Method and device for controlling the power supply of a field device

Abstract

The invention relates to a device and a method for controlling the power supply of a field device (100). The device comprises a rechargeable energy storage device (140), a load (160), and a first switch (144) between the energy storage device (140) and the load (160). Furthermore, the device comprises a solar cell (120) with a cover (121) configured to block light from entering the solar cell (120), thereby switching the field device (100) from normal operation to shipping mode and opening the first switch (144).

Description

Technical field

[0001] The invention relates to a device and a method for controlling the power supply of a field device. Furthermore, the invention relates to a field device and its use. background

[0002] Field devices, especially so-called autonomous field devices, often incorporate an energy storage device, and in at least some cases, a rechargeable one. In at least some of these energy storage devices, chemical decomposition can begin if the voltage falls below a certain threshold. This chemical decomposition can be irreparable. Summary

[0003] The object of the invention is to provide a method that contributes to at least delaying the chemical decomposition of the energy storage medium. This object is achieved by the subject matter of the independent claims. Further developments of the invention are described in the dependent claims and the following description.

[0004] One aspect concerns a device for controlling the power supply of a field device. The device includes a rechargeable energy storage device, a load, and a first switch between the energy storage device and the load. Furthermore, the device includes a solar cell with a cover designed to block light from the solar cell, thereby switching the field device from normal operation to shipping mode and opening the first switch.

[0005] The field device can be used, for example, for level measurement and / or other applications. If the field device is used for level measurement, it may include a power consumer. This consumer could include, for example, a level sensor, an evaluation unit, a display, a radio module, and / or other components. The field device can also be a self-contained device that is powered exclusively by its own energy storage system during operation. This energy storage system can be rechargeable, for example, a battery or capacitor.

[0006] The first switch, located between the energy storage device and the load, can be designed as a mechanical and / or electronic switch. This first switch turns the load on and off. A sub-circuit, such as one that monitors the energy storage device's voltage, may not be switchable by this first switch, meaning it remains "always on" and / or functional. This sub-circuit may be an independent circuit or part of a larger circuit where large sections can be switched off and / or put into a "deep sleep" state.

[0007] The field device may include an energy source, in particular a solar cell, which – as an “internal” energy source – is arranged in, on, or near the field device to supply energy to the energy storage device and / or the consumer, i.e., to transfer electricity to the energy storage device and / or the consumer. The “internal” energy source may provide energy to the field device exclusively or in combination with another (“external”) energy source.

[0008] The solar cell has a cover designed to block out light. Covering the solar cell not only stops energy production but also puts the field device from normal operation into shipping mode. Shipping mode is a state in which the field device can be stored or shipped, for example, and in which its normal function—such as taking measurements—is not required. Shipping mode can be optimized to at least delay the chemical degradation of the energy storage device. This can be achieved, for example, by switching off almost all functions of the field device that draw power from the energy storage device. A sub-circuit that monitors the energy storage device's voltage may still be functional.Furthermore, it is also possible to interrupt the connection to the solar cell, as the energy storage can also be discharged via the solar cell.

[0009] One aspect concerns a method for controlling the power supply of a field device, wherein the field device comprises a device as described above and / or below. The method comprises the following steps: In normal operation, closing the first switch so that the consumer draws power from the solar cell and / or from the energy storage device; transitioning to a shipping mode by covering the solar cell opaquely with the cover; in the shipping mode, opening the first switch; transitioning to normal operation by opening the cover of the solar cell; and in normal operation, closing the first switch.

[0010] In normal operation, the field device, depending on its design, can perform tasks such as topology determination, level determination, flow measurement, pressure measurement, and / or temperature measurement. For this purpose, a first switch between the energy storage device and the load is closed, allowing the load to draw power from the solar cell and / or the energy storage device. Covering the solar cell with an opaque cover initiates a transition to shipping mode. Upon or after this transition to shipping mode, the first switch opens. This first switch can be, for example, a mechanical and / or electronic switch. This switches off the load. In this way, virtually all functions of the field device that draw power from the energy storage device can be deactivated.A sub-circuit that monitors the voltage of the energy storage device may still be functional. This can significantly delay the chemical degradation of the energy storage device. As a result, the field device can advantageously be stored for longer periods and / or withstand longer shipping times without damage.

