Isolation transformer

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

Gapped Transformer Design Methodology and Implementation for LLC Resonant Converters

Abstract: In the LLC resonant converter, the air gap is generally positioned in the core of the transformer for proper magnetizing inductance. Traditional transformer design methods assume infinite permeability of the core and no energy stored in the core. The improved design methodology for the gapped transformer is proposed with the optimum relative permeability and gap selection to meet the temperature rise and the magnetizing inductance requirements. The magnetizing current influences the magnetic flux in the core leading to the core saturation and core loss, while the resonant current contributes to the winding loss. The transformer design for a 200 W, 90 kHz LLC resonant converter is presented and experimental results validate the proposed methodology.

High frequency power transformer modeling for Power Line Communication applications

Abstract: This paper deals with the modeling of distribution power transformer with the frequency up to 10 MHz for power line communication (PLC) applications. For this purpose, a new approach to model the transformer is proposed. Then, the elaboration of the model from the impedance measurement in frequency domain is presented. For the determination of the parameters of model, the necessary methods are introduced. The simulation is carried out with ATP/EMTP to compare the characteristic of the measured impedance and the model. In order to verify the model, the small signal transfer through the transformer is measured and compared with the simulation

Preventing transformer saturation in bi-directional dual active bridge buck-boost DC/DC converters

Abstract: In switch-mode power electronic converters, DC offset of the magnetizing flux in the isolation transformer can cause saturation. In typical single-ended dc/dc converters, this is handled using a current loop which ensures that the average current in the winding is zero. For bi-directional dc/dc converters with active bridges on both sides, there exists a danger of impressing dc offsets from both sides, creating significant issues in terms of preventing transformer saturation. This paper demonstrates the issue for the Dual Active Bridge Buck Boost converter (DAB3). The paper also presents a control strategy for avoiding such saturation, eliminating DC currents on both sides, while realizing full converter control. The paper presents simulation results to prove the proposed control technique.

Transformer system for power line communications

Abstract: A transformer system couples a control panel with a power line to support two-way communications over the power line. A first transformer steps-down the power line voltage, supplying power to the control panel. A second transformer and associated capacitors provide a low impedance path at the communication signal frequencies and a high impedance path at the power frequency.

Overvoltages in power transformers caused by no-load switching

Abstract: When an unloaded power transformer is switched on via a relatively long cable, sometimes extreme high voltages appear at the secondary side of the transformer. These overvoltages are caused by a resonant phenomenon that occurs when the resonant frequencies of the transformer and the cable match. The resonant frequency of the cable feeder is equal to the reciprocal of 4 times its travel time /spl tau/. The resonant frequency of the transformer is determined by its short-circuit inductance and the capacitance which is connected to the secondary winding. In this paper a model of this phenomenon is presented and an example of this resonant phenomenon, leading to the insulation breakdown at the secondary side of a power transformer, is given. >