Method for controlling a power converter

Abstract

The invention relates to a method for controlling a power converter, the adjustment of which is provided by electronic power components used in switching at a switching frequency (fsw), the converter being controlled by at least one control variable (fsw), the control variable (g) being calculated at a control frequency (g), the switching frequency (fsw) being an integer multiple of the control frequency (fc), characterised in that the method comprises providing an estimate (ĝ) of the control variable at the switching frequency (fsw), outside the instants of calculation of the control variable (g).

Description

DESCRIPTIONTitle of the invention: Method for controlling a power converter

[0001] Technical field

[0002] The present invention relates to the field of power electronics, and in particular to a method for controlling a power converter.

[0003] Among the various AC / DC or DC / DC converter topologies, DAB (Dual Active Bridge) converters are currently attracting great interest, particularly in the field of electric vehicles. A DAB converter typically consists of two H-bridges that transfer power through a transformer.

[0004] DAB converters have high power density, which is advantageous for battery charging, and they can operate at high switching frequencies, which allows for smaller components.

[0005] In a switching power converter, comprising a plurality of controlled switches, the transition from the on state to the off state, and vice versa, of each of the switches, must be carried out according to a certain sequence, and a certain delay between each switching, in order to transfer the maximum power during the conversion, while ensuring switching of the converters in ZVS mode ("Zero Voltage Switching" or switching at zero voltage). tension).

[0006] Thus, switch control methods have been designed, allowing the desired performance level to be obtained for each converter topology.

[0007] Examples of methods for controlling a converter comprising two H-bridges and connected by a transformer have been described in [1], [2] and [3].

[0008] The computers used to control the switching of the switches must be able to calculate the switching commands in real time, based on the control variables measured at the converter level. These computers are generally embedded in the electric vehicle charger.

[0009] However, in the context of the development of three-phase power supplies for electric vehicles, which makes it possible to triple the power supplied, the integration of three calculators with constant charger volume is currently difficult to envisage.

[0010] Thus, it was considered to sub-sample the control of the switches. By performing a sub-sampling of the command, the calculator has a real-time calculation constraint which is alleviated, which provides a gain in volume of the calculator.

[0011] The principle of command subsampling in a DAB converter is described in [4].

[0012] Undersampling involves blocking the commands until the next control calculation time. Since the input voltage varies (for an AC voltage to be converted), as does the power setpoint, the converter will deviate from the nominal operation between two command calculation times, especially since the decimation factor is large.

[0013] There is therefore a need to mitigate the effects of control subsampling, at reduced (or even negligible) computational cost compared to sampling nominal.

[0014] Summary of the invention

[0015] An object of the invention is therefore a method for controlling a power converter whose regulation is ensured by electronic power components used in switching at a switching frequency, the converter being controlled by at least one control variable, the control variable being calculated at a control frequency, the switching frequency being an integer multiple of the control frequency, characterized in that the method comprises a provision of an estimate of the control variable at the switching frequency, outside the instants of calculation of the control variable commande.

[0016] Advantageously, the estimation of the control variable is carried out with a first-order prediction model.

[0017] Advantageously, the power converter comprising two H-bridges connected by a transformer, the estimation of the control variable is defined by the relations: sinon ^�^ [ ^^] et ^�^ [ ^^ − 1 ] corresponding respectively to an estimate of the control variable at time ^^ ^^ sw and at the moment ( ^^ − 1) ^^ sw , where ^^ sw is the inverse of the switching frequency (f sw ) ^^ [ ^^ ] corresponding to a calculated value of the control variable (^^) at time ^^ ^^ sw ^^ corresponding to the ratio between the switching frequency ( ^^ sw ) and the control frequency ( ^^ c ), ^^1[ ^^] and ^^1[ ^^ − 1] corresponding respectively to the values of the voltage at the terminals of the transformer input at the instant ^^ ^^ sw and at the moment ( ^^ − 1) ^^ sw , ^�^ ^^ [ ^^ ] corresponding to a parameter calculated based on the last two calculated values ^^ [ ^^ ] et ^^ [ ^^ − ^^ ] , ^^ [ ^^ − ^^] corresponding to a calculated value of the control variable ( ^^) at time ( ^^− ^^) ^^ sw , and the two values of the voltage across the transformer input measured at the same times.

