Method for controlling a DC-DC converter in a vehicle having an electric traction motor and corresponding vehicle

Abstract

A method for controlling a DC-DC converter comprised in a vehicle having an electric traction motor, said vehicle comprising a first battery having a first supply voltage, and a second battery having a second supply voltage, said second supply voltage being higher than the first supply voltage, wherein said DC-DC converter is configured to transfer energy from said second battery to said first battery; said method comprising: limiting (210) a current to be drawn, via the DC-DC converter, from the second battery as a function of an electrical power (EDCDC_Lim)) absorbable from said second battery, obtaining a limited current to be drawn (iDCDC_HV_Lim); determining (206) a current to be supplied, (iBatt_LV_Tgt), via the DC-DC converter, to said first battery as a function of a difference between a state of charge to be reached by the first battery (SOCBatt_LV_Tgt) and a current state of charge (SOCBatt_LV) of the first battery; and determining (208) a voltage to be applied (VDCDC_LV_Tgt), via the DC-DC converter, to said first battery as a function of the current state of charge (SOCBatt_LV) of the first battery, of a current being currently supplied (iBatt_LV) to the first battery and of the determined current to be supplied (iBatt_LV_Tgt).

Description

[0001] "Method for controlling a DC-DC converter in a vehicle having an electric traction motor and corresponding vehicle"

[0002] ★ ★ ★ ★

[0003] TEXT OF THE DESCRIPTION

[0004] Field of the Invention

[0005] The embodiments of the present description refer to methods for controlling a DC-DC ("Direct Current-to- Direct Current" ) converter in vehicles having electric traction motors .

[0006] In particular , various embodiments of the present description regard solutions for controlling a DC-DC converter configured to trans fer energy from at least one high-voltage battery to at least one low-voltage battery, such at least one low-voltage battery and such at least one high-voltage battery being comprised in vehicles having electric traction motors .

[0007] Known Art

[0008] The vehicles having electric traction motors are provided with electric systems comprising a low-voltage electric system, powered by one or more low-voltage batteries , and a high-voltage electric system, powered by one or more high-voltage batteries , which systems are di f ferent as regards the use and the voltage level thereof .

[0009] Such vehicles having electric traction motors usually comprise DC-DC ("Direct Current-Direct Current" ) converters for trans ferring energy from a high-voltage battery ( coupled to the DC-DC converter via a high- voltage side of such DC-DC converter ) , typically used to power the propulsion of such vehicles , to a low-voltage battery ( coupled to the DC-DC converter via a low-voltage side of such DC-DC converter ) , used to power auxiliary electric systems such as lamps , windscreen wipers , infotainment systems and the like . Known solutions do not allow controlling a supply provided to a low-voltage battery separately from a supply provided to the auxiliary components , for example , the auxiliary electric systems described in the foregoing .

[0010] Therefore , solutions for favouring a separate control of the supply provided to the low-voltage battery with respect to the supply provided to the auxiliary components would be advantageous .

[0011] Obj ect of the Invention

[0012] The invention aims at solving the technical problems mentioned in the foregoing . Speci fically, the invention aims at providing a method for control ling a DC-DC converter in a vehicle having an electric traction motor, by attempting to favour a separate control of the supply provided to the low-voltage battery with respect to the supply provided to the auxiliary components .

[0013] Summary of the Invention

[0014] The obj ect of the invention is achieved by means of a method having the features set forth in the claims that follow, which are an integral part of the technical teaching provided herein in relation to the invention .

[0015] One or more embodiments refer to a corresponding vehicle .

[0016] Brief Description of the Figures

[0017] One or more embodiments will now be described, by way of example only, with reference to the annexed Figures , wherein :

[0018] Figure 1 shows an exemplary current exchange between a DC-DC converter, a low-voltage battery, and auxiliary components , according to embodiments of the present description;

[0019] Figure 2 shows a block diagram related to a control strategy of a DC-DC converter according to embodiments of the present description; - Figure 3 shows a block for defining a target state of charge of a low-voltage battery according to embodiments of the present description;

[0020] Figure 4 shows a block for calculating, for instance , via a map, an ef ficiency of the DC-DC converter according to embodiments of the present description;

[0021] - Figure 5 shows a block for defining a minimum voltage value related to a low-voltage side of the DC- DC converter according to embodiments of the present description;

[0022] - Figure 6 shows a block for defining, for instance , via a map, a maximum voltage value related to the low- voltage side of the DC-DC converter according to embodiments of the present description;

[0023] - Figure 7 shows a block for defining a target current of a low-voltage battery according to embodiments of the present description;

[0024] - Figure 8 shows a block for defining a target voltage related to the low-voltage side of the DC-DC converter according to embodiments of the present description; and

[0025] - Figure 9 shows a flow chart of an exemplary method for controlling a DC-DC converter in a vehicle having an electric traction motor, according to embodiments o f the present description .

[0026] Detailed Description

[0027] In the following description one or more speci fic details are illustrated in order to provide a thorough understanding of exemplary embodiments of the present disclosure . The embodiments may be practiced without one or more of the speci fic details or with other methods , components , materials , etc . In other instances , known operations , materials or structures are not illustrated or described in detail in order not to obscure certain aspects of the embodiments . A reference to "an embodiment" or "one embodiment" in the present description is meant to indicate that a particular configuration, structure or feature described with reference to the embodiment is comprised in at least one embodiment . Therefore, phrases such as " in an embodiment" or " in one embodiment" or the like , which may be present in one or more parts of the present description, do not necessarily refer to one and the same embodiment .

[0028] Moreover, particular configurations , structures or features may be combined in any suitable way in one or more embodiments .

[0029] The headings used herein are provided for convenience only, and thus they do not limit the extent of protection or the scope of the embodiments .

[0030] Throughout the Figures annexed herein and throughout the detailed description that follows , unless the context dictates otherwise , the similar parts or elements are denoted with similar references / numbers , and a corresponding description wi ll not be repeated for the sake of brevity .

[0031] As mentioned in the foregoing, solutions as described herein aim at favouring a separate control of the supply provided to the low-voltage battery with respect to the supply provided to auxiliary components .

[0032] Solutions as described herein may allow to dynamically manage , for example , by increasing or decreasing, the electrical power drawn by the low- voltage battery so as to facilitate reaching given performances related to the auxiliary components .

[0033] For example , solutions as described herein may allow to reduce the electrical power drawn by the low- voltage battery during the acceleration of the vehicle without af fecting the auxiliary components , in such a way as to save power which may be used for the propulsion of the vehicle .

[0034] Embodiments according to the present description may be applied to vehicles having electric traction motors comprising at least one low-voltage electric system, supplied by at least one low-voltage battery, and at least one high-voltage electric system, supplied by at least one high-voltage battery .

[0035] Such vehicles having electric traction motors further comprise DC-DC ("Direct Current-Direct Current" ) converters for trans ferring energy from the at least one high-voltage battery ( coupled with the DC-DC converter via a high-voltage side of such DC-DC converter ) , for example , a battery characteri zed by a supply voltage of about 800 V (volts ) , to the at least one low-voltage battery ( coupled with the DC-DC converter via a low- voltage side of such DC-DC converter ) , for example , a battery characteri zed by a supply voltage of about 12 V (volts ) .

[0036] Embodiments of methods for controlling DC-DC converters according to the present description allow to dynamically manage the supply voltage provided to a low- voltage battery and to the auxiliary components , by controlling the maximum power drawn from the high- voltage side of such DC-DC converters , for example , by controlling a current drawn from the high-voltage battery, and the maximum power drawn by the low-voltage battery, for example by controlling a voltage applied to such low-voltage battery .

[0037] It is noted that the supply provided to the low- voltage battery may be controlled by modi fying such maximum power drawn by the low-voltage battery, that is , by modi fying the voltage applied to such low-voltage battery, thus , separating the control of the supply of the low-voltage battery with respect to the auxiliary components comprised in the vehicle . Instead, for example , the supply provided to the low-voltage electric system, that is , comprising both the low-voltage battery and the auxiliary components , may be controlled by modi fying such maximum power drawn from the high-voltage side of the DC-DC converter, that is , by modi fying the current drawn from the high-voltage battery .

