Design of a single input triple output DC-DC converter for solar home system

Abstract

A new improved model of isolated three port converter (ITPC) is designed along with single input triple output (SITO) attribute for solar home system (SHS). The input side of the converter is connected to a PV panel as a single input source and a battery is connected to provide the standalone system of the proposed converter. Spotlight of the system is focused on multilevel output from single input. A highly efficient topology “identically switched storage and load (ISSL) with shifted pulse” is proposed considering the drawbacks of existing topologies of earlier converters. The proposed model will incorporate with a single control scheme based on pulse width modulation plus phase angle shift (PPAS) to provide overvoltage and low voltage protection for triple output levels. Control scheme contains maximum power point tracking (MPPT) loop and output voltage control loop. MPPT can be implemented by controlling duty cycle of the converter switches by using “incremental conductance and integral regulator technique”. In the output voltage control loop the phase angle of the modulation carrier is the control variable and PI controller is used to regulate the output voltage. According to IDCOL (Infrastructure Development Company Limited), a typical SHS operates at a rated voltage of 12V DC and provides power to small electrical appliances. In IDCOL standard, it is also specified that the rated input and output voltage should be maintained within the range of 12V, 24V or 48V and 110V-240V, respectively. In SHS installed in Bangladesh 125 V DC is used for longer distance transmission within the same house. The proposed system is simulated in MATLAB/SIMULINK platform. The proposed system shows the better performance than the earlier systems. Three distinct voltage levels 80V, 60V, 40V show better and stable output. The simulated efficiency of the proposed system is 98%. A practical circuit is implemented in laboratory and various data is extracted from the circuit. The simulation output is compared with practical data. The efficiency of the practical data is also high. The circuit can be used to optimize the performance of the SHS in Bangladesh.