WO2007039230A1 - Capacitative energy transmission between capacitively coupled components - Google Patents

Abstract

The invention relates to an energy supply system for a device, said energy supply system comprising a first circuit part (101), a second circuit part (102) and a capacitative coupling unit. The first circuit part is galvanically separated from the second circuit part by means of the capacitative coupling unit (109, 110). The capacitative coupling unit can be used to capacitively inject electrical energy from the first circuit part into the second circuit part.

Description

 Capacitive energy transfer between capacitively coupled components

Related applications

The present application claims priority to US Provisional Patent Application No. 60 / 723,857 filed October 5, 2005 and German Patent Application No. 10 2005 047 611.2 filed October 5, 2005, the contents of which are hereby incorporated by reference.

Technical area

The invention relates to a power supply device, an interface device, a field device arrangement and a method for supplying a device with energy, in particular with electrical isolation between a field device and an operating device.

Background of the invention

For measuring the level of liquids and solids in containers from the use of measurement of propagation time of electromagnetic waves measuring devices are usually mounted on or in the container wall. The measuring device then sends waves, either guided through a waveguide or radiated via an antenna, in the direction of the medium. The waves reflected on the medium are then received again by the measuring device. The distance between the sensor and the filling material, and from the knowledge of the position from the sensor to the bottom of the container, results in the filling level sought from the determined running time.

In measurement technology, it is common for field devices (for example, a level measuring device) to convert process variables into electrical signals and to be connected to other devices via bus systems. This allows the measurement signals recorded by the field devices to be transmitted over a greater distance transferred to other devices. A common technique for connecting field devices to other devices is the so-called HART bus standard, a Profibus or an FF ("Foundation Fieldbus").

Such a level gauge can be arranged in a potentially explosive environment, for example in an oil tank. Such a level gauge can exchange data with a central control unit, for example a PC. In this case, arcing due to the compensation of potential differences in potential to be avoided by flowing potential equalization currents, as this can be dangerous in a potentially explosive environment or damage or destroy equipment.

It is possible to achieve an energy transfer between two elements in a potentially explosive environment or even outside a potentially explosive environment using transformers. A transformer having coils operatively connected to one another may transmit an alternating electrical signal. In such an electrical alternating signal energy can be contained and thus transmitted.

A full bridge converter, which is suitable for energy transmission between two separate components by means of a transformer, is known from Udo Leonhard Thiel, "switching power supplies", 2nd edition, Franzis Verlag, pages 74 and 75. Through a switch, an AC voltage can be generated from a DC voltage, which is transmitted by a transformer from a primary side to a secondary side, then rectified and is then available on the secondary side as an energy source. Since in a transformer arrangement, the geometric distance between the primary and the secondary side in many cases is not sufficiently large due to the coupled coils, the onset of an inductive coupling in a hazardous environment or outside can be problematic because potential equalization currents can occur. Nevertheless, is an inductive

Coupling element as a power transmission unit due to the need for the provision of the coils and other components in terms of dimensions too large to be suitable for a miniaturized arrangement.

It is an object of the present invention to provide an efficient

Provide power supply device for a device.

Accordingly, a power supply device, an interface device, a field device arrangement, and a method for supplying a device with energy having the features according to the independent claims are provided.

According to an exemplary embodiment of the invention, a power supply device for a device is provided, wherein the power supply device has a first circuit part, a second circuit part

Circuit part and a capacitive coupling unit, wherein the first circuit part of the second circuit part by means of the capacitive coupling unit is electrically isolated and wherein by means of the capacitive coupling unit electrical energy from the first circuit part in the second circuit part can be coupled capacitively.

According to another exemplary embodiment of the invention, an interface device is provided for coupling a control device to a field device, wherein the interface device comprises a power supply device the features described above for supplying the device with electrical energy, wherein the device comprises the interface device and / or the control device and / or the field device.

According to another exemplary embodiment of the invention, a field device arrangement is provided, which has a field device and an interface device with the features described above for coupling a control device to the field device.

