Electrical energy converter and associated electrical energy conversion system

Abstract

Electrical energy converter and associated electrical energy conversion system The invention relates to an electrical energy converter comprising an inverter (10) for obtaining alternating electrical energy from a direct electrical energy source. The inverter comprises a switch (52) comprising first and second conduction terminals intended to receive an alternating voltage, said electrical energy converter being adapted to supply an output electrical energy to a load (8). This converter comprises a capacitive circuit (14) of variable and controllable capacity, connected between the inverter (10) and the load (8), the control of a modification of said capacity making it possible to obtain a modification of an electrical output parameter of the converter.The associated electrical energy conversion system comprises such an electrical energy converter and a control module (16) configured to receive as input a setpoint value of said electrical parameter (Vref) output from the converter and to control the variable capacitance of said capacitive circuit (14) as a function of this setpoint value. Figure for abstract: Figure 3.

Description

Title of the invention: Electrical energy converter and associated electrical energy conversion system

[0001] The present invention relates to an electrical energy converter and an associated electrical energy conversion system.

[0002] The invention generally falls within the field of electrical devices, and more particularly electrical energy converters of the power converter type.

[0003] The invention applies more particularly to power converters adapted to operate at high (2 MHz to 30 MHz) and very high frequencies (30 MHz to 300 MHz).

[0004] In particular, so-called "direct current to alternating current" or DC-AC (Direct Current-Alternative Current) electrical energy converters are known, also called inverters, adapted to operate at high and very high frequencies (30 MHz to 300 MHz).

[0005] Also known are electrical energy converters called “direct-direct”, or DC-DC, for example integrating an inverter of the type described above and an alternating-direct, or AC-DC, converter, also known as a rectifier.

[0006] In particular, there are several classes of electrical energy converters comprising a switch, typically a transistor, comprising first and second conduction terminals intended to receive an alternating voltage.

[0007] Such an electrical energy converter is intended to supply a load of real or complex impedance. For proper operation of the converter, it is necessary to perform the switching in closing of the transistor at zero voltage (in English "Zero voltage switch"), i.e. when the alternating voltage across the terminals of the transistor is substantially equal to zero. By substantially equal is meant here to within 10%, preferably to within 5%.

[0008] Conventionally, the components of the converter and the control duty cycle of the transistor are adjusted to achieve the closing of the transistor at zero voltage, for a given load impedance. In this case, any modification of the load impedance, subsequent to the adjustment, risks inducing a degraded electrical energy conversion efficiency.

[0009] Patent application FR 2106069 filed on June 9, 2021 proposes a power converter comprising a switching regulation block making it possible to automatically regulate the transistor drive duty cycle, and therefore to automatically adapt to a change in load impedance while ensuring zero voltage switching.

[0010] However, the power converter described in patent application FR 2106069 is adapted to operate for a substantially fixed power and output voltage amplitude.

[0011] More generally, known power converters are configured to operate at fixed output voltage or power, for a load to be supplied with variable or fixed impedance.

[0012] The object of the present invention is to overcome this drawback by proposing an electrical energy converter of which an electrical output parameter, and in particular the output voltage amplitude, can be regulated within a regulation range.

[0013] To this end, the invention proposes, according to one aspect, an electrical energy converter comprising an inverter making it possible to obtain alternating electrical energy from a direct electrical energy source, said inverter comprising a switch comprising first and second conduction terminals intended to receive an alternating voltage, said electrical energy converter being adapted to supply an output electrical energy to a load having a load impedance. This converter comprises a capacitive circuit of variable and controllable capacity, connected between the inverter and the load, the control of a modification of said capacity making it possible to obtain a modification of an electrical output parameter of the converter.

[0014] Advantageously, the electrical energy converter according to the invention comprises a capacitive circuit of variable and controllable / pilotable capacity, which makes it possible to carry out, on command, the regulation of an electrical output parameter of the converter.

[0015] The electrical energy converter according to the invention may also have one or more of the characteristics below, taken independently or in any technically conceivable combination.

[0016] The output parameter is an output voltage or current or power of the converter.

[0017] The converter comprises an impedance matching block configured to match an output impedance of said inverter to the load impedance, said variable capacitance capacitive circuit being connected between the impedance matching block and the load to be supplied.

[0018] The converter further comprises a rectifier block making it possible to obtain continuous electrical energy from an alternating electrical energy source, said rectifier block being connected between the capacitive circuit of variable capacity and the load to be supplied.

