Title of the invention: Battery pack cooling system for electric vehicles and cooling method of battery pack system for electric vehicles using the same
Technical field
[One]
The present invention relates to a battery pack cooling system for an electric vehicle and a cooling method using the same, and more particularly, a battery pack cooling system for an electric vehicle capable of preventing an increase in battery temperature during quick charging, and an electric vehicle using the same It relates to a method for cooling a battery pack system for use. This application is an application for claiming priority for Korean Patent Application No. 10-2018-0080099 filed on July 10, 2018, and all the contents disclosed in the specification and drawings of the application are incorporated herein by reference.
Background
[2]
In recent years, as the demand for portable electronic products such as laptops and portable phones increases rapidly, and the demand for electric carts, electric wheelchairs, and electric bicycles also increases, research on high-performance secondary batteries capable of repetitive charging and discharging has been actively conducted. Has become. In addition, as carbon energy is gradually depleted and interest in the environment is increasing in recent years, demand for electric vehicles (EV) such as PEV (Plug-in Electric Vehicle) and PHEV (Plug-in Hybrid Electric Vehicle) gradually increases worldwide. Are doing.
[3]
Accordingly, more interest and research are being focused on the battery pack, which is a key component of electric vehicles, and development of a rapid charging technology capable of rapidly charging batteries is urgently needed. In particular, for PEVs where there is no additional energy source, fast charging is a very important performance.
[4]
The process of charging the cell involves supplying current to the cell to accumulate charge and energy, and this process must be carefully controlled. In general, this is because excessive charging rates or charging voltages can permanently degrade the performance of the battery and ultimately cause complete failure or sudden failure such as leakage or explosion of highly corrosive chemicals.
[5]
As a unit of charge rate and discharge rate, "C", which is a C-rate, is used. For example, 1C refers to the charge/discharge rate at which the capacity of a fully charged battery is pulled out or filled within one hour, and also refers to the current density at that time. Recently, as the functions of electronic devices have been diversified, the amount of electric current used by the devices within a certain period of time has been greatly increased. Accordingly, the battery used as the energy source is also required to have higher performance. In the case of portable telephones, in the past, most of them required 1/2C, but in the future, these functions will be further strengthened to require a performance equivalent to 1C. Currently, notebook batteries and battery packs for electric vehicles require a similar charging slate and a much higher discharge slate.
[6]
In the automotive market, the demand for charging time is increasing, and a higher charging sheet rate is required to meet this. Therefore, it is preferable from the viewpoint of rapid charging that the charging slate is higher than 1C. However, in the case of charging an electric vehicle, if the battery is unconditionally charged with a strong voltage and current, the internal structure of the battery may be destroyed and the durability life and output may be drastically reduced. For example, during rapid charging with a high charging current density, Li-plating phenomenon becomes a problem because Li is precipitated without intercalation in the negative electrode. In addition, if the battery is continuously charged with a high current, high heat generation may be accompanied inside the battery unlike in a general charging process, and each electrode may form an overvoltage state due to the resistance of the battery.
[7]
In general, charging of a battery pack for an electric vehicle is controlled by a battery management system (BMS) provided in the battery pack. BMS needs to control fast charging in a short time by setting appropriate control parameters, and the temperature of the battery is the control variable most related to the durability life of the battery pack. Depending on the temperature of the battery, the current that can be charged may be limited, and the battery lifespan may vary. For example, the BMS detects the battery's state of charge (SOC) and temperature after charging starts, and charges the battery until the SOC reaches the target SOC. If the battery temperature is higher than the critical temperature, the battery is temporarily suspended and It can be configured to cool and charge the battery to a target SOC only when it is below the critical temperature.
[8]
As described above, when the battery temperature rises above the set critical temperature, charging must be stopped, and when the conventional cooling method is applied, if cooling is insufficient, a charging delay inevitably occurs. Therefore, in the case of rapid charging, a cooling method differentiated from the general charging process is also required.
[9]
Water-cooled and air-cooled cooling methods are widely known as general battery cooling methods.The battery pack for electric vehicles is generally cooled by air-cooled structure using air, and the battery pack is cooled by inhaling air from outside or inside the vehicle. It consists of a structure that discharges it to the outside of the vehicle after making it. However, there is a limit to cooling the battery pack using only air, and since air circulation is not smooth, especially when the vehicle is stopped, there is a limit to cooling the battery pack by effectively discharging the heat generated from the battery pack to the outside. There is.
[10]
The water-cooled cooling method is a technology that cools using a heat exchange medium (refrigerant) such as cooling water. A refrigerant conduit having a shape like a coil of an electric field plate is mounted to allow heat conduction with the outside of the battery, and the refrigerant is introduced into the refrigerant conduit to conduct heat. It is a technology to indirectly cool the battery by using. For example, Korean Patent Registration Nos. 10-1112442, 10-1205181, and 10-1833526 disclose a battery module having a water-cooled cooling device.
[11]
The water cooling method has superior cooling efficiency compared to the air cooling method. Therefore, it would be desirable if a more specialized cooling method and cooling system were implemented during rapid charging of a battery pack for an electric vehicle by using such a water cooling method.
Detailed description of the invention
Technical challenge
[12]
An object of the present invention is to provide a battery pack cooling system for an electric vehicle that can be utilized during rapid charging.
[13]
Another object of the present invention is to provide a cooling method of a battery pack system for an electric vehicle that can be utilized during rapid charging.
[14]
Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by examples of the present invention. In addition, it will be readily understood that the objects and advantages of the present invention can be realized by means and combinations thereof indicated in the claims.
