Hee-Jun Kim

Demagnetization Analysis of Permanent Magnets According to Rotor Types of Interior Permanent Magnet Synchronous Motor

This paper shows a study on the demagnetization performance analysis of permanent magnet according to three kinds of rotor types of an interior permanent magnet synchronous motor (IPMSM). It is very important to consider demagnetization performance as well as motor performance such as rated torque, output current, and efficiency when designing IPMSM. Three kinds of rotor types according to permanent magnet arrangement; single layer type, v shape type, and double layer type are generally used for IPMSM. In the paper, the magnetic equivalent circuits according to each rotor type are proposed in order for initial design of thickness of permanent magnets considering demagnetization by lumped constant related to magnetic circuit. The volume of permanent magnets per pole and back EMF of each rotor type is assumed to equal for the comparison of demagnetization of IPMSMs with same performance each other. Next, distribution of demagnetization in the permanent magnet is analyzed by using finite element method (FEM) for the verification of the results by magnetic equivalent circuit.

An improved method for anti-islanding by reactive power control

Recently, the study of the islanding phenomenon, which unfavorably maintains its operation even when the utility grid is removed, has led to the trend of utility interactive inverters in the photovoltaic generation system. In this paper, a novel anti-islanding method is presented. The proposed method can keep the real average power component constant by MPPT control and causes the load current frequency with only a change of the reactive power component under islanding conditions. Its periodical change of the reactive power component can decrease the NDZ (non-detective zone) so that the detection of various loads will be possible. Therefore, the proposed method enables islanding detection, in the worst case, no load-variation compared to before removal of the grid. It has been proven theoretically that the influence of the grid can be minimized in the case of an additional reactive power component and the islanding detection is also confirmed from the experimental results with an inverter for a 3 kW photovoltaic generation system, by applying the proposed anti-islanding method

Speed control of induction motor using genetic algorithm based fuzzy controller

The fuzzy logic controller has been focused in the field of vector control of induction motors. However, a systematic method for designing and tuning the fuzzy logic controller is not developed yet. In this paper, an auto-tuning method for fuzzy logic controller based on the genetic algorithm is presented. In the proposed method, normalization parameters and membership function parameters of a fuzzy controller are translated into binary bit-strings, which are processed by the genetic algorithm in order to be optimized for the well-chosen objective function (i.e. fitness function). To examine the validity of the proposed method, a genetic algorithm based fuzzy controller for an indirect vector control of induction motors is simulated and an experiment is carried out. The simulation and experimental results show a significant enhancement in shortening development time and improving system performance over a traditional manually tuned fuzzy logic controller. Thus, in the case of changing motor, the proposed method is superior to a traditional method in the respect of development time and system performance.

Current-controllable monostable multivibrator using OTAs

A monostable multivibrator with current-controllable pulse width and height is presented. The circuit utilizes three operational transconductance amplifiers (OTAs) as switching elements. Two of them compose a Schmitt trigger and the other forms an integrator. The theory of operation is presented and experimental results are used to verify theoretical predictions. A prototype circuit built with commercially available components exhibits less than 4.4% nonlinearity in its current-to-pulse width transfer characteristic from 200 to 1600 /spl mu/s and 20 ppm//spl deg/C temperature coefficient of width over 0/spl deg/C to 75/spl deg/C. The circuit also displays good linearity of current-to-pulse height and 1200 ppm//spl deg/C temperature coefficient of height.

A digital controlled electronic ballast using high frequency modulation method for the metal halide lamp

This paper presents a digital controlled electronic ballast for the metal halide lamp. The proposed ballast operates with the modulated driving frequency range of 20 kHz to 100 kHz in order to avoid the acoustic resonance phenomenon. It can start up the lamp by using the LC resonant circuit without external igniter and its digital controller includes some functions for soft starting, lamp fault protection, power control for dimming, overload protection and frequency modulation. In this paper, detailed digital control algorithms are described and a novel real time detection method of the acoustic resonance and the tracking algorithm for its avoidance are proposed. And the experimental results on the proto-type 150W metal halide electronic ballast with the proposed digital controller, which has been designed using erasable programmable logic devices (EPLDs), are discussed.

