JP2014171369A - Power supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply system capable of avoiding a charge stop state or a state where a discharge amount is remarkably reduced in supplying power stored in a plurality of batteries to a load apparatus.SOLUTION: A power supply system 1 comprises a system ECU 100 for acquiring a predetermined power storage information value on a power storage amount for each unit storage battery, and discharging a unit storage battery whose acquired power storage information value is the largest of those of storage battery devices 2. The system ECU 100 further calculates difference between the power storage information value acquired on the unit storage battery during the discharge and a storage power information value acquired on each unit storage battery not discharged. When the difference is equal to or smaller than a predetermined value with regard to a unit storage battery not discharged, the system ECU 100 makes the unit storage battery not discharged and the unit storage battery during the discharge be connected in parallel with the load apparatus 6 and discharges them in parallel.

Description

  The present invention relates to a power supply system capable of discharging stored power of a plurality of batteries to a load device that is a power load.

  As a conventional technique, a power supply system disclosed in Patent Document 1 is known. The power supply system includes a charging power source by natural energy power generation such as a solar cell, three batteries that can be charged with power from the charging power source, and a load circuit that can discharge the power of the battery. The power supply system employs a charge / discharge system that controls the connection order so that current does not flow between batteries when multiple batteries are connected in parallel, while charging the battery efficiently according to the power generated by the charging power supply. doing.

  According to this charge / discharge method, the voltage of each battery is measured, the charge switch is turned on to charge the battery with the lowest potential, and the discharge switch is turned on to discharge the battery with the highest potential. The connection order at this time is the charging power source, the lowest potential battery, the intermediate potential battery, the highest potential battery, and the load circuit. By connecting in this order from the battery with the lowest potential, parallel connection is performed so that no current flows from the battery with the intermediate potential to the battery with the lowest potential.

  During discharge, the battery is switched in order of voltage in a cycle proportional to the discharge voltage, the discharge switch for the battery with the highest potential is turned on, the charge switch for the battery with the lowest potential is turned on, and Connect the switches in the order that current does not flow in. However, when the power generation voltage of the charging power supply is higher than the voltage of the battery with the highest potential, control is performed so that the discharge current does not flow from each battery to the load circuit.

JP 2011-61990 A

  In the system described in Patent Document 1, one of the three batteries having the highest potential is discharged to the load circuit, and the remaining batteries are charged. In the case of a system that discharges only from one battery as in Patent Document 1, when the discharge of the battery is switched to the discharge from the other battery, the power supply to the load circuit is performed. There arises a problem that it is temporarily interrupted or the power supply amount is greatly reduced.

  Therefore, the present invention has been made in view of the above problems, and its purpose is to significantly reduce the discharge stop state and the discharge amount when supplying power stored in a plurality of batteries to a load device. An object of the present invention is to provide a power supply system that can avoid the situation.

In order to achieve the above object, an invention relating to a power supply system includes a storage battery device (2) configured to have a plurality of unit storage batteries (20, 21, 22) for discharging power to a load device (6). And a control device (100) for controlling discharge of each unit storage battery with respect to the load device,
The control device
For each unit storage battery, a predetermined storage information value related to the storage amount is obtained, and among the storage battery devices, discharging is performed for the unit storage battery having the largest stored storage information value,
Furthermore, if there is a non-discharged unit storage battery in which the difference between the storage information value acquired for the unit storage battery being discharged and the storage information value acquired for each unit storage battery that is not discharged is equal to or less than a predetermined value, A discharge unit storage battery and a discharging unit storage battery are connected in parallel to a load device to perform parallel discharge.

  According to the present invention, when discharge to a load device is required, a unit storage battery having the largest predetermined storage information value is detected, and discharge is started from this unit storage battery. The difference between the storage information value acquired for the unit storage battery that has already been discharged and the storage information value acquired for each unit storage battery that has not yet been discharged is calculated. In this case, the corresponding unit storage battery is determined as the unit storage battery to be discharged next. The unit storage battery determined in this way is connected in parallel to the load device together with the unit storage battery currently being discharged, and discharged in parallel. In other words, since the unit storage battery that is already discharged has a reduced storage amount due to continued discharge, a unit storage battery that has no difference in storage amount compared to a unit storage battery that is being discharged is selected from among non-discharge unit storage batteries. A plurality of unit storage batteries can be discharged simultaneously by sequentially connecting in parallel.

