Performance of a Bipolar Output Voltage DC-DC Converter for Voltage Regulation for Solar PV System Application

A combined Single-Ended Primary-Inductor Converter (SEPIC) and Cuk DC-DC converter that provides a bipolar outputs voltage at the DC bus is widely used in applications especially solar photovoltaic (SPV) system. Maintaining constant output voltages at the DC bus under variable loads and input voltage from SPV is of great interest to many researchers. This paper presents a 400 W mathematical model of a combined SEPIC and Cuk DC-DC converter through state space averaging (SSA) in a continuous conduction mode (CCM). A nested voltage and current control loops are used to regulate voltage and increase the performance of the converter. These controls use Proportional-Integral (PI) controllers to track the desired input reference signal and eliminate any disturbance from the load. The entire model with its control algorithm was modelled in MATLAB/Simulink environment and validation results to evaluate its performance are presented. The controller was able to maintain required bus voltage of 24 V DC and -/+12 V at the output DC bus. DC bus voltage regulation was tested at varying input voltages and varying loads connected at the output, where, in all those scenarios, the converter could regulate its output voltage to required value.