Active compensation device, converter, motor vehicle and associated process

Abstract

The active current overload compensation device for the input filter (15) of a power converter (12), the input filter being of at least second order and comprising a capacitor (21), the device being intended to be connected in parallel with the capacitor and comprising detection means (24) configured to detect a current overload in the input filter at or near the resonant frequency of the filter from the comparison of an estimate of the current flowing through the capacitor of the input filter to a first predetermined threshold.The device further includes an active compensation current source (25) configured to: - inject a compensation current (Icomp) into the input filter upon detection of a current overload in order to reduce the current overload, and - stop the injection of the compensation current when the current estimate is less than or equal to a second predetermined threshold, the second threshold being lower than the first threshold. Figure for the abstract: Fig 4.

Description

Title of the invention: Active compensation device, converter, motor vehicle and associated method

[0001] The present invention relates to reducing current overload in filter elements.

[0002] The present invention relates more particularly to an active current overload compensation device for an input filter of a power converter, a method implementing such a device, a power converter comprising such a device, and a motor vehicle comprising such a power converter.

[0003] Generally a hybrid or electric motor vehicle includes a power converter for charging the vehicle's battery from an electrical supply.

[0004] Generally, the power converter comprises a passive input filter of order greater than or equal to two comprising a capacitor.

[0005] The passive input filter makes it possible to filter voltage harmonics passing through the power supply and disturbing the converter's power supply, and to filter harmonic disturbances emitted by the power converter to its power supply network.

[0006] Since the passive input filter is of order greater than or equal to two, it has at least one resonant frequency.

[0007] The impedance of the filter is frequency dependent and is very low when the filter is excited at the resonant frequency.

[0008] When voltage harmonics disturb the continuous power supply of the converter at the resonant frequency, significant overload currents overloading the filter can appear.

[0009] The filter is sized to filter the disturbances emitted by the converter to the power supply so that the emission spectrum of the converter does not excite the resonant frequencies of the filter.

[0010] However, disturbances passing through the DC power supply, generally random, generate overload currents which can excite the filter at the resonant frequency leading to deterioration of the filter components.

[0011] Furthermore, since the spectrum of voltage disturbances in the power supply is not very deterministic, it is considered to be capable of covering the entire spectrum. The sizing of the filter components must take into account the worst case.

[0012] It is known to add a damping resistor in an order input filter two in series with the filter capacitance or to add capacitor-resistor associations in parallel with the branches of the filter of order higher than two to increase the input impedance of the filter in order to dampen the resonance peaks on the one hand, and to limit the overload currents on the other hand.

[0013] [Fig.l] illustrates an example of a power converter 1 comprising a filter 2 second order input passive.

[0014] The filter 2 comprises two input terminals connected to a DC power supply 3 and two output terminals connected to a conversion stage 4 of the power converter.

[0015] The filter 2 further comprises an inductor 5 connecting a first input terminal to a first output terminal, and a branch comprising a capacitor 6 connected in series with a damping resistor 7.

[0016] The branch extends between the two output terminals.

[0017] However, the addition of the damping resistor 7 in the filter 2 increases the size of the filter 2.

[0018] In addition, the resistor 7 dissipates heat which needs to be evacuated by a cooling device integrated in the filter 2, further increasing the size of the filter 2.

[0019] Furthermore, the damping resistor 7 degrades the operation of the filter 2.

[0020] Increasing the input impedance of the filter degrades the filtering performance of filter 2.

[0021] [Fig.2] illustrates a gain Bode diagram representing an example of a curve Cl relating the gain to the frequency of filter 2 without the addition of damping resistor 7, a curve C2 relating the gain to the frequency of filter 2 after the addition of damping resistor 7, and the resonance frequency Fres of filter 2.

[0022] It is noted that the filtering performance of the filter 2 comprising the damping resistor 7 is degraded compared to the filtering performance of the filter 2 not comprising the damping resistor 7 for frequencies higher than the resonance frequency Fres.

[0023] More high frequency voltage ripples are not filtered by the filter 2 including resistance 7.

[0024] One solution to meet the filtering requirements is to increase the filter size by lowering the resonant frequency to compensate for the filtering loss.

