Charging device, and method for operating the charging device

Abstract

The invention relates to a charging device for a vehicle, the input side of the charging device (500) comprising an input terminal unit (100) for connecting a multiphase alternating voltage and a PFC stage (200) for providing a direct voltage at an intermediate terminal (300), a second connection line (120) being divided into a first part of the second connection line (120_1) and a second part of the second connection line (120_2), and a second switching element (S2) being provided which is located between the first part of the second connection line (120_1) and the second part of the second connection line (120_2) and being designed to conduct a charging current from the second input terminal (L2) via the first part and the second part of the second connection line (120_1, 120_2) to the second choke (204), or to conduct a charging current from the first connection line (110) via the second part of the second connection line (120_2) to the second choke (204).

Description

[0001] Description

[0002] title

[0003] Charger and method for operating the charger

[0004] The invention relates to a charger and a method for operating the charger. Furthermore, the invention relates to a powertrain with a charger, a vehicle with a powertrain, a computer program, and a computer-readable storage medium.

[0005] State of the art

[0006] Chargers, for example in electric vehicles or hybrid vehicles, are used to recharge batteries, preferably accumulators or traction batteries, from an electrical energy source, preferably an external AC source or the public AC grid. To do this, the charger converts a sinusoidal alternating current from the external energy source into a direct current. With single-phase alternating current, the power pulses at twice the frequency of the alternating current.

[0007] Chargers preferably have two-stage power electronics. A first stage, the so-called power factor correction stage, or PFC stage, converts the sinusoidal input voltage from the AC mains into a DC voltage. A second stage consists of a DC-DC converter or DC / DC converter, which ensures galvanic isolation via a transformer and adjusts the voltage levels. The output voltage and / or output current for charging the battery is preferably adjusted using an electrical circuit and a control system. An intermediate capacitor is arranged between the two stages, which buffers the power pulsation at twice the frequency of the AC current of the energy source. This intermediate circuit is typically implemented using at least one electrolytic capacitor.These topologies enable the maintenance of a nearly sinusoidal input current on the grid side to meet grid-side standards, galvanic isolation between the grid and the vehicle to meet safety requirements, and the provision of a constant DC output current on the battery side to minimize the load on the battery during charging.

[0008] In an electric vehicle, the battery is also connected to an inverter to supply the electric drive motor with power. A DC-DC converter is connected in parallel to the inverter to supply a low-voltage network or the vehicle's on-board electrical system to supply the control units with power. At the start of the charging process, the charger is connected to the sinusoidal input voltage from the AC voltage network, or the AC low-voltage network, via a PFC stage. The PFC stage is connected or interconnected on the output side to the intermediate capacitor, which is part of a voltage intermediate circuit. The voltage intermediate circuit is discharged when connected to the AC low-voltage network. Due to its low impedance, a high inrush current is generated when the AC low-voltage network is switched on, which charges the voltage intermediate circuit.To prevent grid-side disturbances or the destruction of power electronics components, such as fuse blowouts due to overcurrent, this inrush current must be limited. A common implementation for inrush current limitation is to use pre-charging resistors in the connecting lines between the AC mains and the PFC stage, which are bridged by relays during normal operation. A corresponding inrush current must be limited in each connecting line of the PFC stage. This requires a large number of pre-charging resistors and relays. Therefore, there is a need for a simple and compact solution that enables charging of the intermediate capacitor with fewer components.

[0009] Disclosure of the invention

[0010] A charger for a vehicle is provided, the charger comprising on the input side a multi-phase, n-phase, where n is an integer greater than 1, preferably three-phase, input connection unit for connecting an n-phase AC voltage and a PFC stage for providing a DC voltage at a two-pole intermediate connection. The intermediate connection comprises a positive intermediate connection and a negative intermediate connection. The PFC stage comprises an n-th half-bridge for each of the n-phases. Each half-bridge comprises a series circuit with a high-side switch and a low-side switch. A center tap between the high-side switch and the low-side switch of a half-bridge can be connected via a respective choke to one of the n-input connections of the n-phase input connection unit via a respective n-th connecting line.Thus, for example, the center tap of the first half-bridge can be connected to the first input terminal via the first choke and the first connection line. Thus, for example, the center tap of the second half-bridge can be connected to the second input terminal via the second choke and the second connection line, and so on. The n-type half-bridges are connected in parallel and their ends are connected to the two-pole intermediate connection. The high-side switches are connected to a positive intermediate connection and the low-side switches are connected to a negative intermediate connection of the two-pole intermediate connection. An intermediate capacitor is connected between the positive intermediate connection and the negative intermediate connection. This intermediate capacitor is part of the voltage intermediate circuit. The second connection line is divided into a first part of the second connection line and a second part of the second connection line.A second switching element is provided, which is arranged between the first part of the second connecting line and the second part of the second connecting line, and is configured to conduct a charging current from the second input terminal via the first part and the second part of the second connecting line to the second choke or to conduct a charging current from the first connecting line via the second part of the second connecting line to the second choke. A second switching element, preferably a second changeover contact, is arranged between a first part of the second connecting line and a second part of the second connecting line.Depending on the switching position of the second switching element, a charging current is thus conducted from the second input terminal via the first part and the second part of the second connecting line to the second choke, or a charging current is conducted from the first connecting line via the second part of the second connecting line to the second choke.

