Method and control unit for operating a charging unit for a vehicle

Abstract

Method and device for operating a charging unit (100) having electromechanical switching elements (S1, S2, S3, S5, S6), wherein a faulty element of the electromechanical switching elements (S1, S2, S3, S5, S6) in the charging unit (100) is detected based on a current determined by means of one of the current sensors (A1, A2, A3, A5) and a voltage determined by means of one of the voltage sensors (U1, U2, U3), and a fault signal is generated upon detection of a faulty electromechanical switching element (S1, S2, S3, S5, S6).

Description

[0001] R. 416584

[0002] - 1 -

[0003] Description

[0004] title

[0005] Procedures and for the operation of a for a

[0006] The invention relates to a method and a control unit for operating a charger. Furthermore, the invention relates to a powertrain with a corresponding control unit and a vehicle with a powertrain, as well as a computer program and a machine-readable storage medium.

[0007] State of the art

[0008] Onboard chargers for electric vehicles are a known technology. These chargers are designed to provide charging current to an energy storage device integrated into the vehicle for the electric drive, using electrical energy from an external AC voltage source. Newer chargers also offer the option of supplying AC voltage via an external or internal socket connection in the vehicle, or via a socket for a standard electrical appliance, using energy from the energy storage device. This operation is also known as vehicle-to-load (V2L) operation. For the safe operation of a charger, electrically controlled electromechanical switching elements or relays are used, which are located between the connections to the AC voltage source and the actual charging circuitry of the charger.Such electromechanical switching elements or relays are also preferably used between the connections to the socket and the actual charging circuit of the charger. For the safe operation of a charger, a diagnostic check of the relays' functionality is essential. Most relays have a signal contact, a so-called feedback line, through which information about the R. 416584 is transmitted.

[0009] - 2 -

[0010] The functionality of a relay is provided. Due to the desire to reduce interfaces, required circuit board space, and costs, there is a need for alternative methods for identifying faulty relays in a vehicle charger.

[0011] Disclosure of the invention

[0012] A procedure for operating a charger for a vehicle is provided.

[0013] The charger comprises, on the input side, a multi-phase input connection unit with phase conductor connections and a neutral conductor connection for connecting a power source. An input connection unit is preferably a socket or configured to accept a plug for a connecting or charging cable for electrically connecting the charger to a power source, preferably an external AC power source. Preferably, the input connection unit includes at least one phase conductor connection for transmitting the AC voltage via a phase conductor and a neutral conductor connection for transmitting the potential of a neutral conductor connection via a neutral conductor, in order to connect the charger and / or the charging circuit to an AC power source via the input connection unit. On the output side, the charger comprises a two-pole output connection unit for connecting an energy storage device to be charged.Preferably, the output terminal unit is designed to be connected to an energy storage device, preferably a DC power source such as a rechargeable battery, a standard battery, or a high-voltage battery. Between the input terminal unit and the output terminal unit, the charger includes a charging circuit. On the input side, towards the input terminal unit, the charging circuit comprises a first converter circuit. Preferably, this first converter circuit is a controllable inverter or a controllable power factor correction (PFC) circuit configured to provide a DC output voltage from an AC input voltage. On the output side, i.e., towards the output terminal unit, the charging circuit comprises a second converter circuit.Preferably, this second converter circuit is a controllable DC-DC converter configured to provide a DC voltage at the output from a DC voltage applied at the input. The first and second converter circuits are connected via a DC voltage converter R. 416584.

[0014] - 3 - DC link connected to each other. A DC link voltage is applied to the DC link, preferably between an upper potential and a lower potential of the DC link. Furthermore, the DC link comprises a series connection of two capacitors, so-called DC link capacitors, between the upper and the lower potential of the DC link (170). A center tap is arranged between these capacitors. The at least one phase conductor and one neutral conductor of the input connection unit are each connected to the charging circuit of the charger via an electromechanical switching element and a subsequent current sensor. Preferably, electromechanical switching elements are designed as contactors or relays.The charger has at least one voltage sensor between the input terminal unit and the electromechanical switching elements to determine the voltage between at least one phase conductor and the neutral conductor. The center tap is connected to the neutral conductor terminal of the input terminal unit via another electromechanical switching element. The procedure comprises the following steps:

[0015] Detecting a faulty electromechanical switching element in the charger based on a current measured by one of the current sensors; outputting an error signal after detecting a faulty electromechanical switching element; preferably terminating operation or the charging process and bringing the charger to a safe state. Preferably, the operation is a vehicle-to-load operation, preferably providing an AC voltage at a (preferably additional) socket connection or at the input connection unit, preferably via at least one phase conductor and the neutral conductor, to supply a load to be connected or already connected. Preferably, the current sensors determine whether a current flows from or into the charging circuit after a change in the switching state of at least one electromechanical switching element.Preferably, depending on the measured current, it is detected before and / or after the change in the switching state whether one of the electromechanical switching elements is faulty, i.e., permanently closed or permanently open, or whether it is functioning as intended. Preferably, the voltage sensors determine the magnitude, rate of change, or rate of change (gradient) of a voltage at the input terminal unit or at the DC link after a change in the switching state of at least one electromechanical switching element. Preferably, depending on the measured voltage, before and / or after the change of R. 416584.

