Sensorless control strategy for light-duty EVs and efficiency loss evaluation of high frequency injection under standardized urban driving cycles

Sensorless control of Electric Vehicle (EV) drives is considered to be an effective approach to improve system reliability and to reduce component costs. In this paper, relevant aspects relating to the sensorless operation of EVs are reported. As an initial contribution, a hybrid sensorless control algorithm is presented that is suitable for a variety of synchronous machines. The proposed method is simple to implement and its relatively low computational cost is a desirable feature for automotive microprocessors with limited computational capabilities. An experimental validation of the proposal is performed on a full-scale automotive grade platform housing a 51¿kW Permanent Magnet assisted Synchronous Reluctance Machine (PM-assisted SynRM). Due to the operational requirements of EVs, both the strategy presented in this paper and other hybrid sensorless control strategies rely on High Frequency Injection (HFI) techniques, to determine the rotor position at standstill and at low speeds. The introduction of additional high frequency perturbations increases the power losses, thereby reducing the overall efficiency of the drive. Hence, a second contribution of this work is a simulation platform for the characterization of power losses in both synchronous machines and a Voltage Source Inverters (VSI). Finally, as a third contribution and considering the central concerns of efficiency and autonomy in EV applications, the impact of power losses are analyzed. The operational requirements of High Frequency Injection (HFI) are experimentally obtained and, using state-of-the-art digital simulation, a detailed loss analysis is performed during real automotive driving cycles. Based on the results, practical considerations are presented in the conclusions relating to EV sensorless control.Peer ReviewedPostprint (published version

Sensorless position estimation in fault-tolerant permanent magnet AC motor drives with redundancy.

Safety critical applications are heavily dependent on fault-tolerant motor drives being capable of continuing to operate satisfactorily under faults. This research utilizes a fault-tolerant PMAC motor drive with redundancy involving dual drives to provide parallel redundancy where each drive has electrically, magnetically, thermally and physically independent phases to improve its fault-tolerant capabilities. PMAC motor drives can offer high power and torque densities which are essential in high performance applications, for example, more-electric airplanes. In this thesis, two sensorless algorithms are proposed to estimate the rotor position in a fault-tolerant three-phase surface-mounted sinusoidal PMAC motor drive with redundancy under normal and faulted operating conditions. The key aims are to improve the reliability by eliminating the use of a position sensor which is one of major sources of failures, as well as by offering fault-tolerant position estimation. The algorithms utilize measurements of the winding currents and phase voltages, to compute flux linkage increments without integration, hence producing the predicted position values. Estimation errors due measurements are compensated for by a modified phase-locked loop technique which forces the predicted positions to track the flux linkage increments, finally generating the rotor position estimate. The fault-tolerant three-phase sensorless position estimation method utilizes the measured data from the three phase windings in each drive, consequently obtaining a total of two position estimates. However, the fault-tolerant two-phase sensorless position estimation method uses measurements from pairs of phases and produces three position estimates for each drive. Therefore, six position estimates are available in the dual drive system. In normal operation, all of these position estimates can be averaged to achieve a final rotor angle estimate in both schemes. Under faulted operating conditions, on the other hand, a final position estimate should be achieved by averaging position estimates obtained with measurements from healthy phases since unacceptable estimation errors can be created by making use of measured values from phases with failures. In order to validate the effectiveness of the proposed fault-tolerant sensorless position estimation schemes, the algorithms were tested using both simulated data and offline measured data from an experimental fault-tolerant PMAC motor drive system. In the healthy condition, both techniques presented good performance with acceptable accuracies under low and high steady-state speeds, starting from standstill and step load changes. In addition, they had robustness against parameter variations and measurement errors, as well as the ability to recover quickly from large incorrect initial position information. Under faulted operating conditions such as sensor failures, however, the two-phase sensorless method was more reliable than the threephase sensorless method since it could operate even with a faulty phase.Thesis (Ph.D.) -- University of Adelaide, School of Electrical and Electronic Engineering, 201

Position/speed sensor-less control of wind energy conversion systems based on Rotor-Tied Doubly-Fed induction generator systems

