FR3099311A1 - Contactless power transmission device by inductive resonance coupling for recharging a motor vehicle - Google Patents

Abstract

Contactless power transmission device by inductive resonance coupling for recharging a motor vehicle Device (100) for contactless power transmission by inductive resonance coupling, in particular for charging or recharging a motor vehicle with electrical energy, comprising: a source of 'energy (10), in particular alternating current, a resonant emitting circuit (1) comprising a first capacitance (C1) and a first winding (E1), the first winding (E1) comprising an inductance and a first resistance, the resonant circuit emitter (1) being supplied by the energy source (10), a receiver resonant circuit (2) comprising a second capacitance (C2) and a second winding (E2), the second winding (E2) comprising a second inductor, a second resistor, the receiving resonant circuit (2) further comprising a control inductor, characterized in that the inductance value of the control inductor varies e in a predetermined manner. Figure for abstract: Figure 1

Description

Contactless power transmission device by resonant inductive coupling for recharging a motor vehicle

The present invention relates to a receiver resonant circuit and to a contactless power transmission device by resonant inductive coupling for charging or recharging a motor vehicle or any type of vehicle propelled by means of electrical energy.

In a manner known per se, it is technically possible to supply by contactless transmission a motor vehicle or any other object equipped with an electrical energy storage device at a power of between 3 and 10 kW, when this object is at stopping (we speak in this case of static load), or when it moves (we then speak of dynamic load. This power supply by contactless transmission is then done by means of remote electrical circuits magnetically coupled and tuned to the same frequency The magnetically coupled circuits each comprising at least one resonant LC element, L and C respectively designating inductors and capacitances.

The problem with this type of solution is that to transmit a satisfactory level of power, in particular several kW, it is necessary to operate at high frequencies, in particular of the order of 85 kHz or more, for the working frequency and for the natural frequency. of each resonant circuit. In addition, this type of solution requires operating at a short distance between the resonant elements located at the source and at the load.

Operating at such a high frequency level results mainly in the need to use expensive components such as soft ferrites and Litz conductive wire whose strands are of very small section, for example less than or equal to 0.07 mm in diameter. diameter.

The object of the invention is to overcome, at least in part, these drawbacks.

To this end, the subject of the invention is a resonant receiver circuit for carrying out contactless power transmission by resonant inductive coupling with a resonant transmitter circuit comprising a first capacitance and a first winding, the first winding comprising a first inductance and a first resistance,

• the resonant receiver circuit comprising a second capacitance of value C2' and a second winding, the second winding comprising a second inductance of value L2', a second resistor of value R2', the resonant receiver circuit further comprising a value control inductance L2f' connected in series with the second inductor,
• the receiver resonant circuit having a natural pulsation ω2 such that ω2=1/√((L2'+L2f') x C2') and a natural frequency f2 such that f2 = ω2 / (2π),
• characterized in that the inductance value of the control inductor varies in a predetermined manner.

According to one implementation, the control inductance is formed by an electronic voltage inverter, in particular arranged to emulate the electrical behavior of the control inductance and the value of the inductance L2f′.

The invention makes it possible to increase the amplitude of an electric ignition current supplied by the resonant transmitter circuit to the resonant receiver circuit, when the resonant transmitter circuit is magnetically coupled to the resonant receiver circuit.

According to one implementation, the electronic voltage inverter comprises power components, for example IGBT type transistors forming at least two arms.

According to one implementation, the electronic voltage inverter delivers an AC voltage controlled by means of a DC control voltage.

According to one implementation, the electronic voltage inverter has two connection terminals between which the alternating voltage is delivered, these two connection terminals being the two terminals between which the control inductance is emulated.

According to one implementation, the DC control voltage is ensured by a power supply able to deliver a power greater than or equal to the power to be transmitted by the inductive resonant coupling.

According to one implementation, the inductance value of the control inductor varies according to a predetermined frequency and according to a predetermined inductance variation amplitude hL around an average value L2moy, so that the proper pulsation varies according to a amplitude of variation of pulsation hω predetermined around a mean value ω2moy, with ω2moy = 1/√((L2′+L2moy)×C2′).

The invention thus makes it possible to achieve an amplification of the amplitude of the current and of the voltage, at the level of the resonant receiver circuit, with a sufficiently high amplification gain to make it possible to operate at a lower frequency, and/or at a greater distance.

