WO2018219905A1

WO2018219905A1 - Dc-dc converter for an electric or hybrid vehicle

Info

Publication number: WO2018219905A1
Application number: PCT/EP2018/064003
Authority: WO
Inventors: Larbi Bendani; Jean-Yves Le Gouil
Original assignee: Valeo Siemens Eautomotive France Sas; Apojee Sas
Priority date: 2017-05-29
Filing date: 2018-05-29
Publication date: 2018-12-06
Also published as: FR3066866A1; FR3066866B1

Abstract

The invention relates to an insulated DC-DC converter (10A, 10B), in particular for an electric or hybrid vehicle, comprising a first circuit (PR10) and a second circuit (CV10). The first circuit (PR10) comprises a first switch (Q_HSB), a second switch (Q_LSB) and a third switch (Q_HSB2), a first inductive coil (L_buck1), a second inductive coil L_buck2) and a third inductive coil (L_buck3), the first switch (Q_HSB) and the first inductive coil (L_buck1), firstly, and the third switch (Q_HSB2) and the third inductive coil (L_buck3), secondly, being connected in parallel.

Description

CONTINUOUS-CONTINUOUS CONVERTER FOR ELECTRIC OR HYBRID VEHICLE

TECHNICAL FIELD AND OBJECT OF THE INVENTION [0001] The present invention relates to the field of electric or hybrid vehicles and more particularly relates to a method and a DC voltage converter for an electric or hybrid vehicle.

STATE OF THE ART

As is known, an electric or hybrid motor vehicle comprises an electric drive system powered by a high voltage power supply battery via a high voltage on-board electrical network and a plurality of auxiliary electrical equipment powered by a battery of power ^. low voltage supply via a low voltage on-board electrical network. Thus, the high voltage power supply battery provides a power supply function of the electric drive system for propelling the vehicle. The low-voltage battery pack powers auxiliary electrical equipment, such as on-board computers, window motors, a multimedia system, and so on. The high voltage battery pack typically supplies a voltage of between 100 V and 900 V, preferably 100 V to 500 V, while the battery ^of low voltage power supply typically supplies a voltage of ^the order of 12 V, 24 V or 48 V. These two high and low voltage battery packs must be able to be charged.

The electric power recharge of the high-voltage power supply battery is carried out in a known manner by connecting it, via the high-voltage electrical network of the vehicle, to an external electrical network, for example the domestic alternating electric network. It is also known to charge the low voltage battery directly from the high voltage battery. To this end, the high-voltage battery is connected to the low-voltage battery via a DC voltage converter, commonly called a DC-DC converter.

Such a DC-DC converter comprises, in known manner, a first circuit, also called a pre-regulator, and a second voltage converter circuit, galvanically isolated and whose output voltage supplies the low-voltage electrical network of the vehicle in order, in particular, to recharge the low-voltage battery.

The first circuit makes it possible to deliver an electrical signal to the second circuit, in particular by modifying the duty cycle of the first circuit. The second circuit includes a or a plurality of transformers for converting the input voltage to a lower value output voltage ^for supplying the low voltage electrical network, depending on the current or voltage of the electrical signal delivered by the first circuit.

[0007] An example is shown in Figure 1 of such a DC-DC converter 1 for converting an ^input voltage corresponding to the VHT voltage across the high-voltage supply network by an output voltage VBT, lower value corresponding to the voltage across the network ^of low voltage power supply.

In this example, the first circuit PR1, of the "buck boost" type, and the second circuit CV1 together make it possible to provide a switching power supply. PR1 the first circuit makes it possible to regulate the voltage that is inputted in particular using induction coils while the second CV1 circuitry reduces the voltage thus regulated via one or more ^transformers galvanic isolation.

[0009] In this example, still referring to Figure 1, the first PR1 circuit comprises ^firstly a first ^input terminal E1 H and a second ^input terminal E1 L between which is defined the ^input voltage VHT, the second input terminal E1 L being further connected to a first electrical ground M1. The first PR1 circuit comprises an ^input capacitance C, _n, connected between the first ^input terminal E1 H and the second ^input terminal E1 L, and a first QHSB switch, said switch top side, connected on ^the one hand to the first ^input terminal E1 H and secondly to a first terminal of a first inductive coil Lbucki at ^a point of MB1. The second terminal of the first inductive coil Lbucki is connected to a node S1 of the first circuit PR1.

