Method of charging an electric vehicle with a charging station whose maximum voltage is higher or lower than the maximum voltage of the vehicle's battery

Abstract

Method for charging an electric vehicle with a charging station having a maximum voltage higher or lower than the maximum voltage of a vehicle battery. The invention relates to a method (100) for charging a vehicle comprising: - a battery, - an electric motor comprising windings, - an inverter connected to the windings, - an electrical branch comprising a pre-charge capacitor and a switch, the electrical branch being capable of being connected on the one hand in parallel with a DC charging station and on the other hand to one of the windings and to a negative input terminal of the inverter, the method (100) comprising a connection (104, 114) of the electrical branch to the charging station, and, when the DC charging station is capable of delivering a voltage greater than or equal to the maximum voltage of the battery, the switch being open,The battery is recharged (106) via at least one switching arm of the inverter without switching that arm. (Figure 6)

Description

Title of the invention: Method for charging an electric vehicle with a charging station whose maximum voltage is higher or lower than the maximum voltage of the vehicle's battery

[0001] The present invention relates to the fields of automotive and electrotechnics, and more specifically concerns a charging method for electric or hybrid vehicles.

[0002] Electric or hybrid vehicles have high-voltage batteries of several hundred volts, enabling them to power their electric traction or propulsion motors over long distances. With the evolution of battery technologies and the desire to increase the range of these vehicles, some vehicles now have high-voltage batteries of 800V (volts), while most DC charging stations can only deliver up to 400V.

[0003] However, such an electric or hybrid vehicle whose high-voltage battery can take a voltage greater than, for example, 500V, cannot be fully or partially recharged with a charging station delivering a maximum voltage of 400V, if the vehicle does not have a high-power voltage booster, converting the voltage delivered by the station into a voltage greater than that of the high-voltage battery to be recharged, in order to apply it to the terminals of the latter.

[0004] Such an electric or hybrid vehicle must therefore include a high-power voltage booster and must also be able to directly recharge the high-voltage battery with a charging station delivering a maximum voltage exceeding 800V. The electric vehicle's on-board charging system must therefore be versatile and must not impact the vehicle's traction operation, particularly when this charging system reuses elements of the vehicle's powertrain, such as its inverter.

[0005] Such a charging system generally requires a significant number of switches to reconfigure the electrical connections of the charging system depending on the charging station used and the vehicle's charging or traction mode. It is therefore costly and bulky, especially since these switches are designed to withstand currents of at least one hundred amperes.

[0006] The present invention aims to remedy at least partially the aforementioned drawbacks by providing a method for charging an electric or hybrid vehicle, which minimizes the number of components required in the vehicle for charging, whether this charging uses a charging station with a voltage higher or lower than a maximum voltage of a high-voltage vehicle battery, while meeting performance requirements for this charging and safety requirements.

[0007] To this end, the invention proposes a method for charging an electric or hybrid vehicle, the electric or hybrid vehicle comprising: -a high-voltage battery, - an electric motor comprising stator windings, each having a first and a second end, - an inverter suitable for connection at the input to the high-voltage battery and at the output to the first ends of the stator windings of the electric motor, the inverter comprising at least one switching arm per stator winding, each switching arm comprising an upper switch connected between a midpoint of the switching arm and a positive input terminal of the inverter, and a lower switch connected between a midpoint of the switching arm and a negative input terminal of the inverter, the midpoint being connected to the first end of the stator winding, and - a charging system comprising: - a charging socket suitable for connection to a DC charging station, - an electrical branch suitable for connection, by one of its terminals, to at least the second end of one of the stator windings and to a positive connection of the charging socket, and by a second of its terminals, to a negative input terminal of the inverter and to a negative connection of the charging socket, the electrical branch comprising a series arrangement of a pre-charge capacitor and a switch called a step-up switch, - at least one contactor connected on one side to one of the positive or negative connections of the charging socket and on the other side to the first terminal or respectively to the second terminal of the electrical branch, the charging process comprising a step of connecting the electrical branch by the first of its terminals, to the second end of the stator winding and to the positive connection of the charging socket, and by the second of its terminals, to the negative input terminal of the inverter and to the negative connection of the charging socket, and a step of charging the high-voltage battery by a DC charging terminal, to which the charging socket is connected, The charging method is characterized in that, when the DC charging station is capable of delivering a voltage greater than or equal to the maximum voltage of the high-voltage battery, then during the charging stage, the boost switch is opened, and the charging stage uses at least one switching arm of the inverter, the upper switch of the switching arm being kept closed throughout the charging stage and the lower switch of the switching arm being kept open throughout the charging stage, so that at least part of the current from the charging station passes through the stator winding.

[0008] Thanks to the invention, charging a high-voltage battery using a charging station capable of delivering a voltage greater than or equal to the maximum voltage of the high-voltage battery does not require a direct connection between the positive connection of the charging socket and a positive terminal of the battery. This would necessitate an additional power switch compared to the charging system used in the invention. In fact, in the invention, such charging uses an electrical path between the positive connection of the charging socket and at least one stator winding of the vehicle's electric motor. This electrical path is identical to that used to charge the vehicle with a charging station whose maximum voltage is strictly lower than the maximum voltage of the high-voltage battery.Furthermore, the charging according to the invention by a charging station capable of delivering a voltage greater than or equal to the maximum voltage of the high-voltage battery does not use the inverter and the stator winding in voltage boost mode, which limits the electrical losses of such a charging, as the charging current is not chopped during this charging.

