Isolation transformer

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

Piezoelectric transformer driving circuit

Abstract: A piezoelectric transformer driving circuit includes a boosting circuit receiving an input DC voltage to generate an AC voltage for driving a piezoelectric transformer, a frequency control circuit for controlling the frequency of the AC voltage applied to the piezoelectric transformer to control a step-up ratio of the piezoelectric transformer, and a drive voltage control circuit for controlling the voltage of the AC voltage applied to the piezoelectric transformer at a predetermined level, regardless of variation of the input DC voltage.

Gyrator-capacitor modeling: a better way of understanding magnetic components

Abstract: Engineers new to power electronics often find magnetic components puzzling, especially multi-winding devices and integrated magnetics. Gyrator-capacitor modeling offers an alternative way of understanding such components. This tutorial paper begins with a review of the gyrator-capacitor approach, followed by some examples drawn from the field of DC-DC power conversion: a simple choke; a flyback-converter transformer; a pair of coupled chokes (in which the zero-ripple phenomenon is explained); and a two-output forward-converter transformer. Finally, core saturation is modeled by means of nonlinear capacitance and illustrated by SPICE simulation. Gyrator-capacitor modeling offers a unified, logical way of understanding the magnetic components commonly met with in power electronics. >

Apparatus for Online Power Transformer Winding Monitoring Using Bushing Tap Injection

Abstract: Online transformer condition monitoring techniques based on transfer function methods, such as transmission-line diagnostics and swept frequency-response analysis, require the injection of a known test signal into the transformer On larger power transformers, a practical method is to use the available bushing tap connection In this paper, we will discuss a custom high-power signal generator that injects high-frequency signals on the bushing tap of the transformer under investigation, as well as a circuit to replace the bushing tap short and allow online operation of the system Finally, the system is demonstrated on a 650 kV transformer

RF antenna coupling structure

Abstract: An RF antenna coupling structure includes a first transformer, a second transformer, and a transformer balun. The first transformer includes a primary winding and a secondary winding, wherein the primary winding of the first transformer is operably coupled to a power amplifier, and wherein the secondary winding of the first transformer has a desired output impedance corresponding to the operational needs of the power amplifier. The second transformer includes a primary winding and a secondary winding, wherein the primary winding of the second transformer is operably coupled to a low noise amplifier, and wherein the secondary winding of the second transformer has a desired output impedance corresponding to the needs of the low noise amplifier. The transformer balun includes a differential winding and a single-ended winding, wherein the differential winding is operably coupled to the secondary windings of the first and second transformers and the single-ended winding is operably coupled to an antenna.

Three-Phase LLC Series Resonant DC/DC Converter Using SiC MOSFETs to Realize High-Voltage and High-Frequency Operation

Abstract: SiC MOSFETs are applied to constitute a three-phase, 5-kW LLC series resonant dc/dc converter with isolation transformers. A switching frequency of around 200 kHz for the transistors successfully reduces the volume of these isolation transformers, whereas insulated-gate bipolar transistors (IGBTs) are not capable of achieving such a high switching speed. The high-voltage tolerance of SiC MOSFETs, 1200 V, enables increasing the input voltage up to 600 V. High-voltage tolerance, on the other hand, is not compatible with low on-resistance for Si MOSFETs. A three-phase circuit topology is used to achieve up to 5 kW of power capacity for the converter and reduce per-phase current at the same time. Current-balancing transformers among these three phases effectively suppress a maximum peak current from arising in the circuit, a technique that miniaturizes the input and output capacitances. The conversion efficiency of the converter reaches 97.6% at 5-kW operation.