Single-phase Permanent Magnet Research Articles

DC Offset Error Compensation of Current Sensor for Single-phase Permanent Magnet Synchronous Motor Drives

DC Offset Error Compensation of Current Sensor for Single-phase Permanent Magnet Synchronous Motor Drives

Enhancing Single-Phase Grid Integration Capability of PMSG-Based Wind Turbines to Support Grid Operation under Adverse Conditions

The proposed work delivers a robust control solution for a single-phase permanent magnet synchronous generator-based wind power conversion system (PMSG-WPCS) to enhance grid integration capability. The proposed control approach also offers an extended facility to fulfill low-voltage fault ride-through (LVRT) requirements under adverse grid conditions. Unlike the conventional observer-based PLL (O-PLL) approach, the proposed improved Lyapunov theory-based prefilter (ILP) is helpful in yielding a quadrature signal to solve the single-phase grid synchronization problem. Moreover, the proposed prefilter can leverage delayed signal operation, which improves the harmonic and the DC-offset component rejection abilities while eliminating the need for internal feedback-based submodule blocks for the case of an O-PLL. Consequently, the proposed ILP-PLL exhibits better dynamic behavior to rapidly synchronize a grid-tied power converter and can accurately track the fundamental amplitude information that is required for inverter control to meet the fault ride-through requirements. In addition, the suggested LVRT controller ensures smooth transition between the unity and non-unity power factor modes for superior converter control over reactive current injection into the grid to recover the grid from faults while maintaining a lower amount of total harmonic current distortions. The dynamic performance of the proposed control scheme is experimentally validated in view of the existing O-PLL approach for lower-rating wind-turbine-based PMSG-WPCS.

Design, Prototype and Experimental Verification of Single Phase Flux Switching Motor Using Low Cost Magnets

There has an increasing demand for a low cost brushless alternative to the series universal motor and single phase induction motor in domestic appliance and automotive applications. Single phase FSM with field winding has relatively low efficiency and low power factor. This paper tries to investigate a topology of single phase FSM which uses low cost magnet, i.e., Ferrite instead of field winding to provide field excitation. By using field focusing effect, the magnets are properly arranged to provide the required airgap flux. A standard design procedure for the presented FSM is developed. Extensive comparisons to the single phase induction motor, single phase permanent magnet motor and universal motor are made. A prototype with 8/4 pole configuration is fabricated. The experiment results are given and compared to the FEA simulated results. In addition, the electromagnetic vibrations and acoustic noises are also considered and measured which is always seen as the main disadvantage of this kind of motor.

Detent Force Reduction Design for the C-Core Single-Phase Permanent Magnet Linear Oscillation Actuator

Single-phase permanent magnet linear oscillation actuators (SP-PMLOAs) have been paid extensive attention in the field of compressors and industry applications. However, the detent force of SP-PMLOA limits the effective stroke and affects the control accuracy of the system. The purpose of this paper is to present a novel C-core SP-PMLOA with double stators arc-teeth and auxiliary slots to reduce detent force. Firstly, the basic structure and dynamic equation of the traditional linear oscillation actuator are introduced. Then, considering the magnetic flux leakage, the detent force formulation is derived by the flux tube method, and a novel structure is presented to reduce detent force and increase the effective stroke by the parametric scan. In addition, the traditional and presented structures of C-core SP-PMLOA are analyzed by 2-D finite element analysis (FEA) mothed. Finally, a prototype is built and tested to verify the results of FEA and calculations. The experimental results show that the presented structure can significantly reduce the detent force and increase the effective stroke.

Electromagnetic Design of Single-Phase Permanent Magnet Linear Oscillation Actuator Considering Detent Force Minimum

This article proposes an improved tubular single-phase permanent magnet linear oscillation actuator (SP-PMLOA) considering eliminating detent force for direct drive compressor applications. First, the flux tube method and Maxwell stress tensor are used to derive the end force and cogging force formulations based on the magnetic flux leakage of the magnet rings. Then, a novel model with minimum detent force is presented by finite element parametric sweeping. Finally, the electromagnetic performance of the three SP-PMLOAs is compared using 2-D finite element analysis (FEA), whose merits are evaluated, and the thermal distribution of the optimal PMLOA is analyzed using 3-D FEA. The predicted results show that the proposed structure not only can significantly reduce the detent force and the mover axial length but also can increase the thrust force-moving magnet mass ratio.

