Method and apparatus for transferring electrical power

Abstract

A method and an apparatus for transferring electric power to an electrical load (105); the method includes steps of: converting a direct electric current into an electric tension wave, applying the electric tension wave in inlet to at least a couple of electric capacitors (125, 130); supplying the electrical load (105) with the electric tension in outlet from the capacitors (125, 130).

Claims

1. A method for transferring electric power to an electrical load (105), comprising steps of: converting an direct electric current into an electric tension wave, applying the electric tension wave in inlet to at least a couple of electric capacitors (125, 130) including a first electric capacitor (125) and a second electric capacitor (130), supplying the electrical load (105) with the electric tension in outlet from the capacitors (125, 130), wherein the conversion step comprises: alternatingly switching a single active switch (155) on and off, and lowering electrical power dissipated by the active switch (155) to a substantially nil value during each transition step of the active switch (155).

2. The method of claim 1, comprising a further step of: rectifying the electric tension wave in outlet from the first and second electric capacitors (125,130).

3. The method of claim 1, comprising steps of: preventing one or more switching on and off cycles of the active switch (155).

4. The method of claim 3, wherein a regulating of the electrical power transferred is performed with a feedback control which comprises the steps of: measuring the electrical power transferred to the electrical load, calculating the difference between the electrical power measured and the predetermined reference value, and regulating the number and/or the frequency of the switching on and off cycles inhibited, such as to minimize the difference.

5. The method of claim 1, comprising a deviation step of: temporarily deviating the electric tension wave onto an electrical line in parallel to the electrical load (105), wherein the electric line comprises a second active switch (190) and a third capacitor (185) connected in series with the second active switch and having a capacitor value that is sufficiently high to be considered a short-circuit with respect to the electrical load, when the second active switch is switched on.

6. The method of claim 5, wherein a regulating of the electrical power transferred is performed with a feedback control comprising the steps of: measuring the electrical power transferred to the electrical load, calculating the difference between the measured electrical power and the predetermined reference value, and regulating the duration of the deviation step and/or the frequency with which the deviation step is eventually repeated, such as to minimize the difference.

7. The method of claim 1, comprising a step of: regulating the direct electric current.

8. The method of claim 1, wherein the direct electric current is obtained via a step of rectifying an alternating electric current.

9. The method of claim 1, wherein the first armature (325) of each of the first and second electric capacitors (125, 130) is installed on a user device (305), while the second armature (320) of each of the first and second electric capacitors (125, 130) is installed on a supply device (300) separate and independent of the user device (305), and wherein the method comprises nearing the user device (305) to the supply device (300) such that the first armature (325) installed on the user device (305) and the second armature (320) installed in the supply device (300) realize the first and second electric capacitors (125, 130).

10. An apparatus (100) for transferring electric power to an electrical load (105), comprising: at least a pair of electric capacitors (125, 130) including a first electric capacitor (125) and a second electric capacitor (130), converter means (135) for converting a direct electric tension into an electric tension wave, means for applying the electric tension wave in inlet to the capacitors (125, 130), means for supplying the electrical load (105) with the electric tension in outlet from the pair of electric capacitors, wherein the converter means (135) comprise a switching circuit comprising: a single active switch (155), means (160) for generating an electrical pilot signal suitable for switching the active switch (155) on and off, and a reactive circuit (145) set up such as to lower electrical power dissipated by the active switch (155) to a substantially nil value, during each transition step of the active switch (155).

11. The apparatus of claim 10, comprising: means (140) for rectifying the electric tension wave in outlet from the capacitors (125, 130).

12. An apparatus (100) according to claim 10, wherein the converter means (135) comprise: a first inductor (150) connected in series with a DC tension source (110) and with the active switch (155), said active switch (155) having a first end connected with the output terminal of the first inductor (150), and a second end connected in short circuit with the DC tension source (110), and a piloting head connected with a driver (160), a third capacitor (165) connected in series with the first inductor (150) and in parallel with the active switch (155), the output terminal of said further capacitor (165) being connected in short circuit with the DC tension source (110), via an electrical branch to which the active switch (155) and the second isolation capacitor (130) are also connected.

