Patent Description:
In recent years, the use of safe and clean natural energy including solar power generation and wind power generation has been growing. However, the output of natural energy is unstable, so that a large scale of introduction of natural energy may adversely affect the voltage or frequency of the power grid. If the supply of natural energy greatly exceeds power demand, natural-energy power generation systems need to be stopped, lowering the use rate of power generation facilities.

Conventionally, to stabilize the voltage and frequency of the power grid, a governor-free control and a load frequency control (LFC) function of generators, and load leveling by pumped-storage power generation have been implemented. However, issues arise such as an insufficient lower margin of generators, restrictions on construction site of a pumped storage power plant, and a long construction period.

In view of this, stationary large-scale storage battery systems including secondary batteries and relatively less restricted by the conditions of site are increasingly attracting attention.

Such a large-scale storage battery system is known, including a battery pack which incorporates secondary battery blocks in which parallel cell blocks of parallelconnected battery cells are connected in series.

In <CIT> a battery monitoring device is disclosed comprising a voltage detector for detecting voltage of each of parallel cell blocks, and a current detector for detecting carried current of a secondary battery block.

In <CIT> discloses a diagnostic apparatus for determining a battery charge status of a battery set.

The invention is defined by the battery monitoring devices according to claims <NUM> or <NUM> and the corresponding methods according to claims <NUM> or <NUM>.

<FIG> is a schematic configuration diagram of a natural-energy power generation system including a storage battery system according to an embodiment.

A natural-energy power generation system <NUM> functions as a power system and includes a natural-energy power generation unit <NUM>, a power meter <NUM>, a storage battery system <NUM>, a transformer <NUM>, a storage battery controller <NUM>, and a host control device <NUM>. The natural-energy power generation unit <NUM> can output system power, using natural energy such as solar light, hydraulic-power, wind power, biomass, and geothermal energy (renewable power). The power meter <NUM> measures the power generated by the natural-energy power generation unit <NUM>. The storage battery system <NUM> is charged with surplus electric power of the natural-energy power generation unit <NUM> on the basis of the measurement result of the power meter <NUM>, and discharges power to make up for underpower and superimposes the power on the power generated by the natural-energy power generation unit <NUM> for output. The transformer <NUM> converts the voltage of the output power from the natural-energy power generation unit <NUM> (including power on which the output power from the storage battery system <NUM> is superimposed). The storage battery controller <NUM> locally controls the storage battery system <NUM>. The host control device <NUM> remotely controls the storage battery controller <NUM>.

<FIG> is a schematic configuration block diagram of the storage battery system according to the embodiment. The storage battery system <NUM> includes a storage battery device <NUM> that stores therein electric power, and a power conditioning system (PCS) <NUM> that converts direct-current power supplied from the storage battery device <NUM> into alternating-current power having a desired power quality and supplies the alternating-current power to a load.

The storage battery device <NUM> includes a plurality of battery board units <NUM>-<NUM> to <NUM>-N (N being a natural number), and a battery terminal board <NUM> connected to the battery board units <NUM>-<NUM> to <NUM>-N.

The battery board units <NUM>-<NUM> to <NUM>-N include a plurality of battery boards <NUM>-<NUM> to <NUM>-M (M being a natural number) that are connected to each other in parallel, a gateway device <NUM>, and a direct-current power supply device <NUM> that supplies direct-current power to a battery management unit (BMU) and cell monitoring units (CMUs) for operation, which will be described below.

A configuration of the battery boards will now be described.

Each of the battery boards <NUM>-<NUM> to <NUM>-M is connected to output power supply lines (buses) LHO and LLO via a high-potential power supply line LH and a low-potential power supply line LL, and supplies electric power to the PCS <NUM> being a main circuit.

The battery boards <NUM>-<NUM> to <NUM>-M have the same configuration, therefore, the battery board <NUM>-<NUM> is explained as an example.

The battery board <NUM>-<NUM> includes a plurality (<NUM> in <FIG>) of secondary battery packs <NUM>-<NUM> to <NUM>-<NUM>, a service disconnect <NUM> provided between the secondary battery pack <NUM>-<NUM> and the secondary battery pack <NUM>-<NUM>, a current sensor <NUM>, and a contactor <NUM>. The secondary battery packs <NUM>-<NUM> to <NUM>-<NUM>, the service disconnect <NUM>, the current sensor <NUM>, and the contactor <NUM> are connected in series.

In the configuration described above, the secondary battery packs <NUM>-<NUM> to <NUM>-<NUM> each include a storage battery module and a CMU. The whole secondary battery packs <NUM>-<NUM> to <NUM>-<NUM> include a plurality of storage battery modules <NUM>-<NUM> to <NUM>-<NUM>, and a plurality (<NUM> in <FIG>) of CMUs <NUM>-<NUM> to <NUM>-<NUM> included in the storage battery modules <NUM>-<NUM> to <NUM>-<NUM>, respectively.

