WO1999053602A1

WO1999053602A1 - Power converter with actively controllable commutation

Info

Publication number: WO1999053602A1
Application number: PCT/EP1999/002383
Authority: WO
Inventors: Andreas Boehringer; Jürgen FRANTZHELD
Original assignee: Andreas Boehringer; Frantzheld Juergen
Priority date: 1998-04-15
Filing date: 1999-04-08
Publication date: 1999-10-21
Also published as: DE19845995A1; WO1999053602A9

Abstract

The invention relates to a power converter with actively controllable commutation. Said power converter is connected to an a/c or three-phase voltage system and is preferably configured in a bridge circuit. The invention is characterised in that the main current valves of the power converter have a reverse blocking action and are constantly controllable in the forward direction and in that if, after the next valve to carry the current has been activated, the commutation voltage which is effective in the commutation circuit from the last valve to carry the current to the next becomes unacceptably high in terms of the effects it causes on the a/c side, a constant, variable voltage which is also positive in the direction of the targeted current flow and optionally, current-dependent, is set between the main current electrodes of the valve which is next to carry the current by influencing the controlled system of said valve. This voltage is set at a value high enough to reduce the commutation voltage which is effective in the commutation circuit from the last valve to carry the current to the next to the extent that the effects it causes on the a/c side are admissible.

Description

Power converter with commutation that can be actively influenced

The present invention relates to a converter, in particular a converter with commutation which can be actively influenced.

To introduce the description of the invention presented here, FIG. 1 shows a thyristor converter (1) designed in a bridge circuit, which is connected to a three-phase voltage system (2) via its AC-side external connections A ^, Ag and Aj. For the latter, the usual substitute representation is selected, which consists of three impressed star voltage sources e ^ (3), e ^ (4) and ej- (5), which have three chokes L ^ (6) to take into account the inductive internal resistance of the three-phase voltage system (2) ), Lg (7) and Lr (8) are connected downstream, each of which has the inductance L. The ohmic internal resistance of the three-phase voltage system (2) is assumed to be negligibly small. This assumption is also based on the ohmic resistances of all connecting lines and other components that occur in the context of this description. Furthermore, the forward voltage of the thyristors used is assumed to be negligible. The same applies to the forward voltages of all diodes and fully switched-on insulated gate bipolar transistors (IGBT), which are still used in the context of this description. These prerequisites may be met because the forward voltages mentioned and all ohmic resistances in question have no significant influence on the commutation processes of interest in the present context.

The three-phase bridge circuit shown in FIG. 1 contains a total of six thyristors (9). They are identified by the small letters a to f in the order in which they participate in the conduct of the rectified current i. A total of six different commutations (current transfers) occur in this arrangement; those from thyristor a to thyristor c, those from b to d, those from c to e, those from d to f, those from e to a and those from f to b. Because these commutations basically As stated immediately, it is sufficient for the considerations below to illuminate one of them in a representative manner for all.

In the following, therefore, only the commutation (current transfer) of the rectified current i from thyristor a to thyristor c will be considered, which is therefore also referred to below as "considered commutation". Before this "considered commutation" begins, the rectified current i flows according to the current path shown in dash-dotted lines in FIG. 1 from the rail of the DC intermediate circuit (10) shown in FIG. 1 below via the thyristor b, the lower choke L _j (8), the Star voltage source e- | - (5), the star voltage source e ^ (3), the upper choke Ln (6) and via the thyristor a to the upper rail of the DC link (10). The commutation from thyristor a to thyristor c begins when thyristor c is released by an ignition pulse and the condition e ^> e ^ is fulfilled. Then a current i _c begins to form via the voltage source e ^ (4), the central choke Lg (7) and the thyristor c, which is shown in broken lines in FIG. 1. At the same time, the dotted current L d flowing through the star voltage source e ^ (3), the upper choke Ln (6) and the thyristor a begins to decrease. The sum of the two currents L α and LC is the rectified current i. The commutation considered is complete when i = 0 and thus i _c = i.

The current i ^ flowing through the thyristor b, the lower choke Lj (8) and the star voltage source ej (5) remains unaffected by the commutation under consideration. For the latter, immediately before the considered commutation from thyristor a to thyristor c, during this commutation and immediately afterwards = i. As a result, the circuit part (11) shown at the top left in FIG. 1 for the analysis of the commutation under consideration from thyristor a to thyristor c can be detached from the overall arrangement and viewed separately. For this project, the circuit part (11) mentioned is again clearly shown in FIG. 2.

As can be seen directly from FIG. 2, the desired commutation of the current i from the current-carrying thyristor a to the thyristor c subsequently used to conduct current will then only start as desired when the time at which the thyristor c is released by an ignition pulse , which is positive commutation voltage u ^ = eς - e ^ in the commutation circuit under consideration from the current-carrying thyristor a to the thyristor c subsequently intended for current carrying, or is at least in the process of changing from negative to positive values. From Fig. 2, however, it is also immediately clear that if the latter is released by an ignition pulse to initiate the desired commutation from the current-carrying thyristor a to the thyristor c subsequently intended for current carrying, a positive condition is given under the condition u ^> 0 Current i _c begins to develop. Then both thyristors, a and c, are conductive at the same time for a short period of time. In the meantime, the rectified current i is kept practically constant by the intermediate circuit choke (12) contained in the direct current intermediate circuit with the inductance L ^. The current L through the current-carrying thyristor a will therefore decrease to the same extent as the current i _{c increases} through the thyristor c subsequently intended to carry current. Since the two chokes L ^ (6) and Lg (7) have the same inductance, the commutation voltage u ^ = eg - e ^ will therefore each fall in half on the two chokes immediately in series with the thyristors a and c Split Lr ^ (6) and Lg (7). The positive voltage - • u ^ at the choke L ^ is directed against the current i flowing there and consequently endeavors to increase this current i

1 decrease. - In contrast, the positive voltage is - u ^ at the throttle Lς in the direction of the flowing current i _c there addressed and consequently strives to the latter to increase. However, these tensions have another and usually undesirable consequence. While the conductor voltage Uι between the two AC-side external connections Ag and A ^ of the converter (1) has a sinusoidal curve according to Uι = eg - e both immediately before and immediately after the commutation under consideration, this conductor voltage suddenly takes the value zero during the commutation under consideration , so it changes abruptly by the value ^U K ^{= e} S " ^e R _". We shall come back to this effect below. 3 shows the two star voltages e ^ and eg appearing in FIG. 2 over the normalized time τ = ω ^• t. The commutation voltage ^U K ^{= e} S " ^e R is shown below. Ω is the electrical angular frequency of the three-phase voltage system (2). The origin τ = 0 of the standardized time is chosen so that it characterizes the situation en = e> 0. The so-called "natural" ignition timing for the thyristor c is characterized by τ = 0. From this natural ignition timing up to the actual ignition of the thyristor c, the so-called ignition delay angle α is counted, which is also plotted in FIG recognizes, the situation e ^ = eg <0 is thus characterized by τ = 180 ° and by α = 180 °. The conventional thyristor converter (1) described has two fundamental disadvantages which are based on the principle. The first serious disadvantage is that the commutation considered from thyristor a to thyristor c only in the normalized time range from τ = 0 to τ = 180 ° (and then again from τ = 360 ° to τ = 540 °, from τ = 720 ° to τ = 900 ° etc.) can be initiated and must also be completed in this time interval. It is therefore only possible to set the ignition delay angle in the range 0 <α <180 °. As a result, such a thyristor converter (1) generally takes up inductive reactive power at its external connections on the AC side. The conventional thyristor converter (1) is basically unable to perform the complementary task, i.e. the delivery of inductive reactive power.

