DC-DC CONVERSION DEVICE, ELECTRICAL SYSTEM WITH SUCH A DC-DC CONVERSION DEVICE AND MOBILITY VEHICLE

Abstract

This device (800) comprises: - first and second DC-DC converters (112a, 112b) each comprising: a transformer (Ta, Tb), a primary circuit (CPa, CPb) designed to operate at high voltage, a secondary circuit (CSa, CSb) designed to operate at low voltage, the secondary circuit (CSa, CSb) comprising at least one switching element and a control circuit (CCa, CCb) designed to control the switching element; and - a low voltage circuit (CBT) carried by the electronic board (1102) and including at least the secondary circuits (CSa, CSb).There is a quadrilateral (Q) with four vertices located respectively on the two transformer pins, the high-voltage primary circuits and the transformer primary windings extending out of the quadrilateral (Q); at least one control circuit (CCa, CCb) extends from one side of the quadrilateral (Q); and the device (800) includes a component located on the other side of the quadrilateral (Q), as well as a connection (1202a, 1202b) between the control circuit and the component, this connection (1202a, 1202b) passing through the quadrilateral (Q) via the two lines (L1, L2). Figure for the abstract: Fig. 12.

Description

Title of the invention: DC-DC CONVERSION DEVICE, ELECTRICAL SYSTEM WITH SUCH A DC-DC CONVERSION DEVICE AND MOBILITY DEVICE Technical field of the invention

[0001] The present invention relates to a DC-DC conversion device, an electrical system with such a DC-DC conversion device and a mobility device.

[0002] A mobility device is, for example, a motorized land vehicle, a train, an aircraft, or a drone. A motorized land vehicle is, for example, a car, a motorcycle, a motorized bicycle, or a motorized wheelchair. Technological background

[0003] A DC-DC conversion device is known from the prior art, comprising: - an electronic card; - the first and second DC-DC converters, each comprising: • a transformer carried by the electronic board, with: - a primary coil, - a secondary coil, - at least one pin of a terminal at the first end of the secondary coil, and - at least one pin of a terminal at the second end of the secondary coil; • a primary circuit carried by the electronic board and connected to the primary coil of the transformer and designed to operate at high voltage; • a secondary circuit carried by the electronic board and connected to the secondary coil of the transformer and designed to operate at low voltage, the secondary circuit comprising at least one switching element; • a control circuit carried by the electronic board and designed to control the switching element; - a low voltage circuit carried by the electronic board and including at least the secondary circuits.

[0004] The control circuit generally needs to be connected to other components, for example to the switching element or to a driver thereof, or to sensors. These components are sometimes located away from the control circuit. on the circuit board. The presence of primary circuits operating at high voltage makes routing between the control circuit and these components difficult. Indeed, traversing a high-voltage circuit requires maintaining significant isolation distances, which conflicts with the desired compactness of a circuit board.

[0005] It may therefore be desirable to provide a DC-DC conversion device that makes it possible to overcome at least some of the aforementioned problems and constraints. Summary of the invention

[0006] A DC-DC conversion device is therefore proposed, comprising: - an electronic card; - the first and second DC-DC converters, each comprising: • a transformer carried by the electronic board, with: - a primary coil, - a secondary coil, - at least one pin of a terminal at the first end of the secondary coil, and - at least one pin of a terminal at the second end of the secondary coil; • a primary circuit carried by the electronic board and connected to the primary coil of the transformer and designed to operate at high voltage; • a secondary circuit carried by the electronic board and connected to the secondary coil of the transformer and designed to operate at low voltage, the secondary circuit comprising at least one switching element; • a control circuit carried by the electronic board and designed to control the switching element; - a low voltage circuit carried by the electronic board and including at least the secondary circuits; characterized in that: - there exists a quadrilateral with four vertices located respectively on the pin of the first end terminal of the secondary coil of the first transformer, the pin of the second end terminal of the secondary coil of the first transformer, the pin of the first end terminal of the secondary coil of the second transformer and the pin of the second end terminal of the secondary coil of the second transformer, the high voltage primary circuits and the primary coils of the transformers extending out of the quadrilateral; - at least one control circuit extending on one side outside the first and second lines forming sides of the quadrilateral (Q) extending from one transformer to the other; and - the DC-DC conversion device includes a component located outside the quadrilateral on a different side of the lines than the control circuit, and a connection between the control circuit and the component, this connection passing through the quadrilateral through the two lines.

