A method of determining the current sourced or sunk by a high-voltage battery of a high-voltage system of an electric vehicle

Abstract

A method (20) of determining the battery current (IBatt) sourced or sunk by a high-voltage battery (102) of a high-voltage system (10) of an electric vehicle (V) is described. The high-voltage system (10) comprises the high-voltage battery (102), an on-board charger (104), an electric heater (106), a DC-DC converter (108), an electric compressor (110) and at least one inverter (112). A first battery current value (IBatt_Raw) and a first binary signal (IBatt_Avl) indicative of whether the first battery current value (IBatt_Raw) is correctly available or not are received (302) from a battery management control unit (102). In response to the first battery current value (IBatt_Raw) being correctly available, it is determined (302) that the battery current (IBatt) sourced or sunk by the high-voltage battery (102) is equal to the first battery current value (IBatt_Raw). In response to the first battery current value (IBatt_Raw) not being correctly available, a second battery current value (IBatt_Model) is calculated (202, 204, 206, 208, 210, 402) based on a first partial current (IChrg) sourced by the on-board charger (104), a second partial current (IEAC) sunk by the electric compressor (110), a third partial current (IECH) sunk by the electric heater (106), a fourth partial current (IDCDC_HV) sunk by the DC-DC converter (108), and a fifth partial current (IInverters) sunk or sourced by the at least one inverter (112). It is determined (302) that the battery current (IBatt) sourced or sunk by the high-voltage battery (102) is equal to the second battery current value (IBatt_Model).

Description

[0001] “A method of determining the current sourced or sunk by a high- voltage battery of a high-voltage system of an electric vehicle”

[0002] ****

[0003] TEXT OF THE DESCRIPTION

[0004] Field of the invention

[0005] The present invention relates to electric vehicles equipped with a high-voltage battery, for example an 800 V battery, which supplies energy primarily to the electric powertrain (for this reason also called traction battery) and more generally to a high-voltage electrical system of the vehicle. The battery can be recharged by connection to an external charging infrastructure (so-called charging stations). Such vehicles may include battery electric vehicles (BEV) or hybrid electric vehicles (HEV).

[0006] The invention was developed with reference to the determination (or reconstruction or recovery) of the value of the current sourced or sunk by the battery in the case where the battery current signal produced by the battery control unit (e.g., by a battery management system, BMS) is not available, for example because it is not reliable.

[0007] Prior art

[0008] In modem electric vehicles, in which a high-voltage battery is present (e.g., 800 V - also referred to as " HV battery" in the present description, from high voltage) dedicated primarily to powering the powertrain and other electrical components forming part of the high-voltage electrical system (e.g., the air conditioning system for the passenger cabin, the heating and / or cooling system of the battery pack, etc.), one or more vehicle control units (e.g., the battery management system “BMS” and / or the vehicle dynamic control module “VDCM”) manage various aspects of the operation of these electrical components (e.g., propulsion management, battery charging management, heating and / or cooling function management, etc.) also based on the electrical quantities sensed in the system, including, for example, the current (sourced or sunk) of the high-voltage battery, whose value under normal conditions is known thanks to a signal produced by the BMS control unit.

[0009] In the case where the battery current signal produced by the BMScontrol unit is not available (for example, because it is not determined reliably), some vehicle functionalities that are based on battery discharge or charging may be inhibited (for example, it may be impossible to operate the powertrain to set the vehicle in movement, or to recharge the vehicle). The inhibition of these (even primary) vehicle functionalities due to the unavailability of the battery current signal provided by the BMS represents an impediment for the vehicle user.

[0010] Some documents of possible interest in this technical field are US 11817562 B2, CN 114030357 A, and CN 216016433 U.

[0011] Therefore, there is a need in the art to develop a method that allows determining (or reconstructing or recovering) the value of the current sourced or sunk by the high-voltage battery of an electric vehicle, particularly when the direct detection of this current by the BMS is not possible and / or is not sufficiently reliable, so as to allow even in such circumstances the use of the vehicle functionalities that involve charging or discharging the high-voltage battery.

[0012] Object of the invention

[0013] The object of the invention is to solve the technical problem mentioned above. In particular, the object of the invention is to provide a method for determining the value of the current sourced or sunk by the high-voltage battery of an electric vehicle, when direct detection of such a current by the vehicle's BMS control unit is not possible (for example, it is not available or is not sufficiently accurate), so as to avoid the inhibition of the vehicle functionalities that involve a discharge or charging phase of the high-voltage battery.

[0014] Summary of the invention

[0015] The object of the invention is achieved by a method having the features forming the subject of the claims that follow, which form an integral part of the technical teaching provided herein in relation to the invention.

[0016] The method can be implemented by one or more electronic control units of a vehicle, for example by the battery management system control unit (BMS) and / or by the vehicle dynamic control module (VDCM).Brief description of the figures

[0017] The invention will now be described with reference to the accompanying figures, provided by way of non-limiting example only, in which:

[0018] Figure 1 is a block diagram exemplifying a high-voltage electrical system of an electric vehicle;

[0019] Figure 2 is a block diagram illustrating the steps of a method for determining the value of the current sourced or sunk by the high-voltage battery of an electric vehicle, according to one or more embodiments of the present description;

[0020] Figure 3 is a block diagram illustrating a step of selecting the value of the current sourced or sunk by the high-voltage battery of an electric vehicle, according to one or more embodiments of the present description;

[0021] Figure 4 is a block diagram illustrating a step of calculating the value of the current sourced or sunk by the high-voltage battery of an electric vehicle, according to one or more embodiments of the present description;

[0022] Figure 5 is a block diagram illustrating some components of a charging system of an electric vehicle;

[0023] Figures 6 to 10 are block diagrams illustrating the steps of a procedure for estimating or calculating the value of the current sourced, during charging of the electric vehicle, by an on-board charger of the electric vehicle, according to one or more embodiments of the present description;

[0024] Figures 11 to 14 are block diagrams illustrating the steps of a procedure for estimating or calculating the value of the current sunk by an electric compressor of a vehicle cooling and / or refrigeration system, according to one or more embodiments of the present description;

[0025] Figure 15 is a block diagram illustrating the steps of a procedure for estimating or calculating the value of the current sunk by an electric heater of a vehicle heating system, according to one or more embodiments of the present description;

[0026] Figures 16 to 20 are block diagrams illustrating the steps of a procedure for estimating or calculating the value of the current sunk by the high-voltage side of a DC-DC converter of the high-voltage system of the electric vehicle, according to one or more embodiments of the present description;Figures 21 to 27 are block diagrams illustrating the steps of a procedure for estimating or calculating the value of the current sunk or sourced by one or more inverters of the electric vehicle, according to one or more embodiments of the present description; and

[0027] Figure 28 is a block diagram illustrating the phases of a method for determining the value of the current sourced or sunk by the high-voltage battery of an electric vehicle, according to one or more embodiments of the present description.

