System for diagnosing poor contacts in a battery pack

Abstract

The present invention relates to a system for diagnosing at least one contact failure in a battery pack. The battery pack includes battery cells organized into cell groups having first and second contact terminals. The system includes a current sensor and a slave control unit for each cell group. The master control unit determines a resistance between the first contact terminal of a reference cell group and the second contact terminal of a preceding cell group and / or a resistance between the second contact terminal of the reference cell group and the first contact terminal of a succeeding cell group based on measured voltage drops received from the slave control units and measured currents received from the current sensors. The master control unit generates and communicates an alert indicating at least one contact failure if at least one of the determined resistances is greater than a predetermined threshold value.

Description

[Technical Field]

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

[0002] A battery pack typically includes multiple battery modules or cell groups electrically interconnected to create a desired current and voltage output. A battery module includes multiple battery cells interconnected to each other. A battery module achieves a desired voltage by connecting several battery cells in series, with each battery cell adding its voltage potential to derive a total terminal voltage. Similarly, a battery module achieves a desired current by connecting several battery cells in parallel. When a higher voltage or current is required and a larger battery cell is unavailable or does not fit within design constraints, one or more battery cells can be connected in series or in parallel to achieve the desired electrical output. Generally, a battery module employs a combination of series and parallel connections for its multiple battery cells. This allows for design flexibility and allows for the use of standard battery cell sizes to achieve desired voltage and current ratings. Conventionally, battery cells are provided with two cell tabs or terminals, one positive and the other negative, for connecting the battery cell to another battery cell or to an external load. The aforementioned series and / or parallel connections between individual battery cells of a battery module are achieved by electrically connecting the cell tabs or terminals of the different battery cells. Typically, multiple standard battery cells are employed within battery modules used in various applications such as automobiles, power tools, etc. Multiple standard cylindrical battery cells are electrically interconnected with each other in series and parallel combinations to achieve a desired electrical output. Alternatively, each of the battery modules of a battery pack may have multiple cell groups, each having multiple battery cells all interconnected with each other.

[0003] Traditionally, in applications involving battery packs, multiple battery cells are connected together in a wiring harness inside a vehicle using connectors. In high-voltage applications, many battery cells are connected in series. Battery packs are also equipped with a BMS (Battery Management System) circuit to monitor their health. A group of battery cells may share one common BMS circuit, i.e., a group of modules or cell groups can have the same common BMS circuit.

[0004] Poor contact at the positive and negative terminals of individual battery cells or battery modules can pose safety concerns due to potential arcing at loose joints. Early detection of these poor contacts at contact terminals and confirmation of the magnitude of voltage loss are crucial to avoiding catastrophic events. Conventional approaches employ multiple temperature sensors to detect poor contact at terminals. Because the magnitude of the current flowing through the connector and the heat distribution at the connection joint affect the temperature rise, temperature sensors installed near or on the connector cannot effectively detect poor contact. Furthermore, arcing and instantaneous high heat loss at connection joints make detection difficult using temperature sensors. Temperature fluctuations in electrical connectors are a fairly slow process and therefore take time to reflect. Furthermore, when each connection between the battery cells that make up each battery module is monitored by a temperature sensor, a large number of such sensors are required, which adds space, weight, and money to the application. Furthermore, when temperature sensors are employed, they cannot detect the extent of contact loss or torque loss at connection joints.

[0005] Furthermore, the BMS circuitry of a module or group of modules can communicate with other BMS circuits in other modules of the battery pack using a CAN bus. Therefore, when temperature fluctuations measured at connection joints or terminals are transmitted to the battery pack's master controller, it can take a very long time for the measured values to be transmitted to the master controller and for the master controller to generate any instructions to correct the fault. By this time, damage has already occurred. If such unchecked contact failures are not addressed in a timely manner, they can be catastrophic, promoting thermal runaway of cells within the battery. Conventional battery pack BMS circuits also cannot interconnect the battery cells of its many battery modules.

