WO2019057843A1 - Method and system for wire interruption detection for guarded sensors - Google Patents

Method and system for wire interruption detection for guarded sensors Download PDF

Info

Publication number
WO2019057843A1
WO2019057843A1 PCT/EP2018/075520 EP2018075520W WO2019057843A1 WO 2019057843 A1 WO2019057843 A1 WO 2019057843A1 EP 2018075520 W EP2018075520 W EP 2018075520W WO 2019057843 A1 WO2019057843 A1 WO 2019057843A1
Authority
WO
WIPO (PCT)
Prior art keywords
guard
sense
wire
detection unit
node
Prior art date
Application number
PCT/EP2018/075520
Other languages
French (fr)
Inventor
Thomas John
Original Assignee
Iee International Electronics & Engineering S.A.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Iee International Electronics & Engineering S.A. filed Critical Iee International Electronics & Engineering S.A.
Publication of WO2019057843A1 publication Critical patent/WO2019057843A1/en

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/54—Testing for continuity
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/52—Testing for short-circuits, leakage current or ground faults
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/58—Testing of lines, cables or conductors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/28—Testing of electronic circuits, e.g. by signal tracer
    • G01R31/282—Testing of electronic circuits specially adapted for particular applications not provided for elsewhere
    • G01R31/2829—Testing of circuits in sensor or actuator systems

