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

Abstract

Method and device for operating a charging device having electromechanical switching elements (S1, S2), wherein a faulty one of the electromechanical switching elements (Sx) in the charging device (100) is detected as a function of a frequency of an alternating voltage determined by means of a sensor device, and a fault signal (F) is output upon detection of a faulty electromechanical switching element (Sx).

Description

[0001] R. 415237

[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 from the energy storage device via an external or internal socket connection in the vehicle, or via a socket for a standard electrical appliance. 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, among other things, 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. 415237 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 method for operating a vehicle charger is provided. The charger comprises, on its input side, a multi-phase input connection unit with at least one first and one second phase conductor connection and a neutral conductor connection for connecting a power source. An input connection unit is preferably a socket or configured to receive 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 terminal for connecting an energy storage device to be charged. Preferably, the output terminal 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 and the output terminal, the charger includes a charging circuit. On the input side, towards the input terminal, the charging circuit includes 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 input AC voltage. On the output side, i.e., towards the output terminal, the charging circuit includes a second converter circuit.Preferably, this second converter circuit is a controllable DC-DC converter, which is configured to generate a DC voltage on the output side from a DC voltage applied on the input side. R. 415237.

[0013] - 3 - to provide. The first and second converter circuits are connected to each other via a DC link. A DC link voltage is applied to the DC link, preferably between an upper and a lower potential of the DC link. More preferably, the DC link between the upper and lower potentials of the DC link comprises at least one capacitor or a series connection of two capacitors, so-called DC link capacitors. The at least two phase conductors of the input connection unit are each connected to the charging circuit of the charger via an electromechanical switching element. Preferably, electromechanical switching elements are designed as contactors or relays.The charger has at least one sensor device between the input terminal unit and the electromechanical switching elements for determining the frequency of an alternating voltage between the two phase conductors. The method comprises the following steps:

[0014] Detecting a faulty electromechanical switching element in the charger based on an alternating voltage frequency determined by the sensor device; outputting an error signal after detecting a faulty electromechanical switching element; preferably terminating the charger's operation and bringing it to a safe state. Preferably, the operation is a vehicle-to-load diagnostic mode, preferably providing an alternating 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 sensor device determines whether an alternating voltage frequency is detected after a change in the switching state of at least one electromechanical switching element.Preferably, depending on the determined frequency, 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, a frequency of an alternating voltage is determined by means of the sensor device. Preferably, the alternating voltage, preferably its waveform, is determined by the sensor device, and a frequency of the determined alternating voltage is calculated by means of a connected evaluation device or a controller, preferably the control unit. R. 415237.

[0015] - 4 - The voltage is determined. Preferably, depending on the determined frequency, it is detected 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 when a faulty electromechanical switching element is detected. Preferably, the output of an error signal includes corresponding information transmission to a logic unit or a controller inside or outside the control unit so that an appropriate reaction to the detected error occurs and / or a notification is sent to the user. Preferably, this serves to inform a user as well as to control fault operation of the charger and / or the vehicle, preferably to control the termination of operation of the charger or the charging process and / or to bring the charger into a safe state.Preferably, transitioning to a safe state involves opening the switchable connections of the charger to the power sources or energy storage devices and discharging any existing DC link capacitors to minimize the charger's touch voltage. This method is preferably performed during the charger's shutdown, preferably while the vehicle is stationary, preferably after the charger has been used to charge the energy storage device from an AC power source and the charger has been disconnected from the AC power source, or after an external vehicle-to-load operation. Therefore, the charger's power supplies are preferably switched off and the electromechanical switching elements of the phase conductors are open. Furthermore, this method is preferably performed while the vehicle is in operation, preferably before or after the charger has been used for an internal vehicle-to-load function.

[0016] 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.

[0017] In one embodiment, the charger's sensor device includes a frequency sensor; the detection of the faulty electromechanical switching element depends on the frequency of an alternating voltage between the first and second phase conductors, as determined by the frequency sensor. R. 415237

[0018] - 5 -

[0019] Advantageously, an improved and extended method is provided for the safe operation of a charger with electromechanical switching elements. For this purpose, a special sensor device is used in the charger to detect faulty electromechanical switching elements.

[0020] In one embodiment, the first converter circuit is preferably configured as a bidirectionally operable PFC stage. Preferably, the first converter circuit has an input inductor for each phase conductor. Each input inductor is preferably connected to a half-bridge center tap of one half-bridge of the first converter circuit. For this purpose, each input inductor is preferably connected on one side to a terminal of a current sensor for the phase conductors and on the other side to a half-bridge center tap of one of the half-bridges for each phase conductor of the first converter circuit. Preferably, 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.

[0021] 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. For this method, a special sensor device is used in the charger to detect faulty electromechanical switching elements.

