DE4014302A1 - Variable DC supply for two pole appts. - has parallel sources with short circuit switches and series decoupling diodes allowing adjustment in stages - Google Patents

Abstract

The arrangement supplies a two-pole load (5) with a load-independent d.c. adjustable in stages. A group of switchable sources (6) is connected to the load. Each source contains a load-independent d.c. source (7) with a short circuit switch (8) which is closed when the source is switched off. Each source has a series decoupling diode (9). The source circuits, including diodes, are connected in parallel with the load. Each source has a fixed associated current value. The switches are switched on and off in a combination giving the closest match to the current to be applied to the load. USE/ADVANTAGE - Use of common current source types considerably reduces costs of development and implementation. Spark erosion, plasma-support chemical vapour deposition, excitation of solid state lasers or pulsed welding.

Description

In numerous applications of modern technology increasingly the task in the context of technical processes electrical consumer bipoles with dynamically impressed and yet supply quickly changeable direct current. Especially when it comes to material processing these consumer bipoles usually around discharge routes.

These are only examples of such technical processes material processing by means of spark erosion, the coating of materials with plasma-assisted CVD, dry etching of surfaces with low-pressure plasmas, the tungsten protective gas and gas-shielded metal welding and material processing called with the help of solid-state lasers.

The prior art is to be described using an example be, namely at a power source to supply the Blitzlam pen of an optically pumped solid-state laser.

Such a current source is usually designed as a potential-binding DC step-down converter ( 1 ) as shown in FIG. 1.

If in this arrangement the electronic switch ( 2 ), which is shown in FIG. 1 as a bipolar npn transistor, is switched through, the input voltage U₀ is applied to the series circuit from the two -pole ( 5 ) flash lamps and the storage inductor ( 4 ). The consequence of this is that a current i _L <0 flowing through the storage inductor ( 4 ) is "driven" by the voltage u _F = U₀. If the electronic switch ( 2 ) is blocked again after its switch-on interval, the current i _L <0 must continue to flow through the storage inductor ( 4 ). Accordingly, the freewheeling diode ( 3 ) now takes over this current and the voltage u _F across this diode assumes the value zero. The arithmetic mean value of the current flowing through the storage inductor ( 4 ) - and thus also through the consumer dipole ( 5 ) - current i _L = i _A is brought to the desired level in that the arithmetic mean value of the voltage u _F to that required Value is set. This takes place via the so-called relative switch-on duration of the electronic switch ( 2 ), ie via the ratio of the duration of its switch-on interval to the sum of the durations of its switch-on interval and its switch-off interval.

To a power source for one of the applications mentioned above is now very often the requirement that a jump change the setpoint for their output current sets to its new value as quickly as possible, e.g. B. a so-called called "pulsability" to enable this current. At the same time but mostly still required that the fluctuation range of the output current is as low as possible with a constant setpoint.

In the case of the potential-connecting DC step-down converter ( 1 ) shown in FIG. 1, the inductance of the storage inductor ( 4 ) is only very small in view of a rapid change in the current when there is a change in the setpoint value, so there is a small fluctuation range in the output current i _A can only be achieved with a correspondingly high switching frequency of the electronic switch ( 2 ). In view of the properties of the power electronic switching elements used, this switching frequency has significant upper limits both for economic and technical reasons.

If, on the other hand, the inductance of the storage choke ( 4 ) is dimensioned so large in the potential-connecting DC step-down converter shown in FIG. 1 that the desired, low fluctuation range of the output current can be maintained at switching frequencies of the electronic switch ( 2 ) that are still technically and economically viable, With this circuit arrangement, only modest current change speeds can be achieved which by no means meet the high requirements mentioned.

In the vast majority of the applications mentioned at the outset, however, a completely constant adjustability of the current through the consumer dipole ( 5 ) is not necessary at all. It is much more sufficient to pass the current through the consumer dipole ( 5 ) sufficiently fine, z. B. in 63 such levels. The present invention takes advantage of this fact.

