Method for open-loop control of an electric drive motor of an electric motor-driven vehicle, and vehicle

Abstract

The invention relates to a method for the open-loop control of an electric drive motor (4) of an electric motor-driven vehicle (2), in particular a two-wheeled vehicle, for anti-slip closed-loop control, wherein a present request (Ir) for a motor parameter, in particular for a motor current, is output by an open-loop control unit (14) integrated in a closed-loop control circuit (8) for controlling the drive motor (4), the drive motor (4) is monitored with regard to an overspeed (Se) and, in the event of the detection of an overspeed (Se), intervention is made in the closed-loop control circuit (8) of the drive motor (4) and the present request (Ir) is corrected, such that a corrected request (Ic) is obtained which is used for controlling the drive motor (4).

Description

[0001] Page 1

[0002] 2024439 WO

[0003] Method for controlling an electric drive motor of an electrically powered vehicle and vehicle

[0004] The invention relates to a method for controlling an electric drive motor of an electrically powered vehicle, in particular a two-wheeled vehicle, specifically for traction control. The invention further relates to such an electrically powered vehicle, in particular a two-wheeled vehicle such as an electrically powered motorcycle or scooter, equipped with traction control.

[0005] Anti-slip systems (ASR), also known as traction control, are standard in passenger cars. They are increasingly being used in two-wheeled vehicles as well.

[0006] For such an anti-slip control system, the speed of a wheel is regularly determined via a wheel sensor and compared, for example, with the motor speed of the drive motor; if there is a deviation, the drive motor is adjusted accordingly.

[0007] This involves a certain amount of effort, especially with regard to the required sensors, which leads to increased costs.

[0008] For two-wheeled vehicles, especially e-bikes, traction control is of particular importance for driving safety. For example, wheel spin when the vehicle is leaning and / or on loose or slippery surfaces often leads to a critical driving situation. Page 2 Another problem with two-wheeled vehicles arises in driving situations where the drive wheel lifts off the ground, for example, when jumping off-road, on uneven roads, or over bumps or speed bumps. Upon landing, this causes a short-term load spike, which can lead to high, temporary current peaks for the drive motor.

[0009] Based on this, the invention aims to enable a cost-effective traction control system for a vehicle, in particular a two-wheeled vehicle.

[0010] The problem is solved according to the invention by a method for controlling an electric drive motor of an electrically powered vehicle, in particular a two-wheeled vehicle. The control of the electric drive motor is also carried out, in particular, with regard to traction control, in order to at least limit wheel spin of the vehicle. The drive motor is the drive motor of a vehicle drive system.

[0011] The electric drive motor is generally controlled by a motor controller. This controller has a closed-loop system for controlling the drive motor, with an integrated control unit that, during operation, outputs an instantaneous request for a motor parameter, specifically for a motor current. The control loop is primarily a current control loop. The integrated control unit is specifically designed for field-oriented control; that is, the drive motor is controlled in a manner known per se via field-oriented control. The fundamental control of the drive motor depending on different requirements is generally known.

[0012] With regard to the anti-slip control, the drive motor is monitored for overspeed and in the event of overspeed detection, i.e. if, for example, a target speed deviates from an actual speed, the control loop is intervened and the current requirement, specifically the current requirement, is corrected so that a corrected requirement is obtained, which is then used for controlling the electric drive motor.

[0013] The task is further solved by an electrically powered vehicle, in particular a two-wheeled vehicle, especially an electrically powered motorcycle or scooter, which has a motor control system designed and equipped to carry out the aforementioned steps.

[0014] Furthermore, the problem is solved by a computer program according to claim 13. When the computer program is executed by a computer, the steps described in detail below are initiated. For this purpose, the computer program is, for example, uploaded to an engine control unit and then causes the vehicle to execute the following steps during operation.

[0015] A particular advantage of the present invention is that the drive motor is monitored for overspeed and then the motor control is adjusted to correct, and in particular reduce, the current requested by the control unit integrated in the control loop.

