Monitoring device for a charging device, charging device, and method for monitoring a charging device

Abstract

Monitoring a charging device for an electric vehicle. An efficiency of the charging device is calculated from a power flow into the charging device and a power flow out of the charging device. This efficiency can be compared with a previously determined nominal efficiency of the charging device for the respective working point of the charging device. In the event of a deviation, a malfunction can be detected.

Description

[0001] Description

[0002] title

[0003] Monitoring device for a charging device., Charging device, and method for monitoring a charging device

[0004] Technical area

[0005] The present invention relates to a monitoring device for a charging device, in particular a charging device for an electric vehicle. The present invention further relates to a charging device for an electric vehicle having such a monitoring device and a method for monitoring a charging device for an electric vehicle.

[0006] background

[0007] Vehicles that are fully or at least partially electrically powered have an electrical energy storage device that can provide energy for the vehicle's electric drive system. To charge this electrical energy storage device, the vehicle can be coupled to an external energy source so that the electrical energy storage device can be charged using energy from this external energy source. For this purpose, a charging device can be provided in the vehicle, for example. Using such a charging device, the electrical voltage provided by the external energy source can be converted into a voltage suitable for charging the vehicle's energy storage device. In addition, the charging device can also regulate parameters such as voltage, current, charging power, or the like during the charging process.

[0008] The document DE 10 2019 215 645 A1, for example, describes a charger for charging a traction battery in an electric vehicle using energy from an electrical AC voltage source.

[0009] Disclosure of the Invention The present invention provides a device for monitoring a charging device, in particular a charging device for an electric vehicle, a charging device for an electric vehicle, and a method for monitoring a charging device for an electric vehicle with the features of the independent patent claims. Further advantageous embodiments are the subject of the dependent patent claims.

[0010] Accordingly, it is provided:

[0011] A monitoring device for monitoring a charging device, in particular a charging device for an electric vehicle. The monitoring device is designed to determine a first power flow at an AC interface of the charging device. The monitoring device is further designed to determine a second power flow at a battery interface of the charging device. Furthermore, the monitoring device is designed to calculate an efficiency of the charging device. The efficiency can be calculated, in particular, by comparing the first power flow at the AC interface and the second power flow at the battery interface. Finally, the monitoring device is designed to detect a malfunction of the charging device.The monitoring device can detect a malfunction of the charging device, in particular, if the calculated efficiency of the charging device deviates from a current nominal efficiency of the charging device. In particular, a malfunction can be detected if the calculated efficiency deviates from the current nominal efficiency by more than a predetermined threshold.

[0012] Furthermore, it is planned:

[0013] A charging device for an electric vehicle with an AC interface, a battery interface, a charging circuit, and a monitoring device according to the invention. The AC interface is designed to be coupled to a power grid. The battery interface is designed to be coupled to a traction battery of an electric vehicle. The charging circuit is designed to convert an electrical voltage provided at the AC charging circuit into a further voltage. This further voltage can be suitable for charging the traction battery. Finally, the following is provided:

[0014] A method for monitoring a charging device for an electric vehicle. The method comprises a step for determining a first power flow at an AC interface of the charging device. Furthermore, the method comprises a step for determining a second power flow at a battery interface of the charging device. According to Berner, the method comprises a step for calculating an efficiency of the charging device. The efficiency of the charging device is calculated in particular using a comparison of the first power flow with the second power flow. Finally, the method comprises a step for detecting a malfunction of the charging device. A malfunction of the charging device can be detected in particular if the calculated efficiency of the charging device deviates from a current nominal efficiency of the charging device by more than a predetermined threshold value.

[0015] The present invention is based on the finding that the detection and monitoring of the currents and voltages occurring is particularly important for controlling a charging device for an electric vehicle. Therefore, it is desirable to monitor the corresponding sensor values ​​for these currents and voltages. This can prevent, for example, malfunctions or damage to components if the control is based on incorrect sensor values. However, a redundant design of the sensors for plausibility checks requires significant hardware and costs.

[0016] Therefore, one idea of ​​the present invention is to verify the plausibility of the sensor values ​​of currents and voltages on the input and output sides of such a charging device by comparing the power flow and taking into account an operating point-dependent efficiency. If the efficiency of the charging device deviates from an expected nominal efficiency at the respective operating point based on the sensor values, this can be interpreted as an indication of a possible fault in the charging device or at least one sensor.

