1,721,054 research outputs found
Development of an Automatic Parameter Identification Method for PMSM Drives with an LC-Filter
No full textI dette projekt fokuseres der på, at udvikle en metode til parameter identifikation af etsystem med en inverter der styrer en elektrisk motor, hvor der er monteret et LC-filtermellem inverter og motor. En inverter styrer en motor ved pulsbreddemodulation,hvilket grundlæggende fremkommer af, at en række kontakter, mellem en DC forsyn-ing og motoren, slukker og tænder systematisk. I systemer der styres med pulsbred-demodulation, kan der opstå høje spændingsgradienter, hvilket kan føre til uønskedeegenskaber. Eksemplerpåuønskedeegenskabererakustiskstøjogbeskadigelseafmo-toren. For at reducere de uønskede egenskaber, implementeres et LC-filter melleminverter og motor. Normalvis estimeres et systems parametre for effektivt at kunnestyremotoren,mennåretLC-filterimplementeresisystemetsåøgeskompleksitetenafsystemet, hvorved identificering af systemets parametre ikke kan ske ved traditionellemetoder. Der ønskes derfor at udvikle en metode til parameteridentifikation, der kantilsluttes et eksisterende system med LC-filter og derved identifiere systemets parame-ter.Et testsystem har været opstillet i laboratoriet i forbindelse med projektet, beståendeaf inverter, LC-filter og motor. Systemets komponenter er undersøgt og modeller afsystemet er opstillet til simulering på PC. Det simulerede system benyttes til udviklingaf en metode til parameter identifikation af systemet, som eftervises på laboratorieop-stillingen.Der udvikles en metode til parameteridentifikation, inspireret af artikler på området.Metoden til parameteridentifikation tager udgangspunkt i at excitere systemet med etpulsbreddemoduleret signal, der er baseret på en tilfældig sekvens af binære tal. Sys-temetsspændinger ogstrømme måles, medegetudviklethardware, ogbruges til, ates-timere systemet udfra spektralanalyse. Et analytisk udtryk for systemet opstilles og enoptimeringsalgoritme benyttes til, at tilpasse det analytiske udtryk til det estimeredesystem, hvorved systemets parametre identificeres.I forbindelse med excitering og måling af systemet, har der været udviklet og fremstil-let hardware specifikt til formålet. Ved design af hardware har der været fokus på præ-cise målinger med høj båndbredde, samt frasortering af støjgradienter. Det designedehardware har været fremstillet i laboratoriet, på Aalborg Universitet, og er fremstillet afprojektdeltagerne.Metoden til parameteridentifikation afprøves på det simulerede system, hvor meto-denspræstationevalueres,førmetodenimplementerespålaboratorieopstillingen. Vedimplementering i laboratoriet benyttes det egetudviklede hardware, sammen med enindlejret enhed fra National Instruments, til afvikling af det tilhørende software. Dettilhørende software er udviklet til, at kunne fungere, som en stand alone løsning, hvorprogrammet kan initialiseres og resultater aflæses uden brug af eksternt udstyr.Afslutningsvis undersøges der, hvilke indstillinger af metoden der medfører en effektivog præcis identifikation af laboratorieopstillings parametre. Der undersøges hvilkenindflydelse forskellige indstillinger har på eksekveringstid og resultat af optimeringsal-goritmen.Thisprojectaimstoovercomethediffi-culties of determining the parameters ofa drive system with an inverter, an LC-filter and a motor.A laboratory setup is established withaninverter,anLC-filterandapermanentmagnetsynchronousmotor. Thelabora-tory setup is investigated and computermodels are developed for simulation.An automatic parameter identificationmethod is designed for a stand alonesolution. The method contains systemexcitation with pulse width modulation,based on a sequence of random binarynumbers, frequency response estima-tionfromspectralanalysis,andcurvefit-ting with an optimization algorithm.Customhardwareisdesignforthepur-pose of this project. The hardware isdesigned for control of an inverter andsampling of signals where high preci-sion, high bandwidth, and noise mitiga-tion is key. The designed hardware ismanufactured in the laboratory.The parameter identification methodis tested with the simulated system toevaluate the method’s performance. Fi-nally the method is used to determinethe parameters of the laboratory setup.The parameter identification methodis concluded successful in identifyingthe parameters of the laboratory setup
Control of LC-filter connected PMSM using Internal State Estimator
No full textThe purpose of this project is to analyze the influence of connecting an LC-filter to a drive system and investigate whether it is possible to use simpler control designs to stabilize the system as an alternative to the standard 4-level cascade control. By applying the Field Oriented Control (FOC) method three control design options are presented and it is investigated if the simpler Option 2 is viable as control of the LC-filter connected drive system. In order to stabilize the control system as a result of the produced resonance from the connected LC-filter an Full-Order-Observer is needed to estimate the non-measured stator currents and filter out the resonance. The Full-Order-Observer design method is introduced with the partially purpose to estimate the internal states based on the measured inverter currents. To verify these methods the control systems are implemented in a dSPACE laboratory setup running a DSP platform with MATLAB/Simulink interface. Various scenarios producing experimental data is then tested throughout the chapters for ongoing validation
Prediction of electricity consumption of heat pumps for use in an intelligent power-grid
