Bidirectional charging device for an electrically operated vehicle, charging system, and method for operating such a charging device

Abstract

The invention relates to a bidirectional charging device for an electrically operated vehicle, wherein the charging device is designed to charge an electrical energy store of the electrically operated vehicle via a charging connection and to discharge said energy store at least via the charging connection. According to the invention, the charging device is designed such that an insulation fault, in which at least one potential of the primary side and at least one potential of the secondary side unintentionally come into contact with each other, is detected between the primary-side DC-to-DC converter part (18) and the secondary-side DC-to-DC converter part (22) by the charging device in the discharge operating mode, and the charging device is designed to carry out, in the event of a detected insulation fault, a safety function in which at least one action is carried out, the charging device being operated while the action is carried out such that coupling elements between the primary-side DC-to-DC converter part and the secondary-side DC-to-DC converter part are diagnosed, whereby at least one intact coupling element of the coupling elements is determined, and electrical energy present on the primary side is discharged to the secondary side or is consumed via the at least one intact coupling element. The invention further relates to a corresponding method for operating such a bidirectional charging device for an electrically operated vehicle.

Description

[0001] Description

[0002] Bidirectional charging device for an electrically powered vehicle, charging system and method for operating such a charging device

[0003] The invention relates to a bidirectional charging device for an electrically powered vehicle such as a plug-in electric vehicle, abbreviated PEV (English: “plug-in electric vehicle”), preferably for a battery electric vehicle, abbreviated BEV (English: “battery electric vehicle”).

[0004] Furthermore, the invention relates to a charging system with such a charging device and a method for operating such a charging device.

[0005] Bidirectional charging devices for battery electric vehicles are widely known from the prior art and are conventionally referred to as On-Board Chargers (OBCs), i.e., chargers on board electric vehicles which are used to charge the battery and to supply, for example, external AC consumers with the electrical energy provided by the battery (so-called "Vehicle to Load" operation, or "V2L" for short).

[0006] Such charging devices in the form of on-board chargers (OBCs) for electric vehicles ensure that the vehicle's electrical energy storage system or battery, for example in the form of a high-voltage energy storage system or a high-voltage battery, is charged and discharged safely and efficiently.

[0007] Traditionally, the OBC converts alternating current (AC) from an external power source, such as the AC grid, into direct current (DC), which is used to charge the battery.

[0008] Typically, an on-board computer (OBC) for an electric vehicle includes an AC input (alternating current input), for example, in the form of an AC connection such as an AC charging socket, an input filter, a power converter that can operate bidirectionally as an inverter or rectifier (e.g., a PFC circuit), a DC-DC converter, an output filter, and a DC output. The AC input connects to an external power source, such as the AC mains or an external AC load, and is often provided in the form of the conventional charging socket on electric vehicles.

[0009] The input filter is designed to suppress electromagnetic interference (EMI) and also ensures that the OBC complies with legal requirements.

[0010] The power converter connected to the input filter operates as a rectifier during the charging mode of the OBC, converting the incoming alternating current (AC) into pulsating direct current (DC). During discharge mode, however, the power converter operates as an inverter, converting the direct current supplied by the battery into alternating current, which can then be fed to an external AC load.

[0011] The DC-DC converter with galvanic isolation converts the pulsating direct current from the rectifier into a constant direct voltage suitable for charging the battery. The galvanic isolation between the input network (i.e., the AC mains) and the battery increases safety and allows for voltage adjustments.

[0012] For the purposes of this disclosure, the side of the OBC that is connected to the AC power grid up to the galvanic isolation point is referred to as the primary side of the OBC. Conversely, the side of the OBC extending from the galvanic isolation point to the electrical energy storage device is referred to as the secondary side of the OBC.

[0013] The output filter smooths the output voltage and reduces noise and ripple, and the DC output forms a connection to the electric vehicle's battery.

[0014] To operate the aforementioned components of the charging device, specifically the on-board computer (OBC), a control and monitoring unit is typically provided. This unit monitors and controls the charging and discharging processes and is designed for communication with other communication units in the vehicle, such as via CAN bus. The control and monitoring unit continuously monitors the battery's state of charge and adjusts the corresponding charging and discharging parameters to the OBC's operating mode. Simultaneously, it communicates with the external infrastructure and the vehicle management system. This monitoring and control system provides protection against overcurrent, overvoltage, short circuits, and overheating of the OBC.

[0015] Traditionally, an OBC is also equipped with a "DC Link" or intermediate circuit with one or more intermediate circuit capacitors on its primary side.

[0016] The DC link in an OBC (Optical Base Station) forms a circuit that stabilizes the DC voltage and acts as an interface between the AC-DC and DC-DC conversions. The function of the DC link on the primary side of the OBC is to smooth out or stabilize ripples that occur during the AC-DC conversion; that is, small, periodic fluctuations or ripples in the DC voltage or current resulting from the conversion of alternating current (AC) to direct current (DC).

[0017] The smoothed DC voltage from the DC link is then passed on to the DC-DC converter. The DC link thus supplies the DC-DC converter with a stable DC voltage and contributes to the efficiency and performance of the system.

[0018] In conventional charging devices in the form of such OBCs, so-called insulation faults in the form of an insulation breakdown in the galvanic isolation of the DC-DC converter can occur, which can lead to a temporary overvoltage on the OBC primary side.

[0019] For example, a method for detecting such an insulation fault is known from the prior art publication DE 10 2022 210 539 A1.

[0020] In the event of such an insulation fault, an active discharge circuit is usually triggered on the primary side of the OBC to eliminate or at least largely reduce potential risks to persons (e.g., electric shock) and to electrical equipment of the OBC or related equipment (e.g., thermal disturbance).

