EP3830804B1 - Wireless sensor node - Google Patents

Wireless sensor node Download PDF

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Publication number
EP3830804B1
EP3830804B1 EP18785850.1A EP18785850A EP3830804B1 EP 3830804 B1 EP3830804 B1 EP 3830804B1 EP 18785850 A EP18785850 A EP 18785850A EP 3830804 B1 EP3830804 B1 EP 3830804B1
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Prior art keywords
signal
radio
sensor node
unit
sensor
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German (de)
French (fr)
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EP3830804A1 (en
Inventor
Christoph Armschat
Uwe WEIGT
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Siemens Energy Global GmbH and Co KG
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Siemens Energy Global GmbH and Co KG
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    • G—PHYSICS
    • G08—SIGNALLING
    • G08C—TRANSMISSION SYSTEMS FOR MEASURED VALUES, CONTROL OR SIMILAR SIGNALS
    • G08C13/00—Arrangements for influencing the relationship between signals at input and output, e.g. differentiating, delaying

Definitions

  • the invention relates to a wireless sensor node.
  • a wireless sensor node transmits measurement data recorded by a sensor to a receiver wirelessly using radio waves.
  • Wireless sensor nodes are often placed in hard-to-reach or dangerous locations where wiring, replacement and/or maintenance of the sensor is not possible or very expensive. For this reason, special requirements are usually placed on a wireless sensor node in terms of its robustness, longevity, wireless range and self-sufficient energy supply. These requirements often make it difficult to design a wireless sensor node in a small size in particular. Furthermore, the energy supply often proves to be problematic. On the one hand, batteries enable a self-sufficient energy supply, but on the other hand they only have a limited service life. However, replacing a battery is often difficult or impossible, especially with wireless sensor nodes. Economical power consumption can increase the lifespan of a battery, but on the other hand it requires compromises in the transmission power and/or the operating times of the wireless sensor node.
  • the device has an energy converter (such as a solar converter, a vibration converter, a thermal converter or the like). Energy stores are charged with the energy converted into electrical energy.
  • the device is preferably the size of a standard battery so that a conventional battery can be replaced with this device.
  • the patent application U.S. 2010/0264906 A1 discloses an apparatus for measuring electrical power at a circuit breaker.
  • This device has a current transformer placed on an electrical line leading to the circuit breaker.
  • the current supplied by the current transformer is used on the one hand to determine the electrical power and on the other hand to supply the device with energy.
  • the invention is based on the object of specifying an improved wireless sensor node and a method for operating it, in particular for use in an electromagnetically highly loaded environment.
  • the object is achieved according to the invention by a radio sensor node having the features of claim 1 and a method having the features of claim 14 .
  • a radio sensor node comprises a sensor unit for detecting a measured variable and outputting an analog electrical sensor signal, an energy harvesting unit for harvesting energy from the sensor signal, a signal processing unit for generating a transmission signal from the sensor signal and a radio unit for sending the transmission signal as a radio signal.
  • the sensor signal can be fed alternately to the energy harvesting unit and the signal processing unit.
  • the invention therefore provides for using the electrical sensor signal of the sensor unit of a wireless sensor node to supply energy to the wireless sensor node.
  • the radio sensor node has an energy harvesting unit for harvesting energy (in particular electrical energy), the so-called energy harvesting, from the sensor signal.
  • the invention provides for the sensor signal to be fed alternately to the signal processing unit for generating a transmission signal from the sensor signal and to the energy harvesting unit for harvesting energy.
  • the invention exploits that a wireless sensor node usually does not constantly process a sensor signal and send it as a radio signal, but is in sleep mode most of the time to save energy. According to the invention, this sleep mode is used to harvest energy from the sensor signal.
  • the energy harvesting unit can in particular also be referred to as an energy generation unit.
  • the energy harvesting unit can therefore also be referred to as an energy generation unit for obtaining electrical energy from the sensor signal; the energy harvesting unit serves to obtain energy from the sensor signal. This is in particular electrical energy.
  • the invention provides that the signal processing unit has an averaging circuit for generating the transmission signal as an average of the sensor signal rectified with a rectifier circuit.
  • a complex evaluation of the sensor signal in the radio sensor node is dispensed with and instead only an average value of the rectified sensor signal is generated as the transmission signal.
  • this generation of a transmission signal is particularly energy-saving.
  • the energy-intensive evaluation of the transmission signal is carried out by a user of the wireless sensor node.
  • a calibration curve is measured, for example, in a test facility belonging to the manufacturer of the radio sensor node, which curve represents the transmission signal as a function of the measured variable and is made available to a user of the radio sensor node.
  • the invention provides that an effective value of the sensor signal is alternatively generated by the signal processing unit as the transmission signal.
  • This embodiment of the invention which is an alternative to the aforementioned embodiment, is preferably used when the radio sensor node has sufficient energy available to calculate the effective value due to energy harvesting.
  • the radio sensor node has a signal input, to which the sensor signal is fed, and switching logic, by means of which the signal input can be connected alternately to the energy harvesting unit and the signal processing unit.
  • This refinement of the invention implements the alternating supply of the sensor signal to the signal processing unit and the energy harvesting unit by means of switching logic which alternately connects the signal input to the signal processing unit and the energy harvesting unit.
  • a further embodiment of the invention provides a voltage limiting unit to protect the signal input against overvoltages.
  • This refinement of the invention advantageously increases the robustness of the signal input against surge voltages. These can be caused by direct couplings or by inductive couplings (e.g. from current surges in nearby current paths) or by capacitive couplings, which can occur particularly in the vicinity of high-voltage systems.
  • a further embodiment of the invention provides that the signal input has contacts led out of a sensor node housing of the wireless sensor node. This enables contacting of the signal input from the outside. Furthermore, one of the contacts can be used to ground the contact outside of the radio sensor node.
  • a further embodiment of the invention provides that the radio sensor node has a sensor node housing cast in a plastic with low permittivity. As a result, the radio signals of the radio unit are advantageously hardly attenuated by the sensor node housing.
  • the radio unit has an antenna, for example a ring antenna with one or more windings, and is designed for this purpose is to alternately send the radio signal with the antenna and to inductively harvest energy from a magnetic field present in an area surrounding the radio sensor node and/or to detect a magnetic field strength of a magnetic field present in an area surrounding the radio sensor node.
  • These refinements of the invention therefore provide for using the antenna of the wireless sensor node not only for sending wireless signals, but also for harvesting energy from a magnetic field and/or for detecting a magnetic field strength of a magnetic field in the vicinity of the wireless sensor node.
  • the antenna is advantageously also used to supply energy to the wireless sensor node and/or as a magnetic field sensor.
  • a further embodiment of the invention provides that the radio sensor node is arranged on an electrically conductive surface and has a ground connection that is electrically connected to the electrically conductive surface.
