Bidirectional split-phase on-board charger and electrified drivetrain system equipped with it

Abstract

Bidirectional split-phase on-board charger (25) for use with a DC voltage bus (22), wherein the on-board charger (25) has a charging mode and a discharging mode, the on-board charger (25) comprising: a switching block (30) which can be connected to an external vehicle charging station (28) during the charging mode and to an external AC load (140) during the discharging mode; a first DC-AC converter (34); a second DC-AC converter (134), wherein the first DC-AC converter (34) and the second DC-AC converter (134) are connected to the switching block (30);and a DC-DC converter (36) connected to the first DC-AC converter (34), the second DC-AC converter (134), and the DC voltage bus (22), wherein during charging mode the first DC-AC converter (34) and the second DC-AC converter (134) are configured to output an intermediate circuit voltage to the DC-DC converter (36), and the DC-DC converter (36) is configured to output a DC charging voltage or DC charging current to the DC voltage bus (22) when the intermediate circuit voltage reaches a predetermined value, and wherein during discharging mode the first DC-AC converter (34) and the second DC-AC converter (134) are configured to receive a DC discharge voltage or DC discharge current from the DC-DC converter (36) and together, via the switching block (30), selectively output a split-phase AC voltage to supply power to the electrical AC load (140);wherein the electrical AC load (140) includes a single-phase AC device and wherein the on-board charger (25) is configured to output single-phase power to the single-phase AC device via the first DC-AC converter (34) or via the second DC-AC converter (134) during discharge operation.

Description

The present invention relates to a bidirectional split-phase on-board charger and an electrified drive train system equipped therewith. An exemplary bidirectional split-phase on-board charger is described in US 2021 / 0408889 A1. Further state of the art is described in DE 102011075927 A1. INTRODUCTION Electrochemical battery assemblies are used on board battery electrical systems as a primary power supply to provide power to a variety of electrical components. For example, on board an electric vehicle, a traction battery assembly is connected to a high-voltage direct current bus (high-voltage DC bus), with the battery assembly comprising a number of cylindrical, prismatic, or pouch-shaped battery cells appropriate for the application. The DC bus then powers one or more traction electric motors and other high-voltage power electronics components during discharge modes and supplies a charging current to constituent cells of the battery assembly during charging modes. Lower-voltage components, such as a 12-volt lead-acid battery and onboard lighting and sound systems, are connected to a secondary / low-voltage DC bus. Electrified powertrain systems used on board electric vehicles, plug-in hybrid electric vehicles, and other mobile or stationary battery electric systems may be equipped with an onboard charger (OBC) capable of converting an AC charging voltage to a DC charging voltage suitable for charging the aforementioned battery assembly. A typical OBC contains several individual chips of IGBTs, MOSFETs, or other semiconductor switches suitable for the application, each with individually controllable ON / OFF line states. The line states are rapidly controlled, usually via pulse-width modulation along with signal filtering, while the battery assembly remains galvanically isolated. Because existing onboard charging architectures tend to include diode rectification, the resulting power conversion process is unidirectional.However, emerging bidirectional OBC architectures allow for the selective flow of power in the opposite direction, thus enabling a battery assembly to supply power to the grid (vehicle-to-grid or V2G) or to an externally connected electrical load (vehicle-to-load or V2L). Such capability is collectively referred to here and in the general field as vehicle-to-everything (V2X). SUMMARY A split-phase on-board charging module architecture, hereinafter referred to for simplicity as an on-board charger (OBC), is disclosed hereafter, which is operable to selectively output a split-phase voltage to a connected external AC load while retaining the ability to output a single-phase voltage. In particular, the hardware and software solutions described below integrate a split-phase voltage output and a shunt switch assembly (a “switching device”) into the circuit architecture of the OBC to provide improved performance compared to bidirectional single-phase chargers. In contrast to such bidirectional single-phase architectures, the OBC architecture described below uses two DC-AC converters and one DC-DC converter. The two DC-AC converters work together during a charging mode of an on-board