13. The apparatus (100) of claim 12, wherein the converter means (135) comprise a second inductor (170) connected in series with both the first inductor (150) and the first isolation capacitor (125), and connected in parallel with both the active switch (155) and the third capacitor (165).

14. The apparatus (100) of claim 10, wherein the reactive circuit (145) is configured as a passband filter for the electric tension wave, and is set up so as to pass one or more of the fundamental frequencies of the electric tension wave chosen among the group constituted by: the first fundamental frequency of the electric tension wave, the third fundamental frequency of the electric tension, or other odd harmonics of a higher order.

15. The apparatus (100) of claim 10, comprising control means (160) for controlling the electrical pilot signal, the control means being configured for: suspending the generating of the electrical pilot signal, such as to prevent one or more consecutive switching on and off cycles of the active switch (155).

16. The apparatus of claim 15, wherein the control means are configured such as: measuring, using appropriate sensors, an electric parameter characteristic of the electric power transferred to the electrical load (105), calculating the difference between the measurement of the electrical parameter characteristic of the electric power and the predetermined reference value, and regulating the number and/or the frequency of switching-on and off cycles which are inhibited, such as to minimize the difference.

17. The apparatus (100) of claim 10, comprising: means (185, 190) for temporarily deviating the electric tension wave onto an electrical line in parallel to the electrical load (105) wherein the means for deviating the electric tension wave comprise a second active switch (190), a third electric capacitor (185) arranged in series to the second active switch (190) along the electric line, and means for generating an electrical pilot signal for switching on and off the second active switch (190) alternatingly, the third electric capacitor (185) having a sufficiently high value to be considered as a short circuit with respect to the electrical load (105), when the second active switch is on.

18. The apparatus of claim 17, comprising a control circuit configured for: measuring an electric parameter characteristic of the electric power transferred to the electrical load (105), calculating the difference between the measurement of the electric parameter characteristic of the electric power and the predetermined reference value, and regulating the duty-cycle of the electric pilot signal of the second active switch, such as to minimize the difference.

19. The apparatus (100) of claim 10, comprising: means (200) for regulating the direct electric tension.

20. The apparatus (100) of claim 10, comprising: means (111) for rectifying an alternating electrical current in order to obtain the direct electric tension.

21. The apparatus (100) of claim 10, wherein each of the capacitors (125, 130) is a pre-assembled component, and wherein the capacitors (125, 130) are installed in a same device (250).

22. The apparatus (100) of claim 10, comprising a user device (305) and a supply device (300) separate and independent of the user device (305), wherein the user device (305) comprises a first armature (320) of each of the capacitors (125, 130), while the supply device (300) comprises the second armature (320) of each of the capacitors (125, 130).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further characteristics and advantages of the invention will emerge from a reading of the following description, provided by way of non-limiting example, with the aid of the figures illustrated in the accompanying tables of drawings.

(2) FIG. 1 is a simplified circuit diagram of an apparatus for transferring electric power according to an embodiment of the present invention.

(3) FIG. 2 is a variant of the simplified circuit diagram of FIG. 1.

(4) FIG. 3 is a more detailed circuit diagram of the apparatus of FIG. 1.

(5) FIG. 4 is a variant of the circuit diagram of FIG. 3.

(6) FIG. 5 is a variant of the circuit diagram of FIG. 4.

(7) FIG. 6 schematically illustrates a practical realisation of the apparatus of FIG. 1.

(8) FIG. 7 is a schematic diagram of a second practical embodiment of the apparatus of FIG. 1.

(9) FIG. 8 is the detail VIII of FIG. 7, in enlarged scale.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(10) As shown in FIG. 1, an embodiment of the present invention provides an apparatus 100 for transferring electrical power to an electrical charging device 105.

(11) The electrical charging device 105 may be for example any electric or electronic device that must be powered to enable operation and/or to charge the internal batteries of the device itself. Classic examples of this type of electrical/electronic device are mobile phones, computers, televisions and others besides.

(12) From a circuit point of view, the apparatus 100 shown in the example of FIG. 1 is a DC/DC converter, which is suitable for transferring electric power from a DC tension source 110 to a charging device 105, which is here generally denoted by an electrical resistance symbol.

(13) The DC tension source 110 may be for example a battery.

