Hybrid Vehicle Engine Stop Control for Battery Protection
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Solution Overview
Problem
Hybrid vehicles do not effectively manage power transmission and reception when stopping the engine, leading to excessive battery degradation due to increased motion energy consumption by the engine and motor generators, and existing control methods fail to adequately prevent overdischarge, affecting battery lifetime.
Innovation Solution
A hybrid vehicle system that includes a control mechanism with a target drive power setting, calculating, and limiting means, along with a transition prohibiting means to manage engine state transitions based on battery state, preventing excessive power consumption and overdischarge by prohibiting engine stoppage when power consumption exceeds a calculated threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine is stopped to improve fuel efficiency, then fuel consumption is reduced, but the motion energy of the engine and motor generator increases causing excessive power consumption and battery degradation
Solution Approach 1:
The patent implements dynamic control of engine stoppage decisions based on real-time vehicle conditions. The control unit continuously monitors vehicle speed, acceleration requests, and battery state of charge, adjusting engine stoppage permission dynamically. At higher vehicle speeds or when acceleration is requested, engine stoppage is prohibited to avoid excessive stopping power consumption. This dynamic adaptation resolves the contradiction by allowing engine stoppage only when conditions are favorable.
Solution Approach 2:
The system employs feedback control by monitoring the state of charge of the battery and using this information to determine whether engine stoppage should be permitted. When the battery state of charge is low, the system receives feedback that stopping power consumption would be excessive, and consequently prohibits engine stoppage. This feedback mechanism ensures that fuel efficiency improvements do not come at the cost of battery degradation.
2Use of energy by moving object
If the engine is stopped to improve fuel efficiency, then fuel consumption is reduced, but battery degradation is accelerated due to excessive power consumption during engine stoppage
Solution Approach 1:
The control unit receives feedback regarding the state of charge of the battery and uses this information to make informed decisions about engine stoppage permission. When the battery state of charge indicates limited capacity, the system prohibits engine stoppage to prevent excessive power consumption that would accelerate battery degradation. This feedback-based decision-making protects battery reliability while still allowing fuel efficiency improvements when conditions are appropriate.
Solution Approach 2:
The system dynamically adjusts engine stoppage permission based on real-time battery state of charge conditions. Rather than a fixed stoppage strategy, the control adapts to current battery conditions, permitting stoppage only when the battery has sufficient charge to handle the stopping power consumption without accelerated degradation. This dynamic approach balances fuel efficiency gains with battery lifetime protection.
3Reliability
If a vehicle speed threshold is set to prohibit intermittent engine operation, then battery input is protected, but the control performance is insufficient when regeneration operation is performed
Solution Approach 1:
The control unit implements a universal decision-making mechanism that handles multiple operating conditions through a single integrated control logic. Rather than separate control strategies for different operations, the system uses a unified approach that considers vehicle speed, acceleration requests, and battery state of charge together to determine engine stoppage permission. This multi-functional control achieves both battery protection and adequate control performance across all operating modes including regeneration.
Solution Approach 2:
The system uses comprehensive feedback from multiple sensors including vehicle speed, acceleration requests, and battery state of charge to make engine stoppage decisions. This multi-parameter feedback mechanism provides sufficient control performance by considering the complete operational context, not just vehicle speed. The feedback-based control adapts to regeneration operations and other special conditions while maintaining battery protection.
Data Source
AI summary
In a hybrid vehicle, a controller includes a target drive power setting device which sets a target drive power requested for the running of the vehicle, a target drive power calculator which calculates target drive power from the target drive power set by the target drive power setting device and the vehicle speed detected by a vehicle speed detector, an output limiter which limits the amount of power obtained from an electricity storer based on the state of the electricity storer, and a transition prohibitor which prohibits the transition of an engine to a stopped state when the power consumed for the transition of the engine from an operational state to a stopped state exceeds a value obtained by subtracting the target drive power calculated by the target drive power setting device from the output limit value set by the output limiter.