Electrical system with boost converter function

Abstract

Electrical system comprising: a rechargeable energy storage system (RESS) (115); an inverter (162) connected to the RESS (115), the inverter (162) configured to supply electrical energy to a traction motor (114); a plurality of machine windings (166) connected between a plurality of first switches (156) and the traction motor (114), each switch (Sa-Sc) of the plurality of first switches (156) being configured to transition between a closed state to allow current flow between the inverter (162) and the traction motor (114) and an open state to prevent current flow between the inverter (162) and the traction motor (114); and a plurality of inductor windings (167) connected between a plurality of second switches (158) and an off-board power source (30), each switch (Sx-Sz) of the plurality of second switches (158) being configured to transition between a closed state to allow current flow between the off-board power source (30) and the inverter (162) for charging the RESS (115) and an open state to prevent current flow between the off-board power source (30) and the inverter (162).

Description

[0001] This description refers to an electrical vehicle system with boost converter function.

[0002] A hybrid or battery-electric vehicle transmission typically comprises one or more multi-phase, high-voltage electric machines in the form of a motor-generator unit or an electric traction motor. The electric machines supply or draw energy from a rechargeable direct current (DC) battery. The excited electric machines adjust the torques of the transmission's various gear sets to achieve optimal system efficiency. A DC boost converter is typically used to increase the battery's output voltage to a level suitable for the electric machines.

[0003] The semiconductor switches of an inverter module are controlled via pulse-width modulation or other switching control signals to convert the boosted battery output voltage into an AC output voltage. The AC output voltage of the inverter module is ultimately transferred to the individual phase windings of the electric machine. The excited electric machine drives the vehicle's powertrain.

[0004] US 2021 / 0 001 738 A1 describes an all-wheel drive vehicle comprising main drive wheels and auxiliary drive wheels; a first drive motor that supplies power to the main drive wheels; a second drive motor that supplies power to the auxiliary drive wheels; a battery that stores electrical energy; an inverter that converts the electrical energy stored in the battery and makes it available to the first drive motor; and a bidirectional power converter that generates electrical charging current for charging the battery by converting current supplied from outside the vehicle and converts the electrical energy stored in the battery and makes it available to the second drive motor.

[0005] US 2016 / 0 152 153 A1 describes a charging system for an electric vehicle and a method for controlling the charging of an electric vehicle. The charging system comprises: a power battery; a charge / discharge socket; an external power supply; a charging connection device; and a power control device comprising: a three-stage bidirectional DC-AC module; a charge / discharge control module; and a control module that controls the charge / discharge control module according to the current operating mode of the electric vehicle. The power control device and the external power supply communicate with each other via the charging connection device by transmitting a modulated PWM signal. The control module controls the three-stage bidirectional DC-AC module and the charge / discharge control module to charge the power battery via the external power supply.

[0006] US 10 917 030 B1 describes an electric drive system comprising a battery pack, an inverter module (PIM), an electric machine, a switching circuit, and a controller. The electric machine has three or more phase branches. The PIM is connected to the battery pack with a direct current side and to the electric machine with an alternating current (AC) side. The switching circuit includes AC switches. For each phase branch, the circuit also includes three or more winding sections, each of which can be electrically connected to or disconnected from the PIM via the AC switches. The controller controls a binary switching state of each AC switch depending on the speed in order to implement one of four different speed-dependent operating modes of the electric machine and thereby vary the conduction path from the PIM to the electric machine via one or more of the connected winding sections.

[0007] RU 175 680 U1 describes a system for charging a traction power source and supplying electrical power to traction electric motors of electric and hybrid vehicles. The traction voltage converter with integrated charging device contains a charging converter, an inverter, a switching device, and a control unit as its main components. The charging converter consists of inductive and capacitive electrical energy storage devices, a semiconductor switch, and diodes. The key collector is connected to the inverter's positive DC bus. Switching the semiconductor switch ensures the specified charging operation of the traction energy storage device. The output circuit of the charging converter is connected to the inverter's power rails. The inverter controls the electric motor and rectifies the AC voltage when charging the energy storage device.The inverter's power phase terminals are connected to the switching device. This device ensures the separation of the electric machine from the inverter and the connection of an external electrical energy source for charging the traction storage system. The operation of the traction converter is controlled by the control unit.

