JP5597876B2 - Electrical network - Google Patents

Description

  The present invention relates to electrical networks. The present invention finds particular utility in aeronautics for wide-body commercial aircraft with more on-board electrical equipment. Such devices vary greatly in nature and their energy consumption varies significantly over time. As an example, in-flight air conditioning and lighting systems work almost continuously, while redundant safety systems such as control of control wings are only used exceptionally.

  In general, an aircraft is equipped with a three-phase generator that allows power supply to all onboard electricity, hereinafter referred to as loads. These generators, for example, supply a voltage of 115 V to the aircraft AC bus at a frequency of 400 Hz. There are one or more main generators on board the aircraft. These are rotating electrical machines driven by aircraft engines. Well known in the literature, for example by the name “auxiliary power supply unit”, an auxiliary generator driven by a turbine dedicated to this generator, or a parking lot prepared and arranged for an aircraft when on the ground at many airports. Other generators, such as a field generator, can power the AC bus. This parking generator makes it possible to avoid asking for the help of an auxiliary generator when the aircraft is on the ground.

  In recent years, with the advent of high output loads (motors or AC sub-networks) that need to be powered by a three-phase voltage inverter, high voltage DC buses powered from AC buses through rectifiers have been installed on aircraft. . These high voltage DC buses are well known in the literature by the name of HVDC, which stands for “High Voltage Direct Current”. Hereinafter, the high voltage DC bus is referred to as an HVDC bus.

  The aircraft also includes a battery that allows a certain load to be supplied when AC power (parking generator or group thereof) is not available.

  In particular, the battery must support certain computers or certain critical electrical systems, such as steering gear, brakes, engine reverse thrust, or turbine start, through a low voltage DC bus.

  The battery is, for example, DC24V (or as an option in the future) to power the critical computer power supply as directly as possible, and to limit the number of batteries in series, the current standard is DC28V. Traditionally has a low voltage of DC48V).

  For higher power electrical loads, such as braking systems, reverse thrust, or engine starting, DC-DC so that low voltage batteries can be used whose voltage is much lower than the HVDC high voltage DC bus. A boost converter is used. It would also be possible to envisage the use of higher voltage special batteries for these loads so as to limit or cancel the required voltage rise between the battery and the HVDC bus.

  For example, a low voltage DC bus of DC 28V is typically made from an AC bus using a transformer and rectifier unit manufactured by many aircraft equipment manufacturers. This unit is well known in the literature under the name “Transformer Rectifier Unit” and is hereinafter referred to as “TRU”. The TRU is powered by the aircraft AC bus and supplies a 28V DC voltage. A TRU typically comprises a transformer that operates at a frequency of the aircraft AC network, for example between 300 Hz and 1200 Hz.

  The low voltage battery is then charged directly from the low voltage DC bus or through a battery charger that utilizes a DC-DC converter.

  Another solution for realizing the energy transfer link between the low voltage DC bus and the HVDC bus is a pulse width modulated bidirectional DC / DC dedicated converter using a high frequency transformer, or two each using a high frequency transformer. Independent head-to-tail DC-DC converters are used. High frequency is understood to mean frequencies above 10 kHz.

  This solution using a high frequency pulse width modulation converter with a high power level is significantly less reliable, more expensive and heavier than a conversion solution that typically uses a TRU powered by an AC network. .

  The TRU is not bidirectional, so the AC bus is powered from a low voltage DC bus with a generator or a dedicated three-phase inverter.

The object of the present invention is to simplify the execution of the conversion function by limiting the reliance on dedicated strategies for the following functions:
1. Power supply of the voltage X DC bus regulated from the voltage Y DC bus;
2. Battery charging at voltage X from the DC bus at voltage Y;
3. Power supply of the DC bus of voltage Y adjusted from the DC bus of voltage X or battery voltage X;
4). Battery charging at voltage Y from voltage X bus.
In the above conversion function, X is smaller than Y. Other conversion functions can of course be deduced from the means of the invention.

For this purpose, the subject of the present invention is:
・ Two devices that can supply or consume electrical energy,
A communication means connected between the two devices and enabling energy exchange between the two devices;
An electrical network, characterized in that the transmission means comprise a reversible DC / AC converter, which can be driven in step-down or step-up DC / DC mode.

