Patent Publication Number: US-2023138760-A1

Title: Circuit and method for providing multi-mode electrical power to an electrical load in a vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims foreign priority benefits under 35 U.S.C. §119(a)-(d) to CN patent application 202111301788.6 filed Nov. 4, 2021, the disclosure of which is hereby incorporated by reference in its entirety. 
     TECHNICAL FIELD 
     The following relates to a circuit and method for providing multi-mode electrical power to an electrical load in a vehicle. 
     BACKGROUND 
     A topology of a high-voltage (HV) architecture for an electric vehicle may include duplicate circuits each including a HV (e.g., 400 volts) voltage source, a main positive relay conecting a positive side of the HV voltage source to an electrical load (e.g., a direct current (DC) link capacitor), a main negative relay connecting a negative side of the HV voltage source to the electrical load, and a pre-charge relay connected in parallel with the main positive relay. Such a topology may also include a relay connecting the positive side of one HV voltage source to the negative side of the other HV voltage source. 
     In such a topology, by providing different configurations of open or closed states of the various relays, the electrical load may be connected individually to one or the other HV voltage source, to both connected in series, or to both connected in parallel. However, the duplication of circuits in such a topology increases the cost as well as the number of possible failure points (e.g., a “stuck open” (i.e., welded) or “stuck closed” relay) associated therewith. Such a topology also requires a complex relay control sequence for detecting the status of relays and providing individual, series, or parallel connection of the HV voltage source(s) to the vehicle electrical load. 
     As a result, there exists a need for an improved circuit and method for providing multi-mode electrical power to an electrical load in a vehicle. Such an improved circuit and method would provide a topology of a HV architecture for an electric vehicle that would reduce the number of components needed, thereby reducing both cost and the number of possible failure points associated therewith. Such an improved circuit and method would also provide a simplified and/or improved relay control sequence for detecting the status of relays and providing multiple modes of power to a vehicle electrical load. 
     SUMMARY 
     According to one non-limiting exemplary embodiment described herein, a circuit for providing multi-mode electrical power to a load in a vehicle is provided. The circuit comprises a first voltage source having a positive side and a negative side, a second voltage source having a positive side and a negative side, a main positive relay having a first side and a second side, the second side of the main positive relay connected to a first side of the load, and a main negative relay having a first side and a second side, the second side of the main negative relay connected to a second side of the load. The circuit further comprises a first relay operable between an open position and a closed position, the first relay having a first side and a second side, the first side of the first relay connected to the positive side of the first voltage source, and the second side of the first relay connected to the negative side of the second voltage source. The circuit further comprises a second relay operable between an open position and a closed position, the second relay having a first side and a second side, the first side of the second relay connected to the positive side of the first voltage source, and the second side of the second relay connected to the positive side of the second voltage source and the first side of the main positive relay. The circuit further comprises a third relay operable between an open position and a closed position, the third relay having a first side and a second side, the first side of the third relay connected to the negative side of the second voltage source, and the second side of the third relay connected to the first side of the main negative relay. 
     According to another non-limiting exemplary embodiment described herein, a method for providing multi-mode electrical power to a load in a vehicle is provided, the vehicle having a first voltage source and a second voltage source, the load having a first side and a second side, the first voltage source having a positive side and a negative side, and the second voltage source having a positive side and a negative side. The method comprises connecting a main positive relay having a first side and second side to the vehicle load by connecting the second side of the main positive relay to the first side of the load, and connecting a main negative relay having a first side and second side to the vehicle load by connecting the second side of the main negative relay to the second side of the load. The method further comprises connecting a first relay having a first side and a second side to the first voltage source and the second voltage source by connecting the first side of the first relay to the positive side of the first voltage source and connecting the second side of the first relay to the negative side of the second voltage source. The method further comprises connecting a second relay having a first side and a second side to the first voltage source, the second voltage source, and the main positive relay by connecting the first side of the second relay to the positive side of the first voltage source and connecting the second side of the second relay to the positive side of the second voltage source and the first side of the main positive relay. The method further comprises connecting a third relay having a first side and a second side to the second voltage source and the main negative relay by connecting the first side of the third relay to the negative side of the second voltage source and connecting the second side of the third relay to the first side of the main negative relay, wherein each of the first, second, and third relays is independently operable between an open position and a closed position. The method further comprises providing electrical power from the first voltage source and/or the second voltage source to the vehicle load according to one of a plurality of operating modes by opening or closing each of the first, second, and third relays. 
     According to another non-limiting exemplary embodiment described herein, a non-transitory computer readable storage medium is provided having stored computer executable instructions for providing multi-mode electrical power to a load in a vehicle, the vehicle comprising (i) a first voltage source having a positive side and a negative side, (ii) a second voltage source having a positive side and a negative side, (iii) a main positive relay having a first side and a second side, the second side of the main positive relay connected to a first side of the load, (iv) a main negative relay having a first side and a second side, the second side of the main negative relay connected to a second side of the load, (v) a first relay operable between an open position and a closed position, the first relay having a first side and a second side, the first side of the first relay connected to the positive side of the first voltage source, and the second side of the first relay connected to the negative side of the second voltage source, (vi) a second relay operable between an open position and a closed position, the second relay having a first side and a second side, the first side of the second relay connected to the positive side of the first voltage source, and the second side of the second relay connected to the positive side of the second voltage source and the first side of the main positive relay, (vii) a third relay operable between an open position and a closed position, the third relay having a first side and a second side, the first side of the third relay connected to the negative side of the second voltage source, and the second side of the third relay connected to the first side of the main negative relay, and (viii) a controller configured to independently control operation of the first, second, and third relays between open and closed positions. The computer executable instructions are configured to cause the controller to provide electrical power from the first voltage source and/or the second voltage source to the vehicle load according to one of a plurality of operating modes based on the open or closed positions of the first, second, and third relays. 
