DE102022208535A1 - Method for determining a functional relationship between a drive unit and a vehicle - Google Patents

Abstract

The invention relates to a method for determining a speed of a vehicle and a vehicle, in particular a single-track vehicle such as a pedelec, the vehicle having an electric drive unit, a magnetic field sensor and a magnet arranged on a wheel of the vehicle, comprising:- a control device for operating the electric drive unit of the vehicle at several load points by changing at least one operating variable such as current intensity and/or speed, - a first determination device, designed to determine a functional relationship between a specific interfering magnetic field and the at least one operating variable, - a measuring device, comprising the magnetic field sensor, which is designed to measure a time profile of a magnetic field by means of the magnetic field sensor and the at least one operating variable of the drive unit, such as a current intensity of the drive unit and/or a speed of the drive unit - a compensating device designed to compensate for the measured time profile of the magnetic field based on the functional relationship and the at least one measured operating variable of the drive unit, - a second determination device designed to determine the speed of the vehicle based on the compensated time profile of the magnetic field.

Description

The invention relates to a method for determining a functional relationship of a drive unit.

The invention further relates to a method for checking the plausibility of a time profile of a magnetic field in a vehicle, in particular a single-track vehicle such as a pedelec, by compensating for an interfering magnetic field of an electric drive unit of the vehicle.

The invention also relates to a method for determining a speed of a vehicle, in particular a single-track vehicle such as a pedelec, the vehicle having an electric drive unit, a magnetic field sensor and a magnet arranged on a wheel of the vehicle.

The invention further relates to a vehicle, in particular a single-track vehicle such as a pedelec, the vehicle having an electric drive unit, a magnetic field sensor and a magnet arranged on a wheel of the vehicle.

Although generally applicable to vehicles, the present invention is explained using pedelecs.

State of the art

To determine the speed of vehicles, it has become known to attach a magnet to a wheel. With each rotation of the wheel, the magnetic field is detected by a magnetic field sensor as it rotates or runs past it. The speed of the vehicle can be calculated from the time interval between successive detections by the magnetic field sensor and the wheel diameter.

In the case of pedelecs in particular, the magnetic field sensor is often arranged in the vicinity of or in the drive unit. Due to the developments in the pedelec sector, the power densities of the drive units are increasing, while the installation space for shielding elements is becoming smaller. This increases the probability that a magnetic field generated by the drive unit, in particular by an electric motor, will interfere with the magnetic field sensor. It is therefore possible that the magnetic field sensor does not detect the magnet rotating past based on its magnetic field, or detects a magnetic field that is not actually generated by the magnet on the wheel.

Disclosure of Invention

• - Betreiben der elektrischen Antriebseinheit in mehreren Lastpunkten durch Verändern von zumindest einer Betriebsgröße wie Stromstärke und/oder Drehzahl,
• - Bestimmen eines von der Antriebseinheit erzeugten Störmagnetfelds, insbesondere eines durch einen Stator der Antriebseinheit erzeugten Störmagnetfelds, in den mehreren Lastpunkten,
• - Ermitteln eines funktionalen Zusammenhangs des bestimmten Störmagnetfeldes mit der zumindest einen Betriebsgröße der Antriebseinheit.

In one embodiment, the present invention provides a method for determining a functional relationship of a drive unit, comprising the steps:

• - Operating the electric drive unit at several load points by changing at least one operating variable such as current and/or speed,
• - Determination of an interference magnetic field generated by the drive unit, in particular an interference magnetic field generated by a stator of the drive unit, in the several load points,
• - Determination of a functional relationship between the determined interference magnetic field and the at least one operating variable of the drive unit.

• - Messen eines zeitlichen Verlaufs eines Magnetfelds mittels des Magnetfeldsensors und von der zumindest einen Betriebsgröße der Antriebseinheit,
• - Kompensieren des gemessenen zeitlichen Verlaufs des Magnetfelds anhand des funktionalen Zusammenhangs sowie der zumindest einen gemessenen Betriebsgröße der Antriebseinheit.

In one embodiment, the present invention provides a method for checking the plausibility of a time profile of a magnetic field in a vehicle, in particular a single-track vehicle such as a pedelec, by compensating for an interference magnetic field of an electric drive unit of the vehicle, the vehicle having a magnetic field sensor and one on a wheel of the Vehicle arranged magnets, wherein a functional relationship of a specific magnetic interference field with at least one operating variable of the drive unit such as the current and / or the speed is determined by a method according to any one of claims 1-7, comprising the steps:

• - Measuring a time profile of a magnetic field by means of the magnetic field sensor and of the at least one operating variable of the drive unit,
• - Compensate for the measured time profile of the magnetic field based on the functional relationship and the at least one measured operating variable of the drive unit.

• - Ermitteln der Geschwindigkeit des Fahrzeugs anhand des kompensierten zeitlichen Verlaufs des Magnetfelds.

In one embodiment, the present invention provides a method for determining a speed of a vehicle, in particular a single-track vehicle such as a pedelec, the vehicle having an electric drive unit, a magnetic field sensor and a magnet arranged on a wheel of the vehicle, with a time profile of a magnetic field measured by the magnetic field sensor is compensated by a method according to any one of claims 8-9, comprising the step:

• - Determining the speed of the vehicle based on the compensated time profile of the magnetic field.

