The structure of a permanent magnet generator (PMG) connected with an active front-end rectifier is very popular in the AC-DC architecture. Especially for certain applications like aircraft and vehicles, power density and efficiency is critical. Since the generator and the rectifier can be controlled simultaneously, it would be very desirable to develop a unified control. With this unified control, the boost inductors between the PMG and rectifier is eliminated, which significantly reduce the volume and the weight of the whole system and improve the system power density. Also the system efficiency can be improved with appropriate control strategy. In this thesis, a unified control for the permanent magnet generator and rectifier system is presented. Firstly, the unified model of the PMG and rectifier system is given as the basis to design the control system. Secondly, a unified control method for PMG and rectifier system is introduced. The design procedure for each control loops are presented in detail, including current control loop, voltage control loop, reactive control loop and speed and rotor position estimator loop. Thirdly, the hardware is developed and the experiment is conducted to verify the control strategy. Fourthly, a method to optimize the overall system efficiency by appropriate reactive power distribution is proposed. The two cases when the DC link voltage is flexible and the DC link voltage is fixed are considered. / Master of Science