Torque Characteristics Analysis Research Articles

Multi-mode operations of double-stator switched reluctance machine for electric vehicle

PurposeThe purpose of this paper is to introduce a double-stator switched reluctance machine (DS-SRM) for electric vehicles (EVs) and to propose multi-mode operations for this machine.Design/methodology/approachAnalysis of flux linkage distributions and torque characteristics using finite element method (FEM). Building a dynamic simulation model based on electromagnetic characteristics, mathematical equations and mechanical motion equations of the DS-SRM drive system. The paper proposes multi-mode operations (inner-stator excitation mode, outer-stator excitation mode and double-stator excitation mode) based on motor working regions. It also conducts simulation and experimental results to verify the effectiveness of the proposed multi-mode operations strategies and control schemes.FindingsThere is almost no electromagnetic coupling between the inner and outer stators due to the specially designed rotor structure and optimized windings polarity configuration. Analysis of flux linkage distributions and torque characteristics verified the independence of inner and outer stators. Proposal of multi-mode operations and corresponding control rules achieved the smooth switching between different modes.Originality/valueThe paper introduced the DS-SRM for EVs and proposed multi-mode operations, along with control rules, to optimize its performance. The specially designed rotor structure, optimized winding polarity configuration, and the proposed multi-mode operations contribute to the originality of the research.

Analysis of low saliency ratio and torque characteristics of the fractional slot concentrated winding surface mounted motors

In recent years, fractional slot concentrated winding permanent magnet synchronous motors (FSCW PMSMs) have become a hotspot in the research field. Due to the unique inductance characteristics of the FSCW PMSM, a fast and accurate calculation of the d/q-axis inductance and saliency ratio is necessary. In this paper, a method is proposed to calculate the d/q-axis reactance of the FSCW SPMSM, which constructs the equivalent magnetic circuit model of the d/q-axis armature reaction flux separately, and the saliency ratio characteristics of the FSCW SPMSM were demonstrated. In addition, to meet the high requirements of the modern industries, especially in servo systems, accurate consideration of the effect of stator resistance on torque and electromagnetic performance is important and more applicable. According to the relationship between the vector parameter, the explicit expression of the d/q-axis currents that consider the stator resistance is obtained, and the prediction of load angle at maximum electromagnetic torque is achieved. Then, combined with the finite element method, the influence mechanism of stator resistance on the motor steady-state performance is revealed. Finally, the experimental data are compared with the calculation data, and the correctness of the models and analysis was verified.

Torque Disturbance Compensation Method Based on Adaptive Fourier-Transform for Permanent Magnet Compressor Drives

The large fluctuating torque disturbance of the single-rotor permanent magnet compressor has a significant impact on the drive system. An adaptive Fourier-transform-based torque disturbance compensation method is proposed to improve the control performance in this article. Based on the analysis of compressor load torque characteristics, a self-adjusting strategy is proposed to reduce the compensation error of the traditional open-loop Fourier-transform scheme. The compensation current is adaptively generated by adopting an indirect iterative learning mechanism that can obtain the multifrequency torque disturbances information in real-time. The proposed method does not require the accurate compressor parameters and the discrimination of harmonic disturbances, which has satisfactory suppression ability for the multifrequency torque disturbance. The convergence and parameter sensitivity of the proposed method are analyzed theoretically. The effectiveness of this method is verified by experiments on a 1.5-kW permanent magnet compressor drive platform.

The Design and Magnetic Field Analysis of a Double Rotor Permanent Magnet Braking Device

During long-term continuous braking, high-intensity braking, or frequent braking, the temperature of the brake disc or brake drum will increase significantly, resulting in a decrease in the friction coefficient, the aggravation of the wear degree, and the dangerous heat recession of partial or even total loss of braking efficiency. This paper focuses on an innovative double rotor permanent magnet braking device, which is located on the inner side of the wheel hub, to improve the heat decay resistance of the friction braking device. The structure and principle of the double rotor permanent magnet braking device were given, and its main structural parameters were designed, calculated, and optimized. The geometric model and finite element model of the double rotor permanent magnet braking device were established. The static and transient magnetic field analysis and the braking torque characteristic analysis of the double rotor permanent magnet braking device were carried out by using Maxwell electromagnetic analysis software. The results show that the magnetic flux density in the working area of the double rotor permanent magnet braking device increases with the increase in rotation speed, the braking torque changes with the change of rotation speed, and the maximum braking torque occurs in the low-speed area, which is consistent with the theoretical calculation results. This provides a theoretical basis for the follow-up prototype test of the double rotor permanent magnet braking device.