[0008] It can be considered a task to specify an improved electrical system.

[0009] The object is achieved by an electrical system according to claim 1. Furthermore, a method is described with which the system according to the invention can be operated.

[0010] An electrical system is described. The electrical system according to the invention may include a rechargeable energy storage system (RESS) and an inverter connected to the RESS. The inverter may be configured to supply electrical power to a traction motor. The electrical system includes a plurality of machine windings connected between a plurality of first switches and the traction motor. Each switch of the plurality of first switches is configured to transition between a closed state allowing current flow between the inverter and the traction motor and an open state preventing current flow between the inverter and the traction motor. The electrical system includes a plurality of inductor windings connected between a plurality of second switches and an off-board power source.Each of the plurality of second switches is configured to alternate between a closed state that allows current to flow between the off-board power source and the inverter for charging the RESS and an open state that prevents current to flow between the off-board power source and the inverter.

[0011] In one embodiment, each winding of the plurality of machine windings consists of windings of the traction motor.

[0012] In one embodiment, each winding of the plurality of inductor windings is arranged around a common magnetic core.

[0013] In one embodiment, each winding of the plurality of inductor windings is arranged around a different magnetic core.

[0014] In one embodiment, the inverter comprises a series of semiconductor switches configured to convert direct current (DC) to alternating current (AC).

[0015] In one embodiment, each semiconductor switch of the semiconductor switch set consists of a voltage controlled switching device.

[0016] In one embodiment, the voltage controlled switching device comprises at least one of a silicon insulated gate bipolar transistor (IGBT), a silicon carbide metal oxide semiconductor field effect transistor (MOSFET), a silicon superjunction MOSFET, a gallium nitride field effect transistor (FET), a SiC junction field effect transistor (JFET), a wide band gap (WBG) device, or an ultra wide band gap (UWBG) device.

[0017] In one embodiment, the inverter comprises a plurality of phase legs, each phase leg of the plurality of phase legs comprising a pair of semiconductor switches from the set of semiconductor switches, each phase leg being selectively connected to a corresponding one of the plurality of machine windings or a corresponding one of the plurality of inductors.

[0018] In one embodiment, at least one semiconductor switch of a first phase leg and a second phase leg is pulse width modulated to enable a current flow through at least one of the two phase legs.

[0019] In one embodiment, current flows through at least two inductor windings of the plurality of inductor windings to increase a voltage from the off-board power source from a first voltage to a second voltage.

[0020] In one embodiment, the electrical system includes a controller connected to the plurality of first switches, the plurality of second switches, and an inverter controller. The controller is configured to transmit control signals to the plurality of first switches, the plurality of second switches, and the inverter controller to enable current flow between the off-board power source and the inverter to charge the RESS during a charging operation.

[0021] In one embodiment, the control unit receives software updates via over-the-air programming.

[0022] In one embodiment, the controller is configured to transmit control signals to control current flow to mitigate torque disturbances and increase the functionality of the converter.

[0023] An exemplary method is described that may include determining whether a connection to an off-board power source has been established. The method may also include transmitting at least one control signal to an inverter and to at least one first switch to prevent current flow between the inverter and a plurality of machine windings of a traction motor, and to at least one second switch to allow current flow between the off-board power source through a plurality of inductor windings to a rechargeable energy storage system (RESS) during a charging operation.

[0024] The majority of the inductor windings can be arranged in the RESS or in the inverter. Fig. 1A is a schematic diagram of an example motor vehicle connected to an off-board DC fast charging station; Fig. 1B is a schematic representation of an example of a motor vehicle connected to another motor vehicle for vehicle-to-vehicle charging; Fig. 2A is a block diagram of an example electrical system according to an example implementation; Fig. 2B is a block diagram of an example electrical system according to an example implementation; Fig. 3 is a circuit diagram of the electrical system according to one embodiment; Fig. 4 is a flowchart illustrating an example process for charging a RESS of a vehicle from an off-board power source according to an example implementation.

