Internal Permanent Magnet Motor Research Articles

An improved equivalent magnetic network model of IPM motor in electric vehicles for dynamic simulation of transient effects

The existing electric motor model for electric vehicles cannot address the simulation of transient conditions. Moreover, it is difficult to balance the computation time and simulation accuracy. To address these shortcomings, an improved internal permanent magnet motor model containing nonlinear magnetic field factors was proposed based on the equivalent magnetic circuit theory. The effects of the magnetic circuit saturation, cogging torque, and magnetic field harmonics on the electromagnetic torque could be reflected. Furthermore, the electromagnetic vibration and rotor eccentricity could be considered. To improve the computational efficiency of the equivalent magnetic network method, lumped parameter or mesh-based methods were used for flux paths with different complexities. Second, the single-layer mesh-based method with local variable permeability parameters improved the efficiency of the air-gap dynamic analysis and computational efficiency while simulating 2D flux paths. The radial and tangential electromagnetic forces were calculated using the Maxwell tensor method and the action on the rotor. The accuracy of the nonlinear magnetic field modeling was verified by finite element analysis and experimental. In addition, the motion modeling method and dynamic characteristics of the model were studied. A reference was provided for dynamic simulations of electric vehicles and other using permanent magnet motors.

Reduction of Magnetization Current in a Variable-magnetization Internal Permanent Magnet Motor with Two U-shaped Arrangements for Electric Vehicles

Reduction of Magnetization Current in a Variable-magnetization Internal Permanent Magnet Motor with Two U-shaped Arrangements for Electric Vehicles

Retracted] Numerical Sensing and Simulation Analysis of Three‐Dimensional Flow Field and Temperature Field of Submersible Motor

In order to accurately study the temperature field distribution of the submersible motor, the author proposes the numerical sensing and simulation analysis of the three‐dimensional flow field and temperature field of the submersible motor. For a marine air gap water‐cooled internal submersible permanent magnet motor, based on the principle of computational fluid dynamics (CFD), numerical simulation analysis and geometric structure improvement of the three‐dimensional flow field and temperature field of the motor were carried out, eliminate the reverse flow phenomenon in the internal flow field of the motor, improve the heat dissipation efficiency of the whole machine, and optimize the flow field and temperature rise of the motor. Experimental results show that after the motor geometry is optimized, the flow rate of the cooling water in the air gap channel is 36.7 L/min, which is 7.9 L/min higher than the original model, it means that the heat in the motor can be better carried away by the water flow in the air gap channel. It is proved that the results obtained in this study have certain reference significance for the geometric structure design of the submersible motor.

Cogging torque reduction method of internal permanent magnet motor based on stator tooth shoulder chamfer

Cogging torque reduction method of internal permanent magnet motor based on stator tooth shoulder chamfer

Electro-Magnetic and Structural Analysis of Six-Pole Hybrid-Excited Permanent Magnet Motors

Potentials and limits of the Hybrid-Excitation Permanent-Magnet (HEPM) synchronous machine are dealt with in this paper. A six-pole machine is taken into consideration, and both parallel and series configurations are analysed and compared. Taking advantage of the rotor excitation coils, the permanent magnet (PM) rotor flux can be adjusted according to the operating speed to improve its performance parameters. The electro-magnetic force is analysed in its first harmonic and in the complete shape. Moreover, a comparison between analytical and numerical formulation has been done for the rotor current control. In particular, the speed range is extended, and electro-mechanical torque and power are increased, as well as the efficiency. It will be shown that the rotor flux reduction by using the excitation winding yields an improvement of the motor performance. The main advantage will be obtained during the flux-weakening operations. In this paper, different rotor topologies will be analysed to highlight the advantages and drawbacks of each of them, and how it is possible to achieve higher speed with higher torque and without high saliency ratio. A magnetic network will be introduced to explain the different contribution of the excitation winding to the rotor flux. Furthermore, a comparison of the amount of the volume of PM, copper and iron in internal permanent magnet (IPM) motor and HEPM motor will be analysed. Actually, an analysis of the harmonic content in the electro-motive force even varying the excitation current and a mechanical stress analysis of each machine will be shown. Finally, it will be verified that the excitation losses represent a minimum component of the total losses.

