Hybrid Vehicle SOC Control via Variable Thresholds
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Solution Overview
Problem
Hybrid vehicles face reduced fuel efficiency and increased load on the engine due to excessive alternation between engine start and stop, necessitating improved state of charge (SOC) control strategies that reflect driver intention and road conditions.
Innovation Solution
A driving control method for hybrid vehicles that uses variable SOC ranges and power distribution strategies based on vehicle speed and road gradient, including a data map to determine optimal driving modes and adjust boundary values, preventing excessive engine starting and stopping, and ensuring battery charge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine frequently alternates between start and stop to optimize fuel efficiency, then fuel consumption is reduced, but the load on the engine and clutch increases and reliability decreases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the SOC threshold values based on vehicle operating conditions such as vehicle speed and road gradient. When the vehicle is stationary or moving at very low speeds, the threshold for engine restart is raised (e.g., from 40% to 60% SOC), preventing unnecessary engine starts and reducing mechanical wear while still maintaining fuel efficiency benefits during normal operation.
2Use of energy by moving object
If the SOC threshold is lowered to allow more engine stops, then fuel efficiency improves, but the engine may not start reliably when needed
Solution Approach 1:
The patent implements dynamics by making the SOC threshold values variable rather than fixed. The control system continuously monitors vehicle speed and road gradient, and adjusts the SOC thresholds dynamically accordingly. This allows the system to lower thresholds when conditions permit (improving fuel efficiency) while raising them when reliability concerns arise (such as at very low speeds), thus resolving the contradiction between fuel efficiency and start reliability.
3Reliability
If the SOC threshold is raised to ensure engine availability, then reliability improves, but fuel efficiency deteriorates due to excessive engine operation
Solution Approach 1:
The patent applies parameter changes by adjusting SOC thresholds based on vehicle operating conditions. During normal driving conditions, lower SOC thresholds are used to minimize engine operation and maximize fuel efficiency. However, when the vehicle is stationary or moving at very low speeds, the thresholds are raised to ensure engine availability, thus resolving the contradiction between reliability and fuel efficiency through context-dependent parameter adjustment.
4Device complexity
If a fixed SOC threshold strategy is used, then control simplicity is maintained, but adaptability to different driving conditions deteriorates
Solution Approach 1:
The patent implements dynamics by transitioning from a fixed SOC threshold strategy to a dynamic one that adapts to vehicle operating conditions. The control system monitors vehicle speed and road gradient in real-time and adjusts the SOC thresholds accordingly. This maintains relatively simple control logic while significantly improving adaptability to different driving conditions, thus resolving the contradiction between control simplicity and adaptability.
Data Source
AI summary
A driving control method for a hybrid vehicle has state of charge (SOC) ranges including a high SOC range, an intermediate SOC range and a low SOC range, and a plurality of power distribution strategies corresponding to the respective SOC ranges. The driving control method controls the hybrid vehicle using a power distribution strategy corresponding to an SOC range to which a current SOC of the hybrid vehicle belongs. When a speed of the hybrid vehicle is high or low and is outside a predetermined range, boundary values of the intermediate SOC range and the low SOC range among the SOC ranges are increased.