HIGH-VOLTAGE / LOW-VOLTAGE CHARGING ARCHITECTURE SUPPORTING UNINTERRUPTED LOW-VOLTAGE SOURCE SUPPLY UNDER TRACTION BATTERY SINGLE-POINT FAULTS

Abstract

An automotive power system includes a bidirectional power factor correction circuit having line and neutral terminals connectable to an AC source, a traction battery having positive and negative terminals and a center point, and an isolated DC / DC converter connected between the bidirectional power factor correction circuit and the traction battery.

Description

FIELD OF TECHNOLOGYThis disclosure relates to automotive power systems.GENERAL STATE OF THE ARTAn automobile may use electrical energy to power an electric machine. The electric machine may convert this electrical energy to mechanical energy to propel the vehicle. The motor vehicle may include various power electronics equipment to condition and store the electrical energy.SUMMARYA vehicle includes a bidirectional power factor correction circuit having grid and neutral terminals connectable to an AC source, a traction battery having positive and negative terminals and a midpoint, an isolated DC / DC converter connected between the bidirectional power factor correction circuit and the traction battery, and a plurality of switches selectively connecting the positive and negative terminals directly to the grid terminals and the midpoint directly to the neutral terminal.A method includes, after disconnecting grid and neutral terminals associated with a bi-directional power factor correction circuit of a vehicle from an AC source, directly connecting the grid terminals to positive and negative terminals of a traction battery of the vehicle and the neutral terminal to a midpoint of the traction battery such that power flows from the traction battery through the bi-directional power factor correction circuit to an isolated DC / DC converter connected between the bi-directional power factor correction circuit and the traction battery.An automotive power system includes a bidirectional power factor correction circuit having line and neutral terminals connectable to an AC source, a traction battery having positive and negative terminals and a midpoint, an isolated DC / DC converter connected between the bidirectional power factor correction circuit and the traction battery, and a controller. The controller connects the positive and negative terminals directly to the grid terminals and the midpoint directly to the neutral terminal during a drive mode such that power from the traction battery flows through the bidirectional power factor correction circuit and to the isolated DC / DC converter.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a schematic illustration of a system including a battery current control module. FIG. 2 is a schematic illustration of a system including an inverter system controller. FIG. 3 is a schematic illustration of a vehicle including an integrated battery current control module and an inverter system controller. FIG. 4 is a schematic illustration of a vehicle including an on-board charger and a high voltage / low voltage magnetically integrated DC / DC converter. FIG. 5 is a schematic illustration of a vehicle including a proposed high voltage / low voltage battery charging architecture.DETAILED DESCRIPTIONEmbodiments are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments may take various and alternative forms. The figures are not necessarily to scale. Some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art.Various features illustrated and described with respect to any of the figures may be combined with features illustrated in one or more other figures to produce embodiments that are not expressly illustrated or described. The illustrated combinations of features provide representative embodiments for typical applications. However, various combinations and modifications of the features consistent with the teachings of this disclosure may be desirable for specific applications or implementations.Battery current control modules (BCCMs) are components in motor vehicles, in particular those with electric or hybrid drive trains. These modules play a role in managing the flow of electric power to and from the battery. BCMs function as controllers that interface the battery, charging system, and electrical loads. They monitor and control various parameters such as charge state, voltage and temperature of the battery, and manage the flow of current to the battery based on this information. BCCMs can facilitate charge control by supervising the charging process of the battery and managing the voltage and current supplied by the charging system. By monitoring the state of charge of the battery and adjusting the charging parameters accordingly, BCCMs attempt to ensure that the battery receives the appropriate level of charge to maintain performance. Likewise, BCCMs may be responsible for discharge control. They can manage the power output from the battery to the electric loads in the vehicle. By controlling the current flow, BCCMs may ensure controlled power delivery to the various electrical components and systems. BCCMs may also implement various measures for the battery. For example, they may monitor the battery temperature to prevent overheating. They can also detect overvoltage or undervoltage situations and implement measures to exclude short circuits or excessive current consumption. BCCMs may have diagnostic capabilities. These modules may monitor the state and performance of the battery system. They can log codes and provide diagnostic information, which facilitates maintenance.Communication interfaces are often included in BCCMs. These interfaces, such as