B. Estibals

An adaptive control developed for Multi-Phase Converters based on look-up tables and applied to photovoltaic conversion systems

This paper presents an Adaptive Multi-Phase Converter (AMPC) used as a perfect matching stage to improve the global energy production and conversion efficiency of a photovoltaic power conversion system. A control law was specially developed to guarantee high conversion efficiency, even in presence of a constantly changing operating point, which is the main constraint in a traditional photovoltaic system design. Another control law was designed to reduce the stress on the components of each converters phase and then to insure a higher life time for the system. Through this control, we proposed a rotation algorithm that guarantees an homogeneous aging of the phases and increases the average lifetime of the converter. Examples of guidelines of these control laws are presented with their impact on the efficiency. An experimental prototype has been designed to evaluate the performances of this proposed adaptation stage and to validate this concept in real field operating conditions.

Analysis and design of digital predictive current-mode control techniques for high-frequency VRMs

Digital predictive techniques are nowadays an attractive option for current-mode controlled voltage regulator modules. This article examines the implementation of two digital predictive control laws and their application in a typical case for this kind of loads. The simulation results presented in this paper illustrate the pros and contras of both techniques.

Comparative study of the optimal number of phases for interleaved Voltage regulator modules

This paper studies several solutions to choose the most appropriated number of phases for a high- current low-voltage interleaved voltage regulator module (VRM). Several criteria have been considered as transient responses, harmonic contents (EMI levels) or converter efficiency to find the optimal topology of the converter. A theoretical comparison between classical single-phase converters with those multi-phased has been established. Finally, we have extracted some results to determine the optimal number of phases.

FPGA-based digital voltage-current controller for a buck converter

This paper introduces an analysis and design of a digital controlled double loop voltage-current for a buck converter. Taking into account the implementation requirements, the chosen platform was an Field-Programmable Gate Array (FPGA). This paper also shows in detail the analog-digital interface. The study is completed by a detailed analysis of the FPGA programming including states machines and logic diagrams. Finally, theoretical results are validated with extensive simulations.

Rotational adaptative-multilevel converter control strategy based on FPGA

In this paper, a control method for autonomous changing the number of parallel driven DC-DC converter is proposed. In order to improve efficiency of the parallel driving, the number of parallel driven converters is dynamically changed for the variations of output power. Taking into account the implementation requirements, the chosen platform was an Field-Programmable Gate Array (FPGA). This paper also shows in detail the analog-digital interface. The study is completed by a detailed analysis of the FPGA programming including states machines and logic diagrams. Finally, an experimental comparison with a typical single converter topology is done.

Input current characterization for interleaved multiphase Voltage Regulator Modules

The presented work studies various effects in the input-current waveform in switched Voltage Regulator converters. As a first step, the input current has been mathematically characterized. This description is called up to find the relationship among the number of phases of the power converter, its duty cycle and its harmonic content. The following conclusion associated to the last model, is the optimal design for the input capacitor. The mathematical formulation depicted in this paper is validated by means of simulation results.

Analysis and design of Power R Gyrators for Voltage Regulation

This paper presents a new type of voltage regulators based on the power R-gyrators concept. Also, the semigyrator notion is introduced. Power R-semigyrators based in boost and boost-shunt converter are presented. Finally, voltage regulation is achieved with both types of semigyrators

FPGA-based improvement of classical current tracking methods for high-frequency power converters

Embedded microprocessors require efficient supply management systems to optimize its power consumption and to enhance their calculation potentials. Typically, the modules performing this function are known as Voltage Regulator Modules (VRMs). It is widely adapted that current-programmed regulation techniques own leveraging skills in the control of this kind of power converters. However, these strategies require a fine inductor-current sensing to achieve accurate results. One critical issue in the inductor-current sensing is the effect of parasitic inductances in the measurement loop. This undesirable effect produces a considerable mismatch between the real inductor-current waveform and the equivalent voltage image captured thanks to the shunt resistance. Further, this unwanted deviation augments as long as the current value is increased. As a result, this problem makes loosely the data obtained. However, todays commercial digital controllers, like FPGAs1, can be used to reduce overwhelmingly the aforementioned drawback. The presented work exploits some intrinsic advantages of FPGAs such as its great processing speed and its parallel working mode to overcome this drawback. Therefore, a new digital auto-tuning system is proposed in which this undesirable effect is treated and compensated. The obtained result is a digital signal which avoids the parasitic effect of the inductance in the measurement loop. In the last part of our work, some experimental results, using a FPGA, validate the advantages of the proposed method.