Method for controlling an electric motor of a drive system

Abstract

The invention relates to a method for controlling an electric motor of a drive system of an electric drive, comprising the steps of: obtaining sensor data indicative of a rotational speed; determining at least one rotational speed gradient on the basis of the sensor data; determining a state of change of an output component driven by the drive system, on the basis of the at least one rotational speed gradient; adapting, in the state of change, a rotational speed of the electric motor on the basis of the at least one rotational speed gradient.

Description

[0001] Method for controlling an electric motor of a drive system

[0002] Technical field

[0003] The present invention relates to a method for controlling an electric motor of a drive system of an electric drive, a method for determining a cumulative component load of at least one component of a drive system of an electric drive, a control unit and an electrically powered means of transport.

[0004] State of the art

[0005] It is known from the prior art that electric motors rotate with low torque and high speed, so a gearbox is necessary to translate the torque and speed to the wheel in a usable way.

[0006] Generally, every moving component, especially a rotating one, exhibits inertia. In electric vehicles, this includes, in particular, the shaft, the rotor, and the rotating components of the transmission. A change in rotational speed results in an acting moment of inertia in these components. This inertia is component- and / or system-specific.

[0007] A method for electric vehicles is known from the prior art in which component stresses caused by drive-side torque fluctuations are detected and monitored. For this purpose, the rotational speed of the electric vehicle's drivetrain is monitored to assess the impact on component durability at high speed gradients.

[0008] Description of the invention

[0009] A first aspect concerns a method for controlling an electric motor in a drive system or electric drive. This method can be either a motor control method or a motor regulation method. Regulation is a dynamic process involving continuous measurement and adjustment. This could, for example, be a comparison of an actual value with a target value. Control, on the other hand, is the setting of a specific value that is adjusted independently of continuous measurements or adjustments.

[0010] An electric drive can be integrated into an electrically powered means of transport and serves to provide electrical energy. This includes vehicles with additional muscle power, such as bicycles, tricycles, tandems, unicycles, and similar means of transportation, or alternatives that no longer rely on muscle power due to the use of the electric drive. In particular, the electric drive can be the electric drive of an e-bike or pedelec. Alternatively, purely electrically powered motor vehicles, such as passenger cars, motorcycles, trucks, and similar vehicles, are also conceivable. Application in a hybrid vehicle is also possible. The electric drive can include a control system that regulates the drive system.

[0011] An electric motor is a device that converts electrical energy into mechanical energy. This occurs through the interaction of magnetic fields generated by the flow of current in coils of electrically conductive wires. An electric motor typically consists of a fixed magnetic component and a moving component. The fixed magnetic component can be a stator, and the moving component can be a rotor. The moving component is influenced by the magnetic field of the fixed magnetic component and rotates, thereby generating mechanical work. Electric motors are highly efficient, powerful, and versatile. For example, an electric motor can be an asynchronous motor, a synchronous motor, a DC motor, an induction motor, or a geared motor.

[0012] A drive system is a device used to transmit rotational forces from an electric motor to a driven output component. The drive system can, for example, be a drive train with a gearbox. The gearbox can be a reduction gearbox. A reduction gearbox can be a spur gearbox, a planetary gearbox, or a wave gearbox. A reduction gearbox may be necessary to convert the torque characteristics of the electric drive into a usable output for the driven component by means of the gear ratio. A drive system can comprise several gearboxes, in particular several different types of gearboxes. In general, any gearbox that can provide a usable reduction in the rotational speed of the electric drive on the output side is conceivable. It is possible to connect the drive system with other transmission elements.For example, flexible coupling or freewheel elements are conceivable as transmission elements in power transmission.

[0013] Furthermore, it is conceivable that the drive system includes a differential. By selecting the drive system, drive-specific characteristics are known, such as the overall gear ratio between the input and output sides, in particular the overall gear ratio of the transmission, as well as the individual gear ratios of individual gear stages. A gear stage can comprise, for example, gears, belts, and / or chains. The individual gear ratios of the individual gear stages result in the overall gear ratio of the transmission.

[0014] The term "drive-side" refers to the side from which the driving force or energy is introduced into the system. Typically, this is the side where the motor or main power source is located. For example, in a vehicle, the motor is drive-side because it provides the energy to propel the vehicle.

[0015] "Output side" refers to the side where the effects or result of the driving force occur. It is the side where the work is done by the system, or the side that provides the output. In the context of a vehicle, the wheels would be the output side, as they utilize the energy to move the vehicle forward.

