Hl. Hess et al., MODULATION STRATEGIES FOR A NEW SCR-BASED INDUCTION-MOTOR DRIVE SYSTEM WITH A WIDE SPEED RANGE, IEEE transactions on industry applications, 30(6), 1994, pp. 1648-1655
A new SCR-based naturally commutated induction motor drive that provid
es high torque over a wide speed range is presented. Topology is simil
ar to that of certain naturally commutated current source inverters, b
ut modulation techniques and system performance are very different. Tw
o novel switching algorithms are proposed to cover the low-speed and h
igh-speed regimes. Torque ripple is negligible in the low-speed region
. With these two switching techniques, commutation is reliable and ope
ration within peak device voltage stress limits is guaranteed. For ind
uction machine loads, this drive has the torque-speed capability typic
al of a cycloconverter (but with far fewer devices), plus a field weak
ening range that the cycloconverter does not have. Simulation and expe
rimental results are presented.