Bidirectional charging system for motor vehicles

Abstract

A bidirectional charging system for a motor vehicle includes a rechargeable energy storage system (RESS) configured to store a first voltage. The RESS is suitable for use with an off-board power source configured to store a second voltage. The system also includes an electric motor having a plurality of motor windings. The system also includes a power inverter disposed between the RESS and the off-board power source. The system is movable between a forward buck mode, a reverse buck mode, a forward boost mode, and a reverse boost mode for selectively transferring power from one of the RESS and the off-board power source to another of the RESS and the off-board power source in response to the power inverter cycling between at least two of an on state, a RESS disconnected state, and an external disconnected state.

Description

Technical Field

[0001] The present disclosure relates to vehicle electrical systems, and more particularly, to a bidirectional vehicle-to-vehicle charging system for a motor vehicle for selectively charging an on-board rechargeable direct current (DC) battery pack or an off-board power source by stepping up or down the voltage. Background Art

[0002] The propulsion system of a pure battery electric vehicle (BEV) typically includes one or more high-voltage multiphase electric machines in the form of motor generator units or traction motors. These electric machines provide power to or draw power from a rechargeable energy storage system (RESS) through a power inverter. The power inverter includes semiconductor switches that are controlled by pulse width modulation or other switching control signals to convert the battery output voltage into an alternating current (AC) output voltage. The AC output voltage of the power inverter module is ultimately transmitted to the individual phase windings of the electric machine. The electric machine is energized to provide power to the vehicle's drivetrain. The energized electric machine can adjust the torque of each gear set of the transmission to achieve optimal system efficiency.

[0003] The BEV also includes a separate DC / DC buck converter to step down the voltage of the battery pack to support lower voltage auxiliary loads. In addition, because the rated voltage of the battery pack of a modern BEV may be higher than the voltage available at a traditional DC charging station, the vehicle may also include a separate DC / DC boost converter to step up the voltage of the off-board power source that charges the battery pack. Buck and boost converters add cost, mass, and volume to the vehicle.

[0004] Therefore, while existing vehicle electrical systems include DC / DC boost converters and DC / DC buck converters to achieve their intended purposes, a new and improved vehicle charging system is still needed to address these issues. Summary of the invention

[0005] According to several aspects of the present disclosure, a bidirectional charging system for a motor vehicle includes a rechargeable energy storage system (RESS) configured to store a first voltage, and the RESS is suitable for use with an off-board power supply configured to store a second voltage. The system also includes an electric motor having a plurality of motor windings. The system also includes a power inverter disposed between the RESS and the off-board power supply. The power inverter is movable to an ON state, in which the power inverter connects the RESS and the off-board power supply to at least one of the motor windings. The power inverter is also movable to an RESS disconnection (OFF) state, in which the power inverter disconnects the connection between the RESS and each motor winding and connects the off-board power supply to at least one of the motor windings. The power inverter is also movable to an external disconnection state, in which the power inverter connects the RESS to at least one of the motor windings and disconnects the off-board power supply from each motor winding. The system is movable between a forward buck mode, a reverse buck mode, a forward boost mode, and a reverse boost mode for selectively transferring power from one of the RESS and the off-board power source to another of the RESS and the off-board power source in response to the power inverter cycling between at least two of an on-state, a RESS disconnected state, and an external disconnected state.

[0006] In one aspect, a power inverter includes a plurality of phase bridge arms, wherein each phase bridge arm is connected to a corresponding motor winding of an electric motor. Each of the phase bridge arms includes a first semiconductor switch and a second semiconductor switch that can be moved between an open position and a closed position. The power inverter also includes an inter-bridge arm switch that is separate from the first semiconductor switch and the second semiconductor switch and is disposed between two phase bridge arms. When the inter-bridge arm switch is moved to the open position, the inter-bridge arm switch can be moved between the open position and the closed position to isolate the phase bridge arms from each other.

[0007] In another aspect, the phase bridge arm includes a first phase bridge arm and a second phase bridge arm. The first phase bridge arm includes a positive terminal connected to a positive terminal of the RESS, and the second phase bridge arm includes a positive terminal connected to a positive terminal of an off-board power source.

[0008] In another aspect, the system is in a forward buck mode in which the power inverter cycles between an on state and an RESS off state to reduce a first voltage of the RESS to a second voltage for charging an off-board power source. The system is in the forward buck mode in response to: the inter-leg switch being moved to an open position; the first semiconductor switch and the second semiconductor switch of the first phase leg being pulse width modulated; the first semiconductor switch of the second phase leg being moved to a closed position; and the second semiconductor switch of the second phase leg being moved to an open position.

[0009] In another aspect, the system is in a reverse buck mode in which the power inverter cycles between an on state and an external off state to step down a second voltage of the off-board power source to a first voltage for charging the RESS. The system is in the reverse buck mode in response to: the inter-leg switch being moved to an open position; the first semiconductor switch and the second semiconductor switch of the second phase leg being pulse width modulated; the first semiconductor switch of the first phase leg being moved to a closed position; and the second semiconductor switch of the first phase leg being moved to an open position.

[0010] In another aspect, the system is in a forward boost mode in which the power inverter cycles between an RESS off state and an on state to boost a second voltage of the off-board power source to a first voltage for charging the RESS. The system is in the forward boost mode in response to: the inter-leg switch being moved to an open position; the first semiconductor switch of the second phase leg being moved to a closed position; the first semiconductor switch and the second semiconductor switch of the first phase leg being pulse width modulated; and the second semiconductor switch of the second phase leg being moved to an open position.

[0011] In another aspect, the system is in a reverse boost mode in which the power inverter cycles between an external disconnect state and an on state to boost a first voltage of the RESS to a second voltage for charging an off-board power source. The system is in a reverse boost mode in response to: an inter-leg switch being moved to an open position; a first semiconductor switch of a first phase leg being moved to a closed position; a first semiconductor switch and a second semiconductor switch of a second phase leg being pulse width modulated; and a second semiconductor switch of the first phase leg being moved to an open position.

[0012] In another aspect, the system further includes an external switch disposed between the power inverter and the off-board power source. The external switch is movable between a closed position, in which the off-board power source is connected to the power inverter, and an open position, in which the off-board power source is disconnected from the power inverter. The system further includes an inductor connected in series between the plurality of motor windings and the off-board power source, configured to mitigate at least one of current ripple or torque ripple.