A particularly pressing task of converter technology currently is to manage the energy exchange between three-phase voltage systems and so-called "slim" DC voltage intermediate circuits. Such DC voltage intermediate circuits primarily supply pulse inverters, which in turn usually feed three-phase drives. The "slim" DC voltage intermediate circuit consists only of a transverse capacitor, the capacitance of which is just sufficiently dimensioned that it can keep the intermediate circuit voltage dynamically constant during switching operations in the pulse-controlled inverter. However, this capacitance is so small that the rectified voltage of those converters via which the energy is exchanged with the three-phase voltage system is not appreciably smoothed. The fact that the transverse capacitor is inserted directly between the DC terminals of the feeding converter means that the latter must be operated with an ignition delay angle of α <0. This feed-in converter, which is referred to below as the feed-in converter, can thus be implemented very simply as a diode rectifier. To this feed-in converter, a converter provided for the feedback must be connected antiparallel on the DC side. In view of the direct connection of the transverse capacitor and the fact that the feeding diode rectifier works with α = 0, this converter, which is intended for the regenerative energy supply, which is called the regenerative current converter in the following, should be operated with an ignition delay angle of α «180 °. As already explained, the conventional thyristor converter (1) described cannot do this. The described problem cannot be solved satisfactorily even if the thyristor power converter (1) mentioned above, the only switchable thyristors contained therein are replaced by their also switchable variants by so-called gate-turn-off thyristors (GTO's). Then in the regenerative current judge namely not the desired direct commutation from the current-carrying GTO to the GTO subsequently intended for carrying current, but only an indirect commutation, in which the current supply must be taken over in the meantime by one of the diodes of the feed converter. In this case, however, large, heavy and therefore expensive chokes are required on the AC side, which are highly undesirable for both technical and economic reasons.

The second serious disadvantage of the conventional thyristor converter (1) described is the effect already described that the conductor voltage Ui = eg - en suddenly takes on the value zero during the commutation under consideration, so that it jumps around the value u ^ = eg - e ^ changed. These voltage jumps are greatest when the described conventional thyristor converter (1) is operated with an ignition delay angle of α <90 °. As can be seen from FIG. 3, these voltage jumps then assume the full peak value of the line voltage. Quite apart from the associated stress on the thyristor converter (1) itself, the operator of the three-phase voltage system (2) generally prohibits such high voltage jumps for reasons of electromagnetic compatibility (EMC). According to the DIN / VDE regulations, these voltage jumps may not exceed Δe = 0.2 ^■ ü. (20% of the peak value above the conductor voltage). To comply with this regulation, so-called pre-chokes have been installed upstream of the conventional thyristor converter described, the inductance of which has to be at least four times as large as the inductance Lj of the three chokes Ln (6), Lg (7) and Lj (8), which have the inductive internal resistance of the three-phase voltage system (2) represent. As a result, these pre-chokes are considerably large, heavy and therefore also expensive. In recent times, they have been regarded as particularly disruptive because they stand in the way of an important development trend that involves the complete integration of the feed-in converter, the regenerative converter, the DC link, the pulse inverter fed from the latter, and the supplied three-phase motor into a compact overall drive system with a direct three-phase connection to the target Has.

The problem underlying the present invention is to provide a power converter which overcomes the disadvantages described above, in particular that with an ignition Delay angle of 180 ° is operable and requires no or only relatively small pre-chokes and is therefore inexpensive to manufacture.

The converter with an actively influenced commutation presented with the present invention, connected to an AC or three-phase voltage system, preferably implemented as a bridge circuit, overcomes the two described, principle-related and serious disadvantages of the conventional thyristor converter (1) by virtue of a fundamentally new approach.

Further advantages, features and details of the invention result from the subclaims and the following description, in which several exemplary embodiments are described in detail with reference to the drawings. The features mentioned in the claims and in the description can each be essential to the invention individually or in any combination.

1 shows a thyristor converter (prior art) implemented in a bridge circuit,

FIG. 2 shows a section of the circuit of FIG. 1 (prior art),

3 shows the time course of the voltages e _R , e _s and u _κ (prior art),

4 shows a first exemplary embodiment of a converter with actively influenced commutation,

5 shows a section of the circuit of FIG. 4,

6 shows the time profile of the voltages e _R , _es and u _κ and the default values for u _a and u _c ,

7 shows the voltage and current profiles with an ignition delay angle α = 30 °,

8 shows the voltage and current profiles similar to FIG. 7 with a partially stretched time axis and assuming a much smaller inductive resistance of the voltage system,

9 shows the voltage and current profiles with an ignition delay angle α = 210 °,

10 shows the voltage and current profiles with an ignition delay angle α = 165 °,

1 1 shows the converter of FIG. 4 with additional chokes, 12 shows the voltage and current profiles of the converter of FIG. 11 at an ignition delay angle α = 210 °,

13 shows a second exemplary embodiment of a converter with actively influenced commutation for a DC voltage intermediate circuit,

14 shows a section of the circuit of FIG. 1 3,

15 shows the equivalent circuit diagram for the arrangement according to FIG. 14,

16 shows the voltage and current profiles of the converter of FIG. 13 with an ignition delay angle α = 25 °,

1 7 shows the voltage and current profiles of the converter of FIG. 13 with an ignition delay angle α = 180 °,

18 shows a circuit with two converters connected to the same three-phase voltage system,

FIG. 19 shows a circuit of FIG. 1 simplified for certain applications.

18,

20 shows a variant of the circuit of FIG. 1 3,

21 shows a variant of the circuit of FIG. 4,

22 shows a further variant of the circuit of FIG. 4,

FIG. 23 shows a further variant of the circuit of FIG. 13.

In FIG. 4, in a modification of the arrangement shown in FIG. 1, the thyristor converter (1) originally contained therein, which is implemented in a bridge circuit, is replaced by a converter with an actively influenced commutation (13), which is likewise in the example of a bridge circuit. This converter with actively influenced commutation (1 3) is initially characterized in that main flow valves are used instead of the thyristors (9), which block in the reverse direction and are continuously controllable in the forward direction. Such main flow valves, which block in the reverse direction and are continuously controllable in the forward direction, are currently already developed as reverse blocking insulated gate bipolar transistors, so-called RSIGBTs, but are not yet commercially available and therefore do not yet have their own circuit symbol or symbol. As a result, in the present description, such main flow valves are always referred to as reverse blocking insulated gate bipolar transistors or, in short form, as RSIGBTs, and, as has already been done in FIG. 4, in the form of the series connection of an insulated gate bipolar transistor which behaves identically to the outside ( IGBT) and a diode. These RSIGBT's (14) are also shown in that order in FIG small letters a to f marked in which they participate in the management of the rectified current i.

Under the conditions that have been met, analogously to the procedure for the conventional thyristor converter (1), the circuit part (15) shown at the top left in FIG. 4 for analyzing the commutation in question from RSIGBT a to RSIGBT c can be detached from the overall arrangement and viewed separately . For this project, this circuit part (1 5) is again clearly shown in Fig. 5. It has already been taken into account that in this arrangement, if the two currents i and i through the two RSIGBT (14) a and c are greater than zero, the main current electrodes of the two RSIGBT (14) can suitably influence their control paths Voltages u _a > 0 (for RSIGBT a) and u _c > 0 (for RSIGBT c) can be set up.

The key idea of the invention presented herewith is partly that the thyristors (9) of the conventional thyristor converter (1) are replaced in the manner already described by main flow valves which block in the reverse direction and are continuously controllable in the forward direction. On the other, much more important part, this key idea consists in influencing these main flow valves when commutating via their control paths in such a way that voltage conditions occur at the chokes Ln (6), Lg (7) and Lj (8), which occur at any ignition delay angle α cause a commutation that runs successfully and as quickly as possible while observing the condition that the relevant network feedback regulations are certainly not yet violated. The invention presented here is therefore able to dispense with large, heavy and therefore also expensive pre-chokes. Regardless of this, it can be operated with any ignition retardation angle and not only with those in the range 0 ° <α <180 °. So you can e.g. can also be operated with α «180 °, which is urgently desired for the regenerative converter already mentioned, but unfortunately has so far not been able to be realized.

The commutation under consideration from RSIGBT a to RSIGBT c will take place as quickly as possible when the largest, still permitted voltage against the direction of current flow is at the choke L ^ (6) and the largest, still allowed voltage at at the choke Lg (7) Current flow direction is present. Because of i _a + i _c = i «const. the amounts of these two tensions have to be equal. In total, the amounts voltages do not exceed the above-mentioned value Δe. Thus, for the fastest possible commutation on the inductor L _R (6) contrary to that given there

1 current flow direction the voltage - ^• Δe and at the choke Lg (7) in the given there

Current flow direction to apply the voltage ^~ - Δe, as has also already been entered in FIG. 5. The second Kirchhoff rule supplies the relation u _c - u _a = u ^ - Δe for the mesh shown in FIG. 5. If this difference u ^ - Δe is positive, the voltage u _a = 0 must be set on the RSIGBT a and the then positive voltage u = u ^ - Δe on the RSIGBT c. If this difference u ^ -Δe is negative, the voltage u = 0 must be set at RSIGBT c and the then positive voltage u = - (u ^ -Δe) at RSIGBT a.

