SERIAL-PARALLELED BATTERY SYSTEMS WITH MIXED CHEMICALS

Abstract

In an exemplary embodiment, a power transmission control system comprises a traction battery arrangement designed to supply power to a vehicle's electric motor, the traction battery arrangement having a first chemistry, and an auxiliary battery arrangement selectively connected to the traction battery arrangement, the auxiliary battery arrangement having a second chemistry different from the first. The system also includes a controller designed to selectively connect the auxiliary battery arrangement to perform at least one of the operations of supplying electrical charge to the traction battery arrangement and supplying electrical power to the electric motor.

Description

INTRODUCTION

[0001] The present disclosure relates to energy or power storage and transfer, and more particularly to systems having multiple battery chemistries and methods for controlling the operation of multi-chemistry energy storage systems.

[0002] Vehicles, including gasoline- and diesel-powered vehicles, as well as electric and hybrid electric vehicles, incorporate battery storage features for purposes such as powering electric motors, electronics, and other vehicle subsystems. Battery systems supply power to various loads, including electric motors for propulsion, as well as accessories and components such as power control modules, heaters, and cooling systems. It is desirable to provide systems that can enhance energy storage, for example, to increase driving range and improve vehicle performance. SUMMARY

[0003] In an exemplary embodiment, a power transfer control system includes a traction battery assembly configured to power an electric motor of a vehicle, the traction battery assembly having a first chemistry, and an auxiliary battery assembly selectively connected to the traction battery assembly, the auxiliary battery assembly having a second chemistry different from the first chemistry. The system also includes a controller configured to selectively connect the auxiliary battery assembly to perform at least one of providing electrical charge to the traction battery assembly and supplying electrical power to the electric motor.

[0004] In addition to one or more of the features described herein, the system includes a third battery assembly including a battery cell having a third chemistry different from the first and second chemistry, the battery cell being connected in series with the traction battery assembly.

[0005] In addition to one or more of the features described herein, the auxiliary battery assembly is a high energy battery assembly having an energy density greater than the energy density of the traction battery assembly.

[0006] In addition to one or more of the features described herein, the system includes a DC-DC converter connected in parallel with the traction battery assembly and the auxiliary battery assembly, the DC-DC converter configured to adjust an output voltage of the auxiliary battery assembly.

[0007] In addition to one or more of the features described herein, the controller is configured to connect the auxiliary battery assembly in series with the traction battery assembly and to supply the electrical charge to the traction battery assembly via the DC-DC converter during vehicle propulsion to increase the range of the vehicle.

[0008] In addition to one or more of the features described herein, the controller is configured to connect the auxiliary battery assembly based on a state of charge (SOC) of the traction battery assembly being below a SOC threshold and to provide the electrical charge to maintain the SOC of the traction battery assembly at or above the SOC threshold.

[0009] In addition to one or more of the features described herein, the controller is configured to connect the auxiliary battery assembly in parallel with the traction battery assembly and to supply electrical power to the electric motor via the DC-DC converter, with the electrical power bypassing the traction battery assembly.

[0010] In addition to one or more of the features described herein, the vehicle is configured to be connected to a power source for charging the traction battery assembly, and the controller is configured to control a charging process that prioritizes the provision of charging power to the traction battery assembly.

[0011] In addition to one or more of the features described herein, the charging operation includes providing an amount of power to charge the traction battery assembly to a desired SOC and providing a remaining amount of power to charge the auxiliary battery assembly.

[0012] In addition to one or more of the features described herein, the controller is configured to control the charging process based on a predictive control methodology that includes predicting a state of charge of the traction battery assembly and the auxiliary battery assembly based on a quasi-steady-state model.

[0013] In another exemplary embodiment, a method for controlling power transfer includes monitoring, by a controller, a propulsion system of a vehicle, the propulsion system coupled to a mixed chemistry battery system, the mixed chemistry battery system comprising a traction battery assembly configured to power an electric motor of the propulsion system and an auxiliary battery assembly selectively coupled to the traction battery assembly, the traction battery assembly having a first chemistry and the auxiliary battery assembly having a second chemistry different from the first chemistry.The method also includes, based on receiving a request for additional propulsion, connecting the auxiliary battery assembly and providing additional power to the electric motor, and based on a state of charge (SOC) of the propulsion battery assembly being below a SOC threshold, providing electrical charge to the propulsion battery assembly from the auxiliary battery assembly.

[0014] In addition to one or more of the features described herein, the mixed chemistry battery system includes a third battery assembly including a battery cell having a third chemistry different from the first and second chemistry, the battery cell being connected in series with the traction battery assembly.

[0015] In addition to one or more of the features described herein, the auxiliary battery assembly is a high energy battery assembly having an energy density greater than the energy density of the traction battery assembly.

[0016] In addition to one or more of the features described herein, the mixed chemistry battery system includes a DC-DC converter connected in parallel with the traction battery assembly and the auxiliary battery assembly, the DC-DC converter configured to adjust an output voltage of the auxiliary battery assembly.

[0017] In addition to one or more of the features described herein, providing the electrical charge to the traction battery assembly includes connecting the auxiliary battery assembly in series with the traction battery assembly and providing the electrical charge to the traction battery assembly through the DC-DC converter during vehicle propulsion to increase the range of the vehicle.