a controller area network (CAN) or local interconnect network (LIN), allow BCMs to exchange information with other vehicle systems that include the engine control unit (ECU) or the body control module (BCM). This allows coordinated operation and integrated control across various vehicle functions. BCCMs may receive commands or instructions from other controllers and adjust current flow accordingly.Inverter system controllers (ISCs) are also components in motor vehicles with electrical powertrains. They play a role in managing and controlling the power flow between the battery and the electric motor. One function of an inverter system controller is to convert direct current (DC) from the battery to alternating current (AC) to power the electric motor. ISCs can act as decision substrates for the power electronics system. It may monitor various parameters such as speed, torque, and temperature of the electric motor to ensure operation. An object of ISCs is to convert DC power from the battery into three-phase AC power suitable for the electric motor. It may use high power semiconductor devices, for example insulated-gate bipolar transistors (IGBTs), to control the switching of current and voltage. By modulating the pulse width and frequency of the AC waveform, the inverter system controller manages the speed and torque output of the electric motor. ISCs may provide control of the electric motor. They may use algorithms and control strategies to manage the speed, torque, and direction of rotation of the electric motor. By adjusting the switching patterns of the IGBTs, the controller may vary the frequency and amplitude of the AC waveform, which changes the motor operation. ISCs may facilitate regenerative braking. During deceleration or braking, the electric motor operates as a generator that converts the kinetic energy of the vehicle into electrical energy. The inverter system controller may control the flow of energy while passing it back to the battery for storage. ISCs may be responsible for managing the thermal conditions of the power electronics system. They may monitor the temperature of the inverter and the electric motor and utilize cooling systems such as fans, liquid cooling, or heat sinks to dissipate excess heat and maintain operating temperatures. ISCs may incorporate diagnostic capabilities to detect and protect against faults in the power electronics system. They may monitor various parameters, such as voltage, current, and temperature values, that could indicate a potential fault. If an error is detected, the controller may take corrective action, such as shutting down the system, turning on other action, or providing error codes for diagnostic purposes. ISCs may incorporate features such as overvoltage and undervoltage monitoring, overcurrent monitoring, and isolation monitoring.ISCs often have communication interfaces, such as CAN or Ethernet, that enable integration with other vehicle systems. They can exchange information with the main control unit, which allows coordinated operation and facilitates diagnosis and fault correction. Communication interfaces also allow the controller to receive commands or instructions from the electronic control unit (ECU) and adjust the power output accordingly.Integrating the BCCM into the ISC is conventionally considered a challenge due to the isolation circuit. The schematics of typical separate systems 10, 12 are shown in Figures 1 and 2, respectively.Referring to FIG. 1, the system 10 includes a BCCM 14, a traction battery 16, an auxiliary battery 18, and an on-board charge controller 20. the BCCM includes an AC / DC power factor correction circuit 22, a high-voltage insulated DC / DC circuit 24, an intermediate circuit capacitor 26, and a high-voltage-low-voltage insulated DC / DC circuit 28. the high-voltage insulated DC / DC circuit 24 is connected between the AC / DC power factor correction circuit 22 and the intermediate circuit capacitor 26. The DC link capacitor 26 is connected between the high voltage insulated DC / DC circuit 24 and the high voltage insulated low voltage DC / DC circuit 28. The traction battery 16 and the auxiliary battery 18 are connected to the high-voltage-low-voltage insulated DC / DC circuit 28.The AC / DC power factor correction circuit 22 includes an electromagnetic interference filter 30, a switch bank 32, and an AC / DC power conversion circuit 34.The high voltage insulated DC / DC circuit 24 includes a first jumper 36, a transformer 38, and a second jumper 40. The transformer 38 is connected between the first and second jumpers 36, 40.The high-voltage-low-voltage DC / DC insulated circuit 28 includes an electromagnetic interference filter 42, a capacitor 44, and a high-voltage-low-voltage power converter circuit 46. the electromagnetic interference filter 42 is connected across the capacitor 44 and directly connected to the traction battery 16. The capacitor 44 is connected between the intermediate circuit capacitor 26 and the high-voltage-low-voltage power conversion circuit 46. The high voltage to low voltage power converter circuit 46 is directly connected to the auxiliary battery 18. The on-board charge controller 20 is in communication with and / or exercises control over the components of FIG. 1.Referring to FIG. 2, the system 12 includes an electric machine 48, an ISC 50, and a traction battery 52. the ISC 50 is connected between the electric machine 48 and the traction battery 52.The ISC 50 includes a three-phase inverter configured to drive the electric machine 48 and operates at a much higher power than the BCCM 14. The BCCM 14 also includes three circuits configured as three-phase inverters / rectifiers. Two