Combined charging / discharging circuit and vehicle charging circuit with a combined charging / discharging circuit

Abstract

Combined charging / discharging circuit with an energy storage terminal (A+, A-), an energy source terminal (PE, NE), a resistor (R), a series switch (L), a cross-switch (Q), and a controller (C) which is drivingly connected to the series switch (L) and to the cross-switch (Q), which together are designed as a changeover switch, wherein the resistor (R) connects a first potential (A+) of the energy storage terminal to a connection point (P) at which the series switch (L) and the cross-switch (Q) are connected to one another, the series switch (L) in a pre-charging state connects the resistor (R) to a first potential (PE) of the energy source terminal (PE, NE), and the cross-switch (Q) in a discharging state connects the resistor (R) to a second potential (NE) of the energy source terminal (PE, NE), wherein the controller is configured to set the pre-charging state (L1, U1) or the discharging state (Q2, U2),wherein the longitudinal switch (L) and / or the transverse switch (Q) in a connection state connects the first potential (PE) of the energy source terminal (PE, NE) to the first potential (A+) of the energy storage terminal, bypassing the resistor (R), wherein the controller is configured to establish the connection state.

Description

[0001] Electric vehicles, i.e. purely electric vehicles and hybrid vehicles, have a rechargeable battery. It is known to transfer electrical power to the rechargeable battery via a charging station in order to charge it. A converter with an intermediate circuit capacitor is used to adapt to different voltage levels (between the rechargeable battery and the charging station). It is also known to charge this capacitor before the start of the charging process in order to limit current peaks that occur when the charging station is switched on. It is also known to discharge the intermediate circuit capacitor after charging to prevent dangerous contact voltages from emanating from the intermediate circuit capacitor. Finally, it is known that after the charging station is no longer in use, the rechargeable battery is electrically disconnected from a charging interface on the vehicle in order to prevent high voltage emanating from the rechargeable battery at the charging interface.The circuits used for this purpose require several components, particularly switches, which are relatively expensive, partly due to their current-carrying requirements. For example, the publication DE 10 2007 047 713 A1 shows circuits with multiple switching elements for bridging, precharging, and discharging.

[0002] The task is therefore to show a way in which the above-mentioned measures can be implemented cost-effectively.

[0003] This problem is solved by the subject matter of the independent claims. Further features, embodiments, properties, and advantages are revealed by the dependent claims, the description, and the figures.

[0004] It is proposed to provide the separation, pre-charging, and discharging functions using a series switch and a cross switch. This allows the functions to be implemented using only a few components. In particular, different, individual circuits for the different functions are avoided. This results in low implementation costs.

[0005] A combined charging / discharging circuit is proposed. This can implement the functions of precharging (an energy storage device) and discharging (the energy storage device). Furthermore, it is preferably also capable of complete disconnection, for example, by fully opening a series switch. The combined charging / discharging circuit is provided in particular in a vehicle electrical system.

[0006] The combined charging / discharging circuit is equipped with an energy storage connection. This serves for connection to a rechargeable battery, in particular of a vehicle electrical system, and preferably via a converter having an intermediate circuit capacitor. The energy storage connection can be implemented by terminals or plugs. Within the electrical system, which includes the charging / discharging circuit, a converter of the electrical system can be connected to the energy storage connection. This converter includes an intermediate circuit capacitor. An intermediate circuit capacitor is therefore provided within the electrical system. In other words, the energy storage connection is configured to be connected to a rechargeable battery via a converter having an intermediate circuit capacitor. The charging / discharging circuit is configured to precharge or discharge this intermediate circuit. The converter can be a DC-DC converter or an inverter.The converter can be unidirectional or bidirectional.

[0007] There is also an energy source connection. This is intended to be connected to an energy source, in particular to an external energy source. The external energy source can be an electrical supply network or a charging station (which is connected to the supply network). A charging connection can be provided within an on-board electrical system and is connected to the combined charging / discharging circuit via the energy source connection. The charging connection is provided on the vehicle side. The charging connection is arranged in particular in an outer skin of a vehicle. The charging connection can be designed according to a standard for electrical charging. The charging connection can be connected to the energy source connection via a fuse and / or via a circuit breaker and / or via a filter circuit. Alternatively, the energy source connection forms the charging connection, which can in particular be designed as mentioned above.

