SAFE ELECTRONIC SWITCH

Abstract

An electronic switch has a first, a second and a third connection and is configured to disconnect a current flow between the first and the second connection. An energy source is connected between the first and the third connection, and a regenerative load is connected between the second and the third connection. The electronic switch includes a semiconductor switch capable of switching currents of different polarity. A fuse is connected between the first connection and the semiconductor switch. A first short-circuiter is connected between the input of the semiconductor switch and the third connection, and a second short-circuiter is connected between the output of the semiconductor switch and the third connection. The fuse has a current trigger threshold between a permanently permitted current and a maximally permitted current of the semiconductor switch. An electrical network having such electronic switch and a method for operating an electronic switch are disclosed.

Claims

1.-9. (canceled)

10. An electrical network, comprising: an energy source and a regenerative road, an electronic switch having a first connection, a second connection and a third connection, with the energy source connected to the first connection and the third connection and the load connected to the second connection and the third connection, wherein the electronic switch is configured to disconnect a current flow between the first connection and the second connection, a semiconductor switch comprising two semiconductors, which can each switch off a current of different polarity, a first fuse connected between the first connection and an input of the semiconductor switch, a first short-circuiter connected between the input of the semiconductor switch and the third connection, and a second short-circuiter connected between the output of the semiconductor switch and the third connection.

11. The electrical network of claim 10, wherein at least one of the first and second short-circuiters is embodied as a thyristor.

12. The electrical network of claim 10, further comprising a second fuse connected between the output of the semiconductor switch and the second connection.

13. A method for operating en electronic switch of an electrical network, wherein the electronic switch has a first connection, a second connection and a third connection, with an energy source connected to the first connection and the third connection and a load connected to the second connection and the third connection, wherein the electronic switch is configured to disconnect a current flow between the first connection and the second connection, the electronic switch comprising a semiconductor switch comprising two semiconductors, which can each switch off a current of different polarity, a first fuse connected between the first connection and an input of the semiconductor switch, a first short-circuiter connected between the input of the semiconductor switch and the third connection, and a second short-circuiter connected between the output of the semiconductor switch and the third connection, the method comprising closing the first short-circuiter at least temporarily when the semiconductor switch is overloaded, and closing the second short-circuiter at least temporarily when the first short-circuiter is being closed or is closed.

14. The method of claim 13, further comprising closing the second short-circuiter when the first short-circuiter is closed and a current or a magnitude of the current through the semiconductor switch exceeds a predetermined limit value.

15. The method of claim 13, wherein the second short-circuiter is closed concurrently with the first short-circuiter.

Description

[0028] The invention will be described and explained below in greater detail with the aid of the exemplary embodiments shown in the figures. In the figures:

[0029] FIG. 1 and FIG. 2 show exemplary embodiments of an electronic switch,

[0030] FIG. 3 shows an exemplary embodiment of a short-circuiter,

[0031] FIG. 4 shows an electrical network, and

[0032] FIG. 5 and FIG. 6 shows time curves of variables of the semiconductor switch

[0033] FIG. 1 shows an electronic switch 1. The electronic switch 1 has a first connection 11, a second connection 12 and a third connection 13. A series circuit of a fuse 3 and a semiconductor switch 2 is arranged between the first connection 11 and the second connection 12. The semiconductor switch 2 has two semiconductors, which can each switch off a current of different polarity. Thus the electronic switch 1 is capable of switching a current i.sub.HL through the semiconductor switch 2 independently of its polarity, in particular to switch it off. A series circuit of the fuse 3 and a short-circuiter 4 is arranged between the first connection 11 and the third connection 13. In this case the components fuse 3, semiconductor switch 2 and short-circuiter 4 form a star circuit. In this star circuit these three components are connected to one another in a star point and furthermore are each connected to a connection of the electronic switch 1. The first connection 11 and the third connection 13 are provided for the connection with an energy source 7 not shown here or with an enemy-supplying DC bus. The second connection 12, or the voltage between the second connection 12 and third connection 13 is intended for connection to a load or a consumer. It is likewise possible to connect these connections to a subnetwork, which has a plurality of loads or electrical consumers.

