WO2013034249A2 - Method for detecting a connection fault - Google Patents

Method for detecting a connection fault Download PDF

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Publication number
WO2013034249A2
WO2013034249A2 PCT/EP2012/003542 EP2012003542W WO2013034249A2 WO 2013034249 A2 WO2013034249 A2 WO 2013034249A2 EP 2012003542 W EP2012003542 W EP 2012003542W WO 2013034249 A2 WO2013034249 A2 WO 2013034249A2
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WO
WIPO (PCT)
Prior art keywords
voltage
low
voltage output
converter
motor vehicle
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Application number
PCT/EP2012/003542
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German (de)
French (fr)
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WO2013034249A3 (en
Inventor
Tommy BEYER
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Audi Ag
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Publication date
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Publication of WO2013034249A2 publication Critical patent/WO2013034249A2/en
Publication of WO2013034249A3 publication Critical patent/WO2013034249A3/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L3/00—Electric devices on electrically-propelled vehicles for safety purposes; Monitoring operating variables, e.g. speed, deceleration or energy consumption
    • B60L3/0023—Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train
    • B60L3/003—Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train relating to inverters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L3/00—Electric devices on electrically-propelled vehicles for safety purposes; Monitoring operating variables, e.g. speed, deceleration or energy consumption
    • B60L3/0023—Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train
    • B60L3/0069—Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train relating to the isolation, e.g. ground fault or leak current
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L58/00—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
    • B60L58/10—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries
    • B60L58/18—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries of two or more battery modules
    • B60L58/20—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries of two or more battery modules having different nominal voltages
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0047—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with monitoring or indicating devices or circuits
    • H02J7/0048—Detection of remaining charge capacity or state of charge [SOC]
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/14—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries for charging batteries from dynamo-electric generators driven at varying speed, e.g. on vehicle
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/70—Energy storage systems for electromobility, e.g. batteries

Definitions

  • the high-voltage vehicle electrical system has an operating voltage of about 400 V and is used to supply the electric drive units.
  • the low-voltage on-board electrical system is usually operated with 12 V and supplies small consumers such as control units, servomotors and the like.
  • connection faults between the DC-DC converter and the low-voltage on-board network occur, the consumers of the low-voltage on-board network can only be supplied from the low-voltage battery.
  • connection failures can be triggered, for example, by cable damage on the low-voltage side of the DC-DC converter, by fuse defects or the like. Since charging of the low-voltage battery from the high-voltage vehicle electrical system is no longer possible due to the connection failure, this discharges quickly in this case, so that the supply of control units, servomotors and the like is at risk. Such a connection must therefore be detected quickly to allow safe operation of the motor vehicle.
  • the present invention is therefore an object of the invention to provide a method of the type mentioned, by means of which a reliable detection of connection interference between a low-voltage output of a DC-DC converter and a low-voltage vehicle electrical system of a motor vehicle is possible.
  • a voltage at the low-voltage output of a DC-DC converter to ground, a voltage at a low-voltage battery to ground and a current flow at the low-voltage output of the DC-DC converter is measured. If an absolute value of the difference of the measured voltages exceeds a first threshold value and at the same time the measured current falls below a second threshold value, then a connection fault between the low-voltage output of the DC-DC converter and the low-voltage on-board network is detected.
  • the first threshold 1.5V and the second threshold to 5A to avoid misdiagnosis due to naturally occurring voltage and current fluctuations.
  • a periodic implementation of the method is also advantageous. It is particularly expedient to carry out the measurements and evaluation at least once per millisecond. In this way, it is possible to detect disturbances even before the function of the devices powered by the low-voltage on-board electrical system is impaired.
  • a corresponding signal is transmitted to a driver of the motor vehicle when a connection fault is detected.
  • the driver can then take timely action, such as car immobilization, before the link failure can interfere with the proper functioning of the motor vehicle.
  • the single figure shows a schematic representation of an electrical system of an electric motor vehicle.
