System and method for operating hybrid chemical power source

Abstract

An electrical system includes a high voltage battery pack assembly having a first battery pack having a first set of energy storage cells and a second battery pack having a second set of energy storage cells connectable to the first battery pack. The first battery pack comprises at least one first battery chemical unit, and the second battery pack comprises at least one second battery chemical unit. At least one switch is in electrical communication with the first or second battery pack. The battery connection terminal is in electrical communication with at least one of the first or second battery packs. The controller is configured to determine an operating strategy of the high voltage battery pack assembly and place at least one of the first battery pack or the second battery pack in electrical communication with the battery connection terminals in response to the operating strategy of the high voltage battery pack.

Description

[0001] introduce

[0002] The electrified powertrain of a motor vehicle and other automotive electrical systems include an electrical system configured to energize one or more motors to produce drive torque. For example, a traction motor may be connected to the wheels of an electric vehicle, and the output torque generated is directed to the wheels to propel the electric vehicle on a road surface. To this end, the high voltage bus of the electric vehicle is connected to a rechargeable energy storage system ("RESS"), the main component of which is a propulsion battery pack having a number and configuration of electrochemical cells suitable for the application. When the traction motor is configured as a multi-phase / alternating current ("AC") machine, the connection of the battery pack to the motor can be achieved through an intermediate power inverter module. Summary of the invention

[0003] An electrical system is disclosed herein. The electrical system includes a high-voltage battery pack assembly having a first battery pack and a second battery pack, the first battery pack having a first group of energy storage cells, the second battery pack having a second group of energy storage cells connectable to the first battery pack. The first battery pack includes at least one first battery chemistry cell, and the second battery pack includes at least one second battery chemistry cell. At least one switch is electrically connected to the first battery pack or the second battery pack. A battery connection terminal is electrically connected to at least one of the first battery pack or the second battery pack. 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, at least one of the first battery pack or the second battery pack is placed in electrical communication with the battery connection terminal.

[0004] Another aspect of the present disclosure may be where the controller is configured to isolate the first battery pack from the battery connection terminals when the operating strategy includes operating the electrical system at a temperature below a predetermined threshold.

[0005] Another aspect of the disclosure may be where the controller is configured to boost the output voltage of the second battery pack using the DC-DC converter when the operating strategy includes operating the electrical system at a temperature below a predetermined threshold to heat the first battery pack.

[0006] Another aspect of the present disclosure may be wherein the controller is configured to match the output voltage of the second battery pack to the first battery pack using a DC-DC converter when the operating strategy includes operating the electrical system at a temperature below a predetermined threshold and at least one switch connects the first battery pack in parallel with the second battery pack.

[0007] Another aspect of the present disclosure may be where the operating strategy includes operating the electrical system above a predetermined threshold temperature.

[0008] Another aspect of the present disclosure may be where the controller is configured to position the at least one switch to place the first battery pack in parallel with the second battery pack.

[0009] Another aspect of the invention may be where the controller is configured to position at least one switch to isolate the first battery pack from the battery connection terminals until a second voltage across the second battery pack is reduced to match the first voltage across the first battery pack.

[0010] Another aspect of the present disclosure may be where the controller is configured to boost an output voltage of the second battery pack using a DC-DC converter when the first battery pack comprises an output voltage greater than that of the second battery pack.

[0011] Another aspect of the present disclosure may be wherein the controller is configured to disconnect the second battery pack from the battery connection terminal when an output voltage of the first battery pack is greater than an output voltage of the second battery pack.

[0012] Another aspect of the present disclosure may be where the controller is configured to disconnect the first battery pack from the battery connection terminal to charge the second battery pack when the battery connection terminal is in electrical communication with a power charging source.

[0013] Another aspect of the present disclosure may be wherein the controller is configured to bypass the DC-DC converter when charging the second battery pack.

[0014] Another aspect of the present invention may be wherein the controller is configured to isolate the second battery pack when the output voltage of the second battery pack reaches a predetermined charging threshold, and the controller is configured to position at least one switch to isolate the second battery pack and charge the first battery pack using a charging source electrically connected to the battery connection terminals.

[0015] Another aspect of the present disclosure may be wherein the first battery pack includes a group of lithium iron phosphate cells and at least one sodium ion cell, and the second battery pack includes a group of sodium ion cells.

[0016] Another aspect of the present disclosure may be wherein the controller is configured to measure the state of charge of the first battery pack by measuring a voltage across at least one sodium ion cell.

