Battery knowledge · High-voltage and functional safety

Inrush current

The brief current peak when a circuit is first energised, before its capacitors have charged or its magnetic parts have settled. Connected straight to a pack, an inverter’s empty DC-link capacitors would draw thousands of amperes, so a pre-charge circuit brings them to about 95% of pack voltage before the main contactor closes.

Also called
inrush, surge current, switch-on surge

Example

High-voltage and functional safety: an example situation

Normal-operation current limits do not demonstrate correct contactor behavior under a welded-contact or sensor fault.

Read Inrush current alongside Blanking delay in this context. A short window during which a protection or diagnostic input is deliberately ignored, so that an expected transient — the inrush when contactors close, a load step, switching noise — does not trip it. It spans microseconds in a gate driver’s desaturation protection to tens of milliseconds or more around contactor closure; too long a window delays reaction to a real fault.

Use in Lemonergy

Relate protection to faults, detection and response.

This is a reference concept. No executable Lemonergy block has been verified for this term.

References & further reading

Further reading on this topic

These sources provide broader context; they are not presented as citations for every statement in this entry.

  1. ISO 26262-1:2018 — Road vehicles — Functional safety — Part 1: Vocabulary

    International Organization for Standardization · 2018

    Topic background · Scope and terminology of automotive electrical/electronic functional safety. The catalogue is not the full standard.