According to one implementation, the predetermined frequency is chosen so as to increase the amplitude of the electric current flowing in the receiver resonant circuit, increasing exponentially.

The invention thus makes it possible, by introducing an amplification gain, to transmit a satisfactory level of power by a contactless method between a resonant transmitter circuit and a resonant receiver circuit, despite the implementation of a frequency very low compared to the state of the art.

According to one implementation, the inductance value L2f' of the control inductor varies sinusoidally as a function of time around L2moy and with a pulse equal to 2 x ω2moy, so as to increase the amplitude of the electric current flowing in the receiver resonant circuit, growing exponentially.

As a variant, the inductance value L2f' of the control inductance varies so that the square of the proper pulsation ω2 varies sinusoidally as a function of time around (ω2avg)² and with a pulsation equal to 2 x ω2avg, from so as to increase the amplitude of the electric current flowing in the receiver resonant circuit, in exponential growth.

In other words, according to this last variant, the inductance value L2f' of the control inductance varies as a function of time according to 1/(C2' x (ω2)²), (ω2)² varying sinusoidally according to time and around the value (ω2moy)².

According to one implementation, the second capacitance has a substantially constant value.

According to one implementation, the receiver resonant circuit is arranged to carry out a power transmission of between 1 kW and 500 kW, in particular between 1 kW and 150 kW.

According to one implementation, the receiver resonant circuit is arranged to be tuned to the transmitter resonant circuit. Consequently, the receiver resonant circuit and the transmitter resonant circuit have substantially the same natural frequency.

According to one implementation, the predetermined frequency is equal to twice the natural frequency of the receiver resonant circuit to within a tolerance.

Such a predetermined frequency makes it possible to increase the amplitude of the electric current flowing in the receiver resonant circuit.

According to one implementation, the tolerance ε is such that ε = √(((1/2) x hL x ω2avg)² - (R2' / (L2'+L2f'))²).

Thus, the predetermined frequency is between (2xf2) - ε and (2xf2) + ε.

According to one implementation, the predetermined pulsation variation amplitude hω is strictly greater than 2 x (R2′ / (L2′+L2f′)) x √((L2′+L2f′) x C2′).

According to one implementation, the control inductor comprises a magnetic circuit.

According to one implementation, the control inductance is formed by a variable magnetic reluctance assembly comprising a rotor and a stator with the presence of an air gap between them,

• the stator comprising a solenoid and a plurality of stator arms, the set of stator arms forming a single magnetic pole when the solenoid is traversed by an electric current and the pole being considered in particular on the air gap side,
• the rotor comprising a plurality of rotor arms forming a single magnetic pole when the solenoid is traversed by an electric current and the pole being in particular considered on the air gap side.

According to one implementation, the solenoid comprises a flat turn, or a plurality of turns extending concentrically and/or extending axially, the turns being in particular devoid of Litz wire.

According to one implementation, the solenoid is arranged so that an alternating current flowing in the turns is strictly less than 3 kHz, for example between 40 Hz and 400 Hz.

According to one implementation, the turns comprise Litz wire whose section has a diameter strictly greater than 0.2 mm, in particular strictly greater than 0.3 mm.

This makes it possible to reduce the number of wires and therefore greatly simplify the implementation of the solenoid.

According to one implementation, the inductance value of the control inductor varies by variation of the reluctance of the magnetic circuit of the control inductor.

According to one implementation, the magnetic circuit of the control inductor comprises at least one moving part, relative to the second winding.

According to one implementation, the magnetic circuit of the control inductance comprises at least one fixed part, relative to the second winding.

According to one implementation, the fixed part and the mobile part comprise a ferromagnetic or ferrimagnetic material.

According to one implementation, the mobile part is set in motion so that the protrusions are alternately facing other protrusions or between two protrusions.

According to one implementation, the mobile part of the magnetic circuit of the control inductance is driven by an electric motor.

According to one implementation, the control inductance is made in a single piece.

According to one implementation, two adjacent rotor arms are separated two by two by a non-magnetic portion.

According to one implementation, two adjacent stator arms are separated two by two by a non-magnetic portion.

According to one implementation, the number of stator arms is equal to the number of rotor arms.

Alternatively, the number of stator arms is different from the number of rotor arms

According to one implementation, each stator arm extends in a direction radial with respect to the axis of rotation of the rotor and comprises a stack of laminated magnetic laminations, the stacking of which is in particular carried out in a direction orthoradial with respect to the direction radial in which extends the stator arm.

