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The article compares the test results for gimballess electrostatic gyroscopes containing rotors with a light-contrast pattern applied to titanium nitride (TiN) coating or to beryllium. The criteria for comparing the devices with different types of rotors are proposed and justified. The need to modify the rotor manufacturing technology in order to improve the rotor design and mature some technological operations is analyzed. It has been shown that at a certain stage it is rational to mark the raster pattern on the titanium nitride coating, and currently the pattern can be again applied directly to the rotor beryllium surface. [ABSTRACT FROM AUTHOR]

Abstract Solid rotor induction motors (SRIMs) are asynchronous motors suited for high speed applications. This work presents an experimental case study where standard loss segregation procedures for induction motors are performed with a two-phase smooth solid rotor induction motor in order to verify their applicability. Even though the machine is supposed to operate at high frequency, the tests are performed at reduced frequency and voltage in order to avoid the effects of time harmonics. An adjustment in the separation of losses is proposed to contemplate the effects of the high no-load slip, and the behavior of the stray losses under high per-unit slip is analyzed in a load test. The test results are finally extrapolated for the rated condition.

A typical flywheel energy storage system (FESS) includes an electrical machine, a flywheel, and magnetic bearings, which are independent of each other. Therefore, the structure of FESS is complicated, which leads to the problems of high cost and low integration. This article presents a novel stator PM excitation solid rotor machine (SPE-SRM) for FESS, which integrates an electrical machine, flywheels, and a magnetic bearing. The design method of the SPE-SRM is presented specifically. First, the structure and operation principle of the SPE-SRM are illustrated. Second, the design and optimization of the flywheel-rotor are presented with considering of power, energy storage, and mechanical strength. Third, the magnetic equivalent circuit of the SPE-SRM is established to simplify the design. Besides, the armature reaction and leakage flux factor are investigated. Fourth, the performance indexes, including torque, suspension force, no-load back electromotive force (back-EMF), losses, and temperature rise are fully analyzed by the finite element analysis. Finally, a 22 kW prototype is manufactured and tested. The rationality of the concept and design is validated by experiments. The SPE-SRM has the merits of high integration, robust structure, and low cost, so it has the potential for wide application in FESS. [ABSTRACT FROM AUTHOR]

Solid rotor induction motors (SRIMs) are asynchronous motors suited for high speed applications. This work presents an experimental case study where standard loss segregation procedures for induction motors are performed with a two-phase smooth solid rotor induction motor in order to verify their applicability. Even though the machine is supposed to operate at high frequency, the tests are performed at reduced frequency and voltage in order to avoid the effects of time harmonics. An adjustment in the separation of losses is proposed to contemplate the effects of the high no-load slip, and the behavior of the stray losses under high per-unit slip is analyzed in a load test. The test results are finally extrapolated for the rated condition. [ABSTRACT FROM AUTHOR]

This paper presents the Park model of a solid-rotor induction motor. In this model, the dynamic state of the motor is described by integer and noninteger order differential equations. The skin effect in the solid rotor was represented by resistance and inductance with lumped constants, and the fractional inductance was dependent on the frequency of the eddy current induced in the rotor. The parameters of the equivalent circuit were determined by the standstill frequency response test with the stationary machine on the basis of the finite element method analysis of the electromagnetic field. A simulation of the dynamic states of the induction motor with a solid rotor was carried out based on the calculated parameters. The simulation was carried out using a program written in the Matlab environment. The simulations show that the electromagnetic moment during the motor start-up is about 2 times greater than the initial torque in the steady state. On the other hand, the maximum value of the stator current during the start-up is about 1.5 times greater than the effective value of the inrush current in the steady state. A good agreement was obtained between the results calculated from the distribution of the magnetic field by the finite element method and the results obtained on the basis of the equivalent circuit and, in the case of the electromagnetic torque, with the results obtained from the transient state during motor reversal. [ABSTRACT FROM AUTHOR]

