Switched-mode converter

Abstract

The present description relates to a switched-mode power supply system comprising at least one pair of dual-bridge converters (DAB1, DAB2), wherein: first switching H-bridges of the converters are connected, in parallel or in series, to two terminals (12, 14) for applying a first voltage (Vin), second switching H-bridges of the converters being connected, in parallel or in series, to two terminals (16, 18) for supplying a second voltage (Vout), and the switches of the converters (DAB1; DAB2) are controlled in opposition from one converter to another.

Description

DESCRIPTION TITLE: Switching Converter technical field

[0001] This description relates generally to electronic systems and more specifically to switching converters. Previous technique

[0002] Switching converters are widely used in electronics to convert one voltage to another of a different value (higher or lower) and / or of a different nature (alternating or direct current). Depending on the application, a switching converter can be of the DC-DC type (direct current to direct current), AC-AC type (alternating current to alternating current), DC-AC type (DC to AC), or AC-DC type (alternating current to DC). There are many switching converter topologies that differ particularly in the nature of the galvanic isolation element (coupled inductors, transformers, etc.) and the arrangement of the switching switch(es) (series, single-bridge, double-bridge, H-bridge, etc.).

[0003] Document EP 3 817 207 describes active double-bridge systems for canceling oscillations.

[0004] Document WO 2019 / 158118 describes a power converter with a wide range of DC voltages.

[0005] The CN 112803740 document describes a method and system for soft starting a DC transformer with series inputs and parallel outputs.

[0006] Document WO 2019 / 158567 describes a dual active bridge DC-DC converter with a wide operating range.

[0007] The document "Research on Loss Reduction of Dual Active Bridge Converter Over Wide Load Range for Solid State Transformer Application" by Qingsham Wang et al., 2016 Eleventh International Conference on Ecological Vehicles and Renewable Energies, XP032903389, describes noise reduction techniques for dual active bridge converters.

[0008] The document "Review of de-de converters for multiterminal HVDC transmission networks" by Adam Grain Philip et al., IET POWER ELECTRONICS, IET, UK, XP006055530, describes DC-DC converters for HVDC transmission networks. Summary of the invention

[0009] There is a need to improve existing converters.

[0010] There is a need for a DC-DC switching converter that allows operation at high switching frequencies.

[0011] There is a need for a switching converter that generates low electromagnetic interference.

[0012] One embodiment overcomes all or part of the disadvantages of known switching converters.

[0013] A switched-mode power supply system comprising: two active double-bridge converters; a first set of switches connecting two input terminals of a first voltage to the two input terminals of each converter or to a single input terminal of each converter; a second set of switches connecting two output terminals of a second voltage to the two output terminals of each converter or to a single output terminal of each converter; and a control circuit for the switches of the first set of switches. and second game, the converter switches being controlled in opposition from one converter to the other.

[0014] According to one embodiment, the switches of the second unit are controlled according to the desired value for the second voltage.

[0015] According to one embodiment, the switches of the first set are controlled according to the power required at output.

[0016] According to one embodiment: a first input terminal of the first converter is connected to a first application terminal of a first voltage and, by means of a first switch of the first set, to a first input terminal of the second converter; a second input terminal of the first converter is connected, by means of a second switch of the first set, to the second application terminal of the first voltage or to the first input terminal of the second converter; a first output terminal of the first converter is connected to a first supply terminal of a second voltage and, by means of a first switch of the second set, to a first output terminal of the second converter; and a second output terminal of the first converter is connected, by means of a second switch of the second set, to a second supply terminal of the second voltage or to the first output terminal of the second converter.

[0017] One embodiment provides a switched-mode power supply system comprising at least one pair of dual-bridge converters, in which: the first H-bridges of the converter switches are connected, in parallel or in series, to two terminals for applying a first voltage, and the second H-bridges of the converter switches... converters being connected, in parallel or in series, to two supply terminals of a second voltage, and the switches of the converters are controlled in opposition from one converter to the other.

[0018] According to one embodiment, each converter comprises: a first H-bridge having a first and a second parallel arm of two switches in series between two input terminals of the converter; a second H-bridge having a third and a fourth parallel arm of two switches in series between two output terminals of the converter; a transformer having a first winding connected to the respective interconnection nodes of the series switches of the first and second arms and having a second winding connected to the respective interconnection nodes of the series switches of the third and fourth arms.

[0019] According to one embodiment, four inductive elements are respectively intercalated between each winding end and the interconnection node to which this end is connected.

[0020] According to one embodiment, said inductive elements all have the same value.

[0021] According to one embodiment, each H-bridge comprises: a first switch and a second switch in series in the first arm; a third switch and a fourth switch in series in the second arm; a fifth switch and a sixth switch in series in the third arm; a seventh switch and an eighth switch in series in the fourth arm.