[0021] Such an active discharge circuit typically includes at least one switch, e.g., an AC relay or semiconductor switch, as well as several relatively large discharge resistors to dissipate the relatively large amount of energy that may be stored in the DC link, i.e., the intermediate circuit capacitors, in the event of such an insulation fault on the primary side of the OBC.

[0022] However, implementing a resistor-based active discharge circuit requires increased installation space within the vehicle, which contradicts the requirements of increasingly limited vehicle installation space. Consequently, accommodating such on-board chargers (OBCs) with active discharge circuits in ever-shrinking vehicle spaces is problematic and requires adaptation, particularly in terms of design.

[0023] The invention is therefore based on the objective of further developing the generic charging devices and methods for operating such charging devices in such a way that, in the event of an insulation fault between the primary and secondary sides, damage to components of the charging device can be largely avoided; preferably, requirements for a small installation space for the accommodation of the charging device as well as corresponding safety devices to prevent damage to components of the charging device in the event of an insulation fault in the vehicle are to be taken into account.

[0024] This task is solved by the characteristics of independent claims.

[0025] Advantageous embodiments and further developments of the invention result from the dependent claims.

[0026] According to a first aspect, the invention is characterized by a bidirectional charging device. The bidirectional charging device according to the invention is intended for an electrically powered vehicle, preferably a battery electric vehicle (BEV), and is configured to charge and discharge an electrical energy storage device, preferably a high-voltage energy storage device, of the electrically powered vehicle via a charging port. The charging device has a primary side and a secondary side, the primary side being connectable to the charging port, which is connectable to an external AC power source or to an external load that can be operated with AC power, in order to charge the energy storage device via the connected external AC power source or to discharge the energy storage device via the connected external load.and the secondary side is connectable to the energy storage device. The primary side comprises a power converter having an input side electrically connectable to the charging port and an output side, and is configured to operate in a first mode as a rectifier and in a second mode as an inverter, wherein the power converter is configured to convert an AC voltage applied to its input side into a DC voltage applied to its output side in the first mode, and to convert a DC voltage applied to its output side into an AC voltage applied to its input side in the second mode, and a primary-side DC-DC converter section of a DC-DC converter with galvanic isolation, which is electrically connected to the output side of the power converter.preferably via an intermediate circuit with one or more intermediate circuit capacitors. The secondary side comprises a secondary-side DC-DC converter section of the DC-DC converter, which is galvanically isolated from the primary-side DC-DC converter section, wherein the primary-side DC-DC converter section and the secondary-side DC-DC converter section are configured to perform DC-DC conversion between the primary and secondary sides in the first or second operating mode, wherein the charging device is configured to operate in a charging mode in which the vehicle's energy storage device is charged via the charging port from the external AC power source, and in a discharging mode in which the energy storage device is discharged via the charging port to supply energy to the external load or via a further port to supply energy to another AC-operable load.The charging device is configured to detect an insulation fault between the primary-side DC-DC converter section and the secondary-side DC-DC converter section during discharge operation, in which at least one potential of the primary side and at least one potential of the secondary side unintentionally come into contact with each other. The charging device is therefore further configured to perform a safety function upon detection of an insulation fault by carrying out at least one first action and / or one second action and / or one third action, preferably in the aforementioned order.

[0027] In particular, during the first action, the charging device is operated in such a way that it shuts down. Therefore, no further control of components of the charging device, such as the power converter or the DC-DC converter, takes place, and the charging device ceases operation.

[0028] Furthermore, the charging device is operated, particularly during the second action, in such a way that a diagnosis of coupling elements between the primary-side DC-DC converter part and the secondary-side DC-DC converter part is carried out, whereby at least one intact coupling element of the coupling elements is identified, and that electrical energy present on the primary side is transferred to the secondary side or consumed via the at least one intact coupling element.

[0029] Determining whether one or more coupling elements are intact is useful because activating a defective or non-intact coupling element can cause a thermal event in the charging device, which can result in a total failure of the charging device or the OBC.

[0030] Furthermore, the charging device is operated in such a way, particularly during the third action, that discharge can take place via a passive discharge circuit arranged in the primary-side DC-DC converter section.

[0031] According to the invention, the galvanic isolation between the primary and secondary sides of the charging device or the OBC is continuously monitored during discharge operation (vehicle-to-load operation) based on criteria explained in more detail below. If an insulation fault is detected, the first, second, and / or third actions are then initiated, preferably in the order mentioned, to prevent damage to components of the charging device.

[0032] The charging device according to the invention differs from the aforementioned prior art in particular in that no dedicated active discharge circuit is required, as described above. Instead, in the event of an insulation fault or breakdown between the primary and secondary sides of the charging device according to the invention or the OBC, the existing DC-DC converter or DC voltage converter or its intact coupling elements are used to transfer the energy on the primary side back to the secondary side in the HV battery area.

[0033] The coupling elements of the DC-DC converter are primarily so-called DC-DC banks, which are designed to transfer energy from the primary side to the secondary side and vice versa. For this purpose, each coupling element incorporates a transformer circuit that provides galvanic isolation between the primary and secondary sides, or between the primary and secondary sides of the DC-DC converter, and enables energy transfer via magnetic coupling between the two sides. The coupling elements are operated, for example, by their associated switches.

[0034] The bidirectional charging device according to the invention can advantageously be further developed in such a way that, when performing the first action, the charging device is operated in such a way that the power converter is switched off, in particular a power factor correction filter circuit forming the power converter is switched off, and / or a defective coupling element of the coupling elements identified during the diagnosis is switched off.