battery assembly to provide a total charging power equal to the sum of their respective power outputs. That is, the first DC-AC converter and the second DC-AC converter can each have a power rating approximately half that of a single DC-DC converter, i.e., ideally 50%, or, according to another implementation, within approximately 40% to 50%. During vehicle-to-everything (V2X) operation, these same two DC-AC converters output sinusoidal AC voltage waveforms that are 180° out of phase, i.e., the gap-phase power mentioned above.According to a representative North American implementation of these teachings, the AC voltage capability is 120 V and 240 V, and this non-restrictive exemplary voltage output is used here for illustrative consistency. Nominally, however, the present procedure outputs voltages with a first and a second voltage level, V1 and V2, where the second voltage level, V2, is twice the first voltage level, V1. Thus, single-phase power, as may be required based on the AC electrical power requirement, or split-phase power, if an AC electrical load is energized at both the first and second voltage levels, V1 and V2, can be provided for the AC electrical load at the first voltage level, V1. One aspect of the present invention comprises a bidirectional split-phase OBC for use with a DC voltage bus, wherein the OBC has a charging mode and a discharging mode. The OBC can include a switching block, which can be connected to an external charging station during the charging mode and to an external AC load during the discharging mode, and a first and a second DC-AC converter connected to the switching block. Furthermore, the OBC includes a DC-DC converter connected to the first DC-AC converter, the second DC-AC converter, and the DC bus. During the charging mode, the first and second DC-AC converters are configured to output a DC link voltage to the DC-DC converter, and the DC-DC converter is configured to output a DC charging voltage or DC charging current to the DC bus when the DC link voltage reaches a predetermined value.During discharge mode, the first and second DC-AC converters are configured to receive a DC discharge voltage or current from the DC-DC converter and, together, selectively output a split-phase AC voltage via the switching block to power the electrical AC load. The electrical AC load includes a single-phase AC device, and the OBC is configured to output single-phase power to the single-phase AC device during discharge mode, either via the first or the second DC-AC converter. The switching block can contain three switches, in which case the first DC-AC converter can be connected to the first pair of the three switches, and the second DC-AC converter can be connected to the second pair of the three switches, such that the first DC-AC converter and the second DC-AC converter share one of the three switches. According to one possible design, the three switches are mechanical relays or contactors. An output connector of the OBC can be electrically connected to the switch block and, during the OBC's discharge mode, connected to an external AC electrical load. Such an output connector can include a first voltage terminal, a second voltage terminal, and a neutral terminal. During discharge mode, the first pair of the three switches is connected to the second voltage terminal and the neutral terminal, respectively, and the second pair of the three switches is connected to the neutral terminal and the first voltage terminal, respectively. An input connector of the OBC can include an L1 voltage terminal and an L2 / N voltage terminal. In some configurations, the input connector receives AC power from a Society of Automotive Engineers (SAE) J1772 charging connector. The first and second DC-AC converters can each have a power output that is approximately half the power output of the DC-DC converter. Another aspect of the present invention comprises an electrified powertrain system comprising a DC bus, a power converter with a DC side and an AC side, a battery assembly connected to the DC bus and to the DC side of the power converter, a rotating multiphase electric machine connected to the AC side of the power converter and to a mechanical load, and a bidirectional split-phase OBC connected to the battery assembly. As mentioned above, the OBC has a charging mode and a discharging mode and includes a switching block that can be connected to an external charging station during the charging mode and to an external AC electrical load during the discharging mode.According to this exemplary configuration, the OBC includes a first and a second DC-AC converter connected to the switching block, and a DC-DC converter connected to the first DC-AC converter, the second DC-AC converter, and the DC bus. The first and second DC-AC converters each have a power rating approximately half that of the DC-DC converter. As in the embodiments summarized above, during charging mode, the