ELECTRIFIED VEHICLE ELECTRICAL SYSTEM INCLUDING A LOW-RIPMER SINGLE-PHASE STEP-DOWN CHARGER

Abstract

The present invention relates to an electrical system (1) for power transfer of an electrified vehicle comprising a rotating machine (2), an inverter (3), a battery (4), a power interface (5), a set of switches controlled by a control unit (7), arranged to connect two phases of the rotating machine (2) to the power interface (5) such that a first and a second winding (L1, L2) of the rotating machine (2) and respective switch arms (31, 32) of the inverter (3) constitute a bridgeless PFC AC-DC voltage converter between the output voltage bus (6) and the power interface (5), and to connect the third phase (P3) of the rotating machine (2) to the battery (4) such that the third winding (L3) and the respective switch arm (33) constitute a DC-DC voltage converter between the output voltage bus and the battery. Figure 1.

Description

Title of the invention: ELECTRICAL SYSTEM FOR AN ELECTRIFIED VEHICLE COMPRISING A LOW-RIPBER, SINGLE-PHASE, STEP-DOWN CHARGER

[0001] The field of the invention relates to a bidirectional electrical charging system for a battery of an electrified vehicle.

[0002] Typically, an electrified vehicle includes an on-board charger equipped with power electronics adapted for converting alternating current (AC) to direct current (DC). In this type of device, it is common to implement an AC-DC voltage conversion stage of the bridgeless power factor correction (PFC) type. Such a circuit is designed without the use of a traditional rectifier bridge composed of diodes in order to eliminate conduction losses due to diodes, thereby improving the system's efficiency. This is particularly important in high-power applications, such as chargers for electrified vehicles, where these losses can be significant.

[0003] These chargers are generally heavy and bulky due to the power electronics components, particularly the inductors. To improve their integration and manufacturing cost, manufacturers use the windings of the vehicle's rotating machine as the inductance for the charger function. For example, US-A1-20230011977 describes a dynamically reconfigurable power converter comprising a bridgeless PFC circuit using the rotating machine windings. This device implements a boost converter to charge the battery. This architecture generates a minimum output voltage that cannot be lower than the peak grid voltage. This output voltage may be too high for a traction battery.Furthermore, in PFC architectures, the output voltage ripple results from the power factor correction criterion required to meet the distribution network criteria. However, this ripple is undesirable for a traction battery.

[0004] In summary, a single-stage PFC boost converter circuit does not allow simultaneous satisfaction of the two criteria of AC network quality and voltage and current ripple quality on the DC voltage bus side for traction battery charging.

[0005] There is therefore a need to address the aforementioned problems.

[0006] One objective of the invention is to provide an on-board charger with a reduced manufacturing cost. Another objective is to improve the quality criterion on the network side AC and the voltage and current ripple quality on the high voltage DC bus connected to the battery.

[0007] More specifically, the invention relates to an electric vehicle power transfer system comprising a rotating machine, an inverter, a battery, a power interface intended to be connected to an external single-phase AC voltage source, a set of switches controlled by a control unit, the rotating machine comprising a first, a second and a third phase connected respectively to a first, a second and a third winding, the inverter comprising a switch arm per phase and an output voltage bus, each arm comprising an upper switch and a lower switch connecting each phase to the output voltage bus.

[0008] According to the invention, the switch assembly is arranged so as to connect the first and second phases to the power interface in such a way that the first and second windings of the rotating machine and the respective switch arms of the inverter constitute a PFC AC-DC voltage converter without a bridge between the output voltage bus and the power interface, and to connect the third phase to the battery in such a way that the third winding and the respective switch arm of the inverter constitute a DC-DC voltage converter between the output voltage bus and the battery.

[0009] The system according to the invention may include the following additional features, alone or in combination:

[0010] - The system further comprises an inductor electrically connected between the third winding and the battery.

[0011] - The AC-DC voltage converter is bidirectional, constituting a chopper circuit a booster during the battery charging phase and a step-down chopper circuit during the power transfer phase from the battery to the power interface.

[0012] - The DC-DC voltage converter is bidirectional, constituting a chopper circuit step-down converter during battery charging phase and a step-up voltage chopper circuit during power transfer phase from the battery to the power interface.