[0007] Thus, thanks to the invention, it is possible to connect the control circuit by passing between the transformers and thus avoiding the primary circuits connected to the primary coils of these transformers.

[0008] The invention may further include one or more of the following optional features, according to any technically possible combination.

[0009] Optionally, the first DC-DC converter is designed to convert a first input voltage into an output voltage.

[0010] Optionally, the second DC-DC converter is designed to convert a second input voltage into the same output voltage as the first DC-DC voltage converter.

[0011] Optionally, the component is either the switching element or a driver of that switching element.

[0012] Optionally, the component is a current or temperature or voltage sensor and the connection is designed to provide the sensor measurements to the control circuit.

[0013] Optionally also, the DC-DC conversion device further includes an output capacitance having at least one capacitive element and designed to present between two terminals an output voltage of the first and second DC-DC converter and in which the low voltage circuit includes in the quadrilateral said capacitive element.

[0014] Optionally also, the connection is formed at least in part by an internal layer of the electronic board.

[0015] Optionally, the quadrilateral is also a rectangle.

[0016] Optionally, the control circuits are also located on the same side of the quadrilateral.

[0017] An electrical system comprising: is also proposed - a first and a second source of direct current voltage; and - a DC-DC conversion device according to the invention in which the first DC-DC converter is connected to the first DC voltage source to receive its input voltage and in which the second DC-DC converter is connected to the second DC voltage source to receive its input voltage.

[0018] A mobility device comprising a conversion device is also proposed continuous-continuous according to the invention or an electrical system according to the invention. Brief description of the figures

[0019] The invention will be better understood with the aid of the following description, given solely by way of example and made with reference to the accompanying drawings in which: - [Fig. 1] is a very simplified view of a mobility device in which the invention can be implemented, - [Fig.2] is an electrical circuit of a DC-DC converter according to a first embodiment with an inverter, a resonant circuit and a rectifier, - [Fig.3] shows an example of a switching circuit and rectifier of a DC-DC converter from [Fig.2], - Figure 4 groups together timing diagrams of electrical quantities of the DC-DC converter from Figures 2 and 3 when the control variable is a phase shift, - Figure 5 groups together timing diagrams of electrical quantities of the DC-DC converter of Figures 2 and 3 when the control variable is a phase shift in the absence of switching to the second mode according to the invention, - [Fig. 6] is a circuit of another example of a rectifier for the DC-DC converter in Figures 2 and 3, - Figure 7 is a functional view of a computer system that can be used in the DC-DC converter. - [Fig.8] is an electrical circuit of a DC-DC conversion device according to a second embodiment, - [Fig.9] is an electrical circuit of a transformer and a rectifier of the DC-DC conversion device of the second embodiment, - [Fig. 10] is a top view of the DC-DC converter device of [Fig. 9] when mounted on an electronic board, - [Fig. 11] is an enlargement of the view in [Fig. 10], illustrating in particular an arrangement of two transformers in the DC-DC conversion device, - Figure 12 is a simplified view of another example of transformer arrangement, and - [Fig. 13] is a simplified view of yet another example of transformer arrangement. Detailed description of the invention

[0020] With reference to [Fig. 1], a mobility device 100 in which the invention can be used, will now be described.

[0021] The mobility device 100 includes a propulsion system 102, for example, drive wheels 104 and an electric motor 106 designed to drive the drive wheels 104. The mobility device 100 further includes a battery 108 designed, for example, to electrically power the electric motor 106. The battery 108 is designed to provide a direct current voltage, called the battery voltage VBAT. This is a high voltage, i.e., greater than 100 V, preferably greater than 150 V. Thus, conversely, a low voltage is a voltage less than 100 V.

[0022] The mobility device 100 further comprises a low-voltage network 110 designed to be supplied by a direct current voltage, referred to as the network voltage LV. A low voltage is a voltage less than or equal to 100 V, preferably less than or equal to 60 V.

