Mauricio B. R. Correa

Combining Model-Based and Heuristic Techniques for Fast Tracking the Maximum-Power Point of Photovoltaic Systems

This paper proposes a technique for accelerating the convergence to the maximum power point of photovoltaic (PV) systems based on the model obtained from manufacturers generator data. The influence of the temperature over the PV array performance is considered, and no measurement of solar radiation is required. Knowledge of the load model and expensive sensor circuitry are not necessary. The tracking speed is much faster than nonmodel-based techniques at the expense of an increase in the computational complexity. Simulation and experimental results are presented and demonstrate the feasibility of the proposed solution.

Vector and scalar modulation for six-phase voltage source inverters

This paper presents an improved PWM control of six-phase voltage source inverters supplying a split-phase induction motors. The approach is based on a space vector modulation and designed to improve the performance of the system in terms of THD and DC bus utilization. Several scalar and vectorial patterns are proposed and evaluated by using the total harmonic distortion as a figure of merit. Simulation and experimental results are presented to demonstrate the feasibility of the proposed solutions.

Six-phase AC drive system with reduced common-mode voltage

This paper investigates a six-phase machine drive configuration that permits to reduce the common-mode voltage. The drive system consists of a six-phase inverter feeding a six-phase induction motor, which is adequate to develop a high power system with current rating restrictions. Several pulsewidth modulation techniques for generating gate signals to command the power switches of the six-phase inverter are presented. The proposed strategies permits to reduce either the mean value or the instantaneous value of the common-mode voltage. Simulation and experimental results demonstrates the feasibility of the proposed solution.

Field oriented control of a single-phase induction motor drive

This paper investigates the vector control of a single-phase induction motor drive to implement low cost systems for low power applications. The static power converter side is implemented using a single-phase rectifier cascaded with a four-switch inverter (FSI). The vector control is based on the field orientation concepts that were adapted for this type of machine. Simulation and experimental results are provided to illustrate the operation of the systems.

Using the model of the solar cell for determining the maximum power point of photovoltaic systems

This paper proposes a technique for accelerating the convergence to the maximum power point of photovoltaic (PV) systems based on the model obtained from manufacturers generator data. The influence of the temperature over the PV array performance is considered, and no measurement of solar radiation is required. No knowledge of the load model and no expensive sensor circuitry are necessary. The tracking speed is much faster than non model-based techniques at the expenses of an increase in the computational complexity. Simulation and experimental results are presented and demonstrate the feasibility of the proposed solution.

Single-phase induction motor drives systems

This paper discusses high- and low-performance single-phase motor drive systems. The drive system configurations provide power factor control and improved electromagnetic torque. Several high-performance control strategies have been adapted to be used with the single-phase machine. A low-performance and low-cost strategy that does not require removal of the start-up and running capacitors of the single-phase machine is also proposed. Simulation and experimental results are provided to illustrate the operation of the proposed drive systems.

Compensation of DC link oscillation in single-phase VSI and CSI converters for photovoltaic grid connection

In this work it is presented a technique to reduce DC link oscillation in Voltage Source Inverter (VSI) or Current Source Inverter (CSI) that operates connected to a single phase grid. That oscillation can be responsible for losses or malfunctioning of the DC sources (photovoltaic panels or batteries). It is also may cause efficiency reduction of photovoltaic generators. The oscillation reduction can be achieved by adding two power switches and a passive energy storage element to the converter topology. Details about design and control strategies for both topologies, which has demonstrated performance improvements, when compared with others solutions, are presented. Simulation and experimental results are provided to validate the theoretical approach and to evaluate the topologies performance and quantify energy efficiency gain.

A Simplified Induction Machine Model to Study Rotor Broken Bar Effects and for Detection

Rotor broken bar initially do not cause an induction motor to fail, but it can have serious secondary effects. Thus comprehension of rotor broken bar effects, and detection methods is useful for the safety of the motor drive. Effort of researchers ensure complex models with capability to describe broken bars effects, but these models do not help detect broken bar. Use of variable speed induction motor drives allow to exploit model based detection method. This paper proposes the use of a simply model that allows to evaluate effects of rotor broken bars and that can be exploited for fault detection or even for control. Detailed analysis of the model and results from simulation are presented to validate the proposed approach.

Digital current control of unbalanced three-phase power electronic systems

This paper examines the control of unbalanced three-phase three-wire power electronic systems. The control strategy proposed is derived from a double controller scheme that employs one controller for the positive sequence and another for the negative sequence. The controller is implemented in a microcomputer-based system at the stationary reference frame. The simulation and experimental results demonstrate the validity of the proposed methodology.

High performance photovoltaic pumping system using induction motor

Photovoltaic pumping is one of the most interesting applications for distributed energy generation. Despite that, cost still a concern, when compared with others energy resources. Therefore, efficiency improvement can be seen as one way for cost reduction. Use of maximum power point tracker allows generating more energy with the same amount of panels, which means more energy per panel. Nevertheless, the whole power processing has more than panels. It also includes converters, inverter, electrical motor, pump and batteries, which store energy for further use during solar outrage. The aim of this paper is to show how to achieve an effective photovoltaic pumping system without batteries. In this solution the role of batteries are replaced by fluid storage and, steady state operation depends on the amount of available power. Evaluations of all system devices, for each processed power level, allow to conclude about their efficiency and to clarify how they can be controlled to make the whole system operates at maximum efficiency level. Experimental results help to show how a photovoltaic pumping system can be improved in terms of efficiency.