Electrical power supply circuit of a vehicle electrical energy storage unit

Abstract

Secondary sub-circuit (6) for the electrical power supply circuit (1) of an electrical energy storage unit (2), the secondary sub-circuit (6) being capable of exchanging electrical energy without contact by inductive coupling with a primary sub-circuit (4) capable of being connected to a voltage network (5), the secondary sub-circuit (6) being capable of being connected to an electrical energy storage unit (2), the secondary sub-circuit (6) comprising: - a secondary inductive cell (20) capable of exchanging electrical energy without contact by inductive coupling with the primary sub-circuit (4), - a voltage converter (30) capable of performing impedance matching of the impedance on the AC input of this voltage converter (23), independently of the impedance of the electrical energy storage unit (2),This voltage converter (30) converts the alternating voltage across the secondary inductive cell (20) into at least one intermediate voltage (Vint; Vint1, Vint2), and this voltage converter (30) converts the intermediate voltage into a direct current output voltage (Vbatt) suitable for connection to the terminals of the electrical energy storage unit (2), the value of this direct current output voltage (Vbatt) being lower than that of the intermediate voltage (Vint; Vint1, Vint2). Abbreviated figure: Fig. 1,

Description

Title of the invention: Electrical power supply circuit for a vehicle electrical energy storage unit

[0001] The present invention relates to a contactless power supply circuit for a vehicle electrical energy storage unit.

[0002] The electrical energy storage unit has, for example, a nominal voltage of 12V, 48V, 60V or more, for example greater than 300V, for example 400V, 800V or 1000V.

[0003] It is known to power a vehicle's electrical energy storage unit with a power output between 3 and 50 kW by contactless transmission via inductive coupling, whether the vehicle is stationary or moving. This contactless power supply is achieved using magnetically coupled, distant electrical subcircuits tuned to the same resonant frequency. Each magnetically coupled subcircuit employs an LC-type resonant cell. However, to transmit a satisfactory power level, particularly several kW, it is necessary to operate at high frequencies, specifically on the order of 85 kHz or higher, for the resonant frequency of each resonant subcircuit. Furthermore, this type of solution requires a short distance between the two subcircuits.The frequency and power levels mentioned above, for implementation in kW, can also constitute a danger to the health of people exposed nearby, or a danger to the environment in general.

[0004] The solution according to international application No. PCT / EP2023 / 076297 filed on 22 / 09 / 2023 on behalf of Valeo Systèmes de Contrôle Moteur, which is not part of the published prior art, consists of applying an alternating voltage across the terminals of a primary inductive cell coupled by inductive coupling to a secondary inductive cell which, by impedance matching, allows the transmission of low-frequency electrical energy into an electrical energy storage unit, for example an electric vehicle battery.

[0005] There is a need to provide a power supply to an electrical energy storage unit by contactless transmission which further improves the known solutions.

[0006] The invention aims to meet this need and achieves this, according to one of its aspects, by means of a secondary sub-circuit for the power supply circuit of an electrical energy storage unit, the secondary sub-circuit being capable of exchanging electrical energy without contact by inductive coupling with a sub- primary circuit suitable for connection to a voltage network, the secondary sub-circuit being suitable for connection to an electrical energy storage unit, the secondary sub-circuit comprising:

[0007] - a secondary inductive cell capable of contactless exchange via inductive coupling electrical energy with the primary sub-circuit,

[0008] - a voltage converter capable of performing impedance matching of the impedance on the AC input of this voltage converter, independent of the impedance of the electrical energy storage unit, this voltage converter converting the AC voltage across the terminals of the secondary inductive cell into at least one intermediate voltage, and this voltage converter converting the intermediate voltage into a DC output voltage suitable for connection to the terminals of the electrical energy storage unit, the value of this DC output voltage being lower than that of the intermediate voltage.

[0009] The secondary subcircuit described above enables impedance matching when the voltage across the secondary inductive cell exceeds the voltage of the electrical energy storage unit. This allows medium- or low-voltage electrical energy storage units to be charged without increasing the number of turns, and therefore the weight and cost, of the primary subcircuit. This provides a simple and inexpensive way to extend the ability to perform impedance matching for transmitting low-frequency electrical energy to an electrical energy storage unit, for electrical energy storage units with nominal voltages of 12V, 48V, 60V, or even up to and including 200V, or even 300V.

[0010] According to a first embodiment, the voltage converter may comprise an inverter / rectifier including at least two parallel switching arms, each switching arm comprising two electronic switches arranged on either side of a midpoint, and each terminal of the secondary inductive cell is connected to a respective midpoint, the voltage across the arms defining the intermediate voltage. The converter further comprises a step-down converter converting the DC intermediate voltage into the DC output voltage. This step-down converter includes at least one switching arm comprising two electronic switches arranged on either side of a midpoint. The midpoint of this arm is, for example, connected via an inductor to an output terminal whose potential difference with ground constitutes the DC output voltage.

