System for diagnosing loose contact in battery pack

Abstract

The invention relates to a system for diagnosing at least one loose contact in a battery pack. A battery pack includes battery cells organized into a cell pack having a first contact terminal and a second contact terminal. The system comprises a current sensor for each battery cell group and a slave control unit. Master control unit determines a resistance between a first contact terminal of a reference cell pack and a second contact terminal of a preceding cell pack and / or a second contact terminal of a reference cell pack and a first contact terminal of a following cell pack based on a measured voltage drop received from a slave control unit and a measured current received from a current sensor and a resistor therebetween. If at least one of the determined resistances is greater than a predetermined threshold, the main control unit generates and transmits a warning indicating at least one loose contact.

Description

Technical Field

[0001] The present invention generally relates to a battery pack, and more particularly to a system and method for diagnosing at least one loose contact in a battery pack. Background Art

[0002] A battery pack typically includes a plurality of battery modules or cell groups that are electrically interconnected to produce a desired current and voltage output. A battery module includes a plurality of battery cells that are interconnected to each other. A battery module achieves a desired voltage by connecting a number of battery cells in series so that each battery cell adds its voltage potential to obtain a total terminal voltage. Similarly, a battery module achieves a desired current by connecting a number of battery cells in parallel. If a higher voltage or current is required and a larger battery cell is not available or does not meet the design constraints, one or more battery cells may be connected in series or in parallel to achieve the desired electrical output. Typically, a battery module employs a combination of series and parallel connections for its multiple battery cells. This enables design flexibility and achieves the desired voltage and current ratings using standard battery cell sizes. Conventionally, a battery cell is provided with two cell tabs or terminals, one for a positive cell tab or terminal, and the other for a negative cell tab or terminal to connect the battery cell to another battery cell or an external load. The above-mentioned series and / or parallel connection between the individual battery cells of the battery module is achieved by electrically connecting the battery tabs or terminals of the different battery cells. Typically, a plurality of standard battery cells are employed in battery modules used in various applications such as automobiles, power tools, etc. A plurality of standard cylindrical battery cells are electrically interconnected with each other in a combination of series and parallel connections to achieve a desired electrical output. Alternatively, each of the battery modules of the battery pack may have a plurality of cell groups having a plurality of battery cells that are all interconnected with each other.

[0003] Conventionally, in applications involving battery packs, multiple battery cells are connected to a wiring harness in the vehicle using connectors. In high voltage applications, many battery cells are connected in series. The battery pack is also equipped with a BMS (Battery Management System) circuit to monitor its health. Clusters of battery cells can share a common BMS circuit, i.e., a group of modules or cell groups can have the same common BMS circuit.

[0004] Loose contacts at the positive and negative terminals of a single battery cell or battery module can lead to safety hazards caused by potential arc discharge at the loose joints. Early detection of these loose contacts and determination of the magnitude of the voltage loss at the contact terminals are very important for avoiding catastrophic events. In conventional approaches, multiple temperature sensors are used to detect loose contacts at the terminals. Temperature sensors placed near or on the connectors cannot effectively detect loose contacts because the magnitude of the current flowing through the connector and the heat distribution at the connection joints affect the temperature rise. Further, it is difficult to detect arc discharge and instantaneous high heat loss at the connection joints using temperature sensors. Moreover, temperature changes in electrical connectors are relatively slow processes and therefore take time to reflect. In addition, when each connection between the battery cells that constitute each battery module is monitored by a temperature sensor, many such sensors will be required, which takes up space, increases weight and costs money in the application. Moreover, when a temperature sensor is used, it is impossible to detect the degree of contact loss or torque loss at the connection joint.

[0005] Further, the BMS circuit of a module or a group of modules can communicate with other BMS circuits of other modules of the battery pack using a CAN (Controller Area Network) bus. Therefore, the temperature change measured at the connection joint or terminal, when transmitted to the main controller of the battery pack, will take a very long time, after which the measured value is transmitted to the main controller and some instructions to remedy the fault are generated by the main controller. By this time, the damage has been done. If not promptly addressed, such unchecked loose contacts can have catastrophic consequences as it will cause thermal runaway of the cells in the battery. The BMS circuit of a conventional battery pack is also unable to interconnect the battery cells of its many battery modules.

[0006] Another way to monitor loose contacts in a battery pack is by measuring the current in the wires connecting the battery cells and battery modules of the battery pack. A reduction in current indicates some fault in the electrical connection. But this method does not indicate the location of the fault. Therefore, fault location will again require the use of multiple temperature sensors. Yet another way to measure loose contacts at a connection joint or terminal is to measure the voltage across the joint. If there is a loose contact, there will be a voltage drop across the connection joint. Therefore, by measuring the voltage across each battery cell, the voltage drop and the resulting loose contact can be detected. It is known that BMS circuits for single battery cells have the ability to monitor the health of the cell and loose contacts at the contact joints. However, when the battery cells are connected in series or when modules or groups of battery cells are connected in series, it is not possible to use the existing BMS circuits of the battery pack to measure the voltage drop at the connection joints.

