ELECTRICAL POWER TRANSFER SYSTEM COMPRISING A BI-DIRECTIONAL AC-DC CONVERTER

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) and a set of switches, including an AC-DC voltage converter between an output voltage bus (6) and the power interface (5) consisting of a first and second phase (P1, P2) of the rotating machine and the inverter (3), the system being arranged to electrically connect in series the first and second windings (L1, L2) of the rotating machine (2) between a first terminal of the power interface and a first switch arm (31) and to connect a second switch arm (32) to the second terminal of the power interface, and further includes a DC-DC voltage converter (9) between the output voltage bus (6) and the battery (4). Figure 1.

Description

Title of the invention: ELECTRICAL POWER TRANSFER SYSTEM COMPRISING A BI-DIRECTIONAL AC-DC CONVERTER

[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] Another problem with this type of architecture is that it requires a complex set of switches to implement the coupling configurations of the electric machine and electrical equipment. For automotive manufacturers, these architectures require "open winding motor" type electric machines, where the electric machine is neither delta nor star connected, or require access to the neutral. of the electric machine. This requires manufacturers to design diverse electrical systems to meet the needs of different vehicle ranges.

[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 criteria on the AC network side and the voltage and current ripple quality on the high-voltage DC bus connected to the battery. A further objective is to provide a simplified architecture in which the coupling of the electric machine does not require a diversification of electrical connections for different vehicle ranges.

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

[0008] - an AC-DC voltage converter with PFC circuit without a bridge between the bus of output voltage and the power supply interface consisting of the first and second phases of the rotating machine and a first and second arm of said inverter switch arms, wherein the switch assembly is arranged to electrically connect in series the first and second windings of the rotating machine between a first terminal of the power supply interface and the midpoint of the first switch arm and to connect the midpoint of the second switch arm to the second terminal of the power supply interface,

[0009] - and a DC-DC voltage converter between the output voltage bus and the battery.

[0010] According to one variant, the first, second and third windings of the rotating machines are permanently connected to the Neutral Point of the rotating machine.

[0011] According to one variant, the AC-DC voltage converter is bidirectional, constituting 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.

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

[0013] According to one variant, the DC-DC voltage converter consists of the third arm of said inverter switching arms and an inductor electrically connected between the third arm and the battery.

[0014] According to one variant, the DC-DC voltage converter consists of a fourth arm of switches and an inductor electrically connected between the fourth arm and the battery.

[0015] According to one embodiment, the battery, the inverter and the rotating machine are configured to control a phase of recalibration of the rotating machine rotor prior to a power transfer phase comprising a control of alignment of the electric rotor angle with a predetermined direction of the stator air gap field, said predetermined direction being the field resulting from the first and second phases of the rotating machine connected in series when the power interface is connected to an external single-phase alternating voltage source.

[0016] An electrified vehicle is also planned, comprising a system according to any one of the preceding embodiments.

[0017] The invention further provides a method for controlling an electrical system according to any one of the preceding embodiments allowing a power transfer phase between the battery and the power interface, the method being implemented by the control unit and comprising the following steps:

[0018] - the electrically series connection of the first and second windings of the rotating machine between a first terminal of the power interface and the midpoint of the first switch arm and the electrical connection of the midpoint of the second switch arm to the second terminal of the power interface so as to configure a PFC AC-DC voltage converter without a bridge between the output voltage bus and the power interface,

[0019] - the configuration of a DC-DC voltage converter between the voltage bus of output and battery.

[0020] According to an alternative method, the DC-DC voltage converter configuration includes the electrical connection of the third arm of said inverter switching arms and an inductor between the output bus and the battery.

[0021] According to an alternative method, the DC-DC voltage converter configuration includes the electrical connection of a fourth switch arm and an inductor between the output bus and the battery.

[0022] According to one embodiment, the method further comprises a phase of recalibrating the rotor of the rotating machine prior to the power transfer phase, said recalibration phase comprising a command to align the electrical rotor angle with a predetermined direction of the stator air gap field, said predetermined direction being the field resulting from the first and second phases of the rotating machines connected in series when the power interface is connected to an external single-phase alternating voltage source.

