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Recently an important increase of the electrical equipment in modern aircrafts is leading to an increase in the demand for electrical power. The usual electrical power distribution in aircraft applications is done via a three-phase 115Vac grid. A new trend of DC distribution is emerging employing a 270 Vdc grid. This yields the need for high-efficiency and high power-density AC-DC converters, connecting...
A strategy to improve the power factor (PF) at the point of common coupling (PCC) for microgrid applications is presented in this paper. The position of the compensating unit is selected to correct the power factor and reduce the harmonic levels of the grid current and PCC voltage in microgrid connected distributed renewable energy sources. The proposed compensation system for power factor improvement...
A distributed power balance strategy applied for DC/DC stage in Solid State Transformer (SST) is presented in this paper. Firstly, the essence of unbalanced power issue in dc/dc stage of SST is analyzed theoretically. Then an adapted droop method is developed. The proposed control strategy can not only distributed balance the dc/dc stage output power, but eliminate the voltage drop caused by the conventional...
This paper presents a compact bi-directional solidstate transformer (SST) based on a current-source topology, featuring high-frequency galvanic isolation and only two minimal power conversion stages. The topology, referenced as Dynamic Current or Dyna-C, can be configured for multiterminal DC and/or multi-phase AC applications. The Dyna-C is robust, can be stacked for MV applications, and be paralleled...
Two AC-DC converter topologies for 3-phase utility grid interface using high frequency (HF) or medium frequency (MF) transformers have been proposed in this paper. The transformer primary side converter structure is similar in both the topologies (say T-I and T-II), but the secondary side converter structures as well as the modulation schemes are different. The line-frequency AC voltage from the utility...
This paper presents an experimental verification of the Improved Switched Inductor Z-Source Inverter (ISL-ZSI). The ISL-ZSI has been proposed to overcome the limitations of classical Z-Source Inverter (ZSI) such as lower voltage gain, higher capacitor voltage stress of Z-network and huge inrush current that appears in the case of traditional ZSI. In this paper, different aspects will be presented...
This paper presents a new grid-connected delta inverter system (DIS) for large scale photovoltaic (PV) power systems. The delta inverter achieves DC to three phase AC inversion by using only three power semiconductor devices instead of six devices as in a conventional full bridge three phase inverter. This reduction in the number of switching devices contributes to higher power density for PV energy...
In existing half/full-bridge high precision amplifiers output distortion is present due to the required switch blanking time. The OCC topology does not require this blanking time but has a much higher total inductor volume compared to the half-bridge. In this paper a patented new topology is introduced that has the advantages of the OCC but with a much lower total inductor volume. The basic operation...
A quasi resonant topology suitable for LED drivers, featuring power factor correction and dimming in a single stage is presented. It contains a single active switch, and operates in zero-voltage-switching, zero-current-switching. This topology includes neither electrolytic capacitors nor transformer, and provides galvanic isolation between the AC mains and the DC side. Building on this new topology,...
For a conventional offline Buck-Boost LED driver, significant low frequency ripple current is produced when a high power factor has been achieved. In this paper, an innovative LED driver technology based on the Buck-Boost topology has been proposed. The featured configuration has greatly reduced the low frequency ripple current without compromising power factor performance. High efficiency and low...
An interleaved bidirectional switched capacitor converter with regulation capability is proposed in this paper. This converter is able to step up the voltage to near three times and regulate the output, while maintaining continuous input current as well as small output voltage ripple. Due to its natural interleaved structure, fewer components are required compared with traditional interleaved switched-capacitor...
Flyback converters are widely used in several applications, however, with this topology it is very challenging to achieve high voltage operation especially with very high step-up ratio (>500) within limited space. This paper presents a new flyback-based topology which utilizes primary parallel and secondary series transformer connection in order to achieve very high step-up ratio (up to 650) as...
Natural capacitor voltage balancing for Flying Capacitor and Stacked Multicell converters require uniform distribution of switching transitions among cells. The state-machine-decoder has been known as the optimal technique to achieve this goal. In this paper, however, it is shown that the conventional state-machine-decoder may not generate the optimal balancing scheme for Stacked Multicell converters...
In many rural areas, due to unavailability of three-phase AC power, three-phase Variable Frequency Drives (VFDs) are often required to operate from single-phase AC source. Powering up three-phase VFDs from single-phase AC source requires addressing many issues — higher rms value of input diode current, higher ripple voltage across the DC bus capacitor, higher peak input current, higher input current...
The developmental process and the battery charging strategy of 100W battery charging circuits using a three-phase permanent magnet synchronous generator are presented. It is assumed that a typical male can comfortably generate over 100W using cranking motions with two feet. Using a portable and manual generator, human cranking motions are converted to three-phase ac electric power, and the electric...
In this paper, a new hybrid resonant bridgeless ac-dc PFC boost converter operating in continuous-conduction-mode (CCM) is proposed for neighborhood electric vehicle (NEV) battery charging. This hybrid-resonant boost converter has two active switches that operate in pulse-width modulation (PWM) and hybrid-resonant modes of operation. This combined modulation technique is called hybrid resonant PWM...
This paper presents the feasibility study of bipolar pads for extremely high efficiency wireless battery chargers used in electric vehicle (EV) and plug-in hybrid electric vehicle (PHEV) applications. Due to the unconventional flux distribution in this system, a 3D finite element method was employed for its design and analysis. The importance of misalignment tolerance in this system is analyzed and...
In this paper, a plug-in electric vehicle battery charger is proposed based on SEPIC PFC and LLC topologies. In addition, a new approach in introduced to actively control the dc link voltage and track the maximum efficiency point of a LLC converter over the wide voltage range of the high voltage battery pack. Comprehensive circuit modeling and loss analysis at maximum efficiency point of LLC converter...
Presently, multi-string topology is considered the state of the art for grid integration of high power photovoltaic (PV) systems. In this paper, an improvement of the basic multi-string topology is presented which uses a three-level neutral point clamped (3L-NPC) converter as central grid tied inverter. Each of the two capacitors of the split dc link in 3L-NPC converter is fed from a separate multi-string...
To improve the efficiency of the photovoltaic (PV) system, the centralized topology using three-level inverters are widely used. In this system, PV modules are separately connected to the split DC-links. This causes a decrease of maximum power point tracking (MPPT) efficiency under the partial shading condition. This paper proposes an independent control of two DC-link voltages for separate MPPT of...
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