• - eine Steuereinrichtung, ausgebildet zum Betreiben der elektrischen Antriebseinheit des Fahrzeugs in mehreren Lastpunkten durch Verändern zumindest einer Betriebsgröße wie Stromstärke und/oder Drehzahl,
• - eine erste Ermittlungseinrichtung, ausgebildet zum Ermitteln eines funktionalen Zusammenhangs eines bestimmten Störmagnetfeldes mit der zumindest einen Betriebsgröße,
• - eine Messeinrichtung, umfassend den Magnetfeldsensor, welche zum Messen eines zeitlichen Verlaufs eines Magnetfelds mittels des Magnetfeldsensors sowie von der zumindest einen Betriebsgröße der Antriebseinheit wie einer Stromstärke der Antriebseinheit und/oder einer Drehzahl der Antriebseinheit ausgebildet ist,
• - eine Kompensiereinrichtung, ausgebildet zum Kompensieren des gemessenen zeitlichen Verlaufs des Magnetfelds anhand des funktionalen Zusammenhangs sowie der zumindest einen gemessenen Betriebsgröße der Antriebseinheit,
• - eine zweite Ermittlungseinrichtung, ausgebildet zum Ermitteln der Geschwindigkeit des Fahrzeugs anhand des kompensierten zeitlichen Verlaufs des Magnetfelds und insbesondere
• - eine Bestimmungseinrichtung, ausgebildet zum Bestimmen des von der Antriebseinheit erzeugten Störmagnetfelds, insbesondere eines durch einen Stator der Antriebseinheit erzeugten Störmagnetfelds, in den mehreren Lastpunkten.

In one embodiment, the present invention provides a vehicle, in particular a single-track vehicle such as a pedelec, the vehicle having an electric drive unit, a magnetic field sensor and a magnet arranged on a wheel of the vehicle, comprising:

• - a control device, designed to operate the electric drive unit of the vehicle in several load points by changing at least one operating variable such as current and / or speed,
• - a first determination device, designed to determine a functional relationship between a specific interference magnetic field and the at least one operating variable,
• - a measuring device, comprising the magnetic field sensor, which is designed to measure a time profile of a magnetic field by means of the magnetic field sensor and the at least one operating variable of the drive unit, such as a current intensity of the drive unit and/or a speed of the drive unit,
• - a compensation device, designed to compensate for the measured time profile of the magnetic field based on the functional relationship and the at least one measured operating variable of the drive unit,
• - A second determination device, designed to determine the speed of the vehicle based on the compensated time profile of the magnetic field and in particular
• - a determination device, designed to determine the interfering magnetic field generated by the drive unit, in particular an interfering magnetic field generated by a stator of the drive unit, in the plurality of load points.

One of the advantages achieved in this way is that interfering magnetic fields of the drive unit can be described in a simple manner by means of a functional relationship and, moreover, can be compensated for. As a result, measured values, for example a time profile of magnetic fields, can then be checked for plausibility. Another advantage is that the speed of the vehicle can be reliably determined. In particular, a speed can be determined reliably by means of a magnet arranged on a wheel of a vehicle and by sensing the passage of a corresponding sensor, even if an adjacent drive unit influences the magnetic field of the magnet.

In general, a vehicle can determine the functional relationship between a measured magnetic field and at least one operating variable of the electric drive unit and, based on the determined relationship, compensate the measured time profile of the magnetic field, so that a speed measurement can be carried out more accurately. It is also possible that the functional relationship between a measured magnetic field and the operating variable of the electric drive unit is determined independently of the vehicle, for example as part of a calibration of the drive unit after production, and the functional relationship is then stored in the drive unit. Based on this functional relationship, the speed of a vehicle on which the drive unit is arranged can be determined. Furthermore, the influences of the drive unit on other magnetic field-based sensors in a vehicle, such as a torque sensor, can be compensated.

The “measurement of a time profile of a magnetic field by means of the magnetic field sensor” can take place in at least one direction and/or include a measurement of an overall magnetic field. In particular, the course of the magnetic field over time is measured in the same direction as when determining the interfering magnetic field of the drive unit.

The term "magnetic field sensor" is to be understood in the broadest sense. In particular, any sensor that can be influenced by magnetic fields is to be understood as a magnetic field sensor within the meaning of embodiments of the invention. For example, a torque sensor that is based on a magnetic operating principle is a magnetic field sensor.

Other features, advantages, and other embodiments of the invention are described below or will become apparent thereby.

According to an advantageous development of the invention, the functional relationship is determined by generating at least one characteristic diagram of the interfering magnetic field and the operating parameters of the drive unit, such as the current intensity of the drive unit and/or the speed of the drive unit. Based on the various load points, a map can be generated. An interference magnetic field generated by the drive unit at a specific load point can be determined in a simple manner by means of the characteristics map. In particular, the map can be based on a drive unit other than the drive unit of the driver be determined because drive units with a similar structure produce a similar map.

According to an advantageous development of the invention, at least one function that approximately describes the characteristic map is determined. Such an approximation function, which describes the family of characteristics, allows a magnetic interference field to be calculated in a simple manner and then compensated for. In particular, it is also possible to calculate and compensate for magnetic interference fields from load points that are not directly recorded in the characteristic map, for example if the load point lies between two specific load points in the characteristic map.

According to an advantageous development of the invention, information about the determined functional relationship, in particular the at least one function and/or the at least one characteristic diagram, is stored in the drive unit. An advantage of this is that the relationship, the function and/or the characteristic map can be determined once and can then be used. In particular, a relationship, a map and/or a function can be determined based on a drive unit other than the drive unit of the vehicle and the relationship, the map and/or the function can then be stored in a memory of the vehicle. It is also conceivable that a separate functional relationship is generated for each drive unit, for example as part of a calibration after production, and that this is stored in a memory of the drive unit. If the drive unit is placed in a vehicle, the functional relationship can also be stored in the vehicle's memory.

According to an advantageous development of the invention, the functional relationship between an amplitude of the interfering magnetic field and/or a phase of the interfering magnetic field is determined with a current strength of the drive unit and/or a speed of the drive unit. The interference magnetic field can be described as a function of a phase and an amplitude. In this case, in particular, two characteristic diagrams and/or two functions can be determined, each depending on the amplitude of the characteristic diagram and the phase of the characteristic diagram. The advantage of this is that the interfering magnetic field can be determined more precisely.