[0011] Advantageously, a circuit is provided for a charger with a multi-phase AC voltage input, in which the possibility exists that an inrush current for charging the intermediate capacitor does not flow through all phases of the AC voltage input. Advantageously, the first part of the second connecting line can be decoupled from the PFC stage and thus from the intermediate capacitor by means of the second switching element. Preferably, the first part of the second connecting line is therefore only connected to the PFC stage after the intermediate capacitor has been charged. Preferably, an inrush current is thus prevented when the first part of the second connecting line is connected. Advantageously, a precharging resistor, preferably with a bridging switching element, between the second input connection and the first part of the second connecting line is omitted.Preferably, due to the design of the second switching element as a second changeover contact, a short circuit between the first connecting line and the first part of the second connecting line is prevented. Preferably, a short circuit between the first input terminal and the second input terminal would be possible by means of a faultily controlled simple switching element. This faulty control scenario can be reliably excluded by means of the second changeover contact. Preferably, a switching element corresponding to the second switching element and its arrangement is also installed in further phases, in addition to the first and second phases of a PFC stage, in order to eliminate the need for a precharging resistor in the further phases as well.

[0012] An external energy source is preferably a multi-phase, preferably three-phase AC voltage network, preferably the public low-voltage grid. In a North American region or Japanese region, this is preferably a single-phase AC voltage network with 120 or 240 volts. In a Chinese or European region, this is preferably a three-phase AC voltage network with approximately 230 volts. For charging the charger, the charger is preferably connected to a corresponding AC voltage network via the n-phase input connection unit or connected to the corresponding AC voltage. The n-phase input connection unit preferably comprises a neutral conductor connection for connecting a neutral conductor of the AC voltage network to be connected. A battery to be charged is preferably an accumulator or a traction battery, by means of which energy an electric drive train of a vehicle is operated.A rectification circuit is preferably a rectifier for converting alternating current into direct current. A high-side switch or a low-side switch of a semiconductor bridge is preferably a power semiconductor switch comprising an intrinsic diode, preferably an IGBT or MOSFET, preferably based on Si, SiC, or GaN technology. The phrase "connecting, for example, a center tap to a connecting line" preferably means connecting, contacting, or connecting the components by means of an electrically conductive line or a galvanic connection. The phrase "blocking, preventing, decoupling, or preventing a current flow" means breaking an electrically conductive line or connection.Preferably, the term "switched" is used synonymously with "electrically connected," where "switchably connected" means that an electrical connection can be established or broken, preferably by means of a switch or switching element. Preferably, the term "arranged" is used to define the position of an electrical component, preferably a switch or switching element, within the circuit topology, which includes an electrical connection with the adjacent electrical components.

[0013] In one embodiment, to charge the intermediate capacitor before the start of a charging process, the second switching element is controlled such that a charging current is conducted from the first connecting line via the second part of the second connecting line to the second choke. Therefore, a current flow between the first part of the second connecting line and the second part of the second connecting line is preferably prevented.

[0014] Advantageously, a control of the second switching element is provided that prevents a current flow via a first part of the second connecting line to the second part of the connecting line when charging the intermediate capacitor. This prevents a high inrush current from flowing through the second phase of the input connection unit for connecting the multi-phase AC voltage.

[0015] In one embodiment, the intermediate capacitor is charged until the voltage at the intermediate capacitor equals or exceeds a predeterminable voltage value.

