Onboard aeronautical power circuit with active filtering and corresponding aircraft

Abstract

Circuit (1), comprising an input line (2), an output line (3), and a main switching converter (4) having an input connected to the input line and an output connected to the output line and producing operating harmonics, the circuit comprising at least one additional DC / AC converter (5) mounted in parallel with the main converter and arranged to inject, onto the line carrying the sinusoidal signal and in synchronization with the sinusoidal wave, an additional signal that is a function of the operating harmonics of the main converter, the additional converter comprising at least one broadband semiconductor switching stage (7). ABBREVIATED FIGURE: Fig. 1

Description

Title of the invention: On-board aeronautical power circuit with active filtering and corresponding aircraft

[0001] The present invention relates to the field of electrical circuits and more particularly those containing a load capable of generating disturbances on the circuit, in particular a load comprising switching transistors generating current harmonics linked to their switching frequencies.

[0002] BACKGROUND OF THE INVENTION

[0003] In aircraft, the power supply to electrical equipment is provided via an on-board aeronautical network comprising a generator driven in rotation by at least one of the aircraft's engines to form a source of alternating current.

[0004] In order to limit the pollution generated by aircraft, the on-board aeronautical network includes an increasing number of on-board electrical equipment including switching converters which generate harmonics likely to disturb other equipment in the network. It is recalled that harmonics are ripples which are carried by the main sinusoidal wave defined at the switching frequency and which have a frequency which is a multiple of that of the main sinusoidal wave.

[0005] To eliminate these harmonics, it is known to use passive filters. However, a passive filter is all the heavier and more cumbersome the larger the frequency range to be attenuated, characteristics which are particularly detrimental in the field of transport and more particularly air transport. In addition, these passive filters alter the dynamics of the converters with which they are associated.

[0006] Another solution is to design converters which naturally reject few harmonics, but these converters are expensive and not necessarily suitable for all applications and in particular those concerning the so-called "more electric" or MEA (More Electrical Aircraft) aircraft.

[0007] Low-frequency, low-power land-based electrical networks are also known which include active filters for attenuating harmonics which are present on the network and depend on the network frequency. However, in an on-board aeronautical network including switching converters, the frequency of the harmonics to be attenuated is linked to the switching frequency of the converters which can be very high, generally at least equal to 10 kHz, so that these active filters are unsuitable for aeronautical use.

[0008] SUBJECT OF THE INVENTION

[0009] The invention aims in particular to provide an electronic power circuit promoting power transfer and limiting the disturbances caused by a switching converter present in the circuit. Summary of the invention

[0010] For this purpose, there is provided, according to the invention, an electrical power circuit according to claim 1.

[0011] Thus, the additional converter plays the role of an active switching filter and allows non-linear filtering.

[0012] The invention has two applications in particular.

[0013] In the first, the input power signal is the sinusoidal signal and the output power signal is the continuous signal; the additional converter being arranged so that the additional signal corresponds substantially to the operating harmonics present.

[0014] This application corresponds for example to the rectification of the sinusoidal input power signal supplied by a generator to obtain the continuous output power signal: the main converter is a rectifier for example of the PWM (pulse width modulation) type. The generator then provides only the main wave and the additional converter provides the operating harmonics of the main converter. The harmonic disturbances for the other equipment which would be connected to the generator are limited and a passive filter can be associated with the additional converter to filter the disturbances at frequencies higher than the operating harmonics of the main converter: the passive filter will only have to filter relatively high frequencies and can therefore have a relatively small size and mass.Preferably, a passive filter will be chosen capable of filtering the frequencies of the operating harmonics of the additional converter which have a frequency 10 to 20 times higher than that of the operating harmonics of the main converter. It is therefore understood that the invention is a high-frequency switching structure, controlled using a servocontrol, to construct the current waveforms of the harmonics of the switching frequencies rejected by the main converter 5 on the input line connected to the network.