[0013] According to several aspects of the present disclosure, a bidirectional charging system for a motor vehicle includes a rechargeable energy storage system (RESS) configured to store a first voltage, and the RESS is suitable for use with an off-board power source configured to store a second voltage. The system also includes an electric motor having a plurality of motor windings. The system also includes a power inverter disposed between the RESS and the off-board power source. The power inverter is movable to an on state, wherein the power inverter connects the RESS and the off-board power source to at least one of the motor windings. The power inverter is also movable to an RESS disconnected state, in which the power inverter disconnects the RESS from each of the motor windings and connects the off-board power source to at least one of the motor windings. The power inverter is also movable to an external disconnected state, in which the power inverter connects the RESS to at least one of the motor windings and disconnects the off-board power source from each of the motor windings. The system also includes a controller connected to the power inverter and configured to generate a plurality of control signals. In response to the power inverter receiving a control signal from the controller, the power inverter cycles between at least two of an on-state, a RESS disconnected state, and an external disconnected state. The system can move between a forward buck mode, a reverse buck mode, a forward boost mode, and a reverse boost mode for selectively transferring power from one of the RESS and the off-board power source to another of the RESS and the off-board power source in response to the power inverter cycling between at least two of the on-state, the RESS disconnected state, and the external disconnected state.

[0014] In one aspect, the power inverter includes an inverter controller for generating a plurality of switching signals in response to the inverter controller receiving a control signal from the controller. The power inverter also includes a first phase bridge arm and a second phase bridge arm, wherein each of the first phase bridge arm and the second phase bridge arm is connected to a corresponding motor winding of the motor. Each of the first phase bridge arm and the second phase bridge arm includes a first semiconductor switch and a second semiconductor switch movable between an open position and a closed position in response to the first semiconductor switch and the second semiconductor switch receiving a switching signal from the inverter controller. The power inverter also includes an inter-bridge arm switch separated from the first semiconductor switch and the second semiconductor switch and arranged between the first phase bridge arm and the second phase bridge arm. The inter-bridge arm switch is movable between an open position and a closed position to isolate the first phase bridge arm and the second phase bridge arm from each other when the inter-bridge arm switch is moved to the open position. The first phase bridge arm includes a positive terminal connected to a positive terminal of the RESS, and the second phase bridge arm includes a positive terminal connected to a positive terminal of an off-board power supply.

[0015] In another aspect, the system is in a forward buck mode in which the power inverter cycles between an on state and an RESS off state to reduce a first voltage of the RESS to a second voltage for charging an off-board power source. The system is in the forward buck mode in response to: the inter-leg switch being moved to an open position; the first semiconductor switch and the second semiconductor switch of the first phase leg being pulse width modulated; the first semiconductor switch of the second phase leg being moved to a closed position; and the second semiconductor switch of the second phase leg being moved to an open position.

[0016] In another aspect, the system is in a reverse buck mode in which the power inverter cycles between an on state and an external off state to step down a second voltage of the off-board power source to a first voltage for charging the RESS. The system is in the reverse buck mode in response to: the inter-leg switch being moved to an open position; the first semiconductor switch and the second semiconductor switch of the second phase leg being pulse width modulated; the first semiconductor switch of the first phase leg being moved to a closed position; and the second semiconductor switch of the first phase leg being moved to an open position.

[0017] In another aspect, the system is set in a forward boost mode in which the power inverter cycles between the RESS disconnected state and the on state to boost the second voltage of the off-board power source to a first voltage for charging the RESS. The system is in a reverse buck mode in response to: the inter-leg switch being moved to an open position; the first semiconductor switch of the second phase leg being moved to a closed position; the first semiconductor switch and the second semiconductor switch of the first phase leg being pulse width modulated; and the second semiconductor switch of the second phase leg being moved to an open position.

[0018] In another aspect, the system is in a reverse boost mode in which the power inverter cycles between an external disconnect state and an on state to boost a first voltage of the RESS to a second voltage for charging an off-board power source. The system is in a reverse buck mode in response to: the inter-leg switch being moved to an open position; the first semiconductor switch of the first phase leg being moved to a closed position; the first semiconductor switch and the second semiconductor switch of the second phase leg being pulse width modulated; and the second semiconductor switch of the first phase leg being moved to an open position.

[0019] According to several aspects of the present disclosure, a method for operating a bidirectional charging system for a motor vehicle is provided. The system includes a rechargeable energy storage system (RESS) for storing a first voltage and suitable for use with an off-board power supply for storing a second voltage. The system also includes an electric motor having a plurality of motor windings. The system also includes a power inverter having a first phase bridge arm and a second phase bridge arm, wherein each of the first phase bridge arm and the second phase bridge arm has a first semiconductor switch and a second semiconductor switch. The system also includes a controller and an inter-bridge arm switch arranged between the first phase bridge arm and the second phase bridge arm. The method includes: determining by a controller that a selection of a forward buck mode, a reverse boost mode, a forward boost mode, or a reverse buck mode has been received. The controller generates a plurality of control signals in response to the selection of the forward buck mode, the reverse boost mode, the forward boost mode, or the reverse buck mode. The inverter controller generates a plurality of switch signals in response to the inverter controller receiving a control signal from the controller. In response to the first semiconductor switch and the second semiconductor switch receiving a switching signal from the inverter controller, the first semiconductor switch and the second semiconductor switch cause the power inverter to cycle between at least two states of an on state, a RESS disconnected state, and an external disconnected state. In the on state, the power inverter connects the RESS and the off-board power supply to at least one of the motor windings. In the RESS disconnected state, the power inverter disconnects the connection between the RESS and each motor winding and connects the off-board power supply to at least one of the motor windings. In the external disconnected state, the power inverter connects the RESS to at least one of the motor windings and disconnects the connection between the off-board power supply and each motor winding. The inter-arm switch moves to an open position in response to the inter-arm switch receiving one of the switching signals from the inverter controller. The system is movable between a forward buck mode, a reverse buck mode, a forward boost mode, and a reverse boost mode for selectively transmitting one of a boosted voltage and a reduced voltage from one of the RESS and the off-board power source to the other of the RESS and the off-board power source in response to the power inverter cycling between at least two of an on state, a RESS disconnected state, and an external disconnected state.