[0016] - 4 -

[0017] The switching state is detected to determine whether one of the electromechanical switching elements is faulty, i.e., permanently closed or permanently open, or whether it is functioning as intended. Preferably, an error signal is output upon detection of a faulty electromechanical switching element. Preferably, the output of an error signal includes the transmission of corresponding information to a logic unit or a controller inside or outside the control unit, so that an appropriate response to the detected error occurs and / or a notification is sent to the user. This preferably serves to inform the user and also to control fault mode of the charger and / or the vehicle, preferably to control the termination of the charger's operation or the charging process and / or to bring the charger into a safe state.Preferably, bringing the device into a safe state includes opening the switchable connections of the charger to the energy sources or energy storage devices and discharging any existing DC link capacitors so that the touch voltage of the charger is minimized.

[0018] Advantageously, a method is provided for the safe operation of a charger with electromechanical switching elements. For this purpose, sensors already present in the charger are used to detect faulty electromechanical switching elements.

[0019] In one embodiment, the charger includes a voltage sensor between the upper and lower potentials of the DC link for determining the DC link voltage, and a voltage sensor between the center tap and the lower potential of the DC link for determining the capacitor voltage. Detection of the faulty electromechanical switching element is based on the capacitor voltage or the DC link voltage, preferably on a gradient of the capacitor voltage or a gradient of the difference between the DC link voltage and the capacitor voltage.

[0020] Advantageously, an improved and extended method is provided for the safe operation of a charger with electromechanical switching elements. For this purpose, sensors already present in the charger are used to detect faulty electromechanical switching elements. R. 416584

[0021] - 5 -

[0022] In one embodiment, the first converter circuit is preferably configured as a PFC stage. The first converter circuit has an input inductor for each phase conductor and neutral conductor. Each input inductor is connected to a half-bridge center tap of one half-bridge of the first converter circuit. Preferably, each input inductor is connected on one side to a terminal of one of the current sensors of the phase conductors or the neutral conductor and on the other side to a half-bridge center tap of one of the half-bridges of each phase conductor or neutral conductor of the first converter circuit. Each half-bridge of the converter circuit comprises a series connection of a high-side and a low-side switching element. The series connections are connected between the upper and lower potentials of the DC link.Each half-bridge center tap is further connected to a switching element that blocks current in both directions, the other terminal of which is connected to the center tap. Preferably, a switching element that blocks current in both directions is a bidirectionally blocking switching element. Preferably, a bidirectionally blocking switching element is formed from two series-connected semiconductor switching elements, e.g., MOSFETs, IGBTs, or SICs, whose body diodes are oriented in opposite directions.

[0023] Advantageously, a circuit topology for the first converter circuit is provided for an improved, extended method for the safe operation of a charger with electromechanical switching elements. The method utilizes sensors already present in the charger to detect faulty electromechanical switching elements.

[0024] In one embodiment, the detection of a faulty electromechanical switching element comprises the following steps: opening the electromechanical switching elements; receiving an input signal indicating that no power source is connected to the input terminal unit; subsequently pre-charging the DC link using the second converter circuit, particularly in reverse operation; closing the high-side switching elements of the half-bridges of the first converter circuit connected to the phase conductors; determining the charging currents using the current sensors of the phase conductors; determining the voltages using the voltage sensors; detecting a faulty electromechanical switching element when a determined charging current exceeds a predefined R. 416584

[0025] - 6 -

[0026] The current threshold is exceeded if a measured voltage exceeds a predefined voltage threshold or if the gradient of the difference between the DC link voltage and the capacitor voltage exceeds a predefined gradient threshold. Preferably, the electromechanical switching element is detected as permanently closed.

[0027] Preferably, to open an electromechanical switching element, it is controlled accordingly via a control unit, preferably a control device, and a signal line. Preferably, an input signal indicating that no power source is connected to the input terminal is received, rather than a signal from the power source, for example, an external charger or a charging station. Alternatively, a signal from the vehicle indicating that a driving mode is active can be used to infer that no power source is connected. Likewise, as an alternative, when the electromechanical switching element is open, the voltage sensors of the charger can determine the voltages present at the input terminal between the phase conductors and the neutral conductor.As long as the measured voltages are below a predefinable threshold, it is concluded that no power source, preferably an AC power source, is connected to the input terminal. This AC power source is preferably an external charger configured for charging, or more preferably for transferring, electrical energy to an energy storage device that can be connected to the charger. Preferably, the DC link, more preferably the series connection of the two capacitors, is first charged or pre-charged with energy from the connectable energy storage device by operating, more preferably by reverse operation, the second converter circuit. Preferably, the DC link is charged to a predefinable voltage. The voltage level is selected so that sufficient energy is available to carry out the subsequent process or diagnostic steps.Preferably, to close a high-side switching element, it is controlled accordingly via a control unit, preferably a control device, and a signal line. Despite the voltage gradient from the DC link via the first converter circuit towards the input terminal unit, the open electromechanical R. 416584.