Multi-Objective-Layered Optimization of a Magnetic Planetary Gear for Hybrid Powertrain

In this article, an objective-layered optimization strategy is proposed and investigated for the magnetic planetary gear (MPG). The key and novelty are to comprehensively consider the sensitive relationships between objective and objective, as well as objective and parameter. From this, the sensitivity analysis method is utilized purposely. According to the result of sensitivity analysis, the optimization objectives are classified into two groups, thus the optimization process is divided into two layers. And, it is noted that the multi-objective genetic algorithm (MOGA) and double-side PM shaping method are respectively utilized in the two layers. In addition, the harmonic analysis of airgap flux density, cogging torque, and steady torque characteristics of MPG are also investigated in detail. Finally, a prototype machine and its hybrid system are built and tested. Both the theoretical analysis and experimental results verify the effectiveness of the proposed optimization strategy and studied MPG.

Electromagnetic Torque Characteristics Analysis of Nuclear Half-Speed Turbine Generator with Stator Winding Inter-Turn Short Circuit Fault

To research the variation characteristics and influence factors of air gap magnetic field and electromagnetic torque of nuclear power half-speed turbine generator with stator winding inter-turn short circuit, the two-dimensional transient electromagnetic field of generator-external circuit-grid coupling mathematical model is established by field-circuit-network coupling method. Taking the national laboratory’s generator as an example, and comparing the simulation results of the inter-turn short circuit of the armature winding with experimental data, the correctness of the model is validated. On this basis, the simulation model of a 1407MVA nuclear power half-speed turbine generator is built. Then the stator winding inter-turn short circuit fault is simulated when the generator is connected to the grid with rated load. The characteristics of air gap flux density and electromagnetic torque are obtained before and after fault, as well as, the relationship between their each component and the fault degree is obtained. At the same time, the variation law of air gap flux density and electromagnetic torque is obtained when the relative position between fault winding and magnetic pole changes. The theoretical reference for fault diagnosis and localization using harmonic electromagnetic torque after fault is provided.

Torque Characteristics Analysis of a Magnetorheological Brake with Double Brake Disc

Magnetorheological (MR) brake is a sort of electromagnetic brake that uses the controllable output characteristics of MR fluid for braking. In this paper, an MR brake with a double brake disc was developed to improve the braking performance of conventional MR brakes. The effective damping gaps were increased from the traditional two sections to four sections by increasing the single brake disc of the conventional MR brake to a double brake disc. By reasonably arranging the non-magnetic sleeve inside the MR brake, the magnetic flux lines were better guided to the effective damping gaps, which increased the utilization rate of the magnetic field, effectively enhanced the braking performance, and also reduced the braking power consumption. The structure and working principle of the MR brake with double brake disc were discussed. The magnetic field of the proposed MR brake was analyzed by ANSYS software, and the theoretical result of braking performance was obtained by combining the established mechanical model. The braking performance test rig was setup to investigate the torque performance of the MR brake. The experimental results show that the maximum braking torque is 18.01 N·m at the applied current of 2.0 A and the rotational speed of 400 r·min−1, and the simulation values are basically verified. In addition, the results indicate that the constant torque characteristic of the MR brake is relatively stable, and the torque is almost unaffected by the changes of rotational speed. The results can provide some guidance for the structural design and optimization of the MR actuators.

Torque characteristics analysis of dual-airgap spoke-type permanent-magnet Vernier machine considering pole ratio effect

The ratio between rotor poles and stator winding poles plays a deciding role in the performance of Vernier machines. Therefore, it is very important to analyze the effect of pole ratio on the electromagnetic torque performance of permanent-magnet Vernier machine. Dual-airgap spoke-type permanent-magnet Vernier machines (PMVMs) are becoming popular due to their low speed and high torque characteristics in the direct drive applications. This paper presents the effect of pole ratio on the performance of dual-airgap spoke-type PMVM. The performance parameters such as torque ripple, average torque, torque density and efficiency are analyzed by the variation of design parameters such as stator and rotor pole numbers and winding pole numbers, while keeping the same outer dimensions, similar magnet volumes and same airgap lengths in all the models. The electromagnetic torque characteristics are analyzed with the variation of pole ratios until the model reaches the maximum torque performance at a specific combination of rotor and stator poles. 2D-finite element method is used to analyze the performance of the model and verify the effect of pole ratio on the torque performance of dual-airgap spoke-type PMVM.