[0018] In addition to one or more of the features described herein, providing the additional power includes connecting the auxiliary battery assembly in parallel with the traction battery assembly and providing electrical power to the electric motor via the DC-DC converter, wherein the electrical power bypasses the traction battery assembly.

[0019] In yet another exemplary embodiment, a vehicle system includes a memory having computer-readable instructions and a processing device for executing the computer-readable instructions, the computer-readable instructions controlling the processing device to perform a method. The method includes monitoring, by a controller, a propulsion system of a vehicle, the propulsion system connected to a mixed-chemistry battery system, the mixed-chemistry battery system including a traction battery assembly configured to power an electric motor of the propulsion system and an auxiliary battery assembly selectively connected to the traction battery assembly, the traction battery assembly having a first chemistry and the auxiliary battery assembly having a second chemistry different from the first chemistry.The method also includes, based on receiving a request for additional propulsion, connecting the auxiliary battery assembly and providing additional power to the electric motor, and based on a state of charge (SOC) of the propulsion battery assembly being below a SOC threshold, providing electrical charge to the propulsion battery assembly from the auxiliary battery assembly.

[0020] In addition to one or more of the features described herein, the mixed chemistry battery system includes a third battery assembly including a battery cell having a third chemistry different from the first and second chemistry, the battery cell being connected in series with the traction battery assembly.

[0021] In addition to one or more of the features described herein, the auxiliary battery assembly is a high energy battery assembly having an energy density greater than the energy density of the traction battery assembly.

[0022] In addition to one or more of the features described herein, the mixed chemistry battery system includes a DC-DC converter connected in parallel with the traction battery assembly and the auxiliary battery assembly, the DC-DC converter configured to adjust an output voltage of the auxiliary battery assembly.

[0023] The foregoing features and advantages, as well as other features and advantages of the disclosure, will be readily apparent from the following detailed description when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Further features, advantages and details are listed only as examples in the following detailed description, which refers to the drawings in which: Fig. 1 is a plan view of a motor vehicle including a mixed chemistry battery system including battery assemblies with different chemistries, according to an exemplary embodiment; Fig. 2 shows a mixed chemistry battery system connected to a propulsion system of a vehicle according to an exemplary embodiment; Fig. 3A and Fig. 3B illustrates the operating states of a mixed chemistry battery system according to an exemplary embodiment; Fig. 4 is a flowchart illustrating aspects of a method for controlling power transfer between battery systems during vehicle operation according to an exemplary embodiment; Fig. 5 schematically illustrates components of a mixed chemistry battery system and depicts aspects of a charging method according to an exemplary embodiment; Fig. 6 is a flowchart illustrating aspects of a method for charging one or more components of a mixed chemistry battery system according to an exemplary embodiment; Fig. 7 shows an example of a battery assembly comprising battery cells with different chemistries, according to an exemplary embodiment; and Fig. 8 shows a computer system according to an exemplary embodiment. DETAILED DESCRIPTION

[0025] The following description is merely exemplary and is not intended to limit the present disclosure, its application, or uses. It should be understood that throughout the drawings, corresponding reference characters designate like or corresponding parts and features. As used herein, the term module refers to a processing circuit, which may include an application-specific integrated circuit (ASIC), an electronic circuit, a processor (common, dedicated, or group), and memory executing one or more software or firmware programs, a combinational logic circuit, and / or other suitable components that provide the described functionality.

[0026] According to exemplary embodiments, methods, apparatus, and systems for energy storage and / or energy transfer are provided that utilize battery systems with multiple chemistries. One embodiment of a mixed-chemistry battery system for a vehicle includes a traction battery system having a first chemistry (e.g., lithium iron phosphate or LFP) and an auxiliary battery system having a second chemistry. The auxiliary battery system includes, for example, a battery arrangement with high energy density (relative to the traction battery system), such as a lithium metal battery (LMB) chemistry. The auxiliary battery system is selectively connected in parallel with the traction battery system and is operable to perform functions such as providing additional power to a vehicle propulsion system and increasing vehicle range.

[0027] In one embodiment, the traction battery system (e.g., a high-voltage battery pack or packs) is connected in series with a third battery system having a different chemistry than the traction battery system. The third battery system includes, for example, one or more cells or modules with a nickel-manganese-cobalt (NCM) chemistry. The third battery system provides advantages including higher overall energy density, better low-temperature performance, and better estimation of the state of charge of the traction battery system (e.g., the LFP cells).

[0028] Embodiments also include systems and methods for controlling the charging of components of a mixed-chemistry battery system. In one embodiment, a system includes a controller configured to control a charging process. The charging process allocates charge to the battery systems based on a predictive control methodology that uses a model of the battery systems to predict the state of charge and / or other parameters, and controls a charging current to apply the charging current at an optimal level that improves or maximizes charging efficiency under selected constraints.

[0029] The embodiments described herein offer numerous advantages and technical effects. The embodiments provide effective use of advanced, high-energy-density batteries to complement existing battery storage and improve vehicle performance and range. The embodiments leverage the benefits of different chemistries to improve overall performance.

