Electronic device and method for controlling, with control via synchronized triangular signal, an electrical energy converter comprising a resonator, associated electrical energy conversion system

Abstract

Electronic device and method for controlling, with control via synchronized triangular signal, an electrical energy converter comprising a resonator, associated electrical energy conversion system The invention relates to a device (20) for controlling a converter (10) from an input voltage (Vin) to an output voltage (Vout), comprising a resonator (12) having an oscillation frequency and successive resonance cycles, and several switches (14) connected to the resonator.The control device comprises: - a module (40) for measuring a regulation quantity representative of the resonator; - a module (44) for controlling a switching of the switches, following several phases during a resonance cycle, each phase resulting from the closing of at least one switch and the opening of the other switches; - a module (42) for generating a reference triangular signal, synchronized regularly with the regulation quantity, a characteristic quantity of said triangular signal depending on the oscillation frequency of the resonator (12); the control module (44) controlling at least one of the switches from a comparison with the reference signal. Figure for the abstract: Figure 1.

Description

Title of the invention: Electronic device and method for controlling, with control via synchronized triangular signal, an electrical energy converter comprising a resonator, associated electrical energy conversion system

[0001] The present invention relates to an electronic device for controlling an electrical energy converter capable of converting an input voltage into an output voltage.

[0002] The invention also relates to an electrical energy conversion system comprising such a converter and such an electronic device for controlling the converter.

[0003] The invention also relates to a method for controlling such a converter.

[0004] A converter is known comprising two input terminals for receiving the input voltage, two output terminals for delivering the output voltage, a resonator, and several switches connected to the resonator, the resonator resonating following successive resonance cycles, each resonance cycle having a duration equal to a resonance period, the resonance period being equal to the inverse of an oscillation frequency of the resonator.

[0005] An electronic control device is known comprising a measurement module configured to measure a regulation quantity, the regulation quantity being a quantity representative of the resonator; and a control module configured to control, via a control unit, a switching of each of the switches, following several successive phases during a resonance cycle of the resonator, each phase resulting from the closing of at least one respective switch and / or the opening of at least one switch.

[0006] The most interesting feature of this type of converter is its high power density when operating at a few MHz. This is due to the mechanical and piezoelectric property of the transient energy storage element, which allows its size to be reduced substantially linearly with the increase in the converter drive frequency, while the inductance shows a reduction with a lower rate, as described in the article by PA Kyaw and CR Sullivan, "Fundamental examination of multiple potential passive component technologies for future power electronics" 2015 IEEE 16th Workshop on Control and Modeling for Power Electronics (COMPEL).

[0007] Control strategies, i.e. piloting, of direct-to-direct or DC-DC converters (from the English Direct Current-Direct Current) with piezo resonator- six-phase electric current during a resonance cycle, with alternation of phases at substantially constant voltage across the terminals of the resonator and phases at substantially constant charge across the terminals of said resonator, are described in the following articles:

[0008] - JJ Piel, JD Boles, JH Lang and DJ Perreault, "Feedback Control for a Pie- zoelectric-Resonator-Based DC-DC Power Converter" 2021 IEEE 22nd Workshop on Control and Modeling of Power Electronics (COMPEL);

[0009] - B. Pollet, G. Despesse and F. Costa, "A New Non-isolated Low-Power Inductorless Piezoelectric DC-DC Converter" in IEEE Transactions on Power Electronics, vol. 34, no. 11; and

[0010] - M. Touhami, G. Despesse, F. Costa and B. Pollet, “Implementation of Control Strategy for Step-down DC-DC Converter Based on Piezoelectric Resonator" 2020 22nd European Conference on Power Electronics and Applications (EPE'20 ECCE Europe).

[0011] However, these strategies use digital control carried out via a microcontroller, or a programmable logic component, such as an FPGA (Field Programmable Gate Array), or a configurable logic block, also called CLB (Configurable Logic Block), which has certain limitations.

[0012] The maximum operating frequency of the controlled converters is limited by the sampling frequency and precision of the controller used (for example, the most commonly used FPGA cards, such as Altéra cyclone V, have a limitation of the maximum frequency of an analog input signal of approximately 1 MHz, which restricts the sampling time resolution of the input signal to a maximum of 4 ns).

[0013] Direct control of switch control units, i.e. measuring the reference voltage and acting directly through a comparator used at 100 kHz, is not possible at a frequency of 10 MHz due to the delays of the control units (which are longer than the typical duration of a resonance cycle phase). Each control unit is capable of applying a control signal to a control electrode, such as a gate electrode, of the associated switch, such as a transistor.

[0014] The miniaturization of the converter is limited by the size of the controller, which can be larger than that of the resonator and its power switches. However, microcontrollers or FPGAs have the advantage of being more flexible, allowing adaptations of the controller through programming. Unlike the integrated circuit, microcontrollers or FPGAs can be reprogrammed to make functional changes after its start-up.

[0015] The aim of the invention is then to propose an electronic control device, and an associated control method, allowing improved control of the electrical energy converter.

[0016] For this purpose, the invention relates to an electronic device for controlling an electrical energy converter capable of converting an input voltage into an output voltage, the converter comprising two input terminals for receiving the input voltage, two output terminals for delivering the output voltage, a resonator, and several switches connected to the resonator, the resonator resonating following successive resonance cycles, each resonance cycle having a duration equal to a resonance period, the resonance period being equal to the inverse of an oscillation frequency of the resonator;

[0017] the electronic control device comprising:

[0018] - a measurement module configured to measure a regulation quantity, the regulation quantity being a quantity representative of the resonator;

[0019] - a control module configured to control, via a control unit, a switching of each of the switches, following several successive phases during a resonance cycle of the resonator, each phase resulting from the closing of at least one respective switch and the opening of the other switches;

[0020] - a generation module configured to generate a reference triangular signal, regularly synchronized with the control quantity, a characteristic quantity of the reference triangular signal depending on the oscillation frequency of the resonator;

[0021] the control module being configured to control at least one of the switches from a comparison with the reference signal.

[0022] With the electronic control device according to the invention, the reference triangular signal makes it possible to precisely control the periodic control instants of the switches, and this in a manner synchronized with the regulation quantity which is representative of the resonator, the regulation quantity typically being the voltage across the terminals of the resonator.

[0023] Furthermore, the slope of the reference triangular signal depends on the oscillation frequency of the resonator, and is typically proportional to this oscillation frequency, i.e. vibration, of the resonator, which then makes it possible to have switch switchings synchronized with the resonance of the resonator.

[0024] The triangular signal then makes it possible to carry out a time-to-quantity conversion where the quantity, such as a voltage, is that of the reference signal, in order to associate with each periodic control instant a corresponding value of the quantity on the triangular signal.

[0025] This improved precision then makes it possible to minimize switching losses and maintain soft switching conditions, especially zero voltage or ZVS (Zero Voltage Switching), which allows the converter to operate optimally at high frequencies.

