SYSTEM AND METHOD FOR OPERATING A POWER SOURCE WITH MIXED CHEMICALS

Abstract

An electrical system comprises a high-voltage battery pack assembly with a first cell set containing a first group of energy storage cells and a second cell set containing a second group of energy storage cells, which is connectable to the first cell set. The first cell set includes at least one first battery chemistry cell, and the second cell set includes at least one second battery chemistry cell. At least one switch is electrically connected to either the first or the second cell set. Battery terminals are electrically connected to at least one of the first or second cell sets. A control unit is configured to determine an operating strategy for the high-voltage battery pack assembly and, in response to the operating strategy of the high-voltage battery pack, to electrically connect at least one cell from either the first or the second cell set to the battery terminals.

Description

introduction

[0001] Electrified propulsion systems of motor vehicles and other mobile electrical systems comprise an electrical system configured to supply energy to one or more electric motors to generate drive torque. For example, an electric traction motor may be connected to the wheels of an electric vehicle, with the generated output torque being directed to the wheels to propel the electric vehicle along a roadway. For this purpose, a high-voltage bus of the electric vehicle is connected to a rechargeable energy storage system (RESS), the main component of which is a traction battery pack with a number and configuration of electrochemical battery cells suitable for the application.The connection between the battery pack and the motor is established via an intermediate power inverter module when the electric traction motor is configured as a multi-phase / alternating current (AC) machine. Summary

[0002] An electrical system is disclosed herein. The electrical system includes a high-voltage battery pack assembly having a first cell pack with a first group of energy storage cells and a second cell pack with a second group of energy storage cells connectable to the first cell pack. The first cell pack includes at least one first battery chemistry cell, and the second cell pack includes at least one second battery chemistry cell. At least one switch is in electrical communication with one of the first cell pack and the second cell pack. Battery terminals are in electrical communication with at least one of the first and second cell packs.A controller is configured to determine an operating strategy of the high-voltage battery pack assembly and, in response to the operating strategy of the high-voltage battery pack, to place at least one of the first cell set or the second cell set into electrical communication with the battery terminals.

[0003] Another aspect of the disclosure may be that the controller is configured to isolate the first set of cells from the battery terminals when the operating strategy includes operating the electrical system at a temperature below a predetermined threshold.

[0004] Another aspect of the disclosure may be that the controller is configured to increase an output voltage of the second cell set with a DC-DC converter when the operating strategy includes operating the electrical system at a temperature below a predetermined threshold to heat the first cell set.

[0005] Another aspect of the disclosure may be that the controller is configured to adapt an output voltage of the second cell set to the first cell set with a DC-DC converter when the operating strategy includes operating the electrical system at a temperature below a predetermined threshold and the at least one switch connects the first cell set in parallel to the second cell set.

[0006] Another aspect of the disclosure may be that the operating strategy includes operating the electrical system above a predetermined threshold temperature.

[0007] Another aspect of the disclosure may be that the controller is configured to position the at least one switch such that the first set of cells is connected in parallel with the second set of cells.

[0008] Another aspect of the disclosure may be that the controller is configured to position the at least one switch to isolate the first set of cells from the battery terminals until a second voltage across the second set of cells is reduced to equal a first voltage across the first set of cells.

[0009] Another aspect of the disclosure may be that the controller is configured to use a DC-DC converter to increase an output voltage of the second cell set when the first cell set has an output voltage that is greater than an output voltage of the second cell set.

[0010] Another aspect of the disclosure may be that the controller is configured to disconnect the second cell set from the battery terminals when an output voltage of the first cell set is greater than an output voltage of the second cell set.

[0011] Another aspect of the disclosure may be that the controller is configured to disconnect the first set of cells from the battery terminals to charge the second set of cells when the battery terminals are in electrical communication with a power charging source.

[0012] Another aspect of the disclosure may be that the controller is configured to bypass a DC-DC converter when charging the second set of cells.

[0013] Another aspect of the disclosure may be that the controller is configured to isolate the second set of cells when an output voltage of the second set of cells reaches a predetermined charging threshold, and that the controller is configured to position the at least one switch to isolate the second set of cells and charge the first set of cells, wherein the power charging source is in electrical communication with the battery terminals.

