A Novel Field Current Estimation Method of the Brushless Synchronous Starter/generator

In the control system of brushless synchronous starter/generator, accurate information about the field current of MG is the paramount to achieve high dynamic and steady-state performance control. However, the traditional field current estimation (FCE) methods rely on the rotor position, when the position sensor fails, the actual field current cannot be obtained. To eliminate the limitation of rotor position and enhance reliability in field current estimation, a novel rotor position signal-free FCE method is presented. Firstly, the expression of estimated rotor currents of main exciter (ME) is derived and the relationship between the field current and estimated rotor current is analyzed. Then, by extracting the corner points of estimated ME rotor currents. the actual field current can be obtained without rotor position. Finally, the experiment result verifies the feasibility and effectiveness of the proposed method.