Power and data transmission device with power signal frequency control, and aircraft incorporating such a device.

Abstract

A power and data transmission device comprising a first circuit (100), a second circuit (200), and a cable (300) connecting the first and second circuits and having a first pair (301) and a second pair (302) of electrical conductors for transmitting a data signal and a power signal, the data signal being transmitted in differential mode in one direction on the first pair of electrical conductors and in the second direction on the second pair of electrical conductors. The first circuit is arranged to transmit the power signal in differential mode on a sinusoidal carrier using the common modes of the two pairs of conductors, and the second circuit is arranged to receive said power signal while maintaining with respect to the cable a real impedance equal to an iterative impedance of the cable.The first circuit (100) comprises a first transformer (104) connected to the first pair (301) of electrical conductors, a second transformer (105) connected to the second pair (302) of electrical conductors, and a third transformer (106) in common mode across both pairs of electrical conductors. A capacitor (110) is placed in parallel with a primary winding (106.1) of the third transformer (106). Aircraft comprising such a device. FIGURE FROM THE ABRIDGED: Fig. 1.

Description

Title of the invention: Power and data transmission device with power signal frequency control, and aircraft comprising such a device.

[0001] The present invention relates to the field of data transmission between two remote electronic devices, and in particular two electronic devices on board a vehicle, such as an electronic control unit and a data concentrator or a sensor.

[0002] BACKGROUND OF THE INVENTION

[0003] In the aeronautical field, the need to ensure the maintenance of aircraft safety and performance has led to an increase in the number of sensors present on aircraft and their distribution throughout the structure and equipment of said aircraft.

[0004] The physical quantities measured by these sensors are of all types and it is necessary to limit as much as possible the intrusive nature of their implantation in the aircraft or its equipment in order to facilitate said implantation and minimize as much as possible the increase in mass linked to the addition of the sensors.

[0005] Two particularly demanding aspects of this implementation concern, firstly, the transmission of data between the sensors and the electronic data processing unit, which is generally a central computer forming part of the aircraft's electronic control system, and secondly, the power supply to said sensors. Large and / or complex aircraft carry a large number of sensors. The sensors are then grouped, for example, according to their position in the aircraft, and the sensors in each group are connected to a data concentrator, which is itself connected to the electronic processing unit. The means implemented for both data transmission and the power supply to the data concentrators and sensors must be relatively lightweight, minimally intrusive, reliable, and require minimal maintenance.Naturally, data transmission via radio waves and battery power are considered, but they do not meet all the constraints mentioned above.

[0006] In fact, the ARINC 664 (or AFDX) standard was chosen for data transmissions on aircraft. The implementation of this standard relies on a wired link comprising a shielded differential double-pair cable capable of carrying two opposing data streams (commonly referred to as Tx and Rx) at a bit rate of 125 Mbit / s.

[0007] A data link system allowing power supply via power line carrier is also known, notably from document FR-A-3049790, such that a power signal travels on the same cable as the data signal. The main difficulties encountered are preventing the power signal from interfering with the data signal and supplying the concentrators and sensors with the highest possible efficiency.

[0008] SUBJECT OF THE INVENTION

[0009] The invention aims in particular at a linking system between two electronic devices, which allows a common transport of a data signal and a power supply signal while limiting the risk of interference of the first signal by the second, while having a power supply with a sufficiently high efficiency. Summary of the invention

[0010] To this end, a power and data transmission device is provided, comprising a first circuit, a second circuit, and a cable connecting the first and second circuits, and having a first pair and a second pair of electrical conductors for transmitting a data signal and a power signal, the data signal being transmitted in differential mode in a first direction on the first pair of electrical conductors and in a second direction on the second pair of electrical conductors. According to the invention: - the first circuit is arranged to emit the power signal in differential mode on a sinusoidal carrier using the common modes of the two pairs of conductors and the second circuit is arranged to receive said power signal while maintaining with respect to the cable a real impedance equal to an iterative impedance of the cable; - the first circuit includes a first transformer connected to the first pair of electrical conductors, a second transformer connected to the second pair of electrical conductors, and a third transformer in common mode on both pairs of electrical conductors; - a capacitor is mounted in parallel with the third transformer.

[0011] The use of a sinusoidal carrier wave ensures optimal coexistence of data and power signals on the same cable. Such a cable, like a conventional coaxial link, is characterized by an iterative impedance, meaning that its actual impedance is repeated step by step along its entire length. When a line with an iterative impedance is loaded by a resistance equal to its iterative impedance (often referred to as its characteristic impedance), its input presents an actual impedance equal to the resistance loading it at its end, regardless of the line's length. When a line with iterative impedance is loaded with its characteristic impedance, the signals propagate along the line without causing echoes (local overvoltages and / or overcurrents) that would promote parasitic coupling. Thus, matching the line to its iterative or characteristic impedance prevents standing waves on the AC power signal: such standing waves would cause antinodes or nodes in currents or voltages, and would likely increase parasitic coupling between common-mode power transmission and differential-mode data transmission. There is therefore effective segregation between power and data signals. To this end, the second circuit is designed to load the cable with a constant pure resistance even when the load is variable.Power transmission using sinusoidal voltage and current limits their bandwidth and therefore reduces high-frequency coupling. Even more preferably, the power signal carrier is centered on a much lower frequency than the binary data streams. This facilitates segregation by filtering.