(14) Alternatively, the source 110 could include a rectifier 111, for example, a diode bridge, a single diode, a coupled double diode, or another synchronous rectifier, which is suitable for connecting with a source of alternating tension 112, for example a common electrical distribution grid at 230V and 50 Hz, so as to rectify the alternating tension generated by the source 112. A filter stabilizer may be present immediately downstream of the rectifier 111. In the second case, the apparatus 100 would be more properly configured as an AC/DC converter.

(15) The apparatus 100 schematically comprises a primary circuit 115 directly connected with the source 110, and a secondary circuit 120 directly connected with the charging device 105, which are mutually electrically isolated by at least a pair of isolating electric capacitors, of which a first capacitor 125 and a second capacitor 130.

(16) The primary circuit 115 comprises a converter 135 for converting the direct electric tension generated by the source 110 into a tension wave, i.e. into a succession of tension pulses in which each tension pulse varies from a minimum value, for example but not necessarily substantially nil, to a maximum value depending on the entity of the DC tension at input.

(17) The tension wave in output from the converter 135 is then applied to the pair of capacitors 125 and 130, which transmit the tension wave to the secondary circuit 120.

(18) The secondary circuit 120 includes a rectifier 140, which is suitable for rectifying the tension wave in output from the pair of capacitors, so as to newly obtain a DC tension. The rectifier 140 may be a bridge diode rectifier, a single diode, a coupled double diode, or another synchronous rectifier. Possibly, the rectifier 140 may be combined with a subsequent stabilization stage of the tension (e.g. LC filter or other).

(19) The direct tension output from the rectifier 140 is then applied to the input terminals of the electrical charging device 105 to be supplied.

(20) In practice, the electrical charging device 105 is connected in series between the two capacitors 125 and 130 which, as they can be regarded as a pair of impedances, enable transmission to the secondary circuit 120 of a sufficiently high tension wave to be rectified in the rectifier 140, possibly stabilized, and then used to supply the charging device 105.

(21) Note at this point that in other embodiments the rectifier 140 may be absent, thus obtaining a DC/AC (or AC/AC) converter capable of supplying the charging device 105 with an alternating tension.

(22) Entering into more detail, in a preferred aspect of the invention the converter 135 includes a switching circuit 142, which is suitable for generating the tension wave applied to the capacitors 125 and 130.

(23) In general, the switching circuit 142 comprises at least one active switch 155, for example a transistor (e.g. BJT bipolar junction transistor, FET field effect transistor, MOSFET, MESFET, JFET, IGBT and others besides), and a driver for applying an electrical pilot signal to the active switch 155, which signal can turn on (i.e. in saturation) and off (inhibit) the active switch.

(24) Here it is specified that although in the present example the switching circuit 142 is located upstream of the galvanic isolation capacitors 125 and 130, in other embodiments the same switching circuit 142 could be placed between the galvanic isolation capacitors 125 and 130 and the charging device 105, since the only thing that matters is that tension waves are applied to the capacitors 125 and 130.

(25) In order to generate a wave of high frequency tension with low electrical leakages, the converter 135 may also include a reactive circuit 145, for example, an almost-resonant, resonant or fully resonant circuit, which is set up such as to lower the electrical power (e.g. tension and/or current) applied to the active switch 155 of the switching circuit 142 to a value of substantially nil, during each transition of the active switch 155 from off to on and vice versa. In addition to the value of the electrical power, the reactive circuit 145 is preferably set up so that the time derivative of the electric power applied to the active switch 155 is also substantially nil, during each transition of the active switch 155 from on to off and possibly vice versa.

(26) It is specified here that, although the reactive circuit 145 of this example is located upstream of the galvanic isolation capacitors 125 and 130, it could alternatively also be placed between the galvanic isolation capacitor 125 and 130 and the charging device 105, or some of its components can be located upstream and others downstream of the galvanic isolation capacitors 125 and 130, without thereby modifying the effect.

(27) Further, the galvanic isolation capacitors 125 and 130 may be an integral part of the reactive circuit 145, or may be independent thereof.

(28) Purely by way of example, the converter 135 can overall present the circuit diagram shown in greater detail in FIG. 3.