According to yet another exemplary embodiment of the invention, there is provided a method of powering a device, wherein in the method a first circuit part is or is galvanically isolated from a second circuit part by means of a capacitive coupling unit, and electrical energy from the first circuit part in FIG the second circuit part is capacitively coupled by means of a capacitive coupling unit.

According to an exemplary embodiment of the invention can thus be operated safely by providing a galvanic isolation between two components to be coupled a potentially explosive environment or a non-hazardous environment. Simultaneously, power can be supplied by transmitting electrical signals across a capacitive coupling element, using the energy contained in the transmitted electrical signals as the source of energy. Due to the capacitive separation of the two circuit parts can thus

Sparks jump or the flow of equipotential bonding currents between the two circuit parts can be avoided, and simultaneously can capacitively an electric (alternating) current (which can also be referred to as "signal" and may optionally contain information) to be transmitted in this Signal used to supply energy to one of the coupled circuit parts or other, associated device.

According to the invention, an undesired or impermissible flow of equipotential bonding currents due to the galvanic isolation and the capacitive coupling element can be avoided so that involved devices can be safely protected against possible damage or destruction.

In the case of a capacitance or a capacitor as a capacitive coupling element, it may be advantageous that the spacing of the capacitor plates or of the two electrically conductive capacitor elements can be selected to be sufficiently large that reliable decoupling can be ensured as explosion protection and at the same time an efficient energy transmission can be made possible. Nevertheless, the dimension of such an arrangement - due to the dispensability of a transformer - can be chosen sufficiently small that a miniaturized arrangement is obtained, which meet with respect to the transferable energy requirements, for example, an interface device for coupling a control device with a field device. This provides an energy transfer capability that can be used, for example, in an environment in which level gauges, pressure gauges or other field devices are to be operated in an explosive environment.

Illustratively, according to the invention, an energy transfer between two circuit parts can not be realized by means of a transformer, but with the interconnection of capacitances, which enables a particularly small-dimensioned yet powerful operation. Also, a DC signal, for example using appropriately timed switches, can be clearly chopped to generate a pulse train or an alternating signal, which can then be transmitted capacitively. After a rectification of the transmitted signal is then possibly even a direct current signal for supplying a device with electrical power ready.

According to one embodiment of the invention, a transmission of sufficiently high electrical powers is possible, for example in the mW range. In the embodiment of the capacitive coupling element as a capacitor bank, for example as an arrangement of parallel connected capacitors, a capacitive coupling can be amplified and thus the transmittable energy can be increased due to the additive effect of the correspondingly interconnected individual capacitances.

For example, this principle of power supply using capacitive power transfer in combination with galvanic isolation may be used for an interface converter to couple a control computer to a level sensor. For example, such a control computer can communicate with such an interface device via a USB interface

Interface converter may be coupled, which interface converter can communicate with a level sensor, for example, according to the HART protocol or the I2C standard. Alternatively, it is also possible for such an interface converter to communicate wirelessly ("wirelessly") with the control device and / or with the field device, for example by means of wireless LAN or Bluetooth.

In the interface converter, both the galvanic separation as explosion protection and the energy transfer in capacitive ways be realized so that, for example, the interface converter and / or the level sensor can be powered by this energy transfer concept with energy or can.

In other words, in such an interface converter, two galvanically isolated circuit parts can be included, which transfer capacitive energy, which is supplied for example by a battery or a power supply of the connected computer.

For example, at a voltage of 5 volts, a current of up to 100 mA, up to 500 mA and more, can be transferred via a USB interface ("Universal Serial Bus").

In a potentially explosive environment, it may be advantageous to galvanically separate units that communicate with each other. In the context of this application, the term galvanic separation is understood in particular to mean that there is no coherent, ohmic conductive path between the units communicating with one another via which charge carriers can flow from one of the units into one of the units that is galvanically separated. The ohmic decoupling of two galvanically separated circuits allows them to be used in a potentially explosive environment or outside of it.