[0009] Finally, with the step-up switch open, a resonance phenomenon is avoided between the pre-charge capacitor and any other capacitor in the charging system, such as a smoothing capacitor connected in parallel at the inverter input and the high-voltage battery output. This step-up switch also allows the second end of the stator winding to be released during vehicle operation, so as not to disrupt the operation of the vehicle's drive system during this phase. Its parallel positioning with the charging socket allows it to be sized to withstand a maximum current of a few tens of amperes, for example, 35 A, compared to a positioning between the positive connection of the charging socket and the second stator winding, for which it would need to be sized to withstand at least one hundred amperes.

[0010] The charging system used by the charging method according to the invention therefore does not include a bypass branch of the powertrain, and is therefore less expensive than charging systems using such a bypass branch.

[0011] Furthermore, it should be noted that in this patent application, unless otherwise stated, an input or output connection of a functional assembly such as the inverter or the voltage booster assembly is understood as a connection to the terminals of that input or output respectively, that is to say, a parallel connection to that input or output respectively. Here, the inverter is specifically connected at its output (with respect to its inverter function) to the first ends of the stator windings of the vehicle's electric motor.

[0012] Furthermore, the term "suitable for connection to" means that at least one current-interrupting device is interposed between the elements suitable for connection together. Specifically, there is at least one current-interrupting device between the electrical branch and one of the electrical points, namely the positive connection of the load socket, the negative connection of the load socket, the negative input terminal of the inverter, and the second end of the stator winding. The electrical branch may be directly connected, without an interruption device, to one or more of these four electrical points. The second end of the stator winding may also correspond to an intermediate terminal of a winding segmented into several coils.Indeed, the purpose of connecting this second end of the stator winding to the positive terminal of the load socket is to provide a current storage element between this positive terminal and the inverter, sufficiently sized for charging with a voltage boost, regardless of the size of the electric motor. This could be, for example, a three-phase electric motor with windings connected in a star configuration, but it could also be an electric motor with more than three phases, and the windings could be connected differently, for example in a delta configuration.

[0013] The switching device is of course a mechanical or electronic switch, or a contactor, or a relay. By "connected to", it is meant that only a few conductors or components of zero or near-zero resistance separate the elements connected together.

[0014] In this application as well, the high-voltage battery is understood to mean a battery powering the inverter and the electric motor while the vehicle is in motion, as opposed to a vehicle service battery that powers a low-voltage electrical system (e.g., 14V) to which various consumers, including the vehicle's main control unit, are connected. The high-voltage battery can therefore also be understood as a traction or propulsion battery, depending on the electric motor used. Unless otherwise specified, the battery referred to in this application is the vehicle's traction battery. Similarly, the motor and inverter in this patent application refer to an electric traction or propulsion motor and a traction or propulsion inverter for the vehicle, unless otherwise indicated. Finally, the terms "charge" and "recharge" are considered equivalent in this application.

[0015] In one embodiment of the invention, when the maximum voltage that the DC charging terminal is capable of delivering is strictly less than the maximum voltage of the high-voltage battery, the connection step is preceded by a step of closing the boost switch, and the charging step includes an operating step of the switching arm and the stator winding. Voltage boost mode. By closing the boost switch, the pre-charge capacitor is placed in parallel with the charging socket and therefore with the charging station when the latter has closed its contacts and is charging the high-voltage battery. This pre-charge capacitor helps limit voltage fluctuations at the charging station.

[0016] In this embodiment of the invention, when the maximum voltage that the DC charging station is capable of delivering is strictly lower than the maximum voltage of the high-voltage battery but higher than a high-voltage battery voltage measured before the charging step, the connection step is, for example, preceded by a step of sending a setpoint voltage value to the charging station, the setpoint voltage value being strictly lower than the high-voltage battery voltage measured before the charging step. Thus, the high-voltage battery charging step allows the high-voltage battery to be fully charged in a single operation. Alternatively, it is possible to perform two separate, end-to-end charging operations.The first charge does not use inverter switching and ends as soon as the high-voltage battery voltage reaches the charging station voltage, preferably equal to the maximum voltage the latter can achieve. The second charge uses the stator winding and the inverter in boost mode.

[0017] Furthermore, in the invention, the step of closing the lift switch is followed, before the connection step, by a pre-charging step for the pre-charge capacitor. Indeed, before connecting the pre-charge capacitor to the charging station, the pre-charge capacitor and the charging station must have substantially identical voltages to avoid a current surge that could damage vehicle components.

[0018] The pre-charge stage uses, for example, at least one of the stator windings to the second end of which the electrical branch is connected or capable of being connected, and the switching arm associated with this stator winding. The pre-charge stage comprises switching the upper switch of said switching arm, the lower switch of said switching arm remaining open, the switching occurring with a duty cycle that increases progressively. This pre-charge method makes it possible, in particular, to avoid damaging the step-up switch, which is to be sized to a minimum, by an excessive pre-charge current.