[0008] The combined charge / discharge circuit also includes a resistor, a series switch, and a cross switch. These are located between the energy source terminal and the energy storage terminal. The resistor serves to limit the current for precharging and discharging. The resistor can have a resistance of at least 100 ohms, preferably at least 1 kOhm, at least 10 kOhm, or at least 100 kOhm.

[0009] The charging / discharging circuit also has a controller. This is designed as a device, in particular as a processor with associated software (stored in a memory). Alternatively, the controller can also be hard-wired and / or implemented using discrete electrical components, for example, using (hard-wired, programmable, or non-programmable) logic circuits. The controller is connected to the series switch and the cross switch for control purposes. The controller can have corresponding outputs that are connected to corresponding control inputs of the switches. The switches are electromechanical switches and / or semiconductor switches, such as MOSFETs or IGBTs.

[0010] The resistor connects a first (supply) potential of the energy storage connection (e.g., the positive potential) to a connection point. The series switch and the cross-switch are connected to each other at this point. Both the series switch and the cross-switch branch off from the connection point. One of the two ends or terminals of these two switches is connected to each other at the connection point. In this context, "connected" means that a direct electrical connection exists, which is, in particular, switch-free and / or resistance-free.

[0011] The switches can assume different switching positions (controlled by the controller). Different switching positions result in different connections (open or closed), which also includes a disconnection (i.e., a connection of a switch terminal to an unconnected contact or connection point of the switch, or no connection to a contact or connection point of the switch).

[0012] In a pre-charge state, the longitudinal switch connects the resistor to a first potential of the energy source terminal, preferably to the positive potential of the energy source terminal.

[0013] In a discharge state, the cross-switch connects the resistor to a second potential of the energy source terminal (in particular, to the negative potential of the energy source terminal). The energy source terminal is, in particular, a DC voltage terminal. This also applies to the energy storage terminal. A rectifier can be provided between a charging terminal and the energy source terminal.

[0014] The controller is configured to set the precharge state or the discharge state. The controller is configured to set these states sequentially. The controller is configured to prevent both states from being set simultaneously.

[0015] According to one embodiment of the circuit, the longitudinal switch and / or the transverse switch, in a connected state, connects the first potential of the energy source connection to the first potential (preferably the positive potential) of the energy storage connection, bypassing the resistor. The controller is configured to establish the connected state. This embodiment relates to variants of the charging / discharging circuit in which the energy source connection is connected to the energy storage connection via the longitudinal switch and / or the transverse switches, without this connection between these two connections including the resistor, but rather at least one of the switches is configured in a switching state to connect the connection point to the first potential of the energy storage connection. This results in a direct connection. The switches or switching positions used for this purpose are designed for higher power orequipped with a higher current carrying capacity than switches and / or switch positions which, in the connected state, are not part of the connection resulting between the energy storage connection and the energy source connection.

[0016] The cross-switch can have a switching position in which the cross-switch bridges the resistor. The controller controls the cross-switch to assume this position in the connected state. The cross-switch connects the connection point to the (positive) potential of the energy storage connection. The longitudinal switch also has a switching position in which it connects the connection point to the (positive) potential of the energy source connection. As a result, the connection point receives the potential of the energy source connection, while the cross-switch passes this potential past the resistor to the energy storage connection. It is provided that the controller also sets the longitudinal switch in this switching position in the connected state. It can be provided that this switching position is also set in another state, for example, in the pre-charging state. An example of a corresponding embodiment is shown in theFig. 1 shown.

[0017] Furthermore, it can be provided that the longitudinal switch has a switching position in which the longitudinal switch bridges the resistor when it assumes this switching position. The controller is configured to control the longitudinal switch in the connected state to assume this position. This switching position is, in particular, directly connected to the (positive) potential of the energy storage connection. In this embodiment, it is provided that the longitudinal switch has a first contact or application point that is (directly) connected to the connection point, and a further contact or application point that is connected to the (positive) potential of the energy storage connection. The positive potential of the energy storage connection is also referred to as the first potential. The positive potential of the energy source connection is also referred to as the first potential. An example of a corresponding embodiment is described in Fig. 2 shown.