The storage battery modules <NUM>-<NUM> to <NUM>-<NUM> form a battery pack in which battery cells are connected in series and in parallel. The storage battery modules <NUM>-<NUM> to <NUM>-<NUM> connected in series form a battery pack group.

The battery board <NUM>-<NUM> also includes a BMU <NUM> connected to the communication line of each of the CMUs <NUM>-<NUM> to <NUM>-<NUM> and the output line of the current sensor <NUM>.

Under the control of the gateway device <NUM>, the BMU <NUM> controls the entire battery board <NUM>-<NUM>, and opens and closes the contactor <NUM> on the basis of a result of the communication (voltage data and temperature data, which will be described below) with each of the CMUs <NUM>-<NUM> to <NUM>-<NUM> and a result of the detection of the current sensor <NUM>.

Next, a configuration of the battery terminal board <NUM> will be described.

The battery terminal board <NUM> includes a plurality of board breakers <NUM>-<NUM> to <NUM>-N corresponding to the battery board units <NUM>-<NUM> to <NUM>-N, and a master device <NUM> being a microcomputer for controlling the entire storage battery device <NUM>.

The master device <NUM> and the PCS <NUM> are connected via a control power supply line <NUM> through which power is supplied to the master device <NUM> via an uninterruptible power system (UPS) 12A of the PCS <NUM> and a control communication line <NUM> being Ethernet (registered trademark) for transfer of control data.

A detailed configuration of the secondary battery packs <NUM>-<NUM> to <NUM>-<NUM> will now be described.

<FIG> is a diagram for explaining a detailed configuration of a secondary battery pack.

The secondary battery packs <NUM>-<NUM> to <NUM>-<NUM> have the same configuration, therefore, the secondary battery pack <NUM>-<NUM> is explained as an example below.

The storage battery module <NUM>-<NUM> of the secondary battery pack <NUM>-<NUM> includes a plurality (three in <FIG>) of parallel cell blocks <NUM> that are connected in series, and each of the parallel cell blocks <NUM> includes a plurality (two in <FIG>) of battery cells <NUM> that are connected to each other in parallel.

The CMU <NUM>-<NUM> of the secondary battery pack <NUM>-<NUM> includes a voltage detector <NUM>, a current detector <NUM>, a set-value storage <NUM>, a calculator <NUM>, and a current control <NUM>. The voltage detector <NUM> detects voltage of each of the parallel cell blocks <NUM>. The current detector <NUM> detects conduction current of the storage battery module <NUM>-<NUM> with a shunt resistor or a hall current transformer (CT), for example. The set-value storage <NUM> stores in advance various types of set-value data such as set-value data for anomaly determination (reference direct-current internal resistance ratio) on the storage battery module <NUM>-<NUM>. The calculator <NUM> receives output signals from the voltage detector <NUM> and the current detector <NUM>, calculates the direct-current internal resistance of each of the parallel cell blocks <NUM>, and determines an non-normal battery cell by comparing a ratio of the calculated direct-current internal resistances of the parallel cell blocks <NUM> and a value of the set-value data in the set-value storage <NUM>. The current control <NUM> includes a mechanical switch or a semiconductor switch, and shuts off a charge and discharge circuit to stop charging and discharging to and from the storage battery module <NUM>-<NUM> when the calculator <NUM> determines an anomaly in the battery cells.

In the configuration described above, the storage battery module <NUM>-<NUM> is connected to an external device such as a charge and discharge device, a load, or a charger, via a positive electrode terminal TP and a negative electrode terminal TM to supply and receive electric power.

<FIG> is a diagram for explaining a detailed configuration of a BMU.

The BMU <NUM> is configured to be able to communicate with the secondary battery packs <NUM>-<NUM> to <NUM>-<NUM> via a communication line CL (see <FIG>). The BMU <NUM> includes an MPU <NUM> that controls the entire BMU <NUM>, a communication controller <NUM> that conforms to the control area network (CAN) standard to perform CAN communication with the CMUs <NUM>-<NUM> to <NUM>-<NUM>, and a memory <NUM> that stores voltage data and temperature data transmitted from the CMUs <NUM>-<NUM> to <NUM>-<NUM>.

The storage battery controller <NUM> detects electric power generated by the natural-energy power generation unit <NUM>, and controls the storage battery device <NUM> to reduce variation in the output of the generated electric power, to relieve influence of the generated electric power on the power grid. The storage battery controller <NUM> or the host control device <NUM> calculates a decrease amount of the variation for the storage battery device <NUM>, and provides it to the PCS (Power Conditioning System) <NUM> corresponding to the storage battery device <NUM> as a charge and discharge command.

