JP7668144B2 - Voltage Generator - Google Patents

Description

The present invention relates to a voltage generating device, for example, a voltage generating device capable of generating a voltage that simulates the voltage behavior of a battery cell.

Generally, a battery consists of a battery cell consisting of a single cell, a battery module in which multiple battery cells are connected in series and/or parallel, and a battery pack in which multiple battery modules are housed in a single container.

A battery management system (BMS) monitors the voltage state of each of the multiple battery cells installed in a battery module or a battery pack, and prevents some battery cells from overcharging or over-discharging, thereby preventing battery cell fires and extending the life of the battery pack.

Battery management systems can be configured in a one-box configuration consisting of a battery pack and one battery management system board (BMS board) for this battery pack, or in a modular configuration consisting of a BMS board for each battery module and a control board that oversees them.

For example, Patent Document 1 describes, as an example of a battery management system, a cell balancing system that can perform cell balancing so that each battery cell has an appropriate voltage via a switch individually provided in each battery cell.

Special table 2019-503640 publication

To ensure long-term, safe use of the battery, it is important that the battery management system operates properly.

Conventionally, to verify that a battery management system was operating normally, a method was used in which a voltage equivalent to the voltage of each battery cell in a battery pack or battery module was generated, and the current and voltage input to the battery management system were observed.

However, the inspection device used in the conventional method for inspecting battery management systems only generates a voltage based on a voltage value that corresponds to the battery cell voltage set by an operator. In other words, the conventional inspection device was not able to generate a voltage by simulating the voltage behavior of the battery cell by itself. In particular, the conventional inspection device was not able to simulate the voltage behavior of the battery cell according to the load on the battery pack or battery module.

The present invention has been made in consideration of the above-mentioned problems in the conventional technology, and the objective of the present invention is to provide a voltage generating device that can generate a voltage that simulates the voltage behavior of a battery cell according to the load on the battery pack.

A voltage generating device according to a representative embodiment of the present invention includes a relational equation acquisition unit that acquires a relational equation indicating the relationship between the remaining capacity of a battery cell and the terminal voltage value, which is generated based on a measurement value pair consisting of a remaining capacity of a battery cell and a measurement value of the terminal voltage value of the battery cell at that remaining capacity, a voltage value calculation unit that calculates the terminal voltage value corresponding to the input remaining capacity of the battery cell based on the relational equation, and a voltage generation unit that generates a voltage according to the terminal voltage value calculated by the voltage value calculation unit.

The voltage generating device according to the present invention can generate a voltage that simulates the voltage behavior of a battery cell according to the load on the battery pack.

1 is a diagram showing a schematic configuration of a voltage generating system 1 including a voltage generating device 200 according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a specific configuration example of a voltage generating device 200. 4 is a diagram for explaining a relational expression showing the relationship between the remaining capacity of a battery cell and the inter-terminal voltage value. FIG. 10 is a diagram for explaining the relationship between a load current value, a charge/discharge current value, and a cell balancing current. FIG. 2 is a sequence diagram showing the flow of processing between a computer 100 and a voltage generating device 200 in a voltage generating system 1. FIG. FIG. 11 is a flowchart showing a detailed process flow of a voltage generation process. FIG. 11 is a diagram showing a schematic configuration of an MCU 212 of a data processing control unit in a voltage generating device 200 according to a second embodiment. 4 is a diagram for explaining a relational expression showing the relationship between the remaining capacity of a battery cell and the inter-terminal voltage value. FIG. 2 is a sequence diagram showing the flow of processing between a computer 100 and a voltage generating device 200 in a voltage generating system 1. FIG. FIG. 4 is a flowchart showing a detailed process flow of a voltage generation process. FIG. 13 is a diagram showing that different relational expressions are used in the case of charging and in the case of discharging.

1. Overview of the embodiment First, an overview of a representative embodiment of the invention disclosed in this application will be described. Note that in the following description, as an example, reference numerals in the drawings corresponding to components of the invention are given in parentheses.

[1] A voltage generating device (200) according to a representative embodiment includes a relational equation acquisition unit (213) that acquires a relational equation indicating the relationship between the remaining capacity of a battery cell and the terminal voltage value generated based on a measurement value pair consisting of a remaining capacity of a battery cell and a measurement value of the terminal voltage value of the battery cell at that remaining capacity, a voltage value calculation unit (219) that calculates the terminal voltage value corresponding to the input remaining capacity of the battery cell based on the relational equation, and a voltage generation unit (222) that generates a voltage according to the terminal voltage value calculated by the voltage value calculation unit.

According to this aspect, the terminal voltage value is calculated based on a relational expression that indicates the relationship between the remaining capacity of the battery cell, which is generated based on the measurement value pair, and the terminal voltage value, so that the calculated terminal voltage value indicates the relationship between the actual remaining capacity of the battery cell and the terminal voltage value. By generating a voltage according to the calculated terminal voltage value, it is possible to generate a voltage that simulates the voltage behavior of the battery cell according to the load on the battery pack.

[2] The voltage generating device according to the above [1] further includes a capacity value calculation unit that calculates the remaining capacity based on a load current value, which is a value of a current output from the battery cell, and an elapsed time,
The voltage value calculation unit may calculate a terminal-to-terminal voltage value corresponding to the remaining capacity calculated by the capacity value calculation unit.

According to this aspect, it is possible to generate a voltage that simulates the change in the voltage behavior of a battery cell over time.

[3] In the voltage generating device described in [2] above, the load current value may be the sum of a charge/discharge current value flowing through a load connected to the battery cell and a cell balancing current value that is a current input/output to equalize the inter-terminal voltage value between the battery cell and other battery cells.