[0026] According to other advantageous aspects of the invention, the electronic control device comprises one or more of the following characteristics, taken in isolation or in all technically possible combinations:

[0027] - the generation module is configured to synchronize the reference signal with the control quantity at least once per resonance cycle;

[0028] - the regulation quantity is a voltage across the terminals of the resonator;

[0029] the reference signal preferably being a triangular voltage;

[0030] - the reference triangular signal is periodic and in the form of a ramp at each period ;

[0031] the ramp having a period, called the ramp period, the ramp period preferably being equal to the resonance period, the ramp period then being equal to the inverse of the oscillation frequency of the resonator;

[0032] - a time instant of the start of the period of the reference signal is determined in function of the control quantity;

[0033] the time instant of the start of the period preferably depending on a time instant at which the time derivative of the regulation quantity is zero;

[0034] - the time instant of the start of the period is anticipated relative to a time instant switching of a corresponding switch, a time difference between the time instant of the start of the period and the switching time instant depending on a processing delay by the control unit, from the emission of a switching command until the switching of the switch;

[0035] - the characteristic quantity is chosen from the group consisting of: a slope of the reference triangular signal and an amplitude of the reference triangular signal;

[0036] - when the characteristic quantity is the slope of the reference triangular signal, the slope of the ramp is proportional to the oscillation frequency of the resonator; the ramp preferably having a fixed amplitude; the slope of the ramp preferably varying further as a function of the oscillation frequency of the resonator when the amplitude of the ramp is fixed;

[0037] when the characteristic quantity is the amplitude of the reference triangular signal, the amplitude is inversely proportional to the oscillation frequency of the resonator; the ramp preferably having a fixed slope; the amplitude of the ramp preferably varying further as a function of the oscillation frequency of the resonator when the slope is fixed;

[0038] - the control module is configured to control several switches at the following one another, corresponding to several phases of the resonance cycle, each command being carried out from a respective comparison with the reference signal;

[0039] - the control module is configured to control each switch in one respective control instant, obtained by comparing a control signal with the reference signal, and each switch is associated with at least one respective control signal;

[0040] a minimum stop and a maximum stop being predefined for each control signal, the minimum and maximum stops defining minimum and maximum values ​​of the control instant;

[0041] the control signal and the reference signal preferably being voltages, and the minimum and maximum stops then being minimum and maximum voltages;

[0042] - the switches include:

[0043] + a first switch connected between one of the input terminals and the resonator, the first switch being switchable between an open position and a closed position in which the input voltage is applied across the resonator;

[0044] + a second switch connected to the terminals of the resonator, the second in switch being switchable between an open position and a closed position in which the voltage is zero across the resonator; and

[0045] + a third switch connected between one of the output terminals and the resonator, the third switch being switchable between an open position and a closed position in which energy from the resonator is returned to the output voltage.

[0046] - the resonator is a piezoelectric resonator;

[0047] the piezoelectric resonator preferably being constituted according to one of the constitutions among the group consisting of: a single piezoelectric element; several piezoelectric elements connected in series; several piezoelectric elements connected in parallel; a piezoelectric element and an auxiliary capacitor connected in series; a piezoelectric element and an auxiliary capacitor connected in parallel; and an arrangement of several parallel branches, each branch comprising one or more piezoelectric elements connected in series or an auxiliary capacitor;

[0048] the auxiliary capacitor preferably being of greater capacity, more preferably at least three times greater, than a reference capacity of the piezoelectric element(s), each piezoelectric element being modeled in the form of a capacitor and a resonant branch connected in parallel to the capacitor, the reference capacity being the capacity of said capacitor;

[0049] - the control module is configured to control the switching of each switches for alternating phases with substantially constant voltage across the terminals of the piezoelectric resonator and phases with substantially constant charge across the terminals of said piezoelectric resonator; and

[0050] - the resonator is an LC resonator comprising an inductor and a capacitor connected in series of the inductance.

[0051] The invention also relates to an electrical energy conversion system comprising:

[0052] - an electrical energy converter capable of converting an input voltage into a output voltage, the converter comprising two input terminals for receiving the input voltage, two output terminals for delivering the output voltage, a resonator, and several switches connected to the resonator, the resonator resonating following successive resonance cycles, each resonance cycle having a duration equal to a resonance period, the resonance period being equal to the inverse of an oscillation frequency of the resonator; and

[0053] - an electronic device for controlling the electrical energy converter; the electronic control device being as defined above.

[0054] The invention also relates to a method for controlling an electrical energy converter capable of converting an input voltage into an output voltage, the converter comprising two input terminals for receiving the input voltage, two output terminals for delivering the output voltage, a resonator, and several switches connected to the resonator, the resonator resonating following successive resonance cycles, each resonance cycle having a duration equal to a resonance period, the resonance period being equal to the inverse of an oscillation frequency of the resonator;

[0055] the method being implemented by an electronic control device and comprising the following steps:

[0056] - measurement of a regulation quantity, the regulation quantity being a quantity representative of the resonator;

[0057] - control, via a control unit, of a switching of each of the switches breakers, following several successive phases during a resonance cycle of the resonator, each phase resulting from the closing of at least one respective switch and the opening of the other switches,

[0058] - generation of a reference triangular signal, regularly synchronized with the control quantity, a characteristic quantity of the reference triangular signal depending on the oscillation frequency of the resonator;

[0059] the control of at least one of the switches being carried out from a comparison with the reference signal.

[0060] 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:

[0061] [Fig.l] [Fig.l] is a schematic representation of an electronic electrical energy conversion system according to the invention, comprising an electrical energy converter comprising a resonator and several switches connected to the resonator; and an electronic device for controlling the electrical energy converter; the resonator being a piezoelectric resonator;

[0062] [Fig.2] [Fig.2] is a schematic representation of the energy converter electric when the resonator is an LC resonator;

[0063] [Fig.3] [Fig.3] is a schematic representation of the control device of the [Fig.l];

[0064] [Fig.4] [Fig.4] is a schematic view of a ramp generator;

[0065] [Fig.5] [Fig.5] is a flowchart of a method, according to the invention, of piloting of the electrical energy converter, the method being implemented by the electronic control device of [Fig.l];

[0066] [Fig.6] [Fig.6] represents curves of the voltage and the intensity at the terminals of the piezoelectric resonator of [Fig.l], in voltage-boosting mode, and respectively in voltage-down mode, of the electrical energy converter; and

[0067] [Fig.7] [Fig.7] represents on the left the curve of the voltage and the intensity at the terminals of the piezoelectric resonator in voltage step-down mode of [Fig.l], in a manner analogous to [Fig.6]; and on the right the curve of a reference triangular signal used for controlling the switches.

[0068] In [Fig.l], an electronic electrical energy conversion system 5 comprises an electrical energy converter 10 comprising a resonator 12 and several switches 14 connected to the resonator 12. In the example of [Fig.l], the resonator 12 is a piezoelectric resonator 15, the switches 14 are denoted Kl, K2, K3. In the example of [Fig.2], the resonator 12 is an LLC resonator 18, the switches 14 are denoted S1, S2, S3, S4.

[0069] The conversion system 5 also comprises an electronic device 20 for controlling the electrical energy converter 10. The electrical energy is typically a voltage, or alternatively a current or a power.

[0070] The electronic electrical energy conversion system 5 is typically a system for converting into direct electrical energy, such as a direct-to-direct conversion system capable of converting a first direct electrical energy received at the input into a second direct electrical energy delivered at the output, or even an alternating-to-direct conversion system capable of converting alternating electrical energy received at the input into direct electrical energy delivered at the output of the conversion system 5.

[0071] 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 alternating 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 into another DC electrical energy. 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.

[0072] Those skilled in the art will observe that these different examples for the conversion system 5, whether it is a DC-DC conversion system or an AC-DC conversion system, are also presented in the documents FR 3 086 471 A1 and FR 3 086 472 A1, in particular with regard to their figures 1 to 3, 10, 15, 17 and 19 to 20.

[0073] 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 Vout of a load 22 to a stable value, by being powered by an energy source 24 providing a substantially DC voltage Vin. The energy source 24 is for example a battery or a solar panel.

[0074] 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 step-up DC-DC converter, or a high-step-up DC-DC converter; or is configured to lower the value of the DC voltage between its input and its output, and is then called a step-down DC-DC converter, with also a variant of a high-step-down DC-DC converter.

[0075] When the electrical energy converter 10 is a step-down DC-DC converter, the value of the input voltage typically corresponds to the voltage Vin of the energy source 24, and the value of the output voltage corresponds to the voltage Vout across the terminals of the load 22, the voltage Vin then being greater than the voltage Vout.

[0076] When the electrical energy converter 10 is a DC-DC step-up converter, the value of the input voltage also typically corresponds to the voltage Vin of the energy source 24, and the value of the output voltage corresponds to the voltage V out at the terminals of the load 22, the voltage Vin then being lower than the voltage V out.