[0025] Some hybrid or battery electric vehicles may have integrated rechargeable energy storage systems (RESS) that store a voltage greater than the voltage available to charge the vehicle's RESS. In these cases, the vehicle may require an additional DC-DC converter to boost the voltage from an off-board power source to the RESS during charging. Additional DC-DC converters can increase the cost, mass, and volume of the vehicle.

[0026] This specification describes an electrical system that provides boost converter functionality via inverter switches and a set of inductor windings. For example, a controller, such as an inverter controller, can selectively transition one or more switches from an open state to a closed state, or vice versa, to cause electrical power to be directed from an off-board power source to the RESS. The electrical power can be directed through one or more of the inductor windings via an inverter, increasing the voltage relative to the voltage of the off-board power source.

[0027] Fig. 1A shows an example of a DC charging circuit 10 as part of a motor vehicle 20. The vehicle 20 is illustrated as undergoing a DC fast charging process, with the DC charging circuit 10 electrically connected to an off-board DC fast charging station 30 via a charging port 11 and a charging cable 15, e.g., using an SAE J1772 charging plug, CHAdeMO, or other suitable regional or national standard charging plug or connector. The present teachings are independent of the particular charging standard ultimately used in a DC fast charging process with the DC fast charging station 30, and therefore, the above examples are merely illustrative.

[0028] The DC charging circuit 10 can be used as part of the motor vehicle 20 as well as other electrical systems such as stationary or mobile power plant robots or platforms. In vehicular applications, non-motor vehicles such as aircraft, watercraft, and rail vehicles can also benefit from similar advantages. The DC charging circuit 10 can be protected as part of a powertrain of a mobile system, such as the example vehicle 20. For illustrative purposes, an application of the DC charging circuit 10 as an integral part of the vehicle 20 in an automotive context is described below, without limiting the present description to such an implementation.

[0029] The vehicle 20 of Fig. 1A includes a body 12 and drive wheels 14. The body 12 may define or contain the charging port 11 at a location accessible to the user. The vehicle 20 may be variously configured as a plug-in electric vehicle with an onboard rechargeable energy storage system (RESS) 115, as shown in FIGS. Fig. 2A and Fig. 2B and described below, for example, a multi-cell lithium-ion, zinc-air, nickel-metal hydride, or lead-acid DC battery pack that can be selectively charged using the off-board DC fast charging station 30 of Fig. 1A. The DC charging circuit 10, as best described in the Fig. 2A and Fig. 2B, includes powertrain / driveline components of the vehicle 20, the common functions of which may include driving an electric machine (ME), such as a traction motor 114, to generate and deliver motor torque to the drive wheels 14 for propelling the vehicle 20 or performing other useful work on board the vehicle 20. Fig. 1B illustrates an example implementation of vehicle-to-vehicle (V2V) charging. As shown, a first vehicle 20-1 may be used to at least partially charge a second vehicle 20-2, or vice versa. The first vehicle 20-1 and / or the second vehicle 20-2 may include an electrical system as described herein.

[0030] The Fig. 2A and Fig. 2B show a block diagram of an electrical system 100 for the vehicle 20 according to various implementations. As shown, the electrical system 100 includes the on-board rechargeable energy storage system (RESS) 115, which is suitable for storing high-voltage electrical energy required to power an electric vehicle, such as the vehicle 20 of Fig. 1A. The RESS 115 may be a deep-cycle, high-amperage battery system rated for approximately four hundred (400) to approximately eight hundred (800) volts direct current (VDC) or more, depending, for example, on the desired vehicle range, the gross vehicle weight, and the power ratings of the various loads that draw electrical energy from the RESS 115 in various implementations. However, it is understood that the RESS 115 may also be rated for other voltages. A DC link capacitor Co may be connected between the positive and negative terminals of the inverter, as shown in Fig. 3 shown.

