José Antenor Pomilio

Energy Management Fuzzy Logic Supervisory for Electric Vehicle Power Supplies System

This paper introduces an energy management strategy based on fuzzy logic supervisory for road electric vehicle, combining a fuel cell power source and two energy storage devices, i.e., batteries and ultracapacitors. The control strategy is designed to achieve the high-efficiency operation region of the individual power source and to regulate current and voltage at peak and average power demand, without compromising the performance and efficiency of the overall system. A multiple-input power electronic converter makes the interface among generator, energy storage devices, and the voltage dc-link bus. Classical regulators implement the control loops of each input of the converter. The supervisory system coordinates the power flows among the power sources and the load. The paper is mainly focused on the fuzzy logic supervisory for energy management of a specific power electronic converter control algorithm. Nevertheless, the proposed system can be easily adapted to other converters arrangements or to distributed generation applications. Simulation and experimental results on a 3-kW prototype prove that the fuzzy logic is a suitable energy management control strategy.

Induction-generator-based system providing regulated voltage with constant frequency

The electrical characteristics of an isolated induction-generator-based system are improved through the association with a voltage-source pulsewidth modulation (PWM) inverter. The electronic converter allows the achievement of a better system behavior in many aspects: voltage regulation, frequency stabilization, and reactive power compensation. The system operation strategy consists of maintaining constant synchronous frequency at the induction generator via an association with a PWM inverter. The system power balance and the generator voltage regulation may be accomplished by two different means: through the rotor speed regulation, or by sending part of the energy stored in the inverter DC side to the grid through a single-phase line, in case the rotor speed is not regulated and a single-phase grid connection is available. The obtained results demonstrated the system is stable, robust, and an effective source of regulated three-phase voltages.

Control Strategy for Battery-Ultracapacitor Hybrid Energy Storage System

Hybrid energy storage systems have been investigated with the objective of improving the storage of electrical energy. In these systems, two (or more) energy sources work together to create a superior device in comparison with a single source. In particular, batteries and ultracapacitors have complementary characteristics that make them attractive for a hybrid energy storage system. But the result of this combination is fundamentally related to how the sources are interconnect and controlled. The present work reviews the advantages of battery-ultracapacitor hybridization, some existing solutions to coordinate the power flow, and proposes a new control strategy, designed for the improvement of performance and energy efficiency, while also extending the battery life. The control strategy uses classical controllers and provides good results with low computational cost. Experimental results are presented.

Characterization and Compensation of Harmonics and Reactive Power of Residential and Commercial Loads

This paper uses data obtained from laboratory measurements of typical home appliances to verify whether these nonlinear loads behave similar to current or voltage-type harmonic sources. Based on the measurements and additional simulations, it is stated that domestic and commercial electronic loads behave essentially like harmonic voltage sources. This behavior helps to explain why reactive shunt compensators and filters may even increase the harmonic current content in the feeders. Additionally, based on field measurements in a residential low-voltage distribution secondary, the share between linear and nonlinear loads, as well as the prevailing kind of their nonlinearity is analyzed. The measurements, made just before and after the installation of a capacitor bank, confirm that the use of shunt compensation increases both voltage and current distortion in the feeder

Self-excited induction generator controlled by a VS-PWM bi-directional converter for rural applications

This paper is concerned with an application of a three-phase cage induction machine as a self-excited hydroturbine driven generator connected to the AC side of a voltage source PWM (VS-PWM) bi-directional converter. The generator is supposed to be driven by a low-head unregulated shaft hydraulic turbine. Under this condition, the range of turbine speed variation is narrower than for wind turbine driven generators. Frequency and voltage at the AC load are regulated by the action of the PWM converter. The proposed system is intended to be applied in rural plants as a low-cost source of high quality AC sinusoidal voltage with regulated frequency and amplitude. Simulation results are based on the /spl alpha//spl beta//spl gamma/ stationary reference frame model of the induction machine using the PSpice(R) program. The experimental results report the system behavior with balanced and unbalanced, linear and nonlinear loads. The generator also presents satisfactory behavior at the start-up of an induction motor set at 66% of the system rated power.

A Line-Interactive Single-Phase to Three-Phase Converter System

This paper describes a line-interactive single-phase to three-phase converter. A typical application is in rural areas supplied by a single-wire with earth return system. The traditional objective of feeding a three-phase induction motor is not anymore the main concern for such conversion. Due to the evolution of the farm technology, some of the local loads (as electronic power converters, computers, communication equipments, etc) require high power quality that is intended as sinusoidal, symmetrical, and balanced three-phase voltage. Additionally, to maximize the power from the feeder, the system provides a unity power factor to the grid. A three-phase voltage source inverter-pulsewidth modulation converter is used for this purpose. The power converter processes a fraction of the load power and the energy necessary to regulate the dc link voltage. As it does not need to supply active power, it is not necessary to have a source at the dc side. However, if island mode operation is needed, a dc source must be available at the dc link to supply the load. The control strategy, design criteria, and experimental results are presented

Interaction between EMI filter and power factor preregulators with average current control: analysis and design considerations

The effects of a nonnegligible source impedance, due to the presence of an input EMI filter, on the stability of power factor preregulators with average current control are analyzed by using a state space averaged model. The modeling allows to derive a simple expression for the loop gain in terms of the converter current loop gain. The overall system stability is studied for boost, Cuk and SEPIC PFP topologies. Based on this model, a simple modification of the standard current control loop is proposed which increases the converter robustness. Comparison between model forecasts and experimental measurements is carried out using two prototypes: one based on the boost topology and the other based on the SEPIC topology both rated at 600 W. Finally, the model accuracy is investigated with measurements at different current loop bandwidths.

Modeling and Control Design of the Interleaved Double Dual Boost Converter

The interleaved double dual boost (IDDB) is a non-isolated step-up dc-dc converter capable of high voltage gain and suitable to high-power applications. In this paper, the modeling and control design of this converter, valid for an arbitrary number of phases, is presented. The developed approach is then applied to a six-phase IDDB, and experimental results are obtained with a prototype operating with an input voltage of 60 V, an output voltage of 360 V, and with a nominal output power of 2.2 kW. The applications of this converter include electrical vehicles and renewable energy conversion.

Induction generator based system providing regulated voltage with constant frequency

A PWM voltage-source inverter is used in order to improve the electrical characteristics of an isolated induction generator. The electronic converter allows achievement of a better system behavior in many aspects: voltage regulation, frequeney stabilization and reactive power compensation. The PWM inverter DC voltage is the control variable of the generator speed governor, therefore the system power balance and the generator voltage regulation is accomplished by the DC voltage control, which is exerted by the speed governor. Both simulation and experimental results demonstrated that the system is stable, robust and an effective source of regulated three-phase voltages.

Three-Phase Low-Frequency Commutation Inverter for Renewable Energy Systems

The connection of distributed power sources with the utility grid generally needs an electronic power converter for processing the locally generated power and injecting current into the system. If the source provides a dc voltage, the converter must be able to produce a low-distortion high-power-factor ac current. The same aspects related with the voltage and current distortion produced by nonlinear loads can be considered for the injection of power into the grid. In the absence of a specific standard, this paper takes as a reference the limits for current harmonics given by international standards. The justification for this approach is that, from the resulting line voltage degradation, there is no difference between injected and absorbed currents. This paper presents a three-phase inverter using low-frequency commutation. An auxiliary circuit is added to the inverter topology to reduce the output voltage distortion, thus improving the current waveform. The main advantages of this approach are the minimization of the switching losses and the elimination of the electromagnetic interference, which avoids high-frequency filters necessary in high-frequency commutation inverters