DESC:TECHNICAL FIELD
[0001] The present subject matter relates generally to a battery pack. More particularly but not exclusively the present subject matter relates to a temperature sensor element in the battery pack.
BACKGROUND
[0002] Nowadays, with the advancement in the technology, an electric or hybrid electric vehicle make use of one or more power source to drive the vehicle. The one or more power source is a battery to provide power to run a motor which in turn runs one or more wheels of the vehicle. The battery pack includes one or more cells and are connected through one or more interconnectors to provide an electrical connection. The one or more cells are arranged in a module consisting of a top casing and a bottom casing. The one or more cells are welded to a metal strip known as the interconnector, forming a battery pack. The one or more interconnector is connected to a BMS (Battery management system). The BMS obtains the individual parameters of the one or more cells to monitor the SoC (state of charge) and SoH (state of health) of the battery pack.

BRIEF DESCRIPTION OF THE DRAWINGS

[0003] The details are described with reference to an embodiment of a battery pack along with the accompanying diagrams. The same numbers are used throughout the drawings to reference similar features and components.
[0004] Figure 1 exemplarily illustrates an exploded top perspective view of a battery pack.
[0005] Figure 2(a) exemplarily illustrates a side perspective exploded view of the battery module as per an embodiment of the present invention.
[0006] Figure 2(b) exemplarily illustrates a top view of the battery module showing the routing of one or more cord set of a temperature sensing element inside the battery pack.
[0007] Figure 2(c) exemplarily illustrates a side view of the battery module showing the routing of one or more cord set of a temperature sensing element outside of the battery pack.
[0008] Figure 3 exemplarily illustrates a top perspective view of the battery module as per an embodiment of the present invention with the base member.
[0009] Figure 4(a) exemplarily illustrates the cord set with a second coupler as per the embodiment of the present invention.
[00010] Figure 4(b) exemplarily illustrates the cord set with the second coupler as per the embodiment of the present invention, attached to the individual cell of the battery pack.

DETAILED DESCRIPTION

[0001] Generally, the connection between one or more cell and a battery management system (BMS) is very crucial for efficient working of the battery pack. An interconnector plate made up of metal is used to form the connection between the one or more cells and the BMS. The interconnector plate is welded on the one or more cells and is connected to the BMS through a wiring harness. The BMS plays a vital role in monitoring the health of the battery pack. The BMS monitors the voltage, charging current, temperature, state of charge, and the like of the one or more cell for ensuring effective working and long life of the battery pack. In many battery packs, rise in temperature of the battery pack is a major concern. Sensing abnormal increase in the cell temperature aids a battery management system to shut down the battery pack to prevent thermal runaway for safety of a user of a vehicle having such a battery pack. Sensing the high temperature in the battery pack can help in designing an optimised cooling system in order to get uniform distribution of temperature in the battery pack, thus avoiding hotspots. A minimal range of say for example-3-5°C is permissible between a hottest cell and a coldest cell in the battery pack, otherwise this may lead to deterioration in life of the battery pack. Also, low temperature sensing can be crucial during charging process.
[0002] Accordingly, active cooling/heating of the battery pack has to be carried out. Thus, an optimized cooling mechanism is needed for the battery pack. In order to optimize the cooling mechanism, firstly an amount of temperature rise, a rate of temperature rise, an area where the temperature is more in the battery pack, and the like is to be identified. For the above-mentioned purpose, a temperature sensor like a thermistor is utilized in the battery pack to sense the temperature of the cells in the battery pack. In a known art, a thermistor is pasted onto the cell using a sticker or adhesive. The battery pack is filled with phase change material as a thermal management solution for keeping the battery pack temperature low. However, the phase change material causes the sticker or adhesive to peel/wear off the adhesiveness due to wear and tear from the cell surface, after a few operational cycles of the battery pack. This results in detection of incorrect values of temperature of the one or more cells by the temperature sensing element disposed in the battery pack. The wearing off the sticker results in improper contact of the temperature sensing element with the one or more cells. This leads in improper or wrong reading of the temperature and also leads to improper optimisation of parameters like SOC and SOH.
