DE102016208719B4 - An active electrical energy source monitoring system and method for monitoring an active electrical energy source - Google Patents

Abstract

The invention relates to a monitoring system for an active electrical energy source (1) in an analog electrical circuit (10), wherein the active electrical energy source (1) is electrically coupled to a first shunt resistor (R1) having different states, each having different resistance values and the active electrical energy source (1) is also electrically coupled to a second shunt resistor (R2) having a fixed resistance so that a current or voltage change in the electrical circuit (10) can be detected by a detector system (11) If the first shunt resistor (R1) changes state, and that depending on the detected change in the electrical circuit (10), a monitoring signal (S) for the active electrical energy source (1) can be automatically generated. It also refers to a surveillance procedure.

Description

The invention relates to a monitoring system for an active electrical energy source with the features of claim 1 and a method for monitoring an active electrical energy source with the features of claim 10.

Active electrical energy sources, such as power or voltage sources, are used in many technical fields. An example are transducers in stationary or mobile gas detection systems. In this application, the transducers must be monitored for proper operation. In a digital system this can be done relatively easily e.g. B. be achieved by introducing checksums for the signals.

In the DE 10 2008 043 178 A1 a field device is described whose current signal is subjected to monitoring. The US 2005/0168343 A1 describes the monitoring of a 4 to 20 mA sensor circuit, whereby an error monitoring is realized.

The test for analog connections with static signals is more difficult. Solutions in this regard are presented below, which include a monitoring system for an active electrical energy source in an analog electrical circuit, wherein the active electrical energy source is coupled to at least a first shunt resistor, which can assume different states, each with different resistance values. A current or voltage change in the electrical circuit may be detected by a detection system if the first shunt resistor changes state, and in response to the detected change in the electrical circuit, a monitoring and / or response signal for the active electrical energy source is automatically generated ,

By using an adjustable first shunt resistor, different operating states (i.e., different resistance values having an effect on the electrical parameters within the electrical circuit) can be generated that can be used to effectively generate a monitor signal.

The active electrical energy source is also coupled to at least one second fixed resistance resistor. This makes the electrical circuit design more flexible since the first shunt resistor does not have to accommodate the entire electrical load.

The at least one first shunt resistor and the at least one second shunt resistor are connected in parallel or in series. This arrangement allows an efficient circuit design. The states of the first shunt resistor can be changed by setting the resistance value (in the case of parallel connection) or by bypassing (in the case of series connection).

The adjustable first shunt resistor is a variable resistor, in particular a potentiometer or a connectable resistor. The connectable resistance can z. B. be realized by being connected by a switch to the electrical circuit. With these embodiments, the two (or more) resistivity states can be efficiently generated.

In one embodiment, the current in the electrical circuit is in the range of 4 to 20 mA according to the Namur NE 43 standard. This current range is generally z. B. used in the process and the security industry.

In one embodiment, the active electrical energy source comprises a transmitter device. A transmitter device is understood here to receive a non-standard measuring signal and to convert it into a standard measuring range. In particular, the active electrical energy source comprises a sensor device such as a temperature sensor, a humidity sensor, a pressure sensor, a light sensor, a force sensor, a gas detection sensor in a stationary or mobile gas detection system, a sensor of the wind speed and direction, a sound sensor, a pH sensor and / or a radioactivity sensor.

In another embodiment, the detection system (eg, a microcontroller) detects a change in the form of a current or voltage measurement, and a computing unit calculates current or voltage values based on the voltage and current measurements, such that the monitor signal is a function of the calculated Current or voltage values is generated.

In addition, the detection system and / or the arithmetic unit can be coupled to a control unit, in particular a microcontroller. In particular, the detection system and / or the computing unit are software systems, in particular embedded with the microcontroller.

It is also possible that, depending on the monitoring signal, an operating condition, in particular an error / non-error condition is generated and in particular on the Based on the monitoring signal an automatic control action is generated. Therefore, the detection of an unwanted operating condition z. B. used to automatically turn off a sensor unit.

The problem is also solved by a method according to claim 10.

In this case, the active electrical energy source is electrically coupled to at least one first shunt resistor, which can assume different states, each with different resistance values. The first shunt resistance is therefore considered adjustable.

• a) werden mindestens zwei Spannungs- oder Strommessungen mit dem ersten Nebenwiderstand, der in verschiedenen Zuständen ist, vorgenommen und
• b) die Spannungs- und Strommessungen werden verwendet, um Stromwerte für die verschiedenen Zustände zu berechnen, und
• c) ein Überwachungssignal für die aktive elektrische Energiequelle wird erzeugt.

Then

• a) at least two voltage or current measurements are made with the first shunt which is in different states and
• b) the voltage and current measurements are used to calculate current values for the different states, and
• c) a monitoring signal for the active electrical energy source is generated.

