Showing papers on "Variable-frequency drive published in 2021"

An Enhanced Linear Active Disturbance Rejection Controller for High Performance PMBLDCM Drive Considering Iron Loss

Abstract: The use of position sensors for the variable frequency drive (VFD) has been verified for years. However, more reliable VFDs with smart autonomous systems require side-by-side implementation of sensor and/or sensorless operation. Recently developed active disturbance rejection control (ADRC) provides robustness to VFD uncertainty and its fast response to reject disturbances. Considering the iron loss effect as the disturbance to the permanent magnet brushless dc motor (PMBLDCM) performances, a novel ADRC is proposed in this article. The ADRC current controller considering the iron loss effect is proposed along with an estimation of the back electromagnetic force disturbance used for the position/speed estimation. The proposed controller incorporates a structured inner and outer closed-loop ADRC that considers process delays and extended state observer dynamics. These dual ADRC-based control algorithms are verified for PMBLDCM drive both by simulation study and experimental findings. The improved performance of the proposed method is validated with a laboratory prototype of 2.5 kW PMBLDCM drive system.

Effects of Current Distortion on DC Link Inductor and Capacitor Lifetime in Variable Frequency Drive Connected to Grid With Active Harmonic Filter

Abstract: In this research article, new investigation and comprehensive analysis is done on the current distortion effects of dc link inductor and capacitor in variable frequency drive (VFD). Shunt active filter (SAF) is the most prominent solution for harmonic mitigation at the point of common coupling in the power distribution system. However, SAF connectivity reduces the grid impedance ( ZTH ) seen at the input of six pulse diode bridge rectifier in VFD. Commutation behavior of the diode rectifier is changed due to this grid impedance variation resulting in increased harmonic current distortion (THD i ) at the input of the rectifier bridge. This effect increases the ripple current of dc capacitor, dc link inductor losses, and diode rectifier conduction losses. This study investigates the drive dc link inductor and capacitor lifetime reduction with and without SAF, under various grid operating conditions of 3% voltage unbalance and 8% predistortion. Moreover, the high frequency (2–9 kHz) impact on dc link inductor core and copper losses is detailed. A 250 kW VFD with SAF of 180 A capacity is used for test measurement under various operating conditions. Current distortion effects are analyzed, and test results are compared with MATLAB simulation. Grid impedance variation due to SAF and its effect on the reliability of the VFD front-end components were not covered in detail in any of the earlier research. Lifetime estimation of dc link inductor and capacitor due to grid impedance variation is one among the significant outcomes of this investigation.

Dual Rotor Axial Flux Permanent Magnet Motor using PCB Stator

Abstract: This paper presents a framework for the design and analysis of a light and low-cost axial flux permanent magnet motor which consists of dual permanent magnet rotors and a coreless Printed Circuit Board stator. Removal of the conventional laminated stator core significantly reduces core losses, decreases cogging and torque ripple and increases efficiency. The proposed design drastically eliminates magnetic forces between the rotor and the stator as well as the torque ripple, hence reduces the acoustic noise. A fully integrated variable frequency drive is proposed which uses high efficiency silicon carbide MOSFET inverter design. Using Printed Circuit Board stator enables simpler and faster manufacturing. An in-house analytical simulation has been used to model the motor design and evaluate the performance. The proposed design has been manufactured and was tested successfully. Finally, the test results are compared with the simulation results as well as finite element analysis.

Performance Enhancement of Line Start Permanent Magnet Synchronous Motor With a Special Consequent Pole Rotor

Abstract: This paper presents the development of line start permanent magnet synchronous motor (LSPMSM) employing a special consequent pole rotor. The proposed rotor structure uses both circumferentially magnetized spoke shape and radially magnetized arc shape magnets. The combination of spoke and arc shape is arranged to provide consequent magnetic poles. This new rotor structure improves the motor performance and consumes less magnet volume. The time-stepping finite element analysis (FEA) is used to evaluate transient and steady state performances. Extensive simulation studies are performed to establish the supremacy of proposed rotor structure over benchmarked spoke and some other known rotor structures. For experimental validation, prototypes of machine are built using (a) proposed magnet configuration, and (b) spoke type configuration having circumferentially magnetized magnets which is used as baseline motor. Rigorous experimental studies are carried out and it is observed that the proposed structure offers 4% improvement in the full load efficiency over the benchmarked spoke rotor LSPMSM yet by saving 10% magnet volume. Further, it is observed that the performance of the proposed machine is enhanced for direct online (DOL) as well as variable frequency drive (VFD) fed supply operation.

