WO2023165658A1 - Dispositif de détection de court-circuit et système d'entraînement électrique - Google Patents

Dispositif de détection de court-circuit et système d'entraînement électrique Download PDF

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Publication number
WO2023165658A1
WO2023165658A1 PCT/DE2023/100167 DE2023100167W WO2023165658A1 WO 2023165658 A1 WO2023165658 A1 WO 2023165658A1 DE 2023100167 W DE2023100167 W DE 2023100167W WO 2023165658 A1 WO2023165658 A1 WO 2023165658A1
Authority
WO
WIPO (PCT)
Prior art keywords
short circuit
voltage
capacitor
detecting
value
Prior art date
Application number
PCT/DE2023/100167
Other languages
German (de)
English (en)
Inventor
Joachim Hemmer
Original Assignee
Schaeffler Technologies AG & Co. KG
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 Schaeffler Technologies AG & Co. KG filed Critical Schaeffler Technologies AG & Co. KG
Publication of WO2023165658A1 publication Critical patent/WO2023165658A1/fr

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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
    • G01R31/52—Testing for short-circuits, leakage current or ground faults
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
    • G01R19/16566—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533
    • G01R19/16576—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533 comparing DC or AC voltage with one threshold
    • 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

Definitions

  • the invention relates to a device for detecting a short circuit and an electric drive system which includes the device for detecting a short circuit.
  • electric drive units such as electric drive units of motor vehicles that can be driven by electric motors
  • power electronics for energizing and controlling the electric drive units.
  • Such power electronics are connected to a power electronic path.
  • the power electronics path usually includes a supply voltage interface on the control unit, an EMC filter, an inverter and an interface to the electric drive unit.
  • a current sensor is often installed in one of the two DC lines to detect such a short circuit.
  • the current sensor can detect a current with an unusually high amperage and thus detect a short circuit.
  • the integration of an EMC filter is necessary. However, this often means that due to the volume required by the EMC filter, only little space is available for arranging sensors.
  • the so-called common mode chokes included in the EMC filters have to be dimensioned very large, since their windings have to be designed for the high current.
  • EMC filters are not used in drive units in which only very little installation space is available.
  • a ferrite core or a core made of nanocrystalline material can be used.
  • such a core has to be wound around the line elements and accordingly also requires a large amount of installation space, which cannot always be made available.
  • Current sensors for short-circuit detection in the direct current path also take up a large amount of space, especially in the case of high currents, and thus compete with the EMC filter in terms of space.
  • the object of the present invention is to provide a device for detecting a short circuit and an electric drive system with which it is possible to detect an occurring short circuit in a simple, reliable, cost-effective and space-saving manner.
  • the invention relates to a device for detecting a short circuit in the power electronic direct current path of a control unit for an electric drive system.
  • This device comprises a capacitor between a positively polarized conducting element and a negatively polarized conducting element, and also comprises a detection device, with which, by comparing at least one value of a characteristic physical variable that changes when the voltage at the capacitor drops, with at least one reference value Statement regarding the existence of a short circuit between the positively polarized line and the negatively polarized line can be generated.
  • the device according to the invention for detecting a short circuit is correspondingly integrated in a direct current circuit.
  • the capacitor is electrically conductively connected to the positively poled conducting element and the negatively poled conducting element.
  • a respective guide element can be an electrical line or an electrical contact.
  • the device according to the invention for detecting a short circuit makes it possible to detect a short circuit between the conducting elements with little outlay in terms of equipment and correspondingly little installation space.
  • the physical variable can be the slope of the drop in voltage across the capacitor over time.
  • the angle of a tangent to a mathematical function that describes the drop in voltage across the capacitor over time at the time of detection is viewed as the slope here.
  • Uc(t) is the voltage across the capacitor as a function of time.
  • Uo is the voltage between the positively polarized conducting element and the negatively polarized conducting element.
  • t designates the course of time or the point in time at which the respective voltage Uc(t) is determined.
  • the capacitance of the capacitor Czk is known. Furthermore, a reference value of the slope of the drop in voltage across the capacitor is known, which was determined in a state of the electrical circuit in which it is known that there is no short circuit. In particular, this reference value can correspond to the maximum slope of the drop in voltage across the capacitor, ie in particular at the start of a voltage drop.
  • the detection device can be set up to measure the voltage and to derive the value of the physical quantity from it. Accordingly, it is provided for this embodiment that the voltage is measured and the slope of the drop in voltage derived from this measured value is compared with the reference value.
  • the reference value can be a calibration value of the physical quantity recorded before the comparison with the determined value of the physical quantity. If the physical quantity is the slope of the drop in voltage across the capacitor over time, then the reference value is correspondingly a reference slope.
  • the detection device can be set up to carry out the comparison of a value of the characteristic physical variable that changes when the voltage at the capacitor drops with a respective reference value at different defined points in time.
  • respective defined reference values can be assigned to the different defined points in time.
  • the respective slope between two measurement points can also be determined by linearly connecting these measurement points.
  • the slope of the voltage drop is determined in and/or between time measurement points, a decision can be made regarding the existence of a short circuit by comparing the number of situations in which the determined slope is greater than the reference slope with a previously specified limit number become.
  • the detection device can be set up to only carry out the comparison of a value of the physical variable with a reference value when the voltage across the capacitor has dropped to a value below a defined limit voltage across the capacitor.
  • the defined limit voltage can be 37% of the nominal voltage at the capacitor, for example.
  • the device according to the invention for detecting a short circuit makes it possible to carry out a method for quickly detecting a short circuit in the DC circuit of the power electronic path.
