Electronic device and method for controlling an electrical energy converter, associated electronic conversion system and computer program

Abstract

Electronic device and method for controlling an electrical power converter, associated electronic conversion system and computer program. This electronic control device controls a power converter that delivers a total output voltage and / or output current from a plurality of elementary DC input voltages, each originating from a respective power source. The converter comprises several conversion modules, each receiving an elementary DC input voltage from a respective source and delivering an elementary output voltage; the conversion modules are connected in series via their outputs, and the total output voltage is equal to the sum of the elementary output voltages; each conversion module includes several switches for converting the respective elementary DC input voltage into the respective elementary output voltage.The control system comprises several elementary controllers and a master controller connected to them. Each elementary controller is associated with a respective conversion module and controls the switches of that module. The master controller regulates the converter's output by sending control commands to the elementary controllers. This regulation is based on sets of elementary variables, each associated with a respective conversion module. Each elementary controller regularly measures values ​​of these sets of variables for its associated conversion module and then transmits them to the master controller. These values ​​include the elementary DC input voltage.The main controller includes a first estimator that calculates, for each conversion module, an estimated value of the elementary DC input voltage from a previously measured value of the elementary DC input voltage. Figure for the abstract: None.

Description

Title of the invention: Electronic device and method for controlling an electrical energy converter, associated electronic conversion system and computer program

[0001] The present invention relates to an electronic control device for an electrical energy converter.

[0002] The power converter is capable of delivering a total output voltage or a current at an output voltage from a plurality of DC input voltages, each originating from a respective power source. The power converter comprises several power conversion modules, each capable of receiving at its input an elementary DC input voltage from a respective power source and delivering at its output an elementary output voltage. The conversion modules are connected in series via their outputs, and the total output voltage is equal to the sum of the elementary output voltages. Each conversion module includes several switches for converting the respective elementary DC input voltage into the respective elementary output voltage.

[0003] The electronic control device comprises several elementary controllers, also called local controllers, and a main controller, also called central controller or master controller, connected to each of the elementary controllers, each elementary controller being associated with a respective conversion module and configured to control the switches of said conversion module.

[0004] The main controller is configured to regulate an output quantity of the power converter by sending control commands to the elementary controllers, the regulation being carried out according to sets of elementary quantity(ies), each set of elementary quantity(ies) being associated with a respective conversion module.

[0005] Each elementary controller is configured to regularly measure values ​​of the set of elementary quantity(ies) for the respective conversion module to which it is associated, and then to transmit them to the main controller, the set of elementary quantity(ies) comprising the elementary DC input voltage.

[0006] The invention also relates to an electronic electrical energy conversion system capable of converting a plurality of DC input voltages into a total output voltage, the conversion system comprising such an energy converter and such an electronic device for controlling the electrical energy converter.

[0007] The invention also relates to a method of controlling such an electrical energy converter; as well as a computer program comprising software instructions which, when executed by a computer, implement such a control method.

[0008] Such an electrical energy converter is generally called a multilevel converter, and many articles present solutions for driving such multilevel converters.

[0009] Among these, the article "A Decentralized Control Method for Serial Connected PV Battery Hybrid Microgrid" by Y. Pan et al. (2017) concerns the energy management of a multi-level, multi-source inverter connected to the grid. Two types of sources are used: solar panels and batteries. The objective of the article is to present a method for managing the energy production of the panels and the charging / discharging of the batteries. Each level consists of an energy source (solar panel or battery) and a DC-AC conversion module, commonly denoted DC / AC (Direct Current / Alternating Current). The DC / AC conversion module includes a decoupling capacitor at the source, an H-bridge enabling the production of an alternating voltage from a DC source, and an output filter. The H-bridge is controlled by a basic controller, called the local controller.Each local controller receives active and reactive power production instructions from a single main controller, called the central controller. Meanwhile, the individual controllers send data related to the energy source (battery charge level, solar panel voltages). This data is sent via a low-bandwidth communication bus. The main controller then regulates each solar panel around its maximum power point, controls the battery charge level, and produces a regulated sinusoidal current on the electrical grid.

[0010] However, such a control system is costly and complex. Indeed, each elementary controller requires four measurements from four sensors, three of which measure alternating differential data (two currents and one voltage). Furthermore, the switching of the energy conversion modules is not coordinated with each other (the local controller receives only a setpoint and not a switching command; it performs numerous switching operations to follow its setpoint independently of the other modules), thus preventing the reduction of a shared filter on the overall output, and requiring an efficient output filter at the level of each module (more expensive and bulky, and a high cumulative number of switching operations across all modules, increasing overall losses).

[0011] The energy converter and the control device presented in the article "Hybrid Microgrid With Parallel- and Series-Connected Microconverters" by J. He and al (2018) continue the work of Y. Pan et al (described in the aforementioned article) within the same laboratory (Tianjin University, Tianjin, China). This article focuses on the parallelization of multilevel inverters to improve redundancy in power generation.

[0012] However, again, the elementary controllers are complex circuits (high-performance microcontroller, as well as many expensive sensors) which limit their use, especially if the number of conversion modules is high, typically more than 5. Similarly, the switching is not coordinated: more switching leads to more losses and a accumulation of large and expensive output filters compared to globally coordinated switching.

[0013] The article "A Grid-Supporting Strategy for Cascaded H-Bridge PV Converter Using VSG Algorithm With Modular Active Power Reserve" by X. Zhang et al. (2021) also concerns the control of a multilevel inverter, in this case a solar inverter without batteries. The article highlights the relevance of this converter for playing a supporting role for the electrical grid through VSG (Virtual Synchronous Generator) operation.

[0014] However, the converter described in this article comprises only five conversion modules, and has a low operating frequency of 2.5 kHz.

[0015] The aim of the invention is then to propose a control device for such a multi-level energy converter allowing high-frequency control, typically above 20kHz, of said converter which can also be connected to a large number of energy sources, for example to more than ten energy sources, while reducing the complexity of the control device, as well as the size and volume of the output filtering elements.

[0016] To this end, the invention relates to an electronic control device of the aforementioned type, in which the main controller includes a first estimator configured to calculate, for each conversion module, an estimated value of the elementary DC input voltage from a previously measured value of the elementary DC input voltage.

[0017] With the electronic control device according to the invention, the first estimator makes it possible to operate the power converter at a switching frequency fsw higher than the refresh rate fD of a data link, such as a data bus, connecting the main controller to the elementary controllers, without reducing the stability and accuracy of the regulation of each elementary DC input voltage. It should be noted that the higher the switching frequency fsw, the more compact the output filter. In the context of the invention, the switching of the modules is coordinated at the level of the main controller, which switches only a minimal number of modules at the switching frequency fsw. On the contrary, the prior art described above switches all modules at high frequencies, leading to losses without limiting the output current ripple, since the switching of each elementary output is managed in an uncoordinated manner. While, for a given current or voltage ripple, the elementary output filter is smaller as the frequency increases, for the same current or voltage ripple and the same switching frequency, it is in all cases larger than in the context of the invention, where the switching is coordinated.

[0018] A critical point to be solved by the invention is the ability, at the level of the main controller, to determine each switching operation of each module (and not just calculate a setpoint) while having access to data measured on the modules at a refresh rate fD lower than the switching frequency fsw. This allows for coordinated switching without requiring very high-speed measurement and communication means.

[0019] Advantageously, as an optional complement, the second estimator also allows this operation of the energy converter at the switching frequency fsw higher than the refresh frequency fD, while maintaining stability and accuracy in the regulation of each elementary input current, and then of the resulting total output current.

[0020] In addition, the first estimator, and advantageously the second estimator, make it possible to limit the number of sensors required at the level of the conversion modules or the elementary controllers, since the control device only requires voltage sensors capable of measuring the elementary DC input voltages, typically one voltage sensor per conversion module.

[0021] According to other advantageous aspects of the invention, the electronic control device comprises one or more of the following features, taken individually or in all technically possible combinations:

[0022] - each conversion module comprises two input terminals, two output terminals output, a switching bridge with several switching branches, each connected between the two input terminals and comprising several switches connected in series and linked together with a midpoint connected to a corresponding output terminal, each conversion module further comprising a capacitor connected between the input terminals, in parallel with the switching bridge;

[0023] - the first estimator is configured to calculate, for each module of conversion, the estimated value of the elementary DC input voltage as a function of the previously measured value of the elementary DC input voltage, the capacitance of the capacitor and a value of the current flowing through said capacitor;

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[0038] the value of the current flowing through said capacitor being preferably obtained by the difference between a value of an elementary input current received by the conversion module and a value of a bridge current received by the switching bridge; - The first estimator is configured to calculate, for each conversion module, the estimated value of the elementary DC input voltage according to the following equation: Vpv^h) - Vpv^tk-l) + (^pv^h) )-c“ where (tk) represents the estimated value of the elementary DC input voltage, Vpvi(tk-i) represents a previous value of the elementary DC input voltage, Ipvi(tk) represents the value of the elementary input current, tk, and respectively tk [, represent respectively current and previous time instants, Cpvi represents the capacitance of the capacitor. IHi_M (tk) represents the average value of the bridge current between the time instants tk i and tk; the previous value VPVi (tk-i) of the elementary DC input voltage being the previously measured value of the elementary DC input voltage if it was measured for the previous time instant, or the previous estimated value of the elementary DC input voltage if said previously measured value was measured for a time instant prior to the previous time instant; said average value IHi_M(tk) of the bridge current preferably satisfying the following equation: - the main controller also includes a second estimator configured to calculate, for each conversion module, an estimated average of the elementary input current received by the conversion module, the estimated average of the elementary input current then being used to calculate the estimated value of the elementary DC input voltage; - the second estimator is configured to calculate, for each conversion module, the estimated average of the elementary input current over an averaging period, as a function of the total output voltage and output current delivered at the output of the power converter, and an average value of the elementary DC input voltage over the averaging period; the average duration depending preferably on half a period of the voltage exit;

[0039] - the second estimator is configured to calculate, for each module of conversion, the estimated average of the elementary input current according to the following equation: 100401 ,, s <hv,> -----

[0041] where <ipvi>represents the estimated average of the elementary input current,

[0042] Tg represents the average duration,

[0043] Vs represents the total output voltage,

[0044] Is represents the output current,

[0045] <vpvi>represents the average value of the elementary DC input voltage over said averaging period, and

[0046] K; represents a connection coefficient, K; being equal to 0 when no energy source is connected to the input of the corresponding conversion module and different from 0 when at least one energy source is connected to the input of said module;

[0047] the average duration being preferably a multiple of the half-period of the output voltage, said multiple being an integer with a value greater than or equal to 1;

[0048] - the main controller further includes a third estimator configured for calculate, for each conversion module, an estimated value of the capacitor's capacitance;

[0049] - the third estimator is configured to estimate a current value of the capacity of the capacitor by correcting a previous estimated value of the capacitor's capacitance based on, on the one hand, the sign of the difference between a value of a bridge current received by the switching bridge and a value of an elementary input current received by the conversion module, called the first sign, and on the other hand, the sign of the difference between the estimated value of the elementary DC input voltage and the subsequently measured value of the elementary DC input voltage, called the second sign; an initial estimated value of the capacitor's capacitance being predefined;

[0050] if the first and second signs are identical, the current estimated value of the capacitor capacitance is preferably equal to the previous estimated value of the capacitor capacitance less one correction step;

[0051] if the first and second signs are distinct, the current estimated value of the capacitor capacitance is preferably equal to the previous estimated value of the capacitor capacitance increased by the correction step;

[0052] the correction step preferably being on the order of a percent of the initial value of the capacitance of the capacitor;

[0053] - each energy source comprises at least one element chosen from: a pho block tovoltaic, an electric battery and a supercapacitor;

[0054] - each energy source comprises P pair(s) of photovoltaic blocks, the blocks photovoltaic cells of a respective pair being connected in cascade, P being an integer greater than or equal to 1;

[0055] if P is strictly greater than 1, the pairs of photovoltaic blocks being preferably connected in cascade.