In the following, u _a γ and u _c y denote the default values for the voltages u _a and u _{c mentioned} . These default values u _a γ and u _c y are shown in the lower diagram in FIG. 6 as functions of the standardized time τ. In those periods in which the default value uy has values other than zero, the default value u _c y must be set for the voltage u at the RSIGBT c and for the voltage u _a at the RSIGBT during the time interval from a desired start of commutation to the successful completion of this commutation a maintain the value zero; After this commutation has been successfully completed, the RSIGBT c must be switched on fully and the RSIGBT a must be switched off. In the manner described above, a so-called "delayed" or "braked" commutation is effected, which proceeds more slowly than when it is not actively influenced in the manner described.

In those periods in which the default value u _a y has values other than zero, the default value uy must be set for the voltage u at the RSIGBT a and for the voltage u at the RSIGBT c during the time interval from a desired start of commutation to the successful completion of this commutation to bring about the value zero; After this commutation has been successfully completed, the RSIGBT a must be switched off and the RSIGBT c must be left in its fully switched-on state. In this way, just described, a so-called "accelerated" or, if it would not have started by itself, a so-called "activated" commutation, which takes place faster or comes about at all, because it actively influences in the manner described becomes.

From the above it is immediately clear that the voltage ratios indicated by FIG. 5 and desired during the commutation under consideration on the Throttles L ^ (6) and Lg (7) can be brought about by the procedure according to the invention for any ignition delay angle α, and by no means only for those in which u ^ has positive values.

As an example of a "delayed" or "braked" commutation, those voltage and current profiles are shown in FIG. 7 as they result in a converter (13) designed according to the illustration in FIG an ignition delay angle α = 30 ° is operated in the manner according to the invention described above. For the sake of a better overview, the courses of the voltages u _a and u _c and the currents i _a and i _{c are} only drawn in the time range that is relevant for the commutation under consideration. In the operating state identified by FIG. 7, the converter according to FIG. 4 draws active power and inductive reactive power on its three-phase voltage side and outputs power on its direct current side. For the illustration in Fig. 7, the inductive internal resistance of the three-phase voltage system (2), i.e. the inductance of the three chokes L _R (6), Lg (7) and Lj (8), was deliberately chosen to be exceptionally large, so that the overlap duration u was so great becomes that the processes described can be clearly seen in the two lower of the diagrams shown in Fig. 7. In practice, however, the inductive internal resistance of the three-phase voltage system (2) will generally be so small that the "considered commutation" always takes place so quickly in view of its active influence that the voltages e ™, eg and he do not change appreciably during this time . In order to be able to still clearly recognize the current and voltage conditions that then arise during the “considered commutation”, the following procedure was followed for the diagrams shown in FIG. 8. With the beginning at a point in time τ- _j which is very short of the ignition point τ = α of the RSIGBT's c and with the end at a point in time Ty which very shortly follows the completion of the "considered commutation", the time scale is greatly increased, so that commutation, which takes place extremely quickly, is clearly recognizable. The time interval in which the time scale is very greatly enlarged is τ = τ- _| at its beginning and at its end τ = τy each bounded by a solid vertical line and marked in Fig. 8 at the top in the direction of the abscissa by a hatched bar. For τ> τ ^ the original time scale is used again, which is also the basis for the sketched diagrams for τ <τ-. 8 shows those voltage and current profiles as they result in a converter (13) according to the invention, which is shown in FIG. 4, provided that it has an ignition delay angle α = 30 ° in the described, operated according to the invention with "delayed" or "braked" commutation. Only the inductive internal resistance of the three-phase voltage system (2) is much smaller for the diagrams in FIG. 8 - and thus taking into account the practical conditions - assumed than for the diagrams shown in FIG. 7.

As an example of an “activated” commutation, those voltage and current profiles are shown in FIG. 9, as they result in a converter according to the invention, designed according to the illustration in FIG. 4, provided that it has an ignition delay angle α = 210 ° in the above described, operated according to the invention. For the sake of a better overview, the curves of the voltages u and u and the currents i _a and i _{c are} only drawn in the time range that is relevant for the commutation under consideration. In addition, for the diagrams sketched in FIG. 9, that form of representation with a time scale that was very greatly enlarged in the time interval from τ = τ to τ = τ ^, which is also the basis of the diagrams in FIG. 8, is selected. In the operating state identified by FIG. 9, the converter (1 3) according to FIG. 4 draws power on its DC side and emits active power and inductive reactive power on its three-phase side. The latter is fundamentally not possible with the conventional thyristor converter. Both for the operating state identified by FIG. 8 and for that according to FIG. 9, a converter (13) designed according to the invention was assumed, as shown in FIG. 4. The converter (1 3) shown in FIG. 4 can therefore be used to carry out both a "delayed" or "braked" commutation and an "activated" or "accelerated" commutation. However, it can also be advantageous to operate the converter (13) according to the invention shown in FIG. 4 during one and the same commutation process both with "delayed" or "braked" commutation and with "activated" or "accelerated" commutation. In this sense, those voltage and current profiles are shown in FIG. 10 as they result in a converter (1 3) according to the invention, which is designed according to the illustration in FIG. 4, provided that it initially has an ignition delay angle α = 1 65 ° with "delayed" or "braked" commutation and then operated with "accelerated" commutation in the manner according to the invention. For the diagrams sketched in FIG. 10, an extraordinarily large inductive internal resistance of the three-phase voltage system (2) was used again in order to be able to present the conditions in a clear manner. For the diagrams in FIG. 10, a temporary, very large increase in the time scale was deliberately avoided. From what has been explained so far, it became clear that the converter (1 3) according to the invention with actively influenced commutation can completely dispense with so-called pre-chokes. However, he does not enforce such a waiver. The converter (13) according to the invention with actively influenced commutation can also be operated with pre-chokes additionally inserted. For this purpose, FIG. 1 1 shows the converter (1 3) according to the invention according to FIG. 4 after three pre-chokes (16) have been connected upstream of it on the three-phase side. From Fig. 1 1 it is immediately clear that now two chokes (L _R (6) and L _VR (17); Lg (7) and Lyg (18); Lj (8) and L _yτ (19)) directly in Series are connected. If the inductive internal resistance of the three-phase voltage system (2), i.e. the inductances L _R (6), Lg (7) and Lj (8), and the inductances of the pre-chokes (16) ^L VR ^ ⁷ ^ ' ^L VS ^ ^ ^{and L} VT ^ ^ are for example of equal size, twice as large voltages must by Inventive ^¬ proper power converter (13), then, in comparison with the embodiment shown in Fig. 4 arrangement are applied to this series circuits each consisting of two reactors, without the DIN / VDE Regulations are violated. For the situation that arises in this case, that is to say for Δe = 2 ^• Δe, those voltage and current profiles are shown in FIG. 12 which result in a power converter (13) designed according to the illustration in FIG is operated with an ignition delay angle = 210 ° in the manner according to the invention. For the diagrams sketched in FIG. 12, the form of representation with a time scale that has been greatly enlarged in the time interval from x = xi to x = X2 is chosen, which is also the basis of the diagrams in FIG. 8 and in FIG. 9.

The previous explanations in the present description assume that a DC link (10) with the DC link choke (12) with the inductance L _{j is} connected to the converter (1 3) according to the invention as shown in FIG. 4 on the DC side. However, it was already mentioned at the beginning that a large, technically important field of application is characterized in that the direct current intermediate circuit (10) connected on the direct current side in FIG. 4 is replaced by a preferably "slim" direct voltage intermediate circuit. The arrangement thus created is shown in FIG. 13. It has replaced the DC link (10) with the DC link choke (12) in place of FIG. 4, a DC link (20) with the DC link capacitor (21) with the capacitance C ^. Since the individual commutations are basically the same in this arrangement as well fen, it is entirely sufficient for the following considerations to illuminate one of these commutations representative of all.