[001 0] The first PR1 circuit then comprises a second QLSB switch, said low side switch, connected on ^the one hand the first QHSB switch and the first terminal of the first inductive coil Lbucki at the item and MB1 connected else share in the first mass M1.

[001 1] The second circuit CV1 is connected to the first circuit PR1 via the node S1. The second circuit CV1 comprises in particular a first switch QHSFW and a second switch QLSFW whose duty cycle remains constant. In particular, the first switch QHSB and the second switch QLSB of the first circuit PR1 control the output voltage VBT through their variable duty cycle.

With this type of topology, it has been found that the junction temperature of the first switch QHSB of the first circuit PR1 could exceed a critical temperature due to the strong current flowing through the first inductive coil Lbuck-i, thus presenting a risk. damaging said first QHSB switch. This is particularly the case when the circuit operates from a power of 5 kW with a minimum voltage of 170 V.

[0013] The ^invention therefore aims to solve this problem by proposing a simple, reliable and efficient solution for DC-DC converter to avoid exceeding the critical temperature of the first switch QHSB PR1 of the first circuit.

GENERAL PRESENTATION OF THE INVENTION

For this purpose, the invention relates first of all to an isolated DC-DC converter, particularly for an electric or hybrid vehicle, comprising a first circuit and a second circuit.

[0015] The first circuit comprises a first ^input terminal and a second input terminal between which a DC input voltage is intended to be received, a first electrical node and a second electrical node between which is defined a DC voltage , said intermediate voltage (VINT), obtained from the input voltage regulated by the first circuit, a first switch having a first terminal connected to the first input terminal, a first inductive coil connected by a first terminal to a first second terminal of the first switch and a second terminal at the first electrical node, a first capacitance having a first terminal connected to the second terminal of the first switch and the first terminal of the first inductive coil, a second inductive coil having a first terminal , connected to the second terminal of the first capacitor, and a second terminal connected to at the second electrical node, and a second switch having a first terminal, connected to the second terminal of the first capacitor and the first terminal of the second inductive coil, and a second terminal connected to the second input terminal. The second circuit, which is an isolated voltage converter, is connected to the first electrical node and the second electrical node, and comprises a first switch, a second switch, a first capacitor connected between said first switch and said second switch, and a first output terminal and a second output terminal between which a DC output voltage, obtained by converting the intermediate voltage, is to be supplied by the second circuit.

[0017] The DC-DC converter is characterized in that the first circuit further comprises a third switch having a first terminal connected to the first ^input terminal, a third inductive coil connected by a first terminal to a second terminal of the third switch and by a second terminal to the first electrical node, a second capacitor having a first terminal, connected to the second terminal of the third switch and the first terminal of the third inductive coil, and a second terminal connected to the first terminal of the second switch and the first terminal of the second inductive coil. [0018] With the converter according to ^the invention, and in particular with ^the addition of the third inductive coil, each of the first switch and the third switch receives the same current regardless of ^the other, which in particular prevents any of these two switches to receive more current than ^the other. The first switch and the third switch being powered independently, so they can switch at slightly different times, of ^the order ^of a hundred nanoseconds, without it causes high absorption of current by the person who switches to first, current being distributed substantially equally between the two switches. This prevents the critical temperature of the first switch and the third switch from being exceeded, thereby reducing the risk of damaging them. Preferably, the converter comprises a first control system configured to switch the first circuit between a first state, wherein the first switch and the third switch of the first circuit are closed while the second switch of the first circuit is open, and a second state in which the first switch and the third switch of the first circuit are open while the second switch of the first circuit is closed.

[0020] According to one aspect of the invention, the first ^input terminal is for connection to a source ^of supply voltage and the second ^input terminal is for connection to a first electrical ground.