[0018] Advantageously, the parameter ^�^ ^^[ ^^] is determined by the following relation:^^[ ^^] − ^^[ ^^ − ^^]

[0019] Advantageously, the power converter comprising two H-bridges connected by a transformer, the estimation (^�^) of the control variable is defined by the relations: sinon ^^ ^^ [ ^^ ] corresponding to an analytical expression of the control variable ( ^^) ^^ corresponding to the ratio between the switching frequency ( ^^ sw ) and the control frequency ( ^^ c ) ; ^�^[ ^^] and ^�^[ ^^ − 1] corresponding respectively to an estimate of the control variable at time ^^ ^^ sw and at the moment ( ^^ − 1) ^^sw , where ^^ sw is the inverse of the switching frequency (f sw ) ; ^^ ^^_ ^^ [ ^^] corresponding to an adaptive parameter evaluated by an analytical expression; ^^1 [ ^^ ] et ^^1 [ ^^ − 1 ] corresponding respectively to the values of the voltage at the terminals of the transformer input at time ^^ ^^sw and at time ( ^^ − 1) ^^sw.

[0020] Advantageously, the control variable includes a phase shift variable between the bridges.

[0021] Advantageously, the phase shift variable between the bridges comprises a phase shift between the falling edge of the voltage across the transformer input and the falling edge of the voltage across the transformer output.

[0022] Advantageously, the whole multiple is equal to 2 or 4.

[0023] The invention also relates to a DAB type power converter, capable of implementing the aforementioned method.

[0024] The invention also relates to a three-phase charger, comprising a aforementioned power converter.

[0025] Description of the figures

[0026] Other characteristics, details and advantages of the invention will emerge from reading the description given with reference to the attached drawings given by way of example.

[0027] Figure 1 illustrates a lossless FB-FB (for "FullBridge-Full Bridge") DAB converter topology.

[0028] Figure 2 illustrates a Type 1 modulation waveform in boost mode for AC / DC power transfer.

[0029] Figure 3 illustrates a Type 2 modulation waveform in boost mode for AC / DC power transfer.

[0030] Figure 4 illustrates the different stages of the method according to the invention.

[0031] Figure 5 illustrates control variable curves.

[0032] Figure 6 illustrates transferred power curves.

[0033] Figure 7 illustrates control variable and transferred power error curves.

[0034] The method according to the invention can be applied to any type of power converter whose regulation is ensured by electronic power components used in switching at a switching frequency. As an example, the method is described for a DAB FB-FB converter, illustrated in Figure 1.

[0035] The converter ^^ ^^ ^^ ^^ includes an H-bridge ^^1, receiving the input voltage ^^1. By H-bridge, we mean a parallel association of at least two branches (branches ^^ ^^1 and ^^ ^^2 for the H-bridge ^^1) between two nodes or terminals (nodes ^^ ^^1 and ^^ ^^2 for the H-bridge ^^1).

[0036] Each bridge branch is defined by an association of two switches electrically in series between the branch terminals. In H-bridge ^^1, branch ^^ ^^1 includes switches ^^1 and ^^2 in series. Branch ^^ ^^2 includes switches ^^3 and ^^4 in series.

[0037] Node ^^ ^^1 is located between switches ^^1 and ^^2 in series, and node ^^ ^^2 is located between switches ^^3 and ^^4 in series.

[0038] Similarly, in H-bridge ^^2, branch ^^ ^^3 includes switches ^^5 and ^^6 in series. Branch ^^ ^^4 includes switches ^^7 and ^^8 en série.

[0039] Node ^^ ^^3 is located between switches ^^5 and ^^6 in series, and node ^^ ^^4 is located between switches ^^7 and ^^8 in series.

[0040] The converter further comprises a capacitive element ^^1 connecting the terminals ^^1 and ^^2 of the H-bridge ^^1. The voltage ^^ ^^ ^^is applied between terminals ^^1 and ^^2 through an impedance ^^1. The capacitive element ^^1 and the impedance ^^1 form a filter to limit variations, at each switching, of the voltage ^^ ^^ ^^ and / or the current supplied to the converter.