The first circuit part and the second circuit part can either be hard-wired, that is to say implemented using macroscopic electronic components or else as an integrated circuit. In particular, the energy transmission system can be both by means of a computer program, that is, a software and by means of one or more special electrical circuits, that is, in hardware, or in any hybrid form, that means using software components and hardware components.

For example, according to the invention, a power transmission circuit for power transmission between a first terminal and a second

Connection can be created, which connections are galvanically isolated from each other. The energy may be transferable between the first terminal and the second terminal, for example by capacitive coupling. The capacitive coupling does not exclude ohmic and / or inductive transmission components.

The capacitance of the capacitive coupling unit may be on the order of 100 nF, for example. A chopping frequency, that is, a frequency of a time series of pulses or waves, may be on the order of 600 kHz or 630 kHz, for example. Considerably larger capacities can also be used, provided that an explosion limitation is observed.

Exemplary embodiments of the invention will become apparent from the dependent claims.

In the following, embodiments of the power supply device will be described. These embodiments also apply to the interface device, the field device arrangement and the method for supplying a device for operation in a potentially explosive environment with energy.

In the power supply device, the first circuit part can have an electrical energy source that is set up to provide a time-varying electrical potential. This energy source can For example, be a battery or a power supply that can deliver a DC voltage and / or an AC voltage. As an energy source can also serve a connected to the power supply element, for example, a connected to a power supply computer, which is connected via a cable to a power supply device.

The electrical energy source may be an electrical AC voltage source. This is advantageous because then the electrical AC energy directly, that is, without intermediate processing, can be transmitted by the capacitive coupling unit.

In contrast, a capacitive circuit element has an infinitely high resistance for a pure DC voltage. Nevertheless, the power supply device according to the invention can also be operated with an electrical DC voltage source as an electrical energy source. In this case, a switching unit may be provided in the energy supply device, wherein by means of the switching unit, a temporally constant electrical potential provided by the electrical DC voltage source is converted into the time-varying potential. For example, transistors may be interconnected to a switching unit, which are clocked by, for example, clock control. In this way, a direct electrical voltage can be converted into an alternating signal, wherein the frequency of the alternating voltage generated thereby based on the chopping frequency of the DC voltage. In this way, the capacitive energy transmission according to the invention can also be realized by using a DC voltage source, such as a battery.

The switching unit may comprise a transistor or may have a transistor circuit, driven by means of a clock. The transistor can be a Be bipolar transistor or a field effect transistor, for example, an n-MOSFET or a p-MOSFET.

The capacitive coupling unit may comprise at least one element from the group consisting of a capacitor, a capacitor bank, a series connection of at least two capacitors and / or a parallel connection of at least two capacitors. By interconnecting a plurality of capacitors, the realizable effective capacity can be increased. When using sufficiently large capacitors, a large capacity can also be achieved. On the other hand, it may be advantageous to make the capacitors small and instead prefer to provide a plurality of such capacitors to minimize the size of the overall system.

The capacitive coupling unit can be set up in such a way that a spark-over of an electrical signal across the capacitive coupling unit is avoided. For example, the power supply device can then be used in an explosive environment, for example when the fill level in an oil tank is to be measured and the sensor data is to be transmitted to an evaluation unit.

Components of the capacitive coupling unit (for example a capacitor) can have such a small capacitance that an explosion-triggering spark-over of an electrical signal across these components is avoided. In other words, the value of the capacity can be chosen so small that it can come to any explosion-triggering spark. In particular, the arrangement for this can also be operated in low load operation, for example, with a power in the milliwatt range. The second circuit part of the power supply device can have an electrical rectifier unit which is set up to rectify a time-varying electrical signal, which is capacitively coupled into the second circuit part by means of the capacitive coupling unit. If an AC voltage or a DC voltage converted by means of a switching element to an AC signal has been transmitted via the capacitive coupling unit into the second circuit part, it may be advantageous to generate a DC voltage as a power supply to make a DC signal from the AC signal with a rectifier circuit. For this purpose, for example, a diode or a diode circuit can be used, wherein in this case use can be made of the effect that a diode can be operated in a reverse direction and in a forward direction, so that only selectively certain components of an AC voltage can be transmitted, whereby a DC voltage can be tapped.

