Electrical systems encompassing multiple battery chemistries and vehicle

Abstract

Electrical system (12), comprising: comprising a battery pack assembly (16): a first cell set (26) with a first plurality of energy storage cells (28) containing a first battery chemistry (30); and a second set of cells (32) with a second plurality of energy storage cells (34) containing a second battery chemistry (38) that differs from the first battery chemistry (30); one or more switches (40, 42) configured to selectively connect the first cell set (26) and the second cell set (32) in series with battery terminals (46) for an electrical connection between them; a DC-DC converter (50) connected to and configured with the first cell set (26) and the second cell set (32) to provide dynamic power distribution between the first and second cell sets (32); and a control unit (18) that controls and is configured for the one or more switches (40, 42) and the DC-DC converter (50): to determine an operating strategy for the battery pack assembly (16); and to bring the first cell set (26), the second cell set (26) or both the first and the second cell set (26, 32) into electrical contact with the battery terminals (46) depending on the operating strategy of the battery pack assembly (16); wherein the operating strategy includes a charging strategy for a relatively high energy state of charge (SOC) for direct current rapid charging (DCFC) when the second cell set (32) has an SOC at or above a predetermined SOC threshold, wherein the charging strategy for a relatively high energy SOC includes DCFC of the second cell set (32) towards a nearly fully charged, predetermined SOC threshold, while the DC-DC converter (50) distributes energy to the first cell set (26), and wherein, When the second cell set (32) reaches the almost fully charged, predetermined SOC threshold, the first cell set (26) undergoes DCFC towards a fully charged SOC, while the DC-DC converter (50) distributes energy to the second cell set (32) to charge both the first and second cell sets (26, 32) towards the full SOC.

Description

[0001] The present description relates to energy or power storage and transfer, and in particular to electrical systems comprising a battery pack assembly with multiple battery chemistries, and methods for controlling the operation of such systems.

[0002] Electrified propulsion systems of motor vehicles and other mobile electrical systems comprise an electrical storage and transmission system configured to supply energy to one or more electric motors to generate drive torque. For example, an electric drive motor may be connected to the wheels of an electric vehicle, with the generated output torque being transferred to the road wheels to propel the electric vehicle along the roadway.

[0003] There is a wide variety of rechargeable energy storage systems (RESSs) for providing electrical power to a traction motor or other output device capable of converting electrical energy into mechanical energy to propel, drive, or otherwise guide a vehicle. During use, a RESS may experience performance degradation, reduced efficiency, slower charging and discharging rates, reduced capacity, and other potential performance-limiting effects.

[0004] DE 10 2018 205 412 A1 describes a method for adjusting the operating voltage of a battery device for a motor vehicle, in which a first operating voltage is provided at a first voltage tap of the battery device and a second operating voltage different from the first operating voltage is provided at a second voltage tap of the battery device, wherein the first operating voltage is provided by a first battery unit of the battery device and a second battery unit of the battery device connected in series with the first battery unit and the second operating voltage is provided only by the first battery unit, wherein energy is transferred between the first battery unit with a first nominal voltage and the second battery unit with a second nominal voltage different from the first nominal voltage for adjusting the operating voltage.

[0005] It can be seen as a task to identify systems and vehicles that can improve the performance of such systems.

[0006] The problem is solved by an electrical system according to claim 1 and a vehicle according to claim 9. Furthermore, an exemplary method for operating the electrical system according to the invention is described.

[0007] An electrical system according to the invention is described. The electrical system comprises a battery pack assembly. The battery pack assembly includes a first cell set with a first plurality of energy storage cells containing a first battery chemistry. A second cell set has a second plurality of energy storage cells containing a second battery chemistry that differs from the first battery chemistry. One or more switches are configured to selectively connect the first cell set and the second cell set in series via battery terminals for an electrical connection between them. A DC-DC converter is connected to the first cell set and the second cell set and configured to provide dynamic energy distribution between the first and second cell sets.The electrical system further includes a control unit that controls the one or more switches and the DC-DC converter. The control unit is configured to determine an operating strategy for the battery pack assembly. The control unit is further configured to electrically connect the first cell set, the second cell set, or both the first and second cell sets to the battery terminals in response to the battery pack assembly's operating strategy. The operating strategy includes a charging strategy for a relatively high state of charge (SOC) for direct current fast charging (DCFC) when the second cell set has an SOC at or above a predetermined SOC threshold.The charging strategy for a relatively high state of charge (SOC) involves DCFC charging the second cell set towards a near-full charge, predetermined SOC threshold, while the DC-DC converter distributes energy to the first cell set. When the second cell set reaches the near-full charge, predetermined SOC threshold, DCFC is then performed on the first cell set towards a full charge, while the DC-DC converter distributes energy to the second cell set to charge both the first and second cell sets towards a full SOC.

