Patent Description:
Changes in current-voltage behavior waveform of a rechargeable battery are discussed by defining the internal resistance of the rechargeable battery as an equivalent circuit constructed by connecting parallel circuits of resistor R and capacitor C in multiple stages. However, in order to explain the transient response waveform of the voltage for a few or more seconds, a capacitor capacitance value of several <NUM> F to several <NUM> F would have to be used as the time constant element. Such values are not compatible with the AC impedance and its equivalent circuit model used for evaluating the AC characteristics of a battery, and cannot be said to reproduce the battery properties.

The internal resistance is one of the characteristic items of a rechargeable battery. For example, in a lithium-ion rechargeable battery, complicated chemical reactions such as electrode reactions, SEI reactions, ion diffusion reactions, etc. inside the battery occur in an intertwined manner, and the behavior of the battery voltage is not of the kind where Ohm's law can be applied by regarding the internal resistance as a mere DC resistance.

Conventionally, as a method for evaluating the internal resistance of a battery, an AC impedance analysis method based on frequency response analysis (FRA) is well known. A method has been established to interpret various internal reactions by decomposing them into a number of time constant elements by applying an equivalent circuit model. The behavior of a battery on the order of seconds is dominated by the diffusion phenomenon as Warburg resistance, and how well this Warburg resistance is incorporated into an operating model determines the performance as the model. In order to measure the AC impedance, a dedicated device such as a frequency response analyzer (FRA) is required.

However, in practical use, the rechargeable battery is connected to a load and is repeatedly charged and discharged. In that case, only voltage, current, and temperature are measured as basic information to know the state of the rechargeable battery. Under these circumstances, the output voltage of the battery is affected by the internal resistance, and the internal resistance itself varies depending on the temperature conditions or the degree of degradation of the battery. There has been a need for a means that can reproduce with accuracy the characteristics of a battery in its actual operating state.

In view of the foregoing, it is an object of the present invention to provide a device or the like that can improve the accuracy in reproduction of the characteristics of a rechargeable battery by a simulation battery under various conditions.

A simulation battery construction device according to the present invention includes:.

A corresponding simulation battery construction method according to claim <NUM> is provided.

In the simulation battery construction device of the present invention, it is preferable that.

In the simulation battery construction device of the present invention, it is preferable that
the first recognition element recognizes a first measured output voltage and a second measured output voltage as measurement results of the manner of change of a voltage output from the rechargeable battery in response to an impulse current input to the rechargeable battery at a first designated time point and a second designated time point, respectively, the second designated time point being a time point of measurement of the complex impedance of the rechargeable battery that is later than the first designated time point, and recognizes the degradation state of the rechargeable battery at the second designated time point with respect to the rechargeable battery at the first designated time point based on a contrast between the first and second measured output voltages.

In the simulation battery construction device of the present invention, it is preferable that
the first recognition element, based on a mutual communication with a designated apparatus having the rechargeable battery mounted thereon as a power supply, recognizes a voltage response characteristic of the rechargeable battery measured by a sensor mounted on the designated apparatus as each of the first and second measured output voltages as the measurement results of the manner of change of the voltage output from the rechargeable battery in the case where the impulse current generated by a pulse current generator mounted on the designated apparatus is input to the rechargeable battery.

In the simulation battery construction device of the present invention, it is preferable that
the first recognition element, based on a mutual communication with a designated apparatus having the rechargeable battery mounted thereon as a power supply, recognizes the complex impedance of the rechargeable battery measured in accordance with an AC impedance method by a measuring instrument mounted on the designated apparatus.

The simulation battery construction device <NUM> as an embodiment of the present invention shown in <FIG> is composed of one or more servers that can communicate with each of a database <NUM>, a simulation battery <NUM>, and a designated apparatus <NUM> via a network. The simulation battery construction device <NUM> controls a voltage applied from the simulation battery <NUM> to the designated apparatus <NUM>. The database <NUM> may be a constituent element of the simulation battery construction device <NUM>.

