past history, the time when the refresh charge was performed, and the like are displayed.

  Next, FIG. 2 shows a conventional example used for comparison. The conventional example includes a solar cell panel 1, a power converter 2, a lead battery 7, a DC / AC converter 4, a load 5, a controller 10, and a display unit 9. The function of each component is almost the same as that of the embodiment, but the function is simpler than that of the controller 10 alone. This is because there are no bidirectional power converter and auxiliary battery as components. In addition, the function of the display device is reduced, but the basic configuration is the same as the embodiment. The difference between these functions and the embodiment will be described in detail later.

  Next, FIG. 3 shows a typical sunlight state of sunlight when evaluated in Examples and Conventional Examples. The measured value was measured with a sunshine meter attached under the same conditions as the solar cell panel. FIG. 3A shows data on a sunny day, FIG. 3B shows data on a cloudy day, and FIG. 3C shows data on a rainy day. Electric power corresponding to this sunshine pattern is generated in the solar cell panel.

  FIG. 4 shows a typical household power consumption pattern on a summer day. This pattern was set as a model pattern in the electronic load device used for evaluation.

  FIG. 5 shows the lead-acid battery SOC. Shows the result of measuring the behavior on a clear day with 90% set to 90%. (A) is the voltage of a lead battery, (b) is the charge / discharge current of a lead battery. In the figure, a solid line indicates an example, and a broken line indicates a conventional example.

  First, examples will be described. In FIG. 5, the time indicates the elapsed time from 12:00 am (5-A). At dawn, the load is discharged until 7 o'clock (5-B). Since priority is given to discharging the auxiliary battery at night, the SOC of the auxiliary battery reaches the lower limit in this state. The lead battery is discharged through the bidirectional power converter so that the auxiliary battery is no longer discharged. The integrated SOC of the lead battery integrates the discharge current of the lead battery and updates its value sequentially.

  Thereafter, power is supplied from the power converter 2 to the auxiliary battery side at sunrise (5-B). When the amount of power generation exceeds the power consumed by the load, the SOC of the auxiliary battery increases, but the lead battery is preferentially charged so that the SOC does not change. This adjustment is performed by setting the output of the bidirectional power converter 6 to the lead battery side and adjusting the amount of power. The electric power generated by the solar panel is used to charge the load and lead battery. Around noon (5-C) lead battery voltage reaches the upper limit of 145V and enters CV charging. At this time, in this embodiment, the controller adjusts the output of the bidirectional power converter 6 so that the voltage of the lead battery is maintained at 145V. Meanwhile, the power converter 2 supplies the power from the solar cell panel to the auxiliary battery side to the maximum extent. In this state, surplus power is charged by the auxiliary battery. During CV charging, the integrated SOC is updated with the integrated value of the amount of charged electricity in consideration of the charging efficiency. A timer is started after entering CV charging, and CV charging is completed when 5 hours have elapsed (5-D), and the controller throttles the output of the bidirectional power converter to open the lead battery. In this state, the lead storage battery is determined to be fully charged, and the integrated SOC is reset at 100%.

  Thereafter, when there is sufficient power from the solar panel, power is supplied to the load and the auxiliary battery is charged, and when the SOC of the auxiliary battery reaches the upper limit, the output of the power converter 2 is reduced and only power is supplied to the load. .

  When sunshine decreases and the amount of power generation falls below the load (5-F), the auxiliary battery is discharged and power supply to the load is started.

  When the SOC of the auxiliary battery approaches the lower limit (5-G), start the bidirectional power converter, discharge the lead battery at the 0.1C rate for 1 hour, charge the auxiliary battery with that power, and supply power to the load . This state is maintained for 1 hour, and CCV is measured at the end (5-H).

  After that, the power of the load is supplied from the auxiliary battery, and the lead battery is brought into a no-load state. This state is maintained for 1 hour (5-I). Finally, the OCV is measured.