[0016] A key aspect here is that the actual control system, specifically the field-oriented control, is not directly interfered with. Rather, it is an additional control intervention that is only triggered when overspeed is detected. This control intervention, and thus the traction control, can preferably be deactivated by default.

[0017] In this context, "requirement" generally refers to the specification of a value for a defined motor parameter, particularly the motor current. "Correction of requirement" accordingly refers to a correction of this value, and the corrected requirement is the correspondingly corrected value. Page 4

[0018] By correcting the requirement, in particular by reducing the requirement, the drive motor is ultimately operated with a lower motor current in the event of a detected overspeed, thus achieving effective anti-slip control and reducing the risk of a drive wheel spinning.

[0019] In a preferred embodiment, overspeed is determined based on a parameter of the drive motor, in particular based on the rotational speed of the drive motor, and specifically based on the rotational speed of the rotor. For example, overspeed is detected when a determined instantaneous rotational speed exceeds an instantaneous target speed and / or a predefined limit. The conditions and / or values ​​of the parameter used to detect overspeed are stored, for example, depending on different road conditions and / or determined in advance, for example, through tests. The corresponding values ​​are stored, for example, in a comparison table.

[0020] Excess speed is generally a trigger criterion for activating the traction control system's correction. Excess speed is generally understood to be a speed that exceeds a predefined limit. In particular, excess speed is understood as the difference between the limit and the current speed. Excess speed is detected specifically when such a limit is exceeded and / or when a limit for speed increase (gradient) is exceeded.

[0021] Regarding the correction of the motor parameter request (motor current), a correction value is generally determined by weighting the overspeed with a correction factor. The correction is carried out by adjusting the request with the correction value, specifically by subtracting the correction value from the request, i.e., from the motor parameter value as specified by the control unit (page 5).

[0022] The requirement and the correction value are normalized to each other in that they have the same units, or rather, that the electrical signals corresponding to the requirement and the correction value, respectively, are represented by the same physical quantity. This normalization is achieved primarily using the correction factor. This factor is, in particular, a proportionality factor, meaning it has a fixed value.

[0023] If the correction value exceeds the value specified by the requirement, the corrected requirement is preferably limited to 0 in order to avoid negative values ​​for the corrected requirement.

[0024] Preferably, the correction factor is parameterizable, i.e., it is adjustable and can therefore be adapted to user behavior, for example.

[0025] For the purposes of this application, "parameterizable" generally means that, in principle, even after the manufacture and installation of the drive motor in the vehicle, adjustment options, such as for the correction factor, remain available. This parameterization and adjustment can be carried out, for example, by a specialist workshop or, if necessary, by the user themselves. If the user has the option to make adjustments, input via a user interface is specifically permitted.

[0026] In a preferred embodiment, the traction control system relies exclusively on data from the drive motor and, in particular, does not use any data on the instantaneous speed of a non-driven wheel. For example, the speed of the motor shaft is evaluated and used for the traction control system. This can be achieved using a sensorless method, a sensor, or both. Page 6

[0027] As an alternative to measuring the speed of the motor shaft, the speed of the driven wheel can also be used.

[0028] The speed of a non-driven wheel is usually determined using a sensor, in particular a wheel speed sensor, and compared with the speed of the driven wheel to determine if the driven wheel is slipping. Preferably, such a sensor for detecting the speed of a non-driven wheel is omitted and / or the instantaneous speed of such a non-driven wheel is not used for anti-slip control.

[0029] This results in an overall cost-effective anti-slip regulation.

[0030] Preferably, the system first checks whether a predefined driving condition is met, and the engine parameter requirement is only corrected if the driving condition is fulfilled. To check the driving condition, it is specifically verified whether the instantaneous power and / or torque and / or speed (of the drive motor) is within a predefined range or exceeds a predefined limit. This measure specifically verifies whether a critical driving situation exists that would require correction.

[0031] Alternatively or additionally, the procedure described here can also be activated or deactivated by user input to correct the requirement.

[0032] This driving condition, therefore, constitutes a second necessary trigger criterion for the application of the correction, in addition to the overspeed.