According to an advantageous development of the invention, the functional relationship, in particular in the form of a function and/or a characteristic map, is determined while the drive unit is being operated in a vehicle. An advantage of this is that the function/map does not have to be saved, but is created directly while driving. It is also conceivable that the function/the characteristic map is stored in a corresponding memory in the vehicle and/or the drive unit after it has been generated. An advantage of this is that there is no need for post-production calibration.

According to an advantageous development of the invention, the functional relationship, in particular in the form of a function and/or a characteristic map, is determined while the drive unit is being operated outside of a vehicle. An advantage of this is that the functional relationship can be determined after production, for example. The functional relationship can then be stored in the drive unit. The drive unit can thus already be calibrated or delivered with a determined function/characteristic map.

According to an advantageous development of the invention, the measured profile of the magnetic field is compensated using a rotor position of the drive unit. In an electric drive unit, magnetic interference fields can be created by a stator and/or a rotor. The interference fields from the rotor depend on the speed of the rotor and the rotor position. A characteristic field can thus be generated which describes a relationship between the rotational speed of the rotor, the rotor position and the resulting interference magnetic field. Based on this relationship, a detected magnetic field can be compensated. The characteristic map can be generated in particular by modulation of the load points in the vehicle. An advantage of this is that further interference fields can be compensated.

According to an advantageous development of the invention, determining the speed includes detecting a flank in the course of the measured magnetic field over time. One advantage of this is that it can be reliably detected whether the magnet is rotating past the magnetic field sensor. In particular, disturbances in the measured magnetic field, which can cause the magnet to be detected incorrectly, can be compensated for.

• - Ermitteln von Hoch- und Tiefpunkten im zeitlichen Verlauf des Magnetfelds,
• - Ermitteln einer Flanke anhand der zeitlichen Abfolge eines Hoch- und Tiefpunkts, und
• - Vergleichen der Amplitude der ermittelten Flanke mit zumindest einem Schwellwert, wobei die ermittelte Flanke als erkannt gilt, wenn die Amplitude der ermittelten Flanke größer ist als ein erster kleinerer Schwellwert und/oder größer ist als ein zweiter größerer adaptiver Schwellwert.

According to an advantageous development of the invention, the detection of an edge includes the steps:

• - Determination of high and low points over time in the magnetic field,
• - Determining an edge based on the time sequence of a high and low point, and
• - Comparing the amplitude of the determined edge with at least one threshold value, the determined edge being considered to be recognized, if the amplitude of the determined edge is greater than a first, smaller threshold value and/or is greater than a second, larger adaptive threshold value.

One of the advantages achieved in this way is that a robust and at the same time reliable generation of a time signal for determining a speed of the vehicle is made possible. At the same time, flexibility is increased since greater tolerances are made possible when arranging the sensor and magnet, which also reduces the manufacturing costs and the time required for assembly. An adaptive threshold value is, in particular, a threshold value that can be changed while driving, for example based on determined edges.

According to an advantageous development of the invention, before the edge is detected, the values of the measured magnetic field are processed, in particular filtered, preferably by means of a bandpass filter, with a stopband and passband of the bandpass filter being adapted to a specified rotational frequency of the wheel of the vehicle. The advantage of this is that, for example, outliers or the like can be filtered out, which improves the reliability of the detection of edges.

According to an advantageous development of the invention, a time stamp is generated and/or a counter is increased when an edge is detected. One advantage of this is that the time interval between two flanks can be determined in a simple manner, so that the speed of the vehicle can be determined on this basis.

According to an advantageous development of the invention, the magnetic field is measured in at least two spatial directions and the values of the magnetic field measured in at least two spatial directions are rotated into a main axis of the magnetic fields before a flank is detected, in particular the angle of the main axis for the rotation is based on values of the magnetic field is determined in a second spatial direction. "Spatial direction" is synonymous to understand a "spatial axis". This increases the useful amplitude for detecting flanks, which further improves overall reliability.

According to an advantageous development of the invention, a time profile of a vector of the magnetic field is also evaluated to evaluate the rising and/or falling edges, in particular to check their plausibility. The advantage of this is that it improves edge detection even further.

• - Wenn die mögliche Geschwindigkeit oberhalb eines vorgebbaren Schwellwerts liegt, wird die ermittelte Flanke verworfen.
• - Wenn der Gradient der ermittelten Flanke unterhalb eines Schwellwerts liegt, wird die ermittelte Flanke verworfen.
• - Wenn die Zeitdifferenz zwischen dem Tiefpunkt der ermittelten Flanke und dem Zeitpunkt des Überschreitens eines Schwellwerts in dem Flankenverlauf oberhalb eines vorgebbaren Schwellwerts ist, wird die ermittelte Flanke verworfen.
• - Wenn die Fahrzeugbeschleunigungen, berechnet aus einer aktuell ermittelten Flanke und einer früheren Flanke, oberhalb eines vorgebbaren Schwellwerts liegen, wird die aktuell ermittelte Flanke verworfen.

According to an advantageous development of the invention, a possible speed is calculated based on the edge determined and the edge is checked for plausibility based on at least one of the following conditions using a plausibility check method:

• - If the possible speed is above a specifiable threshold value, the edge determined is discarded.
• - If the gradient of the edge determined is below a threshold value, the edge determined is discarded.
• - If the time difference between the low point of the determined edge and the point in time at which a threshold value in the edge profile is exceeded is above a predefinable threshold value, the determined edge is discarded.
• If the vehicle accelerations, calculated from a currently determined edge and an earlier edge, are above a predefinable threshold value, the currently determined edge is discarded.

