WO2023138935A1

WO2023138935A1 - Current sensor module for an electrical energy store

Info

Publication number: WO2023138935A1
Application number: PCT/EP2023/050317
Authority: WO
Inventors: Robert Peter Uhlig
Original assignee: Robert Bosch Gmbh
Priority date: 2022-01-20
Filing date: 2023-01-09
Publication date: 2023-07-27
Also published as: DE102022200645A1

Abstract

The invention relates to a current sensor module (100) for an electrical energy store, comprising: - at least one first sensor (10) having two sensor elements (1a, 1b), a first sensor element (1a) of the first sensor (1) being of a first magnetic field measurement technology, and a second sensor element (1b) of the first sensor (1) being of a second magnetic field measurement technology; - at least one second sensor (2) having two sensor elements (2a, 2b), a first sensor element (2a) of the second sensor (2) being of a first magnetic field measurement technology, and a second sensor element (2b) of the second sensor (2) being of a second magnetic field measurement technology, wherein sensing directions of the first and of the second sensor elements (1a, 1b, 2a, 2b) are arranged so as to be normal with respect to one another; - a printed circuit board (3) on which the two sensors (1, 2) are arranged so as to be galvanically conductive; and - an evaluation device (4) by means of which measured values of the two sensors (1, 2) can be evaluated separately from one another, wherein indirect measurement of the current can be performed using magnetic field measurements of the two sensors (1, 2), wherein the printed circuit board (3) can be attached to a bus bar (200) of the electrical energy store such that, when the current sensor module (100) is in the intended attachment position on the bus bar (200) of the electrical energy store, one sensor (1, 2) is arranged in each edge portion of the bus bar.

Description

title

Current sensor module for an electric

The invention relates to a current sensor module for an electrical energy store. The invention also relates to a method for operating a current sensor module for an electrical energy store.

State of the art

With increasing electrification, current measurement in the vehicle is becoming increasingly important, with several different measurement methods being known for this purpose. A classic approach uses a measuring shunt, for example, to measure an electrical current flowing across a suitable conductor section based on an electrical voltage drop.

Also known are non-contact systems that use the magnetic field, for example, to evaluate the current flowing as the cause of the field, with different approaches being known for non-contact current measurement. AMR, GMR and, more recently, TMR sensors (anisotropic MR effect, giant magneto-resistance, tunneling magneto-resistance) are primarily used for non-contact current measurement. The sensors mentioned are mostly used in measuring bridge arrangements for linear applications.

Disclosure of Invention

It is an object of the present invention to provide an improved device for measuring electrical current of an electrical energy storage device.

The object is achieved according to a first aspect with a current sensor module for an electrical energy store, having: - At least one first sensor having two sensor elements, wherein a first sensor element of the first sensor is embodied in a first magnetic field measurement technology and a second sensor element of the first sensor is embodied in a second magnetic field measurement technology;

- At least one second sensor having two sensor elements, wherein a first sensor element of the second sensor is formed in a first magnetic field measurement technology and a second sensor element of the second sensor is formed in a second magnetic field measurement technology, wherein sensing directions of the first and second sensor elements are arranged perpendicular to one another;

- A printed circuit board on which the two sensors are arranged in a galvanically conductive manner; and

- an evaluation device with which the measured values of the two sensors can be evaluated separately from one another, in which case an indirect measurement of the current can be carried out from magnetic field measurements of the two sensors, the printed circuit board being able to be attached to a busbar (200) of the electrical energy storage device in such a way that, when the current sensor module is installed as intended on the busbar of the electrical energy storage device, one sensor is arranged in each case in an edge section of the busbar.

In this way, a current sensor module is provided with which an electric current flowing in the busbar can be measured between the electrical energy store (e.g. battery) and a further element (e.g. inverter). In this way, a magnetic field measurement is made possible in up to three spatial directions. Based on the direct current measurement, a precise statement can be made about the state of charge of the battery. Advantageously, the magnetic field sensors with their sensor elements implemented in different sensing technologies can cover high dynamics, whereby, for example, an emergency shutdown and a high-precision current measurement can be implemented. As a result, an indirect measurement of the electric current in the conductor is carried out with the two sensors.

According to a second aspect, the object is achieved with a method for operating a current sensor module for an electrical energy store, having the steps: - determining a magnetic field with a first sensor with a first sensor element of a first magnetic field measurement technology;

- determining a magnetic field with a second sensor with a first sensor element of the first or a second magnetic field measurement technology, the measurements of both sensors being evaluated separately from one another; and

- Determining a current flow for an electrical energy store from the determined magnetic fields.

Preferred embodiments of the current sensor module are subject of dependent claims.

A preferred development of the current sensor module is characterized in that it also has a plug connector arranged on the printed circuit board for connecting the current sensor module to a superordinate module.