  • the wireless sensor node may include an electromagnetic shield connected to the electrically conductive surface. This refinement of the invention uses an electrically conductive surface, on which the radio sensor node is arranged, for the potential connection of the radio sensor node and an electromagnetic shielding of the radio sensor node.
  • the radio sensor node has an energy storage unit for storing energy.
  • the energy storage unit has, for example, a supercapacitor and/or an accumulator.
  • the energy storage unit includes a supercapacitor and an accumulator, the accumulator is charged only when the supercapacitor is charged to a nominal voltage.
  • supercapacitors have longer lifetimes than accumulators, so that the supercapacitor can still be used for a long time after the battery life has expired.
  • the accumulator is only charged after the supercapacitor has been charged to a nominal voltage. This is achieved by a decoupling circuit. If the accumulator becomes defective after a few years of operation, it no longer builds up any voltage. The decoupling circuit then prevents the supercapacitor from being discharged by the defective accumulator, so that the radio sensor node can continue to be supplied with energy from the supercapacitor.
  • the parallel installation of the supercapacitor and the accumulator has the advantage that - depending on the energy harvest and cycle times - significantly more measurement and calculation tasks can be processed in the first years of use of the wireless sensor node than with the sole supply from the supercapacitor.
  • the measured variable is accordingly recorded with the sensor unit and the sensor signal is output, the sensor signal is fed alternately to the energy harvesting unit and the signal processing unit, the transmission signal is generated from the sensor signal with the signal processing unit, the transmission signal is processed with the radio unit sent as a radio signal and the energy harvesting unit harvests energy from the sensor signal.
  • FIG 1 shows a block diagram of an embodiment of a radio sensor node 1 according to the invention.
  • the radio sensor node 1 comprises a sensor node housing 3, a sensor unit 5, a signal input 7, a switching logic 9, a signal processing unit 11, an energy harvesting unit 13 with an energy storage unit 15, a radio unit 17 and an electromagnetic shield 19 .
  • a measured variable is detected with the sensor unit 5 and an analog electrical sensor signal S representing the measured variable is output to the signal input 7 .
  • the sensor unit 5 has, for example, a temperature sensor for detecting a temperature as a measured variable, but can also have a sensor for detecting another measured variable.
  • the sensor signal S is an electrical voltage generated by the sensor unit 5, for example a voltage in the single-digit volt range.
  • the switching logic 9 connects the signal input 7 alternately to the signal processing unit 11 and the energy harvesting unit 13 and thus supplies the sensor signal S to the signal processing unit 11 and the energy harvesting unit 13 alternately.
  • the switching logic 9 has, for this purpose, low-loss semiconductor switches, for example metal-oxide-semiconductor field effect transistors (MOSFET), and a control unit for driving the semiconductor switches.
  • MOSFET metal-oxide-semiconductor field effect transistors
  • the signal processing unit 11 generates a transmission signal T from the sensor signal S.
  • the signal processing unit 11 generates a mean value of the rectified sensor signal S as the transmission signal T, cf figure 2 .
  • figure 2 1 shows a circuit diagram of a rectifier circuit 21 and an averaging circuit 23 for generating the transmission signal T as an average value of the rectified sensor signal S.
  • the rectifier circuit 21 is designed as a bridge rectifier circuit formed by four diodes 25.
  • the averaging circuit 23 is connected downstream of the rectifier circuit 21 and has an inductor 27 , an averaging capacitor 29 and an averaging resistor 31 connected in parallel with the averaging capacitor 29 .
  • the signal input 7 is connected to the signal processing unit 11 via the switching logic 9, the switching logic 9 in figure 2 is not shown.
  • the signal input 7 is protected against overvoltages by a voltage limiting unit 33 formed by a varistor.
  • the voltage limiting unit 33 is designed to limit an incoming voltage surge that decays over 5 ms and has a voltage peak of 100 V to 15 V to 20 V.
  • the transmission signal T is a voltage present at the parallel connection of the averaging capacitor 29 and the averaging resistor 31 .
  • a calibration curve is measured in a test facility of the manufacturer of the radio sensor node 1, which represents the transmission signal T as a transmission function of the measured variable and is made available to a user of the radio sensor node 1.
  • a typical time course for the measurement signal is selected, which roughly corresponds to the expected measurement variable on the system.
  • the signal processing unit 11 for generating the transmission signal T as a
  • the mean value of the rectified sensor signal S does not require any complex evaluation of the sensor signal S in the radio sensor node 1 and is therefore particularly energy-saving. If sufficient harvested energy is available, the signal processing unit 11 can instead be implemented in a more complex manner.
  • the signal processing unit 11 can have an integrated circuit that calculates an effective value (RMS) of the sensor signal S as the transmission signal T.
  • RMS effective value
  • the effective value is formed over a time period of about 100 ms with a sampling frequency of more than 3 kHz.
  • the measured value processing can also include a number of signals, contain a measured value memory and contain more complex processing.
  • the energy harvesting unit 13 is designed to harvest energy from the sensor signal S, which energy is used to supply the radio sensor node 1 with energy.
  • the energy harvesting unit 13 has an energy storage unit 15 which is designed to store energy when the harvested energy is not currently required to supply the wireless sensor node 1 with energy.
  • FIG figure 3 shows a circuit diagram of an exemplary embodiment of the energy storage unit 15, it being assumed that the energy storage unit 15 is connected to the signal input 7 via the switching logic 9, and as in FIG figure 2 the switching logic 9 is not shown.
  • the energy storage unit 15 of this exemplary embodiment has a supercapacitor 35, an accumulator 37, an overflow unit 39 with integrated overcharge protection and a blocking diode 41 and is connected to the signal input 7 via a rectifier circuit 21, with the rectifier circuit 21 having the in figure 2 shown rectifier circuit 21 match or can be performed separately.
  • the supercapacitor 35 and the accumulator 37 are decoupled by the overflow unit 39, but are in principle connected in parallel to one another.
  • the overflow unit 39 directs excess Energy into the accumulator 37 when the supercapacitor 35 is charged to a nominal voltage, ie the accumulator 37 is charged only when the supercapacitor 35 is already charged to the nominal voltage.
  • the energy storage unit 15 is only operated with the supercapacitor 35 .
  • the radio unit 17 has an antenna 43 with which the transmission signal T is sent as a radio signal.
  • the antenna 43 is designed as a ring antenna with one or more turns.
  • the radio unit 17 is also configured to alternately transmit the radio signal with the antenna 43 and to inductively harvest energy from a magnetic field present in the vicinity of the radio sensor node 1 and/or to detect a magnetic field strength of a magnetic field present in the vicinity of the radio sensor node 1.
  • the electromagnetic shielding 19 is designed as a low-inductance conductor loop, which runs around the electrical and electronic components of the wireless sensor node 1 in order to shield electromagnetic fields in the sensor node housing 3 .
  • the signal input 7 has contacts 44, 45 led out of the sensor node housing 3, via which the signal input 7 can be contacted from the outside.
  • an external sensor unit 5 can be connected to the signal input 7 via the contacts 44 , 45 in order to feed a sensor signal S output by the external sensor unit 5 to the signal input 7 .
  • a contact 45 led out and the electromagnetic shield 19 are connected to a ground connection 47 led out of the sensor node housing 3 .
  • the ground connection 47 is electrically connected to an electrically conductive surface 49 on which the radio sensor node 1 is arranged.
  • the energy harvesting unit 13 can optionally harvest energy via additional contacts 51 , 52 led out of the sensor node housing 3 .
  • the sensor node housing 3 is cast in a plastic with a low permittivity, so that the radio signals from the antenna 43 are hardly attenuated.
  • the radio sensor node 1 is used, for example, in an electromagnetically highly loaded environment.

