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

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.