Method for transmitting energy to a sensor and sensor device

Abstract

The invention relates to a method and a sensor device for transmitting energy to a sensor. A method for transmitting energy to a sensor, comprising: transferring energy from a primary side to a secondary side, the sensor being arranged on the secondary side, the primary side and the secondary side being coupled to each other via a primary coil and a secondary coil, and the transfer of energy taking place by means of these two coils, the primary coil and the secondary coil thereby being designed for bidirectional transmission of data; acquiring a measured variable by means of the sensor; transmitting a value dependent on the measured variable from the secondary side to the primary side; requesting an energy pulse from the secondary side to the primary side when an event occurs that requires more energy; interrupting the transmission of the value dependent on the measured variable; transmitting at least one energy pulse from the primary side to the secondary side, the energy pulse being transmitted in an event-controlled manner, and returning to a normal mode after acquiring the measured variable and transmitting the value dependent on the measured variable to the primary side. A sensor device is disclosed that carries out the method.

Description

Technical Field

[0001] This invention relates to a method for transferring energy to a sensor. The invention also relates to a corresponding sensor device for implementing this method. Background Technology

[0002] The "sensor device" consists of a sensor connected inductively to it by a cable. The cable is in turn connected to a transmitter. For example, products sold by the applicant under the name "Memosens" are known. This type of sensor uses inductive energy and data transmission by means of two coils between the sensor and the cable.

[0003] For such inductive energy and data transmission systems, efficiency and communication quality typically depend on the point of operation, and the system operates at the target point of operation (with the corresponding transmission voltage and modulation). However, depending on system tolerances, deviations in communication quality and energy transmission may occur. The system is usually designed to operate continuously around this point of operation.

[0004] Increasing the primary voltage (i.e., the voltage at the primary coil) makes it possible to transfer more energy. However, this causes the voltage level on the secondary side to rise. This, in turn, can lead to malfunction or failure of the secondary circuitry. In these systems, a fixed operating point is required, for example, for secure communication. Summary of the Invention

[0005] This invention is based on the aim of transmitting more energy to sensors connected to cables.

[0006] This objective is achieved by a method comprising the following steps: transferring energy from the primary side to the secondary side, wherein a sensor is arranged on the secondary side, wherein the primary side and the secondary side are coupled to each other via a primary coil and a secondary coil, and the energy transfer occurs by means of these two coils, wherein the primary coil and the secondary coil are thus designed to transmit data bidirectionally; acquiring a measured variable by means of the sensor; transmitting a value depending on the measured variable from the secondary side to the primary side; requesting an energy pulse from the secondary side to the primary side when an event requiring more energy occurs; interrupting the transmission depending on the value of the measured variable; transmitting at least one energy pulse from the primary side to the secondary side, wherein the energy pulse is transmitted in an event-controlled manner, and after acquiring the measured variable, returning to normal mode and transmitting a value depending on the measured variable back to the primary side.

[0007] In an improved scheme, specifically before the transmission of the value of the measured variable is interrupted and after the requested energy pulse occurs, the acquisition of the measured variable is interrupted.

[0008] This invention enables increased energy transfer via the sensing interface by briefly delivering higher-energy pulses. Therefore, more energy is available on the sensor side to perform sensor functions. In this scenario, the target operating point is briefly held, during which no communication occurs.

[0009] An improved approach specifies that the method includes the following steps: storing additional energy from the energy pulse on the secondary side.

[0010] Energy pulses are transmitted in an event-controlled manner. For example, such events could be: the energy storage on the secondary side is empty or below a threshold; the sensor will switch to a special mode, such as a mode for performing software or firmware updates, a cleaning mode, or whether to measure a specific range more precisely. An event is also considered when a large amount of energy is about to occur. Therefore, the sensor will request additional energy before this event begins. Even if the energy storage is not particularly empty, it will be filled in this case.