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Description

Die Erfindung betrifft einen Funksensorknoten.The invention relates to a wireless sensor node.

Ein Funksensorknoten übermittelt mittels eines Sensors erfasste Messdaten drahtlos mittels Funkwellen an einen Empfänger. Funksensorknoten werden häufig an schwer zugänglichen oder gefährlichen Orten angeordnet, an denen eine Verkabelung, ein Austausch und/oder eine Wartung des Sensors nicht möglich oder sehr aufwändig sind. Deshalb werden an einen Funksensorknoten in der Regel besondere Anforderungen hinsichtlich dessen Robustheit, Langlebigkeit, Funkreichweite und autarker Energieversorgung gestellt. Diese Anforderungen erschweren häufig insbesondere die Ausführung eines Funksensorknotens in einer kleinen Baugröße. Ferner erweist sich die Energieversorgung häufig als problematisch. So ermöglichen Batterien einerseits zwar eine autarke Energieversorgung, haben andererseits aber nur eine eingeschränkte Lebensdauer. Gerade bei Funksensorknoten ist ein Austausch einer Batterie jedoch häufig schwierig oder nicht möglich. Ein sparsamer Energieverbrauch kann zwar die Lebensdauer einer Batterie verlängern, andererseits aber Abstriche bei der Sendeleistung und/oder den Betriebszeiten des Funksensorknotens erfordern.A wireless sensor node transmits measurement data recorded by a sensor to a receiver wirelessly using radio waves. Wireless sensor nodes are often placed in hard-to-reach or dangerous locations where wiring, replacement and/or maintenance of the sensor is not possible or very expensive. For this reason, special requirements are usually placed on a wireless sensor node in terms of its robustness, longevity, wireless range and self-sufficient energy supply. These requirements often make it difficult to design a wireless sensor node in a small size in particular. Furthermore, the energy supply often proves to be problematic. On the one hand, batteries enable a self-sufficient energy supply, but on the other hand they only have a limited service life. However, replacing a battery is often difficult or impossible, especially with wireless sensor nodes. Economical power consumption can increase the lifespan of a battery, but on the other hand it requires compromises in the transmission power and/or the operating times of the wireless sensor node.

Aus der Schrift US 2007/0182362 A1 ist ein Gerät zur Energieernte (energy harvesting) und zur Speicherung dieser elektrischen Energie bekannt. Dazu weist das Gerät einen Energiewandler (wie beispielsweise einen Solarwandler, einen Vibrationswandler, einen thermischen Wandler o.ä.) auf. Mit der in elektrische Energie gewandelten Energie werden Energiespeicher aufgeladen. Das Gerät hat vorzugsweise die Größe einer Standard-Batterie, damit eine herkömmliche Batterie durch dieses Gerät ersetzt werden kann.From Scripture U.S. 2007/0182362 A1 a device for energy harvesting (energy harvesting) and for storing this electrical energy is known. For this purpose, the device has an energy converter (such as a solar converter, a vibration converter, a thermal converter or the like). Energy stores are charged with the energy converted into electrical energy. The device is preferably the size of a standard battery so that a conventional battery can be replaced with this device.

Die Patentanmeldung US 2010/0264906 A1 offenbart ein Gerät zur Messung der elektrischen Leistung an einem Leistungsschalter. Dieses Gerät weist einen Stromwandler auf, der an einer zu dem Leistungsschalter führenden elektrischen Leitung platziert ist. Der von dem Stromwandler gelieferte Strom dient zum einen zur Bestimmung der elektrischen Leistung und zum anderen zur Energieversorgung des Geräts.The patent application U.S. 2010/0264906 A1 discloses an apparatus for measuring electrical power at a circuit breaker. This device has a current transformer placed on an electrical line leading to the circuit breaker. The current supplied by the current transformer is used on the one hand to determine the electrical power and on the other hand to supply the device with energy.

Der Erfindung liegt die Aufgabe zugrunde, einen verbesserten Funksensorknoten und ein Verfahren zu dessen Betreiben anzugeben, insbesondere für den Einsatz in einer elektromagnetisch hoch belasteten Umgebung.The invention is based on the object of specifying an improved wireless sensor node and a method for operating it, in particular for use in an electromagnetically highly loaded environment.

Die Aufgabe wird erfindungsgemäß durch einen Funksensorknoten mit den Merkmalen des Anspruchs 1 und ein Verfahren mit den Merkmalen des Anspruchs 14 gelöst.The object is achieved according to the invention by a radio sensor node having the features of claim 1 and a method having the features of claim 14 .

Vorteilhafte Ausgestaltungen der Erfindung sind Gegenstand der Unteransprüche.Advantageous configurations of the invention are the subject matter of the dependent claims.

Ein erfindungsgemäßer Funksensorknoten umfasst eine Sensoreinheit zum Erfassen einer Messgröße und Ausgeben eines analogen elektrischen Sensorsignals, eine Energieernteeinheit zum Ernten von Energie aus dem Sensorsignal, eine Signalverarbeitungseinheit zum Erzeugen eines Übertragungssignals aus dem Sensorsignal und eine Funkeinheit zum Senden des Übertragungssignals als ein Funksignal. Das Sensorsignal ist wechselweise der Energieernteeinheit und der Signalverarbeitungseinheit zuführbar.A radio sensor node according to the invention comprises a sensor unit for detecting a measured variable and outputting an analog electrical sensor signal, an energy harvesting unit for harvesting energy from the sensor signal, a signal processing unit for generating a transmission signal from the sensor signal and a radio unit for sending the transmission signal as a radio signal. The sensor signal can be fed alternately to the energy harvesting unit and the signal processing unit.

Die Erfindung sieht also vor, das elektrische Sensorsignal der Sensoreinheit eines Funksensorknotens zur Energieversorgung des Funksensorknotens zu verwenden. Dazu weist der Funksensorknoten eine Energieernteeinheit zum Ernten von Energie (insbesondere elektrischer Energie), dem so genannten Energy Harvesting, aus dem Sensorsignal auf. Die Erfindung sieht vor, das Sensorsignal wechselweise der Signalverarbeitungseinheit zum Erzeugen eines Übertragungssignals aus dem Sensorsignal und der Energieernteeinheit zum Ernten von Energie zuzuführen. Die Erfindung nutzt aus, dass ein Funksensorknoten in der Regel nicht ständig ein Sensorsignal verarbeitet und als Funksignal sendet, sondern sich die überwiegende Zeit in einem Schlafmodus befindet, um Energie zu sparen. Dieser Schlafmodus wird erfindungsgemäß genutzt, um Energie aus dem Sensorsignal zu ernten. Die Energieernteeinheit kann insbesondere auch als Energiegewinnungseinheit bezeichnet werden. Die Energieernteeinheit kann also auch als Energiegewinnungseinheit zum Gewinnen von elektrischer Energie aus dem Sensorsignal bezeichnet werden; die Energieernteeinheit dient zum Gewinnen von Energie aus dem Sensorsignal. Es handelt sich dabei insbesondere um elektrische Energie.The invention therefore provides for using the electrical sensor signal of the sensor unit of a wireless sensor node to supply energy to the wireless sensor node. For this purpose, the radio sensor node has an energy harvesting unit for harvesting energy (in particular electrical energy), the so-called energy harvesting, from the sensor signal. The invention provides for the sensor signal to be fed alternately to the signal processing unit for generating a transmission signal from the sensor signal and to the energy harvesting unit for harvesting energy. The invention exploits that a wireless sensor node usually does not constantly process a sensor signal and send it as a radio signal, but is in sleep mode most of the time to save energy. According to the invention, this sleep mode is used to harvest energy from the sensor signal. The energy harvesting unit can in particular also be referred to as an energy generation unit. The energy harvesting unit can therefore also be referred to as an energy generation unit for obtaining electrical energy from the sensor signal; the energy harvesting unit serves to obtain energy from the sensor signal. This is in particular electrical energy.