[0012] The transformers provide galvanic isolation which, in combination with AC power transmission, makes it possible to protect all or part of the circuit from lightning and bulk current injection (BCI). The device thus benefits from lightning and BCI resistance without requiring specific protection components that are expensive, bulky, and difficult to test; while minimizing interface wiring and ensuring a maximum bit error rate.

[0013] It is known that electrical efficiency is degraded by phase shift (Δ) when the load is not adapted to the frequency of the line supply voltage (the power factor, or cos(Δ) <t>), is less than 1). Indeed, the first circuit must supply a current equal to the sum of the reactive current (that consumed, notably in the inductors) and the active current (the useful current), and the power supply efficiency is maximized when the reactive current is zero. Since the line has an overall inductive behavior (and therefore consumes reactive current), the capacitor placed in parallel with the primary of the third transformer (which is the power transmission transformer) will provide overall compensation of the reactive current to the entire transformer, line, and load system, thus improving the overall efficiency. The first circuit is loaded only by a real impedance, and the current is minimized to only its component useful for the transfer of electrical energy (the active current).It should be noted that the compensation value is very little dependent on the line and the second circuit (and the load possibly connected to the second circuit) because the transmission takes place on a line matched (on its characteristic impedance) and loaded by a real impedance and, at the line input, . The sinusoidal signal is loaded by a real, known, and constant impedance, regardless of the line length. Furthermore, a line disconnection (or a power failure in the second circuit) can be clearly detected by this device by observing the compensation required, because in the event of a fault, the current drawn by the line becomes predominantly reactive.

[0014] The efficiency of the power supply provided by the first circuit is therefore relatively high and sufficient for many applications. However, the device thus arranged exhibits sensitivity to the intrinsic values ​​of the analog components constituting the chain connecting the first circuit to the load. Indeed, the inductive component of the load originates largely from the magnetizing inductance of the coupling transformer. By using transformers comprising windings made up of traces on printed circuit boards and magnetic cores embedded in said printed circuit boards, it is possible to minimize the dispersions, which are nevertheless still estimated to be within a range of + / - 5% (dispersions in manufacturing characteristics and temperature of the magnetic core).These variations in characteristics lead to a degradation of the power factor, which deviates from its optimal value of 1.

[0015] According to a particularly advantageous feature of the invention, the primary winding of the third transformer is connected to a servo circuit arranged to control a frequency of the power signal to a cancellation of a voltage / current phase shift of the power signal.

[0016] The frequency of the supply voltage is controlled to cancel the phase shift between the supply voltage and the resulting current or, in other words, to maintain the power factor at 1. This is made possible because the most important characteristic of the sinusoidal supply signal for the operation of the power supply system is the sinusoidal waveform which guarantees the lowest dV / dt and therefore minimized electromagnetic disturbances, while the power supply system is not very sensitive to the frequency of the sinusoidal supply signal as long as it is close to a nominal operating frequency and for example within a range of about + / - 20% around the nominal operating frequency.

[0017] According to optional features, used individually or in whole or in part in any technically feasible combination: - the primary winding of the third transformer is connected to a servo circuit arranged to control a frequency of the power signal to a cancellation of a voltage / current phase shift of the power signal; the control circuit includes a phase comparator arranged to compare the phase of the current with the phase of the voltage and produce at the output a voltage representative of a difference between the phases; the phase comparator includes a voltage amplifier and a voltage comparator to provide at output a sinusoidal voltage phase reference signal, a current amplifier and a current comparator to provide at output a sinusoidal current phase reference signal, a rising edge sensitive logic flip-flop to compare the sinusoidal voltage phase reference signal and the sinusoidal current phase reference signal in opposite phase and obtain an output signal having a duty cycle; the control circuit includes an error integrator / amplifier receiving as input the output signal from the phase comparator and a reference voltage and having an output connected to a voltage-controlled oscillator driving a class D power amplifier having an output providing the power signal; the control circuit includes a digital counter receiving as input the output signal from the phase comparator and a clock signal and having an output connected to an oscillator controlled by a digital input controlling a class D power amplifier having an output providing the power signal; the output of the class D power amplifier, is connected to a filter arranged to attenuate odd harmonics and a DC component of the power signal; the first circuit is arranged so that the power signal has an alternating voltage with a high frequency, preferably on the order of megahertz; The second circuit includes: an AC / DC converter (208) receiving the power signal as input and providing a DC power signal with a rectified voltage as output; an electronic load arranged to be proportional to the rectified voltage; the AC / DC converter is associated with a filter arranged to attenuate switching noise from the AC / DC converter, the filter preferably comprising a common-mode mutual inductance; the electronic load includes a current consumer that follows the rectified voltage and is connected to the output of the AC / DC converter; - The device includes a low-pass filter Pi positioned at the output of the current consumer and matched to the iterative impedance of the cable.

