Hybrid Engine Start-Stop Control via SOC Ranges
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Solution Overview
Problem
Constant cycling of engines in hybrid electric vehicles to maintain battery state of charge leads to unnecessary wear and reduced fuel economy due to frequent auto-starts and auto-stops below and above certain thresholds.
Innovation Solution
A controller manages engine start and stop conditions by running the engine until a target battery state of charge is reached, with predetermined ranges to optimize engine operation, preventing unnecessary starts and stops, and inhibiting auto-starts below a minimum threshold to conserve battery energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine is constantly cycled to maintain battery state of charge, then the battery's state of charge is maintained, but engine wear increases and fuel economy decreases
Solution Approach 1:
The patent changes the control parameters by introducing multiple SOC ranges (first range: 30-60%, second range: 10-30%) with different engine control strategies. When SOC is in the first range, the engine runs until SOC reaches a target or start condition ceases. When SOC is in the second range, the engine runs until SOC achieves the target. This parameter-based differentiation reduces unnecessary engine cycling while maintaining battery charge levels.
2Reliability
If the engine is constantly cycled to maintain battery state of charge, then the battery's state of charge is maintained, but fuel economy decreases
Solution Approach 1:
The patent implements parameter changes by establishing different SOC thresholds and ranges that trigger different engine control behaviors. By setting the first predetermined range at 30-60% and the second at 10-30%, with a target SOC above these ranges, the system optimizes fuel consumption by avoiding unnecessary engine starts when SOC is adequate, while ensuring engine operation when SOC drops into critical ranges.
3Reliability
If the controller runs the engine until SOC achieves target in the second predetermined range, then SOC is maintained above minimum threshold, but engine operates longer potentially reducing fuel efficiency
Solution Approach 1:
The patent applies preliminary action by proactively running the engine when SOC enters the second predetermined range (10-30%) to recharge the battery before the SOC drops to critical low levels. This preliminary charging action prevents the need for more extensive engine operation later and avoids potential engine stall conditions, optimizing both reliability and fuel efficiency.
Data Source
AI summary
A controller may be configured to respond to an engine start condition that occurs while an SOC of the battery is within a first predetermined range by running an engine until first occurrence of the start condition ceasing or the SOC achieving a target. The controller may further be configured to respond to an engine start condition that occurs while the SOC is within a second predetermined range less than the first by running the engine until the SOC achieves the target.