Definitions

  • the present invention generally relates to diagnosing the status of electronic sensors, e.g. for use in automotive applications, and more particularly to a method and system for wire interruption detection for guarded sensors.
  • a passive component is used inside the sensor, between the sense and the guard electrode. A DC voltage is applied to the two sensor cables and the current through the passive component is determined.
  • a guard node is unbalanced to create a voltage difference between sense and guard electrode. Due to the sense-guard impedance, an additional current can be determined.
  • a problem addressed by the present invention is how to provide an effective method and system for determining whether a sense or guard wire is interrupted or not.
  • the present invention provides a detection unit for detecting an interruption in a guard wire or sense wire coupling a guarded sensor to the detection unit.
  • the detection unit comprises a sense wire output and a guard wire output configured to be coupled, in use, to a sense wire and a guard wire, respectively, and a first EMC filter, the first EMC filter including a sense node and a guard node, each coupled to signal analysis and evaluation circuitry, the first EMC filter having a sense wire output coupled to the sense wire output of the detection unit.
  • the detection unit further comprises a guard DC blocking element coupled between a guard wire output of the first EMC filter and the guard wire output of the detection unit.
  • the detection unit further comprises a guard voltage source, configured to apply a DC voltage to the guard node.
  • the detection unit further comprises a diagnostics voltage source configured to supply an AC voltage signal to a first junction between the guard DC blocking element and the guard wire output of the detection unit.
  • the signal analysis and evaluation circuitry is configured to indicate that the guard wire or sense wire is interrupted if a current out of the sense node, l_Sense_Node, is zero.
  • the diagnostics voltage source is coupled to the first junction via a diagnostics DC blocking element.
  • a second EMC filter is connected between the diagnostics voltage source and the diagnostics DC blocking element.
  • a current-to-voltage converter is coupled across the sense node and a guard node of the first EMC filter.
  • the signal analysis and evaluation circuitry is configured to indicate that the guard wire or sense wire is interrupted if a voltage output by the current-to-voltage converter is zero.
  • the AC voltage signal has a predefined frequency.
  • the signal analysis and evaluation circuitry is configured to operate in a frequency selective manner, whereby the detection unit is insensitive to received currents or voltages at frequencies which are not equal to the predefined frequency.
  • the AC voltage signal is amplitude or frequency modulated.
  • a switching element is arranged between the guard DC blocking element and the guard node of the EMC filter. By opening the switching element, any influence of the EMC filter on the diagnostics circuitry may be entirely eliminated which results in an increased robustness of the detection.
  • a method for detecting an interruption in a guard wire or sense wire coupling a guarded sensor to a detection unit comprises providing a detection unit, the detection unit including a sense wire output and a guard wire output configured to be coupled, in use, to a sense wire and a guard wire, respectively, and a first EMC filter, the first EMC filter including a sense node and a guard node, each coupled to signal analysis and evaluation circuitry, the first EMC filter having a sense wire output coupled to the sense wire output of the detection unit.
  • a guard DC blocking element may be coupled between a guard wire output of the first EMC filter and the guard wire output of the detection unit.
  • the method further comprises applying, using a guard voltage source, a DC voltage to the guard node.
  • the method further comprises supplying, using a diagnostics voltage source, an AC voltage signal to a first junction between the guard DC blocking element and the guard wire output of the detection unit.
  • the method further comprises measuring, using the signal analysis and evaluation circuitry, a current out of the sense node, l_Sense_Node, and indicating, using the signal analysis and evaluation circuitry, that the guard wire or sense wire is interrupted if the current, l_Sense_Node, is zero.
  • the diagnostics voltage source is coupled to the first junction via a diagnostics DC blocking element.
  • a second EMC filter is connected between the diagnostics voltage source and the diagnostics DC blocking element.
  • a current-to-voltage converter is coupled across the sense node and a guard node of the first EMC filter.
  • the method further comprises measuring, using the signal analysis and evaluation circuitry, a voltage output by the current-to-voltage converter and indicating, using the signal analysis and evaluation circuitry, that the guard wire or sense wire is interrupted if a voltage output by the current-to-voltage converter is zero.
  • the AC voltage signal has a predefined frequency; the method further comprising operating the signal analysis and evaluation circuitry in a frequency selective manner, whereby the detection unit is insensitive to received currents or voltages at frequencies which are not equal to the predefined frequency.
  • the AC voltage signal is amplitude or frequency modulated.
  • the invention determines the presence of the sense-guard impedance of a guarded sensor system.
  • An advantage of the invention is that, due to the topology of the circuit, conditions of the measurement circuit/detection unit and leading-in the signal for the detection, this concept is insensitive to component variation and external influences.
  • Advantages thus include the following: due to the topology of the circuit (detection unit) the diagnostics result is not influenced by component variation and tolerance (EMC-, filter components) or external effects (sense-GND load variation, EMC disturbance).
  • EMC- component variation and tolerance
  • EMC disturbance sense-GND load variation
  • Figure 1 schematically illustrates a detection arrangement including a detection unit according to an embodiment of the invention, coupled to a guarded sensor;