[0019] The converter further comprises a regulation block configured to ensure switching of the switch when the voltage between said first and second conduction terminals of said switch is substantially zero.

[0020] The capacitive circuit comprises a plurality of capacitors arranged in parallel, each capacitor being connected in series to an associated switch, said capacitor being connected in the capacitive circuit when the associated switch is in the closed position, said capacitor being disconnected from the capacitive circuit when the associated switch is in the open position, the variable capacitance of said capacitive circuit being equal, at a given instant, to the sum of the capacitances of the capacitors connected in the capacitive circuit at said given instant.

[0021] A first of said capacitors has an initial capacitance, the other capacitors each having a capacitance which is a multiple of said initial capacitance.

[0022] According to another aspect, the invention relates to an electrical energy conversion system comprising an electrical energy converter as briefly described above and an electronic module for controlling the variable capacitance capacitive circuit, configured to receive as input a setpoint value of said electrical output parameter of the converter and to control the variable capacitance of said capacitive circuit as a function of said setpoint value.

[0023] According to a variant, the control module comprises a subtractor, configured to receive, on a first input, a value of said electrical output parameter of the converter, and to receive, on a second input, the setpoint value of said electrical parameter, said subtractor being configured to calculate a difference between the value of the electrical output parameter of the converter and the setpoint value.

[0024] According to a variant, the control module further comprises a conversion module configured to transform the calculated difference into a control signal for the capacitive circuit.

[0025] Other characteristics and advantages of the invention will emerge from the description given below, for information purposes only and in no way limiting, with reference to the appended figures, among which:

[0026] [Fig-1] [Fig.l] is a schematic illustration of a system comprising a electrical energy converter according to a first embodiment;

[0027] [Fig.2] [Fig.2] is a schematic illustration of a system comprising a electrical energy converter according to a second embodiment;

[0028] [Fig.3] [Fig.3] schematically represents an embodiment of a system electrical conversion according to [Fig.2];

[0029] [Fig.4] [Fig.4] schematically and partially represents a second mode of production of a control module for an electrical energy converter;

[0030] [Fig.5] [Fig.5] is a graph representing an example of the evolution of the output voltage of an electrical energy converter comprising a capacitive circuit according to the invention.

[0031] In the following description, the term "substantially equal" defines a relationship of equality to plus or minus 10%, preferably to plus or minus 5%.

[0032] [Fig.l] schematically represents an electrical energy conversion system 2, comprising an electrical energy converter 4.

[0033] The electrical energy converter 4 is for example a DC-DC converter, called a DC-DC converter. In this case, the converter 4 comprises a rectifier, as described in more detail below.

[0034] The system 2 comprises an electrical energy source 6, providing a substantially continuous voltage Vin. The energy source 6 is for example a battery or a solar panel.

[0035] The electrical energy converter 4 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.

[0036] The electrical energy converter 4 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.

[0037] In the example of [Fig.l], the electrical energy converter 4 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.

[0038] The electrical energy converter 4 is connected to a load 8, of real or complex load impedance.

[0039] In a variant not shown, the electrical energy converter 4 is configured to deliver several distinct output voltages from one or more distinct input voltages, the number N of distinct output voltages then being greater than 1. In a further variant, the electrical energy converter 4 is configured to deliver one or more distinct output voltages from several distinct input voltages, the number E of distinct input voltages then being greater than 1. In a further variant, the electrical energy converter 4 is configured to deliver several distinct output voltages from several distinct input voltages, the numbers E and N then each being greater than 1.

[0040] When the electrical energy converter 4 is configured to deliver several distinct output voltages, the converter 4 is typically connected to several charges 8.

[0041] The electrical energy converter 4 comprises a direct-alternating or DC / AC conversion block 10, also known as an inverter.

[0042] The inverter 10 is preferably an inverter of the switch type, the switch being for example a transistor, adapted to operate at high frequency (HF) and very high frequency (VHF), typically in a frequency range from 2 MHz to 300 MHz. In this case, the electrical energy converter 4 is a VHF converter.

[0043] The transistor is, for example, an insulated gate field effect transistor, also called MOSFET (from the English Metal Oxide Semiconductor Field Effect Transistor). Alternatively, the transistor is a bipolar transistor; an insulated gate bipolar transistor, also called IGBT (from the English Insulated Gate Bipolar Transistor); a silicon (Si) based transistor, a GaN (from the English Gallium Nitride) based transistor; a silicon carbide (SiC) based transistor, or a diamond based transistor, or even a thyristor.

