Apparatus for testing a charging device for electric vehicles, and vehicle having such an apparatus

Abstract

A first aspect relates to an apparatus for testing a charging device for electric vehicles by measuring a predefined electrical measuring point, wherein each measuring point has a current setpoint value and a voltage setpoint value, comprising a connection terminal, a stepwise adjustable resistive load, a regenerative electronic load, a voltage measuring unit for measuring the terminal voltage and a current measuring unit for measuring a terminal current. A further aspect relates to a vehicle comprising such an apparatus.

Description

[0001] Device for testing a charging device for electric vehicles and vehicle with such a device

[0002] The present invention relates to a device for testing a charging device for electric vehicles according to claim 1.

[0003] The mobility transition also includes the increasing installation of charging infrastructure in public spaces, e.g., on streets and squares. This charging infrastructure or charging device must be regularly inspected. Currently, various types of charging devices exist from different manufacturers with different technical characteristics such as achievable maximum power, achievable maximum voltage, achievable minimum current at the maximum voltage, etc. While some charging devices achieve a maximum voltage of 800 V, for example, the maximum voltage for others is 900 V or 1000 V.

[0004] Charging devices that measure measured values ​​for commercial or official use (charging billing) must undergo a conformity assessment before being placed on the market and then regularly inspected, e.g., through calibration. This involves approaching various measuring or test points, i.e., a specific voltage and current are applied, held constant for a period of time, and then determining the deviations between the measured and billed energy quantities.

[0005] When testing charging devices, the minimum current value is typically set with the maximum voltage value. Another measurement point is typically the minimum voltage value with the maximum current value. Additional measurement points in the value range between minimum and maximum are tested, although the exact values ​​also depend on the charging device type. Furthermore, losses occur due to factors such as heating and cabling, which are often compensated within the charging device using calculated compensation factors. Depending on the compensation methods and ranges specified by the charging device manufacturers, various measurement points in each compensation range must be tested during testing.To test charging devices, the charging device must be connected to a load that behaves similarly to an actual charging electric vehicle, and communication with the charging device must be established in accordance with the charging process. The charging power must therefore be absorbed by a device while the charging device is being tested. In the laboratory, the charging power is absorbed by regenerative electronic loads, which in turn feed the charging power back into the power grid. This is often not possible with mobile charging devices, for example, on public roads and squares, because there is no access point to the local power grid.

[0006] Another alternative is the sole use of a resistive load, which, however, can only be used with charging devices that do not perform the standardized voltage tolerance test. Furthermore, only fixed voltage and current test points can be set, which are only sufficient for testing individual charging device types. A charging device expects the behavior of a vehicle battery, which permanently generates a nearly constant countervoltage. However, if the charging device does not yet supply a charging voltage or if the current is flexibly changed accordingly, the voltage does not remain constant. A constant countervoltage, such as that of an electric vehicle battery actually connected to the charging device, cannot be generated with a resistive load alone.To make matters worse, the resistors in the resistive load are switched using contactors to change the current, thus drawing large amounts of power across the resistors. When the resistors are switched using contactors in this way, the current required to maintain a constant voltage changes. However, a charging device exhibits brief sluggish behavior and therefore does not deliver the new target current immediately, meaning that the voltage at the resistive load either drops or becomes too high during this brief period. These larger voltage changes cause the charging device to abort the charging process, as these voltage changes normally occur when the car battery is no longer connected or when an error occurs during charging.Therefore, a testing device must not only generate the counter voltage corresponding to the battery, but also compensate for the power difference in the switching moments.

[0007] Alternative solutions using a resistive load in a mobile application involve large and heavy capacitor banks, which are heavy and require a truck or trailer for transport. Furthermore, each charging device type requires a different, suitable resistive load-capacitor bank combination, requiring a different test fixture for each charging device type. This leads to significant effort in testing charging devices.

[0008] The alternative solution, DE 102014 013 870 A1, describes a mobile testing system for a vehicle charging station with an electric vehicle, wherein the electric vehicle has a built-in measuring device for testing the charging station, as well as a method for testing such a charging station. Neither the mobile testing system nor the connected electric vehicle have the option of setting a current setpoint and a voltage setpoint required for the charging device test as a measuring point.

