receiver resonant circuit

Abstract

Receiver resonant circuit The invention relates to a receiver resonant circuit (2) for achieving contactless power transmission by resonant inductive coupling with a transmitter resonant circuit (1) comprising a first capacitance (C1) and a first winding, the first winding comprising a first inductance (L1) and a first resistance (R1), this receiver resonant circuit (2) comprising: - a second capacitance (C2) of value C2' and a second winding, the second winding comprising a second inductance (L2) of value L2' and a second resistance (R2) of value R2', - an inverter (24) emulating a variable inductance (L2v), which inductance has a variable value Lp and is in series with the second capacitance (C2), the variable inductance (L2v) being chosen so as to achieve a parametric amplification of the electric current in this receiver resonant circuit (2),- a rectifier (25) arranged to draw electrical current from the second winding (E2) to power the inverter. Figure of the abstract: Figure 3.

Description

Title of the invention: Resonant receiver circuit

[0001] The present invention relates to a resonant receiver circuit.

[0002] The present invention relates to a resonant receiver circuit and a device for contactless power transmission by inductive resonance coupling, in particular for charging or recharging a motor vehicle or any type of vehicle, land, air, or sea, propelled by means of electrical energy.

[0003] 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 25 kW, when this object is stationary (in this case we speak of a static load), or when it is moving (we then speak of a dynamic load). This supply by contactless transmission is then carried out by means of remote electrical circuits coupled magnetically and tuned to the same frequency. This frequency is the operating frequency of the circuit from the power source on the transmitter side, the primary, and the angular frequency or pulsation co being defined by co = 2.pi.f .

[0004] Magnetically coupled circuits each comprising at least one resonant LC element, L and C respectively designating inductances and capacitances.

[0005] A problem with this type of solution is that to transmit a satisfactory power level, 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.

[0006] Operating at such a high frequency level mainly results in the need to use, to make the coils, expensive components such as soft ferrites and Litz conductive wire whose strands are of small section, for example less than or equal to 0.07 mm in diameter.

[0007] The frequency and power levels mentioned above, for implementation in kWatts, may also constitute a danger to the health of people exposed nearby, or to the environment in general.

[0008] The present invention thus relates to a resonant receiver circuit for carrying out contactless power transmission by inductive resonance 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, this resonant receiver circuit comprising: - a second capacitance of value C2' and a second winding, the second winding comprising a second inductance of value L2' and a second resistor of value R2', - an inverter emulating a variable inductance, which inductance is of variable value Lp and in series with the second capacitance, the variable inductance being chosen so as to achieve a parametric amplification of the electric current in this resonant receiver circuit, - a rectifier arranged to draw electric current from the second winding to power the inverter.

[0009] According to the invention, the parametric current amplification, through the appropriate control of the variable inductance, is carried out exclusively in the secondary circuit or receiver circuit.

[0010] The variable inductor operates in the manner of a pump in which pump energy is supplied by the rectifier to the inverter.

[0011] The controlled variation of the inductance achieves a type of energy transfer on the exploitation of a non-linearity, with an induced negative resistance effect.

[0012] The invention makes it possible, due to the parametric amplification, to obtain a satisfactory efficiency between the primary circuit (transmitter) and the secondary circuit (receiver) although the circuit operates at relatively low frequencies. This frequency may be less than 10 kHz, for example less than 1 kHz, the frequency being in particular substantially equal to 400 Hz, as for example in on-board aeronautical electrotechnical applications, which do not constitute a danger to the health of people exposed nearby, unlike radiofrequency bands such as 85 kHz or 100 kHz, for power levels exceeding several kW.

[0013] The useful power delivered by the receiver circuit to a load can be of the order of several kWatts. For example, the invention makes it possible to deliver a power of approximately 2.5 kWatts for 230 Volts effective at 400 Hz.

[0014] The efficiency, namely the ratio between the power delivered at the output by the secondary circuit and the power at the input in the primary circuit, is greater than 60%, in particular greater than or equal to 75% or even 90%.

[0015] According to one aspect of the invention, the ratio i2eff / ileff of the received effective current i2eff to the transmitted effective current ileff is greater than 0.75, or even greater than 0.90 at low frequency, for example at a frequency of 400 Hz.

[0016] The invention thus makes it possible to transfer electrical power of up to several kWatts, for example a power greater than 1 kWatt or 5 kWatts, while remaining at relatively low frequencies which do not present any substantial danger to the health of people nearby.