[0028] - 7 - Switching elements do not detect any charging currents through the phase conductor current sensors. Likewise, no voltages result between the phase conductors and the neutral conductor. Since the DC link does not discharge, no relevant gradient of the difference between the DC link voltage and the capacitor voltage results. A faulty electromechanical switching element is detected when the described behavior does not occur and thus a relevant charging current, voltage, or gradient of the difference between the DC link voltage and the capacitor voltage is detected by the described sensors. These general explanations of the method also apply to the following embodiments or configurations.

[0029] Advantageously, a more detailed procedure is provided for the safe operation of a charger with electromechanical switching elements. For this purpose, sensors already present in the charger are used to detect faulty electromechanical switching elements.

[0030] In one embodiment, the detection of the faulty electromechanical switching element comprises the following steps: pre-charging the DC link using the second converter circuit, particularly in reverse operation; closing the electromechanical switching elements of the phase conductors and opening the electromechanical switching elements of the neutral conductor and the center tap; closing the high-side switching elements of the half-bridges of the first converter circuit connected to the phase conductors; determining the charging currents using the current sensors of the phase conductors; determining the voltages using the voltage sensors;Detecting a faulty electromechanical switching element when a measured charging current exceeds a predefined current threshold, when a measured voltage exceeds a predefined voltage threshold, or when the gradient of the difference between the intermediate circuit voltage and the capacitor voltage exceeds a predefined gradient threshold.

[0031] Preferably, to close an electromechanical switching element, it is controlled accordingly via a control unit, preferably a control device, and a signal line. This embodiment also results in R. 416584

[0032] - 8 - Due to the open electromechanical switching elements, preferably the neutral conductor and the center tap, no charging currents pass through the current sensors of the phase conductors. Likewise, no voltages result between the phase conductors and the neutral conductor. Since the DC link does not discharge, no relevant gradient of the difference between the DC link voltage and the capacitor voltage results. A faulty electromechanical switching element, in particular a permanently closed electromechanical switching element of the center tap, is detected when the described behavior does not occur and thus a relevant charging current, voltage, or a relevant gradient of the difference between the DC link voltage and the capacitor voltage is detected by the described sensors. These general explanations of the method also apply to the following embodiments or configurations.

[0033] Advantageously, a more detailed procedure is provided for the safe operation of a charger with electromechanical switching elements. For this purpose, sensors already present in the charger are used to detect faulty electromechanical switching elements.

[0034] In one embodiment, the detection of the faulty electromechanical switching element comprises the following steps: pre-charging the DC link using the second converter circuit, particularly in reverse operation; opening the electromechanical switching elements of the phase conductors, the neutral conductor, and the center tap; closing the high-side switching elements of the half-bridges of the first converter circuit connected to the phase conductors; closing the electromechanical switching element of the center tap; determining the charging currents using the current sensors of the phase conductors; determining the voltages using the voltage sensors;Detection of a faulty electromechanical switching element when a measured charging current exceeds a predefined current threshold, when a measured voltage exceeds a predefined voltage threshold, or when the gradient of the difference between the intermediate circuit voltage and the capacitor voltage exceeds a predefined gradient threshold. R. 416584;

[0035] - 9 -

[0036] Even in this configuration, due to the open electromechanical switching elements of the phase conductors and despite the closed electromechanical switching element of the center tap, no charging currents result through the current sensors of the phase conductors. Likewise, no voltages result between the phase conductors and the neutral conductor. Since the DC link does not discharge, no relevant gradient of the difference between the DC link voltage and the capacitor voltage results. A faulty electromechanical switching element, in particular a permanently closed electromechanical switching element of the phase conductors, is detected when the described behavior does not occur and thus a relevant charging current, voltage, or gradient of the difference between the DC link voltage and the capacitor voltage is detected by the described sensors.These general explanations of the procedure also apply to the following exemplary embodiments or configurations.

[0037] Advantageously, a more detailed procedure is provided for the safe operation of a charger with electromechanical switching elements. For this purpose, sensors already present in the charger are used to detect faulty electromechanical switching elements.