[0016] The process includes the step: obtaining sensor data, where the sensor data indicates a rotational speed.

[0017] Receiving sensor data can include, for example, receiving a digitized sensor signal. The digitized sensor signal can be a direct sensor signal that is digitized before being received. Receiving sensor data that is stored in a readable format in a database or other storage medium is also conceivable. Receiving sensor data from multiple sensors is also possible.

[0018] For example, the sensor data can include data from a sensor that detects a signal on the output side, input side, and / or within the power transmission system. The detected signal can be a rotational speed. The sensor data indicates a rotational speed. In particular, sensor data from a rotational speed sensor is conceivable for this purpose. Sensor data that allows for inferences about the rotational speed is also conceivable. This includes, in particular, acceleration data, position data, and / or torque data. Rotational speed is understood as the velocity or revolutions per unit of time of a rotating object. Specifically, rotational speed can also be the rate of rotation.

[0019] The procedure includes the further step of determining at least one rotational speed gradient based on the sensor data.

[0020] The at least one rotational speed gradient can be understood as a change over time of at least one rotational speed or at least one rotational velocity of a rotating object. An increasing rotational speed can be understood as a positive rotational speed gradient, and a decreasing rotational speed as a negative rotational speed gradient. Alternatively, the opposite understanding of positive and negative rotational speed gradients is also conceivable. For the following explanations, the understanding of the terms described above will be used. In the case of a different understanding, a person skilled in the art will be able to adapt the teaching accordingly. The at least one rotational speed gradient can be zero. This means that the rotational speed does not change, and consequently, the object rotates at a constant speed or remains stationary.

[0021] Based on the at least one speed gradient and the known, system-specific transmission ratios, the speed of each component, in particular each rotating component, of the drive system can be determined.

[0022] The procedure includes the further step of determining a change state of an output component driven by the drive system, based on the at least one speed gradient. A change state is defined as any event in which the at least one speed gradient initially changes on the output side. This means that the at least one speed gradient can be triggered and / or maintained by an output-side condition that does not result from a torque of the drive system. In the change state, the at least one speed gradient can counteract the rotational speed of at least one component of the drive system. A negative speed gradient can indicate that the output component is being decelerated by internal or external influences.Internal influences can be those occurring within the output component, such as service braking through a braking system that slows down the output component, or friction within the braking system. External influences can be those occurring outside the output component, such as driving resistance or the specific characteristics of a surface. Generally, a change state can encompass any time interval. The output-side speed gradient can be constant and / or fluctuating over this period. The change state can persist as long as the output-side speed gradient opposes the speed of at least one component of the drive system. For example, the change state can persist until the output component is no longer actively braked.The change state can be terminated when the drive and driven sides rotate again at synchronous or nearly synchronous speeds, or when the drive and driven sides have come to a standstill.

[0023] A driven component is understood to be any component arranged on the output side that can lead to a change in the rotational speed of the output side, i.e., a change state. The driven component can be a system of driven components. In particular, the driven component can include a wheel and / or a component of a braking system, especially a brake disc. The driven component can, in particular, be a wheel comprising a braking system. It is understood that the method is not limited to determining the change state of a driven component. The method can, for example, be applied in parallel to each driven wheel of an electrically powered means of transport. The method includes the further step of: adjusting, in the change state, a

[0024] Speed ​​of the electric motor, based on at least one speed gradient.

[0025] The rotational speed of an electric motor can be the rotational speed of the rotor of the moving component of the electric motor, in particular the rotor itself. The rotational speed can be detected by a sensor on the drive side. This sensor enables the determination of the electric motor's rotational speed. Direct or indirect determination is possible. Direct determination can be achieved, for example, using a speed sensor. Indirect determination is possible, for example, using a Hall effect sensor, ultrasonic sensor, accelerometer, wheel speed sensor, inductive sensor, optical sensor, and / or encoder. Indirect determination can also be achieved using electric motor-specific parameters. These parameters can include, for example, voltage, frequency, load current, motor characteristics, and / or a drive signal.The motor characteristics can consist of one or more characteristic curves that show a relationship between rotational speed and other parameters such as torque or power. The drive signal can be a PWM signal (pulse width modulation signal). Multiple sensors for directly or indirectly determining the electric motor's rotational speed are also conceivable. It is also possible to use several identical sensors.

