DE102017214408A1 - Device for determining an insulation resistance, battery management system, automobile, portable measuring unit and method for insulation resistance determination. - Google Patents

Abstract

Device (2) for determining an insulation resistance (R, R) comprising: - a first series circuit (6a) having a first series resistor (R) and a first leak detection switch (S), the first series circuit (6a) being arranged, a first connection node (16a) between the first series circuit (6a) and a first electrical conductor (15a) to connect to a ground (4); and - a second series circuit (6b) having a second series resistor (R) and a second leak detection switch (S), wherein the second series circuit (6b) is arranged, a second connection node (16b) between the second series circuit (6b) and a second electrical Conductor (15b) to connect to the ground (4); characterized in that the first and second series circuits (6a, 6b) have a common connection node (17) with a common sense resistor (R) through which they are connected to ground (4).

Description

The invention relates to an apparatus for determining an insulation resistance, a battery management system, an automobile, a portable measurement unit and a method for insulation resistance determination.

Insulation resistance measurements must be performed on new installations, conversions, modifications, repairs, electric vehicles for road traffic and in cases of failure. With low insulation resistance in traction batteries of electric vehicles, which are measured during the main investigation, threatens the loss of the general operating permit and thus the insurance protection. Furthermore, too low insulation resistance represents immense safety risks. Accordingly, high demands are placed on insulation resistance measuring systems.

In general, AC-based methods for determining an insulation resistance are known. However, in these methods, the insulation resistances of a negative and a positive pole of a voltage source can not be distinguished from each other.

DE 10 2008 047 398 A1 discloses the determination of an insulation resistance of a traction battery by means of a parallel arrangement of two series circuits, each containing a switch, a series resistor and a measuring resistor. In addition, isolation monitors are known with star point switching. Overall, however, these solutions have the disadvantage in common that they are expensive and space consuming. In addition, such arrangements are more susceptible to error due to their complexity.

DE 103 04 234 A1 discloses a series circuit of two series resistors and two measuring resistors, which is connected to the electrical system ground, for the determination of insulation resistance of a traction battery. In this case, the voltage dropping across it for the calculation of the insulation resistances can be determined at both measuring resistors. The series circuit is connected at several connection nodes with a measuring unit. In this case, however, a quiescent current flows through the series connection, which reduces the energy efficiency. Furthermore, two measuring resistors are necessary, which increases the cost of this circuit. In addition, the measurement error increases due to the series arrangement of the two measuring resistors. In addition, a complex connected measuring unit is necessary.

Based on the aforementioned prior art, it is therefore an object of the present invention to provide a device which allows a simplified, less expensive and less error-prone determination of an insulation resistance. A further object of the present invention is to provide a battery management system, an automobile, a portable measuring unit and a method for measuring an insulation resistance, by means of which the stated advantages can likewise be realized.

Disclosure of the invention

The aforementioned object is achieved by the features of claim 1. According to a first aspect, the present invention relates to a device for determining an insulation resistance. The term "insulation resistance" is understood in the context of the present invention, the resistance between an electrical conductor and the ground (or ground, chassis ground (GND)). The respective insulation resistance is not an electrical component but a detected insulation fault. Since there is no ideal insulator, each insulation also has an ohmic resistance whose value can be very high, but still always finite. The insulation resistance may, for example, depending on the insulation quality of the electrical conductor, in a range between 1 Ω to 5000 MΩ.

The inventive device comprises a first series circuit having a first series resistor and a first leak detection switch, wherein the first series circuit is arranged to connect a first connection node between the first series circuit and a first electrical conductor to a ground. For example, the earth may be the ground potential of a vehicle electrical system. The first leak detection switch has the task of closing the first series connection. As a leak detection switch, for example, a relay and / or a contactor and / or a field effect transistor (FET) and / or an opto-MOS come into question. If e.g. the first leak detection switch is opened, no electric current flows through the first series connection. Thus, the problem of a quiescent current in the device according to the invention can be avoided. This has the advantage of reducing the energy consumption and thus the cost and complexity of the device. As the first electrical conductor, for example, the positive pole of a traction board network comes into question.

Furthermore, the device according to the invention comprises a second series circuit with a second series resistor and a second leak detection switch, wherein the second series circuit is arranged to connect a second connection node between the second series circuit and a second electrical conductor to the ground. By the first and second series circuits (when a respective leak detection switch is closed), the electrical conductors and the earth are no longer galvanically isolated from each other. As it were, an artificial insulation fault is generated. The first and second series resistors may therefore be correspondingly high-impedance and have, for example, 0.1 to 100 MΩ, preferably 1 to 50 MΩ, particularly preferably 1 to 10 MΩ.