[0056] - each conversion module comprises Q capacitors, where Q, equal to twice the The number P represents the number of photovoltaic blocks for the energy source associated with the conversion module, each capacitor being suitable for connection in parallel with a respective photovoltaic block, the Q capacitors having a substantially identical capacitance, and

[0057] wherein when the connection coefficient is non-zero, its value is a multiple of 1 / Q, the multiple being a relative integer whose value depends on a connection configuration of the photovoltaic blocks and a connection state of each of the photovoltaic blocks, each connection state being among connected and disconnected.

[0058] The invention also relates to an electronic system for converting electrical energy capable of converting a plurality of DC input voltages into a total output voltage and / or output current, the conversion system comprising:

[0059] - a power converter capable of delivering the total output voltage and / or the current output from a plurality of DC input voltages, each originating from a respective power source; the power converter comprising several power conversion modules, each capable of receiving at its input an elementary DC input voltage from a respective power source and delivering at its output an elementary output voltage; the conversion modules being connected in series by their outputs and the total output voltage being equal to the sum of the elementary output voltages; each conversion module having several switches for converting the respective elementary DC input voltage into the respective elementary output voltage,

[0060] - an electronic control device for the electrical energy converter, the electronic control device being as defined above.

[0061] The invention also relates to a method for controlling an electrical energy converter,

[0062] the power converter being capable of delivering a total output voltage and / or an output current from a plurality of DC input voltages, referred to as elementary DC input voltages, each originating from a respective energy source; the power converter comprising several conversion modules of energy, each being capable of receiving at its input an elementary DC input voltage from a respective energy source and of delivering at its output an elementary output voltage; the conversion modules being connected in series by their outputs and the total output voltage being equal to the sum of the elementary output voltages; each conversion module having several switches to convert the respective elementary DC input voltage into the respective elementary output voltage,

[0063] the control method being implemented by a main controller connected to each of several elementary controllers, each elementary controller being associated with a respective conversion module and configured to control the switches of said conversion module, the method comprising:

[0064] - to regulate an output quantity of the energy converter by sending control commands to the elementary controllers, regulation being carried out according to sets of elementary quantity(ies), each set of elementary quantity(ies) being associated with a respective conversion module, each elementary controller regularly measuring values ​​of the set of elementary quantity(ies) for the respective conversion module to which it is associated, then transmitting them to the main controller, the set of elementary quantity(ies) including the elementary DC input voltage,

[0065] - calculate, for each conversion module, an estimated value of the voltage elementary DC input from a previously measured value of the elementary DC input voltage.

[0066] The invention also relates to a computer program comprising software instructions which, when executed by a computer, implement a control method as defined above.

[0067] These features and advantages of the invention will become clearer upon reading the following description, given solely by way of non-limiting example, and made with reference to the accompanying drawings, in which:

[0068] [Fig-1] [Fig.1] is a schematic representation of an electronic system of electrical energy conversion according to the invention, the conversion system comprising an energy converter capable of delivering a total output voltage from a plurality of DC input voltages and an electronic control device for the electrical energy converter, each DC input voltage being derived from a respective energy source; the converter comprising several energy conversion modules, each capable of receiving at its input an elementary DC input voltage from a respective energy source and delivering at its output an elementary output voltage, each conversion module comprising several switches for converting the elementary DC input voltage respective in the respective elementary output voltage; the electronic control device comprising several elementary controllers and a master controller connected to each of the elementary controllers, each elementary controller being associated with a respective conversion module and configured to control the switches of said conversion module;

[0069] [Fig.2] [Fig.2] is a simplified electrical diagram of the included power converter in the conversion system of [Fig.1], the conversion modules are connected in series by their outputs and the total output voltage is equal to the sum of the elementary output voltages;

[0070] [Fig.3] [Fig.3] is a simplified electrical diagram representing other examples, than those represented in [Fig.2], of energy sources based on photovoltaic blocks and associated conversion modules;

[0071] [Fig.4] [Fig.4] is a more detailed schematic representation of each of the elementary controllers, of a control unit included in the main controller, as well as the parameters and quantities exchanged between the main controller and the elementary controllers;

[0072] [Fig. 5] [Fig. 5] is a flowchart of a converter control method electrical energy from [Fig.1], implemented by the main controller;

[0073] [Fig.6] [Fig.6] is a view with three curves associated with a DC voltage respective input values, representing respectively an actual value of said voltage; an estimated value of said voltage, calculated by a first estimator included in the main controller; and a measured value of said voltage, transmitted to the main controller by the respective elementary controller;

[0074] [Fig.7] [Fig.7] is a view with two curves associated with an elementary current input received by a respective conversion module, representing respectively a real value of said current, and an estimated value of said current, calculated by a second estimator included in the main controller;

[0075] [Fig.8] [Fig.8] is a view with two sets of curves, associated with a voltage elementary continuous input respective; a first set comprising two curves representing respectively an actual value of said voltage and an estimated value of said voltage, calculated by the first estimator; a second set comprising two curves representing respectively the actual value of said voltage and an estimated value of said voltage calculated by the first estimator for which a value of the capacitance of a capacitor connected at the input of the conversion module is further estimated by a third estimator included in the main controller;

[0076] [Fig.9] [Fig.9] is a schematic view illustrating the execution of a command to connection of a respective conversion module, received from the controller main ;

[0077] [Fig. 10] [Fig. 10] is a schematic view illustrating the execution of a connection order of a respective conversion module, received from the main controller;

[0078] [Fig. 11] [Fig. 11] is a schematic view illustrating the execution of a connection command of a respective conversion module, in the particular case where the frequency at which the calculations of the control unit included in the main controller are performed is substantially equal to a switching frequency of the switches of said conversion module; and

[0079] [Fig. 12] The [Fig. 12] is a view with three curves associated with the output of the power converter, representing respectively the voltage of an electrical network to which the output of the converter is connected, the total output voltage delivered by the converter, and the current of the electrical network.

[0080] In the present description, the expression "in the order of", as well as the expression "approximately equal to", are understood as a relationship of equality to plus or minus 20%, preferably to plus or minus 10%, preferably to plus or minus 5%.

[0081] In [Fig.1], an electronic electrical energy conversion system 5, hereafter referred to as the conversion system, is connected to an electrical network 6, in particular to supply it with electrical energy from energy sources 8.

[0082] The conversion system 5 is capable of converting a plurality of DC input voltages VPVi, VPV2, • VPVn, also called elementary DC voltages input VPVi, VPV2, • VPVn, each originating from a respective energy source 8, into a total output voltage Vs, typically delivered to the electrical network 6 possibly via a filter 16.

[0083] The conversion system 5 includes an energy converter 10 capable of delivering the total output voltage Vs from the plurality of DC input voltages VPVi, VPV2, • • - , VPVn and an electronic device 15 for controlling the electrical energy converter 10.

[0084] As an optional addition, the conversion system 5 includes a filter 16. The output voltage of the filter 16 supplies an output load, not shown, or is directly connected to the electrical network 6, or recharges a battery, not shown. In the example of [Fig. 2], the filter 16 is directly connected to the electrical network 6, and is thus connected between the power converter 10 and the electrical network 6. Alternatively, the output filter 16 is wholly or partly distributed along the power path, for example at each of the power conversion modules 35, described later and included in the power converter 10.

[0085] In the example in [Fig.2], filter 16 is an L-type filter, and comprises a The electromagnetic coil 18, also called the filter inductor, has an inductance LG. The voltage across the filter 16, and more specifically across the filter inductor 18, is denoted VL.

[0086] Alternatively, not shown, filter 16 is an LC type filter, and thus comprises an electromagnetic coil, or filter inductor, coupled to a filter capacitor. Alternatively, filter 16 is an LCL type filter, and thus comprises two electromagnetic coils, or filter inductors, coupled to a filter capacitor.

[0087] The electrical network 6 is an alternating current electrical network, as in the example of [Fig. 2], or alternatively a direct current electrical network. The electrical network 6 has a voltage VG and a current IG.

[0088] Each energy source 8 comprises at least one element chosen from: a photovoltaic block 20, an electric battery and a supercapacitor, not shown.

[0089] In the examples in Figures 2 and 3, each energy source 8 is formed of one or more photovoltaic blocks 20.

[0090] A "photovoltaic block" is defined as an assembly of one or more photovoltaic cells. In practice, a photovoltaic panel 22 contains numerous photovoltaic cells. A photovoltaic cell is generally configured to deliver a voltage between 0.4 V and 0.6 V, while the photovoltaic panel 22 is typically configured to deliver a voltage on the order of several tens of volts. Furthermore, it is possible to create subgroups of photovoltaic cells within the same photovoltaic panel 22, and thus to have individualized management of these subgroups of photovoltaic cells. Those skilled in the art will understand that a photovoltaic block 20 is likely to consist of a portion of a photovoltaic panel 22, that is to say, one or more subgroups of photovoltaic cells; a photovoltaic panel 22; or several photovoltaic panels 22.

[0091] In the example of [Fig.2], each energy source 8 is formed of a single photovoltaic block 20. In this example, the photovoltaic block 20 of some energy sources 8, such as the first two energy sources having elementary DC input voltages VPVi, VPV2, consists of a photovoltaic panel 22, and the photovoltaic block 20 of other energy sources 8 consists of several photovoltaic panels 22, the one associated with the last energy source of elementary DC input voltage VPVn being, for example, made up of four photovoltaic panels 22, in the form of a series connection of two groups of two photovoltaic panels 22 in parallel.

[0092] Alternatively, in the example of [Fig. 3], each energy source 8 comprises P pair(s) of photovoltaic blocks 20, the photovoltaic blocks 20 of a pair respective being connected in cascade, P being an integer greater than or equal to 1.

[0093] According to a first arrangement Al represented in the upper part of [Fig.3], the energy source 8 comprises a single pair of photovoltaic blocks 20.

[0094] According to a second arrangement A2 shown in the lower part of [Fig.3], the power source 8 comprises several pairs of photovoltaic blocks 20, in particular two pairs in this example, and the pairs of photovoltaic blocks 20 are themselves connected in cascade.

[0095] Each photovoltaic block 20 has two connection terminals 24, 26, namely a first connection terminal 24 and a second connection terminal 26; and for the cascade connection of the two photovoltaic blocks 20 of a respective pair, the first terminals 24 of the two blocks are connected to each other via a first switch 28, such as switch K5 in the first arrangement Al, the first terminal 24 of one block is connected to the second terminal 26 of the other block via a second switch 30, such as switch K6 in this first arrangement Al, and the second terminals 26 of the two blocks are connected to each other via a third switch 32, such as switch K7 in this first arrangement Al.

[0096] According to the second arrangement A2, a first pair of photovoltaic blocks 20 is referenced SGI, and a second pair of photovoltaic blocks 20 is referenced SG2. In this example, for the first pair SGI, the first switch 28 connecting the first terminals 24 of the two blocks is denoted Ki5, the second switch 30 connecting the first terminal 24 of one block to the second terminal 26 of the other block is denoted Ki6, and the third switch 32 connecting the second terminals 26 of the two blocks of said first pair SGI is denoted Kn. For the second SGI pair, the first switch 28 connecting the first terminals 24 of the two blocks is noted K25, the second switch 30 connecting the first terminal 24 of one block to the second terminal 26 of the other block is noted K26, and the third switch 32 connecting the second terminals 26 of the two blocks of said first SGI pair is noted K27.