[0044] The inverter 10 is for example of the type comprising a piezoelectric element.

[0045] More generally, the electrical energy converter 4 operates in a similar manner with several inverter topologies, for example class E, class Phi2, class L-Piezo inverters.

[0046] For example, class E is defined in the article by NO Sokal and AD Sokal, "Class EA new class of high-efficiency tuned single-ended switching power amplifiers," published in IEEE Journal of Solid-State Circuits, vol. 10, no. 3, pp. 168-176, June 1975; class Phi2 is defined in the article by JM Rivas, Y. Han, O. Leitermann, A. Sagneri and DJ Perreault, "A High-Frequency Resonant Inverter Topology with Low Voltage Stress," published in 2007 IEEE Power Electronics Specialists Conference, 2007, pp. 2705-2717; The L-Piezo class is defined in the article by V. Massavie, G. Despesse, S. Carcouet and X. Maynard, "A new topology of resonant inverter including a piezoelectric component," published in 2021 23rd European Conference on Power Electronics and Applications (EPE'21 ECCE Europe), 2021, pp. 1-10.

[0047] The electrical energy converter 4 further comprises, in the illustrated embodiment, an impedance matching block 12, which is configured to perform an adaptation between the impedance of the load 8 and the output impedance of the inverter 10.

[0048] For example, the impedance matching block 12 is a circuit comprising real or complex passive components. Several impedance matching circuit topologies are known, for example an L-shaped topology comprising inductive and capacitive components, arranged so as to perform low-pass filtering. or high pass; a “pi” topology or a T topology.

[0049] [Fig. 3], described in more detail below, illustrates a particular embodiment in which the impedance adapter block is formed of an inductive element, for example a coil, and a capacitor (LC circuit), of low-pass type L-shaped topology.

[0050] In addition, the electrical energy converter 4 comprises a capacitive circuit 14 of variable capacity, the variation in capacity being controllable / driveable by a control module 16, advantageously making it possible to vary an electrical output parameter of the electrical energy converter by varying the capacity of the capacitive circuit 14. The electrical output parameter of the electrical energy converter 4 is for example a voltage, a current or a power.

[0051] The capacitive circuit 14 of variable capacitance is connected between the impedance matching block 12 and the load 8.

[0052] When the electrical energy converter 4 is configured to deliver several distinct output voltages to power several loads 8, the converter 4 comprises a capacitive circuit 14 of variable capacity for each load 8.

[0053] In the illustrated embodiment, the capacitive circuit 14 is connected between the impedance matching block 12 and a rectifier block 18, also forming part of the electrical energy converter 4, in the case where the electrical energy converter 4 is a DC-DC converter.

[0054] The variation of the output electrical parameter is carried out by applying to the input of the control module 16 a setpoint electrical parameter value Pref, for example a setpoint voltage Vref, or a setpoint current Iref, or a setpoint power Pref.

[0055] In another embodiment, illustrated in [Fig.2], the electrical energy conversion system 2 comprises a converter 4, which comprises, in addition to the elements described above which are referenced by the same numbers, a regulation block 20, which is configured to ensure substantially zero voltage switching or ZVS (for "zero voltage switch" in English) of the switch (eg transistor) of the inverter 10.

[0056] Indeed, advantageously, switching at substantially zero voltage causes little disturbance to the inverter 10 and generates low energy losses at the level of the inverter switch.

[0057] For example, in one embodiment, the regulation block is of the type described in patent application FR2106069, configured to perform switching at substantially zero voltage (ZVS switching).

[0058] [Fig. 3] illustrates an example of an electrical energy conversion system 22 whose elements are described in detail below.

[0059] In this particular example, the regulated output electrical parameter is voltage.

[0060] The electrical energy conversion system 22 comprises an electrical energy source 6, providing a substantially continuous voltage Vin, comprising a negative terminal (denoted -) connected to a node 24. The node 24 is a node for applying a reference potential, for example ground. The energy source 6 also comprises a positive terminal (denoted +), connected to an input node 26 of the inverter 10.

[0061] Node 26 is also connected to one terminal of an optional capacitor 28 of given capacitance Cin, which smooths the input voltage, the other terminal of capacitor 28 being connected to a node 24 for applying the reference potential.

