Fault Detection of a Sensorless Controlled Electric Drive Using Load Torque Observer

The paper presents the problem of monitoring and fault detection of a drive torque transmission system which consists of an inverter supplied squirrel cage induction motor. The detection is based on the analysis of the estimated induction motor load torque, which operates in a sensorless control. The load torque is estimated as an additional value between other control values: rotor speed and rotor flux (this values are also estimated). The drive system is only equipped with standard sensors used in inverters. The investigations were done with a laboratory system that consists of the investigated machine and a controlled load (induction generator). An accurate control of the machine and programmed fast generator torque changes make it possible to simulate different types of faults in the drive torque transmission system. The possible simulated drive faults are e.g. rotor unbalances, eccentricities, etc. Moreover, the drive system with observer was expanded with a fault detection procedure. The paper presents the theoretical backgrounds, the drive system structure and the state observer. Results of experimental investigations are included for a 5.5kW drive system.W artykule przedstawiono metodę monitorowania oraz detekcji uszkodzeń układu transmisji momentu w przekształtnikowym napędzie elektrycznym. Detekcję uszkodzeń oparto na analizie estymowanego momentu obciążenia silnika indukcyjnego pracującego w bezczujnikowym układzie sterowania. Moment obciążenia estymowany jest jako dodatkowa wielkość oprócz innych sygnałów wykorzystywanych przy sterowaniu, tj.: prędkości obrotowej i strumienia wirnika (te wielkości są również estymowane). Układ napędowy wyposażony jest jedynie w czujniki standardowo stosowane w falownikach. Badania zrealizowano w układzie laboratoryjnym składającym się z maszyny badanej i regulowanego obciążenia (generatora indukcyjnego). Przez odpowiednie sterowanie maszyny obciążającej uzyskano możliwość modelowania różnych uszkodzeń układu transmisji momentu elektromagnetycznego. Umożliwia to sztuczne wprowadzanie do układu eksperymentalnego różnych rodzajów uszkodzeń, np. niewyważenia wirnika, nieosiowości, itp. Układ napędowy z obserwatorem momentu wyposażony został w procedurę identyfikacji uszkodzeń. W artykule przedstawiono zależności teoretyczne, strukturę układu napędowego oraz obserwatora stanu. Zamieszczono wyniki badań eksperymentalnych dla napędu elektrycznego 5.5 kW

Evolutionary algorithms in gains selection of extended speed observer of induction machine

W pracy opisano sposób doboru wzmocnień rozszerzonego obserwatora prędkości maszyny indukcyjnej przy wykorzystaniu algorytmów ewolucyjnych. Zaproponowano funkcję celu opartą na rozkładzie biegunów obserwatora. Ze względu na wpływ prędkości maszyny na dynamikę obserwatora zaproponowano dobór wzmocnień obserwatora dla różnych przedziałów prędkości. Dla poszczególnych przedziałów zaprezentowano wyniki doboru wzmocnień w postaci tabel prezentujących wartości funkcji celu w ostatnim pokoleniu algorytmu ewolucyjnego w kolejnych próbach doboru wzmocnień.The paper concerns the problem of gains selection of extended speed observer for induction machines. Equations of the observer as well as equations of the dynamics of estimation errors have been presented. Dynamic properties and stability of the observer depend on proper gains selection. The analyzed observer requires an adjustment of 12 gains. Furthermore, the complexity of linearized equations of the error estimation dynamics makes an analytical solution approach for the problem of gains selection impossible. A method based on evolutionary algorithm has been proposed in order to counteract this problem, where a cost function based on poles placement of the observer has been presented. Defined cost function ensures stability of the observer as well as good dynamic properties. The main goal is a transient time reduction of the observer which ensures a proper damping properties in order to avoid the presence of estimation errors oscillations during transient states. Three different rotor speed ranges are considered with separate observer gains set. A series of gains selection attempts have been conducted for every presented speed range. The final results presents and discusses the cost function values in the last generation of evolutionary algorithm

Morphology and the physical and thermal properties of thermoplastic polyurethane reinforced with thermally reduced graphene oxide

In this study, thermally reduced graphene oxide (TRG)-containing polyurethane nanocomposites were obtained by the extrusion method. The content of TRG incorporated into polyurethane elastomer systems equaled 0.5, 1.0, 2.0 and 3.0 wt%. The morphology, static and dynamic mechanical properties, and thermal stability of the modified materials were investigated. The application of TRG resulted in a visible increase in material stiffness as confirmed by the measurements of complex compression modulus (E′) and glass transition temperature (Tg). The Tg increased with increasing content of nanofiller in the thermoplastic system. The addition of thermally reduced graphene oxide had a slight effect on thermal stability of the obtained materials. The incorporation of 0.5, 1.0, 2.0 and 3.0 wt% of TRG into a system resulted in increased char residues compared to unmodified PU elastomer. Also, this study demonstrated that after exceeding a specific amount of TRG, the physicomechanical properties of modified materials start to deteriorate