[0025] Document US 8,952,570 discloses the addition of a resistive damping device, and a contactor for connecting and disconnecting the resistive damping device according to the disturbances measured in an input filter.

[0026] However, a large volume is required to integrate into the filter all the components of a damped filter, the contactor and a cooling device. to cool the resistive damping device.

[0027] Reference may also be made to the document entitled “Circulating Reactive Power and Suppression Strategies in DC Power Electronics Networks” (published in 2021 in IEEE Applied Power Electronics Conference and Exposition (APEC) / DOI: 10.1109 / APEC42165.2021.9487129) which discloses the addition of resonant and / or anti-resonant circuits to an input filter to reduce overloads linked to external disturbances.

[0028] However, resonant and / or anti-resonant circuits are integrated into the input filter increasing the overall volume occupied by the filter.

[0029] The papers entitled “New Simple Active Damping of Resonance in Three-Phase PWM Converter with LCL Filter” and “Active Damping of Resonance Oscillations in LCL-Filters Based on Virtual Flux and Virtual Resistor” (published in 2005 in IEEE International Conference on Industrial Technology / DOI: 10.1109 / ICIT.2005.1600756) disclose means for estimating and suppressing the resonance of an input filter of a converter by driving the converter itself.

[0030] However, the means only act on the disturbances produced by the converter on the input filter and not on the random disturbances coming from the converter power supply.

[0031] It is therefore proposed to overcome all or part of the disadvantages of input filters for power converters according to the state of the art.

[0032] In view of the above, the subject of the invention is a method for active compensation of current overload in an input filter of a power converter, the input filter being of order at least equal to two, comprising the detection of a current overload in the input filter at the frequency or close to the resonant frequency of the filter from the comparison of an estimate of the current flowing in a capacitor of the input filter with a first predetermined threshold.

[0033] The method further comprises:

[0034] - the injection of a compensation current into the input filter by a source of active compensation current connected in parallel to the capacitor when detecting a current overload to reduce the current overload, and

[0035] - stopping the injection of the compensation current when the current estimate is less than or equal to a second predetermined threshold, the second threshold being less than the first threshold.

[0036] Preferably, detecting a current overload comprises:

[0037] - measurement of the voltage across the filter capacitor,

[0038] - filtering the measured voltage by a band-pass filter centered on the frequency of input filter resonance,

[0039] - the derivation of the filtered voltage with respect to time to obtain an estimate of the resonant current flowing through the resonant capacitance of the filter,

[0040] - the comparison of the current estimate with the first threshold, and

[0041] - determining a current overload if the current estimate is su greater than or equal to the first threshold.

[0042] Advantageously, the active compensation current source comprises an inductor, a first switching arm and a second switching arm each connected in parallel with the capacitance of the input filter and each formed by two switches connected in series, the midpoint of each switching arm being connected to a different end of the inductor, the injection of a compensation current comprises:

[0043] - controlling the switches to precharge the inductance so that the current compensation current flowing through the inductance is equal to a predetermined precharge current value, and

[0044] - when the compensation current is equal to the value of the precharge current, the control of the switches so that the estimate of the current flowing in the capacitor is less than or equal to the second threshold.

[0045] Preferably, a first switch of the first switching arm connected to a first end of the capacitor and to a first end of the inductor and a first switch of the second switching arm connected to the second end of the capacitor and to the second end of the inductor are controlled by a first control signal of frequency equal to the resonant frequency of the input filter, and a second switch of the first switching arm connected to the second end of the capacitor and to the first end of the inductor and a second switch of the second switching arm connected to the first end of the capacitor and to the second end of the inductor are controlled by a second control signal of frequency equal to the resonant frequency of the input filter,and controlling the switches includes adjusting the duty cycle of the first and second signals so that the current flowing in the capacitor is less than or equal to the second threshold.

[0046] The invention also relates to a device for active compensation of current overload for an input filter of a power converter, the input filter being of order at least equal to two and comprising a capacitor, the device being intended to be connected in parallel to the capacitor and comprising detection means configured to detect a current overload in the input filter at the frequency or close to the resonant frequency of the filter from the comparison of an estimate of the current flowing in the capacitor of the input filter with a first predetermined threshold.