As described above, the board breakers <NUM>-<NUM> to <NUM>-N correspond to the battery boards <NUM>-<NUM> to <NUM>-M.

The board breakers <NUM>-<NUM> to <NUM>-N are sequentially turned on (closed) upon startup of the storage battery system <NUM>. Thereby, the storage battery system <NUM> is connected to the main circuit, allowing the storage battery to be charged or discharged.

<FIG> is a process flowchart of an anomaly detection process in a first embodiment.

In the following, an anomaly detection operation by the CMU <NUM>-<NUM> will be described by way of example.

In this case, the voltage detector <NUM> of the CMU <NUM>-<NUM> detects voltage at predetermined timing (voltage detection timing), and outputs detected voltage data to the calculator <NUM>.

Similarly, the current detector <NUM> of the CMU <NUM>-<NUM> detects current at predetermined timing (current detection timing), and outputs detected current data to the calculator <NUM>.

Consequently, the calculator <NUM> constantly monitors variation or non-variation in the current. The calculator <NUM> detects current with no predetermined variation (before variation in the current) at certain timing (current detection timing), and stores the detected current as detected current data with no variation in the detected current (step S11).

In this case, the current value before current variation detected by the current detector <NUM> only needs to be continuously substantially constant, therefore, the current need not be limited to current in a non-conduction state. For example, a stationary large-capacity storage battery continuously charges and discharges without stop for the purpose of frequency or voltage adjustment, however, the current thereof can be used as the current before the current variation. Thus, the external device to be connected via the positive electrode terminal TP and the negative electrode terminal TM may be a charge and discharge device, a charger, or a load. In other words, there is no particular limitation to the external device as long as the environment that the conduction current of the storage battery module <NUM>-<NUM> varies is created.

Next, the calculator <NUM> detects voltage (in the example of <FIG>, detected voltages V1 to V3 corresponding to the three parallel cell blocks <NUM>) of each of the parallel cell blocks <NUM> with no current variation (before current variation) at predetermined timing (voltage detection timing), from the output of the voltage detector <NUM>, and stores the detected voltage as detected voltage data with no current variation (the detected voltages V1 to V3 in the above example)(step S12).

The calculator <NUM> then detects a variation in the current in the storage battery module <NUM>-<NUM> from the output from the current detector <NUM> (step S13).

Upon detecting the current variation, the calculator <NUM> detects the varied current (after the current variation) at predetermined timing (current detection timing), and stores the detected current as detected current data after the current variation (step S14).

Next, the calculator <NUM> detects the varied voltage (in the example of <FIG>, detected voltages V1' to V3' corresponding to the three the parallel cell blocks <NUM>) of each of the parallel cell blocks <NUM> after the current variation at predetermined timing (voltage detection timing), from the output of the voltage detector <NUM>. The calculator <NUM> then stores the detected voltage (detected voltages V1' to V3' in the above example) as detected voltage data after the current variation (step S15).

In this example, in principle the voltage detection timing and the current detection timing coincides with each other. However, the voltage detection timing and the current detection timing may shift from each other as long as the current is stable and does not vary after the current variation.

The calculator <NUM> then calculates a current variation amount ΔI by subtracting a current value corresponding to the detected current data before the current variation from a current value corresponding to the detected current data after the current variation (step S16).

The calculator <NUM> then finds differences in voltage (= V1' - V1, V2' - V2, V3' - V3) among the parallel cell blocks by subtracting the voltages V1 to V3 of the parallel cell blocks <NUM> corresponding to the detected voltage data before the current variation acquired at step S12 from the voltages V1' to V3' of the parallel cell blocks <NUM> corresponding to the detected voltage data after the current variation acquired at step S15, respectively. The calculator <NUM> then calculates a direct-current internal resistance value of each of the parallel cell blocks <NUM> by dividing the voltage difference by the current variation amount ΔI calculated by the current variation-amount calculation (step S16) (step S17).

More specifically, a direct-current internal resistance R1 of the first parallel cell block <NUM> is represented by the following formula: <MAT>.

Similarly, a direct-current internal resistance R2 of the second parallel cell block <NUM> and a direct-current internal resistance R3 of the third parallel cell block <NUM> are represented by the following formulae: <MAT> <MAT>.

The calculator <NUM> then calculates a ratio RT of the maximum value Rmax (= numerator) to the average value (= denominator) of the acquired direct-current internal resistances R1 to R3 (step S18).

More specifically, the calculator <NUM> first specifies the maximum direct-current internal resistance Rmax from the direct-current internal resistances R1 to R3 of the parallel cell blocks <NUM> calculated at step S17.

