Abstract:
A power pack system includes an energy storage system having a plurality of energy storage devices and a thermal management system. The thermal management system includes a battery ventilation system connected to energy storage system for achieving and maintaining a predetermined temperature within energy storage system by providing a two way circulation of a working fluid. Further, the system includes a housing having a top cover and a bottom cover to receive and secure the energy storage devices therein. The top cover and bottom cover configured to retain said energy storage devices in a sealable manner. Further, a method for achieving and maintaining a pre determined temperature within an energy storage system includes providing two way circulation of a working fluid and maintaining a uniform flow velocity of the fluid at least inside the energy storage system.

Description:
FIELD OF INVENTION 
       [0001]    The disclosed embodiments relate generally to a power pack and more particularly, but not by way of limitation, to a power pack having a ventilation system for achieving and maintaining an optimum temperature range within the power pack pack. 
       BACKGROUND 
       [0002]    In the recent days, use of electrical devices has dramatically increased across multiple fields like transportation, businesses, education and so on. Proper function of electrical devices calls for reliable source of power for the electrical devices. Generally, the electrical devices that use electrical energy as the source of power include an energy storage system. Power packs such as battery packs are commonly used as energy storage systems in many electrical systems. A battery pack includes a plurality of batteries which are used to store energy in a chemical form. 
         [0003]    In devices such as electric vehicles, batteries are used to power the motor system of the vehicle. Batteries in such devices store electrical and/or mechanical energy in the form of chemical energy and thereafter, supply the stored chemical energy in the form of electrical energy to the motor system. The chemical reactions in batteries are dependent on temperature. The chemical reactions may be exothermic, where heat is generated, or may be endothermic, where heat is absorbed during the process of the chemical reaction. In exothermic reactions, the batteries are subjected to overheating because the chemical reaction reinforces the heat generated by the current flow. 
         [0004]    Generally, for a battery to have a high performance and longer life, the battery should be operated within an optimum temperature range. If the battery is in operation for a substantially long duration, the heat generated within the battery will cause the temperature within the battery to rise beyond the optimum temperature threshold thereby decreasing the performance and life of the battery. More often than not, the temperature range for operating a battery as specified by the battery manufacturer is much narrower than the temperature range for operating the battery as desired by the manufacturer of a device, for example the manufacturer of a vehicle, in which the battery is indented to be used. Further, the temperature variation from module to module in a battery pack leads to a different charge or discharge behavior of each module resulting in a decreased efficiency of the battery pack. 
         [0005]    Furthermore, if an electric vehicle, is to be operated in extreme cold condition, the battery used therein should be heated to initiate the charging process Therefore, the battery assembly should be constructed such that by heating the battery pack, the temperature of the battery pack should rise within a minimal time period and further, the temperature deviation within the battery pack should be minimum. 
         [0006]    In view of the above, there is a need for a power pack system which is capable of heating the energy storage system when the device, in which the power pack is used, is operated in extreme cold condition. Further, there is a need for a power pack system which is capable of dissipating heat generated by the chemical reaction within a battery cell. 
       OBJECT 
       [0007]    An object is to provide a power pack system for achieving and maintaining an optimum temperature range. 
         [0008]    Another object is to provide a power pack system for dissipating heat generated in the cells included therein. 
         [0009]    A further object is to provide a power pack system which is capable of heating and cooling the energy storage system to the predetermined temperature. 
         [0010]    Another object is to provide a power pack system which is configured to facilitate two directional flow of the air for heating the energy storage system. 
         [0011]    Yet another object is to provide a power pack system which is configured to facilitate a passage of air inside the energy storage system at a uniform velocity. 
         [0012]    These and other objects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications. 
     
    
     
       BRIEF DESCRIPTION OF FIGURES 
         [0013]    Embodiments are illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which: 
           [0014]      FIG. 1A  depicts a power pack system having a ventilation system, according to an embodiment as disclosed herein; 
           [0015]      FIG. 1B  is a perspective view of a battery module to be included in the power pack system, according to an embodiment as disclosed herein; 
           [0016]      FIG. 1C  depicts a perspective view of the power pack system with a top cover, according to an embodiment as disclosed herein; 
           [0017]      FIG. 1D  is a sectional view of the power pack system, according to the embodiment as disclosed herein; 
           [0018]      FIG. 1E  is a perspective view of the power pack system with guide plates, according to an embodiment disclosed herein; 
           [0019]      FIG. 2  is an exploded view of the fan and heater assembly; 
           [0020]      FIG. 3A  illustrates baffle plate, according to a embodiment disclosed herein; 
           [0021]      FIG. 3B  shows the baffle plate secured to a bottom cover of the power pack system, according to an embodiment disclosed herein; 
           [0022]      FIG. 3C  shows the baffle plate secured to an inner portion of the top cover of the power pack system, according to an embodiment disclosed herein; 
           [0023]      FIGS. 4A-4B  show the actuator assembly according to the embodiments as disclosed herein; 
           [0024]      FIGS. 5A-5C  show the power pack operating in a heating mode; 
           [0025]      FIGS. 6A-6C  show the power pack operating in a cooling mode; and 
           [0026]      FIG. 7  is a graph showing the battery module temperature. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein. 