     A detailed description of these and other non-limiting exemplary embodiments of a circuit and method for providing multi-mode electrical power to an electrical load in a vehicle is set forth below together with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  is a simplified schematic diagram of a known topology for a high-voltage architecture for providing electrical power to an electrical load in a vehicle; 
         FIG.  1 B  is an exemplary, simplified schematic diagram of one exemplary embodiment of a topology for a high-voltage architecture for providing electrical power to an electrical load in a vehicle according to the present disclosure; 
         FIGS.  2 A- 2 D  are exemplary, simplified schematic diagrams illustrating exemplary control of the relays shown in  FIG.  1 B  of the exemplary embodiment of a topology for a high-voltage architecture for providing electrical power to an electrical load in a vehicle according to the present disclosure; 
         FIG.  3 A  is an exemplary flowchart illustrating one exemplary embodiment of a control sequence for the relays as shown in  FIG.  2 A  of the exemplary embodiment of a topology for a high-voltage architecture for providing electrical power to an electrical load in a vehicle according to the present disclosure; 
         FIG.  3 B  is an exemplary flowchart illustrating one exemplary embodiment of a control sequence for the relays as shown in  FIGS.  2 B and  2 D  of the exemplary embodiment of a topology for a high-voltage architecture for providing electrical power to an electrical load in a vehicle according to the present disclosure; and 
         FIG.  3 C  is an exemplary flowchart illustrating one exemplary embodiment of a control sequence for the relays as shown in  FIGS.  2 C and  2 D  of the exemplary embodiment of a topology for a high-voltage architecture for providing electrical power to an electrical load in a vehicle according to the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     As required, detailed non-limiting embodiments are disclosed herein. However, it is to be understood that the disclosed embodiments are merely exemplary and may take various and alternative forms. The figures are not necessarily to scale, and features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art. 
     With reference to Figures, a more detailed description of non-limiting exemplary embodiments of a circuit and method for providing multi-mode electrical power to an electrical load in a vehicle will be provided. For ease of illustration and to facilitate understanding, like reference numerals may be used herein for like components and features throughout the drawings. 
       FIG.  1 A  is a simplified schematic diagram of a known topology  10  for a high-voltage (HV) architecture for providing electrical power to an electrical load  18  in a vehicle. As seen therein, the topology  10  may include duplicate circuits each including a HV (e.g., 400 volts) voltage source,  14   a  and  14   b , each of which may have an associated current voltage sensor (CVS),  15   a  and  15   b . Each circuit in the topology  10  may also include a main positive relay  16   a  (Relay B) and  16   b  (Relay E), connecting a positive side of its respective HV voltage source,  14   a  and  14   b , to an electrical load  18 , e.g., a direct current (DC) link capacitor. Each circuit may also include a main negative relay  20   a  (Relay D) and  20   b  (Relay G), connecting a negative side of its respective HV voltage source,  14   a  and  14   b , to the electrical load  18 . Each circuit may also include a pre-charge relay  22   a  (Relay C) and  22   b  (Relay F), connected in parallel with its respective main positive relay  16   a  (Relay B) and  16   b  (Relay E). Such a topology may also include a relay  24  connecting the positive side of voltage source  14   b  to the negative side of voltage source  14   a . 
     In such a topology  10 , by providing different configurations of open or closed states of the various relays  16   a ,  16   b ,  20   a ,  20   b ,  22   a ,  22   b ,  24 , the electrical load  18  may be connected individually to voltage source  14   a  or  14   b , or to both voltage source  14   a  and voltage source  14   b  connected in series, or to both voltage source  14   a  and voltage source  14   b  connected in parallel. In that regard, as is known to those of ordinary skill in the art, each of the relays  16   a ,  16   b ,  20   a ,  20   b ,  22   a ,  22   b ,  24  is operable between or to an open position and a closed position. It is also noted that a controller (not shown) may be provided in communication with the relays  16   a ,  16   b ,  20   a ,  20   b ,  22   a ,  22   b ,  24  and configured to generate one or more control signals for operating or to operate each of the relays  16   a ,  16   b ,  20   a ,  20   b ,  22   a ,  22   b ,  24  between or to its respective open or closed position or state. 
     More specifically, still referring to  FIG.  1 A , closing relays  16   a  (Relay B) and  20   a  (Relay D) while opening relays  24  (Relay A),  16   b  (Relay E),  22   b  (Relay F), and  20   b  (Relay G) will connect only voltage source  14   a  to the electrical load  18 . Similarly, closing relays  16   b   (Relay E) and  20   b  (Relay G) while opening relays  24  (Relay A),  16   a  (Relay B),  22   a  (Relay C), and  20   a  (Relay D) will connect only voltage source  14   b  to the electrical load  18 . Moreover, closing relays  16   a  (Relay B),  20   a  (Relay D),  16   b  (Relay E), and  20   b  (Relay G) while opening relay  24  (Relay A) will connect voltage source  14   a  and voltage source  14   b  in parallel to the electrical load  18 . Furthermore, closing relays  24  (Relay A),  16   a  (Relay B), and  20   b  (Relay G) while opening relays  20   a  (Relay D),  16   b  (Relay E), and  22   b  (Relay F) will connect voltage source  14   a  and voltage source  14   b  in series to the electrical load  18 . 
