Hybrid Vehicle Controller Regenerative Braking Neutral Coasting
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Solution Overview
Problem
Hybrid electric vehicle energy efficiency drops when regenerative-power generation is prohibited during coasting with the transmission in neutral position.
Innovation Solution
A hybrid electric vehicle control device that manages regenerative-power generation by allowing it during coasting with the transmission in neutral through a controller that adjusts torque requests and braking forces, ensuring energy efficiency is maintained by blending regenerative and friction braking torques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If regenerative-power generation is prohibited during coasting with transmission in neutral, then the vehicle operator's intended coasting behavior is respected and transmission wear is reduced, but vehicle energy efficiency drops
Solution Approach 1:
The control device dynamically adjusts the transmission gear stick position based on driving conditions. When the vehicle is coasting and the accelerator pedal is released, the control device automatically shifts the transmission from neutral to an engaged gear position, enabling regenerative-power generation while maintaining coasting behavior. This dynamic adjustment resolves the contradiction by allowing energy recovery without preventing the driver's intended coasting operation.
Solution Approach 2:
The system changes the transmission gear state parameter from neutral to engaged based on detected coasting conditions. When the control device detects that the accelerator pedal is released and the vehicle is coasting, it changes the transmission gear stick position parameter to enable regenerative braking, thereby improving energy efficiency while preserving the coasting operation characteristics.
2Loss of energy
If regenerative-power generation is permitted during coasting with transmission in neutral, then vehicle energy efficiency is improved, but braking response difference between EV and HEV modes increases
Solution Approach 1:
The control device dynamically adjusts the braking torque distribution between friction brakes and regenerative brakes based on the current operating mode. When in HEV mode with transmission engaged during coasting, the system activates regenerative braking and adjusts friction brake application accordingly. This dynamic torque distribution maintains consistent braking response characteristics across different modes while enabling energy recovery.
Solution Approach 2:
The control device continuously monitors the operating mode (EV or HEV) and adjusts the braking torque allocation based on feedback from the mode detection. When HEV mode is detected during coasting, the system enables regenerative braking and modulates friction brake application to maintain consistent overall braking response, thereby resolving the contradiction between energy efficiency and braking response consistency.
3Loss of energy
If the transmission gear stick is automatically shifted to enable regenerative braking, then energy efficiency is maintained, but transmission control complexity increases
Solution Approach 1:
The control device integrates multiple functions into a single control unit that manages both transmission gear stick positioning and braking torque distribution. This multi-functional controller automatically adjusts the transmission gear position based on coasting detection and simultaneously manages the braking system, thereby enabling regenerative braking without requiring separate complex control systems for transmission and braking management.
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 a drop in vehicle energy efficiency by permitting regenerative-power generation during coasting with the transmission in neutral, enhancing overall energy management and reducing the difference in braking response between electric vehicle and hybrid electric vehicle modes.
Implementation Method 1
a motor generator that acts as a drive source for the vehicle wheels or as a generator for regenerative-power generation
Implementation Method 2
friction brake force component depending on pedal travel of the brake pedal
Data Source
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AI summary
[Task] To provide a hybrid electric vehicle control having good effectiveness in preventing the vehicle energy efficiency from falling even though the regenerative-power generation is prohibited during coasting: [Solution] A hybrid electric vehicle control, includes: a transmission 4 switchable between different gear stages in response to a change in position at which a gear stick 40 is placed, an engine 2 for driving vehicle wheels 6 through the transmission 4, a motor generator 3 positioned between the transmission 4 and the vehicle wheels 6, and a controller 10. The controller10 is programmed to deny regenerative-power generation permission to prohibit regenerative-power generation via the motor generator 3 during coasting with the transmission 4 in neutral, but it grants the regenerative-power generation permission in response to operator input to a brake pedal 92 even during coasting with the transmission in neutral to permit regenerative-power generation via the motor generator 3 over the period of operator input to the brake pedal 92 during coasting with the transmission 4 in neutral.