[0006] Another method of monitoring for contact failures in a battery pack is by measuring the current in the electrical wires connecting the battery cells and battery modules of the battery pack. A decrease in current is an indication of some kind of fault in the electrical connection. However, this method does not indicate the location of the fault. Therefore, locating the fault again requires the use of multiple temperature sensors. Yet another method of measuring contact failures at connection joints or connection terminals is by measuring the voltage across the joint. If there is a contact failure, there will be a voltage drop across the connection joint. Therefore, by measuring the voltage across each battery cell, the voltage drop and therefore the contact failure can be detected. BMS circuits for individual battery cells are known that have the ability to monitor cell health and contact failures at the contact joints. However, when battery cells are connected in series, or when modules or groups of battery cells are connected in series, it is not possible to measure the voltage drop at the connection joint using the existing BMS circuitry of the battery pack. Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, there is a need in the art for a system for diagnosing at least one loose contact in a battery pack, and a method thereof that addresses at least the aforementioned problems and limitations. [Means for solving the problem]

[0008] In one aspect, the present invention is directed to a system for diagnosing at least one contact failure 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 a preceding cell group, and the second contact terminal of the reference cell group is connected to the first contact terminal of a succeeding cell group. The system for diagnosing at least one contact failure 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 communicate the measured current to the master control unit. In one embodiment, the slave control unit of the reference cell group is adapted to measure a voltage drop across its first contact terminal and the second contact terminal of the preceding cell group, and a voltage drop across its second contact terminal and the first contact terminal of the succeeding cell group. In another embodiment, the slave control unit of the reference cell group is adapted to measure a voltage drop across its first contact terminal and a last battery cell of the preceding cell group and a voltage drop across its second contact terminal and a first battery cell of the succeeding cell group. The slave control unit of the reference cell group is further adapted to transmit the measured voltage drops to the master control unit. In one embodiment, the master control unit is adapted to determine a resistance between the first contact terminal of the reference cell group and a second contact terminal of the preceding cell group and / or between the second contact terminal of the reference cell group and a first contact terminal of the succeeding cell group based on the measured voltage drops received from the slave control units and the measured currents received from the current sensors.In another embodiment, the master control unit is adapted to determine a resistance between a first contact terminal of the reference cell group and a last battery cell of a preceding cell group and / or a resistance between a second contact terminal of the reference cell group and a first battery cell of a succeeding cell group based on the measured voltage drop received from the slave control unit and the measured current received from the current sensor, and the master control unit generates and communicates an alert indicating at least one contact failure if at least one of the determined resistances is greater than a predetermined first threshold value.

[0009] In one embodiment, the warning generated and transmitted by the master control unit indicating at least one contact failure includes information about the contact terminal where the contact failure occurred.

[0010] In another embodiment, the slave control unit of the reference cell group is adapted to measure a voltage drop across each battery cell of the reference cell group and communicate the measured voltage drop to the master control unit. In one 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. The master control unit generates and communicates the warning indicating at least one loose contact and the location of the loose contact if any of the determined resistances is greater than a predetermined second threshold value.

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

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

[0013] In another aspect, the present invention is directed to a method for diagnosing at least one contact failure 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 a preceding cell group, and the second contact terminal of the reference cell group is connected to the first contact terminal of a succeeding cell group. The method for diagnosing at least one contact failure in the battery pack includes measuring a current flowing through the reference cell group with a current sensor of the reference cell group and transmitting the measured current to a master control unit. In one embodiment, the method includes measuring, with a slave control unit of the reference cell group, a voltage drop across the first contact terminal of the reference cell group and the second contact terminal of the preceding cell group, and a voltage drop across the second contact terminal of the reference cell group and the first contact terminal of the succeeding cell group. In another embodiment, a method includes measuring, by a slave control unit of the reference cell group, a voltage drop across a first contact terminal of the reference cell group and a last battery cell of the preceding cell group and a voltage drop across a second contact terminal of the reference cell group and a first battery cell of the succeeding cell group. The method includes transmitting, by the slave control unit of the reference cell group, the measured voltage drops to a master control unit. The method further includes determining, by the master control unit, a resistance between the first contact terminal of the reference cell group and a second contact terminal of the preceding cell group and a resistance between the second contact terminal of the reference cell group and a first contact terminal of the succeeding cell group based on the measured voltage drops received from the slave control unit and the measured current received from the current sensor.In another embodiment, the method includes determining, by the master control unit, a resistance between a first contact terminal of the reference cell group and a last battery cell of the preceding cell group and a resistance between a second contact terminal of the reference cell group and a first battery cell of the succeeding cell group based on a measured voltage drop received from the slave control unit and a measured current received from the current sensor, and generating and transmitting, by the master control unit, an alert indicating at least one contact failure if at least one of the determined resistances is greater than a predetermined first threshold value.

