B. L. Narasimharaju

Coupled inductor bidirectional DC-DC converter for improved performance

Energy storage is the major concern in smart micro grids like in renewable power generation, electric vehicles and small scale DC-UPS systems. This paper proposes analysis, and voltage mode control of coupled inductor bidirectional converter. Unfortunately, switches of four and beyond in isolated schemes increase production costs and reduce conversion efficiency, and non-isolated topologies suffer from high voltage/current stress. As compared with the counterparts of conventional converter topologies, the proposed converter has the merits of less component count, high efficiency, and smaller size. The high voltage diversity enables a battery module of low voltage to be interfaced with the high-voltage dc bus or the micro grid for subsequent utilization. The battery fed bidirectional converter with controller to regulate the DC link voltage and battery charge voltage is implemented in the Simulink/Matlab environment. Also, experimental confirmation of the proposed converter is shown.

Voltage mode control of coupled inductor bidirectional DC to DC converter

In this paper, authors propose a coupled inductor bidirectional converter, and design of classical PI controllers in voltage mode control. The proposed converter has the high voltage diversity which enables battery module of low voltage to be interfaced with the high-voltage dc bus or the micro grid for subsequent utilization. The working principles, design guidelines, and PI based voltage controller design of the proposed converter is discussed in detail. Theoretical principles of battery fed converter with voltage controller are validated through simulation in the Matlab/Simulink environment. Also, prototype coupled inductor BDC converter is developed and performances are evaluated.

Two-quadrant clamping inverter scheme for three-level open-end winding induction motor drive

This article proposes a space-vector based pulse width modulation (SVPWM) scheme for a three-level dual-inverter-fed open-end winding induction motor drive. The proposed method introduces clamping of one inverter for 180° span of the rotation of the reference space vector. The proposed scheme neither requires sector identification nor lookup tables for the generation of the gating pulses. The switching pattern adopted in the present work ensures alternative clamping and switching modes every 180° for both the inverters. In the present scheme, the zero sequence currents are denied a path by using isolated power supplies. The proposed switching strategy envisages two-quadrant clamping of the inverters which results in lowering of the losses that occur in power electronic switches. Simulation studies have been carried out for the proposed SVPWM strategy using MATLAB/Simulink.

Intelligent technique for improved transient and dynamic response of bidirectional DC-DC converter

This paper aim to design a intelligent technique for BDC converter. The converter contains non-linear elements making the mathematical model more complex which instigate the use of FLC. The nature of FLC has adaptive characteristics that can achieve robust response to a system with uncertainty, parameter variation, and load disturbance. In order to see the advantages of FLC, classical PI control has applied to the BDC converter under same circumstances and has been compared. Simulation results demonstrate that the converter can be regulated with good dynamic performance irrespective to input disturbance and load variation. The presented FLC approach can be applied to any DC-DC converter topologies.

Switched Reluctance Machine for Off-Grid Rural Applications: A Review

ABSTRACT Switched reluctance machine (SR-machine) has emerged as an attractive option for variable speed drives due to its several advantages: simple and rugged construction, high efficiency, high torque-to-inertia ratio and thermal robustness. It is economical to use without the hassles of winding and permanent magnets on rotor. Therefore, this paper presents a comprehensive review of SR-machine drive, modelling, converter topologies, control and its suitability for off-grid small-scale rural (SSR) applications using alternative energy sources (AESs). In particular, SR-machine operations such as SR motor (SRM) for photovoltaic (PV) water pumping system (WPS) and SR generator (SRG) for variable speed wind energy conversion systems (WECSs) are presented. In addition, suitability of SRG-based hybrid PV-wind energy system has been analyzed and its advantages are discussed.

Parasitic effect considerations in modeling of CI-BDC converter and its voltage controller

This paper emphasize on the investigation of smallsignal behavior of a Coupled Inductor Bidirectional DC-DC (CI-BDC) converter being controlled by a Voltage Mode Control (VMC) technique. The small-signal model including converter parasitics is derived using the SS averaging technique. This linearised converter modeling makes the design of closed loop controller much easier. The closed loop model has also been developed and simulated using SIMULINK/MATLAB software. The parasitic effects on stability and closed loop regulation have been made extensively. Simulation results of closed loop controlled CI-BDC converter show the good regulation and stability over wide range of load variations. The analyses show that the proper consideration of parasitics is also a very important for controller design.

A Cost-Effective Zero-Voltage Switching Dual-Output LED Driver

Coupled-inductor (CI) converters are widely used in the light-emitting diode (LED) lighting applications due to several advantages, such as high step-down conversion, reduced switch/diode stress as compared to conventional buck converters. However, the main drawback of CI buck converter is high-voltage spikes during turn-OFF instant due to the leakage inductance of a CI, which leads to switching device failure. Passive clamp circuits are used to overcome the leakage inductance problem, but these clamp circuits results in reduced efficiency and increased cost. This paper proposes a high step-down zero-voltage switching dual-output coupled-inductor buck (ZVS-DOCIB) LED driver with dimming control. The proposed LED driver provides various advantages like high step-down conversion, effective recovery of leakage energy, elimination of voltage spikes, reduced switching loss due to ZVS operation of both the switching devices, and less switching device count, particularly for multioutput drivers. Also, ZVS operation provides a significant reduction in switching losses, which results in high efficiency. Furthermore, dimming control is studied to regulate the average output currents. This paper presents design and analysis of the proposed ZVS-DOCIB converter. A prototype of the converter has developed and validated experimentally with simulation counterparts.

Essence of variable DC PWM control for switched reluctance motor in direct PV-fed water pump

Switched reluctance motor (SRM) has emerged as an viable option in variable speed drives because of its various benefits such as high power density, high efficiency, and thermal robustness. Without the winding or permanent magnets on rotor makes it cost effective. This paper presents essence of Variable DC (VDC) PWM based control for SRM in Direct PV-fed Water Pumping System (WPS). The technique provides reduction in noise due to reduced current gradients during commutation as compared to angle control strategy. In addition, current sensors used in hysteresis control and intermediate DC-DC converter for MPPT are eliminated which results in reduced costs. A Matlab/Simulink look-up table simulation model is developed using experimentally determined flux data to study the effect of proposed system on phase currents and duty cycle is presented. The control is implemented using FPGA Spartan 3AN board. The results ofsimulation and implementation validate the control and are found in agree.

Optimized dual active bridge Bi-directional DC-DC converter for UPS application

With the growing emphasis on smaller compact and efficient power system there is increasing interest in the possibility of using Bi-directional converters especially in DC based power applications. Having the capability of bilateral power flow, that provides the functionality of two uni-directional converters in single converter unit; Bidirectional converters have the increased industrial applications; demand optimized study of topologies and feasibility, critical feature study for the considered application. This document suggests an optimized implementation of Bidirectional DC-DC converter to fit the present day UPS application. Key issues like compact design, utilisation of transformer core, optimised topology for low power (2.5kW) applications were discussed.

Modelling and stability analysis of coupled inductor bidirectional DC-DC converter

This paper emphasizes on the small-signal behavior and stability analysis of bidirectional DC to DC converter. The bidirectional current capability of the switch eliminates the discontinuous conduction mode which leads to a simple analytic description of the switching converter. The small-signal model is considered to design the control parameters. The transient, stability analyses and closed loop regulation have been studied extensively. The closed loop model has also been developed and simulated using Matlab/Simulink environment. The closed loop performances of the converter are evaluated for wide range of load conditions.