     However, the duplication of circuits in topology  10  increases the cost as well as the number of possible failure points (e.g., a “stuck open” (i.e., welded) or a “stuck closed” relay ( 16   a ,  16   b ,  20   a ,  20   b ,  22   a ,  22   b ,  24 )) associated therewith. Topology  10  also requires a complex relay control sequence for detecting the status of relays  16   a ,  16   b ,  20   a ,  20   b ,  22   a ,  22   b ,  24  and providing individual, series, or parallel connection of voltage source  14   a  and voltage source  14   b  to the vehicle electrical load  18 . 
     As a result, there exists a need for an improved circuit and method for providing multi-mode electrical power to an electrical load in a vehicle. Such an improved circuit and method would provide a topology of a HV architecture for an electric vehicle that would reduce the number of components needed, thereby reducing both cost and the number of possible failure points associated therewith. Such an improved circuit and method would also provide a simplified and/or improved relay control sequence for detecting the status of relays and providing multiple modes of power to a vehicle electrical load. 
     In that regard,  FIG.  1 B  is an exemplary, simplified schematic diagram of one exemplary embodiment of a topology  50  for a high-voltage architecture for providing electrical power to an electrical load  52  in a vehicle according to the present disclosure. As seen therein, the topology  50  may include a circuit for providing multi-mode electrical power to a load  52  in a vehicle, e.g., a DC link capacitor. The circuit may comprise a first voltage source,  54   a , having a positive side and a negative side, and a second voltage source,  54   b , having a positive side and a negative side. The circuit may further comprise a main positive relay  56  (Relay B) having a first side and a second side. The second side of the main positive relay  56  (Relay B) may be connected to a first side of the load  52 . The circuit may still further comprise a main negative relay  60  (Relay F) having a first side and a second side. The second side of the main negative relay  60  (Relay F) may be connected to a second side of the load  52 . 
     The circuit may also comprise a first relay  62  (Relay A) having a first side and a second side. The first side of the first relay  62  (Relay A) may be connected to the positive side of the first voltage source  54   a , and the second side of the first relay  62  (Relay A) may be connected to the negative side of the second voltage source  54   b . The circuit may further comprise a second relay  64  (Relay E) having a first side and a second side. The first side of the second relay  64  (Relay E) may be connected to the positive side of the first voltage source  54   a , and the second side of the second relay  64  (Relay E) may be connected to the positive side of the second voltage source  54   b  and the first side of the main positive relay  56  (Relay B). The circuit may still further comprise a third relay  66  (Relay D) having a first side and a second side. The first side of the third relay  66  (Relay D) may be connected to the negative side of the second voltage source  54   b , and the second side of the third relay  66  (Relay D) may be connected to the first side of the main negative relay  60  (Relay F). The circuit may also comprise a pre-charge relay  68  (Relay C) which may be connected in parallel with the main positive relay  56  (Relay B). 
     Electrical power may be provided from the first voltage source  54   a  and/or the second voltage source  54   b  to the vehicle load  52  according to one of a plurality of operating modes based on the open or closed positions of the first relay  62  (Relay A), the second relay  64  (Relay E), and the third relay  66  (Relay D). Once again, as is known to those of ordinary skill in the art, each of the relays  56 ,  60 ,  62 ,  64 ,  66 ,  68  is operable between or to an open position and a closed position. In that regard, it is noted that  FIG.  1 B  illustrates all the relays  56 ,  60 ,  62 ,  64 ,  66 ,  68  in their respective open positions. 
     It is also noted that a controller  70  may be provided in communication with the relays  56 ,  60 ,  62 ,  64 ,  66 ,  68  via signal lines  56   s ,  60   s ,  62   s ,  64   s ,  66   s ,  68   s . The controller  70  may also be configured to generate one or more control signals and to transmit such control signals to the relays  56 ,  60 ,  62 ,  64 ,  66 ,  68  via signal lines  56   s ,  60   s ,  62   s ,  64   s ,  66   s ,  68   s  for operating or to operate each of the relays  56 ,  60 ,  62 ,  64 ,  66 ,  68  between or to its respective open or closed position or state. In that regard, the relays  56 ,  60 ,  62 ,  64 ,  66 ,  68  may be independently controlled between or to their respective open and closed positions, and the controller  70  may be configured to independently control operation of the relays  56 ,  60 ,  62 ,  64 ,  66 ,  68  between or to their respective open and closed positions. 
     As those skilled in the art will understand, the controller  70 , as well as any other controller, control unit, communication unit, system, subsystem, unit, module, interface, sensor, device, relay, switch, component, or the like described herein may individually, collectively, or in any combination comprise appropriate circuitry, such as one or more appropriately programmed processors (e.g., one or more microprocessors including central processing units (CPU)) and associated memory, storage media, or storage device(s), which may include stored operating system software and/or application software executable by the processor(s) for controlling operation thereof and for performing the particular algorithm or algorithms represented by the various methods, functions and/or operations described herein, including interaction between and/or cooperation with each other. One or more of such processors, as well as other circuitry and/or hardware, may be included in a single Application-Specific Integrated Circuitry (ASIC), or several processors and various circuitry and/or hardware may be distributed among several separate components, whether individually packaged or assembled into a System-on-a-Chip (SoC). The controller  70 , as well as any other controller, control unit, communication unit, system, subsystem, unit, module, interface, sensor, device, relay, switch, component, or the like described herein, may therefore comprise one or more processors and associated memory, storage media, or storage device having stored computer executable instructions for performing the particular algorithm or algorithms represented by the various methods, functions and/or operations described herein. In that regard, it is noted that the computer executable instructions described herein may be stored in or on a computer readable storage medium which may comprise any known type of storage medium or device and may be part of or associated with the controller  70 . 