Analysis of Peak Electromagnetic Torque Characteristics for Superconducting DC Induction Heaters

The efficiency of novel superconducting direct current (DC) induction heaters can be up to 80-90%. This is much higher than the 40-50% of conventional alternating current induction heaters. Induction heaters are used to preheat aluminum billets in extrusion pressing. Such devices use a driving motor to rotate the billet. A peak in the electromagnetic torque appears at low rotation speeds (of the motor). Therefore, this peak electromagnetic torque is of particular interest when designing the driving system, which is one of the main challenges for megawatt-class superconducting DC induction heaters. In this paper, the peak electromagnetic torque characteristics of different sized billets were analyzed. A numerical 3D finite element method model was built to analyze the peak electromagnetic torque and resistive heating power behavior of aluminum billets. The results obtained from simulations and experiments match well. The effect of the following five relative parameters, on electromagnetic torque and resistive heating power, were studied: billet diameter, billet length, magnetic flux density, billet material, and electrical conductivity. The peak electromagnetic torque increases nonlinearly with increasing billet diameter, up to 640 mm. The time elapsed between the peak to stable torque decreases nonlinearly with increasing magnetic flux density. The effects of billet material (copper, titanium alloy and stainless steel) on torque were analyzed and compared. These results are likely to guide more cost-effective and practical designs for the billet driving system of superconducting DC induction heaters.

Lead-lag angles – torque characteristic analysis for turning control of butterfly-style flapping robot

Lead-lag angles – torque characteristic analysis for turning control of butterfly-style flapping robot

Torque Characteristic Analysis and Measurement of Magnetic Rack–Pinion Gear Based on Analytical Method

This paper analyzes the torque characteristics of a magnetic rack-and-pinion gear using an analytical method based on the spatial harmonic method. We obtain the magnetic field distribution due to the permanent magnets and derive the magnetic torque from the magnetic field using the Maxwell stress tensor. The analytical results are extensively validated by comparing with finite element analysis results. Finally, we obtain an accurate analytical solution to reduce the analysis time and experimentally verify this solution by applying it to a newly manufactured rack–pinion gear model.

Analysis of Torque Characteristics according to Non-uniform Air Gaps of Coaxial Magnetic Gear

Recently, studies on magnetic gears have been actively conducted. Magnetic gears can replace mechanical gears as they can perform noncontact power transfer, thereby minimizing loss and damage from friction. A magnetic gear has two rotors with different numbers of poles because of its structural characteristics. For a rotor with a relatively lower number of poles, large torque ripples occur owing to the increase in the permeance variation within the air gaps. Other electric equipment studies conducted thus far have primarily changed the shape of iron core to reduce torque ripples. However, since the magnetic gear has two air gaps, it is necessary to identify the relationship between the two gaps and the ripple before changing the shape of the iron core. In this paper, factors that affect torque ripple are classified and analyzed by examining the magnetic flux density of two air gaps, to propose an air gap structure that benefits the design of magnetic gears.

Analysis of Torque Characteristics of Parallel Hybrid Excitation Machine Drives With Sinusoidal and Rectangular Current Excitations

The parallel hybrid excitation machine (PHEM) consists of axial parallel permanent magnet machine part and doubly salient electromagnetic machine part. The three-phase armature windings of two parts are connected in series. Based on the waveforms of back electromotive force, both sinusoidal and rectangular current excitations can be adopted in PHEM. The torque characteristics of PHEM drives with ideal sinusoidal and ideal rectangular current excitations are analyzed. The average torque versus armature current in brushless ac (BLAC) and brushless dc drives are comparatively analyzed. Furthermore, the torque and torque ripple versus current angle in some typical armature currents are investigated. Moreover, the speed and torque waveforms are given under the vector control and the current pulsewidth modulation control scheme. Finally, the experimental data of the target PHEM agree well with the simulation results. It is shown that in BLAC drives, the PHEM exhibits higher torque density with lower torque ripple.

Torque modeling and characteristic analysis of electromagnetic piezoelectric hybrid-driven 3-degree-of-freedom motor

The electromagnetic piezoelectric hybrid-driven 3-degree-of-freedom motor is a new multi-degree-of-freedom motor. To further analyze the torque characteristics of the electromagnetic piezoelectric hybrid-drive 3-degree-of-freedom motor. First, the principle and basic structure of the hybrid-drive motor are introduced, and the displacement and pressure distribution of the stator–rotor contact surface are obtained by analytical method. Based on this, the torque model of the piezoelectric stator-drive motor is obtained. Then, the air-gap magnetic field model of the permanent magnet rotor is obtained by analytical method, and the electromagnetic stator-torque model is obtained. Finally, the torque model of the electromagnetic piezoelectric hybrid-drive 3-degree-of-freedom motor is established by vector synthesis. The effects of piezoelectric stator mounting position angle, stator–rotor contact materials, and preload on motor torque are analyzed by simulation. The advantages of electromagnetic piezoelectric hybrid drive are analyzed, and the rationality of the model is preliminarily verified. It lays the foundation for further optimization design and performance improvement of electromagnetic piezoelectric hybrid-drive 3-degree-of-freedom motor.