[0038] Therefore , embodiments according to the present description refer to a method for controlling a DC-DC converter, for example , the DC-DC converter 100 shown in Figure 1 , comprised in a vehicle having an electric traction motor, such vehicle comprising :

[0039] - a first battery, that is , a low-voltage battery, for example , the low-voltage battery 104 shown in Figure 1 , having a first supply voltage , for example , a supply voltage of 12 volts , and

[0040] - a second battery, that is , a high-voltage battery, having a second supply voltage , such second supply voltage being higher than the first supply voltage , for example , a supply voltage of 800 volts , wherein such DC-DC converter 100 is configured to trans fer energy from such second battery to such first battery 104 .

[0041] According to embodiments of the present description, such method comprises :

[0042] - limiting, for example , via a block 210 described in the following and shown in Figure 2 , a current to be drawn, via the DC-DC converter 100 , from the second battery, that is , from the high-voltage battery, as a function of an electrical power absorbable from such second battery ( or, for example , of a maximum electrical power stored in such high-voltage battery or of a part of such maximum electrical power) , obtaining a limited current to be drawn from the high-voltage battery; determining, for example , via a block 206 described in the following and shown in Figure 2 , a current to be supplied ( for example , the current isatt_Lv described in the following and shown in Figure 1 ) , via the DC-DC converter 100 , to such first battery 104 , that is , to the low-voltage battery, as a function of a di f ference between a state of charge to be reached by the first battery and a current state of charge of such first battery 104 ; and determining, for example , via a block 208 described in the following and shown in Figure 2 , a voltage to be applied, via the DC-DC converter 100 , to such first battery 104 , that is , to the low-voltage battery, as a function of the current state of charge of the first battery 104 , a current that is currently supplied to the first battery 104 , and the current to be supplied determined in the previous step .

[0043] In addition, in embodiments of methods for controlling DC-DC converters according to the present description, it is possible to dynamically manage the charging and discharging operations of a low-voltage battery .

[0044] It is also noted that embodiments of methods for controlling DC-DC converters according to the present description may allow to reduce the overall energy losses related to a considered vehicle having an electric traction motor and, simultaneously, increasing the useful li fe of a low-voltage battery comprised in such considered vehicle .

[0045] Therefore , a method for controlling DC-DC converters according to embodiments of the present description allows to control separately the supply of the low-voltage battery comprised in the vehicle with respect to auxiliary components , such as , for instance , pumps , fans , blowers , lamps , and the like .

[0046] It is noted that , even though the low-voltage battery is characteri zed by a given supply voltage , for example a supply voltage of 12 V, the method for controlling DC-DC converters according to embodiments of the present description may also be implemented in the presence of low-voltage batteries characteri zed by supply voltages other than such given supply voltage, for example , with supply voltages other than 12 V .

[0047] Figure 1 shows 10 an exemplary current exchange 102 between a DC-DC converter 100 , a low-voltage battery 104 , and low-voltage auxiliary components 106 according to embodiments of the present description .

[0048] It is noted that such low-voltage auxiliary components 106 are only consumers of electric power, whereas such low-voltage battery 104 is able to both supply and absorb electric power, that is , it is a bidirectional component .

[0049] It is also noted that both the low-voltage battery and the auxiliary components may be comprised in the low-voltage electric system, such low-voltage battery being a passive component of the low-voltage electric system, and such auxiliary components , for example , lamps , radios , or the like , being active energy absorbers .

[0050] The DC-DC converter 100 shown in Figure 1 is configured to receive , at a high-voltage side of such DC-DC converter 100 , a high-voltage supply current 1DCDC_HV drawn from such high-voltage side , that is , from the high-voltage battery comprised in the high-voltage electric system of a considered vehicle ( that is , it is configured to draw energy from such high-voltage side ) .

[0051] Such DC-DC converter 100 is further configured to supply to a node 102 , via a low-voltage side of such DC- DC converter 100 , a low-voltage output current 1DCDC_LV ( that is , it is configured to supply energy to such low- voltage side ) . Such node 102 is coupled with such low-voltage battery 104 and to such auxiliary components 106 , and it is configured to provide a first component of the received current , that is , a component of the low-voltage battery isatt_Lv, to the low-voltage battery 104 , and a second component of the received current , that is , a component of the low-voltage auxiliary components 1AUX_LV, to the low-voltage auxiliary components 106 .

[0052] The current which is exchanged, via the node 102 , between the DC-DC converter 100 , the low-voltage battery 104 , and the low-voltage auxiliary components 106 may be expressed via the following equation : lAux_LV= lDCDC_LV ~lBatt_LV

[0053] It is noted that the term related to the component of the low-voltage battery isatt_Lv is considered as positive when the current enters in the low-voltage battery .

[0054] Therefore , by managing the DC-DC converter 100 it is possible to control :

[0055] - the current flow for charging and discharging the low-voltage battery, for example , having a supply voltage of 12 volts , that is , such component of the low- voltage battery isatt_Lv, and the current flow traversing the high-voltage electric system, that is , from the high-voltage battery to the low-voltage electric system, that is , both to the low-voltage battery and to the auxiliary components , that is , the output low- voltage current 1DCDC_LV .

[0056] It is noted that via such management of the DC-DC converter 100 it is not possible to control the current flow provided to the auxiliary components ( that is , to the auxiliary absorbers ) , that is , the component of the low-voltage auxi liary components 1AUX_LV, since such auxiliary components are controlled by other systems , for example by one or more control units of the vehicle configured to manage one or more such auxiliary components .

[0057] For example , such DC-DC converter 100 may be controlled via control requests related to :

[0058] - a target voltage that has to be met on the low- voltage side of the DC-DC converter ; and

[0059] - a maximum input current , absorbable by the high- voltage side of the DC-DC converter .

[0060] It is noted that , out of such control requests of the DC-DC converter 100 , those that have a priority are usually the requests related to the maximum input current absorbable by the high-voltage side of the DC-DC converter, that is , the requests related to a limit of the current absorbable by the high-voltage side , with respect to the requests related to the target voltage which has to be met on the low-voltage side of the DC- DC converter, that is , to a voltage target of the low- voltage side .

[0061] Therefore , i f the maximum input current of the DC- DC converter is limited, such DC-DC converter may not be able to guarantee also the requested target voltage which has to be met on the low-voltage side of the DC-DC converter .

[0062] For example , i f , through such l imitation of the maximum input current of the DC-DC converter, the current flow from the high-voltage side to the low-voltage side of the DC-Dc converter is interrupted, then the auxiliary components , being controlled by other systems , would continue to absorb energy from the low-voltage battery .

[0063] In fact , in such a case , such other systems would have to be configured to limit the current absorbed by the respective auxiliary components .

[0064] Such requests related to the target voltage which has to be met on the low-voltage side of the DC-DC converter 100 may be managed as a function of the vehicle conditions , that is , by dynamically adj usting the charge and the discharge of the low-voltage battery of the vehicle to the current driving conditions , while the request related to the maximum input current absorbable by the high-voltage side of the DC-DC converter is kept constant , for example , at a maximum value , in such a way as to be able to adj ust the current flow during charging and discharging in the low-voltage battery .

[0065] Therefore , i f the maximum input current of the DC- DC converter is limited, it is possible to lose the control , as described in the foregoing, of the target voltage on the low-voltage side of the DC-DC converter .

[0066] As a consequence , such limitation of the maximum input current of the DC-DC converter may be implemented in critical energy conditions , for example , when the energy stored in the high-voltage battery is nearly depleted and a further discharge would lead to its damaging .

[0067] In this case , i f the auxiliary components , that is , the absorbers , are not limited by the respective other control systems , such auxiliary components will be able to continue to absorb power from the low-voltage battery until such low-voltage battery is completely depleted, thus avoiding damaging the high-voltage battery .

[0068] Figure 2 shows a block diagram 20 related to a control strategy of a DC-DC converter 100 according to embodiments of the present disclosure .

[0069] Such Figure comprises a definition block 200 of a target state of charge of the low-voltage battery .

[0070] An exemplary definition block 200 of the target state of charge of the low-voltage battery according to embodiments of the present description is shown in Figure 3 .