According to one implementation, the stack is made in a direction orthoradial with respect to the axis of rotation of the rotor.

As a variant, the stacking is carried out in a direction parallel to the axis of rotation of the rotor.

According to one implementation, each rotor arm extends in a direction radial with respect to the axis of rotation of the rotor and comprises a stack of laminated magnetic laminations, the stacking of which is in particular carried out in a direction orthoradial with respect to the direction radial in which extends the rotor arm.

According to one implementation, the stack is made in a direction orthoradial with respect to the axis of rotation of the rotor.

As a variant, the stacking is carried out in a direction parallel to the axis of rotation of the rotor.

According to one implementation, the rotor comprises an amagnetic shaft.

This allows the flow to pass only through the rotor arms and not through the shaft, in an axial direction.

According to one implementation, each rotor arm comprises a projecting portion, in particular arranged radially on the side of the axis of rotation of the rotor.

This allows good maintenance of the rotor arms on the shaft and limits the flow of leaks by channeling the magnetic flux from an external magnetic source.

According to one implementation, the rotor is coupled to a motor to allow it to be driven in rotation in particular at a predetermined speed Ω, this speed being expressed in revolutions/s and being such that Ω = ((2 x f2) ± ε / (N), N being the number of stator arms.

According to one implementation, the second capacitor comprises a polypropylene capacitor, in particular of at least 90 μF, for example of at least 900 μF.

The invention also relates to a contactless power transmission device by resonant inductive coupling, in particular for charging or recharging a motor vehicle with electrical energy, comprising:

• a source of energy, in particular alternating current,
• a resonant transmitter circuit comprising a first capacitance and a first winding, the first winding comprising a first inductor and a first resistor, the resonant transmitter circuit being powered by the energy source,
• a receiver resonant circuit as described above.

According to one implementation, the transmitter resonant circuit includes a variable inductance as described previously in the receiver resonant circuit.

Another subject of the invention is a contactless charging or recharging assembly for a motor vehicle, comprising:

• a contactless power transmission device by resonant inductive coupling as described previously,
• a rectifier, electrically connected to the receiver resonant circuit, to rectify an electric current generated by the variation of the magnetic field from the transmitter resonant circuit,
• an electrical energy storage device, charged by the rectifier.

The invention will be better understood on reading the following description and on examining the accompanying figures. These figures are given only by way of illustration but in no way limit the invention.

Figure 1 is a schematic representation of a contactless charging or recharging assembly of a motor vehicle according to the invention;

FIG. 2 is a schematic representation of a contactless power transmission device by resonant inductive coupling according to the invention;

Figure 3 is a schematic representation of a variable magnetic reluctance assembly according to the invention;

Figure 4 is a schematic representation of the assembly of Figure 3, according to section AA; And

FIG. 5 is a schematic representation of a control inductor according to the invention.

As visible in Figure 1, a motor vehicle 30 embeds an electrical energy storage device 20, in particular a battery 20 for supplying electrical energy to an electric traction motor, not shown, as well as the on-board network of the vehicle. motor vehicle 30. The battery 20 of the motor vehicle 30 has, for example, a nominal voltage of 48V or 300V and can be charged or recharged without contact using a contactless power transmission device by resonant inductive coupling 100.

In the example of FIG. 1, the contactless power transmission device by resonant inductive coupling 100 comprises an alternating current energy source 10 supplying a rectifier 12, the rectifier 12 being electrically connected to an inverter 13 which supplies thus a resonant circuit emitter 1 in alternating current according to a frequency higher than that of the source 10. Alternatively, the energy source 10 could be at a frequency that can be used directly without requiring the use of a rectifier 12 and an inverter 13 In the example of FIG. 1, it is the winding E0 which is supplied via the wired connection to the energy source 10. This winding E0 then supplies the resonant transmitter circuit 1 by inductive coupling.

In a variant not shown, the alternating current energy source 10 could directly supply the resonant transmitter circuit 1 with alternating current.

In the example of FIG. 1, the resonant transmitter circuit 1 comprises a first capacitance C1 and a first winding E1.

The contactless power transmission device by resonant inductive coupling 100 further comprises a resonant receiver circuit 2 comprising a second capacitance C2 and a second winding E2.

