IT202000014608A1 - SYSTEM FOR TRANSFERRING ELECTRIC POWER TO AN ELECTRIC LOAD - Google Patents

Description

DESCRIPTION

of the Italian Patent for Industrial Invention entitled:

?SYSTEM TO TRANSFER ELECTRIC POWER

TO AN ELECTRIC LOAD?

field of technique

The present invention relates to a system for transferring electric power to an electric load. The electrical load can be, for example, any electrical or electronic device that must be electrically powered to allow it to function and/or to charge the internal batteries of the device itself. Classic examples of this type of electrical/electronic devices include, but are not limited to, smartphones, computers, laptops, tablets, televisions, household appliances, home automation systems, servers and many other similar devices.

Known technique

A currently widespread solution for transferring electrical power to an electrical load? that of using a converter, or rather an electrical circuit configured in such a way as to transform an input voltage into a voltage suitable for supplying the load.

For example, AC/DC converters suitable for transforming an alternating voltage into a direct voltage, DC/AC converters suitable for transforming a direct voltage into an alternating voltage and also DC/DC or AC/AC converters suitable for transforming a direct voltage are known. / alternating into another direct / alternating voltage but having different characteristics.

To guarantee greater safety of use and robustness, all these converters can be made according to an isolated configuration, i.e. they can include a primary electric circuit connected to the input voltage and a secondary electric circuit connected to the electric load, which are galvanically isolated from each other .

A very popular strategy to galvanically isolate the primary circuit from the secondary circuit of a converter? to use inductive coupling.

A typical implementation of this strategy ? constituted by the flyback type AC/DC converter, in which the galvanic isolation ? obtained by means of a transformer which allows an electromagnetic coupling between the primary circuit and the secondary circuit.

Another example of this strategy? provided by wireless transmission systems of electric power which use inductive coils, of which at least one transmission coil placed in the primary circuit and at least one receiving coil placed in the secondary circuit.

When the two inductive coils are brought near each other, they create an electromagnetic coupling which guarantees the transfer of electric power between the two circuits.

Another strategy to galvanically isolate the primary circuit from the secondary circuit of a converter? that of separating them by means of a pair of capacities? insulation, which create a capacitive coupling capable of transmitting electrical power.

The advantages of capacitively isolated converters are many, but they mainly materialize in the possibility? to greatly reduce the overall dimensions, thanks to the elimination of the transformer and the possibility? to increase the operating frequencies (reaching for example hundreds of kHz, MHz, tens of MHz or hundreds of MHz).

Another advantage of these capacitively isolated converters? in the fact of being able to achieve a? functioning efficiency pi? high, which typically remains stable for both light electrical loads and heavy electrical loads, rather than? a tendentially low efficiency with peaks only for certain specific load ranges, as typically occurs in transformer-isolated converters.

Regardless of these considerations, in both categories of isolated converters, both those based on inductive coupling and those based on capacitive coupling, the primary circuit generally takes the form of a wave generator, i.e. a switching type electric circuit capable of excite the power transmission elements, i.e. inductances or capacitors, with a high-frequency voltage wave.

In particular, for all the types of converters outlined above, ? generally advantageous to increase the pi? possible the frequency of the voltage wave, in order to make it more? compact all components and transmit more power to the electrical load.

For this reason, especially in converters with capacitive coupling, but also in converters with inductive coupling, it is useful to use wave generators based on resonant circuit diagrams, for example based on resonant class D circuits, E, F, E/F, E<-1>, F<-1 >or similar.

In fact, this type of circuit allows to drastically reduce the dynamic losses in the active components (switches, for example MOSFET), so such as electromagnetic emissions (EMI), and to considerably increase the maximum operating frequency of the circuit, to the benefit of overall dimensions, weight and costs.

An example of a resonant circuit, which is used as a wave generator in a converter isolated by capacitive coupling, ? illustrated in international patent application WO2013150352.

One of the few drawbacks of this architecture? represented however by the necessity? to put a choke inductance of great value between the supply voltage of the circuit and the active switch.

This choke inductance should in fact have a theoretically infinite value, in order to substantially behave as a current generator, which charges itself, during the time interval in which the active switch is? turned on, and is discharged by feeding the circuit with a roughly constant current, during the time interval in which the active switch is? worn out.

Clearly in real circuits the choke inductance does not have an infinite value but still very large.

The presence of this large choke inductance, through which the currents useful for powering the load circulate, considerably increases the dimensions of the circuit and, due to the parasitic phenomena typical of real inductances, such as magnetic hysteresis for example, the parasitic currents in magnetic materials, the skin effect and the Joule effect significantly reduce their efficiency.

Exhibition of the invention

In the light of the foregoing, an object of the present invention is that of providing a solution which allows the aforementioned drawbacks of the prior art to be resolved, or at least significantly reduced.

Another purpose? that of achieving this objective in the ambit of a simple, rational and cost-effective solution? possible content.

These and other objects are achieved by the characteristics of the invention set forth in the independent claim 1. The dependent claims outline preferred and/or particularly advantageous aspects of the invention.

In particular, an embodiment of the present invention provides a system for transferring electric power to an electric load, comprising:

- a source of direct electric voltage, ed

- at least one wave generator capable of converting the direct electric voltage into voltage waves to be transmitted to the electric load,

wherein said wave generator comprises at least:

- an active switch provided with two connection terminals and able to be controlled by an electric piloting signal between a saturation condition, in which it allows the passage of electric current between said connection terminals, and an interdiction condition, in which it prevents said passage of electric current, ed

- a resonant circuit sized to reduce (preferably cancel) the electric power applied to said active switch in the instants in which said active switch switches from the saturation condition to the cut-off condition and vice versa,

wherein said resonant circuit comprises at least:

- a central electrical node to which ? connected a first connection terminal of the active switch,

- a first electrical branch extending between said central electrical node and a first terminal,

- a second electrical branch extending between said central electrical node and the first terminal or between said central electrical node and a further terminal connected to a reference voltage,

- a resonance inductance placed on the first electric branch, ed

- a capacity? of resonance placed on the second electrical branch.

Thanks to this solution, at the central electrical node of the resonant circuit, it is advantageously possible to obtain a waveform of the electric voltage equal, or in any case completely analogous, to that obtainable by means of a wave generator based on a resonant circuit structure, therefore Zero Voltage or Zero Current Switching (ZVS or ZCS) for example in class And or similar.

Consequently, the wave generator proposed above has the advantage of reducing the electrical losses during the switching phases of the switch and therefore of being able to increase the operating frequencies.

Compared to traditional wave generators, the wave generator proposed above also has the notable advantage of not requiring bulky choke inductances, achieving a significant reduction in the dimensions and costs of the system, as well as increasing its efficiency.

Starting from the basic scheme outlined above, the wave generator can? be connected to the load in several different ways.

According to one embodiment of the invention, the electrical load can be connected to the first or second electrical branch of the resonant circuit, so that said first or second electrical branch is capable of absorbing active electrical energy in virtue of of the electrical load connected to it.

In this way, ? in fact, it is possible to reduce the number and dimensions of the components that make up the entire system, which can? be more? compact and economical.

For example, one aspect of this embodiment provides that the electrical load may be placed on the first electrical branch of the resonant circuit in series with the resonant inductance.

Thanks to this solution, ? possible to obtain a structurally very simple system.

According to a variant of this solution, the electric load could be placed in a secondary circuit, which is galvanically isolated from the first electrical branch to which ? magnetically connected by inductive coupling. In this way, an isolated type system is obtained which allows to increase the safety of use and the sturdiness.

The inductive coupling can? comprising for example the resonance inductance and a coupling inductance located in the secondary circuit and capable of inductively coupling with the resonance inductance.

Thanks to this solution, the resonance inductance can? perform the dual function of resonator and transmitter of the electric power, saving components and therefore simplifying the system.

Pi? specifically, the inductive coupling pu? include a transformer equipped with a magnetic core on which ? wound a primary winding, which forms at least partially the resonance inductance, and a secondary winding, which forms at least partially the coupling inductance.

In this way ? it is possible to guarantee particularly safe and efficient inductive coupling.

Alternatively, the inductive coupling could comprise a wireless transmit coil, which forms at least partially the resonant inductance, and a wireless receive coil, which forms at least partially the coupling inductance.

In this way, a wireless transmission system of the electrical power is created by inductive way which allows, for example, to install the electrical load and the wireless receiving coil in a device (e.g. smartphone, laptop or other) which is separate and mobile with respect to the device (e.g. charging base) where? installed the wireless receiving coil and the wave generator connected to the DC voltage source.

A variant of the embodiment under examination provides that the electric load can be placed on the second electric branch of the resonant circuit in series with the capacitance? of resonance.

In fact, this solution also allows to obtain a structurally very simple system.

For example, the electrical load could be placed in a secondary circuit, which is galvanically isolated from the second electrical branch to which ? electrically connected by capacitive coupling.

In this way, an isolated type system is obtained which allows to increase the safety of use and the sturdiness.

Compared to the previously mentioned inductive coupling, this capacitive coupling also has the advantage of reducing overall dimensions, increasing efficiency and allowing higher operating frequencies.

The capacitive coupling can? include, for example, at least one pair of capabilities? isolation, each of which constitutes at least partially the capacity? of resonance.

In this way ? in fact it is advantageously possible to obtain a completely isolated system.

The capabilities? insulation can be made up of capacitance? discrete, i.e. from inseparable capacitive components.

Alternatively, each of these capacities? isolation could comprise a wireless transmission frame and a wireless reception frame able to face said wireless transmission frame.

In this way a wireless transmission system of the electrical power is created via capacitance which allows, for example, to install the electrical load and the wireless reception array in a device (e.g. smartphone, laptop or other) which is separate and mobile with respect to the device (e.g. charging base) in which the wireless transmission frame and the wave generator connected to the DC voltage source are installed.