[0030] For example, lithium-based battery cells, such as LFP cells, are inexpensive and have relatively long cycle life, but have relatively low energy density and are affected by low temperatures. Lithium metal cells, such as NCM cells or other advanced battery chemistries, have relatively high energy density but typically have shorter cycle life and reduced charging performance (e.g., charging speed) compared to typical traction battery chemistries. The embodiments address these limitations by combining battery chemistries to improve overall energy density, cycle life, and charging performance.

[0031] Furthermore, estimating the state of charge (SOC) of LFP cells can be challenging. Incorporating a third battery system connected in series as described herein can significantly improve the ability to accurately estimate the SOC.

[0032] The embodiments are not limited to use with a specific vehicle and may be applicable in a variety of contexts. For example, the embodiments may be used in automobiles, trucks, aircraft, construction equipment, agricultural equipment, automated factory equipment, and / or other devices or systems for which additional thermal control is desired to enhance the existing capabilities or features of a thermal control device or system.

[0033] Fig. 1 shows an embodiment of a motor vehicle 10 including a vehicle body 12 that at least partially defines a passenger compartment 14. The vehicle body 12 also supports various vehicle subsystems, including a propulsion system 16 and other subsystems for supporting the functions of the propulsion system 16 and other vehicle components, such as a braking subsystem, a suspension system, a steering subsystem, and, if the vehicle is a hybrid electric vehicle, a fuel injection subsystem, an exhaust subsystem, and others.

[0034] The vehicle 10 may be an electric vehicle (EV), a hybrid vehicle, or other vehicle. In one embodiment, the vehicle 10 is an electric vehicle that includes one or more motors and one or more propulsion systems. The propulsion system 16 is, for example, a multi-propulsion system that includes a first propulsion unit 20 and a second propulsion unit 30. The first propulsion unit 20 includes a first electric motor 22 and a first inverter 24, as well as other components such as a cooling system 26. The second propulsion unit 30 includes a second electric motor 32 and a second inverter 34, as well as other components such as a cooling system 36. The inverters 24 and 34 (e.g., traction power converter units or TPIMs) each convert direct current (DC) from a high-voltage (HV) battery system into multi-phase (e.g., two-phase, three-phase, six-phase, etc.) power.) alternating current (AC) to drive motors 22 and 32.

[0035] In the drive system 16, the drive unit 20 and the drive unit 30 are electrically connected to the mixed-chemistry battery system 40. The battery system 40 or its components may be configured as a rechargeable energy storage system (RESS).

[0036] The mixed-chemistry battery system 40 includes one or more battery assemblies. The battery system 40 includes, for example, one or more high-voltage battery packs, such as a first battery pack 44 connected to the inverter 24 and a second battery pack 46 connected to the inverter 34. The battery packs 44 and 46 (and associated components such as the controller of a RESS or battery management system (BMS)) are a primary power source for the propulsion system 16 and are referred to as the propulsion battery system.

[0037] Battery pack 44 includes a plurality of battery modules 48, and battery pack 46 includes a plurality of battery modules 50. Each module 48, 50 includes a number of individual cells (not shown). In one embodiment, battery packs 44 and 46 can be independently charged and can be used to independently provide power for propulsion, power delivery, and / or charging.

[0038] Each battery module 48, 50 includes a plurality of cells (not shown) having a selected chemistry. In one embodiment, each cell is a lithium-ion battery, such as a lithium ferrophosphate (LFP) battery. Battery packs 44 and 46 are not so limited and may have any suitable chemistry. Other examples include nickel-metal hydride and lead-acid chemistries.

[0039] The mixed-chemistry battery system 40 can be configured to provide various output voltage levels. For example, a battery switching device 52 is included for selectively connecting the battery pack 44 in series with the battery pack 46 to provide a relatively high voltage. The battery switching device 52 can also be operated to connect the battery packs in parallel to provide a relatively low voltage.

[0040] The vehicle 10 includes a number of additional battery assemblies (e.g., one or more additional cells, modules, packs, etc.). In one embodiment, the mixed-chemistry battery system 40 includes an auxiliary battery system 60 that is connected to the battery packs 44 and 46 or that can be selectively connected in parallel. The auxiliary battery system 60 is provided to supplement the battery packs 44 and 46, for example, by providing additional power to the propulsion system 16 and / or providing energy to the battery pack 44 and / or 46 to increase the range of the vehicle 10. The auxiliary battery system 60 includes at least one auxiliary battery pack 62, which may have the same nominal voltage as the battery packs 44 and 46 (e.g., 400 V), but is not limited to this.

[0041] The auxiliary battery pack 62 is connected to the battery system 40 via a conversion device, such as a DC-DC converter 64. Control of the DC-DC converter 64 and / or the auxiliary battery system 60 may be performed using any suitable processing device or processor, such as a battery management system (BMS) controller or other controller associated with the battery packs 44 and 46, a charging controller, a motor controller, or others.

[0042] The auxiliary battery system 60, in one embodiment, is a high-energy-density system (i.e., it has a higher energy density than the battery packs 44 and 46). For example, the battery pack 62 includes a plurality of high-energy-density cells. Such cells have high-energy-density chemistries such as lithium metal cells (e.g., LMB cells), Si-anode cells (lithium-ion cells with silicon-based anodes), and others.