[0062] The assembly formed by the energy source referenced 6 and the capacitor 28 forms, in the illustrated embodiment, an electrical energy source.

[0063] In the embodiment illustrated in [Fig.3], the inverter 10 is an L-piezo type inverter.

[0064] The inverter 10 comprises an inductive element, for example a coil 32, one terminal of the coil 32 being connected to the input node 26 of the inverter, the other terminal being connected to a node 34.

[0065] The piezoelectric element 36 is connected between the node 34 and a node 24 for applying the reference potential.

[0066] In the illustrated embodiment, the piezoelectric element 36 is modeled in the form of two branches connected in parallel between two terminals (or electrodes) 38 and 40, the terminal 38 being connected to the node 34 and the terminal 40 being connected to the node 24, one of the branches comprising a capacitor 42, the other branch, called the resonant branch, comprising an LC circuit formed by an inductive element, for example a coil 44, connected in series with a capacitor 46.

[0067] The term branch designates a part of an electrical circuit located between two consecutive nodes, the elements of a branch being connected in series.

[0068] The capacitance of the capacitor 42 connected in parallel with the resonant branch is called parallel capacitance, or blocked capacitance, or reference capacitance, and noted Co. The voltage across the terminals of the piezoelectric element 36 then typically corresponds to the voltage across the terminals of the capacitor 42.

[0069] The inverter 10 optionally comprises a capacitor 48, of capacitance Cr, one terminal of the capacitor 48 being connected to the node 34, the other terminal of the capacitor 48 being connected to the node 24 for applying the reference potential. The capacitance Cr is a so-called adjustment capacitance.

[0070] The switch 52 is for example a field effect power transistor or FET (from the English “Field Effect Transistor”), for example a MOSFET transistor (from the English Metal Oxide Semiconductor Field Effect Transistor).

[0071] Alternatively, the transistor is a bipolar transistor; an insulated gate bipolar transistor, also called IGBT (from the English Insulated Gate Bipolar Transistor); a silicon-based transistor (Si), a gallium nitride or GaN-based transistor (from the English Gallium Nitride); a silicon carbide (SiC)-based transistor, or a diamond-based transistor, or even a thyristor.

[0072] According to another variant, the transistor is a high electron mobility transistor (HEMT), for example based on gallium nitride GaN.

[0073] The switch 52 comprises a first conduction terminal 54d (drain), connected to the node 34, a second conduction terminal 54s (source) connected to the node 24 for applying the reference potential, and a third control terminal 54g (gate).

[0074] The control voltage Vgs has the effect of controlling the switching of the switch 52 between a closed (or on) state and an open (or off) state. When the voltage Vgs is greater than or equal to a threshold voltage, the switch 52 is in the on state, and when the voltage Vgs is less than the threshold voltage, the switch 52 is in the off state.

[0075] For example, the switch 52 of the inverter 10 has a switching frequency of between 2 MHz and 300 MHz.

[0076] The control voltage Vgs is supplied by the regulation block 20, with the aim of ensuring a closing switching of the switch 52 when the voltage Vds between the first terminal 54d (respectively node 34) and the second terminal 54s of the switch is substantially zero.

[0077] The inverter 10 further comprises another inductive element 56, for example a coil, of inductance Ls, in series with a capacitor 58, of capacitance Cs, between the node 34 and an output terminal 60 of the inverter.

[0078] A sinusoidal voltage Vch is obtained at the output of the inverter 10.

[0079] The impedance matching block 12 comprises, in the embodiment of [Fig. 3], an inductive element, for example a coil 62 of inductance La, connected between the output terminal 60 of the inverter and an output terminal 66 of the impedance matching block, and a capacitor 64, of capacitance Ca, connected to the terminal 66 and the node 24 for applying the reference potential.

[0080] Thus, in this embodiment, the impedance matching block has an L-shaped topology.

[0081] The electrical energy converter 22 further comprises a regulation block 20, which comprises, in this embodiment, a block 70 for detecting a minimum value of the voltage Vds and for averaging this voltage over several alternations, making it possible to obtain an average Va. The block 70 is connected between the node 34, connected to terminal 54d of switch 52, and an input of a subtractor 74.

[0082] The subtracter 74 has a first input (+) connected to the block 70 and a second input (-) receiving a reference potential Uref. The subtracter 74 makes a difference between the first and second inputs.

[0083] Thus, the subtractor 74 compares the average voltage Va to the reference potential U ref, the reference potential being adjusted to obtain quasi-ZVS operation.

