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DE-102014211981-B4 - Monitoring circuit for an electrical circuit and motor vehicle

DE102014211981B4DE 102014211981 B4DE102014211981 B4DE 102014211981B4DE-102014211981-B4

Abstract

Monitoring circuit (2) for an electrical circuit, in particular for a high-voltage electrical system (1) of a motor vehicle, wherein the electrical circuit comprises a battery (7) having two poles, at least one electrical load (10) connectable to the battery (7) and a first relay (8) arranged between a first pole of the battery (7) and the at least one electrical load (10) for interrupting the electrical connection of the battery (7) with the at least one electrical load (10), characterized in that the monitoring circuit (2) is arranged in parallel to the battery (7) and comprises a signal output device (3, 13) and a first switch (4), wherein the first switch (4) in a first position forms an electrical connection of the monitoring circuit (2) with a contact of the first relay (8) facing the first pole of the battery (7) and wherein the first switch (4) in a second position forms an electrical connection of the monitoring circuit (2) with a contact of the first relay (8) facing away from the first pole of the battery (7).

Inventors

  • Thomas Lehnst

Assignees

  • VOLKSWAGEN AKTIENGESELLSCHAFT

Dates

Publication Date
20260513
Application Date
20140623

Claims (10)

  1. Monitoring circuit (2) for an electrical circuit, in particular for a high-voltage electrical system (1) of a motor vehicle, wherein the electrical circuit comprises a battery (7) having two poles, at least one electrical load (10) connectable to the battery (7) and a first relay (8) arranged between a first pole of the battery (7) and the at least one electrical load (10) for interrupting the electrical connection of the battery (7) with the at least one electrical load (10), characterized in that the monitoring circuit (2) is arranged in parallel to the battery (7) and comprises a signal output device (3, 13) and a first switch (4), wherein the first switch (4) in a first position forms an electrical connection of the monitoring circuit (2) with a contact of the first relay (8) facing the first pole of the battery (7) and wherein the first switch (4) in a second position forms an electrical connection of the monitoring circuit (2) with a contact of the first relay (8) facing away from the first pole of the battery (7).
  2. Monitoring circuit (2) according to Claim 1 , wherein the electrical circuit (1) includes a second relay (9) arranged between a second terminal of the battery (7) and the at least one electrical consumer (10) to interrupt the electrical connection of the battery (7) with the at least one electrical consumer (10) comprises, characterized in that the monitoring circuit (2) has a second switch (5), wherein the second switch (5) in a first position forms an electrical connection of the monitoring circuit (2) with a contact of the second relay (9) facing the second pole of the battery (7) and wherein the second switch (5) in a second position forms an electrical connection of the monitoring circuit (2) with a contact of the second relay (9) facing away from the second pole of the battery (7).
  3. Monitoring circuit (2) according to Claim 2 , characterized in that the first switch (4) and the second switch (5) are combined into a common switch with four switching positions, wherein the four switching positions correspond to the four possibilities of combining the first and second positions of the first and second switches (4, 5).
  4. Monitoring circuit (2) according to one of the preceding claims, characterized in that the signal output device (3, 13) comprises a light source (3), wherein the light source (3) in particular comprises or consists of a light-emitting diode (13).
  5. Monitoring circuit (2) according to one of the preceding claims, characterized in that a second signal output device (13') is arranged in parallel to the signal output device (3, 13).
  6. Monitoring circuit (2) according to one of the preceding claims, characterized in that the monitoring circuit (2) comprises an electronic circuit (14) for controlling the signal output device (3, 13, 13').
  7. Monitoring circuit (2) according to one of the preceding claims, characterized in that the monitoring circuit (2) comprises a manually actuated test button (15), wherein the test button (15) in the actuated state establishes an electrical connection between the contact points of the first and second position of the first switch (4) and an electrical connection between the contact points of the first and second position of the second switch (5).
  8. Monitoring circuit (2) according to one of the preceding claims, characterized in that the monitoring circuit (2) is designed as a replaceable component (12) and preferably has a housing (12) with electrical contacts (11) arranged on the outside.
  9. Motor vehicle with a high-voltage electrical system (1) and a monitoring circuit (2) according to one of the preceding claims.
  10. motor vehicle with a high-voltage electrical system (1) and a monitoring circuit (2) according to Claim 8 , characterized in that the monitoring circuit has electrical contacts (11) for contacting mating contacts of the high-voltage electrical system (1), wherein all mating contacts of the high-voltage electrical system (1) are connected to the high-voltage electrical system (1) via a series resistor (6).

