ES2934619A1 - DC/DC converter (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

DC/DC converter (1) comprising two input terminals (105, 106), a first capacitor (101), a second capacitor (102), a third capacitor (103), a first, second and third switching cell, a first resonator (311), a second resonator (312), a third resonator (313), a three-phase transformer (400) and a three-phase rectifier (500); the first, second and third capacitor being respectively connected in parallel with the first, second and third switching cell; the first, second and third capacitors being connected in parallel with the input terminals; the first, second and third resonator being respectively connected to an output of the first, second and third switching cell; the first, second and third resonators being connected to input coils of the three-phase transformer; (Machine-translation by Google Translate, not legally binding)

Description

DESCRIPTION

DC/DC converter

TECHNIQUE SECTOR

The invention falls within the technical field of power electronics systems and electrical energy conversion systems, and in particular in electrical energy conversion with galvanic isolation.

BACKGROUND OF THE INVENTION

A DC/DC converter is placed between two ports, the input and the output, with no direct current path between them, in order to generate a low or high output voltage from the input power. The use of galvanic isolation in power conversion is essential in many industries, for safety and high and low profits. Especially when there is the human factor in the interaction with electronic equipment. In transportation applications, the galvanic isolation provided by a transformer allows to isolate the high voltage side of the user, preventing the user from being electrocuted in the event of electrical failures, as well as reducing the possibility of such failures propagating through the systems. . One of the main objectives in these converters is to reduce the total volume of the solution, for which it is commonly used to increase the switching frequency and integrated magnetic solutions.

To solve these situations, among others, full bridge topologies (Full Bridge - FB), resonant converters (especially LLC), double active bridge (Dual Active Bridge - DAB) where the transformers have an input and an output are used. However, when large increases or decreases in voltage are required, the transformer comprises windings with a high number of turns and a magnetic core with a high volume, increasing losses. Additionally, if the input voltage is very high, devices (transistors) capable of withstanding said voltage are required, reducing the catalog of devices and reducing their performance. The use of the insulated gate bipolar transistor, known as IGBT by its English name, supports voltages greater than 10kV, however, metal-oxide-semiconductor field effect transistors, known as MOSFET by its English name, made of silicon they support 1200V and GaN transistors support up to 650V due to technological limitations. To solve this, cells are arranged in series, cascode and multiphase devices.

In the article “Review of High-Frequency High-Voltage-Conversion-Ratio DC-DC Converters” (Y. Guan, C. Cecati, J. M. Alonso and Z. Zhang, IEEE Journal of Emerging and Selected Topics in Industrial Electronics, vol. 2, No. 4, pp. 374-389, Oct. 2021, doi: 10.1109/JESTIE.2021.3051554.) the different existing topologies are analyzed. The authors review transformer-based and coil-coupled converters, detailing the advantages and disadvantages of each converter. However, all topologies incorporate multiple transformers when aiming to achieve high voltage conversion ratios. The authors detail the use of cascade switched devices as an advantage due to lower blocking voltages, as well as allowing more modes of operation by having more switches.

Other authors have explored the use of three-phase DC/DC converters, as in "A ZVZCS three-phase boost dc-dc converter distributing 400VDC in Telco and data centers to improve energy efficiency", R. Verma and S. Gupta, Third International Conference on Computational Intelligence and Information Technology (CIIT 2013), 2013, pp. 598-604, doi: 10.1049/cp.2013.2652. However, these authors use traditional three-phase inverters connected to three separate transformers.

Isolated DC/DC converters often have low power densities at high power, mainly due to the bulk of the transformer, as there are frequency step-up limits to avoid other problems. One solution to the volume problem is the use of matrix transformers, where there are multiple secondaries in parallel with the aim of increasing power without excessive increase in volume. This solution is detailed by the authors in "High-Efficiency High-Power-Density LLC Converter With an Integrated Planar Matrix Transformer for High-Output Current Applications", C. Fei, F. C. Lee and Q. Li, in IEEE Transactions on Industrial Electronics, vol. 64, no. 11, p.

9072-9082, Nov. 2017, doi: 10.1109/TIE.2017.2674599.

