Sumana Chowdhuri

Performance Studies of Fuzzy Logic Based PI-like Controller Designed for Speed Control of Switched Reluctance Motor

Switched reluctance motor (SRM) has gained significant interest in the field of industrial drive. The controller used to drive the machine is conventional PI controller. But the machine characteristics are very much nonlinear. This poses a problem for conventional controller design as regards to maintaining steady performance. There is also a need to adapt to the variable operating conditions. Fuzzy logic based heuristics is prospective since the exact analytical modelling of the system is difficult. PC implementation of the controller offers great flexibility in both design and maintenance phase. This work implements a PI like fuzzy logic controller (FLC) for SRM, which is found to work successfully in real time conditions. The work compares the performance of the FLC with respect to the conventional PI controller

Sample shifting technique (SST) for estimation of harmonic power in polluted environment

In this paper, an attempt has been made to estimate real and reactive power components for each harmonic in a polluted sinusoidal environment based on a newly proposed sample shifting technique (SST). A special feature of this technique is that each harmonic power component is estimated from the samples of voltage and current signals only, without measuring the power factor angle, or adopting FFT or DFT etc. as used by traditional methods. The present method also determines the DC power component along with the sinusoids. The method of SST is supported by simulation results along with experimental validation.

Development of an efficient photovoltaic MPPT Controller

A Maximum Power Point Tracking (MPPT) Controller using a buck converter has been designed and developed for a standalone Photovoltaic(PV) array. Perturb and Observe (P&O) algorithm has been implemented on a microcontroller to achieve the maximum power output from PV array. The whole developed hardware system has been tested with and without MPPT in a conventional PV array. The results show that the introduction of MPPT controller increases the efficiency of the conventional PV array.

GSM based condition reporting system for power station equipments

This work describes a condition based reporting system of Power plant components using GSM technology. In this present approach, a dedicated microcontroller based hardware unit (DHU) has been developed to continuously measure the parameters of the viz. voltage, current, speed of turbine, frequency of generation etc. of the alternator to monitor the running condition of it also. Other than the generator there are subsystems which also need continuous monitoring. In this monitoring system each equipment is connected with one such DHU which is also connected to a Global System for Mobile Communication (GSM) modem. The preliminary level of fault or abnormality in operation of each component is diagnosed by the respective DHU and the fault or abnormalities details are reported to the pre-assigned operator through an SMS service. In extreme case, the provision of equipment shut down by a return SMS is also provided. A proto-type laboratory model has been set up and is working satisfactorily.

Development of remote monitoring analysis and reporting system for industrial machines

This paper deals with the software development for a remote monitoring of industrial machines with the features of analysis of the machine data to detect any abnormality in their operations and generating a report according to this analysis. A set of software tools is thus developed for this diagnostic system with the primary objective is to detect any incipient faults those are being cropped up and are becoming severe with time. Motor Current Signature Analysis (MCSA), sequence component analysis etc. types of tool are utilized to detect any incipient fault. The front end GUI (Graphical User Interface) displays the running conditions of the machines of this multi-machine monitoring system along with a list of maintenance schedule while the back end Management Information Base (MIB) controls all the data collection, interfacing of GSM modem for sending SMS for the faulty machine information and sends the control action for the machine(s). Hybrid Data Compression scheme is utilized to make the system communication efficient as well as secured one. The developed system is tested with two/three machine in our laboratory.

A Study on Filter Design Aspects of Single-Phase Inverter with Various Modulation Schemes

This paper describes filter design aspects of single-phase inverter for its operation with either stand-alone or grid-connected mode of operation. The cutoff frequency of the filter is dependent on the switching frequency of the inverter switches as well as on the type of modulation. The value of the components of LC filter must be chosen to eliminate the higher order harmonics and to reduce the overall THD following the IEEE std.1547 guidelines. The design aspects of LC values following these rules for Bipolar and Unipolar modulation are studied and presented here.

Performance Evaluation and Filter Design Aspects of Single-Phase Inverter under Different Loading Conditions

ABSTRACT This paper describes the power quality issues at the output of an inverter. The role of a filter and its design aspects at the output of a single-phase inverter in order to minimize the different harmonic content associated with various modulation schemes is illustrated. The relationship of the cut-off frequency of a second-order filter along with the switching frequency as well as on the type of modulation is established. The procedure to choose the values of L and C components of LC filter to reduce the overall THD following the IEEE std.1547 is also illustrated. The performance of the total system for different linear and non-linear loading conditions along with variations in input voltage and output loading is evaluated. The entire system and its performance is verified using MATLAB-based simulink models and satisfactory results are obtained. Abbreviations: CT: current transformer; MI: modulation index; MPWM: multi pulse width modulation; PI controller: proportional integral controller; PR controller: proportional-resonant controller PWM: pulse width modulation; SPWM: sinusoidal pulse width modulation; THD: total harmonic distortion; VT: voltage transformer

Performance analysis of a three-phase Active Front-End PWM Rectifier without current loop PI controller

This work investigates the performance of an Active Front-End (AFE) Rectifier with direct and quadrature axis current control method. Most of the research works describe that the controller for an AFE Rectifier requires three Proportional-Integral (PI) controllers to regulate DC voltage, d-axis and q-axis current. Normally, the outer loop for DC voltage control requires high gain value to stabilize the DC voltage and the inner loop for current control requires low gain values to regulate the current. In this proposed work, due to lower gain of the inner current loop, the PI controllers for that specific loop has been omitted to deal with the easy control of the controller.

Synchronization aspects of single phase SPWM inverters for microgrid mode of operation

This paper deals with inverters which are to be synchronized to share the common load of microgrid. The microgrid under consideration is in OFF grid condition and hence one of the inverters is designed as master and the remaining are designed for slave mode of operation. A state-of-the-art synchronization strategy is developed for the initial synchronization of the inverter during startup period. The microgrid synchronism is then maintained with this master-slave configuration of inverters and the amount of load that can be fed to the microgrid, is adjusted or decided by the user. The control strategy is so designed that the load can always be fed at unity power factor. The SPWM technique and an output filter are utilized to reduce the voltage harmonics to a minimum level and thus produce an almost sinusoidal terminal voltage. The entire design is simulated with MATLAB Simulink and the desired output is achieved.

A comparative study between different modulations techniques used in field oriented control induction motor drive

In industries, where adjustable or variable speed drives are required, induction motor drives are chosen with various control strategies to have fast flux and torque response. In order to overcome sluggish response of induction motor and to have decoupled flux and torque characteristics, field oriented control (FOC) is implemented. These drives consists of voltage source inverters with various modulation schemes like SPWM, THISPWM, SVM etc. in order to minimize the harmonics present in the output voltage or current. Presence of harmonics makes the response non-sinusoidal and generate heating, torque pulsation etc within the machine. But for field oriented control induction motor drives, selection of efficient modulation scheme is important as machine current is controlled and in this current loop presence of ripples may create multiple zero crossing problems in the SPWM. In this paper, different modulation schemes are investigated and their performances are compared for a variable speed three phase FOC Induction motor. This system is modeled in MATLAB and SIMULINK where all the above stated modulation schemes are implemented. It is observed that the FOC based IM drive gives better result when subjected to Space Vector Modulation Scheme.