In one embodiment of the method, the active electrical energy source is also electrically coupled to the at least one second shunt resistor having a fixed resistance.

• a) einen ersten Überwachungszustand, wenn die Stromwerte, die aus den Spannungsmessungen (U1_R2, U1_R1||R2) berechnet werden, Folgendes sind:
  
  mit

  U1_R1:

  Spannung über dem Nebenwiderstand R2

  U1_R1||R2:

  Spannung in der Leitung mit den Nebenwiderständen R1, R2 parallel

  R1:

  Widerstandswert des ersten Nebenwiderstands R1

  R2:

  Widerstandswert des zweiten Nebenwiderstands R2

  R1||R2:

  Widerstandswert der parallelen Nebenwiderstände R1, R2

• b) und einen zweiten Überwachungszustand, wenn
  
  mit

  U1_R1:

  Spannung über dem Nebenwiderstand R2

  U1_R1||R2:

  Spannung in der Leitung mit den Nebenwiderständen R1, R2 parallel

  R1:

  Widerstandswert des ersten Nebenwiderstands R1

  R2:

  Widerstandswert des zweiten Nebenwiderstands R2

  R1||R2:

  Widerstandswert der parallelen Nebenwiderstände R1, R2

In an alternative embodiment, the supervisory signal takes the following:

• a) a first monitoring state when the current values calculated from the voltage measurements (U1 _R2 , U1 _{R1 || R2} ) are:
  
  With

  U1 _R1:

  Voltage across shunt R2

  U1 _{R1 || R2} :

  Voltage in the line with shunt resistors R1, R2 in parallel

  R1:

  Resistance value of the first shunt resistor R1

  R2:

  Resistance value of the second shunt resistor R2

  R1 || R2:

  Resistance value of the parallel shunt resistors R1, R2

• b) and a second monitoring state when
  
  With

  U1 _R1 :

  Voltage across shunt R2

  U1 _{R1 || R2} :

  Voltage in the line with shunt resistors R1, R2 in parallel

  R1:

  Resistance value of the first shunt resistor R1

  R2:

  Resistance value of the second shunt resistor R2

  R1 || R2:

  Resistance value of the parallel shunt resistors R1, R2

• a) einen ersten Überwachungszustand, wenn die Stromwerte, die aus den Spannungsmessungen (U1_R2, U1_R1||R2) berechnet werden, Folgendes sind:
  
• b) und einen zweiten Überwachungszustand, wenn
  
  mit

  U1_R1:

  Spannung über dem Nebenwiderstand R2

  U1_R1||R2:

  Spannung in der Leitung mit den Nebenwiderständen R1, R2 parallel

  R1:

  Widerstandswert des ersten Nebenwiderstands R1

  R2:

  Widerstandswert des zweiten Nebenwiderstands R2

  R1||R2:

  Widerstandswert der parallelen Nebenwiderstände R1, R2

If noise is considered, the equations should be replaced by the following set of equations. The monitoring signal takes the following:

• a) a first monitoring state when the current values calculated from the voltage measurements (U1 _R2 , U1 _{R1 || R2} ) are:
  
• b) and a second monitoring state when
  
  With

  U1 _R1 :

  Voltage across shunt R2

  U1 _{R1 || R2} :

  Voltage in the line with shunt resistors R1, R2 in parallel

  R1:

  Resistance value of the first shunt resistor R1

  R2:

  Resistance value of the second shunt resistor R2

  R1 || R2:

  Resistance value of the parallel shunt resistors R1, R2

It is also possible that in one embodiment of the method, a plurality of current or voltage measurements are made before and after the change of the resistance value in the first shunt resistor.

Hereinafter, some embodiments of the invention are described in an exemplary manner.

1 shows a transmitter connection according to the prior art;

2 shows a transmitter connection with a first embodiment of the invention;

3 shows a transmitter connection with a second embodiment of the invention;

4 shows a transmitter connection with a third embodiment of the invention.

In 1 is an embodiment of active electrical energy sources 1 (shown here as power sources), the z. B. encoders, with sensor devices 20 which operate with signals in the range of 4 mA to 20 mA, which is the industry standard (Namur NE 43). It is the job of the transmitter to collect data through the sensor devices 20 be measured (eg, gas sensor concentration data, temperature data, pressure data, etc.) into current signals in a normalized range.

A sensor error is signaled by expanding the range of the signal from 4 mA to 20 mA. If the current z. Below 3.6 mA or above 21 mA, this is interpreted as a sensor error. To avoid false alarms, the signal should be present for at least 4 seconds before being interpreted as a sensor error.

The output current signal of the transmitter 1 is proportional to the transmitted value. To obtain the final measurement value, the transmitted value must be measured and then scaled to the final measurement value.

