CN110058153B

CN110058153B - Relay monitoring device

Info

Publication number: CN110058153B
Application number: CN201811553619.XA
Authority: CN
Inventors: R·施皮尔格; J·赖特尔
Original assignee: Heidelberger Druckmaschinen AG
Current assignee: Heidelberger Druckmaschinen AG
Priority date: 2018-01-19
Filing date: 2018-12-19
Publication date: 2023-02-03
Anticipated expiration: 2038-12-19
Also published as: DE102018221059A1; CN110058153A

Abstract

The invention relates to a device for monitoring the functionality of at least one switch (Rel-L1, rel-N, rel-PE), wherein an alternating voltage signal (U) is fed via a signal generator (S) and at least one capacitor (C2) _Tr1 ) Coupled into the current path of the switch (Rel-PE) to be monitored, wherein the alternating voltage signal (U) is fed via at least one further capacitor (C1) _Tr1 ) The output is coupled again for detecting an output voltage (U-out), wherein the output voltage (U-out) is absent when the at least one switch (Rel-PE) is closed. The invention is characterized in that the alternating voltage signal (U) _Tr1 ) Are coupled out by other monitoring devices (FI) for the circuit.

Description

Relay monitoring device

Technical Field

The invention relates to a method for monitoring the functionality of at least one switch

Wherein an alternating voltage signal is coupled in via a signal generator and at least one capacitor into the current path of the switch to be monitored, wherein the alternating voltage signal is coupled out again via at least one further capacitor for detecting the output voltage, wherein the output voltage is not present when the at least one switch is closed.

Background

Such a device for monitoring the functionality of at least one switch according to the classification is known from the publication DE 10 2015 211 A1. In this publication, a device for monitoring the functionality, in particular of a relay, is described, which device determines: whether the relay is completely disengaged. For safety reasons, the functionality of the relays which are important must be checked in order to ensure that the circuit can be completely disconnected from the power grid. In addition, the safety function is also applied to a charging device and a charging cable of an electric vehicle. Since in the case of relays there is the following danger: high temperatures occur during frequent switching operations, in particular during high currents, which result in the switching contacts being welded to one another at least in some areas. This welding causes the relay to no longer open completely and the circuit can therefore no longer be completely disconnected. This safety risk is avoided by means of a device for monitoring the functionality of at least one switch, by permanently testing the relay for its functionality. For this purpose, the device uses a signal generator which couples an alternating voltage signal into the current path of the relay to be monitored via at least one capacitor. Furthermore, the ac voltage signal can be coupled out again by means of at least one further capacitor for detecting the output voltage. The circuit is designed such that the output voltage is present only when the relay is open and is absent when the relay is closed. This means that the output voltage can only be detected when the switch is open. If the signal generator for example fails, there will be no output voltage and therefore the following signals are issued: the switch is not opened and there is a safety issue. Therefore, the circuit has the following advantages: on the one hand, the functionality of the relay is monitored and the circuit itself is safe, since the signal generator required for this also leads to a missing output voltage in the event of a failure, which is therefore likewise signaled to the user. In the case of a missing output voltage, the circuit and the associated devices and apparatuses are not allowed to operate.

Disclosure of Invention

The device for monitoring the functionality of the at least one switch requires a signal generator for this purpose. However, this signal generator is an additional cost factor, which is not negligible in the case of relatively inexpensive circuits and associated devices. The task is therefore to monitor the switch for functionality, without having to provide an additional signal generator for the purpose of monitoring the switch.

