DE102018010033A1 - Method for avoiding a wheel slip in electrically driven axles of a vehicle - Google Patents

Abstract

The invention relates to a method for avoiding a wheel slip in electrically driven axles of an electrically driven vehicle, in which a first control (1) for setting motor and generator torques of at least one electric machine with a second, a first ASR controller (11) Control (5) cooperates to evaluate the vehicle condition. In a method in which adhesion of the wheels is reliably prevented, the first controller (1) comprises a second ASR controller (9), wherein the torque is reduced in response to a wheel slip detected by the second ASR controller (9) ,

Description

The invention relates to a method for avoiding wheel slippage in electrically driven axles of a vehicle, in which a first control for setting engine and generator torques of at least one electric machine cooperates with a second controller comprising a first ASR controller for evaluating the vehicle condition.

From the DE 10 2013 206 379 A1 a method for slip control on a motor vehicle is known, the drive unit has at least one electric machine, namely for traction control in train operation. An ESP control device, which determines a specific driving situation for each driven axle or driven wheel target slip and regulates depending on the driving situation-dependent desired slip the operation of the drive unit, the ESP control device depending on the driving situation-dependent nominal slip for each driven by an electric machine of the drive unit Axis or for each driven by an electric machine of the drive unit wheel determines a target engine speed for each electric machine of the drive unit.

In such systems, due to the dynamic torque build-up, the static friction of the wheels of the vehicle may decrease, particularly in downhill situations or on low friction road surfaces.

The object of the invention is to provide a method for avoiding a wheel slip, in which a Haftungsabriss the wheels is prevented.

The invention results from the features of the independent claims. Advantageous developments and refinements are the subject of the dependent claims. Other features, applications and advantages of the invention will become apparent from the following description, as well as the explanation of embodiments of the invention, which are illustrated in the figures.

The object is achieved by a method in that the first controller comprises a second ASR controller, wherein the torque is reduced as a function of a wheel slip detected by the second ASR controller. Due to the fact that the first controller has its own ASR controller, a rapid reaction to reduce the torque can occur as the static friction of the wheels decreases. Thus, a loss of adhesion is reliably prevented by a reduced torque.

Advantageously, the second ASR controller of the first controller detects the individual slip of each wheel of the vehicle and / or an axle slip of an axle bearing two wheels. This improves the accuracy in reducing the torque.

In one embodiment, sensor data for detecting a current state of the electric machine forming the torque is supplied to the first controller. Thus, not only the current vehicle state, but also the current state of the electric motor is included in the determination of the torque.

In one variant, the sensor data include rotational speeds of the axle and / or wheel speeds of the individual wheels, which act on the torque.

In a further development, the first controller determines from the wheel speeds and a steering angle provided by a third control effective wheel speeds, which enter into a factor by which a target torque of the electric machine is reduced in order to reduce a wheel slip on a driven axle. This further increases the accuracy of the torque control.

In one embodiment, a desired wheel speed calculated by the second control is transmitted to the first control, from which, together with the effective wheel speeds, the factor for reducing the setpoint torque is determined. As a result, the static friction of the wheels is reliably determined, which has an advantageous effect on the adjustment of the torque.

Advantageously, each axis of the vehicle is driven by a respective electric machine connected to the second controller, wherein an asymmetric slip as the difference between the two wheel speeds of the respective axis and / or a symmetrical slip as the difference of an average of the two wheel speeds of the respective axis to that of the determined second speed controller is determined and in its dependence two separately parameterizable P-controller control the torque on the respective axis. This results in a particularly effective torque control of the respective wheels or on the respective axis.

In a further embodiment, the first control slows down the reduction of torque in the absence of wheel slip. This avoids vibration effects on the axles or wheels.

In order to adapt the comfort settings of the vehicle to the wishes of the driver, a control characteristic of the first and / or second ASR controller is influenced manually by driving program.

Further advantages, features and details will become apparent from the following description in which - where appropriate, with reference to the drawings - at least one embodiment is described in detail. Described and / or illustrated features may form the subject of the invention itself or in any meaningful combination, optionally also independent of the claims, and in particular may also be the subject of one or more separate application / s. The same, similar and / or functionally identical parts are provided with the same reference numerals.

• 1: ein Ausführungsbeispiel des erfindungsgemäßen Verfahrens.

It shows:

• 1 : an embodiment of the method according to the invention.

In a vehicle having electrically driven axles, wherein an electric machine is arranged on each axle, a control device is provided for each electric machine 1 to provide motor and regenerative moments. To this controller 1 are sensors 3 connected, which detect the state, in particular the rotational speed of the torque-generating electric machine. A second controller 5 is with the first controller 1 connected. The second control unit 5 determined from various sensor data of the vehicle, a current state of the vehicle and the wheels. This controller 5 is designed as ESP control unit. In addition, there is a third control unit 7 present, which regulates an electric steering and detects a steering angle of the vehicle. In addition, the first control unit includes 1 an ASR controller 9 , wherein the second control device 5 also an ASR controller 11 having.