According to this aspect, the voltage behavior of the simulated battery cell can be made to reflect the effects of both the charge/discharge current flowing through the load connected to the battery and the cell balancing current.

[4] The voltage generating device described in [3] above may further include an external terminal connected to the outside and outputting the voltage generated by the voltage generating unit to the outside, and a current measuring unit measuring a current flowing through the external terminal, and the capacitance value calculation unit may take the current value measured by the current measuring unit as the cell balancing current value.

According to this embodiment, the cell balancing current value actually measured can be used, so the effect of the operation of the cell balancing function of the BMS can be reflected in the voltage behavior of the simulated battery cell.

[5] In the voltage generating device described in any one of [1] to [4] above, the relational equation acquired by the relational equation acquisition unit may be an equation based on a function obtained by linearly interpolating between two pairs of the measurement values.

This aspect makes it easy to generate locally appropriate relational expressions.

[6] In the voltage generating device according to any one of [1] to [4] above, the relational expression acquired by the relational expression acquisition unit may be a polynomial.

This eliminates the need to generate a relational equation each time a voltage value is calculated.

[7] In the voltage generating device described in [5] above, the relational equation acquisition unit may have an input unit that accepts input of the measurement value pairs, and a relational equation generation unit that generates the relational equation based on the input measurement value pairs.

According to this aspect, the relational equation acquisition unit generates a relational equation based on a pair of measured values, so that the voltage generating device can handle everything from generating the relational equation to generating the voltage.

[8] A representative embodiment of a voltage generation system (1) is a voltage generation system including the voltage generation device described in [6] above and a computer, the computer having an input unit that accepts input of the measurement value pairs and a relational equation generation unit that generates the relational equation based on the input measurement value pairs, and the relational equation acquisition unit acquires the relational equation generated by the computer.

According to this aspect, the relational equation acquisition unit acquires a relational equation generated by a computer, so that processing can be performed by a voltage generating device that is not configured to generate a relational equation.

[9] A voltage generation program according to a representative embodiment is a voltage generation program for causing a computer to realize a relational equation acquisition function that acquires a relational equation indicating the relationship between the remaining capacity of a battery cell and the terminal voltage value, which is generated based on a measurement value pair consisting of the remaining capacity of a battery cell and a measurement value of the terminal voltage value of the battery cell at that remaining capacity, a voltage value calculation function that calculates the terminal voltage value corresponding to the input remaining capacity of the battery cell based on the relational equation, and a voltage generation function that generates a voltage according to the terminal voltage value calculated by the voltage value calculation function.

According to this aspect, the terminal voltage value is calculated based on a relational expression that indicates the relationship between the remaining capacity of the battery cell, which is generated based on the measurement value pair, and the terminal voltage value, so that the calculated terminal voltage value indicates the relationship between the actual remaining capacity of the battery cell and the terminal voltage value. By generating a voltage according to the calculated terminal voltage value, it is possible to generate a voltage that simulates the voltage behavior of the battery cell according to the load on the battery pack.

[10] A voltage generation method according to a representative embodiment includes a relational equation acquisition step of acquiring a relational equation indicating the relationship between the remaining capacity of a battery cell and the terminal voltage value, which is generated based on a measurement value pair consisting of a remaining capacity of a battery cell and a measurement value of the terminal voltage value of the battery cell at that remaining capacity; a voltage value calculation step of calculating the terminal voltage value corresponding to the input remaining capacity of the battery cell based on the relational equation; and a voltage generation step of generating a voltage according to the terminal voltage value calculated by the voltage value calculation step.

According to this aspect, the terminal voltage value is calculated based on a relational expression that indicates the relationship between the remaining capacity of the battery cell, which is generated based on the measurement value pair, and the terminal voltage value, so that the calculated terminal voltage value indicates the relationship between the actual remaining capacity of the battery cell and the terminal voltage value. By generating a voltage according to the calculated terminal voltage value, it is possible to generate a voltage that simulates the voltage behavior of the battery cell according to the load on the battery pack.

2. Specific Examples of the Embodiments Specific examples of the embodiments of the present invention will be described below with reference to the drawings. In the following description, components common to each embodiment are given the same reference numerals, and repeated description will be omitted. Also, the drawings are schematic, and the dimensional relationship between each element, the ratio between each element, etc. may differ from reality.

(First embodiment)
FIG. 1 is a diagram showing a schematic configuration of a voltage generating system 1 including a voltage generating device 200 according to the first embodiment.

The voltage generation system 1 shown in FIG. 1 can be used, for example, to inspect a battery management system (hereinafter, simply referred to as "BMS"). Here, the BMS is, for example, a device that monitors the voltage state of each of multiple battery cells mounted in a battery pack, as described above, and prevents some of the battery cells from being overcharged or overdischarged.

The voltage generating device 200 constituting the voltage generating system 1 generates (simulates) a voltage that mimics the voltage behavior of a battery cell. In particular, the voltage generating device 200 is capable of generating a voltage that mimics the voltage behavior of a battery cell in a steady state.

As shown in FIG. 1, the voltage generation system 1 of this embodiment includes a computer (information processing device) 100 and a voltage generation device 200 connected to the computer 100. The voltage generation system 1 inspects the BMS 300 with the voltage generation device 200 connected to the BMS 300.

The computer 100 is, for example, a personal computer (PC). Note that the computer 100 only needs to be capable of performing data communication with the voltage generating device 200, and may be, for example, a portable information processing device such as a tablet terminal.