Thesis (PhD)--Stellenbosch University, 2019.ENGLISH ABSTRACT: The doubly-fed induction generator (DFIG) is amongst the most popular wind turbine generator in South Africa. This is partly due to the fact that its backtoback power converters are partially rated. More precisely, they are rated at 30% of the generator rated power. A new DFIG topology has been proposed recently. That is the rotor-tied doubly-fed induction generator (RDFIG). In this topology, the rotor side is connected to the grid while the stator side is connected to the power converter. It has been shown that this topology holds the advantage of higher effeciency compared to the standard DFIG topology. High accuracy in all the measurements is required for the optimum operations of wind energy conversion systems (WECSs). The measurement of the rotor position/speed is amongst the most important measurements when it comes to implement any control system for the WECS. The conventional method of measuring the rotor position/speed is to use an electronic/mechanical sensor (encoder or resolver). This measurement involves the use of long cables and in a harsh environment, this can lead to faulty operations of the WECS. In this thesis, several slip speed estimators for sensor-less control of RDFIGbased WECSs are developed and implemented. The proposed slip speed estimators are based on the association of different sliding mode observers and the PLL estimator. The association of the PLL estimator improves the estimation performance by reducing the noise created by the sliding control control functions. Also, the proposed PLL estimator helps in avoiding a phase shift of π in super-synchronous operating conditions. In addition, in this thesis, several sliding mode observers were developed in order to improve the estimation performance. The proposed sliding mode observers were satisfactory for all the operating conditions of the RDFIG-based WECSs. The robustness of the proposed slip speed estimators is validated experimentally under various operating conditions. A 5.5-kW custom-designed gridconnected RDFIG test-bench based on a National Instrument (NI) PXIe-8115 controller is used. The proposed slip speed estimators solve the problem linked to the failure of the electromechanical sensors. The overall sensor-less control strategy provides an alternative to the sensor-based control of the RDFIGs. Also, the proposed sensor-less vector control strategy can be used as a back-up in case the electromechanical sensor fails.AFRIKAANSE OPSOMMING: Die dubbelgevoerde induksiegenerator (DFIG) is een van die gewildste windturbinegenerators in Suid-Afrika. Dit is deels as gevolg van die laer kapasiteit omsetters wat die DFIG benodig. 'n Nuwe DFIG-topologie is onlangs voorgestel: Die rotorgebonde DFIG (RDFIG). In dié topologie word die masjien se rotor aan die netwerk gekoppel en die stator aan laer kapasiteit omsetters. Dit is bewys dat hierdie topologie 'n hoër masjieneffektiwiteit het in vergelyking met die standaard-DFIG. Hoë akkuraatheid van metings word vereis vir die optimale beheer van windenergie-omsettingstelsels (WECS). Die meting van die rotorposisie en - spoed is van die belangrikste metings wanneer dit kom by die beheerstelsel van 'n WECS. Die konvensionele metode van rotorposisie- en rotorspoedmeting is deur middel van 'n kodeerder. Dié meting behels die gebruik van lang kabels in 'n fel omgewing, wat kan lei tot die foutiewe werking van die stelsel. In hierdie verhandeling word verskeie glipspoedafskatters vir die sensorlose beheer van 'n RDFIG-gebaseerde WECS ontwikkel en geïmplimenteer. Die voorgestelde glipspoedafskatter is gebaseer op die assosiasie van verskillende glymodus-observeerders en 'n PLL-afskatter. Die assosiasie van die PPLafskatter verbeter die afskattingprestasie deur die geruis van die glymodusbeheerstelsels te verminder. Die voorgestelde PPL-afskatter help ook om 'n faseskuif van π te vermy tydens super-sinchroonoperasie. In hierdie verhandeling word verskeie glymodusobserveerders ontwikkel om die afskattingsprestasie te verbeter. Die voorgestelde glymode-observeerders presteer bevredigend vir alle toestande van die RDFIC-gebaseerde WECS. Die kragtigheid van die voorgestelde glipspoedafskatters se geldigheid word onder verskeie toestande eksperimenteel getoets en bewys. 'n 5.5 kW netwerkgekoppelde RDFIG toetsbank gebaseer op 'n National Instrument PXIe-8115-beheerder word gebruik. Die probleem van gefaalde elektromeganiese sensors word deur die voorgestelde glipspoedafskatters opgelos. Die sensorlose beheerstrategie gee ook 'n alternatief vir tradisionele sensor-gebaseerde beheer van die RDFIG's.Master

Full- & Reduced-Order State-Space Modeling of Wind Turbine Systems with Permanent-Magnet Synchronous Generator

Wind energy is an integral part of nowadays energy supply and one of the fastest growing sources of electricity in the world today. Accurate models for wind energy conversion systems (WECSs) are of key interest for the analysis and control design of present and future energy systems. Existing control-oriented WECSs models are subject to unstructured simplifications, which have not been discussed in literature so far. Thus, this technical note presents are thorough derivation of a physical state-space model for permanent magnet synchronous generator WECSs. The physical model considers all dynamic effects that significantly influence the system's power output, including the switching of the power electronics. Alternatively, the model is formulated in the $(a,b,c)$- and $(d,q)$-reference frame. Secondly, a complete control and operation management system for the wind regimes II and III and the transition between the regimes is presented. The control takes practical effects such as input saturation and integral windup into account. Thirdly, by a structured model reduction procedure, two state-space models of WECS with reduced complexity are derived: a non-switching model and a non-switching reduced-order model. The validity of the models is illustrated and compared through a numerical simulation study.Comment: 23 pages, 11 figure

