Voltage control of multi-battery systems

Abstract

A system for controlling propulsion in a vehicle includes a switching system connected to a battery system, which is connected via a propulsion bus to a drive unit and one or more electrical loads. A controller is configured to control the switching system to change the voltage applied to the drive unit. The controller is configured to receive a request to switch between operating modes, the switching including changing the voltage applied to the drive unit from an initial voltage level to a target voltage level. The controller is configured to sequentially perform: deactivating one or more electrical loads; pre-charging one or more electrical loads based on a target voltage higher than the initial voltage; performing a discharge process based on a target voltage lower than the initial voltage; and operating the switching system to apply voltage at the target voltage level.

Description

Technical Field

[0001] The present invention relates to vehicles, and more specifically, to the voltage of one or more electric drives controlling a vehicle. Background Technology

[0002] Vehicles, including gasoline and diesel-powered vehicles, as well as electric and hybrid electric vehicles, have battery storage for purposes such as powering electric motors, electronics, and other vehicle subsystems. Some vehicles have multi-drive systems that include two or more electric motors for applying torque. For example, some vehicles include a drive system for controlling the torque applied to the rear wheels and another drive system for controlling the torque applied to the front wheels. Summary of the Invention

[0003] In one exemplary embodiment, a system for controlling propulsion in a vehicle includes a switching system connected to a battery system comprising a first battery assembly and a second battery assembly selectively connected to a drive unit and one or more electrical loads via a propulsion bus. The switching system includes a first switching device configured to selectively connect the first battery assembly to the propulsion bus, a second switching device configured to selectively connect the second battery assembly to the propulsion bus, and a third switching device configured to selectively connect the first battery assembly to the second battery assembly. The system also includes a controller configured to control the switching system to change the voltage applied to the drive unit during vehicle propulsion. The controller is configured to receive a request to switch from a first operating mode to a second operating mode, the switching including changing the voltage applied to the drive unit from an initial voltage level to a target voltage level. The controller is configured to sequentially perform: deactivating one or more electrical loads; pre-charging one or more electrical loads based on a target voltage higher than the initial voltage; performing a discharge process to discharge a capacitor in each of the one or more electrical loads based on a target voltage lower than the initial voltage; and operating the switching system to apply voltage to the drive unit at the target voltage level.

[0004] In addition to one or more features described herein, the switching system operates to connect the first battery assembly in series to the second battery assembly based on a target voltage level higher than an initial voltage level, and the switching system operates to connect the first battery assembly in parallel to the second battery assembly based on a target voltage level lower than an initial voltage level.

[0005] In addition to one or more features described herein, the first switching device includes a first pair of switches for selectively connecting the first battery assembly to the propulsion bus, and the second switching device includes a second pair of switches for selectively connecting the second battery assembly to the propulsion bus.

[0006] In addition to one or more features described herein, the switching system includes a precharge circuit having a first precharge switch connected to a first battery assembly and a second precharge switch connected to a second battery assembly.

[0007] In addition to one or more features described herein, the target voltage is higher than the initial voltage, and in the first operating mode, the first pair of switches is closed, the second pair of switches is closed, the third switching device is open, the first precharge switch and the second precharge switch are open, and the first battery assembly is connected in parallel to the second battery assembly. Precharging includes opening the first pair of switches and one of the second pair of switches, closing the third switching device to connect the first battery assembly in series to the second battery assembly, closing the first precharge switch and precharging one or more electrical loads to the target voltage level, and after the one or more electrical loads are at the target voltage level, opening the first precharge switch and closing one of the second pair of switches.

[0008] In addition to one or more features described herein, the target voltage is lower than the initial voltage, and in the first operating mode, one of the first pair of switches is open and the other of the first pair of switches is closed, one of the second pair of switches is open and the other of the second pair of switches is closed, the third switching device is closed, and the first battery assembly is connected in series to the second battery assembly via the third switching device.

[0009] In addition to one or more features described herein, discharging includes deactivating one or more electrical loads, disconnecting a third switching device, disconnecting another of the first pair of switches, closing one of the first pair of switches, discharging one or more electrical loads to a target voltage level, monitoring the voltage during discharge, comparing the difference between the monitored voltage and the target voltage, and based on the difference being less than a threshold difference, closing one of the second pair of switches and closing the other of the first pair of switches to connect the first battery assembly in parallel to the second battery assembly.

[0010] In addition to one or more features described herein, the one or more electrical loads include multiple electrical loads. Discharging includes deactivating the multiple electrical loads, disconnecting the third switching device, disconnecting another of the first pair of switches, activating one of the multiple electrical loads and closing one of the first pair of switches, discharging the multiple electrical loads to a target voltage level through the activated load, monitoring the voltage during discharge and comparing the difference between the monitored voltage and the target voltage, and based on the difference being less than a threshold difference, closing one of the second pair of switches and closing the other of the first pair of switches to connect the first battery assembly in parallel to the second battery assembly, and reactivating the multiple electrical loads.

[0011] In addition to one or more features described herein, the switching system includes a pre-charge circuit having a first pre-charge switch connected to the first battery assembly and a second pre-charge switch connected to the battery assembly. Discharging includes disconnecting a third switching device, disconnecting another of the first pair of switches, closing the second pre-charge switch and closing one of the first pair of switches, discharging one or more electrical loads to a target voltage level via a resistor connected to the second pre-charge switch, monitoring the voltage during discharge and comparing the difference between the monitored voltage and the target voltage, and based on the difference being less than a threshold difference, closing one of the second pair of switches, disconnecting the second pre-charge switch, and closing the other of the first pair of switches to connect the first battery assembly in parallel to the second battery assembly.

[0012] In one exemplary embodiment, a method of controlling vehicle propulsion includes receiving a request to switch from a first operating mode to a second operating mode, the switching including changing the voltage applied to a drive unit of the vehicle from an initial voltage level to a target voltage level. The vehicle includes a switching system connected to a battery system comprising a first battery assembly and a second battery assembly selectively connected to the drive unit and one or more electrical loads via a propulsion bus. The switching system includes a first switching device configured to selectively connect the first battery assembly to the propulsion bus, a second switching device configured to selectively connect the second battery assembly to the propulsion bus, and a third switching device configured to selectively connect the first battery assembly to the second battery assembly. The method further includes: deactivating one or more electrical loads; pre-charging one or more electrical loads based on a target voltage higher than an initial voltage; performing a discharge process to discharge a capacitor in each of the one or more electrical loads based on a target voltage lower than an initial voltage; and operating the switching system to apply a voltage to the drive unit at the target voltage level.

[0013] In addition to one or more features described herein, the operating switch system includes connecting the first battery assembly in series to the second battery assembly based on a target voltage level being higher than an initial voltage level, or connecting the first battery assembly in parallel to the second battery assembly based on a target voltage level being lower than an initial voltage level.