[0014] Another aspect of the disclosure may be that the first cell set comprises a group of lithium iron phosphate cells and at least one sodium ion cell and the second cell set comprises a group of sodium ion cells.

[0015] Another aspect of the disclosure may be that the controller is configured to measure a state of charge of the first set of cells by measuring a voltage across the at least one sodium-ion cell.

[0016] Another aspect of the disclosure may be that the controller is configured to position the at least one switch such that the second set of cells is connected in series with a DC-DC converter.

[0017] Another aspect of the disclosure may be that the first cell set comprises a group of silicon anode cells and the second cell set comprises sodium ion cells, wherein the first cell set and the second cell set are connected to a DC-DC converter.

[0018] Disclosed herein is a method for operating an electrical system. The method includes determining an operating strategy for a high-voltage battery pack assembly. The high-voltage battery pack assembly includes a first cell set and a second cell set connected to the first cell set. The first cell set includes at least a first battery chemistry, and the second cell set includes at least a second battery chemistry. The method also includes placing the first cell set and the second cell set in electrical communication with battery terminals in response to the operating strategy of the high-voltage battery pack.

[0019] A vehicle system is disclosed herein. The vehicle system includes a traction battery forming a high-voltage battery pack assembly having a first cell set and a second cell set connected to the first cell set. The first cell set includes at least one first battery chemistry cell, and the second cell set includes a second battery chemistry cell. A traction motor is in communication with the traction battery. A controller is configured to determine an operating strategy for the high-voltage battery pack assembly. The controller is further configured to place at least one of the first cell set or the second cell set into electrical communication with battery terminals in response to the high-voltage battery pack operating strategy. Short description of the drawings Fig. 1 shows an example of an electrical system configured to charge a high voltage battery pack, wherein the high voltage battery pack is configured to supply power to a low voltage bus. Fig. 2 is a schematic diagram of an exemplary battery pack arrangement. Fig. 3 shows an example of a method for operating the battery pack assembly of Fig. 2. Fig. Figure 4 shows another example of a battery pack arrangement. Fig. 5 shows a method for operating the battery pack assembly of Fig. 4. Fig. Figure 6 shows another example of a battery pack arrangement.

[0020] The accompanying drawings are not necessarily to scale and present a somewhat simplified representation of various preferred features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, positions, and shapes. Details associated with such features will be determined in part by the particular intended application and environment of use. Detailed description

[0021] In the drawings, like reference numerals refer to like or similar components in the different illustrations. Fig. 1 shows an electrical system 12, e.g., an electrified drive system of a motor vehicle 40 having a vehicle body 41 defining a vehicle interior 42. The motor vehicle 40 of Fig. 1 may also include a front trunk (“frunk”) 46 or other compartment that provides the user with access to a charging receptacle REC. The motor vehicle 40 also includes wheels 43 for road travel. The wheels 43 may be driven / powered by the electrical system 12 or may be non-driven / free-wheeling, as described in more detail below.

[0022] The electrical system 12 includes separate high-voltage and low-voltage buses. The high-voltage bus 20-H is in electrical connection with a high-voltage battery pack assembly 13, such as a traction battery, and the low-voltage bus 20-L is in electrical connection with an auxiliary battery (B AUX") 30. At least one on-board charging module (OBCM) 22 includes inputs in communication with the charging receptacle REC as a power converter to convert an alternating current (AC) source from a charging station 48 to direct current (DC) at a receptacle to charge the battery pack assembly 13. At least one auxiliary power module (APM) 21 isolates the high-voltage bus 20-H from the low-voltage bus 20-L with an input in communication with the high-voltage bus 20-H and outputs in communication with the low-voltage bus 20-L to charge the auxiliary battery 30 and operate vehicle accessories such as heated seats, power windows, or navigation systems. The OBCM 22 and the APM 21 are both in communication with an electronic control module 28 in the electrical system 12.

[0023] The electronic control unit 28 may include a computer and / or processor and may include software, hardware, memory, algorithms, connections, etc. for managing and controlling the operation of the motor vehicle 40. As such, a method described below and generally in Fig. 5, may be embodied as a program or algorithm, partially operable on the controller 28. It should be appreciated that the controller 28 may comprise a device capable of analyzing data from the sensors, comparing data, making the necessary decisions to control the operation of the motor vehicle 40, and performing the necessary tasks to control the operation of the motor vehicle 40.

