Electric vehicle, charging station, and method for exchanging power between vehicle and station

Abstract

The invention relates to an electric vehicle (10), a charging station (12), and a method for exchanging power between the vehicle and the station. The vehicle comprises: a control module (22) for communicating with a module (24) via a cable (20) for controlling a power converter (18) of the station; a low-voltage power source (34); means (S3) for connecting the low-voltage power source to the cable to supply power to the module for controlling the station; and an impedance (Rpv) similar to the impedance (Rpb) of the station, through which the voltage source (32) of the station can supply power to the module for controlling the station, wherein the impedance of the vehicle is arranged between the control module and the cable; and a switch (S4) for short-circuiting the impedance (Rpv) of the vehicle.

Description

[0001] The invention belongs to the field of electric vehicles and relates to reversible charging of batteries of electric vehicles.

[0002] To recharge an electric vehicle, the vehicle's charging socket is typically connected to a charging station via a charging cable. The charging station then transfers power from the power distribution network to the vehicle. This mode of operation is known as G2V (an acronym for Grid-to-Vehicle). The charging station typically includes a converter that performs what's known as AC / DC conversion, converting the AC voltage on the power distribution network to the DC voltage used to recharge the vehicle's battery.

[0003] The charging station can also be used reversibly, allowing power to be sent from the vehicle to the power distribution network. This mode of operation is called V2G (an acronym for Vehicle-to-Grid). The electric vehicle is thus used as a power source. When the grid requires it, the battery of the electric vehicle is commanded to discharge into the power distribution network. To this end, the charging station is equipped with a reversible converter that performs the AC / DC conversion described above for recharging the vehicle, or the reverse conversion, known as DC / AC conversion, i.e., converting the DC voltage delivered by the vehicle battery into the AC voltage of the grid.

[0004] A variant of the V2G operating mode can be implemented without a grid connection, allowing vehicles to supply power to loads not connected to the distribution network. This variant is known as V2H (Vehicle-to-Home). This allows the creation of regional grids, particularly in a home environment, that form islands with a limited number of connected loads. In contrast to the V2G mode, where the distribution network imposes its voltage and frequency on the station, the charging station's converter regulates the voltage and frequency of the regional grid.

[0005] In various operating modes, the vehicle and station exchange operational data in addition to transferring power. This data exchange allows the station's converter's DC input voltage to be adjusted to the vehicle's battery voltage. More specifically, in V2G or V2H mode, power transfer from the battery to the terminals begins only when the difference between the vehicle's battery voltage and the station's converter's input voltage is less than a given value (typically 20 volts). If this condition is not met, significant current drain occurs, potentially damaging the vehicle's battery.

[0006] The station communicates with the vehicle to exchange data that allows the converter's DC input voltage to be adjusted. To this end, the station includes a driver module for driving the converter. When the grid is recharging the vehicle's battery or in V2G mode, the station and its driver module are powered by the distribution network. Before power transfer begins, data can be exchanged between the vehicle and the station. However, in V2H operating mode, the local grid is typically deactivated whenever the vehicle is not supplying power to the grid. Consequently, the local grid cannot supply power to the station, particularly its driver module. Without power to the driver module, data communication between the vehicle and the station cannot be established.

[0007] In some standards, notably the CHAdeMO standard (which originated in Japan and is widely used in Europe), the cable connecting the vehicle and the station provides a high-power conductor that allows power to be transmitted and a low-power conductor that enables a low-voltage power supply that can be used to power the drive module of the station from the vehicle. In contrast, in other standards, notably the CCS standard (which is also widely used in Europe), no low-voltage power supply is provided from the vehicle to the station to prevent power from being supplied to the drive module before power begins to be transmitted from the vehicle to the station. The CCS standard (an acronym for Combined Charging System) was launched by the CharIN EV Alliance, which was founded by German motor vehicle manufacturers such as BMW, Daimler, Opel and Volkswagen.

[0008] The present invention overcomes this difficulty of not having a standard for low voltage power supply by allowing power to be transferred from the vehicle to the station (whether the station is powered in V2G mode or not powered in V2H mode).

