T.M. Oliveira

Fault tolerant control of five-phase AC motor drive

This paper investigates the voltage and current control of a five-phase induction motor drive under fault conditions. The control strategies allow for continuous and disturbance free-operation of the drive without any additional hardware connections at the occurrence of complete loss of one or two legs of the inverter or motor phases. The control presented here is oriented to open loop torque control strategies (e.g., Volts/Hz control), but can be very useful for direct torque control or even field oriented control strategies. A complete analysis of voltage and current controls are presented. Experimental and simulation results demonstrate the validity of the proposed systems.

Reduced Switch Count Multiple Three-Phase AC Machine Drive Systems

In this paper, two three-phase ac drive systems with reduced number of components, named configurations and , are investigated. Configuration uses multiple two-leg voltage source inverters in which all inverters share an extra-leg. Configuration also employs multiple two-leg inverters but in this case the inverters share the midpoint of a capacitor bank in the dc-link, instead. These configurations are compared to configuration that employs multiple three-leg inverters. The main characteristics of the machine drive systems are presented together with selected experimental results that demonstrate the feasibility of the proposed configurations.

Single-Phase AC–DC–AC Three-Level Three-Leg Converter

In this paper, a three-level three-leg ac-dc-ac converter for single-phase applications is investigated. The operating principles and control strategies for the topology are presented. It is shown that dc-link voltage balancing and its reduction are important objectives in the system design. The proposed pulsewidth modulation (PWM) strategy permits the dc-link capacitor voltage balance and also its reduction. The three-level converter is compared to the two-level converter in terms of rms switch currents, harmonic distortion, losses, and costs. Experimental and simulation results are presented to validate the theoretical studies.

AC/AC converters with a reduced number of switches

This paper proposes two reduced switch count AC/AC converters. The proposed topologies allow single-phase to three-phase and three-phase to three-phase power conversion. The converters provide bidirectional power flow and power factor control. The pulse-width modulation techniques and the control strategies for providing unity power factor operation are investigated. Experimental and simulated results are presented.

Vector modeling and control of unbalanced electrical systems

In this paper a vector modeling approach is employed to represent the transient and steady-state behavior of unbalanced three-phase (three wires), unbalanced two-phase and single-phase systems containing PWM converters. In the case of the three-phase system, it is decomposed on dq components, by using an appropriate coordinate transformation, and then the vector model is obtained. While in the case of the single-phase system, a fictitious second single-phase system is introduced to obtain the vector model. From the vector model, two vector controllers in the direct and indirect synchronous reference frames are defined. The digital version of this controller in the stationary reference frame is also presented. Simulations and experimental results are presented for a VSI power converter system.

Component minimized drive systems for multi-machine applications

This paper examine two component minimized multiple three-phase AC motor drive systems. Configuration A uses multiple two-leg inverter topologies in which all inverters share a extra-leg. Configuration B also uses multiple two-leg inverter topologies but in this case inverters share the midpoint of a capacitor bank in the DC-link. The main characteristics of the drive systems are presented together with experimental results.

Eliminating the common-mode voltage in AC drive systems using a four-phase machine

This paper investigates the utilization of a machine drive configuration that permits elimination of the common-mode voltage. The drive system employs a four-phase inverter and a four-phase induction motor. A complete analytical model of the four-phase induction machine is presented. The pulse-width modulation technique for generating the gate signals for the power switches of the four-phase inverter is also presented. Simulation and experimental results are presented to demonstrate the feasibility of the proposed solution.

DC-Link Single-Phase to Single-Phase Half-Bridge Converter Operating with Reduced Capacitor Current and AC Capacitor Power

This paper proposes a control technique to reduce the ac fundamental capacitor currents and the ac capacitor power of the single-phase half-bridge converter The technique can be used for applications where the load frequency is equal to the input frequency. Experimental and simulated results are presented.

Reversible six-phase AC motor drive systems with reduced switch count

This work presents four reduced switch count six-phase AC motor drives. The configurations were conceived to operate without the use of the boost inductor filter. The drive systems provide both bidirectional power flow and power factor control. The work presents the operating principles and control strategies of the topologies. Experimental and simulation results are presented.

A reduced switch count three-phase AC motor drive

This paper proposes a reduced switch count three-phase AC motor drive system. The proposed drive system uses a five-leg converter topology, composed of ten switches and provides bidirectional power flow and power factor control. The pulse-width modulation technique for the five-leg converter is presented and the implementation of unity power factor control is investigated. Experimental and simulated results are presented.