[0014] In one embodiment, the method includes measuring, by a slave control unit of the reference cell group, a voltage drop across each battery cell of the reference cell group and communicating the measured voltage drops by the slave control unit of the reference cell group to a master control unit. The method further includes determining, by the master control unit, a resistance between each battery cell of the reference cell group based on the measured voltage drops received from the slave control units and the measured currents received from the current sensors, and generating and communicating, by the master control unit, the warning indicating at least one loose contact if any of the determined resistances is greater than a predetermined second threshold value.

[0015] Reference will now be made to embodiments of the invention, examples of which may be illustrated in the accompanying drawings. These drawings are intended to be illustrative, not limiting. While the invention will generally be described in the context of these embodiments, it will be understood that it is not intended that the invention be limited in scope to these particular embodiments. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a block diagram of an exemplary system for diagnosing at least one loose contact in a battery pack, in accordance with one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram of an exemplary reference cell group of a system for diagnosing at least one loose contact in a battery pack, in accordance with an embodiment of the present invention. [Figure 3] 1 is a schematic diagram of two cell groups of a system for diagnosing at least one loose contact in a battery pack according to a first embodiment of the present invention; [Figure 4] FIG. 10 is a schematic diagram of two cell groups of a system for diagnosing at least one loose contact in a battery pack according to a second embodiment of the present invention. [Figure 5] 1 illustrates a method for diagnosing at least one loose contact in a battery pack according to a first embodiment of the present invention. [Figure 6] 10A and 10B illustrate another method for diagnosing at least one loose contact in a battery pack according to a second embodiment of the present invention. [Figure 7] 1 is 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; [Figure 8] FIG. 10 is 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. [Figure 9] FIG. 10 illustrates another method for diagnosing at least one loose contact in a battery pack, according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] Various features and embodiments of the invention herein will be appreciated from the following further description thereof, as set forth below. In the exemplary embodiments that follow, the battery pack is shown as being comprised of series-connected cell groups. However, the disclosure herein may be applied to any type of battery pack that can accommodate the present subject matter without voiding the scope of the invention.

[0018] The present invention relates generally to battery packs, and more particularly to a system and method for diagnosing at least one loose contact in a battery pack.

[0019] FIG. 1 illustrates a block diagram of an exemplary system 100 for diagnosing at least one loose contact in a battery pack 10, in accordance with one embodiment of the present invention. The battery pack 10 includes a plurality of cell groups 110. In one embodiment, each cell group 110 is an individual battery module. In another embodiment, each cell group 110 is a group of cells within 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 one positive terminal and one negative terminal. The battery cells 120 of each cell group 110 are electrically interconnected to each other 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 and communicatively interconnected to each other. For purposes of illustration, the cell groups 110 are referred to as a reference cell group 110. X The reference cell group 110 is selected as X can be any cell group 110. X The cell group 110 preceding X-1 , 110 X-2 and the reference cell group 110 X The cell group 110 following 110 X+1 , 110 X+2 The system 100 includes a master control unit 140, a current sensor 150, and a slave control unit 160. Each of the plurality of cell groups 110 is provided with one current sensor 150. The reference cell group 110 X The current sensor 150 of the reference cell group 110 X and communicating the measured current to the master control unit 140. In one embodiment, a single current sensor 150 may be employed for all cell groups 110.

