EP3308455A1

EP3308455A1 - Dc-dc converter for controlling an aircraft fan inverter, and associated control method and fan

Info

Publication number: EP3308455A1
Application number: EP16731243.8A
Authority: EP
Inventors: Valéry CHAU; Philippe PRECIAT; Pascal Rollin; Sonia DHOKKAR
Original assignee: Safran Electrical and Power SAS
Current assignee: Safran Electrical and Power SAS
Priority date: 2015-06-11
Filing date: 2016-06-07
Publication date: 2018-04-18
Also published as: US10396650B2; FR3037453B1; WO2016198783A1; CN107852097A; FR3037453A1; US20180138800A1

Abstract

The invention concerns a DC-DC power converter, suitable for being powered by a primary voltage source and for powering an electronic control system of a three-phase inverter, said three-phase inverter being configured to control a fan of an aircraft ventilation system. The DC-DC converter is characterised in that it comprises a transformer (16), a primary circuit (12) comprising two loops forming a push-pull configuration, at least one secondary circuit (14) comprising a secondary winding (L_S), suitable for supplying, to the inverter, an output voltage equal to double the peak voltage at the terminals of the secondary winding (L_S), and, to a branch of the circuit suitable for supplying the inverter, an output voltage equal to the opposite of the peak voltage at the terminals of the secondary winding (L_S), and in that the controllable transistors (M1, M2) are suitable for each being switched to zero voltage.

Description

CONTINUOUS-CONTINUOUS CONVERTER FOR STEERING AN AIRCRAFT FAN INVERTER, CONTROL METHOD AND FAN THEREFOR

1. Technical field of the invention

The invention relates to the optimization of a structure of a DC-DC converter. In particular, the invention relates to a DC-DC converter for controlling a three-phase inverter, in particular a three-phase inverter driving a fan of a ventilation system of an aircraft.

2. Technological background

The ventilation systems for regulating the air circulation within an aircraft comprise at least one fan adapted to ensure air circulation in the aircraft, in particular in the cabin of the aircraft. Each fan is controlled by a three-phase inverter. The three-phase inverter comprises three supply arms, each of these arms comprising two isolated-gate bipolar transistors (IGBT for Insulated Gate Bipolar Transistor). The driving voltage requirements of the IGBT transistors are conventionally +15 V in positive bias voltage and -7.5 V in negative bias voltage. These voltages are provided by at least one DC-DC converter (DC-DC for Direct Current) and in general one IGBT transistor converter.

Nevertheless, new generations of fans have been developed, whose mass and volume have been significantly reduced. Thus, in order to benefit from these reductions in mass and volume, it is necessary to use suitable DC-DC converters. In particular, the DC-DC converters currently used have a large size and weight and a large number of components. Thus, they are no longer suitable for new generations of fans in which the space dedicated to the installation of the DC-DC converter is reduced. In addition, because of the reduction of this space, new thermal stresses appear, which current DC-DC converters are not suitable because their performance is too low and causes unacceptable thermal overheating in this reduced space. It is therefore necessary to propose a new type of DC-DC converter suitable for the new generations of aircraft ventilation system fans.

3. Objectives of the invention

The invention aims to overcome at least some of the disadvantages of known DC-DC converters.

In particular, the invention aims to provide, in at least one embodiment of the invention, a DC-DC converter comprising a reduced number of components.

The invention also aims to provide, in at least one embodiment of the invention, a DC-DC converter comprising few complex components.

The invention also aims to provide, in at least one embodiment of the invention, a DC-DC converter having a footprint and a reduced weight.

The invention also aims to provide, in at least one embodiment of the invention, a DC-DC converter having a high efficiency.