[0022] According to one embodiment: the first switch of each converter is turned on, respectively blocked, at the same time as the second switch of the other converter; the third switch of each converter is turned on, respectively blocked, at the same time as the fourth switch of the other converter; the fifth switch of each converter is turned on, respectively blocked, at the same time as the sixth switch of the other converter; the seventh switch of each converter is turned on, respectively blocked, at the same time as the eighth switch of the other converter.

[0023] According to one embodiment, the transformation ratio of the transformers of the first and second converters is equal to 1.

[0024] According to one embodiment, the input terminals of the two converters are common or interconnected.

[0025] According to one embodiment, the two output terminals of the two converters are common or interconnected.

[0026] According to one embodiment: a first output terminal of a first converter is connected, preferably connected, to a first supply terminal of the second voltage; a second output terminal of the first converter is connected, preferably connected, to a first output terminal of a second converter; and a second output terminal of the second converter is connected, preferably connected, to a second supply terminal of the second voltage.

[0027] According to one embodiment: a first input terminal of a first converter is connected, preferably connected, to a first application terminal of the first voltage; a second input terminal of the first converter is connected, preferably connected, to a first input terminal of a second converter; and a second input terminal of the second converter is connected, preferably connected, to a second application terminal of the first voltage.

[0028] According to one embodiment, the switches are HEMT-type transistors in GaN technology.

[0029] According to one embodiment, the switches are controlled at a switching frequency of several hundred kHz, preferably greater than 400 kHz.

[0030] According to one embodiment, the system comprises a single pair of converters and the first voltage is supplied by a rectification circuit of a single-phase alternating voltage.

[0031] According to one embodiment, the system comprises three pairs of converters and the first voltage of each converter is extracted from a rectification of a three-phase AC power supply.

[0032] According to one embodiment, the second voltage is intended for charging a battery, preferably a motor vehicle battery. Brief description of the drawings

[0033] These features and advantages, as well as others, will be described in detail in the following description of particular embodiments, given by way of non-limiting example, in relation to the attached figures, among which:

[0034] Figure 1 represents, in a very schematic way, one embodiment of a double active bridge converter;

[0035] Figure 2 represents, in a very schematic way and in block form, one way of implementing a conversion system;

[0036] Figure 3 represents, in a very schematic way, an example of the configuration of the system of Figure 2 in a parallel inputs and parallel outputs connection;

[0037] Figures 4, 5, 6, 7 and 8 illustrate, in the form of chronograms, the operation of a conversion system of the type illustrated in Figure 3;

[0038] Figure 9 represents, in a very schematic way, an example of the configuration of the system of Figure 2 in a parallel inputs and serial outputs connection;

[0039] Figure 10 represents, in a very schematic way, an example of a system configuration of Figure 2 with serial inputs and parallel outputs; and

[0040] Figure 11 represents, in a very schematic way, an example of the configuration of the system of figure 2 in a serial input and serial output connection. Description of the implementation methods

[0041] The same elements have been designated by the same reference numerals in the different figures. In particular, structural and / or functional elements common to the different embodiments may have the same reference numerals and may have identical structural, dimensional and material properties.

[0042] For the sake of clarity, only the steps and elements necessary for understanding the described embodiments have been shown and are detailed. In particular, the control signal generation circuits of the system of The conversion described has not been detailed, as the embodiments described are compatible with the use of standard circuits. Similarly, the equipment connected to the input and output of the described conversion system has not been detailed, as the embodiments described are, again, compatible with the equipment typically connected to the input and output of a switching converter.

[0043] Unless otherwise specified, when referring to two connected elements, this means directly connected without any intermediate elements other than conductors, and when referring to two coupled elements, this means that these two elements can be connected or linked through one or more other elements.

[0044] In the description that follows, when referring to absolute positional qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative positional qualifiers, such as the terms "above", "below", "superior", "inferior", etc., or to orientational qualifiers, such as the terms "horizontal", "vertical", etc., unless otherwise specified, it refers to the orientation of the figures.

[0045] Unless otherwise specified, the expressions "approximately", "roughly", "about", and "on the order of" mean within 10%, preferably within 5%.

[0046] The described embodiments are based on the use of dual active bridge DC-DC switching converters. Such converters consist of two H-bridges with controllable switches, on either side of a transformer, for example associated with filter inductors.

[0047] In such converters, near-zero voltage switching (ZVS) is generally desired; that is, switching the bridge switches from the open to the on state when the voltage across them is zero or nearly zero. This reduces energy losses in the switches. On the other hand, the use of asymmetrical control (the control signals for each leg are not opposed) introduces significant common-mode currents, particularly during the switching of switches connected to the primary and secondary ground sides of the transformer. Such common-mode currents negatively impact converter performance in terms of conducted electromagnetic interference and are more pronounced at higher switching frequencies.This generally leads to limiting the switching frequency to the order of a hundred kHz, thus limiting the compactness of the transformer and inductive filters.

