• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.4
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• pp.451-462
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• 2016

Photovoltaic energy conversion becomes main focus of many researches due to its promising potential as source for future electricity and has many advantages than the other alternative energy sources like wind, solar, ocean, biomass, geothermal etc. In Photovoltaic power generation multilevel inverters play a vital role in power conversion. The three different topologies, diode-clamped (neutral-point clamped) inverter, capacitor-clamped (flying capacitor) inverter and cascaded h-bridge multilevel inverter are widely used in these multilevel inverters. Among the three topologies, cascaded h-bridge multilevel inverter is more suitable for photovoltaic applications since each pv array can act as a separate dc source for each h-bridge module. This paper presents a single phase Cascaded H-bridge five level inverter for grid-connected photovoltaic application using sinusoidal pulse width modulation technique. This inverter output voltage waveform reduces the harmonics in the generated current and the filtering effort at the input. The control strategy allows the independent control of each dc-link voltages and tracks the maximum power point of PV strings. This topology can inject to the grid sinusoidal input currents with unity power factor and achieves low harmonic distortion. A PID control algorithm is implemented in Arm Processor LPC2148. The validity of the proposed inverter is verified through simulation and is implemented in a single phase 100W prototype. The results of hardware are compared with simulation results. The proposed system offers improved performance over conventional three level inverter in terms of THD.

• Journal of Electrical Engineering and Technology
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• v.8 no.2
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• pp.304-315
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• 2013

In this paper, analysis of cascaded H-bridge multilevel inverter in DTC-SVM (Direct Torque Control-Space Vector Modulation) based induction motor drive for FCEV (Fuel Cell Electric Vehicle) is presented. Cascaded H-bridge multilevel inverter uses multiple series units of H-bridge power cells to achieve medium-voltage operation and low harmonic distortion. In FCEV, a fuel cell stack is used as the major source of electric power moreover the battery and/or ultra-capacitor is used to assist the fuel cell. These sources are suitable for utilizing in cascaded H-bridge multilevel inverter. The drive control strategy is based on DTC-SVM technique. In this scheme, first, stator voltage vector is calculated and then realized by SVM method. Contribution of multilevel inverter to the DTC-SVM scheme is led to achieve high performance motor drive. Simulations are carried out in Matlab-Simulink. Five-level and nine-level inverters are applied in 3hp FCEV induction motor drive for analysis the multilevel inverter. Each H-bridge is implemented using one fuel cell and battery. Good dynamic control and low ripple in the torque and the flux as well as distortion decrease in voltage and current profiles, demonstrate the great performance of multilevel inverter in DTC-SVM induction motor drive for vehicle application.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.1
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• pp.95-101
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• 2005

In this paper, we proposed the electric circuit using one common arm of H-Bridge Inverters to reduce the number of switching component in multi-level PWM inverter combined with H-Bridge Inverters and Transformers. and we proposed the switching method that can be same rate of usage at each transformer. Also, we tested the proposed prototype inverter to clarify the proposed electric circuit and reasonableness of control signal.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.5
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• pp.448-455
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• 2015

A model predictive control (MPC) method without individual PWM has been recently researched to simplify and improve the control flexibility of a multilevel inverter. However, the input power of each H-bridge cell and the switching frequency of switching devices are unbalanced because of the use of a restricted switching state in the MPC method. This paper proposes a control method for balancing the switching patterns and cell power supplied from each isolated dc source of a cascaded H-bridge inverter. The supplied dc power from isolated dc sources of each H-bridge cells is balanced with the proposed cell balancing method. In addition, the switching frequency of each switching device of the CHB inverter becomes equal. A simulation and experimental results are presented with nine-level and five-level three-phase CHB inverter to validate the proposed balancing method.

• Proceedings of the KIPE Conference
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• 1998.11a
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• pp.13-17
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• 1998

In recent years H-bridge multievel inverters have been focused on and selected as the power inverter in several high voltage and high power application. This paper proposes an new PWM method for the multievel H-bridge inverter systems. The proposed PWM method is a carrierwave-based space vector PWM method which utilizes the phase voltage redundancies considering both the switch and conduction loss of the devices. We describe the new PWM method in detail and the effectiveness of the new PWM method is verified by the simulation results.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.290-291
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• 2018

This paper proposed design method of DC link capasitor and leakage inductance of transformer with high voltage cascaded NPC H-bridge inverter. DC link capacitor is designed based on the ripple power between input AC power and output AC power, and leakage inductance of transformer is designed based on FFT table of unipola PWM with NPC H-bridge inverter. The proposed design method is verified by simulation results of 6.6[kV], 1.2[MW] Cascaded NPC H-bridge inverter.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.103-104
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• 2016

기존 Cascade H-bridge 인버터 토폴로지는 커패시터나 다이오드가 없이 스위치로 구성되어 있으며, 필터 없이 정현파와 유사하게 구현할 수 있다. 또한 출력전압 레벨이 높을수록 정현파와 유사하게 되어 고주파가 줄어들며, 각 셀을 직렬로 연결하면 입력전압보다 높은 출력전압 갖는다. 본 논문에서는 기존 Cascade H-bridge 인버터와 NPC(Neutral Point Clamped)가 결합한 Cascade H-bridge NPC 인버터를 제안하였다. Cascade H-bridge NPC 인버터는 기존 Cascade H-bridge 인버터 특성과 유사하며, Cascade H-bridge 인버터와 NPC 인버터의 장점을 가지고 있다. Cascade H-bridge 인버터와 Cascade H-bridge NPC 인버터를 시뮬레이션 통해 THD(Total Harmonic Distortion) 비교분석하였고 시뮬레이션은 PSIM 9.1.4을 가지고 검증하였다.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.2
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• pp.190-196
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• 2013

It presents a unification of buck-boost and flyback converter for driving a cascaded H-bridge multilevel inverter with a single independent DC voltage source. Cascaded H-bridge multilevel inverter is useful to make many output voltage levels for sinusoidal waveform by combining two or more H-bridge modules. However, each H-bridge module needs an independent DC voltage source to generate multi levels in an output voltage. This topological characteristic brings a demerit of increasing the number of independent DC voltage sources when it needs to increase the number of output voltage levels. To solve this problem, we propose a converter combining a buck-boost converter with a flyback converter. The proposed converter provides independent DC voltage sources at back-end two H-bridge modules. After analyzing theoretical operation of the circuit topology, the validity of the proposed approach is verified by computer-aided simulations using PSIM and experiments.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.2
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• pp.197-201
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• 2013

Cascaded H-bridge multilevel inverter requires independent DC voltage sources to produce multi output voltage levels. When it needs to generate more levels in the output voltage wave, the number of independent DC voltage sources usually limits its extension. To solve this problem, we propose a cascaded H-bridge multilevel inverter employing a front-end flyback converter for unifying input DC voltage sources. After theoretical analysis of the proposed circuit, we verify the validity of the proposed inverter using computer-aided simulations and experiments.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.388-390
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• 2008

본 논문에서는 새로운 H-bridge 멀티레벨 인버터 구조를 제안한다. 제안된 구조는 기존의 H-bridge 멀티레벨 인버터 구조보다 사용하는 스위칭 소자수가 적어 시스템 크기, 비용, 전력 손실, 노이즈 감소로 보다 효율적인 동작이 가능하다. 또한 레벨 수가 증가할수록 스위칭 소자는 비례적으로 감소하여 High level에서 보다 더 효율적인 동작이 가능하다. 제안된 H-bridge 멀티레벨 인버터 구조의 타당성을 검증하기 위해 PSpice 시뮬레이션을 수행하였고 제안된 구조의 우수성을 검증하였다.