The simulation battery construction device <NUM> includes a first recognition element <NUM>, a second recognition element <NUM>, a first calculation element <NUM>, a second calculation element <NUM>, and a simulation battery control element <NUM>. The first recognition element <NUM>, the second recognition element <NUM>, the first calculation element <NUM>, the second calculation element <NUM>, and the simulation battery control element <NUM> are each composed of a processor (arithmetic processing unit), a memory (storage device), an I/O circuit, and others.

The memory or a separate storage device stores and retains various data such as measurement results of voltage response characteristics of a rechargeable battery <NUM> with respect to an impulse current, as well as programs (software). For example, a plurality of identifiers each identifying the type (as specified by standards and specifications) of a rechargeable battery <NUM> or a designated apparatus <NUM> having the rechargeable battery <NUM> mounted thereon and a plurality of rechargeable battery models are associated respectively, and stored and retained in the memory. The processor reads the necessary program and data from the memory and executes arithmetic processing in accordance with the program based on the data, thereby executing the arithmetic processing or tasks (described below) assigned to the respective elements <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> constituting the simulation battery construction device <NUM>.

As shown in <FIG>, the simulation battery <NUM> includes a D/A converter <NUM> and an amplifier <NUM>. The D/A converter <NUM>, when receiving a voltage command value Vcmd(t) output from a rechargeable battery model, D/A converts the received value. The amplifier <NUM> applies a voltage V(t) according to the output from the D/A converter <NUM> to the designated apparatus <NUM> or a load constituting the apparatus <NUM>. Here, "(t)" means a value or a time series at time t.

The calculator (second calculation element <NUM>) corresponding to the rechargeable battery model includes a calculator <NUM>, an output unit <NUM>, and an adder <NUM>. The calculator <NUM>, when receiving a current command value Icmd(t), computes an output voltage derived from a virtual internal resistance of the simulation battery <NUM>. The current command value Icmd(t) may be provided from the designated apparatus <NUM>. The values of parameters defining a transfer function H of the calculator <NUM> are adjusted by a model parameter adjustment element <NUM> based on a degradation degree D(m2) of a virtual rechargeable battery simulated by the simulation battery <NUM>. The output unit <NUM> outputs a virtual open-circuit voltage OCV(t) of the simulation battery <NUM>. The adder <NUM> adds up the outputs of the calculator <NUM> and the output unit <NUM>.

The simulation battery <NUM> may be configured with an external power supply such as a commercial power supply to which the designated apparatus <NUM> is connected. The simulation battery <NUM> may be mounted on the designated apparatus <NUM> in place of the rechargeable battery <NUM>. The simulation battery <NUM> may include the second calculation element <NUM>. In this case, the second calculation element <NUM> may be configured with a control device <NUM> constituting the designated apparatus <NUM>.

The designated apparatus <NUM> includes an input interface <NUM>, an output interface <NUM>, the control device <NUM>, the rechargeable battery <NUM>, and a sensor group <NUM>. The designated apparatus <NUM> includes any apparatus that uses the rechargeable battery <NUM> as a power supply, such as a personal computer, cellular phone (smartphone), home appliance, or mobile body such as an electric bicycle.

The control device <NUM> is composed of a processor (arithmetic processing unit), a memory (storage device), an I/O circuit, and others. The memory or a separate storage device stores and retains various data such as the measurement results of the voltage response characteristics of the rechargeable battery <NUM>. The control device <NUM> operates in response to the power supplied from the rechargeable battery <NUM> and controls the operation of the designated apparatus <NUM> in the energized state. The operation of the designated apparatus <NUM> includes the operation of an actuator (such as an electric actuator) that constitutes the designated apparatus <NUM>. The processor constituting the control device <NUM> reads the necessary program and data from the memory, and executes the arithmetic processing assigned in accordance with the program based on the data.

