PM Motor Research Articles

Self-Aligning Limited-Angle Rotary Torque PM Motor for Control Valve: Design and Experimental Verification

This study investigates the design and characterization of a permanent magnet torque motor with a limited operating range. The design method and configuration that satisfy the range and torque at a specific applied current were determined. The motor was designed and analyzed through finite element analysis. This motor was then fabricated, and an experimental setup was constructed to measure the torque at various rotation angles and different currents. Approximate values were obtained by comparing the finite element and measured results, and the characteristics of the limited-angle rotary torque motor obtained through the analysis were verified.

Design and experiment verification of OR‐PM machine with rectangular shaped magnets for integrated power generation

Outer-rotor permanent-magnet (OR-PM) machines provide several distinct advantages such as high torque density and large rotor inertia due to the large outer diameter of effective air gap for power conversion. The purpose of this study is to replace flywheel with the outer rotor by adopting OR-PM machines since this topology is well-suited for integration with diesel engines. This study specifically investigates a 16-pole–18-slot ring-shaped PM motor with rectangular shaped PM rotor for integrated power generation application. At first, the pole arc, rotor yoke thickness and PM slot height of the OR-PM machine with rectangular shaped PM are optimised. In addition, the no-load magnetic field, cogging torque and back-electromotive force of the OR-PM machine with rectangular shaped PM and have been analysed and compared based on two-dimensional finite element analysis. Additional comparison including torque characteristics, field weakening, cost and efficiency are also highlighted. The results show that the OR-PM machine with rectangular shaped PM has better electromagnetic performances. Finally, a 25 kW OR-PM machine prototype with rectangular shaped PM is manufactured and experimented. The predicted electromagnetic performance is validated by experimental results.

Efficiency Improvement of Outer-Rotor-type High-Speed PM Motor

Efficiency Improvement of Outer-Rotor-type High-Speed PM Motor

Single- and Two-Phase Open-Circuit Fault Tolerant Control for Dual Three-Phase PM Motor Without Phase Shifting

A fault tolerant control strategy for dual three-phase permanent magnet synchronous motor (DTP-PMSM) with 0° phase shifting between two windings is proposed in this paper. When a DTP-PMSM suffers from single- or two-phase open-circuit fault, to maintain the torque performance, current in faulty phase must be compensated by other healthy phases, which causes asymmetric self- and mutual inductances. Therefore, the 2nd harmonic component can be observed in the dq -axis currents and torque ripple also increases. To analyse this harmonic component in two types of faults, post-fault model of no-phase-shifting DTP-PMSM based on vector space decomposition (VSD) method is built in this paper. Then, proportion-integral-resonant (PIR) controller which can be used to suppress the specific periodic disturbance is applied to compensate the 2nd harmonic components. As the resonant controller is rarely dependent on motor parameters, phase and amplitude of current harmonic, the PIR controller can be applied in no-phase-shifting DTP-PMSM to suppress the harmonic caused by single- and two-phase open-circuit faults. The experimental results validate the effectiveness of the proposed fault tolerant control under single- and two-phase open-circuit faulty conditions.

A Novel Finite-Control-Set Model Predictive Current Control for Five-Phase PM Motor With Continued Modulation

The conventional five-phase finite-control-set model predictive control (FCS-MPC) suffers from heavy computational burden. Meanwhile, the control set with finite vectors inevitably leads to deteriorated operation performance. This article proposes a novel FCS model predictive current control (MPCC) with continued modulation. A cascaded optimization procedure is proposed, which includes main virtual voltage vector (VV) selection, determination of optimal combination of adjacent two VVs, and amplitude optimization. In this cascaded optimization procedure, the phase angle and the amplitude of the synthesized vector can be obtained in different steps. Also, there are two duty cycles calculated in different steps independently, which avoid overflow. By using this cascaded procedure, the continued modulation can be realized without using a modulator. Meanwhile, a vector selection method is introduced to reduce computational burden. This vector selection method avoids evaluation of all the candidate vectors without any negative effects. Moreover, the merits of conventional FCS-MPCC can be preserved. The experimental results verify the effectiveness and superiority of the proposed FCS-MPCC method.