       FIGS.  2 A- 2 D  are exemplary, simplified schematic diagrams illustrating exemplary control of the relays  56 ,  60 ,  62 ,  64 ,  66 ,  68  shown in  FIG.  1 B  of the exemplary embodiment of a topology  50  for a HV architecture for providing electrical power to an electrical load  52  in a vehicle according to the present disclosure. In that regard, while the controller  70  and signal lines  56   s ,  60   s ,  62   s ,  64   s ,  66   s ,  68   s  shown in  FIG.  1 B  have been omitted from each of  FIGS.  2 A- 2 D , it is noted that the relays  56 ,  60 ,  62 ,  64 ,  66 ,  68  shown in  FIGS.  2 A- 2 D  are nevertheless controlled by the controller  70  via signal lines  56   s ,  60   s ,  62   s ,  64   s ,  66   s ,  68   s , which have been omitted from  FIGS.  2 A- 2 D  solely to simplify those figures for ease of illustration. 
     Referring first to  FIG.  2 A , and with continuing reference to  FIG.  1 B , in one operating mode, the controller  70  may control the relays  56 ,  60 ,  62 ,  64 ,  66 ,  68  such that first relay  62  may be closed, the second relay  64  may be opened, and the third relay  66  may be opened to thereby connect the first and second voltage sources  54   a ,  54   b  to the load  52 , wherein the first and second voltage source  54   a ,  54   b  are connected in series. In that regard, a first current travels along the path labeled I 1  when the controller  70  controls the main positive relay  56  (and/or the pre-charge relay  68 ) as well as the main negative relay  60  to closed positions. In such a fashion, where each voltage source  54   a ,  54   b  is a 400-volt high-voltage battery or battery pack, an 800-volt compatible HV architecture is provided wherein a total of 800 volts is provided by voltage sources  54   a  and  54   b  to the load  52 . It is noted that the pre-charge relay  68  is shown in  FIG.  2 A  in an open position, having been controlled by the controller  70  to such a position after having been previously controlled by the controller  70  (along with the main negative relay  60 ) to a closed position to pre-charge the DC link capacitor  52 . After such a pre-charge of the DC link capacitor  52 , the controller  70  may then control the main positive relay  56  to its closed position and then control the pre-charge relay  68  to its open position. 
     Referring next to  FIG.  2 B , and with continuing reference to  FIG.  1 B , in another operating mode, the controller  70  may control the relays  56 ,  60 ,  62 ,  64 ,  66 ,  68  such that the first relay  62  may be opened, the second relay  64  may be opened, and the third relay  66  may be closed to thereby connect only the second voltage source  54   b  to the load  52 . In that regard, a second current travels along the path labeled I 2  when the controller  70  controls the main positive relay  56  (and/or the pre-charge relay  68 ) as well as the main negative relay  60  to closed positions. In such a fashion, where each voltage source  54   a ,  54   b  is a 400-volt high-voltage battery or battery pack, a total of 400 volts is provided by voltage source  54   b  to the load  52 . It is noted that the pre-charge relay  68  is shown in  FIG.  2 B  in an open position, having been controlled by the controller  70  to such a position after having been previously controlled by the controller  70  (along with the main negative relay  60 ) to its closed position to pre-charge the DC link capacitor  52 . After such a pre-charge of the DC link capacitor  52 , the controller  70  may then control the main positive relay  56  to its closed position and then control the pre-charge relay  68  to its open position. 
     Referring next to  FIG.  2 C , and with continuing reference to  FIG.  1 B , in another operating mode, the controller  70  may control the relays  56 ,  60 ,  62 ,  64 ,  66 ,  68  such that the first relay  62  may be opened, the second relay  64  may be closed, and the third relay  66  may be opened to thereby connect only the first voltage source  54   a  to the load  52 . In that regard, a third current travels along the path labeled I 3  when the controller  70  controls the main positive relay  56  (and/or the pre-charge relay  68 ) as well as the main negative relay  60  to closed positions. In such a fashion, where each voltage source  54   a ,  54   b  is a 400-volt high-voltage battery or battery pack, a 400-volt compatible HV architecture is provided wherein a total of 400 volts is provided by voltage source  54   a  to the load  52 . It is noted that the pre-charge relay  68  is shown in  FIG.  2 C  in an open position, having been controlled by the controller  70  to such a position after having been previously controlled by the controller  70  (along with the main negative relay  60 ) to its closed position to pre-charge the DC link capacitor  52 . After such a pre-charge of the DC link capacitor  52 , the controller  70  may then control the main positive relay  56  to its closed position and then control the pre-charge relay  68  to its open position. 
     Referring next to  FIG.  2 D , and with continuing reference to  FIG.  1 B , in another operating mode, the controller  70  may control the relays  56 ,  60 ,  62 ,  64 ,  66 ,  68  such that the first relay  62  may be opened, the second relay  64  may be closed, and the third relay  66  may be closed to thereby connect the first and second voltage sources  54   a ,  54   b  to the load  52 , wherein the first and second voltage sources  54   a ,  54   b  are connected in parallel. In that regard, the second and third currents I 2  and I 3  travel along the paths shown when the controller  70  controls the main positive relay  56  (and/or the pre-charge relay  68 ) as well as the main negative relay  60  to closed positions. In such a fashion, where each voltage source  54   a ,  54   b  is a 400-volt high-voltage battery or battery pack, a 400-volt compatible HV architecture is provided wherein a total of 400 volts is provided by voltage sources  54   a  and  54   b  to the load  52 . It is noted that the pre-charge relay  68  is shown in  FIG.  2 D  in an open position, having been controlled by the controller  70  to such a position after having been previously controlled by the controller  70  (along with the main negative relay  60 ) to its closed position to pre-charge the DC link capacitor  52 . After such a pre-charge of the DC link capacitor  52 , the controller  70  may then control the main positive relay  56  to its closed position and then control the pre-charge relay  68  to its open position. 