Fault Diagnosis for Variable Frequency Drive-Fed Induction Motors Using Wavelet Packet Decomposition and Greedy-Gradient Max-Cut Learning

Abstract: In this paper, a novel fault diagnosis method for variable frequency drive (VFD)-fed induction motors is proposed using Wavelet Packet Decomposition (WPD) and greedy-gradient max-cut (GGMC) learning algorithm. The proposed method is developed using experimental stator current data in the lab for two 0.25 HP induction motors fed by a VFD, subjected to healthy and faulty cases under various operating frequencies and motor loadings. The features are extracted from stator current signals using WPD by evaluating energy eigenvalues and feature coefficients at decomposition levels. The proposed method is validated by comparing with other graph-based semi-supervised learning (GSSL) algorithms, local and global consistency (LGC) and Gaussian field and harmonic function (GFHF). To enable fault diagnosis for untested motor operating conditions, mathematical equations to calculate features for untested cases are developed through surface fitting using features extracted from tested cases.

Sliding Mode Observer based Rotor Position Estimation with Field Oriented Control of PMBLDC Motor Drive

Abstract: A sensorless field-oriented control of PMBLDCM based on sliding mode observer is presented. FOC is a technique for regulating torque in variable frequency drive. A modified sliding-mode observer has been designed for field-oriented control of PMBLDCM powered by a voltage-source inverter in order to accomplish speed control of drives. The disturbances have been estimated taking the load torque and viscous friction coefficient into account. This article demonstrates the PMBLDCM drive sensorless FOC in two-phase operating mode to achieve torque control. Provided with the proposed algorithms, such observer is beneficial in reducing the rotor position estimation error for variable speed drives. The implemented sensorless control algorithms are implemented and evaluated in a hardware prototype. The simulation and experimental findings are presented to demonstrate the efficacy of the strategy developed.

Choosing variable-frequency drive systems for the mining process units

Abstract: Mining enterprises are energy intensive facilities. The capacity of single technological units can reach 5 MW. Variable-frequency drive systems are often used to set them in motion. The paper analyzes the features of choosing and using variable-frequency drives under diamond mining conditions. The study objective is to formulate and formalize the problems of introducing and operating variable-frequency drives at diamond-mining enterprises to further develop and implement guidelines for improving the performance of this drive type. To achieve this objective, the use of variable frequency drives in various process units of diamond mining should be studied and analyzed. The units are considered, for which in recent years, electric drive systems have been groundlessly (according to the authors) chosen by the engineering staff of enterprises. A technical and economic comparison of low-voltage frequency converters with the same power but different control modes is performed. The economic indicators of introducing high-voltage and low-voltage frequency converters into an existing electric drive system are calculated and represented as a comparative table. Conclusions are made on the need to proceed with the research and develop guidelines for implementing frequency converters at diamond-mining enterprises.

An ANOVA-Based Fault Diagnosis Approach for Variable Frequency Drive-Fed Induction Motors

Abstract: In this article, an analysis of variance (ANOVA)-based fault diagnosis approach using experimental data is proposed for variable frequency drive (VFD)-fed induction motors Line-to-neutral voltages at the motor terminal and the stator currents, measured from two identical 025 HP three-phase squirrel-cage induction motors fed by a voltage source inverter-based low-voltage VFD under healthy and faulty cases, are evaluated Harmonic spectra of the measured voltage and current are obtained by Discrete Fast Fourier Transform (DFFT) Through the coherence and magnitude consistency analysis, the fundamental and 5th harmonic of the stator current are chosen as “signature frequency components” ANOVA along with the multiway analysis are then applied to signature frequency components, their mean and standard deviation are identified as “fault signatures”; and the p -value from the inter-group analysis of the mean and standard deviation is used to classify faults To facilitate fault diagnosis for untested motor operating conditions, formulas to calculate fault signatures are derived by surface fitting using tested data

Two Level AC-DC-AC Converter Design with a New Approach to Implement Finite Control Set Model Predictive Control

Abstract: Due to various applications of variable frequency drives in industry, design procedure and control methods of these converters have attracted many researchers from both industry and academia. In this paper, a high power density AC-DC-AC converter design is presented alongside finite control set model predictive control method. Using model predictive control for the LC filter at the load side enables load voltage control which is an important issue in variable frequency drive applications. Also, input, output, and DC link filters’ design methods are presented and the results are compared to the designed filters in the literature. The comparison shows significant filter size decrease by using presented approach. Applying the proposed control method to the AC-DC-AC converter brings benefits such as simple implementation, robustness to the load changes, and fast dynamic response compared to conventional control methods. Finally, to demonstrate the effectiveness of the proposed design and control method, the designed variable frequency drive has been simulated and the results are presented.

