DE102019201706A1 - Vehicle-side charging circuit - Google Patents

Abstract

A vehicle-side charging circuit (LS) with a controllable rectifier (V) and a plurality of energy stores (C1, C2; B1, B2) has a configuration circuit (K) that connects the energy stores selectably in a serial or parallel configuration (C1, C2; B1, B2). The multiple energy stores (C1, C2; B1, B2) are connected to the controllable rectifier (V, BG) via the configuration circuit (K). The controllable rectifier (V, BG) has at least one switch cell (Z1-Z3). At least one of the switch cells (Z1-Z3) can be controlled and each has at least one switchable half-bridge branch (SH1-SH3; S1, S3, S5).

Description

Vehicles with an electric drive, that is, vehicles that drive purely electrically and hybrid vehicles, have an accumulator. It is known to transfer electrical power to the accumulator by means of an alternating current charging station in order to charge it. High voltages are used here, so that it is necessary to protect against excessively high contact voltage in order to ensure that a user does not suffer any damage when touching the chassis or other parts of the vehicle in the event of an insulation fault. A danger arises not only from the voltage source of the external charging station, but also from energy storage devices within the on-board network, such as (intermediate circuit) capacitors or a high-voltage accumulator. Mechanisms for the electrical separation of the last-mentioned, vehicle-side components require additional components such as disconnectors, so that it is a task to prevent danger from voltage sources on the vehicle side in a cost-effective manner.

This problem is solved by the subject matter of the independent claim. Further features, embodiments, properties and advantages emerge from the dependent claims, the description and the figures.

It is proposed to equip a charging circuit with a rectifier which has at least one switchable half-bridge branch. The energy stores (from which there is a risk of excessive contact voltage) are connected to the Vienna rectifier via a configuration circuit. By means of the configuration circuit (in particular its switches) and the at least one switchable half-bridge branch, it is possible to disconnect the energy storage device in order to prevent dangerous contact voltage from being transmitted, for example, to chassis parts of a vehicle. In particular, the energy storage device can thereby be separated from an AC voltage connection which is connected to the Vienna rectifier (or to its AC voltage side). The formation of at least one half-bridge branch as a controllable half-bridge branch (instead of implementation using diodes) and the use of switches in the configuration circuit enable the energy storage devices to be efficiently disconnected by putting these switchable components in an open switching state.

The same or slightly modified components are therefore used that are already available for performing a different function. In the case of the switches of the configuration circuit, this other function is the configuration of the energy stores (in parallel or serial configuration). In this regard, the switchable half-bridge branch has, in addition to its isolating function, the rectifying function within the scope of the usual (i.e. rectifying) operation of the Vienna rectifier.

A vehicle-mounted charging circuit is therefore proposed which has a controllable (i.e. active) rectifier. Furthermore, the charging circuit has a plurality of energy stores and a configuration circuit. The configuration circuit connects the energy storage devices in a selectable serial or parallel configuration. The configuration circuit includes switches that are open or closed depending on the selected configuration. Furthermore, the switches of the configuration circuit can have an open state when disconnection is desired or when a corresponding disconnection signal is present. In the latter case, the switches of the configuration circuit are also used to disconnect the energy stores.

The rectifier includes switch cells. The rectifier is preferably designed in a multi-phase manner. Each phase has a switch cell. Each switch cell can be constructed as a full-wave bridge rectifier, in particular when the rectifier is designed as a Vienna rectifier. In an embodiment as a switchable bridge rectifier, each switch cell is designed as a controllable half-bridge branch; there is a half bridge as a switch cell. The bridge rectifier is at least partially controlled, for example in the form of a semi-controlled bridge circuit, especially when designed as a Vienna rectifier. When configured as a bridge rectifier, the switch cells or their half-bridge branches can be controlled. Each switch cell can (preferably in the case of designs as Vienna rectifiers) in particular be designed as a single-phase symmetrical bridge circuit or as a fully controlled bridge circuit. This applies (preferably in designs as Vienna rectifiers) for each of the switch cells.

The controllable switching elements of the switch cells can therefore be set up in a closed state to conduct the current, either in one direction, while the opposite direction is blocked. The switching elements can be set up to block a current flow in both directions in an off state. In particular, semiconductor switches such as thyristors can be considered as controllable switching elements. TRIACs can also be used. When using transistors as controllable switching elements, these are preferably either without an inverse diode or a switching element is formed by a pair of transistors connected in reverse series (with inverse diode) or a switching element is formed by a transistor (with inverse diode) and a downstream diode (individually for each switching element or as a common diode downstream of the switch cells). In particular, MOSFETs or IGBTs come into consideration as transistors.

As mentioned, the switch cells each have at least one switchable half-bridge branch. In a Vienna rectifier, this half-bridge branch is preferably that which faces an AC voltage connection. The AC voltage connection is connected to the configuration circuit via the rectifier. In the case of switch cells of a Vienna rectifier that are designed as full bridges, the other half-bridge arm can be designed as a non-switchable half-bridge arm (made of diodes), or it can also be designed as a switchable half-bridge arm. The last-mentioned half-bridge branch is the one that faces the configuration circuit or is connected to the short-circuit point. With a Vienna rectifier as a rectifier, each switch cell has two half-bridge branches (in particular a first one that faces the AC voltage connection and a second one that faces the short-circuit point, the configuration circuit or the energy storage device), which together also function as a full bridge (or bridge rectifier) can be designated. A first of the half-bridge branches of each switch cell can be provided in an alternating current side of the rectifier designed as a Vienna rectifier, and a second of the half-bridge branches of each switch cell can be provided in a direct current side of the Vienna rectifier. The Vienna rectifier is three-phase in one example. This example can be designed without a neutral conductor connection (of the rectifier and / or the AC voltage connection).