[0011] This objective is also achieved by a sensor device for performing the above-described method, the sensor device comprising: a primary side including a power supply unit, a primary coil, and a first data processing unit, the primary coil being connected to the power supply unit and configured to transmit energy and energy pulses to a secondary coil and configured to transmit or receive data bidirectionally, the first data processing unit being configured to control and optionally regulate the energy transmission and designed to generate, control, and optionally regulate energy pulses by means of the power supply unit and designed to transmit them to the secondary coil; and a secondary side having a sensor including a secondary coil, at least one voltage limiter, a sensor element, and a second data processing unit, the secondary coil being configured to receive energy and energy pulses from the primary coil and configured to transmit or receive data bidirectionally, the at least one voltage limiter being used to limit the input voltage at the secondary coil, wherein the voltage limiter is connected to the secondary coil, the sensor element being used to detect at least one measured variable, and the second data processing unit being connected at least to the sensor element and to the secondary coil, wherein the second data processing unit is designed to generate data related to the measured variable.

[0012] One improved embodiment specifies that the sensor device includes: at least one energy storage on the secondary side, the energy storage being connected to a secondary coil, the energy storage storing at least energy from an energy pulse.

[0013] Because of the voltage limiter on the secondary side, the maximum voltage level defined on the secondary side will not be exceeded. If the circuit is designed in principle to operate at this level and proves to be unrepairable, and integrates circuitry that can store the increased voltage / energy level, then this additional energy can be effectively stored for later use.

[0014] Control over when to transmit additional energy pulses, for how long to transmit them, and what other parameters they have occurs internally, for example, by means of one or more data processing units. The system uses these control parameters to coordinate internal measurement, calculation, communication cycles, charging and discharging processes, and other processes depending on the operating point. In an improved embodiment, control is performed on the primary side (e.g., a first data processing unit or a connected measurement transducer), and the secondary side (i.e., a sensor with a second data processing unit) follows the control parameters.

[0015] One improvement specifies that the sensor device includes energy storage on the primary side. This improvement is particularly useful, for example, in two-wire devices where limited energy is naturally available. In two-wire devices, energy pulses are transmitted during regularly occurring periods of low energy consumption, preventing excessive strain on the energy management of the two-wire device.

[0016] In principle, a four-wire device can also include such energy storage on the primary side. However, it can be assumed, in principle, that the amount of energy reaching the maximum transmittable value can be provided by the four-wire device on the primary side. Here, the limiting factor for the amount of energy is the fact that communication must be activated for "normal operation" of the measured value.

[0017] One improved design specifies that the sensor device includes: a control element, particularly a transistor, on the primary side, for generating energy pulses.

[0018] One improved embodiment specifies that the sensor device includes: a control element, particularly a transistor, on the secondary side, for transmitting energy pulses to an energy storage or consumption device.

[0019] One improved embodiment specifies that the sensor device includes: a regulator, particularly a linear regulator or a switching regulator, which is located on the secondary side and connected downstream of the energy storage.

[0020] One proposed improvement is to design the regulator as a buck regulator.

[0021] One improved embodiment specifies that the sensor device includes: an isolation circuit, particularly at least one diode, which is connected between the energy storage and the sensor element. Attached Figure Description

[0022] This will be explained in more detail with reference to the following diagram.

[0023] Figure 1 The sensor device requiring protection is shown.

[0024] Figure 2 The sensor device with required protection, including the sensor and cable, is shown along with additional details.

[0025] Figure 3 The time-voltage diagram of the method requiring protection is shown. Detailed Implementation

[0026] In these figures, the same features are identified by the same reference numerals.

[0027] The claimed sensor device includes sensor 1 and a corresponding remote station 11. Sensor device 10 is in... Figure 1 The diagram is shown in overview. The primary side includes a remote station 11; the secondary side includes a sensor 1. Sensor 1 communicates with both the remote station 11 and the upper-level unit 20, which are connected to the sensor 1 via interface 3. In this example, a transmitter is connected. The transmitter is in turn connected to a control system (not depicted). In an improved embodiment, sensor 1 communicates directly with the control system via the remote station 11. Cable 31 connects to the transmitter 20 on the sensor side, and its other end includes an interface 13 complementary to interface 3. The remote station 11 includes cable 31 along with interface 13.