[0017] According to one aspect of the invention, the output of the rectifier is connected to the input of the inverter.

[0018] According to one aspect of the invention, a filter, in particular an RC type filter, is connected to the rectifier output terminals and the inverter input terminals.

[0019] The role of this filter is in particular to avoid a short circuit.

[0020] According to one aspect of the invention, the inductance value Lp of the variable inductance (L2v) can be controlled by the inverter to vary according to the law Lp(t) = L0.(l+h.cos(2co0 .t+q>)) with t the time, L0 a fixed inductance value preferably lower than the value L2' of the inductance (L2), h a parametric amplification parameter, coO the natural pulsation of the circuits (L1,C1) and (L2,C2) with Ll'.Cl'.coO2 = L2'.C2'.co02= 1, and cp the phase which can be chosen to be zero or non-zero.

[0021] The phase cp is a value fixed in advance.

[0022] It should be noted that the addition of L2v causes us to move away from the impedance compensation condition, and the angular frequency or natural pulsation coO is valid for (L2,C2) and not for (L2+L2v,C2).

[0023] Alternatively, the inductance value Lp of the variable inductance (L2v) can be controlled by the inverter to vary according to the law Lp(t) = L0 / (l+h.cos(2co0.t)) with t the time, L0 a fixed inductance value preferably lower than the value L2' of the inductance (L2), h a parametric amplification parameter strictly lower than 1, and coO the natural pulsation of the circuits (L1,C1) and (L2,C2) with Ll'.Cl'.coO2 = L2'.C2'. co02= 1.

[0024] In another variant of the invention, the inductance value Lp of the variable inductance (L2v) can be controlled by the inverter to vary according to the law Lp(t) = L0.(l / (l+h.cos(2co0.t)) - k2) with t the time, L0 is a chosen output inductance value that LO.C.coO2 = 1, h a parametric amplification parameter strictly less than 1, coO the natural pulsation of the receiver circuit, and k2 a constant chosen between 0 and 1.

[0025] According to one aspect of the invention, the parameter h is chosen to be strictly less than 1, in particular h=0.3 or h=0.5 or h=0.7 or h=0.9.

[0026] This value h is fixed in advance, and does not vary during the operating cycles of the circuit.

[0027] According to one aspect of the invention, the variable inductance is controlled to vary at a frequency twice the natural frequency of the receiver circuit.

[0028] According to one aspect of the invention, the receiver circuit comprises a load resistor (Rc) through which the supply of useful electrical power is produced, delivered for example to an electrical energy storage device such as a battery.

[0029] According to one aspect of the invention, the inverter comprises power components, for example IGBT type transistors forming at least two arms.

[0030] According to one aspect of the invention, the distance d between the inductances L1 and L2 is between 10 and 30 cm, being substantially equal to 18 cm or 20 cm.

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[0046] The inductance value of L1 is also denoted Ll'. The inductance value of L2 is L2'. The capacitance value of Cl is denoted Cl'. According to one aspect of the invention, the receiver resonant circuit is arranged to be tuned to the transmitter resonant circuit. As a result, the receiver resonant circuit and the transmitter resonant circuit have substantially the same natural frequency. According to one aspect of the invention, the inductor L2 comprises a coil of 3 to 7 layers of turns. According to one aspect of the invention, the inductance L2 comprises a coil of turns formed from sheathed copper wires, for example with a cross-section of 6 mm2. The coils of the primary and secondary circuit windings are all made of copper wire. So these coils are free from Litz wires, which are expensive. The invention also relates to a device for contactless power transmission by inductive resonance coupling, in particular for charging or recharging a vehicle with electrical energy, comprising: - a source of energy, in particular alternating current, - a resonant emitter circuit comprising a first capacitance and a first winding, the first winding comprising a first inductance and a first resistance, the resonant emitter circuit being powered by the energy source, - a resonant receiver circuit as described above. Other characteristics, details and advantages of the invention will emerge more clearly on reading the detailed description given below, and several examples of embodiment given for informational and non-limiting purposes with reference to the attached schematic drawings, in which: [Fig.l] is a schematic representation of a contactless charging or recharging assembly for a motor vehicle according to the invention, [Fig.2] is a schematic representation of a contactless power transmission device by inductive resonance coupling according to the invention, [Fig.3] schematically and partially represents the receiver circuit of the device of [Fig.2], [Fig.4] illustrates the parametric amplification of the current obtained in the receiver circuit of [Fig.3], [Fig.5] illustrates the variations of the inductance for different values ​​of h, according to a first control law, used in the receiver circuit of [Fig.3], [Fig.6] illustrates the derivative of the inductance curves of the curves of [Fig.5], [Fig.7] illustrates the variations of the inductance for different values ​​of h, according to a second control law, used in the receiver circuit of [Fig.3],

[0047] [Fig.8] illustrates the derivative of the inductance curves of the curves of [Fig.5].