The rechargeable battery <NUM> is, for example, a lithium-ion battery, and may be any other rechargeable battery such as a nickel-cadmium battery. In the case where power is supplied from the simulation battery <NUM> to the designated apparatus <NUM>, the rechargeable battery <NUM> may be removed from the designated apparatus <NUM>. The sensor group <NUM> measures the voltage response characteristics and temperature of the rechargeable battery <NUM>, as well as the values of parameters necessary for controlling the designated apparatus <NUM>. The sensor group <NUM> includes, for example, a voltage sensor, a current sensor, and a temperature sensor that output signals corresponding respectively to the voltage, current, and temperature of the rechargeable battery <NUM>.

The simulation battery construction device <NUM> may be installed in the designated apparatus <NUM>. In this case, a software server (not shown) may transmit degradation determining software to the arithmetic processing unit constituting the control device <NUM> included in the designated apparatus <NUM>, thereby imparting the functions as the simulation battery construction device <NUM> to the arithmetic processing unit.

A description will now be made of a simulation battery construction method which is performed by the simulation battery construction device <NUM> of the above configuration.

Parameters P(n0,n1,n2) of a rechargeable battery model at each of different temperatures T(n1) at each of different degradation degrees D(n2) are determined for various types of rechargeable batteries <NUM> having their types identified by the identifier id(n0).

Specifically, firstly, in the simulation battery construction device <NUM>, a first index n1 and a second index n2 are each set to "<NUM>" (STEP <NUM> in <FIG>). The first index n1 is an index that represents the high or low of temperature T of the rechargeable battery <NUM>. The second index n2 is an index that represents the number of times of the evaluation made, or the order of the evaluation period, of the degradation degree D of the rechargeable battery <NUM>.

The temperature T of the rechargeable battery <NUM> is controlled to a temperature T(n1) (STEP <NUM> in <FIG>). For the temperature adjustment of the rechargeable battery <NUM>, a heater (such as an electric heater) and a cooler (such as a cooling fan) placed near the rechargeable battery <NUM>, as well as a temperature sensor placed near the rechargeable battery <NUM> or attached to the housing of the rechargeable battery <NUM> are used.

The first recognition element <NUM> recognizes a measurement result of a complex impedance Z(n0,n1,n2) of the rechargeable battery <NUM> (STEP <NUM> in <FIG>). For each element to "recognize" information means to perform any arithmetic processing, etc. for preparing necessary information, which includes to receive information, to retrieve or read information from the database <NUM> or other information source, and to calculate or estimate information based on other information. The complex impedance Z(n0,n1,n2) of the rechargeable battery <NUM> is measured with the AC impedance method, and the measurement result is registered in the database <NUM> in association with an identifier for identifying the type of the rechargeable battery <NUM>.

According to the AC impedance method, a combination of a frequency response analyzer (FRA) <NUM> and a potentio-galvanostat (PGS) <NUM> is used, as shown in <FIG>. An oscillator constituting the FRA <NUM> outputs a sinusoidal signal of an arbitrary frequency, and a current signal I(t) and a voltage signal V(t) of the rechargeable battery <NUM> according to the sinusoidal signal are input from the PGS <NUM> to the FRA <NUM>. In the FRA <NUM>, the current signal I(t) and the voltage signal V(t) are converted into frequency domain data by means of discrete Fourier frequency transform, and the complex impedance Z(n0,n1,n2)(ω) at the frequency f = (ω/2π) is measured.

For example, the complex impedance Z(n0,n1,n2) of the rechargeable battery <NUM> in the state of not being mounted on the designated apparatus <NUM>, such as immediately before shipment of the rechargeable battery <NUM>, is measured. Alternatively, the complex impedance Z(n0,n1,n2) of the rechargeable battery <NUM> in the state of being mounted on the designated apparatus <NUM> may be measured. In this case, the FRA <NUM> may be configured with the control device <NUM>, and the sensor group <NUM> may be configured with the PGS <NUM>. For example, the designated apparatus <NUM> may be connected to an external power supply such as a commercial power supply for the purpose of charging the rechargeable battery <NUM>, and a sinusoidal signal may be output with the power supplied from the external power supply.

