[0001] The present subject matter described herein, relates to an electric vehicle. More particularly, the present subject matter relates to a system and a method for detecting welding, abnormality of all passive protection devices including contactors and fuse of a traction battery pack while opening the contactors and closing the contactors during turning ON and turning OFF of the electric vehicle, respectively. Further, the system and the method prohibits starting of the electric vehicle upon detection of the welding and the abnormality of any of the contactor.
BACKGROUND
[0002] Background description includes information that may be useful in understanding the present invention.
[0003] In electric vehicles, a traction battery pack is provided which is a primary energy source for providing energy for traction of vehicle. The traction battery pack has a battery string comprising of plurality of battery modules connected either in series or in parallel or in any combination with each other. A plurality of cells combined with each other to form a battery module and a plurality of battery modules combined with each other to form a battery pack or a traction battery pack. The traction battery pack generates a high voltage (HV) for traction of an electric motor for traction of the electric vehicle. An inverter is provided in between the traction battery pack and the electric motor for conversion of direct current (DC) from the traction battery pack into alternate current (AC) for drive of the AC motor for traction. The traction battery pack can be controlled by the electronic modules, such as electronic control unit (ECU) or vehicle control unit (VCU) from outside the traction battery pack, or can be controlled by electronic module, such as battery management system (BMS) from inside the traction battery pack. The electronic module operates passive protection devices to draw current from the traction battery pack. These electronic modules are also responsible for implementing various battery state estimations, such as state of charge (SOC), state of health (SOH), state of function (SOF), state of power (SOP), etc.
[0004] A master battery management system (BMS) is provided to communicate with a plurality of slave BMS of the plurality of battery modules to collect the cell data and optionally transmit the same to vehicle control unit (VCU) for further analysis and protection functions. Further, the protection functions are controlled by the VCU only, master BMS only, or in combination by the VCU and the master BMS.
[0005] The traction battery pack supplies high current for traction of vehicle. The VCU or the master BMS controls the output of the traction battery pack by controlling the open and close state of the contactors, such as positive contactor and negative contactor.
[0006] In the circuitry of the traction battery pack, a positive contactor is provided in series between a positive terminal (HV+) or electrodes of the traction battery and the inverter, and a negative contactor is connected in series between negative terminal (HV-) or electrodes of the traction battery and the inverter. In addition, a pre-charge contactor, with a resistor in series, is connected in parallel with the positive contactor (HV+).
[0007] The inverter operates semi-conductor devices and switches ON and OFF at very high frequencies, which would tend to put very high transience on the voltage bus. These high transience’s can cause damage to the battery pack. To avoid the damage, the inverter also has large capacitors inside of it to smooth out these transients so that when the motor is operating, the battery pack does not experience this high level of noise, caused by the load that it is connected to.
[0008] When the inverter whose capacitor is initially at zero volts charged, and motor is connected with the battery pack by connecting the positive and negative terminal. An enormous amount of current would flow out of the battery pack instantly to charge the capacitor. This enormous amount of electrical current has the potential to cause arcing inside the contactors and to possibly weld them closed. And after that point, the contactors would never be able to physically open again.
[0009] Therefore, to avoid welding of contactors due to high inrush current due to closing of positive and negative contactor, first the pre-charge is closed with the negative contactor to charge the capacitor equivalent to voltage of the traction battery pack.
[0010] Technical Problem: However, contactors may be welded at a contact due to an arc struck in the contact upon opening or closing operation or due to aging, and, if the contactors of both of the positive electrode and the negative electrode are welded, the traction battery pack and the inverter cannot be electrically separated which is hazardous for traction battery pack as well as for users or operators of electric vehicle.
[0011] Therefore, a technique is required that can detect which contactor is welded.
[0012] Existing technologies do not detect weld condition of all the contactors, such as positive contactor, negative contactor, pre-charge, fuse. Existing technologies detects either pre-charge or positive contact is welded or negative contactor is welded. Existing technologies do not detect welding state of pre-charge and positive contactor separately. Further, separate abnormality of the contactors is also not detected.
[0013] Further existing technologies required dedicated detection circuitry to determine welding and abnormality status of the contactors. Some existing technologies required boost circuit for charging the capacitor voltage before determining the weld conditions.
[0014] Therefore, there is a need for a system and a method that detects the weld condition as well as abnormality condition of all contactors either connected on positive side or on negative side along with fuse blown condition before turning on the electric vehicle and before turning off the electric vehicle.
OBJECTS OF THE DISCLOSURE
[0015] Some of the objects of the present disclosure, which at least one embodiment herein satisfy, are listed herein below.
[0016] The principal object of the present subject matter is to provide a system and a method that detects weld and abnormality condition of all contactors, such as positive, negative, pre-charge, and fuse condition.
[0017] Another object of the present subject matter is to provide a system and a method for detecting weld and abnormality condition of the contactors without addition of any boost circuit or addition of auxiliary voltage.
[0018] Another object of the present subject matter is to provide a system and a method for detecting weld and abnormality condition of the contactors before turning on and turning off the electric vehicle.
[0019] These and other objects and advantages will become more apparent when reference is made to the following description and accompanying drawings.
SUMMARY
[0020] This summary is provided to introduce concepts related to a system and a method for detecting weld condition of any of contactor either on positive side or on negative side. The concepts are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
[0021] In an embodiment, the present subject matter relates to a traction battery pack of an electric vehicle. The traction battery pack comprises a battery string coupled with a plurality of slave BMS to supply high voltage (HV); a master battery management system (BMS) coupled with the plurality of slave BMS, the master BMS having a controller coupled with a voltage measuring circuit and a switching circuit to detect weld condition of a positive contactor, a negative contactor, and a pre-charge contactor of the battery string before turning ON the electric vehicle; the voltage measuring circuit coupled with the switching circuit to measure voltage (V1AB) between terminal (B) and terminal (A), voltage (V2AC) between terminal (A) and terminal (C), and voltage (Vinv) at an inverter or load; the controller determines that the positive contactor or the pre-charge contactor is not welded when the voltage (V1AB) is less than or equal to a threshold voltage value (Vth); and the controller closes the pre-charge contactor and measures the voltage (V2AC) after a second time (t2) to determine that the negative contactor is welded when the voltage (V2AC) is greater than or equal to the threshold voltage value (Vth).
[0022] In an aspect, the controller closes the negative contactor and measures the voltage (V1AB), the voltage (V2AC), and the voltage (Vinv); and determines that a fuse is blown when the voltage (V2AC) is not equal to the voltage (Vinv).
[0023] In an aspect, the controller turns ON the load and measures the voltage (V1AB) after sixth time (t6); determines that the pre-charge contactor is welded when the voltage (V1AB) is less than a threshold voltage (Vth1) of the battery string; and determines that the positive contactor is welded when the voltage (V1AB) is greater than the threshold voltage (Vth1) of the battery string.

