DE202010010152U1 - Current measurement module - Google Patents

Abstract

Current measuring module (1) for measuring an electric current (I), in particular in a motor vehicle electrical system or in an electric drive, with
a) a current measuring resistor (R) through which the electric current to be measured (I) flows,
b) a measuring circuit (4) which is connected to the current measuring resistor (R) and measures the electrical voltage (U) which drops across the current measuring resistor (R),
c) an interface (5) which is connected to the measuring circuit (4) and outputs the electrical voltage (U) measured by the measuring circuit (4),
d) wherein the current measuring resistor (R), the measuring circuit (4) and the interface (5) are structurally integrated into the current measuring module (1),
marked by
e) a first separating element (6) between the measuring circuit (4) and the interface (5) for galvanic isolation of the interface (5) of the measuring circuit (4).

Description

The The invention relates to a current measuring module for measuring an electrical Electricity, in particular in a motor vehicle electrical system or in an electrical Drive.

Out EP 1 253 430 A1 and EP 1 030 185 A2 Current measuring modules are known, which can be used for example in a motor vehicle electrical system to measure the battery current. The current measurement is carried out according to the so-called four-wire technique by means of a low-impedance current measuring resistor, wherein the electrical current to be measured flows through the current measuring resistor, so that the voltage drop across the current measuring resistor according to Ohm's law is a measure of the electric current. As a current measuring resistor here an electron beam welded plate-shaped current measuring resistor can be used, as he, for example, in EP 0 605 800 A1 is described. The measurement of the voltage drop across the current measuring resistor is carried out in the known current measuring module by a measuring circuit, for example, as ASIC (Application Specific Integrated Circuit) according to EP 1 363 131 A1 can be executed. In addition, the known current measuring modules described above have an interface to output the measured voltage, wherein the interface can operate digitally and is integrated, for example, in the ASIC.

adversely At these known current measuring modules is the unsatisfactory performance.

Of the The invention is therefore based on the object, the known current measuring modules to improve accordingly.

These The object is achieved by an inventive current measuring module solved according to the main claim.

The Invention is based on the technical knowledge that the unsatisfactory Operating behavior of the known current measuring modules therefore stems that a galvanic connection between the interface on the one hand and the measuring circuit or the current measuring resistor on the other consists. The invention therefore comprises the general technical Teaching, the interface for the output of the above Current sense resistor falling voltage galvanic from the current sense resistor or disconnect from the measuring circuit.

The inventive current measuring module has - like also the conventional current measuring modules described at the beginning - one Current measuring resistor through, during operation of the electrical to be measured Electricity flows.

Of the Current measuring resistor is preferably low-resistance with an electrical Resistance of less than 1 mΩ, 500 μΩ, 200 μΩ, 100 μΩ, 50 μΩ or even less than 20 μΩ.

About that In addition, the current measuring resistor is preferably characterized a low linearity error of less than 100 ppm, 50 ppm, 20 ppm or even less than 10 ppm.

Farther has the current measurement module according to the invention preferably a low thermal resistance, which is preferably less than 1 K / W, 0.5 K / W, 0.2 K / W or even less than 0.1 K / W.

The current measuring resistor may be, for example, a plate-shaped current measuring resistor, as used in, for example, US Pat EP 0 605 800 A1 is described, so that the content of this patent application of the present description in the construction of the current sense resistor is fully attributable.

In the context of the invention, however, alternatively there is also the possibility that the current measuring resistor is a coaxial resistor, as it is known, for example, in US Pat WO 2007/068409 A1 is described, so that the content of this patent application of the present description in terms of the construction of the current sense resistor is fully attributable.

The However, the invention is in terms of the design of the current sense resistor not limited to the examples given above, but in principle also with other types of current measuring resistor realizable.

In addition, the current measuring module according to the invention-as well as the conventional current measuring modules described above-has a measuring circuit which is connected to the current measuring resistor and measures the electrical voltage which drops across the current measuring resistor. The measuring circuit can be realized for example as an ASIC, as for example in EP 1 363 131 A1 is described, so that the content of this patent application of the present description is fully attributable to the structure and operation of the measuring circuit. However, the invention is not limited to ASICs with regard to the structure and the mode of operation of the measuring circuit, but in principle can also be implemented with other analog and digital types of measuring circuits.

In addition, the current measuring module according to the invention also has an interface which is connected to the measuring circuit and outputs the voltage measured by the measuring circuit, the interface may be integrated, for example, in the serving as a measuring circuit ASIC. However, there is also the alternative possibility that the interface on the one hand and the measuring circuit on the other hand are separate components that are merely connected to each other.

The current measuring module according to the invention differs from conventional measuring arrangements in that the measuring circuit and the interface are structurally integrated into the current measuring module, as is the case with the known current measuring modules according to FIG EP 1 253 430 A1 and EP 1 030 185 A2 the case is.