[0024] The controller 28 may be embodied as one or more digital computers or host machines, each including one or more processors, read-only memory (ROM), random access memory (RAM), electrically programmable read-only memory (EPROM), optical drives, magnetic drives, etc., a high-speed clock, analog-to-digital (A / D) circuitry, digital-to-analog (D / A) circuitry, and input / output (I / O) circuitry, I / O devices and communication interfaces, as well as signal conditioning and buffer electronics. The computer-readable memory may include a non-volatile / tangible medium involved in providing data or computer-readable instructions. The memory may be non-volatile or volatile. Non-volatile media may include, for example, optical or magnetic disks and other persistent storage.Example volatile memories may include dynamic random-access memory (DRAM), which may constitute main memory. Other examples of memory embodiments include a flexible disk, hard disk, magnetic tape or other magnetic medium, a CD-ROM, DVD, and / or other optical medium, as well as other possible storage devices such as flash memory.

[0025] The control unit 28 includes a tangible, non-transferable memory in which computer-executable instructions, including one or more algorithms, for controlling the operation of the motor vehicle 40 are recorded. The algorithm(s) in question may, in particular, include an algorithm configured to optimize the energy consumption of the motor vehicle 40.

[0026] In the example shown, features and functions of the power converters, such as the auxiliary power module 21 or the on-board charging modules 22, can be Fig. 1, partially or completely integrated into the structure of the electrical system 12. Furthermore, the present teaching applies to a wide range of mobile and stationary variants of the electrical system 12, including, but not limited to, electrified drive systems of aircraft, ships, rail vehicles, agricultural equipment, transport equipment and other mobile platforms on land, water or in the air, as well as power plants, lifting equipment, conveyor systems and the like. The descriptions of the Fig. The specific vehicle usage scenarios shown in Figure 1 are therefore not limiting and are only illustrative of a possible implementation.

[0027] Furthermore, what the representative electrical system 12 of Fig. 1, the electrical system 12 is characterized by its separate high-voltage and low-voltage buses, designated "20-H" and "20-L," respectively. In embodiments where the electrical system 12 is part of the motor vehicle 40, e.g., an electric vehicle constructed as a battery-powered electric vehicle, a hybrid electric vehicle, or an extended-range electric vehicle, the term "high voltage" may encompass battery voltage capabilities of approximately 300 volts (V) or more. Such voltage levels are suitable for generating drive torque for vehicle propulsion functions and for powering various high-voltage accessories onboard the motor vehicle 40. The term "low voltage," in turn, refers to auxiliary voltage levels of typically 12-50 V.Low voltage lines (not shown) thus connect the low voltage bus 20-L to one or more low voltage accessories located on board the motor vehicle 40, including, but not limited to, lights, radios, infotainment screens, sensors, etc.

[0028] In the exemplary embodiment of Fig. 1, the battery pack assembly 13 is selectively connected to and disconnected from a load via a series of high-voltage contactors 15. The applied load in the illustrated configuration includes a direct current (“DC”) link capacitor (C1), an inverter module (“inverter”) 16 having a plurality of semiconductor switches 17 connected to an electric traction motor (“M”) 18. According to the prior art, inverters such as the one shown in Fig. 1, the inverter 16 comprises a plurality of chips of semiconductor switches 17 as fast-acting ON / OFF switching devices, e.g., insulated gate bipolar transistors (“IGBTs”), metal oxide semiconductor field-effect transistors (“MOSFETs”), thyristors, etc. In a typical three-phase configuration of the electric traction motor 18, the semiconductor switches 17 are turned on or off at predetermined switching intervals to output an alternating current (“AC”) waveform to the electric traction motor 18.