[0014] In addition to one or more features described herein, the first switching device includes a first pair of switches for selectively connecting the first battery assembly to the propulsion bus, and the second switching device includes a second pair of switches for selectively connecting the second battery assembly to the propulsion bus.

[0015] In addition to one or more features described herein, the switching system includes a pre-charge circuit having a first pre-charge switch connected to a first battery assembly and a second pre-charge switch connected to a second battery assembly. A target voltage is higher than an initial voltage, and in a first operating mode, the first pair of switches is closed, the second pair of switches is closed, the third switching device is open, the first and second pre-charge switches are open, and the first battery assembly is connected in parallel to the second battery assembly. Pre-charging includes opening the first pair of switches and one of the second pair of switches, closing the third switching device to connect the first battery assembly in series to the second battery assembly, closing the first pre-charge switch and pre-charging one or more electrical loads to the target voltage level, and after the one or more electrical loads are at the target voltage level, opening the first pre-charge switch and closing one of the second pair of switches.

[0016] In addition to one or more features described herein, the target voltage is lower than the initial voltage, and in the first operating mode, one of the first pair of switches is open and the other of the first pair of switches is closed, one of the second pair of switches is open and the other of the second pair of switches is closed, the third switching device is closed, and the first battery assembly is connected in series to the second battery assembly via the third switching device.

[0017] In addition to one or more features described herein, discharging includes deactivating one or more electrical loads, disconnecting a third switching device, disconnecting another of the first pair of switches, closing one of the first pair of switches, discharging one or more electrical loads to a target voltage level, monitoring the voltage during discharge and comparing the difference between the monitored voltage and the target voltage, and based on the difference being less than a threshold difference, closing one of the second pair of switches and closing the other of the first pair of switches to connect the first battery assembly in parallel to the second battery assembly.

[0018] In addition to one or more features described herein, the one or more electrical loads include multiple electrical loads, and discharging includes deactivating multiple electrical loads, disconnecting a third switching device, disconnecting another of the first pair of switches, activating one of the multiple electrical loads and closing one of the first pair of switches, discharging the multiple electrical loads to a target voltage level through the activated load, monitoring the voltage during discharge, comparing the difference between the monitored voltage and the target voltage, and based on the difference being less than a threshold difference, closing one of the second pair of switches and closing the other of the first pair of switches to connect the first battery assembly in parallel to the second battery assembly, and reactivating the multiple electrical loads.

[0019] In addition to one or more features described herein, the switching system includes a pre-charge circuit having a first pre-charge switch connected to the first battery assembly and a second pre-charge switch connected to the battery assembly. Discharging includes disconnecting a third switching device, disconnecting another of the first pair of switches, closing the second pre-charge switch and closing one of the first pair of switches, discharging the electrical load to a target voltage level through a resistor connected to the second pre-charge switch, monitoring the voltage during discharge and comparing the difference between the monitored voltage and the target voltage, and based on the difference being less than a threshold difference, closing one of the second pair of switches, disconnecting the second pre-charge switch and closing the other of the first pair of switches to connect the first battery assembly in parallel to the second battery assembly.

[0020] In one exemplary embodiment, a vehicle system includes a memory having computer-readable instructions and a processing means for executing the computer-readable instructions, which control the processing means to perform a method. The method includes receiving a request to switch from a first operating mode to a second operating mode, the switch including changing a voltage applied to a vehicle drive unit from an initial voltage level to a target voltage level. The vehicle includes a switching system connected to a battery system including a first battery assembly and a second battery assembly selectively connected to the drive unit and one or more electrical loads via a propulsion bus. The switching system includes a first switching device configured to selectively connect the first battery assembly to the propulsion bus, a second switching device configured to selectively connect the second battery assembly to the propulsion bus, and a third switching device configured to selectively connect the first battery assembly to the second battery assembly. The method further includes: deactivating one or more electrical loads; pre-charging one or more electrical loads based on a target voltage higher than an initial voltage; performing a discharge process to discharge a capacitor in each of the one or more electrical loads based on a target voltage lower than an initial voltage; and operating the switching system to apply a voltage to the drive unit at the target voltage level.

[0021] In addition to one or more features described herein, the operating switch system includes connecting the first battery assembly in series to the second battery assembly based on a target voltage level being higher than an initial voltage level, or connecting the first battery assembly in parallel to the second battery assembly based on a target voltage level being lower than an initial voltage level.

[0022] In addition to one or more features described herein, the first switching device includes a first pair of switches for selectively connecting the first battery assembly to the propulsion bus, and the second switching device includes a second pair of switches for selectively connecting the second battery assembly to the propulsion bus.

[0023] The above-described features and advantages, as well as other features and advantages, of this disclosure will become apparent from the following detailed description when taken in conjunction with the accompanying drawings. Attached Figure Description

[0024] Other features, advantages, and details appear only by way of example in the following detailed description, which refers to the accompanying drawings, wherein:

[0025] Figure 1 This is a top view of a motor vehicle according to an exemplary embodiment, the motor vehicle including a battery system having two independent battery packs or two halves of a single battery pack, and a switching system for controlling the switching between operating modes;

[0026] Figure 2 A vehicle system according to an exemplary embodiment is shown, the vehicle system including a plurality of drive units, a battery system having two independent battery packs or two halves of a single battery pack, and a switching system including independently operable switching devices for applying variable voltage;

[0027] Figure 3 It is a flowchart describing various aspects of a method for activating a vehicle operation mode according to an exemplary embodiment;

[0028] Figure 4 This is a flowchart describing aspects of a method for switching between operating modes of a vehicle according to an exemplary embodiment, wherein the operating modes are related to different voltage levels applied to the vehicle drive system and electrical loads;

[0029] Figure 5 This is a flowchart depicting aspects of a method for increasing the voltage level applied to a vehicle drive system and an electrical load according to an exemplary embodiment, the method including a pre-charging process for limiting inrush current;

[0030] Figure 6 This is a flowchart depicting aspects of a method for reducing voltage levels applied to a vehicle drive system and electrical loads according to an exemplary embodiment, the method including a passive discharge process for limiting inrush current;

[0031] Figure 7 This is a flowchart describing aspects of a method for reducing voltage levels applied to a vehicle drive system and electrical loads according to an exemplary embodiment, the method including performing an active discharge process using a pre-charge circuit;

[0032] Figure 8 This is a flowchart describing aspects of a method for reducing voltage levels applied to a vehicle drive system and an electrical load according to exemplary embodiments, the method including performing an active discharge process using the electrical load; and

[0033] Figure 9 A computer system according to an exemplary embodiment is described. Detailed Implementation

[0034] The following description is exemplary in nature only and is not intended to limit this disclosure, its application, or use. It should be understood that in all the drawings, corresponding reference numerals denote the same or corresponding parts and features.