[0028] Interfaces 3 and 13 are designed as current-isolated inductive interfaces, and they can be coupled to each other by means of a mechanical plug connection. Interfaces 3 and 13 thus form a primary coil and a secondary coil, wherein these terms are used complementaryly within the meaning of this document. The mechanical plug connection is sealed, so that no fluid, such as the measured medium, air, or dust, can enter from the outside.

[0029] Data is transmitted and received via interfaces 3 and 13 (bidirectional). Energy is transmitted unidirectionally, from the primary side to the secondary side via the primary and secondary coils. Sensor device 10 is primarily used for process automation.

[0030] Sensor 1 includes at least one sensor element 4 for acquiring measured variables for process automation (only in... Figure 1 (symbolically indicated and shown in the text). Sensor 1 is, for example, a pH sensor, also known as an ISFET, which is typically an ion-selective sensor used to measure redox potential, absorption of electromagnetic waves in a medium, such as in the UV, IR and / or visible light range, oxygen, conductivity, turbidity, concentration of non-metallic materials, or temperature with the corresponding measurement variable.

[0031] Sensor 1 includes a first coupler 2, which includes a first interface 3. For the purposes of this application, the interface is a secondary coil 3. The first coupler 2 is cylindrical and has an outer diameter of, for example, 12 mm.

[0032] As described above, the secondary coil 3 is designed to transmit values ​​dependent on the measured variable to the primary coil 13. The sensor 1 includes a data processing unit 6, such as a microcontroller, which processes the values ​​of the measured variables, for example, converting them into different data formats. This allows the data processing unit to perform averaging, preprocessing, and digital conversion. The sensor 1 includes a data memory containing persistent data of the sensor, particularly calibration data, serial numbers, tags, calibration values, and / or logs. Here, "persistent data" should be understood as data that "cannot be altered in an uncontrolled manner," i.e., data that remains (stored) even after the program or sensor 1 has been terminated (potentially even in unforeseen termination circumstances, such as power failure), and data that can be reconstructed and displayed again upon restarting the program.

[0033] The remote station 11 may also include a data processing unit, such as a microcontroller.

[0034] Sensor 1 can be connected to remote station 11 via interfaces 3 and 13, and ultimately to upper-level unit 20. As previously mentioned, upper-level unit 20 is, for example, a transmitter or control center. Data processing unit 6 converts the value of the measured variable into a protocol that can be understood by the transmitter or control center. Examples of this include, for example, proprietary Memosens protocols or HART, wirelessHART, Modbus, PROFIBUS Foundation Fieldbus, WLAN, ZigBee, Bluetooth, or RFID. This conversion can also be performed in a separate communication unit, rather than in the data processing unit, where the communication unit is located on one side of sensor 1 or on one side of remote station 11. The aforementioned protocols also include wireless protocols, so that the corresponding communication unit includes a wireless module. Interfaces 3 and 13 are therefore designed for bidirectional communication between sensor 1 and upper-level unit 20. As described above, sensor 1 is thus powered; see below.

[0035] The remote station 11 includes a data processing unit 16. The data processing unit 16 can be used as a repeater for transmitted signals. In addition, the data processing unit 16 can convert or modify protocols.

[0036] The remote station 11 also includes a second cylindrical coupler 12, which is designed to complement the first coupler 2 and can be inserted into the first coupler 2 using a sleeve-shaped end section, wherein an interface 13 is inserted into an interface 3. It is possible to have the interface 13 have a sleeve-shaped design and the interface 3 have a plug-shaped design in the opposite arrangement without any inventive steps. The second coupler 12 has at least partially a hollow cylindrical shape with an inner diameter of 12 mm.

[0037] Figure 2 Sensor 1 and remote station 11 with corresponding components are shown, with the corresponding sides indicated by dashed arrows.

[0038] As mentioned, sensor 1 is powered via interfaces 3 and 13. For this purpose, energy is transferred from the primary side to the secondary side through sensor 1. This ensures normal operation N. Furthermore, energy pulses can be transferred from the primary side to the secondary side, where additional energy is thus initially stored on the secondary side. Finally, the stored energy is transferred to one or more consumable components; see below.

