This paper deals with the optimization of maximum power point tracking when a photovoltaic panel is modelled as two diodes. The adopted control is implemented using a sliding mode control (SMC) and the optimization is implemented using an improved Pattern Search Method. Thus, the problem of maximum power point tracking is reduced to an optimization problem whose solution is implemented by Pattern Search Techniques, inheriting their convergence properties. Simulation examples show the effectiveness of the proposed technique in practice, being able to deal with different radiations. In addition, improved pattern search method (IPSM) is compared with other techniques such as perturb & observe and Particle Swarm optimization, after which IPSM presents lower energy losses in comparison with the other two algorithms, with the advantage of ensuring the location of the optimal power point in all cases.

Stand-alone power systems based on renewable energy sources are used to replace generators based on fossil fuels. Those renewable power systems also require Energy Storage Devices (ESD) interfaced by a charger/discharger power converter, which consist of a bidirectional DC/DC converter, and a DC bus. This paper proposes a single sliding-mode controller (SMC) for the charger/discharger DC/DC converter to provide a stable DC bus voltage in any operation condition: charging or discharging the ESD, or even without any power exchange between the ESD and the DC bus. Due to the non-linear nature of the power converter, the SMC parameters are adapted on-line to ensure global stability in any operation condition. Such stability of the adaptive SMC is mathematically demonstrated using analytical expressions for the transversality, reachability and equivalent control conditions. Moreover, a design procedure for the adaptive SMC parameters is provided in order to ensure the dynamic response required for the correct operation of the load. Finally, simulations and experimental tests validate the proposed controller and design procedure.

A novel asymmetrical interleaved dc/dc switching converters family intended for photovoltaic and fuel cell applications is presented in this paper. The main requirements on such applications are small ripples in the generator and load, as well as high voltage conversion ratio. Therefore, interleaved structures and voltage multiplier cells have been asymmetrically combined to generate new converters, which inherently operate indiscontinuous conduction mode. The novel family is derived from boost, buck-boost and flyback-based structures. This converter family is analyzed to obtain the design equations and synthesize a design process based on the typical requirements of photovoltaic and fuel cell applications. Finally, the experimental results validate the characteristics and usefulness of the asymmetrical interleaved converter family.

Stand-alone power systems based on renewable energy sources are widely used for energy generation in remote locations and for distributed generation in urban environments. The DC bus is an essential component of these systems since it enables power transmission between the sources, loads and batteries. The batteries are interfaced with the bus using a charger/discharger DC/DC converter, which is controlled to regulate the DC bus voltage under any operating conditions. This is an important task because unsafe over-voltages and under-voltages in the bus could damage the sources, loads and power converters. This paper proposes a sliding-mode controller for a charger/discharger DC/DC converter with improved disturbance rejection to provide a tight bus voltage regulation for safe operation. The main novelty of this solution is the inclusion of the bus current in the sliding surface, which accelerates the controller response. Moreover, a formal proof of the system global stability is provided, and a detailed process is developed to calculate the controller and implementation parameters. Finally, the proposed solution is validated through simulations and experiments.

Regulation of DC‐bus voltages is important for the stable operation of different applications, like microgrids and electric vehicles, and it is usually performed by charging/discharging (C/D) batteries. Such C/D system is formed by a power converter and a control system, and it is aimed at guaranteeing the system stability and extending the battery life. To extend the battery life, it is important to reduce the battery current ripples, which is usually performed with interleaved converters and nonlinear controllers; however, most of those controllers do not provide the design procedure nor guarantee the system stability. This paper proposes a nonlinear control strategy to regulate the voltage in a DC‐bus by C/D a battery through a two‐branch interleaved Boost converter. The proposed control strategy is formed by two sliding mode controllers (SMCs), where the first one regulates the DC‐bus voltage by acting on the first converter branch and the second SMC controls the current in the second branch. The reference of the second SMC is generated from the delayed current of the first branch, in order to coordinate the controllers and to reduce the ripples in the battery current. The paper includes a procedure to design the two SMCs as well as simulation and experimental results to validate the proposed solution and to illustrate its performance. The results prove the system stability and its dynamic performance according to the design.

A recent approach to mitigate the adverse effects of photovoltaic (PV) arrays operating under mismatching conditions is the dynamic electrical reconfiguration of the PV panels. This paper introduces a procedure to determine the best configuration of a PV array connected in a series-parallel structure without using complex mathematical models. Such a procedure uses the experimental current vs. voltage curves of the PV panels, which are composed of multiple PV modules, to construct the power vs. voltage curves of all of the possible configurations to identify the optimal one. The main advantage of this method is the low computational effort required to reconstruct the power vs. voltage curves of the array. This characteristic enables one to implement the proposed solution using inexpensive embedded devices, which are widely adopted in industrial applications. The proposed method, and its embedded implementation, were tested using a hardware-in-the-loop simulation of the PV system. Finally, the real-time operation and benefits of the proposed solution are illustrated using a practical example based on commercial devices.