[0031] The RESS 115 may include one or more independently rechargeable high-voltage batteries. The RESS 115 may be connected to a high-voltage DC bus 160 and an inverter 162 to control the transfer of electrical energy to and from the traction motor 114.

[0032] The vehicle 20 may also include one or more accessory loads 170. In one example implementation, the accessory loads 170 may include various loads that draw electrical power from the electrical system 100. In one embodiment, the RESS 115 may be configured to store a first voltage, e.g., approximately eight hundred (800) VDC. However, an off-board power source, such as the off-board DC fast charging station 30 or another vehicle, may be configured to supply a voltage at a second voltage lower than the first voltage, e.g., four hundred (400) VDC. As explained in more detail below, the electrical system 100 may be configured to boost the voltage supplied by the off-board power source.

[0033] The electrical system 100 further includes a controller 150, a first switch 102, a second switch 103, and a third switch 104 for controlling a DC-DC boost operation for supplying electrical energy to the RESS 115 from the off-board power source. The illustrated off-board power source includes a DC rapid charging station 30, but it is understood that the off-board power source may also include another vehicle.

[0034] Switches 102, 103, and 104 may be contactors or solid-state relays that close under electrical load to provide instantaneous or near-instantaneous electrical power to the vehicle's propulsion system and operate any number of accessories within the vehicle. In another embodiment, one or more of switches 102 and 103 may be replaced with a single-pole, double-throw (SPDT) switch. In this implementation, SPDT 105 is controllable by controller 150 to allow the off-board power source to be connected either to RESS 115 or to a set of inductor windings 167, which will be discussed in more detail below.

[0035] The controller 150 may include at least a processor and sufficient memory for storing computer-readable instructions. The memory includes tangible, non-transitory memory, such as read-only memory, whether optical, magnetic, flash, or other memory. The controller 150 also includes sufficient amounts of random-access memory, electrically erasable programmable read-only memory, and the like, as well as a high-speed clock, analog-to-digital and digital-to-analog circuitry, input / output circuitry and devices, and suitable signal conditioning and buffering circuitry. The controller 150 may receive charge request signals from one or more electronic control units (ECUs) of the vehicle 20.For example, a controller connected to the vehicle charging station or vehicle-to-vehicle communication system may provide a signal indicating that the RESS 115 needs to be charged from a source with a lower voltage than the RESS voltage, and the controller 150 may initiate boost DC-DC operation, as described below. If the DC fast charging station 30 is capable of directly supplying the required charging voltage for the RESS 115, switches 102 and 103 may be closed and switch 104 may be open, meaning boost operation is not used.

[0036] As in the Fig. 2A to 3, the electrical system 100 further includes an inverter controller 180 that controls the operation of the semiconductor switches S1 to S6 of the inverter 162, which will be described below with reference to the Fig. 2A through 3. The inverter controller 180 may include at least one processor and sufficient memory for storing computer-readable instructions. The memory includes tangible, non-transferable memory, such as read-only memory, whether optical, magnetic, flash memory, or other. The inverter controller 180 also includes sufficient amounts of random access memory, electrically erasable programmable read-only memory, and the like, as well as a high-speed clock, analog-to-digital and digital-to-analog circuitry and input / output circuitry and devices, and suitable signal conditioning and buffering circuitry.

[0037] In one example implementation, inverter controller 180 may receive signals from controller 150 and / or from sensors within inverter and traction motor 114. The sensors may be, for example, phase current sensors and / or rotor position sensors and may provide signals indicative of a phase current and / or a position of the rotor. Inverter controller 180 may control semiconductor switches S1 through S6 by providing a signal to one or more gates to cause semiconductor switches S1 through S6 to transition between an open state and a closed state, as described in more detail below.

[0038] Fig. 3 shows an example schematic diagram of the electrical system 100. The inverter 162 may include a bidirectional DC-to-AC and AC-to-DC power converter, which may be part of a traction power inverter module (TPIM) that connects the off-board power source, e.g., the off-board DC fast charging station 30 or another vehicle, to the RESS 115 via inductor windings 167. As shown, the electrical system 100 includes a plurality of machine windings 166 and a plurality of inductor windings 167 that are magnetically decoupled from the machine windings and may be disposed within the inverter or battery assembly on a heat sink for cooling.