[0035] According to exemplary embodiments, methods, apparatus, and systems are provided for controlling vehicle propulsion and switching between vehicle operating modes associated with different voltage levels. The vehicle includes a drive system comprising a single drive system or drive unit, or multiple drive systems or drive units. In one embodiment, the vehicle includes a battery system having at least a first battery assembly and a second battery assembly. For example, the first battery assembly includes a first battery pack, and the second battery assembly includes a second battery pack. In another example, if the battery system includes a single battery pack (e.g., a single battery pack having two halves), then the first and second battery assemblies may each be part of the battery pack (e.g., one of the two halves).

[0036] The vehicle includes a battery system and a switching system having independently controllable switching devices that can be operated by a controller to change the voltage levels applied to the drive system and any electrical components (i.e., loads) receiving power from the battery system. When the vehicle is stationary (e.g., during startup), the switching devices can be controlled to initiate a desired operating mode, and when the propulsion system is active (e.g., during driving), the switching devices can be controlled to switch the vehicle between various operating modes. In one embodiment, the operating modes are associated with different voltage levels. For example, the switching system includes one or more switches (“series switches”) operable to connect the first and second battery packs in series to provide a relatively high voltage. The switching system also includes one or more switches (“parallel switches”) operable to connect the first and second battery packs in parallel to provide a relatively low voltage.

[0037] Embodiments of the system include a controller (or other processing device) configured to use a sequential switching process to control the transition between operating modes, ensuring efficient transitions without damaging or negatively impacting electrical components connected to the battery system. The switching process includes deactivating electrical loads connected to the battery system, performing pre-charge or discharge processes to limit or prevent inrush current during transitions, and operating the switching system to increase or decrease the voltage applied to the propulsion system and electrical loads based on target voltage levels.

[0038] This switching process ensures that electrical components (including drive system inverters and other electrical loads) do not draw current from or push current into the battery system during switching, and also ensures that capacitors in the electrical components are pre-charged or discharged to avoid any significant inrush current during switching.

[0039] Note that "low voltage" and "high voltage" are relative terms and are not intended to limit voltage levels to specific values ​​or ranges. For example, embodiments are described here in conjunction with a low voltage of 400V or 600V and a high voltage of 800V; however, low voltage and high voltage can be any desired or suitable voltage level or range.

[0040] The embodiments are not limited to use with any particular vehicle and can be applied to a variety of environments. For example, the embodiments can be used in automobiles, trucks, aircraft, construction equipment, farm equipment, automated factory equipment, and / or any other equipment or system that includes multiple drives and / or multiple conversion devices.

[0041] Figure 1 An embodiment of a motor vehicle 10 is shown, which includes a body 12 that at least partially defines a passenger compartment 14. The body 12 also supports various vehicle subsystems, including a propulsion system 16 and other subsystems to support the functions of the propulsion system 16 and other vehicle components, such as a braking subsystem, a suspension system, a steering subsystem, etc.

[0042] Vehicle 10 may be an electric vehicle (EV), a hybrid vehicle, or any other vehicle. In one embodiment, vehicle 10 is an electric vehicle that includes multiple motors and / or drive systems. Any number of drive units may be included, such as one or more drive units for applying torque to the front wheels (not shown) and / or the rear wheels (not shown). The drive units are controllable to operate vehicle 10 in various operating modes, such as normal mode, high-performance mode (where additional torque is applied), all-wheel drive (“AWD”), front-wheel drive (“FWD”), rear-wheel drive (“RWD”), etc.

[0043] For example, propulsion system 16 is a multi-drive system, comprising a front drive unit 20 for driving the front wheels and a rear drive unit for driving the rear wheels. The front drive unit 20 includes a front electric motor 22 and a front inverter 24 (e.g., a front power inverter module or FPIM), as well as other components such as a cooling system. The left rear drive unit 30L includes an electric motor 32L and an inverter 34L. The right rear drive unit 30R includes an electric motor 32R and an inverter 34R. Inverters 24, 34L, and 34R (e.g., power inverter units or PIMs) each convert DC power from the high-voltage (HV) battery system 40 into multiphase (e.g., two-phase, three-phase, six-phase, etc.) alternating current (AC) power to drive motors 22 and 32L and 32R.

[0044] like Figure 1 As shown, the drive system has an independent electric motor. However, the embodiments are not limited to this. For example, instead of separate motors, multiple drives can be provided by a single motor with multiple sets of physically independent windings.

[0045] Similarly, Figure 1 As shown, the drive system is configured such that the front electric motor 22 drives the front wheels (not shown), and the rear electric motors 32L and 32R drive the rear wheels (not shown). However, the embodiment is not limited to this, as any number of drive systems and / or motors can be present in different locations (e.g., one motor driving each wheel, dual motors per axle, etc.). Furthermore, the embodiment is not limited to a dual drive system, as it can be used in vehicles with any number of motors and / or power inverters.

[0046] In the propulsion system 16, drive units 20, 30L, and 30R are electrically connected to the battery system 40. The battery system 40 may also be electrically connected to other electrical components (also referred to as “electrical loads”), such as vehicle electronics (e.g., via an auxiliary power module or APM42), heaters, cooling systems, etc. The battery system 40 may be configured as a rechargeable energy storage system (RESS).

[0047] In one embodiment, the battery system 40 includes multiple independent battery components, each of which can be charged independently and can be used to independently power one or more drive systems. For example, the battery system 40 includes first battery components, such as a first battery pack 44 connected to the inverter 24, and a second battery pack 46. Battery pack 44 includes multiple battery modules 48, and battery pack 46 includes multiple battery modules 50. Each module 48, 50 includes multiple individual batteries (not shown).

[0048] Each of the front motor 22 and the rear motors 32L and 32R is a three-phase motor with three-phase motor windings. However, the embodiments described herein are not limited to this. For example, the motor can be any multiphase motor powered by a multiphase inverter, and the drive unit can be implemented using a single motor with independent sets of windings.

[0049] Battery system 40 and / or propulsion system 16 include a switching system with various switching devices for controlling the operation of battery packs 44 and 46 and selectively connecting battery packs 44 and 46 to drive systems 20, 30L, and 30R. The switching devices may also be operable to selectively connect battery packs 44 and 46 to a charging system. The charging system can be used to charge battery packs 44 and 46, and / or to supply power from battery packs 44 and / or 46 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 charging modules. For example, a first on-board charging module (OBCM) 52 is electrically connected to charging port 54 for charging and receiving from an AC system or device, such as a public AC power source. A second OBCM 53 may be included for DC charging (e.g., DC fast charging or DCFC).

[0050] In one embodiment, the switching system includes a first switching device 60 that selectively connects battery pack 44 to inverters 24, 34L, and 34R, and a second switching device 62 that selectively connects battery pack 46 to inverters 24, 34L, and 34R. The switching system also includes a third switching device 64 (also referred to as a "battery switching device") for selectively connecting battery pack 44 in series to battery pack 46.