The second series circuit is configured analogously to the first series circuit. Here, the first and the second series circuit have a common connection node with a first terminal of a common measuring resistor, via which they are connected to the ground. This arrangement can also be referred to as a "Y-arrangement" based on the representation of the two series circuits and the common measuring resistor in a circuit diagram. This arrangement is space-efficient, in contrast to the known solutions. Thus, costs can be saved in terms of components and space requirements of the circuit. Furthermore, the complexity of the circuit and thus also the susceptibility to interference or the probability of failure and the occurrence of measurement errors in the determination of the insulation resistances can be reduced by the simplicity of the "Y-arrangement" according to the invention. In addition, fewer connections to a possible evaluation are needed. For example, only a single evaluation unit can be provided for the device according to the invention.

At the common measuring resistor, for example, a measuring voltage dropping at this with respect to the first electrical conductor can be tapped. This is possible, for example, by a voltage measuring device, which may be located in particular in an evaluation unit. If, for example, the measuring voltage at the common measuring resistor is tapped off, the first leak detection switch is closed and the second leak detection switch is opened. Conversely, it behaves, for example, in the determination of the measuring voltage and the second insulation resistance. The respective measurement voltage can be used to determine a first and / or second insulation resistance.

Thus, the device according to the invention is less expensive, less prone to interference and measurement errors and space-saving and energy efficient. Furthermore, the device according to the invention can be used to determine an insulation resistance in all known high-voltage components, in particular in electrical industrial installations, in high-voltage batteries or in high-voltage lines. For example, the insulation resistances of a traction board network, in particular a high-voltage battery, a means of locomotion with the device according to the invention can be easily determined. As a means of transport within the meaning of the device are, for example, automobiles, especially cars and / or trucks, aircraft, ships and / or motorcycles in question.

The dependent claims have advantageous developments to the content.

According to an advantageous embodiment of the device according to the invention, the first electrical conductor is at the potential of the positive pole of a traction board network, in particular a high-voltage battery. Thus, by closing a first leak detection switch in a simple manner, the insulation resistance between a positive pole of a traction board network and an electrical ground potential can be determined. Since the second electrical conductor can be at the potential of the negative pole of the traction power supply, in particular the high-voltage battery, a need-based switching between the positive and negative poles is possible by the first and second leak detection switch, if both insulation resistances, for example, must be determined sequentially. The switching can be done for example by an evaluation and / or a switching unit. The inventive arrangement a space- and material-saving design and also a reliable and trouble-free determination of the first and / or the second insulation resistance is possible.

In an advantageous development of the device according to the invention, the first series circuit is arranged to connect a positive conductor of a voltage source to the ground. Thus, by closing the first leak detection switch (while the second one is open), the first isolation resistance of the positive conductor to the ground can be selectively determined independently of the connectivity of the second series connection. In this case, the second series connection can either be at the negative conductor of the same voltage source or at an electrical conductor of an entirely different voltage source in a complex electrical network. Such a network may preferably be a traction board network of a means of transportation.

In another advantageous embodiment of the present invention, the first and / or the second leak detection switch comprises a relay and / or a contactor and / or a FET and / or an opto-MOS. Thus, the leak detection switch can be easily controlled and depending on the circuit design, eg with respect to high currents is a contactor advantageous to represent a reliable interruption of the quiescent current and allow reliable, if necessary, a determination of the first and / or second insulation resistance.

Furthermore, within an advantageous development, the device according to the invention can have a voltage measuring device arranged on the measuring resistor. Preferably, the voltage measuring device has an analog-to-digital converter, by means of which the measured voltage is provided for a further arbitrary digital evaluation. Since only the common measuring resistor is connected to the voltage measuring device, further components, such as copper wires, can be saved.

According to a further advantageous embodiment, the device according to the invention is connected to an evaluation unit. The evaluation unit can in particular comprise an electrical regulator and / or a digital display and / or a microcontroller and / or an electronic control unit and / or a fuse unit, for example for outputting a warning signal if the insulation resistances are too low, and / or a processor. Furthermore, the evaluation unit is set up to control the first and / or the second leak detection switch and / or to measure the measurement voltage by means of the voltage measuring device on the measuring resistor. The evaluation unit may preferably also be part of another electrical circuit. Thus, the device according to the invention has a high degree of variability with regard to an evaluation unit for determining the insulation resistance. Furthermore, the first and / or the second insulation resistance can be read out via the evaluation unit via an external device. The evaluation unit can be connected, for example, to an on-board diagnostic unit of a means of locomotion. In this case, the evaluation unit, for example, pass on a time profile of an insulation resistance and / or an error message to an on-board diagnostic unit. Furthermore, in the event of a security risk existing, for example, to an end user, the evaluation unit may interrupt the power connection after a predefined period of time and / or announce the interruption to the end user and / or merely output an error message to the end user.

