EV Distance-to-Empty Control at Low State of Charge
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for determining the remaining distance an electric vehicle can travel before needing to recharge, known as the Distance to Empty (DTE), become less reliable at low State of Charge (SoC), causing unnecessary stress for operators due to rapid drops in estimated range.
Innovation Solution
A method that adjusts the DTE parameter by calculating a second remaining distance based on actual travel distance since the DTE fell below a threshold, ensuring a more accurate and predictable estimate, even at low SoC levels, and reduces maximum available power when DTE reaches zero to conserve energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the DTE parameter is determined based on remaining State of Charge at low SoC levels, then the calculation is simple and continuous, but the reliability and accuracy of the DTE parameter deteriorates due to rapid decreases
Solution Approach 1:
The patent segments the DTE determination process into two distinct methods based on SoC threshold: (1) When SoC is above the threshold, DTE is determined based on remaining energy and consumption rate; (2) When SoC is below the threshold, DTE is determined based on actual distance travelled. This segmentation resolves the contradiction by applying the appropriate method for each operating condition, ensuring reliability at low SoC while maintaining simplicity when SoC is adequate.
Solution Approach 2:
The patent introduces an intermediary parameter - the SoC threshold - that mediates between the simple energy-based calculation and the more reliable distance-based calculation. This threshold acts as a trigger that switches between determination methods, ensuring that the simple method is used when conditions permit, but switching to the reliable distance-based method when SoC drops below the threshold, thus resolving the reliability-complexity contradiction.
2Reliability
If the DTE parameter is determined based on actual distance travelled when below threshold, then the reliability improves, but the device complexity increases due to additional tracking requirements
Solution Approach 1:
The system segments the operational range into two zones: high SoC zone using energy-based calculation and low SoC zone using distance-based calculation. This segmentation allows the use of the more reliable distance-based method only when necessary (below threshold), rather than continuously, thereby improving reliability at critical moments while minimizing the overall complexity burden.
Solution Approach 2:
The system leverages existing vehicle data infrastructure (odometer, position sensors) that already track distance travelled for other purposes. By utilizing these existing self-service data streams, the patent implements reliable DTE determination at low SoC without requiring additional specialized sensors or complex tracking hardware, thus improving reliability while limiting complexity increase.
3Measurement precision
If the DTE parameter shows rapid decreases at low SoC, then the calculation reflects actual energy depletion, but the operator experiences unnecessary stress and reduced confidence
Solution Approach 1:
Instead of allowing the DTE parameter to decrease rapidly based on energy depletion calculations at low SoC (which causes operator stress), the patent inverts the approach by making DTE increase or stabilize based on actual distance travelled. This inversion prioritizes operator confidence and ease of operation over strict energy depletion precision in the critical low-SoC regime, resolving the contradiction between measurement precision and operator well-being.
4Productivity
If the vehicle allows operation down to zero SoC, then the available range is maximized, but the risk of battery damage and loss of reliability increases
Solution Approach 1:
The system performs preliminary action by switching from energy-based to distance-based DTE determination before the battery is fully depleted. By detecting when SoC falls below the threshold and switching methods proactively, the system prepares for the approaching depletion point, allowing operators to plan recharging before critical levels are reached, thus maximizing usable range while protecting against over-discharge damage.
Solution Approach 2:
The patent implements beforehand cushioning by maintaining a protective buffer through the threshold-based method switching. The distance-based determination method acts as a cushion that prevents harsh, stress-inducing DTE drops and provides a more predictable operational profile near depletion, cushioning both the operator experience and the battery from the stress of rapid energy depletion and zero-SoC operation.
Data Source
Figure 1
Figure 2a
Figure 2b
AI summary
The invention relates to a method performed by a control arrangement for setting a remaining Distance to Empty parameter in an electric vehicle, wherein the control arrangement is configured to estimate a first remaining Distance to Empty value at least based on a remaining State of Charge of the vehicle's energy storage. The method comprises when the first remaining Distance to Empty value is estimated to be below a Distance to Empty threshold value determining a second remaining Distance to Empty value 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 method further comprises setting the remaining Distance to Empty parameter 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 which means that unnecessary stress is avoided when low State of Charge of the vehicle's energy storage is reached. The invention also relates to a control arrangement, a vehicle comprising the control arrangement, a computer program, and a computer-readable medium.