Cursino B. Jacobina

Improved Dead-Time Compensation for Sinusoidal PWM Inverters Operating at High Switching Frequencies

This paper proposes a technique to compensate the effects of dead time in sinusoidal pulsewidth-modulated voltage-source inverters. The compensation is implemented by adjusting the switching frequency to avoid unfeasible pulsewidths of the gating signals, as well as to minimize the total harmonic distortion of the inverter output voltage. The technique can be used at any switching frequency, but the best results are obtained in the high-frequency range. The experimental results of the proposed technique that is applied in a three-phase induction motor drive system are presented.

Pulsewidth Modulation Strategies

This article reviews the nonsinusoidal CPWM and SVPWM techniques and deals with the three possibilities of calculation of pulsewidths after the addition of a zero-sequence signal. A general algorithm is proposed and adapted for dealing with the control of the three-level NPC inverter and also the Z-source converter. Experimental results corroborate the proposed technique.

Application of single-phase to three-phase converter motor drive systems with IGBT dual module losses reduction

This paper aims to apply a universal filter configuration to supply a three-phase motor from the single-phase grid, in this case the motor must be supplied with the same frequency of grid. The initial hypothesis consider that is possible to minimize the converters losses through the variation of motor voltage phase and through selection of an appropriate transformer. To reduce the IGBT dual module losses means to reduce the operational cost of the system. The initial investment of this configuration is very attractive for treating of a converter that works in shunt, in other words, only a part of the load power flows through the converter. Analysis in steady state has been realized, as well. Experimental results are showed to demonstrate the theoretical studied.

Detection and compensation of switch faults in a three level inverter

This paper deals with open and short-circuit switch faults in a three-level inverter feeding a three-phsse induction motor. It also investigates the fault compensation via topologies that are able to maintain the system operation for a period of time. Simulated and experimental results verify the feasibility of proposed strategies.

The Transformerless Single-Phase Universal Active Power Filter for Harmonic and Reactive Power Compensation

This paper presents a universal active filter for harmonic and reactive power compensation for single-phase systems applications. The proposed system is a combination of parallel and series active filters without transformer. It is suitable for applications where size and weight are critical factors. The model of the system is derived and it is shown that the circulating current observed in the proposed active filter is an important quantity that must be controlled. A complete control system, including pulse-width modulation (PWM) techniques, is developed. Comparisons between the structures are made from weighted total harmonic distortion (WTHD). The steady-state analysis is also presented in order to demonstrate the possibility to obtain an optimum voltage angle reducing the current amplitude of both series and parallel converters and, consequently, the total losses of the system. Simulated and experimental results validate the theoretical considerations.

Single-Phase to Three-Phase Power Converters: State of the Art

Single-phase to three-phase conversion using power electronics converters is a well-known technology, especially when the configurations and control strategies already established in the technical literature are considered. Regarding the configurations conceived over the years, it can be observed two main tendencies: 1) configurations with a reduced number of components; and 2) configurations with an increased number of components. The search for topologies with a reduced number of components was the trend over a long period of time. This can be, in part, explained by the high cost of the power switch when compared to the capacitor used in the dc-link bus. Then, the converter leg was sometimes substituted for the midpoint capacitor. However, as far as the price of the semiconductor was going down, such tendency has been changed, and now the configurations with an increased number of components do appear as an interesting option, especially in terms of reliability, efficiency, and distortions improvement. A comprehensive review of the two possibilities (reduced and increased number of components) has been considered in this paper. Also, the single-phase to three-phase ac-ac direct conversion configurations and those which aim to reduce the dc-link voltage fluctuation have been included. The goal of this paper is to provide a complete range on the status of single-phase to three-phase power conversion technologies to professionals and researchers interested in this topic.

Single-Phase to Three-Phase Drive System Using Two Parallel Single-Phase Rectifiers

This paper proposes a single-phase to three-phase drive system composed of two parallel single-phase rectifiers, a three-phase inverter, and an induction motor. The proposed topology permits to reduce the rectifier switch currents, the harmonic distortion at the input converter side, and presents improvements on the fault tolerance characteristics. Even with the increase in the number of switches, the total energy loss of the proposed system may be lower than that of a conventional one. The model of the system is derived, and it is shown that the reduction of circulating current is an important objective in the system design. A suitable control strategy, including the pulsewidth modulation technique (PWM), is developed. Experimental results are presented as well.

Single-Phase to Three-Phase Universal Active Power Filter

In this paper, a universal active power filter is proposed for harmonic and reactive power compensation in the single-phase to three-phase systems. The proposed configuration solves a typical problem found in remote (or rural) applications, where only a single-phase grid is available and there is a demand to supply three-phase loads. A suitable control strategy is presented to regulate the load voltage, the power factor, and to minimize the voltage and current harmonics simultaneously. Simulated and experimental results are also presented.

Dynamic Voltage Restorer Based on Three-Phase Inverters Cascaded Through an Open-End Winding Transformer

This paper investigates a dynamic voltage restorer (DVR) composed of two conventional three-phase inverters series cascaded through an open-end winding (OEW) transformer, denominated here DVR-OEW. The DVR-OEW operating with either equal or different dc-link voltages is examined. The proposed topology aims to regulate the voltage at the load side in the case of voltage sags/swells, distortion, or unbalance at the grid voltage. A suitable control strategy is developed, including space-vector analysis, level-shifted PWM and its equivalent optimized single-carrier PWM, as well as the operating principles and characteristics of the DVR. Comparisons among the DVR-OEW and conventional configurations, including a neutral-point clamped converter-based DVR, are furnished. The main advantages of the DVR-OEW compared to the conventional topologies lie on: 1) reduced harmonic distortion, 2) reduced converter losses, and 3) reduced voltage rating of the power switches. Simulated and experimental results are presented to validate the theoretical studies.

Nested Multilevel Topologies

This paper proposes multilevel topologies based on the concept of nested arrangement. Such topologies are called nested multilevel converters, since the central point of the legs are connected at the same point, with the external legs involving the internal ones. Nested configurations present advantages as compared to the equivalent NPC topologies in terms of reduced number of diodes and consequently higher efficiency. In addition to proposing a new family of power electronics converters, this paper presents an optimized pulse width modulation strategy that allows synthesizing voltage waveforms with higher quality, a losses comparison with the NPC topology, and a general comparison with other topologies proposed in the technical literature. Simulated and experimental results are presented to validate the theoretical expectations.