Electrical energy conversion system with piezoelectric assembly(s) and electrical transformer

Abstract

Electrical energy conversion system with piezoelectric assembly(s) and electrical transformer This electrical energy conversion system (5) comprises: - a converter (10) comprising E first switching assembly(s) (30), each associated with an input voltage and comprising two first switches (36); N second switching assembly(s) (40), each associated with an output voltage and comprising two second switches (46); and at least one piezoelectric assembly (12) connected to a switch; E≥1, N≥1; - a control device (20) configured to control, during a resonance cycle, a switching of the switches to alternate constant voltage phases and constant charge phases at the terminals of said piezoelectric assembly(s).The converter (10) comprises an electrical transformer (80) having a primary winding (82) connected to a first switching assembly and a secondary winding (84) connected to a second switching assembly, and each piezoelectric assembly is connected between a switch and a winding. Figure for abstract: Figure 1.

Description

Title of the invention: Electrical energy conversion system with piezoelectric assembly(s) and electrical transformer

[0001] The present invention relates to an electronic electrical energy conversion system capable of converting one or more input voltages into one or more output voltages, the conversion system comprising an electrical energy converter configured to deliver N distinct output voltage(s), from E distinct input voltage(s), E and N each being an integer greater than or equal to 1, the converter comprising E first switching assembly(s), each being associated with a respective input voltage and comprising at least two first switches, each first switch being connected to a terminal for applying the respective input voltage; N second switching assembly(s), each being associated with a respective output voltage and comprising at least two second switches, each second switch being connected to a terminal for supplying the respective output voltage;and at least one piezoelectric assembly, each connected to one of the first and second switches, and comprising at least one piezoelectric element.;

[0002] The conversion system also comprises an electronic device for controlling the electrical energy converter, the electronic control device being configured to control, during a respective resonance cycle of the piezoelectric assembly(s), a switching of each of the first and second switches to alternate phases at substantially constant voltage across the terminals of the piezoelectric assembly(s) and phases at substantially constant charge across the terminals of said piezoelectric assembly(s).

[0003] The invention relates to the field of electronic electrical energy conversion systems, in particular those comprising a piezoelectric element, in particular systems for conversion into continuous electrical energy, i.e. direct-direct conversion systems, also called DC-DC conversion systems (from the English Direct Current - Direct Current), and alternating-direct conversion systems, also called AC-DC conversion systems (from the English Alternating Current - Direct Current).

[0004] Documents FR 3 086 471 Al and FR 3 086 472 Al, as well as the thesis manuscript “Piezoelectric DC-DC converters with temporary energy storage in mechanical form” by Benjamin POLLET, disclose an electrical energy converter of the aforementioned type, visible in figure 20 of documents FR 3 086 471 Al and FR 3 086 472 Al, and in [Fig.4]. 15 of the aforementioned thesis manuscript.

[0005] The switches of the first and second switching bridges are controlled cyclically, at the main oscillation frequency of the piezoelectric assemblies around their preselected resonance mode with, between each closure of the switch(es), a phase in which the piezoelectric assemblies are in open circuit via the opening of at least one switch. The closing of each switch is advantageously carried out under an approximately zero voltage at its terminals, and in all cases, the closing of a switch never causes a significant variation in voltage at the terminals of the piezoelectric assemblies (less than 20%, and advantageously less than 10%, of the input voltage Vin or of the output voltage Vout).

[0006] In steady state, a control cycle typically comprises six successive distinct phases, namely three phases at substantially constant voltage across each piezoelectric element and three phases at substantially constant charge across said piezoelectric element, with alternation between phases at substantially constant voltage and phases at substantially constant charge.

[0007] As indicated in document FR 3 086 471 A1 or in the thesis manuscript, an advantage of using two piezoelectric elements is that the output voltage is thus isolated from the input voltage, without it being necessary to use a transformer.

[0008] The isolation is capacitive and is therefore not achieved with a transformer which is a source of losses, but by the fact that the impedance of the piezoelectric resonator is very high at low frequency and blocks any propagation of low-frequency voltage from the input to the output and vice versa, in particular the possible common mode component equal to half the sum of the potentials at the output voltage supply terminals minus half the sum of the potentials at the input voltage application terminals. Indeed, each piezoelectric element is modeled in the form of a capacitor and a resonant branch connected in parallel to the capacitor, the capacitance of said capacitor being called parallel capacitance, or reference capacitance, and noted Co.A low frequency signal of type 50 / 60 Hz will then be filtered by the high impedance (for example 3.1 MQ for Co = 1 nF at 50 Hz) of each of the blocked capacitors of the two piezoelectric resonators, thus creating isolation between the input and output parts of the converter.

[0009] This advantage is present even compared to a piezoelectric transformer, in which all the energy supplied to the primary is not completely transmitted to the secondary and the primary must also set in motion a greater mass, namely that of the primary plus that of the secondary, which generates losses.

[0010] However, the operation of such a converter is not optimal.

[0011] The aim of the invention is then to propose a conversion system comprising a electrical energy converter with at least one piezoelectric assembly, and a device for controlling the electrical energy converter, the system allowing better operation of the converter.

[0012] To this end, the invention relates to an electronic electrical energy conversion system capable of converting one or more input voltages into one or more output voltages, the conversion system comprising:

[0013] - an electrical energy converter configured to deliver N output voltage(s) distinct, from E distinct input voltage(s), E and N each being an integer greater than or equal to 1, the converter comprising:

[0014] + E first switching set(s), each being associated with a voltage respective input and comprising at least two first switches, each first switch being connected to a terminal for applying the respective input voltage;

[0015] + N second switching set(s), each being associated with a voltage of respective output and comprising at least two second switches, each second switch being connected to a terminal for supplying the respective output voltage;

[0016] + at least one piezoelectric assembly, each being connected to a switch among the first and second switches, and comprising at least one piezoelectric element;

[0017] - an electronic device for controlling the electrical energy converter, the electronic control device being configured to control, during a respective resonance cycle of the piezoelectric assembly(s), a switching of each of the first and second switches to alternate phases at substantially constant voltage across the terminals of the piezoelectric assembly(s) and phases at substantially constant charge across said piezoelectric assembly(s),

[0018] the converter further comprising an electrical transformer comprising at least one primary winding and at least one secondary winding, each primary winding being connected to a first switching assembly, each secondary winding being connected to a second switching assembly, and each piezoelectric assembly is connected between a respective switch and winding.

[0019] With the energy conversion system according to the invention, the electrical transformer allows much higher conversion ratios than with the conversion system of the state of the art, due to the transformation ratio between the secondary and primary windings, the value of the voltage during at least one phase at substantially constant voltage at the terminals of the piezoelectric assembly(s), i.e. the value of at least one voltage level, then depending on a voltage of respective output multiplied by this transformation ratio.

[0020] The electrical transformer associated with the piezoelectric assembly(s) also makes it possible to ensure several successive levels of insulation, and for example to offer better insulation for critical systems.

[0021] Those skilled in the art will further observe that there is a complementarity between these two insulations. In the event of a faulty control or switch, at the primary or secondary, the primary or secondary winding of the electrical transformer could be on the path of a short circuit, but thanks to the piezoelectric assembly(s) which block the low-frequency components, this short circuit is naturally open, which prevents the electrical transformer from heating up and a failure of the latter which could also cause electrical risks for the user.

[0022] Furthermore, the use of two different types of insulation reinforces the insulation and safety, in the sense that two faults of a different nature would be required to cause a risk of loss of insulation, which is less likely than two faults of the same nature which could appear at the same time following the same type of stress (T°, humidity, etc.).

[0023] In addition, the addition of piezoelectric insulation is likely to make it possible to alleviate constraints weighing on the electrical transformer, such as the distance between primary and secondary turns, or even the thickness of the varnish; and thus gain in cost and / or efficiency.

[0024] Preferably, the arrangement of at least one piezoelectric assembly upstream of the electrical transformer makes it possible to reduce, or even eliminate, the possible DC component at the terminals of the primary winding of the electrical transformer, and thus to further improve its operation.

[0025] Those skilled in the art will observe that an electrical transformer alone, without being combined with one or more piezoelectric assemblies, only allows a fixed voltage ratio to be made between the input and the output. To be able to freely adjust the output voltage, it is possible to add an inductive element (LLC converter type, dual bridge).

[0026] Nevertheless, the conversion system according to the invention combining with the electrical transformer at least one piezoelectric assembly offers the advantage of having fewer losses (higher quality factor) and of being more compact (greater storable energy density per unit of volume) and also of being able to support a continuous voltage component.

[0027] According to other advantageous aspects of the invention, the electronic energy conversion system comprises one or more of the following characteristics, taken individually or in all technically possible combinations:

[0028] - each piezoelectric assembly is connected between a first switch and a primary winding or between a second switch and a secondary winding;

[0029] - each winding is connected to at least one piezoelectric assembly or has between its ends a voltage of substantially zero average value over a respective resonance cycle, the control device then being configured to control the switches of the switching assembly connected to said winding so as to obtain said voltage of substantially zero average value;

[0030] - the converter comprises several piezoelectric assemblies, and each bearing is connected to at least one piezoelectric assembly;

[0031] - the converter comprises a single piezoelectric assembly connected to a respective bearing, and the or each other winding has between its ends a voltage of substantially zero average value over a respective resonance cycle;

[0032] - at least a first switching assembly is in the form of a first bridge of switching comprising at least one first switching branch, each first switching branch being connected between two terminals for applying a respective input voltage and comprising at least two first switches connected in series and connected together at a first midpoint;

[0033] each first switching assembly preferably being in the form of a respective first switching bridge;

[0034] - at least one first switching assembly comprises two first branches switching;

[0035] each first switching assembly preferably comprising two first switching branches;

[0036] - a piezoelectric assembly is connected between a first midpoint and a respective primary bearing;

[0037] - at least one second switching assembly is in the form of a second bridge switching comprising at least one second switching branch, each second switching branch being connected between two terminals for supplying a respective output voltage and comprising at least two second switches connected in series and connected together at a second midpoint;

[0038] each second switching assembly preferably being in the form of a respective second switching bridge;

[0039] - at least one second switching assembly comprises two second switching branches;

[0040] each second switching assembly preferably comprising two second switching branches;

[0041] - a piezoelectric assembly is connected between a second midpoint and a respective secondary bearing;

[0042] - a winding comprises, between its ends, at least one intermediate point connected to a respective switching assembly or to a respective input voltage application or output voltage supply terminal;

[0043] - the converter comprises a pair of piezoelectric assemblies connected to a same respective winding, and further a complementary switch connected directly between ends of said pair of piezoelectric assemblies, said ends connected directly to each other via the complementary switch being connected to a same respective switching assembly;

[0044] - the converter comprises a pair of piezoelectric assemblies connected to a same respective winding, and further a switching assistance circuit connected between ends of said pair of piezoelectric assemblies, said ends connected together via the switching assistance circuit being connected to a same respective switching assembly, the switching assistance circuit being configured to, via the circulation of a previously received current, discharge a parasitic capacitance of at least one switch of the respective switching assembly to which it is connected, and respectively charge at least one parasitic capacitance of another switch of said switching assembly;

[0045] - the switching assistance circuit comprises an element chosen from the group consisting of: an inductor; a first assembly formed of an inductor and a diode connected in series; a second assembly formed of an inductor and a capacitor connected in series; and an additional piezoelectric element;

[0046] the switching assistance circuit preferably being constituted by an element chosen from said group;

[0047] the inductance being preferably still in the form of a parasitic inductance of the respective winding to which the pair of piezoelectric assemblies is connected;

[0048] - the electrical transformer is an air transformer or a ma transformer magnetic, the magnetic transformer further comprising a magnetic core, each winding then being arranged around the core;

[0049] the electrical transformer being for example an autotransformer;

[0050] - the electrical energy converter is configured to deliver several voltages separate outputs and comprises several second switching sets, N being an integer greater than or equal to 2; and

[0051] - the electrical energy converter is configured to convert several voltages distinct inputs and has several first switching sets, E being an integer greater than or equal to 2.