[0013] An electrified vehicle is envisaged comprising a system according to any one of the preceding embodiments.

[0014] A method for charging a battery of an electrical system is further provided according to any one of the preceding embodiments, the method being implemented by the control unit and comprising the following steps:

[0015] - the connection of the first and second phases to the power supply interface so that the first and second windings of the rotating machine and the respective switching arms of the inverter constitute a PFC-circuit AC-DC voltage converter without a bridge between the output voltage bus and the interface power supply during battery charging phase via the single-phase AC power interface,

[0016] - the connection of the third phase to the battery in such a way that the third The winding and the respective switching arm of the inverter constitute a DC-DC voltage converter between the output voltage bus and the battery during the battery charging phase.

[0017] According to one variant, the DC-DC voltage converter operates as a step-down voltage chopper circuit during the battery charging phase.

[0018] A method for transferring power from a battery of an electrical system according to any of the preceding embodiments to a power interface is further provided, the method being implemented by the control unit and comprising the following steps:

[0019] - the connection of the third phase to the battery in such a way that the third The winding and the respective switching arm of the inverter constitute a DC-DC voltage converter between the output voltage bus and the battery during the energy transfer phase from the battery to the power interface.

[0020] - the connection of the first and second phases to the power supply interface of in such a way that the first and second windings of the rotating machine and the respective switching arms of the inverter constitute a PFC circuit boost converter without a bridge between the output voltage bus and the power interface in the power transfer phase from the battery to the power interface.

[0021] According to one variant, the DC-DC voltage converter operates as a voltage boost chopper circuit in the power transfer phase from the battery to the power interface.

[0022] A control unit for an electrical system according to the invention is also provided, comprising means specifically configured to implement the aforementioned charging and power transfer methods.

[0023] It is further provided computer program comprising instructions which, when the program is executed by a control unit, lead the latter to implement any one of the embodiments of the said preceding charging and power transfer methods.

[0024] Computer-readable recording medium comprising instructions which, when executed by a computer, cause the computer to implement said preceding charging and power transfer methods.

[0025] The invention reduces the manufacturing cost of the on-board charger function of an electrified vehicle and has the main advantage of eliminating the power electronics required for the integration of a conventional charger. using its dedicated components in exchange for the addition of switch components necessary to perform the electrical reconfiguration of the system. Sharing components between the inverter and the rotating machine also reduces the mass of the charger function. Furthermore, the invention reduces voltage ripple across the battery terminals.

[0026] Other features and advantages of the present invention will become more apparent upon reading the following detailed description, which includes embodiments of the invention given by way of non-limiting examples and illustrated by the accompanying drawings, in which:

[0027] [Fig. 1] schematically represents a first embodiment of the electrical system according to the invention.

[0028] [Fig.2] represents more precisely the function of the PFC circuit voltage converter of the first embodiment of the electrical system according to the invention.

[0029] [Fig.3] represents more precisely the function of the step-down voltage converter of the first embodiment of the electrical system according to the invention.

[0030] [Fig.4] schematically represents a second embodiment of the electrical system according to the invention comprising an additional inductance at the level of the DC-DC converter function.

[0031] The invention applies to electrified vehicles comprising a drivetrain that is at least partially electrified or fully electrified, preferably motor vehicles, but not only such as aircraft, trucks, tractors, bicycles, ships.

[0032] Figure 1 represents a first embodiment of the electrical system 1 of an electrified vehicle according to the invention. The electrical system 1 comprises a polyphase rotating machine 2, an inverter 3, a battery 4, a power interface 5, a set of switches including at least switches Ksi, Ks2, Kn, Kde, Kpl and Kp2 and a control unit 7 configured to control the electrical system 1.

[0033] The electrical system 1 is adapted to allow bidirectional charging of the battery 4 with single-phase alternating current. Bidirectional charging means that power can be transmitted in two directions between the battery 4 and the power interface 5, enabling the control of a charging phase and a power transfer phase to an external system. This type of use is commonly referred to as V2X for "Vehicle-to-Everything," V2G for "Vehicle-to-Grid," or V2L for "Vehicle-to-Load," among others. Thus, the charging function is preferably bidirectional. However, this is not mandatory.

