Ashok Jhunjhunwala

The limitations of the conventional MPPT technique are oscillations of the system at steady state leading to energy loss, slower response and the occurrence of drift. A simple zonal based MPPT controller is proposed in this paper which addresses the above limitations without additional requirement of sampling or sensors apart from the basic voltage and current sensors. The proposed system is simple, cost effective and easy to implement. Phase shift reference (Duty) for the DC-DC converter is varied dynamically by the proposed MPPT controller depending upon the operating point voltage to have a better dynamic response. The error in the perturbation direction, if any, is corrected by the controller while computing the change in duty reference ΔD). This ensures the drift free operation. The response speed of the proposed controller is improved compared to the conventional controller by having a variable step size. Solar PV fed full bridge series resonance DC-DC converter with resistive load is considered for evaluating the proposed control scheme. The performance of the proposed MPPT control technique is verified by simulations and hardware results.

The limitations of the conventional MPPT technique are oscillations of the system at steady state leading to energy loss, slower response and the occurrence of drift. A simple zonal based MPPT controller is proposed in this paper which addresses the above limitations without additional requirement of sampling or sensors apart from the basic voltage and current sensors. The proposed system is simple, cost effective and easy to implement. Phase shift reference (Duty) for the DC-DC converter is varied dynamically by the proposed MPPT controller depending upon the operating point voltage to have a better dynamic response. The error in the perturbation direction, if any, is corrected by the controller while computing the change in duty reference ΔD). This ensures the drift free operation. The response speed of the proposed controller is improved compared to the conventional controller by having a variable step size. Solar PV fed full bridge series resonance DC-DC converter with resistive load is considered for evaluating the proposed control scheme. The performance of the proposed MPPT control technique is verified by simulations and hardware results.

Power converters operating from solar PV array are typically operated in maximum power extraction mode, by the use of MPPT algorithms. Besides MPPT, buffering needs between PV and loads may require battery storage as well. Storage is expensive and also requires periodic maintenance and replacement. In this work, solar PV powered BLDC fans are developed without the use of storage and studied for their suitability in day time use like offices, schools, colleges. Two modes of operation are devised for operation of the fan- MPPT mode and Speed Regulation (SR) mode. In order to keep cost of the fan low, the optimal MPPT strategy to be used is determined from simulations. Hardware implementation is carried out to determine the actual operation of the system with respect to daily solar irradiation changes. From the experimental results it is seen energy efficient operation of BLDC motor drive, compared to single phase AC motor driven fan are achieved while keeping the scheme simple and cost low.

With the increasing use of power electronics in all types of appliances, and with the increasing penetration of solar PV, distribution of power in the DC form is becoming attractive. This paper brings together various concerns that have been expressed in DC distribution at low voltages for consumption in domestic and other building needs. The paper presents various arguments and attempts to arrive at a solution from various points of view. A suitable voltage level of 48 V, and a suitable distribution scheme are presented along with some field experiences of installation of such systems.

Photovoltaic powered pumps are becoming popular. Their operation differs from that of the AC Mains powered pump, as they work under varying input power conditions. The efficiency figures of different subsystems will keep changing due to varying solar radiation conditions, causing the variations in overall efficiency under partial load operating conditions of the pump. The aim of this work is to study the performance of the various subsystems under these operating conditions. The system developed here consists of a Photovoltaic (PV) array of 900 Wp with 72 V nominal DC bus, a DC to DC Converter, a Variable Frequency Drive (VFD) and a three phase induction motor driven submersible pump. Maximum Power Point Tracking (MPPT) algorithm has been developed and implemented to maximize the use of PV power generated at any given instant. The system was installed and tested at Indian Institute of Technology Madras in Chennai, where daily average Peak Sun Hours is 5.6. Ambient temperature, total pressure head, water flow and power levels at different points starting from the output of the PV array upto the electrical power equivalent of water delivery were determined under varying solar radiation levels from sunrise to sunset. Continuously varying power efficiency figures of the subsystems were determined and power budget prepared. Wire to Water Energy Efficiency figures as well as System Performance Indices were determined. © 2013 IEEE.