  The integrated SOC is compared with the SOC obtained from the OCV or CCV. If the deviation is large, it is determined as sulfation and displayed on the display unit. Regardless of the determination, the integrated SOC is reset to the SOC value obtained from the OCV to CCV. After that, power is supplied to the load with the auxiliary battery, discharged to the lower limit, and then supplied from the lead battery. The accumulated SOC is sequentially updated by accumulating the charge / discharge current.

  The above operation is repeated as a day operation. In the example, the battery was removed after 24 hours and discharged at 0.2 C using a constant current discharge device, and the remaining capacity was confirmed. Accumulated SOC. Was 88%, and the capacity of the lead battery was 89%, indicating a very close value.

  In this example, since a new lead battery was used, the difference between the SOC obtained from the OCV or CCV and the accumulated SOC was less than 2%. As a result, a deviation of 10% was found in the battery in which sulfation was generated. The results are shown in FIGS. 8 (a) and 8 (b). a is a new article and b is sulfated. It can be seen that even under similar charging conditions, a difference can be confirmed in OCV and CCV. Thus, it was found that the occurrence of sulfation could be confirmed.

  Next, the operation of the conventional example in the sunny day lead-acid battery SOC 90% will be described with reference to FIG. At 12:00 am (5-A), the lead battery is discharged and power is supplied to the load. The discharge current is integrated and the integrated SOC is corrected. Thereafter, with the sunrise (5-B), the charging current increases and the lead battery voltage also increases. When the lead battery voltage rises to 145V, CV charging starts. During CV charging, the duty of the power converter 2 is throttled and adjusted. Therefore, the output of the solar cell panel is reduced. CV charging continues while the generated power of the solar panel exceeds the power required for CV charging + the power of the load. At the time of 5-E, the output of the solar cell panel decreases, and it becomes impossible to cover the power for CV charging, and CV charging is terminated. At that time, the integrated SOC is reset to 100%. Thereafter, power is supplied to the load by the power of the lead storage battery. The integrated SOC is also corrected sequentially with the integrated value of the charge / discharge current. At the time of 24 hours, the lead battery was removed, and discharge and remaining capacity were confirmed using a constant current power supply. The integrated SOC was 83%, and the value obtained from the discharge test was 86%. Since the CV charging time is long, the actual SOC becomes a high value.

  FIG. 6 shows the result of measuring the behavior on a clear day with the SOC of the lead battery set to 70% in both the example and the conventional example. (A) is the voltage of a lead battery, (b) is the charge / discharge current of a lead battery. In the figure, a solid line indicates an example, and a broken line indicates a conventional example.

  First, examples will be described. In FIG. 6, the time indicates the elapsed time from 12:00 am (6-A). At dawn, discharge is caused by the load until around 7 o'clock (6-B). Thereafter, the operation of each component is equivalent to that of the SOC 90% shown in FIG. 5 until the lead battery voltage reaches the upper limit of 145V and starts CV charging at around 14:00.

  The behavior during CV charging is different between the SOC 70% start and the SOC 90% start. The amount of sunshine starts decreasing before 5 hours have passed for the CV charging end condition. Around 17:00 (6-E), the amount of power generated by the solar panel falls below the load consumption. CV charging has already been performed for about 3 hours, and excess power during that time is stored in the auxiliary battery. Therefore, for the remaining 2 hours, the power of the auxiliary battery is used to continue CV charging and to supply power to the load. When the timer reaches 5 hours (6-D), the CV charging is completed and the integrated SOC of the lead battery is reset to 100%. At this time, since the SOC of the auxiliary battery is lowered, the bidirectional power converter is started, the lead battery is discharged at a 0.1 C rate for 1 hour, the auxiliary battery is charged with the electric power, and power is supplied to the load. This state is maintained for 1 hour, and CCV is measured at the end (6-H). Thereafter, the load is supplied from the auxiliary battery, and the lead battery is left unloaded and maintained for 1 hour (6-I). Finally, the OCV is measured.