According to the invention, this object is achieved by claim 1. Advantageous embodiments of the invention can be gathered from the dependent claims and the drawings. According to the invention, the ac voltage signal for checking the functionality of the at least one switch is not generated by its own signal generator, but is coupled out by a further monitoring device for the circuit. Usually, a monitoring device is already present in the circuit, which likewise uses the ac voltage signal for checking the determined state. The monitoring device is a so-called "fluxgate" sensor, by means of which the magnetic field generated, for example, by means of an electrical line can be measured. These sensors are based on: two coils are applied to a ring-shaped magnetizable object. Here, a so-called driver winding and a so-called sensor winding are provided. The driver winding is periodically supplied with an alternating voltage signal and the magnetic core is continuously re-magnetized. The sensor winding outputs an induced voltage. In this case, the voltage of the driver winding and the output voltage of the sensor are in a defined relationship. If a magnetic object or a line through which a current with a magnetic field flows is now introduced into the sensor, the output voltage changes and the magnetic field can be determined from the difference between the original output voltage and the changed output voltage. This principle is used, for example, in the case of so-called FI circuit breakers, which can reliably detect ac and dc fault currents and interrupt the voltage for safety reasons. In the present invention, now: the output voltage of the FI protective switch or the output voltage tapped off by the further winding is used to generate an alternating voltage signal which is supplied to the circuit in which the switch to be monitored is arranged. In this way, the ac voltage signal of the signal generator of the prior art can be replaced by the output signal of the other monitoring device, in particular the output signal of the FI protective switch.

In a further embodiment of the invention, it is possible for the signal generator of the further monitoring device for the circuit to couple out an ac voltage signal. Instead of using the output signal of the FI protection switch as the output signal of the second winding or of an additional third winding, the coupled-in signal of the FI protection switch can also be used directly, and therefore the signal generator of the FI protection switch can also be used as the signal generator of the device for monitoring the functionality of at least one switch.

In a particularly advantageous embodiment of the invention, it is provided that the further monitoring device and the device for monitoring the functionality of the at least one switch are arranged together in the charging device or in the charging cable. In this case, at least one signal generator can be omitted in a charging cable or charging device, in particular for charging a battery of an electric vehicle, by using the output signal of the FI protective switch, which is required for safety reasons, for example, for checking at least one further switch (e.g., a relay) for functionality. This significantly reduces the construction costs of the corresponding safety-related circuit for charging an electric vehicle.

Drawings

The invention is further described and illustrated below with reference to the several figures.

Fig. 1 shows a circuit diagram of an apparatus for monitoring the functionality of three switches arranged in parallel in a line, a zero line and a protective line of a voltage supply device according to the prior art;

fig. 2 shows a circuit diagram of an apparatus according to the invention for monitoring the functionality of three switches arranged in parallel in a line, a zero line and a protective line of a voltage supply with a combined signal generator.

Detailed Description

Fig. 1 shows a section of a voltage supply device, which is part of a charging device for a battery of an electric vehicle, for example, according to the prior art. In the event of a defect in the charging device, the latter must be reliably disconnected from the voltage supply of the power grid. This is achieved in fig. 1 by means of three relays — Rel-L1 in the line L1, rel-N in the zero line N and Rel-PE in the protection line PE. In this way, the line L1, the zero line N and the protection line PE can all be decoupled from the voltage supply of the charging device and therefore the current flow between the network charging devices can be reliably suppressed. However, this can only be ensured if the relay functions reliably. It must be ensured in particular that: the relay is reliably disconnected in order to suppress the voltage supply. Fig. 1 shows a transformer T, the primary winding Tr of which an ac voltage signal can be coupled in. The alternating voltage signal is generated by a signal generator S, which in turn can be part of the charging device, and the alternating voltage signal of the signal generator, for example for controlling a semiconductor component in a switching power supply, comes from the control electronics of the charging device.

The line L1, the zero line N and the protection line PE are connected to the secondary winding Tr1 via capacitors C2, C3, C4, respectively, so that the ac voltage of the signal generator S can be coupled via the capacitors C2, C3, C4 into the switch without an electrical connection between the lines L1, N, PE having to be present. This ac voltage is coupled out again via a further capacitor C1 and is transmitted to a photo coupler 1, which is connected to a diode D1 connected in parallel in the blocking direction. The left-hand circuit can likewise be completely galvanically isolated from the right-hand low-voltage region by the optocoupler 1.

If all switches Rel-L1, rel-N, rel-PE are open, only a small voltage drops across resistor R1 and current flows through the optocoupler. The output voltage U-out can thus be determined at the output of the optocoupler. This means that all switches Rel-L1, rel-N and Rel-PE are always open and therefore always reliably disconnected, when the output voltage U-out can be determined on the output on the right side. If only one of the three switches Rel-L1, rel-N, rel-PE is closed, the entire voltage drops across the resistor R1 and no current flows through the optocoupler 1. This results in: there is no output voltage U-out on the output.