  • Figure 2 shows the detection arrangement of Fig. 1 , indicating relevant impedances and current flows.
  • Embodiments of the invention are used to determine a wire interruption of a guarded sensor.
  • FIG. 1 schematically illustrates a detection arrangement 2 including a detection unit 4 according to an embodiment of the invention, in this case in the form of an Electronic Control Unit (ECU), coupled to a guarded sensor 6.
  • a sense wire 8 couples a sense wire output 10 of the detection unit 4 to a sense wire input 12 of the guarded sensor 6, and a guard wire 14 couples a guard wire output 16 of the detection unit 4 to a guard wire input 18 of the guarded sensor 6.
  • ECU Electronic Control Unit
  • the detection unit 4 also includes a first EMC filter 20, the first EMC filter having a sense output 22 coupled to the sense wire output 10 of the detection unit 4 via a sense DC blocking element 24.
  • the first EMC filter 20 also includes a guard output 26 coupled to the guard wire output 16 of the detection unit 4 via a guard DC blocking element 28.
  • the first EMC filter 20 has a sense node 30 and a guard node 32, each coupled to signal analysis and evaluation circuitry 34, as will be described in further detail below.
  • a current-to-voltage converter 36 is coupled across the sense node 30 and a guard node 32 of the first EMC filter 20.
  • the senor 6 has (i) an impendence between the sense wire 8 and ground (GND) designated Z_Sense_GND 40, (ii) an impendence between the guard wire 14 and ground designated Z_Guard_GND 42, and (iii) a sense-guard impedance between the sense wire 8 and the guard wire 14 designated Z_Sense_Guard 44.
  • the wire interruption detection of the sense and/or guard wire is realized indirect by determining Z_Sense_Guard 44.
  • the determination of Z_Sense_Guard 44 is realized by applying an AC signal V2, e.g. from a diagnostics voltage source 46, directly on the guard wire output 16 of the detection unit 4, e.g. to first junction 48 in front of the guard DC blocking element 28, while a DC voltage V1 , e.g. from guard voltage source 50, is applied on the guard node 32.
  • the diagnostics voltage source 46 is coupled to the first junction 48 via a diagnostics DC blocking element 52.
  • a second EMC filter 54 is connected between the diagnostics voltage source 46 and the diagnostics DC blocking element 52.
  • the DC blocking elements described herein may comprise a capacitor.
  • the current to voltage converter 36 mirrors the DC voltage V1 to the sense node 30. Due to DC block (by sense DC blocking element 24 and guard DC blocking element 28) on sense and guard, a DC current flow to the sense output 22 and guard output 26 is not possible and the right side of each of the sense DC blocking element 24 and guard DC blocking element 28 is AC-wise grounded.
  • the Figure 2 shows the AC current flow during the diagnostics.
  • the source of the diagnostics current is the voltage source 46 (V2) which applies the AC signal.
  • V2 voltage source 46
  • the current l_Diagnostics_Source is divided into the AC current (l_Guard_Wire) via the guard wire 14 and the AC current (l_Guard_Node) which flows into the guard node 32.
  • the diagnostics signal is applied on the left side of the guard DC blocking element 28. Due to this, the impedance of the guard DC blocking element 28 in the guard node 32 is present and acts to divide the diagnostics AC current l_Diagnostics_Source into two parts.
  • l_Guard_Node flows into the guard node 32 and a second AC current l_Guard_Wire flows via the guard wire 14 into the sensor 6.
  • a second characteristic of this embodiment is that the guard node 32 and also the sense node 30 are AC-wise grounded. Consequently, an AC current flow via the impedances of the first EMC filter 20 from sense to guard or from guard to Ground is negligible/neglectable. This means that the current l_Guard_Node is not influenced by variation of the EMC filter components.
  • the current l_Guard_Wire which flows into the sensor 6 will be divided into two currents.
  • One current (l_Guard_GND) which flows via Z_Guard_GND 42 to ground and a second current (l_Guard_Sense) which flows via Z_Sense_Guard 44 to sense.
  • This current (l_Guard_Sense) will be divided again in two parts.
  • One current (l_Sense_GND) which flows via Z_Sense_GND 40 ground and a second current (l_Sense_Wire) which flows via the sense wire 8 and to the impedance of the sense DC blocking element 24 of the detection unit 4.
  • the current to voltage converter 36 mirrors the AC ground to the sense node 30. A current flow from the sense node 30 to the guard node 32 is neglectable. This means that the current l_Sense_Node through the current to voltage converter 36 is equal to the current l_Sense_Wire and is not influenced by the first EMC filter 20.
  • the final current, which is converted into a voltage by the current to voltage converter 36, is the current l_Sense_Node.
  • This voltage is analysed and evaluated by the signal analysis and evaluation circuitry 34 to determine the sense-guard impedance (Z_Sense_Guard) 44 and diagnose the wire interruption in that way. It can be easily seen that the current l_Sense_Node depends on the impedance Z_Sense_Guard. In the event that the sense wire 8 or guard wire 14 is interrupted, the current l_Sense_Node is zero.
  • Another characteristic of this embodiment is that, due to the topology of the diagnostics circuit, the notional impedances Z_Sense_GND and Z_Guard_GND do not influence the current l_Sense_Wire, which is analysed and leads to the diagnostics result.
  • the only impedance which can influence the current l_Sense_Wire, is the impedance of the DC blocking elements 24, 28 and 52 (Z_DC_Block).
  • the AC signal of the diagnostics signal source 46 has a predefined frequency.
  • the analysis of the current l_Sense_Node by diagnostics circuitry comprising the current to voltage converter 36 and the signal analysis and evaluation circuitry 34 is configured to be frequency selective as well. This makes the techniques according to this embodiment insensitive to frequencies which are not equal to the predefined (diagnostics) frequency.
  • modulation methods such as amplitude modulation or frequency modulation can be used in the AC signal.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measurement Of Current Or Voltage (AREA)
  • Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)