[0023] According to a first alignment mode, the alignment control includes the control of the battery, the inverter and the rotating machine so as to supply direct current only to the two phases of the rotating machine selected for the power transfer phase between the battery and the power interface.

[0024] According to a second alignment mode, the alignment control includes the control of the battery, the inverter and the rotating machine according to an angular control mode.

[0025] A control unit is also provided comprising means specifically configured to implement the control method according to the invention.

[0026] A computer program is also provided comprising instructions which, when the program is executed by a motor control unit, cause the motor to implement any one of the embodiments of the control method according to the invention.

[0027] It is further provided a computer-readable recording medium comprising instructions which, when executed by a computer, lead the latter to implement the control method according to the invention.

[0028] The invention has the advantage of reducing the manufacturing cost of an on-board charger for an electrified vehicle by implementing an electrical system that allows the use of the windings of the electric traction rotating machine for the AC-DC function. Furthermore, the system offers a simplified rotating machine architecture where the neutral point does not require an electrical connection interface.

[0029] 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:

[0030] [Fig-1] schematically represents a first embodiment of the electrical system according to the invention.

[0031] [Fig.2] represents more precisely the configuration of the first embodiment of the electrical system according to the invention for the implementation of the AC-DC converter of the function of the on-board charger.

[0032] [Fig.3] represents more precisely the configuration of the first embodiment of the electrical system according to the invention for the implementation of the DC-DC converter of the function of the on-board charger.

[0033] [Fig.4] schematically represents a second embodiment of the electrical system according to the invention implementing a fourth arm of switches for the DC-DC converter.

[0034] [Fig.5] is a graphical representation of the stator air gap fields of the rotating machine according to the phase pairs connected in series to an external source in alternating voltage.

[0035] [Fig.6] is a logic diagram of the control method according to the invention for implementing the rotor recalibration phase.

[0036] [Fig.7] is a graphical representation of the stator air gap field of the rotating machine and angular ranges of rotor positioning at vehicle standstill determining the alignment control according to the invention.

[0037] [Fig.8] represents two cases of electrical system configuration according to the invention for the implementation of the DC voltage alignment control.

[0038] 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.

[0039] 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, Kdcl, Kpl and Kp2 and a control unit 7 configured to control the electrical system 1.

[0040] 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 of the battery 4 and a power transfer phase from the battery 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.

[0041] 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, one second winding L2, and one third winding L3, respectively. The three windings are permanently electrically interconnected to the Neutral Point PN of the rotating machine. In other words, the rotating machine 2 does not have an electrical connection interface to the Neutral Point. PN connected to the switch assembly. It also does not have an accessible access point for a system external to the rotating machine. This configuration has the advantage of offering a single electrical architecture for the rotating machine 2 for several versions of the electrical system 1. This simplifies the industrial manufacturing process for a range of vehicles and reduces manufacturing costs.

[0042] During the battery charging phase 4 or during the energy transfer phase from the battery 4. To an external system, the first phase P1 and the second phase P2 are electrically arranged to be connected in series to the first terminal of the power interface 5. The switch Ksi is adapted to connect and disconnect the second phase P2 to the first terminal of the power interface 5. The switch Ksi is controlled in a closed state during the charging phase of battery 4 and during the energy transfer phase to an external system. The closed state is also called the conducting state, that is, a state allowing the flow of current.

[0043] Furthermore, during the charging and energy transfer phase, the third phase P3 is designed to be disconnected from the electrical system 1. The switch Kn is open. In this configuration, the rotating machine 2 therefore only has two of its phases carrying the alternating current (50Hz or 60Hz) from the distribution network.

[0044] The rotating machine 2 can be an electric generator or a drive unit for the electrified vehicle. According to the invention, two two-phase windings of the rotating machine 2 participate in implementing the vehicle charging function. The charging function includes a bridgeless PFC AC-DC voltage converter implemented by two of the switching arms, 31 and 32, and a DC-DC voltage converter implemented by the switching arm 33. The circuits will be described in more detail in the following figures.