[0038] In one embodiment, the detection of the faulty electromechanical switching element comprises the following steps: pre-charging the DC link using the second converter circuit, particularly in reverse operation; closing the electromechanical switching elements of the phase conductors and the center tap; closing the high-side switching elements of the half-bridges of the first converter circuit connected to the phase conductors; determining the charging currents using the current sensors of the phase conductors; determining the voltages using the voltage sensors;Detection of a faulty electromechanical switching element when a measured charging current falls below a predefinable current threshold, when the difference between the DC link voltage and the capacitor voltage and a measured phase voltage exceeds a predefinable threshold, or when the gradient of the difference between the DC link voltage and the capacitor voltage falls below a predefinable gradient threshold. R. 416584;

[0039] - 10 -

[0040] In this configuration, the closed electromechanical switching elements of the phase conductors and the closed electromechanical switching element of the center tap result in charging currents through the current sensors of the phase conductors. Consequently, voltages also arise between the phase conductors and the neutral conductor. Since the DC link also discharges as a result, a significant gradient in the difference between the DC link voltage and the capacitor voltage also results.A faulty electromechanical switching element, in particular a permanent opening of one of the electromechanical switching elements of the phase conductors or the center tap, is detected if the described behavior does not occur and it is thus determined by means of the described sensors that there is no relevant charging current, that a difference between the DC link voltage and the capacitor voltage and a determined phase voltage exceeds a predefinable threshold, or that the gradient of the difference between the DC link voltage and the capacitor voltage falls below a predefinable gradient threshold.

[0041] Advantageously, a more detailed procedure is provided for the safe operation of a charger with electromechanical switching elements. For this purpose, sensors already present in the charger are used to detect faulty electromechanical switching elements.

[0042] In one embodiment, the detection of a faulty electromechanical switching element comprises the following steps: pre-charging the DC link using the second converter circuit, particularly in reverse operation; opening the high-side switching elements of the half-bridges of the first converter circuit connected to the phase conductors; opening the electromechanical switching elements of the phase conductors and the center tap; closing the low-side switching elements of the half-bridges of the first converter circuit connected to the phase conductors and the bidirectional blocking switching elements connected to the center point of the neutral conductor half-bridge; determining the charging currents using the current sensors of the phase conductors; determining the voltages using the voltage sensors; detecting a faulty electromechanical switching element when a determined charging current exceeds a predefined value. R. 416584

[0043] - 11 -

[0044] The current threshold is exceeded if a measured voltage exceeds a predefinable voltage threshold or if the gradient of the difference between the intermediate circuit voltage and the capacitor voltage exceeds a predefinable gradient threshold.

[0045] Preferably, a high-side switching element is opened by means of a control unit and a signal line. Similarly, a low-side switching element is closed by means of a control unit and a signal line. Even in this configuration, due to the open electromechanical switching elements of the phase conductors, the open high-side switching elements, and despite the closed low-side switching elements of the half-bridges of the first converter circuit (150) connected to the phase conductors and the closed bidirectional blocking switching element connected to the midpoint of the neutral conductor's half-bridge, no charging currents result through the current sensors of the phase conductors. Likewise, no voltages result between the phase conductors and the neutral conductor.Since the DC link does not discharge, no relevant gradient of the difference between the DC link voltage and the capacitor voltage results. A faulty electromechanical switching element, in particular a permanently closed electromechanical switching element of the phase conductors or the center tap, is detected when the described behavior does not occur and thus a relevant charging current, voltage, or gradient of the difference between the DC link voltage and the capacitor voltage is determined by the described sensors. These general explanations of the method also apply to the following embodiments or configurations.

[0046] Advantageously, a more detailed procedure is provided for the safe operation of a charger with electromechanical switching elements. For this purpose, sensors already present in the charger are used to detect faulty electromechanical switching elements. R. 416584

[0047] - 12 -

[0048] In one embodiment, the detection of the faulty electromechanical switching element comprises the following steps: pre-charging the DC link using the second converter circuit, particularly in reverse operation; closing the electromechanical switching elements of the phase conductors; closing the low-side switching elements of the half-bridges of the first converter circuit connected to the phase conductors and of the switching element connected to the midpoint of the neutral conductor's half-bridge, which blocks current in both directions; determining the charging currents using the current sensors of the phase conductors; determining the voltages using the voltage sensors;Detecting a faulty electromechanical switching element when a measured charging current exceeds a predefined current threshold, when a measured voltage exceeds a predefined voltage threshold, or when the gradient of the difference between the intermediate circuit voltage and the capacitor voltage exceeds a predefined gradient threshold.

[0049] In this configuration, due to the closed electromechanical switching elements of the phase conductors and the closed low-side switching elements, and the bidirectional blocking switching element connected to the midpoint of the neutral conductor's half-bridge, no charging currents result through the phase conductor current sensors. Consequently, no voltages arise between the phase conductors and the neutral conductor. Since the DC link also does not discharge, a significant gradient results in the difference between the DC link voltage and the capacitor voltage.A faulty electromechanical switching element, in particular a permanently closed electromechanical switching element of the neutral conductor, is detected if the described behavior does not occur and thus a measured charging current exceeds a predefinable current threshold, if a measured voltage exceeds a predefinable voltage threshold, or if the gradient of the difference between the intermediate circuit voltage and the capacitor voltage exceeds a predefinable gradient threshold.

[0050] Advantageously, a more detailed procedure for the safe operation of a charger with electromechanical switching elements is provided. See R. 416584.

