Four-quadrant Fault-tolerant Control Strategy for Doubly Salient Electro-magnetic Motor Under Loss of Excitation
Jun Luo, Lei Xiong, Keqiong Chen, Yi Lu, Hongjun ShiIntroduction:
Excitation failures can occur in the Doubly Salient Electromagnetic Machine (DSEM) due to overheating and aging during long-term operation. However, such excitation faults pose a severe threat to DSEMs that rely on excitation torque for operation, causing the motor to lose driving capability in motoring mode and power generation capability in braking mode, thereby preventing it from fulfilling the requirements of four-quadrant operation
Methods:
To meet the four-quadrant operation requirements of DSEM under excitation loss, this paper proposes a four-quadrant fault-tolerant control strategy. First, based on the torque output characteristics of the DSEM during forward operation, a Two-Cycle Twelve-State Control (TCTSC) strategy is proposed for the forward motoring mode in the first quadrant and the reverse braking mode in the second quadrant. Second, based on the torque output characteristics of the DSEM during braking operation, a Two-Cycle Six-State Control (TCSSC) strategy is proposed for the reverse motoring mode in the third quadrant and the forward braking mode in the fourth quadrant. Finally, by combining the polarity of the change rate of reference speed with the direction of the feedback speed, the motoring and braking control are switched
Results:
This four-quadrant operating system enables four-quadrant operation of the DSEM and reduces torque pulsation during operation.
Discussion:
The proposed quadrant-switching method enables four-quadrant operation of the DSEM. Under the two proposed control strategies, torque ripple during operation can be reduced, and the output torque can be fully utilized based on the variation characteristics of inductance. The proposed strategies provide an effective method for achieving four-quadrant operation of the DSEM and suppressing torque ripple
Conclusion:
Simulation results verified that the proposed four-quadrant system can achieve fourquadrant fault-tolerant operation with low torque ripple and smooth operation when switching between different quadrants for the DSEM under excitation loss.