Isolation transformer

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

A Fully Integrated Watt-Level Power Transfer System With On-Chip Galvanic Isolation in Silicon Technology

Abstract: This paper presents the design and experimental characterization of a power transfer system performing a dc–dc conversion with on-chip galvanic isolation. The converter is operated in the VHF band, which enables fully integration of all the required components in silicon technology. It consists of only two silicon dice, i.e., a power oscillator with an on-chip isolation transformer and a full-bridge rectifier, which are fabricated in 0.35–µm BCD and 0.13–µm CMOS technology, respectively. A thick SiO2 layer was used, which guarantees galvanic isolation between the transformer windings. A co-design procedure for the system building blocks is proposed, which aims at optimizing the dc–dc converter performance in terms of power efficiency at a given power density. Thanks to the adopted approach, a maximum output power up to 980 mW is demonstrated with a power efficiency of 29.6%. This paper outperforms previously reported integrated inductive step-up converters in terms of power per silicon area (up to 105 mW/mm2), while providing on-chip galvanic isolation without any discrete devices or post-processing steps.

Practical switch based state-space modeling of DC-DC converters with all parasitics

Abstract: All parasitics such as switch conduction voltages, conduction resistances, switching times and ESR's of capacitors are counted in the new state-space modeling based on non-ideal switching functions. An equivalent simplified model is derived from the complex circuit with parasitics. Hence the results are very simple. The pole frequency, dc voltage gain and efficiency of the general converter, the buck-boost converter are analyzed and verified by experiments with good agreements with the theories. The procedure for determining the gain margin of controller, the turn-ratio of isolation transformer, the optimum duty factor and the switching frequency is given for an example fly-back converter

High voltage high frequency power transformer for pulsed power application

Abstract: This paper presents a new topology for a high voltage 50kV, high frequency (HF) 20kHz, multi-cored transformer. The transformer is suitable for use in pulsed power application systems. The main requirements are: high voltage capability, small size and weight. The HV, HF transformer is the main critical block of a high frequency power converter system. The transformer must have high electrical efficiency and in the proposed approach has to be optimized by the number of the cores. The transformer concept has been investigated analytically and through software simulations and experiments. This paper introduces the transformer topology and discusses the design procedure. Experimental measurements to predict core losses are also presented. The losses of epoxy coated nanocrystalline are compared to the losses in new bare (uncoated) core.

Switch current sensing with snubber current suppression in a push-pull converter.

Abstract: A push-pull converter has transistor power switches which conduct alternately to connect a DC source with the primary windings of an output transformer. A turn-off snubber circuit is connected with each power switch. When a power switch is turned on, snubber current pulses flow in the circuits connected with both switches. A switch current sensor circuit has a current transformer with an output winding inductively coupled with each of the conductors connected between the power switches and the primary windings of the output transformer. The snubber current pulses through the conductors are 180° out of phase and are suppressed in the current transformer output. The switch current signal from the secondary of the current transformer is free of snubber current pulses and is used in a flux balance circuit and in a pulse-by-pulse current limiter.

Power inverter with improved heat sink configuration

Abstract: An inverter for producing AC power from a DC source is disclosed. The inverter uses a transformer and switches to convert current from a battery or other DC source into AC power that can be used to power household appliances or other devices. The primary windings of the transformer are directly connected to a heat sink to which the switches are mounted with electrical connection between the transformer and switches being via the heat sink. The connection point on the heat sink for the primary windings of the transformer is spatially removed from the locations of the switches to facilitate heat dissipation at both locations. The primary windings of the transformer are formed from a tape or ribbon-like conductor having a cross-sectional area that allows the construction of a relatively compact transformer while also providing primary conductors of relatively large cross section. Use of tape-like conductors in the primary windings significantly simplifies the interconnection of the end of the primary winding both to a bus bar and the heat sink. Since the tape-like conductor of the transformer can be bolted directly to the flat surface of a bus bar or heat sink without using an intermediate terminal or lug, and since a relatively large contact area is established, ohmic contact resistance is minimized thus reducing the generation of heat. In one embodiment, a wedge configuration is used to mount the switches of the primary windings to the heat sink. The mounting wedge includes two flexible plate-like sections that hold both the tab and the body of the switch against the adjoining side wall of the heat sink.