For example, when a user inputs necessary information to computer 100, voltage generating device 200 executes the control described below according to the information input to computer 100, causing voltage generating device 200 to generate a voltage simulating a battery cell. This voltage simulating a battery cell is applied to the connected BMS 300, and BMS 300 performs a predetermined operation according to the applied voltage. A user can inspect BMS 300 by observing the behavior of BMS 300 when a voltage simulating a battery cell is applied.

Figure 2 shows a specific example configuration of the voltage generating device 200.

The specific configuration of the voltage generation system 1 will be described with reference to Figure 2.

As shown in FIG. 2, the computer 100 includes a display unit 101, a processing unit 102, and an input/output unit 103.

When the computer 100 receives a predetermined input from a user at the input/output unit 103, the computer 100 performs the predetermined input to the voltage generating device 200. Specifically, when the input/output unit 103 of the computer 100 receives input of a measurement value pair and a charge/discharge current value measured in advance by a charge/discharge tester when generating a voltage, the input/output unit 103 of the computer 100 transmits these values to the voltage generating device 200.

A measurement value pair is a combination of a remaining capacity of a battery cell and a measured value of the terminal voltage value of the battery cell at that remaining capacity. In one example, the measurement value pair is input by a user who has previously measured the measurement value pair using a charge/discharge tester, but the measurement method of the measurement value pair is not limited to this. The measurement value pair may be measured frequently where the change in the terminal voltage value is large, and measured at large intervals where the change is small. In addition, the measurement value pair is not limited to the measured value, and a set of multiple measurement value pairs may be stored in advance in a storage unit (not shown) in the computer 100, and the user may select a set of measurement value pairs to be used for simulation. The number of combinations of measurement value pairs required is preset in the storage unit of the computer 100, and the processing unit 102 may prompt the input of the set number. In this case, an upper limit may be set on the number of measurement value pairs to comply with the limitations of the internal memory capacity.

In addition, in the computer 100, the processing unit 102 can process data received from the voltage generating device 200 and display it on the display unit 101. The display unit 101 is, for example, a display device such as a liquid crystal display or a touch panel. For example, the processing unit 102 receives measurement data such as the change over time of the current value measured by the current measuring unit 223 described below and the change over time of the voltage value measured by the voltage measuring unit 224, and generates display data based on the received measurement data and outputs it to the display unit 101. This makes it possible to display graphs showing the change over time of the voltage and the change over time of the current on the display unit 101. The user can check the output of the voltage generating system by observing the graphs displayed on the display unit 101.

The voltage generating device 200 includes a plurality of cell voltage generating units 220_1 to 220_n connected to the plurality of channels of the BMS 300, respectively, and a data processing control unit 210 connected to each of the plurality of cell voltage generating units 220_1 to 220_n. In the following description, when there is no need to distinguish between the cell voltage generating units 220_1 to 220_n, they may simply be referred to as "cell voltage generating units 220."

The data processing control unit 210 uses values and instructions received from the computer 100 to calculate the voltage values to be generated by each cell voltage generating unit 220, and outputs them to each of the multiple cell voltage generating units 220.

The multiple cell voltage generating units 220 generate and output voltages for each channel of the connected BMS 300 according to the voltage values received from the data processing control unit 210.

Each of the multiple cell voltage generating units 220_1 to 220_n is provided with a connection terminal 25_1 to 225_n for connecting to the BMS 300.

The cell voltage generating units 220_1 to 220_n include voltage generating units 222_1 to 222_n, current measuring units 223_1 to 223_n, voltage measuring units 224_1 to 224_n, and connection terminals 225_1 to 225_n. In the following description, when the voltage generating units 222_1 to 222_n, current measuring units 223_1 to 223_n, voltage measuring units 224_1 to 224_n, and connection terminals 225_1 to 225_n are not distinguished from one another, they may be simply referred to as "communication unit 221", "voltage generating unit 222", "current measuring unit 223", "voltage measuring unit 224", and "connection terminal 225". The voltage generating unit 222 can be configured using a known voltage generating means such as a D/A converter or an amplifier, and the configuration is not particularly limited. The current measurement unit 223 can be configured using known current measurement means such as an A/D converter or resistor, and the configuration is not particularly limited. The voltage measurement unit 224 can be configured using known voltage measurement means such as an A/D converter or resistor, and the configuration is not particularly limited.

The voltage value calculated by the data processing control unit 210 is input to the voltage generation unit 222. Meanwhile, the current and voltage measured by the current measurement unit 223 and the voltage measurement unit 224 (changes in the current value over time and the voltage value over time) are passed to the output unit 226 of the data processing control unit 210.

The data processing control unit 210 has a LAN interface (Local Area Network interface) and a program processing device 211. The program processing device 211 is a microcontroller (MCU) that has hardware elements such as a processor such as a CPU, various memories such as ROM and RAM, a timer (counter), an A/D conversion circuit, an input/output I/F circuit, and a clock generation circuit, and each component is connected to each other via a bus or a dedicated line. Hereinafter, the program processing device 211 is also referred to as the MCU 211.

2, the MCU 211 includes, as functional units for calculating voltage values simulating a battery cell, a relational equation acquisition unit 213 having a relational equation generation unit 215 and a measurement value pair input unit 214, a charge/discharge current value input unit 217, a capacity value calculation unit 218, a voltage value calculation unit 219, and an output unit 226. Each of these functional units can be realized, for example, by the processor of the MCU 211 performing various calculations according to programs stored in a memory or the like, and controlling peripheral circuits such as an A/D conversion circuit and an input/output I/F circuit.