[0051] Any different controller can be used to control the functions of the battery system 40, the switching system, and the drive unit. The controller includes any suitable processing device or unit, and existing controllers such as drive system controllers, RESS controllers, and / or controllers within the drive system can be used. For example, a controller 65 may be included for controlling the switching and drive control operations discussed herein.

[0052] Vehicle 10 also includes a computer system 55, which includes one or more processing units 56 and a user interface 58. The computer system 55 can communicate with the charging system controller, for example, by providing commands to it in response to user input. Various processing devices, modules, and units can communicate with each other via communication devices or systems, such as a Controller Area Network (CAN) or Transmission Control Protocol (TCP) bus.

[0053] Figure 2 Embodiments of the switching system are depicted, including switching devices 60, 62, and 64. The embodiments are discussed in conjunction with vehicle 10 and its dual-drive system. The embodiments are not limited thereto, as they can be used in any suitable vehicle system having multiple (i.e., two or more) drive units and battery packs.

[0054] Each switch described herein can be a mechanical contactor (such as a solenoid-controlled mechanical contactor), or a solid-state or electronic device. For example, Figure 2 The embodiments depict switching devices 60, 62, and 64 as switches configured as mechanical contactors. However, one or more switches may be electronic switches. Each switching device 60, 62, and 64 may be integrated into the battery system circuitry or included as a single device or removable module.

[0055] Any suitable solid-state or electronic device can be used as a switch. For example, switching devices 60, 62, and 64 may include solid-state relays and 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 can be used include power switching devices based on diamond, gallium oxide, and other wide-bandgap (WBG) semiconductors.

[0056] In one embodiment, the switching system is controllable to provide varying voltages to inverters 24, 34L, and / or 34R. In one embodiment, the switching system is controllable to apply a first voltage (“low voltage”) to the motor, or to apply a second voltage (“high voltage”), as discussed further herein. For example, the switching system can be controlled to apply a nominal or average voltage of 400V or 600V in a “low voltage” mode, or a nominal or average voltage of 800V in a “high voltage” mode. Note that there can be more than two battery packs with at least one switch between adjacent battery packs; in this case, the batteries can be interconnected in various ways to provide more than two voltages. Furthermore, there can be a single battery pack with multiple sections (e.g., a single battery with switches separating parallel battery strings); in this case, the switching system can be used to apply different voltages by connecting the strings in various ways.

[0057] As shown in the figure, the front inverter 24, the left rear inverter 34L (left power inverter module or LPIM), the right rear inverter 34R (right power inverter module or RPIM), battery pack 44, and battery pack 46 are connected in parallel to the propulsion DC bus 66. Additional components can be connected to the propulsion bus 66 to provide AC power to various electrical loads. Loads may include electrical components such as electronic devices, as well as heating and cooling systems (e.g., cabin heaters, cooling systems, etc.).

[0058] For example, the loads include an air conditioning electric compressor (ACEC) 68 and an integrated power electronics module (IPEO) 70. These loads are connected in parallel to the push bus 66, as shown. The loads may also include a resistor 72 to limit and dissipate current when switching between push mode and operating mode, as discussed further herein.

[0059] For charging and receiving power from vehicle 10, OBCM 53 is connected to charging port 54 via propulsion bus 66 to allow charging of vehicle 10 from charging stations (e.g., DCFC station 74). OBCM 53 includes switches 57 (OB1) and 59 (OB2) that allow OBCM 53 to connect to and disconnect from propulsion bus 66. OBCM 52 is connected to propulsion bus 66 via OBCM 53 and to charging port 54 via AC bus 76 for receiving power or supplying power to AC device 78.

[0060] The battery switching device 64 includes at least one switch (also referred to as a “series switch”) operable to connect and disconnect battery packs 44 and 46 in series with each other. The battery switching device 64 may include two switches 80 (SE1) and 82 (SE2) as shown, or may include a single switch. As discussed further herein, switch 80 (SE1) and / or switch 82 (SE2) may be operable to connect battery packs 44 and 46 in series to provide a selected voltage level.

[0061] Battery packs 44 and 46 can be connected to DC bus 66 via a fuse or other means configured to automatically disconnect in response to a collision, accident, or other event requiring rapid isolation of battery packs 44 and 46. For example, a switching system includes pyrotechnic switches 90 and 92 configured to be activated in response to such an event.

[0062] The first switching device 60 includes various switches for selectively connecting the battery pack 44 to components including an inverter and / or an electrical load. A first pair of switches 84 (SA1) and 86 (SA2) are provided for selectively connecting the battery pack 44 to a DC bus 66. Switch 84 (SA1) selectively connects the battery pack 44 to the positive side of the DC bus 66, and switch 86 (SA2) selectively connects the battery pack 44 to the negative side of the DC bus 66. The switching device 60 may also include a switch 88 (SA3) for selectively connecting the battery pack 44 to a charging port 54 (e.g., for DCFC charging).

[0063] The second switching device 62 includes various switches for selectively connecting the battery pack 46 to components including an inverter and / or an electrical load. A second pair of switches 94 (SB1) and 96 (SB2) are provided for selectively connecting the battery pack 46 to the DC bus 66. Switch 94 (SB1) selectively connects the battery pack 46 to the positive side of the DC bus 66, and switch 96 (SB2) selectively connects the battery pack 46 to the negative side of the DC bus 66. The switching device 62 may also include a switch 98 (SB3) for selectively connecting the battery pack 46 to the charging port 54.

[0064] As described above, when switching between operating modes corresponding to different applied voltages, the switching system is controlled to connect battery packs 44 and 46 in series or parallel. During this switching process, capacitors in the inverter and electrical load draw or drive current, resulting in potentially harmful current spikes (inrush currents). To prevent such inrush currents, the switching system is configured to perform a method of changing the voltage level by switching between parallel and series connections, which includes deactivating the connected electrical components and performing a pre-charge or discharge process that allows the capacitors to be charged or discharged during the switching.

[0065] In one embodiment, to facilitate pre-charging, the switching system includes a pre-charging circuit comprising a first pre-charging switch 100 (PCA) between the battery pack 44 and the propulsion bus 66 (positive side), a second pre-charging switch 102 (PCB) between the battery pack 46 and the propulsion bus 66, and a resistor for current limiting. The pre-charging circuit is operable to pre-charge the components in pairs when switching from a low-voltage operating mode (where the battery packs are connected in parallel) to a high-voltage operating mode (where the battery packs are connected in series). When switching from a high-voltage operating mode to a low-voltage operating mode, the pre-charging circuit is also operable to facilitate discharge of the components.