[0019] Furthermore, whether the charging step used the stator winding and the inverter in boost mode or not, the charging step is followed by a step of opening the boost switch if it was closed during the charging step, and disconnecting the electrical branch from at least the connection positive or negative connection of the charging socket. This opening and disconnecting step reconfigures the charging system so that the traction chain can be used without being interfered with by the charging system components.

[0020] In one embodiment of the invention, the second ends of the stator windings are connected together to a neutral point, and the electrical branch is capable of being connected, via its first terminal, to the neutral point and to a positive connection of the load socket. The connection step connects the electrical branch via its first terminal to the neutral point and to the positive connection of the load socket, and via its second terminal to the negative input terminal of the inverter and to the negative connection of the load socket. This embodiment of the invention is simple to implement; in particular, it does not require reconnecting the stator windings to each other.

[0021] In this embodiment of the invention, when the DC charging station is capable of delivering a voltage greater than or equal to the maximum voltage of the high-voltage battery, the charging stage uses, for example, all the switching arms of the inverter, with the upper switches of the switching arms being kept closed throughout the charging stage and the lower switches of the switching arms being kept open throughout the charging stage, so that the current from the charging station passes through all the stator windings. This implementation makes it possible, in particular, to homogenize the wear of the stator windings and thus extend their service life. Alternatively, a subset of the switching arms is used; for example, a single switching arm has an upper switch that is closed throughout the charging stage, which further limits electrical losses.

[0022] In further this embodiment of the invention, when the maximum voltage that the DC charging terminal is capable of delivering is strictly less than the maximum voltage of the high-voltage battery, the charging step includes, for example, an operating step of several switching arms and associated stator windings in voltage boost mode.

[0023] The switching arms can, for example, be used sequentially to smooth the voltage from the perspective of the high-voltage battery. Alternatively, in this charging stage, which includes a step in which several switching arms and associated stator windings operate in boost mode, at least two of the inverter's switching arms operate in opposite phase. This use of the boost function minimizes current ripple from the perspective of the high-voltage battery and prevents the creation of a magnetic field that draws current from the rotor of the electric motor.

[0024] Furthermore, to make the charging method robust against simple failures, preferably the contactor connected on one side to one of the positive or negative connections of the charging socket and on the other side to the first terminal or respectively to the second terminal of the electrical branch, is a first contactor, the charging system comprising: - a second contactor connected on one side to the second terminal or respectively to the first terminal of the electrical branch, and on the other side to the other negative or positive connection of the charging socket, or - a second contactor connected on one side to the second terminal or respectively to the first terminal of the electrical branch and on the other side to the negative input terminal of the inverter or respectively to the second end of the stator winding, and in which the connection step involves closing the first and second contactors.

[0025] Other features and advantages of the invention will become apparent from the following description on the one hand, and from several illustrative and non-limiting examples of embodiments given by reference to the accompanying schematic drawings on the other hand, in which:

[0026] [Fig-1] represents a charging system for an electric or hybrid vehicle, suitable for to allow the recharging of a high-voltage vehicle battery from a DC charging station, this charging system being suitable for use by a recharging method according to the invention of the electric or hybrid vehicle, in an embodiment of the invention,

[0027] [Fig.2] represents a variant of the charging system of [Fig.1], also suitable for to be used by the recharging process according to the invention,

[0028] [Fig.3] represents another variant of the charging system of [Fig.1], also suitable for use by the recharging process according to the invention,

[0029] [Fig.4] represents yet another variant of the charging system of [Fig.1], also suitable for use by the recharging process according to the invention,

[0030] [Fig.5] represents yet another variant of the charging system of [Fig.1], also suitable for use by the recharging process according to the invention,

[0031] [Fig.6] represents steps of the recharging process according to the invention, in a mode of the realization of the invention,

[0032] [Fig.7] represents a high-voltage battery charging step during a start-up implementation of the charging method according to the invention, in which the high-voltage battery is connected to a charging station capable of delivering a voltage greater than or equal to the maximum voltage of the high-voltage battery,

[0033] [Fig.8] represents a pre-charge step of a pre-charge capacity of the system charging of the [Fig. 1], during implementation of the charging process according to the invention, in which the high-voltage battery is connected to a charging terminal delivering a voltage lower than the voltage of the high-voltage battery, and

[0034] [Fig.9] represents a step in charging the high-voltage battery, during a implementation of the charging method according to the invention, in which the high-voltage battery is connected to a charging terminal delivering a voltage strictly lower than the voltage of the high-voltage battery.

[0035] According to one embodiment of the invention, an electric or hybrid vehicle 1 according to the invention comprises a charging system 3 represented in [Fig.1], incorporating elements of the traction chain of vehicle 1.

[0036] In this embodiment of the invention, the vehicle 1 comprises a high-voltage battery 21 with a nominal voltage of 800V, capable of powering an electric motor whose motor torque, via a transmission chain, enables the vehicle 1 to move. The electric motor of the vehicle 1 is, in this embodiment of the invention, a three-phase electric motor with a wound stator, and is represented in [Fig. 1] solely by its stator windings L1, L2, L3. The stator windings L1, L2, L3 are connected in a star configuration and connected together at one of their ends to a neutral point N of the electric motor. Of course, in alternative embodiments, the high-voltage battery may have a nominal voltage of a different value than 800V, for example 500V, and the electric motor may have a different configuration.