[0009] To this end, a subject of the invention is an electric vehicle intended to exchange power with a station, comprising a control module intended to communicate via a cable with a drive module in order to drive the power converter of the station. The vehicle further comprises a low-voltage power source, connection means for connecting the low-voltage power source to the cable in order to supply power to the drive module of the station, and an impedance similar to the impedance of the station, through which the voltage source of the station can supply power to the drive module of the station, the impedance of the vehicle being arranged between the control module and the cable. In addition, the vehicle comprises a switch allowing the impedance of the vehicle to be short-circuited. An impedance "similar" to another impedance is understood to mean an impedance having a value substantially equal to that of the other impedance, for example having a value that differs by no more than 5% from that of the other impedance.

[0010] The presence of impedance in the vehicle allows the use of standard stations and cables provided for G2V and V2G operating modes in V2H mode without modifying the stations and cables, even if the voltage source of the station is inoperative due to the absence of a connection between the station and a grid capable of supplying power to the station.

[0011] Advantageously, the vehicle further comprises temporary means for limiting the power transferred between the vehicle and the station.

[0012] Another subject of the invention is a station intended to exchange electric power with an electric vehicle, comprising a power converter and a driver module for driving the power converter, the driver module being intended to communicate with a control module of the vehicle via a cable. The station further comprises means for receiving, via the cable, a voltage originating from a low-voltage power supply of the vehicle in order to power the driver module, and a voltage source capable of generating a signal intended for the control module of the vehicle via the impedance of the station, the cable, and the impedance of the vehicle, which can be short-circuited by a switch of the vehicle.

[0013] Advantageously, the means for receiving a supply voltage comprise a switch allowing disconnection of the voltage source.

[0014] Another subject of the invention is a method of implementing a vehicle and a station according to the invention, the vehicle and the station being intended to exchange electric power, the method comprising connecting the following operations:

[0015] - supply power to the station's drive module via the vehicle's low-voltage power supply,

[0016] - starting data exchange via the cable in order to drive the power converter, thereby receiving power from the vehicle,

[0017] -Transmitting electricity from the vehicle to the station.

[0018] Advantageously, the transmission of electricity from the vehicle to the station comprises the following two consecutive steps:

[0019] - a step of pre-charging with a limited current as long as the voltage difference between the battery and the converter is greater than a given value,

[0020] - the step of performing power transfer without current limitation as soon as the voltage difference between the battery and the converter is less than or equal to the given value.

[0021] The invention will be better understood and other advantages will become apparent on reading the detailed description of an embodiment given by way of example, which description is illustrated by the accompanying drawings in which:

[0022] [ Figure 1 ] Figure 1 An electric vehicle connected to a charging station in the context of the present invention is shown;

[0023] [ Figure 2 ] Figure 2 An example of a connector that allows a vehicle and a charging station to be connected is shown;

[0024] [ Figure 3 ] Figure 3 A portion of a circuit diagram showing a vehicle and a charging station;

[0025] [ Figure 4 ] Figure 4 Another portion of a circuit diagram showing a vehicle and a charging station;

[0026] [ Figure 5 ] Figure 5 An example of a flow chart illustrating the operation of the method of the present invention.

[0027] For purposes of clarity, the same reference numbers will be used throughout the drawings to represent similar elements.

[0028] Figure 1 An electric vehicle 10 is shown connected to a charging station 12. The vehicle 10 is equipped with a main battery 14, the nominal voltage of which is, for example, 400 VDC. The station 12 primarily allows the battery 14 to be recharged. To this end, the station 12 is generally stationary and connected to a power distribution network 16, for example a 220 VAC national grid. The station 12 comprises a converter 18 configured to convert the electricity received from the grid 16 into electricity capable of recharging the battery 14. The converter is, for example, a reversible AC / DC converter, which also enables a V2G mode or a V2H mode to be adopted. A cable 20 connects the vehicle 10 with the station 12. The cable 20 allows the power to be transmitted from the station 12 to the vehicle 10. The vehicle 10 comprises a control module 22 which in particular allows the charging of the battery 14 to be managed. In Figure 1 In the figure, control module 22 is shown at a distance from vehicle 10 for greater clarity. Charging station 12 includes a drive module 24 that allows converter 18 to be driven. Drive module 24 is also shown at a distance from station 12 for greater clarity. Control module 22 and drive module 24 exchange information, particularly to adjust the DC voltage of converter 18 according to the voltage of battery 14. This information can be exchanged in a wired manner via cable 20.