(29) The converter 135 of the example of FIG. 3 comprises a first inductor 150, commonly called the choke or feed inductor, connected in series with the DC tension source 110. During normal operation, the first inductor 150 behaves essentially as a direct current generator.

(30) In series with the inductor 150, the converter 135 includes the above-mentioned active switch 155, for example a transistor (MOSFET, IGBT, BJT or other), having a head (e.g. the drain of a MOSFET type N) connected with the output terminal of the inductor 150, and the other end (e.g. the source for a MOSFET N-type) connected in circuit with the source 110, and the piloting head (e.g. the gate for a MOSFET) connected with a driver 160, i.e. with an electrical/electronic device suitable for generating and applying an active electric pilot signal to the pilot head of the switch 155.

(31) The pilot signal can for example be a square wave electrical signal with a duty-cycle of 50%.

(32) When the driving signal is ON (for example, a gate tension higher than the source for an N type MOSFET), the active switch 155 switches on (i.e. goes into saturation allowing passage of current in the active switch); when instead the drive signal is OFF (such as a lower gate tension than the source for a MOSFET), the active switch 155 is switched off (or is inhibited preventing the passage of current in the active switch).

(33) In series with the inductor 150, but in parallel with the active switch 155, the converter 135 can include a capacitor 165, the output terminal of which is connected in short circuit with the tension source 110, via an electrical branch to which a head of the active switch 155 and the second isolation capacitor 130 are also connected.

(34) In series with the inductor 150, but in parallel with both the active switch 155 and the capacitor 165, the converter 135 can comprise a further inductor 170, which is connected in series with the first isolation capacitor 125.

(35) The inductor 170 can also be divided into two or more inductors the total value of which remains the same, placed upstream or downstream of capacitor 125 and 130, without the system changing the operating principle.

(36) In this way, when the active switch 155 is switched on, the inductor 150 charges.

(37) Instead, when the active switch 155 is switched off, the current flows only to the charging device, discharging the inductor 150.

(38) Since the active switch 155 is switched on and off alternatingly by following the pilot signal, success tension impulses are applied to the isolating capacitors 125 and 130 which overall form the above-mentioned tension wave, which is then transferred to the secondary circuit 120, and then applied to the charging device 105.

(39) It is observed that in this embodiment the isolation capacitors 125 and 130 can form a part of the reactive circuit constituted overall by the reactances comprised between the converter 135 and the charging device 105.

(40) As already mentioned, this reactive circuit is set up in such a way that the electric power (e.g., tension and/or current) applied to the active switch 155, and preferably also its derivative in time, have a value of substantially nil, during each step of transition of the active switch 155 from off to on and from on to off.

(41) This set-up essentially consists of a suitable choice of the reactive components.

(42) In other embodiments, such as the one illustrated in FIG. 4, the reactive circuit 145 can include two reactive grids, of which a first reactive grid 175 for ensuring the proper functioning of the active switch 155, and a subsequent reactive grid 180, for ensuring a correct set-up of the system with a different charge from the one used to transmit the desired power.

(43) The reactive circuit 145 normally also serves as a passband filter for the tension wave that is transferred between the primary circuit 115 and the secondary circuit 120. The band of frequencies allowed to pass from the filter also depends on the set-up of the reactive circuit 145.

(44) In this regard, it is preferable for the reactive circuit 145 to be set up so as to pass one or more of the fundamental frequencies of the tension wave.

(45) Considering the specific example in which the active switch 155 is piloted by an electric signal square wave having a duty-cycle of 50%, the fundamental frequencies of the tension wave are those in odd order: the first, third, the fifth and so on. The reactive circuit 145 can therefore be set up so as to let the first fundamental frequency of the electric tension pass, in which case the converter 135 is in fact assimilable to an e-class amplifier. Alternatively, the reactive circuit 145 can be set up so as to let the third fundamental frequency of the electric tension pass, or other odd harmonics, in which case the converter 135 is in fact similar to an f-class amplifier. It is also possible for the reactive circuit 145 to be set up so as to let the fundamental frequencies of a higher order pass, or to let more fundamental frequencies pass simultaneously, in such a way as to realize an e/f class amplifier or the like.

(46) As previously mentioned, during the switching on and off cycles of the active switch 155, the inductor 150 undergoes continuous cycles of charging and discharging.