<FIG> shows an example of a Nyquist plot representing the actual measurement results of the complex impedance Z(n0,n1,n2) of the rechargeable battery <NUM>, together with an approximate curve of the plot. The horizontal axis represents real part ReZ of the complex impedance Z, and the vertical axis represents imaginary part -ImZ of the complex impedance Z. The larger ReZ in the region of -ImZ><NUM> represents the complex impedance Z at lower frequencies. The value of ReZ when -ImZ=<NUM> corresponds to the transfer resistance in the electrolytic solution of the rechargeable battery <NUM>. The radius of curvature of the approximately semicircular portion in the region of -ImZ><NUM> corresponds to the charge transfer resistance of the rechargeable battery <NUM>. The radius of curvature tends to become smaller as the temperature T of the rechargeable battery <NUM> becomes higher. The linear portion rising at about <NUM>° in the low frequency region of the region of -ImZ><NUM> reflects the effect of the Warburg impedance of the rechargeable battery <NUM>.

In the simulation battery construction device <NUM>, values of parameters P(n0,n1,n2) of a rechargeable battery model are identified by the first calculation element <NUM> based on the measurement result of the complex impedance Z of the rechargeable battery <NUM> recognized by the first recognition element <NUM> (STEP <NUM> in <FIG>). The parameters P(n0,n1,n2) define the transfer function H of the calculator <NUM>.

The rechargeable battery model is a model that expresses a voltage V(t) output from a rechargeable battery <NUM> when a current I(t) is input to the rechargeable battery <NUM>. It is defined using an open-circuit voltage OCV and a transfer function H(t) of the internal resistance of the rechargeable battery <NUM> by the relational expression (<NUM>).

Here, OCV(t) indicates that the open-circuit voltage increases or decreases as the current I(t) is charged and/or discharged.

A transfer function H(z) of an equivalent circuit model of the internal resistance of a rechargeable battery is defined by the following relational expression (<NUM>).

Here, "H<NUM>(z)", "Hi(z)", "HW(z)", and "HL(z)" are defined by parameters that represent the characteristics of the internal resistance of the rechargeable battery.

<FIG> shows an example of an equivalent circuit of the internal resistance of the rechargeable battery <NUM>. In this example, the equivalent circuit of the internal resistance is defined by a series circuit of: a resistor R<NUM>, corresponding to the transfer resistance in the electrolytic solution; the i-th RC parallel circuit (i = <NUM>, <NUM>,. , X) consisting of a resistor Ri and a capacitor Ci, corresponding to the charge transfer resistance; a resistor W<NUM>, corresponding to the Warburg impedance; and a coil L. Although the number of series-connected RC parallel circuits is "<NUM>" in the example shown in <FIG>, it can be smaller or larger than <NUM>. The resistor W<NUM> may be connected in series with the resistor R in at least one RC parallel circuit. The capacitor C may be replaced by a constant phase element (CPE). As shown in <FIG>, the Warburg resistor, W<NUM>, may be connected in series with the resistor R in at least one RC parallel circuit (the first RC parallel circuit in the example of <FIG>).

The transfer function H<NUM>(z) of the resistor R<NUM> is defined by the relational expression (<NUM>).

The transfer function Hi(z) of the i-th RC parallel circuit is defined as a transfer function of an infinite impulse response (IIR) system by the relational expression (<NUM>). <FIG> shows a block diagram representing the transfer function Hi(z) of the i-th RC parallel circuit.

The transfer function HW(z) of the resistor W<NUM> corresponding to the Warburg impedance is defined as a transfer function of a finite impulse response (FIR) system by the relational expression (<NUM>). <FIG> shows a block diagram representing the transfer function HW(z) of the resistor W<NUM> corresponding to the Warburg impedance.

The transfer function HL(z) of the coil L is defined by the relational expression (<NUM>).