[0009] The alternative solution, DE 102018 131 354 A1, describes a device for testing an electric vehicle charging station with specific interfaces to control and communication systems. The device can be adapted to different mobility and performance requirements. Due to the specific interfaces, only a specific charging device type can be tested.

[0010] The alternative solution EP 3 410 140 A1 describes a device for loading an electrical power source while at least partially feeding the absorbed power into a power grid, and a method for testing a charging station for electric vehicles using such a device. Due to the feed-in into a power grid, the power consumption is fundamentally dependent on the presence of a grid connection.

[0011] The task is therefore to develop an improved device for testing a charging device for electric vehicles, which is independent of existing feed-in options to the power grid and can test different types of charging devices.

[0012] The object is solved by independent claim 1. The dependent claims specify advantageous embodiments.

[0013] The invention relates to a device for testing a charging device for electric vehicles by measuring from a predefined electrical measuring point, each measuring point having a current setpoint and a voltage setpoint. The device comprises a connection terminal for electrical connection to the charging device, a stepwise adjustable resistive load, the stepwise adjustable resistive load having a plurality of predefined resistors, each of which can be switched on by means of a contactor, so that the stepwise adjustable resistive load has a total resistance based on the switched-on resistors, so that an approximate current setpoint and an approximate voltage setpoint are set at the connection terminal, the stepwise adjustable resistive load being connected in parallel to the connection terminal.Furthermore, the device comprises a regenerative electronic load which is connected in parallel to the connection terminal and to the adjustable resistive load, wherein the regenerative electronic load comprises at least one rectifier, so that the regenerative electronic load provides a terminal voltage which drops across the connection terminal and / or absorbs or emits a power difference which results from the product of a current difference of the current setpoint value and the current setpoint approximate value with the voltage setpoint approximate value and / or from the product of a voltage difference of the voltage setpoint value and the voltage setpoint approximate value with the current setpoint approximate value, wherein the absorbed power difference is fed into an energy storage unit or the emitted power difference is taken from the energy storage unit.Furthermore, the device comprises a voltage measuring unit for measuring the terminal voltage and a current measuring unit for measuring a terminal current.

[0014] A charging device is a device suitable for charging the battery of an electric vehicle. An electric vehicle is a vehicle with an electric motor and a rechargeable battery. The electric vehicle can be, for example, an electric car, a hybrid car, an electric truck, an electric sprinter, an electric scooter, an electric motorcycle, an electric moped, an electric moped, an electric bicycle, and so on. This list is not exhaustive.

[0015] The charging device is tested using predefined electrical measurement points. Each measurement point has a current setpoint and a voltage setpoint. Multiplying the current and voltage values ​​yields the power value, and the energy value is derived from the power value integrated over time. The exact measurement points depend on the specific type of charging device.

[0016] Testing requires the device and charging device; no additional access point to the power grid is required. This means that testing can be performed without feeding back into the power grid. This means that testing can also be performed at public or semi-public charging facilities where there is no possibility of feeding into the power grid.

[0017] Testing or assessing the conformity of a charging device usually involves setting up several measuring points one after the other. At each measuring point, the voltage and current are measured for a short period of time. The energy quantities measured and billed by the charging device are then compared with the energy quantities measured by the device. The charging device must measure the energy quantities within a specified tolerance to pass the test. Preferably, the measurement is carried out in such a way that up to 1 kWh of energy is consumed by the charging device during the measurement of a measuring point.

[0018] The connection terminal is used for the electrical connection to the charging device. The connection terminal can, for example, be a power plug suitable for the voltage and current range of the charging device. The plug can, for example, be a CCS plug or a Type 2 plug. A terminal voltage and a terminal current are present at the connection terminal. The terminal voltage is measured using the voltage measuring unit. The terminal current is measured using the current measuring unit. The voltage measuring unit is, for example, connected in parallel to the connection terminal and the resistive load. The current measuring unit is, for example, connected in series to the connection terminal and the parallel connection of the resistive load and the electronic load. In particular, the current measuring unit measures a total current that flows through the parallel connection of the loads.Furthermore, a processing unit uses the current measuring unit and the voltage measuring unit to calculate the current power and the amount of energy transferred over a period of time.