[0021] Advantageously, the first circuit further comprises an input capacitance, the ^input voltage being defined across said ^input capacitance.

[0022] Preferably, the value of inductance of the first inductive coil and the inductance value of the third inductive coil are equal, in particular in order ^to allow a current of the same intensity to browse simultaneously.

More preferably, the value of the first capacity and the value of the second capacity of the first circuit are equal.

[0024] According to one characteristic of the ^invention, the first of the first circuit control system is configured to switch the first circuit between the first state and the second state with a variable duty cycle. According to another characteristic of the invention, the converter comprises a second control system of the second circuit configured to switch the second circuit at a constant duty cycle.

In a first embodiment, the switches of the first circuit are controlled so as to control the output voltage of the second circuit by regulating the current flowing in the first capacitor of the second circuit.

In a second embodiment, the switches of the first circuit are controlled so as to control the output voltage of the second circuit by regulating the voltage defined across the first capacitor of the second circuit. [0028] In one aspect of ^the invention, the second circuit includes a magnetic component and succession ^of opening and closing of the switches of the first circuit and the switches of the second circuit are used to convert the ^input voltage into the voltage output via said magnetic component.

[0029] Advantageously, the magnetic component comprises at least one primary circuit and at least a secondary circuit separated by a barrier ^of electrically insulating, said magnetic component being configured to, when the conversion ^of an input voltage of the DC -continued in an output voltage, operate as a transformer from the primary circuit to the secondary circuit and as an impedance that stores energy at the primary circuit. Advantageously, the magnetic component is configured so that, on a first portion of an operating period of the converter, a first portion of the primary circuit transfers energy to a first portion of the secondary circuit and a second portion of the primary circuit. directs inductor storing ^energy, and a second portion of the operating period of the converter, the second part of the primary circuit transfers energy to a second portion of the secondary circuit, and the first part of the primary circuit directs inductance storing Energy.

Advantageously, the magnetic component comprises at least a first transformer and a second transformer in series in which the primary windings of the first transformer form the first part of the primary circuit and the secondary winding of the first transformer forms the first part of the secondary circuit and the primary windings of the second transformer form the second part of the primary circuit and ^the secondary winding of the second transformer form the second part of the secondary circuit. [0032] The invention finally relates to an electric or hybrid vehicle comprising an electric drive system powered by a high voltage battery pack via an embedded high-voltage electrical network, a plurality ^of auxiliary electrical equipment powered by a battery pack low voltage via a low voltage on-board electrical network, and a DC-DC converter as presented previously connected ^{on the} one hand to the high voltage on-board electrical network and on the other hand to the low voltage on-board electrical network.

PRESENTATION OF THE FIGURES [0033] The ^invention will be better understood from reading the description which follows, given by way ^of example and with reference to the accompanying drawings given as ^non-limiting examples in which identical references are given to like objects and wherein: Figure 1 (already commented part) illustrates a first embodiment of a DC-DC converter of ^the prior art,

2 illustrates a first embodiment ^of a DC-DC converter according to ^the invention,

3 illustrates a second embodiment ^of a DC-DC converter according to the invention.

[0034] Note that the figures expose ^the invention in detail to implement the ^invention, said figures can of course be used to better define the invention if necessary.

DETAILED DESCRIPTION OF THE INVENTION

In the description to be made hereinafter, we will speak of an electric or hybrid motor vehicle.

[0036] The vehicle includes a high voltage power battery, an electric drive system, an on-board high voltage electrical network, a battery ^of low voltage power supply, an on-board low voltage electrical network and a plurality ^of auxiliary electrical equipment.

[0037] The onboard high voltage electrical network connects the battery ^to high voltage supply and the electric drive system so that the high voltage power supply battery ensures power supply according to the electric drive system the propulsion of the vehicle. The high voltage power supply battery typically delivers a voltage of between 100 V and 900 V, preferably between 100 V and 500 V.