[0045] The inverter 3 comprises a three-phase switching circuit including three switching arms 31, 32 and 33 and an output voltage bus 6. A switching arm is also called a bridge arm. Each arm 31, 32 and 33 has an upper switch and a lower switch. Each of the switches is a semiconductor-type switch which 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.

[0046] More specifically, the first bridge arm 31 includes the midpoint electrically connected to the first phase PI of the rotating machine 2 permanently.

[0047] During the charging phase of the battery 4 or during the energy transfer phase from the battery 4 to an external system, the second arm 32 has the midpoint electrically connected to the second terminal of the power interface 5. The switch Ks2 electrically connects the second terminal to the midpoint of the second arm of switches 32. The switch Ks2 is controlled in a closed state in this configuration.

[0048] Furthermore, in traction mode, the second arm 32 can be electrically connected to the third phase P3 of the rotating machine 2. The switch Kn is arranged to electrically connect the second arm 32 to the third phase P3 and the third arm 33 to the second phase P2. During both the charging and transfer phases, the switch Kn is controlled in the open state. The open state is also called the non-conducting state, which interrupts the flow of current.

[0049] On the opposite side of the rotating machine 2, each switch arm is electrically connected to the output voltage bus 6. For each arm, the Drain of an upper switch is connected to the positive terminal of the output voltage bus 6, the Source of an upper switch is connected to the midpoint of the bridge arm, the Drain of a lower switch is connected to the midpoint of the bridge arm, and the Source of a lower switch is connected to the negative terminal of the output voltage bus.

[0050] In addition, the switching control of the switches of each bridge arm of the inverter 3 is implemented complementaryly by a dedicated computer of the inverter 3 to regulate the voltage across the bus 6 and the voltage across the battery 4 according to a well-known pulse-width modulation technique.

[0051] 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.

[0052] Battery 4 is the traction battery of the electrified vehicle. Battery 4 can supply 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. Battery 4 comprises electrochemical energy storage elements, at least one of which may be of the lithium-ion type (lithiumized nickel manganese cobalt oxide (NMC) or lithium iron phosphate (LFP) may be cited as examples). Examples of active materials for the positive electrode include Nickel Cadmium (Ni-Cd), Nickel-Metal Hydride (Ni-MH), Sodium-ion, or any other technology suitable for powering an electrified vehicle. 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.

[0053] 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. The first terminal of the power supply interface 5 is connected to the Phase line and the second terminal is connected to the Neutral line of the distribution network.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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 powers the rotating machine, switches Kpl and Kp2 are configured in a closed state so that the current delivered by the battery powers the inverter 3. During the battery 4 charging phase by an external source or power transfer phase, switch KP1 is in an open state, and switch Kp2 is in a closed state.

[0058] Furthermore, the switch assembly includes a switch Kdcl electrically connecting the positive polarity terminal of the battery 4 to the midpoint of the third switch arm 33 between the switch Kn and the midpoint of the third arm 33. The switch Kdcl is intended to be controlled in a closed state during the battery charging phase via the power interface or during the energy stored in the battery transfer phase to the power interface 5.

[0059] The switch assembly is controllable by the control unit 7 to configure a first stage implementing the PFC step-up voltage converter without a bridge between the output voltage bus 6 and the power supply 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.

[0060] Furthermore, the electrical system includes an inductor L4 connected between the midpoint of the third arm 33 and the positive terminal of the battery 4. The inductor L4 is sized to meet the electrical requirements of the DC-DC voltage converter for generating the charging or discharging voltage at the battery terminals. The inductance may have a value equal to or different from the windings L1, L2, and L3 of the rotating machine 2.

[0061] When the battery 4 is charged by an external power source, switch Kp1 is open and switch Kp2 is closed so as to disconnect the positive terminal of 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 the phases PI and P2 of the rotating machine 2 such that the first and second windings L1 and L2 are connected in series between a first terminal of the power interface and the midpoint of the first switch arm and the midpoint of the second switch arm is connected to the second terminal of the power interface 5. The first and second windings and the switch arms 31 and 32 constitute the bridgeless PFC AC-DC voltage converter.

[0062] In addition, the Kdcl switch is closed so as to connect the third switch arm 33 and the inductor L4 to the positive terminal of the battery 4 so as to constitute the DC-DC voltage converter between the output voltage bus 6 and the battery 4.