[0007] Therefore, there is a need in the art for a system and method for diagnosing at least one loose contact in a battery pack that addresses at least the above-mentioned problems and limitations. Summary of the invention

[0008] In one aspect, the present invention relates to a system for diagnosing at least one loose contact in a battery pack. The battery pack includes a plurality of battery cells organized into a plurality of cell groups. Each cell group has a first contact terminal and a second contact terminal, such that the first contact terminal of a reference cell group is connected to the second contact terminal of its previous cell group, and the second contact terminal of the reference cell group is connected to the first contact terminal of its subsequent cell group. The system for diagnosing at least one loose contact in a battery pack includes a master control unit, a current sensor for each of the plurality of cell groups, and a slave control unit for each of the plurality of cell groups. The current sensor of the reference cell group is adapted to measure a current flowing through the reference cell group and transmit the measured current to the master control unit. In an embodiment, the slave control unit of the reference cell group is adapted to measure a voltage drop between its first contact terminal and the second contact terminal of its previous cell group, and a voltage drop between its second contact terminal and the first contact terminal of its subsequent cell group. In another embodiment, the slave control unit of the reference cell group is adapted to measure a voltage drop between its first contact terminal and the last battery cell of its previous cell group, and a voltage drop between its second contact terminal and the first battery cell of its subsequent cell group. The slave control unit of the reference cell group is further adapted to transmit the measured voltage drop to the master control unit. In an embodiment, the master control unit is adapted to determine the resistance between the first contact terminal of the reference cell group and the second contact terminal of its previous cell group and / or the resistance between the second contact terminal of the reference cell group and the first contact terminal of its subsequent cell group based on the measured voltage drop received from the slave control unit and the measured current received from the current sensor. In another embodiment, the master control unit is adapted to determine the resistance between the first contact terminal of the reference cell group and the last battery cell of its previous cell group and / or the resistance between the second contact terminal of the reference cell group and the first battery cell of its subsequent cell group based on the measured voltage drop received from the slave control unit and the measured current received from the current sensor. If at least one of the determined resistances is greater than a predetermined first threshold value, the master control unit generates and transmits a warning indicating at least one loose contact.

[0009] In an embodiment, the warning indicating at least one loose contact generated and transmitted by the main control unit comprises information about the contact terminal at which the loose contact has occurred.

[0010] In another embodiment, the slave control unit of the reference cell group is adapted to measure a voltage drop of each battery cell of the reference cell group and transmit the measured voltage drop to the master control unit. In an embodiment, the master control unit is adapted to determine a resistance between each battery cell of the reference cell group based on the measured voltage drop received from the slave control unit and the measured current received from the current sensor. If any of the determined resistances is greater than a predetermined second threshold value, the master control unit generates and transmits said warning indicating at least one loose contact and the location of the loose contact.

[0011] In yet another embodiment, each of the plurality of battery cell groups comprises a plurality of temperature sensors adapted to measure the temperature at a first contact terminal and a second contact terminal of the corresponding battery cell group, and the temperature at one or both terminals of one or more battery cells in the battery cells of the corresponding battery cell group.

[0012] In a further embodiment, the slave control units of the plurality of cell groups are adapted to communicate with each other and with the master control unit.

[0013] In another aspect, the present invention relates to a method for diagnosing at least one loose contact in a battery pack. The battery pack includes a plurality of battery cells organized into a plurality of cell groups. Each cell group has a first contact terminal and a second contact terminal, such that the first contact terminal of a reference cell group is connected to the second contact terminal of its preceding cell group, and the second contact terminal of the reference cell group is connected to the first contact terminal of its succeeding cell group. The method for diagnosing at least one loose contact in a battery pack comprises the following steps: measuring a current flowing through the reference cell group by a current sensor of the reference cell group; and transmitting the measured current to a master control unit. In an embodiment, the method comprises the following steps: measuring, by a slave control unit of the reference cell group: a voltage drop between a first contact terminal of the reference cell group and a second contact terminal of its preceding cell group, and a voltage drop between a second contact terminal of the reference cell group and a first contact terminal of its succeeding cell group. In another embodiment, the method comprises the following steps: measuring, by a slave control unit of the reference cell group: a voltage drop between a first contact terminal of the reference cell group and a last battery cell of its preceding cell group, and a voltage drop between a second contact terminal of the reference cell group and a first battery cell of its succeeding cell group. The method comprises the following steps: transmitting the measured voltage drop by the slave control unit of the reference cell group to the master control unit. The method further comprises the following steps: determining, by the master control unit, the resistance between the first contact terminal of the reference cell group and the second contact terminal of its previous cell group, and the resistance between the second contact terminal of the reference cell group and the first contact terminal of its subsequent cell group based on the measured voltage drop received from the slave control unit and the measured current received from the current sensor. In another embodiment, the method comprises the following steps: determining, by the master control unit, the resistance between the first contact terminal of the reference cell group and the last battery cell of its previous cell group, and the resistance between the second contact terminal of the reference cell group and the first battery cell based on the measured voltage drop received from the slave control unit and the measured current received from the current sensor. The method comprises the following steps: generating and transmitting, by the master control unit, a warning indicating at least one loose contact if at least one of the determined resistances is greater than a predetermined first threshold.