[0048] To reduce electromagnetic interference, switching converters are generally equipped with common-mode filters at both the input and output to minimize conducted noise. Such filters become increasingly bulky and expensive as the power output increases and the frequency to be filtered exceeds certain regulatory thresholds.

[0049] The emergence of high-mobility electron transistors (HEMTs), particularly gallium nitride (GaN), and wide-band gap transistors (WBGTs), which offer high switching performance compared to metal-oxide-semiconductor field-effect transistors (MOSFETs), increases the desire to enhance switching frequencies of switching converters in order to increase the power density of such converters.

[0050] According to the described embodiments, a conversion system is provided comprising two or a multiple of two active double-bridge converters whose inputs and outputs are connected, via sets of switches, to terminals that apply a voltage to be converted and supply a converted voltage. In other words, two active double-bridge converters are used whose inputs and outputs are arranged so that, externally, two input terminals receive the voltage to be converted and two output terminals supply the converted voltage. Furthermore, the switches of one of the converters are controlled in opposition to those of the other converter. This amounts to reversing the transistors in the arms to which identical control signals are applied from one converter to the other.

[0051] The inventors discovered that by combining and controlling two converters in the same conversion system, common-mode noise is significantly reduced, even at high frequencies (several hundred kHz). It's a bit like creating compensation between the noise generated by the two converters.

[0052] Figure 1 represents, in a very schematic way, one embodiment of a DAB active double bridge converter.

[0053] In the example shown, the DAB converter receives a voltage Vin and provides a voltage Vout. The voltages Vin and Vout are, in the use of the converters as described, DC voltages.

[0054] The voltage Vin is applied between two input terminals 12 and 14 and the voltage Vout is supplied between two output terminals 16 and 18.

[0055] The input voltage Vin can be, as will be seen later, a rectified voltage from an AC power source, such as the electrical grid or an alternator. This voltage is applied across a filter capacitor Cin, connected to the input terminals IH and IL of the first H-bridge 21 of the DAB double bridge. In Figure 1, an input impedance Zin between terminals 12 and IH is shown as a dashed line. This impedance represents, for example, the equivalent impedance of the circuits connected upstream of bridge 21.

[0056] The input bridge 21 comprises two parallel arms, or branches, A and B, each having two switches or series switches, respectively K1 and K3, K2 and K4, between terminals IH and IL. The midpoint (interconnection node) between switches K1 and K3 of arm A is connected, for example and optionally by a resistive and / or inductive and / or capacitive (RLC) type impedance, symbolized by its inductance LiH, to a first terminal of a primary winding 23 of a transformer T, the other terminal of which is connected, for example and optionally by an RLC impedance, symbolized by its inductance LiL, to the midpoint (interconnection node) between switches K2 and K4 of arm B.

[0057] The output voltage Vout is a rectified voltage intended, for example, for a vehicle battery charger. The Vout voltage is taken from the terminals of a storage capacitor Cout, connected to the output terminals OH and OL of a second H-bridge 22 of the DAB double bridge. In Figure 1, the output impedance Zout between terminals OH and 16 is shown as a dashed line. This impedance represents, for example, the equivalent impedance (resistive and / or capacitive and / or inductive - RLC) of the circuits connected downstream of bridge 22.

[0058] The output bridge 22 has two parallel arms, or branches, C and D, each with two switches in series, respectively K5 and K7, K6 and K8, between the terminals OH and OL. The midpoint (interconnection node) between switches K5 and K7 of arm C is connected, for example and optionally by an RLC impedance, symbolized by its inductance LoH, to a first terminal of a secondary winding 24 of the transformer T, the other terminal of which is connected, for example and optionally by an RLC impedance, symbolized by its inductance LoL, to the midpoint (interconnection node) between switches K6 and K8 of arm D.

[0059] The transformer transformation ratio T is, for example, unity but can also be different from unity to add a variable in the ratio between the voltages Vout and Vin.

[0060] Each switch K1, K2, K3, K4, K5, K6, K7, K8 consists of a transistor. In one embodiment, the switches K1, K2, K3, K4, K5, K6, K7, K8 are MOSFET transistors. In another preferred embodiment, the switches K1, K2, K3, K4, K5, K6, K7, K8 are HEMT transistors, preferably of GaN technology.

[0061] The operation of a dual active bridge converter, as illustrated in Figure 1, is well known. Switches K1, K2, K3, K4, K5, K6, K7, and K8 receive on / off control signals (digital signals supplied, for example, by a microcontroller), respectively AH, BH, AL, BL, CH, DH, CL, and DL, which are adapted to the application and the power drawn by the load (not shown) connected downstream of the converter. As previously stated, the bridge control is configured to that the switching of the respective switches takes place in the vicinity of their zero voltage. These switching operations are also arranged in such a way as to avoid simultaneous conduction of the two switches of the same arm.

[0062] The pulse control of a converter of the type illustrated in Figure 1 is generally phase-shifted between the respective openings and closings of the upstream (input) and downstream (output) H-bridges so as to ensure energy transfer taking into account a power setpoint. The phase shifts introduced contribute to increasing common-mode noise.