[0084] An image signal of a difference between Va and Uref is provided at the output of the subtractor.

[0085] The output of the subtractor 74 is connected to the input of a corrector 76, the corrector 76 being, in one embodiment, a proportional-integral corrector. The corrector 76 makes it possible to obtain a more stable control loop than if the circuit 20 were without a corrector.

[0086] The output of the corrector 76 is provided as input to a pulse width modulation or PWM circuit 78, which is connected to the gate of the transistor 52 to provide the voltage control signal Vgs, which controls the switching of the transistor 52. Thus, the closing and opening times of the transistor 52 are controlled by the signal from the PWM circuit 78, itself controlled by the corrector 76, which provides a DC voltage representing a duty cycle to be applied. This signal is commonly called the “duty cycle”.

[0087] In the embodiment of [Fig. 3], the converter 22 further comprises, at the output of the impedance matching block 12, a capacitor 68 connected between the output terminal 66 and the node 24 for applying the reference potential, of predetermined capacity (fixed capacity), as well as a capacitive circuit 14 of variable capacity, controlled by a control module 16.

[0088] In the embodiment of [Fig.3], the capacitive circuit 14 comprises P=3 capacitive components, e.g. capacitors 80-1, 80-2 and 80-3 connected in parallel, with respective capacitances Cvar_1, Cvar_2, Cvar_3.

[0089] The number P of capacitors in the capacitive circuit is a chosen integer.

[0090] Each of the capacitors is connected to an associated switch 82-1, 82-2, 82-3, for example a transistor.

[0091] More generally, 80-i will designate any one of the capacitors of the capacitive circuit, and 82-i will designate the associated switch.

[0092] Note that an 80-i capacitor can be made up of any series and / or parallel association of elementary capacitors. This can be useful for obtaining precise capacity ratios between two 80-i capacitors. For example, to obtain a 80-3 capacitor equal to twice the 80-2 capacitor itself equal to twice the 80-1 capacitor, it is possible to use the same capacitor reference and use two in parallel for 80-3, only one for 80-2 and two in series for 80-1. Thus, by using the same reference, the characteristics and temperature drift will be similar.

[0093] The variable capacitance Cvar of the capacitive circuit 14 is, at a given instant, equal to the sum of the capacitances of the capacitors connected in the capacitive circuit 14.

[0094] A capacitor 80-i is connected in the capacitive circuit 14 when the switch 82-i to which it is connected, also called the associated switch, is closed, which allows the electric current to pass. When the associated switch is open, the capacitor 80-i is disconnected, and its capacitance Cvar_i does not contribute to the total capacitance of the capacitive circuit.

[0095] Thus, by controlling the opening and closing of the switches associated with the capacitors, and consequently by connecting and disconnecting the associated capacitors in the capacitive circuit, it is possible to vary the capacitance Cvar of the capacitive circuit.

[0096] In the illustrated embodiment it is possible to connect / disconnect each capacitor individually, by applying a control signal to the gate of the associated transistor. Thus, all combinations of opening / closing of the transistors are possible, which makes it possible to achieve a set of Cvar capacitance values.

[0097] For example, when the capacitive circuit comprises 3 capacitors, 8 combinations are possible.

[0098] In one embodiment, the capacitors 80-1 to 80-P (where P=3 in the example of [Fig.3]) have different capacitance values, for example increasing and following a geometric progression (or geometric sequence) of reason R, for example R=2.

[0099] By way of non-limiting example, Cvar_l=C, Cvar_2=2C, Cvar_3=4C, and more generally Cvar_p=2p 'C. For example, the capacitance value C, called initial capacitance, is equal to 120pF.

[0100] In the case where the capacitive circuit comprises P capacitors in parallel, with capacities of increasing values of C, 2C, 4C,..., 2P 'C, the control of the associated switches makes it possible to obtain total Cvar capacity values (variable capacity of the capacitive circuit) ranging from 0 to Cvar_max=(2p-l)C.

[0101] The number of capacitance value steps is 2P in this case.

[0102] Thus, the total capacity Cvar is written mathematically in the form:

[0103] CvarKjCvar i

[0104] Where K; represents the state of the switch associated with the capacitor of capacity Cvar_i, Ki=0 if the switch is open, and K;=1 if the switch is closed.

[0105] As indicated above, in one embodiment, switches 82-1 to 82-P are transistors.