A further preferred development of the current sensor module is characterized in that the first magnetic field measurement technology of a first sensor element is one of the following: TMR, AMR, GMR. With this technology (also called xMR technology), a magnetic field can advantageously be measured in-plane, i.e. within the plane of the current conduction. In this case, TMR advantageously has very low noise and can therefore be used for a magnetic field measurement with high resolution.

A further preferred development of the current sensor module provides that the second magnetic field measurement technology of the second sensor element is based on the Hall effect, in particular using graphs. Alternatively, other so-called 2D materials can also be considered for use. 2D materials are materials that mainly expand in one plane and only expand a few atomic layers perpendicular to it. Due to the desired position relative to the current-carrying conductor, the sensor element with this technology has a low-pass character, ie rapid changes in the current do not have as strong an effect on the sensor signal as slow changes. This technology is used to measure magnetic fields out-of-plane, ie from the plane of the power supply. Another preferred embodiment of the current sensor module is characterized in that a sensor signal of the first sensor element of a first and a second sensor can be evaluated against a first threshold value of an amplitude of the magnetic field component, which is related to the electric current actually flowing in the busbar.

A further preferred embodiment of the current sensor is characterized in that the current sensor module also has at least one shielding element against an external electromagnetic field. The shielding mentioned, for example with ferromagnetic material in the form of a metal sheet, a U-shaped metal sheet, a sandwich of at least two metal sheets or a complete frame, etc., can advantageously be used to implement further improvements in terms of the current sensor module’s susceptibility to interference from magnetic fields that occur in the environment in addition to the magnetic field caused by the current to be measured.

A further preferred embodiment of the current sensor module is characterized in that the current sensors can be separated from the busbar by means of at least one dielectric spacer. In this way, an "air gap" between the busbar and the current sensors remains constant, because the dielectric hardly expands. The dielectric preferably has a high permittivity in order to ensure galvanic isolation even in the case of high voltage differences between the voltage level of the current conductor and that of the current sensors. Examples of suitable materials are glass, FR2, FR4, epoxy resin or ceramics.

A further preferred embodiment of the current sensor module is characterized in that the sensors and their sensor elements are each arranged approximately in the outer third of the busbar. Advantageously, a high level of sensitivity and reaction speed to changes in the current to be measured can be achieved for the current sensors at the positions mentioned, in order in this way to be able to provide an emergency shutdown.

A further preferred embodiment of the current sensor module is characterized in that it also has a signal processing device which an emergency shutdown and a high-precision measurement of the current can be carried out.

A further preferred embodiment of the current sensor module is characterized in that the signal pre-processing can be carried out at least partially by means of the sensors. In this way, the sensors advantageously assume signal preprocessing.

A further preferred embodiment of the current sensor module is characterized in that the signal processing can be carried out entirely by means of the evaluation device. This is how “dumb current sensors” are provided with electrical connections.

A further preferred embodiment of the current sensor module is characterized in that sensors each having a first sensor element of the first magnetic field measurement technology for the emergency shutdown and a second sensor element of the second magnetic field measurement technology can be used for a current measurement.

The invention is described in detail below with further features and advantages on the basis of several figures. Elements that are the same or have the same function have the same reference numbers therein. The figures are intended in particular to clarify the principles that are essential to the invention.

Device features disclosed result analogously from corresponding disclosed method features and vice versa. This means in particular that features, technical advantages and versions relating to the current sensor result from corresponding versions, features and technical advantages relating to the method for operating a current sensor for an electrical energy store and vice versa.

In the figures shows:

1 shows a definition of a coordinate system; Fig. 2 is a plan view of an embodiment of a proposed

current sensor module;

3 is a cross-sectional view of a proposed one

current sensor module; and

4 shows a block diagram of a signal processing chain of the proposed current sensor module.

Description of Embodiments

A current sensor module for an electrical energy store is proposed, with which the following two functions can be implemented in a sensor housing:

- A highly accurate current measurement to determine the state of charge of a battery of an electrically powered motor vehicle

- a magnetic detection of a rapidly increasing current in the event of a fault, which can be a short circuit, for example, and the triggering of a e.g. semiconductor-based circuit breaker to safely isolate the battery from the rest of the circuit

In particular, using the proposed current sensor module, functional safety can be increased through redundancy and verification of the measurement signals, immunity to rectified interference fields that particularly affect the high-precision current measurement, and a very short response time for fault current detection can be provided.

