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Bidirectional power flow is needed in many power conversion systems like energy storage systems, regeneration systems, power converters for improvement of the power quality and some DC-DC applications where bidirectional high power conversion and galvanic isolation are required. The dual active bridge (DAB) is an isolated, high voltage ratio DC-DC converter suitable for high power density and high power applications, being a key interface between renewable energy sources and energy storage devices. This paper is focused on the modeling and control design of a DC-DC system with battery storage based on a DAB converter with average current mode control of the output current and output voltage control. The dynamic response of the output voltage to load steps is improved by means of an additional load-current feed-forward control loop. An analytical study of the load-current feed-forward is presented and validated by means of both simulations and experimental results.

In testing maximum power point tracking (MPPT) algorithms running on electronic power converters for photovoltaic (PV) applications, either a PV energy source (PV module or PV array) or a PV emulator is required. With a PV emulator, it is possible to control the testing conditions with accuracy so that it is the preferred option. The PV source is modeled as a current source; thus, the emulator has to work as a current source dependent on its output voltage. The proposed emulator is a buck converter with an average current mode control loop, which allows testing the static and dynamic performance of PV facilities up to 3 kW. To validate the concept, the emulator is used to evaluate the MPPT algorithm of a 230-W experimental microinverter working from a single PV module.

In photovoltaic (PV) double-stage grid-connected inverters a high-frequency DC-DC isolation and voltage step-up stage is commonly used between the panel and the grid-connected inverter. This paper is focused on the modeling and control design of DC-DC converters with Peak Current mode Control (PCC) and an external control loop of the PV panel voltage, which works following a voltage reference provided by a maximum power point tracking (MPPT) algorithm. In the proposed overall control structure the output voltage of the DC-DC converter is regulated by the grid-connected inverter. Therefore, the inverter may be considered as a constant voltage load for the development of the small-signal model of the DC-DC converter, whereas the PV panel is considered as a negative resistance. The sensitivity of the control loops to variations of the power extracted from the PV panel and of its voltage is studied. The theoretical analysis is corroborated by frequency response measurements on a 230 W experimental inverter working from a single PV panel. The inverter is based on a Flyback DC-DC converter operating in discontinuous conduction mode (DCM) followed by a PWM full-bridge single-phase inverter. The time response of the whole system (DC-DC + inverter) is also shown to validate the concept. Copyright © 2011 John Wiley & Sons, Ltd. In photovoltaic (PV) double-stage gridconnected inverters a high-frequency DC-DC isolation and voltage step-up stage is commonly used between the panel and the grid-connected inverter. This paper is focused on the modeling and control design of DC-DC converters with Peak Current mode Control (PCC) and an external control loop of the PV panel voltage, which works following a voltage reference provided by a maximum power point tracking (MPPT) algorithm. The sensitivity of the control loops to variations of the power extracted from the PV panel and of its voltage is studied. Copyright © 2011 John Wiley & Sons, Ltd. Copyright © 2011 John Wiley & Sons, Ltd.