[0106] For example, each switch 82-i is a power transistor with a polarization effect field or FET (from the English "Field Effect Transistor"), for example a MOSFET transistor (from the English Metal Oxide Semiconductor Field Effect Transistor).

[0107] Alternatively, the transistor is a bipolar transistor; an insulated gate bipolar transistor, also called an IGBT (Insulated Gate Bipolar Transistor), a silicon (Si)-based transistor, a gallium nitride or GaN (Gallium Nitride)-based transistor; a silicon carbide (SiC)-based transistor, or a diamond-based transistor, or a thyristor.

[0108] According to another variant, the transistor is a high electron mobility transistor (HEMT), for example based on gallium nitride GaN.

[0109] Each transistor 82-i comprises a first conduction terminal 84d-i (drain) connected to a node 86-i, a second conduction terminal 84s-i (source) connected to the node 24 for applying the reference potential, and a third control terminal 84g-i (gate).

[0110] The control voltage Vgs-i (gate source voltage between the third terminal and the second terminal) has the effect of controlling the switching of the transistor 82-i between an on state and an off state. When the voltage Vgs-i is greater than or equal to a threshold voltage of the transistor, the transistor 82-i is in the on state, and when the voltage Vgs-i is less than the threshold voltage, the transistor 82-i is in the off state.

[0111] Two embodiments of the control module 16 of the respective switching control voltages of the transistors 82-1 to 82-P will be described below.

[0112] In the embodiment of [Fig.3], the converter 22 also comprises a class E rectifier 18, which has the function of rectifying the sinusoidal voltage supplied by the inverter 10 to obtain a continuous output voltage.

[0113] In this embodiment, the rectifier block 18 comprises a block 90 comprising a diode 92 connected in parallel with a capacitor 94, the block 90 being connected between an input node 95 of the rectifier and the node 24 for applying the reference potential, an inductive element, for example a coil 96 connected between the node 95 and an output node 98 of the rectifier 18, as well as a capacitor 100, which is an output capacitor of capacitance Cout connected between the node 98 and the node 24 for applying the reference potential.

[0114] The output voltage is supplied to a load 8.

[0115] An image of the output voltage Vout is provided at the input of the control module 16 of the variable capacitance capacitive circuit.

[0116] In one embodiment, the module 16 comprises a subtractor 102, which comprises a first input (+) on which the output voltage Vout is received and a second input (-) on which a reference voltage Vref is supplied.

[0117] In other embodiments, another electrical parameter is regulated at the output, and a setpoint value of the regulated electrical parameter is provided.

[0118] The regulated electrical parameter is for example the current, and an output current value is provided on the first input of the subtractor 102, and a setpoint current value is provided on the second input of the subtractor 102.

[0119] According to a variant, the regulated parameter is the power, an output voltage value and an output current value are obtained and multiplied to obtain an output power value supplied on the first input of the subtractor 102, and a setpoint power value Pref is supplied on the second input of the subtractor 102.

[0120] In the embodiment of [Fig.3], the subtracter 102 provides as output an image of a difference between the voltage Vout and the setpoint voltage Vref, which is provided as input to a corrector 104 of the proportional, integral (PI) or proportional, integral, derivative (PID) type, or another type of corrector which delivers a control signal.

[0121] The signal is then supplied to an analog-to-digital converter 106 which converts the control signal into a digital signal whose bits address each switch 82-i.

[0122] For example, in one embodiment, the corrector 104 provides a DC voltage which is an image of the difference between the voltage Vout and the voltage Vref. The DC voltage value is converted into a digital value by the converter 106, for example coded on 3 bits. Each bit controls one of the switches 82-1, 82-2, 82-3, the least significant bit controlling the switch connected to the lowest capacitance, and so on.

[0123] [Fig. 4] is a partial schematic illustration of another embodiment of the invention. The inverter 10 is not shown, and the impedance matching block has an architecture similar to that described with reference to [Fig. 3]. The rectifier block 18 is simplified compared to that described with reference to [Fig. 3].

[0124] In this embodiment, the capacitive circuit 14 comprises P capacitors, and associated switches 82-1 to 82-P.

[0125] The control module 16 is in this embodiment an electronic digital control module, for example a microcontroller, comprising an analog-digital converter 108 which receives as input the output voltage Vout, which it converts into a digital value.

[0126] The digital electronic control module is either integrated into the electrical energy converter or external to the electrical energy converter.

