Field device for providing energy from network to sensor unit

Abstract

The present disclosure relates to the field of field devices. The field device includes: a first input terminal configured to be connected to a first wire of a network; a second input terminal configured to be connected to a second wire of the network; a first output terminal configured to be connected to a first wire of the sensor unit; a second output terminal configured to be connected to a second wire of the sensor unit; a rectifier unit, a first portion of which is arranged between the first input terminal and the first node, and a second portion of which is arranged between the second input terminal and the second node; a current measuring device arranged between the second node and the third node; a voltage measurement means for measuring a measurement voltage between the first node and the second node; a first semiconductor disposed between the first node and the third node, and configured to pass a bypass current through the first semiconductor such that the measured current includes a two-part curve; and a second semiconductor disposed between the third node and the second output terminal.

Description

Technical Field

[0001] This disclosure relates to the field of field devices, and more particularly to field devices that provide power from a network to sensor units. This disclosure also relates to field device systems and applications. Background Technology

[0002] Various types of networks can be defined to provide power to devices connected to one of these networks. Examples may include networks that provide Ethernet connectivity and are suitable for two-wire Ethernet topologies, such as Ethernet APL (Advanced Physical Layer) or Ethernet SPE (Single-Pair Ethernet) networks. However, these networks have some different specifications, such as different power supply voltages, and other limitations, such as the minimum current required to flow through each field device connected to one of these networks. Therefore, it is desirable to have a field device that can handle at least these two network types and meet these two specifications. Summary of the Invention

[0003] The object of this disclosure is to provide a field device capable of connecting to both Ethernet APL (Advanced Physical Layer) and Ethernet SPE (Single-Pair Ethernet) networks. This object is achieved through the subject matter of the independent claims. Other embodiments will become apparent from the dependent claims and the following description.

[0004] One aspect relates to a field device designed to supply power from a two-wire network to a sensor unit. The field device includes:

[0005] The first input terminal is configured to be connected to the first wire of the network;

[0006] The second input terminal is configured to be connected to a second wire of the network;

[0007] The first output terminal is configured to be connected to the first wire of the sensor unit;

[0008] The second output terminal is configured to be connected to the second wire of the sensor unit;

[0009] A rectifier unit, wherein a first part of the rectifier unit is arranged between a first input terminal and a first node and a second part of the rectifier unit is arranged between a second input terminal and a second node, wherein the first node is connected to a first output terminal;

[0010] A current measuring device is installed between the second node and the third node to measure the current between the second node and the third node;

[0011] A voltage measuring device for measuring the voltage between a first node and a second node;

[0012] A first semiconductor is disposed between the first node and the third node and is configured to allow bypass current to pass through the first semiconductor.

[0013] This results in the measured current, which is the sum of the bypass current and the load current through the sensor unit, comprising a two-part curve: a negative linear current-voltage correlation in the low-voltage portion and a constant current in the high-voltage portion; and

[0014] The second semiconductor is disposed between the third node and the second output terminal.

[0015] Field devices can be designed as a "field device core" or "electrical middleware" between an Ethernet-based network and sensor units. The Ethernet-based network can be, for example, an Ethernet APL (Advanced Physical Layer) or an Ethernet SPE (Single-Pair Ethernet) network. The power supply voltage for Ethernet APL is defined between 9.6V and 15V, and the power supply voltage for Ethernet SPE (port classes 10, 11, and 12) is defined between 20V and 30V. Other types of Ethernet SPEs can have higher voltages. Each field device connected to these types of Ethernet-based networks needs to meet at least a specific set of limitations to ensure proper network system operation. These limitations may include that the current change caused by a field device connected to the network should not have a rate of change higher than 10mA / ms. Further limitations may also be applied. Since not all sensor units can guarantee this, measures need to be taken to comply with these limitations.

[0016] The first and second input terminals can be connected to the network, for example, via clamps and / or other types of connectors.

[0017] The sensor unit or "load" can be configured to perform measurements, including in at least some cases measurements of, for example, temperature, pressure, flow rate, and / or distance. The sensor unit may include, for example, a sensor front-end for the application, and / or a display for showing any kind of values ​​and / or graphs, especially measured values. The sensor unit may include, for example, a processor with memory, which can be used as a control unit, a data processing unit, and / or for other purposes, such as programming an EEPROM. Therefore, on the one hand, the sensor unit may have fluctuating current, and the Ethernet-based network defines the minimum and maximum current that can (and / or needs) be transmitted to each sensor unit connected to the network.