[0018] The invention also relates to an aircraft comprising a data processing device connected to the first circuit (100) of such a remote link device for connecting an electronic data processing unit to a data concentrator or to a sensor.

[0019] Other features and advantages of the invention will become apparent from the following description of particular, non-limiting embodiments of the invention. Brief description of the drawings

[0020] Reference will be made to the attached drawings, among which:

[0021] [Fig. 1] is an overview of the circuit of the transmission device according to the invention;

[0022] [Fig.2] is an overview of the circuit of the second circuit of this device transmission device, according to a first embodiment of the second circuit;

[0023] [Fig.3] is a partial view of the second circuit according to a variant of this first embodiment;

[0024] [Fig.4] is an overview of the second circuit of this transmission device, according to a second embodiment of the second circuit;

[0025] [Fig.5] is a partial view of the first circuit of the transmission device according to the invention, showing more particularly the frequency control circuit of the power signal according to a first embodiment of the invention;

[0026] [Fig.6] is a chronograph showing the current and voltage in sinusoidal form, the results of the outputs of the analog comparators of the control circuit, the opposite of the current ( / I), as well as the output of the phase comparator (¢);

[0027] [Fig.7] is a chronograph of the aforementioned type showing voltage, the opposite of current ( / I), and the output of the phase comparator (¢) when the current lags behind the voltage;

[0028] [Fig.8] is a chronograph of the aforementioned type showing the voltage, the opposite of the current ( / I), and the output of the phase comparator (¢) when the current is leading the voltage;

[0029] [Fig.9] is a partial view of the circuit of the transmission device according to the invention, showing more particularly the power signal frequency control circuit according to a second embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION

[0030] With reference to [Fig. 1], the transmission device according to the invention comprises a first circuit 100, a second circuit 200, and a cable 300 providing a link between the first circuit 100 and the second circuit 200. According to a typical application In the invention, the first circuit 100 is arranged to be connected to a first electronic device, for example, a data processing unit, and the second circuit 200 is arranged to be connected to a second electronic device, for example, a detector providing measurement data for any physical parameter or a data concentrator connected to one or more detectors. The invention is particularly applicable in an aircraft A comprising a data processing unit A1 connected to the first circuit 100 of the device according to the invention and at least one data concentrator or sensor A2 connected to the second circuit 200 of this device.

[0031] The cable 300, here referred to as "QUADRAX", is standard and comprises a first pair 301 of electrical conductors and a second pair 302 of electrical conductors. In a manner known per se, the pairs are twisted and arranged in quadrature within a shield 303.

[0032] The first circuit comprises an input 101 for the data to be transmitted, an output 102 for the received data, and a power supply 103 receiving a continuous power input signal provided, for example, by the first device or a power distribution network. The continuous power signal is here the Vcc signal, as will be seen later.

[0033] The input 101 is connected to the terminals of a primary winding 104.1 of a first transformer 104 having a secondary winding 104.2 to the terminals of which are connected the electrical conductors of the first pair 301 of the cable 300.

[0034] The output 102 is connected to the terminals of a secondary winding 105.2 of a second transformer 105 having a primary winding 105.1 to the terminals of which are connected the electrical conductors of the second pair 302 of the cable 300.

[0035] The power supply 103 is connected to the terminals of a primary winding 106.1 of a third transformer 106, or power transformer, having a secondary winding 106.2 with a first terminal connected to the midpoint of the secondary winding 104.2, a second terminal connected to the midpoint of the primary winding 105.1, and a midpoint connected to the mechanical ground of the first circuit 100 and / or the first device and to the shield 303 of the cable 300 (this mechanical ground constitutes the potential reference for the first device and the first circuit 100). The power supply 103 includes a DC / AC converter arranged to convert the input DC power signal into a sinusoidal AC power signal having a frequency on the order of megahertz and more particularly equal here to 1 MHz.

[0036] The second circuit includes an output 201 of the data received from the first device, an input 202 of the data to be transmitted to the first device, and a power supply 203 providing a continuous output power signal to the second device.

[0037] The output 201 is connected to the terminals of a secondary winding 204.2 of a first transformer 204 having a primary winding 204.1 to the terminals of which are connected the electrical conductors of the first pair 301 of the cable 300. A Tx line is thus formed between the input 101 and the output 201.

[0038] The input 202 is connected to the terminals of a primary winding 205.1 of a second transformer 205 having a secondary winding 205.2 to the terminals of which are connected the electrical conductors of the second pair 302 of the cable 300. A line Rx is thus formed between the input 202 and the output 102.

