Sang-Geon Lee

Optimal Structure Design for Minimizing Detent Force of PMLSM for a Ropeless Elevator

This paper presents the optimal structure design and magnetic force analysis of a ropeless elevator model that employs permanent magnet linear synchronous motors (PMLSMs) with the structure of a double-sided long-stator. To obtain the optimal structure, the combination of response surface methodology and 2-D finite element analysis, which can solve the problem effectively without consuming much time, is utilized to estimate the design parameters of PMLSM. The numerical calculations and the experimental results are reported to validate the applicability of this double-sided long-stator type PMLSM for a ropeless elevator system.

Electromagnetic Normal Force Characteristics of a Permanent Magnet Linear Synchronous Motor with Double Primary Side

The large normal force of the permanent magnet linear synchronous motor (PMLSM) is caused by the PM group shifting. This is the significant drawback which will deteriorate the performance of the drive system in high-precision applications. In the optimization design process, when the PM group shifting length is not zero the normal force will be changed into a pulsation curve with large amplitude. To solve this problem, this paper proposes that the PMLSM is divided into two symmetrical PMLSMs. The effectiveness of this proposed structure is verified by the simulation and experiment according to the comparison of the electromagnetic force characteristics between the conventional and proposed structures.

Optimal design of slotted iron core type permanent magnet linear synchronous motor for ropeless elevator system

This paper investigates an optimal design of a double-sided slotted iron core type permanent magnet linear synchronous motor (PMLSM) using for ropeless elevator system. To obtain the optimal structure, the combination of response surface methodology (RSM) and two dimensional (2D) finite element analysis (FEA), which can solve the problem effectively without much time consuming, is utilized to investigate the PMLSM characteristics. Moreover, the detent force is more detailed analyzed with the manufacturing consideration. In final some numerical calculation results are reported to validate the applicability of this double-sided slotted iron core type PMLSM in ropeless elevator system.

Topology structure selection of permanent magnet linear synchronous motor for ropeless elevator system

To make the ropeless elevator system become practical, one of the most important requirements is the high force density. The slotted iron core type permanent magnet linear synchronous motor (PMLSM) seems to be the best choice except the large detent force. Therefore, in this paper we will investigate the characteristics of detent force, normal force, and thrust of PMLSM under different motor topology structures. Finally, the long stator double-sided slotted iron core type PMLSM with fractional slot winding is selected for the best performance.

Hall effect sensor based space vector PWM control of permanent magnet synchronous machine

This paper proposes a space vector control of permanent magnet synchronous machine (PMSM) based on Hall effect sensor, which is very useful in practical applications due to the exactly same hardware structures between PMSM and brushless DC (BLDC) machine. This proposed method can be considered as an intermediate stage of development between the general incremental encoder based and sensorless based PMSM control methods. Because 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. Finally the high performance of this proposed method is validated by some experimental results.

A novel twelve-step sensor-less control for torque ripple reduction in brushless DC motor

The large torque ripple and decrease of the output torque of brushless DC motor (BLDCM) with sinusoidal back EMF are caused by the current commutation between two phases of the motor. It is the six step 120° drive that is suitable for the motor with an ideal trapezoidal back EMF. This is the significant drawback which will deteriorate the performance of the drive system in high performance and high efficiency applications. To solve the problem, this paper proposes the novel algorithm using novel twelve step sensor-less control to reduce torque ripple and increase of the output torque of BLDCM with sinusoidal back EMF. The proposed algorithm has two commutation process. In the two phase conducting period, rotor position is estimated to control speed of BLDCM. In the three phase conducting period, the slope of duty ratio considering the phase current variation ratio is applied from the calculations of no load duty and load duty according to speed and load conditions of BLDCM. The theoretical basis of the algorithm and individual definition of the control block is explained. The effectiveness of this proposed control is verified by the simulation and experiment according to the comparison of the output characteristics between the traditional and proposed control.

Minimization of Cogging Torque in Fractional-Slot Axial Flux Permanent Magnet Synchronous Machine with Conventional Structure

This paper studies minimization of cogging torque in fractional-slot winding axial flux PM machines without skewing rotor magnets or displacing stator slots. Fractional winding has small cogging torque which is highlight for applications such as wind turbines. Cogging torque is caused by interaction between rotor magnets and stator core. The axial flux PM machine has an unique structure that the slot dimensions is usually constant and by varying slot opening and pole arc ratio, cogging torque could be minimized. In this paper, cogging torque of fractional-slot concentrated winding was further reduced by proposed method.

Structure analysis of axial flux permanent magnet synchronous machine for wind generators

This paper presents the structure design and analysis of inner-rotor type axial-flux permanent magnet synchronous machines(AFPMs). The major sources of vibration in electric machines such as motors and generators are electric magnetic force distributed on both stators. The rotor suffers from unbalanced magnetic force when air gas are not symmetric on dual sides. In this paper, natural frequencies, mode shapes, and deformation were studied at normal and fault operations.

Boost and flux-weakening control of engine direct connection type ipmsg over wide-speed range

This paper proposes a boost and flux-weakening control (BFWC) of engine direct connection type interior permanent magnet synchronous generator (IPMSG) over wide-speed range. Since the speed and the load of engine direct connection type IPMSG are rapidly changing, the constant dc link voltage control of power generation system is required. Therefore, two different implementations are considered: when the speed of IPMSG is less than base speed, boost control method is applied to maintain a constant DC link voltage by the direct torque and flux control (DTFC) within the current and voltage constraints. And, when exceeding the base speed, flux-weakening control method is applied to suppress the dc link voltage rises. In addition, a feed-forward controller is applied to improve the dynamic characteristics of maximum torque per ampere/voltage (MTPA/V) and flux-weakening operations. The feasibility of the proposed method is verified under various operating conditions with computer simulation and testing with the 3.5 kW IPMSG power generation system.

Optimal design of permanent magnet linear synchronous motor for ultra low force pulsations

The inherent drawback of iron-core type permanent magnet linear synchronous motor (PMLSM) is detent force that is dependent on several major factors such as pole-arc to pole-pitch ratio of magnet, slot clearance, and skewing. To minimize the detent force, this paper proposes a structure optimization using the combined computation of two dimensional (2-D) finite element method (FEM) and response surface methodology (RSM). The RSM, that is a collection of the statistical and mathematical techniques, is utilized to predict the global optimal solution based on the FEM calculated results of the detect forces for different combinations of factors. With the help of the combined computation the high capacity iron-core type PMLSM with more than 12000 N propulsion forces only contains less than 3 N detent forces.