[0052] These characteristics and advantages of the invention will appear more clearly on reading the description which follows, given solely by way of non-limiting example, and made with reference to the appended drawings, in which:

[0053] [Fig.l] [Fig.l] is a schematic representation of an electronic electrical energy conversion system according to the invention, comprising an electrical energy converter and an electronic device for controlling said converter, the converter being configured to deliver N output voltage(s) from E input voltage(s), and comprising E first switching assembly(s), each being associated with a respective input voltage and comprising at least two first switches, each first switch being connected to a terminal for applying the respective input voltage; N second switching assembly(s), each being associated with a respective output voltage and comprising at least two second switches, each second switch being connected to a terminal for supplying the respective output voltage;at least one piezoelectric assembly, each connected to one of the first and second switches; and further an electrical transformer having at least one primary winding and at least one secondary winding, each primary winding connected to a first switching assembly, each secondary winding connected to a second switching assembly, and each piezoelectric assembly connected between a respective switch and winding; ;

[0054] E and N being here each equal to 1, the first switching assembly being in the form of a first bridge with two first branches each comprising two first switches, the second switching assembly being in the form of a second bridge with two second branches each comprising two second switches, and the converter comprising four piezoelectric assemblies, each being connected to a midpoint of a respective branch;

[0055] [Fig.2] [Fig.2] is a view similar to that of [Fig.l], with two piezoelectric assemblies, each being connected to a midpoint of a respective first branch;

[0056] [Fig.3] [Fig.3] is a view similar to that of [Fig.l], with a single piezoelectric assembly connected to a midpoint of a respective first branch;

[0057] [Fig.4] [Fig.4] is a view similar to that of [Fig.l], with four piezoelectric assemblies, where the first switching assembly comprises a single first branch with two first switches, and with at the primary a piezoelectric assembly then connected to the midpoint of the first branch, and the other piezoelectric assembly connected to a respective terminal for applying the input voltage;

[0058] [Fig.5] [Fig.5] is a view similar to that of [Fig.4], with two piezoelectric assemblies, one piezoelectric assembly being connected to the midpoint of the first branch, and the other piezoelectric assembly being connected to a midpoint of a respective second branch;

[0059] [Fig.6] [Fig.6] is a view similar to that of [Fig.4], with a single set piezoelectric, connected to the midpoint of the first branch;

[0060] [Fig.7] [Fig.7] is a view similar to that of [Fig.l], with two piezoelectric assemblies, where the first switching assembly comprises a single first branch with two first switches, and the second switching assembly comprises a single second branch with two second switches; one piezoelectric assembly being connected to the midpoint of the first branch, and the other piezoelectric assembly being connected to a respective terminal for supplying the output voltage;

[0061] [Fig.8] [Fig.8] is a view similar to that of [Fig.7], with one piezoelectric assembly connected to the midpoint of the first branch, and the other piezoelectric assembly connected to the midpoint of the second branch;

[0062] [Fig.9] [Fig.9] is a view similar to that of [Fig.8], with a single piezoelectric assembly, connected to a respective terminal for applying the input voltage, and where the secondary winding comprises, between its ends, an intermediate point connected to a respective terminal for supplying the output voltage;

[0063] [Fig. 10] [Fig. 10] is a view similar to that of [Fig.9], where E is equal to 1 and N is equal to 3; where the secondary winding has, between its ends, three intermediate points each connected to a respective terminal for supplying a respective output voltage or to a respective second switching assembly;

[0064] [Fig. 11] [Fig. 11] is a view analogous to that of [Fig.l], where E is equal to 2 and N is equal to 1; with two piezoelectric assemblies, one piezoelectric assembly being connected to the midpoint of a respective first branch associated with one of the input voltages, and the other piezoelectric assembly being connected to a midpoint of a respective second branch;

[0065] [Fig.12] [Fig.12] is a view analogous to that of [Fig.l], where E is equal to 1 and N is equal to 2; with two piezoelectric assemblies, each being connected to a midpoint of a respective second branch;

[0066] [Fig. 13] [Fig. 13] is a view similar to that of [Fig.2], according to a complementary aspect where the converter further comprises a switching assistance circuit connected between the midpoints of the first branches, i.e. between the ends of the two piezoelectric assemblies which are not connected to the primary winding;

[0067] [Fig. 14] [Fig. 14] is a schematic representation of different types of switching aid circuit; and

[0068] [Fig. 15] [Fig. 15] is a view similar to that of [Fig.2], according to a complementary aspect where the converter further comprises a complementary switch connected directly between the midpoints of the first branches, i.e. between the ends of the two piezoelectric assemblies which are not connected to the primary winding.

[0069] The expression “substantially equal to” defines a relationship of equality to plus or minus 10%, preferably to plus or minus 5%.

[0070] In [Fig.l], an electronic electrical energy conversion system 5 comprises an electrical energy converter 10 comprising at least one piezoelectric assembly 12 of at least one piezoelectric element 15, several switches K i, K2, K3, K4, K5, K6, K7, K8 capable of being controlled to alternate phases at substantially constant voltage across the terminals of the piezoelectric assembly(s) 12 and phases at substantially constant charge across the terminals of the piezoelectric assembly(s) 12; and an electronic device 20 for controlling the electrical energy converter 10. Each piezoelectric assembly 12 comprises a first end 16 and a second end 18.

[0071] For the sake of simplification of the drawings, the rectangle schematically delimiting the electrical energy converter 10 and the electronic control device 20 are shown only in [Fig. 1], and only the contents of the converter 10 are then shown in Figures 2 to 13 and 15.

[0072] The electronic electrical energy conversion system 5 is typically a system for converting into direct electrical energy, such as a direct-direct conversion system capable of converting a first direct electrical energy or voltage received at the input into a second direct electrical energy or voltage delivered at the output, or even an alternating-direct conversion system capable of converting an alternating electrical energy or voltage received at the input into a direct electrical energy or voltage delivered at the output of the conversion system 5.

[0073] When the electrical energy conversion system 5 is an AC-DC conversion system, the electrical energy conversion system 5 preferably further comprises a voltage rectifier, not shown, connected to the input of the electrical energy converter 10 and capable of rectifying the AC electrical voltage received at the input of the conversion system 5 to deliver a rectified electrical voltage at the input of the converter 10, the electrical energy converter 10 preferably being a DC-DC converter capable of converting DC electrical energy or voltage into another DC electrical energy or voltage. The voltage rectifier is for example a rectifier bridge, such as a diode bridge. Alternatively, the voltage rectifier is formed in part by switches of the converter 10.A continuous electrical voltage means a voltage that varies slowly with respect to the rate of variation of the voltage across the piezoelectric assemblies. These are voltage variations that typically evolve at a frequency at least 10 times lower than the mechanical oscillation frequency of the piezoelectric assemblies 12. .

[0074] Those skilled in the art will observe that these different examples for the system conversion 5, whether it is a DC-DC conversion system or an AC-DC conversion system, are also presented in documents FR 3 086 471 Al and FR 3 086 472 Al, in particular with regard to their figures 1 and 2.

[0075] The electrical energy converter 10 is preferably a DC-DC converter, and is also called a DC-DC converter. The DC-DC converter generally has the role of regulating a supply voltage of a load 22 to a stable value, by being powered by an energy source 24 providing a substantially DC voltage. The energy source 24 is for example a battery or a solar panel.

[0076] The electrical energy converter 10 is then configured to raise the value of the DC voltage between its input and its output, and is then also called a DC-DC step-up converter; or is configured to lower the value of the DC voltage between its input and its output, and is then called a DC-DC step-down converter.

[0077] The electrical energy converter 10 is configured to deliver N distinct output voltage(s), from E distinct input voltage(s), E and N each being an integer greater than or equal to 1.

[0078] In the examples of figures 1 to 9, 13 and 15, the electrical energy converter 10 is configured to deliver an output voltage, denoted Vout, from an input voltage, denoted Vin, the number E of input voltage(s) and the number N of output voltage(s) then each being equal to 1.

[0079] In the examples of Figures 10 and 12, the electrical energy converter 10 is configured to deliver several distinct output voltages, denoted Voutj where j is an integer index between 1 and N, from the input voltage Vin, the number N of distinct output voltages then being greater than 1, in particular equal to 3 in the example of [Fig. 10] and to 2 in that of [Fig. 12]. According to this example, the converter 10 is typically connected to several loads 22, as shown in Figures 10 and 12.

[0080] In the example of [Fig. 11], the electrical energy converter 10 is configured to deliver an output voltage, denoted Vout, from several distinct input voltages, denoted Vink where k is an integer index between 1 and E, the number E of distinct input voltages then being greater than 1, in particular equal to 2 in the example of [Fig. 11]. According to this example, the converter 10 is typically connected to several sources 24, as shown in [Fig. 11].

[0081] The electrical energy converter 10 comprises one or more piezoelectric assemblies 12 each formed of one or more piezoelectric elements 15, and the control device 20 is configured to operate the piezoelectric material of the piezoelectric elements 15 at their resonance in order to exploit charge transfer phases making it possible to dispense with the use of an inductive element, while regulating the output voltage by maintaining the resonance of the piezoelectric material, i.e. with repeated switching cycles at an operating frequency dependent on the resonance frequency of the piezoelectric elements 15, and by adjusting the durations between the respective switchings within the resonance cycle.