[0019] The step-adjustable resistive load can be adjusted to correspond to different resistance values. The resistive load comprises a large number of resistors that can be connected in series or parallel, resulting in various total resistance values ​​of the resistive load. It is switched on via a contactor, as simple switches cannot withstand the high power values ​​of the charging device. The resistive load provides a resistance so that a current and voltage value is set at the connection terminal that is as close as possible to the set current and voltage values ​​of the respective measuring point. Advantageously, the step values ​​that can be set in the resistive load include resistance values ​​with which typical voltage and current values ​​for testing the most common charging device types can be set, or at least come as close as possible to these.Because the resistive load has multiple resistors, but the number of resistors is limited to a finite number, not every resistance value can be generated by combining the resistors in the resistive load.

[0020] In a non-limiting example, the resistive load has two resistors. One resistor has a resistance of 10 kiloohms and the other has a resistance of 30 kiloohms. Consequently, the resistors can be combined in series, resulting in a total resistance of 40 kiloohms, or the resistors can be connected in parallel, resulting in a resistance of 7.5 kiloohms. However, if, for example, a total resistance of 15 kiloohms is required, this is not possible with the resistive load alone. The total resistance can only be approximated by the 10 kiloohm resistor. The difference in resistance between the resistance of the resistive load and the target resistance is compensated for by the regenerative electronic load, which is explained below.The regenerative electronic load is used to compensate for the difference between the current and voltage values ​​at the connection terminal, which are set with the resistive load, and the current and voltage setpoints of the respective measuring point. The current and voltage setpoints of the measuring points are achieved by combining the resistive load with the regenerative electronic load. In addition, the regenerative electronic load makes it possible to generate a counter voltage and to absorb or release the power difference when the resistive load switches over. This ensures that the voltage is constant, so that the charging device does not interrupt the charging process during the test. The electronic load must be dimensioned so that the voltage range matches the charging device. The electronic load must be dimensioned so that the adjustable current range matches the energy storage unit.

[0021] The energy storage unit is designed to absorb power from or deliver power to the electronic load. For example, the energy storage unit can be a rechargeable battery or accumulator. The capacity of the energy storage unit must be high enough to provide a sufficiently high initial voltage and to compensate for the difference between the terminal current and the current setpoint. The capacity can be 30 kWh, for example, but other values ​​are possible.

[0022] All components of the device are dimensioned to withstand the current and voltage values ​​that occur during the charging process.

[0023] For example, the maximum voltage for testing the charging device is 800 V, 900 V, or 1000 V; other values ​​are possible. Typical charging device power ratings, depending on the type, are 22 kW, 50 kW, 100 kW, 150 kW, and / or 300 kW; other values ​​are possible.

[0024] For example, the measuring points of the charging device are at maximum voltage and minimum current, e.g. 1000 V and 1 A, at minimum voltage and maximum current, e.g. 150 V and 500 A, and at a measuring point in between, e.g. 400 V and 375 A; other values ​​are possible. It is possible for the voltage and / or current measuring unit to record individual measured values ​​for a large number of points in time. It is possible for an average, a variance, a maximum, a minimum, a median and / or other statistical values ​​to be calculated from the large number of measured values. It is possible for the voltage and / or current measuring unit to measure the frequency and the frequency components of the clamping voltage or the clamping current. It is possible for a processing unit to determine the current power and the amount of energy transferred over a period of time with the help of the current measuring unit and the voltage measuring unit.

[0025] Optionally, the measured values, a portion of the measured values, and / or values ​​calculated from them are stored on a memory module and / or transmitted to an external device, e.g., a computer and / or a display, using a communication module.

[0026] One embodiment provides that the device further comprises a first control module which, based on the measuring point, controls the contactor such that the resistive load has a total resistance such that the current target approximate value and the voltage target approximate value are set.

[0027] The first control module adjusts the resistance of the resistive load so that the clamping voltage and the clamping current are as close as possible to the approximate current and voltage setpoints of the measuring point. The first control module is connected to the resistive load for this purpose. Since the resistive load can only be adjusted in steps, depending on the approximate current and voltage setpoints, the current and voltage setpoints cannot always be achieved with the resistive load alone, but can only be approximated.

[0028] Accordingly, the power is calculated by multiplying the voltage value by the current value, both for the current value and for the setpoint value.

[0029] The advantage of this embodiment is that, depending on the respective measuring point, an approximation of the current and voltage target values ​​of the measuring point is already achieved. One embodiment provides that the device further comprises a second control module, which controls the regenerative electronic load based on the power difference.