first and second DC-AC converters are configured to output an intermediate circuit voltage to the DC-DC converter, and the DC-DC converter is configured to output a DC charging voltage or DC charging current to the DC bus when the intermediate circuit voltage reaches a predetermined value.During discharge mode, the first and second DC-AC converters are configured to receive a DC discharge voltage or current from the DC-DC converter and, together, selectively output a split-phase AC voltage via the switching block to power the external AC electrical load. The AC electrical load includes a single-phase AC device, and the OBC is configured to output single-phase power to the single-phase AC device during discharge mode, either via the first DC-AC converter or via the second DC-AC converter. Furthermore, a method for controlling a bidirectional split-phase OBC with a charging mode and a discharging mode is described. One embodiment of the method involves controlling a first DC-AC converter and a second DC-AC converter on a DC bus via an electrical control unit (ECU) to output an intermediate circuit voltage to a DC-DC converter during the charging mode. The first DC-AC converter is connected to a first pair of three switches in a switching block. The second DC-AC converter is connected to a second pair of three switches in the switching block such that the first and second DC-AC converters share one of the three switches. The method includes controlling the DC-DC converter during the charging mode via the ECU to output a DC charging voltage or DC charging current to the DC bus when the intermediate circuit voltage reaches a predetermined value.During the discharge mode, the method according to this embodiment includes providing a DC discharge voltage or DC discharge current from the DC-DC converter to the first DC-AC converter and to the second DC-AC converter, and also controlling the first and second DC-AC converters via the ECU to selectively output a split-phase AC voltage via a switching block to power an external electrical AC load. The above features and advantages, and further features and concomitant advantages of this invention, will readily become apparent from the following detailed description of illustrative examples and embodiments of the present invention when taken together with the accompanying drawings and the attached claims. Furthermore, this invention explicitly includes combinations and partial combinations of the elements and features described above and below. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are integrated into and form part of the patent specification, represent implementations of the invention and, together with the description, serve to illustrate the principles of the invention. Fig. 1 is an exemplary electrified powertrain system equipped with a bidirectional split-phase on-board charger (OBC) configured as shown herein. Fig. 2 is a representative hardware implementation of the OBC shown in Fig. 1. Fig. 3 is a corresponding representative split-phase output waveform of the OBC shown in Fig. 2. Fig. 4 is a side view of a representative motor vehicle equipped with power outlets according to one aspect of the invention. The accompanying drawings are not necessarily to scale and may represent a somewhat simplified depiction of various preferred features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes. Details associated with such features are partly determined by the specific intended application and use environment. DETAILED DESCRIPTION Based on the drawings, in which the same reference numerals throughout the multiple views refer to the same features, Fig. 1 shows an electrified powertrain system 10 with a bidirectional split-phase onboard charger (OBC) 25 constructed according to the present invention. An exemplary embodiment of the OBC 25 is shown in Fig. 2 and is described in further detail with reference to Figs. 2 and 3. The use of the described OBC 25 enables the selective delivery of a split-phase AC voltage output (split-phase AC voltage output) during vehicle-to-load (V2L) operations or vehicle-to-grid (V2G) operations—collectively referred to as vehicle-to-everything (V2X)—while simultaneously retaining the ability to provide a single-phase AC voltage.The solutions presented here are intended to create such capabilities with a corresponding reduction in mass and required packing space, thus enabling integration with the electrified powertrain system 10 from Fig. 1 and with its special carrier system. With regard to such a carrier system, the electrified powertrain system 10 can be used as part of a motor vehicle 11 or another mobile system. As shown, the motor vehicle 11 shown by way of example in Fig. 1 (see also the motor vehicle 11A from Fig. 4) can be equipped as a battery electric vehicle, and the present teachings can also be extended to plug-in hybrid electric vehicles. Alternatively, the electrified