  • the detection of the short circuit is independent of whether direct current is provided to an electric drive motor for its operation, or whether the electric drive motor in generator mode converts mechanical energy into alternating current and this is in turn converted into direct current and made available by the inverter. In both cases, there is a DC voltage between the conducting elements between which the capacitor is arranged, so that the device according to the invention for detecting a short circuit can detect such a short circuit by detecting the voltage drop in the intermediate circuit.
  • a further aspect of the present invention is an electric drive system with a control device and at least one electric drive unit that can be controlled with the control device. Furthermore, the electric drive system comprises at least one device according to the invention for detecting a short circuit in the power electronic direct current path of the control device.
  • the electric drive system can have an inverter for converting the direct current provided by the control device into alternating current and alternating current for operating the electric drive unit.
  • the electric drive system is set up to drive an at least partially drivable motor vehicle. Short circuits can be detected both in engine operation and in generator operation or when recuperation is implemented.
  • the electric drive system can include a safety device which is set up to disconnect a current path between a voltage source and the electric drive unit when a short circuit is detected.
  • Other components of the electric drive system in the electronic power path can be a supply voltage interface on the control unit, an EMC filter and an electrical interface to an electric drive unit.
  • the electrical power can be up to 30 kW, for example up to 24 kW. With a 48 V supply of the electronic power path, this means currents of around 500 A. It is also possible to apply a voltage of 400 - 800 V at 500 A, and thus a power of up to 400 kW, e.g. B. in electric drives for sports vehicles.
  • the electric drive system can have the components mentioned without a current sensor on the DC side of the inverter. In this Embodiment, it makes sense to use three current sensors on the AC side of the inverter. This embodiment in particular makes it possible to integrate an adequately dimensioned EMC filter.
  • Figure 1 a possible structure of a device according to the invention
  • Figure 2 a diagram showing a typical voltage drop
  • FIG. 3 a diagram which shows a voltage drop in the device according to the invention for detecting a short circuit over a longer period of time
  • FIG. 4 a diagram which shows a voltage drop in the device according to the invention for detecting a short circuit over a shorter period of time.
  • FIG. 1 shows the power electronic architecture.
  • the device for detecting a short circuit or the electrical drive system comprises a control unit 1 which is connected to a supply voltage interface 3 by means of a positively polarized conducting element 4 and a negatively polarized conducting element 5 .
  • the two guide elements 4.5 form a direct current path 6.
  • a current sensor 7 in the negatively poled conducting element 5 which, however, does not necessarily have to be provided.
  • an EMC filter 8 is arranged in the direct current path 6 as part of the control unit 1 .
  • Figure 1 also indicates a short circuit 9 between the two guide elements 4.5.
  • a capacitor 10 is also located in the direct current path 6 .
  • a detection device 11 is assigned to the capacitor 10 and is able to detect a voltage drop across the capacitor 10 .
  • an inverter 12 is arranged in the control unit 1 for converting the direct current from the direct current path 6 into alternating current in order to then make this alternating current available to an electric drive unit 14 of the electric drive system via an electric interface 13 .
  • At least the capacitor 10 together with the detection device 11 forms the device for detecting a short circuit 2 .
  • a typical discharge curve has the course of a mathematical function 20, as is shown in FIG. 2 by way of example.
  • the mathematical function 20 is an e-function of the electrical voltage Uc over time t.
  • the capacitance of the capacitor Czk is decisive for determining the time constant Tau, as well as an equivalent existing resistance or the resistance at the capacitor R tot . If there is no short circuit 9, the resistance R tot is greater than a specific value. This value can be determined for control unit 1, for example, by a calibration process, for example by measuring the time constant Tau for various operating points.
  • This low resistance is connected in parallel with the previous resistance R ges and significantly reduces it, as a result of which the voltage across the capacitor 10 drops much faster than in situations in which there is no short circuit.
  • the drop in voltage or the slope of the drop in voltage is used to determine whether there is a short circuit.
  • a detected voltage drop or its increase is compared with a reference value that is characteristic of a situation in which there is no short circuit. If the gradient exceeds the reference value, a short circuit is detected in the system.
  • a command is generated from the detection of a short circuit, which command switches the control unit or the entire electric drive system to a safe state.
  • FIG. 3 shows the voltage across the capacitor 31 in a diagram. Within a period of 1 s, there is a sudden drop in system voltage or
  • FIG. 4 shows the region A identified in FIG. 3 in an enlarged view.
  • the capacitor first discharges slowly, namely between 1.0 s and 1.00005 s, and then discharges more quickly because of the switched-on short circuit. If one now compares the value of the intermediate circuit voltage with previously determined reference values, a very rapid drop is noticed and a short circuit is detected.
  • the respective slope of the mathematical function 20 representing the voltage across the capacitor 31 is to be determined at defined points in time.
  • the slope here corresponds to the angle 22 between a tangent 21 applied to the mathematical function 20 and the abscissa of the coordinate system or the t-axis.
  • more than two points in time should be used to determine the slope in order to exclude or reduce measurement errors.
  • a high sampling rate is particularly recommended for systems with a PWM frequency of up to 20 kHz.
  • a higher PWM frequency e.g. B.
  • the presented method and the device according to the invention is also suitable, since faster scanning is possible there.
  • the device according to the invention is suitable for power electronics with a large capacitor capacity, since the voltage drops very slowly here and correspondingly many measuring points can be recorded in order to carry out an evaluation.
  • the current sensor shown in FIG. 1 is not absolutely necessary in the embodiment shown here.
  • the device according to the invention for detecting a short circuit or the electric drive system according to the invention can also do without such a current sensor 7 instead.
  • the arrangement of the current sensor 7 is recommended for systems with a high safety level, such as for example for autonomous driving, in order to implement a second short-circuit monitoring using the current sensor 7 .