[0029] Figure 2 An example of a connector 30 is shown, which is present at the end of the cable 20 and is intended to be connected to a socket of the vehicle 10 . Figure 2The distribution of the terminals of the connector 30 used in the CCS standard is shown. Of course, the present invention can be implemented in other standards. The connector 30 includes nine terminals, which are labeled L1, L2, L3, N, PE, CP, PP, DC- and DC+. The terminals L1, L2, L3, N and PE allow power to be transmitted with AC current, and the terminals DC+ and DC- allow power to be transmitted with DC current. The terminals L1, L2 and L3 correspond to electrical phases, the terminal N corresponds to electrical neutrality, and the terminal PE corresponds to equipotential grounding. As a variant, a connector 30 is used that only has the terminals DC-, DC+, PE, CP and PP. The terminals CP and PP allow information to be transmitted between the control module 22 of the vehicle 10 and the drive module 24 of the station 12. In the CCS standard, it is possible to Figure 3 The resistor Rc seen in FIG is connected between the terminals PP and PE and allows the presence of the cable 20 to be detected.

[0030] As mentioned above, the converter 18 can be bidirectional and allow the transfer of power originating from the vehicle 10, for example to send power to the grid 16 in a V2G mode. In this mode, the drive module 24 can be powered by the grid 16 and establish a dialogue with the control module 22, which is itself powered by the battery 14 of the vehicle 10.

[0031] The present invention relates to situations where there is no distribution grid 16 and it is desired to power loads connected to stations 12 using power drawn from batteries 14 of vehicles 10. These loads powered by stations 12 may form a regional grid 26, sometimes referred to as an island.

[0032] Figure 3 An example of a circuit diagram is partially shown, the components of which are arranged in the vehicle 10, the station 12, and the cable 20. In order not to overload the diagram, the connections corresponding to the terminals DC+ and DC-, which allow power to be transmitted as a DC current between the vehicle 10 and the station 12, are not shown. Only the connections corresponding to the terminals CP, PP, and PE are shown.

[0033] When station 12 is recharging battery 14 or in V2G mode, drive module 24 is powered by station 12. This power source can be a dedicated power source or use converter 18. In V2H mode, no power source is available in station 12, and vehicle 10 replaces the station to supply power to drive module 24 via cable 20 (and, in the example shown, via terminal CP). To this end, vehicle 10 includes a low-voltage power source 34 and a connection device, here formed by switch S3, for connecting low-voltage power source 34 to terminal CP. On the station 12 side, switch S6 allows terminal CP to be connected to drive module 24.

[0034] When station 12 is powered by distribution network 16, voltage source 32 in station 12 transmits signals to terminal CP. In vehicle 10, these signals are transmitted to control module 22 via diode D and a bridge voltage divider formed by resistors R2 and R3. Resistor R2 can be activated by switch S2. When station 12 is powered by distribution network 16, terminal CP is directly connected to the anode of diode D. In the context of the present invention, this direct connection can be disconnected. More specifically, switch S4 allows this direct connection to be interrupted, thereby restoring the signal originating from station 12 and interrupted when voltage source 32 ceases operation in V2H mode. More specifically, bias resistor Rpb is connected in series between voltage source 32 and terminal CP. When voltage source 32 ceases operation in V2H mode, another bias resistor Rpv replaces resistor Rpb to bias control module 22. Resistor Rpv has the same resistance as resistor Rpb and is arranged in vehicle 10, more specifically, between terminal CP and control module 22. Resistor Rpv is arranged in parallel with switch S4. Therefore, to allow resistor Rpv to contribute to biasing control module 22, it is sufficient to open switch S4. To prevent interference with biasing control module 22, when resistor Rpv is used, switch S5 can be arranged in station 12 to disconnect resistor Rpb from terminal CP.