[0015] In the second, the input power signal is the continuous signal, the output line being connected to a synchronous machine powered by the output power signal which is the sinusoidal signal; the additional converter being arranged so that the additional signal attenuates the operating harmonics present on the output power signal.

[0016] This application corresponds for example to the power supply of an electrical machine: the main converter is then an inverter which converts the input power signal so as to provide the sinusoidal output power signal. The An additional converter is used to minimize residual ripples from cutting by attenuating operating harmonics present in the output power signal. This ensures more precise control of the machine.

[0017] We further propose a circuit as previously described, in which the additional converter comprises a control stage.

[0018] We further propose a circuit as previously described, in which the control stage comprises an additional signal synchronization module with sinusoidal background.

[0019] We further propose a circuit as previously described, in which the control stage comprises a module for developing current setpoints and a control module using the current setpoints to control the switching stage.

[0020] A circuit as previously described is further proposed, in which the current setpoint generation module receives as input a measurement of a current drawn by the main converter, a measurement of a voltage of the input line upstream of the additional converter, a measurement of the DC voltage at the output of the additional converter and a reference DC voltage at the output of the additional converter.

[0021] We further propose a circuit as previously described, in which the control module receives as input a measurement of the currents generated by the additional converter.

[0022] A circuit as previously described is further proposed, in which the input power signal is the sinusoidal signal and the output power signal is the continuous signal; the additional converter being arranged so that the additional signal corresponds substantially to the operating harmonics.

[0023] A circuit as previously described is further proposed, in which the input power signal is the continuous signal, the output line being connected to a synchronous machine powered by the output power signal which is the sinusoidal signal; the additional converter being arranged so that the additional signal attenuates the operating harmonics generated on the output power signal by the main converter.

[0024] A circuit as previously described is further proposed, in which the additional converter is arranged to have a switching frequency of approximately 1 MHz, and in which the additional converter is of the gallium nitride semiconductor type.

[0025] An aircraft is further proposed comprising at least one circuit as previously described.

[0026] Other characteristics and advantages of the invention will emerge on reading the following description of particular and non-limiting embodiments of the invention. Brief description of the drawings

[0027] Reference will be made to the accompanying drawings, among which:

[0028] [Fig-1] [Fig.l] is a block diagram of the invention;

[0029] [Fig.2] [Fig.2] is a diagram showing, as a function of time, the amplitude of the current absorbed by the network, the rectifier and the active filter according to this principle;

[0030] [Fig.3] [Fig.3] is a diagram showing the spectrum of the current absorbed by the network, the rectifier and the active filter, the frequency being on the abscissa and the amplitude on the ordinate;

[0031] [Fig.4] [Fig.4] is a diagram illustrating a first application of the invention;

[0032] [Fig.5] [Fig.5] is a diagram illustrating a second application of the invention;

[0033] [Fig.6] [Fig.6] is a simplified diagram of the first application of the invention, defining the currents produced in the first application;

[0034] [Fig.7] [Fig.7] is a simplified diagram of a control stage of the active filter according to the invention for this first application;

[0035] [Fig.8] [Fig.8] is a flowchart illustrating the process of developing the setpoint currents in this control stage;

[0036] [Fig.9] [Fig.9] is a block diagram illustrating the process of developing the setpoint currents in the control stage for a single-phase application;

[0037] [Fig. 10] [Fig. 10] is a block diagram illustrating the process of developing the setpoint currents in the control stage for a three-phase application;

[0038] [Fig. 11] [Fig. 11] is a block diagram illustrating the current fork control process in the control stage;

[0039] [Fig. 12] [Fig. 12] is a block diagram illustrating the pulse width modulation control process in the control stage;

[0040] [Fig. 13] [Fig. 13] is a diagram of an active filter according to a first embodiment of the invention;

[0041] [Fig. 14] [Fig. 14] is a diagram of an active filter according to a second embodiment of the invention;

[0042] [Fig. 15] [Fig. 15] is a diagram of an active filter according to a third embodiment of the invention, producing compensation currents at the switching frequency;