[0018] The rectifier unit may include a bridge rectifier or series diodes. The rectifier may include measures to provide a constant current.

[0019] The current measuring device can be implemented as a series or "parallel" resistor, a Hall sensor, and / or another type of device. The current measuring device measures the current passing through the sensor unit and through the control components (e.g., first and second semiconductors) of the field device.

[0020] The voltage measuring device can be a high-impedance device. The voltage measuring device is configured to measure the voltage between the first node and the second node.

[0021] A first semiconductor device is disposed between the first and third nodes and is substantially in parallel with the load or sensor unit. The first semiconductor is configured to allow a bypass current to pass through it; the current can be controlled by a first control unit. The control can be designed such that the measuring current is controlled by controlling the bypass current, the measuring current being the sum of the bypass current and the load current passing through the sensor unit. The measuring current can be referred to as the target value of the controlled field device. The measuring current can be depicted by a two-part curve, for example... Figure 2 The curve shown has the following characteristics. The first part of the curve, or the low-voltage portion, exhibits a negative linear current-voltage correlation; that is, this part is a linearly decreasing function, where the current decreases as the voltage from the network increases. In other words, the current decreases linearly as the voltage increases until it reaches its lower limit. The second part of the curve, or the high-voltage portion, exhibits a constant current, meaning the current measured in this part remains the same. Furthermore, a lowest voltage portion can be implemented, exhibiting a constant current for voltages below the low-voltage portion. This can be achieved within the first control unit and can be accomplished through a resistor network including active components such as operational amplifiers.

[0022] The second semiconductor is positioned between the third node and the second output terminal. It can be advantageously used to limit the current passing through the sensor unit.

[0023] The field device supports a wide voltage range. Therefore, it can advantageously connect to a wide range of Ethernet-based network types and / or subtypes. In particular, the field device can advantageously connect to both Ethernet APL (Advanced Physical Layer) and Ethernet SPE (Single-Pair Ethernet) networks. Furthermore, the field device meets the limitation of a current change rate not exceeding 10 mA / ms, caused by the field device plus a sensor unit, which can be connected to the network as a system. The linear current-voltage correlation allows implementation in circuits with linear components, thus simplifying the implementation. Fast control can be achieved, yet with low risk of oscillating control loops. Moreover, the field device can achieve relatively constant power consumption, for example, within the APL voltage range. This can be particularly advantageous for field devices that need to meet "Ex" (explosive atmosphere) specifications, for example, by keeping the overall heating of the device small, especially due to its low power consumption, which may help meet Ex temperature ratings.

[0024] In various embodiments, the second semiconductor device is configured to initially close and slowly open during the startup phase. "Initially" may mean immediately after the field device is turned on, or, for example, immediately after a hardware reset. The slow opening (i.e., on the order of milliseconds) can be achieved by an RC component that may be connected to an amplifier.

[0025] In various embodiments, the second semiconductor is further configured to limit the measurement current. This is particularly advantageous in the event of a sensor unit failure.

[0026] In various embodiments, the network is an Ethernet-based network, particularly a two-wire Ethernet-based network, such as an Ethernet APL network or an Ethernet SPE network. These networks define subtypes. Field devices can be configured to connect to one or more subtypes of these networks.

[0027] These networks are capable of supplying power to field devices solely from the Ethernet-based network. Therefore, additional power supply units may become obsolete. Specifications for such networks can be found in, for example, the IEEE standard for Ethernet Correction 5: “Physical layer specifications and management parameters for 10 Mb / s operation and associated power delivery over a single balanced conductor pair.” For instance, for port classes 10, 11, and 12, Ethernet-based APL (Advanced Physical Layer) is defined for voltage ranges between 9.6V and 15V, and Ethernet-based SPE (Single Pair Ethernet) is defined for voltage ranges between 20V and 30V. This allows for the use of a single design for multiple two-wire network standards.

[0028] In various embodiments, the bend voltage of the kink in the control curve is defined as the voltage between the voltage range of the Ethernet APL network and the voltage range of the Ethernet SPE network, wherein the control curve implements the dependence of the maximum setpoint current on the network voltage. Figure 2 The diagram illustrates such control curves. Ethernet APL networks, Type A or Type C, are defined as voltage ranges between 9.6V and 15V, or between 11.61V and 15V, respectively. Ethernet SPE networks are defined for voltage ranges between 20V and 30V. Therefore, when the field device supports both of these networks, the bend voltage can be any voltage between 15V and 20V (or in some cases higher), such as 17V, 18V, etc. Below the bend voltage, a negative linear correlation between the maximum setpoint current and the network voltage can be achieved, while above the bend voltage, a constant correlation between the setpoint current and the network voltage can be achieved.

