FR2668663A1 - IMPROVED CUTTING POWER SUPPLY OF THE DIRECT CONDUCTION TYPE. - Google Patents

Abstract

The device comprises two input terminals for a substantially direct voltage source, a transformer having a primary and a secondary, a control stage comprising a controllable switching unit capable of sequentially connecting, according to a predetermined control law, the primary to the two input terminals, and an output stage comprising a downstream rectifier cell connected to the secondary of the transformer, followed by a downstream filtering cell comprising a downstream inductive circuit having a chosen inductive value as well as a downstream capacitance contributing to supply an output voltage. The downstream inductive circuit comprises two downstream inductors (LA1-2, LA2-2) having respective inductive values whose sum is substantially equal to said chosen inductive value, and the two downstream inductors are respectively connected, in series with the downstream capacitor ( CA-2), on either side of this downstream capacity.

Description

M 2668663

  The invention relates to switching power supplies of the direct conduction type.

  Among the switching power supplies, the skilled person

  usually heads of the reverse conduction type

  with an isolated inductive storage circuit ("fly-

  back ") and those of the direct conduction type having

  an isolated serial assembly ("forward").

  The latter type of feeding includes

  two input terminals for a sensitive voltage source -

  continuous, a transformer having a primary and a secondary, a control stage comprising a controllable switching unit, capable of connecting sequentially according to a predetermined control law, the primary to the two input terminals, and an output stage comprising a downstream rectification cell connected to the transformer secondary, followed by a downstream filter cell comprising an inductive circuit

  downstream having a chosen inductive value as well as a capacity

  downstream tee helping to provide an output voltage.

  Compared to reverse conduction power supplies, of which

  those skilled in the art know that the transmitted power is limited

  ted by the very structure of their mounting, the power supplies

  Direct conduction tions have the advantage of not presenting, at least in theory, an upper limit for

  the power transmitted through the transformer.

  In addition, when the control stage comprises a pulse width modulation circuit associated with regulation means, such a supply has the advantage of providing a stable output voltage whatever the variations of the current absorbed by a load connected at output and whatever the variations in input voltage. Such a supply is commonly used with a transformer having a ratio of the number of turns from secondary to primary very significantly less than 1 to produce a low voltage. This is particularly the case in avionics where this type of supply makes it possible to obtain, at from the airplane three-phase network (220 volts RMS between phases), a supply voltage of the order of a few

tens of volts.

  However, when it is desired to use such a feed,

  tion as a voltage booster, in particular to contribute to supplying high voltage, it is then necessary to increase the number of turns in the secondary, and to increase the size of the downstream inductive circuit Consequently, the stray capacitance of the secondary and that of the downstream inductive circuit become significant and are moreover "seen" in the primary through the square of the ratio of the numbers of turns which can then be much greater than 1 The skilled person then knows that the power transmitted through the transformer to each cutting cycle will actually be used to charge this stray capacitance instead of being transmitted at the output of the power supply. A solution could then consist in reducing the switching frequency so as to obtain -cycles whose duration

  larger would allow, after charging this capa-

  parasitic city, the transmission of the remaining power.

  However, in addition to the power losses caused, such a solution would then increase the size of the primary, and therefore the size of the secondary as well.

  that the size of the downstream inductive circuit without obtaining

  to achieve significantly more satisfactory results, and

  this with a larger overall size which can be

  prohibitive in certain applications.

  Faced with such problems, the skilled person has until pre-

  feels abandoned the principle of the use of such ali-

  direct conduction switching statements to contribute

  the generation of a high output voltage.

  The invention aims to provide a solution to these problems.

  It goes against preconceived ideas and proposes a switching power supply of the direct conduction type whose original structure allows its use in voltage booster, in particular to contribute to the generation of a

  high output voltage, with the additional possibility of

  read a high switching frequency.

  The general structure of the switching power supply proposed

  is of the type mentioned above.

  According to the main characteristic of the invention, the circuit

  cooked downstream inductive has two downstream inductors having

  respective inductive values the sum of which is significant

  definitely equal to the inductive value chosen for the circuit

  inductive downstream; these two downstream inductors are then respec-

  connected, in series with the downstream capacity, of

  on either side of this downstream capacity.

