Active Current Trajectory Control (ACTC) – for Hot Swap, Capacitor Discharge, Circuit Breaker and Current Shaping

Abstract:
Hot swap controllers are used in a wide range of industrial applications to mitigate problems during hot swap events. This paper aims to introduce a new algorithm - active current trajectory control (ACTC) which could improve modern hot swap controllers. This new algorithm fundamentally tracks the voltage/current trajectory across the safe operation area (SOA) diagram of the device and actively controls the gate of the switch in the linear region to limit the current and control the shape according to the SOA boundary lines. Furthermore, the algorithm de-rates the SOA boundary in real time depending on the operating conditions. Therefore, the device never operates outside of SOA, in a sense it never fails due to in-rush. The developed demonstration board works for a wide range of MOSFETs and the proposed hot swap algorithm was tested with both Si-based MOSFET for 48V rail and SiC MOSFETs for 400V rails. The control has also been extended to other applications, such as safe capacitor discharge and current shaping.