By means of a smoothing capacitor, the rectified by a rectifier circuit signal can be smoothed.

The first circuit part may have a first branch and a second branch connected in parallel with the first branch, wherein the second circuit part may have a third branch and a fourth branch connected in parallel with the third branch. The first branch may be capacitively coupled to the third branch and the second branch may be capacitively coupled to the fourth branch by means of the capacitive coupling unit. In other words, it may be advantageous to use both the first circuit part and the second one

To realize circuit part by using two parallel paths or branches. Then, a respective branch of the first circuit part can be coupled to an associated branch of the second circuit part. The first branch may be capacitively coupled to the third branch by means of a first capacitor of the capacitive coupling unit, and the second branch may be capacitively coupled to the fourth branch by means of a second capacitor of the capacitive coupling unit. By providing two branches both on the primary side and on the secondary side of the combined galvanic separation and capacitive energy recovery system, in particular a more uniform DC voltage can be realized on the secondary side.

The device may comprise at least one element from the group consisting of an interface device for coupling a control device and a field device, a control device for controlling a field device via an interface device, and a field device controllable by means of a control device via an interface device.

A field device may be, for example, a level gauge or a pressure sensor. A controller may be, for example, a computer (eg, PC, server computer, laptop, handheld device, programmer, etc.) that may be provided for driving and reading a field device.

An interface device can, for example, mediate between such a control device and a field device, in particular provide galvanic isolation and / or enable format conversion or conversion of transmitted signals. For example, a control device can be controlled via a USB interface, which can be coupled to a first input of such an interface device, and a second input of such an interface device can, for example, signals according to a standard understandable for the field device (for example, HART or I2C). provide. The conversion of these signal formats can be done by the interface device.

It may also be necessary, for example, to access a field device with a programming device in order to calibrate it, to control it or to read out signals from the field device.

By means of the capacitive coupling device, the electrical energy from the first circuit part in the second circuit part can be coupled purely capacitive. In other words, the physical nature of the energy injection from an ohmic and / or an inductive component can be completely free, so that a completely capacitive coupling can take place.

The power supply device can be configured to supply the device with energy for operation in a potentially explosive environment. However, the power supply device can also be set up to supply the device for operation in a non-hazardous environment with energy.

In the following, embodiments of the interface device will be described. These embodiments also apply to the power supply device, to the field device arrangement and to the method for supplying a device for operating a potentially explosive environment with energy.

The interface device may include a first port for connecting the controller, which may be a USB port. The controller may be a computer. In this way, the interface device can be set up for connection to a commercial PC, which thus with a connected field device can be operated. Thus, energy can be provided or transmitted via a USB bus.

Furthermore, the interface device can have a second connection, which can be set up for connection to the field device. For example, this second connection may be a HART connection or an I2C connection or a Profibus or a FF bus ("Foundation Fieldbus"), that is to say in particular a connection which permits transmission of signals according to the HART bus standard or the I2C protocol. Bus standard allows.

I2C or I ² C (for Inter-Integrated Circuit) is a serial bus for computer systems. It can be used to connect devices to an embedded system or motherboard. For example, I2C may be used in accordance with the present invention to facilitate communication of various devices over longer line connections.

In particular, the HART protocol ("Highway Addressable Remote Transmitter") may be referred to as an open master-slave protocol for bus-addressable field devices and may implement a method of frequency-shift keying (FSK) data superimposed on the 4-20mA process signal to transmit to enable remote configuration and diagnostics verification.

Both I2C and HART are useful as protocols for communicating with a field device, such as a level gauge or a pressure gauge.

In particular, the interface device can be set up as an interface converter, that is to say as a device which has a format of the data between the interface for connecting the control device and the interface to the interface Connecting the field device allows. In this way, two devices based on completely different standards, namely control unit and field device, can communicate with each other when an interface device according to the invention is interposed as a "translator".