Coupled physics solvers for analysing the magneto‐thermal behaviour of a permanent magnet synchronous machines

AbstractThe aim of this study is to present a thermal analysis of a permanent magnet synchronous machine based on the finite element method. The developed model can be used to predict temperature distribution inside the studied motor during the rated operation. Electromagnetic computation (EM) is carried out with the aid of two 2D finite‐element (FE) simulations on the cross‐section of the PM motor. To analyse the process of heat transfer (HT) in an electrical machine, empirical correlations are used to describe the convective (HT) from the different surfaces of the PM motor. The (HT) coefficient is determined using dimensionless numbers. The proposed numerical method to solve the coupled problem is based on independently and successively solving the (EM) and thermal problems and then transferring the results between the two sub‐problems. The results obtained by the model are compared with experimental results from testing the prototype electric motor.

Switching over technique to fault tolerant function of DC-bus battery in dual inverter motor drive

The dual inverter motor drive feeding an open-end winding PM motor is focused on for mileage improvement and autopilot technologies of hybrid and electric vehicles. Autopilot operation requires the fault tolerant functions which achieve to keep controlling the motor, even if some failure occurs in the system. In this paper, the fault tolerant function of the DC-bus battery in the dual inverter motor drive system is discussed. The system has a battery and a capacitor across the DC-bus of each inverter. The capacitor is utilized to keep operating the motor, instead of the failed battery in the fault tolerant function. In this time, however, it is necessarily to control the capacitor voltage of the failed side inverter at constantly with the space vector modulation (SVM). In particular, it is required to regulate the capacitor voltage of the failed inverter at a half of the battery voltage of the normal condition inverter. Therefore, the capacitor voltage must be discharged immediately after some failure is occurred in the battery of one of the inverters. In this paper, the switching over techniques from the normal condition to the fault tolerant function is proposed, and the proposed technique is examined through several computer simulations.

Reduction of Rotor Harmonic Eddy-Current Loss of High-Speed PM BLDC Motors by Using a Split-Phase Winding Method

Low-order harmonic currents in high-speed permanent magnet brushless dc (PM BLDC) motors cause large rotor eddy-current loss, resulting in high temperature rise and even overheating in the rotors, thus their application in the field of high-speed drive is limited. The rotor eddy-current loss can be reduced by using a split-phase winding method. In this paper, various time–space orders of harmonic eddy-current losses in the rotors of the PM motors with and without split-phase winding are quantified. The calculated results indicate that the rotor harmonic eddy-current losses generated by the low-order harmonic currents, which inherently exist in PM BLDC motors, are greatly reduced. Furthermore, associated with the characteristics of harmonic currents of PM BLDC motors, the mechanism of drastically reducing the rotor harmonic eddy-current loss of high-speed PM motors by using the split-phase winding method is revealed and experimentally validated.

Analysis of the PM Motor with External Rotor for Direct Drive of Electric Wheelchair

The paper deals with analysis of properties of synchronous motor with external permanent magnets rotor. The mathematical analysis and equivalent circuit of permanent magnet synchronous motor (SMPM) is presented. In the parts of the paper the electromagnetic design, construction design and FEM Simulation of a SMPM is described and its properties are analysed. In the paper the results of simulation in Matlab/Simulink of torque, speed and current on the base mathematical model are shown.

Design and Evaluation of a Short-Circuit Rotor-Ring for Enhanced Self-Sensing Capability in a Slotless PM Motor

This paper deals with the design and evaluation of a short-circuit rotor-ring for enhanced self-sensing capability in a two-pole slotless permanent-magnet motor. High-frequency rotor anisotropy is enabled by adding a short-circuited rotor-ring. Optimal ring-dimensions are determined by parametric numerical studies. An effective high-frequency saliency of up to 1.8 is demonstrated. The steady-state estimation error is within $\pm$ 2 $^\circ$ , practically unaffected by current level (in contrast to slotted self-sensing electrical machinery) due to the large effective air-gap. The proposed observer performs properly also during dynamic load changes. Fall-times from 3000 to 0 r/min in less than 50 ms with negligible overshoot are demonstrated. Also parasitic effects, such as power losses, heating, and torque ripple are analyzed.