[0038] The on-board low voltage electrical network connects the battery ^low voltage supply and the plurality of auxiliary electrical devices so that the battery ^low voltage power supply powers the ancillary electrical equipment, such as on-board computers, motors of up screens, a multimedia system, etc. The battery ^low voltage supply typically supplies a voltage of about 12 V, 24 V or 48 V.

The electric power recharge of the high-voltage power supply battery is achieved by connecting it, via a continuous high-voltage electrical network of the vehicle, to an external electrical network, for example the domestic alternative electric network.

The charging of the low voltage battery is performed directly from the high voltage battery. To this end, the high-voltage battery is connected to the low-voltage battery via a DC voltage converter, commonly called a DC-DC converter.

[0041] There is shown in Figures 2 and 3 two embodiments 10A and 10B of DC-DC converter according to ^the invention.

The voltage converter 10A, 10B is a DC-DC converter intended to receive a continuous VHT input voltage and to deliver a continuous VBT output voltage according to a global conversion factor A:

[0043] The ^voltage VHT input, known as "high voltage" is the voltage ^of the network of high voltage supply. This input voltage VHT is for example between 100 and 900 V, preferably between 100 and 500 V. The output voltage VBT, called "low voltage" is the voltage delivered to the low voltage electrical network of the vehicle. This VHT input voltage may for example be of ^the order of 12 V, 24 V or 48 V.

[0044] The DC-DC converter 10A, 10B includes a first circuit PR10, also called pre-regulator, receiving as input the ^voltage VHT input, and a second circuit CV10, which is a voltage converter galvanically isolated and whose output voltage VBT supplies the low-voltage electrical network of the vehicle, in particular to recharge the low-voltage battery. The first circuit PR10 fulfills a pre-regulation function. More precisely, the first circuit PR10 makes it possible to control the input voltage of the second circuit CV10, in particular by correcting the duty cycle of its switches.

[0046] In the examples illustrated in Figures 2 and 3, the first PR10 circuit is of type "buck boost" in order to realize a switching power supply by supplying an intermediate voltage VINT based on the ^voltage VHT input including using coils induction.

The first circuit PR10 is intended to receive the input voltage VHT and to supply the intermediate voltage VINT to the second circuit CV10 according to a first conversion factor Ai:

The first circuit PR10 is an up / down converter, which means that the factor Ai may be less than, equal to or greater than 1.

The first circuit PR10 firstly comprises a first input terminal E1 H and a second input terminal E1 L. The first input terminal E1 H is intended to be connected to the positive pole of the battery. high voltage power supply (not shown). The second ^input terminal E1 L is intended to be connected to a first electrical mass Mi. An input capacitance Cm is connected between the first input terminal E1 H and the second input terminal E1 L, the VHT input voltage being defined between the first ^input terminal E1 H and the second terminal of input E1 L, across said input capacitance C, _n . Preferably, the first electric mass Mi is isolated.

[0050] The first PR10 circuit comprises a first QHSB switch, a first terminal is connected to the first ^input terminal E1 H, a first inductive coil Lbucki connected by a first terminal to a second terminal of the first QHSB switch level a point MB1 and a second terminal at a first node S1 H of the first circuit PR10, a first capacitor C having a first terminal connected to the second terminal of the first switch QHSB and to the first terminal of the first inductive coil Lbucki at from point MB1.

The first circuit PR10 comprises a second inductive coil Lbuck2 having a first terminal connected to the second terminal of the first capacitance Cn at a point MB2 and a second terminal connected to a second node S1 L of the first circuit CV10. .

The first circuit PR10 comprises a second switch QLSB connected, ^{on the} one hand, to the second terminal of the first capacitor Cn and to the first terminal of the second inductive coil Uuckz at the point MB2 and secondly at the second input terminal E1 L (and the first mass Mi electric).

[0053] According to ^the invention, the first PR10 circuit further comprises a third QHSB2 switch of the same type as the first QHSB switch, a first terminal is connected to the first ^input terminal E1 H, a third Lb inductive coil _CPU k3 connected by a first terminal to a second terminal of the third switch QHSB2 at a point MB3 and a second terminal at the first node S1 H, a second capacitor C12 having a first terminal connected to both the second terminal of the third switch QHSB2 and the first terminal of the third inductive coil L _UC k3 at the point MB3, and a second terminal connected to the first terminal of the second switch QLSB and the first terminal of the second inductive coil Lbuck2 at the point MB2.

