Method for operating a bidirectional charger, bidirectional charger, control device and system for bidirectional energy transmission

Abstract

The invention relates to a bidirectional charger, in particular a bidirectional charger in an electric vehicle, for feeding electrical energy from the electric vehicle into an energy supply network. A bidirectional charger can monitor electrical parameters during the feeding of electrical energy into the energy supply network and, in the event of a deviation of the electrical parameters, transmit an error signal to an external component such as a charging point connected to the electric vehicle. The charging point and the charger can thus be synchronised with one another.

Description

[0001] Description

[0002] title

[0003] Method for operating a bidirectional charger, bidirectional charger, control device and system for bidirectional energy transfer

[0004] Technical area

[0005] The present invention relates to a method for operating a bidirectional charger, in particular a bidirectional charger for an electric vehicle. The present invention further relates to a bidirectional charger, a control device, and a system for bidirectional energy transfer.

[0006] State of the art

[0007] Fully or at least partially electrically powered vehicles comprise an electric drive system that can be supplied with electrical energy from an electrical energy storage device, such as a traction battery. The electrical energy storage device of such a vehicle can be charged from an external energy source when the vehicle is stationary. Among other things, charging concepts exist for this purpose in which the electric vehicle can be connected to a single- or multi-phase electrical power supply network, and the alternating voltage provided by this power supply network can then be rectified by a charger integrated into the vehicle and adjusted to a voltage level suitable for charging the electrical energy storage device.

[0008] For example, the publication DE 10 2022 201 132 A1 describes a charger for an electrically powered vehicle and a method for operating a charger for an electrically powered vehicle. The charger described therein has an input-side AC voltage connection for connecting an AC voltage source and an output-side high-voltage DC voltage connection for connecting a battery to be charged.

[0009] Furthermore, initial concepts already exist for expanding a charger in an electric vehicle to enable reverse energy transfer from the electrical energy storage device to the charger's AC voltage connection. Such chargers are referred to below as bidirectional chargers. If such a bidirectional charger is to be connected to a power grid to feed electrical energy into the power grid, existing regulations and standards must be observed. In particular, it must be ensured that reliable galvanic isolation between the charger and the power grid is guaranteed in the event of a fault or error on the grid side.

[0010] Disclosure of the invention

[0011] The present invention provides a method for operating a bidirectional charger, a bidirectional charger, a control device for a bidirectional charging process, and a system for bidirectional energy transfer with the features of the independent patent claims. Further advantageous embodiments are the subject of the dependent patent claims.

[0012] Accordingly, it is provided:

[0013] A method for operating a bidirectional charger. The bidirectional charger is configured to transfer electrical energy from a DC voltage connection to an AC voltage connection in a first operating mode. Furthermore, the bidirectional charger is configured to transfer electrical energy from the AC voltage connection to the DC voltage connection in a second operating mode. The method comprises a step of monitoring at least one electrical measured value during the transfer of electrical energy from the DC voltage connection to the AC voltage connection. Furthermore, the method comprises a step of signaling an error signal. The error signal can be signaled in particular via a communication line between the bidirectional charger and a charging point.The charging point is a charging point that is electrically connected to the AC power supply for energy transmission. The error signal is generated in particular if at least one monitored measured value falls outside a specified range.

[0014] Furthermore, it is planned:

[0015] A bidirectional charger with an AC voltage connection, a DC voltage connection, a voltage converter arrangement, a control device, and a communication device. The AC voltage connection is designed to be electrically coupled to a charging point. The DC voltage connection is designed to be electrically coupled to an electrical energy storage device. The voltage converter arrangement is designed to transfer electrical energy from the DC voltage connection to the AC voltage connection in a first operating mode. The voltage converter arrangement is further designed to transfer electrical energy from the AC voltage connection to the DC voltage connection in a second operating mode. The control device is designed to monitor at least one electrical measured value during the transfer of electrical energy from the DC voltage connection to the AC voltage connection.Furthermore, the control device is designed to detect an error. In particular, an error can be detected if at least one monitored measured value lies outside a predetermined value range. The communication device is designed to output an error signal. In particular, the communication device can signal an error signal via a communication line between the bidirectional charger and the charging point. The communication device can, in particular, signal the error signal if the control device has detected an error when monitoring the at least one electrical measured value.