[0024] In an aspect, the controller closes the negative contactor and measures the voltage (V1AB) and the voltage (V2AC); determines that the negative contactor is abnormal when the voltage (V1AB) is not equal to the voltage (V2AC).
[0025] In an aspect, the controller closes the pre-charge contactor and measures the voltage (V1AB) after a first time (t1) to determine that the pre-charge contactor is normal when the voltage (V1Ab) is greater than or equal to the threshold voltage value (Vth); closes the negative contactor and measures the voltage (V2AC) after a third time (t3) to determine that negative contactor is normal when the voltage (V2AC) is greater than or equal to the threshold voltage value (Vth); and closes the positive contactor and opens the pre-charge contactor and measures the voltage (V2AC) and voltage of inverter (Vinv) after a fourth time (t4) to: determine that positive contactor is normal when the voltage (V2AC) is greater to the threshold voltage value (Vth1) of the traction battery pack; and determine that a fuse is normal when the voltage (V2AC) is equal to the voltage of inverter (Vinv).
[0026] In an embodiment of the present traction battery pack of an electric vehicle. The battery string coupled with a plurality of slave BMS to supply high voltage (HV); a master battery management system (BMS) coupled with the plurality of slave BMS, the master BMS having a controller coupled with a voltage measuring circuit and a switching circuit to detect weld condition of a positive contactor, a negative contactor, and a pre-charge contactor of the battery string before turning OFF the electric vehicle; the voltage measuring circuit coupled with the switching circuit to measure voltage (V1AB) between terminal (B) and terminal (A), voltage (V2AC) between terminal (A) and terminal (C), and voltage (Vinv) at an inverter or load; the controller determines that a fuse is blown when the voltage (V1AB) is equal to the voltage (V2AC) and the voltage (V2AC) is not equal to voltage (Vinv) of the inverter; the controller opens the positive contactor and measures the voltage (V1AB) after time (t5) to determine that the pre-charge contactor or the positive contactor is welded when the voltage (V1AB) is greater or equal to a threshold voltage value (Vth).