[0077] When the electrical energy converter 10 is a strongly step-down DC-DC converter, the value of the input voltage corresponds for example to the voltage difference (Vin-Vout), and the value of the output voltage corresponds for example to the voltage Vout, the voltage difference (Vin-Vout) being significantly higher at voltage Vout.

[0078] When the electrical energy converter 10 is a step-down DC-DC converter, according to a step-down variant, the value of the input voltage corresponds for example to the voltage difference (Vin-Vout), and the value of the output voltage corresponds to the voltage Vout across the terminals of the load 22, the voltage difference (Vin-V out) being greater than the voltage Vout.

[0079] The converter 10 comprises several switches 14 capable of being controlled to alternate phases at substantially constant voltage and phases at substantially constant load at the terminals of the resonator 12. This alternation of phases at substantially constant voltage and phases at substantially constant load is typically carried out within periods of substantially constant duration corresponding to the operating frequency of the converter 10, depending on an oscillation frequency, also called natural frequency or vibration frequency, of the resonator 12. The phases at substantially constant load make it possible, in steady state or permanent operation, 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 switching (from the English Zero Voltage Switching).

[0080] Each switch 14 comprises for example a transistor and an antiparallel diode (not shown) intrinsic to the transistor.

[0081] 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 a thyristor, or a mechanical switch, such as a MEMS (from the English MicroElectroMechanical System) micro-switch.

[0082] By substantially constant charge, we mean an exchange of a charge with the outside which is less than 30% 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, we mean a variation in charge less than 30% of the charge which would have been exchanged with the outside of the resonator 12 if the voltage across the terminals of the resonator 12 had been kept constant over the time period considered.

[0083] By substantially open electrical circuit, we mean a circuit in which a possible leakage current leads to a variation in charge of the resonator 12 of less than 30% of the charge which would have been exchanged with the exterior of the resonator 12 if the voltage at the terminals of the resonator 12 had been kept constant over the time duration considered.

[0084] By substantially constant voltage, we mean 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.

[0085] In the example of [Fig. 1], the control device 20 is configured to operate the piezoelectric material of the piezoelectric resonator 15 at its 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 oscillation frequency of the piezoelectric resonator 15, and by adjusting the durations of the respective switching phases within the resonance cycle.

[0086] As known per se, the mechanical oscillation of the piezoelectric resonator 15 is approximately sinusoidal. An increase or decrease in the energy stored over a period leads respectively to an increase or decrease in the oscillation amplitude.Furthermore, during a phase with substantially constant charge at the terminals of the piezoelectric resonator 15, that is to say when the piezoelectric resonator 15 is placed in a substantially open electrical circuit, with a low exchange of electrical charges between the piezoelectric resonator 15 and the exterior, 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 resonator 15, and during a phase with substantially constant voltage at the terminals of the piezoelectric resonator 15, this increase in oscillation amplitude leads to an increase in the current exchanged between the piezoelectric resonator 15 and the exterior.

[0087] In the example of [Fig. 1], a first switch Kl is connected between one of the input terminals and the piezoelectric resonator 15, the first switch Kl being switchable between an open position and a closed position in which the input voltage Vin is applied to the terminals of the piezoelectric resonator 15.

[0088] A second switch K2 is connected across the piezoelectric resonator 15, the second switch K2 being switchable between an open position and a closed position in which the voltage is zero across the piezoelectric resonator 15.

[0089] A third switch K3 is connected between one of the output terminals and the re piezoelectric resonator 15, the third switch K3 being switchable between an open position and a closed position in which energy from the piezoelectric resonator 15 is restored to the output voltage Vout.

[0090] The oscillation frequency is the frequency at which the resonator 12, such as the piezoelectric resonator 15, oscillates and consequently its current IL on its motional branch (RLC branch) of its equivalent model around the selected resonance mode. The current IL can be deduced either by observing the evolution of the voltage Vp when the resonator is isolated or by observing its output current Ip during the constant voltage phases. The conversion cycle is synchronized with a mechanical movement of the piezoelectric resonator 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 steps and the output current.Depending on the operating point, this oscillation frequency typically varies between the so-called series resonance frequency of the piezoelectric (cos=l / 'V(LC) where L and C correspond to the inductance and capacitance of a resonant branch 25 described below) and the so-called parallel resonance frequency of the piezoelectric (cop=l / 'V(L*C*Cp / (C+Cp))), also respectively called resonance frequency and antiresonance frequency of the piezoelectric resonator 15. The operating frequency of the converter 10 is then between these two resonance and antiresonance frequencies of the piezoelectric resonator 15. The operating point varies slowly with respect to the oscillation frequency of the piezoelectric resonator 15. The operating point typically varies at less than 10kHz, while the oscillation frequency of the piezoelectric resonator 15 is typically greater than or equal to 100kHz.As a result, the operating frequency of the converter 10 changes little from one period to the next.

[0091] Furthermore, the lower the output current, the closer the oscillation frequency is to the resonance frequency of the piezoelectric and the higher the output power, the closer the oscillation frequency is to the antiresonance frequency of the piezoelectric.

[0092] Generally, the total number of phases at substantially constant voltage during a resonance cycle is greater than or equal to one in a nominal operating mode of the converter 10.

[0093] In the example of [Fig.l] where the resonator 12 is the piezoelectric resonator 15, this total number of phases at substantially constant voltage is equal to three in nominal operating mode of the converter 10. Generally speaking, when the resonator 12 is the piezoelectric resonator 15, the total number of phases at substantially constant voltage during a resonance cycle is typically greater than or equal to three.

[0094] In the example of [Fig.2] where the resonator 12 is the LLC resonator 18, the total number of phases at substantially constant voltage is equal to two in the nominal operating mode of the converter 10. Generally, when the resonator 12 is the LLC resonator 18, the total number of phases at substantially constant voltage during a resonance cycle is typically greater than or equal to two. The two phases at substantially constant voltage typically correspond to +Vin and -Vin; or +Vin / 2 and -Vin / 2, where Vin represents the input voltage of the converter 10.

[0095] When in a variant not shown, the resonator 12 is the VHF type LC resonator, there is typically a single phase at substantially constant voltage in the nominal operating mode of the converter 10, and the converter 10 then typically comprises a single switch 14.

[0096] The piezoelectric resonator 15 is known per se, and is typically modeled, close to the resonance mode used, in the form of a capacitor Cp and the resonant branch 25 connected in parallel with the capacitor Cp, the capacitor Cp and the resonant branch 25 being connected between first 26 and second 27 electrodes of the piezoelectric resonator 15. The first 26 and second 27 electrodes form the terminals of the piezoelectric resonator 15.

[0097] In the example of [Fig.l], the piezoelectric resonator 15 comprises a single piezoelectric element.

[0098] In a variant not shown, the piezoelectric resonator 15 comprises several piezoelectric elements connected in series. Alternatively, the piezoelectric resonator 15 comprises several piezoelectric elements connected in parallel. Alternatively, the piezoelectric resonator 15 comprises a piezoelectric element and an auxiliary capacitor connected in series. Alternatively, the piezoelectric resonator 15 comprises a piezoelectric element and an auxiliary capacitor connected in parallel. As a further variant, the piezoelectric resonator 15 comprises an arrangement of several parallel branches, each branch comprising one or more piezoelectric elements connected in series or an auxiliary capacitor.

[0099] According to the variants concerned, the auxiliary capacitor is advantageously of greater capacity, more preferably at least three times greater, than a reference capacity of the piezoelectric element(s), such as the capacity of the capacitor Cp in the example of [Fig.l], each piezoelectric element being modeled in the form of a capacitor and a resonant branch connected in parallel with the capacitor, the reference capacity being the capacity of said capacitor.