wobei

• R₁ der erste Vorwiderstand;
• R₂ der zweite Vorwiderstand;
• R_P ein erster Isolationswiderstand;
• R_N ein zweiter Isolationswiderstand;
• R_M der gemeinsame Messwiderstand;
• U_B die Spannung zwischen dem ersten und dem zweiten Verbindungsknoten;
• und U_M eine über R_M abfallende Spannung ist.

In a preferred embodiment, the evaluation unit is set up to calculate the first and / or second insulation resistance according to one of the following formulas (a) or (b): $$\left(\text{a}\right)R_P=\frac{U_B\cdot R_M}{U_M}-\left({\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="DE102017214408A1\_0005.png"\; state="\{\{state\}\}">R</figure-callout>}}_1+R_M\right)\text{or}\left(\text{b}\right)R_N=\frac{U_B\cdot R_M}{U_M}-\left({\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="DE102017214408A1\_0006.png"\; state="\{\{state\}\}">R</figure-callout>}}_2+R_M\right)$$

in which

• R _{1 is} the first series resistor;
• R _{2 is} the second series resistor;
• R _{P is} a first insulation resistance;
• R _{N is} a second insulation resistance;
• R _{M is} the common measuring resistor;
• U _{B is} the voltage between the first and second connection nodes;
• and U _M one over R _M falling voltage is.

Here are R ₁ . R ₂ . R _M and U _B predefined by the components of the electrical circuit. The common resistance R _M (eg R _M <10kΩ, U _M <5V) decreasing voltage U _M can in particular be measured with a measuring device which has an analog-to-digital converter which is integrated in the evaluation unit. By the analog-to-digital converter, this measurement is digitized and the evaluation unit can, for example, easily calculate the first and / or the second insulation resistance, depending on the closed leak detection switch.

The following aspects of the invention include the advantageous embodiments and further developments as well as the general advantages of the device according to the invention and the technical effects associated therewith.

According to a second aspect, the present invention relates to a battery management system comprising a device according to the invention according to the first aspect. By using a device according to the invention cost optimization of a battery management system can be made.

According to a third aspect, the present invention relates to a
An automobile comprising a high-voltage battery with an integrated device for determining an insulation resistance according to the first aspect of the present invention and / or a battery management system according to the second aspect of the present invention. Due to the simplicity, the small footprint and the lower cost can be provided as a safety determination system for insulation resistance in a high-voltage vehicle electrical system and / or a high-voltage battery for an automobile.

According to a fourth aspect, the present invention relates to a portable measuring unit for determining an insulation resistance comprising the device according to the invention. This results in the advantages of the inventive device according to the first aspect for the insulation resistance determination of many different electrical conductors of different circuits in a fast and efficient manner. Here, for example, the first and / or the second series circuit of the device according to the invention are adapted to be connected via terminals or other releasable and conductive fastening devices with the electrical conductors at a first / and or second connection node. For example, a portable measuring unit may comprise a hand-held device, for example an insulation measuring device and / or a multimeter, comprising the device according to the invention for checking electronic systems and / or machines.

According to a fifth aspect, the present invention relates to a method for insulation resistance measurement by means of a device according to the first aspect.

The method includes closing a first leak detection switch and opening a second leak detection switch when a first insulation resistance is to be determined via a first series connection. For the determination of a second insulation resistance via a second series connection, the first leak detection switch is opened and the second leak detection switch is closed. Subsequently, depending on the leak detection switch arrangement, a measurement is carried out via a common measuring resistor R _M declining voltage U _M , This is done, for example, via an evaluation, determining a first or a second insulation resistance R _P respectively. R _N via the formula (a) or (b).

list of figures

• 1 ein Fortbewegungsmittel mit der erfindungsgemäßen Vorrichtung im Traktionsbordnetz;
• 2 ein Schaltbild der erfindungsgemäßen Vorrichtung zur Bestimmung des Isolationswiderstandes; und
• 3 ein Flussdiagramm eines Ausführungsbeispiels des erfindungsgemäßen Verfahrens.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings:

• 1 a means of transport with the device according to the invention in the traction board network;
• 2 a circuit diagram of the device according to the invention for determining the insulation resistance; and
• 3 a flowchart of an embodiment of the method according to the invention.