Measurement and Torque Calculation of Magnetic Spur Gear Based on Quasi 3-D Analytical Method

This paper presents the torque characteristics analysis and torque measurement of a magnetic spur gear with a three-segment Halbach array based on the Quasi Three-Dimension (3-D) Analytical Method. It analyzes a magnetic spur gear that uses a Halbach array by employing an analytical method for torque calculation. In the analytical method, from the magnetic vector potential and a coordinate system conversion, analytical solutions are obtained for magnetic fields produced by source magnets. By using the derived magnetic field solutions, an analytical solution is obtained for the external magnetic flux density. The drive magnet is next reduced to the equivalent current densities, and the torque is computed from these currents in the external magnetic field, which is obtained from the second process. Finally, the leakage flux in the z-direction occurring in the magnetic gear is considered using the 3-D analytical method. Thus, an analytical result can be obtained. These results are validated by comparison with the finite element method.

Torque and thermal characteristics analysis of a fluid damping based multi-degree-of-freedom motor

This paper presents a novel fluid damping based hybrid drive multi-degrees-of-freedom permanent magnet motor. The structure and working principle of the motor is introduced. The torque features are analyzed using both finite element method and analytical method. Based on the thermal safety and thermal stability in the practical design of this motor, the thermal characteristics with heat sources are calculated and simulated. By using FEA software to model the heating status when the motor works under rated operation and high overload current conditions, the temperature contours within the motor structure can be obtained. The fluid and modal analysis are also conducted with numerical simulation. The research results validate the reasonable structure design of this motor and can be the reference of structure optimization and performance improvement indicators for this kind of motors.

Torque characteristic analysis and measurement of axial flux-type non-contact permanent magnet device with Halbach array based on 3D analytical method

This paper addresses the torque characteristic analysis of an axial flux-type non-contact permanent magnet device with a Halbach magnet array using a 3D analytical method based on transfer relations. We obtain the magnetic field distribution due to the permanent magnet. The magnetic torque is derived from the magnetic field using a Maxwell stress tensor. The analytical results are validated extensively by comparison with 3D finite element analysis. Therefore, we derive an accurate analytical solution to reduce the analysis time, and we present an experimental verification using a manufactured model.

Torque Characteristic Analysis of an IM/PM Hybrid Motor by Using Finite Element Method

This paper presents torque characteristic analysis of synchronous induction motors called “IM/PM hybrid motors” by using the two-dimensional finite element method taking terminal voltage into account. The slip characteristics are analyzed by using multi-meshes corresponding to each rotor position, because the transient numerical analysis is quite difficult due to slip even two-dimensional analysis. There are many researches on IM/PM hybrid motors, however the torque characteristics when they are operating as an induction motor have not yet examined sufficiently. In this paper, we tried to explore how to improve the torque characteristics even operating as an induction motor by incorporating the embedded permanent magnets. The results show that the arrangement of the permanent magnets is very important to improve whole torque characteristics.

Study of the Spinning Mechanism Resulting from Permanent Magnet Linear Actuation

This paper describes an analysis of torque characteristics of a noncontact spinning system using linearly actuated magnets. This noncontact spinning system spins the suspended object (here is an iron ball) without contact by the remanent magnetization and the linear movement of four permanent magnets. In this paper, the remanent magnetization point is modeled, and the rotational torque of this mechanism is calculated by IEM (Integral Element Method) analysis. The rotational torque is also measured using a measurement device with strain gauges. According to the IEM analysis results and the experimental results, the rotational torque characteristics of the noncontact spinning system are discussed.

Winding Function 이론을 이용한 동기형 릴럭턴스 전동기의 토크 특성 해석

In this paper, torque characteristics analysis of Synchronous Reluctance Motor with the cylindrical rotor type by winding function theory(WFT) is described. The stator is same as one of the induction motor. From the d-axis, q-axis flux density distribution, to calculate self and mutual inductances needed to calculate the torque of the machine by using winding function theory the new equivalent geometry of rotor was proposed. D-axis, q-axis flux densities, self inductance and torque characteristics were obtained. From the comparison with results of finite element analysis the proposed method was verified.