[0097] Furthermore, according to this second arrangement A2, the two pairs SGI, SG2 of photovoltaic blocks 20 are themselves cascaded. By analogy with the cascaded connection of two photovoltaic blocks 20 described above, each pair SGI, SG2 of photovoltaic blocks itself has two connection terminals 24, 26, namely a first connection terminal 24 and a second connection terminal 26; and for the cascaded connection of the two pairs SGI, SG2, the first terminals 24 of the two pairs SGI, SG2 are connected to each other via the first switch 28, such as switch K5 in the second arrangement A2, the first terminal 24 of the SGI pair is connected to the second terminal 26 of the SG2 pair via the second switch 30, such as switch K6 in this second arrangement A2, and the The second terminals 26 of the two pairs SGI, SG2 are connected to each other via the third switch 32, such as switch K7 in this second arrangement A2.

[0098] The person skilled in the art will understand that this principle of cascaded connection is generalizable and applicable in the same way to two sets of two pairs of photovoltaic blocks 20, to obtain two sets connected in cascade, with said two sets comprising in total eight cascaded photovoltaic blocks 20; and so on.

[0099] The energy converter 10 comprises several energy conversion modules 35, each capable of receiving at its input an elementary DC input voltage Vpvn, Vpv2, Vpvn from a respective energy source 8 and of delivering at its output an elementary output voltage VHi, VH2, VHn. The elementary DC input voltage is generally denoted VPVi, and the elementary output voltage is generally denoted VHi, with i being an integer index from 1 to N, where N represents the number of energy conversion modules 35, as illustrated in the examples of Figures 2 and 3. The conversion modules 35 are connected in series by their outputs, and the total output voltage Vs is then equal to the sum of the elementary output voltages VHi, VH2, VHn. Each conversion module 35 has several switches 38 for converting the respective elementary DC input voltage into the elementary output voltage respective.

[0100] The energy converter 10 then presents, for example, a CHBMLI topology (from the English Cascaded H-Bridge Multilevel Inverter).

[0101] When the electrical network 6 is an alternating current electrical network, as in the example in [Fig. 2], as well as in that of [Fig. 3], the power converter 10 is then a direct current-alternating current converter, also denoted DC-AC, configured to convert the plurality of elementary DC input voltages VPVi, VPV2, ..., VPVn into the total output voltage Vs, which is then an alternating current voltage. Each power conversion module 35 is then also a DC-alternating current conversion module configured to convert each respective elementary DC input voltage VPVi into the respective elementary output voltage VHi, which is then an alternating current voltage.

[0102] Alternatively, when the electrical network 6 is a direct current electrical network, the energy converter 10 is then a direct current-direct current converter, also denoted DC-DC, configured to convert the plurality of elementary DC input voltages VPVi, VPV2, VPVn into the total output voltage Vs, which is then a direct current voltage. Each energy conversion module 35 is then also a direct current-direct current conversion module configured to convert each respective elementary DC input voltage VPVi into the respective elementary output voltage VHi, which is then a direct current voltage.

[0103] The electronic control device 15 comprises several elementary controllers 40 and a main controller 50 connected to each of the elementary controllers 40. In the example of Figures 1 and 4, the main controller 50 is connected to the elementary controllers 40 via a data bus 52. In other words, the main controller 50 and each of the elementary controllers 40 are connected to the data bus 52. Alternatively, not shown, each elementary controller 40 is connected to the main controller 50 via a point-to-point connection, also called a point-to-point link.

[0104] In the examples in Figures 2 and 3, each conversion module 35 comprises two input terminals 54, two output terminals 56, a switching bridge 58 with several switching branches 60, each connected between the two input terminals 54 and comprising several switches 38 connected in series and linked together a midpoint 62 connected to a corresponding output terminal 56.

[0105] In addition, each conversion module 35 further includes a capacitor 64 connected between the input terminals 54, in parallel with the switching bridge 58.

[0106] In the examples in Figures 2 and 3, the switching bridge 58 is an H-bridge, and therefore comprises two switching branches 60, as known per se. Each switching branch 60 typically comprises two switches 38 connected in series, and the switching bridge 58 therefore comprises four switches 38, also denoted Ki, K2, K3, K4, as shown in [Fig. 3].

[0107] In the example of [Fig. 3], where each energy source 8 comprises P pair(s) of photovoltaic blocks 20, each conversion module 35 comprises Q capacitors 64, where Q, equal to twice the number P, represents the number of photovoltaic blocks 20 for the energy source 8 associated with the conversion module 35, each capacitor 64 being suitable for being connected in parallel with a respective photovoltaic block 20. In this example, the Q capacitors 64 advantageously have substantially the same capacitance.

[0108] Each switch 38 is preferably a bidirectional voltage switch. Each switch 38 comprises, for example, a transistor 66 and a diode 68 connected in antiparallel to the transistor 66, as shown in [Fig. 2]. The transistor 66 is, for example, an insulated-gate field-effect transistor, also known as a MOSFET (Metal Oxide Semiconductor Field Effect Transistor). Alternatively, the transistor 66 is a bipolar transistor; an insulated-gate bipolar transistor, also known as an IGBT (Insulated Gate Bipolar Transistor); a silicon (Si)-based transistor; a GaN-based transistor; a silicon carbide (SiC)-based transistor; a diamond-based transistor; a thyristor; or a mechanical switch, such as a MEMS (MicroElectroMechanical System) microswitch. Similarly, The first, second, and third switches 28, 30, 32 also include a transistor and a diode connected in antiparallel to the transistor, which are not shown. The transistor in each of the first, second, and third switches 28, 30, 32 is, according to one of the examples described previously for transistor 66, of the same type as that of transistor 66.

[0109] Each elementary controller 40 is associated with a respective conversion module 35, and is configured to control the switches 38 of said conversion module 35.

[0110] Each elementary controller 40 is configured to regularly measure values ​​of a set of elementary quantity(ies) for the respective conversion module 35 to which it is associated, and then to transmit them to the main controller 50.

[0111] The set of elementary quantity(ies) comprises the respective elementary DC input voltage VPVi. Regular measurement of the respective elementary DC input voltage VPVi is carried out via a voltage sensor, not shown, for each respective conversion module 35, each voltage sensor being connected to the corresponding elementary controller 40.

[0112] As an optional addition, the set of elementary quantity(ies) includes a respective elementary input DC current IPVi, from the corresponding energy source 8. According to this optional addition, the regular measurement of the respective elementary input DC current IPVi then requires the presence of a current sensor, not shown, for each respective conversion module 35, each current sensor being connected to the corresponding elementary controller 40.

[0113] Each elementary controller 40 typically includes a control unit 70 configured to control the switching bridge 58 by operating the switches 38. Optionally, each elementary controller 40 includes a determination unit 72 configured to determine an optimal voltage Voptj associated with the respective conversion module 35. The determination unit 72 is typically configured to determine said optimal voltage Voptj by implementing a maximum power point tracking (MPPT) algorithm.

[0114] Each elementary controller 40 also includes a receiver 74 and a transmitter 76, each compatible with the communication protocol of the data bus 52. That is to say, the receiver 74 is capable of receiving data from the main controller 50 via the data bus 52, in particular a connection coefficient K; indicating whether or not it is necessary to connect the respective power source 8 to the corresponding conversion module 35 in order to subsequently deliver the respective elementary output voltage VHi. The transmitter 76 is capable of regularly transmitting data to the main controller 50 via said bus 52, in particular a measured value of the respective elementary input DC voltage VPVi, the value of the voltage optimal Vopt i, or even a measured value of the respective elementary input direct current IPVi.

[0115] The main controller 50 is configured to perform regulation of an output quantity of the energy converter 10 by sending control commands to the elementary controllers 40, the regulation being performed according to the sets of elementary quantity(ies), each set of elementary quantity(ies) being associated with a respective conversion module 35.

[0116] The output quantity of the energy converter 10 that is regulated by the main controller 50 is typically the output voltage Vs or an output current Is of the energy converter 10. If the energy converter 10 is connected to a voltage-dependent load, such as the electrical network 6, then the regulated quantity, i.e., the quantity to be controlled, is the output current Is. Conversely, if the energy converter 10 is connected to a current-dependent load, such as a motor or a battery charger(s), then the quantity to be controlled is the output voltage Vs.

[0117] The regulation carried out by the main controller 50 is implemented within a control unit REG, described in more detail later with reference to [Fig.4].

[0118] According to the invention, the main controller 50 includes a first estimator 80, visible in Figure 1, configured to calculate, for each conversion module 35, an estimated value pÇL ( f of the elementary DC input voltage VPVi from a previously measured value VPVi (tk_p) of the elementary DC input voltage VPVi.

[0119] As an optional addition, the main controller 50 further includes a second estimator 85 configured to calculate, for each conversion module 35, an estimated average <ipvi>of the elementary IPVi input current received by the conversion module 35, the estimated average <ipvi>The elementary input current IPVi is then used to calculate the estimated value of the DC voltage. VPVi entry comment.

[0120] According to this optional addition, by estimating the elementary input current IPVi via the second estimator 85, it is not necessary to measure the respective elementary input current IPVi, and this avoids the need to add a current sensor for each respective conversion module 35. According to this optional addition, the set of elementary quantity(ies), measured regularly for each elementary controller 40, then comprises only the respective elementary DC input voltage VPVi.

[0121] As an optional addition, the main controller 50 further includes a third estimator 90 configured to calculate, for each conversion module 35, a estimated value (J^, of the capacitance CPVi of capacitor 64.

[0122] In the example of [Fig.1], the first estimator 80, as well as optionally the second estimator 85 and the third estimator 90, are each implemented in the form of a programmable logic component, such as an FPGA (Field Programmable Gate Array) or an integrated circuit, such as an ASIC (Application Specifies Integrated Circuit).

[0123] Alternatively, the main controller 50 includes an information processing unit formed for example of a memory and a processor associated with the memory, not shown.

[0124] According to this variant, the first estimator 80, as well as optionally the second estimator 85 and the third estimator 90, are each implemented as a software program, or a software component, executable by the processor. The memory of the main controller 50 is then capable of storing a first estimation program capable of calculating, for each conversion module 35, the estimated value y^- ( tk ) of the elementary input DC voltage VPVi from the previously measured value VPVi(tk-p) of the elementary input DC voltage VPVi. Optionally, the memory of the main controller 50 is then capable of storing a second estimation program capable of calculating, for each conversion module 35, the estimated average <ipvi>of the elementary input current IPVi received by the conversion module 35, and a third estimation software capable of calculating, for each conversion module 35, the estimated value of the capacitance CPVi of the capacitor 64. The processor of the main controller 50 is then capable of executing each of the following software programs: the first estimation software, and optionally the second and third estimation software programs. Those skilled in the art will further understand that when executed by said processor, the first estimation software, and optionally the second and third estimation software programs, then respectively form the first estimator 80, the second estimator 85, and the third estimator 90.

[0125] When the main controller 50 is implemented in the form of one or more software programs, i.e., in the form of a computer program, also called a computer program product, it is further capable of being stored on a computer-readable medium, not shown. A computer-readable medium is, for example, a medium capable of storing electronic instructions and being connected to a bus of a computer system. By way of example, a readable medium is an optical disc, a magneto-optical disc, ROM, RAM, any type of non-volatile memory (e.g., EPROM, EEPROM, FLASH, NVRAM), a magnetic card, or an optical card. A computer program comprising software instructions.