[0030] The second control module adjusts the resistance of the regenerative electronic load so that the clamping voltage and the clamping current are as close as possible to the current setpoint and the voltage setpoint of the measuring point. The second control module is connected to the electronic load for this purpose. The regenerative electronic load thus compensates for the difference between the clamping voltage and the voltage setpoint of the measuring point, as well as between the clamping current and the current setpoint of the measuring point. Since the resistive load can only be adjusted in steps, depending on the approximate current setpoint and approximate voltage setpoint, the current setpoint and the voltage setpoint cannot always be achieved with the resistive load alone, but can only be approximated. The current setpoint and voltage setpoint are achieved by adjusting the regenerative electronic load accordingly.

[0031] One embodiment provides that the first control module adjusts the resistive load so that the power difference is at most 30 kW.

[0032] The resistive load has corresponding resistors so that by combining them, a total resistance of the resistive load can be set such that for all measuring points to be tested, a maximum deviation of the terminal voltage from the voltage setpoint and of the terminal current from the current setpoint is achieved, so that the power set thereby deviates from the power setpoint by a maximum of 30 kW.

[0033] The advantage is that the difference between the current power value and the target value is relatively small, and that this difference can then be compensated for by adjusting the electronic load accordingly. The resulting requirements for the electronic load can be met using commercially available components. One embodiment provides that the regenerative electronic load further comprises two inverters arranged between the rectifier and the energy storage unit and connected in series with the rectifier and the energy storage unit, such that the first of the two inverters converts a DC voltage from the energy storage unit into AC voltage, and the second inverter converts the AC voltage into a DC voltage.

[0034] The two inverters enable efficient and space-saving adjustment of the power dropped across the regenerative electronic load. This results in an efficient and space-saving adjustment of the clamping voltage and current, which correspond to the current setpoint and voltage setpoint of the respective measuring point. The use of two additional inverters enables cost-effective conversion of a DC voltage to an AC voltage and back to a DC voltage, which, for example, is different from the DC voltage from the energy storage unit.

[0035] One embodiment provides that the device is suitable for testing measuring points with a maximum power of at least 25 kW and a maximum voltage of at least 150 V.

[0036] All components and the connections between the components must be dimensioned and selected so that the device achieves a power of at least 25 kW and a voltage of at least 150 V.

[0037] This means that fast charging stations can also be tested with the device.

[0038] In particular, it is not possible to achieve such high power and voltage values ​​with a device without an electronic load, i.e., with only a resistive load. Especially at high power levels, a large portion of the power is absorbed by the resistive load. The large portion is preferably the power by which the power exceeds the 30 kW that the electronic load can absorb. One embodiment provides that the device is suitable for testing measuring points with a maximum power of 5000 kW and a maximum voltage of 1500 V.

[0039] The device is specifically designed for testing charging devices for electric vehicles such as electric cars, electric Sprinters, electric motorcycles, electric mopeds, electric scooters, and electric bicycles. Higher power or voltage requirements than are appropriate for this purpose would result in unnecessarily complex, expensive, inefficient, and / or space-consuming designs.

[0040] One embodiment provides that the resistors of the resistive load are designed and controllable in such a way that a current and voltage curve can be measured continuously by a combination of the resistive load and the regenerative electronic load.

[0041] This means that the regenerative electronic load and the resistive load are designed so that any clamping voltage and current between a predefined minimum and maximum can be achieved with the device. In particular, the regenerative electronic load can be designed to compensate for any differences between the step values ​​that can be set with the resistive load.

[0042] The advantage of this is that the complete charging process of a typical electric vehicle can be simulated.

[0043] Typically, a charging process begins with the pre-charge phase, where the battery is precharged to the battery voltage. Then, the system switches to the actual charging phase. During this switchover, a high current would flow very quickly in a testing device containing a resistive load but no electronic load or capacitor bank, but the voltage would drop sharply. This would cause the charging device to abort the charging process and thus the testing process, as this phenomenon, along with the dropping voltage, suggests that no battery or accumulator of an electric vehicle is connected. One embodiment provides for the first inverter and the second inverter to be bidirectional.

[0044] Bidirectional means that the inverters can input and output current. This has the advantage that the difference between the clamping current measured with the current measuring unit and the current setpoint of the respective measuring point can be compensated for both when the current clamping current is greater than the current setpoint and when the current clamping current is less than the current setpoint. This allows for a wider range of clamping current values. This enables a particularly efficient design of the device and the achievement of continuous current curves.