[0047] The device further comprises an active compensation current source configured to:

[0048] - inject a compensation current into the input filter when detecting a current overload in order to reduce current overload, and

[0049] - stop the injection of the compensation current when the current estimate is less than or equal to a second predetermined threshold, the second threshold being less than the first threshold.

[0050] Preferably, the detection means comprise:

[0051] - measuring means configured to measure the voltage across the capacitor of the filter,

[0052] - a bandpass filter centered on the resonant frequency of the input filter configured to filter the measured voltage,

[0053] - time derivation means configured to obtain an estimate of the current at resonance through the capacitor by deriving the filtered voltage with respect to time, and

[0054] - comparison means configured to compare the estimate of the current to the first threshold, and determine a current overload in the input filter if the current estimate is greater than or equal to the first threshold.

[0055] Advantageously, the active compensation current source comprises an inductor, a first switching arm and a second switching arm each connected in parallel with the capacitance of the input filter and each formed by two switches connected in series, the midpoint of each switching arm being connected to a different end of the inductor, and further comprises control means configured to:

[0056] - control the switches in order to precharge the inductance so that the current compensation current flowing through the inductance is equal to a predetermined precharge current value,

[0057] - when the compensation current is equal to the value of the precharge current, control the switches so that the estimate of the current flowing in the capacitor is less than or equal to the second threshold, and

[0058] - stop the injection of the compensation current when the current estimate is less than or equal to a second predetermined threshold, the second threshold being less than the first threshold.

[0059] Preferably, a first switch of the first switching arm is connected to a first end of the capacitor and to a first end of the inductor, a first switch of the second switching arm is connected to the second end of the capacitor and to the second end of the inductor, a second switch of the first switching arm is connected to the second end of the capacitance and at the first end of the inductance, and a second switch of the second switching arm is connected to the first end of the capacitance and to the second end of the inductance, the control means being further configured to:

[0060] - deliver a first control signal of frequency equal to the frequency of resonance of the input filter on control inputs of the first switches,

[0061] - deliver a second control signal of frequency equal to the frequency of resonance of the input filter on control inputs of the second switches, and

[0062] - adjusting the duty cycle of the first and second signals so that the current circulating in the capacity is less than or equal to the second threshold.

[0063] The invention also relates to a power converter comprising an input filter intended to be connected to an electrical power supply and comprising a capacitor, and an active current overload compensation device as defined previously and connected in parallel to the capacitor.

[0064] The invention also relates to a motor vehicle comprising a power converter as defined above.

[0065] Other aims, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example, and made with reference to the appended drawings in which:

[0066] [Fig. 1], which has already been mentioned, schematically illustrates an example of a passive input filter according to the state of the art;

[0067] [Fig.2], which has already been mentioned, schematically illustrates a Bode gain diagram of the damped and undamped passive input filter according to the state of the art,

[0068] [Fig.3] schematically illustrates a motor vehicle,

[0069] [Fig.4] schematically illustrates an example of the embodiment of an input filter,

[0070] [Fig.5] schematically illustrates an example of the embodiment of detection means,

[0071] [Fig.6] schematically illustrates an example of the embodiment of control means,

[0072] [Fig.7] schematically illustrates an example of an active compensation method,

[0073] [Fig.8] illustrates an example of the temporal evolution of the current through the filter during a disturbance without intervention of a compensation device, and

[0074] [Fig.9] illustrates an example of the temporal evolution of the current through the filter during a disturbance with the intervention of the compensation device.

[0075] [Fig. 3] illustrates an electric or hybrid motor vehicle 10 comprising a battery 11 and a power converter 12 connected to the battery 11.

[0076] The power converter 12 is further connected to an electrical power supply 13 which may be external or internal to the vehicle (for example a fuel cell).

[0077] The power supply 13 delivers, for example, a direct voltage.

[0078] The converter 12 comprises a conversion unit 14 made from semiconductors and an input filter 15.

[0079] The input filter 15 is of order two and has a resonant frequency.

[0080] Alternatively, the input filter 15 may be of a higher order.

[0081] The input filter 15 has two input terminals 16, 17 connected to the power supply electrical 13 and two output terminals 18, 19 connected to the conversion unit 14.

[0082] The conversion unit 14 charges the battery 11 from the electrical energy delivered by the power supply 13 via the filter 15.