In the following, the commutation of the rectified current i from the RSIGBT a to the RSIGBT c will again be considered, which is therefore referred to again as "considered commutation". Before this "considered commutation" begins, the rectified current i flows in accordance with the current path shown in dash-dotted lines in FIG. 1 3 from the rail of the DC voltage intermediate circuit (20) shown in FIG. 1 3 below via the RSIGBT b, the lower choke L _j (8) , the star voltage source e _j (5), the star voltage source e _R (3), the upper choke L _R (6) and via the RSIGBT a to the upper rail of the DC link (20). In the event that the "considered commutation" is not actively influenced, the current transfer from the RSIGBT a to the RSIGBT c begins when the RSIGBT c is switched on due to an increase in its gate-emitter voltage and the condition eg> e _R is satisfied. A current i then begins to form via the star voltage source eg (4), the central choke Lg (7) and the RSIGBT c, which is shown in broken lines in FIG. 13. At the same time begins the dotted registered, en over the star voltage source (3), the upper throttle Ln (6) and to reduce the current flowing RSIGBT a i _a. The sum of the two currents i and i is the rectified current i. The "considered commutation" is complete when i = 0 and i _c = i. The "considered commutation" only indirectly affects the current flowing through the RSIGBT b, the lower choke L _j (8) and the star voltage source ej (5). For the latter, immediately before the "considered commutation" from RSIGBT a to RSIGBT c, i ^ = i during this commutation and immediately thereafter. As a result, the circuit part (22) framed in long-short-short in FIG. 1 for the analysis of the "considered commutation" from the RSIGBT a to the RSIGBT c can be separated from the overall arrangement and viewed separately. For this project, the circuit part (22) mentioned is again clearly shown in FIG. 14.

Under the generally permissible condition that the "considered commutation" always takes place so quickly in view of its active influence that the voltages en, eg and ej do not change appreciably during this time, and that the voltage u ^ ^{at the} intermediate circuit capacitor ( 21) with the capacitance C ^ not significantly changed, the equivalent circuit diagram shown in FIG. 15 is valid for the arrangement according to FIG. 14. The index 0, which is applied to the voltages ^e R0 ' ^e S0 ^unc ' ^U K0, indicates the value of these voltages at the time of Switching the RSIGBT's c. In Fig. 1 5 it is already taken into account that in this arrangement, when the two currents i _a and i _c through the two RSIGBT's a and c are greater than zero, the main current electrodes of these two RSIGBT's are able to influence their control paths in a suitable manner Voltages u _a > 0 (for RSIGBT a) and u> 0 (for RSIGBT c) can be set up. The voltages then applied to the chokes Ln (6), Lg (7) and Lj (8) can be determined very easily using the overlay theorem. The voltage swept at the choke Ln (6) against the current flow direction given there has the value - - (U _K Q - U _C + 2 - u _a ). The voltage swept across the choke Lg (7) in the current flow direction given there has the value

1

- • (2 • UI / Q - 2 • u + u _a ). At the throttle Lj (8) one appears in the one given there

1 Current flow direction swept voltage - - (u _K Q - u _c - u _a ). As can be seen directly from the above-mentioned voltages and FIG. 15, for a "delayed" or "braked" commutation during the time interval from a desired start of commutation to the successful completion of this commutation for the voltage u _c at the RSIGBT c is a positive default value u _c y and keep the value zero for the voltage u at RSIGBT a. In this case, the commutation takes place more slowly than if it is not actively influenced in the manner described. Under these

Circumstances, the current acting on the choke L _R (6), contrary to the current

1 flow direction swept voltage, the value - - (U ^ Q - U _C ). The voltage which is effective at the choke Lg (7) and swept in the direction of current flow there then has the value 2 - • (UI / Q - U). At the throttle Lj (8) appears one, in the current flow direction given there

1 direction swept voltage - - (u ^ Q - u _c ). The DI N / VDE regulations are among these

Under certain circumstances, it will not be violated as long as the voltage value ~ - ß - (U ^ Q - u) is smaller than the maximum permissible voltage value Δe mentioned earlier. The fastest possible commutation in compliance with the DI N / VDE regulations requires for

Voltage u at RSIGBT c under these circumstances therefore a default value uy = UιxQ - Δe - from the voltages given above and Fig. 1 5 the

further shows that for an "activated" or "accelerated" commutation during the time interval from a desired start of commutation until the successful completion of this commutation, a positive default value uy must be set for the voltage u _a at the RSIGBT a and the value for the voltage u at the RSIGBT c zero is to be brought about. The commutation then runs faster or comes about in the first place because it is actively influenced in the manner described. In this case it has the throttle

L _R (6) effective, the arrow opposite to the direction of current flow there

1 value - • (UI / Q + 2 • u _a ). The effective at the choke Lg (7), in the current given there Flow direction swept voltage has the value - ^• (2 ^• u _KQ + u _a ). At the choke Lj (8) appears a voltage swept in the current flow _direction given there - • (u _κo - u). For the two cases α «0 ° and α« 180 ° that are of most interest in practical use, the DIN / VDE regulations are not violated under these circumstances as long as the voltage value is - - Λ 3 ^• u _a smaller than the previously mentioned maximum permissible voltage value Δe. Under these circumstances, the fastest possible commutation in compliance with the DIN / VDE regulations therefore requires a default value u _a y = Δe - - - 3 for the voltage u at the RSIGBT a.

As an example of a "delayed" or "braked" commutation, those voltage and current profiles are shown in Fig. 1 6, which result in a converter (1 3) according to the invention, as shown in Fig. 13, provided that this with an ignition delay angle α = 25 ° is operated in the manner according to the invention described above. For the sake of a better overview, the courses of the voltages u _a and u _c and the currents i _a and i _{c are} only drawn in the time range that is relevant for the commutation under consideration. In addition, for the diagrams sketched in FIG. 16, that form of representation with a time scale that was greatly enlarged in the time interval from x = x- to x = X was chosen, which was chosen for the diagrams in FIG. 8 for the first time.

In the operating state identified by FIG. 1 6, the converter according to FIG. 13 draws active power and inductive reactive power on its three-phase side and outputs power on its direct current side.

As an example of an "activated" commutation, those voltage and current profiles are shown in FIG. 1 7 as they result in a converter (13) according to the invention, as shown in FIG. 13, provided that it has an ignition delay angle α = 180 ° is operated in the manner described above, according to the invention. For the sake of a better overview, the courses of the voltages u and u as well as the currents i and i _{c are} only drawn in the time range that is relevant for the commutation under consideration. In addition, for the diagrams sketched in FIG. 1 7, that form of representation with a time scale that was greatly enlarged in the time interval from x = x- to x = Xy was chosen, which was chosen for the diagrams in FIG. 8 for the first time. In the operating state identified by FIG. 17, the converter according to FIG. 13 draws power on its direct current side and emits active power and inductive reactive power on its three-phase voltage side. A further, novel arrangement, which is highly advantageous in terms of its performance for practical use, arises when two converters with actively influenced commutation, as shown in FIG. 18, are connected together to the same three-phase voltage system and are connected antiparallel on their respective DC voltage side. In the arrangement according to FIG. 18, the dc voltage sides connected in anti-parallel are in turn connected by way of example to the two connections of a dc intermediate circuit (20). This arrangement, which overall is not very complex, permits technically very significant four-quadrant operation, that is to say both a reversal of the current and voltage directions on their DC voltage side. If the current i is to have positive values in the arrangement according to FIG. 18, the converter II (23) contained in FIG. 18 is blocked. This positive current i is then carried by the converter I (24) in the arrangement according to FIG. 18. If its ignition delay angle α. | then, for example, set to the value = 0 °, a negative voltage u ^ is obtained - but if this ignition delay angle is, for example, to the value ct _| = 180 °, there is a positive voltage Uς. Analogously to this, if the current i is to have negative values in the arrangement according to FIG. 18, the converter I (24) contained in FIG. 18 is blocked. The negative current i mentioned is carried in the arrangement according to FIG. 18 by the converter II (23). If its ignition delay angle αj _| for example the value cti. = 0 °, you get a positive voltage u ^. However, if this ignition delay angle is set to the value α ,, = 180 °, for example, a negative voltage U results. It is therefore possible to reverse both the current and the voltage direction on the DC side of the converter combination according to FIG. 18.

The most important application for practical use is probably the one in which a reversal of the current i is required, but a reversal of the voltage Uς can be dispensed with. The converter combination presented in FIG. 18 can then be simplified in that the main current valves contained in the converter II (23) outlined there are removed and replaced by diodes with the same polarity. The arrangement thus created is shown in FIG. 19. In the converter II (25) shown in FIG. 19, the operating state at 0 ° is therefore always set automatically. Accordingly, the converter I (24), which is connected antiparallel on the DC side, is to be operated with an ignition delay angle of αι «180 °. Of course, in each converter with actively influenced commutation and in every converter combination which contains such a converter, the main flow valves contained therein, blocking in the reverse direction and continuously controllable in the forward direction, are preferably each connected in the same direction by a series connection of one main flow valve which is continuously controllable in the forward direction by an IGBT, and by one diode each.