This improves the robustness of the method, since any detected edges are checked for plausibility. For example, flanks that would imply an unrealistically high speed of the vehicle can be discarded.

According to an advantageous development of the invention, the plausibility checking method includes an edge prediction, in particular based on acceleration data of the vehicle, so that a recognized edge is rejected as implausible if no edge is predicted based on the acceleration data. The reliability of the edge detection can thus be improved.

According to an advantageous development of the invention, to identify the polarization of the magnet, a predeterminable number of edges are determined and, in particular, an angular profile of the magnetic field vector is determined, with the polarization being determined based on a comparison of the maximum amplitude of the rising and the falling amplitude, with when the maximum falling amplitude is greater than the maximum rising amplitude, the polarization of the magnet is assumed to be reversed and the measured values of the magnetic field are inverted, the polarization being evaluated in particular using a predeterminable number of rising and/or falling edges. When installing the magnet, the magnet could be installed rotated by 180°. This reverses the polarity of the magnet. This can be recognized from the course of the flanks become. The advantage of this is that the magnet can be installed in both directions.

According to an advantageous development of the invention, the first determination device is designed to determine the functional relationship from a memory of the vehicle, in particular a memory of the drive unit. One advantage of this is that the functional relationship can be stored in the vehicle and a new determination can therefore be omitted. In particular, the functional relationship can already be stored in the drive unit when it is arranged on the vehicle. It is thus possible to dispense with determining the functional relationship by the vehicle.

Further important features and advantages of the invention result from the dependent claims, from the drawings and from the associated description of the figures.

It goes without saying that the features mentioned above and those still to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

Preferred designs and embodiments of the invention are shown in the drawings and are explained in more detail in the following description, with the same reference symbols referring to identical or similar or functionally identical components or elements.

• 1 Schritte eines Verfahrens gemäß einer Ausführungsform der vorliegenden Erfindung,
• 2 Schritte eines Verfahrens gemäß einer weiteren Ausführungsform der vorliegenden Erfindung,
• 3 einen Verlauf eines kompensierten Magnetfelds gemäß einer Ausführungsform der vorliegenden Erfindung,
• 4 ein Kennfeld gemäß einer Ausführungsform der vorliegenden Erfindung,
• 5 einen Verlauf eines Magnetfelds mit erkannten Flanken gemäß einer Ausführungsform der vorliegenden Erfindung,
• 6 einen Teil eines Fahrzeugs gemäß einer Ausführungsform der vorliegenden Erfindung, und
• 7 ein Fahrzeug gemäß einer Ausführungsform der vorliegenden Erfindung.

It shows in schematic form

• 1 Steps of a method according to an embodiment of the present invention,
• 2 Steps of a method according to a further embodiment of the present invention,
• 3 a course of a compensated magnetic field according to an embodiment of the present invention,
• 4 a map according to an embodiment of the present invention,
• 5 a course of a magnetic field with detected flanks according to an embodiment of the present invention,
• 6 a part of a vehicle according to an embodiment of the present invention, and
• 7 a vehicle according to an embodiment of the present invention.

1 Figure 12 shows, in schematic form, steps of a method according to an embodiment of the present invention.

1 shows steps of a method for determining a speed of a vehicle, the vehicle having an electric drive unit, a magnetic field sensor and a magnet arranged on a wheel of the vehicle.

In a step S1, an electric drive unit is operated at a number of load points by changing at least one operating variable of the drive unit, such as current intensity and/or speed. The electric drive unit can be the vehicle's drive unit or a test drive unit. This is operated at different load points, which means that the operating parameters of the drive unit, such as current and speed, are changed in discrete steps.

bestimmt.In a further step S2, an interference magnetic field generated by the drive unit, in particular an interference magnetic field generated by a stator of the drive unit, is determined in the multiple load points. The magnetic field generated by the drive unit is determined for each load point. In particular, the amplitude and the phase of the magnetic field are determined. These can, for example, be entered in a map in connection with the current strength and the speed. For example, the phase of the magnetic field is related to the angle of the current vector. The angle of the current pointer is calculated using the formula $${\phi }_{}$$$${}_0=atan2\left(I_{\beta },I_a\right)$$

certainly.

• φ₀: Der Winkel des Stromzeigers im Stator
• I_β, I_α: Die Statorströme in α, β - Koordinaten

there is

• φ ₀ : The angle of the current vector in the stator
• I _β , I _α : The stator currents in α, β - coordinates

In a further step S3, a functional relationship between the determined interference magnetic field and the at least one operating variable of the drive unit is determined. It is possible that the interference magnetic field is determined based on the amplitude and the phase. In this case, two functional relationships can be determined. First, the relationship between the amplitude of the magnetic field and the operating parameters, and second, the relationship between the phase of the magnetic field and the operating parameters. The functional relationships can be determined, for example, using characteristic diagrams. Be particular Functions are calculated that describe the points in the map as precisely as possible. This gives two functions that can be used to calculate the magnetic field amplitude and phase for any load point. These functions are stored in the vehicle or in the drive unit.

In a further step S4, a time profile of a magnetic field is measured using the magnetic field sensor and the at least one operating variable of the drive unit, such as a current intensity of the drive unit and/or a speed of the drive unit. The course of the magnetic field over time is measured by the vehicle's magnetic field sensor and can therefore be influenced by the interfering magnetic field of the drive unit. In other words, the course over time of the measured magnetic field does not just correspond to the course over time of the magnetic field generated by the magnet.