In embodiments in which a Vienna rectifier is used as the rectifier, the switch cells of the Vienna rectifier can either have a half-bridge arm on the AC side (of the rectifier), which is switchable, and a second half-bridge arm (a DC side of the rectifier) which is not is switchable, or can have a half-bridge branch on the AC side, which is switchable. The switch cells can also be on the direct current side, i.e. H. on the side facing the short-circuit point, have a half-bridge branch that is switchable.

In embodiments in which a Vienna rectifier is used as a rectifier, each switch cell of the Vienna rectifier has, as usual, a transistor which is set up to transfer the switch cell (in particular the two ends of each half-bridge branch, i.e. the two DC voltage potentials / output potentials of the rectifier two diodes) when closed. A voltage conversion can be achieved by means of this targeted and preferably clocked short circuit, especially since each memory cell is connected to the AC voltage connection via its own inductance. Each switch cell is also connected to a positive voltage potential via a first diode and to a negative voltage potential via a second diode in each case. In particular, the switch cell or its bridge rectifier (partially or fully controlled) is connected to the DC voltage side of the Vienna rectifier via the diodes. The diodes lead to the configuration circuit. Each switch cell is connected to the two potentials to which the configuration circuit is also connected via two diodes. Inductivities can be connected upstream of the rectifier (in the direction of the AC voltage connection) and / or downstream (in the direction of the energy store).

If, in embodiments in which a Vienna rectifier is used as a rectifier, the switch cell comprises a switchable half-bridge branch and a non-switchable half-bridge branch, the switchable half-bridge branch is connected to the AC voltage connection. In particular, the switchable half-bridge branches of the switch cells are each connected to one phase of the AC voltage connection. If both half-bridge branches are designed to be switchable, the switchable half-bridge branch which is not connected to the AC voltage connection (i.e. the opposite half-bridge branch) is (directly) connected to the short-circuit point. In particular, the connection point between the two switching elements of the half-bridge branch is connected to the short-circuit point.

In embodiments in which a Vienna rectifier is used as the rectifier, the short-circuit point of the Vienna rectifier is connected to the switch cells. This preferably applies to all switch cells of the Vienna rectifier. The short-circuit point thus forms a collection point.

The switch cells of the rectifier each include at least one switchable half-bridge branch. The rectifier can be unidirectional or bidirectional. The switching elements or the semiconductor switching units of the at least one switchable half-bridge branch can preferably be switched bidirectionally, but can - especially with a unidirectional rectifier - be unidirectional switchable. With bidirectional switchability of a switching element or a semiconductor switching unit, the current flow can be switched in both directions through the switching element. If a switching element or a semiconductor switching unit can be switched unidirectionally, the current flow can be switched in one direction (preferably towards the configuration circuit), while the switching element or the semiconductor switching unit blocks in the opposite direction. In a unidirectional rectifier, unidirectionally switchable switching elements or semiconductor switching units are preferably used to represent the at least one switchable half-bridge branch. Such switching elements or semiconductor switching units can be designed to be blocking against the switchable current direction. In a bidirectional rectifier, bidirectionally switchable switching elements or semiconductor switching units are preferably used to represent the at least one switchable half-bridge branch. A switching element or a semiconductor switching unit can be implemented with one semiconductor component or with a plurality of semiconductor components.

For example, a thyristor (in particular a controllably conductive towards the configuration circuit) or a transistor without an inverse diode, such as an IGBT, can be used as a unidirectional switchable switching element (or semiconductor switching unit). Furthermore, a transistor with an inverse diode (such as a MOSFET) can be used as a unidirectional switchable switching element, with which an individual diode or a diode common to several switching elements is connected in series, the reverse direction of which is preferably opposite to the reverse direction of the inverse diode. A unidirectionally switchable switching element (or a corresponding semiconductor switching unit) conducts in a controlled manner in one direction (in particular in the direction of the configuration circuit) and blocks in the opposite direction.

For example, a TRIAC can be used as the bidirectionally switchable switching element, or two transistors connected in anti-parallel without an inverse diode, such as IGBTs, are used. It is possible to use two switchable semiconductor components which are connected in anti-parallel and each block in one direction, for example by not having an inverse diode. It is therefore possible to implement a bidirectionally switchable switching element by means of a thyristor and an IGBT, which are connected in anti-parallel (i.e. which are connected in parallel with one another with opposite flow directions). Furthermore, a bidirectionally switchable switching element can be implemented by means of two transistors, each of which has an inverse diode (such as MOSFETs), these transistors being connected to one another in an antiserial manner. In addition, a bidirectionally switchable switching element can be implemented by means of two semiconductor switch components, each of which has an inverse diode (for example two MOSFETs), these transistors being connected to one another in anti-series.

A unidirectionally switchable switching element (or a corresponding semiconductor switching unit) conducts in a controlled manner in one direction (in particular in the direction of the configuration circuit) and blocks in the opposite direction (uncontrolled). A bidirectionally switchable switching element (or a corresponding semiconductor switching unit) conducts in a controlled manner in one direction and in the opposite direction.