  In this way, the electric power stored in the storage battery device including a plurality of unit storage batteries composed of one or a plurality of single cells is discharged from the unit storage battery having a large storage amount to the load device and sequentially discharged in parallel. The power of all unit storage batteries can be discharged without interruption. Therefore, according to the present invention, when supplying the electric power stored in the plurality of storage batteries to the load device, it is possible to obtain an electric power supply system that can avoid a stop state of discharge and a state in which the discharge amount is significantly reduced.

  In addition, the code | symbol in the parenthesis attached | subjected to each said means is an example which shows a corresponding relationship with the specific means of embodiment description later mentioned.

It is a block diagram which shows the structure of one Embodiment of the electric power supply system to which this invention is applied. It is a flowchart which shows the process regarding the discharge control of an electric power supply system. It is a figure for demonstrating the discharge control of an electric power supply system.

(First embodiment)
Below, the electric power supply system 1 which is one Embodiment to which this invention is applied is demonstrated. As shown in FIG. 1, the power supply system 1 includes a storage battery device 2, a solar power generation device, a load device 6 that operates using power obtained from the power generated by the solar power generation device, and a load device. 6 and a system ECU 100 that controls the amount of generated power to be discharged. Further, the load device 6 can be operated using electric power obtained from the electric power system 5.

  The load device 6 includes at least one electric device that is operated using electric power. As electrical equipment, tablet equipment, cordless portable terminals such as mobile phones, lighting equipment used in buildings such as houses, hot water supply equipment, air conditioning equipment, floor heating equipment, and other electrical appliances can be employed. The load device 6 may be a stationary storage battery installed in a building or land, a storage battery mounted on a vehicle (plug-in hybrid vehicle, electric vehicle, etc.), or the like.

  The storage battery device 2 energizes the three unit storage batteries 20, 21, 22, the battery monitoring ECUs 200, 210, 220 for monitoring the state of each predetermined unit storage battery, and the predetermined unit storage battery and the power conditioner 3, respectively. And relays 201, 211, and 221 that are turned on and off. Each of the unit storage batteries 20, 21, and 22 is composed of a single unit cell, or a unit cell assembly in which a plurality of unit cells are connected to be energized. The unit cell assembly is a battery unit that can be charged and discharged by combining a plurality of unit cells such as a nickel-hydrogen secondary battery, a lithium ion secondary battery, and an organic radical battery. Each unit storage battery 20, 21, 22 constitutes a unit that supplies power to the power conditioner 3 in one unit. Moreover, a stationary storage battery and a vehicle-mounted storage battery can be adopted for each of the unit storage batteries 20 to 22.

  The battery monitoring ECU 200 is a battery monitoring unit that monitors the state of the unit storage battery 20 (for example, voltage between terminals, current, storage rate (hereinafter also referred to as SOC (State Of Charge)), temperature, internal resistance, etc.). . The battery monitoring ECU 200 receives detection results from various sensors that detect the inter-terminal voltage, current, and temperature for the unit storage battery 20. The battery monitoring ECU 210 is a battery monitoring unit that monitors the state of the unit storage battery 21 (for example, voltage between terminals, current, SOC, temperature, internal resistance, etc.). The battery monitoring ECU 210 receives detection results from various sensors that detect the inter-terminal voltage, current, and temperature for the unit storage battery 21. The battery monitoring ECU 220 is a battery monitoring unit that monitors the state of the unit storage battery 22 (for example, voltage between terminals, current, SOC, temperature, internal resistance, etc.). The battery monitoring ECU 220 receives detection results from various sensors that detect the inter-terminal voltage, current, and temperature for the unit storage battery 22.

  The inter-terminal voltage is a voltage value measured according to the amount of electricity stored in each unit storage battery, and is measured as a value according to the characteristics specific to each unit storage battery during discharging and during charging. Therefore, the measured inter-terminal voltage is closely related to the storage rate of each unit storage battery. The current is closely related to the voltage drop value of the inter-terminal voltage generated for the discharging unit storage battery. Therefore, for each of the unit storage batteries 20, 21, 22, the voltage drop value during discharge becomes a value corresponding to the load current.