[0126] The data bus 52, also called the communication bus, is, for example, an RS-485 bus (the RS-485 standard is also known as EIA-485); a USB (Universal Serial Bus); a UART (Universal Asynchronous Receiver Transmitter); or a CAN (Controller Area Network) bus, standardized by ISO 11898. The communication bus 52 then has a limited data rate, primarily for reliability reasons. In a conversion system 5 with a significant number of conversion modules 35, typically more than five, the amount of data to be transmitted in real time via the communication bus 52 can be substantial. Therefore, the operating frequency of the power converter 10 may be limited by the data acquisition time.

[0127] For the CHBMLI topology, the conversion modules 35 are advantageously connected to the back of the photovoltaic panels 22 so as to limit the length of an electrical cable 92, also called a power cable, connecting the outputs of the conversion modules 35 in series, i.e., one after the other. Thus, the communication bus 52 runs the length of the surface of the photovoltaic panels 22 (up to 20 meters for a converter 10 of several kW, connected to the network 6). For communication, a UART protocol is used, for example, with a physical layer conforming to the RS-485 standard. This UART protocol is simple to implement and allows communication from one master to several slaves. The RS-485 standard defines the transmission of signals on the bus in differential mode.Over long distances (greater than a few meters), this significantly reduces parasitic effects and errors, while maintaining an acceptable data rate for the conversion system 5 (4 Mbit / s). The conversion modules 35 are, for example, all referenced to different potential points and are thus electrically isolated from each other. Since the communication bus 52 is shared with all the conversion modules 35, a galvanic isolation circuit, not shown, is used to exchange data between the elementary controllers 40 and the communication bus 52. This galvanic isolation function is, for example, directly integrated into RS-485 communication units. Other isolation solutions are possible, such as the use of optocouplers, or specialized circuits with integrated isolation (for example, the ADUM3472ARSZ offered by Analog Devices™).

[0128] Communication via the data bus 52 between the different elements of the conversion system 5 is done for example in "Full-Duplex" mode, that is to say there is a dedicated line for reception, a dedicated line for transmission, the two lines being usable simultaneously.

[0129] Alternatively, communication via the data bus 52 between the different elements of the conversion system 5 is carried out in "Half-Duplex" mode where only one communication line is used. Transmission and reception are then temporally interleaved. This saves on the communication bus 52 (fewer conductors in the bus 52). On the other hand, the data rate is reduced (transmission and reception cannot take place simultaneously).

[0130] The REG control unit comprises a receiver 94 and a transmitter 96, each compatible with the communication protocol of the data bus 52. In other words, the receiver 94 is capable of receiving data from each of the elementary controllers 40 via the data bus 52, in particular the measured values ​​of the elementary DC input voltages VPVi, VPV2, VPVn, the values ​​of the optimal voltages Vopt_i, Vopt 2, ..., Vopt N, and even the measured values ​​of the elementary DC input currents IPVi, IPv2, IPvn. The transmitter 96 is capable of regularly transmitting data to the elementary controllers 40 via said bus 52, in particular the connection coefficients Kb K2, ..., KN.

[0131] For the regulation of the output quantity, the REG control unit typically includes a first control loop of a first type of quantity, followed by a second control loop of a second type of quantity, distinct from the first type.

[0132] In the example of [Fig.2] where the power converter 10 is connected to the electrical network 6, the regulated output quantity is the output current Is, and the first regulation loop is a voltage regulation loop, the second regulation loop being a current regulation loop.

[0133] In the example of [Fig.4] associated with this example of [Fig.2], the first regulation loop includes an adder 98 capable of making the difference between the sum of the values ​​of the elementary DC input voltages VPVi, VPV2, • VPVn and the sum of the values ​​of the optimal voltages Vopt_i, Vopt 2, ..., Vopt N; followed by an averager 100, in order to compare the average of the elementary DC input voltages VPVi, VPV2, ..., VPVn with the average of the optimal voltages Vopt_i, Vopt2, ..., VoptN. Additionally, the first loop includes a controller 102 connected to the output of the averager 100 to cancel the error between the average of the elementary DC input voltages VPVi, VPV2, ..., VPVn and that of the optimal voltages Vopt_i, Vopt2, ..., VoptN in steady state. The controller 102 is, for example, a proportional-integral controller, also called a PI controller.Alternatively, controller 102 is a proportional-integral-derivative type controller, also known as a PID controller.

[0134] Advantageously, the first control loop also includes a filter 104, such as a band-stop filter around a frequency substantially equal to 100 Hz for a 50 Hz network (or 120 Hz for a 60 Hz network). Indeed, the modules of The conversion modules 35 produce direct current (DC) power, while the output power, on the electrical grid 6, is alternating current (AC). This means that, over a half-cycle of the grid (100 Hz or 120 Hz), when the instantaneous output power is less than (respectively greater than) the sum of the powers of the conversion modules 35, the excess energy is stored (respectively released) by the capacitors 64 of the conversion modules 35. Over a half-cycle of the grid and in steady state, each capacitor 64 has stored as much energy as it has released. This causes a natural oscillation at 100 Hz on the voltage of the energy sources 8, such as the photovoltaic arrays 20, the amplitude of which is inversely proportional to the value of the capacitor 64 and proportional to the elementary DC input current IPVi from the energy source 8, for example, from a photovoltaic array 20.This oscillation is then suppressed by filter 104 to prevent it from appearing on a reference current Iref delivered at the output of the first regulation loop.

[0135] To obtain a sinusoidal reference current Iref, the first control loop advantageously includes a Phase-Locked Loop (PLL) unit 106, also called a PLL unit (from the English "Phase Locked Loop"), which receives as input the voltage VG of the electrical network 6, as well as the current IG of said network 6. The PLL unit 106 is then connected to the input of a sine function 108 to generate a term in sin(ωG / + φG), that is to say, a sinusoidal function of unit amplitude in phase with the network voltage VG. Other mechanisms are conceivable for obtaining this sinusoidal function of unit amplitude in phase with the network voltage VG, for example by dividing the network voltage VG by its amplitude.

[0136] The first regulation loop finally includes a multiplier 110 connected, on the one hand, to the output of the filter 104, and on the other hand to the output of the sine function 108, in order to multiply the term in sin(mGf + 3G) with the current obtained at the output of the filter 104, to generate the reference current Iref thus made sinusoidal.

[0137] In the example of [Fig.4], the second regulation loop then aims to compare the sinusoidal reference current Iref with the current IG of said network 6, corresponding to the output current Is of the energy converter 10, the regulated output quantity being in this example the output current Is.

[0138] In this example, the second control loop includes a subtractor 112 capable of differentiating between the network current IG and the reference current Iref, followed by a regulator 114, preferably a resonant proportional type regulator, also called a PR regulator, which makes it possible to cancel the setpoint tracking error even with a sinusoidal reference (of known frequency).

[0139] The second control loop then includes a linearization block 116 connected to the output of regulator 114, the linearization block 116 includes an adder 118 to sum the mains voltage VG at the output of regulator 114, followed by a divider 120 to divide this sum by the average of the elementary DC input voltages VPVi, VPV2, • VPVn-

[0140] The second control loop includes a sorting unit 122 connected to the output of the linearization block 116. This sorting unit 122 implements a sorting algorithm that selects which energy sources 8 will be connected or not during the next control iteration. The energy sources 8 connected first are those with the largest voltage error (Vpv - Vopt) among the list of functioning energy sources 8, such as the photovoltaic blocks 20. Any faulty energy sources 8 can be excluded from operation. The sorting unit 122 is then configured to generate the connection coefficients K2, ..., Kn.

[0141] The first estimator 80 is configured to calculate, for each conversion module 35, the estimated value Vpv (tk ) of the elementary input DC voltage VPvi as a function of the previously measured value VPVi(tk-P) of the elementary input DC voltage VPVi, the capacitance CPVi of the capacitor 64 and a value of the current ICi flowing through said capacitor 64.

[0142] Advantageously, the first estimator 80 is configured to calculate the value of the current ICi flowing through said capacitor 64 by the difference between a value of an elementary input current IPVi received by the conversion module 35 and a value of a bridge current IHi received by the switching bridge 58.

[0143] The first estimator 80 is, for example, configured to calculate, for each conversion module 35, the estimated value (t A of the DC voltage ele- VPVi input comment according to the following equation:

[0144] [Math.l] VVPi(tk) = VpvSjk-l) + (ipv^k) )-T~

[0145] where ) represents the estimated value of the elementary DC input voltage VPvi,

[0146] VPVi(tk-i) represents a previous value of the elementary DC input voltage VPvi,

[0147] IPVi(tk) represents the value of the elementary input current IPVi,

[0148] tk, and respectively tk_i, represent respectively current and previous time instants,

[0149] CPvi represents the capacitance of capacitor 64, and

[0150] IHi_M(tk) represents the average value of the bridge current IHi between instants temporals tk_i and tk.

[0151] The previous value VPVi(tk_i) of the elementary DC input voltage VPVi is the previously measured value VPVi(tk_p) of the elementary DC input voltage VPVi if it was measured for the previous time instant, that is, if the previous time instant tk_i corresponds to the time instant of the previous measurement of the elementary DC input voltage VPVi, i.e., kl=kp, or p=l. Alternatively, the previous value VPVi(tk_i) of the elementary DC input voltage VPVi is the previous estimated value of the elementary DC input voltage VPVi if the previously measured value VPVi(tk p) was measured for a time instant tk p prior to the previous time instant tk_b, that is, if the previous time instant tk_i is posterior to the time instant of the previous measurement of the elementary DC input voltage VPVi, i.e. kl>kp, i.e. p>l.

[0152] A person skilled in the art will understand that the preceding equation [1] is obtained from the following equation:

[0153] [Math.2] Ipv, (f ) = le.( t ) + Ih,( t ) = Cp v.—+ J h, (t)

[0154] where IPVi represents the elementary input current,

[0155] represents the current flowing through capacitor 64,

[0156] IHi represents the current received by the switching bridge 58,

[0157] CPVi represents the capacitance of capacitor 64, and

[0158] VPVi represents the elementary DC input voltage, these quantities being visible to [Fig.2].

[0159] The average value IHi_M(tk) of the bridge current IHi satisfies, for example, the following equation:

[0160] [Math.3] 1^(^) -

[0161] where fB represents the frequency at which the regulation of the output quantity Is, Vs of the energy converter 10 is carried out by the main controller 50, i.e. the frequency of a regulation loop of said output quantity Is, Vs, described hereafter with regard to [Fig.8].

[0162] A person skilled in the art will observe that the frequency fB at which the regulation of the output quantity Is, Vs is performed by the main controller 50 also corresponds to the frequency at which the estimations of the elementary DC input voltage VPVi will be performed by the main controller 50, this frequency fB of the regulation loop being equal to the inverse of the time interval between two successive time instants tk and tk of calculation of said estimation. The frequency fB of the re loop regulation of the output quantity Is, Vs then also corresponds to the operating frequency of the main controller 50.

[0163] Those skilled in the art will note that, when the conversion module 35 is configured in positive or negative polarity, the current IHi received by the switching bridge 58, i.e., the input current of the switching bridge 58, corresponds to + / -IS, i.e., to + / -IG if the converter 10 is connected to the network 6; and when the conversion module 35 is in bypass or open mode, the current IHi received by the switching bridge 58 is zero. The output current Is, or the current IG of the network 6, is measured directly by the main controller 50 and is sampled at the frequency fB of the control loop, hereafter referred to as the loop frequency fB. Furthermore, the main controller 50 knows, at all times, the configuration of all the conversion modules 35, since it determines these configurations and then controls them, i.e., drives them, via the elementary controllers 40.The main controller 50 is therefore capable of determining the value of the current IHi received by the switching bridge 58, with sampling instants according to the loop frequency fB.