[0082] In steady state, the piezoelectric assembly(s) 12 exchange a charge and a substantially zero power over a resonance cycle, apart from losses. In other words, each piezoelectric assembly 12 gives back, substantially as much as it receives, energy and charge over a period. Two operating conditions then apply to the permanent / steady state, namely charge balance and energy balance over a resonance period. Even if during transients (start-up, variation of voltage steps, change of output current) this balance is not respected, it must nevertheless be possible to achieve it in steady state. This requires in particular a certain arrangement of the voltage steps during the resonance period.For example, for three-voltage-step operation, the two extreme voltage steps are controlled during one half-period of a given polarity of a current IL flowing in the piezoelectric elements 15, and the intermediate voltage step is controlled during the other half-period of opposite polarity of the current IL flowing in the piezoelectric elements 15.

[0083] As known per se, the mechanical oscillation of the piezoelectric elements 15 is approximately sinusoidal. The total mechanical deformation of the piezoelectric elements 15 is the sum of elementary mechanical deformations of each of the piezoelectric elements 15.

[0084] An increase or a decrease in the energy stored over a period leads respectively to an increase or a decrease in the oscillation amplitude. Furthermore, during a phase with a substantially constant charge at the terminals of the piezoelectric assemblies 12, that is to say when the piezoelectric elements 15 are placed in a substantially open electrical circuit, with a low exchange of electrical charges between the piezoelectric elements 15 and the outside, an increase in the amplitude of the oscillations causes an increase in the speed of variation of the voltage Vp at the terminals of the piezoelectric assemblies 12, and during a phase with a substantially constant voltage at the terminals of the piezoelectric assemblies 12, this increase in oscillation amplitude leads to an increase in the current IL flowing in the piezoelectric elements 15.

[0085] By substantially constant charge is meant an exchange of a charge with the outside which is less than 10% of the charge which would have been exchanged with the outside if the voltage had been kept constant. In other words, by substantially constant charge constant means a charge variation less than 10% of the charge which would have been exchanged with the exterior of the piezoelectric assemblies 12 if the voltage across the terminals of the piezoelectric assemblies 12 had been kept constant over the time period considered.

[0086] By substantially open electrical circuit is meant a circuit in which a possible leakage current leads to a variation in charge of the piezoelectric assemblies 12 of less than 10% of the charge which would have been exchanged with the exterior of the piezoelectric assemblies 12 if the voltage across the terminals of the piezoelectric assemblies 12 had been kept constant over the time period considered.

[0087] By substantially constant voltage is meant a voltage variation of less than 20%, preferably less than 10%, of the input or output voltage of the converter 10. For example, if the input voltage of the converter 10 is equal to 100V, then the voltage variation during each phase at substantially constant voltage, i.e. on each step at substantially constant voltage, is less than 20% of this voltage, i.e. less than 20V; preferably less than 10% of this voltage, i.e. less than 10V. Each phase at substantially constant voltage is also called a voltage step.

[0088] The converter 10 then comprises several switches Kb K2, K3, K4, K5, K6, K7, K8 visible at least in part in FIGS. 1 to 9, 13 and 15, Ki>m visible in FIGS. 10 to 12 (where i is an integer index representing a switch identifier, typically between 1 and 8 in the examples of FIGS. 10 to 12, and m is an integer index representing an input voltage identifier, or respectively an output voltage identifier, typically between 1 and 3 in the examples of FIGS. 10 to 12) capable of being controlled to alternate phases at substantially constant voltage and phases at substantially constant load at the terminals of the piezoelectric assemblies 12, within periods of substantially constant duration corresponding to the operating frequency of the converter 10, depending on the resonance frequency, also called natural frequency, of the piezoelectric elements 15.The phases at substantially constant load allow, in steady or permanent mode, to pass from one constant voltage to another and to close the switches which must be closed when the voltage at their terminals is preferably zero in order to have a so-called zero voltage switching, also called ZVS mode switching (from the English Zero Voltage Switching).

[0089] The converter 10 comprises E first switching assembly(s) 30, each being associated with a respective input voltage Vin, Vin_k and comprising at least two first switches 36, each first switch 36 being connected to a terminal 34 for applying the respective input voltage Vin, Vin_k, where E is the number of distinct input voltage(s) Vin, Vin_k, E being greater than or equal to 1.

[0090] In the examples of figures 1 to 13 and 15, the first switches 36 correspond to the switches K5, K6, K7, K8 visible at least in part in figures 1 to 9, 13 and 15, or to the switches Ki>m visible in figures 10 to 12, with i between 5 and 8.

[0091] In the examples of figures 1 to 10, 12, 13 and 15, where E is equal to 1, the converter 10 comprises a single first switching assembly 30 associated with the input voltage Vin.

[0092] In the example of [Fig. 11], where E is equal to 2, the converter 10 comprises two first switching assemblies 30, each being associated with a respective input voltage Vinl, Vin_2.

[0093] As an optional addition, at least one first switching assembly 30 is in the form of a first switching bridge comprising at least one first switching branch 32, each first switching branch 32 being connected between two terminals 34 for applying a respective input voltage Vin, Vin_k and comprising at least two first switches 36 connected in series and connected together at a first midpoint 38. Each first switching branch 32 is preferably made up of the first two switches 36.

[0094] According to this optional addition, each first switching assembly 30 is preferably in the form of a respective first switching bridge, and then comprises at least one first switching branch 32.

[0095] As a further optional addition, at least one first switching assembly 30 comprises two first switching branches 32. According to this optional addition, each first switching assembly 30 preferably comprises two first switching branches 32.

[0096] In the examples of Figures 1 to 3, 11 to 13 and 15, the or each first switching assembly 30 comprises two first switching branches 32. In the examples of Figures 1 to 3, 11 to 13 and 15, the or each first switching assembly 30 is preferably made up of the two first switching branches 32.

[0097] In the examples of figures 1 to 3, 12, 13 and 15, the first two switches 36 are denoted K5, K6 for one of the first two switching branches 32, and respectively K7, K8 for the other of the first two switching branches 32. In the example of [Fig. 11], the first two switches 36 are denoted K5>k, K6>k for one of the first two switching branches 32, and respectively K7jk, K8jk for the other of the first two switching branches 32, where k is the integer index for the input voltage, between 1 and E.

[0098] In the examples of Figures 4 to 10, the first switching assembly 30 comprises a single first switching branch 32. In the examples of Figures 4 to 10, the first switching assembly 30 is preferably made up of a single first switching branch 32. In these examples, the first two switches 36 are denoted K5, K6 for the single first switching branch 32.

[0099] Among the two application terminals 34 of the input voltage Vin, one has a lower potential, noted Vinn, and the other has a higher potential, noted Vinp.

[0100] When the electrical energy converter 10 is configured to receive several distinct input voltages Vin k, such as in the example of [Fig. 11], it comprises, for each respective input voltage Vin k, a respective first switching assembly 30. In this example of [Fig. 11], the lower potentials of the input voltages Vin_i, Vin 2 are respectively denoted Vinni, Vinn?, and the higher potentials of the input voltages Vin_i, Vin 2 are respectively denoted Vinpi, Vinp2.

[0101] The converter 10 comprises N second switching assembly(s) 40, each being associated with a respective output voltage Vout, Voutj and comprising at least two second switches 46, each second switch 46 being connected to a terminal 44 for supplying the respective output voltage Vout, Voutj, where N is the number of distinct output voltage(s) Vout, Voutj, N being greater than or equal to 1.

[0102] In the examples of figures 1 to 13 and 15, the second switches 46 correspond to the switches Kb K2, K3, K4 visible at least in part in figures 1 to 9, 13 and 15, or to the switches Ki>m visible in figures 10 to 12, with i between 1 and 4.

[0103] In the examples of figures 1 to 9, 11, 13 and 15, where N is equal to 1, the converter 10 comprises a single second switching assembly 40 associated with the output voltage Vout.

[0104] In the example of [Fig. 10], where N is equal to 3, the converter 10 comprises three second switching assemblies 40, each being associated with a respective output voltage Vout_i, Vout 2, Vout 3; and in the example of [Fig. 12], where N is equal to 2, the converter 10 comprises two second switching assemblies 40, each being associated with a respective output voltage Vout_i, Vout_2.

[0105] As an optional addition, at least one second switching assembly 40 is in the form of a second switching bridge comprising at least one second switching branch 42, each second switching branch 42 being connected between two terminals 44 for supplying a respective output voltage Vout, V outj and comprising at least two second switches 46 connected in series and connected together at a second midpoint 48. Each second switching branch 32 is preferably made up of the two second switches 46.

[0106] According to this optional addition, each second switching assembly 40 is preferably in the form of a respective second switching bridge, and then comprises at least one second switching branch 42.

[0107] As a further optional addition, at least one second switching assembly 40 comprises two second switching branches 42. According to this optional addition, each second switching assembly 40 preferably comprises two second switching branches 42.

[0108] In the examples of Figures 1 to 6, 11 to 13 and 15, the or each second switching assembly 40 comprises two second switching branches 42. In the examples of Figures 1 to 6, 11 to 13 and 15, the or each second switching assembly 40 is preferably made up of the two second switching branches 42.

[0109] In the examples of figures 1 to 6, 11, 13 and 15, the two second switches 46 are denoted Kb K2 for one of the two second switching branches 42, and respectively K3, K4 for the other of the two second switching branches 42. In the example of [Fig.12], the two second switches 46 are denoted Kij, K2jj for one of the two second switching branches 42, and respectively K3jj, K4j for the other of the two second switching branches 42, where j is the integer index for the output voltage, between 1 and N.

[0110] In the examples of figures 7 and 8, the second switching assembly 40 comprises a single second switching branch 42. In the examples of figures 7 and 8, the second switching assembly 40 is preferably made up of a single second switching branch 42. In the example of [Fig.8], the two second switches 46 are denoted Kb K2 for the single second switching branch 42. In the example of [Fig.7], the two second switches 46 are denoted K3, K4 for the single second switching branch 42.

[0111] In the example of [Fig.9], the second switching assembly 40 comprises two second switches 46 connected to the same output voltage supply terminal 44. In this example, the two second switches 46 are denoted Kh K3

[0112] In the example of [Fig. 10], the converter 10 comprises three second switching assemblies 40, among which two second switching assemblies 40 each comprise two second switches 46 connected to the same output voltage supply terminal 44, these second switches 46 being denoted K11, K3>b respectively Ki>2, K32. The other second switching assembly 40 comprises two second switching branches 42, the two second switches 46 then being denoted K[ 3, K23 for one of the two second switching branches 42, and respectively K3 3, K43 for the other of the two second switching branches 42, this other second switching assembly 40 being associated with the output voltage Vout_3, of index j equal to 3.