         [0028]    Referring now to the drawings, and more particularly to  FIGS. 1A through 1E , where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments. 
         [0029]      FIG. 1A  depicts a power pack system  100  having an energy storage system such as a battery pack  10  and a thermal management system including a ventilation system  20 . The battery pack  10  includes a plurality of having a plurality of energy storage devices such as battery modules  102 . Further, the battery pack  10  includes a bottom cover  104 , and a top cover  106 . As shown in  FIG. 1B , each of the battery modules  102  has a housing H. The housing H includes a first casing  102   a  configured to receive a plurality of cells  102   c.  It should be noted that for the purpose of this description, the energy storage system is considered as a battery pack  10  and the battery modules  102  are considered as a Lithium-Ion battery modules. Furthermore, for the purpose of this description, the number of battery modules  102  is considered as twenty four (24) and the number of cells  102   c  in each of the module  102  is considered as nine (9). The first casing  102   a  defines a plurality of openings ◯ to allow passage of air. In one embodiment, each of the cells  102   c  is slid inside the first casing  102   a.  The cells  102   c  are arranged one above the other inside the first casing  102   a.  The cells  102   c  define a predetermined gap there between to allow passage of air through the openings ◯. It should be noted that, any alternative arrangement of the cells  102   c  within the housing H without otherwise deterring the intended function of the structure as set forth herein is also within the scope of this invention. The thermal management system further includes system architecture to control the ventilation system  20  and other components of the thermal management system. 
         [0030]    The housing H further includes a second casing  102   b  configured to retain the cells  102   c  inside the first casing  102   a.  Further, an internal cell busbar  102   d  is provided between the second casing  102   b  and cell terminal  102   e  of each of the cells  102   c.  Each of the battery modules  102  is adapted to be received inside the bottom cover  104 . The battery modules  102  are arranged adjacent to each other on the bottom cover  104  so that the opening ◯ provided in the first casing  102   a  of one battery module  102  is in alignment with the opening ◯ provided in the first casing  102   a  of the adjacent battery module  102 . Further, as shown in  FIG. 1C , the top cover  106  is provided on the battery modules  102  received in the bottom cover  104  thereby enclosing the cells  102   c  and the battery modules  102 . The top cover  106  and the bottom cover  104  may be sealed by a gasket (not shown) and a triple compound (not shown) to avoid any leakage. 
         [0031]    Further, the ventilation system  20  includes a recirculation duct  200 , a first fan  220 , a second fan  222 , a third fan  224 , a fourth fan  226 , a first heater  230 , a second heater  232 , a first baffle plate  234 , a second baffle plate  236 , a first actuator assembly  250  and a second actuator assembly  260 . The first fan  220 , the second fan  222 , the third fan  224 , the fourth fan  226 , the first heater  230  and the second heater  232  are connected to the thermal management system (not shown). Further, each of the first fan  220 , the second fan  222 , the third fan  224 , the fourth fan  226  are provided with a feedback system which communicates with the thermal management system to regulate heating or cooling of the power pack system  100 . The recirculation duct  200  further includes a first end  201  and a second end  202  and at least a first channel C 1  and a second channel C 2  defined between the first end  201  and the second end  202  of the recirculation duct  200 . Further, in one embodiment the recirculation duct  200  is provided external to the battery modules  102  and below the top cover  106 . As shown in  FIG. 1E , the first channel C 1  and the second channel C 2  are supported by guide plates G 1  and G 2 , respectively. The guide plates G 1  and G 2  are secured to the bottom cover  104 . 
         [0032]    As shown in  FIG. 1D , the first fan  220 , the second fan  222  and the first heater  230  are located near the first end  201  of the recirculation duct  200 . Further, the third fan  224 , the fourth fan  226  and the second heater  232  are located near the second end  202  of the recirculation duct  200 . The first actuator assembly  250  is in contact with the first end  201  of the recirculation duct  200  and the second actuator assembly  260  is in contact with the second end  202  of the recirculation duct  200 .  FIG. 2  shows an exploded view of a fan-heater assembly. 
         [0033]    Further, the first baffle plate  234  is positioned near the battery modules  102  of the battery pack  10 . The first heater  230  is configured to be placed adjacent to the first baffle plate  234  and away from the battery modules  102 . The second fan  222  is positioned adjacent to the first heater  230  and away from the first baffle plate  234 . Further, the first fan  220  is positioned adjacent to the second fan  222  and away from the first baffle plate  234 . The first actuator assembly  250  which is in direct contact with the first end  201  of the recirculation duct is also configured to be in direct fluid communication with the first fan  220 . 