Therefore, in a further step S5, the measured time profile of the magnetic field is compensated based on the functional relationship and the at least one measured operating variable of the drive unit. The operating variables such as the current intensity and the speed of the drive unit are known from step S4, so that the magnetic interference field of the drive unit can be determined based on the function determined in step S3. The determined disturbance of the magnetic field is subtracted from the measured magnetic field so that the resulting magnetic field corresponds to the actual magnetic field of the magnet. For example, the compensated magnetic field can be calculated using the following formulas: $$\begin{array}{c}Ma{G}_{kOmp}=Ma{G}_{SensO\mathrm{right}}-Ma{G}_{Ant\mathrm{right}ieb}\\ Ma{G}_{Ant\mathrm{right}ieb}=A*\text{cos}\left({\phi }_0-\phi \right)\end{array}$$

• Mag_komp: Das kompensierte Magnetfeld
• Mag_Sensor: Das vom Magnetfeldsensor ermittelte Magnetfeld
• Mag_Antrieb: Das von der Antriebseinheit erzeugte Störmagnetfeld
• A: Die Amplitude des von der Antriebseinheit erzeugten Magnetfelds
• φ: Die Phase des von der Antriebseinheit erzeugten
• Magnetfelds bezogen auf den Winkel des Stromzeigers
• φ₀: Der Winkel des Stromzeigers im Stator

where:

• Mag _comp : The compensated magnetic field
• Mag _Sensor : The magnetic field detected by the magnetic field sensor
• Mag _Drive : The disturbance magnetic field generated by the drive unit
• A: The amplitude of the magnetic field generated by the drive unit
• φ: The phase of the generated by the drive unit
• magnetic field related to the angle of the current vector
• φ ₀ : The angle of the current vector in the stator

Since the course of the measured magnetic field has been corrected for the interfering influences and essentially corresponds to the course of the magnetic field of the magnet, the speed of the vehicle can be determined therefrom in a further step S6.

2 Figure 12 shows, in schematic form, steps of a method according to another embodiment of the present invention.

2 shows steps of a method for checking the plausibility of measured values of a magnetic field sensor in a vehicle, in particular a single-track vehicle such as a pedelec, by compensating for interfering magnetic fields of an electric drive unit of the vehicle.

Follow the procedure according to steps S1 to S5 1 In particular, a magnetic field sensor used to determine a speed can be cleaned of interference. However, it is also possible for other magnetic field-based sensors, for example a torque sensor, to be disrupted by the electric drive unit of the vehicle. This disturbance can also be compensated for.

• - Betreiben S1' einer elektrischen Antriebseinheit, insbesondere der elektrischen Antriebseinheit des Fahrzeugs, in mehreren Lastpunkten durch Verändern von zumindest einer Betriebsgröße wie Stromstärke und/oder Drehzahl,
• - Bestimmen S2' eines von der Antriebseinheit erzeugten Störmagnetfelds, insbesondere eines durch einen Stator der Antriebseinheit erzeugten Störmagnetfelds, in den mehreren Lastpunkten,
• - Ermitteln S3' eines funktionalen Zusammenhangs des bestimmten Störmagnetfeldes mit der zumindest einen Betriebsgröße der Antriebseinheit,
• - Messen S4' eines zeitlichen Verlaufs eines Magnetfelds mittels des Magnetfeldsensors und von der zumindest einen Betriebsgröße der Antriebseinheit wie einer Stromstärke der Antriebseinheit und/oder einer Drehzahl der Antriebseinheit,
• - Kompensieren S5' des gemessenen zeitlichen Verlaufs des Magnetfelds anhand des funktionalen Zusammenhangs sowie der zumindest einen gemessenen Betriebsgröße der Antriebseinheit.

In particular, the disruption can be compensated for using the following steps so that the measured values of the magnetic field sensor are checked for plausibility:

• - Operating S1 'an electric drive unit, in particular the electric drive unit of the vehicle, in several load points by changing at least one operating variable such as current and / or speed,
• - Determination S2' of an interference magnetic field generated by the drive unit, in particular an interference magnetic field generated by a stator of the drive unit, in the several load points,
• - Determining S3 'a functional relationship of the determined interference magnetic field with the at least one operating variable of the drive unit,
• - Measuring S4' a time profile of a magnetic field by means of the magnetic field sensor and of the at least one operating variable of the drive unit such as a current intensity of the drive unit and/or a speed of the drive unit,
• - Compensating S5 'of the measured time profile of the magnetic field based on the functional relationship and the at least one measured operating variable of the drive unit.

The steps S1 'to S5' can in particular the steps S1 to S5 according to 1 are equivalent to.

3 shows in schematic form a course of a compensated magnetic field according to an embodiment of the present invention.

Diagram 300 shows the course of a magnetic field 303 measured by a magnetic field sensor (not shown), an interference magnetic field 304 generated by a drive unit (not shown) and a compensated magnetic field 305. The X-axis 301 shows the angle of the current vector in radians and the Y -axis the magnetic flux density in µT.

The compensated magnetic field 305 corresponds to the difference between the magnetic field 303 measured by the magnetic field sensor and the interfering magnetic field 304 generated by the drive unit. Due to measurement inaccuracies, for example, it is possible that the interfering magnetic field cannot be completely compensated and a proportion of the interference in the compensated magnetic field 305 remains. Based on the compensated magnetic field 305, the speed of a vehicle can be determined, for example.

The amplitude 306 of the interfering magnetic field 304 can be greater than the amplitude of the magnetic field generated by a magnet rotating past and in particular greater than the amplitude 307 of the compensated magnetic field 305. This means that, for example, in the case of a magnetic field-based speed sensor, the drive unit could generate such a strong magnetic field that the speed sensor detects the magnet rotating past, although the magnet arranged on a wheel of a vehicle is not in the vicinity of the magnetic field sensor. The influence of the drive unit is reduced by the compensation.

4 12 shows, in schematic form, a map according to an embodiment of the present invention.

