Rotor Permanent Magnet Synchronous Machine Research Articles

Multimaterial filtering applied to the topology optimization of a permanent magnet synchronous machine

PurposeThis study aims to propose a general methodology to handle multimaterial filtering for density-based topology optimization containing periodic or antiperiodic boundary conditions, which are expected to reduce the simulation time of electrical machines. The optimization of the material distribution in a permanent magnet synchronous machine rotor illustrates the relevance of this approach.Design/methodology/approachThe optimization algorithm relies on an augmented Lagrangian with a projected gradient descent. The 2D finite element method computes the physical and adjoint states to evaluate the objective function and its sensitivities. Concerning regularization, a mathematical development leads to a multimaterial convolution filtering methodology that is consistent with the boundary conditions and helps eliminate artifacts.FindingsThe method behaves as expected and shows the superiority of multimaterial topology optimization over bimaterial topology optimization for the chosen test case. Unlike the standard approach that uses a cropped convolution kernel, the proposed methodology does not artificially reflect the limits of the simulation domain in the optimized material distribution.Originality/valueAlthough filtering is a standard tool in topology optimization, no attention has previously been paid to the influence of periodic or antiperiodic boundary conditions when dealing with different natures of materials. The comparison between the bimaterial and multimaterial topology optimization of a permanent magnet machine rotor without symmetry constraints constitutes another originality of this work.

Magneto-Structural Combined Dimensional and Topology Optimization of Interior Permanent Magnet Synchronous Machine Rotors

A magneto-structural combined dimensional and topology optimization approach for interior permanent magnet synchronous machine (IPMSM) rotor design is proposed using the solid isotropic material with penalization (SIMP) density-based topology optimization method. This method optimizes the location and dimensions of the permanent magnets (PMs) embedded in the rotor, while simultaneously optimizing the lamination flux barriers using topology optimization. To allow for the location and dimensions of the PMs to change a Laplace smoothing mesh deformation technique is used. Three examples of IPMSM rotor optimizations are presented to demonstrate the proposed approach. In addition, a geometric template-based optimization is carried out for a comparison to one of the dimensional and topology optimized examples to better illustrate the difference.

2‐D analytical magnetic model for optimal design of an outer rotor permanent magnet synchronous machine

The objective of this paper is to investigate the optimal design of a 120 W outer-rotor permanent magnet synchronous machine for air-conditioning applications to reduce the electricity consumption and machine costs. To this end, a 2-D analytical magnetic model, combined with a teaching–learning based optimisation algorithm is employed. The objectives are to simultaneously maximise the machine efficiency and minimise the material cost. Constraints such as the required output torque, predefined machine volume, maximum allowable torque ripple and unbalanced magnetic force and limitations to avoid iron core magnetic saturation are imposed simultaneously. To find the flux density in iron parts, a new method based on the subdomain technique has been presented. To evaluate the analytical model in terms of accuracy and speed, the results of the 2-D analytical approach are compared with those of the 2-D and 3-D linear/non-linear finite element method. Finally, a prototype of the optimised machine is fabricated and the superiority of the presented approach is demonstrated.

An analytical model for stator yokeless radial flux dual rotor permanent magnet synchronous machine

PurposeThe purpose of this study is to propose an analytical model with consideration of the permeability of soft-magnetic materials, which can predict the magnetic field distribution more accurately and facilitate the initial design and parameter optimization of the machine.Design/methodology/approachThis paper proposes an analytical model of stator yokeless radial flux dual rotor permanent magnet synchronous machine (SYRFDR-PMSM) with the consideration of magnetic saturation of soft-magnetic material. The analytical model of SYRFDR-PMSM is divided into seven regions along the radial direction according to the different excitation source and magnetic medium, and the iron permeability in each region is considered based on the Maxwell–Fourier method and Cauchy’s product theorem. The magnetic vector potential of each region is obtained by the Laplace’s or Poisson’s equation, and the magnetic field solution is determined using the boundary conditions of adjacent regions.FindingsThe inner and outer air-gap flux density, flux linkage, output torque, etc., of SYRFDR-PMSM are predicted by analytical model, resulting in good agreement with that of finite element model. Additionally, the SYRFDR-PMSM prototype is manufactured and the correctness of analytical model is further verified by experiments on no-load back electromotive force and current–torque curve. Reasonable design of the slot opening width and pole arc coefficient can improve the average output torque and reduce output torque ripple.Research limitations/implicationsThe analytical model proposed in this paper assumes that the permeability of soft-magnetic material is a fixed value. However, the actual iron’s permeability varies nonlinearly; thus, the prediction results of the analytical model will have some deviations from the actual machine.Originality/valueThe main contribution of this paper is to propose an accurate magnetic field analytical model of SYRFDR-PMSM. It takes into account the permeability of soft-magnetic material and slot opening, which can quickly and accurately predict the electromagnetic performance of SYRFDR-PMSM. It can provide assistance for the initial design and optimization of SYRFDR-PMSM.