[0048] [Fig. 1] shows a motor vehicle 30 which has an electrical energy storage device 20 on board, in particular a battery 20 for supplying electrical energy to an electric traction motor (not shown) and the on-board network of the 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 thus supplies a resonant transmitter circuit 1 with alternating current at a frequency higher than that of the source 10.Alternatively, the power source 10 could be at a frequency that can be used directly without requiring the use of a rectifier 12 and an inverter 13.

[0049] In the example of [Fig.l], it is the winding E0 which is powered via the wired connection to the energy source 10. This winding E0 then powers the resonant emitter circuit 1 by inductive coupling. In a variant not shown, the alternating current energy source 10 could directly power the resonant emitter circuit 1 with alternating current.

[0050] In the example of [Fig.l], the resonant transmitter circuit 1, or also called primary circuit, comprises a first capacitance C1 and a first winding E1. The contactless power transmission device by inductive resonance coupling 100 further comprises a resonant receiver circuit 2, or also called secondary circuit, comprising a second capacitance C2 and a second winding E2.

[0051] When the transmitter resonant circuit 1 is magnetically coupled to the receiver resonant circuit 2, there is contactless power transmission by inductive resonant coupling to the receiver resonant circuit 2.

[0052] This magnetic coupling takes place when the first E1 and second E2 windings are close to each other.

[0053] 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.

[0054] In another example, coupling takes place, even if performance is degraded, when the distance is between 1 m and 10 m.

[0055] As seen in [Fig.2], the energy source 10 is connected to a resistor R0 in series with a transmission coil L0. The winding E0 shown in [Fig.l] in fact comprises the parasitic resistor R0 in series with a transmission coil L0.

[0056] In [Fig.2], the rectifier 12 and the inverter 13 have not been shown for more than simplicity.

[0057] As visible in [Fig.2], the resonant emitter circuit 1 is formed of a circuit RLC. In fact, the resonant emitter circuit 1 comprises a first inductance L1 in series with a first resistance RI and a first capacitance Cl. The first winding El shown in [Fig.l] in fact comprises the parasitic resistance RI in series with the first inductance Ll.

[0058] The transmission coil LO is magnetically coupled to the first inductance LL

[0059] 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.

[0060] The second winding E2 shown in [Fig.l] in fact includes the parasitic resistance R2 in series with the second inductance L2.

[0061] The resonant transmitter circuit 1 and the resonant receiver circuit 2 are tuned. The resonant receiver circuit 2 and the resonant transmitter circuit 1 thus have substantially the same natural frequency.

[0062] The inductance values ​​of L1 and L2 are chosen to be less than 50 mH (millihenry).

[0063] As seen in [Fig.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 [Fig.l]. The winding E3 shown in [Fig.l] here comprises the parasitic resistance in series with the receiving coil L3. The receiving coil L3 is magnetically coupled to the second inductance L2. In the example of Figures 1 and 2, the transmitter resonant circuit 1 and the transmitting coil L0 are located on the ground, while the receiver resonant circuit 2 and the receiving coil L3 are located on board the vehicle.

[0064] As illustrated in [Fig.3] relating to an example of implementation of the variable inductance, the resonant receiver circuit 2 comprises: - in addition to the second capacitance C2 of value C2' and the second winding E2, the second winding E2 comprising the second inductance L2 of value L2' and a second resistance R2 of value R2', - an inverter 24 emulating a variable inductance L2v, which inductance is of variable value Lp and in series with the second capacitance C2 and the resistor R2, the variable inductance L2v being chosen so as to achieve a parametric amplification of the electric current in this resonant receiver circuit 2, - a rectifier 25 arranged to draw electric current from the second winding E2 to power the inverter 24.

[0065] The natural pulsation of this circuit is coO=l / 'V((L2'+Lp) x C2').

[0066] The output of the rectifier 25 is connected to the input of the inverter 25.

[0067] A filter 27, in particular an RC type filter, is connected to the output terminals 28 of the rectifier 25 and to the input terminals 29 of the inverter 24.

