JP2012216422A - Reduction in temperature variance between batteries - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a temperature control method and system for reducing temperature variance between cells in order to suppress deterioration variance in units of cells.SOLUTION: Temperature measurement parts are arranged to be in contact with a cell and another cell, respectively. The temperature measurement parts measure cell temperatures and send the measured temperatures to a control unit. A Peltier element is arranged in a gap between the cells. In accordance with the difference between the temperatures of the cells measured by the temperature measurement parts, the control unit determines the direction and magnitude of an input current to be supplied to the Peltier element, and sends a signal to a DDC. The DDC includes a DC-DC converter circuit and receives the signal from the control unit to thereby serve as a control circuit for controlling the direction and magnitude of the input current supplied to the Peltier element.

Description

  The present invention relates to a temperature control method and system for reducing battery temperature variations.

  The life of the battery is sensitive to temperature, and therefore adjusting the temperature accurately leads to the extension of the battery life. There is a range where the battery has an appropriate temperature, and when the battery deviates from the range, that is, when the excessively high temperature state or the low temperature state continues, deterioration occurs.

  Conventionally, an apparatus and a method for adjusting the temperature of a battery using a Peltier element as a heating and cooling means have been proposed. In Patent Document 1, when the battery temperature is high, the Peltier element generates heat, and an electric current flows in the direction in which the inner side that is in close contact with the battery absorbs heat. Conversely, when the battery temperature is low, the Peltier element A temperature control device is disclosed in which a current is supplied so as to heat by heating. Patent Document 2 discloses a device that heats the secondary battery by applying the residual heat of the Peltier element during charging and standby when the secondary battery is discharged. Further, in Patent Document 3, when the secondary battery is higher than the target temperature, a current that causes the Peltier element to act as a cooling means is passed, and when the secondary battery is lower than the target temperature, the Peltier element is heated. A method and apparatus for passing a current to act as is disclosed.

  Each of these apparatuses and methods switches between heat generation and heat absorption of the Peltier element and performs only heating or cooling. In addition, since the temperature of a wide area is adjusted at a time, energy loss due to thermal diffusion is large, and the amount of heat required is large, and as a result, the amount of current flowing through the Peltier element is large. In addition, there is a problem that a temperature difference is easily generated in each cell, and the degree of deterioration is likely to vary.

  In general, a plurality of cells, which are individual batteries, gather together to form a module, and a plurality of modules gather together to form a pack. FIG. 1 is a diagram illustrating the relationship between packs, modules, and cells. As shown in FIG. 1, a plurality of cells 1, each of which is an individual battery, are connected in series to form a single module 2, and a plurality of modules 2 connected in parallel to a single pack 3. Become. As an example, a case where 50 V 1 cells 1 are connected in series to form a 200 V module 2 can be considered.

  For example, if only a certain part in the module or pack is located near the heat generating part such as an engine, the deterioration of the cell due to temperature changes due to changes over time, and the deteriorated cell and the usable cell Will be mixed. Since it is not possible to replace only one cell that has become unusable due to deterioration, it is assumed that at least modules must be replaced, and the result is that even unusable usable cells are discarded. I was invited. Therefore, in order to use the life of the pack and the module effectively, it is necessary to suppress variation in deterioration in units of cells, that is, temperature adjustment in units of cells is very important.

  Patent Document 4 discloses an apparatus and method for heating or cooling a battery cell by detecting the temperature of the battery cell with a temperature sensor and changing the direction of the current flowing through the Peltier element according to the temperature. In this apparatus and method, only the direction of current is controlled according to the temperature of the battery cell, and no method for changing the amount of current flowing through the Peltier element is disclosed. I can't do it.

  In Patent Document 5, a Peltier element is arranged between the positive electrode terminal of a single cell and the negative electrode terminal of the other single cell, and when a direct current is applied to the element, the positive electrode terminal of one single cell is connected. An assembled battery that heats and cools the counter negative electrode terminal of the other unit cell is disclosed. In this method, the current supplied to the Peltier element between the electrode terminals is controlled to perform heating and cooling at the same time, but a method for changing the amount of current supplied to the Peltier element due to the temperature difference between the electrode terminals is not disclosed. Therefore, it is not possible to perform temperature adjustment with good accuracy in cell units.