Means of solving the task
[15]
In order to achieve the above object, the battery pack cooling system for an electric vehicle according to the present invention includes a battery pack including a plurality of batteries; A water cooling type cooling device including a refrigerant conduit mounted to conduct heat conduction with the outside of the battery, and indirectly cooling the battery by using heat conduction by introducing a refrigerant into the refrigerant conduit; It is installed between an inlet-side refrigerant conduit through which the refrigerant flows into the battery pack among the refrigerant conduit of the water-cooled cooling device and an outlet-side refrigerant conduit that discharges the refrigerant cooled from the battery pack to the outside of the battery pack, and the inlet-side refrigerant A thermoelectric element module having a heat absorbing surface facing the conduit and a heating surface facing the outlet side refrigerant conduit; A current sensor that detects the amount of charging current supplied to the battery pack; And determining a charging slate (C-rate) from the magnitude of the charging current, and driving the thermoelectric device module when the charging slate is higher than a preset threshold to cause a temperature difference between the heat absorbing surface and the heating surface. And a configured control unit.
[16]
Preferably, the heat absorbing surface is brought into contact with the inlet-side refrigerant conduit and the heating surface is brought into contact with the outlet-side refrigerant conduit so that heat exchange occurs between the inlet-side refrigerant conduit and the outlet-side refrigerant conduit through the thermoelectric element module.
[17]
The battery pack further includes a pack case, further comprising a cooling member configured to cool the battery by flowing the refrigerant into the pack case, and a continuous flow path is formed in the cooling member, and Both ends are connected to a refrigerant inlet through which the refrigerant flows into the battery pack and a refrigerant outlet through which refrigerant that has cooled the battery pack is discharged to the outside of the battery pack, and the inlet side refrigerant conduit is connected to the refrigerant inlet, and the The outlet side refrigerant conduit is connected to the refrigerant outlet.
[18]
Preferably, the battery pack cooling system for an electric vehicle further comprises a temperature sensor installed in the battery pack to detect a temperature of the battery pack, and the control unit includes a temperature of the battery pack using the temperature sensor. It is configured to determine a time change rate, and drive the thermoelectric device module when the time change rate is greater than or equal to a preset value and the charging sill rate is greater than or equal to a preset threshold.
[19]
The charging current may be supplied from an external charging device for the battery pack, and the current sensor may be installed on a charging line connecting the battery pack and an external charging device.
[20]
Power for driving the thermoelectric device module is supplied from an external power supply device, the battery pack cooling system for an electric vehicle further comprises a switch connected between the external power supply device and the thermoelectric device module, the control unit, the It may be configured to turn on a switch to drive the thermoelectric device module.
[21]
In order to achieve the above other object, the cooling method of the battery pack system for an electric vehicle according to the present invention includes a battery pack including a plurality of batteries, and a refrigerant introduced through a refrigerant conduit mounted to enable heat conduction with the outside of the battery. It is a cooling method of a battery pack system for an electric vehicle including a water-cooled cooling device that indirectly cools the battery. This method includes (a) between an inlet side refrigerant conduit through which the refrigerant flows into the battery pack among the refrigerant conduit of the water cooling system and an outlet side refrigerant conduit through which the refrigerant cooled the battery pack is discharged to the outside of the battery pack. Providing a thermoelectric device module, wherein a heat absorbing surface and a heating surface of the thermoelectric device module face each of the inlet-side refrigerant conduit and the outlet-side refrigerant conduit; (b) determining a charging slate by measuring the amount of charging current flowing through a charging line connecting the battery pack and an external charging device; And (c) when the charging slate is higher than a preset threshold, driving the thermoelectric device module to cause a temperature difference between the heat absorbing surface and the heating surface of the thermoelectric device module, thereby lowering the temperature of the refrigerant at the heat absorbing surface. It includes; supplying to the battery pack side.
[22]
Preferably, the step (a) comprises contacting the heat absorbing surface with the inlet side refrigerant conduit so that heat exchange is performed between the inlet side refrigerant conduit and the outlet side refrigerant conduit through the thermoelectric element module, and the heating surface is brought into the outlet. Contacting the side refrigerant conduit.
[23]
Preferably, in step (c), the thermoelectric device module is driven when the charging slate is fast charging of 2C or higher.
[24]
Preferably, the step (c) comprises the steps of measuring the temperature of the battery pack; And driving the thermoelectric device module when the rate of change of time with respect to the temperature of the battery pack is greater than or equal to a preset value and the charge slate is greater than or equal to a preset threshold.
[25]
In step (c), it is preferable to supply power from an external power supply device to drive the thermoelectric device module.
Effects of the Invention
[26]
Rapid charging requires a cooling method that is differentiated from the general charging process. According to the present invention, since the thermoelectric device module is operated during rapid charging to cool the refrigerant and used for cooling the battery pack, it is possible to effectively remove a large amount of heat generated from the battery pack during rapid charging.
[27]
Accordingly, in the case of insufficient cooling in the conventional battery pack, a problem in which a charging delay occurs can be improved, and a problem in which the battery pack is deteriorated due to heat accumulation can be improved. By improving battery pack deterioration, not only can the life of the battery pack be prolonged, but also ignition or explosion can be fundamentally blocked.
Brief description of the drawing
[28]
The following drawings attached to the present specification illustrate preferred embodiments of the present invention, and serve to further understand the technical idea of ​​the present invention together with the detailed description of the present invention to be described later, so the present invention is described in such drawings. It is limited to and should not be interpreted.
[29]
1 is a schematic diagram of a battery pack cooling system for an electric vehicle according to an embodiment of the present invention.
[30]
FIG. 2 shows a part of a battery pack system that may be included in the battery pack cooling system for an electric vehicle of FIG. 1.
[31]
3 is a schematic diagram of an exemplary cooling member that may be included in the battery pack system of FIG. 2.
