Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
  • H02M3/00—Conversion of DC power input into DC power output
  • H02M3/22—Conversion of DC power input into DC power output with intermediate conversion into AC
  • H02M3/24—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters
  • H02M3/28—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC
  • H02M3/325—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal
  • H02M3/335—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
  • H02M3/33569—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
  • H02M3/33576—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
  • H02M3/33584—Bidirectional converters
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
  • H02M3/00—Conversion of DC power input into DC power output
  • H02M3/22—Conversion of DC power input into DC power output with intermediate conversion into AC
  • H02M3/24—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters
  • H02M3/28—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC
  • H02M3/325—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal
  • H02M3/335—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B64—AIRCRAFT; AVIATION; COSMONAUTICS
  • B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
  • B64D27/00—Arrangement or mounting of power plants in aircraft; Aircraft characterised by the type or position of power plants
  • B64D27/02—Aircraft characterised by the type or position of power plants
  • B64D27/026—Aircraft characterised by the type or position of power plants comprising different types of power plants, e.g. combination of a piston engine and a gas-turbine
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B64—AIRCRAFT; AVIATION; COSMONAUTICS
  • B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
  • B64D27/00—Arrangement or mounting of power plants in aircraft; Aircraft characterised by the type or position of power plants
  • B64D27/02—Aircraft characterised by the type or position of power plants
  • B64D27/24—Aircraft characterised by the type or position of power plants using steam or spring force
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B64—AIRCRAFT; AVIATION; COSMONAUTICS
  • B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
  • B64D27/00—Arrangement or mounting of power plants in aircraft; Aircraft characterised by the type or position of power plants
  • B64D27/02—Aircraft characterised by the type or position of power plants
  • B64D27/30—Aircraft characterised by electric power plants
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B64—AIRCRAFT; AVIATION; COSMONAUTICS
  • B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
  • B64D27/00—Arrangement or mounting of power plants in aircraft; Aircraft characterised by the type or position of power plants
  • B64D27/02—Aircraft characterised by the type or position of power plants
  • B64D27/30—Aircraft characterised by electric power plants
  • B64D27/35—Arrangements for on-board electric energy production, distribution, recovery or storage
  • B64D27/357—Arrangements for on-board electric energy production, distribution, recovery or storage using batteries
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B64—AIRCRAFT; AVIATION; COSMONAUTICS
  • B64U—UNMANNED AERIAL VEHICLES [UAV]; EQUIPMENT THEREFOR
  • B64U50/00—Propulsion; Power supply
  • B64U50/10—Propulsion
  • B64U50/19—Propulsion using electrically powered motors
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J7/00—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries
  • H02J7/855—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries with circuits adapted for supplying loads from the battery
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
  • H02M1/00—Details of apparatus for conversion
  • H02M1/0067—Converter structures employing plural converter units, other than for parallel operation of the units on a single load
  • H02M1/007—Plural converter units in cascade
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
  • H02M3/00—Conversion of DC power input into DC power output
  • H02M3/22—Conversion of DC power input into DC power output with intermediate conversion into AC
  • H02M3/24—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters
  • H02M3/28—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC
  • H02M3/325—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal
  • H02M3/335—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
  • H02M3/33569—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
  • H02M3/33573—Full-bridge at primary side of an isolation transformer
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
  • H02M7/00—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output
  • H02M7/02—Conversion of AC power input into DC power output without possibility of reversal
  • H02M7/04—Conversion of AC power input into DC power output without possibility of reversal by static converters
  • H02M7/12—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
  • H02M7/21—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
  • H02M7/217—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
  • H02M7/219—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only in a bridge configuration
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B64—AIRCRAFT; AVIATION; COSMONAUTICS
  • B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
  • B64D2221/00—Electric power distribution systems onboard aircraft
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B64—AIRCRAFT; AVIATION; COSMONAUTICS
  • B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
  • B64D27/00—Arrangement or mounting of power plants in aircraft; Aircraft characterised by the type or position of power plants
  • B64D27/02—Aircraft characterised by the type or position of power plants
  • B64D27/30—Aircraft characterised by electric power plants
  • B64D27/33—Hybrid electric aircraft
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J2105/00—Networks for supplying or distributing electric power characterised by their spatial reach or by the load
  • H02J2105/30—Networks for supplying or distributing electric power characterised by their spatial reach or by the load the load networks being external to vehicles, i.e. exchanging power with vehicles
  • H02J2105/32—Networks for supplying or distributing electric power characterised by their spatial reach or by the load the load networks being external to vehicles, i.e. exchanging power with vehicles for aircrafts
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J2207/00—Details of circuit arrangements for charging or discharging batteries or supplying loads from batteries
  • H02J2207/20—Charging or discharging characterised by the power electronics converter

Definitions

• the invention relates to the field of aircraft propulsion electrical networks and relates, in particular, to a DC/DC converter for such a network.