[0100] In the example of [Fig.l], the first switch Kl is connected between a positive input terminal and the first electrode 26 of the resonator 15, the second switch K2 is connected between the first 26 and second 27 electrodes of the piezoelectric resonator 15, and the third switch K3 is connected between the first electrode 26 of the resonator 15 and a positive output terminal and the resonator 15. By positive terminal, the person skilled in the art will understand that it is the terminal of positive polarity, that is to say which is at the highest potential of the input voltage Vin, respectively of the output voltage Vout. In the example of [Fig.l], the negative input and output terminals are connected to an electrical ground GND.

[0101] The resonant branch 25 is typically an RLC branch formed of an auxiliary capacitor, a resistor and an inductor connected in series (not shown). The voltage Vp across the terminals of the piezoelectric resonator 15 then typically corresponds to the voltage across the capacitor Cp.

[0102] The capacity of the auxiliary capacitor is advantageously greater than the capacity of the capacitor Cp, in particular at least three times greater.

[0103] In the example of [Fig.2], the resonator 12 is the LLC resonator 18, and the converter 10 then forms an LLC resonant converter. The switches 14 are denoted S1, S2, S3, S4.

[0104] The LLC resonant converter comprises a switching circuit 30, an LLC resonator 18 and a rectifier 32.

[0105] The switching circuit 30 is, for example, in the form of a full bridge, also called an H-bridge, as seen in [Fig.2], or a half-bridge (not shown). The switching circuit 30 receives the voltage Vin as input.

[0106] The switching circuit 30, in its H-bridge form, comprises for example four transistors 34 forming the switches 14, also denoted S1, S2, S3, S4. The transistors 34 are for example MOSFET transistors, such as N-type depletion MOSFET transistors.

[0107] The LLC resonator 18 is connected to the output of the switching circuit 30, and is capable of receiving a voltage signal Vcm as input. The LLC resonator 18 comprises two inductors L and a capacitor C connected according to a known arrangement to form the LLC resonator. Advantageously, the LLC resonator 18 further comprises a transformer 36, connected to the output of the LLC arrangement and capable of delivering a voltage Vu. Those skilled in the art will observe that the inductance L parallel to the input of the transformer is all or part formed by the magnetizing inductance of the transformer and the inductance L in series is formed by all or part of the leakage inductance of the transformer. Those skilled in the art will also observe that the two inductances L are not necessarily identical and of the same value.

[0108] The rectifier 32 is connected to the output of the LLC resonator 18, and then able to receive the voltage Vu as input. The rectifier 32 is configured to rectify an alternating voltage into the direct voltage Vout at the output. In the example of [Fig.2], the rectifier 32 is in the form of a diode bridge 38, such as a four-diode bridge 38.

[0109] The control device 20 is configured to control the energy converter electrical 10, and in particular the switching of the switches 14 of the energy converter.

[0110] In the example of [Fig.3], the control device 20 comprises a measurement module 40, a generation module 42 and a control module 44 for a respective switch 14.

[0111] Advantageously, the control device 20 comprises a measurement module 40 and a control module 44 for each of the respective switches 14, the generation module 42 then being common to all the switches 14. In other words, in the example of [Fig.l] where the energy converter 10 comprises three switches 14, the control device 20 then advantageously comprises the generation module 42 and three control assemblies, namely a control assembly for each respective switch 14, each control assembly comprising a respective measurement module 40 and a control module 44. For the control of a respective switch 14, the associated control assembly advantageously comprises a single measurement module 40 and a single control module 44; and for the control of this respective switch 14, the generation module 42 is then connected to only these measurement 40 and control 44 modules.

[0112] More generally, the control device 20 comprises several control assemblies, and the number of control assemblies is equal to the number of switches 14 whose switching is controlled by the control device 20. The number of measurement modules 40 and the number of control modules 44 are then each equal to the number of switches 14 controlled by the control device 20. The control device 20 preferably comprises a single generation module 42, connected to each of the control assemblies.

[0113] The measurement module 40, the generation module 42, and the control module 44 are for example each produced in the form of an electronic circuit comprising one or more electronic components, and in particular comparators when comparisons are carried out.

[0114] Alternatively, the measurement module 40, the generation module 42, and the control module 44 are each 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. As a further alternative, the measurement module 40, the generation module 42 and the control module 44 are implemented together within a single hardware component, such as a single programmable logic component, a single integrated circuit, or a single computer.

[0115] The measurement module 40 is configured to measure a regulation quantity Greg. The regulation quantity Greg is for example the voltage Vp across the terminals of the resonator 12. Alternatively, the regulation quantity Greg is another quantity representative of the resonator 12, such as the current Ip.

[0116] The control quantity is preferably measured just before switching the switch 14. For example, the control quantity is measured less than 20 ns, advantageously less than 2 ns before switching on the respective switch 14.

[0117] The generation module 42 is configured to generate a reference triangular signal 45, for subsequent use in controlling the respective switch 14.

[0118] Advantageously, the reference signal 45 is a periodic triangular voltage Vramp forming a ramp at each resonance cycle of the resonator 12.

[0119] The ramp formed by the triangular voltage Vramp has a ramp period Tramp, the ramp period Tramp being preferably equal to the resonance period, the ramp period Tramp then being equal to the inverse of the oscillation frequency of the resonator 12.

[0120] A time instant of start of period of the reference signal is typically determined as a function of the regulation quantity Greg.

[0121] The time instant of the start of the period of the reference signal preferentially depends on a time instant at which the time derivative of the regulation quantity Greg is zero. When the regulation quantity Greg is the voltage Vp across the terminals of the resonator 12, the time instant at which the time derivative of the regulation quantity Greg is zero then corresponds to the zero crossing of the current IL flowing in the resonator 12, the time derivative of the voltage Vp being an image of said current IL.

[0122] Advantageously, the period start time instant is anticipated with respect to a switching time instant h of a corresponding switch, a time difference between the period start time instant and the switching time instant h depending on a processing delay by a control unit 58 of the respective switch 14, described below, i.e. the processing delay from the transmission of a switching command until the switching of the switch 14.

[0123] According to this advantageous aspect, the ramp is advanced by the delay of the control of the switching of the respective switch 14. In other words, the ramp is ahead of the switching of the respective switch 14. This gives agility to all the regulations to compensate for the control delay, i.e. the implementation delay of the control unit 58, assuming that the control delays are substantially identical from one switch 14 to another.

[0124] The reference triangular signal 45 has a characteristic quantity Gcar depending on the oscillation frequency of the resonator 12, the characteristic quantity G car being chosen from the group consisting of: a slope a of the reference triangular signal 45 and an amplitude Amp of the reference triangular signal 45.

[0125] The control module 44 is configured to control each switch 14 as a function of the reference triangular signal 45, in particular from a comparison with the reference triangular signal 45.

[0126] In the example of [Fig.3], the generation module 42 comprises a derivation unit 46, a sampling unit 48, a differential unit 50, a corrector 52 and a ramp generator 54.

[0127] The generation module 42 is connected to the output of the measurement module 40, and capable of receiving as input the regulation quantity Greg, such as the voltage Vp at the terminals of the resonator 12. In addition, the generation module 42 is capable of receiving a reset command and a value of a sampling instant t^ of the respective switch 14 which is controlled by the control device 20.

[0128] The derivation unit 46 is typically configured to calculate the derivative of an input signal, namely the regulation quantity Greg, such as the voltage Vp across the terminals of the resonator 12, and by calculating its time derivative, to deliver a voltage Vder representative of said time derivative.

[0129] The voltage Vder is typically an image of the current IL circulating in the resonator 12, being directly proportional to the value of the current IL when the regulation quantity Greg is the voltage Vp and the voltage Vder then corresponds to dVp / dt and considering that the resonator 12 is in open circuit during sampling.

[0130] The sampling unit 48 is connected to the output of the derivation unit 46 and to the control module 44, and is then able to receive as input the voltage Vder and the sampling instant tsa, advantageously less than 20 ns, advantageously substantially 1 ns to 2 ns, before the actual switching of the respective switch 14.

