Search

A Dual three-phase winding configuration in a 12-slot 10-pole Brushless Alternative Current Synchronous Motor (BLAC) has been adopting in electrical power steering systems. The main aim of this winding configuration is to get a fault tolerance capability when the motor is a failure. Different arrangements of the coils of the windings are possible to separate the three-phase winding. In this paper, we investigate the effect of the various winding configurations for the fault tolerance on the iron losses of the BLAC motor. To calculate accurate iron losses, we use the instantaneous distribution of magnetic flux from a two-dimensional finite-element method. As a result, we suggest the most effective winding configuration to make the BLAC motor efficiency in the event of the fault.

This paper presents a unique method for simulating permanent magnet motors without time-consuming numerical methods used in the conventional magnetic circuit method. The conventional method gives us average values like torque and power over specified periods of time, but it is usually very difficult and time-consuming to obtain instantaneous characteristics like cogging torques and torque ripples. The convolution operations method we present, however, considers relative angle variations of stator magnetic circuits and rotor magnetic circuits. As a result, it makes uses of instantaneous values possible. The authors compare the new method with the coventional method and verify that calculating cogging torque values and back-emf values is possible with the proposed new convolution method.

This paper introduces two types of magnetization, and reports the effect of the magnetization direction on the iron loss in a brushless DC (BLDC) motor using a 2-D time-stepped voltage source finite-element method (FEM). The iron losses were found to consist of hysteresis and eddy current loss, which were calculated from the time variation of the magnetic field distribution. To confirm the analysis, a prototype BLDC motor was constructed with a sintered ferrite magnet. The analysis and experimental results suggest that the magnetization direction has a significant effect in terms of the iron loss characteristics of the BLDC motor.

The flat-type vibration motor has an axial-gap structure. Analyzing axial-gap motors with the two-dimensional (2-D) finite-element method is very difficult because we have to define the analysis surface as a cylindrical surface. In order to simulate the flat-type vibration motor, we have developed new equations of calculation for the torque of the motor, which is uses a 2-D grid model. We have measured the load torque of the vibration motor which is used for the motion transient analysis. The simulated vibration characteristic is compared with experimental value

This paper describes the effect of pulsating current generated by back-electromotive force (BEMF) current of switch-off phase in flux-reversal machine (FRM) which is driven by 120deg square wave voltage sources. A two-dimension time-stepped voltage source finite element analysis using a direct convergence method is proposed to analyze an electromagnetic field and the BEMF current. To prove the propriety of the proposed analysis method, we build the prototype FRM and a digital signal processor (DSP) installed controller as a set for the experiment

This paper presents a characteristic analysis of switched reluctance motor (SRM) considering hard chopping and dc link voltage ripple by using time-stepped voltage source finite element method in which the magnetic field is combined with drive circuit. We also examine the influence of freewheeling diodes and dc link voltage ripple on the performance of a SRM such as torque ripples and radial force on the surface of the teeth. The freewheeling diodes and dc link voltage ripples must be taken into account in predicting the performance of the SRM.

The cogging torque of the flux-reversal machine (FRM) may cause some problems like noise and vibration of the motor. By FEM analysis of the cogging torque of FRM, a noticeable feature was found that the rotor teeth width increases, phase and magnitude of the cogging torque varies. So, the rotor teeth pairing method is proposed for reducing the cogging torque of FRM. In this method, we made a rotor which has two different tooth widths and measured the cogging torque of the motor. From the result, we can see that the simulation result is well matched with the measured result and the proposed method is feasible.

A novel permanent-magnet flux-concentration-type linear oscillatory actuator (LOA) for a compressor is analyzed in this paper. The losses of a flux-concentration-type LOA which is driven by sinusoidal and rectangular-shaped current are compared using finite-element method (FEM). In this computation, the equation of magnetic field is coupled with the equation of the driving electric circuit and the equation of motion. The results are compared with respect to iron losses. The eddy-current loss and hysteresis loss of both the sinusoidal current and rectangular current was calculated using two-dimensional FEM.

