Hybrid Vehicle Battery Charging Torque Control Strategy
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Solution Overview
Problem
Hybrid electric vehicles face challenges in efficiently managing the charging of batteries using internal combustion engines, particularly in balancing engine load and torque demands while optimizing fuel economy and engine efficiency across varying driving conditions.
Innovation Solution
A control strategy that utilizes a traction motor connected to both the engine and transmission, adjusting charging torque based on battery state and engine speed to reduce engine load, and dynamically allocating torque between the engine and motor to meet driver demands, including generating positive torque to assist the engine when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the motor operates to generate charging torque based on battery state of charge, then the battery charging efficiency is improved, but the engine load increases
Solution Approach 1:
The system dynamically adjusts the charging torque generated by the motor based on real-time engine speed feedback. When engine speed drops below the threshold, the controller reduces or eliminates charging torque to prevent excessive engine loading, thereby resolving the contradiction between charging efficiency and engine load through dynamic parameter adjustment
2Loss of energy
If the engine speed decreases below threshold while charging, then the engine efficiency is improved, but the available torque for vehicle propulsion decreases
Solution Approach 1:
The controller continuously monitors engine speed and uses this feedback to adjust motor torque in real-time. When engine speed falls below the threshold during charging operation, the system automatically modifies motor torque to maintain engine speed within the efficient operating range, ensuring both engine efficiency and adequate torque availability
3Power
If the motor generates positive torque to assist the engine, then the driver demanded torque is satisfied, but the battery energy consumption increases
Solution Approach 1:
The system changes the motor torque parameter from negative (charging mode) to positive (assist mode) based on real-time operating conditions. When engine torque alone cannot satisfy driver demand, the controller adjusts motor torque to provide assistance, optimizing the balance between power delivery and energy consumption through parameter adaptation
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 fuel efficiency by optimizing engine operation, reducing fuel consumption, and improving overall vehicle performance by leveraging the strengths of both internal combustion engines and electric motors, while also promoting battery charging through regenerative braking.
Implementation Method 1
The motor can be used in either a motoring mode in which energy from the battery is used to supplement the engine power or in a generating mode in which the motor converts mechanical energy into electrical energy which is stored in the battery
Data Source
AI summary
A control system for a modular hybrid electric vehicle operates an internal combustion engine at a torque level above the driver demanded torque improving the engine's efficiency. A traction motor driveably connected to the engine is operated at a torque level such that the combined torque satisfies the driver demand. The traction motor torque is limited to avoid inefficient combinations of speed and torque at which the motor is inefficient. During idle operation, the traction motor is operated at a torque determined from a battery state of charge and the engine is operated to maintain a predetermined speed. If the engine speed drops below a threshold, motor torque is adjusted to reduce the load on the engine to avoid stalling.