Vibrations And Noises In Smal Electric Motors Measurement Analysis Interpretation Optimization

Controlling the level of noise in electrical motors is critical to overall system performance. However, predicting noise of an electrical motor is more difficult and less accurate than for other characteristics such as torque-speed. Recent advances have produced powerful computational methods for noise prediction, and Noise of Polyphase Electric Motors is the first book to collect these advances in a single source. It is also the first to include noise prediction for permanent magnet (PM) synchronous motors. Complete coverage of all aspects of electromagnetic, structural, and vibro-acoustic noise makes this a uniquely comprehensive reference. The authors begin with the basic principles of noise generation and radiation, magnetic field and radial forces, torque pulsations, acoustic calculations, as well as noise and vibration of mechanical and acoustic origin. Moving to applications, the book examines in detail stator system vibration analysis including the use of finite element method (FEM) modal analysis; FEM for radial pressure and structural modeling; boundary element methods (BEM) for acoustic radiation; statistical energy analysis (SEA); instrumentation including technologies, procedures, and standards; and both passive and active methods for control of noise and vibration. Noise of Polyphase Electric Motors gathers the fundamental concepts along with all of the analytical, numerical, and statistical methods into a unified reference. It supplies all of the tools necessary to improve the noise performance of electrical motors at the design stage.

"Today's electrical machines are finding many applications in new environments where lowernoise levels are demanded, especially in electric vehicles. It is, therefore, imperative thatthe designs must satisfy certain acoustic noise requirements. In the past, experimental electric motors were developed in the early design processto assess their noise performance before full scale production. This approach could bean unpleasant experience for motor designers, as the mitigation solutions often neededsubstantial modification to their prototype models. These prototypes can be very expensive, and forcing in engineering changes to an existing machine can be a nightmare. For thisreason, the use of computer software in noise and vibrations analysis has attracted a lot ofattention in recent years. This thesis uses computer-aided predictive techniques such as the finite element methodto set the background for the computational discussions and exploration of some of theresearch gaps in the literature. It focuses on the interior permanent magnet synchronousmotor due to its extensive application, particularly in the automotive industry. In this work, the effect of non-sinusoidal current waveforms on the acoustic noise field ofthe electric motor drive has been analyzed. It is discovered that sampling the airgap spaceat different instants yields inconsistent electromagnetic force results. Therefore, this thesisproposes an efficient way of extracting the electromagnetic forces in the airgap space toaccount for very critical harmonics that may be ignored in conventional techniques such asthe single-time sampling. It also defines two new acoustic quantities to accurately estimatethe resulting acoustic noise for different switching frequencies of the power electronic circuit. Also, since the thermal behavior of the electric motor is mostly linked to the lossesthat result from the current supply system, the analysis incorporates the role of temperaturein defining the acoustic field of the electric motor by adding an extra model to theexisting subsystem models in the noise calculation process. It reveals that elevating theoperating temperature levels significantly exacerbates the acoustic noise problems of themachine. The thermal excitation modified the electromagnetic, the structural and theacoustic subsystem models. Finally, the thesis addresses the computational burden associated with setting up multiphysicssimulation frameworks for the assessment of acoustic noise. Here, surrogate modelsare introduced as possible replacements of the time-consuming finite element simulations"--

The switched reluctance machine (SRM) is the least expensive electrical machine to produce, yet one of the most reliable. As such, research has blossomed during the last decade, and the SRM and variable drive systems using SRMs are receiving considerable attention from industry. Because they require a power electronic converter and controller to function, however, successful realization of an SRM variable drive system demands an understanding of the converter and controller subsystems and their integration with the machine. Switched Reluctance Motor Drives provides that understanding. It presents a unified view of the machine and its drive system from all of its system and subsystem aspects. With a careful balance of theory and implementation, the author develops the analysis and design of SRMs from first principles, introduces a wide variety of power converters available for driving the SRM, and systematically presents both low- and high-performance controllers. The book includes an in-depth study of acoustic noise and its minimization along with application examples that include comparisons between ac and dc drives and SRM drive. The result is the first book that provides a state-of-the-art knowledge of SRMs, power converters, and their use with both sensor-based and sensorless controllers. Switched Reluctance Motor Drives enables both students and engineers to learn all aspects of SRM drive systems and appreciate the interdependence of the various subsystems in performance optimization.