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Abstract

Method for current measurement in half-bridge topologies

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Background

A number of different instrument transformers are used to determine voltage and current in regulated power electronics. Current measurement becomes more and more difficult with increasing current intensity, especially since the switching frequencies increase due to the use of modern (e.g. GaN) transistors and parasitic properties of the sensors must be minimized.

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Images & Videos

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Solution

The current measurement solution shown here in a typical half-bridge circuit is based on the concept of an easily implemented digital current observer and the use of an auxiliary winding K1 on the already existing power choke L and only a single current transformer K2. A low-cost DSP contains the typical digital control of the half-bridge circuit as well as the easily implemented current observer, which is largely processed in a standard peripheral unit of the DSP and therefore requires very few additional resources.

The effectiveness of the digital current observer in low power bridge circuits was verified in experiments. Simulations, evaluations and analyses of the latest current observer show that the measurement with such a digital current observer can also be used for high power applications.

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Advantages

• inexpensive
• isolating measurement
• small space requirement
• low parasitic effects
• low losses
• simple circuitry

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Scope of application

This insulating current measurement concept for bridge topologies therefore enables a cost-effective and compact measurement method which at the same time has only a minimal disruptive influence on the switching characteristics of power electronic breakers.

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Service

A German patent application has been granted, a European and a Chinese patent application are pending. On behalf of Paderborn University, we offer interested companies the opportunity to license and develop the technology. The functionality of the technology could also be demonstrated metrologically on the basis of the implemented prototype and through an ERDF validation project.