[0068] The role of this filter 27 is in particular to avoid a short circuit.

[0069] The receiver circuit 2 comprises a load resistor 31 of value Rc, through which the supply of useful electrical power delivered to the electrical energy storage device such as a battery 20 occurs.

[0070] This load resistor 31 symbolically materializes in [Fig.3] the supply of useful power to the load. For simplicity, this load resistor is not shown in [Fig.2].

[0071] The value Rc is, in the example described, 50 Ohms.

[0072] Thus, for an effective current in the secondary circuit 2, or receiver circuit, which has an intensity of several Amperes, for example an intensity of between 5 and 15 Amperes, for example substantially 7 Amperes, it is possible to draw a useful power of several kWatts, for example at least 2 or 3 kWatts, for a frequency of 400 Hz.

[0073] For example, the useful power delivered by the receiver circuit to a load can be of the order of several kWatts. For example, the invention makes it possible to deliver a power of approximately 2.5 kWatts for 230 Volts effective at 400 Hz.

[0074] For comparison, the values ​​of RI and R2 are notably less than 1 Ohm.

[0075] In one example, the dimensions of the primary coil, in particular on the charging terminal, and the secondary coil on the vehicle are given below.

[0076] The outer diameter Dext is chosen to be 50 cm, the inner diameter Dint to be 25 cm, with 7 layers of turns and 27 turns per layer.

[0077] 6 mm2 solid copper wires are used. No Litz wire is used.

[0078] The operating frequency is 410 Hz, which results in a pumping frequency, at the variable inductance, of 820 Hz.

[0079] It is chosen: - At primary, Cl = 6.8 pF, LI = 22.1 mH, RI = 0.76 Ohm - On the secondary, C2 = 6.8 pF, L2 = 22.1 mH, R2 = 0.76 Ohm

[0080] The distance between primary and secondary is chosen at 20 cm.

[0081] The mutual inductance is 3.3 mH, and the coupling k = 0.15.

[0082] A resonance operation is chosen which offers the best compensation, with co = co0, with classically LC co0 2 = 1.

[0083] In the example described, the inductance value Lp of the variable inductance (L2v) can be controlled by the inverter to vary according to the law Lp(t) = L0 / (l+h.cos(2co0.t)) with t the time, L0 a fixed inductance value preferably lower than the value L2' of the inductance (L2), h a parametric amplification parameter strictly lower than 1, and coO the natural pulsation of the circuits L1,C1 and L2,C2 with Ll'.Cl'. coO2 = L2'.C2'. co02= 1.

[0084] The phase q> is a value fixed in advance.

[0085] The parameter h is chosen to be strictly less than 1, in particular h=0.3 or h=0.5 or h=0.7 or 11=0.9.

[0086] This value h is fixed in advance, and does not vary during the operating cycles of the circuit.

[0087] [Fig.5] shows the variation curves of the variable inductance Lp(t) as a function of time (normalized by a predetermined constant value L0), for h=0.3 (curve 5a) or h=0.5 (curve 5b) or h=0.7 (curve 5c) or h=0.9 (curve 5d).

[0088] [Fig.5] also shows the variation curve 5e of the electric current i(t) (divided by a constant value iO). The current does not depend on the quantity h.

[0089] It is constant that the inductance varies at a frequency twice the frequency of the current.

[0090] [Fig.6] shows the variation curves of the derivatives of the inductances of [Fig.5] for the four values ​​of h mentioned above, corresponding respectively to curves 6a, 6b, 6c and 6d of [Fig.6].

[0091] The current i(t) is squared (curve 6e) on this [Fig.6].

[0092] The curves in [Fig.6] allow us to visualize the energy aspect, namely the pump energy on the variable inductance.

[0093] [Fig.4] shows the current in the primary circuit (transmitter circuit) and the current in the secondary circuit (receiver circuit).

[0094] We see the effect of the parametric amplification on the curve CI2 associated with the current in the receiver circuit 2 which increases along a concave envelope, notably in an exponential manner, while the current (curve Cil) in the transmitter circuit 1 increases along a convex envelope.

[0095] The increase in current in the receiver circuit 2 is in practice limited to a saturation threshold, preventing any runaway.

[0096] It should be noted that the curves in [Fig.4] are given solely as an illustration of the dynamic behavior in parametric amplification, and the values ​​on the ordinate in this [Fig.4] are only an example that can be used.