Thermal Characterization of SiC Modules for Variable Frequency Drives

Abstract: Silicon carbide (SiC) devices can exhibit simultaneously high electro-thermal conductivity and extremely fast switching. To perform optimal designs showing the benefits of SiC in achieving efficiency, size, weight, and cost objectives for electric converters design, it is necessary to establish better models for calculating device losses and an efficient thermal model that can be calibrated to consider the nuances of measurement based thermal equivalent circuits. This work's outputs can be used in a power converter multi-objective optimization process or real-time temperature prediction of drives to improve reliability and maximize performance. The proposed modified loss calculation and thermal model demonstrate the SiC power module's advantages to reduce peak junction temperature and power cycling effects. A detailed power loss calculation and thermal model is developed and tested on a 480 V, 186 A, 150 HP variable frequency drive (VFD) with SiC modules. A comparison between the SiC module and an equivalent rated Si module demonstrates the reduction in power cycling effects, particularly at low-speed operation. Infrared (IR) imaging results and analytical explanations of the phenomenon is provided. Power cycle tests show that higher thermal conductivity is not the only reason contributing to the lower temperature ripple in low-speed operation.

Experimental study of the VFD’s speed stabilization efficiency under torque disturbances

Abstract: The article presents a technique for experimental research of variable frequency drives experiencing periodic torque disturbances of variable frequency. The technique is based on the nonlinear transfer function of a link of an asynchronous electric motor, which forms an electromagnetic torque, proposed in previously published articles. The dependence of the transfer function on the frequency of the stator voltage and slip determines the research methodology. Experiments have shown the advantage of the dynamic characteristics of a drive with a positive feedback on the stator current over electric drives with traditional control methods (vector and scalar sensorless), and in terms of dynamic characteristics they also exceed drives with a vector control closed in motor speed. These advantages are retained when the frequency of change of the disturbing torque is changed from 0 to 5 Hz.

The experimental identification method of the dynamic efficiency for frequency regulation algorithms of AEDs

Abstract: The article proposes and substantiates a method for studying the dynamics of an asynchronous electric drives with frequency control from the input side of the signal for setting the speed of rotation of the electric motor. In this method, a constant speed reference signal is added to a harmonic variable frequency signal. The set of amplitude changes and phase shifts of velocity oscillations are the initial data for identifying the dynamics of the studied control method. The logic of this method is determined by the previously obtained nonlinear transfer function of the link that forms the mechanical moment in the asynchronous electric drive with frequency control. Experiments have shown the dynamic benefits of the drive with positive stator current feedback.

Application of Matrix VFD for Power Factor Improvement in LED Lighting Sources Loaded Power Distribution Lines

Abstract: In this paper, a novel approach to matrix-converter-based variable frequency drives is presented. It is proposed that these drives are used to provide or draw out reactive power from the power distribution line, keeping the power factor close to unit and, simultaneously, performing their primary function of motor powering and speed control. This application of matrix-converter-based variable frequency drives is required due to the need to compensate for capacitive reactive power generated by light emitting diode lighting devices. In this study, the reactive power compensation range of the matrix-converter-based variable frequency drive is determined, and a method is proposed to extend the compensation range.

Technical and economic feasibility of using a variable-frequency drive in micro-irrigation systems

Abstract: Irrigation is essential for the development of crops in regions with scarcity or irregular rainfall distribution, enabling high productivity. However, the use of water resources and electrical energy leads to a concern with irrigation efficiency. Pressure demand varies during the operations of irrigation systems and the appropriate pressure can be regulated by variable-frequency drives for the power supply of the motor-pump set. This study aimed to analyze the technical and economic feasibility of using a variable-frequency drive to adjust the pressure in subunits of micro-irrigation systems. Laboratory tests were carried out to determine the electrical power consumed in each irrigated subunit for different slopes and the application or not of the variable-frequency drive. Thus, an economic analysis was carried out considering the electricity tariff for group B and rural consumer class, as well as different annual irrigation times. The results showed the potential for energy saving with the use of the variable-frequency drive. Thus, the economic analysis showed that the variable-frequency drive was a better alternative than the dissipative method.