isolation circuits are required to utilize the three-phase inverter of the ISC in charging / discharging the traction battery 16. The first disconnect circuit is used to disconnect the electric motor 48 from the ISC 50 and the second disconnect is used to disconnect the ISC 50 from the traction battery 52. The contactors used in these isolation circuits must carry the full current of the ISC. The addition of these contactors increases the number of components required - which makes integration at the electrical level unfavourable. However, package level integration may provide advantages as it reduces the overall size and / or weight of the package and the number of connectors and wires. The schematics of such a system 54 are shown in FIG. 3 in the context of a vehicle 55.Referring to FIG. 3, the system 54 includes an electromagnetic interference filter 56, a switch bank 58, an AC / DC power converter 60, a jumper 62, a capacitor bank 64, a transformer 66, a capacitor bank 68, a switch bank 70, an electric machine 72, a jumper 74, a traction battery 76, and a controller 78.The switch bank 58 is connected between the electromagnetic interference filter 56 and the AC / DC power converter 60. The jumper 62 is connected between the AC / DC power converter 60 and the capacitor bank 64. The transformer 66 is connected between the capacitor banks 64, 68. Capacitor bank 68 is connected between the transformer and switch bank 70. The transformer 66 is thus also connected between the switching bridge 62 and the switch bank 70. The jumper 74 is connected between the electric machine 72 and the traction battery 76. The controller 78 is in communication with and / or exercises control over the components of FIG. 3.The switch bank 70 is connected to a secondary side of the transformer 66: when switches of the switch bank 70 are closed, the transformer 66 is connected between the electric machine 72 and the jumper 74 such that the jumper 62, the transformer 66, the electric machine 72, and the jumper 74 form an isolated DC / DC power converter. The controller 78 may close the switches of the switch bank 70 in response to a request to charge the traction battery 76. When closed, energy received from, for example, a grid at the electromagnetic interference filter 56 via L 1, L 2, L 3, and N may be conditioned and transferred to the traction battery 76 by the now formed isolated DC / DC power converter. The controller 78 may operate switches of the AC / DC power converter 60 and the switching bridges 62, 64 at 300 kHz, for example, when the switches of the switch bank 70 are closed (i.e., during the charging mode). When charging is completed, the controller 78 may open the switches of the switch bank 70. The controller 78 may operate the switches of the jumper 64 at, for example, 30 kHz (or less) when the switches of the switch bank 70 are open (e.g., during the driving mode). Other shift speeds may of course be used.The circuit topology illustrated in FIG. 3 enables integrating a BCCM (the electromagnetic interference filter 56, the switch bank 58, the AC / DC power converter 60, the jumper 62, the capacitor bank 64, the transformer 66, the capacitor bank 68, and the switch bank 70) with an ISC without using high current contactors. The accessory circuit directly interfaces with the ISC without disconnecting the electric machine or the traction battery. The accessory circuit includes a front-end AC / DC power factor correction circuit and portions of the high voltage insulated DC / DC circuit that is part of the BCCM. Three relays are added to disconnect the accessory circuit from the ISC during the drive mode. The high voltage DC / DC circuit of the BCCM may be configured in consideration of the stator winding impedance of the electric machine and its variations in rotor position. When the vehicle is connected to the AC grid, the accessory circuit, the ISC, and the electric motor form an AC / DC-DC / AC bidirectional power converter. The high voltage DC / DC power converter of the BCCM may be configured to switch at a frequency that is much higher than the switching frequency of the ISC.In some circumstances, the 12V battery may serve as a second power source to ensure the uninterrupted functioning of systems when the traction battery 76 is not available. It may also send power to keyless consumers, such as the central locking system. Removing the 12V battery may be advantageous in some circumstances. However, functional requirements and normal vehicle functionality should be met as if the 12V battery were present.Referring to FIG. 4, a system 80 includes an on-board charger and a high-voltage / low-voltage magnetically-integrated DC / DC converter 82, high-voltage loads 84, a switch bank 86, a traction battery 88, and a low-voltage battery 90 (e.g., 12V battery). The system 80 is shown in the context of the vehicle 91.The on-board charger and high voltage / low voltage magnetically integrated DC / DC converter 82 are connected between an AC source 92 (if present) and high voltage loads 84. The high voltage loads 84 are connected between the onboard location device and the high voltage / low voltage magnetically integrated DC / DC converter 82 and the switch bank 86. The switch bank 86 is connected between the high voltage loads 84 and the traction battery 88.The on-board charger and high voltage / low voltage magnetic integrated DC / DC converter 82 include a one / three phase bi-directional totem pole power factor correction circuit 94 and a three terminal insulated DC / DC converter 96. The one / three phase bi-directional totem pole power factor correction circuit 94 is connected between the AC source 92 