[0008] In some embodiments, the first battery chemistry comprises a high energy density battery chemistry, and the second battery chemistry comprises a high charge and discharge rate battery chemistry.

[0009] In some embodiments, the high-energy-density battery chemistry comprises a lithium-ion battery chemistry that includes a cathode containing nickel, cobalt, and manganese (NCM battery chemistry). The high-charge-discharge-rate battery chemistry comprises a sodium-ion battery chemistry (sodium battery chemistry).

[0010] In some embodiments, the one or more switches comprise a first switch and a second switch, which are positionally controlled by the control unit and configured for electrical connection to the first and second cell sets. The first switch has a first switch-A position and a second switch-A position, and the second switch has a first switch-B position and a second switch-B position. When the control unit positions the first switch in the first switch-A position and the second switch in the first switch-B position, the first cell set is electrically connected to the battery terminals, while the second cell set is disconnected from the battery terminals.When the control unit positions the first switch in the first switch-A position and the second switch in the second switch-B position, the first and second cell sets are electrically connected in series to the battery terminals. When the control unit positions the first switch in the second switch-A position and the second switch in the second switch-B position, the second cell set is electrically connected to the battery terminals, while the first cell set is disconnected from the battery terminals.

[0011] In some embodiments, the first switch also has a Switch A Disconnect position and the second switch also has a Switch B Disconnect position. When the control unit positions the first switch in the Switch A Disconnect position and the second switch in the Switch B Disconnect position, the battery pack assembly is disconnected from the battery terminals.

[0012] In some embodiments, the one or more switches comprise a first switch and a second switch, which are positionally controlled by the control unit and configured for electrical connection to the first cell set. The first switch has a first switch-A position and a second switch-A position, and the second switch has a first switch-B position and a switch-B disconnect position. When the control unit positions the first switch in the first switch-A position and the second switch in the switch-B disconnect position, the first cell set and the second cell set are in series and electrically connected to battery terminals.When the control unit positions the first switch in the second switch-A position and the second switch in the first switch-B position, the first set of cells is in parallel and connected to the second set of cells to establish an electrical connection with the battery terminals.

[0013] In some embodiments, the predetermined SOC threshold is around 25% to around 35%, and the almost fully charged predetermined SOC threshold is around 94% to around 98%.

[0014] In some embodiments, the operating strategy includes a charging strategy for a relatively low energy state of charge (SOC) when the second cell set has a SOC at or below a predetermined SOC threshold of near zero. The charging strategy for a relatively low energy SOC involves DCFC of the second cell set towards a nearly fully charged, predetermined SOC threshold, while the DC-DC converter distributes energy to the first cell set. When the second cell set reaches the nearly fully charged, predetermined SOC threshold, DCFC is then performed on the first cell set towards a fully charged SOC, while the DC-DC converter distributes energy to the second cell set to charge both the first and second cell sets towards a fully charged SOC.Alternatively, the first and second cell sets are charged simultaneously in the direction of the fully charged SOC without DCFC operation.

[0015] In some embodiments, the predetermined SOC threshold is at approximately 0% to approximately 10% when almost zero is reached, and the predetermined SOC threshold when almost fully charged is at approximately 94% to approximately 98%.

[0016] In some embodiments, the operating strategy includes a discharge strategy for a relatively high state of charge (SOC) when the second cell set has a SOC above a predetermined SOC threshold. The discharge strategy for a relatively high SOC involves discharging both the first and second cell sets while the DC-DC converter distributes energy from the second cell set to the first cell set until the second cell set is at or below the predetermined SOC threshold. When the second cell set is at or below the predetermined SOC threshold, both the first and second cell sets are discharged while the DC-DC converter distributes energy from the first cell set to the second cell set to fully discharge both.