[0063] Figure 2 represents, in a very schematic and block-like manner, one embodiment of a conversion system.

[0064] According to this embodiment, two DAB and DAB2 converters with dual active bridges of the type illustrated in Figure 1 are to be interleaved. Interleaved means that the respective H-bridges of the two DAB and DAB2 converters are connected in series or parallel, but that the two-converter conversion system has only two input terminals 12 and 14 and two output terminals 16 and 18.

[0065] According to the embodiment described in relation to Figure 2, a configurable conversion system is provided in which the serial or parallel connection at the input and output is obtained by sets of configuration switches. In practice, and as will be seen in relation to Figures 3 and 9 to 11, the parallel or series connection of the input bridges of the two converters and the parallel or series connection of the output bridges of the two converters is selected, preferably automatically by a microcontroller-type control circuit, according to the voltages and power levels. input and output. For example, in the case of an electric vehicle charging system, this allows, as will be detailed later, for the same charging station to automatically adapt to the voltage required by a vehicle connected to it.

[0066] For simplicity, the internal structure of each converter is not shown in Figure 2. Only the power input and output terminals connected, via series-parallel switch sets SIH, SIL, SOH, and SOL, respectively, to terminals 12, 14, 16, and 18, respectively, as well as the control terminals of the bridge switches, are shown. The control terminals A1H, AIL, BIH, B1L, C1H, CIL, DIH, and D1L correspond to terminals AH, AL, BH, BL, CH, CL, DH, and DL (Figure 1) of the first DABI converter. The control terminals A2H, A2L, B2H, B2L, C2H, C2L, D2H, and D2L correspond to terminals AH, AL, BH, BL, CH, CL, DH, and DL (Figure 1) of the second DAB2 converter.

[0067] For a parallel connection of the input bridges of the two DABI and DAB2 converters, their respective input terminals IH1 and IH2 (arbitrarily designated as high inputs) are connected to terminal 12 and their respective input terminals IL1 and IL2 (arbitrarily designated as low inputs) are connected to terminal 14. In Figure 2, this corresponds to the position illustrated in solid lines of the SIH and SIL switches.

[0068] For a series connection of the input bridges of the two converters, the high input terminal IH1 of the DABI converter is connected, preferably connected, to terminal 12. The low input terminal IL1 of the DABI converter is connected, preferably connected, to the high input terminal IH2 of the DAB2 converter. The low input terminal IL2 of the DAB2 converter is connected, preferably connected, to the terminal 14. In figure 2, this corresponds to the position illustrated in dotted lines of the SIH and SIL switches.

[0069] For a parallel connection of the output bridges of the two DABI and DAB2 converters, their respective output terminals OH1 and OH2 (arbitrarily designated as high outputs) are connected to terminal 16 and their respective output terminals OL1 and OL2 (arbitrarily designated as low outputs) are connected to terminal 18. In Figure 2, this corresponds to the position illustrated in solid lines of the SOH and SOL switches.

[0070] For a series connection of the output bridges of the two DABI and DAB2 converters, the high output terminal OH1 of the DABI converter is connected, preferably connected, to terminal 16. The low output terminal OL1 of the DABI converter is connected, preferably connected, to the high output terminal OH2 of the DAB2 converter. The low output terminal OL2 of the DAB2 converter is connected, preferably connected, to terminal 18. In Figure 2, this corresponds to the position shown by the dashed lines of the switches SOH and SOL.

[0071] The control of the DABI and DAB2 converter switches is provided by a circuit 26, for example a microcontroller, which adjusts the respective closing and opening times of the switches (the duty cycle of the control signals). Circuit 26 provides control signals CTA, CTA', CTB, CTB', CTC, CTC, CTD, and CTD', intended for the switches of the DABI and DB2 converters. Circuit 2 is powered by a low voltage (on the order of a few volts) Vcc. Preferably, circuit 26 also provides the control signals to the switch sets SIH, SIL, SOH, and SOL.

[0072] One difference between the control signals of the switches is that the SIH, SIL, SOH, and SOL switches are statically controlled, meaning they remain in a same position for given voltages and powers, while the bridge switches are controlled dynamically (at a frequency greater than 100 kHz).

[0073] Depending on the application, the duty cycle of the control signals CTA, CTA', CTB, CTB', CTC, CTC, CTD, and CTD' is preferably fixed, but can be variable. In the case of a variable duty cycle, the duty cycles remain identical in pairs (e.g., CTA, CTA') to maintain opposing control. Circuit 26 then receives, for example, REF information on a desired output voltage value Vout and on the input voltage value Vin, and information on the output voltage Vout, so that it can dynamically adapt the control of the bridge switches accordingly, if necessary.

