High-voltage charging circuit and in-vehicle electrical network on the vehicle side

Abstract

A high-voltage charging circuit on the vehicle side, which is equipped with an AC voltage connector (WA); at least two electrically isolated DC voltage converters (W1, W2) configured as boost choppers and a rectifier (G), through which the DC voltage converters (W1, W2) are connected to the AC voltage connector (WA); and a changeover switch (US). The charging circuit has first and second DC voltage connectors (A1, A2), which can be selectively connected to the first DC voltage converter (W1) via the changeover switch (US). The charging circuit has a third DC voltage connector (A3), which is permanently connected to the second DC voltage converter, wherein the charging circuit furthermore has a control device (S), which is set up to control the DC voltage converter in a first mode according to a first rated output voltage, the first rated output voltage being at least 750 V and at most 1000 V; and in a second mode according to a second rated output voltage, the second rated output voltage being at most 480 V or at most 450 V. Furthermore, an on-vehicle electrical network having a high-voltage charging circuit on the vehicle side is described.

Description

Technical Field

[0001] The present invention relates to a high-voltage charging circuit on the vehicle side and a vehicle electrical network. Background Art

[0002] Vehicles with electric drive devices, so-called electric vehicles and hybrid vehicles, have a storage battery for feeding the electric drive device of the vehicle. In addition, there are other electrical components that must be supplied with electrical energy, such as electric heating elements or electronics. In addition, in so-called plug-in vehicles, there is the possibility of charging the vehicle from the outside through at least one electrical connector. In order to be able to perform this step as quickly as possible, the method is to use a storage battery with a high rated voltage above 400V (for example, 600V or especially 800V or 1000V).

[0003] Other components are designed for different voltages, for example, for a voltage of 400V, and in addition, there are low-voltage components designed for a rated voltage of, for example, 12V. In order to be able to implement the functions mentioned above, considering the multiple different voltage levels mentioned within the same vehicle electrical network, a large number of DC voltage converters and other components can be used to connect vehicle electrical network sections with different rated voltages. The task of the present invention is to show a possibility by which the functions mentioned in the vehicle electrical network and the different voltage levels of the vehicle electrical network can be implemented with a deliberately lower number of components at low cost. Summary of the Invention

[0004] This task is solved by a high-voltage charging circuit on the vehicle side and a vehicle electrical network according to the present invention.

[0005] It is proposed to construct a high-voltage charging circuit on the vehicle side, which has a rectifier connected to two DC voltage converters. Different components or vehicle electrical network branches with different voltage levels are connected to one of these DC voltage converters of the vehicle electrical network through a changeover switch according to a mode (or the switch state of the changeover switch). Another DC voltage connection is directly connected to the rectifier without passing through the DC voltage converter, so that the possibility of connecting other components (with their own voltage levels) can be realized. Therefore, electrical energy can be supplied to different components through the changeover switch without the need for additional converters. The direct connection to the DC voltage side of the rectifier can also form a DC voltage level, and at the same time, the converter can be unloaded through this voltage supply method, and a voltage different from the converter voltage can also be provided for power supply.

[0006] Therefore, a high-voltage charging circuit on the vehicle side is proposed, and the high-voltage charging circuit has an AC voltage connector, at least two DC voltage converters and a rectifier. The DC voltage converters are electrically isolated and preferably have a transformer, by means of which the electrical isolation is implemented. In particular, the DC voltage converter is configured as a boost chopper. Here, the DC voltage converter has a first side, which is connected to the rectifier (especially to its DC voltage side); and has a second side, which is away from the first side or the rectifier. The DC voltage converter is configured as a boost chopper such that the voltage at the first side of the DC voltage converter can be transferred to the corresponding second side, wherein the voltage at the second side is higher than the voltage at the first side. The DC voltage converter is connected to the AC voltage connector through the rectifier. Here, in particular, the first side of the DC voltage converter is connected to the rectifier.

