CIRCUIT ELEMENT, PSE COMPONENT AND METHOD FOR MONITORING AND PROTECTING A PODL NETWORK

Description

[0001] The present invention relates to a circuit element according to the preamble of claim 1, a PSE component according to the preamble of claim 6 and a method for monitoring and protecting a PoOL network according to the preamble of claim 8.

[0002] Safety devices for fieldbus applications are known in the prior art and serve functionally to safely limit power in order to protect people.

[0003] German patent DE 10 2020 113 822 A1 discloses an output safety device in which the output switching elements do not need to be cyclically switched off for testing, as they are located in a permanently active control loop through which their functionality is monitored, including the measurement of gate voltages. This circuit is only designed for bus technologies where the data line is separate from the power supply lines. In Power over Data Line (PoDL) technology, power supply and data are transmitted over the same conductors. Therefore, no additional conductors are available to implement a functionally safe shutdown where the de-energized state is the safe state. The aforementioned solution according to DE 10 2020 113 822 A1 is thus not suitable for transmission technologies such as Power over Data Line (PoOL), Single Pair Ethernet (SPE), etc., where data is transmitted over power supply lines.

[0004] US Patent 7,702,302 B1 discloses a circuit for a single power supply (SPE) that incorporates a field-effect transistor (FET) and a current-measuring resistor in both the forward and return paths of the power supply to enable redundant current measurement. A disadvantage of this circuit is that cyclic testing of the FETs while switched on is not possible, thus preventing a high level of safety. Furthermore, the current-measuring resistors are connected in the power path, resulting in power losses. Finally, US Patent 2019 / 0312751 A1 discloses an SPE circuit that also incorporates a FET in both the forward and return paths of the power supply. A safety algorithm is proposed in which the FETs are switched off sequentially. The disadvantage of this solution is that no communication is possible during the safety algorithm, and therefore the FETs cannot be continuously monitored.

[0005] German patent DE 10 2015 105 702 B3 discloses a bus system with a power supply module and a power consumption module. US patent 2019 / 312751 A1 describes a method for detecting disturbances during power transmission via Power over Ethernet.

[0006] The object of the present invention is to propose an improved interconnection for data-carrying supply lines (PoDL) in which the power is safely limited.

[0007] This problem is solved according to the invention by a circuit element according to the features of claim 1, a PSE component according to the features of claim 6 and a method according to the features of claim 8. Advantageous embodiments are specified in the respective, associated dependent claims.

[0008] The problem is then solved by an electronic interconnection element of a PSE component for a PoDL network or network section, in particular an SPE network or network section, comprising a voltage connection and / or voltage source, a first line for connecting one pole of the voltage connection to a first terminal of a Physical Layer (PHY), a second line for connecting the second pole of the voltage connection to the second terminal of the Physical Layer (PHY), at least one switching element in each of the lines, wherein the switching elements are connected to and controllable by means of at least one control unit comprising a microprocessor, and wherein at least one voltage measuring unit is provided by means of which the voltage drop can be detected as a measured value across each switching element and transmitted to the microprocessor.

[0009] In short, the circuit design involves measuring, calculating, and comparing current and voltage (at least) redundantly to determine the power. Current measurement is achieved (at least in part) by measuring the gate voltages of at least two FETs (field-effect transistors).

[0010] This interconnection element achieves functionally safe power limitation according to IEC 61508. Furthermore, intrinsic safety according to IEEE 802.3cg:2019 can also be achieved. An improved design of the interconnection element involves the two switching elements, in their conducting state, displaying a voltage as a control variable that is proportional to the current flowing through them, and these elements are connected to the control unit via data transmission.

[0011] Advantageously, at least one switching element is a field-effect transistor (FET), in particular a normally closed (nc) field-effect transistor. Alternatively, the switching elements can also be designed as MOSFETs or IGBTs. It is particularly advantageous for comparing voltages and currents if the switching elements are structurally and functionally identical, i.e., identical or substantially identical.