[0035] Biasing the control module 22 refers to supplying a voltage to the module 22 that allows it to detect the system status. Specifically, the module 22 receives different voltages depending on the position of various switches, enabling it to detect the system status. The control mode of the module 22 depends on the received voltage. Here, bias resistor Rpv allows the control module 22 to detect the V2H mode with 100% modulation while complying with the CCS standard.

[0036] More generally, the two resistors Rpv and Rpb can be impedances (resistors to which capacitors and / or inductors can be added if necessary) that perform similar functions for the control module 22 of the vehicle 10 or for the drive module 24 in combination with the voltage source 32 with 100% modulation of the station 12 (for impedance Rpb) and in combination with the low-voltage power supply 34 of the vehicle 10 (for impedance Rpv).

[0037] The voltage source 32 may be a DC voltage source whose pulse width is modulated according to the type of information transmitted from the station 12 to the control module 22 when the station 12 is recharging the battery 14 of the vehicle 10 or in V2G mode. In V2H mode, in the context of the present invention, power is supplied to the drive module 24 using terminal CP. The voltage delivered by the power source 34 is DC. In other words, the modulation at terminal CP is 100%. However, 100% modulation is interpreted in the CCS standard as a request to urgently stop charging the battery 14. V2H mode is initiated by the vehicle 10, and the vehicle's control module 22 is configured not to expect anything other than 100% modulation and not to interpret it as an emergency stop request. Once the drive module 24 is powered, the station 12 can establish a dialogue with the vehicle 10's control module 22, with the vehicle 10 acting as the master. The vehicle's control module 22 can specifically request that the station 12 terminate V2H mode at a specific setpoint different from the 100% modulation of the power source 34.

[0038] Once a dialogue has been established between the drive module 24 of the station 12 and the control module 22 of the vehicle 10, power can be transferred from the battery 14 of the vehicle 10 to the station 12. Figure 4 The structure shown in is transferred in two steps.

[0039] exist Figure 4 In FIG, inside the vehicle 10, the battery 14 and the control module 22 are shown. Inside the station 12, the converter 18 and the drive module 24 are shown. The cable 20 uses the terminals CP and PE for the dialogue between the control module 22 and the drive module 24. The power transmission is connected to the negative terminal of the battery using the terminal DC- and to the positive terminal of the battery using the terminal DC+, the voltage of the battery being, for example, 400 VDC. Figure 2 In FIG, terminals L1, L2 and L3 for supplying power with AC current are also shown. Specifically, the CCS standard allows charging the battery 14 from a station that delivers power in the form of AC voltage or DC voltage. When power is delivered in the form of DC voltage, only the terminals DC- and DC+ are used.

[0040] After establishing power supply from vehicle 10 to drive module 24 of station 12, power transfer from battery 14 to station 12 can be initiated directly. To this end, the connection between battery 14 and converter 18 via terminal DC+ includes contactor S8 connected in series with the conductor passing through terminal DC+. Contactor S8 is, for example, located in vehicle 10 and driven by control module 22. This initiation can be performed without restriction. However, the input voltage of converter 18 may not be optimally regulated, resulting in a large current being drawn through the conductor passing through terminal DC+. This current draw could damage battery 14 and contactor S8. To limit this current draw, it is advantageous to begin with a pre-charging step with a limited current. This step is performed, for example, by a power resistor R arranged in series with contactor S8 (e.g., arranged in vehicle 10). By way of example, for a 400 VDC battery, the resistance of resistor R may be on the order of 100 ohms. When contactor S8 is closed, the current is limited to 4 amperes, even though converter 18 is equivalent to a short circuit between terminals DC+ and DC-. However, limiting the current allows the converter 18 to start operating, in particular by increasing its input voltage to a voltage close to the voltage delivered by the battery 14. More specifically, the pre-charging step is continued as long as the voltage difference between the battery 14 and the converter 18 is greater than a given value. When the voltage difference becomes less than or equal to this given value, the current limitation can be omitted. For this purpose, the vehicle 10 includes another contactor S9 arranged in parallel with the resistor R and allowing this resistor to be short-circuited. The contactor S9 is driven by the control module 22. In order to drive the contactor S9, the control module 22 exchanges with the drive module 24 to compare the voltage of the battery 14 with the input voltage of the converter 18 on the DC side.