[0051] - 13 - the sensor technology already present in the charger is used to detect faulty electromechanical switching elements.

[0052] In one embodiment, the detection of the faulty electromechanical switching element comprises the following steps: pre-charging the DC link using the second converter circuit, particularly in reverse operation; closing the electromechanical switching elements of the phase conductors and the neutral conductor; closing the low-side switching elements of the half-bridges of the first converter circuit connected to the phase conductors and of the bidirectional blocking switching element connected to the midpoint of the neutral conductor half-bridge; determining the charging currents using the current sensors of the phase conductors; determining the voltages using the voltage sensors;Detecting a faulty electromechanical switching element when a measured charging current falls below a predefined current threshold, when the sum of a measured voltage and the negative capacitor voltage exceeds a predefined voltage threshold, or when the gradient of the capacitor voltage falls below a predefined gradient threshold.

[0053] In this configuration, due to the closed electromechanical switching elements of the phase conductors and the neutral conductor, as well as the closed low-side switching elements of the half-bridges of the first converter circuit connected to the phase conductors, and the closed switching element connected to the midpoint of the neutral conductor's half-bridge, which blocks current in both directions, charging currents result through the current sensors of the phase conductors. Voltages also result between the phase conductors and the neutral conductor. Since the DC link consequently discharges, a significant gradient of the capacitor voltage also results.A faulty electromechanical switching element, in particular a permanently open electromechanical switching element of the neutral conductor, is detected if the described behavior does not occur and thus a measured charging current falls below a predefinable current threshold, if the sum of a measured voltage and the negative capacitor voltage exceeds a predefinable voltage threshold, or if the gradient of the capacitor voltage falls below a predefinable gradient threshold. R. 416584.

[0054] - 14 -

[0055] These general explanations of the procedure also apply to the following exemplary embodiments or configurations.

[0056] Advantageously, a more detailed procedure is provided for the safe operation of a charger with electromechanical switching elements. For this purpose, sensors already present in the charger are used to detect faulty electromechanical switching elements.

[0057] Furthermore, the invention relates to a control unit for operating a charger, wherein the control unit is configured to control the charger in such a way that one of the described methods is carried out. Preferably, the control unit comprises a logic unit, preferably for detecting a faulty electromechanical switching element, preferably depending on components of the charger controlled via outputs by means of signals and measured values ​​received via inputs according to the previous description, and preferably for outputting an error signal, and preferably for terminating the operation of the charger or the charging process, and preferably for bringing the charger into a safe state. Advantageously, a control unit is provided which enables the safe operation of a charger with electromechanical switching elements.

[0058] Furthermore, the invention relates to a powertrain for a vehicle, wherein the powertrain comprises at least one control unit and a charger, and preferably an energy storage device. Such a powertrain serves, for example, to propel an electric vehicle. The method and the control unit enable safe operation of the powertrain.

[0059] Furthermore, the invention relates to a vehicle with a described drive train. Advantageously, a vehicle is thus provided which includes a control unit that ensures the safe operation of a charger.

[0060] Furthermore, the invention relates to a computer program comprising commands that cause the control unit to execute the described process steps. R. 416584

[0061] - 15 -

[0062] Furthermore, the invention relates to a machine-readable storage medium comprising instructions which, when executed by a control unit, cause it to perform the described process steps.

[0063] It is understood that the features, properties and advantages of the method according to the invention apply accordingly to the control unit, or the drive train and the vehicle and vice versa.

[0064] Further features and advantages of embodiments of the invention will become apparent from the following description with reference to the accompanying drawings.

[0065] Brief description of the drawing

[0066] The invention will be explained in more detail below using some figures, including:

[0067] Figure 1 shows a schematic representation of a charger,

[0068] Figure 2 shows a schematic representation of a vehicle with a drivetrain and a charger.

[0069] Figure 3 shows a schematic representation of a method for operating a charger.

[0070] Embodiments of the invention

[0071] Figure 1 shows a charger 100. The charger 100 comprises, on the input side, a multi-phase input connection unit 110 with phase conductor connections Lx and a neutral conductor connection N for connecting a (not shown) energy source. On the output side, the charger comprises a two-pole output connection unit 120 for connecting an energy storage device 130 to be charged. The energy storage device is preferably a high-voltage battery or an R. 416584