In the following, embodiments of the field device arrangement will be described. These embodiments also apply to the power supply device, to the interface device and to the method of powering a device for operation in a potentially explosive environment.

The field device arrangement may be a level gauge or a pressure gauge. However, there are other ways to design such a field device, for example as any type of sensor or actuator, in particular controlled by an associated control unit.

Exemplary embodiments of the invention are illustrated in the figures and will be explained in more detail below.

Show it:

Fig. 1 shows a power supply device according to an exemplary

Embodiment of the invention.

2 shows a field device arrangement according to an exemplary embodiment of the invention.

Fig. 3 shows a field device arrangement according to an exemplary

Embodiment of the invention. 4 shows a field device arrangement according to an exemplary embodiment

Exemplary embodiment of the invention, which is connected with FIG.

5 shows a partial area of a field device arrangement according to an exemplary embodiment of the invention.

Fig. 6 shows a power supply device according to an exemplary

Exemplary embodiment of the invention.

Fig. 7 shows a power supply device according to an exemplary

Embodiment of the invention.

Fig. 8 is a circuit diagram of an interface device according to an exemplary embodiment of the invention.

The same or similar components in different figures are provided with the same reference numerals.

The illustrations in the figures are schematic and not to scale.

In the following, a power supply device 100 according to an exemplary embodiment of the invention will be described with reference to FIG.

1 shows a power supply circuit 100 for supplying a load 103 with electrical energy, wherein the load 103 may be located in an explosive environment (for example, in a level sensor of an oil tank). The power supply circuit 100 has a first circuit part 101 and a second circuit part 102, as well as a capacitive coupling unit 104.

The first circuit part 101 is galvanically isolated from the second circuit part 102 by means of the capacitive coupling unit 104. There may be provided further galvanic separation elements, that is, capacitive decoupling between the two circuit parts 101, 102, which avoid a direct flow of electric current between these two circuit parts 101, 102. By means of the capacitive coupling unit 104, electrical energy can be capacitively coupled from the first circuit part 101 into the second circuit part 102, wherein this energy can then be used to supply the load 103 with direct electrical voltage energy.

The first circuit part 101 has an electrical energy source that is set up to provide a time-varying electrical potential. The electrical energy source in Fig. 1 is a DC electric power source 105, which is symbolized in Fig. 1 by a positive pole ("+") and by a negative pole ("-").

It may be provided for both capacitors 109, 110 a common DC voltage source. Then, the two positive poles of Fig. 1 may be coupled together, and then the two negative poles of Fig. 1 may be coupled together.

Alternatively, a first DC voltage source may be provided for the capacitor 109, and separately, a second DC voltage source may be provided for the capacitor 110. Furthermore, an arrangement of transistor switches 106, 107 is provided, wherein by means of the switching unit formed thereby a time constant electric potential provided by the electric DC voltage source 105 or the time constant electrical voltage, the

Potential difference between positive pole and negative pole corresponds to a time-varying electrical potential is convertible.

For this purpose, the switching unit formed by the first transistor 106 and the second transistor 107, a clock control, which act on the switches 106, 107. As shown in FIG. 1, each of the transistor switches 106, 107 is connected between the two poles of the DC voltage source 105. Now, by means of a suitable clock, a periodic opening and closing of the transistors 106, 107 take place, so that a corresponding pulse signal is applied to a first capacitor 109 or to a second capacitor 110 of the capacitive coupling unit 104.

The two transistor switches 106 may be clocked in phase opposition to each other so that one of the two transistor switches 106 is opened and the other is simultaneously closed simultaneously. The two transistor switches 107 may be clocked in phase opposition to each other so that one of the two transistor switches 107 is opened and the other is simultaneously closed simultaneously. The timing of the two transistor switches 106 and the two transistor switches 107 may be such that the pulse trains generated thereby, which act on the two capacitors 109, 110, are in phase opposition to one another.

