Magnetic Gear Research Articles

3-D Magnetic Field Mathematical Model Considering the Eccentricity and Inclination of Magnetic Gears

3-D Magnetic Field Mathematical Model Considering the Eccentricity and Inclination of Magnetic Gears

Electromagnetic performance analysis of a novel radial compound differential field-modulated magnetic gears

Purpose The purpose of this study is to propose a new magnetic gearing device and the proposed transmission model can be applied in the field of wind power and wave energy generation gearboxes. Design/methodology/approach A novel radial differential field-modulated two-stage magnetic gear is introduced, using a unique radial differential linkage to integrate two single-stage magnetic gears. This design incorporates a magnetic isolation ring to enhance transmission efficiency by minimizing magnetic interference and preventing power circulation. The two-stage modulating ring rotor operates synchronously via a connecting bridge, ensuring system stability and efficiency. This configuration not only boosts the gear ratio but also maintains a compact structure, improving power density and efficiency. Leveraging the magnetic field modulation and differential transmission, a finite element model of this gear is developed and its electromagnetic performance is analyzed. Findings The torque density of the new radial differential field-modulated two-stage magnetic gear has increased by 44.97% compared to the traditional tandem two-stage magnetic gear. It achieves a high transmission ratio of 64 and maintains comparable power density, indicating strong torque transfer capabilities suitable for low-speed, high-torque applications. During steady-state operation, the torque pulsation difference between the two stages is minimal, ensuring stable working torque. Social implications This research not only propels the forefront of magnetic gear technology through heightened efficiency and streamlined design but also bears profound societal significance in fostering sustainable energy paradigms. By facilitating superior energy conversion efficiencies in wind turbines and wave energy converters, it plays a pivotal role in mitigating carbon emissions and accelerating the global pivot towards cleaner, renewable energy landscapes. Originality/value A magnetic gear transmission device is proposed, which can achieve high power density and large transmission ratio at the same time, and this study provides a useful reference for the design optimization of new high-performance multistage magnetic gears.

Innovative Magnetic Gear Design Incorporating Electromagnetic Coils for Multiple Gear Ratios

In this study, a novel magnetic gear design is introduced. Unlike conventional magnetic gears that can only achieve a single gear ratio using permanent magnetic poles, the proposed design incorporates electromagnetic coils that can adapt to various control strategies, resulting in a multiple gear ratio for the same machine design. We selected a gear system with five gear ratios to validate the new design. The performance of the proposed design was compared with that of the conventional magnetic gear. While permanent magnet poles offer high torque transmission with a small volume, they cannot provide different gear ratios for the same configuration. Therefore, this work suggests using a single-gear machine based on a fixed number of electromagnetic coils to achieve different gear ratios. This research outlines the design steps, simulation process, and detailed analysis. The results demonstrate the effectiveness of the proposed design strategy, which can be potentially applied to wind turbines, transportation, and other scenarios with comparable success.

Fast Analysis and Optimization of a Magnetic Gear Based on Subdomain Modeling

Fast Analysis and Optimization of a Magnetic Gear Based on Subdomain Modeling

Experimental and Numerical Test of Radial Internal Magnetic Spur Gear

Experimental and Numerical Test of Radial Internal Magnetic Spur Gear

A Comprehensive Review of Concentric Magnetic Gears

A Comprehensive Review of Concentric Magnetic Gears

Chaotic behaviour in the dynamical response of coaxial magnetic gears during acceleration

Slippage during acceleration has been a significant issue in coaxial magnetic and has been thoroughly investigated in the recent years. Depending on the applied outer load it is important to know the maximum acceleration that can be induced so that the system will not diverge. In the present work a non-dimensional analysis has been conducted in order to develop a stability criterion for the maximum acceleration that can be applied to the system as a function of the outer load. A closed-form relation for the period of the oscillations of the system that will be caused by the acceleration, has also been derived. Furthermore, the case of acceleration with ripple has been investigated. It was demonstrated that during acceleration with ripple under constant applied outer load, the system showcases a chaotic behaviour similar to the driven pendulum. In particular, a thorough analysis on the frequency of the ripple has been conducted. It was observed that when the ripple frequency was slightly lower than the frequency of the oscillation under steady acceleration, the system could potentially diverge even if the acceleration of the system was lower than the critical value. With the present work, a detailed non-dimensional model has been derived that could be a useful tool for determining the stability of coaxial magnetic gears without the requirement of numerical solution of the governing equations. In addition, some interesting observations are made regarding the chaotic behaviour of the dynamical response of coaxial magnetic gears during acceleration with ripple.