An approximate curve of the complex impedance Z of the rechargeable battery represented by the Nyquist plot, shown with a solid line in <FIG>, is obtained under the assumption that the transfer function H(z) of the equivalent circuit model of the internal resistance of the rechargeable battery is defined according to the relational expression (<NUM>). This allows the values of the parameters P(n0,n1,n2) = {R<NUM>, ai, b<NUM>, bi, hk, L<NUM>, T} to be obtained (see the relational expressions (<NUM>) to (<NUM>)). The value of the open-circuit voltage OCV(t) output from the output unit <NUM> in the rechargeable battery model is identified by the measurement value of the open-circuit voltage OCV(n0,n1,n2) (see the relational expression (<NUM>)). Then, depending on the values of the parameters, the rechargeable battery models are established for various types of rechargeable batteries <NUM>.

It is determined whether the first index n1 is a predetermined number N1 or larger (STEP <NUM> in <FIG>). If the determination result is negative (NO in STEP <NUM> in <FIG>), the value of the first index n1 is increased by "<NUM>" (STEP <NUM> in <FIG>). Then, the process of temperature adjustment of the rechargeable battery <NUM> and on are repeated (STEPS <NUM>→<NUM>→<NUM>→<NUM> in <FIG>).

If the determination result is positive (YES in STEP <NUM> in <FIG>), the second recognition element <NUM> recognizes the measurement result of the voltage response characteristic V(n0,n2)(t) (- V(n0,n2)(z)) according to the impulse current I(t) of the rechargeable battery <NUM> (STEP <NUM> in <FIG>).

During the measurement, the impulse current I(t) (- I(z)) is input to the rechargeable battery <NUM>. For example, the impulse current I(t) as shown in <FIG> is input to the rechargeable battery <NUM>. When a pulse current generator is driven, the impulse current I(t) generated in the pulse current generator is input to the rechargeable battery <NUM>. In the case where the rechargeable battery <NUM> is mounted on the designated apparatus <NUM>, the pulse current generator may be mounted on the designated apparatus <NUM>. The pulse current generator mounted on the designated apparatus <NUM> may be driven by power that is supplied from an external power supply or an auxiliary power supply mounted on the designated apparatus <NUM>.

Then, on the basis of the output signal of the voltage sensor, the control device <NUM> measures the voltage response characteristic V(n0,n2)(t) of the rechargeable battery <NUM>. In the case where the rechargeable battery <NUM> is mounted on the designated apparatus <NUM>, the voltage response characteristic V(n0,n2)(t) of the rechargeable battery <NUM> may be measured by the control device <NUM> on the basis of the output signal of the voltage sensor constituting the sensor group <NUM> mounted on the designated apparatus <NUM>. In this manner, the voltage response characteristic V(n0,n2)(t) of the rechargeable battery <NUM>, which varies as shown by the broken line in <FIG>, for example, is measured. In <FIG>, the measurement result of the voltage response characteristic V(n0,<NUM>)(t) of the rechargeable battery <NUM> when the second index n2 is <NUM> is shown by the solid line.

Subsequently, the second calculation element <NUM> evaluates the degradation degree D(n0,n2) of the rechargeable battery <NUM> having its type identified by the identifier id(n0), on the basis of the result of contrast between the voltage response characteristics V(n0,n2)(t) and V(n0,<NUM>)(t) of the rechargeable battery <NUM> (STEP <NUM> in <FIG>). For example, the similarity x between the curves representing the voltage response characteristics V(n0,n2)(t) and V(n0,<NUM>)(t), respectively, of the rechargeable battery <NUM> is calculated. Then, the degradation degree D(n0,n2) = f(x) of the rechargeable battery <NUM> is calculated in accordance with a decreasing function f with the similarity x as the main variable.

It is determined whether the second index n2 is a predetermined number N2 or larger (STEP <NUM> in <FIG>) If the determination result is negative (NO in STEP <NUM> in <FIG>), the value of the first index n1 is reset to "<NUM>" and the value of the second index n2 is increased by "<NUM>" (STEP <NUM> in <FIG>). Then, the process of temperature adjustment of the rechargeable battery <NUM> and on are repeated (STEPS <NUM>→<NUM>→<NUM>→<NUM> in <FIG>).

