Mukesh Kumar Pathak

Power conditioning system for solar power applications: Closed loop DC-DC convertor fed FPGA controlled diode clamped multilevel inverter

The main objective of this paper is to develop a power conditioning system, which can be used to extract the variable solar DC power from sun and convert it into AC power to feed a 3-phase AC load effectively. This paper presented the simulation results of Photovoltaic (PV) power conditioning system for three phase AC loads. The conditioner consists of a diode clamped three level inverter fed by closed loop voltage controlled DC-DC Boost converter. This closed loop control of DC-DC converter is implemented by a conventional Pulse Width Modulator (PWM) in duty cycle ratio control method. This boost converter is designed to obtain regulated voltage from the variable solar power. A level shift sinusoidal PWM is used to control the multilevel inverter on FPGA.

An improved two-stage non-isolated converter for on-board plug-in hybrid EV battery charger

This paper presents a single-phase two-stage non-isolated converter for on-board plug-in hybrid electric vehicle battery charger. The first stage is a conventional boost converter and the second stage is a bi-directional dc-dc converter (battery-interface) having a wide range of output voltage with low component stress in both directions compared to conventional SEPIC, Cuk, Zeta and inverting buck-boost converters. In addition, the second stage bi-directional dc-dc converter also has improved efficiency over two switches non-inverting buck-boost converter) in the buck mode from one-direction and in boost mode from another direction. Simulation results are given to demonstrate the effectiveness of the proposed system.

Effect of Non-Idealities on the Design and Performance of a DC-DC Buck Converter

In this study, the performance of a direct current (DC)–DC buck converter is analyzed in the presence of non-idealities in passive components and semiconductor devices. The effect of these non-idealities on the various design issues of a DC–DC buck converter is studied. An improved expression for duty cycle is developed to compensate the losses that occur because of the non-idealities. The design equations for inductor and capacitor calculation are modified based on this improved expression. The effect of the variation in capacitor equivalent series resistance (ESR) on output voltage ripple (OVR) is analyzed in detail. It is observed that the value of required capacitance increases with ESR. However, beyond a maximum value of ESR (r c,max ), the capacitor is unable to maintain OVR within a specified limit. The expression of r c,max is derived in terms of specified OVR and inductor current ripple. Finally, these theoretical studies are validated through MATLAB simulation and experimental results.

Enhanced power quality based single phase photovoltaic distributed generation system

ABSTRACT This article presents a novel control strategy for a 1-ϕ 2-level grid-tie photovoltaic (PV) inverter to enhance the power quality (PQ) of a PV distributed generation (PVDG) system. The objective is to obtain the maximum benefits from the grid-tie PV inverter by introducing current harmonics as well as reactive power compensation schemes in its control strategy, thereby controlling the PV inverter to achieve multiple functions in the PVDG system such as: (1) active power flow control between the PV inverter and the grid, (2) reactive power compensation, and (3) grid current harmonics compensation. A PQ enhancement controller (PQEC) has been designed to achieve the aforementioned objectives. The issue of underutilisation of the PV inverter in nighttime has also been addressed in this article and for the optimal use of the system; the PV inverter is used as a shunt active power filter in nighttime. A prototype model of the proposed system is developed in the laboratory, to validate the effectiveness of the control scheme, and is tested with the help of the dSPACE DS1104 platform.

PI controller design of a dc-dc Zeta converter for specific phase margin and cross-over frequency

Dc-dc Zeta converter is a buck-boost type of converter, which yields dc output voltage with same polarity that of the input voltage. It is widely used in various domestic and industrial applications. For good voltage regulation, fast dynamic response, and stable operation of this converter, a feedback control design is necessary. Therefore, in this paper, the duty cycle to output voltage small-signal transfer function of dc-dc Zeta converter is obtained using state-space technique and Leverrier algorithm. Then this transfer function is used for designing a PI controller using stability equations to meet specific phase margin and desired cross-over frequency. The simulation results display that compensated Zeta converter exhibits good dynamic and steady-state behavior in presence of line and load variations.

