Comparing Devices for Concurrent Measurement of AC Current and DC Injection during Electric Vehicle Charging

Abstract

Widespread adoption of electric vehicles (EVs) requires additional safety countermeasures to prevent DC injection from EVs into the AC grid via Electric Vehicle Supply Equipment (EVSE). Moreover, for energy purchase, and even more so for vehicle-to-grid (V2G) services, the EVSE must conduct high precision bidirectional power and energy measurements. This paper introduces operating principles, structure, performance, and cost comparison of three current sensing technologies—current transformer, shunt and fluxgate—for metering and protection within an EVSE, concluding with recommendations among those sensors for the most beneficial applications concerning EV charging.

Design of Fluxgate Current Sensor Based on Magnetization Residence Times and Neural Networks

“…Based on the Taylor expansion, in the vicinity of zero, the linear approximation arcsin(x) ≈ x is applicable. Consequently, when (17) can be approximately reformulated as follows:…”

“…These vehicles rely heavily on precise and accurate current measurements for essential functions such as battery management, motor control, autonomous driving, and charging systems [11][12][13][14][15]. Fluxgate current sensors, known for their high precision, wide bandwidth (including DC), and galvanic isolation, are particularly favored in this context [16][17][18].These sensors have become a focal point in research aimed at enhancing performance. An innovative approach involves using a 20 µm-thick Fe 15 Ni 46 Co 39 film with low coercivity and high Curie temperature, placed on a Cu ring to serve as a magnetic core [19].…”