[0074] In the embodiment illustrated in Figure 2, the transistors to which the control signals are applied are reversed from one converter to the other and arm by arm. Thus, the CTA, CTB, CTC and CTD signals are applied to the control terminals A1H, BIH, C1H, D1H of the transistors of the DABI converter and to the control terminals A2L, B2L, C2L, D2L of the DAB2 converter, while the CTA', CTB', CTC and CTD' signals are applied to the control terminals AIL, B1L, CIL, D1L of the transistors of the DABI converter and to the control terminals A2H, B2H, C2H, D2H of the DAB2 converter.

[0075] We can already see an advantage of the described conversion system, namely that it does not require modification of the control circuit compared to a circuit designed for a double active bridge converter of the type illustrated in figure 1. The described system is therefore easily transposable to existing conversion systems.

[0076] The prediction of common signals for DABI and DAB2 converters constitutes an implementation method preferred and simple. Alternatively, circuit 26 may be provided to generate eight signals for the DABI converter and eight signals for the DAB2 converter separately, provided that these signals respect the condition of inverting the signals between the lower transistors of one bridge with respect to the upper transistors of the other bridge.

[0077] Preferably, the control signals CTA, CTA', CTB, CTB', CTC, CTC, CTD and CTD' all have a duty cycle of around 50%.

[0078] In another embodiment, the DABI and DAB2 converters are controlled using pulse-width modulation according to the requirements of the downstream connected load and the input power. In yet another example, control is achieved using pulse-frequency modulation. The two examples above can, of course, be combined.

[0079] The parallel / series input and output configuration of the converters in the system shown in Figure 2 depends on the application and, in particular, on the component sizing (especially switches) and voltage levels.

[0080] One advantage of the described solution is that by providing parallel or series connection of the converters and by providing reverse control of one converter with respect to the other, the high frequency common mode currents (greater than 100 kHz) are reduced to the level of parasitic capacitances, linked to the switching of the bridge switches.

[0081] One advantage of the described solution, in which the values ​​of the inductive elements LiH, LiL, LoH and LoL connecting the H-bridges of each converter to the transformer of that converter are identical, is that this reduces low-frequency (below kHz) common-mode currents. particularly related to the alternations of the alternating voltage from which the voltage Vin is produced.

[0082] Figure 3 schematically represents an example of a system configuration of Figure 2 with parallel inputs and parallel outputs. For simplicity, the switch sets SIH, SIL, SOH, and SOL are not shown in Figure 3.

[0083] In the example of Figure 3, the conversion system is completed by a controllable full-wave rectifier bridge 3, of which two AC input terminals 31 and 33 are connected, via a common-mode filter 4, to two terminals 41 and 43 for the application of an AC voltage VAC, for example, the voltage of the electrical distribution network, and of which two rectified output terminals 35 and 37 are connected, preferably connected, to the input terminals 12 and 14 of a double converter of the type illustrated in Figure 2.

[0084] The rectifier bridge 3 can be any rectifier bridge suitable for the application. In the example shown, this bridge 3 has two branches, each containing two MOSFET transistors, 32 and 34, and 36 and 38 respectively, in series between terminals 35 and 37. The midpoint between transistors 32 and 34 is connected, preferably, to terminal 31. The midpoint between transistors 36 and 38 is connected, preferably, to terminal 33. The control of the rectifier bridge 3, compared to that of the dual converter, is at a significantly lower frequency, a function of the AC voltage frequency. The rectifier bridge can be controlled by pulse-width modulation depending on the power to be transmitted. The control signals applied to the gates of transistors 32, 34, 36, and 38 are, for example, provided by the microcontroller-type control circuit 26 (Figure 2).

[0085] On the dual converter side with dual active H-bridges, we find the architecture illustrated in Figure 2 with the DABI and DAB2 converters connected in parallel at the input and output. The switches are shown as transistors.

[0086] The respective transistors of the DABI and DAB2 converters in Figure 3 are designated by references corresponding to those used for the switches in Figure 1, adding "1" or "2" depending on whether it is the DABI converter or the DAB2 converter.

[0087] Thus, for the DABI converter, the transistors are respectively K11 (control terminal A1H) and K31 (control terminal AIL) for arm A, K21 (control terminal B1H) and K41 (control terminal B1L) for arm B, K51 (control terminal C1H) and K71 (control terminal CIL) for arm C, K61 (control terminal D1H) and K81 (control terminal D1L) for arm D. The primary winding 231 of the transformer T1 of the DABI converter is associated with the primary series inductances LiH1, LiL1 and the secondary winding 241 is associated with the secondary series inductances LoH1, LoL1.

[0088] For the DAB2 converter, the transistors are respectively K12 (control terminal A2H) and K32 (control terminal A2L) for arm A, K22 (control terminal B2H) and K42 (control terminal B2L) for arm B, K52 (control terminal C2H) and K72 (control terminal C2L) for arm C, K62 (control terminal D2H) and K82 (control terminal D2L) for arm D. The primary winding 232 of the transformer T2 of the DAB2 converter is associated with the primary series inductances LiH2, LiL2 and the secondary winding 242 of the transformer T2 is associated with the secondary series inductances LoH2, LoL2.