[0045] One embodiment provides that the second control unit of the regenerative electronic load controls the regenerative electronic load such that the device simulates the behavior of a battery of an electric vehicle.

[0046] This means that the device first increases the clamping voltage until a predefined clamping voltage corresponding to the countervoltage of an electric vehicle battery to be simulated is reached, then maintains this clamping voltage constant for a predefined period of time, and then reduces the clamping voltage. The clamping current is also modeled on the current curve that occurs when charging an electric vehicle battery.

[0047] The regenerative electronic load is controlled by the second control unit, accessing the currently measured clamping current at the current measuring unit and the currently measured clamping voltage at the voltage measuring unit. From these values, the second control unit calculates the difference to the respective current and voltage setpoints and adjusts the power drop across the regenerative electronic load accordingly, so that the clamping voltage and current correspond to the current and voltage setpoints.

[0048] In particular, the electronic load prevents a sudden voltage change from occurring when the resistors in the resistive load are switched. This offers the advantage of achieving a constant countervoltage, similar to that exhibited by an actual electric car battery connected to the charging device. If a sudden voltage change were to occur, the charging device would abort the charging process and thus also the test procedure.

[0049] One embodiment provides that the first control module or the second control module has a communication module for communicating with the charging device.

[0050] The communication module manages communication between the charging device and the device for testing the charging device. This communication corresponds to the communication between an electric vehicle and a charging device before and during the charging process of the electric vehicle's battery. For example, the device authenticates itself to the charging device, and conversely, the device receives information from the charging device about the charging device type and / or about maximum and minimum voltage, current, and / or power values. Furthermore, the communication module can inform the charging device about the device's voltage, since the charging device adjusts the voltage to the state of charge and thus to the battery voltage level during typical electric vehicle charging processes.

[0051] One embodiment provides that the device does not feed power back into a supply network.

[0052] This independence from the power grid is possible because the device has an energy storage unit and, with the combination of the resistive and electronic load, compensates for the differences between the clamping current and clamping voltage to the current and voltage target values. This offers the advantage that testing is also possible at locations where there is no access to the power grid. This allows testing to be carried out anywhere, e.g., in public spaces on streets or squares. The energy provided by the charging device and absorbed by the electronic load is fed back into the energy storage unit and not into the power grid. One embodiment provides for the energy storage unit to be an accumulator.

[0053] The accumulator has a capacity suitable for absorbing the power drawn by the electronic load during testing of a charging device. Advantageously, the capacity is sufficient to absorb the power of multiple test processes. Alternatively, any excess energy stored in the energy storage unit between different test processes can be transferred from the energy storage unit via the electronic load back to the resistive load, thereby converting it into heat, or, in the case of a bidirectional charging device, fed into the grid via the charging device.

[0054] One embodiment provides that the processing unit uses the voltage measuring unit and the current measuring unit to determine the power and the amount of energy transmitted over a predetermined period of time.

[0055] This means that the terminal voltage and current transmitted by the charging device to the terminals are determined at the respective measuring point by the current measuring unit and the voltage measuring unit. The processing unit uses the measured terminal voltages and currents to determine the amount of energy transmitted, which can be compared with the amount of energy billed by the charging device.

[0056] With a maximum power to be tested of 22 kW, it is also possible to use no resistive load, but only the regenerative electronic load. The maximum achievable power is then determined by the maximum that the inverters can achieve, which, according to the current state of the art for inverters, is approximately 22 kW.

[0057] One embodiment provides that the energy storage unit is the supply network.

[0058] The power difference can also be provided or absorbed by the supply grid in addition to or as an alternative to the energy storage unit. In other words, the device can be coupled to the supply grid.

[0059] In particular, it can be provided that the power difference is provided or absorbed by an AC supply network. For example, the device can be connected to the supply network by means of an electrical connection. It is also conceivable for the device to be connected to an AG charging device that is different from the charging device to be tested. In this embodiment, it can be provided that the device, in addition to the rectifier, has at least one inverter or precisely one inverter that converts the DC voltage provided by the rectifier into an AC voltage.

[0060] This has the advantage that larger amounts of energy can be fed into or taken from the supply grid.

