Method for operating a charging system for charging an electric vehicle and charging system

Abstract

Method for operating a charging system (10) for charging an electric vehicle (1), wherein a grid partial power is provided from a supply network (2) connected to the charging system (10) and a storage partial power is provided from an energy storage device (11.1) of the charging system (10), characterized in that the storage partial power is set such that the storage partial power includes higher frequency components than the grid partial power determined by a current measurement, a time average of the grid partial power, which is formed over a predetermined time interval which is less than or equal to 20 minutes, does not exceed a predetermined maximum average value, and a fuse temperature of a fuse of a grid connection (19) for the supply network (2), which is determined by the current measurement, does not exceed a predetermined maximum temperature value.

Description

[0001] The invention relates to a method for operating a charging system for charging an electric vehicle, wherein a partial grid power is provided from a supply network connected to the charging system and a partial storage power is provided from an energy storage device of the charging system. Furthermore, the invention relates to a charging system for charging an electric vehicle with a grid connection for providing a partial grid power from a supply network and with an energy storage device for providing a partial storage power from an energy storage device.

[0002] Charging systems for electric vehicles with an externally chargeable battery, such as battery-electric vehicles or plug-in hybrid vehicles, are often designed to provide a consistently high electrical power supply from the grid for charging the electric vehicle. However, there are also charging systems that only rarely require their peak power output, making it economically unviable to maintain a high grid connection capacity for these systems. These latter charging systems typically include an energy storage unit, which can provide a portion of the power from the storage unit as needed, in addition to the partial power supplied by the grid.

[0003] Methods for operating such charging systems are known in the prior art, in which the storage partial power is controlled by a control unit. The known control units are typically designed as programmable logic controllers (PLCs) and react sluggishly to changes in load or power. This can lead to an undesirable exceedance of a maximum permissible partial load on the grid over a longer period and / or to the tripping of a circuit breaker in the power grid.

[0004] Against this background, the task arises to avoid overload situations with an increased probability when operating a charging system mentioned at the beginning.

[0005] To solve the problem, a method for operating a charging system for charging an electric vehicle is proposed, wherein a grid partial power is provided from a supply network connected to the charging system and a storage partial power is provided from an energy storage device of the charging system, wherein the storage partial power is set such that the storage partial power includes higher frequency components than the grid partial power.

[0006] In the method according to the invention, short-term peak power is provided as storage partial power from the energy storage of the charging system. The energy storage is preferably located externally to the vehicle. The storage partial power provided from the energy storage of the charging system exhibits higher dynamics and thus higher frequency components than the grid partial power. In this way, the grid partial power can be kept either constant and / or below a predetermined setpoint.

[0007] According to an advantageous embodiment of the invention, the grid power is detected by a power measurement and / or determined by a current measurement. The detected or determined grid power is preferably used to adjust the storage power. The charging system can include a power measuring device to detect the grid power. Alternatively, the charging system can include a current measuring device, the measurement of which determines the grid power.

[0008] An advantageous embodiment provides that the storage power output is adjusted by means of a control device, in particular a controller, which includes a high-pass filter, especially a first-order high-pass filter, and / or a band-pass filter. The high-pass filter can attenuate low-frequency components, allowing the controller to transmit a high-frequency power or current request to the energy storage device of the charging system. The use of a band-pass filter offers the advantage that, in addition to attenuating low-frequency components, unwanted high-frequency noise can also be eliminated.

[0009] According to an advantageous embodiment, the storage partial power is adjusted such that the time-averaged value of the grid partial power does not exceed a predetermined maximum average value. By adjusting, and in particular regulating, the grid partial power can briefly exceed a predetermined setpoint value, while ensuring that the predetermined maximum average value is not exceeded over a predetermined period during which the time average is calculated. This approach can be advantageous, for example, when consumption is measured based on predetermined time intervals, for each of which the time-averaged value of the grid partial power is recorded. Therefore, it is preferable that the period over which the time average is calculated is chosen to be less than or equal to the time interval used for consumption measurement.This allows the time-based average of the network partial power, which is relevant for consumption recording, or the energy costs, to be kept as low as possible.

[0010] In this context, it is advantageous if the time average of the network partial power is calculated over a predetermined time interval, which is in the range of less than or equal to 20 minutes, preferably less than or equal to 15 minutes.

[0011] Alternatively or additionally, it may be provided that the time average is calculated using an averaging filter, in particular a moving average filter.

[0012] A preferred embodiment provides that the safety temperature of a fuse, in particular a cartridge fuse, of a network connection to the supply network does not exceed a predetermined maximum temperature value. This ensures that the network's partial power can briefly exceed a setpoint without the risk of the fuse tripping.