[0016] The second switching element for charging the intermediate capacitor is controlled until the voltage at the intermediate capacitor equals or exceeds a predeterminable voltage value. For this purpose, the voltage at the intermediate capacitor is determined using a detection unit or measuring device and compared with the predeterminable voltage value. This predeterminable voltage value is specified as a function of the voltage applied to the second input terminal or corresponds to it. To determine the predeterminable value, the voltage at the second input terminal is preferably determined using a suitable detection unit or measuring device and is preferably specified as a voltage value depending on the magnitude of the maximum amplitude.Alternatively, the voltage value is preferably specified depending on the connected AC voltage or the region in which the charger is operated, or preferably read out and specified from a characteristic map.

[0017] Alternatively, in another embodiment, the intermediate capacitor is charged until the alternating current through the first and / or second connecting line or through the first connecting line and / or at least the second part of the second connecting line falls below a predeterminable alternating current value. The predeterminable alternating current value is preferably approximately 100 mA. The predeterminable alternating current value is preferably set so low that no overcurrent occurs upon subsequent control of the second switching element in such a way that a charging current is conducted from the second input connection via the second connecting line, via the first part of the second connecting line and via the second part of the second connecting line to the second choke. For this purpose, the alternating current is preferably determined by means of an alternating current measuring unit during the charging of the intermediate capacitor.For this purpose, the alternating current measuring unit is preferably arranged between the first input terminal and the intermediate terminal and / or between the second input terminal and the intermediate terminal.

[0018] Advantageously, a control for the charger is provided which prevents a high inrush current through the second phase of the input connection unit for connecting the multi-phase alternating voltage.

[0019] In another embodiment, in order to provide electrical energy at the intermediate terminal for a charging process, an alternating voltage provided at the input terminal unit is provided via the PFC stage at least partially as a direct voltage at the positive intermediate terminal and at the negative intermediate terminal, wherein the second switching element is controlled such that a charging current is conducted via at least the first connecting line and the second connecting line, or via at least the first connecting line and at least the second part of the second connecting line, and via the PFC stage to the intermediate terminal.

[0020] During a charging process, the charger converts electrical energy provided at the input connection unit, the provided alternating voltage or the provided alternating current, into a charging voltage for charging a battery, preferably for charging a vehicle battery. For this purpose, the charger has a two-stage design. The first stage, the PFC stage, converts the sinusoidal input voltage from the alternating voltage network into a direct voltage at the voltage intermediate circuit. The second stage, a downstream DC-DC converter, which preferably ensures galvanic isolation via a transformer, adjusts the voltage levels, and on the output side, the charging voltage and charging current for charging the battery are provided by means of a circuit and a control system.Preferably, in the case of a single-phase AC voltage, the second switching element is controlled in such a way that a charging current is conducted via at least the first connecting line and at least the second part of the second connecting line and via the PFC stage to the intermediate connection. Preferably, the charging current is distributed across two phases within the PFC stage, thus reducing the load on the electronic components. Advantageously, the charger can be operated with a higher charging current in single-phase operation than in multi-phase operation. Preferably, in the case of a two- or multi-phase AC voltage, the second switching element is controlled in such a way that a charging current is conducted via at least the first connecting line and also the second connecting line and via the PFC stage to the intermediate connection.Preferably, the charging current from the AC mains is routed directly via the PFC stage to the intermediate connection for each phase.

[0021] Advantageously, a topology is provided which enables a DC voltage to be provided at the intermediate terminal for a charging process, the energy for this being provided by an external energy source which provides a multi-phase AC voltage at the input terminal unit.

[0022] In another embodiment, a first switching element is provided and configured to enable or interrupt a current flow between the first input terminal and the first connection line through the first switching element.

[0023] A first switching element is arranged between the first connecting line and the first input terminal. A first switching element is provided and configured to enable or interrupt a current flow between the first input terminal and the first connecting line or the first choke of the PFC stage. Depending on the switching position, a current flow or a charging current from the first input terminal through the first switching element toward the first choke of the PFC stage is thus enabled or prevented.

[0024] Advantageously, the first switching element provides the possibility of interrupting or switching on a charging current via the first connection line through the first switching element. Preferably, a precharging resistor, preferably a PTC resistor, is connected in parallel with the first switching element and is used to limit an inrush current. When charging the intermediate capacitor, the inrush current preferably flows from the first input terminal via the precharging resistor through the PFC stage into the intermediate capacitor. The precharging resistor reduces the inrush current and thus prevents an overcurrent. Preferably, to avoid losses in the series resistor, the series resistor is bypassed by closing the first switching element when the intermediate capacitor is substantially charged.