[0027] In an aspect, the controller turns on the load and measure the voltage (V1AB) after time (t6); determines that the pre-charge contactor is welded when the voltage (V1AB) is less than a threshold voltage (Vth1) of the battery string; and determines that the positive contactor is welded when the voltage (V1AB) is greater than the threshold voltage (Vth1) of the battery string.
[0028] In aspect, the controller opens the negative contactor and measures the voltage (V1AB) and the voltage (V2AC); and determines that the negative contactor is welded when the voltage (V1AB) is equal to the voltage (V2AC).
[0029] In an aspect, the controller determines that the negative contactor is abnormal when the voltage (V1AB) is not equal to the voltage (V2AC); and opens the positive contactor and the negative contactor.
[0030] In an aspect, the controller opens the positive contactor and measures the voltage (V1AB) after time (t5) to determine that the pre-charge contactor and the positive contactor is normal when the voltage (V1AB) is less than the threshold voltage value (Vth).
[0031] In an embodiment of the present subject matter, a method for detecting weld and abnormality condition of a positive contactor, a negative contactor, a pre-charge contactor and blown condition of a fuse of a traction battery pack during turning ON of an electric vehicle. The method comprising measuring a voltage (V1AB) across terminal (A) and terminal (B) by a voltage measuring circuit; comparing the voltage (V1AB) with a threshold voltage value (Vth); determining that the positive contactor or the pre-charge contactor is welded when the voltage (V1AB) is greater than the threshold voltage value (Vth); closing the negative contactor and measuring the voltage (V1AB), a voltage (V2AC) across terminal (A) and terminal (C), and a voltage (Vinv) of an inverter; turning ON a load and measuring the voltage (V1AB) after sixth time (t6=2RC); determining that pre-charge contactor is welded when voltage (V1AB) is less than a threshold voltage (Vth1) of a battery string of the traction battery pack; and determining that the positive contactor is welded when the voltage (V1AB) is greater than the threshold voltage (Vth1) of the battery string;
[0032] In an aspect, the method includes closing the pre-charge contactor and measures the voltage (V2AC) after a second time (t2); and determining that the negative contactor (104) is welded when the voltage (V2AC) is greater than or equal to the threshold voltage value (Vth).
[0033] In an aspect, the method includes closing the negative contactor and measures the voltage (V2AC) after third time (t3); determining that the negative contactor is normal when the voltage (V2AC) is greater than or equal to the threshold voltage value (Vth).
[0034] In an aspect, the method includes closing the positive contactor and opening the pre-charge contactor and measuring the voltage (V2AC) and voltage of inverter (Vinv) after a fourth time (t4); determining that positive contactor is normal when the voltage (V2AC) is greater to the threshold voltage value (Vth1) of the traction battery pack; and determining that a fuse is normal when the voltage (V2AC) is equal to the voltage of inverter (Vinv).
[0035] In yet another embodiment of the present subject matter, the present subject matter relates to a method for detecting weld condition of a positive contactor, a negative contactor, a pre-charge contactor, and blown condition of a fuse of a traction battery pack during turning OFF of an electric vehicle. The method includes measuring a voltage (V1AB) across terminal (A) and terminal (B), a voltage (V2AC) across terminal (A) and terminal (C), a voltage (Vinv) of an inverter by a voltage measuring circuit provided in a master Battery Management System (BMS); opening the positive contactor and measuring the voltage (V1AB) after a fifth time (t5); and determining that the pre-charge contactor or the positive contactor is welded when the voltage (V1AB) is greater than or equal to a threshold voltage value (Vth).
[0036] In an aspect, the method includes turning ON the load and measuring the voltage (V1AB) after time (t6=2RC); and determining that the pre-charge contactor is welded when the voltage (V1AB) is less than a threshold voltage (Vth1) of a battery string of the traction battery pack; and determining that the positive contactor is welded when the voltage (V1AB) is greater than the threshold voltage (Vth1) of the battery string.
[0037] In an aspect, the method includes opening the negative contactor and measuring the voltage (V1AB) and the voltage (V2AC); and determining that the negative contactor is welded when the voltage (V1AB) is equal to the voltage (V2AC).
[0038] In an aspect, the method determining that the negative contactor is abnormal when the voltage (V1AB) is not equal to the voltage (V2AC); and opening the positive contactor and the negative contactor.
[0039] In an aspect, the method includes opening the positive contactor and measuring the voltage (V1AB) after the fifth time (t5); and determining that the pre-charge contactor and the positive contactor is normal when the voltage (V1AB) is less than the threshold voltage value (Vth).
[0040] In an aspect, the method includes determining that the fuse is blown when the voltage (V2AC) is not equal to the voltage (Vinv) of the inverter.
[0041] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.
BRIEF DESCRIPTION OF THE DRAWINGS
[0042] The illustrated embodiments of the subject matter will be understood by reference to the drawings, wherein like parts are designated by like numerals throughout. The following description is intended only by way of example, and simply illustrates certain selected embodiments of devices, systems, and methods that are consistent with the subject matter as claimed herein, wherein:
[0043] Fig. 1 illustrates architecture of traction battery pack with master battery management system (BMS) and a switching circuit, in accordance with an embodiment of the present subject matter; and
[0044] Fig. 2 illustrates time frame for opening and closing of pre-charge, negative, and positive contactor, in accordance with an embodiment of the present subject matter;
[0045] Fig. 3 illustrates a method for detecting weld condition and abnormality of all contactors before turning ON the electric vehicle, in accordance with an embodiment of the present subject matter; and
[0046] Fig. 4 illustrates a method for detecting weld condition and abnormality of all contactors before turning OFF the electric vehicle, in accordance with an embodiment of the present subject matter.
[0047] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAILED DESCRIPTION
[0048] The detailed description of various exemplary embodiments of the disclosure is described herein with reference to the accompanying drawings. It should be noted that the embodiments are described herein in such details as to clearly communicate the disclosure. However, the amount of details provided herein is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the present disclosure as defined by the appended claims.
[0049] It is also to be understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting principles, aspects, and embodiments of the present disclosure, as well as specific examples, are intended to encompass equivalents thereof.
[0050] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a",” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.
[0051] It should also be noted that in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may, in fact, be executed concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved.
[0052] In addition, the descriptions of "first", "second", “third”, and the like in the present invention are used for the purpose of description only, and are not to be construed as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Thus, features defining "first" and "second" may include at least one of the features, either explicitly or implicitly.
[0053] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, e.g., those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
[0054] Non-limiting Definitions
[0055] In the disclosure hereinafter, one or more terms are used to describe various aspects of the present disclosure. For a better understanding of the present disclosure, a few definitions are provided herein for better understanding of the present disclosure.
[0056] Master battery management system (BMS): A system which is any electronic system that manages a rechargeable battery (cell or battery pack), such as by protecting the battery from operating outside its safe operating area, monitoring its state, calculating secondary data, reporting that data, controlling its environment, authenticating it and / or balancing it.
[0057] Slave BMS: A system which is any electronic system that manages a plurality of cells in a battery module such as by detecting state of health (SOH), temperature, state of charge (SOC) condition, over-charge and over-discharge voltage conditions, and communicating the conditions of the plurality of cells to master BMS.
[0058] Welding of contactors: when a contactor such as a switch is fused or joined and does not open based on the control open command.
[0059] Abnormality of contactors: When the contactors are not closing based on the control close command.
[0060] Low voltage: Less than 60V
[0061] High voltage: 60V or more
[0062] Switching Circuit: It consists of resistors and MOSFETS which are controlled by master BMS. The purpose of switching circuit is to use only measurement channel in BMS to measure the two voltages by switching between point B and C.
[0063] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0064] Technical objective of the present subject matter is to detect welding of contactors of the traction battery pack during turning ON and turning OFF of the electric vehicle. Further, the present subject matter relates to a system and a method for prohibiting the start of the electric vehicle by turning OFF all the passive devices (e.g. contactors), PEM and auxiliary components.
