Sung-An Kim

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.

Modeling of Non-Linear Analysis of Dynamic Characteristics of Linear Compressor

This paper proposes considering nonlinear dynamic characteristics method stroke of linear compressor and comparison with experimental results. Pressure on stroke and current function is shown as springs and dampers. And inductance and the motor constant are mathematical modeled as a function of the stroke and the current for a flux linkage. Dynamics characteristics were interpreted through mathematical modeling.

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.

Optimal rotor shape design of 3-step skew spoke type BLAC motor to reducing cogging torque

In electric power steering (EPS), spoke type brushless ac (BLAC) motors offer distinct advantages over other electric motor types in terms of torque smoothness, reliability and efficiency. This paper deals with the shape optimization of spoke type BLAC motor, in order to minimization cogging torque. In this paper examines, 3 step skewing rotor angle, optimizing rotor core edge and rotor overlap length for minimize cogging torque in spoke type BLAC motor. The methods were applied to existing machine designs and their performance was calculated using finite- element analysis (FEA). Prototypes of the machine designs were constructed and experimental results obtained. It is shown that the FEA predicted the cogging torque to be nearly reduce using those method.

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 rotor shape design for minimizing cogging torque of spoke type BLAC motor for EPS

In electric power steering (EPS), spoke type brushless ac (BLAC) motors offer distinct advantages over other electric motor types in terms torque smoothness, reliability and efficiency. This paper deals with the shape optimization of spoke type BLAC motor, in order to reduce cogging torque. This paper examines 3 steps skewing rotor angle, optimizing rotor core edge and rotor overlap length for reducing cogging torque in spoke type BLAC motor. The methods were applied to existing machine designs and their performance was calculated using finite-element analysis (FEA). Prototypes of the machine designs were constructed and experimental results obtained. It is shown that the FEA predicted the cogging torque to be nearly reduce using those methods.

A Studies for Sequential Mode Change Control Algorithm of the Parallel Dual Converter of Using Thyristor for Supplying the Urban Railway DC Power

This paper is proposed control algorithm for the using thyristor of the parallel dual converter for Urban railway power supply in order to return the regenerative power generated by regenerative braking in urban railway train. Conventional control algorithm of Thyristor dual converter for urban railway power supply has voltage variation within a control range of hysteresis band. The purposed control algorithm of the parallel thyristor dual converter is to maintain a constant voltage without voltage variation in accordance with variable load through the Sequential mode change. And the control algorithm need calculating optimum initial firing angle to consider magnitude of the load current slope. For this purpose, Proposed algorithm for sequential conversion mode of the dual converter was verified by applying for the simulation.

Twelve Step Control of Brushless DC Motor Sensorless Drive System to Reduce Torque Ripple using Voltage Compensation

This paper presents a brushless DC motor sensorless drive system using a twelve step control. The twelve step control has the two phase excitations and three phase excitations. For the twelve step control, the torque ripple is caused by the conversion section between the three phase excitations and two phase excitations. The torque ripple generates a mechanical vibration and acoustic noise. To solve the problem, this paper proposes a voltage compensation control to reduce the torque ripple. The simulation and experimental results verify that the proposed control can reduce the torque ripple significantly.

Improved parallel operation mode control of parallel connected 12-pulse thyristor dual converter for urban railway power substations

Parallel-connected 12-pulse thyristor dual converters are connected to the up/down trolley line in urban power substations. When there are high-traffic trains on the up trolley line or the down trolley line, the electric energy, i.e., energy consumed and regenerative energy, increases. During this time, two converters are connected in parallel to supply power or feed energy back to the distribution grid. A parallel operation control scheme has two operating modes depending on the energy flow of trains. When the energy is less than the rated power of a converter, only one converter operates in a single operation mode. If the energy exceeds the rated power of a converter, the other converter is operated in parallel mode operation to distribute the excess energy. During the switching from the single operation mode to the parallel operation mode, overshoots and undershoots occur in the DC trolley voltage and current of each converter due to the large error in the PI controller. To solve these problems, this study proposes improved control method to prevent large overshoots and undershoots. The effectiveness of this proposed control is verified by simulation and experiment based on the comparison of the performance of conventional and proposed control method.