[0023] To obtain the mains voltage VBT from the battery voltage VBAt, the mobility device includes a DC-DC converter 112 designed to convert the battery voltage VBAt into the mains voltage VBT. The battery voltage VBAT and the mains voltage VBT thus form, respectively, an input voltage and an output voltage of the DC-DC converter 112.

[0024] With reference to [Fig.2], an example of a DC-DC converter 112 will now be described.

[0025] The DC-DC converter 112 is an LLC converter and thus comprises first of all an inverter 202, a resonant circuit 204 and a rectifier 206.

[0026] The inverter 202 is designed to convert an input voltage (the battery voltage VBAT when used in the context of [Fig.1]) into a first intermediate voltage Vl~ alternating current.

[0027] More specifically, the inverter 202 includes a switching circuit 208 and a control device 210 designed to control the switching circuit 208 in order to maintain an output voltage VOut (the voltage VBT when used in the context of [Fig.1]) at a desired setpoint VOut*, received by the control device 210.

[0028] The resonant circuit 204 comprises a transformer T, as well as a capacitor C and an inductor L in series with a primary coil P of the transformer T and the first intermediate voltage Vl~. The transformer T has a magnetizing inductance Lm. Thus, the capacitor C and the inductances L, Lm define a resonant frequency FR of the resonant circuit 204, for example between 80 and 120 kHz, for example 100 kHz.

[0029] The rectifier 206 is connected to a secondary coil S of the transformer T, designed to present a second intermediate voltage V2~ alternating current. The rectifier 206 is thus designed to convert this second intermediate voltage V2~ present at the secondary coil S of the transformer T into the output voltage VOut-. In some embodiments, the rectifier 206 may include one or more switches. controllable (e.g. transistor-controlled), e.g. controlled by control circuit 210.

[0030] The DC-DC converter 112 further includes, for example, a voltage sensor 212 designed to measure the output voltage VOut and provide this measurement to the control device 210, so that the latter regulates the output voltage VOut to the setpoint V0UT*.

[0031] With reference to [Fig.3], an example of a switching circuit 208 and rectifier 206 will now be described.

[0032] In this example, the switching circuit 208 comprises a complete bridge of controllable switches G1A, G1B, G2A, G2B, for example, controllable transistors. Thus, the switching circuit 208 has two switching arms. Each switching arm has two switches G1A, G1B and G2A, G2B connected to each other at a midpoint and together presenting the input voltage ViN. The first intermediate voltage Vi is thus present between the two midpoints of the two switching arms.

[0033] In this example, the rectifier 206 includes a capacitor Co, one terminal of which is connected to a middle terminal M of the secondary coil S of the transformer T. The rectifier 206 also includes two switches Q1, Q2, such as controllable transistors or diodes, connected respectively between one of the two end terminals S1, S2 of the secondary coil S of the transformer T, and a second terminal of the capacitor Cout connected to ground. Furthermore, each of the two switches Q1 and Q2 is connected to a different end terminal S1, S2.

[0034] The control device 210 is designed to control the switching circuit 208 selectively according to first and second modes.

[0035] In the first mode, the switching circuit 208 is controlled at a fixed switching frequency FD and substantially equal to the resonance frequency FR, for example equal to the resonance frequency FR to within 5%, preferably to within 1%, preferably below the resonance frequency FR.

[0036] For example, the switching circuit 208 is controlled by modifying a control variable. For example, in the case where the inverter 202 has two switching arms as illustrated in [Fig. 3], the first mode is a phase-shift modulation mode where the control variable can be a phase shift PHI between the two switching arms, the duty cycle for each of the switching arms being, for example, fixed at 50%.

[0037] By using the switching frequency FD close to the resonant frequency FR, very high efficiency can be achieved. For example, a power efficiency greater than 90% can be obtained. However, this method is not possible in below a certain input voltage level V^.

[0038] For example, when using the phase shift PHI, the lower the input voltage V1N, the more the phase shift PHI needs to be increased. However, the phase shift PHI can only be increased up to 180°.

[0039] In the second mode, the switching circuit 208 is controlled by changing the switching frequency FD below the resonant frequency FR. Using a switching frequency FD lower than the resonant frequency FR increases the gain between the input voltage V1N and the output voltage VOut, thus enabling the desired setpoint VOut* to be reached, even at input voltage levels V1N that are too low to continue operating at the resonant frequency FR.