JP-A-8-148189 JP 2006-196296 A JP 2008-10295 A Japanese Patent Laid-Open No. 11-176487 JP 2010-113861 A

  The present invention has been made in view of the above-described problems, and it is an object of the present invention to provide a temperature adjustment method and system for reducing cell temperature variation in order to suppress variation in cell-by-cell deterioration.

  A system according to one aspect of the present invention includes a first module having one or more cells, a second module having one or more cells, the first module, and the second module. A temperature measuring unit disposed on a surface of each module; a Peltier element disposed between the first module and the second module; and from the temperature measuring unit, the first and second modules. A controller that acquires a temperature and controls a current that flows through the Peltier element, wherein the controller is configured to control the Peltier according to a difference between a temperature of the first module and a temperature of the second module. The direction and the magnitude of the current flowing through the element are controlled.

  In the system according to the present invention described above, when the difference between the temperature of the first module and the temperature of the second module falls within a predetermined range, the control unit includes the Peltier element. You may comprise so that it may control so that an electric current may not be sent.

  At this time, the control unit may be configured to control the direction and magnitude of the current flowing through the Peltier element by transmitting a signal to the DC / DC converter circuit.

  According to another aspect of the present invention, there is provided a method of acquiring a temperature of a first module having one or more cells, and acquiring a temperature of a second module having one or more cells; The direction and the magnitude of the current flowing in the Peltier element arranged between the first module and the second module are controlled according to the temperature difference between the first module and the second module. And the step of performing.

  In the above-described method according to the present invention, when the difference between the temperature of the first module and the temperature of the second module is within a predetermined range, the current is not supplied to the Peltier element. The method may further include a step of controlling.

  At this time, a step of controlling the direction and magnitude of the current flowing through the Peltier element by transmitting a signal to the DC / DC converter circuit may be further included.

  In addition, even if it is a program for causing a computer to perform the method according to the present invention described above, since the program is executed by the computer, the same operations and effects as the method according to the present invention described above are achieved. The aforementioned problems are solved.

  A system according to one aspect of the present invention includes a plurality of modules having one or more cells, a temperature measurement unit disposed on a surface of each of the plurality of modules, and a plurality of modules disposed adjacent to each other. A plurality of Peltier elements, and a control unit that obtains temperatures of the plurality of modules from the temperature measurement unit and controls currents that flow through the plurality of Peltier elements, the control unit including the plurality of modules The direction and the magnitude of the current flowing through the plurality of Peltier elements are controlled according to the temperature difference.

  According to the present invention, it is possible to make the temperature difference between the cells constant and maximize the lifetime of the module and the entire pack by doing the above. Moreover, since both heat absorption and heat generation can be used for temperature adjustment at a time, it is possible to effectively use energy for making the temperature difference constant.

It is a figure which shows the relationship between a pack, a module, and a cell. It is a block diagram which shows the structure of the temperature control system which concerns on one Embodiment of this invention. It is a figure which shows an example of arrangement | positioning of the cell in the system shown by FIG. 2, a Peltier device, and the thermistor. It is a figure which shows the relationship between the temperature of the cell in the system shown by FIG. 2, the heat_generation | fever of a Peltier device, and heat absorption. It is a figure which shows the control circuit which controls the electric current sent through a Peltier device in the system shown by FIG. It is a flowchart implemented in order to perform control shown by FIG. It is a block diagram which shows the structure of the temperature control system which concerns on another embodiment of this invention. It is a figure which shows an example of arrangement | positioning of the cell in the system shown by FIG. 7, a Peltier device, and a thermistor. It is a figure which shows the relationship between the temperature of the cell, the heat_generation | fever of a Peltier device, and heat absorption in the system shown by FIG. It is a flowchart implemented in order to perform control shown by FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that matters other than matters specifically mentioned in the present specification and necessary for the implementation of the present invention can be understood by those skilled in the art based on the prior art in this technical field. The present invention can be carried out based on the contents disclosed in the present specification and common general technical knowledge in the technical field.