[0014] In an embodiment, the method comprises the steps of measuring, by a slave control unit of the reference cell group, a voltage drop of each battery cell of the reference cell group, and transmitting, by the slave control unit of the reference cell group, the measured voltage drop to the master control unit. The method further comprises the steps of determining, by the master control unit, a resistance between each battery cell of the reference cell group based on the measured voltage drop received from the slave control unit and the measured current received from the current sensor, and generating and transmitting, by the master control unit, said warning indicating at least one loose contact if any one of the determined resistances is greater than a predetermined second threshold. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Reference will be made to embodiments of the present invention, examples of which may be shown in the accompanying drawings. These drawings are intended to be illustrative, rather than restrictive. Although the present invention has been generally described in the context of these embodiments, it should be understood that the scope of the present invention is not intended to be limited to these specific embodiments.

[0016] Figure 1 A block diagram of an exemplary system for diagnosing at least one loose contact in a battery pack is shown in accordance with an embodiment of the present invention.

[0017] Figure 2 A schematic diagram of an exemplary reference cell group is shown for a system for diagnosing at least one loose contact in a battery pack according to an embodiment of the present invention.

[0018] Figure 3 A schematic diagram of two battery cell packs is shown of a system for diagnosing at least one loose contact in a battery pack according to a first embodiment of the present invention.

[0019] Figure 4 A schematic diagram of two battery cell packs is shown of a system for diagnosing at least one loose contact in a battery pack according to a second embodiment of the present invention.

[0020] Figure 5 A method for diagnosing at least one loose contact in a battery pack according to a first embodiment of the present invention is shown.

[0021] Figure 6 Another method for diagnosing at least one loose contact in a battery pack according to a second embodiment of the present invention is shown.

[0022] Figure 7 A schematic diagram of a system and method for diagnosing at least one loose contact in a battery pack according to a first embodiment of the present invention is shown.

[0023] Figure 8 Another schematic diagram of a system and method for diagnosing at least one loose contact in a battery pack according to a second embodiment of the present invention is shown.

[0024] Fig. 9 Another method for diagnosing at least one loose contact in a battery pack according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0025] Various features and embodiments of the present invention herein will be discerned from the following further description thereof set forth below. In the following exemplary embodiments, the battery pack is shown as being composed of a group of cells connected in series. However, it is contemplated that the disclosure in the present invention may be applied to any type of battery pack that can accommodate the present subject matter without departing from the scope of the present invention.

[0026] The present invention generally relates to a battery pack, and more particularly to a system and method for diagnosing at least one loose contact in a battery pack.

[0027] Figure 1 A block diagram of an exemplary system 100 for diagnosing at least one loose contact in a battery pack 10 according to an embodiment of the present subject matter is shown. The battery pack 10 includes a plurality of cell groups 110. In an embodiment, each cell group 110 is a separate battery module. In another embodiment, each cell group 110 is a group of cells in a battery module. Each of the plurality of cell groups 110 is comprised of a plurality of battery cells 120. Each battery cell 120 has a positive terminal and a negative terminal. The battery cells 120 of each cell group 110 are electrically interconnected to one another using any connection means known in the art, such as thin copper wire. The plurality of cell groups 110 of the battery pack 10 are further electrically interconnected to one another and communicatively interconnected. For purposes of explanation, cell group 110 has been selected as a reference cell group 110. X . Base cell group 110 X It can be any cell group 110. X The previous battery pack 110 is represented as 110 X-1 , 110 X-2 etc., and has been included in the benchmark battery pack 110 X The battery pack 110 is represented by 110 X+1 , 110 X+2 The system 100 includes a main control unit 140, a current sensor 150, and a slave control unit 160. Each of the plurality of cell groups 110 is provided with a current sensor 150. The reference cell group 110 X The current sensor 150 is adapted to measure the current flowing through the reference battery cell group 110 X The current sensor 150 measures the current of the battery cell groups 110 and transmits the measured current to the main control unit 140. In an embodiment, a single current sensor 150 may be used for all battery cell groups 110.

