Fast and efficient solar incremental conductance MPPT using lock-in amplifier

摘要

Peak energy harvesting in Photovoltaic (PV) systems requires fast and effective Maximum Power Point Tracking (MPPT) detection. Incremental Conductance (InCond) MPPT is one of the most popular detection methods, given its simple implementation and accuracy. In this paper, a new InCond technique is proposed based on small-signal identification and adaptive-step using a Lock-In Amplifier (LIA). The use of small-signal identification virtually eliminates the losses typically encountered in traditional large-signal MPPT perturbations. This feature improves the steady-state efficiency, while the LIA allows for robust and accurate measurement of the equivalent AC resistance to achieve maximum power extraction, even in the presence of noise. The proposed algorithm enables fast tracking during both static and changing environmental conditions, as well as smooth operation in steady-state. The proposed implementation reduces the adaptive-step InCond to a simple Discrete-Time Integral Controller, simplifying its analysis and configuration. Overall, the proposed implementation delivers superior results with similar hardware both during transients and in steady state. Simulations and experimental results are provided to validate the proposed implementation, and to illustrate its behavior in steady and transient operations.