As an example of this possibility, the converter (13) shown in FIG. 13 is sketched again in FIG. 20, after its total of six RSIGBTs a to f each by means of a series connection of the same polarity, each with an IGBT (26) and a diode ( 27) have been replaced. If the converter (28) created in this way in FIG. 20 is operated with an ignition delay angle α 0 0 °, the diodes (27) contained therein are absolutely necessary to absorb the reverse voltage that arises in the process. If, on the other hand, this converter (28) is always operated with an ignition delay angle α ~ 180 °, the diodes (27) contained therein are not subjected to reverse voltage. Then the diodes (27) can all be bridged and thus eliminated. Such a procedure is possible with all converters according to the invention with actively influenced commutation. Unless the main flow valves contained in such valves, which are continuously controllable in the forward direction, are not subjected to reverse voltage, they also do not have to be lockable in the reverse direction.

The key concept of the invention presented herewith can also be used in the following modified manner. Auxiliary branches are created parallel to the individual main valve branches for the purpose of commutation. This makes it possible to use the mainstream valves, which are already widespread, reverse-blocking and switchable on and off, instead of the main flow valves which are required for a directly actively influenced commutation, which block in the reverse direction and are continuously controllable in the forward direction. An actively influenced commutation then basically takes place using one of the auxiliary branches mentioned, while the main flow valves which block and can be switched on and off in the reverse direction are only switched on and off completely according to their capacities. With this modified use of the key concept according to the invention, the main flow valves contained therein, which block there in the reverse direction and are continuously controllable in the forward direction, are thus removed from the converters which have arisen to date. Given that The main flow valves just mentioned are also to be referred to below briefly as “main flow valves removed”. For each individual "removed main flow valve", a main flow valve that takes its place, is to be blocked, backwards blocking and can be switched on and off is inserted as an alternative. In view of this procedure, the last-mentioned main flow valves are also referred to in the following as "main flow valves inserted as an alternative". These "alternatively inserted main flow valves" are installed in the original arrangement in such a way that they are capable of carrying current in the same direction as those "removed main flow valves", in the place of the "alternatively inserted main flow valves". Furthermore, in parallel to each "alternatively inserted main flow valve", from its current inflow electrode, the so-called anode, to its current drain electrode, the so-called cathode, auxiliary current paths are created which are capable of carrying current in the same direction as those "alternatively inserted main flow valves" to their anodes - Cathode section these auxiliary current paths are connected in parallel. These auxiliary current paths are then equipped with components such that, on the one hand, each of these auxiliary current paths contains the function of a diode path specific to this auxiliary current path and, on the other hand, a modified use of the key concept according to the invention is possible. In practice there are three different ways for this modified use of the key concept according to the invention.

In the first way, in the individual auxiliary current paths there is provided, in each case a multiply used current valve which blocks in the reverse direction and is continuously controllable in the forward direction and which is referred to below as "auxiliary valve (30) blocking in the reverse direction and continuously controllable in the forward direction". This newly created circuit is now operated in such a way that when a main flow valve contained in the original circuit is fully switched on, the "main flow valve that has now been removed" in the now present arrangement is switched on for the "main flow valve replaced as an alternative", and then, when a main flow valve contained in the original circuit is completely switched off, the "main flow valve inserted as an alternative" for this, now "removed main flow valve" in the present arrangement is switched off, and that in that auxiliary flow path, the "main flow valve inserted as an alternative" in parallel is switched, contained "in the reverse direction blocking and continuously controllable in the forward direction auxiliary flow valve (30)" is also turned off. If, between the main current electrodes of one of the main current valves contained in the original circuit, one in Direction of the current flow present or targeted there, positive, constant or variable voltage u _SQ || should be set, this is taken into account in the present arrangement by the fact that that "alternatively inserted main flow valve", which has taken the place of the named "removed main flow valve", is switched off, and that between the main flow electrodes of that auxiliary flow path, of the "main flow valve inserted as an alternative" is connected in parallel and contains "auxiliary flow valve (30) blocking in the backward direction and continuously controllable in the forward direction" in the direction of the current flow present or desired there the voltage u _SQ || is set.

As an example of this first way of using the key concept according to the invention in a modified manner, FIG. 21 shows the arrangement according to FIG. 4, after the RSIGBTs (14) originally contained there, designated by the letters a to f, have been removed and in their place a backward blocking GTO (29) was installed as a "replacement main flow valve". Furthermore, in the arrangement according to FIG. 21, an auxiliary current path was created parallel to each GTO (29), from the anode to its cathode, which is capable of carrying current in the same direction as that of the GTO (29), to its anode-cathode path this auxiliary current path is connected in parallel. In this example, the individual auxiliary current paths each contain a diode (31) specific to each auxiliary current path and a respective auxiliary RSIGBT, which in this case is used several times, which functions as a so-called "auxiliary current valve (30) blocking in the reverse direction and continuously controllable in the forward direction" . As is immediately apparent from the illustration in FIG. 21, in this example it is fundamentally not necessary that the auxiliary RSIGBTs used there actually have to have a blocking capability in the reverse direction. These auxiliary RSIGBTs can therefore be replaced by conventional IGBTs. If, for example, the RSIGBT (14) designated by a is fully switched on in the original circuit according to FIG. 4, the GTO (29) which is also inserted as an alternative and is also labeled a is switched on in the arrangement according to FIG. 21. Conversely, if in the original circuit according to FIG. 4 the RSIGBT (14) designated there with a is switched off, in the arrangement according to FIG. 21 the GTO (29), which is also substituted for it, also designated with a, and that to this alternatively inserted GTO (29) parallel auxiliary RSIGBT switched off. If there is a voltage u _so || between the main current electrodes of one of the RSIGBTs (14) contained in the original circuit in the direction of the current flow that is present there or is aimed for there should be set this is taken into account in the arrangement shown in FIG. 21, in that the alternatively inserted GTO (29), which has taken the place of the aforementioned RSIGBT's (14) removed here, is switched off and that between the main current electrodes of the GTO, which is substituted for this, is switched off (29) Auxiliary RSIGBTs connected in parallel in the direction of the current flow present or desired there the voltage u _so || is set.