Fig. 1 shows a coordinate system used in connection with the proposed current sensor module 100, in which the x and y axes are located on the surface of an electrical busbar 200 whose current is to be measured, with the y axis pointing in or against the direction of the current flowing. Fig. 2 shows a top view of an embodiment of a proposed current sensor module 100. Two sensors 1, 2 (2D magnetic sensors) can be seen, which are used both for the highly precise current measurement and for the emergency shutdown, which are placed on a printed circuit board 3 to the left and right of the center M at positions with all-pass character of the magnetic field component parallel to the x-direction. The two sensors 1, 2 are each designed to measure a magnetic field using a first measurement technology and using a different second measurement technology. It is provided in particular that one sensor element of the two sensors detects the same or at least essentially the same magnetic field component. For the purpose of signal evaluation, one can also see an integrated evaluation device 4 (e.g. ASIC), which is arranged centrally above busbar 200, external wiring elements 6a...6n and a connecting element 5 (e.g. plug connector) to a higher-level system (e.g. battery management system, not shown).

A high-precision current measurement by means of the current sensor module 100 takes place in a fully differential measuring operation, which can significantly reduce the influence of external magnetic fields or negate it compared to homogeneous magnetic fields. In addition, the detected magnetic fields are verified with the respective other sensor 1, 2, so that, for example, an incorrect triggering of an emergency shutdown can be prevented and the sensor function is ensured at all times and can be monitored. Placing the sensors 1 , 2 with the evaluation circuit 4 in a row perpendicular to the direction of the electric current flow can increase robustness against irradiation and thus against measurement errors and lower the requirements for the wiring on the printed circuit board 3 .

Fig. 3 shows a cross-sectional view of the proposed current sensor module 100. You can see a busbar 200, a spacer 210 arranged on the busbar 200 with a low thermal expansion coefficient and high dielectric constant (e.g. glass, epoxy resin, ceramic, etc.), a printed circuit board 3 (e.g. FR4), and two sensors 1, 2 with sensitive axes in the x and z directions. An area TP indicates arrangement positions of the sensors 1, 2 on the printed circuit board 3 with low-pass behavior for field components in the x-direction. Areas AP indicate positions of the sensors 1, 2 on the printed circuit board 3 with all-pass behavior for field components in the x-direction. HP indicates positions of the sensors 1, 2 on the printed circuit board 3 with high-pass behavior for field components in the x-direction.

The two sensors 1, 2 with sensitive axes in the x and z directions are placed outside the center M of the busbar 200 above the busbar 200, which can be designed, for example, as a connecting line between an electrical energy store (not shown) and an inverter (not shown).

The distance to the center M is determined by the dynamic behavior of the magnetic field, which can be described using known filter behavior. An area should be selected for the emergency shutdown where the field component in the x-direction shows all-pass behavior in order not to burden the measurement process with a delay in detecting an overcurrent. For example, a TMR bridge that is sensitive in the x direction and has a high bandwidth is used to detect the instantaneous field component in the x direction.

In the cross-sectional view of the proposed current sensor module 100, an arrangement of two sensors 1, 2 can be seen, which have sensor elements 1a and 1b or 2a and 2b (not shown), which are designed in different magnetic field measurement technologies, the positioning of which on both sides of the busbar 200 is proposed, with the sensors 1, 2 preferably being arranged in outer edge sections largely symmetrically to the center M, which advantageously achieves redundancy. This is particularly desirable from the point of view of functional safety, since the supply circuit of an electric vehicle with the highest classification is to be protected from malfunctions.

By distributing the precise current measurement and the emergency shutdown, the redundancy affects not only a single functional component, but both. The possibility of using a differential is particularly advantageous Measuring principle of precise current measurement. The magnetic field component perpendicular to the current direction and busbar surface (in the z-direction) has a different sign on both sides of the busbar 200 but the same amplitude as long as there are no high-frequency interferers in the area of influence of the conductor. If both magnetic field signals are subtracted in a central signal evaluation unit, the magnetic field signal is obtained with double the amplitude and external homogeneous magnetic fields are compensated to zero and fields with gradients are reduced to such an extent that only the gradient over the distance between the two sensors under consideration remains as a measurement error, i.e. a maximum of the width of the conductor rail 200, in the specific application rather less. A difference in the amplitudes that results from structural and positional tolerances can be compensated for using a suitable compensation in the evaluation device 4 (not shown), with such a compensation method being known per se.

A second sensor element 1b or 2b, preferably a graph-based Hall sensor, is used in the sensor 1, 2 for the precise detection of the electrical current in the busbar 200, which is installed in the same housing as the first sensor element 1a or 2a in the form of a TMR sensor. Due to the technology, the graphene Hall sensor is sensitive in the z-axis. The x-component of the magnetic field, which acts as a possible measurement error, is not recorded thanks to the almost non-existent cross-field sensitivity of the graph Hall sensor.

An exemplary implementation of a 3D magnetic sensor can include two sensors 1, 2, each with two sensor elements 1a, 1b or 2a, 2b, with the first sensor elements 1, 2a being sensitive parallel to the surface of the substrate, and the second sensor elements 1b, 2b being sensitive to magnetic fields perpendicular to the surface of the substrate. As can be seen in FIG. 2, the first sensor 1 is arranged to the left of the center M and the second sensor 2 to the right of the center M.

