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Add third harmonic or triplen harmonic zero-sequence signal to three-phase signal

The Overmodulation block increases the linear region of a three-phase
PWM generator by adding a third harmonic or triplen harmonic zero-sequence
signal *V** _{0}* to
the three-phase original reference signal U

A modulation index of up to 1.1547 (exact value = 2/sqrt(3)) can be used without pulse dropping.

The Overmodulation block implements three overmodulation techniques:

The Third Harmonic overmodulation technique. In this technique the third-harmonic signal V0 subtracted from the original signal is calculated as

The Flat Top overmodulation technique. In this technique the portion of the three-phase input signal exceeding values +/−1 is computed. The three resulting signals are then summed and removed from the original signal U

_{ref}. The resulting modified signal U_{ref}* is therefore a flat-top three-phase signal that contains zero-sequence triplen-harmonics. The block outputs a value between −1 and 1.The Min-Max overmodulation technique. In this technique the minimum and maximum values of the three components of input signal U

_{ref}are summed and divided by two, and then subtracted from the input signal. The resulting modified signal U_{ref}* also contains zero-sequence triplen-harmonics. The block outputs a value between −1 and 1.

The `power_OverModulation``power_OverModulation` example
compares the three overmodulation techniques implemented in the Overmodulation
block. Choose the overmodulation technique (type 1, 2, or 3 on the
first input of the Multiport Switch) and run the simulation. Observe
the resulting waveforms in Scope 1.

The model sample time is parameterized with variable Ts (default
value of 5e-6). To run a continuous simulation, specify Ts = 0 in
the MATLAB Command Window and change the **Simulation type** parameter
of the Powergui block to `Continuous` before
starting the simulation.

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