[0017] The AC interface of the charging device can, for example, be an interface at which the charging device can be coupled to an external AC voltage source. Both a single-phase and a multi-phase AC voltage source are possible, and these can be coupled to the charging device at the AC interface. The battery interface of the charging device is designed to be coupled to an electrical energy storage device, such as the traction battery of an electric vehicle. In this way, for example, an AC voltage provided by an external AC voltage source at the AC interface can be converted by the charging device into a DC voltage suitable for charging an electrical energy storage device connected to the battery interface.The first power flow corresponds to the electrical energy flowing from the external energy source into the charging device. The second power flow refers to the power delivered by the charging circuit at the battery interface to the energy storage device. The difference between the first power flow and the second power flow thus describes the losses within the charging circuit, which can be characterized by a corresponding efficiency of the charging circuit. If the charging device is operated inversely, i.e. if electrical energy is transferred from the traction battery to the AC interface, then in this case too the electrical power flowing in at the battery interface can be compared with the power delivered at the AC interface.

[0018] In this context, the nominal efficiency describes the expected efficiency of the charging circuit. This nominal efficiency can be determined, for example, through previous measurements or simulations.

[0019] If a significant difference occurs between the actual current efficiency and the expected nominal efficiency, this can be interpreted as an indication of a possible fault in the charging circuit. The sensor variables such as currents and voltages used to determine the power flows can also be used for other purposes, in particular, for example, to control the charging device. Therefore, it is crucial to monitor and verify the plausibility of these sensor variables during operation of the charging device. The inventive concept for monitoring the charging device based on monitoring the power flows enables such monitoring and plausibility checks of the sensor variables without the need for additional hardware components, such as redundant sensors or the like.According to one embodiment, the monitoring device is designed to determine the first power flow using sensor values ​​for current and voltage at the AC voltage interface. Additionally or alternatively, the monitoring device can be designed to determine the second power flow using sensor values ​​for current and voltage at the battery voltage interface. Instead of the sensor values ​​for current and voltage at the battery interface, setpoint values ​​for current or voltage at the battery interface can alternatively be used to determine the second power flow. In principle, a combination of requested setpoints and sensor values ​​is also conceivable. The electrical power can be calculated in the known manner by the integral of the product of current and voltage.In the case of alternating voltages and currents, for a reliable calculation of the power flow on the AC side, the power flow should preferably be considered over an integer multiple of the period of the alternating voltage. This is particularly crucial when considering the power flow over relatively short periods.

[0020] With

[0021] P: power flow x: integer multiple of the period

[0022] T: period u: electrical voltage i: electrical current

[0023] According to one embodiment, the monitoring device is designed to determine the current nominal efficiency of the charging device using the determined first power flow and / or the determined second power flow. For this purpose, for example, a characteristic curve of the efficiency of the charging device as a function of the power flow can be determined in advance. The determination of the characteristic curve for the nominal efficiency can be based on measurements and / or simulations. According to one embodiment, the monitoring device is designed to further determine the current nominal efficiency using at least one further operating parameter. In one embodiment, the at least one further operating parameter can include, for example, a measured or calculated or estimated temperature of the charging device.The temperature can be estimated, for example, based on a predefined mathematical model. To determine the temperature, one or more temperature sensors can be installed in the charging device, which provide sensor values ​​for the temperature of the charging device. In this way, a temperature-dependent variation in the nominal efficiency can also be taken into account. Furthermore, any other parameters that influence the efficiency of the charging device can, of course, also be considered.

[0024] According to one embodiment, the monitoring device comprises a storage device. The storage device is designed to provide data for a relationship between nominal efficiency and operating parameters of the charging device. In particular, the data can specify a relationship between nominal efficiency and the power flow at the AC interface and / or at the battery interface. Furthermore, the data can also specify the dependence of the nominal efficiency on further operating parameters, such as the temperature in the charging device. The data can be provided, for example, as a log or simulation model. Alternatively, the data can also be provided, for example, in the form of a table, for example a look-up table.The monitoring device can be designed to determine the current nominal efficiency using the data provided by the storage device.