[0039] The power supply 203 is connected to the terminals of a secondary winding 206.2 of a third transformer 206 having a primary winding 206.1 having a first terminal connected to the midpoint of the primary winding 204.1, a second terminal connected to the midpoint of the secondary winding 205.2, and a midpoint connected to the mechanical ground of the second circuit 200 and / or the second device and to the shield 303 of the cable 300 (this mechanical ground constitutes the potential reference for the second device and the second circuit 200) via a capacitor 213.1 and a resistor 213.2. The power supply 203 includes an AC / DC converter arranged to convert the received alternating power signal into a direct current output power signal suitable for supplying the second device which forms the powered load.

[0040] It is understood that this provides a complete galvanic isolation solution, for both direct current and high-frequency alternating current, which protects the second device from overvoltage and / or massive current injection (lightning and BCI). Therefore, it is not necessary to use protective components, such as surge suppressors, which are difficult to monitor both during manufacturing and operation.

[0041] The data transmission part is carried out in a conventional manner and will not be described further here. Therefore, the following description focuses solely on the power part.

[0042] The power supply 103 preferably comprises a sinusoidal voltage generator having a frequency of about 1 MHz and an angular phase shift (cosine PHI) equal to 1. This sinusoidal voltage generator is arranged to transmit each of its phases in common mode on the pair of electrical conductors 301 of the Tx line and on the pair of electrical conductors 302 of the Rx line respectively.

[0043] The connection of the primary winding 105.1 and the secondary winding 104.2 to the secondary winding 106.2 will be detailed. The center tap of the primary transformer 105.1 is connected to a first terminal of a first capacitor 107.1, which has a second terminal connected to the center tap of the secondary transformer 104.2. The secondary winding 106.2 has a first terminal connected to the first terminal Capacitor 107.1 is connected by a first line 108.1 and a second terminal connected to the second terminal of the capacitor by a second line 108.2. The first line 108.1 comprises two coils 109.1 in series that are biased in the same direction, and the second line 108.2 comprises two coils 109.2 in series that are biased oppositely to the coils 109.1. Each coil 109.1, 109.2 therefore has its own inductance, and each pair of coils 109.1, 109.2 opposite each other has a mutual inductance. A second capacitor 107.2 extends between the point where the coils 109.1 are connected to each other and the point where the coils 109.2 are connected to each other. The midpoint of the secondary winding 106.2 is connected to the mechanical ground M-Gnd via a third capacitor 107.3 and a resistor 107.4 to achieve a common-mode line matching.This forms a low-loss, fourth-order LC low-pass filter due to the absence of a resistive component, ensuring the elimination of the high-frequency components of the sinusoidal signal which is transmitted with each potential in the common mode of one of the pairs 301, 302 and with the DC component in common mode.

[0044] The second circuit 200, according to a first embodiment, will be described in relation to [Fig.2].

[0045] The first stage comprises a filter 207 and a rectifier bridge 208. The filter 207 is a Pi LC filter comprising a pair of inductors 2071, 2072, with opposite polarities and facing each other, each having its own inductance and together a mutual inductance, each having a first terminal connected to one of the terminals of the secondary winding 206.2 and a second terminal connected to one of the input terminals of the rectifier bridge 208. A first capacitor 2073 connects the first terminals of the inductors 2071, 2072 together, and a second capacitor 2074 connects the second terminals of the inductors 2071, 2072 together. The rectifier bridge 208 is here a full-wave rectifier bridge of the conventional type, in this case of the Graetz type. Filter 207 is an analog circuit that provides pre-filtering to attenuate switching noise from rectifier bridge 208.It is understood that the first stage ensures the conversion of the alternating power signal into a direct power signal having a full-wave rectified voltage equal to the average of the sinusoidal voltage.

[0046] The second stage is arranged to form a current consumer 209 that follows the rectified voltage and comprises a first line 209.1 and a second line 209.2, each extending from one of the output terminals of the rectifier bridge 208 to one of the input terminals of the third stage. The second line comprises, in series, a resistor 2091 and an NPN transistor 2092, having an emitter connected to the resistor 2091 and a collector connected, as previously described, to one of the input terminals of the third stage. The second stage also comprises a Operational amplifier 2090 has a positive input connected to a voltage divider 2093 linking lines 209.1 and 209.2, a negative input connected to the second line 209.2 between resistor 2091 and transistor 2092, a positive supply pin connected to the cathode of a diode 2094 having an anode connected to the first line 209.1, a negative supply pin connected to the second line 209.2, and an output connected via a resistor 2095 to a base of transistor 2092. A capacitor 2096 further connects the cathode of diode 2094 to the second line 209.2. The second stage constitutes an electronic load that simulates resistive load behavior by forming a current-controlled load that follows the waveform of the full-wave rectified voltage. The second stage thus allows cable 300 to "see" a constant load.