Die Erfindung sieht vor, dass die Signalverarbeitungseinheit eine Mittelungsschaltung zum Erzeugen des Übertragungssignals als ein Mittelwert des mit einer Gleichrichterschaltung gleichgerichteten Sensorsignals aufweist. Bei dieser Ausgestaltung der Erfindung wird auf eine aufwändige Auswertung des Sensorsignals in dem Funksensorknoten verzichtet und stattdessen als Übertragungssignal lediglich ein Mittelwert des gleichgerichteten Sensorsignals erzeugt. Gegenüber einer Auswertung des Sensorsignals in dem Funksensorknoten ist diese Erzeugung eines Übertragungssignals besonders energiesparend. Die energieintensive Auswertung des Übertragungssignals erfolgt in diesem Fall bei einem Benutzer des Funksensorknotens. Zum Auswerten des Übertragungssignals wird beispielsweise in einem Prüffeld des Herstellers des Funksensorknotens eine Kalibrierkurve ausgemessen, die das Übertragungssignal als Funktion der Meßgröße darstellt und einem Benutzer des Funksensorknotens zur Verfügung gestellt wird.The invention provides that the signal processing unit has an averaging circuit for generating the transmission signal as an average of the sensor signal rectified with a rectifier circuit. In this embodiment of the invention, a complex evaluation of the sensor signal in the radio sensor node is dispensed with and instead only an average value of the rectified sensor signal is generated as the transmission signal. Compared to an evaluation of the sensor signal in the radio sensor node, this generation of a transmission signal is particularly energy-saving. In this case, the energy-intensive evaluation of the transmission signal is carried out by a user of the wireless sensor node. To evaluate the transmission signal, a calibration curve is measured, for example, in a test facility belonging to the manufacturer of the radio sensor node, which curve represents the transmission signal as a function of the measured variable and is made available to a user of the radio sensor node.

Die Erfindung sieht vor, dass alternativ von der Signalverarbeitungseinheit als Übertragungssignal ein Effektivwert des Sensorsignals erzeugt wird. Diese zur vorgenannten Ausgestaltung alternative Ausgestaltung der Erfindung wird vorzugsweise dann eingesetzt, wenn dem Funksensorknoten durch das Energieernten ausreichend Energie zur Berechnung des Effektivwerts zur Verfügung steht.The invention provides that an effective value of the sensor signal is alternatively generated by the signal processing unit as the transmission signal. This embodiment of the invention, which is an alternative to the aforementioned embodiment, is preferably used when the radio sensor node has sufficient energy available to calculate the effective value due to energy harvesting.

Bei einer weiteren Ausgestaltung der Erfindung weist der Funksensorknoten einen Signaleingang, dem das Sensorsignal zugeführt wird, und eine Umschaltlogik, durch die der Signaleingang wechselweise mit der Energieernteeinheit und der Signalverarbeitungseinheit verbindbar ist, auf. Diese Ausgestaltung der Erfindung realisiert die abwechselnde Zuführung des Sensorsignals zu der Signalverarbeitungseinheit und der Energieernteeinheit durch eine Umschaltlogik, die den Signaleingang abwechselnd mit der Signalverarbeitungseinheit und der Energieernteeinheit verbindet.In a further embodiment of the invention, the radio sensor node has a signal input, to which the sensor signal is fed, and switching logic, by means of which the signal input can be connected alternately to the energy harvesting unit and the signal processing unit. This refinement of the invention implements the alternating supply of the sensor signal to the signal processing unit and the energy harvesting unit by means of switching logic which alternately connects the signal input to the signal processing unit and the energy harvesting unit.

Eine weitere Ausgestaltung der Erfindung sieht eine Spannungsbegrenzungseinheit zum Schutz des Signaleingangs vor Überspannungen vor. Diese Ausgestaltung der Erfindung erhöht vorteilhaft die Robustheit des Signaleingangs gegen Stoßspannungen. Diese können verursacht sein durch direkte Einkopplungen oder durch induktive Einkopplungen (beispielsweise von Stromstößen in nahe vorbeilaufenden Strombahnen) oder durch kapazitive Einkopplungen, die insbesondere in der Umgebung von Hochspannungsanlagen auftreten können.A further embodiment of the invention provides a voltage limiting unit to protect the signal input against overvoltages. This refinement of the invention advantageously increases the robustness of the signal input against surge voltages. These can be caused by direct couplings or by inductive couplings (e.g. from current surges in nearby current paths) or by capacitive couplings, which can occur particularly in the vicinity of high-voltage systems.

Eine weitere Ausgestaltung der Erfindung sieht vor, dass der Signaleingang aus einem Sensorknotengehäuse des Funksensorknotens herausgeführte Kontakte aufweist. Dadurch wird eine Kontaktierung des Signaleingangs von außen ermöglicht. Ferner kann einer der Kontakte genutzt werden, um den Kontakt außerhalb des Funksensorknotens auf ein Massepotential zu legen.A further embodiment of the invention provides that the signal input has contacts led out of a sensor node housing of the wireless sensor node. This enables contacting of the signal input from the outside. Furthermore, one of the contacts can be used to ground the contact outside of the radio sensor node.

Eine weitere Ausgestaltung der Erfindung sieht vor, dass der Funksensorknoten ein in einem Kunststoff mit niedriger Permittivität vergossenes Sensorknotengehäuse aufweist. Dadurch werden die Funksignale der Funkeinheit vorteilhaft durch das Sensorknotengehäuse kaum gedämpft.A further embodiment of the invention provides that the radio sensor node has a sensor node housing cast in a plastic with low permittivity. As a result, the radio signals of the radio unit are advantageously hardly attenuated by the sensor node housing.

