The invention relates to the field of signal transformer technology. It is based on a signal transformer and a method for operating such a signal transformer in accordance with the preamble of claims 1 and 20.
Signal transformers are nowadays used in a multiplicity of power electronic circuits, in particular in driver circuits for driving power semiconductor switches of converters. In this case, the signal transformer of the driver circuit serves for DC isolation of a signal function generator from the power semiconductor switch to be driven. Such a signal transformer is specified in GB 2 293 933 A, for example, wherein a first signal transformer is provided for DC-isolated transmission of a switch-on signal of the power semiconductor switch and a second signal transformer is provided for DC-isolated transmission of a switch-off signal of the power semiconductor switch. The two signal transformers are customarily embodied with two limbs in each case, the first limb being at least partly enclosed by a primary winding and the second limb being at least partially enclosed by a secondary winding. The two limbs of each such signal transformer are usually connected to one another in such a way that a magnetic circuit is produced, in which a main magnetic flux generated by the respective primary winding can flow.
What is problematic in the case of a signal transformer described above in accordance with GB 2 293 933 A is that this enables only a single primary winding signal present at the primary winding, for example a switch-on signal or a switch-off signal, to be transmitted as a secondary winding signal. However, if the intention is, for example, to provide two secondary winding signals, namely a switch-on signal and a switch-off signal, for example, as in the case of an abovementioned driver circuit for driving a power semiconductor switch, then a signal transformer with a respective signal function generator connected to the primary winding of the signal transformer has to be provided for each secondary winding signal. It is thus not possible to transmit a single primary winding signal on the transformer input side as a plurality of secondary winding signals on the transformer output side. By virtue of the fact that, therefore, only precisely one primary winding signal can be transmitted as a secondary winding signal in the case of a signal transformer described above in accordance with GB 2 293 933 A, when there are a plurality of secondary winding signals to be made available, as in the case of the driver circuit in accordance with GB 2 293 933 A, there is a huge increase in the material costs on account of the number of signal transformers required. A large number of signal transformers is additionally accompanied by an undesirably large space requirement. Furthermore, the availability of an abovementioned driver circuit decreases as the number of signal transformers rises, since the probability of faults increases with an increased number of signal transformers. Finally, this can result in long maintenance times associated with high maintenance costs which are unacceptable for an operator of, for example, a converter with driver circuits of this type.
Therefore, it is an object of the invention to specify a signal transformer in which a signal on the transformer input side can be transmitted as a plurality of output signals, which is furthermore particularly space-saving, is distinguished by a high availability and, moreover, is constructed simply, cost-effectively and in a readily maintainable fashion. Furthermore, the intention is to specify a method which enables particularly efficient operation of such a signal transformer. These objects are achieved by means of the features of claims 1 and 20. Advantageous developments of the invention are specified in the subclaims.
The signal transformer according to the invention has a primary limb and a first secondary limb, a primary winding being provided, which at least partly encloses the primary limb, and a secondary winding furthermore being provided, which at least partly encloses the first secondary limb. Moreover, the primary limb is connected to the first secondary limb. According to the invention, 2n+1 additional limbs are provided, where n=0, 1, 2, 3, . . . , and the additional secondary limbs are connected to the primary limb and the first secondary limb. At least one secondary winding is in each case provided for the additional secondary limbs and for the first secondary limb, the secondary winding at least partly enclosing the respective secondary limb. Furthermore, a control winding is provided for each secondary limb, said control winding at least partly enclosing the respective secondary limb. By virtue of the fact that 2n+1 additional secondary limbs, i.e. an odd number of additional secondary limbs, are provided and at least one secondary winding is in each case provided for the additional secondary limbs and for the first secondary limb, a primary winding signal fed into the primary winding can advantageously be transmitted to all the secondary windings so that a secondary winding signal is present at each output of the secondary windings. Transmission of a single primary winding signal as a plurality of secondary winding signals, i.e. as a number of secondary winding signals corresponding to the number of secondary windings, is thus made possible in a particularly simple manner. Accordingly, only a single signal transformer is required for transmitting a primary winding signal as a plurality of secondary winding signals, as a result of which a simple and cost-effective signal transformer requiring little space and materials can advantageously be achieved.