Качество электрической энергии в системах электроснабжения горно-перерабатывающих предприятий россии

Abstract: This paper investigates the effect of the load factor of frequency converters and thyristor converters on electrical power quality. Recommendations for reducing the influence of higher harmonics and switching overvoltages on the characteristics of electrical power are provided. Higher harmonics were measured by a PKK57 complex device for controlling electrical parameters and a digital oscilloscope of the Tektronix TDS 2024V type. Impulse switching overvoltages were recorded by an active resistance divider of the DNEK-10 type and the above-mentioned oscilloscope. The obtained data were processed by the Loginom 6.4 software and the methods of mathematical statistics. The lower threshold level of the load factor of frequency converters and thyristor converters was set equal to 0.8, at which the sinusoidal distortion of voltage curves correspond to the RF standard of electrical power quality. The suppression degree of higher harmonics from the 5th to 17th frequency by power transformers with a capacity of 250–6,300 kV. A ranged from 95 to 45%. The use of the ‘transformer–converter–electric receiver’ system as applied to the power supply systems of mining and processing enterprises was substantiated. It was shown that electric motors with a capacity of up to 2,500 kW inclusively require protection against switching overvoltages. Conventional RC-absorbers based on RC-circuits connected to the terminals of electric motors are shown to be highly efficient for protecting electric motors against switching overvoltages. Thus, the quality of electrical power in power supply systems of mining and processing enterprises in Russia can be ensured by frequency converters and thyristor converters with a load factor of 0.8 or greater. Provided that the transformer capacity does not exceed 1,000 kV. A, a more efficient and less expensive ‘transformer–converter–electrical receiver’ system is recommended. Effective protection of electric motors of up to 2,500 kW inclusive can be provided using the proposed conventional RC absorber, which maintains the overvoltage rate at a level not exceeding 1.7.

Optimal Selection of Asynchronous Motor-Gearhead Couple Fed by VFD for Electrified Vehicle Propulsion

Abstract: Widespread applications of AC motors fed by variable frequency drives in electrified vehicles have become a conventional technical solution. The flexibility of control, low cost, and high energy efficiency attract developers and engineers to apply these appliances in cars, railway trains, trams, etc. The distinctive characteristic of vehicles is a wide range of required rotation speed and torque. This circumstance means that the problems of the AC motor (nominal power, synchronous speed) and gearbox (transmission ratio) become non-trivial and necessitate optimal selection to ensure the best functionality of the entire driving system. This study proposes an approach for the optimal choice of a specific AC motor (nominal rating, synchronous speed) and the transmission ratio of the gearbox by analyzing the entire system’s losses. The optimal selection of an AC motor ensures maximum energy efficiency for a specific transportation driving cycle.

Performance Analysis of Frequency Variation System using Drives (VT240s and Axpert Eazy) for Industrial Application

Abstract: The proposed research work describes the general system management and real-time applicability of VFD i.e. Variable frequency drive. The project embodies the automation of 2 styles of VFD series namely VT240S and Axpert eazy. These VFD are going to be managed through PLC. Further, VFD is employed for control. The speed of the motor is often serially and domestically managed by VFD. In domestic management, there will be a switch affiliation within the drive and in serial management, the motor is managed through PLC. The motor will stop by each ways. For serial management, the programs should style in software package and it will be downloaded in PLC and by giving external wire affiliation like Modbus 485 from PLC to VFD, the operation is completed. Recently, the speed of the motor control is emerging as a big issue in industrial automation. Machine control with accurate result is required in industry applications for the design and development of the tools in various domains. Machine speed is used to control and vary the frequency parameter. So, the Variable Frequency Drive [VFD] that has been used to control the speed of the motor by varying the range of frequency is proposed to design a VFD machine system with number of tools and machine learning techniques in the paper.

Energy saving analysis of air fan motor in power plant boiler controlled by variable frequency drive

Abstract: A reporting of Energy Audit in 2018 by LEMTEK UI has reported that air fan system currently used in Power Plant of PLTU Tanjung Jati B Jepara is inefficient, energy efficiency in FDF is only 32% and PAF efficiency is 49.01%. Inefficiency of the air fan system is an impacted there are waste of electric energy amount of 13,352,929 KWh (13,35 GWh) a year with a financial loss of IDR 13,352,929,140. To overcome this condition, variable frequency drive (VFD) is installed which adjusted air flow as needed so that energy waste can be reduced. MATLAB simulation is proposed to analyze the VFD method. The result shows that by using VFD, 8,233,573.444 KWh (8.45 GWh) can be saved a year. Total cost benefits are IDR 8,233,573,444 as 32.1% of saving cost. Efficiency of FDF is 72.57 % and PAF is 66.84%.