[0089] Since the two DAB1 and DAB2 converters are in parallel at input and output, they share the same input capacity Cin and the same output capacity Cout. With reference to Figure 2, assuming that the respective capacities of the DABI and DAB2 converters are contained in the blocks, this amounts to considering that the capacity Cin of Figure 3 corresponds to the parallel association of the input capacities of the DABI and DAB2 converters of Figure 2, and that the capacity Cout of Figure 3 corresponds to the parallel association of the output capacities of the DABI and DAB2 converters of Figure 2.

[0090] Compared to a converter of the type shown in Figure 1, an advantage of the parallel / parallel system shown in Figure 2 is that, for given power or voltage, the components (especially the transistors constituting the switches) can be sized for a lower power / voltage.

[0091] Figures 4, 5, 6, 7 and 8 illustrate, in the form of chronograms, the operation of a conversion system of the type illustrated in figure 3.

[0092] Figure 4 shows timing diagrams of an example of control signals CTA, CTA', CTB, CTB', CTC, CTC, CTD, CTD', applied to the gates of the transistors of the DABI and DAB2 converters.

[0093] The CTA signal is applied to terminals A1H and A2L and controls transistors K11 and K32. The CTA' signal is applied to terminals A1L and A2H and controls transistors K31 and K12. The CTB signal is applied to terminals B1H and B2L and controls transistors K21 and K42. The CTB' signal is applied to terminals B1L and B2H and controls transistors K41 and K22. The CTC signal is applied to terminals C1H and C2L and controls transistors K51 and K72. The CTC signal is applied to terminals C1L and C2H and controls transistors K71 and K51. The CTD signal is applied to terminals D1H and D2L and controls transistors K61 and K82. The DTA' signal is applied to terminals D1L and D2H and controls transistors K81 and K62.

[0094] The signals CTA, CTA', CTB, CTB', CTC, CTC', CTD, CTD' are digital signals which, when applied to the respective gates of the transistors constituting the switches, cause these transistors to conduct when the control signal is high and to block when the signal is low. Thus, the transistors are controlled in an on / off manner.

[0095] As illustrated by the timing diagrams in Figure 4, a slight time offset (tA, tB, tC, tD) is generally used between the respective rising edges of the control signals for the transistors in the same arm. This is to avoid the risk of simultaneous conduction of the transistors in the same arm. The offsets tA, tB, tC, and tD preferably, but not necessarily, all have the same value. Preferably, the duty cycles of the control signals in the same arm are slightly different (a few percent difference). In the example shown, the duty cycle of the signals CTA', CTB, CTC, and CTD is lower than that of the respective signals CTA, CTB', CTC, and CTD'.

[0096] Figure 4 also illustrates an example of a phase shift D, corresponding to the phase shift between arms C and D of each converter. This phase shift D is the intentional phase shift introduced to meet the power demand and maintain efficiency by keeping the control signal close to zero voltage.

[0097] All these phase shifts, duty cycle deviations, and time offsets generate common-mode noise at each converter, just as in a conventional converter. However, as illustrated in the following figures, the specific combination described of the two converters and their control signals within of the same conversion system generates a compensation of the common mode noise of one converter by the common mode noise of the other.

[0098] Figure 5 shows timing diagrams of control signals from one arm of the conversion system in Figure 3.

[0099] More specifically, Figure 5 shows the shapes of the A1H, AIL, A2H and A2L control signals of the K11, K21, K112, K22 transistors of the A arms of the DABI and DAB2 converters, highlighting the identity of the A1H and A2L signals, respectively AIL and A2H.

[0100] Although the corresponding shapes have not been shown, the same identity is found at the level of each arm, namely that the control signal of a switch of each arm of a converter is identical to the control signal of the other switch of the same arm (the switch having the opposite position in the arm) of the other converter.

[0101] Figure 6 shows timing diagrams of the corresponding respective waveforms of the respective voltages across transistors K21 and K22.

[0102] As shown in Figure 6, the drain-source voltages VdsK21 and VdsK22 across the low transistors of branches A of the DABI and DAB2 converters are in opposite phase.

[0103] Similar patterns are obtained for the transistors respectively: K41 and K42 of branches B; K61 and K62 of branches C; and K81 and K82 of branches D.

[0104] Figure 7 shows timing diagrams of the respective waveforms of the voltages V231 and V232 across the respective terminals of windings 231 and 232 of transformer T1 of the first DABI converter. This figure highlights the impact that phase shift can have on common-mode noise with a single converter. More specifically, this figure shows the voltage variations related to phase shifts between switching edges in the arms of the same bridge. These variations cause common-mode currents via parasitic grounding capacitances.

[0105] Figure 8 represents timing diagrams corresponding to the level of the second DAB2 converter, that is to say the respective shapes of the voltages V231 and V232 at the terminals of the windings 241 and 242 of the transformer T2 of the second DAB2 converter.