FIG. 2 is a block diagram showing a configuration of a temperature control system according to an embodiment of the present invention, and includes a first example of a temperature control system for implementing the present invention.
2 includes a cell 4 and a cell 5, a temperature measurement unit 6, a Peltier element 7, a control unit 8, and a DDC 9.

The cell 4 and the cell 5 include a battery such as a dry battery.
The temperature measurement unit 6 is arranged so as to be in contact with each of the cell 4 and the cell 5, and has a function of measuring the temperature of the cell 4 and the cell 5 and transmitting the measured temperature to the control unit 8. In FIG. 1, the temperature measuring unit 6 may be arranged at any place, at least one place, as long as the representative temperature of each cell can be measured. The temperature measurement unit 6 includes, for example, a temperature sensor such as a thermistor or a thermocouple.

The Peltier element 7 is disposed in the gap between the cell 4 and the cell 5. The Peltier element 7 is not in contact with the cells 4 and 5.
The control unit 8 determines the direction and magnitude of the input current flowing through the Peltier element 7 according to the difference between the temperature of the cell 4 and the temperature of the cell 5 measured by the temperature measurement unit 6, and transmits a signal to the DDC 9. It plays the role of controlling by doing.

The DDC 9 includes a DC / DC converter circuit, receives a signal from the control unit 8, and functions as a control circuit that controls the direction and magnitude of the input current that flows through the Peltier element 7.
A Peltier element is a plate-like semiconductor element that uses the Peltier effect in which heat is transferred from one metal to the other when a current is passed through the junction between two different types of metals or an n-type semiconductor and a p-type semiconductor. It is. When a direct current is passed through the Peltier element, one surface absorbs heat and the opposite surface generates heat. When the polarity of the current is reversed, the relationship is reversed and it is suitable for high-precision temperature control.

  In the temperature control system according to the present invention, the direction of heat absorption and heat generation of the Peltier element can be switched, and the amount of heat generation and heat absorption can be controlled by the amount of current flowing through the Peltier element. Use. In the temperature control system according to the present invention, by using both heat absorption and heat generation for temperature control, energy loss can be reduced and the amount of current flowing through the Peltier element can be reduced. Further, by reducing the temperature variation that occurs between cells, it is possible to effectively use the lifetime from the viewpoint of the lifetime of the entire module or pack.

  FIG. 3 is a diagram showing an example of the arrangement of cells, Peltier elements, and thermistors in the system shown in FIG. The left side of FIG. 3 schematically shows the arrangement of cells, Peltier elements, and thermistors, and the right side shows a cross section thereof.

  Peltier elements 11 are arranged in the gaps between the cells 10. At this time, in order to increase the heat transfer efficiency at the time of heating and cooling of the cell, it is desirable to make the structure as dense as possible and to make the Peltier element 11 as thin as possible to reduce the volume of the entire pack.

  The thermistor 12 is shown as an example of the temperature measurement unit 6 in FIG. One or more thermistors 12 may be arranged at any location where the representative temperature of each cell 10 can be measured.

  FIG. 4 is a diagram showing the relationship between the temperature of the cell and the heat generation and heat absorption of the Peltier element in the system shown in FIG. A Peltier element 7 is disposed in the gap between the cells 4 and 5. In FIG. 4, the temperature measurement unit 6, the control unit 8, and the DDC 9 shown in FIG. 2 are omitted.

The temperature of the cell 4 is T ₁ , the temperature of the cell 5 is T ₂ , the amount of heat generated from the Peltier element 7 to the cell 4 is Q _w , the amount of heat absorbed by the Peltier element 7 from the cell 5 is Q _c , and the Peltier The current flowing through the element 7 is i. When the temperature T ₁ <T ₂ , as shown in the left side of FIG. 4, the Peltier element 7 absorbs heat from the cell 5 so that a current flows in a direction in which the cell 4 generates heat. Take control. In this case, i flows in the positive direction. Conversely, when the temperature T ₁ > T ₂ , the Peltier element 7 absorbs heat from the cell 4 and generates heat to the cell 5 as shown on the right side of FIG. Control is performed so that a current flows. In this case, i flows in the negative direction.