[0047] The third stage comprises a Pi LC filter 210 analogous to filter 207. Filter 210 comprises a pair of inductors 2101, 2102, with opposite polarities and facing each other, each having its own inductance and together a mutual inductance. The first inductor 2101 has a first terminal connected to the first line 209.1 of the second stage and a second terminal connected to a first line 211.1 of the fourth stage. The second inductor 2102 has a first terminal connected to the second line 209.2 of the second stage and a second terminal connected to a second line 211.2 of the fourth stage. A first capacitor 2103 connects the first terminals of coils 2101, 2102 together and a second capacitor 2104 connects the second terminals of coils 2101, 2102 together. It is understood that the filter 210 allows the resulting average voltage to be extracted.

[0048] The fourth stage forms a load proportional to the rectified voltage received at the input and therefore a current consumer controlled by the received DC voltage to provide a constant voltage to the second device (i.e., the load user). The fourth stage includes a current generator 211 analogous to the current consumer 209. The first line 211.1 and the second line 211.2 are connected, opposite the third stage, to a voltage regulator 212 which includes in parallel a Zener diode 2121 and a capacitor 2122 and which is connected to the second device. The second line 211.2 includes in series a resistor 2111 and an NPN transistor 2112, having an emitter connected to the resistor 2111 and a collector connected as previously described to the voltage regulator 212. The fourth stage also includes an operational amplifier 2110 having a positive input connected to a voltage divider 2113 connecting lines 211.1 and 211.2, a negative input connected to the second line 211.2 between the resistor 2111 and the transistor 2112, a positive supply pin connected to the cathode of a diode 2114 having an anode connected to the first line 211.1, a negative supply pin connected to the second line 211.2, and an output connected via a resistor 2115 to a base. of transistor 2112. A capacitor 2116 also connects the cathode of diode 2114 to the second line 211.2. The voltage regulator 212 makes the device less sensitive to load variations. The current drawn therefore varies only slightly, depending on the variation in the input voltage. This current flows through the equivalent of a Zener diode, across which a constant voltage is found regardless of the current flowing through it.

[0049] The second circuit therefore draws a voltage similar to the reference voltage to maintain a constant load "seen" by the cable. For example, the cable is loaded by the second circuit to a true resistance of 100 ohms (i=u / r). It is understood that the rectified voltage, equal to the average of the sinusoidal voltage received at the input, serves as the reference voltage for the current generators.

[0050] Preferably, the transformers and coupled inductors are manufactured using PCB technology, i.e., by embedding the cores in the PCB boards and constructing the coils using conductive traces, because this technology guarantees reproducible electrical performance and symmetries such that common-mode rejection is greatly improved. This technology is, for example, described in documents FR-A-2201553 and FR-A-3110780.

[0051] In the variant of [Fig.3], the voltage regulator 212 is replaced by a low dropout linear voltage regulator or LDO also connected to ground.

[0052] The LDO voltage regulator is an analog "series" voltage regulator capable of operating with a very low voltage drop between its input and output. Furthermore, it provides a more precise output voltage, and it is often easier to adjust the output voltage simply by changing the values ​​of resistors not shown in the figure.

[0053] It is then possible to use in the first stage a third-order (and no longer fourth-order) LC low-pass filter 207 because its role is just to limit the reinjection of the switching noise of the diodes of the rectifier bridge 208 into the cable 300.

[0054] The second circuit 200, according to a second embodiment, will be described in relation to [Fig. 4]. The second circuit 200 also comprises four stages. The first and second stages are identical to those of the variant above.

[0055] The second circuit 200 according to the second embodiment differs from the variant of the first embodiment firstly in that the windings 204.2, 206.2 and 205.1 have midpoints connected via capacitors 2041, 2061 and 2051 to the mechanical ground Sensor housing-Gnd of the second circuit 200 and of the second device.

[0056] The second circuit 200 according to the second embodiment differs from the variant of the first embodiment secondly in that the current generator 211 is omitted and replaced by a voltage recovery circuit 220. The voltage recovery circuit 220 comprises a diode 2201 having an anode connected to the first line 209.1 and to the collector of the NPN transistor 2092 and a cathode connected to the voltage regulator LDO. The voltage recovery circuit 220 also comprises a capacitor 2202 having a first terminal connected to the cathode of diode 2021 and to a first branch of the voltage regulator LDO and a second terminal connected to a second branch of the voltage regulator LDO and to ground.

[0057] The diode 2021, capacitor 2022, and LDO voltage regulator assembly forms a variable load stage to supply a constant voltage to the second device. The current consumption is variable such that the sum of the current at the emitter of transistor 2092 and the second branch of the LDO is the same as at the positive input of amplifier 2090. Transistor 2092 acts as an adjustment variable for the current consumption of the second circuit 200, provided that no voltage is present at the negative input of amplifier 2090. It should be noted that the current consumption through diode 2093 is very low, which has very little influence on the overall current consumption of the second circuit 200.