[0035] Furthermore, the bidirectional charging device according to the invention can be implemented in such a way that, when carrying out the second action, the charging device is operated in such a way that an intermediate circuit capacitor, which is connected in an intermediate circuit between the converter and the galvanic isolation, in particular between the converter and the primary-side DC-DC converter part, is discharged via the intact coupling element.

[0036] Furthermore, the bidirectional charging device according to the invention can be implemented such that, when performing the second action, the charging device is operated in such a way that electrical energy is discharged from the primary side to the secondary side via the intact coupling element or is consumed as reactive power by operating the DC-DC converter using the intact coupling element, and / or a complete decoupling of the charging port from the energy storage device is carried out in order to disconnect the energy storage device from the external AC power source or external load connected to the charging port.

[0037] Furthermore, the bidirectional charging device according to the invention can be designed such that, when performing the third action, the charging device is operated in such a way that discharge is enabled via one or more resistors of a passive discharge circuit, which are connected in parallel to the intermediate circuit capacitor of the intermediate circuit.

[0038] Furthermore, the bidirectional charging device according to the invention can be configured such that the charging device is set up to perform the first action within 1 second of detecting the insulation fault and / or is set up to perform the second action within 5 seconds of detecting the insulation fault and / or to perform the third action after a period of 5 seconds has elapsed since detecting the insulation fault.

[0039] Furthermore, the bidirectional charging device according to the invention can be implemented in such a way that the charging device is configured to detect the insulation fault, namely for example on the basis of detectable quantities and parameters, as described in the prior art document DE 10 2022 210 539 A1.

[0040] In particular, an insulation fault is detected if one or more of the following conditions are met for a specific debounce time, preferably in a range between 100ms and 400ms, in particular exactly 100ms or 200ms or 300ms or 400ms:

[0041] - a voltage rise rate or slope of a voltage curve detected by a monitoring device, in particular an insulation monitor, between at least one alternating current potential (e.g. L1, L2 or L3 potential) and chassis or a neutral conductor potential and chassis (protective conductor potential) exceeds a threshold value,

[0042] - A current measured at one of the coupling elements of the DC-DC converter is outside a predetermined range, i.e., there is a deviation between the target and actual current that exceeds a predetermined limit; - A timeout in the communication between the primary and secondary sides is detected, where the timeout could be, for example, a period of time exceeding a limit during which a microcontroller on one side, e.g., the primary side, and a communication counterpart, such as another microcontroller, on the other side, e.g., the secondary side, communicate.

[0043] - a diagnosis reveals an exceedance of a measured voltage or current range that bridges the galvanic isolation between the primary and secondary sides, or an implausible operating condition such as a "stuck high / low" state.

[0044] Furthermore, the bidirectional charging device according to the invention can be further developed such that the charging device is configured to detect an insulation fault between the primary-side DC-DC converter section and the secondary-side DC-DC converter section during the discharge operation, in which at least a partial discharge of the energy storage device occurs via the secondary-side DC-DC converter section towards the primary-side DC-DC converter section, caused by a short circuit of a switch of the secondary-side DC-DC converter section, in particular by a

[0045] This is triggered by a gate-drain short circuit of a high-side MOSFET in the secondary-side DC-DC converter section. Specifically, this involves a switch associated with a coupling element, i.e., a defective coupling element.

[0046] Furthermore, the bidirectional charging device according to the invention can be designed such that the DC voltage converter is configured to perform a voltage adjustment in the charging mode by converting the voltage on the primary side into a voltage with a higher or lower voltage level on the secondary side.

[0047] According to a second aspect, the invention is characterized by a charging system. The charging system according to the invention is intended for an electrically powered vehicle, preferably a battery-electric vehicle, and comprises the bidirectional charging device according to the invention, a charging port connected to the primary side of the charging device, and an electrical energy storage device connected to the secondary side of the charging device. The properties and advantages described in the first aspect relating to the charging device according to the invention are thus achieved in the same or a similar way, which is why, to avoid repetition, reference is made to the preceding descriptions relating to the charging device according to the invention.

[0048] According to a third and fourth aspect, the invention is characterized by a method and a corresponding control unit for operating a bidirectional charging device. The method and the control unit according to the invention are provided for operating a bidirectional charging device for an electrically powered vehicle, in particular the charging device according to the invention, wherein the charging device is configured to charge an electrical energy storage device of the electrically powered vehicle via a charging port and to discharge it at least via the charging port, wherein the charging device has a primary side and a secondary side, the primary side being connectable to the charging port, which is connectable to an external AC power source or to an external load that can be operated with AC.to charge the energy storage device via the connected external AC power source or to discharge the energy storage device via the connected external load, and the secondary side is connectable to the energy storage device, wherein the primary side comprises a power converter having an input side electrically connectable to the charging port and an output side, and is configured to operate in a first mode as a rectifier and in a second mode as an inverter, wherein the power converter is configured to convert an AC voltage applied to its input side into a DC voltage applied to its output side in the first mode, and to convert a DC voltage applied to its output side into an AC voltage applied to its input side in the second mode, a primary-side DC-DC converter section of a DC-DC converter with galvanic isolation,which is electrically connected to the output side of the converter, wherein the secondary side comprises a secondary-side DC-DC converter section of the DC-DC converter, which is galvanically isolated from the primary-side DC-DC converter section and is electrically connectable to the energy storage device, wherein the primary-side DC-DC converter section and the secondary-side DC-DC converter section are configured to perform DC-DC conversion between the primary side and the secondary side in the first or second operating mode, wherein the charging device is configured to operate in a charging mode in which the vehicle's energy storage device is charged via the charging port from the external AC power source, and in a discharging mode.in which the energy storage device is discharged via the charging port to supply energy to the external load or via another port to supply energy to another load that can be operated with alternating current, wherein the charging device is configured to detect an insulation fault between the primary-side DC-DC converter part and the secondary-side DC-DC converter part during the discharge operation, in which at least one potential of the primary side and at least one potential of the secondary side unintentionally come into contact with each other, wherein the charging device is operated in such a way that, in the event of a detected insulation fault, a safety function is executed by performing at least one action, in particular a second action, preferably after performing a first action and / or before performing a third action, wherein the action is performed in such a manner thatthat a diagnosis of coupling elements is carried out between the primary-side DC-DC converter section and the secondary-side DC-DC converter section, whereby at least one intact coupling element is identified, and that electrical energy present on the primary side is transferred to the secondary side or consumed via the at least one intact coupling element.

