Patent Publication Number: US-2022219544-A1

Title: Method of operating battery management systems, corresponding device and vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/893,771, filed on Jun. 5, 2020, which claims priority to Italian Patent Application No. 102019000009237, filed on Jun. 17, 2019, and is related to U.S. patent application Ser. No. 16/420,875, filed on May 23, 2019 and claiming priority to IT 102018000005810 (filed May 29, 2018); U.S. patent application Ser. No. 16/420,992, filed on May 23, 2019 and claiming priority to IT 102018000005828 (filed May 29, 2018); and U.S. patent application Ser. No. 16/893,729 filed on Jun. 5, 2020 and claiming priority to IT 102019000009234 (filed Jun. 17, 2019), all of which applications are hereby incorporated herein by reference as if reproduced in their entireties. 
    
    
     TECHNICAL FIELD 
     The description relates to battery management systems as well as a corresponding device and vehicle. 
     BACKGROUND 
     The evolving technology of electric vehicles (EVs) and hybrid electric vehicles (HEVs) makes improved performance of battery management systems (BMS) a desirable feature in order to facilitate safe, reliable and cost-efficient battery operation. 
     A task of a battery management system (BMS) involves measuring the battery cells&#39; voltage. This in turn involves extracting relatively small voltages from comparatively high common mode voltages. 
     Additionally, it is noted that, for instance in automotive applications, the electric motor of the vehicle and its associated driver circuitry may be the source of noise in the form of currents injected into the battery cells or as a voltage drops across these cells. These may represent a source of electromagnetic interference over a wide range of frequencies with possible undesired effects on functional measurements. 
     Lack of accuracy in these measurements may adversely affect battery pack longevity and performance. 
     Accuracy may be pursued by placing differential voltage amplifiers with a high common-mode rejection ratio (CMRR) at each cell to provide a voltage level shift (that is translated signals) available to be digitized by an analogue-to-digital converter (ADC). Such a stage can be equipped with a number of other features such as protection and diagnostics (open load detection, leakage detection, built-in self-test or BIST, for instance). Such features are highly desirable in the automotive sector in order to facilitate complying with safety specifications. 
     A desirable feature of arrangements as considered herein is that, as a result of a faulty condition being detected via a built-in self-test, for instance the possibility may exist of maintaining detection of undervoltage (UV) and/or overvoltage (OV) conditions occurring in the cells in a battery pack. 
     SUMMARY 
     The description relates to battery management systems. One or more embodiments can be applied in the automotive field, for instance to electric vehicles and/or hybrid electric vehicles 
     One or more embodiments can contribute in providing improved solutions along the lines discussed in the foregoing. 
     One or more embodiments may relate to a corresponding device, for instance a battery management system or BMS. 
     One or more embodiments may relate to a vehicle (for instance, a motor vehicle such as an EV or a HEV) equipped with such a device. 
     The claims are an integral part of the technical description of one or more embodiments as provided herein. 
     One or more embodiments may provide a secondary or auxiliary path, independent of a main one, to detect UV/OV conditions of cells. 
     One or more embodiments may thus provide a certain redundancy to diagnose errors/faults while retaining the capability of operating adequately, even if at a reduced performance level. 
     One or more embodiments may facilitate achieving that result saving semiconductor area. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       One or more embodiments will now be described, by way of example only, with reference to the annexed figures, wherein: 
         FIG. 1  is a block diagram exemplary of a possible context of use of embodiments, 
         FIG. 2  is a block diagram exemplary of a device to which embodiments may apply, 
         FIG. 3  is a circuit diagram exemplary of a portion of the device of  FIG. 2 , 
         FIG. 4  is a diagram exemplary of a possible structure of embodiments, 
         FIGS. 5 and 6  are diagrams exemplary of operation of embodiments, and 
         FIG. 7  is a flow chart exemplary of possible operation in embodiments. 
     
    
    
     DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     In the ensuing description, one or more specific details are illustrated, aimed at providing an in-depth understanding of examples of embodiments of this description. The embodiments may be obtained without one or more of the specific details, or with other methods, components, materials, etc. In other cases, known structures, materials, or operations are not illustrated or described in detail so that certain aspects of embodiments will not be obscured. 
     Reference to “an embodiment” or “one embodiment” in the framework of the present description is intended to indicate that a particular configuration, structure, or characteristic described in relation to the embodiment is comprised in at least one embodiment. Hence, phrases such as “in an embodiment” or “in one embodiment” that may be present in one or more points of the present description do not necessarily refer to one and the same embodiment. Moreover, particular conformations, structures, or characteristics may be combined in any adequate way in one or more embodiments. 
     The references used herein are provided merely for convenience and hence do not define the extent of protection or the scope of the embodiments. 
     As discussed, a desirable feature of arrangements as considered herein is that, as a result of a faulty condition being detected, via a built-in self-test procedure, for instance, the possibility may exist of maintaining detection of undervoltage (UV) and/or overvoltage (OV) conditions occurring in the cells in a battery pack. 
     Various solutions have been devised as discussed previously which are capable of performing a fault diagnosis, with a built-in self-test (BIST) procedure run and an error flag activated if an error is found to occur. 
     Examples of such an error/fault/failure (these designations are used herein as synonyms) may be represented by a lack of integrity of level shifters embedded in an analog front end and/or by an analog-to-digital converter or ADC being out of compliance due to bandgap deviation or other errors. 
     Arrangements for performing such acts may comprise various arrangements known to those of skill in the art. 
     Arrangements for performing such acts may also comprise various arrangements discussed in Italian patent applications 102018000005810 (U.S. counter-part publication 2019/0366849), 102018000005828 (U.S. counter-part publication US20190372178), and 102019000009234 (filed on the same date the priority application of the present case). Each of these applications is incorporated herein by reference. 
     As a result of such a flag being activated one may conceive to enable a set of window comparators and/or to add a secondary processing chain (an analog-to-digital converter or ADC, for instance). 
     Such solutions may be hardly acceptable in order to comply with safety specifications (in the automotive area, for instance) insofar as vehicle stopping may ensue. 