[0011] In some embodiments, during normal operation, when a first predefined voltage of the energy source is exceeded, current is transferred from the solar cell to the energy storage device by closing a second switch. The first predefined voltage can be a threshold above which the energy storage device can be charged. The second switch is located between the solar cell and the energy storage device. The second switch can be a mechanical switch, an electronic switch (e.g., a MOSFET), or a comparable semiconductor. Alternatively or additionally, the second switch can be implemented by a diode between the solar cell and the energy storage device, so that the energy storage device is always charged when the voltage of the solar cell is higher than the voltage of the energy source plus the diode voltage. In some embodiments, the diode is implemented as a low reverse current diode, particularly a Schottky diode.This makes it particularly effective to prevent the energy storage device from discharging towards the energy source.

[0012] In some embodiments, the second switch can advantageously be used to interrupt the connection to the solar cell, since the energy storage device can also be discharged via the solar cell. The connection to the solar cell can be established, for example, in shipping mode, when the first predefined voltage of the energy source is exceeded, and / or by manually actuating the second switch.

[0013] In some embodiments, when the power source voltage falls below a second predefined threshold in Shipping Mode, a visual and / or audible warning is issued. The visual warning can be, for example, a low-power red LED or a message displayed on a low-power screen, such as an e-paper or e-ink display. The audible warning can be, for example, a buzzer. If the field device has a radio module, an electronic message—such as an SMS—can be sent, alternatively or additionally, to the manufacturer and / or a warehouse management system.

[0014] In some embodiments, the opening and / or closing of the first switch is effected by opening the cover using an electronic or magnetic component, in particular a reed relay. This can be achieved, for example, by mechanically connecting the first switch to the cover, and / or by having the cover, for example, a permanent magnet that is magnetically connected to the first switch. These embodiments can advantageously be particularly robust and / or simple.

[0015] In some embodiments, the opening and / or closing of the first switch is achieved through manual interaction. This can be done, for example, by pressing a button to manually trigger shipping mode when needed. Alternatively or additionally, manual interaction can be achieved by setting a parameter (e.g., "Set Shipping Mode") in the field device settings.

[0016] In some embodiments, the first switch is implemented as a FET, in particular as a MOSFET, or as a relay, in particular as a reed relay.

[0017] In some implementations, the transition to shipping mode occurs after a predefined delay. This delay can be adjustable. For example, it can be zero seconds, one minute, or one hour. The adjustable delay allows for the absorption of short-term events such as shading, sunlight, or covering.

[0018] In some embodiments, the energy storage device is designed as an accumulator, a battery, or a capacitor, in particular a lithium-hybrid capacitor. Alternatively or additionally, the accumulator can also be designed as another type of accumulator, for example, a lithium-ion accumulator, another type of lithium-based accumulator, or another type of battery.

[0019] One aspect concerns a field device that includes a device for controlling a power supply as described above and / or below.

[0020] One aspect concerns the use of a field device as described above and / or below for level measurement, topology determination, limit level determination, flow measurement, pressure measurement and / or temperature measurement.

[0021] It should also be noted that the various embodiments described above and / or below can be combined with each other.

[0022] For further clarification, the invention is described with reference to embodiments illustrated in the figures. These embodiments are to be understood as examples only, and not as limitations. Brief description of the characters

[0023] This shows: Fig. 1 schematically a field device according to one embodiment; Fig. 2 a state diagram with a method according to an embodiment. Detailed description of embodiments

[0024] Fig. Figure 1 schematically shows a field device 100 according to one embodiment. The field device 100 has a rechargeable energy storage device 140. The rechargeable energy storage device 140 can be, for example, a rechargeable battery, a standard battery, or a capacitor. The field device 100 can also have an "external" energy source (not shown), which can be connected, for example, via a two-wire connection. Furthermore, the field device 100 has a load 160. Depending on the embodiment of the field device 100, the load 160 can, for example, include a level sensor, an evaluation unit, a display, a radio module, and / or other components. The field device 100 has a first switch 144 between the energy storage device 140 and the load 160. The field device 100 also has an energy source 120, which can be, in particular, a solar cell. The field device 100 has a cover 121 that is arranged over the solar cell 120.The cover 121 can be used to make the solar cell opaque, thereby switching the field device from normal operation to shipping mode and opening the first switch 144. Opening the first switch 144 can be achieved via a control line or coupling 142. The coupling 142 can be implemented electronically or magnetically, for example, by a push button or by a permanent magnet in or on the cover 121.