1 shows an exemplary circuit with three conductive lines, each having the line resistance value R _cable . All lines are with the sensor device 20 , such as a gas sensor, connected.

As an example in 1 2, the transmitted current is normally measured by a voltmeter U1 with a shunt resistor R2 having a constant and well known resistance. This shunt resistor R1 is connected to a line in the electrical circuit 10 connected, ie with the transmitter 1 connected.

The voltage U1, which is measured via the shunt resistor R2, can be mathematically converted into a current by Ohm's law, since the resistance of the shunt resistor R2 is known.

In the embodiment which is in 1 is shown, the three lines include connectors 30 , The electrical circuit 10 to the right of the connectors 30 is a part of a control unit that includes the power source between the top two wires. The electrical circuit 10 to the left of the connectors 30 includes the active electrical energy source 1 ie the transmitter.

In 2 an embodiment of a monitoring system is shown which controls the operation of the power driver from a control unit 40 supervised. In this embodiment, the active electrical energy source 1 Here, a transmitter, electrically coupled to a first shunt resistor R1, which may have different states with different corresponding resistance values. In the embodiment shown, the first shunt resistor R1 is connectable by a switch, ie, the first shunt resistor R1 may assume a fixed relatively low resistance value and a very high resistance value than the two different states. The connectable first shunt resistor R1 is just one embodiment of an adjustable resistor. Further examples of an adjustable resistor R1 are given below.

The active source of electrical energy 1 is also coupled to a second shunt resistor R2 having a fixed resistance. In this case, both shunt resistors R1, R2 are connected in parallel. In a further embodiment ( 4 ), the shunt resistors R1, R2 are connected in series.

When the state of the first shunt resistor R1 changes, that is, the resistivity changes, the change of a current or a voltage change (here in the upper line of the circuit 10 ) by a detector system 11 be detected with the control unit 40 is coupled.

Depending on the detected change, a monitoring signal S for the active electrical energy source 1 through the control unit 40 generated during the control of the transmitter 1 can be used. The monitoring signal S may be an error / non-error signal.

The basic idea of the approach is that, if the shunt resistance in the first shunt resistor R1 is changed, the current driver must change the drive voltage to reach an unchanged current to allow for a properly operating transmitter guarantee. This voltage change is predictable and can be monitored.

To implement a test for the correct operation of the current driver of the transmitter, the control unit system must measure U1 at least twice to generate at least two states. Once opened with the switch of the first shunt resistor R1 (non-conductive) and once closed with the switch (conductive). Because of Ohm's law, these two measured values must satisfy the following equation in a first state

In a second monitoring state then applies

The calculation is done by a computing unit 12 performed with the control unit 40 is coupled. On the basis of this difference, the monitoring signal S for the active electrical energy source 1 which can be used in the control of the transmitter.

It is understood that the above calculation is for parallel shunt resistors and for measured voltage data. An analogue calculation can be performed for shunt resistors in series and / or for measured current values.

When noise is considered, the equations given above are not strictly true. In these cases, the following inequalities are valid.

sind. A first monitoring state is assumed when the current values calculated from the voltage measurements (U1 _R2 , U1 _{R1 || R2} ),

are.

The threshold ε depends on the noise that is expected. Consequently, the second monitoring state is given by

In 3 is an alternative embodiment to that in the context of 2 shown embodiment. Here, the first shunt resistor R1 is not switchable, but a potentiometer. Therefore, the first shunt resistor R1 can change a continuous range of resistance values. Otherwise, the functionality of the monitoring system and the monitoring method are analogous to the embodiment described above.

Although, in principle, one set of measurements of the voltage is sufficient for the purpose of monitoring, several measurements can be made over time. The voltage U1 _R2 across the second shunt R2 can be measured at least once before or after the measurement of U1 _{R1 || R2} . If all measurements do not agree with equality (or in the face of inequality noise), discard the test because a changing current is to be assumed.

In a variant, a certain threshold for contradicting measurements may be defined.

It is understood that the above calculation is for parallel shunt resistors and for measured voltage data. An analogue calculation can be performed for shunt resistors in series and / or for measured current values.

In the embodiments that are in 2 and 3 are shown, two parallel shunt resistors R1, R2 are used. In an alternative embodiment, more than two shunt resistors R1, R2 are used.

In 4 An alternative embodiment for a monitoring system or monitoring method is shown. 4 is analogous to 2 so that reference to the relevant description can be made. Here are the shunt resistors R1, R2 in series. The first shunt resistor R1 can be connected or disconnected by a switch. The changes in the current or voltage measurement caused by activating or deactivating the switch may be made by the control unit 40 can be detected and can generate the monitoring signal S. Both shunt resistors R1, R2 are between the measuring lead and ground.

In an alternative variant of the embodiment of 4 ie, with resistors R1, R2 in series, the first shunt resistor could be a potentiometer.