[0097] Alternatively, with reference to figures 7 and 8, the inductance value Lp of the variable inductance L2v can be controlled by the inverter to vary according to the law Lp(t) = L0.(l+h.cos(2co0 .t+q>)) with t the time, L0 a fixed inductance value preferably lower than the value L2' of the inductance (L2), h a parametric amplification parameter, coO the natural pulsation of the circuits L1,C1 and L2,C2 with Ll'.Cl'. coO2 = L2'.C2'. co02= 1, and q> the phase which can be chosen to be zero or non-zero.

[0098] The phase q> is a value fixed in advance.

[0099] The parameter h is chosen to be strictly less than 1, in particular h=0.3 or h=0.5 or h=0.7 or h=0.9.

[0100] This value h is fixed in advance, and does not vary during the operating cycles of the circuit.

[0101] [Fig.7] shows the variation curves of the variable inductance Lp(t) as a function of time (normalized by a predetermined constant value L0), for h=0.3 (curve 7a) or h=0.5 (curve 7b) or h=0.7 (curve 7c) or h=0.9 (curve 7d).

[0102] [Fig.7] also shows the variation curve 7e of the electric current i(t) (divided by a constant value iO).

[0103] The current does not depend on the quantity h.

[0104] It is constant that the inductance varies at a frequency twice the frequency of the current.

[0105] [Fig.8] shows the variation curves of the derivatives of the inductances of [Fig.7] for the four values ​​of h mentioned above, corresponding respectively to curves 8a, 8b, 8c and 8d of [Fig.7].

[0106] The current i(t) is squared (curve 8e) on this [Fig.8].

[0107] The curves in [Fig.8] allow us to visualize the energy aspect, namely the pump energy on the variable inductance.

[0108] The inverter 24 comprises power components, for example IGBT type transistors forming at least two arms.

[0109] In the example described, the distance d, visible in [Fig.3], between the inductances L1 and L2 is between 10 and 30 cm, being substantially equal to 18 cm or 20 cm.

[0110] The receiver resonant circuit 2 is arranged to be tuned to the transmitter resonant circuit 1.

[0111] Consequently, the receiver resonant circuit 2 and the transmitter resonant circuit 1 have substantially the same natural frequency.

[0112] The inductance L2 comprises a coil of 3 to 7 layers of turns.

[0113] Other numbers of layers of turns can of course be chosen.

[0114] The inductance L2 comprises a coil of turns formed from sheathed copper wires, for example with a cross-section of 6 mm2.

[0115] The coils of the primary and secondary circuit windings are all made of copper wires, without Litz wires, which are expensive.

[0116] The invention makes it possible, due to the parametric amplification, to obtain a satisfactory efficiency between the primary circuit (transmitter) and the secondary circuit (receiver) although the circuit operates at 400 Hz.

[0117] The efficiency, namely the ratio between the power delivered at the output by the secondary circuit and the power at the input in the primary circuit, is greater than 60%, in particular greater than or equal to 75% or even 90%.

[0118] Of course, the invention is not limited to the implementation examples described above.

[0119] For example, in another embodiment of the invention, the inductance value Lp of the variable inductance L2v can be controlled by the inverter to vary according to the law Lp(t) = L0.(l / (l+h.cos(2co0.t)) - k2) with t the time, LO is a chosen output inductance value that LO.C. coO2 = 1, h a parametric amplification parameter strictly less than 1, coO the natural pulsation of the receiver circuit, and k2 a constant chosen between 0 and 1.

[0120] In this exemplary embodiment of the invention, the aim is to reduce the value L2' of the inductance L2 which is chosen to be lower than L0.

[0121] In this embodiment, we can set a critical value of h noted hc, with hc = 2.R / (L. coO). The value L is that of L0 so that LO.C. coO2 = 1. The instability, which is sought, is ensured if the parameter h is chosen between 0 and 1 and greater than hc.

[0122] Thus for R = R2 + Rc = 0.76 + 17 Ohm (namely R2= 0.76 Ohm and Rc= 17 Ohm), then hc < 1.

[0123] The variable inductance Lp(t) cannot be negative, which gives k2 < l / (l+h.cos(2cot)), with min[l / (l+h.cos(2co0.t))] which tends towards 0.5, when h tends towards 1.

[0124] We thus obtain examples of combinations (h, k2) of interest: h = 0.3 , min[l / (l+h.cos(2 coO.t))] = 0.769, hence k2 = 0.76, for slower dynamics, h = 0.9 , min[l / (l+h.cos(2 coO.t))] = 0.526, hence k2 = 0.52, for faster dynamics, h = 0.7 (prox. 0.57), min[l / (l+h.cos(2 coO.t))] = 0.588, hence k2 = 0.57.