[0029] The Fig. The electric traction motor 18 shown in Figure 1 is connected to a rotatable output member 19, such as a motor shaft and connected gears (not shown). In the drive modes, the inverter 16 is controlled using pulse width modulation (PWM) or other application-appropriate switching control technique to energize the phase windings of the electric traction motor 18. As shown, the electric traction motor 18 is a polyphase alternating current (AC) motor, in this case a three-phase machine. The rotation of the output member 19 ultimately transfers torque (To) to a coupled load, including one or more wheels 43 of the motor vehicle 40.During the discharge / drive modes, the electrical energy stored in individual electrochemical battery cells (not shown) of the high-voltage battery pack assembly 13 is used to drive the rotation of one or more of the wheels 43. Other embodiments of the motor vehicle 40 may use more or fewer wheels 43. Furthermore, some of the wheels 43 may be undriven / freewheeling, e.g., in rear-wheel drive or front-wheel drive configurations, or the wheels 43 may be driven / powered, e.g., in an all-wheel drive or four-wheel drive configuration, without limitation.

[0030] The electrical system 12 of Fig. 1 may also include additional components for powering various systems or functions on board the motor vehicle 40. For example, the illustrated high-voltage battery pack assembly 13 is connected to the APM 21. As such, the APM 21 is operable to reduce a DC voltage level of the high-voltage bus 20-H, e.g., 300 V or more, as mentioned above, to a typical auxiliary voltage level of 12-50 V for the low-voltage bus 20-L. The auxiliary battery 30, such as a 12V / 48V lead-acid or lithium auxiliary battery, may be electrically connected to the APM 21, with the internal switching operation of the APM ensuring that the auxiliary battery 30 remains charged, i.e., that the voltage of the auxiliary battery (V AUX ) is about 12-50V.

[0031] Fig. 2 shows an example of a high-voltage battery pack assembly 13. In the illustrated example, the high-voltage battery pack assembly 13 includes a first plurality of energy storage cells, e.g., a first cell set 50, and a second plurality of energy storage cells, e.g., the second cell set 52. The first cell set 50 is connected to the second cell set 52 in a parallel electrical configuration. The first cell set 50 includes at least one first battery chemistry cell 54 connected in series with at least one second battery chemistry cell 56. The second cell set 52 includes a plurality of second battery chemistry cells 56 connected in series without having the first battery chemistry cells 54.

[0032] In the example shown, the first battery chemistry cells comprise 54 lithium iron phosphate (LFP) cells and the second battery chemistry cells comprise 56 sodium ion cells and are arranged in parallel with a capacitor C2 connected between V bat+ and V bat-A feature of using the second battery chemistry cells 56 with the first battery chemistry cells 54 in the first cell set 50 is an improved ability to estimate the state of charge / state of health (SOC / SOH) across the first cell set 50. In particular, the first battery chemistry cells 54 derive voltage in a non-linear manner, while the second chemistry cells 56 dissipate energy in a more linear manner with a more linear relationship curve between SOC / SOH and voltage. Therefore, a voltage across the at least one second battery chemistry cell 56 in the first cell set 50 can be measured to determine an estimated SOC / SOH of the first cell set 50. In the illustrated example, the first cell set 50 has an ampere-hour (Ah) rating that is greater than twice the Ah rating of the second cell set 52.For example, the first cell set 50 could have a storage capacity of 150 Ah and the second cell set 52 could have a storage capacity of 50 Ah.

[0033] The second cell set 52 is configured in series with a DC-DC converter 58. The DC-DC converter 58 includes semiconductor switches S1 and S2 in series with resistor R Land inductor L. The DC-DC converter 58 is used when a switch K2 is open, and the DC-DC converter 58 is bypassed when the switch K2 is closed. One feature of the DC-DC converter 58 is changing an output voltage of the second cell set 52 to match a voltage of the first cell set 50. Alternatively, the DC-DC converter 58 can increase the voltage of the second cell set 52 so that it is greater than the voltage of the first cell set 50, as will be explained in more detail below. A capacitor C3 is connected in parallel with the second cell set 52, and the DC-DC converter 58 is connected between the voltages V dc+ and V dc- .

[0034] Fig. 3 shows an example of a method 100 for operating the battery pack assembly 13. The method 100 begins by determining an operating strategy for the battery pack assembly 13 (block 102). In the illustrated example, the operating strategies include a fast charge mode (block 104), a normal temp operating mode (block 106), and a low temp operating mode (block 108). The first and second cell sets 50, 52 are arranged in parallel or in series with battery terminals on a load / charger 62, depending on the operating strategy of the battery pack assembly 13.