[0066] The switching system can operate in various configurations or switching states to control which battery pack supplies power to which inverter and to change the voltage applied to the inverter and other electrical components. In one embodiment, battery packs 44 and 46 both have the same nominal voltage (e.g., 400V), and switching devices 60, 62, and 64 can be controlled to connect battery packs 44 and 46 in parallel to provide a low voltage (the low voltage is the same as the battery pack voltage, and the total current is the sum of the currents through battery packs 44 and 46), and can be controlled to connect the battery packs in series to provide a high voltage (the high voltage is the sum of the individual voltages of battery packs 44 and 46).

[0067] In low-voltage operation mode, switches 80 (SE1) and 82 (SE2) are OFF, switches 84 (SA1) and 86 (SA2) are ON, and switches 94 (SB1) and 96 (SB2) are OFF. In this switching state, battery packs 44 and 46 are connected in parallel to bus 66. Battery pack 44 supplies power to the inverter using its battery voltage (low voltage, e.g., 400V), while battery pack 46 supplies power to the inverter separately at a low voltage.

[0068] In high-voltage operating mode, switches 80 (SE1) and 82 (SE2) are closed to connect battery pack 44 and battery pack 46 in series. Switch 84 (SA1) is closed, and switch 86 (SA2) is open. Switch 94 (SB1) is open, and switch 96 (SB2) is closed. In this switching state, battery packs 44 and 46 are connected in series to bus 66, and both battery packs 44 and 46 supply power to the inverter and electrical load at a high voltage (the high voltage is the sum of the battery voltages, e.g., 800V). Resistor 72 is provided to limit the current through the electrical load.

[0069] Figure 3-8 A method for controlling a vehicle's propulsion system (e.g., propulsion system 16) and switching between control operating modes (or activating operating modes) is described. This method provides activation of operating modes when the vehicle is stationary (vehicle propulsion system off), and switching between operating modes when the propulsion system is on. Aspects of this method can be executed by one or more processors disposed in the vehicle, such as controller 65. However, these methods are not limited thereto, as they can be executed by any suitable processing device or system, or a combination of processing devices.

[0070] For the purpose of explanation, combined with Figure 1 Vehicle 10 and Figure 2 These methods are discussed in the context of switching systems. However, these methods are not limited to this and can be implemented in any suitable vehicle or vehicle system utilizing multiple battery systems.

[0071] Figure 3 An embodiment of method 110 is shown, which controls the propulsion system of a vehicle and controls the switching between operating modes or the activation of an operating mode when the vehicle is stationary (propulsion system off). Method 110 includes multiple steps or stages represented by blocks 111-116. Method 110 is not limited to the number or order of the steps. For example, the steps represented by blocks 111-116 may be performed sequentially or in a different order than that described below.

[0072] Method 110 begins when controller 65 receives a request to place vehicle 10 into an operating mode corresponding to a selected voltage level. The request may be provided by a user or an external system, or by the vehicle system itself.

[0073] For example, at box 111, user input is received from the driver or other user (e.g., through interaction with computer system 55). This input may include selecting an operating mode or providing information about road conditions or other environmental conditions. At box 112, controller 65 may receive route information, monitoring data (e.g., external camera and / or radar data, user monitoring data related to driver status, etc.) and / or other information for automatically selecting an operating mode.

[0074] In block 113, controller 65 selects an operating mode and an associated voltage level. In one embodiment, controller 65 detects a user request for a specific operating mode and selects the operating mode based on user input regarding environmental conditions (e.g., selecting a low-voltage operating mode in an urban environment) or based on route information.

[0075] In box 114, propulsion system 16 is activated or started. For example, controller 65 activates propulsion system 16 or sends a request to vehicle controller, motor controller, or other device or system to activate propulsion system 16.

[0076] In block 115, controller 65 determines whether battery packs 44 and 46 are disconnected from inverters 24, 34L, and 34R, as well as the electrical loads (i.e., whether switching devices 60, 62, and 64 are all disconnected). For example, controller 65 detects the switching position or state of each switch of switching devices 60, 62, and 64. If any switch is closed, controller 65 disconnects any closed switch. Controller 65 performs any additional functions to ensure that battery packs 44 and 46 are disconnected from the inverters and electrical loads. Once battery packs 44 and 46 are determined to be disconnected, method 110 proceeds to block 116.

[0077] In box 116, controller 65 initiates the selected operating mode. For example, controller 65 closes switches 84 (SA1), 86 (SA2), 94 (SB1), and 96 (SB2) to connect the battery packs in parallel to DC bus 66 (or simply closes the switches required to connect a single battery pack to DC bus 66), so that energy from battery pack 44 and / or battery pack 46 is supplied at a low voltage (e.g., 400V). In another example, if the selected operating mode is a high-voltage operating mode, controller 65 closes switches 80 (SE1), 82 (SE2), 84 (SA1), and 96 (SB2) to supply energy at a high voltage (e.g., 800V).

[0078] Then, by controlling the switches in inverters 24, 34L and / or 34R to drive motors 22, 32L and / or 32R, vehicle 10 can operate in the selected operating mode.

[0079] Figure 4 An embodiment of method 120 is shown, which controls the propulsion system of a vehicle and controls the switching between operating modes or initiation of an operating mode when the vehicle's propulsion system is activated (e.g., during driving). Method 120 includes a plurality of steps or stages represented by boxes 121-128. Method 120 is not limited to the number or order of the steps. For example, the steps represented by boxes 121-128 may be performed sequentially or in an order different from that described below.

[0080] In block 121, controller 65 receives a request to switch vehicle 10 from an initial operating mode to a desired or target operating mode. For example, controller 65 may receive a request to switch from a normal mode driving motors 22, 32L, and / or 32R at a relatively low voltage (e.g., 400V or 600V) to a high-performance mode driving motors 22, 32L, and / or 32R at a relatively high voltage (e.g., 800V) or other modes. This request may be provided by a user or external system, or by the vehicle system itself. For example, the request may be input from the driver, from another vehicle system (e.g., a driver monitoring system, a navigation system, etc.), or from an external device or system. Controller 65 selects the operating mode and associated voltage level based on the request.

[0081] In block 122, controller 65 detects whether vehicle 10 is under conditions in which the operating mode and applied voltage can be changed without causing harmful effects. For example, controller 65 determines whether the condition that no torque is applied to vehicle 10 is met. One such condition is that the vehicle brakes are engaged and vehicle 10 is not moving. Another condition is that each motor 22, 32L, and 32R is stationary (or below a selected motor speed). If the condition is not met, method 120 proceeds to block 123. If the condition is met, method 120 proceeds to block 125.

[0082] In box 123, controller 65 instructs vehicle 10 to apply braking (e.g., autonomous braking) or instructs the driver to apply braking. Optionally, in box 124, controller 65 may query the appropriate vehicle system to ensure no torque request is issued, and / or provide the driver with output indicating that a transition is in progress (e.g., a notification on user interface 58 or an auditory notification).