Abstract

A detection unit (4) for detecting an interruption in a guard wire (14) or sense wire (8) coupling a guarded sensor (6) to the detection unit (4). The detection unit (4) comprises a sense wire output (10) and a guard wire output (16) configured to be coupled, in use, to a sense wire (8) and a guard wire (14), respectively, and a first EMC filter (20), the first EMC filter including a sense node (30) and a guard node (32), each coupled to signal analysis and evaluation circuitry (34), the first EMC filter (20) having a sense wire output (10) coupled to the sense wire output (10) of the detection unit(4). The detection unit further comprises a guard DC blocking element (28) coupled between a guard wire output (16) of the first EMC filter (20) and the guard wire output (16) of the detection unit (4). A guard voltage source(50) is configured to apply a DC voltage to the guard node (32), and a diagnostics voltage source (46) is configured to supply an AC voltage signal to a first junction (48) between the guard DC blocking element (28) and the guard wire output (16) of the detection unit (4). The signal analysis and evaluation circuitry (34) is configured to indicate that the guard wire (14) or sense wire (8) is interrupted if a current out of the sense node (30), I_Sense_Node, is zero.The detection unit (4) includes a current-to- voltage converter (36) coupled across the sense node (30) and a guard node (32), whereby the signal analysis and evaluation circuitry (34) is configured to indicate that the guard wire (14) or sense wire (8) is interrupted if a voltage output by the current- to-voltage converter (36) is zero.A corresponding detection method is also disclosed.