Development of Inverter Duty Motor Bearings for Si and SiC-Based Variable Frequency Drive Applications Including Advanced 4D Finite Element Modeling

Abstract: Conventional high dv/dt pulse-width modulated (PWM) inverters generate common-mode voltages (CMVs) within the motor windings, which due to the electrostatic (capacitive) coupling between the rotor and the stator windings and frame, enable voltage to build up on the motor shaft. Motor shaft voltages exceeding the dielectric capability of the bearing grease result in bearing currents that in time can damage the bearing surfaces due to electric discharge machining (EDM). This bearing current phenomenon has been widely discussed in the literature for Si-based motor drives, and more recently has been shown by the authors to be exacerbated by the higher dv/dt found in SiC-based inverters. This paper presents the development of cost-effective inverter duty motor bearings for Si- and SiC-based applications, including advanced 4D finite element modeling and experimental validation, with the ability to demonstrate longevity under varying load conditions.

Flatness-Based Single Tank Water Level Control Under Actuator Constraint

Abstract: This paper addresses water level regulation in a single tank. The classical solution is to linearize the non-linear dynamic and regulate the water level with a classical PID controller. If the actuator's saturation, e.g., the pump, is taken into account, the PID controller should have the anti-windup mechanism. A normal PLC and SCADA system cannot solve radically the monitoring and control under the constraint problem. We propose a PC-based flat controller approach. The whole control system is written in Python which controls the variable frequency drive directly using Modbus RTU and permits to locally/remotely monitor the control system at the same time. Communication employs MQTT protocol to send operational data to a remote LAMP server. A prototype is built to verify the performance of our controller which used low-cost flow sensors and an Arduino-based signal conditioning circuit. Kalman filter is then used to enhance input and output measuring.

Real-time dc-link voltage control of 5-kW PMSG-based wind turbine generator through a test-rig

Abstract: In this work unlike the usual grid side converter, the machine side converter is considered to control the dc-link voltage of a permanent magnet synchronous generator-based wind turbine generator. For this purpose, a discrete real-time laboratory test-rig is prepared for real-time application of the system. In the real-time test-rig, 5-kVA permanent magnet synchronous servo motor is driven by Unidrive SP variable frequency drive to emulate a standalone wind energy conversion system; GUASCH converter as a machine side converter and for implementing the designed PI controllers using pole placement technique combined with a symmetrical optimum criterion for real-time control of the dc-link voltage transient changes, Texas instrument TMS320F28069 digital signal processor discrete real-time microcontroller control card in a GUASCH board are used. Moreover, a simulation model of the system is prepared in MATLAB Simulink user-defined function blocks considering the dynamic mathematical equations of every part in the system. Achieved simulation and real-time test-rig results show that the designed dc-link voltage control of the system works properly at different transient load changes connected to the standalone WTG and dc voltage reference value changes. Moreover, the simulation results are properly validated by the real-time test-rig results and the PI controller designed using pole placement technique combined with a symmetrical optimum criterion method was ideal.

Analysis of the implementation of three-phase Variable Frequency Drive on the prototype of a rice drying machine

Abstract: The prototype of the rice drying machine is a device used for rice dryers that are not weather dependent. The driver of this prototype rice drying machine uses ½ HP induction motor as its main mover. To be able to adjust the rotation of the induction motor using Variable Frequency Drive (VFD) brand LS iC5 with 1 HP power. The rotation needed to rotate the load can be done by changing the frequency and voltage so that the rotation speed of the induction motor can be adjusted as needed. From the testing of a no-load induction motor with a frequency adjustment range from 5 Hz to 13 Hz, the induction motor speed is 142.8 rpm (rotation per minute) to 375.3 rpm. The measured voltage is 76.5 V to 116.7 V and the measured current is 2.5 A to 1.6 A. From the results of the test of a no-load induction motor it can be concluded that the ratio of frequency to voltage is directly proportional while the ratio of frequency to current is inversely proportional. In testing induction motors with a frequency adjustment range from 5 Hz to 9 Hz, they produce the same conclusions as to the induction motor load testing. VFD is certainly appropriate to be used as a speed regulator as needed.