[32]
FIG. 4 schematically shows a connection relationship between a thermoelectric device module and a refrigerant conduit that may be included in the battery pack cooling system for an electric vehicle of FIG. 1.
[33]
5 is a schematic diagram of a thermoelectric device module that can be included in the battery pack cooling system for an electric vehicle of FIG. 1.
[34]
6 is a graph that simulates the cooling effect of the cooling method of the battery pack system for an electric vehicle according to an embodiment of the present invention.
Mode for carrying out the invention
[35]
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the embodiments according to the present invention may be modified in various different forms, and the scope of the present invention should not be construed as being limited to the following examples. The embodiments of the present invention are provided to more completely describe the present invention to those of ordinary skill in the art.
[36]
The terms or words used in the specification and claims should not be construed as being limited to their usual or dictionary meanings, and the inventor may appropriately define the concept of terms in order to describe his own invention in the best way. It should be interpreted as a meaning and concept consistent with the technical idea of ​​the present invention based on the principle that there is.
[37]
Therefore, the embodiments described in the present specification and the configurations shown in the drawings are only the most preferred embodiment of the present invention, and do not represent all the technical spirit of the present invention, and thus various It should be understood that there may be equivalents and variations.
[38]
1 is a schematic diagram of a battery pack cooling system for an electric vehicle according to an embodiment of the present invention.
[39]
Referring to FIG. 1, a battery pack cooling system 100 for an electric vehicle according to an embodiment of the present invention applies a thermoelectric module (TEM) 70 to a battery pack system 10.
[40]
In FIG. 1, reference numeral 200 denotes an electric vehicle charging station. For example, the battery pack 1 may be charged at the electric vehicle charging station 200 by connecting the cable 230 of the electric vehicle charging station 200 to the connector 110 of the electric vehicle. In this case, the electric vehicle charging station 200 may include an external charging device 210 and an external power supply device 220.
[41]
The battery pack system 10 includes a battery pack 1 and a water-cooled cooling device 20.
[42]
The battery pack 1 includes a plurality of batteries 1'.
[43]
The water-cooled cooling device 20 indirectly cools the battery 1 ′ by introducing a refrigerant through a refrigerant conduit 30 mounted to allow heat conduction to the outside of the battery 1 ′. In the drawing, the dotted arrow indicates the flow direction of the refrigerant. The water-cooled cooling device 20 may further include a heat exchanger (not shown) for heat exchange between the refrigerant conduit 30.
[44]
The battery pack cooling system 100 for an electric vehicle may be used together with air-cooled cooling performed in a conventional electric vehicle. For example, an internal air cooling method in which indoor air (indoor air supplied to the room from an air conditioner) is sucked through a cooling fan at a predetermined indoor location such as a package tray, passed through the battery pack 1, and then discharged through the trunk room. Can be used together.
[45]
FIG. 2 shows a part of a battery pack system that may be included in the battery pack cooling system for an electric vehicle of FIG. 1. 3 is a schematic diagram of an exemplary cooling member that may be included in the battery pack system of FIG. 2. FIG. 4 schematically shows a connection relationship between a thermoelectric device module and a refrigerant conduit that may be included in the battery pack cooling system for an electric vehicle of FIG. 1.
[46]
First of all, referring to FIG. 2, the battery pack 1 of the battery pack system 10 includes a plurality of batteries 1 ′ and a pack case 2. It has a structure in which the battery 1'can be cooled by flowing a refrigerant inside or outside the pack case 2 or through the pack case 2 itself.
[47]
For example, a cooling member 3 as shown in FIG. 3 may be provided inside the pack case 2. The cooling member 3 may be made of a metal plate 4, and the remaining portion 6 may be sealed or formed in a solid structure with a continuous flow path 5 formed on the inner surface thereof. Both ends of the flow path (5) are a refrigerant inlet (Inlet, 40) through which refrigerant flows into the battery pack (1) and a refrigerant outlet (outlet) through which refrigerant that has cooled down the battery pack (1) is discharged to the outside of the battery pack (1). ). In the drawing, the dotted arrows indicate the flow direction of the refrigerant.
[48]
Referring back to FIG. 1, the refrigerant conduit 30 is connected to the refrigerant inlet 40 and the refrigerant outlet 50 from the outside of the battery pack 1 with respect to the cooling member 3 of the battery pack system 10. The refrigerant conduit 30 is connected to the refrigerant inlet 40 and is connected to the inlet side refrigerant conduit 42 and the refrigerant outlet 50, which is a part close to the refrigerant inlet 40, and is connected to the refrigerant outlet 50. It includes an outlet side refrigerant conduit 52. The inlet side refrigerant conduit 42 and the outlet side refrigerant conduit 52 are also shown in the battery pack system 10 of FIG. 2.
[49]
When there is a temperature difference between both ends of a material in a solid state, a difference in the concentration of carriers (electrons or holes) having a heat dependence occurs, and this appears as an electrical phenomenon called thermoelectric power, that is, a thermoelectric phenomenon. As such, the thermoelectric phenomenon refers to a reversible and direct energy conversion between a temperature difference and a voltage. These thermoelectric phenomena can be classified into thermoelectric power generation that produces electrical energy, and thermoelectric cooling/heating that causes a temperature difference at both ends by applying a current on the contrary.
[50]
In the present invention, in order to cause a temperature difference at both ends of the thermoelectric device module 70 to cool the thermoelectric device, power is supplied to the thermoelectric device module 70 from an external power supply device. When an electromotive voltage is formed on both sides of the thermoelectric element module 70 through power supply from an external power supply device, one side is cooled by heat absorption and the other side is heated by heat dissipation. Accordingly, when a current is applied by supply of driving power, one side of the thermoelectric element module 70 becomes a heat absorbing surface and the other side becomes a heat generating surface.