[0011] According to this first example, the voltage converter comprises two components mounted in cascade, namely the inverter / rectifier and the step-down voltage converter.

[0012] One of the two arms of the inverter / rectifier is, for example, controlled to switch at the frequency of the electrical energy exchanged without contact by inductive coupling and with a duty cycle of 50%, and the other of the two arms of the inverter / rectifier is then controlled to switch at a frequency higher than that of said electrical energy and with a duty cycle modulated according to the alternating current flowing in the secondary inductive cell and the voltage on the AC input of this inverter / rectifier. In one example, this duty cycle is expressed using the following expression:

[0013] oc=(RRef xlll ) / Vint

[0014] where:

[0015] - Vint designates the intermediate voltage,

[0016] -1 designates the current flowing in the secondary inductive cell,

[0017] - RRef is the equivalent impedance at the AC input of the inverter / rectifier, RRef being equal to the ratio V / I where V is the voltage between the two midpoints of the inverter / rectifier.

[0018] When the two switching arms of the inverter / rectifier are controlled as above, the step-down converter can apply a duty cycle chosen to impose an intermediate voltage value higher than that of the DC output voltage. This duty cycle is, for example, between 2% and 98%.

[0019] Alternatively, the inverter / rectifier switching arms are controlled at low frequency to bias the voltage on the AC input of the inverter / rectifier, and the step-down converter switching arm is controlled to switch at high frequency to impose the value of the intermediate voltage. According to this embodiment, the intermediate voltage may have a rectified sine wave.

[0020] The step-down converter is, for example, a series chopper. Other examples of step-down converters are possible.

[0021] The ratio between the value of the intermediate voltage and the value of the DC output voltage of the converter can be between 1.5 and 200.

[0022] According to the first embodiment, the converter may comprise three switching arms, namely: two switching arms for the inverter / rectifier, and one switching arm for the step-down converter. These three arms switching units can be mounted in parallel, having the intermediate voltage as their common voltage.

[0023] The voltage converter according to this first embodiment comprises, for example, only three switching arms. In this case, the voltage converter preferably comprises only six controllable electronic switches, for example, MOSFET field-effect transistors or IGBT transistors. In a variant in which the converter comprises only six electronic switches, not all of them are controllable. The switching arm of the step-down converter comprises, for example, one controllable electronic switch and one non-controllable electronic switch, such as a diode.

[0024] According to a second embodiment of the invention, the voltage converter comprises:

[0025] - a first input terminal connected to a terminal of the inductive cell secondary,

[0026] - a second input terminal connected to the other terminal of the inductive cell secondary,

[0027] - a first switching arm disposed between the first input terminal and the mass and comprising two electronic switches arranged on either side of a first midpoint,

[0028] - a second switching arm disposed between the second input terminal and the mass and comprising two electronic switches arranged on either side of a second midpoint, and

[0029] - an output terminal disposed between the first and second midpoints,

[0030] two intermediate voltages being defined, each intermediate voltage being defined between an input terminal of the converter and ground, and the DC output voltage being defined between the output terminal and ground.

[0031] According to this second embodiment, the voltage converter may comprise only two switching arms. The voltage converter is then not formed by cascading two components, unlike the voltage converter according to the first embodiment. This results in savings in cost, efficiency, and size for the voltage converter.

[0032] Each intermediate voltage is, for example, a voltage whose variable value remains greater than or equal to the value of the DC output voltage. Each switching arm of the voltage converter is, for example, controlled so that each intermediate voltage remains positive and always takes a value greater than or equal to the DC output voltage. The control of the switching arms can allow the values ​​of the intermediate voltages to be controlled.

[0033]

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]

[0040]

[0041]

[0042]

[0043]

[0044]