[0041] Figure 5 An example of a flow chart illustrating the operation of the method of the present invention is shown. Block 40 shows that the drive module 24 of the station 12 is powered by the power supply 34 of the vehicle 10. Once this power supply is established, an information exchange is established between the drive module 24 of the station 12 and the control module 22 of the vehicle 10, which is shown in block 42. Once this information exchange is established, power transmission is established between the vehicle 10 and the station 12, advantageously initially in a limited form (as shown in block 44) and then without restriction (as shown in block 46). The end of the restriction of the power transmission in the limited form is determined by a test 48. The information exchange between the drive module 24 of the station 12 and the control module 22 of the vehicle 10 remains established during the power transmission shown in blocks 44 and 46.

Claims

1. A station intended to exchange electric power with an electric vehicle (10), the station (12) comprising a power converter (18) and a drive module (24) for driving the power converter (18), the drive module (24) intended to communicate with a control module (22) of the vehicle (10) via a cable (20), characterized in that The station (12) further comprises means (S6) for receiving a voltage originating from a low-voltage power source (34) of the vehicle (10) via the cable (20) to power the drive module (24), and a voltage source (32) capable of generating a signal intended for a control module (22) of the vehicle (10) via an impedance (Rpb) of the station (12), the cable (20) and an impedance (Rpv) of the vehicle (10) that can be short-circuited by a switch (S4) of the vehicle (10).

2. The station according to claim 1, wherein The means for receiving a supply voltage comprises a switch (S5) allowing the voltage source (32) to be disconnected.

3. An electric vehicle intended to exchange electric power with a station (12), the vehicle (10) comprising a control module (22) intended to communicate via a cable (20) with a drive module (24) to drive the power converter (18) of the station (12), characterized in that The vehicle (10) further comprises a low-voltage power supply (34), connection means (S3) for connecting the low-voltage power supply (34) to the cable (20) to supply power to the drive module (24) of the station (12), and an impedance (Rpv) having a value substantially the same as the impedance (Rpb) of the station (12), through which the drive module (24) of the station (12) can be supplied by the voltage source (32) of the station (12), the impedance (Rpv) of the vehicle (10) being arranged between the control module (22) and the cable (20); the vehicle comprises a switch (S4) allowing the impedance (Rpv) of the vehicle (10) to be short-circuited.

4. A vehicle according to claim 3, intended to exchange electric power with a station (12) according to claim 1 or 2, and characterized in that The vehicle (10) further includes temporary means for limiting the power transferred between the vehicle and the station (12).

5. A method for exchanging electric power between a vehicle (10) as claimed in claim 3 or 4 and a station (12) as claimed in claim 1, characterized in that This method involves connecting the following operations: supplying power (40) to the drive module (24) of the station (12) via the low voltage power supply (34) of the vehicle (10), Initiating data exchange (42) via the cable (20) to drive the power converter (18) to receive power from the vehicle (10), Electric power is transmitted from the vehicle (10) to the station (12).

6. A method for transmitting electric power from a vehicle (10) as claimed in claim 3 to a station, wherein The method comprises the following two consecutive steps: a step of precharging with a limited current as long as the voltage difference between the battery (14) and the power converter (18) is greater than a given value, Once the voltage difference between the battery (14) and the power converter (18) is less than or equal to the given value, the step of transmitting power without current limitation is performed.

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