[0043] In one embodiment, the vehicle 10 includes one or more additional cells 54 that are connected in series with the cells of the battery pack 46 (and may also be connected in series with the battery pack 44 when the battery switching device 52 is closed). Although the cells 54 are shown as being connected to the battery pack 46, one or more cells 54 may also be connected in series with the battery pack 44. It should be noted that the embodiments are not limited to the number or configuration of the cells 54 shown in Fig. 1 are shown.

[0044] In one embodiment, cells 54 have a battery chemistry that differs from the chemistry of battery pack 44 and / or 46. For example, cells 54 are NCM cells, and battery packs 44 and 46 have a lithium-ion chemistry, such as LFP.

[0045] Cells 54 may have various uses and functions. Cells 54 provide low-temperature performance improvements and may be used as "virtual sensors" to facilitate estimation of the SOC of battery pack 46. SOC estimation may be performed by estimating the SOC of cells 54 and the SOC of battery pack 46 using known techniques such as coulomb counting. The estimates are combined to reduce the error of an estimate of the SOC of battery pack 46 (e.g., to 3% or less).

[0046] The vehicle 10 also includes a charging system that can be used to charge the battery packs 44 and 46 (and the cells 54), to charge the auxiliary battery system 60, and / or to provide power to charge another energy storage system (e.g., vehicle-to-vehicle (V2V) and / or vehicle-to-everything (V2X) charging). The charging system includes one or more conversion devices for controlling aspects of charging and / or discharging. For example, at least one conversion device provides conversion between AC and DC power and / or voltage regulation. The conversion device can be a bidirectional conversion device, allowing a charging port to be used for either charging or discharging.

[0047] In one embodiment, the charging system includes a charging control device 66, such as an on-board charging module (OBCM). The charging control device 66 includes a conversion device in the form of a charger (charging circuit) that includes AC-to-DC conversion and DC-to-DC conversion devices. For example, the charging control device 66 enables both charging and discharging to and from an external power storage device, such as the battery system of another vehicle (V2V charging). The charging control device 66 connects the battery system 40 to a charging port 68 for charging vehicle battery systems and / or for charging external storage systems.

[0048] The vehicle 10 also includes a computer system 70 that includes one or more processing devices 72 and a user interface 74. The various processing devices and units may communicate with each other via a communication device or system, such as a Controller Area Network (CAN) or a Transmission Control Protocol (TCP) bus.

[0049] Fig. Figure 2 shows an embodiment of the mixed-chemistry battery system 40. The battery pack 62 of the auxiliary battery system 60 is connected in parallel with the DC-DC converter 64 and the battery pack 44. The system 40 has a topology that enables various operating modes.

[0050] The battery pack 62 and the traction battery system (including, for example, the battery pack 44 and / or the battery pack 46) are connected in parallel via an auxiliary power bus 80. Although in Fig. 2 only the battery pack 44 is shown, it is understood that the battery pack 46 can be connected in a similar manner.

[0051] The auxiliary battery pack 62 is selectively connected to the DC-DC converter 64 and the bus 80 via a circuit including a resistor 82 and a precharge switch 84 (K1), an inductor Linput, and a capacitor Cin. The auxiliary battery pack 62 and the circuit can be connected and disconnected via a negative-side switch 86 and a positive-side switch 88 (switch K2).

[0052] Battery pack 44 is selectively connected to DC-DC converter 64 and bus 80 via an inductor Lout and a precharge circuit including a switch 90 (K3) and a resistor 92. Battery pack 44 can be connected to and disconnected from bus 80 via a negative-side switch 94 and a positive-side switch 96 (switch K4).

[0053] The DC-DC converter 64 is configured to step up or step down the voltage, for example, when the auxiliary battery pack 62 is charging or when the auxiliary battery pack 62 is providing power for propulsion. The DC-DC converter 64 can transfer power in either direction. In one embodiment, the DC-DC converter includes a half-bridge circuit with switches dp1, d1, dp2, d2, dp3, and d3.

[0054] Each of the described switches may be any suitable type of switch, such as a mechanical contactor, an electronic switch, or a solid-state switching device. Any suitable solid-state or electronic device may be used as a switch. The switch may include, for example, solid-state relays or transistors such as silicon (Si) insulated gate bipolar transistors (IGBTs) and field-effect transistors (FETs). Examples of FETs include metal-oxide-semiconductor FETs (MOSFETs), Si MOSFETs, silicon carbide (SiC) MOSFETs, gallium nitride (GaN) high electron mobility transistors (HEMTs), and SiC junction-gate FETs (JFETs). Other examples of switches that may be used include diamond, gallium oxide, and other wide bandgap (WBG) semiconductor-based switching devices.

[0055] As mentioned above, the mixed-chemistry battery system 40 is designed to operate according to various operating modes. The operating modes include, for example, a normal propulsion mode, a range-assist mode, and a power-assist mode.

[0056] In the normal operating mode, switches 86 and 88 are open, and the battery pack 44 (and / or the battery pack 46) operates normally to provide power for the propulsion and / or to power vehicle components (loads). In the normal propulsion mode, for example, the battery system 40 provides three-phase alternating current to a vehicle propulsion system via a propulsion bus 98 (and conversion devices such as a DC-DC converter and an inverter (not shown)). Various motors, components, the propulsion bus, and the charger are in Fig. 3A and Fig. 3B together represented by element 99.