[0007] In addition, the charging circuit has a changeover switch and first and second DC voltage connectors. They are connected to the changeover switch. The first and second DC voltage connectors are selectively connected to the DC voltage converter through the changeover switch. Therefore, the changeover switch can selectively connect the first DC voltage connector to the first DC voltage converter, or connect the second DC voltage connector to the second DC voltage converter. In various modes, different DC voltage connectors (through the changeover switch) are connected to the first DC voltage converter, wherein the DC voltage converter also outputs different conversion ratios or different voltages to the corresponding DC voltage connectors (the DC voltage connectors are connected to the first DC voltage converter through the changeover switch) in various modes. Therefore, the DC voltage connectors can be selectively connected to the DC voltage converter through the changeover switch, wherein this can be combined with different output voltages of the first DC voltage converter so as to be able to provide different rated voltages at different DC voltage connectors. This is used to supply power to components or in-vehicle electrical network branches with different rated voltages or operating voltages. Thereby, different voltages can be supplied to components or in-vehicle electrical network branches with different rated voltages or operating voltages. In this case, the first DC voltage converter can be used for different operating voltages or to supply power to different components or in-vehicle electrical network branches. Another mode ( "disconnect mode") corresponding to a disconnected switching position can also be envisaged, in which the changeover switch, for example for safety reasons, disconnects both DC voltage connectors from the first DC voltage converter.

[0008] The charging circuit has a third DC voltage connector. This third DC voltage connector is connected to the second DC voltage converter. Here, the connection is preferably permanent in order to supply, for example, a vehicle electrical network branch or component that must be continuously powered, especially for safety reasons. For example, a low-voltage vehicle electrical network branch can be supplied by means of the third DC voltage connector and the second DC voltage converter connected thereto. Here, the low-voltage converter is connected to the third DC voltage connector, and the low-voltage converter is arranged to generate a voltage for the low-voltage vehicle electrical network branch from the voltage generated by the rectifier, for example, a voltage at a level of approximately 12 V (or alternatively 24 V or 48 V).

[0009] Furthermore, the charging circuit preferably has a control device. This control device is arranged to, in a first mode, control the DC voltage converters (i.e., the first and second DC voltage converters) according to a first rated output voltage, the first rated output voltage being at least 750 V (or at least 650 V) and at most 1000 V (or at most 1200 V), for example, approximately 800 V. Furthermore, the control device is arranged to, in a second mode, control the DC voltage converters according to a second rated output voltage, the second rated output voltage being approximately half of this (+-25% or +10%), for example, at most 480 V or at most 450 V. The low-voltage converter connected to the third DC voltage connector is arranged to generate a low voltage such as approximately 12 V, 24 V or 48 V not only from the first-mentioned, higher voltage range but also from the second-mentioned, lower voltage range.

[0010] The first rated output voltage is at least 750 V (or at least 560 V). Furthermore, the first rated output voltage can be at most 1000 V or alternatively at most 1100 V or 1200 V in order to supply, for example, a battery or a high-voltage vehicle electrical network branch, i.e., generally components that require a high voltage of at least 750 V in at least one state, i.e., a section of its operating voltage range has at least a minimum of 750 V. The relevant components are constructed to operate at an operating voltage of at least 750 V (or 650 V) in at least one state. This is especially the case when the battery has a rated voltage of 800 V, for example, in order to fully charge this battery and reach the maximum state of charge. In the first mode, the changeover switch connects the first DC voltage converter to the first DC voltage connector.

[0011] In the second mode, the changeover switch preferably has a switching state different from that in the first mode. Thereby, a lower voltage (maximum 480 V or maximum 450 V) can be fed through the changeover switch to the second DC voltage connection, so that components or vehicle electrical network branches can be provided at the second DC voltage connection, which can be supplied with power at a maximum of 480 V or maximum 450 V (i.e., designed for a maximum operating voltage = 480 V or 450 V), however they are not constructed for operation at 650 V or 750 V or higher voltages. For example, this is the case for the following electric heating element, which has a rated voltage of, for example, 400 V, however, this electric heating element can also operate without damage at a voltage of 450 V or 480 V, i.e., a component, the maximum allowable operating voltage of which is 10%, 15% or 20% above the rated operating voltage. This is possible in the case of the heating element because, due to its thermal inertia, a brief higher power is acceptable. An electrically operated air-conditioning compressor can also be considered here. In the second mode, the changeover switch connects the second DC voltage connection to the first DC voltage converter.