[0034] More specifically, the rotating machine 2 is a three-phase electrical machine and comprises three phases P1, P2 and P3, each comprising at least one first winding L1, a second winding L2 and a third winding L3, respectively. In the charging phase of the battery 4 by an external source connected to the power interface 5 or in the energy transfer phase from the battery 4 to an external system, the first phase P1 is intended to be connected to one terminal of the power interface 5 and the second phase P2 is intended to be connected to the second terminal of the power interface 5, while the third phase P3 is intended to be connected to the positive polarity terminal of the battery 4.

[0035] The rotating machine 2 can be an electric generator or a drive unit for the electrified vehicle. According to the invention, the windings of the rotating machine 2 participate in implementing the vehicle's charging function. The charging function includes a bridgeless PFC AC-DC voltage converter and a DC-DC voltage converter, the circuits of which will be described in more detail in the following figures.

[0036] The inverter 3 is a three-phase switching circuit comprising three switching arms 31, 32, and 33 and an output voltage bus 6. Each arm 31, 32, and 33 has an upper switch and a lower switch connecting each phase P1, P2, and P3 to the output voltage bus. Each of the switches is a semiconductor-type switch that may include one or more semiconductor devices, for example, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), or an IGBT (Insulated-Gate Bipolar Transistor), or any other suitable technology sufficiently robust to withstand the voltages and currents of the rotating machine 2 and the battery 4, and resist transient peaks.

[0037] In addition, the switching control of the switches of each bridge arm of the inverter 3 is implemented by a dedicated computer of the inverter 3 to regulate the voltage across the terminals of the bus 6 and the voltage across the terminals of the battery 4.

[0038] A first control, specific to the first and second bridge arms 31 and 32, is provided for regulating the voltage of the voltage bus 6 for the implementation of the AC-DC converter. A second control, specific to the third bridge arm 33, is provided for regulating the voltage across the battery terminals according to the voltage of the voltage bus 6 for the implementation of the DC-DC voltage converter. In other words, the first and second switching controls differ from each other in that they address two distinct converters.

[0039] Battery 4 is the traction battery of the electrified vehicle. Battery 4 can power and recover energy from the rotating machine 2 when the latter is used as a generator, particularly during regenerative braking of the electrified vehicle. Furthermore, battery 4 can be charged by an external source operating at alternating voltage connected to an electrical distribution network and plugged into The power interface 5, for example, a charging station. The battery 4 comprises electrochemical energy storage elements, at least one electrochemical element, which may be of the Lithium-ion type (lithiumized Nickel Manganese Cobalt Oxide (NMC) or lithium iron phosphate (LFP) may be cited as examples of active materials for the positive electrode), Nickel Cadmium (Ni-Cd), Nickel Metal Hydride (Ni-MH), Sodium-ion, or any other technology suitable for powering an electrified vehicle. The battery 4 is a battery capable of operating at a voltage of 48 volts or more, or is a so-called high-voltage battery, for example, several hundred volts, approximately 350 to 450 volts, 800 to 900 volts, or 1200 volts.

[0040] Furthermore, the power supply interface 5 is intended to be connected to an external source operating at single-phase alternating voltage. The power supply interface 5 is suitable for operation at single-phase or polyphase voltage.

[0041] In the context of the invention, the interface 5 delivers at its two terminals a single-phase alternating voltage during the charging phase of the battery 4.

[0042] The output voltage bus 6 is a high voltage bus operating at a voltage value at least equal to the peak value of the external source voltage.

[0043] Preferably, the switch assembly comprises, at the Phase and Neutral terminals of the power interface 5, switches Ksi and Ks2 arranged to connect and disconnect each terminal of the power interface 5 respectively. Switches Ksi and Ks2 are suitable for withstanding the charging voltages and currents of the battery 4. These switches are not mandatory, but are preferable for safety reasons.

[0044] The switch assembly further includes, at the battery 4 polarity terminals, switches Kpl and Kp2 arranged to connect and disconnect each battery 4 polarity terminal from the output voltage bus 6. When the battery 4 supplies the rotating machine, switches Kpl and Kp2 are configured in the closed state so that the current delivered by the battery supplies the inverter 3.

