WO2022180639A1

WO2022180639A1 - A battery pack

Info

Publication number: WO2022180639A1
Application number: PCT/IN2022/050099
Authority: WO
Inventors: Sarvani Kuchibhotla; S Shanmugasundaram; Nileshwar Pramila Rao; Samraj Jabez Dhinagar
Original assignee: Tvs Motor Company Limited
Priority date: 2021-02-23
Filing date: 2022-02-07
Publication date: 2022-09-01
Also published as: TW202245322A

Abstract

A Battery Pack The present invention discloses a battery pack. The battery pack has plurality of battery cells (10) arranged in one or more rows (R) and one or more columns (M). The battery pack (200) further has a first temperature sensor (T1) detachably attached to a first battery cell (C1) disposed in a first column (M0), a second temperature sensor (T2) detachably attached to a second battery cell (C2) disposed in a last column (Mx), and a third temperature sensor (T3) detachably attached to a third battery cell (C3) disposed substantially equidistant from the first battery cell (C1) and the second battery cell (C2). Further, each of the first temperature sensor (T1), the second temperature sensor (T2) and the third temperature sensor (T3) is coupled with a Battery Management System.

Description

TITLE OF INVENTION A Battery Pack

FIELD OF THE INVENTION

[001] The present invention relates to a battery pack.

BACKGROUND OF THE INVENTION [002] Most lithium-ion batteries are designed to operate at a pre-determined operating temperature range. However, one of the primary disadvantages in operating lithium-ion battery packs is that individual battery cells in the battery packs are prone to thermal management issues. These occur when elevated temperatures trigger heat-generating exothermic reactions which in turn further increase temperatures and potentially trigger deleterious reactions. During such an event an individual cell in the battery pack heats up to 850°C or more consequently increasing the temperature of adjacent cells within the battery pack as well. As a result, power from the battery pack is interrupted due to the overall damage caused.

[003] Typically, a temperature sensor is attached to or integrated with the battery packs to measure their current temperature. When the temperature of the batteries falls outside normal operating temperature range, electronics of the concerned system usually activate a cooling device (e.g., a fan) or a heating device (e.g., a heater) to adjust the temperature of the batteries to bring them within normal operating temperature range. However, as it is important to have a temperature sensor, it is equally important to have an accurate measurement of the temperature. This is because, when temperatures in the battery packs increase, they do not increase uniformly. Hence, several attempts have been made to measure the temperature of the battery pack accurately.

[004] In one such attempt, a battery power source is provided which includes a chassis, in which a cooling air path is formed, with the chassis comprising a cooling air inlet; a plurality of cells arranged in the cooling air path; and a temperature sensor. The temperature sensor includes: a sensor section that is inserted from an outside of the chassis and fixed to the through hole for fixing sensor and a front end portion of the sensor section thermally contacts a region to be measured of the cell; and a wire that is drawn from a portion, which is exposed to an outside of the chassis, of the sensor section and is set up inside a groove formed on an outer peripheral surface of the chassis wall.

[005] In another attempt, a power supply device is provided with eight temperature sensors. Each temperature sensor is fixed to a surface of the battery so as to be thermally coupled thereto and detects the temperature of the battery. In this power supply device, the battery modules are arranged side by side in two rows, temperature sensors are arranged at both sides and two intermediate points of each row, and each row has four temperature sensors, for a total of eight temperature sensors. Temperature of the battery is thus detected. The plurality of temperature sensors are arranged to detect a cell having highest temperature, lowest temperature, cells whose temperature easily changes, and the like. [006] In yet another attempt, a sensor fixing hole is formed in the top wall of a battery case, a temperature sensor unit is detachably inserted into the sensor fixing hole, and the 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. [007] However, there are several problems associated with the aforementioned technologies. One such problem is that, measuring surface temperature of the battery pack leads to an inappropriate, inaccurate, as well as a delayed temperature measurement. Further, many techniques use localised temperature measurements and are invasive. A hole is bored into the cells or the battery casing to mount the temperature sensors. Such techniques require causing an undesired damage to the individual cells and the battery pack. Another problem associated with existing technologies is that they require multiple temperature sensors. Multiple temperatures sensors lead to difficulty in routing of wires and thus connecting the temperature sensors to a control unit. This in turn increases cost and labour in installation and maintenance. Yet another problem associated with the existing technology is interference of temperature sensors with coolant channels in the battery pack. Also, if the temperatures of the battery packs are left unmonitored, a powered device in which the battery packs are employed may malfunction and get damaged due to any kind of explosion. [008] Thus, there is a need in the art for a battery pack with temperature measurement and a method for controlling operation of a powered device, such as, a vehicle based on the temperature measurement of the battery pack, which addresses at least the aforementioned problems. SUMMARY OF THE INVENTION