[51]
As shown in FIG. 1, the thermoelectric device module 70 is particularly installed to be located between the inlet side refrigerant conduit 42 and the outlet side refrigerant conduit 52 of the water-cooled cooling device 20, and this is shown in FIG. Shown in more detail.
[52]
As shown in Figure 4, the inlet side refrigerant conduit 42 or the inlet side refrigerant conduit support member 43 surrounding the inlet side refrigerant conduit 42 and the outlet side refrigerant conduit 52 or the outlet side refrigerant conduit 52. The thermoelectric element module 70 is attached between the surface of the outlet side refrigerant conduit support member 53 surrounding the). The direction of current application through the supply of driving power is the heat absorbing surface of the thermoelectric element module 70 on the inlet side refrigerant conduit 42 or the inlet side refrigerant conduit support member 43 surrounding the inlet side refrigerant conduit 42 (70a) is formed, and the side attached to the outlet side refrigerant conduit 52 or the outlet side refrigerant conduit support member 53 surface surrounding the outlet side refrigerant conduit 52 forms the heating surface 70b. will be. When current is applied in this way, the thermoelectric device module 70 absorbs heat from the inlet side refrigerant conduit 42 and radiates heat toward the outlet side refrigerant conduit 52, so that heat flow as indicated by arrows in FIG. 4 is generated. In other words, the heat absorbing surface 70a is attached to the inlet side refrigerant conduit 42 so that heat exchange is performed between the inlet side refrigerant conduit 42 and the outlet side refrigerant conduit 52 through the thermoelectric element module 70. The heating surface (70b) is to be attached to the outlet side refrigerant conduit (52) side. Here, the inlet side refrigerant conduit support member 43 and the outlet side refrigerant conduit support member 53 surround the inlet side refrigerant conduit 42 and the outlet side refrigerant conduit 52, respectively, and serve to structurally support them in the vehicle. It can be done and is an element that can be omitted.
[53]
As described above, in the present invention, the heat absorbing surface 70a and the heating surface 70b of the thermoelectric element module 70 are provided to face the inlet side refrigerant conduit 42 and the outlet side refrigerant conduit 52, respectively. The heat absorbing surface 70a is brought into contact with the inlet-side refrigerant conduit 42 so that heat exchange occurs between the inlet-side refrigerant conduit 42 and the outlet-side refrigerant conduit 52 through the thermoelectric element module 70, and the heating surface 70b ) Is preferably in contact with the outlet side refrigerant conduit 52. Contact includes both direct contact or indirect contact through the support members 43 and 53.
[54]
In general, a thermoelectric device module may be a basic unit of a pair of pn thermoelectric devices comprising a p-type thermoelectric device for moving heat energy by moving a hole and an n-type thermoelectric device for transferring heat energy by moving electrons. In addition, such a thermoelectric module may include an electrode connecting the p-type thermoelectric element and the n-type thermoelectric element. In addition, the thermoelectric module may be disposed outside the thermoelectric module to electrically insulate components such as electrodes from the outside, and may have a substrate to protect the thermoelectric module from external physical or chemical elements.
[55]
5 is a schematic diagram of a thermoelectric device module that can be included in the battery pack cooling system for an electric vehicle of FIG. 1.
[56]
Referring to FIG. 5, the thermoelectric device module 70 includes a substrate 75, an electrode 80, and a thermoelectric device 85.
[57]
The substrate 75 is formed in a plate shape and is disposed outside the thermoelectric device module 70 to protect various components of the thermoelectric device module 70 such as the thermoelectric device 85, and between the thermoelectric device module 70 and the outside. Electrical insulation can be maintained. The substrate 75 may be an alumina substrate. The substrate 75 is provided as a pair of an upper substrate 76 and a lower substrate 77 facing each other.
[58]
The electrode 80 has electrical conductivity so that a current can flow. In addition, the electrode 80 may be provided on the substrate 75. In particular, the electrode 80 is configured to be exposed to at least one surface of the substrate 75 so that the thermoelectric element 85 is mounted. In particular, at least two thermoelectric elements 85 may be mounted on the electrode 80, and a path through which a current may flow between the two thermoelectric elements 85 is provided. These electrodes 80 may be provided on the lower surface of the upper substrate 76 and on the upper surface of the lower substrate 77 by a method such as deposition, sputtering, direct compression, printing, and a plurality of thermoelectric elements 85 between them. Is disposed to configure the thermoelectric device module 70. A DBC (Direct Bonded Copper) type substrate in which the electrode 80 is formed directly on the substrate 75 may also be used. The electrode 80 is preferably formed of a metal, for example, at least one selected from the group including Cu, Au, Ag, Ni, Al, Cr, Ru, Re, Pb, Sn, In, and Zn. It may be formed of a metal or an alloy containing at least two of these metals. Among the electrodes 80, the upper electrode 81 formed on the upper substrate 76 connects them to each other at the top of the thermoelectric element 85, and the lower electrode 82 formed on the lower substrate 77 among the electrodes 80 The thermoelectric element 85 connects them to each other at the bottom.
[59]
The thermoelectric element 85 may be formed of a thermoelectric material, that is, a thermoelectric semiconductor. The thermoelectric semiconductor may include various types of thermoelectric materials such as chalcogenide, skutterudite, silicide, clathrate, and half heusler. have. For example, a thermoelectric material such as a BiTe-based material or a PbTe-based material may be appropriately doped and used. Various types of thermoelectric semiconductors known at the time of filing of the present invention may be used as a material of the thermoelectric element 85.