When the transmitter resonant circuit 1 is magnetically coupled to the receiver resonant circuit 2, there is contactless power transmission by resonant inductive coupling to the receiver resonant circuit 2. This magnetic coupling takes place when the first E1 and second E2 windings are in close proximity one of the other. In the example considered, this coupling takes place when the first E1 and second E2 windings are substantially at a distance of between 10 cm and 1 m. In another example, the coupling takes place, even if the performances are degraded, when the distance is between 1 m and 10 m.

As visible in Figure 2, the energy source 10 is connected to a resistor R0 in series with an emission coil L0. The winding E0 shown in Figure 1 indeed comprises the parasitic resistance R0 in series with an emission coil L0. In Figure 2, the rectifier 12 and the inverter 13 have not been shown for simplicity.

As visible in Figure 2, the resonant transmitter circuit 1 consists of an RLC circuit. Indeed, the resonant transmitter circuit 1 comprises a first inductor L1 in series with a first resistor R1 and a first capacitance C1. The first winding E1 represented in FIG. 1 indeed comprises the parasitic resistance R1 in series with the first inductor L1.

The transmit coil L0 is magnetically coupled to the first inductance L1.

The receiver resonant circuit 2 consists of an RLC circuit. Indeed, the receiver resonant circuit 2 comprises a second inductance L2 in series with a second resistor R2 and a second capacitance C2. The second winding E2 represented in FIG. 1 indeed comprises the parasitic resistance R2 in series with the second inductance L2.

The resonant receiver circuit 2 further comprises a control inductance L2f of value L2f' connected in series between the second resistor R2 and the second capacitance C2.

As a variant, the control inductance L2f is connected in series with an assembly comprising the second winding E2 and the second capacitance C2 in parallel.

This control inductance L2f is distinct from the second inductance L2.

The second capacitance C2 comprises a polypropylene capacitor, of at least 900 µF.

In the example shown, the transmitter resonant circuit 1 and the receiver resonant circuit 2 are tuned. The resonant receiver circuit 2 and the resonant transmitter circuit 1 thus have substantially the same natural frequency.

As visible in Figure 2, a receiving coil L3 is electrically connected to a resistor R3 schematically representing a parasitic resistance in series with the load constituted by the rectifier 11 and the battery 20 of Figure 1.

The winding E3 represented in figure 1 comprises here the parasitic resistance in series with the coil of reception L3.

Receiver coil L3 is magnetically coupled to second inductor L2.

In the example of Figures 1 and 2, the transmitter resonant circuit 1 and the transmitter coil L0 are located on the ground, while the receiver resonant circuit 2 and the receiver coil L3 are located on board the vehicle.

In the example of figures 1 and 2, the second capacitance has a value C2', the control inductance has a value L2f', and the second resistor has a value R2'. In addition, the receiver resonant circuit 2 has its own pulsation ω2 such that ω2=1/√((L2'+L2f') x C2') and its own frequency f2 such that f2 = ω2 / (2π).

The inductance value L2f' of the control inductor L2f varies in a predetermined manner.

More precisely, the inductance value of the control inductance L2f varies according to a predetermined frequency and according to a predetermined inductance variation amplitude hL around an average value L2moy, so that the proper pulsation varies according to an amplitude of variation of predetermined pulsation hω around a mean value ω2moy, with ω2moy = 1/√(L2moy×C2').

The predetermined frequency being chosen so as to increase the amplitude of the alternating electric current flowing in the resonant receiver circuit 2, in exponential growth.

The inductance value L2f' of the control inductance L2f varies sinusoidally as a function of time around L2moy and with a pulse equal to 2 x ω2moy, so as to increase the amplitude of the electric current flowing in the resonant receiver circuit 2, growing exponentially.

As a variant, the inductance value L2f' of the control inductance L2f varies so that the square of the proper pulsation ω2 varies sinusoidally as a function of time around (ω2moy)² and with a pulsation equal to 2 x ω2moy, so as to increase the amplitude of the electric current flowing in the resonant receiver circuit 2, increasing exponentially.

In other words, according to this variant, the inductance value L2f' of the control inductance varies as a function of time according to 1/(C2' x (ω2)²), (ω2)² varying sinusoidally as a function of the time and around the value (ω2avg)²

The second capacitance C2 has a substantially constant value. The term "substantially constant value" means the value of this capacitance, not including the variations thereof linked to temperature or wear or any other physical factor.

