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RISS 인기검색어
- 검색키워드
- 저자 : H-P. Nee (검색결과 4 건)
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Dual control used in series-loaded resonant converter with SiC devices
G. Tolstoy,P. Ranstad,J. Colmenares,F. Giezendanner,H-P. Nee 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
This paper presents the performance of silicon carbide (SiC) switches in a series-loaded resonant (SLR) converter with dual control (DuC). It is shown that the SiC metal oxide-semiconductor field-effect transistor (MOSFET) with DuC increases the overall efficiency of the SLR converter compared to frequency modulation (FM). For the SiC bipolar junction transistors (BJT), the loss reduction with DuC instead of FM is not as dramatic as for the MOSFET case. Regardless of which transistor type used, the switching losses are around 20 % of the total losses at around 25 kHz. With DuC an almost constant switching frequency is used over the full voltage range compared to FM were the switching frequency increases by 13 %. Additionally a reduction of capacitive snubbers is achieved with DuC.
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High-Efficiency Step-down Converter for On-board Thermoelectric Generators on Heavy Duty Vehicles
A. Risseh,H-P. Nee 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
Today’s combustion engines have low efficiency and a large amount of useful energy converts to heat as waste in different type of vehicles. Improving the dynamics of the car body, injection system, the shape of the internal engine components and manipulating the fuel compositions have had influence on fuel economy, but still less than 50% of energy in the fuel is converted to useful mechanical power. Since the lost energy escapes through the exhaust system as heat, taking advantage of thermoelectricity, part of that energy can be converted to useful electrical energy, improving the overall efficiency. However, the output voltage from a thermoelectric generator is a function of hot and cold side temperature and since, the electrical system of the vehicle operates with constant voltage, the use of a power converter is necessary. In this paper, simulation and experimental results of such a high-efficiency converter(94-96%), designed for thermoelectric generators on heavy duty vehicles is presented and discussed.
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K. Ilves,A. Antonopoulos,S. Norrga,H-P. Nee 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
This paper presents a new modulation method for the modular multilevel converter. The proposed method is based on a fixed pulse pattern where harmonic elimination methods can be applied. Modulation methods with harmonic elimination based on calculated pulse patterns have been presented for other multilevel topologies. However, similar modulation schemes have not yet been presented for the modular multilevel topology. In the proposed modulation method, the pulse pattern is chosen in such a way that the stored energy in each submodule remains stable. It is shown that this can be done at the fundamental switching frequency without measuring the capacitor voltages or using any other form of feedback control. Such a modulation scheme has not been presented before. The theoretical results are verified by both simulations and experimental results. The simulation results show successful operation at the fundamental switching frequency with a larger number of submodules. When a smaller number of submodules are used, harmonic elimination methods may be applied. This is verified experimentally on a converter with eight submodules per phase leg. The experimental results verify that stable operation can be maintained at the fundamental switching frequency while successfully eliminating the fifth harmonic in the ac-side voltage.
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Semi-Full-Bridge Submodule for Modular Multilevel Converters
K. Ilves,L. Bessegato,L. Harnefors,S. Norrga,H.-P. Nee 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
The energy variations in each arm of the modular multilevel converter comprises two components. The first component relates to the difference between the instantaneous input and output power of each phase-leg, and the second component relates to the energy which is moved back and forth between the two arms of the phase-leg. The latter component can be reduced or even eliminated if the peak-to-peak amplitude of the alternating voltage is greater than the pole-to-pole voltage of the dc link. This will, however, require submodules which can insert negative voltages. Therefore, a semi-full-bridge submodule which uses less semiconductors than the conventional fullbridge is proposed. Simulation results shows that by using the negative voltage-levels the capacitor voltage ripple can be reduced by up to 59%. Experimental results also shows that a 7-level voltage waveform can be generated using only one semi-full-bridge submodule with two capacitors per arm.
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