     Also, adding a set of programmable UV/OV (undervoltage/overvoltage) comparators for the cells able to operate even in the presence of a fault on the main detection path involves an intrinsic redundancy likely to have a negative impact on circuit complexity and semiconductor area. For instance, in the presence of n cells, 2 n  comparators would be involved in detecting UV/OV conditions. 
     Adding a secondary processing chain (an analog-to-digital converter or ADC, for instance) may look more promising as a solution insofar as that approach may facilitate obtaining the actual voltage of a cell, in addition to merely detecting an UV/OV condition. Also, a secondary measurement path via, for instance, a single 10-bit successive approximation register (SAR) ADC with an input multiplexer may facilitate performing additional tasks such as measuring external resistors, analog signals on GPIO pins, and various internal voltages. 
     This solution would be again likely to have a negative impact on circuit complexity and semiconductor area. Such a negative impact could be attempted to be palliated by using a single (possibly simplified) ADC multiplexed over the various cells, which in turn would have undesired effects in terms of reduced performance and measurements on individual cells being staggered over time. 
       FIG. 1  is exemplary of a possible arrangement of a battery pack BP equipping a vehicle V such as an electric vehicle (EV) or a hybrid electric vehicle (HEV) with an associated battery management system BMS. A lithium battery pack may be exemplary of such a battery pack. 
     Reference to such a possible area of application and/or to such battery technology is not however to be understood in a limiting sense of embodiments. 
     In one or more embodiments as exemplified herein, the battery management system BMS may comprise a device  10  (for instance an integrated circuit IC) providing various features desirable in performing battery management, for instance with a (single) device  10  configured to monitor from 4 up to 14 cells C. 
     In one or more embodiments, the device  10  can be configured to co-operate with a power supply PS (which may be derived from the very battery pack BP monitored by the device  10 ), a communication interface CI and logic circuitry L. 
     In one or more embodiments the logic block L exemplified in  FIG. 1  may comprise such a microcontroller. 
     The device  10  may also generate stable internal references, for instance by means of a voltage regulator and bootstrap circuit. Also, it may comprise bandgaps as monitored by internal circuitry to facilitate measurement accuracy. 
     A task of the device  10  may comprise monitoring cell and battery pack status through stack voltage measurement and cell voltage measurement. The related measurement and diagnostic tasks can be executed either on demand or periodically, for instance with a programmable cycle interval. 
     Measurement data may be made available for an external controller to perform a charge balancing and to compute data indicative of the State of Health (SOH) and State of Charge (SOC) of the cells/battery pack. 
     In a normal operating mode, the device  10  may perform measurement conversions, diagnostics and communication tasks. Optionally, the device  10  can be set to a cyclic wake up state, thus reducing current consumption (for instance as absorbed from the battery pack BP). While in the cyclic wake up state, the main functions of the device  10  are activated periodically. 
     The device available with the trade designation L9963 with companies of the STMicroelectronics group may be exemplary of a conventional arrangement for such a device  10 . 
     In one or more embodiments a device  10  as exemplified herein may comprise a set of converters CV 1 , . . . , CV 14  as well as balance circuit blocks B 1 , . . . , B 14  associated to respective cells C in the battery pack BP. 
     For instance, the circuit blocks B 1 , . . . , B 14  can provide (passive) cell balancing via internal discharge paths. This action aims at balancing cells in order to facilitate an equalized charge distribution over all the cells. This is found to improve performance of the battery pack BP. 
     A device  10  as exemplified herein can be configured to perform automatic “validation” of failure events involving the individual cells C, or the whole battery pack BP. 
     The related tests can be performed automatically, for instance in the case of a failure involving either a cell C or the battery pack BP. This facilitates providing reliable information (for instance via the communication interface, CI) to an external microcontroller supervising operation of the battery management system BMS. 
     Automatic “validation” of such failure events may take place in various ways, for instance as discussed in Italian patent applications 102018000005810, 102018000005828 and 102019000009234 already cited. 
     In fact, embodiments as exemplified herein are primarily directed to acts which may be performed as a result of a failure or error event detected rather than to techniques for detecting such failures or errors. 
     A device  10  as exemplified herein may thus comprise at least some of the features of a BIST circuit as disclosed in Italian patent applications 102018000005810, 102018000005828, and 102019000009234 already repeatedly cited. 
     The representation provided in  FIG. 1  is a general functional description of the device  10 . 
     More in detail, a device  10  as exemplified herein (see, for instance,  FIG. 2 ) may comprise charge-sensing pins Cn, namely C 0 , C 1 , . . . , C 14 , in the case exemplified herein. The charge-sensing pins Cn are coupled to the cells C in the battery pack BP, with, for instance, an n-th cell, Celln, arranged between the pins Cn and Cn−1. 
     As exemplified herein (see again, for instance,  FIG. 2 ) a first cell Cell 1  is shown arranged between the pins C 0  and C 1  and so on up to the cell Cell 14  arranged between the pins C 13  and C 14 . 
     For the sake of simplicity, the various cells can be considered as identical. Each of them may thus have a resistor R LPF , arranged coupling the pins C 0 , . . . , C 14 , to respective ends of the cells Cell 1 , . . . , Cell 14  and a capacitor CAP between adjacent pins. 
     The resistors R LPF  and the capacitors CAP provide respective low-pass RC filters, which facilitate filtering out unwanted signals at the battery terminals. 
     In one or more embodiments the pins C 0 , . . . , C 14  of the device  10  can be regarded as high-impedance nodes so that no appreciable voltage drop maybe assumed to occur across the resistors R LPF . 
     Consequently, a (differential) voltage V diff  substantially corresponding to the voltage across the n-th cell Celln maybe assumed to be available for “reading” between adjacent pins Cn−1 and Cn. 
     In one or more embodiments, further pins designated Sn (n=1, . . . , 14) as well as pins Bn_n−1 (with N=2, . . . , 14 in the case exemplified herein) may be used for balance purposes, namely for discharging cells which are detected to be “too charged” in order to equalize the distribution of charge over all the cells. 