[0016] Furthermore, it is planned:

[0017] A control device for a bidirectional charging process. The control device comprises a communication device. This communication device is designed to be coupled to a communication line of a bidirectional charger. The communication device can receive an error signal from the bidirectional charger via this communication line. The control device is designed to interrupt an electrical connection between a power grid and the bidirectional charger at a charging point if an error signal has been received from the bidirectional charger.

[0018] Finally, it is planned:

[0019] A system for bidirectional energy transfer between a charging point and an electric vehicle. The system comprises a bidirectional charger according to the invention, a control device according to the invention, and a charging point. The charging point is designed to be coupled to the power grid. Furthermore, the charging point is designed to be coupled to the bidirectional charger.

[0020] Advantages of the invention

[0021] Systems have now been established for charging electric vehicles in which electrical energy can be supplied from a power grid in the form of single-phase or multi-phase alternating voltage via a charging point on the electric vehicle. The electric vehicle has an integrated charger, also known as an on-board charger (OBC). This charger can convert the alternating voltage supplied by the power grid via the charging point into a direct voltage, which is suitable for charging a battery integrated in the electric vehicle. In addition, initial concepts already exist for feeding electrical energy from the electric vehicle's battery into a power grid via a charging point in the opposite direction. However, applicable regulations and standards must be taken into account here. These regulations and standards are part of the standardization process.Standards also include, in particular, specifications for grid and system protection, and in particular specifications for reliable separation between the energy supply grid and the electric vehicle in the event of a fault.

[0022] In this context, one idea of ​​the present invention is to at least partially utilize components within the electric vehicle, in particular components of the charger in the electric vehicle, for the separation between the power grid and the electric vehicle. Furthermore, components of the charger within the vehicle can also be used to detect possible malfunctions or errors and subsequently initiate a possible interruption of the electrical connection between the electric vehicle and the power grid.

[0023] For this purpose, the invention provides for a simple but reliable communication between the charger within the electric vehicle and a charging point coupled to this charger, via which possible errors or requests for an interruption of the electrical connection can be reliably signaled.

[0024] In this way, it is possible to coordinate the operations within the charging point and within the charger in the electric vehicle in the event of an interruption between the energy supply grid and the electric vehicle. For example, for a redundant interruption of the electrical connection between the energy supply grid and the electric vehicle, both an interruption within the charging point and an interruption within the bidirectional charger can be provided. In this way, for example, conventional charging points, which generally only have one switching component per electrical phase, can be combined with an additional interruption within the bidirectional charger in order to create a double and therefore redundant interruption. This also makes it possible to use conventional charging points with or without acan only be used with minor modifications to feed electrical energy into an energy supply network.

[0025] Furthermore, by monitoring electrical parameters such as voltage, frequency, current, etc. within the charger, components already present in the electric vehicle can be utilized. This may eliminate the need for additional components, resulting in savings in installation space and costs.

[0026] Furthermore, the communication connection between the bidirectional charger and the charging point can also be used to transmit external signals, such as a limitation of the electrical power fed in or a request to interrupt the feed-in of electrical energy into the energy supply grid, from the charging point to the electric vehicle and in particular to the bidirectional charger.

[0027] If the feed-in of electrical energy into the power grid is interrupted, the feed-in can then be restarted – if necessary after the cause of the interruption has been eliminated. To do this, the bidirectional charger can first check whether the requirements for feeding electrical energy back into the grid are met. For example, voltage conditions within the bidirectional charger can be checked. However, other criteria for the requirements for feeding electrical energy into the power grid can also be checked. The bidirectional charger can then signal to the charging point via the communication line that it is ready to supply electrical energy again.If the requirements for feeding electrical energy into the power grid are also met at the charging point, the electrical voltage from the power grid can be released through the charging point, so that this electrical voltage is applied to the bidirectional charger. Meanwhile, the bidirectional charger monitors the electrical parameters, such as the electrical voltage at the AC connection. In particular, electrical parameters are monitored upstream of an electrical isolation unit within the bidirectional charger. If the bidirectional charger determines that the monitored parameters are within a value range for which the feeding of electrical energy is permitted, an electrical connection can be established by the isolation unit within the bidirectional charger.The bidirectional charger can then transfer electrical energy to the charging point and further into the energy supply grid.

