Determining force characteristics of an electromagnetic brake using co-energy

Conventionally, for a tubular permanent magnet synchronous linear motor (TPMSLM), adopting a modular structure can effectively reduce the detent force; however, the thrust density is sacrificed via the large proportion of the flux barrier to the total primary component volume. To overcome this disadvantage, this paper proposes a novel modular TPMSLM, in which the unit primary component adopts the large slot structure containing several coils. Focusing on this motor, research on the flux linkage characteristic is performed to obtain the design principle, and then the detent force is analyzed and suppressed by reasonable design of end teeth. First, the flux linkage characteristics of the unit motor and the whole motor are investigated. Variation rule of the coil flux linkage affected by the end tooth is discussed, and the principle of realizing three-phase balance for the whole motor flux linkage is elaborated. Moreover, the principle of the detent force suppression is verified and the detent force is further suppressed through the end tooth design. Finally, a prototype is developed. The back electromotive force and the detent force were tested, which verified the effectiveness of the novel modular TPMSLM proposed.

Problem statement: The Switched Reluctance Motor (SRM) is an old member of the Electric Machines Family. It’s simple structure, ruggedness and inexpensive manufacturing capability make it more attractive for Industrial applications. Now, the applications of switched reluctance motors in various industrial fields are tried by many engineers. However, switched reluctance motors are not used so far in submersible underwater motor for agriculture purposee. The torque developed by an SRM is dependent on the change of flux-linkage and rotor position. The flux linkage characteristic of the motor is required to make the control circuit. Since the SRM is non-linear in nature, estimation and calculation of the flux linkage characteristics is very difficult. Approach: With the flux tube method concept a simple algorithm is being developed in a MATLAB. ANSYS Software is used to determine the flux distribution at various rotor positions. Results: The aligned and unaligned flux linkage values for theoretical calculation at a current of 7 A is 72.7 mwb and 13.79 mwb respectively. With FEA simulation the obtained value is 92.73 mwb and 19.175. Conclusion: In this and, a simplified method for the determination of flux linkage characteristics of submersible SRM using MATLAB has been presented. The obtained value has been validated with the ANSYS FEM method. the calculated unaligned and aligned inductance values of a 4- phase, 3 hp, 220 V Submersible SRM using simplified MATLAB method very much matches with the ANSYS FEM Method.

This article presents a simple and practical method to estimate the lumped radial force characteristics for the switched reluctance machines (SRMs). First, the relationship between the square root of the lumped radial force and the flux linkage is discussed and analyzed. With the geometry data of the studied SRM, the abovementioned relationship under nominal air-gap length and nominal material magnetic property conditions can be obtained through the finite-element analysis (FEA) software. As the radial flux density dominates the magnitude of the radial force and it concentrates on the overlapping area, the abovementioned relationship is analyzed to be roughly held when the air-gap length and/or material magnetic property vary. Based on this relationship obtained from the FEA and the actual measured flux-linkage characteristics, the lumped radial force can be easily reconstructed for the actual SRMs regardless of the possible air-gap length variation and material magnetic property deviation during the manufacturing process. Simulation results on the 8/6 SRM and 12/8 SRM verify that the proposed method provides good radial force estimation results when the air-gap length is reduced or increased up to 50%. Superior estimation results are also observed on the condition that the magnetic <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${B}$ </tex-math></inline-formula> – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${H}$ </tex-math></inline-formula> curve is linearly varied by ±25%. The accurate and simple radial force estimation method proposed in this article provides a solid basis for the radial-force-shaping-based advanced control methods to suppress the acoustic noise.

Accurate calculation of the flux linkage characteristics is the basis of design and control of bearingless switched reluctance motor (BSRM). In this paper, flux linkage of main-and suspended windings for a BSRM were calculated by using 3D finite element method (FEM). A new subregional fitting algorithm was proposed and a novel mathematical model of flux linkage was built by using fourier series and Levenberg-Marquardt(LM) optimization method. Based on the new model, the incremental inductance, back-emf factor and instantaneous torque were obtained. This will provide important theoretical basis for the analysis, design and control of the BSRM.

