Standard three-phase voltage source inverter topology [4].

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... Inverter's Output [4]. inverter (Figure 1) that uses SPWM technique, the reference waveform used for the generation of power electronics' firing pulses is formulated based on the fundamental component of the measured network voltage. Thus, any asymmetries or distortions on the network voltage waveform are not transferred on the reference waveform required by the SPWM technique. ...

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... means that the positive and negative half periods differ at the peak values and duration. This will cause the generation of a DC component on the inverter's output voltage V AO (t) between phase A and the hypothetical point O (Figure 1). ...

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... h is the harmonic order; u A h (t), u B h (t), and u C h (t) are harmonic functions for phases A, B, and C; A h is the harmonic amplitude as a percentage of the fundamental component; φ h is the angle between the harmonic and the fundamental component. DC component on voltages V AO (t), V BO (t), and V CO (t) will be equal, thus in line voltages V AB (t), V BC (t), and V CA (t) (Figure 1), the DC component will be zero. On the other hand, asymmetrical even harmonics introduce a different asymmetry on the three phases and, consequently, a DC component will appear in line voltages. ...

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... zero-crossing points of the triangular waveform with the reference waveforms define voltages V AO (t), V BO (t), and V CO (t) (Figure 1) according to the following relations: ...

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... U d is the voltage on the dc side of the inverter (Figure 1) t 0 , t 1 , . . . , t 2·Fnc are the time points corresponding to zero-crossing points of the triangular waveform with the reference waveforms. ...

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... may take positive or negative values as we saw in the previous section. As the sign is not of significance, the calculation of DC component will be based on the maximum absolute value among the three DC values for every line voltage or the voltage between each phase and the hypothetical point O (Figure 1), that is, ...

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... results for the maximum DC component are given as a percentage of the rms value of the inverter's line voltage fundamental component V o,1(rms) . The DC component was calculated using MathCad [9] not only for line voltages but also for the voltages between every phase and point O (Figure 1). Among the three calculated values, the maximum was taken. ...

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... as for low order harmonics, the DC component takes almost equal values for large values of F nc . Figure 10 depicts the maximum DC component when a 8th or 10th harmonic is present on the reference waveforms for F nc = 9. In this case, the DC component takes much higher values than for the other harmonics and the other values of F nc and is the same for these two harmonics (8th and 10th). ...

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... close examination of the results given in Figures 8-10, an approximate relation can be written for the maximum DC component versus the harmonic percentage on the reference waveforms of SPWM technique, which is presented in Table 3. ...

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... particular, in most cases the DC component is zero for M f < 0.9. A typical variation pattern for the DC component versus M f is shown in Figure 11. ...

Context 11

... respective variation for the 8th and 10th harmonic and for F nc = 9 is shown in Figure 12. Unlike the pattern shown in Figure 11, in this case the value of DC component ascends until a maximum value at about M f = 0.98 and descends until M f = 1. ...

Context 12

... respective variation for the 8th and 10th harmonic and for F nc = 9 is shown in Figure 12. Unlike the pattern shown in Figure 11, in this case the value of DC component ascends until a maximum value at about M f = 0.98 and descends until M f = 1. ...

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... Figure 13 depicts the typical pattern followed by the DC component in relation with the harmonic angle φ h in the majority of cases. For φ h = 90 • , the DC component becomes maximum while the values 0 • and 180 • give the same percentage of DC component in absolute terms. ...