[0113] Among the two supply terminals 44 of the output voltage Vout, one has a lower potential, noted Voutn, and the other has a higher potential, noted Voutp.

[0114] When the electrical energy converter 10 is configured to deliver several distinct output voltages Voutj, such as in the examples of FIGS. 10 and 12, it comprises, for each respective output voltage Voutj, a second respective switching assembly 40. In these examples of FIGS. 10 and 12, the lower potentials of the output voltages Vout_i, Vout_2, or even Vout 3 ([Fig. 10]), are respectively denoted Voutni, Voutn2, Voutn3, and the higher potentials of the output voltages Vout_i, Vout 2, or even Vout 3 are respectively denoted Voutpi, Voutp2, Voutp3.

[0115] According to the invention, the converter 10 further comprises an electrical transformer 80 comprising at least one primary winding 82 and at least one secondary winding 84, each primary winding 82 being connected to a first switching assembly 30, each secondary winding 84 being connected to a second switching assembly 40.

[0116] Generally, the voltage across the primary winding 82, also called the primary voltage, is denoted VI, the voltage across the secondary winding 84, also called the secondary voltage, is denoted V2, and the transformation ratio m of the electrical transformer 80 is equal to the ratio of the secondary voltage V2 divided by the primary voltage VI. In other words, the primary voltage VI is equal to m times the secondary voltage V2, according to the following equation:

[0117] [Math.l] VI - m • V2

[0118] where V2 represents the voltage across the terminals of the secondary winding 84,

[0119] V1 represents the voltage across the terminals of the primary winding 82, and

[0120] m represents the transformation ratio of the electrical transformer 80.

[0121] In the example of [Fig. 11], the electrical transformer 80 comprises two primary windings 82, the voltage across one primary winding 82 then being denoted V 1,1, and that across the terminals of the other primary winding 82 being denoted VI,2.

[0122] In the example of [Fig. 12], the electrical transformer 80 comprises two secondary windings 84, the voltage across one secondary winding 84 then being denoted V2,1, and that across the other secondary winding 84 being denoted V2,2.

[0123] The electrical transformer 80 is for example a magnetic transformer, and then further comprises a magnetic core 86, each winding 82, 84 then being arranged around the magnetic core 86.

[0124] Alternatively, the electrical transformer 80 is an air transformer, and then does not have a magnetic core. This variant is particularly suitable when the electrical energy converter 10 operates at high frequency, such as a frequency greater than 10 MHz.

[0125] The electrical transformer 80 is for example still an autotransformer, for which a part of the turns is shared between two windings, for example shared between the primary winding 82 and the secondary winding 84, or shared between two primary windings 82, or even shared between two secondary windings 84.

[0126] According to the invention, each piezoelectric assembly 12 is connected between a switch 36, 46 and a respective winding 82, 84. In other words, each piezoelectric assembly 12 is connected between a switching assembly 30, 40 and a respective winding 82, 84. By convention, each piezoelectric assembly 12 is connected by its first end 16 to a respective switching assembly 30, 40, and by its second end 18 to a respective winding 82, 84.

[0127] Each piezoelectric assembly 12 is connected between a first switch 36 and a primary winding 82, or is connected between a second switch 46 and a secondary winding 84.

[0128] As an optional addition, the converter 10 comprises at least one pair of piezoelectric assemblies 12 connected to the same respective winding 82, 84, as shown in the examples of FIGS. 1, 2, 4, 13 and 15.

[0129] In the examples of figures 1 and 4, the converter 10 comprises two pairs of piezoelectric assemblies 12, a first pair of piezoelectric assemblies 12 being connected to the primary winding 82 and a second pair of piezoelectric assemblies 12 being connected to the secondary winding 84.

[0130] In the examples of Figures 2, 13 and 15, the converter 10 comprises a single pair of piezoelectric assemblies 12. In these examples, the pair of piezoelectric assemblies 12 is connected to the primary winding 82.

[0131] In the other examples of Figures 3 and 5 to 12, the converter 10 comprises at most one piezoelectric assembly 12 connected to each respective winding 82, 84. In the examples of Figures 3, 6, 9 and 10, the converter 10 comprises a single piezoelectric assembly 12, connected to the primary winding 82. In the examples of Figures 5, 7 and 8, the converter 10 comprises two piezoelectric assemblies 12, one being connected to the primary winding 82 and the other being connected to the secondary winding 84. In the example of [Fig. 11], the converter 10 comprises two piezoelectric assemblies 12, one being connected to one of the two primary windings 82 and the other being connected to the secondary winding 84. In the example of [Fig. 12], the converter 10 comprises two piezoelectric assemblies 12, each being connected to a respective secondary winding 84.

[0132] In the examples of Figures 1 to 3, 5, 6, 8, 11 to 13 and 15, each piezo assembly 12 is connected between, on the one hand, a respective midpoint 38, 48, and on the other hand, a respective winding 82, 84. In particular, in the examples of Figures 1, 2, 13 and 15, the piezoelectric assemblies 12 of each pair connected to the primary winding 82 are each connected between a respective first midpoint 38 and the primary winding 82. Furthermore, in the example of [Fig.l], the piezoelectric assemblies 12 of the pair connected to the secondary winding 84 are each connected between a respective second midpoint 48 and the secondary winding 84. In the examples of Figures 3 and 6, the single piezoelectric assembly 12 is connected between a respective first midpoint 38 and the primary winding 82.In the examples of Figures 5, 8 and 11, one piezoelectric assembly 12 is connected between a respective first midpoint 38 and the primary winding 82, and the other piezoelectric assembly 12 is connected between a respective second midpoint 48 and the secondary winding 84. In the example of [Fig. 12], each piezoelectric assembly 12 is connected between a respective second midpoint 48 and a respective secondary winding 84.

[0133] In the example of [Fig.4], for the pair of piezoelectric assemblies 12 connected to the primary winding 82, one piezoelectric assembly 12 is connected between a respective midpoint 38 and the primary winding 82, and the other piezoelectric assembly 12 is connected between an input voltage application terminal 34 and the primary winding 82; and for the pair of piezoelectric assemblies 12 connected to the secondary winding 84, each piezoelectric assembly 12 is connected between a respective second midpoint 48 and the secondary winding 84.

[0134] In the example of [Fig.7], one piezoelectric assembly 12 is connected between a respective midpoint 38 and the primary winding 82, and the other piezoelectric assembly 12 is connected between an output voltage supply terminal 44 and the secondary winding 84.

[0135] In the examples of Figures 9 and 10, the single piezoelectric assembly 12 is connected between an input voltage application terminal 34 and the primary winding 82.

[0136] In addition, each winding 82, 84 is preferably connected to at least one piezoelectric assembly 12 or else has between its ends 88 (referenced in FIGS. 9 and 10) a voltage of substantially zero average value over a respective resonance cycle, the control device 20 then being configured to control the switches 36 or 46 of the switching assembly 30 or 40 connected to said winding 82, 84 so as to obtain said voltage of substantially zero average value.

[0137] According to this addition, when the converter 10 comprises several piezoelectric assemblies 12, each winding 82, 84 is preferably connected to at least one piezoelectric assembly 12. In other words, according to this addition and when the converter 10 comprises several piezoelectric assemblies 12, at least one piezoelectric assembly 12 is connected to the primary winding 82, and at least one other piezoelectric assembly 12 is connected to the secondary winding 84.

[0138] According to this addition, when the converter 10 comprises a single piezoelectric assembly 12 connected to a respective winding 82; 84, and the or each other winding 84; 82 has between its ends 88 a voltage of substantially zero average value over a respective resonance cycle.

[0139] Each piezoelectric assembly 12 comprises at least one piezoelectric element 15.

[0140] Preferably, each piezoelectric assembly 12 is constituted according to one of the constitutions among the group consisting of: a single piezoelectric element 15; several piezoelectric elements 15 connected in series; several piezoelectric elements 15 connected in parallel; a piezoelectric element 15 and an auxiliary capacitor, not shown, connected in series; a piezoelectric element 15 and an auxiliary capacitor connected in parallel; and an arrangement of several parallel branches, each branch comprising one or more piezoelectric elements 15 connected in series or an auxiliary capacitor.

[0141] The auxiliary capacitor is typically of greater capacity, preferably at least three times greater, than a reference capacity Co, described below, of the piezoelectric element(s) 15.

[0142] As an optional addition, the or each pair of piezoelectric assemblies 12 share the same piezoelectric material, while having the electrodes of a respective piezoelectric assembly 12 distinct from those of the other piezoelectric assembly 12 of said pair. According to this optional addition, the pairs of electrodes of a respective piezoelectric assembly 12, and respectively those of the other piezoelectric assembly 12 of said pair, cover distinct material surfaces. Furthermore, the electrodes of a respective piezoelectric assembly 12 cannot in this case directly induce a significant electric field in the part of the piezoelectric material belonging to the other piezoelectric assembly 12 of said pair.According to this optional addition, the capacitance between any one of the electrodes of a respective piezoelectric assembly 12 and any one of the electrodes of the other piezoelectric assembly 12 of said pair is negligible (at least 10 times lower) compared to a reference capacitance Co, described below, of each of the assemblies 12, for example by not being directly opposite each other on either side of the material. This pooling of the same material makes it possible, for example, to facilitate the implementation of the pair of piezoelectric assemblies 12 (limiting the number of part(s), pooling of the fixing means); and also to synchronize the vibration of the two. piezoelectric assemblies 12, without however there being a significant transfer of energy from one assembly 12 to the other ( <l / 10ème de la puissance de sortie).

[0143] The piezoelectric element 15 is known per se, and is typically modeled, close to the resonance mode used, in the form of a capacitor 52 and a resonant branch 54 connected in parallel with the capacitor 52, the capacitor 52 and the resonant branch 54 being connected between a first electrode 56 and a second electrode 58 of the piezoelectric element 15, as illustrated in the modeling of the piezoelectric element 15 represented in a bubble 60 in [Fig.l]. The resonant branch 54 is typically an RLC branch formed of a capacitor 62, a resistor 64 and an inductor 66 connected in series. The capacitance of the capacitor 52 connected in parallel with the resonant branch 54 is called parallel capacitance, or blocked capacitance, or reference capacitance, and denoted Co. The voltage across the terminals of the piezoelectric element 15 then typically corresponds to the voltage across the terminals of the capacitor 52.

[0144] In the present description, a so-called total piezoelectric voltage Vp is by convention the sum of each of the voltages at the terminals of the piezoelectric assemblies 12 brought back to the primary of the electrical transformer 80.