Fault Tolerance Method of Low-Resolution Hall Sensor in Permanent Magnet Synchronous Machine

The estimation of the motor rotor positions with high-precision based on low-resolution Hall sensors becomes an important trend to realize the vector control in low-cost permanent magnet synchronous machine (PMSM) based control systems. Most existing studies focus on the methods to improving the estimating precision of rotor positions, while the estimating precision of failed Hall sensors and the corresponding control strategies for fault tolerance is rarely explored. This paper proposes a method that can online estimate the position of a PMSM rotor with fault detection and fault tolerance. Such a method is able to achieve both stable and precise estimations on rotor position even when one or two Hall sensors fail. Meanwhile, it can meet the needs of vector control under variable speed and load on the PMSM. Finally, a dSPACE-based semi-physical simulation platform is established, which is used to validate the effectiveness of the proposed method with multiple experiments.

New finite element based method for thermal analysis of axial flux interior rotor permanent magnet synchronous machine

A new method for computing convection heat transfer coefficients in axial flux permanent magnet synchronous machines (AF-PMSMs) is introduced. The method is based on a two-step finite element analysis (FEA). In the first step, a simple 2D model is introduced and fluid flow and temperature fields are studied using computational fluid dynamic (CFD) technique. Convective heat transfer coefficients for all heat transfer surfaces of the model are extracted from CFD analysis and are then used as inputs to a 3D thermal finite element model. Two case studies are considered to check the accuracy of the abovementioned two-step method. One of the case studies is an air-cooled AF-PMSM that has air inlet and outlet on its enclosure and the other case is a totally enclosed AF-PMSM. The correctness of the mentioned method is verified by practical measurements on the second case. In addition, an experimental set-up is conducted to measure the temperature of different parts of the second case. It is observed that the results of the two-step CFD-FEA model are in good agreement with the experimental data. In the other case, the effect of inlet air velocity on heat transfer coefficients, as well as the thermal behaviour of the machine are explored.

Demagnetization fault detection by a novel and flexible modeling method for outer rotor permanent magnet synchronous machine

The research presents a novel technique for modeling of Outer Rotor Permanent Magnet Synchronous Machines (OR-PMSMs) in healthy and faulty cases with demagnetization fault based on an improved Magnetic Equivalent Circuit (MEC) method. Saturation effect is considered by a new method, where the B-H curve fitting is performed by using a novel nonlinear function. The machine properties such as the number of poles, number of slots, magnets size and all of the other parameters can be selected arbitrarily in the proposed model. Noticing to machine structure, the machine geometry is divided into 11 individual zones. Each of the flux tubes in the core is modeled by a nonlinear reluctance and the machine performances in both transient and steady-state conditions are studied. Various machine properties such as magnets arc, winding configuration, and slot skewing angle are analyzed and the dynamic behaviour is compared in various cases. Comparison with Finite-Element-Method (FEM) shows the effectiveness and accuracy of the proposed MEC method and much shorter processing time compared to FEM.

Low-Cost Dual-Mechanical-Port Dual-Excitation Machine for Washing Machine Application

This paper proposes a low-cost dual-mechanical-port dual-excitation machine for washing machine application. The proposed machine artfully combines two machines (vernier and permanent magnet synchronous machine (PMSM)). An outer vernier rotor is used for the low-speed washing operations, and an inner PMSM rotor is used for the high-speed drying operations of the washing machine. The proposed machine is compared with a similar recently presented machine to verify its cost-effectiveness. Comparison using the finite element analysis (FEA) shows that the ferrite magnets used in the proposed topology are more cost-effective. Furthermore, compared to the existing machine, the power factor of the proposed machine is high during the drying operation; hence, a lower rating inverter is sufficient to drive the machine, which further reduces the overall cost. In addition, the proposed machine provides similar efficiencies as the existing machine for both washing and drying operations.

