• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.369-372
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• 1994

In this paper, a voltage type dual PWM converter which achives the bidirectional power flow between a AC supply and a DC bus voltage is described. In PWM modulator, there exist a time difference between the sampling time and carrier wave, it achieves stable modulation even the disturbance in the synchronous AC source voltage. And this paper proposes the compensation method and the control method related a disturbance of synchronous signal using the low pass filter and phase shifter for the stable modulation. As a result the voltage type dual PWM converter makes the imput current wave as sinusoid, and performs the high power factor driving.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.530-533
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• 2001

Interleaved Dual Boost(IDB) converter can reduce current ripple, switching loss and harmonics without filter in input power line. Moreover, this improve power factor. In this paper, we will use the state average methode and small signal analysis at the Interleaved dual boost converter. 4-type controllers were designed by using control transfer function. The result of these controller simulations is analyzed and proposed a proper controller at IDB

• International Journal of Automotive Technology
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• v.3 no.1
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• pp.33-40
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• 2002

Increasingly stringent emission regulations of EU and CARB (California Air resource Board) require mandatory OBD (On Board Diagnostics) far the catalytic converters of a vehicle. It demands that MIL(Malfunction Indication Light) should be tuned on to inform the driver of catalytic converter failures. Currently dual oxygen sensor method Is widely used for the converter OBD. However, since it works only alter converter light-off, it has a serious limitation when applied to TLEV or more stringent emission regulations where more than 85% of total emission is coming out before converter light-off. In addition, a recent development in catalyst material. coating technology and additive catalysts leads to a much improved OSC (Oxygen Storage Capacity) after converter light-off, current methods are very difficult to determine levels of converter aging. Therefore, it is desired to develop an OSC detecting method before converter light-off to diagnose converter failures with higher reliability. In this study, OSCs of converters are measured by an absolute measuring method and a dynamic measuring method, and some of fundamental ideas are suggested about converter OBD before converter light-off. The converters are aged with two different aging methods; those are a furnace aging and an engine bench aging: to represent aging conditions in actual field applications. Dual oxygen sensor method at the lower temperature than light-off is also studied at a model gas bench with the converters. It is fecund that there is a certain point in temperature lower than light-off where difference due to aging level becomes maximum, thus a proper dynamic method to effectively monitor catalytic converters could be implemented fur the range lower than light-off temperatures. With this result, the aging level of converters is examined at an engine bench.

• Journal of Power Electronics
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• v.18 no.4
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• pp.1007-1014
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• 2018

A novel dual DC-DC flyback converter with leakage-energy recycling is presented in this paper. Only an active switch is used for this converter. A pulse-width-modulation strategy is adopeted to control this switch. Two transformers are employed for the proposed converter. During the switch ON-period, the primary windings of the two transformers store energies. At the switch OFF-period, the energies stored in the primary windings of the two transformers are released to the output via the secondary windings of the two transformers. Meanwhile, the leakage energies of the two transformers can be recycled. The operating principles and steady-state analyses of the proposed converter are described in detail. A prototype circuit of the proposed converter is implemented for verifying the performances.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.2
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• pp.292-300
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• 2015

This paper proposes a high-efficiency, dual-mode PWM / linear buck converter with a wide-input range. The proposed converter was designed with a mode selector that can change the operation between PWM / linear mode by sensing a load current. The proposed converter operates in a linear mode during a light load and in PWM mode during a heavy load condition in order to ensure high efficiency. In addition, the mode selector uses a bit counter and a transmission gate designed to protect from a malfunction due to noise or a time-delay. Also, in conditions between $-40^{\circ}C$ and $140^{\circ}C$, the converter has variations in temperature of $0.5mV/^{\circ}C$ in the PWM mode and of $0.24mV/^{\circ}C$ in the linear mode. Also, to prevent malfunction and breakdown of the IC due to static electricity, the reliability of IC was improved by embedding a self-produced 8 kV-class(Chip level) ESD protection circuit of a P-substrate Triggered SCR type with high robustness characteristics.

