Introduction

The purpose of this document is to provide instructions for connecting components that support interpolation (a.k.a. TSB components in this documentation) within a circuit to achieve more accurate and stable results. The components covered include:

• Half-bridge converter;

• 3-level NPC arm;

• 3-level T-type arm;

• Single-phase cycloconverter.

The first section presents theoretical background on the design and modeling of power converters. Building on this foundation, the document provides guidelines for connecting TSB components to optimize their performance.

Sources and their natures

A static converter is a meshed network of electrical components that serves as a linking, adapting, or transforming stage between two sources, typically a generator and a load.

Open

Power static converter definition

Sources are categorized into two types: voltage sources and current sources. Each source can function as either a generator or a receptor (load).

• Voltage Source: A source is classified as a voltage source if the voltage across its terminals cannot experience discontinuity due to variations in the external circuit. The capacitor is the most representative example, as an instantaneous change in voltage across its terminals would require an infinite current to accommodate the corresponding instantaneous change in charge;

• Current Source: A source is classified as a current source if the current flowing through it cannot experience discontinuity due to variations in the external circuit. The inductance serves as the primary example, as an instantaneous change in current would require an infinite voltage to achieve the corresponding instantaneous change in flux.

Alternatively, the nature of a source can be defined using the concept of instantaneous impedance, which is the limit of the source's impedance as the Laplace operator approaches infinity. This instantaneous impedance may be zero, finite, or infinite.

• A source is a voltage source when its instantaneous impedance is zero;

• A source is a current source when its instantaneous impedance is infinite.

Source nature modification

Connecting an inductance of appropriate value in series with a voltage source (a dipole with zero instantaneous impedance) transforms the voltage source into a current source. Similarly, connecting a capacitor of appropriate value in parallel with a current source (a dipole with infinite instantaneous impedance) transforms the current source into a voltage source.

Open

Source nature modification

Interconnection of sources

The laws governing source interconnections can be summarized as follows:

• A voltage source should never be short-circuited but may be open-circuited.

• A current source should never be open-circuited but may be short-circuited.

From these principles, it follows that:

• Two voltage sources should never be connected in parallel.

• Two current sources should never be connected in series.

Open

Basic interdictions of source interconnection

Connection of TSB components

As defined in the previous sections, eHS Gen 5 TSB components exhibit different source behaviors at their terminals, as illustrated in the figure below:

Open

TSB components and their source nature.

Certain configurations may lead to poor or unstable results, as shown in the example provided in the figure below:

Open

Example of bad components connection with a half-bridge

It is important to note that the cycloconverter exhibits asymmetrical behavior. Ideally, a cycloconverter should behave symmetrically, meaning its ports could be interchanged by adjusting the gating configuration. However, the current model employed in eHS renders the component asymmetric, causing it to behave differently depending on the connections at each port.

Open

Cycloconverter asymmetry

Reference

[1] F. Boudry, “Power converters: definitions, classification and converter topologies“, CERN - Specialized course on power convertors, Geneva, 2006.