[0040] For example, in this second mode, the control variable, for example the phase shift PHI, is kept fixed.

[0041] To switch from the first mode to the second mode, the control device 210 is, for example, designed to detect when the control variable reaches a threshold, for example, to detect when the phase shift PHI, when used, reaches 180°. To switch from the second mode to the first mode, the control device 210 is, for example, designed to detect when the switching frequency FD reaches approximately the resonance frequency FR, for example, to within 5%, preferably to within 1%.

[0042] Alternatively, the control device 210 could be designed to switch from one mode to another by comparing the input voltage V1N to a threshold: the control device 210 would be in the first mode when the input voltage was above this threshold, and in the second mode when the input voltage was below this threshold.

[0043] Thus, with reference to [Fig.4], an example of the operation of the control device 210 will now be described, more particularly in the case where the control variable is the phase shift PHI.

[0044] Initially, in a phase 402, the control device 210 controls the switching circuit 208 according to the first mode, i.e., with the switching frequency FD substantially equal to the resonant frequency FR. The regulation of the output voltage VOut is achieved by modifying the phase shift PHI. In particular, when the input voltage decreases, the phase shift PHI is increased.

[0045] At time 404, the phase shift reaches a predefined threshold S, for example 180°.

[0046] The control device 210 detects that this threshold S is reached by the shift of phase PHI and then, in phase 406, controls the switching circuit 208 according to the second mode, that is, by modifying the switching frequency FD below the resonant frequency FR. In particular, the lower the input voltage Vin, the more the The switching frequency FD is decreased. Conversely, when the input voltage V1N increases, the switching frequency FD is increased.

[0047] At time 408, the switching frequency FD reaches substantially the resonance frequency FR.

[0048] The control device 210 detects that the resonance frequency FR is reached and then controls again, in a phase 410, the switching circuit 208 according to the first mode.

[0049] In the example of [Fig.4], the switch from one mode to the other takes place around 210 V. Thus, alternatively, the control device 210 could switch from one mode to the other depending on whether the input voltage V1N is above or below this threshold of 210 V, as explained previously.

[0050] With reference to [Fig.5], in the absence of the switch to the second mode, when the input voltage V1N becomes too low (below approximately 210 V in the illustrated example) and it is no longer possible to play with the phase shift PHI because it is at its maximum of 180°, the output voltage VOut can no longer follow the setpoint VOut * and therefore falls at the same time as the input voltage Vin, until reaching, in the illustrated example, an asymptote when the input voltage VIN stabilizes.

[0051] With reference to [Fig.6], another example of rectifier 206 will now be described.

[0052] In this example, the rectifier 206 comprises a complete bridge of switching elements, for example controllable transistors. Alternatively, the switching elements could be diodes.

[0053] The rectifier 206 of [Fig.6] operates in the manner previously described for the rectifier 206 of [Fig.3].

[0054] With reference to [Fig.7], the control device 210 can be a computer system comprising a data processing unit 702 (such as a microprocessor) and a main memory 704 (such as RAM, from the English "Random Access Memory") accessible by the processing unit 702. The computer system further comprises, for example, a network interface and / or a computer-readable medium, such as, for example, a local medium (such as a local hard disk 706) or a remote medium (such as a remote hard disk accessible via the network interface through a communication network) or a removable medium (such as a USB flash drive, from the English "Universal Serial Bus", or a CD, from the English "Compact Disc" or a DVD, from the English "Digital Versatile Disc") readable by means of an appropriate reader of the computer system (such as a USB port or a CD and / or DVD disc drive).A computer program 708 containing instructions for the processing unit 702 is stored on the medium 706 and / or downloadable via the network interface. This computer program 708 is, for example, intended to be loaded into the main memory 704, so that the processing unit 702... executes its instructions.

[0055] Alternatively, all or part of the computer program 708 could be implemented in the form of hardware modules, i.e. in the form of an electronic circuit, for example micro-wired, not involving a computer program.

[0056] With reference to [Fig.8], a DC-DC converter device 800 will now be described. The device 800 can, for example, replace the converter 112 in the mobility device 100 of [Fig.1].

