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ABSTRACT. This paper presents the modified perturb and observe (P&O) maximum power point tracking (MPPT) method for photovoltaic (PV) fed three-port DC-DC converter in PV/battery hybrid system. The proposed MPPT technique reduces the drift problem which occurs in the conventional MPPT methods by including the data of change in current (ΔI) in addition to the data used in the conventional P&O algorithm. The drift phenomenon and its effects are clearly demonstrated in this paper. The ability of the proposed P&O method to address this issue is proved by comparing the conventional P&O algorithm in different modes of operation. The performance assessment includes peak overshoot, settling time, MPP ratio and stability. The experimental validation was implemented using DSPIC30F4011 microcontroller. From the analysis and results, it could be seen that the modified P&O showed better performance in terms of accuracy in tracking the maximum power, less tracking time, high MPP ratio and reduced drift in the changing weather conditions. Keywords: current-voltage characteristics, DC-DC power converters, drift, photovoltaic systems, power demand, pulse width modulation.Impacto da modificação perturbar e observar de controle na MPPT de PV / bateria fed Três -port conversor DC-DC RESUMO. Este artigo apresenta o método de monitoramento de ponto de potência máximo (MPPT) modificado e observado (P&O) para o conversor DC-DC de três portas alimentado por energia fotovoltáica (PV) no sistema híbrido PV/bateria. A técnica MPPT proposta reduz o problema de deslocamento (drift) que ocorre nos métodos MPPT convencionais, incluindo os dados de mudança na corrente (ΔI), além dos dados usados no algoritmo P&O convencional. O fenômeno do deslocamento (drift) e seus efeitos estão claramente demonstrados neste artigo. A capacidade do método de P&O proposto para resolver este problema é comprovado comparando com o algoritmo de P&O convencional em diferentes modos de operação. A avaliação de desempenho inclui o superávit do pico, tempo de estabilização, relação de MPP e estabilidade. A validação experimental foi implementada usando o microcontrolador DSPIC3o30F4011. A partir da análise e dos resultados, verificou-se que o P&O modificado mostrou melhor desempenho em termos de precisão no rastreamento da potência máxima, menor tempo de rastreamento, alta relação de MPP e deslocamento reduzido nas condições climáticas em constante mudança.Palavras-chave: características corrente-tensão, conversores de potência DC-DC, deslocamento, sistemas fotovoltáicos, demanda de energia, modulação de largura de pulso.

This paper presents a derived SEPIC/ZETA bidirectional converter (BDC) with reduced ripple in the noninverted output voltage. This converter is obtained by the fusion of unidirectional SEPIC and ZETA converters that ensures reduced ripple in the inductor currents. The optimal selection of duty ratio enables the proposed converter to operate either in SEPIC or ZETA mode under forward and reverse power flow. The presence of auxiliary circuit not only reduces the voltage stress on the switches by operating under zero voltage switching condition but also provides isolation between the input and the output ports. The operational principle and the stability of the proposed SEPIC/ZETA BDC have been analyzed under different modes of operation. To validate the performance of the proposed converter, the implementation is carried out using a field programmable gate array (FPGA)-based digital controlled prototype model.

Multiport DC-DC converters have been most commonly used in stand-alone renewable power systems to provide smooth and constant power to the loads. To supply the load without any interruption under various disturbances, the centralised controller in various typologies of multiport converter has been implemented only by using conventional proportional integral (PI) controller. This study presents the output voltage control of the three-port full-bridge converter interfacing photovoltaic (PV) system with three different controllers. The dynamic response of the proposed converter is analysed with the PI controller, fuzzy logic controller (FLC), and the sliding mode controller (SMC). The state space model of the three-port full-bridge converter is developed to analyse the performance using SMC. PI, FLC, and SMC-based control scheme is developed using the MATLAB/Simulink environment. The response of the PI, FLC, and SMC are analysed for line regulation, load voltage regulation, and for the converter parameter variation. The simulation results illustrate that the SMC gives a better steady state and dynamic response when compared with the PI and FLC. The results are presented to confirm the proposed control schemes.Keywords: power converter; fuzzy control; PI control; renewable energy sources; sliding mode control; state-space methods.Reference to this paper should be made as follows: Mahendran, V. and Ramabadran, R. (2017) 'Analysis of controllers for the dynamic response enhancement of the three-port full-bridge DC-DC converter interfacing photovoltaic system', Int.

Multiport DC-DC converters have been most commonly used in stand-alone renewable power systems to provide smooth and constant power to the loads. To supply the load without any interruption under various disturbances, the centralised controller in various typologies of multiport converter has been implemented only by using conventional proportional integral (PI) controller. This study presents the output voltage control of the three-port full-bridge converter interfacing photovoltaic (PV) system with three different controllers. The dynamic response of the proposed converter is analysed with the PI controller, fuzzy logic controller (FLC), and the sliding mode controller (SMC). The state space model of the three-port full-bridge converter is developed to analyse the performance using SMC. PI, FLC, and SMC-based control scheme is developed using the MATLAB/Simulink environment. The response of the PI, FLC, and SMC are analysed for line regulation, load voltage regulation, and for the converter parameter variation. The simulation results illustrate that the SMC gives a better steady state and dynamic response when compared with the PI and FLC. The results are presented to confirm the proposed control schemes.Keywords: power converter; fuzzy control; PI control; renewable energy sources; sliding mode control; state-space methods.Reference to this paper should be made as follows: Mahendran, V. and Ramabadran, R. (2017) 'Analysis of controllers for the dynamic response enhancement of the three-port full-bridge DC-DC converter interfacing photovoltaic system', Int.