• Journal of Electrical Engineering and Technology
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• v.8 no.5
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• pp.1086-1095
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• 2013

The main issue of parallel three-phase boost converters is reduction of the low- and high frequency circulating currents. Most present technologies concentrate on low frequency circulating current because the circulating current controller cannot mitigate the high frequency circulating current. In this paper, analytical approach of three-phase coupled inductor applied to parallel system becomes an important objective to effectively reduce the low- and high frequency circulating currents. The characteristics of three-phase coupled inductor based on a structure and voltage equations are mathematically derived. The modified voltage equations are then applied to parallel three-phase boost converters to develop averaged models in stationary coordinates and rotating coordinates. Based on the averaged modeling approach, design of the circulating current controller is presented. Simulation and experimental results demonstrate the effectiveness of the analysis and modeling for the parallel three-phase boost converters using three-phase coupled inductor.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.5
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• pp.350-357
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• 2020

This study presents the design of an 18 kW two-phase interleaved buck converter that uses a coupled inductor for an electric vehicle rapid charger. The designs of a two-phase coupled inductor for current ripple and physical size reduction and a two-phase interleaved buck converter based on silicon carbide metal - oxide - semiconductor field-effect transistor for high efficiency were described in detail. The operating principle of the two-phase interleaved buck converter was analyzed, and the coupled inductor was investigated using a magnetized equivalent circuit. Simulation and experiments were conducted to verify the validity of the proposed two-phase interleaved buck converter, and the theoretical design method and experimental results were confirmed.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.3
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• pp.250-257
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• 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
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• v.11 no.1
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• pp.16-20
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• 2011

This paper presents a zero-voltage-switching (ZVS) boost converter using a coupled inductor. It utilizes an additional winding to the boost inductor and an auxiliary diode. The ZVS characteristic of the proposed converter reduces the switching losses of the active power switches and raises the power conversion efficiency. The principle of operation and a system analysis are presented. The theoretical analysis and performance of the proposed converter were verified with a 100W experimental prototype operating at a 107 kHz switching frequency.

• Journal of Power Electronics
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• v.15 no.2
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• pp.327-337
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• 2015

This study discusses the design of a parallel-operated DC-DC single-ended primary-inductor converter (SEPIC) for low-voltage application and current sharing with a constant output voltage. A coupled inductor is used for parallel-connected SEPIC topology. Generally, two separate inductors require different ripple currents, but a coupled inductor has the advantage of using the same ripple current. Furthermore, tightly coupled inductors require only half of the ripple current that separate inductors use. In this proposed work, tightly coupled inductors are used. These produce an output that is more efficient than that from separate inductors. Two SEPICs are also connected in parallel using the coupled inductors with a single common controller. An analog control circuit is designed to generate pulse width modulation (PWM) signals and to fulfill the closed-loop control function. A stable output current-sharing strategy is proposed in this system. An experimental setup is developed for a 18.5 V, 60 W parallel SEPIC (PSEPIC) converter, and the results are verified. Results indicate that the PSEPIC provides good response for the variation of input voltage and sudden change in load.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.6
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• pp.481-487
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• 2014

This study proposes a two-phase non-inverting buck-boost converter that uses a coupled inductor. The multi-phase converter has many advantages over single-phase counterparts, such as reduced output current ripple and conduction loss in switching devices and passive elements. Although the output current ripple of the multi-phase converter is reduced significantly because of the interleaved effect, the inductor current ripple is not reduced in multi-phase converters. One of the solutions to this problem is to use a coupled inductor. A 4 kW prototype converter is built and tested to verify the performance of the proposed converter.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.1
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• pp.37-43
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• 2020

This study proposes a 7kW low-voltage DC-DC converter (LDC) using a coupled inductor (CI) for heavy hydrogen electric transport vehicles. The LDC uses a phase-shift manner for soft switching. SiC-MOSFET is used to reduce the loss of reverse recovery current through the use of a high switching frequency. LDC is require large transformer and inductor because of large output current. The size of transformer and inductor can be reduced by deviding the transformer and inductor into two pieces each. This work presents the experimental results of the proposed circuit.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.335-336
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• 2014

This paper investigates the design of coupled inductor for minimum inductor current ripple in rapid traction battery charger systems. Based on the general circuit model of 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, i.e. a complete inverse coupling without leakage inductance, as the steady-state duty ratio operating point approaches 0.5. 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. Coupled inductors having optimal coupling factor can minimize the ripple current of inductor and battery current resulting in a reliable and efficient operation of battery chargers.

• Journal of IKEEE
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• v.23 no.1
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• pp.68-73
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• 2019

This paper presents a novel fast shut-down scheme for Buck converter by using a coupled inductor. Generally, a controller for Buck converter stops generating PWM patterns in various fault cases: Overcurrent, Short circuit, or Overvoltage, but the inductor and capacitor keep supplying their stored energy to loads although the switching operations in Buck converter stopped. The stored energy in the inductor and capacitor could cause electrical stresses on breakers and safety problems. The main idea of the proposed fast shutdown scheme is to demagnetize the inductor core by using a coupled inductor, and its performance and operations are verified by using PSIM Simulation.

• Journal of Power Electronics
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• v.16 no.2
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• pp.436-446
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• 2016

A novel step-up DC-DC converter with a switched-coupled-inductor-capacitor (SCIC) which successfully integrates three-winding coupled inductors and switched-capacitor techniques is proposed in this paper. The primary side of the coupled inductors for the SCIC is charged by the input source, and the capacitors are charged in parallel and discharged in series by the secondary windings of the coupled inductor to achieve a high step-up voltage gain with an appropriate duty ratio. In addition, the passive lossless clamped circuits recycle the leakage energy and reduce the voltage stress on the main switch effectively, and the reverse-recovery problem of the diodes is alleviated by the leakage inductor. Thus, the efficiency can be improved. The operating principle and steady-state analyses of the converter are discussed in detail. Finally, a prototype circuit at a 50 kHz switching frequency with a 20-V input voltage, a 200-V output voltage, and a 200-W output power is built in the laboratory to verify the performance of the proposed converter.