[0039] Figure 3 The time-energy diagram is shown with time t, energy E, and energy pulse P transmitted in addition to normal operation.

[0040] Energy pulses are transmitted via event control, i.e., pulses are requested in a non-cyclic mode. Timing and control are processed via data processing units 6 and 16. The timing sequence of each step (see below) is therefore controlled via data processing units 6 and 16.

[0041] Typically, when the energy storage 7 is empty, a pulse P can be requested and sent. The energy storage 7 can also be charged shortly before energy is needed. Depending on the type of sensor, this may depend on the measurement value, such as during cleaning. Another possibility is when a particularly large amount of energy is required for measurement, because the measurement must be more accurate than usual (longer measurement time), or when the measurement occurs within a range that is not frequently used (e.g., high conductivity in the case of a conductivity sensor). These "events" are within the context of the application.

[0042] For this purpose, the primary side includes a power supply unit 15 for powering the sensor 1. The power supply unit 15 may be, for example, a transmitter 20, which thus forms part of the secondary side. The power supply unit 15 may also be a power supply unit that depends accordingly on the energy network.

[0043] The primary coil 13 is connected to the power supply unit 15.

[0044] The data processing unit 16 controls and (if applicable) regulates the transmission of energy for normal operation. Furthermore, it is designed to generate, control, and, where appropriate, regulate energy pulses P via energy source 15, and transmit energy pulses P to the secondary coil 3 with sensor 1. The system on the primary side is thus placed in a mode that generates a higher voltage than in normal operation.

[0045] Depending on the type of energy source 15, the primary side includes energy storage 17, i.e., one or more capacitors, for example. This is particularly advantageous or necessary when energy source 15 cannot provide sufficient energy for pulse P and therefore can buffer the energy required by pulse P.

[0046] The primary side includes a control element 18, specifically a transistor, for interacting with an energy source 15 and an optional energy storage 17 to generate energy pulses. By switching the control element 18, the primary side is placed in an increased energy transfer mode.

[0047] On the primary side, one or more capacitors are arranged next to the primary coil 13 (not shown; possibly in addition to the energy storage 17). The coil and (one or more) capacitors form a resonant circuit. The resonant circuit is altered by a control element 18, wherein one or more additional components, particularly one or more additional capacitors, are switched on by means of the control element 18.

[0048] The secondary side is then placed in a mode capable of receiving pulse P, meaning the energy pulse is transmitted, for example, to the energy storage device or directly to the consumable device via control element 8. Control element 8 on the secondary side, for example, ensures a reduction in the load on the secondary side. Although communication is thus interrupted during the duration of pulse P, energy transfer is increased.

[0049] Therefore, energy is systematically transferred from the primary side to the secondary side, and data is transmitted bidirectionally in principle. Sensor 1 collects measurement data, i.e., the measured variable in process automation technology. This data, depending on the value of the measured variable, is then transmitted from the secondary side to the primary side.

[0050] Then, when an event occurs, an energy pulse P is requested from the secondary side to the primary side, indicating a need for more energy. In an improved scheme, the acquisition of the measured variable is then interrupted. The transmission then depends on the value of the measured variable. Furthermore, at least one energy pulse P is transmitted from the primary side to the secondary side, wherein the energy pulse P is transmitted in an event-controlled manner.

[0051] Finally, return to normal mode, which means restarting the acquisition of the measured variable and transmitting the value depending on the measured variable to the primary side.

[0052] Initially, at least one voltage limiter 5 for limiting the input voltage at the secondary coil 3 is connected downstream of the secondary coil 3.

[0053] Depending on the type of sensor, additional energy from pulse P can be used directly. For example, a sensor that only occasionally needs to be cleaned using an ultrasonic actuator requires a relatively large amount of energy to complete this action. The actuator can then be operated directly during a higher energy transfer, without the need for temporary energy storage.