In the second way of using the key concept according to the invention in a modified manner, the individual auxiliary current paths provide for a series connection of one voltage sink (32), which may be used several times, and one, optionally multiple use, reverse-blocking and on / off switchable current valve, the latter hereinafter also to be referred to as "backward-blocking auxiliary flow valve (33) that can be switched on and off". This newly created circuit is now operated in such a way that when a main flow valve contained in the original circuit is fully switched on, the "main flow valve that has now been removed" in the now present arrangement is switched on for the "main flow valve replaced as an alternative", and then, when a main flow valve contained in the original circuit is completely switched off, the "main flow valve inserted as an alternative" for this, now "removed main flow valve" in the present arrangement is switched off, and that in that auxiliary flow path, the "main flow valve inserted as an alternative" in parallel is switched, contained "backward blocking and on and off switchable auxiliary flow valve (33)" is also turned off. Insofar as a positive, constant or variable voltage u π is to be set between the main current electrodes of one of the main current valves contained in the original circuit, in the direction of the current flow present or desired there, this is taken into account in the arrangement now present by the fact that the "alternative" inserted main flow valve ", which has taken the place of the present," removed "main flow valve", is switched off, and that the "reverse flow blocking" as well as "on and off" switchable contained in that auxiliary flow path, which is connected in parallel to this "alternatively inserted main flow valve" Auxiliary flow valve (33) "is switched on, and that the current sink used by the current flowing through this" reverse-blocking and switchable and switchable auxiliary flow valve (33) "is set in such a way that at this voltage sink, from a current flowing through it, in its Direction one Voltage with the value un is called up. 22 shows the arrangement according to FIG. 4 as an example of this second way of using the key concept according to the invention in a modified manner, after the RSIGBTs (14) originally contained there, designated by the letters a to f, have been removed and in their place a backward blocking GTO (29) was installed as a "replacement main flow valve". Furthermore, in the arrangement according to FIG. 22, an auxiliary current path was created parallel to each GTO (29), from the anode to its cathode, which is capable of carrying current in the same direction as that of the GTO (29), to its anode-cathode path this auxiliary current path is connected in parallel. In this example, the individual auxiliary current paths each contain a diode (31) specific to each auxiliary current path and in each case a series circuit, in this case used several times, consisting of a Zener diode (32) serving as a voltage sink and an auxiliary GTO which acts as a so-called "reverse" blocking and on and off switchable auxiliary flow valve (33) "functions. As can be seen directly from the illustration in FIG. 22, in this example it is fundamentally not necessary for the auxiliary GTOs used there to have a blocking capability in the reverse direction. If, for example, the RSIGBT (14) designated by a is fully switched on in the original circuit according to FIG. 4, the GTO (29) which is also inserted as an alternative and is also labeled a is switched on in the arrangement according to FIG. 22. Conversely, if in the original circuit according to FIG. 4 the RSIGBT (14) designated there with a is switched off, in the arrangement according to FIG. 22 the GTO (29), which is also inserted as an alternative and is also designated with a, and the one in that Auxiliary current path, which is connected in parallel to this GTO (29), which is inserted as an alternative, the auxiliary GTO contained is switched off. If there is a voltage u || between the main current electrodes of one of the RSIGBTs (14) contained in the original circuit in the direction of the current flow which is present there or is aimed for there 22, this is taken into account in the arrangement shown in FIG. 22 by the fact that the GTO (29), which has been replaced as an alternative and which has taken the place of the RSIGBT (14) which has been removed in the present case, is switched off, and that in that Auxiliary current path, which is connected in parallel to this GTO (29) which is inserted as an alternative, the auxiliary GTO containing is switched on, and that the Zener voltages of the Zener diodes contained in FIG. 22 are chosen to be as large as the aforementioned value u π. Under these circumstances, the arrangement shown in FIG. 22 behaves in the same way as that outlined in FIG. 4, provided the desired commutations are brought about in the latter by means of a constant value of the voltage u π. In the third way of using the key concept according to the invention in a modified manner, the individual auxiliary current paths are provided with a series connection of the primary winding (34) of a transformer (35), which may be used several times, and one, optionally multiple use, reverse-blocking and switchable and disengageable current valve, the latter being also referred to below as "auxiliary valve (33) which blocks and can be switched on and off". The secondary winding (36) of the transformer (35) is connected to a voltage sink via a rectifier circuit (37), the DC voltage side of the converter preferably being used as such. Furthermore, a demagnetizing current path is created in parallel with each of the aforementioned auxiliary current paths or in parallel with each aforementioned series connection from the "reverse-blocking auxiliary current valve (33) that can be switched on and off" and the primary winding (34) of the transformer (35), which leads in the same direction to carry the current capable, like that part of the auxiliary current path which is parallel to this demagnetizing current path. These demagnetization current paths are then equipped with components in such a way that each of these auxiliary current paths contains the function of a diode path specific to this auxiliary current path and that in the individual demagnetization current paths one voltage sink (38), which may be used several times, and one, optionally used several times, are included , reverse blocking and on and off switchable current valve follow one another, the latter being referred to below as "reverse blocking and on and off switchable demagnetizing flow valve (39)". This newly created circuit is now operated in such a way that when a main flow valve contained in the original circuit is fully switched on, the "main flow valve which has now been removed" is switched on in the present arrangement "replacement main flow valve" and then, if a main flow valve contained in the original circuit is completely switched off, the "main flow valve now replaced" is switched off for this now "removed main flow valve" in the now present arrangement. If there is a positive, constant or variable voltage u || between the main current electrodes of one of the main current valves contained in the original circuit, in the direction of the current flow present or sought there To be set, this is taken into account in the present arrangement by switching off that "alternatively inserted main flow valve", which has taken the place of the aforementioned "removed main flow valve", and that in the auxiliary flow path leading to it "alternatively inserted main flow valve" is connected in parallel, contain ne "reverse blocking and on and off switchable auxiliary flow valve (33)" is switched on, and that the transmission ratio of that transformer (35), the primary winding (34) of which by the immediately mentioned "reverse blocking and on and off switchable auxiliary flow valve (33 ) "flowing current is passed through, is chosen so that a voltage which has the value u π is evoked on this primary winding (34) by a current flowing over it in the direction of this current flow. Furthermore, when the current through the auxiliary current path, in which the above-mentioned "backward-blocking and on and off switchable auxiliary flow valve (33)" is contained, has dropped to a value which is in the range of the primary winding (34) of the Transformer (35) related magnetizing current of the transformer (35) lies, the above-mentioned "reverse-blocking and on and off switchable auxiliary flow valve (33)" is switched off again and that "reverse-blocking and on and off switchable demagnetization flow valve (39)" is switched on, which in Parallel path lies to that path which contains the above-mentioned "backward-blocking auxiliary valve (33) which can be switched on and off". The "backward blocking and on and off demagnetization flow valves (39)" are switched off again after a current that has flowed through them has decayed to zero.

As an example of this third way of using the key concept according to the invention in a modified manner, FIG. 23 shows the arrangement according to FIG. 4 after the RSIGBTs (14) originally contained there, designated by the letters a to f, have been removed and in their place a backward blocking GTO (29) was installed as a "replacement main flow valve". Furthermore, in the arrangement according to FIG. 23, an auxiliary current path was created parallel to each GTO (29), from the anode to its cathode, which is capable of carrying current in the same direction as that of the GTO (29), to its anode-cathode path this auxiliary current path is connected in parallel. In this example, the individual auxiliary current paths each contain a diode (31) specific to each auxiliary current path and in each case a series connection, which in this case is used several times, comprising the primary winding (34) of a transformer (35) and an auxiliary GTO, which is known as a " Auxiliary valve (33) "which locks backwards and can be switched on and off." Furthermore, in the arrangement according to FIG. 23, a demagnetizing current path was created in parallel with each series connection of the primary winding (34) of a transformer (35) and an auxiliary GTO, which is capable of carrying current in the same direction as that part of the auxiliary current path which this demagnetization current path is connected in parallel. In In this example, the individual demagnetization current paths each contain a series circuit consisting of a Zener diode (38) serving as a voltage sink and a demagnetization GTO, which functions as a so-called "reverse-blocking and demagnetization current valve (39)" which can be switched on and off. As can be seen directly from the illustration in FIG. 23, it is basically not necessary in this example that the auxiliary GTOs and demagnetizing GTOs used there have to have a blocking capability in the reverse direction. If, for example, the RSIGBT (14) denoted by a is fully switched on in the original circuit according to FIG. 4, the GTO (29) which is also inserted as a substitute and is also denoted by a is switched on in the arrangement according to FIG. 23. Conversely, if in the original circuit according to FIG. 4 the RSIGBT (14) designated there a is switched off, in the arrangement according to FIG. 23 the GTO (29) which is also inserted as an alternative and is also designated a is switched off. If there is a voltage u _so | between the main current electrodes of one of the RSIGBTs (14) contained in the original circuit in the direction of the current flow which is present there or which is intended there 23, this is taken into account in the arrangement shown in FIG. 23 by switching off that GTO (29) which has been replaced as an alternative and which has taken the place of the RSIGBT's (14) which have been removed in the present case, and that in that auxiliary current path, which is connected in parallel to this alternatively inserted GTO (29), the auxiliary GTO contained is switched on, and that the transformation ratio of the transformers (35) contained in FIG. 23 is chosen so large that at its primary winding (34) of a current flowing over them, in the direction of this current flow, a voltage is raised which has the value u _so π. Furthermore, when the current through the auxiliary current path, in which the above-mentioned auxiliary GTO is contained, has dropped to a value which is in the range of the magnetizing current of the transformer (35) related to the primary winding (34) of the transformer (35) ), the above-mentioned auxiliary GTO is switched off again and that demagnetizing GTO is switched on, which lies in the parallel path to the aforementioned series connection of the primary winding (34) of a transformer (35) and an auxiliary GTO. The demagnetizing GTOs are switched off again after a current that has flowed through them has decayed to zero. Under these circumstances, the arrangement shown in FIG. 23 behaves the same as that outlined in FIG. 4, provided the desired commutations are brought about in the latter by means of a constant value of the voltage u M. Of course, if the key concept of the invention presented herewith is used in the modified manner described above, the reverse-blocking main flow valves which can then be switched on and off can then be removed and in each case by means of a series connection with the same polarity connected to a main flow valve which can be switched on and off to be replaced by a diode. Furthermore, the auxiliary flow valves (30) which may be contained therein and which can be "blocked in the reverse direction and continuously controllable in the forward direction" can be removed and replaced in each case by a series connection of the same polarity in each case with a current valve which can be controlled continuously in the forward direction and a diode in each case. Likewise, the "backward-locking auxiliary flow valves (33)" which can be switched on and off can be removed and replaced by a series connection of a current valve that can be switched on and off and a diode in each case. Likewise, the "backward-blocking demagnetization current valve (39)" which may be contained therein and which can be switched on and off can be removed and replaced in each case by a series connection of the same polarity, each with a current valve which can be switched on and off and with a diode in each case. Finally, those of the diodes contained therein, which are not stressed with reverse voltage during the intended use, may then all be bridged and thus eliminated themselves.

