Power controller circuit with optimized power losses

Abstract

A power controller circuit has a plurality of switching elements (1, 2) that each have a first and a second load terminal (3, 4) and a control terminal (7). The first load terminals (3) are connected to one another. The second load terminals (4) are also connected to one another. The control terminals (7) are connected to an output (10), which is common for the control terminals (7), of a driver circuit (11) by way of a respective connecting line (9). A switch (12, 12', 12") is arranged in at least one of the connecting lines (9) such that a control signal (C) output by the driver circuit (11) via the output (10) is or is not delivered to the corresponding control terminal (7) depending on whether the respective switch (12, 12', 12") is in an on state or in an off state. The power controller circuit has a control circuit (13) that generates a respective additional signal (Z, Z', Z") that is delivered to the respective switch (12, 12', 12") and, based thereon, the respective switch (12, 12', 12") is changed to the on state or to the off state. The respective switch (12, 12', 12") is changed from the on state to the off state only when the switching elements (1, 2) are in an off state owing to the control signal (C) output by the driver circuit (11).

Description

[0001] Description

[0002] Power loss-optimized current controller circuit

[0003] The present invention is based on a current controller circuit,

[0004] - wherein the current control circuit comprises a switching element having a first and a second load terminal and a control terminal,

[0005] - wherein the control terminal is connected to an output of a driver circuit by means of a connecting line,

[0006] - wherein the current controller circuit comprises a plurality of switching elements, each having a first and a second load terminal and a control terminal,

[0007] - wherein the first load terminals are connected to each other and the second load terminals are connected to each other,

[0008] - wherein the control terminals are connected by means of a respective connecting line to an output of a driver circuit which is common to the control terminals,

[0009] - wherein a switch is arranged in at least one of the connecting lines, so that a control signal output by the driver circuit via the output is supplied to the corresponding control terminal or not, depending on whether the respective switch is in a switched-on or a blocked state, and

[0010] - wherein the current controller circuit has a control circuit which generates a respective additional signal which is fed to the respective switch and on the basis of which the respective switch is switched into the switched-on or blocked state.

[0011] A current controller circuit of this type is known, for example, from DE 10 2011 014 165 A1. It is used in particular as part of a bridge circuit in a converter, by means of which an alternating voltage is converted into a direct voltage or vice versa, a direct voltage is converted into an alternating voltage. Current controller circuits are used for a wide variety of purposes. When operated within their design range (rated load), they often have a high efficiency of well over 90%, sometimes even over 96%. However, the efficiency often drops drastically at lower loads (partial load operation), sometimes to well below 90%, for example to around 86% at a load of only 10% of the rated load. The reason for the reduced efficiency is that the switching losses are largely independent of the switched current.

[0012] The problem of a current controller circuit only being operated at partial load arises in many applications. For example, a motor vehicle is typically only operated with a significant load when accelerating and possibly when driving uphill, while traveling at a constant speed requires considerably less power. A similar situation can be found, for example, with a storage and retrieval machine, which also requires considerable power during acceleration and deceleration, but only requires significantly less power when traveling at a constant speed.

[0013] It is known in the art to use a field-effect transistor or an IGBT as a switching element and to reduce the gate voltage during partial load operation. Purely as an example, reference can be made to US 2012 / 0 194 119 A1. This procedure is used, for example, with SiC- and Si-based switching elements. By reducing the gate voltage, it is possible to switch the switching element more quickly during partial load operation. Switching from the on to the off state and vice versa therefore takes less time, so that switching losses are reduced. At nominal load and also under overload, however, the switching element is switched more slowly to prevent inadmissible voltage overshoots. This procedure is not possible with a GaN-based switching element or with a low-voltage switch, since this could cause parasitic switching.Such switching elements are therefore always switched at their normal switching voltage (typically +5 V and 0 V). The power loss during partial load operation is acceptable.

[0014] The losses in partial load operation are already reduced by the current controller circuit known from DE 10 2011 014 165 Al.

[0015] The object of the present invention is to further develop a current controller circuit of the type mentioned at the outset in such a way that a possible parasitic switching on of the corresponding switching element when transferring the respective switch from the switched-on to the blocked state is reliably prevented.