[0033] Preferably, an adjustment unit is integrated into the control loop, whereby the correction is reduced over time by means of an adjustment curve defined by the adjustment unit. In general, the correction is reduced according to the adjustment curve. The adjustment curve (page 7) thus achieves a smooth, harmonic transition to normal control, as it exists without correction. That is, the correction value is reduced gradually. This avoids abrupt changes in the requirement. The adjustment curve is, for example, a linear function, so that the correction value is reduced continuously and linearly over time. Alternatively, the adjustment curve can also be progressive, meaning that the correction value is initially reduced slowly and then more rapidly over time.In this context, an adjustment unit is generally understood to be a part of an electrical circuit that is used to appropriately influence a correction signal, where the correction signal represents the correction value.

[0034] In general, the control of the method described in this application is preferably carried out by a software algorithm (computer program) that influences the requirement and its correction. Therefore, the adaptation unit is also represented by a part of this software algorithm.

[0035] A particular advantage of this adaptation lies in its overcurrent limitation in certain driving situations. In driving situations such as jumps, which initially lead to overspeed due to the drive wheel spinning freely and then, upon impact with the ground, to a sudden increase in load, conventional control systems experience temporary current spikes and overcurrents due to this sudden increase in load. The adaptation described above provides a corrected demand in such situations, thus preventing or at least dampening temporary current spikes. Overall, this achieves both motor and battery protection by preventing temporary current spikes.

[0036] In particular, this ensures that the drive motor operates reliably at a desired operating point, even in a scenario with a sudden increase in load. Page 8

[0037] Preferably, the correction is maintained even after a correction request ceases, particularly when at least one trigger criterion (overspeed) is no longer present. In this case, the correction is reduced by the adaptation unit after the correction request ceases. In a preferred embodiment, the adaptation, and thus the reduction of the correction, is only activated once the correction request has ceased.

[0038] The correction request is, in particular, a digital signal with two states (on / off). Besides being dependent on the presence of at least one trigger criterion, the correction request can also be time-controlled, meaning that after initiating the correction, it remains active for a predetermined period.

[0039] The adjustment curve is preferably parameterizable, i.e., adjustable, as previously explained in connection with the correction value.

[0040] Preferably, the control loop further includes a limiter for the motor parameter, in particular a current limiter. This limiter is also preferably configurable. The limiter specifically defines a maximum value for the motor parameter. The limiter provides protection against overcurrent and current spikes.

[0041] The motor control system preferably includes a control circuit or feedback loop for the speed of the drive motor. The motor control system continuously determines a requirement for speed and / or torque. This requirement is hereinafter referred to as the speed requirement. It is implemented by a speed control unit, which regularly compares it with the actual instantaneous speed. If the instantaneous speed or the requested speed exceeds a predefined value or range, the speed control unit identifies this as overspeed (page 9) and outputs an overspeed signal, the magnitude of which correlates with the magnitude of the determined overspeed.

[0042] Preferably, the speed control loop has a speed limiter that can be parameterized, so that the adjustable speed does not exceed a predetermined value.

[0043] An embodiment of the invention is explained in more detail below with reference to the figures. These show simplified representations of:

[0044] FIG 1 shows a schematic block diagram of a vehicle with a drive motor and a motor control unit.

[0045] FIG 2 shows a comparative representation of the speed profile of a drive wheel or drive motor and the profile of a correction value, as well as

[0046] FIG 3 shows a comparison of the progression of an instantaneous requirement versus a corrected requirement and a corrective requirement.

[0047] FIG 1 shows a highly simplified block diagram of a vehicle 2, indicated by a dashed line, which is in particular a two-wheeled vehicle, for example an electrically powered motorcycle. The vehicle 2 comprises an electric drive motor 4, which is controlled by a motor controller 6. The drive motor 4 drives a drive wheel of the vehicle 2 (not shown in detail) to propel the vehicle 2. The motor controller 6 is a suitably designed control unit / circuit arrangement. This includes electronic components through which the functions described below are performed.