  Each of battery monitoring ECUs 200, 210, and 220 is configured to be able to communicate with system ECU 100. The system ECU 100 acquires at least the inter-terminal voltage, current, and SOC for each unit storage battery from each of the battery monitoring ECUs 200, 210, and 220.

  The relay 201 is controlled by the system ECU 100 and is turned on and off so as to open and close the electrical connection between the unit storage battery 20 and the power conditioner 3, thereby supplying and interrupting power to the load device 6. . The relay 211 is controlled by the system ECU 100 and is turned on and off so as to open and close the electrical connection between the unit storage battery 21 and the power conditioner 3, thereby supplying and interrupting power to the load device 6. . The relay 221 is controlled by the system ECU 100 and is turned on and off so as to open and close the electrical connection between the unit storage battery 22 and the power conditioner 3, thereby supplying and cutting off power to the load device 6. .

  The solar power generation device includes a solar cell panel 4 including a solar cell that generates solar energy by generating solar energy, and a solar power conditioner (not shown). The solar cell panel 4 is provided with a temperature sensor that detects the temperature of the solar cell panel 4. The system ECU 100 can detect the surface temperature of the solar cell that has received solar radiation by acquiring the detection signal of the temperature sensor. The DC power generated by the solar battery panel 4 from the solar energy is sent to a solar power conditioner. The power conditioner for sunlight is a power conversion device that efficiently converts DC power generated by the solar battery panel 4 into AC power.

  The power conditioner 3 is a power conversion device that efficiently converts the stored power of the unit storage batteries 20, 21 and 22 connected to be energized when the relays 201, 211, and 221 are turned on from DC power to AC power. is there. The operation of the power conditioner 3 is controlled by the system ECU 100. The power from the unit storage batteries 20, 21, and 22 sent to the power conditioner 3 is converted between AC and DC, and is sent to a distribution board (not shown) via a breaker, for example. The distribution board is connected to the load device 6, the solar battery panel 4, and the power system 5 by a single-phase three-wire AC power line. Therefore, the grid power supplied from the power grid 5 of the power company, the generated power of the solar cell panel 4, and the stored power sent to the power conditioner 3 are the electrical equipment that constitutes the load equipment 6 through the distribution board, etc. To be supplied.

  The power supply system 1 also includes a current detection device (not shown) that detects the operating current of the solar power generation device and a voltage detection device (not shown) that detects the operating voltage of the solar power generation device. Yes. The system ECU 100 can detect the operating current, the operating voltage, and the amount of supplied power of the photovoltaic power generation device by acquiring the detection signals of the current detecting device and the voltage detecting device. Further, the system ECU 100 may detect the amount of power supplied from the power system 5 and the reverse power flow (power sales power amount) to the power system 5 by detecting the power flowing through the power system 5 using these detection devices. it can.

  The system ECU 100 is a control device that controls at least charging to the storage battery device 2 and discharging from the storage battery device 2 to the load device 6. When the system ECU 100 obtains a signal for requesting charging of the storage battery device 2, the system ECU 100 controls the operation of the power conditioner 3 and the relays 201 to 221 to generate power from the photovoltaic power generator in the electrically connected unit storage battery. Electric power or electric power from the electric power system 5 is charged. For example, the system ECU 100 charges the storage battery device 2 with power from the power system 5 when the generated power of the solar power generation device cannot be obtained.

  The system ECU 100 can control the load device 6 to select and discharge any of the stored power of the storage battery device 2, the power generated by the solar power generation device, and the power supplied from the power system 5. When the system ECU 100 discharges the stored power of the storage battery device 2 to the load device 6, the system ECU 100 acquires a predetermined storage information value related to the storage amount for each unit storage battery. The predetermined storage information value to be acquired is a voltage between terminals in each unit storage battery. Furthermore, when determining the unit storage battery to be discharged first, the system ECU 100 acquires both the terminal voltage in each unit storage battery and the SOC of each unit storage battery.