  The Applicant then observed that such a structure

  tribute to provide a solution to the problem posed She also observed that such a structure also made it possible to improve the operation of the power supply when it is used as a step-down

to provide low voltage.

  It is also particularly advantageous for the two downstream inductors to be coupled on the same core.

  while being of opposite polarities.

  According to another embodiment, it is provided that the output stage comprises at least one auxiliary rectifying cell functionally analogous to the downstream rectifying cell followed by an auxiliary filtering cell structurally similar to said downstream filtering cell. auxiliary rectification is then connected in parallel with the downstream rectification cell (CR-3) via a capacitive link circuit (CL-3), while the auxiliary capacity of the auxiliary filter cell is connected in series with

  the downstream capacity of the downstream filter cell.

  Other advantages and characteristics of the invention appear

  will be examined on examination of the detailed description below

  and attached drawings, in which: FIG. 1 represents a schematic diagram of a

  direct conduction switching power supply of prior art

laughing,

  Figure 2 shows an embodiment of a

  switching mode according to the invention, FIG. 3 illustrates another embodiment of a switching power supply according to the invention, and FIG. 4 illustrates a third embodiment of a switching power supply according to the invention allowing

  in particular the feeding of a microwave tube.

  The drawings essentially contain elements of a certain character As such, they are an integral part

  of the description and will not only be able to serve better

  explain the detailed description below, but

  also, if necessary, contribute to the definition of the information

  vention. In FIG. 1, the references B El-1 and BE 2-1 designate two input terminals of this device of the prior art,

  for a substantially continuous input voltage source.

  The TR-1 transformer has an EP-1 primary winding

  can be connected to the two input terminals, sequenced

  tially according to a predetermined control law, by a controllable switching unit COM-1 forming part

an ETC-1 control stage.

  There is also provided, downstream of the transformer TR-1, an output stage ETS-1 suitable for delivering a voltage of

  output This output stage includes a rectifier cell

  downstream CR-1, connected to the secondary winding ES-1

  of the transformer, this rectification cell being followed

  life of a CFA-1 downstream filter cell comprising a

  inductance C Il-1 having an inductive value chosen in function

  tion of the application as well as a downstream capacity CA-1, the two terminals B Sl-l and B 52-2 of which define the two

device output terminals.

  The CR-1 rectification cell is here a functional cell

  operating in mono-alternation and comprising two diodes Dl-l and D 2-1, the respective cathodes of which are connected together

  to the terminal of the CIA-1 inductor opposite to that of the B 52-1 re-

  linked to the capacitance CA-1 The anodes of these two diodes are respectively connected to the two terminals of the secondary winding ES-1. Finally, it should be noted, as is usually the case in this type of device of the prior art, that one of the ends of the winding, namely that connected to the terminal BS-1, is connected to the mass, thus constituting

  a "cold" point while the other end of the winding -

This is a "hot" point.

  A person skilled in the art knows that the secondary winding of the transformer ES-1 and the downstream inductance CIA-1 have respective parasitic capacities which can be

  consider, in operation, to be in parallel.

  Their values are therefore added. This resulting capacity Cr then behaves, reduced to primary, as a capacity whose value is equal to Cr (n 2%) 2 o N 2 denotes neither the number of turns of the secondary and neither the number of primary turns When such a device operates in step-down, for example to provide an output voltage of the order of a few tens of volts from an input voltage of the order of 220 volts, in particular with ratios of turns N 2 of the order of 1/15 th to 1/30 th, the resulting capacity reduced to the primary can be neglected On the other hand, in the case where it is desired to operate this device in voltage booster, that is to say to provide an output voltage greater than the input voltage, the ratio N 2 can then become significantly greater than 1 and the value of this resulting stray capacitance reduced to the primary can no longer be neglected. , at each cutting cycle, l the power available at the input of the device will be used to charge this parasitic capacity, the latter being discharged in the following cycle The higher the switching frequency, the shorter the duration of each cycle and the closer the charging time of this capacity the total duration of a cycle Those skilled in the art then understand that the power transmitted at the output of the device can,

  in some cases be very small.

  One solution could then be to decrease the frequency

  this cutting to increase the duration of each cycle so that the load time of the stray capacitance

  occupies only a small portion of the total cycle time.

