Fault-Tolerant Soft Starter Control of Induction Motors With Reduced Transient Torque Pulsations

Document Type




Format of Original

12 p.

Publication Date



Institute of Electrical and Electronics Engineers (IEEE)

Source Publication

IEEE Transactions on Energy Conversion

Source ISSN



Fault-tolerant operation of induction motors fed by soft starters when experiencing thyristor/silicon-controlled rectifier open-circuit or short-circuit switch fault is presented in this paper. The present low-cost fault mitigation solution can be easily retrofitted, without significant cost increase, into the existing off-the-shelf three-phase soft starters to enhance the reliability and fault-tolerant capability of such soft starter systems. In the event of either thyristor open-circuit or short-circuit switch fault in any one of the phases, the fault-tolerant soft starters are capable of operating in a two-phase control mode using a novel resilient closed-loop control scheme. The performance resulted from the present fault-tolerant soft starter control has demonstrated reduced motor starting transient torque pulsations as well as reduced motor inrush current magnitude. The present fault-tolerant approach is applicable to any soft starters that control small to large integral horsepower induction motors. Simulation results along with supporting experimental results for a 1.492-kW, 460-V, four-pole, three-phase induction motor are presented here to demonstrate the soundness and effectiveness of the present fault-tolerant approach.


IEEE Transactions on Energy Conversion, Vol. 24, No. 4 (December 2009): 848-859. DOI.