[0037] In order to supply the electric motor with three-phase current, an inverter 23 is interposed between the high-voltage battery 21 and the inputs of the electric motor, consisting of the ends of the stator windings L1, L2, L3 which do not form the neutral point N. The inverter 23 is therefore suitable to be connected at the input to the high-voltage battery 21, via a first relay 22 called the positive battery relay and a second relay 24 called the negative battery relay, and is connected at the output to the inputs of the electric motor. The positive battery relay 22 is of course connected by one of its terminals to a positive terminal of the high voltage battery 21 and by the other of its terminals to a positive input terminal of the inverter 23, while the negative battery relay 24 is connected by one of its terminals to a negative terminal of the high voltage battery 21 and by the other of its terminals to a negative input terminal 28 of the inverter 23.The positive battery relays 22 and negative battery relays 24 are mechanical relays or based on one or more semiconductors. A pre-charge branch is optionally connected in parallel to one of the positive battery relays 22 or negative battery relays 24; this pre-charge branch includes a pre-charge relay and a pre-charge resistor.

[0038] A smoothing capacitor 26 is connected in parallel to the terminals of the high-voltage battery 21 and to the input terminals of the inverter 23, so as to filter current ripples from the point of view of the high-voltage battery 21, during its charging. This can be achieved either through an external charging station or regenerative braking. This smoothing capacity 26 can optionally be replaced by other internal components within the high-voltage battery 21 that perform the same function.

[0039] The inverter 23 is a three-phase inverter comprising three switching arms, each comprising: - a midpoint respectively M1, M2, M3, - a lower switch respectively 1_L, 2_L, 3_L connected on one side to the respective midpoint M1, M2, M3 and on the other side to the negative input terminal 28 of the inverter 23, and - a high switch respectively 1_H, 2_H, 3_H connected on one side to the respective midpoint M1, M2, M3 and on the other side to the positive input terminal of the inverter 23.

[0040] The midpoints M1, M2, M3 correspond to the outputs of the inverter 23 and are therefore each connected to one end of a stator winding respectively L1, L2, L3, opposite to the end of this stator winding L1, L2, L3 corresponding to the neutral point N.

[0041] The upper switches 1_H, 2_H, 3_H and lower switches 1_L, 2_L, 3_L are controlled switches, for example, transistors. The charging system therefore includes a control circuit (not shown) capable of controlling these switches so as to make them switch according to a duty cycle. This control circuit is part of the charging system 3 of vehicle 1. It should be noted here that the switching of a switching arm of an inverter refers to the successive opening and closing of its upper and lower switches, the lower switch opening and closing alternately with the upper switch; that is, when the lower switch is open, the upper switch is closed, and vice versa.

[0042] The high-voltage battery 21, in this example of use of the invention, is sufficiently discharged to require recharging and therefore has a voltage Vbatt at its terminals of, for example, between 500 and 600V. The vehicle 1 is connected, via a charging socket 30 of the vehicle 1, to an external DC charging station 40. The charging socket 30 has a positive connection 302 connected via a charging cable to a positive output terminal of the charging station 40, and a negative connection 304 connected via the charging cable to a negative output terminal of the charging station 40.

[0043] The charging station 40 has internal contacts that close before the start of charging the battery 21. During this charging, it behaves as a voltage source, with VDC voltage at its terminals.

[0044] The charging system 3 of the vehicle 1 comprises an electrical branch 32, a first terminal 322 of which is connected to the positive connection 302 of the charging socket 30 and of which a second terminal 324 is capable of being connected, via a first contactor 36 of the charging system 3, to the negative connection 304 of the charging socket 30. The first contactor 36 is thus connected on one side to the negative connection 304 of the charging socket 30 and on the other side to the second terminal 324 of the electrical branch 32.

[0045] The electrical branch 32 comprises a pre-charge capacitor 326 and a so-called step-up switch 328 mounted in series with respect to each other. In this embodiment of the invention, one of the terminals of the step-up switch 328 is connected to the first terminal 322 of the electrical branch 32, and one of the terminals of the pre-charge capacitor 326 is connected to the second terminal 324 of the electrical branch 32.

[0046] The pre-charge capacitor 326 and the boost switch 328 form a pre-charge system at the input of the charging system 3, the first contactor 36 being closed only after the pre-charge capacitor 326 has been pre-charged by the battery 21, before the latter is recharged. The pre-charge capacitor 326 notably filters voltage variations and stabilizes the voltage at the charging terminal 40 during the recharging of the high-voltage battery 21.

[0047] The step-up switch 328 is a mechanical relay or an electronic switching component, consisting of one or more transistors. It is designed to withstand a voltage of approximately 1000V and a current of approximately 35A under nominal operating conditions. In other words, it is less bulky and less expensive than the first contactor 36, which is designed to withstand a voltage of approximately 1000V and a current of approximately 500A under nominal operating conditions.

[0048] In this embodiment of the invention, the charging system 3 also includes a second contactor 38, capable of connecting the first terminal 322 of the electrical branch 32 to the neutral point N of the electric motor. This second contactor 38 is also designed to withstand a voltage of approximately 1000V and a current of approximately 500A under nominal operating conditions. The first contactor 36 and the second contactor 38 are mechanical relays or relays based on one or more semiconductors.

