Armature Reaction Research Articles

Core Loss Analysis of Axial Modular Flux Switching Permanent Magnet Machine Considering the Impact of No‐Magnetic Ring

This paper investigates the relationship between the distributions of the core loss and the flux density harmonic amplitude along the axial direction in an axial‐modular flux‐switching permanent‐magnet (AM‐FSPM) machine. The flux leakage in the no‐magnetic ring leads to an uneven distribution of flux density in the core due to the modular cooperation structure. Subsequently, variations in the fundamental flux density amplitudes in the PM field and the armature reaction field are obtained with changes in the thickness of the no‐magnetic ring. In addition, the impact of no‐magnetic ring thickness on machine torque and core loss is analyzed to determine the optimal thickness for the no‐magnetic ring. Finally, the validity of the theoretical analysis is confirmed by experimental validation. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Armature Reaction Analysis and Suppression of Voice Coil Actuator Based on an Improved Magnetic Equivalent Circuit Model

The high thrust density voice coil actuator (VCA) is a key component for the deployers to determine the CubeSats' separation velocity in orbit directly. To improve the VCA's thrust density and power consumption, it is essential to analyze the armature reaction under heavy current work conditions. This paper proposes a dynamic splitting method of the magnetic equivalent circuit (MEC) model for analyzing the armature reaction of the VCA. This MEC model can effectively reveal the interaction mechanism between the dynamic winding field and the permanent magnet (PM) field, which provides an approach to readily and quickly analyze the armature reaction. Based on the understanding of the mechanism, we found an effective way to suppress the armature reaction and propose a new VCA with double PM flux circuits. The electromagnetic performances of the new configuration are evaluated by comparing it with the conventional one. Both the theoretical and experimental results show that the new structure achieves lower magnetic saturation, lower armature reaction, and higher thrust density. A research prototype was constructed and experimentally tested to verify the theoretical results of the armature reaction, magnetic field, thrust, separation velocity, and other performances. The new VCA realizes a wide and accurate modulation of separation velocity for the CubeSats.

A modular IGBT power stack − based and open hardware framework for small wind turbines assessment

Wind energy technologies have emerged as the predominant renewable energy source within the framework of present-day electric power systems. Their design process, aligned with foundational theories, ought to be precision-engineered and systematized to fully maximize the potential of this energy source. This study presents a platform as solution designed and built to characterize and assess Small Wind Turbines (SWT), based on free software and open hardware. Additionally, the developed methodology step-by-step guide is disclosed. The characterization is based on the use of Permanent-Magnet Synchronous Generator (PMSG) as machine widely adopted in Wind Energy Conversion System (WECS) less than 100 kW. The core theoretical background is detailed to confirm the accuracy of the parameters procedures acquisitions. Poles number, machine design constant, armature reactance, synchronous reactance, and power-dynamic characteristic related to WECS are determined. This laboratory set-up is composed of variable industrial fan, rectifier, boost converter and a bidirectional Direct-Current (DC) source as a battery emulator. All components have been assembled within the laboratory environment using commercially available elements. Low implementation cost and versatile methods determine the real input in practice of this platform. To validate the effectiveness for any SWT, a real one is tested, and every parameter proposed is calculated.

Nonlinear Analytical Solution in Axial Flux Permanent Magnet Machines Using Scalar Potential

Analytical model (AM) has significant value on early design stage for electric machines, in terms of both time and accuracy. AM can be developed based on vector or scalar potential, but all AMs for armature reaction are using the vector potential, and it is a difficult matter to model armature reaction by scalar potential. This is the gap that the work here proposed aims to fill. We, for the first time, report the load magnetic field prediction by using magnetic scalar potential. Also, the proposed nonlinear AM is developed for the surface mounted permanent magnet machine. The proposed model is development based on the two-dimensional harmonic subdomain approach by solving the Maxwell's equations. The magnetic sources, viz., the armature reaction is regarded as line current and solved at the connection boundaries. The comprehensive derivations and calculation algorithm are explained in detail. Moreover, the analytical model is developed for an axial flux PM machine, both finite element model and experiment are verified the correctness of proposed model, and good agreement is achieved. Moreover, a slightly modification can also be applied to the radial flux PM machines.

