Sensorless Control Strategy of Electrical Variable Transmission Machines for Wind Energy Conversion Systems

This paper focuses on the control for the dual power flow wind energy conversion system (DPF-WECS) based on the permanent magnet electrical variable transmission (PM-EVT) machine. The PM-EVT machine can be considered as two permanent magnet synchronous machines (PMSMs) by ignoring the magnetic field coupling between the inner rotor and stator windings. For the DPF-WECS, the speed of the inner rotor should be controlled precisely to generate the constant voltage and constant frequency electricity. However, the rotor position of the inner PMSM composed of the inner rotor and outer rotor is difficult to be measured exactly due to the rotational stator and rotor. Thus the inner PMSM is hardly to be controlled using vector control strategy with the measured rotor position. In this paper, a sensorless control strategy based on the model reference adaptive system (MRAS) for the PM-EVT machines with double layer permanent magnet outer rotor for the DPF-WECS is proposed and evaluated by simulation. The effectiveness of proposed control strategy is verified by experimental results.