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CN-122003336-A - Motor vehicle deceleration by means of an electric motor

CN122003336ACN 122003336 ACN122003336 ACN 122003336ACN-122003336-A

Abstract

A motor vehicle (105) comprises a drive wheel (115) which rolls on a ground surface (120) and an electric drive machine (110) which acts on the drive wheel (115). A method (200) for decelerating a driving motor vehicle (105) comprises the steps of determining (215, 225) a momentum of the motor vehicle (105), determining (245) a deceleration direction based on the momentum, determining (240) a deceleration force based on a deceleration desire (125), determining (255) a deceleration torque (130) based on the deceleration direction, the deceleration force and an effective lever between a rotational axis of the drive machine (110) and the ground (120), and controlling (255) the drive machine (110) to provide the deceleration torque (130).

Inventors

  • F. Hellsman

Assignees

  • 宝马股份公司

Dates

Publication Date
20260508
Application Date
20241213
Priority Date
20240110

Claims (14)

  1. 1. A method (200) for decelerating a driving vehicle (105) by means of an electric drive machine (110) acting on a driving wheel (115) of the vehicle (105) rolling on a ground surface (120), wherein the method (200) comprises the steps of: -determining (215, 225) a momentum of the motor vehicle (105); -determining (245) a deceleration direction based on the momentum; -determining (240) a retarding force based on the retarding desire (125); -determining (255) a deceleration torque (130) based on the deceleration direction, the deceleration force and an effective lever between a rotational axis of the drive machine (110) and the ground (120), and -Controlling (255) the drive machine (110) to provide the retarding torque (130).
  2. 2. The method (200) of claim 1, wherein if the momentum is below a predetermined threshold, the retarding force is reduced below the retarding desire (125).
  3. 3. The method (200) of claim 2, wherein the reducing occurs linearly with respect to the momentum.
  4. 4. The method (200) of claim 2, wherein the decrease is determined in relation to a predetermined characteristic curve for momentum.
  5. 5. The method (200) of any preceding claim, wherein the magnitude of the retarding force is limited upwardly to a predetermined magnitude.
  6. 6. The method (200) according to any one of the preceding claims, wherein the retarding force is determined such that a stationary motor vehicle (105) is held on an uphill or a downhill slope.
  7. 7. The method (200) according to any one of the preceding claims, wherein the change in momentum of the motor vehicle (105) is determined based on at least one force acting on the motor vehicle (105) in a direction of movement.
  8. 8. The method (200) of claim 7, wherein the force comprises one of a driving force generated by a driving motor, a friction force generated by a friction brake, a rolling resistance, an air resistance, and a sliding down force.
  9. 9. The method (200) according to any one of claims 7 or 8, wherein a current momentum is determined based on the determined momentum and the momentum change.
  10. 10. The method (200) of claim 9, wherein the determined momentum is low pass filtered and the momentum change is high pass filtered, wherein the time constants of the two filters are equal to each other.
  11. 11. The method (200) of claim 10, wherein the time constant is determined (230) as a function of a driving state of the motor vehicle (105).
  12. 12. The method (200) according to claim 10 or 11, wherein the current momentum is determined (230) based on the determined momentum and the determined momentum change by means of a complementary filter.
  13. 13. An apparatus (100) for decelerating a driving vehicle (105) by means of an electric drive machine (110) acting on a driving wheel (115) of the vehicle (105) rolling on a ground surface (120), wherein the apparatus comprises: -means (135) for determining the momentum of the motor vehicle (105); -a first interface (140) for obtaining a deceleration desire (125); -a second interface (145) for controlling the drive machine (110); -processing means (135) arranged to: Determining a deceleration direction based on the momentum; Determining a deceleration force based on the deceleration desire (125); Determining a deceleration moment (130) based on the deceleration direction, the deceleration force and an effective lever between a rotational axis of the drive machine (110) and the ground (120), and The drive machine (110) is controlled to provide the retarding torque (130).
  14. 14. A motor vehicle (105) comprising an apparatus (100) according to claim 13.

