Carlos Verucchi

Effects of partial rotor demagnetization on permanent magnet synchronous machines

The effects of magnet faults on the rotor of permanent magnet synchronous machines are analyzed in the present work. In particular, demagnetization effects are analyzed using the finite element method. Two different stator winding configurations are considered in the analysis, series and parallel connected windings. From this analysis, a fault detection strategy based on the information contained in winding-current spectrum is proposed. A fault severity factor is also proposed to quantify residual magnetism losses (demagnetization) on a single magnet. This factor is practically independent from the motor load conditions. Experimental results are presented to validate the proposal.

Fault Detection and Diagnosis Techniques in Induction Electrical Machines

A GREAT AND VARIED DEAL OF APPROACHES FOR FAULT DETECTION AND DIAGNOSIS IN INDUCTION MACHINES HAS BEEN PROPOSED AND IMPLEMENTED IN THE LAST YEARS. THESE NEW TECHNIQUES ARE ATTRACTIVE DUE TO THEY ARE CHARACTERIZED BY THEIR ON-LINE AND NON-INVASIVE FEATURES. THAT IS, THE ABILITY OF DETECTING FAULTS WHILE THE MACHINE IS UNDER NORMAL RUNNING AND WITHOUT NEEDING TO MOUNT SENSORS WITHIN THE MOTOR. THESE FEATURES, INHERENT OF THE NEW TECHNIQUES, DISTINGUISH THEM FROM THE TRADITIONAL ONES, WHICH MAINLY REQUIRE THAT THE MACHINE UNDER STUDY IS OUT OF SERVICE IN ORDER TO YIELD A DIAGNOSIS. THE PURPOSE OF THIS ARTICLE CONSISTS THEN IN REVIEWING THE PRINCIPAL ALTERNATIVES IN THE FIELD OF FAULT DIAGNOSIS FOR INDUCTION MACHINES AND TO COMPARE THEIR PERFORMANCE TAKING INTO ACCOUNT THE REQUIRED DIAGNOSTIC INFORMATION, THE NUMBER AND IMPORTANCE OF THE FAULTS THEY CAN DETECT, THEIR SPEED TO ANTICIPATE A FAULT AND THE CERTAINTY DEGREE IN THE FINAL DIAGNOSIS.

High Efficiency Electric Motors: Economic and Energy Advantages

The energy crisis that is currently being faced by humanity has demanded the revision of the regulations applied to different energy consumers, including electrical machines. The minimum efficiency standards for electrical machines provided by the regulations have been increased. Different categories have been defined to identify the engine based on the level of losses. Regardless of the benefits of ecological nature imposed by recent regulations, the use of the new generations of high efficiency induction engines is attractive from an economic standpoint. The lower power consumption engines and its increasing life span can allow quickly recovering the additional cost of new units and achieving further gains. In this paper the current regulations in different countries of the world are reviewed. According to the energy cost in Argentina, a computation of the times of economic payback is also presented.

A Model For Permanent Magnet Synchronous Machines With Demagnetization Faults

An analytical model for permanent magnet synchronous machines with demagnetization faults is proposed. Using this model, the effects of fault on the induced EMF for different winding configurations are analyzed. The results are validated for two winding configurations by a finite element model. Finally, experimental results for a machine with demagnetization are presented to validate the proposal.

Fault detection in gear box with induction motors: an experimental study

The failures in reducing speed gearboxes or speed multipliers with gears have traditionally been diagnosed by means of vibration analysis. Recently there has been noticed the possibility of making a diagnosis based on the tracking of the stator current of the motor driving the box or its electromagnetic torque. These variations, unlike vibration studies, have the advantage of being non-invasive. This work aims to evaluate the ability of fault detection and diagnosis from the spectral analysis of the torque. On an actual application, the behavior of the frequencies associated with the fault according to the engine load condition is analyzed. Conclusions about the possibility of detecting failures of different severity over a tooth of a toothed wheel are obtained.

Efficiency Measurements in Induction Motors: Comparison of Standards

Recently, given the need to reduce the emission of greenhouse effect gases and limiting the steady increase in energy demand, were have proposed new standards of efficiency levels of electric motors. From them have been defined efficiency categories, which determine the limits for so called Standard Efficiency Motors, High Efficiency, Efficiency Premium, etc. Most countries, therefore, have established legal restrictions on the use of motors with low efficiency. A small error in the motor efficiency measurement could lead to an incorrect categorization. In this sense recently have been revised standards that establish testing procedures. Each one, in turn, provides different alternatives more or less accurate to estimate the motor efficiency based on the tools that are included (dynamometer torque sensor, windings temperature measurement, etc.). In this paper a comparison of some of the most commonly used standards for the motor efficiency measurement is presented. The comparison is made in reference to the so-called direct method, where the input and output power of a motor is directly measured with a strict control of ambient (laboratory), engine temperature and feeding conditions. The comparisons allow conclusions about the probable errors in the application of each standard.

Detección y diagnóstico de problemas de desmagnetización y desbalance mecánico en máquinas síncronas de imanes permanentes

A new strategy for the detection and isolation of asymmetric demagnetization and mechanical imbalance problems in permanent magnet synchronous generators operating at steady-state is proposed in this paper. The strategy is based on measuring the voltage at the midpoint of the phase windings. Particularly, the presence of demagnetization faults is reflected in the midpoint voltage spectrum frequency as sidebands around the fundamental component. On the other hand, in the case of mechanical imbalance faults, these sidebands will be reflected in both, thus allowing the detection and separation from the type of fault present, as well as quantify each.