[0012] Preferably, the charging circuit also includes a configuration circuit. The DC voltage converter is connected to the rectifier through this configuration circuit. The configuration circuit is arranged to connect the DC voltage converters in parallel with each other (in a first configuration) or in series (in a second configuration), and is also connected to the rectifier in this way. Therefore, the configuration circuit is arranged to, in the first configuration, connect the sides of the DC voltage converters facing the rectifier (= their first sides) in parallel with each other, and connect the DC voltage converters in parallel with the rectifier. In addition, the configuration circuit is arranged to, in the second configuration, connect the sides of the DC voltage converters facing the rectifier (= the first sides) in series with each other. The resulting series circuit is connected to the rectifier, where in particular the ends of the resulting series circuit are connected in parallel with the rectifier. Therefore, if the second configuration of the configuration circuit is set, then the DC voltage converters are connected to the rectifier in this series configuration. It can be set that if the DC voltage side output of the rectifier outputs a voltage less than a preset critical value, then (especially by the control device) it is set to the parallel configuration; and if the rectifier outputs a DC voltage greater than this critical value, then it is adjusted to the series configuration. In the first-mentioned case, for example, a relatively low voltage can be generated by the rectifier through single-phase charging, and this voltage is less than the maximum input voltage of the rectifier. In the case of three-phase charging, a higher voltage is generated at the DC voltage side of the rectifier, so that it can be adjusted to the series configuration, where the first side of the DC voltage converter and, if necessary, the intermediate circuit capacitor connected thereto then each only obtain half of the voltage output by the rectifier. The output voltage then lies below the maximum input voltage of the rectifier due to the voltage being divided in half (due to the series connection). The maximum input voltage of the rectifier relates to the corresponding first side, that is, the side connected to the rectifier.

[0013] The configuration circuit can include two switches that respectively connect the potentials of the first sides of the converters to each other to set a parallel connection (for the two potentials). In addition, the configuration circuit can have other switches or diodes or diode circuits by means of which the potentials of the first sides of the DC voltage converters are connected in series with each other, especially when the switches provided for the parallel connection are open. The diode circuit can have two diodes connected in series, and the connection point of them is preferably connected to the neutral conductor connection of the AC voltage connector.

[0014] When switching from a series configuration to a parallel configuration, parasitic capacitance and / or intermediate circuit capacitance can be pre-charged to the voltage generated when changing the configuration, especially the voltage generated before setting the configuration with the aid of the switch. The corresponding pre-charging or discharging significantly reduces the charge balance ("inrush-current"), which is formed by the changed voltage (due to the configuration change). For this purpose, different possibilities of pre-charging or discharging can be envisaged. The control device can be arranged to control a low-voltage converter when changing between the two configurations, and the low-voltage converter is connected to the rectifier via one of the DC voltage converters (especially the second DC voltage converter); to recharge a capacitor that is connected to the DC voltage converter or that exists at the first or second side of the DC voltage converter. This can be a capacitor (intermediate circuit capacitance and / or parasitic capacitance) at the first side (or second side) of the DC voltage converter or at the DC voltage side of the rectifier. This can especially be a capacitor located on the side of the rectifier or on the side of the DC voltage converter (seen from the configuration circuit). This especially relates to the intermediate circuit capacitance at the DC voltage side of the rectifier, i.e., the intermediate circuit capacitance between the rectifier and the configuration circuit. The corresponding recharging is preferably always carried out if the charge state changes on the AC voltage side - i.e., if there is a state transition between the following states: single-phase charging, multi-phase charging, and non-charging, especially a transition between the states of single-phase charging or multi-phase charging.

[0015] Alternatively or additionally, the control device can be arranged to control or activate a charge transfer circuit between the capacitors on both sides of the DC voltage converter for the transfer of charge. The corresponding charge transfer circuit can be passive and include, for example, switches and resistors; or can be active in the sense of a (preferably bidirectional) converter for charge balancing between the capacitors on both sides of the configuration circuit or between the capacitors of different DC voltage converters. In addition, the control device can be arranged to activate a discharge circuit at the capacitor, where this relates to the capacitor connected to the DC voltage converter. In particular, a charge transfer circuit as mentioned above can be provided, which is located between the capacitors on both sides of the DC voltage converter. A charge transfer circuit can also be provided, which is arranged to passively or actively pre-charge or discharge a capacitor (the capacitor connected to the DC voltage side of the rectifier).

[0016] The DC voltage converters can be constructed in the same way. Here, the DC voltage converters are in particular constructed with the same rated power, preferably also with the same components having the same design. The DC voltage converters in particular have the same input voltage range and the same output voltage range, and have diodes with the same conversion ratio. In addition, the DC voltage converters can have the same rated current or maximum current.

[0017] One embodiment provides that at least the DC voltage converter (i.e., the first DC voltage converter) connected to the switching switch is constructed bidirectionally. The control device can be arranged to control the DC voltage converter (which is connected to the switching switch) in a first mode; to generate a voltage at the side of this DC voltage converter (which side is connected to the rectifier).