Claims

Claims

1. Resonant receiver circuit (2) for carrying out contactless power transmission by resonant inductive coupling with a resonant transmitter circuit (1) comprising a first capacitance (Cl) and a first winding (El), the first winding (El) comprising a first inductance (Ll) and a first resistance (RI), this 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' and a second resistance (R2) of value R2', - an inverter (24) emulating a variable inductance (L2v), which inductance is of variable value Lp and in series with the second capacitance (C2), the variable inductance (L2v) being chosen so as to carry out a parametric amplification of the electric current in this resonant receiver circuit (2),- a rectifier (25) arranged to draw electric current from the second winding (E2) to power the inverter.,

2. A resonant receiver circuit according to the preceding claim, wherein the output of the rectifier (25) is connected to the input of the inverter.

3. Resonant receiver circuit according to the preceding claim, in which a filter (27), in particular an RC type filter, is connected to the output terminals of the rectifier and to the input terminals of the inverter.

4. Resonant receiver circuit according to one of the preceding claims, in which the inductance value Lp of the variable inductance (L2v) can be controlled by the inverter to vary according to the law Lp(t) = L0.(l+h.cos(2co0 .t+q>)) with t the time, LO a fixed inductance value preferably lower than the value L2' of the inductance (L2), h a parametric amplification parameter, coO the natural pulsation of the circuits L1,C1 and L2,C2 with Ll'.Cl'. coO2 = L2'.C2'. co02= 1, and q> the phase which can be chosen to be zero or non-zero.

5. Resonant receiver circuit according to one of claims 1 to 3, in which the inductance value Lp of the variable inductance (L2v) can be controlled by the inverter to vary according to the law Lp(t) = L0 / (l+h.cos(2co0.t)) with t the time, LO a fixed inductance value preferably less than the value L2' of the inductance (L2), h a parametric amplification parameter strictly less than 1, and coO the natural pulsation of the circuits L1,C1 and L2,C2 with Ll'.Cl'. coO2 = L2'.C2'.co02= 1.

6. Resonant receiver circuit according to one of claims 1 to 3, in which the inductance value Lp of the variable inductance (L2v) can be controlled by the inverter to vary according to the law Lp(t) = L0.(l / (l+h.cos(2co0.t)) - k2) with t the time, LO is a chosen output inductance value that LO.C. coO2 = 1, h a parametric amplification parameter strictly less than 1, coO the natural pulsation of the receiver circuit, and k2 a constant chosen between 0 and 1.

7. Resonant receiver circuit according to one of the preceding claims, in which the parameter h is chosen to be strictly less than 1, in particular h=0.3 or h=0.5 or h=0.7 or h=0.

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8. Resonant receiver circuit according to the preceding claim, in which this value h is fixed in advance.

9. Resonant receiver circuit according to one of the preceding claims, in which the variable inductance (L2v) is controlled to vary at a frequency twice the natural frequency of the receiver circuit (2).

10. Resonant receiver circuit according to one of the preceding claims, comprising a load resistor (Rc) through which the supply of useful electrical power is produced, delivered for example to an electrical energy storage device such as a battery.

11. Resonant receiver circuit according to one of the preceding claims, in which the inverter (24) comprises power components, for example IGBT type transistors forming at least two arms.

12. Resonant receiver circuit according to one of the preceding claims, in which the distance d between the inductances (L1) and (L2) is between 10 and 30 cm, being substantially equal to 18 cm or 20 cm.

13. A resonant receiver circuit according to any preceding claim, wherein the resonant receiver circuit is arranged to be tuned to the resonant transmitter circuit.

14. Resonant receiver circuit according to one of the preceding claims, in which the inductance L2 comprises a coil of 3 to 7 layers of turns.

15. A resonant receiver circuit according to any preceding claim, wherein the inductor L2 comprises a coil of turns formed from copper wires.

16. Device (100) for contactless power transmission by inductive resonance coupling, in particular for charging or recharging a vehicle with electrical energy, comprising: - an energy source (10), in particular alternating current, - a resonant emitter circuit (1) comprising a first capacitance (Cl) and a first winding (El), the first winding (El) comprising a first inductance (Ll) and a first resistance (RI), the resonant emitter circuit (1) being powered by the energy source (10), - a resonant receiver circuit (2) according to any one of the preceding claims.

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