The calculator <NUM> then calculates the average value of the direct-current internal resistances = (R1 + R2 + R3)/<NUM>.

The calculator <NUM> then calculates the ratio RT of the maximum direct-current internal resistance Rmax to the average value of the direct-current internal resistances by the following formula: <MAT>.

The calculator <NUM> then compares the ratio RT and a predetermined set value A for cell anomaly detection to determine whether there is a non-normal cell (step S19).

The set value A is typically set in the range of <NUM> or more to <NUM> or less.

When the ratio RT is greater than the set value A in the determination of step S19, that is, when.

When the ratio RT is equal to or less then the set value A in the determination of step S19, that is, when.

As a result of the determination, when no non-normal cell is found and all the cells are normal, the charge and discharge operation continues.

On the other hand, when a non-normal cell is found as a result of the determination, the switch of the current control <NUM> is opened to stop charging and discharging to and from the secondary battery pack <NUM>-<NUM>, or the external device (for example, the BMU <NUM>, the PCS <NUM>, the storage battery controller <NUM>, or the host control device <NUM>) is notified of the anomaly in the secondary battery pack <NUM>-<NUM> via an information communication channel, and the external device stops the charge and discharge operation to the secondary battery pack <NUM>-<NUM>.

As described above, according to the first embodiment, the CMU <NUM>-<NUM> determines an anomaly in the parallel cell block <NUM> from the ratio RT of the maximum direct-current internal resistance Rmax to the average value of the direct-current internal resistances (R1 + R2 + R3)/<NUM>. Consequently, with presence of a battery cell with an extremely low direct-current internal resistance (battery cell with excellent performance), the CMU <NUM>-<NUM> can reduce the influence of the battery by averaging and accurately detect the parallel cell block <NUM> exhibiting a high direct-current internal resistance.

In the above, the anomaly detection of the parallel cell blocks <NUM> is described. Alternatively, it is possible to calculate the direct-current internal resistance of the storage battery modules <NUM>-<NUM> to <NUM>-<NUM> to determine a storage battery module with a high ratio as non-normal by a similar method.

<FIG> is a process flowchart of an anomaly detection process in a second embodiment.

In <FIG>, the same parts as those in <FIG> are denote by the same reference numerals.

In the first embodiment, anomaly in the parallel cell block <NUM> is determined from the ratio RT of the maximum direct-current internal resistance Rmax to the average value (R1 + R2 + R3)/<NUM> of the direct-current internal resistances. The second embodiment is different from the first embodiment in that anomaly in the parallel cell block <NUM> is determined from a ratio RT1 that is calculated on the basis of the maximum direct-current internal resistance value Rmax and the average value of the direct-current internal resistance values excluding the direct-current internal resistance value corresponding to the maximum direct-current internal resistance value Rmax among the direct-current internal resistance values R1 to R3, instead of the ratio RT of the first embodiment.

Hereinafter, different points will be mainly described.

First, the secondary battery pack <NUM>-<NUM> performs the operations from step S11 to step S17 as in the first embodiment.

The calculator <NUM> then calculates the ratio RT1 between the maximum value Rmax (= numerator) of the acquired direct-current internal resistance values R1 to R3 and the average value of the direct-current internal resistance values excluding the direct-current internal resistance value corresponding to the maximum direct-current internal resistance value Rmax among the direct-current internal resistance values R1 to R3 (step S18A).

The calculator <NUM> then calculates a value by subtracting the maximum value Rmax from the sum of the direct-current internal resistances = (R1 + R2 + R3), that is <MAT>.

More specifically, when the direct-current internal resistance R2 = Rmax, <MAT>.

The value resulting from (R1 + R2 + R3) - Rmax is the sum of the direct-current internal resistance values excluding the maximum direct-current internal resistance value Rmax.

Thus, in this case, the average value of the direct-current internal resistance values excluding the maximum direct-current internal resistance value Rmax can be found by dividing the value obtained by subtracting the maximum value Rmax from the sum of the direct-current internal resistances = (R1 + R2 + R3) by two. When the number of the direct-current internal resistance values calculated in this manner is m, the average value of the direct-current internal resistance values excluding the maximum direct-current internal resistance value Rmax can be found by dividing, by (m - <NUM>), the value found by subtracting the maximum direct-current internal resistance value Rmax from the sum of the direct-current internal resistances.

The calculator <NUM> then calculates the ratio RT1 of the maximum direct-current internal resistance Rmax to the average value of the direct-current internal resistance values excluding the maximum value Rmax by the following formula: <MAT>.

When the number of the direct-current internal resistance values calculated as above is m, the ratio RT1 of the maximum direct-current internal resistance Rmax to the average value of the direct-current internal resistance values excluding the maximum direct-current internal resistance value Rmax is calculated by the following formula: <MAT>.