[0049] The second terminal 324 of the electrical branch 32 is connected to the negative input terminal 28 of the inverter 23.

[0050] As will be seen later, the inverter assembly 23 and stator windings L1, L2, L3 is capable of functioning as a voltage booster during a charging of the high voltage battery 21 during which the voltage VDC supplied by the charging terminal 40 is strictly less than the voltage Vbatt of the high voltage battery 21.

[0051] The neutral point N then forms a positive input terminal of the voltage booster, and the negative input terminal 28 of the inverter 23 then forms a negative input terminal of the voltage booster. The positive and negative input terminals 28 of The inverter 23 also forms the positive and negative output terminals of the voltage booster. This booster can therefore be connected at the input to the pre-charge capacitor 326 via the second contactor 38 and the boost switch 328, and can be connected at the output to the battery 28 via the positive battery relay 22 and the negative battery relay 24.

[0052] Figure 2 shows an alternative embodiment of the invention, the elements identical to those of the main embodiment of the invention being referenced in the same way. In this alternative embodiment, a charging system 3b of an electric or hybrid vehicle 1b, suitable for use by a charging method according to the invention of the vehicle 1b, differs from the charging system 3 of Figure 1 only in its electrical branch 32b, which differs from the electrical branch 32 by the respective positions of the pre-charge capacitor 326 and the lift switch 328.

[0053] The electrical branch 32b does indeed always include a pre-charge capacitor 326 and a lift switch 328 mounted in series, but in this variant of the invention, one of the terminals of the lift switch 328 is connected to the second terminal 324 of the electrical branch 32b, and one of the terminals of the pre-charge capacitor 326 is connected to the first terminal 322 of the electrical branch 32b.

[0054] It should be noted that the first terminal 322 of the electrical branch 32b is connected to the positive connection 302 of the load socket 30 and to the second contactor 38, while the second terminal 324 of the electrical branch 32b is connected to the negative input terminal 28 of the inverter 23 and is suitable to be connected to the negative connection 304 of the load socket 30 via the first contactor 36.

[0055] Figure 3 shows another embodiment of the invention, the elements identical to those of the main embodiment of the invention being referenced in the same way. In this other embodiment, a charging system 3c of an electric or hybrid vehicle, suitable for use by a charging method according to the invention of the vehicle, differs from the charging system 3 of Figure 1 only in the position of the second contactor 38. Indeed, in this other embodiment, the second contactor 38 is connected on the one hand to the positive connection of the charging socket 30 and on the other hand to the first terminal of the electrical branch 32.

[0056] Of course this other embodiment can be combined with the previous one, that is to say that the positions of the lift switch 328 and the pre-charge capacitance 326 can be reversed as on the electrical branch 32b.

[0057] Figure 4 shows yet another embodiment of the invention, the elements identical to those of the main embodiment of the invention being referenced in the same way. In this other embodiment, a 3D charging system for an electric or hybrid vehicle, suitable for use by a process charging according to the invention of vehicle Id, differs from the charging system 3 of [Fig.1] only by the positions of the first contactor 36 and the second contactor 38.

[0058] Indeed, in this other embodiment, the first contactor 36 is connected on one side to the positive connection 302 of the load socket 30 and on the other side to the first terminal 322 of the electrical branch 32, while the second contactor 38 is connected on one side to the second terminal 324 of the electrical branch 32 and on the other side to the negative input terminal 28 of the inverter 23.

[0059] This last embodiment can be combined with the variant in which the positions of the lift switch 328 and the pre-charge capacitor 326 are reversed, as in the electrical branch 32b. This possibility is illustrated [Fig. 5], showing a 3e charging system for an electric or hybrid vehicle, suitable for use by a charging method according to the invention. Compared to the 3e charging system of [Fig. 1], the only differences in this 3e charging system are as follows: - Electrical branch 32 is replaced by electrical branch 32b, and - the first contactor 36 is connected on one side to the positive connection 302 of the load socket 30 and on the other side to the first terminal 322 of the electrical branch 32b, while the second contactor 38 is connected on one side to the second terminal 324 of the electrical branch 32b and on the other side to the negative input terminal 28 of the inverter 23.

[0060] We now describe in relation to [Fig.6], a method of recharging 100 according to the invention, of the vehicle 1 equipped with the charging system 3. This method is also usable for recharging the vehicle 1b, the or Id.

[0061] The charging process 100 is implemented by the vehicle 1, in particular by a computer of the vehicle 1, by its charging system 3, its stator windings L1, L2, L3 and its inverter 23.

[0062] Initial preliminary steps of the charging method 100, not shown, consist in particular of connecting a charging cable between the charging station 40 and the charging socket 30, and of communication between the vehicle 1 and the charging station 40 so that the vehicle 1 and the charging station 40 exchange information useful for charging the high-voltage battery 21, in particular the maximum voltage and / or a maximum current that the station can deliver, a current or a setpoint voltage provided by the vehicle 1.

