Isolation transformer

About: Isolation transformer is a research topic. Over the lifetime, 8145 publications have been published within this topic receiving 72396 citations.

An actively cooled 120 kW coaxial winding transformer for fast charging electric vehicles

Abstract: A 120 kW coaxial winding transformer has been built and tested to verify previous indications that a high power transformer is feasible with the key attributes of this novel design, namely: low leakage inductance, minimal effect of leakage field on core losses, low copper losses, and a convenient "nesting" structure well suited for separability of the findings. The power transfer capability is more than double that of any previously published result for coaxial winding transformers. The application chosen for the fabricated transformer was an inductive coupler for fast charging of electric vehicles. Presented are the key parametric decisions, their impact on transformer fabrication and characteristics, and the results of these design choices as observed in the experimental data. The final design has active cooling to facilitate high power density and a separable core to allow the primary and secondary windings to be coupled and uncoupled. The experimental data shows performance better than expected, with a magnetizing to leakage inductance ratio of 1000:1, efficiency well over 99% and power density of 25 kW/kg.

An Airborne Radar Power Supply With Contactless Transfer of Energy—Part II: Converter Design

Abstract: A magnetic link is established between the stationary and revolving frames of a radar system by means of a rotating transformer. Based on the magnetics analysis of Part I of the series, a design methodology is proposed for integrating a rotating transformer into a power electronic converter using the efficiency and voltage gain plots. It is shown that a phase-shifted full-bridge topology can effectively utilize the parasitic components of the transformer. The increased magnetizing current assists the resonant transition, and this, in turn, compensates for the increased conduction losses that a rotating transformer yields. The proposed design method secures the soft-switching operation of the converter over the entire load range and allows efficient operation and reduced electromagnetic emissions. The methodology is evaluated experimentally, and the resulting prototype demonstrates an average efficiency of 92.6% in the 0.2-1-kW output power range. The proposed topology extends the power capacity of the rotating transformer without compromising its size, cost, or performance. A comparison between the slip rings and rotating transformer solutions highlights the merits and weaknesses of each technology.

Passive network tap device

Abstract: A tap device comprises a network entry connection, a network exit connection, and a network interconnection path there between. A high impedance tap circuit is electrically connected to the network connection path, and comprises an isolation transformer and active buffer element. Advantageously, a power interruption to said tap circuit does not affect network communications.

Load condition controlled power strip

Abstract: In accordance with various aspects of the present invention, a method and circuit for reducing power consumption of a power strip is provided. In an exemplary embodiment, a power strip is configured for reducing or eliminating power during idle mode by disengaging an outlet from power input. A power strip may include two or more outlets and two or more outlet circuits, with AC power input connected to the outlets through the outlet circuit(s), which may include a current transformer, a control circuit, and a switch. The current transformer secondary winding provides an output power level signal proportional to the outlet load. If behavior of the current transformer secondary winding indicates that the outlet is drawing substantially no power from the AC power input, the switch facilitates disengaging of the current transformer primary from the outlet.

High frequency matrix transformer

Abstract: A high frequency matrix transformer comprises a plurality of interdependent magnetic elements (101) arranged and interwired to provide very low leakage inductance and very good coupling from the primary (102) to the secondary (103). The matrix transformer is particularly well adapted for high equivalent turns ratios, high frequency, high power, and high dielectric isolation. It can have parallel secondaries (103) which can source current to parallel rectifier circuits (CR1, CR2) with current sharing. It can also have parallel primary circuits (102) to balance the load between source switching circuits (Q1, Q2) to provide dual input voltage capability. The matrix transformer can be very flat, making it easy to ventilate or heat sink. The matrix transformer having push pull windings can include the primary switching means (Q1, Q2) and secondary rectifying means (CR1, CR2) within its windings, so that the transformer as a whole has direct current inputs and outputs.