The differs according to the invention current measurement module However, from these conventional current measuring modules through a first separator which is connected between the measuring circuit and the Interface is arranged and the interface is galvanic by the Measuring circuit disconnects.

In the preferred embodiment of the invention used as a separator, an optocoupler, the measuring circuit connects to the interface, with such optocouplers are known from the prior art and therefore not closer must be described.

It Alternatively, however, there is the possibility that as Separating element, a capacitive coupler or an inductive coupler is used, these types of separating elements also are known in the art and therefore not closer must be described.

The However, the invention is in terms of the concrete realization of Separator is not limited to the above examples. Rather, within the scope of the invention, other types be used by separating elements, which in itself from the state of the Technics are known.

Regarding the power supply of the current measuring module and in particular the measuring circuit and The interface in the current measurement module has various possibilities which are briefly described below.

In A variant of the invention provides an external power supply. which are connected to a power supply terminal of the current measuring module becomes. It is advantageous if the power supply a second Separating element having a galvanic isolation in the power supply between the measuring circuit and the interface on the other hand causes. This second separating element may be, for example, a DC-DC converter with galvanic isolation, such as a flyback converter or a flux converter, wherein Such DC-DC converter known from the prior art are and therefore do not need to be described in detail.

In In another variant of the invention, the power supply takes place the current measuring module, however, in part via the high-side connection of the Current measuring module. So the current measuring resistor is on its ground side (Low-side) and on its voltage side (high-side) with each connected to a power connector to the electrical to be measured To feed or derive electricity. To power the current measuring module exists in this variant of the invention, a connection between the live high-side connection on the one hand and the electronic components to be supplied (eg measuring circuit) the current measuring module on the other. The galvanic isolation between the measuring circuit on the one hand and the interface on the other is thus effected by the fact that the interface by the external power supply is supplied while the measuring circuit connected to the high-side connection.

In a third variant, however, a double flyback converter is provided which is powered by an external power supply and both the Measuring circuit as well as the interface powered, the double flyback converter a galvanic separation of these components causes.

In a preferred embodiment of the invention the current measuring module on a circuit board, wherein on the circuit board the measuring circuit, the interface, the first separator (z. B. Optocoupler) and possibly also the second separating element (eg., Flyback converter, Flow converter) are arranged so that the entire current measuring module forming a structural unit.

It is advantageous if the circuit board is mounted directly on the current measuring resistor, as for example in EP 1 253 430 A1 and EP 1 030 185 A2 is described, so that the content of these patent applications of the present description in terms of the circuit board assembly is fully attributable. In this case, the printed circuit board is preferably connected to the current measuring resistor by means of a solder connection, a welded connection or a press connection (eg pressfit).

The Connection (eg soldering) between the PCB and the current sense resistor is preferably not only mechanical, but also electrically.

Farther is to mention that the invention Current measuring module preferably comprises a sheath, which the measuring circuit, the interface, the first separator (z. B. Optocoupler) and possibly also the second separating element (eg., Flyback converter, Flux transducer) at least partially enveloped, wherein the envelope preferably made of plastic (eg, thermoset, thermoplastic, hot melt adhesive). The enclosure is preferably water and / or gas tight and can be used for electromagnetic shielding from an electrical conductive material.

Further is to be mentioned that the measuring circuit in the inventive Current measuring module preferably has a sampling rate of up to 300 kHz.

About that In addition, it is advantageous if the measuring circuit overcurrent detection having an automatic shutdown function, wherein the measurement circuit turns off when the measured voltage exceeds a certain limit.

Farther the measuring circuit can have a synchronization input in the context of the invention, to the measurement of falling over the current measuring resistor To synchronize tension. It is advantageous if the Synchronization with an adjustable delay time can be done with respect to the synchronization signal.

Further it is advantageous if the measuring circuit has an adjustable integration time having.

It has already been briefly mentioned above that the measuring circuit is preferably an integrated circuit, such as an ASIC according to FIG EP 1 363 131 A1 , However, there is also the possibility that the measuring circuit has an isolation converter, such as a one-bit isolation converter. In addition, there is also the possibility that the measuring circuit has a preamplifier, in particular a chopper amplifier.

at the interface of the current measuring module according to the invention it is preferably a digital interface, which outputs the measured voltage as a digital signal. It exists, however basically also the possibility that the interface works analogously.

The above described current measuring module according to the invention suitable for a variety of current measurement applications, such as the phase current measurement, the DC link measurement, the Measurement of a battery current of a high-voltage battery, in particular in a motor vehicle electrical system, or the measurement of a current of a Solar module or a wind turbine. However, the invention is not limited to the above-mentioned fields of application, but in principle also applicable in other areas.