  • An on-board network 10 of an electric motor vehicle is in a high-voltage board network 12 for supplying an electric drive machine 14 and a low-voltage Volt board network 16, which small consumers, such as controllers and the like.
  • the high voltage vehicle electrical system 12 includes a battery 18 that provides a DC voltage of about 400V and is monitored by a battery controller 20. To supply the drive machine 14, this DC voltage is converted by means of a pulse inverter 22 into a three-phase AC voltage.
  • the high-voltage board network 12 also supplies an air conditioning compressor 24, which is secured by a fuse 26.
  • a battery 28 is also provided, which supplies a DC voltage of 12 V.
  • the negative pole 30 of the battery 28 is connected to ground 32, the positive pole 34 via a line 36 to a terminal 38, via which the consumers of the low-voltage vehicle electrical system are supplied.
  • the low-voltage vehicle electrical system 16 is coupled to the high-voltage on-board electrical system 12 by means of a DC-DC converter 40.
  • the positive low-voltage output 42 of the DC-DC converter is also connected to the terminal 38 via a line 44, in which a fuse, not shown, may be present, the negative low-voltage output 46 of the DC-DC converter is connected to ground 32nd
  • the voltage between the positive low-voltage output 42 of the DC-DC converter 40 and ground 32, as well as the voltage between the positive pole 34 of the battery 28 and ground 32 is measured with sensors not shown in the figure. Furthermore, the current flow at the positive low-voltage output 42 is monitored.
  • the DC-DC converter 40 In the normal state is at the positive low-voltage output 42 and the positive pole 34 of the battery 28, the same voltage, since the two contacts on the Terminal 38 are connected together. Only by possibly different line resistances of the lines 36 and 44, there may be slight differences in voltage. On the other hand, if the line 44 fails, a significant voltage difference occurs between the low-voltage output 42 and the positive pole 34. It is to be distinguished whether the DC-DC converter 40 is active at the time of failure, that is, the vehicle electrical system 12, 16 coupled with each other, or not. If the DC-DC converter 40 is not active, the voltage at the positive low-voltage output 42 breaks down to 0V within about 30 ms after the line 44 has failed, while the voltage at the positive pole 34 of the battery remains constant, at least in the short term. Since the low-voltage output 42 is not supplied from the high-voltage vehicle electrical system 12, no current flows at the low-voltage output 42.
  • the voltage at the positive low-voltage output 42 is maintained by the DC-DC converter 40 after failure of the line 44.
  • the terminal voltage of the battery 28 drops slowly. Due to the interruption of the line 44, no appreciable current flow at the low-voltage output 42 can be measured here as well - if necessary, creeping currents or the like can still occur. In both cases, therefore, a significant difference between the voltage at the low-voltage output 42 and the positive pole 34 of the battery 28 is measured and at the same time a decrease in the current flow at the low-voltage output 42 is observed.
  • a control unit which receives and evaluates the measured values of the sensors can generate a corresponding signal for the driver of the motor vehicle, so that the latter is informed of the condition of his vehicle and can prompt maintenance as soon as possible.
  • a corresponding error code is stored in a fault memory of the motor vehicle. This code can later be read out by the maintenance personnel by means of suitable diagnostic equipment, so that the necessary repairs can be carried out immediately.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Electric Propulsion And Braking For Vehicles (AREA)
  • Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)

Abstract

The invention relates to a method for detecting a connection fault between a low-voltage output of a voltage converter and a low-voltage onboard power supply of a motor vehicle, which involves measuring a voltage at the low-voltage output of the voltage converter to earth, a terminal voltage of a battery in the low-voltage onboard power supply and a current flow at the low-voltage output of the voltage converter. The connection fault is detected when an absolute value of a difference between the measured voltages exceeds a first threshold value and the current flow at the low-voltage output falls below a second threshold value at the same time. This ensures that line breaks, intermittent contacts or the like can be reliably detected without incorrect diagnoses being made as a result of consequential faults.