The terms switching element and semiconductor switching unit are used synonymously with one another in this description.

The at least one half-bridge branch can have semiconductor switching units that block against their forward direction. Such semiconductor switching units are referred to as unidirectionally switchable semiconductor switching units. This applies in particular to unidirectional designs of the charging circuit or charging circuits with a unidirectional rectifier.

In another embodiment, the at least one half-bridge branch can have semiconductor switching units that can be switched in both directions. Such semiconductor switching units are referred to as bidirectionally switchable semiconductor switching units. This applies in particular to bidirectional configurations of the charging circuit (i.e. a charging circuit capable of feedback) or charging circuits with a bidirectional rectifier.

It can be provided that the semiconductor switching units each have a thyristor. It can also be provided that the semiconductor switching units have a semiconductor switch with an inverse diode and a diode connected in series with the semiconductor switch. Instead of the term “semiconductor switch with inverse diode”, “semiconductor switch that conducts against the switchable direction” can also be used, especially since the effect is the same and the conductance against the switchable direction of the semiconductor (i.e. the line through the inverse diode) through the series connection of a Diode or by an antiserial, further (similar) semiconductor switch. It can further be provided that the semiconductor switching units each have two semiconductor switches connected in reverse series with one another with an inverse diode or each have one semiconductor switch with an inverse diode which is connected in series with at least one central blocking diode.

It can be provided that the rectifier is a Vienna rectifier which has a short-circuit point to which the switch cells are connected. In the case of a Vienna rectifier, the switch cells, which are connected to the negative and positive potential of the rectifier (or its output side) via further diodes, can have switchable half-bridge branches whose semiconductor switching units are (simple) MOSFETs. In the case of a Vienna rectifier, the at least one switchable half-bridge branch of each switch cell can thus have two MOSFETs connected in series. If the switch cells each have two controllable half-bridge branches (and thus represent a controllable full bridge), then each half-bridge branch can have two MOSFETs connected in series. Semiconductor switches can generally be used which conduct against the controlled current direction, for example due to an inverse diode, with “MOSFET” at this point only being a placeholder for such semiconductor switches.

The rectifier can be designed as a switchable bridge rectifier, in particular as a preferably three-phase three-phase bridge. Its bridge branches, which are also referred to here as half-bridge branches, are formed by the switch cells. The semiconductor switching units can each be formed by a thyristor or by semiconductor switches that conducts against the controllable current direction in connection with a further, antiserial, similar semiconductor switch, or in connection with a diode, the reverse direction of which is opposite to the controllable current direction of the semiconductor (um so to block the conduction against the controllable current direction through the semiconductor switch). The diode or the semiconductor switch of the same type can be present individually for each semiconductor switch or can be present jointly for the semiconductor switches as a common component (for example in the positive and / or negative DC voltage potential of the rectifier).

The switchable half-bridge arm of each switch cell can have two thyristors connected in series. Both switchable half-bridge branches of each switch cell can each have two thyristors connected in series. In general, the at least one switchable half-bridge branch can have two switching elements that conduct current neither in one or the other direction in the open switching state, and either conduct in both directions or in only one direction in the closed switching state, while a current flow in the other direction Is blocked. As mentioned, semiconductor switches such as thyristors are particularly suitable for constructing the switching elements of the switch cells. Furthermore, a switching element can also be formed by means of two transistors which are connected in anti-parallel and which have an inverse diode. Alternatively, it can be provided that a transistor without an inverse diode is used as the semiconductor. Alternatively or in combination with this, a transistor and a diode connected in series can be used as the switching element. The transistor can have an inverse diode.

It can be provided that the switch cells have a non-switchable half-bridge branch. This can be designed from diodes. The non-switchable half-bridge branch is designed in particular with two diodes connected in series via a connection point. The connection point is connected to the short-circuit point. In general, the non-switchable half-bridge branch is connected to the short-circuit point. The non-switchable half-bridge branch is thus facing away from the AC voltage connection. The switchable half-bridge arm faces the AC voltage connection. The switch cells can thus each be designed as a BnHZ circuit (with n = 2 or an even number, in particular twice the number of phases at the AC voltage connection). In this case, a neutral conductor connection of the AC voltage connection can be connected via a switch (preferably a reverse blocking switch such as an electromechanical switch or a reverse blocking semiconductor switch such as a thyristor or a TRIAC), for example to one of several AC voltage connections of the rectifier.

As mentioned, the rectifier can have two (or more) half-bridge branches that are controlled. In other words, both half-bridge branches of the rectifier can be designed in a controlled manner. The result is a B2C circuit (for each switch cell). The switch cells can thus each be designed as a fully controlled bridge rectifier. Here, too, both half-bridge branches or all switching elements of the bridge rectifier are preferably designed as thyristors, but can also be designed as a back-to-back transistor pair (each with an inverse diode) as a transistor without an inverse diode or as a transistor with an inverse diode and a diode connected in series. An embodiment in which each switch cell comprises two switchable half-bridge branches can provide that the two switchable half-bridge branches each have two thyristors connected in series. The switching elements of the bridge rectifier are controllable in one direction and blocking in the opposite direction.