[009] The present invention in one aspect is directed to a battery pack having a plurality of battery cells arranged in one or more rows and one or more columns; a first temperature sensor detachably attached to a first battery cell, out of the plurality of battery cells, disposed in a first column, a second temperature sensor detachably attached to a second battery cell, out of the plurality of battery cells, disposed in a last column, and a third temperature sensor detachably attached to a third battery cell, out of the plurality of battery cells, disposed substantially equidistant from the first battery cell and the second battery cell; wherein each of the first temperature sensor, the second temperature sensor and the third temperature sensor is coupled with a Battery Management System.

[010] In an embodiment of the invention, the first battery cell is disposed at center of the first column. In another embodiment, the second battery cell is disposed at center of the last column. In yet another embodiment, the third battery cell is disposed in a central column. In a further embodiment of the invention, the third battery cell is disposed at center of the central column.

[011] In an embodiment of the invention, the first battery cell is disposed first in a central row, the second battery cell is disposed last in the central row, and the third battery cell is disposed at center of the central row.

[012] In another embodiment of the invention, the battery pack has additional temperature sensors other than the first temperature sensor, the second temperature sensor, the third temperature sensor, whereby the additional temperature sensors are detachably attached to battery cells positioned symmetrical to the third battery cell.

[013] In yet another embodiment, the first temperature sensor, the second temperature sensor, the third temperature sensor, and the additional temperature sensors are selected from a group consisting of a thermistor, a resistance temperature detector, and a thermocouple.

[014] In a further embodiment of the invention, the first temperature sensor, the second temperature sensor, the third temperature sensor, and the additional temperature sensors are detachably attached at a longitudinal center of the battery cells. [015] In another embodiment of the invention, the battery pack has a top cell holder and a bottom cell holder, the top cell holder and the bottom cell holder further comprising a plurality of grooves for routing a first wire from the first temperature sensor, a second wire from the second temperature sensor and a third wire from the third temperature sensor to the Battery Management System.

[016] In yet another embodiment, the Battery Management System has a Battery Management board; and a plurality of pins mounted on the board, the plurality of pins configured to receive to receive a first coupler connected to the first wire, a second coupler connected to the second wire and a third coupler connected to the third wire. [017] In another aspect the present invention is directed towards a method for controlling operation of a motor vehicle comprising at least one battery pack, the method comprising steps of: arranging plurality of battery cells of the battery pack in one or more rows and one or more columns; attaching a first temperature sensor to a first battery cell disposed in a first column, a second temperature sensor to a second battery cell disposed in a last column, and a third temperature sensor to a third battery cell disposed substantially equidistant from the first battery cell and the second battery cell; routing a first wire, a second wire and a third wire from each of the first temperature sensor, the second temperature sensor, and the third temperature sensor respectively, through a plurality of grooves to a Battery Management System; transmitting temperatures of the battery cells from the Battery Management System to a vehicle control unit; and determining a maximum temperature of the battery pack from the temperatures received by the vehicle control unit; comparing the maximum temperature of the battery pack with a predetermined threshold temperature; and controlling operation of the motor vehicle based on the maximum and minimum temperatures. [018] In an embodiment of the invention, the controlling operation of the motor vehicle comprises changing drive mode of the motor vehicle and reducing speed of the motor vehicle, if the maximum temperature of the battery pack is less than the predetermined threshold temperature. [019] In another embodiment, the controlling operation of the motor vehicle comprises switching off the motor vehicle and initiating instant cooling of the battery pack if the maximum temperature of the battery pack is greater than the predetermined threshold temperature and a temperature flag is set.

