DEVELOPMENT AND PERFORMANCE INVESTIGATION OF MICROCOMPUTER CONTROLLED . KRAMER DRIVE USING PWM INVERTER

Abstract

There is a growing demand for precise and reliable variable speed drive. The problem in selecting an adjustable speed drive for a particular application is to choose the system that can most economically provide the required range of speed or torque or position control with desired accuracy and fastness of response. For high power rati ng, vari abl e speed applications slip ring induction motor has been very popular, with newly available solid state power devices, there is renewed interest in this slip ring induction motor. The availability of rotor terminals introduces new possibilities of wide range of speed control. This gives rise to slip recovery scheme. Kramer drive C slip recovery scheme for sub synchronous speed ) using static devices is popular with cement industry and rolling mills. But the principal disadvantage of the conventional. Kramer drive using static devices is its low power factor, displacement factor particularly at reduced speeds. The reactive power consumption of line commutated inverter is largely responsible for the low power factor of a drive. The present work is aicored to improve power factor of Krasner drive by using a PWM Inverter and i.rt.vestigating its performance. Th8 PWM control technique is implemented in such a way that both active and reactive powers are returned back to three phase supply source. As a result over all power factor i S improved significantly even in the low speed range.