[0017] In some embodiments, the specified SOC threshold is between approximately 25% and approximately 35%.

[0018] In some embodiments, the operating strategy includes a relatively low-temperature discharge strategy when the battery pack assembly is at a predetermined low-temperature threshold. The relatively low-temperature discharge strategy involves discharging the second cell set while the first cell set is disconnected from the battery terminals and the DC-DC converter distributes power to heat the first cell set to a temperature above the predetermined low-temperature threshold. If the battery pack assembly is at or above a temperature above the predetermined low-temperature threshold, the first and second cell sets are discharged simultaneously.

[0019] In some embodiments, the specified low temperature threshold is between approximately -35 °C and approximately -20 °C.

[0020] In some embodiments, the operating strategy includes a discharge strategy for a driving cycle with a relatively low DC voltage state, which includes discharging the first cell set while the second cell set is disconnected from the battery terminals, or discharging the second cell set while the first cell set is disconnected from the battery terminals.

[0021] In some embodiments, the operating strategy includes a discharge strategy for a driving cycle with a relatively high DC voltage state, which includes discharging the first and second cell sets.

[0022] An exemplary method for operating the electrical system is described. The method includes determining an operating strategy for a battery pack assembly. The battery pack assembly comprises a first cell set with a first plurality of energy storage cells containing a first battery chemistry, and a second cell set with a second plurality of energy storage cells containing a second battery chemistry that differs from the first battery chemistry. The method further includes arranging the first cell set, the second cell set, or both the first and second cell sets in series and electrically connected to battery terminals in response to the operating strategy of the battery pack assembly. Optionally, a dynamic energy distribution between the first and second cell sets is provided in response to the operating strategy of the battery pack assembly.

[0023] A vehicle according to the invention is described. The vehicle comprises an output device and the electrical system according to the invention. The electrical system is configured to supply electrical energy to the output device. The system includes the battery terminals, which are configured to communicate electrically with the output device to discharge the battery pack assembly and power the vehicle, and independently to communicate electrically with a charger to charge the battery pack assembly.

[0024] In some embodiments, the operating strategy includes a charging strategy. The charging strategy includes DCFC of the second cell set while the DC-DC converter distributes energy to the first cell set, or DCFC of the first cell set while the DC-DC converter distributes energy to the second cell set, or simultaneous charging of the first and second cell sets towards a fully charged state of charge (SOC) without DCFC operation.

[0025] In some embodiments, the operating strategy includes a discharge strategy. The discharge strategy optionally includes distributing energy between the first and second cell sets via the DC-DC converter and discharging the first cell set to power the vehicle while the second cell set is disconnected from the battery terminals, or discharging the second cell set to power the vehicle while the first cell set is disconnected from the battery terminals, or discharging both the first and second cell sets to power the vehicle. Fig. Figure 1 shows a schematic view of a vehicle comprising an electrical system and an output device. Fig. Figure 2 shows a schematic view of part of an electrical system comprising a battery pack assembly, switches and a DC-DC converter. Fig. 3A is a graphical representation of an operating strategy for direct current rapid charging (DCFC) of an electrical system in accordance with. Fig. Figure 3B is a graphical representation of an operating strategy for the DCFC of an electrical system. Fig. 3C is a graphical representation of a comparison of the fast charging performance of two different charging scenarios of an electrical system. Fig. Figure 4 is a graphical representation of an operating strategy for a discharge strategy of an electrical system. Fig. Figure 5 shows a schematic view of part of an electrical system comprising a battery pack assembly, switches and a DC-DC converter.

[0026] In the drawings, identical reference numerals refer to the same or similar components in the different illustrations. Fig. Figure 1 illustrates a vehicle 10 comprising an electrical system 12 and an output device 14 according to an exemplary embodiment. As shown, the vehicle 10 is a terrestrial electric vehicle (EV).

[0027] Fig. Figure 2 shows a schematic view of part of the electrical system 12 in accordance with an exemplary embodiment. As shown in the Fig. As shown in Figures 1-2, the electrical system 12 comprises a rechargeable energy storage system (RESS), referred to here as the "battery pack assembly" 16, and a control unit 18. The battery pack assembly 16, the control unit 18, and the output device 14 are installed in the vehicle and are interconnected. As explained in more detail below, the battery pack assembly 16 is configured to generate and store electrical energy through electrochemical reactions in order to supply the electrical energy to the output device 14 to power the vehicle 10 during use, for example, to transmit torque to the wheels 20 to move the vehicle 10 along a road 22. Furthermore, and as shown, the battery pack assembly 16 is rechargeable via an external charger 24, for example, at a charging station or the like.