[0043] [Fig. 16] [Fig. 16] is a diagram of an active filter according to a fourth embodiment of the invention, usable for a polyphase application;

[0044] [Fig. 17] [Fig. 17] is a diagram showing a first possible association of active filters according to the first or second embodiment of the invention, usable for polyphase application, with a neutral connection;

[0045] [Fig. 18] [Fig. 18] is a diagram showing a second possible association of active filters according to the first or second embodiment of the invention, usable for polyphase application, without neutral connection. DETAILED DESCRIPTION OF THE INVENTION

[0046] With reference to the figures, the invention is described here in application to an aircraft A comprising at least one on-board aeronautical power circuit generally designated 1.

[0047] [Fig.l] illustrates the principle of the invention.

[0048] The circuit 1 comprises an input line 2 carrying an input power signal, an output line 3 carrying an output power signal, and a main switching converter 4 having an input connected to the input line 2 and an output connected to the output line 3. The input line 2 is connected to a network RES comprising a source S of electrical energy with alternating voltage and carries an input power signal. The output line 3 is connected to a load C and carries an output power signal supplying the load C. The input power signal is a sinusoidal signal having at least one sinusoidal wave produced by the source S and the output power signal is a continuous signal produced by the main converter 4. The main converter 4 is here a pulse width modulation (PWM) rectifier.In operation, the main converter 4 produces operating harmonics which depend on its switching frequency and calls for a corresponding current which is superimposed on the sine wave.

[0049] The circuit 1 comprises an additional DC / AC converter 5 mounted in parallel with the main converter 4. The additional converter 5 has an input connected to the output line 3 to be supplied with DC current and an output connected to the input line 2, and is arranged to inject, on the input line 2, in synchronization with the sinusoidal wave, an additional signal depending on the operating harmonics of the main converter 4. More precisely here, the additional converter 5 is arranged so that the additional signal corresponds substantially to the operating harmonics of the main converter 4.

[0050] Circuit 1 comprises a passive filter 6 mounted on input line 2 between source S and the connection point of additional converter 5 to input line 2.

[0051] We can see in [Fig.2] the current iRES absorbed by the network (i.e. upstream of the connection point of the additional converter 5 to the input line 2), the current iHF absorbed by the additional converter 5 and the current iBF absorbed by the main converter 4. We can thus see that the current absorbed by the main converter 4 (iBF) is the sum of a current, corresponding to the operating harmonics of the main converter 4, supplied by the additional converter 5 and the sinusoidal current wave supplied by the source S (Ires)-

[0052] The additional converter 5 also generates operating harmonics and the passive filter 6 is arranged to attenuate or even eliminate these operating harmonics and prevent them from passing onto the RES network. In [Fig. 3] are represented the spectrum of the current i^s absorbed by the network, the spectrum of the current i Hp absorbed by the additional converter 5 and the spectrum of the current iBF absorbed by the main converter 4. It can be seen in this figure that the harmonics of the current iBF have disappeared from the network current iRES.

[0053] The structure of the passive filter 6 is known in itself and will not be detailed further here. It will be noted that the additional converter 5 has a switching frequency which must be ten to twenty times higher than that of the main converter 4. The passive filter 6 is therefore a filter arranged to eliminate harmonics having a high frequency typically greater than or equal to 1 MHz. The components necessary for such filtering are relatively compact and light.

[0054] The additional converter 5 will now be described in more detail with reference to FIGS. 4, 6 to 8, 10 and 11.

[0055] The source S is for example a generator which is driven in rotation by an auxiliary motor (or APU from the English Auxiliary Power Unit) or any other generator of the aircraft A and therefore produces a three-phase alternating current in the form of sinusoidal waves.

[0056] With reference to [Fig.4], the additional converter 5 comprises a switching stage 7 having an input connected to a power supply stage 8 and an output connected to an injection stage 9.