[0025] In another embodiment, the intermediate capacitor is designed as a series circuit comprising a first capacitor and a second capacitor.

[0026] The intermediate capacitor is preferably designed as a series connection of a first and a second capacitor. The capacitance of the first capacitor and the second capacitor is preferably the same. A neutral conductor, preferably switchable, is preferably connected to a center tap between the first and the second capacitor for connection to a corresponding contact of the input connection unit. A neutral conductor is preferably provided for operation of the charger with asymmetrical loading. An asymmetrical load preferably occurs when operating with a 2-phase mains or with asymmetrical loading when operating with a 3-phase mains, i.e. two-phase or three-phase alternating voltage. In these cases, a compensating current flows back into the alternating voltage network connected on the input side via the neutral conductor.

[0027] Advantageously, a suitable circuit topology for connecting a neutral conductor is provided.

[0028] In another embodiment, a third switching element is provided and configured to enable or interrupt a charging current between the third input terminal and the third connecting line or the third choke of the P FC stage.

[0029] A third switching element is arranged between the third connecting line and the third input connection. Depending on the switching position, a current flow or a charging current from the third input connection in the direction of the third choke of the P FC stage is thus enabled or prevented. Advantageously, a possibility is created to interrupt or switch on a charging current via the third connecting line, preferably when a three-phase charging current is present. Preferably, a pre-charging resistor, preferably a PTC thermistor or PTC resistor, is connected in parallel with the third switching element and is used to limit an inrush current. Preferably, the inrush current flows from the third input connection via the P FC stage into the first and / or the second capacitor. Preferably, to avoid losses in the pre-charging resistor, this is bridged by closing the third switching element when the first and / or second capacitor is substantially charged.

[0030] Furthermore, the invention relates to a drive train of a vehicle with a charger as described above, wherein the drive train comprises, in particular, a traction battery, an inverter, and / or an electric machine. Advantageously, a drive train of an electric vehicle with a charger with a simplified circuit topology is provided.

[0031] Furthermore, the invention relates to a vehicle with a drive train as described above.

[0032] Advantageously, a vehicle is provided with a charger having a simplified circuit topology.

[0033] Furthermore, the invention relates to a method for operating a charger as presented above, comprising the step of: controlling the second switching element, and preferably the first switching element, and the high-side and low-side switches of the half-bridges to provide electrical energy at the two-pole intermediate connection.

[0034] By controlling the second switching element, and preferably the first switching element, and the switches of the half-bridges, the alternating voltage applied to the input terminal is first used to charge the intermediate capacitor and then permanently converted into a direct voltage to supply the connected DC-DC converter of the charger to generate the charging voltage for the battery to be charged. Advantageously, a method is provided that enables the provision of a direct voltage at the voltage intermediate circuit. Furthermore, the invention relates to a computer program comprising instructions that, when the program is executed by a computer, cause the computer to execute the described method.

[0035] Furthermore, the invention relates to a computer-readable storage medium comprising instructions which, when executed by a computer, cause the computer to carry out the described method.

[0036] It is understood that the features, characteristics and advantages of the charger apply accordingly to the method or the powertrain and the vehicle and vice versa.

[0037] Further features and advantages of embodiments of the invention will become apparent from the following description with reference to the accompanying drawings.

[0038] Short description of the drawing

[0039] In the following, the invention will be explained in more detail with reference to some figures, which show:

[0040] Figure 1 is a schematic representation of an embodiment of a circuit topology for a charger known from the prior art

[0041] Figure 2 is a schematic representation of an embodiment of a circuit topology for a charger,

[0042] Figure 3 shows a schematic representation of a vehicle with a drive train with a charger,