Description

Method and System for Wire Interruption Detection for Guarded Sensors Technical field
[0001 ] The present invention generally relates to diagnosing the status of electronic sensors, e.g. for use in automotive applications, and more particularly to a method and system for wire interruption detection for guarded sensors.
Background of the Invention
[0002] For safety reasons, it is necessary to detect a wire interruption of a guarded sensor. To do this, several methods can be used.
[0003] In one known technique, a passive component is used inside the sensor, between the sense and the guard electrode. A DC voltage is applied to the two sensor cables and the current through the passive component is determined.
[0004] In another known technique, two additional wires shorted to the sense and guard electrode are used to determine the loop connection.
[0005] In another known technique, a guard node is unbalanced to create a voltage difference between sense and guard electrode. Due to the sense-guard impedance, an additional current can be determined.
[0006] Another example, in document US 2016/169953 A1 , discloses a system for wire breakage detection in temperature sensor systems.
[0007] However, a difficulty is to determine only the sense-guard impedance without influences from other components (EMC-, filter components, tolerances) or external effects (sense-GND load variation, EMC disturbance). With known diagnostics techniques it is not possible to detect an interruption for all given conditions.
Object of the invention
[0008] A problem addressed by the present invention is how to provide an effective method and system for determining whether a sense or guard wire is interrupted or not. General Description of the Invention
[0009] In order to overcome the abovementioned problems, the present invention provides a detection unit for detecting an interruption in a guard wire or sense wire coupling a guarded sensor to the detection unit. The detection unit comprises a sense wire output and a guard wire output configured to be coupled, in use, to a sense wire and a guard wire, respectively, and a first EMC filter, the first EMC filter including a sense node and a guard node, each coupled to signal analysis and evaluation circuitry, the first EMC filter having a sense wire output coupled to the sense wire output of the detection unit. The detection unit further comprises a guard DC blocking element coupled between a guard wire output of the first EMC filter and the guard wire output of the detection unit. The detection unit further comprises a guard voltage source, configured to apply a DC voltage to the guard node. The detection unit further comprises a diagnostics voltage source configured to supply an AC voltage signal to a first junction between the guard DC blocking element and the guard wire output of the detection unit. The signal analysis and evaluation circuitry is configured to indicate that the guard wire or sense wire is interrupted if a current out of the sense node, l_Sense_Node, is zero.
[0010] Preferably, the diagnostics voltage source is coupled to the first junction via a diagnostics DC blocking element. Preferably, a second EMC filter is connected between the diagnostics voltage source and the diagnostics DC blocking element.
[001 1 ] In one embodiment, a current-to-voltage converter is coupled across the sense node and a guard node of the first EMC filter. Preferably, the signal analysis and evaluation circuitry is configured to indicate that the guard wire or sense wire is interrupted if a voltage output by the current-to-voltage converter is zero.
[0012] Preferably, the AC voltage signal has a predefined frequency. Preferably, the signal analysis and evaluation circuitry is configured to operate in a frequency selective manner, whereby the detection unit is insensitive to received currents or voltages at frequencies which are not equal to the predefined frequency.
[0013] In one embodiment, the AC voltage signal is amplitude or frequency modulated. [0014] In a possible embodiment, a switching element is arranged between the guard DC blocking element and the guard node of the EMC filter. By opening the switching element, any influence of the EMC filter on the diagnostics circuitry may be entirely eliminated which results in an increased robustness of the detection.
[0015] According to another aspect of the invention there is provided a method for detecting an interruption in a guard wire or sense wire coupling a guarded sensor to a detection unit. The method comprises providing a detection unit, the detection unit including a sense wire output and a guard wire output configured to be coupled, in use, to a sense wire and a guard wire, respectively, and a first EMC filter, the first EMC filter including a sense node and a guard node, each coupled to signal analysis and evaluation circuitry, the first EMC filter having a sense wire output coupled to the sense wire output of the detection unit. A guard DC blocking element may be coupled between a guard wire output of the first EMC filter and the guard wire output of the detection unit. The method further comprises applying, using a guard voltage source, a DC voltage to the guard node. The method further comprises supplying, using a diagnostics voltage source, an AC voltage signal to a first junction between the guard DC blocking element and the guard wire output of the detection unit. The method further comprises measuring, using the signal analysis and evaluation circuitry, a current out of the sense node, l_Sense_Node, and indicating, using the signal analysis and evaluation circuitry, that the guard wire or sense wire is interrupted if the current, l_Sense_Node, is zero.
[0016] Preferably, the diagnostics voltage source is coupled to the first junction via a diagnostics DC blocking element. Preferably, a second EMC filter is connected between the diagnostics voltage source and the diagnostics DC blocking element.
[0017] In one embodiment, a current-to-voltage converter is coupled across the sense node and a guard node of the first EMC filter. Preferably, the method further comprises measuring, using the signal analysis and evaluation circuitry, a voltage output by the current-to-voltage converter and indicating, using the signal analysis and evaluation circuitry, that the guard wire or sense wire is interrupted if a voltage output by the current-to-voltage converter is zero.
[0018] Preferably, the AC voltage signal has a predefined frequency; the method further comprising operating the signal analysis and evaluation circuitry in a frequency selective manner, whereby the detection unit is insensitive to received currents or voltages at frequencies which are not equal to the predefined frequency.
[0019] In one embodiment, the AC voltage signal is amplitude or frequency modulated.
[0020] The invention determines the presence of the sense-guard impedance of a guarded sensor system.
[0021 ] An advantage of the invention is that, due to the topology of the circuit, conditions of the measurement circuit/detection unit and leading-in the signal for the detection, this concept is insensitive to component variation and external influences.
[0022] Advantages, at least in embodiments, thus include the following: due to the topology of the circuit (detection unit) the diagnostics result is not influenced by component variation and tolerance (EMC-, filter components) or external effects (sense-GND load variation, EMC disturbance).
Brief Description of the Drawings
[0023] Further details and advantages of the present invention will be apparent from the following detailed description of not limiting embodiments with reference to the attached drawing, wherein:
Figure 1 schematically illustrates a detection arrangement including a detection unit according to an embodiment of the invention, coupled to a guarded sensor; and
Figure 2 shows the detection arrangement of Fig. 1 , indicating relevant impedances and current flows.
Description of Preferred Embodiments
[0024] In the following, like numerals will be used to indicate like elements.
[0025] Embodiments of the invention are used to determine a wire interruption of a guarded sensor.
[0026] Figure 1 schematically illustrates a detection arrangement 2 including a detection unit 4 according to an embodiment of the invention, in this case in the form of an Electronic Control Unit (ECU), coupled to a guarded sensor 6. In use, a sense wire 8 couples a sense wire output 10 of the detection unit 4 to a sense wire input 12 of the guarded sensor 6, and a guard wire 14 couples a guard wire output 16 of the detection unit 4 to a guard wire input 18 of the guarded sensor 6.
[0027] In this embodiment, the detection unit 4 also includes a first EMC filter 20, the first EMC filter having a sense output 22 coupled to the sense wire output 10 of the detection unit 4 via a sense DC blocking element 24. The first EMC filter 20 also includes a guard output 26 coupled to the guard wire output 16 of the detection unit 4 via a guard DC blocking element 28.
[0028] The first EMC filter 20 has a sense node 30 and a guard node 32, each coupled to signal analysis and evaluation circuitry 34, as will be described in further detail below. In this embodiment, a current-to-voltage converter 36 is coupled across the sense node 30 and a guard node 32 of the first EMC filter 20.
[0029] At least as viewed conceptually, the sensor 6 has (i) an impendence between the sense wire 8 and ground (GND) designated Z_Sense_GND 40, (ii) an impendence between the guard wire 14 and ground designated Z_Guard_GND 42, and (iii) a sense-guard impedance between the sense wire 8 and the guard wire 14 designated Z_Sense_Guard 44.
[0030] In embodiments, the wire interruption detection of the sense and/or guard wire is realized indirect by determining Z_Sense_Guard 44.
[0031 ] The determination of Z_Sense_Guard 44 is realized by applying an AC signal V2, e.g. from a diagnostics voltage source 46, directly on the guard wire output 16 of the detection unit 4, e.g. to first junction 48 in front of the guard DC blocking element 28, while a DC voltage V1 , e.g. from guard voltage source 50, is applied on the guard node 32. Preferably, the diagnostics voltage source 46 is coupled to the first junction 48 via a diagnostics DC blocking element 52. In this embodiment, a second EMC filter 54 is connected between the diagnostics voltage source 46 and the diagnostics DC blocking element 52. In each case, the DC blocking elements described herein may comprise a capacitor.
[0032] In operation, the current to voltage converter 36 mirrors the DC voltage V1 to the sense node 30. Due to DC block (by sense DC blocking element 24 and guard DC blocking element 28) on sense and guard, a DC current flow to the sense output 22 and guard output 26 is not possible and the right side of each of the sense DC blocking element 24 and guard DC blocking element 28 is AC-wise grounded.
[0033] The Figure 2 shows the AC current flow during the diagnostics. The source of the diagnostics current is the voltage source 46 (V2) which applies the AC signal. Via the impedance of the guard DC blocking element 28 the current l_Diagnostics_Source is divided into the AC current (l_Guard_Wire) via the guard wire 14 and the AC current (l_Guard_Node) which flows into the guard node 32. One characteristic of this embodiment is that the diagnostics signal is applied on the left side of the guard DC blocking element 28. Due to this, the impedance of the guard DC blocking element 28 in the guard node 32 is present and acts to divide the diagnostics AC current l_Diagnostics_Source into two parts. One part l_Guard_Node flows into the guard node 32 and a second AC current l_Guard_Wire flows via the guard wire 14 into the sensor 6. A second characteristic of this embodiment is that the guard node 32 and also the sense node 30 are AC-wise grounded. Consequently, an AC current flow via the impedances of the first EMC filter 20 from sense to guard or from guard to Ground is negligible/neglectable. This means that the current l_Guard_Node is not influenced by variation of the EMC filter components.
[0034] The current l_Guard_Wire which flows into the sensor 6 will be divided into two currents. One current (l_Guard_GND) which flows via Z_Guard_GND 42 to ground and a second current (l_Guard_Sense) which flows via Z_Sense_Guard 44 to sense.
[0035] This current (l_Guard_Sense) will be divided again in two parts. One current (l_Sense_GND) which flows via Z_Sense_GND 40 ground and a second current (l_Sense_Wire) which flows via the sense wire 8 and to the impedance of the sense DC blocking element 24 of the detection unit 4.
[0036] Due to the fact that the guard node 32 is AC-wise grounded, the current to voltage converter 36 mirrors the AC ground to the sense node 30. A current flow from the sense node 30 to the guard node 32 is neglectable. This means that the current l_Sense_Node through the current to voltage converter 36 is equal to the current l_Sense_Wire and is not influenced by the first EMC filter 20. [0037] The final current, which is converted into a voltage by the current to voltage converter 36, is the current l_Sense_Node. This voltage is analysed and evaluated by the signal analysis and evaluation circuitry 34 to determine the sense-guard impedance (Z_Sense_Guard) 44 and diagnose the wire interruption in that way. It can be easily seen that the current l_Sense_Node depends on the impedance Z_Sense_Guard. In the event that the sense wire 8 or guard wire 14 is interrupted, the current l_Sense_Node is zero.
[0038] Another characteristic of this embodiment is that, due to the topology of the diagnostics circuit, the notional impedances Z_Sense_GND and Z_Guard_GND do not influence the current l_Sense_Wire, which is analysed and leads to the diagnostics result. The only impedance which can influence the current l_Sense_Wire, is the impedance of the DC blocking elements 24, 28 and 52 (Z_DC_Block).
[0039] In one embodiment of the invention, the AC signal of the diagnostics signal source 46 has a predefined frequency. As a consequence, the analysis of the current l_Sense_Node by diagnostics circuitry comprising the current to voltage converter 36 and the signal analysis and evaluation circuitry 34 is configured to be frequency selective as well. This makes the techniques according to this embodiment insensitive to frequencies which are not equal to the predefined (diagnostics) frequency.
[0040] In another embodiment, for dealing with the case of sensitivity to remaining external disturbances, modulation methods such as amplitude modulation or frequency modulation can be used in the AC signal.
List of Reference Symbols
2 detection arrangement
4 detection unit
6 sensor
8 sense wire
10 sense wire output
12 sense wire input
14 guard wire
16 guard wire output
18 guard wire input
20 EMC filter
22 sense output
24 sense DC blocking element
26 guard output
28 guard DC blocking element
30 sense node
32 guard node
34 signal analysis and evaluation circuitry
36 current-to-voltage converter
40 Z_Sense_GND
42 Z_Guard_GND
44 Z_Sense_Guard
46 diagnostics voltage source
48 first junction
50 guard voltage source
52 diagnostics DC blocking element
54 EMC filter