Description

The invention relates to a monitoring circuit for an electrical circuit, in particular for a high-voltage electrical system of a motor vehicle, and to a motor vehicle. Modern motor vehicles are often equipped with high-voltage electrical systems. A high-voltage electrical system is defined as any electrical system whose voltage exceeds the 12 V to 14 V of a conventional vehicle electrical system. Motor vehicles powered exclusively or partially by electric motors (e.g., electric or hybrid vehicles) typically have high-voltage electrical systems with voltages between 100 V and 600 V, usually between 300 V and 400 V. Conventionally powered motor vehicles can also have a high-voltage electrical system in addition to the standard 12 V system, in which case the voltage of the high-voltage system is often in the range of 40 V to 100 V. In particular, high-voltage electrical systems with nominal voltages of 42 V or 48 V are known in the art. All of the aforementioned high-voltage electrical systems share the common requirement that, due to their high voltage, they must be protected against accidental contact between live parts and people. In particular, it must be ensured that maintenance or repair work on the high-voltage electrical system is only carried out when the system is completely de-energized. This generally requires three steps. The first step is to de-energize the high-voltage electrical system. This is done by disconnecting the power source. The power source is typically a high-voltage battery that provides DC voltage. Alternatively or additionally, the high-voltage electrical system can be powered by other power sources. A DC/DC converter can serve as an additional power source, converting the voltage of another electrical system, such as a low-voltage system, into a voltage suitable for the high-voltage system. An external power source, such as a charging station, can also be used. This can supply either DC or AC voltage, which feeds the high-voltage electrical system either directly or via an intermediate charger. The connection to the power source can be made manually, for example, by operating a switch or disconnecting a plug. Relays or contactors are usually located at the terminals of the high-voltage battery, which switch the electrical connection on or off depending on a control current. In the second step, the high-voltage electrical system is secured against reconnection. Methods for securing a high-voltage electrical system against reconnection are described, for example, in the published patent applications. DE 10 2012 015 060 A1 and DE 10 2012 015 059 A1 known. The third step involves verifying the absence of voltage. Various methods for verifying the absence of voltage in a high-voltage electrical system are known in the art. One possibility is to require a trained specialist to manually measure the voltage at several points within the high-voltage system and record the measured voltage absence in a report. However, this procedure is time-consuming and requires extensive training. DE 10 2011 122 420 A1 Proposes a method for the automated detection of the absence of voltage. In this method, at least two control units of a high-voltage system independently measure the voltage. The absence of voltage is indicated by a display unit only if the participating control units detect a voltage below a threshold value. DE 10 2011 109 707 A1 Proposes a display method that determines whether a voltage is present on a vehicle's high-voltage electrical system. Depending on this determination, a signal is output that is perceptible outside the vehicle. An optical indicator, which is active when a vehicle's electrical system is connected to a power source and therefore functional, also reveals the JP 11-266502 . DE 10 2010 045 501 A1 Disclosing a motor vehicle with a high-voltage electrical system and a high-voltage source. A signal output device emits a signal when the high-voltage source is disconnected from the high-voltage electrical system. No signal is emitted when the high-voltage source is connected to the high-voltage electrical system. Based on the prior art, the task is to provide a simple, safe, and reliable monitoring circuit for an electrical circuit, in particular for the high-voltage electrical system of a motor vehicle. Such a high-voltage electrical system known in the prior art discloses, for example, the following: DE 10 2010 041 018 A1 in their 1 . The problem is solved using a monitoring circuit and a motor vehicle with the features of the independent claims. Advantage Legally relevant further training courses are subject to dependent claims. A monitoring circuit according to the invention is suitable for an electrical circuit, in particular for a high-voltage electrical system of a motor vehicle, wherein the electrical circuit comprises a battery having two poles, at least one electrical load connectable to the battery, and a first relay arranged between a first pole of the battery