[0048] Within the motor control unit 6, a current control loop 8 and a speed control loop 10 are integrated in the exemplary embodiment, as well as a correction block 12. Page 10 The motor control unit 6 is controlled by a software algorithm (computer program). The various units of the motor control unit 6 are therefore (also) represented by different parts of this software algorithm. With regard to the various units such as the current control loop 8 or the speed control loop 10, these are represented, for example, by a current control program part and a speed control program part. The same applies to the correction block 12, which is represented by a correction program part.

[0049] The current control loop 6 has an integrated control unit 14 which, depending on an instantaneous motor current la, in particular based on field-oriented control and depending on other requirements and input values ​​not described in detail here, outputs a current demand lr. A suitable algorithm is implemented in the control unit 14 which determines the instantaneous demand lr. This demand lr is corrected as needed, as will be explained in more detail below.

[0050] For the correction, a correction value C is preferably subtracted from the current requirement lr, which is determined and provided by the correction block 12.

[0051] For the correction, for example, a computing unit is integrated within the current control loop 8, which in the exemplary embodiment is designed as a (negative) summing unit 16 to perform the subtraction. Thus, the correction value C is subtracted from the value represented by the requirement lr.

[0052] In the exemplary embodiment, a matching unit 17 and preferably also a current limiter 18 are arranged downstream of the summing unit 16.

[0053] At the end of this signal conditioning chain, a corrected request Ic for the motor current is obtained, which is used to control the currently operating drive motor 4 (page 11). This corrected request Ic preferably also forms the instantaneous motor current la as the input value for the control unit.

[0054] The speed control loop 10 preferably includes a speed control unit 20, which receives a speed request Sr as an input for a request for speed and / or torque, etc. The speed control loop 10 further includes a unit that provides the speed control unit 20 with a signal representing the instantaneous speed Sa of the drive motor 4. This specifically relates to the instantaneous speed of a rotor of the drive motor 4.

[0055] Within the speed control loop 10, a parameterizable speed limiter 22 is preferably integrated, via which, for example, a maximum speed / a maximum torque etc. can be specified.

[0056] In FIG 1, the parts of the motor control 6 which are parameterizable are colored grey.

[0057] The speed control loop 10, specifically the speed control unit 20, determines whether an overspeed Se exists and, if so, transmits a corresponding signal to the correction block 12. For this purpose, the speed control unit 20 compares, for example, the current speed Sa with the speed requirement Sr and determines the deviation as the overspeed Se, essentially through a target-actual comparison. Alternatively, the current speed Sa can also be compared with a fixed or, if applicable, dynamic speed limit, and the deviation between this limit and the current speed Sa is transmitted to the correction block 12 as the overspeed Se.

[0058] The correction block 12 has a correction unit 24 which provides a correction factor K. The correction factor K is, in particular, a proportional amplification factor. This is provided to a calculating element, in particular a multiplier 26.

[0059] Furthermore, the signal representing the overspeed Se is present at the multiplier 26.

[0060] Correction block 12 also includes a test unit 28, which is used to check whether certain driving conditions D are present. In particular, test unit 28 checks whether a specified power range and / or torque range and / or speed range is currently reached, and especially whether a corresponding limit value for the instantaneous power output, instantaneous torque output and / or instantaneous speed of the drive motor 4 is exceeded.

[0061] If the predetermined driving condition D is met, the test unit 28 sends a release signal to the multiplier 26, which then applies the correction value C, in particular by multiplication, to the overspeed Se. The aforementioned correction value C is obtained, which is transmitted to the current control loop 8 and further processed there, as previously explained.

[0062] The correction of the current requirement lr with the correction value C can in principle also take place in the correction block 12 and the correspondingly corrected signal can then be further processed, for example, in the current control loop 8.

[0063] The individual arrows shown in FIG. 1 between the various units and blocks of the motor control 6 are each represented by corresponding electrical signals, specifically voltage signals. At the same time, the different arrows represent the data transfer between the various program parts of the computer program when it is executed.

