WO2020049943A1 - Secondary battery temperature-raising device, computer program, and secondary battery temperature-raising method - Google Patents

Abstract

The secondary battery temperature-raising device is provided with: a setting unit for presetting charge/discharge parameters on the basis of parameters of a secondary battery necessary for setting the charge/discharge parameters of the secondary battery; and a control part for controlling the charging/discharging of the secondary battery on the basis of the charge/discharge parameters set by the setting unit.

Description

Secondary battery heating device, computer program, and secondary battery heating method

The present disclosure relates to a secondary battery heating device, a computer program, and a secondary battery heating method.
This application claims the priority based on Japanese Patent Application No. 2018-166179 filed on Sep. 5, 2018, and incorporates all the contents described in the Japanese application.

In recent years, vehicles such as HEV (Hybrid Electric Vehicle) and EV (Electric Vehicle) have become widespread. Vehicles such as HEV and EV are equipped with a plurality of secondary batteries for electric equipment and driving.

Patent Literature 1 discloses that a drive secondary battery is heated and discharged by charging and discharging a drive secondary battery and an electrical component secondary battery with each other to use the secondary battery in a more ideal state. A power supply device is disclosed.

JP 2003-92805 A

A secondary battery temperature raising device according to an embodiment of the present disclosure is a secondary battery temperature raising device that repeatedly charges and discharges a secondary battery to raise the temperature of the secondary battery, and that charges and discharges the secondary battery. A setting unit for setting the charging and discharging parameters in advance based on the parameters of the secondary battery necessary for setting the parameters; and charging and discharging of the secondary battery based on the charging and discharging parameters set by the setting unit. And a control unit for controlling the

A computer program according to an embodiment of the present disclosure is a computer program that causes a computer to execute processing for repeatedly charging and discharging a secondary battery to raise the temperature of the secondary battery. Based on the parameters of the secondary battery required to set the charge and discharge parameters of the battery, processing to set the charge and discharge parameters in advance, based on the set charge and discharge parameters, charge and discharge of the secondary battery Control processing is executed.

A method for raising the temperature of a secondary battery according to an embodiment of the present disclosure is a method for raising the temperature of a secondary battery by repeating charging and discharging of the secondary battery, wherein the charging and discharging of the secondary battery are performed. The charging / discharging parameters are set in advance based on the parameters of the secondary battery required for setting the parameters, and the charging / discharging of the secondary battery is controlled based on the set charging / discharging parameters.

FIG. 1 is a block diagram illustrating an example of a main configuration of a vehicle equipped with a controller according to an embodiment. 5 is a time chart showing an example of a current / voltage waveform of a main battery and a voltage waveform of a sub-battery at the time of charging and discharging. 4 is a time chart illustrating an example of an ON / OFF state of the FET. FIG. 4 is an explanatory diagram illustrating an example of an impedance spectrum of a main battery in a low frequency region. FIG. 4 is an explanatory diagram illustrating an example of an impedance spectrum of a resonance region of a main battery. FIG. 4 is an explanatory diagram illustrating an example of resonance frequency information in which a resonance frequency of a main battery is associated with a temperature. FIG. 4 is an explanatory diagram illustrating an example of a correlation between an open voltage of a main battery and a charging rate. FIG. 4 is a schematic diagram illustrating an example of a relationship between a charging current of a main battery and a duty ratio on a step-down side. FIG. 4 is a schematic diagram illustrating an example of a relationship between a discharge current of a main battery and a duty ratio on a boosting side. It is a schematic diagram which shows an example of the voltage waveform of a sub battery. It is a schematic diagram which shows an example of the voltage waveform of a sub battery. It is a schematic diagram which shows an example of the voltage waveform of a sub battery. FIG. 4 is an explanatory diagram illustrating an example of a method of adjusting a charging period and a discharging period in a charging / discharging cycle of a main battery. It is a flowchart which shows an example of the processing procedure of a controller.

[Problems to be solved by the present disclosure]
In the power supply device of Patent Literature 1, a current flowing in a secondary battery is detected, and the detected current is feedback-controlled to control a temperature rise of the secondary battery. However, since there is a delay in processing for performing feedback control, there is a limit to speeding up, and there is a possibility that the rate of temperature rise of the secondary battery cannot be increased.

Therefore, an object of the present invention is to provide a secondary battery temperature raising device, a computer program, and a secondary battery temperature raising method capable of improving a temperature rising rate of a secondary battery.
[Effects of the present disclosure]

According to the present disclosure, the rate of temperature rise of the secondary battery can be improved.

[Description of Embodiment of the Present Disclosure]
The secondary battery temperature raising device according to the present embodiment is a secondary battery temperature raising device that repeatedly charges and discharges the secondary battery and raises the temperature of the secondary battery. A setting unit for setting the charge / discharge parameter in advance based on the parameters of the secondary battery required for setting, and controlling the charge / discharge of the secondary battery based on the charge / discharge parameter set in the setting unit And a controller that performs the control.

The computer program according to the present embodiment is a computer program that causes a computer to execute a process for repeatedly charging and discharging a secondary battery to raise the temperature of the secondary battery. A process of setting the charging / discharging parameters in advance based on the parameters of the secondary battery required to set the charging / discharging parameters, and controlling charging / discharging of the secondary battery based on the set charging / discharging parameters. And processing.

The secondary battery temperature raising method according to the present embodiment is a secondary battery temperature raising method of repeatedly charging and discharging the secondary battery to raise the temperature of the secondary battery, wherein the charging and discharging parameters of the secondary battery are The charge / discharge parameters are set in advance based on the parameters of the secondary battery necessary for setting, and the charge / discharge of the secondary battery is controlled based on the set charge / discharge parameters.