[0145] By convention, in the present description, the total piezoelectric voltage Vp represents the total voltage, seen from the primary side of the electrical transformer 80, of the piezoelectric assemblies 12 which act in series. Thus, the voltages at the terminals of the piezoelectric assemblies 12 which are connected to the secondary winding 84 are multiplied by the transformation ratio m of the electrical transformer 80, when brought back to the primary.

[0146] In the examples of Figures 1 and 4, the total piezoelectric voltage Vp then verifies the following equation:

[0147] [Math.2] V ^V.+ V. + mV^+mV, P p^ p3 p2 p4

[0148] where Vpi, Vp3 represent the respective voltages at the terminals of each of the piezoelectric assemblies 12 connected to the primary winding 82, and

[0149] Vp2, Vp4 represent the respective voltages at the terminals of each of the piezoelectric assemblies 12 connected to the secondary winding 84.

[0150] Similarly, in the examples of Figures 2, 13 and 15, the total piezoelectric voltage Vp then verifies the following equation:

[0151] [Math.3]

[0152] where Vpi, Vp3 represent the respective voltages at the terminals of each of the piezoelectric assemblies 12 connected to the primary winding 82.

[0153] In the examples of figures 3, 6, 9 and 10, the total piezoelectric voltage Vp is equal to the voltage across the terminals of the single piezoelectric assembly 12.

[0154] In the examples of Figures 5, 7 and 8, the total piezoelectric voltage Vp then verifies the following equation:

[0155] [Math.4] V = V , + m ■ V pp} p2

[0156] where Vpi represents the voltage across the piezoelectric assembly 12 connected to the primary winding 82, and

[0157] Vp2 represents the voltage across the piezoelectric assembly 12 connected to the secondary winding 84.

[0158] In the example of [Fig. 12], with two distinct output voltages Vout_i, Vout 2, each associated with a respective secondary winding 84, and a piezoelectric assembly 12 connected to each secondary winding 84, there are two distinct piezoelectric voltages, controlled independently of each other by the electronic control device 20, namely a first piezoelectric voltage Vpouti and a second piezoelectric voltage Vp_out2.

[0159] In this example of [Fig.12], the first piezoelectric voltage Vp outi verifies the following equation:

[0160] [Math.5] V . = ml ■ V . . p_outl p2,l

[0161] where Vp outi represents the first piezoelectric voltage, i.e. the piezoelectric voltage brought back to the primary for the piezoelectric assembly 12 connected to the secondary winding 84 associated with the first output voltage Vout_i,

[0162] Vp2>i represents the voltage across said piezoelectric assembly 12 connected to the secondary winding 84 associated with the first output voltage Vout_i, and

[0163] ml is the transformation ratio between the primary winding 82 and the secondary winding 84 associated with the first output voltage Vout_i, verifying the equation:

[0164] [Math.6] VI = ml ■ V2,l

[0165] where V2,l represents the voltage across said secondary winding 84 associated with the first output voltage Vout_i,

[0166] V1 represents the voltage across the primary winding 82, and

[0167] ml represents said transformation ratio.

[0168] In this example of [Fig.12], the second piezoelectric voltage Vp_out2 verifies the following equation:

[0169] [Math.7] V = m2 • V ,, p_oia2 p 2,2

[0170] where Vp out2 represents the second piezoelectric voltage, i.e. the piezoelectric voltage brought back to the primary for the piezoelectric assembly 12 connected to the secondary winding 84 associated with the second output voltage Vout 2,

[0171] Vp2>2 represents the voltage across said piezoelectric assembly 12 connected to the secondary winding 84 associated with the second output voltage Vout 2, and

[0172] m2 is the transformation ratio between the primary winding 82 and the secondary winding 84 associated with the second output voltage Vout 2, verifying the equation:

[0173] [Math.8] VI = m2 • V2.2

[0174] where V2,2 represents the voltage across said secondary winding 84 associated with the second output voltage Vout 2,

[0175] V1 represents the voltage across the primary winding 82, and

[0176] m2 represents said transformation ratio.

[0177] The first piezoelectric voltage Vp outi thus makes it possible to manage the current exchanged with the first output voltage Vout_i, and the second piezoelectric voltage Vp out2 makes it possible to manage the current exchanged with the second output voltage Vout 2, and this independently between the first output voltage Vout_i and the second output voltage Vout 2, as well as between the respective currents associated with these distinct output voltages Vout_i, Vout 2.

[0178] Similarly, in the example of [Fig. 11], with two distinct input voltages Vin_i, Vin 2, each associated with a respective primary winding 82, there are also two distinct piezoelectric voltages, controlled independently of each other by the electronic control device 20, namely a first piezoelectric voltage V p outi and a second piezoelectric voltage Vp in2.

[0179] In this example of [Fig.l 1], the first piezoelectric voltage Vpouti verifies the following equation:

[0180] [Math.9] V , = ml' -V , p_outl p 2

[0181] where Vp outi represents the first piezoelectric voltage in this example, that is to say the piezoelectric voltage brought back to the primary of the first input voltage Vin_i, for the piezoelectric assembly 12 connected to the secondary winding 84,

[0182] Vp2 represents the voltage across said piezoelectric assembly 12 connected to the secondary winding 84, and

[0183] ml' is the transformation ratio between the primary winding 82 associated with the first input voltage Vin_i and the secondary winding 84, verifying the following equation:

[0184] [Math. 10] VI,1 = ml' • V2

[0185] where V2 represents the voltage across the secondary winding 84,

[0186] VI,1 represents the voltage across said primary winding 82 associated with the first input voltage Vin_i, and

[0187] ml' represents said transformation ratio.

[0188] In this example of [Fig.l 1], the transformation ratio between the primary winding 82 associated with the second input voltage Vin 2 and the secondary winding 84 is noted m2' and verifies the equation:

[0189] [Math. 11] VI,2 = m2' • V2

[0190] where V2 represents the voltage across the secondary winding 84,

[0191] VI,2 represents the voltage across said primary winding 82 associated with the second input voltage Vin_2, and

[0192] m2' represents said transformation ratio.

[0193] In this example of [Fig.l 1], the second piezoelectric voltage Vp_in2 verifies the following equation:

[0194] [Math. 12] V • .= V , p_ni2 p\

[0195] where Vp_in2 represents the second piezoelectric voltage in this example of [Fig.l 1], i.e. the piezoelectric voltage at the primary for the piezoelectric assembly 12 connected to the primary winding 82 associated with the second input voltage Vin 2, and

[0196] Vpi represents the voltage across said piezoelectric assembly 12 connected to the primary winding 82 associated with the second input voltage Vin 2.

[0197] Those skilled in the art will then understand that in the example of [Fig. 11], the control principle is the same as in the example of [Fig. 12], except that instead of controlling the second output to provide a second output voltage Vout 2, the control is modified so that the current reverses and the second output becomes an input. This input is controlled relative to the first input. It is then as if the second input voltage Vin 2 supplied power to the first input voltage Vin_i which itself sends power to the output voltage Vout. This then allows independent control of the output voltage Vout on the one hand, and of the current drawn on the second input voltage Vin 2 on the other hand.

[0198] As a variant of the example of [Fig. 11], instead of connecting a piezoelectric assembly 12 to the secondary winding 84, a piezoelectric assembly 12 is connected to the primary winding 82 associated with the first input voltage Vin_i. According to this variant, the two input voltages Vin_i, Vin 2 are then controlled with respect to of the output voltage Vout.

[0199] Those skilled in the art will understand that in practice, on a winding 82, 84 where there is no piezoelectric assembly 12 connected, no control can be carried out to differentiate a current which would go to one output rather than another. It is therefore on the windings 82, 84 to which a respective piezoelectric assembly 12 is connected that it is possible to control the exchanged current; and the or each winding 82, 84 without piezoelectric assembly 12 undergoes the control, and compensates for the total balance of the exchanged powers, the sum of the output powers being equal to the sum of the input powers apart from losses.

[0200] Furthermore, in the present description and as shown in Figures 1 to 9, 13 and 15, the voltage between the first midpoints 38 is denoted Vpa, and is equal to the potential difference (Vpal - Vpa2), where Vpai is the potential of one of the two first midpoints 38, and Vpa2 is the potential of the other first midpoint 38. By convention, when the first switching assembly 30 comprises a single first switching branch 32, the potential among Vpai, Vpa2 which is not associated with the first midpoint 38 of this first switching branch 32 then corresponds to the potential Vinn, Vinp of one of the two input voltage application terminals 34 or to that of a respective end 88 of the primary winding 82. In the examples of Figures 4 to 10, the potential Vpa2 is equal to the lower potential Vinn of the input voltage.

[0201] When the electrical energy converter 10 is configured to receive several distinct input voltages Vin k, such as in the example of [Fig. 11], the voltage between the first midpoints 38 is denoted Vpa k for each first switching assembly 30 associated with the respective input voltage Vink, and is equal to the potential difference (Vpaijk - Vpa2jk), where Vpaijk is the potential of one of the two first midpoints 38, and Vpa2jk is the potential of the other first midpoint 38 of said first switching assembly 30, with the aforementioned convention remaining applicable.

[0202] The voltage between the second midpoints 48 is denoted Vpb, and is equal to the potential difference (Vpb2 - Vpbi), where Vpbi is the potential of one of the two second midpoints 48, and Vpb2 is the potential of the other second midpoint 48. Also by convention, when the second switching assembly 40 comprises a single second switching branch 42, the potential among Vpbl, Vpb2 which is not associated with the second midpoint 48 of this second switching branch 42 then corresponds to the potential Voutn, Voutp of one of the two output voltage supply terminals 44 or to that of a respective end 88 of the secondary winding 84. In the example of [Fig.7], the potential Vpbi is equal to the lower potential Voutn of the output voltage; and in that of [Fig.8], the potential Vpb2 is equal to said lower potential Voutn of the output voltage. In the example of the [Fig.9], each potential Vpbl, Vpb2 is equal to the potential of a respective end 88 of the secondary winding 84.

[0203] When the electrical energy converter 10 is configured to deliver several distinct output voltages Voutj, such as in the examples of FIGS. 10 and 12, the voltage between the second midpoints 48 is denoted Vpbj for each second switching assembly 40 associated with the respective output voltage Voutj, and is equal to the potential difference (Vpb2j - Vpbij), where Vpbij is the potential of one of the two second midpoints 48, and Vpb2j is the potential of the other second midpoint 48 of said second switching assembly 40, with the aforementioned convention remaining applicable.