  As in the case of the SOC of 90%, the integrated SOC is compared with the SOC obtained from the OCV or CCV. If the deviation is large, it is determined as sulfation. Regardless of the determination, the integrated SOC is reset to the SOC value obtained from the OCV or CCV.

  After that, power is supplied to the load with an auxiliary battery, and when discharged to the lower limit, power is supplied from the lead battery. The accumulated SOC is sequentially updated by accumulating the charge / discharge current. The above operation is repeated as a day operation. In the example, the battery was removed after 24 hours and discharged at 0.2 C using a constant current discharge device, and the remaining capacity was confirmed. The display of the integrated SOC is 85%, and the capacity obtained as a result of discharging the lead battery is almost the same at 85%.

  Next, the operation of the conventional example in a sunny day lead-acid battery SOC 70% will be described. The behavior is almost the same as in the case of SOC 90%, but the start time of CV charging is delayed because the started SOC is lower. Therefore, the time for CV charging is 6.3 hours to 2.8 hours. At the time of 24 hours, the SOC display was 85%, the capacity as a result of discharging was 80%, and the deviation was large.

  FIG. 7 shows the result of measuring the behavior on a cloudy day with the SOC of the lead battery set to 90% in both the example and the conventional example. (A) is the voltage of a lead battery, (b) is the charge / discharge current of a lead battery. In the figure, a solid line indicates an example, and a broken line indicates a conventional example.

  First, examples will be described. In FIG. 7, the time indicates the elapsed time from 12:00 am (7-A). At dawn, until around 7 o'clock (7-B), a load is discharged. Thereafter, the lead battery voltage reaches the upper limit of 145 V at about 13:00 (7-C) and enters CV charging, but during this time, the behavior is almost the same as in the case of SOC 90% shown in FIG. The reason for entering the CV charge later is that the sunshine condition is not good.

  The behavior after CV charging is different from that on sunny days. Sunlight is blocked by the clouds while the CV charging end condition of 5 hours has not elapsed, the power from the solar cell panel is reduced, and the power for maintaining the CV charging is insufficient. However, since the auxiliary battery is charged during CV charging, the electric power is used to continue CV charging and supply power to the load. In this way, 5 hours of CV charging is completed in 7-D. At this time, since the SOC of the auxiliary battery is lowered, the bidirectional power converter is started, the lead battery is discharged at a 0.1 C rate for 1 hour, the auxiliary battery is charged with the electric power, and power is supplied to the load. This state is maintained for 1 hour, and CCV is measured at the end (7-H).

  Thereafter, the load is supplied from the auxiliary battery, and the lead battery is left unloaded and maintained for 1 hour (7-1). Finally, the OCV is measured.

  As in the case of a sunny day, the accumulated SOC is compared with the SOC obtained from the OCV to CCV, and when the deviation is large, it is determined as sulfation. Regardless of the determination, the integrated SOC is reset to the SOC value obtained from OCV to CCV. After that, power is supplied to the load with an auxiliary battery, and when discharged to the lower limit, power is supplied from the lead battery. The accumulated SOC is sequentially updated by accumulating the charge / discharge current. The above operation is repeated as a day operation. In the example, the battery was removed after 24 hours and discharged at 0.2 C using a constant current discharge device, and the remaining capacity was confirmed. The display of the integrated SOC is 85%, and the capacity obtained as a result of discharging the lead battery is almost the same at 85%.

  Next, the operation of the conventional example in a lead battery SOC 90% will be described on a cloudy day. The behavior is almost the same as in the case of SOC 90%, but it is interrupted many times during CV charging because of insufficient sunshine. When the final CV charging is completed (7-E), the integrated SOC is reset to 100%, and thereafter, the charging / discharging current is integrated to correct the integrated SOC. When 24 hours passed, the SOC display was 80%, and the capacity as a result of discharging was 87%, showing a large deviation. This is probably because the conventional example did not determine that CV charging was completed, and calculated the SOC only by integration. That is, it is considered that CV charging was interrupted due to sunlight conditions, and the battery started to discharge frequently.