[0064] The signal for the overspeed Se correlates in particular with the overspeed Se, i.e., the corresponding signal is proportional to the detected overspeed Se. Page 13

[0065] The course of the various signals for the traction control system is explained in more detail in simplified terms using FIG 2.

[0066] In FIG. 2, the signal waveform for the instantaneous velocity Sa is shown at the top, the signal for the corrected current demand Ic is shown in the middle, and the signal for a correction demand F is shown at the bottom. This correction demand F has two states (on / off). This correction demand F is active, for example, as long as an overspeed Se is detected. Alternatively, a purely time-based control can also be implemented.

[0067] In the event of a particularly abrupt increase in speed of the drive motor 4 and thus also of the drive wheel driven by it, an overspeed Se is detected and the correction of the current requirement lr is initiated, as described in FIG 1.

[0068] In addition, it is specifically provided that the correction request F is transmitted as a signal to the current control loop 8 and is particularly present at the adaptation unit 17.

[0069] The correction requirement F generally defines a correction phase I.

[0070] In the present embodiment, this process is initially completed when the velocity Sa decreases again.

[0071] This correction phase I is followed by an adjustment phase II, during which the correction, and thus in particular the correction value C, is continuously reduced. At the end of correction phase II, therefore, no further correction is made, and the uncorrected current demand lr is no longer present.

[0072] The curve for the instantaneous velocity Sa clearly shows that this velocity Sa drops abruptly again, and in particular, as shown on page 14, falls below a value before rising again. This represents, for example, the situation during a jump, when the drive wheel lifts off, leading to an abrupt increase in speed. Conversely, during landing, this results in a sharp deceleration. As explained earlier, this situation presents an abrupt increase in load on the drive motor 4, which would typically lead to short-term current spikes with a conventional control system. Specifically, the adjustment proposed here, even following a correction request F, maintains a smooth, corrected current demand Ic and avoids current spikes.

[0073] This avoidance of current peaks is illustrated again in FIG. 3. In the upper section, the curve of the current demand lr is shown in comparison to the curve of the corrected current demand Ic. In the lower section, the correction demand F (as a digital signal between 1 and 0) is shown. Correction phase I and adaptation phase II are again depicted. It is clearly visible that in adaptation phase II, the corrected current demand Ic is continuously reduced to the (regular) current demand lr. At the end of adaptation phase II, the (regular) uncorrected current demand lr is present again.

[0074] The method described here therefore implements effective traction control. A key concept for the traction control lies in monitoring for overspeed Se and reducing and correcting the current demand lr by the correction value C during the correction phase I. This leads to a reduction and control of the motor speed, and thus also of the drive wheel and therefore of the vehicle, resulting in effective traction control. This also facilitates the recovery of sufficient traction. Page 15. Another particular advantage of the proposed solution is that current spikes are avoided, especially when traction of the drive wheel is suddenly regained.

[0075] Due to the control of the motor control, in particular the current requirement lr, it is made easier to operate the drive motor 4 at the operating point, especially in the event of a sudden increase in load.

[0076] The traction control system is characterized in particular by the following measures:

[0077] - The overspeed Se is detected, which is an indication of the loss of traction of the drive wheel.

[0078] - The (proportional) correction factor K is applied to the value for the overspeed Se, resulting in the correction value C. - The correction value C is then used to reduce the (instantaneous) current requirement lr, resulting in a corrected current requirement Ic.

[0079] This reduction in current requirement leads to a reduction in the speed of the drive motor 4, in particular of its rotor, which in particular enables the recovery of traction and allows the driver to maintain control of the vehicle.

[0080] In addition to this anti-slip control, overcurrent protection is preferably implemented by preventing current spikes. This is specifically achieved through adaptation phase II and adaptation unit 17.