[0016] The object is achieved by a current controller circuit having the features of claim 1. Advantageous embodiments of the current controller circuit are the subject of dependent claims 2 to 12.

[0017] According to the invention, the respective switch is transferred from the switched-on state to the blocked state only when the switching elements are in a blocked state due to the control signal output by the driver circuit.

[0018] The same procedure is preferably used to transfer the respective switch from the locked to the switched state. However, this is not critical.

[0019] There are therefore several switching elements that are connected in parallel and can be switched via a single output of the driver circuit. However, thanks to the switches in at least some of the connecting lines, individual switching elements can be switched off, so that they are no longer switched on regardless of the control signal output via the driver circuit output. This makes it possible to control all switching elements at nominal load and in the event of an overload, and to deactivate individual switching elements at partial load, so that the non-controlled switching elements are permanently blocked and the current is only conducted via the remaining switching elements.

[0020] Although the current controller circuit and its operation cannot reduce charge transfer losses, the turn-on losses and the gate charge transfer losses can be reduced.

[0021] It is possible for the connecting lines, starting from the control terminal of the respective switching element, to be led individually (i.e. individually and thus ultimately in parallel) directly to the output of the driver circuit. As a rule, however, the connecting lines are connected to one another at a node so that the connecting lines between the node and the output of the driver circuit are designed as a common, uniform connecting line. In this case, the switches are arranged in the respective (individual) connecting line between the node and the respective control terminal. If the driver current supplied by the output is set by means of a resistor, this resistor is preferably arranged between the node and the output of the driver circuit.

[0022] This design does have the consequence that when the current controller circuit is operated with a high load (nominal load and overload), the switching elements are switched relatively slowly. However, this is acceptable at nominal load and overload because nominal load operation and overload operation often only occur for a short time and, moreover, switching losses are not dominant in these operating modes. However, this design also has the consequence that when the current controller circuit is operated with a low load (partial load operation) and the respective switch is therefore switched to the blocked state, the driver current supplied by the output is only fed to the control connections of the remaining switching elements, so that these switching elements can be switched more quickly in partial load operation.

[0023] It is possible for a target current to be switched by means of the current controller circuit to be supplied to the control circuit. In this case, the control circuit can decide based on the target current whether to switch at least one of the switches to the blocked state or whether to keep all switches in the switched state. When converting an alternating voltage to a direct voltage or vice versa, the target current is usually not the current value varying over one period of the alternating voltage, but rather the effective value averaged over the period. Varying over the period of the alternating voltage is also possible, however.

[0024] Alternatively, it is possible for the control circuit to be supplied with an actual current switched by the current regulator circuit. In this case, the control circuit can decide, based on the actual current, whether to switch at least one of the switches to the blocked state or whether to keep all switches in the on state. When converting an alternating voltage to a direct voltage or vice versa, the actual current is usually not the effective value averaged over the period, but rather the current value varying over one period of the alternating voltage.

[0025] The latter approach offers the particular advantage that even in the case of high load requirements during phases in which only a small current needs to be switched temporarily, it is possible to open at least one of the switches temporarily.

[0026] Preferably, a switch is arranged in each of the connecting lines (in particular in all connecting lines), and the control circuit generates a separate additional signal for each switch. In this case, the control circuit can decide which of the switches it will switch to the blocked state and which of the switches it will switch to the switched state. Dynamic operation is therefore possible. In particular, the control circuit can specifically decide which of the switching elements should be used for the load current and which should not.

[0027] For example, it is possible for the control circuit (in partial load operation) to cyclically vary the switches that it switches into the blocked state. This evens out the thermal load on the switching elements. Alternatively, it is possible for the control circuit to know the respective temperature level of each switching element. In this case, the control circuit can (in partial load operation) switch those switches whose switching elements have the highest temperature level into the blocked state. In this case, the control circuit can specifically relieve the switching elements subject to the highest thermal load. The other switches, i.e. those not switched into the blocked state, are in the switched-on state.

