Anti-nose down torque control for electric vehicle braking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Fuel cell and electric vehicles experience a heightened 'nose down' phenomenon during braking due to their forward-biased center of gravity and lack of idle state torque, leading to increased rotational moment and reduced riding quality.
Innovation Solution
An anti-nose down torque control system that applies a forward-direction torque to the motor during the last braking stage, calculated from a braking deceleration-torque map and determined using a motor rotating speed-torque map, gradually increasing and maintaining maximum torque until the vehicle stops to decrease braking deceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If braking force is applied to the vehicle, then vehicle deceleration is achieved, but nose down phenomenon occurs due to rotational moment
Solution Approach 1:
The control system applies anti-nose down torque to the motor in advance during the braking process, specifically when motor rotating speed is below a predetermined threshold. This counteracting torque opposes the rotational moment caused by braking force, preventing the nose down phenomenon before it fully manifests, thus resolving the contradiction between achieving deceleration and preventing harmful vehicle attitude changes
Solution Approach 2:
The anti-nose down torque functions as a counterbalancing force against the harmful rotational moment generated during braking. By applying this opposing torque through the motor, the system creates a counterweight effect that neutralizes the nose down tendency, allowing effective braking while maintaining vehicle attitude stability
2Use of energy by moving object
If motor rotating speed is low during braking, then energy recovery is reduced, but nose down phenomenon increases due to lack of idle state torque
Solution Approach 1:
The control system changes the operational parameters of the motor by applying anti-nose down torque specifically when motor rotating speed falls below a predetermined threshold. This parameter-based control strategy allows the system to provide counteracting torque precisely when needed (at low speeds where nose down phenomenon is most problematic) without continuously compromising energy recovery efficiency during higher speed braking where regenerative braking is more effective
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The anti-nose down torque control system effectively alleviates the nose down phenomenon by reducing braking deceleration and enhancing riding quality during vehicle braking, with the torque disappearing once deceleration reaches zero after stopping.
Implementation Method 1
a forward direction torque referred to as an anti-nose down torque may be applied to the motor
Implementation Method 2
braking force is applied rearward to a tire tread lower than a center of gravity of the vehicle
Implementation Method 3
an inertial force is applied to the center of gravity of the vehicle in a progress direction of the vehicle
Data Source
AI summary
An anti-nose down torque control system and method for a vehicle is provided that prevents a nose down phenomenon where, during braking of a vehicle, front parts of the vehicle rotates forward. The method includes braking, by a controller, the vehicle being driven by a motor and applying the anti-nose down torque in a forward direction to the motor in response to a deceleration and a vehicle speed in a last braking stage. In addition, the controller is configured to decrease a braking deceleration and reduce a nose down phenomenon by the anti-nose down torque.