Litz wire

About: Litz wire is a research topic. Over the lifetime, 643 publications have been published within this topic receiving 9034 citations.

Optimal choice for number of strands in a litz-wire transformer winding

Abstract: The number and diameter of strands to minimize loss in a litz-wire transformer winding is determined. With fine stranding, the AC resistance factor can be decreased, but DC resistance increases as a result of the space occupied by insulation. A power law to model insulation thickness is combined with standard analysis of proximity-effect losses to find the optimal stranding. Suboptimal choices under other constraints are also determined.

Inductive power distribution system

Abstract: A contactless inductive power distribution system operating at 10 KHz has a self tuning resonant power supply connected to a resonant primary conductive path (10110, 10111) comprising a pair of parallel litz wire conductors (10110, 10111) each encapsulated within an insulated sheath and supported on a structural monorail beam (10101) on which a plurality of electric vehicles can run. Each vehicle has an electric motor (not shown) capable of deriving power from a resonant pick-up coil (10115) wound on a ferrite core (10102) mounted on the vehicle in close proximity to the primary conductors (10110, 10111). Each vehicle also has switching means (10116) capable of preventing a lightly loaded vehicle from presenting a reduced load to the resonant primary. As shown, this comprises an isolating coil (10116) having a switch (not shown) to switch the coil between an open circuit and a short circuit, so that when the switch is switched from one state to another state the power coupled between the primary conductive path (10110, 10111) and the pick-up coil (10115) is changed.

Inductors and Transformers for Power Electronics

Abstract: FUNDAMENTALS OF MAGNETIC THEORY Basic Laws of Magnetic Theory Magnetic Materials Magnetic Circuits References FAST DESIGN APPROACH INCLUDING EDDY CURRENT LOSSES Fast Design Approach Examples Conclusions Appendix 2.A.1: Core Size Scale Law for Ferrites in Non-Saturated Thermal Limited Design Appendix 2.A.2: Eddy Current Losses for Wide Frequency Appendix 2.A.3: MathCAD Example Files References SOFT MAGNETIC MATERIALS Magnetic Core Materials Comparison and Applications of the Core Materials in Power Electronics Losses in Soft Magnetic Materials Ferrite Core Losses with Non-Sinusoidal Voltage Waveforms Wide Frequency Model of Magnetic Sheets Including Hysteresis Effects Appendix 3.A: Power and Impedance of Magnetic Sheets References COIL WINDING AND ELECTRICAL INSULATION Filling Factor Wire Length Physical Aspects of Breakdown Insulation Requirements and Standards Thermal Requirements and Standards Magnetic Component Manufacturing Sheet References EDDY CURRENTS IN CONDUCTORS Introduction Basic Approximations Losses in Rectangular Conductors Quadrature of the Circle Method for Round Conductors Losses of a Current Carrying Round Conductor in 2-D Approach Losses of a Round Conductor in a Uniform Transverse AC Field Low Frequency 2-D Approximation Method for Round Conductors Wide Frequency Method for Calculating Eddy Current Losses in Windings Losses in Foil Windings Losses in Planar Windings Appendix 5.A.1: Eddy Current 1-D Model for Rectangular Conductors Appendix 5.A.2: Low Frequency 2-D Models for Eddy Current Losses in Round Wires Appendix 5.A.3: Field Factor For Inductors References THERMAL ASPECTS Fast Thermal Design Approach (Level 0 Thermal Design) Single Thermal Resistance Design Approach (Level 1 Thermal Design) Classic Heat Transfer Mechanisms Thermal Design Utilizing a Resistance Network Contribution to Heat Transfer Theory of Magnetic Components Transient Heat Transfer Summary Appendix 6.A: Accurate Natural Convection Modeling for Magnetic Components References PARASITIC CAPACITANCES IN MAGNETIC COMPONENTS Capacitance Between Windings: Inter Capacitance Self-Capacitance of a Winding: Intra Capacitance Capacitance Between the Windings and the Magnetic Material Practical Approaches for Decreasing the Effects of Parasitic Capacitances References INDUCTOR DESIGN Air Coils and Related Shapes Inductor Shapes Typical Ferrite Inductor Shapes Fringing in Wire-Wound Inductors with Magnetic Cores Eddy Currents in Inductor Windings Foil Wound Inductors Inductor Types Depending on Application Design Examples of Different Types of Inductors Fringing Coefficients For Gapped-Wire-Wound Inductors Analitical Modeling of Combined Litz Wire-Full Wire Inductors References TRANSFORMER DESIGN Transformer Design in Power Electronics Magnetizing Inductance Leakage Inductance Using Parallel Wires and Litz Wires Interleaved Windings Superimposing Frequency Components Superimposing Modes References OPTIMAL COPPER/CORE LOSS RATIO IN MAGNETIC COMPONENTS Simplified Approach Loss Minimization in the General Case Loss Minimization Without Eddy Current Losses Loss Minimization Including Low-Frequency Eddy Current Losses Summary Examples References MEASUREMENTS Introduction Temperature Measurements Power Losses Measurements Measurement of Inductances Core Loss Measurements Measurement of Parasitic Capacitances Combined Measuring Instruments References APPENDIX A: RMS VALUES OF WAVEFORMS Definitions RMS Values of Some Basic Waveforms RMS Values of Common Waveforms APPENDIX B: MAGNETIC CORE DATA ETD Core Data (Economic Transformer Design Core) EE Core Data Planar EE Core Data ER Core Data UU Core Data Ring Core Data (Toroid Core) P Core Data (Pot Core) PQ Core Data RM Core Data APPENDIX C: COPPER WIRES DATA Round Wire Data American Wire Gauge Data Litz Wire Data APPENDIX D: MATHEMATICAL FUNCTIONS References INDEX

Printed circuit board coil

Abstract: A multilayer printed circuit board (“PCB”) coil that simulates a coil formed from litz wire. The PCB includes a plurality of alternating conductor and insulating layers interconnected to cooperatively form the coil. Each conductor layer includes a trace that follows the desired coil shape and is divided into a plurality of discrete conductor segments. The segments are electrically connected across layers to provide a plurality of current flow paths (or filaments) that undulate between the layers in a regular, repeating pattern. The coil may be configured so that each filament spends a substantially equal amount of time in proximity to the paired coil and therefore contributes substantially equally to the self or mutual inductance of the coil. Each conductor layer may include a plurality of associated traces and intralayer connector that interconnected so that each filament undulates not only upwardly/downwardly, but also inwardly/outwardly in a regular, repeating pattern.

Long range low frequency resonator and materials

Abstract: Transmission of power at low frequencies, e.g. less than 1 MHz. The power can be transmitted in various ways, using different structures included stranded wire such as Litz wire. The inductor can also use cores of ferrites for example. Passive repeaters can also be used.