[0043] Figure 4 is a schematic flow diagram for a method for operating a charger

[0044] Embodiments of the invention

[0045] Figure 1 shows a charger 500, preferably for a vehicle. The charger 500 comprises, on the input side, an input connection unit 100 for connecting a three-phase alternating voltage (illustrated by way of example), and a PFC stage 200 for providing a direct voltage at an intermediate terminal 300. The PFC stage 200 of the charger 500 comprises a first 210, a second 220, and a third 230 half-bridge. The first, second and third half-bridges 210, 220, 230 each comprise a series circuit with a high-side switch 211, 213, 215 and a low-side switch 212, 214, 216. A center tap between the high-side switch and the low-side switch of a half-bridge can be connected via a first, second and third choke 202, 204, 206 to a first, second and third input terminal LI, L2, L3 of the input connection unit 100 via a first, second and third connection line 110, 120, 130.Thus, the center tap of the first half-bridge 210 is connectable to the first input terminal L1 via the first choke 202 and the first connecting line 110. Thus, the center tap of the second half-bridge 220 is connectable to the second input terminal L2 via the second choke 204 and the second connecting line 120. Thus, the center tap of the third half-bridge 230 is connectable to the third input terminal L3 via the third choke 206 and the third connecting line 130. The half-bridges 210, 220, 230 are connected in parallel. Their ends are connected to the two-pole intermediate terminal 300. The high-side switches are connected to a positive intermediate terminal 310 and the low-side switches to a negative intermediate terminal 320. A DC-DC converter 450 is preferably connected to the intermediate terminal 300.The DC voltage at the intermediate connection 300, which is present on the input side of the DC-DC converter 450, is preferably converted into a charging voltage for charging a battery 470, preferably a traction battery or high-voltage battery, that can be connected to the output side of the DC-DC converter 450. Preferably, a further DC-DC converter 460, preferably a step-down converter, is connected in parallel to the battery 470 to convert the charging voltage into a low-voltage voltage for charging a low-voltage battery 462 and for supplying a vehicle's electrical system to power the vehicle's control units. The low-voltage battery 462, as well as preferably further low-voltage consumers 480, are connected to the vehicle's electrical system. The further DC-DC converter 460 is preferably a bidirectional DC-DC converter.Preferably, the additional DC-DC converter 460 can be used to precharge the high-voltage intermediate circuit before the battery 470 is connected to the charger 500. The high-voltage intermediate circuit is connected to the output side of the DC-DC converter 450.

[0046] Starting with the charger 500 shown in Figure 1, the charger 500 according to the invention shown in Figure 2 comprises an n-phase input connection unit 100 for connecting a multi-phase alternating voltage with n phases, where n is greater than 1. A three-phase input connection unit for connecting a three-phase alternating voltage is shown as an example. The second connecting line 120 is divided into a first part of the second connecting line 120_1 and a second part of the second connecting line 120_2. For this purpose, a second switching element S2 is provided, which is arranged between the first part of the second connecting line 120_1 and the second part of the second connecting line 120_2.The second switching element S2 is configured to conduct a charging current from the second input terminal L2 via the first part and the second part of the second connecting line 120_1, 120_2 to the second inductor 204 or to conduct a charging current from the first connecting line 110 via the second part of the second connecting line 120_2 to the second inductor 204. To implement this function, the second switching element S2 is preferably designed as a changeover contact. A first switching element S1 is preferably provided and configured to enable or interrupt a current flow between the first input terminal L1 and the first connecting line 110. A third switching element S3 is preferably provided and configured to enable or interrupt a charging current between the third input terminal L3 and the third connecting line 130.Preferably, precharging resistors, preferably switchable resistors, PTC thermistors or PTC resistors, are connected in parallel to the first S1 and the third S3 switching element so that an inrush current is limited when an AC voltage is connected to the input connection unit 100 before the first and third switching elements S1, S3 are closed. An intermediate capacitor CZ is connected in parallel to the half-bridges 210, 220, 230. The intermediate capacitor CZ is preferably replaced by a series circuit comprising a first C1 and a second C2 capacitor (not shown). Preferably, a current sensor (not shown) is arranged in series with the first, second and third chokes 202, 204, 206 in order to determine the current through the respective choke 202, 204, 206. Depending on the currents determined, the high-side switches and the low-side switches as well as the switching elements are preferably controlled to implement the desired operating modes.Preferably, a voltage sensor (V) is arranged between the positive and negative intermediate terminals 310, 320 for determining or measuring the voltage at the intermediate capacitor. Depending on the determined voltage, the high-side switches and the low-side switches as well as the switching elements are preferably controlled to implement the desired operating modes. Preferably, the negative intermediate terminal 320 is connected to ground GND. Preferably, GND is an internal voltage potential. Preferably, the voltage at the intermediate capacitor between the positive intermediate terminal 310 and the negative intermediate terminal 320 is measured or determined. Preferably, the voltage at the second input terminal against a neutral conductor terminal (not shown) is measured and determined. Preferably, the switching elements are provided as semiconductor switch components (IGBTs or MOSFETS, based on Si, SiC or GaN) or as contactors or relays.