Essential components of the device according to the invention are so-called switchable and switchable direct current sources ( 6 ). Such are constructed as shown in Fig. 2 such that a switch ( 8 ), hereinafter referred to as short-circuit switch, is arranged in parallel with an impressed direct current source ( 7 ), via which the current of the impressed direct current source ( 7 ) can flow if it is Short circuit switch ( 8 ) is closed. If the short-circuit switch ( 8 ) is open, the on and off switchable direct current source ( 6 ) is in its switched-on state, and it is in its switched-off state when the water short-circuit switch ( 8 ) is closed.

The first key concept of the present invention is to supply said consumer dipole ( 5 ) via a group of n (n integer and greater than 1) of such direct current sources ( 6 ) which can be switched on and off and which are of similar construction but can differ in the size of their current. In each case, a diode ( 9 ), hereinafter called a decoupling diode, is added to each of these direct current sources ( 6 ) that can be switched on and off, so that the individual direct current sources that can be switched on and off do not influence one another. The resulting Anordnun gene are connected in parallel to the consumer two pole ( 5 ) as shown in Fig. 3. The individual decoupling diodes ( 9 ) are each polarized so that the current of the associated switchable and switchable direct current source ( 6 ) can flow through the consumer dipole ( 5 ) when this switchable and switchable direct current source is in its switched on state. Each of the n switched-on and switched-off direct current sources ( 6 ) thus connected has a fixed value of the current impressed in its direct current source ( 7 ) that is uniquely assigned to the relevant switched on and off switchable direct current source.

The second key concept of the invention is that the switching states of the n on and off switchable direct current sources ( 6 ) are each set so that the current flowing through the consumer pole ( 5 ), hereinafter referred to as current, best possible setpoint for this purpose comes close, namely as close as is feasible given the grading of the actual value of the consumer current given the arrangement described.

For further explanation, FIG. 3 is to be used again. In the idle state (if the consumer current i _A therefore has the value zero), all n direct current sources 6 which can be switched on and off are in their switched off state. If a sub-ensemble of the n switchable and deactivatable DC sources is then switched on by opening the short-circuit switch ( 8 ) of this sub-assembly, a total current i _A flows through the consumer branch terminal ( 5 ), which is the sum of the DC sources ( 7 ) in the now switched on and off direct current sources ( 6 ) results in impressed currents.

If a situation is subsequently brought about in which another part ensemble of the n switchable and switchable direct current sources 6 is switched on and the then remaining switchable and switchable direct current sources ( 6 ) are switched off, the current i _A through the consumer takes two pole ( 5 ) that value which results from the sum of the individual currents of the direct current sources ( 6 ) which can now be switched on and off.

The short circuit switch ( 8 ) can with the help of power electronic components such. B. bipolar transistors, MOS field effect transistors, IGBTs (insulated gate bipolar transistors) or FCDs (field-controlled diodes) can be realized. Such components usually require compliance with certain minimum intervals both for their switched on and for their switched off state. To meet these requirements, it is particularly advantageous if a change in the switching states of the n direct current sources ( 6 ) which can be switched on and off is carried out exclusively at uniform times which follow one another at equidistant intervals.

According to the illustration in FIG. 4, the status request ZW present for the respective DC source ( 6 ) that can be switched on and off is first routed to the input of a D flip-flop ( 10 ) and only with the rising edge of the for all n and switchable direct current sources ( 6 ) of uniform clock Φ at the output of this D flip-flop ( 10 ). Depending on the logic state at the output of the D flip-flop ( 10 ), the short-circuit switch ( 8 ), which is exemplified in FIG. 4 as a bipolar npn transistor, is then put into a conductive or a blocking state via a control circuit ( 11 ).