[0071] Such definition block 200 of the target state of charge of the low-voltage battery may be configured to receive : a driving mode Drv_Mod indicating a current driving mode ; and a full charge request Full_Chrg_Req of the battery, indicating to charge the low-voltage battery either completely, that is , until reaching a maximum state of charge which can be reached by such low-voltage battery, or partially, that is , until reaching a target state of charge related to a current driving mode .

[0072] Such definition block 200 of the target state of charge of the low-voltage battery may be further configured to provide as output , based on such driving mode Drv_Mod and / or based on such full charge request Full_Chrg_Req of the battery, a target state of charge of the low- voltage battery SOCBatt_Lv_ gt .

[0073] As shown in Figure 3 , such target state of charge of the low-voltage battery SOCBatt_Lv_ gt may be provided as output through a selection unit 200a.

[0074] Such selection unit 200amay be configured to receive : through a first input terminal , such maximum state of charge SOC gt_HVBatchrg that can be reached by such low-voltage battery; through a second input terminal , such target state of charge SOC gt_DrvMod related to a current driving mode ; and

[0075] - through a selection terminal , such full charge request of the battery Full_Chrg_Req .

[0076] I f such full charge request of the battery Full_Chrg_Req indicates to charge the low-voltage battery completely ( for example , i f such full charge request of the battery Full_Chrg_Req is a binary variable related to a high logic level ) , such selection unit 200amay be configured to couple the first input terminal to an output terminal , that is , to a terminal configured to provide as output such target state of charge of the low- voltage battery SOCBatt_Lv_ gt .

[0077] Therefore , a target state of charge of the low- voltage battery SOCBatt_Lv_ gt equal to such maximum state of charge that can be reached by such low-voltage battery SOCTgt_HVBatchrg is provided as output .

[0078] For example , such full charge request may be made in response to a full charge request of the high-voltage battery, for example , during a recharging period of a considered vehicle having an electric traction motor .

[0079] In this way, it is possible to store a maximum amount of electrical power within the considered vehicle before starting driving and, speci fically, within such low-voltage battery .

[0080] Hence , a driving range of such considered vehicle may be increased since such low-voltage battery has not to be charged by the high-voltage battery during driving, in fact , both such low-voltage battery and such high- voltage battery are charged up to respective maximum states of charge, thereby storing the maximum possible amount of electrical power within the vehicle .

[0081] Alternatively, i f such full charge request Full_Chrg_Req of the battery indicates to charge the low-voltage battery partially, that is , to charge the low-voltage battery as a function of a current driving mode ( for example , i f such full charge request Full_Chrg_Req of the battery is a binary variable related to a low logic level ) , such selection unit 200amay be configured to couple the second input terminal to such output terminal .

[0082] Therefore , a target state of charge of the low- voltage battery SOCBatt_Lv_ gt equal to such target state of charge related to the current driving mode SOC gt_DrvMod is provided as output .

[0083] For example , such request of partial charge may be made while driving, for example , while the considered vehicle is in motion .

[0084] It is noted that such target state of charge related to the current driving mode SOC gt_DrvMod may be extrapolated from a map, for instance , the map 200b, as a function of the received driving mode Drv_Mod, that is , of a current driving mode .

[0085] Such map 200b, for example , stored in a memory of an electronic control unit of the vehicle , may express values of target state of charge related to respective driving modes SOC gt_DrvMod as a function of such respective driving modes Drv_Mod available in the considered vehicle .

[0086] It is noted that such map 200b may contain values of target state of charge to be used in high-performance driving conditions which are higher than the values to be used in lower-performance driving conditions .

[0087] In fact , higher values of state of charge of the low-voltage battery allow to use such low-voltage battery for powering the auxiliary components during short periods of acceleration, instead of using the high- voltage battery .

[0088] In this way it is possible to employ for the propulsion of the vehicle a higher percentage o f the power that can be generated by the high-voltage battery .

[0089] Therefore , a method according to the present description may comprise an operation of determining, for example , performed via such definition block 200 , such state of charge to be reached, that is , the target state of charge SOCBatt_Lv_ gt, by the first battery, that is , by the low-voltage battery 104 .

[0090] For example , such operation of determining may take place , i f a charging indication of the second battery indicates that such second battery is in a charging state , for example , i f the full charge request of the battery Full_Chrg_Req has a high logic level , equalling such state of charge to be reached SOCBatt_Lv_Tgt to a maximum state of charge reachable by such first battery, for example , the maximum state of charge that can be reached by such low- voltage battery SOCTgt_HVBatchrg .

[0091] Alternatively, such determination operation may take place as a function of a driving mode Drv_Mod of such vehicle , preferably via extrapolation from a map, for instance , the map 200b, that expresses states of charge to be reached SOCBatt_Lv_Tgt of the first battery 104 as a function of driving modes Drv_Mod .

[0092] The block diagram 20 of Figure 2 shows a definition block 202 of a limit current of the low-voltage battery .

[0093] Such definition block 202 of the limit current of the low-voltage battery may be configured to receive :

[0094] - a maximum value of electrical power EBatt LV Limrelated to a supply of the low-voltage battery and indicating a budget of limit electrical power which may be currently used;

[0095] - a voltage VDCDC_LV of the low-voltage side of the converter DC-DC 100 ; and

[0096] - a current 1DCDC_LV of the low-voltage side of the DC-DC converter 100 .

[0097] Such definition block 202 of the limit current of the low-voltage battery may be further configured to provide as output a limit current iBatt_Lv_Lim of the low- voltage battery, that is , a maximum value of current supplied to the low-voltage battery isatt_Lv, which is obtained as a function of such limit value of electrical power EBat Lyjjjn .

[0098] For example , such limit current iBatt_Lv_Lim of the low-voltage battery may be obtained via the following equation : wherein Y]DCDC isaconversion ef ficiency from the high- voltage side to the low-voltage side of the DC-DC converter .

[0099] Such conversion ef ficiency IJDCDC may be , for example , extrapolated from a map, for instance , the map shown in Figure 4 .

[0100] Such Figure 4 shows a calculation block 30 , for example , via a map 300 , of a conversion ef ficiency r / DCDCof the DC-DC converter according to embodiments of the present description .

[0101] Such calculation block 30 may be configured to receive :

[0102] - the present voltage VDCDC_LV of the low-voltage side of the DC-DC converter 100 , for example , a first voltage value VDCDC_LV1 , a second voltage value VDCDC_LV2 , a third voltage value VDCDC_LV3 , a fourth voltage value VDCDC_LV4 , or other voltage values VDCDC_LV; and

[0103] - the present current 1DCDC_LV of the low-voltage side of the DC-DC converter 100 .

[0104] Such calculation block 30 may further be configured to provide as output a conversion ef ficiency IJDCDC based on such present voltage VDCDC_LV of the low-voltage side of the DC-DC converter 100 and on such present current 1DCDC_LV of the low-voltage side o f the DC-DC converter 100 .

[0105] For example , i f the relationship between such conversion ef ficiency r / DCDCand such present voltage and current VDCDC_LV and 1DCDC_LV of the low-voltage side of the DC-DC converter 100 is expressed via a map, for example , the map 300 of Figure 4 , such calculation block 30 may be configured for extrapolating from such map 300 such conversion ef ficiency r / DCDCas a function of the received present voltage VDCDC_LV and current 1DCDC_LV of the low- voltage side of the DC-DC converter 100 .

[0106] In fact , such map 300 , for example , stored in a memory of an electronic control unit of the vehicle , may express values of conversion ef ficiency T)DCDCas a function of values of voltages VDCDC_LV and currents 1DCDC_LV related to the low-voltage side of the DC-DC converter 100 .

[0107] For example , such voltage VDCDC_LV of the low-voltage side of the DC-DC converter 100 may be measured by the DC-DC converter itsel f .

[0108] Therefore , a method according to the present description may comprise an operation of determining, for example , performed via such definition block 202 , a current limit , that is , the limit current iBatt_Lv_Lim of the low-voltage battery .

[0109] Such current limit is obtained by dividing an electrical power stored in such first battery 104 , that is , a maximum value of electrical power EBatt LV Limrelated to a supply of the low-voltage battery, by a voltage currently being output from the DC-DC converter VDCDC_LV to the first battery 104 , that i s , a voltage currently being applied on the low-voltage side of the DC-DC converter VDCDC_LV, possibly, by multiplying the result of such division operation by a conversion ef ficiency r / DCDCof the DC-DC converter 100 .