[020] In yet another embodiment, the predetermined threshold temperature is set at 60°C. In yet another embodiment, the controlling operation of the motor vehicle comprises electrically charging the battery pack if the maximum temperature of the battery pack goes below the predetermined threshold temperature.

BRIEF DESCRIPTION OF THE DRAWINGS [021 ] Reference will be made to embodiments of the invention, examples of which may be illustrated in accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments. Figure 1 shows an exploded view of a battery pack in accordance with an embodiment of the invention.

Figure 2 shows a battery module in accordance with an embodiment of the invention. Figure 3 shows an exploded view of the battery module in accordance with an embodiment of the invention.

Figure 4 shows a top view of the battery module in accordance with an embodiment of the invention. Figure 5 shows the battery module in accordance with an embodiment of the invention.

Figure 6 shows a graph of recorded temperatures of individual cells in accordance with an embodiment of the invention.

Figure 7a shows a temperature sensor in accordance with an embodiment of the invention.

Figure 7b shows a temperature sensor attached to an individual cell in accordance with an embodiment of the invention.

Figure 8 shows a graph of recorded temperatures in different areas (positive terminal, longitudinal center, negative terminal) of an individual battery cell in accordance with an embodiment of the invention.

Figure 9 shows a flowchart of a method for controlling operation of a motor vehicle comprising at least one battery pack in accordance with an embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION

[022] The present invention generally relates to a battery pack, more particularly it relates to measurement of temperature of the battery pack.

[023] Referring to Figure 1 , the battery pack 200 of the present invention has a housing 150 which functions as a protective casing. The housing 150 has a top wall 150a, a bottom wall 150b, and opposing side walls 150c, 150d, 150e and 150f. Further, the battery pack 200 of the present invention has a battery module 100 disposed inside the housing 150. The battery module 100 has a plurality of battery cells 10. Referring to the embodiment depicted in Figure 4, the plurality of cells 10 are arranged in one or more rows R1 to R12 and one or more columns M0 to Mx and are connected serially and/ or parallelly with each other.

[024] Referring to Figures 2 and 3, the plurality of cells 10 of the battery module 100 are received by a top cell holder 20a and a bottom cell holder 20b (shown clearly in Figure 3) in order to restrict independent movement of the individual battery cells. In an embodiment of the invention, the top cell holder 20a and the bottom cell holder 20b each have a plurality of grooves 22 (shown in Figure 5 as well) for routing of wires in and out of the battery module 100. Further, the plurality of cells 10 of the battery module 100 are coupled with a Battery Management System (BMS). The BMS is an electronic system which comprises a BMS board 30 and manages the rechargeable battery pack 200 by protecting the battery pack 200 from operating outside its safe operating temperature, monitoring its state, calculating temperature data, reporting that data, controlling environment, authenticating and/ or balancing the battery pack 200.

[025] Referring now to Figure 3, in order to measure temperature of the battery pack 200, the present invention has a plurality of temperature sensors. The temperature sensors are detachably attached to individual battery cells in the battery pack 200. Accordingly, as seen in Figure 3, the battery module 100 of the battery pack 200 has a first temperature sensor T1 detachably attached to a first battery cell C1. Similarly, a second temperature sensor T2 is detachably attached to a second battery cell C2 and a third temperature sensor T3 is detachably attached to a third battery cell C3. In the present invention, and as shown in Figure 4, the first battery cell C1 is disposed in a first column MO of the battery module 100. The second battery cell C2 is disposed in a last column Mx of the battery module 100, while the third battery cell C3 is disposed substantially equidistant from the first battery cell C1 and the second battery cell C2. Further, each of the first temperature sensor T1 , the second temperature sensor T2, and the third temperature sensor T3 is coupled with the Battery Management System (BMS).

