Isolation transformer

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

Inductively coupled RF plasma reactor with floating coil antenna for reduced capacitive coupling

Abstract: In an inductively coupled RF plasma reactor having an inductive coil antenna connected through an RF impedance match network to an RF power source, capacitive coupling from the antenna to the plasma is reduced by isolating the coil antenna from the RF power source by an isolation transformer, so that the potential of the coil antenna is floating. The output of the RF impedance match network is connected across the primary winding of the isolation transformer while the floating coil antenna is connected across the secondary winding of the isolation transformer.

Analytical Modeling and Implementation of a Coaxially Wound Transformer With Integrated Filter Inductance for Isolated Soft-Switching DC–DC Converters

Abstract: In this paper, we propose an approach for integrating a series filter inductance in a coaxially wound transformer (CWT) as a potential alternative to conventional solenoidally wound transformers (SWT) for high-power isolated soft-switching dc–dc converters. The critical elements that determine the size and the performance of soft-switching dc–dc converters are the isolation transformer and the filter elements. While conventional SWTs using a stray magnetic field as a filter inductance often suffer from a considerably increased loss, heat congestion, and electromagnetic interference, a CWT is rarely affected by high frequency and fringing effects. The desired properties are still valid while the required filter inductance is fully integrated with an isolation transformer using the proposed method. In addition, the evenly distributed magnetic fields in a concentric geometry enable accurate electrical and mechanical analysis and a specific application-oriented design. In this paper, the operating principles, design procedure, and loss modeling of a CWT with an integrated filter inductance are introduced. Its functionality and suitability for high-frequency applications were proven by theoretical analysis and experiments. A prototype transformer with an integrated inductance 4 mH was facilitated and evaluated in a 15 kV-SiC mosfet -based 6 k–400 Vdc stage for a solid-state transformer of up to 6.5 kW at a switching frequency of 20 kHz.

PWM half-bridge converter with dual-equally adjustable control signal dead-time

Abstract: A method and system of controlling half-bridge DC—DC converters to achieve Zero Voltage Switching (ZVS) for at least one of the switches. The soft-switching half-bridge DC—DC converter system includes soft-switching for all switches by adding an additional branch with a switch and a diode across the primary side of an isolation transformer and by applying a Duty-Cycle Shifted PWM Control.

High-frequency transformer-link three-level inverter drive with common-mode voltage elimination

Abstract: This paper proposes a novel topology along with a switching strategy for AC/AC conversion with a high frequency transformer link. The input side converter is a three phase to single phase direct link matrix converter switched with a simple triangle comparison based novel PWM strategy and provides input power factor correction. This PWM technique also helps to eliminate the effect of the pulsating DC bus seen by the output inverter. The high frequency transformer provides flexible voltage transfer ratio along with galvanic isolation and has much reduced size compared to the bulky line frequency transformer. The centre tapped secondary of the transformer along with a single phase rectifier provide the required voltage levels for a three level inverter. This inverter is operated as a two level inverter in order to eliminate common mode voltages at its output. A novel variable slope carrier is used for this inverter in order to nullify the effect of fluctuating DC bus. The major advantages of this scheme are a) elimination of DC bus capacitor, b) low neutral point fluctuation, c) isolation, d) input power factor correction e) flexible voltage transfer ratio and f) high power density. The proposed configuration is simulated and simulation results are presented, which verifies the operation.

A transformerless single phase on-line UPS with 110 V/220 V input output voltage

Abstract: In this paper, it is proposed a new nonisolated UPS system configuration that allows the bypass circuit operation even if the input voltage is different from the output voltage. The UPS system is composed by an AC-DC/DC-DC three level boost rectifier/converter combined with a double half bridge inverter. This topology allows the reduction of some parameters that are commonly discussed in the nonisolated UPS systems such as size and cost, compared with others isolated UPS configurations for the same purpose. Also, the efficiency are improved due to reduced number of switches and batteries, as well as no low frequency isolation transformer is required to realize bypass operation because of the common neutral connection. Both stages of the proposed circuit operate in high frequency, using a passive nondissipative snubber circuit in the boost converter and IGBTs switches in the double half bridge inverter, with low conduction losses, low tail current and low switching losses. A simple and well-known control strategy is used. Principle of operation and experimental results for a 2.6 kVA laboratory prototype are presented to demonstrate UPS performance.