  In addition, the figure of the relationship which calculates | requires SOC from OCV and CCV used in the present Example is shown in FIG. This figure shows that the lead battery used in the example was fully charged, discharged at 0.1C constant current for 1 hour, paused for 1 hour, repeatedly measured to near SOC 0%, and obtained OCV and CCV with respect to the SOC. And plotted.

  As described above, it is possible to stabilize the SOC when the CV charging is completed by minimizing the influence of the change in the weather and the change in the start SOC on the CV charging time. It was possible to reset, and the relationship between the SOC and OCV or CCV without sulfation was obtained in advance, and the occurrence of sulfation could be detected by comparing the accumulated SOC during operation with OCV or CCV.

  FIG. 9 shows the results of measuring the behavior on rainy days with the SOC of the lead battery set to 90% for both the example and the conventional example. (A) is the voltage of a lead battery, (b) is the charge / discharge current of a lead battery. In FIG. 9, the solid line indicates the embodiment, and the broken line indicates the conventional example.

  First, examples will be described. In FIG. 9, the time indicates the elapsed time from 12:00 am (9-A). Discharge due to the load occurs until dawn and around 10:00 (9-B). This is because there is little direct incidence of sunlight due to rain. Incidentally, in rainy weather, the sunshine intensity is about 1/10 of a sunny day. This is because the charging current peaked around 12:00, but there was a cloud break.

  Thereafter, the lead battery voltage did not reach the upper limit of 145V and did not enter CV charging. At about 10 o'clock (9-G) when 24 hours have passed since the previous integrated SOC reset, the SOC of the auxiliary battery has reached the lower limit. Here, the bidirectional power converter is activated, the lead battery is discharged at a 0.1 C rate for 1 hour, the auxiliary battery is charged with the electric power, and the load is supplied with power. CCV is measured at the end of the one hour discharge (9-H). Thereafter, the load is fed from the auxiliary battery, and the lead battery is left unloaded for 1 hour (9-I). The OCV is measured at the last timing of this one hour no-load state. Then, the integrated SOC is reset to the SOC value obtained from OCV to CCV. After that, power is supplied to the load with an auxiliary battery, and when discharged to the lower limit, power is supplied from the lead battery. The integrated SOC is corrected by sequentially integrating the charge / discharge current. The above operation is repeated as a day operation.

  Next, the operation of a conventional example in a lead battery SOC 90% on a rainy day will be described. Since the sunshine is less than 1/10 compared to a sunny day, you will not enter CV charging. The integrated SOC was only corrected with the integrated value of the charge / discharge current without being reset.

  The above is an explanation about the operation in the rainy weather of the example and the conventional example. Using the lead battery adjusted to SOC 90%, the device was operated in a pattern of sunny day → rainy weather → rainy weather → sunny weather, and the behavior of accumulated SOC was examined. The results are shown in FIG. (A) is a present Example, (b) is a prior art example. In this example, after the prescribed 5 hour CV charge, the accumulated SOC can be reset by OCV to CCV is “◯”, and the point where the 5 hour CV charge was not completed but was reset by OCV to CCV is “△”. It shows with. The conventional example is reset only when CV charging is completed, and the point is indicated by “◯”. When the experiment was completed, the lead battery was removed and the remaining capacity was confirmed by constant current discharge. As a result, the results were 90% for the example and 91% for the conventional example. The final SOC shift is not large in both the conventional example and the example. However, the accumulated SOC. From the movements at the time of resetting and the movements at the time of resetting, it can be seen that there is a large deviation in the accumulated SOC in the conventional example because it cannot be reset on rainy days. Therefore, the result is that the deviation is greatly corrected on the fourth sunny day. As described above, it can be seen that the accuracy can be improved by resetting the integrated SOC by OCV to CCV every 24 hours without CV charging.