[0049] This results in the same or similar properties and advantages for the method and the control unit as described in connection with the charging device according to the invention, which is why reference is made to the preceding explanations in connection with the charging device according to the invention in order to avoid repetition.

[0050] A preferred embodiment of the invention is explained below by way of example with reference to Figure 1.

[0051] Figure 1 shows a schematic representation of a charging system according to the invention, comprising a bidirectional charging device 10 according to the invention for an electrically powered vehicle, which in this exemplary embodiment is formed by a plug-in electric vehicle (PEV), and a charging port 14 and an electrical energy storage device 24. The bidirectional charging device 10 according to the invention forms an on-board charger (OBC) of the PEV, i.e., it is a bidirectional charger located on board the PEV, via which an energy storage device 24, such as a battery (in this case, a high-voltage electrical energy storage device of the PEV), can be charged and discharged. In particular, the charging device 10 is configured to charge and discharge the energy storage device 24, in the form of the high-voltage energy storage device of the electrically powered vehicle, via a charging port 14.

[0052] The charging port 14 is designed as a conventional charging socket and can be connected to an external alternating current source such as the alternating current grid (AC grid, alternating current domain) or to an external load or AC consumer or load that can be operated with alternating current (AC load) in order to either charge the energy storage device 24 via the connected external alternating current source or to discharge the energy storage device 24 via the connected external load.

[0053] The charging device 10 according to the invention has a primary side and a secondary side. The primary side of the charging device 10 is electrically connected to the charging port 14. The secondary side of the charging device 10, on the other hand, is electrically connected to the energy storage device 24. As will be explained in more detail below, the primary side and the secondary side of the charging device 10 are isolated from each other by a galvanic isolation 21 of a DC-DC converter 20, thereby ensuring electrical isolation between the two sides.

[0054] The primary side of the charging device 10 has a bidirectional power converter 16, which has an input side electrically connected to the charging port 14 and an output side, and is configured to operate in a first mode as a rectifier and in a second mode as an inverter. In particular, the power converter 16 is formed by a conventional PFC (Power Factor Correction) circuit known from the prior art, or by a power factor correction filter, in particular an active PFC circuit.

[0055] The power converter 16 is configured to convert an alternating voltage applied to its input side into a direct voltage applied to its output side in the first operating mode, operating as a rectifier, and to convert a direct voltage applied to its output side into an alternating voltage applied to its input side in the second operating mode, operating as an inverter.

[0056] Furthermore, the charging device 10 according to the invention has a DC voltage converter 20 with galvanic isolation 21, wherein the DC voltage converter 20 is electrically connected to the power converter 16, in particular its output side, via a conventional intermediate circuit 70 with one or more intermediate circuit capacitors.

[0057] In particular, the DC-DC converter 20 comprises a primary-side DC-DC converter part 18 in the primary side of the charging device 10 and a secondary-side DC-DC converter part 22 in the secondary side of the charging device 10, wherein in particular the primary-side DC-DC converter part 18 is connected to the intermediate circuit 70.

[0058] The secondary side of the charging device 10 thus has the secondary-side DC-DC converter section 22 of the DC-DC converter 20, which is galvanically separated or isolated from the primary-side DC-DC converter section 18 via the galvanic isolation 21, wherein the primary-side DC-DC converter section 18 and the secondary-side DC-DC converter section 22 are configured to perform a DC-DC conversion between the primary side and the secondary side in the first or second operating mode, namely via coupling elements 30, 32, 34, which are only schematically indicated in Fig. 1 and which are explained in more detail below.

[0059] The coupling elements 30, 32, 34, in this embodiment so-called high-voltage DC-DC banks, of the DC-DC converter 20 are configured to transfer energy from the primary side to the secondary side and vice versa. For this purpose, the coupling elements 30, 32, 34 each have a transformer circuit that provides galvanic isolation between the primary and secondary sides, or between the primary-side DC-DC converter section 18 and the secondary-side DC-DC converter section 22, and enables energy transfer between the two sides via magnetic coupling. Accordingly, the coupling elements 30, 32, 34 first convert the DC voltage supplied by the converter 16 into an AC voltage and, after energy transfer from the primary side to the secondary side, convert it back into a regulated DC voltage via the transformer circuit.The energy transfer is monitored by a control unit with a microcontroller or a dedicated control IC, which is described in more detail below, and regulates the power of the converter to ensure stable output conditions.

[0060] In particular, the control unit regulates and monitors the primary and secondary switches (transistors) of the respective coupling elements 30, 32, 34. For example, these switches, e.g. in the form of MOSFETs, high-voltage MOSFETs or IGBTs, control the energy transfer from a primary winding of the transformer circuit to a secondary winding of the transformer circuit by means of their control by the control unit, whereby the respective coupling elements 30, 32, 34 on the secondary side ensure the rectification of the output voltage via the respective switches and diodes.