  The first of the two devices forms a power supply bus, for example a first DC bus. One of the second devices forms a second DC bus, for example, which can be charged by the second bus or, if necessary, can be connected to a rechargeable battery.

  In certain embodiments, where two devices are formed with two DC buses whose voltages are different X and Y, the transmission means allows for one-way and opposite-direction electrical energy exchange between the buses. . One battery can be connected to each bus. The present invention makes it possible to control the exchange of energy from or to the battery. The transmission means allows adjustment of the voltage of one of the buses when the voltage is supplied from the other bus, or allows adjustment of the current flowing between the DC buses.

For this purpose, the transmission means is between two buses:
1. Its DC input is connected to the voltage Y bus, which is:
・ Step-down three-phase voltage inverter mode,
A parallel single-phase step-down DC / DC converter mode;
One or more reversible DC / AC multi-phase inverters that can operate in parallel or single phase boost DC / DC converter mode;
2. Optionally, a step-down TRU whose transformation ratio is connected to the AC output of the inverter and allows the voltage X to produce the voltage X;
3. Optionally, the DC input is connected to a bus of voltage X, which can operate in a step-down three-phase voltage inverter mode, and the voltage transformation ratio allows the voltage Y to be generated from the voltage X present at the input of the inverter. And a reversible DC / AC three-phase inverter with its AC output connected to the TRU.

  In certain embodiments in which the first device forms a power supply bus, such as an HVCD bus, the network allows energy exchange between several second devices and the bus and various second devices. A plurality of reversible converters and a switching means for enabling a change of the combination between the converter and the second device. Advantageously, all converters can exchange energy with each second device. The optional second device does not have any dedicated converter.

  In other words, the reversible DC / AC converter can be used to power various loads on the aircraft from the aircraft power supply bus. Several converters can be shared through switching means that allow a change in the combination between the converter and the load, the battery or the second DC bus being considered as a particular load or power source. It is therefore possible to assign another converter to connect between the battery and the bus using switching means in case the converter is not available. These switching means can operate in real time, thus improving battery utilization and, more generally, the reliability of the aircraft electrical network.

  The invention has been described with reference to an electrical network mounted on an aircraft. Of course, it can be used in any other field, for example in the automotive field, where the use of batteries and consequently the use of batteries is expanding. The battery can be replaced with any other energy storage element such as a capacitor or a supercapacitor. For convenience, in the description that follows, the term battery is used for any energy storage element.

  The present invention will be better understood and other advantages will become apparent upon reading the detailed description of the embodiments given by way of example and illustrated by the accompanying figures.

1 represents an electrical circuit diagram of a network installed on an aircraft. 1 represents in a schematic way the TRUs used in the network of FIG. 1 schematically represents one exemplary embodiment of a converter used in the network of FIG.

  For clarity, the same elements in the various figures are labeled with the same symbols.

  FIG. 1 schematically represents various electrical devices mounted on an aircraft, in particular, a wide-body commercial aircraft. The main generator 10, referred to as MG, is driven by one of the aircraft engines. The generator 10 operates when the aircraft engine is operating and supplying a voltage of 115V to the aircraft AC network 11, for example, at a frequency of 400 Hz. The opening means 12 makes it possible to open the link connecting the generator 10 to the network 11. The auxiliary generator 13 called APU is driven by a turbine dedicated to the generator 13 so as to supply a voltage of 115 V to the AC network 11. Similarly, the opening means 14 makes it possible to open the link connecting the auxiliary generator 13 to the network 11. The turbine works by using aircraft fuel and is utilized when the aircraft is on the ground.

  On the aircraft, DC voltage can be supplied to a high voltage DC power supply bus 21 called HVDC, which is an abbreviation representing “High Voltage Direct Current” connected to the AC network 11. A rectifier 20 is also installed. The voltage normally used for the high voltage DC bus 21 is 540V.