This procedure ensures, on the one hand, that a minimum switch-on interval of a full cycle period of the clock ein and an equally long minimum switch-off interval are always observed for the short-circuit switch 8 . On the other hand, overall there is a very high level of interference immunity because only largely calmed signals influence the decision about new switching operations, since the last switchover in the overall system was at least one full cycle period of the cycle Φ.

In one of its forms, the present invention provides, as shown in FIG. 5, that the direct current sources ( 7 ) of the n direct current sources that can be switched on and off ( 6 ) are each in the form of potential-connecting direct current step-down converters ( 12 ) are executed. The arithmetic mean of the output current of such a DC step-down converter ( 12 ) is adjusted to a fixed, constant value. The inductance of the storage choke ( 15 ) of this DC step-down converter ( 12 ) is dimensioned so large that the course of the output current from the DC step-down converter does not leave a pre-given tolerance band.

An example of a direct current source that can be switched on and off with such a direct current step-down converter ( 12 ) is shown in FIG. 5. There, the DC step-down converter ( 12 ) is supplied on the input side by the DC voltage source ( 13 ) with the voltage U).

The DC step-down converter ( 12 ) itself consists of the electronic switch ( 14 ), which is designed in Fig. 5 as an example as a bipolar npn transistor, from the Speicherdros sel ( 15 ) and from the free-wheeling diode ( 16 ), which is arranged in such a way is that a current flowing through the storage inductor ( 15 ) i _L <0 then flows through this freewheeling diode ( 16 ) when the electronic switch ( 14 ) is open. The principle of operation of such a DC step-down converter has already been explained in detail above.

The arrangement just described is supplemented by the short-circuit switch ( 8 ), which is parallel to its output, for switching the direct current source on and off.

If, after opening this short-circuit switch ( 8 ), the consumer two-pole ( 5 ) is not or not yet sufficiently conductive, the voltage at this consumer two-pole ( 5 ) and at the short-circuit switch ( 8 ) increases to such high values that either this short-circuit switch ( 8 ), which is usually designed as a semiconductor switch, is destroyed or that there are undesired external flashovers at the consumer branch terminal ( 5 ). Because of this problem, it is advisable to limit the voltage at the short-circuit switch ( 8 ) and thus also at the consumer dipole ( 5 ) to a value that is greater than the voltage required to ignite the consumer dipole ( 5 ) but less than that at the short-circuit switch ( 8 ) maximum permissible voltage and is also lower than that limit voltage at which there are harmful external arcing at the consumer branch terminal ( 5 ).

Such a limitation of the voltage at the short-circuit switch ( 8 ) can be carried out in its simplest form by a zener diode ( 17 ) which, as shown in FIG. 6, is placed in parallel with this short-circuit switch ( 8 ). It is polarized so that the current i _L through the storage inductor ( 15 ) only flows through the Zener diode ( 17 ) when the voltage at the short-circuit switch has risen above its breakdown voltage U _z . In this case, the Zener diode ( 17 ) limits the voltage at the short circuit switch to the value of its breakdown voltage U _z .

Since the resulting high losses in the Zener diode ( 17 ) can usually not be tolerated, it is finally still expedient, this Zener diode 17 as shown in Fig. 7 through a voltage limiting network without principle-related losses ( 18 ), in which the him supplied energy is fed back into the DC voltage source ( 13 ) to replace. Examples of games are listed in German Patent Application DE 35 38 494 A1.

In a further embodiment, the present invention provides that the potential-connecting DC step-down converters ( 12 ) contained in the above-described configuration are removed and, for each of these DC step-down converters, a potential-isolating DC current controller or a functionally similar one, consisting of DC controllers and converter, is replaced tern composite circuit combination is inserted. For this purpose, the arrangements inserted as replacements must each be able to apply an output current that is dynamically impressed, so its course is largely independent of time.