and the three terminal insulated DC / DC converter 96. The three terminal insulated DC / DC converter 96 is connected between the one / three phase bi-directional totem pole power factor correction circuit 94 and the high voltage loads 84.The one / three phase bi-directional totem pole power factor correction circuit 94 includes a switch bank 98 and an AC / DC power converter 100. The switch bank 98 is connected between the AC source 92 (if present) and the AC / DC power converter 100. The AC / DC power converter 100 is connected between the switch bank 98 and the three terminal insulated DC / DC converter 96.The three terminal insulated DC / DC converter 96 includes a jumper 102, a transformer 104, a jumper 106, an DC link capacitor 108, and a rectifier 110. The jumper 102 is connected between the AC / DC power converter 100 and the transformer 104. The transformer 104 is connected between the switching bridges 102, 106, the switching bridge 106 is connected between the transformer 104 and the intermediate circuit capacitor 108. The DC link capacitor 108 is connected between the jumper 106 and the high voltage loads 84. The rectifier 110 is magnetically coupled to the transformer 104 via a low voltage coil and a common core. The low voltage battery 90 is connected to the rectifier 110.When the low voltage battery 90 is removed, a single point problem could disconnect the high voltage bus from the power grid and interrupt low voltage power supply to the loads. This is because the low voltage battery 90 is no longer used as a backup. In certain systems, the power to the low voltage components should not be interrupted and remain above a threshold even if the traction battery voltage drops below what the high voltage / low voltage DC / DC converter 96 may support. Additionally, the low voltage battery 90 should be able to support the loads when the high voltage / low voltage DC / DC converter 96 is no longer available. Removing the battery of the low voltage battery 90 may result in other countermeasures. There is a need for an architecture that enables the removal or significant downsizing of the low voltage battery 90 while minimizing hardware addition.Referring to FIG. 5, a system 111 includes a controller 112, an on-board charger, and a high-voltage / low-voltage magnetically-integrated DC / DC converter 114, a switch bank 116, high-voltage loads 118, a switch bank 120, a traction battery 122, and a low-voltage battery 124 (e.g., 12V battery). The system 111 is shown in the context of the vehicle 125. The controller 112 is in communication with and / or exercises control over the components of FIG. 5.The on-board charger and high voltage / low voltage magnetically integrated DC / DC converter 114 are connected between an AC source 126 (if present) and the switch bank 116. The switch bank 116 is connected between the onboard location device and the high / low voltage magnetically integrated DC / DC converter 114 and the high voltage loads 118. (That is, at least some switches of the switch bank 116 have at least one terminal connected between the on-board charger and the high / low voltage magnetically integrated DC / DC converter 114 and the high voltage loads 118). The high voltage loads 118 are connected between the switch banks 116, 120. The switch bank 120 is connected between the high voltage loads 118 and the traction battery 122.The on-board charger and high voltage / low voltage magnetic integrated DC / DC converter 114 include a bidirectional power factor correction circuit (e.g., a one / three phase bidirectional totem pole power factor correction circuit) 128 and an isolated DC / DC converter (e.g., a three terminal isolated DC / DC converter) 130. The one / three phase bi-directional totem pole power factor correction circuit 128 is connected between the AC source 126 (if present) and the three terminal isolated DC / DC converter 130. The insulated terminal DC / DC converter 130 is connected between the one / three phase bi-directional totem pole power factor correction circuit 128 and the switch bank 116.The bi-directional totem pole power factor correction circuit 128 includes a switch bank 132 and an AC / DC power converter 134. The switch bank 132 is connected between the AC source 126 (if present) and the AC / DC power converter 134. The AC / DC power converter 134 is connected between the switch bank 132 and the three terminal isolated DC / DC converter 130.The three terminal insulated DC / DC converter 114 includes a jumper 136, a transformer 138, a jumper 140, an DC link capacitor 142, and a rectifier 144. The jumper 136 is connected between the AC / DC power converter 134 and the transformer 138. The transformer 138 is connected between the jumpers 136, 140, and the jumper 140 is connected between the transformer 138 and the DC link capacitor 142. The intermediate circuit capacitor 142 is connected between the switching bridge 140 and the switch bank 116. Rectifier 144 is magnetically coupled to transformer 138 via a low voltage coil and a common core. The low voltage battery 124 is connected to the rectifier 144.The switch bank 132 includes switches SW 1, SW 2, SW 3, SW 4, SW 5, SW 6. The AC / DC power converter 134 includes branch 1, branch 2, branch 3, inductors I 1, I 2, I 3, series switches SW 7, SW 8, and series capacitors C 1, C 2. The node A is shared by terminals of the capacitors C 1, C 2 and one terminal of the switch SW 8. The switch bank 120 includes switches SW 9, SW 10, SW 15. The switch bank 116 includes switches SW 11, SW 12, SW 13, SW 14 (e.g., relays).The on-board charger circuit is thus used to construct a high-voltage to low-voltage DC / DC converter with