[0025] The field device 100 from Fig. The device also features a second switch 124, which is arranged between the solar cell and the energy storage device. In normal operation, when a first predefined voltage of the energy source 120 is exceeded, current is transferred from the solar cell 120 to the energy storage device 140 by closing the second switch 124. The second switch can be a mechanical switch, an electronic switch (e.g., a MOSFET), or a comparable semiconductor. Alternatively or additionally, the second switch can be implemented by a diode between the solar cell and the energy storage device, so that the energy storage device is always charged when the voltage of the solar cell is higher than the voltage of the energy source plus the diode voltage. In shipping mode, the second switch 124 can be opened to interrupt the connection to the solar cell 120, since the energy storage device 140 can also be discharged via the solar cell 120.

[0026] Fig. Figure 2 shows a state diagram 200 with a method according to one embodiment. In normal operation (state "Normal"), the first switch 144 (see Fig.1) Closed, so that the consumer 160 draws power from the solar cell 120 and / or from the energy storage device 140. A transition to shipping mode occurs when the solar cell 120 is covered opaquely with the cover 121. Alternatively or additionally, the transition to shipping mode can be initiated manually. In shipping mode, the first switch 144 is opened. This switches off the consumer 160 – and thus all of its functions. A sub-circuit (not shown) that monitors the voltage of the energy storage device 140 may remain functional even after the first switch 144 is opened. As long as the cover 121 is closed and the solar cell 120 is not producing power, the field device remains in shipping mode. Opening the cover 121 of the solar cell 120 returns the device to normal operation.In normal operation, the first switch 144 is closed. List of reference symbols 100 field devices 120 solar cells, energy source 121 Cover of the solar cell 122 Control line 124 second switch 140 energy storage units 142 Control line 144 first switch 160 consumers 200 State diagram

Claims

[1] Device for controlling a power supply of a field device (100), comprising the device: a rechargeable energy storage device (140); one consumer (160), a first switch (144) between the energy storage device (140) and the consumer (160), and a solar cell (120) which has a cover (121) which is designed to cover the solar cell (120) in an opaque manner and thereby switch the field device (100) from normal operation to shipping mode and open the first switch (144). [2] Method for controlling a power supply of a field device (100), the field device (100) comprising a device according to claim 1, the method comprising the steps: in normal operation, closing the first switch (144), so that the consumer (160) draws power from the solar cell (120) and / or from the energy storage device (140); by covering the solar cell (120) opaquely with the cover (121), transitioning into a shipping mode; in Shipping Mode, open the first switch (144); by opening the cover (121) of the solar cell (120), transition to normal operation; and In normal operation, closing the first switch (144). [3] Method according to claim 2, with the further step of: In normal operation, when a first predefined voltage of the energy source (120) is exceeded, current is transferred from the solar cell (120) to the energy storage device (140) by closing a second switch (124). [4] Method according to claim 2 or 3, further comprising the step: In Shipping Mode, if the voltage of the energy source falls below a second predefined level (120), an optical and / or acoustic warning is issued. [5] Method according to one of claims 2-4, wherein the opening and / or closing of the first switch (144) is effected by opening the cover (121) by means of an electrical or magnetic component, in particular by means of a reed relay. [6] Method according to any one of claims 2-5, wherein the opening and / or closing of the first switch (144) is carried out by manual interaction. [7] Method according to one of claims 2-6, wherein the first switch (144) is implemented as a FET, in particular as a MOSFET, or as a relay, in particular as a reed relay. [8] Method according to one of claims 2-7, wherein the transition to shipping mode takes place after a predefined delay time, wherein the predefined delay time is adjustable and is, for example, zero seconds, one minute or one hour. [9] Method according to one of claims 2-8, wherein the energy storage device (140) is designed as an accumulator, as a battery or as a capacitor, in particular as a lithium hybrid capacitor. [10] Field device (100) comprising a device for controlling a power supply according to claim 1. [11] Use of a field device (100) according to claim 10 for level measurement, topology determination, limit level determination, flow measurement, pressure measurement and / or temperature measurement.

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