[0028] According to one embodiment, signaling the error signal from the bidirectional charger to the charging point via the communication line involves interrupting the communication line between the bidirectional charger and the charging point. With such a concept, the transmission of electrical energy from the electric vehicle to the power grid is only enabled if an electrical connection is established via the communication line. This also allows for faults, and in particular interruptions in the cable connection between the charging point and the charger, to be taken into account, thereby further increasing the safety of the overall system.

[0029] According to one embodiment, the communication line comprises a Control Pilot (CP) line between the bidirectional charger and the charging point. Such a communication line is already provided for in existing standards, for example, to coordinate the charging power when charging the battery in the electric vehicle with the charging point. In particular, such a line can be used, for example, to signal the maximum available charging power from the charging point.

[0030] According to one embodiment, the error signal can be signaled using powerline communication. Existing communication channels for data exchange between the charging point and the bidirectional charger can also be used to exchange the error signal.

[0031] According to one embodiment, the method further comprises a step of interrupting the transmission of electrical energy from the DC voltage connection to the AC voltage connection in the bidirectional charger. The interruption of the transmission of electrical energy can occur, in particular, if at least one monitored measured value lies outside a predetermined value range. In this way, for example, an electrical interruption can be performed by the charger, and additionally, a further interruption can be performed within the charging point by signaling via the communication line. This allows a redundant or two-stage interruption to be implemented by the components present in the charging point and the charger.

[0032] According to one embodiment, the method further comprises a step for receiving a signal from the charging point. This signal can also be transmitted via the communication line, which is also used to signal the error signal. The method can then further comprise a step for interrupting the transmission of electrical energy from the DC voltage connection to the AC voltage connection in the bidirectional charger if such a signal has been received. In this way, it is possible to use the components of the bidirectional charger to interrupt or disconnect the electric vehicle from the grid connection, even if the request for this was generated by an external component. For example, such a request can be generated within the charging point or transmitted by an external entity, such as the operator of the energy supply grid.

[0033] According to one embodiment of the bidirectional charger, the communication device of the bidirectional charger is configured to receive a signal from the charging point. The control device can be configured to interrupt the transmission of electrical energy from the DC voltage connection to the AC voltage connection in the bidirectional charger if such a signal has been received from the charging point.

[0034] According to one embodiment, the communication device of the control device for a bidirectional charging process may be designed to output a signal to the bidirectional charger in order to cause the bidirectional charger to interrupt an electrical connection between the charging point and the bidirectional charger.

[0035] According to one embodiment, the control device in the system for bidirectional energy transfer between a charging point and an electric vehicle can be integrated in the charging point.

[0036] In an alternative embodiment, the control device can be provided as a separate component outside the charging point. Such a separate component can be added to an existing, particularly conventional, charging point, for example, in the form of an adapter or the like.

[0037] The above embodiments and further developments can be combined with each other as desired, where appropriate. Further embodiments, further developments, and implementations of the invention also include combinations of features of the invention not explicitly mentioned above or described below with regard to the exemplary embodiments. In particular, those skilled in the art will also add individual aspects as improvements or additions to the respective basic forms of the invention.

[0038] Short description of the drawings

[0039] Further features and advantages of the invention are explained below with reference to the figures.

[0040] Fig. 1: a schematic diagram illustrating a bidirectional charging process according to an embodiment;

[0041] Fig. 2: a schematic representation of a system for bidirectional energy transfer according to an embodiment;

[0042] Fig. 3: a schematic representation of a basic circuit diagram for communication between charging point and bidirectional charger according to an embodiment;

[0043] Fig. 4: a schematic representation of a charging point for a system for bidirectional energy transfer according to another embodiment; and

[0044] Fig. 5: a schematic representation of a method for operating a bidirectional charger as may be the basis of an embodiment.

[0045] Description of embodiments

[0046] Figure 1 shows a schematic representation of a principle diagram of an electric vehicle 3 with a bidirectional charger 1, which is electrically coupled to a power supply network 5 via a charging point 4. To charge an electrical energy storage device 2 in the electric vehicle 3, the power supply network 5 can, for example, provide electrical energy, which is thus made available at the charging point 4, for example a wall box or the like. This charging point 4 can also be referred to as Electrical Vehicle Supply Equipment (EVSE). The electric vehicle 3, in particular the charger 1, can be electrically connected to this charging point 4 by means of a suitable cable connection. Thus, a single- or multi-phase electrical alternating voltage from the power supply network 5 is applied to an alternating voltage connection of the charger 1.This alternating voltage can be converted into a direct voltage by means of the charger 1, which is suitable for charging the electrical energy storage device 3.

