Torque Estimation of Synchronous Reluctance Machine using High Frequency Signal Injection

Il lavoro analizza due metodi per la stima della coppia prodotta da un motore sincrono a riluttanza, entrambi basati sull'iniezione di un segnale rotante di tensione ad alta frequenza sovrapposto al segnale sincrono alimentante il motore. A partire dal processo dei segnali ad alta frequenza si ottengono le induttanze ad alta freq e attraverso l'equazione di coppia si ottiene la sua stima. Sono state effettuate una simulazione in Simulink e un test sperimentale su un motore commerciale dell'ABB.ope

Uncovered Interest Parity in Central and Eastern Europe: Convergence and the Global Financial Crisis

This paper presents tests of uncovered interest parity in Croatia, the Czech Republic, Hungary, Poland and Romania; all countries in Central and Eastern Europe with floating exchange rates. Data are monthly and the trading horizon is three months. The estimations show that the UIP hypothesis is rejected for the full sample from 1999 to 2011 for all five countries. A number of reasons for the rejection were investigated. Rolling regressions show that standard versions of the UIP essentially lose all explanatory power in 2008-10, which was a period in which the global financial crisis led to instability in currency and interest markets in Central and Eastern Europe. Two indicators of global risk aversion were also found to enter significantly in the many UIP estimations. Finally, the size of the interest rates spread also seems to be of importance, at least for Poland and Romani

Machine learning-based method for linearization and error compensation of an absolute rotary encoder

The main objective of this work is to develop a miniaturized, high accuracy, single-turn absolute, rotary encoder called ASTRAS360. Its measurement principle is based on capturing an image that uniquely identifies the rotation angle. To evaluate this angle, the image first has to be classified into its sector based on its color, and only then can the angle be regressed. In-spired by machine learning, we built a calibration setup, able to generate labeled training data automatically. We used these training data to test, characterize, and compare several machine learning algorithms for the classification and the regression. In an additional experiment, we also characterized the tolerance of our rotary encoder to eccentric mounting. Our findings demonstrate that various algorithms can perform these tasks with high accuracy and reliability; furthermore, providing extra-inputs (e.g. rotation direction) allows the machine learning algorithms to compensate for the mechanical imperfections of the rotary encoder.Comment: This paper was submitted for publication to Measurement (Elsevier) on the 7th July 202

Uncovered Interest Parity in Central and Eastern Europe: Sample, Expectations and Structural Breaks

This paper examines the empirical validity of the hypothesis of uncovered interest parity (UIP) using data from five Central and Eastern European countries with floating exchange rates for the period 2003-2013. The analysis includes forward-looking as well as static expectations and also allows for different types of structural breaks. The variable representing deviations from UIP is stationary when expectations are forward-looking, but typically not when expectations are static even when structural breaks are incorporated. The results underscore the importance of the assumptions when the UIP hypothesis is tested

Proof of concept of a novel absolute rotary encoder

Rotary encoders are used in many applications that require monitoring or controlling mechanical systems such as robots. Typically, small rotary encoders have poor resolution; this is unfortunate for applications such as robotics in medical surgery procedures. For example, in an articulated robotic endoscope, miniaturization is mandatory and, when automation is desired, high accuracy to track the shape and pose of the device is required; small (few millimeters) and accurate (few hundred arcsec) rotary encoders are thus needed. Previously, we introduced a novel concept of a miniaturizable angular sensor, called ASTRAS (Angular Sensor for TRAcking System). This was presented as a basic element of a tracking system for articulated endoscopes. The principle of measurement of ASTRAS is based on processing a shadow image cast by a shadow mask onto an image sensor. The characterization of the first prototype of ASTRAS was very promising, however, its angular range of about ±30 degrees was too limiting for many practical applications. In this work, we present an extension of the concept mentioned above to a rotary encoder that can measure one full rotation of 360 degrees thus the name is ASTRAS360. Its working principle bases on encoding the shadow image using colored light to distinguish different angular sectors. The identification of the sector corresponds to a coarse angular measurement, which is afterward refined using the same technique as in ASTRAS. We implemented this concept, realizing a prototype and an algorithm to calculate the angle from the shadow image. The experiments demonstrated the validity of this concept and showed encouraging results with a precision of ∼0.6 arcsec and 6σ-resolution of 3.6 arcsec corresponding to 19 bits

Torque Estimation of Synchronous Reluctance Machine using High Frequency Signal Injection

Il lavoro analizza due metodi per la stima della coppia prodotta da un motore sincrono a riluttanza, entrambi basati sull'iniezione di un segnale rotante di tensione ad alta frequenza sovrapposto al segnale sincrono alimentante il motore. A partire dal processo dei segnali ad alta frequenza si ottengono le induttanze ad alta freq e attraverso l'equazione di coppia si ottiene la sua stima. Sono state effettuate una simulazione in Simulink e un test sperimentale su un motore commerciale dell'ABB

Equilibrium exchange rate of the Estonian kroon, its dynamics and impacts of deviations

The aim of the analysis presented here is to examine the behaviour of the real exchange rate of the Estonian kroon, to estimate its equilibrium value and investigate its impact on the competitiveness of Estonian economy. A brief account on possible measures of the real exchange rate (RER) is given, and then the real effective exchange rate (REER) weighted with domestic and foreign consumer price indices (CPI) is chosen for the estimation. A model for the equilibrium real exchange rate (ERER) determination suitable for a small open economy as Estonia is outlined and provides a theoretical basis for understanding what kind of fundamentals can affect real exchange rate behaviour. Given the short sample considered here, a single equation estimation method is used. The choice of fundamentals is determined both by particular features of the Estonian economy and data constraint. The fundamentals finally adopted are productivity differential between tradeables and nontradeables sectors, investment share, resource balance and nominal effective exchange rate. Having detected the existence of one cointegration vector between RER and fundamentals, it is possible to estimate the long-run relationship linking them and an error correction mechanism in order to have some information on short-run behaviour of the real exchange rate. Estimation results are then used to construct both ERER series and misalignment measures. To do this, some hypotheses on equilibrium/sustainable levels of fundamentals are set and discussed. Our simulation hence brings us to conclude that an appreciation of RER in the sample period occurred together with an appreciation of its equilibrium level. The latter appreciated slower, hence the initial undervaluation was corrected and the difference between RER and its equilibrium level shrank, leading to a slight overvaluation after the Russian crisis.