[0026] Adjusting the speed of the electric motor can involve adjusting its speed according to at least one speed gradient. This adapts the torque of the at least one component to the at least one speed gradient. For example, when decelerating the drive component, a negative speed gradient may be encountered, so adjusting the speed of the electric motor involves reducing its speed. The output component may rotate at a different speed than the electric motor's rotor or other drive system components due to the gear ratios within the drive system. As described above, the overall gear ratio, encompassing the individual gear ratios, allows for the determination of the speed of the rotating components of the drive system.

[0027] Accordingly, by determining the at least one speed gradient, the rotational speeds of the drive system components, up to and including the rotor speed, can be determined. Adjusting the electric motor's speed, viewed vectorially, follows the same direction as the at least one speed gradient. This makes it possible to reduce the torque of the drive system components, particularly the rotor. Consequently, the mechanical stresses on the drive system components caused by the output-side induced torque, resulting from the at least one speed gradient, can be reduced. This reduction can be minimized to improve the durability of the electric drive.

[0028] Adjusting the speed of an electric motor can be done actively or passively. Passive adjustment can involve switching the electric motor off. Active adjustment can involve actively controlling the speed of the electric motor. The specific type of active control depends on the type of electric motor. Active control can also include actively braking.

[0029] This method enables the detection of a change state induced by a change in the rotational speed of the output component driven by the drive system. This allows the electric motor's rotational speed to be precisely adjusted to reduce the damaging effects of a rotational speed change on the drive system components, including the rotor. This mitigates torque peaks on the rotating components, potentially reducing material requirements for these components, thereby lowering costs and / or weight. Furthermore, it improves the durability of the electric drive. Implementing this method requires no additional installation space, as existing components can be used. This allows for an improved design-to-cost and / or design-to-weight ratio.

[0030] According to one embodiment, adjusting the rotational speed is a reduction in rotational speed.

[0031] Reducing the speed of the electric motor can be proportional to the change in speed, i.e., to at least one speed gradient. This means that, taking into account the gear ratios of the drive system, the electric motor's speed can be adjusted proportionally to at least one speed gradient. This can reduce the torque and minimize the potential for damage caused by the speed gradient. The reduction can also be disproportionately or inversely proportional to the speed gradient. Reducing the speed will at least lead to a reduction in the potential for damage. The degree of reduction is significantly influenced by the accuracy of the speed adjustment.

[0032] In one embodiment, adjusting the speed includes actively braking the electric motor.

[0033] Active braking can involve actively energizing the electric motor. Possible methods for active braking include voltage control, current control, frequency control, pulse width modulation control, field weakening control, or sensorless control.

[0034] In another embodiment, the speed of the electric motor is adjusted in such a way that the load within the drive system caused by the at least one speed gradient is minimized.

[0035] This is intended to reduce the stress on the drive system components caused by the at least one speed gradient. The at least one speed gradient leads to a torque peak within the rotating components of the drive system, as the components cannot follow the change in speed due to their moment of inertia. Therefore, the speed of the electric motor should be adjusted to minimize, in particular, the mechanical stress within the drive system induced by the at least one speed gradient. This can be achieved by adjusting the speed proportionally to the at least one speed gradient and taking into account the overall gear ratio of the drive system.

[0036] In one embodiment, the sensor data includes the rotational speed of the output component driven by the drive system. Regardless of the cause of a change state, a change in the rotational speed of the driven output component is a consequence of the existence of a change state. This means a deceleration of the output component that is not caused by the drive side. The rotational speed of the output component driven by the drive system can be used to determine the at least one rotational speed gradient. This allows for the direct determination of the at least one rotational speed gradient. Since an output component driven by the drive system is the cause of the rotational speed change, it is conceivable to use the data from a sensor that detects the rotational speed of the output component driven by the drive system. Alternatively, sensor data from a sensor that detects a rotational speed on the drive side can also be used.A drive-side speed can be the speed of the electric drive, in particular the speed of the electric motor of the electric drive. The drive-side speed can include one or more further processing steps to obtain the at least one speed gradient on which the determination of the at least one torque is based. The data from both sensors can be used, as this creates redundancy in the sensor data. The redundancy can also be created by using two sensors on either the drive or driven side. All these embodiments can additionally reduce the influence of undetected sensor drift. Furthermore, the use of drive-side and driven-side sensor data enables a detailed analysis of the effects of the changing conditions, for example, through correlation analyses.This allows, for example, the recording of how the output-side and input-side sensor data differ in various ways.