[0131] The sampling unit 48 is typically configured to choose a sampling duration, for example substantially equal to 1% of the total duration of a cycle.

[0132] For example, the sampling time tsa is adjustable via a programmable time delay, for example integrated on the electronic circuit forming the generation module 42, the time reference typically being a rising or falling signal edge upstream or inside the control unit 58 of the respective switch 14.

[0133] The sampling unit 48 is capable of delivering a voltage Vsa corresponding to the voltage Vder sampled at the sampling instant tsa.

[0134] The differential unit 50 is connected to the output of the sampling unit 48, and is then able to receive as input the voltage Vsa and a reference voltage Vcons.

[0135] The setpoint voltage Vcons advantageously corresponds to the desired setpoint value of the current at the sampling instant tsa, such as the value 0 for the instant to in the example described below with reference to Figures 6 and 7.

[0136] The differential unit 50 is intended to deliver a voltage Vsa' resulting from the difference between the voltages Vsa and Vcons.

[0137] The differential unit 50 is for example in the form of a subtractor, capable of subtracting the setpoint voltage Vcons from the voltage Vsa to deliver the resulting voltage Vsa'.

[0138] The corrector 52 is connected to the output of the differential unit 50, and is then able to receive the voltage Vsa' as input.

[0139] The corrector 52 is typically configured to perform a regulation of the periodic switching control instant of the respective switch 14, by receiving as input the voltage Vsa' from the sampling unit 48, by calculating an error e between this voltage Vsa' and a target voltage, and then by performing an integration of this error e. The corrector 52 is then able to deliver a voltage VM.

[0140] The corrector 52 comprises for example an operational amplifier 52A, a resistor 52B and a feedback loop with a capacitor 52C. The feedback loop connects the output of the operational amplifier 52A to its negative input. The electrical resistor 52B is connected between the input of the corrector 52 receiving the voltage Vsa' and the negative input of the operational amplifier 52A. Of course, any other type of corrector can be used, for example proportional-integral or proportional-integral-derivative.

[0141] The ramp generator 54 is connected to the output of the corrector 52, and is configured to generate the triangular voltage Vramp forming a ramp for controlling the respective switch 14, namely a control reference for all the switching times of the switches 14, the characteristic quantity Gcar, such as the slope a of the ramp, being adapted as a function of the value of the output voltage VM of the corrector 52.

[0142] The ramp generator 54 is for example intended to adjust the value of the slope a of the triangular voltage Vramp in order to regulate all switching instants; and to reset the ramp of the triangular voltage Vramp to zero.

[0143] In this example, the slope a is therefore modified as a function of the oscillation frequency of the resonator 12, while keeping the amplitude Amp of the triangular voltage Vramp constant.

[0144] Alternatively, the ramp generator 54 is intended to adjust the value of the amplitude Amp of the triangular voltage Vramp in order to regulate all switching instants. According to this alternative, the amplitude Amp is therefore modified as a function of the oscillation frequency of the resonator 12, while keeping the slope a of the triangular voltage Vramp constant.

[0145] An exemplary embodiment of the ramp generator 54 is described below with reference to [Fig.4].

[0146] In the example of [Fig.3], the control module 44 comprises a comparator 56 and the control unit 58.

[0147] The control module 44 is connected to the output of the generation module 42, and then able to receive the voltage Vramp as input.

[0148] The comparator 56 is connected to the output of the ramp generator 54, and is then able to receive the voltage Vramp.

[0149] Advantageously, there are as many control modules 44 as there are switches 14, that is to say half of the desired switching times during the resonance cycle, each switch 14 being switched once to closing and once to opening during the resonance cycle. Each of these switching times is denoted ti, i being between 0 and 6 in the example described.

[0150] Each switching instant fest is associated with a respective control signal. In the example described, each switching instant f is associated with a respective control voltage Vti.

[0151] In the example described, each switch 14 is associated with two switching times h, and then each switch 14 is associated with two respective control signals.

[0152] Each control voltage Vti is advantageously between a minimum stop Vti min and a maximum stop Vti max, the minimum stops Vti min and maximum Vti_max being predefined by the user and defining minimum values ​​ti min and maximum values ​​ti max of the control instants L

[0153] The minimum Vti min and maximum Vti max stops are intended to avoid excessively large switching offsets.

[0154] Preferably, it is observed that the maximum stop Vti max of a current switching instant h is always less than the minimum stop Vti+i_min of a following switching instant ti+i, so that the current instant t; precedes the following instant t i+i-

[0155] In the example described, the comparator 56 is intended for several uses depending on whether the duration of the resonance cycle and an initial switching instant t0 or depending on whether the following switching instants t1 to t5 are controlled. Those skilled in the art will then understand that the user associated with the comparator 56 depends on the control module 44 to which said comparator 56 belongs, then on the respective switch 14 with which it is associated.

[0156] Firstly, for controlling the duration of the resonance cycle and the initial switching instant to, the comparator 56 is intended to deliver a square-wave voltage with a high logic level if the voltage Vramp is greater than a predefined voltage V M and with a low logic level if the Vramp voltage is lower than the VM voltage. The VM voltage is also called the end of ramp voltage.

[0157] Secondly, for controlling the following switching times t1 to t5, the comparator 56 is intended, for each switching time f corresponding to its respective switch 14, to deliver a square-wave voltage with:

[0158] - a respective high logic level if the Vramp voltage is greater than:

[0159] + the control voltage Vu when the voltage Vu is between the minimum stop Vti_min and the maximum limit Vti_max;

[0160] + the minimum stop Vti min when the control voltage Vu is lower than the stop minimum Vti min; or

[0161] + the maximum stop Vti max when the control voltage Vu is greater than the stop maximum Vti max; and

[0162] - a low logic level otherwise.

[0163] Alternatively, the corrector 52 directly integrates a voltage limiter Vti_min, Vti_max, for example, in the case of an integrating corrector, by stopping integrating outside these voltage limits.

[0164] The control unit 58 is connected to the output of the comparator 56, and is then able to receive as input the square wave voltage, characterizing an opening or closing control signal, depending on the corresponding switching time.

[0165] The control unit 58 comprises for example a logic circuit, or an RS (Reset Set) type flip-flop, or a D type flip-flop, each configured to generate the control order for the switch in question from the opening or closing control signals, the rising edge of the closing control signal, denoted CompOn, indicating the closing time of the switch in question and the rising edge of the opening control signal, denoted CompOff, indicating the opening time of the switch in question.

[0166] The control unit 58 then comprises for example an RS flip-flop, with the S input connected to CompOn and the R input connected to CompOff, the Q output delivering the control signal of the switch in question; or a D flip-flop with Reset, with the D input in the high state, the Clock input connected to CompOn and the R input connected to CompOff, the Q output delivering the control signal of the switch in question; or a logic circuit performing the operation (CompOn and Not(CompOff)), the result forming the control signal of the switch in question.

[0167] The control unit 58 is connected to the input of the respective switch 14, and is configured to apply the opening control signal, or respectively the closing control signal, to a control electrode of the switch 14, such as a gate electrode when the switch 14 comprises a transistor such as a MOSFET or an IGBT.

[0168] As seen in [Fig.4], the ramp generator 54 comprises an amplifier operational 60, a source follower 62, a current mirror 64 and a generation unit 66.

[0169] The operational amplifier 60 is connected, by its positive input, to the output of the corrector 52, and is then able to receive the voltage VM.

[0170] The negative input of the operational amplifier is connected to the output of the source follower 62.

[0171] The source follower 62 comprises a transistor T1, a transistor T2 and a resistor Ro, the transistor T2 and the resistor Ro being connected in series and forming an equivalent resistance Rtot. The control electrode of the transistor T1 is connected to the output of the operational amplifier 60.