[0028] Detailed description

[0029] The current sourced or sunk by the high-voltage battery is a signal that, under normal operating conditions of the vehicle, is measured and communicated to other vehicle control units by the battery control unit (or BMS control unit). This signal is used in various control algorithms to manage various vehicle functionalities (e.g., charging of the high-voltage battery, vehicle propulsion, thermal management of vehicle components such as heating and cooling of the battery pack and / or passenger cabin). In order to be able to use such functionalities (even possibly in a "derated" or degraded mode, i.e., limited) it is appropriate to be able to determine (indirectly) the value of the current sourced or sunk by the high-voltage battery when the corresponding signal is not available from the BMS control unit.

[0030] Figure 1 is a block diagram exemplifying a certain number of electrical components that can be included in the high-voltage system 10 of an electric vehicle V, and the current flows that can occur between such electrical components. The system 10 comprises a high-voltage battery 102, an on-board charger 104, an electric heater 106 (for example, for heating a coolant of a vehicle thermal conditioning system), a DC-DC converter 108 (for example, for powering low-voltage loads using the energy stored in the high-voltage battery 102), a compressor 110 (e.g., for compressing the refrigerant of the conditioning system), and one or more inverters 112 (for example, four inverters 1121, 1122, 1123, 1124) each driving a respective electric motor (e.g., four electric motors) of the vehicle V.

[0031] In the analysis of the current flows in the high-voltage system 10, thecharger 104 operates only as a current source, while the heater 106, the DC-DC converter 108 and the compressor 110 operate only as current sinks (i.e., they are electrical loads). The inverters 112 can operate as current sinks from the battery during vehicle propulsion phases, or as current sources towards the battery and other components during vehicle regenerative braking phases. The high-voltage battery 102 is a passive component that can sink or source current based on the balance of the current flows between the other components of the system 10. Furthermore, the charger 104 and the inverters 112 usually never operate at the same time: in fact, during the vehicle charging phase (via connection to an external charging infrastructure) the inverters 112 are disabled, and when the inverters 112 are operational the charger 104 is disabled because the vehicle is not connected to the external charging infrastructure. The flow of current sourced or sunk by the high-voltage battery 102 is equal to the sum of the current flows of all the other components of the system 10, according to Kirchhoffs current law.

[0032] Figure 2 is a block diagram illustrating the steps of a method 20 for determining the value of the current IBattsourced or sunk by the high-voltage battery 102 of the electric vehicle V, according to one or more embodiments of the present description. In a step 202, the current IChrgsourced by the onboard charger 104 is determined. In a step 204, the current IEACsunk by the electric compressor 110 is determined. In a step 206, the current IECHsunk by the electric heater 106 is determined. In a step 208, the current IInverterssourced or sunk by the inverters 112 is determined. In a step 210, the current IDCDC_HVsunk by the DC-DC converter 108 (in particular, sunk by the high-voltage side of the DC-DC converter 108) is determined. In a step 212, the current IBattsourced or sunk by the high-voltage battery 102 is determined as a function of the currents IChrg, IEAC, IECH, IInverters, and IDCDC_HV. It will be noted that the steps (or blocks of operations) 202 to 210 can be executed in any order, or even simultaneously.

[0033] The sequence of operations executed in step 212 for determining the current IBatt sourced or sunk by the high-voltage battery 102 will now be described first, with reference to the block diagrams of Figures 3 and 4.

[0034] Substantially, block 302 illustrated in Figure 3 operates as a selector that receives at a first input the battery current value IBatt_Rawmeasured bythe BMS control unit and at a second input a battery current value IBattjviodei calculated (otherwise said, estimated) as described in detail below, and is controlled by a binary signal IBatt_Avlthat indicates whether the current value IBatt_Rawmeasured by the BMS control unit is correctly available or not. In particular, the signal IBatt_Avlis produced by the BMS control unit itself. The signal IBatt_Avlis asserted (e.g., set to 1) when the current signal IBatt_Rawmeasured by the BMS is correctly available, and is de-asserted (e.g., set to 0) when the current signal IBatt_Rawmeasured by the BMS is not correctly available. If the signal IBatt_Avlis asserted, the battery current value IBattcalculated by the method 20 is set equal to the value IBatt_Rawmeasured by the BMS control unit. If instead the signal IBatt_Avlis de-asserted, the battery current value IBattcalculated by the method 20 is set equal to the calculated current value IBatt_Model.

[0035] The current value IBatt_Modelis calculated (otherwise said, estimated) as illustrated in Figure 4: in particular, the current IBatt_Modelis equal to the sum (with sign, according to Kirchhoff's current law) of the currents of the electrical components forming part of the high-voltage system 10, namely the current IChrgsourced by the on-board charger 104, the current IDCDC_HVsunk by the high-voltage side of the DC-DC converter 108, the current IEACsunk by the compressor 110, the current IECHsunk by the heater 106, and the current IInverterssourced or sunk overall by the inverters 112. The current of the high-voltage battery 102 is conventionally considered positive when it leaves the battery (i.e., it is sourced by the battery). The current of the onboard charger 104 is conventionally considered positive when it leaves the charger (i.e., it is sourced by the charger). The currents of the DC-DC converter 108, the compressor 110 and the heater 106 are conventionally considered positive when they enter the respective components (i.e., they are sunk by the loads). The current of the inverters 112 is conventionally considered positive when it enters the inverters (i.e., it is sunk by the inverters). Therefore, the summing block 402 illustrated in Figure 4 calculates the value of the current IBatt_Modelby summing together the currents IDCDC_HV, IEAC, IECHand IInverters, and subtracting from this sum the current IChrg. Furthermore, when the vehicle is in a charging phase (and therefore normally the current IChrgof the on-board charger assumes a value different from zero) the inverters 112 are disabled and therefore their currentIInvertersis equal to zero, while when the vehicle is in a driving phase (and therefore normally the current IInvertersof the inverters assumes a value different from zero) the charger 104 is disabled and therefore its current IChrgis equal to zero.

[0036] The sequence of operations executed in step 202 for determining the current Ichrg sourced by the on-board charger 104 will now be described with reference to the block diagrams of Figures 5 to 10.

[0037] Figure 5 is a block diagram exemplifying the three main electrical components of a charging system 50 for the electric vehicle V, and the corresponding flow of the charging current Ichrg. In particular, the charging system 50 comprises a charging infrastructure 502 (charging column or station) external to the vehicle V, a charging port 504 of the vehicle V, and a converter 506 of the vehicle V (e.g., comprising an AC-DC converter, a boost-type DC-DC converter, and a DC bypass). The converter 506 absorbs current from the external infrastructure 502 and transfers it to the vehicle V (e.g., to the battery 102) as current Ichrg.