[0063] Other combinations of connecting the phases of the rotating machine 2 with the power interface 5 are envisaged. Alternatively, the switch assembly can be configured so as to connect phases P2 and P3 in series to the power interface and phase PI is disconnected from system 1. Alternatively, the switch assembly can be configured so as to connect phases PI and P3 of the rotating machine 2 in series to the power interface 5 and phase P2 is disconnected from system 1.

[0064] Fig. 2 more precisely describes the function of the bridgeless PFC AC-DC converter 8 framed in dashed lines when a supply voltage is present at the supply interface 5 for power transfer in charge or discharge between the battery 4 and the supply interface 5. In this figure, the elements identical to those described previously bear the same reference.

[0065] The power supply interface 5 has a first terminal connected to the second phase P2, the first and second windings L1 and L2 are connected in series between the first terminal and the midpoint of the first arm of switches 31 of inverter 3.

[0066] Switch Kn is open and is not shown in [Fig. 2], and switches Ksi and Ks2 are closed. The part corresponding to the battery is not shown.

[0067] 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.

[0068] When the first voltage conversion stage is active, the electrical system 1 is controlled so as to electrically connect in series the first and second phase PI and P2 to the first terminal of the power interface 5 and the midpoint of the second switch arm 32 to the second terminal so that the first and second winding L1 and L2 of the rotating machine 2 and the respective switch arms 31 and 32 of the inverter 3 are arranged in a bidirectional PFC circuit AC-DC converter without bridge 8 between the output voltage bus 6 and the power interface 5.

[0069] 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.

[0070] 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.

[0071] 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, the elements identical to those described previously bear the same reference numerals. Switch Kn is open, and switches Ksi and Ks2 are closed. Switch Kdcl is closed.

[0072] The power supply interface 5 is connected to the first phase PI and the second phase P2. The switch Kn is open and the switches Ksi and Ks2 are closed. The switch Kdcl is closed.

[0073] When the second voltage conversion stage 9 is active, the electrical system 1 is controlled to connect the midpoint of the third arm 33 of the inverter 3 to the fourth inductor L4. The fourth inductor L4 and the third 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 reduces the voltage ripple at the output of the AC-DC converter, thereby improving the charging quality of the battery 4.

[0074] 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.

[0075] 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 is envisaged in which the DC-DC converter 9 is not bidirectional, allowing only battery charging.

[0076] 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 a fourth switch bridge arm 34 and an inductor L5 that is part of the DC-DC voltage converter 10 between the output voltage bus 6 and the battery 4. The inductor L5 is connected to the midpoint of the switch arm 34 and to the positive terminal of the battery 4 via a switch Kdc2. The drain of the upper switch of the switch arm 10 is electrically connected to the positive terminal of the output voltage bus 6. The source of the lower switch is electrically connected to the negative terminal of the battery 4.

[0077] For the first and second embodiments of the electrical system 1, the choice of the additional inductance L4 and L5 is linked to the switching frequency permitted by the switching arms implementing the function of the DC-DC voltage converter, i.e. the third arm 33 for the first embodiment and the fourth arm 34 for the second embodiment.

[0078] The additional switching arm 10 uses two transistors sized to operate at high switching frequencies specifically for the DC-DC converter function. As the inductor L5 is specifically sized Depending on the switching frequency of the switch arm 10, the size of the additional inductor L5 can be reduced compared to the first embodiment. Indeed, in the latter, the limitations of the inverter's switching frequency 3 necessitate increasing the inductor size. The fourth switch arm 34 reduces the system cost because the cost of the larger sizing inductor can exceed the cost of the switches.

[0079] 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.

[0080] Several variants of the DC-DC converter 10, not shown in the figures, are envisaged, 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 chopper circuit during the power transfer phase from the battery 4 to the power interface 5. Another variant is envisaged in which the DC-DC converter 10 is not bidirectional, allowing only battery charging. The switching arm 34 can consist of a transistor and a diode to operate the DC-DC function.

[0081] 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 set of switches in order to allow the transfer of power between the battery 4 and the power interface 5, in the charging phase of the battery 4 and in the power transfer phase from the battery 4 to an external system in V2X mode.