[0045] in order to emulate an RRefSur impedance at the AC input of the voltage converter. According to the second implementation example: - a first capacitor can be mounted between the first input terminal of the converter and ground, and - a second capacitor can be mounted between the second input terminal of the converter and ground. Each of these two capacitors can maintain the respective intermediate voltage despite the presence of a high-frequency effective current. According to this second implementation example, each electronic switch of the voltage converter can be controllable, such as a Mosfet or IGBT type field-effect transistor. According to the second implementation example, the output terminal can be connected to the first midpoint via a first inductor, and this output terminal can be connected to the second midpoint via a second inductor. Both of these inductors can be made using a single magnetic core around which two separate windings are wound. Alternatively, each of these two inductors has its own core. If necessary, each inductor is formed by two coupled sub-inductors. When the voltage converter consists only of electronically controllable switches, the two electronically controllable switches of the first arm can be controlled using a first duty cycle a3 and the two electronically controllable switches of the second switching arm can be controlled using a second duty cycle a4, and these two duty cycles are determined as follows: a3 = 0.5 - X [Math.l] a4 = 0.5 + X X being a parameter determined as a function of the voltage Vbatt across the terminals of the electrical energy storage unit, the current I flowing in the secondary inductive cell, and the equivalent impedance RRef across the terminals of the secondary inductive cell, RRef being equal to the ratio V / I where V is the voltage across the terminals of the secondary inductive cell. This allows us to emulate a high value for RRef. X is obtained, for example, according to the equation below

[0046] In all the above, the secondary inductive cell can be constituted by the series association of a capacitor and an inductor.

[0047] Alternatively, the secondary inductive cell may consist of an inductor, with two switching arms of the converter, which are the two switching arms of the inverter / rectifier of the converter according to the first embodiment, being controlled such that the voltage across the AC input of this inverter / rectifier emulates the presence of a capacitor connected in series with the secondary inductive cell. Such control for obtaining this emulation is described in the application filed in France on June 2, 2023, by the Applicant under number 23 05573. The content of this application is incorporated by reference into the present application with regard to the control of the duty cycles of the switching arms of the inverter / rectifier.

[0048] The contactless exchange of electrical energy by inductive coupling can be carried out at a frequency below 5 kHz, for example below 3 kHz, or even below 2 kHz or 1 kHz, notably still approximately equal to 400 Hz or 50 Hz. In this case, the inductance of the secondary inductive cell can be made of metallic wire, such as copper. Such a metallic wire is solid, as opposed to Litz wire. A solid metallic wire does not have a hollow cross-section. Alternatively, this inductance of the secondary inductive cell is made of Litz wire.

[0049] The invention can, however, also be applied if the contactless exchange of electrical energy by inductive coupling takes place at a frequency between 79 kHz and 90 kHz, for example, 85 kHz. In this embodiment, Litz wire is advantageously used to create the inductance of the secondary inductive cell.

[0050] In all the foregoing, the secondary sub-circuit may include the electrical energy storage unit. This unit may be a lithium-ion battery. This battery may, for example, have a nominal voltage of 12V, 48V, 60V or more, for example, up to 200V, or even up to 300V. The electrical energy storage unit is used for the electric propulsion of a vehicle. This vehicle is, for example, a vehicle classified as a "small mobility vehicle," such as an electric bicycle, an electric tricycle, an electric scooter, or an electric motorcycle. More generally, the invention applies to any form of electric mobility, whether it be a vehicle traveling on land with four, three, two, or any other number of wheels, or a vehicle moving in the air or on water.

[0051] The invention also relates, according to another aspect, to an electrical power supply circuit for an electrical energy storage unit, this electrical power supply circuit comprising:

[0052] - a primary sub-circuit, suitable for connection to a voltage network, and

[0053] - the secondary sub-circuit, connected to the electrical energy storage unit, the secondary sub-circuit being as defined above,

[0054] the primary sub-circuit and the secondary sub-circuit being configured so as to exchange electrical energy without contact by inductive coupling.

[0055] In all that follows, the primary subcircuit may include:

[0056] - a primary inductive cell for contactless exchange by inductive coupling of electrical energy with the secondary inductive cell, and

[0057] - an inverter / rectifier comprising at least two switching arms, each switching arm comprising two electronic switches controllable on either side of a midpoint.

[0058] The secondary inductive cell and the primary inductive cell are advantageously chosen so that they have the same resonant frequency.

[0059] In all the foregoing, the primary inductive cell may be constituted by the series combination of a capacitor and an inductor. Alternatively, the primary inductive cell may be constituted by an inductor, the switching arms of the inverter / rectifier of the primary subcircuit being controlled such that the voltage across the AC input of this inverter / rectifier emulates the presence of a capacitor connected in series with the primary inductive cell. Such control for obtaining this emulation is described in the application filed in France on June 2, 2023, by the Applicant under number 23 05573. The content of this application is incorporated by reference into the present application with regard to the control of the duty cycles of the switching arms of the inverter / rectifier.

[0060] In the case of a contactless exchange of electrical energy by inductive coupling at a frequency below 5 kHz, the inductance of the primary inductive cell can be made of metallic wire, such as copper. Such a metallic wire is solid, as opposed to Litz wire. A solid metallic wire does not have a hollow cross-section. Alternatively, this inductance of the primary inductive cell is made of Litz wire.

