• Journal of Power Electronics
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• 제18권1호
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• pp.34-44
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• 2018

This paper presents a pulse-width adjustment (PWA) strategy for a novel bidirectional DC-DC boost converter to improve the performance of the dynamic inductor current response. This novel converter consists of three main components: a full-bridge converter (FBC), a high-frequency isolated transformer with large leakage inductance, and a three-level voltage-doubler rectifier (VDR). A number of scholars have analyzed the principles, such as the soft-switching performance and high-efficiency characteristic, of this converter based on pulse-width modulation plus phase-shift (PPS) control. It turns out that this converter is suitable for energy storage applications and exhibits good performance. However, the dynamic inductor current response processes of control variable adjustment is not analyzed in this converter. In fact, dc component may occur in the inductor current during its dynamic response process, which can influence the stability and reliability of the converter system. The dynamic responses under different operating modes of a conventional feedforward control are discussed in this paper. And a PWA strategy is proposed to enhance the dynamic inductor current response performance of the converter. This paper gives a detailed design and implementation of the PWA strategy. The proposed strategy is verified through a series of simulation and experimental results.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.678-683
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• 2000

The one-dimensional performance model of a torque converter has been widely used to analyze and predict the performance and dynamic behavior of a torque converter. But this model doesn't include the information of the operating fluid properties. Therefore, to precisely predict dynamic performance of a torque converter, the effect of operating conditions must be considered through experimental coefficients such as friction loss coefficient and shock loss coefficient. And these coefficients cannot be achieved without experiments or internal flow analysis. In this study, the effects of varying material properties of operating fluid according to various operating temperatures are clarified with flow analysis of a torque converter. And these results are verified by comparing with those of performance experiment.

• 한국자동차공학회논문집
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• 제10권1호
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• pp.244-254
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• 2002

To enhance the acceleration performance and fuel consumption rate of a vehicle, the torque converter is modified or newly-developed with reliable analysis model. Up to recently, the one dimensional performance model has been used for the analysis and design of torque converter. The model is described with constant parameters based on the concept of mean flow path. When it is used in practice, some experiential correction factors are needed to minimize tole estimated error. These factors have poor physical meaning and cannot be applied confidently to the other specification of torque converter. In this study, the detail dynamic model of torque converter is presented to establish the physical meaning of correction factors. To verify the validity of model, performance test was carried out with various input speed and oil temperature. The effect of oil temperature on the performance is analysed, and it is applied to the dynamic model. And, to obtain the internal flow pattern of torque converter, CFD(Computational Fluid Dyanmics) analysis is carried out on three-dimensional turbulent flow. Correction factors are determined from the internal flow pattern, and their variation is presented with the speed ratio of torque converter. Finally, the sensitivity of correction factors to the speed ratio is studied for the case of changing capacity factor with maintaining torque ratio.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.558-564
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• 2001

General vehicle is evaluated by its acceleration, fuel economy, NVH (Noise, Vibration and Harshness) and subjective (Launching feel) performance. The first step to enhance its performance is to know how much each component affects on the vehicle performance. It is very important to know what is the key factor of the component among many specifications. Hydraulic torque converter can be expressed by means of its performance curve (torque ratio and capacity factor). In this paper, the key factor of torque converter, which affect vehicle performance, are explored by using Taguchi method.

• 대한기계학회논문집A
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• 제21권3호
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• pp.369-377
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• 1997

The torque converter, a major part of automatic transmissions, has many difficulties in analysis due to the factors such as power transmission through fluid flow, complex internal geometry, and various operating conditions. Because of such difficulties, the dynamic analysis and design of a torque converter are generally carried out by using equivalent performance model which is based on the concept of mean flow path. Since the design procedures of a torque converter are essential technology of automotive industry, the details of the procedures are rarely published. In this study, the basic design procedures of a torque converter are systemized and coded based on the equivalent performance model. The mathematical methods to deal with mean flow path determination and the core-shape are developed. And by using this model, the method of determination of performance parameters satisfying the requested performance is proposed. Finally, to embody the three-dimensional shape, the intermediate blade angles which maximize the tractive performance are determined and laid out.

• 전기학회논문지
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• 제67권12호
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• pp.1729-1734
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• 2018

Recently, interest in environmentally friendly transportation systems has been increasing, and study on railway systems has been aggressively conducted. Therefore, lots of studies have been done in railway advanced countries to improve performance of PWM converter. The research on the PWM converter for railway vehicle was mainly carried out on the converter mounted on railway vehicle such as the high-speed railway and metropolitan railway. In also, a lot of study has been carried out to improve converter performance installed in the ground. The high-capacity transform used in this paper converted from AC 22.9kV to AC 590V. The converter changed from AC 590V to DC 950V. In general, in the case of rectifier, the DC power supply system has a negative impact on inverter control characteristics because it can not avoid the pulsating component. In this study, it was performed current control for high-capacity converter using Matlab Simulink. The PWM converter is normally performed through the voltage and current at starting mode, powering mode, and braking mode. In the light-load test and the on-line test, we have studied for the PWM converter characteristics. Using this research, we have founded that the converter has excellent performance.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.485-488
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• 2000

In this paper dynamic analyses and control design of a step-down switched-capacitor dc-dc converter are presented. Open-loop dynamics of the converter are analyzed using the stage-space averaging technique. A systmatic control design method that offers excellent closed-loop performance for the converter is proposed, The analysis results and dynamic performance of the converter are verified using 18 W experimental converter that delivers a 5V/3.5V output from a 11-16V input source.

• 대한기계학회논문집A
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• 제26권6호
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• pp.1085-1091
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• 2002

General vehicle is evaluated by its acceleration, fuel economy, NVH (Noise, Vibration and Harshness) and subjective (such as launching feel) performance. The first step to enhance its performance is to know how much each component affects on the vehicle performance. It is very important to know what is the key factor of the component among many specifications. Hydraulic torque converter can be expressed by means of its performance curve (torque ratio and capacity factor). In this paper, the key factor of torque converter, which affect vehicle performance, are explored by using Taguchi method. Moreover, general sensitivity analysis method is compared with Taguchi's experiment.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.31-31
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• 2000

In this paper, Ive design and test the V/F converter for KSR-III INS using commertial INC, VFC110, AD652. The test result shows that performance of AD652 is better than that of VFC110. Through the calibration of V/F converter, we show that the designed V/F converter has a good performance and is usable for KSR-III.

• Journal of Power Electronics
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• 제7권4호
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• pp.310-317
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• 2007

In this paper, an analysis and hysteretic controller design of a $3^{rd}$ order buck converter is presented. The proposed hysteretic controller consists of an inner current-loop, just like the conventional cascade control scheme, and an outer voltage-loop for load voltage regulation. Although it is possible to include an inner current loop from different branches of the converter, from the feasibility and operational point of view, the load side capacitor current would be the better choice. The addition of an inner current-loop improves the dynamic performance of the converter while preserving the robustness of the hysteretic control. The controller formulation and closed-loop converter performance analysis are validated through computer simulations. Few experimental results of the proposed converter are given and compared with the buck converter.