[0164] As an optional complement, the second estimator 85 is configured to calculate, for each conversion module 35, the estimated mean <ipvi>of the elementary input current IPVi over a period of average Tg, as a function of the total output voltage Vs and the output current Is delivered at the output of the energy converter 10, and of an average value <vpvi>of the elementary DC input voltage VPVi over the average duration Tg.

[0165] The average time Tg typically depends on half a period of the output voltage Vs. The average time Tg is preferably a multiple of half a period of the output voltage Vs, said multiple being an integer greater than or equal to 1. The average time Tg is preferably also substantially equal to the period of the output voltage Vs.

[0166] The second estimator 85 is, for example, configured to calculate, for each conversion module 35, the estimated mean <ipvi>of the elementary input current I PVi according to the following equation:

[0167] [Math.4] ~Tg.-----------

[0168] where <ipy>represents the estimated average of the elementary input current IPVi,

[0169] Tg represents the averaging time,

[0170] Vs represents the total output voltage,

[0171] Is represents the output current,

[0172] <Vpy> represents the average value of the elementary DC input voltage Vpvi over said average duration Tg, and

[0173] K; represents a connection coefficient, K; being equal to 0 when no energy source 8 is connected to the input of the corresponding conversion module 35, and K; being different from 0 when at least one energy source 8 is connected to the input of said module 35.

[0174] When the energy source 8 is formed of a single photovoltaic block 20, as in the example of [Fig.2], the associated connection coefficient K; is equal to +1 when the conversion module 35 is connected in positive polarity, equal to -1 when the conversion module 35 is connected in negative polarity, and equal to 0 when the conversion module 35 is disconnected (bypass or open).

[0175] When the energy source 8 is formed of several photovoltaic blocks 20, as in the example of [Fig.3], the associated connection coefficient K; is - when it is non-zero - a multiple of 1 / Q, where Q represents the number of photovoltaic blocks 20 for the energy source 8 associated with the conversion module 35. The multiple is a relative integer, i.e. a positive or negative integer, the value of which depends on a connection configuration of the photovoltaic blocks 20 and a connection state of each of the photovoltaic blocks 20, each connection state being among connected and disconnected.

[0176] Examples of the value of the connection coefficient K; associated with an energy source 8 formed of several photovoltaic blocks 20 are described below opposite Table 1 in the example of the first arrangement Al of [Fig.3], and opposite Table 2 in the example of the second arrangement A2 of this [Fig.3].

[0177] The third estimator 90 is configured to estimate a current value of the CPVi capacitance of capacitor 64.

[0178] The CPVi capacitance value of capacitor 64 is typically supplied by the manufacturer of said capacitor 64 with a tolerance of up to + / - 30%, and this CPVi capacitance varies over time. It is therefore advantageous to estimate, using the third estimator 90 and with greater accuracy, its value during the operation of the power converter 10.

[0179] The third estimator 90 is typically configured to estimate a current value of the capacitance CPVi of the capacitor 64 by correcting a previous estimated value of the capacitance CPVi of the capacitor 64 as a function, on the one hand, of the sign of the difference between a value of a bridge current IHi received by the switching bridge 58 and a value of an elementary input current IPVi received by the conversion module 35, called the first sign; and on the other hand, of the sign of the difference between the estimated value tj of the elementary input DC voltage VPVi and the subsequently measured value VPVi(tk+i) of the elementary input DC voltage VPVi, called the second sign; an initial estimated value of the CPVi capacitance of capacitor 64 being predefined.

[0180] If the first and second signs are identical, the current estimated value of the CPVi capacitance of capacitor 64 is, for example, equal to the previous estimated value of the CPVi capacitance of capacitor 64 less one ACPVi correction step; and if the first and second signs are different, the current estimated value of the CPVi capacitance of capacitor 64 is, for example, equal to the previous estimated value of the CPVi capacitance of capacitor 64 increased by the ACPVi- correction step.

[0181] The ACPVi correction step is, for example, on the order of a percent of the initial value of the CPVi capacitance of capacitor 64.

[0182] In other words, the principle of the third estimator 90 is to compare the estimated data with the real data reported by the communication bus 52. Indeed, the value of the capacitance CPVi of the capacitor 64 is the only data of equation (2) or of equation (1) which is not perfectly known, at the beginning of the operation of the energy converter 10. Thus, when the main controller 50 receives a new measured value of the elementary DC input voltage VPVi, it will compare the voltage which it has estimated (thanks to its first estimator 80) with the measured one.

[0183] There are then several cases to consider:

[0184] - If

[0185] + if the estimated voltage is greater than the actual voltage, then the capacitance value CPVi of capacitor 64 (taken into account in equation (1)) is too large compared to the actual value;

[0186] + if the estimated voltage is less than the actual voltage, then the capacitance value CPVi of capacitor 64 (taken into account in equation (1)) is too low compared to the actual value.

[0187] -SiIH.(tk)-Ipv^k)

[0188] + if the estimated voltage is less than the actual voltage, then the capacitance value CPVi of capacitor 64 (taken into account in equation (1)) is too large compared to the actual value;

[0189] + if the estimated voltage is greater than the actual voltage, then the capacitance value CPVi of capacitor 64 (taken into account in equation (1)) is small compared to the actual value.

[0190] - If the estimated voltage is equal to the actual voltage, then the value of the capacitance CPVi of capacitor 64 (taken into account in equation (1)) is equal to the real value.

[0191] The algorithm for correcting the value of capacitor 64 by successive steps allows the actual value of the capacitance CPVi of each capacitor 64 in the conversion system 5 to be quickly recovered (in a few periods of the mains voltage VG). This offers Several advantages are offered. First, it improves the initial estimator 80 by providing better accuracy in estimating the elementary DC input voltage VPVi. Second, it allows for monitoring the evolution of passive components in the conversion modules 35. Indeed, in a power electronics converter, capacitors are often the most fragile components, and their aging is generally characterized by a gradual decrease in their actual capacitance value. This third estimator 90 therefore makes it possible to anticipate future failures and target repairs.

[0192] In the example of the first arrangement Al in [Fig. 3], the conversion module 35 is coupled to two photovoltaic blocks 20, denoted Pai and Pbi, which are dynamically configurable in series or parallel, depending on the state of the first, second, and third switches 28, 30, 32. The two photovoltaic blocks Pai and Pbi and the two capacitances CPVai and Cpvbi of the corresponding capacitors 64, connected between the terminals of the photovoltaic blocks Pai and Pbi, are considered identical or nearly identical. The behavior of the photovoltaic block Pai with the capacitance CPVai and of the photovoltaic block Pbi with the capacitance CPVbi are therefore considered substantially identical, with similar currents Lai and Lbi, similar IPVai and IPVbi, and similar voltages VPVai and VPVbi.The elementary DC input voltage VPVi is then a linear combination of the voltages VPVai and Vpvbi across the two photovoltaic blocks 20, typically written in the form VPVi = aVPVai + PVPVbi, with a and α representing the coefficients of the linear combination. The linear combination of the voltages VPVai and VPVbi is, for example, the average value of the voltages VPVai and VPVbi (a α = 1 / 2), or the value of one of the voltages VpVai and Vpvbi of the photovoltaic blocks 20 (a = 1 and α = 0) to limit the number of measurements, the two voltages VPVai and VPVbi being similar.

[0193] In the case of an estimation of the capacitance CPVi of capacitor 64, it is then considered that this estimated value corresponds to a weighting of the two capacitances Cpvi = aCPVai + [3Cpvbi], with a and [3] being the aforementioned coefficients of the linear combination of the voltages VPVai and VPVbi to determine the elementary DC input voltage VPVi. The estimated value of the capacitance CPVi of capacitor 64 then typically corresponds to the value of one or the other of the two capacitances CPVai and CPVbi of the corresponding capacitors 64, or to an average value of the two capacitances CPVai and CPVbi.

[0194] Those skilled in the art will note that it is possible to short-circuit a photovoltaic unit 20 to disable its use, for example, following a failure in the respective photovoltaic unit 20. In the example of the first arrangement A1 of [Fig. 3], to short-circuit the photovoltaic unit P1, switches K5 and K6 must be closed; and to short-circuit the photovoltaic unit P2, switches K6 and K7 must be closed. If one photovoltaic unit 20 is short-circuited, it is then possible to continue operating with the other photovoltaic unit 20 according to the embodiment example of the [Fig.2], described previously, where each energy source 8 is formed from a single photovoltaic block 20.

[0195] Table 1 below then presents the main configurations of the first arrangement Al of [Fig. 3], as well as the corresponding value of the connection coefficient of each photovoltaic block 20, here denoted KPPi, instead of the notation K; used in the case of a single photovoltaic block 20. This connection coefficient KPPi links the elementary input DC current VPVi to the grid current Ig-

[0196] [Tables 1] Configuration / State List of closed switches Kpv, Series+Positive polarity K6 and K2, K3 IG 1 Parallel+Positive polarity K5, K7 and K2, K3 7C 2 1 / 2 Bypass / bypass Kl, K3 or K2, K4 0 0 All open Configuration that tends to drop IG towards zero -kd w Parallel+Negative polarity K5, K7 and Kl, K4 G 2 -1 / 2 Series+Negative polarity K6 and Kl, K4 -Zo -1

[0197] In the example of the second arrangement A2 of [Fig. 3], the module contains four photovoltaic blocks 20, labeled Pali, Pbli, Pa2i, and Pb2i. Within the first pair SGI, the photovoltaic blocks PaH and Pbü; and respectively within the second pair SG2, the photovoltaic blocks Pa2i and Pb2i, are dynamically configurable in series or parallel, depending on the state of the first, second, and third switches 28, 30, and 32, respectively. The two pairs SGI and SG2 are themselves dynamically configurable in series or parallel, depending on the state of the first, second, and third switches 28, 30, and 32, respectively, interconnecting these two pairs SGI and SG2, i.e., switches K5, K6, and K7.Finally, the output of the conversion module 35 according to the second arrangement A2 is likely to be in positive polarity, negative polarity, bypass, or fully open, depending on the state of the switches 38, i.e., switches Kh K2, K3, and K4, of the switching bridge 58 of said conversion module. Analogously to what was described previously for the first arrangement A1, the photovoltaic blocks PaH, PbH, Pa2i, and Pb2i and the... The respective capacities CPVaii, CPVbii, CPVa2i, and CPVb2i are considered identical or close. The behavior of the photovoltaic blocks with their respective capacitor capacities 64 is therefore considered substantially identical, with similar currents Ici and IPVi and similar voltages VPVi. Thus, the elementary DC input voltage VPVi can be measured on one of the four photovoltaic blocks 20 (for example, VPVi = VPV2ai), or obtained by averaging the voltages of the four photovoltaic blocks 20 for a better accounting of potential variations (VPVi = (VPViai + VPVibi + VPV2ai + VPV2bi) / 4). More generally, the elementary DC input voltage VPVi is any linear combination of the individual voltages of the four photovoltaic blocks 20, typically written in the form V PVi= (17^+ |3VPVibi+ vVPV2ai+ ôVPV2bi, with a, [3, y and ô representing the coefficients of the linear combination.Furthermore, if one of the 20 photovoltaic blocks fails, it can be bypassed, and its voltage is then ignored.

