A constant power (CP)-constant voltage (CV) protocol for battery charging is implemented in a conventional boost converter with output filter (BOF) by imposing loss-free resistor (LFR) behavior during the CP phase. To compare on equal basis the performance of the new CP-CV technique with the classical constant current (CC)–CV protocol, the latter is also implemented in the same power stage. The CC phase in BOF is attained by imposing a G-gyrator of type II behavior to the converter. A versatile controller uses the same voltage regulation loop for both protocols during the CV phase and a slightly different loop for the CP and CC phases. The latter loop is based in both CP and CC phases on the sliding-mode control (SMC) of the input inductor current of BOF, which in steady-state is made proportional to the input voltage in the LFR case or to the output voltage in the gyrator implementation. To compensate for the slow variations of the battery voltage during the CC phase, a proportional-integral (PI) current regulator has been added in the gyrator realization. The comparison of the corresponding experimental results shows identical behavior in both approaches in the measured waveforms, component stress, efficiency and external temperature. The simplicity of the CP-CV implementation based on LFR allows the extension of the proposed protocol to other hard-switching converters.

Modern DC-DC power conversion represents an important challenge because connected loads are not purely resistive as it has been conventionally considered. Furthermore, the corresponding power converters perform functions which are not limited to regulate either a specific output voltage or output current. One of these new functions is the transfer of a regulated power to different types of loads, which emerge in the context of microgrids and electric vehicles, in which the sliding-mode control (SMC) is an important actor because of its versality, robustness and systematic design. This paper presents SMC of a boost converter operating as a loss-free resistor (LFR), which supplies a constant power to the parallel connection of three canonical elements, namely, a constant power load (CPL), a constant current load (CCL) and a dc voltage source with internal resistance. The studied load is defined as a generic nonlinear static load (GNSL). The subsequent analysis of the connection of the controlled power converter and the GNSL reveals the existence of a single equilibrium point, which is unconditionally stable. This feature is preserved when the GNSL is particularized in the single load cases of battery, current source or resistor, and in all cases of two-element and three-element load combinations. The exception is the supply of a single CPL, which results in an infinite number of equilibrium points with marginally stable behavior. Simulation and measurements in a 1 kW prototype are in perfect agreement with the theoretical predictions.

The unstable ON and OFF state trajectories of a boost converter supplying a constant power load (CPL) are appropriately combined using sliding-mode control (SMC) with a suitable surface to yield a stable trajectory that reaches a specified equilibrium point. Selecting the optimum surface involves a comparative analysis among potential candidates in terms of stability, disturbance rejection, conduction losses and inrush current. The performance as switching function of polynomials of degree zero (non-zero constant), degree one (affine function) and degree 2 (quadratic function) are analyzed in depth to conclude that the affine function leads to the best static and dynamic results. The theoretical predictions are verified by means of simulations and measurements in a prototype.

Micro-size hydro power plants (μHPPs) are commonly used at remote areas to supply islanded AC micro-grids. A typical way to control grid frequency is to manipulate active power dissipated in ballast loads by AC/AC converters. However, these asymmetrically switched thyristor controlled converters consume reactive power degrading the power factor at the generator output. In this paper the operation of a symmetric angle switched, bridged three-phase rectifier and three single-phase rectifiers connected in series with ballast load, are studied to improve the power factor of the system. As a consequence, the objective is to evaluated the use of the three and single-phase rectifiers switched with symmetrical angle to improve the power factor, by reactive power compensation, at the output terminal of the electric generator of μHPPs that use ballast load to regulate frequency.

A computational thinking under simulated environment with amendable properties is promoted. It is exemplified on a real drum boiler multi-loop linear control. The model is based on the boiler-turbine plant P16/G16, which is oil-fired and the rated power is 160 MW, at the Sydvenska Kraft AB Plant in Malmö, Sweden. A proficient symbolic and numerical combination points out a fast and very efficient automatic engineering calculation. This contribution aims at tailor-made small simulators on Matlab for those industrial processes which are linked by heat energy. A first application at drum boiler with linear control meets a useful know-how to guide thoughts on how to translate physical fundamentals to Matlab codes for other industrial cases. Some comments relating to industrial practice are offered in this context.

Virtual laboratories are being used in automation design for integrator systems. Since the use of IEC 61131-3 languages is standardised in the industrial automation programming, the authors consider introducing these languages in the develop of virtual laboratories. The Virtual Laboratory of Automation at the University of Oriente (Cuba) works towards this goal. The SDAI teaching system include model analysis and design in Petri nets, programming and simulation control system in ladder diagrams and sequential functions chart languages. The functional requirements in real installation are verified. The integrate work of all parts is achieved for the use of IEC 1131 graphical languages facilities.

The perfection of sine wave power supply is always assumed, that is to say, voltage power supply has 50 or 60 Hz perfect sinusoidal waveform and its root mean square value is the rated one. It is known that electrical companies cannot supply this perfect kind of waveform, though in normal conditions they are within the limits imposed by regulations. Disturbances are generated under abnormal conditions such as lightning on a power system or the opening of a switch. These disturbances can affect electronic equipment. The equipment that requires a constant voltage is particularly affected. In this paper, the results of several tests accomplished are shown. The tests were carried out with linear power supplies, personal computers and programmable logic controllers (the last ones have switched power supplies) by means of the voltage sags generator designed by the Electrical Engineering Department of UPC. The latest technologies used in inverters of adjustable speed drives (IGBT for half power) have considerably increased bearing damage and dielectrics breakdown in induction motors due to use conditions of these converters. This fact has contributed to increasing the research to establish solid theories which explain these phenomena and help to find solutions for them. Problems related to voltage feeder disturbances also remain unsolved. This aspect is becoming more and more important for the users, since it is the main cause of interruption in multiple industrial processes. The aim of this study is to establish theoretical and experimental bases that help to understand and solve those problems arising in industrial applications, and also to provide users with useful tools for the correct operation and maintenance of the installation.

An embedded network linked by CAN (controller area network) controllers and the CEINFO software tool are combined. It solves the university's teaching about the industrial automation. To generate codes for the distributed control units (DCU), to develop an operating system for the intelligent gateway handling them, to control the monitored process. The ALDS software, version 1.0 guarantees the cooperative work in real time over the CAN network. The embedded network consists of "Evaluation CAN-ISA gateway card based in the MCS51" and several modules developed with the PIC16F877 Process Microcontroller and the MCP2510 CAN controller. The paper explains a simplified variant to built the communication objects (derived of the CANopen model) PDO, SDO and NMT using a little bit of hardware resources.