[0061] If necessary, the primary sub-circuit may include another inverter / rectifier mounted upstream of the inverter / rectifier at the midpoints of which the transformer's primary winding is mounted. This other inverter / rectifier rectifies the AC voltage received from the grid when the load is drawn from an AC voltage grid. This other inverter / rectifier can then perform a power factor correction function. Such a correction ensures, in a known manner, that the current drawn from the grid is as close as possible to a perfect sine wave at the grid frequency. This reduces reactive current and subharmonics, which increase energy losses during conduction.

[0062] In all the above, the electrical network supplies, for example, a nominal effective voltage of 230V with a frequency of 50 Hz or 60 Hz. The electrical network is, for example, single-phase. The electrical network is, for example, a regional or national electrical network. Alternatively, it may be an independent local network, comprising, for example, one or more batteries powered by energy sources such as wind turbines, solar panels, fuel cells, or hydroelectric generators.

[0063] Alternatively, the electrical network can supply a direct current voltage.

[0064] The electrical circuit may include a control unit configured to control the switching arms of the primary and / or secondary sub-circuit. According to the present invention, when an arm switches, each of its two controllable electronic switches is opened and closed in a complementary manner with the same switching frequency.

[0065] In all the above, the control unit can be configured to control the different switching arms so as to selectively perform:

[0066] - a charge of the electrical energy storage unit from the voltage network, Or

[0067] - a load from the voltage network from the electrical energy storage unit.

[0068] Thus, depending on the need, the exchange of electrical energy can take place in one direction or the other.

[0069] In all the above, each controllable electronic switch is, for example, bidirectional.

[0070] In all the foregoing, the control unit may be a digital processing circuit, for example an ASIC (Application-specific integrated circuit) or a microcontroller. This control unit may control all the switching arms of the electrical circuit, whether they belong to the primary or secondary subcircuit.

[0071] The control unit may alternatively include a primary sub-circuit control module and a secondary sub-circuit control module.

[0072] Alternatively, each sub-circuit has its own control unit, the latter being a digital processing circuit such as a microcontroller.

[0073] The invention also relates, according to another aspect, to a component for the power supply of an electrical energy storage unit, comprising the electrical circuit as defined above, the component defining in particular a structure rigidly coupled to each other supporting the primary sub-circuit and the secondary sub-circuit. Such a component is commonly called a "charger". "On-board charger". This component is suitable for use in a hybrid or electric vehicle.

[0074] The invention also relates, according to another aspect, to a device for supplying power to an electrical energy storage unit, comprising:

[0075] - a charging station for hybrid or electric vehicles, in which is arranged the primary sub-circuit of the electrical circuit as defined above, or to which this primary sub-circuit is electrically connected, and

[0076] - a component suitable for being installed in a hybrid or electric vehicle, in which is arranged the secondary sub-circuit of the electrical circuit as defined above.

[0077] This terminal then receives electrical energy from an electrical network via a cable, which can be a single-phase or three-phase cable. In this case, the primary and secondary circuits are not integrated into the same physical component.

[0078] The invention will be better understood upon reading the following description of a non-limiting example of its implementation and upon examination of the accompanying drawing in which:

[0079] [Fig-1] schematically represents an electrical power supply circuit according to a first example of implementation of the invention, and

[0080] [Fig.2] represents the secondary sub-circuit according to a second example of implementation work of invention.

[0081] Figure 1 shows a power supply circuit 1 for an electrical energy storage unit 2. This electrical energy storage unit 2 is, for example, a vehicle battery, which may have a nominal voltage of 48V, 60V, or up to 200V. This battery is used to power a propulsion system for an electric or hybrid vehicle. The vehicle is, for example, a vehicle classified as a "small mobility vehicle," such as an electric bicycle, an electric tricycle, an electric scooter, or an electric motorcycle.

[0082] This power supply circuit 1 comprises:

[0083] - a control unit 3,

[0084] - a primary sub-circuit 4, suitable for connection to a voltage network 5, and

[0085] - a secondary sub-circuit 6, comprising the electrical energy storage unit 2.

[0086] The power supply circuit 1 implements a contactless exchange of electrical energy by inductive coupling between the primary sub-circuit 4 and the secondary sub-circuit 6, for the charging of the electrical energy storage unit 2.

[0087] The control unit 3 is for example a microcontroller or any digital processing unit.

[0088] In the example considered, the primary sub-circuit 4 comprises:

[0089] - a connector 9 suitable for being connected to the electrical network,

[0090] - an inverter / rectifier 21 comprising here two switching arms 7, mounted in parallel, and whose operation will be described below, and

[0091] - a primary inductive cell 10 whose operation will be described below.