         [0034]    Similarly, the second baffle plate  236  is positioned near the battery modules  102  of the battery pack  10 . The second heater  232  is configured to be placed adjacent to the second baffle plate  236  and away from the battery modules  102 . The third fan  224  is positioned adjacent to the second heater  232  and away from the second baffle plate  236 . Further, the fourth fan  226  is positioned adjacent to the third fan  224  and away from the second baffle plate  236 . The second actuator assembly  260  which is in direct contact with the second end  201  of the recirculation duct is also configured to be in direct fluid communication with the fourth fan  226 . 
         [0035]    Further, as shown in  FIG. 3A , each of the first and second baffle plates,  234  and  236 , defines a plurality of orifices  235  with varying diameter. The baffle plates  234  and  236 , along with the orifices  235  essentially facilitate lesser pressure drop and substantially uniform air flow velocity for each battery modules  102 . The first and second baffle plates,  234  and  236 , are generally rectangular in shape and define the orifices across the width thereof. Further, each of the baffle plates  234  and  236  has a notch N at a center thereof. The orifices  235  of varying diameter are located on either side of the notch N. 
         [0036]    As shown in  FIGS. 3B and 3C , in one embodiment, each of the baffle plates  234  and  236  may be directly provided on the battery modules  102  in which case, the baffle plates  234  and  236 , may be secured to the bottom cover  104  by known attachment means. Further, as shown in  FIG. 3D , in another embodiment, each of the baffle plates  234  and  236  may be provided on an inner side surface  106   s  of the top cover  106  of the battery pack  10 . The top cover  106  further includes a plurality of battery holder  106   a  to secure the battery modules  102 . 
         [0037]    Further, as shown in  FIGS. 4A and 4B , each of the actuator assemblies  250  and  260  has a plenum chamber P, an opening  256 , a flap F and an actuator mechanism M. The opening  256  is in fluid communication with the corresponding first and second end  201  and  202  of the recirculation duct  200 . Further, the flap F of each of the actuator assemblies  250  and  260  is adapted to be moveable between a closed position, where the flap F closes the opening  256  of each of the actuator assemblies  250  and  260 . The Flap F is connected to the actuator mechanism M which in turn is connected to a thermal management system (not shown). 
         [0038]    Further, explained below is the operation of the power pack system  100  having an energy storage system such as a battery pack  10  and a ventilation system  20  and a method of heating and cooling the battery module  102  of the battery pack  10  thereby the battery pack  10  using the ventilation system  20 . 
         [0039]    If the power pack system  100  is supposed to be operated in an extreme cold condition, the battery pack  10  has to be initially heated for the charging process to begin. Temperature sensors (not shown) of the thermal management system (not shown) senses the external temperature and the temperature of the battery back  10 . If the temperature is below a predetermined degree, the thermal management system activates heating mode for the battery pack  10 .  FIGS. 5A-5C  illustrate the heating mode of the battery pack  10 . In the heating mode, the first and second heaters  230  and  232  are in the ON state and the flap F of each of the actuator assemblies  250  and  256  is in the open position. The heating mode includes a first cycle in which air flows in a counterclockwise direction and a second cycle in which air flows in a clockwise direction. In the first cycle, the second fan  222  and the fourth fan  226  are in the ON state. Specifically, the second fan  222  will be in a push mode where the air is pushed through the battery modules  102  and the fourth fan  226  will be in a suction mode where the air pushed by the second fan  222  is sucked by the fourth fan  226 . During the process, air pushed from the second fan  222  will pass through the first heater  230  and then, via the orifices  251  of the first baffle plate  234 , hot air is passed through the battery modules  102 . Thereafter, the hot air is sucked by the fourth fan  226  via the second baffle plate  236  through the second heater  232  thereby again heating the air. The hot air from the fourth fan  226  is allowed to pass through the second end  202  of the recirculation duct  200 . Thereafter, the air is passed through each of the first and the second channel C 1  and C 2  towards the first end  201  of the recirculation duct  200  and then through the first actuator assembly  250 . The second fan  222  receives the air from the first actuator assembly  250  and the process as mentioned above repeats and for a predetermined duration. 