The invention also aims to provide, in at least one embodiment of the invention, a DC-DC converter whose heating is reduced. 4. Presentation of the invention

To do this, the invention relates to a DC-DC converter, adapted to be powered by a primary voltage source and to supply a control electronics of a three-phase inverter, said three-phase inverter being configured to drive a fan of a ventilation system of an aircraft, characterized in that it comprises:

a transformer, comprising two primary windings and at least one secondary winding,

a primary circuit, comprising a supply input adapted to be connected to a first terminal of the primary voltage source, said supply input being connected to two switching loops each comprising one of the primary windings of the transformer and a controllable transistor comprising a parasitic capacitance and thus forming a symmetrical arrangement,

at least one secondary circuit, comprising a secondary winding of the transformer, said secondary winding comprising two terminals connected on the one hand to a capacitive rectification bridge, adapted to supply the inverter control electronics with an equal positive output voltage at twice the peak voltage across the secondary winding, and secondly to a branch of the circuit adapted to supply the inverter control electronics with a negative output voltage equal to the opposite of the voltage peak at the terminals of the secondary winding,

and in that the controllable transistors are adapted to each be controlled by a driving signal between an on state and a off state, so that when a controllable transistor is in an on state, the other controllable transistor is in a state blocked and that when a controllable transistor is switched from the off state to the off state, the two controllable transistors are held in the off state for a dead time so as to perform a zero voltage switching.

In the remainder of the description, the control voltage of a transistor designates the voltage between the gate and the source for a field effect transistor, the output voltage at the terminals of a transistor indicates the voltage between the drain and the transistor. source for a field effect transistor and the current flowing through the transistor means the current between the drain and the source for a field effect transistor. The conducting state of the controllable transistors corresponds to a state in which a current flows through the transistor and the blocked state of the controllable transistors corresponds to a state in which the current flowing through the transistor is zero or negligible. The controllable transistors thus behave as controllable switches with parasitic capacitance in parallel, the on state corresponding to a closed switch and the off state corresponding to an open switch.

A DC-DC converter according to the invention thus makes it possible to control a control electronics of a three-phase inverter with a reduced number of components. In particular, the primary circuit comprises a symmetrical mounting (also called push-pull assembly) comprising only two transistors instead of four transistors in frequently used full-bridge structures. In addition, the structure of the secondary circuit of the DC-DC converter makes it possible to obtain two voltages at the output of the secondary circuit with a single secondary winding. Apart from the primary and secondary windings, the DC-DC converter does not include magnetic components, which generally have a large footprint. The DC-DC converter according to the invention therefore has a smaller footprint than current solutions.

The primary circuit comprises a symmetrical mounting controlled so as to perform a switching of the Zero Volt Switching transistors (or ZVS, for Zero Volt Switching in English). Thus, each controllable transistor is alternately in an on or off state, but when a controllable transistor goes from the on state to the off state, the other controllable transistor remains in the off state for a dead time, then passes in the passing state. This dead time is a time interval which makes it possible to minimize the switching losses due, in the prior art, to a voltage-current switching with non-zero values. The dead time during which the two transistors are blocked allows voltage-current switching to very low values, resulting in very low switching losses. Thus, the efficiency of the DC-DC converter is improved and heating is reduced.

Zero voltage switching is ensured during the dead time and by a particular combination of the primary windings and parasitic capacitances of the controllable transistors. A first controllable transistor is in the off state, the voltage at its terminals is at its maximum level and its parasitic capacitance is charged, a second controllable transistor is in the on state, the voltage at its terminals is at its minimum level and its parasitic capacitance is discharged. During the dead time, the two transistors are in the off state and the primary windings are no longer supplied with current by the primary voltage source. A magnetizing current of the transformer makes it possible to discharge the parasitic capacitance of the first controllable transistor and to charge the parasitic capacitance of the second controllable transistor. Once this charge and this discharge of the parasitic capacitances are completed, the switching can be done without loss: in fact, the transistor comprises a diode which is spontaneously initiated during the dead time. The primary windings and the controllable transistors are thus chosen so that their characteristics allow the switching to zero voltage. In particular, the parasitic capacitances of the transistors, the magnetizing current and the duration of the dead time are chosen so as to obtain zero voltage switching without addition of components.

The DC / DC converter according to the invention is therefore, in particular thanks to the combination of a push-pull arrangement, a capacitive rectification bridge and a zero voltage switching, perfectly adapted to the constraints of the new generations of Aircraft ventilation system fan, especially in terms of size, weight and thermal efficiency. In addition, its cost is reduced.