Description

Verfahren zum Erkennen einer Verbindungsstörung  Method for detecting a connection fault
BESCHREIBUNG: Die Erfindung betrifft ein Verfahren zum Erkennen einer Verbindungsstörung zwischen einem Niedervoltausgang eines Spannungswandlers und einem Niedervoltbordnetz eines Kraftwagens. DESCRIPTION The invention relates to a method for detecting a connection fault between a low-voltage output of a voltage converter and a low-voltage on-board electrical system of a motor vehicle.
Bei Kraftwagen mit elektrischem oder Hybridantrieb sind in der Regel ge- trennte Hochvolt- und Niedervoltbord netze vorgesehen. Das Hochvoltbordnetz weist eine Betriebsspannung von etwa 400 V auf und dient der Versorgung der elektrischen Antriebsaggregate. Das Niedervoltbordnetz wird üblicherweise mit 12 V betrieben und versorgt Kleinverbraucher wie Steuergeräte, Servomotoren und dergleichen. In motor vehicles with electric or hybrid drive, separate high-voltage and low-voltage on-board systems are usually provided. The high-voltage vehicle electrical system has an operating voltage of about 400 V and is used to supply the electric drive units. The low-voltage on-board electrical system is usually operated with 12 V and supplies small consumers such as control units, servomotors and the like.
Beide Bordnetze umfassen eine jeweilige Batterie und sind durch einen Gleichspannungswandler miteinander gekoppelt. Diese Koppelung ermöglicht die Versorgung von Kleinverbrauchern aus der Hochvoltbatterie bzw. das Aufladen der Niedervoltbatterie aus dem Hochvoltbordnetz, beispiels- weise wenn die elektrischen Antriebsaggregate im Hochvoltbordnetz im Generatorbetrieb betrieben werden. Both electrical systems comprise a respective battery and are coupled together by a DC-DC converter. This coupling makes it possible to supply small consumers from the high-voltage battery or to charge the low-voltage battery from the high-voltage on-board electrical system, for example when the electric drive units in the high-voltage on-board electrical system are operated in generator mode.
Treten Verbindungsstörungen zwischen dem Gleichspannungswandler und dem Niedervoltbord netz auf, so können die Verbraucher des Niedervoltbord- netzes nur aus der Niedervoltbatterie versorgt werden. Solche Verbindungsstörungen können beispielsweise durch Kabelschäden auf der Niederspannungsseite des Gleichspannungswandlers, durch Sicherungsdefekte oder dergleichen ausgelöst werden. Da aufgrund der Verbindungsstörung eine Aufladung der Niedervoltbatterie aus dem Hochvoltbordnetz nicht mehr möglich ist, entlädt sich diese in diesem Fall schnell, so dass die Versorgung von Steuergeräten, Servomotoren und dergleichen gefährdet ist. Eine solche Verbindungsstörung muss daher schnell erkannt werden, um einen sicheren Betrieb des Kraftwagens zu ermöglichen. If connection faults between the DC-DC converter and the low-voltage on-board network occur, the consumers of the low-voltage on-board network can only be supplied from the low-voltage battery. Such connection failures can be triggered, for example, by cable damage on the low-voltage side of the DC-DC converter, by fuse defects or the like. Since charging of the low-voltage battery from the high-voltage vehicle electrical system is no longer possible due to the connection failure, this discharges quickly in this case, so that the supply of control units, servomotors and the like is at risk. Such a connection must therefore be detected quickly to allow safe operation of the motor vehicle.