The two first sensor elements 1a, 2a differ in their wiring, with one of the two first sensor elements 1a, 2a being sensitive in a first direction and the other of the two first sensor elements 1a, 2a being sensitive in a second direction, which is perpendicular to the first direction, and at the same time lies parallel to the plane of the main extensions of the first sensor elements 1a, 2a. An integrated circuit can lie underneath the functional sensor layers on the surface of a substrate, which is separated from the sensor layers with a passivation layer.

Shielding with ferromagnetic material in the form of a sheet, a U-shaped sheet, a sandwich consisting of two or more sheets, or a complete frame (not shown) can further improve susceptibility to interference from external fields. A specific design, a suitable choice of material and a suitable geometric dimensioning are determined by means of an optimization process. The specific positioning of the sensors 1, 2 to the left and right of the center M of the busbar is preferably such that the emergency shutdown has an all-pass behavior, as a result of which an effect of magnetic diffusion can be counteracted.

If the electrical current in the busbar 200 suddenly increases, e.g. in the case of a short circuit, the current density initially increases at the edge of the busbar 200. This effect is caused by electric current in the center of the conductor being impeded by electric eddy currents generated by the rapid increase in electric current. Before the current has spread throughout the busbar 200, a significant amount of time elapses and a sensor above the center of the busbar 200 only receives the magnetic field that has arisen and only the magnetic field component parallel to the surface of the busbar with a delay compared to the electric current actually flowing. In system theory, this delay is referred to as a low-pass filter or, in special cases, as an integrator. The delay can be so great that a timely emergency shutdown of the affected circuits cannot be guaranteed.

At the edge of the busbar 200, the situation is exactly the opposite. Due to the current distribution, which is concentrated at the edge of the conductor, the magnetic field component parallel to the surface of the busbar 200 initially assumes a higher value than it would assume in the stationary case and a homogeneous current density distribution in the conductor. This crosstalk in the case of rapid changes becomes a system-theoretical high-pass filter or, in special cases, also a differentiator called. Thus, if the magnetic field is delayed in the center above bus bar 200 and tends to crosstalk at the edge of the conductor, there must be a point, lying on an imaginary line parallel to the bus bar surface, where the magnetic field signal neither leads nor lags the current. In system theory, this behavior is referred to as an all-pass.

An optimal position for the sensor element 1, 2 can preferably be determined using FEM (Finite Element Method) and depends on the distance of the measuring point from the busbar surface, the busbar geometry and the environmental conditions such as any shielding. At this optimal point, the sensors 1, 2 are placed in such a way that their sensor elements 1a, 2a are more likely to tend towards high-pass behavior in order to measure a rapid rise in current without delay, possibly somewhat overestimated.

In one variant, the sensors 1, 2 can already have part of the evaluation device 4, so that the emergency shutdown signals and also the measured magnetic field are transmitted on site in a machine-readable format. This is done, for example, on an integrated circuit that is part of the sensor 1, 2. Short supply lines advantageously help to keep measurement errors, e.g. caused by exposure to electromagnetic fields, to a minimum. Compensation for non-linearities and environmental conditions such as temperature can also be carried out very efficiently in this way.

Fig. 4 shows a block diagram of an exemplary signal processing chain of the current sensor module 100. A block diagram of a sensor 1 can be seen with a first sensor element 1a for the emergency shutdown and integrated analog signal evaluation and the precise battery current sensor operated in regulated operation with the sensor element 1b based on graphene Hall. The inputs and outputs of the chip packaged in a package can be purely analog or digital, depending on the specific implementation.

In the upper section of FIG. 4 it can be seen that the first sensor element 1a is operated in an unregulated manner (open-loop arrangement). An output of the first sensor element 1a is connected to an amplification element 6 (e.g. an instrument amplifier ker) out, the output of which is connected to a band limiter 7. An output of the band limiter 7 is connected to a parallel circuit of absolute threshold value detection 8a and differential threshold value detection 8b, whose outputs are routed to a logical OR element 9. A digital one-bit storage element 10 (eg RS flip-flop) stores the output value of the threshold detections 8a, 8b and can be reset via an input 20a. An output 20b represents a status indicator with at least two statuses, which provides status information regarding the occurrence of an error (error flag). An output 20c represents a debugging output that can be used for troubleshooting.

It can be seen in the lower section of Fig. 4 that the second sensor element 1b is used in regulated operation (closed-loop arrangement), with an output of the second sensor element 1b being routed to an amplification element 11 (instrument amplifier), the output of which is connected to a band-limiting element 12. The output of the band limiting element 12 is fed to an analog/digital converter (ADC) 13 which is connected to a controller 14 . An input 20d can be used to configure the controller 14. The output of the regulator 14 is connected to a measuring device 15 which is connected to a digital-to-analog converter (DAC) 16 . An output of the DAC 16 is connected to an amplifier 17 whose output is connected to a magnetic field generator 18 . A highly accurate measured value of the current measured by the current sensor module 100 can be provided at an output 20e.