[0020] In one aspect, the controller determines to select a forward buck mode, wherein a first voltage of the RESS is higher than a second voltage of the off-board power source. The power inverter cycles between an on-state and an off-state of the RESS, so that current flows through at least one of the motor windings to reduce the first voltage of the RESS to a second voltage for charging the off-board power source. Cycling the power inverter between the on-state and the off-state of the RESS includes: an inter-arm switch is moved to an open position; a first semiconductor switch and a second semiconductor switch of a first phase arm are pulse-width modulated, wherein the first phase arm includes a positive terminal connected to a positive terminal of the RESS, and the second phase arm includes a positive terminal connected to a positive terminal of the off-board power source; a first semiconductor switch of the second phase arm is moved to a closed position; and a second semiconductor switch of the second phase arm is moved to an open position.

[0021] On the other hand, the controller determines to select a reverse buck mode in which a second voltage of the off-board power source is higher than a first voltage of the RESS. The power inverter cycles between an on-state and an external off-state so that current flows through at least one of the motor windings to reduce the second voltage of the off-board power source to a first voltage for charging the RESS. Cycling the power inverter between the on-state and the external off-state includes: the inter-bridge switch is moved to an open position; the first semiconductor switch and the second semiconductor switch of the second phase bridge leg are pulse width modulated; the first semiconductor switch of the first phase bridge leg is moved to a closed position; and the second semiconductor switch of the first phase bridge leg is moved to an open position.

[0022] On the other hand, the controller determines to select a forward boost mode, wherein a first voltage of the RESS is higher than a second voltage of the off-board power source. The power inverter cycles between the RESS disconnected state and the on-state, so that current flows through at least one of the motor windings to boost the second voltage of the off-board power source to a first voltage for charging the RESS. Cycling the power inverter between the RESS disconnected state and the on-state includes: the inter-arm switch is moved to an open position; the first semiconductor switch of the second phase arm is moved to a closed position; the first semiconductor switch and the second semiconductor switch of the first phase arm are subjected to pulse width modulation; and the second semiconductor switch of the second phase arm is moved to an open position.

[0023] On the other hand, the controller determines to select a reverse boost mode in which the second voltage of the off-board power source is higher than the first voltage of the RESS. The power inverter cycles between an external disconnect state and an on state so that current flows through at least one of the motor windings to reduce the first voltage of the RESS to a second voltage for charging the off-board power source. Cycling the power inverter between the external disconnect state and the on state includes: the inter-arm switch is moved to an open position; the first semiconductor switch of the first phase bridge arm is moved to a closed position; the first semiconductor switch and the second semiconductor switch of the second phase bridge arm are subjected to pulse width modulation; and the second semiconductor switch of the first phase bridge arm is moved to an open position.

[0024] In another aspect, the controller receives a software update via over-the-air programming, wherein the software update is associated with a control signal generated by the controller.

[0025] Further areas of applicability will become apparent from the description provided herein.It should be understood that these descriptions and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

[0027] Figure 1 is a perspective view of one example of a motor vehicle having a bidirectional charging system (hereinafter referred to as "system") having a rechargeable energy storage system (RESS) adapted for use with an off-board power source.

[0028] Figure 2 yes Figure 1 A block diagram of a system is shown having a power inverter, an electric motor, and a controller for stepping up or down the voltage transferred between the RESS and an off-board power source.

[0029] Figure 3A yes Figure 2 A circuit schematic diagram of a system of FIG. 1 shows the system in a forward buck mode, wherein the power inverter is set in an on state, in which the power inverter electrically connects the RESS and the off-board power source to the electric motor.

[0030] Figure 3B yes Figure 3A A circuit schematic diagram of a system showing a power inverter in a RESS disconnected state, wherein the power inverter disconnects the electrical connection between the RESS and the motor.

[0031] Figure 4A yes Figure 2A circuit schematic diagram of a system showing the system in a reverse buck mode wherein the power inverter is set in an on state in which the power inverter electrically connects the RESS and the off-board power source to the electric motor.

[0032] Figure 4B yes Figure 4A A circuit schematic diagram of a system showing the power inverter in an external disconnect state, in which the power inverter disconnects the electrical connection between the off-board power supply and the electric motor.

[0033] Figure 5A yes Figure 2 A circuit schematic diagram of a system showing the system in a forward boost mode wherein the power inverter is set in a RESS disconnect state in which the power inverter disconnects the electrical connection between the RESS and the motor and electrically connects the off-board power source to the motor.

[0034] Figure 5B yes Figure 5A A circuit schematic diagram of a system showing the power inverter in an on state, in which the power inverter electrically connects the RESS and the off-board power supply to the electric motor.

[0035] Fig. 6A yes Figure 2 A circuit schematic diagram of a system showing the system in a reverse boost mode wherein the power inverter is set in an external disconnect state in which the power inverter disconnects the electrical connection between the off-board power source and the motor and electrically connects the RESS to the motor.

[0036] Figure 6B yes Fig. 6A A circuit schematic diagram of a system showing the power inverter in an on state, in which the power inverter electrically connects the RESS and the off-board power supply to the electric motor.

[0037] Figure 7 Yes Operation Figure 2 A flow chart of one example of a method of the system is shown. DETAILED DESCRIPTION

[0038] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.

[0039] The present disclosure describes a bidirectional charging system for a motor vehicle, which can obtain a required voltage from one of an on-board rechargeable energy storage system (RESS) and an off-board power source to charge the other of the RESS and the off-board power source by using an on-board rechargeable energy storage system (RESS), a power inverter, and an electric motor without using a dedicated DC / DC converter. As described in detail below, the electric motor includes a motor winding, and the power inverter includes inverter switches, which are driven by a controller to increase or decrease the voltage to charge the RESS or the off-board power source.

[0040] Reference Figure 1 , an example of a bidirectional charging system 10 (hereinafter referred to as the "system") is integrated within a propulsion system of a first motor vehicle 20. The system 10 is a direct current (DC) charging circuit, and the first motor vehicle 20 is depicted as undergoing a DC fast charging operation, wherein the DC charging circuit 10 includes a RESS 115 ( Figure 2 ). The DC charging circuit 10 also includes a charging port 11, which can be electrically connected to an off-board power source 30 via a charging cable 15. In this example, the off-board power source 30 is a RESS of a second motor vehicle 29 and is configured to store a second voltage, as described in more detail below. The charging cable 15 can use a SAE J1772 charging connector, CHAdeMO, or other suitable regional or national standard charging plug or connector.