[0018] At the side of the rectifier where it is connected to the DC voltage converter (i.e., at the DC voltage side of the rectifier), a secondary load connection can be provided. Thereby, a voltage can be tapped at the secondary load connection, and this voltage is also (completely or partially) applied to the first side of the DC voltage converter by means of a configuration circuit. The control device can be arranged to control one of the DC voltage converters (in particular the first DC voltage converter); to convert the voltage at the second side into the voltage at the first side, and then this voltage is fed (directly or via the configuration circuit) to the secondary load connection. If, for example, a battery is connected to the side of the DC voltage converter facing away from the rectifier, then it can output electrical energy to the secondary load connection, i.e., to the DC voltage side of the rectifier, via the relevant DC voltage converter and, if necessary, via the switching switch. This applies in particular to the first DC voltage converter. On the other hand, the rectifier can also be constructed bidirectionally and can be arranged to generate an AC voltage for feed-back from the DC voltage applied to the DC voltage side of the rectifier via an AC voltage connection. Here, electrical energy can be input via the first DC voltage connection, the second DC voltage connection, or the secondary load connection; the control device is arranged to control the relevant energy transfer.

[0019] In particular, it can be provided that the first DC voltage connection is connected to the battery, wherein the first DC voltage converter connected thereto can be provided for converting the voltage from the second side of the converter into the voltage on the first side of the converter (connected to the rectifier) so that at least one secondary load can be supplied via the secondary load connection. The low-voltage vehicle electrical network branch can be connected via the second DC voltage converter to the low-voltage converter. The control device can be configured to control this low-voltage vehicle electrical network branch and transfer electrical energy from the low-voltage vehicle electrical network branch to the secondary load connection, the first side of the second DC voltage converter or the DC voltage side of the rectifier so that the capacitance present there (intermediate circuit capacitance and / or parasitic capacitance) is recharged to the new voltage about to occur, particularly before the configuration circuit changes its state (controlled by the control device) when a configuration change occurs. Components or vehicle electrical network branches can be connected at the second DC voltage connection, wherein this component is preferably not a battery and the connected vehicle electrical network branch does not have a battery, in particular an electric heating element or an electrically operated air conditioning compressor.

[0020] The second side of the DC voltage converter, i.e., the side facing away from the rectifier, can be connected permanently or in parallel with each other via switching elements. Here, one potential of the DC voltage converter is connected to another potential in a switchable manner; thus, the switching element can be of a bipolar configuration. The changeover switch can be combined with such a switching element. In addition, it can be achieved that the changeover switch is not arranged between the second side of the first DC voltage converter and the two DC voltage connections, but is arranged both between the second sides of the DC voltage converter (one side) and between the DC voltage connection and the two sides of the DC voltage converter. Instead of or in combination with the changeover switch (which selectively connects the DC voltage connection to the second side of the first DC voltage converter), a changeover switch device can be provided, which selectively connects the connection of the parallel circuit of the second side of the DC voltage converter to the first and second DC voltage connections. It can be provided that this changeover switch device further has the following functions or switching elements, and the switching elements can purposefully disconnect or establish the parallel circuit between the second sides of the DC voltage converter. Therefore, a changeover switch device can be provided in addition to or instead of the changeover switch, which switchably connects the side of the first DC voltage converter facing away from the rectifier to the side of the second DC voltage converter facing away from the rectifier; and alternatively or additionally, selectively connects this side of the first DC voltage converter facing away from the rectifier to the first or second DC voltage connection. When the parallel circuit of the second side of the DC voltage converter is disconnected, the DC voltage converter can be controlled by the control device in different operating modes (simultaneously). This particularly relates to operating modes with different output voltages or converter powers or duty cycles (for timing within the DC voltage converter). The changeover switch device is also of a bipolar configuration. The side of the first or second DC voltage converter facing away from the rectifier is also referred to as the second side of the relevant DC voltage converter. The opposite side of the DC voltage converter (i.e., the side facing the rectifier) is referred to as the first side of the relevant DC voltage converter.

