Axial position estimation of conical shaped motors for aerospace traction applications

This paper is concerned with the use of conical induction machines. Such machines are extremely valuable when apart from the rotational torque output, an axial translation of the rotor is also required. The inherent attraction between the stator and rotor of any machine, combined with the geometry of a conical machine will provide the required axial movement. However, when applied to aerospace applications, where reliability is very important, then full monitoring of the axial position is required. In this paper, an innovative approach aimed at monitoring and controlling the axial translation of a conical induction machine is proposed and investigated. In order to increase the system reliability and also decrease component count, as demanded by the application, the methodology is a sensor-less technique, based on an innovative variant of the high-frequency injection approach. In this paper, the technique has been fully investigated and experimentally validated on a purposely-built, instrumented test-rig

Identification of the Induction Motor Parameters at Standstill Including the Magnetic Saturation Characteristics

Identification of the induction motor parameters at standstill is studied in this thesis. The main goal of this work is to search for the feasible and applicable speed sensorless self-commissioning schemes. The magnetic saturation of the magnetizing inductance is taken into account. The magnetizing inductance is modeled as a function of the stator flux. Two different identification schemes are chosen based on the literature review. First method uses the single-axis sinusoidal excitation as the test signal. Second method uses the DC-decay test for the magnetizing inductance estimation and DC-biased sinusoidal excitation for the leakage inductance and rotor resistance identification. The DC-decay test is found to be a suitable method for identification of the magnetizing inductance. The single-axis sinusoidal excitation is found to be problematic in the saturation region. The source of the inaccuracy in the single-axis sinusoidal excitation is studied and the reasons are explained. The sensitivity of the schemes to the stator resistance and stator voltage errors is evaluated. Both methods show a very high sensitivity to the stator voltage errors in the case of the magnetizing inductance estimation. However, the DC-decay test shows a lower estimation error in the presence of the stator resistance errors. The estimation of the leakage inductance is robust against the stator voltage errors when the method based on the single-axis sinusoidal excitation is used. The estimation of the rotor resistance using the DC-biased excitation depends on the DC offset current in the presence of both the stator resistance and stator voltage errors

High-frequency issues using rotating voltage injections intended for position self-sensing

The rotor position is required in many control schemes in electrical drives. Replacing position sensors by machine self-sensing estimators increases reliability and reduces cost. Solutions based on tracking magnetic anisotropies through the monitoring of the incremental inductance variations are efficient at low-speed and standstill operations. This inductance can be estimated by measuring the response to the injection of high-frequency signals. In general however, the selection of the optimal frequency is not addressed thoroughly. In this paper, we propose discrete-time operations based on a rotating voltage injection at frequencies up to one third of the sampling frequency used by the digital controller. The impact on the rotation-drive, the computational requirement, the robustness and the effect of the resistance on the position estimation are analyzed regarding the signal frequency

Онлайн-идентификация электромагнитных параметров асинхронного двигателя

Incompliance of the settings of the system to control actual values of the parameters of a variable frequency induction electric drive may sometimes result in complete non-operability of a variable frequency electric drive as well as in the considerable reduction of the dynamic quality parameters. Such parameters as active rotor resistance, rotor inductance, and inductance of the magnetization circuit are available for the immediate measuring. They are not identified in terms of the acceptance tests, and the values presented in catalogues and reference books are calculated ones that may differ considerably from the real values of a certain machine. Despite constant studies by the researchers, a task to identify electromagnetic parameters of the equivalent circuit of an induction motor is still important and topical. The objective of the paper is to develop a method of online-identification of the electromagnetic parameters of an induction motor making it possible to implement accurate regulator adjustment of the frequency control system in terms of operational changes in the driving motor parameters. For the first time, the paper analyzes a steady mode of induction motor operation which does not apply T-network of the equivalent circuit of an induction motor. An approach has been proposed relying on the equation of an induction motor in three-phase fixed coordinate system obtained on the basis of the theory of generalized electromechanical converter. Несоответствие настроек системы  управления  фактическим  значениям  параметров частотно-регулируемого  асинхронного  электропривода  может  иногда  приводить  к  полной неработоспособности частотного электропривода, к существенному снижению динамических показателей качества. Такие параметры, как активное сопротивление и индуктивность ротора, индуктивность цепи намагничивания, недоступны для непосредственного измерения. При приемо-сдаточных испытаниях они не определяются, а величины, приводимые в каталогах и справочниках, являются расчетными и могут существенно отличаться от реальных значений конкретной машины. Несмотря на постоянные усилия исследователей, задача идентификации электромагнитных параметров схемы замещения асинхронного двигателя остается важной и актуальной. Авторы статьи разработали метод онлайн-идентификации электромагнитных параметров асинхронного двигателя, что позволит реализовать точную настройку регуляторов системы частотного управления при эксплуатационных изменениях характеристик приводного двигателя. Выполнен анализ установившегося режима работы асинхронного двигателя без использования Т-образной схемы его замещения. Предложен подход, опирающийся на уравнения асинхронного двигателя в трехфазной неподвижной системе координат, полученные на основе теории обобщенного электромеханического преобразователя. С учетом аналитических преобразований этих формул получена система нелинейных алгебраических уравнений четвертого порядка, решение которой позволяет определить активное сопротивление ротора, сопротивление рассеивания и главную взаимную индуктивность асинхронного двигателя в предположении, что активное сопротивление статора известно. Произведена верификация предлагаемого метода. На основании данных установившегося режима работы асинхронного двигателя типа 4А250М2УЗ выполнена идентификация его электромагнитных параметров, исследовано влияние начального приближения на точность полученных результатов, которые подтверждают работоспособность рассматриваемого метода идентификации