[60]
The thermoelectric element 85 may be configured in a form in which a thermoelectric material is sintered in a bulk form. In the conventional thermoelectric module, the thermoelectric element is mainly composed of an electrode through a vapor deposition method. However, in the thermoelectric device module 70 to be described as an example, the thermoelectric device 85 is not formed in a form deposited on the electrode 80, but may be first sintered into a bulk form. And, after that, the bulk type thermoelectric element 850 may be bonded to the electrode 80. Further, although not shown in the drawings, a buffer layer (not shown) for improving adhesion between the electrode 80 and the thermoelectric element 85 may be further included.
[61]
First, the thermoelectric device 85 may be manufactured in a bulk form. In this case, the bulk-type thermoelectric element 85 includes the steps of forming a mixture by mixing each raw material of the thermoelectric element 85, forming a composite by heat treating the mixed raw material, and sintering the composite. It can be manufactured by a manufacturing method. The thermoelectric material sintered in the sintering step may be formed in a bulk form. Next, the thermoelectric material sintered in a bulk form as described above may be processed into a size and/or shape suitable for application to the thermoelectric element module 70. For example, a thermoelectric material sintered into a cylindrical bulk shape may be cut into a hexahedral bulk shape having a smaller size. That is, it may be a structure formed by pulverizing an ingot, which is a thermoelectric material, followed by a micronization ball-mill process, and then cutting the sintered structure. In addition, the thermoelectric material processed into a smaller bulk shape as described above may be bonded to the electrode 80 of the substrate 75 as the thermoelectric element 85. Here, the bulk type thermoelectric element 85 and the electrode 80 may be bonded by various methods such as heat treatment such as sintering or soldering, and the present invention is not limited to a specific bonding method.
[62]
As described above, according to the configuration in which the thermoelectric element 85 is sintered in a bulk form and then bonded to the electrode 80, since the thermoelectric element 85 has a dense structure through sintering, a conventional thermoelectric element, especially in a vapor deposition form, Compared to the conventional thermoelectric device configured, thermoelectric performance can be significantly improved.
[63]
The thermoelectric element 85 may be referred to as a thermoelectric leg, and may include an n-type thermoelectric element 86 and a p-type thermoelectric element 87. Here, the n-type thermoelectric element 86 may be configured in a form in which an n-type thermoelectric material is sintered into a bulk form. In addition, the p-type thermoelectric element 87 may be configured in a form in which a p-type thermoelectric material is sintered in a bulk form. As the n-type thermoelectric material and the p-type thermoelectric material, various materials known at the time of filing of the present invention may be employed, and thus detailed descriptions thereof will be omitted.
[64]
In the thermoelectric element 85, an n-type thermoelectric element 86 and a p-type thermoelectric element 87 may form a pair to form one basic unit. In addition, two or more n-type thermoelectric elements 86 and p-type thermoelectric elements 87 may be provided to form a plurality of pairs. In addition, the n-type thermoelectric element 86 and the p-type thermoelectric element 87 are alternately arranged to form a plurality of n-type thermoelectric element 86-p-type thermoelectric element 87 pairs.
[65]
The n-type thermoelectric element 86 and the p-type thermoelectric element 87 may be electrically connected to each other through an electrode 80. For example, based on one electrode 80, the n-type thermoelectric element 86 may be bonded to one end of the electrode 80, and the p-type thermoelectric element 87 may be bonded to the other end of the electrode 80. . The shapes of the upper electrode 81 and the lower electrode 82 formed on the upper and lower substrates 76 and 77, respectively, must be considered so that they can be connected in parallel thermally and in series electrically. The thermoelectric elements 85 are connected in series, and lead wires 90 are provided at both ends of the thermoelectric elements 85 connected in series so that electricity can be supplied from the outside.
[66]
The amount and direction of heat absorption and heat generation can be adjusted according to the magnitude and direction of the current applied to the thermoelectric device module 70. The electrode 80 bonded to the n-type thermoelectric element 86 generates heat on the side where the current flows in and absorbs heat on the opposite side, and the p-type thermoelectric element 87 generates heat and absorbs heat in reverse. The thermoelectric element module 70 has no mechanically actuated part, and its installation position or direction does not affect its operation, so it is very suitable for introduction into a water-cooled cooling device (20 in FIG. 1). In addition, since the thermoelectric device module 70 can be manufactured in a thin shape, it can be inserted into the space between the refrigerant conduit (30 in Fig. 1) and can provide high cooling performance without increasing the size or weight of the water-cooled cooling device. have.
[67]
Referring to FIGS. 4 and 5 together, in an embodiment of the present invention, a member ( While being attached to the surface 43, the heating surface 70b of the thermoelectric element module 70 is attached to the outlet-side refrigerant conduit 52 or the outlet-side refrigerant conduit 52 to the surrounding member 53 surface. For example, the lower substrate 77 side is the heat absorbing surface 70a and the upper substrate 76 side is the heating surface 70b. In this way, the direction of the current applied to the lead wire 90 may be determined. Also in Figure 5, the flow of heat accordingly is indicated by arrows.
[68]
The use of the battery pack cooling system 100 as described above corresponds to a cooling method of the battery pack system 10. Referring again to FIG. 1, components of the battery pack cooling system 100 and use of the battery pack cooling system 100 will be described in more detail.
[69]
The battery pack cooling system 100 further includes a current sensor 92, a temperature sensor 93, a switch 94, and a control unit 95.
[70]
The current sensor 92 detects the magnitude of the charging current supplied to the battery pack 1. The charging current is supplied from the external charging device 210 of the battery pack 1, for example, the external charging device 210 may be included in the charging station 200 of the electric vehicle. The current sensor 92 may be installed on a charging line 92 ′ connecting the battery pack 1 and the external charging device 210.
[71]
The temperature sensor 93 is installed in the battery pack 1 to detect the temperature of the battery pack 1. The temperature sensor 93 is, for example, a thermocouple.