The relational equation acquisition unit 213 has a measurement value pair input unit 214 and a relational equation generation unit 215, and acquires a relational equation indicating the relationship between the remaining capacity of the battery cell and the inter-terminal voltage value based on the measurement value pair. The measurement value pair input unit 214 accepts input of the measurement value pair from the computer 100 via the LAN, and provides it to the relational equation generation unit 215 and the capacity value calculation unit 218.

The relational equation generating unit 215 generates a relational equation that indicates the relationship between the remaining capacity of the battery cell and the inter-terminal voltage value based on the measurement value pair received from the measurement value pair input unit 214. This relational equation will be explained based on FIG. 3.

Figure 3 is a diagram explaining the relationship between the remaining capacity of a battery cell and the terminal voltage value.

In FIG. 3, the remaining capacity of the battery cell is shown on the horizontal axis, and the terminal voltage value is shown on the vertical axis, with multiple measurement value pairs plotted along these vertical and horizontal axes. Furthermore, adjacent plots of the measurement value pairs in FIG. 3 are linearly interpolated. The relational equation generated by the relational equation generating unit 215 of this embodiment is an equation expressed as a function that linearly interpolates between adjacent plots.

The relational equation generating unit 215 performs linear interpolation by, for example, connecting the two plots with a straight line and generating a function y = ax + b, where the slope of the line is a and the intercept is b. In this function, x indicates the remaining capacity of the battery cell, and y indicates the terminal voltage value.

The relational equation acquisition unit 213 provides the generated relational equation to the voltage value calculation unit 219.

The charge/discharge current value input unit 217 accepts input of charge/discharge current values from the computer 100 via the LAN and provides the values to the capacity value calculation unit 218.

The capacity value calculation unit 218 calculates the increase or decrease in the remaining capacity of the battery cell based on the load current value, which is the value of the current output from the battery cell, and the elapsed time. This load current value is the sum of the charge/discharge current value flowing through the load connected to the battery, and the cell balancing current value, which is the current input/output to equalize the terminal voltage between the battery cells and other battery cells. Here, the cell balancing current value is explained.

Figure 4 is a diagram to explain the relationship between the load current value, the charge/discharge current value, and the cell balancing current.

4 shows an example of a usage state of a battery management system including a plurality of battery cells 10 ₁ to 10 ₁₂ (hereinafter, simply referred to as "battery cells 10") and a BMS 300. In the usage state, a load 400 and the BMS 300 are connected in parallel to the battery cells 10, and current is input to and output from the load 400 and the BMS 300.

Each battery cell 10 discharges from the load 400 to operate the load 400 (charging/discharging current is -IL) or receives regenerative power from the load 400 and charges it (charging/discharging current is IL), so that the battery cell 10 inputs and outputs current to the load 400.

In order to equalize the terminal voltages of the battery cells 10, the multiple battery cells _10-1 to _10-12 pass a current from a battery cell 10 having a higher terminal voltage to a battery cell 10 having a lower terminal voltage. This current for equalizing the terminal voltages flows via the BMS 300. When each battery cell 10 discharges to another battery cell, a cell balancing current -IB flows to the BMS 300, and when each battery cell 10 is charged from another battery cell, the cell balancing current IB flows to the BMS 300.

As shown in FIG. 4, if the load current value, which is the value of the current output from the battery cell 10, is expressed as Io, it can be seen that there is a relationship of Io = IL + IB.

Returning to FIG. 2, specifically, the capacity value calculation unit 218 calculates the increase or decrease in the remaining capacity of the battery cell based on the charge/discharge current value provided by the charge/discharge current value input unit 217, the current value measured by the current measurement unit 223 described below, and the elapsed time. The capacity value calculation unit 218 further calculates the remaining capacity of the battery cell for each elapsed time by adding or subtracting the increase or decrease in the remaining capacity of the battery cell calculated from the remaining capacity of the first battery cell. The remaining capacity of the first battery cell can be said to be the voltage value corresponding to the first plot of the measurement value pair.

The capacity value calculation unit 218 calculates the current integrated value, which is the integrated value of the load current, by multiplying the load current value, which is the value of the current output from the battery cell, by the elapsed time. When simulating charging, the remaining capacity of the initial battery cell is empty, so this integrated value becomes the remaining capacity. When simulating discharging, the remaining capacity can be calculated by subtracting this current integrated value from the capacity when fully charged.

In the capacity value calculation unit 218 of the voltage generation system 1 of this embodiment, the calculation of the remaining capacity of the battery cell can be performed every time equivalent to one period of the power supply frequency (1 PLC: Power Line Cycle), but is not limited to this. If the capacity value calculation unit 244 performs calculations at 1 PLC intervals, for example, with a 50 Hz power supply, 1 PLC is 20 ms, so the remaining capacity of the battery cell can be calculated with an elapsed time of 20 ms.

The capacity value calculation unit 218 provides the remaining capacity of the battery cell for each calculated elapsed time to the voltage value calculation unit 219.

Based on the relational equation provided by the relational equation acquisition unit 213, the voltage value calculation unit 219 calculates the terminal-to-terminal voltage value of the battery cell corresponding to the remaining capacity of the battery cell provided by the capacity value calculation unit 218, and provides this to the voltage generation unit 222 of the cell voltage generation unit 220. At the start of the simulation, the voltage value calculation unit 219 provides the voltage value corresponding to the first plot of the measurement value pair as the terminal-to-terminal voltage value of the battery cell to the voltage generation unit 222 of the cell voltage generation unit 220.