[0022] In one embodiment, the detection of the faulty electromechanical switching element comprises the following steps: receiving an input signal indicating that no power source is connected to the input terminal unit; opening one of the first electromechanical switching elements and closing a second electromechanical switching element; operating the first converter circuit in reverse to generate an alternating voltage; determining a frequency using the sensor device; and detecting a faulty electromechanical switching element when a frequency is determined. R. 415237

[0023] - 6 -

[0024] Preferably, the electromechanical switching element is recognized as permanently closed, which was activated during the opening process.

[0025] Preferably, an input signal indicating that no power source is connected to the input terminal unit is received, rather than a signal from the power source itself, such as an external charger or a charging station. Alternatively, a signal from the vehicle indicating that a driving mode is active can be used to conclude that no power source is connected. Similarly, with electromechanical switching elements open, the charger's voltage sensors can determine the voltages between the phase conductors and the neutral conductor at the input terminal unit. As long as the measured voltages are below a predefined threshold, it is concluded that no power source, preferably an AC power source, is connected to the input terminal unit.This AC power source is preferably an external charger configured for charging, and preferably for transferring electrical energy to, an energy storage device connectable to the charger. Preferably, an electromechanical switching element is opened by means of a control unit and a signal line. Preferably, an electromechanical switching element is closed by means of a control unit and a signal line. Preferably, the DC link, and preferably the at least one capacitor of the DC link, is first charged or pre-charged with energy from the connectable energy storage device by means of operation, preferably by reverse operation, of 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 for carrying out the subsequent process or diagnostic steps. Preferably, the DC link, or more preferably the at least one capacitor of the DC link, is then discharged towards the input terminal unit by operating, preferably by reverse operation, the first converter circuit. The first converter circuit is driven such that an AC voltage with a predefinable frequency is generated between the first and second phase conductors. If both R. 415237.

[0026] - 7 - When the electromechanical switching elements are closed, the sensor device determines the frequency of the generated alternating voltage. However, according to the method, preferably one electromechanical switching element is closed and one is open alternately. Therefore, the alternating voltage is not present at the sensor device, and the sensor device cannot determine the specified frequency. A faulty electromechanical switching element, preferably a permanently closed electromechanical switching element, is therefore detected when the described behavior does not occur and a frequency is thus determined by the sensor device. These general explanations of the method also apply to the following embodiments or configurations.

[0027] Advantageously, a more detailed procedure is provided for the safe operation of a charger with electromechanical switching elements. For this purpose, a special sensor device is used in the charger to detect faulty electromechanical switching elements.

[0028] In one embodiment, the detection of the faulty electromechanical switching element comprises the following steps: pre-charging the DC intermediate circuit using the second converter circuit, particularly in reverse operation;

[0029] Preferably, the DC link, and more preferably the at least one capacitor of the DC link, is charged or pre-charged by operating, preferably by reverse operation, the second converter circuit with energy from the connectable energy storage device. Preferably, the DC link is charged to a predefinable voltage. The voltage level is selected such that sufficient energy is available to carry out the subsequent process or diagnostic steps.

[0030] Advantageously, a more detailed procedure for the safe operation of a charger with electromechanical switching elements is provided. For this purpose, a special sensor device is used in the charger to detect faulty electromechanical switching elements. R. 415237

[0031] - 8 -

[0032] 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.

[0033] 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.

[0034] 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.

[0035] Furthermore, the invention relates to a computer program comprising commands that cause the control unit to execute the described process steps.

[0036] 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.

[0037] It is understood that the features, properties, and advantages of the method according to the invention apply accordingly to the control unit, the powertrain, and the vehicle, and vice versa. R. 415237

[0038] - 9 -

[0039] Further features and advantages of embodiments of the invention will become apparent from the following description with reference to the accompanying drawings.

[0040] Brief description of the drawing

[0041] The invention will be explained in more detail below using some figures, including:

[0042] Figure 1 shows a schematic representation of a charger,

[0043] Figure 2 shows a schematic representation of a vehicle with a drivetrain and a charger.

[0044] Figure 3 shows a schematic representation of a method for operating a charger.

[0045] Embodiments of the invention

[0046] Figure 1 shows a charger 100. The charger 100 comprises, on its input side, a multi-phase input terminal unit 110 with at least one first and one second phase conductor terminal Lx and a neutral conductor terminal N for connecting a power source (not shown). On its output side, the charger comprises a two-pole output terminal unit 120 for connecting an energy storage device 130 to be charged. The energy storage device is preferably a high-voltage battery or a traction battery for powering the vehicle, for 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, on its input side, a first converter circuit 150 and, on its output side, a second converter circuit 160. Preferably, the first converter circuit 150 is a PFC stage (power factor correction circuit).Preferably, the PFC stage is designed to be connected to AC voltage on the input side and to R. 415237 on the output side.