Since the capacitances 109, 110 are permeable to an alternating electrical signal, an alternating signal can thereby be transmitted from the first circuit part 101 into the second circuit part 102. The distance of the electrical connections of the two capacitors 109, 1 10 is chosen so large (for example, 1 mm to 10 mm) and their quality or insulation resistance can be selected accordingly, that a flashover of an electrical signal on the capacitive

Coupling unit 104 is avoided. As a result, the power supply circuit 100 is also suitable for energy transmission of a device in a potentially explosive environment.

With a sufficiently large distance of the electrical connections of the capacitors from each other and / or with a sufficient quality of the insulation resistance can also be effected, that a sufficiently good dielectric strength is achieved. Such a good dielectric strength with a simultaneously sufficiently high value of the capacitance can also be achieved by introducing a dielectric (for example with a sufficiently high value of the relative dielectric constant).

Series-connected capacitors can form a non-fault-prone assembly, so that a device can be supplied with energy even in an Ex environment.

The second circuit part 102 includes a rectifier unit 111 which rectifies the time-varying electrical signal applied to the right capacitor plates of the capacitors 109, 110, as shown in FIG. 1, the rectifier unit 111 having a diode circuit (for example a diode bridge circuit).

In Fig. 1, an optional smoothing capacitor 112 for smoothing the circuit characteristic is further shown, wherein between the two terminals of the Rectifier circuit 111, which are not coupled to the capacitors 109, 110, a DC electrical potential is provided, with which the load or device 103 can be supplied with electrical energy.

As shown in FIG. 1, the power supply circuit 100 includes a first branch 113 in the first circuit part 101, in which first branch 113 the first capacitor 109 is disposed. Parallel to the first branch 113, a second branch 114 of the first circuit part 101 is provided, in which the second capacitor 110 is connected. A third branch 115 of the second

Circuit portion 102 again includes the first capacitor 109, and a fourth branch 116 of the second circuit portion 102 includes the second capacitor 110. As shown in FIG. 1, the first and third branches 113, 115 are on the one hand and the second and fourth branches, respectively 114, 116 connected in parallel with each other.

In the following, a field device arrangement 200 according to an exemplary embodiment of the invention will be described with reference to FIG.

The field device arrangement 200 contains a control PC 201, an interface converter 202 and a fill level gauge 203 for measuring the fill level in a connected tank 204 and with a connected power supply unit 207.

The interface converter 202 includes a first port 205, which is a USB port, such that the PC 201 and the interface converter 202 are coupled via the USB bus 205.

Furthermore, the interface converter 202 contains second terminals 206, by means of which the interface converter 202 with the level gauge 203 can be coupled, selectively according to the I2C standard or the HART standard. In the configuration shown in FIG. 2, the interface converter 202 and the level gauge 203 are coupled according to the HART standard. In this coupling according to the HART standard, the port 206 is connected to the level gauge 203 via a connecting line between the level gauge 203 and the level meter 203 energized power supply unit 207.

The interface converter 202 is configured to couple the control PC 201 to the level gauge 203 and has a

Power supply device (as shown in Fig. 1), by means of which the electrical energy requirement of the interface converter 202 can be covered.

Alternatively or additionally, it is possible that with the so of a battery of

PCs 201 in the interface converter 202 coupled energy the level gauge 203 can be operated, for example in a scenario in which a separate power supply 207 of the level gauge 203 is difficult or undesirable.

Furthermore, the interface converter 202 realizes a galvanic isolation between the control PC 201 and the level gauge 203, which is arranged in a potentially explosive environment. This galvanic isolation can be referred to as explosion protection and goes hand in hand with the capacitive energy transfer in the interface converter 202. The energy stored in a con-ceivable capacitor should be sufficiently small to be unsuitable for forming an ignitable spark.

FIG. 3 once again shows a field device arrangement which is coupled to a programming device 300 for setting the data recording can. Furthermore, the patch converter 202 placed here on the level gauge 203 is also shown in FIG.

FIG. 4 shows a further field device arrangement in which a control PC 201 is coupled to the interface converter 202 via a USB bus 205. In this way, a readout of data can be done.