[0063] It should be noted that during these preliminary steps, the setpoint voltage supplied by the vehicle 1 to the charging station 40 is by default the maximum voltage that the charging station 40 can supply, except in the case where this maximum voltage that the charging station 40 can supply is strictly less than the maximum voltage of the high-voltage battery 21 but greater than or equal to the battery voltage Vbatt high voltage 21 at the start of charging. In this latter case, the setpoint voltage supplied by the vehicle 1 to the charging station 40 takes a value strictly lower than the voltage Vbatt of the high voltage battery 21 at the start of charging.

[0064] These preliminary steps may also include safety check steps related for example to the proper functioning of the contactors 36, 38, relays 22, 24 and the lift switch 328 of vehicle 1.

[0065] It is assumed that following these preliminary steps, the contactors 36, 38 and the lift switch 328 are open, the positive battery relays 22 and negative battery relays 24 being closed.

[0066] Following these preliminary steps, the vehicle computer 1 determines 102 whether the charging station 40 can deliver a VDC voltage greater than or equal to the maximum voltage of the high-voltage battery 21.

[0067] If this is the case (branch Y), the next step is a connection step 104 to the charging terminal 40, which results in the closing of the first and second contactors 36, 38, with the step-up switch 328 remaining open. This also amounts to ensuring an electrical connection from the first terminal 322 of the electrical branch 32 to the neutral point N and to the positive connection 302 of the charging socket 30, and an electrical connection from the second terminal 324 of the electrical branch 32 to the negative input terminal 28 of the inverter 23 and to the negative connection 304 of the charging socket 30.

[0068] The next step, represented [Fig.7], is a charging step 106 during which the VDC voltage across the terminals of the charging terminal 40 is strictly greater than the maximum voltage of the high-voltage battery 21, i.e. strictly greater than 800V in this embodiment of the invention. In this charging step 106, a positive lin current from the charging terminal 40 passes through the second contactor 38 of the charging system 3 (or the first contactor 36 in the case of the charging system 3d or 3e), then splits into three currents II, 12, 13 passing respectively through the stator windings L1, L2, L3, then the upper switches 1_H, 2_H, 3_H of the inverter 23, before arriving at the high-voltage battery 21. In this charging step 106, the switching arms of the inverter 23 do not switch, in other words the duty cycle of the upper switches 1_H, 2_H, 3_H is 1.

[0069] Thus, the linear current from the charging station 40 is distributed among all the stator windings L1, L2, L3, and the upper switches 1_H, 2_H, 3_H, which allows them to be sized for a current flowing through them that is lower than the linear current. In alternative embodiments of the invention, only one or two upper switches of the inverter 23 are closed, the other switches of the inverter 23 being open. In these alternative embodiments, the linear current therefore passes through only one stator winding. and a single high switch, or in two stator windings only and two high switches only.

[0070] Finally, a last step 108 of the charging process 100 is the disconnection of the charging system 3 from the charging station 40, which results in the opening of the first and second contactors 36, 38.

[0071] When, following the preliminary steps of the charging process 100, the vehicle computer 1 determines (branch N) that the charging station 40 cannot deliver a DC voltage greater than or equal to the maximum voltage of the high-voltage battery 21, then the next step is a closing step 110 of the boost switch 328, and a closing of the second contactor 38 (except possibly for the charging system 1, where the second contactor 38 may remain open), the first contactor 36 remaining open. In other words, in this closing step 110, the pre-charge capacitor 326 is connected to the input of the voltage booster formed by the assembly of stator windings L1, L2, L3 and inverter 23, without connecting the pre-charge capacitor 326 or the charging system 3 to the charging station 40.

[0072] The next step 112 is then the pre-charging of the pre-charge capacity 326 by the high-voltage battery 21, so that the pre-charge capacity 326 reaches a voltage level substantially equal to the voltage VDC expected to be delivered by the charging terminal 40 at the start of charging the high-voltage battery 21. This voltage VDC is strictly lower than the voltage Vbatt of the high-voltage battery 21 as measured during the preliminary steps of the charging process 100.

[0073] During this pre-charge step 112, shown in [Fig. 8], each high-voltage switch 1_H, 2_H, 3_H of the high-voltage battery 21 is switched synchronously, for example, with a duty cycle that increases progressively, for example, along a very shallow ramp, for example, of 1.1%, so that the pre-charge current of the pre-charge capacitance 326 remains below a maximum current beyond which the step-up switch 328 would be damaged. In [Fig. 8], each high-voltage switch 1_H, 2_H, 3_H carries a current Ip, these high-voltage switches being shown during a closing phase.

[0074] The duty cycle increases from a minimum value corresponding to a closing time over a switching period, between 100qs (microseconds) and 200qs. With a slope of 1.1%, the minimum value at which the duty cycle starts is, for example, 30qs.

[0075] Following this pre-charge step 112, the voltage across the pre-charge capacitance 326 is, for example, 396V when the expected VDC voltage to be delivered is 400V.

[0076] The next step 114 is then the connection of the charging system 3 to the charging station 40, the charging system 3 being ready for such charging. During this In step 114, the first contactor 36 and the second contactor 38 are closed, so the pre-charge capacity 328 is connected in parallel to the charging terminal 40, which limits voltage variations from the point of view of the charging terminal 40.