In addition, in 2 to 4 Embodiments of the transmitter with three conductive lines shown. In alternative embodiments, transducers with two or more than three lines are possible.

LIST OF REFERENCE NUMBERS

1

active electrical energy source (voltage source, power source)

10

electrical circuit

11

detection system

12

computer unit

20

sensor device

30

Interconnects

40

control unit

R1

first shunt resistor (adjustable, connectable)

R2

second shunt resistance (fixed resistance)

S

heartbeat

U1

Voltage measurement device

U1 _R2

Voltage with only the second shunt in the circuit

U1 _{R1 || R2}

 Voltage with the first and the second shunt in parallel

Claims (14)

Monitoring system for an active electrical energy source ( 1 ) in an analog electrical circuit ( 10 ), wherein the active electrical energy source ( 1 ) is electrically coupled to at least one first shunt resistor (R1), which can assume different states, each with different resistance values, so that a current or voltage change in the electrical circuit ( 10 ) by a detection system ( 11 ) can be detected if the first shunt resistor (R1) changes state, and in dependence on the detected change in the electrical circuit ( 10 ) a monitoring signal (S) for the active electrical energy source ( 1 ) is generated automatically, wherein the active electrical energy source ( 1 ) is electrically coupled to at least one second shunt resistor (R2) having a fixed resistance value, wherein the at least one first shunt resistor (R1) and the at least one second shunt resistor (R2) are connected in parallel or in series, and wherein the at least one first shunt resistor ( R1) is a variable resistor. A monitoring system according to claim 2, wherein the at least one first shunt resistor (R1) is a potentiometer or a connectable resistor. Monitoring system according to claim 1 or 2, wherein the current in the electrical circuit ( 10 ) according to the Namur NE 43 standard in the range of 4 to 20 mA. Monitoring system according to one of the preceding claims, wherein the active electrical energy source ( 1 ) comprises a transmitter device. A monitoring system according to claim 4, wherein the active electrical energy source ( 1 ) a sensor device ( 20 ), in particular a temperature sensor, a humidity sensor, a pressure sensor, a light sensor, a force sensor, a gas detection sensor in a stationary or mobile gas detection system, a sensor of the wind speed and direction, a sound sensor, a pH sensor and / or a radioactivity sensor. Monitoring system according to one of the preceding claims, wherein the detection system ( 11 ) detects a change in the form of a current or voltage measurement, wherein the detection system ( 11 ) with a computing unit ( 12 ) to calculate current or voltage values based on the current or voltage measurements, such that the monitor signal (S) is generated in response to the calculated current or voltage values. Monitoring system according to at least one of the preceding claims, wherein the detection system ( 11 ) and / or the arithmetic unit ( 12 ) with a control unit, in particular a microcontroller ( 40 ) is coupled. Monitoring system according to at least one of the preceding claims, wherein the detection system ( 11 ) and / or the arithmetic unit ( 12 ) Software systems, in particular embedded with the microcontroller ( 40 ), are. Monitoring system according to at least one of the preceding claims, wherein in response to the monitoring signal (S) an operating condition, in particular an error / non-error condition is generated and in particular an automatic control action based on this monitoring signal (S) is generated. Monitoring method for an active electrical energy source ( 1 ) in an electrical circuit ( 10 ), wherein the active electrical energy source ( 1 ) is coupled to at least one first shunt resistor (R1), which can assume different states, each with different resistance values, and a) at least two voltage or current measurements (U1 _R2 , U1 _{R1 || R2} ) with the first shunt resistance (R1) in different B) the voltage or current measurements (U1 _R2 , U1 _{R1 || R2} ) can be used to measure current or current Calculate voltage values for the different states, and c) a monitoring signal (S) for an active electrical energy source ( 1 ) is produced. A monitoring method according to claim 10, wherein the active electrical energy source ( 1 ) is also coupled to at least one second shunt resistor (R2) having a fixed resistance value. The monitoring method of claim 11, wherein at least one first shunt resistor (R1) is connected in parallel with at least one shunt resistor (R2) and the monitor signal (S) assumes: a) a first monitor state when the current values obtained from the voltage measurements (U1 _R2 , U1 _{R1 || R2} ), are:

b) and a second monitoring state when

A monitoring method according to claim 11, wherein the active electrical energy source ( 1 ) is also coupled to at least one second shunt resistor (R2) having a fixed resistance and the monitor signal (S) assumes: a) a first monitor state when the current values calculated from the voltage measurements (U1 _R2 , U1 _{R1 || R2} ) are, the following are:

b) and a second monitoring state when

A monitoring method according to at least one of claims 10 to 13, wherein a plurality of voltage or current measurements (U1 _R2 , U1 _{R1 || R2} ) are made before and after the change in resistance in the first shunt resistor (R1).

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