[0037] Change states, triggered by the identical wear component, change over time. This can enable the early detection of component damage.

[0038] In one embodiment, the driven output component is a wheel.

[0039] The wheel can be in contact with the ground via a tire and therefore significantly influence the output speed. Simultaneously, the wheel can present a relatively large surface area to the influence of rolling resistance and be directly connected to the braking system. Changes in the wheel's output speed can result from altered ground conditions, such as uneven or muddy surfaces. The wheel may incorporate a braking system. Active braking or slippage of the braking system can reduce the wheel's speed and consequently lead to the detection of a change in the wheel's rotational speed.

[0040] In one embodiment, the electric drive is a drive for an electrically powered bicycle.

[0041] As described above, an electrically powered bicycle can be any bicycle equipped with an electric drive system designed to propel the bicycle. This can specifically include e-bikes or pedelecs.

[0042] In one embodiment, the method comprises the further step of determining, in the changing state, at least one torque at at least one component of the drive system, based on the at least one speed gradient, at least one moment of inertia and the adjustment of the speed.

[0043] The torque at least one of the components of a drive system can be understood as a force or rotational force. It can be a vector quantity that describes the effect of a force on the rotational motion of a rigid body around a specific point. The torque of a motor, especially an electric motor, can describe its ability to generate rotational motion and move a load. Torque is based on the moment of inertia and an angular acceleration. The angular acceleration is based on a change in rotational speed over time, i.e., a speed gradient. The angular acceleration can be determined based on the at least one speed gradient, adjusting the speed of the electric motor, and the known gear ratios of the drive system. This allows the angular acceleration to be determined for one, a multitude, or all components of the drive system.In this case, the moment of inertia can encompass the moment of inertia of at least one component of the drive system. The moment of inertia can encompass a multitude of moments of inertia from a multitude of components of the drive system. The moment of inertia can also encompass the moments of inertia of all components of the drive system, particularly the rotating components. The number of moments of inertia used depends on the selection of the drive system components under consideration. In other words, a moment of inertia can exist for each of the at least one components of the assembly. The moment of inertia of the at least one component of the drive system is component- and / or system-specific and known. For this purpose, the dimensions and mass of the at least one component can be known. In particular, the moment of inertia of all components of the drive system can be known.The moment of inertia of at least one component can, for example, be stored in a database.

[0044] Determining the at least one torque in the state of change can be a discrete calculation of the at least one torque per time point or a torque acting on average over the state of change.

[0045] The procedure includes the further step of determining at least one load value of the at least one component of the drive system for the change state, based on the at least one torque.

[0046] A load value can be understood as at least one value that describes at least one load on at least one component of the drive system for the change state. This load value can describe the magnitude and duration of the torque applied to the component during the change state. The nature of the change state can influence the mechanical load on the component and thus its durability. For example, gentle braking of the wheel can result in a lower mechanical load on the component than, for example, emergency braking.Similarly, the degree of unevenness in a substrate can also influence the mechanical load and, with increasing unevenness, lead to a greater mechanical load on the at least one component, as this results in abrupt changes in rotational speed and thus higher torque peaks in the at least one component of the drive system. The at least one load value can depend on the determination of the at least one torque. Consequently, the at least one load value can be averaged over the time interval of the change state. A multitude of discrete, at least one load value over the duration of the change state is also conceivable. The at least one load value for the at least one component can encompass at least one load value for a multitude of components or all components of the drive system.The at least one load value may be a single value representative of the overall state of the drive system. Alternatively, the at least one load value may be a separate value for any number of components. Specifically, the at least one load value can be a separate value for all components of the drive system, particularly all rotating components. This allows for a comprehensive assessment of the mechanical load on each individual component of the drive system. For example, characteristic values ​​may be stored to determine the at least one load value. It is conceivable that these characteristic values ​​are stored in a lookup table.

[0047] This method enables the detection of a change state induced by a change in the rotational speed of the driven component of the drive system. This allows for the detection of stresses during the change state on at least one component of the drive system and the identification of mechanical damage. This, in turn, allows for the early implementation of maintenance measures to prevent or at least minimize consequential damage.