three input terminals. The traction battery 122 is divided into two halves, with the switch SW 9 disconnecting the positive terminal of the traction battery from the high voltage bus and the switch SW 10 disconnecting the negative terminal of the traction battery from the high voltage bus. The switch SW 15 is added to the battery pack to disconnect the center of the battery from the high voltage system.When the vehicle 125 is not connected to the AC grid source 126 or is in the drive mode, the AC input of the on-board charger is connected to the three terminals of the traction battery by configuring the switch banks 116, 120, 132 as follows. In normal operation, the switches SW 9, SW 10, SW 15 are closed. The switches SW 2, SW 4 are opened to allow each respective phase of the AC / DC power converter 134 to be connected to a different input source. The switch SW 12 is opened to disconnect the on-board charger secondary rectifier 140 from the traction battery 122. Only the positive bus is open, while the negative bus is still connected to the traction battery 122. Alternatively, the switch SW 12 may be connected such that the negative bus is disconnected from the traction battery 122 while the high voltage bus remains connected. The switches SW 1, SW 11 are closed to connect the positive terminal of the traction battery to L 1 (line 1). The switches SW 3, SW 13 are closed to connect the negative terminal of the traction battery to L 2 (line 2). Switches SW 6, SW 14 are closed while switch SW 5 is open to allow the traction battery midpoint to be connected to N (neutral). Switch SW 8 is closed while switch SW 7 is open to connect the neutral and midpoint of the traction battery to point A.The AC / DC power stage 134 acts as a boost converter that steps up the voltage of each half of the traction battery 122. Two bi-directional active half bridge rectifiers are formed by branch 1 and branch 2. A bidirectional down / up converter is formed by branch 3. Current flowing through the inductor I 3 is controlled to ensure that the neutral voltage is centered between the high voltage DC rails. That is, the voltage across C1 and C2 is equalized (VC1=VC2=Vbus / 2). To ensure voltage balance across C 1 and C 2, the buck / boost converter has two modes of operation: (1) buck mode (when VC 2<Vbus / 2) in which it is supplying current to charge C 2 (this condition occurs when switch SW 10 is opened due to a single point problem in the traction battery 122); (2) boost mode (when VC 2>Vbus / 2) in which it is drawing current to discharge C 2 (this condition occurs when switch SW 9 is opened due to a single point problem in the traction battery 122). A single point fault requiring either switch SW9 or switch SW10 to open does not interrupt the DC link voltage (Vbus).A high-voltage to low-voltage DC / DC converter is formed by switching the primary bridge 136 with respect to the high-voltage AC side and the secondary bridge 140 with respect to the low-voltage DC side. The primary high voltage AC side bridge 136 and the secondary low voltage DC side bridge 140 are magnetically coupled by the transformer 138. The high voltage AC bridge 136 is responsible for receiving a DC input and outputting an AC voltage / current to power a primary winding of the transformer 138. The high voltage DC bridge 140 is responsible for receiving an AC voltage and current at its input and converting them to DC voltage or current using inductive or capacitive filter components.Reverse power may flow from the low voltage battery 124 to the traction battery 122 by operating the high voltage DC bridge 140 as an inverter and operating the high voltage AC bridge 136 as a rectifier.When the vehicle 125 is connected to the AC source 126 for charging the traction battery 122, a low voltage output is provided by the three terminal transformer 138 by magnetically coupling the low voltage coil of the rectifier 144 to a coil of the transformer 138 that is related to the high voltage AC side and a coil of the transformer 138 that is related to the high voltage DC side.The closing of the switches SW 11, SW 13, SW 14, SW 15 requires the AC terminal of the vehicle to be closed because high voltage DC is applied across the AC pins. When this locking mechanism is not implemented, additional relays may be added to disconnect the AC pins from the traction battery 122 while the vehicle 125 is in the drive mode or is not connected to the AC source 126.During grid-to-vehicle or vehicle-to-grid operations, switches SW 11, SW 13, SW 14, SW 15 are open while switch SW 12 is closed.The algorithms, methods, or processes disclosed herein may be executable by a computer, controller, or processing device, which may include, or be implemented by, any dedicated electronic control unit or programmable electronic control unit. Additionally, the algorithms, methods, or processes may be stored in many forms as computer or controller executable data and instructions including, without limitation, information permanently stored on non-writable storage media such as read-only memory devices and information alterably stored on writeable storage media such as compact discs, random access memory devices, or other magnetic and optical media. The algorithms, methods, or processes may also be implemented in software executable objects. Alternatively, the algorithms, methods, or processes may be implemented in whole or in part using suitable hardware components, such as application specific integrated circuits, field programmable gate arrays, state machines, or other hardware components or devices, or a combination of firmware, hardware, and software components.While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The