         [0040]    Similarly, in the second cycle, the first fan  220  and the third fan  224  are in the ON state. Specifically, the third fan  224  will be in a push mode where the air is pushed through the battery modules  102  and the first fan  220  will be in a suction mode where the air pushed by the third fan  224  is sucked by the first fan  220 . During the process, air pushed from the third fan  224  will pass through the second heater  232  and then, via the orifices  251  of the second baffle plate  236 , hot air is passed through the battery modules  102 . Thereafter, the hot air is sucked by the first fan  220  via the first baffle plate  234  through the first heater  230  thereby again heating the air. The hot air from the first fan  220  is allowed to pass through the first end  201  of the recirculation duct  200 . Thereafter, the air is passed through each of the first and the second channel C 1  and C 2  towards the second end  202  of the recirculation duct  200  and then through the second actuator assembly  260 . The third fan  224  receives the air from the second actuator assembly  260  and the process as mentioned above repeats and for a predetermined duration. The two directional flow of the hot air via the recirculation duct  200  during the heating mode ensures that the battery pack  10  and the battery modules  102  attains a predetermined temperature required for initial charging of the battery pack  10 . 
         [0041]    Further,  FIGS. 6A-6C  illustrate the cooling mode of the battery pack  10 . In the cooling mode, the first and second heaters  230  and  232  are in the OFF state and the flap F of each of the actuator assemblies  250  and  256  is in the closed position. The cooling mode includes a first cycle in which air flows towards the second actuator assembly  260  and a second cycle in which air flows towards the first actuator assembly  250 . In the first cycle, the second fan  222  and the fourth fan  226  are in the ON state. Specifically, the second fan  222  will be in a push mode where the air is pushed through the battery modules  102  and the fourth fan  226  will be in a suction mode where the air pushed by the second fan  222  is sucked by the fourth fan  226 . During the process, air pushed from the second fan  222  will pass through the orifices  251  of the first baffle plate  234  and then the air is passed through the battery modules  102 . Thereafter, the air is sucked by the fourth fan  226  via the second baffle plate  236 . The air from the fourth fan  226  is allowed to pass through the second actuator assembly  260  and to the external environment without otherwise passing through the second end  202  of the recirculation duct  200 . Further, since the heater is in the OFF state, the air will essentially have ambient temperature which in effect causes the battery modules  102  and hence the battery pack  10  to dissipate the heat accumulated. 
         [0042]    Similarly, in the second cycle, the first fan  220  and the third fan  224  are in the ON state. Specifically, the third fan  224  will be in a push mode where the air is pushed through the battery modules  102  and the first fan  220  will be in a suction mode where the air pushed by the third fan  224  is sucked by the first fan  220 . During the process, air pushed from the third fan  224  will pass through the orifices  251  of the second baffle plate  236  and then the air is passed through the battery modules  102 . Thereafter, the air is sucked by the first fan  220  via the first baffle plate  234 . The air from the fourth fan  226  is allowed to pass through the first actuator assembly  250  and to the external environment without otherwise passing through the first end  201  of the recirculation duct  200 . Further, since the heater is in the OFF state, the air will essentially have ambient temperature which in effect causes the battery modules  102  and hence the battery pack  10  to dissipate the heat accumulated. 
         [0043]    Several tests were conducted for heating and cooling of the battery pack in different ambient conditions ranging from −15° C. to 45° C. till the battery module reaches the maximum temperature of 20° C. The tests conducted illustrate that the battery modules may be heated uniformly. 
         [0044]      FIG. 7  illustrates the observation on the test that has been conducted on 24 Li-ion battery modules. The battery modules are provided in three rows namely back row, front row and the middle row, where each row comprises of 8 battery modules. Further, it can be noticed from the  FIG. 7  that the battery module temperature between the three rows are substantially same and the temperature deviation is observed as 2.9° C. which is less than the desirable limit of 3° C. 
         [0045]    The embodiment disclosed herein specifies a power pack system  100  having a thermal management system with ventilation system  20  for achieving and maintaining an optimum temperature inside the power pack system  100 . The thermal management system controls at least the fan assembly and the heater assembly provided in the ventilation system  20  through system architecture. Therefore, it is understood that the scope of the protection is extended to such a program and in addition to a computer readable means having a message therein, such computer readable storage means contain program code means for implementation of one or more steps of the method, when the program runs on a server or mobile device or any suitable programmable device. The method is implemented in a preferred embodiment through or together with a software program written in e.g. Very high speed integrated circuit Hardware Description Language (VHDL) another programming language, or implemented by one or more VHDL or several software modules being executed on at least one hardware device. The hardware device can be any kind of device which can be programmed including e.g. any kind of computer like a server or a personal computer, or the like, or any combination thereof, e.g. one processor and two FPGAs. The device may also include means which could be e.g. hardware means like e.g. an ASIC, or a combination of hardware and software means, e.g. an ASIC and an FPGA, or at least one microprocessor and at least one memory with software modules located therein. Thus, the means are at least one hardware means and/or at least one software means. The method embodiments described herein could be implemented in pure hardware or partly in hardware and partly in software. The device may also include only software means. Alternatively, the invention may be implemented on different hardware devices, e.g. using a plurality of CPUs. 
         [0046]    The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.