[0048] In other words, for example, a speed gradient induced by the output side can occur when a wheel brakes. The components of the drive system may exhibit torque due to this input-induced rotation, preventing them from immediately following the change in output speed. The resulting load situations, particularly torque peaks, can exceed normal operating conditions and lead to mechanical overloads, causing component damage. Since each of these regular mechanical overloads has a damaging effect on the individual components, it is important to be able to at least estimate the loads that each component of the drive system experiences over time.The transmission may be designed to translate the high engine speed to a usable output speed, meaning the transmission components can be subjected to particularly high mechanical stress under the described load case. The present method makes it possible, for example, to detect these stresses on the transmission components, which are caused by the braking of the output component, such as a wheel. Furthermore, this improves driver safety, as damage to the components can be detected early, preventing consequential damage to the components and the driver. No additional installation space is required for the implementation of this method, as existing components can be used. This allows for an improved design-to-cost and / or design-to-weight ratio.

[0049] Another aspect is a method for determining at least one component load of at least one component of a drive system of an electric drive.

[0050] The component load can be a value that is representative of the stress on at least one component with respect to a change state. The component load can indicate how strongly the at least one component is stressed by the change state.

[0051] The procedure includes the step: Determining at least one load value using a procedure described above.

[0052] The procedure includes the further step: classifying the at least one load value of the at least one component.

[0053] As described above, the type of change state, i.e., the magnitude and duration of the application of at least one torque to at least one component, influences the at least one load value. The type of change state can therefore lead to different classifications, with the classification depending on the at least one load value of the at least one component. The classification can be a value that reflects the nature of the change state. The classification can also depend on the at least one component. For example, an identical load value on different components can result in different classifications due to the different components. Conversely, an identical load value on different components can result in the same classification.For example, key values ​​can be stored to classify at least one load value. It is conceivable that these key values ​​are stored in a lookup table.

[0054] The procedure includes the further step: determining at least one component load of the at least one component, based on the classification of the at least one load value of the at least one component.

[0055] In addition to classifying the at least one load value, further values ​​can be considered for determining the at least one component load. Determining the at least one component load can be based solely on the classification of the at least one load value.

[0056] In order to determine the influence of the change state on the durability of the at least one component, at least one component load is determined based on the classification of the at least one load value of the at least one component.

[0057] This step serves to classify the change states and assess the change state in relation to the mechanical stress on the at least one component. This enables an estimation of the durability of the at least one component.

[0058] Analogous to the descriptions of the independent method claim, the determination of the at least one component load can be performed dynamically. The determination of the at least one

[0059] Component loading cannot be performed in real time, but at a later time.

[0060] The procedure may include the further step of determining a cumulative component load of the at least one component based on the classification of the at least one load value and at least one further load value of the at least one component for a different change state.

[0061] Each change state influences at least one component load. Therefore, not only the singular classification of a single change state and the resulting at least one component load are of interest, but also the influence of cumulative change states and thus cumulative component loads. For this purpose, at least two load values ​​can be accumulated to determine a cumulative classification and consequently a cumulative component load for the at least one component in the change state. As an intermediate step, the individual component loads for each change state of the at least one component can be determined and then accumulated to calculate the cumulative component load.In this context, the frequency of occurrence of a change state can also be taken into account. This leads to an improved assessment of the service life of the at least one component. A singular change state with a comparatively large torque on the at least one component of the drive system can mean less or more mechanical stress for at least this component of the drive system than a multitude of change states with a comparatively small torque.

[0062] The determined values ​​for a change state, specifically the sensor data, at least one speed gradient, at least one torque, at least one load value, the classification, and at least one component load, can be further processed after determination. This further processing can include, in particular, storing the values ​​on a storage medium. The storage medium can be located within the electrically powered vehicle. Further processing can also include storing the values ​​in a cloud or on another storage unit located outside the electrically powered vehicle, for example, in a physical data center, for instance, via a wireless connection, in particular a radio connection or a WLAN connection.This allows access to the determined values ​​at any given time and is particularly useful for the cumulative analysis of component loads. Storing the data in a cloud or other physical data center enables, for example, a comparison of identical and / or different components of the drive system across different drive systems. This allows for the identification of systematic changes and their effects, as well as drive system-specific or output system-specific changes and effects. Further processing can also include displaying or outputting the values. This allows for the monitoring of at least one component load, particularly through display on a screen.

[0063] In one embodiment, the process is carried out repeatedly.