The one in the first control unit 1 existing ASR controllers 9 is designed so that both a Einzelradschlupf the wheels of the vehicle as well as an axle slip of an axle of the vehicle is detected, to which two wheels are attached. The sensors 3 include speed sensors which read either the wheel speed of the two axles or the four wheel speeds of the four vehicle wheels. The second control unit 5 calculated from the sensors 13 supplied signals a target wheel speed and transmits them to the first control unit 1 , This calculated from the transmitted wheel speeds and that of the third control unit 7 transmitted steering angle effective wheel speeds. These effective wheel speeds become common with that of the second controller 5 transmitted desired wheel speed by the first controller 1 determines a factor by which the target torque for the electric machine must be reduced to prevent wheel slip on the driven axle.

• - Erstens wird ein asymmetrischer Schlupf bestimmt, welcher die Differenz der beiden Raddrehzahlen einer Achse zueinander darstellt.
• - Zweitens wird ein symmetrischer Schlupf bestimmt, der eine Differenz eines Mittelwertes der beiden Raddrehzahlen zu der Solldrehzahl angibt, die von dem zweiten Steuergerät 5 ermittelt wird.

Auf Basis dieser beiden Schlupfwerte regeln zwei getrennt parametrierbare P-Regler das Motormoment der jeweiligen elektrischen Maschine an der jeweiligen Achse. Detektiert das erste Steuergerät 1, dass kein Radschlupf anliegt, so wird die Momentenreduktion kontinuierlich wieder zurückgenommen.On each axle of the vehicle is in each case an electric machine with a first control unit 1 arranged, with each control unit 1 one ASR controller each 9 having. Each control unit 1 via a respective discrete line not shown with a common second control unit 5 connected. The wheel speeds of the corresponding wheels are transmitted quasi-latency-free via these lines. With these wheel speeds and that of the second control unit 5 predetermined setpoint speed, two different slip values are determined.

• - First, an asymmetric slip is determined, which represents the difference between the two wheel speeds of an axis to each other.
• Secondly, a symmetrical slip is determined, which indicates a difference between an average value of the two wheel speeds to the setpoint speed, that of the second control unit 5 is determined.

On the basis of these two slip values, two separately parameterizable P controllers control the motor torque of the respective electrical machine on the respective axis. Detects the first controller 1 in that no wheel slip is applied, the torque reduction is continuously reduced again.

Although the invention has been further illustrated and explained in detail by way of preferred embodiments, the invention is not limited by the disclosed examples, and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention. It is therefore clear that a multitude of possible variations exists. It is also to be understood that exemplified embodiments are really only examples that are not to be construed in any way as limiting the scope, applicability, or configuration of the invention. Rather, the foregoing description and description of the figures enable one skilled in the art to practice the exemplary embodiments, and those skilled in the art, having the benefit of the disclosed inventive concept, can make various changes, for example, to the function or arrangement of individual elements recited in an exemplary embodiment, without Protection area defined by the claims and their legal equivalents, such as further explanations in the description.

LIST OF REFERENCE NUMBERS

1

control unit

3

sensors

5

control unit

7

control unit

9

TCS controller

11

TCS controller

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102013206379 A1 [0002]

Claims (9)

Method for avoiding wheel slippage in the case of electrically driven axles of an electrically driven vehicle, in which a first control (1) for setting motor and generator torques of at least one electric machine with a second control (5) comprising a first ASR controller (11) cooperates to evaluate the vehicle condition, characterized in that the first controller (1) comprises a second ASR controller (9), wherein the torque is reduced in dependence on a by the second ASR controller (9) detected wheel slip. Method according to Claim 1 , characterized in that the second ASR controller (9) of the first controller (1) detects the individual slip of each wheel of the vehicle and / or an axle slip of an axle bearing two wheels. Method according to Claim 1 or 2 , characterized in that the first controller (1) sensor data for detecting a current state of the torque-forming electric machine are supplied. Method according to Claim 3 , characterized in that the sensor data include rotational speeds of the axle and / or wheel speeds of the individual wheels on which the torque acts. Method according to at least one of the preceding claims, characterized in that the first controller (1) determines from the wheel speeds and a steering angle provided by a third control (7) effective wheel speeds, which enter into a factor by which a setpoint torque of the electric machine is reduced is used to prevent wheel slippage on a driven axle. Method according to Claim 5 , characterized in that one of the second controller (5) calculated target wheel speed is transmitted to the first controller (1), from which determines the first control (1) together with the effective wheel speeds the factor for reducing the target torque. Method according to at least one of the preceding claims, characterized in that each axle of the vehicle is driven by an electric machine connected to the second control (5), an asymmetrical slip being the difference between the two wheel speeds of the respective axle and / or a symmetrical slip is determined as the difference of an average value of the two wheel speeds of the respective axis with the setpoint speed determined by the second control (5) and in whose dependence two parameterisable P-controllers control the torque on the respective axle. Method according to at least one of the preceding claims, characterized in that the first controller (1) slowly decreases the reduction of the torque in the absence of wheel slip. Method according to at least one of the preceding claims, characterized in that a control characteristic of the first (11) and / or second ASR controller (9) are influenced manually by driving program.

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