Hybrid Engine Starting Control via Load-Based Torque Source Switching
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Solution Overview
Problem
Hybrid-electric powertrains face challenges in starting an internal combustion engine when the battery pack is undercharged or when the electric motor and generator are overloaded, leading to insufficient torque for both equipment operation and engine starting, resulting in unacceptable performance.
Innovation Solution
A control system that determines the load on the electric motor and generator and the state of charge of the high-voltage battery pack to decide whether to use the hybrid-electric system or an exogenous starting device to provide torque for engine starting, ensuring reliable engine cranking by switching to an alternative source when the hybrid-electric system is overloaded or undercharged.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electric motor and generator is used to provide torque to start the internal combustion engine, then the vehicle can maintain hybrid-electric operation, but the starting reliability is insufficient when the battery pack is undercharged or when the electric motor and generator are overloaded
Solution Approach 1:
The control system dynamically switches between two starting modes based on real-time conditions: using the electric motor and generator for starting when battery state of charge and load conditions are favorable, and switching to the exogenous starting device when conditions are unfavorable. This dynamic adaptation resolves the contradiction by making the starting system flexible rather than fixed.
Solution Approach 2:
The control system acts as an intermediary that monitors battery state of charge and load conditions, then selects the appropriate starting source. This intermediary function enables the system to balance between maintaining hybrid-electric operation and ensuring reliable starting under various conditions.
2Adaptability or versatility
If the electric motor and generator provides torque to both power the equipment and start the engine, then the hybrid-electric system can operate autonomously, but the torque available for equipment operation is reduced during engine starting
Solution Approach 1:
The starting function is segmented from the equipment power function. By having a dedicated exogenous starting device available, the system can separate the torque requirements for starting the engine from the torque requirements for powering equipment, allowing the electric motor and generator to focus on equipment power without compromising starting capability.
Solution Approach 2:
The system dynamically determines load conditions and switches between starting sources accordingly. When load conditions indicate sufficient capacity, the electric motor and generator handle both starting and equipment power. When load conditions indicate insufficient capacity, the system switches to the exogenous starting device for engine starting, preserving torque for equipment operation.
3Reliability
If the internal combustion engine is started using the hybrid-electric system, then the battery charge may be depleted, but using an exogenous starting device ensures reliable starting
Solution Approach 1:
The control system continuously monitors battery state of charge and load conditions, using this feedback to determine the appropriate starting source. This feedback mechanism ensures that the electric motor and generator are only used for starting when sufficient battery charge is available, preventing charge depletion while maintaining reliable starting through conditional selection of the exogenous starting device.
Solution Approach 2:
The control system performs preliminary assessment of battery state of charge and load conditions before initiating engine starting. This preliminary action allows the system to select the appropriate starting source in advance, ensuring that starting proceeds reliably without depleting battery charge when conditions are unfavorable.
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
Ensures reliable starting of the internal combustion engine by utilizing the hybrid-electric system when conditions are favorable and switching to an exogenous starting device when necessary, maintaining equipment operation and engine cranking performance.
Implementation Method 1
an electric motor and generator is used to power the starter, or to simply turn the crankshaft of the internal combustion engine
Implementation Method 2
a battery pack powering the electric motor and generator does not have sufficient charge
Data Source
AI summary
A method of starting an internal combustion engine of a vehicle with a hybrid-electric powertrain having an internal combustion engine, a generator, and a high-voltage battery pack, is provided. An internal combustion engine start input signal is received. A load on an electric motor and generator is determined. The internal combustion engine receives torque transmitted from the electric motor and generator when the load on the electric motor and generator is below a predetermined load threshold. The internal combustion engine receives torque from an exogenous starting device when the load on the electric motor and generator is above the predetermined load threshold.