[0017] Another aspect of the present disclosure may be where the controller is configured to position the at least one switch to place the second battery pack in series with the DC-DC converter.

[0018] Another aspect of the present disclosure may be where the first battery pack includes a set of silicone anode cells and the second battery pack includes sodium ion cells, wherein the first battery pack and the second battery pack are connected to a DC-DC converter.

[0019] A method of operating an electrical system is disclosed herein. The method includes determining an operating strategy for a high-voltage battery pack assembly. The high-voltage battery pack assembly includes a first battery pack and a second battery pack connected to the first battery pack. The first battery pack includes at least one first battery chemistry cell, and the second battery pack includes at least one second battery chemistry cell. The method also includes placing the first battery pack and the second battery pack in electrical communication with a battery connection terminal in response to the operating strategy for the high-voltage battery pack.

[0020] A vehicle system is disclosed herein. The vehicle system includes a traction battery that forms a high-voltage battery assembly having a first battery pack and a second battery pack connected to the first battery pack. The first battery pack includes at least one first battery chemistry cell and the second battery pack 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 assembly. The controller is also configured to place at least one of the first battery pack or the second battery pack in electrical communication with a battery connection terminal in response to the operating strategy of the high-voltage battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 An exemplary electrical system configured to charge a high voltage battery pack with a high voltage battery pack configured to provide power to a low voltage bus is shown.

[0022] Figure 2 is a schematic diagram of an exemplary battery pack assembly.

[0023] Figure 3 Show operation Figure 2 An exemplary method of battery assembly.

[0024] Figure 4 Another exemplary battery pack assembly is shown.

[0025] Figure 5 Shows an operation Figure 4 A method for assembling a battery pack.

[0026] Figure 6 Yet another exemplary battery pack assembly is shown.

[0027] The drawings are not necessarily drawn to scale and may present somewhat simplified representations of various preferred features of the present disclosure as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes. Details related to these features will be determined in part by the specific intended application and use environment. DETAILED DESCRIPTION

[0028] Referring to the drawings, like reference numerals correspond to the same or similar components throughout the several views. Figure 1An electrical system 12 is shown, such as an electrified powertrain of a motor vehicle 40 having a vehicle body 41 defining a vehicle interior 42 . Figure 1 The motor vehicle 40 may also include a front trunk ("Frunk") 46 or another compartment that provides a user with access to a charging socket REC. The motor vehicle 40 also includes running wheels 43 for traveling along a road. The wheels 43 may be driven / powered or undriven / idling by the electrical system 12 as described in more detail below.

[0029] The electrical system 12 includes separate high voltage and low voltage buses. The high voltage bus 20-H is in electrical communication with a high voltage battery pack assembly 13 such as a traction battery, while the low voltage bus 20-L is in electrical communication with an auxiliary battery (“B AUX ”) 30 is electrically connected. At least an on-board charging module (“OBCM”) 22 (including an input connected to the charging receptacle REC) acts as a power converter to convert AC power from the charging station 48 into DC power at the outlet 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, wherein the input is connected to the high voltage bus 20-H and the output is connected to the low voltage bus 20-L to charge the auxiliary battery 30 and powered vehicle accessories such as heated seats, power windows, or a navigation system. Both the OBCM 22 and the APM 21 communicate with the electronic controller 28 in the electrical system 12.

[0030] The electronic controller 28 may include a computer and / or processor and include software, hardware, memory, algorithms, connections, etc. for managing and controlling the operation of the motor vehicle 40. Figure 5 The method generally shown in the drawings may be implemented as a program or algorithm that may be operated in part on the controller 28. It should be understood that the controller 28 may include devices capable of analyzing data from sensors, comparing data, making decisions necessary to control the operation of the motor vehicle 40, and performing tasks necessary to control the operation of the motor vehicle 40.

[0031] The controller 28 can be implemented as one or more digital computers or mainframes, each having one or more processors, read-only memory (ROM), random access memory (RAM), electrically programmable read-only memory (EPROM), optical drives, magnetic drives, etc., high-speed clocks, analog-to-digital (A / D) circuits, digital-to-analog (D / A) circuits and input / output (I / O) circuits, I / O devices and communication interfaces, and signal conditioning and buffering electronics. Computer-readable memory can include non-temporary / tangible media that participate in providing data or computer-readable instructions. The memory can be non-volatile or volatile. Non-volatile media can include, for example, optical or magnetic disks and other permanent memories. Exemplary volatile media can include dynamic random access memory (DRAM), which can constitute main memory. Other examples of memory embodiments include floppy disks, hard disks, tapes or other magnetic media, CD-ROMs, DVDs and / or other optical media, and other possible memory devices such as flash memory.