[0038] The block 602 for providing the value of the charger current Ichrg illustrated in Figure 6 operates as a selector that receives at a first input a current value IChrgConverter_Rawmeasured directly by the converter 506 and at a second input a current value IChrgConverter_Modelcalculated as described in detail below, and is controlled by a binary signal IChrgConverter_Avlthat indicates whether the current value IChrgConverter_Rawmeasured by the converter 506 is correctly available or not. In particular, the signal IChrgConverter_Avlis produced by the converter 506. The signal IChrgConverter_Avlis asserted (e.g., set to 1) when the current value IChrgConverter_Rawmeasured by the converter 506 is correctly available, and is de-asserted (e.g., set to 0) when the current value IChrgConverter_Rawmeasured by the converter 506 is not correctly available. If the signal IChrgConverter_Avlis asserted, the value of the current IChrgsourced by the on-board charger is set equal to the measured value IChrgConverter_Raw. If instead the signal IChrgConverter_Avlis de-asserted, the value of the current IChrgsourced by the on-board charger is set equal to the calculated current value IChrgConverter_Model.

[0039] The block 702 for providing the calculated value of the charger current IChrgConverter_Modelillustrated in Figure 7 operates as a selector that receives at a first input a current value IChrgStationConvertedcalculated asdescribed in detail below (and indicative of the current sourced by the onboard charger, calculated as a function of the current sourced by the charging station) and at a second input a null current value (or zero), and is controlled by a binary signal IChrgStationConverted_Avlthat indicates whether the current value IChrgStationConvertedis correctly available or not. In particular, the signal IChrgStationConverted_Avlis produced as illustrated below with reference to Figure 10. The signal IChrgStationConverted_Avlis asserted (e.g., set to 1) when the value of the current IChrgStationConvertedis correctly available, and is de-asserted (e.g., set to 0) when the value of the current IChrgStationConvertedis not correctly available. If the signal IChrgStationConverted_Avlis asserted, the calculated value IChrgConverter_Modelof the current sourced by the on-board charger is set equal to the value IChrgStationConverted. If instead the signal IChrgStationConverted_Avlis de-asserted, the calculated value IChrgConverter_Modelof the current sourced by the on-board charger is set equal to zero.

[0040] The value of the current Ichrgstationconverted sourced by the on-board charger and calculated as a function of the current sourced by the charging station is calculated as illustrated in Figure 8. In particular, the current IChrgStationConvertedis equal to the product of the current IChrgStation_Rawsourced by the charging station (whose value is measured and communicated by the charging station) and the output voltage VChrgStationof the charging station (whose value is measured and communicated by the charging station) and the efficiency ηChrgConverterof the converter 506 (whose value is calculated as described below), divided by the output voltage VChrgConverterof the converter 506 (whose value is measured and communicated by the converter 506). In fact, the output voltage VChrgConverterof the converter 506 is equal to the voltage of the high-voltage battery 102, while the output voltage VChrgStationof the charging station could have a different value.

[0041] The value of the efficiency ηChrgConverterof the converter 506 is calculated as illustrated in graph 902 of Figure 9. Figure 9 qualitatively illustrates the trend of the value of the efficiency ηChrgConverterof the converter 506 determined based on the current IChrgsourced by the on-board charger 104 (determined at the previous iteration of the method) for different values of the output voltage VChrgConverterof the converter 506, specifically for four different values VChrgConverter1, VChrgConverter2, VChrgConverter3, VChrgConverter4. Generally, the value of the efficiency ηChrgConverterof the converter 506decreases (e.g., linearly, as exemplified in Figure 9) as the current Ichrg sourced by the on-board charger 104 increases. Furthermore, generally the value of the efficiency r / chrgconverter of the converter 506 decreases as the output voltage Vchrgcomerter of the converter 506 decreases: thus, in the example of Figure 9, it could be VChrgConverter1> VChrgConverter2> VChrgConverter3> VChrgConverter4. Therefore, in step 202, the method comprises sensing the current IChrgsourced by the on-board charger 104 (as determined at the previous iteration of the method) and sensing the output voltage VChrgConverterof the converter 506, and determining the value of the efficiency ηChrgConverterof the converter 506 according to the dependency laws illustrated in Figure 9, which can be implemented using one or more stored characteristic maps (e.g., implemented as analytical functions, piecewise functions, or look-up tables).

[0042] As anticipated, the binary signal lchrgstationconverted_Avi that indicates whether the current value Ichrgstationconverted is correctly available or not is produced as exemplified by the diagram of Figure 10. Substantially, the binary signal IChrgStationConverted_Avlis produced at the output of an AND logic gate 1002 so as to be asserted if the three binary signals IChrgStation_Avl, VChrgStation_Avland VChrgConverter_Avlare asserted, which indicate respectively that: (i) the value of the current IChrgStation_Rawsourced by the charging station is available insofar as it is measured and communicated correctly to the vehicle by the charging station, (ii) the value of the output voltage Vchrgstation of the charging station is available insofar as it is measured and communicated correctly to the vehicle by the charging station, and (iii) the value of the output voltage Vchrgcomerter of the converter 506 is available insofar as it is measured and communicated correctly by the converter 506.

[0043] The sequence of operations executed in step 204 for determining the current IEAC sunk by the electric compressor 110 will now be described with reference to the block diagrams of Figures 11 to 14.

[0044] The block 1102 for providing the value of the current IEAC sunk by the compressor illustrated in Figure 11 operates as a selector that receives at a first input a current value IEAC_Rawmeasured directly by the compressor 110 and at a second input a current value IEAC_Modelcalculated as described in detail below, and is controlled by a binary signal IEAC_Avlthat indicates whether the current value IEAC_Rawmeasured by the compressor 110 iscorrectly available or not. In particular, the signal IEAC_Avlis produced by the compressor 110. The signal IEAC_AVI is asserted (e.g., set to 1) when the current value lEAc_Raw measured by the compressor 110 is correctly available, and is de-asserted (e.g., set to 0) when the current value lEAc_Raw measured by the compressor 110 is not correctly available. If the signal IEAC_AVI is asserted, the value of the current IEAC sunk by the compressor is set equal to the measured value lEAc_Raw. If instead the signal IEAC_AVI is deasserted, the value of the current IEAC sunk by the compressor is set equal to the calculated current value lEAcjviodei.

[0045] The block 1202 for providing the calculated value of the compressor current IEAC_Modelillustrated in Figure 12 operates as a selector that receives at a first input a raw current value IEAC_Model_Rawsunk by the compressor calculated as described in detail below (with reference to Figure 13) and at a second input a null current value (or zero), and is controlled by a binary signal IEAC_Model_Avlthat indicates whether the raw current value IEAC_Model_Rawsunk by the compressor is correctly available or not. In particular, the signal IEAC_Model_Avlis produced as illustrated below with reference to Figure 14. The signal IEAC_Model_Avlis asserted (e.g., set to 1) when the value of the current IEAC_Model_Rawis correctly available, and is de-asserted (e.g., set to 0) when the value of the current IEAC_Model_Rawis not correctly available. If the signal IEAC_Model_Avlis asserted, the calculated value of the current IEAC_Modelsunk by the compressor is set equal to the raw value IEAC_Model_Raw. If instead the signal IEAC_Model_Avlis de-asserted, the calculated value of the current IEAC_Modelsunk by the compressor is set equal to zero.