[0028] Figure 2 An exemplary reference cell group 110 of a system 100 for diagnosing at least one loose contact in a battery pack 10 according to an embodiment of the present invention is shown. XEach cell group 110 has a first contact terminal 112 and a second contact terminal 114. In the illustrated embodiment, the reference cell group 110 X The first contact terminal 112 is connected to the previous battery cell group 110 X-1 The second contact terminal 114 of the reference cell group 110 X The second contact terminal 114 is connected to the next battery cell group 110 X+1 The first contact terminal 112 of the battery pack 10 is connected in series. Therefore, the battery cell groups 110 in the battery pack 10 are connected in series. Each of the plurality of battery cell groups 110 is provided with a slave control unit 160. In an embodiment, each slave control unit 160 constitutes a BMS (battery management system) ASIC (application-specific integrated circuit). In another embodiment, the slave control unit 160 constitutes a CMU (battery cell management unit). The slave control unit 160 is capable of measuring the voltage of each of the battery cells 120 in the battery cell group 110. The slave control unit 160 has a hard wiring to connect the positive terminal of each of the battery cells 120 in the battery cell group 110 and the positive terminal of the last battery cell 120 N The first contact terminal 112 is connected to or is the same as the positive terminal of the first battery cell 1201 in the battery cell group 110, and the second contact terminal 114 is connected to the last battery cell 1201 in the battery cell group 110. N or the same as the negative terminal of the battery cell 120. With the help of the hard-wired connection between the positive terminal and the negative terminal of the battery cell 120 and the pins of the slave control unit 160, the slave control unit 160 senses the voltage available at each of the hard-wired points, and based on the sensed voltage, the slave control unit 160 calculates the voltage drop between the hard-wired points. In an embodiment, the slave control unit 160 can transmit all the sensed voltages to the master control unit 140, and the master control unit 140 calculates the voltage drop between these hard-wired points. In addition, in an embodiment, the slave control unit 160 transmits the voltage drop to the master control unit 140 together with the pin number that determines the voltage drop. Therefore, the master control unit 140 knows the voltage drop at the hard-wired point, and the slave control unit 160 identifier transmits the voltage drop to the master control unit 140 based on the sensed voltage. Figure 5 and Figure 6 The method described in the article is used to locate the position of loose contacts.

[0029] Figure 3 Two battery packs 110 of a system 100 for diagnosing at least one loose contact in a battery pack 10 according to a first embodiment of the present subject matter are shown. X and 110 X-1 In the illustrated embodiment, the reference battery pack 110 XThe slave control unit 160 is adapted to measure the relationship between its first contact terminal 112 and the previous cell group 110 X-1 The voltage drop between the second contact terminals 114 of the reference cell group 110 X The slave control unit 160 is further adapted to measure the relationship between the second contact terminal 114 and the next cell group 110. X+1 In the first embodiment, the slave control unit 160 has a hard-wired connection to the reference cell group 110. X The first contact terminal 112 of the previous battery cell group 110 X-1 The input pin at the second contact terminal 114 and / or the reference cell group 110 X The second contact terminal 114 of the battery cell group 110 X+1 The input pin at the first contact terminal 112.

[0030] Figure 4 Two exemplary reference cell packs 110 of a system 100 for diagnosing at least one loose contact in a battery pack 10 according to a second embodiment of the present subject matter are shown. X and 110 X-1 In the illustrated embodiment, the reference battery pack 110 X The slave control unit 160 is adapted to measure the relationship between its first contact terminal 112 and the previous cell group 110 X-1 The last battery cell 120 N Voltage drop between. Reference cell group 110 X The slave control unit 160 is further adapted to measure the relationship between the second contact terminal 114 and the next cell group 110. X+1 In the second embodiment, the slave control unit 160 has a hard-wired connection to the reference cell group 110. X The first contact terminal 112 of the previous battery cell group 110 X-1 The last battery cell 120 N The input pin at the reference cell group 110 X The second contact terminal 114 of the battery cell group 110 X+1 The input pin of the first battery cell 1201.

[0031] Reference Figure 3 and Figure 4 , Base cell group 110 X The slave control unit 160 is adapted to measure the reference cell group 110 XThe voltage drop of each battery cell 120 is measured. In an embodiment, the voltage measurement is performed by tapping the voltage of the corresponding first contact terminal 112 or the second contact terminal 114 of the corresponding battery cell group 110 or the corresponding positive terminal or negative terminal of the corresponding battery cell group battery 120, as the case may be, using any conventional voltage tapping means (such as a thin copper wire connection). In another embodiment, the voltage drop is detected by monitoring the voltage drop in the wires connecting the battery cells 120 or the battery cell group 110. Due to this, the existing components of the BMS of the battery pack 10 can be used without adding any additional circuits. In an embodiment, the voltage drop can be detected using one of the many existing cell voltage monitoring channels of the BMS ASIC of the battery pack 10. These measurements are quite accurate, with an error of less than ±2mV (millivolts), and are detected faster, within about 100 milliseconds. The measurement of the voltage drop is not affected by temperature changes in the battery pack 10.