Moreover, by means of a control signal being fed into the control winding provided for each secondary limb, the secondary winding signal of the corresponding secondary limb can be switched on or off in a targeted manner, so that, by way of example, maintenance work can be carried out on this secondary limb without having to interrupt the operation of the signal transformer. As a result, it is advantageously possible to realize a signal transformer which is highly maintainable and characterized by a high availability.
In the invention's method for operating the signal transformer, a main flux is generated in the primary limb by feeding the primary winding signal into the primary winding. The main flux of the primary limb is furthermore divided into partial fluxes between the secondary limbs on both sides of the primary limb, the number of partial fluxes on one side of the primary limb corresponding to the number of secondary limbs on this side. Furthermore, according to the invention, the control signal is fed into at least one control winding in such a way that a control flux is generated in the associated secondary limb, the secondary winding signal present at the associated secondary winding of the corresponding secondary limb being influenced by means of the control flux. The influencing of the secondary winding signal is caused by the control flux, which influences, in particular reduces, compensates for or amplifies, the partial flux of the corresponding secondary limb. In the case of exemplary compensation of the partial flux by the generation of a control flux which counteracts the partial flux, no secondary winding signal is present at the associated secondary winding, so that said signal is switched off. The possibility of virtually arbitrary influencing of the corresponding secondary winding signal by the control flux enables the signal transformer to be operated particularly efficiently.
The signal transformer according to the invention is particularly advantageously employed in a driver circuit for at least one drivable power semiconductor switch. According to the invention, such a driver circuit has the signal transformer according to the invention, the driver circuit additionally comprising a signal function generator and the signal transformer according to the invention preferably being connected in between said signal function generator and the at least one drivable power semiconductor switch. Consequently, a multiplicity of the abovementioned drivable power semiconductor switches, which are advantageously in each case connected to a secondary winding of the signal transformer, can be driven by only a single signal transformer. Thus, the use of the signal transformer according to the invention in the driver circuit makes it possible to obtain a particularly space-saving, simple, cost-effective and readily maintainable driver circuit which is furthermore distinguished by a high availability.
This and further objects, advantages and features of the present invention will become apparent from the detailed description below of preferred embodiments of the invention in conjunction with the drawing.
In the figures:
The reference symbols used in the drawing and their meanings are summarized in the List of designations. In principle, identical parts are provided with identical reference symbols in the figures. The embodiment described is an example of the subject matter of the invention and has no restrictive effect.
By feeding a control signal Sst into the control winding 3 provided for each secondary limb 6 in accordance with
In accordance with
In accordance with
The above-described primary winding 2, secondary windings 6 and control windings 3 are in each case realized as wound conductors in accordance with
In a preferred first embodiment of the secondary winding 6, in particular for more than one secondary winding 6 per secondary limb 4, 5, and of the control winding 3 of the signal transformer according to the invention as shown in
In a second embodiment of a multilayer printed circuit board 12 in accordance with
In a third embodiment of a multilayer printed circuit board 12 in accordance with
It goes without saying that the signal transformer according to the invention is not restricted to realizations with the above-described combinations of the embodiments of the primary windings 2, secondary windings 6 and control windings 3, in particular according to
Overall, the signal transformer according to the invention represents a particularly space-saving, simple, cost-effective and readily maintainable solution which, moreover, has a high degree of availability.