  The DC bus 21 powers several energy converters 22-25, each intended to power a load, for example 26, 27, via a switching means 30. The representation of FIG. 1 is schematic. In fact, one load can be powered by several converters, or one converter can power several loads. A constant load can be supplied with a DC voltage, and the associated converter then converts the voltage on the DC bus 21 to a voltage usable by the load under consideration. In wide aircraft, there are numerous loads that use an AC voltage of 115V at a frequency of 400 Hz. To power these loads, converters 24 and 25 are inverters. Known inverters have the specific function of being reversible.

  Each converter 22-25 can be assigned to various loads 26 and 27 in real time according to the instantaneous demand of each load and according to the operating rate of each converter 22-25. The switching means 30 makes it possible to change the combination between the converters 22-25 and the loads 26 and 27 in real time. The combination of converters 22-25 and loads 26 and 27 is made according to the instantaneous current demand and the instantaneous control mode of the load with which it is associated. The load control mode depends substantially on the load type. Examples commonly used in aircraft include speed, torque or position adjustment, anti-icing or defrosting, constant power operation, and various strategies for engine control (magnetic flux removal, control with or without sensors). Can be.

  The switching means 30 comprises an electrically controlled switch that allows, for example, each converter to be combined with all loads that can be matched with it. “Compatible” means the fact that several loads can operate with the help of the same converter, especially when they require the same power supply with a voltage of 115V, for example at a frequency of 400 Hz. The converter allows the components to produce the same power supply that forms a compatible group. The various components of the group are advantageously identical. This reduces the cost of their production by standardizing the production of converters and allows for simplified aircraft maintenance by having an inventory of only one type of converter. As will be seen below, certain types of converters can produce several different power supplies, depending on the mode of operation of the converter. Therefore, it is possible to combine a load that operates with an AC voltage of, for example, 115 V and 400 Hz and a load that operates with a DC voltage, such as a battery, using the same group of converters.

  Groups can be reconfigured according to the instantaneous demands of loads that can be powered by the group. There is no need for a dedicated converter for each load. In fact, all loads do not work at the same time. The number of converters in the same group is defined according to the instantaneous maximum power that can be consumed by a collection of loads related to one group. This power is less than the sum of the maximum outputs of each load. The switching means 30 thus makes it possible to reduce the number of converters on the machine and hence the mass of these converters.

  Furthermore, reconfiguration allows for improved load utilization. In fact, if one converter fails, another converter in the same group powers a given load and can be replaced immediately. Certain critical loads, such as control of a control wing, for example, can thus be operated with a stable power supply, without requiring dedicated converter redundancy for these controls alone . The collection of converters in the same group then forms a common means that can supply power to one group of loads. Within the same common means, the various converters constituting it are not distinguished.

  A particular load on the network consists of a battery 35 connected via a switching means 30 to one of the converters. In the conventional manner of aircraft, it is known to use a battery with a nominal voltage of DC 28V. Other battery voltages are of course possible for the practice of the present invention. Based on the 540 V DC bus 21, the converter 22 can be operated in such a way that the converter 22 directly supplies a DC voltage of 28 V to the second DC bus 33 that can supply power to the battery 35. A battery charger can be inserted between the second bus 33 and the battery 35 to allow adjustment of the current charging the battery. It is also advantageous to insert a transformation and rectification unit 36 (hereinafter referred to as TRU) between the converter 22 and the battery 35 to charge the battery 35. The TRU 36 is supplied with an AC voltage of 115 V and 400 Hz, and supplies a DC voltage of 28 V. Use of the TRU facilitates the operation of the converter 22, which is used as an inverter that receives a DC voltage of 540V. By means of the switching means 30, it is possible to consider the group formed by the TRU 36 and the battery 35 as a load that can be combined with one of the converters.

  FIG. 2 schematically represents an exemplary TRU 36 comprising a transformer or autotransformer 37 that receives a three-phase 115 V, 400 Hz AC voltage supplied by a converter 22 operating as an inverter. In embodiments where the TRU 36 is located between the converter 22 or 23 and the DC bus 33, the transformer 37 allows the voltage received to be reduced. The transformer 37 supplies a three-phase voltage on the order of 20V, which is once rectified by the rectifier 38 and makes it possible to obtain a DC 28V for supply to the battery 35. The rectifier 38 is made using, for example, a full wave diode bridge that supplies a voltage smoothed by a capacitor.