Bekannte Steuerungsverfahren für elektrische Bordnetze von Kraftwagen umfassen zwar eine Überwachung von Spannungen und Stromflüssen in den Bordnetzen, können die geschilderte Art von Verbindungsstörungen jedoch nicht als solche erkennen. Meist wird daher ein Kabelabriss, ein Sicherungsdefekt oder ein Wackelkontakt auf der Niederspannungsseite des Gleichspannungswandlers als Steuergerätefehler fehldiagnostiziert. Diese Diagnose stellt zwar noch immer sicher, dass die Fahrsicherheit gewährleistet bleibt, kann jedoch gegebenenfalls zum Austausch falscher Komponenten bei der Wartung und damit zu hohen und unnötigen Kosten für den Fahrzeughalter führen. Der vorliegenden Erfindung liegt somit die Aufgabe zugrunde, ein Verfahren der eingangs genannten Art anzugeben, mittels welchem eine sichere Erkennung von Verbindungsstörungen zwischen einem Niedervoltausgang eines Gleichspannungswandlers und einem Niedervoltbordnetz eines Kraftwagens ermöglicht wird. Although known control methods for electric vehicle wiring systems of motor vehicles comprise monitoring of voltages and current flows in the on-board networks, they can not recognize the type of connection interference described as such. Therefore, a cable break, a fuse defect or a loose contact on the low-voltage side of the DC-DC converter is usually misdiagnosed as a controller error. Although this diagnosis still ensures that driving safety is guaranteed, it may, however, lead to the replacement of incorrect components during maintenance and thus to high and unnecessary costs for the vehicle owner. The present invention is therefore an object of the invention to provide a method of the type mentioned, by means of which a reliable detection of connection interference between a low-voltage output of a DC-DC converter and a low-voltage vehicle electrical system of a motor vehicle is possible.
Diese Aufgabe wird durch ein Verfahren mit den Merkmalen des Patentanspruchs 1 gelöst. This object is achieved by a method having the features of patent claim 1.
Bei dem erfindungsgemäßen Verfahren wird eine Spannung am Niedervolt- ausgang eines Gleichspannungswandlers gegen Masse, eine Spannung an einer Niedervoltbatterie gegen Masse sowie ein Stromfluss am Niedervoltausgang des Gleichspannungswandlers gemessen. Falls ein Absolutwert der Differenz der gemessenen Spannungen einen ersten Schwellenwert überschreitet und gleichzeitig der gemessene Strom einen zweiten Schwellenwert unterschreitet, so wird eine Verbindungsstörung zwischen dem Niedervoltausgang des Gleichspannungswandlers und dem Niedervoltbordnetz erkannt. In the method according to the invention, a voltage at the low-voltage output of a DC-DC converter to ground, a voltage at a low-voltage battery to ground and a current flow at the low-voltage output of the DC-DC converter is measured. If an absolute value of the difference of the measured voltages exceeds a first threshold value and at the same time the measured current falls below a second threshold value, then a connection fault between the low-voltage output of the DC-DC converter and the low-voltage on-board network is detected.
Da der Niedervoltausgang des Gleichspannungswandlers und der Abgriff der Batterie im Normalzustand des Niedervoltbordnetzes auf gleichem Potential liegen, ist eine Spannungsdifferenz zwischen den genannten Stellen ein Anzeichen für eine Verbindungsstörung. Durch die Überwachung des Stromflusses am Niedervoltausgang des Gleichspannungswandlers wird eine zusätzliche Plausibilisierung erzielt, so dass eine Fehldiagnose aufgrund feh- lerhafter Spannungsmessungen oder aufgrund von Potentialdifferenzen, die trotz intakter Verbindung in Folge von thermisch bedingten Widerstandsschwankungen in den elektrischen Leitungen zwischen Gleichspannungswandler und Batterie auftreten können, zuverlässig vermieden wird. Damit ist sichergestellt, dass Verbindungsstörungen zwischen dem Niedervoltausgang des Gleichspannungswandlers und dem Niedervoltbord netz sicher erkannt werden können. Since the low-voltage output of the DC-DC converter and the tap of the battery in the normal state of the low-voltage on-board network are at the same potential, a voltage difference between said points is an indication of a connection failure. By monitoring the current flow at the low-voltage output of the DC-DC converter, an additional plausibility check is achieved, so that a misdiagnosis due to faulty Lerhafter voltage measurements or due to potential differences that can occur despite intact connection due to thermally induced resistance variations in the electrical lines between DC-DC converter and battery is reliably avoided. This ensures that connection errors between the low-voltage output of the DC-DC converter and the low-voltage on-board network can be reliably detected.