In the invention's method for operating the signal transformer, a main flux ΦH is generated in the primary limb 1 by feeding the primary winding signal Sp into the primary winding 2. The main flux ΦH of the primary limb 1 is divided into partial fluxes ΦT1, ΦT2, ΦT3, . . . between the secondary limbs 4, 5 on both sides of the primary limb 1, the number of partial fluxes ΦT1, ΦT2, ΦT3, . . . on one side of the primary limb corresponding to the number of secondary limbs 4, 5 on this side. Each partial flux ΦT1, ΦT2, ΦT3, . . . in the associated secondary limb 4, 5 effects a secondary winding signal Ss in the secondary winding or windings 6 of the associated secondary limb 4, 5. According to the invention, the control signal Sst is fed into at least one control winding 3 in such a way that a control flux is generated in the associated secondary limb 4, 5. The secondary winding signal Ss present at the associated secondary winding 6 of the corresponding secondary limb 4, 5 is then influenced by the control flux. The influencing of the secondary winding signal Ss is caused by the control flux, which influences the partial flux ΦT1, ΦT2, ΦT3, . . . Of the corresponding secondary limb 4, 5, i.e. reduces, compensates for or amplifies the partial flux ΦT1, ΦT2, ΦT3, . . . of the corresponding secondary limb 4, 5. By way of example, if a control flux is generated which counteracts the corresponding partial flux ΦT1, ΦT2, ΦT3, . . . in such a way that the partial flux ΦT1, ΦT2, ΦT3, . . . is compensated for, then no secondary winding signal Ss is present at the associated secondary winding 6. The secondary winding signal Ss would then be switched off in this example. The possibility of the virtually arbitrary influencing of the corresponding secondary winding signal Ss by the control flux enables the signal transformer to be operated particularly efficiently.
Preferably, in the method according to the invention, the secondary winding signal Ss is switched on or off by the control flux. In this case, the secondary winding signal Ss is switched off in the manner described above. By contrast, the secondary winding signal Ss is switched on for example by virtue of the fact that no control signal Sst is applied to the corresponding control winding 3 and, consequently, no control flux which compensates for the corresponding partial flux ΦT1, ΦT2, ΦT3, . . . is generated.
The signal transformer according to the invention is particularly advantageously employed in a driver circuit for at least one drivable power semiconductor switch, in particular for a bipolar transistor having a driving electrode arranged in an insulated manner, turn-off thyristor, such as GTO or IGCT, for example, and/or for a power MOSFET. According to the invention, such a driver circuit has a signal transformer described above. The driver circuit furthermore comprises a signal function generator, the signal transformer according to the invention preferably being connected in between said signal function generator and the at least one drivable power semiconductor switch. By virtue of the fact that at least one secondary winding 6 is in each case provided for the additional secondary limbs 5 and for the first secondary limb 4 of the signal transformer, the primary winding signal Sp fed into the primary winding 1 can be transmitted to all the secondary windings 6. Consequently, a multiplicity of the abovementioned drivable power semiconductor switches, which are advantageously each connected to a secondary winding 6, can be supplied with the drive signals required for driving, which signals are the respective secondary winding signals Ss, by just a single signal transformer. Via the respective control windings 3 of the secondary limbs 4, 5, the corresponding secondary winding signals Ss can then be switched on or off by the method according to the invention described above, as a result of which a very simple functionality of the driver stage can be achieved.
If a plurality of drivable power semiconductor switches are to be switched on or off essentially simultaneously, as is customarily required with series circuits of power semiconductor switches, then the embodiment of the signal transformer according to the invention with a number of secondary windings 6 for each secondary limb 4, 5 corresponding to the number of power semiconductor switches to be switched on or off virtually simultaneously is advantageously to be used for a driver circuit. Each of these power semiconductor switches is then connected to one of the secondary windings 6 of the corresponding secondary limb 4, 5. By means of the control signal Sst mentioned in the method according to the invention described above, the secondary winding signals Ss can then advantageously be switched on or off for such a secondary limb 4, 5 in a targeted manner and virtually simultaneously in a manner required for this case.
Overall, the use of the signal transformer according to the invention in a driver circuit for at least one drivable power semiconductor switch makes it possible to realize a particularly space-saving, simple, cost-effective and readily maintainable driver circuit which, moreover, encompasses a high degree of availability.
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