Power Loss Reduction Control for Doubly Salient Electromagnetic Machine Based on Adaptive Currents Coordination Allocation

In traditional doubly salient electromagnetic machine (DSEM) driving system, the unregulated rated field current brings in large power loss, especially under the less rated power conditions. To address this problem, this paper proposes an online currents coordinated allocation strategy. Firstly, the mathematical expression of DSEM power loss is fitted based on the finite element model, and the optimal coordinated field current expression is achieved. Then, based on the field current mapping, an easy-implemented torque observer is designed to identify the load torque to search for the optimal coordinated field and armature currents. On these bases, the traversal algorithm is proposed to be applied for adaptively finding the optimal field current rather than solving the 6th equation. In further, considering that the optimal field current varies with multiple time-varying parameters, system parameters sensitivity analysis is carried out, and the extended kalman filter (EKF) and the forgetting factor recursive least squares (FFRLS) methods are respectively employed to identify the armature and field winding resistances which are strongly correlated with the coordinated currents. Afterwards, to suppress the parameters identification errors caused by the DSEM semi-square current waveform in commutation process, a cascaded data optimization processor is put forward. The experiments on a 12/8-pole DSEM validate the correctness and effectiveness of the proposed methods under multiple operating conditions.