[0034] FIG. 2 shows a further exemplary embodiment of an electronic switch 1 To avoid repetitions the reader is referred to the description for FIG. 1 as well as to the reference numbers quoted there. This electronic switch 1 has a further short-circuiter 41, which is arranged between the second connection 12 and the third connection 13 of the electronic switch 1. Thus the further short-circuiter 41 is arranged in parallel to a series circuit consisting of semiconductor switch 2 and short-circuiter 4. For simple connection to a source, in particular to an energy source 7 not shown here, and a load, the electronic switch 1 possesses the source-side connections, i.e. the first connection 11 and the third connection 13 and the load-side connections, i.e. the second connection 12 and a further connection 14. Since the further connection 14 is permanently coupled to the potential of the third connection 13, this further connection 14 can also be referred to as the third connection 13. Likewise a further connection 14 for connection to a consumer or a load can also be present outside the electronic switch. A conducting connection to the third connection 13 merely has to be provided.

[0035] Furthermore this electronic switch optionally has a further fuse 31 between the semiconductor switch 2 and the second connection 12. With this fuse both the first connection 11 and also the second connection 12 can be safely electrically disconnected from the semiconductor switch 2, in that, in the event of an overload of the semiconductor switch, the short-circuiter 4 and also the further short-circuiter 41 are simultaneously closed.

[0036] The short-circuiter 4 and the further short-circuiter 41 are each shown in this exemplary embodiment as a thyristor. If it can be assumed that the potential of the first or second connection 11, 12 is always greater than or equal to the potential of the third terminal 13, a single thyristor is sufficient. If on the other hand the third connection can also assume a higher potential than the first connection 11 or the second connection 12, then advantageously two thyristors are used in each case, which are arranged antiparallel to one another, FIG. 3 shows such an arrangement.

[0037] An electronic switch 1 with a short-circuiter 4 and/or a further short-circuiter 41 in accordance with FIG. 3 makes it possible to use it in DC networks, in which the polarity of the DC voltage can change, and to use it in AC networks.

[0038] FIG. 4 shows an electrical network 10 with an energy source 7 and an electronic switch 1. The electronic switch 1 In this case has the previously described connections 11, 12, 13. The further connection 14 is arranged outside the electronic switch 1 in this case and is connected to the third connection 13 of the electronic switch 1. The second connection 12 and the further connection 14 form the load-side connections for connection to one or more consumers or loads or to a subnetwork.

[0039] FIG. 5 shows the timing curve of the temperature T of the semiconductor switch 2. This temperature can involve the junction temperature of the semiconductor for example, which is determined by means of a computer model from measured values such as for example a temperature value and/or a current. With the aid of the temperature, in particular the junction temperature, a criterion can be formed, with which an overload or the threat of an overload of the semiconductor switch 2 can be recognized.

[0040] In this example the temperature T fluctuates, for example as a function of the operating state and/or the load on the semiconductor switch 2. If the temperature T reaches a predeterminable limit value T.sub.Max, as at point in time t.sub.off,1, then the short-circuiter 4 closes in order to create a short-circuit current through the fuse 3 and cause the fuse 3 to trigger. When it triggers, the fuse 3 goes into the disconnection state After the triggering of the fuse 3 the temperature T falls as a result of the load, caused by the current flow, no longer being present.

[0041] FIG. 6 shows the timing curve of the amount of current im through the semiconductor switch 2. The triggering of the short-circuiter 4 also enables a recovery current of the load to flow through the semiconductor switch 2 and short-circuiter 4. Because of the short circuit the amount of this current i.sub.HL increases rapidly. When the limit value I.sub.G is reached, at point in time t.sub.off,2, the further short-circuiter 41 closes and the recovery current no longer flows through the semiconductor switch 2 but flows through the further short-circuiter 41.

[0042] In summary the invention relates to an electronic switch, having a first, a second and a third connection, a semiconductor switch, a fuse, a short-circuiter, wherein a series circuit of the fuse and the semiconductor switch is arranged between the first connection and the second connection and a series circuit of the fuse and the short-circuiter is arranged between the first connection and the third connection. In other words the invention relates to an electronic switch for disconnecting a current flow between a first and a second connection, having a third connection, a semiconductor switch, a fuse, a short-circuiter, wherein a series circuit of the fuse and the semiconductor switch is arranged between the first connection and the second connection and a series circuit of the fuse and the short-circuiter is arranged between the first connection and the third connection, wherein the fuse has a trigger threshold with a current limit value, wherein the current limit value has a value between a permanently permitted current of the semiconductor switch and a maximum permitted current of the semiconductor switch. The invention further relates to an electrical network with at least one such electronic switch and an energy source, wherein the energy source is connected to the first connection and the third connection of the electronic switch. The invention further relates to a method for operating such an electronic switch or such an electrical network wherein, when the semiconductor switch is overloaded, the short-circuiter is closed at least temporarily.