[0041] The present teachings are independent of the particular charging standard ultimately employed in the system 10, and therefore the examples herein are illustrative only. For consistency of description, the DC charging circuit 10 will be described below as an application of an off-board power source 30 as an integral part of a first motor vehicle 20 and connectable to a second vehicle 29, but the present disclosure is not limited to such an embodiment. It is contemplated that the electrical system may be used as part of any suitable fixed or mobile vehicle, power plant, robot, or platform. For other vehicular applications, the DC charging circuit may also be used as part of an aircraft, ship, rail vehicle, or other suitable vehicle. In other examples, the off-board power source may be a DC fast charging station resident at a certain location.

[0042] The first motor vehicle 20 includes a body 12 and drive wheels 14. The body 12 may define or include a charging port 11 at a location accessible to a user. The first motor vehicle 20 may be implemented in different ways to have a RESS 115 ( Figure 2 ) and a plug-in electric vehicle as described below, for example, a multi-cell lithium-ion battery pack, a zinc-air battery pack, a nickel-metal hydride battery pack, or a lead-acid DC battery pack that can be selectively charged by an off-board power source 30 of a second vehicle 29. Figure 2As best depicted in FIG, the DC charging circuit 10 incorporates the propulsion / traction drive components of a first motor vehicle 20, and its general functions may include providing power to an electric motor 114 (e.g., a traction motor) to generate motor torque and transmit it to the drive wheels 14 for use in propelling the first motor vehicle 20, or for performing other useful work on the first motor vehicle 20.

[0043] Reference Figure 2 The system 100 further includes a first switch 102 disposed between the positive terminal of the off-board power source 30 and the positive terminal of the RESS 115; and a second switch 103 disposed between the negative terminal of the off-board power source 30 and the negative terminal of the RESS 115. When the rated voltages of the off-board power source 30 and the RESS 115 are a common voltage, the first switch 102 and the second switch 103 can be closed, so that one of the off-board power source 30 and the RESS 115 can directly charge the other of the off-board power source 30 and the RESS 115. The first switch 102 and the second switch 103 can be contactors or solid-state relays, which are suitable for closing under an electrical load to ensure that charge is transferred between the off-board power source 30 and the RESS 115 instantaneously or nearly instantaneously. The system 100 also includes a switch S8 disposed between the off-board power source 30 and the power inverter 162 and movable between an open position and a closed position, thereby allowing current to flow through the power inverter 162 and the motor 114 to increase or decrease the voltage when the switch S8 is closed and the power inverter 162 is operated, as will be described in detail below.

[0044] The RESS 115 is configured to store data for use in propelling an electric vehicle, such as the first motor vehicle 20 ( Figure 1 ). In one example, the RESS 115 may be a deep cycle, high ampere capacity battery system rated at about 400 volts to about 800 volts direct current (VDC). In other examples, the RESS voltage rating may be less than 400 volts or greater than 800 volts direct current, depending on, for example, the desired vehicle range, gross vehicle weight, and the power ratings of the various loads drawing power from the RESS 115. Figure 3A-Figure 6B As shown, a DC link capacitor Ci may be connected between the positive terminal and the negative terminal.

[0045] The RESS 115 may include one or more high-voltage, independently rechargeable battery packs that may be electrically connected to one or more multi-phase electric machines, such as a three-phase traction motor 114. More specifically, the RESS 115 may be connected to a high-voltage DC bus and a power inverter 162 for controlling the transfer of electrical energy to and from the electric motor 114.

[0046] like Figure 3A-Figure 6BAs shown, the power inverter 162 is disposed between the RESS 115 and the off-board power source 30. The power inverter 162 can be moved to an on state ( Figure 3A , Figure 4A , Figure 5B and Figure 6B ), wherein the power inverter 162 connects the RESS 115 and the off-board power source 30 to at least one of the motor windings 166. The power inverter 162 can also be moved to the RESS disconnected state ( Figure 3B and Figure 5A ), wherein the power inverter 162 disconnects the connection between the RESS 115 and each motor winding 166 and connects the off-board power source 30 to at least one of the motor windings 166. The power inverter 162 can also be moved to an external disconnect state ( Figure 4B and Fig. 6A ), wherein the power inverter 162 connects the RESS 115 to at least one of the motor windings 166 and disconnects the off-board power source 30 from each of the motor windings.

[0047] The power inverter 162 may be a DC to AC and AC to DC power inverter, which may be part of a traction power inverter module (TPIM). The power inverter 162 is disposed between the RESS 115 and a plurality of motor windings 166 of the motor 114 to transfer electrical energy between the motor 114 and the RESS 115. The motor windings 166 are shown as motor windings La, Lb, and Lc, and may be provided with a three-phase current to generate a rotating magnetic field, thereby rotating a rotor (not shown) of the motor 114. The power inverter 162 may be combined with a plurality of power inverters and correspondingly operable motor control modules to receive motor control commands therefrom and control inverter states to provide motor drive or regeneration functionality.

[0048] The power inverter 162 may include a switch group 164 consisting of semiconductor switches S1-S6 (also referred to herein as "inverter switches"). The power inverter 162 includes a plurality of phase bridge arms, each of which has one or more inverter switches. More specifically, in this example, the power inverter 162 includes a first phase bridge arm P1 having inverter switches S1, S2, a second phase bridge arm P2 having inverter switches S5, S6, and a third phase bridge arm P3 having inverter switches S3, S4. The first phase bridge arm P1 includes a positive terminal connected to a positive terminal of the RESS 115, and the second phase bridge arm includes a positive terminal connected to a positive terminal of an off-board power supply. The inverter switches S1-S6 are movable between an open position and a closed position, and are capable of cooperatively converting the direct current of the RESS 115 into alternating current to power the motor 114 through high-frequency switching in the motor operation mode.

