Search Results (9)

This paper proposes a high-efficiency design for an external rotor interior permanent magnet synchronous motor (IPMSM) that eliminates the magnetic leakage flux path. The conventional model based on an external rotor surface-mounted permanent magnet synchronous motor (SPMSM) is analyzed using a statistical method. Design directions are derived by comparing efficiencies at two major operating points with different motor characteristics. A V-shaped IPMSM is then proposed to increase the permanent magnet volume and reduce magnetic leakage. Design optimization is conducted using Gaussian process models (GPMs) constructed with a Latin hypercube design (LHD), and the optimal design is determined using a gradient descent algorithm. A prototype is fabricated to confirm manufacturability, and the improved efficiency of the proposed design is experimentally verified. The results demonstrate that the proposed IPMSM significantly outperforms the conventional SPMSM in terms of efficiency across both operating points. Full article

High-speed operation is a crucial approach for achieving high power density of drive motors for new energy vehicles. However, mechanical strength of the rotor has become the primary bottleneck in the development of high-speed drive motors. Adopting a multi-bridge structure can effectively enhance the mechanical strength of the V-shaped rotors widely used in interior permanent magnet synchronous motors (IPMSMs). Firstly, based on the equivalent centroid principle, the centrifugal forces generated by the rotor’s pole shoes and permanent magnets are calculated. An improved centrifugal force method is proposed to establish an analytical mechanical model of the multi-bridge V-shaped rotor structure. This method comprehensively considers the force conditions, deformation constraints, and material properties of the magnetic bridges. Additionally, stress concentration is taken into account to ensure the accuracy of the model. The effects of various structural parameters on the maximum mechanical stress and deformation are then analyzed. These parameters include the V-angle, pole shoe angle, and the dimensions of three types of magnetic bridges, namely, the central bridge, air-gap bridge, and middle bridge. Finally, recommendations for selecting structural parameters in the mechanical strength design of multi-bridge V-shaped rotors are summarized. The effectiveness of the proposed rotor structure is verified through finite element method and experiments. Full article

The handling of the remnants of rice crops in the field is not an easy operation, and farmers prefer burning, which causes air pollution, smog, and disease. This research reports the development of a novel precision crop seeder by handling the remnants of previous crops through mechanization. The precision seeder performed multiple operations in a single path, viz, chop residues, incorporate into soil, make mini trenches, and sow wheat with fertilizer application. The precision seeder has a 2040 mm working width, and specially designed C-type blades are used to shred the crop residue. A multiple-speed gearbox with a gear ratio of 1:0.52 is installed, with a further set of spur gears with 16, 18, and 20 teeth that provide 225, 250, 310, and 350 RPMs to the main rotor. In the middle of the seeder, after the main rotor shaft, 11 V-shaped trencher plates are fixed on the trencher roller for the making of trenches. The trencher roller is powered by star wheels, which showed good results. A zero-tillage-type sharp tip edge novel seeder unit was developed for the precise placement of seed and fertilizer. Seed and fertilizer were placed into the mini trenches through 11 seeder units through a ground wheel calibration system. The field capacity of the precision seeder was 0.408 ha/h and the operational cost was calculated 40.68 USD/ha. The seeder showed good results, with the production of 5028 kg/ha compared to conventional methods. The precision seeder provides a mechanized solution for wheat sowing with minimal operational costs by enhancing organic matter in soil with 13% more yield. Full article

This paper presents an improved solution for the airflow energy harvester based on the push–pull diamagnetic levitation structure. A four-notch rotor is adopted to eliminate the offset of the floating rotor and substantially increase the energy conversion rate. The new rotor is a centrally symmetrical-shaped magnet, which ensures that it is not subjected to cyclically varying unbalanced radial forces, thus avoiding the rotor’s offset. Considering the output voltage and power of several types of rotors, the four-notch rotor was found to be optimal. Furthermore, with the four-notch rotor, the overall average increase in axial magnetic spring stiffness is 9.666% and the average increase in maximum monostable levitation space is 1.67%, but the horizontal recovery force is reduced by 3.97%. The experimental results show that at an airflow rate of 3000 sccm, the peak voltage and rotation speed of the four-notch rotor are 2.709 V and 21,367 rpm, respectively, which are 40.80% and 5.99% higher compared to the three-notch rotor. The experimental results were consistent with the analytical simulation. Based on the improvement, the energy conversion factor of the airflow energy harvester increased to 0.127 mV/rpm, the output power increased to 138.47 mW and the energy conversion rate increased to 58.14%, while the trend of the levitation characteristics also matched the simulation results. In summary, the solution proposed in this paper significantly improves the performance of the airflow energy harvester. Full article