[0032] Controller 28 includes tangible, non-transitory memory having recorded thereon computer executable instructions including one or more algorithms for regulating operation of motor vehicle 40. The subject algorithm(s) may specifically include an algorithm configured to optimize motor vehicle 40 energy usage.

[0033] In the example shown, for example Figure 1 The features and functions of the power converter of the auxiliary power module 21 or the onboard charging module 22 can be partially or fully integrated into the structure of the electrical system 12. In addition, the present teachings are applicable to various mobile and fixed variations of the electrical system 12, including but not limited to electrified power systems of aircraft, ships, rail vehicles, farm equipment, transportation equipment and other land, sea or air mobile platforms, as well as power plants, cranes, conveyor systems, etc. Therefore, the present teachings are applicable to various mobile and fixed variations of the electrical system 12, including but not limited to aircraft, ships, rail vehicles, farm equipment, transportation equipment and other land, sea or air mobile platforms, as well as power plants, cranes, conveyor systems, etc. Figure 1 The depiction of the specific vehicle usage scenario shown is non-limiting and illustrates merely one possible implementation.

[0034] In addition, regarding Figure 1A representative electrical system 12 is shown, the electrical system 12 being characterized by separate high voltage and low voltage buses labeled “20-H” and “20-L,” respectively. For embodiments in which the electrical system 12 is part of a motor vehicle 40, such as, for example, an electric vehicle configured as a battery electric vehicle, a hybrid electric vehicle, or an extended-range electric vehicle, the term “high voltage” may include a battery voltage capacity of approximately 300 volts (V) or greater. This voltage level is suitable for generating drive torque for vehicle propulsion functions and for providing power to various high voltage accessories on the motor vehicle 40. The term “low voltage” itself refers to an auxiliary voltage level, typically 12-50V. Low voltage conductors (not shown) therefore connect the low voltage bus 20-L to one or more low voltage accessories located on the motor vehicle 40, including, but not limited to, lights, radios, infotainment screens, sensors, etc.

[0035] exist Figure 1 In the exemplary embodiment of the present invention, the battery pack assembly 13 is selectively connected to and disconnected from the load by a set of high voltage contactors 15. The loads applied in the illustrated configuration include a DC link capacitor (C1), a power inverter module ("inverter") 16 having a plurality of semiconductor switches 17 connected to a traction motor ("M") 18. As will be understood in the art, such as Figure 1 The inverter 16 of the illustrated inverter utilizes multiple dies of semiconductor switches 17 as fast-response on / off switching devices, such as insulated gate bipolar transistors (“IGBTs”), metal oxide semiconductor field effect transistors (“MOSFETs”), thyristors, etc. In a typical three-phase configuration of the traction motor 18, the semiconductor switches 17 are turned on or off at predetermined switching intervals to output an AC waveform to the traction motor 18.

[0036] Figure 1The traction motor 18 shown in FIG. 1 is connected to a rotatable output member 19, such as a motor shaft and connected gears (not shown). During the driving mode, the inverter 16 is controlled using pulse width modulation ("PWM") or other switching control techniques suitable for the application to energize the phase windings of the traction motor 18. As depicted, the traction motor 18 is a multi-phase AC motor, shown as a three-phase machine in this example. The rotation of the output member 19 ultimately transfers torque (To) to the connected load, including one or more wheels 43 of the motor vehicle 40. During the discharge / propulsion mode, the electrical energy stored in the constituent electrochemical cells (not shown) of the high voltage battery pack assembly 13 is used to power the rotation of one or more wheels 43. Other embodiments of the motor vehicle 40 may use more or fewer wheels 43. In addition, some wheels 43 may be undriven / idling (e.g., in a rear-wheel drive or front-wheel drive configuration), or the wheels 43 may be driven (e.g., in an all-wheel drive or four-wheel drive configuration), without limitation.