[0025] According to one embodiment, the monitoring device is designed to temporally filter the determined first power flow and / or the determined second power flow. For example, the filtering can comprise averaging over a predetermined period of time. Furthermore, any other methods for filtering or smoothing the determined power flow are of course also possible. In this way, short-term fluctuations, jumps, and the like can be compensated. The monitoring device can then calculate the efficiency of the charging device using the filtered values. By temporally filtering or smoothing the values, a response of the error detection in the case of short-term power jumps, fluctuations, or the like can be avoided.

[0026] According to one embodiment, the monitoring device is designed to deactivate the charging device upon detection of an error in the charging device. This can prevent further damage to components in the charging device or components connected to the charging device. Additionally or alternatively, an error message can also be output as an electronic, visual, and / or acoustic signal.

[0027] According to one embodiment, the charging device is designed to convert an electrical direct voltage provided at the battery interface into a single- or multi-phase alternating voltage and to provide this alternating voltage at the AC voltage connection. In this way, an inverse energy transfer is also possible from an electrical energy storage device connected to the battery interface to the AC voltage interface and further to a consumer connected to the AC voltage interface or a connected power grid. In this case, too, potential fault detection can be carried out by evaluating the power flows at the battery interface and the AC voltage interface and comparing the resulting efficiency with a corresponding nominal efficiency.

[0028] The above embodiments and further developments can be combined with one another 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 respect 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.

[0029] Short description of the drawings

[0030] Further features and advantages of the invention are explained below with reference to the figures. Figure 1 shows a schematic block diagram of a charging device with a monitoring device according to one embodiment;

[0031] Fig. 2: a schematic representation of a block diagram of a charging device with a monitoring device according to a further embodiment; and

[0032] Fig. 3: a flowchart underlying a method for monitoring a charging device according to an embodiment.

[0033] Description of embodiments

[0034] Figure 1 shows a schematic representation of a block diagram of a charging device 1 according to one embodiment. The charging device 1 can be used, for example, to charge an electrical energy storage device 3, such as the traction battery of an electric vehicle, using electrical energy from an external energy source 2. The external energy source 2 can be, for example, a single-phase or multi-phase connection to an AC voltage network. The electrical energy storage device 3 can be a traction battery, such as those used, for example, in fully or at least partially electrically powered vehicles.

[0035] The charging device 1 comprises an AC voltage interface 11. At this AC voltage interface 11, the charging device 1 can be coupled to the external energy source 2. Furthermore, the charging device 1 comprises a battery interface 12. The energy storage device 3 can be electrically coupled to this battery interface 12. Furthermore, the charging device 1 comprises a charging circuit 13. This charging circuit 13 can be coupled, on the one hand, to the AC voltage interface 11 and, on the other hand, to the battery interface 12. In particular, the charging circuit 13 can convert an AC voltage provided by the external energy source 2 at the AC voltage interface 11 into a DC voltage and provide it to the battery interface 12.

[0036] The charging device 1 can, for example, comprise current sensors 11a and voltage sensors 11b, which detect the currents and voltages on the AC voltage side of the charging device 1 and provide sensor variables corresponding to the currents and voltages. These current and voltage sensors 11a, 11b can, for example, be provided in the AC voltage interface 11. Likewise, a current sensor 12a and a voltage sensor 12b can be provided, which detect the current and voltage for the electrical energy storage device 3 on the DC voltage side and output corresponding sensor signals. These current and voltage sensors 12a, 12b can, for example, be provided in the battery interface 12.

[0037] The charging circuit 13 can receive the sensor variables from the current sensors 11a, 12a and the voltage sensors 11b, 12b and then regulate the operation within the charging circuit 13 accordingly. Accordingly, an error in the sensor signal of one of the sensors 11a, 11b, 12a, 12b will affect the control of the charging circuit 13. Therefore, a monitoring device 10 is provided to monitor the operation of the charging device 1. This monitoring device 10 can, for example, be provided within the charging device 1. Alternatively, however, it is also possible to provide the monitoring device 10 outside the charging device 1, for example, in an external control unit or a separate control unit.

