New Considerations in the Input Filter Design of a Three-Phase Buck-Type PWM Rectifier for Aircraft Applications

An EMI filter for a three-phase buck-type medium power pulse-width modulation rectifier is designed. This filter considers differential mode noise and complies with MIL-STD-461E for the frequency range of 10kHz to 10MHz. In industrial applications, the frequency range of the standard starts at 150kHz and the designer typically uses a switching frequency of 28kHz because the fifth harmonic is out of the range. This approach is not valid for aircraft applications. In order to design the switching frequency in aircraft applications, the power losses in the semiconductors and the weight of the reactive components should be considered. The proposed design is based on a harmonic analysis of the rectifier input current and an analytical study of the input filter. The classical industrial design does not consider the inductive effect in the filter design because the grid frequency is 50/60Hz. However, in the aircraft applications, the grid frequency is 400Hz and the inductance cannot be neglected. The proposed design considers the inductance and the capacitance effect of the filter in order to obtain unitary power factor at full power. In the optimization process, several filters are designed for different switching frequencies of the converter. In addition, designs from single to five stages are considered. The power losses of the converter plus the EMI filter are estimated at these switching frequencies. Considering overall losses and minimal filter volume, the optimal switching frequency is selected.

Edge Detection by Adaptive Splitting II. The Three-Dimensional Case

In Llanas and Lantarón, J. Sci. Comput. 46, 485–518 (2011) we proposed an algorithm (EDAS-d) to approximate the jump discontinuity set of functions defined on subsets of ℝ d . This procedure is based on adaptive splitting of the domain of the function guided by the value of an average integral. The above study was limited to the 1D and 2D versions of the algorithm. In this paper we address the three-dimensional problem. We prove an integral inequality (in the case d=3) which constitutes the basis of EDAS-3. We have performed detailed computational experiments demonstrating effective edge detection in 3D function models with different interface topologies. EDAS-1 and EDAS-2 appealing properties are extensible to the 3D case

Optimizing three-phase planar transformer construction

A three-phase transformer with flat conductor layers is proposed in this article. This arrangement is used for high current density transformers. Cost effectiveness in planar magnetic are related with the optimization in the number of layers in each winding. This fact takes more relevance for the medium and high power three-phase transformers where the number of parallels to achieve the required DCR is increased. The proposed method allows the use of off-the-shell core shapes that are used for single phase transformers. Cost impact is significant and design implications become more flexible. The proposed solution has been validated and compared using the conventional and the proposed methodologies to design a high power (20 kW) transformer.

Analysis and optimized design of a distributed multi-stage EMC filter for an interleaved three-phase PWM-rectifier system for aircraft applications

Different possible input filter configurations for a modular three-phase PWM rectifier system consisting of three interleaved converter cells are studied. The system is designed for an aircraft application where MIL-STD-461E conducted EMI standards have to be met and system weight is a critical design issue. The importance of a LISN model on the simulated noise levels and the effect of interleaving and power unbalance between the different converter modules is discussed. The effect of the number of filter stages and the degree of distribution of the filter stages among the individual converter modules on the weight and losses of the input filter is studied and optimal filter structures are proposed.

An alternative for reducing the layers in the construction of three-phase planar transformers

A modified winding layout for three-phase transformers with PCB windings is proposed in this paper. This modified layout can be used in high current transformers with many PCB layers to simplify the fabrication process. One of the key factors that might increase the cost and complexity in the construction of planar transformers is the number of layers of each PCB winding. This issue becomes even more important in medium-high power three-phase transformers, where the number of PCB layers is higher. In addition to that, the proposed method allows the use of commercial core shapes that are commonly used to design single-phase transformers. This fact makes possible the reduction of cost and flexibility of the design solutions. The proposed solution has been validated and compared using the conventional and the proposed methodologies to design a high power (20 kW) transformer.

Adaptive Control for ZVS Three Phase Full Active Bridge Converter with ARCN

This paper presents an adaptive control for the auxiliary circuit, called ARCN (Auxiliary Resonant Commutating Network), used to achieve ZVS in full active bridge converters under a wide load range. Depending on the load conditions, the proposed control adapts the timing of the ARCN to minimize the losses. The principle of operation and implementation considerations are presented for a three phase full active bridge converter, proposing different methods to implement the control according to the specifications. The experimental results shown verify the proposed methodology.

Interleaved multi-cell isolated three-phase PWM rectifier system for aircraft applications

Recently there has been an important increase in electric equipment, as well as, electric power demand in aircrafts applications. This prompts to the necessity of efficient, reliable, and low-weight converters, especially rectifiers from 115VAC to 270VDC because these voltages are used in power distribution. In order to obtain a high efficiency, in aircraft application where the derating in semiconductors is high, normally several semiconductors are used in parallel to decrease the conduction losses. However, this is in conflict with high reliability. To match both goals of high efficiency and reliability, this work proposes an interleaved multi-cell rectifier system, employing several converter cells in parallel instead of parallel-connected semiconductors. In this work a 10kW multi-cell isolated rectifier system has been designed where each cell is composed of a buck type rectifier and a full bridge DC-DC converter. The implemented system exhibits 91% of efficiency, high power density (10kW/10kg), low THD (2.5%), and n−1 fault tolerance which complies, with military aircraft standards.

The Role of Education and Government in Shaping Muslim Women's Rights: Three Contemporary Case Studies

The rise in Muslim terrorist activities has encouraged the West to reevaluate its understanding of Islam, prompting concern for Muslim women's rights. In search of education-based solutions, this project explores three case studies of Muslims living under different government types: a secular state with a primarily Muslim population (Turkey); a secular state with a significant Muslim minority population (France); and a Muslim state with a powerful religious influence (Afghanistan). The type of government plays a significant role in Muslim women's rights, and solutions must be based on individual aspects of each unique place where Muslims live today. The results show that education is a universal solution when accepted at all levels: governmental, communal, and the individual.

A report on the three-dee, three-phase 20-inch cyclotron /

Unclassified Physics Distribution.

Three phase system for statewide evaluation of occupational education programs : team leader handbook.

Cover title.

Organizational maintenance repair parts and special tools list : air conditioning units, electric motor driven, 9,000 Btu/hr, vertical compact, 115 volt, single phase, 50/60 cycle (Therm-Air Manufacturing Co. model CV-9-1-15-60) FSN 4120-935-1609; 9,000 Btu/hr, vertical compact, 230 volt, three phase, 50/60 cycle ....

"February 1970."

Operator, organizational, direct support, general support and depot maintenance manual : air conditioning units, electric motor driven, 6,000 BTU/hr, vertical compact, 115 volt, single phase, 50/60 cycle (Thermo-Air model CV-6-1-15-60), FSN 4120-935-1608, 6,000 BTU/hr vertical compact, 208 volt, three phase, 400 cycle (Thermo-Air model CV-6-3-08-400), FSN 4120-935-1607.

Includes index.

Operator, organizational, direct support, general support, and depot maintenance manual : air conditioner, vertical, compact, 208 volts, A.C., 400 hertz, three phase, 18,000 BTU/hr cooling, 12,000 BTU/hr heating, (Keco model F18T4-2) FSN 4120-168-1775.

Includes index.

Operator's, organizational, direct support, and general support maintenance manual : air conditioner, horizontal, compact, 9,000 BTU/hr, 208 volt, three phase 50/60 hertz, model ECU-9HC326, NSN 4120-01-193-4998.

"27 March 1987."