[0057] Device 800 incorporates voltage converter 112, duplicating it to achieve redundancy. Device 800 therefore comprises two voltage converters, 112a and 112b. Thus, the reference numerals used in the preceding figures will be retained, with the addition of the letter "a" for the elements of voltage converter 112a and the letter "b" for the elements of voltage converter 112b.

[0058] Only the output capacity Cour is not duplicated, but common to both converters 112a, 112b.

[0059] The device 800 is thus designed to receive two input voltages ViNa, ViNb to provide an output voltage VOut- When used in the context of [Fig. 1], the input voltages V^a, V^b are, for example, each equal to half the battery voltage VBat- Alternatively, the input voltages could both be equal to the battery voltage VBAt-

[0060] With reference to [Fig.9], the device 800 includes at least one loop B passing through the output capacitor COut and extending from one terminal to another of the secondary coil Sa of the transformer Ta.

[0061] In [Fig.9], the loop B extends from the second end terminal S2b to the terminal median Mb and also passes through switch Q2a.

[0062] More specifically, each terminal S1a, S2a, Ma has at least one pin, four in the illustrated example, shown in dashed lines. Furthermore, the output capacitor C1 has one or more capacitive elements, and each switch Q2a, Q2b has one or more switching elements. The capacitive elements are, for example, in parallel with each other. In addition, the capacitive elements can be arranged in at least two alignments, as in the illustrated example where they are arranged in two, for example, parallel, alignments. Preferably, each alignment has at least three capacitive elements. Even more preferably, all alignments have the same number of capacitive elements.

[0063] Thus, the loop B extends from one of the pins of the middle terminal Ma to one of the pins of the second end terminal S2a, passing through one of the switching elements of the switch Q2a and through at least one of the capacitive elements.

[0064] It is also possible to define other loops such as loop B, depending on the connected pins, the switch Q2a or Q2b through which the loop passes, the switching element of this switch Q2a or Q2b through which the loop passes, and the capacitive element of the output capacitor COut through which the loop passes. For example, it is possible to define another loop extending from the mid terminal Ma to the first end terminal Sla and passing through the switching element Qla and one of the capacitive elements of the output capacitor COut-

[0065] Loops can be defined in a similar way for the transformer Tb.

[0066] To minimize the parasitic output inductance, the output capacitance COut is placed sufficiently close to the secondary coils Sa, Sb of the two transformers Ta, Tb, so that, for each transformer Ta, Tb, at least one possible loop, preferably each of the possible loops, has an inductance of at most 20 nanohenry (nH).

[0067] With reference to [Fig. 10], the device 800 comprises an electronic board 1102 on one side of which the transformers Ta, Tb, the capacitive elements of the output capacitor Cour and the switching elements of the switches Qla, Q2a, Qlb, Q2b are mounted.

[0068] The electronic board 1102 includes a high-voltage input 1104 designed to receive the battery voltage VBat and divide it into the input voltages ViNa ViNb, and a low-voltage output 1106 designed to provide the output voltage VOut-

[0069] For each converter 112a, 112b, the electronic board 1102 carries a primary circuit CPa, CPb, a secondary circuit Csa, CSb and a control circuit CCA, CCb.

[0070] The primary circuit CPa, CPb is connected between the high voltage input 1104 and the primary coil Pa, Pb of the transformer Ta, Tb. This primary circuit CPa, CPb includes in particular the switching circuit 202a, 202b and the resonant circuit 204a, 204b and is designed to operate at high voltage.

[0071] The secondary circuit CSa, CSb is connected between the secondary winding Sa, Sb of the transformer Ta, Tb and the low-voltage output 1106. This secondary circuit CSa, CSb includes, in particular, the rectifier 206a, 206b and is designed to operate at low voltage. The secondary circuit CSa, CSb thus includes at least one switching element, namely one or more switches Qla, Q2a, Qlb, Q2b.

[0072] The CCa control circuit is designed to control the switching elements of switches Q1a, Q2a. It includes, for example, a microcontroller uCa. Similarly, the CCb control circuit is designed to control the switching elements of switches Qlb, Q2b. It includes, for example, a microcontroller uCb.

[0073] The secondary circuits CSa, CSb are thus part of a low voltage circuit CBT carried by the electronic board 1102.