Harmonic Model and Remedy Strategy of Multiphase PM Motor Under Open-Circuit Fault

Modular multiphase (MMP) PM motors have the ability to work continuously under a faulty mode. However, ripples in the spin torque of the motor and unbalanced forces incur rotor vibrations in postfault operations, which seriously degrade the performance of the PM motors. This paper presents a computationally efficient method to derive harmonic models for characterizing the pulsating torque and unbalanced forces of an MMP-PM motor under an open-circuit fault, and the corresponding optimal solutions to its inverse current model to remedy the fault. The model formulation, current harmonic identification, and remedial strategy for suppressing torque ripples and unbalanced forces are illustrated with an MMP-PM motor under an open-circuit fault; both odd and even number of phases are considered. The effectiveness of the harmonic models and remedy strategies are numerically validated with two typical (5- and 6-phase) MMP-PM motors under a one-phase/open- circuit fault and evaluated experimentally on a custom-designed 6-phase duplex motor .

Development of 10 kW turbo-Brayton refrigerator for HTS power applications

HTS power applications have been developed actively and the refrigerator requires larger cooling power. To satisfy this request we have developed 10 kW class turbo-Brayton refrigerator which has neon gas as working fluid. The refrigerator consists of a pair of turbine-compressors which have turbine, compressor and PM motor on the same shaft. The turbine-compressor has magnetic bearings with no rubbing parts, which results in a long maintenance interval. Neon gas is compressed from 0.5 MPa at inlet to 1.0 MPa at outlet by two compressors and expands through two turbines in parallel. Design cooling capacity is 10 kW at a cooling temperature of 65 K. We made a commercial model refrigerator and tested cool down characteristics, load cycles and cooling capacity using a liquid nitrogen circulation system. Specification and configuration of the refrigerator and test results are shown in this paper.

The Impact of Crude Oil Price Fluctuation on Tertiary Education Survival in Nigeria

Hybrid electric vehicles are becoming more popular due to environmental consciousness. Hybrid electric vehicles consist of a combustion and an electric motor. In practice, the effect of selecting appropriate electric motor is observable on all the main indices of vehicle performance such as maximum speed, gradeability, pollutant emission, fuel consumption, etc. In this paper, a review of different comparisons among electric motors for utilization in hybrid electric vehicles has been studied. Moreover, a more general and applicable comparison based on the performance of different electric motors in terms of standard design and utilization indices has been presented, in which induction motor and brushless PM motor are introduced as the two best candidates for hybrid electric vehicle applications. Finally, performance of these two candidates has been investigated in hybrid electric vehicle application benefiting ADVISOR software.

Multi-physics noise optimization in fuel pump PM motor

Multi-physics noise optimization in fuel pump PM motor

Modeling the Thermal Behavior of Permanent Magnet Synchronous Motors

The aim of this study is to present a thermal analysis of a permanent magnet synchronous machine based on finite element method. The developed model can be used to predict temperature distribution inside the studied motor during the rated operation. Electromagnetic computation is carried out with the aid of two 2D finite-element (FE) simulations on the cross-section of the PM motor. To analyse the process of heat transfer in an electrical machine, empirical correlations are used to describe the convective heat transfer from the different surfaces of the PM motor. The heat transfer coefficient is determined using dimensionless numbers and Nusselt number. After the loss calculation, the temperatures of the machine are calculated by using 3D finite element method. The results obtained by the model are compared with experimental results from testing the prototype electric motor.