[0041] Similarly, the converter includes a capacitive element ^^2 connecting the terminals ^^3 and ^^4 of the H-bridge ^^2. The voltage ^^ ^^ ^^ ^^ between terminals ^^3 and ^^4 is provided by the converter through an impedance ^^2. The capacitive element ^^2 and the impedance ^^2 form a filter to limit variations, at each switching, of the voltage ^^ ^^ ^^ ^^ and / or the current supplied by the converter.

[0042] The first H-bridge ^^1 and the second H-bridge ^^2 are connected by a transformer ^^ ^^. The transformer ^^ ^^ includes a winding ^^ ^^1 connected to nodes ^^ ^^1 and ^^ ^^2, and a winding ^^ ^^3 connected to nodes ^^ ^^3 and ^^ ^^4.

[0043] The transformer ^^ ^^ has a transformation ratio ^^ ( ^^ : 1 by convention). The transformation ratio corresponds to a ratio between a number of turns of the second winding and a number of turns of the first winding.

[0044] The converter is considered to operate in boost mode, i.e. V1 < nV2 (m = V1⁄ nV2 < 1). In buck mode (m > 1), the same results can be used by making the following variable change: V1 ↔ nV2, V2 ↔ V1⁄ n .

[0045] The transformer ^^ ^^ includes a leakage inductance ^^, which connects one terminal of the winding ^^ ^^1 to the node ^^ ^^1. The inductance ^^ is crossed by a current i L ,and the voltage across the inductance ^^ is called ^^ ^^.

[0046] Thus, in each bridge, the switching of the branches forms a switching sequence. The switching sequences of the two branches are repeated at the switching frequency ^^ sw. At each repetition of the switching sequences, the leakage inductance has the role of storing / removing energy, in order to circulate this energy from one bridge to the other of the converter.

[0047] The leakage inductance ^^ has a variable voltage across its terminals equivalent to a voltage ^^ ^^ across the leakage inductance shown.

[0048] The switching sequences of the two branches are repeated at the switching frequency. At each repetition of the switching sequences, the leakage inductance ^^ has the role of storing / removing energy, so as to circulate the energy from one bridge to the other of the converter.

[0049] The converter further comprises a control circuit (not visible in the figure), which receives values representative of the respective voltages V1 and V2.

[0050]

[0100] The control circuit (or calculator) provides control signals for switches K1, K2, K3, K4, K5, K6, K7, and K8, as a function of modeled values of power transferred from the first bridge ^^1 to the second bridge ^^2, and from the values of voltages V1 and V2.

[0051] The skilled person may refer to one of the documents [1], [2] or [3], which describe in more detail the topology and control of a DAB FB-FB converter.

[0052] As illustrated in Figures 2 and 3, the voltage ^^ ^^ ^^1 on the primary side of the transformer ^^ ^^ consists of positive and negative pulses of amplitude ^^1. Similarly, the voltage ^^. ^^ ^^ ^^2 on the secondary side of transformer TR consists of positive and negative pulses of amplitude v2.

[0053] In the modulation example of Figure 2 (so-called type 1 modulation in boost mode for an AC / DC conversion), the transferable power is given by the relation:

[0055] g corresponds to the delay between the falling edge (instant t2) of the voltage ^^ ^^ ^^1 on the primary side and the falling edge (instant t3= T sw / 2) of the tension ^^. ^^ ^^ ^^2 on the secondary side.

[0056] w corresponds to the delay between the rising edge (time t1) and the falling edge (time t2) of the voltage ^^ ^^ ^^1 on the primary side.

[0057] By imposing the constraint iL(t1) = iL(t3) (which amounts to imposing ZVS conditions of zero voltage switching identical to these switchings), we obtain:

[0059] with m = V1 nV2

[0060] Thus, the converter control includes the determination of the control variable g, so that the transferable power p can be calculated.