An alternative embodiment of the present invention provides that the system can comprise an electrical connection branch extending between the central electrical node and the first terminal or between the central electrical node and a further terminal connected to a reference voltage, and that the load electricity can be connected to said electrical connection branch, so that the electrical connection branch is able to absorb active electrical energy in virtue of of the electrical load connected to it.

Even like this? in fact, it is possible to effectively transmit the voltage wave generated by the wave generator to the electric load, always using a reduced number of components.

For example, the electrical load can? be placed directly on said electrical connection branch.

Thanks to this solution ? possible to obtain a structurally very simple system.

According to a variant of this solution, the electric load could be placed in a secondary circuit, which is galvanically isolated from the electrical connection branch to which ? electrically connected by capacitive or inductive coupling.

In this way, in fact, an isolated type system is obtained which allows to increase the safety of use and the sturdiness.

Also in this case, the inductive or capacitive coupling can? be realized by inseparable components (e.g. transformer or discrete capacitors) or by separable components (e.g. wireless coils or armatures), according to the same modalities? outlined above.

A different aspect of the invention provides that the system can comprise at least two or more? of the wave generators outlined above, which are configured to transmit voltage waves out of phase with each other, preferably in push-pull, to the electric load.

In this way, a multi-phase system is obtained which allows to achieve multiple advantages, including that of increasing the power transmitted to the electrical load for the same of supply voltage, to reduce the voltage ripple on the electrical load and/or to improve the power factor of the system.

Another aspect of the invention, applicable to all the embodiments outlined above and to their variants, provides that the system can comprise a rectifier adapted to receive the voltage wave generated by the wave generator, to convert said voltage wave into a rectified voltage and to apply said rectified voltage to the electrical load.

Thanks to this solution, the electrical load can be supplied with a direct voltage or similar to a direct voltage.

According to another aspect of the invention, the DC voltage source can in turn, it comprises a rectifier adapted to receive an alternating voltage at the input and to convert said alternating voltage into the direct voltage which feeds the wave generator.

In this way the system becomes in practice an AC/DC or AC/AC converter that can? be advantageously connected to a common electrical distribution network.

However, it is not excluded that, in other embodiments, the direct voltage source may comprise a direct voltage generator or a battery. A further aspect of the invention provides that the resonant circuit of the wave generator can comprise a capacitance of tank connected in parallel to the active switch.

The presence of this ability? of tank allows to reduce the electrical losses that can occur in the active switch during the transients from the saturation condition (on) to the interdiction condition (off).

In fact, in the moment of shutdown of the active switch, the capacitance? of tanks ? discharges and forms a low impedance path capable of reducing the current in the active switch and therefore the losses.

If the capacity of tank were not sufficient, the resonant circuit could include a further inductance placed in series between the central electrical node and the active switch.

In this way, the resonant circuit will understand? substantially a first LC resonator realized by the resonance inductance and by the capacitance? resonance and a second resonator LC made by the capacity? of tank and from said further inductance.

These two LC resonators can be tuned in such a way as to ensure substantially the same waveform on the switch as a ZVS circuit in the ignition phase (therefore zero voltage and low losses in ignition) and to significantly reduce or cancel the current on the circuit-breaker. switch active in the shutdown phase, cos? to ensure or approach in the shutdown phase to a particularly advantageous ZCS condition why? low loss.

Brief description of the figures

Further characteristics and advantages of the invention will become apparent from reading the following description provided by way of non-limiting example, with the aid of the figures illustrated in the attached tables.

Figure 1 ? the general diagram of a system for transferring electric power according to an embodiment of the present invention.

Figure 2 ? the electrical diagram of a wave generator usable in the system of figure 1.

Figure 3 ? the electrical diagram of another wave generator that can be used in the system of figure 1.

Figures 4 and 5 show two variants respectively of the wave generator of figure 2 and of figure 3.

Figure 6 ? a graph showing a possible shape of the voltage wave obtainable at the central electrical node of the wave generators according to figures 2 and 3 as a function of the driving signal.

Figure 7 ? the wiring diagram of a first mode? connection of the electric load to the wave generators of figures 1 and 2.

Figures 8 to 10 show as many variants to the scheme of figure 7.

Figure 11 ? the wiring diagram of a second mode? connection of the electric load to the wave generators of figures 1 and 2.

Figures 12 to 15 show as many variants to the diagram in figure 11.

Figure 16 ? the wiring diagram of a third mode? connection of the electric load to the wave generators of figures 1 and 2.

Figures 17 to 21 show as many variants to the diagram of figure 16.

Figure 22 ? the wiring diagram of a fourth mode? connection of the electric load to the wave generators of figures 1 and 2.

Figures 23 to 29 show as many variants of the diagram in figure 22.

Figure 30 ? the wiring diagram of a system capable of supplying two electrical loads at the same time.

Figure 31 ? the electrical diagram of a further embodiment of the present invention.

Figures 32 to 36 show as many variants of the embodiment of figure 31.

Detailed description

An embodiment of the present invention provides a system 100 for transferring electric power from a source of direct electric voltage 105, or at least comparable to a direct voltage, to an electric load 110.

The electric load 110, which ? generally represented with the symbol of an electric resistance, pu? be any electrical or electronic device that must be electrically powered to allow it to function and/or to charge the internal batteries of the device itself.

Classic examples of electrical/electronic devices of this type are computers, tablets, smartphones, televisions, household appliances, home automation systems, servers and many others.

In some embodiments, the DC voltage source 105 can be a DC generator or a battery.

In other embodiments, the DC voltage source 105 can instead comprise a rectifier 115 able to receive an alternating voltage at the input coming from an alternating voltage source 120, to convert said alternating voltage into a rectified voltage more? or less assimilable to a direct voltage and to supply said direct voltage at the output.

The alternating voltage source 120 can? be, for example, a common electrical distribution network, which pu? be capable of supplying an alternating voltage of variable value depending on the country or use (e.g. industrial or domestic). Purely by way of example, the alternating voltage source 120 can? be a 50-60Hz, 90-260V AC network.

In general terms, the rectifier 115 pu? comprising a first input terminal 125 and a second input terminal 130, which can be connected to the alternating voltage source 120, so that the latter is capable of applying an alternatively variable electric voltage difference between these two terminals over time (alternating voltage).

For example, the second input terminal 130 of the rectifier 115 can be connected to a reference voltage, and is generally referred to as the neutral terminal, and the alternating voltage source 120 can? be capable of applying to the first input terminal 125, generally known as the phase terminal, a voltage which varies in a sinusoidal manner over time around the average value defined by the reference voltage. AND? it should be noted how the generator 120 can be connected to the terminals 125 and 130 by exchanging the terminals without there? affects the output of the rectifier 115.

The rectifier 115 pu? further comprising a first output terminal 135 and a second output terminal 140, between which the direct electric voltage difference obtained by converting the alternating voltage received at the input is applied, where the value of the electric voltage applied to the first output terminal 135 ? generally not less than the electric voltage value applied to the second output terminal 140.

For example, the second output terminal 140 can be connected to the reference voltage while the first output terminal 135 can? be applied a constant voltage (unless the ripple), of value non-inferior to the value of the reference voltage, which ? obtained by rectifying the alternating input voltage.

The rectifier 115 pu? realized in the form of a diode bridge (for example by Graez) but it is not excluded that, in other embodiments, it could be a single diode rectifier, a combined double diode rectifier, a synchronous rectifier or other.

Possibly, the rectifier 115 pu? be provided with a filtering circuit, for example a capacitive filter, whose function ? that of stabilizing the voltage difference between the first and second output terminals 135 and 140, reducing the ripple and therefore leveling the voltage at a substantially constant value over time.

The system 100 further comprises at least one wave generator, globally indicated with 145, ie an electric circuit which is powered by the direct voltage source 105, for example by the rectifier 115, to generate a voltage wave, ie a succession of voltage pulses which follow one another with a predetermined time frequency.

Preferably, the wave generator 145 ? capable of generating a high-frequency voltage wave, typically of the order of hundreds of KHz, MHz, tens of MHz or hundreds of MHz.

In general terms, the 145 wave generator can? comprise a first input terminal 150 and a second input terminal 155, between which a substantially constant voltage difference is applied, obtained starting from the voltage supplied by the direct voltage source 105, where the value of the electric voltage applied to the first terminal entrance fee 150 ? generally higher than the electric voltage value applied to the second input terminal 155

For example, the second input terminal 155 can? be connected to the reference voltage while the first input terminal 150 can? be connected to the first output terminal 135 of the rectifier 115.

Eventually, between the rectifier 115 and the wave generator 145 can? be interposed an intermediate converter 160, which ? adapted to receive in input the voltage supplied by the rectifier 115 and to convert it into another voltage, for example in a voltage of reduced value, more? suitable for powering the wave generator 145 and/or useful for other purposes, for example to improve the power factor and/or to facilitate the control of the system 100.

The voltage wave produced at the output of the wave generator 145 is then transferred to the electric load 110.

Eventually, between the wave generator 145 and the electric load 110 can? be interposed a rectifier 175, which ? adapted to rectify the voltage wave coming from the wave generator 145, so as to convert it and obtain a rectified voltage output, for example comparable to a direct voltage, useful for powering the electric load 110.

The rectifier 175 pu? be a diode bridge based rectifier (e.g. by Graez), single diode rectifier, dual diode matched rectifier, synchronous rectifier or other.

Also in this case, the rectifier 175 pu? be provided with a filtering stage capable of stabilizing the output voltage, leveling it to a substantially constant value or in any case comparable to constant over time (except for any residual ripple, even if significant).