Primary component segmental design to suppress the normal force ripple for the permanent magnet linear synchronous motor

AbstractThere is not only thrust but also normal force between the primary and secondary components for the single‐side flat plate permanent magnet linear synchronous motor (PMLSM). The normal force will fluctuate periodically, which will cause friction perturbation and finally affect the positioning accuracy of linear feed system. For the single‐side flat plate PMLSM, the variation law of normal force ripple under the coupling effect of multiple effects is studied, and the method of primary component segmental design to suppress it is proposed. Firstly, the influence of the cogging effect, the end effect and the armature reaction on the normal force ripple is analysed. Meanwhile the mathematical model of normal force ripple is established. Secondly, the PMLSM with segmental primary component is introduced and its suppression mechanism to the normal force ripple is expounded. On this basis, a scheme combining the non‐integer pole slot matching with the primary component segmental design is proposed to further suppress the normal force ripple. Finally, an 18‐slot 96/5‐pole prototype is taken as an example to carry out the finite element simulation and experimental test, of which the results verify the research theory in this paper.

Magnetic Field Distortion Analysis and Suppression for the Minimum Unit Winding Segmented Moving-Magnet Linear Motor

Segmented power supply is frequently utilized for long-stroke moving-magnet linear synchronous motors to lessen the issue of large loss and heating brought on by long-stroke power supply. However, the driving mode of partial excitation in segmented power supply brings some problems, such as unbalanced parameters of three-phase, the transient inductance of winding changing with secondary position, and distortion of armature reaction magnetic field. This paper proposes a new topology with the minimum unit winding segmented to solve the problems of unbalanced inductance parameters and distortion of armature reaction magnetic field in winding segmented permanent magnet linear synchronous motors (WS-PMLSM). An analytical model of inductance distortion in the end coils of a moving-magnet PMLSM is established and compared with the non-end coil inductance to summarize the mechanism of inductance unbalance in WS-PMLSM. Based on the model of winding transient inductance changing with secondary position, the changing law of transient inductance is expounded. An analytical method of the air gap magnetic field based on virtual winding is proposed, and the formation mechanism of magnetic field distortion caused by partial excitation is revealed. Aiming at the topology of the minimum unit winding segmented moving-magnet PMLSM, an optimized drive strategy of n+3 is proposed.

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.

The effect of excitation current on radial electromagnetic force wave of tangential magnetizing parallel structure hybrid excitation synchronous motor

To study the influence of the magnitude of the excitation current on the radial electromagnetic force wave of the tangential magnetizing parallel structure hybrid excitation synchronous motor (TMPS-HESM) under different working conditions. Firstly, the basic structure of the motor and the rotor magnetic circuit model is introduced. Secondly, considering the influence of excitation current, the Maxwell stress tensor method is used to analyze the radial electromagnetic force wave of the motor and the source, frequency and order of the radial electromagnetic force wave that has a great influence on the electromagnetic vibration of the motor are qualitatively obtained. Then, the three-dimensional finite element method is used to calculate the variation law of the radial electromagnetic force wave when different excitation currents are applied under no-load and load conditions, revealing that the DC excitation will increase the amplitude of the radial electromagnetic force wave of a specific order. Meanwhile, the influence of load torque variation on the radial electromagnetic force wave is discussed, and it is found that the (2f, 8) and (6f, 24) order electromagnetic force waves are greatly affected by the armature reaction. The work provides a theoretical basis for further suppressing the electromagnetic vibration of this type of hybrid excitation motor.