[0106] The combination of figures 7 and 8 shows the compensation achieved through the symmetry between the signals obtained.

[0107] Figure 9 shows an example of a system configuration of Figure 2 in which the input bridges of the DABI and DAB2 converters are connected in parallel and the output bridges are connected in series. For simplicity, the switch sets SIH, SIL, SOH, and SOL are not shown in Figure 9.

[0108] Compared to the conversion system shown in Figure 3, the lower output terminal OL1 of the DABI converter is connected, preferably, to the upper output terminal OH2 of the DAB2 converter. It follows that capacitors Coutl and Cout2 are in series between output terminals 16 and 18.

[0109] The rest of the conversion system is similar to that in Figure 3.

[0110] Compared to a parallel-to-parallel conversion system in Figure 3, the parallel-to-series system in Figure 9 provides, with the same component dimensions and the same input voltage Vin, an output voltage Vout of double value.

[0111] As a specific example of implementation, for an AC input voltage VAC of 230 volts, an output voltage Vout of the order of 800 volts can be obtained while having switches sized for voltages of 400 to 600 volts (the switches of the input bridges only see the order of 400 volts).

[0112] Figure 10 shows an example of a system configuration of Figure 2 in which the input bridges of the DABI and DAB2 converters are connected in series and the output bridges are connected in parallel. For simplicity, the switch sets SIH, SIL, SOH, and SOL are not shown in Figure 10.

[0113] Compared to the conversion system shown in Figure 3, the lower input terminal IL1 of the DABI converter is connected, preferably, to the upper input terminal OH2 of the DAB2 converter. It follows that capacitors Cinl and Cin2 are in series between input terminals 12 and 14.

[0114] The rest of the conversion system is similar to that in Figure 3.

[0115] Figure 11 shows an example of a system configuration of Figure 2 in which the input bridges of the DABI and DAB2 converters are connected in series and the output bridges are connected in parallel. For simplicity, the SIH, SIL, SOH, and SOL switch points are not shown in Figure 11.

[0116] Compared to the conversion system shown in Figure 9, the lower input terminal IL1 of the DABI converter is connected, preferably, to the upper input terminal OH2 of the DAB2 converter. It follows that the capacitors Cinl and Cin2 are also in series between input terminals 12 and 14.

[0117] The transistor control signals of the various bridges are not affected by the serial or parallel connection mode at the input or output. The same signal inversion is always expected from one converter to the other, as illustrated in Figure 2.

[0118] Thus, the method of connecting the converters depends, for a given dimensioning of the components, on the input and output voltage levels.

[0119] In practical implementation, it is preferable to position the input bridge of one converter as close as possible to the output bridge of the other. This reduces the impact of parasitic grounding capacitances and minimizes current paths by limiting magnetic fields due to current loops via parasitic grounding capacitances.

[0120] An example of the application of the described embodiments concerns electric vehicle battery charging systems. In such applications, the conversion system must be able to adapt the voltage from the electrical distribution network or the vehicle's alternator to the vehicle's battery or batteries, and vice versa.

[0121] One advantage of the described embodiments is that they allow us to benefit from the advantages of near-zero voltage control while minimizing the generated common-mode noise.

[0122] Another advantage of the described embodiments is that they allow for a reduction in the size of the common-mode filters used to filter electromagnetic interference.

[0123] Another advantage of the described embodiments is that they allow for an increase in the switching frequency of the switching of switching converters (for example at around 400-500 kHz) while preserving common mode noise compatible with electromagnetic interference standards.

[0124] Another advantage of the described embodiments is their compatibility with control signal generation designed for a typical active double-bridge converter. It is sufficient to apply the control signals to one converter and their inverse to the other.

[0125] The described embodiments are particularly well-suited to the use of GaN transistors as switches because they allow for an increased switching frequency, and therefore higher efficiency of the conversion system. However, they are not limited to this type of transistor and are also advantageous for converters based on MOSFET or SiC transistors by reducing common-mode noise for a given switching frequency.

[0126] A dual converter system with dual active bridges as described can be used not only in single-phase conversion applications but also in three-phase applications.

[0127] To create a three-phase conversion system, three pairs of double converters are required, such as the pair illustrated in Figure 2. The converters are connected, in pairs, in the same way as three converters of the type shown in Figure 1.

[0128] Various embodiments and variations have been described. Those skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will become apparent to them. In particular, galvanic isolation structures other than transformers Connections can be provided between the two H-bridges of the same converter, for example of a capacitive or piezoelectric nature.

[0129] Finally, the practical implementation of the described embodiments and variants is within the reach of a person skilled in the art, based on the functional indications given above, particularly with regard to the generation of control signals adapted to the described conversion system.