[0018] Finally, it can be provided that the first switch assumes a switching position in the connected state in which the connection point is connected to the (positive) potential of the energy source connection via the series switch. In this embodiment, a bypass switch is connected in parallel with the resistor. In this embodiment, energy is transferred via the bypass switch and thus not via the resistor via the charging / discharging circuit. The vast majority of the current flows via the bypass switch, so that the current is not limited by the resistor. The cross switch is preferably open in the connected state (in this embodiment). The bypass switch can in particular be designed as a thyristor. The forward direction of the thyristor preferably points towards the energy storage connection.The bypass switch may also generally comprise an electromechanical switch or a semiconductor switch (such as a MOSFET or IGBT), which in particular has a diode junction in the forward path whose forward direction points toward the energy storage terminal. A corresponding example of this embodiment is shown in FIG. Fig. 3 shown.

[0019] Since the charging / discharging circuit can also be provided in a connection state, ie, a state in which the connection between the energy storage terminal and the energy source terminal is a direct connection (without passing through the resistor), the charging / discharging circuit can also be referred to as a combined charging / direct connection / discharging circuit.

[0020] An embodiment, an example of which is shown in Fig. 1, provides that the controller is configured to control the longitudinal switch and the transverse switch according to a connection state in which the longitudinal switch connects the first potential of the energy source terminal to the connection point. In this connection state, the transverse switch connects the connection point to the first potential of the energy storage terminal.

[0021] Another embodiment, an example of which is shown in Fig. As shown in Figure 2, the controller is configured to control the series switch according to a connection state in which the series switch directly connects the first potential of the energy source terminal to the first potential of the energy storage terminal. In this case, the series switch bridges the resistor and, in particular, short-circuits the first potential of the energy source terminal to the first potential of the energy storage terminal.

[0022] In a further embodiment, an example of which is shown in Fig. 3, the combined charging / discharging circuit has a bypass switch. This connects the connection point to the first potential of the energy storage connection. The controller is configured to control the series switch and the bypass switch according to a connection state. In this connection state, the series switch connects the first potential of the energy source connection directly to the connection point. In this connection state, the bypass switch connects the connection point to the energy storage connection, in particular to its first potential. In other words, in the connection state, the bypass switch connects the series switch to the energy storage connection, in particular to its first potential. In the connection state, the bypass switch bridges the resistor. This is also where its name comes from.The series switch is preferably an on / off switch with only two switching positions, in which it disconnects the energy source connection from the connection point or connects them. The bypass switch is also preferably an on / off switch with only two switching positions, in which it disconnects the connection point or the series switch from the energy storage connection, or connects them. The bypass switch is, for example, a thyristor. This preferably has a conduction direction pointing toward the energy storage connection. In particular, the thyristor has a conduction direction pointing away from the energy source connection.This ensures that when charging an energy storage device connected to the energy storage terminal (directly or indirectly), energy can flow from the energy source terminal to the energy storage terminal, since the forward direction corresponds to the corresponding current direction, provided the thyristor is driven in an ON state. The ON state is set when the connection state is provided.

[0023] Furthermore, the longitudinal switch and the transverse switch are jointly configured as a changeover switch. The longitudinal switch and the transverse switch have a common point, namely the connection point. A connecting element of the changeover switch connects the connection point to the first potential of the energy source connection in a first position and, in a second state, the connection point to the second potential of the energy source connection. The longitudinal switch and the transverse switch have a common connection and can, in particular, have a common, operable switching element that adjustably connects the connection point to the first and second potentials of the energy source connection.

[0024] The second, in particular negative, potential of the energy source terminal is preferably directly connected to the second, in particular negative, potential of the energy storage terminal. The series switch is provided in a positive voltage rail of the circuit, wherein the rail connects the first potential of the energy storage terminal to the first potential of the energy source terminal (switchable via the series switch). Also provided in this rail is the resistor, which is provided in series with the rail (as is the series switch).

[0025] The circuit described here can also be provided for disconnection, in particular for separating the energy storage connection from the energy source connection. In this case, the longitudinal switch can have a disconnection switch position. In this position, the longitudinal switch disconnects the first potential of the energy source connection from the connection point and from the energy storage connection. The controller is configured to control the longitudinal switch in the disconnection switch position in a disconnection state.