When the heat capacity of the cell 4 is C ₁ , the heat capacity of the cell 5 is C ₂ , and the temperature at the time of thermal equilibrium is T, the following two equations are established.

If the above two expressions are arranged with respect to T, the following expression is established.

Here, when the thermoelectric power of the Peltier element 7 is α, the internal resistance of the Peltier element 7 is R, and the thermal conductance of the Peltier element 7 is K, the following two equations are established.

By using Equation 4 and Equation 5 and solving Equation 3 for i, the magnitude and direction of the current i flowing through the Peltier element 7 can be obtained. As described above, the magnitude and direction of the current i flowing through the Peltier element 7 can be determined according to the difference between the temperature T ₁ of the cell 4 and the temperature T _{2 of the} cell 5.

  FIG. 5 is a diagram showing a control circuit for controlling the current flowing in the Peltier element in the system shown in FIG. 2, and includes an embodiment of DDC. In FIG. 5, the temperature measurement unit 6 shown in FIG. 2 is omitted.

  The DDC 9 includes a DC / DC converter circuit, plays a role of a control circuit that receives a signal from the control unit 8 and controls the direction and magnitude of the input current that flows through the Peltier element 7.

  One embodiment of the circuit of the DDC 9 is as shown in FIG. 5 and basically operates in the same manner as a conventional DC / DC converter, and its operation method is obvious to those skilled in the art. Therefore, the description of the detailed circuit operation method is omitted. In the present embodiment, the DDC 9 connects the cell 4 that is the object of temperature adjustment between the positive electrode 13 and the negative electrode 14, and reduces the voltage of the cell 4 between the A terminal 15 and the B terminal 16. It plays a role of applying the voltage when a current is passed through the connected Peltier elements 7. In the present specification, a circuit in which the cell 4 is connected between the positive electrode 13 and the negative electrode 14 is shown as an example. However, this is not limited to the cell 4, and the cell 5 It may be connected.

  The control board 17 in the DDC 9 performs various analog controls by receiving various signals from the control unit 8. For example, the POLE signal is received and the polarity is switched, and the direction of the current flowing through the Peltier element 7 is changed. Furthermore, the magnitude | size of the electric current sent through the Peltier device 7 is controlled by receiving a PWM (Pulse Width Modulation: pulse width modulation) signal from the control part 8, and changing a duty ratio.

  The ON / OFF signal switches the control board 17 between ON and OFF. The Signal GND signal provides the signal GND, the DC 14 V supplies the direct current 14 V, and the GND plays a role of providing the GND of the control board 17.

FIG. 6 is a flowchart executed to perform the control shown in FIG.
First, for example, when the engine of the automobile is started, the control unit 8 is started, and each circuit is turned on (step S1).

  Subsequently, the temperature measuring unit 6 measures the temperature of each of the cells 4 and 5 and transmits it to the control unit 8 (step S2). The control unit 8 that has received the temperatures of the cells 4 and 5 calculates the current i that flows through the Peltier element 7 by solving Equation 3 (step S3).

Subsequently, the calculated current i is compared with the threshold current i _th (step S4). If i> i _th (yes), the process proceeds to step S5, and i> i _th is not satisfied (no ), The process proceeds to step S6. In step S5, control is performed so that a current of magnitude i flows in the positive direction through the Peltier element 7. On the other hand, in step S6, a comparison of the -i and _{i th} is performed, in the case of -i _{<i th} (yes), the process proceeds to step S7, not -i _{<i th} (no) if Returns to step S2. In step S <b> 7, control is performed so that a current of magnitude i flows through the Peltier element 7 in the negative direction.

Here, i _th is a predetermined threshold current, and when the absolute value of the magnitude of the current i calculated in step S3 is equal to or less than the predetermined threshold current i _th , no current flows through the Peltier element 7. Like that.

Thereafter, the control unit 8 repeats the above operation, and when the control is finished, the process proceeds to step S8 and is finished.
As described above, according to the present invention, it is possible to provide a temperature adjustment method and system for reducing cell temperature variation in order to suppress variation in deterioration in cell units.

