Carlos A. Villarreal-Hernandez

This paper presents a current-based control for a proton-exchange membrane fuel cell using the so-called double dual boost topology. In particular, we introduce a discrete time controller that, in coordination with a particular selection of inductors and capacitors, minimizes the switching ripple at the input port (current ripple) and the output port (voltage ripple) of the double dual boost converter. This converter has a particular characteristic, in contrast to the classical interleaved boost topology, in the double dual boost, the phases of the converter can have different duty ratios. The freedom to choose the duty ration for each phase can be used to select the operative point in which the input current is equal to zero. However, if individual controllers are used for each branch of the converter, the equilibrium after a transient can differ from the minimum ripple operation point; the proposed scheme regulates the output voltage and, at the same time, ensures the equilibrium remains in the minimum ripple operation in steady state. In this way, the converter can mitigate the harmonic distortion on the current extracted from the proton-exchange membrane fuel cell, which is beneficial to improve the efficiency and lifetime of the cell, and on the output voltage delivered to an output direct current bus. The results of the experiment are presented to validate the principles of the proposed system.

This work presents a power-electronics based system for renewable energy applications, the system is driven with an only one switch quadratic type boost converter, the discussed converter is based on a stack of switching stages which provide a large voltage gain, a desirable feature for fuel cell generation systems, the converters gain function is the quadratic boost-type converters; furthermore, the topology can be extended. The major benefit of the topology is that there is not a capacitor that sustains the entire output voltage, in contrast to other similar topologies in which there is a capacitor rated to the output port voltage, there is no high voltage capacitor in this system. Experimental verification is presented to confirm the system principles; experiments included a fuel cell emulator that was built and used for the experiments.

This paper introduces a control design framework for modern DC-DC topologies with high-order dynamics. In particular, model-based and model-free approaches using high-order controllers are introduced. The model-based approach permits the use of a minimum number of sensors, even for converters with a high-number of components (e.g. multilevel, quadratic, input/output LC filter-based converters, etc.). This setting does not require estimation of state variables and its gain tuning can be achieved by selecting time-response specifications. The proposed model-free approach control exhibits the same, as well as some additional characteristics. Namely, controllers can be synthesized without the requirement of an explicit dynamic model; and gain tuning with guaranteed stability is directly achieved from measurement data. The latter controller is implemented in discrete-time, which facilitates a digital implementation. The proposed approaches are validated through the control design and closed-loop implementation of a sixth-order topology.

This paper introduces discrete-time controllers for double dual boost converters, suitable for renewable energy applications. The proposed schemes are based on a current ripple mitigation technique, which enables an unconstrained input-to-output voltage converter gain. This is in contrast with classical interleaved topology implementations, where duty cycles are restricted (e.g. to 50%). A discrete-time small-signal controller is proposed for those applications that require nominal specifications. This control strategy is based on a novel linear difference system approach, while gain tuning is performed via numerical computation of LMIs (linear matrix inequalities). In addition, a discrete-time large-signal controller is proposed for those applications that require trajectory tracking. The proposed controllers, their stability, performance and ripple cancellation properties, are theoretically validated via experimental results.

This article presents a novel output current/voltage control for interleaved dc-dc converters with dual switched input inductors, i.e., interleaved input inductors controlled by independent switches. The proposed approach is able to guarantee a minimum input current ripple point tracking despite of variations on the operating point. The controller encompasses three control stages: current stabilization, output-voltage regulation, and minimum input current ripple control. In contrast with the two first loops, the latter is a novel stage introduced in this article to allow operation with minimum input current ripple in the whole operating region. That is, even though the converter has been designed for operation with minimum ripple in a given operating point, the scheme is able to dynamically deviate from this point to a new one where the ripple is minimized and the output voltage remains constant. The proposed scheme is experimentally validated using a laboratory prototype of a high-gain interleaved multilevel boost converter.