[0074] With reference to [Fig. 11], the secondary coils Sa, Sb of the transformers Ta, Tb are placed opposite each other, so that only the low voltage circuit CBT extends into the area of ​​the electronic board 1102 separating the secondary coils Sa, Sb. To define this area more precisely, it is approximated as a quadrilateral Q, extending in particular in the plane of the electronic board 1102, with four vertices located respectively on a pin of the first end terminal Sla, a pin of the second end terminal S2a, a pin of the first end terminal Slb, and a pin of the second end terminal S2b. Thus, only the low-voltage circuit CBT extends within quadrilateral Q. In particular, the primary circuits CPa, CPb and the primary windings Pa, Pb of the transformers Ta, Tb extend outside quadrilateral Q. For example, as in the illustrated example, this quadrilateral Q is a rectangle."Extending within the quadrilateral" means that the orthogonal projection of the elements (components and conductors) of the low voltage CBT circuit in the plane of the electronic board 1102 extends within the quadrilateral Q. Similarly, "Extending outside the quadrilateral" means that the orthogonal projection of the elements (components and conductors) of the primary circuits CPa, CPb operating at high voltage in the plane of the electronic board 1102 is outside the quadrilateral Q.

[0075] To obtain low inductance in each loop, at least one capacitive element of the capacitor Cour, preferably all the capacitive elements, is located, for example, in the quadrilateral Q. Thus, the capacitive elements are as close as possible to both secondary coils, and in particular to their terminals, simultaneously. Furthermore, at least one of the terminals Sla, S2a, Ma, Slb, S2b, Mb of the secondary coil Sa, Sb of the first of the transformers Ta, Tb is separated by no more than 3 cm from at least one of the terminals Sla, S2a, Ma, Slb, S2b, Mb of the secondary coil Sa, Sb of the other of the transformers Ta, Tb. This ensures that the secondary coils Sa, Sb are sufficiently close to each other to allow the output capacitance COut to be close to both of them simultaneously.

[0076] Furthermore, the control circuits CCa, CCb both extend on one side outside the first and second lines L1, L2, which form sides of the quadrilateral Q extending from one transformer Ta, Tb to the other (the control circuits CCa, CCb extend below line L2 in the illustrated example). However, each control circuit CCa, CCb may need to be connected to a component located outside the quadrilateral Q on a different side of lines L1, L2 than the control circuit CCa, CCb (above line L1 in the illustrated example).

[0077] For example, each CCa, CCb control circuit may need to be connected to the switching elements of switch Qla, Qlb or to drivers (not shown) of these switching elements, in order to control these switching elements

[0078] Alternatively, each CCb, CCb control circuit may need to be connected to a current sensor 1108 (for example, to measure a current flowing through the low voltage output 1106) or a temperature sensor 1110 (for example, to measure a temperature of the low voltage output 1106), to receive the measurements from the sensor 1108, 1110.

[0079] To avoid having to pass a connection under the transformers Ta,Tb or through the secondary circuits operating at high voltage, a connection 1202a, 1202b is provided between the control circuit CCa, CCb and each component to which this control circuit CCa, CCb must be connected, this connection 1202a, 1202b passing through the quadrilateral Q through the two lines L1, L2. “Crossing the quadrilateral” means that the orthogonal projection of connection 1202a, 1202b onto the plane of the electronic board 1102 passes through quadrilateral Q. In practice, connection 1202a, 1202b may be formed, at least in part, by an internal layer within the electronic board to pass over or under the traces and / or components of the low-voltage CBT circuit extending into quadrilateral Q, such as the capacitive elements of the output capacitor Cour-

[0080] The 1202a, 1202b connection connects, for example, the microcontroller uCa, uCb to the desired component.

[0081] Thus the connection 1202a, 1202b passes through the low voltage circuit CBT and not the primary circuits CPa, CPb which would have required isolation or a large distance as they operate at high voltage.

[0082] Fig. 12 and Fig. 13 show two other possible arrangements of the transformers Ta, Tb and the quadrilaterals Q that can be defined in this case.

[0083] In conclusion, it should be noted that the invention is not limited to the embodiments described above. It will indeed be apparent to those skilled in the art that various modifications can be made to the embodiments described above, in light of the information just disclosed to them.