[0054] In one improved embodiment, the sensor 1 includes at least one energy storage 7, which is optionally connected to the secondary coil 3 via a voltage limiter 5, wherein the energy storage stores at least energy from the energy pulse P.

[0055] Energy storage 7 comprises one or more capacitors, such as multilayer chip capacitors. This can also be achieved by using one or more capacitors connected in parallel. Energy is stored by charging the capacitors to a (temporarily) increased input voltage. A reasonable amount of energy here is 10mJ to 20mJ. The capacitors are charged here to the maximum possible input voltage (see voltage limiter 5, e.g., approximately 15-35V, especially 20V). This amount of energy can still be transferred / charged for a sufficiently short time. Typical pulse durations are, for example, 50-250ms, especially 100ms. During the remaining time (e.g., 100-750ms, especially 300ms intervals), the stored energy can be used, and sensor 1 can be operated in normal operation N. Capacitor 7 is arranged after rectification by the limiter on the secondary coil 3 or the secondary side. Rectification can be simple rectification or bridge rectification.

[0056] The storage capacitor 7 is isolated from the rest of the input circuit (particularly from the data processing unit 6 and sensor element 4) by an isolation circuit 9 (e.g., a diode). This isolation prevents the capacitor 7 from acting as an additional capacitive load during normal operation N. If the capacitor 7 does not discharge below the rated input voltage, no current flows to the capacitor during rated operation.

[0057] The discharge process is ultimately carried out via regulator 35, which is, for example, a linear regulator or a switching regulator, particularly a buck regulator, such as a DC / DC converter.

[0058] For the increased input voltage of pulse P, the storage capacitor 7, regulator 35, and other components of the rest of the power supply circuit must be designed accordingly.

[0059] The discharge / power output can be controlled by the data processing unit 6 via the control input or feedback input on the regulator 35.

[0060] The state of charge of the storage capacitor 7 can be measured optionally via an analog-to-digital converter of the data processing unit 6 (optionally having an upstream voltage divider).

[0061] Sensor 1 includes at least one consumable component connected to energy storage 7. Here, "consumable component" may be, for example, data processing unit 6, sensor element 4, or cleaning unit. If there is no storage, the consumable component will be connected to primary coil 13.

[0062] Time-based functional mechanisms facilitate the operation of this principle:

[0063] The charging cycle is timed in sensor device 10. Microcontrollers 6 and 16 are used to control these processes.

[0064] When the energy storage charging phase begins, the secondary circuitry minimizes its own power consumption. Therefore, a high input voltage can potentially be achieved while losses due to inherent input current remain low. The primary side increases the transmitted voltage to its maximum value. Ideally, the voltage on the primary side is increased to such an extent that it precisely corresponds to a voltage limit measure that has not yet responded. As a result, maximum energy storage is achieved, yet there are no significant losses via the limiting element. Considering that losses increase significantly when the voltage rises above the limiting voltage, the system is self-limiting within a certain range. During the discharge process, i.e., during the use of the stored energy on the secondary side, the sensors and cables return to normal mode. Communication is also possible again during this period.

[0065] The energy stored in capacitor 7 can be supplied to the application via regulator 35 (linear or switching regulator). Therefore, a larger input current can be provided, thereby enabling higher performance through the application. The only condition for this application is that the power supply circuitry is designed for the brief voltage spikes that occur during charging. As mentioned above, a cleaning device, such as an ultrasonic actuator, is considered an "application." Further possibilities include, for example, a motor for moving another component, such as a wiper for cleaning surfaces (like optical windows), or switching the sensor itself to a state with increased power consumption. This occurs, for example, when measurements must be more accurate than usual (longer measurement times) or are performed within measurement ranges that are not used regularly (e.g., the high conductivity of a conductivity sensor).