[0028] Preferably, at least in those switching elements in which a respective switch is arranged in the respective connecting line to the output of the driver circuit, the respective control terminal and the respective second load terminal are connected to one another via a respective protective circuit. This allows the corresponding control terminals to be protected from impermissible voltages relative to the respective load terminals.

[0029] In the simplest case, the respective protective circuit is an uncontrolled protective circuit. In this case, the respective control terminal and the respective second load terminal are connected to one another with low impedance via the respective protective circuit if a potential of the respective control terminal exceeds a potential of the respective second load terminal by more than a predetermined limit voltage or is below the potential of the respective second load terminal. If, on the other hand, the potential of the respective control terminal exceeds the potential of the respective second load terminal but by less than the predetermined limit voltage, the respective control terminal and the respective second load terminal are connected to one another with high impedance via the respective protective circuit. This reliably protects the respective control terminal. In the simplest case, the respective protective circuit can be designed as a Zener diode.

[0030] Alternatively, the respective protective circuit can be designed as a controlled protective circuit. In this case, the protective circuit is designed as a respective additional switch that is controlled by the control circuit. The control can, in particular, be controlled inversely to the respective switch arranged in the respective connecting line.

[0031] The switching elements can be configured as required. Preferably, the switching elements are configured as voltage-controlled switching elements, in particular as IGBTs or FETs. Alternatively or additionally, the switching elements can be configured as low-voltage switches (switched voltage maximum 100 V, often maximum 50 V, in particular 10 V to 30 V) and / or as GaN semiconductors. However, other configurations of the switching elements are also possible.

[0032] The switches can also be designed as required. Preferably, the switches are designed as low-voltage switches (defined as above) with an integrated driver and / or as GaN semiconductors. However, other switch designs are also possible.

[0033] The above-described properties, features, and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more readily understood in connection with the following description of the embodiments, which are explained in more detail in conjunction with the drawings. Herein, in schematic representation:

[0034] FIG 1 a current controller circuit,

[0035] FIG 2 to 5 timing diagrams,

[0036] FIG 6 to 8 Modifications of the current controller circuit of

[0037] FIG 1 ,

[0038] FIG 9 a timing diagram and

[0039] FIG 10 a flow chart .

[0040] According to FIG. 1, a current controller circuit comprises a plurality of switching elements 1, 2. FIG. 1 shows a minimal configuration in which only two switching elements 1, 2 are present. This configuration is entirely sufficient for the vast majority of applications. However, more than two switching elements 1, 2 could also be present.

[0041] The structure of the switching element 1 is explained in more detail below. According to FIG 1, the switching element 1 has a first load connection 3 and a second load connection 4. The first load connection 3 is connected to a load input 5 of the current controller circuit, the second load connection 4 to a load output 6 of the current controller circuit. The switching element 1 also has a control connection 7. Furthermore, a diode 8 is usually connected in parallel with the switching element 1. The diode 8 can be an intrinsic diode of the switching element 1. Alternatively, it can be a separate component. The switching element 1 can be designed as a voltage-controlled switching element as shown in FIG 1. Specifically, the switching element 1 in FIG 1 is designed as an FET. However, it could also be designed differently, for example as an IGBT.

[0042] The switching element 2 is generally constructed in the same way as the switching element 1. Analogous designs therefore apply to the switching element 2. In particular, the load terminals 3, 4 of the switching element 2 are also connected to the load input 5 and the load output 6. As a result, the first load terminals 3 of the switching elements 1, 2 are connected to one another, and the second load terminals 4 of the switching elements 1, 2 are also connected to one another.

[0043] In many cases, a relatively high voltage is switched by means of the switching elements 1, 2, often even a voltage above 1 kV, in extreme cases up to 3 kV or even 3.3 kV. The switching elements 1, 2 can, however, also be designed as low-voltage switches that only switch a voltage of 100 V or less. In terms of their technology, the switching elements 1, 2 can, in principle, be designed in any desired manner. However, it is particularly advantageous if the switching elements 1, 2 are designed as GaN semiconductors.