Weitere Ausgestaltungen der Erfindung sehen vor, dass die Funkeinheit eine Antenne, beispielsweise eine Ringantenne mit einer oder mehreren Windungen, aufweist und dazu ausgebildet ist, mit der Antenne wechselweise das Funksignal zu senden und aus einem in einer Umgebung des Funksensorknotens vorhandenen Magnetfeld induktiv Energie zu ernten und/oder eine Magnetfeldstärke eines in einer Umgebung des Funksensorknotens vorhandenen Magnetfeldes zu erfassen. Diese Ausgestaltungen der Erfindung sehen also vor, die Antenne des Funksensorknotens nicht nur dem Senden von Funksignalen, sondern außerdem zum Ernten von Energie aus einem Magnetfeld und/oder zum Erfassen einer Magnetfeldstärke eines Magnetfeldes in der Umgebung des Funksensorknotens zu verwenden. Dadurch wird die Antenne vorteilhaft auch zur Energieversorgung des Funksensorknotens und/oder als Magnetfeldsensor genutzt.Further refinements of the invention provide that the radio unit has an antenna, for example a ring antenna with one or more windings, and is designed for this purpose is to alternately send the radio signal with the antenna and to inductively harvest energy from a magnetic field present in an area surrounding the radio sensor node and/or to detect a magnetic field strength of a magnetic field present in an area surrounding the radio sensor node. These refinements of the invention therefore provide for using the antenna of the wireless sensor node not only for sending wireless signals, but also for harvesting energy from a magnetic field and/or for detecting a magnetic field strength of a magnetic field in the vicinity of the wireless sensor node. As a result, the antenna is advantageously also used to supply energy to the wireless sensor node and/or as a magnetic field sensor.

Eine weitere Ausgestaltung der Erfindung sieht vor, dass der Funksensorknoten an einer elektrisch leitfähigen Oberfläche angeordnet ist und einen mit der elektrisch leitfähigen Oberfläche elektrisch verbundenen Masseanschluss aufweist. Außerdem kann der Funksensorknoten eine mit der elektrisch leitfähigen Oberfläche verbundene elektromagnetische Abschirmung aufweisen. Diese Ausgestaltung der Erfindung nutzt eine elektrisch leitfähige Oberfläche, an der der Funksensorknoten angeordnet ist, zur Potentialanbindung des Funksensorknotens und einer elektromagnetischen Abschirmung des Funksensorknotens.A further embodiment of the invention provides that the radio sensor node is arranged on an electrically conductive surface and has a ground connection that is electrically connected to the electrically conductive surface. In addition, the wireless sensor node may include an electromagnetic shield connected to the electrically conductive surface. This refinement of the invention uses an electrically conductive surface, on which the radio sensor node is arranged, for the potential connection of the radio sensor node and an electromagnetic shielding of the radio sensor node.

Bei einer weiteren Ausgestaltung der Erfindung weist der Funksensorknoten eine Energiespeichereinheit zur Speicherung von Energie auf. Die Energiespeichereinheit weist beispielsweise einen Superkondensator und/oder einen Akkumulator auf. Wenn die Energiespeichereinheit einen Superkondensator und einen Akkumulator aufweist, wird der Akkumulator beispielsweise nur geladen, wenn der Superkondensator auf eine Nennspannung aufgeladen ist. Diese Ausgestaltungen der Erfindung ermöglichen die Speicherung insbesondere der aus dem Sensorsignal geernteten Energie, wenn die geerntete Energie momentan nicht zur Energieversorgung des Funksensorknotens benötigt wird. Die Verwendung eines Superkondensators und eines Akkumulators kombiniert die schnelle Be- und Entladbarkeit eines Superkondensators mit der höheren Kapazität eines Akkumulators. Außerdem haben Superkondensatoren höhere Lebensdauern als Akkumulatoren, so dass der Superkondensator noch lange verwendbar ist, wenn die Lebensdauer des Akkumulators bereits abgelaufen ist. Das Laden des Akkumulators erfolgt nur nach abgeschlossener Aufladung des Superkondensators auf eine Nennspannung. Dies wird durch eine Entkopplungsschaltung erreicht. Wenn der Akkumulator nach einigen Jahren Betrieb defekt wird, so baut er keine Spannung mehr auf. Die Entkoppelungsschaltung vermeidet dann eine Entladung des Superkondensators durch den defekten Akkumulator, so dass der Funksensorknoten weiterhin mit Energie aus dem Superkondensator versorgt werden kann. Die parallele Installation des Superkondensators und des Akkumulators hat den Vorteil, dass - je nach Energieernte und Zykluszeiten - in den ersten Jahren des Einsatzes des Funksensorknotens deutlich mehr Mess- und Rechenaufgaben abgearbeitet werden können als mit alleiniger Speisung aus dem Superkondensator.In a further embodiment of the invention, the radio sensor node has an energy storage unit for storing energy. The energy storage unit has, for example, a supercapacitor and/or an accumulator. For example, if the energy storage unit includes a supercapacitor and an accumulator, the accumulator is charged only when the supercapacitor is charged to a nominal voltage. These refinements of the invention make it possible in particular to store the energy harvested from the sensor signal when the harvested energy is not currently required to supply energy to the wireless sensor node. The use of a supercapacitor and an accumulator combines fast charging and discharging a supercapacitor with the higher capacity of an accumulator. In addition, supercapacitors have longer lifetimes than accumulators, so that the supercapacitor can still be used for a long time after the battery life has expired. The accumulator is only charged after the supercapacitor has been charged to a nominal voltage. This is achieved by a decoupling circuit. If the accumulator becomes defective after a few years of operation, it no longer builds up any voltage. The decoupling circuit then prevents the supercapacitor from being discharged by the defective accumulator, so that the radio sensor node can continue to be supplied with energy from the supercapacitor. The parallel installation of the supercapacitor and the accumulator has the advantage that - depending on the energy harvest and cycle times - significantly more measurement and calculation tasks can be processed in the first years of use of the wireless sensor node than with the sole supply from the supercapacitor.

Bei dem erfindungsgemäßen Verfahren zum Betreiben eines erfindungsgemäßen Funksensorknotens werden dementsprechend mit der Sensoreinheit die Messgröße erfasst und das Sensorsignal ausgegeben, das Sensorsignal wird wechselweise der Energieernteeinheit und der Signalverarbeitungseinheit zugeführt, mit der Signalverarbeitungseinheit wird das Übertragungssignal aus dem Sensorsignal erzeugt, mit der Funkeinheit wird das Übertragungssignal als ein Funksignal gesendet, und mit der Energieernteeinheit wird Energie aus dem Sensorsignal geerntet.In the method according to the invention for operating a radio sensor node according to the invention, the measured variable is accordingly recorded with the sensor unit and the sensor signal is output, the sensor signal is fed alternately to the energy harvesting unit and the signal processing unit, the transmission signal is generated from the sensor signal with the signal processing unit, the transmission signal is processed with the radio unit sent as a radio signal and the energy harvesting unit harvests energy from the sensor signal.

Die oben beschriebenen Eigenschaften, Merkmale und Vorteile dieser Erfindung sowie die Art und Weise, wie diese erreicht werden, werden klarer und deutlicher verständlich im Zusammenhang mit der folgenden Beschreibung von Ausführungsbeispielen, die im Zusammenhang mit den Zeichnungen näher erläutert werden. Dabei zeigen:

FIG 1
ein Blockdiagramm eines Funksensorknotens,
FIG 2
einen Schaltplan einer Gleichrichterschaltung und einer Mittelungsschaltung zum Erzeugen eines Ãœbertragungssignals,
FIG 3
einen Schaltplan einer Energiespeichereinheit.
The properties, features and advantages of this invention described above, and the manner in which they are achieved, will become clearer and more clearly understood in connection with the following description of exemplary embodiments, which will be explained in more detail in connection with the drawings. show:
FIG 1
a block diagram of a wireless sensor node,
FIG 2
a circuit diagram of a rectifier circuit and an averaging circuit for generating a transmission signal,
3
a circuit diagram of an energy storage unit.