Other advantageous developments of the invention are in the dependent claims marked or together with the description below of the preferred embodiments of the invention the figures explained in more detail.

It demonstrate:

1 1 is a schematic circuit diagram of a current measuring module according to the invention with a galvanic isolation;

2A a cross-sectional view of the current measuring module according to 1 .

2 B a view of the current measuring module according to 2A .

3 a schematic diagram of another embodiment of a current measuring module according to the invention,

4 a schematic diagram of another embodiment of a current measuring module according to the invention, as well as

5 a perspective view of the current measuring module according to the invention with a sheath made of plastic.

The 1 . 2A . 2 B and 5 show a first embodiment of a current measuring module according to the invention 1 , which can be used for example for current measurement in a motor vehicle electrical system or in an electric drive.

The actual current measurement takes place here in a conventional manner according to the known four-wire technology. For this purpose, the current measuring module has a low-impedance current measuring resistor R, which in this exemplary embodiment is a plate-shaped, electron-beam-welded resistor, as used, for example, in US Pat EP 0 605 800 A1 is described.

To initiate the current to be measured, the current measuring module has a high-side connection 2 on, while the derivative of the measured electric current I via a low-side connection 3 he follows.

The electric current I to be measured thus flows through the low-impedance current measuring resistor R, so that a voltage drop U across the Current measuring resistor R according to Ohm's law forms a measure of the electrical current I to be measured.

The voltage drop U across the current measuring resistor R is in this case by a measuring circuit 4 measured, the measuring circuit 4 realized in this embodiment as an ASIC. is, as it is for example in EP 1 363 131 A1 is described.

In addition, the current measuring module has an integrated interface 5 on, being the interface 5 outputs a digital signal corresponding to the voltage drop U across the current measuring resistor R.

Between the measuring circuit 4 and the interface 5 Here is an optocoupler 6 arranged, which is the interface 5 galvanic from the measuring circuit 4 separates. In other variants of the invention, however, instead of the optocoupler 6 Other types of galvanic isolators may be provided, such as capacitive couplers or inductive couplers.

The power supply of the current measuring module 1 via an external power supply connection 7 from an external power supply, not shown here, directly to the interface 5 connected is.

In addition, the external power supply connection 7 in the current measurement module 1 with a flyback converter 8th connected to the external power supply connection 7 galvanically isolated with the measuring circuit 4 connects and so does the power supply of the measuring circuit 4 ensures. The flyback converter 8th So make sure that not just the interface 5 and the measuring circuit 4 are galvanically isolated from each other, but also their power supplies. Instead of the flyback converter 8th However, other types of galvanic separation elements can be used.

From the cross-sectional view in 2A and from the supervision in 2 B is also apparent that the measuring circuit 4 , the optocoupler 6 , the interface 5 and the flyback converter 8th together on a circuit board 9 are arranged, wherein the circuit board 9 is mounted directly on the current measuring resistor R, such as in EP 1 030 185 A2 and EP 1 253 430 A1 is described.

Furthermore, it is off 5 seen that the entire current measurement module 1 in a plastic jacket 10 is arranged.

Finally shows 5 another plug contact 11 that on the one hand the power supply connection 7 and on the other hand a data bus 12 the interface 5 includes.

The embodiment according to 3 is largely consistent with the embodiment described above, so reference is made to avoid repetition of the above description, wherein the same reference numerals are used for corresponding details.

A special feature of this embodiment is the power supply of the current measuring module 1 that without the flyback converter 8th is working. Instead, this is in addition to the power supply connection 7 for the interface 5 another power supply connection 13 for the measuring circuit 4 intended. Here, too, is the power supply for the measuring circuit 4 galvanic of the power supply for the interface 5 separated.

4 Finally, shows a further modification of the embodiment according to 1 , wherein the flyback converter 8th is designed as a double flyback converter, which is both the interface 5 as well as the measuring circuit 4 supplied while causing a galvanic isolation.

The Invention is not limited to those described above Embodiments limited. Rather, it is a variety of variants and modifications possible, the also make use of the idea of the invention and therefore in fall within the scope of protection. In addition, the claimed Invention also protection for the subject of the dependent claims regardless of the features of the claims referred to.