It should be noted that, in some embodiments, the rectifier 175 could be absent, thus obtaining a system 100 capable of supplying the electric load 110 with an alternating voltage.

To generate the voltage wave, the wave generator 145 comprises at least one active switch 180, for example a transistor (e.g. BJT bipolar junction transistor, field effect transistor FET, MOSFET, GaN, SiC, MESFET, JFET, IGBT and others), which ? adapted to turn on and off (ie to pass from an interdiction condition to a saturation condition and vice versa) upon command of a suitable electric piloting signal.

Pi? in particular, the? active switch 180 pu? comprise a first connection terminal 185 (e.g. the drain of an N-type MOSFET), a second connection terminal 190 (e.g. the source of an N-type MOSFET), and a control terminal 195 (e.g. the gate of an N-type MOSFET).

When is the switch active 180 ? off, or is in a state of interdiction, the electric current can not? slide between the first and second connection terminals 185 and 190.

Conversely, when the active switch 180 ? on, i.e. is in saturation condition, the electric current flows freely between the first and second connection terminals 185 and 190.

The commutation of the active switch 180 between these two conditions? controlled by the electric drive signal, which is applied to the control terminal 195.

In practice, when is the voltage of the electric driving signal ? greater than or equal to a certain threshold value, the active switch 180 is in a saturation condition (turned on and capable of conducting electric current).

When vice versa the voltage of the electric driving signal ? lower than the threshold value, the active switch 180 is in the interdiction condition (off).

To generate the voltage wave, the electrical driving signal can? be a periodic signal which varies with a predetermined frequency between a minimum voltage value (possibly zero) lower than the threshold value of the active switch 180 and a maximum value higher than said threshold value.

For example, the electrical driving signal can? be a square wave signal having a constant frequency and, generally but not necessarily, a duty cycle equal to 50%.

The frequency of the electric driving signal, which in practice corresponds to the switching frequency of the active switch 180 and, therefore, to the frequency of the voltage wave generated, is preferably a choice of rather high value, for example of the order of hundreds of KHz, MHz, tens of MHz or hundreds of MHz.

The electric pilot signal can? be generated by a special driver (not shown), which pu? be suitably connected to the control terminal 195 of the active switch 180 via any system capable of transferring electrical signals (including wireless).

In addition to the active switch 180, the wave generator 145 also includes a resonant circuit 200, such as a fully resonant or nearly resonant reactive circuit.

The 200 resonant circuit ? in general, an electrical circuit that includes one or more? reactors, for example, one or more? capacity? and/or inductances, which are suitably connected to each other and tuned so as to resonate at a given frequency.

The tuning of the resonant circuit 200 consists essentially in the sizing of the aforementioned reactors, in terms of capacitance respectively? and electrical inductance.

In this case, the resonant circuit 200 ? connected to the active switch 180 and ? tuned so as to reduce the electrical power (eg voltage and/or current) which is applied to the active switch 180, during each switching phase from off to on and vice versa.

Preferably, the resonant circuit 200 ? tuned so that, during each switching phase of the active switch 180, the electric power (e.g. voltage and/or current) applied to the active switch 180 is reduced to a value equal to zero or substantially equal to zero, obtaining in this way a generator of waves 145 operating in modality? zero voltage switching (ZVS) or zero current switching (ZCS).

For example, the 200 resonant circuit can? be tuned to resonate at a frequency equal to or close to the driving frequency of the active switch 180.

In this way, the electrical losses are considerably reduced during the switching cycles of the active switch 180, allowing to increase the frequency of these cycles and therefore the frequency of the voltage wave generated by them, with the result of being able to increase the power electricity transmitted, on equal terms? of applied voltage, or to be able to lower the applied voltage, to the parity? of transmitted electrical power.

Starting from these general considerations, a possible embodiment of the wave generator 145 and of the relative resonant circuit 200 ? illustrated in figure 2.

In this embodiment, the resonant circuit 200 includes a central electrical node 215, to which it can connect. the first connection terminal 185 of the active switch 180 (for example the drain of an N-type MOSFET) must be connected.

The second connection terminal 190 of the active switch 180 (for example the source of an N-type MOSFET) can? be connected to the reference voltage.

The resonant circuit 200 further comprises a first electrical branch 205, which extends from the central electrical node 215 to a first terminal 210 which can be connected (that is, coincide) with the first input terminal 150 of the wave generator 145.

The resonant circuit 200 further comprises a second electrical branch 220 which can also extend between the first terminal 210 and the central electrical node 215, so as to be connected in parallel with the first electrical branch 205.

On the first electrical branch 205 pu? be placed a resonance inductance 225 while on the second electrical branch 220 can? be placed a capacity? of resonance 230.

As previously mentioned, the resonance inductance 225 and the capacitance? resonance sensors 230 are sized (tuned) in such a way as to form a resonator which reduces, preferably cancels, the electric power (for example the voltage and/or current) which ? applied to the active switch 180 during each single switching phase.

In this way, at the central electrical node 215, ? it is advantageously possible to obtain an electric voltage VD which, as a function of the electric driving signal VG of the active switch 180, is variable over time according to the waveform represented in figure 6 or according to similar waveforms and in particular capable of guaranteeing ZVS and/or ZCS transitions of the switch 180.

In practice, it is a waveform equal or in any case analogous to those obtainable by means of a wave generator based on a circuit structure similar to a class E amplifier or based on any other ZVS and/or ZCS resonant amplifier.

By obtaining the same waveform, i.e. by generating the same voltage wave, the wave generator 145 outlined above obtains the same advantages as the resonant wave generators mentioned above, in particular in terms of reduction of electrical losses during the phases of commutation of the active switch and therefore of increase of the operating frequencies.

However, compared to these wave generators, the wave generator 145 has the notable advantage of not requiring bulky choke inductances, allowing for a significant reduction in size and cost.

The same waveform, and therefore the same advantages of the wave generator 145 shown in figure 2, can also be obtained from the wave generator 145 shown in figure 3.

This wave generator 145 differs from the previous one only in that the second electrical branch 220 of the resonant circuit 200, with its relative capacitance, is of resonance 230, extends between the central electric node 215 and a further terminal 235 connected to the reference voltage.

A variation of both of the 145 wave generators described above? illustrated respectively in figure 4 and in figure 5.

The diagrams of figures 4 and 5 differ from those of figures 2 and 3 only in that the first terminal 210 of the resonant circuit 200 ? connected to the reference voltage and that the second connection terminal 190 of the active switch 180 ? connected to (i.e. coincides with) the first input terminal 150 of the wave generator 145.

In this way, wave generators 145 are obtained which operate similarly to those of figures 2 and 3 but with the drawback that the active switch 180 is connected in floating mode and is ? then more difficult to drive, requiring for example the use of a p-MOS or an n-MOS driven through a suitable bootstrap circuit.

For this reason, although in all the implementations that will be illustrated below it is possible to connect the active switch 180 in floating mode as shown illustrated in figure 4 or 5, it is possible to connect the active switch 180 in floating mode. it is generally always preferable to connect the active switch 180 to the reference voltage as illustrated in figures 2 and 3 and in all the examples which follow.

Starting from the basic diagrams illustrated in figures 2 and 3, the wave generator 145 can be connected to the electric load 110 in different ways.

According to a first embodiment illustrated in figure 7, the electric load 110 can be placed on an electrical connection branch 240, which extends between the first terminal 210 of the resonant circuit 200 and the central electrical node 215, so that the electrical load 110 is substantially connected in parallel with the resonant inductance 225.

The capacity? of resonance 230 pu? be connected in parallel to the resonance inductance 225 according to the diagram in figure 2 (continuous line), or can? be equivalently connected to the reference voltage according to the diagram in figure 3 (dashed line).

Note that in the embodiment of Figure 7, the electrical load 110 is connected so as to directly receive the voltage wave generated by the wave generator 145 and therefore be supplied substantially with an alternating voltage.

However, if it is necessary to supply the electric load 110 with a substantially direct voltage, ? it is advantageously possible to insert the rectifier 175 along the electrical connection branch 240 upstream of the electrical load 110, so as shown in figure 8.

In both embodiments illustrated in Figures 7 and 8, the electrical load 110 is galvanically connected to the direct voltage source 105, realizing a non-insulated system.

However, the diagrams described above can be modified so as to place the DC voltage source 105 in a primary electric circuit and the electric load 110 in a secondary circuit which ? galvanically isolated from the primary circuit.

For example, in figure 9 ? illustrated a circuit diagram which differs from that of figure 8 due to the presence of two capacitances? insulation, of which a first capacity? of insulation 250 located on the electrical connection branch 240 between the first terminal 210 and the electrical load 110, for example between the first terminal 210 and the rectifier 175, and a second capacitance? of insulation 255 located on the electrical connection branch 240 between the electrical load 110 and the central electrical node 215, for example between the rectifier 175 and the central electrical node 215.

The value of the two capacities? of insulation 250 and 255 ? preferably much greater than the value of the capacity? of resonance 230, so as not to interfere with the resonant frequency of the resonant circuit 200.

For example, the value of the capabilities? insulation 250 and 255 pu? be chosen in the order of hundreds of nF or uF, against resonant frequencies in the order of MHz.

In this way, the two capacities? of insulation 250 and 255 are capable of completely galvanically isolating the primary circuit, comprising the direct voltage source 105 and the wave generator 145, from the secondary circuit, comprising the electric load 110 and the rectifier 175.

At the same time, the capabilities of insulation 250 and 255 electrically couple the primary circuit to the secondary circuit via capacitive means, allowing the voltage wave generated by the wave generator 145 to be transmitted to the electric load 110.

In some embodiments, the two capabilities insulation 250 and 255 can be capacity? discrete, i.e. inseparable components comprising a first terminal connected to the primary circuit and a second terminal connected to the secondary circuit.