[0026] One embodiment provides that the longitudinal switch has a first switching element which, in the connected state, directly connects the first potential of the energy source terminal to the first potential of the energy storage terminal. The longitudinal switch preferably has a second switching element. In the pre-charge state, the second switching element is configured to connect the connection point to the first potential of the energy source terminal. This differs from the first switching element. The first and second switching elements are two individual switching elements. The first and second switching elements are different. The first and second switching elements are preferably each switches with two switching positions, i.e., with an ON state and an OFF state. The first and second switching elements are preferably designed differently.The first switching element preferably has a higher current-carrying capacity, a higher switching current, and / or a higher holding current than the second switching element. The first switching element can be designed as a power component. The second switching element can be designed as a low-current component or as a signal component. The current-carrying capacity, the switching current, and / or the holding current of the second switching element is no more than 10%, 1%, or 0.1% of the current-carrying capacity, the switching current, and / or the holding current of the first switching element. The second switching element is designed to be weaker than the first switching element. This allows the second switching element to be manufactured more cost-effectively.

[0027] The first switching element can have a higher current-carrying capacity, a higher switching current, and / or a higher holding current than the cross-switch. The cross-switch can be designed as a low-current component or as a signal component. The current-carrying capacity, the switching current, and / or the holding current of the cross-switch is no more than 10%, 1%, or 0.1% of the current-carrying capacity, the switching current, and / or the holding current of the first switching element. The cross-switch is designed with a lower current than the first switching element. This allows the cross-switch to be manufactured more cost-effectively. The cross-switch and the second switching element can be implemented together as a changeover switch.

[0028] The cross-switch is different from the first switching element. The first and the cross-switch are two individual switching elements. The first switching element and the cross-switch are different. The first switching element and the cross-switch are preferably each switches with two switching positions, i.e., with an ON state and an OFF state. The first switching element and the cross-switch are preferably designed differently. The current-carrying capacity of the cross-switch and / or the second switching element is designed according to the maximum current resulting from the resistor as a current-limiting element.

[0029] Furthermore, a vehicle charging circuit is described which comprises the charging / discharging circuit described here. The vehicle charging circuit comprises a charging interface, in particular in the form of the charging connection described above. The vehicle charging circuit further comprises a converter (for example a voltage converter), in particular a DC-DC converter or an inverter. The charging interface is connected to the converter via the combined charging / discharging circuit. The converter (in particular designed as a voltage converter or also designed as an inverter) has an energy storage device in the form of an intermediate circuit capacitor. This is connected directly or indirectly (generally: galvanically conductively) to the energy storage connection. The combined charging / discharging circuit is thus provided to discharge or precharge the intermediate circuit capacitor.Furthermore, this combined charging / discharging circuit is designed to isolate the converter's intermediate circuit capacitor from the energy source connection. Furthermore, the combined charging / discharging circuit connects the energy source connection (via the converter) directly to the energy storage device, bypassing the resistor.

[0030] In a discharge state, the controller triggers the cross-switch to connect the connection point to the second potential of the energy source connection or to connect the connection point to the second potential of the energy storage connection. This allows the intermediate circuit capacitor to be discharged via the resistor. In this case, the series switch is open. The series switch separates the first potential of the energy source connection from the connection point (and also from the energy storage connection).

[0031] In the pre-charge state, the series switch connects the first potential of the energy source terminal to the connection point, and thus, via the resistor, to the first potential of the energy storage terminal. In one embodiment having the bypass switch, the bypass switch is controlled in an open state, so that the current is limited via the resistor. In the pre-charge state, the cross switch is open, i.e., has a switching position in which it separates the connection point from the second potential of the energy source or energy storage terminal. In particular, in this switching position, the connection point is not connected to the first potential of the energy storage terminal via the cross switch. In the Fig. 1 to 3 show various embodiments of the charging / discharging circuit described here.

[0032] In the Fig. 1 shows an embodiment in which a longitudinal switch L connects the first potential, ie the positive potential PE of the energy source terminal EA, to a connection point P, provided that the switching position L1 of the longitudinal switch L is provided. In a switching position L2 of the longitudinal switch, it is open, so that the first potential of the energy source terminal is not connected to other components of the circuit shown. Fig. In the embodiment shown in Figure 1, the longitudinal switch comprises only these two switching positions, ie a closed switching position in which the first potential PI of the energy source terminal is connected to the connection point P, and an open switching position.

[0033] A cross-switch Q connects the connection point P to a second potential, i.e., the negative potential NE, of the energy source terminal. In a first switching position Q1, the cross-switch Q is open, so that the connection point P is not connected to other components of the circuit shown via the cross-switch. In a second switching state Q2, the cross-switch connects the connection point P to the second potential NE of the energy source terminal EA. In a third switching position Q3, the cross-switch connects the connection point P to the first potential of the energy storage terminal.