(4) The setting unit sets the charge / discharge parameters in advance based on the parameters of the secondary battery required to set the charge / discharge parameters of the secondary battery. The charge / discharge current is a physical quantity that contributes to the heat generation of the secondary battery. When the resistance component of the secondary battery is R and the charge / discharge current is I, the heat generation is proportional to (I squared × R). That is, in order to shorten the heating time until the temperature of the secondary battery reaches the target value (or increase the heating rate), the charging / discharging current I may be increased within an allowable range. The charge / discharge parameter can be a parameter that can increase the charge / discharge current within an allowable range. The parameters of the secondary battery are parameters necessary for setting the charge / discharge parameters in advance (that is, setting the charge / discharge parameters before the charge / discharge current is supplied by the secondary battery temperature raising device).

(4) The control unit controls charging and discharging of the secondary battery based on the charging and discharging parameters set by the setting unit. That is, by performing charging and discharging of the secondary battery based on a preset charging and discharging parameter before flowing the charging and discharging current by the secondary battery heating device, for example, the current flowing through the secondary battery is detected and detected. Since it is not necessary to perform the charge / discharge operation by feedback-controlling the current, there is no delay in the processing associated with the feedback control. In addition, unstable operation due to transient fluctuation of the current of the secondary battery due to speeding up the feedback control processing does not occur.

With the above-described configuration, the charging / discharging operation by the secondary battery temperature raising device can be started using the set charging / discharging parameters, so that the temperature raising time until the temperature of the secondary battery reaches the target value is set. This can be shortened (or the rate of temperature rise can be increased), and the rate of temperature rise of the secondary battery can be improved.

In the secondary battery temperature raising device according to the present embodiment, the setting unit sets a duty ratio of a switching element included in a step-up / step-down circuit used for charging and discharging the secondary battery as the charge / discharge parameter.

The setting unit sets a duty ratio of a switching element included in the step-up / step-down circuit used for charging and discharging the secondary battery as a charging / discharging parameter. The charge current and the discharge current flowing through the secondary battery can be changed according to the duty ratio of the switching element. By setting the duty ratio according to the required charging / discharging current, the rate of temperature rise of the secondary battery can be improved.

In the secondary battery temperature raising device according to the present embodiment, the setting unit includes a first switching element as the switching element connected in series to the secondary battery included in the step-up / step-down circuit, and the second switching element. The duty ratio of each of the second switching elements as the switching elements connected in parallel to the next battery is set.

The setting unit sets the duty ratio of each of the first switching element connected in series to the secondary battery included in the step-up / step-down circuit and the second switching element connected in parallel to the secondary battery. When charging the secondary battery in the step-down mode of the step-up / step-down circuit and discharging the secondary battery in the step-up mode, the duty ratio of the first switching element is the duty ratio in the step-down mode, and the duty ratio of the second switching element. Is a duty ratio in the boost mode. By setting the duty ratio of each of the first switching element and the second switching element, the rate of temperature rise of the secondary battery can be improved according to the required charging current and discharging current of the secondary battery.

The secondary battery temperature raising device according to the present embodiment includes a detection unit that detects a state of the secondary battery, and an adjustment unit that adjusts a charge / discharge parameter of the secondary battery according to the state of the secondary battery. And

(4) The detecting section detects the state of the secondary battery. The state of the secondary battery is a state that affects a change in a preset charging / discharging parameter, and may be, for example, the temperature of the secondary battery.

(4) The adjusting unit adjusts the charge / discharge parameters of the secondary battery according to the state of the secondary battery. Thus, even if a state where the preset charging / discharging parameter changes occurs, the charging / discharging parameter can be adjusted, and a decrease in the rate of temperature rise of the secondary battery can be suppressed.

In the secondary battery temperature raising device according to the present embodiment, the detection unit detects the temperature of the secondary battery.

(4) The detecting section detects the temperature of the secondary battery. Depending on the temperature of the secondary battery, for example, parameters (for example, voltage, impedance, etc.) of the secondary battery change. Since the charge / discharge parameters of the secondary battery can be adjusted according to the temperature of the secondary battery, it is possible to adjust the charge / discharge parameters even when a state where the preset charge / discharge parameters change occurs. As a result, a decrease in the rate of temperature rise of the secondary battery can be suppressed.

The secondary battery heating device according to the present embodiment includes a voltage detection unit that detects a voltage of an auxiliary secondary battery that is discharged and charged in accordance with charging and discharging of the secondary battery, and the adjustment unit includes: The charge / discharge parameter of the secondary battery is adjusted according to the voltage of the auxiliary secondary battery.

The voltage detector detects the voltage of the auxiliary secondary battery that is discharged and charged according to the charging and discharging of the secondary battery. The voltage of the auxiliary secondary battery can be higher than the voltage of the secondary battery.

(4) The adjusting unit adjusts the charging / discharging parameters of the secondary battery according to the voltage of the auxiliary secondary battery. For example, when the voltage of the auxiliary secondary battery becomes higher than the upper limit, the charge / discharge parameter is adjusted so as to decrease the voltage of the auxiliary secondary battery. When the voltage of the auxiliary secondary battery becomes lower than the lower limit, the charge / discharge parameter is adjusted so as to increase the voltage of the auxiliary secondary battery.

According to the above configuration, when an auxiliary storage battery such as an electric double layer capacitor (EDLC) is used, which has a small capacity and a large voltage fluctuation range, the auxiliary secondary battery is used in an appropriate state. Can be.

に お い て In the secondary battery temperature raising device according to the present embodiment, the adjustment unit adjusts a duty ratio of the switching element.

The adjustment unit adjusts the duty ratio of the switching element. Thereby, the charge / discharge current of the secondary battery can be adjusted.

The secondary battery temperature raising device according to the present embodiment includes a ratio adjustment unit that adjusts a ratio between a charge period and a discharge period in a charge / discharge cycle of the secondary battery according to a voltage of the auxiliary secondary battery. Prepare.