In a signal processing not shown in the figures, the two technologically diversified sensors 1, 2 each have a TMR sensor in the sensor elements 1a, 2a and a graph sensor in the sensor elements 1b, 2b as well as a magnetic field generator, which ensures both the regulated operation of the high-precision battery current sensors and can be used for a built-in self-test (BIST).

In a variant of the signal processing that is not shown, the two sensors 1, 2 each have a TMR sensor in the sensor elements 1a, 2a and a graph sensor in the sensor elements 1b, 2b as well as a magnetic field generator as well as analog evaluation circuits and a control circuit that ensures both the regulated operation of the high-precision battery current sensors and can be used for the built-in self-test. The distributed sensors are controlled via a central control unit, which can be implemented as an ASIC.

In order to be able to keep signal processing times as short as possible, the emergency shutdown is preferably implemented with analogue, i.e. unclocked and continuous electronic circuits, the output signal being used according to a binary distinction according to its amplitude to distinguish the operating state. The requirements for precise current measurement with regard to the bandwidth to be implemented are significantly lower than with emergency shutdown. Since the focus here is on the precision of the measurement, the measurement signal can be converted into a digital signal as early as possible in the signal path in the integrated circuit. The transmission of such a signal is essentially less error-prone, but there is a time delay compared to analog signals due to the conversion effort and clocking.

However, analog transmission of the signal after compensation for temperature and non-linearities is not ruled out. The use of a 2D material, e.g. graphene, to construct the second sensor element 1b, 2b for the magnetic field component perpendicular to the surface of the busbar 200 almost completely decouples the precise current measurement from the first sensor element 1a, 2a for emergency shutdown. Due to the almost non-existent expansion of the 2D material in the direction of the magnetic field component to be measured, the cross-field sensitivity is almost non-existent. This low cross-field sensitivity combined with the high electron mobility contribute to a sensitive and low-noise sensor.

Compared to the TMR sensors known from the prior art, the noise is again reduced by approximately one order of magnitude, which is what makes precise current measurement with the required accuracy possible. Another contributing factor is that the magnetic field component perpendicular to the busbar surface basically has a low-pass behavior, which further reduces the noise due to an inherent bandwidth limitation. By distributing the sensors 1, 2 on both sides of the busbar 200, the resulting Space in the middle between the sensors 1, 2 can be used for the central signal evaluation. As a result, installation space can advantageously be saved and the line routing is advantageous since no magnetically active surfaces that can contribute to an error need to be spanned.

A magnetic sensor is proposed with magnetoresistance technology, in particular in TMR technology (TMR, tunnel magnetoresistance). Such TM R sensors are constructed using the thin-film process. The production is usually located in the so-called back-end to the ASIC production and can be understood as an add-on process for the production of electrical, integrated circuits, in which additional functional layers are deposited on the ASIC, which together form a sensor.

Among other things, TMR sensors consist of two magnetic and electrically conductive layers that are separated from one another by an electrically non-conductive layer that is only a few atomic layers thick. The reference layer, which essentially forms the magnetic reference layer of a sensor element, is called the fixed layer or reference layer. The magnetic alignment of this reference layer is fixed. If this reference layer is permanently influenced by an external magnetic field, this will destroy the TMR sensor. The magnetically active layer is called the "free layer", whereby the orientation of the free layer is essentially determined by the external magnetic field.

The magnetic tunnel effect describes the probability that electrons will cross the non-conductive tunnel barrier that separates the reference layer and the free layer from one another. The tunneling probability changes depending on the magnetic orientation of the two layers to one another and thus on the respective electron spins. Macroscopically, there is a change in the ohmic resistance of such a TMR resistance element.

If one builds Wheatstone's measuring bridges from such TMR elements, component-dependent arrangements can be implemented depending on the magnetic orientation of the reference layer and the zero position of the free layer, which without additional measures only in the plane of the sensor are strain sensitive. In particular, by using the geometric anisotropy of the free layer, an advantageous zero position can be generated for the individual TMR sensor elements. The Wheatstone bridge resistors consist of several TMR sensors connected in parallel and in series, all of which have the same initial magnetic orientation within the respective bridge resistor.

Depending on the technology used, it is possible to set either just two or four orientations of the reference layers. The orientations of the reference layers can be adjusted using strong magnetic fields with the aid of local heating. This can be carried out using methods known per se (e.g. in an oven, by means of a laser). TMR sensors that are constructed using geometric anisotropy usually have more than one stable operating point. The preferred working point can be left under the influence of high external magnetic fields, so that the sensor finds itself in a less preferred working point. The operating point can be reset to the preferred operating point using a magnetic field generated in the sensor, which is generated, for example, via energized dedicated reset lines.

