Hybrid Drive Transition Control Using Pre-Coupling Generator Torque
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Solution Overview
Problem
Hybrid vehicles experience a reverse movement and discomfort during the transition from electric to hybrid operation due to the time required for the internal combustion engine to start and couple, leading to a temporary power mismatch between the electric drive and the engine.
Innovation Solution
A temporary series hybrid drive is implemented by actuating the generator before the internal combustion engine is fully coupled, using generator power in conjunction with electrical storage unit power to provide increased torque, smoothing the transition and ensuring greater traction power availability before full coupling, and adjusting power distribution to maintain efficient energy balance post-coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the internal combustion engine is started to allow hybrid operation, then hybrid power is available, but reverse movement occurs due to the time delay of approximately 1 second required for engine start-up
Solution Approach 1:
The generator is actuated in advance during the engine start-up phase to generate electrical power that is immediately supplied to the traction motor. This preliminary action compensates for the power gap during the 1-second delay, preventing reverse movement and maintaining driving comfort during the transition from electric to hybrid operation.
2Power
If the internal combustion engine is started, then hybrid operation is enabled, but a further reverse movement results due to the coupling of the started internal combustion engine
Solution Approach 1:
The generator is actuated before the engine is fully coupled to the output, generating electrical power that compensates for the torque fluctuations during coupling. This preliminary power generation prevents the second reverse movement that would otherwise occur when the engine couples to the output shaft.
Solution Approach 2:
The generator acts as an intermediary power source during the engine coupling process. By providing electrical power to the traction motor during this transition, the generator mediates the torque fluctuations and prevents reverse movement, smoothing the power delivery throughout the coupling process.
3Force
If the generator is actuated before full coupling, then temporary series hybrid drive provides greater torque, but electrical power distribution must be precisely managed
Solution Approach 1:
The control device continuously monitors the engine's coupling state and the electrical storage unit's charge level, using this feedback to dynamically adjust the generator's power output. This ensures optimal torque is provided during the transition while preventing overloading of the electrical storage unit, managing the complexity through intelligent control.
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 method enhances driving comfort by ensuring a smoother transition from electric to hybrid operation, providing greater torque and maintaining efficient energy use, preventing overloading and overheating of the electrical storage unit, and allowing for a gradual increase in traction power without sudden jumps.
Implementation Method 1
the generator (for example a starter generator) is set into a generator mode, in which this generator power is generated
Implementation Method 2
power that is fed from an electrical storage unit, such as an accumulator
Data Source
AI summary
A method for changing from electrical operation to hybrid operation in a vehicle hybrid drive is provided. The method includes detecting an increase in a target traction power and starting the internal combustion engine. When the internal combustion engine starts, the method includes outputting a positive torque by generating an increasing generator power. The generator power is used together with an electrical power of a storage unit for generating electrical traction power. The generator power is generated while the internal combustion engine is not yet fully coupled to an output. The method includes fully coupling the internal combustion engine to the output after the generation of the increasing generator power has begun. After the internal combustion engine has been fully coupled, the method includes reducing the electrical power of the storage unit to a non-positive value and adjusting the generator power in accordance with a predetermined energy balance.