[0038] The monitoring device 10 can receive the current signals from the current sensors 11a and the voltage sensors 11b on the AC side, as well as the signals from the current sensor 12a and the voltage sensor 12b on the DC side of the charging device 1. Based on the received sensor signals, the monitoring device 10 can determine a power flow on the AC side, in particular at the AC interface 11. The electrical power can be calculated in a known manner by the integral of the product of current and voltage. In the case of AC voltages and currents, for a reliable calculation of the power flow on the AC side, the power flow should preferably be considered over an integer multiple of the period of the AC voltage. This is particularly crucial when considering the power flow for relatively short periods.

[0039] Similarly, a power flow can also be calculated on the DC side using the sensor signals from the current sensor 12a and the voltage sensor 12b. This can be the power flow through the battery interface 12. Due to the losses within the charging device 1, more energy will flow into the charging device 1 at the AC interface 11 during charging operation than will flow out of the charging device 1 at the battery interface 12. Accordingly, the efficiency of the charging device 1 can be calculated in a conventional manner from the ratio of the energy flow at the AC interface 11 and the energy flow at the battery interface 12.

[0040] Furthermore, the monitoring device 10 can compare the efficiency of the charging device 1 calculated in this way with a corresponding nominal efficiency. This nominal efficiency can represent an efficiency that has previously been determined for the charging device 1 by measurement or simulation. When determining the nominal efficiency, current operating conditions, such as the current operating point of the charging circuit 13 and the like, can also be taken into account. Thus, the nominal efficiency of the charging device 1 can be specified, for example, as a one- or multi-dimensional characteristic field depending on the respective operating parameters of the charging device 1. The operating parameters can be, for example, the power flow at the AC interface 11, the power flow at the battery interface 12 and / or other operating parameters such asa temperature in the charging device 1. In this case, the monitoring device 10 can determine the applicable nominal efficiency of the charging device 1 for the current operating conditions and compare this with the calculated actual efficiency according to the current and voltage measurements.

[0041] If the calculated actual efficiency of the charging device 1 deviates from the nominal efficiency for the prevailing operating conditions, this can indicate a fault within the charging device 1. For example, a fault in the charging device 1 can be detected if an absolute or relative deviation of more than a predetermined threshold is detected between the calculated efficiency of the charging device 1 and the nominal efficiency for the current operating conditions. Upon detection of such a fault, the monitoring device 10 can, for example, initiate a shutdown or deactivation of the charging device 1.

[0042] For example, a malfunction in one of the sensors 11a, 11b, 12a, 12b can result in the sensor value of a current or voltage sensor not corresponding to the actual current or voltage. Accordingly, the calculation of the respective power flow would result in a value that is too large or too small for the power flow. This subsequently leads to a deviation in the calculated efficiency, in particular to an efficiency that deviates from the nominal efficiency for the respective operating conditions. Thus, sensor errors can be easily detected using the procedure described.

[0043] Berner also considers the possibility that a hardware defect within charging device 1 could result in more energy being converted than would be the case during fault-free operation. This increased energy conversion, which leads to greater power loss, also affects the actual efficiency of charging device 1 and can thus be detected by comparing it with the nominal efficiency.

[0044] Figure 2 shows a schematic representation of a block diagram for a charging device 1 according to another embodiment. All statements made previously in connection with Figure 1 also apply to this embodiment. The following statements can also be applied, where applicable, to the embodiment previously described in connection with Figure 1.

[0045] As can be seen in Figure 2, a storage device 10a can be provided, for example, in the monitoring device 10. This storage device 10a can store and provide data for the nominal efficiency as a function of the operating parameters of the charging device 1. Thus, using this data provided by the storage device 10a, the monitoring device 10 can easily compare the calculated efficiency with the nominal efficiency provided by the storage device 10a in order to check the data from the sensors 11a, 11b, 12a, 12b. The data for the nominal efficiency can be provided in any suitable manner. For example, a formula or algorithm that describes the nominal efficiency as a function of the operating parameters can be stored in the storage device 10a.Alternatively, data can also be calculated and saved in advance, for example in the form of a look-up table or similar. Furthermore, any other options for storing and providing the data for the nominal efficiency of the charging device 1 are possible. In addition to the already described dependence of the nominal efficiency on the currently converted power, in particular the power flow at the AC interface 11 and / or the power flow at the battery interface 12, other operating parameters can also influence the current nominal efficiency. For example, an operating temperature of the charging device 1 can also be detected by means of a temperature sensor 18. In this case, the nominal efficiency can also be determined as a function of the operating temperature.Alternatively, an operating temperature within the charging device 1 can be calculated or determined in another way, for example based on other operating parameters such as current and / or voltage within the charging device 1. However, it is understood that a dependence of the nominal efficiency on other operating parameters can also be taken into account.