[0044] The control connections 7 of the switching elements 1, 2 are connected to an output 10 of a driver circuit 11 by means of a respective connecting line 9. The output 10 is a common output for the control connections 7. A control signal C, which is output by the driver circuit 11 via the output 10, can therefore be fed to both control connections 7. However, a switch 12 is arranged in one of the connecting lines 9, here the connecting line 9 to the control connection 7 of the switching element 2. The switch 12 is preferably designed as a low-voltage switch with an integrated driver. With regard to its technology, the switch 12 can in principle be designed in any desired way. However, a design as a GaN semiconductor is particularly advantageous.

[0045] The current controller circuit further comprises a control circuit 13. The control circuit 13 generates a respective additional signal Z. The additional signal Z is fed to the switch 12. The additional signal Z is binary. Depending on the value of the additional signal Z, the switch 12 is either in a through-connected or in a blocked state. When the switch 12 is in the through-connected state, the control signal C is fed to the control terminals 7 of both switching elements 1, 2. If, on the other hand, the switch 12 is in the blocked state, the control signal C is only fed to the control terminal 7 of the switching element 1. The control signal C is also binary. Depending on the value of the control signal C, the switching elements 1, 2 to which the control signal C is fed are either in a through-connected or in a blocked state.

[0046] Often, as shown in FIG. 1, the connecting lines 9 are interconnected at a node 14. In this case, the switch 12 is arranged in the connecting line 9 between the node 14 and the control terminal 7 of the switching element 2. Furthermore, a resistor 15 is generally arranged between the node 14 and the output 10 of the driver circuit 11.

[0047] The functionality and operation of the current controller circuit are explained below in conjunction with FIGS. 2 to 5.

[0048] FIG 2 shows the current I (I current I ) switched by the current control circuit as a function of time t . Since the switched voltage (not shown) can be regarded as essentially constant, the current I is characteristic of the power switched via the current control circuit. According to FIG 2, the current I varies over time. In particular, the current I exceeds a threshold value 10 between times t1 and t2 and from a time t3 onwards, whereas before time t1 and between times t2 and t3 it lies below the threshold value 10 .

[0049] To adjust the current I, the driver circuit 11 generates the control signal C, which changes its signal level at a relatively high frequency according to FIG 3. A high signal level corresponds to the switching elements 1, 2 or at least one of the switching elements 1, 2 being switched on, so that the corresponding load connections 3, 4 are connected to one another with low resistance. A current flow is therefore possible. A low signal level corresponds to the switching elements 1, 2 being switched off, so that the load connections 3, 4 of the switching elements 1, 2 are connected to one another with high resistance. A current flow is suppressed.

[0050] If the (signed) actual current I is above the threshold value 10, the additional signal Z has a high signal level according to FIG 4, otherwise a low signal level. At a high signal level, the switch 12 is switched on, and at a low signal level it is blocked. Consequently, the control signal C (i.e. the signal emitted by the driver circuit 11 via the output 10) is fed to the control terminal 7 of the switching element 2 according to FIG 5 between times t1 and t2 and from time t3, but not before time t1 and between times t2 and t3. In contrast, the control signal C is always fed to the control terminal 7 of the switching element 1.

[0051] The crucial design of the operation of the current controller circuit is particularly evident from FIGS. 4 and 5. In particular, FIGS. 4 and 5 show that the transition of switch 12 from the switched-on state to the blocked state (and preferably also from the blocked state to the switched-on state) only occurs when switching elements 1, 2 are in a blocked state due to control signal C (control signal C is at a low level). If necessary, the switching of additional signal Z is slightly delayed so that the aforementioned condition is met.

[0052] The above explanations are correct in principle, but have been somewhat simplified for the sake of clarity.

[0053] Firstly, switching often occurs with a certain hysteresis. Threshold 10 is therefore divided into an upper threshold and a lower threshold. Switching element 2 is only activated when the upper threshold is exceeded. Likewise, switching element 2 is only deactivated when the lower threshold is undershot.

