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Sawtooth PWM

Purpose

Generate PWM signal using sawtooth carrier

Library

Control / Modulators

Description

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2-level PWM generator with a sawtooth carrier. The input m is the modulation index, and the output s is the switching function. If the modulation index is a vector the switching function is also a vector of the same width.

The block can be used to control the IGBT Converter or the ideal Converter. In these cases the modulation index must have a width of 3 to match the number of inverter legs.

The following figures illustrate different sampling methods offered by the modulator block. In the figure on the left, Natural Sampling is used. The right figure shows Regular Sampling, i.e. the modulation index is updated at the vertical flanks of the carrier. In both figures carrier signals with falling ramps are employed.

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Parameters

Sampling
Choose between Natural and Regular Sampling.
Ramp
Choose between rising and falling ramps in the carrier signal.
Carrier frequency
The frequency f   of the carrier signal, in Hz.
Carrier offset
The time offset of the carrier signal, in p.u. of the carrier period.
Input limits
The range of the modulation index. The default is [-1 1].
Output values
Values of the switching function in off-state and on-state. The default is [-1 1].