[0045] Furthermore, the switch assembly includes a switch Kde electrically connecting the positive polarity terminal of the battery 4 directly to the third phase P3 of the rotating machine 2, on the opposite side of the third switch arm 33 facing the winding L3. The switch Kde is designed to be operated in a closed state during the battery charging phase via the power supply interface or during the energy transfer phase from the battery to the power supply interface 5.

[0046] Furthermore, the switch assembly includes switch Kn for connecting and disconnecting the third phase P3 to the phase terminal of the power supply interface 5 and the second phase P2 to the neutral terminal of the power supply interface 5. Switch Kn is designed to be operated in an open state in battery charging phase 4 via the power interface or in the energy transfer phase stored by battery 4 to the power interface 5.

[0047] The switch assembly is controllable by the control unit 7 to configure a first stage implementing the PFC voltage boost converter without bridge between the output voltage bus 6 and the power interface 5 where the battery is disconnected from the output voltage bus 6. Then, the switch assembly is controllable by the control unit 7 to configure a second stage implementing the DC-DC voltage converter between the output voltage bus 6 and the battery 4.

[0048] In other words, when battery 4 is charged by an external power source, switches Kpl and Kp2 are opened so as to disconnect battery 4 from the output voltage bus 6. The power interface 5 is connected to the two switch arms 31 and 32 of the inverter 3 only via phases P1 and P2 of the rotating machine 2, such that the first and second windings L1 and L2 of the rotating machine and the respective switch arms of the inverter constitute the bridgeless PFC AC-DC voltage converter. Furthermore, switch Kde is closed so as to connect the third phase P3 to the battery, such that the third winding L3 and the respective switch arm 33 of the inverter 3 constitute the DC-DC voltage converter between the output voltage bus 6 and battery 4.

[0049] Figure 2 more precisely describes the function of the bridgeless PFC AC-DC converter 8, outlined in dashed lines, when a supply voltage is present at the power interface 5 for power transfer during charging or discharging between the battery 4 and the power interface 5. In this figure, elements identical to those described previously are identified by the same reference numerals. The power interface 5 is connected to the first phase P1 and the second phase P2. Switch Kn is open, and switches Ksi and Ks2 are closed. The battery portion is not shown.

[0050] It is important to note that the output voltage bus 6 is disconnected from the battery 4, which is powered by the DC-DC converter implemented by the second stage, which will be described in [Fig. 3]. In this way, the voltage ripples at the output of the PFC function 8, necessary to meet the distribution network criteria, are not present at the terminals of the battery 4. This improves the voltage and current ripple quality on the side of the battery 4 for its charging.

[0051] When the first voltage conversion stage is active, the electrical system 1 is controlled so as to connect the first and second phases PI and P2 to the power supply interface 5 such that the first and second windings L1 and L2 of the rotating machine 2 and the respective commutator arms 31 and 32 of the inverter 3 are arranged as a bidirectional AC-DC converter with PFC circuit without bridge 8 between the output voltage bus 6 and the power interface 5.

[0052] In addition, the AC-DC converter 8 constitutes a boost chopper circuit during the battery charging phase and a step-down chopper circuit during the power transfer phase from the battery to the power interface.

[0053] Several variations of the AC-DC converter, not described in the figures, are envisaged, for which a person skilled in the art will be able to implement the electrical circuits for the following functions. Another variation is envisaged in which the AC-DC voltage converter constitutes a step-down chopper circuit during the battery charging phase and a step-up circuit during the power transfer phase from the battery to the power interface. A further variation is envisaged in which the AC-DC converter is not bidirectional, allowing only battery charging.

[0054] Figure 3 more precisely describes the function of the DC-DC voltage converter 9, outlined in dashed lines, when a supply voltage is present at the power interface 5 for power transfer during charging or discharging between the battery 4 and the power interface 5. In this figure, elements identical to those described previously are labeled with the same reference numerals. The power interface 5 is connected to the first phase P1 and the second phase P2. Switch Kn is open, and switches Ksi and Ks2 are closed. Switch Kde is closed.