[0198] In the case of an estimation of the CPVi capacitance of capacitor 64, it is then considered that this estimated value corresponds to any linear combination of the individual capacitances, typically written in the form CPVi= aCPViai+ [3CPVibi + yCPV2ai+ ôCPV2bi, with a, [3, y and ô representing the coefficients of the linear combination, according to the weighting which was used to determine the CPVi capacitance.

[0199] Those skilled in the art will note that it is possible to short-circuit a photovoltaic unit 20 to disable its use, for example, following a failure in the respective photovoltaic unit 20. In the example of the second arrangement A2, short-circuiting a photovoltaic unit 20 requires closing two switches; for example, closing Ki5 and Ki6 to short-circuit the photovoltaic unit PaH, or closing Ki6 and Kn to short-circuit the photovoltaic unit Paib; and similarly for the second pair SG2. The other photovoltaic units 20 remain usable.

[0200] Table 2 below then presents the main configurations of the second arrangement A2 of [Fig. 3], as well as the corresponding value of the connection coefficient of each photovoltaic block 20, here denoted KVPi, instead of the notation K; used in the case of a single photovoltaic block 20. This connection coefficient KVPi links the elementary input DC current VPVi to the grid current Ig-

[0201] [Tables2] Configuration / Status List of closed switches IpVj Kpv{ (SGI series) series (SG2 series) and polarity + K16, K6, K26 and K2, K3 Ig 1 (SGI / / ) series (SG2 series) and polarity + alternating at 50% with (SGI series) series (SG2 / / ) and polarity + K15, K17, K6, K26 and K2, K3 K16, K6, K25, K27 and K2, K3 3 G 4 3 / 4 (SGI / / ) series (SG2 / / ) and polarity + K15, K17, K6, K25, K27 and K2, K3 G 1 / 2 (SGI series) / / (SG2 series) and polarity + K16, K5, K7, K26 and K2, K3 G 2 1 / 2 (SGI / / ) / / (SG2 / / ) and polarity + K15, K17, K5, K7, K25, K27 and K2, K3 G 4 1 / 4 (SGI / / ) / / (SG2 series) or (SGI / / ) / / (SG2 series) Forbidden configurations Bypass / bypass K1, K3 or K2, K4 and any configuration 0 0 All open Configuration that tends to drop IG towards zero -G (SGI / / ) / / (SG2 / / ) and polarity - K15, K17, K5, K7, K25, K27 and K1, K4 [g 4 -1 / 4 (SGI series) / / (SG2 series) and polarity - K16, K5, K7, K26 and K1, K4 G 9 -1 / 2 (SGI / / ) series (SG2 / / ) and polarity - K15, K17, K6, K25, K27 and K1,K4 G 9 -1 / 2 (SGI / / ) series (SG2 series) and polarity alternating at 50% with (SGI series) series (SG2 / / ) and polarity - K15, K17, K6, K26 and Kl, K4 K16, K6, K25, K27 and Kl, K4 3 G 4 -3 / 4 (SGI series) series (SG2 series) and polarity - K16, K6, K26 and Kl, K4 -Ig -1 , (SGI) series (SG2 series) and polarity + K15, K16, K6, K26 and K2, K3 1 (SGI) series (SG2 / / ) and polarity + alternating at 50% with (SGI isolated) / / (SG2 series) and polarity + K15, K16, K6, K25, K27 and K2, K3 K15, K16, K7, K26 and K2, K3 2 1 / 2 (SGI) / / (SG2 / / ) and polarity + K15, K16, K5, K7, K25, K27 and K2, K3 k 1 / 3 Bypass / bypass K1, K3 or K2, K4 and any configuration 0 0 (SGI) / / (SG2 / / ) and polarity - K15, K16, K5, K7, K25, K27 and K1, K4 h ' 3 -1 / 3 (SGI) series (SG2 / / ) and polarity - alternated at 50% with (SGI isolated) / / (SG2 series) and polarity - K15, K16, K6, K25, K27 and K1, K4 K15, K16, K7, K26 and K1, K4 G' 2 - 1 / 2 (SGI) series (SG2 series) and polarity - K15, K16, K6, K26 and K1, K4 -Ig -1

[0202] The operation of the electronic control device 15, and in particular of the main controller 50, according to the invention will now be described with reference to [Fig.5] representing a flowchart of the control method of the electrical energy converter 10 according to the invention, the control method being implemented by a main controller 50.

[0203] During an initial step 100, the main controller 50 calculates, via its first estimator 80 and for each conversion module 35, an estimated value y^) / j of the elementary input DC voltage VPVi from a previously measured value VPVi(tk-p) of the elementary input DC voltage VPVi.

[0204] The estimated value j of the elementary DC input voltage VPVi is by example calculated according to the previous equation (1).

[0205] As an optional addition, during this initial step 100, the main controller 50 also calculates, via its second estimator 85 and for each conversion module 35, the estimated average <ipvi>of the elementary input current IPVi. Said estimated average <ipvi>is then used to calculate the estimated value of the elementary DC input voltage VPVi, and thus avoids the addition of a current sensor for each respective 35 conversion module.

[0206] Said estimated average <ipvi>is for example calculated according to the previous equation (4).

[0207] As an additional optional complement, during this initial step 100, the main controller 50 also estimates, via its third estimator 90 and for each conversion module 35, a current value of the capacitance CPVi of the capacitor 64. This additional optional complement makes it possible to further improve the estimation of the elementary DC input voltage VPVi.

[0208] The third estimator 90 typically estimates the current value of the capacitance CPVi of the capacitor 64 by correcting a previous estimated value of the capacitance CPVi of the capacitor 64 as a function, on the one hand, of the sign of the difference between a value of a bridge current IHi received by the switching bridge 58 and a value of an elementary input current IPVi received by the conversion module 35, called first sign; and on the other hand, of the sign of the difference between the estimated value vÇy ( tk ) of the elementary input DC voltage VPVi and the subsequently measured value VPVi(tk+i) of the elementary input DC voltage VPVi, called second sign; the initial estimated value of the capacitance CPVi of the capacitor 64 being predefined.

[0209] Following this step 100 of estimating the elementary DC input voltage VPVi, the main controller 50, in a subsequent step 110 and via its control unit REG, regulates the output quantity Is, Vs of the power converter 10 by sending control commands to the elementary controllers 40. The regulation is performed based on sets of elementary quantity(ies), each set of elementary quantity(ies) being associated with a respective conversion module 35. The set of elementary quantity(ies) includes, in particular, the elementary DC input voltage VPVi, and the value of the elementary DC input voltage VPVi taken into account for this regulation is then a value measured by the elementary controller 40 when it has just been measured, and otherwise the estimated value calculated by the first estimator 80.

[0210] For the purposes of this regulation step 110, each elementary controller 40 regularly measures values ​​of the set of elementary quantities for the respective conversion module 35 to which it is associated, and then transmits them to the main controller 50, as described previously with regard to [Fig.4].

[0211] The piloting process is then repeated by returning to the estimation step 100 at the end of the regulation step 110, the piloting process being implemented periodically, typically at the loop frequency fB, for example of the order of 20 kHz.

[0212] As described previously, the REG control unit takes as input the data from the photovoltaic blocks 20 (VPV and Vopt of each photovoltaic block 20) ​​as well as The network data (VG and IG) are used to determine the control commands. To properly regulate the input (VPVi voltages of the photovoltaic blocks 20) and output (network current IG) quantities, it is preferable to choose a loop frequency fB significantly higher than the grid frequency fG 6, i.e., fB > fG. Furthermore, increasing this frequency allows for a reduction in the size of the output filter 16, as well as improved regulation of the parameters (Total Harmonic Distortion, power factor). The chosen value for the loop frequency fB is, for example, around 20 kHz, which allows the control of the converter 10 according to the invention to be compared with that of commercially available inverters while maintaining very good performance (regulation and filter size). Data management is summarized in Table 3 below.The measurements of network voltage and current (VG and IG) do not impose constraints on the communication bus 52, as they are measured in real time directly by the main controller 50; the acquisition frequency depends only on the capabilities of the main controller 50. The optimal voltages Vopt_i (calculated, for example, via the implementation of the MPPT algorithm) evolve slowly as a function of sunlight and temperature. It is therefore possible to transmit this information at a low frequency, i.e., f^ippy « fp, where fMPPT represents the calculation frequency according to the MPPT algorithm.

[0213] On the other hand, the elementary DC input voltages VPVi should advantageously be sent in real time to the main controller 50 in order to allow for proper regulation of these quantities. However, the constraints of the communication bus 52 limit the refresh rate fD of this data.

[0214] [Tables3] Data Refresh rate Acquisition type A Direct measurement by the main controller 50 VG fB Direct measurement by the main controller 50 optf Vopt-f •••, Optn f J MPPT Communication bus 52 Vpv? Ppv,, Vpv„ f D Communication bus 52

[0215] As an example for the communication bus 52, the RS-485 physical layer offers a data rate limited to 4 Mbit / s. This limitation arises from the distance traveled by the signals in the cables between the main controller 50 and the elementary controller 40 the furthest. With such a data rate, the data refresh rate fD is given by the following equation:

[0216] [Math.5] f N *({n bits + n CRC ) + t D r)

[0217] where fD represents the data refresh rate, (expressed in Hz);

[0218] nbits represents the number of bits transferred including the Start and Stop bits, expressed in bits;

[0219] nCRc represents the number of bits in the CRC frame (from the English Cyclic Redundancy Check expressed in bits;

[0220] DUArt represents the communication bus rate 52, expressed in Mbit / s; and

[0221] tDT represents the waiting time between two frames on communication bus 52, expressed in ps. This waiting time helps to avoid collisions on communication bus 52 which would lead to a fault.

[0222] By way of example, the values ​​chosen for the aforementioned parameters of the communication bus 52 are summarized in Table 4 below. With these parameters specified, the refresh rate fD is limited to 2.5 kHz, or about one-tenth of the desired operating frequency, the loop frequency fB being on the order of 20 kHz.

[0223] [Tables4] Data Details Value N Number of modules 13 nbits Number of data bits 20 (including 4 Start / Stop bits) nCRC Number of CRC bits 10 (including 2 Start / Stop bits) DuART UART bit rate 4 Mbit / s tüT Time between 2 frames 25 ps fD Refresh rate 2.5 kHz

[0224] Moreover, since the refresh rate fD is inversely proportional to the number N of conversion modules 35, an increase in said number N of conversion modules 35 tends to widen the gap between the refresh rate fD and the loop frequency fB even further.

[0225] The first estimator 80 then makes it possible to remedy this limitation, by calculating at the loop frequency fB the estimated value (tk) of the elementary input DC voltage VPVi, while the measured values ​​of the elementary input DC voltage VPVi are transmitted to the main controller at the refresh rate

[0226] The person skilled in the art will thus understand that, when the refresh rate fD is about one tenth of the loop frequency fB, the regulation of the output quantity Is, Vs of the energy converter 10 is then carried out about 1 time out of 10 with a measured value of the elementary input DC voltage VPVi and therefore about 9 times out of 10 with the estimated value j of the elementary input DC voltage VPVi, calculated by the first estimator 80.

[0227] Thus, the control device 15 according to the invention makes it possible to operate the conversion system 5 at the operating frequency fB higher than the refresh rate fD without reducing the stability and accuracy of the regulation of the quantities VPVi and IG.

[0228] The results obtained with the control device 15 according to the invention are then illustrated in figures 6 to 8.