Reduction of Ripple Toothed Torque in the Internal Permanent Magnet Electric Motor by Creating Optimal Combination of Holes in the Rotor Surface Considering Harmonic Effects

Due to the widespread use of electric motors in various industries, it is very important to have optimally designed motors in that they have high efficiency and lower negative effects on the quality of the power grid. Therefore, in this paper, the effects of winding type (wide and concentrated) on ripple torque in internal permanent magnet motor (IPMM) are investigated. In order to reduce the ripple torque and to increase the average torque, by making optimal holes in the rotor surface and using the sensitivity analysis method, the structure of the IPMM is improved. In this method, the number, dimensions and location of holes are optimized using the sensitivity analysis approach, which reduces the ripple torque of the motor. Using a concentrated winding instead of a wide winding, the toothed ripple torque is reduced by approximately 75% while maintaining the average torque value. Also, by making holes in the rotor surface and optimizing them using the finite element technique and sensitivity analysis, it is demonstrated that the amount of ripple torque by 20%. In the proposed approach, it is proved that in the concentrated winding, in addition to reducing the spatial harmonics, the average amount of torque can also be improved. Obtained results of the simulation confirm the effectiveness of the proposed method.

Adaptive Maximum Torque per Ampere Control of Synchronous Reluctance Motors by Radial Basis Function Networks

As neodymium and other rare earth materials become a critical commodity, the exploitation of reluctance torque in synchronous motors is certainly an interesting option. Alternative motor topologies span from internal permanent magnet motors to pure reluctance machines. Anyway, any anisotropic structure suffers from some magnetic nonlinearities that call for more sophisticated models to get an efficient torque control. Neural network-based algorithms are good candidates for modeling the current-to-flux linkages curves of synchronous reluctance (SynR) motors, but so far their use was limited by the inherent complexity and the computational burden. This paper proposes the use of a special kind of neural networks, namely, the radial basis function networks, to get the magnetic model of any synchronous motor, including saturation and cross-coupling effects. Through experimental evidence, it will be shown that the structure is light enough to be implemented, trained, and self-updated online on standard high-end ac drives. The model is used to track online the maximum torque-per-ampere working point of a SynR motor drive.

Influence of the rotor angle precision in control of interior permanent magnet synchronous machine drives and improvement method using sensorless estimator with Hall sensors

This document studies torque degradation of an internal permanent magnet motor due to an incorrect rotor angle measurement when low rotor angle resolution sensors are used. The performance of the control with different rotor angle resolution is also analysed to determine the torque error due to the use of an incorrect synchronous rotating reference system. To address torque degradation due to the low resolution of Hall sensors, a new method of estimating the rotor angle is proposed that incorporates the information from Hall sensors. In this way, good resolution is achieved, allowing the machine to be controlled over a wide speed range even with rated torque. This method is validated through simulations and real experiments.

Magnetic Modeling of Synchronous Reluctance and Internal Permanent Magnet Motors Using Radial Basis Function Networks

The general trend toward more intelligent energy-aware ac drives is driving the development of new motor topologies and advanced model-based control techniques. Among the candidates, pure reluctance and anisotropic permanent magnet motors are gaining popularity, despite their complex structure. The availability of accurate mathematical models that describe these motors is essential to the design of any model-based advanced control. This paper focuses on the relations between currents and flux linkages, which are obtained through innovative radial basis function neural networks. These special drive-oriented neural networks take as inputs the motor voltages and currents, returning as output the motor flux linkages, inclusive of any nonlinearity and cross-coupling effect. The theoretical foundations of the radial basis function networks, the design hints, and a commented series of experimental results on a real laboratory prototype are included in this paper. The simple structure of the neural network fits for implementation on standard drives. The online training and tracking will be the next steps in field programmable gate array based control systems.

Identification of Three-Phase IPM Machine Parameters Using Torque Tests

This work presents a simple method for obtaining the main parameters, such as the torque constant and the d - and q -axis inductances $L_{d}$ and $L_{q}$ , for a brushless internal permanent magnet motor by measuring the machine torque during testing. These tests are relatively simple to carry out compared with other test procedures described in the literature, and they neither require sophisticated and expensive test equipment nor are they affected by temperature effects as happens with other techniques. The machine under test is supplied through a dc supply at different rotor positions. The shaft torque is measured through a torque sensor during the tests. The test current magnitude is varied to take care of the saturation effects. From the measured torque data and known rotor position, the required parameters can be obtained. Tests performed on two different internal permanent magnet machines confirm the validity and effectiveness of the proposed method.

On the Role of Robustness in Multi-Objective Robust Optimization: Application to an IPM Motor Design Problem

This paper discusses the different roles that robustness can assume when solving a multi-objective design optimization problem. A new role for robustness in multi-objective design optimization problems is proposed based on which an approach to conducting multi-objective robust optimization and finding the robust optima is suggested. This new approach is then tested on an internal permanent magnet motor design problem and the results are presented.