       FIG.  3 A  is an exemplary flowchart illustrating one exemplary embodiment of a control sequence  100  for the relays  56 ,  60 ,  62 ,  64 ,  66 ,  68  as shown in  FIG.  2 A  of the exemplary embodiment of a topology  50  for a HV architecture for providing electrical power to an electrical load  52  in a vehicle according to the present disclosure. As seen therein, and with continuing reference to  FIGS.  1 B and  2 A , after start  102 , the controller  70  may perform a status check  104  of the relays  56 ,  60 ,  62 ,  64 ,  66 ,  68  to determine  106  if any one or more of the relays  56 ,  60 ,  62 ,  64 ,  66 ,  68  is welded (i.e., “stuck closed”). If so, then the controller  70  may enter and/or may control the circuit and/or method to go to a state of HV power OFF  108 , such that no electrical power is provided to the load  52 . If not, then the controller  70  may generate a control signal for controlling the pre-charge relay  68  (Relay C) to a closed position  110  and then check  112  whether the status of the pre-charge relay  68  (Relay C) is “stuck open”. If so, then the controller  70  may enter and/or may control the circuit and/or method to go to the HV power OFF state  108 . 
     Otherwise, if the status of the pre-charge relay is not “stuck open”, then the controller  70  may generate a control signal for controlling the first relay  62  (Relay A) to a closed position  114  and then check  116  whether the status of the first relay  62  (Relay A) is “stuck open”. If so, then the controller  70  may enter and/or may control the circuit and/or method to go to the HV power OFF  108  state. If not, then the controller  70  may generate a control signal for controlling the main negative relay  60  (Relay F) to a closed position  120  and then check  122  whether the status of the main negative relay  60  (Relay F) is “stuck open”. If so, then the controller  70  may enter and/or may control the circuit and/or method to go to the HV power OFF  108  state. If not, a pre-charge operation  124  may begin and the controller  70  may then determine  126  whether a pre-charge timeout has occurred, i.e., whether a selected period of time has expired before a successful pre-charge of the DC link capacitor  52  has been performed. If so, then the controller  70  may enter and/or may control the circuit and/or method to go to the HV power OFF state  108 . 
     Alternatively, if the controller determines  126  that a pre-charge timeout has not occurred, then the controller may generate a control signal for controlling the main positive relay  56  (Relay B) to a closed position  128  and generate a control signal for controlling the pre-charge relay  68  (Relay C) to an open position  130 . The controller  70  may then check  132  whether the status of the main positive relay  56  (Relay B) is “stuck open”. If so, then the controller  70  may enter and/or may control the circuit and/or method to go to the HV power OFF  108  state. Otherwise, the controller  70  may enter and/or may control the circuit and/or method to go to a HV power ON state  134  such that both the first and the second voltage sources  54   a ,  54   b  are connected to and provide electrical power to the load  52 , wherein the first and second voltage source  54   a ,  54   b  are connected in series. 
       FIG.  3 B  is an exemplary flowchart illustrating one exemplary embodiment of a control sequence  200  for the relays  56 ,  60 ,  62 ,  64 ,  66 ,  68  as shown in  FIGS.  2 B and  2 D  of the exemplary embodiment of a topology  50  for a HV architecture for providing electrical power to an electrical load  52  in a vehicle according to the present disclosure. As seen therein, and with continuing reference to  FIGS.  1 B,  2 B, and  2 D , after start  202 , the controller  70  may perform a status check  204  of the relays  56 ,  60 ,  62 ,  64 ,  66 ,  68  to determine  206  if any one or more of the relays  56 ,  60 ,  62 ,  64 ,  66 ,  68  is welded (i.e., “stuck closed”). If so, then the controller  70  may enter and/or may control the circuit and/or method to go to a state of HV power OFF  208 , such that no electrical power is provided to the load  52 . If not, then the controller  70  may generate a control signal for controlling the pre-charge relay  68  (Relay C) to a closed position  210  and then check  212  whether the status of the pre-charge relay  68  (Relay C) is “stuck open”. If so, then the controller  70  may enter and/or may control the circuit and/or method to go to the HV power OFF state  208 . 
     Otherwise, if the status of the pre-charge relay is not “stuck open”, then the controller  70  may generate a control signal for controlling the third relay  66  (Relay D) to a closed position  214  and then check  216  whether the status of the third relay  66  (Relay D) is “stuck open”. If so, then the controller  70  may enter and/or may control the circuit and/or method to go to the HV power OFF state  208 . If not, then the controller  70  may generate a control signal for controlling the main negative relay  60  (Relay F) to a closed position  218  and then check  220  whether the status of the main negative relay  60  (Relay F) is “stuck open”. If so, then the controller  70  may enter and/or may control the circuit and/or method to go to the HV power OFF state  208 . If not, a pre-charge operation  222  may begin and the controller  70  may then determine  224  whether a pre-charge timeout has occurred, i.e., whether a selected period of time has expired before a successful pre-charge of the DC link capacitor  52  has been performed. If so, then the controller  70  may enter and/or may control the circuit and/or method to go to the HV power OFF state  208 . 