Principle and Analysis of Doubly Salient PM Motor With Π-Shaped Stator Iron Core Segments

This paper investigates a novel three-phase doubly salient permanent magnet (DSPM) motor. Because of the adoption of Π-shaped stator iron core segments, the asymmetrical magnetic circuit among different phases occurring in conventional DSPM motors with E-shaped stator iron core segments can be avoided, so that balanced and sinusoidal three-phase PM flux linkage and no-load electromotive force (EMF) can be achieved. First, based on a 12/7 stator/rotor pole combination, the operation principle of Π-core DSPM motor is discussed using the least magnetic reluctance principle. Then, the general airgap field modulation theory is extended to the Π-core DSPM motor for explaining its operation principle further and armature winding connection. The finite element analysis is used to validate theoretical analysis, as well as to calculate its electromagnetic performances. The results show that the 12/7-pole Π-core DSPM motor possesses higher average torque output capability and lower torque ripple compared with the 12/8-pole E-core counterpart. Finally, a 12/7-pole Π-core DSPM motor is built and tested so as to experimentally verify the theoretical analysis.

Multiobjective Optimization of a Double-Side Linear Vernier PM Motor Using Response Surface Method and Differential Evolution

This paper designs a double-side linear vernier permanent-magnet motor, which incorporates the merits of high thrust force capability, high power factor, and high efficiency. Since the parameters of the motor are very sensitive and the high thrust force capability comes along with the high force ripple, a framework of multiobjective optimization is proposed to improve the overall motor performances. The sensitivity analysis is used to select significant variables and the multiobjective differential evolution with ranking-based mutation operator is conducted with the response surface models to generate the Pareto solution set. The electromagnetic performances of the optimal motor are compared with the initial motor by simulating step by step based on finite-element analysis. Finally, a prototype motor is manufactured and the experimental results validate the improved motor performances.

Design and analysis of PM motor with semi-circle stator design using 2D-finite element analysis

<p>This paper presents a basic approach to reduce an overall weight of selected PM motor. The approach is not based on normal sizing step by keeping the overall design in symmetry dimension, but by introducing semi-circle stator design. The investigation takes 12-slot/10-pole motor as a subject due to it symmetric winding disposition. Two designs are included, both having identical semi-circle stator but different in rotor configuration. Design 1 has a standard rotor design that equipped with 10-pole while Design 2 has a semi-circle rotor design following the stator design. This inherently result an even number of pole i.e. 5. From the investigation using 2D-Finite Element Analysis, an overall weight in PM motor can be theoretically reduced by having asymmetric design dimension. However, motor torque performance would deteriorate and unwanted noise may exist due to high cogging torque and high output torque ripple. A proper design procedure that includes parameter optimization and intelligent switching for optimum current excitation is required to restore the desired torque.</p>

Study of Proposals and Torque Vibration Reduction Structure of the 16-pole 18-slot IPM Motor for Mild Hybrid

The efficient construction method of mild hybrid is to minimize the mechanical loss by directly connecting the engine and the assist motor. The shape of the motor to be directly connected to the engine output shaft has a flat structure with a diameter of 250 to 300 mm and an axial length of 60 to 90 mm, and various multipolar PM motors have been proposed in order to obtain high output and high power generation. As a slot pole combination, it is known that a combination of 8-9 is good, but it was said to be impractical due to the problem of magnetic imbalance due to eccentricity. For large diameter motors, it is possible to configured with 16-18, twice the basic configuration. In this paper, we propose an IPM motor with 16 - 18 - combination for mild hybrid considering performance and low vibration during startup and power generation. The usefulness of 16 poles and 18 slots combination and the cogging torque · torque ripple reduction structure were clarified by finite element analysis.

Effects of Teeth Length and Magnet Material on Characteristics and Effects on Conductor Eddy Current Loss due to Changes in the number of Strands of Litz Wire of Low Voltage Drive High-Speed Motorp

High-speed motor driven in low voltage are used in equipment such as electric reel and handy vacuum cleaner. If a motor with a general structure used in an operating range of several thousand revolutions is used as it is in a high-speed range of several tens of thousands of revolutions, efficiency will decrease due to a large amount of iron loss. In this paper, we proposed models in which the stator teeth length and the magnet material were changed in order to suppress the iron loss that causes the efficiency reduction of the high-speed PM motor. In this case, since the eddy current loss occurs in the armature conductor, the effect of reducing the conductor eddy current loss by using the Litz wire was also examined. As a result, it was shown that the proposed model improves the efficiency compared to the conventional structure.