[0082] The control unit 7 is equipped with an integrated circuit computer and electronic memories, the computer and memories being configured to perform 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 a possible dedicated program, for example. 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.

[0083] The method for controlling the electrical system 1 comprises the following steps:

[0084] - the electrically series connection of the first and second windings L1 and L2 of the rotating machine 2 between a first terminal of the power supply interface 5 and the midpoint of the first switch arm 31 and the electrical connection of the midpoint of the second switch arm 32 to the second terminal of the power interface 5 so as to configure a bridgeless PFC AC-DC voltage converter 8 between the output voltage bus 6 and the power interface 5,

[0085] - the configuration of a DC-DC voltage converter 9 between the voltage bus of output 6 and battery 4.

[0086] For the first embodiment of the electrical system 1, illustrated by [Fig.3], the configuration of the DC-DC voltage converter includes the electrical connection of the third arm 33 of said switch arms of the inverter 3 and of the inductor L4 between the output bus 6 and the battery 4.

[0087] For the second embodiment of the electrical system 1, illustrated by [Fig.4], the configuration of the DC-DC voltage converter 10 includes the electrical connection of the fourth switch arm 34 and the inductor L5 between the output bus 6 and the battery 4.

[0088] It is understood that the rotating machine 2 comprises only two of its phases connected in series and carrying a current of frequency 50 Hz or 60 Hz from the distribution network during power transfer. The two phases supplied in series can be phases P1 and P2, phases P2 and P3, or phases P3 and P1. This situation is likely to generate a resulting stator air gap field of a pulsating nature, which can generate torque oscillations at the rotor, the intensity of which depends on the rotor angle at rest. The torque oscillations are maximum when the angle between the rotor field and the stator air gap field is approximately 90°.

[0089] To avoid these torque oscillations, the control method includes a rotor recalibration phase once the vehicle is stationary. Recalibration consists of aligning the rotor field with the stator air gap field or, alternatively, configuring them in opposition. In other words, prior to the charging phase or the V2X type power transfer phase, the rotating machine is controlled by the inverter, which is then powered by battery 4, so that the electrical angle between the two fields is equal to 0° or 180°.

[0090] The electrical rotor angle is determined from the mechanical position and calculated based on the number of pole pairs of the rotating machine. This angle is obtained using a resolver. It can also be obtained using other types of position sensors adapted to determine the electrical rotor angle. Sensorless techniques, well known to those skilled in the art, based on the measurement of electrical parameters and / or motor parameters dependent on the rotor position, can be implemented for the calibration phase.

[0091] The angle of the stator air gap field is the resultant of the fields generated by the phases chosen for energy transfer. Three configurations are possible, each determining a direction of the stator air gap field when the two chosen phases are supplied in series for the power transfer phase between the battery and the power supply interface.

[0092] The rotating machine's computer includes means for determining the electrical rotor angle and the stator angle. The stator angle is a predetermined value stored in the memory of the rotating machine's control unit.

[0093] In [Fig. 5], a graph represents the electric rotor field 0e and the resultant of the stator air gap field 0PiP2 during a vehicle standstill situation and when the two phases PI and P2 of the rotating machine are supplied in series by an alternating current from the distribution network. 0e = 0° is indicated for reference.

[0094] To obtain zero oscillation torque, the rotor field 0e must be aligned with the direction of the stator air gap field 0PiP2, or they must be in opposition. To this end, the realignment phase has the function of aligning or in opposition the electric rotor angle 0e with the angle of the stator air gap field 0PiP2 and -0PiP2 for the positions of 330° and 150° respectively.

[0095] 0P i, 0P 2 and 0P 3 are the field directions of each winding of each phase PI, P2 and P3 respectively when a current flows through the windings.

[0096] 0PiP3 and -0PiP3, represented by dashed lines, for positions of 30° and 210° respectively, are the directions of the stator air gap field when phases P1 and P3 are supplied in series. 0P2P3 and -0P2P3, represented by dashed lines, for positions of 90° and 270° respectively, are the directions of the stator air gap field when phases P2 and P3 are supplied in series.