[0172] A first conduction electrode of the transistor Tl is connected to the negative terminal of the operational amplifier 60 and to the equivalent resistance Rtot, a second conduction electrode of the transistor Tl delivering a current Ip

[0173] The operational amplifier 60 is therefore intended to compensate the threshold voltage of the transistor T1, in order to reduce the variation of the current L.

[0174] By electrical configuration, the current L typically verifies the following equation:

[0175] [Math.l] i — 221

[0176] where Ii represents the current at the output of transistor Tl and at the input of current mirror 64,

[0177] VM represents the output voltage of the corrector 52,

[0178] Rtot represents the equivalent resistance formed by placing transistor T2 in series with resistor Ro.

[0179] The control of transistor T2 is for example connected to a high potential, such as a supply voltage VDD, to keep transistor T2 closed.

[0180] The current mirror 64 comprises two transistors T3 and T4, the transistors T3 and T4 being, for example, PMOS type transistors.

[0181] The current mirror 64 is connected to the output of the source follower 62, by its connection with the second conduction electrode of the transistor T1 and therefore receives the current L.

[0182] The current mirror 64 is intended to deliver at the output a current substantially identical to the current L, typically to within 5%, whatever the load applied at the output of the current mirror 64.

[0183] Current II is applied to the control electrodes of transistors T3 and T4 and to a first conduction electrode of T3, second conduction electrodes of transistors T3 and T4 being electrically connected to each other; and a replicated current IR being obtained at a first conduction electrode of T4.

[0184] The generation unit 66 comprises a branch circuit 67 as well as a pulsing module 68.

[0185] The generation unit 66 is connected to the output of the current mirror 64, and is then able to receive the IR current as input.

[0186] The branch circuit 67 is intended to deliver the voltage Vramp.

[0187] The branch circuit 67 comprises 6 electrical branches 70, 72, 74, 76, 78 and 80 in derivation, the voltage Vramp being at the terminals of each of the electrical branches 70, 72, 74, 76, 78 and 80. Of course, it is possible to use any other number of branch(es) including at least branch 80, the higher the number of branches, the finer the frequency adjustment can be and / or over a wide frequency range.

[0188] The first branch 70 comprises a capacitor C0.

[0189] The value of the capacitor C0 is typically between 0.1 and 10 pF, in particular substantially equal to 0.7 pF.

[0190] The second branch 72 comprises a switch PO, the switch PO being intended to be controlled by the pulsing module 68.

[0191] The third branch 74 comprises a capacitor Cl and a switch PI, the capacitor Cl and the switch PI being connected in series.

[0192] The value of the capacitor Cl is typically between 0.04 and 10 pF, in particular substantially equal to 0.4 pF.

[0193] The PI switch is intended to be controlled by a control bit bi predefined by the user, the PI switch being in the open position when the bit bi is equal to 0 and in the closed position when the bit bi is equal to 1.

[0194] The fourth branch 76 comprises a capacitor C2 and a switch P2, the capacitor C2 and the switch P2 being connected in series.

[0195] The value of capacitor C2 is typically between 0.4 and 50 pF, in particular substantially equal to 4 pF.

[0196] The switch P2 is intended to be controlled by a control bit b2 predefined by the user, the switch P2 being in the open position when the bit b2 is equal to 0 and in the closed position when the bit b2 is equal to 1.

[0197] The fifth branch 78 comprises a capacitor C3 and a switch P3, the capacitor C3 and the switch P3 being connected in series.

[0198] The value of capacitor C3 is typically between 1 and 150 pF, in particular substantially equal to 12 pF.

[0199] Switch P3 is intended to be controlled by a control bit b3 predefined by the user, switch P3 being in the open position when bit b3 is equal to 0 and in the closed position when bit b3 is equal to 1.

[0200] The sixth branch 80 comprises a switch P4, the switch P4 being intended to be controlled by the pulsation module 68.

[0201] The different possible configurations of the shunt circuit 67, due to its plurality of capacitors and switches, then make it possible to roughly adjust the value of the slope a of the triangular voltage Vramp. This adjustment of the slope a then makes it possible to define the periodicity of the switching times of all the switches 14.

[0202] As an example, this capacitive configuration is used to preset a central frequency. Regulation via the VM voltage, also called the end-of-ramp voltage, then makes it possible to adjust the frequency around this central frequency. This is a presetting either in advance or at the start of the converter 10 to place itself on a frequency band consistent with the piezoelectric resonator 15 on the chosen resonance mode.

[0203] For the adjustment, it is for example possible to proceed as follows:

[0204] - identify the useful frequency range of the piezoelectric resonator 15;

[0205] - determine the central frequency of this range;

[0206] - identify the central value of the voltage VM;

[0207] - calculate the Cramp value according to the following equation:

[0208] [Math.2] _ vw ^ramp~ fw

[0209] where Cramp denotes a total value of the capacity of branches 70, 72, 74, 76, 78 and 80,

[0210] VM represents the output voltage of the corrector 52, in particular the central value aforementioned,

[0211] framp denotes the frequency of the reference triangular signal 45, in particular the aforementioned central frequency,

[0212] AVramp = Vramp max - Vramp min, where Vramp max denotes the maximum value of the voltage ramp Vramp, and Vramp min denotes the minimum value of said ramp, the values ​​Vramp_ max and Vramp n]in being predefined and controlled by the user, and

[0213] Rtot represents the equivalent resistance formed by placing transistor T2 in series with resistor Ro;

[0214] - apply the configuration of PI, P2 and P3 which allows to obtain the capacitive value closest to the desired Cramp value.

[0215] The pulsation module 68 is connected to the output of the comparator 56 associated with the regulation of the duration of the resonance cycle, i.e. the regulation of the resonance period, and is then capable of receiving a voltage Vreset as input.

[0216] The voltage Vreset is a square wave voltage, presenting a high logic level if the voltage Vramp exceeds the end of ramp voltage VM, and a low logic level otherwise.

[0217] The pulsing module 68 is intended to discharge the capacitors C0, Cl, C2 and C3 when the voltage Vreset has a high logic level, indicating that the ramp has enabled the switching of all switching instants and that it must therefore be reset. to initialize.

[0218] The pulsation module 68 is intended to control the switches PO and / or P4 in their closed position, in order to discharge the capacitors CO, Cl, C2 and C3; when the threshold voltage VM allowing the control of the last switching instant is desired.

[0219] The pulsation module 68 is capable of delivering a voltage Vpuise whose time width is predefined and makes it possible to choose a discharge duration D of the capacitors CO, Cl, C2 and C3.

[0220] The discharge duration D of the capacitors is typically less than 10 ns, for example chosen between 2 ns, 5 ns and 10 ns.

[0221] The switch PO is directly controlled by the voltage Vpuise.

[0222] Switch P4 is controlled via an AND logic gate 82.

[0223] The AND logic gate 82 is connected to the output of the pulse module 68 and an OR logic gate 84, and then able to receive as input the voltage Vpuise and a voltage V GOLD*

[0224] The AND logic gate 82 is capable of delivering a voltage Vand as output, the voltage Vand typically also being in the form of a square wave voltage with a high logic level if the voltages Vpuise and VOr have a high logic level, and with a low logic level otherwise. The switch P4 is controlled in the closed position if Vand has a high logic level, or is controlled in the open position if Vand has a low logic level.

[0225] The logic gate OR 84 is capable of receiving as input the bit b2 and the bit b3, previously defined by the user.

[0226] The OR logic gate 84 is capable of delivering the voltage V0R ​​as output, the voltage V0R ​​typically being in the form of a square wave voltage with a high logic level if b2 and / or b3 has a value equal to 1, and with a low logic level otherwise.

[0227] For example, switch P4 is arranged closest to capacitors C2 and C3, because capacitors C2 and C3 have typically larger capacitances than capacitors C0 and C1 and require more time to discharge. Switch P4 is therefore only controlled when capacitor C3 or C4 or both are used for generating the ramp signal.