[0037] Figure 1 The electrical system 12 of the motor vehicle 40 may also include additional components for providing power to various systems or functions on the motor vehicle 40, for example, the high voltage battery pack assembly 13 is depicted as being connected to the APM 21. Thus, the APM 21 is operable to reduce the level of the DC voltage of the high voltage bus 20-H (e.g., 300V or greater as described above) to a typical 12-50V auxiliary voltage level on the low voltage bus 20-L. An auxiliary battery 30, such as a 12V / 48V lead acid or lithium auxiliary battery, may be electrically connected to the APM 21, wherein the internal switching operation of the APM ensures that the auxiliary battery 30 remains charged, i.e., the auxiliary battery voltage (V AUX ) is equal to approximately 12-50V.

[0038] Figure 2 An exemplary high voltage battery pack assembly 13 is shown. In the example shown, the high voltage battery pack assembly 13 includes a first plurality of energy storage cells, such as a first battery pack 50, and a second plurality of energy storage cells, such as a second battery pack 52. The first battery pack 50 is connected to the second battery pack 52 in a parallel electrical configuration. The first battery pack 50 includes at least one first battery chemistry cell 54 connected in series with at least one second battery chemistry cell 56. The second battery pack 52 includes a plurality of second battery chemistry cells 56 connected in series without the first battery chemistry cell 54.

[0039] In the example shown, the first battery chemistry 54 comprises a lithium iron phosphate (LFP) cell and the second battery chemistry 56 comprises a sodium ion cell and is coupled to a first battery chemistry 54 and a second battery chemistry 56. bat+ and V bat-A capacitor C2 is arranged in parallel between the first battery pack 50 and the second battery chemistry unit 56. One feature of using the second battery chemistry unit 56 with the first battery chemistry unit 54 in the first battery pack 50 is an improved ability to estimate the state of charge / state of health (SOC / SOH) on the first battery pack 50. In particular, the first battery chemistry unit 54 consumes voltage in a non-linear manner, while the second battery chemistry unit 56 consumes energy in a more linear manner, and therefore, has a more linear relationship curve between SOC / SOH and voltage. In this way, the voltage across at least one second battery chemistry unit 56 in the first battery pack 50 can be measured to provide an estimated SOC / SOH of the first battery pack 50. In the example shown, the first battery pack 50 includes an ampere-hour (Ah) rating that is greater than twice the Ah rating of the second battery pack 52. For example, the first battery pack 50 may include a storage capacity of 150Ah, and the second battery pack 52 includes a storage capacity of 50Ah.

[0040] The second battery pack 52 is configured to be connected in series with a DC-DC converter 58. The DC-DC converter 58 includes a resistor R L Semiconductor switches S1 and S2 are connected in series with the inductor L. The DC-DC converter 58 is used when the 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 to change the output voltage of the second battery pack 52 to match the voltage of the first battery pack 50. Alternatively, the DC-DC converter 58 can increase the voltage of the second battery pack 52 to be greater than the voltage of the first battery pack 50, which will be discussed in more detail below. The capacitor C3 is connected in parallel with the second battery pack 52, and the DC-DC converter 58 is connected across the voltage V dc+ and V dc- between.

[0041] Figure 3 An exemplary method 100 of operating a battery pack assembly 13 is shown. The method 100 begins by determining an operating strategy for the battery pack assembly 13 (block 102). In the example shown, the operating strategy includes a fast charge mode (block 104), a normal temperature operating mode (block 106), and a low temperature operating mode (block 108). The first and second battery packs 50, 52 are positioned in parallel or in series with the battery connection terminals at the load / charger 62 according to the operating strategy of the battery pack assembly 13.

[0042] When the selected operating strategy includes a fast charge mode from box 104, the method 100 begins by charging the second battery pack 52 with a power charging source such as the load / charger 62 (box 110). To charge the second battery pack 52, the method 100 bypasses the DC-DC converter 58 by closing switch K2 and disconnects the first battery pack 50 by opening switch K1. One feature of charging the second battery pack 52 separately from the first battery pack 50 is that the second battery pack 52 charges faster than the first battery pack 50 due to the difference in battery chemistry cells between the two battery packs. This allows the battery pack assembly 13 to initially obtain a greater percentage of charge faster because the second battery pack 52 of sodium ion cells will charge at a faster rate than the first battery pack 50 of primarily LFP cells. Once the second battery pack 52 has been charged to the desired level, the second battery pack 52 is disconnected by opening switch K2 and closing switch K1. The first battery pack 50 can then be charged to the desired predetermined charge level (box 112).