Advantageously and according to the invention, the three-phase inverter comprising a plurality of insulated gate bipolar transistor, the DC-DC electrical converter is characterized in that it comprises a plurality of secondary circuits each comprising a secondary winding of the transformer, each circuit secondary circuit being adapted to supply at least one insulated gate bipolar transistor of the control electronics of the three-phase inverter.

According to this aspect of the invention, the DC-DC converter supplies a plurality of insulated gate bipolar transistors of the three-phase inverter with a single primary power source. Each insulated gate bipolar transistor of the three-phase inverter requiring a secondary winding to obtain a positive and negative voltage, duplicate the number of secondary windings on the same transformer can drive a complete three-phase inverter, which allows a reduction of the size, weight and price of all DC-DC converters necessary for the control of a fan.

Advantageously and according to the invention, the controllable transistors are field effect transistors.

Preferably, the controllable transistors of the DC-DC converter are metal oxide-oxide field effect transistors (also called MOSFETs for Metal Oxide Semiconductor Field Effect Transistors). Other components may also be used, provided that they are supplemented by a free-wheeling diode.

The invention also relates to an aircraft system fan, characterized in that it is controlled by a three-phase inverter comprising a control electronics adapted to be powered by at least one DC-DC converter according to the invention.

Advantageously and according to this last aspect of the invention, the control electronics of the three-phase inverter comprises three supply arms, each arm being controlled by a DC-DC electrical converter according to the invention.

Advantageously and according to the invention, the control electronics of the three-phase inverter comprises three supply arms, and in that it comprises an electric converter according to the invention comprising six secondary circuits adapted to control the three arms of the three-phase inverter. food. The invention also relates to a control method of a DC-DC converter according to the invention, characterized in that it comprises controlling the two controllable transistors, said first controllable transistor and second controllable transistor, according to the following steps:

a first step of controlling the first transistor controllable in the on state and the second transistor controllable in the off state, a second transition step of the first transistor controllable in the off state and the maintenance of the second transistor controllable in the state blocked during the timeout,

a third step of controlling the second transistor controllable in the on state and the first transistor controllable in the off state, a fourth step of transition of the second transistor controllable in the off state and the maintenance of the first transistor controllable in the state blocked during the timeout.

The method according to the invention therefore allows control of the DC-DC converter comprising two transition stages in which the two transistors are in a locked state in order to allow a zero-switching of voltage.

The invention also relates to a DC-DC converter, a fan and a control method characterized in combination by all or some of the characteristics mentioned above or below.

5. List of figures

Other objects, features and advantages of the invention will become apparent on reading the following description given solely by way of non-limiting example and which refers to the appended figures in which:

FIG. 1 is a schematic view of a DC-DC electrical converter according to a first embodiment of the invention,

FIGS. 2a, 2b, 2c and 2d are diagrammatic views of a DC-DC converter according to the first embodiment of the invention during different stages of a method according to one embodiment of the invention,

FIG. 3 represents curves a, b, c respectively representing the control voltages of the controllable transistors, the voltages at the terminals of the controllable transistors and the intensities through the controllable transistors of a DC-DC converter according to the first embodiment of FIG. the invention,

FIG. 4 is a schematic view of a DC-DC converter according to a second embodiment of the invention,

Figure 5 is a schematic view of a supply chain comprising three DC-DC converters according to the second embodiment of the invention and a fan according to one embodiment of the invention.

6. Detailed description of an embodiment of the invention

The following achievements are examples. Although the description refers to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment, or that the features apply only to a single embodiment. Simple features of different embodiments can also be combined to provide other achievements. Figures, scales and proportions are not strictly adhered to for the purpose of illustration and clarity.

Figure 1 shows schematically a DC-DC converter 10 according to a first embodiment. The DC-DC converter comprises a primary circuit 12, a secondary circuit 14 and a transformer 16. The transformer 16 makes the connection between the primary circuit 12 and the secondary circuit 14. In particular, the transformer 16 comprises two perfectly coupled primary windings, a first primary winding L _P1 and a second primary winding L _P2 , and a secondary winding L _s . The primary windings L _P1 and L _P2 form part of the primary circuit 12 and the secondary winding L _s is part of the secondary circuit 14.