The three-phase flux reversal machine (FRM) is a doubly-salient stator-permanent magnet machine with flux linkage reversal in the stator three-phase concentrated windings. It can operate in both motoring and generating modes. In this paper, we identify stator/rotor geometrical design variables that influence the cogging, interaction torques, and winding flux linkage using a two-dimensional finite-element method and the flux-magnetomotive force diagram technique. Also, the novel design to improve the performance of the FRM is studied both theoretically and experimentally.

This paper presents an approximate optimization that is able to determine optimal geometric and electrical design variables of switched reluctance motor. In order to reduce torque ripple that causes noise and vibration, the approximate optimum design has been investigated by means of combining a progressive quadratic response surface method (PQRSM) and a time-stepping finite element method considering drive circuit. The PQRSM is more effective than conjugate gradient method in torque ripple minimization.

Research interest in the switched reluctance motor (SRM) has grown significantly in recent years because of their apparent advantages such as simple construction, fault tolerance and mechanical robustness. In this paper, we deal with the effect of design variables on irreversible magnet demagnetization in the FRM using two-dimensional finite-element method (2-D FEM). The nonlinear characteristic of the permanent magnet is considered as well as that of a magnetic core on each B-H curve. From the analysis results, the most important geometrical dimensions are suggested in terms of irreversible magnet demagnetization.

A novel permanent magnet (PM) flux concentration type linear oscillatory actuator (LOA) for a compressor is analyzed in this paper. The characteristics of the flux concentration typed LOA, which is driven by sinusoidal and rectangular input are compared using finite element method (FEM). In this computation, the equation of magnetic field is coupled with the equation of the driving electric circuit and the equation of motion. The results are compared in respect of iron losses. The eddy current loss and hysteresis loss of both the sinusoidal input and rectangular input was calculated using 2D-FEM.

This paper introduces flux-reversal machine (FRM) and presents the design of a FRM to reduce the cogging torque. The effect of the design parameters on the characteristic and cogging torque is analyzed by finite element method (FEM). The considered design parameters are bifurcated teeth, chamfered magnet poles, chamfered rotor tooth tips and rotor skewing. As a result, we can find the optimum model reduced cogging torque and torque ripple in 6/8 FRM.

The large demagnetizing currents in a single-phase line-start permanent magnet motor are generated by a starting and locked rotor condition. Thus, irreversible magnet demagnetization occurs due to the external demagnetizing field by these currents. In this paper, we present the phenomenon of the irreversible magnet demagnetization using two-dimensional finite-element method (2-D FEM). The nonlinear analysis of a permanent magnet is added to 2-D FEM to consider irreversible demagnetization. As a result, design techniques which are effective in avoiding irreversible demagnetization are proposed.

The magnetization direction of a permanent magnet is an important variable in the design process of a brushless dc motor. This paper describes the effect of the magnetization direction on the various characteristics. Especially, we concentrate on the irreversible demagnetization characteristic of a permanent magnet. Two kinds of magnetization direction (radial and parallel direction) and finite element method are used to analyze the effect. From the simulation and experimental results, we suggest that the radial magnetization direction has more advantage in terms of the irreversible magnet demagnetization.

This article introduces a single phase flux-reversal machine (FRM) and presents the design method to improve its starting torque. The effects of the design parameters on the characteristic and starting torque are analyzed by the finite element method. The design variables considered are tapered airgap, stepped airgap, slotted teeth, and asymmetric PM width. As a result, we can find the best model in producing starting torque of a single phase 2∕3 FRM.

Flux-reversal machine (FRM) is a doubly salient stator permanent magnet (PM) machine with flux linkage reversal in the stator concentrated windings. It can operate in both motoring and generating modes. In this paper, a design technique to improve the performance of FRM is proposed. The proposed techniques have a stator winding and a magnet arrangement method. The stator and rotor shapes of concave-type and a flux barrier are also proposed. According to the experimental results, it is shown that the proposed FRM has improved the performance.