  When the system ECU 100 acquires a signal requesting power supply to the load device 6, the system ECU 100 controls the operation of the power conditioner 3 and the relays 201 to 221 to discharge the stored power of the electrically connected unit storage batteries. The electronic load device 6 is supplied. For example, the system ECU 100 follows the flowchart shown in FIG. 2 described later so that the discharge stop state does not occur when the generated power of the photovoltaic power generation apparatus or the power from the power system 5 cannot be obtained (for example, during a power failure). The stored power of the storage battery device 2 can be discharged and self-sustained discharge can be performed.

  System ECU 100 incorporates a storage device such as a RAM. The system ECU 100 stores, for each of the unit storage batteries 20, 21, 22, characteristic data relating to the voltage drop value of the inter-terminal voltage according to the load current and characteristic data relating to the relationship between the SOC and the voltage drop value of the inter-terminal voltage. Pre-stored in the device. The system ECU 100 uses the characteristic data stored in advance for control when discharging the stored power of the storage battery device 2 to the load device 6. The characteristic data is used when the process of step 100 in the flowchart shown in FIG. Further, the characteristic data is learned and accumulated during execution of the flowchart shown in FIG.

  Further, the system ECU 100 measures the inter-terminal voltage and the SOC of the unit storage battery at a timing when the unit storage battery is not discharged. The measured value for the unit storage battery that is not being discharged is stored and used to calculate the voltage drop for the unit storage battery that is being discharged. In addition, this measured value is used when performing the processing of step 100 from the next time on, so that the inter-terminal voltage measured for the unit storage battery being discharged is a correction value that takes into account the voltage drop value that is updated as needed. Will be corrected.

  Next, characteristic processing executed by the system ECU 100 when discharging from the storage battery device 2 to the load device 6 will be described with reference to FIGS. 2 and 3. The process according to the operation example is mainly executed by the system ECU 100.

  The system ECU 100 receives a discharge request from the storage battery device 2 to the load device 6 or a discharge request from the load device 6, and obtains the generated power of the solar power generation device and the power from the power system 5. If not, control according to the flowchart of FIG. 2 is started. The flowchart in FIG. 2 ends when there is no discharge request from the storage battery device 2 to the load device 6.

  First, in step 10, for each unit storage battery, an open circuit voltage with respect to the SOC is acquired and stored in a storage device. Further, in step 2, the SOC of each unit storage battery is acquired. With these processes, the battery monitoring ECUs 200 to 220 measure the inter-terminal voltage and the SOC at a timing when the battery is not discharged, and the system ECU 100 acquires the voltage value when no current flows out for each unit storage battery. Can do.

  The voltage value relating to the unit storage battery when not discharged, which is measured in step 10, is stored and contributes to the update of the characteristic data for obtaining the voltage drop, and the voltage drop is taken into account in later step 100. It is used when calculating the correction value.

  Next, in Step 30, it is determined whether or not there are one or more unit storage batteries with SOC exceeding 0% for the SOCs of all the unit storage batteries acquired in Step 20. That is, it is determined whether there is a unit storage battery in which the amount of stored electricity remains.

  If it is determined in step 30 that there is no unit storage battery with an SOC exceeding 0%, that is, the storage amount of all the unit storage batteries is zero, the discharge from the storage battery device 2 to the load device 6 cannot be performed immediately. Returning to step 10, each subsequent process is continued.

  On the other hand, if it is determined in step 30 that there is one or more unit storage batteries having an SOC exceeding 0%, system ECU 100 controls in step 40 to turn on the corresponding relay for the unit storage battery having the maximum SOC. . Thereby, the unit storage battery which is the maximum SOC and the power conditioner 3 are electrically connected. In step 50, the stored power of the unit storage battery is supplied to the power conditioner 3, converted from DC power to AC power, and then discharged to the load device 6.

  Next, at step 60, the voltage value between terminals, the SOC, and the current value are measured for all unit storage batteries. That is, the system ECU 100 acquires the inter-terminal voltage value, the SOC, and the current value for each unit storage battery for both the discharging unit storage battery and the non-discharged unit storage battery.

  In step 70, it is determined whether or not the SOC of the unit storage battery being discharged is higher than 0%. If NO is determined in step 70, the discharge cannot be continued. Therefore, in step 75, the system ECU 100 turns off the relay in the on state to release the electrical connection between the unit storage battery being discharged and the power conditioner 3. Then, the process for terminating the discharge is executed, and this flowchart is terminated.