[0057] In power assist mode, both battery pack 44 and auxiliary battery pack 62 are connected to bus 80 (switches K2 and K4 are closed). Battery pack 62 provides additional energy for the drive, for example, when a driver requests additional power.

[0058] As in Fig. 3A, for example, in the power assist mode, the traction battery pack 44 provides power to the motor 22 and / or 32 via the inverter 24 and / or the inverter 34 (represented by element 99). The power from the auxiliary battery pack 62 flows through the DC-DC converter 64, which can be controlled in this mode to adjust a desired output voltage, for example, to equalize the voltages of the battery pack 44 and the battery 62. The power flowing from the DC-DC converter 64 bypasses the battery pack 44 and is provided to the traction bus 98 (represented by element 99).

[0059] In range assist mode, the auxiliary battery pack 62 is connected in series with the battery pack 44 and operates during propulsion to provide charge to the battery pack 44 to maintain the battery pack 44 at or above a desired SOC. In range assist mode, the auxiliary battery pack 62 provides power to the battery pack 44 via the DC-DC converter 64 to maintain the SOC of the battery pack 44 at a specific level. Current flows from the auxiliary battery pack 62 through the DC-DC converter 64 and into the battery pack 44.

[0060] As in Fig. As shown schematically in Figure 3B, in range assist mode, the traction battery pack 44 provides power to the traction bus 98, and the auxiliary battery pack 62 is connected in series with the battery pack 44 to supply charge to it when needed or requested. For example, when the controller 66 determines that the SOC of the battery pack 44 is below a certain threshold charge level, or when a request is received, power from the auxiliary battery pack 62 is caused to flow through the DC-DC converter 64, which can be controlled in this mode to adjust an output voltage, as described herein. The current from the DC-DC converter flows to the battery pack 44 and charges the battery pack 44.

[0061] Fig. 4 illustrates one embodiment of a method 100 for transferring power between and / or from battery systems with different chemistries. Aspects of the method 100 may be performed by one or more processors located within a vehicle, such as controller 66. It should be understood that the method 100 is not so limited and may be performed by any suitable processing device or system, or combination of processing devices.

[0062] The method 100 includes a number of steps or stages represented by blocks 101-108. The method 100 is not limited to the number or order of steps therein, as some steps represented by blocks 101-108 may be performed in a different order than that described below, or fewer than all of the steps may be performed.

[0063] The method 100 is used in conjunction with the vehicle 10 of Fig. 1 and the topology of Fig. 5 for illustrative purposes. The method 100 is not so limited and may be used with any suitable vehicle battery system and any suitable mixed-chemistry battery system.

[0064] At block 101, the processing device monitors the vehicle 10 and the amount of power requested by a driver. At block 102, the processing device determines whether the power demand exceeds a threshold. The power demand threshold may refer to a maximum power output or power limit of the battery pack 44 and / or the battery pack 46.

[0065] If the requested power exceeds the power demand threshold, the processing device determines the SOC of the auxiliary battery pack 62 at block 103. If the SOC of the auxiliary battery pack is above a minimum SOC value or an SOC threshold, the processing device places the mixed-chemistry battery system 40 into the power assist mode discussed above at block 104, and both battery packs 44 and 64 supply power to the drive. If the SOC of the auxiliary battery pack is at or below the minimum SOC or SOC threshold, the method returns to block 101.

[0066] If the requested power does not exceed the power demand threshold, the processing device determines the SOC of the battery pack 44 at block 105. At block 106, the SOC of the battery pack 44 is compared to an SOC threshold. If the SOC is at or above the SOC threshold, the method returns to block 101.

[0067] If the SOC of battery pack 44 is below the SOC threshold, the processing device compares the SOC of battery pack 62 to a selected threshold level at block 107. If the SOC of battery pack 62 is below the selected threshold level, the method returns to block 101.

[0068] If the SOC of battery pack 62 is at or above the selected threshold level, at block 108, the processing device places the mixed-chemistry battery system 40 into the range assist mode discussed above, in which the auxiliary battery pack 62 is connected in series with the battery pack. Energy is then transferred to the battery pack 44 until the battery pack reaches a desired SOC and / or is maintained at or above a target SOC of the battery pack 44.

[0069] As already mentioned, the mixed chemistry battery systems described here can be used to facilitate charging. Fig. Figure 5 illustrates the energy flow between the vehicle components during a charging process. The charging process is performed using a control method or algorithm that enables the simultaneous or concurrent charging of both a traction battery system and an auxiliary battery system.

[0070] In one embodiment, charging is performed based on prioritizing charging of the traction battery system so that the available power is provided to the traction battery, subject to charging constraints used to protect the traction battery pack(s). Any remaining power (i.e., power not required to charge the traction battery) is provided to charge the auxiliary battery system.

[0071] In Fig. 5, power flow and communication are schematically illustrated. The traction battery system is configured as a power module 110, which includes a traction battery assembly, such as battery pack 44, and at least one cell 54. A power module 112 includes an auxiliary battery assembly, such as auxiliary battery pack 62. At least one bidirectional DC-DC converter 114 (isolated or non-isolated) is connected between the power module 110 and the power module 112.