• a hybrid propulsion architecture 101 generally comprises:
• a rectifier 109 connected to the electric generator 107 and configured to convert an alternating current (in this case a three-phase current) delivered by the electric generator 107 into a direct current
• DC high voltage bus 111 connecting the rectifier 109 to the DC/AC converters 113a and 113b, - electric motors 115a and 115b connected to the DC/AC converters 113a and 113b so that in operation the DC/AC converters 113a and 113b supply the electric motors 115a and 115b with alternating current, and
• Architecture 101 also includes an electrical energy storage unit 119 (also called “HVDC storage” meaning high voltage direct current storage), such as, for example, a battery.
• This electrical storage unit performs the following functions: absorb excess electrical energy from the HVDC bus, provide additional electrical energy supply during transient phases, or serve as the main energy source with the motor thermal or as a replacement for this thermal engine, in the event of failure for example.
• the storage unit 119 absorbs this excess electrical energy in order to protect the components of the HVDC bus.
• the internal combustion engine 103 from a source of fossil fuel, the internal combustion engine 103, the electric generator 107 and an electric propulsion chain composed of DC/AC converters 113a and 113b, electric motors 115a and 115b and propellers 117a and 117b make it possible to fly an aircraft with multi-rotary wings.
• An aircraft comprising such a hybrid propulsion architecture is multi-rotor, which makes it possible to have additional degrees of freedom, compared to conventional aircraft, with regard to the controllability of the aircraft, for example, braking, strategy avoidance, change of direction, or tilting of the rotors.
• such an architecture can be used for an aircraft of the VTOL type (from the English “Vertical take-off and Landing”) or for an aircraft of the CTOL type (from the English “Conventional Take-Off and Landing”). ").
• this electrical energy storage unit may or may not be associated with a DC/DC converter whose role is in particular to adapt the voltage level and the current level delivered by the storage unit.
• the electrical energy storage unit is connected to the rest of the propulsion electrical network without using a DC/DC converter.
• a direct connection We are talking about a direct connection.
• the direct connection of one or more batteries makes it possible to minimize the mass of the complete electrical network. Indeed, the addition of a DC/DC converter has a cost in terms of mass but also in terms of volume, efficiency, heat dissipation and complexity of control.
• the network voltage level impacts the state of charge of the battery(ies). As this varies, the electrical quantities of the batteries vary accordingly.
• a second approach is that which consists in using a DC/DC converter at the interface between the electrical energy storage unit and the rest of the propulsion electrical network.
• the addition of such a DC/DC converter has multiple advantages.
• the voltage of the electrical energy storage unit is decoupled from that of the rest of the propulsion electrical network, which makes it possible to maintain a different voltage level between the energy storage unit and that of the HVDC bus.
• the DC/DC converter can be step-up and/or step-down, i.e. it can make it possible to increase or decrease the voltage at its output compared to that which the storage unit electrical energy supplied to it as input.
• the DC/DC converter when the DC/DC converter is of the current reversible type, it is also possible to control the energy level, also called state of charge (corresponding to the English acronym SOC for "State of Charge”) of the unit energy storage.
• Such a DC/DC converter at the interface between the electrical energy storage unit and the rest of the propulsion electrical network also makes it possible to add, if necessary, a galvanic insulation property (i.e. say the absence of a conductive connection between two parts of the electrical network).
• the DC/DC converter then has a structure called in complete bridges, for example a structure in controlled complete bridges known under the name DAB, which is the acronym of "Dual Active Bridge".
• DC/DC converters are sized to transmit the total power of the electrical energy storage unit, which necessarily involves a large mass of passive components and current/voltage ratings (i.e. capacities at pass high currents/voltages) depending on the case of use. Moreover, the yields of such systems rarely exceed 90%.