  If YES is determined in step 70, it is determined in step 80 whether or not there is a non-discharged unit storage battery that is not discharged. If parallel discharge has already been performed for all the unit storage batteries, NO is determined in step 80, and the current discharge is continued by returning to step 50. If there is a unit storage battery that has not yet started discharging, YES is determined in step 80, and further, in step 90, it is determined whether there is a non-discharged unit storage battery with an SOC exceeding 0%.

  If NO is determined in step 90, the process returns to step 50 and the current discharge is continued. If there is a unit storage battery waiting for the start of discharge, the determination in step 90 is YES, and the process of step 100 is executed in order to determine the unit storage battery to start discharging next.

  In step 100, processing for determining the next unit storage battery to be discharged in parallel is performed by the following method. The system ECU 100 acquires the inter-terminal voltage for the unit storage battery currently being discharged. When there are a plurality of unit storage batteries that are being discharged, the respective inter-terminal voltages are acquired, and the average value of these is calculated, or any inter-terminal voltage is employed. Moreover, system ECU100 acquires the voltage between terminals about each of a non-discharge unit storage battery.

  System ECU 100 corrects the inter-terminal voltage acquired for the unit storage battery being discharged. In this correction process, the voltage drop value during discharge is obtained using the above characteristic data stored in the storage device, and the correction value is obtained by adding the voltage drop value during discharge to the acquired inter-terminal voltage.

  When the characteristic data stored in the storage device is characteristic data related to the voltage drop value of the inter-terminal voltage according to the load current, the system ECU 100 acquires the current value of the unit storage battery that is currently being discharged. System ECU 100 obtains the voltage drop value of the unit storage battery during discharge from the acquired current value (load current) and characteristic data. Further, when the characteristic data stored in the storage device is characteristic data related to the relationship between the SOC and the voltage drop value of the inter-terminal voltage, the system ECU 100 acquires the SOC of the unit storage battery currently being discharged. System ECU 100 obtains a voltage drop value of the unit storage battery during discharge from the acquired SOC and characteristic data.

  The correction value is calculated by adding the voltage drop value thus obtained to the acquired inter-terminal voltage. Thereby, the voltage between terminals which excluded the influence of the voltage drop is calculated | required, and the precision can be improved about the comparison result of the voltage between terminals regarding the unit storage battery in discharge and a non-discharge unit storage battery.

  As described above, in step 100, whether or not the value obtained by subtracting the inter-terminal voltage of the non-discharged unit storage battery from the correction value of the inter-terminal voltage for the discharging unit storage battery is equal to or less than a predetermined value. Determine whether. In this case, determination is performed for all unit storage batteries that are not discharged. The predetermined value is zero or a predetermined value other than zero.

  If NO is determined in step 100, that is, if it is determined that there is no non-discharged unit storage battery that is equal to or less than a predetermined value, the SOC of the unit storage battery that is being discharged is still sufficiently higher than the SOC of other discharge-ready unit storage batteries. Therefore, the process returns to step 50 to continue the current discharge.

  If it is determined as YES in step 100, that is, if it is determined that there is a non-discharged unit storage battery that is equal to or less than a predetermined value, the system ECU 100 controls to turn on the relay corresponding to the corresponding unit storage battery in step 110. As a result, the unit storage battery previously discharged and the unit storage battery newly determined in step 100 are connected in parallel to the load device 6. And it returns to step 50 and performs the parallel discharge which added the unit storage battery which discharges newly.

  Thus, if parallel discharge by two or more unit storage batteries is implemented, it will return to step 50 and will continue discharge. Further, if it is determined in step 70 that the SOC of the unit storage batteries during parallel discharge is greater than 0%, it is determined again in step 100 whether there are any remaining non-discharge unit storage batteries that satisfy the discharge condition. If it is determined in step 100 that there is a unit storage battery that satisfies the discharge condition, in step 110 and step 50, parallel discharge with the corresponding unit storage battery added is performed.

  By repeatedly executing the processing from step 50 to step 110 as described above, parallel discharge can be performed for all unit storage batteries whose SOC is not 0%. That is, for all unit storage batteries having a storage amount, the power stored in the storage battery device 2 can be used for the discharge to the load device 6 by adding to the parallel discharge in descending order of the storage amount. is there. Eventually, in the process of repeatedly executing the processing from step 50 to step 110, all unit storage batteries having a charged amount are discharged in parallel, and if it is determined in step 70 that the SOC has become zero, discharging is performed in step 75. Execute the process to end.

