Comparing piezoelectric and coreless electromagnetic transformer approaches in IGBT driver

Gate drive circuits for power MOSFET's and IGBT's often require electrical insulation. Different methods of electrical insulation can be used: bootstrap circuits, transformers and optic couplers. It has been proved that Piezoelectric transformer (PT) exhibit suitable characteristics, good integration capability and can be used for both power and signal transfer in low power applications. However, coreless planar electromagnetic transformer (CT) technology is an alternative solution that can also give satisfactory results. This paper compares the performances and the capabilities of integration of these two kinds of transformers (i.e. PT vs. CT). The study and comparisons are carried out in a two-gate driver, functioning in a half-bridge inverter. The two devices have the same structure, similar electric characteristics (operating at resonance frequency in both cases), identical electric values and the dimensions of the two transformers are quite the same. Additionally, some EMI aspects regarding the use of these transformers will be considered

Non linear method for the amplification of electrical power delivered by a piezoelectric generator

The electrical supply of portable electronic devices is a crucial problem, which may be solved by harvesting a part of the mechanical energy dissipated in our environment. For the last ten years, many prototype piezoelectric generators have been proposed in research literature, offering different technological choices, but always working according to the same schematics: three different conversion stages. The first one, named mechanical application device (MAD), transforms the initial mechanical stress into a higher level or higher frequency stress. This stress is applied to the second stage, the piezoelectric device (PD). The last stage, an electronic circuit named harvesting system (HS), is essential to maximise the electrical energy delivered to the targeted electronic device. In this paper, we present an experimental test bench that can replace any association of MAD and PD. Then we describe our HS, and demonstrate its performances for our application, where the applied mechanical stress is exponential and varies with a low frequency. Thanks to this HS, the conversion from mechanical energy to electrical energy is improved, and this phenomenon can be explained by simulation, using an equivalent circuit. At last, some experimental results are commented, leading to the perspectives of this research project

A Theoretical Approach to InterCell Transformers, Application to Interleaved Converters

International audienceThe theoretical advantage of Intel-Cell Transformers over separate inductors is demonstrated in an interleaved power converter. Different practical ways to build InterCell Transformers are described. A theoretical approach dedicated to interleaved converters and InterCell Transformers analysis is presented. This analysis tool is used to understand and overcome the main drawback of InterCell Transformers. It is shown how ' the phase shifts between two adjacent phases must be modified to reduce the maximum flux density that influences core sizing and core losse

Optimal multi-phase coupled buck converter architecture dedicated to strong power system integration

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5-phase interleaved buck converter with gallium nitride transistors

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