Für übliche Bordnetze ist es zweckmäßig, den ersten Schwellenwert auf 1 ,5 V und den zweiten Schwellenwert auf 5 A festzulegen, um Fehldiagnosen aufgrund natürlich auftretender Spannungs- und Stromschwankungen zu vermeiden. For common vehicle electrical systems, it is appropriate to set the first threshold to 1.5V and the second threshold to 5A to avoid misdiagnosis due to naturally occurring voltage and current fluctuations.
Um Verbindungsstörungen möglichst frühzeitig erkennen zu können, ist fer- ner eine periodische Durchführung des Verfahrens vorteilhaft. Besonders zweckmäßig ist es, die Messungen und Auswertung wenigstens ein mal pro Millisekunde durchzuführen. Auf diese Weise ist es möglich, Störungen zu erkennen, noch bevor die Funktion der vom Niedervoltbordnetz versorgten Geräte beeinträchtigt wird. In order to be able to detect connection disturbances as early as possible, a periodic implementation of the method is also advantageous. It is particularly expedient to carry out the measurements and evaluation at least once per millisecond. In this way, it is possible to detect disturbances even before the function of the devices powered by the low-voltage on-board electrical system is impaired.
In einer weiteren bevorzugten Ausführungsform der Erfindung wird beim Erkennen einer Verbindungsstörung einem Fahrer des Kraftwagens ein entsprechendes Signal übermittelt. Der Fahrer kann dann rechtzeitig Maßnahmen, wie beispielsweise eine Stilliegung des Kraftwagens, ergreifen, bevor die Verbindungsstörung die ordnungsgemäße Funktion des Kraftwagens beeinträchtigen kann. In a further preferred embodiment of the invention, a corresponding signal is transmitted to a driver of the motor vehicle when a connection fault is detected. The driver can then take timely action, such as car immobilization, before the link failure can interfere with the proper functioning of the motor vehicle.
Ferner ist es vorteilhaft, beim Erkennen einer Verbindungsstörung einen diesbezüglichen Eintrag in einem Fehlerspeicher des Kraftwagens vorzu- nehmen. Dieser kann bei der nächsten Wartung des Kraftwagens ausgelesen werden, so dass das Wartungspersonal zuverlässig über die Fehlerquelle informiert wird. Furthermore, it is advantageous to take a relevant entry in a fault memory of the motor vehicle when detecting a connection fault. This can be read at the next maintenance of the motor vehicle, so that the maintenance staff is reliably informed of the source of error.
Im Folgenden wird die Erfindung und ihre Ausführungsformen anhand der Zeichnung näher erläutert. Die einzige Figur zeigt dabei eine schematische Darstellung eines Bordnetzes eines elektrischen Kraftwagens. In the following the invention and its embodiments will be explained in more detail with reference to the drawing. The single figure shows a schematic representation of an electrical system of an electric motor vehicle.