GENERAL DESCRIPTION OF THE INVENTION

The present invention tries to solve problems that have state-of-the-art solutions such as those mentioned above.

The present invention relates to a DC/DC converter, that is to say, to a converter that transforms direct current at one direct voltage level into direct current at another direct voltage level. The DC/DC converter has a structure that makes it possible to take advantage of the synergies of the electronic components that make up the converter, such as capacitors with less capacitance, and therefore less volume and weight; switchgear cells subjected to lower voltages, and consequently less dependence on very specific types of switches; a three-phase transformer with a smaller magnetic core and therefore cheaper and less heavy; all this without reducing the conversion ratio of the converter or the effectiveness of the galvanic isolation of the converter. In this way, it is possible to increase the power density supplied by the converter, as well as to decrease the cost of the converter.

A first aspect of the present invention relates to a DC/DC converter, the DC/DC converter comprising two input terminals, a first capacitor, a second capacitor, a third capacitor, a first switching cell, a second switching cell , a third switching cell, a first resonator, a second resonator, a third resonator, a three-phase transformer and a three-phase rectifier; the first capacitor being connected in parallel with the first switching cell; the second capacitor being connected in parallel with the second switching cell; the third capacitor being connected in parallel with the third switching cell; the first capacitor, the second capacitor and the third capacitor being connected in parallel with the two input terminals such that a voltage between the two input terminals is equal to a sum of voltages of the first capacitor, the second capacitor and the third capacitor ; an input of the first resonator being connected to an output of the first switching cell; an input of the second resonator being connected to an output of the second switching cell; an input of the third resonator being connected to an output of the third switching cell; the three-phase transformer comprising three input coils; a first resonator output, a second resonator output and a third resonator output being connected to the input coils; and the three-phase rectifier being connected to three output coils of the three-phase transformer.

The commutation cells allow to vary a sign of electrical current supplied to the resonators, such that the commutation cells allow alternating current to be generated from direct current. The DC/DC converter may comprise processing means configured to send control signals to the switching cells such that, by connecting the input terminals to a direct voltage, an alternating current is generated at the output of each switching cell.

The resonators are configured to amplify currents of one or more specific frequencies, so that they supply three-phase current to three primary windings, in other words, to three input windings of the three-phase transformer.

In this way, the set formed by the first, the second and the third capacitor, the first, the second and the third commutation cell and the first, the second and the third resonator is a triphasic inverter, in other words, a inverter configured to convert direct current from the input terminals into three-phase current at the outputs of the resonators.

The connections between the resonators and the three-phase transformer allow three-phase output current from the resonators to be supplied to the three-phase transformer, more specifically, supplied to the three input windings of the three-phase transformer.

The three-phase rectifier enables a three-phase current supplied to the three-phase rectifier to be converted into a direct current at an output of the three-phase rectifier. The connections between the three-phase rectifier and the three output windings of the three-phase transformer allow a three-phase current from the three output windings of the three-phase transformer to be converted into a direct current at an output of the three-phase rectifier.

Using several capacitors in parallel with the input terminals of the DC/DC converter allows a volume of the capacitors to be reduced because it allows the capacitors to store less energy as compared to a single capacitor in parallel with the input terminals. Additionally and synergistically, each commutation cell blocks a lower voltage, thanks to the cascade commutation cell structure, allowing the use of switches with less tolerance to high voltage blocking, as well as less wear on the commutation cells. A uniform distribution of the input voltage between the switching cells allows each switching cell to supply the same power.

The use of a resonant tank formed by the resonators allows a generation of alternating currents, approximately sinusoidal, by applying resonance to pulsed voltages from the switching cell outputs so that said alternating currents are supplied to the transformer primaries. These alternating currents are transformed by the transformation ratio and induced in the secondary of the transformer, where they are rectified by the three-phase rectifier. The use of three interlocked phases smoothes the pulsating character of the power delivered to the output of the converter, reducing a capacitance of a capacitor to decrease a ripple of an output voltage output from the converter. Each resonator can comprise a first inductance and a first capacitance connected in series such that a resonant frequency of the resonator coincides with a frequency of a first harmonic of the modulated voltage at the output of the switching cell connected to the resonator, and can optionally comprising a second inductance and a second capacitance connected in series with each other whose resonant frequency is a frequency of a third harmonic of the modulated voltage at the output of the switching cell connected to the resonator; the second inductance and capacitance being connected in parallel with the first inductance and capacitance. Resonators can be more complex, allowing, for example, higher frequency harmonics to be amplified. Thanks to the use of additional harmonics to the fundamental, the voltage supplied to the transformer is increased and therefore the power transmitted by the transformer increases.

