Wiki article · Collection 04

Soft Start

Engineering reference on Soft Start for wireless power system design, integration, and deployment.

6 minArticle 44/50Power Electronics

Soft Start — educational diagram — Fig.: Educational diagram for “Soft Start”.

Soft start gradually increases DC bus voltage or inverter modulation so inrush current into capacitors and resonant tanks stays bounded. For wireless docking, soft start also covers the protocol phase before full power — alignment, ID exchange, then controlled power ramp.

Hard enable into an unloaded resonant tank produces high ringing and can nuisance-trip protection.

01Implementation

PFC soft-start on duty or current limit.
Inverter frequency or phase sweep before full power — common in LLC and WPT literature.
Pre-charge resistors bypassed by relay on DC bus where used.

Soft Start — supporting diagram — Fig.: Supporting illustration for “Soft Start”.

02User experience

Ramp rate balances fleet throughput against stress — too slow extends charge session; too fast repeats failures on weak grid sites. Log ramp failures separately from runtime faults.

03Coordination

BMS must accept inrush during ramp without opening contactor.
Transmitter and receiver ramp together per communication profile.