In the cell voltage generating unit 220, the voltage generating unit 222 generates a voltage according to the voltage value received from the voltage value calculating unit 219. The voltage generating unit 222 is connected to a connection terminal 225 for connecting to the BMS 300, and the voltage generated by the voltage generating unit 222 is output to the BMS 300.

In addition, since the current measuring unit 223 is also connected to the connection terminal 225 connected to the BMS 300, the current measuring unit 223 can measure the current at the connection terminal 225. Information on the current measured by the current measuring unit 223 is transmitted to the capacity value calculation unit 218 and the output unit 226 of the data processing control unit 210.

Furthermore, since the voltage measurement unit 224 is also connected to the connection terminal 225 connected to the BMS 300, the voltage measurement unit 224 can measure the voltage at the connection terminal 225. Information on the voltage measured by the voltage measurement unit 224 is transmitted to the output unit 226 of the data processing control unit 210.

The measured current and voltage information (changes in current value over time and changes in voltage value over time) sent to the output unit 226 is sent to the processing unit 102 of the computer 100 as measurement data.

Next, the operation of the voltage generation system 1 will be described.

Figure 5 is a sequence diagram showing the processing flow between the computer 100 and the voltage generating device 200 in the voltage generating system 1.

First, in the computer 100, the processing unit 102 receives a pair of measurement values input by the user via the input/output unit 103 (step S101). The pair of measurement values is input by the user having previously measured the pair of measurement values using a charge/discharge tester. The processing unit 102 provides the received pair of measurement values to the voltage generating device 200.

Similarly, in the computer 100, the processing unit 102 accepts input of a charge/discharge current value from a user via the input/output unit 103 (step S102). The processing unit 102 provides the accepted charge/discharge current value to the voltage generating device 200. The processing unit 102 also accepts input of an execution instruction to generate a voltage (step S103).

In response to the execution instruction of step S103, the voltage generating device 200 executes a voltage generation process based on the measurement value pairs and the charge/discharge current values received from the computer 100 (step S200). The flow of the voltage generation process will be described in detail below.

Figure 6 is a flow diagram showing the detailed process flow of the voltage generation process. (Simulation starts)

In the voltage generating device 200, when the capacity value calculation unit 218 starts the voltage generation process, the capacity value calculation unit 218 sets the voltage value corresponding to the first plot of the measurement value pair as the initial value (step S201). At this time, the voltage value calculation unit 219 also provides the voltage value corresponding to the first plot of the measurement value pair to the voltage generation unit 222 of the cell voltage generation unit 220 as the inter-terminal voltage value of the battery cell, and the voltage corresponding to the first plot is output from the connection terminal 225. The relational equation generation unit 215 calculates a linear equation by connecting the initial value and the next plot (step S202).

Next, the current measurement unit 223 performs current measurement and provides the measured current value (cell balancing current value) to the capacity value calculation unit 218 (step S203).

The capacity value calculation unit 218 multiplies the sum of the charge/discharge current value and the cell balancing current value by the elapsed time to calculate the current capacity of the battery, calculates the current remaining capacity value, and provides the calculated remaining capacity value to the voltage value calculation unit 219 (step S204).

The voltage value calculation unit 219 substitutes the received remaining capacity into the relational equation to calculate the terminal voltage value (hereinafter simply referred to as the "voltage value") (step S205).

The voltage value calculation unit 219 determines whether the output voltage calculated this time is equal to the voltage value calculated last time (step S206), and if it determines that they are not equal (step S206: No), it changes the voltage value to be provided to the voltage generation unit 222 to the calculated voltage value (step S208). Changing the voltage value to be provided to the voltage generation unit 222 changes the voltage generated by the voltage generation unit 222.

The capacity value calculation unit 218 determines whether the remaining capacity value calculated in step S204 is smaller than the remaining capacity of the next plot (step S209). If the remaining capacity value calculated in step S204 is smaller than the remaining capacity of the next plot (step S209: Yes), there is no need to change the relational expression, so the capacity value calculation unit 218 returns to the current measurement in step S203 and calculates the remaining capacity.

On the other hand, if the remaining capacity value calculated in step S204 is not smaller than the remaining capacity of the next plot (step S208: No), the relational equation needs to be changed, so the capacitance value calculation unit 218 determines whether there is a measurement value pair for the next plot (step S209), and if there is not a measurement value pair for the next plot (step S209: No), ends the voltage generation process. If there is a measurement value pair for the next plot (step S209: Yes), the capacitance value calculation unit 218 notifies the relational equation acquisition unit 213 of this fact. In the relational equation acquisition unit 213 that has received the notification, the relational equation generation unit 215 calculates a linear equation by connecting the next plot in the current linear equation with the plot after that (step S210).

Second Embodiment
In the voltage generating system 1 of the first embodiment, a function obtained by linearly interpolating the measured value pairs is used as a relational expression to calculate the voltage value, but in the voltage generating system 1 of the present embodiment, a function obtained by expressing the measured value pairs as a polynomial is used as a relational expression to calculate the voltage value. In the first embodiment, the data processing control unit 210 in the voltage generating device 200 calculates the relational expression in the MCU 211, but in the present embodiment, the data processing control unit 210 in the voltage generating device 200 acquires the relational expression calculated by the computer 100. Therefore, the configuration for generating the relational expression is different from the configuration for calculating the voltage value using the acquired relational expression. Specifically, the functional configuration of the data generated by the PC and the MCU 212 (see FIG. 7) in the data processing control unit 210 is mainly different, but the other configurations are common, so a description of the configuration of the common parts will be omitted.