[0043] When the selected operating strategy includes the normal temperature operating mode from box 106, the method 100 compares the voltage of the first battery pack 50 and the second battery pack 52. If the voltage of the first battery pack 50 is equal to the voltage of the second battery pack 52 (box 114), the DC-DC converter 58 is bypassed by closing the switch K2, and the first battery pack 50 and the second battery pack 52 are operated in parallel together (box 116) to provide power to the load 62.

[0044] If the voltages of the first battery pack 50 and the second battery pack 52 are not equal, the method 100 will proceed to box 118. At box 118, the method 100 will determine whether the voltage of the second battery pack 52 is greater than the voltage of the first battery pack 50. If the voltage of the second battery pack 52 is greater than the voltage of the first battery pack 50, the method 100 will proceed to box 120. At box 120, the method will disconnect the first battery pack 50 by opening switch K1 and closing switch K2 to use the second battery pack 52 to provide power to the load 62. The method 100 will use the second battery pack 52 to provide power to the load 62 until the voltage of the second battery pack 52 matches the voltage of the first battery pack 50. When the voltage of the first battery pack 50 matches the voltage of the second battery pack 52, the first and second battery packs 50, 52 can be operated together in parallel to provide power to the load 62. If the method determines that the voltage of the second battery pack 52 is not greater than the voltage of the first battery pack 50, the method 100 will proceed to box 122.

[0045] At block 122, the method 100 will determine whether the voltage of the first battery pack 50 is greater than the voltage of the second battery pack 52. If the voltage of the first battery pack 50 is greater than the voltage of the second battery pack 52, the method 100 will proceed to block 124. At block 124, the method 100 may instruct the DC-DC converter 58 to increase the voltage of the second battery pack 52 to match the voltage of the first battery pack 50, thereby providing power to the load 62 in a manner that the first and second battery packs 50, 52 are connected in parallel.

[0046] As an alternative, the method 100 may also disconnect the second battery pack 52 from the load 62 by opening the switch K2 and provide power to the load 62 with the first battery pack 50 until the voltage of the first battery pack 50 matches the voltage of the second battery pack 52. When the voltages of the first and second battery packs 50, 52 match, the first and second battery packs 50, 52 may be used in parallel to provide power to the load 62.

[0047] When the operating strategy includes a 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 temperature is a temperature below minus 10 degrees Celsius (14 degrees Fahrenheit). At block 126, the method 100 will bypass the DC-DC converter 58 by closing switch K2 and disconnecting the first battery pack 50 by opening switch K1. This configuration will provide power to the load 62 using only the second battery pack 52. One feature of this configuration is that the second battery pack 52 can operate with improved performance at low temperatures compared to the first battery pack 50.

[0048] Alternatively, the method 100 may proceed to block 128. At block 128, the method 100 utilizes the DC-DC converter 58 to increase the voltage of the second battery pack 52 to be greater than the voltage of the first battery pack 50. The increase in voltage of the second battery pack 52 relative to the first battery pack 50 heats the cells in the first battery pack 50, thereby improving the operating performance of the first battery pack 50 at a lower temperature.

[0049] Additionally, the method 100 may proceed to block 130. At block 130, the method 100 may utilize the DC-DC converter 58 to match the voltage of the second battery pack 52 to the voltage of the first battery pack 50. This configuration may allow the second battery pack 52 with improved low temperature operation to share in providing power to the load 62.

[0050] Figure 4 Another exemplary battery pack assembly 113 is shown. Except where described below or shown in the figures, battery pack assembly 113 is similar to battery pack assembly 13. Similar reference numerals will be used between similar components between battery pack assembly 13 and battery pack assembly 113 with the prefix "1" added.

[0051] In the example shown, the high voltage battery pack assembly 113 includes a first plurality of energy storage cells, such as a first battery pack 150, and a second plurality of energy storage cells, such as a second battery pack 152. The first battery pack 150 is connected to the second battery pack 152 in a parallel electrical configuration. The first battery pack 150 includes at least one first battery chemistry cell 54 connected in series with at least one second battery chemistry cell 56. The second battery pack 52 includes a plurality of second battery chemistry cells 56 connected in series without the first battery chemistry cell 54. In the example shown, the first battery pack 50 includes an ampere-hour (Ah) rating greater than twice the Ah rating of the second battery pack 52. Switches K3 and K4 are used to connect the first and second battery packs 150, 152 in series or in parallel with the load / charger 62 depending on the selected operating strategy.