[0072] - 16 -

[0073] A traction battery for powering the vehicle, supplying the vehicle's electric drive with electrical energy. A charging circuit 140 is arranged between the input terminal unit 110 and the output terminal unit 120. The charging circuit 140 comprises a first converter circuit 150 on the input side and a second converter circuit 160 on the output side. Preferably, the first converter circuit is designed to be connected to alternating current (AC) on the input side and direct current (DC) on the output side. Preferably, the first converter circuit 150 is an inverter or a power factor correction (PFC) stage. Preferably, the first converter circuit is bidirectional, meaning that electrical energy can be transferred from the input side to the output side of the first converter circuit and vice versa, depending on the control signal.The first and second converter circuits are connected to each other via a DC link 170. A DC link voltage is present at the DC link 170. Preferably, the charger 100 includes a DC link voltage sensor Uzk at the DC link for determining the electrical voltage between the upper and lower potentials of the DC link. Preferably, the DC link 170 includes a series connection of two capacitors C1 and C2 between the upper and lower potentials, with a center tap M between them. Preferably, the first and second capacitors have the same capacitance. Preferably, the charger 100 includes a voltage sensor Uk at the DC link between the center tap and the lower potential of the DC link 170 for determining a capacitor voltage.The first converter circuit 150 preferably comprises, on the input side, a choke or inductor for each phase conductor and the neutral conductor, each of which is connected to a half-bridge center tap of each half-bridge of the first converter circuit 150. The half-bridges are preferably connected in series as two semiconductor switching elements, a high-side switching element and a low-side switching element, between the upper and lower potentials of the DC link. The half-bridge center taps are each connected to the center tap via a bidirectionally blocking semiconductor switching element. The second converter circuit 160 preferably comprises a bidirectionally operable DC-DC converter circuit, preferably with galvanic isolation. For example, the second converter circuit is R. 416584.

[0074] - 17 -

[0075] The second converter circuit 160 is configured by means of an input-side primary-side active full bridge, a transformer, and a secondary-side output-side active full bridge, preferably as a dual active bridge (DAB) DC-DC converter circuit. The second converter circuit 160 can preferably be operated in forward or reverse mode, wherein in forward mode energy is transferred from the input-side DC link 170 towards the output-side connectable energy storage device 130, and in reverse mode energy is transferred from the connectable energy storage device 130 towards the input-side DC link 170. Preferably, in reverse mode, the DC link of the second converter circuit 160 is pre-charged.Preferably, in forward operation of the second converter circuit 160, the connectable energy storage device is charged, preferably by discharging the DC link 170, preferably while the electromechanical switching elements of the phase conductors are open. The phase conductors Lx and a neutral conductor N of the input connection unit 110 are each connected to the charging circuit 140 via an electromechanical switching element S1, S2, S3, S5 and a subsequent current sensor A1, A2, A3, A5. Furthermore, the charger 100 comprises voltage sensors U1, U2, U3 between the input connection unit 110 and the electromechanical switching elements S1, S2, S3, S5 for determining the electrical voltages, preferably AC voltages, between the phase conductors Lx and the neutral conductor N. The center tap M is connected to the neutral conductor terminal N of the input connection unit 110 via another electromechanical switching element S6.A control unit 105 is provided and configured to control the charger 100 for operation in a vehicle. Preferably, the control includes the targeted control of at least one of the electromechanical switching elements S1, S2, S3, S5, S6, the semiconductor switching elements, the bidirectional blocking semiconductor switching elements, the first and second converter circuits depending on the current and voltage values ​​read from the current and voltage sensors.

[0076] Figure 2 shows a schematic representation of a vehicle 400 with a drive train 300. The drive train 300 comprises at least one control unit 105 and R. 416584

[0077] - 18 - a charger 100. Preferably, the drive train further comprises an energy storage device 130, an inverter 180, and / or an electric machine 190. The control unit 105 is preferably shown in Figure 2 as part of the charger 100. Likewise, the control unit 105 can also be arranged outside the charger 100. For this purpose, the control unit 105 would preferably be connected to the charger 100 via appropriate communication means, so that information exchange and control are ensured. The illustration shows an example of a four-wheeled vehicle, whereby the invention can be used equally in any vehicle with any number of wheels on land, water, and in the air.

[0078] Figure 3 shows a schematic sequence of a method 200 for operating a charger for a vehicle 400. The method starts with step 210. In step 230, a faulty electromechanical switching element Sx in the charger 100 is detected as a function of a current measured by one of the current sensors Ax and a voltage measured by one of the voltage sensors Ux. Subsequently, in step 240, an error signal F is output after the detection of a faulty electromechanical switching element Sx.Preferably, in step 250, the charging process is terminated, preferably by opening the electromechanical switching elements, the semiconductor switching elements and / or the bidirectionally blocking semiconductor switching elements of the charger 100, and / or the charger 100 is brought into a safe state, preferably by discharging the DC link capacitors by forward operation of the second converter circuit 160 or preferably by opening the electromechanical switching elements, the semiconductor switching elements and / or the bidirectionally blocking semiconductor switching elements of the charger 100. The method ends with step 260.

[0079] As described above, the procedure preferably includes further steps for detecting the faulty electromechanical switching element.