Einander entsprechende Teile sind in den Figuren mit denselben Bezugszeichen versehen.Corresponding parts are provided with the same reference symbols in the figures.

Figur 1 zeigt ein Blockdiagramm eines Ausführungsbeispiels eines erfindungsgemäßen Funksensorknotens 1. Der Funksensorknoten 1 umfasst ein Sensorknotengehäuse 3, eine Sensoreinheit 5, einen Signaleingang 7, eine Umschaltlogik 9, eine Signalverarbeitungseinheit 11, eine Energieernteeinheit 13 mit einer Energiespeichereinheit 15, eine Funkeinheit 17 und eine elektromagnetische Abschirmung 19. figure 1 shows a block diagram of an embodiment of a radio sensor node 1 according to the invention. The radio sensor node 1 comprises a sensor node housing 3, a sensor unit 5, a signal input 7, a switching logic 9, a signal processing unit 11, an energy harvesting unit 13 with an energy storage unit 15, a radio unit 17 and an electromagnetic shield 19 .

Mit der Sensoreinheit 5 werden eine Messgröße erfasst und ein die Messgröße repräsentierendes analoges elektrisches Sensorsignal S an den Signaleingang 7 ausgegeben. Die Sensoreinheit 5 weist beispielsweise einen Temperatursensor zum Erfassen einer Temperatur als Messgröße auf, kann jedoch auch einen Sensor zum Erfassen einer anderen Messgröße aufweisen. Das Sensorsignal S ist eine von der Sensoreinheit 5 erzeugte elektrische Spannung, beispielsweise eine Spannung im einstelligen Voltbereich.A measured variable is detected with the sensor unit 5 and an analog electrical sensor signal S representing the measured variable is output to the signal input 7 . The sensor unit 5 has, for example, a temperature sensor for detecting a temperature as a measured variable, but can also have a sensor for detecting another measured variable. The sensor signal S is an electrical voltage generated by the sensor unit 5, for example a voltage in the single-digit volt range.

Die Umschaltlogik 9 verbindet den Signaleingang 7 wechselweise mit der Signalverarbeitungseinheit 11 und der Energieernteeinheit 13 und führt das Sensorsignal S damit wechselweise der Signalverarbeitungseinheit 11 und der Energieernteeinheit 13 zu. Beispielsweise weist die Umschaltlogik 9 zu diesem Zweck verlustarme Halbleiterschalter, beispielsweise Metall-Oxid-Halbleiter-Feldeffekttransistoren (MOSFET), und eine Steuereinheit zur Ansteuerung der Halbleiterschalter auf.The switching logic 9 connects the signal input 7 alternately to the signal processing unit 11 and the energy harvesting unit 13 and thus supplies the sensor signal S to the signal processing unit 11 and the energy harvesting unit 13 alternately. For example, the switching logic 9 has, for this purpose, low-loss semiconductor switches, for example metal-oxide-semiconductor field effect transistors (MOSFET), and a control unit for driving the semiconductor switches.

Die Signalverarbeitungseinheit 11 erzeugt aus dem Sensorsignal S ein Ãœbertragungssignal T. Beispielsweise erzeugt die Signalverarbeitungseinheit 11 als Ãœbertragungssignal T einen Mittelwert des gleichgerichteten Sensorsignals S, siehe dazu Figur 2.The signal processing unit 11 generates a transmission signal T from the sensor signal S. For example, the signal processing unit 11 generates a mean value of the rectified sensor signal S as the transmission signal T, cf figure 2 .

Figur 2 zeigt beispielhaft einen Schaltplan einer Gleichrichterschaltung 21 und einer Mittelungsschaltung 23 zum Erzeugen des Übertragungssignals T als ein Mittelwert des gleichgerichteten Sensorsignals S. Die Gleichrichterschaltung 21 ist als eine von vier Dioden 25 gebildete Brückengleichrichterschaltung ausgebildet. Die Mittelungsschaltung 23 ist der Gleichrichterschaltung 21 nachgeschaltet und weist eine Induktivität 27, einen Mittelungskondensator 29 und einen zu dem Mittelungskondensator 29 parallel geschalteten Mittelungswiderstand 31 auf. In Figur 2 ist angenommen, dass der Signaleingang 7 über die Umschaltlogik 9 mit der Signalverarbeitungseinheit 11 verbunden ist, wobei die Umschaltlogik 9 in Figur 2 nicht dargestellt ist. Der Signaleingang 7 ist durch eine von einem Varistor gebildete Spannungsbegrenzungseinheit 33 vor Überspannungen geschützt. Beispielsweise ist die Spannungsbegrenzungseinheit 33 dazu ausgelegt, einen einlaufenden, über 5 ms abklingenden Spannungsstoß mit einer Spannungsspitze von 100 V auf 15 V bis 20 V zu begrenzen. Das Übertragungssignal T ist eine an der Parallelschaltung des Mittelungskondensators 29 und des Mittelungswiderstands 31 anliegende Spannung. Zum Auswerten des auf diese Weise erzeugten Übertragungssignals T wird in einem Prüffeld des Herstellers des Funksensorknotens 1 eine Kalibrierkurve ausgemessen, die das Übertragungssignal T als eine Übertragungsfunktion der Messgröße darstellt und einem Benutzer des Funksensorknotens 1 zur Verfügung gestellt wird. Idealerweise wird für die Ermittlung der Übertragungsfunktion im Prüffeld ein für das Messsignal typischer Zeitverlauf gewählt, der der erwarteten Messgröße auf der Anlage in etwa entspricht. figure 2 1 shows a circuit diagram of a rectifier circuit 21 and an averaging circuit 23 for generating the transmission signal T as an average value of the rectified sensor signal S. The rectifier circuit 21 is designed as a bridge rectifier circuit formed by four diodes 25. The averaging circuit 23 is connected downstream of the rectifier circuit 21 and has an inductor 27 , an averaging capacitor 29 and an averaging resistor 31 connected in parallel with the averaging capacitor 29 . In figure 2 it is assumed that the signal input 7 is connected to the signal processing unit 11 via the switching logic 9, the switching logic 9 in figure 2 is not shown. The signal input 7 is protected against overvoltages by a voltage limiting unit 33 formed by a varistor. For example, the voltage limiting unit 33 is designed to limit an incoming voltage surge that decays over 5 ms and has a voltage peak of 100 V to 15 V to 20 V. The transmission signal T is a voltage present at the parallel connection of the averaging capacitor 29 and the averaging resistor 31 . To evaluate the transmission signal T generated in this way, a calibration curve is measured in a test facility of the manufacturer of the radio sensor node 1, which represents the transmission signal T as a transmission function of the measured variable and is made available to a user of the radio sensor node 1. Ideally, to determine the transfer function in the test field, a typical time course for the measurement signal is selected, which roughly corresponds to the expected measurement variable on the system.