The rotor temperature rise of high voltage line-start solid rotor permanent magnet synchronous motors (HVLSSR-PMSMs) may be too high while operating, which properly causes thermal demagnetization for permanent magnets. Therefore, it is necessary to perform the thermal investigation on HVLSSR-PMSM. In this article, a 315-kW, 6-kV HVLSSR-PMSM with the air-cooled hybrid ventilation system is studied in the view of thermal phase. The losses, obtained from the electromagnetic analyses, are applied to the thermal investigation as the distributed heat sources. Whereas, both the mathematical and the geometrical models are proposed for the three-dimensional (3-D) fluid-thermal coupled investigation, from which the fluid velocity and the temperature in motor different components are determined. Whereas, with the hybrid ventilation system, temperatures in motor different components reduce, obviously comparing with those in motor with the original cooling system. The experimental investigations are performed on prototypes in both cases, which verify the calculation results and approve the effectiveness of the proposed hybrid air cooling system as well. [ABSTRACT FROM AUTHOR]

This paper presents the Park model of a solid-rotor induction motor. In this model, the dynamic state of the motor is described by integer and noninteger order differential equations. The skin effect in the solid rotor was represented by resistance and inductance with lumped constants, and the fractional inductance was dependent on the frequency of the eddy current induced in the rotor. The parameters of the equivalent circuit were determined by the standstill frequency response test with the stationary machine on the basis of the finite element method analysis of the electromagnetic field. A simulation of the dynamic states of the induction motor with a solid rotor was carried out based on the calculated parameters. The simulation was carried out using a program written in the Matlab environment. The simulations show that the electromagnetic moment during the motor start-up is about 2 times greater than the initial torque in the steady state. On the other hand, the maximum value of the stator current during the start-up is about 1.5 times greater than the effective value of the inrush current in the steady state. A good agreement was obtained between the results calculated from the distribution of the magnetic field by the finite element method and the results obtained on the basis of the equivalent circuit and, in the case of the electromagnetic torque, with the results obtained from the transient state during motor reversal.

Solid-rotor switched reluctance machines (SRM), having the rotor machined from a single piece of metal, are one of the few viable options for motoring and/or generation under harsh operating conditions, including high speeds, high shaft temperature, and corrosive environment. Apart from double saliency and high degree of magnetic saturation as in any SRM, significant core losses due to high eddy currents, even under static conditions, make the characterization and modeling of solid-rotor SRM challenging. The objective of this article is to understand the magnetic characteristics of a solid-rotor SRM through extensive experimental studies and to develop a stator-side model for the machine which adequately captures its magnetic behavior. First, the flux-linkage characteristics of the solid-rotor SRM under test are measured over a wide range of excitation conditions and rotor positions. Applying a computationally efficient decomposition technique on each set of experimental data, the measured winding current is resolved into magnetizing and core-loss components to obtain a stator-side model of the machine. The proposed model is useful to predict the winding current and core-loss under different excitation conditions, which is necessary for simulation and performance prediction. The proposed method is more accurate than the existing methods, while being simple and fast to implement. [ABSTRACT FROM AUTHOR]

Aiming at the shortcomings of the analytical algorithm and numerical algorithm for calculating the eddy current losses in the solid rotor of high speed squirrel cage induction motor, this study proposes a semi‐analytical algorithm. Based on the magnetic field of the rotor surface and Maxwell's equations, the analytical formula of this algorithm is derived. According to the law of energy conservation, the losses in rotor and rotor bars are calculated, respectively, so that the eddy current losses in the solid rotor are calculated indirectly. Taking a high speed squirrel cage induction motor as an example, the eddy current losses in the solid rotor are calculated by the semi‐analytical method. The calculation result is verified by the two‐dimensional transient finite‐element method, and the calculation result meets the basic requirements of engineering practice. [ABSTRACT FROM AUTHOR]

Solid rotor induction machines are still used in high-speed systems. A two-dimensional field-circuit model based on the finite element method and the complex magnetic vector potential has been shown as a very time-effective tool in the analysis of their steady states compared to time-domain models. This continuation work presents a validated computational algorithm that enables the inclusion of the nonsinusoidal and/or asymmetrical voltage supply in the multi-harmonic field-circuit model of these machines that was presented in the previous works by the authors. The extended model accounts for both spatial harmonics due to slotting and/or winding distribution and the time-harmonics due to voltage waveform. The applicability range of the model therefore increases to cases when the machine is supplied with a nonsinusoidal three-phase system of voltages with symmetry or asymmetry that can be decomposed into three symmetrical components. Its short execution time characteristic allows for much more insightful design studies of the contribution of voltage supply- and slotting-related harmonics to the overall efficiency of the machine than is possible with the time-consuming time-domain models. The proposed computational framework has never been presented in the literature. The model is verified positively by the comprehensive time-domain model. It is especially useful in design studies on solid rotor induction motors related to the optimisation of the efficiency of induction motor-based drive systems.