[0029] In various embodiments, the network has a voltage range between 5V and 50V, particularly between 9V and 30V. Essentially, the field devices described above and / or below can be used in a very wide range of field devices. The wide range can be limited, for example, by the voltage range of the semiconductors used in the field device and / or by cost or cost-effectiveness considerations. A control curve having a bend between two voltage sub-ranges (e.g., a low voltage range and a high voltage range) can advantageously allow field devices to be used over a wide voltage range of the network.

[0030] In various embodiments, the first semiconductor device is further configured to ensure that the measured current does not fall below a lower current limit. The lower current limit can be defined by the network, for example, as the minimum current required to flow through each field device connected to the network. Some networks may define, for example, a minimum current of 10mA to make it easier to distinguish between connected and unconnected devices, and / or for greater stability and / or less current fluctuation within the network.

[0031] In various embodiments, the first semiconductor device is also configured to ensure that the bypass current does not exceed the maximum current, which is limited by the maximum permissible power dissipation of the first semiconductor device. This can advantageously prevent the first semiconductor device from being thermally damaged and / or prematurely degraded.

[0032] In various embodiments, the first semiconductor device and / or the second semiconductor device is a bipolar semiconductor device, a MOSFET semiconductor device, a PMOS semiconductor device, and / or an NMOS semiconductor device. NMOS semiconductor devices may be preferred due to their electrical characteristics and / or because they typically represent a wider range of NMOS semiconductor device types than PMOS semiconductor devices.

[0033] One aspect relates to a field device system comprising a field device as described above and / or below, and a sensor unit as described above and / or below. The sensor unit may be adapted to the field device, for example, a field device specified for a predetermined voltage range and / or current range.

[0034] One aspect relates to the use of field devices as described above and / or below for supplying power to sensor units from a network, particularly from an Ethernet-based network.

[0035] For further illustration, this disclosure is described with reference to embodiments shown in the accompanying drawings. These embodiments are considered examples only and not limitations. Attached Figure Description

[0036] Figure 1 A field device according to an embodiment is schematically illustrated;

[0037] Figure 2This is based on the correlation between the maximum setup current and the network voltage according to one embodiment;

[0038] Figure 3 This is the correlation between the maximum power of the field device and the voltage of the network according to the embodiment;

[0039] Figure 4 It is a control unit according to one embodiment. Detailed Implementation

[0040] Figure 1 A field device 100 is schematically shown, arranged between a network 200 and a sensor unit 300. The field device 100 supplies power from the network 200 to the sensor unit 300. This power from the network 200 may be the sole power source for the sensor unit 300. The sensor unit 300 is powered via output terminals 180 and 190. The sensor unit 300 may be a standalone device or may be integrated into the field device 100. The sensor unit 300 may be detachably coupled to the field device 100. The network 200 may be an Ethernet-based network, such as Ethernet APL, Ethernet SPE, or other types of two-wire networks. The field device 100 is connected to the network 200 via terminals 210 and 220. Terminals 210 and 220 may be implemented as, for example, screw or clamp terminals or via M8 or M12 connectors.

[0041] Terminals 210 and 220 are connected to rectifier unit 105, which is arranged between network 200 (or: terminals 210 and 220) and first node 110. A current measuring device 115 is provided between second node 120 and third node 130. The current measuring device 115 measures the current I between second node 120 and third node 130. M The measured current I M Essentially, it can be the total current through the sensor unit 300 plus the current through the control device, i.e., through the first semiconductor device 140 and the second semiconductor device 150 plus the current from some secondary consumable devices. The field device also includes a measuring voltage V for measuring the voltage between the first node 110 and the second node 120. M Voltage measuring device 125.

[0042] A first semiconductor device 140 is disposed between the first node 110 and the third node 130, and is therefore substantially parallel to the sensor unit 300. A second semiconductor device 150 is disposed between the third node 130 and the second output terminal 190, and is controlled by the second control unit 152. The first semiconductor device 140 is configured to cause a bypass current I... B The current flows through the first semiconductor device 140, thereby controlling the measurement current I. MMeasuring current I M It is the bypass current I B With the load current I flowing through sensor unit 300 L The sum. The first semiconductor device 140 is controlled by the first control unit 142, which uses a measured voltage V. M and measuring current I M As input, the first control unit 142 controls the bypass current I through the first semiconductor device 140 in a manner that achieves current-voltage correlation. B ,like Figure 2 As shown in the example.