1 shows a means of transportation 1 in the form of an automobile in which the device according to the invention 2 for determining an insulation resistance R _P . R _N with a traction board network 3 in the form of a high-voltage battery 10 (in 2 shown), the means of transport 1 connected is. Here is the first series connection 6a with the positive pole (not shown) of a traction board network 3 connected. Furthermore, the second series circuit 6b with the negative pole (not shown) of the traction board network 3 connected. The two series connections 6a . 6b are about the common resistance R _M with the earth 4 connected. Furthermore, the device 2 for determining an insulation resistance R _P . R _N with an evaluation unit 7 which in particular includes a voltage measuring device (not shown) which is set up, a voltage at the common resistance R _M to eat. The evaluation unit 7 is still with a memory 5 and an on-board diagnostic device 8th connected. The memory 5 and / or the on-board diagnostic device may serve to provide a measurement protocol of insulation resistance R _P . R _N Record and / or error messages for example, too high insulation resistance R _P . R _N to log.

2 shows an electrical circuit diagram of the device according to the invention 2 for determining an insulation resistance R _P . R _N , The first series connection 6a includes a first leak detection switch S ₁ and a first series resistor R ₁ while the second series connection 6b a second Leak detection switch S ₂ and a second series resistor R ₂ includes. The first series connection 6a is with the potential of a plus pole 15a a high-voltage battery 10 via a first connection node 16a and the second series circuit 6b with the potential of a negative pole 15b the high-voltage battery 10 via a second connection node 16b connected with the earth 4 connected. Both series connections 6a . 6b are about a common resistance R _M at a common connection node 17 with the earth 4 connected. This arrangement is also referred to as "Y-arrangement". At this resistance R _M can the voltage drop U _M by means of a voltage measuring device 14 be measured. Depending on whether the first leak detection switch S ₁ or the second leak detection switch S ₂ open or closed, may be out of tension U _M via an evaluation unit 7 from the measured voltage U _M according to formula (a) or (b) the first insulation resistance between the positive pole R _P or the second insulation resistance between the negative pole R _N and the earth 4 be determined. The measured voltage may be via an analog-to-digital converter (not shown) in the voltmeter 14 to an evaluation unit 7 be passed on. In simple terms, the first leak detection switch S ₁ closed and the second leak detection switch S ₂ be open to a determination of the first insulation resistance R _P to enable. In the reverse switching state of the leak detection switch S ₁ . S ₂ can the second insulation resistance R _N be determined. It should be noted again that it is R _P and R _N not real components (analogous to internal resistance). These fictitious "components" are merely drawn for a simplified understanding.

3 shows a flowchart of the method according to the invention. The first step 100 of the method according to the invention depends on which insulation resistance R _P . R _N should be determined. For determining the first insulation resistance R _P a closing occurs 100a of the first leak detection switch S ₁ and opening the second leak detection switch S ₂ , Alternatively, to determine the second insulation resistance R _N lock in 100b of the second leak detection switch S ₂ and opening the first leak detection switch S ₁ , In a second step 200 the measurement takes place via a common measuring resistor R _M declining voltage U _M with respect to the closed first or second series connection. The third step 300 depends again on the position of the first and second leak detection switch S ₁ . S ₂ from. In a third step 300a a determination is made of the first insulation resistance R _P according to formula (a), when the first leak detection switch S ₁ was closed and the second leak detection switch S ₂ In the first step 100a was opened. In an alternative third step 300b a determination is made of the first insulation resistance R _N according to formula (b), when the first leak detection switch S ₁ opened and the second leak detection switch S ₂ In the first step 100b has been closed.

LIST OF REFERENCE NUMBERS

1

Means

2

Device for determining an insulation resistance

3

Traction vehicle electrical system

4

Earth / vehicle mass

5

Storage

6a

first series connection

6b

second series connection

7

evaluation

8th

On-board diagnostic device

10

High-voltage battery

14

voltmeter

17

common connection node

15a

first electrical conductor

15b

second electrical conductor

16a

first connection node

16b

second connection node

100a-300b

steps

R ₁

first resistor

R ₂

second series resistor

R _M

common measuring resistor

R _N

second insulation resistance

R _P

first insulation resistance

S ₁

first leak detection switch

S ₂

second leak detection switch

U _B

Voltage between the first and second connection nodes

U _M

Tension that over R _M drops (measuring voltage)

(from)

Formula for calculating an insulation resistance

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008047398 A1 [0004]
• DE 10304234 A1 [0005]

Claims (12)