The primary circuit 12 is powered by a primary voltage source whose terminals are respectively connected to a supply input V, _N so as to supply the DC-DC converter. The supply input V, _N is connected to two parallel switching loops, a first loop and a second loop. The first loop comprises the first primary winding L _P1 and a first controllable transistor M ₁ , and the second loop comprises the second primary winding L _P2 and a second controllable transistor M ₂ . The two loops thus form a symmetrical assembly, also called push-pull assembly.

The energy delivered by the primary circuit 12 at the two primary windings is transmitted to the secondary circuit 14 via the transformer 16: the secondary winding L _s recovers a ratio of the primary voltage present at the two primary windings. In particular, the secondary winding L _s has a voltage V _SE c at its terminals. The terminals of the secondary winding L _s are connected on the one hand to a first branch comprising a capacitive rectification bridge, comprising two capacitors C _s and C _P and two diodes D _x and D ₃ forming a circuit called a Schenkel doubler and secondly to a second branch comprising a diode D ₂ and a capacitor C _N. Capacitor C _s acts as a capacitive doubler.

The first branch is adapted to provide a device, here represented by a resistor R _0U TI, a first output voltage V _0U TP equal to twice the peak voltage across the secondary winding L _s . Indeed, as visible on the 1, the voltage V _0U TP is equal to the sum of the voltage V _SEC , the voltage across the capacitor C _s and the voltage across the diode Gold, the voltage across the capacitor C _s is equal to sum of the voltage V _SEC and the voltage across the diode D ₃ . Neglecting the voltages of the diodes D ₁ and D ₃ is obtained V TP = _0U 2xV _SEC.

The second branch is adapted to provide a device, here represented by a resistor ₀ UT2, a second output voltage V ₀ UTN equal to the opposite of the peak voltage across the secondary winding L _s . Indeed, as shown in Figure 1, the output voltage V ₀ UTN is equal to the sum of the opposite of the voltage V _SE c and the voltage across the diode D ₂ . By neglecting the voltage of the diode D ₂ , we obtain V _0UT N = -V _SE c-

By dimensioning V _SE c peak = 7.5 V, we thus obtain V ₀ UTP = 15V and V ₀ UTN = -7.5 V, corresponding to the bias voltages generally required for transistors of the IGBT type used in three-phase inverters. For different voltage requirements, it is possible to obtain other values by dimensioning the number of turns of the secondary winding accordingly.

FIGS. 2a, 2b, 2c, 2d show a DC-DC electrical converter according to the first embodiment of the invention during different steps of a method according to one embodiment of the invention. These figures make it possible to see in more detail the operation of the DC / DC converter according to different stages related to the states of the two controllable transistors Mi, M ₂ . In these figures, the controllable transistors Mi, M ₂ are each represented, for simplification and for the sake of clarity, by a closed switch (representing a transistor controllable in the on state) or open (representing a controllable transistor in the state blocked), at the terminals of which is connected in parallel a parasitic capacitance of each controllable transistor, respectively a first parasitic capacitance C _DS1 of the first controllable transistor M ₁ and a second parasitic capacitance C _DS2 of the second controllable transistor M ₂ .

The method comprises the following steps:

a first step of controlling the first controllable transistor M ₁ in the on state and the second controllable transistor M ₂ in the state blocked,

a second transition step of the first controllable transistor M ₁ in the off state and the holding of the second controllable transistor M ₂ in the off state during a dead time,

a third step of controlling the second controllable transistor M ₂ in the on state and the first controllable transistor M ₁ in the off state,

a fourth transition step of the second controllable transistor M ₂ in the off state and the holding of the first controllable transistor Mi in the off state during a dead time.

FIGS. 2a and 2c show the DC-DC converter during the first and third stages respectively, in which a controllable transistor is in the on state and the other controllable transistor is in the off state.

The push-pull circuit of the primary circuit alternately feeds the first primary winding L _P1 or the second primary winding L _P2 . Thus, the current flowing in the secondary winding L _s changes direction according to the primary winding supplied. The first primary winding L _P1 is powered by the push-pull assembly when the first controllable transistor M ₁ is in the on state and the second controllable transistor M ₂ is in the off state, as shown with reference to FIG. 2a. The second primary winding L _P2 is energized when the first controllable transistor Mi is in the off state and the second controllable transistor M ₂ is in the on state, as shown with reference to FIG. 2c.