As an embodiment of such a potential-isolating DC power controller, which can apply a dynamically impressed output current from its principle, Fig. 8 shows a known potential-isolating single-ended flow converter. If the bipolar npn transistor ( 19 ) is switched through in this arrangement, the input voltage U₀ is applied to the primary winding I of the three-winding transformer ( 20 ) outlined there. The voltage appears at its output winding II

which has the consequence that a current i _L <0 flowing through the storage inductor ( 15 ) takes its way via the output winding II of the three-winding transformer ( 20 ) and the flux diode ( 21 ) connected downstream thereof, that is to say by the voltage

is "driven". During this time, the regenerative winding III of the three-winding transformer ( 20 ) due to the blocking demagnetizing diode ( 22 ) leads no current.

If the transistor ( 19 ) is blocked again after the switch-on interval has expired, the magnetization flow through the three-winding transformer ( 20 ) must be applied solely by its regenerative winding III. As a result, a current i _III <0, which starts up via the demagnetizing diode ( 22 ) against the input voltage Uannung and thus subsides. In this state, the voltage is therefore at the output winding II of the three-winding transformer ( 20 )

This has the consequence that the flux diode ( 21 ) blocks and a positive current i _L through the storage inductor ( 15 ) of the free-wheeling diode ( 23 ) is performed. Overall, the desired level is introduced for the mean value of the current i _L through the storage choke ( 15 ) by setting the value required for the arithmetic mean value of the "driving" voltage u _F. The latter happens via the so-called relative duty cycle of the bipola ren npn transistor ( 19 ), ie the ratio of its on interval to the sum of its on and off interval.

A disadvantage of the last described embodiment may be the fact that the short-circuit switch ( 8 ), which supplements the described single-ended flow converter to form a direct current source that can be switched on and off, must be arranged in the output circuit. As a result, this short-circuit switch ( 8 ) requires a potential-free control and may have to be dimensioned for very high voltages or for very high currents.

A further embodiment of the invention therefore provides that if, in the last-described embodiment of the invention, the potential-connecting DC step-down converter ( 12 ) previously contained and for each of these DC step-down switches ( 12 ) is replaced, a potential-separating DC converter or a similarly functioning, potential-isolating circuit combination formed from DC choppers and converters is inserted, preferably such DC choppers or functionally functioning circuit combinations formed from DC choppers and converters are used, the associated storage choke ( 15 ) of which is not only in their output circuit, but, alternatively, can also be arranged in the input circuit. This makes it possible to lay both the storage choke ( 15 ) and the short-circuit switch ( 8 ) in the input circuit of such potential-isolating, identically functioning circuit combinations and converters formed from direct current switches and converters. This relocation must be such that when the in the input circuit short-circuit switch, the output current of the potential-isolating DC chopper or the potential-isolating, identically functioning circuit combination formed from DC choppers and inverters becomes zero, while this output current assumes a value when the short-circuit switch laid in the input circuit is opened, which is determined by the current that flows through the choke installed in the input circuit and through the transmission ratio of that transformer, which functions in the isolating DC regulator or the isolating, identically functioning, a us DC circuit and converters formed circuit combination causes the potential isolation mentioned.

An example of such a potential-isolating circuit combination, which functions as a potential-isolating direct current regulator and is formed from direct current regulators and converters, is shown in FIG. 9. There is initially a DC step-down converter, whose storage choke has been bridged and then removed, connected to a DC voltage source with the voltage U₀. At the output of this modifi ed DC step-down converter ( 24 ), a bridge changer ( 25 ) with output transformer ( 26 ) is connected, which in turn is connected to an uncontrolled bridge rectifier ( 27 ). Finally, the storage choke ( 15 ), which has the inductance L, is inserted into the output circuit of this bridge rectifier ( 27 ). Parallel to the output of this entire arrangement, the short-circuit switch ( 8 ) is finally closed. The series circuit here consisting of the bridge inverter ( 25 ) with output transformer ( 26 ) and the bridge rectifier ( 27 ) has the function of a so-called DC transformer, which, however, only allows energy flow from the inverter to the rectifier. The advantage of this arrangement is the potential separation given; disadvantageous in the manner already described, but the fact may be that the short-circuit switch ( 8 ) in the output circuit is arranged. It is therefore expedient in this arrangement to first store the storage choke ( 15 ) through the DC transformer through on its input side and thus, as shown in FIG. 10, into the output circuit of the DC step-down converter ( 24 ) and in this way into the input circuit to push the overall arrangement. If this means that the overall view seen from the outside should not change this arrangement, this memory choke ( 28 ) in the input circuit of the overall arrangement must have an inductance of size