[0204] The resonance frequency is the frequency at which the piezoelectric element 15 oscillates and consequently its current IL, shown in [Fig.l]. The conversion cycle is synchronized with a mechanical movement of the piezoelectric element 15, and the control frequency is then set to the mechanical oscillation frequency. In practice, this oscillation frequency depends on the operating point of the converter 10: values ​​of the three voltage levels and the output current. Depending on the operating point, this oscillation frequency typically varies between the so-called series resonance frequency of the piezoelectric element 15 (cos=l / '> / (Lr.Cr ) where Lr and Cr correspond to the inductance and capacitance of the resonant branch 54) and the so-called parallel resonance frequency of the piezoelectric element 15 (cop=l / '' / (Lr.Cr.Co / (Cr+C0))), also respectively called the resonance frequency and antiresonance frequency of the piezoelectric element 15.The operating frequency of the converter 10 is then between these two resonance and antiresonance frequencies of the piezoelectric element 15. The operating point varies slowly with respect to the oscillation frequency of the piezoelectric element 15. The operating point typically varies at less than 10kHz, while the oscillation frequency of the piezoelectric element 15 is typically greater than or equal to 100kHz. As a result, the operating frequency of the converter 10 varies little from one period to the next.

[0205] As an optional addition, when the converter 10 comprises several piezoelectric assemblies 12 connected to the primary winding 82, said piezoelectric assemblies 12 at the primary, and the piezoelectric elements 15 constituting them, are preferably substantially identical to each other.

[0206] As an optional addition and in a similar manner, when the converter 10 comprises several piezoelectric assemblies 12 connected to the secondary winding 84, said piezoelectric assemblies 12 to the secondary, and the piezoelectric elements 15 constituting them, are preferably substantially identical to each other.

[0207] By piezoelectric assemblies 12 substantially identical to each other, we mean that they have the same reference capacity Co to within 10% and the same resonance frequency to within 10%.

[0208] As an optional addition, the piezoelectric assembly(s) 12 connected to the secondary winding 84 have a reference capacitance Co substantially equal to m times the reference capacitance Co of the piezoelectric assembly(s) 12 connected to the primary winding 82, to within 50%.

[0209] Generally speaking, for the electrical energy converter 10 with the piezoelectric assemblies 12 and controlled by the electronic control device 20, the number of phases at substantially constant voltage is typically at least 2, preferably equal to 3, while being able to be greater than or equal to 4 with the implementation of the control described in application FR 21 07345 filed on July 7, 2021.

[0210] Each phase at substantially constant voltage is capable of being obtained from a combination of the input and output voltages, in positive or negative value, while taking into account the transformation ratio m of the electrical transformer 80, as explained below, in particular with regard to table 1. The energy converter 10 then makes it possible to exchange energy during the phases at substantially constant voltage, and consequently, with the voltage combinations used to obtain these phases at substantially constant voltage. It is in particular possible to transfer energy from a phase at substantially constant voltage of low voltage to a phase at substantially constant voltage of higher voltage, and by the play of the aforementioned combinations ultimately obtain a voltage step-down converter, which may seem counter-intuitive.Conversely, it is also possible to transfer energy from a phase with a substantially constant voltage of high voltage to a phase with a substantially constant voltage of lower voltage, and by the play of the aforementioned combinations ultimately obtain a voltage boost converter. Those skilled in the art will then understand that it is possible to have a boost cycle seen by the piezoelectric assemblies 12 while the electrical energy converter 10 is a step-down converter, and conversely to have a step-down cycle seen by the piezoelectric assemblies 12 while the electrical energy converter 10 is a step-up converter.

[0211] By convention, if a current is supplied to the piezoelectric assemblies 12 during the substantially constant voltage phase corresponding to the highest voltage during a resonance cycle, then the cycle is considered a step-down cycle for the piezoelectric assemblies 12. Conversely, if a current is supplied, or drawn, from the piezoelectric assemblies 12 during said substantially constant voltage phase for which the voltage is the highest during the resonance cycle, then the cycle is considered a step-up cycle for the piezoelectric assemblies 12. As indicated previously, the conversion cycle seen by the piezoelectric assemblies 12 is likely to be a step-up cycle while the electrical energy converter 10 operates as a step-down converter, and conversely the conversion cycle seen by the piezoelectric assemblies 12 is likely to be a step-down cycle while the electrical energy converter 10 operates as a step-up converter.

[0212] The electronic control device 20 is configured to control the electrical energy converter 10, in particular to control the control of the switches 36, 46 of the converter, in order to alternate, during a respective resonance cycle of the piezoelectric assemblies 12, phases at substantially constant voltage at the terminals of the piezoelectric assemblies 12 and phases at substantially constant charge, that is to say in substantially open circuit, at the terminals of said piezoelectric assemblies 12.

[0213] The electronic control device 20 is for example produced in the form of an electronic circuit comprising one or more electronic components.

[0214] Alternatively, the electronic control device 20 is produced in the form of a programmable logic component, such as an FPGA (Field Programmable Gate Array), or in the form of an integrated circuit, such as an ASIC (Application Specific Integrated Circuit) or even in the form of a computer, such as a microcontroller, a processor.

[0215] As an optional addition, when the converter 10 comprises several piezoelectric assemblies 12, the electronic control device 20 is further configured to control the switches 36, 46 of the converter, in order to operate all the piezoelectric assemblies 12 substantially at the same resonant frequency, such as at the same resonant frequency to within 10%.

[0216] Each of the first 36 and second 46 switches is preferably a unidirectional current and unidirectional voltage switch. The switch 36, 46 comprises, for example, a transistor, or a diode, or a transistor and a diode in antiparallel, not shown. The switch 36, 46 is preferably made up of the transistor, or the diode, or the transistor and the diode in antiparallel. Alternatively, the switch 36, 46 comprises a combination of several transistors, and is preferably made up of such a combination of several transistors. As a further variant, the switch 36, 46 comprises a mechanical switch, such as a MEMS (MicroElectroMechanical System) microswitch.

[0217] The transistor is, for example, an insulated gate field effect transistor, also called a MOSFET (from the English Metal Oxide Semiconductor Field Effect Transistor). Alternatively, the transistor is a bipolar transistor; an insulated gate bipolar transistor, also called an IGBT (from the English Insulated Gate Bipolar Transistor); a silicon (Si) based transistor, a GaN (from Gallium Nitride); a silicon carbide (SiC) based transistor, or a diamond based transistor, or a thyristor.

[0218] As an optional addition, a winding 82, 84 comprises, between its ends 88, at least one intermediate point 90 connected to a respective switching assembly 30, 40 or to a respective input voltage application terminal 34 or output voltage supply terminal 44.

[0219] According to this optional addition, in the example of [Fig.9], the secondary winding 84 comprises, between its ends 88, an intermediate point 90 connected to a respective output voltage supply terminal 44, namely the one having the higher output voltage potential Voutp. In the example of [Fig.10], the secondary winding 84 comprises, between its ends 88, several intermediate points 90. Some intermediate points 90 are connected to a respective second switching assembly 40, namely the one associated with the output voltage Vout_2- Another intermediate point 90 is connected to several respective output voltage supply terminals 44, namely those with higher output voltage potentials Voutpi, V outp2.

[0220] According to this optional addition, in a variant not shown, the primary winding 82 comprises, between its ends 88, an intermediate point 90 connected to a respective first switching assembly 30, or to a respective input voltage application terminal 34.

[0221] With the converter 10 according to the invention, those skilled in the art will observe that due to the presence of at least one piezoelectric assembly 12, connected to the primary winding 82, or respectively to the secondary winding 84, the or each piezoelectric assembly 12 also makes it possible to reduce, or even eliminate, a DC component via its capacitive behavior at low frequency, i.e. for a frequency lower than one tenth of that of a first resonance mode. Thus, if the voltage Vpa and / or the voltage Vpb have a DC component, it will be reduced, or even eliminated, by the piezoelectric assembly 12, connected to the primary winding 82, or respectively to the secondary winding 84. The voltages at the primary V1 and at the secondary V2 then have a substantially zero DC component, which allows better operation of the electrical transformer 80 without risk of current drift.

[0222] Furthermore, even if the electrical transformer 80 offers a first level of insulation, the piezoelectric assembly(s) 12 add a complementary level of insulation, for example to achieve a reinforced level of insulation which guarantees, for example, insulation even in the event of the appearance of a first fault.

[0223] The operation of the converter 10 according to the invention is then analogous to that of each of the electrical energy converters described in applications FR 21 12925, FR 21 12926 and FR 21 12933 filed on December 3, 2021, with the difference in the values voltage during phases with substantially constant voltage at the terminals of the piezoelectric assemblies 12, also called voltage step values, these voltage step values ​​being, due to the transformation ratio m of the electrical transformer 80, likely to differ from those described in the aforementioned applications.

[0224] In the example of figures 1 to 9, 13 and 15, apart from the DC component and due to the topology of the converter 10, the electronic control device 20 is then configured to, during the phases at substantially constant voltage across the terminals of the piezoelectric assemblies 12, control the control of the switches 36, 46 of the converter 10, in order to have the value of the voltage of each of the phases at substantially constant voltage, chosen from the group of values ​​defined in table 1 below for each of the figures:

[0225] [Tables 1] Figure Possible values ​​for each voltage step, with the converter of the respective figure Figure 1 0 , “Vin ? +Vin , _mVOut , +mVOut , -Vin-mVout , ”Vin“l“mVout , Vin-mVout , Vin +mVout Figure 2 0 ; -Vin ; +vin ; -mVout ; +mVout ; -Vin-mVout ; -Vin+mVout ; Vin-mVout ; Vin +mVout Figure 3 0, “Vin, +Vin, _mVOut, “HHVont, -Vin-mVout, ”Vin“l“mVout, Vin-mVout, Vin +mVout Figure 4 0; +Vin; -mVout; +mVout; Vin-mVout; Vin+mVout Figure 5 0; +Vin; -mVout; +mVout ; Vin-mVout Figure 6 0 , +Vin, -mVout ? Vin-i-mVout Figure 7 0 ; +Vin ; -mVout ? Vin-i-mVout Figure 13 0 ; -Wine ; +Wine; -mVout; +mVout ; -Vin-mVout; -Vin+mVout; Vin-mVout ; Vin +mVout Figure 15 0 ; -Wine ; +Wine; -mVout; +mVout ; -Vin-mVout; -Vin+mVout; Vin-mVout ; Vin +mVout

[0226] where Vin represents the input voltage, Vout represents the output voltage and m represents the transformation ratio of the electrical transformer 80, and taking into account the previous equations (2) to (4).