[0028] The control unit 18 is programmable and may include a central processing unit (CPU) that controls various functions of the vehicle 10, including the output device 14 and / or the battery pack assembly 16. In one exemplary embodiment, the control unit 18 comprises a processor and tangible, non-transferable memory containing programmed instructions for the operation of the vehicle 10, including the output device 14 and the battery pack assembly 16. In one or more embodiments, the control unit 18 includes a battery management system (BMS) that controls or otherwise manages the operation of the battery pack assembly 16. The memory may be a suitable writable medium involved in providing computer-readable data or process instructions.Such a describable medium can take many forms, including, but not limited to, non-volatile and volatile media.

[0029] The non-volatile media for the control unit 16 can include, for example, optical or magnetic disks and other permanent storage media. The volatile media can include, for example, dynamic random access memory (DRAM), which can represent main memory. Such instructions can be transmitted via one or more transmission media, including coaxial cable, copper wire, and fiber optic cable, including the wires comprising a system bus connected to a computer processor, or via a wireless connection.

[0030] The memory of the control unit 18 can also include a flexible disk, a hard disk, a magnetic tape, another magnetic medium, a CD-ROM, a DVD, another optical medium, etc. The control unit 18 can be configured or equipped with other necessary computer hardware, such as a high-speed clock, required analog-to-digital (A / D) and / or digital-to-analog (D / A) circuits, input / output (I / O) circuits and devices, and suitable signal conditioning and / or buffering circuits.Algorithms required by or accessible to the control unit 18, including but not limited to prediction algorithms, algorithms for determining different operating strategies for controlling the operation of the battery pack assembly 16, or similar, can be stored in memory and executed automatically to provide the required functionality of the vehicle 10, including the output device 14 and the battery pack assembly 16.

[0031] As in Fig. As shown in Figure 2, the battery pack assembly 16 comprises a cell set 26 (e.g., the first cell set) with a plurality of energy storage cells 28 and a cell set 32 ​​(e.g., the second cell set) with a plurality of energy storage cells 34. As explained in more detail below, the energy storage cells 28 comprise or contain a battery chemistry 30, and the energy storage cells 34 comprise or contain a battery chemistry 38 that differs from the battery chemistry 30.

[0032] The electrical system 12 further comprises switches 40 and 42, which are arranged along the bus 44 that is electrically connected to the cell sets 26 and 32. Switches 40 and 42 are configured to selectively connect the cell sets 26 and 32 in series with the battery terminals 46, which are electrically connected either to the output device 14 (load) or the charger 24, depending on whether the cell sets 26 and 32 are being discharged or charged, respectively, to establish an electrical connection between them. As will be explained in more detail below, a DC-DC converter 50 is arranged along the bus 48 and connected to the cell sets 26 and 32 to provide dynamic power distribution (e.g., power distribution or transfer from one cell set 26 or 32 to the other 32 or 26) between the cell sets 26 and 32.

[0033] In an exemplary embodiment, the control unit 18 controls the switches 40 and 42 and the DC-DC converter 50. Furthermore, the control unit 18 is ready to determine an operating strategy for the battery pack assembly 16 and to connect the cell set 26, the second cell set 32, or both cell sets 26 and 32 to the battery terminals 46, depending on the operating strategy of the battery pack assembly 16.

[0034] In an exemplary embodiment, the battery chemistry 30 of the energy storage cells 28 is or otherwise includes a high-energy-density battery chemistry, while the battery chemistry 38 of the energy storage cells 34 is or otherwise includes a high-charge-discharge-rate battery chemistry. In an exemplary embodiment, the high-energy-density battery chemistry is or includes a lithium-ion battery chemistry comprising a cathode consisting of nickel, cobalt, and manganese (NCM battery chemistry). In an exemplary embodiment, the high-charge-discharge-rate battery chemistry comprises a sodium-ion battery chemistry (sodium battery chemistry).