[0097] Figure 6 is a logic diagram representing the rotor calibration phase to avoid torque oscillations. In this example, phases P1 and P2 are electrically powered. The stator field angle corresponds to the direction 0P1P2 and -0P1P2 for positions 330° and 150° respectively.

[0098] More specifically, the rotor realignment phase includes, after a vehicle stop and shutdown (the "Key off" event E0), a step El of determining the position of the rotating machine's electrical rotor angle and verifying said position with respect to the direction of the stator air gap field 0PiP2. The verification includes a step of detecting whether the electrical rotor angle 0e is within an angular range between 0PiP2 - 90° and 0PiP2 + 90°. This verification can be performed over the complementary angular range.

[0099] The purpose of this check is to select the appropriate recalibration command to minimize rotor movement during recalibration.

[0100] In [Fig.7], a graph represents the rotor field and the angular ranges PLA1 and PLA2 determined with respect to the direction of the rotor field to select the recalibration command.

[0101] If the angle 0e is greater than 0PiP2 - 90° and less than 0PiP2 + 90°, in other words, within the range PLA1, referenced by the double-dash arc, then the process selects an alignment step E2, during which the winding of the rotating machine 2 is energized to position the rotor in alignment with the angle closest to the direction of the stator air gap field, i.e., in this example, 0PiP2 equal to 330°

[0102] If the angle 0e is less than 0PiP2 - 90° and greater than 0PiP2+ 90°, in other words within the range PLA2, then the process selects an alignment step E3, during which the winding of the rotating machine 2 is energized to position the rotor in alignment with the angle closest to the direction of the stator air gap field, that is, in this example, -0PiP2 equal to 150°.

[0103] The recalibration command can be operated in two modes.

[0104] In a first alignment mode, the current generated in the stator windings is direct current and controlled by a servo system to a maximum value so as not to exceed the limits of the inverter and the motor. The battery, the inverter, and the rotating machine are controlled so as to supply direct current only to the two phases of the rotating machine selected for the intended power transfer phase between the battery and the power supply interface. The rotor aligns itself naturally with the generated stator field.

[0105] The inverter switch arms 3, associated with the two phases P1 and P2, are controlled to deliver a DC voltage to the windings of the two phases according to the detected angular range, depending on the position of the rotor angle, i.e., whether it is within the PLA1 or PLA2 range. The switch control is configured to apply a DC voltage whose sign aligns the electrical rotor angle with the stator air gap angle, minimizing rotor displacement. The switch control of the two bridge arms is pulse-width modulation (PWM) to function as a DC-DC converter.

[0106] Figure 8 shows the configuration of the second embodiment of the electrical system 1, and in particular the configuration of the battery, inverter, and electric machine for operating the first alignment mode. In this figure, elements identical to those described previously are identified by the same reference numerals.

[0107] This figure shows the circuits corresponding to the two control cases for generating a positive or negative DC voltage across the two windings of the two phases PI and P2 connected in series, for both cases depending on whether the rotor angle belongs to the range PLA1 or PLA2. The switch Kde is open, the switches Kpl and Kp2 are closed, and the switch Kn is closed. The transistors T1, T2, T3, T4, T5, and T6, as well as their respective control circuits, are illustrated in graphs associated with each case.

[0108] The upper circuit corresponds to the case of controlling a positive voltage across phases PI and P2 when the rotor angle belongs to PLA1. The associated graph represents an example of PWM control of transistors T4 and T5 and the freewheeling diodes of transistors T3 and T6. The duty cycle of transistors T4 and T5 is greater than 0.5.

[0109] The lower circuit corresponds to the case of controlling a negative voltage across phases PI and P2 when the rotor angle belongs to PLA2. The associated graph represents an example of PWM control of transistors T3 and T6 and the freewheeling diodes of transistors T4 and T5. The duty cycle of transistors T3 and T6 is greater than 0.5.

[0110] In a second mode, the rotating machine's control unit, driven by torque or speed, provides angular control to bring the rotor to the desired position, preferably the position minimizing rotor displacement. The motor control, for example, a vector control in the Park reference frame, of a type known to those skilled in the art, further includes an angular control that drives the torque or speed control. The desired position is a predetermined value stored in the rotating machine's control unit memory, dependent on the selected phases, for example P1 and P2, for the next power transfer phase between the battery and the power supply interface.