[0047] In a further operating mode, the charger 1 can convert electrical energy from the electrical energy storage device 2 into a single-phase or multi-phase alternating voltage and provide it at the connection to the charging point 4. This alternating voltage can thus be fed into the energy supply network 5 via the charging point 4.

[0048] Figure 2 shows a schematic representation of a principle diagram for a system for bidirectional energy transfer between a charging point 4 and an electric vehicle 3 according to one embodiment. To simplify the illustration, only a single-phase connection for the AC voltage network was shown in Figure 2. However, it is understood that the present invention is not limited to this. Rather, the inventive concept can also be applied to multiple phases, in particular three phases, of an electrical power supply network.

[0049] The system for bidirectional energy transfer comprises a bidirectional charger 1 and a charging point 4 with a control device 40. As will be explained in more detail below, the control device 40 can be integrated within the charging point 4 or, alternatively, can be provided as an additional component outside the charging point 4. The charging point 4 can, on the one hand, be coupled to an energy supply network 5, in particular a single-phase or multi-phase electrical energy supply network 5. Furthermore, the charging point 4 can be electrically connected to an electric vehicle 3, in particular a bidirectional charger 1, via a suitable electrical connection, in particular a suitable cable connection. The connection between the charging point 4 and the charger 1 includes not only the lines for electrical energy transfer but also a communication connection.This communication connection can be implemented, for example, via one or more electrical lines. For this purpose, a charging cable connecting charging point 4 to charger 1 can, for example, contain one or more additional communication lines in addition to the power transmission lines. However, it is also possible, in principle, to implement the communication connection, for example, via powerline communication or another suitable communication technology.

[0050] The charger 1 comprises an AC voltage connection 11. The charger 1 can be connected to the charging point 4 via this AC voltage connection 11. The AC voltage connection 11 can, for example, comprise suitable contacts for connecting the power transmission lines. Furthermore, the AC voltage connection 11 can also comprise one or more contacts for coupling the communication lines.

[0051] The charger 1 further comprises a DC voltage connection 12. An electrical energy storage device 2, such as the traction battery of an electric vehicle, can be connected to this DC voltage connection 12. A voltage converter arrangement 15 is provided between the AC voltage connection 11 and the DC voltage connection 12. In one operating mode, this voltage converter arrangement 15 can convert the electrical AC voltage provided at the AC voltage connection 11 into a DC voltage suitable for charging an electrical energy storage device 2 connected to the DC voltage connection 12. In a further operating mode, the voltage converter arrangement 15 can convert electrical energy from an electrical energy storage device 2 connected to the DC voltage connection 12 into a single-phase or multi-phase AC voltage and provide this AC voltage at the AC voltage connection 11.However, since the basic principle of such a voltage converter arrangement 15 can be assumed to be known, a more detailed description is omitted here.

[0052] Sensors or measuring components such as voltage sensors 16 and / or current sensors 17 can be provided between the AC voltage connection 11 and the voltage converter arrangement 15. In addition, however, any other measuring elements or sensors are also possible in principle. In this way, an electrical voltage at the AC voltage connection 11 can be monitored and, if necessary, the energy transfer between the AC voltage connection 11 and the voltage converter arrangement 15 can also be monitored. For such monitoring, for example, a control device 18 in the charger 1 can receive measured values ​​and compare them with predetermined limit values. If necessary, further parameters can also be derived from the measured values ​​and these derived parameters can be compared with predetermined limit values. If a deviation from the measured values ​​orparameters derived from it, this can be interpreted as an indication of a fault or error.

[0053] If such an error or malfunction is detected, the control device 18 can initiate the necessary measures, for example, within the bidirectional charger 1. For example, a power transfer, in particular a power transfer from the DC voltage connection 12 to the AC voltage connection 11, can be stopped. Furthermore, an electrical connection between the AC voltage connection 11 and the DC voltage connection 12 can be interrupted. For this purpose, for example, semiconductor switching elements within the voltage converter arrangement 15 can be opened.