[0034] The resistor R serves to limit the current and connects the connection point P to the first terminal of the energy source terminal.

[0035] The energy source connection is formed by the positive (first) potential A+ and the negative (second) potential A-, which is shown on the right. A controller C controls both the series switch and the cross-switch, as schematically shown by the arrows. In the precharge state, the series switch L is in switch position L1 and the cross-switch Q is open (i.e., in switch position Q1). The current fed via PE is limited by the resistor R, and a capacitor connected to A+, such as an intermediate circuit capacitor, can thus be precharged.

[0036] In the discharge state, the cross-switch Q is closed, i.e., in the switch position Q2, in which it connects the connection point (and thus the resistor R) to the second potential of the energy storage connection or the energy source connection. In this case, the two potentials of the energy storage connection are connected to each other via the resistor R (and the cross-switch). No short circuit occurs; instead, the resistor R limits the current flowing between the two potentials A+ and A-.

[0037] In the connected state, ie in switch position L2, the longitudinal switch L is the Fig. 1 is closed, and the cross-switch Q is in the switch position Q3. In this switch position Q3, the cross-switch Q connects the connection point P (and thus the longitudinal switch L) with the first potential A+ of the energy storage connection. In this case, the cross-switch Q bridges the resistor R. This allows a direct connection to be established, which leads through both switches (the switches with the reference symbols L, Q). The resistor R is bridged here, so that the current is not limited by it. It should be noted that in the Fig. 1 the cross-switch Q has three switching positions, i.e. a first Q1 with an open state, a switching position Q2 in which it connects the connection point P with the second potential NE of the energy source connection EA, and a third switching position Q3 in which the cross-switch Q (alone) bridges the resistor R. In comparison, the longitudinal switch L has only two switching positions (L1, L2).

[0038] In the Fig. 2, the cross-switch Q has only two switching positions, namely the switching position Q1, which corresponds to an open cross-switch Q, and a closed switching position Q2, in which the connection point P is connected to the second potential of the energy source terminal EA. In contrast to this (and to the embodiment of Fig. 1) the longitudinal switch L has, in addition to the switch positions L1 and L2 (cf. Fig. 1) has a third switching position L3. The switching positions L1, L2 of the Fig. 2 correspond to the switching position L1 and L2 of the Fig. 1. In the third switching position L3 of the longitudinal switch L of the Fig. 2, this connects the first potential PE of the energy source connection EA with the first potential A+ of the energy storage connection. In the switch position L3, the longitudinal switch L bridges the resistor R. In the pre-charge state, the switch L assumes the switch position L1 and the cross-switch Q is open in the switch position Q1. In the discharge state, the cross-switch Q is closed and assumes the switch position Q2. The longitudinal switch L is preferably in the second switch position L2. In this state, the resistor R connects the two potentials A+, A- of the energy storage connection via the cross-switch Q. In the connected state, the switch L has the switch position L3. The cross-switch Q is preferably open (i.e. in position Q1). Via the switch position L3, the longitudinal switch L connects the first potential PE of the energy source connection with the first potential A+ of the energy storage connection.This results in a direct current path, bypassing the resistor R.

[0039] In the Fig. 3 shows a longitudinal switch L and a transverse switch Q. Both have only two switching positions, namely an open switching position and a closed switching position. The closed switching position is marked U1 for the longitudinal switch L and U2 for the transverse switch Q. The longitudinal and transverse switches together form a changeover switch U, as they are alternately open or closed. Thus, the same connecting element can be used as the setting element for the switch L and the switch Q, particularly in the case of an electromechanical switch as a changeover switch U. The resistor R connects the connection point P to the first potential of the energy storage connection A+. A bypass switch T (here exemplified as a thyristor) bridges the resistor R. The bypass switch T can be controlled in the closed or open state. The controller C is set up to control the bypass switch T.In the precharge state, the longitudinal switch L is in position U1 and the cross switch Q is open. In other words, the changeover switch U connects the resistor R to the first potential PE of the energy source terminal EA. In the discharge state, the changeover switch U is in the switch position U2, i.e., the cross switch Q is in the switch position U2 and the longitudinal switch L is open. In this state, the changeover switch connects the resistor R and the connected connection point P to the second potential of the energy source terminal or the energy storage terminal.