It could have been considered to connect the third switch QHSB2 between the first input terminal E1 H and the first inductive coil Uucki (ie in parallel with the first switch QHSB). However, in practice, the first switch QHSB and third QHSB2 switch with low respective parasitic inductances but slightly different, the flow of current through the first inductive coil l_b _UA ki trigger the switching of ^the switch, from the first QHSB switch and the third switch QHSB2, whose parasitic inductance is the strongest slightly before the switching of the other switch, from respectively the third switch QHSB2 and the first switch QHSB. Such a trigger would then lead the majority of the current to go through ^the switch that would have switched first, the latter to dissipate high power, resulting ⁱⁿ a share of the losses ^of important energy and ^secondly a reduction in lifetime of said switch, or even its damage.

The DC-DC converter 10A, 10B comprises a first control system 1 10 designed to control the first switch QHSB, the second switch QLSB and the third switch QHSB2 to switch the first circuit PR10 between a first state where the first switch QHSB and the third switch QHSB2 are closed while the second switch QLSB is open, and a second state where the first switch QHSB and the third switch QHSB2 are open while the second switch QLSB is closed. The first control system 1 10 is designed to switch the first circuit PR10 to a first switching frequency F1 corresponding to a first period.

T1: During each period T1, the two states follow one another according to a first duty cycle ai. Thus, the first state is maintained for a time (in x T1), while the second state is maintained for a time (1 -ai) x T1. As will be explained later, the conversion factor Ai depends on the duty cycle a1. In the example described, the conversion factor Ai is substantially:

A - ^Œ

' ^~ (i - ¾)

The first control system 1 10 is further designed to receive a reference voltage and to measure the output voltage VBT. The first control system 1 10 is further adapted to change the duty cycle ai so that the output voltage VBT follows the reference voltage VREF.

[0059] Also in the examples illustrated in Figures 2 and 3, the second CV10 circuit enables to realize a switching power supply by reducing the voltage received from the first circuit PR10 via one or more ^transformers galvanic isolation as will be described hereinafter .

More specifically, the second CV10 circuit is an isolated DC-DC converter that performs a conversion function. The second circuit CV10 is designed to supply the output voltage VBT from the intermediate voltage VINT, according to a first conversion factor Ai: V _S

The second CV10 circuit is a step-down converter, which means that the conversion factor Ai is less than 1. The second circuit CV10 comprises a first capacitor C21, connected between a first node E2H1 and a second node E2L, for smoothing the voltage defined between said first node E2H1 and said second node E2L.

[0063] The second circuit includes a first CV10 QHSFW switch connected on ^the one hand to the first node 1 E2H and also to a third E2H2 node and a second switch QLSFW connected firstly to the second node E2L ^and other hand to the first mass M1 electric.

A high capacity CFWH is connected in parallel with the first switch QHSFW, a low capacity CFWL is connected in parallel with the second switch QLSFW. This high capacity CFWH and this low capacity CFWL allow, during the dead time ^of opening of the first and second switch QHSFW QLSFW switch to achieve zero voltage switching, also called ZVS (Zero Voltage Switching) in English The second circuit CV10 also comprises a second capacitor C22 connected between the third node E2H2 and the first electric ground M1. This second capacity C22 ^ensures a voltage source in the second CV10 circuit. In particular, this second capacitor C22 makes it possible to impose the voltage across the arm formed between the first switch QHSFW and the second switch QLSFW of the second circuit CV10, that is to say across the first capacitor C21.

The second circuit CV10 comprises a magnetic component 130. Notably, this magnetic component 130 comprises a first transformer T and a second transformer T 'for converting the intermediate voltage VINT supplied by the first circuit PR10 into an output voltage VBT of lower value applied to the low voltage electrical network (not shown).