[0055] When the second voltage conversion stage 9 is active, the electrical system 1 is controlled to connect the third phase P3 to the battery 4 so that the third winding L3 and the respective switching arm 33 of the inverter 3 constitute a DC-DC voltage converter between the output voltage bus 6 and the battery 4. The voltage converter 9 has the effect of reducing the voltage ripple at the output of the AC-DC converter, thus improving the charging quality of the battery 4.

[0056] In addition, the DC-DC voltage converter is bidirectional and constitutes a step-down chopper circuit during the charging phase of the battery 4 and a step-up voltage chopper circuit during the power transfer phase from the battery 4 to the power interface 5.

[0057] Several variants of the DC-DC converter 9 are envisaged, not described in the figures, for which those skilled in the art will be able to implement the electrical circuits for the following functions. One variant is envisaged in which the DC-DC voltage converter constitutes a step-up chopper circuit during the battery charging phase and a step-down circuit during the power transfer phase from the battery 4 to the power interface 5. Another variant in which the DC-DC converter 9 is not bidirectional, allowing only battery charging.

[0058] In [Fig. 4], a second embodiment of the electrical system 1 is shown. In this figure, the elements identical to those described previously bear the same reference numerals. This second embodiment differs in that it includes an inductor L4 electrically connected between the third winding L3 of the rotating machine 2 and the battery 4 for implementing the DC-DC function 9. The inductor L4 can be positioned on either side of the switch Kde. In this embodiment, the inductor L4 is connected between the switch Kde and the third phase P3. The function of the inductor L4 is to complement the inductor L3 of the rotating machine in order to adjust the amplitude of the voltage ripple across the battery terminals according to the desired voltage ripple quality and charging current.This inductance is sized according to the desired electrical characteristics and the characteristics of the windings of the rotating machine.

[0059] Finally, the invention provides a method for controlling the electrical system 1 implemented by the control unit 7 whose function is to control the configuration of the electrical links by the system of switches in order to allow the charging of the battery 4 in the charging phase and the transfer of power from the battery 4 to an external system in V2X mode.

[0060] The control unit 7 is equipped with an integrated circuit computer and electronic memories, the computer and memories being configured to execute the charging process and the power transfer process. However, this is not mandatory. Indeed, the computer could be external to the control unit 7, while still being coupled to it. In this latter case, it could itself be arranged as a dedicated computer including, for example, a dedicated program. Consequently, the control unit, according to the invention, can be implemented in the form of software modules, electronic circuits, or hardware, or a combination of electronic circuits and software modules.

[0061] More specifically, with reference to [Fig. 1], the battery charging process 4 comprises the following steps:

[0062] - the connection of the first and second phases PI and P2 to the interface power supply 6 such that the first and second windings L1 and L2 of the rotating machine 2 and the respective switching arms 31 and 32 of the inverter 3 constitute a PFC AC-DC voltage converter without a bridge between the output voltage bus 6 and the power supply interface 5 in the charging phase of the battery 4 by the power supply interface 5 in single-phase alternating voltage,

[0063] - the connection of the third phase P3 to the battery 4 in such a way that the third winding L3 and the respective switch arm 33 of inverter 3 constitute a DC-DC voltage converter between the output voltage bus 6 and the battery 4 in the charging phase of battery 4.

[0064] Furthermore, in this charging configuration, the DC-DC voltage converter operates as a step-down chopper circuit. The DC-DC conversion improves the battery charging quality and, in particular, reduces the voltage ripple at the output of the AC-DC converter.

[0065] Furthermore, the process of transferring power from the battery to an external system comprises the following steps:

[0066] - the connection of the third phase P3 to the battery 4 in such a way that the third Winding L3 and the respective switch arm 33 of inverter 3 constitute a DC-DC voltage converter between the output voltage bus 6 and the battery 4 during the energy transfer phase from battery 4 to the power interface 5,

[0067] - the connection of the first and second phases PI and P2 to the interface power supply 5 such that the first and second windings L1 and L2 of the rotating machine 2 and the respective switch arms 31 and 32 of the inverter 3 constitute a PFC circuit AC-DC voltage converter without a bridge between the output voltage bus 6 and the power supply interface 5 in the power transfer phase from the battery 4 to the power supply interface 5.

[0068] Furthermore, in this configuration, the DC-DC voltage converter operates as a voltage boost chopper circuit in the power transfer phase from the battery to the power interface.