[0049] Each inverter switch S1-S6 can be implemented as a silicon insulated gate bipolar transistor (IGBT), a silicon carbide (SiC) metal oxide semiconductor field effect transistor (MOSFET), a silicon (Si) super junction MOSFET, a gallium nitride (GaN) field effect transistor (FET), a SiC gate junction field effect transistor (JFET), other wide band gap (WBG) or ultra-wide band gap semiconductor power switch devices (UWBG), or other suitable switches with corresponding gates to which gate signals are applied to change the on / off state of a given switch. Each phase of the three-phase traction motor 114 usually has one or more pairs of semiconductor switches. Each phase bridge arm of the power inverter 162 is connected to a corresponding motor phase terminal, such as one of the motor windings 166. The power inverter 162 also includes an inter-bridge arm switch S7 that is separate from the inverter switches S1-S6 and can be moved between an open position and a closed position. The inter-bridge arm switch S7 is arranged between two phase bridge arms to isolate the first phase bridge arm P1 from the other phase bridge arms P2 and P3 when the inter-bridge arm switch S7 is moved to the open position. In another example, the inter-bridge arm switch may be disposed between two phase bridge arms to isolate the two first phase bridge arms P1 , P3 from the other phase bridge arm P2 when the inter-bridge arm switch is movable to an open position.

[0050] The second motor vehicle 29 ( Figure 1 ) may include one or more high-voltage, independently rechargeable battery packs that are electrically connectable to one or more multi-phase electric motors, such as three-phase traction motors (not shown). More specifically, the off-board power supply 30 may be connected to a high-voltage DC bus (not shown) and a power inverter (not shown) to control the transfer of electrical energy to and from the electric motor of the second vehicle 29. Although the off-board power supply may be integrated into a bidirectional charging system similar to system 10, it is contemplated that the off-board power supply may also be integrated into known electrical systems of EVs and HEVs.

[0051] In one example, the first voltage stored by the RESS 115 of the first motor vehicle 20 is higher than the second voltage stored by the off-board power source 30. More specifically, the RESS 115 may be adapted to store approximately 800 volts DC, while the off-board power source may be adapted to store approximately 400 volts DC. It is contemplated that the first voltage of the RESS may be higher or lower than 800 volts DC, while the second voltage of the off-board power source 30 may be higher or lower than 400 volts DC while lower than the first voltage. In another example, the second voltage stored by the off-board power source 30 is higher than the first voltage stored by the RESS 115 of the first motor vehicle 20. The off-board power source 30 may be adapted to store approximately 800 volts DC, while the RESS 115 may be adapted to store approximately 400 volts DC. It is contemplated that the off-board power source may be higher or lower than 800 volts DC, while the RESS may be higher or lower than 400 volts DC while lower than the second voltage of the off-board power source 30.

[0052] The system 10 further includes an external switch S8 disposed between the power inverter 162 and the off-board power source 30, and the external switch S8 is movable between a closed position and an open position, wherein the off-board power source 30 is connected to the power inverter 162 in the closed position, and the off-board power source 30 is disconnected from the power inverter 162 in the open position. The switches S7 and S8 may be contactors adapted to be closed under an electrical load to ensure instantaneous or near instantaneous delivery of power between the phase bridge arms and to the off-board power source 30. Figure 3A-Figure 6B Switches S7 , S8 are shown, and it will be appreciated that in some embodiments, switches S7 , S8 may be replaced with solid state relays.

[0053] The system 10 may further include an inductor L1 connected in series between the plurality of motor windings 166 and the off-board power source 30 , wherein the inductor L1 is configured to mitigate at least one of current ripple or torque ripple.

[0054] The system 10 also includes a controller 150, which may include a processor and a memory for storing computer-readable instructions and having sufficient memory. The memory includes tangible, non-transitory memory, such as read-only memory, whether optical, magnetic, flash memory or other. The controller 150 also includes a sufficient amount of random access memory, electrically erasable programmable read-only memory, etc.; as well as high-speed clocks, analog-to-digital and digital-to-analog circuits, and input / output circuits and devices; and appropriate signal conditioning and buffering circuits. The controller 150 can receive a charge request signal from one or more electronic control units (ECUs) of the first motor vehicle 20. For example, an ECU associated with one or more auxiliary loads (not shown) may provide a signal indicating that the auxiliary load requires power, and the controller 150 may initiate any of a forward buck operation, a reverse boost operation, a forward boost operation, and a reverse buck operation, which will be discussed in more detail below.

[0055] like Figure 3A-Figure 6B As shown, the power inverter 162 also includes an inverter controller 180, which generates switching signals for controlling the operation of semiconductor switches S1-S6 in response to the inverter controller 162 receiving control signals from the controller 150. Similar to the controller 150, the inverter controller 180 may include a processor and a memory for storing computer-readable instructions and having sufficient memory. The memory includes tangible, non-temporary memory, such as read-only memory, whether optical, magnetic, flash memory or other. The inverter controller 180 also includes a sufficient amount of random access memory, electrically erasable programmable read-only memory, etc.; as well as high-speed clocks, analog-to-digital and digital-to-analog circuits, and input / output circuits and devices; and appropriate signal conditioning and buffering circuits.

[0056] In an exemplary embodiment, the inverter controller 180 can receive control signals from the controller 150 and / or from sensors within the motor 114. For example, the motor 114 can include a phase current sensor and / or a rotor position sensor and provide signals indicating the phase current and / or the rotor position, respectively. The inverter controller 180 can control the semiconductor switches S1 to S6 by providing a signal to one or more gates to enable the semiconductor switches S1 to S6 to switch between an open position and a closed position, as will be discussed in more detail below.

[0057] System 10 is in forward buck mode ( Figure 3A-3B ), reverse buck mode ( Figure 4A-4B ), forward boost mode ( Figure 5A-Figure 5B ) and reverse boost mode ( Figure 6A-6BAs described in detail below, in response to the power inverter 162 switching between the on state, the RESS disconnect state, and the external disconnect state, the system 10 switches between these modes to transfer electrical energy from one of the RESS 115 and the off-board power source 30 to the other of the RESS 115 and the off-board power source 30, wherein the switch S7 moves to the open position and the switch S8 moves to the closed position.