[0227] In the examples of Figures 7 and 8, those skilled in the art will observe that, by the topology of the converter 10, the voltage Vpa cannot be negative and therefore necessarily includes a DC component, and the same goes for the voltage Vpb. As the voltages at the primary VI and at the secondary V2 are in principle without a DC component, the DC component of the voltage Vpa is then eliminated by the piezoelectric assembly 12 arranged between this voltage Vpa and the primary winding 82, to form the voltage at the primary VI. A DC component is then reintroduced into the voltage Vpb relative to the voltage at the secondary V2, via the piezoelectric assembly 12 arranged between the primary winding 84 and this voltage Vpb. Compared to a cycle of a converter of the state of the art without an electrical transformer, it is then possible to have a modification of the DC component of the total piezoelectric voltage Vp.However, in steady state, there is a balance of charges exchanged on each of the piezoelectric assemblies 12 over a period of mechanical oscillation, and the possible presence of a direct voltage component on the piezoelectric assemblies 12 therefore does not modify the balance of energy exchanged over a period of mechanical oscillation (❖iL.Vpbmoydt=0). The person skilled in the art will then understand the precision “to the nearest DC component” indicated above, for the presentation of the possible values ​​of the voltage levels. Indeed, it is possible for a DC component to be added during the phases at substantially constant voltage and on each of the piezoelectric assemblies 12, without this modifying the behavior of the converter 10 according to the invention, in terms of output power, amplitude of the current IL flowing in the piezoelectric elements 15, or even regulation.

[0228] In the example of [Fig.9], the switches K7 and K8 have been removed at the primary with respect to a topology with two first switching branches 32, and those skilled in the art will observe that as a variant, the switches K5 and K6 could have been removed, by then connecting an intermediate point 90 of the primary winding 82 to the lower potential Vinn or higher Vinp of the input voltage.

[0229] Similarly, switches K2 and K4 have been removed from the secondary with respect to a topology with two second switching branches 42, while connecting the intermediate point 90 of the secondary winding 84 to the higher output voltage potential Voutp, and those skilled in the art will observe that alternatively, switches Ki and K3 could have been removed, then connecting the intermediate point 90 of the secondary winding 84 to the lower output voltage potential Voutn.

[0230] Those skilled in the art will note that in the example of [Fig.9], the piezoelectric assembly 12 cannot be placed on the side of the winding 82, 84 with the intermediate point 90, because if it is in series with a switch, it will be disconnected over at least half a period and it will then not be possible to apply a voltage step over this half period. And if the piezoelectric assembly 12 is connected in series with the intermediate point 90, as the latter must exchange a substantially zero average quantity of charges over a period (charge balance), then there cannot be any power exchanged with the output voltage being substantially constant over a resonance period. On the other hand, it is possible to completely reverse the input and output to find an intermediate point 90 at the primary and the piezoelectric assembly(s) 12 at the secondary.

[0231] In the example of [Fig.10], the secondary voltages V2,l, V2,2 and V2,3 are proportional to each other according to the ratios ml”= Vl / V2,l; m2”=Vl / V2,2 and m3”= Vl / V2,3 relative to each of the outputs of the electrical transformer 80.

[0232] In the example of [Fig. 10], the electrical transformer 80 has been shown with a single secondary winding 84 and outputs which exploit more or fewer turns of this same secondary winding 84.

[0233] As a variant, the electrical transformer 80 comprises several secondary windings 84 completely independent of each other, for example in order to obtain secondary voltages V2,1, V2,2 isolated from each other, as in the example above [Fig. 12],

[0234] Those skilled in the art will further observe that it is possible, in the manner of figures 17 and 18 of patent FR 3 086 472, to regulate each of the outputs separately by successively connecting each of them. Typically by cutting the voltage levels in which the output voltage appears into voltage sub-levels with the different output voltages. In this case, certain switches Ki i, K24, K3>i, K41, Ki>2, K2>2, K3>2, K4 2 of the converter 10 of [Fig. 10] must be bidirectional in voltage, to be able to isolate an output while a current is supplied to another output requiring a higher voltage at the primary V1.

[0235] In the example of [Fig. 10], the piezoelectric assembly 12 is arranged at the primary, and it is shared for the operation of all the outputs, and the current of the piezoelectric assembly 12 is then divided into several output currents.

[0236] Alternatively, it is possible to connect a piezoelectric assembly 12 to each of the outputs, as in the example of [Fig.12]. In this case, it is not essential to use bidirectional voltage transistors to individually control each output. Indeed, each of the output voltages can be controlled independently without going through sub-steps from the moment when the cycles for the output voltages Vout_i and Vout 2 are compatible to have in common the same evolution of the voltage Vpa. By a differentiated control of the voltages Vpb_i and Vpb 2, it is possible to obtain differentiated cycles for the first and second piezoelectric voltages Vp outi and Vp_out2, and thus to control in a differentiated manner the output voltages Vout_i and Vout_2.

[0237] In Figures 13 and 14, according to a complementary aspect of the invention and when the converter 10 comprises at least one pair of piezoelectric assemblies 12 connected to the same respective winding 82, 84, the converter 10 further comprises at least one switching assistance circuit 50, each switching assistance circuit 50 being connected between the first ends 16 of a respective pair of piezoelectric assemblies 12, corresponding to the first midpoints 38 of the first switching assembly 30 when said pair of piezoelectric assemblies 12 is connected to the first switching assembly 30, and corresponding respectively to the second midpoints 48 of the second switching assembly 40 when said pair of piezoelectric assemblies 12 is connected to the second switching assembly 40.Each switching assistance circuit 50 being configured to, via the circulation of a previously received current, discharge a parasitic capacitance of at least one switch 36, 46 of the respective switching assembly 30, 40 to which it is connected, and respectively charge at least one parasitic capacitance of another switch 36, 46 of said switching assembly 30, 40.

[0238] In the example of [Fig. 13], the converter 10 comprises a single switching aid circuit 50 connected to the first switching assembly 30.

[0239] As a variant, not shown, the converter 10 comprises a single switching assistance circuit 50 connected to the second switching assembly 40.

[0240] As a variant, not shown, the converter 10 comprises two switching assistance circuits 50, a first switching assistance circuit being connected to the first switching assembly 30 and a second switching assistance circuit being connected to the second switching assembly 40.

[0241] Each switching assistance circuit 50 is configured, via the circulation of a previously received current ICalc, to discharge at least one parasitic capacitance of a switch 36, 46, preferably a switch to be closed, of the respective switching assembly 30, 40 to which it is connected; respectively to charge at least one parasitic capacitance of another switch 36, 46, preferably a switch to be opened or kept open, of said switching assembly 30, 40.

[0242] Each of the switches of said switching assembly 30 is open during the circulation, by the switching assistance circuit 50, of the previously received current.

[0243] Following this current flow, the switch(es) 36, 46 whose parasitic capacitance has been discharged by the switching aid circuit 50 is / are closed. The other switch(es) 36, 46 whose parasitic capacitance has been charged by the switching aid circuit 50 remains open. A residual current from the switching aid circuit 50 can continue to flow.

[0244] Each switching assistance circuit 50 comprises for example an inductor 70; or a first assembly formed of the inductor 70 and a diode 72 connected in series; or a second assembly formed of the inductor 70 and a capacitor 74 connected in series; or an additional piezoelectric element 76, as shown in [Fig. 14].

[0245] Each switching assistance circuit 50 is for example an inductor 70, the inductor 70 preferably consisting of a coil and a magnetic circuit. Alternatively, each switching assistance circuit 50 is in the form of the first set of the inductor 70 and the diode 72 connected in series, and preferably consisting of said first set of the inductor 70 and the diode 72. As a further alternative, each switching assistance circuit 50 is in the form of the second set of the inductor 70 and the capacitor 74 connected in series, and preferably consisting of said second set of the inductor 70 and the capacitor 74. As a further alternative, each switching assistance circuit 50 is in the form of the additional piezoelectric element 76, and preferably consisting of the additional piezoelectric element 76.

[0246] As a further variant, the electrical transformer 80 is dimensioned so as to exhibit inductive behavior in the form of an equivalent parasitic inductance placed between the terminals of the primary winding 82 and / or between those of the secondary winding 84 of the transformer. This parasitic inductance, generally called magnetizing inductance, then makes it possible to ensure this switching assistance circuit function 50. Such a magnetizing inductance is illustrated in plate 15 of the presentation entitled “Single-phase transformer” by Abdallah Darkawi of February 19, 2019.

[0247] In the exemplary embodiment where the switching assistance circuit 50 is in the form of the inductor 70 alone, the inductor 70 sees its current increase over a half-period, i.e. when the voltage across its terminals is positive; then its current decreases over the other half-period, i.e. when the voltage across its terminals is negative. This exemplary embodiment of the switching assistance circuit 50 preferably requires that the voltage across the inductor 70 be substantially zero on average, otherwise there is a risk of having a current drift. If the switching assistance circuit 50 is connected to the second assembly 40, in particular between the second midpoints 48, the voltage across the inductor 70 is the voltage Vpb. Correspondingly, if the switching assistance circuit 50 is connected to the first assembly 30, in particular between the first midpoints 38, the voltage across the inductance 70 is the voltage Vpa.

[0248] The variant where the switching aid circuit 50 is in the form of the inductor 70 and the diode 72 connected in series, makes it possible to charge the inductor 70 only over a half-period with the correct polarity, in particular for cycles where the current ICalc is received during a time period with a single polarity. In particular, the diode 72 then makes it possible to avoid charging the inductor 70 with a reverse current. This unidirectional current operation also makes it possible to reduce the effective current seen by the inductance 70 and therefore the losses. Furthermore, the switching assistance circuit 50 according to this variant is not sensitive to the presence of a DC component from the moment when the DC component is in the direction of blocking the diode 72.

[0249] The variant where the switching assistance circuit 50 is in the form of the inductor 70 and the capacitor 74 connected in series, makes it possible - compared to the example of the inductor 70 alone - to reduce, or even eliminate, a possible DC component. Nevertheless, the capacitor 74 can be quite large. Indeed, the voltage across the terminals of the capacitor 74 must change little, i.e. in a small proportion, compared to the input voltage Vin or the output voltage Vout, for example have an amplitude less than 50% of the input voltage Vin or output voltage Vout*

[0250] According to the variant where the switching assistance circuit 50 is in the form of the additional piezoelectric element 76, from the moment when the control of the converter 10 is carried out between the resonance and antiresonance frequency of the additional piezoelectric element 76, the latter begins to oscillate and to produce a current Icalc substantially in quadrature with the voltage at its terminals, such as the voltage Vpb if the additional piezoelectric element 76 is connected to the second assembly 40 between the second midpoints 48, or the voltage Vpa if the additional piezoelectric element 76 is connected to the first assembly 30 between the first midpoints 38. The current Icalc then passes through an extrema, which makes it possible to ensure the function of inverting the voltage Vpb, or respectively the voltage Vpa.