A first charging current passing through the resistor ₀ UTI and a second charging current passing through the resistor ₀ UT2 are provided differently depending on the direction of the current flowing through the secondary winding L _s . When the second primary winding L _P2 is energized, as shown with reference to FIG. 2c, the capacitor C _s charges up to V _{SEC C} , the capacitor C _P supplies the first charging current, the capacitor C _N is charged up to V _SEC crest and the secondary winding L _s provides the second charging current. When the first primary winding L _P1 is energized, as shown with reference to FIG. 2a, the capacitor C _s discharges into the capacitor C _P and supplies the first current of load, the capacitor C _N provides the second charging current.

FIGS. 2b and 2d show the DC / DC converter during the second and fourth stages respectively, in which the two controllable transistors are in the off state.

These steps are transition steps, making it possible to obtain a zero-voltage switching by keeping the two controllable transistors in the off state during a dead time.

The second step follows the first step in which the first controllable transistor Mi was conducting. Thus, at the beginning of the second step, the first parasitic capacitance C _DS i of the first controllable transistor Mi is discharged and the output voltage across the first controllable transistor Mi is at its minimum level, that is to say close to zero. The second controllable transistor M ₂ being blocked in the first and the second step, the second parasitic capacitance C of the second controllable transistor M ₂ is charged and the output voltage across the second controllable transistor M ₂ is at its maximum level. The two primary windings are no longer powered by the primary voltage source and a magnetizing current propagates in the direction indicated by the arrows on the two loops in Figure 2b. This magnetising current causes the charge of the first parasitic capacitance C _DS1 and the discharge of the second parasitic capacitance C _DS2 . Thus, the output voltage across the first controllable transistor M ₁ increases gradually and the output voltage across the second controllable transistor M ₂ decreases gradually. To adjust the rate of growth or decrease of voltages, the parasitic capacitance consists only of that of the controllable transistor.

In a symmetrical manner, in the fourth step shown with reference to FIG. 2d, the first parasitic capacitance C _DS i discharges, the output voltage at the terminals of the first controllable transistor Mi gradually decreases, the second parasitic capacitance C _DS2 is charged and the output voltage across the second controllable transistor M ₂ increases gradually.

The second step and the fourth step last during a predefined dead time depending on the characteristics of the primary windings and parasitic capacitors, so that the end of the dead time, the voltages across the transistors can reach the maximum value if the voltage increases during the step, or the minimum value if the voltage decreases during the step.

In practice, the dead time T _M optimal for an optimal voltage zero switching of a controllable transistor is expressed by the formula:

With TON the control time in the on state of the controllable transistor, C _DS the parasitic capacitance of the controllable transistor and L _P the inductance of the primary winding located in the same loop as the controllable transistor considered.

FIG. 3 represents three curves a, b and c respectively representing, as a function of time, the control voltages V _gs _ _M1 and V _gs _ _M2 respectively of the first controllable transistor M ₁ and the second controllable transistor M ₂ (curves 30 and 32 ), the output voltages V _ds _ _M1 and V _ds _ _M2 across respectively the first controllable transistor M ₁ and the second controllable transistor M ₂ (curves 34 and 36), and the intensities l _d _ _M1 and l _d _M2 respectively passing through the first controllable transistor M ₁ and the second controllable transistor M ₂ (curves 38 and 40) of a DC-DC converter according to the first embodiment of the invention.

The curves 30, 34, 38 in solid lines are associated with the first controllable transistor Mi, and the curves 32, 36, 40 in dashed lines are associated with the second controllable transistor M ₂ .

The time zones numbered 1, 2, 3 and 4 correspond respectively to the first, second, third and fourth stages of the control method according to the invention. Curve a thus represents the commands sent to the controllable transistors, the high level representing a control of the transistor that can be controlled in the on state and the low level representing a control of the controllable transistor in the off state. The commands are transmitted for example by a dedicated circuit (not shown), or by an already existing control card, for example an FPGA.

