Decoupling control for aircraft brushless wound-rotor synchronous starter-generator in the starting mode

The main generator (MG) and main exciter (ME) of the aircraft wound-rotor synchronous starter-generator (WRSSG) are electromechanically coupled seriously, which makes the start control for the WRSSG complex in the starting mode. A decoupling control method for the MG and ME of the WRSSG is proposed in this study based on the estimation of the MG field current. In the proposed decoupling method, the MG field current is estimated first and used in the closed-loop excitation control for the ME to make the MG field current meet the MG demand. With the desired field current, the MG is decoupled with the ME and is controlled by using a traditional synchronous motor to start the aircraft engine at maximum torque per ampere. The feasibility and effectiveness of the proposed decoupling control method are verified by experimental results.