powertrain system 10 can be used as part of another mobile system such as a rail vehicle, an aircraft, a watercraft, a robot, agricultural equipment, etc. Likewise, the electrified powertrain system 10 can be stationary, as in the case of a power plant, a hoist, a drive belt, or a conveyor system. Thus, the electrified powertrain system 10 is intended to be used in the representative vehicle configuration from Fig. 1 and Fig. 2.4. Illustrating the teachings presented here. The motor vehicle 11 shown in Fig. 1 comprises a vehicle body 12 and road wheels 14F and 14R, where “F” and “R” denote the front and rear positions, respectively. The road wheels 14F and 14R rotate about respective axes 15 and 150, with the road wheels 14F, the road wheels 14R, or both being supplied with power by an output torque (the arrow TO) from a rotating electric machine (ME) 16 of the electrified powertrain system 10, as indicated by arrow

[14] . Thus, according to this embodiment, the road wheels 14F and 14R represent a mechanical load, although other possible mechanical loads are possible in other carrier systems. For this purpose, the electrified powertrain system 10 comprises a power converter module (PIM) 18 and a high-voltage battery assembly (HVA) 20, e.g.a multi-cell lithium-ion traction battery or a battery with another application-appropriate chemistry, both arranged on a high-voltage DC bus 22. As will be appreciated in the section, the PIM 18 includes a DC side 180 and an AC side 280, the latter being connected to individual phase windings (not shown) of the rotating electric machine 16 when the rotating electric machine 16 is configured, as shown, as a rotating multiphase electric machine in the form of a propulsion or traction motor. As shown, the battery assembly 20 is connected to the DC side 180 of the PIM 18, so that during propulsion modes of the vehicle 11, a battery voltage is supplied from the battery assembly 20 to the PIM 18. The PIM 18, or more precisely a set of semiconductor switches located therein (not shown), is controlled by pulse width modulation, pulse density modulation, or other suitable switching control techniques to convert a DC input voltage on the DC bus 22 into an AC output voltage suitable for powering a high-voltage AC bus 220. Thus, the rapid switching of the resident semiconductor switches of the PIM 18 ultimately supplies current to the rotating electric machine 16, causing the rotating electric machine 16 to generate the output torque (arrow TO) in the range shown in Fig.1 as an embodiment shown, as a motor drive torque to one or more of the road wheels 14F and / or 14R or according to other implementations to another coupled mechanical load. Electrical components of the electrified powertrain system 10 may also include an auxiliary power module (APM) 24 and an auxiliary battery (BAUX) 26. As will be appreciated in the area, the APM 24 is configured as a DC-DC converter connected to the DC bus 22. In operation, the APM 24 is able, through internal switching and voltage transformation, to reduce a voltage level on the DC bus 22 to a lower level suitable for charging the auxiliary battery 26 and / or supplying low-voltage power to one or more accessories (not shown), such as lights, displays, etc. Thus, "high voltage" refers to voltage levels significantly above typical 12-15 volt low-voltage / auxiliary voltage levels, with 400 V or more being an exemplary high-voltage level according to some embodiments of the battery assembly 20. The OBC 25 shown in Fig. 1 can be optionally connected to an external charging station 28 via input / output coupling points (I / O coupling points) 29 during a charging mode in which the battery assembly 20 is recharged by an AC charging voltage (VCH) from the vehicle-external charging station 28. The I / O coupling points 29 can contain one or more output connectors 290A, which are electrically connected to the switching block 30 and can be connected to the external AC electrical load 140 during the discharge mode of the OBC 25. Additionally, the I / O socket 29 can contain one or more input connectors 290B, which are electrically connected to the switching block 30 and can be connected to a charging port 13. For example, a charging cable 28C can be connected to the charging port 13, which is located on the vehicle body 12, e.g., via an SAE J1772 connection. According to such an embodiment, the input connector 290B is configured to receive AC power from a corresponding J1772 charging plug (not shown).As will be appreciated in the field, the electrified powertrain system 10, according to one or more embodiments, can also be configured to selectively receive a DC charging voltage, in which case the OBC 25 is selectively bypassed using a circuit arrangement (not shown) that is otherwise not relevant to the present invention. For the present invention, the OBC 25 operates in different modes: (1) a charging mode, during