[0061] A further aspect of the invention relates to a vehicle with a device for testing a charging device according to the above explanations. The vehicle can be a motor vehicle, e.g. a passenger car, or a trailer that can be attached to a motor vehicle or another vehicle. In particular, the vehicle can be a trailer for a passenger car. This enables flexible mobile testing of charging devices in public spaces, as even narrow streets can be reached. This offers particular advantages over previous alternatives using capacitor banks that are so large and heavy that a truck or truck trailer is required, making narrower streets and squares inaccessible.

[0062] Fig. 1 shows a device for testing a charging device for electric vehicles. Fig. 2 shows a vehicle with a device for testing a charging device for electric vehicles.

[0063] Fig. 3 shows a vehicle with a device for testing a charging device for electric vehicles, the device comprising two control units.

[0064] Fig. 4 shows a vehicle with a device connected to a charging device.

[0065] The exemplary embodiment explained below is a preferred embodiment of the invention. In the exemplary embodiment, the described components of the embodiment each represent individual, independently considered features of the invention, which also further develop the invention independently of one another and are thus also to be considered as components of the invention, either individually or in a combination other than that shown. Furthermore, the described embodiment can also be supplemented by further features of the invention already described.

[0066] Fig. 1 shows a device 1 for testing a charging device 2 (not shown here) for electric vehicles. The electric vehicles can be, for example, electric cars, hybrid cars, electric sprinters, electric motorcycles, electric mopeds, electric mopeds, electric bicycles, or electric scooters, although this list is not exhaustive. The device 1 comprises a connection terminal 10. The connection terminal 10 serves for the electrical connection to the charging device 2. The connection terminal 10 can be a power cable with a power plug, the dimensioning of which is sufficient for the corresponding voltage and current ranges. Furthermore, the device 1 comprises a resistive load 20. The resistive load 20 is adjustable in steps and connected in parallel to the connection terminal. For this purpose, the resistive load 20 comprises a plurality of resistors that can be combined in various ways, so that a multitude of different total resistance values ​​of the resistive load 20 can be set.The resistive load 20 serves to achieve a current value and a voltage value at the connection terminal 10 that is as close as possible to the current setpoint and the voltage setpoint.

[0067] Furthermore, the device 1 comprises a regenerative electronic load 30. The regenerative electronic load 30 comprises at least one rectifier 32 and is connected in series with the connection terminal 10. The regenerative electronic load 30 serves to compensate for the difference between the terminal current, i.e., the current at the connection terminal 10, and the current setpoint, as well as between the terminal voltage, i.e., the voltage at the connection terminal 10, and the voltage setpoint.

[0068] The device 1 further comprises an energy storage unit 40. The energy storage unit 40 can be a rechargeable battery or accumulator. The device 1 further comprises a voltage measuring unit 50 and a current measuring unit 60. The voltage measuring unit 50 measures the voltage at the connection terminal 10. The current measuring unit 60 measures the current at the connection terminal 10.

[0069] Fig. 2 shows a vehicle 3 with a device 1 for testing a charging device 2 for electric vehicles. The vehicle 3 can be, for example, a car or a trailer for attaching to a car, a motorcycle, or the like, although this list is not exhaustive. The device 1 can be designed as described for Fig. 1. Alternatively, it is possible for the electronic load 30 to have, in addition to the rectifier 32, two inverters 34, 35 connected in series with the rectifier 32. This offers the advantage that inverters are already commercially available in highly optimized sizes and dimensions, so that the weight and dimensions can be kept low.

[0070] Fig. 3 shows a vehicle 3 with a device 1 for testing a charging device 2 for electric vehicles, wherein the device 1 comprises, in addition to the example from Fig. 2, two control modules 70, 80. The first control module 70 controls the resistive load 20 so that it sets a total resistance such that the difference between the clamping voltage and the voltage setpoint and between the clamping current and the current setpoint is as small as possible, advantageously such that the deviation from the power setpoint is less than 20%. The first control module 70 is connected to the resistive load 20 for this purpose. The second control module 80 controls the electronic load 30 so that a power drop occurs across it so that the difference between the clamping voltage and the voltage setpoint and between the clamping current and the current setpoint is within a given tolerance. The tolerance can be, for example, 2% or 5% or, for example,10% for low power ranges, e.g., for power outputs < 22 kW. For this purpose, the first control module 80 is connected to the electronic load 30. The voltage measuring unit 50 and / or the current measuring unit 60 can be connected to a processing unit 90. The processing unit 90 is designed to evaluate and process the measured values ​​provided by the voltage measuring unit 50 and the current measuring unit 60. In particular, it can be provided that the processing unit determines an energy quantity based on the measured values ​​provided by the voltage measuring unit 50 and the current measuring unit 60. The determination can be based on the power as a function of time.