In this way, the system 100 can? be made in the form of a single and inseparable device, such as an isolated power supply.

In other embodiments, each capability? insulation 250 and 255 pu? be realized by a pair of mutually separable plates, of which a transmission plate connected to the primary circuit and a receiving plate connected to the secondary circuit.

In this way, the primary circuit, including the DC voltage source 105, the wave generator 145 and the transmission plates, can be installed in a first device, while the secondary circuit, comprising at least the electric load 110, the rectifier 175 and the receiving plates, can? be installed on a second device, physically separate and movable (movable) from the first device.

For example, the first device could be configured as a charging cradle while the second device could be a charging or powering device, such as a smartphone, laptop, TV, and more.

In this way, by suitably approaching the second device to the first device, it would be possible to approach and face each transmission frame to a corresponding reception frame, reconstituting the capacitances? of insulation 250 and 255 and thus realizing? a wireless transmission system of electrical power via capacitance.

In other embodiments, the galvanic isolation between the primary circuit and the secondary circuit could be achieved by an inductive coupling system.

For example, in figure 10 ? illustrated a circuit diagram which differs from that of figure 6 due to the fact that on the electrical connection branch 240 ? a coupling inductance 260 is placed which is suitable for realizing an inductive coupling, i.e. through electromagnetic induction, with a corresponding coupling inductance 265 connected in a closed circuit with the electric load 110, for example with the interposition of the rectifier 175.

The value of the two coupling inductances 260 and 265 ? preferably much greater than the value of the resonant inductance 225, so as not to interfere with the resonant frequency of the resonant circuit 200.

In this way, the two coupling inductances 260 and 265 are capable of completely galvanically isolating the primary circuit, comprising the direct voltage source 105 and the wave generator 145, from the secondary circuit, comprising the electric load 110 and the rectifier 175.

At the same time, the coupling inductances 260 and 265 electrically connect the primary circuit to the secondary circuit inductively, allowing the voltage wave generated by the wave generator 145 to be transmitted to the electrical load 110.

In some embodiments, the coupling inductances 260 and 265 can be at least partially constituted respectively by the primary winding and the secondary winding of a transformer, for example wound around the same magnetic core.

In this way, the system 100 can? be made in the form of a single and inseparable device, such as an isolated power supply.

In other embodiments, each coupling inductor 260 and 265 can be at least partially constituted respectively by a wireless transmission coil (e.g. antenna) and a wireless electrical power reception coil (e.g. antenna).

In this way, the primary circuit, comprising the DC voltage source 105, the wave generator 145 and the coupling inductance 260, can be installed in a first device (e.g. recharging base), while the secondary circuit, comprising at least the electric load 110, the rectifier 175 and the coupling inductance 265, can? be installed on a second device (e.g. smartphone, laptop or TV), physically separate and movable (movable) from the first device.

In this way, suitably approaching the second device to the first device ? Is it possible to re-establish the inductive coupling between the coupling inductances 260 and 265, which thus realize? a wireless transmission system of electrical power by induction.

It should be noted here that, although the isolated solutions described with reference to figures 9 and 10 provide for the presence of the rectifier 175, the latter could be omitted if it were required to supply the electric load 110 with an alternating voltage.

Furthermore, although the aforementioned isolated solutions provide (in a continuous line) that the capacity? of resonance 230 is connected in parallel with the? resonance inductance 225, alternatively the capacitance? of resonance 230 could be connected to the reference voltage (in dashed line).

As illustrated in figure 11, a second modality? to connect the electric load 110 to the wave generators 145 illustrated in the diagrams of figures 2 and 3 provides that the electric connection branch 240, on which ? placed the electric load 110, extends from the central electric node 215 of the resonant circuit 200 and a further terminal 245 connected to the reference voltage.

Compared to the embodiment of figure 7, this solution therefore has the considerable advantage of having the electric load 110 referred to the reference voltage instead of floating.

Also in this case, the capacity? of resonance 230 pu? be connected in parallel to the resonance inductance 225 according to the diagram in figure 2 (continuous line), or can? be equivalently connected to the reference voltage according to the diagram in figure 3 (dotted line).

According to the diagram of figure 11, the electric load 110 directly receives the voltage wave generated by the wave generator 145 and is therefore powered substantially in alternating voltage.

However, should it be necessary to supply the electric load 110 with a substantially direct voltage,? it is advantageously possible to insert the rectifier 175 along the electrical connection branch 240 upstream of the electrical load 110, so as shown in figure 12.

In the solutions described with reference to figures 11 and 12, the electric load 110 is galvanically connected to the direct voltage source 105, realizing a non-insulated system.

Also in this case, ? however, it is possible to modify each of the diagrams described above, so that the DC voltage source 105 is placed in a primary circuit and that the electric load 110 is placed in a secondary circuit galvanically isolated with respect to the primary circuit.

For example, in figure 13 ? illustrated a circuit diagram which differs from that of figure 12 due to the presence of two capacitances? insulation, of which a first capacity? of insulation 250 located on the electrical connection branch 240 between the central electrical node 215 and the electrical load 110, for example between the central electrical node 215 and the rectifier 175, and a second capacitance? of insulation 255 located on the electrical connection branch 240 between the electrical load 110 and the terminal 245 connected to the reference voltage, for example between the rectifier 175 and said terminal 245.

The value of the two capacities? of insulation 250 and 255 ? preferably much greater than the value of the capacity? of resonance 230, so as not to interfere with the resonant frequency of the resonant circuit 200, for example in the order of hundreds of nF or uF, compared with resonant frequencies in the order of MHz.

In this way, the two capacities? of insulation 250 and 255 are capable of completely galvanically isolating the primary circuit, comprising the direct voltage source 105 and the wave generator 145, from the secondary circuit, comprising the electric load 110 and the rectifier 175.

At the same time, the capabilities of insulation 250 and 255 electrically couple the primary circuit to the secondary circuit via capacitive means, allowing the voltage wave generated by the wave generator 145 to be transmitted to the electric load 110.

In some embodiments, the two capabilities insulation 250 and 255 can be capacity? discreet.

In other embodiments, each capability? insulation 250 and 255 pu? a pair of mutually separable plates can be made, of which a transmission plate connected to the primary circuit and a receiving plate connected to the secondary circuit.

In this way, the primary circuit, including the DC voltage source 105, the wave generator 145 and the transmission plates, can be installed in a first device (e.g. recharging base), while the secondary circuit, comprising at least the electric load 110, the rectifier 175 and the receiving fixtures, can? be installed on a second device (e.g. smartphone, laptop or TV), physically separate and movable (movable) from the first device.

In this way, suitably approaching the second device to the first device ? Is it possible to approach and face each transmission frame to a corresponding receiving frame, reconstituting the capacities? of insulation 250 and 255 that realize cos? a wireless transmission system of electrical power via capacitance.

However, if it were not necessary to realize a wireless transmission of the electric power and/or it was not necessary a complete galvanic isolation between the primary circuit and the secondary circuit, the capacitance? of insulation 255 could be eliminated as illustrated in figure 14.

In this way you would have a single capacity? insulation 250 designed to act as a block of direct voltage, which ? located on the electrical connection branch 240 between the central electrical node 215 and the electrical load 110, for example between the central electrical node 215 and the rectifier 175.

Alternatively, one could equivalently omit the ability? of insulation 250 and leave only the capacity? of insulation 255 suitable for blocking the direct voltage.

In other embodiments, the galvanic isolation between the primary circuit and the secondary circuit could be achieved by an inductive coupling system.

For example, in figure 15 ? illustrated a circuit diagram which differs from that of figure 11 due to the fact that on the electrical connection branch 240 ? a coupling inductance 260 is placed which is suitable for realizing an inductive coupling, i.e. through electromagnetic induction, with a corresponding coupling inductance 265 connected in a closed circuit with the electric load 110, for example with the interposition of the rectifier 175.

The value of the two coupling inductances 260 and 265 ? preferably much greater than the value of the resonant inductance 225, so as not to interfere with the resonant frequency of the resonant circuit 200.

In this way, the two coupling inductances 260 and 265 are capable of completely galvanically isolating the primary circuit, comprising the direct voltage source 105 and the wave generator 145, from the secondary circuit, comprising the electric load 110 and the rectifier 175.

At the same time, the coupling inductances 260 and 265 electrically connect the primary circuit to the secondary circuit inductively, allowing the voltage wave generated by the wave generator 145 to be transmitted to the electrical load 110.

In some embodiments, the coupling inductances 260 and 265 can be at least partially constituted respectively by the primary winding and the secondary winding of a transformer, for example wound around the same magnetic core.

In this way, the system 100 can? be made in the form of a single and inseparable device, such as an isolated power supply.

In other embodiments, each coupling inductor 260 and 265 can be at least partially constituted respectively by a wireless transmission coil (e.g. antenna) and a wireless electrical power reception coil (e.g. antenna).

In this way, the primary circuit, comprising the DC voltage source 105, the wave generator 145 and the coupling inductor 260, can be installed in a first device (e.g. recharging base), while the secondary circuit, comprising at least the electric load 110, the rectifier 175 and the coupling inductance 265, can? be installed on a second device (e.g. smartphone, laptop or television), physically separate and movable (movable) from the first device.

In this way, suitably approaching the second device to the first device ? Is it possible to re-establish the inductive coupling between the coupling inductances 260 and 265, which thus realize? a wireless transmission system of electrical power by induction.

Although all the isolated solutions described with reference to figures 13, 14 and 15 provide for the presence of the rectifier 175, the latter could be omitted if it were required to supply the electric load 110 with an alternating voltage.