[0046] The charging device 1, in particular the charging circuit 13, can comprise an AC / DC converter 14, as shown, for example, in Figure 2. This AC / DC converter 14 can, for example, first convert an AC voltage provided at the AC voltage connection 11 into a DC voltage and then provide the DC voltage to an intermediate circuit 16. Furthermore, the charging circuit 13 can, for example, comprise a DC-DC converter 15, which converts the DC voltage of the intermediate circuit 16 into a further DC voltage for charging the electrical energy storage device 3. In this way, the voltage level for charging the energy storage device 3 can be easily adjusted. This can also be used, for example, to regulate the charging power.

[0047] If, for example, an additional voltage sensor 17 is available in the intermediate circuit 16, the electrical voltage determined by this voltage sensor 17 can be used to verify the plausibility of the voltage values ​​from the voltage sensor 11b at the AC voltage interface 11 or the voltage sensor 12b at the battery interface 12. In this way, the fault location can be narrowed down if a fault is detected. In particular, it can be determined, for example, whether the fault involves a faulty current or voltage sensor 11a, 11b on the AC voltage side or a faulty sensor 12a, 12b on the DC voltage side. In the approaches described above, the sensor values ​​of the current sensor 12a and the voltage sensor 12b were used to calculate the power flow at the battery interface 12.Alternatively, it is also fundamentally possible to calculate the power flow at the battery interface 12, for example, based on setpoint specifications for the corresponding current and voltage values. In this way, the sensor-detected values ​​of the current and voltage sensors 12a, 12b do not have to be used directly. However, since these sensor values ​​of the current and voltage sensors 12a, 12b are used to control the charging circuit 13, a discrepancy in the power flows would result from the faulty sensor values ​​in the event of a fault, whereby the calculated efficiency based on the power flow based on the sensor values ​​at the AC interface would also deviate from the nominal efficiency for this operating point. Thus, a possible sensor error can also be detected with this approach.

[0048] To avoid erroneous error detection in the case of short-term power surges or fluctuations, the sensor values ​​or the resulting power flows can be filtered or averaged over a specified time interval, for example, in the range of one second. However, depending on the application, other time intervals are also possible, for example, 0.1 second, 0.5 seconds, 2 seconds, 5 seconds, or more. This can prevent erroneous error detection in the case of power surges or short-term fluctuations.

[0049] In addition to the previously described power flow from the AC voltage source 2 into the charging device 1 and on to the electrical energy storage device 3, it is also possible to operate the charging device 1 in the opposite direction, if necessary. This makes it possible, for example, to operate an electrical load at the AC voltage connection 11 of the charging device 1 using electrical energy from the energy storage device 3. Alternatively, an AC voltage provided at the AC voltage interface 11 can also be fed into a power grid. Even with such an energy flow, it is possible to calculate an efficiency for the charging device 1 by comparing the power flow at the battery interface 12 with the power flow at the AC voltage interface 11 and to compare this efficiency with a nominal efficiency corresponding to the respective operating or working point.Accordingly, possible errors can also be detected when the energy flow is in the inverse direction.

[0050] Finally, Figure 3 shows a flowchart underlying a method for monitoring a charging device 1 for an electric vehicle according to one embodiment. The method can, in principle, comprise any steps as previously described in connection with the monitoring device 10 or the charging device 1. Analogously, these previously described elements, such as the charging device 1 or the monitoring device 10, can also comprise any components suitable for implementing the method described below.