Performance analysis of single-phase interior permanent magnet synchronous motor

Single-phase permanent magnet synchronous motor has been tipped as an alternative to single-phase induction motor due to its high efficiency and torque density. Consequently, a proper performance analysis of the motor is required to cope with the stator imbalance in order to prevent pulsation in the torque performance. This paper presented the dynamic and steady-state analysis of a single-phase interior permanent magnet synchronous motor. In this analysis, a proper combination of direct-quadrature (d-q) reference frame, and symmetrical component analyses were used. The symmetrical components analysis was used to obtain the steady state performance while the dynamic performance was obtained from d-q analysis. The symmetrical components cope with the imbalance and hence the resulting torque pulsation which may results in heating of the motor. The results obtained agreed with the theoretical analysis and yielded a unique steady state equivalent circuit and phasor diagram. The models of the motor were simulated using MATLAB/Simulink. A prototype of the motor was developed and experimentation was carried out to validate the dynamic performance.

Noise and vibration characteristics of sub-fractional horsepower single-phase BLDC drives

Single-phase brushless DC (BLDC) drives are a cost-effective alternative for three-phase sub-fractional horsepower drives in automotive auxiliary applications. Inherent features of single-phase permanent magnet machines, such as high cogging torque and torque ripple, can, however, make them more audible than their three-phase counterparts. As some of these auxiliary drives are close to the passengers, where even a small amount of noise can be disturbing, the investigation into noise sources is essential to further address this challenge. In this paper, the dominant noise and vibration characteristics of single-phase BLDC machines are investigated for two different stator structures, i.e., salient-pole and claw-pole, and compared. Magnetic force density waves and finite element (FE) analyses are performed to analyze the electromagnetic forces resulting from the open-circuit condition as well as different switching strategies in the load condition. Structural analyses show that due to the mechanical structure’s lower stiffness and natural frequencies in the audible range, the example case machine with the claw-pole stator develops higher structure- and air-borne noise than the machine with the salient-pole stator.

Shaping the topology of a single phase BLDC motor for reduced cogging torque and improved performance

In the paper is presented a step-by-step development of the topology for a novel single phase permanent magnet (PM) brushless DC (BLDC) motor, aiming to improve its operation with more efficient utilisation of the active materials. The studied motor is based on a generic design, where asymmetrical stator poles and respective shaping of the permanent magnets is applied. Accurate 2D finite element simulations were employed for numerical prototyping of the motor design, until the expected results were obtained. Based on FEA, cogging and static torque waveforms, along with other relevant performance characteristics were determined and examined. The results show that the motor topology, and in particular, the detailed shape of the stator poles has the most important impact on the smooth operation of the single phase BLDC permanent magnet motor.

Synthesis and characterization of permanent magnetic oxide system Ba1-x-yLaxCeyFe12O19 system doped with La-Ce metal using wet mechanical milling method

The development of permanent magnet-based rare earth metals becomes a serious problem if the raw materials are difficult to find. The solution chosen is to utilize an oxide-based permanent magnet with little substitution of rare earth metals. In this study presented a permanent magnetic synthesis of barium hexaferrite-based oxides that were doped with La and Ce atoms. The synthesis of this material uses the wet mechanical milling technique to obtain the single phase permanent magnet system Ba1-x-yLaxCeyFe12O19 (x = 0, 0.02, 0.04 and y = 0. 0.05, 0.1). The precursor is weighed according to stoichiometric composition and is milled for 5 hours then compressed at a pressure of 7000 Psi. Sintering temperature for the formation of the barium hexaferrite phase at 1200oC for 2 hours. All samples after sintering were characterized using XRD and EDS. A single phase is obtained on all sample compositions with a hexagonal P63/mmc structure and is supported by elemental analysis data that each substituted sample contains elements La and Ce. Lattice parameters a, b, and c appear to decrease with increasing concentrations of La and Ce doping ions with a ratio of c/a in the range of 3.93-3.94.

Maximum Torque per Ampere Control of a Single-Phase Permanent Magnet Synchronous Motor, Part 1: Maximum Torque Capability Analysis

In this paper, a method for analyzing the torque capability of single-phase permanent magnet synchronous motor (SP-PMSM) is proposed. It is an important factor to verify the torque capability of a motor with respect to the motor design and control. This paper proposes the analysis of the motor capability under the inverter output voltage and current constraints using the phasor diagram. Since, the torque capability of the SP-PMSM is determined by both the DC-link voltage and rated current of the motor and the inverter, the torque capability curve of the SP-PMSM is analyzed through these limitations and the motor parameters. The magnitude and the phase of the inverter output voltage for the maximum torque per ampere are explicitly calculated. Several simulation and experimental results are presented to verify the proposed theoretical analysis.

Maximum Torque Per Ampere Control of a Single-Phase Permanent Magnet Synchronous Motor, Part 2: Variable Speed Control Method

In this paper, the control method for the minimum copper-loss operation of single-phase permanent magnet synchronous motor (SP-PMSM) according to given loads is proposed. The proper inverter output voltage to minimize a copper-loss is calculated from a voltage and current limit. Also, the inverter output voltage can be calculated for all load torque variations under the maximum torque capability curve of the SP-PMSM in all speed range. The proposed control method is simple and easy to implement since it has no inner current controller. The performance of the proposed method is verified by experimental results.