[0229] Figure 6 shows the actual instantaneous voltage of the photovoltaic unit 20 via curve 200 (solid line). This is a DC voltage with an average value of 13.2 V and a continuous natural ripple of 100 Hz (4% ripple). Curve 210 (dotted line) represents the estimated voltage Vpy calculated by the first estimator 80. Curve 220 (dashed line) represents the voltage retrieved by the main controller 50 via the communication bus 52. This update occurs at the refresh rate fD, and between updates, due to a lack of information, the voltage is assumed to be constant. This curve 220 clearly shows the lack of information available to the main controller 50 to perform its regulation algorithm. The waveform of curve 210 therefore reflects the actual voltage according to curve 200 much better than curve 220. This greatly improves the voltage regulation of photovoltaic blocks 20.

[0230] Figure 7 shows the evolution of the current of a conversion module 35 at startup (solid line curve 250), as well as the average current value constructed using the second estimator 85 (dashed line curve 260). In other words, curve 250 corresponds to the actual value of the elementary input current IPVi, and curve 260 corresponds to the estimated average of the elementary input current IPVi. Figure 7 thus demonstrates the ability of the second estimator 85 to quickly retrieve the information (with a network delay period) and to stabilize in steady state. This information, obtained simply by calculation and without measurement, can therefore be used to calculate the estimated value of the elementary input DC voltage VPVi via the first estimator 80.

[0231] Figure 8 shows, in solid line, a curve 300 representing the actual voltage of a photovoltaic block 20 over one grid period. Here, the actual value of the capacitance CPVi of capacitor 64 is 20% lower than the value taken into account in equation (1). In the dashed line, in the upper part of figure 8, a curve 310 represents the estimated value (fk) of the elementary DC input voltage VPVi using a predefined value of the capacitance CPVi of capacitor 64, such as the value supplied by the manufacturer of said capacitor 64, i.e. without taking into account the estimated value Cpy of the capacitance CPVi of capacitor 64 calculated by the third estimator 90. Curve 310 then shows some errors in estimating the voltage of the elementary DC input voltage VPVi compared to curve 300 representing the actual voltage. In the dashed line in the lower part of Figure 8, curve 320 represents the estimated value Vpv(L) of the elementary DC input voltage VPVi using the estimated value Cpv of the capacitance CPVi of capacitor 64 calculated by the third estimator 90. Curve 320, obtained using both the first estimator 80 and the third estimator 90, is therefore much closer to curve 300, representing the actual voltage, than was curve 310, obtained without implementing the third estimator 90.

[0232] The person skilled in the art will then observe that the third estimator 90 makes it possible to further improve the estimation of the elementary DC input voltage VPVi, by reducing the estimation errors, as can be seen from the comparison of curves 310 and 320.

[0233] According to a complementary aspect, Figures 9 and 10 illustrate the case where the loop frequency fB is different from the switching frequency fsw of the switches 38 of the conversion module 35.

[0234] The calculations of the control loop are performed by the control unit REG at the loop frequency fB. This control loop sends, at each control period Tb, with Tb = 1 / fB, state change commands to at most half of the conversion modules 35, or to a maximum of six conversion modules 35 if the number of conversion modules 35 is less than 12, so as to limit the number of switching operations (to limit losses) and to limit the number of commands to be sent (so as not to saturate the communication bus 52).

[0235] Advantageously, the number of conversion modules 35 that receive a state change order at each TB regulation period is less than a quarter of the conversion modules 35, or less than 4 conversion modules 35.

[0236] In an optimal case, only two maximum 35 conversion modules receive a state change order at each TB regulation period. This is the case described below.

[0237] At each TB regulation period, either no command is sent (maintaining the previous state), or a single command is sent to a single conversion module 35, or two commands are sent to two different conversion modules 35; for example:

[0238] - a connection command for module i (a single command)

[0239] - a disconnection command for module j (a single command)

[0240] - a connection command for module i and a disconnection command j (two commands)

[0241] The central controller 50 knows, in real time, the connection state of each conversion module 35. It can therefore only send a connection order to a conversion module 35 that is disconnected, and a disconnection order to a conversion module 35 that is connected.

[0242] For module i to execute a command, the central controller 50 sends KM data such that:

[0243] [Math.6]

[0244] Fig. 9 then illustrates the case of a disconnection command, and curve 400 represents the elementary output voltage VHi, i.e. the output voltage of the switching bridge 58, when this disconnection command is executed.

[0245] When Km^ — 0, module i directly puts the switching bridge 58 into bypass mode:

[0246] [Math.7] &i Gf) + Tloop} " 0

[0247] The output voltage 0 of the conversion module 35 over the period [f0 -* + Tg] is therefore:

[0248] [Math. 8] + =VPViTB) =0

[0249] Once the regulation period -» îq + TB] is over, module i waits to receive a new order from the central controller 50 to change state again (this can last one to several TB regulation periods).

[0250] On [Fig.9], the sequence of a disconnection command is then as follows.

[0251] For t <to, le module de conversion 35 est connecté :

[0252] [Math.9] y- ypv;

[0253] At t — ?q, module i receives the command Km = 0. Conversion module 35 immediately switches to bypass mode:

[0254] [Math. 10] y = y = o

[0255] At t = if the conversion module 35 receives a new order Km,, it executes it. Otherwise, it maintains its current state until a new order arrives:

[0256] [Math. 11] VHj(h^ ) =0

[0257] Fig. 10 then illustrates the case of a connection order, and curve 410 represents the elementary output voltage VHi, i.e. the output voltage of the switching bridge 58, when this connection order is executed.

[0258] When Km^o) 0' Ie module j will switch the switching bridge 58 at the switching frequency fsw (an integer multiple of the loop frequency fB) in order to obtain:

[0259] [Math. 12] kmM = 7" Jfo Kj(t).dt

[0260] When Km h>) > 0, the switching of the switching bridge 58 of module j at the switching frequency fsw complies with:

[0261] [Math. 13] Kj(to^to + TB)^O

[0262] The output voltage of the conversion module 35 over the period [f0 + Tg] is SO :

[0263] [Math. 14] VHr(t0 - tQ+TB) = Vp^t^K^ - tQ + TB) > 0

[0264] When Km}( ?q) < 0' 'a switching of the switching bridge 58 of module j at the switching frequency fsw respects:

[0265] [Math. 15] Kj(to^tQ+TB)ïO

[0266] The output voltage of the conversion module 35 over the period [0 + Tg] is SO :

[0267] [Math. 16] VMr^tn + Ts) = <0

[0268] On [Fig. 10], the sequence of a connection order is then as follows.

[0269] For t <t0, le module de conversion 35 est déconnecté :

[0270] [Math. 17]

[0271] At f — fo, module i receives the command Km. — + 0.5. The conversion module 35 will then switch during the period [ / 0 + TB] at the switching frequency fsw (here fsw = 4* fB) with a duty cycle of 0.5, in order to meet the condition:

[0272] [Math. 18] rL+T' b KMi ( ) = 0.5 = J r(i Kt ( t ) â t

[0273] At t = t}, if the conversion module 35 receives a new order, it executes it. Otherwise, it maintains its current state until a new order arrives: ^) = Vpvt-

[0274] The final state is a static state, that is, a configuration that is maintained (also applicable to the case of series / parallel switchable 35 conversion modules as in the example in Figure 3). This configuration is maintained until a new command is received. This final configuration (at t1+) is different from the initial configuration (at t0-). In a static configuration, which gives a value of K close to the static values ​​of K for the initial and final configurations, the value typically brackets the value.

[0275] Thus, only the conversion modules 35 receiving a command, here a maximum of two conversion modules 35, can exhibit switching at the switching frequency fsw, for a duration TB, all other conversion modules 35 remaining in the static state. Of course, a conversion module 35 can receive several commands in succession, and switch over several periods TB, but there will nevertheless be at most two conversion modules 35 exhibiting switching at the switching frequency fsw at the same time.

[0276] For a connection order such that Km < 0, the reasoning is analogous, except that when the conversion module 35 switches (K fa) 0) the voltage is negative: VH.(t) = -VPVfa)-

[0277] The switching frequency fsw is an integer multiple of the loop frequency fB, the multiple being greater than or equal to 1. Increasing the switching frequency fsw allows for a reduction in the size of the passive components of the output filter 16. Furthermore, increasing the loop frequency fB improves the accuracy (limiting tracking error, overshoot, oscillations, etc.) of the regulation of the system parameters: the elementary DC input voltages VPVi and the output current Is, corresponding to the mains current IG. Thus, it is still preferable to maintain a loop frequency fB much greater than the mains frequency fG 6 (at least >10 times), for example, with a loop frequency fB on the order of 20 kHz.

[0278] Fig. 11 then illustrates the case where the loop frequency fB is substantially equal to the switching frequency fsw of the switches 38 of the conversion module 35. Curve 450 represents the evolution of the connection coefficient K as a function of time t.

[0279] Even if the switching frequency fsw is substantially equal to the loop frequency fB, it is possible to apply a Km^q) different from a static state.

[0280] In the example in Figure 3 with series / parallel configurations, taking for example an initial K equal to +1 / 2 (initial configuration “Parallel+Positive Polarity”), a final K equal to +1 (final configuration “Series+Positive Polarity”) and an A equal to 0.85, the conversion module 35 must therefore go from the initial state to the final state during the period TB which goes from t0 to tl, to obtain the desired j during this period, the instant of transition from the initial state to the final state is determined such that the average value of K over this period is g j.

[0281] The principle is therefore similar to the case where the switching frequency fsw is greater than the loop frequency fB. A transition occurs from an initial static state ESini to a final static state ESf, different from the initial static state ESini, while ensuring a certain average value of the connection coefficient K over this transition period TB. Finally, the final state is maintained as long as the conversion module 35 does not receive a new command.

[0282] Thus, by limiting the number of conversion modules 35 receiving an order at each period TB, the number of switching operations is limited, and consequently also the quantity of orders to be sent on the communication bus 52.

[0283] In the examples in Figures 1 to 8, the loop frequency fB and the switching frequency fsw of the switches 38 are preferably assumed to be similar, i.e. of substantially equal values, such as of the order of 20 kHz.

[0284] Finally, [Fig. 12] shows the experimental results obtained using a prototype comprising six conversion modules 35 and operating at 20 kHz. Each conversion module 35 is connected to a 50 W photovoltaic unit 20 (such as a solar panel), and the total output power is 300 W. The converter 10 is connected to the electrical network 6, the voltage of which is stepped down (using an autotransformer, not shown) to a value of approximately 90 V. In [Fig. 12], curve 500 corresponds to the voltage VG of the electrical network 6, curve 510 corresponds to the current IG of the electrical network 6, and curve 520 corresponds to the voltage Vs at the output of the converter 10.

[0285] Curves 500, 510, and 520 are given in steady state. Figure 12 shows that the converter 10 perfectly manages to produce a sinusoidal output current IG, in phase with the voltage VG of the electrical network 6, with very good regulation dynamics (low Total Harmonic Distortion and unity power factor), and this with an operating frequency of 20 kHz, while stabilizing each conversion module 35 around its maximum power point. The oscillations in the output current IG and in the voltages of the photovoltaic blocks 20 correspond perfectly to those expected by the sizing calculations. passive elements. Thanks to the control device 15 according to the invention, the constraints of the communication bus 52 therefore have no impact on the operation of the conversion system 5.