exhibit. By pushing this storage choke originally located in the output circuit of the overall circuit into the input circuit of the overall arrangement, the prerequisite is also given for the short-circuit switch ( 8 ) located in the output circuit of the overall arrangement to be removed and replaced by a short-circuit switch ( 29 ) which corresponds to GE shown in FIG. 11 is inserted parallel to the output of the DC step-down converter (24) and in this manner in the input circuit of the overall arrangement. By this, now the output of the DC step-down converter ( 24 ) short-circuit switch ( 29 ) connected in parallel, the short-circuit switch ( 8 ) originally inserted parallel to the output of the overall circuit is fully replaced in its effect according to the invention.

To define the currents impressed in the individual DC sources ( 7 ) of the n switchable and deactivatable DC sources ( 6 ) of the device according to the invention, one embodiment of the invention provides that these currents are set in such a way that the expected course of the setpoint for the consumer flow can be approximated within a predetermined tolerance band by the course of the consumer flow that can actually be set with these values.

In many applications, the expected course of the setpoint for the consumer current is already known when the device in question is designed. Then it is appropriate to match the number n of direct current sources ( 6 ) that can be switched on and off as well as the size of the direct currents impressed in their direct current sources ( 7 ) to match this known profile.

An example of such a previously known course of the consumer current setpoint i _{A is} shown in FIG. 12. There, only the values I₁, I₂ and I₃ and the value zero are commanded for the consumer current. An on this history fiction, agreed-date means may, for example, one of three-and-off cash direct current sources (6), said source in the direct current (7) of the first switched on and off DC power source (6) of the current I₁, in the DC power source (7 ) the second on and off switchable direct current source ( 6 ) the current I₂-I₁ and finally Lich in the direct current source ( 7 ) of the third on and off switchable direct current source ( 6 ) the current I₃-I₂ is impressed. If all three direct current sources ( 6 ) that can be switched on and off are in the switched-on state, the consumer current is

i _A = (I₃ - I₂) + (I₂ - I₁) + I₁ = I₃.

If the first and the second direct current source ( 6 ) which can be switched on and off are in the switched-on state and the third, on the other hand, are in the switched-off state, a current flows

i _A = (I₂-I₁) + I₁ = I₂

through the consumer bipolar ( 5 ). If the first direct current source ( 6 ) that can be switched on and off is finally switched on, the consumer current has the value

i _A = I₁.

A suitable choice of the switching states of the three direct current sources ( 6 ) which can be switched on and off makes it possible to set the desired profile according to FIG. 12 for the consumer current i _A.

In many other applications, however, when designing the device according to the invention with regard to the expected course of the setpoint for the consumer current i _A, only the maximum required consumer current I _Amax and the amount of the maximum tolerable deviation | ΔI _A | of the consumer current known from this setpoint. Then it is necessary to design the device according to the Invention such that the entire value range between zero and I _Amax can be traversed in equidistant stages of height I₀ for the consumer current i _A. The step height I₀ is at most twice the amount of the maximum permitted deviation | ΔI _A | of the consumer current i _A from its setpoint.

In the case just described, an embodiment of the invention provides that the group of n direct current sources ( 6 ) which can be switched on and off in the device according to the invention is first divided into a number of m subgroups, m being integer values between 1 and n can assume (1 ≦ m ≦ n). Each of these m subgroups contains k _ν (1 ≦ ν ≦ m) direct current sources ( 6 ) which can be switched on and off, whereby

Must apply, since there are a total of n direct current sources ( 6 ) that can be switched on and off.