[0012] The invention also includes a (Powering Sourcing Equipment) PSE component for a PoDL network and / or a PoDL network section, in particular a SPE network and / or network section, comprising the following components A microelectronic component with a physical layer (PHY) that can be connected to a powered device (PD) via a line, in particular a SPE connection (TPE); a safety circuit that includes an input voltage source and / or can be connected to one, wherein the safety circuit is located upstream of the microelectronic component, and wherein the safety circuit is configured as a circuit element according to one of the preceding claims. Here, "upstream" means that the safety circuit is provided as a monitoring and protection device between the current input of a voltage source and the microelectronic component comprising a PHY, as well as the powered device (PD).

[0013] The PSE component can be further improved by having the Physical Layer (PHY) have two terminals, with each terminal having a circuit of passive components immediately upstream, in particular at least one resistor and at least one capacitor.

[0014] The interconnection element includes a PHY, a PSE component, and coupling with passive components. The coupling towards the PHY must be designed to be safety-oriented. The failure of a component must not lead to power being coupled in via this path. This can be implemented as proposed in IEEE 802.3cg:2019 for achieving intrinsic safety. There, the critical components are duplicated, connected in series or side-by-side depending on their function.

[0015] Furthermore, the invention includes a method for monitoring and protecting a PoDL network and / or network section, wherein at least one switching element is provided in each of two lines connected to a voltage source and the voltage drop across each switching element is measured, wherein, depending on the actual voltage measurements (controlled variable), the switching elements are controlled by means of a voltage (manipulated variable) which is related to the current flow (disturbance variable).

[0016] In an improved method variant, the current flow in both lines is measured independently and the measured values ​​and / or data derived from them are evaluated together in a processor unit by determining the current flow in each switching element based on the control voltage and comparing the current flow of the two switching elements for monitoring purposes.

[0017] Advantageously, the current flow in each switching element is measured based on the control voltage (U_GS, gate voltage) and the current flow disturbance variable (IS), meaning it is calculated from the control voltages (U_GS, gate voltage). This calculation is performed in parallel and independently in both switching elements. Using the current flows (flow currents) generated and compared in this way, the network or network sections are monitored, and based on this, necessary process control, warning messages, and / or shutdowns are initiated as needed.

[0018] One method improvement consists of tapping the actual voltage measurement value on at least one of the conductor sections of the conductors connected to the voltage source before or after the switching elements, namely The actual voltage is measured between the voltage source and the switching elements (before) and / or after the switching elements, as viewed from the voltage source. In the first case ("before" the switching elements), the actual voltage is measured on the source side of the switching element in the positive terminal line and on the drain side of the switching element in the negative terminal line. In the second case ("after" the switching elements), the actual voltage is measured on the drain side of the switching element in the positive terminal line and on the source side of the switching element in the negative terminal line. The two actual voltages can be measured in parallel, sequentially, and / or at a pulsed rate for monitoring purposes.

[0019] The method involves placing the switching elements, such as the FET, in a control loop. The current flow is determined in parallel based on the gate voltage (U_GS), and the current flow of the two switching elements is compared and monitored. If an imbalance in the current flow is detected, both switching elements are switched off, as this imbalance indicates a fault, either within the switching element itself or due to an external potential coupling.

[0020] Here, the redundantly measured current flow is evaluated and compared with a target value, such as a FET characteristic curve. The current is not actively limited under normal circumstances, but rather monitored and switched off if a limit is exceeded. The PHY transmit power is not measured, monitored, or limited separately; instead, the actual power supply and / or the voltage source itself is completely switched off. Advantageously, a transmit power of the PHY remains as an autonomous signal even after a shutdown, provided its transmit power is less than 0.5 watts.

[0021] To monitor the functionality and performance of the switching elements themselves, a further improved method variant provides for the storage of a target characteristic curve for each switching element. The resistance value and / or the gate voltage (U_GS) of the two switching elements are then varied within defined limits, and the actual value is compared with the target characteristic curve and / or the corridor of the target characteristic curve for the respective switching element. The change in the resistance value and / or the respective gate voltage (U_GS) can be performed individually or synchronously.

[0022] Another improved procedure variant provides that after a shutdown due to the detection of unequal current strength and / or unequal current flow, user intervention takes place before a restart, in particular after a fault analysis and / or fault correction by a user or a specification from the control system by specifying an output limit or a power limit, a restart and / or normal operation takes place based on internal specifications of the control system.