[0083] [Fig.4] illustrates an example of filter 15.

[0084] The filter 15 comprises an inductor 20 connected between a first input terminal 16 of said filter and a first output terminal 18 of said filter, a capacitor 21 comprising a first end 22 connected between the inductor 20 and the first output terminal 18 and a second end 23 connected to the second input terminal 17 and to the second output terminal 19.

[0085] A current flows through the capacitor 21.

[0086] The filter 15 further comprises an active current overload compensation device connected in parallel to the capacitor 21.

[0087] The compensation device comprises detection means 24 and an active compensation current source 25.

[0088] The detection means 24 detect a current overload in the input filter 15 at the resonance frequency from the comparison of an estimate (visible in [Fig.5]) of the current flowing in the capacitor 21 at the resonance of the filter to a first predetermined threshold SI (visible in [Fig.5]).

[0089] The estimate of the current Ic is determined by the detection means 24.

[0090] Furthermore, the detection means 24 generate a first signal S241 indicative of the estimate of the current Ic and a second signal S242 for starting or stopping the compensation device indicative of the detection of a current overload in the input filter 15 at the resonant frequency.

[0091] The current source 25 comprises a first connection terminal 26 connected to the first end 22 of the capacitor 21 and a second connection terminal 27 connected to the second end 23 of the capacitor 21.

[0092] The current source 25 injects a compensation current Icomp into the input filter 15 upon detection of a current overload in order to reduce the current overload, and stops the injection of the compensation current Icomp when the estimate lest of the current le is less than or equal to a second predetermined threshold S2 (visible in [Fig.5]).

[0093] The second threshold S2 is lower than the first threshold SL

[0094] The current source 25 comprises a second inductance 28, a first arm 29 switching arm, and a second switching arm 30.

[0095] Each switching arm 29, 30 comprises two identical switches 31, 32, 33, 34 connected in series.

[0096] Each switch 31, 32, 33, 34 comprises a power transistor 35, a diode 36, a first end 37 and a second end 38.

[0097] Transistor 35 is for example a field effect transistor.

[0098] The cathode of diode 36 is connected to the drain of transistor 35 and to the first end 37, and the anode of diode 36 is connected to the source of transistor 35 and to the second end 38.

[0099] The first end 37 of a first switch 31 of the first arm 29 is connected to the first connection terminal 26, and the second end of the first switch 31 is connected to the first end 37 of the second switch 32 of the first arm 29 and to a first end 39 of the second inductance 28.

[0100] The second end 38 of the second switch 32 is connected to the second connection terminal 27.

[0101] The first end 37 of a second switch 34 of the second arm 30 is connected to the first connection terminal 26, and the second end of the second switch 34 is connected to the first end 37 of the first switch 33 of the second arm 30 and to a second end 40 of the second inductance 28.

[0102] The second end 38 of the first switch 33 is connected to the second connection terminal 27.

[0103] The compensation device further comprises control means 41 connected to the gate of the transistor 35 of the switches 31, 32, 33, 34 and to the detection means 24 so as to receive the first and second signals S241, S242 delivered by the detection means 24.

[0104] The control means 41 control the switches to precharge the second inductance 28 upon detection of a current overload by the detection means 24 so that the value of the compensation current Icomp equal to the value of the current IL passing through the inductance is equal to a predetermined precharge current value.

[0105] The second inductance 28 delivers the compensation current Icomp.

[0106] A current sensor 100 measures the value of the current IL passing through the inductance and delivers the measured value to the control means.

[0107] When the compensation current Icomp is equal to the value of the precharge current, the control means 41 control the switches so that the estimate lest of the current le flowing in the capacitor is less than or equal to the first threshold S1, and stop the injection of the compensation current Icomp when the estimate lest of the current le is less than or equal to the second threshold S2.

[0108] The detection means 24 and the control means 41 are for example each produced from a processing unit.

[0109] Alternatively, the detection means 24 and the control means 41 are integrated into a processing unit.

[0110] The filter 15 may further comprise a temperature sensor 42 and a controller 43 connected to the temperature sensor 42 and to the control means 4L.

[0111] The sensor 42 measures the temperature of the capacity 21 and delivers the measured value to the controller 43.