[0092] The electrical network 5 is represented here in the form of a voltage network The network may be continuous, but alternatively, it may be an alternating voltage network supplying, for example, a nominal RMS voltage of 230V with a frequency of 50 Hz or 60 Hz. Such an alternating voltage network can be single-phase or three-phase. Other voltages are possible, for example, a single-phase RMS voltage of 120V and a frequency of 60 Hz, a two-phase RMS voltage of 208V and a frequency of 60 Hz, or a three-phase voltage of 240V and a frequency of 60 Hz; this list is not exhaustive. If the network supplies alternating voltage, another inverter / rectifier (not shown) is provided between the network and the inverter / rectifier 21. This other inverter / rectifier performs, for example, a power factor correction function.

[0093] As can be seen in [Fig. 1], a capacitor 15 can be arranged in parallel with the two switching arms 7. The latter has, for example, a capacitance between IpF and ImF, for example of lOpF.

[0094] Each arm 7 of the primary subcircuit 4 here comprises two controllable electronic switches 12, such as MOS, IGBT or bipolar transistors, or thyristors, arranged on either side of a midpoint 8. The two switches 12 of the same switching arm 7 are here controlled using the same duty cycle, one in opposition to the other with a dead time by the control unit 3.

[0095] The first arm 7 thus comprises two controllable electronic switches 12 and a first midpoint 8 to which a terminal of the primary inductive cell 10 is connected, and these two controllable electronic switches 12 are controlled according to a duty cycle ab

[0096] The second arm 7 thus comprises two controllable electronic switches 12 and a second midpoint 8 to which the other terminal of the primary inductive cell 10 is connected and these two controllable electronic switches 12 are controlled according to a duty cycle a2.

[0097] In the example considered, no physical component is interposed between the two midpoints 8 of the inverter / rectifier 21 and the primary inductive cell 10.

[0098] The primary inductive cell 10 can be formed by combining in series: an inductor for generating magnetic energy, and a capacitor, to form a resonant cell. The inductor has, for example, a value between 10H and 10MH and the capacitor has a capacitance between 10 nF and 1 mF. The inductor is, for example, made by winding a copper wire, other than Litz wire.

[0099] In the variant shown in [Fig. 1], the primary inductive cell 10 is formed by an inductance only. No physical capacitor is present; the presence of this capacitor in series with the inductance of the primary inductive cell 10 is emulated by the control of the switching arms 7 by the primary control unit 3 using the duty cycles ai and a2. Here again, the inductance is, for example, made by winding a copper wire.

[0100] We will now describe a first example of the implementation of a secondary sub-circuit 6 with reference to [Fig. 1]. This secondary sub-circuit 6 includes a secondary inductive cell 20 for the exchange of energy without contact with the primary inductive cell 10, and a voltage converter 30 for generating a DC output voltage Vbatt suitable for connection to the terminals of the electrical energy storage unit 2.

[0101] According to this first example of implementation, the voltage converter 30 comprises in cascade:

[0102] - an inverter / rectifier 23, capable of performing impedance matching equivalent on its AC input (i.e., on the side of the secondary inductive cell 20), so as to vary this impedance independently of the impedance of the electrical energy storage unit 2, and

[0103] - a step-down voltage converter 31.

[0104] The inverter / rectifier 23, when operating in rectifier mode, allows the rectifie the voltage induced across the terminals of the secondary inductive cell 20 into a direct voltage Vint. The inverter / rectifier 23 in the described example comprises two switching arms 24 arranged in parallel, each arm comprising two controllable electronic switches 12 arranged on either side of a midpoint 25.

[0105] The two switches 12 of the same switching arm 24 are here controlled using the same duty cycle, one in opposition to the other with a dead time by the control unit 3.

[0106] The first arm 24 thus comprises two controllable electronic switches 12 and a first midpoint 25 to which a terminal of the secondary inductive cell 20 is connected and these two controllable electronic switches 12 are controlled according to a duty cycle a3.

[0107] The second arm 24 thus comprises two controllable electronic switches 12 and a second midpoint 25 to which the other terminal of the secondary inductive cell 20 is connected and these two controllable electronic switches 12 are controlled according to a duty cycle a4.

[0108] The secondary inductive cell 20 is formed, for example, by the series connection of an inductor for recovering the magnetic energy from the primary inductive cell 10, and a capacitor, thus forming a resonant cell. In the example considered, the inductance has a value between ImH and 100mH and the capacitor has a capacitance between 100pF and 100mF. The inductance is, for example, made by winding a copper wire, other than Litz wire.