[0065] The present subject matter can be implemented in any electric vehicle having traction battery pack. Further, the present subject matter overcomes all the technical problems as mentioned in the background section by providing a system, i.e., controller of the master BMS to detect weld condition of all contactors before turning ON and turning OFF of the electric vehicle.
[0066] Exemplary Implementations
[0067] To this, as shown in fig. 1, an architecture of a traction battery pack 100 for an electric vehicle is explained. The architecture of traction battery pack 100 comprises a master battery management system (BMS) 102 coupled with a plurality of slave BMS 101. The plurality of slave BMS 101 is coupled with a battery string 100a that supplies high voltage to a load. The master BMS 102 comprises a controller 102a having predefined logics to open and close high voltage contactors (HV+, HV-) based on the predefined sequence.
[0068] Each of the battery module in the battery string 100a is coupled with a slave BMS 101 and each of the slave BMS 101 is coupled with the master BMS 102 to communicate the battery estimations, such as SOC, SOH, over-charge, over-discharge, temperature of battery cells. The present traction battery pack 100 includes a master BMS 102 weld detection system using the controller 102a. The controller 102a is coupled with a voltage measuring circuit (not shown in figures) and a switching circuit 110 for measuring voltage across different terminals switched by the switching circuit 110. The switch circuit 110 switches the terminal for measuring voltage based on the inputs received from the controller 102a of the master BMS 102.
[0069] The switching circuit 110 switches between terminal ‘B’ and terminal ‘C’. The terminal ‘A’ is provided in between a positive contactor 103 and a fuse 107 provided on positive line (HV+) that connects positive terminal or electrode of the battery string 100a with positive terminal (HV+) of an inverter 108 or load 109, such as heater. The terminal ‘B’ is provided in between a negative contactor 104 and a negative terminal (HV-) of the battery string 110a on negative line (HV-) that connects negative terminal or electrode of the battery string 100a with negative terminal (HV-) of the inverter 108 or load 109, such as heater. Based on inputs received from the controller 102a, the switching circuit 110 connects the terminal ‘A’ with a terminal ‘C’. The terminal ‘C’ is provided in between the negative contactor 104 and negative terminal (HV-) of the inverter 108 or load 109. Switching instructions are pre-stored in memory of the controller 102a based on predefined sequence. The voltage measuring circuit coupled with the switching circuit to measure voltage ‘V1AB’, voltage ‘V2AC’, and voltage ‘Vinv’ of the inverter 108. In another embodiment, the voltage ‘Vinv’ may be voltage across terminal ‘C’ and terminal ‘Vinv’ where terminal ‘Vinv’ is provided in between the fuse 107 and the positive terminal (HV+) of the inverter 108.
[0070] The switching circuit 110 is shown as separate part in the figure, it can be separate part of integrated with the master BMS 102. In the present embodiment, it is integrated with the master BMS 102 and coupled with the controller 102a to receive switching instructions to switch the terminal connection for measurement of the voltage.
[0071] As show in the fig. 1, the pre-charge 105 is provided in parallel with the positive contactor 103 and a resistor 106 is provided in series with the pre-charge 105. A capacitor is provided across the positive and negative terminal of the inverter 108 to provide smoothness. Further, a load 109, such as heater that operates on high voltage is connected with the positive terminal (HV+) and the negative terminal (HV-) of the positive line and the negative line, respectively coming from the positive contactor 103 and the negative contactor 104.
[0072] The controller 102a of the master BMS 102 provides instructions to close and open the contactors where open and close means close state and open state of the contactors. The contactors are switches that may be relay operated switches to connect two terminal of a line. These contactors are operated by the controller 102a of the master BMS 102 for opening and closing.
[0073] The controller 102a is coupled with the inverter 108 through VCAN H and VCAN L lines to measure voltage across the inverter 108.
[0074] Fig. 2 illustrates sequence of time period where contactors are open and close to detect weld and abnormality of any of the contactors provide on positive line and negative line of the traction battery pack 100. As shown in fig. 2, the time frame is divided into two parts before closing the contactors means before turning ON the electric vehicle and before opening the contactors means before turning OFF the electric vehicle.
[0075] In an embodiment, the present traction battery pack 100 with the master BMS 102 with the controller 102a implements to detect weld and abnormality condition of any of the contactors before turning ON the vehicle.
[0076] In operation at time t0 in fig. 2, the controller 102a provides switching instructions to switch between terminal ‘C’ and the terminal ‘B’ by the switching circuit 110 to measure voltage ‘V1AB’ between the terminal ‘B’ and the terminal ‘A’ using the voltage measuring circuit. The controller 102a compare the voltage ‘V1AB’ with a threshold voltage value ‘Vth’ where the threshold voltage is low voltage, for example, 60V. The controller 102a determines that the positive contactor 103 or the pre-charge contactor 105 is welded when the voltage ‘V1AB’ is not less than or equal to the threshold voltage value ‘Vth’. The controller 102a closes the pre-charge contactor 105 and measures the voltage ‘V1AB’ after a first time ‘t1’ where t1=RC, R is resistance of resistor R and C is capacitance value of capacitor in the inverter 108. The controller 102a determines that pre-charge contactor 105 is normal when the voltage ‘V1AB’ is greater than or equal to the threshold voltage value ‘Vth’.
[0077] At time ‘t2’ where pre-charge contactor 105 is closed and other contactors are open, the controller 102a measures the voltage ‘V2AC’ after a first time ‘t2’. The controller 102a determines that the negative contactor 104 is welded when the voltage ‘V2AC’ is greater than or equal to the threshold voltage value ‘Vth’.
[0078] At time t3 where the pre-charge contactor 105 and the negative contactor 104 are closed, the controller 102 measure voltage ‘V2AC’ after time ‘t3’ and determines that the negative contactor 104 is abnormal when the voltage ‘V2AC’ is less than the threshold voltage value ‘Vth’.
[0079] At time ‘t4’ where the positive contactor 103 and the negative contactor 104 is closed and the pre-charge contactor 105 is opened, the controller 102a measures the voltage ‘V2AC’ and the voltage ‘Vinv’ which may be across terminal A and terminal Vinv. The controller determines that the positive contactor 103 is abnormal when the voltage ‘V2AC’ is less than a threshold voltage value ‘Vth1’ of the battery string 100a of the traction battery pack.
[0080] The controller 102a determines that the fuse 107 is blown when voltage ‘V2AC’ is not equal to the voltage ‘Vinv’.
[0081] When the controller 102a determined that either the positive contactor 103 or the pre-charge contactor 105 is welded, the controller 102a closes the negative contactor 104 and measures the voltage ‘V1AB’ and the voltage ‘V2AC’. When the voltage ‘V1AB’ is equal to the voltage ‘V2AC’, the controller 102a determines that negative contactor 104 is normal. The controller 102a further compares the voltage ‘V2AC’ with the voltage ‘Vinv’ and determines that the fuse 107 is blown when the voltage ‘V2AC’ is not equal to the voltage ‘Vinv’.
[0082] After time t6=2RC, the controller 102a turn ON the load 109 and measure the voltage ‘V1AB’. The controller 102a compares voltage ‘V1AB’ with the threshold voltage value ‘Vth1’ with the voltage of the battery string 100a and determines that the pre-charge contactor 105 is welded when the voltage ‘V1AB’ is less than a threshold voltage ‘Vth1’ of the battery string 100a. The controller 102a determines that the positive contactor 103 is welded when the voltage ‘V1AB’ is greater than the threshold voltage ‘Vth1’ of the battery string 100a.
[0083] As shown in fig. 2, the controller 102a detects weld and abnormality conditions of the contactors during turning OFF or opening of the contactor of the electric vehicle.
[0084] At time t4 where the positive contactor 103 and the negative contactor 104 is closed and the pre-charge contactor 105 is opened, the controller 102a measures the voltage ‘V2AC’, the voltage ‘V1AB’, and the voltage ‘Vinv’. The controller 102a determines that the fuse 107 is normal when the voltage ‘V2AC’, the voltage ‘V1AB’, and the voltage ‘Vinv’ are equal to each other.
[0085] After fifth time t5, where the negative contactor 104 is closed, and the positive contactor 103 and the pre-charge contactor 105 is opened, the controller 102a measures the voltage ‘V1AB’. The controller 102a compares the voltage ‘V1AB’ with the threshold voltage value ‘Vth’ and determines that pre-charge or positive contactor is welded when the voltage ‘V1AB’ is greater than or equal to the threshold voltage value ‘Vth’. The controller 102a determines that the pre-charge and positive contactors are not welded and normal when the voltage ‘V1AB’ is less than the threshold voltage value ‘Vth’.
[0086] The controller 102a turns ON the load 109 and measures the voltage ‘V1AB’ after sixth time ‘t6’ where t6=2RC. The controller 102a determines that the pre-charge contactor 105 is welded when the voltage ‘V1AB’ is less than the threshold voltage value ‘Vth1 of the battery string 100a. The controller 102a determines that the positive contactor 103 is welded when the voltage ‘V1AB’ is greater than the threshold voltage Vth1 of the battery string 100a.
[0087] At time t7, where all contactors are opened, the controller 102a measures the voltage ‘V1AB’ and the voltage ‘V2AC’ and determines that the negative contactor 104 is welded when the voltage ‘V1AB’ is equal to the voltage V2AC.
