The detailed model parameters are fundamental to fault characteristics analysis and protection design. Accurate acquisition of inverter controller parameters is essential to analyze the transient characteristics of Inverter Interface Renewable Energy Sources (IIRESs). However, it is challenging to identify the controller parameters using the three-phase current owing to the coupling relationship between the phase-locked loop (PLL) and the inner current loop. Given this, the fault characteristics of the IIRESs considering the non-linear coupling of different control loops is investigated. A fault dynamic response difference-based parameter identification method is proposed. The different time-length response of each controller is utilized for decoupling. The proposed method can identify the parameters of PLL and other controller parameters based on three-phase current and voltage. Simulation and field short-circuit test data are ultimately used to verify the efficacy of the proposed method.