The rectifier can be designed as a preferably polyphase Vienna rectifier. In this case, each switch cell can be designed as a B2C circuit or as a B2HZ circuit, ie it can have two controlled half-bridge branches or have a controlled and an uncontrolled half-bridge branch. Another possibility for representing the rectifier is to design it as an (at least partially) switchable bridge rectifier. Here, at least one half-bridge branch (of several) is designed to be switchable (while at least one non-controllable or current-controlled half-bridge branch exists), or all half-bridge branches are designed to be switchable. When the rectifier is designed as a bridge rectifier, each switch cell is formed by a (separate) half-bridge branch. At least one switch cell is thus preferably switchable, or all switch cells are switchable. The bridge rectifier, which represents the rectifier, can thus be a BnC rectifier or a BnHZ rectifier. The variable n is twice the number of phases of the AC voltage connection and can be 2 or 6, for example. If at least one of the half-bridge branches of the bridge rectifier is not controlled or current-carried (e.g. in the form of a diode half-bridge branch), it can be provided that a neutral conductor connection of the AC voltage connection is connected to an electromechanical switch or to a (reverse blocking or bidirectionally blocking) semiconductor switch. Furthermore, it can be provided that in the case of a three-phase design of the rectifier, the rectifier does not have a neutral conductor connection or is not connected to a neutral conductor connection of the AC voltage connection.

In the embodiment in which each switch cell has a controlled half-bridge branch and a non-controlled half-bridge branch, it is preferably provided that a switching element is provided between the short-circuit point and a neutral conductor connection of the AC voltage connection. In embodiments in which both half-bridge branches of each switching cell are designed in a controlled manner, a neutral conductor connection of an AC voltage connection can be connected to the short-circuit point directly or via a switch.

It can thus be provided that the vehicle-side charging circuit has a neutral conductor connection (in particular as part of the AC voltage connection), the neutral conductor connection being connected to the short-circuit point directly or via a switch.

The energy stores can be designed as intermediate circuit capacitors of a plurality of DC voltage converters. The DC voltage converters connect the configuration circuit or the Vienna rectifier, for example to an on-board network section, a high-voltage accumulator or the like. The DC voltage converters can be designed to be galvanically isolating. The DC voltage converters can be designed in the same way. In one embodiment, two DC voltage converters are provided. Both are preferably designed to be galvanically isolating (in particular by using a transformer in each converter). An intermediate circuit capacitor is provided in parallel to each DC voltage converter (or to the side of the converter which faces the rectifier). With two DC voltage converters, there are thus two intermediate circuit capacitors. A first intermediate circuit capacitor is connected in parallel to a first of the two DC voltage converters, and a second of the intermediate circuit capacitors is connected in parallel to one of the second DC voltage converters. The intermediate circuit capacitors or the DC voltage converters are connected to the configuration circuit. In particular, these are connected to it in such a way that, in the case of different switching states of the configuration circuit, the intermediate circuit capacitors and thus also the DC voltage converters are configured in parallel or in series with one another. This applies in particular to the side of the DC / DC converter that faces the rectifier. The intermediate circuit capacitors are arranged on the side of the DC / DC converter that faces the Vienna rectifier.

Alternatively, the energy stores are designed as accumulator elements of an accumulator. In particular, each accumulator element comprises the same number of cells. The accumulator elements are preferably designed in the same way. An accumulator can thus have several accumulator elements. The accumulator elements can consist of a single cell. Each accumulator element preferably comprises a multiplicity of cells connected to one another in series and / or in parallel. The accumulator elements can be connected in series or in parallel to one another by means of the configuration circuit. This allows the total voltage of the accumulator and also the current strength to be set. The configuration of the accumulator can be set by means of the configuration circuit. The accumulator elements are thus connected to the configuration circuit in such a way that, in different switching states of the configuration circuit, the accumulator elements are connected to one another in parallel or in series. The accumulator is, in particular, a high-voltage accumulator with a nominal voltage of more than 300 volts, more than 350 volts and in particular of approximately 400 volts. The accumulator is in particular a traction accumulator. The accumulator can be designed as a lithium-ion accumulator. Each accumulator element can for example have approx. 100 or approx. 96 lithium cells, which are connected in series with one another.

The charging circuit can also have a fault current detection unit. This can be connected to the switchable bridge arms directly or indirectly (e.g. via a controller). The fault current detection unit is logically connected to the switchable half-bridge branch, while the other half-bridge branch of each switch cell is not designed to be switchable, or the fault current detection unit is logically connected to both controllable half-bridge branches of each switch cell. Furthermore, the fault current detection unit is preferably connected to the configuration circuit in a driving manner. The fault current detection unit is set up to control the switchable bridge branches and the switches of the configuration circuit in the open state when a fault current is detected that is greater than a threshold value. This enables the energy storage devices to be reliably disconnected.

Furthermore, it can be provided that a control is controllably connected to the switchable bridge branches and the configuration circuit. The control can be set up either to detect errors itself or to detect critical states, or it can have an input via which signals can be entered that represent an error or a dangerous situation (crash, insulation fault, ...). The controller is thus set up to control all switchable bridge branches of the rectifier and the switches of the configuration circuit in an open state in the event of a received or detected error. In addition, the controller can be set up to control the configuration circuit according to a desired configuration state. Furthermore, the controller can be set up to control the switchable bridge branches of the rectifier in a normal operating mode in such a way that a rectifying function results. In particular, the controller is set up to control the switchable half bridges in a normal operating mode in such a way that they perform the function of a diode half bridge.