Switched reluctance motors have complex problems such as strong nonlinear characteristics, variable given speed, and large load disturbances. Aiming at the problem that the switched reluctance motor cannot adapt to the changing speed and large disturbance under the traditional PI control, this paper combines the fuzzy control and the PI control to form the fuzzy-PI controller, which constitutes the fuzzy adaptive speed regulation system of the SRM. Using fuzzy control to correct system parameters in real time can improve the situation that the traditional PI direct torque control system cannot effectively control the strong nonlinearity of SRM. By accurately establishing the nonlinear model of the SRM, and using the finite element simulation software to calculate the static characteristics of the motor's flux linkage, inductance and torque, the mathematical model of the SRM speed control system is established. Then it is shown by MATLAB/Simulink simulation, compared with the traditional PI control algorithm, the fuzzy-PI control algorithm can make the SRM system achieve better control effect in the case of variable speed and large load disturbance, improve the dynamic response of the system, reduce the overshoot, and enhance the robustness.

This paper presents a procedure of determination of static characteristics of switched reluctance machines (SRMs). Calculations are realized for two SRM topologies including novel configuration with 8 stator and 14 rotor poles (SRM 8/14). This configuration is based on new pole design formula introduced recently. Flux linkage and static torque characteristics are calculated for different rotor positions and stator currents using two-dimensional finite element analysis (2D-FEA). Simulation results for new SRM 8/14 and conventional SRM 8/6 with the same number of phases and outer dimensions are presented and compared. This comparison shows that new configuration can have better torque density. Therefore, new design approach should be considered to make this type of machines a more attractive for high performance HEV's (Hybrid Electric Vehicle's) drives.

A new structure for a hybrid motion switched-reluctance motor (SRM) is presented in this paper. The hybrid motion originated from the ability of the motor to operate in three modes: 1) rotary; 2) linear; and 3) rotary–linear, which can be named a new rotary–linear SRM. The design is in such a way that both rotary and linear motions can be controlled independently. The motor is composed of a three-phase 6/4 rotary SRM with Clockwise-Counterclockwise motions and a two-phase transverse flux linear SRM with forward–backward movements. The hybrid motion control does not need any decoupling control algorithm, which is an important issue in the other rotary–linear motors. In addition, a sensorless method for the motor control is provided. The motor design is performed based on the analytical approach. According to the obtained parameters, the motor 3-D model is utilized for electromagnetic assessment. The dynamic 3-D finite-element analysis is used to evaluate motor’s flux linkage, torque, speed, current, torque ripple, torque/speed, and force characteristics. The optimum operation is considered with choosing the proper dwell angle. To verify the design, a prototype is constructed in the laboratory and compared with other structures to show the performance and applicability of the proposed motor.

Due to the special rotor configuration, the coil flux linkage of permanent magnet (PM) excited segmental rotor flux switching machine (SRFSM) can be considered as the sum of the flux linkages produced by each of the adjacent PMs. Then, the hybrid excited SRFSM is obtained by replacing one PM in every pole pair by field winding to obtain high magnetic field regulation capacity. The configuration and operational principles are first discussed. To reduce the computation time, the analytical model of hybrid excited SRFSM with the subdomain method is developed. The electromagnetic performances such as the flux linkage, back electromotive force, electromagnetic torque, and eddy current loss in PM and rotor support are investigated using the analytical model. Furthermore, the effect of machine parameters on the torque ripple and average torque, and the effect of field current density on the flux weakening capability are also analyzed. The analytical results are verified by the finite-element method and prototype machine experiments.

This article presents the process of building a hybrid analytical model (HAM) for surface-mounted permanent-magnet machines. The HAM couples a reluctance network (RN) model in the stator region with a magnetic scalar potential analytical model in the air gap and magnets regions. This hybrid model can deal with the slotting effect with straight teeth, and takes magnetic saturation into account in the stator iron material using the RN model. It is calculated under open-circuit and loaded conditions. The magnetic flux density, flux linkage, back electromotive force (EMF), and torque of the machines are also calculated. This hybrid model is compared with the subdomain method. It is also compared with the finite element method (FEM) both in terms of the size of the matrix that needs to be calculated and in terms of the torque error. We analyzed this method for two surface-mounted permanent-magnet machines, one with a symmetry factor of four and another with a symmetry factor of three. In both cases, HAM reduced the size of the matrix that needed to be solved compared to FEM. In the machine with a symmetry factor of three, when the matrix size of both FEM and HAM was around 1700 × 1700, the torque error of FEM was 2.62% compared to the high-mesh-density FEM simulation, while the torque error of HAM was only 0.17% compared to the same simulation. HAM also had significant advantages over the subdomain method, as it reduced the torque error from 16.8% to 0.08% in the case of high magnetic saturation. The HAM can, hence, play a significant role in the design and optimization of surface-mounted permanent-magnet machines, especially in cases where magnetic saturation is present.

