EV Distance-to-Empty Control at Low State of Charge
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Solution Overview
Problem
Conventional methods for determining the remaining distance to empty (DTE) in electric vehicles become less reliable and cause operator anxiety as the State of Charge (SoC) decreases, leading to rapid drops in estimated range due to varying driving conditions and energy consumption.
Innovation Solution
A method that adjusts the DTE parameter based on the actual distance traveled since it fell below a threshold value, using a control arrangement to set the DTE to a more reliable DTE2 value when SoC is low, ensuring predictable and accurate range estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the DTE parameter is determined based on remaining State of Charge in conventional methods, then the calculation is simple and real-time, but the reliability deteriorates when SoC is low due to rapid decreases in estimated range
Solution Approach 1:
The patent segments the DTE determination process into two distinct methods: a first method using remaining SoC for normal conditions, and a second method using actual distance travelled for low SoC conditions. This segmentation allows each method to be optimized for its specific operating range, improving overall reliability without requiring a completely complex new system.
Solution Approach 2:
The patent dynamically switches between two DTE determination methods based on the current SoC level. When SoC falls below a threshold, the system transitions from the first method (SoC-based) to the second method (actual distance-based), making the determination process adaptive to changing battery conditions and maintaining reliability across different operating states.
2Reliability
If the DTE parameter is based on estimated SoC levels, then real-time estimation is possible, but operator confidence decreases due to rapid range drops at low SoC
Solution Approach 1:
The patent introduces an intermediary mechanism (the second DTE determination method using actual distance travelled) that takes over when the primary method (SoC-based estimation) becomes unreliable at low SoC levels. This intermediary preserves accurate range information by relying on measured actual distance rather than estimated SoC, maintaining operator confidence during critical low-battery conditions.
3Measurement precision
If conventional DTE calculation is used throughout, then the system remains simple, but the DTE parameter becomes inaccurate when energy storage is low
Solution Approach 1:
The patent segments the operational range into two zones: high SoC where simple SoC-based DTE calculation suffices, and low SoC where a more precise but computationally different method (actual distance tracking) is applied. This segmentation achieves high measurement precision across all conditions while keeping the control arrangement manageable by using different approaches for different operating regimes.
Data Source
AI summary
Disclosed are a method and a control arrangement for setting a remaining distance to empty parameter in an electric vehicle, which involve estimating a first remaining distance to empty value at least based on a remaining state of charge of an energy storage. When the first remaining distance to empty value is estimated to be below a distance to empty threshold value, a second remaining distance to empty value is determined at least based on an actual distance travelled since the first remaining distance to empty value was estimated to be below the distance to empty threshold value. The remaining distance to empty parameter is then set at least based on the second remaining distance to empty value. Hereby, the risk of rapid decrease of the distance to empty parameter at low battery charging level is mitigated and the distance to empty parameter will be perceived as correct.