[0084] In the detailed presentation of the invention given above, the terms used shall not be interpreted as limiting the invention to the embodiments set forth in this description, but shall be interpreted as including all equivalents which can be foreseen by a person skilled in the art by applying their general knowledge to the implementation of the teaching which has just been disclosed to them.

Claims

Claims

1. DC-DC conversion device (800), comprising: - an electronic card (1102); - first and second DC-DC converters (112a, 112b) each comprising: • a transformer (Ta, Tb) carried by the electronic card (1102), with: - a primary coil (Pa, Pb), - a secondary coil (Sa, Sb), - at least one pin of a first end terminal (Sla, Slb) of the secondary coil (Sa, Sb), and - at least one pin of a second end terminal (S2a, S2b) of the secondary coil (Sa, Sb); • a primary circuit (CPa, CPb) carried by the electronic card (1102) and connected to the primary coil (Pa, Pb) of the transformer (Ta, Tb) and designed to operate at high voltage; • a secondary circuit (CSa, CSb) carried by the electronic card (1102) and connected to the secondary coil (Sa, Sb) of the transformer (Ta, Tb) and designed to operate at low voltage, the secondary circuit (CSa, CSb) comprising at least one switching element; • a control circuit (CCa, CCb) carried by the electronic card (1102) and designed to control the switching element; - a low voltage circuit (CBT) carried by the electronic card (1102) and including at least the secondary circuits (CSa, CSb); characterized in that: - there is a quadrilateral (Q) with four vertices located respectively on the pin of the first end terminal (Sla) of the secondary coil (Sa) of the first transformer (Ta), the pin of the second end terminal (S2a) of the secondary coil (Sa) of the first transformer (Ta), the pin of the first end terminal (Slb) of the coil secondary (Sb) of the second transformer (Tb) and the pin of the second end terminal (S2b) of the secondary coil (Sb) of the second transformer (Tb), the high voltage primary circuits (CPa, CPb) and the primary coils (Pa, Pb) of the transformers (Ta, Tb) extending outside the quadrilateral (Q); - at least one control circuit (CCa, CCb) extending on one side outside first and second lines (Ll, L2) forming sides of the quadrilateral (Q) extending from one transformer (Ta, Tb) to the other; and - the DC-DC conversion device (800) comprises a component located outside the quadrilateral (Q) on the other side of the lines (Ll, L2) than the control circuit (CCa, CCb), as well as a connection (1202a, 1202b) between the control circuit (CCa, CCb) and the component, this connection (1202a, 1202b) crossing the quadrilateral (Q) through the two lines (Ll, L2).

2. The DC-DC conversion device (800) of claim 1, wherein the component is the switching element or a driver of that switching element.

3. DC-DC conversion device (800) according to claim 1, wherein the component is a current or temperature or voltage sensor (1108, 1110) and wherein the connection (1202a, 1202b) is adapted to provide the sensor measurements to the control circuit (CCa, CCb).

4. DC-DC conversion device (800) according to any one of claims 1 to 3 further comprising an output capacitor (Cout) having at least one capacitive element and designed to present between two terminals an output voltage (Vout) of the first and second DC-DC converter (112a, 112b) and in which the low voltage circuit (CBT) comprises in the quadrilateral (Q) said capacitive element.

5. DC-DC conversion device (800) according to any one of claims 1 to 4, wherein the connection (1202a, 1202b) is formed at least in part by an internal layer of the electronic card (1102).

6. A DC-DC conversion device (800) according to any one of claims 1 to 5, wherein the quadrilateral (Q) is a rectangle.

7. DC-DC conversion device (800) according to any one of claims 1 to 6, wherein the control circuits (CCa, CCb) are located on the same side of the quadrilateral (Q).

8. Electrical system comprising: - a first and a second DC voltage source; and - a DC-DC conversion device (800) according to any one of claims 1 to 7, wherein the first DC-DC converter (112a) is connected to the first DC voltage source to receive its input voltage (V1Na) and wherein the second DC-DC converter (112b) is connected to the second DC voltage source to receive its input voltage (V1Nb).

9. Mobility device (100) comprising a DC-DC conversion device (800) according to any one of claims 1 to 7 or an electrical system according to claim 8.

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