[0058] Electromagnetic compatibility with respect to massive current injections resulting from high-frequency radar-type pulses that produce common-mode disturbances is achieved by the symmetry of the lines, the connection to the mechanical ground, and the differential connection of the dual inductor. The capacitor 2061 further dissipates common-mode disturbances.

[0059] The four-pole common-mode inductance of coils 2071 and 2072 is applied to the entire four-wire line to present a high impedance to high-frequency common-mode parasitic signals. Transformers 204, 205, and 206 provide DC and low-frequency isolation. At series resonance of this assembly (around 100 MHz), the system being highly symmetrical due to PCB technology, the currents are balanced, opposite, and flow almost entirely to the shield 303 of cable 300 via resistor 213.2. The value of the resistance 213.2 is equal to the characteristic impedance value of the cable 300 in common mode, between 50 and 100 ohms, in order to avoid creating standing waves which could increase common mode currents or voltages in certain parts of the cable, and thus create disturbances on useful signals by poor common mode rejection.

[0060] The residual common-mode voltages are all transmitted to the equipotential bonding of the mechanical ground, which is itself connected to the structure near the carrier. Thus, lightning and BCI currents cannot create differential voltages. dangerous for the electronics of this sensor. Therefore, capacitors 2041, 2051, and 2061 exhibit low impedance with respect to the high-frequency common-mode voltages exacerbated during the resonance of the series LC pairs formed by: - the common mode inductance of coils 2071 and 2072 and transformer 204; - the common mode inductance of coils 2071 and 2072 and transformer 205; - the common mode inductance of coils 2071 and 2072 and transformer 206.

[0061] Thus, the high-frequency currents are mainly fed back to the proximity potential reference of the second device. This results in a high-frequency common-mode voltage, applied to the electronics of the second device, which is completely minimized and therefore has no effect on the operation of the second device.

[0062] In all these embodiments, the invention provides a number of provisions aimed at promoting the efficiency of the power supplied by the power supply 103.

[0063] According to a first arrangement, a capacitor 110 (visible in figures 1, 5 and 9) is mounted in parallel with the primary winding 106.1 of the transformer 106. The capacitor 110 is sized to provide overall compensation of the reactive current to the transformer 106, line 300, circuit 200 and load formed by the second electronic device.

[0064] According to a second arrangement, the primary winding 106.1 of the third transformer 106 is connected to a servo circuit 400 to control the frequency of the power signal to a cancellation of a voltage / current phase shift of the power signal.

[0065] It is understood that the transformer 106 associated with the capacitor 110 behaves like a parallel LC resonant circuit with a resonant frequency. At the resonant frequency, the sinusoidal current and the sinusoidal voltage are exactly in phase. Below the resonant frequency, the current lags behind the voltage, and above the resonant frequency, the current leads the voltage. The invention makes it possible to control the frequency of the supply voltage based on the cancellation of the phase shift between the current and the voltage.

[0066] The first embodiment of the servo circuit 400 provided for this purpose, illustrated in [Fig.5], is analog.

[0067] The servo circuit 400 includes a phase comparator 410 having a first input connected to a first terminal of the LC circuit, a second input connected to a second terminal of the LC circuit and an output connected to a 420 error integrator / amplifier.

[0068] The phase comparator 410 is arranged to compare the phase of the current with the phase of the voltage and produce at the output a voltage representative of the phase difference. At the output of the phase comparator 410, the average voltage is Vcc / 2 (50% duty cycle, Vcc being the supply voltage of the logic circuits) when the power factor is equal to 1 (which is equivalent to a zero phase shift between the voltage and the current).

[0069] This average voltage is subtracted in the error integrator / amplifier 420 from a reference voltage equal to Vcc / 2 (implemented by a voltage divider formed in a manner known in itself by the resistors 421). The error integrator / amplifier 420 (with pseudo-infinite gain) integrates the resulting difference. In this way, a proportional-integral type control is achieved. It should be noted that a large bandwidth is not required for this control loop because the aim is to compensate for initial and thermal drifts of passive components, i.e., very slow drifts.

[0070] It is understood that the resulting average component of this treatment is a DC voltage whose amplitude and sign depend on the current / voltage phase shift: - when the current leads the voltage, the average resultant is greater than Vcc / 2; - when the current lags behind the voltage, the average resultant is less than Vcc / 2; - when the current is in phase with the voltage, the average resultant is equal to Vcc / 2.

[0071] The error integrator / amplifier 420 has an output connected to a control input of a voltage-controlled oscillator or VCO 430. The output voltage of the error integrator / amplifier 420 controls the output frequency of the time base of the VCO 430, which produces an output square wave signal that is very rich in odd harmonics and has a mid-range component equal to half the supply voltage of the VCO 430. This mid-range component is eliminated by a high-pass filter, and the odd harmonics of the square wave signal are attenuated by a second-order low-pass filter. A higher-order filter is possible if greater spectral purity is required.