Figure 7 is a diagram showing the schematic configuration of the MCU 212 of the data processing control unit in the voltage generating device 200 according to the second embodiment.

In this embodiment, the computer 100 is equipped with a display unit 101, a processing unit 102, and an input/output unit 103, as in FIG. 2, and these components are configured to cooperate to function as a measurement value pair input unit 110 and a relational equation generation unit 120.

As in the first embodiment, in one example, the measured value pair input unit 110 receives values measured in advance by the user using a charge/discharge tester, but the measurement method for the measured value pair is not limited to this. The measured value pairs may be measured in detail where the change in the terminal voltage value is large, and measured at large intervals where the change is small. Furthermore, the measured value pairs are not limited to measured values, and a set of multiple measured value pairs may be stored in advance in a storage unit (not shown), and the user may select a set of measured value pairs to be used for simulation. The required number of combinations of measured value pairs is preset in the measured value pair input unit 110, and the input of the set number may be prompted. In this case, an upper limit may be set on the number of measured value pairs to comply with the limitations of the internal memory capacity.

The relational equation generating unit 120 generates a relational equation that indicates the relationship between the remaining capacity of the battery cell and the inter-terminal voltage value based on the measurement value pair received from the measurement value pair input unit 110. This relational equation will be explained with reference to FIG. 8.

Figure 8 is a diagram explaining the relationship between the remaining capacity of a battery cell and the terminal voltage value.

In FIG. 8, the remaining capacity of the battery cell is shown on the horizontal axis, the inter-terminal voltage value is shown on the vertical axis, and multiple measurement value pairs are plotted. In this embodiment, the plot of the measurement value pairs is approximated by a polynomial, as shown in FIG. 8.

The relational equation generating unit 120 can generate, for example, a polynomial expressed as y= _C1I9 + ^C2I8 +... _C9I + _C10 as a relational equation using ^a _minimum 2 information, singular point decomposition algorithm, etc. In this polynomial, _C1 ... _C10 are arbitrary coefficients, I is the remaining capacity of the battery cell, and y is the terminal voltage value.

The relational equation generating unit 120 may use other algorithms for approximation, not limited to the polynomial shown in Fig. 8. For example, _in y = _C1F1 (x) + _C2F2 (x) + ... _{Cn-1Fn -1 (} x), an n-dimensional linear curve defined as _F1 (x) = sinx, _F2 (x) = cosx, Fn _-1 (x) = 1/( ^x2 + 1) or the like may be used. The relational equation generating unit 120 provides the generated relational equation to the relational equation acquiring unit 241.

Returning to FIG. 7, the MCU 211 of the data processing control unit 210 includes a relational equation acquisition unit 241, a charge/discharge current value input unit 243, a capacity value calculation unit 244, and a voltage value calculation unit 245 as functional units for calculating voltage values simulating a battery cell. Each of these functional units can be realized, for example, by the processor of the MCU 211 performing various calculations according to programs stored in a memory or the like, and controlling peripheral circuits such as an A/D conversion circuit and an input/output I/F circuit.

The relational equation acquisition unit 241 acquires the relational equation generated by the computer 100 and provides it to the voltage value calculation unit 245.

The charge/discharge current value input unit 243 accepts input of charge/discharge current values from the computer 100 via the LAN and provides the values to the capacity value calculation unit 244.

At the start of the simulation, the capacity value calculation unit 244 determines the remaining capacity of the first battery cell based on the charge/discharge current value provided by the charge/discharge current value input unit 243. For example, if the charge/discharge current value indicates charging, the remaining capacity of the first battery cell is determined to be empty, and if the charge/discharge current value indicates discharging, the remaining capacity of the first battery cell is determined to be fully charged. During the simulation, the capacity value calculation unit 244 calculates the increase/decrease in the remaining capacity of the battery cell based on the load current value, which is the value of the current output from the battery cell, and the elapsed time. The load current is determined based on the charge/discharge current value provided by the charge/discharge current value input unit 243 and the current at the connection terminal 225 measured by the current measurement unit 223.

The capacity value calculation unit 244 calculates the current integrated value, which is the integrated value of the load current, by multiplying the load current value, which is the value of the current output from the battery cell, by the elapsed time. When simulating charging, the remaining capacity of the initial battery cell is empty, so this integrated value becomes the remaining capacity. When simulating discharging, the remaining capacity can be calculated by subtracting this current integrated value from the capacity when fully charged.

In the capacity value calculation unit 244 of the voltage generation system 1 of this embodiment, the calculation of the remaining capacity of the battery cell can be performed every time equivalent to one period of the power supply frequency (1 PLC: Power Line Cycle), but is not limited to this. If the capacity value calculation unit 244 performs calculations at 1 PLC intervals, for example, with a 50 Hz power supply, 1 PLC is 20 ms, so the remaining capacity of the battery cell can be calculated with an elapsed time of 20 ms.

The voltage value calculation unit 245 calculates the terminal-to-terminal voltage value of the battery cell corresponding to the remaining capacity of the battery cell provided by the capacity value calculation unit 244 based on the relational equation provided by the relational equation acquisition unit 241, and provides the calculated voltage value to the voltage generation unit 222 of the cell voltage generation unit 220.

Next, the operation of the voltage generation system 1 of the second embodiment will be described.

Figure 9 is a sequence diagram showing the processing flow between the computer 100 and the voltage generating device 200 in the voltage generating system 1.

First, in the computer 100, the measurement value pair input unit 110 accepts input of a measurement value pair from the user (step S301). Specifically, the processing unit 102 performs processing to accept the input via the input/output unit 103. The measurement value pair is input by the user having previously measured the measurement value pair using a charge/discharge tester.