[0061] The energy storage device 24 is electrically connected to the secondary-side DC converter part 22 and is designed to be charged or discharged via the secondary-side DC converter part 22.

[0062] Thus, the charging device 10 according to the invention can be operated in a charging mode in which the energy storage device 24 of the vehicle is charged via the charging port 14 from the external AC power source, and in a discharging mode in which the energy storage device 24 is discharged via the charging port 14 to supply energy to the external load or via a further port 60 to supply energy to another load that can be operated with AC power.

[0063] For example, the additional connection could be a socket or a protective contact socket located in the rear of the vehicle, which supplies, for example, an alternating voltage of 230 V to charge external devices such as an AC power supply for a notebook.

[0064] Furthermore, the charging device 10 according to the invention comprises the aforementioned control unit or monitoring device 50, which is configured to detect an insulation fault between the primary-side DC-DC converter section 18 and the secondary-side DC-DC converter section 22 in a respective coupling element 30, 32, 34 during discharge operation and to initiate appropriate measures or safety functions. The regular operation of the charging device 10 according to the invention, i.e., when no fault such as an insulation fault occurs, proceeds, for example, as follows: In the charging mode of the charging device 10, in which the vehicle's energy storage device 24 is charged via the charging port 14 from the external AC power source, such as the AC mains, the converter operates in its first operating mode as a rectifier and converts the current at the charging port 14 into a DC-DC converter.It converts the alternating voltage applied to its input side into a direct voltage applied to its output side.

[0065] This DC voltage is supplied to the primary-side DC-DC converter section 18 via the intermediate circuit 70 to perform a DC-DC conversion. Specifically, in charging mode, the DC-DC converter 18 performs voltage adjustment by converting the voltage at the primary-side DC-DC converter section 18 on the primary side into a voltage with a higher or lower voltage level at the secondary-side DC-DC converter section 22 on the secondary side; the respective energy transfer via the galvanic isolation is carried out via the respective coupling elements 30, 32, 34.

[0066] Preferably, the DC-DC converter 20 provides a voltage on the secondary side that can be either higher (e.g., a DC voltage up to 900 V) or lower (e.g., 450 V DC) than the voltage on the primary side; for example, the DC voltage at the intermediate circuit capacitor of the intermediate circuit 70 on the primary side is constant at 800 V.

[0067] Based on the adapted DC voltage at the secondary-side DC voltage converter part 22, the energy storage device 24 can be charged with the provided adapted DC voltage.

[0068] In a discharge mode of the charging device 10, in which the energy storage device 24 is discharged via the charging port 14 to supply energy to the external load or via the additional port 60 to supply energy to another AC-operated load, the DC-DC converter 20 performs the voltage adaptation from the secondary-side DC-DC converter section 22 to the primary-side DC-DC converter section 18, and the converter 16 is operated as an inverter in the second operating mode such that a DC voltage applied to its output side is converted into an AC voltage applied to its input side. The converted AC voltage can then be made available at the charging port 14 or the additional port 60.

[0069] The operation of the charging device 10 according to the invention in the event of a fault, i.e., when an insulation fault occurs, is, for example, as follows: During the operation of the charging device 10 according to the invention, in particular in its discharge mode, the control device or monitoring device 50 detects the insulation fault between the primary-side DC-DC converter part 18 and the secondary-side DC-DC converter part 22, in which at least a partial discharge of the energy storage device 24 occurs via the secondary-side DC-DC converter part 22 towards the primary-side DC-DC converter part 18.

[0070] For example, the galvanic isolation 21 of the DC-DC converter 20 fails with respect to one of the coupling elements 30, 32, 34, so that a breakdown occurs at the defective location of the galvanic isolation 21 or a conductive connection between the primary side and secondary side of the DC-DC converter 20 via the defective coupling element, for example in the case of an insulation fault of an isolated gate driver of a switch associated with the respective coupling element.

[0071] In particular, during discharge operation, an insulation fault can occur between the primary-side DC-DC converter section 18 and the secondary-side DC-DC converter section 22 via a defective coupling element, in which at least partial discharge of the energy storage device 24 occurs via the secondary-side DC-DC converter section 22 towards the primary-side DC-DC converter section 18 via the defective coupling element, namely due to a short circuit of a switch of the secondary-side DC-DC converter section 22 associated with the coupling element, in particular due to a gate-drain short circuit of a high-side MOSFET of the secondary-side DC-DC converter section 22 associated with the coupling element.

[0072] Of course, other causes for an insulation breakdown in the galvanic isolation 21 of the DC-DC converter 20 are also possible. For example, the galvanic isolation 21 may be affected by aging effects, or an insulation barrier may be damaged due to a short circuit (high energy input) near this insulation barrier between the primary and secondary sides of the DC-DC converter 20.

[0073] This can lead to the situation where a potential of the energy storage device 24 on the secondary side, i.e., a potential of the high-voltage energy storage device, is unintentionally present on the primary side.

[0074] The detection of the insulation fault is carried out by the control or monitoring device 50, in particular by the control or monitoring device 50 concluding that an insulation fault has occurred when one or more of the following conditions are met for a specific debounce time; the debounce time in this context is a so-called "debouncing time," i.e., a delay time introduced to filter out unwanted rapid changes or disturbances in signals that could originate from mechanical switches, relays, or other electrical contacts in the charging device in the form of the OBC. This type of disturbance is often referred to as "bounce." The debouncing time is in the range between 100 ms and 400 ms, specifically 100 ms, 200 ms, 300 ms, or 400 ms. The respective conditions are as follows:

[0075] - a voltage rise rate or slope of a voltage curve detected by a control and monitoring device 50 between at least one AC potential (e.g. L1, L2 or L3 potential) and chassis or a neutral conductor potential and chassis (protective conductor potential) exceeds a threshold value,

[0076] - a current measured at one of the coupling elements 30, 32, 34 of the DC voltage converter 20 is outside a predetermined range, i.e., there is a deviation between the target and actual current that exceeds a predetermined limit value.