[0112] From the measured temperature, the controller 43 determines and transmits to the control means 41 a reference current Icons (visible in [Fig.6]).

[0113] The controller 43 comprises for example a table linking the measured temperature values ​​to the setpoint current values ​​Icons.

[0114] Alternatively, the setpoint current Icons is a predetermined fixed value.

[0115] [Fig.5] illustrates an example of embodiment of the detection means 24.

[0116] They comprise a comparator 44, a bandpass filter 45, time derivation means comprising for example a derivator 46, a peak detection circuit 47 and comparison means comprising a hysteresis comparator 48.

[0117] The hysteresis comparator 48 is adjusted according to the first and second thresholds S1, S2.

[0118] Comparator 44 determines voltage V21 across capacitor 21 and delivers the value of voltage V21 at bandpass filter 45.

[0119] The bandpass filter 45 centered on the resonance frequency filters the voltage V21 so as to keep the frequencies of the voltage V21 around the frequency and delivers the filtered voltage Vf to the derivator 46.

[0120] The derivator 46 derives the filtered voltage Vf with respect to time to obtain the estimate lest of the current at resonance flowing in the capacitor le.

[0121] The ballast estimate of the current is transmitted to the peak detection circuit 47 which extracts the amplitude Aest from the ballast estimated current.

[0122] The hysteresis comparator 48 generates the signal S242 from the comparison of the amplitude Aest with the first and second thresholds SI, S2.

[0123] If the amplitude Aest is greater than or equal to the first threshold SI, a current overload in the filter 15 is detected by the detection means 24.

[0124] The second signal S242 generated by the hysteresis comparator 48 authorizes the injection of a compensation current Icomp by the current source 25.

[0125] When the amplitude Aest becomes less than or equal to the second threshold SI, the current overload is at an acceptable level.

[0126] The second signal S242 generated by the hysteresis comparator 48 stops the injection of a compensation current Icomp by the current source 25.

[0127] The first and second thresholds SI, S2 are fixed.

[0128] As a variant, the first and second thresholds SI, S2 are variable and determined for example by a microcontroller (not shown), delivering the thresholds SI and S2 as a function of parameters measured in the filter 15. By way of example, the thresholds SI and S2 may be a decreasing function of the temperature measurement provided by the sensor 42.

[0129] [Fig.6] illustrates an example of embodiment of the control means 41.

[0130] The control means 41 comprise a first comparator 50, a first corrector 51, a second comparator 52, a second corrector 53, and a control module 54 for the transistors 35.

[0131] The first comparator 50 comprises an addition input receiving the reference current Icons and a subtraction input receiving the estimate of the current at resonance.

[0132] An output of the first comparator 50 is connected to an input of the first corrector 51 comprising an output connected to an addition input of the second comparator 52.

[0133] The output of the first corrector 51 delivers a current ILref of the reference current IL flowing in the inductance 28.

[0134] The second comparator 52 comprises a subtraction input receiving the value of the current IL flowing in the inductance 28 measured by the current sensor 100 ([Fig.4]).

[0135] An output of the second comparator 52 is connected to an input of the second corrector 53 comprising an output connected to a first input of the control module 54.

[0136] A second input of the module 54 receives a carrier signal S100 of frequency equal to the resonance frequency, for example in square-wave.

[0137] The module 54 comprises a first output connected to the first switches 31, 33 of the first and second switching arms 29, 30, and a second output connected to the second switches 32, 34 of the first and second switching arms 29, 30.

[0138] The first output of the module 54 delivers a first control signal S411 of frequency equal to the resonance frequency and duty cycle Gl, and the second output of the module 54 delivers a second control signal S412 of frequency equal to the resonance frequency and duty cycle c2.

[0139] The duty cycles a1 and a2 are determined so that the estimate of the ballast current is less than or equal to the second threshold S2.

[0140] [Fig.7] illustrates an example of an active compensation method implementing the compensation device.

[0141] During a step 60, the detection means 24 determine whether a current overload is flowing in the filter 15 at a frequency equal to or close to the resonant frequency from the voltage V21 across the terminals of the capacitor 21 and the first and second thresholds SI, S2. A frequency close to the resonance frequency means, for example, that said frequency is included in an interval defined by a lower limit equal to the value of the theoretical resonance frequency provided by the impedances of the filter components minus fifteen percent of the value of the theoretical frequency, and defined by an upper limit equal to the value of the theoretical resonance frequency provided by the impedances of the filter components plus fifteen percent of the value of the theoretical frequency.