(4) The ratio adjuster adjusts the ratio between the charge period and the discharge period in the charge / discharge cycle of the secondary battery according to the voltage of the auxiliary secondary battery. For example, when the voltage of the auxiliary secondary battery becomes higher than the upper limit, the ratio of the charging period of the secondary battery (discharge period of the auxiliary secondary battery) is increased so that the discharge current of the auxiliary secondary battery increases. . Further, when the voltage of the auxiliary secondary battery becomes lower than the lower limit value, the ratio of the discharging period of the secondary battery (the charging period of the auxiliary secondary battery) is increased so that the charging current of the auxiliary secondary battery increases. .

According to the above configuration, when an auxiliary storage battery such as an electric double layer capacitor (EDLC) is used, which has a small capacity and a large voltage fluctuation range, the auxiliary secondary battery is used in an appropriate state. Can be.

In the secondary battery temperature raising device according to the present embodiment, the parameters of the secondary battery are the voltage of the secondary battery, and the auxiliary secondary battery that is discharged and charged according to the charging and discharging of the secondary battery. Voltage.

パ ラ メ ー タ The parameters of the secondary battery include the voltage of the secondary battery and the voltage of the auxiliary secondary battery that is discharged and charged according to the charging and discharging of the secondary battery. Assuming that the voltage of the secondary battery is V1 and the voltage of the auxiliary secondary battery is V2, the duty ratio D1 in the step-down mode can be set by D1 = V2 / V1. Further, the duty ratio D2 in the boost mode can be set by D2 = (V2-V1) / V2.

に お い て In the secondary battery temperature raising device according to the present embodiment, the parameters of the secondary battery include the impedance of the secondary battery during a charge / discharge cycle of the secondary battery.

パ ラ メ ー タ The parameters of the secondary battery include the impedance of the secondary battery during the charge / discharge cycle of the secondary battery. Assuming that the charge / discharge cycle is Tc, the impedance Z of the secondary battery changes depending on the frequency f (= 1 / Tc). Assuming that the open-circuit voltage of the secondary battery is OCV1, the voltage V1 of the secondary battery can be represented by V1 = OCV1 + I × R. Here, I is a charge / discharge current of the secondary battery, and R is a real component of the impedance Z (f). As a result, the duty ratio D1 in the step-down mode and the duty ratio D2 in the step-up mode for obtaining the required charging / discharging current I can be set.

The secondary battery temperature raising device according to the present embodiment includes a step-up / step-down circuit that is used for charging and discharging the secondary battery and has a switching element that repeats on / off, and the control unit turns on the switching element. Turn off to control charging and discharging of the secondary battery.

昇 Equipped with a step-up / step-down circuit having a switching element that is used for charging and discharging the secondary battery and that repeats ON / OFF. The control unit can control charging / discharging of the secondary battery by turning on / off the switching element of the step-up / step-down circuit.

In the secondary battery temperature raising device according to the present embodiment, the step-up / step-down circuit includes a first switching element connected in series to the secondary battery, and a first switching element connected in parallel to the secondary battery. A second switching element, and the control unit controls charging and discharging of the secondary battery by turning on and off the first switching element and the second switching element.

(4) The step-up / step-down circuit includes a first switching element connected in series to the secondary battery, and a second switching element connected in parallel to the secondary battery. When charging the secondary battery in the step-down mode of the step-up / step-down circuit and discharging the secondary battery in the step-up mode, the duty ratio of the first switching element is the duty ratio in the step-down mode, and the duty ratio of the second switching element. Is a duty ratio in the boost mode.

The control unit can control charging and discharging of the secondary battery by turning on and off the first switching element and the second switching element.

The secondary battery temperature raising device according to the present embodiment includes the secondary battery and an auxiliary secondary battery, and the control unit charges the secondary battery by discharging the auxiliary secondary battery, The auxiliary secondary battery is charged and the secondary battery is discharged.

The control unit can discharge the auxiliary secondary battery to charge the secondary battery and charge the auxiliary secondary battery to discharge the secondary battery.

[Details of Embodiment of the Present Disclosure]
Hereinafter, a secondary battery temperature raising device according to the present embodiment will be described with reference to the drawings. FIG. 1 is a block diagram showing an example of a main configuration of a vehicle equipped with a controller 50 of the present embodiment. The vehicle includes a main battery 10 as a secondary battery, a sub-battery 20 as an auxiliary secondary battery, a DC / DC converter 30 as a step-up / step-down circuit, a controller 50, and the like. The secondary battery temperature raising device includes a controller 50. Further, the secondary battery temperature raising device may include at least one of the main battery 10, the sub battery 20, and the DC / DC converter 30 in addition to the controller 50.

The main battery 10 can be, for example, a lithium ion battery, and has a plurality of cells (not shown) connected in series or in series / parallel. The main battery 10 includes a voltage sensor 11, a current sensor 12, and a temperature sensor 13. The voltage sensor 11 detects the voltage of each cell and the voltage V1 across the main battery 10, and outputs the detected voltage V1 to the controller 50. The current sensor 12 includes, for example, a shunt resistor or a Hall sensor, and detects a charging current and a discharging current (collectively, a current I) of the main battery 10. The current sensor 12 outputs the detected current I to the controller 50. The temperature sensor 13 includes, for example, a thermistor and detects the temperature of each cell. The temperature sensor 13 may be configured to detect the temperature of all the cells of the plurality of cells, or may be configured to detect the temperature of some of the cells of the plurality of cells. The temperature of one predetermined cell may be detected. When the temperatures of a plurality of cells are detected, the average value, the median value, or the maximum value of the detected temperatures of the cells can be used as the detected temperature. The temperature sensor 13 outputs the detected temperature to the controller 50.