During the first step, in the time zone 1, the first controllable transistor M ₁ is controlled in the on state: the output voltage V _ds _ _M1 at its terminals is therefore zero, and the intensity l _d _ _M1 of current passing through it non-zero. The second controllable transistor M ₂ is controlled in the off state: the output voltage V _ds _ _M2 to its terminals is therefore non-zero and the intensity l _d _ _M2 of the current passing through it is zero (or negligible).

During the second step, in the time zone 2 of a duration equal to the dead time described above, the two controllable transistors are controlled in the off state: the output voltage V _ds _ _M1 across the first controllable transistor M ₁ progressively increases because of the charge of the first parasitic capacitance C _DS1 , and the output voltage across the second controllable transistor M ₂ decreases due to the discharge of the second parasitic capacitance C _DS 2. The intensities of the currents flowing through the transistors controllables are close to zero, corresponding to the magnetizing currents crossing parasitic capacitances. At the beginning of the dead time, the intensity l _d MI of the current flowing through the first controllable transistor Mi is brought to a zero or negligible value before the progressive increase of the output voltage V _ds _ _M1 across the first controllable transistor Mi. There are therefore no losses due to the switching of the first controllable transistor M ₁ from the off state to the off state of the first step. At the end of the dead time, the intensity l _d _ _M2 of the current flowing through the second controllable transistor M ₂ is zero or negligible and the output voltage V _ds _ _M2 across the second controllable transistor M ₂ has progressively reached a zero value. or negligible. There are therefore no losses due to the switching of the second controllable transistor M ₂ from the off state to the on state at the beginning of the third step. The commutations of the two controllable transistors are therefore ZVS (Zero Voltage Switching) Zero Voltage Switching.

The third and fourth steps are similar to the first and second steps, the role of the two controllable transistors being reversed.

By virtue of this zero-voltage switching, the efficiency of the DC-DC converter according to the invention is greater than 85% when the DC-DC converter is subjected to a temperature of between -50 ° C. and 115 ° C., which is superior to the converters of the prior art.

FIG. 4 diagrammatically represents a DC / DC converter 10 'according to a second embodiment. The DC-DC converter comprises, identically to the first embodiment described previously, a primary circuit and a first secondary circuit 42 comprising a first secondary winding, providing voltages V _0U TP_HS and V _0U T _N _HS-

In this embodiment, the DC-DC converter further comprises a second secondary circuit 44, identical to the first secondary circuit 42, comprising a second secondary winding. The transformer 16 'thus comprises the two primary windings described above, as well as the first secondary winding L _S i and the second secondary winding L _S 2- The second secondary circuit 44 makes it possible to obtain new output voltages, a voltage VO _U TP_LS and a voltage V _0U T _N _LS, with a single primary circuit and a single primary power source. A possible use of these new output voltages is described below with reference to FIG.

FIG. 5 shows a supply chain comprising three DC-DC converters 10a, 10b, 10c according to the second embodiment of the invention and a fan 50 according to one embodiment of the invention. The fan 50 is powered by a three-phase inverter 52 comprising three supply arms 54a, 54b, 54c, the supply arms 54a, 54b, 54c forming a control electronics. Each power supply arm 54a, 54b, 54c comprises two IGBT transistors (not shown), a high-level IGBT transistor (HS) and a low-floor (LS) transistor. . In the prior art, each IGBT transistor of each branch had to be fed by a DC-DC converter, the three-phase inverter being fed by six DC-DC converters. In some solutions of the prior art, the three low-floor IGBT transistors are powered by a single power supply, the three-phase inverter being fed by four DC-DC converters. The 10 'DC-DC converter according to the second embodiment previously described with reference to FIG. 4 makes it possible to simultaneously power a high-stage IGBT transistor, by virtue of the output voltages V _0U TP_HS and V _0U T _N _HS, and a low stage IGBT transistor a feed arm, through the output voltages V and V _0U _0U TP_LS T _N _LS- The three-phase inverter therefore requires only three converters 10a, 10b, 10c DC-DC.

Thus, each supply arm 54a, 54b, 54c is powered by a converter 10a, 10b, 10c continuous, each converter 10a, 10b, 10c DC-DC being supplied by a source 56a, 56b, 56c primary power supply.