The subgroups are in turn characterized in that the currents impressed in the individual direct current sources ( 7 ) of the k _ν on and off switchable direct current sources ( 6 ) of the subgroup with the atomic number ν all have the same value I _ν .

The subgroup with the atomic number ν = 1 thus contains those k 1 switchable and switchable direct current sources ( 6 ), in the individual direct current sources ( 7 ) of which a current of size I 1 is impressed. I 1 is the smallest value of the total m different values of the currents impressed in the direct current sources ( 7 ) of the n direct current sources ( 6 ) which can be switched on and off.

In the other m - 1 groups with the ordinal number ν (2 ≦ ν ≦ m) in each of the direct current sources (7) turn their respective k _ν and off DC power sources (6) each comprise a direct current of the magnitude I _ν is impressed, where I _ν the relationship

obey.

The last-described configuration of the device according to the invention is to be explained in more detail below with reference to three exemplary embodiments. For easier understanding, in each of these three examples a maximum value of the required consumer _current of I _Amax = 504 A and a maximum permissible amount of the deviation of the consumer current from its setpoint of | ΔI _A | = 4 A required. Each of the exemplary embodiments must therefore be designed in such a way that the consumer current i _{A can be set} in 63 steps of 8 A each between the values 0 A and 504 A.

In the first embodiment, the device according to the invention consists of n = 63 direct current sources ( 6 ) which can be switched on and off, and which are all of the same type. This means that the group of 63 direct current sources ( 6 ) that can be switched on and off is no longer divided into subgroups. This can be expressed mathematically by the fact that the group formed from n = 63 direct current sources ( 6 ) which can be switched on and off is divided into m = 1 subgroups. Then applies

which means that the subgroup with atomic number 1 here consists of 63 direct current sources ( 6 ) which can be switched on and off. The current, which is impressed in the individual direct current sources ( 7 ) of the 63 direct current sources that can be switched on and off, must then each have the value I 1 = 8 A.

Particularly advantageous in this embodiment is the fact thing is that for a change of the load current i _{A is} either only one switching of switched on and off DC power sources (6) or only a turning off switched on and off DC power sources must be carried out (6).

It can therefore never occur that certain direct current sources ( 6 ) which can be switched on and off have to be switched on and others have to be switched off at the same time. The consequence of this is that any differences in the switching behavior of the short-circuit switch ( 8 ) of the direct current sources ( 6 ) which can be switched on and off are not noticeable by a disturbing overshoot or undershoot in the course of the consumer current i _A.

On the other hand, in this exemplary embodiment the quite high number of direct current sources ( 6 ) which can be switched on and off can prove to be disruptive.

In the second embodiment, the device according to the invention is built up of n = 6 direct current sources ( 6 ) that can be switched on and off, all of which have a different size. This means that the group of the six direct current sources ( 6 ) that can be switched on and off is divided into m = 6 subgroups, each of which contains a direct current source ( 6 ) that can be switched on and off. Thus applies

k₁ = k₂ = k₃ = k₄ = k₅ = k₆ = 1

and

The first sub-group with the atomic number ν = 1 contains the DC source ( 6 ) which can be switched on and off and in whose DC source ( 7 ) a current of the magnitude I 1 = 8 A is impressed. For the other five subgroups, the relationship (I) gives:

for the direct current source ( 7 ) contained in the second subgroup,

for the direct current source ( 7 ) contained in the third subgroup,

for the direct current source ( 7 ) contained in the fourth subgroup,

for the direct current source ( 7 ) contained in the fifth subgroup and finally

for the direct current source 7 contained in the sixth subgroup.

