Abstract :
The variable speed drives market remains a key component and beneficiary of the boom in all aspects of automation and energy saving which arc becoming of ever greater importance throughout the world. The words of Harry Ward Leonard, first uttered on the 18th November 1896 in his paper ʹVolts vs. Ohms speed regulation of electric motorsʹ still hold true; ʹThe operation by means of electric motors of elevators, locomotives, printing presses, travelling cranes, turrets on men-of-\var, pumps, ventilating fans, air compressors, horseless vehicles, and many other electric motor applications too numerous to mention in detail, all involve the desirability of operating an electric motor under perfect and economical control at any desired speed from rest to full speedʹ.
