Debugging digital controllers for power converters can be a problem because there are both digital and analog components. This paper focuses on debugging digital controllers to be implemented in Field Programmable Gate Arrays or Application Specific Integrated Circuits, which are designed in hardware description languages. Four methods are proposed and described. All of them allow simulation, and two methods also allow emulation-synthesizing the model of the converter to run the complete closed-loop system in actual hardware. The first method consists in using a mixed analog and digital simulator. This is the easiest alternative for the designer, but simulation time can be a problem, specially for long simulations like those necessary in power factor correction or when the controller is very complex, for example, with embedded processors. The alternative is to use pure digital models, generating a digital model of the power converter. Three methods are proposed: real type, float type and fixed point models (in the latter case including hand-coded and automatic-coded descriptions). Float and fixed point models are synthesizable, so emulation is possible, achieving speedups over 20 000. The results obtained with each method are presented, highlighting the advantages and disadvantages of each one. Apart from that, an analysis of the necessary resolution in the variables is presented, being the main conclusion that 32-bit floating point is not enough for medium and high switching frequencies.

This is the author’s version of a work that was accepted for publication in Measurement. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Measurement, Vol. 45, Issue 3, (2012) DOI: http://dx.doi.org/10.1016/j.measurement.2011.12.002This work presents a low cost 3-D location system based on ultrasonics and implemented with low-cost FPGAs. The mobile nodes of the system use distance estimation to several anchor points in order to trilaterate their positions with an accuracy of few centimeters. The ultrasonic transducers are handled with an ad hoc conditioning circuit based on instrumental amplifiers which provides high amplification keeping low noise. The proposed system is autonomous so there is no need of an external PC or other devices. A prototype of the system has been attached to a mobile robot to check the viability of the location system in a real scenario.This work has been partially supported by the TEC2009-09871 project of the Ministerio de Ciencia e Innovacion, Spain

Traditional digital power factor correction (PFC) uses three sensors to measure the input and output voltages and the input current. Each sensor, especially the input current one, increases the cost of the system and generates power losses in case of resistive sensors. This paper presents a controller for boost PFC converters. It uses precalculated duty cycles generated offline, and applies them to the switch. In order to control the converter with nonnominal conditions, just one analog-to-digital converter (ADC) is used, which measures the output voltage. Measuring the average and the ripple of the output voltage with this ADC, the controller takes compensation action for changes in the input voltage but also in the load of the converter. The average value is used to control the input voltage changes, while the ripple value is used to control load changes. These two loops present low frequency bandwidth, so the ADC and the whole system can be low cost. Finally, a comparator is used to detect the zero-crossing of the input voltage, so the precalculated values are synchronized with the ac mains. In this way, the converter only uses one ADC and one comparator, both with low bandwidth. Results show that high power factor and normative compliance are reached, even under nonnominal conditions.

This paper presents a mapping system that is suitable for small mobile robots. An ad hoc algorithm for mapping based on the Occupancy Grid method has been developed. The algorithm includes some simplifications in order to be used with low-cost hardware resources. The proposed mapping system has been built in order to be completely autonomous and unassisted. The proposal has been tested with a mobile robot that uses infrared sensors to measure distances to obstacles and uses an ultrasonic beacon system for localization, besides wheel encoders. Finally, experimental results are presented.

Silicon dioxide has been deposited from electron cyclotron resonance silane/oxygen plasmas at temperatures below 150 °C. Deposition rates over 4000 Å/min have been obtained. The refractive indexes in the measuring range of 1.5–4.5 eV were found to be almost insensitive to the different deposition rates and flux ratio regimes except in the near infrared region where small deviations from thermal oxide indexes were observed. Etch rates and refractive indexes were very close to the thermal oxide values for low silane/oxygen flow ratios 0.025, whereas the refractive index decreased and the etch rate increased for the largest flow ratios used (0.20). After a low temperature annealing, 500 °C in nitrogen ambient, the refractive indexes reached the best obtained values and were independent of the conditions under which the layers were deposited.

Photoluminescence and Hall-effect measurements on neutron transmutation doped liquid-phase-epitaxial GaAs layers were performed. The obtained results clearly point out that at least a part of the Ge atoms introduced by transmutation of Ga leave their original lattice site behaving as acceptors. The probable cause of these displacements are the recoils during γ and β emissions from the unstable Ga isotopes.