[0003] Many manufacturers have tried to solve the above-mentioned problem. In a known art, a temperature sensor is provided with a sensor section that is inserted from an outside of a chassis and fixed to a through hole for fixing the sensor, and a front-end portion of the sensor section thermally contacts a region to be measured of the cell. A wire that is drawn from a portion, which is exposed to an outside of the chassis of the sensor section is set up inside a groove formed on an outer peripheral surface of the chassis wall. In yet another known prior art, a sensor fixing hole is formed in a top wall of a battery case, a temperature sensor unit is detachably inserted into the sensor fixing hole and fixed. A tip of a temperature detecting part of the temperature sensor unit is brought into contact with battery cells within the battery case to detect the temperature of the battery cells. Even if the temperature sensor unit malfunctioned, only the temperature sensor unit is replaceable without replacing the temperature sensor unit together with a battery. However, these means are not able to solve the problem explained above. Therefore, there is need to provide a means of attaching the temperature sensing element with the one or more cell with utmost durability. Thus, there is a need to overcome the above-mentioned problems and other problems of known art.
[0004] An objective of the present subject matter is to provide a durable means of attaching the temperature sensing element on to the one or more cells and at appropriate place to detect the correct and accurate temperature of the one ore more cells of the battery pack. The present subject matter further aims to provide a simple attachment means of temperature sensing element which is durable, easy to assemble, easy to handle, and safe to operate for the entire life cycle of the battery pack. The present subject matter is described using an exemplary battery pack which is used in the vehicle, whereas the claimed subject matter can be used in any other type of application employing above-mentioned battery pack, with required changes and without deviating from the scope of invention.
[0005] As per an aspect of the present subject matter, a battery pack includes one or more cells; one or more cell is configured to form one or more battery module; and one or more temperature sensing element is configured to be connected to the one or more cells. The one or more cells are configured with a holding sleeve. The holding sleeve is configured to hold one or more temperature sensor. The one or more temperature sensor is attached to a center position of the one or more cells of the battery pack.
[0006] As per an aspect of the present subject matter, the one or more temperature sensing element includes one or more temperature sensor, and a cord set. The one or more temperature sensor is disposed on the one or more cell. The one end of the cord set having the temperature sensor is connected to at one end and another end of the cord set is connected to a base member.
[0007] As per an aspect of the present subject matter, the base member is configured to have one or more temperature sensing element coupler. The one or more temperature sensing element coupler is configured to be connected with a battery module management system to receive one or more inputs.
[0008] As per an aspect of the present subject matter, the one or more temperature sensing element senses abnormal increase in cell temperature beyond a threshold limit by the battery module management system, and the battery module management system shuts down the battery pack to prevent the thermal runaway, in case of the battery pack temperatures rises beyond the threshold limit.
[0009] As per another aspect of the present subject matter, the one or more cells of the battery pack are selected to connect the temperature sensing element, depending upon the total number of cells and the one or more dimensions of the battery pack.
[00010] As per an aspect of the present subject matter, the one or more cells are provided with the holding sleeve on the entire outer body of one or more cell, the holding sleeve holds the temperature sensor tightly along the one or more cell, the temperature sensor is placed between an outer body of the one or more cells and the holding sleeve.
[00011] As per an aspect of the present subject matter, the holding sleeve is configured to be coated with a phase changing material to avoid wear and tear of the holding sleeve and for cooling the battery pack.
[00012] As per an aspect of the present subject matter, the battery pack is configured to switch between a power mode to an eco-mode, if the temperature of the battery pack goes beyond the threshold limit.
[00013] As per an aspect of the present subject matter, a method for battery pack temperature detection, the method comprising the steps of connecting, one or more cells to form one or more battery module, housed within the battery pack with one or more temperature sensing element; placing, the one or more temperature sensor within a holding sleeve, the one or more temperature sensing element includes a temperature sensor, and a cord set, wherein the temperature sensor being attached at a center position of the one or more cell; and determining, a temperature of the battery pack during operation of the battery pack.