[0228] The framp frequency typically verifies the following equation:

[0229] [Math.3] y _Ew IClmp C'ramp&VrampRfvf

[0230] where the parameters are identical to those of the previous equation [Math 2].

[0231] The Cramp capacitance typically satisfies the following equation:

[0232] [Math.4] Cramp — CO + Zq.Cl + £>2-C2 + &3.C3

[0233] where Cramp denotes the total value of the capacitance of branches 70, 72, 74, 76, 78 and 80, possibly supplemented by parasitic capacitances, for example the parasitic capacitances of switches PO to P4,

[0234] C0, Cl, C2 and C3 respectively denote the capacities of the capacitors C0, Cl, C2 and C3,

[0235] bb b2 and b3 respectively designate the values ​​of the control bits of the switches PI, P2 and P3 (0 for a deactivated capacitor and 1 for an activated capacitor).

[0236] In the example described, Vramp_min = 0, which means that AVramp = Vrampmax, and also Vramp_max = VM, or here AVramp = Vramp_max = VM.

[0237] The nominal operation of a cycle of the converter 10 comprising a piezoelectric resonator 15 will now be described with regard to [Fig.6] showing the successive phases of a resonance cycle of the piezoelectric resonator, according to a generic format corresponding to different operating modes of the converter 10, namely a first operating mode M1, also called voltage boost mode; and a second operating mode M2, also called voltage step-down mode.

[0238] [Fig.6] then represents the evolution of the current [3*IL of the normalized current IL in amplitude circulating in the piezoelectric resonator 15 visible in [Fig.l]; of the voltage Vp at the terminals of the piezoelectric resonator 15; and of the mechanical deformation of the piezoelectric resonator 15, represented by the curve DM; this during a resonance cycle and for two operating modes of the converter 10, namely the first operating mode Ml in voltage booster, and the second operating mode M2 ​​in voltage step-down. With [3=-1 in voltage step-up operating mode Ml; and [3=+l in voltage step-down operating mode M2.

[0239] By convention, we define a first switching time instant, noted L.

[0240] At the time instant t0, a first phase I begins at substantially constant voltage, at the zero value according to the first mode M1 via the closing of the second switch K2, or at the input voltage Vin according to the second mode M2 ​​via the closing of the first switch K1, and lasts until a time instant ti which forms an adjustment parameter of the converter 10, this time instant ti making it possible to define the voltage, the current or even the desired power at the output of the converter 10.

[0241] The time instant ticorresponds then to the end of the first phase I and to the instant at which the second switch K2 according to the first mode M1, or respectively the first switch K1 according to the second mode M2, must then be open, the time instant ti forming a second switching time instant corresponding to the opening of the second switch K2 according to the first mode M1, or respectively of the first switch K1 according to the second mode M2.

[0242] At the second switching time instant ti, a second phase II begins, corresponding to a phase with a substantially constant load, or else in a substantially open circuit, this second phase II lasting until a time instant t2 defined by the transition to a new predefined value of the voltage Vp at the terminals of the piezoelectric resonator 15. When the converter 10 comprises three switches K1, K2, K3 capable of being controlled to alternate phases with a substantially constant voltage and phases with a substantially constant load at the terminals of the piezoelectric resonator 15, the time instant t2 forming the end of the second phase II typically corresponds to the closing of the third switch K3 according to the first mode M1, or respectively of the second switch K2 according to the second mode M2, the time instant t2 then forming a third switching time instant.

[0243] At time instant t2 then begins a third phase III corresponding to a phase at substantially constant voltage at output voltage Vout according to the first mode M1 via the closing of the third switch K3, or at zero value according to the second mode M2 ​​via the closing of the second switch K2. This third phase III lasts until time instant t3.

[0244] From the zero crossing of the current IL flowing in the piezoelectric resonator 15, a fourth phase IV then begins, corresponding to a phase with substantially constant charge, this fourth phase flowing between the time instant t3 and the time instant t4. The end of this fourth phase VI corresponds to the moment when the voltage Vp at the terminals of the piezoelectric resonator 15 reaches the input voltage Vin according to the first mode M1, or the output voltage Vout according to the second mode M2.

[0245] A fifth switching time instant, denoted t4, corresponds to the closing of the first switch K1 for the first mode M1, respectively of the third switch K3 for the second mode M2, and the voltage Vp across the terminals of the piezoelectric resonator 15 is then substantially constant and equal to the input voltage Vin according to the first mode M1, or to the output voltage Vout according to the second mode M2. At this fifth switching time instant t4 then begins a fifth phase V lasting until the opening of the switch which was closed at the fifth switching time instant t4.

[0246] A sixth switching time instant, denoted t5, corresponds to the opening of the first switch Kl for the first mode Ml, respectively of the third switch K3 for the second mode M2, and the voltage Vp at the terminals of the piezoelectric resonator 15 then changes from a previous voltage Vin according to the first mode Ml, or Vout according to the second mode M2, to an open circuit position. At this sixth switching time instant t5 then begins a sixth phase VI during up to a time instant t6 corresponding to a zero crossing of the current IL flowing in the piezoelectric resonator 15. Previously, the time instant t5 was defined so that at the time instant t6, the voltage Vp at the terminals of the piezoelectric resonator 15 reaches a value corresponding to the value allowing a zero voltage switching of the corresponding switch.

[0247] By convention, the time instant t6 is equal to the sum of the time instant t0 and the period T of the resonance cycle, and is also noted (t0+T).

[0248] In the example of [Fig.6], the time instant t6 corresponds to the end of a resonance cycle of the piezoelectric resonator 15.

[0249] The method for controlling an electrical energy converter 10 via the control device 20 will now be described with reference to the flowchart of [Fig.5], the method comprising three distinct steps.

[0250] During a first step 100, the measurement module 40 measures the regulation quantity Greg of the converter 10. The regulation quantity Greg is advantageously the voltage Vp across the terminals of the resonator 12.

[0251] During a second step 110, the generation module 42 generates the reference triangular signal 45, then synchronizes it with the regulation quantity Greg measured by the measurement module 40, the regulation quantity Greg depending on the oscillation frequency of the resonator 12.

[0252] Advantageously, the generation module 42 synchronizes the reference triangular signal 45 with the regulation quantity Greg at least once per resonance cycle, in particular once per resonance cycle.

[0253] During a third step 120, the control module 44 receives the reference triangular signal 45 from the generation module 42, in particular via the ramp generator 54, and controls a switching of each of the switches 14, according to several successive phases during a resonance cycle of the resonator 12, each phase resulting from a switching of at least one respective switch.

[0254] The switching times of the different switches 14 are determined by comparison with the reference triangular signal 45.

[0255] In the example described, each switching instant t0, tb t2, t3, t4, t5 or L is connected to a respective control signal, here a respective control voltage Vt0, Vti, Vt2, Vt3, Vt4, Vt5 or Vt6. The switch associated with each instant L, tb t2, t3, t4, t5 or t6 is then switched when the voltage Vramp corresponding to the reference signal reaches the respective control voltage Vt0, Vtb Vt2, Vt3, Vt4, Vt5, Vt6, or the respective minimum stop Vt0_min? Vtl_min» Vt2_min? Vl3_lnm, Vt4_min, Vt5_min, Vt6_minlorSqUe the respective control voltage Vti is lower than said respective minimum stop Vti_min; or the respective maximum limit Vt0_max, Vü_max, Vt2_max, Vt3_max, Vt4_max, Vt5_max, Vt6_max when the respective control voltage Vti is greater than said maximum limit Respective Vti_max; as schematically visible in [Fig.7].

[0256] It is thus understood that the electronic control device 20 and the control method according to the invention allow precise control of the control times of the switches 14, and this in a manner synchronized with the regulation quantity Greg which is representative of the resonator 12.