Die in Figur 2 gezeigte Ausführung der Signalverarbeitungseinheit 11 zum Erzeugen des Übertragungssignals T als ein Mittelwert des gleichgerichteten Sensorsignals S erfordert keine aufwändige Auswertung des Sensorsignals S in dem Funksensorknoten 1 und ist deshalb besonders energiesparend. Wenn ausreichend geerntete Energie zur Verfügung steht, kann die Signalverarbeitungseinheit 11 stattdessen aufwändiger ausgeführt sein. Beispielsweise kann die Signalverarbeitungseinheit 11 einen integrierten Schaltkreis aufweisen, der als Übertragungssignal T einen Effektivwert (RMS) des Sensorsignals S berechnet. Beispielsweise wird der Effektivwert über eine Zeitperiode von etwa 100 ms mit einer Abtastfrequenz von mehr als 3 kHz gebildet. Bei größeren Funksensorknoten 1 kann die Messwertverarbeitung auch mehrere Signale umfassen, einen Messwertspeicher enthalten und eine aufwändigere Verarbeitung beinhalten.In the figure 2 shown embodiment of the signal processing unit 11 for generating the transmission signal T as a The mean value of the rectified sensor signal S does not require any complex evaluation of the sensor signal S in the radio sensor node 1 and is therefore particularly energy-saving. If sufficient harvested energy is available, the signal processing unit 11 can instead be implemented in a more complex manner. For example, the signal processing unit 11 can have an integrated circuit that calculates an effective value (RMS) of the sensor signal S as the transmission signal T. FIG. For example, the effective value is formed over a time period of about 100 ms with a sampling frequency of more than 3 kHz. In the case of larger radio sensor nodes 1, the measured value processing can also include a number of signals, contain a measured value memory and contain more complex processing.

Die Energieernteeinheit 13 ist zum Ernten von Energie aus dem Sensorsignal S ausgebildet, die zur Energieversorgung des Funksensorknotens 1 verwendet wird. Die Energieernteeinheit 13 weist eine Energiespeichereinheit 15 auf, die zur Speicherung von Energie ausgebildet ist, wenn die geerntete Energie momentan nicht zur Energieversorgung des Funksensorknotens 1 benötigt wird.The energy harvesting unit 13 is designed to harvest energy from the sensor signal S, which energy is used to supply the radio sensor node 1 with energy. The energy harvesting unit 13 has an energy storage unit 15 which is designed to store energy when the harvested energy is not currently required to supply the wireless sensor node 1 with energy.

Figur 3 zeigt einen Schaltplan eines Ausführungsbeispiels der Energiespeichereinheit 15, wobei angenommen ist, dass die Energiespeichereinheit 15 über die Umschaltlogik 9 mit dem Signaleingang 7 verbunden ist, und wobei wie in Figur 2 die Umschaltlogik 9 nicht dargestellt ist. Die Energiespeichereinheit 15 dieses Ausführungsbeispiels weist einen Superkondensator 35, einen Akkumulator 37, eine Überlaufeinheit 39 mit einem integrierten Überladeschutz und eine Sperrdiode 41 auf und ist über eine Gleichrichterschaltung 21 mit dem Signaleingang 7 verbunden, wobei die Gleichrichterschaltung 21 mit der in Figur 2 gezeigten Gleichrichterschaltung 21 übereinstimmen oder separat ausgeführt sein kann. Der Superkondensator 35 und der Akkumulator 37 sind durch die Überlaufeinheit 39 entkoppelt, aber prinzipiell parallel zueinander geschaltet. Die Überlaufeinheit 39 leitet überschüssige Energie in den Akkumulator 37, wenn der Superkondensator 35 auf eine Nennspannung aufgeladen ist, das heißt der Akkumulator 37 wird nur dann geladen, wenn der Superkondensator 35 bereits auf die Nennspannung aufgeladen ist. Wenn der Akkumulator 37 sein Lebensdauerende erreicht, wird die Energiespeichereinheit 15 nur noch mit dem Superkondensator 35 betrieben. figure 3 shows a circuit diagram of an exemplary embodiment of the energy storage unit 15, it being assumed that the energy storage unit 15 is connected to the signal input 7 via the switching logic 9, and as in FIG figure 2 the switching logic 9 is not shown. The energy storage unit 15 of this exemplary embodiment has a supercapacitor 35, an accumulator 37, an overflow unit 39 with integrated overcharge protection and a blocking diode 41 and is connected to the signal input 7 via a rectifier circuit 21, with the rectifier circuit 21 having the in figure 2 shown rectifier circuit 21 match or can be performed separately. The supercapacitor 35 and the accumulator 37 are decoupled by the overflow unit 39, but are in principle connected in parallel to one another. The overflow unit 39 directs excess Energy into the accumulator 37 when the supercapacitor 35 is charged to a nominal voltage, ie the accumulator 37 is charged only when the supercapacitor 35 is already charged to the nominal voltage. When the accumulator 37 reaches its end of life, the energy storage unit 15 is only operated with the supercapacitor 35 .

Die Funkeinheit 17 weist eine Antenne 43 auf, mit der das Übertragungssignal T als ein Funksignal gesendet wird. Die Antenne 43 ist als eine Ringantenne mit einer oder mehreren Windungen ausgebildet. Vorzugsweise ist die Funkeinheit 17 ferner dazu ausgebildet, mit der Antenne 43 wechselweise das Funksignal zu senden und aus einem in einer Umgebung des Funksensorknotens 1 vorhandenen Magnetfeld induktiv Energie zu ernten und/oder eine Magnetfeldstärke eines in einer Umgebung des Funksensorknotens 1 vorhandenen Magnetfeldes zu erfassen.The radio unit 17 has an antenna 43 with which the transmission signal T is sent as a radio signal. The antenna 43 is designed as a ring antenna with one or more turns. Preferably, the radio unit 17 is also configured to alternately transmit the radio signal with the antenna 43 and to inductively harvest energy from a magnetic field present in the vicinity of the radio sensor node 1 and/or to detect a magnetic field strength of a magnetic field present in the vicinity of the radio sensor node 1.

Die elektromagnetische Abschirmung 19 ist als eine niederinduktive Leiterschleife ausgebildet, die zur Abschirmung elektromagnetischer Felder in dem Sensorknotengehäuse 3 um die elektrischen und elektronischen Komponenten des Funksensorknotens 1 herum verläuft.The electromagnetic shielding 19 is designed as a low-inductance conductor loop, which runs around the electrical and electronic components of the wireless sensor node 1 in order to shield electromagnetic fields in the sensor node housing 3 .