  Next, the discharge control of the storage battery device 2 described according to the flowchart of FIG. 2 will be described with reference to FIG. 3 from the viewpoint of the change in the SOC of the unit storage battery. For example, as shown in FIG. 3, the storage battery device 2 has three unit storage batteries, and the SOC at the time when the discharge request is made is assumed to be larger in the order of the unit storage battery A, the unit storage battery B, and the unit storage battery C. .

  In this case, discharge is started about the unit storage battery A with the largest SOC in Step 40 and Step 50 of FIG. When the discharge from only the unit storage battery A proceeds, the SOC of the unit storage battery A decreases, and becomes the same level as the SOC of the unit storage battery B having the second largest SOC. At this time, in step 100, step 110, and step 50 of FIG. 2, the unit storage battery B is connected to the load device 6 in parallel with the unit storage battery A, and the first parallel discharge by the unit storage battery A and the unit storage battery B is started. Is done.

  Further, when parallel discharge by the unit storage battery A and the unit storage battery B proceeds, the SOC of the unit storage battery A and the unit storage battery B decreases, and becomes the same level as the SOC of the unit storage battery C having the third largest SOC. At this time, the unit storage battery C is connected in parallel to the unit storage battery A and the unit storage battery B with respect to the load device 6 in Step 100, Step 110, and Step 50 of FIG. 2, and the unit storage battery A, the unit storage battery B, and the unit storage battery C are connected. The second parallel discharge due to is started.

  And if 2nd parallel discharge progresses, the SOC of the unit storage battery A, the unit storage battery B, and the unit storage battery C will decrease, and the SOC of all the unit storage batteries will become zero. At this time, the discharge to the load device 6 is completed in Step 70 and Step 75 of FIG.

(effect)
Below, the effect which the electric power supply system 1 of 1st Embodiment brings is described. The power supply system 1 includes a storage battery device 2 configured to have a plurality of unit storage batteries 20, 21, and 22 that discharge power to the load device 6, and control for controlling discharge of each unit storage battery with respect to the load device 6. An apparatus (system ECU 100).

  The system ECU 100 acquires a predetermined storage information value related to the storage amount for each unit storage battery, and discharges the unit storage battery having the largest acquired storage information value among the storage battery devices 2. Further, system ECU 100 calculates the difference between the storage information value acquired for the unit storage battery being discharged and the storage information value acquired for each unit storage battery that is not discharged. When there is a non-discharge unit storage battery in which this difference is equal to or less than a predetermined value, the system ECU 100 performs parallel discharge by connecting the corresponding non-discharge unit storage battery and the discharging unit storage battery in parallel to the load device 6. The power storage information value is predetermined information related to the power storage amount set for each unit storage battery. For example, the detected value of the inter-terminal voltage in each unit storage battery 20-22, the SOC (power storage rate) of each unit storage battery 20-22, etc. It is.

  According to this control, when discharge to the load device 6 is required, the unit storage battery having the largest predetermined storage information value is detected, and discharge is started from this unit storage battery. The difference between the storage information value acquired for the unit storage battery that has already been discharged and the storage information value acquired for each unit storage battery that has not yet been discharged is calculated. In this case, the corresponding unit storage battery is determined as the unit storage battery to be discharged next.

  The unit storage battery determined in this way is connected in parallel to the load device 6 together with the unit storage battery currently being discharged, and discharged in parallel. That is, the unit storage battery that has already been discharged has a lower storage amount due to continued discharge, so the unit of the remaining storage unit battery has no difference in the storage amount compared to the unit storage battery that is being discharged. A plurality of unit storage batteries can be discharged simultaneously by sequentially connecting storage batteries in parallel. In other words, the unit storage battery that has started discharging first has its stored amount approaching the stored amount of other unit storage batteries, and continues to discharge together with the unit storage battery having the next largest stored amount. At this time, the two discharged unit storage batteries have the same level of charge, and when the charge of each unit battery being discharged drops to the level of the charge of the unit battery having the next highest charge, 3 Two unit storage batteries are connected in parallel and discharged simultaneously. By continuing such discharge, it is possible to cause the load device 6 to discharge without leaving the power stored in all the unit storage batteries and without further stopping the discharge.