[0035] If the selected operating strategy includes the fast charge mode from block 104, the method 100 begins by charging the second cell set 52 with a power charging source, such as the load / charger 62 (block 110). To charge the second cell set 52, the method 100 bypasses the DC-DC converter 58 by closing switch K2 and disconnects the first cell set 50 by opening switch K1. A feature of charging the second cell set 52 separately from the first cell set 50 is that the second cell set 52 charges faster than the first cell set 50 due to the different battery chemistries of the two cell sets. This allows the battery pack assembly 13 to initially reach a greater charge percentage more quickly because the second cell set 52, which is sodium-ion cells, charges faster than the first cell set 50, which is primarily LFP cells.Once the second cell set 52 is charged to a desired level, the second cell set 52 is disconnected by opening switch K2 and closing switch K1. The first cell set 50 can then be charged to a desired predetermined charge level (block 112).

[0036] If the selected operating strategy includes the normal temperature operating mode from block 106, the method 100 compares the voltages of the first cell set 50 with the second cell set 52. If the voltage of the first cell set 50 is equal to the second cell set 52 (block 114), the DC-DC converter 58 is bypassed by closing switch K2, and the first cell set 50 and the second cell set 52 are operated together in parallel (block 116) to supply power to the load 62.

[0037] If the voltages of the first cell set 50 and the second cell set 52 are not equal, the method 100 proceeds to block 118. In block 118, the method 100 will determine if the voltage of the second cell set 52 is greater than the voltage of the first cell set 50. If the voltage of the second cell set 52 is greater than the voltage of the first cell set 50, the method 100 will proceed to block 120. In block 120, the method will disconnect the first cell set 50 by opening switch K1 and closing switch K2 to use the second cell set 52 to power the load 62. The method 100 will use the second cell set 52 to power the load 62 until the voltage of the second cell set 52 equals the voltage of the first cell set 50.If the voltage of the first cell set 50 matches the voltage of the second cell set 52, both the first and second cell sets 50, 52 may be operated together in parallel to power the load 62. If the method determines that the voltage of the second cell set 52 is not greater than the voltage of the first cell set 50, the method 100 will proceed to block 122.

[0038] In block 122, the method 100 will determine whether the voltage of the first cell set 50 is greater than the voltage of the second cell set 52. If the voltage of the first cell set 50 is greater than the voltage of the second cell set 52, the method 100 will proceed to block 124. In block 124, the method 100 may instruct the DC-DC converter 58 to increase the voltage of the second cell set 52 to match the voltage of the first cell set 50 in order to power the load 62 having the first and second cell sets 50, 52 in parallel.

[0039] Alternatively, the method 100 may disconnect the second cell set 52 from the load 62 by opening switch K2 and supplying power to the load 62 with the first cell set 50 until the voltage of the first cell set 50 equals the voltage of the second cell set 52. When the voltages of the first and second cell sets 50, 52 match, both the first and second cell sets 50, 52 may be used in parallel to supply power to the load 62.

[0040] If the operating strategy includes the low-temperature operating mode (block 108), the method 100 may select one of the operations from blocks 126, 128, or 130. In one example, low temperatures are below minus 10 degrees Celsius (14 degrees Fahrenheit). In block 126, the method 100 will bypass the DC-DC converter 58 by closing switch K2 and disconnect the first cell set 50 by opening switch K1. This configuration will power the load 62 using only the second cell set 52. A feature of this configuration is that the second cell set 52 operates with improved low-temperature performance compared to the first cell set 50.

[0041] Alternatively, the method 100 may continue to block 128. In block 128, the method 100 uses the DC-DC converter 58 to increase the voltage of the second cell set 52 so that it is greater than the voltage of the first cell set 50. Increasing the voltage of the second cell set 52 relative to the first cell set 50 heats the cells in the first cell set 50 to improve the operating performance of the first cell set 50 at the lower temperature.

[0042] Additionally, the method 100 may continue to block 130. In block 130, the method 100 may use the DC-DC converter 58 to adjust the voltage of the second cell set 52 to the voltage of the first cell set 50. This configuration allows the second cell set 52, with enhanced low-temperature operation, to collectively provide power to the load 62.

[0043] Fig. Figure 4 shows another example of a battery pack assembly 113. The battery pack assembly 113 is similar to the battery pack assembly 13, except where described below or shown in the drawings. Like numbers are used between similar components between the battery pack assembly 13 and the battery pack assembly 113, with the addition of a leading "1."