When the input of the measurement value pair is accepted, the relational equation generation unit 120 generates a relational equation (step S302). The relational equation is calculated by, for example, using the least squares method, a singular point decomposition algorithm, or the like to calculate a polynomial that approximates the input measurement value pair. The calculated polynomial is judged to be appropriate depending on whether the residual with the actual measurement value is less than a predetermined value, and if it is inappropriate, it is calculated again using a different approximation method.

In the computer 100, the processing unit 102 receives input of the charge/discharge current value from the user via the input/output unit 103 (step S303). The processing unit 102 provides the received charge/discharge current value to the charge/discharge current value input unit 243 of the voltage generating device 200.

When the processing unit 102 receives an input of an execution instruction to generate a voltage (step S304), it outputs the instruction to that effect to the voltage generating device 200.

In response to the execution instruction of step S304, the voltage generating device 200 executes a voltage generation process based on the measurement value pairs and the charge/discharge current values received from the computer 100 (step S400). The flow of the voltage generation process will be described in detail below.

Figure 10 is a flow diagram showing the detailed process flow of the voltage generation process. (Simulation starts)

In the voltage generating device 200, the capacity value calculation unit 244 first starts the voltage generation process and determines whether a charging or discharging simulation is to be performed based on the charging and discharging current value input by the charging and discharging current value input unit 243 (step S401). Note that in step S401, it is only determined whether the initial state is charging or discharging based on the input charging and discharging current value. After starting the simulation, it may determine whether the current state is charging or discharging according to fluctuations in the cell balancing current, etc., which will be described later, and perform a simulation that is the opposite of the charging or discharging that was initially determined.

If it is determined in step S401 that charging is occurring, the remaining capacity used first is set to the minimum capacity (empty) of the measured value plot (step S403). On the other hand, if it is determined in step S401 that discharging is occurring, the remaining capacity used first is set to the maximum capacity (fully charged) of the measured value plot (step S402).

Next, the current measurement unit 223 performs a current measurement and provides the measured current value (cell balancing current value) to the capacity value calculation unit 244 (step S404).

The capacity value calculation unit 244 calculates the load current value Io, which is the sum of the charge/discharge current value IL and the cell balancing current value IB (step S405), and determines whether the current simulation is charging or discharging (step S406). For example, if a load current value Io is calculated that causes the current flowing out of the battery cell to be positive, it can be determined that the current simulation is discharging. On the other hand, if a load current value Io is calculated that causes the current flowing out of the battery cell to be negative, it can be determined that the current simulation is charging.

In step S406, if the capacity value calculation unit 244 determines that discharging is occurring, it multiplies the load current value Io by the elapsed time to determine the current capacity flowing through the battery, and subtracts this from the remaining capacity to calculate the current remaining capacity (step S407). Furthermore, the capacity value calculation unit 244 determines whether the current remaining capacity has reached the minimum current capacity (step S408). If it is determined in step S408 that the current remaining capacity has reached the minimum current capacity, the voltage generation process is terminated.

In step S406, if the capacity value calculation unit 244 determines that charging is to be performed, it multiplies the load current value Io by the elapsed time to determine the current capacity flowing through the battery, and adds this to the remaining capacity to calculate the value of the current remaining capacity (step S409). Furthermore, the capacity value calculation unit 244 determines whether the current remaining capacity has reached the maximum current capacity (step S410). If it is determined in step S410 that the current remaining capacity has reached the maximum current capacity, the voltage generation process is terminated.

If it is not determined in steps S408 and S410 that the voltage generation process has ended, the capacity value calculation unit 244 provides the calculated remaining capacity value to the voltage value calculation unit 245, and the voltage value calculation unit 245 substitutes the received remaining capacity into the relational equation to calculate the voltage value (step S411).

The voltage value calculation unit 245 determines whether the currently calculated output voltage is equal to the previously calculated voltage value (step S412). If the voltage value calculation unit 245 determines that they are not equal (step S412: No), it further determines whether the calculated voltage value is smaller than the minimum voltage value or larger than the maximum voltage value (step S413). If the calculated voltage value is smaller than the minimum voltage value or larger than the maximum voltage value, the voltage value calculation unit 245 ends the voltage generation process.

If the calculated voltage value is greater than the minimum voltage value and not greater than the maximum voltage value, the voltage value calculation unit 245 changes the voltage value to be provided to the voltage generation unit 222 to the calculated voltage value (step S414), and returns to the current measurement in step S404 to calculate the remaining capacity.

As described above, the voltage generating device 200 according to this embodiment makes it possible to generate a voltage that simulates the voltage behavior of the battery cell when the load on the battery changes.

(Modification of the embodiment)
Although the voltage generating system 1 according to the embodiment has been described above by taking a specific example, the present invention is not limited thereto, and various modifications can be adopted.

For example, in the above embodiment, a case has been described in which the relational equation between the remaining capacity of a battery cell and the terminal voltage value is not particularly different between charging and discharging. However, as shown in FIG. 11, the relational equation generation unit 215 of the relational equation acquisition unit 213 may generate different relational equations for charging and discharging. In this case, the voltage value calculation unit 219 can determine the terminal voltage using the relational equation generated based on different measurement value pairs for charging and discharging as the relational equation to be used for calculation.

In the above embodiment, the cell balancing current has been described as being generated by active cell balancing operation, but the present invention is not limited to this. The cell balancing current may be generated by passive cell balancing operation.