The predetermined frequency is equal to twice the natural frequency of the resonant receiver circuit 2 to within a tolerance ε. This tolerance ε is such that ε = (((1/2) x hL x ω2avg)² - (R2' / (L2'+L2f'))²).

Thus, the predetermined frequency is between (2xf2) - ε and (2xf2) + ε.

Such a predetermined frequency makes it possible to increase the amplitude of the electric current flowing in the receiver resonant circuit 2.

According to one implementation, the predetermined pulsation variation amplitude hω is strictly greater than 2 x (R2′ / (L2′+L2f′)) x √((L2′+L2f′) x C2′).

An example embodiment of the control inductance L2f is described in connection with figure 5.

The control inductance L2f is here formed an electronic voltage inverter 9.

The electronic voltage inverter 9 comprises power components, in particular IGBT type transistors forming at least two arms.

The electronic voltage inverter 9 delivers an AC voltage controlled by means of a DC control voltage VDC.

The DC control voltage VDC is ensured by a power supply capable of delivering a power greater than or equal to the power to be transmitted by the inductive resonant coupling.

The terminals from which the alternating voltage is delivered are the terminals forming the control inductance L2f, as emulated by the electronic voltage inverter 9.

Another embodiment of the control inductance L2f is described in connection with figures 3 and 4.

The control inductance L2f is here formed by a variable magnetic reluctance assembly comprising a rotor 6 and a stator 3 with the presence of an air gap between them. The stator 3 comprises a solenoid 5 and a plurality of stator arms 4, the set of stator arms 4 forming a single magnetic pole when the solenoid 5 is traversed by an electric current. The pole is here considered on the side of the air gap. The rotor 6 comprises a plurality of rotor arms 7 forming a single magnetic pole when the solenoid 5 is traversed by an electric current. The pole is here considered on the air gap side.

Thus, the solenoid 5 constitutes a winding. The stator constitutes a fixed part and the rotor constitutes a moving part, relative to the winding.

As can be seen in FIG. 3, two adjacent rotor arms 7 are separated in pairs by a non-magnetic portion and two adjacent stator arms 4 are separated in pairs by a non-magnetic portion. In the example considered, the number of stator arms 4 is equal to the number of rotor arms 7, in this case, this number is equal to 12.

Thus, the stator 3 has a plurality of protrusions, all of the same polarity, this polarity in the direction of the north or south orientation, being a function of the phase of the current passing through the solenoid 5. In addition, the rotor 6 has a plurality of saliences, all of the same polarity, this polarity in the direction of the north or south orientation, being a function of the phase of the current passing through the solenoid 5. The stator 3 and the rotor 6 each have the same number of magnetic saliences, separated by absence of magnetic material.

Each stator arm 4 extends in a direction radial with respect to the axis of rotation X of the rotor and comprises a stack of laminated magnetic laminations, the stacking of which is carried out in a direction orthoradial with respect to the radial direction in which extends the stator arm 4. In the example considered, the stack is made in a direction orthoradial with respect to the axis of rotation X of the rotor 6.

Each rotor arm 7 extends in a direction radial with respect to the axis of rotation X of the rotor and comprises a stack of laminated magnetic laminations, the stacking of which is carried out in a direction orthoradial with respect to the radial direction in which extends the rotor arm 7. In the example considered, the stack is made in a direction orthoradial with respect to the axis of rotation X of the rotor.

The rotor 6 comprises a shaft 8 which is made of a non-magnetic material. This allows the flow to pass only through the rotor arms 7 and not through the shaft 8, in an axial direction.

In the example considered, the non-magnetic shaft 8 of the rotor 6 is neither laminated nor made of soft ferrite in order to avoid the formation of harmful induced currents in said shaft 8.

As can be seen in Figure 4, each rotor arm 7 comprises a projecting portion, in particular arranged radially on the side of the axis of rotation X of the rotor 6. This allows the magnetic flux to be channeled while allowing better mechanical retention. of the assembly constituting the rotor 6.

In the example of Figure 3, the solenoid 5 comprises a plurality of turns extending concentrically. In the example of Figure 4, the solenoid 5 may comprise a plurality of turns extending axially. In a variant not shown, the solenoid 5 may comprise a single flat turn.