[0051] In step S1, a first power flow is determined. This first power flow can be the power flow at the AC interface 11 of the charging device 1. Furthermore, in step S2, a second power flow is determined. This second power flow can be the power flow at the battery interface 12 of the charging device 1. In step S3, an efficiency of the charging device 1 is then calculated. The efficiency is calculated using a comparison of the first power flow and the second power flow. Subsequently, in step S4, a malfunction of the charging device 1 can be detected if the calculated efficiency of the charging device 1 deviates from a current nominal efficiency of the charging device 1.In particular, a malfunction can be detected if the current efficiency deviates from the nominal efficiency by more than a specified threshold.

[0052] A suitable reaction can then be triggered, for example issuing an error message or switching off the charging device 1.

[0053] The current nominal efficiency can, in particular, be an efficiency that corresponds to an efficiency previously determined by measurement and / or simulation for the respective current operating point or the current operating parameters. The operating point of the charging device 1 can depend, for example, on the current charging power, for example, the first power flow and / or the second power flow. Furthermore, other operating parameters such as the operating temperature of the charging device 1 or the like can also be considered for determining the current nominal efficiency.

[0054] In summary, the present invention relates to a monitoring system for a charging device for an electric vehicle. From a power flow into the

[0055] The charging device's efficiency can be calculated based on the power flow into and out of the charging device. This efficiency can be compared with a previously determined nominal efficiency of the charging device for the current operating point. If there is a deviation, an error function can be detected.

Claims

Claims 1. Monitoring device (10) for monitoring a charging device (1) for an electric vehicle, wherein the monitoring device (10) is designed to determine a first power flow at an AC interface (11) of the charging device (1), to determine a second power flow at a battery interface (12) of the charging device (1), to calculate an efficiency of the charging device (1) using a comparison of the first power flow and the second power flow, and to detect an error function of the charging device (1) if the calculated efficiency of the charging device (1) deviates from a current nominal efficiency of the charging device (1) by more than a predetermined threshold value.

2. Monitoring device (10) according to claim 1, wherein the monitoring device (10) is designed to determine the first power flow using sensor values ​​for current and voltage at the AC voltage interface (11), and / or wherein the monitoring device (10) is designed to determine the second power flow using sensor values ​​and / or setpoint values ​​for current and voltage at the battery voltage interface (12).

3. Monitoring device (10) according to claim 1 or 2, wherein the monitoring device (10) is designed to determine the current nominal efficiency using the first power flow and / or the second power flow.

4. Monitoring device (10) according to claim 3, wherein the monitoring device (10) is designed to determine the current nominal efficiency further using at least one further operating parameter of the charging device (1).

5. Monitoring device (10) according to claim 4, wherein the at least one further operating parameter comprises a measured or estimated temperature of the charging device (1).

6. Monitoring device (10) according to one of claims 1 to 5, comprising a storage device (10a) which is designed to provide data for a relationship between nominal efficiency and operating parameters of the charging device (10), and wherein the monitoring device (10) is designed to determine the current nominal efficiency using the data provided by the storage device (10a).

7. Monitoring device (10) according to one of claims 1 to 6, wherein the monitoring device (10) is designed to filter the determined first power flow and / or the determined second power flow over time and to calculate the efficiency of the charging device (1) using the filtered values.

8. A charging device (1) for an electric vehicle, comprising: an AC voltage interface (11) designed to be coupled to a power supply network (2); a battery interface (12) designed to be coupled to a traction battery (3) of an electric vehicle; a charging circuit (13) designed to convert an electrical voltage provided at the AC voltage interface (11) into a further voltage suitable for charging the traction battery (3); and a monitoring device (10) according to one of claims 1 to 7.

9. Charging device (1) according to claim 8, wherein the charging circuit (13) is further designed to receive an electrical signal provided at the battery interface (12). To convert DC voltage into a single-phase or multi-phase AC voltage and to provide the AC voltage at the AC interface (11).

10. A method for monitoring a charging device (1) for an electric vehicle, comprising the steps: Determining (S1) a first power flow at an AC interface (11) of the charging device (1); determining (S2) a second power flow at a battery interface (12) of the Loading device (1); Calculating (S3) an efficiency of the charging device (1) using a comparison of the first power flow and the second power flow; and Detecting (S4) a malfunction of the charging device (1) if the calculated efficiency of the charging device (1) deviates from a current nominal efficiency of the charging device (1) by more than a predetermined threshold value.

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