[0054] Furthermore, in the event of a malfunction or error, an error signal can be output by a communication device 19. In particular, such an error signal can be output to the charging point 4. For this purpose, the error signal can be signaled via a communication line between the bidirectional charger 1 and the charging point 4. For example, to signal an error, a switching element within the communication device 19 can be opened to interrupt the corresponding communication line.

[0055] The signaling of the error signal can be received or detected in the charging point 4 by a suitable control device 40, in particular a communication device 41 in the control device 40. The control device 40 of the charging point 4 can then, for example, initiate an interruption of the electrical connection for the energy transmission from the charger 1. For this purpose, suitable switching elements, in particular mechanical switching elements, can be opened in the charging point 4. In this way, the energy supply network 5 is separated from the electrical energy storage device 2 in the electric vehicle, on the one hand, by the switching elements in the charging point 4 and, furthermore, by the interruption in the bidirectional charger 1.

[0056] Furthermore, it is also possible, for example, for the control device 40 and in particular the communication device 41 of the charging point 4 to transmit a signal to the bidirectional charger 1 and in particular to the communication device 19 of the bidirectional charger 1. Subsequently, an interruption of the electrical connection between the AC voltage connection 11 and the DC voltage connection 12 can also be initiated in the bidirectional charger 1, for example, based on such a signal. In principle, however, it is also possible for the control device 40 and in particular the communication device 41 to transmit any other information to the bidirectional charger 1 via this communication line.The bidirectional charger 1 and in particular the control device 18 provided therein can then evaluate this information in order to initiate suitable measures if necessary, such as interrupting the electrical connection between the AC voltage connection 11 and the DC voltage connection 12.

[0057] Figure 3 shows a schematic representation of a possible embodiment for communication between the communication device 19 in the bidirectional charger 1 and the communication device 41 in the control device 40 of the charging point 4. For example, various electrical resistors R1, R2 can be provided in the communication device 19 in the bidirectional charger 1, which can be connected by switching elements M1, M2 into an electrical circuit between the communication device 41 of the control device 40 and the communication device 19 of the charger 1. In this way, the communication device 41 can, based on the respectively determined electrical resistance in this circuit, draw conclusions about the switching states of the switching elements M1, M2 in the communication device 19 and derive the states or information to be signaled therefrom.For example, by opening the switching element M1, the circuit can be completely interrupted. This can be considered, for example, as a signal for an interruption in the power transmission. Of course, any other signaling concepts are also possible. For example, the described communication can take place via existing communication lines such as ground (GND) and a Control Pilot (CP) line. However, depending on the charging standard or the connection between charging point 4 and charger 1, any other concepts are possible.

[0058] Figure 4 shows a schematic representation of a charging point 4 with a control device 40 for a system for bidirectional energy transfer according to one embodiment. This embodiment differs from the previously described embodiments in particular in that in this embodiment the control device 40 is provided outside the charging point 4. Furthermore, however, all statements already made in connection with the previously described embodiments apply. For the implementation shown in Figure 4, the control device 40 can, for example, be provided as an additional component between the charging point 4 and the charger 1. For example, the control device 40 can be attached to the charging point 4 in the form of an adapter or the like. In this way, for example, existing, conventional charging points can be very easily expanded for bidirectional energy transfer.

[0059] Finally, Figure 5 shows a flowchart underlying a method for operating a bidirectional charger 1 according to one embodiment. The method can, in principle, comprise any steps as previously described in connection with the bidirectional charger 1 and the corresponding system with such a bidirectional charger 1. Analogously, the previously described embodiments can also comprise any components or units that may be required to implement the method described below.

[0060] The method comprises a step S1 for monitoring at least one electrical measured value during the transmission of electrical energy from the DC voltage connection 12 to the AC voltage connection 11 of the bidirectional charger 1. Furthermore, the method comprises a step S2 for signaling an error signal. The error signal can be signaled, in particular, via a communication line between the bidirectional charger 1 and the charging point 4. The error signal is signaled, in particular, if at least one monitored measured value lies outside a predetermined value range.

[0061] Optionally, an interruption of the electrical connection between the DC voltage terminal 12 and the AC voltage terminal 11 can be carried out before, after or parallel to the signaling of the error signal in the bidirectional charger 1.