The configuration of each switching cell allows the resonator input to be connected successively to each of the two terminals of the capacitor, the capacitor being in parallel with the switching cell, and the resonator input being connected to the output of the switching cell .

In some embodiments, the DC/DC converter may comprise processing means configured to send control signals to the switching cells such that the switching frequency of the three switching cells matches a resonant frequency of the three resonators.

For use as a voltage reducer, a three-phase star-delta transformer can be used, allowing a ratio of turns of the three-phase transformer to be lower compared to its star-star equivalent, since the line voltage is multiplied by V3, obtaining the voltage of output given by the following expression:

Being n the ratio of turns of the primary of the transformer with respect to the secondary of the transformer, VI an input voltage of the transformer and Vo an output voltage of the transformer.

For the regulation of the converter, control signals can be applied to each switching cell to complementaryly switch a first cell switching device and a second cell switching device. The output voltage of each switching cell can be controlled by the switching frequency, allowing the gain of the resonant tank to be controlled. The control signals can have a square voltage.

The presence of resonant currents makes it possible to reduce the switching losses of the converter, since resonant currents can be used to discharge the parasitic capacitances of the switches. To this end, the operating frequency can be chosen so that the equivalent load from the switching cells is inductive, being able to apply zero voltage switching, known in English as "Zero Voltage Switching" or by its acronym "ZVS", in switching devices, minimizing switching losses.

In some embodiments, the first switch cell comprises two switches; the output of the first switching cell being connected to the two switches such that in a state in which either one of the two switches is closed and another switch of the two switches is open, an electric circuit is closed, the electric circuit comprising the switch closed and the first resonator.

In some embodiments, at least one of the switches is a transistor. Transistors can behave like switches allowing adaptive and versatile control.

In some embodiments, the at least one transistor is a metal oxide semiconductor field effect transistor.

In some embodiments, the at least one transistor is a high electron mobility transistor.

The distribution of the input voltage among several switching cells allows the blocking voltage of the switches to be reduced, enabling the use of transistors that do not support high blocking voltages, such as metal-oxide-semiconductor field-effect transistors or transistors high electron mobility.

The reluctance of a longitudinal portion of the magnetic core can be calculated as:

he

R = - _M --- ₀ -- _' - _M -- _r -- _■ - _S r

where:

R: is the reluctance of the longitudinal portion,

l: is the length of the longitudinal portion,

M0: is the magnetic permeability of the vacuum,

Mr : is the relative magnetic permeability of the longitudinal portion and

S: is a total area of the cross section of the longitudinal portion.

In some embodiments, the three-phase transformer comprises a magnetic core; a first longitudinal portion of the magnetic core having a cross section with a total area less than the total area of a cross section of a second longitudinal portion of the magnetic core; the three-phase transformer being configured so that, when feeding the three input coils with three-phase current, a magnetic flux generated by the three-phase transformer in the first portion is zero without individual magnetic fluxes generated in the first portion by coils of the three-phase transformer being zero .

The individual magnetic fluxes are: the magnetic flux generated by the first input coil of the transformer, the magnetic flux generated by the second input coil of the transformer, the magnetic flux generated by the third input coil of the transformer, the magnetic flux generated by the first output coil of the transformer, the magnetic flux generated by the second output coil of the transformer, and the magnetic flux generated by the third output coil of the transformer.

As the magnetic flux generated by the transformer coils and passing through the section of the first portion is null, the total area of the required section is less than in other converters in which the flux is not zero, allowing the size and converter weight.

In some embodiments, the total cross-sectional area of the first longitudinal portion is zero. The null total area implies a maximum minimization of the size of said section and with it the weight and size of the first portion.