FIG. 3 schematically represents one exemplary embodiment of converters 22-25 in a simplified manner. The converter includes two terminals 40 and 41, the terminal 40 being connected to the anode of the DC bus 21, and the terminal 41 being connected to the cathode of the DC bus 21. Between terminals 40 and 41, the converter includes three electronic switches, each including T421 and T422 for branch 42, T431 and T432 for branch 43, and T441 and T442 for branch 44. Branches 42, 43 and 44 are provided. In each branch 42, 43 and 44, two switches are connected in series, and one diode is connected in parallel with each switch. The diode symbol is D, followed by the numeric portion of the associated switch symbol, for example, diode D421 is connected to the terminal of switch T421. Each diode is connected in antiparallel to the direction of current flowing from the plus terminal 40 to the minus terminal 41 of the DC bus 21 in each switch. The switches T421 to T442 are all the same, for example, “Insulated”.
Under the IGBT abbreviation “Gate Bipolar Transistor”, it is an insulated gate bipolar transistor type well known in the literature. In each branch 42, 43 and 44, the common points of the two switches are L42, The L43 and L44 self-inductive coils are connected by their first terminals, and the second terminals 46, 47 and 48 of each of the L42, L43 and L44 self-inductive coils respectively supply the three-phase load to the converter. Capacitors C421-C442 are connected between one of terminals 46, 47, and 48 and one of terminals 40, 41. Electrical energy is supplied to the converter by DC network 21. When done, the converter can operate as a voltage inverter. Contrary, when the electric energy in the AC form between the terminals 46, 47, and 48, for example, supplied through the regenerative load or battery, the converter can operate as a rectifier current.

  It is possible to use a TRU 36 with internal means for adjusting the DC voltage fed to the battery 35. However, the adjustment of the voltage supplied to the battery 35 is advantageously performed with the aid of means for operating the converter 22 in combination with the battery 35, for example by changing the duty cycle of the converter 22. The means for ensuring this adjustment comprises a link 39 connecting the TRU 36 to the converter under consideration. The switching means 30 can thus include switches 50 and 51 that allow the selection of a converter connected to the input of the TRU 36. When the converter 22 operates as an inverter for supplying power to the battery 35, the voltage measured at the output of the TRU 36 on the bus 33 is maintained at the DC voltage supplied by the TRU at predetermined intervals, so that the switches T421 to T442. Makes it possible to adapt the open / close duty cycle. The electronic device belonging to the converter 22 can control the opening and closing of the switches T421 to T442. In a known manner, such a device is essential for or combined with each converter so that the switches it contains operate in a consistent manner. Therefore, it is advantageous to use the electronic controller to eliminate the function of adjusting the voltage supplied to the battery 35 of the TRU 36 towards the combined converter. This arrangement also makes it possible to improve the overall reliability of the electrical network. In fact, its reliability is improved by simplifying it as a TRU that no longer contains any internal adjustment means. Furthermore, if the converter's electronic controller fails, it is immediately mitigated by the possible reconfiguration of the converter in the group to which the battery 35 is associated.

  When the battery 35 is used to power the DC bus 21, the reconfiguration of the switching means 30 is done to bypass the TRU 36. In other words, the battery 35 is directly connected to the terminals 46, 47 and 48 without passing through the TRU 36 which is unidirectional. This connection is made by the switching means 30 via the link 52. The converter as represented in FIG. 3 then operates as a single phase booster. More precisely, each branch and its associated self-induction coil makes it possible to increase the voltage supplied by the battery 35. For example, with respect to branch 42, switch T422 is instead used to store energy in self-inductive coil L42 in the form of current through it, and diode D421 instead transfers the stored energy to DC bus 21. Used to release towards the connected terminal 40. The three branches and associated self-induction coils operate with a phase difference of π / 3. The converter may be controlled to function as a multi-phase inverter for supplying power to the battery 35 via the TRU 36 or to function as N single-phase boosters for supplying power to the DC bus 21 from the battery. Here, N represents the number of phases of the inverter, and the N boosters are phase-shifted by π / N.