(47) In this regard, it is preferable to size the inductor 150 so as to make it fully discharge at each cycle. In other words, contrary to what happens in a classically-dimensioned choke inductor, in which the current passing through it can be considered constant, for this specific case it is possible to dimension the choke inductor 150 to oscillate the current crossing it between a maximum value and nil (avoiding however the inversions). In this way, the value of the inductor is drastically reduced. Having lower inductor values is important for this specific case because: the overall dimensions and the ohmic losses can be contained to modest proportions, and inductors can be used that are realized for example by inductors wrapped in air or another material with low losses in the core of the inductor itself.

(48) A problem that can arise with an apparatus 100 such as the one described above consists in the regulation of electric power transmitted to the charging device 105. This is the issue that limits the use of e- or f- or e/f-class amplifiers in variable charge and unknown situations a priori.

(49) To make this type of adjustment, FIG. 5 illustrates an embodiment of the apparatus 100 which differs from that of FIG. 4 only in that, downstream of the converter 135 and preferably downstream also of the isolation capacitors 125 and 130, in parallel with the rectifier 140, an electric line has been inserted comprising a capacitor 185 in series with a further active switch 190, for example a transistor (e.g. BJT, FET, MOSFET, MESFET, JFET, IGBT and others).

(50) The active switch 190 can be connected to a driver 195 suitable for generating and applying a pilot signal to the pilot head of the active switch 190, preferably a PWM electric signal or the like.

(51) When the pilot signal is ON, the active switch 190 turns on (i.e. goes into saturation allowing passage on the line); instead, when the drive signal is OFF, the active switch 190 turns off (or passes into inhibition, preventing current flow on the line).

(52) The capacitor 185 has a value that is sufficiently high to be considered a short circuit with respect to the charging device 105, when the active switch 190 is turned on.

(53) In this way, when the active switch 190 is turned on, the electrical energy transferred from the isolation capacitors 125 and 130 is predominantly diverted onto the capacitor 185, while when it is off, the charging device 105 absorbs all the energy.

(54) The electric power transmitted to the charging device 105 is therefore inversely proportional to the time in which the active switch 190 is turned on, for example to the duty-cycle of the PWM electrical pilot signal. Therefore, by adjusting the ignition time of the active switch 190, for example by adjusting the duty cycle of the PWM electrical pilot signal, it is advantageously possible to adjust the electric power transferred to the charging device 105.

(55) For example, the driver 195 can include a control circuit (not illustrated), which is configured to adjust the duty cycle of the PWM pilot signal, so as to attain a predetermined value of a characteristic parameter of the electric power to be transferred to the charging device 105.

(56) The electrical parameter that is characteristic of the electric power can be the electric power itself, or it can be the tension of the power supply of the charge or possibly the supply current transmitted to the charging device.

(57) More particularly, the control circuit may be configured to perform a feedback control which comprises: measuring the electrical parameter characteristic of the electric power transferred to the charging device, for example through one or more tension and/or current sensors applied to the secondary circuit 120; calculating the difference between the measurement of the electrical parameter characteristic of the electric power and the predetermined reference value; and adjusting the duty cycle of the PWM electrical pilot signal, such as to minimize the difference.

(58) Note that this method for regulating power can be applied to all the circuit diagrams shown in the drawings and other circuits of the same type.

(59) In addition or alternatively to this control mode, the electric power transmitted to the charging device 105 can also be adjusted by acting on the primary circuit 115, for example by suspending the generation of the pilot signal pulses of the active switch 155, in such a way as to inhibit one or more on and off cycles of the active switch 155.

(60) During the inhibited cycles the inductor 150 is not powered and the system continues to oscillate in a damped free oscillating mode. During the cycles carried out, the inductor 150 is instead supplied and the system oscillates in a forced oscillations mode.

(61) In this way, by suitably adjusting the number and/or the “suspended” pulse frequencies, the electric power transferred to the charging device 105 is effectively regulated.

(62) For this purpose, the driver 160 may comprise a control circuit (not illustrated), which is configured to adjust the number and/or the frequency of “suspended” electrical impulses of the pilot square wave, in order to follow a predetermined value of an electrical parameter characteristic of the electric power to be transferred to the charging device 105.

