Iterative Adaptive Solar Tracking Having Variable Step Size

A system controller for position controlling a photovoltaic (PV) panel in a PV system including a power sensor sensing output power (P), and a motor for positioning the PV panel. The system controller includes a computing device having memory that provides motor control signal and implements an iterative adaptive control (IAC) algorithm stored in the memory for adjusting an angle of the PV panel. The IAC algorithm includes an iterative relation that relates P at current time k (P(k)), its elevation angle at k (?s(k)), P after a next step (P(k+1)) and its elevation angle at k+1(?s(k+1)). The IAV algorithm generates a perturbed power value P(k+1) to provide a power perturbation to P(k), and calculates a position angle ?s(k+1) of the PV panel using the perturbed power value. The motor control signals from the computing device cause the motor to oposition the PV panel to achieve ?s(k+1)

Method of adaptive solar tracking using variable step size

A method for controlling a photovoltaic (PV) panel in a PV system including a computing device that provides motor control signals and implements an iterative adaprtive control (IAC) algorithm for adjusting an angle of the PV panel. The IAC algorithm relates P at a current time k (P(k)), an elevation angle of the PV panel at k (0s(k)), P after a next step (P(k+1)) and an elevation angle of the PV panel at k+1 (0s(k+1)). The algorithm generates a perturbed power value P(k+1) to provide a power perturbation to P(k), and calculates 0s(k+1) using P(k+1). The motor control signals cause the motor to position the PV panel to achieve 0s(k+1). A change in P resulting from the positioning is compared to a predetermined change limit, and only if the change in P is greater than/equal to the change limit, again sensing P, and repeating the generating, calculating and positioning

A generalized program for extracting the control characteristics of resonant converters via the state-plane diagram

This paper presents a generalized computer program that can be used to derive the control characteristics of resonant converters from their state-plane trajectories. It has been shown that the geometrical properties of the state-plane trajectory can be used to derive the control characteristics of a given resonant converter topology. These characteristics are essential in determining the design parameters such as the converter gain, component stresses, and required feedback controller. The main program consists of several subroutines, each of which is associated with a segment of the state-plane trajectory. Such a program will make it faster and easier for a design engineer to obtain the design parameters of any given resonant topology

High Frequency Low Cost Dc-Ac Inverter Design With Fuel Cell Source For Home Applications

This paper presents a new design of high frequency Dc/Ac inverter for home applications using fuel cells or photovoltaic array sources. A battery bank parallel to the DC link is provided to take care of the slow dynamic response of the source. The design is based on a push-pull dc/dc converter followed by a full-bridge PWM inverter topology. The nominal power rating is 10 kW. Actual design parameters, procedure and experimental results of a 1.5 kW prototype are provided. The objective of this paper is to explore the possibility of making renewable sources of energy utility interactive by means of low cost power electronic interface

Adaptive Sun Tracking Algorithm For Incident Energy Maximization And Efficiency Improvement Of Pv Panels

In recent times, sun tracking systems are being increasingly employed to enhance the efficiency of photovoltaic panels by constantly tracking the elevation and azimuth angles of the sun. In this paper, a novel adaptive digital signal processing and control algorithm is presented that optimizes the overall PV system output power by adjusting the position angles of the solar panel on both the elevation and azimuth axes. Since the proposed approach is adaptive in nature, the optimal position angles for the solar panel are iteratively computed using the adaptive gradient ascent method, until the incident solar radiation, and hence the output power is maximized. Furthermore, a Taylor\u27s series approximation is employed for generating a unique optimal position angle increment/decrement at each iteration. Simulation results show that the proposed technique demonstrates fast convergence and excellent tracking accuracy at all times of the day. © 2010 Elsevier Ltd

Analysis And Optimization Of Bcm Peak Current Mode Control Techniques For Microinverters

This paper presents a detailed power loss model for a microinverter with three different zero voltage switching (ZVS) boundary conduction mode (BCM) current modulation methods. The model is used to calculate the optimum peak current boundaries for each modulation method. Based on the power loss model, a dual-zone modulation method is proposed to further improve the microinverter efficiency. The proposed modulation method provides two main benefits: the addition of one more soft switching transition and low peak current boundary. The additional soft switching transition reduces switching losses by means of zero current switching (ZCS). The lower peak current boundary reduces inductor rms current and conduction losses as well as allowing the output filter inductor to be smaller and more efficient. An improved BCM peak current control method was proposed and implemented on a microinverter prototype. The control circuit provides a highly accurate representation of the filter inductor current waveform and also provides galvanic isolation which simplifies control circuit design. The experimental results on a 400-W three-phase half-bridge microinverter validate the theoretical analysis of the power loss distribution and demonstrate that further improvement in efficiency can be achieved by using the proposed dual-zone modulation method

Clustering And Cooperative Control Of Distributed Generators For Maintaining Microgrid Unified Voltage Profile And Complex Power Control

To meet several power objectives, the idea of organizing DGs into several clusters in a microgrid is proposed in this paper. Power objectives include maintaining active power flow to the main grid at a predetermined level, minimizing the reactive power flow to the main grid and maintaining a unified voltage profile across the microgrid. DGs are organized differently for active and reactive power control. All DGs realize active power objective in one group. As reactive power is used to maintain the unified voltage, DGs are grouped in several clusters to regulate multiple critical point voltages. The closest cluster to the point of common coupling, minimizes the reactive power flow and others manage their reactive power to regulate their critical points. Each cluster has a virtual leader which other DGs follow, utilizing the cooperative control. The cooperative law is also derived, based on the dynamics of the inverters. © 2012 IEEE

Effects Of Circuit Nonlinearities On Dynamic Dead Time Optimization For A Three-Phase Microinverter

This paper investigates the effect of circuit component nonlinearities on dead time optimization for a three-phase microinverter with a peak current mode zero voltage switching (ZVS) output stage. The primary nonlinearities are those associated with MOSFET and other switching devices parasitic capacitance which may vary significantly as a function of the device operating voltage. In addition, filter inductor values vary as a function of operating current. The effect of the dynamic nature of these circuit components on inverter efficiency and dead time optimization is analyzed. Both calculated and experimental results are obtained using a 400-W three-phase half-bridge microinverter prototype

A Hysteresis Model For A Lithium Battery Cell With Improved Transient Response

In advanced battery management systems, it is critical to incorporate an accurate battery model that captures the cells\u27 dynamics in order to predict the battery performance. In this paper, a hysteresis model for a Lithium battery cell with improved transient response is proposed. In a battery cell, a hysteresis loop exists in a charge/discharge cycle resulting in an increased complexity in the cell behavior. The proposed model has the advantages of being simple and fairly accurate. The improvement in the transient response, which is observed during and after cell relaxation, has been verified experimentally by applying different charge and discharge tests data to the model. Model derivation and experimental verification are presented in this paper. © 2011 IEEE