Electrified Vehicle Deceleration Control via Dynamic Torque Adjustment
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Solution Overview
Problem
Electrified vehicles face challenges in maintaining an ideal deceleration rate during encounters with oncoming objects, leading to either excessive slowing or coasting, which requires driver intervention to adjust speed.
Innovation Solution
A vehicle system and method that adjust the deceleration rate of an electrified vehicle by determining the closing rate to an oncoming object, calculating a desired deceleration rate, and applying a negative torque demand to the electric machine through regenerative braking, without applying the brakes, by modifying the torque demand associated with a predefined accelerator pedal position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If regenerative braking is applied during lift pedal conditions, then fuel consumption is reduced and energy is recovered, but the deceleration rate becomes fixed and cannot adapt to varying distances to oncoming objects
Solution Approach 1:
The system dynamically adjusts the deceleration rate by modifying the negative torque demand based on real-time detection of oncoming objects and calculation of closing rates. The controller continuously updates the torque demand to achieve a desired deceleration rate that adapts to varying distances and speeds, transforming the static regenerative braking system into a dynamic one that responds to changing driving conditions
Solution Approach 2:
The system changes the torque demand parameter associated with accelerator pedal positions based on the detected closing rate to oncoming objects. By adjusting this parameter dynamically, the system achieves variable deceleration rates while maintaining regenerative braking, allowing the vehicle to slow down more or less depending on the distance and speed of oncoming objects
2Device complexity
If a fixed deceleration rate is used during lift pedal conditions, then the control system is simple, but the vehicle may slow too quickly or coast too much requiring driver intervention
Solution Approach 1:
The system provides self-service by automatically detecting oncoming objects, calculating closing rates, and adjusting deceleration rates without driver input. The controller monitors accelerator pedal positions and vehicle speed, then autonomously modifies torque demand to achieve desired deceleration, eliminating the need for drivers to manually tip in or apply brakes to adjust speed
3Speed
If the vehicle slows too quickly when an oncoming object is far away, then stopping distance is reduced, but the driver must tip in to reach the object
Solution Approach 1:
The system uses feedback from object detection sensors and speed sensors to continuously monitor the closing rate to oncoming objects. Based on this feedback, the controller adjusts the torque demand and deceleration rate in real-time, ensuring the vehicle slows at an appropriate rate that allows it to reach distant objects without requiring driver intervention
4Use of energy by moving object
If the vehicle coasts too much when an oncoming object is close, then energy recovery is maximized, but the driver must apply brakes to stop
Solution Approach 1:
The system monitors the closing rate to nearby oncoming objects through sensor feedback and adjusts the negative torque demand accordingly. When objects are detected at close distances, the controller increases the deceleration rate to ensure the vehicle stops in time, preventing the need for driver brake application while maintaining optimal energy recovery conditions
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
Enables smooth and linear deceleration of the electrified vehicle to match the closing rate with the oncoming object, reducing the need for driver intervention and maintaining efficient regenerative braking without brake application.
Implementation Method 1
Regenerative braking can be achieved during braking or lift pedal conditions by configuring the electric machine as a generator. The act of generating power with the electric machine creates a negative braking torque, or regenerative torque, on the electric machine.
Data Source
AI summary
A method according to an exemplary aspect of the present disclosure includes, among other things, controlling an electrified vehicle by adjusting a deceleration rate based on a closing rate of the electrified vehicle to an oncoming object.