[0046] The raw value of the current lEAcjviodei_Raw sunk by the compressor is calculated as illustrated in Figure 13. In particular, the raw value of the current lEAcjviodei_Raw sunk by the compressor is obtained by dividing an estimated value Q ’EAC of the electrical power sunk by the motor of the compressor 110 by the value VEAC of the voltage of the motor of the compressor 110 (measured and communicated by the compressor 110), as exemplified by the division block 1304. The estimated value ’EAC of the electrical power sunk by the motor of the compressor 110 is instead calculated as indicated by graph 1302. Graph 1302 of Figure 13 qualitatively illustrates the trend of the electrical power Q’EAC of the compressor 110 determined based on the rotational speed IIEAC of the compressor 110(measured and communicated by the compressor 110) for different values of the refrigerant pressure PRef (measured at the outlet of the compressor 110), specifically for four different values PRen, PRef2, PRef3, PRef4. Generally, the value of the electrical power Q’EAC of the compressor 110 increases (e.g., linearly, as exemplified in Figure 13) as the rotational speed DEAC of the compressor 110 increases. Furthermore, generally the value of the electrical power Q’EAC of the compressor 110 increases as the refrigerant pressure PRef increases: thus, in the example of Figure 13, it could be PRef1 > PRef2 > PRef3 > PRef4. Therefore, in step 204, the method comprises sensing the rotational speed DEAC of the compressor 110 and sensing the refrigerant pressure PRef, and determining the value of the electrical power ’EAC of the compressor 110 according to the dependency laws illustrated in graph 1302 of Figure 13, which can be implemented using one or more stored characteristic maps (e.g., implemented as analytical functions, piecewise functions, or look-up tables).

[0047] As anticipated, the binary signal lEAc_Modei_Avi that indicates whether the value of the current lEAc_Modei_Raw is correctly available or not is produced as exemplified by the diagram of Figure 14. Substantially, the binary signal I EAc_Modei_Avi is produced at the output of an AND logic gate 1402 so as to be asserted if the three binary signals PRef_Avi, VEAC_AVI and DEAC_AVI are asserted, which indicate respectively that: (i) the value of the refrigerant pressure PRef is available insofar as it is measured and communicated correctly at the outlet of the compressor 110, (ii) the value of the voltage VEAC of the motor of the compressor 110 is available insofar as it is measured and communicated correctly by the compressor 110, and (iii) the value of the rotational speed DEAC of the compressor 110 is available insofar as it is measured and communicated correctly by the compressor 110.

[0048] The sequence of operations executed in step 206 for determining the current IECH sunk by the heater 106 will now be described with reference to the block diagram of Figure 15. The block 1502 for providing the value of the current IECH sunk by the heater 106 operates as a selector that receives at a first input the current value lECH_Raw measured by the heater 106 and at a second input a null current value (or zero), and is controlled by a binary signal IECH_AVI that indicates whether the current value lECH_Raw measured by the heater 106 is correctly available or not. In particular, the signal IECH_AVIis produced by the heater 106. The signal IECH_AVI is asserted (e.g., set to 1) when the current value lECH_Raw measured by the heater 106 is correctly available, and is de-asserted (e.g., set to 0) when the current value lECH_Raw measured by the heater 106 is not correctly available. If the signal IECH_AVI is asserted, the value of the current IECH sunk by the heater is set equal to the measured value lECH_Raw. If instead the signal IECH_AVI is de-asserted, the value of the current IECH sunk by the heater is set equal to zero.

[0049] The sequence of operations executed in step 210 for determining the current IDCDC_HV sunk by the high-voltage side of the DC-DC converter 108 will now be described with reference to the block diagrams of Figures 16 to 20.

[0050] The block 1602 for providing the value of the current IDCDC_HV sunk by the high-voltage side of the DC-DC converter illustrated in Figure 16 operates as a selector that receives at a first input a current value lDCDc_Hv_Raw measured directly by the DC-DC converter 108 on the high-voltage side and at a second input a current value lDCDc_Hv_Modei calculated as described in detail below, and is controlled by a binary signal IDCDC_HV_AVI that indicates whether the current value IDCDC_HV_Raw measured by the DC-DC converter 108 on the high-voltage side is correctly available or not. In particular, the signal IDCDC_HV_AVI is produced by the DC-DC converter 108. The signal IDCDC_HV_AVI is asserted (e.g., set to 1) when the current value lDCDc_Hv_Raw measured by the DC-DC converter 108 on the high-voltage side is correctly available, and is de-asserted (e.g., set to 0) when the current value lDCDc_Hv_Raw measured by the DC-DC converter 108 on the high-voltage side is not correctly available. If the signal IDCDC_HV_AVI is asserted, the value of the current IDCDC_HV sunk by the DC-DC converter is set equal to the measured value lDCDc_Hv_Raw. If instead the signal IDCDC_HV_AVI is deasserted, the value of the current IDCDC_HV sunk by the DC-DC converter is set equal to the calculated current value lDCDc_Hv_Modei.

[0051] The block 1702 for providing the calculated value of the current on the high-voltage side of the DC-DC converter lDCDc_Hv_Modei illustrated in Figure 17 operates as a selector that receives at a first input a raw current value lDCDc_Hv_Modei_Raw sunk by the DC-DC converter calculated as described in detail below (with reference to Figure 18) and at a second input a null current value (or zero), and is controlled by a binary signallDCDc_Hv_Modei_Avi that indicates whether the raw current value lDCDc_Hv_Modei_Raw sunk by the DC-DC converter is correctly available or not. In particular, the signal lDCDc_Hv_Modei_Avi is produced as illustrated below with reference to Figure 20. The signal lDCDc_Hv_Modei_Avi is asserted (e.g., set to 1 ) when the raw value of the current lDCDc_Hv_Modei_Raw sunk by the DC-DC converter is correctly available, and is de-asserted (e.g., set to 0) when the raw value of the current lDCDc_Hv_Modei_Raw sunk by the DC-DC converter is not correctly available. If the signal lDCDc_Hv_Modei_Avi is asserted, the calculated value of the current lDCDc_Hv_Modei sunk by the DC-DC converter is set equal to the value lDCDc_Hv_Modei_Raw. If instead the signal I DCDc_Hv_Modei_Avi is de-asserted, the calculated value of the current I DCDc_Hv_Modei sunk by the DC-DC converter is set equal to zero.