[0057] The switching stage 7 comprises transistors here of the MOSFET type controlled by a control stage 10 to convert the direct current from the power supply stage 8 connected to the output line 3 into an alternating current supplied to the injection stage 9 which is connected to the input line 2 and which here incorporates the passive filter 6 (for example, a connector with integrated current and / or voltage measurement is used). To this end, the control stage 10 comprises a module for developing current setpoints 11 and a control module 12 controlling the transistors from the control setpoints, and is connected to a measurement module 13 arranged on the input line 2 between the injection stage 9 and the main converter 4. The control stage 10 here implements class D amplifiers.The switching stage 7 is here of the wideband semiconductor type (or wide gap technology) and more particularly in gallium nitride and arranged to operate at switching frequencies at least equal to 1 MHz. The additional converter can thus easily ensure compensation of harmonics in a 10kHz - 100kHz band.

[0058] The control stage 10 and its operation will be detailed with reference to figures 6 to 8, 10 and 11.

[0059] In [Fig.6], the current supplied by the network is called ires, the current supplied by the additional converter 5 is called iFAHF and the current called by the main converter 4, which is the sum of the currents ires and iFAHF, is called iConv.

[0060] Also referring to [Fig.8], the current setpoint generation module 11 receives as input a measurement of the current iConv drawn by the main converter 5, a measurement of a voltage vres of the network upstream of the input line 2, a measurement of a continuous voltage vDCFAHf at the output of the additional converter 5 and a reference continuous voltage vDCref at the output of the additional converter 5.

[0061] With reference to [Fig. 10], the measurement of the current iConv of each of the phases a, b, c arrives at a first input of a transformation module 111 having an output connected to a low-pass filter 112 whose output is connected to a first input of an adder 113 having an output connected to an input of an inverse transformation module 114 connected to a negative input of a subtractor 115. More precisely, in the transformation module 111, the measurement of current iConv of each of the phases a, b, c undergoes a Clarke transformation to obtain current values ​​ia and ip which are subjected to a Park transformation to obtain current values ​​id and iq. Only the current value id arrives at the first input of the adder 113, the filtered current value arriving directly at the inverse transformation module 114.In the inverse transformation module 114, the current values ​​id and iq are subjected to an inverse Park transformation to obtain current values ​​ia and ip which are subjected to an inverse Clarke transformation to obtain phase currents a, b, c.

[0062] The measurement of the current iConv of each of the phases a, b, c also arrives in a filter 116 having an output connected to a positive input of the subtractor 115.

[0063] The measurement of the network voltage vres is introduced into a synchronization module 117 making it possible to synchronize the additional signal with the sinusoidal wave. The synchronization module is for example an analog or digital phase-locked loop (PLL) module. The synchronization module is arranged, in a manner known per se, to lock onto the specific frequency of the current ires and separate the different components of the current. The synchronization module is for example of the SOGI type (second-order generalized integrators).

[0064] The voltage measurement vDCFAHf and the reference DC voltage vDCref arrive respectively at a positive input and a negative input of a summer 118 having an output connected to the input of a corrector 119. The corrector 119 has an output connected to a second input of the summer 113.

[0065] The adder 115 has an output providing the current setpoints iconSFAHF-

[0066] With reference to [Fig. 11], the control module 12 receives as input a measurement of the iFAHF currents generated by the additional converter 5 and the current setpoints iconsFAHF- The measurement of the iFAHF currents generated by the additional converter 5 and the current setpoints iconsFAHF arrive respectively at a negative input and a positive input of a summer 121 having an output connected to the input of a module by hysteresis 122 allowing a current range control having a split and complementary output to provide ComH and ComL commands.

[0067] The operating mode of the control stage 10 is illustrated in [Fig.8]. It is recalled that the additional converter 5 is not intended to supply active power to the main converter 4. It is therefore necessary to extract the fundamental component of the current of the main converter 4 which carries the power. The current to be compensated therefore corresponds to the total current reduced by its fundamental component and / or any other low-frequency component that one does not wish to compensate. This is what the current setpoint development module 11 makes possible.