[0109] In the variant shown in [Fig. 1], the secondary inductive cell 20 is formed by an inductance only. No physical capacitor is present; the presence of this capacitor in series with the inductance of the secondary inductive cell 20 is emulated by the control of the switching arms 24 by the primary control unit 3 using the duty cycles a3 and a4. Here again, the inductance is, for example, made by winding a copper wire.

[0110] Furthermore, the control unit 3 acts in the described example on the control of the inverter / rectifier 23 in such a way as to vary the equivalent impedance RRef across the terminals of the AC input, defined between the two midpoints 25 of the switching arms 24, independently of the impedance on the DC output of this inverter / rectifier 23.

[0111] The equivalent impedance RRef is represented by the ratio V / I where V is the voltage between the two midpoints 25, and I is the intensity of the current flowing in the secondary inductive cell 20.

[0112] RRef, for example, has a value between 0.1 'Q and 20 'Q, in particular between 5 'Q and 15 'Q. For a given charging configuration, this configuration being determined in particular by at least one of the following: the position of the secondary sub-circuit 6 relative to the primary sub-circuit 4 and / or the power level to be transmitted and / or the voltage across the terminals of the electrical energy storage unit 2, RRef may have a fixed value, and this value is, for example, within the aforementioned range. From one charging configuration to another, for example in the case of a greater distance between the primary sub-circuit 4 and the secondary sub-circuit 6 and / or to take into account the aging of the system, the value of RRef may be modified, remaining in particular within the aforementioned range.

[0113] The inverter / rectifier 23 of [Fig. 1] is, for example, controlled as follows by the control unit 3, to perform impedance matching on the AC input of the inverter / rectifier 23:

[0114] - one of the two switching arms 24 switches at the energy frequency electrical current exchanged without contact via inductive coupling and with a duty cycle a3 of 50%, and

[0115] - the other of the two switching arms 24 switches at a higher frequency to that of the electrical energy exchanged without contact, for example at least 5 times or 10 times this frequency of the electrical energy exchanged without contact, and with a duty cycle a4 modulated according to the alternating current flowing in the secondary inductive cell 20 and according to the voltage across the AC input of the inverter / rectifier 23. One of the controllable switches 12 of the switching arm 24 which switches at a frequency higher than that of the electrical energy exchanged without contact is for example controlled according to the duty cycle a4 while the other controllable switch of this arm 24 is controlled according to the duty cycle 1- a4, and a4 is for example determined according to the equation below:

[0116] oc4 =(Rref xlll ) / Vint

[0117] where Vint designates the intermediate DC voltage across the terminals of the two switching arms 24.

[0118] Figure 1 shows that a capacitor 27 is mounted in parallel with the two switching arms 24. This capacitor 27 is mounted in parallel with a switching arm 33 of the step-down converter 31. The switching arm 33 comprises two electronic switches 35 arranged on either side of a midpoint 36. As can be seen in Figure 1, the midpoint 36 of this arm 33 is connected via an inductor 37 to an output terminal, the potential difference of which with ground constitutes the DC output voltage Vbatt. The DC output voltage Vbatt is applied to a capacitor 39 mounted in parallel with the electrical energy storage unit 2.

[0119] The step-down voltage converter 31 of [Fig. 1] is, for example, controlled as follows by the control unit 3, to lower the voltage Vint into the DC output voltage Vbatt so that Vbatt is equal to a5 times Vint where a3 is between 2 / 3 and 1 / 200:

[0120] - one of the electronic switches 35 of the switching arm 33 is controlled according to the cyclical ratio a5

[0121] - the other electronic switch 33 is controlled according to the duty cycle l-a5.

[0122] The voltage converter 30 of [Fig. 1] thus makes it possible to carry out an adaptation impedance when the voltage induced across the terminals of the secondary inductive cell 20 is greater than the DC output voltage Vbatt.

[0123] According to the first embodiment, the electronic switches 35 of the switching arm 33 are not necessarily all controllable. In an example not shown but covered by the invention, the buck converter 31 is a series chopper, and one of the electronic switches 35 of the switching arm 33 is then a diode.

[0124] We will now describe, with reference to [Fig. 2], a secondary subcircuit 6 according to a second embodiment of the invention, this secondary subcircuit 6 interacting with a primary subcircuit 4 which is identical to that described with reference to [Fig. 1] and not shown in [Fig. 2] for clarity. The secondary subcircuit 6 of [Fig. 2] is, for example, always controlled by the control unit 3.