Modifying the equivalent rotor resistivity with rotor end factor in 2-dimension (2-D) finite element analysis (FEA) is an effective way to analyze the 3-dimension (3-D) solid rotor problems. For the smooth solid rotor, five different rotor end factors are discussed and compared with each other. It is theoretically clarified that the resistivity of rotor in 2-D FEA should be multiplied by the square of rotor end factors to take the 3-D end effect of solid rotor into account. For the slitted solid rotor, an improved rotor end factor is proposed based on the equivalent area algorithm of eddy currents in rotor, since the end factors of smooth solid rotor are not applicable. Finally, the time-harmonic finite element method (FEM) combined with the rotor end factor is applied to analyze the performance of solid rotor induction motor. The tested and computed results are in good agreement, which proves the effectiveness of rotor end factor for the simplication of 3-D solid rotor problems.

The paper presents a comparison of higher harmonics in induced phase voltages of a stator winding in the no-load state of a three-phase 5.5 kVA salient pole synchronous generator. The comparison is carried out for the synchronous generator with different salient pole rotor constructions: a non-skewed solid rotor, a non-skewed solid rotor with radial incisions, and a laminated electrotechnical steel rotor with skewed slots and damping bars. The calculations of higher harmonics are based on the magnetic field distributions in the air gap, which are carried out in a 2D model in a FEMM program and on the induced voltage waveforms in the stator windings registered during experimental investigations of the 5.5 kVA salient pole synchronous generator in the no-load state.

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Technical Electrodynamics / Tekhnichna Elektrodynamika is the property of National Academy of Sciences of Ukraine, Institute of Electrodynamics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study proposes a novel dual stator composite rotor axial flux induction motor (DSCRAFIM) whose solid rotor is coated with copper layers. A novel multi‐slice and multi‐layer method is developed and applied to analyse the three‐dimensional electromagnetic field distribution in DSCRAFIM. In the application of this analytical method, DSCRAFIM is equivalent to a finite set of equal‐width and increasing‐length double primary composite secondary linear induction motors, whose steel secondary is divided into a finite set of equal‐height layers. The surface impedance theory is applied to derive the improved equivalent circuit model (IECM) of DSCRAFIM, which considers the coupling relationship between dual stator windings. The accuracy of this IECM is then verified by both finite‐element analysis and experimental test. [ABSTRACT FROM AUTHOR]

For line start permanent magnet synchronous machines (LSPMSMs), the eddy current loss in the rotor, which has of significant effects on rotor working temperature, may cause thermal demagnetization to permanent magnet. Therefore, this paper addresses an investigation on the temperature distribution in LSPMSM based on a 6 kV, 315 kW prototype with solid starting cage bar. Firstly, the loss distributions, obtained from a 2-D transient electromagnetic field calculation, are determined as the distributed heat source in thermal analyses. Then, the fluid-thermal coupled analyses are performed, by which the temperature distributions in the machine are determined. Meanwhile, the calculated motor performance is verified via comparison with the measured results. The calculation results show that the temperatures in the rotor core and permanent magnets are relatively high. To find the solution for reducing the rotor working temperature, a rotor air slot structure was proposed in this analysis. The theoretical calculation indicates that the rotor working temperature reduction is obvious with the rotor air slot in the machine. Therefore, the operating situation of solid rotor LSPMSM could be improved effectively with the proposed rotor thermal solution, which also benefits the machine reliability and safety. [ABSTRACT FROM AUTHOR]

The paper presents the closed-form solution of two dimensional (2D) electromagnetic wave equation for eddy current problems in cylindrical structures. The magnetic field calculation is a complex issue for electrical machines especially. The paper provides an analytical solution for solid cylindrical structures with linear magnetization. This approach is extended to the electrical machines with the solid rotors. Multilayered cylindrical geometry is used for the solution. Two dimensional parabolic partial differential equation is solved for each layer. According to the analytical solution, eddy current and eddy current losses are calculated in the solid region and compared to the results of the finite element model. [ABSTRACT FROM AUTHOR]