Diagram 400 shows a characteristic map of a drive unit of a vehicle (not shown). The map can, for example, by performing steps S1 and S2 according to 1 be generated. In particular, the drive unit is run at different load points and the current intensity, the speed and the interfering magnetic field are measured in each case. The resulting pairs of values can then be entered in the map.

The X-axis 401 shows the current in amperes, the Y-axis 402 shows the motor speed in revolutions per minute and the Z-axis 403 shows the magnetic flux density in μT.

A connection between the current intensity, the speed and the magnetic flux density can be determined from the characteristic map. For example, it can be seen that the magnetic flux density decreases with increasing speed and constant current strength. At the same time, it can be seen that the magnetic flux density increases with constant speed and increasing current strength.

This relationship can be described by a mathematical function. The function thus allows the resulting magnetic field amplitude - i.e. the strength of the interfering magnetic field - to be determined for any combination of speed and current strength. In particular, the difference between a magnetic flux density determined from the map and a corresponding magnetic flux density calculated by the function is as small as possible at each load point, so that the function describes the map as precisely as possible.

This function can then be stored in a memory of the vehicle in which the drive unit is arranged. It is also possible for the function to be stored in a memory of another vehicle that has a drive unit that is structurally similar to the drive unit. It is also possible for the function to be stored in a memory of the drive unit, for example when the drive unit is not yet arranged on a vehicle.

5 shows a course of a magnetic field with recognized flanks according to an embodiment of the present invention.

Diagram 500 shows a time profile of values from a magnetic field sensor (not shown). The X-axis 501 shows the time in seconds and the Y-axis 502 shows the magnetic flux density in μT.

Steps S1 to S6 according to FIG 1 be performed. In step S6 according to 1 the speed is determined based on the course of the compensated magnetic field. For example, the speed can be determined by the time interval between magnetic field peaks in the course of the compensated magnetic field. Compensation reduces interference from the drive unit. However, the compensated can Magnetic field may be influenced by other magnetic fields, so that a correct detection of magnetic field peaks in the course of the compensated magnetic field may be difficult.

Edges in the compensated magnetic field can be detected for robust speed determination. First, high points 504 and low points 503 are detected in the course of the compensated magnetic field over time. A flank 508 in the course of the magnetic field over time is recognized by the fact that a low point 503 is followed by a high point 504 . The amplitude 507 between the low point 503 and the high point 504 must be greater than a first threshold value 505, in particular greater than an adaptive second threshold value 506. The speed can be determined by the time interval between two edges 508 . For this purpose, a time stamp is generated for each detected edge.

If a high point 504 is followed by a low point 503, no edge is detected. However, this can be an indication that the polarization of the magnet is reversed.

The detected edges 508 can then be checked for plausibility in order to check whether a detected edge 508 is plausible. In particular, if an edge 508 is greater than the first threshold value 505 but less than a second threshold value 506, the edge 508 can be checked for plausibility. If an edge 508 is identified as implausible, edge 508 is discarded and not used to determine the speed. The second adaptive threshold can be taught individually. For example, when driving, plausible complete flanks can be used to define the second adaptive threshold value. In particular, the second threshold can be increased if a specific number of edges have a greater amplitude than the second threshold.

The speed is calculated using two consecutive edges 508 for plausibility checking. If the speed is too high for the vehicle to realistically achieve, edge 508 is discarded. The faster the vehicle drives, the steeper the edges 508 are in the course of the magnetic field sensor. If the slope of edge 508 does not match the calculated velocity, edge 508 is discarded. In addition, an edge 508 can be discarded if the difference between two consecutive speeds does not match the expected acceleration of the vehicle. Furthermore, edge 508 can be discarded if, after low point 503, the first threshold value is not reached quickly enough.

6 Figure 12 shows, in schematic form, part of a vehicle according to an embodiment of the present invention.

How regarding 5 described, flanks can be detected in the compensated time profile of the magnetic field and the speed of a vehicle can be determined on the basis of this. In order to make it easier to detect edges, the compensated course of the magnetic field can be changed before the edges are detected.

In order to reduce small jumps within the compensated time profile of the magnetic field, it can first be filtered, for example with a bandpass filter.

The arrangement of the magnetic field sensor 3 can influence the compensated time profile of the magnetic field. A magnetic field sensor 3 is arranged here on a drive unit 2 in the vicinity of a wheel 4 of a vehicle (not shown). A magnet 5 is arranged on the wheel 4 . A magnetic field is generated by the magnet 5, which can be detected by the magnetic field sensor 3 when it moves past in the vicinity of the sensor. The largest signal deviation from the generated magnetic field is in the main axis 14, since the magnet is at the shortest distance from the magnetic field sensor 3 when crossing the main axis 14 and is at the same time aligned perpendicular to the main axis 14. When assembling the magnetic field sensor 3, it is possible for the drive unit 2 and thus the magnetic field sensor 3 to be arranged at an angle to the main axis 14. The magnetic field sensor 3 can measure the magnetic field in at least one measuring direction 12, preferably in two measuring directions 12, 13. If the drive unit 2 and thus the magnetic field sensor 3 are arranged rotated, the measuring directions 12 , 13 of the magnetic field sensor 3 rotate so that none of the measuring directions 12 , 13 are parallel to the main axis 14 . In this case, the usable amplitude of the magnetic field and thus the signal swing is reduced.

For this reason, the magnetic field is measured in at least two spatial directions 12, 13. Starting from the magnetic field in the two spatial directions 12, 13, the angle 15 through which the magnetic field sensor 3 is rotated can be measured. With the help of the angle 15, the values of the time profile of the compensated magnetic field measured in the two measuring directions 12, 13 can be rotated in the main axis 14, so that the usable amplitude of the magnetic field is increased. This makes it easier to recognize the flanks.