An improved power converter for standalone Photovoltaic system

As the availability of solar energy varies widely with time and with different atmospheric condition, the cascaded multilevel inverters generates distorted output ac voltage and current if the generated PV voltages of each PV module are unequal. This paper proposes a novel space vector modulation technique for the single-phase cascaded H-bridge multilevel inverter (CHBMLI) to generate a balanced output voltage even under partial shadow condition of Photovoltaic (PV) module. In this topology each H-bridge cell of CHBMLI is connected to an individual PV module through a buck type DC-DC converter. This topology permits independent control of each PV module to operate them at maximum power point. It also offers other advantage such as lower current ripple compared to standard two-level topologies. The simulink model is developed using simpowersystem and simulink toolbox of MATLAB.

Neuro-fuzzy-based torque ripple reduction and performance improvement of VSI fed induction motor drive

An indirect vector control is used in various industrial induction motor drives for better dynamic performance. But the performance of closed-loop controlled induction motor drive is largely influenced by the type of current controllers used. Usually, proportional-integral (PI)-based current controllers are used due its simplicity. But these PI controllers suffer from tuning problem. To overcome the problem, this paper presents adaptive neuro-fuzzy (ANFIS)-based current controllers for indirect vector controlled VSI fed induction motor drive in order to minimise the torque ripple. The proposed ANFIS controller significantly reduces the torque ripple compared to that of conventional PI controllers without using any filter. In this, the current command values and actual values of current are fed to the ANFIS-based controllers and the controller is trained based on the obtained values. The performance of the indirect vector controlled induction motor drive has been simulated at different operating conditions using the ANFIS controller and the obtained results are compared with PI controller. Additionally in the implemented SVM algorithm, the switching times proportional to the instantaneous values of the reference phase voltages. It eliminates the need the calculation of sector and angle information unlike conventional SVM method.

A multi-device front-end power factor converter for EV battery charger

This work presents a front-end a novel boost power factor converter for on-board plug-in electric vehicle battery charger. The converter has lower passive components size such as inductor and EMI filter. In addition, low switch stress and higher efficiency can be expected. As a result, the size of charger, charging time and cost of electricity is minimized. In addition, a detailed current stress model of this topology is presented for selection of power stage components as well as for efficiency calculation. The proposed converter is simulated in Matlab/Simulink environment to demonstrate its effectiveness.

Parallel Stator Resistance Estimator Using Neural Networks for Rotor Flux Based Model Reference Adaptive System Speed Observer

Abstract Model reference adaptive system schemes offer simpler implementation and require less computational effort compared to other speed sensorless methods. The performance of rotor flux based model reference adaptive system schemes at low-speed operation is poor because of parameter sensitivity and presence of the integrator in the reference model. As stator resistance inevitably varies with temperature, for accurate operation at low speeds, an appropriate online identification algorithm for the stator resistance is required. In this article, a neural network based parallel stator resistance and rotor speed estimator has been proposed to simultaneously rectify the limitation of model reference adaptive system schemes, i.e., stator resistance variation and DC offset due to integrator, employing a neutral network in stator resistance estimator and modifying the reference model by adding a compensating voltage term. An indirect sensorless vector control scheme has been simulated and experimentally validated using the dSPACE DS-1104 R&D controller board (dSPACE GmbH, Paderborn, Germany) to verify the performance of drives at different operating conditions.

Rotor flux based MRAS for sensorless operation of three level inverter fed induction motor

This paper proposes a sensorless vector control scheme for induction motor to operate at low speed. The integrator in the reference model of the rotor flux based Model Reference Adaptive System (MRAS) have the problems of dc drift and dead time. A new integration algorithm is developed for rotor flux based MRAS to reduce the effects of integrator. Multilevel inverter with space vector modulation technique is used to improve the performance of induction motor drive. Simulation study is carried out using SIMULINK and comparison study is made between classical rotor flux MRAS, new integration algorithm.