     Alternatively, if the controller  70  determines  224  that a pre-charge timeout has not occurred, then the controller  70  may generate a control signal for controlling the main positive relay  56  (Relay B) to a closed position  226  and generate a control signal for controlling the pre-charge relay  68  (Relay C) to an open position  228 . The controller  70  may then check  230  whether the status of the main positive relay  56  (Relay B) is “stuck open”. If so, then the controller  70  may enter and/or may control the circuit and/or method to go to the HV power OFF  208  state. If not, the controller  70  may then determine  232  if a parallel connection of the first and second voltage sources  54   a ,  54   b  to the load  52  should be fulfilled. If not, then the controller  70  may enter and/or may control the circuit and/or method to go to a HV power ON state  234  such that only the second voltage source  54   b  is connected to and provides electrical power to the load  52  (see  FIG.  2 B ). 
     Otherwise, if the controller  70  determines  232  that a parallel connection of the first and second voltage sources  54   a ,  54   b  to the load  52  should be fulfilled, then the controller  70  may generate a control signal for controlling the second relay  64  (Relay E) to a closed position  236 . The controller  70  may then check  240  whether the status of the second relay  64  (Relay E) is “stuck open”. If so, then the controller  70  may enter and/or may control the circuit and/or method to go to the HV power OFF state  208 . If not, then the controller  70  may enter and/or may control the circuit and/or method to go to the HV power ON state  234 , such that both the first and second voltage sources  54   a ,  54   b  are connected to and provide electrical power to the load  52 , wherein the first and second voltage sources  54   a ,  54   b  are connected in parallel (see  FIG.  2 D ). 
       FIG.  3 C  is an exemplary flowchart illustrating one exemplary embodiment of a control sequence  300  for the relays  56 ,  60 ,  62 ,  64 ,  66 ,  68  as shown in  FIGS.  2 C and  2 D  of the exemplary embodiment of a topology  50  for a HV architecture for providing electrical power to an electrical load  52  in a vehicle according to the present disclosure. As seen therein, and with continuing reference to  FIGS.  1 B,  2 C, and  2 D , after start  302 , the controller  70  may perform a status check  304  of the relays  56 ,  60 ,  62 ,  64 ,  66 ,  68  to determine  306  if any one or more of the relays  56 ,  60 ,  62 ,  64 ,  66 ,  68  is welded (i.e., “stuck closed”). If so, then the controller  70  may enter and/or may control the circuit and/or method to go to a state of HV power OFF  308 , such that no electrical power is provided to the load  52 . If not, then the controller  70  may generate a control signal for controlling the pre-charge relay  68  (Relay C) to a closed position  310  and then check  312  whether the status of the pre-charge relay  68  (Relay C) is “stuck open”. If so, then the controller  70  may enter and/or may control the circuit and/or method to go to the HV power OFF state  308 . 
     Otherwise, if the status of the pre-charge relay  68  (Relay C) is not “stuck open”, then the controller  70  may generate a control signal for controlling the second relay  64  (Relay E) to a closed position  314  and then check  316  whether the status of the third relay  64  (Relay E) is “stuck open”. If so, then the controller  70  may enter and/or may control the circuit and/or method to go to the HV power OFF state  308 . If not, then the controller  70  may generate a control signal for controlling the main negative relay  60  (Relay F) to a closed position  318  and then check  320  whether the status of the main negative relay  60  (Relay F) is “stuck open”. If so, then the controller  70  may enter and/or may control the circuit and/or method to go to the HV power OFF state  308 . If not, a pre-charge operation  322  may begin and the controller  70  may then determine  324  whether a pre-charge timeout has occurred, i.e., whether a selected period of time has expired before a successful pre-charge of the DC link capacitor  52  has been performed. If so, then the controller  70  may enter and/or may control the circuit and/or method to go to the HV power OFF state  308 . 
     Alternatively, if the controller  70  determines  324  that a pre-charge timeout has not occurred, then the controller  70  may generate a control signal for controlling the main positive relay  56  (Relay B) to a closed position  326  and generate a control signal for controlling the pre-charge relay  68  (Relay C) to an open position  328 . The controller  70  may then check  330  whether the status of the main positive relay  56  (Relay B) is “stuck open”. If so, then the controller  70  may enter and/or may control the circuit and/or method to go to the HV power OFF  308  state. If not, the controller  70  may then determine  332  if a parallel connection of the first and second voltage sources  54   a ,  54   b  to the load  52  should be fulfilled. If not, then the controller  70  may enter and/or may control the circuit and/or method to go to a HV power ON state  334 , such that only the first voltage source  54   a  is connected to and provides electrical power to the load  52  (see  FIG.  2 C ). 
     Otherwise, if the controller  70  determines  332  that a parallel connection of the first and second voltage sources  54   a ,  54   b  to the load  52  should be fulfilled, then the controller  70  may generate a control signal for controlling the third relay  66  (Relay D) to a closed position  336 . The controller  70  may then check  338  whether the status of the third relay  66  (Relay D) is “stuck open”. If so, then the controller  70  may enter and/or may control the circuit and/or method to go to the HV power OFF state  308 . If not, then the controller  70  may enter and/or may control the circuit and/or method to go to the HV power ON state  334 , such that both the first and second voltage sources  54   a ,  54   b  are connected to and provide electrical power to the load  52 , wherein the first and second voltage sources  54   a ,  54   b  are connected in parallel (see  FIG.  2 D ). 
     Referring now to  FIGS.  1 A- 1 B,  2 A- 2 D, and  3 A- 3 C , the present disclosure describes a circuit for providing multi-mode electrical power to a load  52  in a vehicle. The circuit may comprise a first voltage source  54   a  having a positive side and a negative side, and a second voltage source  54   b  having a positive side and a negative side. The circuit may further comprise a main positive relay  56  having a first side and a second side, wherein the second side of the main positive relay  56  may be connected to a first side of the load  52 . The circuit may also comprise a main negative relay  60  having a first side and a second side, wherein the second side of the main negative relay  60  may be connected to a second side of the load  52 . 