[0072] Controller 66 controls the power flow during charging. In one embodiment, controller 66 is a predictive controller that performs a model predictive control (MPC) method. MPC is based on a model of the propulsion system and the auxiliary battery system and is selected so that controller 66 can simulate the system parameters and make predictions used to control the charging process.

[0073] During the charging process, the battery pack 62 and the battery pack 44 are connected to the charging bus 80, and a charging current ic is supplied to the charging bus 80. The charging current is adjusted based on control signals provided by the controller 66.

[0074] In one embodiment, a heat source is used to enable heating of the power module 112 to improve charging performance. This is useful in environments such as low temperatures or during certain times of the year. For example, chemistries such as LMB are better suited to accepting higher charging rates when the cells are warm (e.g., at or above approximately 50 degrees Celsius). The power module 110 can be used to provide energy to heat the cells in the power module 112, or a separate heating device can be used to heat the power module 112.

[0075] In one embodiment, the power module 110 is configured to heat the energy module 112 by applying an alternating heating current ih is applied to it. The heating current is controlled by a controller 118. The heating current ih can be used to increase the temperature of the energy module 112 so that the cells therein can be charged at a higher charging rate.

[0076] During a charging session, current, voltage, and temperature measurements are taken at modules 110 and 112. Controller 66 generates or acquires estimates of the SOC (referred to as SOCe) and state of power (SOP) for energy module 112 and also generates or acquires estimates of the SOC (referred to as SOCp) and state of power (SOP) for power module 110. The estimates are based on the charging current and the measured voltages and temperatures.

[0077] In one embodiment, the SOC and SOP estimates are predictions used by the controller 116 in real time to determine a desired charging current ic The predictions are captured by applying measurements to a mathematical model that simulates the parameters of the energy module 112 and the power module 110. The predictions are used by the controller using model predictive control (MPC) to determine an optimal value for the charging current. The optimal value is a value that results from minimizing a cost function while simultaneously satisfying constraints.

[0078] In one embodiment, the mathematical model is a quasi-steady-state model that simulates the SOC and temperature of the modules. Embodiments are not so limited, as other types of models may also be used. Examples of such models include steady-state models and lookup-table-based models.

[0079] The following equations represent an example of a quasi-stationary model: qe(t+ΔT)=qe(t)−1QepiL(t)ΔT+1Qpic(t)ΔT qp(t+ΔT)=qp(t)+1QppiL(t)Ve(t)Vp(t)ΔT−1Qpih(t)ΔT T(t+ΔT)=(1−ΔTmbCpbhA)T(t)+ΔTmbCpbhATamb+ΔTmbCpbVp(t)ih(t)

[0080] In the above equations, t represents time and ΔT represents a change in the temperature of the energy module 112 compared to a previous time step or prediction. ic stands for the charging current, i L for the current through the inductance Linput and i hstands for the heating current. q e stands for the SOC of the energy module 112, q e stands for the SOC of the energy module 112, and T stands for the temperature of the energy module 112. Q e and Q p represent the respective capacities of the energy module 112 and the power module 110.

[0081] p is a variable that refers to each phase of the AC power supplied to the drive and is defined as the number of DC-DC converters 114 connected in parallel. mb is the mass of the power module 112. Cp b stands for the specific heat, h stands for the heat transfer coefficient, and A for the surface area. V e and V p represent the voltage of the energy module 112 or the power module 110.

[0082] q e (t) represents q e in a given time step or time, and qe (t + ΔT) represents a prediction of q ein view of the temperature change. Similarly, q p (t) q p at time t and q e (t + ΔT) represents a prediction of q p and T (t + ΔT) represents a prediction for the temperature of the energy module 112.

[0083] The control device 66 controls the charging current, the inductance current and the heating current (if used) to keep these currents within the following limits: 0≤iL(t),0≤ih(t),0≤ic(t) −iEnergymax(T)1p≤iL(t)−1pic(t)≤−iEnergymin(T)1p, iPowerminV2(t)pV1(t)≤iL(t)+V2(t)pV1(t)ih(t)≤iPowermaxV2(t)pV1(t), where imaxEnergy(T) and iminEnergy(T) a maximum permissible current and a minimum current through the energy module 112 at a temperature T. imaxPower and iminPower a maximum permissible current and a minimum current through the power module 110.

[0084] To keep the system performance within these limits, the controller determines 66 values ​​of the currents that minimize a cost function J: J=∑k=1N(y(k)+Ru(k)), where y(k)=w1(qe(k)−1)2+w2(qp(k)−1)2 Ru(k)=w2iL2+w4ih2+w5ic2

[0085] Here, k is a time step or a control interval and N is a chosen finite horizon (e.g., the number of consecutive intervals k). w1 and w2 are weighting coefficients for q e or q p . w3, w4 and w5 are weighting coefficients for i L , i h and i c . The weights can be selected to adjust the importance or weight given to each parameter in optimizing the different streams.