[72]
Power for driving the thermoelectric element module 70 is supplied from an external power supply device 220, for example, the external power supply device 220 may be included in the charging station 200 of the electric vehicle. The switch 94 is connected between the external power supply device 220 and the thermoelectric device module 70 and controls the connection between the external power supply device 220 and the thermoelectric device module 70. For example, the switch 94 may be installed on a power supply line 94 ′ connecting the external power supply device 220 and the thermoelectric device module 70.
[73]
The control unit 95 is connected to the current sensor 92, the temperature sensor 93 and the switch 94, acquires information from the current sensor 92 and the temperature sensor 93, and controls the operation of the switch 94 In addition to executing various calculations for, the current sensor 92, the temperature sensor 93, and the switch 94 are controlled by outputting a control signal. The control unit 95 may be a BMS.
[74]
In particular, the control unit 95 determines the charging slate from the magnitude of the charging current. When the determined charging slate is greater than or equal to a preset threshold, the thermoelectric device module 70 is driven to cause a temperature difference between the heat absorbing surface 70a and the heating surface 70b. In this embodiment, when the control unit 95 turns on the switch 94, the thermoelectric device module 70 may be driven. Also, the control unit 95 may determine a rate of change over time with respect to the temperature of the battery pack 1 using the temperature sensor 93. It may be configured to drive the thermoelectric element module 70 when the time change rate is greater than or equal to a preset value and the charging sill rate is greater than or equal to a preset threshold.
[75]
The cooling method of the battery pack system 10 using the battery pack cooling system 100 may be performed as follows.
[76]
The inlet side refrigerant conduit 42 of the refrigerant conduit 30 of the water-cooled cooling device 20 flows into the battery pack 1, and the refrigerant that has cooled the battery pack 1 is discharged to the outside of the battery pack 1 A thermoelectric element module 70 is provided between the outlet side refrigerant conduit 52, wherein the heat absorbing surface 70a and the heating surface 70b of the thermoelectric element module 70 are respectively inlet side refrigerant conduit 42 and outlet side refrigerant. It is provided so as to face the conduit 52.
[77]
Using the current sensor 92, the amount of charging current flowing through the charging line 92' connecting the battery pack 1 and the external charging device 210 is measured, and the control unit 95 determines the charging slate. do. When the charging slate is more than a preset threshold, the control unit 95 drives the thermoelectric device module 70 to cause a temperature difference between the heat absorbing surface 70a and the heating surface 70b of the thermoelectric device module 70, The temperature of the refrigerant is lowered on the heat absorbing surface 70a and is supplied to the battery pack 1 side.
[78]
On the other hand, depending on the configuration of the control unit 95, by measuring the temperature of the battery pack 1 using the temperature sensor 93, the time change rate with respect to the temperature of the battery pack 1 is more than a preset value and the charging The thermoelectric device module 70 may be driven when all conditions in which the sill rate is equal to or greater than a preset threshold are satisfied. When determining whether the thermoelectric device module 70 is driven by considering the time change rate with respect to the temperature of the battery pack 1 rather than simply determining the charging plate rate only, the charging plate rate is less than a preset threshold, but the battery pack 1 ), even if the temperature of the battery pack 1 rapidly increases due to insufficient cooling, the thermoelectric device module 70 can be driven, thereby preventing an increase in the temperature of the battery pack 1.
[79]
When the thermoelectric element module 70 is operated, the heat absorbing surface 70a of the thermoelectric element module 70 absorbs heat from the inlet side refrigerant conduit 42, so that the temperature of the inlet side refrigerant passing through the inlet side refrigerant conduit 42 can be lowered. have. As described above, the first feature of the present invention is to increase cooling performance by applying the thermoelectric device module 70 to lower the temperature of a refrigerant such as cooling water to be supplied to the battery pack 1.
[80]
When the thermoelectric element module 70 is operated, the heat absorbing surface 70a of the thermoelectric element module 70 lowers the inlet-side refrigerant temperature, while the heating surface 70b of the thermoelectric element module 70 is an outlet side refrigerant conduit 52 or an outlet. Heat is radiated toward the surface of the member 53 surrounding the side refrigerant conduit 52. The refrigerant passing through the outlet side refrigerant conduit 52 moves with heat generated from the heating surface 70b of the thermoelectric element module 70. The second feature is that heat is not naturally radiated or accumulated on the heating surface of the thermoelectric element module 70, but heat is removed using the outlet side refrigerant so that the temperature of the heating surface is not increased.
[81]
The third feature is that the thermoelectric device module 70 operates only during rapid charging, such as when the charging slate is equal to or greater than a preset threshold. Since the thermoelectric device module 70 requires power consumption to produce a temperature difference, it is not operated in a general charging process, but is operated only during rapid charging.
[82]
In addition, the fourth feature is that power required to drive the thermoelectric device module 70 is solved by using a separate external power when charging the battery pack 1. Power for driving the thermoelectric element module 70 is supplied from an external power supply device 220, for example, the external power supply device 220 may be included in the charging station 200 of the electric vehicle.
[83]
The time it takes to rapidly charge the battery in an electric vehicle currently being developed by an automobile manufacturer is about 30 minutes to charge from 5% to 80% SOC. It means that the filling slate is less than about 2C. Compared to the conventional gasoline or diesel fueling time of about 5 minutes in general engine vehicles, electric vehicles take a considerable amount of time even if they are rapidly charged. Refueling and charging are in common in that they charge the driving energy of the vehicle, and the refueling time and charging time of the vehicle during long-distance driving can be seen as important considerations in terms of vehicle marketability.