[0021] The changeover switch and / or changeover switch device can include an electromechanical switching element as the switching element. However, semiconductor switching elements are preferably used to form the changeover switch or changeover switch device. It is also conceivable to use both electromechanical switching elements and semiconductor switching elements, which especially applies to the changeover switch device. In this case, the parallel connection between the second sides of the DC voltage converter is preferably switched by means of the electromechanical switching element, and the selectable connection between the (first) DC voltage converter and the DC voltage connection is formed in a switchable manner by means of the semiconductor switching element. The semiconductor switching element is preferably a transistor, especially a MOSFET or IGBT. The transistor can be used alone as the switching element of the changeover switch or changeover switch device, or can be arranged, for example, as an antiseriell-connected pair of transistors, especially in the case of using transistors with body diodes. The changeover switch or changeover switch device connects the first DC voltage connection to the first DC voltage converter in the first mode; and connects the second DC voltage connection to the first DC voltage converter in the second mode. The switching device is arranged to control the changeover switch or changeover switch device accordingly.

[0022] Furthermore, as shown here, an on-vehicle electrical network with a charging circuit is described. Here, the battery of the on-vehicle electrical network is connected to the first DC voltage connection. The battery is especially a traction battery configured as a high-voltage component. The battery can be a lithium battery. The battery can have a standard operating voltage (rated voltage) of at least 750V or at least 950V, especially approximately 800V. A load of the on-vehicle electrical network can be provided at the second DC voltage connection. This load has a standard operating voltage (rated voltage) different from that of the battery, that is, especially basically half of it (+25% or ±10%). The standard operating voltage (rated voltage) of the load connected at the second DC voltage connection is basically 400V or 420V, for example at least 350V and especially not higher than 500V or 600V. Here, common 400V components can be used as the load. Furthermore, the maximum operating voltage of the load (the maximum voltage determined by the design) (also only temporarily) is preferably higher than 400V, for example approximately 420V, 440V or especially 450V. This is especially the case for electric heating elements because their thermal inertia allows for a higher voltage or higher power for a short time without causing damage to the load. An electric air-conditioning compressor or the like can also be used as the load connected to the second DC voltage connection.

[0023] The battery connected to the first DC voltage connection can generally be the first component, in particular the first load. The battery, for example, acts as a load during the charging process. The load connected to the second DC voltage connection can generally be, in particular, the second component or the second load. This load can also be referred to as a 400V load or a 400V component. The first DC voltage connection can be connected to the secondary load connection (via a switch). The battery can be connected to the secondary load connection (via a switch) and (via another switch) to the first DC voltage connection. The rated voltage of the battery can basically correspond to the voltage at the first DC voltage connection, especially in the first mode; in the first mode, the voltage at the DC voltage connection can be matched to the rated charging voltage of the battery by a first DC voltage converter. If the terminal voltage of the battery exceeds a critical value, then this battery can be connected to the secondary load connection and, in particular, to the first DC voltage connection. If the terminal voltage of the battery does not exceed the critical value, then this battery can be connected to the first DC voltage connection and, in particular, not to the secondary load connection. The switches correspondingly controlled by the control device can be provided for the respective switching devices. The control device is configured to control these connections.

[0024] The component connected to the third DC voltage connection can be called the third component. Here, in particular, a vehicle electrical network branch (as the fourth component) is connected to the third DC voltage connection. The vehicle electrical network branch or the third component is also part of the vehicle electrical network. The standard operating voltage of the vehicle electrical network branch or the third component is at least 750V or at least 950V, especially approximately twice the standard operating voltage of the second load. The standard operating voltage of the component (vehicle electrical network branch) connected to the third DC voltage connection can basically correspond to the standard operating voltage of the first component (the battery at the first DC voltage connection). However, different operating voltages with a maximum deviation of ±10% or ±25% are also possible. The standard operating voltage represents the voltage on which the structure-related component is based and can also be called the rated voltage. The component at the second DC voltage connection can have a rated voltage of 400V or 420V, however, it is preferably configured for a higher maximum operating voltage (e.g., at least 10% or at least 20% higher), such that the component is configured to operate (briefly) at a higher voltage of approximately 440V or 450V.

[0025] The load connected to the second DC voltage connection (i.e., the second component) is preferably an electric heating element. This is in particular an electric heating element of an exhaust gas aftertreatment device (such as an electrically heated catalytic converter), an electric heating element of a cooling circuit of a power electronics device (such as a drive device), an electric heating element of a cooling circuit of an interior space heating device or a window heating device. The vehicle electrical network branch connected to the third DC voltage connection (i.e., the third component) can have a low-voltage voltage converter, which in particular has a subsequent low-voltage component. These low-voltage components are in particular configured for a rated voltage of 12 V (or can also be 24 V or 48 V). Thereby, the vehicle electrical network branch connected to the third DC voltage connection can be a 12 V vehicle electrical network, which has known 12 V electronic components, such as an entertainment system and an on-board computer, or can also have safety-related electronics, such as an anti-lock braking system, a driver assistance system, lighting and the like.