(63) In this case too, the electrical parameter characteristic of the electric power can be the electric power itself, or it can be the power supply tension of the charging device or possibly the supply current transmitted to the charging device.

(64) In greater detail, the control circuit may be configured to perform a feedback control which comprises: measuring the electrical parameter characteristic of the electric power transferred to the charging device, for example via one or more tension and/or current sensors applied to the secondary circuit 120 or to the primary circuit 115; calculating the difference between the measurement of the electrical parameter characteristic of the electric power and the predetermined reference value; and regulating the number and/or the frequency of the “suspended” electrical impulses of the square wave drive, such as to minimize the difference.

(65) This technique of adjustment of the power can also be applied to all the circuit diagrams shown in the drawings as well as to other circuits of the same type.

(66) In addition or alternatively to the methods mentioned above, the power transmitted to the charging device 105 can also be adjusted by regulating the direct electric tension generated by the source 110.

(67) As shown in FIG. 2, the apparatus 100 may in fact comprise a DC/DC converter 200, such as a linear converter, a switching converter, or any other type, which is placed downstream of the source 110 and upstream of the switching circuit 142, for example upstream of the choke inductor 150 (with reference to the diagrams of FIGS. 3 to 5).

(68) The DC/DC converter 200 can be configured to provide a tension value at output that is different to the value of the input tension, and thus consequently modifying the electric power transmitted to the charging device 105.

(69) As in the previous cases, the DC/DC converter 200 can also include a control circuit (not shown) suitable for adjusting the tension according to a desired value of an electrical parameter characteristic of the electric power to be transferred to the electrical load 105, for example by means of a feedback control routine.

(70) In this case too the electrical parameter characteristic of the electric power can be the electric power itself, or it can be the power supply tension of the charging device or possibly the supply current transmitted to the charging device.

(71) Although this solution has been described with reference to the generic circuit of FIG. 2, it is obvious that the same may apply to all the circuit diagrams shown in the drawings as well as to others of the same type.

(72) As illustrated in FIG. 6, in an embodiment of the invention each version of the apparatus 100 described above can be realized as a converter device 250 (meaning a single component), which can be connected via cables to the electrical charging device 105.

(73) In this case, all the essential components of the apparatus 100, including in particular the converter 135, the isolation capacitors 125 and 130, the rectifier 140, any filter and tension stabilization stages and the rectifier 111 if present, can be integrated into a single “indivisible object” which can be connected on one side with the source of alternating tension 112, or with the DC tension source 110, and on the opposite side with the charging device 105.

(74) In particular, each of the isolation capacitors 125 and 130 can be realized in the usual way as a pre-assembled capacitor, which is installed as a single unit in the “indivisible object”.

(75) Even the charging device 105 may be part of that “indivisible object.”

(76) Alternatively, in a very important alternative embodiment of the invention, any version of the apparatus 100 described above can be realized as a system for wireless transmission of power between two separate devices, without galvanic connection between them.

(77) As shown in FIG. 7, said wireless transmission system thus comprises a power supply device 300 and a user device 305, separate and independent from the power supply device 300, i.e. not exhibiting any type of physical/mechanical connection with the power supply 300.

(78) The user device 305 may be any electrical/electronic device, such as a mobile phone, a computer, tablet, lighting system, television set or other, provided with its own external body or casing 310 independent of the external body or casing 315 of the supply device 300.

(79) The power supply device 300 can comprise the components of the apparatus 100 that define the primary circuit 115, including in particular the converter 135 and the rectifier 111 if present, which can be integrated into a single “indivisible object” suitable for connecting via cable with the source of alternating tension 112, or possibly with the DC tension source 110.

(80) The user device 305 can instead include the components of the apparatus 100 that define the secondary circuit 120, including in particular the rectifier 140 and the charging device 105, which can be represented by the internal batteries to be recharged and/or electronic devices to be supplied to enable the user device 305 to operate.

(81) The isolation capacitors 125 and 130 may be defined by a pair of armatures 320 incorporated in the power supply device 300, and by another pair of armatures 325 incorporated in the user device 305.

(82) Each armature 320 and 325 may be realized by any layer of conductive material 340 coated with a layer of dielectric material 345.