[0020] FIG. 2 illustrates an exemplary reference cell group 110 of a system 100 for diagnosing at least one loose contact in a battery pack 10, in accordance with one embodiment of the present invention. X 1 shows a schematic diagram of a reference cell group 110. Each 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 of the preceding cell group 110 X-1 The reference cell group 110 is connected to the second contact terminal 114 of the reference cell group 110. X The second contact terminal 114 of the subsequent cell group 110 X+1 1. The cell groups 110 in the battery pack 10 are therefore connected in series. Each of the multiple cell groups 110 is provided with one slave control unit 160. In one embodiment, each slave control unit 160 comprises a BMS (Battery Management System) ASIC (Application Specific Integrated Circuit). In another embodiment, the slave control unit 160 comprises a CMU (Battery Cell Management Unit). The slave control unit 160 can measure the voltage across each of the battery cells 120 in the cell group 110. The slave control unit 160 can measure the voltage across the positive terminal of each of the battery cells 120 in the 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 cell group 110, and the second contact terminal 114 is connected to or is the same as the positive terminal of the last battery cell 1201 in the cell group 110. N5 and 6 , the slave control unit 160 knows the voltage drops at the hardwired points and the pin numbers of the slave control unit 160 that are connected to or the same as the negative terminals of the battery cells 120. Through the hardwired connections between the positive and negative terminals of the battery cells 120 and the pins of the slave control unit 160, the slave control unit 160 senses the voltage available at each of the hardwired points, and based on the sensed voltages, the slave control unit 160 calculates the voltage drops across the hardwired points. In one embodiment, the slave control unit 160 may send all of the sensed voltages to the master control unit 140, which calculates the voltage drops across these hardwired points. Also, in one embodiment, the slave control unit 160 passes the voltage drops to the master control unit 140 along with the pin numbers across which the voltage drops were determined. Thus, the master control unit 140 knows the voltage drops at the hardwired points and the identifier of the slave control unit 160 that sent the voltage drops to identify the location of the loose contact, based on the methods described in FIGS. 5 and 6 .

[0021] FIG. 3 illustrates two cell groups 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 invention. X and 110 X-1 In the illustrated embodiment, a reference cell group 110 X The slave control unit 160 of the first contact terminal 112 and the preceding cell group 110 X-1 The reference cell group 110 is adapted to measure the voltage drop across the second contact terminal 114 of the reference cell group 110. X The slave control unit 160 of the second contact terminal 114 and the subsequent cell group 110 X+1 In the first embodiment, the slave control unit 160 is further adapted to measure a voltage drop across the first contact terminals 112 of the reference cell group 110. X The first contact terminal 112 and the preceding cell group 110 X-1 and / or the reference cell group 110 XThe second contact terminal 114 and the subsequent cell group 110 X+1 1. The input pin is wired to connect with the first contact terminal 112 of the input terminal.

[0022] FIG. 4 illustrates two exemplary reference cell groups 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 invention. X and 110 X-1 In the illustrated embodiment, a reference cell group 110 X The slave control unit 160 of the first contact terminal 112 and the preceding cell group 110 X-1 Last battery cell 120 N The reference cell group 110 is adapted to measure the voltage drop across the reference cell group 110. X The slave control unit 160 of the second contact terminal 114 and the subsequent cell group 110 X+1 In the second embodiment, the slave control unit 160 is further adapted to measure the voltage drop across the first battery cell 1201 of the reference cell group 110 and the first battery cell 1202 of the reference cell group 110. X The first contact terminal 112 and the preceding cell group 110 X-1 Last battery cell 120 N and / or the reference cell group 110 X The second contact terminal 114 and the subsequent cell group 110 X+1 12. The first battery cell 1201 has an input pin hardwired to connect with the first battery cell 1201.

[0023] Referring to FIGS. 3 and 4, the reference cell group 110 X The slave control unit 160 of the reference cell group 110 XThe reference cell group 110 is adapted to measure the voltage drop across each battery cell 120 in the reference cell group 110. In one embodiment, the voltage measurement is performed by tapping the corresponding first contact terminal 112 or second contact terminal 114 of the reference cell group 110, or the corresponding positive or negative terminal of each battery cell 120 as the case may be, to a voltage 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 cell 120 or the cell group 110 as the case may be. For this purpose, existing elements of the BMS of the battery pack 10 can be used without adding any extra circuitry. In one embodiment, one of many existing cell voltage monitoring channels of the BMS ASIC of the battery pack 10 can be used to detect the voltage drop. These measurements are fairly accurate, with an error of less than ±2 mV, and are faster, detecting within approximately 100 milliseconds. The voltage drop measurement is not affected by temperature fluctuations within the battery pack 10.