[0066] List of reference numerals

[0067] 1. Sensor

[0068] 2 Coupler

[0069] 3 Secondary coils

[0070] 4. Sensor Components

[0071] 5. Voltage Regulator

[0072] 6 Data Processing Unit

[0073] 7. Energy Storage

[0074] 8 Control Components

[0075] 9. Isolation circuit

[0076] 10 Sensor Devices

[0077] 11 Remote Station

[0078] 12 Couplers

[0079] 13 Primary coil

[0080] 15 Power Supply Units

[0081] 16 Data Processing Units

[0082] 17 Energy Storage

[0083] 18 Control elements

[0084] 20. Upper-level unit

[0085] 31 Cable

[0086] 35 Controller

[0087] t time

[0088] E energy

[0089] N Normal operation

[0090] P energy pulse

Claims

1. A method of transferring energy to a sensor (1), the method comprising the steps of: - transferring energy from a primary side to a secondary side, wherein the sensor (1) is arranged on the secondary side, wherein the primary side and the secondary side are coupled to each other via a primary coil (13) and a secondary coil (3) and the energy is transferred by means of both coils (3, 13), wherein the primary coil (13) and the secondary coil (3) are thereby designed to transmit data bidirectionally, - acquiring a measured variable by means of the sensor (1), - transferring a value dependent on the measured variable from the secondary side to the primary side, - requesting an energy pulse (P) from the secondary side to the primary side when an event occurs that requires more energy, - interrupting the transfer of the value dependent on the measured variable, - transferring at least one energy pulse (P) from the primary side to the secondary side, wherein the energy pulse (P) is transferred in an event-controlled manner, and - returning to the normal mode, re-acquiring the measured variable and transferring a value dependent on the measured variable to the primary side.

2. The method according to claim 1, comprising the step of: - storing additional energy from the energy pulse (P) on the secondary side.

3. A sensor arrangement (10) for transferring energy to a sensor (1) to perform the method according to any one of claims 1-2, the sensor arrangement (10) comprising: - a primary side, the primary side comprising: ■a power supply unit (15), ■a primary coil (13) connected to the power supply unit (15) and designed to transfer energy and energy pulses (P) to a secondary coil (3) and to transmit or receive data bidirectionally, and ■a first data processing unit (16) designed to control and optionally regulate the transfer of energy, and the first data processing unit (16) is designed to generate, control, in appropriate cases regulate, and transfer energy pulses (P) to the secondary coil (3) by means of the power supply unit (15), and - a secondary side with a sensor (1), the sensor (1) comprising: ■a secondary coil (3) designed to receive energy and energy pulses (P) from the primary coil (13) and to transmit or receive data bidirectionally, ■at least one voltage limiter (5) for limiting the input voltage at the secondary coil (3), wherein the voltage limiter (5) is connected to the secondary coil (3), ■a sensor element (4) for acquiring at least one measured variable, and ■a second data processing unit (6) connected at least to the sensor element (4) and to the secondary coil (3), wherein the second data processing unit (6) is designed to generate data related to the measured variable.

4. The sensor device (10) according to claim 3, comprising: - at least one energy storage (7) on the secondary side, which is connected to the secondary winding (3), which stores at least energy from the energy pulse (P).

5. The sensor device (10) according to claim 3 or 4, comprising: - an energy storage (17) on the primary side.

6. The sensor device (10) according to claim 3 or 4, comprising: - a control element (18) on the primary side for generating the energy pulse (P).

7. The sensor device (10) according to claim 6, wherein, the control element (18) on the primary side comprises a transistor.

8. The sensor device (10) according to claim 4, comprising: - a control element (8) on the secondary side for delivering the energy pulse to the energy storage (7) or to a consumer.

9. The sensor device (10) according to claim 8, wherein the control element (8) on the secondary side comprises a transistor.

10. The sensor device (10) according to claim 4, comprising: - a regulator (35), which is connected downstream of the energy storage (7) on the secondary side.

11. The sensor device (10) according to claim 10, wherein the regulator (35) comprises a linear regulator or a switching regulator.

12. The sensor device (10) according to claim 10, wherein the regulator is designed as a step-down regulator.

13. The sensor device (10) according to claim 4, comprising: - an isolation circuit (9), which is connected between the energy storage (7) and the sensor element (4).

14. The sensor device (10) according to claim 13, wherein the isolation circuit (9) comprises at least one diode.

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