  However, this would then lead to an increase in the number-

  number of turns in secondary and primary transformer

  and also to an increase in the number of turns of the in-

  downstream ductance CIA-l As a result, the parasitic capacitance at the secondary level would be increased and, ultimately, the result obtained would not be more satisfactory than that indicated in the previous case with a frequency

high cutting.

  At most, this would have led to congestion in the provision

more important.

  While faced with these problems, those skilled in the art have so far abandoned the principle of using a switching power supply of the direct conduction type, the Applicant, on the contrary, proposes a switching power supply of this type whose original structure remedies to the aforementioned drawbacks. An embodiment of such a switching power supply

is illustrated in figure 2.

  In this figure, the downstream inductive circuit of the downstream filter cell CFA-2 now includes two inductors

  downstream L Al-2 and LA 2-2 having respective inductive values

  whose sum is substantially equal to the in-

  ductive chosen for this downstream inductive circuit Preferably

  this, two identical downstream inductors will be chosen These two downstream inductors are then respectively connected, in series with the downstream capacitance CA-2, on either side of this downstream capacitance The terminals of these two inductors, opposite to those connected to the two terminals of the downstream capacity CA-2, are respectively connected, via the rectification cell CR-2 to the two ends of

the secondary winding ES-2.

  It should then be noted that such an arrangement makes it necessary to no longer connect one of the ends of the secondary winding to ground and to consider the two ends.

  of this secondary winding as having a potential flow-

  so again, the Applicant went against a preconceived idea consisting in generally connecting one

  of the ends of the secondary winding to ground.

  The COM-2 controllable switching unit in the control stage

  ETC-2 upstream demand can be achieved in a half-bridge assembly or in a full bridge assembly well known to those skilled in the art A half-bridge assembly is generally illustrated here, generally comprising two transistors mounted as inverters L ' COM-2 switching unit connects the

  two ends of the primary winding EP-2 of the transformer

  mater at the two input terminals B El-2 and BE 2-2 specific to

  receive the input voltage V + and V- respectively.

  In operation, alternately positive and negative voltage slots will be transmitted, through the core

  magnetic transformer NY-2, to secondary winding

  re ES-2 By construction, the person skilled in the art will then understand that the midpoint of the secondary winding ES-2 here constitutes a "cold" point with respect to alternately positive and negative voltage slots while the two ends of the secondary winding constitute

  "hot" spots In other words, a measurement of

  sion carried out at this midpoint O would lead to the value of the DC component of the alternating voltage delivered across the terminals of the secondary winding This midpoint could, moreover possibly, although this is not

  not necessary, be grounded.

  io Therefore, although the parasitic capacity resulting in the secondary is identical to that of the device of the art

  anterior, this is "seen" here in the primary of the transforma-

  no longer through N 2 turns but N 2/2 turns As a result, the parasitic capacity reduced to the primary is divided by four compared to the parasitic capacity of the device of the prior art, since the square intervenes

of the ratio of the number of turns.

  The Applicant has observed that this original arrangement of the

  secondary of the transformer allowed to use a

  direct conduction switching rating in voltage booster while avoiding capacity problems

  parasite She also observed that this original assembly

  nal was also useful when such a power supply was used as a step-down in the sense that a reduction in noise and

common mode output.

  The Applicant also observed that it was still

  possible to reduce the parasitic capacity reduced to the primary

  re, by coupling the two downstream inductors LA 1-2 and LA 2-2.

  This coupling is carried out by winding these two inductors on the same magnetic core, taking care of course of their directions of connection so that they have respective opposite polarities with respect to the direction of passage of the magnetic flux. These two inductors then have

  together, vis-à-vis the external environment, a capa-

  parasitic city equal to that of an inductance taken isolated-

  We therefore obtain a further reduction in the capa-

  resulting parasite in secondary school and therefore

  a reduction in this capacity brought back to primary.

  Although a single-wave rectifier cell has been described here, the particular arrangement of the filter cell of this switching power supply is compatible with other types of rectifier cells, in particular full-wave rectifier cells such as those

  mounted in Graetz Bridge, as illustrated in Figure 3.

  The components of this figure have references

  suffixed with 3 We will only describe here the differences

these between Figures 2 and 3.