[0058] Reference now Figure 3A and Figure 3B , the system 10 is in a forward buck mode, in which the RESS 115 is configured to store a first voltage higher than a second voltage of the off-board power source 30. When the inter-bridge switch S7 moves to an open position; the first semiconductor switch and the second semiconductor switches S1, S2 of the first phase bridge leg P1 are pulse width modulated; the first semiconductor switch S5 of the second phase bridge leg P2 moves to a closed position; the second semiconductor switch S6 of the second phase bridge leg P2 and the first semiconductor switch S3 and the second semiconductor switch S4 of the third phase bridge leg P3 move to an open position; and the external switch S8 moves to a closed position, the power inverter 162 is in an on state ( Figure 3A ) and RESS disconnected state ( Figure 3B ) to reduce the first voltage of the RESS 115 to a second voltage for charging the off-board power source 30. Current flows through one or more motor windings La, Lc to reduce the voltage of the RESS 115 from the first voltage to the second voltage. The inductors La, Lc can reduce the voltage from the first voltage to the second voltage to perform a step-down conversion with the motor winding 166. The inductor L1 can be placed in series with the motor winding 166 to reduce (e.g., mitigate) current pulsation and torque disturbance. In this example, the duty cycle of S1 used for pulse width modulation can be approximately the ratio of the voltage of the off-board power source 30 to the voltage of the RESS 115.

[0059] Reference now Figure 4A and Figure 4B , the system 10 is in a reverse buck mode, in which the off-board power source 30 is configured to store a second voltage higher than the first voltage of the RESS 115. The power inverter 162 is in the on state ( ) when the inter-bridge switch S7 moves to the open position; the first semiconductor switch S5 and the second semiconductor switch S6 of the second phase bridge leg P2 are pulse width modulated; the first semiconductor switch S1 of the first phase bridge leg P1 moves to the closed position; the second semiconductor switch S2 of the first phase bridge leg P1 and the first semiconductor switch S3 and the second semiconductor switch S4 of the third phase bridge leg P3 move to the open position; and the external switch S8 moves to the closed position. Figure 4A ) and external disconnect status ( Figure 4B) to reduce the second voltage of the off-board power source 30 to a first voltage for charging the RESS 115. The current flows through one or more motor windings La, Lc to reduce the voltage of the off-board power source 30 from the second voltage to the first voltage. The inductors La, Lc can reduce the voltage from the first voltage to the second voltage to perform a step-down conversion with the motor winding 166. The inductor L1 can be placed in series with the motor winding 166 to reduce (e.g., mitigate) current pulsation and torque disturbance. In this example, the duty cycle of S5 for pulse width modulation can be approximately the ratio of the voltage of the RESS 115 to the voltage of the external power source 30.

[0060] Reference now Figure 5A and Figure 5B , the system 10 is in a forward boost mode, in which the RESS 115 is configured to store a first voltage higher than a second voltage of the off-board power source 30. The power inverter 162 is in a REFF disconnected state ( REFF disconnected state) when the inter-leg switch S7 moves to an open position; the first semiconductor switch and the second semiconductor switches S1, S2 of the first phase leg P1 are pulse width modulated; the first semiconductor switch S5 of the second phase leg P2 moves to a closed position; the second semiconductor switch S6 of the second phase leg P2 and the first semiconductor switch S3 and the second semiconductor switch S4 of the third phase leg P3 move to an open position; and the external switch S8 moves to a closed position. Figure 5A ) and the on state ( Figure 5B ) to reduce the second voltage of the off-board power source 30 to a first voltage for charging the RESS 115. The current flows through one or more motor windings La, Lc to increase the voltage of the off-board power source 30 from the second voltage to the first voltage. The inductors La, Lc can increase the voltage from the second voltage to the first voltage to perform a step-up conversion with the motor winding 166. The inductor L1 can be placed in series with the motor winding 166 to reduce (e.g., mitigate) current ripple and torque disturbance.

[0061] Reference now Fig. 6A and Figure 6B , the system 10 is in a reverse boost mode, in which the off-board power source 30 is configured to store a second voltage higher than the first voltage of the RESS 115. The power inverter 162 is in an external disconnect state (in the case where the inter-leg switch S7 moves to an open position; the first semiconductor switch S5 and the second semiconductor switch S6 of the second phase leg P2 are pulse width modulated; the first semiconductor switch S2 of the first phase leg P1 moves to a closed position; the second semiconductor switch S2 of the first phase leg P1 and the first semiconductor switch S3 and the second semiconductor switch S4 of the third phase leg P3 move to an open position; and the external switch S8 moves to a closed position. Fig. 6A ) and the on state ( Figure 6B) to increase the first voltage of the RESS 115 to a second voltage for charging the off-board power source 30. The current flows through one or more motor windings La, Lc to increase the voltage of the RESS 115 from the first voltage to the second voltage. The inductors La, Lc can increase the voltage from the first voltage to the second voltage to perform a step-up conversion with the motor winding 166. The inductor L1 can be placed in series with the motor winding 166 to reduce (e.g., mitigate) current ripple and torque disturbance.

[0062] Another example of a power inverter is Figure 3A-Figure 6B The power inverter 162 shown is similar and includes like components labeled with like numbers. Figure 3A-Figure 6B The power inverter 162 shown includes an inter-arm switch S7 directly disposed between the first phase bridge arm P1 and the third phase bridge arm P3, for isolating the first phase bridge arm P1 from the second phase bridge arm P2 and the third phase bridge arm P3 when the inter-arm switch S7 is moved to an open position, but another exemplary power converter may also have an inter-arm switch S7 directly disposed between the third phase bridge arm P3 and the second phase bridge arm P2, for isolating the second phase bridge arm P2 from the first phase bridge arm P1 and the third phase bridge arm P3 when the inter-arm switch S7 is moved to an open position. In yet another example, the power inverter may also include two inter-arm switches, one of which is directly disposed between the first phase bridge arm P1 and the third phase bridge arm P3, and the other switch is directly disposed between the third phase bridge arm P3 and the second phase bridge arm P2. Depending on the selected phase bridge arm connected to the off-vehicle power supply 30, the inter-arm switch is selectively opened to enable the desired operating mode.