Multi-objective optimization and analysis of divided-layer varying-network magnetic circuit based axial field flux-switching magnetic gear composite motors

Multi-objective optimization and analysis of divided-layer varying-network magnetic circuit based axial field flux-switching magnetic gear composite motors

Numerical Modeling and Optimization of a Quasi-Resonant Inverter-Based Induction Heating Process of a Magnetic Gear

Numerical Modeling and Optimization of a Quasi-Resonant Inverter-Based Induction Heating Process of a Magnetic Gear

Optimum design of a coaxial magnetic gear integrated with a permanent magnet synchronous generator of a wind turbine based on the pelican optimization algorithm

This paper presents an optimum design of a coaxial magnetic gear (CMG) Integrated with a Permanent Magnet Synchronous Generator (PMSG) of a wind turbine using a pelican optimization algorithm (POA) launched in 2022. In order to evaluate the proposed system design based on POA, the well-known Particle Swarm Optimization (PSO) is implemented for the same CMG under the same conditions and constraints. Also, a Taguchi-method-based sensitivity analysis for the key design variables is employed to determine their impact on the system’s performance. The optimization process for the CMG design based on POA and PSO is executed based on the 2-D Finite element analysis (FEA) using the Finite Element Method Magnetics (FEMM) program. The results obtained from the POA and PSO are compared and analyzed. The results underline that the optimum design for the CMG/PMSG integrated system based on POA achieves more torque/weight ratio and then more generated power and currents as compared to PSO. It is concluded that the proposed design based on POA gives a superior and efficient design with substantial stability and rapid convergence.

EV Motor System with Magnetic Gear Satisfying High Power Density and High Torque Density

EV Motor System with Magnetic Gear Satisfying High Power Density and High Torque Density

Design and experimental verification of hybrid excitation magnetic field modulation machine for electric vehicle propulsion

As one sort of flux modulation machine based on magnetic gear effect, field-modulated machine features with low speed large torque. A novel hybrid excitation field-modulated machine (HEFMM) is proposed by introducing the concept of hybrid excitation, the flux modulation poles (FMPs) and excitation winding of which are emplaced in stator teeth and the adjacent FMPs. It can be maintained wide speed range operation through the processes of flux-enhancing and flux-weakening with no increasing machine bulk, as well as the numbers of stator and rotor slot. The working principle of proposed machine is deeply studied, as well as basic electromagnetic characteristics are calculated by finite element method, including no-load magnetic flux linkage, no-load back electromotive force, cogging torque and output torque. In addition, the processes of flux-enhancing and flux-weakening are analyzed. Finally, one prototype with one kilowatt was built and its static characteristics were tested. The results show that the proposed HEFMM has the features of high torque density, small cogging torque and wide speed range, which is promising candidate for electric vehicle direct drive field.

Detailed Investigation of the Eddy Current and Core Losses in Coaxial Magnetic Gears through a Two-Dimensional Analytical Model

This work introduces a 2D model that calculates power losses in coaxial magnetic gears (CMGs). The eddy current losses of the magnets are computed analytically, whereas the core losses of the ferromagnetic segments are computed using an analytical–finite element hybrid model. The results were within 1.51% and 3.18% of those obtained from an FEA for the eddy current and core losses in the CMG for an indicative inner rotor speed of 2500 rpm. In addition, the significance of the circumferential magnet segmentation is demonstrated in the CMGs. Furthermore, a parametric investigation of the efficiency of the system for different applied external loads is carried out. Finally, a mesh sensitivity analysis is performed, along with the computation of the average power losses throughout one full period, resulting in an at least 80% reduction in computational costs with a negligible effect on accuracy. The developed model could be a valuable tool for the minimization of power losses in CMGs since it combines high accuracy with a low computational cost.

Theoretical and experimental comparison of gear systems: Planetary mechanical transmission and coaxial magnetic gear

Gear systems in today’s industry are one of the critical pillars providing power transformation and matching speed and torque to application requirements. Reliability, high efficiency, and low operating costs are desirable due to the prevalence of gearboxes. This paper provides a comparative analysis of selected mechanical and magnetic gears, using a specific example to point out the advantages and disadvantages of contactless power conversion. After determining the essence of the operation of the magnetic gear on the base model, two magnetic gear optimization cases are presented, testifying to the application potential. An analysis of the stress distribution in the area of the teeth of the mechanical gearbox and the most stressed element of the magnetic gear - the modulator, was carried out. The effects of temperature and load on losses were measured and simulated, and ultimately, the efficiency characteristics of the two gears were also compared.

Design of an Axial-Type Magnetic Gear with Auxiliary Flux-Enhancing Structure

In this paper, a new axial-type magnetic gear with an auxiliary flux-enhancing structure (AFS-AMG) is proposed. Compared to conventional AMGs, it has a higher torque density and higher permanent magnet (PM) utilization factor. Firstly, the design rules and operating principles of the proposed AFS-AMG are elaborated. Then, the mapping relation between the radial-type magnetic gears (RMGs) and AMGs are elucidated. Compared to its counterparts in RMGs, the AFS-AMG achieves a small size. Then, the geometrical parameters of the AFS-AMG are optimized to obtain better electromagnetic performance, where the torque density per volume and per PM volume is adopted as the evaluation standard. Finally, three different AMG topologies are constructed in finite element analysis (FEA) software for comparison. It is proven that the AFS-AMG has the largest torque density per volume and per PM volume.