  The Graetz bridge CR-3 conventionally comprises two pairs of diodes Dl- 3, D 2-3, D 3-3, D 4-3 The two diodes of each pair are connected in series in the same direction The common terminal of the two diodes (Dl-3 and D 2-3) of one of the pairs forms a first output terminal of the bridge, while the common terminal of the two other diodes of the other pair (D 3- 3 and D 4-3 ) forms the second output terminal The two input terminals are formed by the respective cathodes of two diodes of two different pairs (D 2-3 and D 3-3) as well as by the respective anodes of the two other diodes (Dl- 3

and D 4-3).

  The two bridge input terminals are respectively connected to the two ends of the secondary winding while

  the two output terminals are connected to the two res-

  pectives of the two downstream inductors LA 1-3 and LA 2-3, opposite

  to those connected to CI-3 downstream capacity.

  It is then expected that the output stage comprises, of a

  in general, at least one auxiliary rectification unit

  CRX-3 linker functionally analogous to the CR-3 downstream rectification cell, followed by a CFAX-3 auxiliary filter cell structurally analogous to the cell

CFA-3 downstream filtering.

  The auxiliary rectifier cell is functionally analogous to the downstream rectifier cell in the sense that its operating mode (single-alternation or bi-alternation for example) will be identical to that of the downstream rectifier cell In practice, as illustrated here , the auxiliary rectifier unit is also

  structurally similar to the downstream rectification unit.

  The Graetz bridge (Dl X-3, D 2 X-3, D 3 X-3, D 4 X-3) forming this auxiliary rectifier cell CRX-3 is connected in parallel with the Graetz bridge of the cell downstream rectification CR-3 by a capacitive link circuit CL-3 Concretely, this capacitive link circuit comprises two link capacitors CL-3 respectively connected between the two homologous input terminals of these two bridges

from Graetz.

  As already explained above, it is particularly advantageous

  tageux that the two downstream inductors LA 1-3 and LA 2-3, as well as the two downstream auxiliary inductors LAX 1-3 and LAX 2-3 are coupled together, that is to say wound on the same magnetic core NYL -3 For clarification purposes, the inductances of the same polarity are shown in solid lines with a solid circle indicating the direction of polarization, and the inductances of opposite polarities in dashed lines with an empty dashed line. in the sense of connection of these inductors so as to respect their respective polarity Thus, in particular,

  the two inductors LA 1-3 and LAX 2-3 of the filter cells

  downstream CFA-3 and auxiliary CFAX-3, connected to the common terminal of the downstream capacities CA-3 and CAX-3 are of opposite polarity. In practice, the winding of these inductors on the NYL-3 magnetic core is carried out by first winding one

  on the other all the inductances of a polarity, for example-

  ple those shown in dashed lines, then all inductants

those of opposite polarity.

  The parasitic capacitance of all these downstream and auxiliary inductors

  coupled linkers is then equivalent to the parasitic capacity

  te of a single inductance taken in isolation.

  Those skilled in the art will understand that the assembly thus produced

  transformer secondary is actually a double

  voltage blocker In fact, in operation, the VSA-3 voltage delivered between the two terminals B 51-3 and B 52-3 of the downstream capacity CA-3 is of a level similar to that of the VSAX-3 voltage delivered between the terminals B 52-3 and B 53-3 of the CAX-3 auxiliary capacity Of course, as already explained, the parasitic capacity resulting from the secondary is always seen through half the number of turns

of this secondary winding.

  However, although the nominal levels of the output voltages are equal, the power delivered between the terminals

  downstream capacity CA-3 is greater than that deli-

  vrée between the terminals of the auxiliary capacity CAX-3 In other words, if such a supply is intended to supply two loads connected respectively to the terminals

  downstream capacity CA-3 and across the auxiliary capacity

  CAX-3 link, we preferentially have at the terminals of the downstream capacity CA-3 the charge likely to require

  the fastest power call.

  Of course, an output voltage can be taken between two of the three terminals B 51-3, B 52-3 and B 53-3, and in particular between the two extreme terminals of the two downstream and auxiliary capacities. exit which is

  the sum of the two voltages VSA-3 and VSAX-3.

  Such an embodiment can be generalized by connecting

  in parallel a plurality of auxiliary rectification cells

  laires linked mutually by link capacities, these auxiliary cells being all followed by auxiliary filter cells of similar structure, all the CAX auxiliary capacities forming with the downstream capacity

  CA a row of capacities connected in series.