[0052] The raw value of the current lDCDc_Hv_Modei_Raw sunk by the high-voltage side of the DC-DC converter is calculated as illustrated in Figure 18. In particular, the current lDCDc_Hv_Modei_Raw is equal to the product of the current lDCDc_Lv_Raw sourced by the low-voltage side of the DC-DC converter (whose value is measured and communicated by the DC-DC converter 108) and the voltage VDCDC_LV on the low-voltage side of the DC-DC converter (whose value is measured and communicated by the DC-DC converter 108), divided by the efficiency r / DCDc of the DC-DC converter 108 (whose value is calculated as described below with reference to Figure 19) and further divided by the voltage VDCDC_HV on the high-voltage side of the DC-DC converter (whose value is measured and communicated by the DC-DC converter 108). In fact, the voltage VDCDC_HV on the high-voltage side of the DC-DC converter 108 is equal to the voltage of the high-voltage battery 102.

[0053] The value of the efficiency r / DCDc of the DC-DC converter 108 is calculated as illustrated in graph 1902 of Figure 19. Figure 19 qualitatively illustrates the trend of the value of the efficiency r / DCDc of the DC-DC converter 108 determined as a function of the current lDCDc_Lv_Raw sourced by the low-voltage side of the DC-DC converter 108 for different values of the voltage VDCDC_LV on the low-voltage side of the DC-DC converter 108, specifically for four different values VDCDC_LVI, VDCDC_LV2, VDCDC_LV3, VDCDC_LV4. Generally, the value of the efficiency r / DCDc of the DC-DC converter 108 decreases (e.g., linearly, as exemplified in Figure 19) as the current lDCDc_Lv_Raw sourced by the low-voltage side of the DC-DC converter108 increases. Furthermore, generally the value of the efficiency I DCDC of the DC-DC converter 108 decreases as the voltage VDCDC_LV on the low-voltage side of the DC-DC converter 108 decreases: thus, in the example of Figure 19, it could be VDCDC_LVI > VDCDC_LV2 > VDCDC_LV3 > VDCDC_LV4. Therefore, in step 210, the method comprises sensing the current lDCDc_Lv_Raw sourced by the low-voltage side of the DC-DC converter 108 and sensing the voltage VDCDC_LV on the low-voltage side of the DC-DC converter 108, and determining the value of the efficiency r / DCDc of the DC-DC converter 108 according to the dependency laws illustrated in Figure 19, which can be implemented using one or more stored characteristic maps (e.g., implemented as analytical functions, piecewise functions, or look-up tables).

[0054] As anticipated, the binary signal lDCDc_Hv_Modei_Avi that indicates whether the current value lDCDc_Hv_Modei is correctly available or not is produced as exemplified by the diagram of Figure 20. Substantially, the binary signal lDCDc_Hv_Modei_Avi is produced at the output of an AND logic gate 2002 so as to be asserted if the three binary signals IDCDC_LV_AVI, VDCDC_LV_AVI and VDCDC_HV_AVI are asserted, which indicate respectively that: (i) the value of the current lDCDc_Lv_Raw sourced by the low-voltage side of the DC-DC converter 108 is available insofar as it is measured and communicated correctly by the DC-DC converter 108, (ii) the value of the voltage VDCDC_LV on the low-voltage side of the DC-DC converter 108 is available insofar as it is measured and communicated correctly by the DC-DC converter 108, and (iii) the value of the voltage VDCDC_HV on the high-voltage side of the DC-DC converter 108 is available insofar as it is measured and communicated correctly by the DC-DC converter 108.

[0055] The sequence of operations executed in step 208 for determining the overall current / inverters sunk or sourced by the inverters 112 will now be described with reference to the block diagrams of Figures 21 to 27. In this case, reference will be made to an example wherein the vehicle V comprises four electric motors and thus four inverters 112; it will be understood, however, that in different embodiments the number of inverters can be different, lower or higher than four (even only one).

[0056] As exemplified by the summing block 2102 of Figure 21, the overall current / inverters sunk or sourced by the inverters 112 (i.e., sunk duringpropulsion phases or sourced during regenerative braking phases) is equal to the sum of the individual currents hnverterj (with i = 1, N where N is the total number of inverters) sunk or sourced by each inverter 112, i.e., in the Case Of four inverters one has / inverters=llnverter_1 + llnverter_2 + llnverter_3 + I inverter_4. In the case of a single inverter, obviously, one has / inverters=hnverter_ i.

[0057] The block 2202 for providing the value of the current hnverterj sunk or sourced by a generic i-th inverter 112 illustrated in Figure 22 operates as a selector that receives at a first input a current value I inverter j_Raw measured by the i-th inverter 112 and at a second input a current value hnverterjjiodei calculated as described in detail below, and is controlled by a binary signal hnverterj_Avi that indicates whether the current value hnverterj_Raw measured by the i-th inverter 112 is correctly available or not. In particular, the signal hnverterj_Avi is produced by the i-th inverter 112. The signal I lnverterJ_Avl is asserted (e.g., set to 1 ) when the current value I inverter j_Raw measured by the i-th inverter 112 is correctly available, and is de-asserted (e.g., set to 0) when the current value I inverter j_Raw measured by the i-th inverter 112 is not correctly available. If the signal hnverterj_Avi is asserted, the value of the current hnverter sunk or sourced by the i-th inverter is set equal to the measured value hnverterj_Raw. If instead the signal hnverterj is de-asserted, the value of the current hnverterj sunk or sourced by the i-th inverter is set equal to the calculated current value hnverterjjviodei.

[0058] The block 2302 for providing the calculated value of the current hnverterj_Modei sunk or sourced by the i-th inverter illustrated in Figure 23 operates as a selector that receives at a first input a raw current value of the i-th inverter hnverterjjviodei_Raw calculated as described in detail below (with reference to Figures 24 to 26) and at a second input a null current value (or zero), and is controlled by a binary signal hnverterjjviodei_Avi that indicates whether the raw current value of the i-th inverter hnverterjjviodei_Raw is correctly available or not. In particular, the signal hnverterjjviodei_Avi is produced as illustrated below with reference to Figure 27. The signal llnverterJJVIodel_Avl is asserted (e.g., set to 1) when the value of the current llnverterJ_IVIodel_Raw is correctly available, and is de-asserted (e.g., set to 0) when the value of the current hnverterjjviodei_Raw is not correctly available. If the signal hnverterj_Modei_Avi is asserted, the calculated value of the current hnverterjjviodei sunk or sourced by the i-th inverter is set equal to the raw valuellnverter_i_Model_Raw. If instead the signal IInverter_i_Model_Avl is de-asserted, the calculated value of the current IInverter_i_Model sunk or sourced by the i-th inverter is set equal to zero.