[0072] The output of the VCO 430 is connected to a control input of the power supply 103 which includes a class D power amplifier 440 having transistors driven according to the square signal supplied at the output of the VCO 430 to provide the sinusoidal power signal.

[0073] The servo circuit will now be detailed.

[0074] In the phase comparator 410, the sinusoidal voltage passes through an amplifier 411 and is compared to "zero volts" by a comparator 412, which provides an output "on / off" signal representing exactly the sign of the sinusoidal voltage (positive or negative). This signal will serve as the phase reference for the sinusoidal voltage.

[0075] Still within the phase comparator 410, the sinusoidal current, measured across a shunt resistor 405, passes through an amplifier 413 and is compared to "zero volts" by a comparator 414. This comparator provides an output signal that accurately represents the phase of the sinusoidal current (positive or negative). The sinusoidal signal oscillates around the 0-volt potential reference (or "ground"), and the comparator 414 generates a logic output of 1 if the input voltage is greater than 0V, or 0 if it is less than 0V. At the output of this comparator 414, we find a logic signal oscillating between 0 and 1: a square wave with a frequency and phase equal to that of the sinusoidal source. This square wave can be said to represent the phase of the sinusoidal signal and serves as the phase reference for the sinusoidal current.The opposite value of the current phase is obtained by placing a 415 logic inverter to compare the current / voltage signals which are in opposite phase (180° out of phase).

[0076] The current phase reference signal and the voltage phase reference signal are compared to each other by the equivalent of an RS-416 flip-flop sensitive to the rising edges (and not to the logic states) of the signals to be compared. The signal resulting from this comparison, when the current and voltage are in phase, has a duty cycle of 50%.

[0077] This logic signal with a 50% duty cycle and an amplitude between 0 and Vcc is applied to the error integrator / amplifier 420, which is referenced to the voltage Vcc / 2. The error amplifier 420 amplifies the difference with a very high static gain (on the order of 10⁷). This very high gain results in a minimized phase error, which in practice is only related to the relative equality between the two resistors 421 of the voltage divider.

[0078] The average value is integrated with a very large time constant, on the order of 1 to 10 seconds, a high value because we only seek to compensate for very slow drifts as mentioned previously.

[0079] The output voltage of the error integrator / amplifier 420 drives the frequency supplied by the VCO 430. The latter exists directly in monolithic form but can be implemented from discrete components. This type of circuit is well known and will not be detailed here.

[0080] The output signal from the VCO 430 controls a standard driver component 441 dedicated to the interface of the MOS-type power transistors 442 of the amplifier The 440 class D power transistor acts as an inverter. Note that, for lower power applications, it is possible to eliminate the standard driver component and directly drive a push-pull stage of complementary transistors, powered by the Vcc voltage common to all the logic circuitry. The 442 power transistors operate in on / off mode (open or closed) to minimize their Joule heating losses.

[0081] The output signal of the Class D power amplifier 440 is rich in odd harmonics with a decay ratio equal to that of the harmonic's order. In order to limit the amplitude of these 3rd, 5th, 7th, and higher harmonic voltages, a filter 450 is provided, comprising an inductor 451 in series with the power stage. Its impedance is proportional to the frequency (Lco). The filter 450 also includes a capacitor 452 in series to eliminate the DC component.

[0082] Figure 7 shows that, for a current in phase with the voltage, the output " <e>» has a duty cycle of 50%, therefore an average voltage of Vcc / 2.

[0083] In the event of a phase shift of the current with respect to the voltage, in either direction, we find average components greater than the voltage Vcc / 2 or less than the voltage Vcc / 2, depending on the direction of the phase shift. These two cases are illustrated in Figures 8 and 9.

[0084] This provides an automatic power factor compensation solution by automatically adjusting the supply frequency to the resonant frequency of the equivalent circuit of the transmission line.

[0085] It is also possible to implement the control circuit in digital form, as shown in [Fig.9].

[0086] This second embodiment is identical to the first embodiment except that the integrator / amplifier 420 and the VCO 430 have been replaced by their digital equivalents 420' and 430'.

[0087] Thus, the error amplification and integration function is performed by a digital counter 420' incremented by a high-frequency clock 460 (typically 100 MHz). The control from the phase comparator 410 gives the count or count-down command (U / D signal, as "up" for counting and "down" for counting) according to the phase lag or lead of the current relative to the voltage. The resulting output is a numerical value whose amplitude describes the phase error. This numerical value is applied to the input of a digitally controlled oscillator or NCO 430'.

[0088] The NCO 430' thus forms a time base driven by the phase error. The output frequency of the NCO 430', and ultimately its phase, is a function of the phase error between the current and the supply voltage of the line.

[0089] The control of the class D 440 power amplifier is carried out as before.

[0090] This digital solution is advantageous because of the miniaturization it allows and the reproducibility of the results. All the digital components described above can be integrated into a programmable digital component (for example, an FPGA).