In order to avoid leaving the preferred operating point when exposed to high fields, the fixed layer can be made up of a nickel-iron layer which, when executed in the correct aspect ratio, forms magnetic vortices (also referred to as vortex). When exposed to an external magnetic field, the center of gravity of the vortex and thus the proportion of parallel to antiparallel electron spins shifts in relation to the reference layer. If the external magnetic field is very large, the magnetic vortex dissolves and forms again by itself when the external field falls below a certain value. TMR sensors are characterized by a large measuring range and low noise, especially in the vortex implementation. Furthermore, TMR sensors have a large measurement bandwidth, regardless of the specific design of the free position, ie they are sensitive to a large frequency range and react very quickly to changes in the magnetic field, which is advantageous for the proposed application in emergency shutdown. In a second back-end process for ASIC production, the graphene is transferred in a manner known per se to a suitable substrate that is connected to the passivation layer of the ASIC (e.g. using a deposition process or using a transfer process).

In this context, graphene is understood to be a 2D material made up of regularly arranged carbon atoms. A 2D material is a material that is only a few atomic layers thick, in particular only a single atomic layer, a so-called monolayer. The material graphene is characterized by a very high electron mobility. This fact particularly contributes to the suitability of graphene as a sensor material using the Hall effect.

The electrons moved by an impressed current are deflected by the Lorentz force created by an external magnetic field acting perpendicularly through the electrically conductive material. This deflection generates a voltage that can be measured at two electrodes or electrical contacts across the applied current and is a measure of the level of the external magnetic field. Due to the high electron mobility, only a small impressed current is necessary to achieve the necessary sensitivity. In particular, the sensitivity can be adjusted to the application by means of the impressed current depending on the current carrying capacity of the sensor. In relation to the external magnetic field, graphene Hall sensors can be adjusted via the size of the active area in the measuring range.

The combination of a TMR sensor and a graphene sensor in a semiconductor component in the form of the sensor 1, 2 enables the representation of a magnetic field sensor that is sensitive in all three spatial directions without having to use a technology to redirect the magnetic field lines.

In the application on which the proposed current sensor module 100 is based, the use of a two-dimensional sensor is advantageous in order on the one hand to measure the magnetic field component perpendicular to the current direction and parallel to the surface of the busbar and on the other hand to measure the magnetic field component perpendicular to the direction of the current and perpendicular to the surface of the busbar.

In the intended application, the solderable or press-fit semiconductor component, which has both a TMR sensor and a graphene Hall sensor as well as an integrated evaluation circuit, is placed both to the left and to the right of the middle of the busbar, such that the TMR sensor is placed in an area where the magnetic field component perpendicular to the current direction and parallel to the surface of the busbar is not delayed compared to the time-dependent current curve, which is e.g. for a configuration without shielding and a distance of the magnetic sensor to the busbar of approx. 5.5 mm is about 75% of half the busbar width.

In order to reduce displacement of the sensor due to the influence of temperature in the room and to achieve sufficient galvanic isolation between the printed circuit board on which the magnetic sensor is mounted and the busbar 200, materials with a low dielectric constant are used for the layers 3, 210, such as glass, epoxy resin or FR2/FR4. The integrated signal evaluation uses an instrumentation amplifier to increase the TMR sensor signal, limits the bandwidth of the TMR sensor signal and evaluates whether a first threshold has been exceeded. The first threshold relates to the amplitude of the magnetic field component, which is related to the electric current actually flowing in the bus bar 200 . The first threshold is adjusted when the sensor system is started up and corrected during runtime according to the temperature prevailing at the measurement location.

The integrated signal evaluation also carries out an evaluation with regard to falling below a second threshold. The second threshold relates to the amplitude of the magnetic field component, which is related to the electric current actually flowing in the bus bar 200 . The second threshold is adjusted when the current sensor module 100 is put into operation and is corrected during the runtime in accordance with the temperature prevailing at the measurement location. Parallel to evaluating the first two thresholds, a real differentiator is used to generate a signal proportional to the slope of the TMR sensor signal, which is compared to a third and fourth threshold. Also this third and fourth Thresholds are adjusted when the sensor system is commissioned and corrected during runtime according to the temperature prevailing at the measurement location.

Depending on the implementation, the threshold values can be set digitally or generated analogously via voltage dividers. Regardless of which threshold value was exceeded or not reached, a one-bit memory component is set, which can be a bipolar multivibrator, an R-S flip-flop or similar, which can only be reset using an external control signal.

In addition to the output of the one-bit memory element, the band-limited sensor signal is made available at an output of the sensor module. The graphene Hall sensor output signal is amplified by an instrumentation amplifier 11 before being band limited by a band limiter 12 . Depending on the actual implementation, the graphene Hall sensor can be operated both in a regulated and in an unregulated manner.