According to an alternative embodiment not shown, the DC-DC converter comprises six secondary circuits, thus making it possible to supply all of the power supply arms of the control electronics of a three-phase inverter.

Claims

A DC-DC power converter adapted to be powered by a primary voltage source (56a, 56b, 56c) and to power a control electronics of a three-phase inverter (52), said three-phase inverter (52) being configured to driving a fan (50) of a ventilation system of an aircraft, characterized in that it comprises:

a transformer (16, 16 '), comprising two primary windings (L _P1 , L _P2 ) and at least one secondary winding (L _s , L _S1 , L _S2 ),

a primary circuit (12) comprising a supply input (V, _N ) adapted to be connected to a first terminal of the primary voltage source, said supply input (V, _N ) being connected to two loops of switching each comprising one of the primary windings of the transformer (16, 16 ') and a controllable transistor (Mi, M ₂ ) comprising a parasitic capacitance (C _DS i, C and thus forming a symmetrical arrangement,

at least one secondary circuit (14, 42, 44), comprising a secondary winding (L _s , L _S i, L of the transformer, said secondary winding (L _s , L _S1 , L _S2 ) comprising two terminals connected on the one hand to a capacitive rectifying bridge, adapted to supply the inverter control electronics (52) with a positive output voltage equal to twice the peak voltage across the secondary winding (Lj, Lsi, and d on the other hand to a branch of the circuit adapted to supply the inverter control electronics (52) with a negative output voltage equal to the opposite of the peak voltage across the secondary winding (L _s , L _S i, L

and in that the controllable transistors (Mi, M ₂ ) are adapted to each be controlled by a driving signal between an on state and a off state, so that when a controllable transistor is in an on state, the other transistor is in a locked state and that when a controllable transistor is controlled from the on state to the off state, the two controllable transistors (Mi, M ₂ ) are maintained in the locked state during a dead time so as to perform a zero voltage switching.

2. DC-DC power converter according to claim 1, the three-phase inverter (52) comprising a plurality of insulated gate bipolar transistor, the DC-DC converter being characterized in that it comprises a plurality of secondary circuit (42). , 44) each comprising a secondary winding (Lsi, 2) of the transformer (16, 16 '), each secondary circuit being adapted to supply at least one insulated gate bipolar transistor of the control electronics of the three-phase inverter.

3. DC-DC power converter according to one of claims 1 or 2, characterized in that the controllable transistors (Mi, M ₂ ) are field effect transistors.

4. Aircraft system ventilator, characterized in that it is controlled by a three-phase inverter (52) comprising a control electronics adapted to be powered via at least one electric converter (10, 10 ', 10a, 10b, 10c ) continuously-continuous according to one of claims 1 to 3.

Aircraft system ventilator according to Claim 4, characterized in that the control electronics of the three-phase inverter (52) comprise three supply arms (54a, 54b, 54c), each arm being controlled by a DC-DC converter (10 ', 10a, 10b, 10c) according to one of Claims 1 to 3.

Aircraft system ventilator according to Claim 4, characterized in that the control electronics of the three-phase inverter (52) comprise three supply arms (54a, 54b, 54c), and in that comprises an electric converter (10 ', 10a, 10b, 10c) according to one of claims 1 to 3 comprising six secondary circuits (14, 42, 44) adapted to drive the three supply arms (54a, 54b, 54c) .

7. A method of controlling a DC-DC converter (10, 10 ', 10a, 10b, 10c) according to one of claims 1 to 3, characterized in that it comprises the control of the two controllable transistors, so-called first controllable transistor (Μχ) and second controllable transistor (M ₂ ), according to the following steps:

a first step of controlling the first controllable transistor (Μχ) in the on state and the second controllable transistor (M ₂ ) in the off state,

a second transition step of the first controllable transistor (Mi) in the off state and the holding of the second controllable transistor (M ₂ ) in the off state during the dead time,

a third step of controlling the second controllable transistor (M ₂ ) in the on state and the first controllable transistor (Μχ) in the off state,

a fourth transition step of the second controllable transistor (M ₂ ) in the off state and the holding of the first controllable transistor (Μχ) in the off state during the idle time.