[0039] In one example implementation, the machine windings 166 include windings, e.g., machine windings, of the traction motor 114. During operation of the vehicle 20, the machine windings 166 may, for example, provide three-phase current to generate a rotating magnetic field and rotate a rotor of the traction motor 114. Although only three machine windings 166 are shown in the figure, the traction motor 114 may include additional machine windings 166 depending on the motor configuration. The inverter 162 may include multiple phases and corresponding motor control modules that can receive motor control commands and control inverter states to provide motor drive or regeneration functions. In one example implementation, the machine windings 166 may include the machine windings La, Lb, Lc.

[0040] The inductor windings 167 may comprise a plurality of inductor windings arranged in Fig. 3 as inductor windings Lx, Ly, Lz, and can amplify a voltage supplied to the RESS 115 via the off-board power source, as explained in more detail below. In some embodiments, the inductor windings Lx, Ly, Lz can be arranged, e.g., wound, around separate magnetic cores. In other embodiments, the inductor windings Lx, Ly, Lz can be arranged around a single, e.g., common, magnetic core to minimize mass and volume within the vehicle 20.

[0041] As in Fig. 3, the electrical circuit also includes a first set of switches 156 and a second set of switches 158. The first set of switches 156 may include at least a first switch Sa, a second switch Sb, and a third switch Sc. The switches Sa, Sb, and Sc may be disposed between the corresponding machine windings La, Lb, or Lc of the machine windings 166 and the inverter 162. The switches Sa, Sb, and Sc may be actuated by the controller 150 to supply electrical power to the traction motor 114 during vehicle operation and to prevent electrical power from being supplied to the traction motor 114 during a charging operation.

[0042] The second set of switches 158 may include switches Sx, Sy, Sz and may be arranged between a corresponding one of the inductor windings Lx, Ly, or Lz of the inductor windings 167 and the off-board power source when the off-board power source is connected to the vehicle 20. The switches Sx, Sy, and Sz may be actuated by the control unit 150 to supply electrical power to the RESS 115 during charging and prevent electrical power from being drawn from the RESS during vehicle operation and / or when the off-board power source is disconnected. In one embodiment, the switch groups 156 and 158 may include contactors, e.g., relays. In one embodiment, the switch groups 156, 158 may be replaced with single-pole, double-throw (SPDT) switches.

[0043] The inverter 162 may include a set 164 of semiconductor switches S1 through S6 (also referred to herein as “inverter switches”) that cooperate to convert direct current (DC) from the RESS 115 to alternating current (AC) to operate the traction motor 114 in a motoring or braking mode via high frequency switching. Each semiconductor switch S1 to S6 may be a voltage-controlled switching device in the form of at least one of a silicon insulated gate bipolar transistor (IGBT), a silicon carbide (SiC) metal oxide semiconductor field-effect transistor (MOSFET), a silicon (Si) superjunction MOSFET, a gallium nitride (GaN) field-effect transistor (FET), a SiC field-effect transistor with junction (JFET), another wideband gap (WBG) or ultra-wideband gap (UWBG) semiconductor power switch, or another suitable switch having a corresponding gate to which a gate signal is applied to change the on / off state of a particular switch.Typically, there is at least one pair of semiconductor switches for each phase of the three-phase traction motor 114. Each pair of switches, e.g., switches S1 and S2 (phase A), switches S3 and S4 (phase B), and switches S5 and S6 (phase C), may be referred to as a phase leg of the inverter 162. For example, in one example implementation, the inverter 162 may include at least three (3) phase legs. Each phase leg of the inverter 162 is connected to a corresponding phase terminal of the machine, e.g., to one of the machine windings 166.