[0024] Reference Cell Group 110 XThe slave control units 160 of the plurality of cell groups 110 are further adapted to communicate the measured voltage drops to the master control unit 140. In one 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 enabled by 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 temperatures 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 provided at one or both terminals of one or more of the battery cells 120 of the corresponding cell group 110. Thus, the temperature sensors can measure temperatures at the positive and negative terminals of the battery cells 110 of each cell group 110. The use of typical analog circuitry to accurately detect voltage drops (on the order of mV) is limited due to the limited accuracy of measuring the high voltages at the first and second contact terminals 112, 114 of the cell group 110 to arrive at their difference. Therefore, in one embodiment, a temperature sensor 170 is placed on or near the first and second contact terminals 112, 114 to measure temperature changes. In another embodiment, a temperature sensor placed near the positive and negative terminals of the multiple battery cells 120 helps to more accurately measure the voltage drops between the battery cells.

[0025] 5 illustrates a method 500 for diagnosing at least one loose contact in a battery pack 10 according to a first embodiment of the present invention. In the illustrated embodiment, the reference cell group 110 X The slave control unit 160 of the first contact terminal 112 and the preceding cell group 110 X-1 The voltage drop across the second contact terminal 114 of the reference cell group 110 is measured 508. X The slave control unit 160 also has its second contact terminal 114 and the subsequent cell group 110 X+1The voltage drop across the first contact terminal 112 of the cell group 110 is measured 510. To perform this measurement, X 3 and 5, the reference cell group 110 X The current sensor 150 of the reference cell group 110 X Measure 504 the current flowing through the reference cell group 110 X The current sensor 150 of the reference cell group 110 further communicates 506 the measured current to the master control unit 140. The method 500 communicates 506 the measured voltage drop to the master control unit 140. X In one embodiment, the master control unit 140 determines whether the reference cell group 110 is a 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 and the preceding cell group 110 X-1 In another embodiment, the master control unit 140 determines 514 the resistance between the second contact terminal 114 of 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 and the subsequent cell group 110 X+1 and the first contact terminal 112. If any of the one or more resistances determined by the master control unit 140 is greater than a predetermined first threshold value, the master control unit 140 generates and communicates 518 a warning indicating at least one poor contact.

[0026] 6 illustrates another method 500 for diagnosing at least one loose contact in a battery pack 10 according to a second embodiment of the present invention. In the illustrated embodiment, the reference cell group 110 X The slave control unit 160 of the first contact terminal 112 and the preceding cell group 110 X-1 Last battery cell 120 NMeasure the voltage drop across the reference cell group 110. X The slave control unit 160 also has its second contact terminal 114 and the subsequent cell group 110 X+1 The voltage drop across the first battery cell 1201 of the cell group 110 is measured 524. X 4 and 6, the reference cell group 110 X The current sensor 150 of the reference cell group 110 X Measure 504 the current flowing through the reference cell group 110 X The current sensor 150 of the reference cell group 110 further communicates 506 the measured current to the master control unit 140. The method 500 communicates 506 the measured voltage drop to the master control unit 140. X In one embodiment, the master control unit 140 determines whether the reference cell group 110 is a 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 and the preceding cell group 110 X-1 Last battery cell 120 N In another embodiment, the master control unit 140 determines 526 the resistance between the reference cell group 110 and 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 and the subsequent cell group 110 X+1 and the first battery cell 1201. If any of the one or more resistances determined by the master control unit 140 is greater than a predetermined first threshold value, the master control unit 140 generates and communicates 518 a warning indicating at least one poor contact.