  FIG. 11 shows the result of measuring the behavior on a rainy day with the SOC of the lead battery set to 50% for both the example and the conventional example. (A) is the voltage of a lead battery, (b) is the charge / discharge current of a lead battery. In the figure, a solid line indicates an example, and a broken line indicates a conventional example.

  First, examples will be described. In FIG. 11, the time indicates the elapsed time from 12:00 am (11-A). Discharge due to the load occurs until dawn and around 10:00 (11-B). The charging current peaked around 12:00, but there was some sunshine.

  Thereafter, the lead battery voltage never reaches the upper limit of 145V and does not enter CV charging. At 11-G when the battery voltage becomes 121V or less, the SOC of the auxiliary battery reaches the lower limit. Here, the bidirectional power converter is activated, the lead battery is discharged at a 0.1 C rate for 1 hour, the auxiliary battery is charged with the electric power, and the load is supplied with power. CCV is measured at the end of the one hour discharge (11-H). Thereafter, the load is supplied from the auxiliary battery, and the lead battery is left unloaded and maintained for 1 hour (11-I). The OCV is measured at the last timing of this one hour no-load state. Then, the integrated SOC is reset to the SOC value obtained from OCV to CCV. After that, power is supplied to the load with an auxiliary battery, and when discharged to the lower limit, power is supplied from the lead battery. The integrated SOC is corrected by sequentially integrating the charge / discharge current.

  Next, on a rainy day, lead battery SOC. The operation of the conventional example at 50% will be described.

  Since the sunshine is less than 1/10 compared to a sunny day, you will not enter CV charging. The integrated SOC was only corrected with the integrated value of the charge / discharge current without being reset.

  Thereafter, the lead battery was removed when 26 hours passed, and 0.2 C was discharged with a constant current discharger to check the remaining capacity.

  As a result, Example 25%, Conventional Example 20%, and Discharge Electricity 26%. Thus, it was found that when the lead battery voltage is lowered, the SOC can be obtained with high accuracy by correcting the integrated SOC by the OCV to CCV.

  FIG. 12 shows changes with time in the OCV and SOC reset values in the two cases of the present embodiment. The experiment was conducted for about one year under normal sunshine conditions, and the OCV measured after full charge during that period and the SOC determined from the values are shown in a and b, respectively. In the case of Example A, refresh charging is performed when the SOC decreases by 5%. In refresh charging, the CV charging time is normally 5 hours, but the time is extended as long as the capacity of the auxiliary battery permits. As a result, although depending on the sunshine conditions, CV charging can be performed for about 7 hours. As a result, it can be seen that in Example A, OCV and SOC are recovered. In particular, it can be seen that Example B which does not perform refresh charging has not recovered. As described above, since sulfation can be detected and solved by extending the charging time, it is possible to accurately obtain the SOC corrected for the influence of sulfation, and to eliminate sulfation appropriately. As a result, the convenience of the lead battery was improved.

  FIG. 13 shows the charge / discharge current of the lead battery of the present invention and the conventional example. The data shows the part where there was a change in sunshine during the daytime. Under conventional conditions, the current changes greatly with time, and the current must be measured with a sampling time of several seconds or less in order to obtain an accurate integrated value. However, in this embodiment, it can be seen that there is no problem with sampling at a level of several minutes. In general, it is necessary to measure the current with high accuracy for such electric quantity integration. To increase the sampling speed, it is necessary to improve the AD converter grade, and it is also necessary to provide a dedicated noise filter or the like. In the present embodiment, it was possible to cope with the AD level of the microcomputer in the embodiment, but in the conventional example, a dedicated AD converter chip and a noise filter were required, and the cost of the current measurement portion was about 10 times higher.

  According to the present invention, the SOC and deterioration state of the lead battery used in the photovoltaic power generation system are accurately grasped and displayed, and refresh charging is performed at an appropriate timing, thereby improving the convenience of the lead battery.