[0064] The repeatability of the execution is relevant for the continuous recording and determination of the change states and their effects, in particular the at least one load and the at least one component load of the at least one component. This enables, above all, a dynamic, i.e., continuous and real-time, determination of the at least one load and the at least one cumulative component load of the at least one component.

[0065] Another aspect concerns a control unit configured to execute a procedure according to the embodiments described above.

[0066] Advantages and features described with respect to the method also apply to the control unit and vice versa. These are therefore described only once. The same applies to an electrically powered means of transport comprising a drive system comprising an electric motor, a battery, and a drivetrain, at least one output component, at least one sensor, and a control unit described above, wherein the drive system is configured to drive the at least one output component via the electric motor through the drivetrain, wherein the at least one sensor detects a rotational speed, and the control unit is communicatively connected to the at least one sensor and the drive system.

[0067] Brief description of the characters

[0068] Figure 1 shows an electrically powered means of transport and

[0069] Figure 2 shows a flowchart of a process.

[0070] Detailed description of embodiments

[0071] Figure 1 shows an electrically powered means of transport 6. The means of transport is a pedelec β, comprising a drive system 1, including an electric motor 7, a battery 8, and a drive train 9, a driven component 2 in the form of a wheel 2, comprising a braking system (not shown), two sensors 10, and a control unit 5. The drive system 1 can drive the wheel 2 by means of the electric motor 7 via the drive train 9. The drive train 9 includes a reduction gear 3. The first sensor 10 detects a rotational speed on the drive side, and the second sensor 11 detects a rotational speed on the driven side. The control unit 5 is communicatively connected to the two sensors 10 and 11 and the drive system 1. The reduction gear 5 includes a gear reduction stage, the gear reduction being effected by the engagement of two gears 4.

[0072] The electrically powered transport vehicle 6 moves at a constant speed.

[0073] Speed. The electric motor 7 drives the drive train 9 at a constant speed. The electric motor 7 has a high but constant speed. The reduction gear 3 reduces the speed via the gear stage using the gears 4 to a constant speed usable for driving the wheel 3.

[0074] The electric motor 7 sets the rotor of the electric motor 7, shafts 12, the gears 4 within the reduction gear 3, and the wheel 2 into rotation. Although there are different rotational speeds within the drive system 1, the respective rotational speeds are constant. In other words, the rotational speed gradient corresponds to the value zero.

[0075] Figure 2 shows a flowchart of an exemplary procedure.

[0076] When braking is initiated by the braking system through contact of brake pads against a brake disc, the rotational speed of wheel 2 is reduced. The second sensor 11 detects the rotational speed of wheel 3 as a digital signal and provides this to the control unit 5 in the form of sensor data. In step S1, the control unit 5 receives the data detected by sensor 11 and, in step S2, determines a rotational speed gradient of wheel 2 based on this data. The rotational speed gradient is the change in rotational speed over time.

[0077] In step S3, the control unit 5 determines a change state of wheel 2, driven by drive system 1, based on the speed gradient. Since a braking process is taking place and the speed is decreasing, a negative speed gradient of wheel 2 is determined. From this, the presence of a change state is determined.

[0078] As described above, the drive system 1 comprises a number of rotating components. Reducing the rotational speed of the wheel 2 results in mechanical loads in the gear mesh of the gears 4 within the reduction gear 3, the shafts 12, and the rotor, since these components each exhibit a moment of inertia due to their rotation. The moment of inertia of the individual components of the drive system 1 is known, as the mass and dimensions of each component are known.

[0079] To reduce the torque of the components and thus minimize the load within the drive system 1 caused by the at least one speed gradient, the speed of the electric motor 7 is adjusted in step S4, based on the at least one speed gradient. Braking results in a negative speed gradient, so adjusting the speed of the electric motor 7 by active braking leads to a reduction in speed. This reduction in speed decreases the angular acceleration of the individual components and thus the torque.

[0080] This reduces the damaging effects on the components of the drive system 1 caused by the braking of wheel 2. The degree of reduction in these effects is determined by the accuracy of the active braking of the electric motor 7. If the active braking is proportional to the speed gradient of wheel 2, taking into account the gear ratio of the drive system 1, the damaging effect on the components is minimal. This requires rapid detection by sensors 10 and 11, processing by the control unit 5, and rapid speed control.

[0081] During the change state, the torque for each component of drive system 1 is determined in step S5, based on the speed gradient, the moment of inertia of the respective component, and the adjustment of the speed. The moments of inertia of the individual components are determined based on their mass and dimensions and are known.