[0077] - A timeout in relation to communication between the primary and secondary sides is detected, where the timeout can be, for example, a period of time exceeding a limit during which a microcontroller on one side, e.g., the primary side, and a communication counterpart, such as another microcontroller, on the other side, e.g., the secondary side, communicate.

[0078] - A diagnosis reveals an exceedance of a measured voltage or current range that bridges the galvanic isolation between the primary and secondary sides, or an implausible operating condition such as a "stuck high / low" state. Upon detection of an insulation fault, the control or monitoring device 50 is configured to execute a safety function by performing at least a first action, a second action, and a third action in the specified sequence, as described in detail below:

[0079] The first action is performed upon detection of the insulation fault within one second (1 s) of the detection of the insulation fault and includes a shutdown of the charging device 10 as such, i.e. the operation of the charging device 10 is stopped.

[0080] In particular, the power converter 16, which in this embodiment is at least partially formed by a power factor correction filter circuit or PFC circuit, is switched off. The control of the PFC circuit, including its shutdown, is carried out, for example, by the control unit or monitoring unit 50, which can be a microcontroller or a dedicated PFC controller.

[0081] Furthermore, a diagnostic step is performed to identify a defective coupling element among coupling elements 30, 32, 34 of the DC-DC converter 20. The defective coupling element is then deactivated or no longer controlled, thus functioning as a pulse blocker. The deactivation of the defective coupling element can also be carried out by the control or monitoring unit 50, for example, by activating switches associated with the defective coupling element.

[0082] In the aforementioned fault case (gate-drain short circuit of a high-side MOSFET associated with the coupling element of the secondary-side DC-DC converter part 22), a fast pulse blocking within a few ps is absolutely necessary to avoid a thermal event in the affected coupling element (HV / HV-DCDC bank on the secondary side (i.e. in the HV battery area)).

[0083] The first action thus pursues the objective of reducing the voltage in the intermediate circuit 70 as quickly as possible to a voltage level below 60 V DC within 1 s, i.e., below a predefined temporary overvoltage range. This allows passive discharge resistors on the primary side, for example at the charging terminal 14, to discharge the voltage to below 60 V DC within one second.

[0084] The second action is performed within five seconds (5s) of the detection of an insulation fault and comprises diagnosing the coupling elements 30, 32, 34 of the galvanic isolation between the primary-side DC-DC converter section 18 and the secondary-side DC-DC converter section 22 in order to identify at least one intact coupling element. The identified intact coupling element is then controlled by the control unit 50 to dissipate or consume electrical energy via the intact coupling element. Specifically, the intact coupling element is controlled such that the electrical energy present on the primary side is dissipated or consumed via the at least one identified intact coupling element on the secondary side, for example, in the energy storage device 24.

[0085] In particular, when carrying out the second action, the charging device 10 is operated in such a way that the intermediate circuit capacitor, which is arranged in the intermediate circuit 70 between the primary DC-DC converter part 18 of the DC-DC converter 20 and the power converter 16, is discharged via the intact coupling element of the coupling elements 30, 32, 34; this is accomplished, for example, by controlling the respective switches assigned to the intact coupling element accordingly.

[0086] In this embodiment, the charging device 10 is preferably operated during the second action in such a way that electrical energy is discharged from the primary side to the secondary side via the intact coupling element of the coupling elements 30, 32, 34, or is consumed as reactive power by operating the DC voltage converter 18 using the intact coupling element of the coupling elements 30, 32, 34.

[0087] Furthermore, in addition to the aforementioned shutdown, the charging port 14 is completely decoupled from the energy storage device 24 in order to disconnect or isolate the energy storage device 24 from the external AC power source or external load connected to the charging port 14. This second action is intended to prevent any short-term overvoltage occurring within a period of less than 5 seconds after the insulation fault is detected. The still-intact coupling element, identified through appropriate diagnostics, is controlled accordingly to discharge the DC link capacitor located on the primary side to the lowest possible voltage, for example, reducing it from a voltage level of 800 V DC to a voltage level in the range of 200 V DC to 300 V DC. The energy is thus transferred to the energy storage device 24, i.e.,The high-voltage energy storage device, in the form of the HV battery (battery domain), is relocated to eliminate the overvoltage condition on the primary side of the charging device. For this purpose, a discharge to a voltage level below 60 V DC is not necessary, which would not be feasible with an HV / HV-DC-DC converter. However, a discharge to a voltage level in the range of 200 V to 300 V DC is sufficient to eliminate the overvoltage condition between the primary-side HV potentials and the chassis (the sum of a Cy-Cap voltage on the secondary side of the charging device and the DC link voltage on the primary side of the charging device should be less than 550 V DC; i.e., a long-term, temporary overvoltage should be avoided).

[0088] The third action is carried out after a period of 5 seconds has elapsed since the detection of the insulation fault and involves operating the primary-side DC-DC converter section 18 in such a way that discharge can occur via a passive discharge circuit arranged in the primary-side DC-DC converter section 18 or in the intermediate circuit 70. The discharge takes place via one or more resistors of the discharge circuit, which is designed as a passive discharge circuit and in which the resistor(s) are connected in parallel to the intermediate circuit capacitor of the intermediate circuit 70. This largely prevents any long-term, temporary overvoltage.