[0077] Indeed, the next step 116 is a recharging of the high-voltage battery 21, using in voltage boost mode all the stator windings L1, L2, L3 and of the inverter 23, that is to say a switching of the switching arms of the inverter 23, which causes voltage variations. By way of example, this switching is carried out at a frequency above 500 Hz, typically between 15 kHz and 30 kHz.

[0078] This charging step 116 is shown [Fig.9]. During this charging step 116, the VDC voltage delivered by the charging terminal 40 is strictly less than the Vbatt voltage of the high-voltage battery 21, as measured at the start of charging.

[0079] Figure 9 illustrates a possible example of such a charging operation, using the three switching arms of the inverter. In Figure 9, the moment is frozen at a point where the charging current flowing through the second contactor 38 is divided between, on the one hand, a current 14 passing through a first stator winding L1 and an upper switch 1H of a first switching arm of the inverter 23, so as to charge the high-voltage battery 21, and on the other hand, a current 15 and a current 16 passing through the second and third stator windings L2, L3 and the lower switches 2L, 3L of a second and third switching arm of the inverter 23, so as to charge these second and third stator windings L2, L3 with energy. Thus, the first switching arm switches in opposite phase to the second and third switching arms, which switch in phase.It is understood that when the first stator winding L1 charges with energy, the second and third stator windings L2, L3 discharge into the high-voltage battery 21 and vice versa, at a high switching frequency, illustrated by the dotted lines on the top and bottom switches of the inverter 23.

[0080] This use of the voltage booster reduces current ripple at the high-voltage battery 21 compared to synchronous switching of all the upper switches, while also limiting the voltage induced in the rotor. When the rotor is wound, it is, for example, short-circuited during the charging stage to prevent any voltage induced in the rotor. Of course, the choice of switching arms alternating with each other is modifiable. Alternatively, the three switching arms of the inverter switch in phase during this charging stage 116, or are phase-shifted by 120°.

[0081] Of course, many embodiments of the invention are possible, as the switching arms can operate differently. The charging step 116 can in effect of using only one or two switching arms of inverter 23. When only two switching arms are used to charge the high voltage battery, the choice of the switching arm which does not switch is determined for example according to the position of the rotor, in order to minimize the movement of the latter.

[0082] Finally, the charging step 116 is followed by a step 118 of opening the lift switch 328 and opening the first and second contactors 36, 38.

[0083] Of course, the invention is not limited to the examples just described, and many modifications can be made to these examples without departing from the scope of the invention. In particular, the characteristics of the different embodiments of the invention envisaged in this application can be combined to carry out the invention, provided that these embodiments are not incompatible with each other.

Claims

1. Demands Method (100) for recharging an electric or hybrid vehicle (1, 1b, le, Id), the electric or hybrid vehicle (1, 1b, le, Id) comprising: -a high-voltage battery (21), - an electric motor comprising stator windings (L1, L2, L3), each having a first and a second end; - an inverter (23) suitable for connection at the input to the high-voltage battery (21) and at the output to the first ends of the stator windings (L1, L2, L3) of the electric motor, the inverter (23) comprising at least one switching arm per stator winding (L1, L2, L3), each switching arm comprising an upper switch (1_H, 2_H, 3_H) connected between a midpoint (M1, M2, M3) of the switching arm and a positive input terminal of the inverter (23), and a lower switch (1_L, 2_L, 3_L) connected between a midpoint (M1, M2, M3) of the switching arm and a negative input terminal (28) of the inverter (23), the midpoint (M1, M2, M3) being connected to the first end of the stator winding (L1, L2, L3), and - a charging system (3, 3b, 3c, 3d) comprising: - a charging socket (30) suitable for connection to a DC charging station (40), - an electrical branch (32, 32b) capable of being connected by a first (322) of its terminals, to at least the second end of one of the stator windings (L1, L2, L3) and to a positive connection (302) of the load socket (30), and by a second (324) of its terminals, to a negative input terminal (28) of the inverter (23) and to a negative connection (304) of the load socket (30), the electrical branch (32, 32b) comprising a series arrangement of a pre-charge capacitor (326) and a switch (328) called a step-up switch, - at least one contactor (36) connected on the one hand to one of the positive or negative connections (302, 304) of the charging socket (30) and on the other hand to the first terminal (322) or respectively to the second terminal (324) of the electrical branch (32, 32b), the charging method (100) comprising a connection step (104, 114) of the electrical branch (32, 32b) by the first (322) of its terminals, to the second end of the stator winding (L1, L2,

2.

