Circuit arrangement for switching a current

Abstract

A circuit arrangement (100) for switching a current, comprising a first switching element (110) and a second switching element (120). The first and second switching elements are connected in parallel. The first leads (116, 126) of the first and second switching elements are routed through a first ferrite core (130).

Description

The invention relates to a circuit arrangement for switching a current. The invention further relates to a system having a circuit arrangement for switching a current and to a drive train having a system.Prior ArtTo increase the performance or current-carrying capacity of switching arrangements, for example half bridges or inverters, for example for driving 3 phase loads, "B6 topologies with parallel-connected switches" (e.g. FETs, IGBTs,... ) are typically used. The parallel connection of the switches makes it possible to maintain the electrical or thermal load of an individual switch within its permissible limits of use. In this case, the same current should always flow in the individual parallel-connected switching elements in an ideal manner. Thus, the current of an individual switching element would be halved in a circuit arrangement with parallel-connected switching elements in comparison to an individual switching element. As a result, either the current carrying capacity of the circuit arrangement can be increased (ideally doubled) for the same type of switch, or smaller types of switches can be used which require less installation space. In reality, the exact switching-on and switching-off operation of the individual switching elements of two parallel-connected switching elements is not exactly the same, despite the same type of switch, because of the tolerances of the components. If, for example, a first switching element turns on slightly earlier than a second switching element, then the full current initially flows briefly via this first switching element before it is finally halved by the switching on of the second switching element. This unbalanced switching operation brings about a short-term doubling of the current in the corresponding switching element. Alternatively, it is also possible to dimension or select the individual switches within a switching arrangement such that a parallel connection can be dispensed with. For this purpose, individual switches with very large chip areas must then be used. This in turn leads to larger component housings, or requires special chip contacting or chip packaging. In a simple parallel connection of switching elements, uneven current loads of the individual switching elements can occur at the on-switching and off-switching times of the parallel-connected switching elements. This results in overcurrents at at least one of the switching elements. Consequently, the overall performance of a circuit arrangement which results as a product of the individual performance and the number of parallel-connected switching elements cannot be fully utilized, since these unbalanced load cases are taken into account in the design of the circuit arrangement. The unbalanced loads increase even further by a positive feedback effect. The increased power loss of a switching element leads to increased temperatures, which leads to a further reduction of the switch-on threshold in a switching element. Ultimately, these effects shorten the life of a single switching element. There is therefore a need to provide simple pragmatic possibilities for parallel connections of switches.Disclosure of the InventionA circuit arrangement for switching a current is provided, having a first switching element and a second switching element. The first switching element has, on the one hand, a first terminal and, on the other hand, a second terminal. The first switching element is connected to the first terminal via a first lead and is connected to the second terminal via a second lead. The second switching element has, on the one hand, a first terminal and, on the other hand, a second terminal. The second switching element is connected to the first terminal via a first lead and is connected to the second terminal via a second lead. The first terminals of the first and second switching elements are connected to each other. The second terminals of the first and second switching elements are connected to each other. The first supply lines of the first and of the second switching element are led through a first ferrite core.A parallel connection of two switching elements is thus provided, at least two of the parallel supply lines of which are led through a ferrite core.Advantageously, a circuit arrangement is provided in which the loads of the switching elements to be connected in parallel are reduced, since the differential currents in the feed lines, or the currents through the feed lines, are attenuated by the feed lines through the ferrite core.In one configuration, the first feed line of the first switching element is led from the first switching element through the first ferrite core from a first side of the first ferrite core to a second side of the first ferrite core to the first connection of the first switching element. The first feed line of the second switching element from the second switching element is led from the second side of the first ferrite core through the first ferrite core to the first side of the first ferrite core to the first connection of the second switching element.The first supply lines of the first and of the second switching element are led through the ferrite core in opposite or opposite directions.A ferrite core is provided for a circuit arrangement having a first and a second switching element. The two lines or first feed lines of the first and of the second switching element enter the ferrite core in a "crossed" manner, i.e. the line of, for example, the first switching element runs within the ferrite core from left to right and the line of the second switching element runs within the ferrite core from right to left. The two lines are then brought together to form a connection pole or are connected to one another at a connection pole. Due to this "crossed" line routing of both switching elements within the ferrite core, identical currents and thus symmetrical currents in the individual switching elements are not impaired by the ferrite core, since the H fields or magnetic fields of the first supply lines of both switching elements, which run through the ferrite core, exactly compensate one another. However, if unbalanced currents occur in the individual switching elements, for example because of unbalanced switching operations of the individual switching elements, the H fields of the first feed lines of the two switching elements, which run through the ferrite core, do not compensate one another. The effect of the ferrite core is thus achieved and the current difference in the first feed lines of the two switching elements is attenuated or reduced. The ferrite core thus brings about a "symmetrization" of the currents in the individual switching elements of a parallel connection of a first and a second switching element. In this way, temporary peak loads or overcurrents / overvoltage in the individual switching elements are advantageously reduced or eliminated.In one configuration, the second feed lines are guided through a second ferrite core.A parallel connection of two switching elements is thus provided, wherein their first parallel feed lines are guided through a