[0044] As in Fig. 3, the off-board power source, e.g., charger 30 or another vehicle, may be adapted to supply converted electrical energy to the RESS 115 during the charging process. For example, the electrical system 100 may boost a voltage supplied by the off-board power source. The battery pack 116 may be configured to store a voltage having the first voltage higher than the second voltage, e.g., the first voltage may be eight hundred (800) VDC and the second voltage may be four hundred (400) VDC. During this operating condition, e.g., a charging process, switches S1, S3, and S5 may be in an open state to prevent current flow through the corresponding switch. At least one of switches S2, S4, or S6 may be supplied with a pulse-width modulated control signal to enable current flow from the external charging source to the RESS 115.During the boost charging process, the controller 150 may also cause the corresponding winding, e.g., the inductor winding Lx, Ly, or Lz of the inductor windings 167, as well as the corresponding switch Sx, Sy, or Sz, to be in a closed state to establish an electrical connection between the off-board charging source and the RESS 115.

[0045] The inductances of the inductor windings Lx, Ly, Lz and the corresponding freewheeling diodes feeding the inverter 162 can operate as a nested three-phase boost converter. It is understood that by using inductor windings that are magnetically decoupled from the machine windings, there is no impact on the machine torque, as it is switched off during boost operation. The controller 150 and / or the inverter controller 180 can select an optimal duty cycle and phase shift of the inverter phases to provide the requested charging current with minimal current ripple during the boost converter function. For example, the controller 150 and / or the inverter controller 180 can use a lookup table based on one or more vehicle parameters, e.g., charging current, voltage, etc., and output a PMW signal corresponding to the vehicle parameters to cause the second set of switches 158 and / or one or more inverter switches S1 through S6 to operate as described above. For example, based on the switch selection, a desired boost converter function may be selected to charge the RESS 115 and minimize charging current ripple.

[0046] In various implementations, the controller 150 and the inverter controller 180 may modulate control signals provided to the second set of switches 158 and / or the switches of the power inverter 162. For example, during a charging operation, the control signals may be modulated such that electrical energy is supplied to the RESS 115 via the inductor winding Lx and the switch S1 during a first period of time, electrical energy is supplied to the RESS 115 via the inductor winding Ly and the switch S3 during a second period of time, and electrical energy is supplied to the RESS 115 via the inductor winding Lz and the switch S5 during a third period of time. It is understood that the controller 150 may include various control schemes to allow the voltage supplied by the off-board power source to be converted to a higher voltage, e.g., from the first voltage to the second voltage.

[0047] During a charging process, the energy stored in one of the machine windings Lx, Ly, Lz is transferred to the RESS 115 via a corresponding freewheeling diode of the inverter switches 162. In this way, the machine's phase windings 167, in conjunction with the inverter's phase leg switches, can increase the first voltage to the second voltage, e.g., performing a boost conversion. In an implementation where the inverter switches consist of MOSFETs, the complementary switch can be turned on in each phase when the lower switch is turned off during boost conversion operation to minimize freewheeling diode losses.

[0048] In some implementations, the software for the controller 150 may be updated based on over-the-air programming. For example, software updates may be transmitted to the controller 150 from a data source, such as an original equipment manufacturer (OEM), via one or more suitable communication networks. The over-the-air updates may provide the desired parameters for adjusting the charging power by adjusting the inverter control signals, such as current setpoint, frequency, duty cycle, phase shift, etc., for one or more switches S1 through S6 according to a charging power level via the inverter controller 180.

[0049] Fig.4 is a flowchart of an exemplary process 400 for providing power to the RESS 115 of the vehicle 20 from an off-board power source. The blocks of process 700 may be executed by the controller 150 and / or the inverter controller 180. In block 405, it is determined whether an electrical connection has been established between an off-board power source and the high-voltage DC bus 160. For example, the controller 150 may receive an input signal indicating a charging operation through appropriate handshaking protocols and / or signals with the controller of the external power source and establishes the electrical connection. If the electrical connection has not been established, the program 400 returns to block 405.