[0023] Advantageously, the method employs a PSE component designed and operated according to one of the aforementioned embodiments. The method described herein, in its various embodiments, can be used in particular for a power and data network in which data transmission and power supply are carried out together via a two-wire cable, especially a Single Pair Ethernet (SPE) and / or Twisted Pair Ethernet (TPE).

[0024] The current can be limited by a complete current shutdown to 0 A or to a defined value > 0, in particular to a value up to 100 mA. The advantage of a partial shutdown is that data transmission can continue with the low current flow, for example to transmit status data or forward control commands.

[0025] The particular advantage lies in the fact that the same FETs used as output switching elements for current measurement are also used for shutdown, thus eliminating the need for additional components in the power path. This circuit also enables safe power limiting and shutdown of an electronic component or device that does not itself include a safety function, such as a frequency converter. The circuit according to the invention eliminates the need for complex, functionally safe bus communication, as the power limiting and, if necessary, shutdown occur at a higher level.

[0026] Further details and advantages of the invention will now be explained in more detail with reference to exemplary embodiments illustrated in drawings.

[0027] It shows: Fig. 1 a circuit diagram of a first embodiment, Fig. 2 a circuit diagram of a further embodiment and Fig. 3 a sketch of the circuit as well as graphs of the characteristic curves of the FET.

[0028] The in Figure 1 The PoDL network or network segment 1 shown is structured as regularly specified in IEEE 802.3cg:2019. It includes a Physical Layer 8 (PHY) for data communication on both sides of the SPE link 4, namely on the side of PSE 3 (Power Sourcing Equipment) and on the other side of the SPE link, PD 2 (Powered Device).

[0029] The embodiment according to the invention relates to the side of the PSE 3, so that the PD 2 is not described in detail and comprises the (micro-)electronic components and parts known to the person skilled in the art.

[0030] The PSE 3 essentially comprises a protective circuit 9 consisting of the PHY 8 and the passive components 7.1 and 7.2, and a connecting element 5. The protective circuit 9 includes the passive components 7.1 and 7.2 for coupling the PHY and PSE. Such passive components 7.1 and 7.2 are necessary for this coupling. The passive component 7.1 must be designed to be safety-oriented. This ensures that the protective function is maintained in the event of a single fault, making a safety-relevant fault highly unlikely. The transmit power of the PHY 8 is considered the minimum power level. Ideally, the detection of the PD 2 via a detection voltage and the transmission of the power classes via SCCP (Serial Communication Classification Protocol) comply with the usual standards. In this case, the protective circuit 9 includes a passive component 7.1 comprising a resistor 16 and a capacitor 17 connected in series.The structure of the second, passive component 7.2 is enlarged in the detailed view below and shown with the individual components.

[0031] The interconnection element 5 comprises a voltage terminal 30 (positive position) with a first line 31, which leads to the first terminal 8.1 of a physical layer (PHY) 8. The second line 32 connects the other voltage terminal 30 (negative terminal) to the second terminal 8.2 of the PHY 8 of the PSE 3. Both lines 31, 32 each comprise a switching element 10, 20 designed as a FET. The voltage terminal 30 can lead to an external source, as shown in Figure 1 indicated or formed in an integrated source, such as a battery, as in Figure 2The diagram illustrates a central control unit 15. This unit uses the wire pair 11, 13 in the first line 31 and the wire pair 21, 23 in the second line 32 to measure the voltage (U_DS) across the respective switching element 10, 20 (FET). Each switching element 10, 20 is further controlled and regulated via its associated control line 12, 22, which is connected to the control unit 15. The control unit 15, which, for example, has a circuit board as its base, also includes a microprocessor 6 for at least part of the data processing and a voltage meter 18. Other, conventional (micro)electronic elements of the control unit 15 are not shown. In the illustrated embodiment, the control is performed electronically via operational amplifiers, but can also be performed via the microprocessor. In this case, the microprocessor serves control and monitoring purposes.

[0032] The functionally safe shutdown according to the invention only affects the PSE 3. Therefore, during shutdown, the power can only be limited to the maximum transmit power of the PHY 8. Ethernet can optionally be used as a black channel for a safe protocol. Thus, it is possible to operate a safe protocol (e.g., PROFIsafe or CIPP Safety). Both a safe protocol and a standard protocol can be used. However, the advantage of the invention is that the overarching safe shutdown is also possible without a safe protocol.