[0083] In box 125, vehicle 10 transitions from an initial operating mode to a desired operating mode. During the transition, electrical loads (e.g., ACEC68 and IPEO70) are deactivated or switched off (e.g., placed in standby mode), and the applied voltage is increased or decreased from the initial voltage by controlling the switching system as described herein. Also during the transition, inverters 24, 34L, and 34R, as well as the electrical loads, are pre-charged or discharged to reduce or prevent inrush current.

[0084] In box 126, after the transition is complete, the electrical load is reactivated or turned on. In box 127, the brake is released (or the user is prompted to release the brake). The driver may be notified of the transition completion (box 128) via user interface 58 or other means.

[0085] Figure 5An embodiment of method 130 for switching from the initial operating mode is described when the target operating mode uses a desired or target voltage level greater than the initial voltage level (i.e., the voltage level applied when vehicle 10 is in the initial operating mode). In the initial operating mode, battery pack 44 is connected in parallel with battery pack 46. Switches 80 (SE1) and 82 (SE2) are open, switch 84 (SA1) is closed, and switch 86 (SA2) is closed. Switch 94 (SB1) is closed, and switch 96 (SB2) is closed.

[0086] Method 130 may be performed at block 125 of method 120. Method 130 includes multiple steps or stages represented by blocks 131-140, but is not limited to the number or order of the steps.

[0087] In block 131, controller 65 measures the current through the series connection between battery packs 44 and 46, and also measures the current through DC bus 66. If the measured current is zero or close to zero, method 130 proceeds to block 132. Otherwise, method 130 ends.

[0088] In block 132, controller 65 disables the electrical loads and inverters 24, 34L, and 34R. For example, controller 65 sends a signal or otherwise causes inverters 24, 34L, and 34R, as well as connected electrical loads (e.g., ACEC68 and IPEO70), to be placed in standby mode.

[0089] In box 133, the voltages of battery packs 44 and 46 are measured and recorded as the initial voltages of the measurement (HV). ini ).

[0090] In box 134, switch 84 (SA1) is open, switch 86 (SA2) is open, and switch 94 (SB1) is open. Switch 96 (SB2) remains closed.

[0091] In box 135, measure the current voltage and compare it with the measured initial voltage HV. ini A comparison is made to ensure that switches 84 (SA1), 86 (SA2), and 94 (SB1) successfully disconnect and that no conditions exist that could short-circuit the battery pack. For example, HV ini The difference between the target voltage and the threshold voltage is compared to a threshold difference (e.g., approximately 10V). If the difference is high enough, controller 65 confirms that switches 84 (SA1), 86 (SA2), and 94 (SB1) are all open.

[0092] In box 136, if the difference is greater than the threshold difference, battery packs 44 and 46 are connected in series. For example, switches 80 (SE1) and 82 (SE2) are closed.

[0093] In block 137, controller 65 confirms the series switch is closed. If confirmation is successful, in block 138, precharge switch 100 (PCA) closes, and battery pack 44 is used to precharge inverters 24, 34L, and 34R, as well as the electrical loads (i.e., to charge the capacitors therein). During precharging, current and / or voltage are monitored (e.g., via voltage sensors at each inverter and each electrical load).

[0094] In block 139, controller 65 monitors the current voltage at the inverter and load and compares the current voltage to a target voltage. In one embodiment, the target voltage is the average voltage of the battery pack. When the current voltage reaches the target voltage (e.g., is the same as the target voltage, or is within a selected range of the target voltage), method 130 proceeds to block 140.

[0095] In box 140, switch 84 (SA1) is closed to complete the series circuit and allow operation at the target voltage.

[0096] Figure 6-8 Embodiments of methods for switching from an initial operating mode when the target operating mode uses a desired or target voltage level lower than the initial voltage level are described. In each of these methods (methods 150, 170, and 190), the initial operating mode is a high-voltage operating mode, and the controller 65 switches to a low-voltage operating mode. In the initial operating mode, switch 84 (SA1) is closed, switch 86 (SA2) is open, switch 94 (SB1) is open, and switch 96 (SB2) is closed. Switches 80 (SE1) and 82 (SE2) are closed, thereby connecting battery pack 44 in series with battery pack 46.

[0097] Figure 6 An embodiment of method 150 for transitioning from an initial operating mode to a target operating mode is illustrated. Method 150 may be performed at block 125 of method 120. Method 150 includes multiple steps or stages represented by blocks 151-163, but is not limited to the number or order of the steps.

[0098] In block 151, controller 65 measures the current through the series connection between battery packs 44 and 46, and also measures the current through DC bus 66. If the measured current is zero or close to zero, method 150 proceeds to block 152. Otherwise, method 150 ends.

[0099] In box 152, controller 65 deactivates (e.g., puts into standby) the electrical load and inverters 24, 34L, and 34R. In box 153, the voltage of the series-connected battery packs (the sum of the voltages of the individual battery packs) is measured and recorded as the initial voltage of the measurement (HV). ini ).

[0100] In box 154, series switches 80 (SE1) and 82 (SE2) are open. Additionally, switch 84 (SA1) is open. Switch 96 (SB2) remains closed.

[0101] In box 155, the current voltage is measured (e.g., via voltage sensors at the inverter and load) and compared with the measured initial voltage HV. ini Compare these parameters to confirm that switches 80 (SE1), 82 (SE2), and 84 (SA1) are open. For example, if HV ini If the difference between the voltage and the target voltage is greater than a selected threshold (e.g., about 10V), the switch is considered open.

[0102] In box 156, if the difference is greater than the threshold difference, a discharge timer is set, which corresponds to the amount of time required (or expected to be required) for the capacitors and electrical loads in inverters 24, 34L and 34R to discharge, so that the voltage of these components drops to the target voltage level.

[0103] In box 157, at the end of the timer, controller 65 closes switch 86 (SA2), and in box 158, the current voltage is measured again. If the current voltage is within a selected range of the target voltage (e.g., approximately 50V), method 150 continues. For example, the target voltage is defined as the average voltage of battery packs 44 and 46 and compared with the current voltage. If the current voltage is outside this range, switch 86 (SA2) is reopened, and controller 65 waits for an additional period of time to allow for further discharge.

[0104] In box 159, if the current voltage is within the selected range, controller 65 closes switch 94 (SB1). In box 160, controller 65 confirms that switch 86 (SA2) is closed, and then closes switch 84 (SA1) in box 161.

[0105] In block 162, controller 65 confirms that switches 84 (SA1) and 94 (SB1) are closed. In block 163, battery packs 44 and 46 are confirmed to be connected in parallel to inverters 24, 34L and 34R and the load, and vehicle 10 can operate at the target voltage in the target operating mode.

[0106] Figure 7 An embodiment of method 170 for transitioning from an initial operating mode to a target operating mode is shown, which can be performed at block 125 of method 120. Method 170 includes multiple steps or stages represented by blocks 171-183, but is not limited to the number or order of the steps.