[0063] Reference Figure 7 , shows the operation for Figure 2 An example of a method 300 of the system shown. As described in detail below, the controller 150 and / or the inverter controller 180 moves the power inverter 162 to an on state, a RESS disconnected state, and an external disconnected state. In response to the power inverter 162 switching between the on state, the RESS disconnected state, and the external disconnected state, the system 10 switches between a forward buck mode, a reverse buck mode, a forward boost mode, and a reverse boost mode to transfer electrical energy from one of the RESS 115 and the off-board power source 30 to another of the RESS 115 and the off-board power source 30, wherein the switch S7 is in an open position and the switch S8 is in a closed position.

[0064] The method 300 begins at block 302, where the controller 150 determines whether a forward buck mode selection ( Figure 3A and Figure 3B). The controller 150 determines that the forward buck mode is selected, in which the first voltage of the RESS 115 is higher than the second voltage of the off-board power source 30, and the RESS 115 can be used to charge the off-board power source 30. If the controller 150 determines that the forward buck mode selection has been received, the method 300 proceeds to box 304. If the controller 150 determines that the forward buck mode selection has not been received, the method 300 proceeds to box 308.

[0065] At block 304, first, the inter-bridge switch S7 is moved to an open position. The first semiconductor switch S5 of the second phase bridge leg P2 is moved to a closed position. The second semiconductor switch S6 of the second phase bridge leg P2 and the first semiconductor switch S3 and the second semiconductor switch S4 of the third phase bridge leg P3 are moved to an open position. Then, in response to the controller 150 determining that the forward buck mode is selected, the controller 150 generates a plurality of control signals associated with the forward buck mode.

[0066] At block 306, the inverter controller 180 generates a plurality of switching signals in response to the inverter controller 180 receiving the control signal from the controller 150. In response to the first and second semiconductor switches S1-S6 receiving the switching signals from the inverter controller 180, the power inverter 162 cycles between the on state and the RESS off state so that current flows through at least one of the motor windings 166 to reduce the first voltage of the RESS 115 to a second voltage for charging the off-board power source 30. More specifically, cycling the power inverter 162 between the on state and the RESS off state includes subjecting the first and second semiconductor switches S1, S2 of the first phase leg P1 to pulse width modulation, wherein the first phase leg P1 includes a positive terminal connected to the positive terminal of the RESS 115, and the second phase leg P2 includes a positive terminal connected to the positive terminal of the off-board power source 30. In the forward buck mode, the system 10 transmits the reduced voltage from the RESS 115 to the off-board power source 30.

[0067] At block 308, the controller 150 determines whether the reverse buck mode has been selected ( Figure 4A and Figure 4B ), in which the second voltage of the off-board power source 30 is higher than the first voltage of the RESS 115, and the off-board power source 30 can be used to charge the RESS 115. If the controller 150 determines that the selection of the reverse buck mode has been received, the method 300 proceeds to block 314. If the controller 150 determines that the selection of the forward buck mode has not been received, the method 300 proceeds to block 310.

[0068] At block 310, first, the inter-bridge switch S7 is moved to an open position. The first semiconductor switch S1 of the first phase bridge leg P1 is moved to a closed position. The second semiconductor switch S2 of the first phase bridge leg P1 and the first semiconductor switch S3 and the second semiconductor switch S4 of the third phase bridge leg P3 are moved to an open position. Then, in response to the controller 150 determining that the forward buck mode is selected, the controller 150 generates a plurality of control signals associated with the reverse buck mode.

[0069] At block 312, the inverter controller 180 generates a plurality of switching signals in response to the inverter controller 180 receiving the control signal from the controller 150. In response to the first and second semiconductor switches S1-S6 receiving the switching signals from the inverter controller 180, the power inverter 162 cycles between the on state and the external off state so that current flows through at least one of the motor windings 166 to reduce the second voltage of the off-board power source 30 to a first voltage for charging the RESS 115. More specifically, cycling the power inverter 162 between the on state and the external off state includes subjecting the first and second semiconductor switches S5 and S6 of the second phase leg P1 to pulse width modulation, wherein the second phase leg P2 includes a positive terminal connected to a positive terminal of the off-board power source 30. In the reverse buck mode, the system 10 transmits the reduced voltage from the off-board power source 30 to the RESS 115.

[0070] At block 314, the controller 150 determines whether the forward boost mode has been selected ( Figure 5A and 5B ), in which the first voltage of the RESS 115 is higher than the second voltage of the off-board power source 30, and the off-board power source 30 can be used to charge the RESS 115. If the controller 150 determines that the selection of the forward buck mode has been received, the method 300 proceeds to block 316. If the controller 150 determines that the selection of the forward boost mode has not been received, the method 300 proceeds to block 320.

[0071] At block 316 , in response to the controller 150 determining that the forward boost mode is selected, the controller 150 generates a plurality of control signals associated with the forward boost mode.

[0072] At box 318, first, the inter-bridge switch S7 is moved to an open position. The first semiconductor switch S5 of the second phase bridge leg P2 is moved to a closed position. The second semiconductor switch S6 of the second phase bridge leg P2 and the first semiconductor switch S3 and the second semiconductor switch S4 of the third phase bridge leg P3 are moved to an open position. Then, the inverter controller 180 generates a plurality of switching signals in response to the inverter controller 180 receiving a control signal from the controller 150. In response to the first semiconductor switch and the second semiconductor switch S1-S6 receiving the switching signal from the inverter controller 180, the power inverter 162 cycles between the RESS disconnected state and the connected state, so that current flows through at least one of the motor windings 166 to increase the second voltage of the off-board power supply 30 to the first voltage for charging the RESS 115. More specifically, cycling the power inverter 162 between the RESS disconnected state and the connected state includes: subjecting the first semiconductor switch and the second semiconductor switch S1, S2 of the first phase bridge leg P1 to pulse width modulation. In the forward boost mode, the system 10 delivers a boosted voltage from the off-board power source 30 to the RESS 115 .

[0073] At block 320, the controller 150 determines whether the reverse boost mode has been selected ( Fig. 6A and Figure 6B ), in which the second voltage of the off-board power source 30 is higher than the first voltage of the RESS 115, and the RESS 115 can be used to charge the off-board power source 30. If the controller 150 determines that the selection of the reverse boost mode has been received, the method 300 proceeds to block 322. If the controller 150 determines that the selection of the forward buck mode has not been received, the method 300 proceeds to block 302.

[0074] At block 322 , in response to the controller determining that the reverse boost mode is selected, the controller generates a plurality of control signals associated with the reverse boost mode.