[0067] The second CV10 circuit comprises a first inductive coil LPA connected firstly to the first node E2H 1 and ^secondly to the first processor and T represents ^the leakage inductance at the primary of the first magnetic component 130. The second circuit CV10 comprises a second inductive coil LPB connected on the one hand to the third node E2H2 and ^{on the} other hand to the second transformer T 'which represents the leakage inductance at the second magnetic component primary 130.

[0068] The first and second transformers T, T 'have distances ^galvanic isolation creating a galvanic isolation between the primary and the secondary. Thus, the transformers T, T 'form an insulation barrier dividing the second circuit CV10 into two parts. More specifically, the first and second transformers T, T 'each have three windings: a first primary winding, respectively LAU and LAI T, a second primary winding, respectively LAI2 and LAIZ, and a secondary winding, respectively LA2I and LA2V. Each transformer T, T 'further comprises a respective magnetic core (represented by dashed lines) designed to couple ^{on the} one hand respectively the windings LAU, LAI2, LA2I of the first transformer T between them and ^{on the} other hand the windings LAI T , LAIZ, LA2V of the second transformer T 'between them. It will be noted that the windings LAU, LAI2, LA2I of the first transformer T are decoupled from the windings LAI V, LAI2 ', LA2V of the second transformer T. ^" In particular, in these transformers T, T', the first primary windings have the same polarity and the second primary windings have the same polarity. However, the polarity of the first primary winding is opposite to that of the second primary windings. in general, the coupling coefficient between the windings can be different. in ^the example described for each transformer T, T ^' , the coupling coefficient between the first and second primary windings is 1, and the Coupling coefficient between the secondary winding and each of the first and second primary windings is N. Thus, the first primary windings LAU, LAU 'are disposed in series between the first ^input terminal E2H 1 (via the first inductive coil LPA) and the first mass Mi and the second primary windings LAI2, LAI2' are arranged in series between the third node E2H2 (via the second inductive coil LPB) and the second node E2L.

The second circuit CV10 comprises a third switch QHSS and a fourth switch QLSS respectively connected ^{on the} one hand to the secondary windings LA2I, LA2V and ^{on the} other hand to a second mass M2 electric, different from the first mass M1, this second M2 electrical mass is preferably isolated.

The second circuit CV10 comprises a second control system 120 of the second circuit CV10. This second control system 120 is designed to control the first switch QHSFW, the second switch QLSFW, the third switch QHSS and the fourth switch QLSS to switch the second circuit CV10 between a first state where the first switch QHSFW and the third switch QHSS are closed while the second switch QLSFW and the fourth switch QLSS are open, and a second state where the first switch QHSFW and the third switch QHSS are open while the second switch QLSFW and the fourth switch QLSS are closed.

The second control system 120 is designed to switch the second circuit CV10 to a second duty cycle. The first duty cycle and the second duty cycle can be identical or different. Preferably, they are different. More preferably, the first duty cycle is variable while the second duty cycle is constant.

In the second circuit CV10, during each second modulation period T ₂ , the two states follow one another in a second duty cycle 02. Thus, the first state is maintained for a time (02-12), while the second state is maintained for a time (I -CI2) x T2. As will be explained later, the conversion factor Ai depends on the duty cycle ai. In the example described, the conversion factor Ai is substantially:

A ₂ = 2 ^■ N ^■ a ₂ ^■ (1 - a ₂ ) = ^ L.

^V INT

where N is the conversion coefficient between the secondary winding and each of the primary windings described hereinafter. In ^the example described, the first control system is adapted to switch the second CV10 circuit with a constant duty cycle 02 ratio, preferably equal to 0.5. The second circuit CV10 comprises a first output terminal S2H and a second output terminal S2L for supplying the output voltage Ver to the low voltage supply network. The second output terminal S2L is connected to the second electrical M2 mass. The second circuit CV10 comprises an output capacitor C _or t connected between the first output terminal S2H and the second output terminal S2L in order to smooth the output voltage VBT. It will be noted ^that with the configuration of the second circuit CV10, the capacitor C _or tn ^'is traversed by the current received ^from one of the branches respectively constituted of the first primary windings LAU, LAU' and second LA2I windings LA2V.