which the OBC 25 receives the AC charging voltage (VCH) from the vehicle-external charging station 28 to recharge the battery assembly 20, and (2) a discharging mode, represented by arrow V2X, during which the OBC 25 discharges power from the battery assembly 20 to an external AC electrical load (L) 140.In this way, the OBC 25 is bidirectional in its function and, as mentioned above, is able to provide a split-phase output and a single-phase output. Further, as shown in Fig. 1, the electrified powertrain system 10 can also include an electronic control unit (ECU) 50. The ECU 50 is capable of regulating the continuous operation of the electrified powertrain system 10 by transmitting electronic control signals (arrow CCo) to the OBC 25 and, if necessary, possibly to other components or elements of the electrified powertrain 10. The ECU 50 does this in response to electronic input signals (arrow CCI). For the present invention, the electronic input signals (arrow CCI) during the aforementioned charging mode can include communication and / or voltage signals from the vehicle-external charging station 28, which, during V2X operations, etc., request the discharge of power to the external AC electrical load 140.During discharge operation, the electronic input signals (arrow CCI) indicate the specific type of one or more AC devices that form part of the external electrical AC load 140. According to different embodiments, such input signals (arrow CCI) can be actively transmitted or passively detected, enabling the ECU 50 to determine a specific operating mode. In response, the ECU 50 controls the operation of the electrified powertrain system 10, in particular an internal state of the OBC 25, as illustrated below with reference to Fig. 2. For this purpose, the ECU 50 shown in Fig. 1 is equipped with one or more processors (P) 52, e.g., logic circuits, one or more combination logic circuits, one or more application-specific integrated circuits (ASICs), one or more electronic circuits, one or more central processing units, semiconductor IC devices, etc., as well as input / output (I / O) circuits 54, suitable signal conditioning and buffer circuits, and other components such as a fast clock generator to provide the described functionality. Furthermore, the ECU 50 includes an associated computer-readable storage medium, i.e., a memory (M) 56, including read-only, programmable read-only, read / write, a hard disk drive, etc., whether resident, remote, or a combination of both.The processor 52 executes control routines for monitoring relevant inputs from sensing devices and other networked control modules (not shown) and for executing control and diagnostic routines to determine the operation of the OBC 25 and possibly other components of the electrified powertrain system 10. As shown in Fig. 2, the OBC 25, as discussed here, includes the I / O coupling points 29 and an associated switching block 30. Additionally, the OBC 25 includes a first and a second DC-AC converter 34 and 134, respectively, as well as a DC-DC converter 36. The first DC-AC converter 34 and the second DC-AC converter 134 can each have a power rating approximately half that of the DC-DC converter 36 described below. As part of the present procedure, the DC-DC converter 36 operates in two different modes: (1) a voltage mode, during which the OBC 25 ultimately provides the charging voltage for the DC bus 22, and (2) a current mode, during which the OBC 25 provides an electrical current for the DC bus 22.During operating mode (1), the OBC 25 can provide a fixed voltage at its output during restricted situations, such as when the battery assembly 20 is not yet connected or when the battery voltage needs to be tightly regulated at the end of the charging cycle. As will be appreciated in the section, achieving an intermediate circuit voltage (VL) within a specified range is therefore a prerequisite for the operation of the DC-DC converter 36. The representation of the I / O coupling points 29 on an outer surface of a waterproof enclosure 125 allows the OBC 25 to be connected to the external AC electrical load 140 from Fig. 1 for charging operations with external power and during V2X discharge operations. Although these have been omitted from Fig. 2 for clarity and simplicity, those skilled in the art will appreciate that intermediate electrical cables and other connecting hardware would connect to the I / O coupling points 29 and run to the charging port 13 from Fig. 1 for charging and to a power strip 46 for V2X discharge, the power strip 46 being shown in Fig. 4 and described below. In this way, the OBC 25 is bidirectional with respect to its power flow capability, as indicated by the output and input arrows ACO and ACI. According to some embodiments, a ground fault circuit interrupter (GFCI) 32 can be connected between the I / O coupling points 29 and the switching block 30 for further protection against ground faults