[0091] It should be noted that the temporal resolution of the digital system is not perfect and is conditioned by the maximum permissible frequency for the time base (typically 100 MHz here). This results in perpetual adjustments around the center frequency of the signal on the line (typically 1 MHz), which in practice generates phase noise. Conversely, this can prove to be an advantage for electromagnetic compatibility due to the spectral spreading of the spectral line corresponding to the frequency of the supply voltage transmitted on the line.

[0092] 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.

[0093] In particular, any sinusoidal signal generator can be used as a current generator. The sinusoidal signal generator can further be arranged to provide a signal having a frequency other than 1 MHz.

[0094] The described structure is particularly simple. Indeed, the received sinusoidal signal must be loaded by a "real" resistance equal to the characteristic impedance of the line (around one hundred ohms in the case of the Quadrax cable), and the power to be transmitted is low, on the order of a watt: to keep the system as simple as possible, a purely analog solution is preferred here, despite its low efficiency. However, a solution based on digital components could be considered.

[0095] This solution is also advantageous because many of the components that can be used to implement it are readily available commercially.

[0096] The use of a control circuit is optional; mounting a capacitor in parallel with the primary winding of the power transformer provides sufficient efficiency improvement in certain applications.

[0097] The invention is applicable to any type of installation, fixed or mobile, and to any vehicle.< / e> < / t>

Claims

Demands

1. Power and data transmission device, comprising a first circuit (100), a second circuit (200) and a cable (300) connecting the first circuit and the second circuit and having a first pair (301) and a second pair (302) of electrical conductors for transmitting a data signal and a power signal, the data signal being transmitted in differential mode in a first direction on the first pair of electrical conductors and in a second direction on the second pair of electrical conductors;characterized in that the first circuit is arranged to emit in differential mode the power signal on a sinusoidal carrier using the common modes of the two pairs of conductors and the second circuit is arranged to receive said power signal by maintaining with respect to the cable a real impedance equal to an iterative impedance of the cable, in that the first circuit (100) comprises a first transformer (104) connected to the first pair (301) of electrical conductors, a second transformer (105) connected to the second pair (302) of electrical conductors, and a third transformer (106) in common mode on the two pairs of electrical conductors, and in that a capacitor (110) is placed in parallel with a primary winding (106.1) of the third transformer (106).;

2. Device according to claim 1, wherein the primary winding (106.1) of the third transformer (106) is connected to a servo circuit (400) arranged to servo a frequency of the power signal to a cancellation of a voltage / current phase shift of the power signal.

3. Device according to claim 2, wherein the control circuit (400) includes a phase comparator (410) arranged to compare the phase of the current with the phase of the voltage and produce at the output a voltage representative of a phase difference.

4. A device according to claim 3, wherein the phase comparator (410) comprises a voltage amplifier (411) and a voltage comparator (412) for providing at output a sinusoidal voltage phase reference signal, a current amplifier (413) and a current comparator (414) for providing in output a sinusoidal current phase reference signal, a rising edge sensitive logic flip-flop to compare the sinusoidal voltage phase reference signal and the sinusoidal current phase reference signal in opposite phase and obtain an output signal having a duty cycle.

5. Device according to claim 4, wherein the control circuit (400) comprises an error integrator / amplifier (420) receiving as input the output signal from the phase comparator (410) and a reference voltage and having an output connected to a voltage-controlled oscillator (430) controlling a class D power amplifier (440) having an output providing the power signal.

6. Device according to claim 4, wherein the control circuit (400) comprises a digital counter (420') receiving as input the output signal from the phase comparator (410) and a clock signal and having an output connected to an oscillator controlled by a digital input (430) controlling a class D power amplifier (440) having an output providing the power signal.

7. Device according to claim 5 or 6, wherein the output of the class D power amplifier (440) is connected to a filter (450) arranged to attenuate odd harmonics and a DC component of the power signal.

8. Device according to any one of the preceding claims, wherein the first circuit (100) is arranged so that the power signal has an alternating voltage having a high frequency, preferably on the order of megahertz.

9. Device according to any one of the preceding claims, wherein the second circuit (200) comprises: - an AC / DC converter (208) receiving the power signal as input and providing a DC power signal as output having a rectified voltage; - an electronic load arranged to be proportional to the rectified voltage.

10. Device according to claim 9, wherein the AC / DC converter (208) is associated with a filter (207) arranged to

11.

12.

13.

14. to reduce switching noise from the AC / DC converter. Device according to claim 10, wherein the filter (207) comprises a common-mode mutual inductance (2071, 2072). Device according to any one of claims 9 to 11, wherein the electronic load comprises a current consumer (209) that follows the rectified voltage and is connected to the output of the AC / DC converter (208). Device according to claim 12, comprising a low-pass filter (210) Pi disposed at the output of the current consumer (209) and matched to the iterative impedance of the cable (300). Aircraft comprising a data processing device connected to the first circuit (100) of a device according to any one of the preceding claims and at least one sensor connected to the second circuit (200) of this device.

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