[0061] Which gives:

[0063] When fsw is fixed, g is given by:

[0065] with

[0066] a = 2 − 2m2 > 0

[0067] b = −1 + m − 2m 2

[0069] In the modulation example of Figure 3 (type 2 modulation in boost mode for an AC / DC conversion), the transferable power is given by the relationship:

[0071] g corresponds to the delay between the falling edge (instant t2) of the voltage ^^ ^^ ^^1 on the primary side and the falling edge (instant t3= T sw / 2) of the tension ^^. ^^ ^^ ^^2 on the secondary side.

[0072] w corresponds to the delay between the rising edge (time t1) and the falling edge (time t2) of the voltage ^^ ^^ ^^1 on the primary side.

[0073] By imposing the constraint iL(t2) = iL(t0) (which amounts to imposing ZVS conditions of zero voltage switching identical to these switchings), we obtain:

[0084] The method according to the invention is not limited to the aforementioned modulation schemes, which are described only by way of example.

[0085] The developments will be illustrated for a triangular type modulation (see current iL at the bottom of figure 3) with a switching frequency f sw constant. The method is applicable for other types of modulations, such as phase-shift and trapezoidal modulations (see Figure 2), or with a variable switching frequency fsw.

[0086] It is essential, within the framework of the invention, that the converter is controlled by at least one control variable, which can be, for example, the delay ^^ between the falling edge of the voltage ^^ ^^ ^^1 on the primary side and the falling edge of the voltage ^^. ^^ ^^ ^^2 on the secondary side. Any other control variable can be used, provided that it corresponds to a delay between the voltage ^^ ^^ ^^1 on the primary side and the voltage ^^. ^^ ^^ ^^2 on the secondary side.

[0087] The method according to the invention is based on a sub-sampling of the control of the switches. Let ^^ cthe control calculation frequency, i.e. the frequency of calculation of the converter control variables, where ^^ c = ^^ sw ⁄ ^^ with ^^ the decimation factor, a strictly positive integer, e.g. ^^ = 2, 4, 8, etc.

[0088] Failure to calculate the control variable at the switching frequency f sw allows the real-time calculation constraint to be reduced, thus allowing the use of a smaller control circuit.

[0089] The larger the multiple ^^, the greater the effect of control subsampling. In Figures 5 and 6 described below, ^^ = 8, in order to obtain illustrative graphs. In practice, a division of the switching frequency by 2 or 4 would be more desirable, so as not to excessively degrade the stability margins of the closed-loop system.

[0090] Instead of blocking the commands until the next calculation instant, the method according to the invention comprises providing an estimate ^�^ of the control variable at the switching frequency f sw , outside the times of calculation of the control variable ^^: the missing values of the control at the switching frequency f sw between two times of order calculation are estimated.

[0091] For the modulation considered, the relationship that links the interval g between two falling edges to the voltage V1 between terminals B1 and B2 is a non-linear algebraic relationship. The voltage V1 is assumed to be known, and can be measured or estimated, for example with a phase-locked loop (PLL) for an alternating voltage ^^ ^^ ^^.

[0092] It is assumed that the other quantities involved in the calculation of g are constant or slowly variable (for example the voltage V2 between terminals B3 and B4, so that the first-order Taylor development is written, for the function g(V 1 ) :

[0094] where ΔV1 is a small variation around the voltage V1 for a given operating point.

[0095] The control variable differential Δ ^^ is defined by the following relation:

[0097] The estimation ^�^ of the control variable is carried out with a first-order prediction model, which gives very satisfactory results and simple calculations. The developments remain valid for higher orders and increased precision, at the cost of a greater computational load.

[0098] The method according to the invention proposes to estimate α and to calculate g at the control frequency f c , and estimate g at frequency f sw(outside the instants of calculation of g to fc).

[0099] The process is described in more detail in the flowchart illustrated by figure 4.

[0100] In the following, we will note ^^[ ^^] ≜ ^^[ ^^ ^^sw] ( ^^ ∈ ℕ) for a sampled variable ^^ dependent on time.

[0101] The control variable ^^ is calculated every ^^ periods ^^sw: ^^ = ^^ ^^, ^^ ∈ ℕ.