[0059] The raw current value I inverter j_Modei_Raw sunk or sourced by the i-th inverter is calculated as illustrated in Figures 24 to 26. In particular, the raw current value of the i-th inverter I inverter j_Modei_Raw is obtained by dividing an estimated value Q'inverterjjviodei of the electrical power sunk or sourced (depending on whether one is in a propulsion or regenerative phase) by the i-th inverter 112 by the value Vinverterj of the voltage of the i-th inverter 112 (measured and communicated by the i-th inverter 112), as exemplified by the division block 2402. The estimated value Q'inverter jviodei of the electrical power sunk or sourced by the i-th inverter 112 is provided at the output of a selector block 2404, which determines in fact whether one is in a propulsion or regenerative phase. The block 2404 receives at a first input an estimated value of propulsion electrical power (sunk) Q'inverterjjviodeiPrp of the i-th inverter calculated by a block 2406 and at a second input an estimated value of regenerative electrical power (sourced) Q‘ inverter jjviodeiRgn of the i-th inverter calculated by a block 2408, and is controlled by a binary signal Prpi that indicates whether the i-th inverter is operating in propulsion or in generation. In particular, the signal Prpi is asserted (e.g., set to 1) when the torque T otorj of the i-th motor (driven by the i-th inverter) and the rotational speed mviotorj of the i-th motor have the same sign (i.e., the i-th inverter is operating in propulsion), and is de-asserted (e.g., set to 0) when the torque TMotorj of the i-th motor and the rotational speed nMotorj of the i-th motor have different signs (i.e., the i-th inverter is operating in regeneration). If the signal Prpi is asserted, the estimated value Q'inverterjjviodei of the (sunk) electrical power of the i-th inverter 112 is set equal to the estimated value of propulsion electrical power Q' inverter jjviodeiprp. If instead the signal Prpi is deasserted, the estimated value Q'inverterjjviodei of the (sourced) electrical power of the i-th inverter 112 is set equal to the estimated value of regenerative electrical power Q'inverterjjviodeiRgn. The estimated value of propulsion electrical power Q' inverter jjviodeiprp sunk by the i-th inverter 112 is calculated in a multiplication / division block 2406 as the product of the torque T otorj of the i-th motor (driven by the i-th inverter), whose value is measured and communicated by the i-th motor, times the rotational speed nMotorj ofthe i-th motor, whose value is measured and communicated by the i-th motor, divided by the efficiency qinverterj of the i-th inverter 112 (whose value is calculated as described below with reference to Figure 26) and further divided by the efficiency i Motorj of the i-th motor (whose value is calculated as described below with reference to Figure 25). The estimated value of regenerative electrical power Q'inverterjjviodeiRgn sourced by the i-th inverter 112 is calculated in a multiplication block 2408 as the product of the torque TMotorj of the i-th motor (driven by the i-th inverter), the rotational speed r)Motor_i of the i-th motor, the efficiency qinverterj of the i-th inverter 112 and the efficiency i Motorj of the i-th motor.

[0060] The efficiency i Motorj of the i-th motor can be estimated as indicated by graph 2502 of Figure 25. The graph 2502 of Figure 25 qualitatively illustrates the trend of the efficiency i Motorj of the i-th motor determined based on the rotational speed nMotorj of the i-th motor (measured and communicated by the i-th motor) for different values of the torque TMotorj of the i-th motor (measured and communicated by the i-th motor), specifically for four different values otor _i, otor _2, otor _3, otor _4. Generally, the value of the efficiency i Motorj of the i-th motor increases, reaches a maximum value and then decreases as the rotational speed nMotorj of the i-th motor increases. Furthermore, generally the value of the efficiency i Motorj of the i-th motor depends on the torque T otorj of the i-th motor. Therefore, in step 208, the method comprises sensing the rotational speed nMotorj of the i-th motor and sensing the torque TMotorj of the i-th motor, and determining the value of the efficiency i Motorj of the i-th motor according to the dependency laws illustrated in graph 2502 of Figure 25, which can be implemented using one or more stored characteristic maps (e.g., implemented as analytical functions, piecewise functions, or look-up tables).

[0061] The efficiency qinverterj of the i-th inverter can be estimated as indicated by graph 2602 of Figure 26. The graph 2602 of Figure 26 qualitatively illustrates the trend of the efficiency qinverterj of the i-th inverter determined as a function of the rotational speed nMotorj of the i-th motor (measured and communicated by the i-th motor) for different values of the torque TMotorj of the i-th motor (measured and communicated by the i-th motor), specifically for four different values TMotorj i, TMotorj_2, TMotorj s, TMotorj_4. Generally, the value of the efficiency qinverterj of the i-th inverterincreases, reaches a maximum value and then decreases as the rotational speed mviotor_i of the i-th motor increases. Furthermore, generally the value of the efficiency qinverterj of the i-th inverter depends on the torque T otorj of the i-th motor. Therefore, in step 208, the method comprises sensing the rotational speed nMotorj of the i-th motor and sensing the torque TMotorj of the i-th motor, and determining the value of the efficiency qinverterj of the i-th inverter according to the dependency laws illustrated in graph 2602 of Figure 26, which can be implemented using one or more stored characteristic maps (e.g., implemented as analytical functions, piecewise functions, or look-up tables).

[0062] As anticipated, the binary signal I inverter j_Modei_Avi that indicates whether the raw current value of the i-th inverter I inverter j_Modei_Raw is correctly available or not is produced as exemplified by the diagram of Figure 27. Substantially, the binary signal I inverter j_Modei_Avi is produced at the output of an AND logic gate 2702 so as to be asserted if the three binary signals otor _Avi, riMotor _Avi and Vinverter _Avi are asserted, which indicate respectively that: (i) the value of the torque T otor of the i-th motor is available insofar as it is measured and communicated correctly by the i-th motor, (ii) the value of the rotational speed nMotorj of the i-th motor is available insofar as it is measured and communicated correctly by the i-th motor, and (iii) the value of the voltage Vinverterj of the i-th inverter 112 is available insofar as it is measured and communicated correctly by the i-th inverter 112.

[0063] Therefore, as exemplified in Figures 2 to 27, the idea of the method is that of determining the value of the current sourced or sunk by the high-voltage battery 102 of the high-voltage system 10 of an electric vehicle V using:

[0064] (i) the current value lBatt_Raw measured in real time directly by the BMS control unit, if such a value is correctly available at that moment (which represents the preferred choice) - as exemplified in Figure 3; and

[0065] (ii) subordinate to point (i), the current value iBattjviodei estimated in real time by summing (with sign) the currents sourced or sunk by the other components of the high-voltage system 10 (in particular, summing the conventionally positive currents sunk by the loads such as the electric heater 106, the DC-DC converter 108 and the compressor 110, subtractingthe conventionally positive current sourced by the charger 104, and summing with sign the positive or negative current, sunk or sourced, by the inverters 112), if the current value lBatt_Raw measured in real time directly by the BMS control unit is not correctly available at that moment - as exemplified in Figure 4, and in the following Figures 5 to 27 which describe the methods for calculating the individual current contributions.