Subsequently, a second embodiment of the present invention will be described.
FIG. 7 is a block diagram showing a configuration of a temperature control system according to another embodiment of the present invention, and includes a second example of the temperature control system for implementing the present invention.

  The temperature control system shown in FIG. 7 includes cells 18, 19 and 20, a temperature measurement unit 21, Peltier elements 22 and 23, a control unit 24, and a DDC 25. As shown in FIG. 7, the block diagram of the second embodiment is almost the same as FIG. 2 which is the block diagram of the first embodiment, but the Peltier element between the cell 18 and the cell 19 is used. 22 is different in that a Peltier element 23 is arranged between the cell 19 and the cell 20 and three temperature measuring units 21 are arranged for each cell. The rest of the system configuration and the operation procedure of each part are the same as in FIG.

  FIG. 8 is a diagram showing an example of the arrangement of cells, Peltier elements, and thermistors in the system shown in FIG. The left side of FIG. 8 schematically shows the arrangement of cells, Peltier elements, and thermistors, and the right side shows a cross section thereof. The thermistor 28 is shown as an example of the temperature measurement unit 21 in FIG.

  As shown in FIG. 8, the arrangement of cells, Peltier elements, and thermistors in the system shown in FIG. 7 is substantially the same as the arrangement of cells, Peltier elements, and thermistors in the system shown in FIG. Two Peltier elements 27 are arranged between the three cells 26, and the thermistors 28 are arranged in a total of three locations for each cell. Other features are the same as in FIG.

FIG. 9 is a diagram showing the relationship between the cell temperature and the heat generation and heat absorption of the Peltier element in the system shown in FIG.
A Peltier element 22 is disposed in the gap between the cells 18 and 19, and a Peltier element 23 is disposed in the gap between the cells 19 and 20. In FIG. 9, the temperature measurement unit 21, the control unit 24, and the DDC 25 shown in FIG. 7 are omitted.

The temperature of the cell 18 is T ₃ , the temperature of the cell 19 is T ₄ , and the temperature of the cell 20 is T ₅ . In addition, the amount of heat generated from the Peltier element 22 to the cell 18 is Q ¹ _w , the amount of heat absorbed by the Peltier element 22 from the cell 19 is Q ¹ _c , and the current flowing through the Peltier element 22 is i ₁ . Further, the amount of heat generated from the Peltier element 23 to the cell 19 is Q ² _w , the amount of heat absorbed by the Peltier element 23 from the cell 20 is Q ² _c , and the current flowing through the Peltier element 23 is i ₂ . When the heat capacity of the cell 18 is C ₃ , the heat capacity of the cell 19 is C ₄ , the heat capacity of the cell 20 is C ₅ , and the temperature at the time of thermal equilibrium is T ^′ , the following three equations are established.

If the above two expressions are arranged with respect to T ^′ , the following expression is established.

Here, the thermoelectric powers of the Peltier elements 22 and 23 are α ₁ and α ₂ , the internal resistances of the Peltier elements 22 and 23 are R ₁ and R ₂ , respectively, and the thermal conductances of the Peltier elements 22 and 23 are K ₁ and K ₂ , respectively. Then, the following four expressions hold.

The magnitudes and directions of the currents i ₁ and i ₂ flowing in the Peltier elements 22 and 23 can be obtained by solving the formula 9 with respect to i ₁ and i ₂ using the formulas 10, 11, 12, and 13. As described above, the magnitudes and directions of the currents i ₁ and i ₂ flowing through the Peltier elements 22 and 23 are determined according to the temperature difference between the cells 18 and 19 and the temperature difference between the cells 19 and 20. be able to.

FIG. 10 is a flowchart executed to perform the control shown in FIG.
First, for example, when the engine of the automobile is started, the control unit 24 is started, and each circuit is turned on (step M1).

Subsequently, the temperature measurement unit 21 measures the temperature of each cell 18, 19, and 20 and transmits it to the control unit 24 (step M2). The control unit 24 that has received the temperature of each of the cells 18, 19, and 20 calculates the currents i ₁ and i ₂ that flow through the Peltier elements 22 and 23 by solving Equation 9, respectively (step M 3). Subsequently, control is performed so that the currents i ₁ and i ₂ flow through the Peltier elements 22 and 23, respectively (step M4).