Improved Nonlinear Flux Observer-Based Second-Order SOIFO for PMSM Sensorless Control

The conventional rotor flux estimation method has issues of dc offset and harmonics, which are caused by initial rotor flux, detection errors, etc. To eliminate these defects, one improved nonlinear flux observer is proposed for sensorless control of permanent magnet synchronous machine (PMSM). First, the rotor position estimation method based on PMSM rotor flux observation is studied. Meanwhile, the limitations of the traditional rotor flux estimators, i.e., the saturation of pure integrator, phase shift, and amplitude attenuation of a low-pass filter are analyzed. Then, two novel flux observers, second-order generalized integral flux observer (SOIFO) and second-order SOIFO, are designed for the rotor flux estimation of PMSM. Based on second-order generalized integrator (SOGI) structure, the SOIFO can limit the dc component to a certain value. Furthermore, the second-order SOIFO is developed from the SOGI, which is characterized with effective dc and harmonics attenuation capability. With the second-order SOIFO, even without magnitude and phase compensation, the dc offset and harmonics of estimated rotor flux could be well eliminated. Therefore, the speed and rotor position can be estimated accurately. All the performances of the four methods are analyzed by transfer functions and Bode diagrams. Finally, the new sensorless control strategy is validated by comprehensive experimental results.

Design, Analysis of the Location and Materials of Neodymium Magnets on the Torque and Power of In-Wheel External Rotor PMSM for Electric Vehicles

The technology of mounting electric direct drive motors into vehicle wheels has become one of the trends in the field of electric vehicle drive systems. The article presents suggestions for answering the question: How should magnets be mounted on the External Rotor Permanent Magnet Synchronous Machine (ERPMSM) with three phase concentrated windings, to ensure optimal operation of the electric machine in all climatic and weather conditions? The ERPMSM design methodology is discussed. Step by step, a method related to the implementation of subsequent stages of design works and tools (calculation methods) used in this type of work are presented. By means of FEM 2D software, various ERPMSM designs were analyzed in terms of power, torque, rotational speed, cogging torque and torque ripple. The results of numerical calculations related to variations in geometric sizes and application of different base materials for each of ERPMSM machine components are presented. The final parameters of the motor designed for mounting inside the wheel of the vehicle are presented (Power = 53 kW, Torque = 347 Nm; Base speed = 1550 RPM), which correspond to the adopted initial assumptions.

Semi-Analytical Magnetic Field Predicting in Many Structures of Permanent-Magnet Synchronous Machines Considering the Iron Permeability

This paper deals with an adaptable semi-analytical model to calculate the open-circuit and armature reaction field distributions as well as the electromagnetic performances in many structures of permanent-magnet synchronous machines (PMSMs). It is based on the multi-layer models considering the iron permeability with the convolution theorem (i.e., Cauchy’s product theorem) using the harmonic modeling technique (or the Maxwell–Fourier method). The 2-D semi-analytical model can be used for surface-mounted–inset-mounted or spoke-type PMSMs with different permanent-magnet (PM) magnetization patterns, winding structures, internal/external rotors, and slotless or slotted stators without the need to adopt the model equations to a specific PM machine type. For example, this scientific contribution has been applied to three types of PMSM with different topologies, viz.: i) slotted surface-mounted external rotor PMSM; ii) slotted surface–inset internal rotor PMSM; and iii) slotless external rotor spoke-type tangential PMSM. Finally, the results of semi-analytical method are compared with those found by the finite-element method.

A comparative design study and analysis of inner and outer rotor permanent magnet synchronous machine for power generation in vertical axis wind turbine using GSA and GSA-PSO

In wind energy conversion system, an electric generator is coupled with a wind turbine. The wind turbine is either vertical axis or horizontal axis wind turbine. To increase the efficiency the gear driven generator has been replaced by directly driven generator. This paper recounts the design optimization of inner and outer rotor permanent magnet synchronous machine of rating 500KVA, 3.3kV, 3-phase, and 600rpm. The weight of the generator has been taken as an objective function. The gravitational search algorithm and its hybridization with particle swarm optimization have been used as tools for optimization. The temperature rise, efficiency, regulation and maximum flux density in stator teeth are taken as constraints for design problem. The results of both types of generator configurations are obtained and compared. It is found that the efficiency of outer rotor permanent magnet synchronous generator is improved by 2.19% and regulation by 2.83% as compared to inner rotor permanent magnet synchronous generator. Lower temperature rise as 22.61°C is observed for outer rotor permanent magnet synchronous generator whereas it is 31.18°C in case of outer rotor permanent magnet synchronous machine. Further, the sensitivity analysis has been performed over design parameters using local sensitivity method for both generators.