This study presents a composite multilayer method (CMM) to evaluate the performance of a two‐degree‐of‐freedom (2DoF) direct drive induction motor (2DoFDDIM) whose solid rotor is coated with a copper layer. It includes a rotary part and a linear part. Based on the traditional multilayer theory, a complete 2DoFDDIM CMM computer program importing propagation constants is built. Due to the complex magnetic field in a 2DoFDDIM, this study mainly analyses it from the perspective of a single DOF motor. An equivalent circuit for the rotary part of the 2DoFDDIM is then derived applying CMM and the 2D magnetic field distribution is obtained by solving Maxwell's equations in motor layers. The developed torques, power factors and stator currents of the rotary part with different slips and the latter two of the linear part at zero speed are calculated by CMM, which are then compared with results from the finite element method (FEM) and experimental results. The computation time of the CMM is far less than that of the FEM. The acceptable accuracy confirms the effectiveness of the CMM for analysis and performance calculations of the 2DoFDDIM. [ABSTRACT FROM AUTHOR]

Due to the solid rotor structure, High-Voltage Line-Start Solid Rotor Permanent Magnet Synchronous Motor (HVLSSR-PMSM) operates with high rotor temperature rise. If the ventilation path cannot take the rotor heat away in time, the rotor will overheat or even may led to the thermal demagnetization for permanent magnet. Therefore, it is of great significance to study the thermal issues of HVLSSR-PMSM. In the paper, the fluid field and temperature field of a 315 kW, 6 kV HVLSSR-PMSM with air-cooled hybrid ventilation systems are investigated. Firstly, the electromagnetic analysis of the machine is done by using the finite-element method, the loss distributions then are obtained, which will be assigned as the heat source for thermal analysis. Then, the three -dimensional (3-D) fluid thermal coupled mathematical model for thermal analysis of HVLSSR-PMSM is established. The temperature field and the fluid flowing state of HVLSSR-PMSM with single ventilation path air-cooled system are investigated by using the established 3D fluid thermal coupled mathematical model. A dual ventilation path air-cooled system for HVLSSR-PMSM is proposed to reduce the operating temperature rise. Then, the temperature field and fluid field of HVLSSR-PMSM with dual ventilation system are analyzed by comparing with single ventilation system. Moreover, the temperature experiments are carried out on the machine with dual ventilation system to validate the accuracy of the established mathematical models. The results show that the proposed dual ventilation path air-cooled system can effectively improve the thermal distribution of HVLSSR-PMSM, whilst it can also reduce the working temperature rise of the machine.

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A two degrees of freedom (2-DOF) actuator capable of producing linear translation, rotary motion, or helical motion would be a desirable asset to the fields of machine tools, robotics, and various apparatuses. In this paper, a novel 2-DOF split-stator induction motor was proposed and electromagnetic structure parameters of the motor were designed and optimized. The feature of the direct-drive 2-DOF induction motor lies in its solid mover arrangement. In order to study the complex distribution of the eddy current field on the ferromagnetic cylinder mover and the motor's operating characteristics, the mathematical model of the proposed motor was established, and characteristics of the motor were analyzed by adopting the permeation depth method (PDM) and finite element method (FEM). The analytical and numerical results from motor simulation clearly show a correlation between the PDM and FEM models. This may be considered as a fair justification for the proposed machine and design tools. [ABSTRACT FROM AUTHOR]

This paper presents the design process, detailed analysis, and prototyping of a novel-structured line-start solid-rotor-based axial-flux permanent-magnet (AFPM) motor capable of autostarting with solid-rotor rings. The preliminary design is a slotless double-sided AFPM motor with four poles for high torque density and stable operation. Two concentric unilevel-spaced raised rings are added to the inner and outer radii of the rotor discs for smooth line-start of the motor. The design allows the motor to operate at both starting and synchronous speeds. The basic equations for the solid rings of the rotor of the proposed AFPM motor are discussed. Nonsymmetry of the designed motor led to its 3-D time-stepping finite-element analysis (FEA) via Vector Field Opera 14.0, which evaluates the design parameters and predicts the transient performance. To verify the design, a prototype 1-hp four-pole three-phase line-start AFPM synchronous motor is built and is used to test the performance in real time. There is a good agreement between experimental and FEA-based computed results. It is found that the prototype motor maintains high starting torque and good synchronization. [ABSTRACT FROM PUBLISHER]