during a V2X event. As shown, the switching block 30 can contain three switches 31A, 31B, and 31C. According to this embodiment, the first DC-AC converter 34 is connected to a first pair of three switches, i.e., switches 31A and 31B, while the second DC-AC converter 34 is connected to a second pair of three switches, i.e., switches 31B and 31C, so that the first DC-AC converter 34 and the second DC-AC converter 34 share one of the three switches 31A, 31B, and 31C, in this case, switch 31B. Optionally, the three switches 31A, 31B and 31C can be embodied as mechanical relays or contactors, with solid-state switches being an alternative embodiment. As will be appreciated in the section, electrical connections to the charging station 28 can be made via several voltage connection pins or voltage terminals (“wires”), including voltage wires L1 and a wire L2 connected to the neutral conductor (N). For example, an SAE J1772 connector or another suitable connector type can be connected to the charging terminal 13 of Fig. 1 to supply the charging voltage VCH as AC power (the arrow ACI) to the OBC 25 during charging operation. When discharging the battery assembly 20 of Fig. 1 to the external AC electrical load 140 during V2X operations, additional sockets arranged at a convenient location on board the motor vehicle 11 of Fig. 1 or the motor vehicle 11A of Fig. 4 can allow the external AC electrical load 140 to be connected with a suitable gap-phase output voltage level. The DC bus 22 contains a positive and a negative voltage rail, i.e., HVDC+ and HVDC-. For clarity, the first and second DC-AC converters 34 and 134 are labelled with a double-pointed arrow and corresponding AC and DC symbols, i.e., ~ and =, where the double-pointed arrow indicates bidirectional power flow. Similarly, the DC-DC converter 36 is labelled with the bidirectional power flow and the corresponding DC symbol to indicate the DC conversion process. Regarding the operation of the OBC 25, during charging mode, the first DC-AC converter 34 and the second DC-AC converter 134 are configured to output the intermediate circuit voltage (VL) to the DC-DC converter 36. The DC-DC converter 36, in turn, is configured to output a DC charging voltage to the DC bus 22 when the intermediate circuit voltage (VL) reaches a predetermined value, e.g., a variable value based on factors including the current state of charge of the battery assembly 20. During the discharge operating mode, i.e., when the power flow is in the DC-to-AC direction, i.e., from right to left as seen in Fig. 2, the first DC-AC converter 34 and the second DC-AC converter 134 are configured to receive a DC discharge voltage or DC discharge current from the DC-DC converter 36 and together optionally output a gap voltage AC voltage to the switching block 30.Thus, the operation of switches 31A, 31B and 31C provides power for the external electrical AC load 140 from Fig. 1. A representative split-phase output waveform 40 is shown in Fig. 3, in which voltage waveforms 42 and 44 with the same amplitude are phase-shifted by 180° relative to each other. The RMS values ​​of the voltage waveforms 42 and 44 shown, with peaks of 170 V, correspond to an RMS voltage of 120 V VRMS, i.e., such a value is representative and not limited. For simplicity, the RMS subscript is omitted below for the exemplary voltages of 120 V and 240 V. According to such an example, a user can connect a 120 V embodiment of the external AC electrical load 140 from Fig. 1 to a wall outlet representing L1 (or L2) and N, thus providing a single-phase output of 120 V for the external AC electrical load 140.Alternatively, a 240-volt split-phase load could be connected to a plug providing the lines L1, L2 and N to supply 140-240 V (between L1 and L2) and 120 V (between L1 and N or L2 and N) for the external AC electrical load. Using an SAE J1772 charging connector as an example, such a connector brings together the neutral conductor (N) and the voltage line L2, this combination being shown as N / L2 in Fig. 2. Together with the voltage line L1, the SAE J1772 connection thus uses two wires to conduct the power flow during charging of the battery assembly 20 via the vehicle-external charging station 28 from Fig. 1. However, a third wire is necessary when discharging to the external split-phase AC load 140, thus requiring, as shown in Fig. 2, the three-wire connector L1, L2, and N. As shown, the I / O coupling points 29 from Fig. 2 thus allow the connection of the lines L1, L2, N, and N / L2. Using the vehicle 11A from Fig. 4 as an example, existing V2X operations using the OBC 25 are typically performed by plugging an accessory with a socket or a connector strip into the charging port 13 from Fig. 1 to draw AC power from the vehicle. Detection of the connector strip in such an implementation is a prerequisite for initiating V2X power download via the charging port 13. Applying AC voltage to the terminals