• Proceedings of the KIPE Conference
• /
• 2017.07a
• /
• pp.88-89
• /
• 2017

This paper investigates the design of multi-winding coupled inductor for minimum inductor current ripple in rapid traction battery charger systems. Based on the general circuit model of multi-winding coupled inductor together with the operating principles of dc-dc converter, the relationship between the ripple size of inductor current and the coupling factor is derived under the different duty ratio. The optimal coupling factor which corresponds to a minimum inductor ripple current becomes -(1/n-1), i.e. a complete inverse coupling without leakage inductance, as the steady-state duty ratio operating point approaches 1/n, 2/n, … or (n1)/n. In an opposite manner, the optimal coupling factor value of zero, i.e. zero mutual inductance, is required when the steady-state duty ratio operating point approaches either zero or one.

• Journal of Power Electronics
• /
• v.17 no.3
• /
• pp.621-631
• /
• 2017

A KY converter integrated with a conventional synchronously rectified (SR) boost converter and a coupled inductor is presented in this paper. This improved KY converter has the following advantages: 1) the two converters use common switches; 2) the voltage gain of the KY converter can be improved due to the integration of a boost converter and a coupled inductor; 3) the leakage inductance of the coupled inductor is utilized to achieve zero voltage switching (ZVS); 4) the current stress on the charge pump capacitors and the decreasing rate of the diode current can be limited due to the use of the coupled inductor; and 5) the output current is non-pulsating. Moreover, the active switches are driven by using one half-bridge gate driver. Thus, no isolated driver is needed. Finally, the operating principle and analysis of the proposed converter are given to verify the effectiveness of the proposed converter.

• Proceedings of the KIPE Conference
• /
• 2010.07a
• /
• pp.470-471
• /
• 2010

In this paper, the coupled inductor with three branches in two interleaved converter are analyzed to effectively suppress the high frequency circulating current since the circulating current controller cannot mitigate the high frequency circulating current. As a result, the novel averaged model including the coupled inductor with zero sequence components is developed for reducing the low and high frequency circulating current simultaneously.

• Journal of Power Electronics
• /
• v.17 no.2
• /
• pp.389-397
• /
• 2017

A control scheme for stand-alone inverters that utilizes an inductor current observer (ICO) is proposed. The proposed method measures disturbance load currents using a current sensor and it estimates the inductor current using the ICO. The filter parameter mismatch effect is analyzed to confirm the ICO's controllability. The ICO and controllers are designed in a continuous-time domain and transferred to a discrete-time domain with a digital delay. Experimental results demonstrate the effectiveness of the ICO using a 5-kVA single-phase stand-alone inverter prototype. The experimental results demonstrate that the observed current matches the actual current and that the proposed method can archive a less than 2.4% total harmonic distortion (THD) sinusoidal output waveform under nonlinear load conditions.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.19 no.3
• /
• pp.290-296
• /
• 2014

This paper presents a design strategy for the control of the Z-source inverter (ZSI). For the Z-network capacitor voltage control, the average current model is derived to describe the dynamics of the voltage control and the controller outputs the average current command for the capacitor. Z-network inductor current reference is derived from the average current model of the Z-network capacitor. The inner current control loop outputs the average voltage command for the Z-network inductor and the shoot-through duty ratio of the ZSI is calculated from the output using the average voltage model of the Z-network inductor. The gain values of the current and voltage controllers are directly obtained by the Z-network parameters and desired bandwidth of each controller without a gain tuning process.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.6
• /
• pp.2553-2560
• /
• 2018

In Korea, there are no instances where a hydrogen fuel cell power generation system has been used in a railway vehicle. Only the basic topology has been studied. In the previous study, conventional converters using a single switch were applied to the fuel cell power generation system. Therefore, current stress on the switch at converter on-off transitions would be large when controlling a large-capacity railway vehicle. In addition, since the input side ripple is also large, there is a problem with a shortening of the lifetime of both the fuel cell power generation system and the inductor. In this paper, a soft-switching transformer inductor boost converter for fuel cell powered railway vehicles was proposed. A technique to reduce both the switching current stress generated during on-off transitions, and the input ripple current flowing in the inductor were studied. The soft-switching TIB converter uses a transformer-type inductor to configure the entire circuit in an interleaved method, and reduces both input current ripple and the current ripple of the inductor and switch.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2004.05a
• /
• pp.506-510
• /
• 2004

A multi-phase interleaved buck converter is used to reduce current ripples and filter size of a power supply. This paper addresses the modelling and steady-state analysis of the multi-phase interleaved buck converter operated in discontinuous inductor current mode. The model is derived using an averaging technique in steady state. The do voltage ratio and the range of the discontinuous inductor current mode(DICM) and the continuous output current mode(COCM) are derived from the averaged state-space model. In addition, the efficiency is investigated according to the number of phase.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.16 no.3
• /
• pp.250-257
• /
• 2011

This paper analyzes characteristic of the three-phase coupled inductor connected to ac source to effectively mitigate the high-frequency circulating current generated in parallel three-phase boost converters. The three-phase coupled inductor analysis presented in this paper uses the three-phase coupled inductor structure and voltage equations. Based on this analysis, the three-phase coupled inductor is added to the conventional low-frequency averaged model. As a result, the novel averaged model which can reduce the low and high-frequency circulating current simultaneously is developed. Using the zero-sequence component of the novel averaged model, each total inductance to the circulating current of the three-phase coupled inductor and line inductor can be obtained. Simulation and experiment results verify the usefulness of three-phase coupled inductor in parallel three-phase boost converters.

• Journal of Power Electronics
• /
• v.13 no.4
• /
• pp.636-646
• /
• 2013

A single-phase tapped-inductor boost converter has been proposed previously. However, detailed characterization and performance analysis were not conducted. This paper presents a detailed characterization, performance analysis, and design expressions of a single-phase tapped-coupled-inductor boost converter. Expressions are derived for average and RMS input current as well as for RMS input and output capacitor current ripple. A systematic approach for sizing the tapped-coupled inductor, active switch, and output diode is presented; such approach has not been reported in related literature. This study reveals that sizing of the inductor has to be based on current ripple requirement, turns ratio, and load. Conditions that produce discontinuous inductor current are also discussed. Analysis of a non-ideal converter operating in continuous conduction mode is also conducted. The expression for the voltage ratio considering the coupling coefficient is derived. The suitability of the converter for high-voltage step-up applications is evaluated. Factors that affect the voltage boost ratio are also identified. The effects of duty ratio and load variation on the performance of the converter are also investigated. The theoretically derived characteristics are validated through simulations. Experimental results obtained at a low power level are included to validate the analytical and simulation results. A good agreement is observed among the analytical, simulation, and experimental results.

• Proceedings of the IEEK Conference
• /
• 2003.07c
• /
• pp.2935-2938
• /
• 2003

A new Valley-fill circuit for improving PF(power factor) is proposed in this paper. The proposed topology combines Valley-fill rectifier and an additional inductor for boosting. In the proposed circuit, a shapc of input current is related to the PWM duty cycle. The boosting inductor makes improve PF by the electric charge transfer action. The operation principle and the shape of input current arc analyzed as applied the boosting inductor. The optimum value of boosting inductor is determined. A 100W single-stage converter has been designed and tested. Experimental results are presented to verify the validity of the proposed converter.