[0027] As the contact failure at each terminal worsens, i.e., as the contact at the terminal becomes looser or the distance between the electrical connector and the respective terminal increases, the resistance at these points also increases accordingly. In one embodiment, the alert generated and transmitted by the master control unit 140 includes information about the contact terminals 112, 114 where the contact failure occurred. The alert may be displayed on a display device 180 (shown in FIG. 1 ) or on a screen visible to a user of the battery-using device, and / or may be transmitted directly to a service station. Display devices include an instrument cluster in a vehicle employing the battery pack 10, a personal mobile device, a personal computer, a dedicated screen on the battery pack 10, a computing device at a service station, etc. The alert may also be transmitted to a BMS or ECU (electronic control unit), which may power down the faulty cell group 110. In the embodiment shown in FIG. 6 , the master control unit 140 detects the reference cell group 110 X The first contact terminal 112 and the preceding cell group 110 X-1 Last battery cell 120 N and / or the voltage drop across the reference cell group 110 X The second contact terminal 114 and the subsequent cell group 110 X+1 The voltage drop across the first battery cell 1201 and the second battery cell 1202 is calculated by dividing the voltage drop across each of the first battery cell 1201, 120 N The voltages of the respective battery cells 1201 and 120 N Since the individual voltages of the connectors are also known to the master control unit 140, the master control unit 140 can estimate and locate the voltage drop across the connector.

[0028] 7 shows 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. To perform this measurement, a group of cells 110 X can be connected as shown in FIG. XThe current sensor 150 of the reference cell group 110 X Measure 504 the current flowing through the reference cell group 110 X The current sensor 150 of the reference cell group 110 further communicates 506 the measured current to the master control unit 140. The method 500 communicates 506 the measured voltage drop to the master control unit 140. X In one embodiment, the master control unit 140 determines whether the reference cell group 110 is a 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 and the preceding cell group 110 X-1 Last battery cell 120 N In another embodiment, the master control unit 140 determines 526 the resistance between the reference cell group 110 and 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 and the subsequent cell group 110 X+1 The master control unit 140 determines 528 the resistance between the first battery cell 1201 and the terminal. If any of the one or more resistances determined by the master control unit 140 is greater than a predetermined first threshold value, the master control unit 140 generates and transmits 518 a warning indicating at least one contact fault, which is transmitted to other ECUs via the CAN bus. In one embodiment, the resistance is determined again by the master control unit 140 even after the warning is transmitted. In another embodiment, if any of the resistances determined by the master control unit 140 is less than a predetermined first threshold value, all faults associated with the terminal are eliminated and the resistance is determined again by the master control unit 140.

[0029] 8 shows 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. To perform this measurement, a group of cells 110 Xcan be connected as shown in FIG. X The current sensor 150 of the reference cell group 110 X Measure 504 the current flowing through the reference cell group 110 X The current sensor 150 of the reference cell group 110 further communicates 506 the measured current to the master control unit 140. The method 500 communicates 506 the measured voltage drop to the master control unit 140. X In one embodiment, the master control unit 140 determines whether the reference cell group 110 is a 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 and the preceding cell group 110 X-1 Last battery cell 120 N In another embodiment, the master control unit 140 determines 526 the resistance between the reference cell group 110 and 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 and the subsequent cell group 110 X+1 The master control unit 140 determines 528 the resistance between the first battery cell 1201 and the terminal. If any of the one or more resistances determined by the master control unit 140 is greater than a predetermined first threshold value, the master control unit 140 generates and transmits 518 a warning indicating at least one contact fault. In one embodiment, the resistance is again determined by the master control unit 140 after the warning is transmitted. In another embodiment, if any of the resistances determined by the master control unit 140 is less than a predetermined first threshold value, all faults associated with the terminal are eliminated and the resistance is again determined by the master control unit 140.

[0030] 9 illustrates a method 500 for diagnosing at least one loose contact in a battery pack 10 according to a third embodiment of the present invention. In the illustrated embodiment, the reference cell group 110 X The slave control unit 160 of the reference cell group 110 X Measure 532 the voltage drop across each battery cell 120 of the reference cell group 110 X The slave control unit 160 further communicates 512 the measured voltage drop to the master control unit 140. The master control unit 140 determines 513 the voltage drop of 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 determining 536 the resistance between each of the battery cells 120. Method 500 includes generating 518 and transmitting 518 said warning by master control unit 140 indicating at least one loose contact if any of the determined resistances is greater than a predetermined second threshold value. The first threshold value and the second threshold value may be preset to different values based on the nature and type of battery pack 10 into which system 100 and method 500 are incorporated. In one embodiment, the first threshold value and the second threshold value are equal.