[0068] The network voltage system (v»-«v) is measured to enable the detection of the frequency and phases using the synchronization module 117 (operation 210). The network phase is used to transform (by using the Park transform in the transformation module 111) the alternating currents at the input of the converter (icom ) into their quasi-constant transforms. The low-pass filtering of these transformed quantities by the filters 112 makes it possible to extract the amplitude of the fundamental component of the currents (operation 220).

[0069] A DC component from the corrector 119, allowing the control of the DC voltage of the additional converter 5 C'dcfahfY is added to the DC value defining the fundamental component of the current of the additional converter 5 (summator 113) before carrying out the inverse transformation implemented by the inverse transformation module 114 (operation 230). The inverse transforms of the DC quantities are subtracted from the currents (subtractor 116 — operation 240) to define the reference currents (iconsFAtîF)-

[0070] The control module 12 makes it possible, from the difference between the currents measured at the level of the additional converter 5 and the reference currents from the reference current generation module 11, to generate the control signals for the transistors (ComH ComL) of the switching stage 7 using hysteresis comparators. The hysteresis width directly defines the amplitude of the residual current ripples flowing on the RES network.

[0071] In the first embodiment shown in [Fig. 13], the additional converter 5 has two switching stages, one associated with phase L and the other with neutral N of the RES network.

[0072] In the second embodiment shown in [Fig. 14], the additional converter 5 has a single switching stage per phase L of the network RES. There is no switching stage for the neutral N.

[0073] In the third embodiment shown in [Fig.15], the additional converter 5 has two switching stages per phase L of the network RES. There is no switching stage for the neutral N.

[0074] In the fourth embodiment shown in [Fig.16], the additional converter 5 has a single switching stage per phase L1, L2, L3 of the network RES. There is no switching stage for the neutral N.

[0075] In these four embodiments, the power supply of the additional converter 5 comes from an energy storage device 14 such as an accumulator supplying a direct current to the switching stage 7. The accumulator 14 can be produced by capacitors.

[0076] In the first and last two embodiments, the additional converter 5 comprises a common current setpoint generation module 11 connected to several control modules 12 each associated with one of the switching stages 7.

[0077] It is furthermore possible to provide, as illustrated in FIGS. 17 and 18, several additional converters 5 each connected to one of the phases L1, L2, L3.

[0078] In the implementation of [Fig. 17], the three additional converters 5 are connected together to the neutral N of the three-phase line.

[0079] In the implementation of [Fig. 18], the three-phase line is devoid of neutral. It is planned to connect the additional converters 5 to a capacitive connection block 15 comprising three capacitors each connected to one of the phases L1, L2, L3 of the three-phase line.

[0080] In the second possible application of the invention, shown in [Fig. 5], the input line 2 of the main converter 4 carries a direct power signal and the output line 3 is connected to a synchronous machine and carries a sinusoidal output power signal. The synchronous machine forms the load C. The additional converter 5 is arranged so that the additional signal attenuates the operating harmonics present on the output power signal. This application concerns, for example, the control of a motor by means of an inverter, formed by the main converter 4, transforming a direct current into alternating current of variable frequency depending on the desired speed of the motor.

[0081] The structure of the additional converter 5 is substantially identical to that previously described. It comprises a switching stage 7 having an input connected to a power supply stage 8 and an output connected to an injection stage 9. The switching stage 7 comprises transistors here of the MOSFET type controlled by a stage of control 10 to convert the direct current from the power supply stage 8 connected to the output line 3 into an alternating current supplied to the injection stage 9 which is connected to the input line 2 and which here incorporates the passive filter 6. This alternating current comprises sinusoidal waves which provide the power necessary for the load C.

[0082] The control stage 10 is connected to a measurement module 13 arranged on the output line 3 between the injection stage 9 and the main converter 4. The control stage 10 has the same structure as previously and operates on the same principle, it is its programming which changes since its function is to attenuate or even eliminate the harmonics which are superimposed on the sinusoidal background of the output power signal by the main converter 4 and which constitute operating noises thereof.