of the AC charging port 13 could pose a contact hazard if the terminals are accessible. The accessory effectively blocks the conductive terminals of the charging port 13 from this contact hazard. When this accessory is plugged into the charging port 13, the vehicle is disabled.In contrast, the present teachings can be implemented by connecting the power outlet 46 to the motor vehicle 11A at a conveniently accessible location inside and / or outside the motor vehicle 11A. Furthermore, the motor vehicle 11A can be driven while power is being supplied to the power outlet 46. For example, according to various embodiments, the power outlet 46 could be mounted within a front and / or rear storage compartment 17 and / or 19 or within a passenger compartment of the motor vehicle 11A. If the motor vehicle 11A is configured as an electric delivery van, as shown, the front storage compartment 17 can be used as a front trunk (“frunk”) for transporting cargo, with the power outlet 46 possibly mounted therein, perhaps flush with a wall to minimize its protrusion into the volume of the front storage compartment 17. Similarly, the power outlet 46 could be mounted within the rear storage compartment 19, which, according to this example, is an open or closed truck bed, but according to other embodiments, possibly a trunk.In other configurations of the motor vehicle 11A, or if the carrier system is a completely different type of vehicle such as a ship, an aircraft, a train, etc., other possible locations could be used, so that the representative locations from Fig. 4 are only intended to illustrate two possibilities. According to an exemplary implementation, the power outlet 46, with power outlets 48A and 48B at the first and second voltage levels V1 and V2 respectively, and corresponding socket configurations, could be offered to a user as V2X power options when the external AC electrical load 140 shown in Fig. 1 is powered. Optionally, a user could press down a switch (not shown) located outside the OBC 25 to selectively power power outlets 48A and 48B as desired. As an illustrative use case, an oven may have a heating element with a rated voltage of 240 V, an auxiliary power board, and indicator lamps, the latter two features being powered by a rated voltage of 120 V, as will be appreciated in the field.Such a device could be connected to the OBC 25 shown in Fig. 1 by plugging it into the aforementioned power outlet 48A and supplying it with power via the split-phase output described here. Alternatively, one or more of the power outlets 48B could provide a single-phase power outlet from one of the DC-AC converters 34 or 134, for example, to power a radio or lamps. The number and arrangement of the power outlets 48A and 48B could vary depending on the specific application. Although the foregoing invention has been specified with respect to the representative electrified powertrain system 10 from Fig. 1 and the possible carrier systems of the motor vehicles 11 and 11A from Figs. 1 and 4, respectively, those skilled in the art will recognize that the described architecture is suitable for implementing an associated method for controlling the bidirectional split-phase OBC 25 with the aforementioned charging and discharging mode. Such a method can proceed as follows. During the charging mode, the method can include controlling the first DC-AC converter and the second DC-AC converter to output the intermediate circuit voltage (VL) to the DC-DC converter 36 via the ECU 50 from Fig. 1. Additionally, the method can include controlling the DC-DC converter 36 via the ECU 50 to output a DC charging voltage or a DC charging current to the DC bus 22 when the intermediate circuit voltage (VL) reaches a predetermined value.During the discharge mode, the method can include providing a DC discharge voltage or DC discharge current from the DC-DC converter 36 for the first DC-AC converter 34 and for the second DC-AC converter 134, as well as controlling the first and second DC-AC converters 34 and 134 via the ECU 50 to selectively output a gap-phase AC voltage to a switching block 30 from Fig. 2 and thereby supplying power to the external electrical AC load 140. Such a method can include receiving AC power via the input connector 290B of the switch box 30 during charging mode, the input connector 290B having the aforementioned voltage terminal L1 and the combined voltage terminal L2 / N. As also described above, the method can include selectively outputting a single-phase AC voltage via the switch box 30 during discharging mode, thereby supplying power to the external electrical AC load 140 with a single-phase AC signal waveform. In this way, the bidirectional split-phase OBC 25 from Fig. 2 can be used to provide a wider range of power outputs with a corresponding reduction in package size and mass. These and other concomitant advantages are obvious to those skilled in the art from the foregoing invention.