[0110] The block diagram 20 of Figure 2 shows even a definition block 204 of limit voltages of the low-voltage side of the DC-DC converter 100 .

[0111] Such definition block 204 of limit voltages of the low-voltage side of the DC-DC converter 100 may be configured to receive : a defrost activation request Def rost_Act_Req which indicates to activate or deactivate a defrost function, i f present ;

[0112] - a target speed of components Comp_Spd_Tgt which require a minimum supply voltage to maintain such target speed, i f they are present ; - a current state of charge of the low-voltage battery S OCBatt_Lv ,- and

[0113] - a current temperature of the low-voltage battery TBatt_LV •

[0114] Such definition block 204 of limit voltages of the low-voltage side of the DC-DC converter 100 may be further configured to provide as output , based on such received information : a first limit related to a minimum voltage VDcDc_Lv_Min of the low-voltage side of the converter DC-DC 100 , such minimum voltage VDcDc_Lv_Min being defined to supply the actuators in such a way as to obtain requested performances and to prevent an early aging of the low- voltage battery; and a second limit related to a maximum voltage VocDc_Lv_Max of the low-voltage side of the DC-DC converter 100 , such maximum voltage VDcDc_Lv_Max being defined to prevent gasi fication problems of the low-voltage battery .

[0115] For example , such definition block 204 of limit voltages of the low-voltage side of the DC-DC converter 100 may comprise a first definition block, for example , the definition block 40 shown in Figure 5 , configured to define such minimum voltage VDcDc_Lv_Min of the low-voltage side of the DC-DC converter 100 and a second definition block, for example , the definition block 50 shown in Figure 6 , configured to define such maximum voltage VocDc_Lv_Max of the low-voltage side of the DC-DC converter 100 .

[0116] Figure 5 , as described in the foregoing, shows a definition block 40 configured to define a first limit related to a minimum voltage VDcDc_Lv_Min of the low-voltage side of the DC-DC converter 100 , according to embodiments of the present description .

[0117] It is noted that , although the following description and the illustration of Figure 5 consider, as components requiring a minimum supply voltage to maintain a target speed, four pumps , a fan and a blower, any other component may be considered : for example , additional components may be present which require a minimum supply voltage to maintain a target speed or some of the described components may not be present .

[0118] The minimum voltage VDcDc_Lv_Min of the low-voltage side of the DC-DC converter 100 may be obtained via a maximi zing operation, for example , performed by a first maximi zation block 400 , as a maximum out of :

[0119] - the minimum supply voltages required to maintain target speeds in respective components , i f such components are present ;

[0120] - a minimum supply voltage to reduce the aging of the low-voltage battery Vage_Min; and

[0121] - a minimum voltage required for defrost functions VDef rost_Min , i f such defrost functions are present .

[0122] In the exemplary situation of Figure 5 , that is , in a situation wherein such components requiring a minimum supply voltage to maintain a target speed comprise four pumps , a fan and a blower, such minimum supply voltages required to maintain target speeds in respective components comprise :

[0123] - a maximum supply voltage VpUmP_Min out of minimum supply voltages required to maintain target speeds in the four pumps , such minimum supply voltages allowing, for example , the achievement of the required performances in such four pumps ; a minimum supply voltage VFAN_Min required to maintain a target speed in the fan which, for example , allows the achievement of the required performance in such fan; and

[0124] - a minimum supply voltage VBiower_Min required to maintain a target speed in the blower, which, for example , allows the achievement of the required performances in such blower .

[0125] For example, such required minimum supply voltages may be extrapolated from maps based on respective target speeds to be maintained, such maps being configured to express required minimum supply voltages as a function of target speeds .

[0126] For example, in embodiments according to Figure 5, such maximum supply voltage Vpump_MiR out of the minimum supply voltages required to maintain target speeds in the four pumps may be obtained : by selecting, for example , via a second maximi zation block 404 , a maximum target speed Pump_Spd_TgtMax out of the target speeds of the four pumps , that is , out of a first target speed Pumpl_Spd_Tgt , a second target speed Pump2_Spd_Tgt , a third target speed Pump3_Spd_Tgt and a fourth target speed Pump4_Spd_Tgt ; and

[0127] - by extrapolating, for example , from a map 402 configured to express maximum supply voltages Vpump_Min out of minimum supply voltages required to maintain target speeds in the four pumps as a function of target speeds Pump_Spd of the four pumps , such maximum supply voltage VPump_Min as a function of such selected maximum target speed Pump_Spd_TgtMax .

[0128] It is noted that such extrapolated maximum supply voltage Vpump_Min may be provided as input to the first maximi zation block 400 .

[0129] For example, in embodiments according to Figure 5, such minimum supply voltage VFAN_MIR required to maintain a target speed in the fan FAN_Spd_Tgt may be obtained by extrapolating, for example , from a map 406 configured to express minimum supply voltages VFAN_MIR required to maintain a target speed in the fan as a function of the target speeds FAN_Spd of the fan, based on such target speed of the fan FAN_Spd_Tgt .

[0130] It is noted that such minimum supply voltage VFAN_MIR required to maintain a target speed in the fan may be provided as input to the first maximi zation block 400 .

[0131] For example, in embodiments according to Figure 5, such minimum supply voltage VBiOwer_Min required to maintain a target speed in the blower CabinBlower_Spd_Tgt may be obtained by extrapolation, for example , from a map 408 configured to express minimum supply voltages VBiower_Min required to maintain a target speed in the blower as a function of target speeds Blower_Spd of the blower, based on such target speed of the blower CabinBlower_Spd_Tgt .

[0132] It is noted that such minimum supply voltage VBiower_Min required to maintain a target speed in the blower may be provided as input to the first maximi zation block 400 .

[0133] The minimum supply voltage to reduce the aging of the low-voltage battery Vage_Min may be extrapolated, for example , from a map 410 , based on the current state of charge of the low-voltage battery SOCBatt_Lv and on the current temperature of the low-voltage battery TBatt_Lv.

[0134] Therefore , such map 410 may express values of minimum supply voltage to reduce the aging of the low- voltage battery Vage_Min as a function of states of charge of the low-voltage battery SOCBatt_Lv and of temperatures of the low-voltage battery TBatt_Lv.

[0135] Figure 6 , as described in the foregoing, shows a definition block 50 configured to define , for example , via a map 500 , a second limit related to a maximum voltage VBcDc_Lv_Max of the low-voltage side of the DC-DC converter 100 according to embodiments of the present disclosure .

[0136] Such definition block 50 may be configured to receive the current temperature of the low-voltage battery TBatt_Lv and to provide as output a maximum voltage VDcDc_Lv_Max of the low-voltage side of the DC-DC converter 100 based on such received current temperature of the low-voltage battery TBatt_Lv.

[0137] For example , i f the relationship between such maximum voltage VDCDC_LV_MSX of the low-voltage side of the DC-DC converter 100 and the current temperature of the low-voltage battery TBatt_Lv is expressed using a map, for example , the map 500 of Figure 6 , such definition block 50 may be configured to extrapolate from such map 500 such maximum voltage VBcDc_Lv_Max as a function of the received current temperature of the low-voltage battery TBatt_LV •

[0138] In fact , such map 500 , for example , stored in a memory of an electronic control unit of the vehicle , may express values of maximum voltage VBcDc_Lv_Max as a function of temperature values of the low-voltage battery TBatt_Lv, that is , may be configured to contain a gasi fication curve of the low-voltage battery .

[0139] Therefore , such maximum voltage VBcDc_Lv_Max may be extrapolated from the gasi fication curve of the low- voltage battery based on such current temperature o f the low-voltage battery TBatt_Lv measured, for instance , via an internal sensor of the low-voltage battery .

[0140] Therefore , a method according to the present description may comprise an operation of determining, for example , performed in the block 204 :

[0141] - a first voltage limit , for example , such maximum voltage VBcDc_Lv_Max, as a function of a temperature TBatt_Lv of the first battery 104 ; and / or

[0142] - a second voltage limit , for example , such minimum voltage VBcDc_Lv_Min, as a function of such temperature TBatt_Lv of the first battery 104 , such current state of charge SOCBatt_Lv of the first battery 104 , preferably, an indication of activation of a defrost function of the vehicle , for example , via the defrost activation request Def rost_Act_Req, i f such defrost function is present , and preferably, a given speed of components ( Comp_Spd_Tgt ) of the vehicle operating at such given speed, i f such components are present in the vehicle .