[0043] The Figure 2 The maximum setpoint current I according to the embodiment is shown. 设置点 With network voltage U 网络 The example illustrates the dependencies. In the example shown, a control function for a field device is described that supports both Ethernet APL networks (Type A) with voltage ranges between 9.6V and 15V and Ethernet SPEs with voltage ranges between 20V and 30V. The control function comprises two-part curves. These two-part curves are... Figure 2 The circuit has a low-voltage section between terminals 210 and 220, between a bending voltage VT of 9.6V and (exemplarily) 17V. In the low-voltage section, a negative linear current-voltage dependence can be observed, with a maximum current of 43mA at 9.6V and a minimum current of 22mA at 17V, and the current decreases linearly between these points. In the high-voltage section following the low-voltage section, a constant current of 22mA can be observed extending from the (exemplarily) 17V bending voltage VT to a maximum support voltage of 30V. The current at input terminals 210 and 220 can be adjusted according to the power P at terminals 210 and 200. 输入 To select, the sensor unit 300 can be supported at terminals 180 and 190 via field device 100.

[0044] For example, for P 输入 =375mW, input voltage U at terminals 210 and 220 网络 For a voltage of 9V, the required input current I in for:

[0045] I in =375mW / 9V≈42mA

[0046] Under this assumption, the bending voltage V is selected. T The method is to, for the selected current I L In V T To obtain similar power P 输入 For example, for I L=22mA current, bending voltage V T for:

[0047] V T =375mW / 22mA≈17V

[0048] It should be noted that this example is only a rough calculation example of the value of interest. Specifically, the power of the control components of the field device 100 (e.g., the first control unit 142 and the second control unit 152) is ignored. For detailed calculations, additional factors, such as selection tolerances, temperature drift, and / or other aspects, can be considered. For any possible reason, different input power can also be selected at the two ends of the low voltage section, for example, 400mW (e.g., 9.6V) at the lower end and 450mW (e.g., 22.5V) at the upper end. Applying this example, the current at the lower end will be approximately 400mW / 9.6V ≈ 42mA, and the voltage at the upper end, and for 22mA, will be approximately 450mW / 22mA ≈ 20.5V.

[0049] choose Figure 2 The chart as a result of the control curve is as follows Figure 3 As shown. Figure 3 according to Figure 2 The control curves show the maximum power of the field device 100 and the network voltage U according to the embodiment. 网络 An exemplary correlation. The power consumed in field device 100 is essentially V. M and I M The product of (ignoring some minor consumers). For example... Figure 3 As shown, Figure 2 The current control curve results in fairly stable power dissipation throughout the low-voltage section. This can also be considered when selecting the bending voltage VT. Figure 3 The curve: The voltage VT can be selected in such a way that the power consumed at VT is approximately the same as the power consumed at the lowest voltage of the low voltage section.

[0050] When watching Figure 3 At that time, it can be clearly seen Figure 2 The relatively easy-to-implement control curve results in fairly stable power consumption throughout the low-voltage range. Furthermore, control can be very fast, ensuring that current changes caused by field devices do not have a rate of change higher than 10 mA / ms (as specified for some Ethernet-based networks), typically significantly lower than 10 mA / ms. On the other hand, the linear control curve is found to be a significant measure to reduce the risk of oscillating control. Moreover, the field device can be used over a wide voltage range. Therefore, it can advantageously connect to a wide range of Ethernet-based network types and / or subtypes, as exemplarily shown for Ethernet APL and Ethernet SPE networks.

[0051] Figure 4 An exemplary implementation of a control unit 142 according to an embodiment is shown. The first control unit 142 includes a Y-shaped resistor network, wherein the intermediate node M is directed to a controller 148 that controls a first semiconductor device 140 (see...). Figure 1 The second input of controller 148 is connected to current measuring device 115. Current measuring device 115 measures the measured current I. M ,

[0052] Current I M It is through the bypass current I of the first semiconductor device 140 B and via sensor unit 300 (see Figure 1 The load current I L The sum of the values. The left branch of the Y-shaped resistor network includes resistors R1 and R2 connected in series, which form a voltage divider to establish a constant voltage from voltage reference 144. R1 can be significantly higher than R2. Setting point V 设置1 A value is set that determines the constant current in the high-voltage section. The left branch of the Y-shaped resistor network includes resistor R3 (and a common resistor R2), with R3 connected in series with the setpoint adjustment unit 146. For the low-voltage section, the setpoint adjustment unit 146 adjusts the setpoint voltage V via R3. 设置2 This ensures that, for the voltage portion, the first semiconductor device 140 is controlled only by the left branch of the Y-shaped resistor network. The setpoint adjustment unit 146 has an input V... 设置2 The input V 设置2 By setting a bending voltage VT and reducing it through the resistance of the setting point adjustment unit 146, a linear curve for the low-voltage portion can be achieved. Another input to the setting point adjustment unit 146 is the voltage V. 设置2 With the measured (actual) voltage V M Compare them.