[0111] The method then includes a verification step E4 or E5 of the attainment of the alignment position with the direction of the stator field, 0Pip2 or -0pip2, resulting from the configuration where the two phases PI and P2 of the rotating machine are connected in series to the power supply interface and supplied by a single-phase voltage source of frequency 50Hz or 60Hz.

[0112] When the rotor position reaches the desired stator direction, then the process stops the recalibration command at step E6.

[0113] The recalibration is carried out identically for power transfer configurations where the P2-P3 or P3-P1 phases would be supplied, with the difference that the recalibration would be carried out according to the direction of the resulting stator air gap field for these phases.

[0114] 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, and a set of switches (Ksi, Ks2, Kn, Kdcl, Kpl, Kp2) 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,The system is characterized in that it comprises: - a bridgeless PFC AC-DC voltage converter (8) between the output voltage bus (6) and the power interface (5) consisting of the first and second phases (PI, P2) of the rotating machine and a first and second arm of said switching arms (31, 32) of the inverter, wherein the set of switches is arranged to electrically connect in series the first and second windings (L1, L2) of the rotating machine (2) between a first terminal of the power interface and the midpoint of the first switching arm (31) and to connect the midpoint of the second switching arm (32) to the second terminal of the power interface (5), - and a DC-DC voltage converter (9) between the output voltage bus (6) and the battery (4).

2. Electrical system (1) according to claim 1 in which the first, second and third windings (L1, L2, L3) of the rotating machine (2) are electrically connected to the Neutral Point of the rotating machine (2) permanently.

3. Electrical system (1) 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 (5).

4. Electrical system (1) 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. Electrical system (1) according to any one of claims 1 to 4 wherein the DC-DC voltage converter (9) is constituted by a fourth arm of switches (34) and an inductor (L5) electrically connected between the fourth arm (34) and the battery (4).

6. Electrical system (1) according to any one of claims 1 to 5 wherein the battery (4), inverter (3) and rotating machine (2) are configured to control a rotor timing phase of the rotating machine prior to a power transfer phase comprising an alignment control (E2; E3) of the electric rotor angle with a predetermined direction of the stator air gap field, said predetermined direction being the field resulting from the first and second phases (PI, P2) of the rotating machine (2) connected in series when the power interface (5) is connected to an external single-phase AC voltage source.

7. Electrified vehicle comprising a system according to any one of claims 1 to 6.

8. A method for controlling an electrical system (1) according to any one of claims 1 to 6 allowing a power transfer phase between the battery (4) and the power interface (5), the method being implemented by the control unit (7) and being characterized in that it comprises the following steps: - the electrically series connection of the first and second windings (L1, L2) of the rotating machine (2) between a first terminal of the power interface (5) and the midpoint of the first switch arm (31) and the electrically connection of the midpoint of the second switch arm (32) to the second terminal of the power interface (5) so as to configure a bridgeless PFC AC-DC voltage converter (8) between the output voltage bus (6) and the power interface (5), - the configuration of a DC-DC voltage converter (9) between the output voltage bus (6) and the battery (4).

9. Method according to claim 8 wherein the configuration of the DC-DC voltage converter (9) includes the electrical connection of a fourth switch arm (34) and an inductor (L5) between the output voltage bus (6) and the battery (4).

10. A method according to any one of claims 8 to 9 further comprising a phase of recalibrating the rotor of the rotating machine (2) prior to the power transfer phase, said recalibration phase comprising an alignment control (E2; E3) of the electrical rotor angle with a predetermined direction of the stator air gap field, said predetermined direction being the field resulting from the first and second phases (PI, P2) of the rotating machine (2) connected in series when the power interface (5) is connected to an external single-phase AC voltage source.

11. A method according to claim 10, wherein the alignment control includes driving the battery (4), the inverter (3) and the rotating machine (2) so as to supply direct current only to the two phases (PI, P2) of the rotating machine (2) selected for the power transfer phase between the battery (4) and the power interface (5).