[0143] The block diagram 20 of Figure 2 shows a definition block 206 of a target current of a low-voltage battery .

[0144] Such definition block 206 of the target current of the low-voltage battery may be configured to receive :

[0145] - the target state of charge of the low-voltage battery SOCBatt_Lv_ gt from the definition block 200 of the target state of charge of the low-voltage battery;

[0146] - the limit current iBatt_Lv_Lim o f the low-voltage battery, that is , the maximum value of the current supplied to the low-voltage battery isatt_Lv, from the definition block 202 of the limit current of the low- voltage battery;

[0147] - a fast charge request of the low-voltage battery LV_Batt_Fst_Chrg_Req; and

[0148] - the state of charge of the low-voltage battery SOCsatt_Lv, that is , a current state of charge of the low- voltage battery .

[0149] Such definition block 206 of the target current of the low-voltage battery may be further configured to provide as output a target current isatt_Lv_ gt of the low- voltage battery, that is , a target current supplied ( that is , provided as input ) to the low-voltage battery, based on such received information, such target current isatt_Lv_ gt being such as to enable reaching the target state of charge SOCBatt_Lv_ gt with a required dynamics and, preferably, without exceeding the limit current isatt_LV_Lim •

[0150] Figure 7 shows such definition block 206 of the target current of the low-voltage battery according to embodiments of the present description .

[0151] Such target current isatt_Lv_ gt of the low-voltage battery may be obtained via a minimi zation operation, for example , performed by a minimi zation block 206a, as the minimum value out of the limit current iBatt_Lv_Lim of the low-voltage battery and a selected current isei, thereby limiting the selected current iseito the value of the limit current iBatt_Lv_Lim i f such selected current i sei is greater than the value of the limit current l Batt_LV_Lim •

[0152] The selected current iseimay be selected, for example , via a selection block 206b, based on the value of the received fast charge request of the low-voltage battery LV_Batt_Fst_Chrg_Req .

[0153] I f the fast charge request of the low-voltage battery LV_Batt_Fst_Chrg_Req indicates to fast recharge such low-voltage battery, for example , i f such fast charge request LV_Batt_Fst_Chrg_Req is a binary variable related to a high logic level , the selector block 206 may be configured to select as the selected current iseia target current related to a fast charge of the low- voltage battery iBatt_Lv_ gt_Fst, that is , a current that allows to recharge the low-voltage battery in the fastest way related to a fast charge mode of the vehicle .

[0154] Otherwise , i f the fast charge request of the low- voltage battery LV_Batt_Fst_Chrg_Req indicates not to fast recharge such low-voltage battery, for example , i f such fast charge request LV_Batt_Fst_Chrg_Req is a binary variable related to a low logic level , the selector block 206b may be configured to select as the selected current iseia raw target current supplied to the low- voltage battery i Batt_Lv_Tgt_Raw .

[0155] Such raw target current supplied to the low-voltage battery iBatt_Lv_Tgt_Raw may be extrapolated, for example , from a map 206c, as a function of a di f ference of state of charge ASOC .

[0156] Such di f ference of state of charge ASOC may be obtained via a subtraction operation, for instance , performed via a subtraction block 206d of states of charge , between the target state of charge of the low- voltage battery SOCBatt_Lv_Tgt received from the definition block 200 of the target state of charge of the low- voltage battery and the current state of charge of the low-voltage battery SOCBatt_Lv.

[0157] Such map 206c, for example , stored in a memory o f an electronic control unit of the vehicle , may express values of raw target currents isatt_Lv_Tgt_Raw as a function of values of di f ferences of state of charge ASOC .

[0158] It is noted that the value of such di f ference of state of charge ASOC is proportional to the integral of the current supplied to the battery, for example , to such raw target current supplied to the low-voltage battery isatt_Lv_Tgt_Raw, therefore , allowing to manage the dynamics so as to control the variation gradient of the state of charge ASOC .

[0159] For example , the relationship between such di f ference of state of charge ASOC and such raw target current supplied to the low-voltage battery isatt_Lv_Tgt_Raw, that is , such map 206c, may be calibrated according to the following relationships : i f SOCBatt LV Tgt> SOCBatt LV, then iBatt _LV Tgt_Raw > 0 / that is , the charging of the low-voltage battery is present ; i f SOCBatt LV Tgt< SOCBatt LV, then iBatt _LV Tgt_Raw < 0 / that is , the discharging of the low-voltage battery is present ; and i f SOCBatt LV Tgt= SOCBatt LV, then iBatt _LV Tgt_Raw=0 / that is , a condition of balance is maintained wherein the low-voltage battery is neither charged or discharged . In the condition wherein the raw target current supplied to the low-voltage battery isatt_Lv_Tgt_Raw is equal to zero , that is , when the target state of charge of the low-voltage battery SOCBatt_Lv_Tgt is equal to the current state of charge of the low-voltage battery SOCsatt_Lv, the DC-DC converter 100 is configured to supply energy only to the low-voltage auxiliary components , that is , it does not supply energy to the low-voltage battery .

[0160] In this condition, it is possible to reduce the flow of the currents traversing the low-voltage battery, thereby limiting the energy losses due to the Joule ef fect .

[0161] Therefore , a method according to the present description may comprise an operation of limiting, for example , performed via such block 206 , such current to be supplied to the low voltage battery, that is , the target current isatt_Lv_Tgt, through a current limit iBatt_Lv_Lim, preferably wherein such limiting operation is performed by selecting the minimum current between such current to be supplied to the low-voltage battery isatt_Lv_Tgt and such current limit , that is , the limit current iBatt_Lv_Lim described in the foregoing .

[0162] Moreover, the operation of determining such current to be supplied to the low-voltage battery isatt_Lv_Tgt performed in a method as described herein, for example , via the block 206 , may comprise :

[0163] - i f a fast charge indication of the first battery 104 , for example , the fast charge request of the low voltage battery LV_Batt_Fst_Chrg_Req, indicates to activate a fast charge mode , equalling such current to be supplied isatt_Lv_Tgt to a current related to such fast charge mode of the fist battery 104 ; or

[0164] - determining such current to be supplied isatt_Lv_Tgt as a function of such di f ference ASOC between the state of charge to be reached of the low-voltage battery S OCBatt_Lv_ gt and the current state of charge SOCBatt_Lv of the first battery, that is , such low-voltage battery 104 , preferably via extrapolation from a map that expresses currents to be supplied iBatt_Lv_ gt to the first battery 104 as a function of such di f ferences of state of charge ASOC .

[0165] The block diagram 20 of Figure 2 shows a definition block 208 of a target voltage related to the low-voltage side of the DC-DC converter 100 .

[0166] Such definition block 208 of the target voltage related to the low-voltage side of the DC-DC converter 100 may be configured to receive :

[0167] - the target current isatt_Lv_ gt of the low-voltage battery from the definition block 206 of the target current of the low-voltage battery;

[0168] - the first limit related to a minimum voltage VDcDc_Lv_Min of the low-voltage side of the DC-DC converter 100 from the definition block 204 of limit voltages of the low-voltage side of the DC-DC converter 100 ;

[0169] - the second limit related to a maximum voltage VocDc_Lv_Max of the low-voltage side of the DC-DC converter 100 from such definition block 204 of limit voltages of the low-voltage side of the DC-DC converter 100 ;

[0170] - the state of charge of the low-voltage battery SOCsatt_Lv, that is , a current state of charge of the low- voltage battery; and

[0171] - the current supplied to the low-voltage battery isatt_Lv, that is , a current being currently supplied to the low-voltage battery .

[0172] Such definition block 208 of the target voltage related to the low-voltage side of the DC-DC converter 100 may be further configured to provide as output a target voltage VDcDc_Lv_ gt on the low-voltage side of the DC-DC converter 100 .

[0173] Figure 8 shows a definition block 208 of a target voltage VDcDc_Lv_Tgt related to the low-voltage side o f the DC-DC converter 100 according to embodiments of the present description .