     The amount of the (balance) discharge current may be set by resistors R DIS  coupling the “even numbered” S pins, namely S 2 , . . . , S 14  to the “upper” end (namely the end or node towards the overall voltage Vb of the battery pack), and the “odd numbered” S pins, namely S 1 , . . . , S 13  to the “lower” end or node (opposite the battery pack voltage VB, that is towards ground GND) of the corresponding cell. 
     The pins Bn_n−1 are (directly) coupled between the resistors R LPF  and the corresponding ends of the cells Cell 1 , . . . , Cell 14  where no discharge resistor R DIS  are provided. 
       FIG. 3  details by way of simplicity the arrangement discussed in the foregoing with reference to the two “uppermost” cells in the battery pack BP exemplified herein, namely Cell 14  and a Cell 13  by showing the corresponding coupling of the pins C 12 , C 13 , C 14 , S 13 , S 14 , and B 14 - 13  of the device  10 . The associated capacitors CAP shown in  FIG. 2  are not reproduced in  FIG. 3  for simplicity. 
     The device  10  as exemplified herein may thus be considered to comprise a plurality of charge-sensing pins C 0  to C 14  which can be regarded as arranged in an ordered (numbered) sequence of pins C 0  to C 14 , for instance starting from ground GND to the “upper” voltage Vb node or bar of the battery pack BP, with these charge-sensing pins comprising even-numbered pins (C 0 , C 2 , C 4 , . . . , C 14 ) interleaved with odd-numbered pins (C 1 , C 3 , . . . , C 13 ). 
     Also, the pins C 0  to C 14  can be seen as comprising a plurality of pairs of charge-sensing pins, namely C 0 , C 1 ; C 1 , C 2 ; . . . ; C 12 , C 13 ; C 13 , C 14  arranged in an ordered sequence of: 
     those pairs of charge-sensing pins that are in odd-numbered positions ( 1 ,  3 ,  5 ,  7 ,  9 ,  11 ,  13 ) in the ordered sequence (from ground GND to Vb) of charge-sensing pins C 1  to C 14  exemplified herein, namely: 
     C 0 , C 1 ; 
     C 2 , C 3 ; 
     C 4 , C 5 ; 
     C 6 , C 7 ; 
     C 8 , C 9 ; 
     C 10 , C 11 ; 
     C 12 , C 13 ; and 
     those pairs of charge-sensing pins that are in even-numbered positions ( 2 ,  4 ,  6 ,  8 ,  10 ,  12 ,  14 ) in the ordered sequence (from ground GND to Vb) of charge-sensing pins C 1  to C 14  exemplified herein, namely: 
     C 1 , C 2 ; 
     C 3 , C 4 ; 
     C 5 , C 6 ; 
     C 7 , C 8 ; 
     C 9 , C 10 ; 
     C 11 , C 12 ; 
     C 13 , C 14 . 
     The charge sensing pins in the pairs of charge-sensing pins in the plurality of pairs (C 0 , C 1 ; C 1 , C 2 ; . . . ; C 12 , C 13 ; C 13 , C 14 ) of charge-sensing pins are coupled via a coupling resistor (R LPF ) to a respective cell (Cell 1 , Cell 2 , . . . , Cell 13 , Cell 14 ) in the battery pack BP to sense the voltage across the respective cell. 
     Also, each odd-numbered (C 0 , C 1 ; . . . ; C 12 , C 13 ) resp. even-numbered (C 1 , C 2 ; . . . ; C 13 , C 14 ) pair of charge-sensing pins shares a common charge sensing pin (C 1 , . . . , C 13 ) with the subsequent even-numbered pair (C 1 , C 2 ; . . . ; C 13 , C 14 ) resp. previous odd-numbered pair (C 0 , C 1 ; . . . ; C 12 , C 13 ) of charge-sensing pins in the ordered sequence of odd- and even-numbered pairs of charge-sensing pins. 
     For instance, as seen in  FIG. 3 : 
     the odd-numbered pair C 12 , C 13  of charge-sensing pins shares a common charge sensing pin, namely C 13 , with the subsequent even-numbered pair C 13 , C 14  in the ordered sequence of charge sensing pins, and, likewise the even-numbered pair C 13 , C 14  of charge-sensing pins shares a common charge sensing pin, again C 13 , with the previous odd-numbered pair C 12 , C 13  in the ordered sequence of charge sensing pins. 
     Also, the charge distribution pins as exemplified herein can be regarded as comprising first charge distribution pins S 1 , . . . , S 14  and second charge distribution pins B 2 - 1 , . . . , B 14 - 13 . 
     By again referring to  FIG. 3 , one may further note that, in a device  10  as exemplified herein, each odd-numbered pair of charge-sensing pins (C 12 , C 13 , in the case of  FIG. 3 ) and the subsequent even-numbered pair (C 13 , C 14 , in the case of  FIG. 3 ) of charge-sensing pins in the ordered sequence of odd- and even-numbered pairs of charge-sensing pins comprise: 
     a) an odd-numbered first charge distribution pin (S 13 , in the case of  FIG. 3 ) coupled via a discharge resistor R DIS  to the charge sensing pin (C 12 , in the case of  FIG. 3 ) of the odd-numbered pair (C 12 , C 13 , in the case of  FIG. 3 ) of charge-sensing pins other than the common charge sensing pin (C 13 , in the case of  FIG. 3 ), 
     b) an even-numbered first charge distribution pin (S 14 , in the case of  FIG. 3 ) coupled via a discharge resistor R DIS  to the charge sensing pin (C 14 , in the case of  FIG. 3 ) of the even-numbered pair (C 13 , C 14 , in the case of  FIG. 3 ) of charge-sensing pins other than the common charge sensing pin (C 13 , in the case of  FIG. 3 ), 
     c) a second charge distribution pin (B 14 - 13 , in the case of  FIG. 3 ) coupled via a charge sensing resistor R LPF  to the common charge sensing pin (C 13 , in the case of  FIG. 3 ), the second charge distribution pin (here B 14 - 13 ) configured to be selectively coupled via switches SW 13 , SW 14  to the odd-numbered first charge distribution pin (S 13 , in the case of  FIG. 3 ) and the even-numbered first charge distribution pin (S 14 , in the case of  FIG. 3 ) to exchange electrical charge therewith in order to perform a charge balance function. 