Claims

CLAIMS Switching power supply system comprising: two active double bridge converters (DABI, DAB 2); a first set of switches (SIH, SIL) connecting two terminals (12, 14) for applying a first voltage (Vin) to the two input terminals (IH1, IL1; IH2, IL2) of each converter or respectively to a single input terminal (IH1, IL2) of each converter; a second set of switches (SOH, SOL) connecting two terminals (16, 18) for supplying a second voltage (Vout) to the two output terminals (0H1, 0L1; 0H2, 0L2) of each converter or respectively to a single output terminal (0H1, 0L2) of each converter; and a control circuit for the switches of the first and second sets, the switches (K11, K21, K31, K41, K51, K61, K71, K81; K12, K22, K32, K42, K52, K62, K72, K82) of the converters (DABI; DAB2) being controlled in opposition from one converter to the other.A system according to claim 1, wherein the switches (SOH, SOL) of the second set are controlled according to the desired value for the second voltage (Vout). A system according to claim 1 or 2, wherein the switches of the first set are controlled according to the required output power. A system according to any one of claims 1 to 3, wherein: a first input terminal (IH1) of the first converter (DABI) is connected to a first application terminal (12) of a first voltage (Vin) and, by a. first switch (SIH) of the first set, to a first input terminal (IH2) of the second converter; a second input terminal (IL1) of the first converter (DABI) is connected, by a second switch (SIL) of the first set, to the second terminal (14) of application of the first voltage or to the first input terminal (IH2) of the second converter (DAB2); a first output terminal (0H1) of the first converter (DABI) is connected to a first terminal (16) of supply of a second voltage (Vout) and, by a first switch (SOH) of the second set, to a first output terminal (0H2) of the second converter (DAB2); and a second output terminal (0L1) of the first converter (DABI) is connected, by a second switch (SOL) of the second set, to a second terminal (18) of supply of the second voltage or to the first output terminal (0H2) of the second converter.System according to any one of claims 1 to 4, wherein each converter (DABI; DAB2) comprises: a first H-bridge comprising a first (A) and a second (B) parallel arms of two switches (K11, K21, K31, K41; K12, K22, K32, K42) in series between the two input terminals (IH1, IL1; IH2, IL2) of the converter; a second H-bridge comprising a third (C) and a fourth (D) parallel arms of two switches (K51, K61, K71, K81; K52, K62, K72, K82) in series between the two output terminals (0H1, 0L1; 0H2, 0L2) of the converter; a transformer (T1; T2) of which a first winding (231; 241) is connected to the respective interconnection nodes of the series switches of the first and second arms and of which a second winding. is connected to the respective interconnection nodes of the series switches of the third and fourth arms. System according to claim 5, wherein four inductive elements (LiH, LiL, LoH, LoL) are respectively interposed between each winding end and the interconnection node to which that end is connected. System according to claim 6, wherein said inductive elements all have the same value. System according to any one of claims 5 to 7, wherein each H-bridge comprises: a first switch (K11; K12) and a second switch (K21; K22) in series in the first arm (A); a third switch (K31; K32) and a fourth switch (K41; K42) in series in the second arm (B); a fifth switch (K51; K52) and a sixth switch (K61; K62) in series in the third arm (C); a seventh switch (K71; K72) and an eighth switch (K81; K82) in series in the fourth arm (D) A system according to claim 8, wherein: the first switch (K11, K12) of each converter is turned on, respectively blocked, at the same time as the second switch (K22; K21) of the other converter; the third switch (K31, K32) of each converter is turned on, respectively blocked, at the same time as the fourth switch (K42; K41) of the other converter; the fifth switch (K51, K52) of each converter is turned on, respectively blocked, at the same time as at the same time as the sixth switch (K62; K61) of the other converter; the seventh switch (K71, K72) of each converter is turned on, respectively blocked, at the same time as the eighth switch (K82; K81) of the other converter. System according to any one of claims 5 to 9, wherein the transformation ratio of the transformers (T1, T2) of the first and second converters (DABI, DAB2) is equal to 1. System according to any one of claims 1 to 10, wherein the switches (K11, K21, K31, K41, K51, K61, K71, K81; K12, K22, K32, K42, K52, K62, K72, K82) are GaN-type HEMT transistors. System according to any one of claims 1 to 11, wherein the switches (K11, K21, K31, K41, K51, K61, K71, K81; K12, K22, K32, K42, K52, K62, K72, K82) are controlled at a switching frequency of several hundred kHz, preferably greater than 400 kHz.A system according to any one of claims 1 to 11, comprising a single pair of converters (DABI, DAB2) and wherein the first voltage (Vin) is supplied by a rectification circuit (3) of a single-phase alternating voltage (Vac). A system according to any one of claims 1 to 11, comprising three pairs of converters (DABI, DAB2) and wherein the first voltage (Vin) of each converter is extracted from a rectification of a three-phase alternating power supply. A system according to any one of claims 1 to 11. 13, in which the second voltage (Vout) is intended to charging a battery, preferably a motor vehicle battery.

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