[0032] Base cell pack 110 X The slave control unit 160 is further adapted to transmit the measured voltage drop to the master control unit 140. In an embodiment, the slave control units 160 of the plurality of cell groups 110 are adapted to communicate with each other and with the master control unit 140. The communication may be achieved via a CAN bus of the battery pack 10. In another embodiment, each of the plurality of cell groups 110 includes a plurality of temperature sensors 170. The plurality of temperature sensors 170 are adapted to measure the temperature at the first contact terminal 112 and the second contact terminal 114 of the corresponding cell group 110. In yet another embodiment, the plurality of temperature sensors 170 are disposed at one or two terminals of one or more of the battery cells 110 of the corresponding cell group 110. Thus, the temperature sensor may measure the temperature at the positive terminal and the negative terminal of the battery cell 120 of each cell group 110. Due to the limited accuracy in measuring the high voltage at the first contact terminal 112 and the second contact terminal 114 of the cell group 110 to obtain their difference, the use of typical analog circuits to accurately detect the voltage drop (in the order of mV (millivolts)) is limited. Therefore, in an embodiment, the temperature sensor 170 is placed on or near the first contact terminal 112 and the second contact terminal 114 to measure the temperature change. In another embodiment, the temperature sensors placed near the positive terminal and the negative terminal of the plurality of battery cells 120 help to more accurately measure the voltage drop between the battery cells.

[0033] Figure 5 A method 500 for diagnosing at least one loose contact in a battery pack 10 is shown according to a first embodiment of the present subject matter. In the illustrated embodiment, the reference cell group 110 X The slave control unit 160 measures 508 the first contact terminal 112 and the previous cell group 110 X-1The voltage drop between the second contact terminals 114 of the reference cell group 110 X The slave control unit 160 also measures 510 the second contact terminal 114 and the subsequent cell group 110 X+1 To perform this measurement, the battery pack 110 X You can Figure 3 Make the connections as shown. Figure 3 and Figure 5 , Base cell group 110 X The current sensor 150 measures 504 the current flowing through the reference battery pack 110 X The current of the reference battery pack is 110 X The current sensor 150 further transmits 506 the measured current to the main control unit 140. The method 500 includes the following steps: X The slave control unit 160 transmits 512 the measured voltage drop to the master control unit 140. In an embodiment, the master control unit 140 determines 514 the reference cell group 110 based on the measured voltage drop received from the slave control unit 160 and the measured current received from the current sensor 150. X The first contact terminal 112 of the previous battery cell group 110 X-1 In another embodiment, the master control unit 140 determines 516 the reference cell group 110 based on the measured voltage drop received from the slave control unit 160 and the measured current received from the current sensor 150. X The second contact terminal 114 of the battery cell group 110 X+1 If any of the one or more resistances determined by the main control unit 140 is greater than a predetermined first threshold, the main control unit 140 generates 518 and transmits 518 a warning indicating at least one loose contact.

[0034] Figure 6 Another method 500 for diagnosing at least one loose contact in a battery pack 10 according to a second embodiment of the present subject matter is shown. In the illustrated embodiment, the reference cell group 110 X The slave control unit 160 measures 522 the first contact terminal 112 and the previous cell group 110 X-1 The last battery cell 120 N Voltage drop between. Reference cell group 110 X The slave control unit 160 also measures 524 the relationship between its second contact terminal 114 and the next cell group 110 X+1 To perform this measurement, the battery pack 110 XYou can Figure 4 Make the connections as shown. Figure 4 and Figure 6 , Base cell group 110 X The current sensor 150 measures 504 the current flowing through the reference battery pack 110 X The current of the reference battery pack is 110 X The current sensor 150 further transmits 506 the measured current to the main control unit 140. The method 500 includes the following steps: X The slave control unit 160 transmits 512 the measured voltage drop to the master control unit 140. In an embodiment, the master control unit 140 determines 526 the reference cell group 110 based on the measured voltage drop received from the slave control unit 160 and the measured current received from the current sensor 150. X The first contact terminal 112 of the previous battery cell group 110 X-1 The last battery cell 120 N In another embodiment, the master control unit 140 determines 528 the reference cell group 110 based on the measured voltage drop received from the slave control unit 160 and the measured current received from the current sensor 150. X The second contact terminal 114 of the battery cell group 110 X+1 The main control unit 140 generates 518 and transmits 518 a warning indicating at least one loose contact if any one of the one or more resistances determined by the main control unit 140 is greater than a predetermined first threshold value.

[0035] As loose contact at each terminal increases, that is, when the loose contact at the terminal increases or the distance between the electrical connector and each terminal increases, the resistance at these points also increases accordingly. In an embodiment, the warning generated and transmitted by the main control unit 140 includes information about the contact terminals 112, 114 that have loose contact. The warning can be displayed on the display device 180 ( Figure 1 The warning may be displayed on a display device (such as a display device) or screen for viewing by the user of the electrical appliance using the battery and / or may be directly transmitted to a service station. The display device includes an instrument cluster of a vehicle using the battery pack 10, a personal mobile device, a personal computer, a dedicated screen on the battery pack 10, a computer device at a service station, etc. The warning may also be transmitted to a BMS or ECU (electronic control unit), which may shut down the faulty battery pack 110. Figure 6 In the illustrated embodiment, the main control unit 140 is capable of receiving the reference battery cell group 110 X The first contact terminal 112 of the previous battery cell group 110 X-1 The last battery cell 120 NThe voltage drop between and / or the reference cell group 110 X The second contact terminal 114 and the next battery cell group 110 X+1 The voltage drop between the first battery cells 1201 includes the voltage drop between the corresponding battery cells 1201, 120 N The voltage of the corresponding battery cells 1201, 120 N The individual voltages of are also known to the main control unit 140, so it can estimate and locate the voltage drop of the connector.