[0082] In step S6, the control unit 5 determines a load value for each component of the drive system 1 based on the torques at the components. For this purpose, the rotational speed, the speed gradient, and thus the torque are determined for each component of the drive system based on the known gear ratio and the output-side speed gradient. Taking into account the mass and dimensions of each component, the respective moment of inertia of the component, and consequently the load value for each component of the drive system, can be determined.

[0083] The change state persists as long as the braking continues. In other words, once the brake pads release from the brake disc, the change state ceases. In step S7, following the determination of the load values ​​of the drive system 1 components, control unit 5 determines the classifications of these load values ​​and then, in step S8, calculates a component load for each component, based at least on the classification of the load values ​​of the drive system 1 components.

[0084] If further deceleration is detected by the output-side speed sensor 11, another change state occurs, and the control unit 5 repeats steps S1 to S8. This allows different load values ​​of the components to be recorded for different change states. In step S9, this enables the determination of a cumulative component load based on the classifications of the load values ​​for different change states. Steps S1 to S9 are also repeated to record and accumulate the component load for further change states.

[0085] This process occurs continuously and in real time, so that the component load is accumulated with each further change state of the already determined component load, making real-time monitoring of the component load of each component of the drive system possible.

[0086] Reference mark

[0087] drive system

[0088] Output component; wheel

[0089] Gearbox, reduction gearbox

[0090] gear

[0091] control unit

[0092] Means of transport, e-bike

[0093] electric motor

[0094] battery

[0095] Powertrain

[0096] Sensor on the drive side

[0097] Output side sensor

[0098] Wave

[0099] Receiving sensor data

[0100] Determining at least one speed gradient

[0101] Determining a state of change

[0102] Adjusting a speed

[0103] Determining at least one torque

[0104] Determine at least one load value; classify at least one load value; determine at least one component load; determine a cumulative component load

Claims

Patent claims 1. Method for controlling an electric motor of a drive system (1 ) of an electric drive, comprising the steps: Receiving sensor data (S1) where the sensor data indicate a rotational speed; Determining at least one speed gradient (S2) based on the sensor data; Determining a change state (S3) of an output component (2) driven by the drive system (1), based on the at least one speed gradient; Adjusting, in the state of change, a speed (S4) of the electric motor (7), based on the at least one speed gradient.

2. Method according to claim 1, wherein adjusting the rotational speed is a reduction in rotational speed.

3. Method according to one of the preceding claims, wherein adjusting the speed comprises actively braking the electric motor (7).

4. Method according to one of claims 1 or 2, wherein adjusting the speed includes switching off the electric motor (7).

5. Method according to any one of claims 1 to 3, wherein the speed of the electric motor (7) is adjusted in such a way that the load within the drive system (1) caused by the at least one speed gradient is minimized.

6. Method according to one of the preceding claims, wherein the sensor data includes the rotational speed of the output component (3) driven by the drive system (1).

7. Method according to one of the preceding claims, wherein the driven output component (2) is a wheel (2) driven by the drive system.

8. Method according to one of the preceding claims, wherein the electric drive is a drive of an electrically powered bicycle (6).

9. A method according to any of the preceding claims, comprising the steps of: determining, in the changing state, at least one torque (S5) at at least one component of the drive system (1), based on the at least one speed gradient, at least one moment of inertia and the adjustment of the speed; and Determining at least one load value (S6) of the at least one component of the drive system (1 ) for the change state, based on the at least one torque.

10. Method for determining at least one component load of at least one component of a drive system (1 ) of an electric drive, comprising the steps: Determining at least one load value (S6) using a method according to claim 9; Classifying the at least one load value (S7) of the at least one component; and Determining at least one component load (S8) of the at least one component, based on the classification of the at least one load value of the at least one component.

11. Control unit (5), configured to perform a method according to one of the preceding claims.

12. Electrically powered means of transport (6) comprising a drive system (1) comprising an electric motor (7), a battery (8), and a drive train (9), at least one output component (2), at least one sensor (10, 11), and a control unit (5) according to claim 11, wherein the drive system (1) is configured to provide at least one The output component (2) is driven by means of the electric motor (7) via the drive train (9), wherein the at least one sensor (10,11) detects a rotational speed, and the control unit (5) is communicatively connected to the at least one sensor (10,11) and the drive system (1).

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