terms used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of these disclosed subject matters. The terms "controller" and "controllers" may be used interchangeably herein, for example, because the functionality of a controller may be distributed across multiple controllers / modules, all of which may communicate via standard techniques.As previously described, the features of various embodiments may be combined to form further embodiments of the invention that may not be expressly described or illustrated. While various embodiments could have been described as providing or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art will understand that one / more features or characteristics may be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes may include, but are not limited to, strength, durability, marketability, appearance, building, size, serviceability, weight, magnetoresistance, ease of assembly, etc. Thus, embodiments described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and may be desirable for particular applications.According to the present invention, there is provided a vehicle comprising: a bidirectional power factor correction circuit having grid and neutral terminals configured to be connected to an AC source; a traction battery having positive and negative terminals and a midpoint; an isolated DC / DC converter connected between the bidirectional power factor correction circuit and the traction battery; and a plurality of switches configured to selectively connect the positive and negative terminals directly to the grid terminals and the midpoint directly to the neutral terminal.According to one embodiment, the bidirectional power factor correction circuit is a bidirectional totem pole power factor correction circuit.According to an embodiment, the isolated DC / DC converter is a three terminal isolated DC / DC converter.According to an embodiment, the invention is further characterized by an auxiliary battery directly connected to the three-terminal insulated DC / DC converter.According to an embodiment, the insulated three terminal DC / DC converter includes a transformer and a rectifier magnetically coupled to the transformer.According to an embodiment, the isolated three terminal DC / DC converter is configured to selectively transfer power from the auxiliary battery to the traction battery.According to an embodiment, the invention is further characterized by a controller programmed to, in response to the grid and neutral terminals being connected to an AC source, disconnect the positive and negative terminals from the grid terminals and disconnect the midpoint from the neutral terminal.According to the present invention, a method includes: after disconnecting grid and neutral terminals associated with a bi-directional power factor correction circuit of a vehicle from an AC source, directly connecting the grid terminals to positive and negative terminals of a traction battery of the vehicle and the neutral terminal to a midpoint of the traction battery such that power flows from the traction battery through the bi-directional power factor correction circuit to an isolated DC / DC converter connected between the bi-directional power factor correction circuit and the traction battery.In one aspect of the invention, the method includes disconnecting the power terminals from the positive and negative terminals and the neutral from the midpoint such that power from the AC source, when connected to the power and neutral terminals, flows through the bidirectional power factor correction circuit and the isolated DC / DC converter to charge the traction battery.In one aspect of the invention, the method includes operating the isolated DC / DC converter to transfer power from an auxiliary battery connected to the isolated DC / DC converter to the traction battery.According to the present invention, there is provided an automotive power system comprising: a bidirectional power factor correction circuit having grid and neutral terminals configured to be connected to an AC source; a traction battery having positive and negative terminals and a midpoint; an isolated DC / DC converter connected between the bidirectional power factor correction circuit and the traction battery; and a controller programmed to directly connect the positive and negative terminals to the grid terminals and the midpoint to the neutral terminal during a drive mode such that power flows from the traction battery through the bidirectional power factor correction circuit and to the isolated DC / DC converter.According to an embodiment, the controller is further configured to disconnect the positive and negative terminals from the grid terminals and the midpoint from the neutral terminal during a charging mode such that power from an AC source flows through the bidirectional power factor correction circuit and the isolated DC / DC converter to charge the traction battery.According to an embodiment, the invention is further characterized by an auxiliary battery connected to the isolated DC / DC converter.According to an embodiment, the controller is further programmed to operate the isolated DC / DC converter to transfer power from the auxiliary battery to the traction battery.According to an embodiment, wherein the bidirectional power factor correction circuit is a bidirectional totem pole power factor correction circuit.According to an embodiment, the isolated DC / DC converter is a three terminal isolated DC / DC converter.According to an embodiment, the insulated three terminal DC / DC converter includes a transformer and a rectifier magnetically coupled to the transformer.