[84]
To shorten the charging time, it would be better to have a high charging slate, but the charging slate should be determined in consideration of the type and characteristics of the battery. For example, a battery for PEV may have a charging slate of about 1.5C. As another example, the battery for PHEV may have an initial charge rate of 3C. Depending on the battery specification that requires a faster charging rate and a discharge rate, the initial charging rate can be further increased, for example, it can be increased to 5C. Such charging slate may be limited not only by the type of battery but also by the maximum current of the motor used in an actual vehicle. In the present invention, the rapid charging is assumed to indicate a charge slate of 1C or more, preferably 2C or more.
[85]
In the case of the present invention, the thermoelectric device module 70 is driven through external power only during rapid charging, and the inlet side refrigerant is lowered before entering the battery pack 1 by the operated thermoelectric device module 70. Because it is cooled by temperature, the battery cooling efficiency during rapid charging increases. The outlet side refrigerant cools the heating surface 70b of the thermoelectric device module 70 so that heat does not accumulate on the heating surface 70b of the thermoelectric device module 70 and is maintained at a low temperature.
[86]
As described above, in the present invention, in the present invention, the thermoelectric device module 70 is configured such that appropriate heat exchange is performed between the inlet side refrigerant conduit 42 and the outlet side refrigerant conduit 52, through which the battery pack 1 is cooled. Cooling performance can be improved by lowering the temperature of the refrigerant and supplying it to the battery pack 1. The thermoelectric device module 70 is designed to operate with external power that may be supplied from the charging station of the electric vehicle during rapid charging, thereby solving a source of power required when the thermoelectric device module 70 is operated.
[87]
The present invention operates the thermoelectric device module 70 by supplying external power to the thermoelectric device module 70 during rapid charging as described above, so that even if the temperature of the battery pack 1 increases during rapid charging, the temperature is further lowered. It can be used to effectively cool through the supply of refrigerant. That is, external power that can be supplied from the charging station of the electric vehicle is supplied to the thermoelectric elements 85 of the thermoelectric element module 70 through the lead wire 90 so that the heat absorbing surface 70a and the heating surface 70b Will constitute. In particular, the thermoelectric device module 70 operates only during rapid charging, thereby responding to cooling during rapid charging. Therefore, heat generated during rapid charging of the battery pack for an electric vehicle can be effectively released to the outside, thereby suppressing deterioration of the battery pack.
[88]
On the other hand, if the battery pack temperature rise range according to the charging slate is known, the temperature of the refrigerant to be supplied can be known when the battery pack temperature to be properly maintained is determined. Accordingly, it is possible to determine conditions such as the type of thermoelectric element required for this, and the amount of current to be supplied for an appropriate temperature difference between the heat absorbing surface/heating surface. In addition, as to how to implement the actual thermoelectric element and the shape of the cooling conduit, it is possible to change as much as possible within the range of ordinary capabilities of those skilled in the art.
[89]
6 is a graph that simulates the cooling effect of the cooling method of the battery pack system for an electric vehicle according to an embodiment of the present invention. In the graph, the horizontal axis is time (s) and the vertical axis is the maximum battery temperature (℃).
[90]
6 is obtained by assuming a case of rapid charging at 2C from 5% SOC to 95%. Among the three-dimensional, two-dimensional, one-dimensional and zero-dimensional simulation methods, "Lumped model calculation", a zero-dimensional simulation method, was used. Since the temperature changes according to the charging time, "Transient analysis" with time dependence was used instead of "Steady analysis" without time dependence.
[91]
It is assumed that the initial battery temperature is 50 °C and the outside temperature is 50 °C. The initial battery temperature and outside temperature conditions can be changed as much as possible according to the required use conditions. The maximum allowable temperature of the battery (for example, the critical temperature allowing charging in BMS) was 60°C. The maximum allowable temperature condition for a battery depends on the type of battery. In this experimental example, it was set to 60°C, which is normally required for a battery having a three-component NCM (nickel, cobalt, manganese) positive electrode material. It is advantageous that the total thermal resistance from the battery to the refrigerant is small. In this experimental example, it was calculated on the assumption that it was 2.0 K/W, which is a value that is generally preferred in the battery specifications for electric vehicles.
[92]
According to the present invention, by driving the thermoelectric device module, the temperature of the cooling water at the inlet side can be reduced to below the outside temperature, for example, to 10°C (Example 1 of the present invention). This case, the case where the inlet side cooling water temperature is 30°C (Comparative Example 1) and the case where the inlet side cooling water temperature is the same as the outside temperature of 50°C (Comparative Example 2) were selected and compared together.
[93]
As shown in FIG. 6, the battery temperature increases with the passage of (charging) time. The maximum battery temperature was changed to 55.2 °C, 65.7 °C, and 76.8 °C after about 1600 seconds as the inlet cooling water temperature changed to 10 °C, 30 °C, and 50 °C.
[94]
Therefore, as in Example 1 of the present invention, if the inlet cooling water temperature can be lowered to 10 °C, it is possible to maintain the maximum battery temperature below 60 °C during charging. In Comparative Examples 1 and 2, the maximum battery temperature exceeded 60°C.
[95]
BMS detects the battery SOC and temperature after charging starts and charges until the SOC reaches the target SOC, but if the battery temperature is higher than the critical temperature, the charging is temporarily suspended to cool the battery, and only in the state below the critical temperature. When the battery is configured to be charged to the target SOC, if the maximum battery temperature is maintained at 60° C. or lower as in the present invention, charging may be completed in a short time without interruption of charging. However, in Comparative Examples 1 and 2, in which the cooling water temperature is not lowered to the same extent as in the present invention, the maximum temperature of the battery exceeds 60° C., and thus charging will take a long time due to the need to suspend charging.
