Hybrid Vehicle Engine Loss Torque Control for Saturated Battery
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Solution Overview
Problem
In hybrid vehicles, regenerative braking is limited when the battery is fully charged, leading to missed opportunities for energy recovery and unpredictable braking behavior, which affects driving pleasure and safety, and existing solutions either disrupt the driver's expectations or accelerate battery aging.
Innovation Solution
A method that controls the deceleration phase by supplying traction torque solely with the electric motor when the torque setpoint is positive, and both regenerative and loss torque when the condition of energy recovery saturation is activated, with the heat engine starting and providing loss torque to match the driver's braking intent, while ensuring the battery remains below maximum charge limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If regenerative braking is used when the accumulator is at maximum state of charge, then energy recovery opportunity is lost, but if friction braking system is used instead, then driving pleasure and braking control are reduced
Solution Approach 1:
The system changes the operating parameters of the heat engine by controlling fuel injection quantity and timing to generate variable loss torque. When the accumulator is saturated, the engine operates in a high-resistance mode with reduced fuel injection to provide maximum loss torque, effectively replacing regenerative braking capability while maintaining predictable braking behavior for the driver
Solution Approach 2:
The heat engine acts as an intermediary component between the saturated accumulator and the braking system. Instead of directly switching from regenerative to friction braking, the heat engine provides a transitional loss torque that bridges the gap, maintaining braking control and driving pleasure while the accumulator remains saturated
2Power
If the heat engine is started to provide loss torque when the accumulator is saturated, then braking capacity is maintained, but the driver cannot anticipate which brake will be applied
Solution Approach 1:
The control system continuously monitors the accumulator state of charge and vehicle deceleration rate, providing feedback to determine when to activate the heat engine for loss torque. This feedback mechanism ensures the engine is activated only when regenerative braking is saturated, making the braking behavior predictable and understandable to the driver
Solution Approach 2:
The system dynamically adjusts the braking torque distribution between the friction braking system and the heat engine loss torque based on real-time conditions. The heat engine's loss torque is modulated to match the driver's braking intent, creating a dynamic but predictable braking response that maintains driver anticipation
3Productivity
If the starting assistance device is used to discharge the accumulator, then regenerative braking opportunities are increased, but the heat engine operates unexpectedly by the driver
Solution Approach 1:
Instead of discharging the accumulator through starting assistance (which would prevent future regenerative braking), the system takes preliminary action by activating the heat engine to provide loss torque only when the accumulator is saturated. This prevents the need for unnecessary discharges while maintaining braking capability, avoiding the counterproductive effect of reducing future regenerative opportunities
4Productivity
If unnecessary discharge of the electric accumulator is imposed, then regenerative braking opportunities are increased, but battery aging is accelerated
Solution Approach 1:
The heat engine provides self-service by generating loss torque on-demand when the accumulator is saturated, eliminating the need for forced discharges through starting assistance. This self-service mechanism maintains the accumulator charge level within optimal ranges, preventing unnecessary aging while preserving regenerative braking opportunities
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 enhances driving pleasure and safety by providing consistent braking performance, increasing braking capacity, and preventing unnecessary battery discharge, making the vehicle's behavior more understandable to the driver and reducing battery aging.
Implementation Method 1
An electric machine able to supply a traction torque to the wheels and to supply a recovering torque of kinetic energy during a deceleration of the vehicle
Implementation Method 2
a first engine, generally a heat engine, capable of supplying a loss torque to the wheels
Implementation Method 3
engine braking is rather abrupt
Data Source
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AI summary
The invention relates to a method for controlling a deceleration phase of a hybrid vehicle powertrain comprising a combustion engine (11) and a second motor (19). The invention proposes a method during a deceleration phase comprising a step in which the combustion engine (11) supplies loss torque to the wheels in addition to regenerative torque from the second motor (19) when energy recovery is saturated. The method is applicable to any type of hybrid vehicle, whether combustion/electric or combustion/hydraulic.