Kyu-yun Hwang

Rotor Pole Design in Spoke-Type Brushless DC Motor by Response Surface Method

This paper proposes a novel rotor pole shape which consists of a uniform surface and an eccentric surface to make a sinusoidal magnetic flux density in air gap in order to reduce cogging torque, torque ripple, and harmonics of back-electromotive force waveform in spoke-type brushless DC motor. In the process of design and analysis, response surface methodology and the 2-D finite-element method are employed to obtain the rotor geometry and verify the results of the novel rotor pole shape

A Study on Optimal Pole Design of Spoke-Type IPMSM With Concentrated Winding for Reducing the Torque Ripple by Experiment Design Method

An optimal design procedure is proposed to effectively reduce the torque ripple by optimizing the rotor pole shape of the spoke-type IPMSM with concentrated winding. The procedure is composed of two steps. In step 1, the steepest descent method (SDM) is used with only two design variables to rapidly approach the optimal shape. From the near optimal rotor shape as a result of the step 1, the design variables are reselected, and the drawing spline curves are utilized to explain more complex shape with the Kriging model in step 2. By using an optimal design procedure, we show that the optimized rotor pole shape of the spoke-type IPMSM effectively reduces the torque ripple while still maintaining the average torque.

Optimization of Two-Phase In-Wheel IPMSM for Wide Speed Range by Using the Kriging Model Based on Latin Hypercube Sampling

This paper introduces an optimal design process for in-wheel interior permanent magnet synchronous motor (IPMSM) to achieve wide speed range. A finite element method (FEM) was used for calculating the inductances of the d-axis and q-axis by changing the structure of rotor shape in IPMSM. After FEM analysis, optimal design process to find optimal rotor shape is processed for wide speed range. In optimal process, the Kriging method based on the Latin hypercube sampling (LHS) and a genetic algorithm (GA) are applied due to suitability to non-linear data. Using this optimal design process, an optimal rotor shape is obtained. The optimal model has an increased wide speed range with reduced cogging torque.

An Improved Flux Observer for Sensorless Permanent Magnet Synchronous Motor Drives with Parameter Identification

This paper investigates an improved stator flux linkage observer for sensorless permanent magnet synchronous motor (PMSM) drives using a voltage-based flux linkage model and an adaptive sliding mode variable structure. We propose a new observer design that employs an improved sliding mode reaching law to achieve better estimation accuracy. The design includes two models and two adaptive estimating laws, and we illustrate that the design is stable using the Popov hyper-stability theory. Simulation and experimental results demonstrate that the proposed estimator accurately calculates the speed, the stator flux linkage, and the resistance while overcoming the shortcomings of traditional estimators.

Optimization of novel flux barrier in interior permanent magnet-type brushless dc motor based on modified Taguchi method

This paper proposes the novel flux barrier by using the modified Taguchi method to reduce the cogging torque. In the optimizing process the modified Taguchi method is utilized to consider multiple objective quality characteristics simultaneously such as the torque ripple and the efficiency as well as the cogging torque. The optimal novel flux barrier can effectively reduce the cogging torque and torque ripple and it is verified through the experimental results.

A Study on the Novel Coefficient Modeling for a Skewed Permanent Magnet and Overhang Structure for Optimal Design of Brushless DC Motor

A novel coefficient modeling technique, using a coefficient estimation method, is introduced for a brushless DC (BLDC) motor with a skewed permanent magnet and overhang structure. To construct the novel coefficient, the 3-D FEM and a design of experiment (DOE) are utilized along with the moving least square method (MLSM). Also, to verify the accuracy of the novel coefficient modeling, the conventional coefficient modeling using LSM is constructed and compared. Then the novel coefficient is combined with an approximate model constructed by 2-D FEM for use with an optimal design algorithm. For the searching process to obtain an optimal point, the genetic algorithm (GA) is used. Three-dimensional FEM simulation is used to verify the accuracy of the novel coefficient for the optimal design.

Maximum torque control for optimal design to reduce cogging torque in spoke type interior permanent magnet synchronous motor

This paper proposes the optimal design process to effectively reduce the cogging torque considering the torque and efficiency in constant torque region and constant power region by maximum torque control in spoke type interior permanent magnet synchronous motor (IPMSM). For an increase in torque and efficiency in constant power region, the saliency ratio is increased more than initial model. The two points, 2000 rpm (rated speed) in the constant torque region and 4000 rpm (double rated speed) in the constant power region, are chosen for comparing the torque and efficiency with the initial model. The maximum torque control is composed of maximum torque per ampere (MTPA) control in constant torque region and flux weakening (FW) control in constant power region. In the optimal design process, the d- and q- axis inductances at each current angle are extracted by finite element method (FEM) for MTPA and FW control. The FEM is used to calculate the cogging torque. And then, radial basis function (RBF) and genetic algorithm (GA) are used. The results showed an increase in the efficiency and torque compare to the initial model, and also the cogging torque is decreased more than initial model.

Optimal rotor design for reducing the partial demagnetization effect and cogging torque in spoke type PM motor

This paper proposes an optimized rotor pole shape that can effectively reduce the partial demagnetization effect and cogging torque. First, for reducing the peak amplitude of the external field that directly affects the partial demagnetization on the permanent magnets in spoke-type permanent magnet motor, we conduct a variation of core shape and insertion of a barrier. Second, with the rotor shape obtained by the first processes for reducing the partial demagnetization effect, another part of the rotor pole is varied to make better sinusoidal distributed air gap flux density to reduce the cogging torque. In the process of designing the rotor pole shape, a steepest descent method and a response surface method are applied for improving convergence. By using the finite element method, we show that the optimized rotor pole shape drastically reduces the effect of the partial demagnetization and cogging torque.

Optimal design of distributed winding axial flux permanent magnet synchronous generator for wind turbine systems

In order to reduce harmonic distortion, this paper presents a distributed winding type axial flux permanent magnet synchronous generator (AFPMSG), suitable for wind turbine generation systems. The characteristic analysis is performed with the aid of a 3D finite element method (FEM) and these analysis results are confirmed by the experimental results. To improve the output power and unbalance of the phase back EMF, the optimal design process by using Kriging combined with latin hypercube sampling (LHS) and genetic algorithm (GA) was utilized. As a result, the output power and unbalance of the phase back EMF of the distributed winding type AFPMSG were improved efficiently while maintaining the total harmonic distortion (THD) and the average of the phase back EMF.

Optimal design of brushless DC motor by utilizing novel coefficient modeling for skewed PM and overhang structure

A novel coefficient modeling for skewed PM and overhang structure as a coefficient estimation method is introduced for optimal design in the 2D region for a PM motor. The novel model is constructed using 3D FEM and a response surface method (RSM) based on moving least square method (LSM). Then the novel model is coupled with an additional approximated model for optimal design in the 2D region. Finally, by combining the novel model and evolution algorithm (EA), an optimal design is performed. The usefulness of the proposed design is verified by 3D FEM simulation results.