In the above embodiment, the measurement value pair is a combination of the remaining capacity of a battery cell and the terminal voltage value of the battery cell at that remaining capacity, but this is not limited to the above. Instead of the remaining capacity of the battery cell, the measurement value pair may be a combination using an integrated current value. In this case, if the discharge (charge) current at the start of discharge (charge) is x [A] and flows for t [sec], the integrated current value is xt/3600 [Ah], and the terminal voltage value of the battery cell at that time can be obtained as the measurement value pair.

1: Voltage generation system, 100: Computer (PC), 101: Display unit, 102: Processing unit, 103: Input/output unit, 110: Measurement value pair input unit, 120: Relational equation generation unit, 200: Voltage generation device, 210: Data processing control unit, 211, 212: MCU, 213: Relational equation acquisition unit, 214: Measurement value pair input unit, 215: Relational equation generation unit, 217, 243: Charging/discharging Current value input section, 218, 244...capacity value calculation section, 219, 245...voltage value calculation section, 220_1 to 220_n (220)...cell voltage generation section, 222_1 to 222_n (222)...voltage generation section, 223_1 to 223_n (223)...current measurement section, 224_1 to 224_n (224)...voltage measurement section, 225_1 to 225_n (225)...connection terminal, 226, output section, 300...BMS

Claims (8)

a relational equation acquisition unit that acquires a relational equation indicating a relationship between a remaining capacity of a battery cell and a terminal voltage value of the battery cell at the remaining capacity, the relational equation being generated based on a measurement value pair that is a set of a remaining capacity of the battery cell and a measurement value of the terminal voltage value of the battery cell at the remaining capacity;
a capacity value calculation unit that calculates the remaining capacity based on a load current value, which is a value of a current output from the battery cell, and an elapsed time;
a voltage value calculation unit that calculates the inter-terminal voltage value corresponding to the input remaining capacity of the battery cell based on the relational expression;
a voltage generating unit that generates a voltage according to the inter-terminal voltage value calculated by the voltage value calculating unit;
Equipped with
the voltage value calculation unit calculates a terminal-to-terminal voltage value corresponding to the remaining capacity calculated by the capacity value calculation unit;
The load current value is a sum of a charge/discharge current value flowing through a load connected to the battery cell and a cell balancing current value which is a current input/output for equalizing the inter-terminal voltage value between the battery cell and another battery cell.
Voltage generator. 2. The voltage generating device according to claim 1 ,
an external terminal connected to an external device and configured to output the voltage generated by the voltage generating unit to the external device; and a current measuring unit configured to measure a current flowing through the external terminal,
The capacitance value calculation unit sets the current value measured by the current measurement unit as the cell balancing current value.
Voltage generator. 3. The voltage generating device according to claim 1 ,
The relational equation acquired by the relational equation acquisition unit is an equation based on a function obtained by linearly interpolating between the two measurement value pairs.
Voltage generator. 4. The voltage generating device according to claim 1,
the relational expression acquired by the relational expression acquisition unit is a polynomial.
Voltage generator. 4. The voltage generating device according to claim 3 ,
The relational equation acquisition unit includes an input unit that accepts an input of the measurement value pairs, and a relational equation generation unit that generates the relational equation based on the input measurement value pairs.
Voltage generator. A voltage generating system comprising the voltage generating device according to claim 4 and a computer,
The computer includes an input unit that receives an input of the measurement value pairs, and a relational equation generation unit that generates the relational equation based on the input measurement value pairs,
The relational expression acquisition unit acquires the relational expression generated by the computer.
Voltage generation system. a relational expression acquisition function for acquiring a relational expression indicating a relationship between a remaining capacity of a battery cell and a terminal voltage value of the battery cell at the remaining capacity, the relational expression being generated based on a measurement value pair formed of a remaining capacity of the battery cell and a measurement value of the terminal voltage value of the battery cell at the remaining capacity;
a capacity value calculation function that calculates a remaining capacity of the battery cell based on a load current value, which is a value of a current output from the battery cell, and an elapsed time;
a voltage value calculation function for calculating the inter-terminal voltage value corresponding to the input remaining capacity of the battery cell based on the relational expression;
a voltage generating function of generating a voltage according to the inter-terminal voltage value calculated by the voltage value calculating function,
the voltage value calculation function calculates a terminal-to-terminal voltage value corresponding to the remaining capacity calculated by the capacity value calculation function;
The load current value is a sum of a charge/discharge current value flowing through a load connected to the battery cell and a cell balancing current value which is a current input/output for equalizing the inter-terminal voltage value between the battery cell and another battery cell.
Voltage generation program. a relational equation acquisition step of acquiring a relational equation indicating a relationship between a remaining capacity of a battery cell and a terminal voltage value of the battery cell at the remaining capacity, the relational equation being generated based on a measurement value pair formed of a remaining capacity of the battery cell and a measurement value of the terminal voltage value of the battery cell at the remaining capacity;
a capacity value calculation step of calculating a remaining capacity of the battery cell based on a load current value, which is a value of a current output from the battery cell, and an elapsed time;
a voltage value calculation step of calculating the inter-terminal voltage value corresponding to the input remaining capacity of the battery cell based on the relational expression;
a voltage generating step of generating a voltage according to the inter-terminal voltage value calculated in the voltage value calculating step;
Including ,
the voltage value calculation step calculates a terminal-to-terminal voltage value corresponding to the remaining capacity calculated in the capacity value calculation step;
The load current value is a sum of a charge/discharge current value flowing through a load connected to the battery cell and a cell balancing current value which is a current input/output for equalizing the inter-terminal voltage value between the battery cell and another battery cell.
Voltage generation method.

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