     The circuit may further comprise a first relay  62  operable between an open position and a closed position, the first relay  62  having a first side and a second side, the first side of the first relay  62  connected to the positive side of the first voltage source  54   a , and the second side of the first relay  62  connected to the negative side of the second voltage source  54   b . The circuit may also comprise a second relay  64  operable between an open position and a closed position, the second relay  64  having a first side and a second side, the first side of the second relay  64  connected to the positive side of the first voltage source  54   a , and the second side of the second relay  64  connected to the positive side of the second voltage source  54   b  and the first side of the main positive relay  56 . The circuit may further comprise a third relay  66  operable between an open position and a closed position, the third relay  66  having a first side and a second side, the first side of the third relay  66  connected to the negative side of the second voltage source  54   b , and the second side of the third relay  66  connected to the first side of the main negative relay  60 . Accordingly, electrical power may be provided from the first voltage source  54   a  and/or the second voltage source  54   b  to the vehicle load  52  according to one of a plurality of operating modes based on the open or closed positions of the first relay  62 , the second relay  64 , and the third relay  66 . 
     In that regard, in a first operating mode, the first relay  62  may be closed, the second relay  64  may be open, and the third relay  66  may be open to thereby connect the first and second voltage sources  54   a ,  54   b  to the load  52 , wherein the first and second voltage source  54   a ,  54   b  are connected in series. In a second operating mode, the first relay  62  may be open, the second relay  64  may be closed, and the third relay  66  may be open to thereby connect only the first voltage source  54   a  to the load  52 . In a third operating mode, the first relay  62  may be open, the second relay  64  may be open, and the third relay  66  may be closed to thereby connect only the second voltage source  54   b  to the load  52 . In a fourth operating mode, the first relay  62  may be open, the second relay  64  may be closed, and the third relay  66  may be closed to thereby connect the first and second voltage sources  54   a ,  54   b  to the load  52 , wherein the first and second voltage sources  54   a ,  54   b  are connected in parallel. 
     The circuit may further comprise a controller  70  configured to independently control operation of the first relay  62 , the second relay  64 , and the third relay  66  between open and closed positions. Furthermore, the vehicle may be an electric vehicle and the vehicle load  52  may comprise a direct current (DC) link capacitor. Moreover, the circuit may further comprise a pre-charge relay  68  operable between an open position and a closed position, wherein the pre-charge relay  68  may be connected in parallel with the main positive relay  56 . 
     Referring still to  FIGS.  1 A- 1 B,  2 A- 2 D, and  3 A- 3 C , the present disclosure describes a method for providing multi-mode electrical power to a load  52  in a vehicle having a first voltage source  54   a  and a second voltage source  54   b , the load  52  having a first side and a second side, the first voltage source  54   a  having a positive side and a negative side, and the second voltage source  54   b  having a positive side and a negative side. The method may comprise connecting a main positive relay  56  having a first side and second side to the vehicle load  52  by connecting the second side of the main positive relay  56  to the first side of the load  52 . The method may also comprise connecting a main negative relay  60  having a first side and second side to the vehicle load  52  by connecting the second side of the main negative relay  60  to the second side of the load  52 . 
     The method may further comprise connecting a first relay  62  having a first side and a second side to the first voltage source  54   a  and the second voltage source  54   b  by connecting the first side of the first relay  62  to the positive side of the first voltage source  54   a  and connecting the second side of the first relay  62  to the negative side of the second voltage source  54   b . The method may also comprise connecting a second relay  64  having a first side and a second side to the first voltage source  54   a , the second voltage source  54   b , and the main positive relay  56  by connecting the first side of the second relay  64  to the positive side of the first voltage source  54   a  and connecting the second side of the second relay  64  to the positive side of the second voltage source  54   b  and the first side of the main positive relay  56 . The method may further comprise connecting a third relay  66  having a first side and a second side to the second voltage source  54   b  and the main negative relay  60  by connecting the first side of the third relay  66  to the negative side of the second voltage source  54   b  and connecting the second side of the third relay  66  to the first side of the main negative relay  60 . 
     The method may also comprise providing electrical power from the first voltage source  54   a  and/or the second voltage  54   b  source to the vehicle load  52  according to one of a plurality of operating modes by opening or closing each of the first relay  62 , the second relay  64 , and the third relay  66 . In that regard, as previously described, each of the first relay  62 , second relay  64 , and third relay  66  may be independently operable between an open position and a closed position. 
     The plurality of operating modes may include a first operating mode and providing electrical power according to the first operating mode may comprise closing the first relay  62 , opening the second relay  64 , and opening the third relay  66  to thereby connect the first and second voltage sources  54   a ,  54   b  to the vehicle load  52 , wherein the first and second voltage source  54   a ,  54   b  are connected in series. The plurality of operating modes may also include a second operating mode and providing electrical power according to the second operating mode may comprise opening the first relay  62 , closing the second relay  64 , and opening the third relay  66  to thereby connect only the first voltage source  54   a  to the vehicle load  52 . The plurality of operating modes may also include a third operating mode and providing electrical power according to the third operating mode may comprise opening the first relay  62 , opening the second relay  64 , and closing the third relay  66  to thereby connect only the second voltage source  54   b  to the vehicle load  52 . The plurality of operating modes may also include a fourth operating mode and providing electrical power according to the fourth operating mode may comprise opening the first relay  62 , closing the second relay  64 , and closing the third relay  66  to thereby connect the first and second voltage sources  54   a ,  54   b  to the vehicle load  52 , wherein the first and second voltage sources  54   a ,  54   b  are connected in parallel. 