Claims

Bidirectional split-phase on-board charger (25) for use with a DC voltage bus (22), wherein the on-board charger (25) has a charging mode and a discharging mode, the on-board charger (25) comprising: a switching block (30) which can be connected to an external vehicle charging station (28) during the charging mode and to an external AC load (140) during the discharging mode; a first DC-AC converter (34); a second DC-AC converter (134), wherein the first DC-AC converter (34) and the second DC-AC converter (134) are connected to the switching block (30);and a DC-DC converter (36) connected to the first DC-AC converter (34), the second DC-AC converter (134), and the DC voltage bus (22), wherein during charging mode the first DC-AC converter (34) and the second DC-AC converter (134) are configured to output an intermediate circuit voltage to the DC-DC converter (36), and the DC-DC converter (36) is configured to output a DC charging voltage or DC charging current to the DC voltage bus (22) when the intermediate circuit voltage reaches a predetermined value, and wherein during discharging mode the first DC-AC converter (34) and the second DC-AC converter (134) are configured to receive a DC discharge voltage or DC discharge current from the DC-DC converter (36) and together, via the switching block (30), selectively output a split-phase AC voltage to supply power to the electrical AC load (140);wherein the electrical AC load (140) includes a single-phase AC device and wherein the on-board charger (25) is configured to output single-phase power to the single-phase AC device via the first DC-AC converter (34) or via the second DC-AC converter (134) during discharge operation. On-board charger (25) according to claim 1, wherein the switching block (30) comprises three switches (31A, 31B, 31C), wherein the first DC-AC converter (34) is connected to a first pair of the three switches (31A, 31B, 31C) and the second DC-AC converter (134) is connected to a second pair of the three switches (31A, 31B, 31C) such that the first DC-AC converter (34) and the second DC-AC converter (134) share one of the three switches (31A, 31B, 31C). On-board charger (25) according to claim 2, wherein the three switches (31A, 31B, 31C) are mechanical relays or contactors. On-board charger (25) according to claim 2, which further comprises an output connector (290A) which is electrically connected to the switching block (30) and can be connected to the external electrical AC load (140) during the discharge operating mode of the on-board charger (25). On-board charger (25) according to claim 4, wherein the output connector (290A) includes a first voltage terminal, a second voltage terminal and a neutral terminal, and wherein during the discharge mode: the first pair of the three switches (31A, 31B, 31C) is connected to the second voltage terminal and the neutral terminal, respectively; and the second pair of the three switches (31A, 31B, 31C) is connected to the neutral terminal and the first voltage terminal, respectively. On-board charger (25) according to claim 1, which further comprises an input connector (290B) with an L1 voltage connection and with an L2 / N voltage connection. On-board charger (25) according to claim 6, wherein the input connector (290B) is configured to receive AC power from an SAE J1772 charging connector. On-board charger (25) according to claim 1, wherein the first DC-AC converter (34) and the second DC-AC converter (134) each have a power output that is about half the power output of the DC-DC converter (36). Electrified powertrain system (10) comprising: a DC voltage bus (22); a power converter (18) with a DC side and an AC side; a battery assembly (20) connected to the DC voltage bus (22) and to the DC side of the power converter (18); a rotating multiphase electric machine (16) connected to the AC side of the power converter (18) and to a mechanical load; and a bidirectional split-phase on-board charger (25) connected to the battery assembly (20) and having a charging mode and a discharging mode, wherein the on-board charger (25) comprises: a switching block (30) which can be connected to an external vehicle charging station (28) during the charging mode and to an external electrical AC load (140) during the discharging mode; a first DC-AC converter (34); a second DC-AC converter (134),wherein the first DC-AC converter (34) and the second DC-AC converter (134) are connected to the switching block (30); and a DC-DC converter (36) connected to the first DC-AC converter (34), the second DC-AC converter (134), and the DC voltage bus (22), wherein the first DC-AC converter (34) and the second DC-AC converter (134) each have a power rating approximately half the power rating of the DC-DC converter (36), and wherein: during the charging mode, the first DC-AC converter (34) and the second DC-AC converter (134) are configured to output an intermediate circuit voltage to the DC-DC converter (36), and wherein the DC-DC converter (36) is configured to output a DC charging voltage or DC charging current to the DC voltage bus (22) when the intermediate circuit voltage reaches a predetermined value; during the discharging mode, the first DC-AC converter (34) and the second DC-AC converter (134) are configured to are,to receive a DC discharge voltage or DC discharge current from the DC-DC converter (36) and, together via the switching block (30), selectively output a split-phase AC voltage to supply power to the external electrical AC load (140); wherein the electrical AC load (140) includes a single-phase AC device and wherein the on-board charger (25) is configured to output single-phase power to the single-phase AC device during discharge operation via the first DC-AC converter (34) or via the second DC-AC converter (134).

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