The calculator <NUM> then determines whether there is an anomaly in the cells by comparing the ratio RT1 and a certain set value A for cell anomaly detection (step S19A).

When the ratio RT1 is greater than the set value A in the determination of step S19A, that is, when.

When the ratio RT1 is equal to or less than the set value A in the determination of step S19A, that is, when.

As described above, according to the second embodiment, a difference between the maximum direct-current internal resistance value Rmax and the average value of the direct-current internal resistance values excluding the direct current direct-current internal resistance value corresponding the maximum direct-current internal resistance value Rmax among the direct-current internal resistance values R1 to R3 and the maximum direct-current internal resistance value Rmax is further increased, which can further ensure detection of the parallel cell block <NUM> having a high direct-current internal resistance.

<FIG> is a process flowchart of an anomaly detection process in a third embodiment.

In <FIG>, the same parts as those in <FIG> are denoted by the same reference numerals.

In the first embodiment, an anomaly in the parallel cell block <NUM> is determined from the ratio RT of the maximum direct-current internal resistance Rmax to the average value of the direct-current internal resistance (R1 + R2 + R3)/<NUM>. The third embodiment is different from the first embodiment in that an anomaly in the parallel cell block <NUM> is determined from a ratio RT2 that is calculated on the basis of the maximum direct-current internal resistance value Rmax and a value found by dividing the average value of the direct-current internal resistance values by a standard deviation σ of the direct-current internal resistance values, instead of the ratio RT of the first embodiment.

In this example, the ratio RT2 is used for determining whether the maximum direct-current internal resistance Rmax is an outlier (a value greatly deviated from the other values) relative to the rest of the direct-current internal resistance values.

First, the secondary battery pack <NUM>-<NUM> performs the operations from step S11 to step S17 in the first embodiment.

The calculator <NUM> then calculates a standard deviation of the direct-current internal resistance values (step S18B).

More specifically, the calculator <NUM> finds the average value of the direct-current internal resistances R1 to R3 (R1 + R2 + R3)/<NUM> calculated at step S17, and calculates the standard deviation σ by the following formula.

The calculator <NUM> then calculates the ratio RT2 of the difference Rmax - (R1 + R2 + R3)/<NUM> between the maximum direct-current internal resistance Rmax and the average value relative to the calculated standard deviation σ.

The calculator <NUM> then determines whether there is an anomaly in the cells by comparing the ratio RT2 and a certain set value A for cell anomaly detection (step S19B).

When the ratio RT2 is greater than the set value A in the determination of step S19B, that is, when.

When the ratio RT2 is equal to or less than the set value A in the determination of step S19B, that is, when.

As described above, according to the third embodiment, it is possible to detect the parallel cell block <NUM> having a high direct-current internal resistance as an non-normal deviation value of the standard deviation σ that corresponds to the distribution of the direct-current internal resistance.

<FIG> is a process flowchart of an anomaly detection process in a fourth embodiment.

In the first embodiment, an anomaly in the parallel cell block <NUM> is determined from the ratio RT of the maximum direct-current internal resistance Rmax to the average value of the direct-current internal resistances (R1 + R2 + R3)/<NUM>. The fourth embodiment is different from the first embodiment in that an anomaly in the parallel cell block <NUM> is determined from a ratio RT3 that is calculated on the basis of a value found by dividing the difference between the maximum value Rmax and the average value of the direct-current internal resistance values by a standard deviation σ' of the direct-current internal resistance values excluding the maximum direct-current internal resistance value Rmax, instead of the ratio RT of the first embodiment.

The calculator <NUM> then calculates a standard deviation of the direct-current internal resistance values (step S18C).

More specifically, at step S17, the calculator <NUM> finds the average value of the direct-current internal resistance values excluding the maximum direct-current internal resistance value from the calculated sum of the direct-current internal resistances R1 to R3 (R1 + R2 + R3 - Rmax)/<NUM>, and calculates the standard deviation σ' by the following formula.

The calculator <NUM> then calculates the ratio RT3 of the difference Rmax - (R1 + R2 + R3)/<NUM> between the maximum direct-current internal resistance Rmax and the average value relative to the calculated standard deviation σ'.

The calculator <NUM> then determines whether there is an anomaly in the cells by comparing the ratio RT3 and a predetermined set value A for cell anomaly detection (step S19C).

When the ratio RT3 is greater than the set value A in the determination of step S19C, that is, when.

When the ratio RT3 is equal to or less than the set value A in the determination of step S19C, that is, when.