In some embodiments, the DC/DC converter comprises an output capacitor for decreasing a ripple of a three-phase rectifier output voltage, the output capacitor being connected to an output of the three-phase rectifier. In general, output voltage ripple is detrimental to loads connected to the converter. The output capacitor allows to reduce this ripple.

The different aspects and embodiments of the invention defined above can be combined with each other, as long as they are mutually compatible.

Additional advantages and features of the invention will become apparent from the following detailed description and will be pointed out with particularity in the appended claims.

BRIEF DESCRIPTION OF THE FIGURES

In order to help a better understanding of the characteristics of the invention according to examples of practical embodiments of the same, a set of drawings is attached as an integral part of the description, in which, for illustrative purposes, what has been represented has been following:

Figure 1 schematically shows a DC/DC converter according to some embodiments of the invention, the converter being connected to various power sources and various loads.

Figure 2 schematically shows a DC/DC converter according to some embodiments of the invention, the DC/DC converter being connected to a DC voltage source.

Figure 3 shows capacitor connections with switching cells of DC/DC converters according to some embodiments of the invention.

Figure 4 shows portions of three-phase rectifiers of DC/DC converters according to some embodiments of the invention.

Figure 5 shows resonators of a DC/DC converter according to some embodiments of the invention.

Figure 6 schematically shows a three-phase transformer of a DC/DC converter according to some embodiments of the invention.

Figure 7 shows switching signals from switching cells of a DC/DC converter according to some embodiments of the invention.

Figure 8 shows switching signals from switching cells of a DC/DC converter according to some embodiments of the invention, and shows currents resulting from said switching signals.

Figure 9 shows switching signals from switching cells of a DC/DC converter according to some embodiments of the invention, and shows currents resulting from said switching signals.

Figure 10 shows average voltages in resonators of a DC/DC converter according to some embodiments of the invention.

Figure 11 shows a DC/DC converter according to some embodiments of the invention, the converter being connected to a DC voltage source.

Fig. 12 shows a graph of a relationship between gain and frequency of a resonator of a DC/DC converter according to some embodiments of the invention. Specifically, Figure 12 shows a voltage gain curve for each resonator.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

In view of this description and figures, the person skilled in the art will be able to understand that the invention has been described according to some preferred embodiments thereof, but that multiple variations can be introduced in said preferred embodiments, without departing from the object of the invention as such. and as it has been claimed.

Figure 1 shows a DC/DC converter (1) with galvanic isolation. The DC/DC converter (1) comprises a three-phase transformer (400), for example, in a star-delta configuration or in a star-star configuration, which allows the magnetic flux of the three-phase transformer (400) in one or several portions of a magnetic core of the three-phase transformer (400) is zero, allowing the size and weight of the three-phase transformer (400) to be reduced, and with it the size and weight of the DC/DC converter (1). In addition, as a magnetic flux of the magnetic core is reduced, magnetic losses in the magnetic core of the transformer are reduced, allowing the reduction/increase factor of the three-phase transformer to be increased without the need to increase a size of the magnetic core and without the need to increase a voltage. supply of primary windings of the three-phase transformer (400). In addition, a distribution of the input voltage in several capacitors allows to reduce the size and weight of the capacitors and to expand the variety of switching cells that can be used in the DC/DC converter (1). For this reason, the DC/DC converter (1) allows minimizing the volume, weight and voltage required to achieve a high conversion factor, in other words, a high direct voltage reduction/increase factor in direct voltage, maintaining effective galvanic isolation.

The DC/DC converter (1) has two input terminals connected in parallel to an electric power generator, a battery, and a fuel cell. The DC/DC converter (1) has two output terminals connected in parallel to a capacitor bank and two loads.

Figure 2 shows the DC/DC converter (1) connected to a direct voltage source V ⁱ (104). Specifically, the DC/DC converter (1) comprises two input terminals (105), (106) connected to the direct voltage source V ⁱ (104). A first capacitor (101), a second capacitor (102) and a third capacitor (103) are connected in parallel with the two input terminals (105), (106) so that a voltage between the two input terminals (105) ), (106) is equal to a sum of voltages of the first capacitor (101), of the second capacitor (102) and the third capacitor (103). In other words, the switching cells are connected in cascade with the two input terminals (105), (106). In this configuration, the sum of the voltages of the first capacitor (101), of the second capacitor (102) and of the third capacitor (103) is equal to the voltage between the two input terminals (105), (106) regardless of the state of the switching cells. Figure 2 shows a first set (100) of direct voltage source V ⁱ (104), first capacitor (101), second capacitor (102) and third capacitor (103).