Despite the gratifying fact that the last-described implementation of the invention with a given step height I₀ and a given maximum current I _Amax manages with the smallest possible number of DC current sources ( 6 ) that can be switched on and off, the following facts can prove to be annoying in some applications: Due to any differences in the switching behavior of the short-circuit switch, the course of the current i _A when transitioning to a new value may have a significant overshoot or undershoot. If, in the arrangement described above, the current i _{A is} to be increased, for example, from 248 A to 256 A, the DC current sources ( 6 ) which can be switched on and off in subgroups one to five must be switched off and at the same time the DC current source which can be switched on and off ( 6 ) be switched on in subgroup six. Is this switching on z. B. due to the storage time of the power electronic switching element used for the relevant short-circuit switch ( 8 ) but ver delays to turn off the other DC sources that can be turned on and off ( 6 ), then a break-in occurs during the course of the arrangement for the duration of this delay Output current to zero. The prerequisite here is that the inductance of the consumer dipole ( 5 ) permits such a high rate of change of the current i _A that the value zero is also fully reached within this storage time.

In the third exemplary embodiment, the device according to the invention is constructed from n = 14 direct current sources ( 6 ) which can be switched on and off and which are divided into m = 2 subgroups. Both sub-groups each contain seven DC sources that can be switched on and off ( 6 ), so it is k₁ = k₂ = 7.

Thus applies

The first subgroup with the atomic number ν = 1 contains those direct current sources ( 6 ) which can be switched on and off and in whose direct current source ( 7 ) a current of the magnitude I 1 = 8 A is impressed. The relationship (I) provides for the value of the currents impressed in the direct current sources ( 7 ) of the subgroup with the atomic number ν = 2:

The last-described exemplary embodiment has the advantage that there, due to a different switching behavior of the short-circuit switches ( 8 ) of the individual direct current sources ( 6 ) which can be switched on and off, during dynamic processes, deviations of the consumer current i _A from its setpoint are significantly lower than in the second embodiment described above. While in the second exemplary embodiment these deviations have a size of 256 A in the most unfavorable case, in the third exemplary embodiment described last they have a maximum value of 64 A.

In addition, the last-described exemplary embodiment has the significant advantage that only two different types of direct current sources ( 6 ) which can be switched on and off are used there. This standardization of the DC sources ( 6 ) that can be switched on and off ( 6 ) with a relatively modest total number of DC sources ( 6 ) that can be switched on and off ( 6 ) significantly reduces the effort both in the development and in the implementation of the device according to the invention.

Claims (7)