• Journal of Power Electronics
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• v.17 no.3
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• pp.590-600
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• 2017

This paper presents a ripple-free input current modified interleaved boost converter for high step-up applications. By integrating dual coupled inductors and voltage multiplier techniques, the proposed converter can reach a high step-up gain without an extremely high turn-ON period. In addition, a very small auxiliary inductor employed in series to the input dc source makes the input current ripple theoretically decreased to zero, which simplifies the design of the electromagnetic interference (EMI) filter. In addition, the voltage stresses on the semiconductor devices of the proposed converter are efficiently reduced, which makes high performance MOSFETs with low voltage rated and low resistance $r_{DS}$(ON) available to reduce the cost and conduction loss. The operating principles and steady-state analyses of the proposed converter are introduced in detail. Finally, a prototype circuit rated at 400W with a 42-50V input voltage and a 400V output voltage is built and tested to verify the effectiveness of theoretical analysis. Experimental results show that an efficiency of 95.3% can be achieved.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.790-802
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• 2017

This paper proposes the modeling and control strategy to track the MPPs of hybrid PV and Wind power systems, using a new dual input boost converter. The dual input power conditioning system with an independent MPPT control scheme is introduced with minimum number of circuit elements in order to reduce the switching loss, size and cost of the system. Since the operating conditions for the PV and Wind power systems are very distinct from each other, an efficient and superior control system is required to track the MPPs of both renewable sources with the use of a simply-structured single-ended single-inductor converter. The design of Power-Conditioning System (PCS) and detail control strategy are presented in this paper. To provide independent tracking of MPPs, a variable duty-cycle control strategy is employed for the wind system and a variable frequency strategy is employed for the PV system. Finally, the proposed dual-input converter for hybrid power conditioning system is implemented and the hardware test results are presented. From the hardware experiment, it is concluded that the proposed system successfully tracks the MPPs of both of the renewable power systems independently.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.9
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• pp.1437-1443
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• 2017

Electric energy is consumed or regenerated according to an operation of electric rail cars in urban railway power substations. A thyristor dual converter system is used to deal with the electric energy. Since the AC input voltage of power substations is $22.9kV{\pm}10%$, the magnitude of the AC voltage fluctuates according to load conditions, so the secondary side voltage of the DDY transformer also fluctuates. In the thyristor dual converter, the response characteristics of the DC output voltage and the DC output current are changed based on an initial firing angle in the cross mode conversion between the forward mode and the reverse mode. Therefore, this paper proposes the initial firing angle tracking algorithm considering fluctuation of the AC input voltage. The effectiveness of the proposed algorithm is verified by a simulation compared with the conventional algorithm.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.11
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• pp.635-644
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• 2002

Many generating units can be in parallel connection to one battery and inverter. However, one of the biggest problems we encountered is that wind speed is fluctuated sharply in accordance with the unstable weather conditions. To solve this problem, we need energy storage equipment such as storage lead-acid battery. We design a system and analyze its modeling so that it supplies a stable power to the load through DC-AC inverter part. In this paper, we applied dual step-up/down buck-boost converter and dual high-frequency half-bridge converter to the proposed system. These converters are used to store energy in the battery regardless of the change of the wind speed. The operation process of two proposed types of converters for high-power battery charging is discussed along with simulation and experimental result. We design a charging circuit which is applicable in the actual wind power generation system for 30kw and confirm the circuit's validity.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.2
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• pp.150-158
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• 2017

This study proposes a new pulse-width modulation switching pattern for the low conduction loss of a three-level neutral point clamped (NPC)-based dual-active bridge (DAB) converter. The operational principle for a bidirectional power conversion is a phase-shift modulation. The conventional switching method of the three-level NPC-based DAB converter shows a symmetric switching pattern. This method has a disadvantage of high root-mean-square (RMS) value of the coupling inductor current, which leads to high conduction loss. The proposed switching method shows an asymmetrical pattern, which can reduce the RMS value of the inductor current with lower conduction loss than that of the conventional method. The performance of the proposed asymmetrical switching method is theoretically analyzed and practically verified using simulation and experiment.