Claims

A vehicle comprising: a bidirectional power factor correction circuit having grid and neutral terminals configured to be connected to an AC source; a traction battery having positive and negative terminals and a midpoint; an isolated DC / DC converter connected between the bidirectional power factor correction circuit and the traction battery; and a plurality of switches configured to selectively connect the positive and negative terminals directly to the grid terminals and the midpoint directly to the neutral terminal.The vehicle of claim 1, wherein the bidirectional power factor correction circuit is a bidirectional totem pole power factor correction circuit.The vehicle of claim 1, wherein the isolated DC / DC converter is a three terminal isolated DC / DC converter.The vehicle of claim 3, further comprising an auxiliary battery directly connected to the three-terminal insulated DC / DC converter.The vehicle of claim 4, wherein the three terminal insulated DC / DC converter includes a transformer and a rectifier magnetically coupled to the transformer.The vehicle of claim 4, wherein the isolated three terminal DC / DC converter is configured to selectively transfer power from the auxiliary battery to the traction battery.The vehicle of claim 1, further comprising a controller programmed to, responsive to the grid and neutral terminals being connected to an AC source, disconnect the positive and negative terminals from the grid terminals and disconnect the midpoint from the neutral terminal.A method comprising: after disconnecting grid and neutral terminals associated with a bi-directional power factor correction circuit of a vehicle from an AC source, directly connecting the grid terminals to positive and negative terminals of a traction battery of the vehicle and the neutral terminal to a midpoint of the traction battery such that power flows from the traction battery through the bi-directional power factor correction circuit to an isolated DC / DC converter connected between the bi-directional power factor correction circuit and the traction battery.The method of claim 8, further comprising disconnecting the power terminals from the positive and negative terminals and the neutral from the midpoint such that power from the AC source, when connected to the power and neutral terminals, flows through the bidirectional power factor correction circuit and the isolated DC / DC converter to charge the traction battery.The method of claim 8, further comprising operating the isolated DC / DC converter to transfer power from an auxiliary battery connected to the isolated DC / DC converter to the traction battery.An automotive power system, comprising: a bidirectional power factor correction circuit having grid and neutral terminals configured to be connected to an AC source; a traction battery having positive and negative terminals and a midpoint; an isolated DC / DC converter connected between the bidirectional power factor correction circuit and the traction battery; and a controller programmed to directly connect the positive and negative terminals to the grid terminals and the midpoint to the neutral terminal during a drive mode such that power flows from the traction battery through the bidirectional power factor correction circuit and to the isolated DC / DC converter.The automotive power system of claim 11, wherein the controller is further configured to disconnect the positive and negative terminals from the grid terminals and the midpoint from the neutral terminal during a charging mode such that power from an AC source flows through the bidirectional power factor correction circuit and the isolated DC / DC converter to charge the traction battery.The automotive power system of claim 11, further comprising an auxiliary battery connected to the isolated DC / DC converter.The vehicle of claim 13, wherein the controller is further programmed to operate the isolated DC / DC converter to transfer power from the auxiliary battery to the traction battery.The automotive power system of claim 11, wherein the bidirectional power factor correction circuit is a bidirectional totem pole power factor correction circuit.

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