[0044] In the example shown, the high-voltage battery pack assembly 113 includes a first plurality of energy storage cells, for example, a first cell set 150, and a second plurality of energy storage cells, for example, a second cell set 152. The first cell set 150 is connected to the second cell set 152 in a parallel electrical configuration. The first cell set 150 includes at least one first battery chemistry cell 54 connected in series with at least one second battery chemistry cell 56. The second cell set 52 includes a plurality of second battery chemistry cells 56 connected in series without having the first battery chemistry cells 54. In the example shown, the first cell set 50 includes an ampere-hour (Ah) rating greater than twice the Ah rating of the second cell set 52.With switches K3 and K4, the first and second cell sets 150, 152 are connected in series or parallel with the load / charger 62, depending on the selected operating strategy.

[0045] Fig. 5 shows an example of a method 200 for operating the battery pack assembly 113. The method 200 begins by determining an operating strategy for the battery pack assembly 113 (block 202). In the illustrated example, the operating strategies include a fast charge mode (block 204), a normal temperature operating mode (block 206), and a low temperature operating mode (block 208). The first and second sets of cells 150, 152 are arranged in parallel or in series with the battery terminals on the load / charger 62, depending on the selected operating strategy of the battery pack assembly 113.

[0046] If the selected operating strategy includes the fast charge mode from block 204, the method 200 begins by charging the second cell set 152. To charge the second cell set 152, the method 200 bypasses the first cell set 150 by opening switch K3 and closing switch K4 (block 210). This allows the battery pack assembly 113 to attain a higher percentage of initial charge, as described above with respect to the battery pack assembly 113. Once the second cell set 152 is charged to a desired level, the second cell set 152 is disconnected by opening switch K4 and closing switch K3. The first cell set 150 can then be charged to a desired charge level (block 212).

[0047] If the selected operating strategy includes the normal temperature operating mode from block 206, the method 200 compares the voltages of the first cell set 150 with the second cell set 152 (block 214). If the voltage of the first cell set 150 is equal to that of the second cell set 152, the first cell set 150 and the second cell set 152 are operated together in parallel (block 216) to supply power to the load 62.

[0048] If the voltages of the first cell set 150 and the second cell set 152 are not equal, the method 200 will then proceed to block 218. In block 218, the method 200 will determine if the voltage of the second cell set 152 is greater than the voltage of the first cell set 150. If the voltage of the second cell set 152 is greater than the voltage of the first cell set 150, the method 200 will proceed to block 220. In block 220, the method 200 will disconnect the first cell set 150 by opening switch K3 and closing switch K4 to use the second cell set 152 to power the load 62. The method 200 will use the second cell set 152 to power the load 62 until the voltage of the second cell set 152 equals the voltage of the first cell set 150.If the voltage of the first cell set 150 matches the voltage of the second cell set 152, both the first and second cell sets 150, 152 may be operated together in parallel to power the load 62. If the method 200 determines that the voltage of the second cell set 152 is not greater than the voltage of the first cell set 150, the method 200 will proceed to block 222.

[0049] In block 222, the method 200 will determine whether the voltage of the first cell set 150 is greater than the voltage of the second cell set 152. If the voltage of the first cell set 150 is greater than the voltage of the second cell set 152, the method 200 will proceed to block 224. In block 224, the method 200 may disconnect the second cell set 152 from the load 62 by opening switch K4 and closing switch K3 to power the load 62 with the first cell set 150 until the voltage of the first cell set 150 equals the voltage of the second cell set 152. If the voltages of the first and second cell sets 150, 152 match, both the first and second cell sets 150, 152 may be used in parallel to power the load 62.

[0050] If the operating strategy includes the low-temperature operating mode (block 208), the method 200 proceeds to block 226. In block 226, the method 200 opens switch K3 to disconnect the first cell set 150 from the load 62 and closes switch K4 to connect the second cell set 152 to the load 62. A feature of this configuration is that the second cell set 152 operates with improved performance at low temperatures compared to the first cell set 150 due to differences in battery chemistry.