[0088] The controller 102 determines that the negative contactor 104 is abnormal when the voltage ‘V1AB’ is not equal to the voltage ‘V2AC’; and opens the positive contactor 103 and the negative contactor 104.
[0089] The controller 102a determines that fuse 107 is blown when the voltage ‘V2AC’ is not equal to the voltage ‘Vinv’.
[0090] It turns OFF all the passive protection devices (e.g. contactors), PEM and auxiliary to prohibit the vehicle from starting. Fig. 3 illustrates a method 200 for detecting weld and abnormality condition of contactors in the traction battery pack before turning ON the electric vehicle or during contactor closing. The method comprising:
[0091] At step 201, the method 200 includes checking all safety measures such as airbag deployment, short circuits, battery condition etc. If all safety checks are fine, the method proceeds to detect weld and abnormality condition of the contactors.
[0092] At step 202, the method 200 includes measuring a voltage ‘V1AB’ across terminal (A) and terminal (B) by a voltage measuring circuit.
[0093] At step 203, the method 200 includes comparing the voltage ‘V1AB’ with a threshold voltage value ‘Vth’.
[0094] At step 226, the method includes determining that the positive contactor 103 or the pre-charge contactor 105 is welded when the voltage ‘V1AB’ is greater than the threshold voltage value ‘Vth’.
[0095] At step 204, the method includes determining that the positive contactor 103 or the pre-charge contactor 105 is not welded when the voltage ‘V1AB’ is less than or equal to the threshold voltage value ‘Vth’.
[0096] At step 205, the method includes closing the pre-charge contactor 105 and measuring the voltage ‘V1AB’ after a first time t1=RC.
[0097] At step 206, the method includes comparing the voltage ‘V1AB’ with the threshold voltage value ‘Vth’.
[0098] At step 207, the method includes determining that the pre-charge contactor 105 is abnormal when the voltage ‘V1AB’ is not equal to or not greater than with the threshold voltage value ‘Vth’.
[0099] At step 208, the method includes determining that the pre-charge contactor 105 is normal when the voltage ‘V1AB’ is greater than or equal to the threshold voltage value ‘Vth’.
[00100] At step 209, the method includes measuring voltage ‘V2AC’ after time second ‘t2’.
[00101] At step 210, the method includes comparing the voltage ‘V2AC’ with the threshold voltage value ‘Vth’.
[00102] At step 211, the method includes determining that the negative contactor 104 is welded when the voltage ‘V2AC’ is greater than or equal to the threshold voltage value ‘Vth’.
[00103] At step 212, the method includes determining that the negative contactor 104 is not welded when the voltage ‘V2AC’ is less the threshold voltage value ‘Vth’.
[00104] At step 213, the method includes closing the negative contactor 104 and measuring the voltage ‘V2AC’ after third time ‘t3’.
[00105] At step 214, the method includes compare the voltage the voltage ‘V2AC’ with the threshold voltage value ‘Vth’. The threshold voltage value ‘Vth’ is pre-stored in the memory of the master BM 102.
[00106] At step 215, the method includes determining that the negative contactor 104 is abnormal when the voltage ‘V2AC’ is less than the threshold voltage value (Vth).
[00107] At step 216, the method includes determining that the negative contactor 104 is normal when the voltage ‘V2AC’ is greater than or equal to the threshold voltage value (Vth).
[00108] At step 217, the method includes closing the positive contactor 103 and opening the pre-charge contactor 105 and measuring the voltage (V2AC) and voltage of inverter (Vinv) after a fourth time ‘t4’.
[00109] At step 218, the method includes comparing the voltage (V2AC) with the threshold voltage value (Vth1) of the battery string 100a. The threshold voltage value (Vth1) of the battery string 100a is pre-stored in the memory of the master BMS 102.
[00110] At step 219, the method includes determining that positive contactor 104 is abnormal when the voltage (V2AC) is less than or equal to the threshold voltage value (Vth1) of the traction battery pack 100.
[00111] At step 220, the method includes determining that positive contactor 104 is normal when the voltage (V2AC) is greater to the threshold voltage value (Vth1) of the traction battery pack 100.
[00112] At step 221, the method includes comparing the voltage (V2AC) with the voltage of inverter (Vinv).
[00113] At step 223, the method includes determining that a fuse 107 is normal when the voltage (V2AC) is equal to the voltage of inverter (Vinv).
[00114] At step 222, the method includes determining that a fuse 107 is blown when the voltage (V2AC) is not equal to the voltage of inverter (Vinv).
[00115] At step 224, the method includes closing the contactors to turn ON the electric vehicle.
[00116] At step 225, the method includes opening all contactors when any of the contactor is abnormal or welded or the fuse is blown.
[00117] At step 226, once it is detected that either pre-charge contactor 105 or the positive contactor 103 is welded.
[00118] At step 227, the method includes closing the negative contactor 104 and measuring the voltage ‘V1AB’, a voltage (V2AC) across terminal (A) and terminal (C), and a voltage (Vinv) of an inverter 108.
[00119] At step 228, the method includes comparing the voltage ‘V1AB’ with the voltage (V2AC).
[00120] At step 229, the method includes determining that negative contactor 104 is normal when the voltage ‘V1AB’ is equal to the voltage (V2AC).
[00121] At step 235, the method includes determining that negative contactor 104 is abnormal when the voltage ‘V1AB’ is not equal to the voltage (V2AC).
[00122] At step 230, the method includes comparing the voltage (V2AC) with the voltage (Vinv).
[00123] At step 236, the method includes determining that fuse 107 is blown when the voltage (V2AC) is not equal to the voltage (Vinv).
[00124] At step 231, the method includes turning ON a load 109 and measuring the voltage (V1AB) after sixth time (t6=2RC).
[00125] At step 232, the method includes comparing the voltage (V1AB) with the threshold voltage value (Vth1) of the battery string 100a.
[00126] At step 233, the method includes determining that the positive contactor 106 is welded when the voltage (V1AB) is greater than the threshold voltage (Vth1) of the battery string 100a.
[00127] At step 234, the method includes determining that pre-charge contactor 105 is welded when voltage (V1AB) is less than a threshold voltage (Vth1) of a battery string 100a of the traction battery pack 100.
[00128] Fig. 4 illustrates a method 300 for detecting weld and abnormality condition of contactors in the traction battery pack before turning OFF the electric vehicle or during contactor closing. The method comprising:
[00129] At step 301, the method includes measuring a voltage (V1AB) across terminal (A) and terminal (B), a voltage (V2AC) across terminal (A) and terminal (C), a voltage (Vinv) of an inverter 108 by a voltage measuring circuit provided in a master Battery Management System (BMS) 102 and comparing the same with each other.
[00130] At step 302, the method includes determining that the fuse 107 is normal when the voltage (V1AB), the voltage (V2AC), and the voltage (Vinv) are equal to each other.
[00131] At step 303, the method includes opening the positive contactor 103 and measuring the voltage (V1AB) after a fifth time (t5).
[00132] At step 304, the method includes comparing the voltage (V1AB) with the threshold voltage (Vth).
[00133] At step 305, the method includes determining that the pre-charge contactor 105 or the positive contactor 103 is not welded and normal when the voltage (V1AB) is less than the threshold voltage value (Vth).
[00134] At step 306, the method includes determining that the pre-charge contactor 105 or the positive contactor 103 is welded when the voltage (V1AB) is greater than or equal to the threshold voltage value (Vth).
[00135] At step 307, the method includes turning ON the load 109 and measuring the voltage (V1AB) after time (t6=2RC).
[00136] At step 308, the method includes comparing the voltage (V1AB) with the threshold voltage value (Vth1) of the battery string 100a.
[00137] At step 309, the method includes determining that the pre-charge contactor 105 is welded when the voltage (V1AB) is less than a threshold voltage (Vth1) of the battery string 100a of the traction battery pack 100.
[00138] At step 310, the method includes determining that the positive contactor 103 is welded when the voltage (V1AB) is greater than the threshold voltage (Vth1) of the battery string 100a.
[00139] At step 311, the method includes opening the negative contactor 104 and measuring the voltage (V1AB) and the voltage (V2AC).
[00140] At step 312, the method includes comparing the voltage (V1AB) with voltage (V2AC).
[00141] At step 314, the method includes determining that the negative contactor 104 is welded when the voltage (V1AB) is equal to the voltage (V2AC).
[00142] At step 313, the method includes determining that the negative contactor 104 is not welded when the voltage (V1AB) is equal not to the voltage (V2AC).
[00143] At step 315, the method includes comparing the voltage (V1AB) is equal not to the voltage (V2AC).
[00144] At step 316, the method includes determining that the negative contactor 104 is abnormal when the voltage (V1AB) is not equal to the voltage (V2AC).
[00145] At step 317, the method includes determining that the negative contactor 104 is normal when the voltage (V1AB) is equal to the voltage (V2AC).
[00146] At step 318, the method includes comparing the voltage (V1AB), the voltage (V2AC) and the voltage (Vinv).
[00147] At step 319, the method includes determining that the fuse 107 is blown when the voltage (V2AC) is not equal to the voltage (Vinv).
[00148] At step 320, the method includes opening the positive contactor 103.
[00149] At step 321, the method includes opening the negative contactor 104.
[00150] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances, where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”
[00151] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