As described above, according to the fourth embodiment, it is possible to accurately detect the parallel cell block <NUM> having a high direct-current internal resistance as a non-normal deviation value of the standard deviation σ' that corresponds to the distribution of the direct-current internal resistances, with the influence of the maximum direct-current internal resistance removed.

<FIG> is a diagram for explaining a detailed configuration of a secondary battery pack of a fifth embodiment.

In <FIG>, the same elements as those in <FIG> are denoted by the same reference numerals.

<FIG> is different from <FIG> in the addition of a temperature detector <NUM> that detects the temperature of the storage battery module <NUM>-<NUM>.

The temperature detector <NUM> may be a single temperature sensor (temperature detector) connected to the storage battery module <NUM>-<NUM> to measure the ambient temperature of the storage battery module <NUM>-<NUM>, a plurality of temperature sensors placed inside the storage battery module <NUM>-<NUM> considering the temperature distribution in the storage battery module <NUM>-<NUM>, a temperature sensor provided in one of the battery cells <NUM> rising highest in temperature in the storage battery module <NUM>-<NUM> on the premise that the storage battery module <NUM>-<NUM> uniformly rises in temperature, or a temperature sensor used upon estimation of a temperature increase in the battery cells <NUM> according to temperature distribution.

<FIG> is a process flowchart of an anomaly detection process in the fifth embodiment.

In <FIG>, the same parts as those in <FIG> denote the same reference numerals.

In the first embodiment, the measured direct-current internal resistance values R1, R2, and R3 are used without change. The fifth embodiment is different from the first embodiment in that the measured direct-current internal resistance values R1, R2, and R3 are corrected on the basis of temperature information of the storage battery module <NUM>-<NUM> detected by the temperature detector <NUM> and determines anomaly on the basis of the corrected direct-current internal resistance values.

The calculator <NUM> then calculates, on the basis of a temperature detection signal of the storage battery module <NUM>-<NUM> output from the temperature detector <NUM>, a temperature correction for the direct-current internal resistance values R1 to R3 calculated as in the first embodiment so as to eliminate the influence of temperature (step S18D).

The temperature-correction calculation will now be described in detail.

Typically, the higher the battery temperature is, the lower the direct-current internal resistance is, and the lower the battery temperature is, the higher the direct-current internal resistance is.

In the fifth embodiment, thus, when the temperature detected by the temperature detector <NUM> (for example, <NUM> higher than the reference temperature by <NUM>) is higher than a predetermined reference temperature (for example, <NUM>), the direct-current internal resistance values R1 to R3 are corrected to smaller values at a predetermined ratio (for example, <NUM>%), or a database containing converted values of the direct-current internal resistance values relative to temperatures is pre-stored to correct the measured direct-current internal resistance values R1 to R3 referring to the database.

The calculator <NUM> then calculates the ratio RT of the maximum direct-current internal resistance Rmax to the average value of the corrected direct-current internal resistances by the following formula (step S19D1): <MAT>.

The calculator <NUM> then determines whether there is an anomaly in the cells by comparing the ratio RT and a predetermined set value A for cell anomaly detection (step S19D2).

The set value A is set in the range of <NUM> or more to <NUM> or less.

When the ratio RT is greater than the set value A in the determination of step S19D2, that is, when.

When the ratio RT is equal to or less than the set value A in the determination of step S19D2, that is, when.

As a result of the determination, when no non-normal cell is found and that all the cells are normal, the charge and discharge operation continues.

On the other hand, when a non-normal cell is found, the switch of the current control <NUM> is opened to stop charging and discharging to and from the secondary battery pack <NUM>-<NUM>, or the external device (for example, the BMU <NUM>, the PCS <NUM>, the storage battery controller <NUM>, or the host control device <NUM>) is notified of the anomaly in the secondary battery pack <NUM>-<NUM> via an information communication channel, and the external device stops the charge and discharge operation to the secondary battery pack <NUM>-<NUM>.

As described above, according to the fifth embodiment, the direct-current internal resistance values of the parallel cell blocks <NUM> are corrected on the basis of the temperature information of the storage battery module <NUM>-<NUM> from the temperature detector <NUM>, which makes it possible to more accurately detect the parallel cell block <NUM> exhibiting a high direct-current internal resistance.

<FIG> is a diagram for explaining a detailed configuration of a secondary battery pack of a sixth embodiment.

<FIG> is different from <FIG> in the addition of a temperature detector <NUM> that is connected to all the parallel cell blocks <NUM> to detect the temperature of each of the parallel cell blocks <NUM>, instead of the temperature detector <NUM> that detects the temperature of the storage battery module <NUM>-<NUM>.

<FIG> is a process flowchart of an anomaly detection process in the sixth embodiment.