[0047] Figure 3 shows a schematically illustrated vehicle 700 with a drive train 600 and a charger 500. The vehicle 700 is illustrated here only as an example with four wheels, although the invention can be used equally in any vehicle with any number of wheels on land, on water, and in the air. The drive train 600 illustrated as an example comprises at least one charger 500. Furthermore, the drive train preferably comprises a battery 470, an inverter 472, and / or an electric machine 474.

[0048] Figure 4 shows a schematic flowchart for a method 800 for operating a charger 500. The method 800 begins with step 805. In step 810, the second switching element S2, preferably the first switching element S1, as well as the high-side and low-side switches of the half-bridges 210, 220, 230 are controlled to provide electrical energy to the intermediate capacitor CZ. The method ends with step 815.

Claims

Charger for a vehicle, wherein the charger (500) comprises on the input side an input connection unit (100) for connecting a multi-phase alternating voltage with n-phases, where n is greater than 1, and a P FC stage (200) for providing a direct voltage at an intermediate connection (300), wherein the PFC stage (200) comprises a half-bridge (210, 220, 230) for each phase of the n-phases, wherein a half-bridge (210, 220, 230) each comprises a series circuit with a high-side switch (211, 213, 215) and a low-side switch (212, 214, 216), wherein a center tap between the high-side switch and the low-side switch of the half-bridge is connected via a respective choke (202, 204, 206) to each of the n-input terminals (LI, L2, L3) of the input connection unit (100) can be connected via an n-th connection line (110, 120, 130), wherein the n-half bridges (210, 220,230) are connected in parallel and whose ends are connected to the two-pole intermediate terminal (300), wherein the high-side switches are connected to a positive intermediate terminal (310) and the low-side switches are connected to a negative intermediate terminal (320), wherein an intermediate capacitor (CZ) is connected between the positive intermediate terminal (310) and the negative intermediate terminal (320), characterized in that a second connecting line (120) is divided into a first part of the second connecting line (120_l) and into a second part of the second connecting line (120_2), wherein a second switching element (S2) is provided, which is arranged between the first part of the second connecting line (120_l) and the second part of the second connecting line (120_2), and is designed to supply a charging current from the second input terminal (L2) via the first part and the second part of the second connecting line (120_l,120_2) to the second choke (204) or to conduct a charging current from the first connecting line (110) via the second part of the second connecting line (120_2) to the second choke (204). The charger according to claim 1, wherein, to charge the intermediate capacitor (CZ) before the start of a charging process, the second switching element (S2) is controlled such that a charging current is conducted from the first connecting line (110) via the second part of the second connecting line (120_2) to the second choke (204). The charger according to claim 2, wherein the intermediate capacitor (CZ) is charged until the voltage across the intermediate capacitor (CZ) exceeds a predeterminable voltage value.Charger according to one of the preceding claims, wherein, in order to provide electrical energy at the intermediate terminal (300) for a charging process, an alternating voltage provided at the input terminal unit (100) is provided via the PFC stage (200) at least partially as a direct voltage at the positive intermediate terminal (310) and at the negative intermediate terminal (320), wherein the second switching element (S2) is controlled such that a charging current is conducted via at least the first connecting line (110) and the second connecting line (120), or via at least the first connecting line (110) and at least the second part of the second connecting line (120_2), and via the PFC stage (200) to the intermediate terminal (300).Charger according to one of the preceding claims, wherein a first switching element (S1) is provided and configured to enable or interrupt a current flow between the first input terminal (L1) and the first connecting line (110) through the first switching element (S1). Charger according to one of the preceding claims, wherein the intermediate capacitor (CZ) is designed as a series circuit comprising a first capacitor (C1) and a second capacitor (C2). Drive train (600) of a vehicle (700) with a charger (500) according to one of the preceding claims, wherein the drive train (600) in particular. a traction battery (470), an inverter (472) and / or an electric machine (474). Vehicle (700) with a drive train (600) according to claim 7. Method (800) for operating a charging device according to one of claims 1 to 6, comprising the step: Controlling (810) the second switching element (S2) as well as the high-side and low-side switches of the half-bridges (210, 220, 230) to provide electrical energy to the intermediate capacitor (CZ). A computer program comprising instructions which, when executed by a computer, cause the computer to carry out the method (800) according to claim 9. A computer-readable storage medium comprising instructions which, when executed by a computer, cause the computer to carry out the method (800) according to claim 9.

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