     As represented for the sake of simplicity (only) in  FIG. 3 , when the balance function is activated on a specific cell, associated switch circuitry is activated to discharge the cell with a current whose intensity I is given by the ratio V Diff /R DIS . Two such switches (SW 13  or SW 14  in  FIG. 3 , which maybe implemented as electronic switches such as a MOSFET transistor) are shown in  FIG. 3  as associated with the cells Cell 13  and Cell 14 . A similar arrangement (not visible in the figures for simplicity) may apply to the other cells in the battery pack BP. 
     As discussed previously, R LPF  and CAP define the pole (that is, the cut-off or corner frequency) of the low-pass charge-sensing filter, while the resistance value of the resistors R DIS  defines the discharge cell current for balance purposes. 
     It will be appreciated that, while exemplified herein with reference to  FIG. 3 , where only the two cells Cell 13  and Cell 14  are visible, the arrangement discussed in the foregoing can be reproduced for all of the odd-numbered and even-numbered charge pin pairs in the device  10 . 
     As noted, the ability of providing (secondary) UV/OV detection possibly along with the ability of providing an accurate measurement of cell voltages (without impairment in term of accuracy) in the presence of a fault/error is a highly desirable feature, for instance in the automotive sector. 
     For that purpose, one or more embodiments may take advantage of the presence of charge sensing/distribution pins and the associated circuitry (ADCs, for instance) already provided for charge sensing/balance and fault/error detection in arrangement as discussed in the foregoing. 
     Detection of UV/OV conditions together with cell voltage measurement without impairment in term of accuracy can thus be facilitated in one or more embodiments by saving semiconductor area with adequate performance maintained. 
     In one or more embodiments, this type of operation can be implemented (for instance via software code loaded in the logic circuitry L) “swapping” cells and associated ADCs in such a way that cell voltages can (still) be acquired by adjacent signal sensing circuits (primarily ADCs) with moderate efforts in terms of logic circuitry and with virtually no penalty in terms of semiconductor area. 
     For instance, this may involve exploiting switching, multiplexer and ADC circuitry as exemplified in  FIG. 4 , which maybe compatible with an open load and cell measurement arrangement as disclosed in Italian patent application 102018000005828, already repeatedly cited. 
     A secondary UV/OV procedure can thus be run—on demand, for instance—when a fault (failure) or error is detected to occur, in an ADC, for instance) via any known technique (a built-is self-test or BIST, for instance). As a result of a corresponding conversion being held to be no longer valid (due to the fault, failure or error—as noted, these designations are used herein essentially as synonyms), that conversion is no longer taken into account and a swap function of cells is enabled, with a corresponding alternative UV/OV diagnostics (and cell voltage measurement) feature made available. 
     For the sake of simplicity,  FIG. 4  refers to only two cells of the plurality of cells C, namely Cell 11  (coupled between the odd-numbered pair of pins C 10  and C 11 ), and Cell 12  (coupled between the even-numbered pair of pins C 11  and C 12 ). 
     It will be otherwise understood that these two cells may be regarded as lying between a set of “lower” cells LC, namely Cell 1  to Cell 10  and a set of “higher” cells HC, namely Cell 13  and Cell 14 . 
     As exemplified in  FIG. 4  the “odd-numbered” cells (Cell 11  being exemplary of these) are shown coupled with a cascaded arrangement of a multiplexer  30 O ( 30 -Odd) and an analog-to-digital converter (ADC)  40 O ( 40 -Odd). 
     Similarly, the “even-numbered” cells (Cell 12  being exemplary of these) are shown coupled with a cascaded arrangement of a multiplexer  30 E ( 30 -Even) and an analog-to-digital converter (ADC)  40 E ( 40 -Even). 
     In one or more embodiments as exemplified in  FIG. 4  the converters  40 E and  40 O are supplied by respective reference voltages (bandgaps) V bg1 , V bg2  produced—in a manner known to those of skill in the art—to be (completely) independent from each other. Undesired variations in such bandgap voltages (suited to be detected in a manner known to those of skill in the art or with the solution described in the co-pending application of even date repeatedly cited in the foregoing) maybe regarded, among other events, as such possible fault or error. 
     For the sake of simplicity, only the multiplexer  30 O,  30 E and the analog-to-digital converter (ADC)  40 O,  40 E of the associated processing chains are visible in  FIG. 4 : other circuits such as a voltage level shifter block and a digital filter can be considered as incorporated to other blocks in  FIG. 4 . Just to make an example, a level shifter can be regarded as embedded in an analog front end of the ADC. 
     It will be otherwise appreciated that—while illustrated as individual, distinct elements for the sake of simplicity and ease of understanding—the various components  30 O,  40 O, and  30 E,  40 E may incorporated to single combined components. 
     In one or more embodiments, the multiplexers  30 O,  30 E may comprise each three input lines and two output lines, supplemented, in the case of the multiplexer  30 E by a further (fourth) input line (labeled SL=swap line) configured to be exploited in implementing a “cell swapping” act as discussed in the following. 
     In one or more embodiments, the multiplexers  30 O,  30 E can be configured to apply to the inputs of the corresponding ADCs  40 O,  40 E the (voltage) signals sensed across the respective cell. 
     For instance, the multiplexer  30 O may be configured to have applied to its input pins C 10 , C 11  the voltage sensed across the Cell 11  (via resistors R 10 , R 11 , exemplary of corresponding resistors R LPF —again, the associated capacitors CAP are not visible for simplicity), while the multiplexer  30 E may be configured to have applied to its input pins C 11 , C 12  the voltage sensed across the Cell 12  (via resistors R 11 , R 12  exemplary of corresponding resistors R LPF —once more, the associated capacitors CAP are not visible for simplicity). 
     As exemplified in  FIG. 4 , in one or more embodiments, the multiplexers  30 O (odd-numbered cells) and  30 E (even-numbered cells) may be coupled in such a way that, in each pair of an odd-numbered cell (here Cell 11 ) and an even-numbered cell (here Cell 12 ), the “odd-numbered” multiplexer  30 O is also coupled to the “S” pin of the even-numbered cell (here, pin S 12 ) while the “even-numbered” multiplexer  30 E is also coupled to the Bn_n−1 pin (here B 12 _ 11 ) coupled between the two cells in the pair (here Cell 11  and Cell 12 ). 