The first capacitor (101) is connected in parallel with a first switching cell. The first switch cell comprises a first switch (201) and a second switch (202). The first switch (201) is connected to one terminal of the first capacitor (101), and the second switch (202) is connected to another terminal of the first capacitor (101). The second capacitor (102) is connected in parallel with a second switching cell. The second switch cell comprises a third switch (203) and a fourth switch (204). The third switch (203) is connected to one terminal of the second capacitor (102), and the fourth switch (204) is connected to another terminal of the second capacitor (102). The third capacitor (103) is connected in parallel with a third switching cell. The third switch cell comprises a fifth switch (205) and a sixth switch (206). The fifth switch (205) is connected to one terminal of the third capacitor (103), and the sixth switch (206) is connected to another terminal of the third capacitor (103). Figure 2 shows a second set (200) of switching cells. Figure 3 shows examples of these parallel connections between capacitor and switches.

Figure 3 shows examples of parallel connection of the first capacitor (101) with the first switching cell. The parallel connection comprises a first connection (111), a second connection (112) and a third connection (113), the first connection (111) being for connection to the first terminal (105) and the second connection (112) being for connection with the second condenser (102). The third connection (113) is connected between the switches (121), (122), so that when opening one of the switches (121), (122) and closing the other of the switches (121), (122), The third connection (113) remains connected in series with the other of the switches (121), (122). As illustrated in the parallel connection examples in figure 3, the switches can be: metal-oxide-semiconductor junction field effect transistors, insulated gate bipolar transistors, junction bipolar transistors, high electronic mobility transistors, cascodes based on junction field effect transistors and/or cascodes based on high electronic mobility transistors.

Although the connections in Figure 3 represent the parallel connection of the first capacitor (101) with the first switching cell, these parallel connections can be the same for the second capacitor (102) and/or for the third capacitor (103). as can be deduced from figure 11.

Continuing with Figure 2, the DC/DC converter (1) comprises a resonant tank (300) and a three-phase transformer (400), the resonant tank (300) comprising a first resonator, a second resonator and a third resonator. The resonant tank (300) comprises a fourth connection (301) with the third connection (113) of the first switching cell, the fourth connection (301) connecting the first resonator with the first switching cell. The resonant tank (300) comprises a fifth connection (302) of an output of the second switching cell with the second resonator. The resonant tank (300) comprises a sixth connection (303) of an output of the third switching cell with the third resonator.

Figure 5 shows examples of resonators of the resonant tank (300), specifically it shows resonators formed by an LC branch or several LC branches connected in parallel. The second resonator and/or the third resonator can be the same as the first resonator, as can be deduced from figure 11. Figure 11 shows a first resonator (311), a second resonator (312) and a third resonator (313). .

Continuing with figures 2 and 5, the resonant tank (300) comprises a seventh connection (401) of the first resonator with the three-phase transformer (400). Continuing with figure 2, the resonant tank (300) comprises an eighth connection (402) of the second resonator with the three-phase transformer (400) and a ninth connection (403) of the third resonator with the three-phase transformer (400).

Figure 6 shows an electronic diagram of the three-phase transformer (400) in a star-delta configuration. The primary and secondary coils of the three-phase transformer are wound to the same magnetic core of the three-phase transformer. The three-phase transformer (400) comprises three input connections (411), (412), (413). Each of the three input connections (411), (412), (413) is connected in series with one of the seventh connection (401), the eighth connection (402) and the ninth connection (403), as shown. can be deduced, for example, from figure 11. The electronic diagram of the three-phase transformer (400) comprises a leakage inductance (451), (452), (453) and a magnetization inductance (431), (432), ( 433) for each pair of coils (441), (442), (443) of the three-phase transformer (400). The three-phase transformer (400) has three output connections (421), (422), (423).