[0251] The additional piezoelectric element 76 is typically at least 3 times smaller than the piezoelectric element(s) 15 of the converter 10, the additional piezoelectric element 76 only having to charge / discharge the parasitic capacitances of the switches 36, 46. The parasitic capacitance of the switches 36, 46 is in fact considered to be at least three times lower than the reference capacitance Co of the piezoelectric element(s) 15 of the converter 10. This variant where the switching assistance circuit 50 is in the form of the additional piezoelectric element 76 is insensitive to a possible DC component (whatever its polarity), and the switching assistance circuit 50 is able to be connected both to the first assembly 30 (voltage Vpa) and to the second assembly 40 (voltage Vpb).

[0252] In other words, the reference capacitance of the additional piezoelectric element 76 is at least three times lower than the reference capacitance Co of each piezoelectric assembly 12 connected between the first 38 and second 48 respective midpoints.

[0253] In [Fig. 15], according to another complementary aspect of the invention and when the converter 10 comprises at least one pair of piezoelectric assemblies 12 connected to the same respective winding 82, 84, the converter 10 further comprises a complementary switch 28 connected directly between the first ends 16 of said pair of piezoelectric assemblies 12, said first ends 16 connected directly to each other via the complementary switch 28 being connected to the same respective switching assembly 30, 40.

[0254] In the example of [Fig. 15], the converter 10 comprises a single complementary switch 28 connected directly between the first ends 16 of the pair of piezoelectric assemblies 12 connected to the primary winding 82.

[0255] In a variant not shown, the converter 10 comprises a single complementary switch 28 connected directly between the first ends 16 of the pair of piezoelectric assemblies 12 connected to the secondary winding 84.

[0256] As a further variant, not shown, the converter 10 comprises two complementary switches 28, namely a first complementary switch 28 connected directly between the first ends 16 of the pair of piezoelectric assemblies 12 connected to the primary winding 82 and a second complementary switch 28 connected directly between the first ends 16 of the pair of piezoelectric assemblies 12 connected to the secondary winding 84.

[0257] As a further variant, not shown, and when the converter 10 comprises several pairs of piezoelectric assemblies 12, each connected to a respective winding 82, 84, the converter 10 preferably comprises a complementary switch 28 for each pair of piezoelectric assemblies 12, each complementary switch 28 then being connected between the first ends 16 of a respective pair.

[0258] In the example of [Fig. 15], the complementary switch 28 is also noted K9.

[0259] Each complementary switch 28 is preferably a bidirectional voltage switch. Each complementary switch 28 comprises, for example, two unidirectional, i.e. monodirectional, voltage switches placed head to tail in series. Each unidirectional switch comprises, for example, a transistor, or a diode, or a transistor and a diode in antiparallel, not shown. Each unidirectional switch is preferably made up of the transistor, or the diode, or the transistor and the diode in antiparallel.

[0260] Those skilled in the art will observe that each complementary switch 28 is alternatively a single-way voltage switch.

[0261] According to this complementary aspect of the invention, the electronic control device 20 is further configured to, during at least one phase at substantially constant voltage, control at least one respective complementary switch 28 in the closed position.

[0262] Those skilled in the art will then understand that when the converter 10 comprises a respective complementary switch 28 connected directly between the first ends 16 of a respective pair of piezoelectric assemblies 12 connected to the primary winding 82, the control in the closed position of said complementary switch 28 makes it possible to force the voltage Vpa between said first ends 16 to the zero value.

[0263] Similarly, when the converter 10 comprises a respective complementary switch 28 connected directly between the first ends 16 of a respective pair of piezoelectric assemblies 12 connected to the secondary winding 84, then the control in the closed position of said complementary switch 28 makes it possible to force the voltage Vpb between the first ends 16 to the zero value.

[0264] Similarly again, when the converter 10 comprises two complementary switches 28 connected to the first ends 16 of two respective pairs of piezoelectric assemblies 12 connected on the one hand to the primary winding 82 and on the other hand to the secondary winding 84, that is to say both the first complementary switch 28 connected directly between the first ends 16 of a respective pair of piezoelectric assemblies 12 connected to the primary winding 82 and a second complementary switch 28 connected directly between the first ends 16 of the other pair of piezoelectric assemblies 12 connected to the secondary winding 84, then the control in the closed position of these first and second complementary switches 28 makes it possible to force both the voltage Vpa to the zero value and the voltage Vpb to the zero value,and therefore to force the total piezoelectric voltage Vp of the two pairs of piezoelectric assemblies 12 to the zero value.,

Claims

Claims

1. Electronic electrical energy conversion system (5) capable of converting one or more input voltages (Vin;Vin k) into one or more output voltages (Vout;Vout j), the conversion system (5) comprising: - an electrical energy converter (10) configured to deliver N distinct output voltage(s) (Vout; Voutj), from E distinct input voltage(s) (Vin; Vin_k), E and N each being an integer greater than or equal to 1, the converter (10) comprising: + E first switching assembly(s) (30), each being associated with a respective input voltage (Vin;Vin k) and comprising at least two first switches (36), each first switch (36) being connected to a terminal (34) for applying the respective input voltage (Vin;Vin_k); + N second switching assembly(s) (40), each being associated with a respective output voltage (Vout; Voutj) and comprising at least two second switches (46), each second switch (46) being connected to a terminal (44) for supplying the respective output voltage (Vout; VoutJ); + at least one piezoelectric assembly (12), each being connected to a switch among the first (36) and second (46) switches, and comprising at least one piezoelectric element (15); - an electronic device (20) for controlling the electrical energy converter (10), the electronic control device (20) being configured to control, during a respective resonance cycle of the piezoelectric assembly(s) (12), a switching of each of the first (36) and second (46) switches to alternate phases at substantially constant voltage across the terminals of the piezoelectric assembly(s) (12) and phases at substantially constant charge across said piezoelectric assembly(s) (12), characterized in that the converter (10) further comprises an electrical transformer (80) comprising at least one primary winding (82) and at least one secondary winding (84), each primary winding (82) being connected to a first switching assembly (30), each secondary winding (84) being connected to a second switching assembly (40), and each piezoelectric assembly (12) is connected between a switch (36;46) and an en-; respective bearing (82; 84).

2. System (5) according to claim 1, wherein each piezoelectric assembly (12) is connected between a first switch (36) and a primary winding (82) or between a second switch (46) and a secondary winding (84).

3. System (5) according to claim 1 or 2, in which each winding (82, 84) is connected to at least one piezoelectric assembly (12) or has between its ends a voltage of substantially zero average value over a respective resonance cycle, the control device (20) then being configured to control the switches (36; 46) of the switching assembly (30; 40) connected to said winding (82; 84) so ​​as to obtain said voltage of substantially zero average value.

4. System (5) according to any one of claims 1 to 3, wherein the converter (10) comprises several piezoelectric assemblies (12), and each winding (82, 84) is connected to at least one piezoelectric assembly (12).

5. System (5) according to any one of claims 1 to 3, in which the converter (10) comprises a single piezoelectric assembly (12) connected to a respective winding (82; 84), and the or each other winding (84; 82) has between its ends (88) a voltage of substantially zero average value over a respective resonance cycle.

6. System (5) according to any one of the preceding claims, wherein at least one first switching assembly (30) is in the form of a first switching bridge comprising at least one first switching branch (32), each first switching branch (32) being connected between two terminals (34) for applying a respective input voltage (Vin; Vin k) and comprising at least two first switches (36) connected in series and connected together at a first midpoint (38); each first switching assembly (30) preferably being in the form of a respective first switching bridge.

7. System (5) according to claim 6, wherein at least one first switching assembly (30) comprises two first switching branches (32); each first switching assembly (30) preferably comprises two first switching branches (32).

8. System (5) according to claim 6 or 7, in which a pié- zoelectric (12) is connected between a first midpoint (38) and a respective primary winding (82).

9. System (5) according to any one of the preceding claims, in which at least one second switching assembly (40) is in the form of a second switching bridge comprising at least one second switching branch (42), each second switching branch (42) being connected between two terminals (44) for supplying a respective output voltage (Vout; Voutj) and comprising at least two second switches (46) connected in series and connected together at a second midpoint (48); each second switching assembly (40) preferably being in the form of a respective second switching bridge.

10. System (5) according to claim 9, wherein at least one second switching assembly (40) comprises two second switching branches (42); each second switching assembly (40) preferably comprises two second switching branches (42).

11. A system (5) according to claim 9 or 10, wherein a piezoelectric assembly (12) is connected between a second midpoint (48) and a respective secondary winding (84).

12. System (5) according to any one of the preceding claims, in which a winding (82, 84) comprises, between its ends (88), at least one intermediate point (90) connected to a respective switching assembly (30, 40) or to a respective terminal for applying input voltage (34) or for providing output voltage (44).

13. System (5) according to any one of the preceding claims, wherein the converter (10) comprises a pair of piezoelectric assemblies (12) connected to a same respective winding (82, 84), and further a complementary switch (28) connected directly between ends (16) of said pair of piezoelectric assemblies (12), said ends (16) connected directly to each other via the complementary switch (28) being connected to a same respective switching assembly (30; 40).

14. System (5) according to any one of the preceding claims, wherein the converter (10) comprises a pair of piezoelectric assemblies (12) connected to a same respective winding (82, 84), and further a switching assistance circuit (50) connected between ends (16) of said pair of piezoelectric assemblies (12), said ends (16) connected together via the switching assistance circuit (50) being connected to the same respective switching assembly (30; 40), the switching assistance circuit (50) being configured to, via the circulation of a previously received current, discharge a parasitic capacitance of at least one switch (36; 46) of the respective switching assembly (30; 40) to which it is connected, and respectively charge at least one parasitic capacitance of another switch (36; 46) of said switching assembly (30; 40).

15. System (5) according to claim 14, wherein the switching assistance circuit (50) comprises an element selected from the group consisting of: an inductor (70); a first assembly formed of an inductor (70) and a diode (72) connected in series; a second assembly formed of an inductor (70) and a capacitor (74) connected in series; and an additional piezoelectric element (76); the switching assistance circuit (50) preferably being constituted by an element selected from said group; the inductance (70) being preferably still in the form of a parasitic inductance of the respective winding (82, 84) to which the pair of piezoelectric assemblies (12) is connected.

16. System (5) according to any one of the preceding claims, wherein the electrical transformer (80) is an air transformer or a magnetic transformer, the magnetic transformer further comprising a magnetic core (86), each winding (82, 84) then being arranged around the core (86); the electrical transformer (80) being for example an autotransformer.

Images