The same effect occurs if the signal generator S is defective and no ac voltage is coupled in at all via the transformer winding Tr. Then likewise no current flows through the optocoupler 1 and no output voltage U-out is present. This means, on the other hand, that an output voltage U-out is present if on the one hand all switches Rel-L1, rel-N, rel-PE are disconnected and on the other hand the signal generator S is active and feeds an alternating voltage. In this case, the following can be used: the relay operates normally and the ac voltage of the signal generator S is actually present. Thus, in any case, the absence of the output voltage U-out indicates a fault, either the signal generator S is defective or the switches Rel-L1, rel-N and Rel-PE are not separated. In any case, a fault is present and a corresponding warning is output in the charging device. Thus, only one single signal generator S is required for monitoring the three relays Rel-L1, rel-N and Rel-PE, but also any number of further relays can be monitored in parallel. Further, the lead line L1 and the zero lead line N are electrically separated by capacitors C3, C4.

In the case where electromagnetic interference occurs due to the alternating voltage of the signal generator S, the alternating voltage may turn on and off the alternating voltage of the signal generator S through the switch Ts. It can thus be achieved that the alternating voltage is only briefly switched on at certain time intervals by means of the switch Ts in order to carry out the testing of the switches Rel-L1, rel-N and Rel-PE and thus limit the electromagnetic incompatibility to a minimum.

Fig. 2 shows a device according to the invention, which is based on the device in fig. 1. In this case, the signal generator S present in fig. 1 is omitted and the voltage U of the secondary winding is tapped off at the secondary winding Tr1 of the FI protective switch FI _Tr1 . The FI protection switch FI itself has its own signal generator S _FI The signal generator is required for the operation mode of the FI protection switch FI. The FI protective switch FI is used to compare the current in a line, for example line L1, zero line N or protective line PE, and to disconnect the circuit from the power grid if a reliable current difference is exceeded. According to the invention, an AC voltage U is now coupled out by an FI protection switch FI _Tr1 The alternating voltage is used to check the functionality of the relays Rel-L1 to Rel-N and of the relays Rel-PE. Since the FI protection switch FI must be present for safety reasons, in particular in the case of charging devices and charging cables for electric vehicles, the signal generator S required in the prior art in fig. 1 can be omitted and the signal coupled out by the FI protection switch FI instead. In this way, the costs for the safety technology of the charging cable and the charging device of the electric vehicle can be significantly reduced in other devices.

List of reference numerals

1. Photoelectric coupler

L1 conductor

N-zero conductor

FI FI protection switch

PE protection wire

Relay in Rel-L1 conductor

Relay in Rel-N zero conductor

Relay in Rel-PE protection wire

Tr primary winding

Tr1 Secondary winding

T-shaped transformer

C1, C2, C3, C4, C10 capacitor

D1 Diode with a high-voltage source

R1, R2 and R5 resistors

U-out output voltage

U _Tr1 Voltage of secondary winding

S signal generator

S _FI Signal generator of FI protection switch

TS switch

Supply voltage of VCC photocoupler

Claims

1. Device for monitoring the functionality of at least one switch, wherein an alternating voltage signal is coupled in by means of at least one capacitor into the current path of the switch to be monitored, wherein the alternating voltage signal is coupled out again by means of at least one further capacitor for detecting an output voltage, wherein no output voltage is present when the at least one switch is closed, characterized in that the alternating voltage signal is coupled out by a signal generator for a further monitoring device of the circuit.

2. The apparatus of claim 1, wherein the other monitoring device has a secondary coil coupled to output the alternating voltage signal.

3. An apparatus according to claim 1 or 2, characterized in that the further monitoring means has a third coil which is coupled out of the alternating voltage signal.

4. Device according to claim 1 or 2, characterized in that the other monitoring means is a FI protection switch.

5. An arrangement according to claim 1 or 2, characterized in that the further monitoring means and the arrangement according to claim 1 or 2 are arranged together in a charging device or charging cable.