The Impact of Circuit Variables on the Starting Performance of Field-Aligned Starting

Field-aligned starting (FAS) is a new technique for starting three-phase cage induction motors on either three- or single-phase supply lines with minimal inrush currents. FAS generates a high impulse like torque to start the motor that is independent of the mains supply, before connecting the already spinning motor to the mains supply. In contrast to conventional starting techniques, FAS imposes higher than normal/rated voltage and current conditions on the machine at starting, and as such, the transient performance of FAS operated motors is complex in nature and largely governed by a number of key circuit variables, the values of which are critical for an efficient and economical design of FAS. A detailed insight into the influence of these key parameters on transient performance during startup is essential to avoid time consuming and inefficient trial and error design methods currently utilized in FAS designs. This paper addresses this need through the investigation of both the functionality and the extent of impact of the key variables on the starting performance of FAS. A transient model is utilized, and both experimental and simulated results suggest that, for a given set of circuit components, the proper selection of variable values is critical to achieve the best possible performance at startup.