Cuckoo search as a tool for optimal design of PM brushless DC motor

PurposeThe purpose of this paper is to perform an optimal design of a single-phase permanent magnet brushless DC motor (SPBLDCM) by using efficiency of the motor as an objective function. In the design procedure of the motor, a cuckoo search (CS) algorithm is used as an optimization tool.Design/methodology/approachFor the purpose of this research work, a computer program for optimal design of electrical machines based on the CS optimization has been developed. Based on the design characteristics of SPBLDCM, some of the motor parameters are chosen to be constant and others variable. A comparative analysis of the initial motor model and the CS model based on the value of the objective function, as well as the values of the optimization parameters, is performed and presented.FindingsBased on the comparative data analysis of both motor models, it can be concluded that the main objective of the optimization is realized, and it is achieved by an improvement of the efficiency of the motor.Practical implicationsThe optimal design approach of SPBLDCM presented in this research work can be also implemented on other electrical machines and devices using the same or even other objective functions.Originality/valueAn optimization technique using CS as an optimization tool has been developed and applied in the design procedure of SPBLDCM. According to the results, it can be concluded that the CS algorithm is a suitable tool for design optimization of SPBLDCM and electromagnetic devices in general. The quality of the CS model has been proved through the data analysis of the initial and optimized solution. The quality of the CS solution has been also proved by comparative analysis of the two motor models using FEM as a performance analysis tool.

Design Comparison of Inner and Outer Rotor of Permanent Magnet Flux Switching Machine for Electric Bicycle Application

Recent advancements have led to the development of flux switching machines (FSMs) with flux sources within the stators. The advantage of being a single-piece machine with a robust rotor structure makes FSM an excellent choice for speed applications. There are three categories of FSM, namely, the permanent magnet (PM) FSM, the field excitation (FE) FSM, and the hybrid excitation (HE) FSM. The PMFSM and the FEFSM have their respective PM and field excitation coil (FEC) as their key flux sources. Meanwhile, as the name suggests, the HEFSM has a combination of PM and FECs as the flux sources. The PMFSM is a simple and cheap machine, and it has the ability to control variable flux, which would be suitable for an electric bicycle. Thus, this paper will present a design comparison between an inner rotor and an outer rotor for a single-phase permanent magnet flux switching machine with 8S-10P, designed specifically for an electric bicycle. The performance of this machine was validated using the 2D- FEA. As conclusion, the outer-rotor has much higher torque approximately at 54.2% of an innerrotor PMFSM. From the comprehensive analysis of both designs it can be conclude that output performance is lower than the SRM and IPMSM design machine. But, it shows that the possibility to increase the design performance by using “deterministic optimization method”.

Design and Performance of 8Slot-12Pole Permanent Magnet Flux Switching Machines for Electric Bicycle Application

This paper presents a new design and performance of single phase permanent magnet flux-switching machine (PMFSM) for electric bicycle application. 8Slot-12Pole design machine were choose by analyzing the highest power density value. All active parts such as permanent magnet and armature coil are located on the stator, while the rotor part consists of only single piece iron. PMFSM have a great advantage with robust rotor structure that make it much higher power and applicable for EV application compared to SRM and IPMSM. The design, operating principles, characteristics of torque, and power of this new topology are investigated by JMAG-Designer via a 2D-FEA. Size of motor and volume of PM is designed at 75mm and 80g, respectively. Based on the investigation, it can be concluded that the proposed topology of single phase 8Slot 12Pole PMFSM achieved the target of highest performance of power density, approximately at 0.113W/mm3 with reduced permanent magnet and size of design motor. Due to the low torque performance of this initial design, further works is ongoing to improve the torque performance. In future work, outer rotor PMFSM structure design will be presented and compared with the “Deterministic Optimization Method” to improve the initial design.

Design and analysis of linear oscillatory single-phase permanent magnet generator for free-piston stirling engine systems

This study focuses on the design and analysis of a linear oscillatory single-phase permanent magnet generator for free-piston stirling engine (FPSE) systems. In order to implement the design of linear oscillatory generator (LOG) for suitable FPSEs, we conducted electromagnetic analysis of LOGs with varying design parameters. Then, detent force analysis was conducted using assisted PM. Using the assisted PM gave us the advantage of using mechanical strength by detent force. To improve the efficiency, we conducted characteristic analysis of eddy-current loss with respect to the PM segment. Finally, the experimental result was analyzed to confirm the prediction of the FEA.