Furthermore, the magnet 5 can be arranged on the wheel 4 rotated by 180°, for example. In the case is the polarization of the magnet 5 reversed. If the magnet is not rotated by 180°, the amplitude first falls and then rises sharply. With a rotated magnet, this is reversed. In other words, in the course of the magnetic field over time, 5 to a high point 504 a low point 503. Here the polarization of the magnet can be recognized. If it is recognized that the magnet is arranged with reversed polarization, the time course of the compensated magnetic field can be inverted, so that a correct polarization of the magnet is simulated.

7 12 shows, in schematic form, a vehicle according to an embodiment of the present invention.

• - eine Steuereinrichtung 6, ausgebildet zum Betreiben der elektrischen Antriebseinheit 2 des Fahrzeugs 1 in mehreren Lastpunkten durch Verändern zumindest einer Betriebsgröße wie Stromstärke und/oder Drehzahl,
• - eine erste Ermittlungseinrichtung 8, ausgebildet zum Ermitteln eines funktionalen Zusammenhangs eines bestimmten Störmagnetfeldes mit der zumindest einen Betriebsgröße,
• - eine Messeinrichtung, umfassend den Magnetfeldsensor, welche zum Messen eines zeitlichen Verlaufs eines Magnetfelds mittels des Magnetfeldsensors 3 sowie von der zumindest einen Betriebsgröße der Antriebseinheit 2 wie einer Stromstärke der Antriebseinheit 2 und/oder einer Drehzahl der Antriebseinheit 2 ausgebildet ist,
• - eine Kompensiereinrichtung 10, ausgebildet zum Kompensieren des gemessenen zeitlichen Verlaufs des Magnetfelds anhand des funktionalen Zusammenhangs sowie der zumindest einen gemessenen Betriebsgröße der Antriebseinheit 2,
• - eine zweite Ermittlungseinrichtung 11, ausgebildet zum Ermitteln der Geschwindigkeit des Fahrzeugs 1 anhand des kompensierten zeitlichen Verlaufs des Magnetfelds und insbesondere
• - eine Bestimmungseinrichtung 7, ausgebildet zum Bestimmen des von der Antriebseinheit 2 erzeugten Störmagnetfelds, insbesondere eines durch einen Stator der Antriebseinheit 2 erzeugten Störmagnetfelds, in den mehreren Lastpunkten.

The vehicle 1 , here in the form of a pedelec, has an electric drive unit 2 , a magnetic field sensor 3 and a magnet 5 attached to a wheel 4 of the vehicle 1 . Vehicle 1 also includes:

• - a control device 6, designed to operate the electric drive unit 2 of the vehicle 1 in several load points by changing at least one operating variable such as current and / or speed,
• - a first determination device 8, designed to determine a functional relationship between a specific magnetic interference field and the at least one operating variable,
• - a measuring device, comprising the magnetic field sensor, which is designed to measure a time profile of a magnetic field by means of the magnetic field sensor 3 and the at least one operating variable of the drive unit 2 such as a current intensity of the drive unit 2 and/or a speed of the drive unit 2,
• - a compensating device 10, designed to compensate for the measured time profile of the magnetic field based on the functional relationship and the at least one measured operating variable of the drive unit 2,
• - A second determination device 11, designed to determine the speed of the vehicle 1 based on the compensated time profile of the magnetic field and in particular
• - A determination device 7, designed to determine the interfering magnetic field generated by the drive unit 2, in particular an interfering magnetic field generated by a stator of the drive unit 2, in the plurality of load points.

The determination device 7 can determine the interfering magnetic field generated by the drive unit, so that the functional relationship can be determined on this basis by means of the first determination device 8 . If the drive unit 2 has already been arranged on the vehicle with a stored functional relationship, for example a characteristic map and/or a function, the determining device 7 can be omitted.

The vehicle is designed in particular according to steps S1 to S6 1 , and the steps S1 'to S5' according to 2 to perform.

Although the present invention has been described on the basis of preferred exemplary embodiments, it is not limited thereto but can be modified in many different ways.

Claims (21)