Design and Implementation of Constant Speed control System for the Induction motors Using Programmable logic Controller (PLC) and Variable Frequency Derive (VFD)

Abstract: This paper presents an automatic speed control system on three phase squirrel cage induction motor using Programming Logic Circuit (PLC) and Variable Frequency Drive (VFD) techniques. The aim of this study is to obtain a constant speed of induction motors when these motors are exposed to variable loads. The required speed of the induction motor can be set as a numerical value by (PLC), while the actual speed of the induction motor can be measured by a tachometer which is equipped with (PLC) ) Through an Analog to Digital Converter (ADC). Then the two speeds are compared to the set point with minimum error to get the required constant speed. The control system designed to be tested with two stator poles number (two and four poles) of induction motors. The results have cleared that in spite of doubled the load 11 and 8 times respectively, but the yield average shaft speeds are almost constant 2891.15 rpm and 1402.45 rpm respectively.

A Novel Z-Type Self-Balancing Modular Multilevel Converter for Flywheel Driving Applications

Abstract: With the development of flywheel technology, the speed and the voltage level of flywheel continue to increase. The Z-type self-balancing modular multilevel converter can have a wide frequency range at medium voltage and is suitable for flywheel driving application. However, the voltage and current characteristics of the flywheel and the variable frequency drive still affect capacitor voltage balance in each phase-leg. The new balance of capacitor voltage can be achieved by controlling the circulating current. This paper proposed a control algorithm of the novel Z-type self-balancing modular multilevel converter for flywheel driving applications. Simulation results are presented to validate the theoretical analysis.

Efficient and Economically Optimized Way to Limit Inrush Current in an Induction Motor Using Solid-State Devices

Abstract: The paper proposes the development of a solid-state-based soft starter. It is a device that protects the motor from sudden influxes of power by limiting the large inrush of current during startup by gradually ramping up the voltage to rated, hence, producing the gradual start. It is used in an application that requires speed and torque control only during startup. Compared to conventional DOL direct online starters in which inrush current is five to ten times the rated current, the paper presents the development and implementation of a technique that provides precise control over inrush current. The added feature of a smooth stop provides protection against hammering in submersible motors. It not only satisfies the existing needs but also takes up less space than variable frequency drive (VFD); hence, stand out distinctively from the rest of its type thus making itself quite marketable. To make the solution economically viable and less complex, a fully analog-based circuit has been presented which significantly reduces the cost compared to microcontroller-based circuits.

A Hardware Framework for Three-Phase Converter Physical Modeling

Abstract: A low-cost voltage source inverter (VSI) module for building a laboratory testbed for experimental research works with 3-phase 3-wire networks with line-to-line voltage up to 250 VAC is presented. The module consists of a 3-phase 600 V 10 A IGBT bridge controlled by a 32-bit ARM microcontroller. The module also contains 2 galvanically-isolated UART communication ports; 4 current measurement channels and 5 voltage measurement channels. The module functionality is sufficient to perform experiments with many VSI applications, such as: variable frequency drive (VFD); regulated AC/DC voltage source; 1-phase voltage regulator; active rectifier; 1-phase grid-tie inverter; parallel or series active power filter etc. Furthermore, by combining two modules, it becomes possible to implement electronic load with variable parameters; four-quadrant VFD; unified power quality conditioner etc. The onboard communication ports allow to implement data exchange either between modules and/or between module and PC for data processing and storage. The usage of such VSI modules in educational purposes will allow to implement many laboratory experiments in the fields of electric drive, power converters, electric power quality, etc.

Analysis of VFD Induction Motor Current Disturbances by Prony Analysis and Motor Redesign by Intelligent Optimization Techniques

Abstract: An analytical approach is discussed in this paper to minimize the influence of disruptive current spikes occurring at low frequency in a Variable Frequency Drive (VFD) induction motor. In a continuous process industry a 3-phase, 550 kW, induction motor coupled with a reciprocating pump, is tested at low frequency. Prony method is used to analyze the data. The optimal values of motor design parameters that deliver sufficient mechanical power at low frequency and cause the least disruptive current spikes is arrived at, by using intelligent optimization techniques like Artificial Bee Colony (ABC), Particle Swarm Optimization (PSO), and Genetic Algorithm (GA). Using the optimal design values obtained, Taguchi method is applied on the VFD control parameters. The optimal control parameters thus obtained for tuning the VFD to get the minimal current spikes is comparable with the practical VFD parameters which is seen to be able to deliver stable operation of the motor at low frequency. The optimal motor design parameters can be used to procure a new motor that can give stable operation at low frequency.