[0047] - 10 -

[0048] to be connected to a DC voltage. Preferably, the PFC stage 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 applied to the DC link 170. Preferably, the DC link 170 includes a capacitor or a series connection of two capacitors C1 and C2 between the upper and lower potentials. Preferably, the first and second capacitors have the same capacitance. The first converter circuit 150 preferably includes an inductor or choke on each phase conductor at the input, each of which is connected to a half-bridge center tap of one 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 second converter circuit 160 preferably comprises a bidirectionally operable DC-DC converter circuit, preferably with galvanic isolation. For example, 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) or LLC 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 energy storage device 130, and in reverse mode energy is transferred from the output-side energy storage device 130 towards the input-side DC link 170. Preferably, the DC link is pre-charged in reverse mode. Preferably, the output-side energy storage device is charged in forward mode, preferably by discharging the DC link 170, preferably while the electromechanical switching elements of the phase conductors are open. The phase conductors Lx of the input connection unit 110 are each connected via an electromechanical switching element S1, S2, and preferably via a subsequent current sensor A1, A2, with R. 415237.

[0049] - 11 - of the charging circuit 140. Furthermore, the charger 100 comprises an ACDC sensor device between the input connection unit 110 and the electromechanical switching elements for determining the frequency of an alternating voltage between a first and a second phase conductor. 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, the semiconductor switching elements, the first and second converter circuits, and the evaluation of the signals from the sensor device, at least for carrying out the described methods.

[0050] 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 a charger 100. Preferably, the drive train further comprises an energy storage device 130, an inverter 180, and / or an electric machine 190. In Figure 2, the control unit 105 is preferably shown as part of the charger 100. However, the control unit 105 can also be arranged outside the charger 100. In this case, the control unit 105 would be connected to the charger 100 via appropriate communication means, ensuring information exchange and control. The illustration shows an example of a four-wheeled vehicle, but the invention can be used equally well in any vehicle with any number of wheels on land, water, and in the air.

[0051] 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 an alternating voltage frequency determined by a sensor device. 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 aborted, preferably by opening the electromechanical switching elements and / or the semiconductor switching elements of the charger 100, and / or the charger 100 is brought into a safe state, preferably by discharging the DC link capacitor by forward operation of the second R. 415237

[0052] - 12 -

[0053] Converter circuit 160 or preferably by opening the electromechanical switching elements and / or the semiconductor switching elements of the charger 100. The method ends with step 260. As already described above, the method preferably includes further steps for detecting the faulty electromechanical switching element.

Claims

R. 415237 - 13 - Claims 1. Method 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 a first and a second phase conductor terminal (L1, L2) and a neutral conductor terminal (N) for connecting a power source, on the output side a two-pole output terminal unit (120) for connecting an energy storage device (130) to be charged, and between the input terminal unit (110) and the output terminal unit (120) 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 at least one capacitor between an upper and a lower potential of the DC link (170), wherein phase conductors (L1, L2) of the input terminal unit (110) are each connected to the charging circuit (140) via an electromechanical switching element (S1, S2), wherein the charger (100) comprises a sensor device (ACDC) between the input terminal unit (110) and the electromechanical switching elements (S1, S2), comprising the steps: Detection (230) of a faulty electromechanical switching element (Sx) in the charger (100) depending on a frequency of an alternating voltage determined by means of the sensor device; Output (240) of an error signal (F) after detection of a faulty electromechanical switching element (Sx). R. 415237 - 14 - 2. Method according to claim 1, wherein the sensor device of the charger (100) comprises a frequency sensor; wherein the detection (230) of the faulty electromechanical switching element (Sx) is carried out depending on the frequency of an alternating voltage between the first and the second phase conductor determined by means of the frequency sensor.

3. Method according to claim one of the preceding claims, wherein the first converter circuit (150) is configured as a bidirectionally operable PFC stage.

4. Method according to claim one of the preceding claims, wherein the detection (230) of the faulty electromechanical switching element comprises the steps: Receiving (213) an input signal (SE) indicating that no power source is connected to the input terminal unit (110), Opening (212) one of the first electromechanical switching elements (S1 , S2) and closing one of the second electromechanical switching elements (S1 , S2), operating the first converter circuit in reverse operation to generate an alternating voltage; Determining (220) a frequency using the sensor device; Detect (226) a faulty electromechanical switching element (Sx) when a frequency is determined.

5. The method of claim 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.

6. 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. R. 415237 - 15 - 7. Powertrain (300) for a vehicle (400), wherein the powertrain (300) comprises at least one control unit (105) according to claim 6 and a charger (100) and / or an energy storage device (130).

8. Vehicle (400) with a powertrain (300) according to claim 7.

9. Computer program comprising instructions that cause the control unit according to claim 6 to execute the process steps according to any one of claims 1 to 5.

10. Machine-readable medium comprising instructions that, when executed by a control unit (105), cause it to execute the process steps of the method (200) according to any one of claims 1 to 5.

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