The main battery 10 can be used as an auxiliary battery, and is used, for example, for starting a hybrid system of a vehicle in response to operation of a start switch (ignition switch) (not shown) or for a backup memory during parking. Used as a power source for The rated voltage of the main battery 10 can be, for example, 12 V, but is not limited thereto.

The sub-battery 20 may be, for example, an electric double-layer capacitor (EDLC), and is used for an auxiliary power supply or regeneration. The sub-battery 20 includes a voltage sensor 21. The voltage sensor 21 detects a voltage V2 across the sub-battery 20 and outputs the detected voltage V2 to the controller 50. The rated voltage of the sub-battery 20 may be, for example, 24 V or 48 V, but is not limited thereto.

The DC / DC converter 30 forms a step-up / step-down circuit, and includes an FET 31 as a first switching element connected in series to the main battery 10 and a second switching element connected in parallel to the main battery 10 And an inductor (coil) 33. Diodes are connected between the drains and the sources of the FETs 31 and 32.

That is, in the DC / DC converter 30, one end of the inductor 33 is connected to the positive terminal of the main battery 10, the other end of the inductor 33 is connected to the source of the FET 31, and the drain of the FET 31 is connected to the positive terminal of the sub-battery 20. It is connected. The source of the FET 31 is connected to the drain of the FET 32, and the source of the FET 32 is connected to a predetermined reference potential (for example, 0 V). A control signal (gate signal) from the controller 50 is input to the gate of each of the FETs 31 and 32, and the FETs 31 and 32 are switched so as to alternately turn on and off.

Under the control of the controller 50, the DC / DC converter 30 charges the main battery 10 (that is, discharges the sub-battery 20) (buck mode) and discharges the main battery 10 (that is, discharges the sub-battery 20). It operates in a boosting operation (Boost mode).

In the step-down operation (buck mode), when the FET 31 is turned on (the FET 32 is turned off at this time), a current flows from the sub-battery 20 to the main battery 10, and energy is accumulated in the inductor 33. Next, when the FET 31 is turned off (at this time, the FET 32 is turned on), the energy stored in the inductor 33 is supplied to the main battery 10 through the FET 32, so that a charging current flows through the main battery 10. Here, the duty ratio of the FET 31 is referred to as the step-down duty ratio D1. The duty ratio of the FET 31 is a ratio of the ON state period to the total period of the ON state and the OFF state of the FET 31.

In the boosting operation (Boost mode), first, when the FET 32 is turned on (at this time, the FET 31 is turned off), a current flows from the main battery 10 through the inductor 33, and energy is accumulated in the inductor 33. Next, when the FET 32 is turned off (at this time, the FET 31 is turned on), the energy stored in the inductor 33 is supplied to the sub-battery 20 through the FET 31, so that a discharge current flows through the main battery 10. Here, the duty ratio of the FET 32 is referred to as a boost-side duty ratio D2. The duty ratio of the FET 32 is a ratio of the ON state period to the total period of the ON state and the OFF state of the FET 32.

FIG. 2 is a time chart showing an example of a current / voltage waveform of the main battery 10 and a voltage waveform of the sub-battery 20 during charging and discharging. The upper part of FIG. 2 shows the current of the main battery 10. For convenience, charging is performed when the current is positive, and discharging is performed when the current is negative. In the Buck mode, the main battery 10 is charged, and in the Boost mode, the main battery 10 is discharged. The total time of the time in the Buck mode and the time in the Boost mode corresponds to a charge / discharge cycle. For example, when charging and discharging are repeated 1000 times per second, the charging and discharging cycle is 1 ms.

の 下 The lower part of FIG. 2 shows the voltage of the main battery 10 and the voltage of the sub-battery 20. In the Buck mode, since the main battery 10 is charged and the sub-battery 20 is discharged, the voltage of the main battery 10 is higher than that at the time of discharging, and the voltage of the sub-battery 20 is lower than that at the time of charging. Further, in the boost mode, the main battery 10 is discharged and the sub-battery 20 is charged, so that the voltage of the main battery 10 is lower than at the time of charging, and the voltage of the sub-battery 20 is higher than at the time of discharging. Note that the waveforms of the voltage and the current are schematically illustrated, and therefore may be different from actual waveforms.

FIG. 3 is a time chart showing an example of the ON / OFF state of the FETs 31 and 32. FIG. 3 illustrates the on / off state of the FETs 31 and 32 during one charge / discharge cycle. The ON / OFF waveforms of the FETs 31 and 32 are shown for comparison with the charge / discharge cycle, and are schematically shown. The FETs 31 and 32 are alternately turned on and off alternately, and the switching cycle is T. The switching frequency of the FETs 31 and 32 can be, for example, several tens of kHz, but is not limited thereto.

(4) In the step-down operation (buck mode), when the ON period of the FET 31 is T1, the duty ratio D1 on the step-down side (step-down mode) can be expressed by D1 = T1 / T. In the boosting operation (Boost mode), assuming that the ON period of the FET 32 is T2, the duty ratio D2 on the boosting side (boost mode) can be expressed by D2 = T2 / T.

The controller 50 includes a voltage acquisition unit 51, a current acquisition unit 52, a temperature acquisition unit 53, a storage unit 54, and a processing unit 60. The processing unit 60 includes a control unit 61, a charge / discharge parameter setting unit 62, a charge / discharge parameter adjustment unit 63, and a charge / discharge cycle adjustment unit 64.

(4) The voltage acquisition unit 51 acquires the voltages of the plurality of cells of the main battery 10, the voltage V1 of the main battery 10, and the voltage V2 of the sub-battery 20. The current acquisition unit 52 acquires a current I (a charging current and a discharging current) of the main battery 10. The sampling period for acquiring the voltage and the current can be, for example, 10 ms, but is not limited to this. The temperature acquisition unit 53 acquires a cell temperature.

