Abstract: In this paper, a controller “black/grey box” identification method for a direct-drive wind turbine generator（WTG） based on port measured impedances is proposed to overcome the modeling difficulties caused by the control “black/grey box” problem of wind power converters. First, the analytical impedance models of the DC port of the machine-side converter and the AC port of the grid-side converter of a permanent magnet synchronous generator（PMSG）-based WTG are derived and validated under different control modes. Second, the parameter sensitivities of the DC and AC port impedances are analyzed to demonstrate the identifiability of the controller parameters, and the features of the DC port impedance under different control modes are extracted based on the parameter sensitivity. On this basis, a “black box” control mode identification method is proposed for a PMSG-based WTG based on frequency-domain impedance feature matching. Further, a “grey box” control parameters identification method, in which all control parameters are accurately identified by minimizing the sum of squares of the differences between the measured impedance and the theoretical impedance over the studied frequency range based on the damped least squares algorithm, is proposed for a PMSG-based WTG based on frequency-domain impedance characteristic consistency. Finally, the effectiveness of the proposed method is verified through a case study.