Toward the Design of Control Algorithms for a Photovoltaic Equalizer: Choosing the Optimal Switching Strategy and the Duty Cycle

The photovoltaic equalizer is a promising response to the problems of partial shading in photovoltaic modules. Equipped with a network of transistors, this system can connect itself to the unshaded cells of the photovoltaic module, gather their excess current, and share it with the shaded cells. Thus, for a given shadow, the equalizer must always choose the transistors to activate and their associated duty cycle. This paper studies the impacts of these choices over power production in two parts. First, a quasi-exhaustive simulation is used to find the best transistors to activate for maximizing power production under a given shadow. Second, changes in the duty cycle are applied and its effects evaluated by analyzing the I-V curve of the associated PV module. All simulations are validated through measurements. The conclusions are summarized into behavior laws which can be used to develop algorithms for the equalizer control system.