[0174] Such target voltage VDcDc_Lv_Tgt related to the low- voltage side of the DC-DC converter 100 may be obtained via an open loop control 208cand a closed loop control 208d, respecting both the first limit of minimum voltage VDcDc_Lv_Min and the second limit of maximum voltage VDcDc_Lv_Max (both related to the low-voltage side o f the DC-DC converter 100 ) , for example , by performing operations of limiting via a limitation unit 208a, such target voltage VDcDc_Lv_Tgt being the voltage which enables reaching the target current isatt_Lv_Tgt being supplied to the low-voltage battery and being used to limit the budget of power reserved for the supply of such low- voltage battery, that is , being a target voltage applied to the low-voltage battery in such a way as to obtain the desired target current supplied to such battery .

[0175] The limitation unit 208amay be configured to :

[0176] - limit the value which can be taken by such target voltage VDcDc_Lv_Tgt related to the low-voltage side o f the DC-DC converter 100 to a maximum value equal to the received maximum voltage VDcDc_Lv_Max of the low-voltage side of the DC-DC converter 100 ; and

[0177] - limit the value which can be taken by such target voltage VDcDc_Lv_Tgt related to the low-voltage side o f the DC-DC converter 100 to a minimum value equal to the received minimum voltage VDcDc_Lv_Min of the low-voltage side of the DC-DC converter 100 .

[0178] For example , an intermediate voltage related to such target voltage VDcDc_Lv_Tgt , for example , a value provided as output from a summation block 208b described in the following, may be limited via such operation of limitation to a minimum value .

[0179] Such operation of limitation to a minimum value may be performed via a voltage maximi zation block 208a2 configured to : receive , at a first input terminal , such intermediate voltage related to such target voltage VDCDC_LV_Tgt ,'

[0180] - receive , at a second input terminal , the minimum voltage VDcDc_Lv_Min of the low-voltage side of the DC-DC converter 100 ; and

[0181] - provide as output , for example , via an output terminal , the voltage having the higher value out of the intermediate voltage and the minimum voltage VDcDc_Lv_Min, that is , providing as output an intermediate voltage related to such target voltage VDcDc_Lv_Tgt limited to a minimum value .

[0182] Such operation of limitation to a maximum value may be performed via a voltage minimi zation block 208aiconfigured to : receive , at a first input terminal , such intermediate voltage related to such target voltage VDcDc_Lv_Tgt limited to a minimum value ;

[0183] - receive , at a second input terminal , the maximum voltage VDcDc_Lv_Max of the low-voltage side of the DC-DC converter 100 ; and

[0184] - provide as output , for example , via an output terminal , the voltage having the lower value out of the intermediate voltage limited to a minimum value and the maximum voltage VDcDc_Lv_Max, that is , providing as output a voltage which is limited both to a minimum value and to a maximum value , that is , such target voltage VDCDC_LV_Tgt •

[0185] Therefore , such intermediate voltage related to such target voltage VDcDc_Lv_Tgt, for example , such value provided as output from the summation block 208b, is limited both by the first limit related to the minimum voltage VDcDc_Lv_Min of the low-voltage side of the DC-DC converter 100 and by the second limit related to the maximum voltage VDcDc_Lv_Max of the low-voltage side of the DC-DC converter 100 .

[0186] The summation block 208b may be configured to :

[0187] - receive an open loop voltage VDcDc_Lv_oL_Tgt from the open loop control 208c;

[0188] - receive a closed loop voltage VDcDc_Lv_cL_Tgt from the closed loop control 208d,'

[0189] - sum such open loop voltage VDcDc_Lv_oL_Tgt to such closed loop voltage VDcDc_Lv_cL_Tgt, thereby obtaining such intermediate voltage related to such target voltage VDCDc_Lv_Tgt ; and provide as output such intermediate voltage related to such target voltage VDcDc_Lv_Tgt .

[0190] The open loop control 208cmay be configured to receive the current state of charge of the low-voltage battery SOCsatt_Lv and the target current isatt_Lv_Tgt of the low-voltage battery, and to provide as output the openloop VOltage VDCDC LV OL Tgt -

[0191] Such open-loop control 208cmay be configured to obtain such open-loop voltage VDcDc_Lv_oL_Tgt by extrapolation, for example , from a map 208ci, based on the received current state of charge of the low-voltage battery SOCsatt_Lv and on the received target current isatt_Lv_Tgt of the low-voltage battery .

[0192] In fact , such map 208ci, for example , stored in a memory of an electronic control unit of the vehicle , may express values of open-loop voltages VDcDc_Lv_oL_Tgt as a function of values of states of charge of the low-voltage battery SOCsatt_Lv and of target currents isatt_Lv_Tgt of the low-voltage battery .

[0193] The closed loop control 208d may be configured to receive the first limit related to the minimum voltage VDcDc_Lv_Min and the second limit related to the maximum voltage VDcDc_Lv_Max, both related to the low-voltage side of the DC-DC converter 100 , the current being currently supplied to the low-voltage battery isatt_Lv, and the target current iBatt_Lv_Tgt of the low-voltage battery .

[0194] Such closed loop control 208d may be further configured to provide as output the closed-loop voltage VoCDC_LV_CL_Tgt •

[0195] Such closed loop control 208d may be configured to obtain such closed-loop voltage VDcDc_Lv_cL_Tgt through the sum of proportional and integral controls , for example , performed via a proportional-integral block PI 208di, based on a di f ference , for example , obtained via a subtraction operation performed via a current subtraction block 208d2 , between the target current i satt_Lv_Tgt and the current being currently supplied to the low-voltage battery isatt_Lv.

[0196] The result of such operation of summing proportional and integral controls , for example , performed via the proportional-integral block PI 208di, may be limited, that is , saturated, both via the minimum voltage VDcDc_Lv_Min , for example , received via a lower saturation terminal LS of the proportional-integral block PI 208di, and via the maximum voltage VDcDc_Lv_Max, for example , received via an upper saturation terminal HS of the proportional-integral block PI 208di .

[0197] Therefore , the operation of determining such voltage to be applied to such first battery 104 , that is , the target voltage VDcDc_Lv_Tgt, performed in a method as described herein, for example , via such block 208 , may comprise summing :

[0198] - an open loop voltage VDcDc_Lv_oL_Tgt obtained as a function of such current state of charge SOCsatt_Lv of the first battery 104 , that is , the low-voltage battery, and such current to be supplied to the low-voltage battery, that is , the target current isatt_Lv_Tgt; and

[0199] - a closed loop voltage VDcDc_Lv_cL_Tgt obtained by summing proportional and integral controls based on a di f ference between such current to be supplied to the low-voltage battery, that is , the target current iBatt_Lv_Tgt, and such current being currently supplied isatt_Lv to the first battery 104 , that is , to the low- voltage battery .

[0200] Moreover, a method according to the present description may comprise an operation of limiting, for example , performed via such block 208 , such voltage to be applied to such first battery 104 , that is , the target voltage VDcDc_Lv_Tgt, through such first voltage limit , that is , such maximum voltage VDcDc_Lv_Max, and such second voltage limit , that is , such minimum voltage VDcDc_Lv_Min, preferably wherein such limiting operation is performed by selecting as the first limited voltage the minimum voltage out of such voltage to be applied to such first battery VDcDc_Lv_Tgt and such first voltage limit VDCDC_LV_MSX , and by selecting as the limited voltage to be applied to such first battery, for example , as limited target voltage VDcDc_Lv_Tgt , the maximum voltage out of such first limited voltage and such second voltage limit VDcDc_Lv_Min .

[0201] The block diagram 20 of Figure 2 shows a definition block 210 of a limit current related to the high-voltage side of the DC-DC converter 100 .

[0202] Such definition block 210 of the limit current related to the high-voltage side of the DC-DC converter 100 may be configured to receive a voltage VDCDC_HV related to the high-voltage side of the DC-DC converter 100 and a limit , that is , maximum, electrical power EDCDC Limabsorbable by the high-voltage side of the DC-DC converter DC-DC 100 .