[0026] On the one hand, by means of a charging circuit or by means of the on-vehicle electrical network, the first and second components (i.e., for example, a battery at a first DC voltage connection - especially as a load in the charging mode of the battery) and another load (for example, a heating element at a second DC voltage connection) can be operated simultaneously by means of a changeover switch. Here, the first and second DC voltage connections are alternately connected to a DC voltage converter by means of the changeover switch and are supplied by this DC voltage converter, wherein the respective connection duration and repetition rate of the corresponding DC voltage connection define the effective power of the connected components. Thus, here, the changeover switch can operate according to the rated charging power for the battery and according to the rated power for the second load. The changeover switch can in particular be switched repeatedly (preferably periodically), wherein the duty cycle defines the power output by the corresponding DC voltage connection. Here, the control device can be arranged to adjust the proportion of the rated charging power for the battery and the proportion of the rated power for the second load according to a priority regulation. This can indicate whether the error between the rated charging power and the actual charging power of the battery is minimized, or whether the difference between the rated power and the actual power of the second load is minimized. However, it is also possible to preset targets relating to the two components and thus the two powers: for example, a preset maximum deviation between the rated charging power and the actual charging power and / or a maximum deviation between the rated power and the actual power. In addition, the priority regulation can be time-controlled, for example by means of different time points at which, on the one hand, the battery must be precharged and, on the other hand, the second load must already have generated a certain amount of energy (heat). For example, if a departure date is selected, the battery is fully charged one hour before this date; conversely, the closer to the departure time, the priority shifts in the direction of the second load, i.e., in the direction of the electric heating device, and most of the power is output to the second load in order to bear the charging power. In addition, the control device can be arranged to adjust the duty cycle according to at least one proportion, according to which the changeover switch is switched. The changeover switch defines which part of the total power is output to the first DC voltage connection and defines which part (complementary thereto) has the power transmitted through the second DC voltage connection. As mentioned, the duty cycle can be changed, for example in order to be able to achieve different priorities over time, wherein, however, the operating states of the first and second components can also influence the priority regulation. For example, in a charge state below a minimum critical value, the priority of the second load (i.e., the heating element) can be transferred to the charging of the battery. Description of the Drawings

[0027] Figure 1 For explaining the on-vehicle electrical network and the vehicle-side charging circuit described here. Detailed Description of the Invention

[0028] Figure 1 A charging circuit is shown having connected components K1, K2, K3, where these components can be connected to an external AC voltage source via an AC voltage connector. The AC voltage connector can be configured, for example, as a standardized charging socket. The connected charging circuit has a rectifier whose AC voltage side is connected to the AC voltage connector. The DC voltage side is connected to two DC voltage converters W1, W2 via a configuration circuit KS. The rectifier is connected to the two DC voltage converters W1, W2 via the configuration circuit KS.

[0029] The configuration circuit has two switches which, in the closed state, connect two first sides (i.e., the sides facing the rectifier G) of the DC voltage converters W1, W2 in parallel with each other. In addition, a diode circuit consisting of two series-connected diodes D is part of the configuration circuit. Wherein, in the case of the switches being open, the diodes enable the first sides of the DC voltage converters W1, W2 to be connected in series with each other. A first capacitor C1 is connected to the first side of the first DC voltage converter W1; a second capacitor C2 is connected to the first side of the second DC voltage converter W2. These capacitors are used to smooth the voltage at the first sides of the DC voltage converters W1, W2.

[0030] In addition, the DC voltage converters W1, W2 have second sides facing away from the rectifier G. Further capacitors C1, C2 are connected at these second sides in order to smooth the voltage at the second sides of the DC voltage converters. These capacitors can also be referred to as intermediate circuit capacitors. The same also applies to the capacitors C1, C2. A changeover switch US is connected to the second side of the first DC voltage converter W1 and can be selectively connected to a first DC voltage connector A1 or a second DC voltage connector A2 via the changeover switch. The second side of the second DC voltage converter W2 is connected to a third DC voltage connector A3.

[0031] The secondary load connector is directly connected to the DC voltage side of the rectifier.

[0032] The first component K1 is connected to the first DC voltage connector A1. The first component K1 can be a battery, for example a high-voltage battery, especially a battery having a rated voltage of approximately 800 V or 850 V. The second component K2 is connected to the second connector A2. Here, the second component is preferably a 400 V component configured for a maximum operating voltage of 450 V (also only temporarily). Here, it can be a heating element or also an electric air-conditioning compressor. The component K1 usually has a higher rated voltage than the component K2, especially having approximately twice the rated voltage of the component K2, or it can also only correspond to 180% or 190% of the rated voltage of the second component K2.

