HV Pre-Charge Impedance Analysis for Short Circuit Diagnosis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current systems fail to effectively diagnose high voltage short circuits and impedance issues in vehicles during the pre-charge mode, which can lead to safety risks and component damage due to the complexity of detecting low-impedance faults and the need for rapid detection of short circuits.
Innovation Solution
An apparatus and method utilizing a controller coupled to the high voltage power net that measures voltage and current variations during pre-charge, performs short circuit diagnosis by comparing against threshold curves, and conducts impedance analysis to identify faults, ensuring safe operation and preventing battery discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional monitoring methods are used during pre-charge mode, then the system structure remains simple, but the ability to detect short circuits and low-impedance faults is insufficient
Solution Approach 1:
The system performs impedance analysis and short circuit diagnosis during the pre-charge mode, which occurs before the main contactor closes and full power is applied. This preliminary detection allows the system to identify faults before they can cause damage or safety issues, improving reliability without requiring additional complex monitoring equipment during full operation
Solution Approach 2:
The system uses the pre-charge resistor and pre-charge contactor as intermediary elements to enable fault detection. By measuring voltage and current through these existing pre-charge components, the system can detect short circuits and low-impedance faults without directly exposing the main battery or requiring additional measurement equipment in the high-voltage circuit
2Measurement precision
If impedance analysis is performed during pre-charge mode, then short circuit detection accuracy is improved, but the pre-charge operation time increases
Solution Approach 1:
The impedance analysis and short circuit diagnosis are performed continuously throughout the pre-charge mode operation. Rather than adding a separate detection step that would extend the pre-charge time, the system utilizes the entire pre-charge duration to continuously monitor for faults, maintaining detection accuracy while minimizing additional time loss
Solution Approach 2:
The system performs impedance analysis at multiple discrete voltage points during pre-charge (e.g., at 10V, 20V, 30V intervals) rather than requiring complete charging to full voltage. This partial action approach provides sufficient detection accuracy to identify short circuits and low-impedance faults without requiring the full pre-charge duration, thereby reducing the time penalty
3Measurement precision
If multiple measurements are taken during pre-charge, then impedance analysis accuracy is improved, but the processing complexity increases
Solution Approach 1:
The controller uses its existing computational resources and measurement capabilities to perform the impedance analysis. Rather than requiring additional dedicated measurement equipment or complex external processing systems, the system leverages the microcontroller's built-in analog-to-digital converters and processing power to calculate impedance values from the measured voltage and current data during pre-charge
Data Source
AI summary
In at least one embodiment, an apparatus for performing a high voltage (HV) short circuit diagnosis and an impedance analysis for a vehicle is provided. The apparatus includes a controller configured to measure a first voltage associated with a battery and a first current that varies based on a HV power net during the pre-charge operation and to perform the short circuit diagnosis based on the first voltage and the first current. The controller is further configured to determine a difference between the first voltage and a pre-charge voltage across one of a capacitor and the HV power net and to measure a second current based at least on the difference. The controller is further configured to perform the impedance analysis for the vehicle based on the second current.