We claim:

1.A traction battery pack (100) of an electric vehicle, comprising:
a battery string (100a) coupled with a plurality of slave BMS (101) to supply high voltage (HV);
a master battery management system (BMS) (102) coupled with the plurality of slave BMS (101), the master BMS (102) having a controller (102a) coupled with a voltage measuring circuit and a switching circuit (110) to detect weld condition of a positive contactor (103), a negative contactor (104), and a pre-charge contactor (105) of the battery string (100a) before turning ON the electric vehicle;
characterized in that
the voltage measuring circuit coupled with the switching circuit to measure voltage (V1AB) between terminal (B) and terminal (A), voltage (V2AC) between terminal (A) and terminal (C), and voltage (Vinv) at an inverter (108);
the controller (102a) determines that the positive contactor (103) or the pre-charge contactor (105) is welded when the voltage (V1AB) is more than or equal to a threshold voltage value (Vth); and
the controller (102a) closes the pre-charge contactor (105) and measures the voltage (V2AC) to determine that the negative contactor (104) is welded when the voltage (V2AC) is greater than or equal to the threshold voltage value (Vth).

2. The traction battery pack (100) as claimed in claim 1, wherein the controller (102a):
closes the negative contactor (104) and measures the voltage (V1AB), the voltage (V2AC), and the voltage (Vinv);
determines that a fuse (107) is blown when the voltage (V2AC) is not equal to the voltage (Vinv).
3. The traction battery pack (100) as claimed in claim 2, wherein the controller (102a):
turns ON the load (109) and measures the voltage (V1AB);
determines that the pre-charge contactor (105) is welded when the voltage (V1AB) is less than a threshold voltage (Vth1) of the battery string (100a); and
determines that the positive contactor (103) is welded when the voltage (V1AB) is greater than the threshold voltage (Vth1) of the battery string (100a).