Furthermore, although the aforementioned solutions provide that the capacity? of resonance 230 is connected in parallel with the resonance inductance 225 (continuous line), alternatively the capacitance? of resonance 230 could be connected to the reference voltage (dashed line).

A third way? to connect the electric load 110 to the wave generators 145 illustrated in the diagrams of figures 2 and 3 ? represented in figure 16 and provides that the electric load 110 can be placed directly on the first electric branch 205 in series with the resonance inductance 225.

Also in this case, the capacity? of resonance 230 pu? be connected in parallel to the resonance inductance 225 according to the diagram in figure 2 (continuous line), or can? be equivalently connected to the reference voltage according to the diagram in figure 3 (dotted line).

In the diagram of figure 16, the electric load 110 ? connected so as to directly receive the voltage wave generated by the wave generator 145 and therefore be supplied substantially with alternating voltage.

However, should it be necessary to supply the electric load 110 with a substantially direct voltage,? it is advantageously possible to insert the rectifier 175 along the first electrical branch 205 upstream of the electrical load 110, so as shown in figure 17.

Starting from these non-isolated schemes ? Is it then possible to develop solutions in which the direct voltage source 105 is placed on a primary circuit and in which the electric load 110 is placed in a secondary circuit, which ? galvanically isolated from the primary circuit.

For example, in figure 18 ? illustrated a circuit diagram which differs from that of figure 17 due to the fact that the resonance inductance 225, located on the first electrical branch 205, is suitable for realizing an inductive coupling, ie through electromagnetic induction, with a corresponding coupling inductance 300, which ? connected in closed circuit with the electric load 110, for example with the interposition of the rectifier 175.

In this way, the resonant inductance 225 and the coupling inductance 300 are capable of completely galvanically isolating the primary circuit, comprising the direct voltage source 105 and the wave generator 145, from the secondary circuit, comprising the load circuit 110 and the rectifier 175. At the same time, the resonant inductance 225 and the coupling inductance 300 electrically connect the primary circuit to the secondary circuit by induction, allowing the voltage wave generated by the wave generator 145 to be transmitted to the electrical load 110.

Compared to the inductively isolated systems illustrated in Figures 9 and 14, this solution allows for a reduction in the number of components, since one of the coupling inductances coincides with the resonance inductance 225, and also allows for a considerable reduction in the dimensions and costs of the entire system, as the inductances 225 and 300 of the diagram of figure 18, also having the function of resonance inductances, can be much more? smaller than those used in the previous diagrams.

Observing the scheme of figure 18, ? in fact it is evident how the overall resonance inductance is given, not only by the inductance indicated as resonance inductance 225 of the primary circuit, but also by the coupling inductance 300 of the secondary circuit, which is? magnetically coupled with a coupling coefficient k typically lower than the unit? (where k=1 would correspond to an ideal match).

Similarly to the previous cases, some embodiments can provide that the resonant inductance 225 and the coupling inductance 300 are at least partially constituted respectively by the primary winding and the secondary winding of a transformer, for example wound around the same core magnetic.

Other embodiments can instead provide that the resonant inductance 225 and the coupling inductance 300 can be at least partially constituted respectively by a wireless transmission coil (e.g. antenna) and a wireless reception coil (e.g. antenna) of the electric power. In this way, the primary circuit, comprising at least the DC voltage source 105, the wave generator 145 and the resonant inductance 225, can be installed in a first device, while the secondary circuit, comprising at least the electric load 110, the rectifier 175 and the coupling inductance 300, can? be installed on a second device, physically separate and movable (movable) from the first device.

For example, the first device could be configured as a charging cradle while the second device could be a charging or powering device, such as a smartphone, laptop, TV, and more.

In this way, suitably approaching the second device to the first device ? Is it possible to re-establish the inductive coupling between the resonance inductance 225 and the coupling inductance 300, which thus realize? a wireless transmission system of electrical power by induction.

Although the solution of figure 18 provides that the capacity? of resonance 230 is connected in parallel with the resonance inductance 225 (continuous line), alternatively the capacitance? of resonance 230 could be connected to the reference voltage (dashed line).

Starting from the isolated scheme shown above ? it is also possible to develop schemes conceptually similar but based on a greater number of phases, for example but not exclusively based on two phases.

An example of this solution? illustrated in figure 19, in which the system 100 comprises at least two wave generators 145 of the type shown in figure 18.

In particular, the first terminals 210 of both wave generators 145 can coincide and form a single common node, which ? connected with the first input terminal 150, or with the direct voltage source 105, while the active switches 180 and the capacitances? of resonance 230 can be connected to the reference voltage.

Of course the skills of resonance 230 could alternatively be connected in parallel to the corresponding resonance inductances 225 and eventually be replaced by a single? of resonance 230 having the terminals respectively connected to the central electrical nodes 215 of the two wave generators 145, so? as shown in figure 20.

Regardless of these considerations, the resonance inductance 225 placed on the first electric branch 205 of each wave generator 145 can be capable of realizing an inductive coupling, ie through electromagnetic induction, with a corresponding coupling inductance 300, which ? connected in closed circuit with the electric load 110, for example with the interposition of the rectifier 175.

Also in this case, the inductive coupling between the resonant inductances 225 and the coupling inductance 300 can be achieved by transformer or by a wireless transfer solution, exactly as described above.

The active switches 180 can be controlled by respective driving signals, so that they turn on and off with the same frequency but not in phase with each other, i.e. so that the active switches 180 are not always on or off at the same time but there is always at least a small period of time, within each period of operation, in which an active switch 180 ? turned on and the other ? off and vice versa.

In this way, by suitably adjusting this period of time, ie the phase shift between the driving signals of the two active switches 180, ? is it advantageously possible to increase the power transmitted to the electric load 110 with parity? of supply voltage, reduce the voltage ripple on the electrical load 110 and/or improve the power factor of the circuit.

If the power level to be transferred to the electric load 110 is particularly high, ? otherwise? It is possible to command the two active switches 180 with driving signals in push-pull with each other, in such a way that, when an active switch 180 is turned on, the other is constantly off and vice versa, obtaining a mode? of Push-Pull type operation.

so that can these multiphase implementations work properly, ? however, it is preferable that, starting from the first common terminal 210, connected to the supply voltage, the two resonant inductances 225 (i.e. the two primary transformer windings or alternatively the two primary wireless transmission inductive coils) are wound in discordant directions, what? as shown in the diagram in figure 21.

For example, the two resonant inductances 225 can be wound respectively with a right-hand and left-hand direction.

In this way, ? in fact, it is possible to guarantee the inversion of the magnetic field generated by the two resonance inductances 225 and, at the same time, the inversion of the currents, improving the power factor of the circuit and preventing the voltage induced in the inactive resonance inductance 225 from causing current circulates in the body diode of the active switches 180.

It should be noted here that, although all the isolated solutions illustrated in figures 18 to 20 provide for the presence of the rectifier 175 in the secondary circuit, this rectifier 175 could be omitted if it were required to supply the electric load 110 with an alternating voltage.

As illustrated in figures 22 and 23, a fourth modality? to connect the electric load 110 to the wave generators 145 illustrated in the diagrams of figures 2 and 3, it provides that the electric load 110 can be placed directly on the second electric branch 220 in series with the capacitance? of resonance 230.

In particular, in the embodiment of figure 22, the second electrical branch 220, on which the capacitors are placed in series of resonance 230 and the electric load 110, extends between the first terminal 210 and the central electric node 215 of the resonant circuit 200, according to the general scheme of figure 2.

In the embodiment of figure 23, the second electrical branch 220, on which the capacitors are placed in series of resonance 230 and the electric load 110, extends instead between the central electric node 215 of the resonant circuit 200 and the terminal 235 which ? connected with the reference voltage, according to the general diagram in figure 3.

Compared to the embodiment of figure 22, this second variant therefore has the considerable advantage of having the electric load 110 referred to the reference voltage instead of floating.

In the solutions of figures 22 and 23, the electric load 110 ? connected so as to directly receive the voltage wave generated by the wave generator 145 and therefore be supplied substantially with alternating voltage.

However, should it be necessary to supply the electric load 110 with a substantially direct voltage,? it is advantageously possible to insert the rectifier 175 along the second electrical branch 220 upstream of the electrical load 110, so as illustrated in the examples of figures 24 and 25.

Regardless of the presence of the rectifier 175, the diagram of figure 24 corresponds exactly to the diagram of figure 22 while the diagram of figure 25 corresponds exactly to the diagram of figure 23.

According to a particularly advantageous variant, the rectifier 175, which ? represented in figure 25 as a generic stage of rectification, pu? be made as shown in figure 26.

In practice, the rectifier 175 pu? include a diode 305 having anode connected to the reference voltage and cathode connected to an electrical node 310 located on the second electrical branch 220 between the capacitance? of resonance 230 and the electric load 110.

The rectifier 175 pu? further comprise an inductance 315 located along the second electrical branch 220 between the electrical node 310 and the electrical load 110, and possibly a capacitance? 320 having a first terminal referred to the reference voltage and a second terminal connected to an electrical node 325 interposed between the inductance 315 and the electrical load 110.

Thanks to this solution, a very versatile circuit is created, which ? able to realize substantially all the functionalities? of a non-inverting Buck-Boost converter, but which, compared to a conventional non-inverting Buck-Boost converter, has fewer components, advantageously reducing its overall dimensions and costs.

Normally, in fact, a non-inverting Buck-Boost converter consists of two stages in cascade, of which a first Boost stage and a second Buck stage, which therefore require the presence of at least two active switches and at least two diodes.

The active switches of this traditional Buck-Boost converter are also floating switches, which are difficult to drive and require bootstrap circuitry.

Another known solution to obtain the non-inverting Buck-Boost effect? that of using a SEPIC converter, which for? need? of an expensive and bulky transformer.