[0036] Figure 7 A schematic diagram of a first embodiment of a system 100 and method 500 for diagnosing at least one loose contact in a battery pack 10 is shown. To perform this measurement, the battery pack 110 X You can Figure 3 The connection is as shown. Reference cell group 110 X The current sensor 150 measures 504 the current flowing through the reference battery pack 110 X The current of the reference battery pack is 110 X The current sensor 150 further transmits 506 the measured current to the main control unit 140. The method 500 includes the following steps: X The slave control unit 160 transmits 512 the measured voltage drop to the master control unit 140. In an embodiment, the master control unit 140 determines 526 the reference cell group 110 based on the measured voltage drop received from the slave control unit 160 and the measured current received from the current sensor 150. X The first contact terminal 112 of the previous battery cell group 110 X-1 The last battery cell 120 N In another embodiment, the master control unit 140 determines 528 the reference cell group 110 based on the measured voltage drop received from the slave control unit 160 and the measured current received from the current sensor 150. X The second contact terminal 114 of the battery cell group 110 X+1 The resistance between the first battery cell 1201 of the main control unit 140 is determined. If any one of the one or more resistances determined by the main control unit 140 is greater than a predetermined first threshold value, the main control unit 140 generates 518 and transmits 518 a warning indicating at least one loose contact. This is transmitted to other ECUs via the CAN bus. In an embodiment, the resistance is determined again by the main control unit 140 even after the warning is transmitted. In another embodiment, if any one of the resistances determined by the main control unit 140 is less than the predetermined first threshold value, all faults related to the terminal are cleared and the resistance is determined again by the main control unit 140.

[0037] Figure 8 A schematic diagram of a second embodiment of a system 100 and method 500 for diagnosing at least one loose contact in a battery pack 10 is shown. To perform this measurement, the battery pack 110 X You can Figure 4 The connection is as shown. Reference cell group 110 X The current sensor 150 measures 504 the current flowing through the reference battery pack 110 X The current of the reference battery pack is 110 X The current sensor 150 further transmits 506 the measured current to the main control unit 140. The method 500 includes the following steps: X The slave control unit 160 transmits 512 the measured voltage drop to the master control unit 140. In an embodiment, the master control unit 140 determines 526 the reference cell group 110 based on the measured voltage drop received from the slave control unit 160 and the measured current received from the current sensor 150. X The first contact terminal 112 of the previous battery cell group 110 X-1 The last battery cell 120 N In another embodiment, the master control unit 140 determines 528 the reference cell group 110 based on the measured voltage drop received from the slave control unit 160 and the measured current received from the current sensor 150. X The second contact terminal 114 of the battery cell group 110 X+1 The resistance between the first battery cell 1201 of the main control unit 140 is determined. If any one of the one or more resistances determined by the main control unit 140 is greater than the predetermined first threshold value, the main control unit 140 generates 518 and transmits 518 a warning indicating at least one loose contact. In an embodiment, the resistance is determined again by the main control unit 140 even after the warning is transmitted. In another embodiment, if any one of the resistances determined by the main control unit 140 is less than the predetermined first threshold value, all faults related to the terminal are cleared and the resistance is determined again by the main control unit 140.

[0038] Fig. 9 A method 500 for diagnosing at least one loose contact in a battery pack 10 is shown according to a third embodiment of the present subject matter. In the illustrated embodiment, the reference cell group 110 X The slave control unit 160 measures 532 the reference battery cell group 110 X The voltage drop of each battery cell 120. The reference cell group 110 XThe slave control unit 160 further transmits 512 the measured voltage drop to the master control unit 140. The master control unit 140 determines 536 the reference cell group 110 based on the measured voltage drop received from the slave control unit 160 and the measured current received from the current sensor 150. X The method 500 includes the following steps: if any of the determined resistances is greater than a predetermined second threshold, generating 518 and transmitting 518 the warning indicating at least one loose contact by the main control unit 140. The first threshold and the second threshold may be preset to different values ​​based on the nature and type of battery pack 10 to which the system 100 and the method 500 are coupled. In an embodiment, the first threshold and the second threshold are equal.