[0071] Fig. 4 shows a vehicle 3 with a device 1 connected to a charging device 2. The charging device 2 is connected to the device 1 via the connection terminal 10. The device can be designed as in the previous figures.

[0072] In detail, a step-adjustable resistive load 20 is used, which uses contactors to switch various resistors on or off. However, a resistive load 20 cannot be used alone for testing charging devices 2. Charging device 2 expects the behavior of a vehicle battery, which permanently generates a nearly constant countervoltage. This also occurs when charging device 2 is not yet supplying a charging voltage or when the current changes. A resistive load 20 cannot generate this countervoltage. To make matters worse, the resistors in resistive load 20 are switched using contactors when the current changes. Since charging device 2 has a briefly sluggish behavior and thus does not supply the new current target value immediately, the voltage at resistive load 20 would drop or increase during this short period of time.However, these larger voltage changes lead to an interruption of the charging process by charging device 2. Therefore, not only must the countervoltage be generated, but the power difference at the switching moments must also be compensated. For this purpose, a regenerative electronic load 30 is connected in parallel with the resistive load 20. This can generate the countervoltage and absorb or release the power difference at the switching moments of the resistive load 20.

[0073] In detail, a 230 / 400 V three-phase network with bidirectional 32 A inverters and an energy storage unit 40 in a vehicle 3, e.g., in a motor vehicle or in a trailer, can be used for this power supply and consumption. The three-phase network enables the power consumption. The regenerative electronic load 30 connected to the bidirectional inverters 34, 35 can store the required power in the energy storage unit 40 via the inverters 34, 35 or make it available from the energy storage unit 40. The electronic load 30 uses this power to compensate for the power difference in the switching moments of the resistive load 20 and serves to provide the necessary counter voltage.The innovation lies in the combination of the regenerative electronic load 30, which has so far only been used in the laboratory, with a resistive load 20 in order to be able to test higher power ranges on charging devices 2 on the move.

[0074] One advantage of the invention is that high charging powers of, for example, up to 300 kW can be taken from charging devices 2 and tested on a mobile basis. This would only be possible with up to 22 kW if an energy storage unit 40, an inverter 34 and a regenerative electronic load 30 were used exclusively. In addition, without the inventive parallel connection with the electronic load 30, the resistive load 20 can only set individual fixed stages, which result from the interconnection of the individual resistors in the resistive load 20. With the inventive parallel connection of the resistive load 20 and the electronic load 30, not only these fixed stages can be set dynamically, but also continuous test points between the individual stages. This is important because the necessary voltage and current setpoints of the test points differ for the individual charging device types depending on the capabilities of the charging device 2.Furthermore, the combination of resistive load 20, electronic load 30, and energy storage unit 40 is comparatively light at approximately 500 kg and, at approximately €110,000, relatively inexpensive for its high power consumption. The invention can be transported on a car trailer and, for mobile applications, for example, in inner cities, offers a significant mobility advantage over the heavier solution using capacitor banks, which requires a truck. Capacitor banks prevent a drop in power when starting the charging or testing process, preventing the charging device from aborting the charging process, as would be the case when using a purely resistive load. However, capacitor banks cannot ensure that current and voltage values ​​can be flexibly adjusted.Therefore, a different resistive load-capacitor bank combination is required depending on the charging device type, as different current and voltage setpoints must be achieved. Furthermore, the capacitor banks must be precharged, e.g., with a battery. Another alternative option is the sole use of a resistive load 20, which, however, can only be used with charging devices 2 that do not perform the standardized voltage tolerance test. Furthermore, only fixed voltage and current setpoints can be set for the test points, so this is only sufficient for testing individual charging device types.

[0075] The invention can be used, on the one hand, for the conformity assessment according to Modules B, D, and F when testing charging devices 2 directly at the installation site. Furthermore, charging devices 2 can also be metrologically tested and thus calibrated using the invention.