An analytical fast field solver for surface permanent magnet co‐axial magnetic gears

AbstractA mathematical model of co‐axial magnetic gears is given for the prediction of magnetic field distribution and the magnetic forces. The modelling approach is based on the separation of variables method (SVM), Sturm–Liouville problem, and spectral analysis. This method is computationally more efficient and has the ability to account for finite permeability of magnetic saliency. An finite element method (FEM) validation is performed for a case study, and the results are observed to be almost matched. The computational time of the analytical model has been almost in the same order of that of the FEM for a specified rotor position (both in a matter of a second or less); however, when 100 number of rotor positions were accounted in the simulation, the computational time of FEM was increased to 82 s, while the computational complexity of SVM was almost unaffected.

Mathematical modeling of a magnetic gear for an autonomous wind turbine

Mathematical modeling of a magnetic gear for an autonomous wind turbine

Torque Calculation and Dynamical Response in Halbach Array Coaxial Magnetic Gears through a Novel Analytical 2D Model

Coaxial magnetic gears have piqued the interest of researchers due to their numerous benefits over mechanical gears. These include reduced noise and vibration, enhanced efficiency, lower maintenance costs, and improved backdrivability. However, their adoption in industry has been limited by drawbacks like lower torque density and slippage at high torque levels. This work presents an analytical 2D model to compute the magnetic potential in Halbach array coaxial magnetic gears for every rotational angle, geometry configuration, and magnet specifications. This model calculates the induced torques and torque ripple in both rotors using the Maxwell Stress Tensor. The results were confirmed through Finite Element Analysis (FEA). Unlike FEA, this analytical model directly produces harmonics values, leading to faster computational times as it avoids torque calculations at each time step. In a case study, a standard coaxial magnetic gear was compared to one with a Halbach array, revealing a 14.3% improvement in torque density and a minor reduction in harmonics that cause torque ripple. Additionally, a case study was conducted to examine slippage in both standard and Halbach array gears during transient operations. The Halbach array coaxial magnetic gear demonstrated a 13.5% lower transmission error than its standard counterpart.

Triboelectric–Electromagnetic Hybrid Energy Nanogenerator with Variable‐Frequency Effect Inspired by Magnetic Gears for Efficient Use of Low‐Speed Flow Energy

In the macrocontext of a low‐carbon and energy‐efficient economy, the rise of new energy vehicles is expected to replace traditional fuel vehicles. However, with the increasing number of new energy vehicles, the source of electricity for charging facilities faces new challenges. This study proposes a triboelectric–electromagnetic energy hybrid nanogenerator (VF‐TEMG) with a variable‐frequency effect inspired by an axial magnetic gear. The unit consists of one triboelectric nanogenerator (TENG) unit and two electromagnetic generator (EMG) units. The TENG unit employs a ternary dielectric structure to achieve kilovoltage output and reduce torque. Moreover, charging efficiency is enhanced using a mixture of high voltage from the TENG and EMG high current. Using the magnetic field modulation principle, the magnetic poles, which are produced by the low‐speed rotor permanent magnets, are modulated by a pole‐modulating piece into a magnetic pole harmonic equal to the number of pairs of high‐speed rotor permanent magnets. Consequently, when the low‐speed rotor starts to rotate, it drives the high‐speed rotor to rotate at high speed, thereby achieving variable‐frequency motion. This work establishes the theoretical and experimental basis for harvesting and effectively utilizing green energy based on frequency conversion.

Nonlinear control of coaxial double rotor magnetic gear based on high gain observer in wind turbine

AbstractThis paper proposes a nonlinear control law with a dynamic controller based on high gain observer (HGO) for a co‐axial double rotor magnetic gear (CADRMG) based on Halbach array used in wind turbines. The generalized canonical form (GCF) is used to normalize the nonlinear augmented system to achieve the dynamic control signal with a chain of integrator of system output. In addition, a tracking problem is defined to track high speed rotor (HSR) with respect to GCF. On the other hand, the HGO is used to estimate the error tracking at the expense of nonlinear terms. Furthermore, the nonlinear system observability of the augmented system is evaluated. A dynamic control law is used to solve the tracking problem based on HGO. This controller can eliminate the effect of load torque as a constant and unknown disturbance in the closed‐loop system. Moreover, the closed‐loop stability of the system under dynamic signal control is guaranteed. The system states estimation is calculated by recursive equations from tracking error estimations. Finally, numerical simulations are given to illustrate the theoretical results of proposed system.