[0069] The control method allows bidirectional power transfer.

[0070] The invention is described above by way of example. It is understood that a person skilled in the art is able to carry out different variant embodiments of the invention by combining, for example, the different features above taken alone or in combination, without departing from the scope of the invention.

Claims

Demands

1. An electrified vehicle power transfer electrical system (1) comprising a rotating machine (2), an inverter (3), a battery (4), a power interface (5) for connection to an external single-phase AC voltage source, a set of switches controlled by a control unit (7), the rotating machine (2) comprising a first, second, and third phase (PI, P2, P3) connected respectively to a first, second, and third winding (L1, L2, L3), the inverter (3) comprising a switch arm (31, 32, 33) per phase and an output voltage bus (6), each arm (31, 32, 33) comprising an upper switch and a lower switch connecting each phase (PI, P2, P3) to the output voltage bus (6), the system being characterized in that the switch assembly is arranged so as: - to connect the first and second phases (PI,P2) to the power supply interface (5) such that the first and second windings (L1, L2) of the rotating machine (2) and the respective commutator arms (31, 32) of the inverter (3) constitute a bridgeless PFC AC-DC voltage converter (8) between the output voltage bus (6) and the power supply interface (5), - to connect the third phase (P3) to the battery (4) such that the third winding (L3) and the respective commutator arm (33) of the inverter (3) constitute a DC-DC voltage converter (9) between the output voltage bus (6) and the battery (4).

2. System according to claim 1 further comprising an inductance (L4) electrically connected between the third winding (L3) and the battery (4).

3. System according to claim 1 or 2 wherein the AC-DC voltage converter (8) is bidirectional constituting a boost chopper circuit in the charging phase of the battery (4) and a step-down chopper circuit in the power transfer phase from the battery (4) to the power interface (6).

4. System according to any one of claims 1 to 3 wherein the DC-DC voltage converter (9) is bidirectional constituting a step-down chopper circuit in the charging phase of the battery (4) and a step-up voltage chopper circuit in the power transfer phase from the battery (4) to the power interface (5).

5. Electrified vehicle comprising a system according to any one of claims 1 to 4.

6. A method for charging a battery (4) of an electrical system (1) according to any one of claims 1 to 4, the method being implemented by the control unit (7) and being characterized in that it comprises the following steps: - connecting the first and second phases (PI, P2) to the power supply interface (6) such that the first and second windings (L1, L2) of the rotating machine (2) and the respective commutator arms (31, 32) of the inverter (3) constitute a bridgeless PFC AC-DC voltage converter (8) between the output voltage bus (6) and the power supply interface (5) in the charging phase of the battery (4) by the power supply interface (5) in single-phase alternating voltage,- the connection of the third phase (P3) to the battery (4) such that the third winding (L3) and the respective switching arm (33) of the inverter (3) constitute a DC-DC voltage converter (9) between the output voltage bus (6) and the battery (4) during the battery charging phase (4).

7. Method according to claim 6 wherein the DC-DC voltage converter (9) operates as a step-down chopper circuit during the charging phase of the battery (4).

8. A method for transferring power from a battery (4) of an electrical system (1) according to any one of claims 1 to 4 to a power interface (5), the method being implemented by the control unit (7) and being characterized in that it comprises the following steps: - connecting the third phase (P3) to the battery (4) such that the third winding (L3) and the respective commutator arm (33) of the inverter (3) constitute a DC-DC voltage converter (9) between the output voltage bus (6) and the battery (4) in the phase of transferring energy from the battery (4) to the power interface (5), - connecting the first and second phases (P1, P2) to the power interface (5) such that the first and second windings (L1, L2) of the rotating machine (2) and the respective commutator arms (31, 32) of the inverter (3) constitute a PFC circuit AC-DC voltage converter without bridge (8) between the output voltage bus (6) and the power interface (5) during power transfer phase from the battery (4) to the power interface (5).

9. Method according to claim 8 wherein the DC-DC voltage converter (9) operates as a voltage boost chopper circuit in the power transfer phase from the battery (4) to the power interface (5).

10. Control unit of an electrical system (1) according to any one of claims 1 to 4 comprising means specifically configured to implement the method according to any one of claims 6 to 9.

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