Each cell of the main battery 10 can be represented by an equivalent circuit composed of, for example, the resistance of the electrolytic solution bulk, the interface charge transfer resistance, the electric double layer capacitance, the diffusion impedance, and the like. For example, an equivalent circuit of a cell can be equivalently represented by a circuit in which an electric double layer capacitance is connected in parallel to a series circuit of interfacial charge transfer resistance and diffusion impedance, and a circuit in which the resistance of the electrolyte bulk is further connected in series. . Note that the equivalent circuit is not limited to this.

FIG. 4 is an explanatory diagram illustrating an example of an impedance spectrum of the main battery 10 in a low frequency region, and FIG. 5 is an explanatory diagram illustrating an example of an impedance spectrum of a resonance region of the main battery 10. 4 and 5, the horizontal axis represents the real component of the impedance, and the vertical axis represents the imaginary component of the impedance. When the impedance Z is represented by Z = R + jX, R is a real component and X is an imaginary component.

4 and 5, the curve indicated by the symbol A1 represents the impedance spectrum when the temperature of the main battery 10 is −30 ° C., and the curve indicated by the symbol A2 represents the impedance spectrum when the temperature of the main battery 10 is −20 ° C. A curve A3 represents an impedance spectrum when the temperature of the main battery 10 is −15 ° C., and a curve A4 represents an impedance spectrum when the temperature of the main battery 10 is −10 ° C. A curve indicated by A5 represents an impedance spectrum when the temperature of the main battery 10 is −5 ° C. FIG. 5 is an enlarged view of a region indicated by reference symbol S in FIG.

で は In the low frequency region shown in FIG. 4, as the frequency becomes lower, the impedance of the main battery 10 changes clockwise on the impedance spectrum. Further, in FIG. 5, numerical values shown near each curve represent frequencies. As the frequency becomes lower, the impedance of the main battery 10 changes from the lower side to the upper side on the impedance spectrum.

As shown in FIGS. 4 and 5, the impedance of the main battery 10 changes according to the frequency, and the change in the impedance accompanying the change in the frequency is an impedance spectrum. The resonance frequency is a frequency at which the impedance of the main battery 10 has an extreme value. FIG. 5 shows extreme impedance lines connecting the resonance frequencies on the impedance spectrum at each temperature. As can be seen from FIGS. 4 and 5, the impedance decreases as the frequency approaches the resonance frequency, and the impedance increases as the frequency moves away from the resonance frequency. When the temperature of the main battery 10 changes, the impedance spectrum of the main battery 10 also changes, and the resonance frequency also changes.

(4) When the main battery 10 is charged and discharged at a cycle corresponding to the resonance frequency, the inductance component of the main battery 10 is small, the main battery 10 easily generates heat, and the temperature raising efficiency is improved.

FIG. 6 is an explanatory diagram showing an example of resonance frequency information in which the resonance frequency of the main battery 10 is associated with the temperature. As shown in FIG. 6, when the temperature of the main battery 10 is −30 ° C., the resonance frequency is 6.1 kHz. When the temperature of the main battery 10 is 0 ° C., the resonance frequency is 1.0 kHz. Other relationships between the temperature and the resonance frequency are as shown in the figure. Note that the numerical values shown in FIG. 6 are merely examples, and are not limited to the example in FIG.

The storage unit 54 can store resonance frequency information in which the resonance frequency of the main battery 10 is associated with the temperature. In addition, the storage unit 54 can store an impedance spectrum (impedance characteristics, for example, an impedance value that changes according to a resonance frequency and a temperature) of the main battery 10 as illustrated in FIGS. 4 and 5.

The control unit 61 charges and discharges the main battery 10 based on the temperature of the main battery 10 acquired by the temperature acquisition unit 53 and the resonance frequency information stored in the storage unit 54 before operating the DC / DC converter 30. In this case, the charge / discharge cycle can be determined. For example, when the resonance frequency is 1 kHz, the control unit 61 can determine 1 ms, which is the reciprocal of 1 kHz, as the charge / discharge cycle. Thereby, the main battery 10 can be charged and discharged in the charging and discharging cycle corresponding to the frequency at which the inductance component of the main battery 10 is small, and the temperature of the main battery 10 can be efficiently raised.

The charging / discharging parameter setting unit 62 has a function as a setting unit, and presets charging / discharging parameters based on parameters of the main battery 10 necessary for setting the charging / discharging parameters of the main battery 10. The charge / discharge current is a physical quantity that contributes to the heat generation of the main battery 10. If the resistance component of the impedance Z of the main battery 10 is R and the charge / discharge current is I, the heat generation amount is (I square × R). Proportional.

{That is, in order to shorten the time required for the temperature of the main battery 10 to reach the target value (or to increase the rate of temperature increase), the charge / discharge current I may be increased within an allowable range. The charge / discharge parameter can be a parameter that can increase the charge / discharge current within an allowable range. The parameters of the main battery 10 are parameters necessary for setting the charge / discharge parameters in advance (that is, setting the charge / discharge parameters before the controller 50 operates the DC / DC converter 30).

The control unit 61 controls the switching operation of the FETs 31 and 32 based on the charging / discharging parameters set by the charging / discharging parameter setting unit 62 to control the charging / discharging of the main battery 10.

That is, before the DC / DC converter 30 is operated by the controller 50 (before the charging / discharging current is supplied), the main battery 10 is charged / discharged based on a preset charging / discharging parameter, so that, for example, Since there is no need to detect the flowing current and perform the charge / discharge operation by performing feedback control on the detected current, there is no delay in the processing associated with the feedback control. In addition, unstable operation due to transient fluctuation of the current of the secondary battery due to speeding up the feedback control processing does not occur.

With the above-described configuration, the charge / discharge operation by the controller 50 can be started using the set charge / discharge parameters, so that the time required for the temperature of the main battery 10 to reach the target value is shortened (or Thus, the rate of temperature rise of the main battery 10 can be improved.