Continuing with figure 2, the DC/DC converter (1) comprises a three-phase rectifier (500). The three-phase rectifier (500) comprises a tenth connection (501), an eleventh connection (502) and a twelfth connection (503). Each of the tenth connection (501), eleventh connection (502) and twelfth connection (503) is connected to one of the three output connections (421), (422), (423) of the three-phase transformer (400).

Figure 4 shows examples of a first portion of the three-phase rectifier (500). The first portion of the three-phase rectifier (500) comprises the tenth connection (501) connected to the output connection (421) of the three-phase transformer (400). The first portion of the three-phase rectifier (500) comprises output terminals (601), (602) and rectification devices (531), (532). As illustrated in the configurations in Figure 4, the rectifying devices (531), (532) can be: diodes, metal-oxide-semiconductor junction field effect transistors, insulated gate bipolar transistors, junction bipolar transistors, transistors high electronic mobility, cascodes based on junction field effect transistors and cascodes based on high electronic mobility transistors.

Logically, three of these portions of the three-phase rectifier (500) can be connected in cascade to form the three-phase rectifier (500) as can be deduced from figure 11, connecting the input connection of each portion to a different output connection of the transformer. triphasic (400).

Continuing with figure 2, the output terminals (601), (602) are output terminals of the DC/DC converter (1). Figure 2 shows a third set (600) comprising output terminals (601), (602).

Figure 7 shows control signals of the switches of the switching cells of the DC/DC converter (1), the control signals being switching signals. Specifically, Figure 7 shows a first control signal (Sm) of the first switch (201), a second control signal (Su) of the second switch (202), a third control signal (S ^h2 ) of the third switch ( 203), a fourth control signal (S ^l2 ) of the fourth switch (204), a fifth control signal (S ^h3 ) of the fifth switch (205) and a sixth control signal (S ^l3 ) of the sixth switch (206). . Each of these control signals is high for one half of a signal period and low for another half of the period. The period of these control signals is 2n radians, that is, three hundred and sixty degrees.

The second control signal (Su) is pi radians out of phase with respect to the first control signal (S ^h1 ). The fourth control signal (S ^l2 ) is pi radians out of phase with respect to the third control signal (S ^h2 ). The sixth control signal (S ^l3 ) is pi radians out of phase with respect to the fifth control signal (S ^h3 ). The third control signal (S ^h2 ) is late one hundred and twenty degrees from the first control signal (S ^hi ). The fifth control signal (S ^h3 ) is one hundred and twenty degrees behind the third control signal (S ^h2 ).

When the first switch (201) is open, the second switch (202) is closed, so current flows through the second switch (202) and no current flows through the first switch (201). When the first switch (201) is closed, the second switch (202) is open, so current flows through the first switch (201) and no current flows through the second switch (202). Thus, positive and negative currents are generated in the first resonator of the resonant tank (300). Similarly, positive and negative currents are generated in the second resonator of the resonant tank (300) and in the third resonator of the resonant tank (300). Switching cells can be half-bridge.

A level change of a control signal of a switch changes a state of the switch.

As illustrated in Figure 8, three-phase currents are generated in the three resonators of the resonant tank (300). In order to minimize energy consumption, it is advantageous for the switches to change level at the instant in which the three-phase current flowing through the switch is close to zero amps and, for example, zero. These examples are illustrated in Figure 9, which shows that the control signals of two switches in a switchgear change level when the current through one of these switches is close to zero amps. The unit of the abscissa axis of figure 8 is the second. The unit of the blocking voltage in figure 9 is the volt.

In particular, the resonant tank (300) is configured at a resonant frequency such that the resonant tank (300) amplifies current at said resonant frequency.

Figure 10 represents average voltages in the resonators of the resonant tank (300). The voltage of the upper cell is the voltage of the first resonator. The intermediate cell voltage is the second resonator voltage. The voltage of the lower cell is the voltage of the third resonator.

By supplying a direct voltage to the input terminals (105), (106), the input windings of the three-phase transformer (400), in other words, the primary windings of the three-phase transformer (400), are supplied with a three-phase current. , generating a three-phase current in the output coils of the three-phase transformer (400). The output windings of the three-phase transformer (400) are also known as the secondary windings of the three-phase transformer (400).