Thereafter, the control unit 24 repeats the above operation, and when the control is to be ended, the process proceeds to step M5 and is ended.
As described above, even when three cells are arranged, it is possible to provide a temperature adjustment method and system for reducing cell temperature variation in order to suppress variation in cell-by-cell deterioration. In the temperature adjustment system according to the present invention, it is possible to carry out temperature adjustment with good accuracy in units of cells by controlling the direction and magnitude of the current flowing in the Peltier element according to the temperature difference between adjacent cells. Although it is possible, the temperature of the entire system can be made uniform as a result of temperature adjustment in units of cells at a plurality of locations.

  In this specification, in order to simplify the description, the case where two cells are arranged as the first embodiment and the case where three cells are arranged as the second embodiment have been described in detail. However, the temperature adjustment is not limited to this, and the temperature adjustment as described above may be performed by arranging four or more cells.

  In the present specification, a system and a method for performing temperature control by arranging Peltier elements between cells have been described. However, the configuration of the system is not limited to this, and the cell portion may be a module or a pack. By using the method and system described above, the temperature of each module or pack can be measured and the temperature can be adjusted between the modules or packs.

  As described above in detail, according to the present invention, it is possible to provide a temperature adjustment method and system for reducing cell temperature variation in order to suppress variation in cell-by-cell deterioration. As a result, the temperature difference between the cells is made constant, and the lifetime of the entire module and pack can be maximized. Moreover, since both heat absorption and heat generation can be used for temperature adjustment at a time, it is possible to effectively use energy for making the temperature difference constant.

1 cell 2 module 3 pack 4 cell 5 cell 6 temperature measurement unit 7 Peltier element 8 control unit 9 DDC
DESCRIPTION OF SYMBOLS 10 cell 11 Peltier device 12 Thermistor 13 Positive electrode 14 Negative electrode 15 A terminal 16 B terminal 17 Control board 18 Cell 19 Cell 20 Cell 21 Temperature measurement part 22 Peltier element 23 Peltier element 24 Control part 25 DDC
26 cells 27 Peltier elements 28 thermistors

Claims (7)

A first module having one or more cells;
A second module having one or more cells;
A temperature measuring unit disposed on the surface of each of the first module and the second module;
A Peltier element disposed between the first module and the second module;
A controller that obtains the temperatures of the first and second modules from the temperature measuring unit and controls a current flowing through the Peltier element;
Including
The control unit controls the direction and magnitude of the current passed through the Peltier element according to the difference between the temperature of the first module and the temperature of the second module.
A temperature control system characterized by that. The control unit controls the current not to flow through the Peltier element when the difference between the temperature of the first module and the temperature of the second module falls within a predetermined range.
The temperature control system according to claim 1. The control unit controls the direction and magnitude of the current flowing through the Peltier element by transmitting a signal to a DC / DC converter circuit.
The temperature control system according to claim 1 or 2, wherein Obtaining a temperature of a first module having one or more cells;
Obtaining a temperature of a second module having one or more cells;
The direction and magnitude of the current flowing in the Peltier element arranged between the first module and the second module are controlled according to the temperature difference between the first module and the second module. Steps,
including,
The temperature control method characterized by the above-mentioned. When the difference between the temperature of the first module and the temperature of the second module falls within a predetermined range, the method further includes a step of controlling the current not to flow through the Peltier element.
The temperature control method according to claim 4. Further comprising controlling the direction and magnitude of the current flowing through the Peltier element by transmitting a signal to a DC / DC converter circuit;
The temperature control method according to claim 4 or 5, wherein A plurality of modules having one or more cells;
A temperature measuring unit disposed on the surface of each of the plurality of modules;
A plurality of Peltier elements disposed between the plurality of adjacent modules;
A controller that obtains temperatures of the plurality of modules from the temperature measurement unit, and controls currents that flow through the plurality of Peltier elements;
Including
The control unit controls the direction and magnitude of the current flowing through the plurality of Peltier elements according to a temperature difference between the plurality of modules.
A temperature control system characterized by that.