  The output stage can also be generalized as illustrated in the embodiment of FIG. 4, particularly well suited to the supply of a TOP microwave tube,

  especially for a pulse radar.

  In this figure, the references of the various constituents are this time assigned the suffix 4 We will not describe

  that the differences between this figure 4 and figure 3.

  Although the DC input voltage V +, V can be

  developed from a suitable DC voltage source

  tional, we will assume here, as it is generally the

  case on board an aircraft, that this input voltage is

  from a three-phase network and suitably rectified by

  a set of diodes, then filtered by a capacitive inductive circuit

  citif In this case, the rectified voltage, present between terminals BE 1- 4 and BE 2-4, can have a nominal value of about 270 volts, but be subject to fluctuations

  between approximately 130 volts and 420 volts.

  The ETC-4 control stage here includes a modul-

  PWM-4 pulse width suitable for controlling the two field effect transistors TP-4 of the switching unit COM-4, mounted in half-bridge, via an isolation transformer TI -4 followed by two circuits

CFM-4 shaping machine.

  The TR-4 transformer has a plurality of windings

  secondary E Si-4 alternately wound over the whole length

  magnetic core NY-4 with a corresponding number

  of primary windings E Pij-4 connected in parallel to the uni-

  COM-4 controllable switching tee.

  Since the winding of this transformer has been carried out

  starting with a secondary winding and ending

  nant by a secondary winding, the number of primary windings is reduced by one unit compared to the number of secondary windings It would have been otherwise if we had started by winding a primary winding

  then a secondary winding and so on for termi-

ner by a primary winding.

  Subsequently, the index i + l will be replaced by the letter j

for simplification purposes.

  The ETS-4 output stage of this power supply then includes

  a plurality of downstream rectification cells C Ri-4 respec-

  tively connected to the plurality of secondary windings and all here consisting of a Graetz bridge These downstream rectification cells are also respectively followed by a plurality of downstream filter cells CF Ai-4 The downstream capacities C Ai-4 of these downstream filter cells are

  connected in series to each other to define a pre-

  first row which has a first downstream capacity

  mite CF Al-4 and a second downstream end capacity

CF An-4.

  A multiplicity of cells is also provided.

  auxiliary dressings CR Xi-4, all also made up

  here from a Graetz bridge respectively followed by a multi-

  plicity of auxiliary filter cells CFA Xi-4 The respective auxiliary capacities CA Xi-4 of these auxiliary filter cells are also connected in series

  to each other to define a second row poss-

  in a first CAX 1-4 end auxiliary capacity and a second CA Xm-4 auxiliary end capacity The first CAX 1-4 end auxiliary capacity is connected in series with the second downstream capacity

end C An-4.

  It should be noted here that the numbers N and m can be equal

or different.

  Two neighboring auxiliary rectifier cells CR Xi-4 and CR Xj-4 are connected in parallel by a capacitive link circuit C Lij-4 All these cells thus form a second row corresponding to said second row Then

  that it is essential that the first recovery cell

  auxiliary end CRX 1-4 is connected in parallel

  the, by means of a capacitive link circuit C Lnl-4, with the downstream rectification cell C Rn-4, it is also preferable that all the downstream rectification cells C Ri-4 are also connected to each other other

  by C Lij-4 capacitive link circuits to repair

  uniformly firing the charge of the different capacitors

link.

  Furthermore, as already mentioned above, it is particularly

  particularly advantageous that all the downstream inductors of the downstream filter cells, as well as all the auxiliary inductors of the auxiliary filter cells, are coupled together In this case, it is necessary that the two downstream inductors L Ali-4 and LA 2 d-4 two neighboring downstream filter cells connected to the common terminal

  of the two downstream capacities of these two neighboring cells CFA Xi-

  4 and CFA Xj-4, have opposite polarity It must be

  the same for the two auxiliary inductances of the two cells

  neighboring auxiliary filter cells connected to the common terminal of the two auxiliary capacitors of these two cells

  Practically all of these inductors are connected

  tees on the same magnetic core, starting for example by winding one on the other all inductors of the same polarity, for example the one shown in dashed lines

  in the figure, then all the polarity inductors oppo-

  sée (those shown in solid lines).