[0076] List of reference symbols

[0077] 1 device for testing a charging device

[0078] 2 Charging device 3 Vehicle

[0079] 10 connection terminal

[0080] 20 resistive load

[0081] 30 regenerative electronic loads

[0082] 32 Rectifier 34 First inverter

[0083] 35 second inverter

[0084] 40 energy storage units

[0085] 50 voltage measuring unit

[0086] 60 Current measuring unit 70 Resistive load control unit

[0087] 80 Control unit of the regenerative electronic load

[0088] 90 Processing unit of the current and voltage measuring unit

Claims

Patent claims 1. Device (1) for testing a charging device (2) for electric vehicles by measuring from a predefined electrical measuring point, each measuring point having a current setpoint and a voltage setpoint, comprising - a connection terminal (10) for electrical connection to the charging device (2); - a stepwise adjustable resistive load (20), wherein the stepwise adjustable resistive load (20) has a plurality of predefined resistors, each of which can be switched on by means of a contactor, so that the stepwise adjustable resistive load (20) has a total resistance based on the switched-on resistors, so that an approximate current target value and an approximate voltage target value are set at the connection terminal (10), wherein the stepwise adjustable resistive load (20) is connected in parallel to the connection terminal (10); - a regenerative electronic load (30) connected in parallel to the connection terminal (10) and to the adjustable resistive load (20), wherein the regenerative electronic load (30) comprises at least one rectifier (32), so that the regenerative electronic load (20) provides a terminal voltage dropped across the connection terminal (10) and / or absorbs or emits a power difference resulting from the product of a current difference between the current setpoint value and the current setpoint approximate value with the voltage setpoint approximate value and / or from the product of a voltage difference between the voltage setpoint value and the voltage setpoint approximate value with the current setpoint approximate value, wherein the absorbed power difference is fed into an energy storage unit (40) or the emitted power difference is fed from the energy storage unit (40): - a voltage measuring unit (50) for measuring the terminal voltage; and - a current measuring unit (60) for measuring a terminal current.

2. Device (1) according to claim 1, further comprising a first control module (70) which, based on the measuring point, controls the contactor such that the resistive load (20) has a total resistance such that the current target approximate value and the voltage target approximate value are set.

3. Device (1) according to one of the preceding claims, further comprising a second control module (80) which controls the regenerative electronic load (30) based on the power difference.

4. Device (1) according to claim 2, wherein the first control module (70) adjusts the resistive load (20) such that the power difference is at most 30 kW.

5. Device (1) according to one of the preceding claims, wherein the regenerative electronic load (30) further comprises two inverters (34, 35) arranged between the rectifier (32) and the energy storage unit (40) and connected in series with the rectifier (32) and the energy storage unit (40), such that the first of the two inverters (34) converts a DC voltage of the energy storage unit (40) into AC voltage and the second inverter (35) converts the AC voltage into a DC voltage.

6. Device (1) according to one of the preceding claims, wherein the device is suitable for testing measuring points with a maximum power of at least 25 kW and a maximum voltage of at least 150 V.

7. Device (1) according to one of the preceding claims, wherein the device is suitable for testing measuring points with a power of at most 5000 kW and a voltage of at most 1500 V.

8. Device (1) according to one of the preceding claims, wherein the resistors of the resistive load (20) are designed and controllable in such a way that by a Combination of the resistive load (20) and the regenerative electronic load (30) allows a current and voltage curve to be measured continuously.

9. Device (1) according to one of claims 5 to 8, wherein the first inverter (34) and the second inverter (35) are bidirectional.

10. Device (1) according to one of claims 3 to 9, wherein the second control unit (80) controls the regenerative electronic load (30) such that the device (1) simulates the behavior of a battery of an electric vehicle.

11. Device (1) according to one of claims 3 to 10, wherein the first control module (70) or the second control module (80) has a communication module for communicating with the charging device (2).

12. Device (1) according to one of the preceding claims, wherein the device (1) does not feed any current back into a supply network.

13. Device (1) according to one of the preceding claims, wherein the energy storage unit (40) is an accumulator.

14. Device (1) according to one of claims 1 to 11, wherein the energy storage unit (40) is the supply network.

15. Device (1) according to one of the preceding claims, wherein a processing unit (90) determines the power and an amount of energy transmitted over a predetermined period of time using the voltage measuring unit (50) and the current measuring unit (60).

16. Vehicle (3) with a device (1) according to one of the preceding claims.

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