[0013] In this context, it has proven advantageous to monitor the fuse temperature and / or determine it by measuring the current. The fuse temperature can be measured using a temperature sensor. Alternatively or additionally, it can be determined by measuring the current. The following relationship applies to the fuse temperature: C w d T ( t ) d t = R I 2 − g ( T ( t ) − T a m b i e n t ) with the target T ( t ) < T f u s e where C wthe heat capacity of the fuse, I the mains current, R the resistance of the fuse, g a measure of heat conduction to the environment, T ambient the ambient temperature, T(t) the fuse temperature, t the time and T fuse The temperature at which the fuse trips is the one at which the fuse trips. This differential equation is preferably solved to determine the fuse temperature.

[0014] Alternatively or additionally, the safety temperature can be determined using a forward Euler method. The aforementioned differential equation can be solved with relatively little effort using the forward Euler method.

[0015] An advantageous embodiment of the invention provides that the energy storage device is an electrical energy storage device, in particular a battery, accumulator, capacitor or supercapacitor, or a mechanical energy storage device, in particular a flywheel energy storage device. The energy storage device of the charging system is preferably stationary and advantageously connected to a charging port and / or a charging station of the charging system, via which an electric vehicle can be connected to the charging system.

[0016] Another object of the invention is a charging system for charging an electric vehicle with a grid connection for providing a partial grid power from a supply network and with an energy storage device for providing a partial storage power from an energy storage device, wherein the charging system includes a control device that is configured to adjust the partial storage power in such a way that the partial storage power includes higher frequency components than the partial grid power.

[0017] The same advantages can be achieved with the charging system as have already been described in connection with the inventive method for operating a charging system.

[0018] According to an advantageous embodiment of the charging system, the control unit is configured to adjust the storage partial power output in such a way that - a time-averaged value of the network partial power does not exceed a predetermined maximum average value; and / or - the fuse temperature of a fuse of a network connection for the supply network does not exceed a specified maximum temperature value.

[0019] This allows for a brief exceedance of a predetermined target value for the network partial power and also ensures that, on average over a predetermined time interval, an excessively high network partial power is not required or that a network connection protection is not triggered.

[0020] Further advantages and details of the invention will be explained below with reference to the exemplary embodiments illustrated in the drawings. These represent only preferred embodiments of the invention and do not limit it. Herein is shown: Fig. 1 a schematic block diagram of a charging system according to a first embodiment of the invention; Fig. 2 a schematic block diagram of a charging system according to a second embodiment of the invention; and Fig. 3 a schematic block diagram of a charging system according to a third embodiment of the invention.

[0021] In the Fig. 1 is a first embodiment of a charging system 10 for charging an electric vehicle 1 with a network connection 19 to provide a partial network service from a supply network 2 and with an energy storage device 11 to provide a partial storage capacity from an energy storage device 11 The charging system 10 It also includes a control unit 13 to control the power output by the energy storage device 11 .

[0022] The energy storage of the energy storage device 11 of the charging system 10 It is designed as an electrical energy storage device, for example as a battery, accumulator, capacitor, or supercapacitor. Alternatively, the energy storage device can be a mechanical energy storage device, in particular a flywheel energy storage device. In the present embodiment, the energy storage device is 11 by means of a transformer 14 with the supply network 2 or with a charging system network 3 of the charging system 10 connected. This creates galvanic isolation of the energy storage device. 11 from the supply network 2 or the charging system network 3 reached.

[0023] The charging system 10 It also includes a charging port 16 about an electric vehicle 1 with the charging system 10can be connected. In the representation according to Fig. 1 is an electric vehicle 1 using a charging cable 17 with the charging port 16 of the charging system 10 tied together.

[0024] Another component of the charging system 10 According to the first embodiment, a photovoltaic system 12 , which are connected to the charging system network 3 is connected. The photovoltaic system comprises solar cells. 12.2 , which are equipped with an inverter 12.1 are connected, so that by means of the inverter 12.1 A partial photovoltaic power output can be provided, which, in addition to the grid power output and the storage power output, can be used to charge the electric vehicle. 1 can be used.

[0025] To determine the partial power output of the network, a current measuring device is also required. 15 , intended to be the one through the supply network 2The current measuring device measures the supplied electrical current. 15 is connected to the control unit 13 connected and provides the control unit 13 The result of the current measurement is available.

[0026] The network connection 19 It includes a fuse (not shown in the drawing), which is designed as a fusible link. In an overload situation, there is a risk that the fuse will trip and the power supply network will be interrupted. 2 from the charging system network 3 Disconnect. If the charging system is operated in an overload range for such a short time that the fuse does not yet trip, there is a risk of increased energy costs due to the temporarily increased power consumption. To avoid such overload situations during operation of the charging system as much as possible, the energy storage device 11 provided storage capacity via the control unit 13such that the storage power output includes higher frequency components than the mains power output. This adjustment is preferably achieved using a controller that includes a high-pass filter and / or a band-pass filter.

[0027] The representation in Fig. Figure 2 shows a second embodiment of a charging system 10 according to the invention with a mains connection designed as a transformer 19 to provide a partial network power from a multi-phase, here three-phase, supply network 2 and with an energy storage device 11 to provide partial storage power from an energy storage system 11.1 the energy storage device 11 The energy storage device 11 also includes one connected to the energy storage 11.1 connected inverter 11.2 , via which the energy storage 11.1 with the multi-phase, here three-phase, charging system network3 is connected.