[026] Further, as shown in Figure 3, more particularly, in Figures 7a and 7b, the first temperature sensor T1 is connected to a first coupler X1 by a first wire W1. Similarly, the second temperature sensor T2 is connected to a second coupler X2 by a second wire W2 and the third temperature sensor T3 is connected to a third coupler X3 by a third wire W3. In an embodiment of the invention, the battery pack 200 has a plurality of corresponding pins 40 positioned on one side of the BMS board 30 or on either side of the BMS board 30. The corresponding pins 40 receive the respective couplers X1 , X2, X3 and are further coupled with the BMS in order to measure and control temperature changes in the battery pack 200. As described hereinabove, the first wire W1 , the second wire W2, and the third wire W3 are guided through the plurality of grooves 22 present on the top cell holder 20a and the bottom cell holder 20b for operably coupling the first temperature sensor T1 , the second temperature sensor T2, and the third temperature sensor T3 with the BMS.

[027] As shown in the graph of Figure 6, from various experiments conducted, battery cells disposed in central locations of the columns of the battery pack 200, showed maximum temperature deviation thereby affording a prompt temperature control mechanism. Therefore, in an embodiment of the invention and as depicted in Figures 3 and 4, the first battery cell C1 is disposed at center of the first column M0. Alternatively, the first battery cell C1 is disposed first in a central row R6. The second battery cell C2 is disposed at center of the last column Mx. Alternatively, the second battery cell C2 is disposed last in the central row R6. While the third battery cell C3 is disposed at central column Me. In another embodiment of the invention, and as shown in Figures 3 and 4, the third battery cell C3 is disposed at center of the central column Me, alternatively, the third battery cell C3 is disposed at center of the central row R6.

[028] There are several instances whereby large battery packs having battery cells arranged in 20 rows or more are used for larger power outputs. In such cases, to measure the temperature of the entire battery pack accurately, there are additional temperature sensors used other than the first temperature sensor T1 , the second temperature sensor T2, the third temperature sensor T3. As shown in Figure 4, in an embodiment of the invention, when number of rows in the battery module 100 is twenty or more, a fourth temperature sensor T4 (not shown) is detachably attached to a fourth battery cell C4 and a fifth temperature sensor T5 (not shown) is detachably attached to a fifth battery cell C5. In another embodiment, the fourth battery cell C4 and the fifth battery cell C5 are disposed in the central row R6 and are adjacent to the third battery cell C3 whereby the fourth battery cell C4 and the fifth battery cell C5 are disposed on either side of the third battery cell C3. In a further embodiment of the invention, the additional temperature sensors (not shown) are detachably attached to battery cells which are positioned symmetrical to the third battery cell C3. Thus, in yet another embodiment of the invention, increase in number of rows results in increase in number of temperature sensors positioned attached to battery cells which are positioned symmetrical to the third battery cell C3.