[0083] It will nevertheless be noted that, in this application, it is more difficult to synchronize the additional signal on the sinusoidal wave of the output signal because the characteristics of the sinusoidal wave, and in particular its frequency, depend on the desired rotation speed of the synchronous machine. It is also more difficult because the output voltages of the main converter 4 are less clean than those supplied by a network such as that of the first application.

[0084] Of course, the invention is not limited to the embodiments described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0085] In particular, the additional converter according to the invention may have a structure different from that described.

[0086] The inductances noted in [Fig.l] may or may not belong to the converters.

[0087] The development of current instructions preferably includes the following steps: - synchronization with the network; - extraction of the fundamental component of the current absorbed by the power converter; - subtraction of the fundamental component and the converter current; - addition of a current component in phase with the network voltage allowing regulation of the continuous voltage of the active HF filter.

[0088] However, the order and / or content of all or part of these steps may be modified.

[0089] The passive filter 6 can be integrated into the additional converter or be external to it.

[0090] The fork control or current hysteresis control can be replaced by another control and for example a pulse width modulation control according to [Fig. 12]. The control module 122 is then replaced by a correction module 123 connected to a pulse width modulation module 124.

[0091] The operation of the additional converter can be assisted by an HVDC bus existing.

[0092] The invention has been described in application to a three-phase network. The invention is obviously adaptable to a network comprising less than three phases, such as a single-phase network, or more than three phases.

[0093] The switching stage can be made of any wide band or wide gap semiconductor and not only gallium nitride.

[0094] The structure of the additional converter can be easily adapted to increase the effective frequency of the compensation currents at the switching frequency of the additional converter. For example, a decoupled or coupled interlaced structure can be used to create the switching stage.

Claims

Claims

1. On-board aeronautical power circuit (1), comprising an input line (2) carrying an input power signal, an output line (3) carrying an output power signal, and a main switching converter (4) having an input connected to the input line and an output connected to the output line and producing operating harmonics, one of the power signals being a sinusoidal signal having at least one sinusoidal wave and the other of the power signals being a DC signal, characterized in that the circuit comprises at least one additional DC / AC converter (5) mounted in parallel with the main converter and arranged to inject, on that of the two lines carrying the sinusoidal signal and in synchronization with the sinusoidal wave, an additional signal depending on the operating harmonics of the main converter,and in that the additional converter comprises at least one broadband semiconductor switching stage (7).

2. Circuit according to claim 1, in which the additional converter comprises a driving stage (10).

3. Circuit according to claim 2, in which the driving stage (10) comprises a synchronization module (117) of the additional signal with the sine wave.

4. Circuit according to claim 2, in which the control stage (10) comprises a module for developing current setpoints (11) and a control module (12) using the current setpoints to control the switching stage (7).

5. Circuit according to claim 4, in which the current setpoint development module (11) receives as input a measurement of a current drawn by the main converter, a measurement of a voltage of the input line upstream of the additional converter, a measurement of the DC voltage at the output of the additional converter and a reference DC voltage at the output of the additional converter.

6. Circuit according to claim 4, in which the control module (12) receives as input a measurement of the currents generated by the additional converter.

7. A circuit according to claim 1, wherein the input power signal is the sinusoidal signal and the output power signal is the DC signal; the additional converter (5) being arranged so that the additional signal corresponds substantially to the operating harmonics.

8. A circuit according to claim 1, wherein the input power signal is the DC signal, the output line (3) being connected to a synchronous machine powered by the output power signal which is the sinusoidal signal; the additional converter (5) being arranged so that the additional signal attenuates the operating harmonics generated on the output power signal by the main converter (4).

9. A circuit according to any preceding claim, wherein the additional converter (5) is arranged to have a switching frequency of approximately 1 MHz, and wherein the additional converter (5) is of the gallium nitride semiconductor type.

10. Aircraft comprising at least one circuit according to any one of the preceding claims.

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