Control algorithm to improve the vibronoise characteristics of synchronous multi-phase magnetoelectric electric drive

Vibrations and noises occur during the operation of synchronous motors. To reduce them, more advanced engine designs and special control algorithms are used. The application of a multiphase (m > 3) synchronous motor design allows you to influence the configuration of the magnetic field in a wider range. Thus, the task to develop a control algorithm that improves the vibration-noise characteristics of a multiphase motor is relevant. The finite element method is used to calculate the magnetic field in a 2D formulation, implemented in the Elcut software package. Also, the simulation methods with the MatLab Simulink package are applied. The authors suggest the algorithm to control multiphase synchronous motors with permanent magnets that reduces the level of vibrations. Improvement of vibration-noise characteristics is achieved when the motor is supplied with currents of the certain form, and they compensate the pulsation of electromagnetic forces that occur between various parts of the electric machine. This algorithm is based on the measurement of the electromagnetic forces and the torque directly in the process of control. The results of modeling the operation of the engine with the developed control algorithm are presented. The authors have compared the characteristics obtained using the developed control algorithm and the characteristics that correspond to the sinusoidal source supply. The vibration-noise characteristics of a permanent magnet synchronous motor can be improved by using the control system. This control system generates currents in an appropriately synthesized form. In this case, the power consumption will increase slightly.

Analytical Model to Calculate Radial Forces in Permanent-Magnet Synchronous Machines

There are three principal sources of noise and vibration in electrical machines: electromagnetic sources, mechanical sources, and aerodynamic sources. Nowadays, one of the major advantages of permanent-magnet synchronous machines is their torque density. This density is achieved through a high magnetic flux density in the air gap, which is achieved through hard magnets. Unfortunately, in these machines, electromagnetic forces have been identified as the main source of vibration and noise, and high magnetic flux densities make these vibrations and noises more significant. With the aim of better understanding the relationship between electromagnetic forces and design variables, this article, which is the continuation of previous work, firstly describes a study of the sources of magnetic forces in permanent-magnet synchronous machines. Subsequently, an analytical model for the computation of the radial forces originating from electromagnetic sources in permanent-magnet synchronous machines is stated. This model analyzes the forces on both the rotor surface and the base of the stator tooth. The analytical results were corroborated through simulations using the finite element method (FEM) and also by experimental tests performed over two prototypes. The results achieved by the analytical model show good agreement with both FEM results and experimental measurements.

Estimation of compressive and tensioning forces in linear storages of electric power

Object and purpose of research. Electromagnetic forces in thin-walled coils of toroidal type and common type of different cross-sections (circular, rectangular, disk, spherical) are estimated and compared. Materials and methods. Methods of theoretical electric engineering are used. Main results. It is established that forces for toroidal and common coils have different character. First, there is an effect of centripetal compression, secondly, there is an effect of centripetal tensioning. Conclusions. These effects should be taken into account in the coil design, which have to withstand deformation or damage under compressive or tensioning forces.

Practical Modal Analysis of a Prototyped Hydrogenerator

The vibration on the stator core of hydrogenerators caused by electromagnetic forces is an important factor affecting the reliability and long-lasting operation of a machine. For a suitable addressment of the problem, it is necessary to accurately predict the eigenmodes and eigenfrequencies of the mechanical system. However, different results for the eigenfrequencies can be achieved depending on the applied model and material parameters. This work contributes to solving this issue by investigating the impact of different input parameters on the eigenmodes and eigenfrequencies calculated by analytical and numerical models. The results are discussed and compared to measurements performed on a prototyped 732 kVA hydrogenerator.

Removal of Inclusions from Melts

Inclusion origins and the methods for determining the content of inclusions in a melt are described. Removal of inclusions by flotation/settling is demonstrated. The method for removing inclusions from molten metals by bubbling is described in detail with attachment mechanism to bubbles. Use of microbubbles are included. Filtration capture mechanisms of inclusions, cake and deep bed mode, are derived. A model for removal of inclusions by ceramic foam filters is introduced. Re-entrainment of inclusions are examined. In addition the use of rotational and electromagnetic forces to remove inclusions is explained. The number size distribution of inclusions is taken into account, both the change in the distribution function and the growth of inclusions with time. In the end the interaction of dissolved elements and inclusions is described.

Electromagnetic Analysis and Experimental Study to Optimize Force Characteristics of Permanent Magnet Synchronous Generator for Wave Energy Converter Using Subdomain Method

This paper presents an electromagnetic analysis and experimental verification to optimize the noise, vibration, and harshness (NVH) characteristics of a permanent magnet synchronous generator (PMSG) for wave energy converters (WECs). WECs applicable to breakwater installed in island areas require a wider operating range and a robust design for maintenance compared with wind-turbine systems. Owing to the use of a permanent magnet with a high energy density, the PMSG has a higher power density than other types of generators; however, strong electromagnetic excitation forces that affect the NVH characteristics are generated. Therefore, in this study, the electromagnetic forces are analyzed through an electromagnetic-field analysis using a subdomain analytical method. Based on the analytical solution, electromagnetic forces were determined. Four electromagnetic excitation forces were classified, and the methods for reducing electromagnetic excitation forces are presented here. Finally, a method for evaluating the system resonance through electromechanical analysis is presented. The proposed analysis, optimization, and experimental study are validated through comparison with finite-element analysis and experimental results.

An analytical model for predicting noise radiated by switch reluctance electric motors

Switch reluctance motors (SRM) have become a prominent alternative for electric vehicles in recent years due to their simple, high power density architecture and cost-effective manufacturability. Despite its potential, NVH problems have been one of the biggest challenges for SRM's implementation. Vibration and noise generated by the SRM are mainly caused by phase switching related torque ripple, unbalanced electromagnetic forces from air gap variations and lamination problems. Our proposed model is an analytical noise radiation prediction model which relates geometrical, material and electrical design inputs to radiated sound power. The electromagnetic part of the model is nonlinear with saturation and provides back-emf and flux linkage by receiving design inputs. The computed magnetic energy, radial and tangential rotor forces are utilized as excitation sources to a continuous shell dynamic model to obtain the steady-state vibration response. Finally, surface velocities obtained from the shell model are used to calculate sound power. Utilizing a shell structure provides axial, radial and tangential information on the casing by considering the effect of magneto-restrictive forces of laminations, torque ripples and unbalanced electromagnetic forces. The effect of air gap, lamination error, and stator and rotor geometry on sound radiation are studied through an example case study.

Use of a transient SEA for calculation of structure-borne interior noise in trains from an induction motor controlled by multi-mode PWM

This paper presents a transient SEA (Statistical Energy Analysis) approach to predict the structure-borne interior noise in trains from an induction motor controlled by multi-mode PWM (Pulse Width Modulation). Most of the induction motors installed in trains are controlled by multi-mode PWM, which switches between asynchronous and synchronous modes according to the speed to reduce switching losses. This control causes the electromagnetic forces of PWM harmonics to change, resulting in a transient interior noise depending on the vehicle's speed. In this paper, we model the bogie using FEM to calculate the transmission of the electromagnetic forces to the vehicle body through traction bars and dampers. Next, we model the vehicle body using a transient SEA to calculate transient energy in a 1/3 octave band excited by the transmitted electromagnetic forces. Finally, we restore the waveform of interior noise by applying the appropriate phase to the transient energy to auralize the analysis result. We obtained reasonable agreement by comparing the analysis results of the interior noise with the actual measurements.