The configuration circuit can have three switches that are connected in series, the outer points of this circuit being connected to the potentials of the DC voltage side of the rectifier, to which the energy storage is also connected at one end, while the two resulting connection points between the switches are connected to each other end of the energy storage is connected.

In one embodiment, the configuration circuit has two switches and two diodes. The switches and the diodes are connected in series. In particular, the two diodes are directly connected to one another. The switches are connected to one another via the diodes. The short-circuit point of the Vienna rectifier is connected to a diode connection point. The diodes of the configuration circuit are connected to one another via this diode connection point. Instead of diodes, semiconductor switches can also be used, which are controlled according to a diode function. The resulting series connection of the diodes and switches of the configuration circuit has two outer ends which are connected to different potentials on the DC voltage side of the Vienna rectifier. Between a first of the two switches and the diodes there is a connection point which is connected to one end of a first of the energy stores. A further connection point, which is connected to one end of the other energy store, results between the diodes or a second one of the switches. The other end of the energy store is connected to the outer ends of the series circuit that results from the diodes and the switches of the configuration circuit. In other words, the other ends of the energy stores are connected to one end of the switch that is not connected to a diode in each case. In other words, the other ends of the energy stores are connected to a DC voltage side of the rectifier or to the two DC voltage potentials that are provided in particular by the rectifier. The switches can be electromechanical switches or semiconductor switches, which can preferably have a bidirectional blocking effect, for example the aforementioned bidirectional or unidirectional (and reverse blocking) switchable switching elements, such as thyristors or a TRIAC. It can be provided that a switch is connected in parallel to the series circuit that is formed by the two diodes of the configuration circuit. A neutral conductor connection (of the AC voltage connection) can be connected to a connection point via which the diodes are connected to one another.

In a further embodiment, the configuration circuit has three switches. The switches are connected to one another in series. The switches are electromechanical switches or semiconductor switches which can preferably have a bidirectional blocking effect, for example the aforementioned bidirectional or unidirectional (and reverse blocking) switchable switching elements, such as thyristors or a TRIAC. In this embodiment, the rectifier is preferably not connected to a neutral conductor connection.

Each switch cell preferably has an AC voltage side that is connected to an inductance. Switch cells with only one controlled half-bridge branch (while the other half-bridge branch is not controlled) are via the controlled half-bridge branch connected directly to the AC voltage side, in particular with an individual AC voltage phase of the AC voltage connection. If each switch cell comprises two controllable half-bridge branches, then one of the two controllable half-bridge branches is connected to an individual phase on the AC voltage side. Each switch cell can also have a DC voltage side. In the case of switch cells with only one controlled half-bridge branch, this is the half-bridge branch which is not controlled and which is designed in particular as a diode half-bridge branch. The DC voltage side of each switch cell is connected to the short-circuit point.

The fault current detection unit mentioned here can be provided in order to detect a fault current in the Vienna rectifier or in the configuration circuit and also in components that are connected to these components.

Preferably the charging circuit is unidirectional, i. H. not designed for feedback. If the energy stores are designed as intermediate circuit capacitors of a plurality of DC voltage converters, the DC voltage converters are designed in particular unidirectional. The DC voltage converters can be designed as buck converters (as synchronous converters or as boost converters). The invention enables the charging circuit to be designed without dedicated disconnectors which would have to be opened in the event of a detected fault current (which is too high).

The charging circuit can be designed for single-phase charging or three-phase charging. In the case of three-phase charging, a switch is preferably opened, which is located between the neutral conductor connection and the short-circuit point. The Vienna rectifier is, in particular, designed to be bidirectional blocking, preferably due to the configuration of the controllable half-bridge branches. It can be provided, for example by designing the control, that the switchable half-bridge branches are opened first when a fault is detected or the fault current is too high, and only then is the configuration circuit set in the open state. If a connection between the neutral conductor connection and the short-circuit point (or the rectifier) comprises a switch (which, when open, separates the neutral conductor connection from the short-circuit point or from the rectifier), each switch cell can, as mentioned above, have a switchable half-bridge branch and a non-switchable one Half-bridge branch can be formed, or can be formed with two switchable half-bridge branches. If a connection between the neutral conductor connection and the short-circuit point or the rectifier does not include a switch (i.e. is designed as a continuous connection), then each switch cell is preferably designed as with two switchable half-bridge branches. In the event of a fault, the switch between the neutral conductor connection and the short circuit, if present, is activated open (preferably by the controller, which is designed for this). In a charge state (in particular in a single-phase charge state) the switch is preferably closed. In a three-phase state of charge, the switch is preferably closed.

Finally, it can be provided that the charging circuit has a discharging circuit. In the event of an error, this can be activated when an error and, in particular, an excessively high error current is detected, the controller being designed to carry this out. In particular, the discharge circuit is activated when the configuration circuit, the switchable bridge branches or both are in the open state.

An impact detection unit can be provided which is set up to determine an impact of the vehicle. Furthermore, this is designed to open the configuration circuit and the switchable bridge branches when the impact is detected (preferably first the configuration circuit and then the switchable bridge branches). For this purpose, the impact detection unit can be connected upstream of the control, or the control comprises a corresponding impact detection unit.