4. The traction battery pack (100) as claimed in claim 2, wherein the controller (102a):
closes the negative contactor (104) and measures the voltage (V1AB) and the voltage (V2AC);
determines that the negative contactor (104) is abnormal when the voltage (V1AB) is not equal to the voltage (V2AC).

5. The traction battery pack (100) as claimed in claim 1, wherein the controller (102a):
closes the pre-charge contactor (105) and measures the voltage (V1AB) to determine that the pre-charge contactor (105) is normal when the voltage (V1Ab) is greater than or equal to the threshold voltage value (Vth);
closes the negative contactor (104) and measures the voltage (V2AC) to determine that negative contactor (104) is normal when the voltage (V2AC) is greater than or equal to the threshold voltage value (Vth); and
closes the positive contactor (103) and opens the pre-charge contactor (105) and measures the voltage (V2AC) and voltage of inverter (Vinv) to:
determine that positive contactor (104) is normal when the voltage (V2AC) is greater to the threshold voltage value (Vth1) of the traction battery pack (100); and
determine that a fuse (107) is normal when the voltage (V2AC) is equal to the voltage of inverter (Vinv).

6. The traction battery pack (100) as claimed in claims 1-5, wherein the controller (102a) prohibits turning ON of the vehicle when any of the contactor is welded or abnormal.
7. A traction battery pack (100) of an electric vehicle, comprising:
a battery string (100a) coupled with a plurality of slave BMS (101) to supply high voltage (HV);
a master battery management system (BMS) (102) coupled with the plurality of slave BMS (101), the master BMS (102) having a controller (102a) coupled with a voltage measuring circuit and a switching circuit (110) to detect weld condition of a positive contactor (103), a negative contactor (104), and a pre-charge contactor (105) of the battery string (100a) before turning OFF the electric vehicle;
characterized in that
the voltage measuring circuit coupled with the switching circuit to measure voltage (V1AB) between terminal (B) and terminal (A), voltage (V2AC) between terminal (A) and terminal (C), and voltage (Vinv) at an inverter (108) or load (109);
the controller (102a) determines that a fuse (107) is blown when the voltage (V1AB) is equal to the voltage (V2AC) and the voltage (V2AC) is not equal to voltage (Vinv) of the inverter (108);
the contactor (102a) opens the positive contactor (103) and measures the voltage (V1AB) to determine that the pre-charge contactor (105) or the positive contactor (103) is welded when the voltage (V1AB) is greater or equal to a threshold voltage value (Vth).