Traction control in electric vehicles

Tese de Mestrado Integrado. Engenharia Electrotécnica e de Computadores. Área de Especialização de Automação. Faculdade de Engenharia. Universidade do Porto. 201

Accurate angle representation from misplaced hall-effect switch sensors for low-cost electric vehicle applications

© 2022 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting /republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksThis article presents an accurate method to determine the mandatory rotor position to control a permanent magnet synchronous machine from misplaced Hall-effect switch sensors. The main feature of this technique is the estimated speed from two consecutive edge transitions in the same phase to dodge the inaccurate information. Besides, when a new electrical cycle starts, a gradual compensation algorithm corrects the initial speed estimation to cancel the electrical angle error in order to prevent current distortions. Furthermore, a first-order Taylor series approximation estimates the rotor position from the compensated speed calculation, reducing the possible torque ripple and noise due to an inaccurate control strategy. The proposed method has been compared with other state-of-the-art approaches through simulation and experimental results obtained from a low-voltage powertrain, showing more straightforward implementation and delivering the best balance performance during steady-state and transient operation.Peer ReviewedPostprint (author's final draft

Metoda za estimaciju magnetskog toka rotora kaveznih asinkronih generatora bez mjernog člana brzine vrtnje temeljena na fazno spregnutoj petlji

This paper presents a new rotor flux estimation method for sensorless vector controlled squirrel-cage inductiongenerators used in wind power applications. The proposed method is based on a phase-locked loop (PLL) and theorthogonality between the rotor flux space vector and its back electromotive force (EMF) space vector. Rotor flux isestimated using stator voltage equations without integrating the back EMF components in the stationary referenceframe and the well-known difficulties with the implementation of pure integrators are thus avoided. Moreover, theproposed method ensures successful magnetization of a speed-sensorless squirrel-cage induction generator at nonzerospeeds which makes it suitable for wind power applications. Experimental results on a 560 kW squirrel-cageinduction generator are presented to confirm the effectiveness and the feasibility of the proposed method.U radu je predstavljena nova metoda za estimaciju magnetskog toka rotora vektorski upravljanih kaveznih asinkronih vjetrogeneratora. Predložena metoda se temelji na fazno spregnutoj petlji i ortogonalnosti između prostornog vektora magnetskog toka rotora i njemu pripadajućeg prostornog vektora induciranog napona. Magnetski tok rotora se estimira korištenjem naponskih jednadžbi statora u koordinatnom sustavu statora bez integracije komponenti induciranog napona čime su izbjegnuti dobro poznati problemi implementacije integratora. Osim toga, predložena metoda omogućava uspješno magnetiziranje pri vrtnji kaveznog asinkronog generatora bez mjernog člana brzine vrtnje pa je pogodna za primjenu na vjetrogeneratorima. U radu su prikazani eksperimentalni rezultati za kavezni asinkroni generator snage 560~kW koji potvrđuju izvedivost i učinkovitost predložene metode

Field weakening and sensorless control solutions for synchronous machines applied to electric vehicles.

184 p.La polución es uno de los mayores problemas en los países industrializados. Por ello, la electrificación del transporte por carretera está en pleno auge, favoreciendo la investigación y el desarrollo industrial. El desarrollo de sistemas de propulsión eficientes, fiables, compactos y económicos juega un papel fundamental para la introducción del vehículo eléctrico en el mercado.Las máquinas síncronas de imanes permanentes son, a día de hoy la tecnología más empleada en vehículos eléctricos e híbridos por sus características. Sin embargo, al depender del uso de tierras raras, se están investigando alternativas a este tipo de máquina, tales como las máquinas de reluctancia síncrona asistidas por imanes. Para este tipo de máquinas síncronas es necesario desarrollar estrategias de control eficientes y robustas. Las desviaciones de parámetros son comunes en estas máquinas debido a la saturación magnética y a otra serie de factores, tales como tolerancias de fabricación, dependencias en función de la temperatura de operación o envejecimiento. Las técnicas de control convencionales, especialmente las estrategias de debilitamiento de campo dependen, en general, del conocimiento previo de dichos parámetros. Si no son lo suficientemente robustos, pueden producir problemas de control en las regiones de debilitamiento de campo y debilitamiento de campo profundo. En este sentido, esta tesis presenta dos nuevas estrategias de control de debilitamiento de campo híbridas basadas en LUTs y reguladores VCT.Por otro lado, otro requisito indispensable para la industria de la automoción es la detección de faltas y la tolerancia a fallos. En este sentido, se presenta una nueva estrategia de control sensorless basada en una estructura PLL/HFI híbrida que permite al vehículo continuar operando de forma pseudo-óptima ante roturas en el sensor de posición y velocidad de la máquina eléctrica. En esta tesis, ambas propuestas se validan experimentalmente en un sistema de propulsión real para vehículo eléctrico que cuenta con una máquina de reluctancia síncrona asistidas por imanes de 51 kW