Determination of flux linkage characteristics is a central step in electromagnetic modeling. The flux linkage, a group of curves varying with phase current levels and rotor positions, is required very accurate, on which main outputs such as torque, radial force and iron loss highly depend [1, 2]. However, modeling of flux linkage, a seemingly simple question, is still under study, especially for electrical machines with salient poles. This is because of the saliency that leads to rotor position dependent airgap paths together with magnetic saturation. Further in this study, flux linkage curves are complicated by adding can-shields in airgap. Due to electrical resistance of cans, the alternating airgap flux will induce eddy current circulation, which will in turn affect that airgap flux, making a coupled relation.

The presented work discusses the vibration behavior of an axial turbine, analyzed using the finite element method (FEM) using commercial software ANSYS®. The turbine was modeled as a 2-D plate type of structure discretized with 4-noded shell 63 elements to save computational time. Constraints were applied keeping in view the actual operating conditions. The turbine was modeled with more than one FE meshes. Mesh sensitivity analysis was carried out to ensure the quality and independence of the results. Modal analysis was conducted to calculate a few initial natural frequencies. Results were studied against the operating frequency of the turbine. After carrying out the modal analysis, harmonic analysis was performed to see the response of the turbine under dynamic loading. The nature and cause of the dynamic loading are also discussed in relation to dynamic behavior. It was observed that the turbine is safe in its entire range of operation as far as the phenomenon of resonance is concerned. Also, it was observed that the maximum harmonic response of the turbine on the application of dynamic loading is far lesser than its failure limit within the specified operating range.

Double stator (DS) linear-rotary actuators (LiRAs) are mainly used in machining applications with high force and torque demands, such as milling or turning. The mover of a typical DS LiRA contains two sets of permanent magnets, one arranged as in radial-flux rotating machines and the other as in tubular linear machines. A back iron is sandwiched between these two sets of permanent magnets, rendering the mover heavy and bulky. Consequently, DS LiRAs are not suitable for applications with high dynamics, such as pick-and-place robots in the packaging and semiconductor industries. In order to increase the dynamics of DS LiRAs, two different ironless mover layouts are proposed in this work. The achievable forces and torques are calculated using finite element method (FEM) simulations and compared to the standard DS LiRA. Manufacturing limitations of the proposed mover layouts and their influence on the performance are considered. Moreover, cogging force and cogging torque of the standard and proposed LiRAs are compared. To verify the FEM models used in the analysis, a simplified test setup with a flat mover is presented. The flux linkage is measured and a good agreement with FEM simulations is demonstrated.

The three phase flux reversal machine (FRM) is a doubly salient permanent magnet machine with concentrated windings. This study proposes the distributed winding for this machine. This winding (i.e. full pitch winding) offers high-power density and improves the efficiency. The permanent magnet (PM) flux linking the stator winding has effectively two or four pole flux pattern, which depends on the number of stator poles and independent of number of rotor poles. Finite element method (FEM) analysis is performed on the concentrated stator pole winding FRM (CSPFRM) and proposed full pitch winding FRM (FPFRM) to obtain induced EMF, flux linkages and inductance of the winding. The inductance of both machines is also obtained using winding function approach and compared with FEM results. The effect of armature reaction is compensated by capacitive series compensation to improve the voltage regulation. FEM analysis is also carried out on both the compensated generators to evaluate the power density. Speed of the flux pattern and that of the rotor is different in FRM. The ratio of these two speeds is termed as fictitious 'electrical gear'. FRM and permanent magnet synchronous machine (PMSM) have sinusoidal terminal voltage and surface mounted PMs. The power density of both machines is compared using the concept of fictitious 'electrical gear'. To verify the above analysis, a 6/14 pole FRM with distributed and concentrated winding is designed and fabricated. The experimental results are in close agreement with simulated results.

A Hybrid Axial Field Flux-Switching Permanent Magnet machine (HAFFSPMM) which is suitable for electrical vehicle drive is proposed in this paper. The size equations of the HAFFSPMM, including the power-size equations and the winding part, are deduced. According to the equations, a 3-phase 6/10 stator/rotor-pole HAFFSPMM is designed and the electromagnetic performances, such as the PM flux linkage, no-load back-EMF, cogging torque, torque-current characteristic and the field regulation capacity, are investigated based on 3-D finite element method (FEM). A prototype is manufactured and the experiments are done, which validates the design method and the predicted FEM analysis.

Scale-Effect on energy performance of a Reduced-Scale Trombe–Michel solar system