Evaluation of the converter topologies suited for integrated motor drives

Currently, standard adjustable speed drives (ASDs) consist of a diode rectifier and a PWM voltage source inverter. The energy stored in the DC-link capacitor is high and heavy iron chokes are needed in order to reduce the peak current through the rectifier diodes and to reduce the input current THD. New regulations to impose better interaction with the grid are expected to force the ASD manufacturers to add major changes to their products in order to improve the input current quality which may additionally provide other benefits such as regulated DC-link voltage and better immunity to unbalanced voltage supply. This paper investigates alternative three-phase ASD topologies for integrated motor drives by discussing the hardware requirements and comparing their performance, size of magnetics and also efficiency, which in this case is important in order to determine their cooling requirements.