The 1 , 2 and 3 show charging circuits that serve to explain the procedures and embodiments described here. The 1 and 2 relate to exemplary charging circuits with a Vienna rectifier as the rectifier. The 3 relates to an exemplary charging circuit with a switchable bridge rectifier as a rectifier.

The 1 shows a charging circuit LS with an AC voltage connection which has three phases P1, P2 and P3. Furthermore, the AC voltage connection comprises a neutral conductor connection N. In addition to the AC voltage connection, a Vienna rectifier V is provided, which has a three-phase design. The Vienna rectifier comprises three switch cells Z1 to Z3. Each switch cell is connected via two diodes (which are arranged on both sides of the cells). The diodes connect the switch cell to a positive and a negative potential. This potential is a DC voltage potential that can also be viewed as the output potential of the Vienna rectifier.

Every switch cell Z1 to Z3 connects an individual phase P1 to P3 with a common Short-circuit point M. This includes each switch cell Z1 to Z3 in the 1 a controllable half-bridge branch SH1 to SH3. This is in the 1 each formed by means of two thyristors. These are connected in series. The resulting connection point between the thyristors is via an individual inductance 11 to 13th with the phase concerned P1 to P3 connected. In the 1 is the opposite half-bridge branch H1 to H3 not controllable. It comprises two diodes each, which are connected in series, with the resulting connection point being connected to the short-circuit point M. In the 1 an embodiment is shown in which each switch cell has only one controllable half-bridge branch and one non-controllable half-bridge branch. The controllable half-bridge branches are as SH1 - SH3 and the non-controlled half-bridge branches are marked with H1 - H3 designated.

The Vienna rectifier forms a power factor correction filter. The Vienna rectifier has a rectifying function and also includes a step-up function, corresponding to a step-up of a rectified voltage to a (in comparison to this) higher voltage. Each switch cell includes a transistor T1 - T3 (like any common Vienna circuit). This transistor T1-T3 of each cell Z1-Z3 is provided to cause a short circuit (between the respective ends of the half-bridge branches) in a clocked manner. The connection of the switch cells to the AC voltage connection via respective inductances I1-13 results in the possibility of boosting.

A configuration circuit K is connected to the Vienna rectifier V. This comprises two switches SC1, SC2. The configuration circuit K further comprises two diodes KD, which are also connected in series. The two diodes are provided between the two switches SC1, SC2 of the configuration circuit K. The result is a series connection of the two switches SC1 and the diodes KD, the outer ends of this series connection being formed by the two switches SC1, SC2. The outer ends are connected to the two DC voltage potentials which are provided by the Vienna rectifier V. Between the diodes KD and the switches SC1, SC2 connected directly to them, there is in each case a connection point on both sides of the diodes KD. Both of the resulting connection points are connected to different energy stores C1, C2.

Instead of the diodes KD, a switch can also be provided. This switch and the switches SC1 and SC2 can be thyristors (generally: reverse blocking or reverse blocking semiconductor switches) or electromechanical switches. This is especially true for the 1 as well as for the 2 and / or the 3 .

The energy stores C1, C2 shown in the figures are designed as capacitors (in particular as intermediate circuit capacitors) according to the solid lines. As an alternative to the energy stores T1, T2, accumulator elements B1, B2 can be used.

A first of the energy stores C1 or B1, which is connected to the first (positive) direct voltage potential of the rectifier V, is also connected to the opposite potential via one of the two switches. The first energy store C1 or D1 is thus connected directly to the positive direct voltage potential and at the opposite end to the switch SC2, which is connected directly to the second (negative) direct voltage potential. In a comparable way, the other energy store (the second energy store C2 or B2) is directly connected to the second potential (for example a negative potential) and is also connected to the first-mentioned potential (positive direct voltage potential) at the other end via the switch SC1. The energy stores are thus connected to the configuration circuit in a crossover manner. In the closed state of the switches SC1, SC2 of the configuration circuit K, the energy stores are connected in parallel to one another. In an open state they are connected to one another in series (via the diodes KD).

The 1 serves (like the 2 ) to show two variants of energy storage. In a first variant, which is shown with solid lines, the energy stores C1, C2 are provided as intermediate circuit capacitors, which are each connected in parallel to a DC voltage converter DC1, DC2. The DC voltage converters DC1, DC2 are designed to be electrically isolating. The capacitors C1, C2 thus form intermediate circuit capacitors of the DC voltage converters DC1, DC2. Since the intermediate circuit capacitors interact with the DC voltage converters, these together form a DC voltage converter unit and can in particular be viewed as a functional part of the DC voltage converter. The outputs of the DC voltage converters DC1, DC2 are connected to one another in parallel. This results in two output potentials A +, A-, corresponding to the two potentials that result from the parallel connection of the two DC voltage converters. A controller C controls, as shown symbolically, the controllable half-bridge branches SH1 - SH3 and the switches SC1, SC2 of the configuration circuit Kan. In the event of a fault, especially if a fault current detection unit F has detected a fault current that is too high, the controller C is activated to switch the relevant switches SC1, SC2 and the relevant half bridges SH1 - SH3 to be controlled in the open state. This results in a separation of the energy stores C1, C2 from the AC voltage connection B1 - B3 .