• the present invention proposes a solution to these drawbacks.
• the invention relates to a DC/DC converter for an aircraft propulsion electrical network intended to be connected in series with an electrical energy storage unit of said propulsion electrical network, said DC/DC converter DC comprising an inverter configured to supply a first alternating voltage from an input direct voltage coming from the electrical energy storage unit, a transformer configured to supply at least a second alternating voltage from the first voltage alternating current and a rectifier configured to provide an output direct voltage from the at least one second alternating voltage, said DC/DC converter being characterized in that it further comprises a current source, connected to the rectifier and configured to controlling the power passing through said DC/DC converter, in that the transformer comprises a primary and two secondaries, the two secondaries having a common terminal intended to be connected to a high voltage direct current (HVDC) bus of the propulsion electrical network and two other terminals connected to the rectifier, the reference levels of the DC/DC converter and the HVDC bus being connected to each other via the current source, and in that the rectifier comprises two arms, each comprising
• the DC/DC converter according to the invention may comprise one or more of the following characteristics, taken separately from each other or in combination with each other:
• the current source comprises an inductance and an electrical energy storage unit.
• the inverter comprises a plurality of transistors, preferably four transistors of the MOSFET type or of the IGBT type.
• the transistors have a switching frequency greater than a few tens of kHz, advantageously of the order or greater than a hundred kHz.
• the transformer is configured to lower the at least one second alternating voltage with respect to the first alternating voltage.
• the transformer is planar type or wound type.
• the transformer is configured to provide galvanic isolation between the primary and the two secondaries of said transformer.
• the rectifier comprises four transistors with two transistors connected in series to each secondary of the transformer, said transistors being of the MOSFET type.
• - diodes connected in parallel to the transistors, are configured to protect said transistors from overvoltages.
• At least one filter preferably of the RC filter type, is connected between the transformer and the rectifier.
• a filter preferably of the RC filter type, is connected to the terminals of each arm of the rectifier, in parallel with the transistors.
• the invention also relates, according to a second aspect, to an aircraft propulsion electrical network comprising at least one thermoelectric source and one electrical energy storage configured to supply electrical energy to a DC high voltage bus intended to supply loads, said aircraft propulsion electrical network further comprising a DC/DC converter according to the first aspect.
• the propulsion electrical network according to the invention may comprise one or more of the following characteristics, taken separately from each other or in combination with each other:
• the electrical energy storage unit is an electrolytic current source, such as for example a supercapacitor, or an electrochemical current source, such as for example a battery.
• the propulsion electrical network further comprises a contactor configured to directly connect, when activated, a high potential of the high voltage DC bus with a high potential of the electrical energy storage unit.
• FIG. 1 is a schematic representation of an embodiment of a hybrid propulsion architecture of an aircraft according to the prior art
• FIG. 2 is a schematic representation of an embodiment of an aircraft propulsion electrical network according to the invention
• FIG. 3 is a schematic representation of an embodiment of an aircraft propulsion electrical network according to the invention
• FIG. 4 is a schematic representation of an embodiment of a DC/DC converter of an aircraft propulsion electrical network according to the invention
• FIG. 5 is a schematic representation of an embodiment of a DC/DC converter of an aircraft propulsion electrical network according to the invention
• FIG. 1 is a schematic representation of an embodiment of a hybrid propulsion architecture of an aircraft according to the prior art
• FIG. 2 is a schematic representation of an embodiment of an aircraft propulsion electrical network according to the invention
• FIG. 3 is a schematic representation of an embodiment of an aircraft propulsion electrical network according to the invention
• FIG. 4 is a schematic representation of an embodiment of a DC/DC converter of an aircraft propulsion electrical network according to the invention
• FIG. 5 is a schematic representation of
• FIG. 6 is a schematic representation of an embodiment of a DC/DC converter of an aircraft propulsion electrical network according to the invention
• FIG. 7 is a schematic representation of an embodiment of a DC/DC converter of an aircraft propulsion electrical network according to the invention
• FIG. 8 is a schematic representation of an embodiment of a DC/DC converter of an aircraft propulsion electrical network according to the invention
• FIG. 9 is a schematic representation of an embodiment of a DC/DC converter of an aircraft propulsion electrical network according to the invention
• FIG. 10 is an example of a control sequence for transistors of an inverter of a DC/DC converter according to the invention and of an alternating voltage generated by the inverter in response to this control sequence
• FIG. 11 is an example of voltages obtained at the terminals of the two arms of a rectifier of a DC/DC converter according to the invention from the voltage generated by the inverter in the example represented in FIG. 10.