[0054] Secondly, within the current control circuit shown in FIG 1, when switching elements 1, 2 are blocked, no current I flows. For the purposes of evaluation by the control circuit 13, for example, the current I flowing during the immediately preceding switching of switching element 1 or of switching elements 1 and 2 can be utilized. It is also possible for an inductance to be arranged upstream or downstream of the current control circuit and for a current flow to be maintained (briefly) even when switching elements 1, 2 are blocked. In this case, this value of the current I can be used.

[0055] A procedure was explained above in which the actual current I switched by means of the current controller circuit (or a corresponding measured value) is fed to the control circuit 13. In this case, the control circuit 13 decides on the basis of the actual current I whether to switch the switch 12 into the blocked state or whether to keep the switch 12 in the switched state. Alternatively, it is possible, as indicated in parentheses in FIG 1, to feed the control circuit 13 a target current I * to be switched by means of the current controller circuit (or a corresponding target value). In this case, the control circuit 13 can make the same decision on the basis of the target current I *.

[0056] In the minimal configuration explained above, there is only a single switch 12 which can be switched into the blocked or switched-on state by the control circuit 13. It is also possible to provide a corresponding switch for the switching element 1. Even if more than two switching elements 1, 2 are present, more than one switch 12 can be present. In such cases, the control circuit 13 can decide - possibly in several stages - whether and, if so, which of the switches 12 it switches into the blocked state. The current controller circuits in FIGS. 6 and 7 are based on the current controller circuit in FIG. 1. Therefore, only the additions and modifications are explained below.

[0057] According to FIGS. 6 and 7, a protective circuit 16 is provided. The control terminal 7 and the second load terminal 4 of the switching element 2 are connected to each other via the protective circuit 16. The protective circuit 16 prevents overvoltages that could damage the switching element 2.

[0058] In the embodiment shown in FIG. 6, the protective circuit 16 is an uncontrolled protective circuit. It operates as follows, with all statements referring to the switching element 2:

[0059] - If a potential of the control terminal 7 is below a potential of the second load terminal 4, the control terminal 7 and the second load terminal 4 are connected to one another with low resistance via the protective circuit 16.

[0060] - If the potential of the control terminal 7 is higher than the potential of the second load terminal 4, the control terminal 7 and the second load terminal 4 are initially connected to one another with high resistance via the protective circuit 16.

[0061] - However, if the potential of the control terminal 7 exceeds the potential of the second load terminal 4 by more than a predetermined limit voltage, the control terminal 7 of the switching element 2 and the second load terminal 4 of the switching element 2 are connected to one another with low resistance via the protective circuit 16.

[0062] In the simplest case, the uncontrolled protection circuit is designed as a Zener diode as shown in FIG 6, the Zener voltage of which is the predetermined limit voltage.

[0063] In the embodiment according to FIG. 7, the protective circuit 16 is a controlled protective circuit. In this case, the protective circuit 16 is designed as an additional switch 17. The additional switch 17 is controlled by the control circuit 13. The control can, in particular, be inverse to the switch 12.

[0064] If more than two switches 12 are present, the embodiments of FIGS. 6 and 7 can be realized for each switching element 1, 2, whose control terminal 7 can be separated from the output 10 of the driver circuit 11 via a corresponding switch 12.

[0065] A further modification of the current controller circuit is explained below in conjunction with FIG. 8. This modification is explained based on the current controller circuit of FIG. 1. However, it can also be combined with the modification of FIG. 6 or the modification of FIG. 7, if required.

[0066] According to FIG. 8, a switch 12', 12" is arranged in each of the connecting lines 9. The switches 12', 12" have the same function as the switch 12 of FIG. 1. The reference numerals 12 and 12' are used only to make it easier to distinguish the two switches 12', 12" of FIG. 8 from one another.

[0067] According to FIG. 8, the control circuit 13 generates a separate additional signal Z', Z" for each of the switches 12', 12". The additional signals Z', Z" also have the same function as the additional signal Z of FIG. 1. The reference symbols Z' and Z" are used only to make it easier to distinguish between the two additional signals Z', Z" of FIG. 8.

