Torque Distribution Control for Hybrid Vehicle Energy Efficiency
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Solution Overview
Problem
Current torque distribution methods for hybrid electric vehicles do not achieve global optimization, leading to suboptimal energy efficiency and reduced service life of engine and electric motor, with energy consumption not minimized across all driving conditions.
Innovation Solution
A method that collects and analyzes driving data to derive typical driving conditions, employing global optimization for torque distribution between the engine and electric motor, considering engine and motor efficiencies, battery SOC management, and NVH performance, with rule-based distribution adapting to various conditions and using offline BSFC maps to optimize torque allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If instantaneous torque distribution is used based on current working conditions, then response speed is improved, but global energy efficiency optimization deteriorates
Solution Approach 1:
The system pre-calculates and stores optimal torque distribution strategies in a lookup table during the design phase, covering various driving conditions and battery SOC levels. During actual operation, the controller simply queries this pre-computed table based on current conditions, achieving both fast response and global optimization without real-time complex calculations
Solution Approach 2:
The torque distribution strategy dynamically adapts to changing driving conditions and battery SOC levels by selecting appropriate pre-computed strategies from the lookup table. The system transitions between different operating modes (engine-only, motor-assist, regenerative braking) based on real-time conditions while maintaining globally optimal energy efficiency
2Use of energy by moving object
If engine operates at high efficient conditions only, then energy efficiency is improved, but adaptability to various driving conditions deteriorates
Solution Approach 1:
The hybrid powertrain system is designed with multi-functionality to handle diverse driving conditions. The engine can operate in high-efficiency regions for steady-state cruising, while the electric motor provides assist torque during acceleration, enables regenerative braking during deceleration, and ensures operation when the engine is in inefficient regions, making the system universally adaptable to all driving scenarios
Solution Approach 2:
The system changes operating parameters dynamically by adjusting the torque split between engine and motor based on driving conditions and battery SOC. The controller modifies engine torque output, motor torque contribution, and battery charge/discharge rates to maintain optimal energy efficiency across varying operating conditions
3Device complexity
If torque distribution considers only current conditions, then control simplicity is improved, but service life extension deteriorates
Solution Approach 1:
The system continuously monitors battery SOC, driving conditions, and component operating states, using this feedback to query the pre-computed lookup table and adjust torque distribution accordingly. This closed-loop control ensures components operate within optimal ranges to extend service life while maintaining simple real-time implementation through table lookup
Data Source
AI summary
A torque distribution method for an engine and a motor of an energy-efficient hybrid electric vehicle comprises the following steps: providing an offline specific fuel consumption map of the engine in all operating states; enabling the engine and motor to respond to the required torque T during travelling together, the motor and the engine working in cooperation at the same rotational speed so as to achieve the optimal working efficiency; acquiring a current state of charge (SOC) of the vehicle battery, and distributing the engine torque T and the motor torque T according to the following situation: if the SOC is greater than a first preset value, entering a first distribution mode; if the SOC is less than a second preset value, enter a second distribution mode; and otherwise, maintaining the current working state. The method can fully utilize the performance advantage of the engine and that of the motor, so that the system works at high efficiency all the time, thereby decreasing the energy consumption of the vehicle, greatly reducing harmful emission, and facilitating energy conservation and environmental protection.