     The vehicle may comprise an electric vehicle and the vehicle load  52  may comprise a direct current (DC) link capacitor. The method may further comprise connecting a pre-charge relay  68  operable between an open position and a closed position in parallel with the main positive relay  56 , and closing the pre-charge relay  68  before opening or closing any of the first relay  62 , the second relay  64 , and/or the third relay  66 . 
     Still referring still to  FIGS.  1 A- 1 B,  2 A- 2 D, and  3 A- 3 C , the present disclosure describes a non-transitory computer readable storage medium having stored computer executable instructions for providing multi-mode electrical power to a load  52  in a vehicle, the vehicle comprising (i) a first voltage source  54   a  having a positive side and a negative side, (ii) a second voltage source  54   b  having a positive side and a negative side, (iii) a main positive relay  56  having a first side and a second side, the second side of the main positive relay  56  connected to a first side of the load  52 , (iv) a main negative relay  60  having a first side and a second side, the second side of the main negative relay  60  connected to a second side of the load  52 , (v) a first relay  62  operable between an open position and a closed position, the first relay  62  having a first side and a second side, the first side of the first relay  62  connected to the positive side of the first voltage source  54   a , and the second side of the first relay  62  connected to the negative side of the second voltage source  54   b , (vi) a second relay  64  operable between an open position and a closed position, the second relay  64  having a first side and a second side, the first side of the second relay  64  connected to the positive side of the first voltage source  54   a , and the second side of the second relay  64  connected to the positive side of the second voltage source  54   b  and the first side of the main positive relay  56 , (vii) a third relay  66  operable between an open position and a closed position, the third relay  66  having a first side and a second side, the first side of the third relay  66  connected to the negative side of the second voltage source  54   b , and the second side of the third relay  66  connected to the first side of the main negative relay  60 , and (viii) a controller  70  configured to independently control operation of the first relay  62 , the second relay  64 , and the third relay  66  between open and closed positions. 
     The computer executable instructions may be configured to cause the controller  70  to provide electrical power from the first voltage source  54   a  and/or the second voltage source  54   b  to the vehicle load  52  according to one of a plurality of operating modes based on the open or closed positions of the first relay  62 , the second relay  64 , and the third  66  relay. In that regard, the plurality of operating modes may include a first operating mode and, to provide electrical power according to the first operating mode, the computer executable instructions may be configured to cause the controller  70  to close the first relay  62 , open the second relay  64 , and open the third relay  66  to thereby connect the first and second voltage sources  54   a ,  54   b  to the vehicle load  52 , wherein the first and second voltage source  54   a ,  54   b  are connected in series. The plurality of operating modes may include a second operating mode and, to provide electrical power according to the second operating mode, the computer executable instructions may be configured to cause the controller  70  to open the first relay  62 , close the second relay  64 , and open the third relay  66  to thereby connect only the first voltage source  54   a  to the vehicle load  52 . The plurality of operating modes may also include a third operating mode and, to provide electrical power according to the third operating mode, the computer executable instructions are configured to cause the controller  70  to open the first relay  62 , open the second relay  64 , and close the third relay  66  to thereby connect only the second voltage source  54   b  to the vehicle load  52 . The plurality of operating modes may further include a fourth operating mode and, to provide electrical power according to the fourth operating mode, the computer executable instructions are configured to cause the controller  70  to open the first relay  62 , close the second relay  64 , and close the third relay  66  to thereby connect the first and second voltage sources  54   a ,  54   b  to the vehicle load  52 , wherein the first and second voltage sources  54   a ,  54   b  are connected in parallel. 
     The vehicle may comprise an electric vehicle and the vehicle load  52  may comprise a direct current (DC) link capacitor. A pre-charge relay  68  operable between an open position and a closed position may be connected in parallel with the main positive relay  56 , and the computer executable instructions may be configured to cause the controller  70  to close the pre-charge relay  68  before opening or closing any of the first relay  62 , the second relay  64 , and/or the third relay  66 . As previously described, the computer executable instructions described herein may be stored in or on a computer readable storage medium which may comprise any known type of storage medium or device and may be part of or associated with the controller  70 . 
     The present disclosure thus describes an improved circuit and method for providing multi-mode electrical power to an electrical load in a vehicle. The improved circuit and method of the present disclosure provide a topology of a HV architecture for an electric vehicle that reduces the number of components needed. For example, topology  50  shown in  FIG.  1 B  utilizes only a single pre-charge relay  68  and associated pre-charge resistor, whereas topology  10  shown in  FIG.  1 A  utilizes two pre-charge relays  16   a ,  16   b  and two associated pre-charge resistors. The improved circuit and method of the present disclosure thereby reduce both cost and the number of possible failure points associated therewith. The improved circuit and method also provide a simplified and/or improved relay control sequence for detecting the status of relays in a HV architecture and providing multiple modes of power to a vehicle electrical load. For example, topology  50  advantageously implements a multi-mode (e.g., 800 V/400 V) compatible HV architecture. 
     As is readily apparent from the foregoing, various non-limiting exemplary embodiments of a circuit and method for providing multi-mode electrical power to an electrical load in a vehicle have been described. While various embodiments have been illustrated and described herein, they are non-limiting and exemplary only and it is not intended that these embodiments illustrate and describe all those possible. Instead, the words used herein are words of description rather than limitation, and it is understood that various changes may be made to these embodiments without departing from the spirit and scope of the following claims.