[96]
As such, the present invention relates to a cooling system for cooling a battery pack including a plurality of batteries and a cooling method using the same, wherein the cooling system includes a refrigerant conduit through which a refrigerant flows and a thermoelectric element module outside the refrigerant conduit. The heat absorbing surface of the thermoelectric device module may be attached to the inlet side refrigerant conduit side, and the heating surface may be attached to the outlet side refrigerant conduit side. The thermoelectric device module is operated with external power supplied when charging at a charging station (charging station) of the electric vehicle for the electric vehicle in which the battery pack is mounted. Since the cooled refrigerant cools the battery pack by the thermoelectric device module, cooling performance against excessive heat generation of the battery pack during rapid charging may be improved.
[97]
As described above, although the present invention has been described by limited embodiments and drawings, the present invention is not limited thereto, and the technical idea of ​​the present invention and the following by those of ordinary skill in the art to which the present invention pertains. It goes without saying that various modifications and variations are possible within the equivalent range of the claims to be described.
Claims
[Claim 1]
A battery pack including a plurality of batteries; A water cooling type cooling device including a refrigerant conduit mounted to conduct heat conduction with the outside of the battery, and indirectly cooling the battery by using heat conduction by introducing a refrigerant into the refrigerant conduit; It is installed between an inlet-side refrigerant conduit through which the refrigerant flows into the battery pack among the refrigerant conduit of the water-cooled cooling device and an outlet-side refrigerant conduit that discharges the refrigerant cooled from the battery pack to the outside of the battery pack, and the inlet-side refrigerant A thermoelectric element module having a heat absorbing surface facing the conduit and a heating surface facing the outlet side refrigerant conduit; A current sensor that detects the amount of charging current supplied to the battery pack; And determining a charging slate (C-rate) from the magnitude of the charging current, and driving the thermoelectric device module when the charging slate is above a preset threshold to cause a temperature difference between the heat absorbing surface and the heating surface. A battery pack cooling system for an electric vehicle comprising a configured control unit.
[Claim 2]
The method of claim 1, wherein the heat absorbing surface is brought into contact with the inlet-side refrigerant conduit so that heat exchange occurs between the inlet-side refrigerant conduit and the outlet-side refrigerant conduit through the thermoelectric element module, and the heating surface is connected to the outlet-side refrigerant conduit. Electric vehicle battery pack cooling system, characterized in that in contact.
[Claim 3]
The method of claim 1, wherein the battery pack further comprises a pack case, further comprising a cooling member configured to cool the battery by flowing the refrigerant inside the pack case, and a continuous flow path is formed in the cooling member. And both ends of the flow path are connected to a refrigerant inlet through which the refrigerant flows into the battery pack and a refrigerant outlet through which the refrigerant that has cooled the battery pack is discharged to the outside of the battery pack, and the inlet-side refrigerant conduit is connected to the refrigerant A battery pack cooling system for an electric vehicle, characterized in that it is connected to an inlet, and the outlet-side refrigerant conduit is connected to the refrigerant outlet.
[Claim 4]
The battery pack cooling system of claim 1, further comprising a temperature sensor installed in the battery pack to detect a temperature of the battery pack, and the control unit comprises: the battery pack using the temperature sensor. A battery pack cooling system for an electric vehicle, characterized in that it is configured to determine a time change rate with respect to the temperature of, and drive the thermoelectric device module when the time change rate is greater than or equal to a preset value and the charge slate is greater than or equal to a preset threshold.
[Claim 5]
The battery pack cooling system of claim 1, wherein the charging current is supplied from an external charging device of the battery pack, and the current sensor is installed on a charging line connecting the battery pack and an external charging device.
[Claim 6]
The method of claim 1, wherein power for driving the thermoelectric device module is supplied from an external power supply device, and the battery pack cooling system for an electric vehicle further comprises a switch connected between the external power supply device and the thermoelectric device module, The control unit is a battery pack cooling system for an electric vehicle, characterized in that configured to drive the thermoelectric module by turning on the switch.
[Claim 7]
Cooling of a battery pack system for an electric vehicle including a battery pack including a plurality of batteries, and a water-cooled cooling device for indirectly cooling the battery by introducing a refrigerant through a refrigerant conduit mounted to allow heat conduction to the outside of the battery In the method, (a) between an inlet side refrigerant conduit through which the refrigerant flows into the battery pack among the refrigerant conduit of the water cooling system and an outlet side refrigerant conduit through which the refrigerant cooled the battery pack is discharged to the outside of the battery pack. Providing a thermoelectric device module, wherein a heat absorbing surface and a heating surface of the thermoelectric device module face each of the inlet-side refrigerant conduit and the outlet-side refrigerant conduit; (b) determining a charging slate by measuring the amount of charging current flowing through a charging line connecting the battery pack and an external charging device; And (c) when the charging slate is higher than a preset threshold, driving the thermoelectric device module to cause a temperature difference between the heat absorbing surface and the heating surface of the thermoelectric device module, thereby lowering the temperature of the refrigerant at the heat absorbing surface. Cooling method of a battery pack system for an electric vehicle comprising a; supplying to the side of the battery pack.
[Claim 8]
The method of claim 7, wherein the step (a) comprises: contacting the heat absorbing surface with the inlet side refrigerant conduit so that heat exchange between the inlet side refrigerant conduit and the outlet side refrigerant conduit through the thermoelectric element module, and the heating surface And the step of contacting the outlet side refrigerant conduit.
[Claim 9]
The cooling method of claim 7, wherein in the step (c), the thermoelectric device module is driven when the charging slate is fast charging of 2C or higher.
[Claim 10]
The method of claim 7, wherein the step (c) comprises: measuring a temperature of the battery pack; And driving the thermoelectric device module when the rate of change of time with respect to the temperature of the battery pack is greater than or equal to a preset value and the charge slate is greater than or equal to a preset threshold.
[Claim 11]
The cooling method of claim 7, wherein in step (c), power is supplied from an external power supply device to drive the thermoelectric device module.