Ein Bord netz 10 eines elektrischen Kraftwagens ist in eine Hochvoltbord netz 12 zur Versorgung einer elektrischen Antriebsmaschine 14 und ein Nieder- voltbordnetz 16, welches Kleinverbraucher, wie beispielsweise Steuergeräte und dgl. versorgt, aufgeteilt. Das Hochvoltbordnetz 12 umfasst eine Batterie 18, die eine Gleichspannung von etwa 400 V zur Verfügung stellt und von einem Batteriesteuergerät 20 überwacht wird. Zur Versorgung der Antriebs- maschine 14 wird diese Gleichspannung mittels eines Pulswechselrichters 22 in eine dreiphasige Wechselspannung gewandelt. Das Hochvoltbord netz 12 versorgt ferner einen Klimakompressor 24, der mittels einer Sicherung 26 abgesichert ist. Im Niedervoltbordnetz 16 ist ebenfalls eine Batterie 28 vorgesehen, welche eine Gleichspannung von 12 V liefert. Der Minuspol 30 der Batterie 28 ist mit Masse 32 verbunden, der Pluspol 34 über eine Leitung 36 mit einer Klemme 38, über welche die Verbraucher des Niedervoltbordnetzes versorgt werden. Um bei niedrigem Ladezustand der Batterie 28 diese neu aufzuladen bzw. die Verbraucher des Niedervoltbordnetzes 16 versorgen zu können, ist das Niedervoltbordnetz 16 mittels eines Gleichspannungswandlers 40 mit dem Hochvoltbordnetz 12 gekoppelt. Der positive Niedervoltausgang 42 des Gleichspannungswandlers ist über eine Leitung 44, in der noch eine nicht gezeigte Sicherung vorhanden sein kann, ebenfalls mit der Klemme 38 verbunden, der negative Niedervoltausgang 46 des Gleichspannungswandlers liegt auf Masse 32. An on-board network 10 of an electric motor vehicle is in a high-voltage board network 12 for supplying an electric drive machine 14 and a low-voltage Volt board network 16, which small consumers, such as controllers and the like. Provided divided. The high voltage vehicle electrical system 12 includes a battery 18 that provides a DC voltage of about 400V and is monitored by a battery controller 20. To supply the drive machine 14, this DC voltage is converted by means of a pulse inverter 22 into a three-phase AC voltage. The high-voltage board network 12 also supplies an air conditioning compressor 24, which is secured by a fuse 26. In low-voltage electrical system 16, a battery 28 is also provided, which supplies a DC voltage of 12 V. The negative pole 30 of the battery 28 is connected to ground 32, the positive pole 34 via a line 36 to a terminal 38, via which the consumers of the low-voltage vehicle electrical system are supplied. In order to recharge the latter at a low state of charge of the battery 28 or to be able to supply the consumers of the low-voltage on-board electrical system 16, the low-voltage vehicle electrical system 16 is coupled to the high-voltage on-board electrical system 12 by means of a DC-DC converter 40. The positive low-voltage output 42 of the DC-DC converter is also connected to the terminal 38 via a line 44, in which a fuse, not shown, may be present, the negative low-voltage output 46 of the DC-DC converter is connected to ground 32nd
Löst sich die Leitung 44 vom positiven Niedervoltausgang 42 oder versagt die Sicherung, so geht die Verbindung zwischen Hochvoltbordnetz 12 und Niedervoltbord netz 16 verloren. Die Verbraucher des Niedervoltbordnetzes 16 können dann nur noch so lange mit Energie versorgt werden, wie die Ladung der Batterie 28 vorhält. Da zu diesen Verbrauchern wichtige Steuergeräte und Servomotoren des Kraftwagens zählen, muss eine solche Unterbre- chung zuverlässig erkannt werden. Dissolves the line 44 from the positive low-voltage output 42 or fails the backup, the connection between high-voltage electrical system 12 and low-voltage electrical network 16 is lost. The consumers of the low-voltage electrical system 16 can then be supplied with energy only as long as the charge of the battery 28 holds. Since these consumers include important control units and servomotors of the motor vehicle, such an interruption must be reliably detected.
Um eine solche Erkennung zu ermöglichen, wird mit in der Figur nicht dargestellten Sensoren die Spannung zwischen dem positiven Niedervoltausgang 42 des Gleichspannungswandlers 40 und Masse 32, sowie die Spannung zwischen dem Pluspol 34 der Batterie 28 und Masse 32 gemessen. Ferner wird der Stromfluss am positiven Niedervoltausgang 42 überwacht. In order to enable such recognition, the voltage between the positive low-voltage output 42 of the DC-DC converter 40 and ground 32, as well as the voltage between the positive pole 34 of the battery 28 and ground 32 is measured with sensors not shown in the figure. Furthermore, the current flow at the positive low-voltage output 42 is monitored.
