Dipankar Mukherjee

Ground leakage current elimination in a transformerless unipolar modulation based single phase grid-connected photovoltaic system

Unipolar sinusoidal pulse width modulation (SPWM) full-bridge inverter poses advantages such as higher dc voltage utilization, smaller current ripple in the filter inductor, and higher processing efficiency. However, unipolar SPWM full-bridge inverter causes time varying common-mode voltage. The variable common-mode voltage excites leakage current through the parasitic capacitance between the PV array and the ground, which restricts its application in transformerless grid-connected photovoltaic (PV) inverter. In order to solve this problem, an optimized full-bridge topology is proposed in this paper. The topology uses an additional branch to be clamped the potential of the freewheeling path to the half of the input voltage in the freewheeling period, which guarantees no variable common-mode voltage in the unipolar SPWM full-bridge inverter. The proposed topology poses advantages such as higher efficiency, simple switching, and topological simplicity as compared to existing topologies. The proposed topology has been verified in MATLAB/Simulink environment with satisfactory results.

Modelling and simulation-based performance study of a transformerless single-stage grid-connected photovoltaic system in Indian ambient conditions

This paper presents a transformerless single-stage full-bridge inverter for a grid-connected photovoltaic system (GCPVS) and its performances based on power loss, efficiency, and total harmonic distortion for the conditions: (a) seasonal variations of inputs in the photovoltaic (PV) system, (b) variation of grid voltage, and (c) variation of carrier frequency and Modulation Index of sinusoidal pulse-width modulation of the inverter. A typical 2.8 kWp, 368 V nominal PV array-based GCPVS is modelled and simulated to evaluate proper load matching in Indian ambient and grid conditions prior to practical implementation. Detailed analyses on system powers, power losses, efficiency, and harmonic distortions as well as selection of parameters for the simulation model are presented. The impacts of penetrating PV power into electric grid are investigated in order to predict the possible unwanted consequences.

A dsPIC based novel digital sinusoidal pulse-width modulation technique for voltage source inverter applications

Abstract This paper presents a novel digital sinusoidal pulse-width modulation (SPWM) technique based on immediate calculation of duty cycle count (DCC) values of pulses with high speed Harvard architecture based RISC controllers. The DCC values are calculated with the multiplication of an instant modulation index count (MIC) and a preloaded sine count value (SCV) table in the program memory of the controller. The proposed technique overcomes the drawbacks of overhead time in digital carrier-reference based technique and large memory requirement in look-up table technique. The proposed technique is effective where frequent change of modulation index (MI) of SPWM is essential like grid-connected inverter applications. The effectiveness of the proposed technique is verified with both Proteus VSM based simulation and dsPIC based experiment.

An embedded monitoring unit for a lead-acid battery with reference to a PV system

Most significant Balance of System (BOS) unit for monitoring health of a Photovoltaic (PV) system is the power Conditioner unit. Here, authors propose incorporation of an additional controller unit for monitoring all possible states of the Battery-bank leading to an enhanced energy security mechanism for small decentralized PV applications.

A standalone charging station for Li-ion digital camera battery from solar photovoltaic module with supercapacitor

A simple standalone charging station for lithium ion digital camera battery is presented in this paper. This charging station utilizes non-renewable solar energy to charge supercapacitor, as an energy storage device, which in turn charges the Li-ion battery of the digital camera. The supercapacitor charges and discharges very fast compared to normal battery and it utilizes the stored energy to supply the load in the absence of sunlight. This charging station can be replicated in public places like bus stops, railway platforms, petrol pumps, workplaces and remote villages where the electricity supply is not adequate.

A dsPIC based efficient single-stage grid-connected photovoltaic system

Compared to multistage, single-stage grid-connected photovoltaic system (GCPVS) has advantages such as topological simplicity, smaller size, high efficiency, etc. However, complexity in monitoring and controlling scheme is much increased as functions such as maximum power-point tracking (MPPT), synchronization and load sharing with the grid, etc. need to be considered simultaneously in same stage. A high performance dsPIC based single-stage GCPVS performing aforementioned functions simultaneously by adjustment of inverter output voltage phasor with respect to the grid voltage, is presented. Only AC quantities (inverter output voltage and current, grid voltage) sensing and monitoring are required in the proposed system. The proposed system poses advantages over existing single-stage systems such as more topological simplicity, less system components, better performance, reduced size and weight, etc. Variations of both photovoltaic (PV) generation and grid voltage are considered in load sharing in the proposed system. Simulation results validate acceptability of the system.