A load Z is connected between the first output terminal S2H and the second output terminal S2L to be electrically powered by the output voltage VBT. Load Z represents in this example the network ^of low voltage power supply which is connected to the low supply voltage to recharge battery

In the first embodiment illustrated in FIG. 2, the first node E2H1 of the second circuit CV10 is connected to the first node S1 H of the first circuit PR10 and the second node E2L of the second circuit CV10 is connected to the second node S1 L. the first circuit PR1 0. such an arrangement is called ^"attack current", that is to say that the parameter controlled by the first PR10 circuit is the current flowing in the first capacitor C21, in order to control the intermediate voltage VI T defined across the first capacitor C21 of the second circuit CV10 by regulating current.

In the second embodiment illustrated in FIG. 3, the first node S1 H of the first circuit PR10 is connected to the first ground M1 and the second node S1 L of the first circuit PR10 is connected to the third node E2H2 of the second circuit. CV10. Such an arrangement is called ^"of voltage attack", that is to say that the parameter controlled by the first circuit is the voltage PR10 define the terminals of the capacitor C21, the purpose being to directly control this voltage without controlling while running.

[0079] In these examples, the switches are each in the form of a type of MOSFET (in ^English "Metal Oxide Semiconductor Fieid Effect Transistor"). Alternatively, each of the first switch QHSFW, QLSFW second switch, third switch and fourth QHSS QLSS switch may be formed by another type of transistor (IGBT, or other) or by a diode ^whose condition would be imposed by the state of other controllable switches. Part, especially all, of the DC-DC converter 10A, 10B may be made from a semiconductor material such as silicon (Si), gallium nitride (GaN), silicon carbide (SiC), or any other semiconductor material.

[0081] The converter of the invention thus allows the first Uucki switch, the second switch _CPU Lb k2 and k3 _UC Lb third switch receiving the same current independently of each other, which prevents in particular ^the one at the other of the first switch Uucki or the third switch Lb _UC k3 to receive more current than the others.

[0082] The first switch Lb _UC ki Lb and the third switch K3 _CPU can thus switch at slightly different times because without this absorption of ^the entire current by one that switches first, risking damage. In other words, the current received by the one that switches first is less than the current received by ^all of the two switches after switching.

Claims

1. Isolated DC-DC converter (10A, 10B), particularly for a motor vehicle, comprising:

a first circuit (PR10) comprising:

- a first ^input terminal (E1 H) and a second ^input terminal (E1 L) between which an input voltage (VHT) is continuing to be received,

- a first electrical node (S1 H) and a second electrical node (S1 L) between which is defined a DC voltage, said intermediate voltage (VINT), obtained from the ^input voltage (VHT) controlled by the first circuit (PR10)

a first switch (QHSB) having a first terminal connected to the first input terminal (E1 H), a first inductive coil (Uucki) connected by a first terminal to a second terminal of the first switch (QHSB) and by a second terminal at the first electrical node (S1 H), a first capacitance (C) having a first terminal connected to the second terminal of the first switch (QHSB) and the first terminal of the first inductive coil (Uucki), a second inductive coil ( Lbuck2), having a first terminal, connected to the second terminal of the first capacitance (Cn), and a second terminal connected to the second electrical node (S1 L), and a second switch (QLSB) having a first terminal, connected to the second terminal of the first capacitor (Cn) and to the first terminal of the second inductive coil (Lbuck2), and a second terminal connected to the second ^input terminal (E1 L),

a second circuit (CV10), isolated voltage converter, connected to the first electrical node (S1 H) and to the second electrical node (S1 L) and comprising a first switch (QHSFW), a second switch (QLSFW), a first capacitor (C21) connected between said first switch and said second switch, and a first output terminal (S2H) and a second output terminal (S2L) between which a continuous output voltage (VBT), obtained by converting the intermediate voltage ( VINT), is intended to be supplied by the second circuit (CV10),

the DC-DC converter (10A, 10B) being characterized in that the first circuit (PR10) further comprises a third switch (QHSB2) having a first terminal connected to the first ^input terminal (E1 H), a third coil inductive (Lb _UC k3) connected by a first terminal to a second terminal of the third switch (QHSB2) and a second terminal to the first electrical node (S1 H), a second capacitor (C12) having a first terminal connected to the second terminal of the third switch (QHSB2) and the first terminal of the third inductive coil (Lb _UC k3), and a second terminal connected to the first terminal of the second switch (QLSB) and the first terminal of the second inductive coil (Lb _UC k2).