Im Normalzustand liegt am positiven Niedervoltausgang 42 und dem Pluspol 34 der Batterie 28 die gleiche Spannung an, da die beiden Kontakte über die Klemme 38 miteinander verbunden sind. Lediglich durch gegebenenfalls unterschiedliche Leitungswiderstände der Leitungen 36 und 44 kann es zu geringfügigen Spannungsdifferenzen kommen. Versagt dagegen die Leitung 44, so tritt eine deutliche Spannungsdifferenz zwischen dem Niedervoltausgang 42 und dem Pluspol 34 auf. Hierbei ist zu unterscheiden, ob der Gleichspannungswandler 40 zum Zeitpunkt des Versagens aktiv ist, also die Bordnetze 12, 16 miteinander koppelt, oder nicht. Bei nicht aktivem Gleichspannungswandler 40 bricht nach Versagen der Leitung 44 die Spannung am positiven Niedervoltausgang 42 innerhalb von etwa 30 ms auf 0V zusammen, während die Spannung am Pluspol 34 der Batterie zumindest kurzfristig konstant bleibt. Da der Niedervoltausgang 42 nicht aus dem Hochvoltbordnetz 12 versorgt wird, fließt keinerlei Strom am Nie- dervoltausgang 42. In the normal state is at the positive low-voltage output 42 and the positive pole 34 of the battery 28, the same voltage, since the two contacts on the Terminal 38 are connected together. Only by possibly different line resistances of the lines 36 and 44, there may be slight differences in voltage. On the other hand, if the line 44 fails, a significant voltage difference occurs between the low-voltage output 42 and the positive pole 34. It is to be distinguished whether the DC-DC converter 40 is active at the time of failure, that is, the vehicle electrical system 12, 16 coupled with each other, or not. If the DC-DC converter 40 is not active, the voltage at the positive low-voltage output 42 breaks down to 0V within about 30 ms after the line 44 has failed, while the voltage at the positive pole 34 of the battery remains constant, at least in the short term. Since the low-voltage output 42 is not supplied from the high-voltage vehicle electrical system 12, no current flows at the low-voltage output 42.
Bei aktivem Gleichspannungswandler 40 wird nach Versagen der Leitung 44 die Spannung am positiven Niedervoltausgang 42 durch den Gleichspannungswandler 40 aufrechterhalten. Da im Niedervoltbordnetz 16 weiter Energie verbraucht wird, sinkt jedoch die Klemmenspannung der Batterie 28 langsam ab. Durch die Unterbrechung der Leitung 44 kann auch hier kein nennenswerter Stromfluss am Niedervoltausgang 42 gemessen werden - allenfalls Kriechströme oder dgl. können noch vorkommen. In beiden Fällen wird also eine nennenswerte Differenz zwischen der Spannung am Niedervoltausgang 42 und am Pluspol 34 der Batterie 28 gemessen und gleichzeitig ein Absinken des Stromflusses am Niedervoltausgang 42 beobachtet. Tritt dieser Fall ein, so kann ein Steuergerät, welches die Messwerte der Sensoren empfängt und auswertet, ein entsprechendes Signal für den Fahrer des Kraftwagens erzeugen, so dass diese über den Zustand seines Fahrzeugs informiert wird und baldmöglichst eine Wartung veranlassen kann. Gleichzeitig wird ein entsprechender Fehlercode in einem Fehlerspeicher des Kraftwagens abgelegt. Dieser Code kann später vom Wartungspersonal mittels geeigneter Diagnosegeräte ausgelesen werden, so dass unmit- telbar die notwendigen Reparaturen durchgeführt werden können. With active DC-DC converter 40, the voltage at the positive low-voltage output 42 is maintained by the DC-DC converter 40 after failure of the line 44. As in the low-voltage electrical system 16 more energy is consumed, however, the terminal voltage of the battery 28 drops slowly. Due to the interruption of the line 44, no appreciable current flow at the low-voltage output 42 can be measured here as well - if necessary, creeping currents or the like can still occur. In both cases, therefore, a significant difference between the voltage at the low-voltage output 42 and the positive pole 34 of the battery 28 is measured and at the same time a decrease in the current flow at the low-voltage output 42 is observed. If this case occurs, then a control unit which receives and evaluates the measured values of the sensors can generate a corresponding signal for the driver of the motor vehicle, so that the latter is informed of the condition of his vehicle and can prompt maintenance as soon as possible. At the same time a corresponding error code is stored in a fault memory of the motor vehicle. This code can later be read out by the maintenance personnel by means of suitable diagnostic equipment, so that the necessary repairs can be carried out immediately.