[0086] Fig. 6 illustrates one embodiment of a method 120 for charging a battery system of a vehicle. Aspects of the method 120 may be performed by one or more processors located within a vehicle, such as a battery management system (BMS) controller. It should be understood that the method 120 is not so limited and may be performed by any suitable processing device or system, or combination of processing devices.

[0087] The method 120 includes a number of steps or stages represented by blocks 121-125. The method 120 is not limited to the number or order of steps therein, as some steps represented by blocks 121-125 may be performed in a different order than that described below, or fewer than all of the steps may be performed.

[0088] For illustrative purposes, the method 120 is described in connection with the vehicle 10 of Fig. 1, the battery system 40 with mixed chemistry from Fig. 2 and the schematic representation of Fig. 5. The method 120 is not so limited and may be used with any suitable vehicle battery system and any suitable charging system.

[0089] At block 121, a charging process is initiated. The charging process may be initiated by placing the vehicle 10 into a charging mode and connecting the charging port 68 to a power source. The power source may be a charging station, a power grid, another vehicle, or another suitable energy source. The controller may communicate with the power source, for example, via a charging cable or wirelessly.

[0090] The controller determines various charging parameters such as the nominal battery voltage of the power module 110 and the energy module 112, the initial temperature, the maximum permissible charging current and the desired charging energy.

[0091] At block 122, the controller inputs charging parameters into a mathematical model of the components used in the charging process. In one example, the mathematical model is a quasi-steady-state model, as discussed above, or any other suitable model that allows for simulation, prediction, or estimation of the state of charge, temperature, and / or other parameters or conditions of the modules.

[0092] At block 123, a charging current i capplied to the power module 110. During charging, current, voltage, and temperature measurements are taken from the modules and provided to the model. The measurements can be performed continuously or periodically at a variety of consecutive sampling times or time steps.

[0093] At block 124, the controller applies the measurements at each time step to the model to predict the state of charge of the power module 110. The controller then determines an optimal charging current that remains within selected limits and minimizes a cost function as described herein.

[0094] The controller periodically controls the charging current to adjust it to the optimal charging current.

[0095] At block 125, when the predicted or estimated state of charge reaches a desired level, the controller disconnects the power module 110 from the charging bus 80 or otherwise ceases providing power to charge the power module 110. The power module 112 is then charged for a selected period of time, or until the power module 112 reaches a desired SOC. While charging the power module 112, the controller continues to measure the battery parameters and determines an optimal charging current by minimizing a cost function, as described herein.

[0096] In one embodiment, the power module 110 and the energy module 112 are charged simultaneously. For example, the DC-DC converter 64 is a partial power processor, or the mixed-chemistry battery system otherwise includes components that allow portions of the total charging power to be allocated to the energy module and the power module. In this embodiment, the controller determines the amount of power needed to charge the power module 110 and directs that amount of power to the power module 110. The remaining power is directed to the energy module 112.

[0097] The various battery systems described herein may be packaged or arranged in any suitable manner. In one embodiment, the battery systems (e.g., as part of a battery module or power module) are arranged to distribute the temperature such that the temperature of a given cell or module does not exceed a desired threshold.

[0098] Fig. 7 shows an example of a hybrid battery pack 130 that includes multiple cells with different chemistries. In this example, the hybrid battery pack includes LFP cells 132 (e.g., cells of battery pack 44 and / or 46) and NCM cells 134 (e.g., cells 54 of Fig. 1). The battery pack also includes the LMB cells 136, which are cells of the battery pack 62 of Fig. 1 can act.

[0099] In this example, the temperature is distributed according to a pattern that evenly distributes the different chemistries. In one embodiment, the pattern is chosen so that individual cells with the same chemistry are not adjacent to each other. Fig. The pattern shown in Figure 7 is an example, as other distribution patterns can also be used for different cell chemistries. In some cases, it may be preferable to incorporate thermal barriers.

[0100] Fig. Figure 8 illustrates aspects of one embodiment of a computer system 140 that can perform various aspects of the embodiments described herein. Computer system 140 includes at least one processing device 142, generally including one or more processors for performing aspects of the image acquisition and analysis methods described herein.

[0101] Components of computer system 140 include processing device 142 (such as one or more processors or processing units), memory 144, and a bus 146 that couples various system components, including system memory 144, to processing device 142. System memory 144 may be a non-transitory, computer-readable medium and may include a variety of computer-readable media. These media may be any available media accessible by processing device 142 and include both volatile and non-volatile media, as well as removable and non-removable media.

[0102] System memory 144 includes, for example, non-volatile memory 148, such as a hard drive, and may also include volatile memory 150, such as random access memory (RAM) and / or cache memory. Computer system 140 may further include other removable / non-removable, volatile / non-volatile computer system storage media.

[0103] The system memory 144 may include at least one program product having a set (e.g., at least one) of program modules configured to perform the functions of the embodiments described herein.

[0104] For example, system memory 144 stores various program modules that generally perform the functions and / or methodologies of the embodiments described herein. One or more modules 152 may be included to perform functions related to controlling power transfer as described herein. System 140 is not so limited, as other modules may be included. As used herein, the term "module" refers to processing circuitry, which may include an application-specific integrated circuit (ASIC), an electronic circuit, a processor (common, dedicated, or group), and memory executing one or more software or firmware programs, combinational logic circuitry, and / or other suitable components that provide the described functionality.