[0107] In block 171, controller 65 measures the current through the series connection between battery packs 44 and 46, and also measures the current through DC bus 66. If the measured current is zero or close to zero, method 170 proceeds to block 172. Otherwise, method 170 ends. Note that at this stage, precharge switches 100 (PCA) and 102 (PCB) are off.

[0108] In block 172, controller 65 puts the electrical load and inverters 24, 34L, and 34R into standby mode, and in block 173, measures the voltage of the series-connected battery packs 44 and 46 and records it as the initial voltage of the measurement (HV). ini In box 174, series switches 80 (SE1) and 82 (SE2) are open, and switch 84 (SA1) is open. Switch 96 (SB2) remains closed.

[0109] In box 175, the current voltage is measured (e.g., via voltage sensors at the inverter and load) and compared with the measured initial voltage HV. ini Compare these parameters to confirm that switches 80 (SE1), 82 (SE2), and 84 (SA1) are open. For example, if HV ini If the difference between the voltage and the target voltage is greater than the selected threshold difference, then the switch is confirmed to be open.

[0110] In box 176, if the difference is greater than the threshold difference, the precharge switch 102 (PCB) closes, and in box 177, switch 86 (SA2) also closes. Inverters 24, 34L, and 34R, as well as the electrical load, actively discharge via the precharge switch 102 (PCB) and the resistor.

[0111] In box 178, during discharge, controller 65 monitors the current voltage and compares it with a target voltage (e.g., the average value of the battery pack voltage). Monitoring and comparison can be performed periodically or continuously and repeated until the current voltage is within a selected range of the target voltage (e.g., approximately 50V).

[0112] In box 179, if the current voltage is within the selected range, controller 65 closes switch 94 (SB1) and then opens precharge switch 102 (PCB). In box 180, controller 65 confirms that switch 86 (SA2) is closed, and then closes switch 84 (SA1) in box 181.

[0113] In block 182, controller 65 confirms that switches 84 (SA1) and 94 (SB1) are closed. In block 183, battery packs 44 and 46 are confirmed to be connected in parallel to the inverter and the load, and vehicle 10 can operate at the target voltage in the target operating mode.

[0114] Figure 8An embodiment of method 190 for transitioning from an initial operating mode to a target operating mode is shown, which can be performed at block 125 of method 120. Method 190 includes multiple steps or stages represented by blocks 191-203, but is not limited to the number or order of the steps.

[0115] In block 191, controller 65 measures the current through the series connection between battery packs 44 and 46, and also measures the current through DC bus 66. If the measured current is zero or close to zero, method 190 proceeds to block 192; otherwise, method 190 ends.

[0116] In block 192, controller 65 puts the electrical load and inverters 24, 34L, and 34R into standby mode, and in block 193, measures the voltage of the series-connected battery packs 44 and 46 and records it as the initial voltage of the measurement (HV). ini In box 194, series switches 80 (SE1) and 82 (SE2) are open, and switch 84 (SA1) is open. Switch 96 (SB2) remains closed.

[0117] In box 195, the current voltage is measured (e.g., via voltage sensors at the inverter and load) and compared with the measured initial voltage HV. ini Compare these parameters to confirm that switches 80 (SE1), 82 (SE2), and 84 (SA1) are open. For example, if HV ini If the difference between the voltage and the target voltage is greater than the selected threshold difference, then the switch is confirmed to be open.

[0118] In box 196, if the difference is greater than a threshold difference, one of the electrical loads is selected as the active component and reactivated. For example, an electrical component such as ACEC68 or a cabin heater is activated. In box 197, switch 86 (SA2) is also closed. Inverters 24, 34L, and 34R, as well as the electrical loads, are actively discharged using the active component of the active discharge mechanism.

[0119] For example, inverters 24, 34L, and 34R, along with the electrical load, are actively discharged by controlling a switch in one of the inverters to generate AC current (also known as direct-axis or d-axis current) in the corresponding motor without producing torque. In another example, one or more components (such as one or more of inverters 24, 34L, and 34R, and the electrical load) are actively discharged using a resistor across the capacitor by closing a switch between a resistor and a capacitor.

[0120] In box 198, during discharge, controller 65 monitors the current voltage and compares it with a target voltage. Monitoring and comparison can be repeated until the current voltage falls within a selected range of the target voltage (e.g., approximately 50V).

[0121] In box 199, if the current voltage is within the selected range, controller 65 closes switch 94 (SB1). In box 200, controller 65 confirms that switch 86 (SA2) is closed, and then closes switch 84 (SA1) in box 201.

[0122] In block 202, controller 65 confirms that switches 84 (SA1) and 94 (SB1) are closed. In block 203, battery packs 44 and 46 are confirmed to be connected in parallel, and vehicle 10 can operate at the target voltage in the target operating mode.

[0123] Figure 9 Aspects of an embodiment of computer system 240 are illustrated, which can perform various aspects of the embodiments described herein. Computer system 240 includes at least one processing unit 242, which typically includes one or more processors, for performing aspects of the image acquisition and analysis methods described herein.

[0124] The components of computer system 240 include processing device 242 (such as one or more processors or processing units), memory 244, and bus 246 coupling various system components, including system memory 244, to processing device 242. System memory 244 may be a non-transitory computer-readable medium and may include various computer system-readable media. Such media may be any available medium accessible by processing device 242, including volatile and non-volatile media, as well as removable and non-removable media.

[0125] For example, system memory 244 includes non-volatile memory 248 such as a hard disk drive, and may also include volatile memory 250 such as random access memory (RAM) and / or cache memory. Computer system 240 may also include other removable / non-removable, volatile / non-volatile computer system storage media.

[0126] System memory 244 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. For example, system memory 244 stores various program modules that typically perform the functions and / or methods of the embodiments described herein. One or more modules 252 may be included to perform functions related to performing measurements, and one or more modules 254 may be included to perform functions related to controlling switching devices, as discussed herein. System 240 is not limited thereto, as it may include other modules. As used herein, the term "module" refers to processing circuitry, which may include application-specific integrated circuits (ASICs), electronic circuitry, processors (shared, dedicated, or grouped) and memories executing one or more software or firmware programs, combinational logic circuitry, and / or other suitable components providing the said functions.

[0127] The processing device 242 can also communicate with one or more external devices 256, which can be a keyboard, a pointing device, and / or any device that enables the processing device 242 to communicate with one or more other computing devices (e.g., a network card, a modem, etc.). Communication with various devices can be made through input / output (I / O) interfaces 264 and 265.

[0128] Processing device 242 can also communicate with one or more networks 266 via network adapter 268, such as a local area network (LAN), a general wide area network (WAN), a bus network, and / or a public network (e.g., the Internet). It should be understood that, although not shown, other hardware and / or software components may be used in conjunction with computer system 240. Examples include, but are not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, and data archiving storage systems.