The charge / discharge parameter setting unit 62 can set the duty ratio of the FETs 31 and 32 of the DC / DC converter 30 as a charge / discharge parameter. The charging current and the discharging current flowing to the main battery 10 can be changed according to the duty ratio of the FETs 31 and 32. By setting the duty ratio according to the required charging / discharging current, the temperature rising speed or the temperature rising time of the main battery 10 can be improved.

More specifically, in the step-down operation of charging the main battery 10, the charge / discharge parameter setting unit 62 can set the duty ratio of the FET 31 (step-down duty ratio D1). In the boosting operation for discharging the main battery 10, the charge / discharge parameter setting unit 62 can set the duty ratio of the FET 32 (the duty ratio D2 on the boosting side).

Thereby, the temperature rising speed (or temperature rising time) of the main battery 10 can be improved according to the required charging current and discharging current of the main battery 10.

Next, a method of setting the charging and discharging parameters based on the parameters of the main battery 10 and the sub-battery 20 will be described.

Assuming that the voltage of the main battery 10 is V1 and the voltage of the sub-battery 20 is V2, the step-down duty ratio D1 can be set by D1 = V2 / V1. Further, the duty ratio D2 on the boosting side can be set by D2 = (V2-V1) / V2.

The voltage V1 of the main battery 10 can be represented by V1 = OCV1 + I × R. Here, OCV1 is the open voltage of the main battery 10, R is the resistance component (real component) of the impedance Z of the main battery 10, and I is the charge / discharge current of the main battery 10. In this case, the step-down side duty ratio D1 can be set by D1 = V2 / (OCV1 + I × R), and the step-up side duty ratio D2 is set by D2 = {V2- (OCV1 + I × R)} / V2. can do. Although the voltage drop on the sub-battery 20 side can be ignored, the voltage drop can be considered.

FIG. 7 is an explanatory diagram showing an example of the correlation between the open voltage of the main battery 10 and the charging rate. In FIG. 7, the horizontal axis represents the open circuit voltage (OCV), and the vertical axis represents the state of charge (SOC). As shown in FIG. 7, as the charging rate of the main battery 10 increases, the open-circuit voltage increases. The correlation between the open-circuit voltage and the charging rate illustrated in FIG. 7 may be stored in the storage unit 54, or may be calculated by an arithmetic circuit.

The control unit 61 can calculate (estimate) the open-circuit voltage OCV1 of the main battery 10 using the state of charge (SOC) calculated based on the charging / discharging history of the main battery 10. Further, the control unit 61 can calculate the resistance component R of the impedance Z of the main battery 10 based on the information as shown in FIGS.

Accordingly, it is possible to set the step-down side duty ratio D1 and the step-up side duty ratio D2 for obtaining the required charge / discharge current I.

FIG. 8 is a schematic diagram showing an example of the relationship between the charging current of the main battery 10 and the duty ratio D1 on the step-down side. In the figure, the horizontal axis indicates the charging current, and the vertical axis indicates the duty ratio. As shown in FIG. 8, the required step-down duty ratio D1 can be set according to the current required to raise the temperature of the main battery 10 to the target temperature within the required time. For example, the duty ratio D1 on the step-down side may be increased as the target current increases. As the duty ratio D1 on the step-down side, for example, numerical values such as 0.51, 0.52, 0.53, 0.54, and 0.55 can be used, but the present invention is not limited to these numerical values.

FIG. 9 is a schematic diagram showing an example of the relationship between the discharge current of the main battery 10 and the duty ratio D2 on the boost side. In the figure, the horizontal axis indicates the charging current, and the vertical axis indicates the duty ratio. As shown in FIG. 9, the required boost duty ratio D2 can be set according to the current required to raise the temperature of the main battery 10 to the target temperature within the required time. For example, the duty ratio D2 on the boosting side may be reduced as the target current increases. As the duty ratio D2 on the boosting side, for example, numerical values such as 0.49, 0.48, 0.47, 0.46, and 0.45 can be used, but are not limited to these numerical values.

In the above example, before starting the temperature raising operation by charging and discharging the main battery 10, the temperature of the main battery 10 is detected, and the duty ratio D1 on the step-down side and the duty ratio D2 on the step-up side are set in advance. The configuration is such that the main battery 10 is charged and discharged using the set duty ratios D1 and D2 until the battery 10 reaches the target temperature, but is not limited to this. For example, after charging / discharging of the main battery 10 is started, the temperature of the main battery 10 may be sequentially detected, and the preset duty ratio D1 on the step-down side and the duty ratio D2 on the step-up side may be adjusted.

{That is, the temperature acquisition unit 53 has a function as a detection unit that detects the state of the main battery 10, and acquires the temperature of the main battery 10. The state of the main battery 10 is a state that affects the change of the preset charging / discharging parameters (the duty ratio D1 on the step-down side and the duty ratio D2 on the step-up side). But not limited to temperature.

The charge / discharge parameter adjustment unit 63 has a function as an adjustment unit, and can adjust the charge / discharge parameters of the main battery 10 according to the state of the main battery 10.

Specifically, the charge / discharge parameter adjustment unit 63 can adjust the duty ratio D1 on the step-down side and the duty ratio D2 on the step-up side, and can adjust the charge / discharge current of the main battery 10.

Accordingly, even when a state in which the preset charging / discharging parameter changes occurs, the charging / discharging parameter can be adjusted, and a decrease in the rate of temperature rise of the main battery 10 can be suppressed.

パ ラ メ ー タ Further, parameters (for example, voltage, impedance, and the like) of the main battery 10 fluctuate according to the temperature of the main battery 10. Since the charge / discharge parameter adjustment unit 63 can adjust the charge / discharge parameters of the main battery 10 according to the temperature of the main battery 10, even if a state where a preset charge / discharge parameter changes occurs, The charge / discharge parameters can be adjusted, and a decrease in the rate of temperature rise of the main battery 10 (or a prolonged temperature rise time) can be suppressed.