[0053] Figure Labels

[0054] 100 field devices

[0055] 105 rectifier unit

[0056] 110 First Node

[0057] 115 Current Measuring Device

[0058] 120 Second Node

[0059] 125 Voltage Measuring Device

[0060] 140 First Semiconductor Device

[0061] 142 First Control Unit

[0062] 144 voltage reference

[0063] 146 setpoint adjustment unit

[0064] 148 controller

[0065] 150 Second Semiconductor Device

[0066] 152 Second Control Unit

[0067] 160 reference nodes

[0068] 170 controller

[0069] 180 First Output Terminal

[0070] 190 Second Output Terminal

[0071] 200 Network

[0072] 210 First Input Terminal

[0073] 220 Second Input Terminal

[0074] 300 sensor units, load

Claims

1. A field device (100) designed to supply energy from a two-wire network (200) to a sensor unit (300), the field device (100) comprising: The first input terminal (210) is configured to be connected to the first wire of the network (200); The second input terminal (220) is configured to be connected to the second wire of the network (200); The first output terminal (180) is configured to be connected to the first wire of the sensor unit (300); The second output terminal (190) is configured to be connected to the second wire of the sensor unit (300); A rectifier unit (105) has a first portion disposed between the first input terminal (210) and a first node (110), and a second portion disposed between the second input terminal (220) and a second node (120), wherein the first node (110) is connected to the first output terminal (180). A current measuring device (115) is arranged between the second node (120) and the third node (130) for measuring the measuring current (I) between the second node (120) and the third node (130). M ); A voltage measuring device (125) is used to measure the voltage (V) between the first node (110) and the second node (120). M ); A first semiconductor device (140) is disposed between the first node (110) and the third node (130) and is configured to allow a bypass current (I0) to pass through. B () through the first semiconductor device (140), So that the bypass current (I) B ) and the load current (I) through the sensor unit (300) L The sum of the measured currents (I) M The curve consists of two parts, which have a negative linear current-voltage correlation in the low-voltage part and a constant current in the high-voltage part. as well as A second semiconductor device (150) is disposed between the third node (130) and the second output terminal (190).

2. The field device (100) according to claim 1, The second semiconductor device (150) is configured to be initially closed and slowly disconnected during the startup phase.

3. The field device (100) according to claim 1 or 2, The second semiconductor device (150) is configured to limit the measurement current (I0). M This is especially true in the event of a failure in the sensor unit (300).

4. The field device (100) according to any one of the preceding claims, The network (200) mentioned therein is an Ethernet-based network, especially an Ethernet APL network or an Ethernet SPE network.

5. The field device (100) according to any one of the preceding claims, The bend voltage (VT) in the control curve is defined as the voltage between the voltage range of the Ethernet APL network and the voltage range of the Ethernet SPE network. The control curve achieves the maximum setpoint current (I) 设置点 ) for network voltage (U 网络 ) dependency.

6. The field device (100) according to any one of the preceding claims, The network voltage (U) of the network (200) 网络 It has a voltage range between 5V and 50V, especially between 9V and 30V.

7. The field device (100) according to any one of the preceding claims, The first semiconductor device (140) is further configured to realize the measured current (I M (Not lower than the lower limit of current) 8. The field device (100) according to any one of the preceding claims, The first semiconductor device (140) is further configured to realize the bypass current (I B The power consumption is not higher than the maximum allowable power consumption of the first semiconductor device (140).

9. The field device (100) according to any one of the preceding claims, The first semiconductor device (140) and / or the second semiconductor device (150) are bipolar semiconductor devices, MOSFET semiconductor devices, PMOS semiconductor devices and / or NMOS semiconductor devices.

10. A field device system comprising a field device (100) according to any one of the preceding claims and a sensor unit (300).

11. Use of the field device (100) according to any one of claims 1-9 for supplying energy from a network (200) to a sensor unit (300), particularly for supplying energy from an Ethernet-based network to the sensor unit (300).

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