[029] Referring now to the graph shown in Figure 8 which is a plot of temperatures recorded at a positive terminal, negative terminal and longitudinal center of an exemplary battery cell versus charging and discharging time of the battery cell. From various experiments conducted, it was found that while recording any kind of temperature change, a maximum output was obtained at the longitudinal center of the battery cell when the cell is discharging. Thus, along the length of the entire battery cell, maximum temperature is observed at the longitudinal center of the cell. As shown in Figure 7a, the first temperature sensor T1 is connected to the first coupler X1 by the first wire W1. Accordingly, as shown in figure 7b, the first temperature sensor T1 is detachably attached to the first battery cell C1 at its longitudinal center. In an embodiment, the temperature sensor is detachably attached to the battery cell by using an adhesive means including, but not limited, to an adhesive tape, glue etc. In another embodiment of the invention, the temperature sensor is either a thermistor, or a resistance temperature detector, or a thermocouple or any such temperature sensor. In an embodiment of the invention, the battery pack 200 may be employed in any powered device such as, a vehicle, heavy machinery, power backups, etc., and based on the temperature of the battery pack 200, the operation of the powered device is controlled to avoid any kind of catastrophes [030] Referring to Figure 9, the present invention discloses a method 500 for controlling operation of a motor vehicle comprising at least one battery pack 200. At step 510, a plurality of battery cells 10 of the battery pack 200 are arranged in one or more rows R and one or more columns M. At step 520, the first temperature sensor T1 is attached to the first battery cell C1 disposed in the first column M0. Similarly, the second temperature sensor T2 is attached to the second battery cell C2 disposed in the last column Mx, and the third temperature sensor T3 is attached to the third battery cell C3 disposed substantially equidistant from the first battery cell C1 and the second battery cell C2. At step 530, the first wire W1 , the second wire W2, and the third wire W3 are routed from the temperature first sensor T1 , the second temperature sensor T2, and the third temperature sensor T3 respectively, which are detachably attached to the first battery cell C1 , the second battery cell C2, and the third battery cell C3. As explained hereinabove, the first wire W1 , the second wire W2, and the third wire W3 are routed through the plurality of grooves 22 to the BMS board 30 to the battery management system. At step 540, temperatures of the battery cells C1 , C2 and C3 are transmitted from the BMS to a vehicle control unit. The temperatures of the battery cells C1 , C2 and C3 so received are processed by the vehicle control unit. In an embodiment, the temperatures of the battery cells C1 , C2 and C3 are processed by the BMS. Accordingly, following measures are taken by the vehicle control unit based on temperature readings received from the battery cells: at step 550a, determining maximum and minimum temperature thresholds of the battery pack from the temperatures received by the vehicle control unit; at step 550b, comparing the maximum temperature of the battery pack 200 with a predetermined threshold temperature; and at step 550c, controlling operation of the motor vehicle by the vehicle control unit based on the maximum and minimum temperatures. Accordingly, as shown in Figure 9, if the maximum temperature of the battery pack 200 goes below the predetermined threshold temperature, the vehicle control unit changes drive mode of the motor vehicle and speed of the motor vehicle is reduced. If the maximum temperature of the battery pack 200 goes above the predetermined threshold temperature, the motor vehicle is switched off immediately and instant cooling of the battery pack 200 is initiated by the vehicle control unit. In an embodiment of the invention, the predetermined threshold temperature is set at 60°C. In another embodiment of the invention, a temperature flag is set when the maximum temperature is greater than the predetermined threshold temperature and based on the temperature flag, the vehicle control unit changes drive mode of the motor vehicle and reduces speed of the motor vehicle or initiates cooling of the battery pack 200. Thus, if the temperature of the battery pack 200 goes below the predetermined threshold temperature, electric charging of the battery pack 200 is initiated.

[031] Advantageously, the present invention uses a minimum number of temperature sensors yet achieves optimum temperature measurements. This also offers an ease of routing wires from the temperature sensors to the coupler. The minimum number of wires routed through the grooves obviates slacking and also do not interfere with air cooling channels in the battery module. Further, the temperature sensors are detachably attached to the battery cells, thereby obviating any kind of invasive techniques. Owing to localised attachments of the temperature sensors, localized failures of individual battery cells are also detected. Furthermore, with the grooves provided along the length of the cell holders, the assembly process of the battery pack is guided and simplified; the wires and their contact of the cells remain intact ensuring continuous temperature measurement of the battery pack. Further still, due to the optimum temperature measurements, efficient cooling systems and protocols can be designed. Additionally, the present invention thus aids in optimizing parameters like state of charge (SOC) linked to performance and state of health (SOH) linked to battery lifetime and prevents thermal runaway of the battery pack. Also, such control mechanism in a vehicle based on the temperature of the battery pack ensures safety of the rider and the vehicle and prevents any untoward accidents from occurring. [032] While the present invention has been described with respect to certain embodiments, it will be apparent to those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims.

Claims

CLAIMS:

1 . A battery pack (200) comprising: a plurality of battery cells (10) arranged in one or more rows (R) and one or more columns (M); a first temperature sensor (T1) detachably attached to a first battery cell (C1), out of the plurality of battery cells (10), disposed in a first column (MO); a second temperature sensor (T2) detachably attached to a second battery cell (C2), out of the plurality of battery cells (10), disposed in a last column (Mx); and a third temperature sensor (T3) detachably attached to a third battery cell (C3), out of the plurality of battery cells (10), disposed substantially equidistant from the first battery cell (C1) and the second battery cell (C2); wherein each of the first temperature sensor (T1), the second temperature sensor (T2), and the third temperature sensor (T3) is coupled with a Battery Management System.

2. The battery pack (200) as claimed in claim 1 , wherein the first battery cell (C1) is disposed at center of the first column (MO).

3. The battery pack (200) as claimed in claim 1 , wherein the second battery cell (C2) is disposed at center of the last column (Mx).