  Therefore, according to the power supply system 1, when the power stored in the plurality of unit storage batteries is supplied to the load device 6, it is possible to avoid a stop state of discharge or a state in which the discharge amount is significantly reduced. Therefore, the power supply system 1 can avoid a state where power supply to the load device 6 is stopped, and can stably discharge the stored power of the storage battery device 2.

  Further, when determining the unit storage battery to be discharged first, the system ECU 100 acquires both the terminal voltage in each unit storage battery and the SOC (storage rate) of each unit storage battery as the predetermined storage information value. According to this, by using both the inter-terminal voltage and the SOC in each unit storage battery, the unit storage battery to be discharged first can be accurately determined as compared with the case where only the inter-terminal voltage is used.

  This is particularly useful when the discharge characteristics regarding the terminal voltage and SOC of the unit storage battery are as follows. Usually, in the discharge characteristics of a battery, the voltage between terminals (voltage value) decreases as the SOC decreases. On the other hand, for example, there is a battery having a discharge characteristic in which the voltage between terminals does not decrease uniformly as the SOC decreases, but decreases stepwise. In other words, the discharge characteristics have a high change region where the inter-terminal voltage greatly changes and a low change region where the change does not change much with respect to the change in SOC.

  When a battery having such discharge characteristics is employed, an accurate storage amount can be obtained for each unit storage battery by acquiring both the SOC and the inter-terminal voltage as the predetermined storage information value as described above. . Accordingly, it is possible to avoid the situation where the unit storage battery to be discharged first is mistaken and the discharge is finally terminated with the remaining power stored in the storage battery device 2, and it is possible to contribute to the implementation of efficient discharge control. is there. As described above, by obtaining both the SOC and the inter-terminal voltage as the predetermined power storage information value, it is possible to provide discharge control suitable for the discharge characteristics unique to each unit storage battery.

  Further, when determining a non-discharge unit storage battery that is connected in parallel with a unit storage battery that is being discharged, the system ECU 100 acquires the SOC (storage rate) of each unit storage battery as a predetermined storage information value. According to this, by adopting the SOC as the predetermined power storage information value, it is possible to improve the detection accuracy of the non-discharge unit storage batteries to be connected in parallel next. In addition, since the detection accuracy is high, it is possible to detect non-discharged unit storage batteries that are closer in storage capacity than the unit storage batteries that are being discharged, so that current flows between these unit storage batteries connected in parallel. Can be suppressed.

  The system ECU 100 acquires at least a terminal voltage in the unit storage battery as a predetermined power storage information value. The system ECU 100 stores in advance characteristic data regarding the voltage drop value of the voltage between terminals for each unit storage battery. The system ECU 100 corrects the inter-terminal voltage acquired for the unit storage battery being discharged to a value excluding the voltage drop using the stored voltage drop value, and the corrected inter-terminal voltage value and the non-discharged voltage. The difference with the terminal voltage acquired about each unit storage battery is calculated.

  Normally, the voltage between the terminals of a battery does not drop when it is not discharged, but during discharge, a voltage drop occurs according to the load current, and the detected voltage value is lower than that of a non-discharged battery. Lower. Therefore, characteristic data relating to the voltage drop value of the inter-terminal voltage is stored in advance for each unit storage battery, and the terminal voltage during discharge is corrected to a value excluding the voltage drop using this characteristic data. By using the corrected voltage value to calculate the difference between the terminals of each non-discharged unit storage battery, a comparison that does not include the influence of the voltage drop during discharge can be performed.

  Further, the system ECU 100 stores in advance characteristic data regarding the relationship between the SOC (power storage rate) and the voltage drop value of the inter-terminal voltage for each unit storage battery. The system ECU 100 measures the inter-terminal voltage and the SOC (power storage rate) in the unit storage battery at a timing when the unit storage battery is not discharged, stores these measurement values, and stores the stored measurement values and the stored characteristic data. Are used to determine the voltage drop.