[0102] Thus, a counter of the calculator increments ^^ at the period Tc = ^^ ^^sw

[0103] At the first step S1, we set:

[0104] ^^ = 1, ^^ = ^^ ^^, ^^ ∈ ℕ

[0105] ^�^[0 to ^^ − 1] = ^^[0]

[0106] The test T1 consists of determining if ^^ = ^^ ^^.

[0107] If the result of the test T1 is negative, step S5 is implemented:

[0108] The estimated value ^�^ ^^[ ^^] corresponds to the value estimated at the last increment of ^^.

[0109] ^�^ ^^[ ^^] = ^�^ ^^[ ^^ − 1] (i.e. ^�^ ^^[ ^^] = ^�^ ^^[ ^^ ^^] )

[0110] Furthermore, if the result of test T1 is negative, the estimate ^�^[ ^^] of the control variable is calculated as follows:

[0111] ^�^[ ^^] = ^�^[ ^^ − 1] + ^�^ ^^[ ^^]. ( ^^1[ ^^] − ^^1[ ^^ − 1])

[0112] V1[i] and V1[i − 1] correspond respectively to the value of the voltage across the transformer input at time iTsw and at time (i − 1)Tsw.

[0113] The calculator then increments ^^ to the following value: ^^ = ^^ + 1 (step S6).

[0114] If the result of test T1 is positive, step S2 is implemented. It consists of calculating the control variable ^^[ ^^], in a manner known to those skilled in the art. For example, with the relationship defined previously for type 1 modulations. et 2 :

[0116] Thus, the calculation of g is performed at a control frequency ^^c = fsw / ^^, which lightens the computational load by a factor ^^.

[0117] Step S2 also includes updating the estimate ^�^[ ^^]:

[0118] ^�^[ ^^] = ^^[ ^^]

[0119] The estimate ^�^[ ^^ − 1] is used for step S5,.

[0120] The next step S3 consists of determining the parameter ^�^ ^^[ ^^] based on the last two calculated values ^^ [ ^^ ] et ^^ [ ^^ − ^^ ] , ^^ [ ^^ − ^^ ] corresponding to a calculated value of the control variable ^^ at time ( ^^− ^^) ^^ sw, and the two values of the voltage across the transformer input measured at the same times. ^^ [ ^^ − ^^ ] corresponds to the calculation of ^^ to the previous increment of ^^.

[0122] The next step S4 consists of an increment, by the calculator, of the value of ^^. The calculator then increments ^^ to the following value: ^^ = ^^ + 1 (step S6).

[0123] After the execution of step S6, the method returns to test T1. It is understood that each iteration of test T1 is executed at the switching frequency fsw.

[0124] Figures 5, 6 and 7 illustrate the benefits provided by the method according to the invention.

[0125] For this example, the operating point considered for the converter is 230 ^^ ^^ ^^ ^^, ^^2 = 400 ^^, ^^1 = 16 ^^ ^^ ^^ ^^, ^^ = 1, ^^ = 4.5 ^^ ^^ with an open-loop lossless model and switches considered perfect. The converter is driven at f sw= 100 kHz in modulation 2 (triangular type) in booster mode ("boost" mode).

[0126] The left part of Figure 5 represents the control variable ^^ which represents the phase shift between the falling edge of the voltage at the terminals of the transformer input and the falling edge of the voltage at the terminals of the transformer output, over a period of 10 ms. The left part of Figure 5 also represents the estimated control variable ^�^ using the method according to the invention, as well as the control variable ^^ℎ ^^ ^^ ^^ obtained by blocking the control between two calculation instants, without estimation.

[0127] The right part of Figure 5 represents an enlargement of the left part, over the interval [4 - 4.3 ms].The estimated control variable ^�^ is almost confused with the calculated value of the control variable ^^ (the deviations are very small), while the control variable ^^ℎ ^^ ^^ ^^ obtained by blocking the control between two calculation instants tends to deviate from the calculated value ^^ at each instant.

[0128] The same effect is visible in Figure 6, which represents the power transferred ^^ from the first bridge ^^1 to the second bridge ^^2. On the right part, which represents an enlargement of the left part, over the interval [4 - 4.3 ms], the estimated power ^^̂ is confused with the calculated value of the power ^^ (see above for the calculation of the power), while the power ^^ℎ ^^ ^^ ^^ obtained in. blocking the command between two calculation times tends to deviate from the calculated value ^^ at each time.