     As exemplified in  FIG. 4 , in one or more embodiments, the multiplexers  30 E (even-numbered cells) may also have its fourth input adapted to be coupled (via the swap line SL and the resistor R 10 , for instance) to the pin C 10 , namely the voltage sensing pin in the odd-numbered cell (here Cell 11 ) other than the pin (namely C 11 ) which is common to the odd-numbered cell (here Cell 11 ) and the even-numbered cell (here Cell 12 ). 
     The flowchart of  FIG. 7  is exemplary of possible operation of an arrangement as exemplified herein. 
     Block  100  after START in the flowchart of  FIG. 7  is exemplary of “normal” operation of the system (that is in the absence of faults detected) wherein the multiplexers  30 E,  30 O are controlled by the logic circuit L in such a way that: 
     the (voltage) signals at pins C 12  and C 11 , namely V C12  and V C11  are applied to the even-numbered ADC  40 E; 
     the (voltage) signals at pins C 11  and C 10 , namely V C11  and V C10 , are applied to the odd-numbered ADC  40 O. 
     Conversion, performed in manner known per se in the converters  40 E,  40 O (for instance sigma-delta ADC converters), will result in a first differential signal V 12 =V C12 −V C11  (that is the difference of the signals at C 12  and C 11 ) and a second differential signal V 11 =V C11 −V C10  (that is, the difference of the signals at C 11  and C 10 ) applied to the logic circuit L (in any known manner). 
     One or more embodiments may involve recognizing that, with the system operating correctly (no open load or leakage, for instance), with voltage drops across R 12  and R DIS  negligible, the voltages at C 12  and S 12  will be expectedly equal (that is with V C2 −V C1 =V S12 −V C1 ). 
     Block  200  in  FIG. 7  is exemplary of various signal processing which maybe performed with the capability of checking, as exemplified at  202 , whether a certain signal processing chain intended to convert a voltage signal across one of the cells (as exemplified by  30 O,  40 O and  30 E,  40 E in  FIG. 4 ) is operating adequately or is affected by a fault. 
     Such processing/check may involve any of a plurality of procedures (including Built-In Self-Test or BIST procedures) known to those of skill in the art for that purpose. 
     Such processing/check may involve a multi-step procedure involving a first “accurate” BIST act suited to detect more or less serious faults at a cell level, possibly followed, in the case a serious fault is detected, by a “rougher” test capable of identifying the part or element (an analog-to-digital converter or ADC, for instance) responsible for the fault. 
     For instance, the Italian patent application 102019000009234 exemplifies signal processing (in the logic circuit L—for instance) which involves calculating the absolute value (abs) of the difference between V C2 −V C1  and V S2 −V C11 —with that absolute value (modulus) compared with a given threshold, with the capability of detecting and distinguishing accurately more or less serious faults at cell level. 
     Also, Italian patent applications 102018000005810 (already repeatedly cited) discloses a BIST procedure for a differential ADC capable of identifying a faulty ADC as a result of a fault detected at a cell level. 
     For the sake of the explanation herein, one may assume that, irrespective of the specific implementation of the acts exemplified by blocks  200  and  202 : 
     a negative outcome (N) of the act of block  202  (exemplified as a certain “faultiness” threshold Vth not exceeded) will result in normal operation being continued; 
     a positive outcome (Y) of the act of block  202  (exemplified as a certain “faultiness” threshold Vth exceeded) will result in a faulty condition being declared in an act  204  for one of the signal processing chains (one of the ADCs  40 O or  40 E, for instance) associated with the cell pair comprising Cell 11  and Cell 12 . 
     As exemplified herein, the faulty condition declared in the act  204  (whatever this may be and however detected) may result in the conversion (originally) provided—for either one of the cells Cell 11  or Cell 12 , for instance for the Cell 12  via the multiplexer  30 E and the ADC  40 E—being disregarded (that is not being taken into account, by being possibly declared “not available”). 
     In one or more embodiments, this will lead to a “cell swap” act  206  wherein the multiplexers  30 E,  30 O are controlled (by the logic circuit L) in such a way that: 
     the (voltage) signals at pins C 11  and C 10 , which are both available at the input of the multiplexer  30 E (via the swap line SL, in the case of the voltage at C 10 ) are applied to the even-numbered ADC  40 E with the ADC  40 E configured to provide (in the place of the signal V 12 =V C12 −V C11  expected to be provided by  40 E in normal operating conditions and indicative of the voltage drop across the cell Cell 12 ) a “swapped” signal V 12 ′=V C11 −V C10  (see the downward pointing arrow shown in the block  40 E) indicative of the voltage drop across the cell Cell 11 , 
     the (voltage) signals at pins S 12  and C 11 , which are both available at the input of the multiplexer  30 O are applied to the odd-numbered ADC  40 O with the ADC  40 O configured to provide (in the place of the signal V 11 =V C11 −V C10  expected to be provided by  40 O in normal operating conditions and indicative of the voltage drop across the cell Cell 11 ) a “swapped” signal V 11 ′=V S12 −V C11  (see the downward pointing arrow shown in the block  40 O) indicative of the voltage drop across the cell Cell 12 . 
     In that way, assuming, for instance, that the ADC  40 E is faulty, so that the signal V 12 =V C12 −V C11  originally provided thereby is unreliable (“not available”), as a result of swapping, the corresponding measurement can be reliably provided, with a desired accuracy, as V 11 ′=V S12 −V C11  by the ADC  40 O by taking advantage of the fact that, as discussed previously, V S12 =V C12 . 
     Conversely, assuming that the ADC  40 O is faulty, so that the signal V 11 =V Cn −V C10  originally provided thereby is unreliable (“not available”), as a result of swapping, the corresponding measurement can be reliably provided, with a desired accuracy, as V 12 ′=V C1 −V C10  by the ADC  40 E. 