Current Harmonics Loss Analysis of 150-kW Traction Interior Permanent Magnet Synchronous Motor Through Co-Analysis of

In this study, the losses due to the time-harmonic current in a permanent magnet synchronous motor (PMSM) are calculated through a co-analysis of the time harmonics using a space vector pulse width modulation (SVPWM) inverter. PMSM is typically used as a control motor. The current in the PMSM contains harmonics because the inverter voltage is not sinusoidal, and as a result, losses occur. These losses have a negative effect on the synchronous motor performance, which is vulnerable to heat. Therefore, for efficiency and performance evaluation of the PMSM, it is necessary to consider a co-analysis of the time harmonics. In this study, we present a co-analysis method for a PMSM designed for buses and compare the analysis results with those of the current source analysis in order to verify the significance of the co-analysis. In particular, it is observed that the difference in the eddy current losses in the PM individually determined with the current source analysis and co-analysis is approximately 500%. For validating this study, the experimental equipment is established, and it can be confirmed that the experimental results are close to the co-analysis results.

d\hbox{-}q

With the recent interest in environment-friendly vehicles such as electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs), various topologies are being proposed for the on-board charger (OBC) required to charge the lithium battery that serves as the energy storage system. If a specific topology is selected and used, the output current of the charger is bound to contain low-frequency ripple that is twice the input power supply frequency. In this study, to analyze the effects of the low-frequency ripple on the lithium battery, a number of charging/discharging cycles are performed to apply low-frequency ripple current and constant current to PHEV lithium battery cells with similar properties. In addition, we conducted capacity test for each specific cycle to compare their performances to analyze the effects of OBCs low-frequency ripple on the battery.

Axis Current Control and Finite Element Method

An embedded inductor constructed with Sendust powder composite films and embedded circuits is proposed. The composite films consist of mixed Sendust flaked powders and EPDM rubber. An embedded circuit is an etched spiral copper trace with 16 turns and two layers. Copper trace is patterned with a dimension of 0.025 mm thickness, 0.1 mm width, and 0.1 mm pitch. Regarding the performances of the proposed inductor, it was obtained that the simulated inductance and copper resistance are 4.7 uH and 770 mΩ, respectively, while the measured results are 5.0 uH and 720 mQ, respectively. Measurements also show that the proposed inductor has relative high permeability and quality factor in a wide range of frequencies. It was confirmed that inductance of this inductor has a good stability to high frequency. To verify the usefulness of this inductor, the embedded inductor with a flexibility and the dimension of 10 mm × 7 mm × 0.3 mm was applied to a step-up dc-dc converter that is fabricated in the flexible printed circuit. The output power of the fabricated dc-dc converter is 1.8 W (4.5 V/400 mA), and the switching frequency is 1.2 MHz. Finally, the fabricated dc-dc converter was tested and the maximum efficiency of 84% was obtained.

Analytical study on low-frequency ripple effect of battery charging

This paper presents an LED lighting system with an LED color control algorithm that can independently change its color temperature and illuminance. To show the validity of the proposed algorithm, it is proven that its solution always exists. The proposed algorithm was applied to the control of an LED module that is composed of red, green, blue, and white (RGBW) LEDs. Its color temperature variation ranged from 3,500~7,500[], and its illuminance ranges from 500~1,500[lux]. Within these range, the color temperature and illuminance deviations are as low as [%] when the junction temperature of LEDs are maintained at 40[]. In the range of 30~70[], the measured illuminance and color temperature deviations are as low as 2.1[%] and 3.6[%], and the compensated ones are as low as 1[%] and 0.49[%], when the desired illuminance and color temperature are 1,000[lux] and 6,500[], respectively.nyang.ac.kr).

An Embedded Inductor Using Sendust Powder Composite Films for Step-Up DC–DC Converter

In this paper, recurrent artificial neural network (RNN) based self tuning speed controller is proposed for the high performance drives of induction motor. RNN provides a nonlinear modeling of motor drive system and could give the information of the load variation, system noise and parameter variation of induction motor to the controller through the on-line estimated weights of corresponding RNN. Thus, proposed self tuning controller can change gains of the controller according to system conditions. The gains are composed with the weights of R-NN. For the on-line estimation of the weights of RNN, extended Kalman filter (EKF) algorithm is used. Self tuning controller that is adequate for the speed control of induction motor is designed. The availability of the proposed controller is verified through the MATLAB simulation with the comparison of conventional PI controller.