• Journal of Power Electronics
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• v.15 no.1
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• pp.116-122
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• 2015

This paper presents a new current sharing control strategy for parallel-connected, synchronised three-phase DC-AC converters employing space vector pulse width modulation (SVPWM) without current sharing reactors. Unlike conventional control methods, the proposed method breaks the paths of the circulating current by dividing the switching cycle evenly between parallel connected equally rated converters. Accordingly, any inter-module reactors or circulating current control will be redundant, leading to reductions in system costs, size, and control algorithm complexity. Each converter in the new scheme employs a synchronous dq current regulator that uses only local information to attain a desired converter current. A stability analysis of the current controller is included together with a simulation of the converter and load current waveforms. Experimental results from a 2.5kVA test rig are included to verify the proposed control method.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.5
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• pp.455-461
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• 2015

This paper deals with an experimental verification of a temperature-dependent power loss model of a DC/DC converter in severe temperature conditions. The power loss of a DC/DC converter is obtained by summing the losses by the components constituting the converter including switching elements, diodes, inductors, and capacitors. MIL-STD-810F stipulates that any electronic devices must be operable in the temperature ranging from $-50^{\circ}C$ to $70^{\circ}C$. We summarized the temperature-dependent loss models for the converter components. A SEPIC-type converter is designed and built as a target. Using a constant-temperature chamber, a test rig is set up to measure the power loss of the converter. The experimental results confirm the validity of the loss model within 4.5% error. The model can be useful to predict the efficiency of the converter at the operating temperature, and to provide guidelines in order to improve the efficiency.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2562-2564
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• 1999

We have development the electronic ballast for metal halide discharge (MHD) lamp. The ballast consists of the boost pre-converter for power factor correction (PFC), a flyback a converter, half-bridge inverter and ignitor. To reject acoustic resonance phenomena, we have designed electronic ballast driving with the low frequency square wave. As results of this study, the ballast had not flicker phenomena and promoted corrected the factor (PF) highly

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.346-349
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• 2004

The design of DC-DC converters for power electronic interfaces in power management systems for Hybrid Electric Vehicle (HEV) is a very challenging task. In this paper, the considered topology is the hi-directional buck-boost converter and inverter system. If we make the converter side DC link current the same as the inverter side DC link current in a converter-inverter system, no current will flow through the BC link capacitor and as a result, no DC link voltage variation occurs. This leads to the possibility of reducing small th size of DC link capacitors which are expensive, bulky. Therefore we propose the converter current controller which can manage to match inverter and converter current at the DC link.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.3
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• pp.298-304
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• 2014

In this paper, a novel topology for cascade multilevel converter is introduced, which has many levels with fewer number of power electronic components. Less number of the switches leads to the reduction of size, losses, simple control strategy and high efficiency. For proposed multilevel converter, a new algorithm for determination of dc voltage source values has been recommended. The performance and operation of the proposed multilevel converter has been evaluated with the simulation results of a cascade 25-level converter.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.1
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• pp.1-9
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• 2003

In this paper, prototype of high-power-factor single-stage electronic ballast for fluorescent lamp is designed and implemented. A new low cost single stage high power factor electronic ballast for fluorescent lamps is based on integration of two-boost converter and LC type high frequency resonant inverter. The proposed ballast is combined by simple construction, because full bridge rectifier diode is eliminated and simple control circuit is applied. Boost converter operate in the voltage of positive and negative half cycle respectively at line frequency (60㎐), operation in discontinuous conduction mode performs high power factor. The experimental results show the good performance as PF 0.99, THD 15.4%, and CF 1.65 at output 63.5〔W〕.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.2B no.3
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• pp.133-139
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• 2002

In this paper, a prototype of an active auxiliary quasi-resonant DC link (QRDCL) snubber assisted voltage source bidirectional power converter (AC to DC and DC to AC) operating at zero voltage soft-switching (BVS) PWM nlode is presented for a Battery Energy Storage System (BESS). The operating principle of this QRDCL circuit and multifunctional control-based converter system, including PWM inverter mode in which energy flows from the battery bank to the three-phase utility-grid in addition to an active PWM converter mode in which energy flows from the utility-grid to the battery banks are described respectively by the control implementation on the basis of d-q coordinate plane transformation. The multifunctional operation characteristics of this three-phase ZVS PWM bi-directional converter with QRDCL is demonstrated fer a BESS under the power conditioning and processing schemes of energy supply mode and energy storage mode, and compared with a conventional three-phase hard switching PWM bi-directional converter for a BESS. The effectiveness of the three-phase ZVS PWM hi-directional converter with QRDCL is proven via the simulation analysis.

• Transactions on Electrical and Electronic Materials
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• v.18 no.2
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• pp.103-110
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• 2017

The number of applications of solar photovoltaic (PV) systems in power generation grids has increased in the last decade because of their ability to generate efficient and reliable power in a variety of low installation in domestic applications. Various PV converter topologies have therefore emerged, among which the modular multilevel converter (MMC) is very attractive due to its modularity and transformerless features. The modeling and control of the MMC has become an interesting issue due to the extremely large expansion of PV power plants at the residential scale and due to the power quality requirement of this application. This paper proposes a novel control method of MMC which is used to directly integrate the photovoltaic arrays with the power grid. Traditionally, a closed loop control has been used, although circulating current control and capacitors voltage balancing in each individual leg have remained unsolved problem. In this paper, the integration of model predictive control (MPC) and traditional closed loop control is proposed to control the MMC structure in a PV grid tied mode. Simulation results demonstrate the efficiency and effectiveness of the proposed control model.

• Journal of Power Electronics
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• v.18 no.2
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• pp.343-355
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• 2018

A wide-voltage-conversion range bidirectional DC-DC converter is proposed in this paper. The topology is comprised of one typical LC energy storage component and a special common grounded asymmetric H-bridge with four active power switches/anti-parallel diodes. The narrow output PWM voltage is generated from the voltage difference between two normal (wider) output PWM voltages from the asymmetric H-bridge with duty cycles close to 0.5. The equivalent switching frequency of the output PWM voltage is double the actual switching frequency, and a wide step-down/step-up ratio range is achieved. A 300W prototype has been constructed to validate the feasibility and effectiveness of the proposed bidirectional converter between the variable low voltage side (24V~48V) and the constant high voltage side (200V). The slave active power switches allow ZVS turn-on and turn-off without requiring any extra hardware. The maximum conversion efficiency is 94.7% in the step-down mode and 93.5% in the step-up mode. Therefore, the proposed bidirectional topology with a common ground is suitable for energy storage systems such as renewable power generation systems and electric vehicles with a hybrid energy source.

• Journal of Power Electronics
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• v.14 no.3
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• pp.507-518
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• 2014

This paper presents a new cascaded asymmetrical single phase multilevel converter with a lower number of power semiconductor switches and isolated DC sources. Therefore, the number of power electronic devices, converter losses, size, and cost are reduced. The proposed multilevel converter topology consists of two H-bridges connected in cascaded configuration. One H-bridge operates at a high frequency (high frequency inverter) and is capable of developing a two level output while the other H-bridge operates at the fundamental frequency (low frequency inverter) and is capable of developing a multilevel output. The addition of each power electronic switch to the low frequency inverter increases the number of levels by four. This paper also introduces a hybrid switching algorithm which uses very simple arithmetic and logical operations. The simplified hybrid switching algorithm is generalized for any number of levels. The proposed simplified switching algorithm is developed using a TMS320F2812 DSP board. The operation and performance of the proposed multilevel converter are verified by simulations using MATLAB/SIMULINK and experimental results.