Implementation of variable-speed asynchronous drive fed by current source inverter

Abstract

Vector control of induction motors made these motors widespread in variable-speed applications in comparison with DC motor drives. Applying indirect method of vector-control, the flux sensors would be eliminated and also motor's speed can be controlled as well. Asynchronous motors can be fed by voltage-source or current-source inverters. In high power drives, current-source commutators or inverters are preferred to voltage-source ones. A dc-link current-source is provided by a Buck chopper. The amplitude and frequency of current-source inverter`s output is controlled by asynchronous PWM-CSI method. Between the input terminal of induction motor and the current-source inverter a bank of capacitors is used to eliminate the high order harmonic currents, suppress the spike voltages across the IGBT switches and make guarantee the continuity of motor's current. To implement the current-source inverter, IGBTs high-power switch drivers HCPL316J elements are used. In order to protect the main power switches against transient over voltages, a diode is used in parallel with a snubber circuit and another one in series with power switches. The motor's parameters and also the parameters of PI controllers are optimized by PSO algorithm.