[0105] Processing device 142 may also communicate with one or more external devices 156, such as a keyboard, a pointing device, and / or other devices (e.g., a network card, a modem, etc.) that enable processing device 142 to communicate with one or more other computing devices. Communication with various devices may occur via input / output (I / O) interfaces 164 and 165.

[0106] Processing device 142 may also communicate with one or more networks 166, such as a local area network (LAN), a general purpose wide area network (WAN), a bus network, and / or a public network (e.g., the Internet), via a network adapter 168. It should be understood that other hardware and / or software components may also be used in connection with computer system 140, even if not depicted. Examples include, but are not limited to: microcode, device drivers, redundant processing units, external hard disk arrays, RAID systems, data archiving systems, etc.

[0107] The terms "a" and "an" do not imply a limitation of quantity, but rather denote the presence of at least one of the recited items. The term "or" means "and / or" unless the context clearly indicates otherwise. References throughout this specification to "an aspect" mean that a particular element (e.g., a feature, structure, step, or property) described in connection with that aspect is included in at least one of the aspects described herein and may or may not be present in other aspects. Furthermore, it is to be understood that the described elements in the various aspects may be combined in any suitable manner.

[0108] When an element, such as a layer, film, region, or substrate, is described as being "on" another element, it may be directly on top of the other element, or there may be intervening elements. Conversely, when an element is described as being "directly on" another element, there are no intervening elements.

[0109] Unless otherwise indicated herein, all examination standards are the most recent standard in effect on the filing date of this application or, if priority is claimed, the filing date of the earliest priority application in which the examination standard appears.

[0110] Unless otherwise defined, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0111] While the above disclosure has been described with reference to exemplary embodiments, it will be appreciated by those skilled in the art that various changes may be made and equivalent elements may be substituted without departing from its scope. Furthermore, many changes may be made to adapt a particular situation or material to the teachings of the disclosure without departing from its essential scope. Therefore, the present disclosure is not intended to be limited to the particular embodiments disclosed, but is intended to include all embodiments falling within its scope.

Claims

[1] Power transmission control system comprising: a traction battery assembly configured to power an electric motor of a vehicle, the traction battery assembly having a first chemistry; an auxiliary battery assembly selectively connected to the traction battery assembly, the auxiliary battery assembly having a second chemistry different from the first chemistry; and a controller configured to selectively connect the auxiliary battery assembly to perform at least one of: providing electrical charge to the traction battery assembly and supplying electrical power to the electric motor. [2] The system of claim 1, further comprising a third battery assembly comprising a battery cell having a third chemistry different from the first and second chemistry, the battery cell being connected in series with the traction battery assembly. [3] The system of claim 1, wherein the auxiliary battery assembly is a high energy battery assembly having an energy density greater than the energy density of the traction battery assembly. [4] The system of claim 1, further comprising a DC-DC converter connected in parallel with the traction battery assembly and the auxiliary battery assembly, the DC-DC converter being configured to adjust an output voltage of the auxiliary battery assembly, the controller being configured to connect the auxiliary battery assembly in series with the traction battery assembly and to supply the electrical charge to the traction battery assembly via the DC-DC converter during vehicle propulsion to increase the range of the vehicle. [5] The system of claim 4, wherein the controller is configured to connect the auxiliary battery assembly based on a state of charge (SOC) of the traction battery assembly being below a SOC threshold and to provide the electrical charge to maintain the SOC of the traction battery assembly at or above the SOC threshold. [6] The system of claim 1, further comprising a DC-DC converter connected in parallel with the traction battery assembly and the auxiliary battery assembly, the DC-DC converter being configured to adjust an output voltage of the auxiliary battery assembly, the controller being configured to connect the auxiliary battery assembly in parallel with the traction battery assembly and to supply electrical power to the electric motor via the DC-DC converter, the electrical power bypassing the traction battery assembly. [7] The system of claim 1, wherein the vehicle is configured to be connected to a power source for charging the traction battery assembly, and the controller is configured to control a charging process that prioritizes the provision of charging power to the traction battery assembly. [8] The system of claim 7, wherein the charging operation comprises providing an amount of power to charge the traction battery assembly to a desired SOC and providing a remaining amount of power to charge the auxiliary battery assembly. [9] The system of claim 7, wherein the controller is configured to control the charging process based on a predictive control methodology that includes predicting a state of charge of the traction battery assembly and the auxiliary battery assembly based on a quasi-steady-state model. [10] A method for controlling power transmission, comprising: Monitoring a propulsion system of a vehicle by a controller, the propulsion system connected to a mixed chemistry battery system, the mixed chemistry battery system comprising a propulsion battery assembly configured to power an electric motor of the propulsion system and an auxiliary battery assembly selectively connected to the propulsion battery assembly, the propulsion battery assembly having a first chemistry and the auxiliary battery assembly having a second chemistry different from the first chemistry; based on receiving a request for additional propulsion, connecting the auxiliary battery assembly and supplying additional power to the electric motor; and based on a state of charge (SOC) of the traction battery assembly being below a SOC threshold, providing electrical charge to the traction battery assembly from the auxiliary battery assembly.

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