[0040] In the Fig. Figure 3 shows that the changeover switch U also includes the connection point P, to illustrate that the longitudinal and transverse switches L, Q can be provided together as a switch (changeover switch), i.e., in the sense of a single component having two (different) closed positions, namely U1 and U2. In both cases, the current flows via the connection point P, so that the connection point P corresponds to the changeover switch terminal, which is fixed, while the opposite terminal has two selectable contacts. In the connected state, the bypass switch T connects the connection point P to the first potential of the energy storage terminal A+.

[0041] The Fig. 1 to 3 have comparable elements which are designated by the same reference numerals.

[0042] In one embodiment, the charging / discharging circuit is according to Fig. 2. In this case, the switch L comprises a thyristor, an IGBT, a MOSFET or another power semiconductor or also an electromechanical on / off switch which is formed between the first potential PE and the switching position L3. This (first) switching element is formed as a power element and has a current carrying capacity of at least 10 amperes, 100 amperes or 200 amperes. In this embodiment, it can be provided that the longitudinal switch L has a further (second) switching element which is formed as an on / off switching element. This can also be a semiconductor switch or an electromechanical switch. The second switching element is not formed as a power element. Instead, it can be formed with a lower current carrying capacity than the switching element between L3 and PE.The cross-switch Q can also be designed with an on / off switching element that has a higher current carrying capacity than the (first) switching element between PE and L3. In particular, the (first) switching element between PE and L3 is a thyristor. Since a high current (and thus not limited by the resistance) only flows in the connected state, the design for high currents is only necessary for the connection between PE and L3, i.e. for the first switching element. Thus, the first switching element between PE and L3 can be designed as a power switch, while the second switching element between PE and L1 can be designed as an on / off switch with a lower current carrying capacity in comparison. In this case, a transistor, for example, is sufficient for the second switching element, the current carrying capacity of which is designed according to the maximum possible current flowing through R.Since the resistor R has a current-limiting effect, this results in an upper limit for the current that can flow between P and L1, or between P and Q2. Therefore, the switching element between P and Q2 of the cross-switch Q can also be designed with a comparatively low current-carrying capacity (compared to the switching element between PE and L3).

[0043] In the embodiment of the Fig. 1, an on / off switching element can be provided between PE and L1 as a series switch with a high current carrying capacity, whereby the connection between P and Q3 of the cross-switch Q is also designed as a switching element with a high current carrying capacity. The connection between P and Q3, shown and switchable via the cross-switch Q, has a comparatively low current carrying capacity. The relative terms "low" and "high" refer to the comparison between the different switching elements.

[0044] In the Fig. 2, as mentioned, only the on / off switching element between P and L3 of the longitudinal switch L can be provided as a switching element with high power, while the switching element of the longitudinal switch L between PE and L1 and the cross switch Q between P and Q2 can be designed with a lower power. Furthermore, the longitudinal switch L of the changeover switch U of the Fig. 3 preferably also designed as a high power switch, as is the bypass switch T for (compared to the switch Q of the Fig. 3) is designed for high power. As mentioned, the switch Q of the changeover switch U can be designed for low power. Instead of the bypass switch T, another power switching element can also be provided, for example, a power semiconductor or an electromechanical switch.

[0045] Thus, according to the Fig. 2, it can be provided that the switch L has two switching elements with different current carrying capacities. The first switching element between P and L3 has a higher current carrying capacity than the switching element between P and L1. The switching elements are provided as on / off switches. The switching position L2 results when both switching elements are switched off. By designing the switching element between P and L3 as a power component, it is possible to carry a high current between PE and A+, while due to the low current carrying capacity of the switching element of the longitudinal switch L between PE and L1, costs can be saved because this switching element can be equipped with a lower current carrying capacity.

[0046] What has been said for the “current carrying capacity” also applies to the “switching current” and / or “holding current” values.

[0047] An example of the Fig. 1 or Fig. 3, it is provided that instead of the longitudinal switch, a disconnector is provided in the vehicle electrical system between the first potential of the energy source connection and the charging interface, wherein the control is configured to control the disconnector instead of the longitudinal switch.

[0048] The control system can be configured to execute a switching sequence: When switching to the pre-charging state, the cross-switch is preferably opened first (see switch position Q1 or the position of the cross-switch opposite position U2 in the figures). The longitudinal switch is then closed, depending on the setting of switch position L1 or U1 in the figures. The control system is configured to execute the setting and switching, as well as the opening and closing (by appropriately controlling the switches or switching elements).