Claims

PATENTANSPRÜCHE:  CLAIMS:
Verfahren zum Erkennen einer Verbindungsstörung zwischen einem Niedervoltausgang eines Spannungswandlers und einem Niedervoltbordnetz eines Kraftwagens, bei welchem eine Spannung am Niedervoltausgang des Spannungswandlers gegen Masse, eine Klemmenspannung einer Batterie des Niedervoltbordnetzes und ein Stromfluss am Niedervoltausgang des Spannungswandlers gemessen werden und eine Verbindungsstörung erkannt wird, wenn ein Absolutbetrag einer Differenz zwischen den gemessenen Spannungen einen ersten Schwellenwert überschreitet und gleichzeitig der Stromfluss am Niedervoltausgang einen zweiten Schwellenwert unterschreitet. A method for detecting a connection fault between a low-voltage output of a voltage converter and a low-voltage electrical system of a motor vehicle, in which a voltage at the low voltage output of the voltage converter to ground, a terminal voltage of a battery of the low-voltage vehicle electrical system and a current flow at the low-voltage output of the voltage converter are measured and a connection fault is detected when a Absolute amount of a difference between the measured voltages exceeds a first threshold and at the same time the current flow at the low-voltage output falls below a second threshold.
Verfahren nach Anspruch 1 , Method according to claim 1,
dadurch gekennzeichnet, dass characterized in that
der erste Schwellwert 1 ,5 V beträgt. the first threshold is 1.5V.
Verfahren nach Anspruch 1 oder 2, Method according to claim 1 or 2,
dadurch gekennzeichnet, dass characterized in that
der zweite Schwellwert 5 A beträgt. the second threshold is 5 amps.
Verfahren nach einem der Ansprüche 1 bis 3, Method according to one of claims 1 to 3,
dadurch gekennzeichnet, dass characterized in that
das Verfahren periodisch durchgeführt wird. the process is carried out periodically.
Verfahren nach Anspruch 4, Method according to claim 4,
dadurch gekennzeichnet, dass characterized in that
das Verfahren wenigstens einmal pro Millisekunde durchgeführt wird. the procedure is performed at least once every millisecond.
Verfahren nach einem der Ansprüche 1 bis 5, Method according to one of claims 1 to 5,
dadurch gekennzeichnet, dass characterized in that
beim Erkennen einer Verbindungsstörung ein Signal an einen Fahrer des Kraftwagens übermittelt wird. upon detection of a connection failure, a signal is transmitted to a driver of the motor vehicle.
Verfahren nach einem der Ansprüche 1 bis 6, Method according to one of claims 1 to 6,
dadurch gekennzeichnet, dass characterized in that
beim Erkennen einer Verbindungsstörung eine entsprechende Information in einem Fehlerspeicher des Kraftwagens abgelegt wird. upon detection of a connection fault, a corresponding information is stored in a fault memory of the motor vehicle.
PCT/EP2012/003542 2011-09-09 2012-08-21 Method for detecting a connection fault WO2013034249A2 (en)

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