• the propulsion electrical network 201 includes at least one thermoelectric source 203 and one electrical energy storage unit 205 which are configured to supply electrical energy to a high voltage direct current (HVDC) bus 207.
• HVDC high voltage direct current
• the thermoelectric source 203 comprises an internal combustion engine 203a, an electric generator 203b coupled to the internal combustion engine 203a and a rectifier 203c connected to the electric generator 203b.
• the thermoelectric source 203 supplies direct current to the HVDC bus 207.
• the HVDC bus 207 is intended to supply loads (not shown) such as, for example, electric motors of an aircraft.
• the aircraft concerned may be an aircraft of the VTOL type or of the CTOL type.
• the invention is particularly well suited to aircraft whose mass is less than 5 tons and which have an onboard mechanical power of between 50 and 2000 kW.
• the aircraft propulsion electrical network 201 also comprises a DC/DC converter 209 (for direct current/direct current), connected in series with the electrical energy storage unit 205, at the interface between the storage unit of electrical energy 205 (also called "HVDC storage”) and the HVDC bus 207.
• a DC/DC converter 209 for direct current/direct current
• HVDC storage also called "HVDC storage”
• the electrical energy storage unit 205 can be an electrolytic current source, such as for example a supercapacitor, or an electrochemical current source, such as for example a battery.
• the energy storage unit behaves, during different operating phases, as an energy source (i.e. in source mode) or as a load (i.e. in load mode).
• the invention also applies to an energy storage unit behaving solely as a non-reversible energy source such as a solar panel or even a battery.
• a source of the supercapacitor type has the characteristic of being capable of supplying power peaks, that is to say high power for a very short period of time.
• supercapacitors are very useful for responding in transient state to strong power demands which may be associated with a take-off phase of the aircraft. On the other hand, they are not adapted to a need for power over a long period of time.
• Supercapacitors are also capable of withstanding a very large number of charge/discharge cycles.
• a battery is not suitable for responding to power peaks. It is able to provide average power over a long period of time.
• a battery provides great energy autonomy. On the other hand, it supports a smaller number of charge/discharge cycles.
• the DC/DC converter 209 comprises an inductance 213 connected to the output of this assembly 215 on the one hand and to the positive terminal of the storage unit 205 on the other hand, to control the current between the storage unit 205 and the HVDC bus 207.
• the inductor 213 forms with the assembly 215 a so-called partial power converter (or PPC for the English “Partial Power Converter”) which makes it possible, depending on the use case, not to transfer all the power emitted by the storage unit 205 to the HVDC bus 207.
• PPC Partial Power Converter
• an inductance and an energy storage unit connected to each other carry out the function of controlling the current which passes between the storage unit 205 and the HVDC bus 207.
• this inductor allows, during a phase during which the storage unit 205 is charging, that the majority of the power transiting from the HVDC bus to the storage unit can pass through said inductor .
• the yield of the set is close to 1.
• the propulsion electrical network 201 can also comprise a contactor (not shown) configured to connect directly, when activated, a high potential of the HVDC bus 207 with a high potential of the electrical energy storage unit 205.
• this contactor makes it possible to directly connect the electrical energy storage unit 205 to the HVDC bus 207 so that a possible failure of the DC/DC converter 209 does not lead to the loss of the energy storage unit. electric 205 or the HVDC bus 207.
• DC/DC converter 209 for an aircraft propulsion electrical network.
• the DC/DC converter 209 described is intended to be connected in series with an electrical energy storage unit of a propulsion electrical network such as the electrical energy storage unit 205 of the electrical propulsion network 201 described with reference to Figure 3.
• the DC/DC converter 209 comprises an inverter 401 configured to supply an alternating voltage from a direct voltage called input voltage which is supplied by the electrical energy storage unit.