[0089] The features of the invention disclosed in the foregoing description, in the drawings and in the claims may be essential for the realization of the invention, either individually or in any combination.

Claims

Patent claims 1. Bidirectional charging device (10) for an electrically powered vehicle, wherein the charging device (10) is configured to charge an electrical energy storage device (24) of the electrically powered vehicle via a charging port (14) and to discharge it at least via the charging port (14), wherein the charging device (10) has a primary side and a secondary side, wherein the primary side is connectable to the charging port (14), which is connectable to an external AC power source or to an external load operable with AC power in order to charge the energy storage device (24) via the connected external AC power source or to discharge the energy storage device (24) via the connected external load, and the secondary side is connectable to the energy storage device (24), wherein the primary side comprises a power converter (16) which has an input side and an output side electrically connectable to the charging port (14) and is configuredto be operated in a first operating mode as a rectifier and in a second operating mode as an inverter, wherein the converter (16) is configured to convert an AC voltage applied to its input side into a DC voltage applied to its output side in the first operating mode, and to convert a DC voltage applied to its output side into an AC voltage applied to its input side in the second operating mode, a primary-side DC-DC converter section (18) of a DC-DC converter (20) with galvanic isolation (21) which is electrically connected to the output side of the converter (16), wherein the secondary side comprises a secondary-side DC-DC converter section (22) of the DC-DC converter (20) which is separated from the primary-side DC-DC converter section (18) via the galvanic isolation (21),wherein the primary-side DC-DC converter part (18) and the secondary-side DC-DC converter part (22) are configured to perform DC-DC conversion between the primary and secondary sides in the first or second operating mode, wherein the charging device (10) is configured in a charging mode in which the vehicle's energy storage device (24) is charged via the charging port (14) from the external AC power source, and in a discharging mode, in which, the energy storage device is discharged via the charging port to supply energy to the external load or via another port to supply energy to another load that can be operated with alternating current, wherein the charging device (10) is configured to detect an insulation fault between the primary-side DC-DC converter section (18) and the secondary-side DC-DC converter section (22) during the discharge operation, in which at least one potential of the primary side and at least one potential of the secondary side unintentionally come into contact with each other, wherein the charging device (10) is configured to perform a safety function when an insulation fault is detected by performing at least one action, in particular a second action, preferably after performing a first action and / or before performing a third action, wherein the charging device (10) is operated in such a manner when performing the action,that a diagnosis of coupling elements (30, 32, 34) is carried out between the primary-side DC-DC converter part (18) and the secondary-side DC-DC converter part (22), whereby at least one intact coupling element of the coupling elements (30, 32, 34) is identified, and that electrical energy present on the primary side is transferred to the secondary side or consumed via the at least one intact coupling element.

2. Bidirectional charging device (10) according to claim 1, wherein the charging device (10) is configured to perform a safety function in the event of a detected insulation fault by performing at least a first action, preferably before performing the second action, wherein the charging device (10) is operated in such a way as to shut down the charging device (10) when performing the first action.

3. Bidirectional charging device (10) according to claim 1 or 2, wherein the charging device (10) is configured to perform a safety function in the event of a detected insulation fault by performing at least a third action, preferably after performing the first and / or second action, wherein the charging device (10) is operated in such a way during the third action that a discharge can take place via a passive discharge circuit (40) arranged in the primary-side DC-DC converter part (18).

4. Bidirectional charging device (10) according to claim 2 or 3, wherein the charging device (10) is operated during the first action in such a way that the power converter (16) is switched off and / or A defective coupling element of the coupling elements (30, 32, 34) identified during the diagnosis is switched off.

5. Bidirectional charging device (10) according to one of claims 1 to 4, wherein the charging device (10) is operated during the second action in such a way that an intermediate circuit capacitor, which is connected in an intermediate circuit (70) between the converter (16) and the galvanic isolation (21), is discharged via the intact coupling element.

6. Bidirectional charging device (10) according to any one of claims 1 to 5, wherein the charging device (10) is operated during the second action in such a way that electrical energy is discharged from the primary side to the secondary side via the intact coupling element or is consumed as reactive power by operating the DC-DC converter (20) using the intact coupling element, and / or a complete decoupling / separation of the charging port (14) from the energy storage device (24) is carried out in order to disconnect the energy storage device (24) from the external AC power source or external load connected to the charging port (14).

7. Bidirectional charging device (10) according to one of the preceding claims 3 to 6, wherein the charging device (10) is operated during the third action in such a way that discharge is enabled via one or more resistors of a passive discharge circuit, which are connected in parallel to the intermediate circuit capacitor of the intermediate circuit (70).

8. Bidirectional charging device (10) according to one of the preceding claims, wherein the charging device (10) is configured to perform the first action within 1 second of the detection of the insulation fault and / or is configured to perform the second action within 5 seconds of the detection of the insulation fault and / or to perform the third action after a period of 5 seconds has elapsed since the detection of the insulation fault.

9. Bidirectional charging device (10) according to one of the preceding claims, wherein the charging device (10) is configured during the to detect an insulation fault between the primary-side DC-DC converter section (18) and the secondary-side DC-DC converter section (20) during discharge operation, in which at least a partial discharge of the energy storage device (24) occurs via the secondary-side DC-DC converter section (22) to the primary-side DC-DC converter section (18), which is triggered by a short circuit of a switch of the secondary-side DC-DC converter section (22), in particular by a gate-drain short circuit of a high-side MOSFET of the secondary-side DC-DC converter section (22).

