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Christoph Haederli - Les thèses en ligne de l'INP - Institut National ...

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3-L DC Link ML Converter Properties 83<br />

fundam<strong>en</strong>tal in the rectified switching function. This fundam<strong>en</strong>tal is phase shifted by π/2<br />

compared to the one g<strong>en</strong>erated by DC CM injection.<br />

4.8.3 Relationship betwe<strong>en</strong> harmonic or<strong>de</strong>rs of input curr<strong>en</strong>t and<br />

switching function<br />

The preceding two paragraphs have pointed out the quantitative relationship betwe<strong>en</strong><br />

switching function harmonics and rectified switching function harmonics. This information can<br />

now be related to the input curr<strong>en</strong>t harmonics.<br />

As the input curr<strong>en</strong>t needs to be multiplied with the rectified switching function as shown in<br />

(45), there is a convolution in the frequ<strong>en</strong>cy domain.<br />

S<br />

I _ NP _ x( I _ out _ x rect _ x<br />

ω)<br />

= S ( ω)<br />

• S ( ω)<br />

(75)<br />

Accordingly, a qualitative relationship matrix can be established.<br />

TABLE 27, RELATIONSHIP BETWEEN HARMONIC ORDERS OF LINE SIDE CURRENT, THE<br />

RECTIFIED SWITCHING AND THE NP CURRENT PER PHASE<br />

Harmonic or<strong>de</strong>r of I NP_x<br />

Harmonic or<strong>de</strong>r of I out_x DC 1 2 3 4 5 6 7 8 9<br />

DC DC 1 2 3 4 5 6 7 8 9<br />

1 1 DC 1 2 3 4 5 6 7 8<br />

2 2 1 DC 1 2 3 4 5 6 7<br />

3 3 2 1 DC 1 2 3 4 5 6<br />

4 4 3 2 1 DC 1 2 3 4 5<br />

5 5 4 3 2 1 DC 1 2 3 4<br />

6 6 5 4 3 2 1 DC 1 2 3<br />

7 7 6 5 4 3 2 1 DC 1 2<br />

8 8 7 6 5 4 3 2 1 DC 1<br />

9 9 8 7 6 5 4 3 2 1 DC<br />

abs(s x(t))<br />

The rectified switching function abs(s x(t)) has normally predominantly ev<strong>en</strong> terms, based on<br />

the fundam<strong>en</strong>tal and the 3 rd harmonic in the switching function s x(t), as shown in TABLE 26 in the<br />

previous paragraph. In steady state operation without DC offset or additional harmonics and pure<br />

sinusoidal input curr<strong>en</strong>t, this will g<strong>en</strong>erate all odd harmonics in the NP curr<strong>en</strong>t, including a<br />

fundam<strong>en</strong>tal term.

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