A second variant, which is shown in dashed lines, provides that the energy stores are provided as accumulator units B1, B2 of a (common) accumulator. The accumulator units B1, B2 are shown switchable, as can be seen from the symbolic switch. It can be provided that the controller C is set up to open a circuit breaker of the accumulator element B1, B2, in particular when an error is detected or received. In the second variant, the capacitors C1, C2 and the DC voltage converters DC1, 2 are preferably not present; the only energy stores in this case are the accumulator units B1 and B2.

The control can furthermore be provided, depending on the number of active phases at the AC voltage input, depending on the battery voltage or depending on a desired supply voltage, to connect the energy stores C1 or B1 to one another in parallel or in series.

In the 2 a charging circuit is shown which, apart from the following properties, depends on the 1 deviates: In addition to the controllable half bridges SH1 - SH3 there are further controllable half bridges SH4 - SH6. Thus, each of the switch cells comprises Z1 - Z3 in addition a second controllable half-bridge branch SH4 - SH6. That’s the switch cell Z1 - Z3 designed as a fully controlled bridge rectifier. The controllable half-bridge branches (and thus the switches of the fully controlled bridge rectifier are formed in the example shown using thyristors. The other half-bridge branches SH4-SH6 each have a connection point that is connected to the short-circuit point M. The disconnector SN between the short-circuit point M and the neutral conductor connection N is preferably obsolete and can be replaced by a short circuit or by a direct connection between the neutral conductor connection N and the short circuit point M.

Apart from that, the embodiment of 2 Features that are already based on the 1 have been explained. For this reason, no further explanation is given; in the 2 In this regard, the illustrated embodiment has the features that have already been identified (with the same reference numerals) with reference to FIG 1 have been explained.

Finally, it should be noted that in the 1 and 2 the diodes D, which connect the direct voltage potentials of the Vienna rectifier V to the switching cells Z1-Z3, have diodes which correspond to the forward directions of the diodes, the forward directions of the thyristors or the forward directions of the controlled and uncontrolled half-bridge branches. The direction of flow of the diodes and the half bridges is opposite to the direction of voltage between the two potentials on the DC voltage side of the rectifier V. This also applies to the direction of flow of the diodes KD, the configuration circuit K. The transistors T1-T3 connect the diodes D leading to the different direct voltage potentials to one another in a controlled manner. As a result, a short circuit can be provided in a targeted and in particular clocked manner, which leads to the representation of a voltage-converting function by means of the inductances I1-13.

In addition, it should be noted that in the solid variant the energy stores C1, C2 functionally form a DC voltage converter together with the elements DC1, DC2 in order to output a voltage at the connections A +, A-. A high-voltage accumulator can be provided at these connections A +, A-, which in this variant, in which the intermediate circuit capacitors C1 and C2 are designated as energy stores, is not explicitly designated as energy stores. Rather, the energy stores are referred to as those which are connected to the AC voltage connection in an unseparated manner. Since, in this case, the accumulator is on the other side of the galvanically isolating DC voltage converters DC1, DC2, there is no risk of contact voltage from this. Rather, the contact voltage of the intermediate circuit capacitors is suppressed as an energy store according to the invention. When considering the dashed variant, however, the accumulator elements B1 and B2 are to be considered together as an accumulator which, with regard to the invention, is referred to as an energy store. It should be noted here that those energy stores are referred to as those which are electrically connected to the AC voltage connection P1-P3 in an unseparated manner, and from which there can thus potentially arise a risk with regard to an excessively high contact voltage.

The blocks DC1, DC2 are referred to as DC voltage converters, although their intermediate circuit capacitors C1 and C2 are shown separately from them. From a functional point of view, however, the DC voltage converters DC1 and DC2, together with the intermediate circuit capacitors C1 and C2, are to be regarded as DC voltage converters. A detailed circuit-related consideration reveals that the intermediate circuit capacitors C1 and C2 are connected to switching and transformer units which have the reference symbols DC1 and DC2. Since the 1 and 2 However, to serve as a schematic overview, components C1 and DC1 should be used as the first DC voltage converter and components C2 and DC2 together functionally as a second DC voltage converter.

The 3 shows a charging circuit LS with an AC voltage connection, represented by the three phases P1, P2, P3. A bridge rectifier BG is connected as a rectifier to these phases P1 to P3. This includes three switchable half-bridge branches Z1 to Z3. Each of these half-bridge branches comprises two semiconductor switching units S1 to S6. The bridge rectifier BG has a three-phase design and thus comprises three half-bridge branches Z1 to Z3. Each of these two half-bridges comprises two semiconductor switching units S1 to S6 connected in series with one another. The resulting connection point between the semiconductor switching units in each half-bridge branch is connected to a separate phase P1 to P3. Each semiconductor switching unit can be implemented by means of a thyristor. Controllable semiconductor switches can also be used as semiconductor switching units, which are conductive opposite to the direction in which they controllably conduct current, for example due to an inverse diode. Such reverse-conducting semiconductor switches can for example be connected in series with a diode which blocks this current flow in the reverse direction (that is, against the switchable current direction). In the 3 is shown by way of example that a blocking diode SD, which has the desired blocking effect, can be provided in each of the two DC voltage potentials. In this case, the blocking diodes SD are central blocking diodes. Other embodiments provide that each semiconductor switching element has a (reverse conducting) semiconductor switch and a diode connected to it. In this case, each semiconductor switching element comprises a blocking diode, in contrast to in 3 illustrated case in which the semiconductor switches S1 to S6 have common blocking diodes SD. Finally, it is possible for each semiconductor switching unit to have two semiconductor switches which are connected to one another in reverse series and which are conductive in the opposite direction to the controllable direction. A flow of current in the rearward direction can also be avoided in this way.