[0035] Switches 40 and 42 are positionally controlled by control unit 18. Switches 40 and 42 are configured for electrical connection to cell sets 26 and 32. As shown, switch 40 has a first switch-A position 52 and a second switch-A position 54. Similarly, switch 42 has a first switch-B position 56 and a second switch-B position 58. When control unit 18 positions switch 40 in the first switch-A position 52 and switch 42 in the first switch-B position 56, cell set 26 is electrically connected to battery terminals 46, while cell set 32 ​​is disconnected from battery terminals 46. When the control unit 18 positions the switch 40 in the first switch-A position 52 and the switch 42 in the second switch-B position 58, the cell set 26 and the cell set 32 ​​are connected in series and are electrically connected to the battery terminals 46.When the control unit 18 positions the switch 40 in the second switch-A position 54 and the switch 42 in the second switch-B position 58, the cell set 32 ​​is also in electrical connection with the battery terminals 46, while the cell set 26 is disconnected from the battery terminals 46.

[0036] In an exemplary embodiment, the electrical system 10 is configured to disconnect the connection between the battery pack assembly 16 and the battery terminals 46. As shown, the switch 40 also has a switch-A disconnect position 60, and the switch 42 also has a switch-B disconnect position 62. When the control unit 18 positions the switch 40 in the switch-A disconnect position 60 and the switch 42 in the switch-B disconnect position 62, the battery pack assembly 16 is disconnected from the battery terminals 46 in an exemplary embodiment.

[0037] In an exemplary embodiment, the illustrated electrical system 12, which incorporates various battery chemistries, provides improved efficiency, increased charging and discharging power, greater capacity, and enhanced performance based on different operating strategies that leverage the advantages of each of the different battery chemistries under various scenarios. Some non-limiting examples of different operating strategies for the electrical system 12 are given below.

[0038] Fig. Figure 3A is a graphical representation of an operating strategy for direct current rapid charging (DCFC) of the electrical system 12, where the X-axis represents time (T) and the Y-axis represents the state of charge (SOC) according to an exemplary embodiment. With reference to Fig. In an exemplary embodiment, the operating strategy described in Section 1-3A comprises a charging strategy for a relatively high state of charge (SOC) for the DCFC of a battery pack assembly 16, provided that the battery pack assembly 16, and in particular the cell set 32, has a relatively high SOC at or above a predetermined SOC threshold. In an exemplary embodiment, the predetermined threshold is between approximately 25% and approximately 35%, for example, approximately 30%.

[0039] In one or more embodiments, the charging strategy for a relatively high energy state of charge (SOC) includes charging the DCF of cell set 32 ​​towards a nearly fully charged, predetermined SOC threshold, while the DC-DC converter 50 distributes energy from cell set 32 ​​to cell set 26. In an exemplary embodiment, the predetermined threshold for the nearly fully charged SOC is between approximately 94% and approximately 98%, for example, approximately 96%. In one or more embodiments, when cell set 32 ​​reaches the predetermined threshold for the nearly fully charged SOC, cell set 26 is charged to a fully charged SOC (e.g., approximately 100%), while the DC-DC converter 50 distributes energy from cell set 26 to cell set 32 ​​to charge both cell set 26 and cell set 32 ​​to a fully charged SOC.

[0040] Fig. Figure 3B is a graphical representation of an operating strategy for the DCFC of the electrical system 12, in which the X-axis represents time (T) and the Y-axis represents the state of charge (SOC) in accordance with an exemplary embodiment. With reference to the Fig. In an exemplary embodiment, the operating strategy described in sections 1-2 and 3B includes a charging strategy for a relatively low state of charge (SOC) when the battery pack assembly 16, and in particular when the cell set 32 ​​(or both cell sets 26 and 32), has a SOC at or below a predetermined SOC threshold of near zero. In an exemplary embodiment, the predetermined SOC threshold of near zero is approximately 0% to approximately 10%, for example, approximately 0%.