FIG. 5 shows a part of a further field device arrangement in which a programming device 500 is now coupled to the interface converter 202 via a HART connection 206.

6 shows a power supply device according to an exemplary embodiment of the invention.

In the circuit arrangement 600 as a power supply, an integrated circuit 601 is provided which serves to provide a time-varying signal (for example a rectangular pulse) on the basis of a provided DC signal. Such a pulse signal which can be provided at an output of the integrated circuit 601 goes into two parallel branches, in one of which two branches an inverter 602 is connected, which is missing in the other branch.

After passing through inverter 602 in one branch, the signals propagating in the two parallel paths pass through driver stages 603 and 604, respectively. The alternating signals located in these two branches are capable of having first capacitors 605 in the upper one Traversing branch or second capacitors 606 in the lower branch, which not only galvanically isolate the circuit part arranged on the left from the circuit part arranged on the right allow, but simultaneously enable a capacitive energy transfer in the right according to FIG. 6 circuit part.

The alternating signal transmitted in this way in the two branches is rectified by a bridge circuit of diodes 607, so that between two terminals 608 and 609, a DC voltage for supplying power to a load is provided.

The circuit arrangement 700, which is described below with reference to FIG. 7, represents a DC-DC converter according to an exemplary embodiment of the invention.

This allows energy transfer between a PC located on the right side of Fig. 7 and an interface converter shown on the left side.

A power supply 701 serves as a DC voltage source. A clock generator 702 generates a clock with which the DC voltage generated by the power supply unit 701 is converted into a pulse train in accordance with the clock frequency. After the clock has passed through driver or inverter 703, the clock signal acts on first to fourth field-effect transistors 704 to 707. In other words, this clock signal is applied to gate terminals of the field-effect transistors 704 to 707, if necessary after having passed through inversion. Depending on which level these clock signals currently have, the field effect transistors 704 to 707 are conductive or blocking, so that a clocked signal between the source / drain

Terminals of the field effect transistors 704 to 707 is generated. As can be seen from the circuit in FIG. 7, the energy of this energy transmitted through the source / drain terminals and thus via the channel region of the field effect transistors 704 to 707 is taken from the power supply 701. These clocked signals are passed through two parallel connected capacitor chains 708 and 709, which is possible due to the frequency of the pulsed energy signals. In this way, energy is transferred from the PC side (right side of FIG. 7) to the left side of FIG. 7

Led interface converter side and by a rectifier circuit 710, which is composed of four correspondingly connected diodes out.

This rectified power can be used to provide electrical power to a resistor cascade 711, for example, to provide electrical power to the interface converter.

Hereinafter, referring to FIG. 8, a circuit arrangement 800 is described which also serves to transfer power from a USB bus 205 (see FIG. 2) to a HART bus 206 (see FIG. 2).

FIG. 8 shows a plurality of components, reference being made in the following primarily to the energy supply unit 801. An AC voltage source 802 serves as a clock generator. After signals generated therefrom have been passed through corresponding logic elements 803 (or also drivers which serve as energy source), a capacitive coupling circuit 804 is run through, so that after passing through these capacitors 804 at the corresponding terminals, an AC voltage is provided which via the galvanic isolation is provided according to FIG. 8 to the right. After rectification of this AC voltage by a rectifier bridge 805, a DC power supply 806 can be used to supply the HART bus 206 or the elements connected thereto. As an alternative to the HART standard, the data on the right-hand side of FIG. 8 can also be processed according to the I2C standard.

In addition, it should be noted that "exhibit" does not exclude other elements or steps, and "a" or "an" does not exclude a multitude. Further, it should be understood that features or steps described with reference to one of the above embodiments are also used in combination with other features or steps of other embodiments described above. Reference signs are not to be regarded as limitations.