The influence of electromagnetic field models on the damper winding loss and heat calculation results of tubular hydro‐generator

AbstractThis study investigates the effect of electromagnetic field models on tubular hydro‐generator damper winding losses and heat calculations using an on‐site 36‐MW such generator as an example. Sinusoidal steady‐state and transient‐motion electromagnetic field models were established to analyze damper winding losses and heat. Results indicate that, despite exhibiting a substantially higher computational efficiency than the transient‐motion electromagnetic field time‐stepping FE model, the sinusoidal steady‐state electromagnetic field FE model does not comprehensively and reasonably consider several key factors, such as tooth and slot effects, the main magnetic field, and the armature reaction. Consequently, the magnetic field, damper bar loss, and heat derived from this model exhibit considerable deviations from the on‐site generator observations. In comparison, the transient‐motion electromagnetic field time‐stepping FE model, owing to its ability to consider these influencing factors, provides more comprehensive and reasonable results.

Comparison and research on load characteristics of PM in different permanent magnet synchronous machines

PM enable PMSMs to have higher torque-density and power-density, however the machine performance is closely related to its load characteristics. When the armature excitation does not match the load characteristics of the PM and machine, it can lead to demagnetization and performance degradation. By comparing and studying the IPMSM’s and SPMSM’s load characteristics, a more reasonable machine topology of components such as PM can be obtained, and high-performance machines can be designed more efficiently. Based on the material characteristics of the PM, the armature reaction law of different machines and the demagnetization law of the PM at different current angles were analyzed. There are different magnetic field distribution patterns in IPMSM and SPMSM, and their different load characteristics are compared to study the methods for improving the anti-demagnetization ability of PMs based on different machine structures.

Research on Torque Ripple and Influencing Factors of Hydro-Generator

Background: The safe and stable operation of large-capacity hydro-generators is of great significance to the power grid. However, due to the armature reaction and the stator slots of the hydroelectric generator, the torque ripple of the generator is usually large. Long time running under the condition of large torque ripple will cause damage to the generator components and even threaten the safety of the power grid. Objective: To study the factors affecting the torque ripple of the hydro-generator and reduce the torque ripple. Methods: A 24 MW bulb tubular hydro generator is taken as an example, a two-dimensional transient electromagnetic field model was established, and the correctness of the model was verified by experiments. The causes of armature reaction and cogging effect on motor torque are analyzed. The effects of these two factors on torque ripple are studied respectively. The torque ripple under different working conditions is calculated, and the main factors causing and increasing torque ripple during normal operation of hydro generator are determined. Results: The torque ripple increases approximately linearly with the increase of the 7th and 11th harmonic contents, while it increases nonlinearly with the increase of the 5th harmonic contents. When the excitation current increases from 720 A to 960 A, the torque ripple is increased by 11.4kN•m. In addition, when the excitation current increases from 720A to 840A (Rated excitation current of the generator is 840A), the torque ripple increases greatly, the torque ripple increases by 6.6kN•m. When the excitation current exceeds the rated excitation current, due to the influence of magnetic saturation, the increasing extent of torque ripple gradually decreases. When the excitation current increases from 840A to 960A, the torque ripple increases only by 4.8kN•m. Conclusion: Due to the armature reaction, the harmonic magnetic potential will be generated in the generator, which will affect its torque ripple. The torque ripple of the generator will increase obviously with the increase of harmonic content. When the generator is in no-load operation, the slot effect is the main cause of the torque ripple. In the actual operation of the generator, it usually needs to adjust the excitation current to make the generator meet the requirements of various working conditions.