The second recognition element <NUM> recognizes an identifier id(m0) that identifies the type of a virtual rechargeable battery to be simulated by the simulation battery <NUM> (STEP <NUM> in <FIG>). For example, the second recognition element <NUM> may recognize, on the basis of a communication with the designated apparatus <NUM>, the identifier id(m0) that identifies the type of the rechargeable battery that is planned to be applied to the designated apparatus <NUM>. Alternatively, the identifier id(m0) may be recognized by the second recognition element <NUM>, on the basis of the communication with the designated apparatus <NUM>, in accordance with the virtual rechargeable battery type that has been set through the input interface <NUM> of the designated apparatus <NUM>.

The second recognition element <NUM> recognizes the temperature T(m1) of the virtual rechargeable battery simulated by the simulation battery <NUM> (STEP <NUM> in <FIG>). For example, the second recognition element <NUM> may recognize, on the basis of the communication with the designated apparatus <NUM>, the temperature of the designated apparatus <NUM> measured by a temperature sensor constituting the sensor group <NUM> of the designated apparatus <NUM> as the temperature T(m1) of the virtual rechargeable battery. Alternatively, the second recognition element <NUM> may recognize, on the basis of the communication with the designated apparatus <NUM>, a temperature that has been set through the input interface <NUM> of the designated apparatus <NUM> as the temperature T(m1) of the virtual rechargeable battery.

The second recognition element <NUM> recognizes the degradation degree D(m2) of the virtual rechargeable battery simulated by the simulation battery <NUM> (STEP <NUM> in <FIG>). For example, the second recognition element <NUM> may recognize, on the basis of the communication with the designated apparatus <NUM>, the degradation degree that has been set through the input interface <NUM> of the designated apparatus <NUM> as the degradation degree D(m2) of the virtual rechargeable battery.

The second calculation element <NUM> selects, from among a large number of rechargeable battery models registered in the database <NUM>, one rechargeable battery model that is specified by the parameters P(m0, m1, m2) on the basis of the recognition results by the second recognition element <NUM> of the identifier id(m0) identifying the type, the temperature T(m1), and the degradation degree D(m2) of the virtual rechargeable battery simulated by the simulation battery <NUM> (STEP <NUM> in <FIG>). This corresponds to the event that the values of the parameters P(n0,n1,n2), which define the transfer function H of the calculator <NUM> shown in <FIG>, are adjusted by the model parameter adjustment element <NUM> on the basis of the degradation degree D(m2) of the virtual rechargeable battery simulated by the simulation battery <NUM>.

In addition, the second recognition element <NUM> recognizes a current command value Icmd(t) (STEP <NUM> in <FIG>). For example, the second recognition element <NUM> may recognize, on the basis of the communication with the designated apparatus <NUM>, a desired current value for the load that is set by the control device <NUM> according to the operating status of the designated apparatus <NUM> measured by the sensor group <NUM> of the designated apparatus <NUM>, as the current command value Icmd(t). Alternatively, the second recognition element <NUM> may recognize, on the basis of the communication with the designated apparatus <NUM>, a desired current value that has been set through the input interface <NUM> of the designated apparatus <NUM>, as the current command value Icmd(t). With this, the current command value Icmd(t) that varies with time as shown by the solid line in <FIG>, for example, is recognized.

The second calculation element <NUM> inputs the current command value Icmd(t) to the selected rechargeable battery model, and calculates a voltage command value Vcmd(t) as the output of the rechargeable battery model (STEP <NUM> in <FIG>). With this, the voltage command value Vcmd (t) that varies as shown by the thin line in <FIG>, for example, is calculated as the output of the rechargeable battery model.

Subsequently, the simulation battery control element <NUM> performs control such that a voltage V(t) obtained by multiplying the voltage command value Vcmd(t) by a gain by the amplifier <NUM> in the simulation battery <NUM> is applied to the designated apparatus <NUM> or a designated load constituting the designated apparatus <NUM> (STEP <NUM> in <FIG>). In this manner, the voltage V(t) that varies as shown by the bold line in <FIG>, for example, is applied to the designated apparatus <NUM>.