Method for determining a functional relationship of a drive unit (2) comprising the steps: - Operating (S1) the electric drive unit (2) at several load points by changing at least one operating variable such as current and/or speed, - Determination (S2) of an interference magnetic field (304) generated by the drive unit (2), in particular an interference magnetic field (304) generated by a stator of the drive unit (2), in the plurality of load points, - Determination (S3) of a functional relationship between the specific interference magnetic field (304) and the at least one operating variable of the drive unit (2). procedure according to claim 1 , wherein the functional relationship is determined by generating at least one characteristic field of the interfering magnetic field (304) and the operating variables of the drive unit (2) such as the current strength of the drive unit (2) and/or the speed of the drive unit (2). procedure according to claim 2 , wherein at least one function is determined that approximately describes the map. Method according to one of Claims 1 - 3 , Information about the determined functional relationship, in particular the at least one function and/or the at least one characteristic diagram, being stored in the drive unit (2). Method according to one of Claims 1 - 4 , Wherein the functional connection of an amplitude (306) of the magnetic disturbance field (304) and/or a phase of the magnetic disturbance field (304) with a Current of the drive unit (2) and / or a speed of the drive unit (2) is determined. Method according to one of Claims 1 - 5 , The functional relationship, in particular in the form of a function and/or a characteristic diagram, is determined while the drive unit (2) is being operated in a vehicle (1). Method according to one of Claims 1 - 5 , The functional relationship, in particular in the form of a function and/or a characteristic map, is determined while the drive unit (2) is being operated outside of a vehicle (1). Method for checking the plausibility of a magnetic field (303) over time in a vehicle (1), in particular a single-track vehicle (1) such as a pedelec, by compensating for an interference magnetic field (304) of an electric drive unit (2) of the vehicle (1), the The vehicle (1) has a magnetic field sensor (3) and a magnet (5) arranged on a wheel (4) of the vehicle (1), with a functional relationship between a specific interfering magnetic field (304) and at least one operating variable of the drive unit (2) being the same Current and / or the speed by a method according to one of Claims 1 - 7 is determined, comprising the steps: - measuring (S4) a time profile of a magnetic field (303) by means of the magnetic field sensor (3) and of the at least one operating variable of the drive unit (2), - compensating (S5) the measured time profile of the magnetic field ( 303) based on the functional relationship and the at least one measured operating variable of the drive unit (2). procedure according to claim 8 , wherein the compensation (S5) of the measured time profile (303) of the magnetic field is based on a rotor position of the drive unit (2). Method for determining a speed of a vehicle (1), in particular a single-track vehicle (1) such as a pedelec, the vehicle (1) having an electric drive unit (2), a magnetic field sensor (3) and a sensor on a wheel (4) of the vehicle (1) arranged magnet (5), wherein a time course of a magnetic field measured by the magnetic field sensor (303) by a method according to one of Claims 8 - 9 is compensated, comprising the step of: - determining (S6) the speed of the vehicle (1) using the compensated time profile (305) of the magnetic field. procedure according to claim 10 , wherein the determination (S6) of the speed includes detecting a flank (508) over time in the measured magnetic field (303, 305). procedure according to claim 11 , wherein the detection of an edge (508) comprises the steps: - determining high and low points (503, 504) over time in the magnetic field, - determining an edge (508) based on the time sequence of a high and low point (503, 504), and - comparing the amplitude (507) of the determined edge (508) with at least one threshold value (505), the determined edge (508) being considered recognized if the amplitude (507) of the determined edge (508) is greater than a first smaller threshold value (505) and/or greater than a second larger adaptive threshold value (506). Method according to one of Claims 11 - 12 , with the values of the measured magnetic field (303, 305) being processed, in particular filtered, before the edge (508) is detected, preferably by means of a bandpass filter, with in particular a stop and pass range of the bandpass filter being adjusted to a predetermined rotational frequency of the wheel of the vehicle ( 1) is adjusted. Method according to one of Claims 11 - 13 , wherein a time stamp is generated and/or a counter is increased when an edge (508) is detected. Method according to one of Claims 11 - 14 , wherein the magnetic field is measured in at least two spatial directions (12, 13) and wherein the values of the magnetic field (303, 305) measured in at least two spatial directions (12, 13) before detecting a flank (508) in a main axis (14) of the magnetic fields are rotated, in particular the angle (15) of the main axis (14) for the rotation being determined on the basis of values of the magnetic field (303, 305) in a second spatial direction (13). Method according to one of Claims 11 - 15 , wherein a time profile of a vector of the magnetic field (303, 305) is also evaluated to evaluate the rising and/or falling edges (508), in particular to check their plausibility. Method according to one of Claims 11 - 16 , a possible speed being calculated on the basis of the determined edge (508) and the edge (508) being checked for plausibility based on at least one of the following conditions using a plausibility check method: - If the possible speed is above a definable threshold value, the determined edge (508 ) discarded. - If the gradient of the determined edge (508) is below a threshold value, the determined edge (508) is discarded. - If the time difference between the low point (503) of the determined edge (508) and the time when a threshold value (505) is exceeded in the edge profile is above a predeterminable threshold value, the determined edge (508) is discarded. - If the vehicle accelerations, calculated from a currently determined edge (508) and an earlier edge, are above a predefinable threshold value, the currently determined edge (508) is discarded. procedure according to Claim 17 , wherein the plausibility method includes an edge prediction, in particular based on acceleration data of the vehicle (1), so that a detected edge (508) is rejected as implausible if no edge (508) is predicted based on the acceleration data. Method according to one of Claims 11 - 18 , wherein a predefinable number of determined edges (508) and in particular an angular profile of the magnetic field vector is determined to detect the polarization of the magnet (5), the polarization being determined based on a comparison of the maximum amplitude (507) of the rising and the falling amplitude, where if the maximum falling amplitude is greater than the maximum rising amplitude, the polarization of the magnet (5) is assumed to be reversed and the measured values of the magnetic field are inverted, the polarization being based in particular on a predeterminable number of rising and/or falling edges (508) is evaluated. Vehicle (1), in particular a single-track vehicle (1) such as a pedelec, the vehicle (1) having an electric drive unit (2), a magnetic field sensor (3) and a magnet (5 ) comprising: - a control device (6), designed to operate the electric drive unit (2) of the vehicle (1) at several load points by changing at least one operating variable such as current and/or speed, - a first determination device (8), designed to determine a functional relationship between a specific interference magnetic field (304) and the at least one operating variable, - a measuring device, comprising the magnetic field sensor, which is used to measure a time profile of a magnetic field (303) by means of the magnetic field sensor (3) and the at least one operating variable of the drive unit (2), such as a current intensity of the drive unit (2) and/or a speed of the drive unit (2) is formed, - a compensation device (10), designed to compensate for the measured time profile of the magnetic field based on the functional relationship and the at least one measured operating variable of the drive unit (2), - A second determination device (11), designed to determine the speed of the vehicle (1) based on the compensated time profile (305) of the magnetic field and in particular - a determination device (7) designed to determine the interfering magnetic field (304) generated by the drive unit (2), in particular a interfering magnetic field (304) generated by a stator of the drive unit (2), in the plurality of load points. Vehicle (1) according to claim 20 , wherein the first determination device (8) is designed to determine the functional relationship from a memory of the vehicle (1), in particular a memory of the drive unit (2).

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