[0050] Once the electrical connection has been established, the controller 150 sends one or more control signals to the inverter 162, the switches 102, 103, 104, and the first and second sets of switches 156, 158 in block 410. Based on the input signal from the controller 150, the switches 102, 103, 104, and / or 105 transition to a desired operating state, e.g., the open state or the closed state, and the inverter controller 180 outputs voltage signals that cause the switches S1 through S6 of the inverter 162 to provide the boost function. For example, switch 102 may transition to the open state to prevent current flow from the off-board power source to RESS 115, and switch 103 may transition to the closed state to allow current flow from the off-board power source to inductor windings 167, e.g.the boost inductor windings, to increase the voltage supplied to the RESS 115. The switches of the inverter 162 can be modulated while the corresponding second set of switches 158 remains closed to increase the voltage at the RESS 115 due to the boost converter function causing current to flow through the inductor windings 167.

[0051] In block 415, the controller 150 determines whether the electrical connection to the off-board power source has been disconnected or the RESS charging process is complete. For example, the controller 150 may receive a signal indicating that the plug of the charging cable 15 has been disconnected from the charging port 11 or that the RESS charging process is complete. If the controller 150 has not determined that the electrical connection has been disconnected or that the RESS charging process is complete, the process 400 returns to block 415. Otherwise, the process 400 terminates.

Claims

[1] Electrical system comprising: a rechargeable energy storage system (RESS) (115); an inverter (162) connected to the RESS (115), the inverter (162) configured to supply electrical energy to a traction motor (114); a plurality of machine windings (166) connected between a plurality of first switches (156) and the traction motor (114), each switch (Sa-Sc) of the plurality of first switches (156) being configured to transition between a closed state to allow current flow between the inverter (162) and the traction motor (114) and an open state to prevent current flow between the inverter (162) and the traction motor (114); and a plurality of inductor windings (167) connected between a plurality of second switches (158) and an off-board power source (30), each switch (Sx-Sz) of the plurality of second switches (158) being configured to transition between a closed state to allow current flow between the off-board power source (30) and the inverter (162) for charging the RESS (115) and an open state to prevent current flow between the off-board power source (30) and the inverter (162). [2] The electrical system of claim 1, wherein each winding of the plurality of machine windings (166) comprises windings of the traction motor (114). [3] The electrical system of claim 1, wherein each winding of the plurality of inductor windings (167) is arranged around a common magnetic core that is magnetically decoupled from the machine. [4] The electrical system of claim 1, wherein each winding of the plurality of inductor windings (167) is arranged around a different magnetic core, each of which is magnetically decoupled from the machine. [5] The electrical system of claim 1, wherein the inverter (162) comprises a series of semiconductor switches (S1-S6) configured to convert direct current (DC) to alternating current (AC). [6] The electrical system of claim 5, wherein each semiconductor switch (S1-S6) of the semiconductor switch set comprises a voltage controlled switching device. [7] The electrical system of claim 6, wherein the voltage controlled switching device comprises at least one of a silicon insulated gate bipolar transistor (IGBT), a silicon carbide metal oxide semiconductor field effect transistor (MOSFET), a silicon superjunction MOSFET, a gallium nitride field effect transistor (FET), a SiC junction gate field effect transistor (JFET), a wide band gap (WBG) device, or an ultra wide band gap (UWBG) device. [8] The electrical system of claim 5, wherein the inverter (162) comprises a plurality of phase legs, each phase leg of the plurality of phase legs comprising a pair of semiconductor switches (S1, S2; S3, S4; S5, S6) of the set of semiconductor switches (S1-S6), each phase leg being selectively connected to a corresponding one of the plurality of machine windings (166) or the plurality of inductor windings (Lx, Ly, Lz). [9] Electrical system according to claim 8, wherein at least one semiconductor switch (S1-S6) of at least one phase leg is pulse width modulated to enable current flow through at least one of the phase legs and the corresponding choke coil winding to the RESS (115) from the off-board power source (30). [10] The electrical system of claim 9, wherein current flows through at least one inductor winding (Lx, Ly, Lz) of the plurality of inductor windings (167) to increase a voltage from the off-board power source (30) from a first voltage to a second voltage.

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