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)

Abstract

L'invention concerne un dispositif de détection de court-circuit et un système d'entraînement électrique qui comprend le dispositif de détection de court-circuit. Le dispositif (2) de détection de court-circuit dans le circuit de courant continu (6) de l'électronique de puissance d'un dispositif de commande (1) pour un système d'entraînement électrique comprend un condensateur (10) entre un élément conducteur à pôle positif (4) et un élément conducteur à pôle négatif (5), et comprend également un dispositif de détection (11) avec lequel, en comparant au moins une valeur d'une variable physique caractéristique, qui change si la tension au condensateur (31) chute, avec au moins une valeur de référence, il est possible de générer un énoncé sur la présence d'un court-circuit (9) entre un élément conducteur à pôle positif (4) et un élément conducteur à pôle négatif (5) Le dispositif de détection de court-circuit de l'invention et le système d'entraînement électrique permettent de détecter tout court-circuit de manière simple, sûre, peu coûteuse et peu encombrante.
PCT/DE2023/100167 2022-03-04 2023-03-02 Dispositif de détection de court-circuit et système d'entraînement électrique WO2023165658A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102022105180.3A DE102022105180A1 (de) 2022-03-04 2022-03-04 Einrichtung zur Erkennung eines Kurzschlusses und elektrisches Antriebssystem
DE102022105180.3 2022-03-04

Publications (1)

Publication Number Publication Date
WO2023165658A1 true WO2023165658A1 (fr) 2023-09-07

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DE (1) DE102022105180A1 (fr)
WO (1) WO2023165658A1 (fr)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2009791A1 (fr) * 2007-06-29 2008-12-31 Fujitsu Ten Limited Appareil de protection électrique et unité de contrôle électronique
JP2010041794A (ja) * 2008-08-04 2010-02-18 Nissan Motor Co Ltd 車両駆動装置
DE102010042750A1 (de) * 2010-10-21 2012-04-26 Siemens Aktiengesellschaft Verfahren und Vorrichtung zum Erkennen eines Kurzschlusses
US20130297237A1 (en) * 2012-05-01 2013-11-07 Caterpillar Inc. Systems and Methods for Detecting Ultracapacitor Cell Short Circuits

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2009791A1 (fr) * 2007-06-29 2008-12-31 Fujitsu Ten Limited Appareil de protection électrique et unité de contrôle électronique
JP2010041794A (ja) * 2008-08-04 2010-02-18 Nissan Motor Co Ltd 車両駆動装置
DE102010042750A1 (de) * 2010-10-21 2012-04-26 Siemens Aktiengesellschaft Verfahren und Vorrichtung zum Erkennen eines Kurzschlusses
US20130297237A1 (en) * 2012-05-01 2013-11-07 Caterpillar Inc. Systems and Methods for Detecting Ultracapacitor Cell Short Circuits

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