The whorls are devoid of Litz wire. As a variant, the turns comprise Litz wire whose section has a diameter strictly greater than 0.2 mm, in particular strictly greater than 0.3 mm.

The solenoid 5 is arranged so that an alternating current circulating in the turns composing it has a frequency strictly lower than 3 kHz.

An electric motor, not shown, is coupled to shaft 8 to allow rotor 6 to be driven in rotation at a predetermined speed Ω expressed in revolutions/s and being such that Ω = ((2xf0) ± ε / (N), N being the number of stator arms 4. This predetermined speed is considered in steady state, that is to say at the end of an electro-mechanical transient state.

Another embodiment of the control inductance L2f is as described in FIG. 3 and in the paragraphs, page 7 line 21 to page 8 line 14 of application FR 1853741 filed by the Applicant on April 24, 2018 with the INPI and which is incorporated by reference in this application.

Of course, the foregoing description has been given by way of example only and does not limit the scope of the invention, which would not be departed from by replacing the various elements with any other equivalents.

Further, the various features, variations, and/or embodiments of the present invention may be associated with each other in various combinations, so long as they are not mutually exclusive or mutually exclusive.

Claims (10)

Receiver resonant circuit (2) for carrying out contactless power transmission by resonant inductive coupling with a transmitter resonant circuit (1) comprising a first capacitance (C1) and a first winding (E1), the first winding (E1) comprising a first inductor (L1) and a first resistor (R1),

• the resonant receiver circuit (2) comprising a second capacitance (C2) of value C2' and a second winding (E2), the second winding (E2) comprising a second inductance (L2) of value L2', a second resistor (R2) of value R2', the resonant receiver circuit (2) further comprising a control inductance (L2f) of value L2f' connected in series with the second inductance (L2),
• the resonant receiver circuit (2) having a natural pulsation ω2 such that ω2=1/√ ((L2'+L2f') x C2') and a natural frequency f2 such that f2 = ω2/(2π),
• characterized in that the inductance value of the control inductor (L2f) varies in a predetermined manner.

Circuit (2) according to the preceding claim, the control inductance (L2f) being formed by an electronic voltage inverter (9), in particular arranged to emulate the electrical behavior of the control inductance (L2f) and the value of the 'L2f inductance'. Circuit (2) according to any one of the preceding claims, the inductance value L2f' of the control inductance (L2f) varying according to a predetermined frequency and according to a predetermined inductance variation amplitude hL around a value mean L2moy, so that the proper pulsation varies according to a predetermined pulsation variation amplitude hω around a mean value ω2moy, with ω2moy = 1/√((L2′+L2moy)×C2′). Circuit (2) according to Claim 3, the inductance value L2f' of the control inductance (L2f) varying sinusoidally as a function of time around L2moy and with a pulsation equal to 2 x ω2moy, so as to increase the amplitude of the electric current flowing in the resonant receiver circuit (2), increasing exponentially. Circuit (2) according to Claim 3, the inductance value L2f' of the control inductance (L2f) varying so that the square of the natural pulsation ω2 varies sinusoidally as a function of time around (ω2moy)² and with a pulse equal to 2 x ω2moy, so as to increase the amplitude of the electric current flowing in the resonant receiver circuit (2), increasing exponentially. Circuit (2) according to any one of the preceding claims, the resonant receiver circuit (2) being arranged to be tuned to the resonant transmitter circuit (1). Circuit (2) according to any one of Claims 2 to 6, characterized in that the predetermined frequency is equal to twice the natural frequency of the resonant receiver circuit (2) to within a tolerance ε. Circuit (2) according to the preceding claim, the tolerance ε being such that ε = √(((1/2) x hL x ω2avg)² - (R2'/(L2'+L2f'))²). Circuit (2) according to any one of Claims 2 to 8, the predetermined pulsation variation amplitude being strictly greater than 2 x (R2' / (L2'+L2f')) x √((L2+L2f') x C2'). Device (100) for contactless power transmission by resonant inductive coupling, in particular for charging or recharging a motor vehicle with electrical energy, comprising:

• an energy source (10), in particular alternating current,
• a resonant emitter circuit (1) comprising a first capacitance (C1) and a first winding (E1), the first winding (E1) comprising a first inductance (L1) and a first resistor (R1), the resonant emitter circuit (1) being powered by the energy source (10),
• a receiver resonant circuit (2) according to any one of the preceding claims.