Claims

P A T E N T A N S P R U C H E

. Power converter that can be connected to an alternating or three-phase voltage system, preferably designed in a bridge circuit, with current valves between which a current can be commutated due to commutation voltages that occur, the commutation voltage when the current is commutated between valves having current inflow electrodes and current outflow electrodes, the current inflow electrodes of which are coupled together to form a collection point, by at least one current path, in which a positive voltage is built up between the collection point of the current inflow electrodes and one of the current outflow electrodes of the valves coupled together at their current inflow electrodes, can be adjusted in such a way that the commutation of the current between the current valves can be achieved at permissible commutation voltages, and / or the Commutation voltage during a commutation of the current between valves having current inflow electrodes and current outflow electrodes, the current outflow electrodes of which are coupled together to form a collection point, by at least one current path in which a negative voltage is built up between the collection point of the current outflow electrodes and one of the current inflow electrodes of the valves coupled together at their current outflow electrodes, in such a way can be set so that the commutation of the current between the current valves can be achieved at permissible commutation voltages.

2. Power converter connected to an alternating or three-phase voltage system, preferably designed in a bridge circuit, with actively influenced commutation, characterized in that its main flow valves block in the reverse direction and are continuously controllable in the forward direction, and that when the power supply is switched on after switching on certain valve, the commutation voltage effective in the commutation circuit from the previously current-carrying valve to the valve subsequently intended for current conduction would become impermissibly large in view of the AC-side reactions caused by it, by influencing the control path of the valve subsequently intended for current conduction between its main current electrodes, in the direction of the desired Current flow positive, constant or variable, possibly also current-dependent voltage is set, which is so large that the now in the commutation circuit from the previously current-carrying valve to the subsequent The effective commutation voltage for the current-carrying valve becomes small enough that the AC-side reactions caused by it are permissible.

Power converter with actively influenced commutation according to claim 2, characterized in that the valve which, in the course of said commutation, has transferred the current conduction from the previously current-carrying valve to the valve subsequently intended for current conduction, during its subsequent blocking period, which lasts until it is next switched on again, by a Influencing its control path, it is put into its blocking state at least to such an extent and kept there that it can withstand its further voltage stress in the forward direction when it is fully switched off, and that the valve which, in the course of the mentioned commutation, moves from the previously current-carrying valve to the valve subsequently intended for current-carrying has taken over current conduction, during its subsequent conduction period, which lasts until the start of its next current output, by influencing its control path, it is brought into its conductive state at least to such an extent and kept there that it can withstand its further current load in the forward direction when fully switched on.

Power converter connected to an alternating or three-phase voltage system, preferably designed in a bridge circuit, with actively influenced commutation, characterized in that its main flow valves block in the reverse direction and can be continuously controlled in the forward direction, and that when the valve subsequently intended for current conduction is switched on the commutation voltage effective in the commutation circuit from the previously current-carrying valve to the valve subsequently intended for current conduction is too small for successful commutation, by influencing the control path of the previously current-carrying valve between its main current electrodes, a positive, constant or variable, if necessary, in the direction of the existing current flow current-dependent voltage is set, which on the one hand is large enough that the desired commutation from the previously current-carrying valve to the valve subsequently intended for current-carrying is now successfully carried out, and on the other hand is only so large that the commutation circuit from the previously current-carrying valve is now carried out successfully Valve for subsequent power supply The commutation voltage effective for a certain valve remains small enough that the AC side effects caused by it are permissible.

5. Power converter with actively influenced commutation according to claim 4, characterized in that the valve which, in the course of said commutation, from the previously current-carrying valve to the valve subsequently intended for current conduction has given off the current conduction, during its subsequent locking period, which lasts until it is next switched on again by influencing its control path, it is kept in its blocking state at least to such an extent that it can withstand its further voltage stress in the forward direction when fully switched off, and that the valve which, in the course of the mentioned commutation from the previously current-carrying valve to the valve subsequently intended for current-carrying, carries out the current has taken over, during its subsequent conduction period, which lasts until the start of its next current output, is kept in its conductive state at least to such an extent by influencing its control path that it can withstand its further current load in the forward direction when fully switched on.

6. Power converter with actively influenced commutation according to one of claims 2 or 3 and one of claims 4 or 5, characterized in that, depending on the application requirements, this power converter either has one of the operating modes described in claims 2 and 3 or one of those described in the claims 4 and 5 makes use of the operating methods described.

7. Power converter with actively influenced commutation according to one of claims 2 or 3 and one of claims 4 or 5, characterized in that this power converter is operated during one and the same commutation processes both by one of the operating modes described in claims 2 and 3 and by one of the makes use of the operating modes described in claims 4 and 5.

8. Combination of at least a first, bridge-connected power converter according to claims 2 to 7 and at least a second, bridge-connected power converter according to one of claims 2 to 7, which are connected together to the the same AC or three-phase voltage system are connected and are connected in anti-parallel on their respective DC voltage sides.

9. Combination of at least a first, bridge-connected power converter according to claim 4 or 5 and a second, bridge-connected diode power converter (25), which are connected together to the same AC or three-phase voltage system and are connected in anti-parallel on their respective DC voltage sides.

10. Power converter with actively influenced commutation according to one of claims 2 to 7 or power converter combination according to one of claims 8 or 9, characterized in that the main flow valves contained therein, which block in the reverse direction and can be continuously controlled in the forward direction, are removed and each replaced by a series connection with the same polarity a main flow valve (26) that can be continuously controlled in the forward direction and are replaced by a diode (27).

1 1 . Power converter or power converter combination according to claim 10, characterized in that the diodes (27) contained therein, which are not subjected to reverse voltage during intended use, are bridged and are therefore unnecessary.

12. Power converter with actively influenced commutation according to one of claims 2 to 7, or power converter combination according to one of claims 8 or 9, characterized in that the main flow valves contained therein, which block in the reverse direction and can be continuously controlled in the forward direction, are removed and, in view of this, also briefly below are referred to as "removed main flow valves", and that for each individual one of these "removed main flow valves", a main flow valve that takes its place, is reverse-locking and can be switched on and off is inserted as a replacement, which in view of this is also referred to below as a "replacement main flow valve ( 29)" is referred to, and that the "replacement main flow valves (29)" are capable of conducting current in the same direction as those "removed main flow valves", which are replaced by the "replacement main flow valves (29)", that parallel to each "substitute main flow valve (29)", from its current inflow electrode, the so-called anode, to its current outflow electrode, the so-called cathode, an auxiliary current path is created, which is capable of carrying current in the same direction as that "substitute main flow valve (29)", to whose anode-cathode path this auxiliary current path is parallel, that each of these auxiliary current paths contains the function of a diode path that specifically belongs to this auxiliary current path, and that in each of the individual auxiliary current paths there is one, if necessary multiple times, blocking in the reverse direction and there is a flow valve that can be continuously controlled in the forward direction, which is hereinafter referred to as "an auxiliary flow valve (30) that blocks in the reverse direction and can be continuously controlled in the forward direction", so that when a main flow valve contained in the original circuit according to one of claims 2 to 9 is fully switched on, the "replaced main flow valve (29)" is switched on for this, now "removed main flow valve" in the present arrangement, so that when a main flow valve contained in the original circuit according to one of claims 2 to 9 is completely switched off, the for this , now "removed main flow valve" in the current arrangement "replacement inserted main flow valve (29)" is switched off, and that in that auxiliary current path that is parallel to this "replacement inserted main flow valve (29)" contained "blocking in the reverse direction and in The auxiliary flow valve (30), which can be continuously controlled in the forward direction, is also completely switched off, and that when there is a positive flow between the main current electrodes of one of the main flow valves contained in the original circuit according to one of claims 2 to 9, in the direction of the current flow present there or desired there, constant or variable, possibly also current-dependent voltage u || is to be set, this is taken into account in the current arrangement in that the "substitute main flow valve (29)", which has taken the place of the mentioned, here "removed main flow valve", is switched off and between the main current electrodes in that auxiliary current path , which lies parallel to this "substitute main flow valve (29)", contains "auxiliary flow valve (30) which blocks in the reverse direction and can be continuously controlled in the forward direction" in the direction of the The voltage u π is set based on the current flow present there or desired there.