[0127] The digital control electronic module 16 also comprises a subtractor module 110, which performs a subtraction between the digitized voltage value and the set voltage value Vref.

[0128] The difference DIFF between these two values is provided as input to a corrector 112, for example a PID corrector, which provides as output the control voltage values of each of the switches 82-1 to 82-P.

[0129] The value given by the module 112 being a digital value, which is coded on P bits, each bit controls one of the switches, the least significant bit controlling the switch connected to the lowest capacity, and so on.

[0130] Alternatively, another electrical output parameter, for example the output current or the output power, as well as a set value of this electrical parameter, are provided to the digital electronic control module.

[0131] [Fig.5] is a graph illustrating the output voltage Vout as a function of time, obtained as a function of the connections / disconnections of the capacitors of the capacitive circuit of [Fig.3], via the closing / opening of the associated switches.

[0132] The graph in [Fig.5] is obtained by simulating connection / disconnection over time, as indicated above the abscissa axis.

[0133] During a first period Tl, the switches are open.

[0134] During a second period T2, the first capacitor of capacitance Cvar_l is connected in the capacitive circuit, the capacitance of the capacitive circuit is equal to Cvar_l.

[0135] During a third period T3, the first capacitor of capacitance Cvar_l is disconnected and the second capacitor of capacitance Cvar_2 is connected in the capacitive circuit, the capacitance of the capacitive circuit is equal to Cvar_2.

[0136] During a fourth period T4, the first capacitor of capacitance Cvar_l and second capacitor of capacitance Cvar_2 are connected in the capacitive circuit, the capacitance of the capacitive circuit is equal to Cvar_l+Cvar_2.

[0137] During a fifth period T5, the first capacitor of capacity Cvar_l and second capacitor of capacity Cvar_2 are disconnected and the third capacitor of capacity Cvar_3 is connected in the capacitive circuit, the capacity of the capacitive circuit is equal to Cvar_3.

[0138] During a sixth period T6, the first capacitor of capacity Cvar_l and third capacitor of capacity Cvar_3 are connected in the capacitive circuit, the second capacitor of capacity Cvar_2 being disconnected, the capacity of the capacitive circuit is equal to Cvar_l+Cvar_3.

[0139] During a seventh period T7, the first capacitor of capacitance Cvar_l is disconnected and the second capacitor of capacitance Cvar_2 and third capacitor of capacitance Cvar_3 are connected in the capacitive circuit, the capacitance of the capacitive circuit is equal to Cvar_2+Cvar_3.

[0140] During an eighth period T8, the first, second and third capacitors are connected, the total capacitance being equal to Cvar_l+Cvar_2+Cvar_3.

[0141] The eight successive periods correspond to stages of increasing output voltage values, extending in this example from 14.9V to 25.7V, i.e. a variation of 10.8V.

[0142] In this example the initial capacitance Cvar_l=C=120pF, Cvar_2=2C=240pF and Cvar_3=4C=480pF.

[0143] The successive levels correspond to variable capacitance values Cvar ranging from OpF for the first period T1 to 840 pF in the eighth period T8, in increments of 120 pF per period, i.e. 120 pF for the second period, 240 pF for the third period, etc.

[0144] This embodiment of the invention is particularly advantageous, because the number of capacitors is adjustable and makes it possible to obtain a variation in equally adjustable steps.

[0145] Advantageously, to obtain a fine granularity in the variation of the output voltage values, the capacitance value C (initial capacitance) is a small value, for example of the order of 5 pF to 120 pF.

[0146] Thus, in the embodiment described, the variable capacitances of the capacitors of the capacitive circuit are: 0, C, 2C, 4C, 8C,....2P 'C, which makes it possible to obtain values of Cvar ranging from 0 to Cvar_max=(2p-l)C in increments of C.

[0147] For example, in an application case, a specification defining a regulation range of the output voltage, between a minimum voltage and a maximum voltage.

[0148] The minimum voltage allows the capacity of capacitor 68 to be calculated, and the maximum voltage indicates the capacity Cvar_max, equal to the sum of all the capacities of the capacitors in the capacitive circuit. This then allows the initial capacity C and / or the number of capacitors to be chosen.

[0149] The invention has been described above in an embodiment in which the variable capacitance capacitive circuit is produced by placing a plurality of capacitors in parallel.