Claims

R. 416584 - 19 - Claims 1. Method (200) for operating a charger, with a charger (100), wherein the charger (100) comprises on the input side a multi-phase input terminal unit (110) with phase conductor terminals (Lx) and a neutral conductor terminal (N) for connecting a power source, and on the output side a two-pole output terminal unit (120) for connecting an energy storage device (130) to be charged, between the input terminal unit (110) and the output terminal unit (120) comprises a charging circuit (140), wherein the charging circuit (140) comprises on the input side a first converter circuit (150) and on the output side a second converter circuit (160), which are connected to each other via a DC link (170), wherein a DC link voltage is applied to the DC link (170), wherein the DC link (170) comprises a series connection of two capacitors (C1, C2) between an upper and a lower potential of the DC link (170), between which a center tap (M) is arranged, wherein phase conductors (Lx) and a neutral conductor (N) of the input terminal unit (110) are each connected to the charging circuit (140) via an electromechanical switching element (S1, S2, S3, S5) and a subsequent current sensor (A1, A2, A3, A5), wherein the charger (100) is connected between the input terminal unit (110) and the electromechanical switching elements (S1 , S2, S3,S5) comprises voltage sensors (U1, U2, U3) for determining the voltages between the phase conductors (Lx) and the neutral conductor (N), wherein the center tap (M) is connected via a further electromechanical switching element, (S6) is connected to the neutral conductor terminal (N), using the following steps: Detection (230) of a faulty electromechanical switching element (Sx) in R. 416584 - 20 - the charger (100) depending on a current determined by means of one of the current sensors (Ax) and a voltage determined by means of one of the voltage sensors (Ux); Output (240) of an error signal (F) after detection of a faulty electromechanical switching element (Sx).

2. Method according to claim 1, wherein the charger (100) comprises a voltage sensor (Uzk) between the upper and lower potentials of the DC link (170) for determining the DC link voltage and a voltage sensor (Uk) between the center tap and the lower potential of the DC link (170) for determining a capacitor voltage; wherein the detection (230) of the faulty electromechanical switching element (Sx) is carried out as a function of the capacitor voltage or the DC link voltage, preferably as a function of a gradient of the capacitor voltage, or a gradient of a difference between the DC link voltage and the capacitor voltage.

3. Method according to claim 2, wherein the first converter circuit (150) has an input choke on the input side for each phase conductor (Lx) and neutral conductor (N), wherein each input choke is connected to a half-bridge center tap of each half-bridge of the first converter circuit (150), wherein each half-bridge comprises a series connection of a high-side and a low-side switching element, wherein the series connections are connected between the upper and the lower potential of the DC intermediate circuit (170), wherein each half-bridge center tap is connected to a switching element that blocks current in both directions, the other terminal of which is connected to the center tap. R. 416584 - 21 - 4. Method according to claim 3, wherein the detection (230) of the faulty electromechanical switching element comprises the steps: Opening (212) the electromechanical switching elements (Sx), receiving (213) an input signal (SE) indicating that no power source is connected to the input terminal unit (110), Subsequently, pre-charging (216) of the DC intermediate circuit (170) by means of the second converter circuit (160), especially in reverse operation; Closing (218) the high-side switching elements of the half-bridges connected to the phase conductors of the first converter circuit (150); Determine (220) the charging currents using the current sensors (Ax) of the phase conductors; Determine (221) the voltages using the voltage sensors (Ux); Detect (226) a faulty electromechanical switching element (Sx) when a measured charging current exceeds a predefinable current threshold, when a measured voltage exceeds a predefinable voltage threshold, or when the gradient of the difference between the intermediate circuit voltage and the capacitor voltage exceeds a predefinable gradient threshold.

5. Method according to claim 3 or 4, wherein the detection (230) of the faulty electromechanical switching element comprises the steps: Precharging (216) of the DC intermediate circuit (170) by means of the second converter circuit (160), especially in reverse operation; Closing (217_1 ) of the electromechanical switching elements of the phase conductors (S1 , S2, S3) and opening (217_2) of the electromechanical switching elements of the neutral conductor (S5) and the center tap (S6); Closing (218) the high-side switching elements of the half-bridges connected to the phase conductors of the first converter circuit (150); Determine (220) the charging currents using the current sensors (Ax) of the phase conductors; Determine (221) the voltages using the voltage sensors (Ux); Detect (226) a faulty electromechanical switching element (Sx) when a measured charging current exceeds a predefinable current threshold, when a measured voltage exceeds a predefinable voltage threshold R. 416584 - 22 - or if the gradient of the difference between the intermediate circuit voltage and the capacitor voltage exceeds a predefinable gradient threshold.

6. Method according to claim 3 or 4, wherein the detection (230) of the faulty electromechanical switching element comprises the steps: Precharging (216) of the DC intermediate circuit (170) by means of the second converter circuit (160), especially in reverse operation; Opening (217_3) of the electromechanical switching elements of the phase conductors (S1 , S2, S3), the neutral conductor (S5) and the center tap (S6); Closing (218) the high-side switching elements of the half-bridges connected to the phase conductors of the first converter circuit (150); Closing (218_1) of the electromechanical switching element of the center tap (S6); Determine (220) the charging currents using the current sensors (Ax) of the phase conductors; Determine (221) the voltages using the voltage sensors (Ux); Detect (226) a faulty electromechanical switching element (Sx) when a measured charging current exceeds a predefinable current threshold, when a measured voltage exceeds a predefinable voltage threshold, or when the gradient of the difference between the intermediate circuit voltage and the capacitor voltage exceeds a predefinable gradient threshold.