10. Bidirectional charging device (10) according to one of the preceding claims, wherein the DC-DC converter (18) is configured to perform voltage adjustment in charging mode by converting the voltage on the primary side into a voltage with a higher or lower voltage level on the secondary side.

11. Charging system for an electrically powered vehicle comprising a bidirectional charging device (10) according to one of the preceding claims, a charging port (14) connected to the primary side of the charging device (10) and an electrical energy storage device (24) connected to the secondary side of the charging device (10).

12. Method for operating a bidirectional charging device (10) for an electrically powered vehicle, in particular a charging device (10) according to any one of claims 1 to 9, wherein the charging device (10) is configured to charge an electrical energy storage device (24) of the electrically powered vehicle via a charging port (14) and to discharge it at least via the charging port (14), wherein the charging device (10) has a primary side and a secondary side, wherein the primary side is connectable to the charging port (14), which is connectable to an external AC power source or to an external load operable with AC power in order to charge the energy storage device (24) via the connected external AC power source or to discharge the energy storage device (24) via the connected external load, and the secondary side is connectable to the energy storage device (24), wherein the primary side comprises a power converter (16) having an input side electrically connectable to the charging port (14) and an output side, and configured to operate in a first mode as a rectifier and in a second mode as an inverter, wherein the power converter (16) is configured to convert an AC voltage applied to its input side into a DC voltage applied to its output side in the first mode, and to convert a DC voltage applied to its output side into an AC voltage applied to its input side in the second mode, a primary-side DC-DC converter section (18) of a DC-DC converter (20) with galvanic isolation (21) which is electrically connected to the output side of the power converter (16), wherein the secondary side comprises a secondary-side DC-DC converter section (22) of the DC-DC converter (20),which is separated from the primary-side DC-DC converter section (18) via the galvanic isolation (21) and is electrically connectable to the energy storage device (21), wherein the primary-side DC-DC converter section (18) and the secondary-side DC-DC converter section (22) are configured to perform a DC-DC conversion between the primary and secondary sides in the first or second operating mode, wherein the charging device (10) is configured to operate in a charging mode in which the vehicle's energy storage device (24) is charged via the charging port (14) from the external AC power source, and in a discharging mode in which the energy storage device is discharged via the charging port to supply energy to the external load or via a further port to supply energy to another AC-operable load, wherein the charging device (10) is configuredto detect an insulation fault between the primary-side DC-DC converter section (18) and the secondary-side DC-DC converter section (22) during the discharge operation, in which at least one potential of the primary side and at least one potential of the secondary side unintentionally come into contact with each other, wherein the charging device (10) is operated such that, in the event of a detected insulation fault, a safety function is executed by performing at least one action, in particular a second action, preferably after performing a first action and / or before performing a third action, wherein the action is performed in such a way that a diagnosis of coupling elements (30, 32, 34) between the primary-side, DC voltage converter part (18) and the secondary-side DC voltage converter part (22) is carried out, whereby at least one intact coupling element of the coupling elements (30, 32, 34) is determined, and that electrical energy present on the primary side is carried away to the secondary side or consumed via the at least one intact coupling element.

13. Control device (50) for operating a bidirectional charging device (10) for an electrically powered vehicle, wherein the charging device (10) is configured to charge an electrical energy storage device (24) of the electrically powered vehicle via a charging port (14) and to discharge it at least via the charging port (14), wherein the charging device (10) has a primary side and a secondary side, wherein the primary side is connectable to the charging port (14), which is connectable to an external AC power source or to an external load operable with AC power in order to charge the energy storage device (24) via the connected external AC power source or to discharge the energy storage device (24) via the connected external load, and the secondary side is connectable to the energy storage device (24), wherein the primary side comprises a power converter (16),the converter (16) has an input side electrically connectable to the charging port (14) and an output side and is configured to be operated in a first operating mode as a rectifier and in a second operating mode as an inverter, wherein the converter (16) is configured to convert an AC voltage applied to its input side into a DC voltage applied to its output side in the first operating mode, and to convert a DC voltage applied to its output side into an AC voltage applied to its input side in the second operating mode, a primary-side DC-DC converter section (18) of a DC-DC converter (20) with galvanic isolation (21) which is electrically connected to the output side of the converter (16), wherein the secondary side comprises a secondary-side DC-DC converter section (22) of the DC-DC converter (20),which is separated from the primary-side DC-DC converter part (18) via the galvanic isolation (21) and can be electrically connected to the energy storage device (21), wherein the primary-side DC-DC converter section (18) and the secondary-side DC-DC converter section (22) are configured to perform DC-DC conversion between the primary and secondary sides in the first or second operating mode, wherein the charging device (10) is configured to operate in a charging mode in which the vehicle's energy storage device (24) is charged via the charging port (14) from the external AC power source, and in a discharging mode in which the energy storage device is discharged via the charging port to supply energy to the external load or via another port to supply energy to another AC-operable load, wherein the charging device (10) is configured to detect an insulation fault between the primary-side DC-DC converter section (18) and the secondary-side DC-DC converter section (22) during the discharging mode.to detect at least one potential of the primary side and at least one potential of the secondary side unintentionally coming into contact with each other, wherein the control device is configured to operate the charging device (10) in such a way that, in the event of a detected insulation fault, a safety function is executed by performing at least one action, in particular a second action, preferably after performing a first action and / or before performing a third action, wherein the action is performed in such a way that a diagnosis of coupling elements (30, 32, 34) between the primary-side DC-DC converter part (18) and the secondary-side DC-DC converter part (22) is carried out, whereby at least one intact coupling element of the coupling elements (30, 32, 34) is identified, and that electrical energy present on the primary side is discharged to the secondary side or consumed via the at least one intact coupling element.

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