The circuit illustrated in figure 26 instead obtains the non-inverting Buck-Boost effect with a very reduced complexity. circuitry, comparable with a classic inverting Buck-Boost circuit or with a Cuk converter.

Compared to the Cuk converter, the circuit illustrated in figure 26 differs however in the direction of the diode 305 and, above all, in a completely different dimensioning of the reactive components, from which an extremely different operating principle follows.

In fact, the Cuk converter bases its steady state operation on the use of inductances as continuous sources of current and on the use of these currents for a controlled charge and discharge of the capacitive elements in the sub-phases of the operating period.

On the contrary, the circuit of figure 26 is based on the resonance between the resonant inductance 225 and the capacitance? of resonance 230 and on the fact that the capacity? of resonance 230 is used both as a capacity? of resonance and as a blocking barrier of the direct voltage (DC), obtaining waveforms of the voltages and of the electric currents which are completely different from those obtainable by the Cuk converter.

This resonant approach is naturally also reflected in the sizing of the reactive components involved, which are considerably more? smaller than those of the Cuk converter.

Thanks to the resonance it is also possible to guarantee a considerably higher efficiency than the Cuk converter, significantly reducing also the electromagnetic emissions (EMI), since? the commutations of the active switch 180 are of the soft switching type, for example zero voltage switching (ZVS) and/or zero current switching (ZCS).

The voltage wave downstream of the capacitance? of resonance 230 is then rectified by the rectifier 175, in which the inductance 315, contrary to the resonance inductance 225, can? be sized so as to essentially act as a current generator.

In other words, the inductance 315 can? have a high inductive value, for example large enough to make the current ripple negligible with respect to the average current value in the inductance 315 itself. Naturally, the diagram illustrated in figure 26, in which the rectifier 175 is composed of a simple diode 35 and an LC filter formed by the inductance 315 and the capacitance? 320, represents the version pi? simple circuit Buck-Boost non-inverting that can? be obtained starting from the wave generator 145 proposed above.

In other embodiments pi? complex and more energy efficient? at least for low current values, the diode 305 could for example be replaced with a further active switch controlled so as to carry out a synchronous rectification.

Also in this case, the circuit would not result however particularly complex, since? the further active switch would be referred to the reference potential and would therefore be extremely easy to drive, even at high frequencies.

A possible variant which allows to further increase the performance of the Buck-Boost circuit of Figure 26 consists in making the rectifier 175 resonant as well, in a similar way to what is achieved with a class E rectifier or in any case with resonant rectifiers.

From the circuit point of view, the scheme would remain substantially the same (possibly with additional reactive components useful to simplify the tuning, for example one or more additional capacitors in parallel with the diode 305), but the inductance 315 would have a reduced inductive value, useful in particular to resonate with the remaining circuit network, in order to reduce and possibly cancel the dynamic losses in the diode 305 or, in the case of synchronous rectification, in the further active switch which would replace the diode 305.

Starting from the diagrams illustrated in figures 22 to 26 ? then is it possible to develop isolated solutions, in which the DC voltage source 105 ? placed in a primary circuit and in which the electric load 110 ? placed in a secondary circuit, which ? galvanically isolated with respect to the primary circuit but ? electrically coupled to it by means of a capacitive coupling system.

For example, in figure 27 ? illustrated a circuit diagram identical to that of figure 24 with the exception of the fact that the capacitance? of resonance 230 ? divided into two capacities? of resonance 230A and 230B, which are placed on the second electrical branch 220, respectively between the first terminal 210 of the resonant circuit 200 and the electrical load 110, for example upstream of the rectifier 175, and between the electrical load 110 and the electrical node plant 215, for example downstream of the rectifier 175.

In this way, the two capacities? of resonance 230A and 230B also act as capacitance? insulation and are capable of completely galvanically isolating the primary circuit, comprising the direct voltage source 105 and the wave generator 145, from the secondary circuit, comprising the electric load 110 and the rectifier 175.

At the same time, the capabilities resonance coils 230A and 230B electrically connect the primary circuit to the secondary circuit via capacitance, allowing the voltage wave generated by the wave generator 145 to be transmitted to the electric load 110.

An alternative solution, but which achieves the same effects set out above, ? illustrated in figure 28 and provides a circuit diagram identical to that of figure 25 (and therefore possibly feasible as that of figure 26) with the exception of the fact that, also in this case, the capacitance? of resonance 230 ? divided into two capacities? of resonance 230A and 230B, which are placed on the second electric branch 220, respectively between the central electric node 215 of the resonant circuit 200 and the electric load 110, for example upstream of the rectifier 175, and between the electric load 110 and the terminal 235 what? connected to the reference voltage, for example downstream of the rectifier 175.

In both embodiments shown, the two capacities? of resonance 230A and 230B can be capacitance? discrete, i.e. inseparable components comprising a first terminal connected to the primary circuit and a second terminal connected to the secondary circuit.

In this way, the system 100 can? be made in the form of a single and inseparable device, such as an isolated power supply.

In other embodiments, each capability? of resonance 230A and 230B pu? be realized by a pair of mutually separable plates, of which a transmission plate connected to the primary circuit and a receiving plate connected to the secondary circuit.

In this way, the primary circuit, including the DC voltage source 105, the wave generator 145 and the transmission plates, can be installed in a first device, while the secondary circuit, comprising at least the electric load 110, the rectifier 175 and the receiving plates, can? be installed on a second device, physically separate and movable (movable) from the first device.

For example, the first device could be configured as a charging cradle while the second device could be a charging or powering device, such as a smartphone, laptop, TV, and more.

In this way, suitably approaching the second device to the first device ? Is it possible to approach and face each transmission frame to a corresponding receiving frame, reconstituting the capacities? of resonance 230A and 230B that realize cos? a wireless transmission system of electrical power via capacitance.

? it should be noted that, compared to the inductively isolated systems illustrated in figure 18, the isolated systems with capacitive coupling illustrated in figures 27 and 28 have considerable advantages in terms of space reduction, increased efficiency and the possibility of to operate at high frequency.

The systems illustrated in Figures 27 and 28 are also advantageous over the other capacitively isolated systems which have been illustrated with reference to Figures 9 and 13.

The systems of figure 27 and 28 foresee in fact that the capacities? of resonance 230A and 230B act simultaneously as resonators and capacitance? insulation and barrier for DC voltage.

In this way, the number of circuit components and the capacitances are advantageously reduced. of resonance 230A and 230B can be much more? small compared to the capacity? of insulation 250 and 255 of figure 9 or of figure 13 (for example they can be selected in the order of pF, tens of pF, hundreds of pF, nF or tens of nF).

Capacity? small in size, they reduce overall dimensions and costs, have fewer losses due to parasitic phenomena and above all make it possible to create circuits without problems from a certification point of view in the case of isolated converters.

There are indeed rules that limit the value of the capabilities? which connect the primary circuit to the secondary circuit of isolated converters, in order not to introduce safety problems and electromagnetic emissions.

Similarly, the fact of being able to use capacity? small size makes it more? It is simple to create a capacitive wireless electric power transmission system between physically separate devices, since the geometries of the devices, and therefore the areas available on them, generally do not allow the installation of transmitting and/or receiving fixtures of large dimensions, necessary to obtain capacity? of great value, while they are absolutely compatible with the dimensions of the transmitting and/or receiving armatures that must realize capacitance? small as those generally sufficient for the diagrams of figures 27 and 28.

Although the systems of figures 27 and 28 provide for the presence of the rectifier 175, the latter could naturally be omitted if one wanted to supply the electric load 110 with an alternating voltage.

Starting from the isolated schemes shown above ? then it is possible to develop schemes conceptually similar but based on a greater number of phases, for example but not exclusively based on two phases.

An example of this solution? illustrated in figure 29, in which the system 100 comprises at least two wave generators 145 substantially identical to the one illustrated in figure 23, with the exception of the fact that the capacitances? of resonance 230 of these two wave generators 145 are connected to the opposite ends of the single electric load 110.

In practice, the first terminals 210 of the resonant circuits 200 of the two wave generators 145 can both be connected to the first input terminal 150, i.e. with the direct voltage source 105, while the central electrical nodes 215 can be mutually connected by a single second electric branch 220, common to both wave generators 145, on which both capacitors are placed? of resonance 230 of the two wave generators 145 and, in an interposed position between said capacitances? of resonance 230, the electric load 110.

In this way, the capabilities of resonance 230 also act as capacity? insulation, galvanically isolating a primary circuit, which includes the DC voltage source 105 and the wave generators 145, from a secondary circuit, which includes the electric load 110.

Also in this case, the two capacities? of resonance 230 may be capacity? discrete or they can be individually realized by a transmission plate and a receiving plate, in the ambit of a wireless transmission system of the electric power by capacitive way as already? described more times previously.

The active switches 180 of the two wave generators 145 can be controlled by respective driving signals, in such a way that they turn on and off with the same frequency but not in phase with each other, i.e. in such a way that the active switches 180 are not always on or off simultaneously but there is always at least a small period of time, within each period of operation, in which an active switch 180 ? turned on while the other switch is active 180 ? off and vice versa.

In this way, by suitably adjusting this period of time, ie the phase shift between the driving signals of the two active switches 180, ? is it advantageously possible to increase the power transmitted to the electric load 110 with parity? of supply voltage, reduce the voltage ripple on the electrical load 110 and/or improve the power factor of the circuit.

If the power level to be transferred to the electric load 110 is particularly high, ? otherwise? It is possible to command the two active switches 180 with driving signals in push-pull with each other, in such a way that, when an active switch 180 is turned on, the other is constantly off and vice versa, obtaining a mode? of Push-Pull type operation.