  According to this, the stored measurement value is used when the process of step 100 from the next time is performed. Thus, the voltage between terminals measured about the unit storage battery in discharge can be correct | amended to the correction value which considered the voltage drop value updated by the measured value in the timing which is not discharged. Therefore, according to this control, it is possible to provide a control adapted to the discharge characteristics of the unit storage battery that can change depending on the use as needed.

(Other embodiments)
The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  The structure of the said embodiment is an illustration to the last, Comprising: The scope of the present invention is not limited to the range of these description. The scope of the present invention is indicated by the description of the scope of claims, and further includes meanings equivalent to the description of the scope of claims and all modifications within the scope.

  The power supply system according to the present invention is not limited to a supply source for supplying power to the load device 6 including all of the solar power generation device, the storage battery device 2, and the power system 5 as in the above embodiment. For example, the power supply system 1 may use the storage battery device 2 and the power system 5 as a power supply source, or may use the storage battery device 2 and the solar power generation device as a power supply source.

  The storage battery device included in the power supply system according to the present invention only needs to include a plurality of unit storage batteries. Therefore, it is not limited to the form provided with the three unit storage batteries 20, 21, and 22 like the storage battery apparatus 2 of the said embodiment. For example, the storage battery device 2 may include two or four or more unit storage batteries.

  In the said embodiment, although the building where the load apparatus 6 is installed was a house, for example, it is not limited to this form. For example, the building may be a commercial facility, a public facility, a factory, a warehouse, or the like.

  In the above embodiment, it is determined in step 70 of the flowchart of FIG. 2 whether or not the SOC of the unit battery being discharged is greater than 0%, but it is determined whether or not the SOC is greater than a predetermined value. It may be replaced. That is, by setting the predetermined value to a value larger than 0%, it is possible to prevent the entire amount of power stored in the unit storage battery from being discharged. This replacement with a predetermined value greater than 0% can be applied to step 90 as well.

2 ... Storage battery device 6 ... Load device 20, 21, 22 ... Unit storage battery 100 ... System ECU (control device)

Claims (5)

A storage battery device (2) comprising a plurality of unit storage batteries (20, 21, 22) for discharging electric power to the load device (6);
A control device (100) for controlling the discharge of each unit storage battery to the load device;
With
The controller is
For each unit storage battery, a predetermined storage information value related to the storage amount is acquired, and among the storage battery devices, the unit storage battery having the largest acquired storage information value is discharged,
Further, when there is a non-discharged unit storage battery in which the difference between the storage information value acquired for the unit storage battery being discharged and the storage information value acquired for each unit storage battery that is not discharged is a predetermined value or less, A power supply system, wherein the corresponding non-discharged unit storage battery and the discharging unit storage battery are connected in parallel to the load device for parallel discharge.   When determining the unit storage battery to be discharged first, the control device acquires both the terminal voltage in each unit storage battery and the storage rate of each unit storage battery as the predetermined storage information value. The power supply system according to claim 1, wherein:   The control device acquires a storage rate of each unit storage battery as the predetermined storage information value when determining the non-discharge unit storage battery connected in parallel to the discharging unit storage battery. The power supply system according to claim 1 or 2. As the predetermined power storage information value, at least the terminal voltage in the unit storage battery is acquired,
The control device stores in advance characteristic data relating to the voltage drop value of the voltage between terminals for each unit storage battery,
The control device corrects the inter-terminal voltage obtained for the unit battery being discharged using the characteristic data relating to the stored voltage drop value to a value excluding the voltage drop, and after the correction The difference between the inter-terminal voltage value and the inter-terminal voltage acquired for each non-discharged unit storage battery is calculated, and when there is the non-discharged unit storage battery in which the calculated difference is less than or equal to the predetermined value, the corresponding non- The power supply according to any one of claims 1 to 3, wherein the unit storage battery for discharging and the unit storage battery for discharging are connected in parallel to the load device to perform parallel discharge. system. The control device stores in advance characteristic data regarding the relationship between the storage rate and the voltage drop value of the voltage between the terminals for each unit storage battery,
The control device measures an inter-terminal voltage and a storage rate in the unit storage battery at a timing when the unit storage battery is not discharged, stores these measurement values, and uses the stored measurement values and the characteristic data. The power supply system according to claim 4, wherein the voltage drop is obtained.

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