[0052] Figure 5 An exemplary method 200 of operating a battery pack assembly 113 is shown. The method 200 begins by determining an operating strategy for the battery pack assembly 113 (block 202). In the example shown, the operating strategy includes a fast charge mode (block 204), a normal temperature operating mode (block 206), and a low temperature operating mode (block 208). Depending on the selected operating strategy for the battery pack assembly 113, the first and second groups of battery cells 150, 152 are positioned in parallel or in series with the battery connection terminals at the load / charger 62.

[0053] When the selected operating strategy includes a fast charge mode from block 204, the method 200 begins by charging the second battery pack 152. To charge the second battery pack 152, the method 200 bypasses the first battery pack 150 by opening switch K3 and closing switch K4 (block 210). This may allow the battery pack assembly 113 to obtain a greater percentage of initial charge as discussed above with respect to the battery pack assembly 13. Once the second battery pack 152 has been charged to the desired level, the second battery pack 152 is disconnected by opening switch K4 and closing switch K3. The first battery pack 150 may then be charged to the desired charge level (block 212).

[0054] When the selected operating strategy includes the normal temperature operating mode from box 206, the method 200 compares the voltage of the first battery pack 150 with the voltage of the second battery pack 152 (box 214). If the voltage of the first battery pack 150 is equal to the voltage of the second battery pack 52, the first battery pack 150 and the second battery pack 152 are operated in parallel together (box 216) to provide power to the load 62.

[0055] If the voltages of the first battery pack 150 and the second battery pack 152 are not equal, the method 200 will proceed to box 218. At box 218, the method 200 will determine whether the voltage of the second battery pack 152 is greater than the voltage of the first battery pack 150. If the voltage of the second battery pack 152 is greater than the voltage of the first battery pack 150, the method 200 will proceed to box 220. At box 220, the method 200 will disconnect the first battery pack 150 by opening switch K3 and closing switch K4 to use the second battery pack 152 to provide power to the load 62. The method 200 will continue to use the second battery pack 152 to provide power to the load 62 until the voltage of the second battery pack 152 matches the voltage of the first battery pack 150. When the voltage of the first battery pack 150 matches the voltage of the second battery pack 152, the first and second battery packs 150, 152 can work together in parallel to provide power to the load 62. If the method 200 determines that the voltage of the second battery pack 152 is not greater than the voltage of the first battery pack 150 , the method 200 will proceed to block 222 .

[0056] At block 222, the method 200 will determine whether the voltage of the first battery pack 150 is greater than the voltage of the second battery pack 152. If the voltage of the first battery pack 150 is greater than the voltage of the second battery pack 152, the method 200 will proceed to block 224. At block 224, the method 200 may disconnect the second battery pack 152 from the load 62 by opening the switch K4 and closing the switch K3, so that the first battery pack 150 provides power to the load 62 until the voltage of the first battery pack 150 matches the voltage of the second battery pack 152. When the voltages of the first and second battery packs 150, 152 match, both the first and second battery packs 150, 152 may be used in parallel to provide power to the load 62.

[0057] When the operating strategy includes a low temperature operating mode (block 208), the method 200 proceeds to block 226. At block 226, the method 200 opens switch K3 to disconnect the first battery pack 150 from the load 62, and closes switch K4 to connect the second battery pack 152 to the load 62. One feature of this configuration is that the second battery pack 152 can operate with improved performance at low temperatures compared to the first battery pack 150 due to differences in battery chemistry.

[0058] Figure 6 Yet another exemplary battery pack assembly 213 is shown. Except as described above or shown in the figures, the battery pack assembly 213 is similar to the battery pack assembly 13. Similar reference numerals will be used between similar components between the battery pack assembly 13 and the battery pack assembly 213, with the prefix "2" added.

[0059] In the example shown, the high voltage battery pack assembly 213 includes a first plurality of energy storage cells, such as a first battery pack 251, and a second plurality of energy storage cells, such as a second battery pack 252. The first battery pack 251 is connected in parallel with a charger 262C, such as a bidirectional buck and boost DC-DC converter, and a DC-DC converter 258. The first battery pack 251 includes at least one additional battery chemistry cell 253, such as silicone anode cells, connected in series with each other.

[0060] The second battery pack 252 is connected in parallel with the load 262L and the DC-DC converter 258. The second battery pack 252 includes a plurality of second battery chemistry cells 56 connected in series, and no other chemistry cells are included in the second battery pack 252.

