Ignacio Lizama

Bio: Ignacio Lizama is an academic researcher from Valparaiso University. The author has contributed to research in topics: AC power & Model predictive control. The author has an hindex of 7, co-authored 9 publications receiving 1527 citations.

A Survey on Neutral-Point-Clamped Inverters

Abstract: Neutral-point-clamped (NPC) inverters are the most widely used topology of multilevel inverters in high-power applications (several megawatts). This paper presents in a very simple way the basic operation and the most used modulation and control techniques developed to date. Special attention is paid to the loss distribution in semiconductors, and an active NPC inverter is presented to overcome this problem. This paper discusses the main fields of application and presents some technological problems such as capacitor balance and losses.

A Predictive Control Scheme for Current-Source Rectifiers

Abstract: Current-source rectifiers (CSRs) constitute a commonly used topology in high-power applications, featuring several advantages such as regeneration capability and high-quality currents. This paper presents a simple predictive control scheme for a CSR. The main achievements of the control scheme presented here are the simplicity in controlling the dc-link current and the generation of currents with unity displacement power factor. Experimental results are presented to validate the proposed control principle.

Predictive control of the Indirect Matrix Converter with active damping

Abstract: A predictive control scheme for the Indirect Matrix Converter including a method to mitigate the resonance effect of the input filter is presented. A discrete-time model of the converter, the input filter and the load is used to predict the behavior of the reactive power and the output currents for each valid switching state. The control scheme selects the state that minimize the value of a cost function in order to generate input currents with unity power factor and output currents with a low error respect to a reference. Additionally, the predictive controller is enhanced by including active damping scheme in order to mitigate the effects of the resonance of the input filter. Results in simulation and spectral analysis confirm the good performance of the strategy, allowing controlling the converter in a simple and intuitive manner.

Method and apparatus for short circuit protection of power semiconductor switch

Abstract: The present disclosure presents a method, and an apparatus implementing the method, for a power semiconductor switch, wherein a current through the switch is responsive to a control terminal voltage at a control terminal of the switch, and the control terminal voltage is driven by a driver unit, The method comprises estimating the current on the basis of a bond voltage of the switch, detecting a short circuit by comparing the estimated current to a short circuit current limit, controlling an on-state voltage level of the control terminal voltage on the basis of the comparison in order to limit the current through the switch during the short circuit, and controlling the control terminal voltage to an off-state voltage level in order to turn the switch off. The on-state voltage level voltage is controlled by pulse-width modulating the output of the driver unit. A switching frequency of the modulation is at least the cut-off frequency of low-pass characteristics of the control terminal.

Predictive control for current source rectifiers operating at low switching frequency

Abstract: Current source converters are the state of art in high power applications featuring several advantages such the simplicity in the topology, the regeneration capability and the capacity to produce sinusoidal input currents. This converter features a very weak damped LC filter in the input, whose resonance frequency can be excited by the control and harmonics of the mains. In this work a new predictive control scheme is presented, which operates the rectifier at very low switching frequency and can generate sinusoidal currents with unity power factor and low distortion. Simulation results are presented in order to validate the proposed scheme.

State of the Art of Finite Control Set Model Predictive Control in Power Electronics

Abstract: This paper addresses to some of the latest contributions on the application of Finite Control Set Model Predictive Control (FCS-MPC) in Power Electronics. In FCS-MPC , the switching states are directly applied to the power converter, without the need of an additional modulation stage. The paper shows how the use of FCS-MPC provides a simple and efficient computational realization for different control objectives in Power Electronics. Some applications of this technology in drives, active filters, power conditioning, distributed generation and renewable energy are covered. Finally, attention is paid to the discussion of new trends in this technology and to the identification of open questions and future research topics.

Model Predictive Control for Power Converters and Drives: Advances and Trends

Abstract: Model predictive control (MPC) is a very attractive solution for controlling power electronic converters. The aim of this paper is to present and discuss the latest developments in MPC for power converters and drives, describing the current state of this control strategy and analyzing the new trends and challenges it presents when applied to power electronic systems. The paper revisits the operating principle of MPC and identifies three key elements in the MPC strategies, namely the prediction model, the cost function, and the optimization algorithm. This paper summarizes the most recent research concerning these elements, providing details about the different solutions proposed by the academic and industrial communities.

Power Electronics Converters for Wind Turbine Systems

Abstract: The steady growth of installed wind power together with the upscaling of the single wind turbine power capability has pushed the research and development of power converters toward full-scale power conversion, lowered cost pr kW, increased power density, and also the need for higher reliability. In this paper, power converter technologies are reviewed with focus on existing ones and on those that have potential for higher power but which have not been yet adopted due to the important risk associated with the high-power industry. The power converters are classified into single- and multicell topologies, in the latter case with attention to series connection and parallel connection either electrical or magnetic ones (multiphase/windings machines/transformers). It is concluded that as the power level increases in wind turbines, medium-voltage power converters will be a dominant power converter configuration, but continuously cost and reliability are important issues to be addressed.

Future on Power Electronics for Wind Turbine Systems

Abstract: Wind power is still the most promising renewable energy in the year of 2013. The wind turbine system (WTS) started with a few tens of kilowatt power in the 1980s. Now, multimegawatt wind turbines are widely installed even up to 6-8 MW. There is a widespread use of wind turbines in the distribution networks and more and more wind power stations, acting as power plants, are connected directly to the transmission networks. As the grid penetration and power level of the wind turbines increase steadily, the wind power starts to have significant impacts to the power grid system. Therefore, more advanced generators, power electronic systems, and control solutions have to be introduced to improve the characteristics of the wind power plant and make it more suitable to be integrated into the power grid. Meanwhile, there are also some emerging technology challenges, which need to be further clarified and investigated. This paper gives an overview and discusses some development trends in the technologies used for wind power systems. First, the developments of technology and market are generally discussed. Next, several state-of-the-art wind turbine concepts, as well as the corresponding power electronic converters and control structures, are reviewed, respectively. Furthermore, grid requirements and the technology challenges for the future WTS are also addressed.

High-Power Wind Energy Conversion Systems: State-of-the-Art and Emerging Technologies

Abstract: This paper presents a comprehensive study on the state-of-the-art and emerging wind energy technologies from the electrical engineering perspective. In an attempt to decrease cost of energy, increase the wind energy conversion efficiency, reliability, power density, and comply with the stringent grid codes, the electric generators and power electronic converters have emerged in a rigorous manner. From the market based survey, the most successful generator-converter configurations are addressed along with few promising topologies available in the literature. The back-to-back connected converters, passive generator-side converters, converters for multiphase generators, and converters without intermediate dc-link are investigated for high-power wind energy conversion systems (WECS), and presented in low and medium voltage category. The onshore and offshore wind farm configurations are analyzed with respect to the series/parallel connection of wind turbine ac/dc output terminals, and high voltage ac/dc transmission. The fault-ride through compliance methods used in the induction and synchronous generator based WECS are also discussed. The past, present and future trends in megawatt WECS are reviewed in terms of mechanical and electrical technologies, integration to power systems, and control theory. The important survey results, and technical merits and demerits of various WECS electrical systems are summarized by tables. The list of current and future wind turbines are also provided along with technical details.