EV Charging Path Impedance Detection via Two-Step Voltage Check
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Solution Overview
Problem
Existing methods struggle to accurately distinguish between impedance abnormalities in the charging path and fluctuations in system voltage during vehicle battery charging, leading to potential misidentification of impedance issues.
Innovation Solution
A vehicle system that includes a voltage sensor and control device to execute a two-step process for detecting impedance abnormalities, suspending charging when voltage differences exceed a threshold, and confirming the abnormality after resuming charging to isolate it from system voltage fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single-step voltage difference detection method is used to detect impedance abnormalities, then the detection speed is fast, but the accuracy is poor because it cannot distinguish between impedance abnormalities and system voltage fluctuations
Solution Approach 1:
The detection process is segmented into two distinct steps: a first process that suspends charging when voltage difference exceeds a threshold, and a second process that stops charging only when the voltage difference persists after resumption. This segmentation allows the system to filter out transient system voltage fluctuations while maintaining fast detection response.
Solution Approach 2:
The first process performs a preliminary detection by suspending (not immediately stopping) charging when the voltage threshold is exceeded. This preliminary action allows the system to verify whether the voltage drop is due to impedance abnormality or system fluctuation before taking the final stopping action, thereby improving detection accuracy without significantly increasing overall process complexity.
2Reliability
If charging is immediately stopped when voltage difference exceeds threshold, then the response to impedance abnormality is fast, but false stops occur due to system voltage fluctuations
Solution Approach 1:
The system performs a preliminary suspension of charging in the first process rather than an immediate stop. This allows verification of the voltage drop cause before committing to a charging interruption, reducing false stops due to system fluctuations while maintaining rapid response to genuine impedance abnormalities.
Solution Approach 2:
The second process provides feedback verification by monitoring whether the voltage difference persists after charging resumption. Only when the abnormal voltage condition is confirmed to persist does the system stop charging, ensuring that transient fluctuations do not cause unnecessary charging interruptions and improving overall charging reliability.
3Measurement precision
If a two-step detection process is implemented to improve accuracy, then false detections are reduced, but the detection time increases
Solution Approach 1:
The detection is segmented into a quick first process (suspension) and a confirmation second process (stop). The first process rapidly identifies potential issues, while the second process provides brief verification. This segmentation maintains fast overall detection time while improving accuracy through the structured two-step approach.
Solution Approach 2:
The first process uses a relatively loose threshold for suspension to catch all potential impedance abnormalities, even if some require verification. This partial action ensures no genuine abnormalities are missed, while the second process filters out false positives, achieving high accuracy without excessive detection time.
Data Source
AI summary
A vehicle configured such that an on-board battery is chargeable by receiving electric power from a power supply outside the vehicle includes an inlet, a voltage sensor that detects an input voltage that is a voltage input from the power supply to the inlet, and a control device configured to execute a detection process when connected to the inlet. The detection process includes a first process that suspends charging when a difference between the input voltage before a start of the charging and the input voltage after the start of the charging is equal to or larger than a threshold value, and a second process that stops the charging when a difference between the input voltage during suspension of the charging in the first process and the input voltage after resumption of the charging is equal to or larger than the threshold value.