[00014] As per an aspect of the present subject matter, the one or more temperature sensing element senses abnormal increase in cell temperature beyond a threshold limit by a battery module management system, and the battery module management system shuts down the battery pack to prevent the thermal runaway, in case of the battery pack temperatures rises beyond the threshold limit.
[00015] As per an aspect of the present subject matter, the one or more cells of the battery pack are selected to connect the temperature sensing element, depending upon the total number of cells and the one or more dimensions of the battery pack. The embodiments of the present invention will now be described in detail with reference to a battery pack along with the accompanying drawings. However, the present invention is not limited to the present embodiments. The present subject matter is further described with reference to accompanying figures. It should be noted that the description and figures merely illustrate principles of the present subject matter. Various arrangements may be devised that, although not explicitly described or shown herein, encompass the principles of the present subject matter. Moreover, all statements herein reciting principles, aspects, and examples of the present subject matter, as well as specific examples thereof, are intended to encompass equivalents thereof.
[00016] Fig.1 exemplarily illustrates an exploded top perspective view of a battery pack 100. A battery pack casing 102 protects one or more battery modules 100a (shown in fig.2) from outside environment and prevents it from getting damaged. The battery module 100a includes one or more cells 104a (shown in fig.2) disposed in one or more holder 104 to hold the one or more cells stable in its required position, during the operation of the vehicle (not shown) and also to maintain the required cell arrangement and cell spacing. The battery module 100a includes the one or more cells 104a, one or more cell holder 104, and one or more interconnectors 106. The one or more cells 104a provides the electric energy to drive a vehicle (not shown). The one or more cell holder 104 is provided with one or more voltage sensing points 112 for one or more interconnectors 106 to be placed. The one or more interconnectors 106 are used to make electrical connection between the one or more cells 104a. The one or more cells 104a are welded to the interconnector 106 to form the battery module 100a. The one or more interconnectors 106 are placed above the one or more battery module 100a and one or more sensing points 112 are provided on the module 100a to hold the one or more interconnectors 106 in place. In the present embodiment, the battery module casing 102 includes a first casing 102a, a top casing 102b, and a bottom casing 102c. The first casing 102a accommodates the cell holder 104 along with the one or more cells 104a and supports the one or more sides of the battery module 100a. The top casing 102b covers the battery module 100a from a top portion of the battery module 100a. The bottom casing 102c provides a support to the one or more battery modules 100a. In an embodiment, the one or more casing 102 can be one of the aluminum casing. An output port 118 and a socket 120 are provided in the top casing 102b to bring out the connection to the outside of the battery pack 100.
[00017] Fig.2(a) exemplarily illustrates a side perspective exploded view of the battery module 100a as per an embodiment of the present invention. Fig.2(b) exemplarily illustrates a top view of the battery module 100a showing the routing of the one or more cord set 116 of a temperature sensing element 110 inside the battery pack 100. Fig.2(c) exemplarily illustrates a side view of the battery module 100a showing the routing of one or more cord set 116 of a temperature sensing element 110 outside of the battery pack 100. Fig.2(a), fig.2(b) and Fig.2(c) shall be discussed together. Fig.2(a) shows an exploded view of the of the battery module 100a. In the present embodiment, the one or more cells 104a are held by the one or more cell holders 104. The cell holder 104 includes a bottom holder 104aa and a top holder 104ab. The bottom holder 104aa accommodates the one or more cells 104a from a bottom portion of the one or more cells 104a and have partitions provided between two horizontal rows. The top holder 104ab supports the one or more cells 104a from a top portion of the one or more cells 104a. The top holder 104ab also accommodates the one or more interconnectors 106 so as to form connections between the one or more cells 104a with the one or more interconnectors 106. A base member 108 is attached at a side portion of the battery module 100a to provide as a connection interface between the one or more battery module 100a and a battery module management system (not shown). However, the base member 108 can be positioned at any one of the sides of the battery module 100a, depending on the requirement and configuration of the battery pack 100. In the present embodiment, the base member 108 includes one or more electrical components (not shown) connected and placed on a portion of the base member 108. The one or more base member 108 is sandwichedly disposed between the one or more interconnectors 106 and the one or more battery module management system (not shown). In the present embodiment, the base member 108 can be a printed circuit board (PCB) acting as an insulation member between the one or more battery module 100a and the battery module management system. However, any other material can be used exhibiting similar properties than the PCB. One side of the base member 108 is non conducting, and the non-conducting side of the base member 108 is faced towards the battery module 100a, acting as an insulator between the battery module 100a and the battery module management system. The other side of the base member 108 is faced towards the battery module management system and accommodates one or more electrical connections.