As one of the key components, low-speed direct-drive in-wheel machines with high compact volume and high torque density are important for the traction system of electric vehicles (EVs). This paper introduces four different types of outer-rotor permanent magnet motors for EVs, including one five-phase SPM machine, one three-phase IPM machine with V-shaped PMs, one seven-phase axial flux machine (AFM) of sandwich structure and finally one hybrid flux (radial and axial) machine with a third rotor with V-shaped PMs added to the AFM. Firstly, the design criteria and basic operation principle are compared and discussed. Then, the key properties are analyzed using the Finite Element Method (FEM). The electromagnetic properties of the four fractional slot tooth concentrated winding in-wheel motors with similar dimensions are quantitatively compared, including air-gap flux density, electromotive force, field weakening capability, torque density, losses, and fault tolerant capability. The results show that the multi-phase motors have high torque density and high fault tolerance and are suitable for direct drive applications in EVs. Full article

Magnetorheological fluids (MRFs) are composites of micron-sized and/or nano-sized Fe particles and nonmagnetic oils, and their rheological properties change with changes in the magnetic field. To distinguish between material and mechanical deterioration, we developed a durability test system without the influence of mechanical sealing and bearing on the MRFs. We used a set of rotors and stators to create a V-shaped MRF layer. However, the test device produces a constant magnetic field with a permanent magnet instead of an electromagnetic coil to make a compact design and cannot be tested under various dynamic magnetic inputs. Therefore, we developed a durability test system with an electric magnet to create a variable magnetic input and two sets of rotors, and compared their magnetic properties and the results of the durability tests. From the findings, the measured torque for the parallel plate case was lower than the predicted value. In contrast, the V-shaped disk exhibits a higher torque than the estimated values. Durability tests for the two types of MRFs were conducted. The torque variation for the nano MRF is significantly smaller for both the parallel and V-shaped plates. In addition, the duration of both MRFs for the V-shaped plate was much shorter than that for the parallel plate. Full article

In this study, the iron losses of high flux density concentrated winding-type interior permanent magnet synchronous motors for three different magnet shapes (single-V, single-flat, and dual-delta) and rotor structures are analyzed and compared. Iron loss is analyzed using the classical Steinmetz equation (CSE) based on the frequency separation approach using the iron loss material table, and each rotor type is compared. In addition, to validate the hysteresis loss for each rotor type, two additional analyses are performed. In the methods considered, the number of minor loops is counted, and the area is calculated based on DC bias. The eddy current loss is compared using two approaches: CSE base frequency separation and the homogenization method considering the skin effect. This study primarily focuses on the comparison of relative iron losses based on different rotor topologies instead of absolute comparisons. Full article

Due to the increasing energy crisis and environmental pollution, the development of drive motors for new energy vehicles (NEVs) has become the focus of popular attention. To improve the sine of the air-gap flux density and flux regulation capacity of drive motors, a new hybrid excitation synchronous motor (HESM) has been proposed. The HESM adopts a salient pole rotor with built-in dual-V permanent magnets (PMs), non-arc pole shoes and excitation windings. The fundamental topology, operating principle and analytical model for a magnetic field are presented. In the analytical model, the rotor magnetomotive force (MMF) is derived based on the minimum reluctance principle, and the permeance function considering a non-uniform air-gap is calculated using the magnetic equivalent circuit (MEC) method. Besides, the electromagnetic performance including the air-gap magnetic field and flux regulation capacity is analyzed by the finite element method (FEM). The simulation results of the air-gap magnetic field are consistent with the analytical results. The experiment and simulation results of the performance show that the flux waveform is sinusoidal-shaped and the air-gap flux can be adjusted effectively by changing the excitation current. This study provides design methods and theoretical analysis references for this type of HESM. Full article

Recently, a large amount of research on deep learning has been conducted. Related studies have also begun to apply deep learning techniques to the field of electric machines, but such studies have been limited to the field of fault diagnosis. In this study, the shape optimization of a permanent magnet synchronous motor (PMSM) for electric vehicles (EVs) was conducted using a multi-layer perceptron (MLP), which is a type of deep learning model. The target specifications were determined by referring to Renault’s Twizy, which is a small EV. The average torque and total harmonic distortion of the back electromotive force were used for the multi-objective functions, and the efficiency and torque ripple were chosen as constraints. To satisfy the multi-objective functions and constraints, the angle between the V-shaped permanent magnets and the rib thickness of the rotor were selected as design variables. To improve the accuracy of the design, the design of experiments was conducted using finite element analysis, and a parametric study was conducted through analysis of means. To verify the effectiveness of the MLP, metamodels was generated using both the MLP and a conventional Kriging model, and the optimal design was determined using the hybrid metaheuristic algorithm. To verify the structural stability of the optimized model, mechanical stress analysis was conducted. Moreover, because this is an optimal design problem with multi-objective functions, the changes in the optimal design results were examined as a function of the changes in the weighting. The optimal design results showed that the MLP technique achieved better predictive performance than the conventional Kriging model and is useful for the shape optimization of PMSMs. Full article