Next, a method for preventing the sub-battery 20 from being overcharged or overdischarged will be described.

FIGS. 10A, 10B, and 10C are schematic diagrams showing an example of the voltage waveform of the sub-battery 20. FIG. As illustrated in FIG. 2, the voltage of the sub-battery 20 varies with the charging and discharging of the main battery 10. In the state of FIG. 10A, the voltage of the sub-battery 20 changes between the upper limit value and the lower limit value (for example, the average voltage is 20 V).

10B, in the state of FIG. 10B, the average voltage has increased to 22 V and the voltage of the sub-battery 20 has exceeded the upper limit value as compared with the state of FIG. 10A. In this case, it is necessary to discharge the sub-battery 20 in order to suppress overcharging (overvoltage).

状態 In the state of FIG. 10C, the average voltage is reduced to 2 V, and the voltage of the sub-battery 20 is lower than the lower limit, as compared with the state of FIG. 10A. In this case, it is necessary to charge the sub-battery 20 in order to suppress overdischarge.

The charging / discharging cycle adjusting unit 64 has a function as a ratio adjusting unit, and can adjust the ratio between the charging period and the discharging period in the charging / discharging cycle of the main battery 10 according to the voltage of the sub-battery 20. .

FIG. 11 is an explanatory diagram showing an example of a method of adjusting the charging period and the discharging period in the charging / discharging cycle of the main battery 10. In the first adjustment example, assuming that the charging and discharging cycle is Tc, the charging period (Buck) and the discharging period (Boost) are each Tc / 2. That is, the charging period and the discharging period are the same.

In the second adjustment example, the charging period (Buck) is Tc / 2 + ΔTc, and the discharging period (Boost) is Tc / 2−ΔTc. Thereby, as shown in FIG. 10B, when the voltage of sub-battery 20 exceeds the upper limit, the discharging period of main battery 10 (that is, the charging period of sub-battery 20) is shortened, and the charging period of main battery 10 ( That is, the discharge period of the sub-battery 20) can be lengthened so that the voltage of the sub-battery 20 becomes lower than or equal to the upper limit.

In the third adjustment example, the charging period (Buck) is Tc / 2−ΔTc, and the discharging period (Boost) is Tc / 2 + ΔTc. Thereby, as shown in FIG. 10C, when the voltage of sub-battery 20 falls below the lower limit, the discharging period of main battery 10 (that is, the charging period of sub-battery 20) is lengthened, and the charging period of main battery 10 ( That is, the discharge period of the sub-battery 20) can be shortened so that the voltage of the sub-battery 20 becomes higher than or equal to the lower limit.

With the above-described configuration, for example, when a small-capacity power storage device such as an electric double layer capacitor (EDLC) having a large voltage fluctuation range is used as the sub-battery 20, the sub-battery 20 can be used in an appropriate state. .

(4) The charge / discharge parameter adjustment unit 63 can adjust the charge / discharge parameters of the main battery 10 according to the voltage of the sub-battery 20. For example, as shown in FIG. 10B, when the voltage of the sub-battery 20 becomes higher than the upper limit value, the charge / discharge parameter can be adjusted so as to lower the voltage of the sub-battery 20. For example, the charge current of the main battery 10 increases (or the discharge current of the sub-battery 20 increases), or the discharge current of the main battery 10 decreases (or the charge current of the sub-battery 20 decreases). As a result, at least one of the duty ratio D1 on the step-down side and the duty ratio D2 on the step-up side can be adjusted.

Also, as shown in FIG. 10C, when the voltage of the sub-battery 20 becomes lower than the lower limit, the charge / discharge parameter can be adjusted so as to increase the voltage of the sub-battery 20. For example, the charge current of the main battery 10 decreases (or the discharge current of the sub-battery 20 decreases), or the discharge current of the main battery 10 increases (or the charge current of the sub-battery 20 decreases). (To increase), at least one of the step-down side duty ratio D1 and the step-up side duty ratio D2 can be adjusted.

With the above-described configuration, for example, when a small-capacity power storage device such as an electric double layer capacitor (EDLC) having a large voltage fluctuation range is used as the sub-battery 20, the sub-battery 20 can be used in an appropriate state. .

FIG. 12 is a flowchart showing an example of the processing procedure of the controller 50. The controller 50 acquires the temperature of the main battery 10 (S11). Here, the temperature can be obtained by obtaining the temperature detected by the temperature sensor 13. The controller 50 specifies a charge / discharge cycle of the main battery 10 (S12). The charge / discharge cycle can be determined from the resonance frequency of the main battery 10 based on the acquired temperature. Note that the charge / discharge cycle can be determined in advance.

(4) The controller 50 specifies the impedance of the main battery 10 based on the acquired temperature (S13). The controller 50 specifies the voltage V1 of the main battery 10 and the voltage V2 of the sub battery 20 (S14).

(4) The controller 50 sets the duty ratio D1 on the step-down side (S15), and sets the duty ratio D2 on the step-up side (S16). The controller 50 starts charging / discharging of the main battery 10 (S17), and determines whether the temperature of the main battery 10 has reached a target value (S18).

If the temperature of the main battery 10 has not reached the target value (NO in S18), the controller 50 determines whether the state of the main battery 10 has changed (S19). Here, the state of the main battery 10 can be the temperature of the main battery 10. Note that the temperature change determined to have a state change may be, for example, a temperature change to a certain extent that it is necessary to adjust (reset) at least one of the step-down side duty ratio D1 and the step-up side duty ratio D2. .

If the state of the main battery 10 has changed (YES in S19), the controller 50 performs the processing from step S15. In this case, at least one of steps S15 and S16 may be performed. Thereby, at least one of the step-down side duty ratio D1 and the step-up side duty ratio D2 can be adjusted (reset).