[0286] It is thus understood that the control device 15 for the multilevel energy converter 10 according to the invention allows high frequency control, typically above 20kHz, of said converter 10 which can also be connected to a large number of energy sources 8, for example to more than ten energy sources 8, while limiting the data bus 52 throughput and reducing the complexity of the control device 15, as well as the size and volume of the output filtering elements, such as the filter 16.< / ipvi> < / ipvi> < / ipvi> < / ipy> < / ipvi> < / vpvi> < / ipvi> < / ipvi> < / ipvi> < / ipvi> < / vpvi> < / ipvi>

Claims

Demands

1. Electronic device (15) for controlling an electrical energy converter (10), the energy converter (10) being capable of delivering a total output voltage (Vs) and / or an output current (IG) from a plurality of DC input voltages (VPVi, VPV2, • VPVn), referred to as elementary DC input voltages (VPVi, VPV2, • VPVn), each originating from a respective energy source (8); the energy converter (10) comprising several energy conversion modules (35), each being capable of receiving at input an elementary DC input voltage (VPVi) from a respective energy source (8) and of delivering at output an elementary output voltage (VHi); the conversion modules (35) being connected in series by their outputs and the total output voltage (Vs) being equal to the sum of the elementary output voltages (VHi, VH2, • VHn);each conversion module (35) comprising several switches (38) for converting the respective elementary DC input voltage (VPVi) into the respective elementary output voltage (VHi), the electronic control device (15) comprising several elementary controllers (40) and a master controller (50) connected to each of the elementary controllers (40), each elementary controller (40) being associated with a respective conversion module (35) and configured to control the switches (38) of said conversion module (35), the master controller (50) being configured to perform regulation of an output quantity (Vs;Is) of the energy converter (10) by sending control commands to the elementary controllers (40), the regulation being carried out according to sets of elementary quantity(ies), each set of elementary quantity(ies) being associated with a respective conversion module (35), each elementary controller (40) being configured to regularly measure values ​​of the set of elementary quantity(ies) for the respective conversion module (35) to which it is associated, and then to transmit them to the main controller (50), the set of elementary quantity(ies) comprising the elementary DC input voltage (VPVi), characterized in that the main controller (50) comprises a first estimator (80) configured to calculate, for each conversion module (35), an estimated value t )) of the DC voltage; elementary input (VPVi) from a previously measured value (Vpvi(tk.p)) of the elementary DC input voltage (VPVi), and in that the main controller (50) further comprises a second estimator (85) configured to calculate, for each conversion module (35), an estimated average ( <ipvi>) of the elementary input current (IPVi) received by the conversion module (35), the estimated average ( <ipvi>) of the elementary input current (IPVi) is then used to calculate the estimated value jj of the elementary DC input voltage (VPVi).

2. Device (15) according to claim 1, wherein each conversion module (35) comprises two input terminals (54), two output terminals (56), a switching bridge (58) with several switching branches (60), each connected between the two input terminals (54) and comprising several switches (38) connected in series and connected together with a midpoint (62) connected to a corresponding output terminal (56), each conversion module (35) further comprising a capacitor (64) connected between the input terminals (54), in parallel with the switching bridge (58).

3. Device (15) according to claim 2, wherein the first estimator (80) is configured to calculate, for each conversion module (35), the estimated value ( ^ )) of the elementary input DC voltage (VPVi) as a function of the previously measured value (VPVi(tk-P)) of the elementary input DC voltage (VPVi), the capacitance (CPVi) of the capacitor (64) and a value of the current (ICi) flowing through said capacitor (64); the value of the current (ICi) flowing through said capacitor (64) preferably being obtained by the difference between a value of an elementary input current (IPVi) received by the conversion module (35) and a value of a bridge current (IHi) received by the switching bridge (58).

4. Device (15) according to claim 3, wherein the first estimator (80) is configured to calculate, for each conversion module (35), the estimated value )) of the elementary DC input voltage (VPVi) according to the following equation: VpyUk) ~ ^pv^kx) + (hv^tk) )-c" where y^ ( ) represents the estimated value of the elementary DC input voltage (VPVi), Vpvi(tk-i) represents a previous value of the elementary DC input voltage (VPVi), Ipvi(tk) represents the value of the elementary input current (IPVi), tk, and respectively tk_b represent respectively current and previous time instants, CPvi represents the capacitance of the capacitor (64), IHi_M (tk) represents the average value of the bridge current (IHi) between the time instants tk_i and tk; the previous value VPVi (tk_i) of the elementary DC input voltage (VPVi) being the previously measured value (VPVi(tk.p)) of the elementary DC input voltage (VPVi) if it was measured for the previous time instant, or the previous estimated value ( ti ) ) of the elementary DC input voltage (VPVi) if said previously measured value (VPVi(tk-p)) was measured for a time instant (tk p) prior to the previous time instant (tk_i); said average value IHi_M(tk) of the bridge current (IHi) preferably satisfying the following equation:

5. Device (15) according to any one of the preceding claims, wherein the second estimator (85) is configured to calculate, for each conversion module (35), the estimated mean ( <ipvi>) of the elementary input current (IPVi) over a period of averaged, as a function of the total output voltage (Vs) and an output current (Is) delivered at the output of the power converter (10), and an average value ( <vpvi>) of the elementary DC input voltage (VPVi) over the averaged time (Tg); the average duration (Tg) preferably depends on half a period of the output voltage (Vs).

6. Device (15) according to claim 5, wherein the second estimator (85) is configured to calculate, for each conversion module (35), the estimated mean ( <ipvi>) of the elementary input current (IPVi) according to the following equation: T _ i L' vy(OO(OlA3(O^ " Tg- <vpv> où <ipvi>represents the estimated average of the elementary input current (Ipvi)> Tg represents the average duration, Vs represents the total output voltage, Is represents the output current. <vpvi>represents the average value of the elementary DC input voltage (VPVi) over said averaging time (Tg), and K; represents a connection coefficient, K; being equal to 0 when no power source (8) is connected to the input of the corresponding conversion module (35) and different from 0 when at least one power source (8) is connected to the input of said module (35); the averaging time (Tg) preferably being a multiple of the half-period of the output voltage (Vs), said multiple being an integer greater than or equal to 1.

7. Device (15) according to any one of the preceding claims, taken with claim 2, wherein the main controller (50) further comprises a third estimator (90) configured to calculate, for each conversion module (35), an estimated value j of the capacitance (CPVi) of the capacitor (64).

8. Device (15) according to claim 7, wherein the third estimator (90) is configured to estimate a current value of the capacitance (CPVi) of the capacitor (64) by correcting a previous estimated value of the capacitance (CPVi) of the capacitor (64) based on, on the one hand, the sign of the difference between a value of a bridge current (IHi) received by the switching bridge (58) and a value of an elementary input current (IPVi) received by the conversion module (35), referred to as the first sign, and on the other hand, the sign of the difference between the estimated value ) j of the elementary DC input voltage (VPVi) and the subsequently measured value (VPVi(tk+i)) of the elementary DC input voltage (VPVi), referred to as the second sign; an initial estimated value of the capacitance (CPVi) of the capacitor (64) being predefined;if the first and second signs are identical, the current estimated value of the capacitance (CPVi) of the capacitor (64) is preferably equal to the previous estimated value of the capacitance (CPVi) of the capacitor (64) less one correction step (ACPVi); if the first and second signs are distinct, the current estimated value of the capacitance (CPVi) of the capacitor (64) is preferably equal to the previous estimated value of the capacitance (CPVi) of the capacitor (64) plus the correction step (ACPVi); the correction step (ACPVi) being preferably on the order of percent; of the initial value of the capacitance (CPVi) of the capacitor (64).

9. Device (15) according to any one of the preceding claims, wherein each energy source (8) comprises at least one element selected from: a photovoltaic block (20), an electric battery and a supercapacitor.

10. Device (15) according to claim 9, wherein each energy source (8) comprises P pair(s) of photovoltaic blocks (20), the photovoltaic blocks (20) of a respective pair being cascaded, P being an integer greater than or equal to 1; if P is strictly greater than 1, the pairs of photovoltaic blocks (20) preferably being cascaded.

11. Device (15) according to claims 2, 6 and 9, wherein each conversion module (35) comprises Q capacitors, where Q, equal to twice the number P, represents the number of photovoltaic blocks (20) for the energy source (8) associated with the conversion module (35), each capacitor (64) being suitable for being connected in parallel with a respective photovoltaic block (20), the Q capacitors (64) having substantially identical capacitance, and wherein when the connection coefficient (K) is non-zero, its value is a multiple of 1 / Q, the multiple being a relative integer whose value depends on a connection configuration of the photovoltaic blocks (20) and a connection state of each of the photovoltaic blocks (20), each connection state being among connected and disconnected.

12. An electronic electrical energy conversion system (5) capable of converting a plurality of DC input voltages (VPVi, VPV2, ..., VPVn) into a total output voltage (Vs) and / or an output current (IG), the conversion system (5) comprising: - an energy converter (10) capable of delivering the total output voltage (Vs) and / or the output current (IG) from the plurality of DC input voltages (VPVi, VPV2, ..., VPVn), referred to as elementary DC input voltages (VPVi, VPV2, ..., VPVn), each originating from a respective energy source (8); the energy converter (10) comprising several energy conversion modules (35), each capable of receiving at its input an elementary DC input voltage (VPVi) from a respective energy source (8) and delivering at its output an elementary output voltage (VHi); the conversion modules (35) being connected in series by their outputs and the voltage total output (Vs) being equal to the sum of the elementary output voltages (VPVi, VPV2, • VPVn); each conversion module (35) comprising several switches (38) to convert the respective elementary DC input voltage (VPVi) into the respective elementary output voltage (VHi), - an electronic device (15) for controlling the electrical energy converter (10), characterized in that the electronic control device (15) is according to any one of the preceding claims.

13. Method for controlling an electrical energy converter (10), the energy converter (10) being capable of delivering a total output voltage (Vs) and / or an output current (IG) from the plurality of DC input voltages (VPVi, VPV2, VPVnX), referred to as elementary DC input voltages (VPVi, VPV2, VPVn), each originating from a respective energy source (8); the energy converter (10) comprising several energy conversion modules (35), each being capable of receiving at its input an elementary DC input voltage (VPVi) from a respective energy source (8) and of delivering at its output an elementary output voltage (VHi); the conversion modules (35) being connected in series by their outputs and the total output voltage (Vs) being equal to the sum of the elementary output voltages (VPVi, VPV2, VPVn);each conversion module (35) having several switches (38) to convert the respective elementary DC input voltage (VPVi) into the respective elementary output voltage (VHi), the control method being implemented by a main controller (50) connected to each of several elementary controllers (40), each elementary controller (40) being associated with a respective conversion module (35) and configured to control the switches (38) of said conversion module (35), the method comprising: - performing regulation of an output quantity (Vs;Is) of the energy converter (10) by sending control commands to the elementary controllers (40), the regulation being carried out according to sets of elementary quantity(ies), each set of elementary quantity(ies) being associated with a respective conversion module (35), each elementary controller (40) regularly measuring values ​​of the set of elementary quantity(ies) for the respective conversion module (35) to which it is associated, and then transmitting them; to the main controller (50), the set of elementary quantity(ies) comprising the elementary DC input voltage (VPVi), characterized in that it further comprises: - calculate, for each conversion module (35), an estimated value (Vpv ( 4 )) of the elementary DC input voltage (VPVi) from a previously measured value (VPVi(tk-p)) of the elementary DC input voltage (VPVi), and - calculate, for each conversion module (35), an estimated average ( <ipvi>) of the elementary input current (IPVi) received by the conversion module (35), the estimated average ( <ipvi>) of the elementary input current (IPVi) is then used to calculate the estimated value of the elementary input DC voltage (VPVi).

14. A computer program comprising software instructions which, when executed by a computer, implement a method according to the preceding claim.< / ipvi> < / ipvi> < / vpvi> < / ipvi> < / vpv> < / ipvi> < / vpvi> < / ipvi> < / ipvi> < / ipvi>

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