EV Travel Control for Smooth Deceleration in One-Pedal Driving
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Solution Overview
Problem
Existing electric vehicle travel control systems cause rapid deceleration when the accelerator pedal is released, leading to decreased operability as the vehicle speed drops contrary to the driver's intention.
Innovation Solution
A travel controlling device for electric vehicles with a traction motor that generates a first braking torque for rapid deceleration and a second braking torque for gradual deceleration, depending on the accelerator opening and vehicle speed, to manage vehicle speed changes in accordance with the driver's intent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the traction motor generates a braking torque to enable one-pedal drive and rapid deceleration, then the vehicle can be stopped without brake operation, but the vehicle speed rapidly decreases contrary to the driver's intention when the accelerator pedal is released
Solution Approach 1:
The control device dynamically adjusts the braking torque magnitude based on real-time detection of accelerator opening change rate. When the accelerator opening changes rapidly (indicating sudden release), a larger braking torque is applied for quick deceleration. When the accelerator opening changes gradually, a smaller braking torque is applied to maintain smooth coasting behavior, thus adapting the deceleration characteristics to match driver intent
Solution Approach 2:
The system changes the control parameter (braking torque magnitude) based on the change rate of accelerator opening. By monitoring how quickly the accelerator opening changes, the control device selects appropriate deceleration rates, transforming a fixed deceleration behavior into a variable one that responds to driver input characteristics
2Productivity
If the traction motor generates a large braking torque when the accelerator opening decreases, then the vehicle deceleration performance is improved, but the operability deteriorates due to unexpected rapid speed decrease
Solution Approach 1:
The control device continuously monitors the accelerator opening and its change rate, using this feedback to determine the appropriate braking torque magnitude. This closed-loop control ensures that deceleration behavior aligns with driver intent, preventing unexpected rapid speed decreases while maintaining effective deceleration performance
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
Prevents rapid vehicle speed decreases, allowing drivers to control the vehicle without deteriorating operability by selectively generating braking torques based on accelerator pedal operation, enabling both rapid deceleration and gradual coasting.
Implementation Method 1
a control unit to cause the traction motor to generate, when an accelerator opening corresponding to an amount of an operation to an accelerator pedal decreases, a first braking torque
Data Source
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AI summary
[Object] It is to provide a travel controlling device of an electric vehicle capable of preventing, when an accelerator opening decreases, a vehicle speed from rapidly decreasing contrary to a driver's intention, allowing a driver to drive a vehicle without deteriorating an operability. [Solution] An ECU causes a traction motor to generate a non-one-pedal drive braking torque with which a vehicle speed gradually decreases (step S9), if a change rate of an accelerator opening is smaller than a predetermined rate ("YES" at step S5) when the vehicle speed is higher than a predetermined speed. The ECU includes driving and braking ranges to generate one-pedal and non-one-pedal drive braking torques respectively when the accelerator opening decreases, and causes the traction motor to generate the non-one-pedal drive braking torque if the accelerator opening within the driving range decreases with the vehicle speed higher than the predetermined speed and the change rate of the accelerator opening smaller than the predetermined rate.