Claims

Claims
1 . A detection unit (4) for detecting an interruption in a guard wire (14) or sense wire (8) coupling a guarded sensor (6) to the detection unit (4), the detection unit comprising: - a sense wire output (10) and a guard wire output (16) configured to be coupled, in use, to a sense wire (8) and a guard wire (14), respectively,
- a signal analysis and evaluation circuitry (34);
- a first EMC filter (20), the first EMC filter (20) including a sense node (30) and a guard node (32), each coupled to the signal analysis and evaluation circuitry (34), the first EMC filter (20) having a sense wire output (22) coupled to the sense wire output (10) of the detection unit (4);
- a guard DC blocking element (28) coupled between a guard wire output (26) of the first EMC filter (20) and the guard wire output (16) of the detection unit (4);
- a guard voltage source (50), configured to apply a DC voltage to the guard node (32); and
- a diagnostics voltage source (46) configured to supply an AC voltage signal to a first junction (48) between the guard DC blocking element (28) and the guard wire output (16) of the detection unit (4);
wherein the signal analysis and evaluation circuitry (34) is configured to indicate that the guard wire (14) or sense wire (8) is interrupted if a current out of the sense node (30), l_Sense_Node, is zero.
2. The detection unit (4) according to claim 1 , wherein the diagnostics voltage source (46) is coupled to the first junction (48) via a diagnostics DC blocking element (52).
3. The detection unit (4) according to claim 2, wherein a second EMC filter (54) is connected between the diagnostics voltage source (46) and the diagnostics DC blocking element (52).
4. The detection unit (4) according to claim 1 or 2, wherein a current-to-voltage converter (36) is coupled across the sense node (30) and a guard node (32) of the first EMC filter (20).
The detection unit (4) according to claim 4, wherein the signal analysis and evaluation circuitry (34) is configured to indicate that the guard wire (14) or sense wire (8) is interrupted if a voltage output by the current-to-voltage converter (36) is zero.
The detection unit (4) according to any of the preceding claims, wherein the AC voltage signal has a predefined frequency.
The detection unit (4) according to claim 6, wherein the signal analysis and evaluation circuitry (34) is configured to operate in a frequency selective manner, whereby the detection unit (4) is insensitive to received currents or voltages at frequencies which are not equal to the predefined frequency.
The detection unit (4) according to any of the preceding claims, wherein the AC voltage signal is amplitude or frequency modulated.
A method for detecting an interruption in a guard wire (14) or sense wire (8) coupling a guarded sensor (6) to a detection unit (4), the method comprising:
- providing a detection unit (4), the detection unit including
- a sense wire output (10) and a guard wire output (16) configured to be coupled, in use, to a sense wire (8) and a guard wire (14), respectively,
- a signal analysis and evaluation circuitry (34);
- a first EMC filter (20), the first EMC filter including a sense node (30) and a guard node (32), each coupled to the signal analysis and evaluation circuitry (34), the first EMC filter (20) having a sense wire output (22) coupled to the sense wire output (10) of the detection unit (4);
- a guard DC blocking element (28) coupled between a guard wire output (16) of the first EMC filter (20) and the guard wire output (16) of the detection unit (4);
- applying, using a guard voltage source (50), a DC voltage to the guard node (32); and
- supplying, using a diagnostics voltage source (46), an AC voltage signal to a first junction (48) between the guard DC blocking element (28) and the guard wire output (16) of the detection unit (4);
- measuring, using the signal analysis and evaluation circuitry (34), a current out of the sense node (30), l_Sense_Node; and - indicating, using the signal analysis and evaluation circuitry (34), that the guard wire (14) or sense wire (8) is interrupted if the current, l_Sense_Node, is zero.
10. The method according to claim 9, wherein the diagnostics voltage source (46) is coupled to the first junction (48) via a diagnostics DC blocking element (52).
1 1 . The method according to claim 10, wherein a second EMC filter (54) is connected between the diagnostics voltage source (46) and the diagnostics DC blocking element (52).
12. The method according to claim 9 or 10, wherein a current-to-voltage converter (36) is coupled across the sense node (30) and a guard node (32) of the first EMC filter (20).
13. The method according to claim 12, further comprising measuring, using the signal analysis and evaluation circuitry (34), a voltage output by the current-to- voltage converter (36) and indicating, using the signal analysis and evaluation circuitry (34), that the guard wire (14) or sense wire (8) is interrupted if a voltage output by the current-to-voltage converter (36) is zero.
14. The method according to any of claims 9 to 13, wherein the AC voltage signal has a predefined frequency; the method further comprising operating the signal analysis and evaluation circuitry (34) in a frequency selective manner, whereby the detection unit (4) is insensitive to received currents or voltages at frequencies which are not equal to the predefined frequency.
15. The method according to any of the preceding claims, wherein the AC voltage signal is amplitude or frequency modulated.
PCT/EP2018/075520 2017-09-22 2018-09-20 Method and system for wire interruption detection for guarded sensors WO2019057843A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
LU100452A LU100452B1 (en) 2017-09-22 2017-09-22 Method and System for Wire Interruption Detection for Guarded Sensors
LULU100452 2017-09-22

