Isolation transformer

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

A Proportional ${\bm +}$ Multiresonant Controller for Three-Phase Four-Wire High-Frequency Link Inverter

Abstract: A new solution for unbalanced and nonlinear loads in terms of power circuit topology and controller structure is proposed in this paper. A three-phase four-wire high-frequency ac-link inverter is adopted to cater to such loads. Use of high-frequency transformer results in compact and light-weight systems. The fourth wire is taken out from the midpoint of the isolation transformer in order to avoid the necessity of an extra leg. This makes the converter suitable for unbalanced loads and eliminates the requirements of bulky capacitor in half-bridge inverter. The closed-loop control is carried out in stationary reference frame using proportional + multiresonant controller (three separate resonant controller for fundamental, fifth and seventh harmonic components). The limitations on improving steady-state response of harmonic resonance controllers is investigated and mitigated using a lead-lag compensator. The proposed voltage controller is used along with an inner current loop to ensure excellent performance of the power converter. Simulation studies and experimental results with 1 kVA prototype under nonlinear and unbalanced loading conditions validate the proposed scheme.

Design Considerations and Development of an Innovative Gate Driver for Medium-Voltage Power Devices With High $dv/dt$

Abstract: Medium-voltage (MV) silicon carbide (SiC) devices have opened up new areas of applications which were previously dominated by silicon-based IGBTs From the perspective of a power converter design, the development of MV SiC devices eliminates the need for series connected architectures, control of multilevel converter topologies which are necessary for MV applications, and the inherent reliability issues associated with it However, when SiC devices are used in these applications, they are exposed to a high peak stress (5–10 kV) and a very high $dv/dt$ (10–100 kV/ $\mu$ s) Using these devices calls for a gate driver with a dc–dc isolation stage that has ultralow coupling capacitance in addition to be able to withstand the high isolation voltage This paper presents a new MV gate driver design to address these issues while maintaining a minimal footprint for the gate driver An MV isolation transformer is designed with a low interwinding capacitance, while maintaining the clearance, creepage, as well as insulation standards A dc isolation test has been performed to validate the integrity of the insulating material The key features include low input common mode current, and a short-circuit protection scheme specifically designed for 10 kV SiC mosfet s The performance of the gate driver is evaluated using double pulse tests and continuous tests Experimental results validate the advantages of the gate driver and its application for MV SiC devices exhibiting very high $dv/dt$ The proposed gate driver concept is aimed at providing an efficient and reliable method to drive MV SiC devices

Power Electronic Traction Transformer: Efficiency Improvements Under Light-Load Conditions

Abstract: Power electronic transformer (PET), a converter technology that utilizes power semiconductors in combination with medium-frequency transformers, is considered a promising solution for certain applications requiring flexible galvanic isolation. Among are those where space occupied by bulky low-frequency transformers is of concern and/or where advanced power quality control features are needed. In this paper, the PET for a single-phase traction on-board application is discussed with emphasis on the efficiency improvements and reductions of energy consumption during the operation on the vehicle. Several control algorithms devised to improve efficiency under light-load conditions are tested on a low-voltage prototype of the PET, and experimental results are presented demonstrating the effectiveness of the proposed algorithms.

Modular multi-pulse transformer rectifier for use in asymmetric multi-level power converter

Abstract: In one embodiment, the present invention includes a system having multiple modular transformers each including a phase-shifted primary winding coupled to an input power source and phase-shifted secondary windings each coupled to a power cell The system further includes different phase output lines coupled to a load These lines may include first, second and third phase output lines

Double ended isolated d.c.-d.c. converter

Abstract: A D.C.-D.C. down converter utilizes a controlled converter primary switching circuit and a full-wave rectified secondary circuit employing synchronous rectification. An isolation transformer having split first and second secondary windings supplies current to the full-wave secondary circuit. The gating signals for synchronous rectification are produced by a switch conduction control including a secondary switch control receiving control signals from the primary switch control through a control current isolating transformer. The secondary switch control is powered by the secondary converter circuit. Through the use of a split secondary winding of the isolation transformer and a full-wave rectifying circuit, the secondary converter circuit of the D.C.-D.C. converter may readily generate drive voltages for supply to the secondary switch control, allowing the secondary converter circuit and load to be fully isolated from the primary converter circuit and input source.