Optimization of design with estimation of performance parameters of inner rotor permanent magnet synchronous machine used in VAWT using GSA and GSA-PSO

Permanent Magnet Synchronous Machine has been utilized in numerous applications, especially in WECS. This paper discusses the inner rotor configuration of PMSM i.e. IRPMSM and the design equations have been formulated in terms of design variables or physical parameters. The design formulation of a 500KVA, 3.3KV, 3 phases, 600rpm IRPMSM used in VAWT for WECS has been discussed where; the objective function for design of IRPMSM has been formulated by weight function, while temperature rise, efficiency, regulation and maximum flux density in stator teeth are used as constraints. The parameters estimation of electrical equivalent circuit of PMSM has been done while minimization the error function. With the estimated parameters, the performance of the machine has been estimated. The error function has been formulated using least square method and the error function obtained using output current of the machine. Both the problems have been optimized using GSA and its hybridization with PSO i.e. GSA-PSO. The formulated optimization problems is programmed in MATLAB and results using GSA and GSA-PSO have been obtained with required optimization curved of all the parameters. The sensitivity analyses have been performed using local sensitivity analysis over design parameters of IRPMSM.

Amplification of Single Mechanical Fault Signatures Using Full Adaptive PMSM Observer

This paper presents a localized mechanical fault detection method using a full adaptive permanent-magnet synchronous machine (PMSM) observer in a d / q reference frame. It appears that the fault sensitivity of PMSM stator currents and rotor speed measurements is very low with regard to single mechanical faults. That is why an amplification of single mechanical fault signatures in frequency domain is proposed by adjusting the adaptive PMSM observer gains. To study the influence of the adaptive PMSM observer gains on fault signatures, the observer model is first of all linearized at an operating point. Then, the static gain, the resonance, and the quality factor Q of different transfer functions are analyzed. A dedicated experimental setup based on an original mechanical fault emulator and a 7.8 kW PMSM drive is designed to validate the simulation results. The simulation and the experimental results show that the proposed method is effective to amplify single mechanical fault signatures and the calculated fault indicator.

Hall Effect Sensor Based Field Oriented Control of Permanent Magnet Synchronous Machine Using in Electric Vehicle

Field oriented control (FOC) of permanent magnet synchronous machine (PMSM) is of very importance in electrical vehicle (EV) applications due to low acoustic noise and smooth operation. Nowadays the resolver is most widely used to predict the PMSM rotor position. However, with cost consideration this paper proposes a FOC of PMSM based on Hall effect sensor, , which is very useful in practical applications because of low price and high reliability. Since the Hall effect sensor is an absolute position sensor with 60-degree resolution, the position initialization process is not needed and the reversal rotation risk can be avoided. To improve resolution the interpolation method implemented by software is employed. And the high performance of this proposed method is validated by some experimental results.

Parameter Estimation for Condition Monitoring of PMSM Stator Winding and Rotor Permanent Magnets

Winding resistance and rotor flux linkage are important to controller design and condition monitoring of a surface-mounted permanent-magnet synchronous machine (PMSM) system. In this paper, an online method for simultaneously estimating the winding resistance and rotor flux linkage of a PMSM is proposed, which is suitable for application under constant load torque. It is based on a proposed full-rank reference/variable model. Under constant load torque, a short pulse of id ≠ 0 is transiently injected into the d-axis current, and two sets of machine rotor speeds, currents, and voltages corresponding to id = 0 and id ≠ 0 are then measured for estimation. Since the torque is kept almost constant during the transient injection, owing to the moment of system inertia and negligible reluctance torque, the variation of rotor flux linkage due to injected id ≠ 0 can be taken into account by using the equation of constant torque without measuring the load torque and is then associated with the two sets of machine equations for simultaneously estimating the winding resistance and rotor flux linkage. Furthermore, the proposed method does not need the values of the dq-axis inductances, while the influence from the nonideal voltage measurement, which will cause an ill-conditioned problem in the estimation, has been taken into account and solved by error analysis. This method is finally verified on two prototype PMSMs and shows good performance.