[0075] At box 324, the inter-bridge switch S7 is moved to an open position. The first semiconductor switch S1 of the first phase bridge leg P1 is moved to a closed position. The second semiconductor switch S2 of the first phase bridge leg P2 and the first semiconductor switch S3 and the second semiconductor switch S4 of the third phase bridge leg P3 are moved to an open position. Then, the inverter controller 180 generates a plurality of switching signals in response to the inverter controller 180 receiving a control signal from the controller 150. In response to the first semiconductor switch and the second semiconductor switch S1-S6 receiving the switching signal from the inverter controller 180, the power inverter 162 cycles between an external disconnect state and an on state so that current flows through at least one of the motor windings 166 to increase the first voltage of the RESS 115 to a second voltage for charging the off-board power supply 30. More specifically, cycling the power inverter 162 between the external disconnect state and the on state includes subjecting the first semiconductor switch S5 and the second semiconductor switch S6 of the second phase bridge leg P2 to pulse width modulation. In the reverse boost mode, the system 10 transfers the boosted voltage from the RESS 115 to the off-board power source 30 .

[0076] In some embodiments, the software of the controller 150 can be updated based on over-the-air programming. For example, the software update can be transmitted from a data source (e.g., an original equipment manufacturer (OEM)) to the controller 150 via one or more suitable communication networks. The over-the-air update can provide the required parameters for one or more switches S1 to S6 to adjust the charging power by adjusting the converter control signal (e.g., current command, frequency, duty cycle, phase shift, etc.) according to the charging power level via the inverter controller 180.

[0077] The description of the present disclosure is merely exemplary in nature, and variations that do not depart from the gist of the present disclosure fall within the scope of the present disclosure. Such variations should not be regarded as departing from the spirit and scope of the present disclosure.

Claims

1. A bidirectional charging system for a motor vehicle, comprising: a rechargeable energy storage system RESS configured to store a first voltage, and said RESS adapted for use with an off-board power source configured to store a second voltage; an electric motor having a plurality of motor windings; as well as a power inverter disposed between the RESS and the off-board power source, wherein the power inverter: is movable to an on state, in which the power inverter connects the RESS and the off-board power source to at least one of the motor windings; is movable to an RESS off state, in which the power inverter disconnects the connection between the RESS and each of the motor windings and connects the off-board power source to at least one of the motor windings; and is movable to an external off state, in which the power inverter connects the RESS to at least one of the motor windings and disconnects the connection between the off-board power source and each of the motor windings; wherein the power inverter includes an inverter controller that generates a switching signal for controlling operation of a semiconductor switch in response to the inverter controller receiving a control signal from a controller; wherein the system is movable to a forward buck mode, a reverse buck mode, a forward boost mode, and a reverse boost mode to selectively transfer power from one of the RESS and the off-board power source to the other of the RESS and the off-board power source in response to the power inverter cycling between at least two of the on-state, the RESS off-state, and the external off-state; Wherein, the power inverter further includes: a plurality of phase bridge arms, wherein each of the phase bridge arms is connected to a respective one of the motor windings of the electric motor, and each of the phase bridge arms comprises a first semiconductor switch and a second semiconductor switch movable between an open position and a closed position; and An inter-bridge arm switch is separated from the first semiconductor switch and the second semiconductor switch and can be moved between an open position and a closed position, wherein the inter-bridge arm switch is arranged between the two phase bridge arms and is used to isolate the phase bridge arms from each other when the inter-bridge arm switch is moved to the open position.

2. The bidirectional charging system according to claim 1, wherein: The plurality of phase bridge arms include a first phase bridge arm and a second phase bridge arm; The first phase bridge arm includes a positive terminal connected to a positive terminal of the RESS, and the second phase bridge arm includes a positive terminal connected to a positive terminal of the off-vehicle power supply.

3. The bidirectional charging system according to claim 2, wherein: In response to the inter-bridge leg switch being moved to the open position, the first semiconductor switch and the second semiconductor switch of the first phase bridge leg being pulse width modulated, the first semiconductor switch of the second phase bridge leg being moved to the closed position, and the second semiconductor switch of the second phase bridge leg being moved to the open position, the system is in the forward buck mode and the power inverter cycles between the on state and the RESS off state to reduce the first voltage of the RESS to a second voltage for charging the off-vehicle power supply.

4. The bidirectional charging system according to claim 3, wherein: In response to the inter-bridge leg switch being moved to the open position, the first semiconductor switch and the second semiconductor switch of the second phase bridge leg being pulse width modulated, the first semiconductor switch of the first phase bridge leg being moved to the closed position, and the second semiconductor switch of the first phase bridge leg being moved to the open position, the system is in the reverse buck mode and the power inverter cycles between the on state and the external disconnect state to reduce the second voltage of the off-board power supply to a first voltage for charging the RESS.

5. The bidirectional charging system according to claim 4, wherein: In response to the inter-bridge leg switch being moved to the open position, the first semiconductor switch of the second phase bridge leg being moved to the closed position, the first semiconductor switch and the second semiconductor switch of the first phase bridge leg being pulse width modulated, and the second semiconductor switch of the second phase bridge leg being moved to the open position, the system is in the forward boost mode and the power inverter cycles between the RESS disconnected state and the connected state to boost the second voltage of the off-board power supply to a first voltage for charging the RESS.

6. The bidirectional charging system according to claim 5, wherein: In response to the inter-bridge switch being moved to the open position, the first semiconductor switch of the first phase bridge leg being moved to the closed position, the first semiconductor switch and the second semiconductor switch of the second phase bridge leg being pulse width modulated, and the second semiconductor switch of the first phase bridge leg being moved to the open position, the system is in the reverse boost mode and the power inverter cycles between the external disconnect state and the on state to increase the first voltage of the RESS to a second voltage for charging the off-board power supply.

7. The bidirectional charging system according to claim 6, further comprising: an external switch disposed between the power inverter and the off-board power source, and movable between a closed position and an open position, wherein the off-board power source is connected to the power inverter in the closed position, and the off-board power source is disconnected from each of the motor windings in the open position; and An inductor is connected in series between the plurality of motor windings and the off-board power source, wherein the inductor is configured to mitigate at least one of current ripple or torque ripple.

Images