Publications (1)

Publication Number Publication Date
WO2019057843A1 true WO2019057843A1 (en) 2019-03-28

Family

ID=60001974

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2018/075520 WO2019057843A1 (en) 2017-09-22 2018-09-20 Method and system for wire interruption detection for guarded sensors

Country Status (2)

Country Link
LU (1) LU100452B1 (en)
WO (1) WO2019057843A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2020207989A1 (en) * 2019-04-10 2020-10-15 Iee International Electronics & Engineering S.A. Multi-channel capacitance sensing measurement circuit
LU101255B1 (en) * 2019-05-29 2020-11-30 Iee Sa Multi-Channel Capacitance Sensing Measurement Circuit

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090273350A1 (en) * 2008-05-02 2009-11-05 Siemens Energy & Automation, Inc. Systems and Methods for Detecting Wire Breaks
US20150346259A1 (en) * 2014-05-27 2015-12-03 GM Global Technology Operations LLC Method and apparatus for open-wire fault detection and diagnosis in a controller area network
US20160077128A1 (en) * 2012-10-11 2016-03-17 Tektronix, Inc. Automatic probe ground connection checking techniques
US20160169953A1 (en) 2013-06-28 2016-06-16 Pr Electronics A/S System and method for detection of wire breakage

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090273350A1 (en) * 2008-05-02 2009-11-05 Siemens Energy & Automation, Inc. Systems and Methods for Detecting Wire Breaks
US20160077128A1 (en) * 2012-10-11 2016-03-17 Tektronix, Inc. Automatic probe ground connection checking techniques
US20160169953A1 (en) 2013-06-28 2016-06-16 Pr Electronics A/S System and method for detection of wire breakage
US20150346259A1 (en) * 2014-05-27 2015-12-03 GM Global Technology Operations LLC Method and apparatus for open-wire fault detection and diagnosis in a controller area network

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2020207989A1 (en) * 2019-04-10 2020-10-15 Iee International Electronics & Engineering S.A. Multi-channel capacitance sensing measurement circuit
US20220155355A1 (en) * 2019-04-10 2022-05-19 Iee International Electronics & Engineering S.A. Multi-channel capacitance sensing measurement circuit
LU101255B1 (en) * 2019-05-29 2020-11-30 Iee Sa Multi-Channel Capacitance Sensing Measurement Circuit

Also Published As

Publication number Publication date
LU100452B1 (en) 2019-03-29

Similar Documents

Publication Publication Date Title
US8294474B2 (en) Device for sensing a fault current in a field bus system
US10793097B2 (en) Capacitive measurement circuit with sensor wiring diagnostics
US7633179B2 (en) Passenger detection apparatus for detecting breakage on shield line without being affected by peripheral shield cables
EP2857850A1 (en) HRG ground fault detector and method
WO2019057843A1 (en) Method and system for wire interruption detection for guarded sensors
US11009557B2 (en) Method and device for short-circuit monitoring of a three-phase load
US6628123B2 (en) Method for controlling a transducer device in level sensors and device for carrying out such a method
US10132651B2 (en) Capacitive sensing system with hardware diagnostics concept for detection of sensor interruption
US11050422B2 (en) Diagnostics for capacitive sensor
US20220155355A1 (en) Multi-channel capacitance sensing measurement circuit
US5734269A (en) Bridge circuit fault monitoring apparatus using an output signal level from a bridge circuit and a power source current level to determine faults
US6145107A (en) Method for early failure recognition in power semiconductor modules
US6313741B1 (en) Fault detection circuit for sensors
US5579235A (en) Method of monitoring rpm sensors
CN108353011A (en) Bus system and method for diagnosing short circuit
LU500033B1 (en) Low-Cost, Protected Capacitive Sensing Circuit for Loading Mode Operation of Capacitive Sensors Employing Heater Members
US11391763B2 (en) System for grounding and diagnostics
LU101255B1 (en) Multi-Channel Capacitance Sensing Measurement Circuit
LU100737B1 (en) Diagnostics for Capacitive Sensor
US11530956B2 (en) Capacitive sensor arrangement
US10877064B2 (en) Evaluation circuit for a capacitive acceleration sensor and device for detecting an acceleration
CN114270327A (en) Method for identifying the position of a bus subscriber
EP3404928A1 (en) Improved electronic unit for controlling fire sensors
LU100745B1 (en) System for Grounding and Diagnostics
JPH04242174A (en) Trouble discriminator for detector

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 18769731

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 18769731

Country of ref document: EP

Kind code of ref document: A1