4. The battery pack (200) as claimed in claim 1, wherein the third battery cell (C3) is disposed in a central column (Me).

5. The battery pack (200) as claimed in claims 1 and 4, wherein the third battery cell (C3) is disposed at center of the central column (Me).

6. The battery pack (200) as claimed in claim 1 , wherein the first battery cell (C1) is disposed in a first position in a central row (R6), the second battery cell (C2) is disposed at a last position in the central row (R6), and the third battery cell (C3) is disposed at a center position of the central row (R6).

7. The battery pack (200) as claimed in claim 1 , comprises additional temperature sensors other than the first temperature sensor (T1), the second temperature sensor

(T2), the third temperature sensor (T3), whereby the additional temperature sensors are detachably attached to battery cells positioned symmetrical to the third battery cell (C1).

8. The battery pack (200) as claimed in claims 1 or 7, wherein the first temperature sensor (T1), the second temperature sensor (T2), the third temperature sensor (T3), and the additional temperature sensors are selected from a group consisting of a thermistor, a resistance temperature detector, and a thermocouple.

9. The battery pack (200) as claimed in claims 1 or 7, wherein the first temperature sensor (T1), the second temperature sensor (T2), the third temperature sensor (T3), and the additional temperature sensors are detachably attached at a longitudinal center of the battery cells (C1 , C2, C3).

10. The battery pack (200) as claimed in claim 1 , comprising a top cell holder (20a) and a bottom cell holder (20b), the top cell holder (20a) and the bottom cell holder (20b) further comprising a plurality of grooves (22) for routing a first wire (W1) from the first temperature sensor (T1), a second wire (W2) from the second temperature sensor (T2) and a third wire (W3) from the third temperature sensor (T3) to the Battery Management System.

11. The battery pack (200) as claimed in claim 10, wherein the Battery Management System comprises a Battery Management board (30); and a plurality of pins (40) mounted on the board (30), the plurality of pins (40) configured to receive to receive a first coupler (X1) connected to the first wire (W1), a second coupler (X2) connected to the second wire (W2) and a third coupler (X3) connected to the third wire (W3).

12. A method (500) for controlling operation of a motor vehicle comprising at least one battery pack (200), the method (500) comprising the steps of: arranging (510) a plurality of battery cells (10) of the battery pack (200) in one or more rows (R) and one or more columns (M); attaching (520) a first temperature sensor (T1) to a first battery cell (C1) disposed in a first column (M0), a second temperature sensor (T2) to a second battery cell (C2) disposed in a last column (Mx), and a third temperature sensor (T3) to a third battery cell (C3) disposed substantially equidistant from the first battery cell (C1) and the second battery cell (C2); routing (530) a first wire (W1), a second wire (W2) and a third wire (W3) from each of the first temperature sensor (T1), the second temperature sensor (T2), and the third temperature sensor (T3) respectively, through a plurality of grooves (22) to a Battery Management System; transmitting (540) temperatures of the battery cells (C1 , C2, C3) from the Battery Management System to a vehicle control unit; and determining (550a) a maximum temperature and a minimum temperature of the battery pack from the temperatures received by the vehicle control unit; comparing (550b) the maximum temperature of the battery pack (200) with a predetermined threshold temperature; and controlling operation (550c) of the motor vehicle by the vehicle control unit based on the maximum and minimum temperatures.

13. The method (500) as claimed in claim 12, wherein the controlling operation of the motor vehicle comprises changing drive mode of the motor vehicle and reducing speed of the motor vehicle, if the maximum temperature of the battery pack (200) is less than the predetermined threshold temperature.

14. The method (500) as claimed in claim 12, wherein the controlling operation of the motor vehicle comprises switching off the motor vehicle and initiating instant cooling of the battery pack (200) if the maximum temperature of the battery pack (200) is greater than the predetermined threshold temperature and a temperature flag is set.

15. The method (500) as claimed in claims 12 to 14, wherein the predetermined threshold temperature is set at 60°C.

16. The method (500) as claimed in claim 12, wherein the controlling operation of the motor vehicle comprises electrically charging the battery pack (200) if the maximum temperature of the battery pack (200) goes below the predetermined threshold temperature.