It should be noted here that, although the solution of figure 29 does not provide for the presence of the rectifier 175, if necessary, the rectifier 175 could be inserted in the secondary circuit between the capacitors of resonance 230 and the electric load 110.

? it should be noted that, in all the embodiments illustrated with reference to figures from 16 to 29, the electric load 110 is connected to the first electric branch 205 or to the second electric branch 220, in such a way that said first or second electric branch 205 or 220 is capable of absorbing active electrical energy in virtue? of the electric load 110 connected to it.

This feature, which in many respects is advantageous, can? have the contraindication of reducing the? reactive effect of the resonance inductance 225 or, respectively, of the capacitance? of resonance 230.

Consequently, the tuning of the circuits described in figures 16 to 29 can be more? complex and more dependent on the electric load 110 and its possible variations, with respect to that of the circuits described in figures 7 to 15..

In order to reduce the sensitivity? to the electric load 110 and its variations, in all the aforementioned circuits ? therefore it is possible to introduce further reactive tuning components, or rather further inductances and/or capacities?, which can be placed in series or in parallel with the resonance inductance 225 and/or with the capacity? of resonance 230.

An example ? provided by the solution illustrated in figure 30, in which, purely as an example, the wave generator 145 ? connected simultaneously to two electric loads 110, respectively inductively and capacitively, according to the combination of the diagrams already illustrated in figures 18 and 27.

How can you? understand from the dotted line items, which are all optional, ? for example, is it possible to add a tuning inductance 330 on the first electric branch 205 in series with the resonance inductance 225, and/or add a capacitance? tuning 335 between the central electrical node 215 and a reference voltage (or in parallel with the? Active switch 180), and/or add a tuning inductance 340 and/or a capacitance? of tuning 345 in parallel with the resonance inductance 225.

Further reactive components can also be provided on the secondary circuits, since, being coupled to the primary circuit, they influence its resonance as a function of the coupling parameters.

The function of the additional reactive components, which of course can be used in all circuits described above, is to facilitate the tuning of the circuit to achieve a multiplicity? purposes, such as, for example: making the circuit less sensitive to load variations, maximizing the power transferred to the load, maximizing the efficiency of the circuit to guarantee switching on and off of the switches in zero voltage conditions (Zero Voltage Switching) and/or zero current (Zero Current Switching), reduce the peak voltage on? active switch 180, reduce the average currents in the components, reduce the sensitivity? of the circuit to the tolerances of the components, reduce the sensitivity? of the circuit to the parasitic parameters of the components (for example, if a MOSFET is used as active switch 180, the parasitic capacitance between the drain terminal and the source terminal).

Although the diagram of figure 30 is purely exemplifying, it also demonstrates how all the circuits and solutions described above can be combined with each other, so as to obtain a system 100 capable of simultaneously supplying two or more circuits. electrical loads 110 distinct.

A particularly advantageous embodiment of the wave generator 145 according to the present invention ? illustrated in figure 31 and represents an evolution of the embodiment of figure 23.

While guaranteeing the resonance useful for having ZVS and/or ZCS transitions, the wave generator 145 illustrated in figure 23 ? characterized by rather high electric currents in the resonant inductance 225 and in the active switch 180 which reach their maximum value when the active switch 180 is turned off, i.e. during the transition between the saturation condition (on) and the condition of interdiction (turned off).

In the saturation condition (on), the resistance of the active switch 180 ? almost nil or negligible, from which it follows that the losses in this component are extremely low even for high currents.

The losses P are in fact quantified by the following equation P=R*I<2 >where R ? the resistance and I ? the electric current.

In the interdiction condition (off), the resistance of the active switch 180 ? essentially infinite, but the electric current ? nothing, so that also in this case the losses in the switch are substantially negligible.

On the other hand, in the transition between on and off, there is a variation in the resistance of the active switch 180 in a finite time.

Considering the case of fast active switches, for example N-type MOSFETs, the suitably driven switch goes from on to off in a time of ns, tens of ns or hundreds of ns.

During this finite transient time, the resistance of the active switch 180 increases progressively and, at the same time, the current decreases proportionally, causing a dissipation peak which is not? mitigated by the transition condition ZVS.

To deal with this problem, pu? be used the wave generator 145 illustrated in figure 31, which differs from the one described with reference to figure 23 in that it comprises a further capacitance? of tank 350 having a first terminal connected to the first terminal 185 of the active switch 180 and a second terminal connected to the second terminal 190, for example connected to the same reference voltage.

This ability? of tank 350, connected in parallel to the active switch 180, allows to reduce the losses during the transients mentioned above, since in the instant of switching off of the active switch 180 the capacitance? of tanks 350 ? discharges and forms a low impedance path capable of reducing the current in the active switch 180 and therefore the losses.

However, the capacity of tanks 350 ? often too small to reduce losses significantly.

Therefore, ? preferably the resonant circuit 200 also comprises a further inductance 355 in series with the active switch 180, which has a first terminal connected to the central node 215 and a second terminal connected to the first terminal of the active switch 180, thus resulting connected in series to the parallel formed by the active switch 180 and by the capacitance? of 350 tanks.

In this way, the resonant circuit 200 of the wave generator 145 will comprise substantially a first resonator LC realized by the resonance inductance 225 and by the capacitance? of resonance 230 and a second resonator LC made by? inductance 355 and by the capacitance? of 350 tanks.

These two LC resonators, whose inductances 225 and 355 are both of small value, can be tuned so as to have substantially the same waveform as a ZVS circuit in the ignition phase (therefore zero voltage and low losses in ignition).

At the same time, the two LC resonators can be tuned so as to be out of phase with each other, in order to significantly reduce the current on the switch in the turning off phase, thus to be approached in the shutdown phase to a particularly advantageous ZCS condition, why? low loss.

Most degrees of freedom? of this circuit also guarantees the possibility? to implement many solutions which guarantee ZVS in the switch-on phase of the active switch 180 and ZCS in the switch-off phase, or in any case reduced current with respect to the case of figure 23.

The possible presence of the ability? of tank 350 and of the inductance 355 not ? naturally limited to this embodiment but could be applied to all the circuits described in the present disclosure.

It can be observed that in the solution of figure 31, the electric load 110 ? connected so as to directly receive the voltage wave generated by the wave generator 145 and therefore be supplied substantially with alternating voltage.

However, should it be necessary to supply the electric load 110 with a substantially direct voltage,? it is advantageously possible to insert the rectifier 175 along the second electrical branch 220 upstream of the electrical load 110, so as illustrated in the examples in figure 32.

According to a particularly advantageous variant, the rectifier 175, which ? represented in figure 32 as a generic stage of rectification, pu? be made as shown in figure 33.

In practice, the rectifier 175 pu? comprising a diode 360 having anode connected to the reference voltage and cathode connected to a first terminal of an inductance 365, the second terminal of which ? connected to an electrical node 370 placed on the second electrical branch 220 between the capacitance? of resonance 230 and the electric load 110.

The rectifier 175 pu? also understand a capacity? 375 having a first terminal connected to an electrical node 380, comprised between the diode 360 and the inductance 365, and a second terminal connected to the reference voltage, so as to be in parallel with the diode 360.

The rectifier 175 pu? further comprise an inductance 385 placed along the second electrical branch 220 between the electrical node 370 and the electrical load 110, and possibly a capacitance? 390 having a first terminal referred to the reference voltage and a second terminal connected to an electrical node 395 interposed between the inductance 385 and the electrical load 110.

Alternatively, rectifier 175 diode 360 can be replaced with an active rectification switch 400 (for example a MOSFET), cos? as shown in figure 34.

Both of these embodiments are particularly advantageous since allow to create ZVS and ZCS transitions or, in any case, transitions with low currents and low losses in the diode 360 or, respectively, in the rectifying switch 395.

AND? however, it should be noted that the use of the rectification switch 400 instead of the diode 360 allows you to operate at frequencies lower than the others. high, for example MHz, tens of MHz or hundreds of MHz and typically allows to reduce static losses.

In fact, if we consider the exemplary case of using a MOSFET transistor of the N or GaN type as switch 400, ? possible to have a low channel resistance, which allows to limit losses compared to diodes.

Thanks to the presence of the rectification switch 400, the circuit of figure 34 also allows two different types of driving.

A first piloting, ? the one which involves simulating an ideal diode with the rectification switch 400, ie turning on the rectification switch 400 when the voltage on the drain drops below 0V and turning it off when the voltage rises above 0V.

A second possible driving consists in referring the driving signal of the rectification switch 400 with respect to the driving signal of the active switch 180 of the wave generator 145, with a phase shift between these two driving signals which varies between a minimum value and a maximum, in order to adjust the power transferred to the electrical load 110.

Starting from the diagrams illustrated in figures 31 to 34 ? then is it possible to develop isolated solutions, in which the DC voltage source 105 ? placed in a primary circuit and in which the electric load 110 ? placed in a secondary circuit, which ? galvanically isolated with respect to the primary circuit but ? electrically coupled to it by means of a capacitive coupling system.

For example, in figure 35 ? illustrated a circuit diagram identical to that of figure 32 with the exception of the fact that the capacitance? of resonance 230 ? divided into two capacities? of resonance 230A and 230B, which are placed on the second electric branch 220, respectively between the central electric node 215 of the resonant circuit 200 and the electric load 110, for example upstream of the rectifier 175, and between the electric load 110 and the terminal 235 what? connected to the reference voltage, for example downstream of the rectifier 175.

Even in the isolated case, the rectifier 175 will be able? be possibly made as previously described for the non-isolated case, with the only difference that, as illustrated in figure 35, the second terminal of the rectification switch 400, the second terminal of the capacitances? 375 and 390 (if present) and the second terminal of the load 110 are all referred to an electrical node connected to the second capacitance? of resonance 230B.