[00018] In the present embodiment, the one or more temperature sensing elements 110 are placed at three different locations in the battery pack 100. The temperature sensing elements 110 is disposed on the one or more cells 104a. However, the number of cells 104a and the location/position of the temperature sensing elements 110 can be increased or decreased depending upon different factors. The different factors may include the total number of cells in the battery pack 100, configuration of the battery pack 100, dimension of the battery pack 100, number of drive cycle of the battery pack 100, maximum and minimum temperature of the battery pack 100, requirement of high or low currents from the pack 100, and the like. In the present embodiment, the temperature sensing element 110 is placed at three locations, namely, on a first cell which is located at centre of the battery pack 100, a second cell which is located at the left side centre, and a third cell which is located at right side centre of the battery pack 100, when viewed from a top portion of the battery module 100a as shown in fig.2(a) and fig.2(b). However, the positions of the temperature sensing element 110 can be changed based on the above-mentioned factors.
[00019] The position of the temperature sensing element 110 ensures that the measurement of temperature is distributed evenly in the pack 100. The position/location of the temperature sensing element 110 ensures the following: a) capturing of increase in temperature of the one or more cells of the battery pack 100 due to internal reactions during riding of the vehicle, b) capturing of temperature efficiently will aid in designing an effective cooling system by which thermal runaway can be avoided, ensuring the safety of the rider of the vehicle, c) sensing temperature distribution in the battery pack 100 which helps to keep a check on battery operating window limits. Sensing abnormal increase in cell temperatures helps battery module management system to shut down the battery pack to prevent thermal runaway for safety of the rider of the vehicle. High temperature sensing in the battery pack 100 can help in designing optimised cooling system in order to get uniform distribution of temperature in the battery pack thus avoiding hotspots. A temperature range of 3-5°C is permissible between a hottest cell and a coldest cell in the battery pack 100 otherwise a greater variation in the temperature range may lead to deterioration in life of the battery pack 100. Also, a low temperature sensing can be crucial during charging. Accordingly, active cooling/heating of the battery pack 100 has to be carried out. Temperature monitoring play’s crucial role in optimisation of parameters like state of charge (SOC) linked to performance, state of health (SOH) linked to battery lifetime and also linked to rider safety aspects. In the present embodiment, as shown in fig.2(b) and 2(c), the one or more cord set 116 with their respective wiring is shown. The wires are routed from the individual cell 104a out of the battery pack 100 from three positions, namely, centre, left centre side, right centre side of the battery pack 100, from one of the sides of the battery pack 100.
[00020] Fig.3 exemplarily illustrates a top perspective view of the battery module 100a as per an embodiment of the present invention with the base member 108. The temperature sensing element 110 includes a temperature sensor 114 (shown in fig.4(a)), and the cord set 116 (shown in fig.2(c)). The base member 108 provides connection for the cord 116 of the temperature sensing element 110 (shown in fig.2(a)), so as to be connected with the battery module management system by means of one or more temperature sensing couplers 122, provided on the sides of the base member 108. The one or more interconnectors 106 are connected to battery module management system by means of the base member 108. The base member 108 also includes the one or more voltage sensing points 112, where each of the one or more interconnectors 106 are getting attached. The cord sets 116 from the battery pack 100 gets connected with the one or more temperature sensing couplers 122 provided on the base member 108. The base member 108 is provided with one or more third set of couplers 126 so as to be coupled with the battery module management system. The base member 108 collects the signal from each interconnector 106 and the one or more temperature sensors 114 and transfers to the battery module management system by means of the cord set 116 and the one or more temperature sensing couplers 122 provided on the base member 108. The battery module management system consists of a temperature sensing circuit (not shown) that gets electrically connected to the one or more temperature sensing couplers 122 internally that monitors and measures the cell temperatures to control the battery module 100a operations.