[0033] The rated voltages and currents for the PSE 3 according to IEEE 802.3cg:2019 are listed in the table below and can all be provided. Table Class 0 1 2 3 4 5 6 7 8 9 Voltage [V] 5.5-18 5.5-18 14-18 14-18 12-36 12-36 26-36 26-36 48-60 48-60 Current [A] 0.1 0 0.22 0.25 0.47 0.10 0.34 0.21 0.46 0.73 1.3 PD power 0.5 1 3 5 1 3 5 10 30 50

[0034] In the Figure 1An additional ammeter 14 is shown as an optional extension, which is also connected to the control unit 15 via a data line marked with a dash. The current flow measured in the positive terminal line 31 can be compared with the currents determined from the voltages and used for monitoring. As in Figure 2 As shown, this additional, separate current measurement can be further improved if an additional ammeter 14.1, 14.2 is provided in both lines 31, 32 and the currents thus determined are compared and used for monitoring.

[0035] As in the Figure 3 In the implemented state, the switching elements (FETs) are in a control loop 24 in which the voltage 34 (U_DS) is kept constant as the controlled variable. This voltage 34 is tapped from line 31 via lines 11 and 13, and from line 32 via lines 21 and 23, as shown in the Figure 1 and2 The gate voltage 35 (U_GS) applied via the control lines 12, 22 is in a typical ratio to the disturbance variable 33 (I_S) of the flowing current. This relationship can be derived for each actuator 10, 12 from a component-specific characteristic curve, as shown in the lower graph in the Figure 3 was depicted.

[0036] Furthermore, as indicated by the dashed arrow, the output voltage 19 (U_IST) can optionally be measured (redundantly) via lines 13 in the first line 31 (positive terminal) and the second line 32 (negative terminal) via line 23, which was previously referred to as "after" the switching elements 10, 20. Alternatively, a measurement can be taken analogously via the line pair 11, 21, which was previously referred to as "before" the switching elements 10, 20.

[0037] If only the power supply is switched off, PHY 8 is limited to its transmit power. In this case, it is not necessary to measure the power or current precisely. The current measurement primarily serves to monitor the switching elements 10 and 20, which are designed as FETs. Therefore, in this variant, only two safe power levels are typically provided.

[0038] Alternatively, a safety-oriented measurement of the current and voltage can be performed, from which the power is calculated. This is compared to a specification, such as the power classes according to IEEE 802.3cg:2019 as shown in the table above. For this to work, the specification must be configured safely. Any Skinny Client Control Protocol (SCCP) in place provides a monitoring function. If the specification is not met, a safe shutdown is initiated. Reference symbol list

[0039] 1 PoDL network or network section (1) 2 Powered Device (PD) 3 PSE component 4 SPE 5 Interconnect element (5) 6 Microprocessor, processor unit 7 Passive component (also 7.1, 7.2) 8 Physical Layer (PHY) 8.1 First connection 8.2 Second connection 9 Protection circuit 10 Switching element 11 Line 12 Control line 13 Line 14 Ammeter (also 14.1, 14.2) 15 Control unit 16 Resistor 17 Capacitor 18 Voltmeter 19 Output voltage (U_IST) 20 Switching element 21 Line 22 Control line 23 Line 24 Control loop 27 Controlled system 28 Reference input (U_Ref) 29 Feedback 30 Voltage connection 31 First line 32 Second line 33 Disturbance variable (I_S) 34 Controlled variable (U_DS) 35 Manipulated variable (U_GS)

Claims

1. Electronic interconnection element (5) for a PSE component, (3), "Power Sourcing Equipment" component, for a PoDL network or network section (1), "Power over Data Line", comprising - a voltage terminal (30) and / or voltage source, - a first line (31) for connecting a pole of the voltage terminal (30) to a first terminal (8.1) of a PHY (8), - a second line (32) for connecting the second pole of the voltage terminal (30) to a second terminal (8.2) of the PHY (8), - at least one switching element (10, 20) in each of the lines (31, 32), characterized in that the switching elements (10, 20) are connected to at least one control unit (15) comprising a microprocessor (6) and can thus be controlled by means of a voltage that is related to the current flow, and wherein at least one voltage measuring unit (18) is provided, by means of which a voltage drop, as measured value, across each switching element (10, 20) can be detected and supplied to the microprocessor (6) as ACTUAL voltage measured values, wherein the control unit (15) is set up to actuate the switching elements (10, 20) depending on the ACTUAL voltage measured values, so that the voltage drop (U_DS) across each switching element (10, 20) is kept constant as a control variable.