Analysis of Stator-Slot and Rotor-Pole Combinations of Axial Modular-Flux Reversal Permanent Magnet Machine

This paper investigates the influence of stator-slot and rotor-pole combinations on torque performances in axial modular-flux reversal permanent magnet (AM-FRPM) machines. Based on the slot-conductor back-EMF star vector theory, the winding factors of all stator-slot and rotor-pole combinations are improved by adopting toroidal windings. In addition, based on a magnetomotive-force and permeance model, the candidates of stator-slot and rotor-pole combinations with higher torque capacity can be determined by analyzing the harmonic combinations between the PM and armature reaction field. Besides, the cogging torque is suppressed by selecting the corresponding angle between rotor modules for different stator- slot and rotor-pole combinations. Finally, an electromagnetic performance comparison between a conventional FRPM machine and three AM-FRPM machines candidates with attractive torque performances is conducted, and the experiments are constructed to verify the theoretical analysis.

Series Motor Four Quadrants Drive DC Chopper Controllers Noise Cancellation

DC Series motor armature reaction causes EMI. EMI generates noise signals that affect feedback sensor readings, feedback controller function, and controller halting. This paper discusses software discrete filter and RLC hardware filter noise cancellation and filtering. The filter eliminates EMI-induced IGBT gate firing noise. Matlab/Simulink tests the filter circuit and digital filter control method, confirming software and hardware filter implementation.

Study on enhanced performance of CuFe alloy's eddy current damping and its advantages in multi-mode vibration control of stay-cable

This study presents an innovative solution to address the performance degradation of eddy current dampers (ECD) at high speeds. It replaces the traditional copper conductor with a magnetically and electrically conductive CuFe alloy. The damping force equation for this CuFe alloy-based ECD (CuFe-ECD) is derived and validated through rotor experiments and a simplified finite element model. Results confirm that CuFe alloy enhances damping performance, with CuFe20 exhibiting outstanding quasi-bilinear characteristics, particularly at higher speeds. CuFe10, CuFe15, and CuFe30 also demonstrate similar behavior. The study explores the impact of CuFe alloy properties (conductivity, permeability, and thickness) on the bilinear damping curve. CuFe alloys notably reduce magnetic reluctance, especially in thicker conductors, mitigating skin effect and armature reaction in the electromagnetic field. Finally, the CuFe-ECD is utilized for multi-mode vibration control using the long cable of the Sutong Bridge. The results indicate that the modal damping ratios of modes 1st-20th can reach 5‰, which is superior to other schemes. In high-order modes, the damping ratio of the 35th-40th modes still stabilizes at 3.72–3.90‰. It can be concluded that the bilinear damper has significant advantages in multi-mode vibration control: compared with the single linear damper scheme, it can improve the vibration reduction effect of multi-mode control, and compared with the dual linear damper scheme, it can reduce the number of dampers and achieve better economic benefits.

Incorporating the coupled effects of slot opening, armature reaction and saturation in the model of the airgap flux density distribution of permanent magnet synchronous machines

AbstractA new analytic model for calculating of the air‐gap flux density (AGFD) of surface‐mounted permanent magnet synchronous machines (SMPMSMs) is presented. This proposed model is capable to taking into account the effects of magnetic saturation, armature reaction and stator slots opening. Furthermore, the real form of air‐gap distribution and spatial distribution of flux density of the PM poles are considered. The armature reaction effect is modeled using phasor diagram analysis of the motor as a function of the load torque, the armature current amplitude, power factor and the inverse air gap length. Also, saturation phenomenon predicted using the new non‐linear proposed function in connection with the armature reaction effects and the properties of the lamination material. It is shown that the proposed model capable to predicting acceptably the air gap flux density waveform of the SMPMSMs at lagging and leading power factors and with the load torque variation. The presented analytical approach is verified by the two‐dimensional finite‐element analysis (FEA) results.