[00021] Fig.4(a) exemplarily illustrates the cord set 116 with a second set of couplers 124 as per the embodiment of the present invention. Fig.4(b) exemplarily illustrates the cord set 116 with the second set of couplers 124 as per the embodiment of the present invention, attached to the individual cell of the battery pack 100. A first end of the cord set 116 is provided with the second set of couplers 124 which gets connected to the one or more temperature sensing couplers 122, provided at the base member 108. A second end of the cord set 116 having the temperature sensor 114 is attached to the individual cell 104a. In an embodiment, the optimum position for placing the second end with the sensor 114 of the cord set 116 is at the centre of the individual cell 104a. In another embodiment, the position for placing the second end of the cord set 116 can be one of a top or a bottom portion of the cell 104a. The second end placed at the centre of the cell 104a provides the maximum temperature. To ensure that the second end is always adequately attached to the individual cell 104a and does not gets eroded by the phase change material poured into the battery pack 100, a holding sleeve 128 is provided. The holding sleeve 128 is a pouch like structure, used to hold the individual cell 104a. The holding sleeve 128 is elastic in nature so that it can elastically accommodate the cells. Using the holding sleeve 128, instead of the adhesive tape, covers at least a portion of the cell 104a and tightly holds the temperature sensor 114 on to the cells 104a, thus avoiding peeling off of the sensor 114, which might happen in the adhesive type in presence of the phase change material or due to any other harsh environment. In an embodiment, the holding sleeve 128 may cover an entire outer portion of the cell. Since the holding sleeve 128 covers the cell from top to bottom, it can hold the temperature sensors 114 adequately. Also, due to the elastic nature of the holding sleeve 128, the holding sleeve 128 puts pressure on the temperature sensor 114 to hold it onto a fixed position and do not allow to slide it over or move from its position. Thus, even if the phase change material goes inside the holding sleeve 114, it is in liquid form due to absorption of latent heat from the battery pack 100, it will not be able to move the temperature sensor 114 because of the elastic nature of the holding sleeve 128. Any kind of temperature sensors can be used to capture the temperature of the battery pack 100. However, the sensor 114 should have very less response time and very low contact resistance so that the correctness of measured value can be achieved.
[00022] In the present embodiment, a middle of the cell records high temperatures and is thus selected for the placement of temperature sensors 114. Operating the battery pack 100 at different C rates (charging rate of the battery) and temperatures makes the pack 100 behave differently depending on the parameters like number of cells, design of the battery pack 100, test ambient, drive cycles, and the like. For example, operating at higher C rates and higher temperatures leads cell to reach high temperatures hence optimum temperature sensor positioning and placement helps to achieve the aforementioned benefits. Selecting multiple cells ensures capturing of temperature evenly in the pack. In the present embodiment, the holding sleeve 128 is coated with a material that is compatible with PCM like PU (Polyurathane), Silicon or epoxy to avoid wear and tear of the holding sleeve 128. This also avoids wrong readings in long run, as it protects the holding sleeves 128 from wear and tear. In one embodiment, the temperature sensor 114 can be attached with the cell 104a using adhesives as well as the holding sleeves 128. In case, where the temperature of the battery pack 100 increases beyond a threshold value, the vehicle is transitioned from a power mode to a normal mode to limit the power drawn from the battery pack 100, based on the sensed temperature, so as to limit the rise in temperature. Also, during fast charging, if the temperature of the battery pack 100 increases beyond a pre-determined value, the charging rate can be slowed down to avoid rise in temperature. So, detecting the accurate temperature aids in devising and implementing intelligent charging strategy. The present invention aids in ensuring a safer battery pack 100 with longer life, eliminating thermal runaway, optimizing parameters like SOC and SOH.
[00023] The claimed steps as discussed herein are not routine, conventional, or well understood in the art, as the claimed steps enable the following solutions to the existing problems in conventional technologies.
[00024] Many other improvements and modifications may be incorporated herein without deviating from the scope of the invention.