[0028] Furthermore, the charging system includes 10 a control device 13 , which - as already mentioned above in connection with Fig. As mentioned in point 1, the storage power output is configured to include higher frequency components than the grid power output. The control unit 13 includes a d / q transformation device 20 to convert the signal from the current measuring device 15 The provided three-phase measurements are converted into a current amplitude value and a phase value as a function of time. The current amplitude value is then passed through a filter. 21 supplied, which is preferably designed as a high-pass filter or a band-pass filter. The signal passing through the filter 21 The filtered current amplitude value is fed to a current controller designed as a PL current control loop. 22supplied, which issues a current request. The current request is combined with the output from the d / q transformation unit. 20 obtained phase value of an inverse d / q transformation device 23 supplied. The inverse d / q transformation device 23 generates three-phase control variables that are used by a modulator 24 The modulator generates control signals for the power electronics. 11.2 the energy storage unit 11 This couples the energy storage unit. 11.1 to the charging system network 3 .

[0029] The representation in Fig. Figure 3 shows a third embodiment of a charging system according to the invention. The third embodiment corresponds essentially to the second embodiment, with the difference that the d / q transformation device 20 obtained current amplitude value and phase value, additionally also a reactive current compensation device25 to be supplied. In this reactive power compensation device 25 Reactive currents are compensated by the control objective of a predetermined advance angle.

[0030] The charging systems described above can be operated using a method in which a grid power component is provided from a supply network connected to the charging system and a storage power component is provided from an energy storage device of the charging system, and in which the storage power component is set such that the storage power component includes higher frequency components than the grid power component.

[0031] For example, the storage power output can be adjusted so that the time-averaged value of the grid power output does not exceed a predefined maximum average value. This time-averaged value of the grid power output can be calculated over a predefined time interval, which is less than or equal to a certain value. 20 The time interval is 15 minutes, preferably less than or equal to 15 minutes. The control unit can be used to calculate the time average. 13 include an averaging filter, for example a moving average filter.

[0032] Alternatively or additionally, the storage partial power can be set so that a fuse temperature of the mains connection fuse is maintained. 19 does not exceed a predetermined maximum temperature value. For this purpose, it is advantageous if the fuse temperature is recorded and / or determined by measuring the current of the current measuring device. 15is determined. For example, the fuse temperature can be determined using an Euler forward method based on current measurement.

Claims

[1] Method for operating a charging system (10) for charging an electric vehicle (1), wherein a grid power is provided from a supply network (2) connected to the charging system (10) and a storage power is provided from an energy storage device (11.1) of the charging system (10), characterized by , that the storage power output is set in such a way that the storage power output includes higher frequency components than the grid power output. [2] Method according to claim 1, characterized by that the network partial power is recorded by a power measurement and / or determined by a current measurement. [3] Method according to any one of the preceding claims, characterized by , that the storage partial power is adjusted by means of a control device (13), in particular by means of a controller, which includes a high-pass filter (21) and / or a band-pass filter. [4] Method according to any one of the preceding claims, characterized by, that the storage partial power is set in such a way that a time average of the network partial power does not exceed a predetermined maximum average value. [5] Method according to claim 4, characterized by that the time average of the network partial power is calculated over a specified time interval, which is in the range of less than or equal to 20 minutes, preferably less than or equal to 15 minutes. [6] Method according to one of claims 4 or 5, characterized by , that the time average is formed using an averaging filter, in particular a moving average filter. [7] Method according to any one of the preceding claims, characterized by , that a fuse temperature of a fuse of a network connection (19) for the supply network (2) does not exceed a specified maximum temperature value. [8] Method according to claim 7, characterized bythat the fuse temperature is recorded and / or determined by means of a current measurement. [9] Method according to one of claims 7 or 8, characterized by that the fuse temperature is determined using an Euler forward method. [10] Method according to any one of the preceding claims, characterized by , that the energy storage device (11) is an electrical energy storage device, in particular a battery, accumulator, capacitor or supercapacitor, or a mechanical energy storage device, in particular a flywheel energy storage device. [11] Charging system (10) for charging an electric vehicle (1) with a grid connection (19) for providing a partial grid power from a supply network (2) and with an energy storage device (11) for providing a partial storage power from an energy storage device (11.1) of the energy storage device (11), characterized by, that the charging system (10) includes a control device (13) which is configured to adjust the storage partial power such that the storage partial power includes higher frequency components than the grid partial power. [12] Charging system according to claim 11, characterized by , that the control unit (13) is configured to adjust the storage partial power in such a way as to - that the time-averaged value of the network partial power does not exceed a predetermined maximum average value; and / or - a fuse temperature of a fuse of a network connection (19) for the supply network (2) does not exceed a specified maximum temperature value.

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