A Peak-Current-Limit Soft Start Control Method With Short-Circuit Tolerance for CLLC Converter Based on Time-Domain Model

The CLLC converter has been widely adopted in electric vehicle (EV) chargers due to its advantages of high efficiency, high power density, and low electromagnetic interference (EMI). However, in outdoor applications such as fast-charging stations, harsh environmental conditions pose significant challenges to the CLLC converter, particularly in the form of short-circuit faults. To address this issue, a short-circuit-tolerant soft start control method for the CLLC resonant converter is proposed in this paper. Based on time-domain model, the minimum limit of the switching frequency is adaptively adjusted according to the voltage gain, enabling limitation of the peak resonant current. Finally, experimental results obtained from a 1-kW prototype demonstrate that the proposed control method effectively limits the start-up current under various load conditions and exhibits short-circuit tolerance during both start-up and steady-state operation. The start-up time is reduced by 20%-72% compared to existing methods with the same hardware configuration and maximum resonant current.