Naturally, also in this case, the rectification switch 400 could be replaced by the diode 360, in a similar way to what is illustrated in figure 33.

Starting from the isolated schemes shown above ? Is it possible to develop schemes that are conceptually similar but based on a greater number of phases, for example but not exclusively based on two phases, in order to ensure greater power transmitted to the electric load 110 on equal terms? of tension.

An example of this solution? illustrated in figure 36, in which the system 100 comprises at least two wave generators 145 substantially identical to the one illustrated in figure 31, with the exception of the fact that the capacitances? resonance 230 of these two wave generators 145 are connected to the opposite ends of the single electric load 110, so as to also act as a capacitance? of isolation.

The active switches 180 of the two wave generators 145 can be controlled by respective driving signals, in such a way that they turn on and off with the same frequency but not in phase with each other, i.e. in such a way that the active switches 180 are not always on or off simultaneously but there is always at least a small period of time, within each period of operation, in which an active switch 180 ? turned on while the other switch is active 180 ? off and vice versa.

In this way, by suitably adjusting this period of time, ie the phase shift between the driving signals of the two active switches 180, ? is it advantageously possible to increase the power transmitted to the electric load 110 with parity? of supply voltage, reduce the voltage ripple on the electrical load 110 and/or improve the power factor of the circuit.

If the power level to be transferred to the electric load 110 is particularly high, ? otherwise? It is possible to command the two active switches 180 with driving signals in push-pull with each other, in such a way that, when an active switch 180 is turned on, the other is constantly off and vice versa, obtaining a mode? of Push-Pull type operation.

Also in this case, among the capacities? of resonance 230 and the load 110 pu? possibly be interposed a rectifier 175, which can? be made according to any of the embodiments illustrated above or in any other way.

For example, the rectifier 175 pu? be made according to one of the embodiments illustrated in the Italian patent application No. 102017000139734 filed by the same Applicant, which patent application is understood to be included by reference.

In particular, as illustrated in figure 36, the rectifier 175 can include a first electrical branch 500 adapted to connect a capacitance? of resonance and insulation 230 with a reference node 505, ie referred to a reference voltage, and a second electrical branch 510 able to connect said reference node 505 with the other capacitance? of resonance and isolation 230.

The rectifier 175 also comprises a third electrical branch 515 capable of connecting an intermediate node 520 of the first electrical branch 500 with an intermediate node 525 of the second electrical branch 510.

Two inductances are placed on this third electrical branch 515, of which a first inductance 530 has a terminal connected to the intermediate node 520 and a second inductance 535 has a terminal connected to the intermediate node 252.

The opposite terminals of said two inductances 530 and 535 are mutually connected in a central node 540 of the third electrical branch 515.

Between the central node 540 and the reference node 505 ? connected the electric load 110 and, possibly, a capacitance? 545 connected in parallel to the electric load 110.

The rectifier 175 also comprises two active switches, of which a first active switch 550 arranged on the first electric branch 500, connected between the intermediate node 520 and the reference node 505, and a second active switch 555 arranged on the second electric branch 510, connected between the intermediate node 525 and the reference node.

In detail, each active switch 550 and 555 comprises a first conduction terminal connected to the reference node 505 and a second conduction terminal connected to the respective intermediate node 520 or 525.

In addition, each active switch 550 and 555 includes a control terminal coupled to a control module (not shown) for receiving a respective drive signal.

Possibly, on the first electrical branch 500, between the intermediate node 520 and the reference node 505, can? be present a further inductance 560 connected in series to the active switch 550 and/or a capacitance? of bridge 565 connected in parallel to the active switch 550.

Similarly, on the second electrical branch 510, between the intermediate node 525 and the reference node 505, it can is there a further inductance 570 connected in series to the active switch 555 and/or a capacitance? of bridge 575 connected in parallel to the active switch 555.

In operation, the two active switches 550 and 555 can be switched on and off alternately, in order to rectify respective half-waves of the voltage wave applied between the capacitors? 230.

For example, each of the two active switches 550 and 555 can? be driven so as to simulate an ideal diode, ie turning it on when the voltage in the respective intermediate node 520 and 525 drops below 0V and turning it off when the voltage rises above 0V.

In this way, the rectifier 175 can? be configured to rectify the? input voltage wave with mode? similar to those of a double half-wave rectifier based on a center tap transformer, but without the need? of a transformer element, with capacity? particularly efficient synchronous rectification system even at very high frequencies and therefore with a reduction in overall dimensions, costs and energy dissipation.

Naturally this type of rectifier 175 ? only a non-limiting example which, however, is not ? applicable only to the system according to the scheme of Figure 36 but could be applied to all other embodiments in the present discussion.

There? premised, it is observed that in the isolated embodiments illustrated in figures 35 and 36, the two capacities? of resonance/isolation can be capacity? discrete, i.e. inseparable components comprising a first terminal connected to the primary circuit and a second terminal connected to the secondary circuit, so as to create a single and inseparable device, such as for example an isolated electric power supply.

In other embodiments, each capability? resonance/insulation could however be achieved by a pair of mutually separable plates, of which a transmit plate connected to the primary circuit and a receive plate connected to the secondary circuit.

In this way, the primary circuit, including the DC voltage source 105, the wave generator 145 and the transmission plates, can be installed in a first device, while the secondary circuit, comprising at least the electric load 110, the rectifier 175 and the receiving plates, can? be installed on a second device, physically separate and movable (movable) from the first device.

For example, the first device could be configured as a charging cradle while the second device could be a charging or powering device, such as a smartphone, laptop, TV, and more.

In this way, suitably approaching the second device to the first device ? Is it possible to approach and face each transmission frame to a corresponding receiving frame, reconstituting the capacities? of resonance/isolation that make cos? a wireless transmission system of electrical power via capacitance.

In an alternate sizing of the circuits illustrated in FIGS. 31 to 36, the resonant inductors 225 and 385 have inductive values much greater than higher than the inductors 355 and 365, so as to have all the previously illustrated advantages and only two very small inductors 355 and 365 crossed by currents characterized by large variations over time (high ratio between RMS current and average current), while the inductors 225 and 385 can be more? large, in order to limit the average current in all the components acting as current generators, and characterized by low ripple.

This type of sizing guarantees, for example, the use of small air-wound inductors for inductors 355 and 365, characterized by high current oscillations at high frequency, and inductors wound on a ferromagnetic core for inductors 225 and 385, characterized by low current ripple useful to limit losses in the core.

Alternatively, all inductors can be wound in air, as long as? the operating frequency is high enough to allow sizing characterized by small inductance values (tens or hundreds of nH).

Obviously to everything described a technician of the sector will be able? make numerous modifications of a technical-application nature, without thereby departing from the scope of the invention as claimed below.

Claims (9)

1. A system (100) for transferring electrical power to an electrical load (110), comprising: - a source of direct electric voltage (105), ed - at least one wave generator (145) able to convert the direct electric voltage into voltage waves to be transmitted to the electric load (110), said wave generator (145) comprising a first input terminal (150) and a second input terminal input (155), which are connected to the direct electric voltage source (105) so as to be subjected to a substantially constant voltage difference supplied by the direct electric voltage source (105) itself, wherein said wave generator (145) comprises at least: - an active switch (180) provided with two connection terminals (185, 190) and able to be controlled by an electric pilot signal between a saturation condition, in which it allows the passage of electric current between said connection terminals (185 , 190), and an interdiction condition, in which it prevents said passage of electric current, and - a resonant circuit (200) tuned to reduce the electric power applied to said active switch (180) in the instants in which said active switch switches from saturation condition to interdiction condition and vice versa, wherein said resonant circuit (200) comprises at least: - a central electrical node (215) to which ? connected a first connection terminal (185) of the active switch (180), the second connection terminal (190) of the active switch (180) being connected to the second input terminal (155), - a first electrical branch (205) extending between said central electrical node (215) and the first input terminal (150), - a second electrical branch (220) extending between said central electrical node (215) and the first input terminal (150) or between said central electrical node (215) and a further terminal (235) connected to a reference voltage, - a resonance inductance (225) placed on the first electric branch (205), and - a capacitance? of resonance (230) placed on the second electric branch (220) in which the electric load (110) ? placed in a secondary circuit, which ? galvanically isolated from the first electrical branch (205) to which ? electrically connected by inductive coupling. 2. A system (100) according to claim 1, wherein said inductive coupling comprises the resonant inductance (225) and a coupling inductance (300) located in the secondary circuit and suitable for inductive coupling with the resonant inductance ( 225). 3. A system (100) according to claim 2, wherein said inductive coupling comprises a transformer provided with a magnetic core on which wound a primary winding, which forms at least partially the resonant inductance (225), and a secondary winding, which forms at least partially the coupling inductance (300). A system (100) according to claim 2, wherein the inductive coupling comprises a wireless transmit coil, which forms at least partially the resonant inductance (225), and a wireless receive coil, which forms at least partially the ?coupling inductance (300). 5. A system (100) according to any one of the preceding claims, comprising at least two of said wave generators (145), which are configured to transmit phase-shifted voltage waves to the electric load. 6. A system (100) according to any one of the preceding claims, comprising a rectifier (175) adapted to receive the voltage wave generated by the wave generator (145), to convert said voltage wave into a rectified voltage and to apply said rectified voltage to the electrical load (110). 7. A system (100) according to any one of the preceding claims, wherein the direct voltage source (105) comprises a rectifier adapted to receive an alternating voltage at the input and to convert said alternating voltage into direct voltage. 8. A system (100) according to any one of the preceding claims, wherein said resonant circuit (200) comprises a capacitance? of tank (350) connected in parallel to the active switch (180). A system (100) according to claim 8, wherein the resonant circuit (200) comprises an inductance (355) placed in series between the central electrical node (215) and the active switch (180).