[0041] In one or more embodiments, the charging strategy for a relatively low energy state of charge (SOC) includes the DC-DC converter of cell set 32 ​​charging towards a predetermined threshold for a nearly fully charged SOC, while the DC-DC converter 50 distributes energy to cell set 26. In one or more embodiments, when cell set 32 ​​reaches the predetermined threshold for a nearly fully charged SOC, cell set 26 is charged with DC current to a fully charged SOC, while the DC-DC converter 50 distributes energy from cell set 26 to cell set 32 ​​to charge both cell set 26 and cell set 32 ​​towards a fully charged SOC (e.g., about 100%). In an exemplary embodiment, the predetermined threshold for a nearly fully charged SOC is between about 94% and about 98%, e.g., about 96%.Alternatively, cell sets 26 and 32 can be charged simultaneously in the direction of the fully charged SOC, for example without DCFC operation.

[0042] Fig. Figure 3C is a graphical representation comparing the fast-charging performance of two different charging scenarios of an electrical system, where the Y-axis represents the driving miles (M) based on the charging scenario(s) according to an exemplary embodiment. Bar 64 shows the simultaneous charging of cell sets 26 and 32 (containing, for example, the NCM battery chemistry and the sodium battery chemistry, respectively), for example, for 10 minutes of DCFC charging. Bar 66 represents a 10-minute DCFC charge of cell set 32 ​​alone (containing, for example, the sodium battery chemistry). As shown, bar 66 corresponds to 1.9 times (190 miles versus 100 miles) bar 64 for the resulting driving distance with the same duration (e.g., 10 minutes) and the same type of charging (e.g., DCFC).

[0043] Fig. Figure 4 is a graphical representation of an operating strategy for a discharge strategy of the electrical system 12, where the X-axis represents time (T) and the Y-axis represents the state of charge (SOC) according to an exemplary embodiment. Referring to the Fig. In an exemplary embodiment, the operating strategy described in sections 1-2 and 4 comprises a discharge strategy with a relatively high state of charge (SOC) for when the battery pack assembly 16, and in particular the cell set 32 ​​(or both cell sets 26 and 32), has a SOC (e.g., from about 40% to about 100%, e.g., almost fully charged) above a predetermined SOC threshold. In an exemplary embodiment, the predetermined SOC threshold is about 25% to about 35%, e.g., about 30%. In an exemplary embodiment, the discharge strategy for a relatively high SOC comprises discharging the cell sets 26 and 32 while the DC-DC converter 50 distributes energy from cell set 32 ​​to cell set 26 until cell set 32 ​​reaches or falls below the predetermined SOC threshold.When cell set 32 ​​reaches or falls below the predetermined SOC threshold, cell sets 26 and 32 are discharged, while the DC-DC converter 50 distributes energy from cell set 26 to cell set 32 ​​to fully discharge cell sets 26 and 32.

[0044] Referring again to the Fig. 1-2, the operating strategy in an exemplary embodiment includes a discharge strategy at a relatively low temperature when the battery pack assembly reaches a predetermined low-temperature threshold. In an exemplary embodiment, the predetermined low-temperature threshold is approximately -20 °C or less, for example, from approximately -35 °C to approximately -20 °C. In one or more embodiments, the discharge strategy at a relatively low temperature includes discharging cell set 32 ​​while cell set 26 is disconnected from the battery terminals and the DC-DC converter 50 distributes energy to heat cell set 26 to a temperature above the predetermined low-temperature threshold. When the battery pack assembly 16 reaches a temperature (e.g., approximately 0 °C or higher) above the predetermined low-temperature threshold, cell sets 26 and 32 are discharged simultaneously.

[0045] In one exemplary embodiment, the operating strategy includes a driving cycle discharge strategy at relatively low DC voltage, which is used, for example, during city driving. The driving cycle discharge strategy at relatively low voltage includes discharging cell set 26 while cell set 32 ​​is disconnected from the battery terminals 46. In an alternative embodiment, the driving cycle discharge strategy at relatively low voltage includes discharging cell set 32 ​​while cell set 26 is disconnected from the battery terminals 46.

[0046] In one exemplary embodiment, the operating strategy includes a driving cycle discharge strategy at relatively high DC voltage, which is used, for example, during highway driving. The driving cycle discharge strategy at relatively high DC voltage involves the simultaneous discharge of cell sets 26 and 32.