[0049] The control system can also be configured to carry out a further switching sequence: If the connection state is changed, the cross switch is opened first before the longitudinal switch is set, ie before the longitudinal switch is closed or the switch position L1 (in embodiments of the Fig. 1), L3 (in embodiments of the Fig. 2) or U1 (in the case of embodiments of the Fig. 3) is set. The control system is configured to perform setting and switching, as well as opening and closing (by appropriately controlling the switches or switching elements).

[0050] Furthermore, the controller can be configured to set the pre-charge state before the connection state. Finally, the controller can be configured to establish the discharge state after the disconnection state (in particular, followed by a re-setting of the disconnection state). It can be provided that the discharge state is set before the disconnection state.

Claims

[1] Combined charging / discharging circuit with an energy storage terminal (A+, A-), an energy source terminal (PE, NE), a resistor (R), a series switch (L), a cross-switch (Q) and a controller (C) which is connected in a driving manner to the series switch (L) and to the cross-switch (Q), which together are designed as a changeover switch, wherein the resistor (R) connects a first potential (A+) of the energy storage terminal to a connection point (P) at which the series switch (L) and the cross-switch (Q) are connected to one another, the series switch (L) in a pre-charging state connects the resistor (R) to a first potential (PE) of the energy source terminal (PE, NE) and the cross-switch (Q) in a discharging state connects the resistor (R) to a second potential (NE) of the energy source terminal (PE, NE), wherein the controller is configured to set the pre-charging state (L1, U1) or the discharging state (Q2, U2),wherein the longitudinal switch (L) and / or the transverse switch (Q) in a connection state connects the first potential (PE) of the energy source terminal (PE, NE) to the first potential (A+) of the energy storage terminal, bypassing the resistor (R), wherein the controller is configured to establish the connection state. [2] Combined charging / discharging circuit according to claim 1, wherein the controller (C) is arranged to control the longitudinal switch (L) and the transverse switch (Q) according to a connection state (L1, Q3) in which the longitudinal switch (L) connects the first potential (PE) of the energy source terminal to the connection point (P) and in which the transverse switch (Q) connects the connection point (P) to the first potential (A+) of the energy storage terminal. [3] Combined charging / discharging circuit according to claim 1, wherein the controller (C) is arranged to control the longitudinal switch (L) according to a connection state (L3) in which the longitudinal switch (L) connects the first potential (PE) of the energy source terminal directly to the first potential (A+) of the energy storage terminal. [4] Combined charging / discharging circuit according to claim 1, further comprising a bypass switch (T) connecting the connection point (P) to the first potential (A+) of the energy storage terminal, wherein the controller (C) is configured to control the series switch (L) according to a connection state (U1) in which the series switch (L) directly connects the first potential (PE) of the energy source terminal to the connection point (P) and the controller (C) is configured to control the bypass switch (T) according to an ON state in which the bypass switch (T) directly connects the connection point to the first potential (A+) of the energy storage terminal. [5] Combined charging / discharging circuit according to one of the preceding claims, wherein the longitudinal switch (L) has an isolating switching position (L2) in which the longitudinal switch (L) separates the first potential (PE) of the energy source terminal from the connection point (P) and from the energy storage terminal (A+, A-), wherein the controller is arranged to control the longitudinal switch (L) in the isolating switching position (L2) in a disconnecting state. [6] Combined charging / discharging circuit according to claim 3, wherein the longitudinal switch (L) has a first switching element which, in the connection state (L3), directly connects the first potential (PE) of the energy source terminal to the first potential (A+) of the energy storage terminal, and the longitudinal switch has a second switching element which, in the pre-charging state, connects the connection point (P) to the first potential (PE) of the energy source terminal (EA), wherein the first switching element has a higher current carrying capacity, a higher switching current and / or a higher holding current than the second switching element. [7] Combined charging / discharging circuit according to claim 6, wherein the first switching element has a higher current carrying capacity, a higher switching current and / or a higher holding current than the cross switch. [8] Vehicle charging circuit with a combined charging / discharging circuit according to one of the preceding claims, a charging interface and a voltage converter, wherein the charging interface is connected to the voltage converter via the combined charging / discharging circuit, wherein the voltage converter has an energy storage device in the form of an intermediate circuit capacitor which is connected directly or indirectly to the energy storage connection.

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