How can inrush current detection equipment accurately capture transient and high-amplitude surge currents in AC electric vehicle power supply systems?

Publish Time: 2026-01-29

With the widespread adoption of electric vehicles, AC charging stations have become an important part of urban infrastructure. However, under complex operating conditions such as frequent start-stop cycles, sudden load changes, and grid fluctuations, power supply circuits are prone to generating transient surge currents—these surges can last as short as microseconds, but their peak values can reach 5–10 times the rated current. These surges can not only damage the internal electronic components of the charging station and the on-board charger (OBC), but also cause grid harmonic pollution or even power outages. Deploying high-precision inrush current detection equipment is crucial to ensuring the safe and stable operation of AC electric vehicle power supply systems.

1. High-speed sampling and wide dynamic range: the foundation for capturing transient details

Surge currents have steep rise edges and short durations. The system immediately triggers high-speed waveform recording, and the inrush current detection equipment retrospectively saves data from the milliseconds prior to triggering. This mechanism ensures complete capture of the surge's initiation process, providing crucial evidence for analyzing its causes.

2. Anti-interference Signal Processing: Extracting Real Surge Features from Noise

The operating environment of inrush current detection equipment is subject to severe electromagnetic interference—switching power supplies, PWM control, CAN communication, etc., all generate high-frequency noise. The detection equipment employs dual noise reduction through hardware filtering and digital signal processing: the front end uses shielded cables and differential inputs to suppress common-mode interference; the back end uses wavelet transform, moving average, or adaptive filtering algorithms to effectively separate real surge signals from high-frequency glitches. Especially during the instant of electric vehicle startup, the charging of the rectifier capacitor in the on-board OBC generates a surge-like "magnetizing inrush current," which the system must distinguish through waveform feature recognition to avoid false alarms.

3. Multi-parameter Synchronous Recording and Event Tracing

Accurate capture refers not only to current amplitude but also to contextual information such as time, phase, and voltage status. High-end equipment can simultaneously collect three-phase voltage, current, power factor, and charging pile communication status, and add high-precision timestamps. When a trip or fault occurs, maintenance personnel can replay the complete event sequence to determine whether the surge was caused by a lightning strike on the grid side, the start/stop of nearby equipment, or an malfunction of a specific electric vehicle, greatly improving fault location efficiency.

4. Compliance with Standards and System Integration: A Closed Loop from Monitoring to Protection

Detection equipment is not only used for post-event analysis but can also be integrated into the charging pile protection logic. Once a surge of a dangerous level is identified, the system can trigger a relay to cut off the output or send a pause charging command to the vehicle, forming a "monitoring-judgment-response" closed loop to proactively prevent equipment damage.

In AC electric vehicle power supply systems, inrush current detection equipment has evolved from a passive recording tool to an active safety guardian. Through high-speed sampling, intelligent triggering, anti-interference algorithms, and system-level integration, it can accurately "freeze" the complete picture of transient surges within a microsecond-level time window. This not only provides data support for equipment reliability but also lays the technological foundation for building a safe, intelligent, and resilient future charging network.