[0062] Furthermore, it is also possible to receive a signal from the charging point 4 and then interrupt the electrical connection between the AC voltage connection 11 and the DC voltage connection 12 if such a signal has been received from the charging point 4.

[0063] In summary, the present invention relates to the operation of a bidirectional charger, in particular a bidirectional charger in an electric vehicle, for feeding electrical energy from the electric vehicle into a power grid. A bidirectional charger can monitor electrical parameters while feeding electrical energy into the power grid and, in the event of a deviation in the electrical parameters, transmit an error signal to an external component, such as a charging point connected to the electric vehicle. Thus, the charging point and charger can be synchronized with each other. In this way, existing components in the charging point and the charger can be used to meet the requirements for feeding electrical energy into a power grid.

Claims

Claims 1. A method for operating a bidirectional charger (1) which is designed to transmit electrical energy from a DC voltage connection (12) to an AC voltage connection (11) in a first operating mode and to transmit electrical energy from the AC voltage connection (11) to the DC voltage connection (12) in a second operating mode, the method comprising: Monitoring (S1) at least one electrical measured value during the transmission of electrical energy from the DC voltage connection (12) to the AC voltage connection (11); Signaling (S2) an error signal via a communication line between the bidirectional charger (1) and a charging point (4) which is electrically coupled to the AC voltage connection (11) if at least one monitored measured value lies outside a predetermined value range.

2. The method according to claim 1, wherein signaling (S2) of the error signal comprises interrupting the communication line between the bidirectional charger (1) and a charging point (4).

3. The method according to claim 1 or 2, wherein the communication line comprises a control pilot line between the bidirectional charger (1) and the charging point (4).

4. The method according to claim 1, wherein the signaling (S2) of the error signal is carried out by means of power line communication.

5. Method according to one of claims 1 to 4, comprising a step of interrupting the transmission of electrical energy from the DC voltage terminal (12) to the AC voltage terminal (11) in the bidirectional charger (1) if at least one monitored measured value lies outside a predetermined value range.

6. Method according to one of claims 1 to 5, comprising the steps Receiving a signal from the charging point (4); and Interrupting the transmission of electrical energy from the DC voltage connection (12) to the AC voltage connection (11) in the bidirectional charger (1) if a signal has been received.

7. A bidirectional charger (1), comprising: an AC voltage connection (11) designed to be electrically coupled to a charging point (4); a DC voltage connection (12) designed to be electrically coupled to an electrical energy store (2); a voltage converter arrangement (15) designed to transfer electrical energy from the DC voltage connection (12) to the AC voltage connection (11) in a first operating mode and to transfer electrical energy from the AC voltage connection (11) to the DC voltage connection (12) in a second operating mode; a control device (18) designed to monitor at least one electrical measured value during a transfer of electrical energy from the DC voltage connection (12) to the AC voltage connection (11), and to detect an error if at least one monitored measured value lies outside a predetermined value range; and a communication device (19) designed to signal an error signal via a communication line between the bidirectional charger (1) and a charging point (4) if an error has been detected.

8. The bidirectional charger (1) according to claim 7, wherein the communication device (19) is configured to receive a signal from the charging point (4); and wherein the control device (18) is configured to interrupt the transmission of electrical energy from the DC voltage connection (12) to the AC voltage connection (11) in the bidirectional charger (1) if a signal has been received from the charging point (4).

9. Control device (40) for a bidirectional charging process, comprising a communication device (41) which is designed to be coupled to a bidirectional charger (1) by means of a communication line, and wherein the control device (40) is designed to interrupt an electrical connection between a power supply network (5) and the bidirectional charger (1) in a charging point (4) if an error signal has been received from the bidirectional charger (1).

10. Control device (40) according to claim 9, wherein the communication device (41) is designed to output a signal to the bidirectional charger (1) to cause the bidirectional charger (1) to interrupt an electrical connection between the charging point (4) and the bidirectional charger (1).

11. A system for bidirectional energy transfer between a charging point (4) and an electric vehicle (3), comprising: a bidirectional charger according to claim 8; a charging point (4) configured to be coupled to a power grid (5) and the bidirectional charger (1), and a control device (40) according to claim 9 or 10.

12. System according to claim 11, wherein the control device (40) is integrated in the charging point (4).

13. System according to claim 11, wherein the control device (40) is provided as a separate component outside the charging point (4).

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