To the charging circuit shown LS the 3 To be configured bidirectionally, the semiconductor switching units can be configured to be controllable in both directions. In particular, the semiconductor switching units can each be implemented by a TRIAC, or by a (different) pair of reverse-blocking semiconductor switches connected in anti-parallel, or by a pair of reverse-conducting semiconductor switches connected in anti-series, such as MOSFETs or other transistors with inverse diodes.

The bridge rectifier BG is connected via the blocking diodes SD to the configuration circuit K, which is designed as shown above. The other units, that is energy storage C1, C2 or alternatively B1, B2 and the DC voltage converters DC1, DC2, and the controller C and the fault current detection unit F are as here in general or based on the 1 and 2 shown trained. Furthermore, the two output potentials A +, A- exist as in the previously illustrated embodiments and result from parallel-connected connections on the same side of the two DC voltage converters DC1, DC2.

In general, the direction of passage of the blocking diodes and the direction of passage of the relevant semiconductor switching units are opposite to one another. This also applies to the blocking direction.

One possibility is the phases in the 1 to 3 (ie the phases P1 to P3) and the neutral conductor (for example the neutral conductor N der 1 and 2 ) to be provided with blocking elements that can block bidirectionally. Such elements are preferably partially or completely formed by components of the half-bridge branches, by switches of the configuration circuit or by diodes of the configuration circuit, and / or by the blocking diodes.

Claims (15)

Vehicle-side charging circuit (LS) with a controllable rectifier (V), several energy stores (C1, C2; B1, B2) and a configuration circuit (K) that connects the energy stores selectably in a serial or parallel configuration (C1, C2; B1, B2 ), the multiple energy stores (C1, C2; B1, B2) being connected to the controllable rectifier (V, BG) via the configuration circuit (K), the controllable rectifier (V, BG) having at least one switch cell (Z1-Z3) at least one of the switch cells (Z1-Z3) being controllable and each having at least one switchable half-bridge branch (SH1-SH3; S1, S3, S5). Vehicle-side charging circuit (LS) according to Claim 1 , wherein the at least one controlled half-bridge branch has semiconductor switching units (SH1-SH6; S1-S6) which each block against their forward direction. Vehicle-side charging circuit (LS) according to Claim 2 , the semiconductor switching units each having a thyristor, each having a semiconductor switch with an inverse diode and a diode connected in series with the semiconductor switch, each with two semiconductor switches connected in anti-series with one another Have an inverse diode or a semiconductor switch with an inverse diode each, which is connected in series with at least one central blocking diode (SD). Vehicle-side charging circuit (LS) according to one of the preceding claims, wherein the rectifier (V) is a Vienna rectifier which has a short-circuit point (M) to which the switch cells are connected. Vehicle-side charging circuit (LS) according to Claim 4 , the switch cells (Z1-Z3) also having a non-switchable half-bridge branch (H1-H3) which is designed with two diodes connected in series via a connection point, the connection point being connected to the short-circuit point (M). Vehicle-side charging circuit (LS) according to Claim 4 or 5 , the switch cells (Z1-Z3) each having two switchable half-bridge branches and being designed as fully controlled bridge rectifiers. Vehicle-side charging circuit according to Claim 4 , 5 or 6 that has a neutral conductor connection (N) which is connected to the short-circuit point (M) directly or via an electromechanical switch (SN) or semiconductor switch. Vehicle-side charging circuit (LS) according to Claim 1 or 2 , wherein the rectifier (BG) is designed as a switchable bridge rectifier which has at least one half-bridge branch which is formed by the switchable half-bridge branches of the switch cells. Vehicle-side charging circuit (LS) according to one of the preceding claims, wherein the switchable half-bridge branches (Z1-Z3; Z4-Z6) each have two thyristors connected in series. Vehicle-side charging circuit (LS) according to one of the preceding claims, wherein the energy stores are designed as intermediate circuit capacitors (C1, C2) of multiple DC voltage converters (DC1, DC2) or are designed as accumulator elements (B1, B2) of an accumulator, the configuration of which is set with the configuration circuit can. Vehicle-side charging circuit according to one of the preceding claims, which also has a fault current detection unit (F) which is directly or indirectly connected to the switchable bridge branches (SH1-SH6) and to the configuration circuit (K) in a driving manner, and which is set up when a fault current is detected that is greater than a threshold value to control the switchable bridge arms (SH1-SH6) and switches of the configuration circuit (K) according to an open state. Vehicle-side charging circuit according to one of the preceding claims, wherein the configuration circuit (K) has two switches (SC1, SC2) and has two diodes (KD) which are connected in series, the switches (SC1, SC2) via the diodes (KD ) are connected to each other. Vehicle-side charging circuit according to one of the preceding claims, wherein each switch cell (Z1-Z3) has an alternating voltage side which is connected to an inductance (11-13). Vehicle-side charging circuit according to one of the preceding claims, wherein the rectifier has a DC voltage side which is connected to an inductance (11-13). Vehicle-side charging circuit (LS) according to one of the preceding claims, wherein the switchable half-bridge branch (SH1-3) is connected to an AC voltage connection (P1-P3).

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