[0129] The terms “a” and “an” do not indicate a limitation of quantity, but rather that at least one of the referenced items is present. The term “or” means “and / or”, unless the context clearly indicates otherwise. A reference to “an aspect” throughout the specification means that a particular element (e.g., feature, structure, step, or characteristic) described in connection with that aspect is included in at least one aspect described herein and may or may not be present in other aspects. Furthermore, it should be understood that the described elements may be combined in any suitable manner across the aspects.

[0130] When an element, such as a layer, film, region, or substrate, is referred to as being "on" another element, it can be directly on the other element, or there may be intermediate elements present. Conversely, when an element is referred to as being "directly on" another element, there are no intermediate elements present.

[0131] Unless otherwise stated herein, all test standards are the most recent valid standards up to the filing date of this application, or, if priority is claimed, the filing date of the earliest priority application in which the test standard appears.

[0132] Unless otherwise defined, the 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 pertains.

[0133] While the foregoing disclosure has been described with reference to exemplary embodiments, those skilled in the art will understand that various changes can be made and equivalents can replace its elements without departing from its scope. Furthermore, many modifications can be made to adapt particular situations or materials to the teachings of this disclosure without departing from its essential scope. Therefore, it is intended that this disclosure be limited to the specific embodiments disclosed, but will include all embodiments falling within its scope.

Claims

1. A system for controlling propulsion in a vehicle, comprising: A switching system connected to a battery system, the battery system including a first battery assembly and a second battery assembly selectively connected to a drive unit and one or more electrical loads via a propulsion bus, the switching system including a first switching device configured to selectively connect the first battery assembly to the propulsion bus, a second switching device configured to selectively connect the second battery assembly to the propulsion bus, and a third switching device configured to selectively connect the first battery assembly to the second battery assembly; as well as A controller configured to control a switching system to change the voltage applied to the drive unit during vehicle propulsion, the controller being configured to receive a request to switch from a first operating mode to a second operating mode, the switching comprising changing the voltage applied to the drive unit from an initial voltage level to a target voltage level, and performing the switching sequentially: Disconnect one or more electrical loads; Pre-charge one or more electrical loads based on the target voltage being higher than the initial voltage; Based on the target voltage being lower than the initial voltage, a discharge process is performed to discharge the capacitors in each of one or more electrical loads; as well as The operating switch system applies voltage to the drive unit at the target voltage level.

2. The system according to claim 1, wherein, The switching system operates to connect the first battery assembly in series to the second battery assembly based on the target voltage level being higher than the initial voltage level, and the switching system operates to connect the first battery assembly in parallel to the second battery assembly based on the target voltage level being lower than the initial voltage level.

3. The system according to claim 2, wherein, The first switching device includes a first pair of switches for selectively connecting the first battery assembly to the propulsion bus, and the second switching device includes a second pair of switches for selectively connecting the second battery assembly to the propulsion bus.

4. The system according to claim 3, wherein, The switching system includes a pre-charge circuit having a first pre-charge switch connected to the first battery assembly and a second pre-charge switch connected to the second battery assembly. The target voltage is higher than the initial voltage. In the first operating mode, the first pair of switches is closed, the second pair of switches is closed, the third switching device is open, the first and second pre-charge switches are open, and the first battery assembly is connected in parallel to the second battery assembly. The pre-charging includes: Disconnect the first pair of switches, and disconnect one of the switches in the second pair; Close the third switch to connect the first battery assembly in series with the second battery assembly; Close the first precharge switch and precharge the one or more electrical loads to the target voltage level; and After one or more electrical loads are at the target voltage level, the first pre-charge switch is disconnected and one of the second pair of switches is closed.

5. The system according to claim 3, wherein, The target voltage is lower than the initial voltage, and in the first operating mode, one of the first pair of switches is open and the other of the first pair of switches is closed, one of the second pair of switches is open and the other of the second pair of switches is closed, the third switching device is closed, and the first battery assembly is connected in series to the second battery assembly through the third switching device.

6. The system according to claim 5, wherein, The discharge includes: Disconnect the one or more electrical loads; Disconnect the third switching device; Disconnect the other of the first pair of switches; Close one of the first pair of switches; Discharge one or more electrical loads to the target voltage level; Monitor the voltage during discharge and compare the difference between the monitored voltage and the target voltage; and Based on the difference being less than a threshold difference, one of the second pair of switches is closed, and the other of the first pair of switches is closed, to connect the first battery assembly in parallel to the second battery assembly.

7. The system according to claim 5, wherein, The one or more electrical loads include a plurality of electrical loads, and the discharge includes: Disconnect multiple electrical loads; Disconnect the third switching device; Disconnect the other of the first pair of switches; Activate one of the multiple electrical loads and close one of the first pair of switches; Multiple electrical loads are discharged to the target voltage level by activating the load; Monitor the voltage during discharge and compare the difference between the monitored voltage and the target voltage; and Based on the difference being less than a threshold difference, one of the second pair of switches is closed and the other of the first pair of switches is closed to connect the first battery assembly in parallel to the second battery assembly and reactivate the multiple electrical loads.

8. The system according to claim 5, wherein, The switching system includes a pre-charge circuit having a first pre-charge switch connected to the first battery assembly and a second pre-charge switch connected to the battery assembly, and the discharging includes: Disconnect the third switching device; Disconnect the other of the first pair of switches; Close the second pre-charge switch and close one of the first pair of switches; The one or more electrical loads are discharged to the target voltage level by a resistor connected to the second pre-charge switch; Monitor the voltage during discharge and compare the difference between the monitored voltage and the target voltage; and Based on the difference being less than a threshold difference, one of the second pair of switches is closed, the second pre-charge switch is opened, and the other of the first pair of switches is closed to connect the first battery assembly in parallel to the second battery assembly.

9. A method for controlling vehicle propulsion, comprising: The system receives a request to switch from a first operating mode to a second operating mode, the switching including changing the voltage applied to the drive unit of the vehicle from an initial voltage level to a target voltage level. The vehicle includes a switching system connected to a battery system, the battery system including a first battery assembly and a second battery assembly selectively connected to the drive unit and one or more electrical loads via a propulsion bus. The switching system includes a first switching device configured to selectively connect the first battery assembly to the propulsion bus, a second switching device configured to selectively connect the second battery assembly to the propulsion bus, and a third switching device configured to selectively connect the first battery assembly to the second battery assembly. Disconnect one or more electrical loads; Pre-charge one or more electrical loads based on the target voltage being higher than the initial voltage; Based on the target voltage being lower than the initial voltage, a discharge process is performed to discharge the capacitors in each of one or more electrical loads; as well as The operating switch system applies voltage to the drive unit at the target voltage level.

10. The method according to claim 9, wherein, Operating the switching system includes one of the following: Based on the fact that the target voltage level is higher than the initial voltage level, the first battery assembly is connected in series to the second battery assembly, and Based on the fact that the target voltage level is lower than the initial voltage level, the first battery module is connected in parallel to the second battery module.

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