[0061] When charging the first and second battery packs 251, 252, the first battery pack 251 is directly connected to the charger 262C so that the battery 253 is not limited by the output of the DC-DC converter 258. The second battery pack 252 is charged at a rate limited by the output of the DC-DC converter 258. The DC-DC converter 258 can be sized based on continuous discharge requirements and DC fast charging (DCFC) requirements. In particular, the size of the DC-DC converter 258 is determined so that its output is greater than the maximum DCFC current rate of the cells 56 in the second battery pack 252. In addition, the size of the DC-DC converter 258 can be designed so that its maximum output is greater than the maximum continuous discharge portion of the motor vehicle 40. A feature of the battery pack assembly 213 is the long cycle life of the battery 252 with Si anode cells and the reduction in cost of using sodium ion cells 56 compared to using all Si anode cells.

[0062] The following summarizes some of the aspects explained above with numbered examples:

[0063] Example 1. An electrical system comprising:

[0064] High voltage battery pack assembly, comprising:

[0065] a first battery pack having a first plurality of energy storage cells; and

[0066] a second battery pack having a second plurality of energy storage cells connectable to the first battery pack, wherein the first battery pack includes at least one cell of a first battery chemistry and the second battery pack includes at least one cell of a second battery chemistry;

[0067] at least one switch in electrical communication with the first battery pack or the second battery pack;

[0068] a battery connection terminal in electrical communication with at least one of the first battery pack or the second battery pack; and

[0069] The controller is configured as:

[0070] determining an operating strategy for the high voltage battery pack assembly; and

[0071] In response to an operating strategy of the high-voltage battery pack, at least one of the first battery pack or the second battery pack is placed in electrical communication with the battery connection terminal.

[0072] Example 2. An electrical system according to Example 1, wherein the controller is configured to isolate the first battery pack from the battery connection terminals when the operating strategy includes operating the electrical system at a temperature below a predetermined threshold.

[0073] Example 3. An electrical system according to Example 1, wherein the controller is configured to utilize a DC-DC converter to increase the output voltage of the second battery pack when the operating strategy includes operating the electrical system at a temperature below a predetermined threshold to heat the first battery pack.

[0074] Example 4. An electrical system according to Example 1, wherein the controller is configured to match the output voltage of the second battery pack with the first battery pack using 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 battery pack in parallel with the second battery pack.

[0075] Example 5. The electrical system of Example 1, wherein the operating strategy includes operating the electrical system above a predetermined threshold temperature.

[0076] Example 6. An electrical system according to Example 5, wherein the controller is configured to position the at least one switch to place the first battery pack in parallel with the second battery pack.

[0077] Example 7. An electrical system according to Example 5, wherein the controller is configured to position the at least one switch to isolate the first battery pack from the battery connection terminals until a second voltage across the second battery pack is reduced to match a first voltage across the first battery pack.

[0078] Example 8. The electrical system of Example 5, wherein the controller is configured to boost the output voltage of the second battery pack using a DC-DC converter when the first battery pack comprises an output voltage greater than the output voltage of the second battery pack.

[0079] Example 9. An electrical system according to Example 5, wherein the controller is configured to disconnect the second battery pack from the battery connection terminals when the output voltage of the first battery pack is greater than the output voltage of the second battery pack.

[0080] Example 10. An electrical system according to Example 1, wherein the controller is configured to disconnect the first battery pack from the battery connection terminals to charge the second battery pack when the battery connection terminals are electrically connected to a power charging source.

[0081] Example 11. The electrical system of Example 10, wherein the controller is configured to bypass the DC-DC converter when charging the second battery pack.

[0082] Example 12. An electrical system according to Example 10, wherein the controller is configured to isolate the second battery pack when the output voltage across the second battery pack reaches a predetermined charging threshold, and the controller is configured to position the at least one switch to isolate the second battery pack and charge the first battery pack using a power charging source electrically connected to the battery connection terminals.

[0083] Example 13. The electrical system of Example 1, wherein the first battery pack includes a plurality of lithium iron phosphate cells and at least one sodium ion cell, and the second battery pack includes a plurality of sodium ion cells.

[0084] Example 14. The electrical system of Example 13, wherein the controller is configured to measure the state of charge of the first battery pack by measuring a voltage across the at least one sodium ion cell.