In the above embodiment, the values of the parameters P(n0,n1,n2) of the rechargeable battery models were individually determined according to the differences in the degradation degree D(n2) of the rechargeable batteries <NUM> having their types identified by the identifier id(n0) (see STEPS <NUM>, <NUM>, and <NUM> in <FIG>). As another embodiment, the values of the parameters P(n0,n1) of the rechargeable battery models may be determined without taking into account the differences in the degradation degree D(n2) of the rechargeable batteries <NUM>.

In the above embodiment, the values of the parameters P(n0,n1,n2) of the rechargeable battery models were individually determined according to the differences in the temperature T(n1) of the rechargeable batteries <NUM> having their types identified by the identifier id(n0) (see STEPS <NUM>, <NUM>, and <NUM> in <FIG>). As another embodiment, the values of the parameters P(n0,n2) of the rechargeable battery models may be determined without taking into account the differences in the temperature T(n1) of the rechargeable batteries <NUM>.

According to the simulation battery construction device <NUM> and the simulation battery construction method performed by the same according to the present invention, the parameters P(n0,n1,n2) of a rechargeable battery model at each of different temperatures T(n1) at each of different degradation degrees D(n2) are determined for a rechargeable battery <NUM> having its type identified by the identifier id(n0). On the basis of the measurement result of the complex impedance Z of the rechargeable battery <NUM>, the values of the parameters P(n0,n1,n2) of the rechargeable battery model are identified (see STEPS <NUM>→<NUM>→<NUM> in <FIG>; <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, and <FIG>). The rechargeable battery model expresses the impedance of the internal resistance of the rechargeable battery <NUM> with the transfer functions that represent the IIR and FIR systems, respectively (see the relational expressions (<NUM>) and (<NUM>); <FIG>, <FIG>, <FIG>, <FIG>, and <FIG>).

Further, on the basis of the identifier id(m0), temperature T(m1), and degradation degree D(m2) of the virtual rechargeable battery to be simulated by the simulation battery <NUM>, a rechargeable battery model having the parameters P(m0,m1,m2) is selected (see <FIG>; STEPS <NUM>→<NUM>→<NUM>→<NUM> in <FIG>). Then, the voltage command value Vcmd(t), which is the output when the current command value Icmd(t) is input to the rechargeable battery model, is calculated, and the voltage V(t) according thereto is applied to the designated apparatus <NUM> or its load by the simulation battery <NUM> (see <FIG>; STEPS <NUM>→<NUM>→<NUM> in <FIG>; <FIG>). This can improve the accuracy in reproduction of the characteristics of the rechargeable battery <NUM> by the simulation battery <NUM> under various conditions.

Claim 1:
A simulation battery construction device (<NUM>) comprising:
a first recognition element (<NUM>) configured to recognize a measurement result of a complex impedance of a rechargeable battery (<NUM>);
a first calculation element (<NUM>) configured to identify parameter values of a rechargeable battery model based on the measurement result of the complex impedance of the rechargeable battery recognized by the first recognition element (<NUM>), the rechargeable battery model expressing an impedance of an internal resistance of the rechargeable battery (<NUM>) with transfer functions representing an IIR system and an FIR system, respectively;
a second recognition element (<NUM>) configured to recognize a time series of a current command value;
a second calculation element (<NUM>) configured to calculate a time series of voltage simulating the rechargeable battery (<NUM>) as an output of the rechargeable battery model by inputting the time series of the current command value recognized by the second recognition element (<NUM>) to the rechargeable battery model; and
a simulation battery control element (<NUM>) configured to control an operation of a simulation battery (<NUM>) connected to a designated apparatus (<NUM>) so as to cause the time series of the voltage simulating the rechargeable battery (<NUM>) calculated by the second calculation element (<NUM>) to be applied to the designated apparatus (<NUM>).