If the state of the main battery 10 has not changed (NO in S19), the controller 50 performs the processing in step S18. If the temperature of main battery 10 has reached the target value (YES in S18), controller 50 ends the process.

The controller 50 of the present embodiment can also be realized using a general-purpose computer including a CPU (processor), a RAM (memory), and the like. That is, as shown in FIG. 12, a computer program that defines the procedure of each process is loaded into a RAM (memory) provided in the computer, and the computer program is executed by a CPU (processor). Alternatively, the processing unit 60 can be realized.

As described above, according to the present embodiment, it is possible to prevent a delay associated with feedback control and to achieve faster switching between charge and discharge as compared with a conventional DC / DC converter that performs feedback control of current or voltage. That is, the charge / discharge cycle can be shortened. Further, it is possible to avoid occurrence of a transient excessive current due to overshoot or the like due to excessive feedback control.

In the above-described embodiment, the DC / DC converter 30 has a configuration including two FETs. However, the configuration is not limited to this. For example, a configuration including four FETs may be used.

In the above embodiment, the controller 50 is described as an example of the secondary battery temperature raising device, but the present invention is not limited to this. For example, the secondary battery temperature raising device may be configured to include any or all of the main battery 10, the sub-battery 20, and the DC / DC converter 30 in addition to the controller 50.

The disclosed embodiments are to be considered in all respects as illustrative and not restrictive. The scope of the present disclosure is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

Reference Signs List 10 main battery 11, 21 voltage sensor 12 current sensor 13 temperature sensor 20 sub-battery 30 DC / DC converter 31, 32 FET
33 Inductor 50 Controller 51 Voltage acquisition unit 52 Current acquisition unit 53 Temperature acquisition unit 54 Storage unit 60 Processing unit 61 Control unit 62 Charge / discharge parameter setting unit 63 Charge / discharge parameter adjustment unit 64 Charge / discharge cycle adjustment unit

Claims (15)

A secondary battery heating device that repeatedly charges and discharges the secondary battery and raises the temperature of the secondary battery,
A setting unit for setting the charge / discharge parameters in advance based on the parameters of the secondary battery required to set the charge / discharge parameters of the secondary battery,
A control unit that controls charging and discharging of the secondary battery based on the charging and discharging parameters set by the setting unit. The setting unit includes:
The secondary battery temperature raising device according to claim 1, wherein a duty ratio of a switching element included in a step-up / down circuit used for charging and discharging the secondary battery is set as the charge / discharge parameter. The setting unit includes:
A first switching element as the switching element connected in series to the secondary battery of the step-up / step-down circuit, and a second switching as the switching element connected in parallel to the secondary battery The secondary battery temperature raising device according to claim 2, wherein a duty ratio of each element is set. A detection unit that detects a state of the secondary battery,
4. The secondary battery temperature raising device according to claim 1, further comprising: an adjustment unit configured to adjust a charge / discharge parameter of the secondary battery according to a state of the secondary battery. 5. The detection unit,
The secondary battery temperature raising device according to claim 4, wherein the temperature of the secondary battery is detected. A voltage detection unit that detects the voltage of the auxiliary secondary battery that is discharged and charged according to the charging and discharging of the secondary battery,
The adjustment unit is
The secondary battery temperature raising device according to claim 4 or 5, wherein a charge / discharge parameter of the secondary battery is adjusted according to a voltage of the auxiliary secondary battery. The adjustment unit is
The secondary battery temperature raising device according to any one of claims 4 to 6, wherein a duty ratio of the switching element is adjusted. 7. The secondary battery temperature raising device according to claim 6, further comprising: a ratio adjustment unit that adjusts a ratio between a charge period and a discharge period in a charge / discharge cycle of the secondary battery according to a voltage of the auxiliary secondary battery. The parameters of the secondary battery are as follows:
The voltage of the secondary battery,
The secondary battery temperature raising device according to any one of claims 1 to 8, further comprising: a voltage of an auxiliary secondary battery that is discharged / charged in accordance with charging / discharging of the secondary battery. The parameters of the secondary battery are as follows:
The secondary battery temperature raising device according to any one of claims 1 to 9, including an impedance of the secondary battery in a charge / discharge cycle of the secondary battery. Used for charging and discharging the secondary battery, comprising a buck-boost circuit having a switching element that repeats on and off,
The control unit includes:
The secondary battery temperature raising device according to any one of claims 1 to 10, wherein the switching element is turned on and off to control charging and discharging of the secondary battery. The buck-boost circuit,
A first switching element connected in series to the secondary battery;
A second switching element connected in parallel to the secondary battery,
The control unit includes:
The secondary battery temperature raising device according to claim 11, wherein the first switching element and the second switching element are turned on and off to control charging and discharging of the secondary battery. The secondary battery;
With an auxiliary secondary battery,
The control unit includes:
The secondary battery according to claim 1, wherein the auxiliary secondary battery is discharged to charge the secondary battery, and the auxiliary secondary battery is charged to discharge the secondary battery. Battery heating device. A computer program for causing a computer to execute processing for repeatedly charging and discharging a secondary battery to raise the temperature of the secondary battery,
On the computer,
Based on the parameters of the secondary battery required to set the charging and discharging parameters of the secondary battery, a process of setting the charging and discharging parameters in advance,
A process of controlling charging and discharging of the secondary battery based on the set charging and discharging parameters. A secondary battery heating method for increasing the temperature of the secondary battery by repeating charging and discharging of the secondary battery,
Based on the parameters of the secondary battery required to set the charge and discharge parameters of the secondary battery, the charge and discharge parameters are set in advance,
A secondary battery temperature raising method for controlling charging and discharging of the secondary battery based on set charging / discharging parameters.

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