The DC-DC converter (10A, 10B) according to claim 1, comprising a first control system (1 10) configured to switch the first circuit (PR10) between a first state, wherein the first switch (QHSB) and the third switch (QHSB2) of the first circuit (PR10) are closed while the second switch (QLSB) of the first circuit (PR10) is open, and a second state in which the first switch (QHSB) and the third switch (QHSB2) of the first circuit (PR10) are open while the second switch (QLSB) of the first circuit (PR10) is closed.

3. A DC-DC converter (10A, 10B) according to one of the preceding claims, wherein the inductance value of the first inductive coil (Uucki) and the value ^of inductance of the third inductive coil (Unci) are equal .

4. A DC-DC converter (10A, 10B) according ^to one of the preceding claims, wherein the first control system (1 10) of the first circuit (PR10) is configured to switch the first circuit (PR10) between the first state and the second state at a variable duty cycle.

5. DC-DC converter (10A) according to one of the preceding claims, wherein the switches (QHSB, QHSB2, QLSB) of the first circuit (PR10) are controlled to control the output voltage (VBT) of the second circuit. (CV10) by regulating the current flowing in the first capacitor (C21) of the second circuit (CV10).

6. A DC-DC converter (10B) according ^to one of claims 1 to 4, wherein the switches (QHSB, QHSB2, QLSB) of the first circuit (PR10) are controlled so as to control the output voltage (VBT) of second circuit (CV10) by regulating the voltage defined across the first capacitor (C21) of the second circuit (CV10).

7. DC-DC converter (10A, 10B) according ^to one of the preceding claims, wherein the second circuit (CV10) comprises a magnetic component (130) and wherein the opening succession and closure of switches (QHSB, QHSB2, QLSB) of the first circuit (PR10) and switches (QHSFW, QLSFW) of the second circuit (CV10) are used to convert the ^input voltage (VHT) in the output voltage (VBT) over said magnetic component (130).

8. A DC-DC converter (10A, 10B) according to the preceding claim, wherein the magnetic component (130) comprises at least one primary circuit and at least a secondary circuit separated by a barrier ^of electrically insulating, said magnetic component (130 ) being configured for, when converting an input voltage (VHT) of the DC-DC converter (10A, 10B) to an output voltage (VBT), operate as a transformer from the primary circuit to the secondary circuit and as an impedance that stores energy at the primary circuit.

9. DC-DC converter (10A, 10B) according to the preceding claim, wherein the magnetic component (1 30) is configured so that:

- on a first portion ^of a period of operation of the converter, a first portion (LAU, L.A12) of the primary circuit transfers energy to a first part (U21) of the secondary circuit and a second portion (lauryl, LAI? ) of the primary circuit realizes an inductance storing energy;

- On a second part of the converter operating period, the second part (LAU-, LAI2 ') of the primary circuit transfers energy to a second part (LA2V) of the secondary circuit, and the first part (LAU, L.A12 ) of the primary circuit performs an inductor storing ^energy.

10. DC-DC converter (10A, 10B) according to the preceding claim, wherein the magnetic component (130) comprises at least a first transformer (T) and a second transformer (T) in series in which:

- the primary windings (LAU, L.A12) of the first transformer (T) form the first part of the primary circuit and ^the secondary winding (I_A2I) of the first transformer (T) forms the first part of the secondary circuit;

- the primary windings (LAI T LAI2 ') of the second transformer (T) forming the second part of the primary circuit and ^the secondary winding (l_A2v) of the second transformer (T) forms the second part of the secondary circuit.