[0257] The high precision of the switching instants, obtained thanks to the invention, then makes it possible to minimize switching losses and to maintain smooth switching conditions, in particular at zero voltage or ZVS (from the English Zero Voltage Switching), which allows the converter 10 to operate optimally at high frequencies.

Claims

Claims

1. Electronic control device (20) for an electrical energy converter (10) capable of converting an input voltage (Vin) into an output voltage (Vout), the converter (10) comprising two input terminals for receiving the input voltage (Vin), two output terminals for delivering the output voltage (Vout), a resonator (12), and several switches (14) connected to the resonator (12), the resonator (12) resonating according to successive resonance cycles, each resonance cycle having a duration equal to a resonance period, the resonance period being equal to the inverse of an oscillation frequency of the resonator (12); the electronic control device (20) comprising: - a measurement module (40) configured to measure a regulation quantity (Greg), the regulation quantity being a quantity representative of the resonator (12);- a control module (44) configured to control, via a control unit (58), a switching of each of the switches (14), following several successive phases during a resonance cycle of the resonator (12), each phase resulting from the closing of at least one respective switch (14) and the opening of the other switches (14); characterized in that it further comprises: - a generation module (42) configured to generate a reference triangular signal (45), regularly synchronized with the regulation quantity (Greg), a characteristic quantity (Gcar) of the reference triangular signal (45) depending on the oscillation frequency of the resonator (12); the control module (44) being configured to control at least one of the switches (14) from a comparison with the reference signal.;

2. Device according to claim 1, in which the generation module (42) is configured to synchronize the reference signal with the regulation quantity (Greg) at least once per resonance cycle.

3. Device according to claim 1 or 2, in which the regulation quantity (Greg) is a voltage across the terminals of the resonator (12); the reference signal preferably being a triangular voltage (Vramp)•

4. Device according to any one of the preceding claims, in which the reference triangular signal (45) is periodic and in the form of a ramp at each period; the ramp having a period, called the ramp period (Tramp), the ramp period (Tramp) preferably being equal to the resonance period, the ramp period (Tramp) then being equal to the inverse of the oscillation frequency of the resonator.

5. Device according to claim 4, in which a period start time instant of the reference signal is determined as a function of the control quantity (Greg); the period start time instant preferably depending on a time instant at which the time derivative of the control quantity (Greg) is zero.

6. Device according to claim 5, in which the period start time instant is anticipated with respect to a switching time instant (h) of a corresponding switch, a time difference between the period start time instant and the switching time instant (h) depending on a processing delay by the control unit (58), from the emission of a switching command until the switching of the switch (14).

7. Device according to any one of the preceding claims, in which the characteristic quantity (Gcar) is chosen from the group consisting of: a slope (a) of the reference triangular signal (45) and an amplitude (Amp) of the reference triangular signal (45).

8. Device according to any one of claims 4 to 6, taken with claim 7, wherein when the characteristic quantity (Gcar) is the slope (a) of the reference triangular signal (45), the slope (a) of the ramp is proportional to the oscillation frequency of the resonator; the ramp preferably having a fixed amplitude (Amp); the slope (a) of the ramp preferably varying further as a function of the oscillation frequency of the resonator (12) when the amplitude (Amp) of the ramp is fixed; wherein when the characteristic quantity (Gcar) is the amplitude (Amp) of the reference triangular signal (45), the amplitude (Amp) is inversely proportional to the oscillation frequency of the resonator (12); the ramp preferably having a fixed slope (a); the amplitude (Amp) of the ramp preferably varying further as a function of the oscillation frequency of the resonator (12) when the slope (a) is fixed.

9. Device according to any one of the preceding claims, in which the control module (44) is configured to control several switches (14) one after the other, corresponding to several phases of the resonance cycle, each control being carried out from a respective comparison with the reference signal.

10. Device according to any one of the preceding claims, wherein the control module (44) is configured to control each switch (14) at a respective control instant, obtained by comparing a control signal with the reference signal, and each switch is associated with at least one respective control signal; a minimum stop and a maximum stop being predefined for each control signal, the minimum and maximum stops defining minimum and maximum values ​​of the control instant; the control signal and the reference signal being preferably still voltages (Vti), and the minimum and maximum stops then being minimum (Vti_min) and maximum (Vti_max) voltages.

11. Device according to any one of the preceding claims, wherein the switches (14) comprise: - a first switch (Kl) connected between one of the input terminals and the resonator (12), the first switch (Kl) being switchable between an open position and a closed position in which the input voltage (Vin) is applied to the terminals of the resonator (12); - a second switch (K2) connected to the terminals of the resonator (12), the second switch (K2) being switchable between an open position and a closed position in which the voltage is zero across the terminals of the resonator (12); and - a third switch (K3) connected between one of the output terminals and the resonator (12), the third switch (K3) being switchable between an open position and a closed position in which energy from the resonator (12) is restored to the output voltage (Vout).

12. A device according to any one of claims 1 to 11, wherein the resonator (12) is a piezoelectric resonator (15); the piezoelectric resonator (15) preferably being constituted according to one of the constitutions among the group consisting of: a single piezoelectric element; several piezoelectric elements connected in series; several piezoelectric elements connected in parallel; a piezoelectric element and an auxiliary capacitor connected in series; a piezoelectric element and an auxiliary capacitor connected in parallel; and an arrangement of several parallel branches, each branch comprising one or more piezoelectric elements connected in series or an auxiliary capacitor; the auxiliary capacitor being more preferably of a capacitance greater, more preferably at least three times greater, than a reference capacitance of the piezoelectric element(s), each piezoelectric element being modeled as a capacitor and a resonant branch connected in parallel to the capacitor, the reference capacitance being the capacitance of said capacitor.

13. Device according to the preceding claim, in which the control module (44) is configured to control the switching of each of the switches (14) to alternate phases at substantially constant voltage across the terminals of the piezoelectric resonator (15) and phases at substantially constant charge across the terminals of said piezoelectric resonator (15).

14. A device according to any one of claims 1 to 11, wherein the resonator (12) is an LC resonator comprising an inductor and a capacitor connected in series with the inductor.

15. An electrical energy conversion system (5) comprising: - an electrical energy converter (10) capable of converting an input voltage (Vin) into an output voltage (Vout), the converter (10) comprising two input terminals for receiving the input voltage (Vin), two output terminals for delivering the output voltage (Vout), a resonator (12), and several switches (14) connected to the resonator (12), the resonator (12) resonating according to successive resonance cycles, each resonance cycle having a duration equal to a resonance period, the resonance period being equal to the inverse of an oscillation frequency of the resonator; and - an electronic control device (20) for controlling the electrical energy converter (10); characterized in that the control device (20) is according to any one of the preceding claims.

16. Method for controlling an electrical energy converter (10) capable of converting an input voltage (Vin) into an output voltage (Vout), the converter (10) comprising two input terminals for receiving the input voltage (Vin), two output terminals for delivering the input voltage (Vout), and two output terminals for delivering the output voltage (Vout). output (Vout), a resonator (12), and several switches (14) connected to the resonator (12), the resonator (12) resonating following successive resonance cycles, each resonance cycle having a duration equal to a resonance period, the resonance period being equal to the inverse of an oscillation frequency of the resonator; the method being implemented by an electronic control device (20) and comprising the following steps: - measurement (100) of a regulation quantity (Greg), the regulation quantity (Greg) being a quantity representative of the resonator (12); - control (120), via a control unit (58), of a switching of each of the switches (14), following several successive phases during a resonance cycle of the resonator (12), each phase resulting from the closing of at least one respective switch (14) and the opening of the other switches (14), characterized in that it further comprises: - generation (110) of a reference triangular signal (45), regularly synchronized with the regulation quantity (Greg), a characteristic quantity (Gcar) of the reference triangular signal (45) depending on the oscillation frequency of the resonator (12); the control (120) of at least one of the switches (14) being carried out from a comparison with the reference signal.

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