[0125] According to this second embodiment of the invention, the voltage converter 30 comprises:

[0126] - a first input terminal 40 connected to a terminal of the inductive cell Secondary 20,

[0127] - a second input terminal 41 connected to the other terminal of the inductive cell Secondary 20,

[0128] - a first switching arm 44 disposed between the first input terminal 40 and the mass and comprising two electronic switches 12 arranged on either side of a first midpoint 45,

[0129] - a second switching arm 44 disposed between the second input terminal 41 and the mass and comprising two electronic switches 12 arranged on either side of a second midpoint 45, and

[0130] - an output terminal 46 disposed between the first and second midpoint 45.

[0131] It can thus be seen that the voltage converter 30 according to this second example The implementation includes only two switching arms, namely the switching arms 44. According to this second implementation example, two intermediate voltages Vintl and Vint2 are defined, Vintl being the voltage across the first switching arm 44 and Vint2 being the voltage across the second switching arm 44.

[0132] The voltage converter 30 according to this second embodiment also includes two capacitors 48 and 49, each capacitor 48,49 being mounted in parallel with a respective switching arm 44.

[0133] The output terminal 46 defines with ground the continuous output voltage Vbatt which is applied to the electrical energy storage unit 2.

[0134] It is also observed in the example considered that the output terminal 46 is connected to each midpoint 45 of a switching arm 44 via an inductance 50, 51. The inductance 50 is thus mounted between the output terminal 46 and the midpoint 45 of the first switching arm 44, and the inductance 51 is mounted between the output terminal 46 and the midpoint 45 of the second switching arm 44. The two inductances 50 and 51 are, for example, wound on a common core.

[0135] According to this second embodiment, each electronic switch 12 of a switching arm 44 is controllable. This is, for example, a field-effect transistor such as a MOSFET or an IGBT.

[0136] In the example considered, each intermediate voltage Vinti and Vint2 is a voltage whose variable value remains greater than or equal to the value of the DC output voltage Vbatt- For this purpose, each switching arm 44 of the voltage converter 30 is controlled so that each intermediate voltage Vinti, Vint2 remains positive and always takes a value greater than or equal to the DC output voltage Vbatt.

[0137] This control of the switching arms 44 consists, for example, of using a first duty cycle a3 for the first switching arm 44 and a second duty cycle a4 for the second switching arm, these two duty cycles being determined as follows

[0138] a3 = 0.5-X

[0139] [Math.4] (z4 — 0.5+V

[0140] X being a parameter determined as a function of the DC output voltage Vbatt across the terminals of the electrical energy storage unit 2, the current I flowing in the secondary inductive cell 20, and the equivalent impedance RRef across the terminals of the secondary inductive cell 20, RRef being equal to the ratio V / I where V is the voltage across the terminals of the secondary inductive cell 20.

[0141] X is obtained, for example, according to the equation below [° 142 1 Y 'V ' > -rVbM

[0143] One of the controllable switches 12 of the first switching arm 44 is for example controlled according to the duty cycle a3 while the other controllable switch of this arm 44 is controlled according to the duty cycle 1- a3.

[0144] One of the controllable switches 12 of the second switching arm 44 is for example controlled according to the duty cycle a4 while the other controllable switch of this arm 44 is controlled according to the duty cycle 1- a4.

Claims

1. Demands Secondary sub-circuit (6) for the electrical power supply circuit (1) of an electrical energy storage unit (2), the secondary sub-circuit (6) being capable of exchanging electrical energy without contact by inductive coupling with a primary sub-circuit (4) capable of being connected to a voltage network (5), the secondary sub-circuit (6) being capable of being connected to an electrical energy storage unit (2), the secondary sub-circuit (6) comprising: - a secondary inductive cell (20) capable of exchanging electrical energy without contact by inductive coupling with the primary sub-circuit (4), - a voltage converter (30) capable of performing impedance matching of the impedance on the AC input of this voltage converter (23), independently of the impedance of the electrical energy storage unit (2),this voltage converter (30) converting the alternating voltage across the terminals of the secondary inductive cell (20) into at least one intermediate voltage (Vint), and this voltage converter (30) converting the intermediate voltage into a direct output voltage (Vbatt) suitable for connection to the terminals of the electrical energy storage unit (2), the value of this direct output voltage (Vbatt) being less than that of the intermediate voltage (Vint), the voltage converter (30) comprising an inverter / rectifier (23) comprising at least two parallel switching arms (24), each switching arm comprising two electronic switches (12) arranged on either side of a midpoint (25), and each terminal of the secondary inductive cell being connected to a respective midpoint, the voltage across the arms defining the intermediate voltage (Vint),the voltage converter (30) further comprising a step-down voltage converter (31) converting the intermediate voltage (Vint) into the DC output voltage (Vbatt), one of the two arms of the inverter / rectifier (23) being controlled to switch at the frequency of the electrical energy exchanged without contact by inductive coupling and with a duty cycle of 50%, and the other of the two arms of the inverter / rectifier (23) being controlled to switch at a frequency higher than that of said energy,

2.