In uncontrolled operation, the band-limited signal is corrected for non-linearity and temperature dependency. This correction preferably takes place in a digital signal processing path. The signal obtained in this way, which is proportional to the magnetic field, can either be output in analog form again or, in order to avoid measurement errors, made available at the output using a digital transmission protocol such as SPI, l ² C or the like.

In controlled operation, the sensor module also has lines with which a magnetic field can be generated perpendicular to the current direction and perpendicular to the busbar surface. The band-limited and digitally converted signal is regulated around its zero point via a correspondingly parameterized control device. The current that is driven through the additional lines serves as the manipulated variable. A measure of the applied external magnetic field is the manipulated variable, which must be recorded and corrected for non-linearity and temperature. The corrected manipulated variable is either output again in analog form or, better to avoid measurement errors, made available at the output using a digital transmission protocol such as SPI, l ² C or the like. In its preferred embodiment, the current sensor module 100 has further current lines which are able to generate a magnetic field in both the direction in which the first sensor element 1a, 2a is sensitive and the direction in which the second sensor element 1b, 2b is sensitive. These lines are used to check the functionality. A second sensor 2 of identical construction is placed with the same orientation at the same distance from the center of the busbar 200 . As a result, a fully redundant system is obtained with regard to the TMR sensors. If there is a need for technology diversity in terms of functional safety, AMR or GMR sensor elements can also be used, which differ from TMR sensors in that they have a slightly modified layer structure, but can also be integrated into the same semiconductor component.

If no external field with a higher frequency acts on the busbar 200 in such a way that electrical eddy currents form, which make the current density distribution within the busbar 200 asymmetrical, both TMR sensors have essentially the same sensor signals within the scope of the differences that result from installation tolerances and differences in components. The graphene Hall sensor signals are also essentially the same in terms of amplitude, but opposite in sign. A fully differential evaluation of the signals of the graphene Hall sensor signals in a central integrated circuit can lead to the doubling of the amplitude and simultaneous cancellation of any external magnetic fields that may have an effect when the two signals are subtracted. In order to achieve a further improvement in the robustness of the sensor signal with respect to external magnetic fields, including those which have gradients, known shielding measures can be taken.

Shielding measures can include a single metal sheet that is attached above the sensor modules and protrudes beyond busbar 200 . Other embodiments of shielding measures are two metal sheets that are mounted above the sensor modules and below the busbar 200, but also the use of a comprehensive U-profile, which is closed below the busbar 200 and open above the sensor modules, or a comprehensive, closed frame that encloses both the busbar 200 and the sensors 1, 2. Known embodiments of Shielding measures use laminated cores instead of solid components to minimize losses due to eddy currents and the influence of the shielding on the measurement signal.

The central evaluation device 4, which is placed centrally above the conductor rail 200, verifies and validates the sensor signals and processes them, such as the subtraction described above. Other functions of the central evaluation unit are communication with the higher-level system using a digital communication protocol.

The central evaluation device 4 can also parameterize the sensors 1 , 2 and the evaluation algorithms. An essential function of the central evaluation device 4 is the determination of the maximum electric current that has flowed in the event of a fault. Since the triggering of a threshold via the change in the output of the bipolar multivibrator is made available directly to the higher-level system, the detection of the electrical current must track this event. The change in the electrical output voltage of the sensor module is detected at an input of the central evaluation device 4, which can release algorithms under hardware control via a trigger, and reading out of the running buffer memory is initiated.

In order to record the maximum current, e.g. twenty values of the buffer memory can be recorded after the error detection has been triggered and the maximum amount of the sensor signal can be stored in a RAM, which can then be read out at a later point in time. The readout takes place according to a specified time cycle, so that the values read out represent a period of time tailored to the application.

Furthermore, the central evaluation device 4 can have the functionality to initiate a built-in self-test and to change its parameterization on command from the higher-level system.

In a centralized embodiment of the proposed current sensor module 100 of the invention, the central evaluation unit can be expanded to include the functionality of controlling the graph Hall sensor. The proposed current sensor module 100 advantageously provides a highly accurate and fast battery current sensor measuring instrument that can measure the electric current supplied to and drawn from the battery, which means that a very precise display of the battery's state of charge can be implemented as a result.

The person skilled in the art can also implement embodiments of the invention that are not disclosed or only partially disclosed without departing from the core of the invention.