     The block  208  is exemplary of the possibility for operation of the system being continued with cell swapping so that precise signal conversion is maintained for the cells with UV/OV information continued to be derived therefrom (in a manner known per se to those of skill in the art) in compliance with safety specifications. 
     This is advantageous in automotive applications, for instance, insofar as vehicle operation (travel capability, for instance) can be adequately maintained at the tolerable cost of computational time increased until a service intervention is performed (block  210  in  FIG. 7 ) with normal operation restored. 
     In one or more embodiments, a swapping action as discussed previously can take place under the control of the logic circuit L (a microcontroller, for instance). 
     For instance, acts as exemplified in blocks  204  to  210  may involve, as a result of a fault being detected (via a BIST as discussed previously, for instance): 
     deleting the conversion and the diagnosis error related to a faulty processing chain (ADC, for instance), 
     saving the information about the cells and merged in a step (possibly enabled via SPI) wherein a swap function is activated as discussed previously, 
     once the swap function is enabled, the information is deleted except for the cell under analysis, with fault eventually read and cleared and routine operation started again. 
       FIGS. 5 and 6  (where cells such as Cell 2  and Cell 11 , Cell 12  and Cell 13  are not visible for compactness) are further exemplary of the cell swapping procedure discussed in the foregoing. 
     For instance,  FIG. 5  is exemplary of case where an error (damaged ADC, for instance) is detected affecting the sensing action between the pins C 3  and C 4  (even numbered cell, Cell 4 , ADC_ 4 ). 
     As a result (voltage) signal conversion will be not be available for C 4 -C 3  while available both for “lower” pins (C 3 -C 2 , for instance) and “higher” pins (C 5 -C 4 , C 6 -C 5 , C 7 -C 6 , C 8 -C 7 , . . . ) 
     Since an error occurring on (for instance) ADC_ 4  has been detected, conversion on ADC_ 4 , that is C 4 -C 3 , is not taken into account and the swap function is enabled. 
       FIG. 6  exemplifies that, as a result of the swapping action discussed herein, the voltage drop V diff  across C 4 -C 3  is measured on an adjacent (odd numbered) cell such as Cell 3 , using the respective ADC, namely ADC_ 3 , thus facilitating UV/OV detection (and voltage measurement) on the associated cell. 
     Stated otherwise, as a result of a self-test (however performed: see, for instance, the earlier/co-pending applications already repeatedly cited) revealing a faulty condition a swapping procedure of the cells is performed as discussed previously. 
     For instance, as already discussed in connection with  FIG. 4  (where only the cells Cell 11  and Cell 12  are exemplified in detail for simplicity): 
     under normal operating conditions, the ADC  40 E measures V 12 =V C12 −V C11  corresponding to cell Cell 12  while the ADC  40 O measures V 11 =V C11 −V C10  corresponding to cell Cell 11 ; 
     as a result of a self-test revealing a faulty condition in either one of  40 E or  40 O, in order to continue measuring UV/OV as desired, cell swapping is effected so that the ADC  40 E will be configured to measure V′ 12 =V C11 −V C10  corresponding to cell Cell 11  while the ADC  40 O will be configured to measure V′ 11 =V S12 −V C11  corresponding to cell Cell 12 . 
     In that way, the measurement no longer available from a faulty ADC ( 40 E, respectively  40 O) will be provided—with no loss in accuracy—via a neighboring ADC ( 40 O, respectively  40 E). 
     As illustrated in  FIGS. 5 and 6 , such a procedure exemplified in  FIG. 4  for the pair of cells Cell  11  and Cell 12  may be applied to other pairs of neighboring cells in the system. 
       FIG. 5  is exemplary of a condition where, during normal cell measurement, one conversion channel (for instance ADC_ 4  active between C 4  and C 3 ) is found to be faulty, via a BIST procedure, for instance. As a result, the measurement from this conversion channel (ADC, for instance) is considered not reliable (and declared “not available”, for instance). 
     Cell swapping is thus activated as exemplified in  FIG. 6  where the cell for which “normal” measurement has been declared not available is measured via an adjacent conversion channel (for instance ADC_ 3 , again active between C 4  and C 3 ). 
     In that way, the arrangement exemplified herein may continue to provide measurements for all the cells, with only an increased (doubled) time of execution. 
     This may be due, for instance, to the fact that, during operation as exemplified in  FIG. 5 , measurements for the cell are saved for cells Cell 1  to Cell 14 , except for Cell 4  (where ADC_ 4  was found to be faulty). 
     As a result of cell swapping as exemplified in  FIG. 6 , the measurement for cell Cell 4  (as provided via ADC_ 3 ) is saved, so that information for all the cells Cell 1  to Cell 14  (including Cell 4 ) becomes eventually available (with a desired accuracy, unaffected by the fault condition). 
     In one or more embodiments, the two conditions exemplified in  FIG. 5  and  FIG. 6  can be continued to be alternated, thus providing continued measurements for all the cells Cell 1  to Cell 14 . 
     In one or more embodiments, a BIST procedure can be performed for any cell Cell 1  to Cell 14 , virtually at anytime (cyclically or on demand). If the procedure reveals a failure, standard measurement and “swapping” measurement. 
     For instance, for any pair of an odd-numbered cell and a subsequent even-numbered cell (for instance Cell 11  and Cell 12  in  FIG. 4 , respectively): 
     a) during the standard measurement:
         the even-numbered ADC  40 E (ADC_ 12 ) is configured to measure V 12 =V C12 −V C11 , that is the voltage across the even-numbered cell Cell 12 , and   the odd-numbered ADC  40 O (ADC_ 11 ) is configured to measure V 11 =V C11 −V C10 , that is the voltage across the odd-numbered cell Cell 11 ,       

     b) during the “swapping” measurement:
         the even-numbered ADC  40 E (ADC_ 12 ) is configured to measure V′ 12 =V C11 −V C10 , that is the voltage across the odd-numbered cell Cell 11 , and   the odd-numbered ADC  40 O (ADC_ 11 ) is configured to measure V′ 11 =V S12 −V C11 , that is the voltage across the even-numbered cell Cell 12 .       