  The operation as N single-phase boosters presents a drawback when the voltage on the DC bus 33 is significantly lower than the voltage on the DC bus 21. The efficiency of the converter is then not very good. In order to alleviate this drawback, a TRU capable of supplying power from the second bus 33 to the first bus 21 can be inserted between the first DC bus 21 and the selected converter. The TRU is equipped with a transformer that allows the voltage received to rise. This embodiment requires that the converter be completely disconnected in order to connect the converter terminals 40 and 41 to the low voltage DC bus 33 rather than to the HVDC DC bus 21. The TRU is then connected between one terminal 46, 47, and 48 and the HVDC DC bus 21.

  In a more general manner, an inverter as represented in FIG. 3 operates in a first direction when it receives energy from the bus 21 as a multiphase inverter or as N step-down DC / DC converters. obtain. The inverter can also operate in a second direction opposite to the first, as a current rectifier when it receives an alternating voltage from a regenerative load, or as N step-up DC / DC converters. The operation of the converter can be changed in real time simultaneously with the switch of the switching means 30.

  This type of reversible DC / AC converter, which can be driven in step-up or step-down DC / DC mode, is much easier to manufacture and much more reliable than a bidirectional DC / DC converter including a high frequency transformer. high.

Claims (11)

Group of devices can be supplied or consumed electric energy (21,26,27,35,36),
Transmission means that is selectively connected between a first device and a second device in the device group (21, 26, 27, 35, 36) and enables energy exchange between the two devices. An electrical network including and
It said transmission means comprises a reversible DC / AC converter (22, 23, 24, 25), reversible manner DC / AC converter can be driven by the DC / DC mode buck or boost
Care network power, characterized in that. The first device is a power supply bus (21), and the second device is a second device (26, 27, 35, 36) other than the power supply bus,
A plurality of the reversible DC / AC converters (22, 23, 24, 25) are provided, and each of the plurality of reversible DC / AC converters (22, 23, 24, 25) includes the first device (21). And energy exchange between the second device (26, 27, 35, 36),
Switching means (30) enabling a change in the connection combination between the reversible DC / AC converter (22, 23, 24, 25) and the second device (26, 27, 35, 36) Further prepare
Electrical network according to 請 Motomeko 1, characterized in that. All of the reversible DC / AC converter (22, 23, 24, 25) is, 請 Motomeko 2 you, characterized in that able to exchange each energy of said second device (26,27,35,36) Electrical network as described in. All of the reversible DC / AC converter (22, 23, 24, 25) is an electrical network according to 請 Motomeko 3 you characterized as having the same configuration. The first device is a power supply bus (21), and the second device is a battery (35) and a second power supply bus (33) connected to the battery (35). electrical network according to any one of 請 Motomeko 1-4 you characterized. 請 Motomeko 5 you comprising a transformer and a rectifier unit (36) in between said reversible DC / AC converter (22, 23, 24, 25) a second power supply bus (33) Electrical network as described in. It said transformer and a rectifier unit (36) is an electrical network according to 請 Motomeko 6 you further comprising a transformer which allows to lower the power receiving voltage. The operation of the reversible DC / AC converter (22, 23, 24, 25), electrical described 請 Motomeko 6 or 7, wherein adjusting the voltage of the second power supply bus (33) Network. Between the power supply bus (21) of the device group (21, 26, 27, 35, 36) and the reversible DC / AC converter (22, 23, 24, 25), the device group (21 , 26, 27, 35, and 36), the power supply bus (21) is connected to the battery (35) connected to the battery (35), and the power supply bus (21) is provided with a transformer and rectifier unit. electrical network as claimed in any one of 請 Motomeko 1-8 you wherein a. A transformer that enables the transformer and rectifier unit located between the power supply bus (21) and the reversible DC / AC converter (22, 23, 24, 25) to increase the received voltage; electrical network according to 請 Motomeko 9 you, comprising. The reversible DC / AC converter (22, 23, 24, 25) can function as a multi-phase inverter or as N single-phase boosters, where N represents the number of phases of the inverter and N boosters are π / N only electrical network according to any one of 請 Motomeko 10 you characterized by being phase-shifted.

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