1

Current measurement module

2

High-side connection

3

Low-side connection

4

measuring circuit

5

interface

6

optocoupler

7

Power connector

8th

flyback converter

9

circuit board

10

Plastic sheathing

11

plug contact

12

bus

13

Power connector

I

electrical electricity

R

Current sense resistor

U

Voltage drop over the current sense resistor

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 1253430 A1 [0002, 0016, 0026, 0053]
• - EP 1030185 A2 [0002, 0016, 0026, 0053]
• EP 0605800 A1 [0002, 0011, 0045]
• - EP 1363131 A1 [0002, 0014, 0033, 0048]
• WO 2007/068409 A1 [0012]

Claims (13)

Current measuring module ( 1 ) for measuring an electric current (I), in particular in a motor vehicle electrical system or in an electric drive, with a) a current measuring resistor (R) through which the electrical current (I) to be measured flows, b) a measuring circuit ( 4 ), which is connected to the current measuring resistor (R) and measures the electrical voltage (U) that drops across the current measuring resistor (R), c) an interface ( 5 ) connected to the measuring circuit ( 4 ) and that of the measuring circuit ( 4 ) outputs measured electrical voltage (U), d) wherein the current measuring resistor (R), the measuring circuit ( 4 ) and the interface ( 5 ) structurally into the current measuring module ( 1 ), characterized by e) a first separating element ( 6 ) between the measuring circuit ( 4 ) and the interface ( 5 ) for galvanic isolation of the interface ( 5 ) from the measuring circuit ( 4 ). Current measuring module ( 1 ) according to claim 1, characterized in that the first separating element ( 6 ) a) is an opto-coupler, the measuring circuit ( 4 ) with the interface ( 5 ) or b) is a capacitive coupler or c) is an inductive coupler. Current measuring module ( 1 ) according to one of the preceding claims, characterized by a power supply connection ( 7 ) to the external power supply of the measuring circuit ( 4 ), the interface ( 5 ) and / or the first separating element ( 6 ). Current measuring module ( 1 ) according to claim 3, characterized by a second separating element ( 8th ), which supplies the power supply of the measuring circuit ( 4 ) galvanically from the power supply of the interface ( 5 ) separates. Current measuring module ( 1 ) according to claim 4, characterized in that the second separating element ( 8th ) is a DC-DC converter with a galvanic isolation, in particular a flyback converter or a flux converter. Current measuring module ( 1 ) according to one of the preceding claims, characterized by a printed circuit board ( 9 ) on which the measuring circuit ( 4 ), the interface ( 5 ), the first separating element ( 6 ), and / or the second separating element ( 8th ) are arranged. Current measuring module ( 1 ) according to claim 6, characterized in that a) that the printed circuit board ( 9 ) is mounted directly on the current measuring resistor (R), and / or b) that the printed circuit board ( 9 ) is connected to the current measuring resistor (R) by a solder connection, a welded connection or a press connection, and / or c) that the solder connection also establishes an electrical connection between the circuit board ( 9 ) and the current measuring resistor (R). Current measuring module ( 1 ) according to one of the preceding claims, characterized by an envelope ( 10 ), which the measuring circuit ( 4 ), the interface ( 5 ), the first separating element ( 6 ) and / or the second separating element ( 8th ) at least partially enveloped. Current measuring module ( 1 ) according to claim 8, characterized in that the envelope ( 10 ) consists of plastic, in particular thermosetting plastic, thermoplastic or a hot melt adhesive. Current measuring module ( 1 ) according to one of the preceding claims, characterized in that a) that the measuring circuit ( 4 ) samples the voltage (U) across the current measuring resistor (R) at a specific sampling rate, the sampling rate being adjustable, and / or b) that the maximum sampling rate is greater than 20 kHz, 50 kHz, 100 kHz, 200 kHz, 250 kHz or 300 kHz, and / or c) that the measuring circuit ( 4 ) has an overcurrent detection with an automatic shutdown function, wherein the measuring circuit ( 4 ) turns off when the measured voltage (U) exceeds a certain limit, and / or d) that the measuring circuit ( 4 ) has a synchronization input in order to synchronize the measurement of the voltage (U) dropping across the current measuring resistor (R), and / or e) that the measuring circuit ( 4 ) carries out the measurement of the voltage (U) dropping across the current measuring resistor (R) with a specific delay time after a synchronization signal, the delay time being adjustable, and / or f) that the measuring circuit ( 4 ) has an adjustable integration time. Current measuring module ( 1 ) according to one of the preceding claims, characterized in that a) that the measuring circuit ( 4 ) comprises an integrated circuit, and / or b) that the measuring circuit ( 4 ) comprises an isolation converter, in particular a 1-bit isolation converter, and / or c) that the measurement circuit ( 4 ) Preamplifier, in particular a chopper amplifier has. Current measuring module ( 1 ) according to one of the preceding claims, characterized in that a) that the current measuring resistor (R) has two plate-shaped connecting parts ( 2 . 3 ) from a Leiterermateri al and a plate-shaped resistance element (R) made of a resistance alloy, wherein the resistance element (R) arranged electrically between the connection parts and the front side with the connecting parts ( 2 . 3 ) or b) that the current sense resistor (R) is a coaxial resistor. Current measuring module ( 1 ) according to one of the preceding claims, characterized in that the interface ( 5 ) a digital interface ( 5 ).