[0039] Advantageously, the claimed invention provides a system and method for diagnosing at least one loose contact in a battery pack. The battery pack is applied in a high voltage system such as a vehicle, where the BMS / slave control unit can be together with the battery pack, and the master control unit can be one of the control units of the vehicle. The system and method determine the loose connection and its location in real time and quickly to avoid any disaster to the high voltage system such as the vehicle. Since each battery cell and terminal is hardwired to the slave control unit, and the slave control unit, together with the voltage drop, passes through the pins through which the voltage drop is sensed, the location of the loose contact can be accurately determined. Therefore, the master control unit knows the voltage drop and its corresponding location. The claimed configuration of the system and method for diagnosing at least one loose contact in a battery pack as described above is not routine, conventional or well known in the art, because the claimed configuration of the system and method for diagnosing at least one loose contact in a battery pack enables the following solutions to the problems existing in the conventional technology. By adopting the system and method, loose contacts between individual battery cells and between groups of cells or modules can be accurately measured with minor changes to the existing hardware of the battery pack. It is simple and cost effective to implement in a battery pack. It also does not consume a lot of space and is lighter in weight. Further, terminals using busbar electrical connections that may loosen under vibration can be monitored by the given system and method. It also allows for early and timely detection of loose contacts and accurate detection of contact loss. A temperature sensor may not be required, so the installation cost is low.

[0040] 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 modifications may be made without departing from the scope of the invention as defined in the following claims.

[0041] Reference numerals list :

[0042] 10-Battery Pack

[0043] 100-System for diagnosing loose contacts in battery packs

[0044] 110-Multiple battery packs

[0045] 110 X -Benchmark battery pack

[0046] 110 X-1 -The previous cell group of the reference cell group

[0047] 110 X+1 -The next cell group after the reference cell group

[0048] 112-first contact terminal of the battery pack

[0049] 114- Second contact terminal of the battery pack

[0050] 120-plus battery cells

[0051] 140-Main Control Unit

[0052] 150-Current Sensor

[0053] 160-Slave Control Unit

[0054] 170-Multiple Temperature Sensors

[0055] 180 - Display device for showing generated warnings.

Claims

1. A system (100) for diagnosing at least one loose contact in a battery pack (10), the battery pack (10) having a plurality of battery cells (120) organized into a plurality of cell groups (110), each cell group (110) having a first contact terminal (112) and a second contact terminal (114), wherein: Base cell group (110 X ) is connected to the first contact terminal (112) of the previous battery cell group (110 X-1 ) of the second contact terminal (114), and the reference cell group (110 X ) is connected to the second contact terminal (114) of the subsequent battery cell group (110 X+1 ), the system (100) comprising: A main control unit (140); A current sensor (150) is used for each of a plurality of battery cell groups (110), wherein the reference battery cell group (110) X ) is configured to measure the current flowing through the reference battery cell group (110 X ) and transmit the measured current to the main control unit (140); and A slave control unit (160), wherein the slave control unit (160) is used for each of the plurality of battery cell groups (110), wherein the reference battery cell group (110) X ) of the slave control unit (160) is configured as follows: Measure one or both of the following: the reference cell group (110 X ) and the first contact terminal (112) of the previous battery cell group (110 X-1 ) between the second contact terminals (114); and the reference cell group (110 X ) and the first contact terminal (112) of the previous battery cell group (110 X-1 )'s last battery cell (120 N ) between the voltage drop; Measure one or both of the following: the reference cell group (110 X ) and the second contact terminal (114) of the subsequent battery cell group (110 X+1 ) between the first contact terminal (112), and the voltage drop between the second contact terminal (114) and the next battery cell group (110 X+1 )'s voltage drop between the first battery cells (1201); transmitting the measured voltage drop to the main control unit (140); Wherein, the main control unit (140) is configured as follows: The reference cell group (110) is determined based on the measured voltage drop received from the slave control unit (160) and the measured current received from the current sensor (150). X ) and the first contact terminal (112) of the previous battery cell group (110 X-1 )'s second contact terminal (114); and The reference cell group (110) is determined based on the measured voltage drop received from the slave control unit (160) and the measured current received from the current sensor (150). X ) and the second contact terminal (114) of the subsequent battery cell group (110 X+1 )'s first contact terminal (112); or The reference cell group (110) is determined based on the measured voltage drop received from the slave control unit (160) and the measured current received from the current sensor (150). X ) and the first contact terminal (112) of the previous battery cell group (110 X-1 )'s last battery cell (120 N ) between the resistors; and The reference cell group (110) is determined based on the measured voltage drop received from the slave control unit (160) and the measured current received from the current sensor (150), the voltage drop across the second contact terminal (114) thereof X ) and the second contact terminal (114) of the subsequent battery cell group (110 X+1 ) between the first battery cells (1201); and If at least one of the determined resistances is greater than a predetermined first threshold, a warning indicating at least one loose contact is generated and transmitted on a display device (180).

2. The system (100) for diagnosing at least one loose contact in a battery pack (10) according to claim 1, wherein: The warning generated and transmitted by the main control unit (140) includes information about the contact terminals (112, 114) where the loose contact has occurred.