(83) The armatures 320 and 325 must be placed in the respective devices so that by nearing the user device 305 to the power supply device 300, for example by placing the former on the latter, the conductor layer 340 of each armature 320 realizes, with the conductor layer 340 of a corresponding armature 325, and with the dielectric material 345 which remains interposed between them, respectively the isolation capacitor 125 or the isolation capacitor 130.

(84) In this regard, the outer casing 315 of the supply device 300 may comprise a support wall 330, and the outer casing 310 of the user device may comprise a reference wall 335, which will be facing and supported on the wall of the support 330 of the feeder device 300.

(85) The armatures 320 can be applied on the external or internal surface of the support wall 330, while the armatures 325 may be applied on the external or internal surface of the wall 335.

(86) As shown in FIG. 8, each armature 320 and 325 may more precisely comprise three superposed layers, in which the conductive layer 340 is interposed between the upper dielectric layer 345 and a lower dielectric layer 350. The lower dielectric layer 350 can be supported on a substrate 355.

(87) The upper dielectric layer 345 of each armature 320 is destined to go into direct contact with the upper layer of an armature 325.

(88) The substrate 355 of each armature 320 can be a portion of the supporting wall 330 of the supply device 300, while the substrate 355 of each armature 325 may be a portion of the reference wall 335 of the user device 305.

(89) The substrate 355 may be made of any conductive or dielectric material, provided it is sufficiently distant from the conductive layer 340. If, however, is very close to the conductive layer 340, it is better for the substrate 355 to be a dielectric characterized by low leakage and low dielectric constant when stressed by the electric field which varies over time. If the substrate 355 is a dielectric material, the lower dielectric layer 350 could be absent.

(90) The lower dielectric layer 350, if present, is preferably characterized by low leakage and low relative dielectric constant, so that the electric field propagates little in the direction of the substrate.

(91) The conductive layer 340 can be of any electrically conductive or semiconductive material, possibly doped, although the best results are obtained with low resistivity materials.

(92) The upper dielectric layer 345 should preferably enable the best possible electrical coupling between the conductive layers 320 of the armatures 320 and the armatures 325. Therefore, the upper dielectric layer 345 is preferably as thin as possible, characterized by low leakages and a high relative dielectric constant.

(93) In this way, the electrical charging device 105 of the user device 305 may be powered or recharged, without any galvanic connection, simply by placing the plates 325 of the user device 305 on the armatures 320 of the feeder device 300, such that the conductive layers 340 and the upper dielectric layers 345 of the armatures 320 and 325 realize the first and the second isolation capacitors 125 and 130 of the apparatus 100, enabling the transferring of power to the charging device 105.

(94) With the proposed layout, by virtue of using a high frequency resonant converter 135 (e.g. class “e”, “f” or “elf”), or resonant with higher harmonics than the pilot, allowing high power frequencies of the armatures 320 and 325, armatures 320 and 325 of very small dimensions are possible, such as to be easily housed internally of electronic devices in common use such as cell-phones, computers, cameras, MP3 players, lighting systems, for example LED systems, television sets and more besides.

(95) At the same time, it can be guaranteed that the tension attained by the armatures 320 and 325 is extremely low (for example a few tens of volts), which avoids any risk to the user even in the absence of the control circuits.

(96) In this way very high energy efficiency is ensured, as well as a drastic reduction in overall dimensions, low working tensions, high transmitted power, and low production costs.

(97) Naturally a technical expert in the sector might make numerous modifications of a technical-applicational nature to what has been described herein above, without forsaking the scope of the present invention, as claimed in the following.

REFERENCES

(98) 100 apparatus 105 electrical load 110 source of direct tension 111 rectifier 112 source of alternating current 115 primary circuit 120 secondary circuit 125 first capacitor 130 second capacitor 135 converter 140 rectifier 142 switching circuit 145 reactive circuit 150 inductor 155 active switch 160 driver 165 capacitor 170 inductor 175 first reactive grid 180 second reactive grid 185 capacitor 190 active switch 195 driver 200 DC/DC converter 250 converter device 300 supply device 305 user device 310 external casing 315 external casing 320 armature 325 armature 330 support wall 335 reference wall 340 conductor layer 345 upper dielectric layer 350 lower dielectric layer 355 substrate