[0150] In variants, the capacitive circuit comprises other types of capacitive components of controllable variable capacitance. For example, the capacitive circuit comprises a variable capacitor (or varicap) of capacitance ranging from 100pF to 200pF, which allows continuous variation of the output voltage, and more generally of the chosen output electrical parameter, over the achievable regulation range depending on the capacitance variation range.

[0151] According to another embodiment, the capacitive circuit comprises one or more adjustable MEMS (Micro Electro Mechanical System) capacitors.

[0152] The converter of the embodiment described in detail comprises an L-piezo inverter and a class E rectifier.

[0153] Nevertheless, it is clear to a person skilled in the art that the invention applies with other inverter topologies, for example class E, Phi2 class inverters.

[0154] Similarly, the invention applies with other rectifier topologies, for example class DE rectifiers.

[0155] According to another alternative, the invention also applies in DC-AC converters, to supply an alternating load without rectification. In this case, the regulated electrical parameter is the amplitude of the output voltage, or of the output current or of the output power of the converter.

[0156] Advantageously, the invention finds an application in numerous applications requiring a regulated output voltage, or a regulated output current or a regulated output power.

[0157] For example, the invention finds an application in systems for supplying electrical energy to electronic circuits from a battery or a power bus.

Claims

Claims

1. Electrical energy converter comprising an inverter (10) for obtaining alternating electrical energy from a direct electrical energy source, said inverter (10) comprising a switch (52) comprising first and second conduction terminals intended to receive an alternating voltage, said electrical energy converter being adapted to supply an output electrical energy to a load (8) having a load impedance, said converter being characterized in that it comprises a capacitive circuit (14) of variable and controllable capacity, connected between the inverter (10) and the load (8), the control of a modification of said capacity making it possible to obtain a modification of an electrical output parameter of the converter.

2. A converter according to claim 1, wherein said output parameter is an output voltage or current or power of the converter.

3. Converter according to one of claims 1 or 2, comprising an impedance matching block (12) configured to match an output impedance of said inverter (10) to the load impedance, said capacitive circuit (14) of variable capacity being connected between the impedance matching block (12) and the load (8) to be supplied.

4. Converter according to claim 3, further comprising a rectifier block (18) making it possible to obtain continuous electrical energy from an alternating electrical energy source, said rectifier block (18) being connected between the capacitive circuit (14) of variable capacity and the load to be supplied (8).

5. Converter according to one of claims 1 to 4, further comprising a regulation block (20) configured to ensure switching of the switch (52) when the voltage between said first and second conduction terminals of said switch (52) is substantially zero.

6. Converter according to one of claims 1 to 5, in which the capacitive circuit (14) comprises a plurality of capacitors (80-1, 80-2, 80-3,..., 80-P) arranged in parallel, each capacitor (80-1, 80-2, 80-3,..., 80-P) being connected in series to an associated switch (82-1, 82-2, 82-3,..., 82-P), said capacitor (80-1, 80-2, 80-3,..., 80-P) being connected in the capacitive circuit (14) when the associated switch (82-1, 82-2, 82-3,..., 82-P) is in the closed position, said capacitor (80-1, 80-2, 80-3,..., 80-P) being disconnected from the capacitive circuit (14) when the associated switch (82-1, 82-2, 82-3,..., 82-P) is in the open position, the variable capacitance of said capacitive circuit (14), being equal, at a given instant, to the sum of the capacitances of the capacitors connected in the capacitive circuit (14) at said given instant.

7. Converter according to claim 6, wherein a first of said capacitors (80-1) has an initial capacitance, the other capacitors (80-2, 80-3,...,80-P) each having a capacitance which is a multiple of said initial capacitance.

8. Electrical energy conversion system comprising an electrical energy converter according to one of claims 1 to 7 and a control module (16) configured to receive as input a setpoint value of said electrical parameter (Pref, Iref or Vref) output from the converter and to control the variable capacitance of said capacitive circuit (14) as a function of said setpoint value (Pref, Iref or Vref).

9. Electrical energy conversion system according to claim 8 wherein said control module (16) comprises a subtractor (102, 110), configured to receive, on a first input, a value of said electrical output parameter of the converter, and to receive, on a second input, the setpoint value of said electrical parameter, said subtractor (102, 110) being configured to calculate a difference between the value of the electrical output parameter of the converter and the setpoint value.

10. An electrical energy conversion system according to claim 9, wherein said control module (16) further comprises a conversion module (104,112) configured to transform the calculated difference into a control signal of the capacitive circuit.

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