Magnetic stray field based position detection in BLDC outer rotor permanent magnet synchronous machines

The stray field outside outer rotor permanent magnet synchronous motors can be used for rotor position detection. The focus of the research is on the optimal position of the sensors in order to provide accurate rotor position information. By using 2D and 3D models, the effect of the radial, circumferential and axial position of the sensors on the output signal is shown. Furthermore, the effects of the rotor yoke thickness and the stator current are studied: a thick rotor yoke obviously reduces the stray field amplitude, and high stator currents slightly shift the switching points of the Hall sensors, making the position information less accurate. Also, the rotor temperature and the orientation of the sensors towards the direction normal to the rotor surface are important: modifying the orientation causes a phase shift and is a way to tune the sensors without changing the position. Experiments show that an accurate brushless DC control is possible based on Hall sensors in the stray field. The motor and brushless DC control are used for a wheel drive of an ultra-light electric vehicle. Copyright © 2013 John Wiley & Sons, Ltd.

Voltage THD Improvement for an Outer Rotor Permanent Magnet Synchronous Machine

Abstract This article deals with the design of an outer rotor Permanent Magnet Synchronous Machines (PMSM) driven by wind turbines. The Voltage Total Harmonic Distortion (VTHD) is especially addressed, under design parameters’ handling, i.e., the geometry of the stator, the polar arc percentage, the air gap, the skew angle in rotor poles, the pole length and the core steel class. Seventy-six cases are simulated and the results provide information useful for designing this kind of machines. The study is conducted on a 5 kW PMSM.

Performance of Low-Cost Permanent Magnet Material in PM Synchronous Machines

Permanent magnet synchronous machines (PMSM) are considered a viable option in various types of applications. However, particularly in consumer and low-power industrial applications, the price may be a factor that limits the use of PMSMs. In addition to a different technology, the main reason for the high price of PMSMs is the use of expensive neodymium or samarium-cobalt magnets. Their use is necessary only if a high motor torque <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</i> to linear current density <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">A</i> ratio ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</i> / <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">A</i> ) is required. Ferrite permanent magnets are low cost, abundant, and have negligible eddy current losses in low-frequency applications such as motor drives. They have a much lower energy product ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BH</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> ) than the most modern magnets. Because of the high prices of rare earth magnets, many parties are seeking for opportunities to use ferrites instead. In the case of rotor surface ferrite magnets, the air gap flux density remains low. The air gap torque producing tangential Maxwell stress is proportional to the product of the air gap flux density <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">δ</sub> [ Vs/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ] and the linear current density <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">A</i> [A/m]. If the flux density is low and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">A</i> cannot be increased, the rotor has to be made larger than in machines having a high air gap flux density. In the case of multiple pole machines, the outer rotor approach, with its low rotor yoke height, offers an interesting alternative. The air gap diameter of these machines can be made larger than in conventional inner rotor type motors without increasing the machine outer dimensions. In this paper, an outer rotor PMSM with ferrite magnets is analyzed and tested. The machine characteristics in a fan drive are compared with an induction machine of the same power.

Design Analysis and Experimental Validation of a Double Rotor Synchronous PM Machine Used for HEV

The paper presents a new rotary actuator design—the double rotor permanent magnet synchronous machine (DRPMSM), which is to be used in hybrid electric vehicles (HEVs) as a four-quadrant drive system. The focus in this paper is placed on the electromagnetic design, construction and the experimental validation of the proposed DRPMSM. In contrast to other, this work evaluates the radial-radial electric machine concept with one permanent magnet per pole on the outer rotor. Because of the newly proposed outer rotor design, special attention has been given to investigation of the most appropriate stator-slot/outer-rotor pole/inner-rotor-slot number combination. The DRPMSM performance with six different slot-pole-slot combinations was evaluated based on postprocessing of results from time-stepping finite element analyses (FEA). It was elaborated that the combination 36-8-36 was the most appropriate. It is distinguished by low harmonic distortion in the back electromotive force, high average torque with low ripple, and low iron loss as well. A machine prototype based on the 36-8-36 design has been manufactured and rigorously tested in generator and motor operation.