1. A device for supplying a consumer bipole ( 5 ) with an impressed direct current which can be set in a number of stages, characterized in that
that a group of n (n = 2, 3,...) that can be switched on and off DC current sources ( 6 ) is connected to this consumer pole ( 5 ) and
that the n on and off switchable DC sources ( 6 ) are each constructed such that a switch ( 8 ), hereinafter referred to as short-circuit switch, is arranged in parallel with an embossed DC source ( 7 ), via which the current of the impressed DC source ( 7 ) can flow when this short-circuit switch ( 8 ) is closed and that such a DC source ( 6 ) that can be switched on and off is thus in its switched on state when its short-circuit switch ( 8 ) is open, whereas it is in its switched-off state if your short-circuit switch ( 8 ) is closed and characterized by
that in series with each of these n on and off direct current sources ( 6 ) each have a diode ( 9 ), hereinafter referred to as coupling diode, is connected and
that the resulting n series connections, each of which can be switched on and off a direct current source ( 6 ) and a decoupling diode ( 9 ), are connected in parallel with the load pole ( 5 ) and
that the individual decoupling diodes ( 9 ) are each poled so that the current of the associated switchable and off switchable direct current source ( 6 ) can flow through the consumer dipole ( 5 ) when this switchable on and off switchable direct current source ( 6 ) in its switched on state located and
that each of these n direct current sources ( 6 ) that can be switched on and off has a fixed value, clearly assigned to the relevant direct current source that can be switched on and off, of the current impressed in its direct current source ( 7 ) and
be that the switching states of power sources of these n switched on and off DC (6) are each set such that the the total current flowing through the Verbraucherzweipol (5) Power, hereinafter referred to load current, close to a for this predetermined nominal value as possible, namely as close as In view of the principle given in the arrangement described, the actual value of the consumer current can be executed. 2. Device according to claim 1, characterized in that a change in the switching states of the n on and off switchable direct current sources ( 6 ) is carried out only at uniform, at equidistant intervals consecutive times. 3. Device according to claim 1 or 2, characterized in
that the direct current source ( 7 ) of the n on and off switchable direct current sources ( 6 ) each consist of a potential-connecting, fed from a direct voltage source DC step-down converter ( 12 ) and
that the arithmetic mean value of the output current of such a DC step-down converter ( 12 ) is adjusted to a fixed, constant value by specifying the duty ratio of the electronic switch ( 14 ) contained therein and
that the inductance of the storage choke ( 15 ) of such a DC step-down converter ( 12 ) is dimensioned so large that the course of its output current does not leave a predetermined tolerance band. 4. Device according to claim 3, characterized in
that the DC step-down converter ( 12 ) contained therein is removed and, instead, a potential-isolating DC current regulator or a similarly functioning circuit combination composed of DC current regulators and converters is inserted and
that the alternatively inserted arrangements can each apply an output current based on their principle, which is dynamically impressed, so its course is largely independent of time. 5. Device according to claim 4, characterized in
that if a potential-isolating direct current controller or a similarly functioning, potential-isolating circuit combination composed of direct current regulators and converters is inserted, preferably such direct current regulators or similarly functioning circuit combinations composed of direct current regulators and converters are used, their associated storage choke ( 15 ) not only in their output circuit, but, alternatively, can also be arranged in their input circuit and characterized in that
that then both this storage inductor ( 15 ) and the short-circuit switch ( 8 ) are preferably moved into the input circuit of such potential-isolating DC controllers or potential-isolating, functionally functioning, DC controllers and converters to composite circuit combinations in such a way that when the in the respective input circuit installed short-circuit switch ( 29 ) the output current of the potential-isolating DC chopper or the potential-isolating, identically functioning circuit combination composed of DC choppers and converters becomes zero, while this output current when opening the short-circuit switch ( 29 ) laid in the respective input circuit becomes a value assumes that is determined by the current which flows through the storage choke ( 28 ) laid in the input circuit and by the transformation ratio of that transformer ( 26 ) which is in the electrically isolating n DC chopper or the potential-isolating circuit, which functions in the same way and is composed of DC choppers and inverters, effects the ge-mentioned potential isolation. 6. Device according to one of claims 1 to 5, characterized in that the values of the in the individual direct current sources ( 7 ) of the n on and off switchable direct current sources ( 6 ) are each imprinted currents such that an expected course of the setpoint for the consumer current can be approximated within a predetermined tolerance band by the course of the consumer current that can actually be set with these values. 7. Device according to claim 6, characterized in
that the group of n direct current sources ( 6 ) which can be switched on and off is divided into a number of m (1 ≦ m ≦ n) subgroups and
that in each of these m subgroups k _ν on and off switchable direct current sources ( 6 ) are included and
that the currents impressed in the individual direct current sources ( 7 ) of the k _ν on and off switchable direct current sources ( 6 ) of the subgroup with the ordinal number ν all have the same value I _ν and
that in the subgroup with the atomic number ν = 1 those k₁ on and off switchable direct current sources ( 6 ) are contained, in each of which a single direct current source ( 7 ) is characterized by a current of size I₁, where I₁ is the smallest value of the total m ver represents different values of the currents impressed in the direct current sources ( 7 ) of the n direct current sources ( 6 ) which can be switched on and off and
that in the other m-1 groups in each of the direct current sources ( 7 ) their respective k _ν (2 ≦ ν ≦ m) direct current sources that can be switched on and off ( 6 ) are each impressed with a direct current of the magnitude I _ν (2 ≦ ν ≦ m) where I _{ν of} the relationship obey.