Research on Control Strategies and Temperature Field of Loss-of-Excitation Fault-Tolerant DSEM Based on Different Converters Under Normal/Fault-Tolerant Operating Conditions

To improve the fault-tolerant operation ability of the doubly salient electro-magnetic machine (DSEM) in case of loss-of-excitation, the turns of DSEM winding are designed accordingly. However, the increase of armature winding self-inductance causes the current to rise slowly during commutation, which affects the torque output. In addition, the temperature distribution of the fault-tolerant DSEM will change greatly during normal and fault-tolerant operation. Considering these problems, a comparative analysis is performed on the DSEM to examine the dynamic response of the phase current during the commutation process based on different converters, including the bridge converter and asymmetric half-bridge converter. The field-circuit joint simulation model is built to analyze the performance under normal/fault-tolerant operation. The temperature field model is established to analyze the temperature field of the loss-of-excitation fault-tolerant DSEM under different operating modes. Finally, a prototype is made and tested. The results indicate that the half-cycle control strategy is worth reconsidering. This strategy not only can effectively suppress the torque ripple of fault-tolerant DSEM, but also does not need to change the control strategy of normal and demagnetized fault-tolerant operation. In addition, the copper loss and temperature rise of the motor winding are reduced in this strategy.