[0142] If a current overload is detected, the detection means 24 generate the first signal S241 and the second signal S242 to activate the compensation device.

[0143] When a current overload is detected by the detection means 24, during a precharging step 61, the control means 41 drive the transistors 36 of the switches 31 to 34 to precharge the second inductance 28.

[0144] The control means 41 close the first transistors 31, 33 of the first and second arms 29, 30 and open the second transistors 32, 33 of the first and second arms 29, 30 until the current IL is equal to the precharge current Ipr.

[0145] Alternatively, the control means 41 open the first transistors 31, 33 of the first and second arms 29, 30, and close the second transistors 32, 33 of the first and second arms 29, 30 until the current IL is equal to the precharge current Ipr.

[0146] During a step 62, when the precharging step 61 is finished, the control means 41 drive the transistors 36 of the switches 31 to 34 so that the estimate of the current flowing in the capacitor 21 is less than or equal to the second threshold S2.

[0147] The second inductance 28 delivers the square-shaped compensation current Icomp.

[0148] When the estimate of the current flowing in the capacitor 21 is less than or equal to the second threshold S2, during a step 63, the detection means 41 detect that the current overload is acceptable and generate the second signal S242 for stopping the compensation device. The transistors 36 of the switches 31 to 34 are open.

[0149] Figures 8 and 9 illustrate an example of time evolution of the current through the capacitor 21 during a 3V disturbance of the input voltage of the filter 2 at the resonant frequency of the filter without intervention of the compensation device, and an example of time evolution C20 of the current through the first inductance 21, C21 of the current through the capacitor 21, and C25 of the compensation current Icomp.

[0150] It is noted that the impedance of the filter 2 seen from the power supply 13 is more than doubled by reducing the current overload in the capacity 21 from 100 A peak to less than 40 A peak for a current injected by the current source 25 of approximately 10 A peak.

[0151] The addition of the current source 25 makes it possible to reduce the current overload at the resonance of the filter 15 by increasing the impedance of the filter 15 seen by the power supply 13.

[0152] The compensation current injected by the compensation device is of lower amplitude than the amplitude of the current to be compensated so that the mechanical footprint of the filter 15 is reduced.

[0153] Furthermore, the filter 15 does not require a damping resistor and a device for cooling said resistor, reducing the size of the filter 15.

[0154] Furthermore, the compensation device only operates when a current overload of the capacitor 21 at a frequency equal to or close to the resonant frequency is detected.

[0155] The amplitude of the compensation current Icomp is regulated during operation so as to compensate in particular for the losses of the first inductance 20 and of the other electronic components of the filter 15.

Claims

Claims

1. Method for active compensation of current overload in an input filter (15) of a power converter (12), the input filter being of order at least equal to two, comprising the detection of a current overload in the input filter at the frequency or close to the resonant frequency of the filter from the comparison of an estimate of the current (Ie) flowing in a capacitor (21) of the input filter with a first predetermined threshold, characterized in that the method further comprises: - injecting a compensation current (Icomp) into the input filter by an active compensation current source (25) connected in parallel to the capacitor (21) upon detection of a current overload to reduce the current overload, and - stopping the injection of the compensation current when the current estimate is less than or equal to a second predetermined threshold, the second threshold being less than the first threshold.

2. The method of claim 1, wherein detecting a current overload comprises: - measurement of the voltage across the filter capacitor (21), - filtering the measured voltage by a band-pass filter (45) centered on the resonant frequency of the input filter, - the derivation of the filtered voltage with respect to time to obtain an estimate of the current at resonance passing through the capacitance at resonance of the filter, - the comparison of the current estimate to the first threshold, and - the determination of a current overload if the current estimate is greater than or equal to the first threshold.