[0066] This basic idea is also exemplified in the block diagram of Figure 28, which illustrates a method 20 according to one or more embodiments for determining the value of the current (sourced or sunk) of the high-voltage battery 102 of the high-voltage system 10 of an electric vehicle V, comprising the following steps:

[0067] - in step 2802, the current Ichrg sourced by the charger 104 is calculated;

[0068] - in step 2804, the current IEAC sunk by the compressor 110 is calculated;

[0069] - in step 2806, the current IECH sunk by the electric heater 106 is calculated;

[0070] - in step 2808, the current / inverters sunk or sourced by the inverters 112 is calculated;

[0071] - in step 2810, the current IDCDC_HV sunk by the DC-DC converter 108 is calculated; and

[0072] - in step 2812, the current / Batt of the high-voltage battery (sourced or sunk) is calculated as a function of the previous ones.

[0073] Therefore, the method described herein allows determining the current sourced or sunk by the high-voltage battery 102 of the high-voltage system 10 even when, at a given instant, it is not possible to directly sense such a current via the BMS control unit, by estimating the currents sourced or sunk by the other components present in the high-voltage system 10. In this way, it is possible to use the functionalities of the vehicle V that require knowing the value of the current / Batt (i.e., substantially, all the functionalities that involve sinking current from the battery or sourcing current to the battery, which include primary functionalities such as vehicle charging and vehicle propulsion) even when a direct detection of the current / Batt is not possible, thereby increasing the usability of the vehicle and the perception of comfort and quality by the user, since all the most important functions ofthe vehicle (e.g., charging and propulsion) remain available (obviously, barring other more significant faults).

[0074] Of course, the details of implementation and the embodiments can be widely varied with respect to what has been described and illustrated without thereby departing from the scope of the invention as defined by the attached claims.

Claims

CLAIMS1. A method (20) of determining the battery current (iBatt) sourced or sunk by a high-voltage battery (102) of a high-voltage system (10) of an electric vehicle (V), wherein said high-voltage system (10) comprises said high-voltage battery (102), an on-board charger (104), an electric heater (106), a DC-DC converter (108), an electric compressor (110) and at least one inverter (112), the method (20) comprising:(i) receiving (302) from a management control unit of said battery (102) a first battery current value (lBatt_Raw) and a first binary signal (lBatt_Avi) indicative of whether said first battery current value (lBatt_Raw) is correctly available or not;(ii) in response to said first battery current value (lBatt_Raw) being correctly available, determining (302) that the battery current (IBatt) sourced or sunk by the high-voltage battery (102) is equal to said first battery current Value (I Batt_Raw)',(iii) in response to said first battery current value (lBatt_Raw) not being correctly available, calculating (202, 204, 206, 208, 210, 402) a second battery current value (iBattjviodei) based on a first partial current (Ichrg) sourced by said on-board charger (104), a second partial current (IEAC) sunk by said electric compressor (110), a third partial current (IECH) sunk by said electric heater (106), a fourth partial current (IDCDC_HV) sunk by said DC-DC converter (108), and a fifth partial current ( / inverters) sunk or sourced by said at least one inverter (112), and determining (302) that the battery current (iBatt) sourced or sunk by the high-voltage battery (102) is equal to said second battery current value (IBattjviodei).

2. A method (20) according to claim 1, wherein said first (Ichrg), second (IEAC), third (IECH) and fourth (IDCDC_HV) partial currents have a positive value, wherein said fifth partial current (hnverters) has a positive value if sunk by the at least one inverter (112) or a negative value if sourced by the at least one inverter (112), and wherein said second battery current value (iBattjviodei) is calculated by summing together the second (IEAC), third (IECH), fourth (IDCDC_HV) and fifth (hnverters) partial currents, and subtracting from this sum the first partial current (Ichrg).

3. A method (20) according to claim 1 or claim 2, comprisingdetermining (202) said first partial current (Ichrg) sourced by said on-board charger (104) by executing the following steps:- receiving (602) from the on-board charger (104) a measured value (lchrgconverter_Raw) of said first partial current Ichrg) measured by the on-board charger (104) and a second binary signal (lchrgconverter_Avi) indicative of whether said measured value (lchrgconverter_Raw) of the first partial current is correctly available or not;- in response to said measured value (lchrgconverter_Raw) of the first partial current being correctly available, determining (602) that the first partial current (Ichrg) is equal to said measured value (lchrgconverter_Raw) of the first partial current;- in response to said measured value (lchrgconverter_Raw) of the first partial current not being correctly available, computing (202, 702, 802, 902, 1002) an estimated value (Ichrgconverterjviodei) of said first partial current (Ichrg) based on a current (lchrgstation_Raw) sourced and measured by a charging infrastructure external to the vehicle (V), an output voltage ( Vchrgstation) sourced and measured by the charging infrastructure external to the vehicle (V), an efficiency (r / chrgconverter) of an electronic converter of said on-board charger (104), and an output voltage ( Vchrgconverter) sourced and measured by the electronic converter of said on-board charger (104), and determining (602) that the first partial current (Ichrg) is equal to said estimated value lchrgconverter_Modei) of the first partial current.

4. A method (20) according to claim 3, wherein said estimated value (lchrgconverter_Modei) of the first partial current is computed by multiplying said current (lchrgstation_Raw) sourced and measured by the charging infrastructure external to the vehicle (V), said output voltage ( Vchrgstation) sourced and measured by the charging infrastructure external to the vehicle (V), said efficiency (qchrgconverter) of the electronic converter of said on-board charger (104), and dividing such a product by said output voltage ( Vchrgconverter) sourced and measured by the electronic converter of said onboard charger (104).

5. A method (20) according to claim 3 or claim 4, comprising setting to zero said estimated value (lchrgconverter_Modei) of the first partial current if at least one among said current (lchrgstation_Raw) sourced and measured by the charging infrastructure external to the vehicle (V), saidoutput voltage ( Vchrgstation) sourced and measured by the charging infrastructure external to the vehicle (V), and said output voltage ( Vchrgconverter) sourced and measured by the electronic converter of said onboard charger (104) is not available.

6. A method (20) according to any of the preceding claims, comprising determining (204) said second partial current (IEAC) sunk by said electric compressor (110) by performing the following steps:- receiving (1102) from the electric compressor (110) a measured value (lEAc_Raw) of said second partial current (IEAC) measured by the electric compressor (110) and a third binary signal (IEAC_AVI) indicative of whether said measured value (lEAc_Raw) of the second partial current is correctly available or not;- in response to said measured value (lEAc_Raw) of the second partial current being correctly available, determining (1102) that the second partial current (IEAC) is equal to said measured value (lEAc_Raw) of the second partial current;- in response to said measured value (lEAc_Raw) of the second partial current not being correctly available, computing (204, 1102, 1202, 1302, 1402) an estimated value (lEAcjviodei) of said second partial current (IEAC) based on a voltage (VEAC) measured on the motor of said electric compressor (110), a pressure (PRef) of a refrigerant measured at the outlet of said electric compressor (110), and a rotational speed (IIEAC) of said electric compressor (110), and determining (1102) that the second partial current (IEAC) is equal to said estimated value (lEAcjviodei) of the second partial current.