[0085] Example 15. The electrical system of Example 13, wherein the controller is configured to position the at least one switch to place the second battery pack in series with a DC-DC converter.

[0086] Example 16. An electrical system according to Example 1, wherein the first battery pack includes a plurality of silicone anode cells and the second battery pack includes sodium ion cells, wherein the first battery pack and the second battery pack are connected to a DC-DC converter.

[0087] Example 17. A method of operating an electrical system, the method comprising:

[0088] determining an operating strategy for a high voltage battery pack assembly, wherein the high voltage battery pack assembly includes a first battery pack and a second battery pack connected to the first battery pack, wherein the first battery pack includes at least one cell of a first battery chemistry and the second battery pack includes at least one cell of a second battery chemistry; and

[0089] The first battery pack and the second battery pack are placed in electrical communication with battery connection terminals in response to an operating strategy of the high voltage battery pack.

[0090] Example 18. The method of Example 17, comprising isolating the first battery pack from the battery connection terminals when the operating strategy includes operating the electrical system at a temperature below a predetermined threshold.

[0091] Example 19. The method of Example 17, comprising positioning at least one switch to place the first battery pack in parallel with the second battery pack when the operating strategy includes operating the electrical system above a predetermined threshold temperature.

[0092] Example 20. A vehicle system comprising:

[0093] a traction battery forming a high voltage battery pack assembly having a first battery pack and a second battery pack connected to the first battery pack, wherein the first battery pack includes at least one cell of a first battery chemistry and the second battery pack includes cells of a second battery chemistry;

[0094] a traction motor in communication with the traction battery; and

[0095] The controller is configured as:

[0096] determining an operating strategy for the high voltage battery pack assembly; and

[0097] In response to an operating strategy of the high voltage battery pack, at least one of the first battery pack or the second battery pack is placed in electrical communication with a battery connection terminal.

[0098] The detailed description and drawings support and describe the present teaching, but the scope of the present teaching is limited only by the claims. Although some best modes and other embodiments for carrying out the present teaching have been described in detail, there are various alternative designs and embodiments for practicing the present teaching defined in the appended claims.

Claims

1. An electrical system comprising: High voltage battery pack assembly, comprising: a first battery pack having a first plurality of energy storage cells; and a second battery pack having a second plurality of energy storage cells connectable to the first battery pack, wherein the first battery pack includes at least one cell of a first battery chemistry and the second battery pack includes at least one cell of a second battery chemistry; at least one switch in electrical communication with the first battery pack or the second battery pack; a battery connection terminal in electrical communication with at least one of the first battery pack or the second battery pack; and The controller is configured as: determining an operating strategy for the high voltage battery pack assembly; and In response to an operating strategy of the high-voltage battery pack, at least one of the first battery pack or the second battery pack is placed in electrical communication with the battery connection terminal.

2. The electrical system according to claim 1, wherein: The controller is configured to isolate the first battery pack from the battery connection terminals when the operating strategy includes operating the electrical system at a temperature below a predetermined threshold.

3. The electrical system according to claim 1, wherein: The controller is configured to boost an output voltage of the second battery pack using a DC-DC converter when the operating strategy includes operating the electrical system at a temperature below a predetermined threshold to heat the first battery pack.

4. The electrical system according to claim 1, wherein: The controller is configured to match the output voltage of the second battery pack to the first battery pack using 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 battery pack in parallel with the second battery pack.

5. The electrical system according to claim 1, wherein: The operating strategy includes operating the electrical system above a predetermined threshold temperature.

6. The electrical system according to claim 5, wherein: The controller is configured to position the at least one switch to place the first battery pack in parallel with the second battery pack.

7. The electrical system according to claim 5, wherein: The controller is configured to position the at least one switch to isolate the first battery pack from the battery connection terminals until a second voltage across the second battery pack is reduced to match a first voltage across the first battery pack.

8. The electrical system according to claim 5, wherein: The controller is configured to boost an output voltage of the second battery pack using a DC-DC converter when the first battery pack comprises an output voltage greater than that of the second battery pack.

9. The electrical system according to claim 5, wherein: The controller is configured to disconnect the second battery pack from the battery connection terminals when the output voltage of the first battery pack is greater than the output voltage of the second battery pack.

10. The electrical system of claim 1, wherein: The controller is configured to disconnect the first battery pack from the battery connection terminals to charge the second battery pack when the battery connection terminals are in electrical communication with a power charging source.

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