List of Reference numerals
100: Battery pack
100(a): Battery module
102: Battery pack casing
102(a): First casing
102(b): Top casing
102(c): Bottom casing
104: One or more cell holder
104(aa): Bottom holder
104(ab): Top holder
104(a): One or more cells
106: One or more interconnectors
108: One or more base member
110: Temperature sensing element
112: One or more voltage sensing points
114: One or more temperature sensors
116: Cord set
118: Output port
120: Socket
122: One or more temperature sensing couplers
124: Second set of couplers
126: Third set of couplers
128: Holding sleeve

,CLAIMS:I/We claim:
1. A battery pack (100) comprising:
one or more cells (104a);
one or more cells (104a) being configured to form one or more battery module (100a); and
one or more temperature sensing element (110) being configured to be connected to the one or more cells (104a),
wherein the one or more cells (104a) being connected to a holding sleeve (128), the holding sleeve (128) being configured to hold one or more temperature sensor (114) of the one or more temperature sensing element (110),
wherein the one or more temperature sensor (114) being attached to a center position of the one or more cells (104a) of the battery pack (100).

2. The battery pack (100) as claimed in claim 1, wherein the one or more temperature sensing element (110) includes the one or more temperature sensor (114), and a cord set (116),
wherein the one or more temperature sensor (114) being disposed on the one or more cells (104a),
wherein one end of the cord set (116) is connected to the temperature sensor (114) and another end of the cord set (116) being connected to a base member (108).
3. The battery pack (100) as claimed in claim 2, wherein the base member (108) being configured to have one or more temperature sensing element coupler (122), the one or more temperature sensing element coupler (122) being configured to be connected with a battery module management system to receive one or more inputs from the battery pack (100).
4. The battery pack (100) as claimed in claim 3, wherein the one or more temperature sensing element (110) senses abnormal increase in cell temperature beyond a threshold limit by the battery module management system, and the battery module management system shuts down the battery pack (100) for preventing the thermal runaway, in case of the battery pack (100) temperatures rises beyond the threshold limit.
5. The battery pack (100) as claimed in claim 1, wherein the one or more cells (104a) of the battery pack (100) being selected to connect the temperature sensing element (110), depending upon a total number of cells and one or more dimensions of the battery pack (100).
6. The battery pack (100) as claimed in claim 1, wherein the one or more cells (104a) being connected with the holding sleeve (128) on an entire outer body of the one or more cell (104a), the holding sleeve (128) configured to hold the temperature sensor (114) tightly along the one or more cell (104a), the temperature sensor (114) being placed between the outer body of the one or more cells (104a) and an inner side of the holding sleeve (128).
7. The battery pack (100) as claimed in claim 6, wherein the holding sleeve (128) being configured to be coated with a phase changing material for avoiding wear and tear of the holding sleeve (128) and for cooling the battery pack (100).
8. The battery pack (100) as claimed in claim 4, wherein the battery pack (100) being configured to switch between a power mode to an eco-mode, when the temperature of the battery pack (100) goes beyond the threshold limit.
9. A method for determining temperature of one or more cells of a battery pack (100), the method comprising the steps of:
connecting, the one or more cells (104a) to form one or more battery module (100a), housed within the battery pack (100) with one or more temperature sensing element (110);
connecting the one or more cells to a holding sleeve,
placing, one or more temperature sensing element (110), including one or more temperature sensor (114) and a cord set (116), within an inner side of the holding sleeve (128), wherein the temperature sensor (114) being attached at a center position of the one or more cells (104a); and
determining, a temperature of the battery pack (100) during operation of the battery pack (100).

10. The method for battery pack (100) temperature detection as claimed in claim 9, wherein, the one or more temperature sensing element (110) senses abnormal increase in cell temperature beyond a threshold limit by a battery module management system (not shown), and the battery module management system shuts down the battery pack (110) to prevent the thermal runaway, in case of the battery pack (100) temperatures rises beyond the threshold limit.
11. The method for battery pack (100) temperature detection as claimed in claim 9, wherein, the one or more cells (104a) of the battery pack (100) being selected to connect the temperature sensing element (110), depending upon the total number of cells and the one or more dimensions of the battery pack (100).