Armature Reaction Analysis and Performance Optimization of Hybrid Excitation Starter Generator for Electric Vehicle Range Extender

The armature reaction of the hybrid excitation starter generator (HESG) under load conditions will affect the distribution of the main magnetic field and the output performance. However, using the conventional field-circuit combination method to study the armature reaction has the problem of low accuracy and inaccurate influencing factors. Therefore, this paper proposed a graphical method to analyze the armature reaction and a new type of HESG with a combined-pole permanent magnet (PM) rotor and claw-pole electromagnetic rotor. The analytical formula of the voltage regulation rate under the armature reaction was derived using the graphical method. The main influencing parameters of the armature reaction magnetic field (ARMF) were analyzed, and the overall output performance was analyzed using finite element software. On this basis, comparison analyses before and after optimization and the prototype test were carried out. The results show that the direct-axis armature reaction reactance, quadrature-axis armature reaction reactance, and voltage regulation rate of the optimized HESG were significantly reduced, the output voltage range of the whole machine was wide, and the voltage regulation performance was good.

Comprehensive Armature Reaction Modeling and Flux Weakening Optimization of a Surface Permanent Magnet Vernier Motor

Surface permanent magnet vernier motors (SPMVMs) possess the potential for direct-drive applications due to the feature of high torque density. This paper presents a deep investigation into the armature reaction modeling and a semi-analytical optimization framework considering the constant power speed range (CPSR) in the flux weakening region for the SPMVM. The new armature reaction model can identify the armature air gap flux density of each harmonic component and armature flux linkage accurately, by conducting harmonics analysis, slot leakage flux computation and slotting effect evaluation, permitting to calculate the inductance. Then, the results from the armature reaction model and those obtained from finite element analysis (FEA) at the rated operating point together are applied to a comprehensive semi-analytical motor optimization framework developed for SPMVMs. The optimization framework is able to reflect the motor performance metrics over the entire speed range, with torque density, power factor and CPSR as objectives. Finally, a prototype designed according to the trade-offs of the optimization objectives is fabricated to confirm the validity of the armature reaction model and optimization framework.

Design and Analysis of Axial-Modular Flux-Switching Permanent Magnet Machine

This paper proposes a novel axial-modular-flux switching permanent magnet (AM-FSPM) machine, which contains two modular parts and integrated toroidal windings. After investigating the operation principle of the AM-FSPM machine, the modular PM field complementarity and integrated armature reaction field complementarity principles of two axial modular parts are revealed based on the field modulation theory. Then, a comprehensive comparison of the modulation principle between the AM-FSPM and conventional FSPM machines is conducted from perspectives of PM field, armature reaction field, cogging torque and electromagnetic torque production mechanism. It can be found that the modulation principle reveals the difference between the operation principles of two flux switching machines. In addition, the cogging torque reduction capability of AM-FSPM machine is investigated, which provides guidance on stator-slot and rotor-pole combinations in the design stage of industrial applications. Moreover, compared with conventional FSPM machines, the AM-FSPM machine exhibits high torque capability and flux weakening capability, meanwhile maintains high efficiency at high speed. Further, its characteristics are verified by the experiments.

Reduction of quadrature armature reaction in salient-pole synchronous generator by rotor flux barrier

Reduction of quadrature armature reaction in salient-pole synchronous generator by rotor flux barrier

Potential Performance of Fully Superconducting Generators for Large Direct-Drive Wind Turbines

Fully superconducting generators (FSCGs) for wind turbine applications are usually synchronous machines. A high torque density should be obtained by increasing both the main field and the armature current loading. However, there are tendencies that the main field can be low but the armature current loading can be high, such as permanent magnet superconducting generators. Despite <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$J_\mathrm{{c}}(B,T)$</tex-math></inline-formula> characteristics and AC loss issues, simply using superconducting armature may not lead to a desired design result but deteriorate the performance with high armature reaction. This paper implements the vector-phasor diagram of non-salient synchronous generators for revealing the potential performance of only increasing the armature current loading. Three commonly used control strategies are compared. The results show that increasing the armature-field flux to a certain level will deteriorate the generator performance with all three control strategies. Comparatively, the voltage control for equaling EMF and voltage amplitudes provides the best overall performance: high torque production capability, high power factor, small power angle and a wide range of armature current loading. The results obtained from the vector-phasor diagrams are verified by finite element models with an FSCG design.