Sensorless field oriented control for five-phase induction motors with third harmonic injection and fault insensitive feature

The paper presents a solution for sensorless field oriented control (FOC) system for five-phase induction motors with improved rotor flux pattern. In order to obtain the advantages of a third harmonic injection with a quasi-trapezoidal flux shape, two vector models, α1–β1 and α3–β3, were transformed into d1– q1, d3– q3 rotating frames, which correlate to the 1st and 3rd harmonic plane respectively. A linearization approach of the dual machine model in d – q coordinate frames is proposed by introducing a new additional variable “x” which is proportional to the electromagnetic torque. By applying the static feedback control law, a dual mathematical model of the five-phase induction motor was linearized to synthesize a control system in which the electromagnetic torque and the rotor flux can be independently controlled. The results shows the air gap flux shape in steady as well transient states under various load conditions. Moreover, the implemented control structure acquires fault tolerant properties and leads to possible emergency running with limited operation capabilities. The fault-tolerant capability of the analyzed machine was guaranteed by a special implemented control system with a dedicated speed observer, which is insensitive to open-phase fault situation. The experimental tests have been performed with single and double-open stator phase fault. A torque measurement was implemented to present the mechanical characteristics under healthy and faulty conditions of the drive system

Sensorless low speed PMSM control with cogging torque compensation

W pracy przedstawiono propozycję rozwiązania problemu bezczujnikowego sterowania wolnoobrotową maszyną synchroniczną z magnesami trwałymi PMSM. Przedstawiono silnik PMSM, który zastosowano w stanowisku badawczym. Omówiono problem występowania tętnień momentu napędowego wynikający głównie ze znacznego momentu zaczepowego. Pokazano rozwiązanie kompensujące tętnienia momentu napędowego w silniku PMSM. Przygotowano procedurę startową układu regulacji prędkości pozwalającą na uruchomienie napędu bez czujników prędkości i położenia. Do sterowania silnikiem użyto metodę sterowania polowo zorientowanego z regulatorami PI prądów stojana w osiach dq. Przedstawiono zależności nowej, prostszej wersji obserwatora stanu. Pokazano wyniki eksperymentów potwierdzających poprawne działanie napędu.The paper presents a possible implementation of a sensorless low speed permanent magnet synchronous machine (PMSM) control. The test setup for this purpose consists of an individual and programmable back-to-back voltage inverter and a PMSM with nominal power of 12 kW and nominal speed of 600 rpm. The impact of cogging torque oscillations is identified, which cause significant problems in the implementation of a Field Oriented Control for low speed PMSM. In order to handle this torque oscillation problem a compensation method is proposed as well. A start-up procedure for the control system was implemented that allows a motor start without any rotor angle and speed sensors. The presented control method is based on the Field Oriented Control with PI stator current controllers in dq axes. Furthermore, the equations of the applied state observer are shown. The observer estimates all of the control variables necessary using phase current measurement and the information of the desired stator voltage. All theoretical assumptions are verified with experimental results, which show the proper operation of the low speed PMSM drive

Sensorless five-phase induction motor drive with third harmonic injection and inverter output filter

The paper presents a sensorless control approach for a five-phase induction motor drive with third harmonic injection and inverter output filter. In the case of the third harmonic injection being utilised in the control, the physical machine has to be divided into two virtual machines that are controlled separately and independently. The control system structure is presented in conjunction with speed and rotor flux observers that are required for a speed sensorless implementation of the drive. The last section is dedicated to experimental results of the drive system in sensorless operation, and the uninterrupted drive operation for two open-phase faults

Interrelated shape memory and Payne effect in polyurethane/graphene oxide nanocomposites

International audienc

Interrelated shape memory and Payne effect in polyurethane/graphene oxide nanocomposites

International audienc

Dielectric properties of modified graphene oxide filled polyurethane nanocomposites and its correlation with rheology

This study aims at investigating the dynamic mechanical, dielectric and rheological properties of reinforced polyurethane (PU) nanocomposites containing hydrophilic graphene oxide (GO) and/or hydrophobic modified graphene oxide (mGO) sheets. The organic modification of GO was performed with 4,4'-methylenebis (phenyl isocyanate) (MDI) and the samples were prepared by solvent mixing. We found that addition of mGO provides a more significant increase in the dielectric permittivity as compared to the addition of GO. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) spectroscopy demonstrate the more effective dispersion of thin exfoliated sheets of mGO in the PU matrix as compared to unmodified GO. This qualitative morphology observation is correlated with the quantitative results inferred from the dynamic mechanical analysis, rheology and dielectric studies. The viscoelastic Payne effect is noticed for all nanocomposites and the filler–filler and polymer–filler interactions are studied by applying the Kraus and Maier and Goritz models. The non-linear viscoelastic behavior of the PU nanocomposites is in good agreement with the Maier and Goritz model, which includes the effects of the adsorption/desorption of PU chains on the filler surface. The observed results underline the possibilities of PU composites with organically modified GO sheets in capacitor applications