4 Switch Z PWM converters in induction motor drives

Abstract

The thesis presents a general overview of the Z-source converters and the main formulae describing the operation of a Z-source inverter. Several topologies for connecting impedance network to three-phase four-switch inverter are analyzed. It has been shown that some of the topologies are not capable of boost compared to three-phase four-switch inverter without front end impedance network. • A V/f close loop speed control of three phase induction motor fed by a sixswitch Z-source inverter from low to high motor speed. The V/f control is implemented based on Space Vector PWM voltage modulation. The Z-source inverter with controlled peak dc link voltage is used to drive the three phase induction motor. • The four-switch three-phase z-source inverter with induction machine with full load torque ventilator proportional to speed square is described analytically. The algorithm to control the dc boost, split capacitor voltage balance and the ac output voltage of the four-switch three-phase Z-source inverter feed an induction motor drive is proposed. The proposed algorithm has been verified in simulation and experiments. • The improved Z-source inverter with four switches and induction motor drive obtained from the re-arrangement of the Z-Source topology elements presented in chapter three is described with the algorithm to control the dc boost, split capacitor voltage balance and the ac output voltage of the fourswitch three-phase Z-source inverter feed an induction motor drive • The experimental setup of the four switch three phase Z-source inverter for induction motor drive. The hardware system contains a personal computer, a digital control system with a Digital Signal Processor (DSP), a ZSI and other hardware.