[0047] Fig. Figure 5 shows a schematic view of part of an electrical system 112, comprising a battery pack assembly 116, switches 160 and 162, and the DC-DC converter 150 according to an exemplary embodiment. The electrical system 112, including the battery pack assembly 116, the cell sets 126 and 132, the DC-DC converter 150, and the battery terminals 46, is configured similarly to the electrical system 12, including the battery pack assembly 16, the cell sets 26 and 32, the DC-DC converter 50, and the battery terminals 46, as shown in Figure 5. Fig.Figure 2 shows the configuration, except that switches 160 and 162 are arranged for electrical connection with the cell set 126. In an exemplary embodiment, switches 160 and 162 (e.g., positionally controlled) and the DC-DC converter 150 are controlled by the control unit 18 to connect the cell sets 126 and / or 132 to the battery terminals 46, depending on the operating strategy(ies) described above.

[0048] In an exemplary embodiment, switch 160 has a first switch A position 168 and a second switch A position 170, and switch 162 has a first switch B position 172 and a switch B disconnect position 174. When the control unit 18 positions switch 160 in the first switch A position 168 and switch 162 in the switch B disconnect position 174, cell set 126 and cell set 132 are connected in series and are electrically connected to the battery terminals 46. Furthermore, in an exemplary embodiment, when the control unit 18 positions switch 126 in the second switch A position 170 and switch 132 in the first switch B position 172, cell set 126 is connected in parallel and electrically connected to cell set 132 via the battery terminals 46.

[0049] In an exemplary embodiment, connecting cell set 126 in parallel with cell set 132, thereby adjusting the C-rate charging of cell sets 126 and 132, advantageously contributes to improving fast-charging capability. In an exemplary embodiment, connecting cell set 126 in series advantageously ensures that both cell sets 126 and 132 are discharged simultaneously. In an exemplary embodiment, the DC-DC converter 50 can be optional, i.e., it can be omitted for some applications and included for others to enable dynamic energy distribution between cell sets 126 and 132 depending on the operating strategy of the battery pack assembly 116.