7. A method (20) according to claim 6, wherein said estimated value (lEAc_Modei) of the second partial current is computed by dividing an electrical power (Q’EAC) sunk by said electric compressor (110), estimated as a function of said pressure (PRef) and of said rotational speed (IIEAC), by said voltage (VEAC) measured on the motor of said electric compressor (110).

8. A method (20) according to claim 6 or claim 7, comprising setting to zero said estimated value (lEAcjviodei) of the second partial current if at least one among said pressure (PRef), said rotational speed (IIEAC), and said voltage ( VEAC) measured on the motor of said electric compressor (110)is not available.

9. A method (20) according to any of the preceding claims, comprising determining (206) said third partial current (IECH) sunk by said electric heater (106) by performing the following steps:- receiving (1502) from the electric heater (106) a measured value (lECH_Raw) of said third partial current (IECH) measured by the electric heater (106) and a fourth binary signal (IECH_AVI) indicative of whether said measured value (lECH_Raw) of the third partial current is correctly available or not;- in response to said measured value (lECH_Raw) of the third partial current being correctly available, determining (1502) that the third partial current (IECH) is equal to said measured value (lECH_Raw) of the third partial current;- in response to said measured value (lECH_Raw) of the third partial current not being correctly available, determining (1502) that the third partial current (IECH) is equal to zero.

10. A method (20) according to any of the preceding claims, comprising determining (210) said fourth partial current (IDCDC_HV) sunk by said DC-DC converter (108) by performing the following steps:- receiving (1602) from the DC-DC converter (108) a measured value (lDCDc_Hv_Raw) of said fourth partial current (IDCDC_HV) measured by the DC-DC converter (108) and a fifth binary signal (IDCDC_HV_AVI) indicative of whether said measured value (IDCDC_HV_Raw) of the fourth partial current is correctly available or not;- in response to said measured value (IDCDC_HV_Raw) of the fourth partial current being correctly available, determining (1602) that the fourth partial current (IDCDC_HV) is equal to said measured value (lDCDc_Hv_Raw) of the fourth partial current;- in response to said measured value (IDCDC_HV_Raw) of the fourth partial current not being correctly available, computing (210, 1702, 1802, 1902, 2002) an estimated value (lDCDc_Hv_Modei) of said fourth partial current (IDCDC_HV) based on a current (IDCDC_LV_R3W) provided as output and measured by the DC-DC converter (108), a voltage ( VDCDC_LV) provided as output and measured by the DC-DC converter (108), an efficiency (r / DCDc) of the DC-DC converter (108) and a voltage ( VDCDC_HV) measured at theinput by the DC-DC converter (108), and determining (1602) that the fourth partial current (IDCDC_HV) is equal to said estimated value (lDCDc_Hv_Modei) of the fourth partial current.

11. A method (20) according to claim 10, wherein said estimated value (lDCDc_Hv_Modei) of the fourth partial current is computed by multiplying said current (lDCDc_Lv_Raw) provided as output and measured by the DC-DC converter (108) times said voltage ( VDCDC_LV) provided as output and measured by the DC-DC converter (108), and dividing such product by said efficiency (TIDCDC) of the DC-DC converter (108) and said voltage ( VDCDC_HV) measured at the input by the DC-DC converter (108).

12. A method (20) according to claim 10 or claim 11, comprising setting to zero said estimated value (lDCDc_Hv_Modei) of the fourth partial current if at least one among said current (lDCDc_Lv_Raw) provided as output and measured by the DC-DC converter (108), said voltage ( VDCDC_LV) provided as output and measured by the DC-DC converter (108), and said voltage ( VDCDC_HV) measured at the input by the DC-DC converter (108) is not available.

13. A method (20) according to any of the preceding claims, comprising determining (208) said fifth partial current ( / inverters) sunk or sourced by said at least one inverter (112) by executing the following steps:- receiving (2202) from the at least one inverter (112) a measured value (hnverter_i_Raw) of said fifth partial current ( / inverters) measured by the at least one inverter (112) and a sixth binary signal (I inverted _Avi) indicative of whether said measured value (I inverter j_Raw) of the fifth partial current is correctly available or not;- in response to said measured value (I inverter j_Raw) of the fifth partial current being correctly available, determining (2202) that the fifth partial current ( / inverters) is equal to said measured value (hnverters_i_Raw) of the fifth partial current;- in response to said measured value (hnvertersj_Raw) of the fifth partial current not being correctly available, computing (208, 2302, 2402, 2404, 2406, 2408, 2502, 2602, 2702) an estimated value (I inverter jjviodei) of said fifth partial current ( / inverters) based on an operating voltage ( Vinverterj) measured by the at least one inverter (112), a torque (Tiviotorj) delivered by the electric motor driven by the at least one inverter (112), a rotational speed (niviotorj)of the electric motor driven by the at least one inverter (112), an efficiency (r / inverter ) of the at least one inverter (112) and an efficiency (i Motorj) of the electric motor driven by the at least one inverter (112), and determining (2202) that the fifth partial current ( / inverters) is equal to said estimated value (I inverter_i_Modei) of the fifth partial current.

14. A method (20) according to claim 13, wherein said estimated value (I inverter_i_Modei) of the fifth partial current is computed:- by multiplying said torque (TMotorj) delivered by the electric motor times said rotational speed (riMotorj) of the electric motor, and dividing such product by said efficiency (i inverterj) of the at least one inverter (112) and said efficiency (i Motorj) of the electric motor, if the torque ( TMotorj) delivered by the electric motor and the rotational speed (riMotorj) of the electric motor have the same sign; or- by multiplying together said torque (TMotorj) delivered by the electric motor, said rotational speed (riMotorj) of the electric motor, said efficiency (r / inverterj) of the at least one inverter (112) and said efficiency (riMotorj) of the electric motor, if the torque ( TMotorj) delivered by the electric motor and the rotational speed (riMotorj) of the electric motor have different signs.

15. A method (20) according to claim 13 or claim 14, comprising setting to zero said estimated value (I inverter jjviodei) of the fifth partial current if at least one among said operating voltage ( Vinverterj) measured by the at least one inverter (112), said torque (TMotorj) delivered by the electric motor driven by the at least one inverter (112), and said rotational speed (riMotorj) of the electric motor driven by the at least one inverter (112) is not available.

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