[0051] Fig. Figure 6 shows another example of a battery pack assembly 213. The battery pack assembly 213 is similar to the battery pack assembly 13, except where described above or shown in the drawings. Like numbers are used between similar components between the battery pack assembly 13 and the battery pack assembly 213, with the addition of a leading "2."

[0052] In the example shown, the high-voltage battery pack assembly 213 includes a first plurality of energy storage cells, such as a first cell set 251, and a second plurality of energy storage cells, such as the second cell set 252. The first cell set 251 is connected in parallel to a charger 262C and a DC-DC converter 258, such as a bidirectional buck / boost DC-DC converter. The first cell set 251 includes at least one additional battery chemistry cell 253, such as silicon anode cells, connected in series.

[0053] The second cell set 252 is connected in parallel to a load 262L and the DC-DC converter 258. The second cell set 252 includes a plurality of second battery chemistry cells 56 connected in series without any other chemistry cells in the second cell set 252.

[0054] When charging the first and second cell sets 251, 252, the first cell set 251 is connected directly to the charger 262C so that the cells 253 are not limited by an output of the DC-DC converter 258. The second cell set 252 charges at a rate limited by an output of the DC-DC converter 258. The DC-DC converter 258 can be sized based on continuous discharge and direct current fast charge (DCFC) requirements. In particular, the DC-DC converter 258 is sized such that its output is greater than a maximum DCFC current rate of the cells 56 in the second cell set 252. Furthermore, the DC-DC converter 258 can be sized such that its maximum power is greater than a maximum continuous discharge fraction of the motor vehicle 40.A feature of the battery pack assembly 213 is the long cycle life of the cells 252 with Si anode cells and the cost reduction by using the sodium ion cells 56 compared to using only Si anode cells.

[0055] The detailed description and the drawings or figures are supportive and descriptive of the present teachings, but the scope of the present teachings is defined solely by the claims. While some of the best modes and other embodiments for carrying out the present teachings have been described in detail, various alternative designs and embodiments exist for carrying out the present teachings, which are defined in the appended claims.

Claims

[1] An electrical system comprising: a high-voltage battery pack assembly comprising: a first cell set having a first plurality of energy storage cells; and a second cell set having a second plurality of energy storage cells connectable to the first cell set, the first cell set including at least one first battery chemistry cell and the second cell set including at least one second battery chemistry cell; at least one switch in electrical connection with the first set of cells or the second set of cells; Battery terminals in electrical communication with at least one of the first cell set or the second cell set; and a controller configured to: determine an operating strategy of the high-voltage battery pack assembly; and in response to the operating strategy of the high-voltage battery pack, place at least one of the first cell set or the second cell set into electrical communication with the battery terminals. [2] The electrical system of claim 1, wherein the controller is configured to isolate the first set of cells from the battery terminals when the operating strategy includes operating the electrical system at a temperature below a predetermined threshold. [3] The electrical system of claim 1, wherein the controller is configured to increase an output voltage of the second cell set with a DC-DC converter when the operating strategy includes operating the electrical system at a temperature below a predetermined threshold to heat the first cell set. [4] The electrical system of claim 1, wherein the controller is configured to adapt an output voltage of the second cell set to the first cell set with a DC-DC converter when the operating strategy includes operating the electrical system at a temperature below a predetermined threshold and the at least one switch connects the first cell set in parallel with the second cell set. [5] The electrical system of claim 1, wherein the operating strategy includes operating the electrical system above a predetermined threshold temperature. [6] The electrical system of claim 5, wherein the controller is configured to position the at least one switch to connect the first set of cells in parallel with the second set of cells. [7] The electrical system of claim 5, wherein the controller is configured to position the at least one switch to isolate the first set of cells from the battery terminals until a second voltage across the second set of cells is reduced to equal a first voltage across the first set of cells. [8] The electrical system of claim 5, wherein the controller is configured to use a DC-DC converter to increase an output voltage of the second cell set when the first cell set has an output voltage greater than an output voltage of the second cell set. [9] The electrical system of claim 5, wherein the controller is configured to disconnect the second set of cells from the battery terminals when an output voltage of the first set of cells is greater than an output voltage of the second set of cells. [10] The electrical system of claim 1, wherein the controller is configured to disconnect the first set of cells from the battery terminals to charge the second set of cells when the battery terminals are in electrical communication with a power charging source.

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