Claims

[1] Electrical system (12), comprising: comprising a battery pack assembly (16): a first cell set (26) with a first plurality of energy storage cells (28) containing a first battery chemistry (30); and a second set of cells (32) with a second plurality of energy storage cells (34) containing a second battery chemistry (38) that differs from the first battery chemistry (30); one or more switches (40, 42) configured to selectively connect the first cell set (26) and the second cell set (32) in series with battery terminals (46) for an electrical connection between them; a DC-DC converter (50) connected to and configured with the first cell set (26) and the second cell set (32) to provide dynamic power distribution between the first and second cell sets (32); and a control unit (18) that controls and is configured for the one or more switches (40, 42) and the DC-DC converter (50): to determine an operating strategy for the battery pack assembly (16); and to bring the first cell set (26), the second cell set (26) or both the first and the second cell set (26, 32) into electrical contact with the battery terminals (46) depending on the operating strategy of the battery pack assembly (16); wherein the operating strategy includes a charging strategy for a relatively high energy state of charge (SOC) for direct current rapid charging (DCFC) when the second cell set (32) has an SOC at or above a predetermined SOC threshold, wherein the charging strategy for a relatively high energy SOC includes DCFC of the second cell set (32) towards a nearly fully charged, predetermined SOC threshold, while the DC-DC converter (50) distributes energy to the first cell set (26), and wherein, When the second cell set (32) reaches the almost fully charged, predetermined SOC threshold, the first cell set (26) undergoes DCFC towards a fully charged SOC, while the DC-DC converter (50) distributes energy to the second cell set (32) to charge both the first and second cell sets (26, 32) towards the full SOC. [2] Electrical system (12) according to claim 1, wherein the one or more switches (40, 42) comprise a first switch (40) and a second switch (42) which are positionally controlled by the control unit (18) and are configured for electrical connection with the first and second cell sets (26, 32), wherein the first switch (40) has a first switch-A position (52) and a second switch-A position (54) and the second switch (42) has a first switch-B position (56) and a second switch-B position (58), wherein when the control unit (18) positions the first switch (40) in the first switch-A position (52) and the second switch (42) in the first switch-B position (56), the first cell set (26) is in electrical connection with the battery terminals (46), while the second cell set (32) is disconnected from the battery terminals (46). is, wherebywhen the control unit (18) positions the first switch (40) in the first switch-A position (52) and the second switch (42) in the second switch-B position (58), the first cell set (26) and the second cell set (32) are in series and electrically connected to battery terminals (46), and wherein, when the control unit (18) positions the first switch (40) in the second switch-A position (54) and the second switch (42) in the second switch-B position (58), the second cell set (32) is electrically connected to the battery terminals (46), while the first cell set (26) is disconnected from the battery terminals (46). [3] Electrical system (12) according to claim 2, wherein the first switch (40) further has a switch-A disconnect position (60) and the second switch (42) further has a switch-B disconnect position (62), and wherein when the control unit (18) positions the first switch (40) in the switch-A disconnect position (60) and the second switch (42) in the switch-B disconnect position (62), the battery pack assembly (16) is disconnected from the battery terminals (46). [4] Electrical system (12) according to claim 1, wherein the one or more switches (40, 42) comprise a first switch (40) and a second switch (42) which are positionally controlled by the control unit (18) and are configured for electrical connection with the first cell set (26), wherein the first switch (40) has a first switch-A position (52) and a second switch-A position (54) and the second switch (42) has a first switch-B position (56) and a switch-B disconnect position (62), wherein when the control unit (18) positions the first switch (40) in the first switch-A position (52) and the second switch (42) in the switch-B disconnect position (62), the first cell set (26) and the second cell set (32) are in series in electrical connection with battery terminals (46), and wherein,when the control unit (18) positions the first switch (40) in the second switch-A position (54) and the second switch (42) in the first switch-B position (56), the first cell set (26) is connected in parallel and to the second cell set (32) for an electrical connection to the battery terminals (46). [5] Electrical system (12) according to claim 1, wherein the operating strategy comprises a charging strategy for a relatively low energy SOC when the second cell set (32) has a SOC at or below a predetermined SOC threshold of near zero, wherein the charging strategy for a relatively low energy SOC comprises: DCFC of the second cell set (32) towards a nearly fully charged, predetermined SOC threshold, while the DC-DC converter (50) distributes energy to the first cell set (26), and wherein, when the second cell set (32) reaches the nearly fully charged, predetermined SOC threshold, then the first cell set (26) undergoes DCFC towards a fully charged SOC, while the DC-DC converter (50) distributes energy to the second cell set (32) to charge both the first and second cell sets (26, 32) towards the fully charged SOC; or Simultaneous charging of the first and second cell set (26, 32) towards the fully charged SOC without DCFC operation. [6] Electrical system (12) according to claim 1, wherein the operating strategy comprises a discharge strategy for a relatively high SOC when the second cell set (32) has a SOC above a predetermined SOC threshold, wherein the discharge strategy for a relatively high SOC comprises discharging the first and second cell sets (26, 32) while the DC-DC converter (50) distributes energy from the second cell set (32) to the first cell set (26) until the second cell set (32) is at or below the predetermined SOC threshold, and wherein, when the second cell set (32) is at or below the predetermined SOC threshold, discharging the first and second cell sets (26, 32) while the DC-DC converter (50) distributes energy from the first cell set (26) to the second cell set (32) to completely discharge the first and second cell sets (26, 32). [7] Electrical system (12) according to claim 1, wherein the operating strategy comprises a discharge strategy for a relatively low temperature when the battery pack assembly (16) is at a predetermined low-temperature threshold, wherein the discharge strategy for a relatively low temperature comprises discharging the second cell set (32) while the first cell set (26) is disconnected from the battery terminals (46) and the DC-DC converter (50) distributes energy to heat the first cell set (26) to a temperature above the predetermined low-temperature threshold, and wherein when the battery pack assembly (16) is at or above the temperature above the predetermined low-temperature threshold, the first and second cell sets (26, 32) are discharged simultaneously. [8] Electrical system (12) according to claim 1, wherein the operating strategy comprises a driving cycle discharge strategy at relatively low DC voltage, comprising: Discharging the first set of cells (26) while the second set of cells (32) is disconnected from the battery terminals (46); or Discharging the second set of cells (32) while the first set of cells (26) is disconnected from the battery terminals (46). [9] Vehicle (10), comprising: an output device (14); and the electrical system (12) according to any one of the preceding claims 1 to 8, configured to supply the output device with electrical energy, wherein the electrical system (12) comprises the battery terminals (46) configured to communicate electrically with the output device (14) to discharge the battery pack assembly (16) and to power the vehicle (10), and independently to communicate electrically with a charger (24) to charge the battery pack assembly (16).

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