     One or more embodiments may thus rely on internal charge transfer paths (already) provided for balancing the cells in a battery pack in order to facilitate charge equalization between the cells. 
     One or more embodiments may be compatible with a built-in self-test (BIST) feature the verifies the adequate functionality of the V diff  sensing chains (internal analog comparators and ADCs, for instance) with a check procedure which can be automatically performed in case of a failure of either one of two cells or a battery pack as a whole, with the capability of providing corresponding (reliable) information—to an external microcontroller, for instance. 
     A method as exemplified herein may facilitate operating a control device (for instance,  10 ) in a battery management system (for instance, BMS), wherein: 
     the control device comprises an ordered sequence of charge-sensing pins (for instance, C 0  to C 14 ) arranged in a plurality of pairs (for instance, C 0 , C 1 ; C 1 , C 2 ; . . . ; C 12 , C 13 ; C 13 , C 14 ) of charge-sensing pins in an ordered sequence of odd- and even-numbered pairs of charge-sensing pins, the charge sensing pins in each pair of charge-sensing pins in the plurality of pairs (for instance, C 0 , C 1 ; C 1 , C 2 ; . . . ; C 12 , C 13 ; C 13 , C 14 ) of charge-sensing pins coupled (R LPF ) to a respective cell (for instance, Cell 1 , Cell 2 , . . . , Cell 13 , Cell 14 ) in a battery pack to sense the voltage across the respective cell, wherein each odd-numbered (for instance, C 0 , C 1 ; . . . ; C 12 , C 13 ) resp. even-numbered (for instance, C 1 , C 2 ; . . . ; C 13 , C 14 ) pair of charge-sensing pins shares a common charge sensing pin (for instance, C 1 , . . . , C 13 ) with a subsequent even-numbered pair (for instance, C 1 , C 2 ; . . . ; C 13 , C 14 ) resp. a previous odd-numbered pair (for instance, C 0 , C 1 ; . . . ; C 12 , C 13 ) of charge-sensing pins in the ordered sequence of odd- and even-numbered pairs of charge-sensing pins, 
     each odd-numbered pair (for instance, C 0 , C 1 ; . . . ; C 12 , C 13 ) of charge-sensing pins and the subsequent even-numbered pair (for instance, C 1 , C 2 ; . . . ; C 13 , C 14 ) of charge-sensing pins in the ordered sequence of odd- and even-numbered pairs of charge-sensing pins comprise a charge distribution pin (for instance, S 2 , S 4 , . . . , S 12 , . . . , S 14 ) coupled (for instance, R DIS ) to the charge sensing pin of the even-numbered pair of charge-sensing pins other than the common charge sensing pin (for instance, C 1 , . . . , C 13 ). 
     A method as exemplified herein may comprise, for an odd-numbered pair (see, for instance C 10 , C 11  in  FIG. 4 ) of charge-sensing pins and the subsequent even-numbered pair (see, for instance C 11 , C 12  in  FIG. 4 ) of charge-sensing pins in the ordered sequence of odd- and even-numbered pairs of charge-sensing pins: 
     a) sensing (see, for instance  100 ,  30 E,  40 E,  30 O,  40 O):
         a first voltage drop (for instance, V 12 ) between the charge sensing pin (for instance, C 12 ) of the subsequent even-numbered pair other than the common charge sensing pin and the common charge sensing pin (for instance, C 11 ), the first voltage drop being indicative of the voltage drop across the charge sensing pins of the subsequent even-numbered pair, and   a second voltage drop (for instance, V 11 ) between the common charge sensing pin (for instance, C 11 ) and the charge sensing pin (for instance, C 10 ) of the previous odd-numbered pair other than the common charge sensing pin, the second voltage drop being indicative of the voltage drop across the charge sensing pins of the previous odd-numbered pair,       

     b) as a result of a faulty condition detected (for instance,  202 ) in the device:
         swapping for the first voltage drop a first swapped voltage drop (for instance, V 12 ′) between the common charge sensing pin (for instance, C 11 ) and the charge sensing pin (for instance, C 10 ) of the previous odd-numbered pair other than the common charge sensing pin, wherein the first swapped voltage drop is indicative of the voltage drop across the charge sensing pins of the previous odd-numbered pair,   swapping for the second voltage drop a second swapped voltage drop (for instance, V 11 ′) between the charge distribution pin (for instance, S 12 ) coupled (for instance, via R DIS ) to the charge sensing pin (for instance, C 12 ) of the subsequent even-numbered pair other than the common charge sensing pin and the common charge sensing pin (for instance, C 11 ), wherein the second swapped voltage drop is indicative of the voltage drop across the charge sensing pins of the subsequent even-numbered pair (for instance, C 11 , C 12 ).       

     A method as exemplified herein may comprise, as a result of a faulty condition detected for either one (for instance, for either one of the ADCs  40 O,  40 E in  FIG. 4 ) of the subsequent even-numbered pair (for instance, C 11 , C 12  in  FIG. 4 ) and previous odd-numbered pair (for instance, C 10 , C 11  in  FIG. 4 ) of charge-sensing pins: 
     discarding the first voltage drop (for instance, V 12 ) resp. second voltage drop (for instance, V 11 ) for the pair of charge-sensing pins for which the faulty condition is detected (see also C 4 -C 3  discarded in  FIG. 5  due to ADC_ 4  found to be faulty), and 
     replacing the first resp. second voltage drop discarded with the first (for instance, V′ 12 ) resp. second (for instance, V′ 11 ) swapped voltage drop swapped therefor (see also C 4 -C 3  as provided by ADC_ 3 —not faulty—in  FIG. 6 ). 
     A method as exemplified herein may comprise, as a result of a faulty condition detected for a pair of charge-sensing pins in the plurality of pairs (for instance, C 0 , C 1 ; C 1 , C 2 ; . . . ; C 12 , C 13 ; C 13 , C 14 ) of charge-sensing pins in the ordered sequence of odd- and even-numbered pairs of charge-sensing pins, 
     a first act of recording (for instance, at L) the first (V 12 ) and second (V 11 ) voltage drops for the plurality of pairs of charge-sensing pins with the exception of the first (V 12 ) resp. second (V 11 ) voltage drop for the pair of charge-sensing pins for which the faulty condition is detected (see again, for instance, C 4 -C 3  discarded in  FIG. 5  due to ADC_ 4  found to be faulty), and 
     a second act of recording, for the pair of charge-sensing pins for which the faulty condition is detected, the first resp. second swapped voltage drop swapped for the first resp. second voltage drop for the pair of charge-sensing pins for which the faulty condition is detected (see again C 4 -C 3  as provided by ADC_ 3 —not faulty—in  FIG. 6 ). 