3. The system (100) for diagnosing at least one loose contact in a battery pack (10) according to claim 1, wherein: The reference battery pack (110 X ) is configured to: measure the reference battery cell group (110 X ) of each battery cell (120); and transmitting the measured voltage drop to the main control unit (140).

4. The system (100) for diagnosing at least one loose contact in a battery pack (10) according to claim 3, wherein: The master control unit (140) is configured to determine the reference cell group (110) based on the measured voltage drop received from the slave control unit (160) and the measured current received from the current sensor (150). X ) between each battery cell (120); if any of the determined resistances is greater than a predetermined second threshold, generating and transmitting the warning indicating at least one loose contact and the location of the loose contact.

5. The system (100) for diagnosing at least one loose contact in a battery pack (10) according to claim 1, wherein: Each of the plurality of battery cell groups (110) comprises a plurality of temperature sensors (170), wherein the plurality of temperature sensors (170) are configured to measure the temperature at a first contact terminal (112) and a second contact terminal (114) of the corresponding battery cell group (110), and the temperature at one or two terminals of one or more battery cells in the battery cells (110) of the corresponding battery cell group (110).

6. The system (100) for diagnosing at least one loose contact in a battery pack (10) according to claim 1, wherein: The slave control units (160) of the plurality of battery cell groups (110) are configured to communicate with each other and with the master control unit (140).

7. A method (500) for diagnosing at least one loose contact in a battery pack (10), the battery pack (10) having a plurality of battery cells (110) organized into a plurality of cell groups (110), each cell group having a first contact terminal (112) and a second contact terminal (114), wherein: Base cell group (110 X ) is connected to the first contact terminal (112) of the previous battery cell group (110 X-1 ) of the second contact terminal (114), and the reference cell group (110 X ) is connected to the second contact terminal (114) of the subsequent battery cell group (110 X+1 ), the method (500) comprising the following steps: By the reference battery pack (110 X ) measures (504) the current flowing through the reference battery cell group (110 X ) and transmitting (506) the measured current to a main control unit (140); By the reference battery pack (110 X ) of the slave control unit (160) measuring (508, 522) one or both of the following: the reference cell group (110 X ) and the first contact terminal (112) of the previous battery cell group (110 X-1 ) and the voltage drop between the second contact terminals (114) of the reference cell group (110 X ) and the first contact terminal (112) of the previous battery cell group (110 X-1 )'s last battery cell (120 N ) between the voltage drop; By the reference battery pack (110 X ) of the slave control unit (160) measuring (510, 524) one or both of the following: the reference cell group (110 X ) and the second contact terminal (114) of the subsequent battery cell group (110 X+1 ) between the first contact terminals (112), and the reference cell group (110 X ) and the second contact terminal (114) of the subsequent battery cell group (110 X+1 )'s voltage drop between the first battery cells (1201); By the reference battery pack (110 X ) the slave control unit (160) transmitting (512) the measured voltage drop to the master control unit (140); The reference cell group (110) is determined (514) by the master control unit (140) based on the measured voltage drop received from the slave control unit (160) and the measured current received from the current sensor (150). X ) and the first contact terminal (112) of the previous battery cell group (110 X-1 )'s second contact terminal (114); and The master control unit (140) determines (516) the reference cell group (110) based on the measured voltage drop received from the slave control unit (160) and the measured current received from the current sensor (150). X ) and the second contact terminal (114) of the subsequent battery cell group (110 X+1 )'s first contact terminal (112); or The reference cell group (110) is determined (526) by the master control unit (140) based on the measured voltage drop received from the slave control unit (160) and the measured current received from the current sensor (150). X ) and the first contact terminal (112) of the previous battery cell group (110 X-1 )'s last battery cell (120 N ) between the resistors; as well as The reference cell group (110) is determined (528) by the master control unit (140) based on the measured voltage drop received from the slave control unit (160) and the measured current received from the current sensor (150). X ) and the second contact terminal (114) of the subsequent battery cell group (110 X+1 ) between the first contact terminals (1201); as well as If at least one of the determined resistances is greater than a predetermined first threshold, a warning indicating at least one loose contact is generated (518) and transmitted (518) by the main control unit (140).

8. The method (500) for diagnosing at least one loose contact in a battery pack (10) according to claim 7, wherein: The method (500) comprises the following steps: X ) of the slave control unit (160) to measure (532) the reference cell group (110 X ) of each battery cell (120); and through the reference cell group (110 X ) the slave control unit (160) transmits (512) the measured voltage drop to the master control unit (140).

9. The method (500) for diagnosing at least one loose contact in a battery pack (10) according to claim 8, wherein: The method (500) comprises the following steps: determining (536) by the master control unit (140) the reference cell group (110) based on the measured voltage drop received from the slave control unit (160) and the measured current received from the current sensor (150) X ) between each battery cell (120); if any of the determined resistances is greater than a predetermined second threshold, the main control unit (140) generates (518) and transmits (518) the warning indicating at least one loose contact.

Images