Device (2) for determining an insulation resistance (R _N , R _P ) comprising: - a first series circuit (6a) having a first series resistor (R ₁ ) and a first leak detection switch (S ₁ ), the first series circuit (6a) being arranged connecting a first connection node (16a) between the first series circuit (6a) and a first electrical conductor (15a) to a ground (4); and - a second series circuit (6b) having a second series resistor (R ₂ ) and a second leak detection switch (S ₂ ), wherein the second series circuit (6b) is arranged, a second connection node (16b) between the second series circuit (6b) and one second electrical conductor (15b) to connect to the ground (4); characterized in that the first and the second series circuit (6a, 6b) have a common connection node (17) with a common measuring resistor (R _M ), via which they are connected to the ground (4). Device (2) according to Claim 1 , wherein the first electrical conductor (15a) is the positive pole of a traction board network (3), in particular a high-voltage battery (10), and / or the second electrical conductor (15b) is the negative pole of a traction board network (3), in particular of the high-voltage battery (10 ) is. Device (2) according to Claim 1 or 2 wherein the first series circuit (6a) is arranged to connect a potential of a positive pole of a voltage source to the potential of the ground (4) and / or the second series circuit (6b) is arranged, a potential of a negative pole of the voltage source to the potential to connect the earth (4) or electrical conductors (15a, 15b) of different voltage sources to the ground (4) to connect. Device (2) according to one of the preceding claims, wherein the first and / or the second leak detection switch (S ₁ , S ₂ ) comprises a relay and / or a contactor and / or a FET and / or an opto-MOS. Device (2) according to one of the preceding claims, further comprising a voltage measuring device (14) which is in particular adapted to measure a measuring voltage (U _M ) on the common measuring resistor (R _M ), wherein the voltage measuring device (14) in particular an analog-digital Transducer has. Device (2) according to one of the preceding claims, wherein the device (2) is connected to an evaluation unit (7) which is set up to control the first and / or the second leak detection switch (S ₁ , S ₂ ), in each case exclusively to close and / or to measure the measuring voltage (U _M ) using the voltmeter (7) on the measuring resistor (R _M ). Device (2) according to Claim 6 , wherein the evaluation unit (7) is set up to calculate the first and / or the second insulation resistance (R _N , R _P ) according to one of the following formulas (a) or (b): $$\left(\text{a}\right)R_P=\frac{U_B\cdot R_M}{U_M}-\left(R_1+R_M\right)\text{or}\left(\text{b}\right)R_N=\frac{U_B\cdot R_M}{U_M}-\left(R_2+R_M\right)$$

where R _{1 is} the first series resistor, R _{2 is} the second series resistor, R _{P is} the first insulation resistor; R _{N is} the second insulation resistance; R _{M is} the common measuring resistor; U _{B is} the voltage between the first and second Verbindungsungskoten (16 a, 16 b) and U _{M is} a voltage drop across R _M. Battery management system comprising a device (2) for determining an insulation resistance (R _N , R _P ) according to one of Claims 1 to 7 , Automotive comprising a high-voltage battery (10) with an integrated device (2) for determining an insulation resistance (R _N , R _P ) according to one of Claims 1 to 7 and / or a battery management system Claim 8 , Portable measuring unit comprising a device (2) for determining an insulation resistance (R _N , R _P ) according to one of Claims 1 to 7 , Method for insulation resistance determination by means of a device (2) according to one of the Claims 1 to 7 full: - Closing (100a) the first leak detection switch (S ₁ ) and opening the second leak detection switch (S ₂ ); - measuring (200) a voltage drop across a common measuring resistor (R _M ) (U _M ); and determining (300a) a first insulation resistance (R _P ) via formula (a): $$R_P=\frac{U_B\cdot R_M}{U_M}-\left(R_1+R_M\right).$$

where R _{1 is} the first series resistor, R _{P is} the first insulation resistance; R _{M is} the common measuring resistor; U _{B is} the voltage between the first and second Verbindungsungskoten (16 a, 16 b) and U _{M is} a voltage drop across R _M. Method for insulation resistance determination by means of a device (2) according to one of the Claims 1 to 7 comprising: - closing (100b) the second leak detection switch (S ₂ ) and opening the first leak detection switch (S ₁ ); - measuring (200) a voltage drop across a common measuring resistor (R _M ) (U _M ); and determining (300b) a second insulation resistance (R _N ) via formula (b): $$R_N=\frac{U_B\cdot R_M}{U_M}-\left(R_2+R_M\right)$$

where R _{2 is} the second series resistor, R _{N is} the second insulation resistance; R _{M is} the common measuring resistor; U _{B is} the voltage between the first and second Verbindungsungskoten (16 a, 16 b) and U _{M is} a voltage drop across R _M.

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