Description

Motor vehicle deceleration by means of an electric motor Technical Field The invention relates to decelerating a motor vehicle by means of an electric motor. The invention relates in particular to decelerating a scooter-type motor vehicle by means of an electric drive. Background The scooter comprises an electric motor acting on the driving wheels of the scooter. The scooter may be decelerated by providing a torque on the driving wheels by means of the driving machine, which causes a deceleration force. The torque may be controlled in dependence on the rotational speed of the driving wheel such that the torque is zero when the rotational speed of the driving wheel drops to zero and the scooter reaches a stationary state. Since conventional sensors for determining the rotational speed of the drive wheel only provide information about the rotational speed of the drive wheel, but not about the rotational direction of the drive wheel, the rotational speed of the drive machine can instead be correspondingly converted and used for control. The rotational speed and the rotational direction of the drive machine can be determined, for example, by means of sensors or can be provided by field-oriented control. If there is a slip between the drive wheel and the ground, the speed of travel of the motor vehicle and in particular its stationary state may not be precisely determined. Slip can occur in particular during severe deceleration and/or at low driving speeds. Thus, for example, the drive wheel can be rotated in the opposite direction, while the scooter still travels forward, so that the drive wheel is first rotated forward again and the scooter can briefly accelerate rather than decelerate. The stopping distance of the scooter type motor vehicle can thereby be prolonged. In certain situations, control may begin to oscillate such that control of the scooter may be adversely affected. Disclosure of Invention The invention is based on the object of providing an improved technique for braking a motor vehicle by means of an electric drive machine. The invention solves this object by means of the subject matter of the independent claims. The motor vehicle comprises a drive wheel which rolls over the ground and an electric drive machine which acts on the drive wheel. A method for decelerating a traveling motor vehicle includes the steps of determining a momentum of the motor vehicle, determining a deceleration direction based on the momentum, determining a deceleration force based on a deceleration desire, determining a deceleration torque based on the deceleration direction, the deceleration force, and an effective lever between a rotational axis of a drive machine and a ground surface, and controlling the drive machine to provide the deceleration torque. It is proposed to derive the driving speed of the motor vehicle from the momentum of the motor vehicle, so that the deceleration can be controlled in an improved manner. Momentum can be reliably and accurately determined, especially when the motor vehicle has a predetermined minimum speed below which slip is more likely to occur at deceleration. The deceleration torque can be controlled precisely with improved accuracy and in particular in the direction of the deceleration torque. Even if the deceleration moment acting on the driving wheel is so large that the driving wheel rotates against the running direction of the motor vehicle, the regulation hunting can be prevented. Reliable and accurate braking techniques can be provided for the driver of the motor vehicle. The advantages of deceleration by means of the electric drive, such as low wear, the possibility of recovering the kinetic energy of the motor vehicle or low emissions caused by wear, can be exploited in this case. The driving speed of the motor vehicle can be determined on the basis of the rotational speed of the electric drive and the effective lever. The effective lever may be determined based on the circumference of the drive wheel and the effective reduction ratio between the drive wheel and the drive machine. The rotational speed of the drive machine can be determined by means of a sensor or can be provided by a control device of the drive machine. Alternatively, the driving speed of the motor vehicle can also be determined by means of a rotational speed sensor on the drive wheel. Preferably, the drive wheel rotational speed is determined during a period in which the value of the torque achieved by the drive machine is below a predetermined threshold value, in order to facilitate slip-free operation of the drive wheels. Alternatively, a rotational speed sensor may be used on the non-driving wheels of the motor vehicle for determining the speed. The speed may also be determined in other ways, for example by means of a positioning system based on GNSS, such as GPS, galileo or glonass. The mass of the motor vehicle can be determined by means of a mass estimator which, for example, evaluates how the speed