Performance of an SCR-inverter-based commutatorless series motor with loadcommutation and unaided startup capability

This paper examines the starting and variable-speed performance of a silico n-controlled-rectifier-based commuta-torless series motor with special emph asis on the commutating process for the operation of a self-controlled sync hronous machine in the load-commutated mode, unassisted by extra components or special techniques, even at very low speeds, including starting. A dyna mic simulation of the drive, in which the field winding of the synchronous machine is located in the dc link has been presented, the results of which are validated by comparison with those of an experimental prototype, The in fluence of the damper windings on the commutation process and in the suppre ssion of the voltage spikes so generated, and in reducing overlap times, ha s also been studied. A phasor-diagram-based steady-state analysis predicts the parameters of suitable machines for such an operation. The inherent ser ies characteristics of this drive, its high power factor, and self-starting capability will find applications in large-power traction drives, flywheel energy storage systems, centrifugal pumps, etc.