Smart Sensor for Current Leakage Detection for EV Charger Station

Abstract

In the growing electric vehicle market, the efficiency, cost, and safety requirements of charging stations are increasing. Non-isolated DC charging stations use AC/DC non-isolated converters, which provide higher efficiency, lower cost, and greater potential for growth compared to traditional industrial frequency or high frequency AC/DC converters. However, when compared to traditional charging stations that are isolated from the grid, non-isolated DC charging stations have the potential risk of leakage current rising to dangerous levels. Therefore, this paper thoroughly analyzes the negative effects of leakage current in non-isolated charging stations and proposes a fluxgate leakage current sensor suitable for detecting leakage current in non-isolated DC charging stations.

This paper identifies the location of leakage current detection by analyzing the generation mechanism and current path of the AC/DC non-isolated converter. The Jiles-Atherton hysteresis model is established and solved using the fourth-order Lunger Kuta method to accurately describe the B-H mapping relationship. The mathematical model is optimized to consider the effect of temperature. This text presents an analysis of the sensor temperature drift problem and proposes an aerogel thermal insulation scheme to optimize sensor performance under DC charging station operating conditions. The effect of the insulation scheme on the performance of the leakage current sensor is evaluated using ANSYS thermal simulation. Additionally, a MATLAB simulation model is used to analyze the effect of relative capacitance on the accuracy of the fluxgate sensor. These research results support the improvement of charging station safety and performance.

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