* The Applicant observed that it was preferable, in certain

  some applications, to have at the output of some of the downstream filter cells of the conventional voltage clipping circuits ECR 1-4 and EC Rn-4 which have been represented

  here very symbolically for the sake of simplification.

  The coupling of all the inductances of the wire cells-

  not only does it provide a parasitic

  te substantially equal to the parasitic capacity that would have an inductance taken in isolation, but also to have fewer clipping circuits than there are downstream filter cells In practice, the Applicant has observed that it was sufficient

  to have two clipping circuits at the outlet of the two

  downstream end filter lules.

  All downstream and auxiliary capacities deliver a substantially equal level of DC voltage across their terminals

  and thus contribute together to provide between the terminal of ex-

  end B Sl-4 of the first downstream capacity of end C Al-4

  and the second terminal B 53-4 of the second capacity

  CA Xm-4 end link an overall voltage which is the sum of all the elementary voltages supplied by these capacitors. The helix H of the TOP microwave tube is connected to this end terminal B 53-4 while the cathode K of the tube is connected to terminal B 51-4 Furthermore, the collector Co of the tube is connected to the common terminal B 52-4 of the second downstream end capacity C An-4 and of the first capacity

CAX 1-4 end auxiliary.

  This assembly is particularly well suited to a hyper tube

  frequency since the person skilled in the art knows that, in such a tube, the energy consumption is greater between

  the cathode and the collector only between the cathode and the propeller.

  Also, the supply thus described makes it possible to very quickly charge the downstream capacities of the downstream filtering cells,

  which allows the necessary power to be supplied very quickly

  between the collector and the cathode.

  Of course, the high voltage supplied to the output terminal B 51-4 of this power supply is subject to variations depending on the current draw of the tube Also, is it

  provided that the control stage includes control means

  REG-4 lation of the voltage delivered to the cathode K of the tube.

  These regulation means are suitable for reducing the high voltage supplied to the cathode to a lower value, for example by a divider bridge, then for comparing this reduced voltage to a reference value, the result of this comparison being supplied to the circuit to modulation of

  width PWM-4 which will modify the cyclical ratio accordingly

  only to restore the nominal output voltage.

  In addition, the use of a pulse width modulation circuit allowing regulation of the output voltage by modifying the duty cycle and not by modifying the switching frequency makes it possible in particular to maintain this latter synchronous frequency. -

  frequency of repetition of the radar associated with the TOP tube.

  The Applicant has thus produced a switching power supply of the direct conduction type capable of supplying between the terminals BSI-4 and B 53-4 a high voltage of the order of 400-0 volts by delivering to the terminals of each downstream and auxiliary capacity. a voltage of the order of 330 volts with a ratio N 2 of the number of turns of each secondary winding to each corresponding primary winding which is approximately equal to 4 The switching frequency is of the order of 500 kilohertz and the efficiency of such a

  diet has been estimated to be around 91%.

  The invention is not limited to the embodiment below.

  above described but embraces all variants contained therein

  naked in the context of the claims below.

Claims (11)