• the inverter 401 is a single-phase inverter, that is to say it receives an alternating electric current on a transmission line made up of two parallel wires, namely, respectively, a line which includes the transistors 413a and 413c and a line which includes transistors 413b and 413d.
• the inverter comprises four transistors 413a, 413b, 413c and 413d distributed over two rows of two transistors in series.
• the invention applies to an inverter comprising a number of transistors greater than two on each of the two lines.
• transistors of the MOSFET type from the English “Metal Oxide Semiconductor Field Effect Transistor” meaning metal-oxide gate field effect transistor
• IGBT type transistors from the English “Insulated Gate Bipolar Transistor” meaning insulated gate bipolar transistor
• the transistors of the inverter, 413a, 413b, 413c and 413d illustrated in FIG. 4, are made of a material making it possible to obtain a high switching frequency, such as SiC (silicon carbide) for example. or GaN (Gallium Nitride). In this way the size of the magnetic components (transformers and inductance) are advantageously smaller and the volume of the inverter is minimized.
• a high chopping frequency that is to say typically greater than a few tens of kHz, or even of the order or greater than a hundred kHz, makes it possible to increase the frequency of the signal cut (the current or the voltage at the output of the inverter and rectifier stages) and also to improve its control (current and voltage control).
• a switching frequency of up to 30 or 40 kHz can be used.
• transistors made of so-called wide-gap material such as SiC or GaN it is possible to go further. For example, it is possible to obtain chopping frequencies of the order of 100-200 kHz.
• the DC/DC converter 209 also includes a transformer 403 configured to generate at least one alternating voltage from the alternating voltage supplied at the output of the inverter 401.
• the transformer 403 is said to be step-down insofar as it is configured to generate a lower voltage at the output than at the input. Indeed, the voltage from the electrical energy storage unit used is much higher than the voltage necessary to guarantee control of the current flowing between the electrical energy storage unit and the HVDC bus, which constitutes a purpose of using the DC/DC converter as described later.
• step-up transformer it is possible to use a so-called step-up transformer, depending in particular on whether or not the reversible nature of the electrical energy storage unit used to which the DC/DC converter is connected.
• the electrical energy storage unit at a nominal voltage higher than the network voltage to allow ease in controlling the flow of power from the storage unit to the network.
• the source has a lower voltage and it is necessary to couple it with a step-up transformer to allow good transfer the power from the source to the network.
• the architecture is fixed and the type of transformer used is determined beforehand.
• the transformer can be of the planar type or of the wound type.
• the transformer 403 comprises a primary 403a and two secondaries 403b and 403c.
• the transformer can be configured to achieve galvanic isolation between the primary 403a and the two secondaries 403b and 403c.
• the two secondaries 403b and 403c have a common terminal 407 which is intended to be connected directly to the HVDC bus 207 and two other terminals 409 and 411 which are connected to the two arms of a rectifier 405 described below.
• the DC/DC converter 209 also comprises a rectifier 405 configured to supply a DC output voltage from one or more AC voltages coming from the transformer 403.
• the rectifier 405 is a so-called four-quadrant type rectifier.
• the rectifier 405 comprises four transistors 415a, 415b, 415c and 415d which can also be, for example, of the MOSFET type or of the IGBT type.
• the rectifier shown comprises two rows (two arms) of two transistors in series.
• the invention also applies to a rectifier comprising a higher number of transistors per line.
• the DC/DC converter 209 also comprises a current source 417, connected to the two arms of the rectifier 405 (for example, via a terminal common to these two arms), which consists, on the one hand, of an inductance and, on the other hand, either of the unit storage 205, or another storage unit.
• the current source consists of the inductance 213 and the storage unit 205.
• the reference levels ( and therefore the reference voltages) of the DC/DC converter 209 and the HVDC bus 207 are connected to each other via the current source (formed by the inductor 213 and the storage unit 205 ).
• the output of the two arms of the rectifier 405 is connected to the current source 417 which is connected to a reference level of the HVDC bus 207.
• this current source 417 which makes it possible to control the power which passes from the storage unit 205 to the HVDC bus 207.
• the use of the current source 417 makes it possible to impose a voltage at the output of the DC/DC converter which regulates the current flowing between the electrical storage unit and the HVDC bus and, if necessary, maintains a different voltage level between the electrical energy storage unit and the HVDC bus.