[0068] In the case of the embodiment according to FIG 8, the control circuit 13 can, in the event that it wants to transfer one of the switches 12', 12" to the blocked state, decide which of the switches 12', 12" it will transfer to the blocked state and which it will transfer to the switched-on state or keep in the switched-on state. There are various possible procedures for this. In the simplest case, according to the illustration in FIG 9, it is possible for the control circuit 13 to cyclically vary the switches 12', 12" that it transfers to the blocked state. According to FIG 9, for example, one of the switches 12', 12" should be blocked whenever the actual current I (or alternatively the target current I*) falls below the threshold value 10 (partial load phases). These phases correspond to the periods in which the lowest signal of FIG 9, which is not provided with a reference symbol, has a low level.As can be seen from FIG 9, during the first partial load phase the additional signal Z' initially has a low level, so that the switch 12' is blocked. The additional signal Z", on the other hand, has a high level, so that the switch 12" is switched on. During the second partial load phase it is the other way round, so that the switch 12' is switched on, while the switch 12" is blocked. During the third partial load phase the switch 12' is again blocked, while the switch 12" is switched on. During the fourth partial load phase the switch 12' is again switched on, while the switch 12" is blocked. During the full load phases, however, when the actual current I (or alternatively the target current I*) is above the threshold value 10, both switches 12', 12" are switched on.

[0069] Alternatively, it is possible (see again FIG. 8) for the control circuit 13 to know a respective temperature level TI, T2 of the respective switching element 1, 2. This can be, for example, a junction temperature of the respective switching element 1, 2 or a temperature of a heat sink (not shown) that is thermally coupled to the respective switching element 1, 2. It can alternatively be a measured temperature or a temperature determined using a model. In such cases, the control circuit 13 can transfer those of the switches 12', 12" whose switching elements 1, 2 have the highest temperature level TI, T2 to the blocked state. A possible embodiment of this procedure is explained below in conjunction with FIG. 10.

[0070] According to FIG 10, the temperature levels TI, T2 are made known to the control circuit 13 in a step S1. In a step S2, the control device 13 checks whether a partial load phase is present, i.e., whether one of the switches 12', 12" should be blocked. If this is not the case, the control device 13 switches both the switch 12' and the switch 12" on in a step S3. The control signal C is therefore supplied to both switching elements 1, 2. The control device 13 then returns to step S1. If, however, a partial load phase is present, the control device 13 proceeds to a step S4. In step S4, the control device 13 checks whether the temperature level TI is above the temperature level T2. If this is the case, the control device 13 blocks the switch 12' in a step S5. Otherwise, the control device 13 blocks the switch 12" in a step S6.From both step S5 and step S6, the control device returns to step S1.

[0071] In summary, the present invention relates to the following:

[0072] A current controller circuit has a plurality of switching elements 1, 2, each having a first and a second load terminal 3, 4 and a control terminal 7. The first load terminals 3 are connected to one another. The second load terminals 4 are also connected to one another. The control terminals 7 are connected by means of a respective connecting line 9 to an output 10 of a driver circuit 11 that is common to the control terminals 7. A switch 12, 12', 12" is arranged in at least one of the connecting lines 9, so that a control signal C output by the driver circuit 11 via the output 10 is fed to the corresponding control terminal 7 or not, depending on whether the respective switch 12, 12', 12" is in a conductive or blocked state.The current regulator circuit has a control circuit 13, which generates a respective additional signal Z, Z', Z", which is fed to the respective switch 12, 12', 12", and on the basis of which the respective switch 12, 12', 12" is switched into the on or off state. The respective switch 12, 12', 12" is switched from the on to the off state only when the switching elements 1, 2 are in a off state due to the control signal C output by the driver circuit 11.

[0073] The present invention offers many advantages. In particular, the current control circuit is simple and robust, and power loss during partial load operation is significantly reduced.