[0129] Figure 7 illustrates the errors made on the control variable ^^ (graphs on the left of Figure 7, ^^ ^^ ^^ ^^ ^^ ^^_ℎ ^^ ^^ ^^ corresponds to the error between the theoretical control variable ^^ and the sub-sampled control variable, according to the state of the art; ^^ ^^ ^^ ^^ ^^ ^^_ ^^ ^^ ^^ corresponds to the error between the theoretical control variable ^^ and the control variable with the method according to the invention) and on the transferred power ^^ (graphs on the right of Figure 7 ^^ ^^ ^^ ^^ ^^ ^^_ℎ ^^ ^^ ^^ corresponds to the error between the theoretical transferred power ^^ and the sub-sampled transferred power ^^, according to the state of the art; ^^ ^^ ^^ ^^ ^^ ^^_ ^^ ^^ ^^ corresponds to the error between the theoretical transferred power ^^ and the transferred power with the method according to the invention), in units and percentages.

[0130] A change of scale, on the four graphs at the bottom, allows for a better evaluation of the estimation errors.

[0131] It appears that the maximum error on the control variable ^^ is 0.07% with the method according to the invention, whereas it is 5.2% with the blocking between two calculation times, according to the state of the art. It can be noted that the prediction model being linear, the error increases with the curvature of ^^ = ^^( ^^1).

[0132] It also appears that the maximum error on the transferred power ^^ is 0.14% with the method according to the invention, whereas it is 46% with the blocking between two calculation times, according to the state of the art. In Figure 7, top right, the power is zero at the ends of the interval [0, 10] ms. Thus, the calculation of the percentage error is restricted to powers greater than 10 W, i.e. in the interval [0.12 – 9.88] ms.

[0133] Thus, the method according to the invention makes it possible to apply a sub-sampling of the calculation of the control for the switches of each of the bridges of the converter, while considerably reducing the errors generated by the sub-sampling. The method thus makes it possible to propose a switching of the switches at high frequency, with smaller computer components, or in a dual manner, for a fixed calculation load, to increase the switching frequency.

[0134] According to an alternative embodiment, when an analytical expression of the control variable g is available, the parameter α can be evaluated and calculated, instead of being estimated, as is the case in the previously cited embodiment. This is therefore an advantage because the prediction model is more accurate.

[0135] The estimate g� of the control variable is defined by the relations: sinon

[0137] ^^ ^^ [ ^^] corresponds to an analytical expression of the control variable g

[0138] ν corresponds to the ratio between the switching frequency fsw and the control frequency fc.

[0139] αa_ ^^[i] corresponds to an adaptive parameter evaluated by an analytical expression.

[0140] V1[i] and V1[i − 1] correspond respectively to the values of the voltage across the transformer input at time iTsw and at time (i − 1)Tsw.

[0141] In 2 boost modulation, the analytical expressions of ^^ ^^ and αa are given below:

[0146] The analytical expressions could be determined for other modulation schemes.

[0147] These calculations can be complex, inducing a non-negligible computational load. Nevertheless, the determinations of the analytical expressions can be simplified by using lookup tables, in which the values of the analytical expressions of g and α would be stored.

[0148] The invention also relates to a power conversion system, comprising a converter and a control system which receives as input the set powers / voltages via measuring means, and which transmits to the converter switching control signals of the switches via calculation means. The electronic power components are used in switching at a switching frequency (f sw ). The control system calculates a control variable (^^) which is calculated at a control frequency (^^c), the switching frequency (fsw) being an integer multiple of the control frequency (f c ). The control system is configured to provide an estimate (^�^) of the control variable at the switching frequency (f sw ), outside the times of calculation of the control variable ( ^^). The control system is also capable of implementing one or other of the aforementioned embodiments.

