• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 추계학술대회 논문집(III)
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• pp.646-652
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• 2003

AS a main Power Supply of the Railroad Vehicles, a three-Level ZVZCS DC/DC Converter is proposed in this paper. The proposed three-Level DC/DC Converter achieves zero voltage and zero current switching for the main switches. Its attribute is that the voltage across the switches is half the value of the input voltage. Also. using a diode and secondary side of the transformer, and simple auxiliary circuits it achieves zero current switching of the auxiliary switches. The principle operation and simulation results are included.

• 전력전자학회논문지
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• 제25권1호
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• pp.44-53
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• 2020

A bridgeless single-stage AC-DC converter for wireless power charging systems is proposed. This converter is composed of a PFC stage and a three-level hybrid DC-DC stage. The proposed converter can control the wide output voltage (200-450 V_DC) by the variable link voltage and the pulse-width voltage applied to the primary resonant circuit due to the phase-shifted modulation at a fixed switching frequency. Moreover, the input power factor and the total harmonic distortion can be improved by using the proposed converter. A 1 kW prototype was fabricated and validated through experimental results and analysis.

• Journal of Power Electronics
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• 제14권3호
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• pp.499-506
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• 2014

This paper proposes a 3 kW single-phase bi-directional multi-level converter for energy storage applications. The proposed topology is based on the H-bridge structure with four switches connected to the DC-link. A simple phase opposition disposition PWM method that requires only one carrier signal is also suggested. The switching sequence to balance the capacitor voltage is considered. The topology can be extended to a nine-level converter or a three-phase system. The operating principle of the proposed converter is verified through a simulation and an experiment.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2015년도 전력전자학술대회 논문집
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• pp.357-358
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• 2015

This paper provides a comparison of power converter loss and thermal description for voltage source and current source type 5MW-class medium voltage topologies of wind turbines. Neutral-point clamped three-level converter is adopted for voltage source type topology while two-level converter is employed for current source type topology considering the popularity in the industry. In order to match the required voltage level of 4160V with the same switching device of IGCT as in voltage source converter, two active switches are connected in series for the case of current source converter. The loss analysis is confirmed through PLECS simulations. In addition, the loss factors due to di/dt and dv/dt snubber and ac input filter are presented. The comparison result shows that VSC-based wind turbine system has a higher efficiency than that of CSC under the rated operating conditions.

• 전력전자학회논문지
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• 제25권4호
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• pp.269-278
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• 2020

In this paper, two types of DC/DC converters in a hydrogen fuel cell hybrid railway vehicle system, which serve to charge high-voltage battery and supply power to an inverter for driving a driving motor, were compared and analyzed. A two-level interleaving boost converter and a three-level boost converter were compared and analyzed, and a theoretical design method was proposed to have an efficiency characteristic of over 95%. In addition, a digital controller design method considering the digital phase delay component of DSP (TMS320F28335) is presented. Finally, the validity of the theoretical design of the converter with 20kW power was verified through static and dynamic experiments respectively.

• 전력전자학회논문지
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• 제17권6호
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• pp.500-506
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• 2012

In this paper, a non-isolated high step-up and high efficiency boost converter is proposed. By using the 3-level boost converter structure, the proposed converter can obtain higher voltage gain than conventional high step-up converters. The voltage spike of the switching device is well clamped by using the clamp circuit composed of a clamp diode and a capacitor and the energy of the leakage inductor of coupled inductor is effectively transferred to output. Due to the 3-level structure, the equivalent switching frequency of the coupled inductor is doubled, which results in reduced inductor size. A 500 W prototype converter is built and tested to verify performance of the proposed converter.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.317-322
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• 2003

A novel three-level DC/DC converter (TLC)for high power applications operating from high input voltage Is proposed. Its switch voltage stress can be ensured to be only one-half of the Input voltage. Nevertheless, since all input voltage is applied to the transformer primary side, it has good turns ratio. The driving method of each module is same as those of the conventional phase-shifted ZVS full bridge PWM converter (PSFB) and the zero-voltage-switching (ZVS) of the leading leg are achieved exactly in the same manner as that of the PSFB. Moreover, its three-level operation can considerably reduce the current ripple through the output inductor and it has no problems of the DC-link voltage unbalance. Therefore, it features a low voltage stress, high efficiency, low EMI, high power density, and small sized filter. To confirm the operation, validity, and features of the proposed circuit, experimental results from a 200W, 600V/DC-48V/DC prototype are presented.

• 전력전자학회논문지
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• 제21권3호
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• pp.267-274
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• 2016

In this study, a fast charger for electric vehicle with wide charging voltage range is proposed. To achieve high efficiency, three-level topologies are employed for the AC-DC and DC-DC converters. Given that the output range of the DC-DC converter in fast chargers is quite wide, the circulating current of conventional three-level converter will increase under low voltage condition. The proposed hybrid switching method mitigates this issue. When a coupled inductor is used on the output side, the circulating current is further reduced, and the switches $S_2$, $S_3$, $S_6$, and $S_7$ achieve turning-off under the ZCS condition. Experimental results from a 50 kW prototype are provided to validate the proposed charger, and a rated efficiency of 95.9% is obtained.

• Journal of Power Electronics
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• 제18권2호
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• pp.432-444
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• 2018

This paper presents a capacitor voltage balancing topology using a three-level boost converter (TLBC) for a neutral point clamped (NPC) three-level inverter fed surface permanent magnet synchronous motor drive (SPMSM). It enhanced the performance of the drive in terms of its voltage THD and torque pulsation. The main attracting feature of the proposed control is the boosting of the input voltage and at the same time the balancing of the capacitor voltages. This control also reduces the computational complexity. For the purpose of close loop vector control, a software based cost effective resolver to digital converter RDC-less estimation is implemented to calculate the speed and position. The proposed drive is simulated in the MATLAB/SIMULINK environment and an experimental investigation using dSPACE DS1104 validates the proposed drive system at different operating condition.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.102-105
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• 2005

For transferring the primary power to the secondary one, the high frequency series resonant converter has been widely used for the contactless power supply system. However, the high frequency series resonant converter has the disadvantages such as the low efficiency, the high voltage gain characteristics and deviation of the phase angle in the overall load range. To improve this disadvantage, In this paper, the characteristics of the high efficiency and unit voltage gain as well as in phase are revealed in the proposed three-level LCLC ( Inductor - Capacitor - Inductor -Capacitor)resonant converter. The results are verified on the simulation based on the theoretical analysis and the 4kW experimental prototype.