8. The traction battery pack (100) as claimed in claim 7, wherein the controller (102a):
turns On the load (109) and measures the voltage (V1AB);
determines that the pre-charge contactor (105) is welded when the voltage (V1AB) is less than a threshold voltage (Vth1) of the battery string (100a); and
determines that the positive contactor (103) is welded when the voltage (V1AB) is greater than the threshold voltage (Vth1) of the battery string (100a).

9. The traction battery pack (100) as claimed in claim 8, wherein the controller (102a):
opens the negative contactor (104) and measures the voltage (V1AB) and the voltage (V2AC);
determines that the negative contactor (104) is welded when the voltage (V1AB) is equal to the voltage (V2AC).

10. The traction battery pack (100) as claimed in claim 7, wherein the controller (102a):
determines that the negative contactor (104) is abnormal when the voltage (V1AB) is not equal to the voltage (V2AC); and
opens the positive contactor (103) and the negative contactor (104).

11. The traction battery pack (100) as claimed in claim 7, wherein the controller (102a):
opens the positive contactor (103) and measures the voltage (V1AB) to determine that the pre-charge contactor (105) and the positive contactor (103) is normal when the voltage (V1AB) is less than the threshold voltage value (Vth).

12. A method (200) for detecting weld condition of a positive contactor (103), a negative contactor (104), a pre-charge contactor (105) and blown condition of a fuse (107) of a traction battery pack during turning ON of an electric vehicle, the method (200) comprising:
measuring (202) a voltage (V1AB) by a voltage measuring circuit;
comparing (203) the voltage (V1AB) with a threshold voltage value (Vth);
determining (226) that the positive contactor (103) or the pre-charge contactor (105) is welded when the voltage (V1AB) is greater than the threshold voltage value (Vth);
closing (227) the negative contactor (104) and measuring the voltage (V1AB), a voltage (V2AC), and a voltage (Vinv) of an inverter (108);
turning ON (231) a load (109) and measuring the voltage (V1AB);
determining (234) that pre-charge contactor (105) is welded when voltage (V1AB) is less than a threshold voltage (Vth1) of a battery string (100a) of the traction battery pack (100); and
determining (233) that the positive contactor (106) is welded when the voltage (V1AB) is greater than the threshold voltage (Vth1) of the battery string (100a);
13. The method (200) as claimed in claim 12, wherein the method (200) comprises:
closing (205) the pre-charge contactor (105) and measures the voltage (V2AC);
determining (211) that the negative contactor (104) is welded when the voltage (V2AC) is greater than or equal to the threshold voltage value (Vth).

14. The method (200) as claimed in claim 7, wherein the method (200) comprises:
closing (213) the negative contactor (104) and measures the voltage (V2AC);
determining (216) that the negative contactor (104) is normal when the voltage (V2AC) is greater than or equal to the threshold voltage value (Vth).

15. The method (200) as claimed in claim 13, wherein the method (200) comprises:
closing (216) the positive contactor (103) and opening the pre-charge contactor (105) and measuring the voltage (V2AC) and voltage of inverter (Vinv);
determining (220) that positive contactor (104) is normal when the voltage (V2AC) is greater than the threshold voltage value (Vth1) of the traction battery pack (100); and
determining (223) that a fuse (107) is normal when the voltage (V2AC) is equal to the voltage of inverter (Vinv).
16. A method (300) for detecting weld condition of a positive contactor (103), a negative contactor (104), a pre-charge contactor (105), and blown condition of a fuse (107) of a traction battery pack during turning OFF of an electric vehicle, the method (300) comprising:
measuring (301) a voltage (V1AB), a voltage (V2AC), a voltage (Vinv) of an inverter (108) by a voltage measuring circuit provided in a master Battery Management System (BMS) (102);
opening (303) the positive contactor (103) and measuring the voltage (V1AB); and
determining (306) that the pre-charge contactor (105) or the positive contactor (103) is welded when the voltage (V1AB) is greater than or equal to a threshold voltage value (Vth).

17. The method (300) as claimed in claim 16, wherein the method (300) comprises:
turning (307) ON the load (109) and measuring the voltage (V1AB);
determining (309) that the pre-charge contactor (105) is welded when the voltage (V1AB) is less than a threshold voltage (Vth1) of a battery string (100a) of the traction battery pack (100); and
determining that the positive contactor (103) is welded when the voltage (V1AB) is greater than the threshold voltage (Vth1) of the battery string (100a).

18. The method (300) as claimed in claim 17, wherein the method (300) comprises:
opening (311) the negative contactor (104) and measuring the voltage (V1AB) and the voltage (V2AC); and
determining (314) that the negative contactor (104) is welded when the voltage (V1AB) is equal to the voltage (V2AC).

19. The method (300) as claimed in claim 18, wherein the method (300) comprises:
determining (316) that the negative contactor (104) is abnormal when the voltage (V1AB) is not equal to the voltage (V2AC); and
opening (320, 321) the positive contactor (103) and the negative contactor (104).

20. The method (300) as claimed in claim 16, wherein the method (300) comprises:
opening (303) the positive contactor (103) and measuring the voltage (V1AB); and
determining (305) that the pre-charge contactor (105) and the positive contactor (103) is normal when the voltage (V1AB) is less than the threshold voltage value (Vth).
21. The method (300) as claimed in claim 16, wherein the method (300) comprises:
determining (319) that the fuse (307) is blown when the voltage (V2AC) is not equal to the voltage (Vinv) of the inverter (108).