3. Method according to one of claims 1 and 2, the active compensation current source (25) comprising an inductance (28), a first switching arm (29) and a second switching arm (30) each connected in parallel with the capacitance (21) of the input filter and each formed by two switches (31, 32, 33, 34) connected in series, the midpoint of each switching arm being connected to a different end of the inductor, wherein the injection of a compensation current comprises: - controlling the switches (31, 32, 33, 34) to precharge the inductor (28) so that the compensation current flowing through the inductor is equal to a predetermined precharge current value, and - when the compensation current (Icomp) is equal to the precharge current value, controlling the switches so that the estimate of the current flowing in the capacitor is less than or equal to the second threshold.

4. The method of claim 3, wherein a first switch (31) of the first switching arm (29) connected to a first end of the capacitor (21) and to a first end of the inductor (28) and a first switch (33) of the second switching arm (30) connected to the second end of the capacitor and to the second end of the inductor are controlled by a first control signal of frequency equal to the resonant frequency of the input filter, and a second switch (32) of the first switching arm (29) connected to the second end of the capacitor and to the first end of the inductor and a second switch (34) of the second switching arm (30) connected to the first end of the capacitor and to the second end of the inductor are controlled by a second control signal of frequency equal to the resonant frequency of the input filter,and wherein controlling the switches comprises adjusting the duty cycle of the first and second signals so that the current flowing in the capacitor is less than or equal to the second threshold.,

5. Active current overload compensation device for an input filter (15) of a power converter (12), the input filter being of order at least equal to two and comprising a capacitor (21), the device being intended to be connected in parallel to the capacitor and comprising detection means (24) configured to detect a current overload in the input filter at the frequency or close to the resonant frequency of the filter from the comparison of an estimate of the current flowing in the capacitor of the input filter with a first predetermined threshold, characterized in that the device further comprises an active compensation current source (25) configured to: - inject a compensation current (Icomp) into the input filter upon detection of a current overload in order to reduce the current overload, and - stop the injection of the compensation current when the current estimate is less than or equal to a second predetermined threshold, the second threshold being less than the first threshold.

6. Device according to claim 5, in which the detection means (24) comprise: - measuring means configured to measure the voltage across the capacitor (21) of the filter, - a bandpass filter (45) centered on the resonant frequency of the input filter configured to filter the measured voltage, - time derivation means (46) configured to obtain an estimate of the current at resonance passing through the capacitor by deriving the filtered voltage with respect to time, and - comparison means (48) configured to compare the estimate of the current with the first threshold and determine a current overload in the input filter if the estimate of the current is greater than or equal to the first threshold.

7. Device according to one of claims 5 and 6, in which the active compensation current source (25) comprises an inductor (28), a first switching arm (29) and a second switching arm (30) each connected in parallel with the capacitor (21) of the input filter and each formed by two switches (31, 32, 33, 34) connected in series, the midpoint of each switching arm being connected to a different end of the inductor, and further comprising control means (41) configured to: - control the switches (31, 32, 33, 34) in order to precharge the inductor so that the compensation current (Icomp) passing through the inductor is equal to a value of predetermined precharge current, - when the compensation current is equal to the value of the precharge current, controlling the switches (31, 32, 33, 34) so that the estimate of the current flowing in the capacitor is less than or equal to the second threshold, and - stopping the injection of the compensation current when the estimate of the current is less than or equal to a second predetermined threshold, the second threshold being less than the first threshold.

8. Device according to claim 7, in which a first switch (31) of the first switching arm (29) is connected to a first end of the capacitor (21) and to a first end of the inductor (28), a first switch (33) of the second switching arm (30) is connected to the second end of the capacitor and to the second end of the inductor, a second switch (32) of the first switching arm (29) is connected to the second end of the capacitor and to the first end of the inductor, and a second switch (34) of the second switching arm (30) is connected to the first end of the capacitor and to the second end of the inductor, the control means (41) being further configured to: - deliver a first control signal of frequency equal to the resonant frequency of the input filter on control inputs of the first switches,- delivering a second control signal of frequency equal to the resonant frequency of the input filter on control inputs of the second switches, and - adjusting the duty cycle of the first and second signals so that the current flowing in the capacitor is less than or equal to the second threshold.,

9. Power converter (12) comprising an input filter (15) intended to be connected to a power supply (13) and comprising a capacitor (21), and an active current overload compensation device according to any one of claims 5 to 8 connected in parallel to the capacity.

10. A motor vehicle (10) comprising a power converter (12) according to claim 9.

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