Pole‐changing of line‐start permanent magnet (LSPM) motors at start‐up eliminates all their drawbacks such as poor starting torque, vibration at start‐up and synchronisation problems. In addition, by using this method almost all the inherent limitations in the design parameters of line‐start motors such as rotor resistance, permanent magnet strength and mechanical stress influenced by pulsating torques are alleviated. Therefore there is no need to compromise between the motor parameters. In this study, the design procedure of these motors is investigated and a high‐performance motor based on the pole‐changing starting‐method is designed and fabricated. Next, the possibility and advantages of replacing laminated cage‐bar rotors with solid rotors are investigated for pole‐changing LSPM motors. Then, simulations are done by the two‐dimensional finite element method and finally, the experimental results are presented. The good agreement between simulation and experimental results validates the theoretical method and also the new design. [ABSTRACT FROM AUTHOR]

The paper deals with analytical method of design and prediction of performance characteristics for induction motors with solid steel rotor coated with copper layer. On the basis of the distribution of the 2-D electromagnetic field, the equivalent impedance of the rotor has been derived. The edge effect and nonlinear magnetic permeability of solid steel have been included. The presented analytical method has been verified with laboratory test results. A 300 kW, 60 000-rpm, three-phase solid-rotor induction motor for the next generation air compressor has been investigated. The accuracy of analytical approach is acceptable and can be recommended for rapid design of solid-rotor induction motors. [ABSTRACT FROM PUBLISHER]

A finite element method, coupled field-circuit, is applied to design a solid rotor induction motor in this paper. And a model coupled with field-circuits has been set up for considering the velocity effect, eddy current effect and non-linear property. A new end-region coefficient is presented to correct the effect of end region. It makes designed results of the motor more accurate. The method makes the period of design short and saves hardware from computing three-dimensional non-linear model. The comparison between tested and computed results proves that the method has higher accuracy and validity. [ABSTRACT FROM AUTHOR]

Problems of mathematical modeling the induction capacitor motors with the solid ferromagnetic rotor made by powder metallurgy methods are considered. The method of the solution of the two-dimensional field problem with the use of the fast Fourier transformation is presented. The results of the solution of the problem and the analysis of the obtained results are given. [ABSTRACT FROM AUTHOR]

This paper investigates the suitability of solid-rotor induction-motor technology for a natural-gas-compression application with a high power output. To this end, a new solid-rotor design for an 8-MW 6.6-ky 12 000-min-1 motor without any copper parts in the rotor was developed, and the motor performance was tested. In this paper, solid-rotor material selection, rotor slitting, and the end effects of the purely solid rotor are discussed. A frequency-dependent end-effect correction factor is introduced, and a method for the rotor-end-leakage correction is presented. The performance of the proposed end-effect correction factor is verified by comparing the calculated torque and power factor with the measured values. [ABSTRACT FROM AUTHOR]

Abstract: A computer model, including analytical and FEM formulations, was developed to calculate the starting performance of synchronous motors with solid rotor salient poles. Using quasi-steady state equations, the average and the envelope of the oscillating electromagnetic torque as well as the stator rms current are calculated. With the stator current, the rotor pole losses are evaluated by FEM. The complete simulation process is performed by self-contained software composed by several computational modules properly tiled to simplify the work of a design engineer. The calculated starting performance was compared to experimental results showing satisfactory consistency. [Copyright &y& Elsevier]

A high-conductivity shield is often used for coating the rotor of solid-rotor synchronous machines for reducing the surface eddy-current losses due to armature-reaction space/time harmonics and/or tooth ripple. Since the design process for determining the optimal shield thickness can be complicated and time consuming, a simple analytical model based on Maxwell's equations was developed and presented in a previous paper to simplify the process. It has been shown that such an analytical tool can be used as a quick and effective "screening tool" for determining the range of the optimal shield thickness for minimizing rotor surface losses; however, the influence of finite rotor axial length including the end-face losses was not taken into account. In this paper, an additional step is introduced in the shield design process where a special finite-element (FE) method that accounts for the impact of finite rotor axial length is employed for refining the design obtained from the analytical solution. Comparisons are made for a number of shield thicknesses and rotor lengths for significant space and time harmonic combinations to verify the validity of the proposed two-step design process (analytical and FE) and to evaluate the impact of the finite length of solid rotors. [ABSTRACT FROM AUTHOR]

This paper presents a comparison between three architectures of line-start PM motors for oil-pump application. This paper is focused on the performances in synchronous operation as well as the self-starting operations. Effects of electrical parameters on the starting and steady performance characteristics are demonstrated to find a satisfying design to meet required performances, it seems that the interior permanent magnet motor yields an impressive starting performance. [ABSTRACT FROM AUTHOR]