[0033] The changeover switch has a two-pole configuration and provides for connection of either of two potentials of a first DC voltage connection or either of two potentials of a second DC voltage connection A2. Additionally, the changeover switch can have a third switching state or mode in which neither the first DC voltage connection nor the second DC voltage connection is connected to the first DC voltage converter W1.

[0034] A third component K3 is connected to a third DC voltage connection. This is in particular a low-voltage converter, for example a converter with a rated voltage of 12 V (or alternatively 24 V or 48 V) provided on its second side (opposite the second DC voltage converter). The low-voltage DC voltage converter can have a first side facing the second DC voltage converter W2 and provided for a rated voltage of at least 800 V or 950 V. A low-voltage vehicle electrical network branch with such a low-voltage DC voltage converter can be provided, which is directly connected to the third DC voltage connection A3. Thereby, the component K3 can be a placeholder for the low-voltage vehicle electrical network branch. In this low-voltage vehicle electrical network branch, there are components (for which the low-voltage converter is provided) such that when setting a matching operating voltage according to the rated voltage of the components, the component K1 is also configured for (briefly) operating voltages higher than the relevant rated voltage. Preferably, a battery, in particular an 800 V battery, is connected to the first DC voltage connection. The second DC voltage connection can be connected to a component (such as a heating element) configured for an operating voltage of approximately 400 V and a maximum operating voltage of approximately 420 V or 450 V. The battery can be damaged when operating at a voltage exceeding the rated voltage, so the battery is preferably not connected to the second DC voltage connection.

[0035] The first rectifier is configured to output a voltage at the 800 V level (as the upper voltage range) and at the 450 V level (as the lower voltage range) on the changeover switch side.

[0036] An electric drive, in particular its inverter and, if necessary, its connected electric motor, an 800V component (such as a heating element or air conditioning compressor designed for this purpose), and / or a high-voltage battery with a rated voltage of 800V can be connected to the secondary load connection (preferably via a disconnect switch). Furthermore, a direct DC charging connection can be connected to the secondary load connection (if necessary via a disconnect switch). This direct DC charging connection is connected to the battery (preferably via its own disconnect switch) to allow direct charging. Since the first DC connection is also connected to the battery (preferably also switchable, in particular via a changeover switch), the battery can be charged via the first DC converter W1, the changeover switch U, and the first DC connection (for example, for pre-charging if the state of charge falls below a critical value), and preferably also via the direct DC charging connection if the state of charge does not fall below the critical value.

[0037] As mentioned, the changeover switch can be arranged between the first and second DC voltage connections A1, A2 (on one side) and the second side of the first DC voltage converter W1. Alternatively or in combination therewith, the changeover switch arrangement can be arranged at the position marked with a cross, i.e., in the parallel connection of the second sides of the DC voltage converters W1, W2.

[0038] The changeover switch can have two or preferably three switching positions, namely a first state in which the first DC voltage terminal A1 is connected to the converter W1; a second state in which the second DC voltage terminal A1 is connected to the converter; and a third state in which neither of the two DC voltage terminals is connected to the first converter. The changeover switch device can also have two states in which the first or second DC voltage terminal is connected to the second side of the DC converter; a further state in which neither of the two DC voltage terminals is connected to the DC converter W1, W2; and a fourth state in which the second side of the first DC converter W1 is disconnected from the second side of the second DC converter W2. In other cases, the second sides of the two DC converters W1, W2 are connected in parallel (two-pole).

Claims

1. A high-voltage charging circuit on the vehicle side, having an AC voltage connector (WA); at least two electrically isolated DC voltage converters (W1, W2) configured as boost choppers and a rectifier (G), by means of which the DC voltage converters (W1, W2) are connected to the AC voltage connector (WA); and having a changeover switch (US), wherein, The high-voltage charging circuit has first and second DC voltage connectors (A1, A2), and the first and second DC voltage connectors are selectively connected to a first DC voltage converter (W1) via the changeover switch (US); and the high-voltage charging circuit has a third DC voltage connector (A3), and the third DC voltage connector is permanently connected to a second DC voltage converter, wherein the high-voltage charging circuit furthermore has a control device (S), and the control device is arranged to, in a first mode, control the DC voltage converter according to a first rated output voltage, the first rated output voltage being at least 750 V and at most 1000 V; and in a second mode, control it according to a second rated output voltage, the second rated output voltage being at most 480 V.

