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Description
The use of Photo Voltaic (PV) systems in battery charging applications has been on the rise for the past decade. A PV module generates direct current and relatively low voltage; this voltage needs to be increased and stabilized using a DC-DC converter before charging a battery load. Due to the intermittent nature of the PV system, the input voltage varies with respect to weather conditions; therefore, it is vital to control and adjust the output voltage. In this work, we first utilize a switch-mode DC-DC boost converter with a proposed feedback control for a solar battery charging system. A fixed frequency compensated voltage- mode controller is designed and implemented for a DC-DC boost converter operating in Continuous Conduction Mode (CCM). Secondly, we design a full-wave quasi resonant DC-DC boost converter, as a soft- switching technique, to increase the efficiency of DC- DC converter by reducing the switching losses is proposed. To achieve the soft switching functionality for the DC-DC boost converter, and to regulate a stable output voltage, a frequency control technique is proposed in this work. The proposed control strategy justifies both frequency and the duty cycle of the Pulse Width Modulated (PWM) control signal, which in turn controls the switching of the converter’s switches. Finally, an interleaved DC-DC quasi-resonant boost converter for PV based battery charging is proposed to increase the efficiency of the battery charger system by reducing the ripple across the battery load. The topology of the circuit implements a Maximum Power Point Tracking (MPPT) algorithm at a specified solar irradiation. The control technique proposes a solution to obtain maximum voltage using Perturb and Observation (PO) method, obtains a conversion ratio for the converter topology, and applies frequency modulation to regulate the output voltage in order to design a robust charger. Matlab Simscape toolbox is used to conduct the simulation studies evaluating the performance of the proposed circuit topologies and controllers for a PV-based battery charging system. Key Words— Soft Switching, Zero Current Switching (ZCS), Full-wave Quasi Resonant Converter, Interleaved Boost Converter (IBC), Photovoltaic (PV) System, Maximum Power Point Tracking (MPPT), Perturb and Observe (PO).