[0031] Advantageously, the present invention provides a system and method for diagnosing at least one loose contact in a battery pack. The battery pack finds application in high-voltage systems, such as vehicles, where a BMS / slave control unit resides with the battery pack and a master control unit may be one of the vehicle's control units. The system and method rapidly determine the loose contact and its location in real time to avoid catastrophic damage to the high-voltage system, such as a vehicle. Each battery cell and terminal is hard-wired to a slave control unit, and the slave control unit with a voltage drop passing between its pins is sensed, so the location of the loose contact can be accurately determined. Thus, the master control unit knows the voltage drops and their corresponding locations. The claimed system and method for diagnosing at least one loose contact in a battery pack described above is not routine, conventional, or well-understood in the art, because the claimed system and method for diagnosing at least one loose contact in a battery pack enables the following solutions to existing problems in the prior art: By adopting the above system and method, it is possible to accurately measure contact failures between individual battery cells and between cell groups or modules with minor modifications to the existing hardware of the battery pack. It is simple and cost-effective to implement in the battery pack. It also does not consume much space and is light in weight. Furthermore, terminals electrically connected using bus bars, which may loosen under vibration, can be monitored by the given system and method. It also enables early and timely detection of contact failures and accurate detection of contact loss. No temperature sensor is required, therefore the installation cost is low.

[0032] While the present invention has been described with respect to several embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the scope of the invention, which is defined in the claims that follow. [Explanation of symbols]

[0033] 10 Battery pack 100 System for diagnosing poor contacts in a battery pack 110 Multiple Cell Groups 110 X Reference Cell Group 110 X-1 Cell group preceding the reference cell group 110 X+1 Cell groups following the reference cell group 112 first contact terminal of cell group 114 Cell group second contact terminal 120 Multiple Battery Cells 140 Master Control Unit 150 Current Sensor 160 Slave Control Unit 170 Multiple Temperature Sensors 180 A display device for displaying generated warnings

Claims

1. A system (100) for diagnosing at least one contact failure 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), and a reference cell group (110) Ｘ The first contact terminal (112) of the preceding cell group (110) Ｘ－１ ) and connected to the second contact terminal (114) of the reference cell group (110 Ｘ The second contact terminal (114) of the subsequent cell group (110) Ｘ＋１ ) connected to the first contact terminal (112) of the system (100), a master control unit (140); a current sensor (150) for each of the plurality of cell groups (110), the current sensor (150) for the reference cell group (110); Ｘ The current sensor (150) of the reference cell group (110 Ｘ a current sensor (150) configured to measure a current flowing through the power supply (110) and to communicate the measured current to the master control unit (140); a slave control unit (160) for each of the plurality of cell groups (110), the slave control unit (160) controlling the reference cell group (110); Ｘ The slave control unit (160) of The first contact terminal (112) and the preceding cell group (110) Ｘ－１ ) and its first contact terminal (112) and the preceding cell group (110) Ｘ－１ ) last battery cell (120 Ｎ ) and the voltage drop across the The second contact terminal (114) and the subsequent cell group (110 Ｘ＋１ ) and its second contact terminal (114) and the subsequent cell group (110) Ｘ＋１ ) a first battery cell (120 １ ) and the voltage drop across the transmitting the measured voltage drop to the master control unit (140); a slave control unit (160) configured to: Including, The master control unit (140) The reference cell group (110) is controlled 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 preceding cell group (110) Ｘ－１ determining the resistance between the second contact terminal (114) of the Based on the measured voltage drop received from the slave control unit (160) and the measured current received from the current sensor (150), the reference cell group (110) Ｘ ) and the subsequent cell group (110 Ｘ＋１ determining the resistance between the first contact terminal (112) of the or based on the measured voltage drop received from the slave control unit (160) and the measured current received from the current sensor (150), the reference cell group (110) Ｘ ) and the preceding cell group (110) Ｘ－１ ) the last battery cell (120 Ｎ ) and determining a resistance between the reference cell group (110) and 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 subsequent cell group (110 Ｘ＋１ ) the first battery cell (120 １ ) and the voltage drop across its second contact terminal (114); generating and communicating on a display device (180) a warning indicating at least one poor contact if at least one of the determined resistances is greater than a predetermined first threshold value; The system (100) is configured to:

2. 2. The system (100) for diagnosing at least one contact failure in a battery pack (10) as described in claim 1, wherein the warning generated and transmitted by the master control unit (140) includes information about the contact terminal (112, 114) where the contact failure occurred.