3.

4.

5. electrical and with a duty cycle modulated according to the alternating current (I) flowing in the secondary inductive cell (20) and the voltage (V) on the alternating input of this inverter / rectifier (23). Secondary subcircuit according to claim 1, the step-down voltage converter (31) being a series chopper. Secondary sub-circuit according to any one of the preceding claims, the ratio between the value of the intermediate voltage (Vint) and the value of the DC output voltage (Vbatt) of the converter being between 1.5 and 200. Secondary subcircuit according to any one of the preceding claims, the voltage converter (30) comprising exactly three switching arms (24, 33). Secondary sub-circuit (6) for the power supply circuit (1) of an electrical energy storage unit (2), the secondary sub-circuit (6) being capable of exchanging electrical energy without contact by inductive coupling with a primary sub-circuit (4) capable of being connected to a voltage network (5), the secondary sub-circuit (6) being capable of being connected to an electrical energy storage unit (2), the secondary sub-circuit (6) comprising: - a secondary inductive cell (20) capable of exchanging electrical energy without contact by inductive coupling with the primary sub-circuit (4), - a voltage converter (30) capable of performing impedance matching of the impedance at the AC input of this voltage converter (30), independently of the impedance of the electrical energy storage unit (2), this voltage converter (30) converting the AC voltage across the secondary inductive cell (20) into at least one intermediate voltage (Vinti, Vint2), and this voltage converter (30) converting the intermediate voltage into a DC output voltage (Vbatt) suitable for connection to the terminals of the electrical energy storage unit (2), the value of this DC output voltage (Vbatt) being lower than that of the intermediate voltage (Vinti, Vint2), the voltage converter (30) comprising: - a first input terminal (40) connected to a terminal of the secondary inductive cell (20), - a second input terminal (41) connected to the other terminal of the secondary inductive cell (20), - a first switching arm (44) disposed between the first input terminal (40) and ground and comprising two electronic switches (12) disposed on either side of a first midpoint (45), - a second switching arm (44) disposed between the second input terminal (41) and ground and comprising two electronic switches (12) disposed on either side of a second midpoint (45), and - an output terminal (46) disposed between the first and second midpoints (45), two intermediate voltages (Vinti, Vint2) being defined, each intermediate voltage (Vinti, Vint2) being defined between an input terminal (40, 41) of the voltage converter and ground, and the DC output voltage (Vbatt) being defined between the output terminal (46) and ground,the two electronic switches (12) of the first switching arm (44) being controllable and controlled using a first duty cycle a3 and the two electronic switches (12) of the second switching arm (44) being controllable and controlled using a second duty cycle a4, and these two duty cycles being determined as follows a3 = 0.5-X [Math.7] a4 = 0.5+XX being a parameter determined as a function of the DC output voltage (Vbatt) across the terminals of the electrical energy storage unit, the current I flowing in the secondary inductive cell, and the equivalent impedance RRef across the terminals of the secondary inductive cell, RRef being equal to the ratio V / I where V is the voltage on the AC input of the converter (30).

6. Secondary subcircuit according to claim 5, each intermediate voltage (Vinti, Vint2) being a voltage whose value varies remains greater than or equal to the value of the DC output voltage (Vbatt).

7. Secondary subcircuit according to claim 5 or 6, the output terminal (46) being connected to the first midpoint (45) via a first inductor (50) and this output terminal (46) being connected to the second midpoint (45) via a second inductor (51).

8. Secondary subcircuit according to any one of claims 5 to 7, the voltage converter (30) comprising only two switching arms (24).

9. Secondary subcircuit according to any one of the preceding claims, the secondary inductive cell (20) being constituted by the series association of a capacitor and an inductor.

10. Power supply circuit (1) of an electrical energy storage unit (2), said power supply circuit comprising: - a primary sub-circuit (4), suitable for connection to a voltage network, and - the secondary sub-circuit according to any one of the preceding claims, connected to the electrical energy storage unit (2), the primary sub-circuit (4) and the secondary sub-circuit (6) being configured so as to exchange electrical energy without contact by inductive coupling

11. Device for supplying power to an electrical energy storage unit (2), comprising: - the electrical circuit according to claim 10, - a charging station for a hybrid or electric vehicle, in which the primary sub-circuit (4) of the electrical circuit (1) is disposed or to which the primary sub-circuit (4) is connected, and - a component suitable for being carried in a hybrid or electric vehicle, in which the secondary sub-circuit (6) of the electrical circuit (1) is disposed.

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