[0081] With the aid of this adaptation unit 17, active monitoring is provided, in particular, to determine whether the current demand lr has been / is being corrected. This is done, for example, by comparison with the signal of the correction demand F. The adaptation is carried out at the end of the correction demand F. The adaptation curve, which is designed, for example, as a ramp, prevents the current demand lr from abruptly switching back from the corrected current demand Ic (page 16) to the regular, instantaneous current demand lr. This measure avoids the occurrence of current spikes, especially in cases where the drive wheel lands back on the ground after a jump (page 17).

[0082] Reference symbol list

[0083] 2 vehicles

[0084] 4 Drive motor

[0085] 6 Motor control

[0086] 8 Current control loop

[0087] 10 Speed ​​control loop 12 Correction block

[0088] 14 Control unit

[0089] 16 summers

[0090] 17 Adjustment unit

[0091] 18 current limiters

[0092] 20 Speed ​​control unit 22 Speed ​​limiter 24 Correction unit

[0093] 26 Multipliers

[0094] 28 test units

[0095] lr requirement

[0096] I corrected the request

[0097] la instantaneous motor current

[0098] C correction value

[0099] Sr speed requirement Sa current speed Se overspeed

[0100] K correction factor

[0101] Driving conditions

[0102] F Correction request

[0103] I Correction phase

[0104] 11. Adaptation phase

Claims

Page 18 Claims 1. Method for controlling an electric drive motor (4) of an electrically driven vehicle (2), in particular a two-wheeled vehicle, namely for an anti-slip control system, wherein - a momentary request (lr) for a motor parameter, in particular for a motor current, is issued by a control unit (14) integrated in a control loop (8) for controlling the drive motor (4), - the drive motor (4) is monitored with regard to overspeed (Se), - in the event of detection of an overspeed (Se) in the control loop (8) of the drive motor (4) intervention occurs and the instantaneous requirement (lr) is corrected so that a corrected requirement (Ic) is obtained which is used for the control of the drive motor (4).

2. Method according to the preceding claim, wherein the overspeed (Se) is determined on the basis of a parameter of the drive motor (4), in particular on the basis of a rotational speed of the drive motor (4).

3. Method according to one of the preceding claims, wherein a correction value (C) for correcting the requirement (lr) is determined by weighting the overspeed (Se) with a correction factor (K) and correcting the requirement (lr) with the correction value (C), in particular by subtraction.

4. Method according to the preceding claim, wherein the correction factor (K) is parameterizable.

5. Method according to one of the preceding claims, wherein the anti-slip control relies exclusively on data from the drive motor (4). Page 19 6. Method according to one of the preceding claims, wherein the use of an instantaneous speed of a non-driven wheel is dispensed with for the anti-slip control.

7. Method according to one of the preceding claims, in which it is checked whether a predetermined driving condition (D) is met, for example whether an instantaneous power of the drive motor (4) or an instantaneous driving speed (Sa) is within a defined range, and the requirement (lr) is corrected only if the driving condition (D) is met.

8. Method according to one of the preceding claims, wherein the correction is reduced over time, in particular by means of an adjustment unit (17) according to an adjustment profile.

9. Method according to the preceding claim, wherein the correction is maintained even after the elimination of a correction requirement and the reduction of the correction is carried out after the elimination of the correction requirement.

10. Method according to one of the two preceding claims, wherein the adaptation process is parameterizable.

11. Method according to one of the preceding claims, wherein the control loop (8) has a current limiter (18) which is in particular parameterizable.

12. Vehicle (2), in particular a two-wheeled vehicle, with an electric drive motor (4) and with a motor control unit (6) which is equipped to carry out the method according to one of the preceding claims and for this purpose - has a control loop (8) for controlling the drive motor (4), with an integrated control unit (14) which is configured to issue an instantaneous request (lr) for a motor parameter during operation, wherein the motor control (6) is further configured to monitor the drive motor (4) with regard to overspeed (Se), Page 20 - in the event of detection of an overspeed (Se) to initiate an intervention in the control loop (8) such that the current requirement (lr) is corrected, so that a corrected requirement (Ic) is obtained which is used for the control of the drive motor (4).

13. Computer program comprising instructions that cause the execution of the method according to one of claims 1 to 11 when the program is executed by a computer.

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