3. The reference cell group (110 Ｘ The slave control unit (160) of the reference cell group (110 Ｘ 2. The system for diagnosing at least one loose contact in a battery pack as recited in claim 1, configured to measure a voltage drop across each battery cell of a battery pack; and communicate the measured voltage drop to the master control unit.

4. The master control unit (140) determines 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 4. The system for diagnosing at least one loose contact in a battery pack according to claim 3, further configured to: determine a resistance between each battery cell of a battery pack; and generate and communicate the warning indicating at least one loose contact and a location of the loose contact if any of the determined resistances is greater than a predetermined second threshold value.

5. 2. The system for diagnosing at least one contact failure in a battery pack according to claim 1, wherein each of the plurality of cell groups includes a plurality of temperature sensors configured to measure temperatures at the first contact terminal and the second contact terminal of the corresponding cell group and at one or both terminals of one or more of the battery cells of the corresponding cell group.

6. 2. The system for diagnosing at least one loose contact in a battery pack as recited in claim 1, wherein the slave control units of the plurality of cell groups are configured to communicate with each other and with the master control unit.

7. A method (500) for diagnosing at least one contact failure 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), and a reference cell group (110). Ｘ The first contact terminal (112) of the preceding cell group (110) Ｘ－１ ) and connected to the second contact terminal (114) of the reference cell group (110 Ｘ The second contact terminal (114) of the subsequent cell group (110) Ｘ＋１ ) to the first contact terminal (112), and the method (500) comprises: The reference cell group (110 Ｘ ) the current flowing through the reference cell group (110 Ｘ ) by a current sensor (150) and transmitting (506) said measured current to a master control unit (140); The reference cell group (110 Ｘ ) and the preceding cell group (110) Ｘ－１ a voltage drop across the second contact terminal (114) of the reference cell group (110) and the reference cell group (110) Ｘ ) and the preceding cell group (110) Ｘ－１ ) last battery cell (120 Ｎ ) and the voltage drop across the reference cell group (110 Ｘ measuring (508, 522) by a slave control unit (160) of the The reference cell group (110 Ｘ ) and the subsequent cell group (110 Ｘ＋１ a voltage drop across the first contact terminal (112) of the reference cell group (110) and the reference cell group (110) Ｘ ) and the subsequent cell group (110 Ｘ＋１ ) a first battery cell (120 １ ) and the voltage drop across the reference cell group (110 Ｘ measuring (510, 524) by said slave control unit (160); The measured voltage drop is transmitted to the master control unit (140) and the reference cell group (110 Ｘ ) transmitting (512) by said slave control unit (160); 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 preceding cell group (110) Ｘ－１ determining (514) by the master control unit (140) a resistance between the first contact terminal (114) and the second contact terminal (114); 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 subsequent cell group (110 Ｘ＋１ determining (516) by the master control unit (140) a resistance between the first contact terminal (112) of the 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 preceding cell group (110) Ｘ－１ ) the last battery cell (120 Ｎ ) by said master control unit (140); 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 subsequent cell group (110 Ｘ＋１ ) the first battery cell (120 １ ) by said master control unit (140); generating (518) and transmitting (518) by the master control unit (140) an alarm indicating at least one poor contact if at least one of the determined resistances is greater than a predetermined first threshold value; A method (500) comprising:

8. The reference cell group (110 Ｘ ) the voltage drop across each battery cell (120) of the reference cell group (110 Ｘ ) by the slave control unit (160), and transmitting the measured voltage drop to the master control unit (140) for the reference cell group (110). Ｘ and communicating (512) by said slave control unit (160) of said battery pack (10).

9. Based on the measured voltage drop received from the slave control unit (160) and the measured current received from the current sensor (150), the reference cell group (110) Ｘ 10. The method for diagnosing at least one loose contact in a battery pack as recited in claim 8, further comprising: determining, by the master control unit, a resistance between each battery cell of a battery pack; and generating, by the master control unit, and transmitting, if any of the determined resistances is greater than a predetermined second threshold value, the warning indicating at least one loose contact.

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