2. The high-voltage charging circuit on the vehicle side according to claim 1, wherein, The DC voltage converters (W1, W2) are connected to the rectifier (G) via a configuration circuit (D, KS), wherein the configuration circuit is arranged to, in a first configuration, connect the sides of the DC voltage converters (W1, W2) facing the rectifier (G) in parallel with each other and connect these sides to the rectifier (G) in this parallel configuration; and is arranged to, in a second configuration, connect the sides of the DC voltage converters (W1, W2) facing the rectifier (G) in series with each other and connect these sides to the rectifier (G) in this series configuration.

3. The high-voltage charging circuit on the vehicle side according to claim 2, wherein, The control device is arranged to control a low-voltage converter when changing between the two configurations, the low-voltage converter being connected to the rectifier (G) via one of the DC voltage converters (W1; W2); to recharge capacitors (C1, C2; Z1, Z2) connected to the DC voltage converter; or the control device is arranged to control a charge transfer circuit for charge transfer, the charge transfer circuit being between the capacitors on both sides of the configuration circuit, or between the capacitors on both sides of the DC voltage converters (W1; W2), or between the capacitors of different DC voltage converters (W1; W2); or the control device is arranged to activate a discharge circuit at the capacitors (C1, C2; Z1, Z2) connected to the DC voltage converters (W1; W2).

4. The high-voltage charging circuit on the vehicle side according to claim 1 or 2, wherein, The DC voltage converters (W1, W2) are constructed in the same way.

5. The high-voltage charging circuit on the vehicle side according to claim 1 or 2, wherein, At least the DC voltage converter (W1) connected to the changeover switch (US) is constructed bidirectionally, and the control device is arranged to control the DC voltage converter (W1) connected to the changeover switch (US) in the second mode; to generate a voltage at the side of this DC voltage converter (W1) connected to the rectifier, wherein a secondary load connector (A) is connected to the side of the rectifier (G) connected to the DC voltage converters (W1, W2).

6. The high-voltage charging circuit on the vehicle side according to claim 1 or 2, wherein, In the second mode, the changeover switch (US) is arranged to alternately connect the first and second DC voltage connectors (A1, A2) to the first DC voltage converter (W1) repeatedly or periodically or according to a preset, variable duty cycle.

7. The high-voltage charging circuit on the vehicle side according to claim 1 or 2, wherein, A changeover switch device is attached to or instead of the changeover switch. The changeover switch device can switchably connect the side of the first DC voltage converter (G1) facing away from the rectifier (G) to the side of the second DC voltage converter (G2) facing away from the rectifier (G), and / or can alternatively be connected to the first or second DC voltage connection (A1, A2).

8. The high-voltage charging circuit on the vehicle side according to claim 1, wherein, The second rated output voltage is at most 450 V.

9. An on-vehicle electrical network having a high-voltage charging circuit on a vehicle side according to any one of the above claims, wherein, The battery (K1) is connected to the first DC voltage connection (A1); the load (K2) is connected to the second DC voltage connection (A2), and the load has a standard operating voltage of substantially 400 V or 420 V; and the on-vehicle electrical network branch (K3) is connected to the third DC voltage connection (A3), and the on-vehicle electrical network branch has a standard operating voltage of at least 750 V.

10. The in-vehicle electrical network according to claim 9, wherein, The on-vehicle electrical network branch has a standard operating voltage of at least 950 V.

11. The vehicle electrical network according to claim 9, wherein, The load (K2) connected to the second DC voltage connection (A2) is an electric heating element of an exhaust gas aftertreatment device, an electric heating element of a cooling circuit of a power electronics device, an electric heating element of an interior space heating device or a window heating device, and the on-vehicle electrical network branch connected to the third DC voltage connection (A3) includes a low-voltage voltage converter, which has a subsequent low-voltage component, and the low-voltage component is connected to the third DC voltage connection (A3) via the low-voltage voltage converter.

12. The vehicle electrical network according to claim 9, wherein, The control device (S) is configured to control the changeover switch according to the rated charging power for the battery and according to the rated power for the second load.

13. The in-vehicle electrical network according to claim 12, wherein, The control device is configured to adjust the proportion of the rated charging power for the battery and the proportion of the rated power for the second load according to a priority rule, and to adjust the duty cycle according to at least one proportion, and to switch the changeover switch according to the duty cycle.

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