Modeliranje i simulacija međuzavojskog kvara asinkronog motora upotrebom SSFR testa za dijagnostičke svrhe

This paper presents a new idea to establish a simplified model of the short-circuit turns (SCT), in the stator winding of the squirrel-cage induction motor (IM) using standstill frequency response test (SSFR). This method may offer more precision in parameters estimation independent of variations in motor or load operating conditions since it is at standstill test. However, high-performance field-oriented control, or diagnosis purpose of the IM requires accurate knowledge of the electrical parameters. Furthermore, we propose to model the IM by a multiple cage equivalent circuit (EC) that enables us to take into account the deep bar effect with accuracy. The specific advantage of the proposed method that we can create a true SCT at several levels using fault simulator in order to estimate the EC model parameters in each case of fault severity, with a low probability of risk to the machine being tested, and a relatively modest expense. At the first time the healthy machine is identified and experimentally validated, then the models have been successfully used to study the transient and steady-state behavior of the IM with SCT fault, which a practically oriented scientific value.U radu je predstavljena nova ideja za uspostavljanje pojednostavljenog modela kratkospojenih zavoja (SCT) u namotu statora kaveznog asinkronog motora (IM) upotrebom testa frekevencijskog odziva u mirovanju (SSFR). Ova metoda moguće pruža precizniju procjenu parametara neovisno o varijaciji motorskih ili teretnih radnih uvjeta jer se testiranje provodi u mirovanju. Ipak, vektorsko upravljanje visokih performansi ili dijagnostička IM-a zahtijevaju točno poznavanje električkih parametara. Nadalje, predlažemo model IM-a s višekaveznom nadomjesnom shemom (EC) koja nam omogućuje da u obzir uzmemo točan efekt duboko pozicioniranih kaveznih štapova. Posebna prednost predložene metode je što možemo načiniti vjerodostojni SCT model na nekoliko razina upotrebom simulatora kvara da bismo procjenili parametre EC modela u različitim stadijima kvara, s malom vjerojatnosti rizika za korišteni stroj te relativno umjerene troškove. Prvo se identificira i eksperimentalno provjeri neoštećeni stroj, a zatim se modeli uspješno koriste za proučavanje dinamičkog i stacionarnog ponašanja IM-a s SCT kvarom što posjeduje praktično-orijentiranu znanstvenu vrijednost

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 Rotor Position Estimation For Brushless DC Motors

Brushless DC motor speed is controlled by synchronizing the stator coil current with rotor position in order to acquire an accurate alignment of stator rotating field with rotor permanent-magnet field for efficient transfer of energy. In order to accomplish this goal, a motor shaft is instantly tracked by using rotating rotor position sensors such as Hall effect sensors, optical encoders or resolvers etc. Adding sensors to detect rotor position affects the overall reliability and mechanical robustness of the system. Therefore, a whole new trend of replacing position sensors with sensorless rotor position estimation techniques have a promising demand. Among the sensorless approaches, Back-EMF measurement and high frequency signal injection is the most common. Back-EMF is an electromotive force, directly proportional to the speed of rotor revolutions per second, the greater the speed motor acquires the greater the Back-EMF amplitude appears against the motion of rotation. However, the detected Back-EMF is zero at start-up and does not provide motor speed information at this instant. There-fore, Back-EMF based techniques are highly unfavourable for low speed application specially near zero. On the other hand, signal injection techniques are comparatively developed for low or near zero motor speed applications and they also can estimate the on-line motor parameters exploiting the identification theory on phase voltages and currents signals. The signal injection approach requires expensive additional hardware to inject high frequency signal. Since, motors are typically driven with pulse width modulation techniques, high frequency signals are naturally already present which can be used to detect position. This thesis presents rotor position estimation by measuring the voltage and current signals and also proposes an equivalent permanent-magnet synchronous motor model by fitting thedata to a position dependent circuit model

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

Sensorless Commissioning and Control of High Anisotropy Synchronous Motor Drives

L'abstract è presente nell'allegato / the abstract is in the attachmen