2. Interconnection element (5) according to Claim 1, characterized in that an ammeter (14.1, 14.2), which is connected to the control unit (15) for data transmission, is provided to measure a current flow in at least one line (31, 32).

3. Interconnection element (5) according to either one of Claims 1 and 2, characterized in that at least one switching element (10, 20) is a field-effect transistor, FET, in particular a normally closed, nc, field-effect transistor.

4. Interconnection element (5) according to Claim 3, characterized in that the at least one switching element (10, 20) is a MOSFET or an IGBT.

5. Interconnection element (5) according to any one of the preceding claims, characterized in that the switching elements (10, 20) are identical in terms of construction and function.

6. PSE component (3) for a PoDL network and / or a PoDL network section (1), comprising - a microelectronic component (9) having a PHY (8), which can be connected via a line to a Powered Device, PD, (2), - a safety circuit which comprises a voltage source and / or which can be connected thereto, wherein the safety circuit is located upstream of the microelectronic component (9), characterized in that the safety circuit is in the form of an interconnection element (5) according to any one of the preceding claims.

7. PSE component (3) according to Claim 6, characterized in that the PHY (8) has two terminals (8.1, 8.2), wherein an interconnection of passive components is located directly upstream of each of the terminals (8.1, 8.2), in particular an interconnection of at least one resistor (16) and at least one capacitance (17).

8. Method for monitoring and protecting a PoDL network and / or network section, wherein at least one switching element (10, 20) is provided in each of two lines (31, 32) that are connected to a voltage source, and the voltage drop (U_DS) across each switching element (10, 20) is measured as ACTUAL voltage measured values, characterized in that, depending on the ACTUAL voltage measured values, the switching elements (10, 20) are actuated by means of an actuation voltage that is related to the current flow, wherein the switching elements (10, 20) are actuated depending on the ACTUAL voltage measured values in such a way that the voltage drop (U_DS) across each switching element (10, 20) is kept constant as a control variable.

9. Method according to Claim 8, characterized in that the current flow is measured in both lines (31, 32) technically independently and the measured values and / or data derived therefrom are evaluated together in a processor unit (6).

10. Method according to Claim 9, characterized in that the current flow in each switching element (10, 20) is determined on the basis of the actuation voltages of the current flow (33) of the two switching elements (10, 20) and compared for monitoring.

11. Method according to any one of Claims 8 to 10, characterized in that the ACTUAL voltage measured value on the line sections of the lines (31, 32) is detected a) between the voltage source and the switching element (10, 20) and / or b) downstream of the switching elements (10, 20) as seen from the voltage source.

12. Method according to any one of Claims 8 to 11, characterized in that, after a shutdown due to a) detection of an unequal current, a user intervention takes place before a restart, in particular after a fault analysis and / or troubleshooting by a user, or b) a control specification by specifying an output limit or a power limit, a restart and / or normal operation is carried out on the basis of internal control specifications.

13. Method according to any one of Claims 8 to 12, characterized in that a PSE component (3) according to either one of Claims 6 and 7 is used and operated.

14. Method according to any one of Claims 8 to 13, characterized in that the method is used for a supply and data network, in which the data is transmitted and the current is carried together via a two-wire cable, in particular a Single Pair Ethernet, SPE, (4) and / or Twisted Pair Ethernet, TPE.

15. Method according to any one of Claims 8 to 14, characterized in that limiting the current includes cutting off the current - to 0 A or - to a defined value > 0, in particular a value up to 100 mA.

16. Method according to any one of Claims 8 to 15, characterized in that the current intensity (33) of the two switching elements is calculated from the ACTUAL voltage measured values (U_GS) at the two switching elements (10, 20) and that this current intensity (33) is compared with a SETPOINT current intensity specified in the processor unit (6) and additionally with an independently measured ACTUAL current intensity in at least one of two cable paths (30, 31), wherein a shutdown takes place depending on this comparison.