DESCRIPTION OF SYMBOLS 1 Solar cell panel 2 Power converter 3 Auxiliary battery 4 DC / AC converter 5 Load 6 Bidirectional power converter 7 Lead battery 8 Shunt 9 Display part 10 Controller

Claims (6)

  A solar panel that converts solar energy into electrical energy, a power converter connected to the solar panel input, an auxiliary battery connected to the output of the power converter, and one terminal connected to the auxiliary battery Connected bi-directional power converter, lead battery connected to the other terminal of the bi-directional power converter, load connected to auxiliary battery, lead battery voltage, temperature, charge / discharge current, and It consists of a controller having means for measuring the voltage, temperature and charge / discharge current of the auxiliary battery, a power converter, a bidirectional power converter, a means for controlling the load, and a means for displaying their state. When the auxiliary battery is discharged, power is supplied to the load and the lead battery is charged. When the power is supplied to the load by electricity and the amount of photovoltaic power generation exceeds the power consumption by the load, the lead battery is preferentially charged and the lead battery terminal voltage reaches the preset upper limit voltage When the auxiliary battery is charged with surplus power and the amount of photovoltaic power generation falls below the total amount of power for charging the load and lead battery in the evening with the decay of sunlight, Power is supplied to the load and the lead battery is charged with the power of the auxiliary battery, the remaining capacity of the auxiliary battery is within a preset range, for a predetermined time, or until the charge current of the lead battery decays, When the lead battery continues to be charged, then the lead battery is discharged at a constant current for a certain period of time, and the power obtained by this discharge is supplied to the load. Charge the auxiliary battery, to discharge the case of lack of auxiliary battery, lead battery voltage CCV of the final stage of discharge. In addition, charging / discharging of the lead battery is prohibited for a predetermined period of time, power is supplied from the auxiliary battery to the load during that time, and the OCV immediately before canceling the charging / discharging prohibition is measured. A battery state detection device for a battery system for photovoltaic power generation that obtains the SOC of a lead battery from the relationship between CCV and CCV, and then obtains the SOC by integrating charge / discharge current until the SOC is obtained by the same method.   Even when the amount of sunshine is insufficient and charging of the lead battery does not reach the preset upper limit voltage, the same main battery is discharged and paused approximately 24 hours after the previous CCV and OCV measurement, and the CCV and OCV The battery state detection apparatus of the battery system for solar power generation according to claim 1 which performs measurement.   When the auxiliary battery is in a discharged state and the voltage per cell of the lead battery is 2.0 to 2.05 V or less, it is discharged for a certain time with a predetermined constant current, and is supplemented by surplus power during that time. Charging the battery and measuring the CCV at the end of discharging, further prohibiting charging / discharging of the lead battery by supplying power from the auxiliary battery to the load for a predetermined time, measuring the OCV immediately before the end of the prohibiting time, The battery state detection device for a battery system for solar power generation according to claim 1, wherein the SOC is obtained from a previously obtained relationship between OCV and SOC and a relationship between CCV and SOC.   When the SOC obtained from the OCV or the SOC obtained from the CCV is lower than the charge state expected from the end state of the charge, it is determined that sulfation has occurred, the display is displayed, and at the next sunshine The battery state detecting device for a battery system for solar power generation according to claim 1, wherein the charge of the lead battery in a state where the current is limited is extended.   The amount of fluctuation in unit time of the current charged and discharged via the bidirectional power converter is suppressed to be smaller than the amount of fluctuation in the amount of power generated by the solar cell panel per unit time, the amount of change in current consumed by the load The battery state detection device for a battery system for photovoltaic power generation according to claim 1, wherein the current for suppressing the fluctuation is supplied by an auxiliary battery.   The battery state detection device for a battery system for photovoltaic power generation according to claim 1, wherein the capacity of the auxiliary battery is in the range of 1/5 to 1/120 of the capacity of the lead battery.

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