[0203] Such definition block 210 of the limit current related to the high-voltage side of the DC-DC converter 100 may be further configured to provide as output a limit , that is , maximum, current iDCDc_Hv_Lim absorbable by the high-voltage side of the DC-DC converter 100 .

[0204] For example , such limit current iDCDc_Hv_Lim absorbable by the high-voltage side of the DC-DC converter 100 may be obtained via the following equation :

[0205] For example , such voltage VDCDC_HV related to the high-voltage side of the DC-DC converter 100 may be measured via the DC-DC converter 100 itsel f .

[0206] Therefore , a method according to the present description may comprise an operation of limiting, for instance , performed via such block 210 , the current to be drawn from the second battery, for example , the limit current iDCDc_Hv_Lim absorbable by the high-voltage side of the DC-DC converter 100 .

[0207] Such limitation operation may allow to obtain such limited current to be drawn from the second battery iDCDc_Hv_Lim by dividing the electrical power absorbable from such second battery, for example , the limit electrical power EDCDC Limabsorbable by the high-voltage side of the DC-DC converter 100 , by a voltage applied to such second battery VDCDC_HV, that is , a voltage related to the high-voltage side of the DC-DC converter 100 .

[0208] Therefore , the target voltage VDcDc_Lv_ gt related to the low-voltage side of the DC-DC converter may be used to limit the budget of power reserved for supplying the low-voltage battery, whereas the limit current iDCDc_Hv_Lim absorbable by the high-voltage side of the DC-DC converter 100 corresponds to the maximum absorbable current , that is , the maximum current supplied in input to the DC-DC converter .

[0209] In fact , such target voltage VDcDc_Lv_ gt related to the low-voltage side of the DC-DC converter, when applied to the low-voltage battery 104 , is such as to enable reaching the desired target current isatt_Lv_ gt supplied to such low-voltage battery 104 .

[0210] It is noted that the target voltage VDcDc_Lv_ gt used to limit the budget of power reserved for supplying the low-voltage battery and the limit current iDCDc_Hv_Lim absorbable by the high-voltage side of the DC-DC converter 100 may be controlled separately .

[0211] Therefore , it is possible to vary via the DC-DC converter 100 :

[0212] - the power supplied to the low-voltage battery separately with respect to the power supplied to the auxiliary components , by varying the target voltage VDCDc_Lv_ gt, and

[0213] - the power trans ferred from the high-voltage side to the low-voltage side of the DC-DC converter 100 , by varying the limit current iDCDc_Hv_Lim absorbable by the high-voltage side of the DC-DC converter 100 .

[0214] It is also noted that i f the power trans ferable from the high-voltage side to the low-voltage side of the DC-DC converter 100 is limited via the limit current iDCDc_Hv_Lim absorbable by the high-voltage side of the DC- DC converter 100 , it is possible , as described in the foregoing, to lose control of the target voltage VDcDc_Lv_gt related to the low-voltage battery 104 .

[0215] Therefore , such limitation may be performed only in critical energy conditions , for example , when a further discharge of the high-voltage battery would lead to its damaging, in order to avoid damaging such high-voltage battery .

[0216] Figure 9 shows an exemplary flow diagram 60 of a method for controlling a DC-DC converter 100 in a vehicle having an electric traction motor according to embodiments of the present description .

[0217] In a first step 600 of the method 60 , the current absorbable by the high-voltage side of the DC-DC converter 100 may be limited via the limit current iDCDc_Hv_Lim described in the foregoing, obtained as a function of a limit electrical power EDCDC Limabsorbable by the high-voltage side of the DC-DC converter 100 , for example , an electrical power defined by an electronic control unit of the vehicle as a limit absorbable by the DC-DC converter 100 .

[0218] Optionally, in a second step 602 , the target state of charge of the low-voltage battery SOCBatt_Lv_ gt may be defined based on a driving mode Drv_Mod ( for example , based on the target state of charge related to the current driving mode SOC gt_DrvMod) and on a charge request , for instance , full , of the high-voltage battery Full_Chrg_Req ( for example , based on the maximum state of charge reachable by such high-voltage battery S OC gt_HVBatChrg ) •

[0219] Optionally, in a third step 604 , the limit current iBatt_Lv_Lim of the low-voltage battery, that is , a maximum value of the current supplied to the low-voltage battery isatt_Lv, may be obtained as a function of the maximum value of electrical power EBatt LV Limrelated to a supply of the low-voltage battery, for example , an electrical power indicating a limit budget of electrical power which can be currently used .

[0220] In a fourth step 606 , the target current isatt_Lv_ gt of the low-voltage battery, that is , a target current supplied to the low-voltage battery, may be obtained as a function :

[0221] - of the di f ference between the target state of charge of the low-voltage battery SOCBatt_Lv_ gt obtained in the second step 602 and of a current state of charge SOCsatt_Lv of the low-voltage battery; and

[0222] - of the fast charge request of the low-voltage battery LV_Batt_Fst_Chrg_Req, i f present .

[0223] Optionally, such target current isatt_Lv_ gt of the low-voltage battery may be limited, in such fourth step 606 , by the limit current iBatt_Lv_Lim of the low-voltage battery obtained in the third step 604 .

[0224] Optionally, in a fi fth step 608 it is possible to obtain the first limit related to the minimum voltage VDcDc_Lv_Min of the low-voltage side of the DC-DC converter 100 and the second limit related to the maximum voltage VDcDc_Lv_Max of the low-voltage side of the DC-DC converter 100 , for example , defined in such a way as to achieve the requested performances in the auxiliary components 106 , to prevent the aging of the low-voltage battery 104 , and to prevent gasi fication problems of such low- voltage battery 104 .

[0225] In a sixth step 610 , the target voltage VDcDc_Lv_Tgt related to the low-voltage side of the DC-DC converter may be obtained based on the current state of charge SOCBatt_Lv of the low-voltage battery, on a current being currently supplied to the low-voltage battery isatt_Lv, and on the target current isatt_Lv_Tgt of the low-voltage battery obtained in the fourth step 606 .

[0226] It is noted that such target voltage VDcDc_Lv_Tgt is a voltage used to limit the budget of power reserved for supplying the low-voltage battery .

[0227] Optionally, such target voltage VDcDc_Lv_Tgt related to the low-voltage side of the DC-DC converter and used to limit the budget of power reserved for supplying the low-voltage battery may be limited, in such sixth step 610 , via the first limit related to the minimum voltage VDcDc_Lv_Min and the second limit related to the maximum voltage VDcDc_Lv_Max, both related to the low-voltage side of the DC-DC converter 100 and obtained in the fi fth step 608 .

[0228] Therefore , the solution described in detail herein allows to obtain a method for controlling a DC-DC converter 100 comprised in a vehicle having an electric traction motor, such vehicle comprising a first battery, that is, a low-voltage battery, 104 having a first supply voltage, for example, of about 12 volts, and a second battery, that is, a high-voltage battery, having a second supply voltage, such second supply voltage being higher than the first supply voltage, for example, a supply voltage of about 800 volts, wherein such DC-DC converter 100 is configured to transfer energy from such second battery to such first battery 104.

[0229] Such method comprises:

[0230] - limiting, for example, via the definition block 210 of the limit current related to the high-voltage side of the DC-DC converter 100, for example, in a step 600, a current to be drawn, via the DC-DC converter 100, from the second battery as a function of an electrical power absorbable from such second battery, for example, such limit electrical power EDCDC Limabsorbable by the high-voltage side of the DC-DC converter 100, thereby obtaining a limited current to be drawn, for example, the limit current iDCDc_Hv_Lim; determining, for example, via the definition block 206 of the target current of the low-voltage battery, for example, in a step 606, a current to be supplied, for example, the target current isatt_Lv_ gt of the low-voltage battery, via the DC-DC converter 100, to such first battery 104 as a function of a difference ASOC between a state of charge to be reached by the low voltage battery, that is, a target state of charge of the low-voltage battery SOCBatt_Lv_ gt, and a current state of charge SOCsatt_Lv of the first battery 104; and determining, for example, via the definition block 208 of a target voltage VDcDc_Lv_ gt related to the low-voltage side of the DC-DC converter 100, for example, in a step 610, a voltage to be applied, for example, the target voltage VDcDc_Lv_ gt related to the low-voltage side of the DC-DC converter, via the DC-DC converter 100, to such first battery 104 as a function of the current state of charge SOCBatt_Lv of the first battery, of a current currently supplied isatt_Lv to the first battery 104 , and of the determined current to be supplied iBatt_Lv_ gt .