Claims

Expectations . Current sensor module (100) for an electrical energy store, comprising:

- at least one first sensor (1) having two sensor elements (1a, 1b), wherein a first sensor element (1a) of the first sensor (1) is formed using a first magnetic field measurement technology and a second sensor element (1b) of the first sensor (1) is formed using a second magnetic field measurement technology;

- At least one second sensor (2) having two sensor elements (2a, 2b), wherein a first sensor element (2a) of the second sensor (2) is formed using a first magnetic field measurement technology and a second sensor element (2b) of the second sensor (2) is formed using a second magnetic field measurement technology, wherein sensing directions of the first and second sensor elements (1a, 1b, 2a, 2b) are arranged perpendicular to one another;

- A printed circuit board (3) on which the two sensors (1, 2) are arranged in a galvanically conductive manner; and

- an evaluation device (4) with which the measured values of the two sensors (1, 2) can be evaluated separately from one another, in which case an indirect measurement of the current can be carried out from magnetic field measurements of the two sensors (1, 2), the printed circuit board (3) being mounted on a busbar (200) of the electrical energy store in such a way that when the current sensor module (100) is installed in the intended position on the busbar (200) of the electrical energy store, one sensor (1, 2nd ) is arranged in an edge section of the busbar. . Current sensor module (100) according to Claim 1, further comprising a connector (5) arranged on the printed circuit board (3) for connecting the current sensor module (100) to a higher-level system. . Current sensor module (100) according to claim 1 or 2, characterized in that the first magnetic field measurement technology of the first sensor elements (1a, 2a) is one of: TMR, AMR, GMR. Current sensor module (100) according to one of the preceding claims, characterized in that the second magnetic field measurement technology of the second sensor elements (1b, 2b) is based on the Hall effect, in particular using graphs. Current sensor module (100) according to one of the preceding claims, characterized in that a sensor signal of the first sensor element (1a) is evaluated in relation to a first upper threshold value of an amplitude of a magnetic field component which is related to an electric current flowing in the busbar (200), that a sensor signal of the first sensor element (1a) is evaluated in relation to a second lower threshold value of the amplitude of the magnetic field component which is related to an electric current flowing in the busbar 200, that a change speed of a sensor signal of the first sensor element (1a) compared to a third upper threshold value of an amplitude of the magnetic field component, which is related to an electric current flowing in busbar 200, and that the rate of change of the sensor signal of the first sensor element (1a) is evaluated compared to a fourth lower threshold value of an amplitude of the magnetic field component, which is related to an electric current flowing in busbar 200. Current sensor module (100) according to Claim 5, characterized in that a sensor signal is evaluated in the same way for the second sensor element (2a) as for the first sensor element (1a) from the magnetic field component resulting from the electric current flowing in the electric busbar (200). Current sensor module (100) according to one of the preceding claims, further comprising at least one shielding element against an external electromagnetic field. Current sensor module (100) according to one of the preceding claims, characterized in that the current sensor module (100) can be electrically isolated from the busbar (200) by means of at least one dielectric spacer (210). Current sensor module (100) according to any one of the preceding claims, characterized in that the sensors (1, 2) are arranged approximately in the outer third of the busbar (200). Current sensor module (100) according to one of the preceding claims, further comprising a signal processing device, with which an emergency shutdown and a measurement of the current are carried out. Current sensor module (100) according to any one of the preceding claims, characterized in that at least one signal pre-processing by means of the sensors (1, 2) is carried out. Current sensor module (100) according to claim 11, characterized in that the signal processing is carried out entirely by means of an evaluation device (4) throughc. Current sensor module (100) according to one of the preceding claims, characterized in that a first sensor element (1a, 2a) of the first magnetic field measurement technology for the emergency shutdown and a second sensor element (1b, 2b) of the second magnetic field measurement technology for the high-precision current measurement is used. Method for operating a current sensor module (100) for an electrical energy store, comprising the steps:

- Determining a magnetic field with a first sensor (1) with a first sensor element (1b) of a first magnetic field measurement technology;

- Determining a magnetic field with a second sensor (2) with a first sensor element (2b) of the first or a second magnetic field measurement technology, the measurements of the two sensors (1, 2) being evaluated separately from one another; and

- Determining a current flow for an electrical energy store from the determined magnetic fields. The method of claim 14, wherein the first sensor (1) with the first sensor element (1a) performs a measurement of a magnetic field component, wherein a sensor signal of the first sensor element (1a) compared to a first upper threshold value of an amplitude of a magnetic field component, which is related to an electric current flowing in the busbar (200), is evaluated, a sensor signal of the first sensor element (1a) being evaluated compared to a second lower threshold value of the amplitude of the magnetic field component, which is related to an electric current flowing in the busbar 200, wherein a rate of change of a sensor signal of the first sensor element (1a) is compared to a third upper threshold value of an amplitude of the magnetic field component, which is related to a current in the busbar 200 flowing electric current is evaluated, wherein the rate of change of the sensor signal of the first sensor element (1a) is evaluated against a fourth lower threshold value of an amplitude of the magnetic field component, which is in relation to an electric current flowing in the busbar 200, whereby a sensor signal is evaluated for the second sensor element (2a) in the same way as for the first sensor element (1a) from the magnetic field component resulting from the electric current flowing in the electric busbar (200), whereby in the case that the measured values of both sensor elements (1a, 2a) violate at least one of the threshold values and the current flow determined has a defined value, an emergency shutdown is triggered.