The three-phase current generated in the secondary windings is rectified by the three-phase rectifier (500), for example, by a suitable actuation of the three-phase rectifier switches (500), allowing a substantially continuous voltage to be generated between the output terminals (601), (602). Logically, the three-phase rectifier (500) can be active or passive.

A capacitor connected to the output terminals (601), (602) makes it possible to decrease a voltage ripple between the output terminals (601), (602).

Example: Isolated converter to power a device in a car.

The present invention can be used in an electric car, comprising a high voltage battery, eg 400V, which is used to power all on-board circuitry. A load that requires low voltages, for example, 12V, can be safely connected to the battery by means of the proposed invention, since the user's safety is guaranteed through isolation, and the voltage conversion occurs in a reduced space suitable for applications with strong volume limitations.

Example: Isolated converter to power computing units in a data center.

The present invention can be used in a data center, which frequently includes a first stage connected to the network that interacts with it, and subsequently distributes a high voltage bus, for example, 450V, which is used to power the systems. . Equipment in a data center typically requires low voltages, eg 48V or 12V, so a buck converter is needed capable of providing high voltage isolation. Reducing the size of these converters reduces the space occupied by the power systems, allowing a higher power density in the same installation.

In this text, the term "comprises" and its variants (such as "comprising", etc.) should not be understood in an exclusive way, that is, they exclude the possibility that what is described includes other elements, steps, etc.

On the other hand, the invention is not limited to the concrete embodiments that have been described but also covers, for example, the variants that can be made by the average person skilled in the art (for example, regarding the choice of materials, dimensions , components, configuration, etc.), within what is apparent from the claims.

Claims (8)

1. DC/DC converter (1), the DC/DC converter (1) comprising two input terminals (105, 106), a first capacitor (101), a second capacitor (102), a third capacitor (103), a first switching cell, a second switching cell, a third switching cell, a first resonator (311), a second resonator (312), a third resonator (313), a three-phase transformer (400) and a three-phase rectifier ( 500); the first capacitor (101) being connected in parallel with the first switching cell; the second capacitor (102) being connected in parallel with the second switching cell; the third capacitor (103) being connected in parallel with the third switching cell; the first capacitor (101), the second capacitor (102) and the third capacitor (103) being connected in parallel with the two input terminals (105, 106) so that a voltage between the two input terminals (105, 106 ) is equal to a sum of the voltages of the first capacitor (101), of the second capacitor (102) and of the third capacitor (103); an input of the first resonator (311) being connected to an output of the first switching cell; an input of the second resonator (312) being connected to an output of the second switching cell; an input of the third resonator (313) being connected to an output of the third switching cell; the three-phase transformer (400) comprising three input coils; a first resonator output (311), a second resonator output (312) and a third resonator output (313) being connected to the input coils; and the three-phase rectifier (500) being connected to three output coils of the three-phase transformer (400). The DC/DC converter (1) of claim 1, the first switching cell comprising two switches; the output of the first switching cell being connected to the two switches such that in a state in which either one of the two switches is closed and another switch of the two switches is open, an electric circuit is closed, the electric circuit comprising the switch closed and the first resonator. The DC/DC converter of claim 2, wherein at least one of the switches is a transistor. The DC/DC converter of claim 3, wherein the at least one transistor is a metal-oxide-semiconductor field-effect transistor. The DC/DC converter of claim 3, wherein the at least one transistor is a high electron mobility transistor. The DC/DC converter of any one of the preceding claims, the three-phase transformer (400) comprising a magnetic core; a first longitudinal portion of the magnetic core having a cross section with a total area less than the total area of a cross section of a second longitudinal portion of the magnetic core; the three-phase transformer (400) being configured so that, when feeding the three input coils with three-phase current, a magnetic flux generated by the three-phase transformer in the first portion is zero without individual magnetic fluxes generated in the first portion by coils of the transformer triphasic are null. The DC/DC converter (1) of claim 6, wherein the total cross-sectional area of the first longitudinal portion is zero. 8. The DC/DC converter (1) of any one of the preceding claims, the DC/DC converter (1) comprising an output capacitor to reduce a ripple of an output voltage of the three-phase rectifier (500), the capacitor being output connected to an output of the three-phase rectifier (500).