3. L3) and to the positive connection (302) of the charging socket (30), and by the second (324) of its terminals, to the negative input terminal (28) of the inverter (23) and to the negative connection (304) of the charging socket (30), and a charging stage (106, 116) of the high-voltage battery (21) by a DC charging terminal (40), to which the charging socket (30) is connected, the charging method (100) being characterized in that, when the DC charging terminal (40) is capable of delivering a voltage (VDC) greater than or equal to a maximum voltage of the high-voltage battery (21), then during the charging stage (106), the boost switch (328) is open, and the charging stage (106) uses at least one switching arm of the inverter (23), the boost switch (1_H, 2_H, 3_H) of the switching arm being kept closed throughout the charging step (106) and the bottom switch (1_L, 2_L,3_L) of the switching arm being kept open throughout the charging step (106), so that at least a part of the current (lin) from the charging terminal (40) passes through the stator winding (L1, L2, L3). Method (100) of charging an electric or hybrid vehicle (1, 1b, le, Id) according to the preceding claim, wherein when a maximum voltage that the DC charging station (40) is capable of delivering is strictly less than the maximum voltage of the high-voltage battery (21), the connection step (114) is preceded by a closing step (110) of the boost switch (328), and the charging step (116) includes an operating step of the switching arm and the stator winding (L1, L2) in voltage boost mode. Method (100) of charging an electric or hybrid vehicle (1, 1b, le, Id) according to the preceding claim, wherein when the maximum voltage that the DC charging station (40) is capable of delivering is strictly less than the maximum voltage of the high-voltage battery (21) but greater than a voltage of the high-voltage battery (21) measured before the charging step (116), the connection step is preceded by a step of sending a setpoint voltage value to the charging station (40), the setpoint voltage value being strictly less than the voltage of the high-voltage battery (21) measured before the charging step (116).

4. Method (100) of recharging an electric or hybrid vehicle (1, 1b, le, Id) according to claim 2 or 3, wherein the closing step (110) of the lift switch (328) is followed, before the connection step (114), by a pre-charging step (112) of the pre-charging capacity (326).

5. Method (100) of recharging an electric or hybrid vehicle (1, 1b, le, Id) according to the preceding claim, wherein the pre-charge step (112) uses at least one of the stator windings (L1, L2, L3) to the second end of which the electrical branch (32, 32b) is connected or capable of being connected, and the switching arm associated with this stator winding (L1, L2, L3), the pre-charge step (112) comprising a switching of the upper switch (1_H, 2_H, 3_H) of said switching arm, the lower switch (1_L, 2_L, 3_L) of said switching arm remaining open, the switching being effected with a duty cycle increasing progressively.

6. Method (100) of charging an electric or hybrid vehicle (1, 1b, le, Id) according to any one of the preceding claims, wherein the charging step (106, 116) is followed by an opening step (118) of the lift switch (328) when it was closed during the charging step (116), and disconnection (108, 118) of the electrical branch (32, 32b) of at least the positive connection (302) or the negative connection (304) of the charging socket (30).

7. A method (100) for charging an electric or hybrid vehicle (1, 1b, 1e, 1d) according to any one of the preceding claims, wherein the second ends of the stator windings (L1, L2, L3) are connected together to a neutral point (N) and the electrical branch (32, 32b) is capable of being connected by the first (322) of its terminals to the neutral point (N) and to a positive connection (302) of the charging socket (30), the connection step (104, 114) connects the electrical branch (32, 32b) by the first (322) of its terminals to the neutral point (N) and to the positive connection (302) of the charging socket (30), and by the second (324) of its terminals to the negative input terminal (28) of the inverter (23) and to the negative connection (304) of the socket. charge (30).

8. A method (100) for recharging an electric or hybrid vehicle (1, 1b, le, Id) according to the preceding claim, wherein when the DC charging station (40) is capable of delivering a voltage (VDC) greater than or equal to the maximum voltage of the high voltage battery (21), the charging stage (106) uses all the switching arms of the inverter (23), the upper switches (1_H, 2_H, 3_H) of the switching arms being kept closed throughout the charging stage (106) and the lower switches (1_L, 2_L, 3_L) of the switching arms being kept open throughout the charging stage (106), so that the current (lin) from the charging station (40) passes through all the stator windings (L1, L2, L3).

9. Method (100) of charging an electric or hybrid vehicle (1, 1b, le, Id) according to claim 7 or 8 sockets in combination with claim 2, wherein when the maximum voltage that the DC charging station (40) is capable of delivering is strictly less than the maximum voltage of the high-voltage battery (21), the charging step (116) comprises an operating step of several switching arms and associated stator windings (L1, L2) in voltage boost mode.

10. Method (100) of charging an electric or hybrid vehicle (1, 1b, le, Id) according to the preceding claim, wherein during the charging step (116) comprising an operating step of several switching arms and associated stator windings (L1, L2) in voltage boost mode, at least two of the switching arms of the inverter (23) operate in opposite phase.

11. A method (100) for charging an electric or hybrid vehicle (1, 1b, 1e, 1d) according to any one of the preceding claims, wherein the contactor (36) connected on the one hand to one of the positive (302) or negative (304) connections of the charging socket (30) and on the other hand to the first terminal (322) or respectively to the second terminal (324) of the electrical branch (32, 32b), is a first contactor, the charging system (3, 3b, 3c, 3d) comprising: - a second contactor (38) connected on the one hand to the second terminal (324) or respectively to the first terminal (322) of the electrical branch (32, 32b), and on the other hand to the other of the negative (304) or positive (302) connections of the charging socket (30), or alternatively - a second contactor (38) connected to a part to the second terminal (324) or respectively to the first terminal (322) of the electrical branch (32, 32b) and on the other hand to the input terminal negative (28) of the inverter (23) or respectively to the second end of the stator winding (L1, L2, L3), and in which the connection step (104, 114) involves the closing of the first (36) and second contactor (38).

Images