Virtual Gear Shift Torque Control for Engine Braking
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Solution Overview
Problem
Electric vehicles (EVs) lack a distinct gear shift sensation during engine braking due to the absence of differentiated torque profiles for each gear stage in their virtual gear shift (VGS) mode, which fails to replicate the deceleration experience of internal combustion engine vehicles.
Innovation Solution
A method that divides the coasting torque profile into separate profiles for each gear shift stage within the VGS mode, allowing for engine braking control through a target coasting torque and gear shift feeling torque, enabling a distinct deceleration sensation by varying torque levels during gear shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single coasting torque profile is used for regenerative braking in EVs, then the braking control is simple, but the gear shift sensation and deceleration distinction are lost
Solution Approach 1:
The single coasting torque profile is segmented into multiple gear-stage-specific coasting torque profiles (first, second, third, and fourth coasting torque profiles corresponding to different gear stages). This segmentation allows the system to provide distinct deceleration characteristics for each virtual gear stage during regenerative braking, creating a noticeable gear shift sensation while maintaining straightforward control implementation.
2Ease of manufacture
If the coasting torque profile is divided into multiple profiles for each gear stage, then the gear shift sensation is enhanced, but the control system complexity increases
Solution Approach 1:
The multiple gear-stage-specific coasting torque profiles are integrated into a single regenerative braking control system that automatically selects the appropriate profile based on the current virtual gear stage. This multi-functional approach allows one control system to handle both the differentiation of gear shift sensations and the coordination of regenerative braking across all gear stages, avoiding the need for separate control systems for each gear stage.
3Use of energy by moving object
If regenerative braking is used without gear-stage differentiation, then energy recovery is efficient, but the deceleration experience lacks distinction
Solution Approach 1:
The regenerative braking system dynamically adjusts the coasting torque profile based on the current virtual gear stage during deceleration. As the vehicle transitions between gear stages, the system switches between different coasting torque profiles (first through fourth profiles), creating dynamic variations in deceleration characteristics that provide a distinct gear shift sensation while continuously optimizing energy recovery efficiency.
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
This approach provides a noticeable engine braking feeling similar to internal combustion engine vehicles by differentiating torque profiles for each gear stage, enhancing the deceleration experience in EVs through regenerative braking and gear shift torque control.
Implementation Method 1
The motor is connected to the battery as a driving source of the EV and the battery is configured to be charged and discharged through the inverter
Data Source
AI summary
A method of implementing engine braking using a virtual gear shift (VGS) system of an electric vehicle (EV), which is connected with a VGS mode torque profile map, performs power-off down shift control by turning a VGS function on in response to an accelerator position scope (APS) off signal and a paddle shift signal. The method performs shift progress using a gear shift feeling torque compensating for a torque difference between a target gear shift stage and a current gear shift stage of the VGS. The method also controls vehicle deceleration to allow an amount of regenerative braking to increase using a target coasting torque as a gear is shifted to a lower gear shift stage to implement an engine braking feeling due to an increase in a deceleration feeling after the gear is shift.