7. Method according to claim 3 or 4, wherein the detection (230) of the faulty electromechanical switching element comprises the steps: Precharging (216) of the DC intermediate circuit (170) by means of the second converter circuit (160), especially in reverse operation; Closing (217_4) of the electromechanical switching elements of the phase conductors (S1 , S2, S3) and the center tap (S6); Closing (218) the high-side switching elements of the half-bridges connected to the phase conductors of the first converter circuit (150); Determine (220) the charging currents using the current sensors (Ax) of the phase conductors; Determine (221) the voltages using the voltage sensors (Ux); R. 416584 - 23 - Detect (227) a faulty electromechanical switching element (Sx) when a determined charging current falls below a predefinable current threshold, when a difference between the difference of the intermediate circuit voltage and the capacitor voltage and a determined phase voltage exceeds a predefinable threshold, or when the gradient of the difference between the intermediate circuit voltage and the capacitor voltage falls below a predefinable gradient threshold.

8. Method according to claim 3 or 4, wherein the detection (230) of the faulty electromechanical switching element comprises the steps: Precharging (216) of the DC intermediate circuit (170) by means of the second converter circuit (160), especially in reverse operation; Opening (219) the high-side switching elements of the half-bridges connected to the phase conductors of the first converter circuit (150); Opening (217_5) of the electromechanical switching elements of the phase conductors (S1 , S2, S3) and the center tap (S6); Closing (218_1 ) of the low-side switching elements of the half-bridges of the first converter circuit (150) connected to the phase conductors and of the switching element blocking in two current directions connected to the midpoint of the half-bridge of the neutral conductor; Determine (220) the charging currents using the current sensors (Ax) of the phase conductors; Determine (221) the voltages using the voltage sensors (Ux); Detect (227) a faulty electromechanical switching element (Sx) when a measured charging current exceeds a predefinable current threshold, when a measured voltage exceeds a predefinable voltage threshold, or when the gradient of the difference between the intermediate circuit voltage and the capacitor voltage exceeds a predefinable gradient threshold.

9. Method according to claim 3 or 4, wherein the detection (230) of the faulty electromechanical switching element comprises the steps: Precharging (216) of the DC intermediate circuit (170) by means of the second converter circuit (160), especially in reverse operation; Closing (217_6) of the electromechanical switching elements of the phase conductors (S1 , R. 416584 - 24 - S2, S3); Closing (218_1 ) of the low-side switching elements of the half-bridges of the first converter circuit (150) connected to the phase conductors and of the switching element blocking in two current directions connected to the midpoint of the half-bridge of the neutral conductor; Determine (220) the charging currents using the current sensors (Ax) of the phase conductors; Determine (221) the voltages using the voltage sensors (Ux); Detect (227) a faulty electromechanical switching element (Sx) when a measured charging current exceeds a predefinable current threshold, when a measured voltage exceeds a predefinable voltage threshold, or when the gradient of the difference between the intermediate circuit voltage and the capacitor voltage exceeds a predefinable gradient threshold.

10. Method according to claim 3 or 4, wherein the detection (230) of the faulty electromechanical switching element comprises the steps: Precharging (216) of the DC intermediate circuit (170) by means of the second converter circuit (160), especially in reverse operation; Closing (217_7) of the electromechanical switching elements of the phase conductors (S1 , S2, S3) and the neutral conductor (S5); Closing (218_1 ) of the low-side switching elements of the half-bridges of the first converter circuit (150) connected to the phase conductors and of the switching elements blocking in two current directions connected to the midpoint of the half-bridge of the neutral conductor; Determine (220) the charging currents using the current sensors (Ax) of the phase conductors; Determine (221) the voltages using the voltage sensors (Ux); Detection of a faulty electromechanical switching element (Sx) when a measured charging current falls below a predefinable current threshold, when the sum of a measured voltage and the negative capacitor voltage exceeds a predefinable voltage threshold, or when the gradient of the capacitor voltage falls below a predefinable gradient threshold. R. 416584 - 25 - 11. Control unit (105) for operating a charger (100), wherein the control unit (105) is configured to control the charger (100) in such a way that a method (200) according to one of the preceding claims is carried out.

12. Powertrain (300) for a vehicle (400), wherein the powertrain (300) comprises at least one control unit (105) according to claim 11 and a charger (100) and / or an energy storage device (130).

13. Vehicle (400) with a drive train (300) according to claim 12.

14. Computer program comprising commands that cause the control unit (105) according to claim 11 to perform the method steps according to any one of claims 1 to 10.

15. Machine-readable medium comprising commands which, when executed by a control unit (105) according to claim 11, cause it to execute the process steps of the method (200) according to any one of claims 1 to 10.

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