first ferrite core and wherein their second parallel feed lines are guided through a second ferrite core.Advantageously, a circuit arrangement is provided in which the loads of the switching elements to be connected in parallel are reduced, since the differential currents in the feed lines, or the currents through the feed lines, are attenuated by the feed lines being passed through the first ferrite core and the second ferrite core.In one configuration, the second feed line of the first switching element is led from the first switching element through the second ferrite core from a first side of the second ferrite core to a second side of the second ferrite core to the second connection of the first switching element. The second feed line of the second switching element from the second switching element is led from the second side of the second ferrite core through the second ferrite core to the first side of the second ferrite core to the second connection of the second switching element.The second feed lines of the first and of the second switching element are led through the second ferrite core in opposite or opposite directions.According to the above description, temporary peak loads or overcurrents / overvoltage in the individual switching elements are advantageously reduced or eliminated in this way by means of the second ferrite core.In one configuration, the first or second ferrite core is configured as a ferrite sleeve, ferrite ring or differently shaped ferrite and is configured in such a way that a first or second feed line of one of the switching elements can be carried out.The configuration of the ferrite core is almost arbitrary as long as it is possible to pass through first or second feed lines of a first and a second switching element, so that the effect of the ferrite core for influencing the H fields or magnetic fields results. Alternatively, wired ferrite components, also in the SMD format, are also suitable, in particular for automated component mounting. Advantageously, different possibilities for configuring the ferrite core are provided.The invention further relates to a system comprising at least two described circuit arrangements, wherein the circuit arrangements are arranged as a series circuit to form a half bridge, or are connected in parallel, or are arranged as a full bridge or B6 bridge as a combination of series circuit and parallel circuit.Advantageously, possibilities of using and combining a plurality of circuit arrangements are provided, the temporary overcurrents of which are reduced by means of the ferrite cores.The invention further relates to a drive train having a described system. The drive train comprises at least one load, in particular an electric machine, connected on the one hand to the system, or an energy source, in particular a battery or high-voltage battery, connected on the other hand to the system.A drive train with a described system is advantageously provided. By using the switch arrangements, it is also possible to switch high currents preferably into traction drives or heat pumps, wherein temporary overcurrents are reduced by means of the ferrite cores.It is understood that the features, properties and advantages of the circuit arrangement correspondingly apply or are applicable to the system or the drive train and vice versa.Further features and advantages of embodiments of the invention will become apparent from the following description with reference to the attached drawings.BRIEF DESCRIPTION OF THE DRAWINGThe invention will be explained in more detail below with reference to some figures, in which: FIG. 1 shows a schematic illustration of a circuit arrangement having a first ferrite core, FIG. 2 shows a schematic illustration of a circuit arrangement having a first and a second ferrite core. FIG. 3 shows a further schematic illustration of a system comprising at least two circuit arrangements, FIG. 4 shows a further schematic illustration of a drive train with a system.Embodiments of the InventionFIG. 1 shows a circuit arrangement 100 for switching a current I, having a first switching element 110 and a second switching element 120. The first switching element 110 has, on the one hand, a first terminal 112 and, on the other hand, a second terminal 114, wherein the first switching element 110 is connected to the first terminal 112 via a first feed line 116, wherein the first switching element 110 is connected to the second terminal 114 via a second feed line 118. The second switching element 120 has, on the one hand, a first terminal 122 and, on the other hand, a second terminal 124. The second switching element 120 is connected to the first terminal 122 via a first lead 126, wherein the second switching element 120 is connected to the second terminal 124 via a second lead 128. The first terminals 112, 122 of the first and second switching elements are connected to one another and the second terminals 114, 124 of the first and second switching elements are connected to one another, resulting in a parallel connection of the first and second switching elements 110, 120. The first supply lines 116, 126 of the first and of the second switching element are led through a first ferrite core 130. Preferably, the first feed line 116 of the first switching element is led from the first switching element 110 from a first side 132 of the first ferrite core through the first ferrite core 130 to a second side 134 of the first ferrite core to the first connection 112 of the first switching element. Preferably, the first feed line 126 of the second switching element is led from the second switching element 120 from the second side 134 of the first ferrite core through the first ferrite core 130 to the first side 132 of the first ferrite core to the first connection 122 of the second switching element.FIG. 2 shows a further embodiment of the circuit arrangement 100, as is also shown in FIG. 1, with the difference that a second ferrite core 140 is preferably provided, wherein the second feed lines 118, 128 of the first and of the second switching element are led through the second ferrite core 140. Preferably, the second feed line 118 of the first switching element is led from the first switching element 110 from a first side 142 of the second ferrite core through the second ferrite core 140 to a second side 144 of the second ferrite core to the second connection 114 of the first switching element. The second feed line 128 of the second switching element is led from the second switching element 120 from the second side 144 of the second ferrite core through the second ferrite core 140 to the first side 142 of the second ferrite core to the second connection 124 of the second switching element. The remaining reference numerals correspond to those from FIG. 1.FIG. 3 shows a schematic illustration of a system 200 comprising at least two circuit arrangements 100 described. The circuit arrangements 100 are preferably arranged as a series circuit to form a half bridge 210. An arrangement as a parallel circuit is also possible or preferably a full bridge 220 as a combination of series circuit and parallel circuit, or a B6 bridge 250.FIG. 4 shows a schematic illustration of a drive train 300 with a described system 200. The drive train 300 has at least one load 310, in particular an electric machine, connected on the one hand to the system 200, or an energy source 320, in particular a battery or high-voltage battery, connected on the other hand to the system.