Der Signaleingang 7 weist aus dem Sensorknotengehäuse 3 herausgeführte Kontakte 44, 45 auf, über die der Signaleingang 7 von außen kontaktierbar ist. Über die Kontakte 44, 45 kann beispielsweise eine externe Sensoreinheit 5 mit dem Signaleingang 7 verbunden werden, um dem Signaleingang 7 ein von der externen Sensoreinheit 5 ausgegebenes Sensorsignal S zuzuführen. Ein herausgeführter Kontakt 45 und die elektromagnetische Abschirmung 19 sind mit einem aus dem Sensorknotengehäuse 3 herausgeführten Masseanschluss 47 verbunden. Der Masseanschluss 47 ist mit einer elektrisch leitfähigen Oberfläche 49 elektrisch verbunden, an der der Funksensorknoten 1 angeordnet ist.The signal input 7 has contacts 44, 45 led out of the sensor node housing 3, via which the signal input 7 can be contacted from the outside. For example, an external sensor unit 5 can be connected to the signal input 7 via the contacts 44 , 45 in order to feed a sensor signal S output by the external sensor unit 5 to the signal input 7 . A contact 45 led out and the electromagnetic shield 19 are connected to a ground connection 47 led out of the sensor node housing 3 . The ground connection 47 is electrically connected to an electrically conductive surface 49 on which the radio sensor node 1 is arranged.

Optional kann die Energieernteeinheit 13 über aus dem Sensorknotengehäuse 3 herausgeführte Zusatzkontakte 51, 52 Energie ernten.The energy harvesting unit 13 can optionally harvest energy via additional contacts 51 , 52 led out of the sensor node housing 3 .

Das Sensorknotengehäuse 3 ist in einem Kunststoff mit niedriger Permittivität vergossen, so dass die Funksignale der Antenne 43 kaum gedämpft werden.The sensor node housing 3 is cast in a plastic with a low permittivity, so that the radio signals from the antenna 43 are hardly attenuated.

Der Funksensorknoten 1 wird beispielsweise in einer elektromagnetisch hoch belasteten Umgebung eingesetzt.The radio sensor node 1 is used, for example, in an electromagnetically highly loaded environment.

Obwohl die Erfindung im Detail durch bevorzugte Ausführungsbeispiele näher illustriert und beschrieben wurde, so ist die Erfindung nicht durch die offenbarten Beispiele eingeschränkt und andere Variationen können vom Fachmann hieraus abgeleitet werden, ohne den Schutzumfang der Erfindung zu verlassen.Although the invention has been illustrated and described in more detail by means of preferred exemplary embodiments, the invention is not restricted by the disclosed examples and other variations can be derived therefrom by a person skilled in the art without departing from the protective scope of the invention.

BezugszeichenlisteReference List

11
Funksensorknotenwireless sensor node
33
Sensorknotengehäusesensor node housing
55
Sensoreinheitsensor unit
77
Signaleingangsignal input
99
Umschaltlogikswitching logic
1111
Signalverarbeitungseinheitsignal processing unit
1313
Energieernteeinheitenergy harvesting unit
1515
Energiespeichereinheitenergy storage unit
1717
Funkeinheitradio unit
1919
elektromagnetische Abschirmungelectromagnetic shielding
2121
Gleichrichterschaltungrectifier circuit
2323
Mittelungsschaltungaveraging circuit
2525
Diodediode
2727
Induktivitätinductance
2929
Mittelungskondensatoraveraging capacitor
3131
Mittelungswiderstandaveraging resistance
3333
SpannungsbegrenzungseinheitVoltage Limiting Unit
3535
Superkondensatorsupercapacitor
3737
Akkumulatoraccumulator
3939
Ãœberlaufeinheitoverflow unit
4141
Sperrdiodeblocking diode
4343
Antenneantenna
44, 4544, 45
herausgeführter Kontaktbrought out contact
4747
Masseanschlussground connection
4949
elektrisch leitfähige Oberflächeelectrically conductive surface
51, 5251, 52
Zusatzkontaktadditional contact
SS
Sensorsignalsensor signal
TT
Ãœbertragungssignaltransmission signal

Claims (12)

  1. Radio sensor node (1) comprising
    - a sensor unit (5) for capturing a measurement variable and outputting an analogue electrical sensor signal (S),
    - an energy harvesting unit (13) for harvesting energy from the sensor signal (S),
    - a signal processing unit (11) for generating a transmission signal (T) from the sensor signal (S), and
    - a radio unit (17) for transmitting the transmission signal (T) as a radio signal,
    - wherein the sensor signal (S) can be alternately supplied to the energy harvesting unit (13) and to the signal processing unit (11), and
    - wherein the signal processing unit (11) has an averaging circuit (23) for generating the transmission signal (T) as an average value of the sensor signal (S) rectified with a rectifier circuit (21), or wherein the signal processing unit (11) generates a root mean square value of the sensor signal (S) as the transmission signal (T).
  2. Radio sensor node (1) according to one of the preceding claims, having a signal input (7), to which the sensor signal (S) is supplied, and having a changeover logic unit (9) which can be used to alternately connect the signal input (7) to the energy harvesting unit (13) and the signal processing unit (11) .
  3. Radio sensor node (1) according to Claim 2, having a voltage limiting unit (33) for protecting signal input (7) from overvoltages.
  4. Radio sensor node (1) according to Claim 2 or 3, wherein the signal input (7) has contacts (44, 45) routed out of a sensor node housing (3) of the radio sensor node (1).
  5. Radio sensor node (1) according to one of the preceding claims, having a sensor node housing (3) encapsulated in a low-permittivity plastic.
  6. Radio sensor node (1) according to one of the preceding claims, wherein the radio unit (17) has an antenna (43) and is designed to use the antenna (43) to alternately transmit the radio signal and to inductively harvest energy from a magnetic field present in an environment of the radio sensor node (1).
  7. Radio sensor node (1) according to one of the preceding claims, wherein the radio unit (17) has an antenna (43) and is designed to use the antenna (43) to alternately transmit the radio signal and to capture a magnetic field strength of a magnetic field present in an environment of the radio sensor node (1).
  8. Radio sensor node (1) according to one of the preceding claims, which is arranged on an electrically conductive surface (49) and has an earth connection (47) electrically connected to the electrically conductive surface (49).
  9. Radio sensor node (1) according to Claim 8, which has an electromagnetic shield (19) connected to the electrically conductive surface (49).
  10. Radio sensor node (1) according to one of the preceding claims, having an energy storage unit (15) for storing energy, wherein the energy storage unit (15) has a super capacitor (35) and/or a rechargeable battery (37).
  11. Radio sensor node (1) according to Claim 10, wherein the energy storage unit (15) has a super capacitor (35) and a rechargeable battery (37), and the rechargeable battery (37) is charged to a nominal voltage only after charging of the super capacitor (35) has been completed.
  12. Method for operating a radio sensor node (1) according to one of the preceding claims, wherein
    - the sensor unit (5) is used to capture the measurement variable and to output the sensor signal (S),
    - the sensor signal (S) is alternately supplied to the energy harvesting unit (13) and to the signal processing unit (11),
    - the signal processing unit (11) is used to generate the transmission signal (T) from the sensor signal (S), wherein an averaging circuit (23) of the signal processing unit (11) generates the transmission signal (T) as an average value of the sensor signal (S) rectified with a rectifier circuit (21), or wherein the signal processing unit (11) generates a root mean square value of the sensor signal (S) as the transmission signal (T),
    - the radio unit (17) is used to transmit the transmission signal (T) as a radio signal, and
    - the energy harvesting unit (13) is used to harvest energy from the sensor signal (S).
EP18785850.1A 2018-09-26 2018-09-26 Wireless sensor node Active EP3830804B1 (en)

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