• the DC/DC converter 209 is therefore said to be at partial power due to its ability to transmit only part of the power supplied by the storage unit to which it is connected.
• the DC/DC converter makes it possible to control the state of charge of the electrical energy storage unit independently of the voltage of the HVDC bus and to control the transient current at the terminals of the energy storage unit. electric. This last point makes it possible to preserve the integrity of the electrical energy storage unit and to avoid thermal runaways liable to degrade it.
• the invention also applies to a propulsion electrical network which comprises several electrical energy storage units in parallel each having a DC/DC converter such as that described.
• such a DC/DC converter can be dimensioned for the operating range of the electrical energy storage unit, that is to say according to the current and voltage ratings. Also advantageously, the DC/DC converter makes it possible to equalize the voltage of the electrical energy storage unit and that of the HVDC bus while regulating the current circulating between the two.
• the propulsion electrical network can be reconfigured (ie an electrical energy storage unit can be added or removed) without damaging or straining an electrical energy storage unit already in use.
• FIGS. 4 to 9 show different embodiments of a DC/DC converter for an aircraft propulsion electrical network according to the invention. These figures notably illustrate in more detail several examples of architecture of the rectifier 405 of the DC/DC converter 209.
• transistors 415a and 415b of rectifier 405 are connected in series to secondary 403b and transistors 415c and 415d of rectifier 405 are connected in series to secondary 403c of transformer 403.
• the gates of the two transistors connected in series to each secondary are common.
• this configuration makes it possible to limit the number of signals required for controlling the rectifier.
• diodes 419 connected in parallel to transistors 415a, 415b, 415c and 415d are configured to protect transistors 415a, 415b, 415c and 415d from possible overvoltages. Furthermore, in the first case, the gates of the two transistors connected in series to each secondary are common and, in the second case, the gates of the two transistors connected in series to each secondary are distinct. Finally, in the examples shown in Figure 3, Figure 8 and Figure 9, one or more filters 421 are connected to terminals of the rectifier.
• one or more filters can be connected between the transformer and the rectifier or even between the two drains of two MOSFET type transistors on each arm of the rectifier, in parallel with the transistors.
• filters 421 make it possible to eliminate certain unwanted frequencies from the voltage which reaches the rectifier 405.
• the filters used are of the RC type, that is to say using the combination of a resistor and a a capacitor connected in series to filter certain frequencies.
• FIG. 10 and FIG. 11 show an example of a command applied to a DC/DC converter according to the invention and the voltage obtained at the output of the converter from such a command.
• FIG. 10 shows, in its left part, an example of a control sequence for the transistors of an inverter of a DC/DC converter such as that shown in FIG. 6.
• the control sequence corresponds to a sequence of voltages applied, as a function of time (on the abscissa) to the four transistors of the inverter.
• the voltages represented can be sent to terminals G (for gate) and S (for Source) of a MOSFET type transistor or G and E (for emitter) of an IGBT type transistor.
• each control voltage is a square signal passing from a zero value to a positive value (normalized to 1 in the example) and having the effect, respectively, that the transistor behaves like an open or closed switch.
• the right part of Figure 10 shows the voltage which results from this control sequence and which is applied to the primary of the transformer (called primary voltage) of the DC/DC converter.
• Figure 11 shows examples of voltages obtained at the terminals of the two arms of a rectifier of a DC/DC converter such as that described with reference to Figure 6 from the voltage generated by the inverter according to the example given in Figure 10.
• the top curve shows the primary voltage obtained from the control sequence applied to the inverter as described with reference to figure 10.
• the middle curve and the bottom curve show the voltages obtained at the terminals of the two arms of the DC/DC converter rectifier (which are respectively connected to the two secondaries of the converter transformer) from this primary voltage.
• the voltage K1 corresponds to the voltage obtained at the terminals of the line of two transistors in series 415a and 415b while the voltage K2 corresponds to the voltage obtained at the terminals of the line of two transistors in series 415c and 415d.

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• Engineering & Computer Science (AREA)
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• Aviation & Aerospace Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Dc-Dc Converters (AREA)
• Physics & Mathematics (AREA)
• Electromagnetism (AREA)

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• 2022
  • 2022-01-07 FR FR2200108A patent/FR3131812B1/fr active Active
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