[0149] Références citées :

[0150] [1] EP 3910774 A1

[0151] [2] EP 3910775 A1

[0152] [3] EP 3910776 A1

[0153] [4] A. A. P. Machado et I. A. Pires, « Undersampling Control for a DC–DCBoost and Forward Dual Active Bridge for a Single-Phase Grid-Connected PV Converter », J. Control Autom. Electr. Syst., vol.29, n o 5, p.650‑659, oct.2018, doi:10.1007 / s40313-018-0404-9.

Claims

CLAIMS 1. Method for controlling a power converter comprising two H-bridges connected by a transformer and whose regulation is ensured by electronic power components used in switching at a switching frequency (f sw ), the converter being controlled by at least one control variable ( ^^) in which the control variable ( ^^) comprises a phase shift variable between the bridges, the control variable ( ^^) being calculated at a control frequency ( ^^ c ), the switching frequency (f sw ) being an integer multiple of the control frequency (f c ), characterized in that the method comprises providing an estimate (^�^) of the control variable at the switching frequency (f sw), outside the times of calculation of the control variable ( ^^).

2. Method according to claim 1, in which the estimation ( ^�^) of the control variable is carried out with a first-order prediction model.

3. Method according to one of the preceding claims, in which the estimation ( ^�^) of the control variable is defined by the relations: sinon ^�^ [ ^^ ] et ^�^ [ ^^ − 1 ] corresponding respectively to an estimate of the control variable at time ^^ ^^ sw and at the moment ( ^^ − 1) ^^ sw , where ^^ sw is the inverse of the switching frequency (f sw ) ^^ [ ^^ ] corresponding to a calculated value of the control variable ( ^^) at time ^^ ^^ sw ^^ corresponding to the ratio between the switching frequency ( ^^ sw ) and the control frequency ( ^^ c), ^^1[ ^^] and ^^1[ ^^ − 1] corresponding respectively to the values ​​of the voltage at the terminals of the transformer input at the instant ^^ ^^ sw and at the moment ( ^^ − 1) ^^ sw , ^�^ ^^ [ ^^ ] corresponding to a parameter calculated based on the last two calculated values ​​^^ [ ^^ ] et ^^ [ ^^ − ^^ ] , ^^ [ ^^ − ^^ ] corresponding to a calculated value of the control variable ( ^^) at time ( ^^− ^^) ^^ sw , and the two values ​​of the voltage across the transformer input measured at the same times.

4. Method according to claim 3, in which the parameter ^�^ ^^ [ ^^] is determined by ^^[ ^^] − ^^[ ^^− ^^]the following relation: ^�^ ^^[ ^^] =� ^^ 1 [ ^^]− ^^1[ ^^− ^^] ^^ ^^ ^^ = ^^ ^^^�^ ^^[ ^^ − 1] otherwise5. The method of claim 1, wherein the estimation ( ^�^) of the control variable is defined by the relations: ^�^[ ^�^[ ^^ − 1] + ^ ^^_ ^^ ^^] ^ 1[ ^^] − ^1[ ^^ − 1]) otherwise, ^^ ^^[ ^^] corresponding to an analytical expression of the control variable ( ^^), ^^ corresponding to the ratio between the switching frequency ( ^^ sw ) and the control frequency ( ^^ c ) ; ^�^[ ^^] and ^�^ [ ^^ − 1 ] corresponding respectively to an estimate of the control variable at time ^^ ^^ sw and at the moment ( ^^ − 1) ^^ sw , where ^^ sw is the inverse of the switching frequency (f sw ) ; ^^ ^^_ ^^ [ ^^ ]corresponding to an adaptive parameter evaluated by an analytical expression; ^^1[ ^^] and ^^1[ ^^ − 1] corresponding respectively to the values ​​of the voltage at the terminals of the transformer input at time ^^ ^^ sw and at the instant( ^^ − 1) ^^sw.

6. Method according to claim 5, in which the phase shift variable between the bridges comprises a phase shift between the falling edge of the voltage across the terminals of the transformer input and the falling edge of the voltage across the terminals of the transformer output.

7. Method according to one of the preceding claims, in which the integer multiple is equal to 2 or 4.

8. Power converter of the DAB type, characterized in that it is capable of implementing the method according to one of the preceding claims.

9. Three-phase charger, characterized in that it comprises a power converter according to claim 8.

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