Soft start optimization using NTC resistors in fault managed power systems

Inrush current limiting methods using Negative Temperature Coefficient (NTC) resistors in power converter circuits are prominent choices in device and system protection schemes. In this paper, a newly developed equipment protection algorithm is introduced, which involves the temporary inclusion of NTC resistors in fault-managed power circuits. The circuit configuration is robust and highly energy-efficient as it maximizes startup capabilities, using the NTC resistor’s self-heat feature to soft start larger loads by fully utilizing the NTC resistor’s energy capacity while still being efficient by bypassing the NTC resistor afterwards. The control algorithm is developed and applied in a real-world Packet Energy Transfer (PET) system. Simulation models were validated with experimental results for a performance study of the soft start circuit.