     A method as exemplified herein may comprise alternating the second act of recording to the first act of recording, so that reliable measures can be obtained for all the pin pairs (that is, for all the cells) although with a measurement time increased (doubled). 
     A method as exemplified herein may comprise swapping the first resp. second swapped voltage drop for the first resp. second voltage drop between the first act of recording and the second act of recording. 
     A method as exemplified herein may comprise providing first (for instance,  30 E,  40 E) and second (for instance,  30 O,  40 O) signal sensing circuitry configured to sense the first voltage drop and the second voltage drop wherein the first and second signal sensing circuitry have a sensing resolution (ADC resolution, for instance), wherein the sensing resolution is maintained for the first and second swapped voltage drops (as a result of the first and second swapped voltage drops being likewise sensed via the first and second signal sensing circuitry, in a swapped configuration). 
     A method as exemplified may comprise applying undervoltage and/or overvoltage detection to the first resp. second swapped voltage drop. 
     A control device (for instance,  10 ) for a battery management system (for instance, BMS) as exemplified herein may comprise: 
     an ordered sequence of charge-sensing pins (C 0  to C 14 ) arranged in a plurality of pairs (C 0 , C 1 ; C 1 , C 2 ; . . . ; C 12 , C 13 ; C 13 , C 14 ) of charge-sensing pins in an ordered sequence of odd- and even-numbered pairs of charge-sensing pins, the charge sensing pins in each pair of charge-sensing pins in the plurality of pairs (C 0 , C 1 ; C 1 , C 2 ; . . . ; C 12 , C 13 ; C 13 , C 14 ) of charge-sensing pins configured to be coupled (R LPF ) to a respective cell (Cell 1 , Cell 2 , . . . , Cell 13 , Cell 14 ) in a battery pack (BP) to sense the voltage across the respective cell, wherein each odd-numbered (for instance, C 10 , C 11 ) resp. even-numbered (for instance, C 11 , C 12 ) pair of charge-sensing pins shares a common charge sensing pin (for instance, C 1 , . . . , C 13 ) with the subsequent even-numbered pair resp. previous odd-numbered pair of charge-sensing pins in the ordered sequence of odd- and even-numbered pairs of charge-sensing pins, 
     wherein each odd-numbered pair of charge-sensing pins and the subsequent even-numbered pair charge-sensing pins in the ordered sequence of odd- and even-numbered pairs of charge-sensing pins comprise a charge distribution pin (for instance, S 2 , S 4 , . . . , S 14 ) configured to be coupled (for instance, via R DIS ) to the charge sensing pin of the even-numbered pair of charge-sensing pins other than the common charge sensing pin, 
     wherein the device may comprise a processor circuit (for instance, L) as well as signal sensing circuitry (for instance,  30 E,  30 O;  40 E,  40 A), 
     wherein the device is configured to operate with the method as exemplified herein, and comprises: 
     the signal sensing circuitry configurable (for instance, via the multiplexers  30 E,  30 O) to sense the first and second voltage drops (for instance, V 12 ; V 11 ) as well as the first and second swapped voltage drops (for instance, V′ 12 ; V′ 11 ), 
     the processor circuit (for instance, L) configured to sense a faulty condition detected in the device and to swap the first and second swapped voltage drops for the first and second voltage drops as a result of the faulty condition detected. 
     In a control device as exemplified herein the signal sensing circuitry may comprise, for an odd-numbered pair (for instance C 10 , C 11 ) of charge-sensing pins and the subsequent even-numbered pair (C 1 , C 2 ; . . . ; C 13 , C 14 ) of charge-sensing pins in the ordered sequence of odd- and even-numbered pairs of charge-sensing pins: 
     first signal sensing circuitry (for instance,  30 E,  40 E) configured (for instance, via the multiplexer  30 E) to be coupled:
         i) to the charge sensing pin (for instance, C 12 ) of the subsequent even-numbered pair (C 11 , C 12 ) other than the common charge sensing pin and the common charge sensing pin (for instance, C 11 ) to sense the first voltage drop (for instance, V 12 ) therebetween, and   ii) to the common charge sensing pin (for instance, C 11 ) and the charge sensing pin (for instance, C 10 ) of the previous odd-numbered pair (for instance, C 10 , C 11 ) other than the common charge sensing pin, to sense the first swapped voltage drop (for instance, V 12 ′) therebetween,       

     second signal sensing circuitry (for instance,  30 O,  40 O) configured (for instance, vie the multiplexer  30 O) to be coupled:
         i) to the common charge sensing pin (for instance, C 11 ) and the charge sensing pin (for instance, C 10 ) of the previous odd-numbered pair (for instance, C 10 , C 11 ) other than the common charge sensing pin, to sense the second voltage drop (for instance, V 11 ) therebetween,   ii) to the charge distribution pin (for instance, S 12 ) coupled (for instance, via R DIS ) to the charge sensing pin of the subsequent even-numbered pair (for instance, C 11 , C 12 ) other than the common charge sensing pin and the common charge sensing pin (C 11 ) to sense the second swapped voltage drop (for instance, V′ 11 ) therebetween.       

     An electrically powered vehicle as exemplified herein (for instance, V) may comprise: 
     a battery pack (for instance, BP) comprising a plurality of electrical battery cells (for instance, C), 
     a battery management system (for instance, BMS) coupled to the battery pack, 
     a control device (for instance,  10 ) as exemplified herein configured to control the battery management system. 
     Without prejudice to the underlying principles, the details and embodiments may vary, even significantly, with respect to what has been described by way of example only without departing from the extent of protection. 
     The extent of protection is determined by the annexed claims.