No full textThe Danish power-grid has to include more renewable energy. By 2050 the consumptionhas to be 100 % based on renewable energy. This means more wind-power, and otherintermittent power producers will be incorporated in the grid. Since the energy-producersare not well-suited to change their production, the demand-side has to be more flexible inthe future.One way of making the demand more flexible is by gathering electricity consumers in aVirtual Power Plant (VPP) and control when they are using power and not. This study isfocused on predicting the power of a VPP consisting of a pool of heat pumps.A model has been developed, together with methods for estimating the parameters forthe model, and an approach to evaluating the performance of the model. The model takesdata from the “Control Your Heat Pump” platform to make the parameter-estimation. Thereport demonstrates how this model is deployed by using Matlab and YALMIP.The Danish power-grid has to include more renewable energy. By 2050 the consumptionhas to be 100 % based on renewable energy. This means more wind-power, and otherintermittent power producers will be incorporated in the grid. Since the energy-producersare not well-suited to change their production, the demand-side has to be more flexible inthe future.One way of making the demand more flexible is by gathering electricity consumers in aVirtual Power Plant (VPP) and control when they are using power and not. This study isfocused on predicting the power of a VPP consisting of a pool of heat pumps.A model has been developed, together with methods for estimating the parameters forthe model, and an approach to evaluating the performance of the model. The model takesdata from the “Control Your Heat Pump” platform to make the parameter-estimation. Thereport demonstrates how this model is deployed by using Matlab and YALMIP
Modelling, Optimisation, and Design of Fast Switching Solenoid Valve
No full textThe transmission of large scale wind turbines has traditionally been done mechanically but the development of larger turbines has been pushing this solution to its limits and the hydrostatic transmission is candidating its dominance. However, the hydrostatic transmission has its disadvantages in that traditional hydraulic pumps and motors are inefficient at small displacements and further development is therefore needed. Digital Displacement Technology could be the improvement needed for feasibility and has been investigated by industry and academia alike. Studies have shown that a low pressure drop and fast switching valves are necessary for the success of this technology. This thesis investigates the modelling, optimisation, and design of such valve. The valve topology of interest is the variable reluctance or solenoid valve which history has proven reliable but suffering from a poor transient response compared to newer topologies. This disadvantage is sought minimised.The study showed showed that in order to achieve the low pressure drop necessary the travel distance must also increase causing the switching time to increase thereby yielding an inefficient design
Electromagnetic Finite Element Analysis and Simulation-Based Design Optimisation of Busbar
No full textIn MW-size converters used for offshore wind turbines, more than a tonne of copper is used forthe conduction of electricity. The busbars used for this purpose are often simple, solid geometries.The skin and proximity effect, which are inductive effects from AC current, cause the current toflow near the surface of the conductor, meaning that the cross sections are poorly utilised.A three-dimensional copper busbar is redesigned with the intention of reducing the overall volumeof the part while keeping a minimal increase in Joule losses. The current waveforms which thebusbar is subject to are analysed and simulated in PLECS, as the power module switchingfrequency significantly affects the waveform. The frequencies that cause the highest Joule lossesare selected and verified to have the same RMS components in the time and frequency domain.These frequency components are used as input in quasi-static electromagnetic Finite ElementMethod simulations using COMSOL Multiphysics. This model solves Maxwell’s equations,including the inductive effects for the given frequencies and currents.A transient model using the same physics interface is compared and verified with a pulse test ofthe reference busbar with cutouts in the geometry allowing the measurement of current runningin different parallel paths of the busbar using Rogowski coils, to investigate the propagation ofthe current through the material over time.The model is used in a design space exploration where the busbar is swept through variousqualitatively selected partial changes in topology of the busbar, with the aim of finding acompromise solution between increases in Joule losses and mass reduction. The Joule lossesare dependent upon current and AC resistance, which becomes difficult to estimate for nontrivial 3D structures. The explicit results from COMSOL are therefore used to assess an objectivefunction, which evaluates the reduction of mass, Joule losses, and surface area. Since temperaturedevelopment is a function of Joule losses and surface area, a loss-area ratio is set up, as moresurface area will mitigate excessive heating from Joule losses since the busbar is subject to forcedcooling.The design which best satisfies the objective function is extrapolated to the entire busbargeometry. To compare the thermal performance of this extrapolated design to the referencebusbar, as well as the non-linear temperature-dependent resistance of copper, a heat transfermodel is developed. This combines an electromagnetic model for Joule losses, a heat transfermodel for temperature development, and a computational fluid dynamics model for modellingairflow and convection. The final design achieves a large improvement in mass and surface area,albeit with an increase in Joule losses mainly due to increased AC resistance. However, the heattransfer model shows that this new design converges at a lower temperature than the referencebusbar, because of the increase in surface area
Control and Parameter Identification of a Permanent Magnet Synchronous Motor with a LC-filter
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