13. Power converter with actively influenced commutation according to one of claims 2 to 7, or power converter combination according to one of claims 8 or 9, characterized in that the main flow valves contained therein, which block in the reverse direction and can be continuously controlled in the forward direction, are removed and, in view of this, also briefly below are referred to as "removed main flow valves", and that for each individual one of these "removed main flow valves", a main flow valve that takes its place, is reverse-locking and can be switched on and off is inserted as a replacement, which in view of this is also referred to below as a "replacement main flow valve ( 29)" and that the "replacement main flow valves (29)" are capable of conducting current in the same direction as those "removed main flow valves", which are replaced by the "replacement main flow valves (29)" that are parallel to each ""substitute inserted main current valve (29)", from the current inflow electrode, the so-called anode, to the current outflow electrode, the so-called cathode, an auxiliary current path is created, which is capable of carrying current in the same direction as that "substitute inserted main current valve (29)", This auxiliary current path is parallel to the anode-cathode path, that each of these auxiliary current paths contains the function of a diode path that specifically belongs to this auxiliary current path, and that in each of the individual auxiliary current paths there is one voltage sink (32), possibly used several times, and one, if necessary multiple-used, reverse-locking and switchable on/off flow valves follow one another, the latter also being referred to below as a "backward-locking and on/off-switchable auxiliary flow valve (33)", that when one in the original circuit according to one of claims 2 The main flow valve contained in 9 to 9 is fully switched on, which is switched on for this, now "removed main flow valve" in the current arrangement "substitute inserted main flow valve (29)", that when a main flow valve contained in the original circuit according to one of claims 2 to 9 is completely switched off, the "main flow valve (29) inserted as a replacement" for this, now "removed main flow valve" in the present arrangement is switched off, and that in that auxiliary current path that is parallel to this "main current valve (29) inserted as a replacement", the "backward blocking and switchable on and off auxiliary current valve (33)" contained in it is also switched off, and that when between the main current electrodes of one of the in the original Circuit according to one of claims 2 to 9, main flow valves contain a positive, constant or variable, possibly also current-dependent voltage u || in the direction of the current flow present there or desired there is to be set, this is taken into account in the present arrangement by the fact that the "main flow valve (29) inserted as a replacement", which has taken the place of the mentioned, here "removed main flow valve", is switched off, and that in that auxiliary current path, the "reverse-locking and switchable auxiliary flow valve (33)" contained in it is switched on, and that the "reverse-locking and switchable auxiliary flow valve (33) which can be switched on and off" is switched on. "The voltage sink (32) used by the current flowing is set in such a way that a voltage which has the value u π is created at this voltage sink (32) by a current flowing over it, in the direction of this current flow.

14. Power converter with actively influenced commutation according to one of claims 2 to 7, or power converter combination according to one of claims 8 or 9, characterized in that the main flow valves contained therein, which block in the reverse direction and can be continuously controlled in the forward direction, are removed and, in view of this, also briefly below are referred to as "removed main flow valves", and that for each individual one of these "removed main flow valves", a main flow valve that takes its place, is reverse-locking and can be switched on and off is inserted as a replacement, which in view of this is also referred to below as a "replacement main flow valve ( 29)" and that the "substitute main flow valves (29)" are capable of conducting current in the same direction as those "removed main flow valves". valves", which are replaced by the "substitute main flow valves (29)", so that an auxiliary current path is created parallel to each "substitute main flow valve (29)", from its current inflow electrode, the so-called anode, to its current outflow electrode, the so-called cathode is capable of carrying current in the same direction as the "substitute main current valve (29)", to whose anode-cathode path this auxiliary current path is parallel, that each of these auxiliary current paths contains the function of a diode path specifically belonging to this auxiliary current path, and that the individual auxiliary current paths each contain a series circuit in which a reverse-blocking and switchable on/off current valve, which can be used multiple times, is also referred to below as a "reverse-blocking and on/off-switchable auxiliary flow valve (33)", and the primary winding (34), which may be used several times, of a transformer (35) follow one another, and that the secondary winding (36) of the transformer (35) is connected to a voltage sink via a rectifier circuit (37), as such preferably the DC voltage side of the converter it is used that a demagnetization current path is created in parallel to each of the aforementioned auxiliary current paths or in parallel to each of the aforementioned series connections from the "reverse blocking and switchable on and off auxiliary current valve (33)" and the primary winding (34) of the transformer (35), which runs in the same direction is capable of carrying current, like that part of the auxiliary current path that is parallel to this demagnetization current path, that each of these demagnetization current paths contains the function of a diode path that specifically belongs to this demagnetization current path, and that in each of the individual demagnetization current paths there is a voltage sink, possibly used several times ( 38) and one, possibly used multiple times, reverse-locking and switchable on/off flow valve follow one another, the latter also being referred to below as a "backward-locking and switchable on/off demagnetization flow valve (39)" that when one in the Original circuit according to one of claims 2 to 9 contained main flow valve is fully switched on, which is now used for this "removed main flow valve" in the current arrangement "substitute inserted main flow valve (29)" is switched on, so that when a main flow valve contained in the original circuit according to one of claims 2 to 9 is completely switched off, the main flow valve for this, now "removed main flow valve "In the present arrangement, the "substitute main flow valve (29)" is switched off, so that when between the main current electrodes of one of the main flow valves contained in the original circuit according to one of claims 2 to 9, there is a main flow valve in the direction of the existing or desired there Current flow positive, constant or variable, if necessary also current-dependent voltage u π is to be set, this is taken into account in the current arrangement by the fact that the "main flow valve (29) inserted as a replacement" takes the place of the mentioned, now "removed main flow valve" has occurred, is switched off, and that the "backward-blocking and switchable on and off auxiliary current valve (33)" contained in that auxiliary current path which is parallel to this "main current valve (29) inserted as a replacement" is switched on, and that the transmission ratio of that transformer (35), the primary winding (34) of which is traversed by the current flowing through the immediately above-mentioned "reverse-blocking and on-off-switchable auxiliary flow valve (33)", is chosen so that this primary winding (34) has a current flowing over it Current, in the direction of this current flow, a voltage is created which has the value u π, so that when the current flows through the auxiliary current path, in which the above-mentioned "reverse blocking and switchable auxiliary current valve (33)" is contained, has dropped to a value which is in the range of the magnetizing current of the transformer (35) related to the primary winding (34) of the transformer (35), the above-mentioned "backward-blocking and switchable auxiliary current valve (33)" is switched off again and that "reverse locking and switchable demagnetization flow valve (39)" is switched on, which lies in the parallel path to the path that contains the above-mentioned "backward locking and switchable on and off auxiliary flow valve (33)", and that the "reverse locking" valves used as well as demagnetization current valves (39) which can be switched on and off" are each switched off again after a current that previously flowed through them has decayed to zero.

5. Power converter or power converter combination according to claim 12, characterized in that the reverse-locking main power valves contained therein which can be switched on and off are removed and each replaced by a series connection with the same polarity of a main power valve that can be switched on and off and a diode each, and that the "auxiliary flow valves (30)" contained therein, which are blocked in the reverse direction and continuously controllable in the forward direction, are removed and each replaced by a series connection with the same polarity, each with a flow valve that can be continuously controlled in the forward direction and a diode each.

6. Power converter or power converter combination according to claim 1 3, characterized in that the reverse-locking main power valves contained therein which can be switched on and off are removed and each replaced by a series connection with the same polarity of a main power valve that can be switched on and off and a diode each, that the "reverse locking and switchable on/off auxiliary power valves (33)" contained therein are removed and replaced by a series connection with the same polarity, each with a power valve that can be switched on and off and a diode each.

7. Power converter or power converter combination according to claim 14, characterized in that the reverse-locking main power valves contained therein that can be switched on and off are removed and each replaced by a series connection with the same polarity of a main power valve that can be switched on and off and a diode each, that the "reverse locking and switchable on and off auxiliary current valves (33)" contained there are removed and each replaced by a series connection with the same polarity of a current valve that can be switched on and off and a diode each, and that the "reverse blocking" contained there as well as demagnetization current valves (39) that can be switched on and off and are each replaced by one in the same direction Polarized series connection is replaced by a current valve that can be switched on and off and by a diode.

18. Power converter or power converter combination according to one of claims 15, 16 or 1 7, characterized in that those of the diodes contained therein which are not subjected to reverse voltage during the intended use are bridged and are therefore dispensable.