Status and prospect for multi-(hard magnetic) main-phase permanent magnet and coercivity mechanism

The mechanisms of magnetization and magnetic reversal have been reviewed. This review focuses on the design, the basic theory of controllable preparation and the mechanism of coercivity in novel composite rare earth permanent magnet of “multi-main-phase, multiscale” (including R-Fe-B/Nd-Fe-B, R-Fe-B/Sm-Co, and multi-main-phase). The novel two-main-phase (or multi-main-phase) composite rare earth permanent magnet has the advantages of different single phase permanent magnet and the preparation technology has been investigated. This paper discusses the mechanism of two-main-phase composite permanent magnet. Both the interaction between different hard permanent phases with different magneto-crystalline anisotropy constant, and the volume fractions and the distributions of different phases should be taken into account. Finally, the perspectives of permanent materials have been emphasized.

Optimal design of single phase permanent magnet brushless DC motor using particle swarm optimisation

Purpose – The purpose of this paper is to perform an optimal design of single phase permanent magnet brushless DC motor (SPBLDCM) using efficiency of the motor as objective function. In the design procedure performed on SPBLDCM, particle swarm optimisation (PSO) as an optimisation tool is used. Design/methodology/approach – The created computer programme for optimal design of electrical machines is based on the PSO. According to the design characteristics of SPBLDCM, some of the motor parameters are chosen to be constant and others variable. A comparative analysis of both motor models based on the value of the objective function, as well as the values of the optimisation parameters, is performed. Findings – From the comparative data analysis of both motor models, it can be concluded that the main objective of the optimisation is realised, and it is achieved by an improvement of the efficiency of the motor. Originality/value – An optimisation technique based on PSO has been developed and applied to the design of SPBLDCM. According to the results it can be concluded that the PSO is a very suitable tool for design optimisation of SPBLDCM and electromagnetic devices in general. The quality of the PSO model has been proved through the data analysis of the prototype and optimised solution. At the end, the quality of the PSO solution has been again proved by comparative analysis of the two motor models using FEM as a performance analysis tool.

Design and Experimental Analysis of AC Linear Generator With Halbach PM Arrays for Direct-Drive Wave Energy Conversion

To convert wave energy into more suitable forms efficiently, a single-phase permanent magnet (PM) ac linear generator directly coupled to wave energy conversion is presented in this paper. Magnetic field performance of Halbach PM arrays is compared with that of radially magnetized structure. Then, the change of parameters in the geometry of slot and Halbach PM arrays' effect on the electromagnetic properties of the generator are investigated, and the optimization design guides are established for key design parameters. Finally, the simulation results are compared with test results of the prototype in wave energy conversion experimental system. Due to test and theory analysis results of prototype concordant with the finite-element analysis results, the proposed model and analysis method are correct and meet the requirements of direct-drive wave energy conversion system.

Theoretical and experimental analyses of a single phase permanent magnet generator (PMG) with multiple cores having axial and radial directed fluxes

A new single phase generator has been designed and preliminary experimental results have been reported. The effects of two types of alternator cores have been explored. The proposed generator has one stator and two rotors with rare-earth-element-made permanent magnets (PMs). The physical and electromagnetic features of this PM generator are presented. The electromagnetic analyses are realized by the finite element method (FEM). The proposed machine has a combined type of flux directing mechanism, namely with axial and radial directions. The flux orientations are provided by 12 cores at the double-sided stator. The design has 2 rotors with totally 24 permanent magnets, which are positioned at different radial distances. It has been found that this design reduces the cogging torque values compared to the simple axial flux machine with 2 rotors having cylindrical cores. Thus a new cogging torque reduction technique is also proposed beside the new design. The electromagnetic simulations have been realized at different rotor speeds. The analyses also include the waveforms of currents, voltages, magnetic fluxes and cogging torque calculations. The maintenance and control of the machine is easier in operation, since the output power increases smoothly and become nearly constant up to the rotor speeds 1000rpm. Preliminary results indicate that peak-to-peak voltage Up=34V is generated at the rotor speed ω=200rpm and it increases linearly with ω. The rated speed is expected to be 1000rpm and 95% of efficiency is measured in the preliminary tests.

Performance Simulation and Analysis of a Novel Single-Phase Permanent Magnetic Synchronous Motor

This paper presents a novel energy-efficient single-phase permanent magnet synchronous motor with three-phase stator windings which are connected to two external capacitors in series connection, supplied by the single-phase AC power. The positive sequence impedance and negative sequence impedance of the novel single-phase permanent magnet synchronous motor are presented based on the symmetrical component method, the condition for balanced operation is analyzed and the method for determining the requested capacitances is also obtained. The simulation model of the motor is constructed in d-q stationary reference frame. The transient performance of the proposed motor is simulated and the simulation results proved the validity of the proposed motor.