[0074] Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited by the disclosed examples and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

Claims

Patent claims 1. Current regulator circuit, - wherein the current controller circuit comprises a plurality of switching elements (1, 2), each having a first and a second load terminal (3, 4) and a control terminal (7), - wherein the first load terminals (3) are connected to each other and the second load terminals (4) are connected to each other, - wherein the control terminals (7) are connected by means of a respective connecting line (9) to a (7) common output (10) of a driver circuit (11), - wherein a switch (12, 12', 12") is arranged in at least one of the connecting lines (9), so that a control signal (C) output by the driver circuit (11) via the output (10) is supplied to the corresponding control terminal (7) or not, depending on whether the respective switch (12, 12', 12") is in a switched-on or a blocked state, and - wherein the current controller circuit has a control circuit (13) which generates a respective additional signal (Z, Z', Z") which is fed to the respective switch (12, 12', 12") and on the basis of which the respective switch (12, 12', 12") is switched into the switched-on or the switched-off state, characterized in that the respective switch (12, 12', 12") is switched from the switched-on to the switched-off state only when the switching elements (1, 2) are in a switched-off state on the basis of the control signal (C) output by the driver circuit (11).

2. Current regulator circuit according to claim 1, characterized in that the connecting lines (9) are connected to one another at a node (14), that the switches (12, 12', 12") are arranged in the respective connecting line (9) between the node point (14) and the respective control connection (7) and that a resistor (15) is arranged between the node point (14) and the output (10) of the driver circuit (11).

3. Current controller circuit according to claim 1 or 2, characterized in that a target current (I*) to be switched by means of the current controller circuit or an actual current (I) switched by means of the current controller circuit is supplied to the control circuit (13), and in that the control circuit decides on the basis of the target current (I*) or the actual current (I) whether it switches at least one of the switches (12, 12', 12") to the blocked state or whether it keeps all the switches (12, 12', 12") in the switched-on state. 4 Current regulator circuit according to claim 1, 2 or 3, characterized in that a switch (12', 12") is arranged in each of the connecting lines (9), that the control circuit (13) generates a separate additional signal (Z', Z") for each of the switches (12', 12") and that the control circuit (13) decides which of the switches (12', 12") it transfers to the blocked state and which of the switches (12', 12") it transfers to the switched-on state.

5. Current regulator circuit according to claim 4, characterized in that the control circuit (13) cyclically varies the switches (12', 12") which it transfers to the blocked state.

6. Current regulator circuit according to claim 4, characterized in that the control circuit (13) knows a respective temperature level (TI, T2) of the respective switching element (1, 2) and that the control circuit (13) controls those of the switches (12', 12") are transferred to the blocked state, whose switching elements (1, 2) have the highest temperature level (TI, T2).

7. Current controller circuit according to one of the above claims, characterized in that at least in those of the switching elements (1, 2) in which a respective switch (12, 12', 12") is arranged in the respective connecting line (9) with the output (10) of the driver circuit (11), the respective control terminal (7) and the respective second load terminal (4) are connected to one another via a respective protective circuit (16).

8. Current controller circuit according to claim 7, characterized in that the respective protective circuit (16) is an uncontrolled protective circuit, in that the respective control terminal (7) and respective second load terminal (4) are connected to one another with low resistance via the respective protective circuit (16) when a potential of the respective control terminal (7) exceeds a potential of the respective second load terminal (4) by more than a predetermined limit voltage or is below the potential of the respective second load terminal (4), and in that the respective control terminal (7) and respective second load terminal (4) are connected to one another with high resistance via the respective protective circuit (16) when the potential of the respective control terminal (7) exceeds the potential of the respective second load terminal (4) but exceeds it by less than the predetermined limit voltage.

9. Current controller circuit according to claim 7, characterized in that the respective protective circuit (16) is designed as a respective further switch (17) and that the respective further switch (17) is controlled by the control circuit (13), in particular inversely to the respective switch (12) arranged in the respective connecting line (9).

10. Current controller circuit according to one of the above claims, characterized in that the switching elements (1, 2) are designed as voltage-controlled switching elements, in particular as IGBTs or as FETs.

11. Current controller circuit according to one of the above claims, characterized in that the switching elements (1, 2) are designed as low-voltage switches and / or as GaN semiconductors.

12. Current regulator circuit according to one of the above claims, characterized in that the respective switch (12, 12', 12") is designed as a low-voltage switch with integrated driver and / or as a GaN semiconductor.

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