In the fifth embodiment, the measured direct-current internal resistance values R1, R2, and R3 are corrected on the basis of temperature information of the storage battery module <NUM>-<NUM> detected by the temperature detector <NUM> to determine anomaly from the corrected direct-current internal resistance values. The sixth embodiment is different from the fifth embodiment in that the measured direct-current internal resistance values R1, R2, and R3 are corrected on the basis of temperature information of each parallel cell block <NUM> detected by the temperature detector <NUM> to determine anomaly from the corrected direct-current internal resistance values.

The calculator <NUM> then calculates, on the basis of a temperature detection signal of the parallel cell block <NUM> output from the temperature detector <NUM>, a temperature correction for each of the direct-current internal resistance values R1 calculated as in the first embodiment to R3, so as to eliminate the influence of temperature thereon (step S18E).

The calculator <NUM> then calculates the ratio RT of the maximum direct-current internal resistance Rmax to the average value of the corrected direct-current internal resistances (step S19E1).

The calculator <NUM> then determines whether there is an anomaly in the cells by comparing the ratio RT and a predetermined set value A for cell anomaly detection (step S19E2).

When the ratio RT is greater than the set value A in the determination of step S19E2, that is, when.

When the ratio RT is equal to or less than the set value A in the determination of step S19E2, that is, when.

As described above, according to the sixth embodiment, the direct-current internal resistance values of the parallel cell blocks <NUM> can be individually corrected on the basis of the temperature information of each of the parallel cell blocks <NUM> detected by the temperature detector <NUM>. Consequently, it is possible to more accurately detect the parallel cell block <NUM> exhibiting a high direct-current internal resistance.

<FIG> is a process flowchart of an anomaly detection process in a seventh embodiment.

In the first embodiment, the measured direct-current internal resistance values R1, R2, and R3 are used without change. The seventh embodiment is different from the first embodiment in that the measured direct-current internal resistance values R1, R2, and R3 are corrected on the basis of the voltage detected by the voltage detector <NUM>.

The calculator <NUM> then calculates, on the basis of a temperature detection signal of each parallel cell block <NUM> output from the temperature detector <NUM>, a voltage correction for each of the direct-current internal resistance values R1 to R3 calculated as in the first embodiment so as to eliminate the influence of voltage of each of the parallel cell blocks <NUM> detected by the voltage detector <NUM> (step S18F).

The calculator <NUM> then calculates the ratio RT of the maximum direct-current internal resistance Rmax to the average value of the corrected direct-current internal resistances (step S19F1).

The calculator <NUM> then determines whether there is an anomaly in the cells by comparing between the ratio RT and a predetermined set value A for cell anomaly detection (step S19F2).

When the ratio RT is greater than the set value A in the determination of step S19F2, that is, when.

When the ratio RT is equal to or less then the set value A in the determination of step S19F2, that is, when.

As described above, according to the seventh embodiment, the direct-current internal resistance values of the parallel cell blocks <NUM> can be individually accurately corrected in accordance with the voltage detected by the voltage detector <NUM>. Consequently, it is possible to more accurately detect the parallel cell block <NUM> exhibiting a high direct-current internal resistance. Eighth Embodiment.

<FIG> is a process flowchart of an anomaly detection process in an eighth embodiment.

In the first embodiment, the measured direct-current internal resistance values R1, R2, and R3 are used without change. The eighth embodiment is different from the first embodiment in that the direct-current internal resistances are corrected in accordance with the remaining amount of the batteries (state of charge (SOC)) of the storage battery module <NUM>-<NUM>.

The current detector <NUM> detects the charge and discharge currents of the storage battery module <NUM>-<NUM>, and thus the SOC can be calculated by integrating the charge and discharge currents.

Meanwhile, the direct-current internal resistance value varies depending on a difference in the SOC. Thus, the current detector <NUM> detects the charge and discharge currents of the storage battery module <NUM>-<NUM> and the charge and discharge currents of the parallel cell blocks <NUM>. The calculator <NUM> calculates the SOC of each of the parallel cell blocks <NUM> by integrating the detected charge and discharge currents.

The calculator <NUM> thus corrects the direct-current internal resistances using the calculated SOC.

The calculator <NUM> then calculates the SOC by integrating the charge and discharge currents of the storage battery module <NUM>-<NUM> output from the current detector <NUM>, and individually corrects the direct-current internal resistance values R1 to R3 calculated on the basis of the calculated SOC (step S18G).

The calculator <NUM> then calculates the ratio RT of the maximum direct-current internal resistance Rmax to the average value of the corrected direct-current internal resistance by the following formula (step S19G1): <MAT>.

The calculator <NUM> then determines whether there is an anomaly in the cells by comparing the ratio RT and a predetermined set value A for cell anomaly detection (step S19G2).