Claims

Patent claims A power supply device for powering a device, the power supply device comprising: a first circuit part; a second circuit part; a capacitive coupling unit; wherein the first circuit part is galvanically isolated from the second circuit part by means of the capacitive coupling unit; wherein the capacitive coupling unit electrical energy from the first circuit part in the second circuit part is capacitively coupled. 2. Energy supply device according to claim 1, wherein the first circuit part comprises an electrical energy source, which is adapted to provide a time-varying electrical potential. 3. Power supply device according to claim 2, wherein the electrical energy source is an electrical AC voltage source. 4. The energy supply device according to claim 2, wherein the electrical energy source has an electrical DC voltage source and a switching unit, wherein by means of the switching unit is provided by the electrical DC voltage source temporally constant electrical potential into the time-varying electrical potential. 5. Power supply device according to claim 4, wherein the switching unit comprises a transistor or a transistor circuit or a driver circuit which is or can be controlled by means of a clock generator. 6. Energy supply device according to one of claims 1 to 5, wherein the capacitive coupling unit comprises at least one element from the group consisting of a capacitor, a capacitor bank, a series circuit of at least two capacitors and a parallel connection of at least two capacitors. 7. Energy supply device according to one of claims 1 to 6, wherein components of the capacitive coupling unit are arranged in such a large distance from each other that a flashover of an electrical signal over these components is prevented away. 8. Energy supply device according to one of claims 1 to 7, wherein components of the capacitive coupling unit have such a small capacitance that an explosion-triggering arcing of an electrical signal is avoided over these components. 9. A power supply device according to any one of claims 1 to 8, wherein the second circuit part comprises an electrical rectifier unit which is adapted to rectify a time-varying electrical signal, which is capacitively coupled via the capacitive coupling unit in the second circuit part. 10. A power supply device according to claim 9, wherein the electrical rectifier unit comprises a diode or a diode circuit. 11. The power supply device according to claim 1, wherein the first circuit part has a first branch and a second branch connected in parallel to the first branch, the second circuit part having a third branch and a fourth branch connected in parallel to the third branch the first branch is capacitively coupled to the third branch and the second branch is capacitively coupled to the fourth branch via the capacitive coupling unit. 12. The power supply device of claim 11, wherein the first branch is capacitively coupled to the third branch via a first capacitor of the capacitive coupling unit, and wherein the second branch is capacitively coupled to the fourth branch via a second capacitor of the capacitive coupling unit. 13. Energy supply device according to one of claims 1 to 12, wherein the device comprises at least one element from the group consisting of an interface device for coupling a control device with a field device, a control device for controlling a field device via an interface device, by means of a control device via an interface device controllable field device, and a programming device for a field device. 14. Energy supply device according to one of claims 1 to 13, wherein by means of the capacitive coupling unit, the electrical energy from the first circuit part in the second circuit part can be coupled purely capacitive. 15. Energy supply device according to one of claims 1 to 14, adapted for supplying the device for operation in a potentially explosive environment with energy. 16. An interface device for coupling a control device to a field device, wherein the interface device comprises a power supply device according to one of claims 1 to 15, wherein the device to be supplied with energy is the interface device and / or the control device and / or the field device. 17. Interface device according to claim 16, comprising a first connection for connecting the control device. The interface device of claim 17, wherein the first port is a USB port. 19. Interface device according to one of claims 16 to 18, wherein the control device is a computer. 20. Interface device according to one of claims 16 to 19, comprising a second terminal for connecting the field device. 21. The interface device of claim 20, wherein the second port is selected from the group consisting of a HART port, an I2C port, a Profϊbus PA, and an FF bus. 22. Interface device according to one of claims 16 to 21, wherein the interface device is set up as an interface converter. 23. Field device arrangement, comprising a field device; An interface device according to any one of claims 16 to 22 for coupling a controller to the field device. 24. Field device arrangement according to claim 23, wherein the field device is a level gauge or a pressure gauge. 25. A method for powering a device, the method comprising: electrically isolating a first circuit part from a second circuit part by means of a capacitive coupling unit; capacitive coupling of electrical energy from the first circuit part into the second circuit part via the capacitive coupling unit.