Visualization and Analysis of Tradeoffs in Many-Objective Optimization: A Case Study on the Interior Permanent Magnet Motor Design

The presentation and visualization of tradeoff solutions in many-objective optimization problems are difficult due to the large number of solutions in a hyperdimensional objective space. A recently proposed tool, known as aggregation tree (AT), can be used to analyze the degree of conflict between groups of objectives in a many-objective problem. In this paper, we present a case study on the internal permanent magnet motor design with seven objectives. The results show that the AT provides useful information about objective relationships (in accordance with the common knowledge of physics) as well as guidance in the reduction of objectives.

Integrated platform for motor stator sound power determination

This paper presents a unique approach for integrating the electromagnetic forces of a motor with the sound pressure level radiated from its stator frame. In addition, the effects of the inverter's pulse-width modulation (PWM) carrier frequency on the level of radiated noise are analysed. Four ANSYS modules, namely, Simplorer, Maxwell, Mechanical, and Acoustics, are used to develop the control circuit, to calculate the electromagnetic forces of the motor, to simulate the mechanical structure of the stator frame, and, finally, to predict the radiated noise. A Prius 2004 internal permanent magnet motor was selected for the study due to the availability of this motor's design details. An optimum PWM frequency was identified and a trap filter was designed for the noise reduction. A simple experiment setup was built to validate the correlation of the PWM switching frequency with the motor's radiated noise.

Characteristic Analysis of Moving Magnet Type Double-Sided Linear Synchronous Motor

Compared with double-sided permanent magnet linear synchronous motors (DPMLSM) with long secondary, the short secondary construction also has advantages of high dynamic performance and stable thrust, and is more suitable for the aspect of long-term acceleration. In this paper, magnetic field and characteristic of two different moving-magnet-type double-sided linear synchronous motors were analyzed by using 2D finite element method (FEM). The internal and external permanent magnet motor constructions with the same NdFeB and windings were compared according to flux density and electrical force. It was inferred that internal PM motors can provide the same force with lighter secondary weight and faster response speed.

A Practical Solution to Mitigate Vibrations in Industrial PM Motors Having Concentric Windings

Industry applications involving torque brushless dc motors require high efficiency over a large speed range. In order to achieve such specifications, flux weakening is necessary, which could lead to relative high electromagnetically induced vibrations and consequently to audible noises. Furthermore, in order to decrease cogging torque and to satisfy motor manufacturing constraints, concentric windings are usually considered. Such motor configurations lead to harmonics of the electromagnetic forces being the sources of mechanical vibrations. This paper focuses on the electromagnetic forces created in surface-mounted permanent magnet and internal permanent magnet motors for two concentric windings: one and two coil sides per slot. These forces are determined using both lumped magnetic scheme and two-dimensional finite-element (FE) simulations. Then, three-dimensional FE simulations enable to predict the mechanical modes and the acoustic radiated power. Finally, the authors propose a simple method to mitigate the magnetic forces and their variations. This method deals with skewing the stator. The skewing angle is optimized differently as in the usual case of decreasing the cogging torque. This method is really interesting for industry applications, because does not require any important change in the motor construction. The acoustic measurements confirm the analysis and the proposed improvement technique (stator skewing).

Internal Permanent Magnet Motor Design for Electric Vehicle Drive

Power compaction and high efficiency are two key advantages of permanent magnet motors. This paper proposes an enhanced internal permanent magnet motor that delivers high torque, power compaction, and exceptionally high efficiency in the same operation area. The advantage of the proposed scheme is the magnetic flux accumulation in the air gap, which allows much higher values of magnetic flux density, compared to a surface permanent magnet motor of the same size. The original contribution of this paper resides on the adopted motor configuration, enabling to efficiently utilize the energy stored in the permanent magnet and to provide total loss minimization at the most frequently used speed range.

Multi-Objective Optimization Applied to the Matching of a Specified Torque-Speed Curve for an Internal Permanent Magnet Motor

Traditionally, the objective function used for optimizing the design of an internal permanent magnet motor (IPM) has maximized efficiency or torque for a particular current or volume. Creating a particular torque speed curve can be considered to be a multi-objective problem and would usually be expressed in terms of a single objective by minimizing the average error over the curve. In this paper, it is proposed to treat this directly as a multi-objective problem thus allowing the designer to decide which tradeoffs in the torque-speed performance are most acceptable after the analysis has been performed rather than before. Additionally, a new variant of a multi-objective evolutionary algorithm using mixed elitism, intended for this problem, is described.