Abstract:

This paper presents the design and development of a novel highly efficient synchronous buck converter operating both as a battery charge controller with five stage charging method and also as improved Maximum Power Point Tracker (MPPT) for operation in Solar Photovoltaic (PV) Systems. The algorithm regulates the duty cycle of the switching devices of the converter following a variable step size perturb and observe (P&O) MPPT technique. At the same time it provides precise control on the battery charging voltage and current according to five charging stages which is desirable for protection of battery health and maximizing charging rate. Thus the algorithm developed provides a combined solution for maximizing the transfer of solar electricity generated by the PV module(s) and also ensuring a long battery lifetime. Both these aspects, which are generally investigated separately earlier, are treated in an integrated fashion in this work. The work analyses in detail about the converter power loss as well as describes the development of MPPT technique and battery charging method used in the controller. A prototype of 1500W MPPT Charge Controller based on this algorithm has been designed, fabricated and tested. It shows satisfactory performance of the MPPT charge controller in terms of performance parameters i.e. converter efficiency, MPP tracking efficiency, MPP tracking time, fluctuation of PV operating point around MPP, input operating voltage range of the controller, independency of battery type as well as provision of temperature compensation.

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