Claims.   1 Power supply device, comprising: two input terminals for a substantially direct voltage source, a transformer having a primary and a secondary, a control stage comprising a controllable switching unit capable of being connected sequentially, according to a predetermined control law, the primary at the two input terminals, an output stage comprising a downstream rectification cell connected to the secondary of the transformer, followed by a downstream filtering cell comprising an inductive circuit   downstream having a chosen inductive value as well as a capacity   downstream tee contributing to supply an output voltage, characterized in that the downstream inductive circuit comprises two downstream inductors (L Al-2, LA 2-2) having respective inductive values the sum of which is substantially equal to said chosen inductive value, and in that the two downstream inductors are respectively connected, in series with the downstream capacity (CA-2), on either side of this downstream capacity.   2 Device according to claim 1, characterized in that   that the inductive value of each downstream inductor is sensitive   roughly equal to half of said chosen inductive value sie.   3 Device according to one of the preceding claims,   characterized in that the two downstream inductors are connected   plied on the same magnetic core and are of opposite polarity sée.   4 Device according to one of the preceding claims,   characterized in that the transformer secondary comprises a secondary winding (ES-3), and in that the downstream rectification cell (CR-3) comprises four rectifiers mounted in Graetz bridge (Dl-3, D 4- 3) whose two input terminals are respectively connected to the two terminals of the secondary winding and whose two output terminals are respectively connected to   two terminals of the two downstream inductors (L Al-3, LA 2-3), oppo-   to those connected respectively to the terminals of the downstream capacity (CA-3).   Device according to one of the preceding claims,   characterized in that the output stage comprises at least   an auxiliary rectifying cell (CRX-3) functional-   similar to the downstream righting cell (CR-3),   followed by an auxiliary filter cell (CFAX-3) structured   turally analogous to said downstream filter cell (CFA-3),   and in that the auxiliary rectifier cell (CRX-3) is connected in parallel with the downstream rectifier cell (CR-3) via a capacitive link circuit (CL-3), while the capacitance auxiliary filter cell (CAX-3) is connected in series with the downstream capacity of the downstream filter cell (CA-3).   6 Device according to claim 5, characterized in that all the downstream and auxiliary inductors are coupled on the same magnetic core, the downstream inductor (L Al-3) of the downstream filter cell and the auxiliary inductor (LAX 2- 3) of the auxiliary filter cell, connected to the common terminal of the two downstream and auxiliary capacities   (CA-3, CAX-3) being of opposite polarity.   7 Device according to one of claims 5 and 6, charac-   terized in that the downstream and auxiliary rectification cells   each have a Graetz bridge, and in that the capacitive link circuit has two link capacitors (CL-3) respectively connected between the two homologous input terminals of the two Graetz bridges.   8 Device according to one of claims 5 to 7, character-   risé in that the transformer secondary comprises a plurality of secondary windings (E Si-4),   in that the output stage comprises a plurality of cells   the downstream rectification cells (C Ri-4) respectively followed by a plurality of downstream filtering cells (CF Ai-4), as well as a multiplicity of auxiliary rectification cells   (CR Xi-4) respectively followed by a multiplicity of cells   the auxiliary filtering (CFA Xi-4),   in that the downstream rectification cells are respective-   connected to the plurality of secondary windings,   the respective downstream capacities (C Ai-4) of the wire cells   downstream trage being connected in series with each other to define a first row having a first (C Al-4) and a second (C An- 4) downstream end capacities, in that the respective auxiliary capacities (CA Xi- 4)   auxiliary filter cells are connected in parallel   links to each other to define a second row having a first (CAX 1-4) and a second (CA Xm-4)   auxiliary end capacity, the first auxiliary capacity   end link being connected in series with the second downstream end capacity, and in that the auxiliary rectification cells are connected in parallel to each other by capacitive connection circuits (C Lij-4) thus forming a second line corresponding to said second row, the first auxiliary rectification cell (CRX 1-4) being connected in series, by means of a capacitive circuit of   link (C Lnl-4) with the downstream rectification cell (C Rn-   4) corresponding to the downstream filter cell (CF An-4)   having the second downstream end capacity (C An-4).   9 Device according to claim 8, characterized in that   that the downstream rectification cells are connected in parallel   links to each other by the capacitive link circuits to form a first line corresponding to said first row.   10 Device according to one of claims 8 and 9, charac-   terized in that all the downstream and auxiliary inductors are coupled together on the same magnetic core, the two downstream inductors of two neighboring downstream filter cells connected to the common terminal of the two capacitors   downstream of these two neighboring cells being of opposite polarity   sée, as well as the two auxiliary inductances of two neighboring auxiliary filter cells connected to the common terminal of the two auxiliary capacitors of these two neighboring cells.   11 Device according to one of claims 8 to 10, intended   born to feed a microwave tube comprising a propeller (H), a collector (CO) and a cathode (K), characterized   in that the cathode (K) is connected to the end terminal   tee (B Sl-4) of the first downstream end capacity (C Al-4), in that the collector is connected to the common terminal (B 52-4) of the second downstream end capacity (C An -4) and the first auxiliary end capacity (CAX 1-4), and in that the propeller is connected to the end terminal (B 53-4) of the second auxiliary end capacity (CA Xm-4).   12 Device according to one of the preceding claims,   characterized in that the control stage includes a pulse width modulation circuit (PWM-4).