[0231] Therefore , it is evident that the solution described in the present detailed description may favour a control of the power supplied to the low-voltage battery separately from the power supplied to auxiliary components , thereby improving the performances of the vehicle .

[0232] Speci fically, the electrical power drawn by the low-voltage battery may be reduced dynamically during the acceleration of the vehicle , without af fecting the auxiliary components . The electrical power saved in this way may therefore be used for the propulsion of the vehicle .

[0233] In addition, it is possible to save energy since , when the target state of charge is reached, the current flow traversing the low-voltage battery is reduced, thereby preventing an energy waste due to the Joule ef fect .

[0234] Further advantages of solutions as described herein are :

[0235] - the reduction of early aging of the low-voltage battery, since minimum voltage requirements are met ;

[0236] - the prevention of gasi fication problems of the low-voltage battery, since maximum voltage requirements are met ; and

[0237] - the fact that the auxiliary components may operate in conditions which enable satis fying requested performances .

[0238] It is noted that embodiments of the present description refer to a corresponding vehicle having an electric traction motor and comprising :

[0239] - at least one DC-DC converter 100 , - at least one electronic control unit ,

[0240] - at least one first battery, that is , at least one low-voltage battery 104 , having a first supply voltage , for example , of about 12 volts , and

[0241] - at least one second battery, that is , a high- voltage battery, having a second supply voltage , such second supply voltage being higher than the first supply voltage , for example , a supply voltage of about 800 volts .

[0242] Such DC-DC converter 100 comprised in such vehicle is configured to trans fer energy from such second battery to such first battery 104 , and such at least one electronic control unit comprised in such vehicle is configured to perform the steps of the method described in the foregoing .

[0243] Without prej udice to the basic principles , the details and the embodiments may vary, even appreciably, with respect to what has been described, by way of example only, without departing from the extent of protection .

[0244] The extent of protection is defined by the annexed claims .

Claims

CLAIMS1. Method (60) for controlling a DC-DC converter (100) comprised in a vehicle having an electric traction motor, said vehicle comprising a first battery (104) having a first supply voltage, and a second battery having a second supply voltage, said second supply voltage being higher than the first supply voltage, wherein said DC-DC converter (100) is configured to transfer energy from said second battery to said first battery (104) ; said method (60) comprising: limiting (600; 210) a current to be drawn, via the DC-DC converter (100) , from the second battery as a function of an electrical power {EDCDC Lim) absorbable from said second battery, obtaining a limited current to be drawn ( iDCDc_Hv_Lim) ; determining (606; 206) a current to be supplied ( iBatt_Lv_Tgt) , via the DC-DC converter (100) , to said first battery (104) as a function of a difference (ASOC) between a state of charge to be reached by the first battery ( SOCBatt_Lv_Tgt) and a current state of charge (SOCsatt_Lv) of the first battery (104) ; and determining (610; 208) a voltage to be applied (VocDc_Lv_Tgt) , via the DC-DC converter (100) , to said first battery (104) as a function of the current state of charge (SOCsatt_Lv) of the first battery (104) , a current currently supplied (isatt_Lv) to the first battery (104) , and the determined current to be supplied (isatt_Lv_Tgt) .

2. The method (60) according to claim 1, wherein the operation of limiting (600; 210) the current to be drawn from the second battery comprises obtaining said limited current to be drawn ( iDCDc_Hv_Lim) by dividing said electrical power {EDCDC Lim) absorbable from said secondbattery by a voltage applied to said second battery(VDCDC_HV) •3. The method (60) according to claim 1 or claim 2, wherein said method (60) comprises determining (602; 200) said state of charge to be reached ( SOCBatt_Lv_Tgt) by the first battery (104) : if a charging indication ( Full_Chrg_Req) of the second battery indicates that said second battery is in a charging state, equalling said state of charge to be reached ( SOCBatt_Lv_Tgt) to a maximum state of charge ( SOCTgt_HVBatchrg) reachable by said first battery (104) ; or as a function of a driving mode (Drv_Mod) of said vehicle, preferably via extrapolation from a map (200b) that express states of charge to be reached ( SOCBatt_Lv_Tgt) of the first battery (104) as a function of driving modes (Drv_Mod) .

4. The method (60) according to any of the previous claims, wherein said method (60) comprises determining (604; 202) a current limit ( iBatt_Lv_Lim) by dividing an additional electrical power (EBatt LV Lim) stored in said first battery (104) by a voltage currently being output (VDCDC_LV) from the DC-DC converter (100) ; wherein, preferably, a result of said division operation is further multiplied by a conversion efficiency (IJDCDC') of the DC-DC converter (100) .

5. The method (60) according to claim 4, wherein said method (60) comprises limiting (606; 206) said determined current to be supplied ( isatt_Lv_Tgt) through said current limit ( iBatt_Lv_Lim) , preferably wherein said limiting operation (606; 206) comprises selecting the minimum current between said determined current to be supplied ( iBatt_Lv_Tgt) and said current limit ( iBatt_Lv_Lim) .

6. The method (60) according to any of the previous claims, wherein said current to be supplied ( isatt_Lv_Tgt) to said first battery (104) is determined (606; 206) : if a fast charge indication (LV_Batt_Fst_Chrg_Req) of the first battery (104) indicates to activate a fast charge mode, equalling said current to be supplied ( isatt_Lv_Tgt) to a current related to said fast charge mode of the first battery (104) ; or as a function of said difference (ASOC) between the state of charge to be reached ( SOCsatt_Lv_Tgt) and the current state of charge (SOCsatt_Lv) of the first battery (104) , preferably via extrapolation from a map that express currents to be supplied ( isatt_Lv_Tgt) to the first battery (104) as a function of said differences (ASOC) .

7. The method (60) according to any of the previous claims, wherein said voltage to be applied ( VDcDc_Lv_Tgt ) to said first battery (104) is determined (610; 208) as a sum of: an open loop voltage (VDcDc_Lv_oL_Tgt) obtained as a function of said current state of charge (SOCsatt_Lv) of the first battery (104) and said determined current to be supplied ( isatt_Lv_Tgt) ; and a closed loop voltage (VDcDc_Lv_cL_Tgt) obtained by summing proportional and integral controls based on a difference between said determined current to be supplied ( isatt_Lv_Tgt) and said current currently supplied ( iBatt_LV ) to the first battery (104) .

8. The method (60) according to any of the previous claims, wherein said method (60) comprises determining (608; 204) : a first voltage limit (VDcDc_Lv_Max) as a function ofa temperature (TBatt LV ) of the first battery (104) ; and / or a second voltage limit (VBcDc_Lv_Min) as a function of said temperature (TBatt_Lv) of the first battery (104) , said current state of charge (SOCBatt_Lv) of the first battery (104) , preferably an indication of activation of a defrost function (Def rost_Act_Req) of the vehicle, and preferably a given speed of components (Comp_Spd_Tgt ) of the vehicle operating at said given speed.

9. The method (60) according to claim 8, wherein said method (60) comprises limiting (610; 208) said determined voltage to be applied (VBcDc_Lv_Tgt) through said first voltage limit (VBcDc_Lv_Max) and said second voltage limit ( VDcDc_Lv_Min ) , preferably wherein said limiting operation (610; 208) comprises selecting as intermediate voltage the minimum voltage between said determined voltage to be applied (VBcDc_Lv_Tgt) and said first voltage limit (VDcDc_Lv_Max) , and selecting as limited voltage to be applied (VBcDc_Lv_Tgt) the maximum voltage between said intermediate voltage and said second voltage limit ( VDCDC_LV_Min ) •10. Vehicle having an electric traction motor, said vehicle comprising at least one DC-DC converter (100) , at least one electronic control unit, at least one first battery (104) having a first supply voltage, and at least one second battery having a second supply voltage, said second supply voltage being higher than the first supply voltage, wherein said DC-DC converter (100) is configured to transfer energy from said second battery to said first battery (104) , and wherein said at least one electronic control unit is configured to perform the steps of the method (60) according to any of the previous claims.

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