When the ratio RT is greater than the set value A in the determination of step S19G2, that is, when.

When the ratio RT is equal to or less than the set value A in the determination of step S19G2, that is, when.

On the other hand, a non-normal cell is found as a result of the determination, the switch of the current control <NUM> is opened to stop charging and discharging to and from the secondary battery pack <NUM>-<NUM>, or the external device (for example, the BMU <NUM>, the PCS <NUM>, the storage battery controller <NUM>, or the host control device <NUM>) is notified of the anomaly in the secondary battery pack <NUM>-<NUM> via an information communication channel, and the external device stops the charge and discharge operation to the secondary battery pack <NUM>-<NUM>.

As described above, according to the eighth embodiment, the SOC is found from the current information obtained by the current detector <NUM> to accurately correct the direct-current internal resistance value of each of the parallel cell blocks <NUM>. Thereby, accurate detection of the parallel cell block <NUM> exhibiting a high direct-current internal resistance is feasible.

<FIG> is a process flowchart of an anomaly detection process in a ninth embodiment.

In the first embodiment, the measured direct-current internal resistance values R1, R2, and R3 are used without change. The ninth embodiment is different from the first embodiment in that the direct-current internal resistances are corrected in accordance with current values of the charge and discharge currents.

Along with a change in the charge and discharge currents from charge to discharge or from discharge to charge, batteries may show hysteresis characteristics in the voltage curve called open circuit voltage (OCV) and closed circuit voltage (CCV), and as a result, they may excessively vary in voltage.

Thus, in the ninth embodiment, the current detector <NUM> detects the charge and discharge currents of the storage battery module <NUM>-<NUM> and the charge and discharge currents of the parallel cell blocks <NUM>, and the calculator calculates a correction for the variation in the direct-current internal resistance value of each of the parallel cell blocks <NUM> on the basis of the detected current values.

The calculator <NUM> then corrects each of the direct-current internal resistance values R1 to R3 calculated on the basis of the charge and discharge currents of the storage battery module <NUM>-<NUM> output from the current detector <NUM> (step S18H).

The calculator <NUM> then calculates the ratio RT of the maximum direct-current internal resistance Rmax to the average value of the corrected direct-current internal resistances (step S19H1).

The calculator <NUM> then determines whether there is an anomaly in the cells by comparing the ratio RT and a predetermined set value A for cell anomaly detection (step S19H2).

When the ratio RT is greater than the set value A in the determination of step S19H2, that is, when.

When the ratio RT is equal to or less than the set value A in the determination of step S19H2, that is, when.

According to the ninth embodiment described above, the direct-current internal resistance values of the parallel cell blocks <NUM> are accurately corrected in accordance with the current values detected by the current detector <NUM> to accurately detect the parallel cell block <NUM> exhibiting a high direct-current internal resistance.

While some embodiments of the invention have been described, these embodiments are merely examples, and are not intended to limit the scope of the invention which is defined by the appended claims.

Claim 1:
A battery monitoring device (<NUM>-<NUM>~<NUM>-<NUM>) configured to monitor a state of a secondary battery block (<NUM>-<NUM>~<NUM>-<NUM>) including a plurality of parallel cell blocks (<NUM>) connected in series, the parallel cell blocks (<NUM>) each including a plurality of battery cells (<NUM>) connected in parallel, the battery monitoring device (<NUM>-<NUM>~<NUM>-<NUM>), comprising:
a current detector (<NUM>) configured to detect current flowing through each of the parallel cell blocks(<NUM>);
a voltage detector (<NUM>) configured to detect voltage of each of the parallel cell blocks (<NUM>) when the current flowing through the parallel cell block (<NUM>) is a first current value, and when the current flowing through the parallel cell block (<NUM>) is a second current value;
a calculator (<NUM>) configured to calculate a direct-current internal resistance value of each of the parallel cell blocks (<NUM>) on the basis of a differential current between the first current value and the second current value, the voltage of the parallel cell block at the first current value, and the voltage of the parallel cell block (<NUM>) at the second current value; and
a determiner (<NUM>-<NUM>~<NUM>-<NUM>) configured to perform anomaly determination for the parallel cell blocks on the basis of direct-current internal resistance values of the parallel cell blocks (<NUM>) and a maximum value (Rmax) of the direct-current internal resistance values of the parallel cell blocks
characterized in that
the calculator (<NUM>) is configured to calculate a first standard deviation of all of the direct-current internal resistance values, and
the determiner (<NUM>-<NUM>~<NUM>-<NUM>) is configured to determine, based on the first standard deviation, that there is an anomaly in the parallel cell block (<NUM>) when the maximum value (Rmax) is an outlier relative to the rest of the direct-current internal resistance values (R1~R3).