Claims

Circuit arrangement (100) for switching a current, having a first switching element (110) and a second switching element (120), characterized in that the first switching element (110) has, on the one hand, a first terminal (112) and, on the other hand, a second terminal (114), the first switching element (110) being connected to the first terminal (112) via a first feed line (116), the first switching element (110) being connected to the second terminal (114) via a second feed line (118), and the second switching element (120) having, on the one hand, a first terminal (122) and, on the other hand, a second terminal (124), the second switching element (120) being connected to the first terminal (122) via a first feed line (126), the second switching element (120) being connected to the second terminal (124) via a second feed line (128), the first terminals (112, 112, 122) of the first and the second switching element are connected to one another and the second terminals (114, 124) of the first and the second switching element are connected to one another, wherein the first feed lines (116, 126) of the first and the second switching element are led through a first ferrite core (130).The circuit arrangement according to claim 1, wherein the first lead (116) of the first switching element is led from the first switching element (110) through the first ferrite core (130) from a first side (132) of the first ferrite core to a second side (134) of the first ferrite core to the first terminal (112) of the first switching element, and the first lead (126) of the second switching element is led from the second switching element (120) through the first ferrite core (130) from the second side (134) of the first ferrite core to the first side (132) of the first ferrite core to the first terminal (122) of the second switching element.Circuit arrangement according to Claim 1 or 2, wherein the second feed lines (118, 128) of the first and of the second switching element are led through a second ferrite core (140).Circuit arrangement according to Claim 3, wherein the second lead (118) of the first switching element is led from the first switching element (110) through the second ferrite core (140) from a first side (142) of the second ferrite core to a second side (144) of the second ferrite core to the second terminal (114) of the first switching element, and the second lead (128) of the second switching element is led from the second switching element (120) through the second ferrite core (140) from the second side (144) of the second ferrite core to the first side (142) of the second ferrite core to the second terminal (124) of the second switching element.Circuit arrangement according to one of the preceding claims, wherein the first or second ferrite core (130, 140) is designed as a ferrite sleeve, ferrite ring or differently shaped ferrite which is designed such that a first or second feed line (116, 126, 118, 128) can be passed through.The system 200 of at least two circuit arrangements (100) according to one of the preceding claims, wherein the circuit arrangements (100) are arranged as a series circuit to a half bridge (210) or are connected in parallel or are arranged as a full bridge (220) or B6 bridge (250) as a combination of series circuit and parallel circuit.Drive train 300 with a system according to Claim 6, wherein the drive train comprises at least one load (310), in particular an electric machine, which is connected on the one hand to the system (200), or an energy source (320), in particular a battery or high-voltage battery, which is connected on the other hand to the system.

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